CA1061974A - Manufacture of plastics material articles - Google Patents
Manufacture of plastics material articlesInfo
- Publication number
- CA1061974A CA1061974A CA236,879A CA236879A CA1061974A CA 1061974 A CA1061974 A CA 1061974A CA 236879 A CA236879 A CA 236879A CA 1061974 A CA1061974 A CA 1061974A
- Authority
- CA
- Canada
- Prior art keywords
- web
- chain
- thermoforming
- plastics material
- links
- 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.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
- B29C51/26—Component parts, details or accessories; Auxiliary operations
- B29C51/261—Handling means, e.g. transfer means, feeding means
Abstract
A B S T R A C T
In the continuous heating of plastics sheet material the expansion of the undesirable material tends to result inwrinkling which causes undesirable temperature variations.
To compensate for the expansion without wrinkling the material 16 is supported on spikes 14A integral with links 12 of an endless chain 5 which are caused to progressively spread further apart as the material is carried through the heating zone. The spreading is effected by gradually straightening out kinks, which are initially introduced into the chain to bring the supporting links closer together at the entry E to the heating zone.
The technique is particularly applicable in the heat softening of plastics sheet material prior to thermoforming of articles such as drinking cups.
In the continuous heating of plastics sheet material the expansion of the undesirable material tends to result inwrinkling which causes undesirable temperature variations.
To compensate for the expansion without wrinkling the material 16 is supported on spikes 14A integral with links 12 of an endless chain 5 which are caused to progressively spread further apart as the material is carried through the heating zone. The spreading is effected by gradually straightening out kinks, which are initially introduced into the chain to bring the supporting links closer together at the entry E to the heating zone.
The technique is particularly applicable in the heat softening of plastics sheet material prior to thermoforming of articles such as drinking cups.
Description
1C~6~9~4 1 This invention rela-tes to the manufacture of thin walled plastics material articles which are formed from sheet plastics materials (whi.ch may be laminates).
Any suitable technique such as vacuum forminy, pressure forming, plug assist or mechanical forming or any combination of su~-h techniques may be used in the forming of the articles, but in all cases the sheet material is heated to effect a degree of softening of the material so that it can be for~ed, and therefore the forming of the articles will be referred to hereinafter and in thc appended claims simply and generally as "thermoforming".
Thermoforming i~ of course well known and is w.idely practised, and there are many thermoformed articles in every day US8 in many countries of the world, such articles including : domestic holloware and drinking cups.
Certain m~terials, and in particular polypropylene, polyethylene and expandedplastics sheets require to be thermo-formed at very accurate temperatures in order to achieve high speed production and high quality products.
In the heating of plastics sheet, it is known that many 20 types of plastics sheets wrinkle or sag when being heated, due ~ to lengthwise expansion of the sheet, and this can cause : temperature variations in the heated sheet, especially when the heating is carried out by a radiation heater.
~ The present lnvention seeks to provide a method of and apparatus or heating which is useful for webs of plastic.~
_ _ 9~
1ma-terial (which may be lamina-tes) includi]ng polystyrene A.B.S.
acrylonitrile nylon, polyester chloride, cellulose acetate and the so called "filled" plastics sheet produced from a mixture of plastics and particulate ma-terial such as talcum powder or the ~ike, and indeed any plastics material web which is capable of being thermoformed and which undergoes lengthwi~e expansion when heated. Such web will be referred to hereinafter and in the appended claims as "plastics web of the type aforesaid".
10According to ~he present invention there is provided a ; method for the manufacture of thin walled plastics material articles from plastics web of the type aforeshid wherei~ the articles are thermoformed in the web after heating thereof, and the web is heated whilst it is carried on spaced bracket6 on chain means, and the spacing betwean the brackets i~ extended to coMpensate for lengthwise expansion of the web. The heating may be effected by infra-red heaters as are used in co~ventional : thermoforming, but it is preferred that the heating should be by a fluid of gas and or vapour in a chamber in which the chains are located or through which the chains pass.
~ eating by such a fluid has the advantage o ansuring even he~ting of the she0t across its width, and the sheet can at no point reach a te~perature which is greater than that of the fluid.
The web will preferably be arranged to run through the chamber and directly to a thermoforming machine or unit at which 9~7~
1 the articles are Eormed. The shape and design of the articles are not important -to this inven-tion.
The invention also provides articles produced in accordance with the method as aforesaid.
The chains preferably carry the web at the longitudinal edges thereof and may trav01 in divergent paths to compensate for lateral extension of the web. To comp~nsa-te for lengthwise extensiOD, the chains may comprise links which are relatively movable in the direction of travel. These links may be progres~ively accelerated or may travel on a path o~ decreasing radius, either of which, will give the said lengthwi~e compensation.
In another arrangement, the chains may initially be given a kink or tuck to bring closer toge-ther portions o the chain which carry the web, and these portisns can be progres~ively spread as the chains move in their paths as the pla5tic5 sheeting carried thereby extends as being heated.
The latter arrangement provides a novel form of apparatus which can be used in the heating of plastic~ sheeting and in other applications and in accordance with another aspect of the invention there is provided a chain feed m~ahanism usable for carrying a web of plastics material of the type aforesaid or other material so that it can be heated whilst carri~d by the mechanism, comprising an endless chain ~ade up of pivotally inter-connected links, means whereby -the chain is caused to ~; 97~
1 travel in an endles~ path, spaced support brackets carried by the links of the chain and by which the web may be carried by the chaln, tuck means by which -the links of the chain between adjacent support bracke-ts can be relatively pivoted to bring such bracke.ts closer together, and guide mean~ for progressively spreading the adjacen-t bracke-ts which have been moved closer -together by said -tuck meansO a~ the chain moves along a portion of said endle~s path.
Preferably, the mechanism comprises two such chains which are arranged s~mmetrically and are adapted to operate in an identical and synchronous manner.
Preferably, the portions of chains w*lere said ~preading takes place are mutually divergent in the direction of travel of the chains.
Also, accordiny to the invention there is provided a thermoforming plant for producing thermoformed, thin walled plastics ma-terial articles comprising a chain feed apparatus as a~oresaid, and a thermoforming machine, the chain feed apparatus being located so as to feed a web of plastics material carried thereby directly to the -thermoforming machine.
An embodiment of the present invention will now be described by way of example, wi-th reference -to the accompanying drawings, wherein:-Figure 1 is ~ diayra~m~tic side viaw of a thermo~orming plant embodying the principles of the present invention;
1 Figure 2 is a diacJrammatic side elevation of part of an endless chain for carrying a plastics web of the typa a~oresaid;
Figure 3 is an enlarged side view of par-t of the chain sec-tlon shown in Figure 2 ; and Figure 4 is a still further enlarged view of part of the chain section shown in Figure 2, this view being slightly distorted in order to illus-trate the principle of operation of the invention.
Referriny firstly to Figure 1, a conventional thermoforming machine is represented by numeral 1, in which articles 2 are formed from a heated web 16 of thermoformable plastics material.
The heating of -the web 16 takes place in a heating chamber 3 immediately preceding the m~chine 1. The web 16 is rarried through the heating chamber 1 by endless chains 5, and receives the web from a roll 4 of plastics material stack. The remainder of the web 16, after forma-tion and removal of articles 2 is wound as at 6 on a take up roll.
Referring now to the other figure~s, and firstly to Figure 2, in this Eigure is shown a portion of one of the endless chains 5 which travels on the path marked A in the figure. In the apparatus there are two such endless chains symmetrically arranged about a cen-tral, vertical plane lying parallel -to the plane of the paper on which Figure 1 appears. Therefore, one comple-te chain is omit-ted from -the drawings, but its construction and operation are identical with the axrangement now to be described.
It will be noticed -that from t}-e xight hand portion of ~6~L979L
1 Figure 2, that the chain travels in a semi-circular path as it passes round an appropria-te guide sprocket as shown in Figure 1, it then travels i.n a generally horizontal direction as indicated by arrow B in Figure 2. The chain is made up of pivotably connected links lO and 12 best seen ln Flgure 4, the links lO
alternating with the links 12 and being pivotably interconnec-ted by connecting links 11 again bes-t shown in Figure 4. The links 12 are provided with brackets 14, having outwardly projectin~ spikes 14A for carrying the web 16 of synthetic plasticsmaterial to be heated. ~rhis web of plastics material best shown at 16 in Figures 1 and 2 and i5 drawn from the : spool 4 shown in Figures 1 and 2 appropriately posi.tioned in -:~ relatlon to the horizontaLly travelling portion~ of the chains 5. The brackets 14 have ledges 17 which run on the top horizontal surface of a track guide 18 lying in the direction of the horizontal path of movemen-t~indicated by arrow B in . Figure 2] of the web 16.
The utilisation of this chain S is to collect an edge of .; the web 16 (the other chain serving simultaneously to collect the other edge of the web) whilst adjacent brackets 14 are spaced closer together than they are by the time these brackets reach the end of the horizontal path B, so that longitudinal extension of the web due to heating -thereof can be compensated for by ; progressive d.isplacemen-t of adjacent brackets 14 and the web 1~1974 1 can be prevented from sagging. This is achieved by providing cam track to the underside of the rail 18 which in efect orms a "kink" or "tuck" in the chain by downwardly displacing onl~
the links lO as they pass station E of the guide rail, and by progressively allowing the lengths lO to move upwards as they travel along the horizontal path B. To this end, the underside of guide rail 18 has a downwardly inclined cam portion l~A and a gradually upward inclined guide portion 18B, located at opposite sides of station ~ as shown in Figure 2.
The motion o~ the links lO and 12 will be clearly understood from the drawings, and Figure 4 shows in enlarged form how the links 11 pivot as they pass station E, causing adjacent brackets 14 to move closer together. The web 16 is th~n applied to the spikes 14A and as the chain i~ pulled or driven in the direction of arrow B, the displaced links lO are locked against the underside of cam surface 18B, and as they move along this cam surface in the direction o arrow B, they progressively move back into alignment with links 12, and the angular displacement of links l3 gradually reduces to zero.
This has the effect of progressively increasiny the spacing between brackets 14 and thereby increasing the pitching between adjacenk spi~eS 14~as the chain moves in the direction of arrow B.
The extent of t~e initial tuck as dictated by the cam surface 18~ will depend upon the thermal extension of the web consistant with the length of travel of the chains, which takes '7~L
1 place in the direction of arrow B, to ensure full and adequate heating of the plastics material shee-t without sag.
The symmetrically arranged chains will pass through a suitable heating chamber in which -the web is heated, for example by a ~luid in the form of gas and~or vapour. Alternatively or additionally, the heating may be by infra-red heaters. From the heating chamber, the ho-t web can be passed directly to a thermoforming machin , or can be heated further by additional means before being passed to the ~hermoforming machine. In any event, the final articles are produced in the web in the thermoforming machine.
In Figure 4, the links l~ are shown as being moved from a position of maximum angular displacement to zero angular displacement relative to the links lO and 12 over a relatively short distance. This is for the purposes of explanation and in practire, the distance over which the links change in angularity rom maximum to zero, would be much greater.
It will be appreciated that the apparatu~ provides a simple and effective method of compensating for lengthwise extension of the heated web. If desired, the two chains making up the apparatus could be mutually divergent in the direction of arrow B in order to compensate for lateral expansion of the web. This apparatus can be used in other instances where it is desired to have an increase in pitching between chain carried ~6~9~4 1 members, and even where there is no heating o plastic~ material web involved at all, and instead of using two chains, it may be po ible to use only a single chain with appropriate brackets.
The driving sprocket for each chain is at the left hand end of the apparatus as shown in Figure 1, and a ten~n sprocket is applied to the other end of the chain 50 as to maintain the ledges 17 held firmly against the top surface of guide 18, and the links firmly against the cam surfaces of the gulde 18.
In actual fact, the links 10 are provided with extension rods forming cam followers extending outwardly from the chain and the~e rGds have rollers which engage cam surfaces laA and 18B. The ledges lt may engage a horizontal surface which i9 not integral with or part of the gulde 18, but the guide 18 has been shown in the example given as defining the surface engaged by ledges 17 and also the surfaces engaged by links 10 for simplicity of description.
Any suitable technique such as vacuum forminy, pressure forming, plug assist or mechanical forming or any combination of su~-h techniques may be used in the forming of the articles, but in all cases the sheet material is heated to effect a degree of softening of the material so that it can be for~ed, and therefore the forming of the articles will be referred to hereinafter and in thc appended claims simply and generally as "thermoforming".
Thermoforming i~ of course well known and is w.idely practised, and there are many thermoformed articles in every day US8 in many countries of the world, such articles including : domestic holloware and drinking cups.
Certain m~terials, and in particular polypropylene, polyethylene and expandedplastics sheets require to be thermo-formed at very accurate temperatures in order to achieve high speed production and high quality products.
In the heating of plastics sheet, it is known that many 20 types of plastics sheets wrinkle or sag when being heated, due ~ to lengthwise expansion of the sheet, and this can cause : temperature variations in the heated sheet, especially when the heating is carried out by a radiation heater.
~ The present lnvention seeks to provide a method of and apparatus or heating which is useful for webs of plastic.~
_ _ 9~
1ma-terial (which may be lamina-tes) includi]ng polystyrene A.B.S.
acrylonitrile nylon, polyester chloride, cellulose acetate and the so called "filled" plastics sheet produced from a mixture of plastics and particulate ma-terial such as talcum powder or the ~ike, and indeed any plastics material web which is capable of being thermoformed and which undergoes lengthwi~e expansion when heated. Such web will be referred to hereinafter and in the appended claims as "plastics web of the type aforesaid".
10According to ~he present invention there is provided a ; method for the manufacture of thin walled plastics material articles from plastics web of the type aforeshid wherei~ the articles are thermoformed in the web after heating thereof, and the web is heated whilst it is carried on spaced bracket6 on chain means, and the spacing betwean the brackets i~ extended to coMpensate for lengthwise expansion of the web. The heating may be effected by infra-red heaters as are used in co~ventional : thermoforming, but it is preferred that the heating should be by a fluid of gas and or vapour in a chamber in which the chains are located or through which the chains pass.
~ eating by such a fluid has the advantage o ansuring even he~ting of the she0t across its width, and the sheet can at no point reach a te~perature which is greater than that of the fluid.
The web will preferably be arranged to run through the chamber and directly to a thermoforming machine or unit at which 9~7~
1 the articles are Eormed. The shape and design of the articles are not important -to this inven-tion.
The invention also provides articles produced in accordance with the method as aforesaid.
The chains preferably carry the web at the longitudinal edges thereof and may trav01 in divergent paths to compensate for lateral extension of the web. To comp~nsa-te for lengthwise extensiOD, the chains may comprise links which are relatively movable in the direction of travel. These links may be progres~ively accelerated or may travel on a path o~ decreasing radius, either of which, will give the said lengthwi~e compensation.
In another arrangement, the chains may initially be given a kink or tuck to bring closer toge-ther portions o the chain which carry the web, and these portisns can be progres~ively spread as the chains move in their paths as the pla5tic5 sheeting carried thereby extends as being heated.
The latter arrangement provides a novel form of apparatus which can be used in the heating of plastic~ sheeting and in other applications and in accordance with another aspect of the invention there is provided a chain feed m~ahanism usable for carrying a web of plastics material of the type aforesaid or other material so that it can be heated whilst carri~d by the mechanism, comprising an endless chain ~ade up of pivotally inter-connected links, means whereby -the chain is caused to ~; 97~
1 travel in an endles~ path, spaced support brackets carried by the links of the chain and by which the web may be carried by the chaln, tuck means by which -the links of the chain between adjacent support bracke-ts can be relatively pivoted to bring such bracke.ts closer together, and guide mean~ for progressively spreading the adjacen-t bracke-ts which have been moved closer -together by said -tuck meansO a~ the chain moves along a portion of said endle~s path.
Preferably, the mechanism comprises two such chains which are arranged s~mmetrically and are adapted to operate in an identical and synchronous manner.
Preferably, the portions of chains w*lere said ~preading takes place are mutually divergent in the direction of travel of the chains.
Also, accordiny to the invention there is provided a thermoforming plant for producing thermoformed, thin walled plastics ma-terial articles comprising a chain feed apparatus as a~oresaid, and a thermoforming machine, the chain feed apparatus being located so as to feed a web of plastics material carried thereby directly to the -thermoforming machine.
An embodiment of the present invention will now be described by way of example, wi-th reference -to the accompanying drawings, wherein:-Figure 1 is ~ diayra~m~tic side viaw of a thermo~orming plant embodying the principles of the present invention;
1 Figure 2 is a diacJrammatic side elevation of part of an endless chain for carrying a plastics web of the typa a~oresaid;
Figure 3 is an enlarged side view of par-t of the chain sec-tlon shown in Figure 2 ; and Figure 4 is a still further enlarged view of part of the chain section shown in Figure 2, this view being slightly distorted in order to illus-trate the principle of operation of the invention.
Referriny firstly to Figure 1, a conventional thermoforming machine is represented by numeral 1, in which articles 2 are formed from a heated web 16 of thermoformable plastics material.
The heating of -the web 16 takes place in a heating chamber 3 immediately preceding the m~chine 1. The web 16 is rarried through the heating chamber 1 by endless chains 5, and receives the web from a roll 4 of plastics material stack. The remainder of the web 16, after forma-tion and removal of articles 2 is wound as at 6 on a take up roll.
Referring now to the other figure~s, and firstly to Figure 2, in this Eigure is shown a portion of one of the endless chains 5 which travels on the path marked A in the figure. In the apparatus there are two such endless chains symmetrically arranged about a cen-tral, vertical plane lying parallel -to the plane of the paper on which Figure 1 appears. Therefore, one comple-te chain is omit-ted from -the drawings, but its construction and operation are identical with the axrangement now to be described.
It will be noticed -that from t}-e xight hand portion of ~6~L979L
1 Figure 2, that the chain travels in a semi-circular path as it passes round an appropria-te guide sprocket as shown in Figure 1, it then travels i.n a generally horizontal direction as indicated by arrow B in Figure 2. The chain is made up of pivotably connected links lO and 12 best seen ln Flgure 4, the links lO
alternating with the links 12 and being pivotably interconnec-ted by connecting links 11 again bes-t shown in Figure 4. The links 12 are provided with brackets 14, having outwardly projectin~ spikes 14A for carrying the web 16 of synthetic plasticsmaterial to be heated. ~rhis web of plastics material best shown at 16 in Figures 1 and 2 and i5 drawn from the : spool 4 shown in Figures 1 and 2 appropriately posi.tioned in -:~ relatlon to the horizontaLly travelling portion~ of the chains 5. The brackets 14 have ledges 17 which run on the top horizontal surface of a track guide 18 lying in the direction of the horizontal path of movemen-t~indicated by arrow B in . Figure 2] of the web 16.
The utilisation of this chain S is to collect an edge of .; the web 16 (the other chain serving simultaneously to collect the other edge of the web) whilst adjacent brackets 14 are spaced closer together than they are by the time these brackets reach the end of the horizontal path B, so that longitudinal extension of the web due to heating -thereof can be compensated for by ; progressive d.isplacemen-t of adjacent brackets 14 and the web 1~1974 1 can be prevented from sagging. This is achieved by providing cam track to the underside of the rail 18 which in efect orms a "kink" or "tuck" in the chain by downwardly displacing onl~
the links lO as they pass station E of the guide rail, and by progressively allowing the lengths lO to move upwards as they travel along the horizontal path B. To this end, the underside of guide rail 18 has a downwardly inclined cam portion l~A and a gradually upward inclined guide portion 18B, located at opposite sides of station ~ as shown in Figure 2.
The motion o~ the links lO and 12 will be clearly understood from the drawings, and Figure 4 shows in enlarged form how the links 11 pivot as they pass station E, causing adjacent brackets 14 to move closer together. The web 16 is th~n applied to the spikes 14A and as the chain i~ pulled or driven in the direction of arrow B, the displaced links lO are locked against the underside of cam surface 18B, and as they move along this cam surface in the direction o arrow B, they progressively move back into alignment with links 12, and the angular displacement of links l3 gradually reduces to zero.
This has the effect of progressively increasiny the spacing between brackets 14 and thereby increasing the pitching between adjacenk spi~eS 14~as the chain moves in the direction of arrow B.
The extent of t~e initial tuck as dictated by the cam surface 18~ will depend upon the thermal extension of the web consistant with the length of travel of the chains, which takes '7~L
1 place in the direction of arrow B, to ensure full and adequate heating of the plastics material shee-t without sag.
The symmetrically arranged chains will pass through a suitable heating chamber in which -the web is heated, for example by a ~luid in the form of gas and~or vapour. Alternatively or additionally, the heating may be by infra-red heaters. From the heating chamber, the ho-t web can be passed directly to a thermoforming machin , or can be heated further by additional means before being passed to the ~hermoforming machine. In any event, the final articles are produced in the web in the thermoforming machine.
In Figure 4, the links l~ are shown as being moved from a position of maximum angular displacement to zero angular displacement relative to the links lO and 12 over a relatively short distance. This is for the purposes of explanation and in practire, the distance over which the links change in angularity rom maximum to zero, would be much greater.
It will be appreciated that the apparatu~ provides a simple and effective method of compensating for lengthwise extension of the heated web. If desired, the two chains making up the apparatus could be mutually divergent in the direction of arrow B in order to compensate for lateral expansion of the web. This apparatus can be used in other instances where it is desired to have an increase in pitching between chain carried ~6~9~4 1 members, and even where there is no heating o plastic~ material web involved at all, and instead of using two chains, it may be po ible to use only a single chain with appropriate brackets.
The driving sprocket for each chain is at the left hand end of the apparatus as shown in Figure 1, and a ten~n sprocket is applied to the other end of the chain 50 as to maintain the ledges 17 held firmly against the top surface of guide 18, and the links firmly against the cam surfaces of the gulde 18.
In actual fact, the links 10 are provided with extension rods forming cam followers extending outwardly from the chain and the~e rGds have rollers which engage cam surfaces laA and 18B. The ledges lt may engage a horizontal surface which i9 not integral with or part of the gulde 18, but the guide 18 has been shown in the example given as defining the surface engaged by ledges 17 and also the surfaces engaged by links 10 for simplicity of description.
Claims (9)
1. A chain feed mechanism usable for carrying a web of a thermoformable plastics material which undergoes lengthwise expansion when heated so that it can be heated whilst carried by the mechanism, comprising (a) an endless chain made up of pivotally inter-connected links, means whereby the chain is caused to travel in an endless path, (b) spaced support brackets carried by the links of the chain and by which the web may be carried by the chain, (c) tuck means by which the links of the chain between adjacent support brackets can be relatively pivoted to bring such brackets closer together, the tuck means comprising a cam track for deflecting selected ones of said tucks which have cam followers which engage said cam track at the start of said por-tion of said endless path, and (d) guide means for progressively spreading the adja-cent brackets which have been moved closer together by said tuck means, as the chain moves along a portion of said endless path, wherein said brackets have bearing plates which rest on a support strip extending along said portion of the endless path and prevent said brackets from being deflected whilst the said selected ones of said links are being deflected.
2. A chain feed mechanism according to claim 1, wherein the guide means is a guide track extending over part of said portion of the endless path and is engaged sequentially by the cam fol-lowers of said links.
3. A chain feed mechanism according to claims 1 or 2, wherein the brackets have spikes for penetrating the material to be held thereby.
4. A chain feed mechanism according to claims 1 or 2, wherein there are two of said chains which are identical and symmetrically arranged and are adapted to operate synchronously, the respective brackets being for holding the edges of a web of material.
5. A thermoforming plant for producing thermoformed, thin walled plastics material articles, comprising a chain feed appar-atus according to claim 1, and a thermoforming machine, the chain feed apparatus being located so as to feed a web of plastics material carried thereby directly to the thermoforming machine.
6. A thermoforming plant according to claim 5, wherein the chain feed apparatus passes through a heating chamber wherein the web of plastics material whilst held by the chain feed apparatus, can be heated to soften same.
7. In a method of manufacturing thin walled plastic material articles from polyolefin plastics web which is substantially free of orientation so that it will expand lengthwise and widthwise when heated to thermoforming temperature comprising holding the web along its edges on spaced holding means carried by chains which move in endless paths, carrying said web along portions of said endless paths, heating the web to thermoforming temperature whilst it moves along said portions of the endless paths, and thermoforming the heated sheet material to form articles therein the improvement that the said holding means of each chain are moved further apart lengthwise of said portions of each endless
7. In a method of manufacturing thin walled plastic material articles from polyolefin plastics web which is substantially free of orientation so that it will expand lengthwise and widthwise when heated to thermoforming temperature comprising holding the web along its edges on spaced holding means carried by chains which move in endless paths, carrying said web along portions of said endless paths, heating the web to thermoforming temperature whilst it moves along said portions of the endless paths, and thermoforming the heated sheet material to form articles therein the improvement that the said holding means of each chain are moved further apart lengthwise of said portions of each endless
Claim 7 continued....
path as they move along said portions of said endless paths to compensate for lengthwise expansion of the web and the holding means of the respective chains are moved apart as they move along said portions of the endless path to compensate for width-wise expansion of the web so that web is supported without sag-ging and without being stretched by the moving holding means.
path as they move along said portions of said endless paths to compensate for lengthwise expansion of the web and the holding means of the respective chains are moved apart as they move along said portions of the endless path to compensate for width-wise expansion of the web so that web is supported without sag-ging and without being stretched by the moving holding means.
8. A method according to claim 7 wherein the holding means comprise spikes which are moved upwardly so that the web becomes impaled thereon, and are moved downwardly to remove the web from the spikes.
9. In the known method of manufacturing thin-walled plastics material articles from an elongated polyolefin plastic web which is substantially free of orientation so that it will expand lengthwise and widthwise when heated to thermoforming temperature, which method comprises holding the plastics material web adjacent its opposed lateral edges, moving said web through a heating zone so as to soften the web to thermoforming tempera-ture, and thermoforming the thus heated web at a thermoforming zone to form thin walled plastics material articles therefrom, the improvement which comprises:
(a) moving the lateral edges of said plastics material web laterally with respect to each other and with respect to the longitudinal axis of said web after heating same and as said plastics material web moves towards said thermoforming zone;
(b) moving the plastics material web in a longitudinal direction at a faster rate near the outlet of said heating zone than at the inlet of said heating zone, whereby the normal inclination of the plastic web to sag because of the longitudinal and lateral expansion of the web due to heating in the heating zone is effectively eliminated by the simultaneous movements set forth in a) and b).
(a) moving the lateral edges of said plastics material web laterally with respect to each other and with respect to the longitudinal axis of said web after heating same and as said plastics material web moves towards said thermoforming zone;
(b) moving the plastics material web in a longitudinal direction at a faster rate near the outlet of said heating zone than at the inlet of said heating zone, whereby the normal inclination of the plastic web to sag because of the longitudinal and lateral expansion of the web due to heating in the heating zone is effectively eliminated by the simultaneous movements set forth in a) and b).
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB43080/74A GB1495961A (en) | 1974-10-04 | 1974-10-04 | Manufacture of plastics material articles |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1061974A true CA1061974A (en) | 1979-09-11 |
Family
ID=10427243
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA236,879A Expired CA1061974A (en) | 1974-10-04 | 1975-10-02 | Manufacture of plastics material articles |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS5163865A (en) |
| BE (1) | BE834137A (en) |
| BR (1) | BR7506500A (en) |
| CA (1) | CA1061974A (en) |
| CH (1) | CH593121A5 (en) |
| DE (1) | DE2544193A1 (en) |
| DK (1) | DK440975A (en) |
| ES (1) | ES441451A1 (en) |
| GB (1) | GB1495961A (en) |
| IT (1) | IT1043067B (en) |
| NL (1) | NL7511620A (en) |
| NO (1) | NO143868C (en) |
| SE (1) | SE407177B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3432740A1 (en) * | 1984-09-06 | 1986-03-13 | Adolf Illig Maschinenbau Gmbh & Co, 7100 Heilbronn | Process for transporting and heating a polyolefin film and device for carrying out the process |
| DE3716603C1 (en) * | 1987-05-18 | 1989-03-09 | Dornier Gmbh Lindauer | Device for simultaneous biaxial treatment of film webs |
| JPH04308703A (en) * | 1991-04-05 | 1992-10-30 | Matsugu Giken Kogyo Kk | Sheetlike thermoplastic resin material molding device |
| FR2966376B1 (en) * | 2010-10-21 | 2012-11-02 | Moreno Innocente Marchante | DEVICE FOR STRETCHING SYNTHETIC FILM IN THE TRANSVERSE DIRECTION AND PROVIDING LONGITUDINAL CONTROLLED RELAXATION THEREOF |
-
1974
- 1974-10-04 GB GB43080/74A patent/GB1495961A/en not_active Expired
-
1975
- 1975-09-30 DK DK440975A patent/DK440975A/en not_active Application Discontinuation
- 1975-10-02 ES ES441451A patent/ES441451A1/en not_active Expired
- 1975-10-02 NL NL7511620A patent/NL7511620A/en not_active Application Discontinuation
- 1975-10-02 NO NO753327A patent/NO143868C/en unknown
- 1975-10-02 BE BE160643A patent/BE834137A/en unknown
- 1975-10-02 IT IT27889/75A patent/IT1043067B/en active
- 1975-10-02 CA CA236,879A patent/CA1061974A/en not_active Expired
- 1975-10-03 SE SE7511106A patent/SE407177B/en unknown
- 1975-10-03 DE DE19752544193 patent/DE2544193A1/en not_active Withdrawn
- 1975-10-03 CH CH1291375A patent/CH593121A5/xx not_active IP Right Cessation
- 1975-10-04 JP JP50120230A patent/JPS5163865A/ja active Pending
- 1975-10-06 BR BR7506500*A patent/BR7506500A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| NO143868B (en) | 1981-01-19 |
| DE2544193A1 (en) | 1976-04-08 |
| GB1495961A (en) | 1977-12-21 |
| NO143868C (en) | 1981-04-29 |
| NL7511620A (en) | 1976-04-06 |
| BR7506500A (en) | 1976-08-10 |
| AU8535475A (en) | 1977-04-21 |
| CH593121A5 (en) | 1977-11-30 |
| IT1043067B (en) | 1980-02-20 |
| JPS5163865A (en) | 1976-06-02 |
| DK440975A (en) | 1976-04-05 |
| SE407177B (en) | 1979-03-19 |
| ES441451A1 (en) | 1977-07-01 |
| NO753327L (en) | 1976-04-06 |
| SE7511106L (en) | 1976-04-05 |
| BE834137A (en) | 1976-02-02 |
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