IE75384B1 - A method of producing a batch of rolls of compressible materials and an apparatus for carrying out the said method - Google Patents

Description

A METHOD OF PRODUCING A BATCH OF ROLLS OF COMPRESSIBLE MATERIALS AND AN APPARATUS FOR CARRYING OUT THE SAID METHOD The present invention relates to conditioning of compressible material, and, in particular, of insulating felts of glass wool or other mineral wool, and is directed more particularly at the production of a batch which can be loaded on pallets, of reduced bulkiness facilitating the transport and the storage of these products .

Light fibrous insulating materials are generally conditioned in the compressed state in the form of rolls closed by unitary packagings of the paper band or plastics material envelope type, essentially based on polyethylene, heat shrunk.

To reduce the cost of transport operations, in particular during loading and unloading, and to simplify storage, these rolls are usually assembled in batches on pallets. In practice, the measurements thereof must be compatible with the measurements of the transport means, lorries or, more often, railroad wagons. These latter also restrict the total height of the batch which has been put on pallets, which must, therefore, finally, comply with a very strict restriction which involves a reduced number of rolls.

On the other hand, and without surrounding the batch with rigid panels in such a manner as to form protecting cages providing the definition of volume allocated to the rolls - a solution a fault of which is obviously to increase, considerably, the cost of the batch these rolls must, necessarily, be mounted on end, in such a manner that the weight of the rolls forming the upper layers acts perpendicular to the radial compression force exerted during the forming of the roll. In these conditions, increasing the number of rolls per batch on a pallet does not seem to be possible except by reducing the diameter of the rolls, thus by increasing the rate of compression during the rolling. This solution, which is already very widely practised, is, however, restricted by the limit of the elastic compressibility of the material; it should be remembered that the insulating capacity of the fibrous material is a direct function of the thickness thereof, and that it is thus not a question of accepting any damage in this area.

It has likewise been proposed in European patent application EP-A-275 473 to band a group of five or nine rolls using a sheet of plastics material, to cover the group that has been insulated in this manner by means of an device which evacuates one part of the air imprisoned between the coils of the rolled felt and between the rolls. The evacuation of this volume of air thus allows the rolls to come closer together, the batch being kept permanently in this reduced state by means of wrapping with straps. A process of this type, however, involves a relatively complex installation and, above all, requires a second phase of wrapping with straps in the case where sets need to be superimposed.

The invention indicates a novel solution for compressing a batch of rolls of compressible material, and, in particular, of insulating fibrous material, or, which, of course, amounts to the same thing, for increasing the number of rolls per batch, and to do this whilst preserving the quality of the material, whilst being careful, in particular, not to create permanent deformations which remain when the rolls are unpacked, even after a relatively long duration of storage, for example of several months .

To this end, there is proposed a process consisting in rearranging the rolls by the temporary application of a superpressure. More precisely, the press according to the invention comprises the following stages: ties, forming modules each formed of a layer of rolls placed side by side, in contact with one another; superimposing several modules in a stack, the rolls being disposed in a layered manner (see EP-A-220 980, constituting the closest prior art), said process being characterised by the following supplementary stages: compressing this assembly of superimposed modules in the direction in which the modules are stacked, the compression reducing the thickness of the assembly to a height which corresponds to a rate of compression of the felt which constitutes the compressible material which is greater than the rate of compression corresponding to the elastic limit thereof; cessation of compression in order to allow this assembly to loosen; positioning of ties to control the stack of modules at the dimensions obtained.

Furthermore, before positioning these the stack may be turned by 90° in such a manner that the rolls are in an upright position.

The temporary vertical compression may be very substantial, and in any case corresponds to a rate of compression which is greatly superior to the limit of elastic compression of the material which, it will be remembered, is already very strongly compressed during the phase of forming the roll. The compression may for example, reduce, temporarily, the height of the batch to a height of between 50% and 80% of the initial height, the duration of the compression phase being adjusted in consequence and being shorter the higher is the temporary compression which is exerted.

As soon as the compression is interrupted, the rolls regain a part, but only a part, of their initial thickness. However, the increase in thickness does not manifest itself as damage of the compressible material. Examination of the rolls shows that, in fact, this reduction of the height of the batch is not due to a new compression of the batch, but to a rearrangement of the rolls, which change from an initially cylindrical shape to a parallelepipedal shape, which shape leads to more compact stacking. In a surprising manner, it has become clear that this parallelepipedal shape absolutely does not restrict the quality of the final product and that the unpacked product does not retain any trace of its conditioning.

The stack must be retained at the dimensions obtained after it has been released; for this purpose, a hoop may be used which positions two or three ties, for example of plastics material. Another solution is to perform wrapping with a strip of a plastics material which can be stretched, the batch thus being protected from bad weather and, in consequence, may be stored in the open air.

The stack of rolls is, preferably, restricted to three layers, but several batches, two at the very least, may be superimposed before the stage of positioning the ties, provided that care is taken to ensure that the axes of the rolls are well aligned to prevent the weight of the upper layers damaging the lower layers.

The vertical compression cannot be completely compensated by a displacement of the end rolls of each layer, and these latter must themselves be held, except if the compression drives in the edge thereof. To achieve this, a prewrapping of the stack of rolls with strips might be performed, prior to the application compression. Another solution is to band the assembly of the rolls forming a layer, which has the advantage of creating modules, of, for example, 4 to 6 rolls, which are prepackaged and which may thus be sold in sets. In this case, the end faces of the rolls are not retained during the compression, but, rather, in the condition of use a material which has a certain elasticity is used to belt the modules of the rolls, a fact which, in practice, does not pose any problems.

Furthermore, belts of this type of thermoplastic material can contribute, between them, rendering the modules integral with one another before turning them, this rendering integral being obtained by heating the belts - for example by blowing with hot air - during the phase of releasing the stack. These modules may likewise be rendered integral with one another by means of glued or adhesive strips.

A device which is suitable for performing the process according to the invention and comprises a station for stacking the layers of rolls, a vertical compression station, optionally a station for rotating the stack by 90°, a station for positioning the ties and a transporter for displacing the stack from one station to another.

The compression station may, for example, be formed of a presser plate suspended by means of a block and pulley above a conveyor belt acting to introduce and remove the stacks. A compression station of this type may be inserted into an existing packaging line without displacing it. In another variant, the compression station is formed of a hydraulic table which raises the batch to press it against a flat, fixed presser plate, the table thus replacing the conveyor.

In a particularly preferred embodiment of the invention, the presser plate is not strictly flat but comprises an excessive thickness in the central part, constituting a type of stamp which increases the compression force locally and in particular perpendicular to the rolls at the centre of each module. This allows good alignment of the rolls of one same module which, during the positioning of the band, has a certain tendency to arrange itself in an arc, the centre roll acting as the key stone.

Further advantageous details and characteristics of the invention are described hereinbelow with reference to Figure 1 attached which shows a perspective view of a compression station of a device according to the invention.

As has already been indicated, the invention applies to rolls and, more particularly, . to felt rolls based on glass wool. These rolls C' are, for example, obtained by operating according to the procedures described in the patent applications FR-A-2 553 744, EP-A-238 393 or EPA-294 320, or any other process which is suitable for producing a roll with a compression which is as uniform as possible over the entire length of the strip of felt which is rolled up in such a manner as to lead to the formation of coils, all of the same thickness, including the first turns which form the heart of the roll and, likewise, the most fragile part thereof.

If adequate precautions are taken at the point at which the felt strip is rolled about itself, a felt based on glass wool may support compression rates of four or more, which signifies that the thickness of the rolled-up strip is less than a quarter of the initial thickness, the initial thickness being recovered when the band is unrolled. Generally, all the rolls are produced with identical diameters, irrespective of the thickness of the strip, in such a manner as to · keep substantially constant dimension and weight, which simplifies the conditioning thereof. Below, and to provide a point of reference of the concept, reference will therefore be made to a roll of the type of 400 mm to 410 mm in diameter and 1200 mm length, but it is obvious that the process according to the invention may be applied to rolls of different diameters. Likewise, the number of rolls per module or per batch and half batch may of course be modified and adapted to each particular case within the framework of the invention.

In a first stage, the rolls, each of which is covered in a heat-shrunk polyethylene film, or, more simply, in kraft paper, are joined in modules of five, each module being banded. In one module, the rolls are layered side by side, disposed in the same alignment. This banding is under tension and thus deforms the rolls which become oval rather than cylindrical with their largest dimension being along the vertical. Typically, the module has a height of the order of 445 mm and a length of 1495-1500 mm, which represents a slight crushing on the sides.

In a second stage, the modules are superimposed, as is shown in Figure 1, where there is shown, schematically, a stack formed of three modules 1, of five rolls retained by a band 2 which has been shrunk. As a result of the fact that this band slightly compresses the rolls, the upper generatrices of the rolls of a given module - or, respectively, the lower generatrices - are, in fact, not strictly coplanar but define an arced curve, one roll - most often the central roll - acting as a key stone. This phenomenon may be restrictive insofar as the more the batches produced are parallelepipedal, the less the bulkiness thereof will be. A suitable shape of the presser plate according to the invention allows this problem to be corrected in a perfect manner as will be shown below.

The stack of three modules which is formed in this manner thus has a height of between 1330 and 1340 mm. It is transported for example by a conveyor belt 3 to the compression station. This compression station is protected by lateral grids 4, the role of which is simply to ensure the safety of the personnel of the conditioning line which will be brought into operation on the conveyor belt. The essential member is a presser plate 5, formed in this case as a block of reinforced concrete weighing three tonnes, supported by a metallic framework with commercial shapes .

The presser plate 5 is displaced by means of a block and tackle 6 which is able to displace the plate at a slow or fast speed (for example at a speed of the order of 1 m/min at the moment of compression and of 4 m/min during the cycles of lowering and raising the plate). The block and tackle 6 is supported by a metallic framework 7 which, furthermore, acts to guide the presser plate provided with a sliding guiding system on the stations of the framework, and which, furthermore, supports the conveyor belt 3 to compensate the deformation thereof due to the compression forces .

The assembly likewise comprises a safety device which operates by locking the presser plate 5 in the raised position, this device being, for example, formed by bars 8 on which there come to abut claws 9 associated with the presser plate 5, thus preventing the descent thereof. When the system is in operation, these bars 8 are retracted by a link 10 which is controlled manually in the case shown here, but which may also be controlled in automatic operation by means for detecting the presence of a batch.

The presser plate 5 comprises, in its central part, opposite the rolls at the centre of the pile, an excess thickness forming a type of stamp, which allows various modules to be reduced to flatness.

The stack of three modules being positioned in the compression station, the presser plate 5 is lowered and crushes the stack in such a manner as to reduce the height thereof to a value of, for example, between 950 and 1000 mm. A vertical compression of this type is partially compensated by an increase in the length of the modules which, depending on the case, reaches 30 to 50 mm. A compression of this type of these rolls, which is added to the compression of the felt performed during the rolling up is, in itself, completely inadmissible and unavoidably leads to significant damage to the felt, with a loss of recovery of thickness, if it is kept up for a relatively long period of time.

Nevertheless, it has become apparent that damage of this type is not produced if this period of time is sufficiently short. In practice, and always in the above-mentioned case, this compression is kept up for a duration which is not less than 15 seconds nor greater than 40 seconds and, preferably, is between 20 and 30 seconds. If it is selected to compress the charge further, for example by means of a heavier presser plate, this compression duration is preferably slightly reduced. In the opposite case, it could be lengthened, although this solution is not generally preferred because it leads to a slowing of production speeds.

This compression phase having been accomplished - and it not being desired to retain the batch in a state of compression of this type by any means of the type of hooping or surrounding with a wrapping strip, etc - the presser plate 5 is again raised to the high position and the stack of three modules is thus released. At that moment, as a result of elasticity of the material, there is a loosening of the stack which stabilises at a height of between 1200 and 1230 mm, ie. an increase of more than 100 mm in relation to the initial height. Examination of the rolls, shows, furthermore, that they do not totally recover their initial cylindrical shape, but tend towards a more parallelepipedal form with a more squared cross-section, the increase in height being substantially due to the reduction of the unoccupied free space between the rolls. Furthermore, the oval-shaped deformation of the rolls has practically disappeared, and stacking is more compact.

The stack is thus removed and rotated by 90° by a suitable tilting device, in such a manner as to dispose the rolls in an upright position. A further identical step is thus formed and, by means of a clamping device, for example of the pincer type, the two stacks are positioned on one other on a pallet, care being taken to ensure that the rolls of the upper line are well aligned with the lower rolls. The batch thus formed is retained definitively in its state by using a wrapping strip using a plastics material film which can be stretched. This wrapping with a strip allows loosening of the batches which may possibly be a little bit too great to be compensated, without, on the other hand, compressing the batches more (the rolls expand as a result of a loosening, not of swelling, or, in other words, the air removed between the rolls during the compression does not reenter the stack during the stop phase).

Without modifying the final rate of compression of the product, the invention allows the coefficient of filling the means of transport (railroad wagons or lorries) to be substantially improved, the batches being of a reduced bulkiness.

It should be noted that the invention is not restricted to the embodiment proposed and that various embodiments may be selected: thus, it is possible for the modules not to be glued but to be retained by some kind of binding. The stack may likewise be held before compression by wrapping with a strip, which thus renders the bands of the modules useless. Finally, the mobile presser plate may be replaced by a fixed plate associated with a hydraulic table.

Claims (10)

1. Method of producing a batch of rolls of compressible materials, comprising the following stages: . forming modules, each of which is formed of a layer of rolls, placed side by side, in contact with one another; . superimposing several modules in a stack, the rolls being disposed in a layered manner, said process being characterised by the following additional stages : . compressing this assembly of superimposed modules in the direction in which the modules are stacked, the compression bringing the thickness of the assembly to a height which corresponds to a rate of compression of the felt, which constitutes the compressible material, which is greater than the rate of compression corresponding to the elastic limit thereof; . cessation of compression in order to allow this assembly to expand; . positioning of ties to control the stack of modules at the dimensions obtained.

2. Method according to Claim 1, characterised in that, prior to the positioning of the ties, said assembly is turned in such a manner as to dispose the rolls in an upright position.

3. Method according to Claim 1 or Claim 2, characterised in that the compression is maintained for a duration which is neither less than 15 seconds nor greater than 40 seconds.

4. Method according to any one of Claims 1 to 3, characterised in that two stacks of rolls are superimposed before the ties are placed in position.

5. Method according to any one of Claims 1 to 4, characterised in that the modules are banded.

6. Method according to any one of Claims 1 to 5, characterised in that the stack of modules is rendered rigid by gluing, the bands being heated.

7. Method according to any one of Claims 1 to 4, characterised in that the stack of modules is rendered rigid by a binding.

8. Method according to any one of Claims 1 5 to 4, characterised in that the stack of modules is provided with a wrapping strip.

9. Method according to one of Claims 1 to 8, characterised in that the force which is exerted is greatest at the centre.

10. 10. A method of producing a batch of rolls of compressible materials, according to claim 1, substantially as herein described with reference to the accompanying drawing.