CS241103B2 - Folded tubular housing and method of manufacturing - Google Patents

Abstract

The folded tubular casing according to the invention consists in that it consists of a tubular core resisting deformation and reduction of the core opening by an expansion force directed into the casing and a moistened cellulose food casing with a moisture content of at least 13% of the total weight of the casing, preferably with a moisture content of from 16 to 35% of the total weight of the casing, folded and compressed on said tubular core with a compression ratio of at least 70 and a compression efficiency of at least 0.50. Several methods of manufacturing this folded tubular casing are also described. The folded tubular casings according to the invention are intended for use in the food industry, in particular in the production of sausage products of all kinds.

Description

(54) Folded tubular casing and method of manufacturing same

The folded tubular casing according to the invention consists in that it consists of a tubular core resisting deformation and reduction of the core opening by an expansion force directed into the casing and a moistened cellulose food casing with a moisture content of at least 13% of the total weight of the casing, preferably with a moisture content of from 16 to 35% of the total weight of the casing, folded and compressed on said tubular core with a compression ratio of at least 70 and a compression efficiency of at least 0.50.

Several methods of manufacturing this folded tubular casing are also described.

The folded tubular casings according to the invention are intended for use in the food industry, especially in the production of sausage products of all kinds.

241103 ^of

The invention relates to cellulose food casings, in particular to folded tubular cellulose food casings fitted in a compressed state on rigid hollow tubular cores in a highly compressed state to form sections of folded casings having significant additional length for filling, increased structural stability and strength and in addition having use in hitherto conventional dimensions on filling nozzles of larger diameters than has heretofore been possible.

The invention is particularly useful in the production of sections of folded casings used in the food industry in the production of sausage-like products of all kinds and also has considerable advantages in use as packaging pieces for food products such as boneless meat pieces.

Artificial food casings used worldwide in the production of a large number of different meat and other food products, such as various types of sausages, cheese rolls, turkey rolls, etc., are usually made from regenerated cellulose and other cellulosic materials.

These casings come in a variety of types and sizes for the production of various types of food and are either reinforced or unreinforced, with reinforced casings, generally referred to as "fibrous", having a reinforcing fabric of fibers embedded in the wall.

A common feature of many manufactured food products, especially meat products, is that a mixture of edible components, generally called an emulsion, is loaded into a casing under pressure and the processing of the food product is carried out subsequently.

The food product may also be stored and shipped in a casing, although in many cases, particularly for small sausage-like products such as hot dogs, the casing is removed after processing of the product is complete.

The term small food casings generally refers to casings used in the production of small-sized products such as sausages. As the name suggests, this type of casing has a small diameter when filled, generally having a filled diameter of 13 to 40 mm and is most often supplied as unreinforced thin-walled tubes of very large length.

For convenient handling, these casings, which can be 20 m to 50 m or more in length, are folded and compressed into products generally referred to as folded casing sections with a length of about 20 cm to 60 cm. Folding machines and their products are shown, among others, in patent documents Sp. st. a. No. 2 983 949 and 2 984 574.

Large-diameter food casings, which is a general term for casings used in the production of generally larger food products, such as salami, bolognese, meat loaves, cooked and smoked ham rolls, etc., are manufactured for filled diameters from 40 mm to 200 mm and more.

These casings generally have a wall thickness three times that of small food casings and are manufactured with a fibrous fabric reinforcement embedded in their wall, although they can also be manufactured without such reinforcement.

For many years, large diameter food casings were supplied to food manufacturers in an inflated state cut into pieces of specified length from about 0.6 m to 2.2 m. Later, but before the invention, large diameter food casings of both the reinforced and non-reinforced types were supplied in the form of folded sections containing up to 65 m of casing for loading into high speed equipment.

In the manufacture and use of artificial food casings, it is important to control the moisture content of the casings. While the folded sections of cellulose casings of the type used in the invention should have a moisture content of at least 13% of the total weight of the casings, the moisture level may vary.

When small food pouches are made from regenerated cellulose, it is generally preferred that they have a water content of about 14 to 18% of the total weight of the pouch so that charging can be carried out without damaging the pouches.

This relatively narrow moisture content range is also important because at lower moisture contents, excessive tearing of the cases occurred during charging, and at higher moisture contents, the cases were too plastic, resulting in overfilling.

The large diameter food casings described above have been improved in the past in that the folded and compressed sections of the casings were supplied in a pre-moistened state, so that the previously used and difficult step of moistening such casings immediately prior to loading was eliminated.

The moisture content of large diameter fiber-reinforced food casings supplied in a folded and pre-moistened state was typically in the range of about 16 to 35% of the total weight of the casings.

A specific humidity level can be selected to suit the user's requirements and preferences. If the humidity content is high and the cases are stored for a long time before charging, it is advisable to take measures against mold and bacteria.

One solution according to the invention consists in limiting the activity of the water added before or during charging with a sufficient amount of substances such as propylene glycol or glycerin. These substances also act as plasticizers and humectants in the capsules to be folded and compressed.

The techniques for folding cases described above in the aforementioned patents and elsewhere generally consist of continuously feeding a length of flat case from a supply, for example from a reel, into a folding machine where it is inflated with a low pressure gas, usually air.

The inflated sleeve is guided through a series of folding rollers which fold the sleeve against the restrictor and slide it onto the folding mandrel until a predetermined length of the folded sleeve is reached.

In a folding machine with a floating folding mandrel, which is described, for example, in the patent document Sp. st. a. 3 766 603, the folded sleeve is then moved linearly over or from the limiting member onto the extended part of the folding mandrel, on which it is compressed to a section of the desired length.

In a folding machine with a pulled folding mandrel, which is described, for example, in patent document Sp. st. a. No. 2,583,654, the folding mandrel with the folded sleeve placed thereon is rotated to another position, in which the folded sleeve is compressed to a section of the desired length.

Normal compression achieves a section length equal to about 1.0% to 1.2% or 1.3% of the original unfolded length of the casing.

Patent document Sp. st. a. c. 2 001 461, inventor Hewitt, describes how the original length of the casing equal to 1 006 cm is reduced by folding and compression to a section of length 10 cm. Hewitt further states that the probable limiting ratio of the section of the folded and compressed casing to the original length of the casing is equal to 1/130. However, Hewitt does not consider the problems associated with the production of such a highly compressed section of the folded casing in commercially advantageous lengths and does not consider the importance of the diameter of the casing.

Prior to the invention, the ratio of the original length of the casing to the length of the folded and compressed casing section was typically 70 to 100 in industrial practice. This ratio is referred to as the compression ratio and is a reversal of the ratio reported by Hewitt.

Another way to quantify the amount to which the original length of the casing is compressed in the folded and compressed section is the compression efficiency. The compression efficiency is defined as the ratio of the volume of the folded and compressed casing of unit length divided by the volume of the same unit length that the solid material would have inside, and can be expressed by the following equation:

L _c x /2 x FW xt /

PE - Π - /OD - ID / x L ^S where denotes

PE compression efficiency,

L _c the length of the case,

L _is the length of the section of the folded case,

FW width of the flat housing, t wall thickness of the housing,

OD outer diameter of the section of the folded casing and

ID is the inner diameter of the folded sleeve section.

This calculation implicitly includes the specific gravity and/or density of the casing material. Analysis of the relationship shows that the ratio actually refers to the volume of the flat casing stock contained in the compressed casing section divided by the volume of a hollow cylinder having the same dimensions as the folded casing section. The extent to which the compression efficiency is increased is measured by comparing its numerical value to one.

Since the compression ratio is a ratio to L _g , the compression efficiency can also be expressed as follows:

x FW X t

PE = /compression ratio/ 11 2 2 — /OD - ID /

It is clear that for a given compression efficiency, the compression ratio varies with the difference between the outer diameter and the inner diameter of a section of a compressed sleeve of a given size. Furthermore, since the outer diameter is necessarily limited by the width FW of the flat sleeve used to form the section, increasing the diameter differences in order to increase the compression ratio must result in a reduction in the size of the bore or inner diameter.

While the requirements of maximum section opening and maximum compression ratio work against each other, the fact remains that compression efficiency is maximum at a given compression ratio when the section internal diameter is maximum.

It is usually desirable to use the maximum inside diameter charging nozzle for a given case size to achieve maximum throughput and minimum charging pressure. Another reason for using the maximum diameter charging nozzle is to reduce the risk of degreasing.

Defatting is a phenomenon that occurs when the flow of a meat emulsion through a charging nozzle at high speed causes the emulsion to degrade and the water and fat to separate. The water and fat then accumulate between the surface of the finished sausage product and the cellulose casing during processing, resulting in an unsatisfactory sausage product that has an unacceptable appearance. The charging speed decreases as the inner diameter of the charging nozzle increases.

The goals that the technology of case folding sought to achieve were to produce a section of folded and compressed case that could be stretched to length and loaded on a loading device smoothly, without mechanical defects or tears, to ensure smooth production, to have sufficient structural and mechanical strength, cohesion, to be resistant to the usual rough handling during packaging, storage, handling and loading on a loading device, to produce the maximum technically possible number of products from a given length of compressed case section using a loading nozzle of the maximum possible diameter.

Typical values of compression ratio and compression efficiency for the prior art can be calculated from the data in the patent document Sp. st. a. No. 3,528,825, inventor Doughty. In the part from line.75 in column 5 to line 5 in column 6 there is a description of a folded section of the casing containing a length of casing of 30 m with an inflated diameter of 1.75 cm with a wall thickness of 0.0254 mm.

The compressed sleeve section has an outer diameter of 2.22 cm and an inner diameter of 1.7 cm and a length of 41.28 cm. Using these data and the above formula for compression efficiency, we can find that the prior art described by Doughty achieves a compression efficiency of 0.374. The compression ratio of the sleeves according to this prior art was 70, 30 m were folded and compressed into a section of 41.28 cm in length.

The congruence of the folded and compressed section is determined by measuring the bending moment in newton metres at the fracture of the section. The folded compressed sleeve section is placed on two V-profile supports fixed to the base plate at a distance /D/ equal to about 80% to 90% of the length of the tested section. Such a member with two V-profile projections spaced /D-101.6/ mm apart is placed symmetrically on the upper surface of the section.

A manual mechanism equipped with a force indicator exerts downward pressure on the section and the force increases until the section breaks. By suitably calibrating the force indicator, it is possible to achieve that the reading of this indicator directly indicates the bending moment in Nm or Ncm. In general, in practice, the required cohesion of the section is about 13.5 Ncm, a particularly suitable and preferably desired cohesion is about 18.2 Ncm.

Because the most important measure of the functionality of a case is the ratio of the diameter of the opening of the folded and compressed case section to the diameter of the charging nozzle, a "drop" test was developed.

To simulate the placement of the folded section on the charging nozzle and thus measure the effective internal diameter of the folded section, a test was designed in which the folded section is placed on the upper end of a stainless steel rod placed vertically and longer than the folded section and allowed to fall under its own weight to the lower end of the rod.

In a special case, the rod may be placed vertically on a table. The folded section is placed over the upper end of the rod and then released. If it falls onto the table surface, the drop test is successful. A set of rods with diameters graduated in 0.0254 mm increments, for some ranges of bushing diameters in 0.0508 mm increments, are used.

The composite section is tested sequentially, starting with the smallest diameter rod, until it reaches a rod at which it no longer falls freely over the entire length of the rod. The largest diameter of the rod at which the sleeve section falls freely over the entire length of the rod is its effective internal diameter.

In the manufacture of folded cellulose sections of cases, individual sections have slightly different internal diameters due to irregularities in the folds in the section opening. For this reason, it is necessary that the drop test be carried out on a larger number of folded sections, at least 10, and that an arithmetic average be created to determine the functionality of the entire group in terms of loading nozzle fit.

As mentioned above, the mean values of the drop test tolerance are in the range of thousandths of a mm. For example, if the minimum requirement is 12.675 mm, a mean drop test value of 12.670 would no longer be acceptable, because a significant number of sections in the group represented by a mean value of 12.0^0 nm would not be able to function on a 12.675 mm diameter charging nozzle.

One of the most important factors in the assembly of small diameter food casings is the quality of cohesion, i.e. the durability of the assembled section as a single product. The cohesion of the sections is particularly important to ensure the suitability of such sections for use in automatic loading equipment, for example, equipment for the production of sausages and similar products.

A separation or tear in the folded section before it is placed on the loading nozzle renders it unusable in such an automatic loading device. For this reason, any processing of the tubular food casing to be formed into a folded section must not adversely affect the cohesion of the section, but rather should enhance it.

In recent years, considerable efforts have been made in the food casing industry, especially in small diameters, to develop systems for producing highly cohesive casing sections. Chemical treatments have been introduced, described, among others, in patent file Sp. st. a. No. 4,137,947.

Conventional folding on modern folding machines produces folded sections of casings with a discernible angular displacement between a plane perpendicular to the longitudinal axis of the section and the plane in which the folded crease lies. This is called the bend angle.

A conventional folded coreless section according to the invention having a bend angle of this nature has a cohesion and structural strength which is substantially higher than a section of the same type which has been folded with a fold perpendicular to the longitudinal axis of the sections, since the total length of the section is somewhat like a stack of interconnected, nested cones.

It has now been discovered by the inventors, particularly for small diameter casings used for sausage type production, that when a conventional coreless folded section is highly compressed in an attempt to achieve a maximum compression ratio, the cohesion or structural strength of the compressed section is compromised such that it becomes non-functional.

This means that the section becomes brittle, breaks easily and cannot be fitted to the charging nozzle. It is thought that this phenomenon arises when high longitudinal compressive forces tend to bulge the geometry of the nested cones created during the folding process.

The inventors have also discovered that when a cylindrical casing is folded, i.e. when it is converted from a flat tube shape to a folded and compressed section, as explained above, large inward radial forces are developed in the resulting folded section while achieving high compression efficiencies.

The magnitude of these large forces was not noted until the composite sleeve sections were highly compressed on the tubular cores of the invention and it was found that the substantially rigid cores somewhat reduced in diameter over time.

It was previously known that the inner diameter of conventional coreless sleeve sections exhibits significant shrinkage upon removal from the collating mandrel immediately after compression, and further gradual shrinkage occurs over a period of one week or more, but the magnitude of the forces causing such diameter shrinkage was not noted prior to the present invention.

The inventors have further discovered that the magnitude of these radially inwardly directed forces is proportional to the longitudinal compressive force used to compress the section to its initial compressed length prior to removal of the folding mandrel. That is, the radially inwardly directed forces increase as the longitudinal compressive force increases.

British Patent No. 1,167,377 describes a section of pleated tubular casing supported on a hollow core which is shaped and dimensioned to fit around a charging nozzle. Frictional tension within the section is described to prevent the core from sagging or slipping out.

r t

It is stated that the core may be made of any material from synthetic plastic material to thin cardboard. According to one method previously developed, it is made of polyvinyl chloride extruded into a cylinder shape with a wall thickness of about 0.254 mm.

The product according to the said patent specification was supplied as a plastic tubular casing of polyvinyl chloride stacked on a core of cellulose acetates with an internal diameter of 24.993 mm and a wall thickness of 0.292 mm. The invention according to the said British patent has never been applied to a folded cellulose tubular casing.

In addition to the use described above, the use of a hollow core as a support for a large diameter folded casing has been known for many years. However, all known prior applications of the core for folded cellulose casings have been to provide integrity and to limit swelling upon wetting.

The rods were used with small cases for shipping and handling while developing cohesive sections of cases. The folded case was removed from the rod and slid onto the charging nozzle when in use.

In recent years, the manufacture of cellulose food casings has moved away from the use of internal tubes for confinement and reinforcement and has moved to external confinement and reinforcement means such as nets and shrink or flexible film for medium and large diameter casings. Small casings were used as cohesive sections without any reinforcements.

The main object of the present invention is to provide a highly cohesive folded sleeve section product, where the sleeve is folded and compressed to a higher compression ratio than previously achieved in the prior art, while maintaining an acceptable opening size in conjunction with high compression efficiency.

Another object of the present invention is to provide a product with a folded casing section of high cohesion and high compression efficiency in a structure and type usable in a wide range of casing sizes and types used in the food industry.

Another important object of the present invention is to provide a product with a folded casing section having a high compression ratio coupled with a high compression efficiency, both of which are higher than those currently achieved in the food casing industry, while eliminating all possible problems known from the prior art associated with a lack of structural strength or cohesion.

Another important object of the invention is to provide a high density folded sleeve section with a core as a product that has suitable physical properties for absorbing the high radial inward forces exerted during folding of a cylindrical sleeve and its subsequent compression to a high compression ratio.

Another important object of the invention is to develop a method for producing a folded section of a high density cored casing on existing folding machines with only minor modifications to produce the product of the present invention.

Another object of the invention is to provide a product with a casing having a combination of a larger opening and a higher compression ratio than can be achieved with a product without a core.

Another important object of the invention is to provide a high density, folded case with a core that would allow specific standard case sizes to be fitted to larger charging nozzles than has been possible heretofore.

The contribution that the folded case of the present invention makes to technology lies in the much more efficient loading of food products of all kinds into suitable cases.

A particular object of the invention is to obtain a section of a high-density pleated casing with a core, where the core replaces the charging nozzle of a charging machine and thus becomes part thereof.

An additional specific object of the invention is to provide a high density folded sleeve section, the core of which can optionally be used as a support tube for threading onto a charging nozzle of a charging device or alternatively as the charging nozzle itself and having a connecting means of one type or another fitted to the core and located within the unfolded portion of the folded sleeve.

The subject of the invention is a folded tubular casing, characterized in that it consists of a tubular core resisting deformation and reduction of the core opening by an expansion force directed into the casing and a moistened cellulose food casing with a moisture content of at least 13% of the total weight of the casing, preferably with a moisture content of from 16 to 35% of the total weight of the casing, folded and compressed on said tubular core with a compression ratio of at least 70 and a compression efficiency of at least 0.50.

According to a preferred embodiment, the cellulose food casing is provided with a fibrous reinforcement.

Another advantageous feature is that the casing comprises a tubular core with an internal diameter equal to or greater than that of the casing folded and compressed under the same folding and compression conditions, but without the core _.

The housing preferably according to the invention comprises a tubular core with a wall thickness of at least 0.5 mm.

An advantageous feature of the invention is that it comprises a food casing with an internal diameter equal to at least 50% of the inflated diameter of the casing.

In contrast to the prior use of cores, the present inventors have discovered a novel use of cores, such that they are designed to limit the radial inward force in a folded sleeve to such an extent that not only can compression ratios be achieved substantially higher than in the prior art, with coreless sections compressed and folded under the same conditions, but these higher compression ratios can be achieved with sleeves having the same or even larger hole sizes than can be achieved with the aforementioned comparable coreless folded sleeve sections.

This is contrary to the expectation of the skilled person, that is, that the core occupies a certain space and thus reduces the effective opening of the housing section. Therefore, one would expect that the core would have a negative effect on the compression ratio.

Contrary to this expectation, the cellulose casing of the invention can provide a substantially higher compression ratio without reducing the casing opening, thereby creating a pleated casing with a core that has a compression efficiency higher than a casing section free of a core. An additional feature of the invention is that it creates a pleated tubular casing of increased structural integrity and strength.

The invention can be used advantageously in particular on a loading device for packaging piece meat, such as whole boneless hams and the like, where a casing core is used instead of a loading nozzle. Such a loading machine for whole boneless hams is, however, a separate invention in itself and within the scope of the present invention it is only a question of adapting a high density casing with a core for use on such a filling machine.

Possible implementation of the invention is the folding of a case with a core, the core of which can be an alternative. ·; ivn í used as a carrier Lrmk'> oi-nuení on the charging nozzle of the charging device or as the charging nubine itself. having a p_ . . _Λ ' -o-ac i means of one or the other, mounted on the core and placed'· inside the breakable L.part of the folded case.

The invention thus generally comprises a tubular core in combination with a controllably wettable folded cellulose casing having a moisture content of at least 13% of the total weight of the casing, folded and highly compressed on said core to a high compression ratio and compression efficiency of at least 0.50, the compression ratio and compression efficiency being higher than a casing of the same length folded and compressed under the same conditions but without a core, thereby developing a high inwardly directed expansion force.

Another feature of the combination according to the invention is that the core is sufficiently rigid to resist deformation and reduction of the housing opening under the influence of a high expansion force directed into the housing. For the purposes of this comparison between folded and compressed housings with and without cores, the housing without core has no longitudinal external restraint.

The term folded and compressed under the same conditions means that the folding method and the device for performing it, for example including a folding means and a folding mandrel, and the final compression method, device, compressed length or compression force are substantially the same.

In a preferred embodiment of the invention, the achieved compression efficiency is 0.60 or higher.

In a preferred embodiment of the inventive case, based on the drop test described above, the core has an internal opening with a diameter at least equal to the diameter of the opening of the same case folded and highly compressed under the same folding and compression conditions, but without the core.

In a preferred embodiment, the casing is of a small cellulose type with an inflated diameter of less than 40 mm and is compressed to a compression ratio of at least 100.

The subject matter is also a method of producing a folded tubular casing, the essence of which consists in producing a cellulose food casing with a moisture content of at least 13% of the total weight of the casing, the inner surface of the circumference is threaded onto one end of a mandrel having a reduced diameter at the other end, the casing is folded onto this mandrel, a coaxial hollow core is inserted onto the end of the mandrel of reduced diameter, resisting deformation and diameter reduction due to the expansion force directed into the casing resulting from its compression, the folded casing is linearly moved along the mandrel onto the outer surface of the coaxially placed core and the folded casing is compressed onto the core.

An alternative method of manufacturing a folded tubular casing according to the invention consists in producing a cellulose food casing with a moisture content of at least 13% of the total weight of the casing, the inner circumference of the casing is threaded onto one end of a mandrel, the casing on the mandrel is folded and compressed, a hollow core is formed that resists deformation and diameter reduction due to the expansion force directed inwardly of the casing resulting from its compression, and the folded and compressed casing is linearly moved from the other end of the mandrel to the outer surface of the core for compression.

Another embodiment of the method according to the invention consists in producing a cellulose food casing with a moisture content of at least 13% of the total weight of the casing, the inner circumference of the casing is inserted onto one end of a mandrel, the casing is folded on the mandrel, a hollow core is formed that resists deformation and diameter reduction due to the expansion force directed inwardly of the casing resulting from its compression, the folded casing is moved from the other end of the mandrel to the outer surface of the hollow core and then the folded casing is further compressed. According to a preferred embodiment of the method, the hollow core is supported by a second mandrel.

In this manufacturing method according to the invention, it is advantageous if the folded food cellulose casing is transferred to the second position before being transferred from the second end of the mandrel to the hollow core.

Another embodiment of the method according to the invention consists in producing a cellulose food casing with a moisture content of at least 13% of the total weight of the casing, forming a hollow core that resists deformation and diameter reduction due to an expansion force directed into the casing resulting from compression, the inner circumference of the hollow core is longitudinally slid onto the outer surface of the hollow core, the casing is folded on the hollow core and the mandrel, and then the casing is compressed on the hollow core, after which the delaminated and compressed casing is longitudinally pulled off and the core is removed from the mandrel.

Another embodiment of the method of the folded tubular casing according to the invention consists in producing a cellulose food casing with a moisture content of at least 13% of the total weight of the casing, the inner surface of the casing is applied to one end of the mandrel, the casing is folded on the mandrel and the folded casing is compressed on the mandrel, a hollow core is formed that resists deformation and diameter reduction due to the expansion force directed inwardly of the casing resulting from its compression, the folded and compressed casing is longitudinally pulled off the first end of the mandrel and slid onto the surface of the hollow core.

Another embodiment of the method according to the invention consists in producing a cellulose food casing with a moisture content of at least 13% of the total weight of the casing, applying the inner surface to the first end of the mandrel, folding the casing on the mandrel, forming a hollow core that resists deformation and diameter reduction due to the expansion force directed inwardly of the casing resulting from its compression, moving the folded casing supported on the mandrel to a second position, transferring the folded casing from the first end of the mandrel to the outer surface of the hollow core and then compressing the casing on the core. According to a preferred embodiment of this method, the hollow core carries a second mandrel. Preferably, the partially compressed casing is also transferred to the hollow core and the second mandrel.

The moisture content preferred for different types of casings may vary. More specifically, the moisture content of larger diameter, solvent-moistened pleated fiber casings may preferably be from 16 to 35% of the total casing weight.

Casings of smaller diameters, used for sausage-type products, etc., preferably have a moisture content of 14 to 18% of the total weight of the casings.

The tubular core of the folded tubular sleeve according to the invention must be sufficiently rigid to resist deformation and diameter reduction due to the inwardly directed expansion force, whereby slight deformation and diameter reduction will occur, but as long as these values are not too large, they are acceptable.

The core diameter can vary from 9.525 mm to 127.0 mm or more, depending on the casing diameter and the desired hole size. The casing wall thickness can also vary depending on the product, its adaptation and use, and further depending on the core material, but generally the wall thickness of a tubular core is in the range of 0.051 cm to 0.254 cm.

The accompanying drawing shows an example of an embodiment of the invention, where Fig. 1 is a front view of a device for producing a folded tubular casing according to the invention according to one alternative of the method according to the invention, showing the process of folding a casing produced from a continuously fed material, Fig. 2 shows the same device in a state where the folding of the casing is completed and the folded casing is transferred to the compression section of the device of Fig. 1, Fig. 3 shows the introduction of a compression force to form a section of a folded tubular casing according to the invention on a core mounted on an extended part of a folding machine, Fig. 4 is an isometric view of a product according to the invention showing a folded and compressed tubular casing mounted on a hollow core, Fig. 5 is an illustration of a variation of the invention adapted for use as a loading element on a loading machine for producing products from pieces of meat, Fig. 6 is an isometric view of an embodiment of a product according to the invention particularly useful for loading medium-sized food products, where the core can be used as a support member i attached to the charging nozzle or as the charging nozzle of the charging machine itself, Fig. 7 ie nirvynalny invention useful in the production of sausage-like products of small diameters natí only replaces the charging nozzle of the charging machine, Fig. 8 is a graph showing ;- i · skon et·!

as a function of the compression ratio for folded sections of coreless casings and - ' i ¹ cz non-fibrous casing of length 32.25 m and size 25, Fig. .9 is a graph showing..ri. : -e , and ae-a as a function of the compression ratio for sections of coreless casings and with cores of a solid casing of length 32.25 mm and size 25, Fig. 10 is a graph showing p ·. as a function of the compression ratio for sections of coreless casings of sizes ii , - and 27 made of cellulose without fibrous reinforcements, all sections having the same .iáliw, . '1 o a graph showing cohesion as a function of compression ratio for sections of casings o ipnvi a-.c Fig. 10, Fig. 12 is a graph showing the maximum achievable compression ratio for sections of casings /product according to .· 1 í :ro with and without cores for medium casing sizes in the range of 43 to 60 for mounting on a 27.254 mm diameter charging nozzle and Fig. 13 is the same graph as in Fig. 12 for medium-sized fibrous casings from 70 to 100 for mounting on a 39.522 mm diameter charging nozzle.

In Figs. 1 and 2, a typical folding machine of the floating mandrel type is shown, designated by reference numeral 11, which has a folding mandrel 13 extending through a folding head 15. The inflated casing 17 is fed onto the folding mandrel 13 by a pair of feed rollers 19 and cooperating feed belts 21. The folding head 15 consists of a series of folding discs 23, usually three, through which the inflated casing 17 passes.

The folding discs 23, in cooperation with the retaining straps 25, fold the inflated case 17 in a known manner. The folding discs 23 are of a known type, which is described in the patent document Sp. st. a. No. 3 461 484.

The progress of the folded case 17 on the folding mandrel 13 is slowed by a series of retaining belts 25 in order to form a substantially regular pattern of folds and a partially compressed folded case 17. After the initial folding and formation of the folds, the case 17 is conveyed by the retaining belts 25 further along the folding mandrel 13 to the first clamp 27.

For the purpose of transferring the folded sleeve 17 to the hollow, substantially rigid tubular core 31 and compressing it thereon, the first clamp 27 is deflected from its path and the folded length of sleeve 17 is moved manually or by conventional automatic means to the position shown in FIG. 2 up to the second clamp 29.

In this position, the folded length of the sleeve 17 is placed on a hollow tubular core 31 slid onto the tapered portion of the folding mandrel 13, as can be seen in Fig. 3, which is an enlarged portion of the right side of Fig. 2.

The final compression of the sleeve 17 on the hollow tubular core 31 is carried out by the compression tool 33, which moves linearly towards the second clamp 29 until the sleeve 17 is compressed to the desired length.

A retaining disc 35 is preferably inserted between the end of the sleeve 17 and the second clamp 29 so that when the product is removed, the sleeve 17 is securely held on the hollow tubular core 31 and prevents it from slipping.

After the product, i.e. the high density section of the casing, is completed as described above, the second clamp 29 is moved out of the holding position and the product is removed.

The product according to the invention can for example be assembled (by sliding the folded and partially compressed casing 17 on the hollow tubular core 31 in the manner described above. Fig. 3 shows the folded and partially compressed casing 17 moving rectilinearly on the hollow tubular core 31 placed coaxially with the folding mandrel 13 on its narrowed part, the compressive force being developed by the compression member 33.

Other methods may be used to place the folded sleeve 17 on the hollow tubular core 31. For example, on a floating mandrel folding machine such as that described above, the folded sleeve 17 may be fully compressed on the mandrel in the machine and then transferred to the tubular core 31.

It is also possible to remove the folded and partially compressed core 17 completely from the folding machine on the support bar and insert it into a separate compression device, in which the folded sleeve 17 is pushed onto the hollow tubular core 31 and compressed. Alternatively, the hollow tubular core 31 can be placed on a floating mandrel and then positioned thereon so that the sleeve 17 is folded onto the hollow tubular core 31, then completely compressed thereon, and the fully compressed section of the folded sleeve 17 is then removed from the mandrel.

Another folding system using a folding machine with a pulling mandrel is described in patent document Sp. st. a. No. 2583654. This folding system can be used in the manufacture of products according to the invention and allows the casing 17 to be folded directly onto the hollow tubular core 31 for further compression thereon. In one embodiment, the hollow tubular core 31 is placed on the pulling mandrel and positioned thereon so that the casing 17 is folded onto the hollow tubular core 31 and then the fully compressed section of the casing 17 is pulled off the mandrel.

In an alternative embodiment, the sleeve 17 can be folded and compressed on the extraction mandrel in the usual manner and the folded and compressed sleeve 17 can be pulled off the mandrel and pushed onto the hollow tubular core 31. In another embodiment, the sleeve 17 can be folded and partially compressed on the extraction mandrel, the mandrel is then moved to a new position coaxial with the hollow tubular core 31, the partially compressed section of the folded sleeve 17 is slid off the mandrel onto the hollow tubular core 31 and then completely compressed thereon.

It is also possible to remove the folded and partially compressed casing 17 from the folding machine with the extraction mandrel onto a support rod and then transfer the partially compressed folded casing 17 from there to a hollow tubular core 31 placed on a special compression device, where the section of the casing 17 is fully compressed on the hollow tubular core 31.

Achieving the maximum possible compression ratio in the product according to the invention requires a large compression force, which then exerts large radial, inwardly directed forces in the compressed collapsible sleeve section 17.

Since the preferred method of manufacturing the product according to the invention involves compressing the folded sleeve 17 already placed on the hollow tubular core 31, a low coefficient of friction between the sleeve 17 and the hollow tubular core 31 is desirable.

Example VII explained below shows that a higher compression ratio can be achieved if the material of the hollow tubular core 31 is, for example, high density polyethylene having a relatively low coefficient of friction compared to polypropylene or polystyrene which have a higher coefficient of friction.

Fig. 4 shows the product of the invention, namely a moistened cellulose food casing 17, folded and compressed on a rigid tubular core 31 to a compression ratio and compression efficiency higher than has been conventionally achieved heretofore.

Also shown in Fig. 4 are retaining discs 35 which may optionally be arranged at either end of the folded sleeve 17 to maintain it in a compressed state on the hollow tubular core 31.

Fig. 5 shows a preferred embodiment of a high density collapsible core case used with a detachable charging nozzle. In this embodiment, a flexible retaining member 37 is mounted on a hollow tubular core 31 and is housed within the expanded portion of the case 17, which has been pulled out of the collapsed and compressed case 17 via the flexible retaining member 37 and the end of the hollow tubular core 31, which is also the charging nozzle, and is clamped at the end to form a closure for the product to be loaded into the case 17. At the other end, the hollow tubular case 31 has a flange 39 for easier attachment to a charging device.

Fig. 6 shows a high density core product according to the invention adapted for a case carrier or support flange to be fitted onto the charging nozzle of a charging device. When used in such a manner, the flange £9 of such a product can be connected to a charging machine mechanism which provides for the reciprocating movement of the entire case to produce displacements when these are required during the charging process.

An arrangement very similar to that shown in Fig. 6 may alternatively be used as a sleeve which includes an adapter or retaining member, in which case the unfolded portion of the housing 17 is pulled over the adapter and the end of the housing is clamped to retain the product being loaded into the housing 17.

Fig. 7 shows a product according to the invention adapted for use in loading small sausage-like products and provided with a fastening member 4i designed for direct attachment to a loading machine, the hollow tubular core 31 of the product representing a conventional loading nozzle.

In this case, the casing 17 is partially folded, pulled over the calibration element 43 and the end of the hollow tubular core 31 and closed to seal the product to be loaded. It is particularly advantageous to provide large lengths of casing 17 in a given length of the folded casing section for loading small sausage-like products, since the production of such products is largely carried out on automatic loading equipment with high loading speeds.

The use of the product according to the invention allows for the use of much greater lengths of folded casing 17 in a given length of section of folded and compressed casing 17 for much more efficient operation of such loading devices and at the same time, the high requirements for dimensions and consistency of casings used on these machines are met.

Fig. 7 also shows the fold angle-Θ of the case ^: 17.in the folded and compressed section according to the invention. Conventional folding.on modern - folding machines gives sections of folded cases with a discernible angular offset between the plane perpendicular:to the longitudinal axis of the folded case section with the plane in which the compressed fold:of the case lies: *

A core-free section having a fold angle of this type has been found to have significantly higher cohesion and structural strength than a section of the same type of casing folded with a fold angle perpendicular to the longitudinal axis of the section, since the entire length of the section is a structure similar to a layer of stacked cones. The tubular core provides sufficient structural rigidity, thus reducing the effect of the fold angle on the cohesion of the section.

One of the reasons for introducing this fold angle (-) in the sleeve sections according to the invention is to delay the longitudinal elongation of the section. The folded sleeve sections tend to elongate immediately after being withdrawn from the folding mandrel or compression mandrel, which is a characteristic of the unconstrained section of the folded and compressed sleeve.

• «

In coreless sleeves, after folding and compression, further expansion occurs radially inward into the bore. This phenomenon is magnified in proportion to the extent to which the longitudinal extension of the section is limited.

The tendency of the folded and compressed casing to expand radially inwardly against the core creates an additional effect of the casing pleats being trapped on the outer surface of the core. By virtue of this advantageous effect, the tendency of the finished section of the folded and compressed casing to elongate longitudinally is substantially limited by the friction of the pleats against each other in combination with the frictional force between the pleats and the core, so that only minimal longitudinal restraint is required to maintain the dimensions of the section of the folded and compressed casing.

Example

A large diameter fiber casing of trade designation size 10 having a length of 76.22 m, a flat width of 19.18 cm and a wall thickness of 0.10 mm was folded using a folding agent. The casing had a moisture content of about 20% of the total weight of the casing. Mineral oil was used as a lubricant in accordance with conventional methods. Oil was used internally to reduce friction on the folding mandrel and oil was used externally to prevent damage to the folded casing and undesirable wear of the folding discs. About 28 mg of oil per 1 dm of casing surface was used internally, and about 15.5 mg of oil per 1 dm of casing surface was used externally. These amounts had no observable adverse effect on the properties of the finished section of folded casing. The casing was compressed from one end onto a hollow tubular core of high density polyethylene having a .14 .

internal diameter 9.53 cm and wall thickness 0.16 cm for a section of 58.42 cm. The product was manufactured on a folding machine with a floating folding mandrel in the manner described above, where the folded sleeve, after folding and slight compression, is moved onto a hollow tubular core arranged coaxially with the folding mandrel on its narrowed part, then it is additionally compressed and pulled off the mandrel.

Thus, a section of high density pleated casing with a core according to the invention was produced, which had a compression ratio of 130.4 and a compression efficiency of 0.757.

For comparison with the control sample, a standard, commercially available casing of the same size, 45.72 m long, was folded and compressed to a section length of 58.42 cm without the core, and a compression ratio of 78 and a compression efficiency of 0.390 per 92.075 mm inner diameter were found.

Other coreless control samples, which had a higher compression ratio and higher compression efficiency, were found to be non-functional products due to excessive reduction in the poison caused by radial increment.

Example 2

The fact that very high inward forces on the opening of the casing section develop as a result of folding was demonstrated by folding and compression experiments to a high compression ratio and high compression efficiency of size 25 samples (inflated casing diameter 21 mm) of a small-sized cellulose casing without fibrous reinforcement with a wall thickness of 0.0254 mm.

In these experiments, 5 samples of size 25 cellulose casings with a length of 25.61 m were folded using a folding device, with a twist being developed in the folded section, as described in patent document Sp. st. s. No. 3,397,069. The folded section was then compressed with a force of 194.6 kPa onto hollow tubular cores with wall thicknesses of 0.254 mm, 0.508 mm, 0.762 mm, 1.016 mm and 1.270 mm.

The core products were produced on the floating mandrel folding machine described above, except that during the final compression on the hollow tubular core 31 this was allowed to pass freely through the second clamp 29 (Fig. 3), so that the core was compressed simultaneously from both ends.

All hollow tube cores had an internal diameter of 1.30 cm and compression after folding was performed on a 1.27 cm diameter section of the folding mandrel onto which the core was slid. All samples had a moisture content of 16.5% of the total weight of the casings and mineral oil was used in

2 in an amount of 2.170 mg to 5.0 mg per 1 dm inside the casing and in an amount of 10.8 mg per 1 dm outside the casing as a lubricant. The amounts of lubricant are not critical, they represent the usual amounts for the folding machine used and the type of casing used.

The upper part of Table 1 shows the dimensions of the inner diameters of the cores immediately after removal from the mandrel and at least one day and up to 20 days later. The reduction in the diameter of the core hole was due to the large inwardly directed expansion force in the casing caused by the high compression ratio and high compression efficiency.

The amount of reduction in the inner core bore depends on the diameter of the tube as well as the magnitude of the inward forces and the strength of the core, i.e. large casings require a greater core thickness than small casings to withstand the same force per unit area.

The relatively high strength of high-density polyethylene allowed the 0.254 mm thick core to be compressed so that the inner diameter of the core of 12.2 mm was actually smaller than the opening of the sample without the core. However, the opening of the sleeve section was larger /12.2 + 2/0.254/ = 12.7/.

The lower part of Table 1 contains the values of the same size 25 folded and compressed sample on a 14.595 mm diameter mandrel, but without a core. Although a high compression ratio of 114.7 and a high compression efficiency of 0.63 were achieved with the conical folds, there was excessive reduction in the O.hole as determined by the drop test and this would be unacceptable for commercial practice. It would not be appropriate to directly compare these values with the values in Table 1 for the cored product because each cored sample was compressed on a mandrel that had an outer diameter that varied with the thickness of the core wall.

Table 1

Effects of inward compressive forces

Core wall thickness mm 0.254 0.508 with c With C Compression ratio of samples with core Compressed 133.4 .140.8 134.9 132.3 Downloaded 115.5 125.0 122.5 121.5 Later 114.8 121.3 116.8 118.8

Effective inner core diameter, mm

Downloaded 12.09 12.52 12.19 12.32 Later 11.81 12.19 12.11 12.32 Compression efficiency Later 0.55 0.68 0.58 0.70

0.762 1.016 1.270

With C With C With C 127.1 125.1 115.3 124.1 123.0 116.5 114.7 120.2 113.5 115.2 119.7 111.4 109.8 119.2 109.8 112.1 118.7 112.4 12.24 12.47 12.42 12.47 12.47 12.52 12.19 12.37 12.24 12.47 12.32 12.50 0.57 0.73 0.59 0.73 0.67 0.76

Coreless samples

Compression ratio for samples

Compressed

Downloaded

Later

Sample hole diameter

Retraction mm

Later mm

Compression efficiency later

136.5

111.7

90.1

13.51

12.93

0.44

141.5

125.4

114.7

13.18

12.37

0.63

In the experiments of folding the cases according to Table 1, two different fold angles were used. The designation S represents a fold angle of about 15°, the designation C about 45°. The S samples were folded with a folding device or folding discs similar to those described in the patent document Sp. st. s. No. 2 984 574.

The compression ratio of sample C without core is comparable to the 64.0 m long sample in Table 2, where the section of folded and compressed casing is unusable because it lacks cohesion.

The material used for the experiments in Table 1 was high density polyethylene. The cores were machined from thick-walled tubing and the resulting rough outer surface somewhat reduced the compression ratio that could be achieved. A look at Table 1 shows that for high density polyethylene cores there is considerable distortion of the housing bore as a final product even when the core thickness is large, such as 1.27 mm.

Table 1 also shows that for a constant compression force, in this example 183.5 kPa, the resulting compression ratio decreases with increasing core thickness, i.e., with increasing core outer diameter. In order to achieve maximum compression ratio, nozzle loading opening, and compression efficiency, core design must take into account core shrinkage due to high inward forces as well as the desired final core size, the reduction in compression ratio that would result from using excessive core wall thickness, and the cost of the core material.

Other core materials tested gave similar results in terms of core deformation. Cores made from acrylonitrile-butadiene-styrene copolymers performed satisfactorily at somewhat thinner wall thicknesses than high-density polyethylene cores, but these cores are less economical.

Example 3

The advantages of the high density cellulose core product of the invention, expressed in terms of compression efficiency and compression ratio, are demonstrated by folding and compression experiments to a high compression ratio and high compression efficiency of cellulose casing samples of size 25, i.e., an inflated diameter of 21 mm and a wall thickness of 0.0254 mm.

The moisture content of the casing was 16.5% of the total weight of the casing and mineral oil was used as a lubricant as in Example 2. Conventional folding means, similar to those described in the patent document Sp. st. a. No. 3,461,484, were used, and a twist was created in a section of the folded casing according to the patent document Sp. st. a. No. 3,397,069, after which each section was pressed onto a polypropylene tubular core with a tension of 20% by weight of talc for comparison with casings folded by the same methods but pressed without cores.

The high density cored cases were produced on the floating mandrel folding machine described above, except for the final compression on the core, with the tubular core 31 being allowed to slide freely through the second clamp 29 (Fig. 3) so that the case was effectively compressed from both sides.

To achieve more uniform compression along the entire length of the folded casing section, 24.38 m of casing was simultaneously compressed using incremental compression.

The coreless specimens and some cored specimens are designed to have a drop test diameter of 12.446. Other cored specimens were designed so that the tubular core served as a disposable charging nozzle. Under these conditions, the inner diameter of the core was equivalent to the inner diameter of a charging nozzle with an outer diameter of 12.7 mm, and the composite product is not subject to any special drop test requirements in relation to the charging nozzle.

For all samples, the composite casing was compressed to a final length of 508 mm. Ten casing samples were prepared for each cored and coreless configuration, ranging in length from 48.76 to 68.58 m.

The results of the experiments are summarized in Table 2. For products without cores with a length of 64.0 m and more, sections broke due to low cohesion and measurements by drop test after one week could not be performed.

For coreless products containing casing lengths of 57.15 m to 61.72 m, radial inward forces caused by casing enlargement after one week caused the composite section openings to shrink to a value at which they no longer passed the 12.446 mm diameter drop test.

For comparison purposes, the best folding method produced a coreless section of the folded casing 48.76 m long with an average compression ratio of 94.6 over 10 samples and an average compression efficiency of 0.491. The same folding method produced a folded and compressed high density product of the present invention designed to pass a drop test to a diameter of 12.446 mm. Thus, a product was produced whose inner core diameter was 59% of the diameter of the inflated casing. This product contained 60.96 mm of casing and had an average compression ratio of 116.46 over 10 samples and an average compression efficiency of 0.653.

These values therefore represent one preferred embodiment of the present invention, where based on a drop test, the core has an internal opening at least as large as the same housing would have if folded and highly compressed under the same folding and compression conditions without the core and to the same compression ratio.

The core hole diameter for products with a mean compression ratio of 116.46 was 12.6238 mm. In contrast, the coreless composite casing sections with compression ratios of 113.1 and 120.0 had hole diameters of 11.398 mm and 11.811 mm, respectively, significantly smaller than comparable products with a core.

A second series of high-density core samples was also produced, where the core in the composite product was intended to serve as a disposable charging nozzle with a throughput capacity equivalent to a standard charging nozzle with an outer diameter of 12.7 mm and an inner diameter of 11.074 mm.

Thus, a product was obtained whose inner core opening was equal to 51% of the diameter of the inflated casing. This product contained 70.104 m of casing and the mean compression ratio was 133.4, a compression efficiency of 0.617 for 10 samples.

To determine the quality of the folded and compressed products according to Example 3, with and without a core, a further test was carried out on the number of pinholes in the folded casing. Five sections from each type sample were tested for pinholes by filling the casing with water and increasing the pressure inside. The results shown in Table 2 show that the number of pinholes increases in proportion to the total length of the product without a core. In contrast, no pinholes were found in the products with a core.

In summary, Example 3 shows that it was not possible to produce a typical small diameter folded and compressed cellulose casing at a compression efficiency of at least 0.5 without unacceptably reducing the opening. In contrast, this was readily achieved with the product of the present invention, where a preferred compression efficiency of at least 0.6 was achieved.

Table 2

Small diameter bushings

Without core

With core

Diameter 12.45 mm according to drop test

Compression section diameter mm 14.60

Tube core outer diameter inner diameter mm Length

Diameter 12.45 mm according to drop test

14.48

12.45x12.95

For 12.7 m nozzle

12.45

12.45x11.18

cases m 48.77 57.15 59.44 61.72 64.00 66.29 68.58 0.57 60.96 70.10 Section length compressed case cm Compressed 48.23 48.26 48.26 45.72 45.72 43.81 43.81 50.49 49.68 Downloaded 51 .61 51.43 52.09 50.52 51 .46 50.59 51 .02 51.10 50.34 After a week 51.56 51 , 92 52.55 51.43 52.25 51.92 52.40 52.35 52.55 Compression ratio of the compressed section; cases Compressed 101.1 118.4 123.2 135.0 1 40.0 151.3 156.5 120.72 141.10 Downloaded 94.50 111 , 1 114.1 122.2 124.4 131 .0 134.4 119.28 138.55 After a week 94.60 110.1 113.1 120.0 122.5 127.7 130.9 116.46 133.40 Outer diameter of the section compressed casing mm Compressed N N N N N N N 24.59 25.02 Downloaded 24.00 24.13 24.38 24.71 24.84 25.58 25.73 24.61 24.81 After a week 23 , 93 2 3.82 24.13 24.13 24.38 24.69 24.94 24.38 24.99

Continuation of table no. 2

Without a core With the core Section Diameter 12.45 mm according to drop test Diameter 12.45 mm according to drop test For nozzle 12.7 m compression diameter mm 14.60 14.48 12.45

Diameter according to drop test mm

Downloaded 12.04 12.82 12.78 12.39 12.27 12.06 11.93 12.7 10, 92 After a week 12.55 12.19 ⁺ 11.93 ⁺ 11.8l ⁺ Break ⁺ From the quarry ⁺ Break ⁺ 12.62 10.79 Compression efficiency after a week 12.47 - - - - 16.59 15.67 Number of scoring holes in five samples 1 0 10 1 2 2 0 0

N values are not achievable ⁺ housing section is not functional

Another advantage of the high density casing with the core according to the invention is that it has a reduced tendency to damage the casing, i.e. the formation of pinholes, compared to the same casing folded and compressed under the same conditions but without the core.

This is because the core limits longitudinal stretching due to surface friction and less compression is required to achieve a given compression ratio compared to a composite section without a core. Since pinhole formation increases with increasing compression, the problem of casing damage can be reduced or eliminated with the product of the invention.

The core further allows for achieving and maintaining a fully compressed compression ratio and allows for higher compression ratios without pinhole damage.

This compression relationship between sections of folded cored and coreless casings was demonstrated in a series of tests in which 48.76 m long, size 25 fiber-free cellulose casings were folded and compressed equally with and without a core to a length of 381 mm and an initial compression ratio of 128.

After removal from the mandrel, the composite sections with and without cores were allowed to stretch for seven days without additional longitudinal restraint. At this point, the cored product had a longitudinal elongation of only 11.6 mm and a compression ratio after stretching of about 125, while the coreless product had a longitudinal elongation of 37.0 mm and a compression ratio of 117. Thus, for the desired final compression ratio of 125, a higher initial compression force would be required for the coreless sleeve section. The advantage of less tendency to damage the sleeve can be exploited in other ways. Once the user has determined the maximum compression force that can be applied without causing damage to the sleeve, the product can be formed with a higher compression ratio and compression efficiency.

Example 4

A series of experiments were carried out based on the contents of the above-mentioned British Patent Specification No. 1,167,377 to the applicant Viskase, Ltd. and a comparison was made with a section of high density cellulose casing according to the invention.

According to the aforementioned British patent specification, a polyvinyl chloride tube with an inner diameter of 40.97 mm and a wall thickness of 0.254 mm was used as a core, and a fiber-reinforced cellulose sleeve having an inflated diameter of 60.96 mm was folded by a folding means and then compressed to a length of 304.8 mm.

The inner diameter of 40.970 mm for the core and the size of 2.5 of the sleeve were chosen for this test because this diameter of polyvinyl chloride pipe was the smallest that was on the market at the time of the test. The product samples were made on a folding machine with a floating mandrel in the manner described above, where the folded sleeve, after folding, is transferred to a core arranged coaxially with the folding mandrel on its narrowed part, finally compressed in the manner according to Example 1 and pulled off the mandrel.

These samples had a moisture content after assembly of about 20% of the total weight of the casing and mineral oil was used as a lubricant internally at a rate of 31 mg per 1 dm of casing surface and externally at a rate of 16.585 mg per 1 dm of casing surface. The casing was manufactured in three different lengths, namely 22.86 m, 30.48 m and 38.10 m.

Various compression ratios were obtained for the compressed product. The resulting products were then drop tested to determine the internal hole. For a compression ratio of 75, the drop test gave a diameter value of 40.386 mm, i.e. a reduction in the hole diameter of 0.5842 mm.

For the sample with a compression ratio of 100, the drop test gave a value of 39.116 mm, a reduction in the diameter of the hole of 1.854 mm. For the compression ratio of 125, this was less than 38.1 mm. However, the core bulged at one end immediately after the product was compressed and removed from the mandrel. This shows the impossibility of producing a section of high-density cellulose pleated casing with a core according to the invention by the method according to the aforementioned British patent specification.

A sample with a casing length of 22.86 m would be usable on a 39.522 mm outer diameter charging nozzle, but the compression efficiency would be only 0.43. Samples with a casing length of 30.48 m had such a large reduction in the bore that they were not usable on this charging nozzle. Samples with a casing length of 38.10 m shrunk completely.

*

Example 5

Cellulose fibrous casings of similar size to the samples of the British Patent Specification in Example 4 were produced by the method of the invention and compared to samples without cores to examine the compressibility limits given by casing damage.

Size 2.5 casings with an inflated diameter of 60.96 mm and size 4 casings with an inflated diameter of 71.12 mm were folded using a folding device similar to that described in patent application No. 461,484. The moisture content of both size 2.5 and size 4 casings was 20% of the total weight of the casings.

_2

Mineral oil was used as lubricant, for size 211/2 cases 31 mg.dm inside, 15.5 mg.dm outside, for size 4 it was 26.35 mg.dm inside and 13.95 mg.dm outside. The products were compressed on polyvinyl chloride cores essentially identical to the cores used in Example 4. The samples were compressed to a length of 304.8 mm at a compression ratio of 150, which was the highest achievable compression ratio without damage for case size 2.5. All cases were designed to fit a 39.499 mm diameter charging nozzle. The cores used had an outer diameter of 43.51 mm and a wall thickness of 1.27 m. The samples equipped with cores were secured against longitudinal expansion by a clamp and the samples without cores were partially limited by cardboard cardboard.

The test results are shown in Table 3. The size 2.5 cored products had a slightly smaller resulting hole diameter for loading onto the charging nozzle than the coreless samples, even though the cored samples had a compression ratio of 138, while the coreless samples only had a compression ratio of 114.

In practice, a slightly smaller compression ratio would have ensured adequate fit of the charging nozzle to the core. Size 4 products with a core were functionally viable in terms of compression ratio after 15 days at a compression ratio of 138.46. Size 4 products without a core showed a reduction in the bore diameter to the limit of non-functionality after 15 days at a measured compression ratio of 128.48.

This Example 5 also shows, for fiber-reinforced casings, one preferred embodiment of the invention in which, based on a drop test comparison, the core has an inner diameter at least as large as a fiber-reinforced casing folded and highly compressed under the same folding and compression conditions and without a core and at the same compression ratio. * .

For example, for case size 2.5, the mean bore diameter of the case without a core was 39.116 mm, slightly smaller than the mean inner core diameter of 39.387 mm, for the case with a core, although the compression ratio was significantly higher in the latter case, 138 versus 114.

Similarly, for the size 4 case, the mean hole diameter of 39.387 mm was significantly smaller than for the core case, although the compression ratio was higher in the latter case, 138 versus 128.

A comparison of the above-described test results with those of Example V shows that British Patent Specification No. 1,167,377 does not provide guidance on the use of the core in a manner that would enable the three advantageous characteristics of the cellulose casing with the core of the invention to be simultaneously achieved, namely a high compression ratio, a high compression efficiency and limited deformation - reduction of the casing bore diameter.

Table 3

Fiber housing for 39.52 mm diameter charging nozzle

Tubular core

Outer diameter x inner diameter

Case size 2 1/2 Inflated diameter

60.96mm

Case size 4 Inflated diameter

71.12mm

With core

Without core

With core

Without core mm

Case length m Number of samples

Compression ratio of the compressed casing section /average height/ in 2 days in 15 days

Diameter according to drop test mm /mean value/ in 2 days in 15 days

43.51x40.97

45.72 45.72

17

138.46 114.28

138.46 113.92

9.7 2 39.72

9.29 39.17

43.51x40.97

45.72 45.72

17

138.46 130.91 138.46 128.48

40.20 39.37

40.18 39.29

Example 6

A series of tests were conducted using a folding device of the general type described in patent document Sp. st. a. No. 3,461,484 to Arnold, whereby a twist was created in the folded section of the casing according to patent document Sp. st. a. No. 3,397,069. In these tests, small diameter, high density cellulose casings with cores were produced, with various materials being used for the cores.

The core cases were manufactured on the floating spindle folding machine described above, except for the final compression of the case on the core, where the tubular core 31 was allowed to pass freely through the second clamp 29 (Fig. 3) so that the case was effectively compressed simultaneously from both ends.

The core materials used in these tests were polypropylene with 20% by weight fillers of talc, polystyrene, and high density polyethylene, with each core having an outer diameter of 12.7 mm and a wall thickness of 0.635 mm.

The casing used was made of cellulose, size 25 without fiber reinforcement and had a length of 60.96 m.

All samples had a moisture content of 16.5% of the total weight of the case before assembly and as

-2 -2 lubricant was used mineral oil from 2.17 to 3.1 mg.dm inside the housing and 10.85 mg.dm outside the housing.

The test results summarized in Table 4 show that the relatively low coefficient of friction of high-density polyethylene allowed the composite casing to be compressed to a significantly higher compression ratio than for other core materials.

From the experiments of Examples 2 and 6, it can be seen that the design of the core for the housing of the invention will be based on the properties of the core material, such as strength, modulus of elasticity and shear strength. These properties determine the core wall thickness required to withstand the internal expansion forces of the housing, which tend to deform the core and reduce its internal diameter.

The coefficient of friction of the core material determines the magnitude of the longitudinal compressive forces required to compress the casing to the compression ratio limits.

It is clear that many factors influence the choice of core material, in particular coefficient of friction, shear strength, modulus of elasticity, choice of extruded form, cost, formability, weldability and choice of reinforcing form. The final choice may vary for different applications.

For large diameter casings according to the present invention, preferred core materials are high density polyethylene and polyvinyl chloride.

Example 7

A series of tests were performed with high density casings with cores similar to those of Example 3 and Table 2. The only difference was that instead of final compression from both ends, compression was performed from one end of the casing as in the examples of Table 2 for the casing sections without cores, and the compressed folded sections were transferred to the core.

The results of these tests for high-density products with cores and size 25 cellulose casings are in Table 5 and can be compared to the results for the casings without cores in Table 2. The high-density product with a core designed to be 12.446 mm in diameter according to the drop test had a mean compression ratio of 15 samples of 129.2 and a mean compression efficiency of 0.67.

The high-density core product designed as a 12.7 mm outer diameter charging nozzle had a mean compression ratio for 15 samples of 140.1 and a mean compression efficiency of 0.64.

In summary, while Example 3 shows that it was not possible to produce a typical small folded and compressed cellulose casing with a compression efficiency of at least 0.5 when compressed from one end without unacceptably high aperture reduction, this was readily achieved with the product of the invention, where a preferred compression efficiency of at least 0.6 was achieved. No equipment was available for compressing casing sections from both ends without the use of cores.

Table 4

Small diameter bushings

Tubular core with an outer diameter of 12.7 mm and an inner diameter of 11.43 mm for use as a charging nozzle

Cellulose casing size 25 length 60.96 m

Core material

Talc-reinforced polypropylene

Compression loss of the compressed casing section

Compressed 149.3

Downloaded 139.5

After 1 week 137.1

Polystyrene

High density polyethylene

148.0 174.0 142.0 158.7 140.4 150.9

Diameter according to drop test mm

Downloaded After 1 week

10.67 10.92 10.92

10.67 10.92 10.92

Example 8

A series of tests were carried out with a cellulose casing without a fibre reinforcement of size 25 for the production of coreless and cored folded products at various compression ratios and these were tested by drop test /Fig. 8/ and for cohesion /Fig. 9/. All products were made from a casing length of 48.76 m and the compressed folded products had different lengths depending on the compression ratio.

The moisture content of the composite bushings was 16.5% of the total weight of the bushings and mineral oil was used as lubricant _2 in an amount of 2.17 to 3.1 mg.dm on the inner surface and _2

10.85 mg.dm on the outer surface during case folding.

For folding the cases, a folding device of the type described in the patent document Sp. st. a. No. 3 461 484 was used, and the case was compressed in the usual way, while a twist was created on it according to the patent document Sp. st. a. No. 3 397 069. The compression was carried out on a folding machine of the floating mandrel type /Fig. 3/.

After compression, the section of the folded and compressed casing was transferred to a tubular core. This was made of polyvinyl chloride tube having an outer diameter of 14.224 mm and an inner diameter of 12.852 mm. For one group of tests, the compression mandrel section had a diameter equal to 14.605 mm, for another, a diameter of 15.113 mm.

Drop tests and cohesion measurements were performed for both coreless and cored products and the compression ratio seven days after section compression and mandrel removal. The results are summarized as a function of compression ratio in Figures 8 and 9.

In Fig. 8, the x-axis plots dimensionless values for cores made with non-filamentous casings with a compression ratio of 25, and the y-axis plots drop test data in mm.

Fig. 8 shows that the drop test diameter for coreless sections produced on the compression part of the mandrel with diameters of 14.605 mm and 15.113 mm changes continuously with increasing compression ratio in the compression ratio range of 95 to 120.

Since the minimum bore diameter for a size 25 sleeve with an inflated diameter of 21.082 mm is 12.446 mm, which corresponds to the horizontal dashed line, the maximum usable compression ratio for a mandrel with a diameter of 14.605 mm is equal to 99.

Table 5

Small diameter bushings

With core For diameter 12.45 mm according to drop test For single-use charging nozzle equivalent to 12.7 mm charging nozzle Section diameter, compression mm 14.60 13.00 Pipe core outer diameter x inner diameter mm 14.22 X 12.95 12.70 x 11.43 Case length m 60.96 60.96 Length of the compressed sleeve section mm Compressed 431.8 381.0 Downloaded 473.20 434.34 In 1 week 471.93 435.10 Compression ratio of the compressed sleeve section Compressed 141.2 160.0 Downloaded 128.8 140.3 In 1 week 129.2 140.1 Outer diameter of the compressed sleeve section mm Compressed N N Downloaded 24.96 23.85 In 1 week 24.87 25.06 Drop test diameter mm 12.64 10.92 Downloaded 12.64 10.92 In 1 week 12.54 10.74 Compression effectiveness in 1 week 0.67 0.64

N values were not accessible

By using a larger diameter mandrel of 15.113 mm, the minimum housing bore diameter can be achieved at a somewhat higher compression ratio of 103, but this increases the likelihood of damage to the housing by pinholes.

Significantly larger diameters of the compression part of the mandrel, above 14.605 mm, for size 25 casings increase the probability of jamming on the mandrel, more frequent interruptions of operation and a higher amount of rejects. Considered differently, it is obvious that for optimal trouble-free folding of casings of a certain size, it is necessary to choose the smallest mandrel diameter for which the desired casing hole diameter is achieved.

In contrast to the above-described limitation of the compression ratio for the composite section of the coreless sleeve to a value of 99 in order to achieve the required hole size, Fig. 8 shows that for the size 25 sleeve with a core, the diameter according to the test was constant with increasing compression ratio up to a value of 124 using the same mandrel diameter of 14.605 mm.

As the compression ratio is further increased, the inner diameter of the core begins to decrease due to the excessive inward radial force exerted by the folded section of the casing. The value of 124 therefore represents a practical upper limit of the compression ratio for this particular embodiment, where the diameter of the inflated casing is about 21.082 mm, the compression ratio is greater than 100, and the drop test diameter is 12.446 mm.

It has unexpectedly been found that when the compression ratio of the composite sections of cellulose casings without fibrous reinforcement and without a core is in the range of the compression ratio achievable with the cored products of the invention, then the cohesion of the cored products decreases rapidly as the compression ratio increases.

This is different from what was expected, because at lower compression ratios used in practice, it is known that the cohesion of the same section of coreless casing progressively increases with increasing compression ratio.

This unexpected finding that cohesion decreases with increasing compression ratio for folded sections of coreless casings is illustrated in Fig. 9 for a size 25 casing.

In Fig. 9, the x-axis plots dimensionless values for cores formed with non-fibrous casings with a compression ratio of 25, and the y-axis plots cohesion as a dimensionless number.

It is clear from Fig. 9 that for a mandrel with a diameter of 14.605 mm, the cohesion changes from an almost constant value of 5 at a compression ratio of 100 to a low value of 1.5 at a compression ratio of 125. This is slightly higher than the minimum practically acceptable cohesion of 1.2 and is significantly lower than the recommended cohesion of 2.5.

In contrast, in the high density folded casing with the core of the present invention, the cohesion is not limited because the compressed folded casing is supported by the outer surface of the core with which it is in contact.

Although not fully explained, it is believed that the above relationship between compression ratio and cohesion for coreless cellulose casing sections is related to the degree of compression of the casing pleats. A possible explanation is that in the region of lower compression ratios, compression of the casing pleats produces a closer fit of the individual cones, thereby increasing the contact area between adjacent cones and thus increasing cohesion.

This possible explanation is in agreement with the experimental observation that as the compression ratio of coreless cellulose casing sections increases, the cohesion initially increases to a maximum value and then decreases more rapidly.

A possible explanation is also in agreement with the experimental observation that larger diameter casings have higher cohesion at higher compression ratios than smaller diameter casings /Fig. 11/.

AND

This may be due to the larger areas of the adjacent cones in the larger diameter casings. The results for the size 25 casing of length 48.76 m, which are shown in Figs. 8 and 9, also meet the requirement of the invention that the casing have a compression efficiency of at least 0.50 and that its compression ratio and compression efficiency are higher than those of a casing of the same length folded and compressed under the same conditions but without a core.

The characteristics of the samples after seven days, /a/ the cored product that met the minimum diameter requirement of 12.446 mm according to the drop test, /b/ the coreless product that was folded and compressed under the same conditions as sample /a/, and /c/ the coreless product with the same diameter according to the drop test but with the highest compression ratio, were as follows:

Sample Drop test Compression ratio Compression efficiency /a/ with a nucleus 12.7mm 124 0.66 /b/ without a core 11.684 mm 116 0.54 /c/ without a nucleus 12.7mm 98 0.44

These values show that the drop test diameter, compression ratio and compression efficiency of sample /a/ were all higher than those of sample /b/. In addition, sample /b was not an acceptable product because the casing section grew inward into the hole to such an extent that sample /b/ did not meet the drop test condition.

Due to this defect in the hole size of sample /b/, sample /c/ was the best coreless sample that would perform the same function as sample /a/ with core. On this basis, sample /a/ represented an improvement of 26% in compression ratio and 50% in compression efficiency.

Example 9

A series of tests similar to those of Example 8 were conducted with size 25 casings, with three different sizes of cellulose casings without fibrous reinforcement, both smaller and larger. These were size 17 with an inflated diameter of 15.494 mm and a wall thickness of 0.0254 mm, size 18.542 mm with an inflated diameter of 0.0254 mm, and size 27 with an inflated diameter of 22.606 mm and a wall thickness of 0.0254 mm.

The difference from Example 8 is that instead of using sleeves of the same length and producing sections of folded and compressed sleeves of different lengths according to the compression ratio, in these tests the lengths of the sleeves were varied and were compressed so that the sections of folded and compressed sleeves had the same final length after seven days from removal from the mandrel. For size 17 this final length was 406.4 mm, for sizes 21 and 27 it was 520.7 mm.

Another difference between these tests and the tests of Example 8 is that no core products were prepared from the size 17, 21 or 27 casings. However, in a similar test, a high density product was prepared from the size 21 casing and had the following characteristics: compression ratio 119.8, compression efficiency 0.66 and core inner diameter 10.7188 mm.

This cored product was therefore suitable for use on the 10.175 mm outer diameter charging nozzle under consideration. As can be seen from Figs. 10 and 11, which show the characteristics for a section of a size 21 case without a core, these cannot be achieved by similar products according to the prior art.

Apart from the differences described above, the coreless sections of the 17, 21 and 27 size folded sleeves were manufactured in the same manner as the 25 size sleeve sections. After being removed from the mandrel and stored for seven days without length restriction, the sleeve sections were subjected to a drop test and cohesion measurements. The results are summarized for the drop test in Fig. 10 and for cohesion in Fig. 11 as curves plotted against compression ratio.

In Fig. 10, the x-axis plots the dimensionless values for cores made with non-filamentous casings, and the y-axis plots the drop test data in mm. The straight lines represent the compression ratios 17, and 27.

In Fig. 11, the x-axis plots the dimensionless values for cores made with non-woven sleeves, and the y-axis plots the cohesion as a dimensionless value. The curve represents a compression ratio of 27, while the straight lines represent compression ratios of 17 and 21.

It can be seen from Fig. 10 that, similarly to the case of the size 25 bushings, the diameter values according to the drop test decrease with increasing compression ratio for all three tested bushing sizes at essentially the same rate. For the case of the size 17 bushing, the minimum acceptable diameter according to the drop test is 9.114 mm, see the horizontal dashed line, so that according to the drop test, the maximum compression ratio achievable for the section of the bushing without a core according to the prior art is equal to 80.

Similarly, for a size 21 case, the minimum acceptable drop test diameter is 10.414 mm, so the maximum compression ratio achievable for a coreless case section according to the prior art is equal to 98.

Finally, for case size 27, the minimum acceptable drop test diameter is 13.642 mm, so the maximum compression ratio achievable for a coreless case section according to the prior art is equal to 130.

The cohesion versus compression ratio curves in Fig. 11 all show the aforementioned unexpected relationship of decreasing cohesion with increasing compression ratio in the upper compression ratio range for all case sizes.

For size 17, the cohesion is low throughout the compression ratio range of 60 to 125, considering the minimum acceptable value of 1.2 shown by the horizontal dashed line. For size 17, the maximum achievable compression ratio according to cohesion is also 80 for the coreless folded casing. For size 21, the cohesion is also low throughout the tested compression ratio range, and for the minimum acceptable cohesion of 1.2, the maximum achievable compression ratio is 102.

¹ The above-mentioned full range of cohesion at increasing compression ratio is shown for coreless casing size 27. For compression ratios up to 120, cohesion increases with increasing compression ratio, but from compression ratio 122 onwards it decreases at an approximately constant but rapid rate.

It is apparent from Figures 10 and 11 that drop testing and cohesion constitute significant limitations for the use of high compression ratios in the sections of the prior art coreless folded cellulose casings of sizes 17, 21 and 27.

The product of the present invention can in all cases provide higher compression ratios with acceptable casing hole sizes and higher cohesion and with less tendency for casing damage by pinholes.

More specifically, a size 17 folded case with a core according to the invention with an inflated diameter of 15.494 mm and a drop test diameter of at least 9.144 mm has a compression ratio higher than 80. Also, a size 21 folded case with a core according to the invention with an inflated diameter of 18.542 mm and a drop test diameter of at least 10.414 mm has a compression ratio higher than 98. Finally, a size 27 folded case with a core according to the invention with an inflated diameter of 22.606 mm and a drop test diameter of at least 13.642 mm has a compression ratio higher than 130.

Example 10

The compression ratio and compression efficiency of medium-sized fiber-reinforced folded cases were investigated in a series of cored and coreless case tests to determine the advantages of the products of the invention. Size 43, 47 and 60 cases having flat widths of 58.42 to 83.82 mm were used to produce folded and compressed case sections for fitting to a charging nozzle with an outer diameter of 27.2542 + 0.127 min.

Furthermore, cases of sizes 70, 80 and 100 having flat widths from 95.25 to 139.70 mm were used to fit a charging nozzle with an outer diameter of 39.5224 t, 0.127 mm. Cases with and without cores were produced for all sizes, the wall thickness of all samples was 0.078 74 mm.

The moisture content of the composite bushings was 20% of the total weight. The lubricant used was

- 2 —2 mineral oil in the amount of 6.82 mg.dm for the inner surface and in the amount of 4.65 mg.dm for the outer surface of the sleeves. The swollen diameters of these fiber reinforced sleeves were as follows:

Size Bloated stomach 43 37,592 47 40,355 60 56,802 70 60,629 80 70,403 100 88,519

In these tests, various lengths of casing were compressed into sections of essentially the same length for all compression ratios of a given casing size. These section lengths were 266.7 mm for size 43, 254 mm for size 47, 228.6 mm for size 60, and 304.8 mm for sizes 70, 80, and 100.

All of the sample casing sections were made on the floating mandrel folding machine described above. The folding means was of a type commonly used in practice similar to that described in U.S. Patent No. 3,461,484.

Samples were prepared under each condition. The coreless samples were folded and compressed from one end on a mandrel to the maximum compression ratio that could be achieved without damaging the casing, as well as to lower compression ratios.

The maximum compression ratio without damage was determined by hole tests by filling with water and increasing the pressure inside the casing. If damage was found, additional samples were made at a slightly lower compression ratio and tested by filling with water at the point holes. The procedure was repeated until the compression ratio without damage to the casings was achieved and this was declared the maximum compression ratio.

After compression on the mandrel, the samples of sizes 43, 47 and 60 without cores were transferred to a small diameter plastic tube of 27.94 mm using a folding machine for handling. After 1 hour, they were removed from the tube and placed in a sieve. This was clamped at both ends.

This arrangement slightly limits the longitudinal expansion of the sleeve section. The sleeve sections of sizes 70, 80 and 100 without cores were transferred from the folding machine directly into a polyvinyl chloride film wrapper, which formed a .elmi limited restriction of the ends of the sleeve section. These methods; are common in practice. The cores of the sleeve sections were made of rigid polyvinyl chloride. For the sleeves of sizes 43, 47 and 60 the outer diameter of the core was 32.242 mm and the core wall thickness was 0.635 mm. For sizes 70, 80 and ]00 the outer diameter of the core was 43.51 mm and the core wall thickness was 0.635 mm.

After folding, the core samples were moved longitudinally from the core mandrel aligned with the folding mandrel around its tapered portion in the manner described above and illustrated in Fig. 3. The folded sleeve was then compressed to the desired compression ratio section from one end and withdrawn.

The cored samples were compressed to compression ratios equal to the compression ratios of the coreless samples.

After withdrawal, the products were provided with means equivalent to the retaining discs 35 and flange 39 of Fig. 6 at both ends of the casing to maintain the compressed length of the section for several days of storage.

This end restraint was not applied to coreless samples because these would either bulge or expand inward to a size that would prevent their fitting onto the appropriate charging nozzle. The screen or plastic film wrapping used on coreless products did not significantly limit their longitudinal expansion.

The section lengths were measured for both coreless and cored specimens before compression and again after seven days of storage. The results of these measurements are shown in Fig. 12 for sizes 43, 47 and 60 fiber-reinforced casings and in Fig. 13 for sizes 70, 80 and 100 fiber-reinforced casings, with compression ratios plotted as a function of the flat width of the casings.

In Fig. 12 and Fig. 13, two scales are arranged on the x-axis. The upper scale shows the flat widths of the fiber-reinforced casing, in mm. The lower scale shows dimensionless integers corresponding to the casing sizes. The y-axis shows the compression ratio, which is a dimensionless number.

In both Fig. 12 and Fig. 13, the lowest curve represents the folded compressed section without the core after seven days of storage. The middle curve represents the folded and compressed section with the core after seven days of storage, and the highest curve, indicated by the dashed line, represents the folded and compressed section with the core immediately after compression.

It is mentioned because it represents a condition achievable according to the invention which cannot be achieved according to the prior art with a coreless casing section. That is, by securing the opposite ends of the cored article after compression but before withdrawal, for example by means of restraints, the initial compression ratio can be maintained without losing other important parameters.

For example, there is minimal reduction in the opening because the compressed section of the sleeve is limited inwardly by the core. If limiting means were used in the longitudinal direction of the section of the sleeve without the core, immediately after removal from the mandrel, the initial maximum compression pressure was maintained, but the opening was reduced compared to the case where the section of the sleeve was left without length limitation.

Since in practice the smallest possible diameter of the collet is used to obtain optimum results, for the reasons stated above, radial expansion of the sleeve section inwards would result in a reduction of the bore to a size that would be too small to fit the respective charging nozzle.

Fig. 12 shows that based on a comparison of the compression ratio values after seven days for sizes 43 to 60 fiber-reinforced pleated casings, with and without cores, see the two lowest curves, the smallest improvement is for the size 43 casing, the difference here is 78 minus 60, or a 30% improvement in compression ratio when using a core.

The greatest improvement is in size 60, where the difference is 129 minus 79, or 63%, with the core. The maximum possible improvement based on comparing the compression ratio after seven days of the coreless case, corresponding to the lowest curve, with the initial highest compression ratio, corresponding to the highest dashed curve, is significantly higher.

AND

For example, for size 43 the difference is 97 minus 60, or a 62% higher compression ratio, for size 60 the difference is 146 minus 79, or 85%.

Comparison of compression efficiencies and compression ratios for sleeve sections with fibers of sizes 43, 47 and 60 with and without cores of the nuclei described in Example 10 is this: Efficiency compression and ratio compression Size Without cores With the core With the core cases in 7 days in 7 days initial 43 0.54 /60/ 0.74 /78/ 0.78 /82/ 47 0.53 /66/ 0.76 /95/ 0.81 /102/ 60 0.45 /7 9/ 0.75 /130/ 0.85 /147/ Fig. 13 shows that based on : comparison of values ratio compression after 7 days for cases

with fiber reinforcement sizes 70 to 100 without cores and with cores, the improvement in compression ratio is smaller than with sleeves sizes 43 to 60, but equally significant.

The smallest improvement is for case size 80, where the difference is 166 minus 154, or 8%. The maximum possible improvement based on comparing the compression ratio after seven days for the be2 core case with the initial maximum compression ratio for case size 80 is 180 minus 154, or 17%.

A comparison of the compression efficiencies and compression ratios for the 70, 80, and 100 size fiber sleeve sections with and without cores described in Example 11 is as follows:

Compression efficiency and compression ratio

Case size Without a core With the core in 7 days With the initial core in 7 days 70 0.66 /129/ 0.77 /141/ 0.82 /150/ 80 0.63 /154/ 0.71 /166/ 0.77 /180/ 100 0.50 /167/ 0.59 /187/ 0.70 /220/

Although cohesion is also important in fiber-reinforced cellulose casings, it is not as serious a problem as it is in smaller diameter unreinforced cellulose casings. This is partly because the fiber reinforcement makes the casings stronger, and also because there are some differences in the loading devices for the two types of casings.

Small diameter cellulose casings are generally loaded on fully automated machines operating at high speed, where the next section of casing to be used is automatically fed to the loading position when the previous section of casing has been exhausted.

Low cohesion can cause section breakage, which in turn can cause the casing to break or tear during insertion or rotation of the automated charging nozzle. When this happens, a significant amount of charging emulsion is dispersed into the surrounding area before the equipment can be stopped and significant time is required to clean the machine and remove the broken casing.

In contrast, when using larger diameter fibrous casings, the machine speed is usually lower and the next section of casing is fed in manually by the operator. When a casing rupture occurs, which is less often due to the fibrous reinforcement, the equipment can be stopped before a significant amount of food emulsion has been released and the dead time is shorter.

Example 11

Prior to the invention, the applicant, Union Carbide Corporation, had developed and sold a machine for loading boneless whole hams into large diameter fiber-reinforced cellulose casings of the type described above. It was proposed to use a composite casing with a calibration disc inserted into one of the expanded ends of the coreless section of the casing.

At the end of the machine design, the necessity of a maximum opening of the charging nozzle was identified, as well as a limitation on the size of the charging nozzle given by the maximum obtained opening of the section of the folded case.

To obtain the maximum size of the charging nozzle, its wall thickness was reduced to the minimum permissible with regard to strength, the length of the case was necessarily and undesirably reduced from 60.96 m to 45.72 m, and the folding conditions were optimized for the largest achievable opening.

Also, the wall thickness of the draw sleeve and the clearance at the charging nozzle were necessarily and undesirably limited to the minimum acceptable dimensions.

The result of this effort was the use of the highest attainable state of folding and the use of a charging nozzle with an internal diameter of 85.725 mm. The original machine is described in Belgian patent document No. 888 526. A considerable number of these machines were installed in meat processing plants, but they were found to be unsuitable for most applications.

It has been observed that the extreme elongation of ham pieces as they pass through the loading nozzle and the subsequent expansion during loading into the casing causes the surface fat to curl into the inside of the loaded encapsulated hams and causes a grainy arrangement of lean muscle fibers.

The system was not recognized by manufacturers as equivalent to manual loading, and demand for these machines declined.

Tests were conducted in the applicant's laboratories using larger loading nozzles and uncollated cases. These tests ultimately showed that a larger diameter loading nozzle would solve this problem and that hams loaded with the larger loading nozzle were of the same quality as hams loaded by hand.

At that time, the applicant began to develop a high-density core sleeve section according to the invention. Development work showed that the use of a high-density core sleeve section according to the present invention as a charging nozzle resulted in an increase in the inner diameter of the charging nozzle to 95.7 mm. This increase was partly due to the omission of the pulling sleeve in the said machine. The pulling sleeve was replaced by a flexible retaining device.

As a result of these modifications to the above machine, the diameter of the loading nozzle opening has increased from 85.725 mm to 95.7 mm for size 10 fiber cases. This represents an increase in diameter of 9.525 mm or 11.1%. This increase in diameter results in an increase in the inner diameter of the loading nozzle of 23.5 in.

Of this 23.5% increase in the cross-section of the charging nozzle, 7.5% is due to the elimination of the prior art pull sleeve and 16.0% is due to the use of a high density cored housing according to the invention.

By modifying the charging nozzle and using the cored sleeve section in this manner, it was possible to increase the compression ratio of a size 10 fiber sleeve from 78 to 130, a 67% increase. The compression efficiency was also increased from 0.39 to 0.76, and the sleeve length was increased from 45.72 m to 76.20 m. Example I illustrates the use of the cored sleeve section in this improved machine.

This example also demonstrates the advantageous formation of a folded casing with a core, where based on the hole comparison, the core has an opening at least as large as the casing would have if folded and compressed under the same folding and compression conditions without the core and to the same compression ratio.

In a special case, based on a size 10 fiber casing, a modified cored casing machine uses cores with a bore of 95.7 mm, while the bore of the coreless casing was 92.075 mm when folded and compressed to a compression ratio of 78. The core used for this casing size is made of high density polyethylene and has a wall thickness of 1.5748 mm.

After the modifications were made, the modified loading machine was returned to the meat industry, which was not satisfied with the original design of the machine, but has now accepted it as a significant improvement in the packaging of hams in casings according to the present invention.

Ten months after the introduction of the new machine, twenty were already in operation and others were installed in food industry companies for loading meat products. The original machine was withdrawn from the market and replaced by a new one.

The invention thus represents, as explained above, a significant advance in the art. The greater length of the casing in a folded section of a given length allows for longer production periods. The higher compression efficiency gives a more favorable combination of high compression ratio and large bore, which can maintain or improve charging characteristics while achieving longer production periods.

The present invention completely eliminates the problems of cohesion and enlargement of the compressed casing section, which have heretofore caused difficulties to manufacturers and users of small diameter casings. The wetted embodiment of the product according to the invention is particularly advantageous because high compression ratios cannot be achieved with casings which are wetted by the user before loading.

This is because the folds preventing water from entering the housing wall are tightly fitted together and proper wetting could not be carried out in a time acceptable for operational reasons.

It should be noted that comparing the hole diameters of cases that have been folded and compressed, without cores or with cores, is advisable to do at least one week after production.

It is obvious that many variations of the present invention can be made without departing from the scope of the invention. The above description is therefore only an example of an embodiment, without limiting the scope of the invention.

Claims (14)

SUBJECT OF THE INVENTION CLAIMS 1. A composite tubular casing comprising a tubular core resistant to deformation and shrinkage of the core aperture extending inwardly of the casing and a moistened cellulosic food casing having a moisture content of at least 13% of the total casing weight, preferably a moisture content of 16 to 35. % of the total weight of the sleeve folded and compressed on said tubular core with a compression ratio of at least 70 and a compression efficiency of at least 0.50. Housing according to claim 1, characterized in that the cellulosic food casing is provided with a fiber reinforcement. 3. The sleeve of claim 1 comprising a tubular core with an inner diameter equal to or greater than that of the sleeve folded and compressed under the same folding and compression conditions, but without the core. Housing according to claim 1 or 3, characterized in that it comprises a tubular core with a wall thickness of at least 0.5 mm. 5. A container according to claim 1 comprising a food container having an inner diameter equal to at least 50% of the inflated diameter of the container. 6. A method according to claim 1, wherein the cellulosic food casing has a moisture content of at least 13% of the total weight of the casing, the inner surface of the perimeter being threaded onto one end of a mandrel having a reduced diameter at the other end. The mandrel is folded to the end of the mandrel of reduced diameter, a hollow core resistant to deformation by shrinkage due to expanding force directed into the sleeve due to its compression is slid, the composite sleeve is linearly displaced along the mandrel to the outer surface of the coaxially mounted core. 7. A method according to claim 1, wherein the cellulosic food casing has a moisture content of at least 13 and the total weight of the casing, the inner circumference of the casing is threaded to one end of the mandrel, the casing is compressed and compressed, wherein the hollow core resists deformation and diameter reduction due to inward expansion of the sleeve due to its compression, and the composite and compressed sleeve is linearly moved from the other end of the mandrel to the outer surface of the sleeve to compress. 8. A method according to claim 1, wherein the cellulosic food casing has a moisture content of at least 13% of the total weight of the casing, the inner periphery of the casing is slid onto one end of the mandrel, the casing is collapsed on the mandrel. Resistant to deformation and diameter reduction due to the inward expansion force of the sleeve resulting from its compression, the composite sleeve is moved from the other end of the mandrel to the outer surface of the hollow core, and then the composite sleeve is further compressed. 9. The method of claim 8 wherein the composite food cellulosic sheath is transferred to a second position before being transferred from the second end of the mandrel to the hollow core. 10. A method according to claim 1, wherein the cellulosic food casing has a moisture content of at least 13% of the total casing weight, forming a hollow core resistant to deformation and diameter reduction due to the expanding force directed towards the interior of the casing as a compression. the inner circumference of the hollow core is longitudinally slid onto the outer surface of the mandrel, the inner surface of the sheath is longitudinally slid onto the outer surface of the hollow core, the casing is folded on the hollow core and the mandrel, and then the casing is hollowed: pulls with core with thorn. 11. A method according to claim 1, wherein the cellulosic food casing has a moisture content of at least 13% of the total casing weight, the inner surface of the casing is applied to one end of the mandrel, the casing is folded on the mandrel, and the casing is folded. For example, a hollow core is formed on the mandrel to resist deformation and diameter reduction due to the expanding force directed towards the inside of the sleeve as a result of its compression. 12. A method according to claim 1, wherein the cellulosic food casing has a moisture content of at least 13% of the total weight of the casing, the inner surface of the casing is applied to the first end of the mandrel, the casing is folded onto the mandrel. A hollow core is formed to resist deformation and diameter reduction due to inward expansion of the sleeve due to its compression, the composite sleeve carried on the mandrel is moved to a second position, the composite sleeve is transferred from the first end of the mandrel to the outer surface of the sleeve and then . Method according to claim 8 or 12, characterized in that the hollow core carries a second mandrel. 14. The method of claim 12 wherein the partially compressed sleeve is transferred to the hollow core and the second mandrel.