Forming mold cavities

• US 6,258,311 B1
• Filed: 02/25/1999
• Issued: 07/10/2001
• Est. Priority Date: 08/25/1997
• Status: Expired due to Term

• Current Assignee: Velcro BVBA
• Original Assignee: Velcro Industries BV (Chartwell Industries Ltd)
• Inventors: Banker, Shawn C., Kingsford, Howard, Buzzell, Keith G., Parshley, Joseph K., Gallant, Christopher M., Babineau, James W., Harvey, Andrew C., Dowd, Clinton, Pollard, Samuel W., Filion, Scott M., Jens, Stephen C., Jacobs, Martin I., Fryklund, Gilbert G.
• Primary Examiner(s): Silbaugh, Jan H.
• Assistant Examiner(s): Eashoo, Mark
• Application Number:
  US09/259,182
• Time in Patent Office: 866 Days
• Field of Search: 264/220, 264/221, 264/81, 264/317, 425/363, 425/471, 249/116, 204/192.15, 205/70, 205/158, 205/164, 205/165, 205/167, 205/169, 205/180, 205/182, 427/331, 427/237, 427/252, 427/404
• US Class Current: 264/220
• CPC Class Codes: A44B 18/0049 obtained by moulding processes compression moulding or articles of indefinite length characterised by the shape of the surface B29C43/222; screen moulding B29C67/08
• CPC Class Codes: B29C 2043/023 having a plurality of grooves
• CPC Class Codes: B29C 2043/3678 on cylindrical supports with moulds or mould cavities provided on the periphery
• CPC Class Codes: B29C 2043/461 the rollers having specific surface features
• CPC Class Codes: B29C 2043/465 having one or more cavities, e.g. for forming distinct products
• CPC Class Codes: B29C 33/302 Assembling a large number of mould elements to constitute one cavity
• CPC Class Codes: B29C 33/3857 by making impressions of one or more parts of models, e.g. shaped articles and including possible subsequent assembly of the parts
• CPC Class Codes: B29C 41/02 for making articles of definite length, i.e. discrete articles
• CPC Class Codes: B29C 41/26 by depositing flowable material on a rotating drum
• CPC Class Codes: B29C 41/28 by depositing flowable material on an endless belt
• CPC Class Codes: B29C 43/222 characterised by the shape of the surface
• CPC Class Codes: B29C 43/46 Rollers
• CPC Class Codes: B29C 45/2673 with exchangeable mould parts, e.g. cassette moulds B29C45/1756 takes precedence
• CPC Class Codes: B29C 45/2675 Mounting of exchangeable mould inserts
• CPC Class Codes: B29C 59/025 Fibrous surfaces with piles or similar fibres substantially perpendicular to the surface
• CPC Class Codes: B29L 2031/729 Hook and loop-type fasteners

Abstract

A method for producing a multiplicity of fastener element molding cavities extending from a mold surface, for molding a plastic product having fastener elements integrally molded with and extending from a product base, and a mold so produced. The mold cavities are formed by depositing multiple layers of plating material on a workpiece in a predetermined pattern selected to produce a desired mold cavity shape, or by depositing a thick stratum of plating material over an array of fastener elements and then removing the fastener elements to leave shaped cavities within the plating material. The mold may be in the form of a roll or belt for continuous processing, or in any form for discrete injection molding. Molds having fastener element cavities defined by rigid cast materials are also disclosed.

Claims

1. A method of producing a mold surface defining an array of blind cavities extending therefrom, each cavity having a shape of a hook fastener element, for molding a corresponding array of hook fastener elements integrally with and extending from a fastener product base, the method comprising the steps of

depositing a layer of plating material on a master having an array of hook fastener elements extending to a given height from a surface thereof, the layer of plating material being deposited to a thickness greater than the height of the hook fastener elements of the master;

and thereafter

removing the master from the plating material, leaving the array of blind cavities extending into the plating material from said mold surface, the array of blind cavities configured for integrally molding a corresponding array of hook fastener elements with a product base formed on said mold surface.

2. The method of claim 1 wherein the cavities are hook-shaped.

3. The method of claim 1 wherein the deposited plating material forms a cylindrical mold sleeve with the blind cavities extending inward from its outer surface.

4. The method of claim 3 wherein at least some of the blind cavities define crooks extending in the axial direction of the mold sleeve.

5. The method of claim 4 wherein all of the blind cavities define crooks extending in the axial direction of the mold sleeve.

6. The method of claim 4 wherein the blind cavities extending in the axial direction of the mold sleeve are arranged in rows, the crooks of cavities of alternating sets of said rows extending in opposite directions.

7. The method of claim 3 wherein the blind cavities are arranged in an array extending about the entire circumference of the mold sleeve.

8. The method of claim 3 wherein the blind cavities are arranged in rows which spiral about the circumference of the mold sleeve.

9. The method of claim 3 wherein the master is in the form of a flexible strip of fastener product having an array of fastener elements integrally molded with a strip-form base, the method comprising, before the step of depositing plating material, the step of attaching the master to an inner cylindrical surface of a plating fixture.

10. The method of claim 9 wherein at least some of the fastener elements of the master extend in the axial direction of the cylindrical surface of the plating fixture.

11. The method of claim 9 wherein the fastener elements of the master are arranged in rows that spiral about the circumference of the cylindrical surface of the plating fixture.

12. The method of claim 3 wherein the master is in the form of multiple flexible strips of fastener product, each having an array of fastener elements integrally molded with a strip-form base, the method comprising, before the step of depositing plating material, the step of attaching the flexible strips of fastener product to an inner cylindrical surface of a plating fixture in an arrangement wherein at least some of the fastener elements of the strips extend in the axial direction of the cylindrical surface of the plating fixture.

13. The method of claim 12 wherein the fastener elements of adjacent strips of fastener product extend in opposite directions.

14. The method of claim 3 wherein the master is in the form of multiple injection molded inserts, each insert having an array of flexible fastener elements integrally molded with and extending from a substantially rigid arcuate base, the method comprising, before the step of depositing plating material, the step of arranging the inserts about an inner cylindrical surface of a plating fixture to form a continuous master ring.

15. The method of claim 14 wherein the inserts are molded with complementing tapered sides.

16. The method of claim 3 wherein the master is in the form of a continuous molded hook ring, the array of fastener elements of the master extending radially inward from an inner surface of the hook ring.

17. The method of claim 16 wherein the molded hook ring is formed by the process of

molding a cavity transfer master against a fastener product having an array of flexible fastener elements extending therefrom;

removing the fastener product from the molded cavity transfer master, leaving an array of shaped cavities extending into the cavity transfer master corresponding to the fastener elements of the fastener product;

molding the molded hook ring in cylindrical form against the cavity transfer master, the fastener elements of the molded hook ring being formed in the shaped cavities of the cavity transfer master; and

removing the molded hook ring from the cavity transfer master.

18. The method of claim 17 wherein the cavity transfer master is molded as a flexible strip, the method including the step of wrapping and retaining the cavity transfer master about a mandrel, with its cavities facing outward, before the step of molding the molded hook ring.

19. The method of claim 17 wherein the cavity transfer master is molded as a continuous cavity ring.

20. The method of claim 17 wherein the molded hook ring is removed from the cavity transfer master by melting the cavity transfer master.

21. The method of claim 20 wherein the cavity transfer master is molded of either low-temperature castable metal or non-sulphur wax.

22. The method of claim 3 wherein the master comprises a strip of fastener product insert-molded into a rigid support sleeve in a stretched condition with its fastener elements extending radially inward and exposed for plating.

23. The method of claim 22 wherein the master is formed by the steps of

joining opposing ends of the strip of fastener product about an expandable mandrel to form a cylindrical strip of fastener product having fastener elements facing radially inward toward the mandrel;

radially expanding the mandrel to stretch the fastener product and retain the fastener product in a cylindrical form;

solidifying support material about the stretched fastener product, the support material adhering to the fastener product; and

thereafter

radially collapsing the expandable mandrel, the fastener product retained in its stretched, cylindrical form by the solidified support material.

24. The method of claim 23 further comprising trimming the width of the solidified support material to the axial width of the stretched fastener product, such that the fastener product strip of the master has two exposed circumferential edges.

25. The method of claim 24 wherein multiple masters of equal diameter are arranged concentrically to form an elongated master sleeve, the plating material being deposited simultaneously on the multiple masters to form a single, elongated mold sleeve.

26. The method of claim 3 further comprising, after the step of depositing plating material, the step of machining the inner surface of the plating material to a diameter concentric to the outer surface of the mold sleeve.

27. The method of claim 3 further comprising the step of attaching the cylindrical mold sleeve to an outer surface of a rigid cylindrical support.

28. The method of claim 27 wherein the rigid cylindrical support comprises a cooling sleeve defining passages for flowing coolant therethrough.

29. The method of claim 28 wherein the passages comprise axial grooves on the outer surface of the cooling sleeve, such that coolant flowing along the passages is in direct contact with the mold sleeve.

30. The method of claim 3 further comprising arranging multiple such mold sleeves concentrically along a mandrel to form an elongated mold roll for molding fastener product of greater width than the width of a single mold sleeve.

31. The method of claim 1 wherein the master is held in place against a surface of a rigid support fixture by applying vacuum pressure to a back surface of the master while the plating material is deposited.

32. The method of claim 1 wherein the master comprises a flexible strip of fastener product attached to a rigid support fixture.

33. The method of claim 1 wherein the deposited plating material has an overall thickness of between about 0.005 inch and 0.250 inch.

34. The method of claim 33 wherein the deposited plating material has an overall thickness of about 0.150 inch.

35. The method of claim 1 comprising depositing a layer of metal on the master before depositing the plating material.

36. The method of claim 35 wherein the metal comprises copper.

37. The method of claim 1 wherein the plating material is deposited directly on the master in an electroless plating process.

38. The method of claim 37 comprising, before the step of depositing plating material, coating the fastener elements of the master with a thin layer of colloidal catalyst particles.

39. The method of claim 1 wherein the plating material is sufficiently porous to permit cavity venting therethrough under molding pressure.

40. The method of claim 1 wherein a first layer of plating material is deposited directly on the master in an electroless plating process, and further plating material is deposited on the first layer of plating material in an electroplating process.

41. The method of claim 1 wherein the mold surface is configured to be arranged in opposition with another mold surface to form an injection mold defining a fixed cavity therein for injection molding discrete fastener products.

42. The method of claim 41 further comprising shaping the deposited plating material to form an insert having an exposed face of plating material from which the shaped cavities extend, the insert adapted to be retained within the mold with the shaped cavities contiguous with the fixed cavity of the mold.

43. The method of claim 42 wherein the exposed face of the insert comprises a curved surface for forming a portion of a curved surface of the discrete fastener products.

44. The method of claim 1 wherein the cavities are configured to mold fastener elements of less than about 0.050 inch in total height, as measured from the product base.

45. The method of claim 1 wherein each of the blind cavities includes a projection defining a volume for receiving air compressed within the cavity by advancing molten resin as a fastener element is molded therein.

46. A method of producing a multiplicity of hook fastener element-shaped blind cavities extending from a common surface of a workpiece for molding a plastic hook fastener product having a multiplicity of hook fastener elements integrally molded with and extending from a product base, the method comprising the step of depositing plating material on the common surface of the workpiece, in a predetermined pattern, to produce the multiplicity of hook fastener element-shaped blind cavities, the plating material forming a multiplicity of mold surfaces for molding corresponding surfaces of the multiple hook fastener elements.

47. The method of claim 46 wherein the cavities are configured to mold hook-shaped fastener elements.

48. The method of claim 46 wherein the cavities are configured to mold fastener elements of less than about 0.050 inch in total height, as measured from the product base.

49. The method of claim 48 wherein the cavities are constructed to mold fastener elements of less than about 0.025 inch in total height, as measured from the product base.

50. The method of claim 46 wherein the workpiece comprises at least part of a mold for molding a plastic fastener product.

51. The method of claim 50 comprising

applying a masking material to selected portions of the workpiece to produce masked regions,

depositing a layer of said plating material to the workpiece to surfaces other than the masked regions, and

removing the masking material from the masked regions to expose unplated surfaces of the workpiece.

52. The method of claim 50 wherein the workpiece comprises a flat plate, the plating material being deposited on one broad side of the plate to form mold surfaces at an edge thereof, for defining blind mold cavities extending from said edge when the plate is arranged adjacent another plate.

53. The method of claim 52 wherein the overall thickness of the plating material is between about 0.001 inch and 0.015 inch.

54. The method of claim 46 further comprising the step of machining the deposited plating material to remove an outer portion thereof to provide a flat surface for abutting an adjoining mold part.

55. The method of claim 46 wherein the plating material defines fully-formed mold cavities, each extending from an innermost portion to a base portion at an outer surface of the plating material, the plating material deposited in multiple layers defining, in order of deposition, said cavities from their innermost portions to their base portions.

56. The method of claim 55 wherein the workpiece is in the form of a flexible belt.

57. A method of forming a mold surface defining an array of blind cavities extending therefrom, each cavity having a shape of a hook fastener element, for molding a corresponding array of hook fastener elements integrally with and extending from a hook fastener product base, the method comprising the steps of

providing a master having an array of flexible hook fastener elements extending to a given height from a surface thereof;

forming a rigid mold material against the surface of the master, encasing the hook fastener elements of the master within the mold material;

solidifying the mold material; and

thereafter

removing the master from the mold material, leaving the array of blind cavities extending into the mold material from an exposed surface thereof, the array of blind cavities configured for integrally molding a corresponding array of hook fastener elements with a product base formed on said exposed surface.

58. The method of claim 57 wherein said mold material is formed by being cast as an arcuate mold section, the exposed surface of the mold material of the section forming a portion of a cylindrical surface, the method further comprising the step of arranging multiple such sections about a mandrel to form a cylindrical mold roll.

59. The method of claim 58 wherein the sections are releasably attached to the mandrel.

60. The method of claim 58 wherein the exposed surfaces of the sections abut to form a continuous cylindrical mold surface extending about the circumference of the mold roll.

61. The method of claim 57 wherein the rigid mold material comprises a thermoset polymer.

62. The method of claim 57 wherein the rigid mold material comprises a compound of bismuth, lead, tin, antimony or indium.

63. The method of claim 57, wherein the rigid mold material is formed by depositing material in a plating process.