CA1047713A - Method and means for producing laminated sheets - Google Patents
Method and means for producing laminated sheetsInfo
- Publication number
- CA1047713A CA1047713A CA207,755A CA207755A CA1047713A CA 1047713 A CA1047713 A CA 1047713A CA 207755 A CA207755 A CA 207755A CA 1047713 A CA1047713 A CA 1047713A
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- CA
- Canada
- Prior art keywords
- plastified
- heat
- rod
- sheet
- layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A thermoplastic sheet comprising a lamina-bearing base is produced by feeding a heat-plastified laminated rod in-to a conventional sheet-forming die. The laminated rod is formed using an adaptor die which is interposed between a rod-forming die and the sheet-forming die and which deposits a layer of heat-plastified material constituting the lamina on a segment of the peripheral surface of the cross-section of a heat-plastified rod of the base material, as the rod is extruded from the rod-forming die. The sheet-forming die converts the heat-plastified laminated rod into a laminated sheet.
A thermoplastic sheet comprising a lamina-bearing base is produced by feeding a heat-plastified laminated rod in-to a conventional sheet-forming die. The laminated rod is formed using an adaptor die which is interposed between a rod-forming die and the sheet-forming die and which deposits a layer of heat-plastified material constituting the lamina on a segment of the peripheral surface of the cross-section of a heat-plastified rod of the base material, as the rod is extruded from the rod-forming die. The sheet-forming die converts the heat-plastified laminated rod into a laminated sheet.
Description
; BACKGROUND OF THE INVENTION
This invention relates to ar. improved method ar.d means for producing lamina-bearing thermoplastic sheets.
The lamina on sheets of the type described cosmetical-ly improve products thermally formed from such sheets as well as give rise to improved performance results. In many products that must resist impact loads, such as cups for vending machines, it is conventional to thermally form the products from sheets of butadiene-styrene, which is a thermoplastic material having high impact strength characteristics. Unfortunately, this ma-terial, when extruded in sheet form, has a dull, matte finish which makes the resultant cups iess attractive than would be the case were the finish glossy. Cups formed from sheets of crys-tal polystyrene have a high gloss finish; and, while they are much more attractive than cups formed from high-impact strength polystyrene, they are too brittle to be of practical use. One approach to the problem of providing the desired appearance and performance characteristics is to thermally form the cups from a sheet in which a lamina of axially oriented polystyrene, for example, is applied to a base of high impact strength polysty-rene. The lamina provides the desired glossy finish while the base layer provides the desired strength. Vending cups thermal-ly formed from laminated sheets are generally considerably more expensive than cups formed from plain sheets because of the ~ -cost~ involved in fabricating the laminated sheets. Such sheets are conventionally formed by actually laminating one sheet to another subsequent to the extrusion of each sheet, or by co-ex-trusion processes using complex dies and apparatus. Often, it is difficult to convince users that the improved apparance of a product achieved using laminated sheets justifies the added ... - , . . , :~
, . - .
cost.
In the cases of other thermally formed products where the cosmetic aspect is dominated by mandatory performance speci-fications, there may be no alternative to using laminated -sheets. Examples of such products are those requiring different colors on opposite sides, those requring a radiation-stable film on one or both surfaces, or those requiring a chemical resis-tant film on one or both surfaces. In each of these cases, the expense of laminating sheets with special properties to base sheets can be justified. Obvious advantages are to be derived, however, from reducing the costs of producing laminated sheets from which products are to be thermally formed; and it is the object of the present invention to provide a new and improved method and means by which the desired lamination is achieved during the sheet extrusion process.
S~MMARY OF THE INVENTION
Briefly, a thermoplastic sheet comprising a base and a lamina is produced in accordance with this invention by feed-ing a heat-plastified laminated rod into a conventional sheet-forming die. The laminated rod has a centre core of the basematerial, and a thin outer layer of material having the desired special properties. The outer layer extends less than half-way around the periphery of the cross-section of the core, if the lamina is to be on one side of the sheet only; or, if the lamina is to be on both sides of the base sheet, it is deposited in two discrete layers, each of which extends around the per-iphery of the cross-section of the core, in effect "sandwiching"
the core.
The laminated rod is formed using an adaptor extru- -~
sion-die interposed between a conventional rod-forming extru-
This invention relates to ar. improved method ar.d means for producing lamina-bearing thermoplastic sheets.
The lamina on sheets of the type described cosmetical-ly improve products thermally formed from such sheets as well as give rise to improved performance results. In many products that must resist impact loads, such as cups for vending machines, it is conventional to thermally form the products from sheets of butadiene-styrene, which is a thermoplastic material having high impact strength characteristics. Unfortunately, this ma-terial, when extruded in sheet form, has a dull, matte finish which makes the resultant cups iess attractive than would be the case were the finish glossy. Cups formed from sheets of crys-tal polystyrene have a high gloss finish; and, while they are much more attractive than cups formed from high-impact strength polystyrene, they are too brittle to be of practical use. One approach to the problem of providing the desired appearance and performance characteristics is to thermally form the cups from a sheet in which a lamina of axially oriented polystyrene, for example, is applied to a base of high impact strength polysty-rene. The lamina provides the desired glossy finish while the base layer provides the desired strength. Vending cups thermal-ly formed from laminated sheets are generally considerably more expensive than cups formed from plain sheets because of the ~ -cost~ involved in fabricating the laminated sheets. Such sheets are conventionally formed by actually laminating one sheet to another subsequent to the extrusion of each sheet, or by co-ex-trusion processes using complex dies and apparatus. Often, it is difficult to convince users that the improved apparance of a product achieved using laminated sheets justifies the added ... - , . . , :~
, . - .
cost.
In the cases of other thermally formed products where the cosmetic aspect is dominated by mandatory performance speci-fications, there may be no alternative to using laminated -sheets. Examples of such products are those requiring different colors on opposite sides, those requring a radiation-stable film on one or both surfaces, or those requiring a chemical resis-tant film on one or both surfaces. In each of these cases, the expense of laminating sheets with special properties to base sheets can be justified. Obvious advantages are to be derived, however, from reducing the costs of producing laminated sheets from which products are to be thermally formed; and it is the object of the present invention to provide a new and improved method and means by which the desired lamination is achieved during the sheet extrusion process.
S~MMARY OF THE INVENTION
Briefly, a thermoplastic sheet comprising a base and a lamina is produced in accordance with this invention by feed-ing a heat-plastified laminated rod into a conventional sheet-forming die. The laminated rod has a centre core of the basematerial, and a thin outer layer of material having the desired special properties. The outer layer extends less than half-way around the periphery of the cross-section of the core, if the lamina is to be on one side of the sheet only; or, if the lamina is to be on both sides of the base sheet, it is deposited in two discrete layers, each of which extends around the per-iphery of the cross-section of the core, in effect "sandwiching"
the core.
The laminated rod is formed using an adaptor extru- -~
sion-die interposed between a conventional rod-forming extru-
- 2 -, :
sion die and the sheet-forming extrusion die. The adaptor die t by reason of the location and size of its orifice, deposits a layer of heat-plastified lamina material on a portion only of the outer surface of a heat-plastified rod of the base materia7 as the rod is being extruded from the rod-forming die thus establishing the laminated rod. The sheet-forming die ex rudes the heat-plastified laminated rod into the desired laminated sheet. The peripheral zone of application of the lamina materi-al onto the core is restricted to permit greater uniformity 10. of coating across the finished sheet.
The more important features of thi~ invention have thus been outlined rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contribution to the art may be better appre-ciated. There are, of course, additional features of the in-vention that will be described hereinafter and which will also form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for de-signing other structures for carrying out the several purposes -of this invention. It is important, therefore, that the claims to be granted herein shall be of sufficient breadth to prevent ;~
the appropriation of this invention by those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS -_ ; For a more complete understanding of the nature and objects of the invention, reference should be had to the follow- ~-ing detailed description taken in connection with the accompany- ;~
ing drawings wherein: -Figure 1 is a schematic representation of an extru- -sion assembly made in accordance with the 104~13 present invention;
Figure 2 is a sectional view of the extruder-adaptor ~
assembly shown in Figure l; -Figure 3 is a sectional view taken along the lines
sion die and the sheet-forming extrusion die. The adaptor die t by reason of the location and size of its orifice, deposits a layer of heat-plastified lamina material on a portion only of the outer surface of a heat-plastified rod of the base materia7 as the rod is being extruded from the rod-forming die thus establishing the laminated rod. The sheet-forming die ex rudes the heat-plastified laminated rod into the desired laminated sheet. The peripheral zone of application of the lamina materi-al onto the core is restricted to permit greater uniformity 10. of coating across the finished sheet.
The more important features of thi~ invention have thus been outlined rather broadly in order that the detailed description thereof that follows may be better understood, and in order that the contribution to the art may be better appre-ciated. There are, of course, additional features of the in-vention that will be described hereinafter and which will also form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for de-signing other structures for carrying out the several purposes -of this invention. It is important, therefore, that the claims to be granted herein shall be of sufficient breadth to prevent ;~
the appropriation of this invention by those skilled in the art.
BRIEF DESCRIPTION OF THE DRAWINGS -_ ; For a more complete understanding of the nature and objects of the invention, reference should be had to the follow- ~-ing detailed description taken in connection with the accompany- ;~
ing drawings wherein: -Figure 1 is a schematic representation of an extru- -sion assembly made in accordance with the 104~13 present invention;
Figure 2 is a sectional view of the extruder-adaptor ~
assembly shown in Figure l; -Figure 3 is a sectional view taken along the lines
3-3 in Figure 2;
Figure 4 is a perspective view of one part of the extruder-adaptor assembly;
Figure 5 is a perspective view, partially in section, showing the laminated-rod being formed;
Figure 6 is a schematic modification of the assembly - shown in Figure 1 for producing a three-layer sheet;
Figure 7 is a further schematic modification for pro-ducing a five-layer sheet; and Figure 8 are cross-sectional views of modified lami- -nated rods.
DESCRIPTION OF THE PREFERRE~ EMBODIMENTS
Referring now to Figure 1, reference numeral 10 desig-nates, in schematic form, apparatus capable of carrying out the desired lamination during the sheet extrusion process. Appara- - -tus 10 comprises a pair of conventional extruders 11, 12, an extrusion adaptor 13, and a sheet extruder 14. Extruder 11, in-.
cludes the conventional means for producing a rod 15 (Figure 5) of heat plastified material at the discharge orifice of an extrusion die mounted at the output end of the extruder.
Extruder 12, in a similar fashion, produces heat-plastified material that is to become the lamina, and furnishes such material via conduit 18 to extrusion adaptor 13. The -adaptor 13, shown in detail in Figures 2, 3 and 4, permits a layer 19 (Figure 5) of the material produced by extruder 12 to - . . . - . . :
, . - . . ,.. . . , -. ~ : . . . : , .
10477~3 be deposited on the periphery of rod 15. As shown iri Figs.:- 5, layer 19 covers between 90 and 150 degrees of the periphery of the cross-section of rod 15 as the latter is extruded to estab-lish a heat-plastified laminated rod 20. In any event, the lamina 19 is deposited onto the rod 15 throughout an arc that is less than 180 degrees (in transverse cross-section), although best uniformity of coating of lamina 24 onto base layer 23 has been achieved if the angle of application ("a" in Figures 3 and 5) is between 90 and 150 degrees. With this arrangement, a 10. two-layer laminated sheet 21 is produced by passing the heat-plastified laminated rod 20 through sheet extrusion die 14.
Sheet 21 issuing from orifice 22 in die 14, comprises a base layer 23 of the material of rod 15, and a lamina 24 of the material of layer 19. In a conventional manner, not shown, sheet 21 is cooled and stored.
Referring now to Figures 2, 3 and 4, adaptor 13 is ~--made up of two elements: mandrel 25 and housing 26 held to-gether by suitable fasteners (not shown). Mandrel 25 comprises -~ ~
circular flange 27 having cylindrical boss 16 projecting from -the downstream face 28 of the flange. The upstream face 29 of flange 27 is provided with a smaller boss 30 which nests in the extrusion cavity of extruder 11. Boss 16, having outer cylin-drical surface 17, is provided with an axial bore 31 forming a ~ -flow surface for the heat-plastified material furnished by extruder 11 for producing rod 15. Mandrel 25 thus serves the same purpose as, and may replace the usual rod extrusion die on extruder 11 which would normally furnish heat-plastified material to the sheet-extrusion die 14. On the other hand, by suitably modifying face 29 of the mandrel, the usual die asso-ciated with extruder 11 may be retained. In such case, the ~047713 adaptor would be interposed between the usual die of extruder 11 and sheet-extrusion die 14.
Housing 26 is provided with a countersunk recess 32 that has a first portion 33 (Figure 3) defined by a cylindrical surface matching and engaging surface 17 of boss 16 of the mandrel. Recess 32 also has a second portion defined by inner cylindrical surface 34 spaced from outer cylindrical surface 17 of the boss 16 to establish an arcuate manifold 35.
(See Fig. 3). Surface 34 on housing 26 and the portion of surface 17 on boss 16 opposite surface 34 are flow surfaces -over which lamina material moves in a heat plastified condition.
Housing 26 is also provided in its upstream face with bore 36 co-axial with and closely matching bore 31 in the boss, fo- forming a flow surface for heat-plastified material. The downstream face of the housing is provided with hub 37 that mates with a recess (not shown) in the sheet-forming die 14 whereby bore 36 is connected to the inlet of die 14. -Orifice means 38 interconnects manifold 35 with bores 31 and 36, so that continuity exists between the flow surfaces defining manifold 35 and the flow surfaces defining the two bores. In the preferred form of the invention, the free end 39 of boss 16 of mandrel 25 is generally conical in shape, and countersunk recess 32 of housing 26 has a conically shaped bottom 40 that closely matches and mates with the free end of the boss.
Orifice means 38, in such case, is achieved in part by relief - -portion 41 formed in the free end 39 of boss 16 throughout the arc "a", and in part, by the portion of frusto-conical surface 40 opposite portion 41. Relief portion 41 can be achieved by a milling operation that removes a predetermined amount of metal from mandrel 25. Note that manifold 35 also extends through the 16~47713 arc "a" as seen in Figure 3 so that the entrance 42 from the manifold to the orifice means, and the exit 43 from the orifice means to the concentric bores, each extend through the same arc.
Entrance 42, however, has a cross-sectional flow area larger than the cross-sectional flow area of exit 43 thus achieving a "noz-zle" effect on pressurized heat-plastified material contained in manifold 35. In the preferred form of the invention, the cross-sectional area of exit 43 is from about 2-1/2% to about 10% of the cross-sectional area of bores 31, 36 and the spacing between - -1~ surface 40 and 41 is of the order of magnitude of 0.040 inches.
As shown in Figures 2 and 3, radial bore 44 in housing 26 connects manifold 35 to the exterior of the housing and pro-vides means for passing heat-plastified material from conduit 18 -~
into the manifold. In operation, extruder 11 causes heat-plastified material for the base layer 23 of the finished sheet to be forced into bore 31 (Figure 2) forming heat-plastified rod 15 as seen in Figure 5. At the same time, extruder 12 causes heat-plastified material for lamina 24 of the finished sheet to -~
be forced through conduit 18 into manifold 35 forming a partial -:-~
annular ring of material as seen in Figure 5. The pressure exerted on the heat-plastified material in manif~ld 35 forces such material through orifice means 38 where it is deposited in layer 19 on rod 15 at the interface between bores 31 and 36. As seen in Figure 5, layer 19 extends through the arc "a" about a portion of the periphery of the cross-section of the rod.
Because the materials being extruded through bores 31, 36 and through orifice means 38 are in a heat-plastified state, and because the flow of materials is in the laminar region, no inter- --mixing of the materials occurs except at their interface where a true bond is achieved. On passing through sheet die 14, the - - : . -.
laminated rod 20 is formed into the desire~d laminated sheet.
Where it is desired to provide a three-layer sheet as shown in Figure 6, a modified adaptor 13' can be used. The modified adaptor has a pair of manifolds rather than one as shown in Figures 2, 3 and 4, and a pair of orifice means. In this case, the periphery of rod 15 would have two layers 19' of material deposited thereon, opposite each other across the rod, each of which covers a different arc "a"' and "b' n respectively of the periphery of the cross-section of the rod 10 . as shown in Figure 6. It will be noted that the arcs "a'~ and "b'" may be equivalent or may differ onè from the other, as desired, but that, taken together will comprise less than 360 degrees of the periphery of the rod. Adaptor 13' thus permits both layers to be deposited simultaneously. As described pre-viously, the passage of the laminated rod through the sheeting ~
die 14' produces the desired three-layer sheet 21'. -It is also possible to sequentially deposit the layers on the rod. In such case, two adaptors like that shown in Figure 3 would be connected serially.
Multi-layered sheets can be produced by serially arranging the adaptors 13a and 13b as shown in Figure 7. Here, a laminated rod 20~ is formed with two pairs of laminae pro--ducing a five-layered sheet 21". Other combinations of adaptors to provide simultaneous or sequential deposition of layers can be utilized. --While the dies shown in the drawing produce a round ;~
rod of heat-plastified material, it is sometimes preferred to produce oval shaped rods that may or may not have flattened or substantially flattened sides, to facilitate the sheeting pro-cess. In such case, the major axis would lie in the direction 1C)47713 of the width of the sheet as shown in Figure 8, and, each layer of lamina 19" or 19' n will be disposed less than half-way around the core 15" or 15'~, respectively, and generally of a ; width ~c~ less than, or up to the width "d" of the flattened portions of the oval shaped rods, as illustrated in Figure 8.
::
~' --.
Figure 4 is a perspective view of one part of the extruder-adaptor assembly;
Figure 5 is a perspective view, partially in section, showing the laminated-rod being formed;
Figure 6 is a schematic modification of the assembly - shown in Figure 1 for producing a three-layer sheet;
Figure 7 is a further schematic modification for pro-ducing a five-layer sheet; and Figure 8 are cross-sectional views of modified lami- -nated rods.
DESCRIPTION OF THE PREFERRE~ EMBODIMENTS
Referring now to Figure 1, reference numeral 10 desig-nates, in schematic form, apparatus capable of carrying out the desired lamination during the sheet extrusion process. Appara- - -tus 10 comprises a pair of conventional extruders 11, 12, an extrusion adaptor 13, and a sheet extruder 14. Extruder 11, in-.
cludes the conventional means for producing a rod 15 (Figure 5) of heat plastified material at the discharge orifice of an extrusion die mounted at the output end of the extruder.
Extruder 12, in a similar fashion, produces heat-plastified material that is to become the lamina, and furnishes such material via conduit 18 to extrusion adaptor 13. The -adaptor 13, shown in detail in Figures 2, 3 and 4, permits a layer 19 (Figure 5) of the material produced by extruder 12 to - . . . - . . :
, . - . . ,.. . . , -. ~ : . . . : , .
10477~3 be deposited on the periphery of rod 15. As shown iri Figs.:- 5, layer 19 covers between 90 and 150 degrees of the periphery of the cross-section of rod 15 as the latter is extruded to estab-lish a heat-plastified laminated rod 20. In any event, the lamina 19 is deposited onto the rod 15 throughout an arc that is less than 180 degrees (in transverse cross-section), although best uniformity of coating of lamina 24 onto base layer 23 has been achieved if the angle of application ("a" in Figures 3 and 5) is between 90 and 150 degrees. With this arrangement, a 10. two-layer laminated sheet 21 is produced by passing the heat-plastified laminated rod 20 through sheet extrusion die 14.
Sheet 21 issuing from orifice 22 in die 14, comprises a base layer 23 of the material of rod 15, and a lamina 24 of the material of layer 19. In a conventional manner, not shown, sheet 21 is cooled and stored.
Referring now to Figures 2, 3 and 4, adaptor 13 is ~--made up of two elements: mandrel 25 and housing 26 held to-gether by suitable fasteners (not shown). Mandrel 25 comprises -~ ~
circular flange 27 having cylindrical boss 16 projecting from -the downstream face 28 of the flange. The upstream face 29 of flange 27 is provided with a smaller boss 30 which nests in the extrusion cavity of extruder 11. Boss 16, having outer cylin-drical surface 17, is provided with an axial bore 31 forming a ~ -flow surface for the heat-plastified material furnished by extruder 11 for producing rod 15. Mandrel 25 thus serves the same purpose as, and may replace the usual rod extrusion die on extruder 11 which would normally furnish heat-plastified material to the sheet-extrusion die 14. On the other hand, by suitably modifying face 29 of the mandrel, the usual die asso-ciated with extruder 11 may be retained. In such case, the ~047713 adaptor would be interposed between the usual die of extruder 11 and sheet-extrusion die 14.
Housing 26 is provided with a countersunk recess 32 that has a first portion 33 (Figure 3) defined by a cylindrical surface matching and engaging surface 17 of boss 16 of the mandrel. Recess 32 also has a second portion defined by inner cylindrical surface 34 spaced from outer cylindrical surface 17 of the boss 16 to establish an arcuate manifold 35.
(See Fig. 3). Surface 34 on housing 26 and the portion of surface 17 on boss 16 opposite surface 34 are flow surfaces -over which lamina material moves in a heat plastified condition.
Housing 26 is also provided in its upstream face with bore 36 co-axial with and closely matching bore 31 in the boss, fo- forming a flow surface for heat-plastified material. The downstream face of the housing is provided with hub 37 that mates with a recess (not shown) in the sheet-forming die 14 whereby bore 36 is connected to the inlet of die 14. -Orifice means 38 interconnects manifold 35 with bores 31 and 36, so that continuity exists between the flow surfaces defining manifold 35 and the flow surfaces defining the two bores. In the preferred form of the invention, the free end 39 of boss 16 of mandrel 25 is generally conical in shape, and countersunk recess 32 of housing 26 has a conically shaped bottom 40 that closely matches and mates with the free end of the boss.
Orifice means 38, in such case, is achieved in part by relief - -portion 41 formed in the free end 39 of boss 16 throughout the arc "a", and in part, by the portion of frusto-conical surface 40 opposite portion 41. Relief portion 41 can be achieved by a milling operation that removes a predetermined amount of metal from mandrel 25. Note that manifold 35 also extends through the 16~47713 arc "a" as seen in Figure 3 so that the entrance 42 from the manifold to the orifice means, and the exit 43 from the orifice means to the concentric bores, each extend through the same arc.
Entrance 42, however, has a cross-sectional flow area larger than the cross-sectional flow area of exit 43 thus achieving a "noz-zle" effect on pressurized heat-plastified material contained in manifold 35. In the preferred form of the invention, the cross-sectional area of exit 43 is from about 2-1/2% to about 10% of the cross-sectional area of bores 31, 36 and the spacing between - -1~ surface 40 and 41 is of the order of magnitude of 0.040 inches.
As shown in Figures 2 and 3, radial bore 44 in housing 26 connects manifold 35 to the exterior of the housing and pro-vides means for passing heat-plastified material from conduit 18 -~
into the manifold. In operation, extruder 11 causes heat-plastified material for the base layer 23 of the finished sheet to be forced into bore 31 (Figure 2) forming heat-plastified rod 15 as seen in Figure 5. At the same time, extruder 12 causes heat-plastified material for lamina 24 of the finished sheet to -~
be forced through conduit 18 into manifold 35 forming a partial -:-~
annular ring of material as seen in Figure 5. The pressure exerted on the heat-plastified material in manif~ld 35 forces such material through orifice means 38 where it is deposited in layer 19 on rod 15 at the interface between bores 31 and 36. As seen in Figure 5, layer 19 extends through the arc "a" about a portion of the periphery of the cross-section of the rod.
Because the materials being extruded through bores 31, 36 and through orifice means 38 are in a heat-plastified state, and because the flow of materials is in the laminar region, no inter- --mixing of the materials occurs except at their interface where a true bond is achieved. On passing through sheet die 14, the - - : . -.
laminated rod 20 is formed into the desire~d laminated sheet.
Where it is desired to provide a three-layer sheet as shown in Figure 6, a modified adaptor 13' can be used. The modified adaptor has a pair of manifolds rather than one as shown in Figures 2, 3 and 4, and a pair of orifice means. In this case, the periphery of rod 15 would have two layers 19' of material deposited thereon, opposite each other across the rod, each of which covers a different arc "a"' and "b' n respectively of the periphery of the cross-section of the rod 10 . as shown in Figure 6. It will be noted that the arcs "a'~ and "b'" may be equivalent or may differ onè from the other, as desired, but that, taken together will comprise less than 360 degrees of the periphery of the rod. Adaptor 13' thus permits both layers to be deposited simultaneously. As described pre-viously, the passage of the laminated rod through the sheeting ~
die 14' produces the desired three-layer sheet 21'. -It is also possible to sequentially deposit the layers on the rod. In such case, two adaptors like that shown in Figure 3 would be connected serially.
Multi-layered sheets can be produced by serially arranging the adaptors 13a and 13b as shown in Figure 7. Here, a laminated rod 20~ is formed with two pairs of laminae pro--ducing a five-layered sheet 21". Other combinations of adaptors to provide simultaneous or sequential deposition of layers can be utilized. --While the dies shown in the drawing produce a round ;~
rod of heat-plastified material, it is sometimes preferred to produce oval shaped rods that may or may not have flattened or substantially flattened sides, to facilitate the sheeting pro-cess. In such case, the major axis would lie in the direction 1C)47713 of the width of the sheet as shown in Figure 8, and, each layer of lamina 19" or 19' n will be disposed less than half-way around the core 15" or 15'~, respectively, and generally of a ; width ~c~ less than, or up to the width "d" of the flattened portions of the oval shaped rods, as illustrated in Figure 8.
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Claims (14)
1. In a method of extruding a plural layered sheet, the steps which comprise moving a heat plastified rod of a first material through a flow passage having a cross-section of predetermined shape, disposing a layer of a heat plastified second material over only less than 180° of the surface of said first material, whereby a plane may be extended through the edges of said second material and also longitudinally through said first material, and moving the heat plastified combined first and second materials through a co-extrusion die, distort-ing the shape of said combined materials together from their original shape and expanding it to that of a wide sheet, which is thinner than said cross-section, and which sheet extends substantially in said plane.
The method of claim 1, wherein the step of disposing the layer of second material occurs over an arc of between 90 and 150 degrees of the surface of said rod.
3. The method of claim 1, including the added steps of disposing a layer of heat-plastified third material on the first material prior to the step of passing them through said co-extrusion die.
4. The method of claim 3, wherein said added step occurs simultaneously with the step of disposing of said layer of said second material.
5. The method of claim 4, wherein said layer of third material is disposed over an opposite portion of the periphery of said first material from the layer of second material, to comprise an aggregate disposition over less than all of the periphery of the first material.
6. The method of claim 3, wherein said added step occurs subsequently to the step of disposing said layer of second material.
7. The method of claim 2, including the step of disposing a layer of third material over another arc of said first material, also within the arcuate range of 90 to 150 degrees.
8. The method of claim 1, wherein the initially extruded first material is of oval periphery having substantially flattened side portions, connected by arcuate portions, and wherein the layer is disposed on at least one substantially flattened side portion.
9. The method of claim 8, wherein similar layers are disposed on both substantially flattened side portions.
10. The method of claim 3, wherein said third material is also applied over less than 180° of the surface of said first material.
11. In an extrusion assembly for extruding a thermoplastic sheet from a rod of heat-plastified material which is produced by a first extruder and which is passed through a sheet extrusion die that converts the rod into a sheet, the improve-ment comprising means forming a separate source of heat-plastified material, means forming a conduit extending from said source and communicating with said rod, and applying means for depositing a layer of said heat-plastified material, said applying means being shaped to apply said heat-plastified material over less than half of the entire periphery of the cross-section of said rod as the latter is being extruded, whereby the sheet produced by said extrusion die is a laminate.
12. The invention of claim 11, wherein said applying means comprises:
(a) a mandrel with an axially extending boss having an outer cylindrical surface, said boss having an axial bore defining a flow surface for heat-plastified material produced by said first extruder for forming said rod;
(b) a housing having a recess with a first portion defined by a cylindrical surface that matches said cylindrical boss and into which the latter fits, and having an axial bore coaxial with and matching the bore in said boss and defining a flow surface for heat-plastified material, the axial bore in said housing being connected to said extrusion die for passing heat-plastified material to said extrusion die;
(c) said recess having a second portion defined by a sur-face spaced from the surface of said boss to establish a manifold;
(d) orifice means defined by said boss and said housing interconnecting said manifold with the flow surfaces;
(e) said orifice means opening into said flow surfaces along a path that is co-extensive with less than half the peri-phery of the cross-section of the bores in said boss and said housing; and (f) means for passing heat-plastified material to said manifold.
(a) a mandrel with an axially extending boss having an outer cylindrical surface, said boss having an axial bore defining a flow surface for heat-plastified material produced by said first extruder for forming said rod;
(b) a housing having a recess with a first portion defined by a cylindrical surface that matches said cylindrical boss and into which the latter fits, and having an axial bore coaxial with and matching the bore in said boss and defining a flow surface for heat-plastified material, the axial bore in said housing being connected to said extrusion die for passing heat-plastified material to said extrusion die;
(c) said recess having a second portion defined by a sur-face spaced from the surface of said boss to establish a manifold;
(d) orifice means defined by said boss and said housing interconnecting said manifold with the flow surfaces;
(e) said orifice means opening into said flow surfaces along a path that is co-extensive with less than half the peri-phery of the cross-section of the bores in said boss and said housing; and (f) means for passing heat-plastified material to said manifold.
13. The invention of claim 12, wherein the free end of said boss is generally conical in shape, and said orifice means is established in part by flow surfaces on the free end of said boss.
14. The invention of claim 12, wherein the axial bores in said boss and said housing are circular in cross-section.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA207,755A CA1047713A (en) | 1974-08-26 | 1974-08-26 | Method and means for producing laminated sheets |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA207,755A CA1047713A (en) | 1974-08-26 | 1974-08-26 | Method and means for producing laminated sheets |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1047713A true CA1047713A (en) | 1979-02-06 |
Family
ID=4100967
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA207,755A Expired CA1047713A (en) | 1974-08-26 | 1974-08-26 | Method and means for producing laminated sheets |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1047713A (en) |
-
1974
- 1974-08-26 CA CA207,755A patent/CA1047713A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |
Effective date: 19960206 |