Method of molding load-bearing articles from compressible cores and heat malleable coverings

• US 20050263044A1
• Filed: 06/01/2004
• Published: 12/01/2005
• Est. Priority Date: 06/01/2004
• Status: Active Grant

• Current Assignee: Novo Foam Products LLC
• Original Assignee: Novo Foam Products LLC
• Inventors: Lewis, Alan, Hedley, David, Bohan, Thomas, Bearse, Ed
• Granted Patent: US 7,413,698 B2
• Time in Patent Office: Days
• US Class Current: 108/57.250
• CPC Class Codes: B29C 2035/0822 using IR radiation
• CPC Class Codes: B29C 2791/001 Shaping in several steps
• CPC Class Codes: B29C 44/569 Shaping and joining components with different densities or hardness
• CPC Class Codes: B29C 48/0011 combined with compression moulding
• CPC Class Codes: B29C 48/0012 combined with shaping by internal pressure generated in the material, e.g. foaming
• CPC Class Codes: B29C 48/0017 combined with blow-moulding or thermoforming
• CPC Class Codes: B29C 48/12 Articles with an irregular circumference when viewed in cross-section, e.g. window profiles
• CPC Class Codes: B29C 51/12 of articles having inserts or reinforcements
• CPC Class Codes: B29C 51/165 combined with the feeding or the shaping of the lining or the labels by injection moulding B29C45/14008, B29C45/1418
• CPC Class Codes: B29C 51/427 Cooling of the material with a fluid blast
• CPC Class Codes: B29C 65/02 by heating, with or without pressure
• CPC Class Codes: B29C 65/08 using ultrasonic vibrations non-plastics element to plastics elements B29C65/645
• CPC Class Codes: B29C 65/10 using hot gases (e.g. combustion gases) or flames coming in contact with at least one of the parts to be joined
• 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 66/433 Casing-in, i.e. enclosing an element between two sheets by an outlined seam for bookbinding B42C11/06; for packaging B65B; by laminating B32B37/00; enclosing tubular articles between substantially flat elements B29C66/53261
• 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 66/727 being porous, e.g. foam
• CPC Class Codes: B29C 66/7315 Mechanical properties
• CPC Class Codes: B29C 66/73151 Hardness
• CPC Class Codes: B29C 66/73921 characterised by the materials of both parts being thermoplastics
• CPC Class Codes: B29C 66/8242 : Pneumatic or hydraulic drives using fluid pressure directly acting on the parts to be joined B29C66/8266
• CPC Class Codes: B29C 66/8322 : Joining or pressing tools reciprocating along one axis
• CPC Class Codes: B29C 66/83221 : cooperating reciprocating tools, each tool reciprocating along one axis
• CPC Class Codes: B29C 66/91411 : of the parts to be joined, e.g. the joining process taking the temperature of the parts to be joined into account
• CPC Class Codes: B29C 66/91645 : by steps
• CPC Class Codes: B29C 66/91931 : in explicit relation to the fusion temperature or melting point of the material of one of the parts to be joined
• CPC Class Codes: B29K 2023/04 : Polymers of ethylene
• CPC Class Codes: B29K 2023/06 : PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/0633 : LDPE, i.e. low density polyethylene
• CPC Class Codes: B29K 2023/065 : HDPE, i.e. high density polyethylene
• CPC Class Codes: B29K 2023/10 : Polymers of propylene
• CPC Class Codes: B29K 2023/12 : PP, i.e. polypropylene
• CPC Class Codes: B29K 2025/04 : Polymers of styrene
• CPC Class Codes: B29K 2025/06 : PS, i.e. polystyrene
• CPC Class Codes: B29K 2025/08 : Copolymers of styrene, e.g. AS or SAN, i.e. acrylonitrile styrene B29K2055/02 takes precedence
• CPC Class Codes: B29K 2067/00 : Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2069/00 : Use of PC, i.e. polycarbonates or derivatives thereof, as moulding material
• CPC Class Codes: B29K 2071/12 : PPO, i.e. polyphenylene oxide; PPE, i.e. polyphenylene ether
• CPC Class Codes: B29K 2105/04 : cellular or porous
• CPC Class Codes: B29K 2995/007 : Hardness
• CPC Class Codes: B29K 2995/0089 : Impact strength or toughness
• CPC Class Codes: B29L 2009/00 : Layered products
• CPC Class Codes: B29L 2031/7178 : Pallets
• CPC Class Codes: B65D 19/0018 : and each contact surface having a discrete foot-like shape
• CPC Class Codes: B65D 2519/00034 : Plastic
• CPC Class Codes: B65D 2519/00069 : Plastic
• CPC Class Codes: B65D 2519/00273 : made of more than one piece
• CPC Class Codes: B65D 2519/00288 : made of one piece
• CPC Class Codes: B65D 2519/00318 : made of one piece
• CPC Class Codes: B65D 2519/00338 : contact surface having a discrete foot-like shape
• CPC Class Codes: B65D 2519/00562 : chemical connection, e.g. glued, welded, sealed
• CPC Class Codes: B65D 2519/00835 : Integral

Abstract

Load-bearing article are manufactured from shape defining compressible cores and thermoplastic shells. The manufacture of these articles requires specific methods and tools. Articles that can be manufactured using these methods include relatively lightweight pallets with high load-bearing capacity.

Claims

3-1. The method according to claim 1, wherein said core member and said first and said second thermoplastic sheets comprise materials that bond to one another when said materials are heated and held in contact with one another.

24. An apparatus for forming a load-bearing article having a shape defining compressible core member and a thermoplastic external shell, said apparatus comprising:

a first molding tool having a first perforated surface;

a vacuum source connected to said perforations in said first molding tool for reversibly holding said core member;

a second molding tool having a convex interior surface;

a heating component for heating thermoplastics;

a first device for positioning said a first thermoplastic sheet between said core member attached to said first molding tool and said concave surface of said second molding tool;

a mechanism for compressing said first sheet and said core member into contact with said concave surface of said second molding tool;

a mechanism for withdrawing said first molding tool after said first sheet is placed in contact with said second molding tool

a device for positioning said second heated thermoplastic sheet between said core member attached to first heated thermoplastic sheet and said second molding tool and said first molding tool;

a mechanism for compressing said first sheet, said core member, and said second sheet together; and

a device for welding portions of said first and second sheets in contact with one another together.

25. The apparatus according to claim 24, wherein said mechanisms for compressing and withdrawing, are the same mechanism and said mechanism is powered by a drive means selected from the group consisting of:

pneumatic, hydraulic, and mechanical drivers.

26. The apparatus according to claim 24, further including:

a means of cooling said article to accelerate the formation of bonds between portions of said article in contact with one another.

27. The apparatus according to claim 26, wherein said means for cooling is a source of flowing air directed towards said article.

28. The apparatus according to claim 24, further including,

a steam chest molding machine for shaping said shape forming compressible core member.

29. The apparatus according to claim 24, wherein said devices for positioning said first and said second heated thermoplastic sheets are clamping frames having a perimeter larger than the perimeter of said first and said second molding tools.

30. The apparatus according to claim 24, further including a pinching mechanism for applying directed pressure to portions of said first and said second heated thermoplastic sheets which are in contact with one another.

31. The apparatus according to claim 24, further including a means for applying a thermo-activated adhesive to the surfaces of said core member before said core member is compressed between said first and said second heated sheets.

32. A load-bearing article, said article comprising:

a shape defining compressible core member, having at least one surface including a convex feature and a core member perimeter; and

a thermoplastic shell having a shell interior and a shell edge, wherein said shell includes a first heated pliable thermoplastic sheet having an interior shaped by said convex surface of said core member and a first sheet edge extending outside of said core member perimeter, and a second heated pliable thermoplastic sheet having a second sheet interior and second sheet edge extending outside of said core member perimeter, said article is formed by compressing said core member between the interiors of said first and said second sheets, and bonding the edges of said first and said second sheets to one another to form said edge of said shell, said core member is compressed within said shell formed by said first, and said core member bonds to the said interior surface of said shell.

33. The article according to claim 32, further including,

a thermo-activated adhesive layer between said core member and said thermoplastic shell.

34. The article according to claim 32, wherein said core member is further compressed as said thermoplastic shell cools and contracts.

35. The article according to claim 32, wherein the volume of said core member before it is compressed is larger than the volume of the thermoplastic shell.

36. The article according to claim 32, wherein said core member comprises compressible material selected from the group consisting of:

Expandable Polystyrene (PSE), a blend of polyphenylene ether (PPE) and polystyrene (PS) impregnated with pentane, a blend of polyyphenyene ether (PPE) and polystyrene (PS) impregnated with pentane, Polyethylene (PE), and Polypropylene.

37. The article according to claim 32, wherein said thermoplastic sheets comprise a thermoplastic material selected from the group of thermoplastic materials consisting of:

Polyproplyene/ Polyproplyene composite, Polycarbonate (PC), High Impact Polystyrene (HIPS), Low Density Polyethylene (LDPE), High Density Polyethylene (HDPE), Polypropylene (PP), and Polyphenyle Ether alloyed with High Impact Polystyrene.

38. The article according to claim 32, wherein said core member includes Expandable Polyporopylene (EPP) and said thermoplastic shell includes TPO.

39. The article according to claim 38, wherein said TPO further includes talc, calcium carbonate, and pressing aids.

40. The article according to claim 38, wherein the thickness of said TPO ranges from about 0.04 to about 0.08 inches.

41. The article according to claim 38, wherein the said a first portion of the thermoplastic shell is about 0.08 inches thick and a second portion of the thermoplastic shell is about 0.04 inches thick.

42. The article according to claim 32, wherein said EPP has a density ranging from about 1.9 to about 5.0 pounds per cubic foot (lbs./ft.³).

43. The article according to claim 32, wherein said EPP has a density of about 1.9 per cubic foot (lbs./ft.³).

44. The article according to claim 32, wherein said core member is shaped by steam chest molding before said core member is used to shape and from said load-bearing article.

45. The article according to claim 32, wherein said article can be used in items selected from the list consisting of:

vehicle panels, bumpers, helmets, security barriers, casings for appliances, coolers, doors, packing crates, and pallets.

46. A pallet comprising:

a shape defining compressible core member, having a first core member surface, a second core member surface, and a core member perimeter, wherein said second core member surface is substantially flat, said core member first surface includes convex features, and said core member substantially determines the shape of said pallet.;

a thermoplastic shell having a shell interior and a shell edge, wherein said article is formed by a twin sheet molding process, said shell includes a first heated pliable thermoplastic sheet having an interior and a first sheet edge, said first sheet edge extending outside of said core member perimeter, and a second heated pliable thermoplastic sheet having a second sheet interior and second sheet edge extending outside of said core member perimeter, said article is formed by compressing said core member between the interiors of said first and said second sheets, and bonding the edges of said first and said second sheets to one another to form said edge of said shell, said core member is compressed within said shell formed by said first, and said core member bonds to the said interior of said shell.

47. The pallet according to claim 46, wherein the volume of said shape defining compressible core member is larger before said core member is compressed between said first and said second sheets than it is after said pallet is formed.

48. The pallet according to claim 47, wherein said compressible core member and said first and said second thermoplastic sheets are chemically compatible with one another, and heat transfer between said heated first and second thermoplastic sheets and said core member promotes bonding of said core member to portions of said sheet in contact with said core member.

49. The pallet according to claim 47, further including a layer of thermo-activated adhesive between said core member and said interior of said shell.

50. The pallet according to claim 47, comprising:

a deck having an upper surface and a lower surface;

a front,

a rear,

a first side;

a second side; and

a plurality of support legs attached to said deck wherein said upper surface of said deck is substantially flat and said supports are contiguous with said lower surface of said pallet and said front and said rear are parallel to one another and perpendicular to said first and said second sides.

51. The pallet according to claim 50, wherein the number of said support legs is greater than or equal to four and less than or equal to nine.

52. The pallet according to claim 47 wherein each support leg is shaped as a conical oval, said support leg having a top portion extending from said lower surface of said deck, the top portion of said support leg is wider than the portion of said support leg furthest from said deck.

53. The pallet according to claim 49, wherein the shorter axis of said conical oval shaped support leg is parallel to said front of said pallet.

54. The pallet of according to claim 47, wherein said first thermoplastic sheet and second thermoplastic sheet are directly bonded to one another at a plurality of positions located between adjacent support legs.

55. The pallet according to claim 54, wherein said bonding regions between said first and said second sheets located between said edges of said pallet are located one between each pair of leg supports.

56. The pallet according to claim 47,further including at least one groove in said lower surface of said deck deck, each said groove is parallel said edges of said pallet.

57. The pallet according to claim 56, wherein and each set of grooves are positioned between said rows of support legs.

58. The pallet according to claim 47, wherein said core member comprises Expandable Polyporopylene (EPP) and said first and said second thermoplastic sheets comprise thermoplastic olefin (TPO).

59. The pallet according to claim 58, wherein said TPO further includes talc, calcium carbonate, and pressing aids.

60. The pallet according to claim 58, wherein the thickness of said TPO ranges from about 0.04 to about 0.08 inches.

61. The pallet according to claim 58, wherein the said first thermoplastic sheet is about 0.04 inches thick and the second thermoplastic sheet is about 0.08 inches thick.

62. The pallet according to claim 58, wherein said EPP has a density ranging from about 1.9 to about 5.0 pounds per cubic foot (lbs./ft.³).

64. The pallet according to claim 58, wherein said EPP has a density of about 1.9 per cubic foot (lbs./ft.³).