Containers and cans and method of and apparatus for producing the same

• US 5,115,938 A
• Filed: 05/03/1989
• Issued: 05/26/1992
• Est. Priority Date: 10/30/1987
• Status: Expired due to Term

• Current Assignee: ZapatA Innovative Closures, Inc.
• Original Assignee: Tri-Tech Systems International, Inc.
• Inventors: Thompson, Mortimer S.
• Primary Examiner(s): Foster, Jimmy G.
• Application Number:
  US07/347,263
• Time in Patent Office: 1,119 Days
• Field of Search: 29/506, 29/509, 29/510, 53/486, 156/69, 156/272.2, 220/66-68, 220/79, 220/309, 220/359, 220/240, 220/DIG. 16, 220/611, 220/614, 220/618, 220/619, 220/620, 264/248, 264/249, 413/1, 413/6, 413/41, 229/5.5, 229/5.6, 229/5.7, 229/125.35
• US Class Current: 220/618
• CPC Class Codes: B21D 51/30 Folding the circumferential seam
• CPC Class Codes: B29C 57/12 Rim rolling
• CPC Class Codes: B29C 65/56 using mechanical means or mechanical connections, e.g. form-fits
• CPC Class Codes: B29C 65/568 using a swaging operation, i.e. totally deforming the edge or the rim of a first part to be joined to clamp a second part to be joined
• CPC Class Codes: B29C 66/0242 Heating, or preheating, e.g. drying B29C66/3464 takes precedence
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/542 joining hollow covers or hollow bottoms to open ends of container bodies
• CPC Class Codes: B29C 66/545 one hollow-preform being placed inside the other
• CPC Class Codes: B29C 66/63 Internally supporting the article during joining B29C66/49 takes precedence
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/8322 Joining or pressing tools reciprocating along one axis
• CPC Class Codes: B29K 2023/06 PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/12 PP, i.e. polypropylene
• CPC Class Codes: B29K 2025/06 PS, i.e. polystyrene
• CPC Class Codes: B29K 2027/06 PVC, i.e. polyvinylchloride
• CPC Class Codes: B29K 2033/20 PAN, i.e. polyacrylonitrile
• CPC Class Codes: B29K 2059/00 Use of polyacetals , e.g. POM, i.e. polyoxymethylene or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2067/003 PET, i.e. poylethylene terephthalate
• CPC Class Codes: B29K 2069/00 Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2077/00 Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• CPC Class Codes: B65D 11/02 : of curved cross-section thermally insulated B65D81/3813
• CPC Class Codes: B65D 17/08 : Closures secured by folding or rolling and pressing
• CPC Class Codes: B65D 25/00 : Details of other kinds or types of rigid or semi-rigid containers
• CPC Class Codes: Y10S 220/16 : Pressure indicators

Abstract

A container or can having a body and end portion which include free ends comprising plastic materials and which are joined and sealed by cooperatively curling juxtapositioned free ends. The method end apparatus of the invention forms the body portion with an opening surrounded by a free end suitable for curling and forms the end portion with a central portion surrounded by a free end suitable for curling. The container body and end portion are joined by juxtaposing their free ends for forming a plurality of walls, then the plastic in at least one of the free ends is provided in a condition at the time of curling which allows stress and related elastic strain and memory to be imparted to the plastic, followed by curling with a curling tool to intimately engage the ends and concurrently curl the perimeters thereof into a tightly curled configuration, wherein at least the one free end includes internal stress and related strain and memory for providing a seam of integrity and reliability.

Claims

1. A container comprising:

a body having a free end of plastic,

and an end portion having a central portion and a free end of plastic about its perimeter, and

said free ends being in juxtaposition and continuously flexed to provide a curl to form a plurality of curled walls which are joined together as a seam, wherein at least one of said curled free ends includes internal stresses and related strain and memory along its length for providing a seam of integrity and reliability by maintaining engagement therebetween wherein during curling at least one of the free ends are maintained at a temperature below its Vicat softening point.

2. The container of claim 1, wherein each of said curled free ends includes internal stresses and related strain and memory for providing a seam of integrity and reliability by maintaining engagement therebetween.

3. The container of claim 1, wherein said curled free ends have a cross sectional shape of a coil.

4. The container of claim 1, wherein said end portion has a central portion and peripheral skirt including said free end.

5. The container of claim 1, wherein said central portion has a concave cross sectional shape.

6. The container of claim 1, wherein one of said free ends is longer than any other free end.

7. The container of claim 1, wherein said body includes an inwardly extending projection spaced from said free end thereof for positioning said end portion with said body.

8. The container of claim 1, wherein the free end of said end portion is force fitted within the free end of said container body.

9. The container of claim 1, wherein the uncurled portions of said free ends apply hoop stresses to said curled free ends to increase the urging of the curled free ends together.

10. A container comprising:

a body having a free end including plastic,

an end portion having a central portion and a free end about its perimeter including plastic, and

said free ends being tapered, juxtaposed and curled to form a plurality of curled walls which are joined together as a seam, wherein at least one of said curled free ends includes internal stresses and related strain and memory for providing a seam of integrity and reliability by maintaining engagement therebetween.

11. A method of forming a container having a body and an end portion with free ends about their perimeters, wherein the free ends include a plastic and are adapted to be curled, comprising:

juxtaposing the free ends,

maintaining plastic in at least one of the juxtaposed free ends at a temperature which is below its Vicat Softening Point at the time of curling of the free ends so that at least one of the free ends can develop stress and related elastic strain and elastic memory during curling, and

concurrently and circumferentially engaging at least one of the juxtaposed free ends about its perimeter with a die and progressively curving the juxtaposed free ends into a multi-wall curled configuration wherein plastic in at least one free end maintained at a temperature below its Vicat Softening Point during curling develops stress and related strain and elastic memory to thereby produce and maintain engagement therebetween after disengagement between the die and the perimeter of the juxtaposed curled free ends.

12. The method of claim 11, wherein the end portion is formed with an upper free end and a lower free end and the body has a transitional recess adjacent its free end, and

wherein the upper free end is concurrently curled with said body free end to produce said multiwall curled configuration and the lower free end is engaged by said body recess to curl and produce a sealing engagement therewith.

13. The method of claim 11, wherein the body is formed with an outer free end and an inner free end and the end portion has a lower transitional recess adjacent its free end, and

wherein the outer free end is concurrently curled with said end portion free end to produce said multiwall curled configuration and the inner free end is engaged by said end portion recess to curl and produce a sealing engagement therewith.

15. The method of claims 11 or 14, wherein the plastic of the free ends comprises polymers, and wherein the physical characteristics of the polymer in at least the one of said free ends is alterable by producing stress and related strain and memory therein as the free ends are curled.

16. The method of claims 11 or 14, comprising progressively curling the free ends inwardly and vertically.

17. The method of claims 11 or 14, comprising progressively curling the free ends outwardly and vertically.

18. The method of claim 17, wherein the curled free ends have a cross sectional shape of a coil.

19. The method of claims 11 or 14, comprising tapering the free ends to control compression thereon and to facilitate curling thereof.

20. The method of claims 11 or 14, comprising forming the body with an inwardly extending projection spaced from the free end thereof for positioning the end portion with the body.

21. The method of claims 11 or 14, comprising forming the free ends of the body and end portion with different levels of elastic strain in the plastic materials for intimate contact between the free ends in the curled configuration.

22. The method of claims 11 or 14, comprising heating at least the outer free end as the free ends curl.

23. The method of claims 11 or 14, comprising crimping, creasing or compressing the curled free ends of the body and end portion.

24. The method of claims 11 or 14, comprising bonding the free ends of the body and end portion prior to or after curling.

25. The method of claims 11 or 14, comprising forming the free ends of the body and end portion in a direction which is substantially along the longitudinal axis of the body.

26. The method of claims 11 or 14, comprising forming the free ends of the body and end portion in a direction which is substantially radial to the direction of the longitudinal axis of the container.

27. The method of claims 11 or 14, comprising bonding the curled free ends to the body of the container or to the central portion of the end portion.

28. The method of claims 11 or 14, comprising forming a concave recess between the free end and central portion of the end portion which abuts and restrains the curled free ends.

29. The method of claims 11 or 14, comprising forming a concave recess between the free end and central portion of the end portion which exerts a compressive component against the curled free ends.

30. The method of claims 11 or 14, comprising forming the central portion with a concave configuration which can be flexed upwardly by internal pressure to exert a compressive component against the curled free ends.

31. The method of claims 11 or 14, comprising forming the central portion with a convex configuration which can be flexed downwardly upon vacuum packaging to exert a compressive component against the curled free ends.

32. The method of claims 11 or 14, comprising forming the central portion with a convex configuration which can be flexed downwardly to exert a compressive component against a transitional portion between the can body and its free end.

33. The method of claims 11 or 14, comprising forming a curved central end portion having radial depressions or liens of weakness so that the central portion of the end portion can exert a compressive component on the curled free ends in response to a pressure differential thereon.

34. The method of claims 11 or 14, further comprising:

circumferentially and elastically stretching uncurled portions of the free ends as the free ends are curled so that upon completion of curling the uncurled portions of the free ends elastically recover and further urge the curled free ends together.

46. The method of claims 11, 14, 35, 40 or 45, further comprising curling the free ends in a direction which orients the plastic in the outer surface of the free ends in the direction of curling to strengthen said surface.

47. The method of claim 46, wherein plastic in the free ends is placed in compression which also strengthens said plastic.

48. The method of claims 11, 14, 35, 40 or 45, further comprising heating the free ends after curling to reduce stress therein.

49. The method of claims 11, 14, 35, 40 or 45, further comprising:

forming a portion of the container having an inwardly extending dome of plastic with an area of said dome which has less strength that other portion of said dome to facilitate inverting and reinverting of the plastic dome in response to pressure changes within or without the container.

14. A method of forming a container having a body and an end portion with free ends about their perimeter, wherein the free ends include a plastic and are adapted to be curled, comprising:

juxtaposing the free ends,

maintaining plastic in at lest one of the juxtaposed free ends at a temperature which is below its Vicat Softening Point at the time of curling of the free ends so that at least one of the free ends can develop stress and related elastic strain and elastic memory during curling, and

concurrently engaging at least one of the juxtaposed free ends about its perimeter with a die and progressively curving the juxtaposed free ends as at least the engaged free end moves along and away from the engaging portion of the die wherein engagement with the die causes the development of stress and related strain and elastic memory in the plastic in at least one of the free ends while said free end is maintained at a temperature below its Vicat Softening Point, whereupon the stress and related strain and elastic memory in at least said one free end urges the free ends to continue to curl into a multi-wall curled configuration as the engaged free end moves away from the die to thereby produce and maintain sealing engagement therebetween.

35. A method of forming a container having a body and an end portion with free ends about their perimeters, wherein the free ends include a plastic and are adapted to be curled, comprising:

forming the body having an opening therein and the free end;

forming the end portion including a central portion, a wall about the perimeter of the central portion, a free end about the end portion and spaced from the wall portion, and a transitional portion between and connected to the wall and free end forming a recess therebetween,

juxtaposing the free ends of the body and end portion to form a plurality of walls therebetween,

maintaining plastic in at least one of the juxtaposed free ends at a temperature which is below its Vicat Softening Point at the time of curling of the free ends so that at lest one of the free ends can develop stress and related elastic strain and elastic memory during curling, and

concurrently and circumferentially engaging at least one of the juxtaposed free ends about its perimeter with a die and progressively curving the juxtaposed free ends into a multi-wall curled configuration in the recess of the end portion, and wherein plastic in at least the one free end maintained at a temperature below its Vicat Softening Point during curling develops stress and related strain and elastic memory to thereby produce and maintain engagement therebetween after disengagement between the die and the perimeter of the juxtaposed curled free ends.

36. The method of claim 35, wherein the free end of the body is longer than the free end of the end portion, and wherein the free end of the body is the outer wall of the juxtaposed free ends.

37. The method of claim 36, wherein the outer free end of the body is heated to soften its outer surface as the free ends are curled.

38. The method of claim 37, wherein the walls forming the recess in the end portion includes annular projections therein which produce complementary indentations in the softened outer surface of the free end of the body when the free ends are curled.

39. The method of claim 35, further comprising forming the body with a wall about the opening and a transitional portion between and connected to the wall and free end, wherein the transitional portions of the body and end portion are formed with at least one complementary projection and groove which are brought into engagement with each other as the free ends are curled.

40. A method of forming a container having two components comprising a body and an end portion,

forming one component with inner and outer free ends,

forming the other component with a free end about is perimeter, wherein the free end includes a plastic material and is adapted to be curled,

maintaining plastic in at least one of the juxtaposed free ends at a temperature which is below its Vicat Softening Point at the time of curling of the free ends so that at least one of the free ends can develop stress and related elastic strain and elastic memory during curling, and

concurrently and circumferentially engaging at least one of the juxtaposed free ends about its perimeter with a die and progressively curving the juxtaposed free ends into a multi-wall curled configuration wherein plastic in at least the one free end maintained at a temperature below its Vicat Softening Point during curling develops stress and related strain and elastic memory to thereby produce and maintain engagement therebetween after disengagement between the die and the perimeter of the juxtaposed curled free ends.

41. The method of claim 40, wherein the free end of said other component is curved at its outer end for juxtapositioning said outer end between the free ends of said one component.

42. The method of claim 41, wherein the outer free end of said one component is longer then the other free ends.

43. The method of claim 42, wherein the free end of said other component is adjacent to the inner free end of said one component when the free ends are juxtaposed.

44. The method of claim 43, wherein the curling is accomplished by a die which initially engages and begins to curl the longer outer free end of said one component followed by curling all of the free ends and the longer free end is curled into contact with the curved outer end of said other component.

45. A method of forming a container from two components including a body and an end portion, comprising:

forming one component with inner and outer free ends with a recess therebetween, wherein the free ends include plastic materials and are adapted to be curled,

forming the other component with substantially opposing upper and lower free ends which form recesses with the adjacent portions of said other component, and wherein the free ends include plastic materials and are adapted to be curled,

juxtaposing the free ends of said components wherein one of the free ends of said one component is adjacent the lower free end of the other component for forming lower curled walls, and wherein the other free end of said one component is adjacent to the upper free end of the said other component for forming upper curled walls, and

concurrently and circumferentially engaging at least one of the juxtaposed free ends of each component about its perimeter with a die and progressively curving the juxtaposed free ends into a plurality of lower and upper curled walls, wherein plastic in at least each of the one free end maintained at a temperature below its Vicat Softening Point during curling develops stress and related strain and elastic memory to thereby produce and maintain engagement between the walls after disengagement between the die and the perimeter of the juxtaposed curled free ends.