NON-PNEUMATIC TIRE

FIELD OF THE INVENTION

[0001] The subject matter of the present invention relates to a mold for use in manufacturing a spoke used in the construction of a non-pneumatic tire. More particularly, the present application involves a mold that has a demolding feature that functions to disengage the spoke from one or both of the mold pieces during opening of the mold.

BACKGROUND OF THE INVENTION

[0002] Non-pneumatic tires are those that do not require air or other fluid for their inflation for use. Some non-pneumatic tires have a plurality of spokes arranged circumferentially around and attached to a hub. On their opposite end, the spokes are attached to a shear band. To build the spoke component of the non-pneumatic tire, it is known to combine together the spoke component products into a long form that is cut to the desired length. This cutting can be before or after curing of the product. Another known method of producing spokes involves placing the components of the spoke into a mold that features segments that engage the spoke on the top, bottom, left and right hand sides. The segments of the mold are fastened, bolted, screwed, or otherwise secured into one another to form a closed compartment that engages the spoke and applies pressure thereon. Although capable of forming spokes for non-pneumatic tires, such a mold requires the segments be unscrewed to open the mold and remove the cured spoke which is both time consuming and expensive. Also, the molded spoke may become stuck on one of the mold pieces after the mold is opened. Additional labor and time becomes necessary to pull the molded spoke off of the mold piece upon which it is stuck. Reaching into a press to presents a safety issue, and reaching upwards to try to pry a spoke from the top of the mold may present an ergonomic issue to the operator. Still further, manually demolding the spoke from the mold piece may potentially damage the spoke if the operator uses improper technique. As such, there remains room for variation and improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: [0004] Fig. 1 is a side view of a non-pneumatic tire.

[0005] Fig. 2 is a perspective view of a spoke of a non-pneumatic tire in one embodiment.

[0006] Fig. 3 is a perspective view of a mold for molding a spoke of a non pneumatic tire that shows inner features of a first mold piece.

[0007] Fig. 4 is a perspective view of the mold of Fig. 3 rotated 180 degrees to view inner features of the second mold piece.

[0008] Fig. 5 is a cross-sectional view of the mold of Fig. 3 in the closed position with a spoke located therein.

[0009] Fig. 6 is a side view of the mold of Fig. 3 opened with the spoke being urged away from engagement surfaces.

[0010] Fig. 7 is a perspective view of the mold of Fig. 3 that utilizes a lock rod and lock element to maintain the mold in a closed position for subsequent heating in an oven.

[0011] Fig. 8 is a perspective view of a mold for molding a spoke of a non pneumatic tire that shows inner features of a first mold piece in accordance with another exemplary embodiment.

[0012] Fig. 9 is a perspective view of the mold of Fig. 8 rotated 180 degrees to view inner features of the second mold piece.

[0013] Fig. 10 is a cross-sectional view taken along line 10-10 of Fig. 9.

[0014] Fig. 11 is a cross-sectional view of the mold of Fig. 8 in the closed position with a spoke located therein.

[0015] Fig. 12 is a side view of the mold of Fig. 8 opened with the spoke being urged away from engagement surfaces.

[0016] Fig. 13 is a cross-sectional view of a portion of the mold that illustrates a configuration for utilizing the flashing to demold.

[0017] Fig. 14 is a perspective view of a mold that includes an array of first and second mold pieces for forming a plurality of spokes.

[0018] The use of identical or similar reference numerals in different figures denotes identical or similar features.

DETAILED DESCRIPTION OF THE INVENTION

[0019] Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, and not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a third embodiment. It is intended that the present invention include these and other modifications and variations.

[0020] The present invention provides for a mold 10 for forming a spoke 12 of a non-pneumatic tire 14 that features a demolding feature within the mold 10 for easier removal of the spoke 12. The demolding feature includes first and second flashing voids 28, 32 into which flashing 30 of the spoke 12 enters upon being molded. The flashing voids 28, 32 are placed into the first and/or second mold pieces 16, 20 such that when the mold pieces 16, 20 are moved away from one another during opening of the mold 10 the flashing 30 within functions to help apply shear or double shear to the spoke 12 by providing additional volume or surface to the rubber to assist in demold. This shear or double shear force acts to pull the spoke 12 from one or both engagement surfaces 18, 22 of the mold pieces 16, 20 so that the spoke 12 does not remain stuck onto the engagement surfaces 18, 22. It is to be understood that other forces are at work that function to apply demolding force in addition to the configuration of the rubber formed via the flashing voids 28, 32.

[0021] Fig. 1 shows a non-pneumatic tire 14. The non-pneumatic tire 14 has an axis 52 at its center, and the radial direction extends from the axis 52. Tread is located on the outer exterior of a shear band 54 and extends all the way around the non-pneumatic tire 14 in the circumferential direction. The shear band 54 is located inward in the radial direction from the tread and likewise extends 360 degrees around the axis 52 in the circumferential direction. A series of spokes 12 engage the shear band 54 and extend inward in the radial direction from the shear band 54 to a hub 56 of the non-pneumatic tire 14. Any number of spokes 12 can be present, and their cross-sectional shape can be different from that shown. In some instances, between 64-80 spokes 12 are present in the non-pneumatic tire 14. The hub 56 is located inward from the spokes 12 in the radial direction and can be mounted onto a wheel of the vehicle. The spokes 12 at the top of the non-pneumatic tire 14 are in tension, and the spokes 12 at the bottom are in compression as the non-pneumatic tire 14 rests on the ground and as the non-pneumatic tire 14 turns in normal operation of the vehicle.

[0022] The spoke 12 is shown in perspective view in Fig. 2 and includes a pair of legs that have triangular shaped ends. The central body of the spoke 12 is also made with a triangular shaped cross-section. The spoke 12 can be molded out of a single material, or may be made from a plurality of materials in some embodiments. Multiple layers of material can be placed onto one another and then positioned into the mold 10 for curing. It is to be understood that the shape and size of the spoke 12 formed by the mold 10 can be varied in accordance with different exemplary embodiments, and that a variety of spoke 12 configurations are possible. Materials making up the spoke 12 may include rubber, urethane, and/or polyurethane in accordance with different exemplary embodiments. The spoke 12 extends from a first end 40 to a second end 42 and may have an extension from end 40 to end 42 greater than, less than, or the same as the height of the spoke 12.

[0023] Fig. 3 shows the mold 10 in an open position and includes a first mold piece 16 and a second mold piece 20 that are complimentary to one another and designed for relative movement towards and away from one another. The first mold piece 16 has a first engagement surface 18 that is sized and shaped for receipt of a green spoke 12. It is to be understood that an uncured spoke is often referred to as a“green” spoke. The green spoke 12 engages the first engagement surface 18 during curing of the spoke 12 and may become stuck thereon upon being cured in the mold 10. A first end piece 24 is present and is located on one end of the first mold piece 16. The first end piece 24 and the first mold piece 16 can be separate components that are rigidly attached to one another so that they do not move relative to one another. The first end piece 24 and the first mold piece 16 can be attached to one another through the use of mechanical fasteners or via welding. In other arrangements, the first end piece 24 and the first mold piece 16 are integrally formed with one another.

[0024] A first flashing void 28 is present within the first end piece 24 and extends along the height of the spoke 12 and assumes an outline consistent with that of the outline of the spoke 12 at this location. The first flashing void 28 extends from the surface of the first end piece 24 into some depth of the first end piece 24, and can have a semi-circular cross- sectional shape. In other embodiments, the cross-sectional shape is triangular. In still other arrangements, any cross-sectional shape could be employed. The first mold piece 16 has a first flashing groove 44 that extends from the first flashing void 28 and runs along the depth of the spoke 12. On an opposite side of the spoke 12, the first mold piece 16 has a second flashing groove 48 that likewise extends from the first flashing void 28 and runs along the depth of the spoke 12. The first and second flashing grooves 44 and 48 are also defined in the second mold piece 20 and may have circular cross-sectional shapes and can be arranged in a completely linear manner. The first mold piece 16 has a second flat surface 38 on an end opposite that of the first end piece 24. The second flat surface 38 faces away from the middle of the first mold piece 16 and is located inboard and adjacent to a recess section of the first mold piece 16. The second mold piece 20 is shown as having a second end piece 26 that is complimentary to this recess section of the first mold piece 16 such that it is receivable therein when the mold 10 is moved into the closed position.

[0025] With reference now to Fig. 4, the mold 10 is open and rotated from the position shown in Fig. 3 so that additional features of the mold 10 can be viewed. The second mold piece 20 has a second engagement surface 22 that engages the spoke 12 during curing and has a shape complimentary to that of the first engagement surface 18 so that the desired size and shape of the spoke 12 can be realized. A second end piece 26 is located on one end of the second mold piece 20. The second end piece 26 can be removably attachable to the second mold piece 20, or these pieces 20 and 26 can be permanently attached to one another. The second end piece 26 may be rigidly attached to the second mold piece 20 so that they do not move relative to one another during curing. In some instances, the second mold piece 20 may be permanently attached to the second end piece 26, and in some embodiments the second mold piece 20 is integrally formed with the second end piece 26.

[0026] A second flashing void 32 is on the surface of the second end piece 26 and extends some amount into the second end piece 26. The second flashing void 32 has a semi circular cross-sectional shape, but can be variously shaped in accordance with other embodiments. The second flashing void 32 traces an outline along that of the end of the spoke 12 that is molded. The second flashing void 32 extends continuously from the first flashing groove 44 to the second flashing groove 48. The first and second flashing grooves 44 and 48 are shaped and sized the same as that in the first mold piece 16 and are formed when the mold pieces 16, 20 are brought together in the closed position. In other embodiments, the first and second flashing grooves 44, 48 can be formed by only one of the mold pieces 16 or 20 and not the other. The first and second flashing grooves 44, 48 could be linear in extension and straight across, or may be linear in extension but angled up or down upon extension from the first flashing void 28 to the second flashing void 32. The end of the second mold piece 20 opposite that of the end that has the second end piece 26 has a recess and a first flat surface 36 that directly faces and partially defines the recess. The first end piece 24 is receivable within this recess and the first flat surface 36 will directly face the first flashing void 28 when the first end piece 24 is received.

[0027] In use of the mold 10, the green spoke 12 is placed onto one of the first or second engagement surfaces 18, 22 and the first and second mold pieces 16, 20 are moved towards one another into the closed position. Fig. 5 is a cross-sectional view of the mold 10 of Fig. 3 in the closed position with the spoke 12 located within the mold 10. The spoke 12 engages both of the engagement surfaces 18 and 22. During the molding process, flashing 30 will be generated and will flow into the first flashing void 28 and the second flashing void 32, and may completely fill the voids 28, 32 in some embodiments. Also during the molding process, first groove flashing 46 will flow into the first flashing groove 44, and second groove flashing 50 will flow into the second flashing groove 48. As such, the two grooves 48 and 50, and the two voids 28 and 32 are all in fluid communication with the space created by the engagement surfaces 18, 22 that mold the spoke 12 in the closed position. The voids and grooves 28, 32, 48, 50 can all be in fluid communication with one another so that flashing 30, 46, 50 completely circles the spoke 12. However, in other embodiments some breaks may be present so that flashing does not completely circle the spoke 12. In the closed position, the first flat surface 36 directly faces the first flashing void 28, and the second flat surface 38 directly faces the second flashing void 32.

[0028] The spoke 12 will have pressure and heat applied for an amount and time sufficient to cure the green spoke 12 and produce a cured spoke 12. The mold 10 can then be opened so that the first and second mold pieces 16, 20 are moved away from one another, and such a mold 10 opening is shown with reference to Fig. 6. The flashing 30 within the first flashing void 28 holds the first end 40 of the spoke 12 at the first end piece 24. In a similar manner, the flashing 30 in the second flashing void 32 holds the second end 42 of the spoke 12 at the second end piece 26. The flat surfaces 36 and 38 allow the surfaces of the end pieces 24, 26 that define the first and second flashing voids 28, 32 to slide off when the mold 10 is opened. The spoke 12 experiences single shear as its opposite ends 40, 42 are urged in opposite directions from one another when the mold 10 is opened. The second end 42 is urged by force 56 in one direction, while first end 40 is urged by force 58 in an opposite direction. These forces will cause the spoke 12 to be lifted from the engagement surfaces 18, 22, either off of the entire engagement surfaces 18, 22 or a majority of the length of both of the engagement surfaces 18, 22 or off of at least a portion of one of the engagement surfaces 18 or 22. Any degree of disengagement of the spoke 12 from one or both of the engagement surfaces 18, 22 may prevent the spoke 12 from sticking to one of the engagement surfaces 18, 22 so that the spoke 12 can be more easily removed from the mold 10. In this regard, the spoke 12 may not have to be roughly pulled or pried from the engagement surface 18 or 22 to remove it from the mold 10. Continued relative movement of the first and second mold pieces 16, 20 may cause the first and/or second end 40, 42 to be pulled from the first and second end pieces 24, 26 as the flashing 30 is likewise pulled out of the first and/or second flashing voids 28, 32. The first and second groove flashing 46, 50 does not contribute to the demolding feature as the relative movement of the first and second mold pieces 16, 20 simply opens up the first and second flashing grooves 44, 48 and there is no pulling of this flashing 46, 50 via the opening.

[0029] The first flashing void 28 and the second flashing void 32 are positioned along the edges of the spoke 12 so that they are right above or right below the spoke 12. Clearance is provided from the internal cavity formed by the first and second engagement surfaces 18, 22 into which the spoke 12 is positioned so that rubber of the spoke 12 can flow into the adjacent flashing voids 28, 32. As such, when the spoke 12 is molded flashing 30 is formed in the shape of the flashing voids 28, 32 along with a thin piece of rubber connecting the spoke 12 to this flashing 30. It is possible to place the first and second flashing voids 28, 32 not just above or below the spoke 12, but at the same level as the spoke. However, this may not be the most preferred arrangement because the flashing 30 that would be formed at this location would be thickly attached to the spoke 12 and would be difficult to remove via trimming.

[0030] The mold 10 can include other features to effect molding of the spoke 12. Fig. 7 shows one of several different possible arrangements in which the mold 10 has lock down features that allow the mold 10 to be closed without the need to have a press apply a force thereon during heating of the spoke 12 in the mold 10. The arrangement shown in Fig. 17 can be that as shown and described in PCT application US2017/68670 filed December 28, 2017 titled“Mold for Manufacturing a Spoke for a Non-pneumatic Tire”, the contents of which are incorporated by reference herein in their entirety for all purposes. The portion of the mold 10 that rigidly holds the second mold piece 20 has a series of spring loaded lock rods 60 that each have a lock element depression 62. When the second mold piece 20 is moved into engagement with the first mold piece 16 to close the mold 10, the lock rods 60 move into the illustrated openings. A lock element 64 is present and is actuated by the two lock element actuators 66 and 68 in a linear direction. Actuation of the lock element 64 causes it to be placed into the lock element depressions 62 to capture the lock rods 60 and hold the first and second mold pieces 16, 20 in the closed configuration. The closed mold 10 with the spoke 12 therein can then be transported into an oven and heated to cure the spoke 12 without the need for a press to apply a constant force to the mold 10 due to the fact that the lock rods 60 are locked to the lock element 64 to mechanically apply closing force to the mold 10. To open the mold pieces 16, 20, the other one of the lock element actuators 66 or 68 is actuated to move the lock element 64 in the opposite direction to move it out of the lock element depressions 62 to release the lock rods 60 so that the mechanical closing force on the mold pieces 16, 20 is released. Although described as using the locking arrangement of Fig. 7, it is to be understood that a press or other closing arrangement can be provided with the mold 10 to effect opening and closing and eventual curing of the spoke 12 in other embodiments. As such, other embodiments are possible in which the locking arrangement is not used, but instead the mold 10 is closed through the use of a platen press and heat and pressure is applied while the platen press applies the hold down force.

[0031] Another embodiment of the mold 10 is shown in Figs. 8-12. The mold 10 in this embodiment includes a first mold piece 16 and a second mold piece 20 with substantially the same features as previously discussed with respect to previous embodiments. However, the major difference in this embodiment resides in the mold pieces 16, 20 being arranged to effect a double shear demolding force as opposed to the previously described single shear demolding force in prior embodiments. The first mold piece 16 is arranged as previously described with the exception that the first end piece 24 is not present, and in its place a recess is present that is partially defined by a first flat surface 36. The second mold piece 20 includes both the first end piece 24 and the second end piece 26. The end pieces 24, 26 define the first and second flashing voids 28 and 32. The first and second flashing voids 28, 32 are in fluid communication with the first and second flashing grooves 44, 48. When the spoke 12 is placed into the mold 10 and closed between the first and second mold pieces 16, 20, flashing 30, first groove flashing 46, and second groove flashing 50 is transferred into the voids 28, 32 and grooves 44, 48.

[0032] Fig. 12 shows the mold 10 in an open configuration where the first mold piece 16 is moved away from the second mold piece 20. The spoke 12 includes flashing 30 located at its first end 40 and second end 42 that are on opposite ends of the spoke 12. Movement of the first mold piece 16 causes the first and second flashing voids 28, 32 with disposed flashing 30 to be moved away from the second mold piece 20 so that the spoke 12 is subjected to double shear. The spoke 12 is shown as sticking to the first engagement surface 18 so that forces 56, 58 directed away from the first engagement surface 18 at some point causes the spoke 12 to be disengaged therefrom. Arrow 70 represents a sticking force of the spoke 12 to the first engagement surface 18 that may exists in the middle portion of the spoke 12 when the ends 40, 42 are pulled. The spoke 12 is shown as assuming the bent configuration from the first end 40 to the second end 42, and it may be understood that as soon as the disengagement happens, which can be immediately after the moment captured in Fig. 12, the spoke 12 may spring back to a linear shape from end 40 to end 42 and not have the illustrated curvature. The flashing 30 and flashing void 28, 32 decoupling feature can completely remove the spoke 12 from the first engagement surface 18. The temporary bending of the spoke 12, as illustrated in Fig. 12, causes some disengagement of the spoke 12 from the second engagement surface 22. Even if the spoke 12 springs back to its linear configuration, the temporary disengagement may function to weaken the attachment of the spoke 12 to the second engagement surface 22 making it easier to demold. The double shear arrangement thus weakens the attachment of the spoke 12 to the first and second engagement surfaces 18, 22 after molding making it easier to remove the spoke 12 from the mold 10.

[0033] The first and second flashing grooves 44, 48 are arranged in the same manner as previously discussed and do not contribute to any application of forces to the demolding of the spoke 12. When the pieces 16, 20 separate the cavities on each one of the mold pieces 16, 20 open without capturing or otherwise pulling the first groove flashing 46 and second groove flashing 50. However, other arrangements of the first and second flashing grooves 44, 48 could be used to aid in the demolding by being configured in a manner similar to that of the first and second flashing voids 28, 32 that use the flashing 30 for the demolding force. In some instances, the first flashing groove 44 is located completely within the first mold piece 16 or second mold piece 20, and the second flashing groove 48 is located completely within the other one of the first mold piece 16 or second mold piece 20.

[0034] Fig. 13 is a cross-sectional view of a portion of the mold 10 with the spoke 12 therein being cured that illustrates the arrangement between the flashing 30 and the spoke 12. A clearance is present at the intersection of the first flat surface 36 and the first end piece 24 such that a path exists between the spoke 12 being molded and the first flashing void 28. This path allows rubber of the spoke 12 to flow into the first flashing void 28 and fill it as the flashing 30. When the second mold piece 20 is moved away, the presence of the flashing 30 in the first flashing void 28 relative to the position of the rest of the spoke 12 causes the spoke to be retained somewhat to the first end piece 24 to assist in the demolding of the spoke 12. The path from the spoke 12 to the first flashing void 28 can be longer in other arrangements. Additionally, the path can be very short so that the first flashing void 28 is right at the cavity into which the spoke 12 is molded. Once the spoke 12 is removed, this flashing 30 can be trimmed by cutting the thin piece that is present in the path portion of the design. In other arrangements, the flashing 30 could be next to the spoke 12 without the presence of this path, but such a design is not preferred because it would be tougher to trim this flashing 30 as compared to flashing 30 that includes the thin path piece. The first mold piece 16 can engage the second mold piece 20 when the mold 10 is closed, or these two pieces 16, 20 may not engage one another when the mold 10 is closed. In yet other configurations, some portions of the first mold piece 16 engage some portions of the second mold piece 20 when the mold 10 is closed, while other portions of the first mold piece 16 and second mold piece 20 do not touch when the mold 10 is closed.

[0035] The mold 10 can be configured in such a manner that four parts are present and can be permanently assembled. In this regard, the first end piece 24 can be permanently attached to the first mold piece 16, and the second end piece 26 can be permanently assembled to the second mold piece 20. These components may form two rigid bodies that move relative to one another, but do not move relative themselves such that the first end piece 24 is rigidly attached and non-movable to the first mold piece 16, and the second end piece 26 is non-movable and rigidly attached to the second mold piece 20. Some or all of the excess flashing 30 can be used in the demolding process to help extract the spoke 12. If a platen is used to open the mold 10, the force of the platen opening the mold 10 can be transferred to the spoke 12 to shear the cured spoke 12 out of the cavity to eliminate or reduce the need or amount of manual disassembly of the spoke 12. The mold 10 is arranged so that only one direction of relative movement, for instances the up/down direction, between the pieces 16, 20 is needed to open and close the mold 10. This arrangement may eliminate any longitudinal or lateral movement of one or mold 10 pieces to effect opening and closing of the mold 10.

[0036] Continued use of the mold 10 results in the sides of the mold 10 associated with the first flashing void 28 and the second flashing void 32 getting“dirty” at the same rate. This even wear of the mold 10 may cause the shear forces to be balanced on each side to achieve longevity of the mold 10. The mold 10 can be arranged so that it does not have ejectors or springs that are used to remove the spoke 12 from the engagement surfaces 18 or 22. Some of the flashing produced in the molding process can be used to facilitate the demolding feature, while other amounts of the flashing produced in the molding process do not assist in demolding.

[0037] The mold 10 can be provided for molding a single spoke 12 or could be configured into an array so that multiple spokes 12 can be cured with a single platen or could be molded at the same time. Fig. 14 shows one such array in which the mold 10 has first and second pieces 16, 20 that feature engagement surfaces 18, 22 that form a plurality of spokes 12 in the molding process. A number of end pieces 24, 26 are present into which the first and second flashing voids 28, 32 can be disposed to effect the demolding feature described herein. The array utilizes the single shear arrangement as previously discussed, but in other embodiments could be configured to function with the double shear set up, or be configured to operate with some spokes 12 demolded via single shear and other spokes 12 demolded via double shear.

[0038] While the present subject matter has been described in detail with respect to specific embodiments and methods thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, the scope of the present disclosure is by way of example rather than by way of limitation, and the subject disclosure does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be apparent.