Method and apparatus for fabricating thermoplastic containers

• US 4,072,549 A
• Filed: 04/30/1976
• Issued: 02/07/1978
• Est. Priority Date: 11/23/1973
• Status: Expired due to Term

• Current Assignee: Owens-Illinois Pty Limited (O-I Glass, Inc.)
• Original Assignee: Owens-Illinois Incorporated (O-I Glass, Inc.)
• Inventors: Amberg, Stephen W., Amberg, Ralph G.
• Primary Examiner(s): Van Horn, Charles E.
• Assistant Examiner(s): Kittle, John E.
• Application Number:
  US05/681,855
• Time in Patent Office: 648 Days
• Field of Search: 156/69, 156/84, 156/85, 156/86, 156/184, 156/187, 156/189, 156/194, 156/198, 156/215, 156/217, 156/218, 156/285, 156/304, 156/322, 156/443, 156/446, 156/497, 156/499, 156/272 , 156/277, 264/230, 264/296, 264/342 R, 264/310, 264/320, 264/322, 93/36.1, 93/36.5 R, 93/36.8
• US Class Current: 156/86
• CPC Class Codes: B29C 53/42 using internal forming surfaces, e.g. mandrels
• CPC Class Codes: B29C 61/025 for the production of hollow or tubular articles
• CPC Class Codes: Y10T 156/1033 Flexible sheet to cylinder lamina
• CPC Class Codes: Y10T 156/1038 Hollow cylinder article

Abstract

A cup or other nestable container is formed from two continuous web stocks of thermoplastic material, particularly an expanded thermoplastic material. A rectangular blank to form the sidewall of the container is severed from a first web stock, and formed into a cylindrical sleeve with the end portions thereof joined to one another in a liquid-tight seam extending the full height thereof. A circular bottom closure disc is cut from a second web stock and transferred to a recessed top of a forming mandrel carried on a continuously-moving turret. The cylindrical sleeve is positioned about the forming mandrel, which carries the sleeve and bottom closure disc to various subassemblies that cooperate with the forming mandrel to produce a finished cup. The cylindrical sleeve is forced downwardly into a heated rimming die positioned adjacent the lower edge of the forming mandrel to cause the lower edge of the sleeve to be rimmed. The cylindrical sleeve is shrunken to conform to the side contour of the forming mandrel, and the upper end of the sleeve extends inwardly to provide an inturned position overlying the periphery of the bottom closure disc. The bottom closure disc and inturned portion are sealingly joined and contoured to finish the bottom of the container.

Claims

1. The method of fabricating a cup-like container comprising the steps of:

providing a rectangular blank of heat-shrinkable thermoplastic material;

winding said blank about a generally cylindrical wrapping member to provide a tubular shape with a trailing end portion of said blank overlapping a leading end portion;

transferring said tubular shape axially on said wrapping member;

forming a cylindrical sleeve by joining said overlapping end portions of said tubular shape to one another in a liquid-tight seam extending the full length of said sleeve;

providing an upwardly facing mandrel having an enlarged diameter portion at its lower end, the outer surface of said mandrel having the configuration of the inner surface of the sidewall of said container, and having a circumferentially extending concave rimming die portion located at said lower end;

heating said mandrel rimming die portion to an elevated temperature;

telescoping said cylindrical sleeve over said mandrel;

forcing said sleeve axially downwardly about said lower end and into said mandrel rimming die portion to cause a portion of the lower end of the sleeve to be turned upwardly;

rotating said mandrel as said sleeve is forced downwardly;

advancing a complementary rimming die in juxtaposition with said mandrel rimming die portion during rotation of said mandrel to cause said upwardly turned portion to be directed inwardly to form a curled rim;

subsequently exposing the sleeve to heat while it is in position over the mandrel to cause it to shrink so that the inner surface conforms to the outer surface of the mandrel;

fusing a bottom closure disc to the end of said shrunken sleeve opposite said rim to form a liquid-tight seal and thus complete said container; and

removing said container from said mandrel.

2. The method according to claim 1, further comprising the step of continuously rotating said mandrel during the rimming, heating and bottom sealing steps.

3. The method according to claim 1 wherein said blank winding step is performed in a first processing path along which said sleeve is transferred axially and said telescoping step is performed by translationally rotating said sleeve from said first processing path to a mandrel moving along a second processing path.

4. The method according to claim 3 wherein said second processing path is spaced vertically below said first processing path and wherein said telescoping step is performed by translationally rotating said sleeve through an arc tangential to said first and second paths.

5. The method according to claim 1 wherein said winding step is performed by sealingly positioning said wrapping member coaxially about a support member to provide an annular chamber therebetween, providing a plurality of longitudinally spaced vacuum ports in said wrapping member in communication with said annular chamber;

rotating said wrapping member relative to said support member to position said ports in a first position;

feeding the leading end of said blank into overlying relationship with said wrapping member diametrically opposite said ports while said ports are in said first position;

rotating said wrapping member 540°

relative to said support in the direction of feed of said blank;

supplying vacuum to said annular chamber and ports as said ports rotate into underlying relationship to said leading end to affix said end to said wrapping member, whereby said blank is wound about said wrapping member; and

terminating said vacuum to said annular chamber after said blank has been wound.

6. The method according to claim 5 wherein said vacuum supplying and terminating steps are performed by providing a passage way in said support member in communication with said annular chamber;

moving a vacuum applying member receiving vacuum from a source into and out of communication with said passageway in timed relationship with the rotation of said wrapping member.

7. The method according to claim 1 further including the steps of providing a tamping plate having an aligning cam surface thereon adapted to be inserted within said sleeve;

positioning said plate in a clearance position away from the top of said mandrel during said placing step to provide free access to said mandrel;

moving said plate into axial alignment with the top of said mandrel;

lowering said plate relative to said mandrel into engagement with the upper end of said sleeve, whereby said cam surface aligns said sleeve axially with said mandrel; and

further lowering said plate to force said lower end of said sleeve into said mandrel rimming die.

8. The method according to claim 1 wherein said disc is provided by reciprocating a cutter through a web stock in a cutting path;

transferring said disc to a transfer path;

conveying said disc along said transfer path to a position in alignment with said mandrel; and

transferring said disc from said transfer path to said mandrel.

9. The method according to claim 8 in which said mandrel is moved along a closed path;

and wherein the step of transferring said disc to said mandrel is performed by conveying said disc along an elevated transfer path into vertical register with the path of the top of said mandrel;

synchronizing the movement of said disc and mandrel; and

transferring said disc downwardly from said conveyor path to the top of said mandrel.

10. The method according to claim 9 wherein the step of conveying said disc along an elevated path is performed by supporting the periphery of said disc from beneath and moving it in a horizontal orientation parallel to the tops of said mandrel along an arcuate conveyor path.

11. The method according to claim 10 wherein the step of transferring said disc downwardly involves rotating a finger into engagement with the top of said disc causing said disc to be flexed and thereby released from said conveyor.

12. The method according to claim 1, wherein said thermoplastic material is a compressible foam sheet and overlapping end portions are joined by directing heated air in the range of about 775°

-825°

F. between the confronting surfaces of said overlapping end portions to soften said thermoplastic material and compressing said softened ends to form a liquid-tight seam of reduced thickness therebetween.

13. The method according to claim 12 wherein said softened end portions are compressed as they pass progressively between the nip of two rotating rollers.

14. The method according to claim 1, wherein the step of exposing said sleeve to heat is accomplished by conveying said mandrel past heat sources disposed adjacent to and at the elevation of the path of said sleeve.

15. The method according to claim 1 comprising the further step of preheating the entire mandrel to an elevated temperature prior to reception of said sleeve.