OVERMOLDED TWO-COMPONENT FRICTION ELEMENT IN A PLASTIC PALLET

Abstract

The invention is directed to an overmolded two-component friction element in a plastic pallet and to a method for forming the pallet. The friction element includes a rigid outer carrier member and an elastomeric material that is exposed at one or more ends. The friction element is first formed in an injection mold, and then is placed in a pallet mold. Resin is injected into the pallet mold around the sides of the friction element leaving the exposed elastomeric material form part of the pallet surface.

Claims

1. A method of forming a transportation system with an over-molded friction element comprising: forming a rigid outer carrier member having a cavity of a first friction element; placing an elastomeric material into the cavity of the outer carrier member of the first friction element; placing the first friction element into a mold for a transportation system; and, molding over an outer surface of the carrier member of the first friction element in the mold for the transportation system so that a first portion of the elastomeric material of the first friction member is exposed on a surface of the transportation system.

2. The method of claim 1 wherein the steps of forming a rigid outer carrier member having a cavity of a first friction element and placing an elastomeric material into the cavity of the rigid outer carrier member of the first friction element comprise: injecting the rigid material into a first cavity of a multi-cavity injection mold to form the outer carrier member; moving the rigid outer carrier member to a second cavity of the multi-cavity injection mold; and, injecting the elastomeric material into the cavity of the rigid outer carrier member.

3. The method of claim 2 wherein the step of moving the outer carrier member to a second cavity of the multi-cavity injection mold comprises: using an end-of-arm tool to transfer the rigid outer carrier member from the first cavity of the multi-cavity injection mold to the second cavity of the multi-cavity injection mold.

4. The method of claim 2 further comprising: moving the first friction element from the multi-cavity injection mold onto a transportation system mold.

5. The method of claim 1 wherein the step of forming a rigid outer carrier member having a cavity of a first friction element comprises forming the outer surface of the rigid outer carrier member into a conical shape.

6. The method of claim 5 further comprising: forming a first recess on a top portion of the rigid outer carrier member and forming a second recess on a bottom portion of the rigid outer carrier member.

7. The method of claim 1 wherein the step of forming a rigid outer carrier member having a cavity of a first friction element comprises forming the outer surface of the rigid outer carrier into a cylindrical shape.

8. The method of claim 1 wherein the step of forming a rigid outer carrier member having a cavity of a first friction element comprises forming the outer surface of the rigid carrier member into a plurality of planar surfaces.

9. The method of claim 8 wherein the step of forming the outer surface of the rigid carrier member into a plurality of planar outer surfaces provides a rectangular cross-sectional shape of the outer carrier member.

10. The method of claim 1 wherein the step of forming a rigid outer carrier member having a cavity of a first friction element comprises forming the outer surface of the rigid outer member into an oval shape.

11. The method of claim 1 wherein the transportation system is a plastic pallet.

12. The method of claim 1 wherein the step of molding over an outer surface of the carrier member of the first friction element in the mold for the transportation system so that a first portion of the elastomeric material of the first friction member is exposed on a first surface of the transportation system comprises: loading the first friction element onto a pin in the mold for the transportation system; and, injecting a resin that forms the transportation system into the mold over portions of the first friction element.

13. The method of claim 1 wherein the step of molding over an outer surface of the carrier member of the first friction element in the mold for the transportation system so that a first portion of the elastomeric material of the first friction member is exposed on a first surface of the transportation system includes exposing a second portion of the elastomeric material on a second surface of the transportation system opposed to the first surface.

14. The method of claim 1 wherein the elastomeric material is a thermoplastic elastomer.

15. The method of claim 1 wherein the step of molding over an outer surface of the carrier member of the first friction element in the mold for the transportation system so that a first portion of the elastomeric material of the first friction member is exposed on a surface of the transportation system comprises: mechanically trapping the first friction element in the transportation system.

16. A method of forming a pallet with friction elements comprising: forming a plurality of friction elements having an outer rigid carrier member and an elastomeric material positioned in a cavity of the outer rigid carrier member; and, positioning the plurality of friction elements into a pallet mold and injecting a resin into the pallet mold.

17. The method of claim 16 wherein the step of forming a plurality of friction elements having an outer rigid carrier member and an elastomeric material positioned in a cavity of the outer rigid carrier member comprises: injecting a rigid material into a first cavity of an injection molding machine to form the outer rigid carrier member for each of the plurality of friction elements.

18. The method of claim 17 further comprising: injecting an elastomeric material into the cavity of the outer rigid carrier member.

19. The method of claim 18 further comprising: moving the outer rigid carrier member from the first cavity of the injection molding machine to a second cavity of the injection molding machine prior to the step of injecting an elastomeric material into the cavity of the outer rigid carrier member.

20. The method of claim 17 wherein the step of injecting a rigid material into a first cavity of an injection molding machine to form the outer rigid carrier member for each of the plurality of friction elements comprises: forming a recess into an outer surface of the rigid outer carrier member.

21-35. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0032] To understand the present invention, it will now be described by way of example, with reference to the accompanying drawings in which:

[0033] FIG. 1 is a top perspective view of a friction element in accordance with an aspect of the present invention;

[0034] FIG. 2 is a bottom perspective view of a friction element of FIG. 1;

[0035] FIG. 3 is a cross-sectional view of the friction element of FIG. 1;

[0036] FIG. 4 is a cut-away view of the friction element of FIG. 1;

[0037] FIG. 5 is a perspective view of a friction element of FIG. 1 being placed on a portion of a cavity side of a mold for a pallet;

[0038] FIG. 6 is a bottom perspective view of a portion of a core side mold for the pallet for placement of a friction element;

[0039] FIG. 7 is a top perspective view of a portion of a pallet formed in the mold portions of FIGS. 5 and 6 with a molded over friction element;

[0040] FIG. 8 is a bottom perspective view of the portion of a pallet of FIG. 7 formed in the mold portions of FIGS. 5 and 6 with the molded over friction element;

[0041] FIG. 9 is a perspective view of a pallet with a plurality of friction elements molded into the pallet;

[0042] FIG. 10 is a perspective view of a portion of a core side mold for a pallet for instances where a friction element is not desired;

[0043] FIG. 11 is a perspective view of a portion of a pallet without a friction element;

[0044] FIG. 12 is a top perspective view of an outer carrier member of a friction element having a first and second recessed portion in accordance with another aspect of the invention;

[0045] FIG. 13 is a bottom perspective view of the outer carrier member of FIG. 12;

[0046] FIG. 14 is a side plan view of the outer carrier member of FIG. 12;

[0047] FIG. 15 is a top plan view of the outer carrier member of FIG. 12;

[0048] FIG. 16 is a bottom plan view of the outer carrier member of FIG. 12;

[0049] FIG. 17 is a vertical cross-sectional view of the outer carrier member of FIG. 12;

[0050] FIG. 18 is a horizontal cross-sectional view of the outer carrier member of FIG. 12;

[0051] FIG. 19 is a to perspective view of a friction element formed from the outer carrier member of FIG. 12 with an elastomeric material in an interior cavity of the outer carrier member;

[0052] FIG. 20 is a bottom perspective view of the friction element of FIG. 19;

[0053] FIG. 21 is a side plan view of the friction element of FIG. 19;

[0054] FIG. 22 is a vertical cross-sectional view of the friction element of FIG. 19;

[0055] FIG. 23 is a perspective view of a friction element in accordance with another aspect of the present invention;

[0056] FIG. 24 is a perspective top view of a friction element in accordance with another aspect of the present invention;

[0057] FIG. 25 is a bottom perspective view of the friction element of FIG. 24;

[0058] FIG. 26 is perspective view of a portion of a pallet mold and the friction element of FIG. 24:

[0059] FIG. 27 is a cross-sectional view of the portion of the pallet mold and the friction element of FIG. 26;

[0060] FIG. 28 is a perspective top view of a friction element in accordance with another aspect of the present invention;

[0061] FIG. 29 is a bottom perspective view of the friction element of FIG. 28;

[0062] FIG. 30 is perspective view of a portion of a pallet mold and the friction element of FIG. 28:

[0063] FIG. 31 is a cross-sectional view of the portion of the pallet mold and the friction element of FIG. 30;

[0064] FIG. 32 is a perspective top view of a friction element in accordance with another aspect of the present invention;

[0065] FIG. 33 is a bottom perspective view of the friction element of FIG. 32;

[0066] FIG. 34 is perspective view of a portion of a pallet mold and the friction element of FIG. 32;

[0067] FIG. 35 is a cross-sectional view of the portion of the pallet mold and the friction element of FIG. 34;

[0068] FIG. 36 is a perspective top view of a friction element in accordance with another aspect of the present invention;

[0069] FIG. 37 is a bottom perspective view of the friction element of FIG. 36;

[0070] FIG. 38 is perspective view of a portion of a pallet mold and the friction element of FIG. 36;

[0071] FIG. 39 is a cross-sectional view of the portion of the pallet mold and the friction element of FIG. 38;

[0072] FIG. 40 is a perspective top view of a friction element in accordance with another aspect of the present invention;

[0073] FIG. 41 is a bottom perspective view of the friction element of FIG. 40;

[0074] FIG. 42 is perspective view of a portion of a pallet mold and the friction element of FIG. 40;

[0075] FIG. 43 is a cross-sectional view of the portion of the pallet mold and the friction element of FIG. 42;

[0076] FIG. 44 is a perspective top view of a friction element in accordance with another aspect of the present invention;

[0077] FIG. 45 is a bottom perspective view of the friction element of FIG. 44;

[0078] FIG. 46 is perspective view of a portion of a pallet mold and the friction element of FIG. 44; and,

[0079] FIG. 47 is a cross-sectional view of the portion of the pallet mold and the friction element of FIG. 46.

DETAILED DESCRIPTION

[0080] While this invention is susceptible of embodiments in many different forms, there is shown in the drawings and will herein be described in detail preferred embodiments of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to the embodiments illustrated.

[0081] The present invention is directed to a pallet (or other similar transportation system for moving products) with overmolded friction elements. The friction elements are formed in a first mold, and then placed in a mold for forming the pallet. The friction elements are then molded over in the pallet mold to form a pallet having exposed friction material on one or more surfaces.

[0082] FIGS. 1-4 show a two-component friction element 10 in accordance with an aspect of the present invention. The friction element 10 includes a rigid outer carrier member or portion 12 having a conically shaped outer surface 14. The friction element also includes an elastomeric material 16 that is shown exposed on and extending slight past the top and bottom ends of the outer carrier member. As illustrated in FIGS. 3 and 4 (and FIG. 17), the elastomeric material 16 is contained within cavities 18, 20 formed in the interior of the outer carrier member 12. The cavities 18, 20 extend between an outer wall 22 of the outer carrier member 12, and an inner wall 24 of the carrier member 12. The inner wall 24 defines a channel that extends through the friction element 10.

[0083] The friction elements 10 are preferably formed in a two shot injection molding process. The process is performed in an injection mold having two cavities (or in some instances multiples of two cavities can be used to form a plurality of friction elements at the same time) and two barrels of injectable material. In a first shot, the outer rigid carrier member 12 is formed in the first cavity with an injection of material from the first barrel. In most cases, the material used in the first barrel is the same or similar to the material used to form the pallet. The outer carrier member 12 is then moved to the second cavity of the mold (typically by an EAOT). The second shot is injection of an elastomeric material, such as a thermoplastic elastomer (TPE) that has the desired friction properties, from the second barrel into the cavities 18, 20 of the outer carrier member 12 (this occurs while a new carrier member is formed in the first cavity of the friction element mold).

[0084] The completed friction element 10 is then loaded into a pallet forming mold. As shown in FIG. 5, the pallet mold includes one or more mold portions 26 having pins or posts 28. The friction element 10 is positioned so that the pin 28 fits in the channel defined by the inner wall 24 of the friction element 10. In addition to being used during the pallet molding process, the channel defined by the inner wall 24 of the carrier member 12 of the friction element 10 allows for drainage on the finished pallet.

[0085] Preferably, the friction elements 10 are loaded on the mold portion 26 in the cavity side (i.e., stationary side) of the pallet mold. A core portion or side (i.e., moving side) 30 of the pallet mold, illustrated in FIG. 6, includes a cavity 32 that conforms to the outer shape of the friction elements 10. The pallet mold is closed and the resin that forms the pallet is injected into the mold, surrounding the outer surfaces 14 of the friction elements 10. FIGS. 7 and 8 show the top and bottom of a friction element 10, respectively, in a portion of a pallet 34. The pallet portion 34 includes a portion 36 surrounding the friction element 10 (i.e., overmolded), and a plurality of interconnecting ribs 38. The entire pallet 40 having a plurality of overmolded friction elements 10 is shown in FIG. 9. Typically, the pallet can include 20 or more friction elements 10.

[0086] In instances where a friction element is not desired at a particular location on the pallet, a modified mold portion 42, shown in FIG. 10, can be used. The mold portion 42 has an enlarged post 44 to replace the friction element. The top or core portion of the mold can be the same as that shown in FIG. 6. A portion 46 of the pallet formed from the mold portion 42 is shown in FIG. 11.

[0087] Another friction element 48 and its outer carrier member 50 are shown in FIGS. 12-20. The outer carrier member 50 includes a central outer surface portion 52 having a conical shape similar to the friction element 10 of FIGS. 1-11. However, the carrier member 50 also includes a first recessed groove 54 at the top of the carrier member 50 and a second recessed groove 56 at the bottom of the carrier member 50. The area defined by the recessed grooves 54, 56 is filled with resin when in the pallet mold (during the overmold process). This geometry creates a locking mechanism to mechanically trap the friction element 48 to the pallet portion 34 or pallet 40. Clearly, a large variety of structures (e.g. internal grooves, or ribs that extend outward) can be designed into the carrier member to lock the friction element to the pallet. This mechanical locking effectively holds the friction element 48 in place regardless of whether the pallet material thermally or chemically bonds to the material forming the outer surface of the carrier member.

[0088] As evident in FIGS. 19-22, the recessed grooves 54, 56 do not prevent the elastomeric material 58 from being exposed at the top or bottom of the friction element 48. As more clearly shown in FIGS. 21 and 22, the elastomeric material extends slightly above and below, respectively, the material of the carrier member 50.

[0089] Another version of a friction element 60 is shown in FIG. 23. The friction element 60 has an outer carrier member with a central portion having an outer surface 62 with a more cylindrical shape than the friction elements 10, 48 previously discussed. Recessed grooves 64, 66 are formed at the top and bottom of the carrier member. An elastomeric material 68 is shown on the top of the friction element 60.

[0090] FIGS. 24-27 show a friction element 70 having an internal channel that is closed at one end. The friction element 70 can be loaded on a pallet mold portion 34 through the opening at the top of the channel 72 evident in the top view of FIG. 24. The bottom view of FIG. 25 shows the bottom end including a central bottom wall 74. The friction element 70 can be formed with recessed grooves or other similar structure.

[0091] FIGS. 28-31 show a friction element 76 having a rectangular shaped top end and bottom end. The carrier member 78 of the friction element 76 has a plurality of planar outer surfaces 80. Again, recessed grooves can be formed in the friction element 76. Fewer or more planar faces can be formed for other polygonal shaped ends.

[0092] FIGS. 32-35 show a friction element 82 having oval shaped ends and corresponding oval shaped outer surface 84. In each of the above alternatively shaped elements, a post that corresponds to the channel in each element is provided in the mold portion 34.

[0093] FIGS. 36-39 show a friction element 86 having an oval shape similar to that of FIGS. 32-35. In this example, the element includes two channels 88, 90. A mold portion having two posts 92, 94 is provided for positioning the friction element 86. The friction element can also be formed with more than two channels.

[0094] FIGS. 40-43 show a friction element 96 that only has an elastomeric material 98 exposed on one side. The channel also has a closed end similar to the friction element 70.

[0095] FIGS. 44-47 show a friction element 100 that does not include any internal channels for positioning on a mold portion. Instead, posts 102 on the mold fit into grooves 104 on the sides of the element 100. This friction element 100 only has the elastomeric material 106 exposed at one end.

[0096] While the friction elements are seen being held by posts in the mold portions, other means for securing the elements can be used. For example, a vacuum in the receptacle area for the friction element in the pallet mold can be used. Alternatively, the friction element can have a protruding structure which mates with a channel or opening in the mold portion. Moreover, an adhesive can utilized.

[0097] Many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood within the scope of the appended claims the invention may be protected otherwise than as specifically described.