GB2050925A - Improvements in or relating to the manufacture of containers - Google Patents
Improvements in or relating to the manufacture of containers Download PDFInfo
- Publication number
- GB2050925A GB2050925A GB8013222A GB8013222A GB2050925A GB 2050925 A GB2050925 A GB 2050925A GB 8013222 A GB8013222 A GB 8013222A GB 8013222 A GB8013222 A GB 8013222A GB 2050925 A GB2050925 A GB 2050925A
- Authority
- GB
- United Kingdom
- Prior art keywords
- container
- mould
- elastomeric
- shape
- final
- 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.)
- Granted
Links
- 238000004519 manufacturing process Methods 0.000 title description 3
- 239000000463 material Substances 0.000 claims abstract description 26
- 238000000034 method Methods 0.000 claims abstract description 18
- 239000004033 plastic Substances 0.000 claims abstract description 13
- 229920003023 plastic Polymers 0.000 claims abstract description 13
- 238000003856 thermoforming Methods 0.000 claims abstract description 6
- 239000013536 elastomeric material Substances 0.000 claims abstract description 5
- 238000000465 moulding Methods 0.000 claims description 6
- 230000015572 biosynthetic process Effects 0.000 claims description 5
- 229920002379 silicone rubber Polymers 0.000 claims description 5
- 229920001971 elastomer Polymers 0.000 description 4
- 229920001169 thermoplastic Polymers 0.000 description 2
- 239000004416 thermosoftening plastic Substances 0.000 description 2
- 239000004793 Polystyrene Substances 0.000 description 1
- 238000000071 blow moulding Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000035622 drinking Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229920005669 high impact polystyrene Polymers 0.000 description 1
- 239000004797 high-impact polystyrene Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 229920002223 polystyrene Polymers 0.000 description 1
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
- B29C51/08—Deep drawing or matched-mould forming, i.e. using mechanical means only
- B29C51/082—Deep drawing or matched-mould forming, i.e. using mechanical means only by shaping between complementary mould parts
- B29C51/085—Deep drawing or matched-mould forming, i.e. using mechanical means only by shaping between complementary mould parts with at least one of the shaping surfaces being made of resilien material, e.g. rubber
-
- 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
- B29C33/00—Moulds or cores; Details thereof or accessories therefor
- B29C33/44—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles
- B29C33/48—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles with means for collapsing or disassembling
- B29C33/50—Moulds or cores; Details thereof or accessories therefor with means for, or specially constructed to facilitate, the removal of articles, e.g. of undercut articles with means for collapsing or disassembling elastic or flexible
-
- 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
- B29C51/30—Moulds
- B29C51/34—Moulds for undercut articles
-
- 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
- B29C51/30—Moulds
- B29C51/34—Moulds for undercut articles
- B29C51/343—Moulds for undercut articles having recessed undersurfaces
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
- B29L2031/00—Other particular articles
- B29L2031/712—Containers; Packaging elements or accessories, Packages
- B29L2031/7132—Bowls, Cups, Glasses
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Blow-Moulding Or Thermoforming Of Plastics Or The Like (AREA)
- Moulds For Moulding Plastics Or The Like (AREA)
- Casting Or Compression Moulding Of Plastics Or The Like (AREA)
Abstract
The invention provides a method of differential pressure thermo-forming of an article from a sheet of plastics material in a mould, in which a part of the final shape of the container is moulded by the resilient deformation or flow of a mould portion which is formed of an elastomeric material. In the illustrated embodiment, a sheet is formed into a female mould 10 and the base of the sheet is deformed to provide a false bottom 13 by movement of a punch assembly 11. The punch assembly includes an elastomeric ring 16 which is put under pressure between sleeve 14 and core 12 at the end of the punch assembly stroke to cause the ring to flow outwardly and compress the double walled portion of the finished container to its final shape. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to the manufacture of containers
This invention relates to the manufacture of containers formed in synthetic plastics material sheet.
It is known to form containers such as food stuffs packaging containers or disposable drinking cups from thermo-plastics synthetic plastics material sheet such as high impact polystyrene or foam polystyrene material by various combinations of vacuum or blow moulding of the sheet material which has been made plastic by heating, with optional use of male or female moulds, or a combination of both to determine the shape of the finished article.
The male or female moulds used in such techniques have invariably been formed of rigid material and this has placed limitations on the shapes of article which can be moulded having regard to the need to remove the finished articles from the moulds without damage, unless complicated moulds are provided with movable portions.
It is an object of the present invention to provide a method and apparatus for moulding containers in sheet plastics material which enables previously difficult shapes to be moulded into the article without the use of complex moulds with movable portions.
Accordingly the present invention provides a method of differential pressure thermo-forming of a plastics material article from sheet material, in which a part of the final shape of the container is moulded by the resilient deformation and flow of a mould portion made of an elastomeric material. Preferably that elastomeric material is silicon rubber.
Preferably the resilient deformation and flow of the elastomeric mould portion is caused by squeezing it between two relatively movable members either or both of which members may form part of a mould for forming the container.
The part of the final shape of the article which is so formed may be an internal or an external feature in the finished container.
In one embodiment of the invention an article is moulded to an intermediate shape in a mould whereafter said mould portion is so deformed and flows to form said part of the final shape and is then released to regain its original free state for the removal of the finished article from the mould.
In one arrangement of the above embodiment, the mould comprises a female mould shell arranged to form an open hollow container, and the mould shell is provided with an axially movable punch assembly arranged to form the bottom of the container, the punch being axially moved in the mould shell to form a recess in the bottom of the container after it has been initially formed in the mould shell by raising the base of the container and folding the side wall over about the bottom edge of the container forming a double thickness of material around the recess, the punch assembly including the elastomeric mould portion which is so deformed and caused to flow to form the final shape of the recess.
In a further aspect the present invention provides mould apparatus for carrying out the method of the invention including a mould portion formed of elastomeric material and means for resiliently deforming that mould portion to finally mould an associated part of an article to be moulded.
In order to promote a fuller understanding of the above, and other aspects of the present invention, an embodiment will now be described, by way of example only, with reference to the accompanying drawing which shows in schematic cross-section a mould for the differential pressure thermo-forming of a plastics material container.
The drawing shows a mould for forming a plastics material container in cross-section taken through the axis of that mould. The upper half of the drawing shows the mould in an initial condition during the moulding process whereas the bottom half of the drawing shows the mould in a second position at the completion of the formation of the container.
The mould comprises a female mould shell 10 and a movable male mould assembly 11 in the form of a punch which is axially movable in the shell 10. The punch assembly 11 comprises a rigid portion 12 provided with a face 13 which is arranged to form the bottom or base of an container when it is moulded in the shell 10. Rigid portion 12 is slidably mounted in a sleeve 14 which is attached to a mechanism such as a fluid pressure operated piston and cylinder device indicated generally at 15 whereby the assembly 11 can be moved axially in the shell 10. A silicon rubber ring 16 is interposed between the sleeve 14 and a frusto-conical face 17 on the portion 12 disposed behind the outer part of the face 13.The portion 12 is provided with a stop member 18 which extends through a respective slot in the sleeve 14 to engage on an end face 19 of the mould shell 10 at a chosen point in the travel of the assembly 11 into the shell 10 to prevent further movement of the rigid portion 12.
When the stop 18 is in abutment with the end face 19, further operation of the device 15 resulting in further inward movement of the sleeve 14 squeezes the ring 16 against the surface 17.
In use the device is initially set in the position shown in the upper half of the drawing with the assembly 11 in its retracted position. A container is moulded in the cavity formed within the shell 10 from a sheet of heated thermo-plastics material by conventional techniques of differential pressure thermo-forming to a shape as indicated in heavy outline at 20 in the upper part of the figure. This step in the formation of a container may be carried out with the use of a male plug in the shell mould 10 and the application of pressure to the inside of the forming container optionally with the application of vacuum to the outside of the forming container in the shell mould 10.
After the outline 20 has been formed, the plug if used is retracted, and the assembly 11 advanced while the plastics material is still sufficiently warm for plastics flow, to the position shown in the bottom of the drawing to form a recess in the bottom of the container with the side wall material of the container being folded back about what becomes the bottom edge of the container indicated at 21 in the bottom half of the drawing.When the assembly 11 reaches the position shown in the bottom half of the drawing and the stop 18 abuts on the end face 19, further inward movement of the sleeve 14, as mentioned above, squeezes the ring 16 against the face 17, and causes it to expand radially outwardly to complete the folding of the side wall material so that the double thickness of side wall material is in contact from the bottom edge 21 to the level of the base 22 of the container which is formed on the face 13.
When this step has been completed, the operation of the device 15 is reversed with the result that the sleeve 11 first retracts allowing the ring 16to resume its normal shape and then the assembly 11 is retracted together with the rigid portion 12 to leave the finished container having a cross-section as indicated in heavy outline at 23 in the bottom half of the figure in the mould shell 10 for subsequent removal in known mannerperse.
It will be noted that by this means a finished container can be formed which has a re-entrant recess in its base without the use of a complicated punch assembly 11 with movable rigid portions. The squeezing of the rubber ring 16 ensures the final formation of the side walls of the recess in the bottom of the container against the frusto-conical surface of the shell mould 10, and on release when the sleeve 14 is retracted the ring 16 regains its original shape so that it can be removed from the re-entrant recess without damaging the finished container.
In order to assist in the operation of the device as discussed above, the shell mould 10 is formed to be frusto-conical to the point at which the edge 21 lies in the finished container, and thereafter cylindrical so that the extra portion formed in the initial step illustrated in the top half of the drawing, which will be folded back into the container to form the recess, is made cylindrical.
Various materials may be used for the ring 16, but silicon rubber has been found preferable. It is to be noted that the use of the ring 16 brings with it an additional advantage in that the elastomeric materials invariably have a lower thermal conductivity and tend to cool the material of the container less during contact with it so that the second forming operation may be more easily completed.
It is to be noted that the face 13 is of slightly smaller diameter than the diameter of the finished container at the finished level of the base of the container so that expansion of the rubber ring 16 in the final stages of forming the container stretches the base material around its periphery. This produces a slight peripheral downward chamfer in the base of the container. The provision of a groove as indicated at 24 in the face 13 forms a part-annular rib in the base of the container in the initial stage as indicated in the top half of the drawing, which assists in providing additional material in the base of the container to take up the slight stretching discussed above.
While the above discussion has been directed to the use of the rubber ring 16 for forming an internal re-entrant recess, it will be appreciated that a similar arrangement to that discussed can be used with a rubber portion in the shell mould 10 which may be arranged to be squeezed in a similar mannerforthe formation of external features on the container. In which case the ring would be used to form the container against an internal plug.
In the embodiment described above, it will be seen that the double thickness wall formed in the container around the recess in the bottom, is closed so that the two thicknesses are in contact at least adjacent the base 22 and substantially over the whole height of the double thickness portion. Thus if the containers are to be "stackable", the bottom edge 21 of a container nesting in a further container cannot enter the space between the double thickness and become wedged therein.
Claims (19)
1. A method of differential pressurethermoforming of an article from a sheet of plastics material in a mould, in which a part of the final shape of the container is moulded by the resilient deformation or flow of a mould portion which is formed of an elastomeric material.
2. A method as claimed in Claim 1, in which said mould portion is formed of silicon rubber.
3. A method as claimed in Claim 1 or 2, in which the remainder of the final shape is formed first and said part of the fianl shape is moulded subsequently.
4. A method as claimed in Claim 1, 2 or 3, in which said part of the final shape of the container is formed by deformation of the elastomeric mould portion in a direction transverse to the longitudinal axis of the container.
5. A method as claimed in Claim 1,2,3 or 4, in which said resilient deformation is achieved by squeezing the elastomeric mould portion between two relatively movable rigid members either or both of which form part of the mould.
6. A method as claimed in any one of Claims 1 to 5, in which said part of the final shape of the article is a feature extending inwardly from the general shape of the container.
7. A method as claimed in Claim 6, in which said feature is re-entrant so as to be divergent in cross-section in the inward direction.
8. A method as claimed in any preceding Claim, in which said part of the final shape is moulded to an intermediate shape whereafter said elastomeric mould portion is so deformed to form said part to its final shape and then released to regain its original free shape for the removal of the finished article from the mould.
9. A method as claimed in any preceding Claim, comprising forming an intermediate open hollow container in a female mould shell having an axially movable punch assembly which includes said elastomeric mould portion, axially advancing the punch assembly in the mould shell to form a recess in the bottom of the hollow container by raising the base of the container and folding the side wall over about the finished bottom edge of the container to form an intermediate recess in the bottom with a double thickness of material around the recess, and then deforming the elastomeric mould portion to form the final required shape of the recess.
10. A method as claimed in Claim 9, in which the final required shape of the recess is formed by pressing the double thickness against the wall of the female mould.
11. Apparatus for performing the method of any preceding Claim comprising a female mould shell arranged to form the side wall of the container, having a punch assembly arranged for axial movement in the shell between an initial moulding position and a final moulding position to form the bottom of the container, the punch assembly including an elastomeric portion and means for deforming that portion when the punch is in its final moulding position to complete the formation of the container.
12. Apparatus as claimed in Claim 11, in which the elastomeric portion is formed of silicon rubber.
13. Apparatus as claimed in Claim 11 or 12, in which the punch assembly comprises a first member having a face arranged to form the base of the container, an elastomeric ring disposed around the first member adjacent that face and a sleeve movable on the first member to distort the elastomeric ring radially outwardly.
14. Apparatus as claimed in Claim 13 in which the elastomeric ring abuts a shoulder on said first member and said sleeve is arranged to squeeze the elastomeric ring against that shoulder.
15. Apparatus as claimed in Claim 13 or 14, in which said first member is formed with an abutment arranged to engage said mould shell to define said final moulding position.
16. Apparatus as claimed in Claim 13, 14 or 15 in which said punch assembly is movable between its positions by means of said sleeve.
17. Apparatus as claimed in Claim 16 in which said sleeve is arranged to engage the first member with lost motion which provides for the distortion of the elastomeric ring.
18. A method for the differential pressure thermoforming of a plastics material article substantially as herein described with reference to the accompanying drawings.
19. Apparatus for the differential pressure thermoforming of a plastics material article substantially as herein described with reference to the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7914402 | 1979-04-25 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2050925A true GB2050925A (en) | 1981-01-14 |
| GB2050925B GB2050925B (en) | 1983-08-03 |
Family
ID=10504766
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8013222A Expired GB2050925B (en) | 1979-04-25 | 1980-04-22 | Manufacturing of containers |
Country Status (5)
| Country | Link |
|---|---|
| DE (2) | DE3016045A1 (en) |
| ES (1) | ES8107085A1 (en) |
| FR (1) | FR2454891A1 (en) |
| GB (1) | GB2050925B (en) |
| IT (1) | IT1143149B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2602712B1 (en) * | 1986-08-18 | 1989-04-21 | Monoplast Sa | METHOD AND DEVICE FOR MANUFACTURING CONTAINERS BY THERMOFORMING AND CONTAINERS THUS OBTAINED |
| FR2640545B1 (en) * | 1988-12-16 | 1991-03-08 | Monoplast | METHOD AND DEVICE FOR THERMOFORMING HOLLOW OBJECTS BY STRETCHING-COMPRESSION |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1083034A (en) * | 1963-06-13 | 1967-09-13 | Dunlop Co Ltd | Manufacture of shaped articles by vacuum forming |
| GB1050358A (en) * | 1963-10-01 | |||
| DE1265397B (en) * | 1964-09-11 | 1968-04-04 | Alfons W Thiel | Method and device for producing thin-walled containers drawn from thermoplastic plastic film, in particular in the form of a cup |
| FR1545237A (en) * | 1966-06-04 | 1968-11-08 | Bebo Plastik Gmbh | Device for the production of hollow-bottomed plastic foil cups |
| FR1531739A (en) * | 1966-06-18 | 1968-07-05 | Bastert Werke | Hollow-bottomed tumbler, from sheet material, as well as method and device for manufacturing |
| DE1604457C3 (en) * | 1966-06-18 | 1974-07-18 | Bastert-Werke Gustav Bastert Gmbh, 4811 Heepen | Method and device for producing a bottom edge bead on deep-drawn cups |
| FR1538392A (en) * | 1966-06-30 | 1968-09-06 | Shell Int Research | Manufacture of thermoplastic articles |
| DE2034125A1 (en) * | 1970-07-09 | 1972-01-13 | Krueger E | Thermoplastics beaker deep drawing appts - with pneumatically controlled diaphragm piston for inversion of bombed base |
| FR2206166B1 (en) * | 1972-11-13 | 1976-01-30 | Solvay |
-
1980
- 1980-04-22 GB GB8013222A patent/GB2050925B/en not_active Expired
- 1980-04-24 IT IT48515/80A patent/IT1143149B/en active
- 1980-04-24 FR FR8009268A patent/FR2454891A1/en active Granted
- 1980-04-25 DE DE19803016045 patent/DE3016045A1/en not_active Ceased
- 1980-04-25 DE DE8011405U patent/DE8011405U1/en not_active Expired
- 1980-04-25 ES ES490935A patent/ES8107085A1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE3016045A1 (en) | 1980-11-13 |
| FR2454891A1 (en) | 1980-11-21 |
| ES490935A0 (en) | 1981-10-01 |
| DE8011405U1 (en) | 1980-09-04 |
| ES8107085A1 (en) | 1981-10-01 |
| GB2050925B (en) | 1983-08-03 |
| IT8048515A0 (en) | 1980-04-24 |
| FR2454891B1 (en) | 1985-03-29 |
| IT1143149B (en) | 1986-10-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19960422 |