METHOD OF FORMING NON-PNEUMATIC TIRE USING UNCURED SHEAR BAND RING AND CURED TREAD SECTION

FIELD OF THE INVENTION

[0001] The present invention relates generally to a method of constructing a non-pneumatic tire. More particularly, the present application involves a method of constructing a non-pneumatic tire that includes the steps of placing a cured tread section onto an uncured shear band ring and then subsequently curing the assembly to create a permanent attachment between the now cured shear band ring and the cured tread section.

BACKGROUND

[0002] Non-pneumatic tires for vehicles and other applications may include an inner hub or wheel surrounded circumferentially by an outward radially disposed tread that includes an annular shear band. A support structure made up of a series of spokes can be disposed radially between the hub and tread and can function to connect these two components. As the tire rotates under load, the spokes experience bending and compression deformation when they are located downward near the contact patch of the tire. The spokes straighten outside the contact patch relieving the bending and compression deformation and may experience tension 180 degrees from the contact patch. Although described as having spokes, the support structure of a non-pneumatic tire may instead have a honeycomb like structure, a solid structure, or a variety of other configurations in different designs.

[0003] The annular shear band ring is disposed radially outward from the support structure, and the tread section of the non-pneumatic tire is in turn located radially outward from the shear band ring. The shear band ring supports the tread and functions to tie in the various spokes of the supporting structure that transfer the load of the vehicle and forces exhibited onto the tread when driving. The shear band ring and the tread may be formed by a molding process in which uncured rubber making up portions of the shear band ring and tread is cured. The mold provides the desired shape and size to the shear band ring and tread. Although capable of forming a cured and permanently attached shear band ring and tread, the molding of these components in a single press results in uniformity issues in that certain portions of the assembly will not be the same as others in various portions about the circumference of the assembly. Still further, the use of multiple presses to form the shear band ring and tread requires a significant amount of investment when producing shear band rings and tread in production quantities. As such, there remains room for variation and improvement within the art.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] 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 more particularly in the remainder of the specification, which makes reference to the appended Figs, in which:

[0005] Fig. 1 is a perspective view of a non-pneumatic tire.

[0006] Fig. 2 is a side elevation view of a flat tread press used to form a cured tread section.

[0007] Fig. 3 is a perspective view of a metal spool with an uncured shear band ring formed on an outer radial surface of the metal spool.

[0008] Fig. 4 is a cross-sectional view taken along line 4-4 of Fig. 3.

[0009] Fig. 5 is a perspective view of the metal spool and uncured shear band ring of Fig. 3 with a cured tread section positioned on the uncured shear band ring.

[0010] Fig. 6 is a cross-sectional view taken along line 6-6 of Fig. 5.

[0011] Fig. 7A is a cross-sectional view of a spool, uncured shear band ring, and cured tread section with pressure applied via a membrane.

[0012] Fig. 7B is a detailed view of the circle of 7B in Fig. 7A.

[0013] Fig. 8 is a cross-sectional view of the assembly of Fig. 7 being cured within an autoclave.

[0014] Fig. 9 is a side elevation view of a support structure that has spokes.

[0015] Fig. 10 is a side elevation view of a non-pneumatic tire that includes the support structure of Fig. 9 along with a hub, shear band ring, and tread.

[0016] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the invention. DETAILED DESCRIPTION OF REPRESENTATIVE EMBODIMENTS

[0017] 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.

[0018] It is to be understood that the ranges mentioned herein include all ranges located within the prescribed range. As such, all ranges mentioned herein include all sub-ranges included in the mentioned ranges. For instance, a range from 100-200 also includes ranges from 110-150, 170- 190, and 153-162. Further, all limits mentioned herein include all other limits included in the mentioned limits. For instance, a limit of up to 7 also includes a limit of up to 5, up to 3, and up to 4.5.

[0019] The present invention provides for a method of forming a shear band ring 12 with an attached cured tread section 22 that can be incorporated into a non-pneumatic tire 10. The method involves the construction of an uncured shear band ring 12 that may be built upon a metal spool 28 or other device. A cured tread section 22 is placed upon the uncured shear band ring 12. One or more membranes 34 may be wrapped around the assembly in order to urge the uncured tread section 22 and the cured tread section 22 against one another. The assembly may be placed into an autoclave 30 in order to apply heat and pressure. The uncured tread section 22 can be cured, and likewise the attachment between the uncured tread section 22 and the cured tread section 22 can also be cured in the autoclave 30. After curing, the shear band ring 12 and the cured tread section 22 are permanently attached to one another and both of these components are cured. Other components of the non-pneumatic tire 10 can be incorporated into this subassembly such as a supporting structure 62 and a hub 78.

[0020] With reference to Fig. 1, a non-pneumatic tire 10 is shown through which a central axis 14 extends. The central axis 14 is identified with other components of the non-pneumatic tire 10 and may be described as well as being the central axis 14 of the shear band ring 12. The central axis 14 relates to the position of the components once assembled into the non-pneumatic tire 10. The other directions identified herein, such as the axial direction 16, radial direction 18, and the circumferential direction 20, likewise relate to the position of the non-pneumatic tire 10 and its components when assembled, along with the devices used to construct the non-pneumatic tire 10 upon assembly of the non-pneumatic tire 10. An axial direction 16 is defined as the direction along the central axis 14 or the direction parallel to the central axis 14. The radial direction 18 extends at a 90 degree angle to the axial direction 16, and the circumferential direction 20 extends around the arc length of the non-pneumatic tire 10, or its components, so as to circle 360 degrees the central axis 14. The axial direction 16, the radial direction 18 and the circumferential direction 20 are identified with other components in the drawings that are then subsequently assembled into the non-pneumatic tire 10 as their orientations would be upon assembly. The non-pneumatic tire 10 includes a hub 78 that can be mounted onto a wheel of the vehicle. The central axis 14 extends through the center of the hub 78.

[0021] Located outward from the hub 78 in the radial direction 18 is a supporting structure 62. The supporting structure 62 may be designed in a variety of manners. Although shown as having an inner V pair spoke section 72, an interface ring 74, and an outer V pair spoke section 76, the supporting structure 62 may be variously designed in accordance with other exemplary embodiments.

[0022] The non-pneumatic tire 10 also has a shear band ring 12 that engages the supporting structure 62 and is located radially outward from the supporting structure 62 in the radial direction 18. Tread is also included in the non-pneumatic tire 10 on a cured tread section 22 and is attached to the shear band ring 12. The supporting structure 62 may be formed as a single component, or can be made by individually constructing two or three subcomponents and then assembling these two or three modular pieces together to form the supporting structure 62. Construction in two or three modular pieces may allow for benefits in cost and performance to be realized.

[0023] Fig. 2 shows a flat tread press 66 that can produce the tread of the non-pneumatic tire

10. A tread section 22, that can be uncured rubber, can be placed into a mold portion 84 of the flat tread press 66. An upper portion 82 can be moved toward and away from the mold portion 84 by use of one or more cylinders 80. The upper portion 82 may apply pressure to the tread section 22 to force it into the mold portion 84. Heat can be transferred into the tread section 22 from the upper portion 82 and/or the mold portion 84, and the heat along with the applied pressure may function to cure the uncured rubber of the tread section 22. A cured tread section 22 that is a longitudinal strip of cured rubber can thus be formed by the flat tread press 66. Once cured, the cylinders 80 can move the upper portion 82 away from the mold portion 84 and the cured tread section 22 can be removed from the mold portion 84. Although described as being formed by a flat tread press 66, it is to be understood that the cured tread section 22 can be formed by a variety of other types of presses or machines.

[0024] The tread section 22 may be cured in that it does not require further curing in order to vulcanize the rubber included in the tread section 22. The tread section 22 may not include a bead, and may not include any spokes of the non-pneumatic tire 10. The tread section 22 may be made of a single material or may be made from multiple materials in accordance with various exemplary embodiments. The tread section 22 that is incorporated into the non-pneumatic tire 10 may be a virgin tread section 22 in that it was not previously used, and is not part of a retread process, and in that it was never before incorporated into a tire after its formation.

[0025] Figs. 3 and 4 show a metal spool 28 with a shear band ring 12 formed thereon.

Although described as a metal spool 28, the spool 28 may be made out of other materials in other exemplary embodiments such as a composite material. The metal spool 28 may be inexpensive and may remove the need to invest in molds for the construction of the shear band ring 12 and the tread section. The spool 28 has an outer radial surface 32 that is curved along its entire circumferential length, and has an opening that extends completely through its center in the axial direction 16. The shear band ring 12 may be built upon the outer radial surface 32 and can be made of a single layer or a plurality of layers of material. The shear band ring 12 may be made of uncured rubber 68, and a composite layer 70 can be included within the uncured rubber 68. Any number of composite layers 70 can be included and may be made of the same or different materials. There may be from 1-4, from 5-9, from 10-15, or up to 20 composite layers 70 included within the shear band ring 12. The composite layers 70 can be on the outer radial exterior surface of the uncured rubber 68, embedded within the uncured rubber 68, on the radial interior surface of the uncured rubber 68, or spaced from all of or portions of the uncured rubber 68 in the axial direction 16. Although described as having one or more composite layers 70, it is to be understood that the shear band ring 12 need not include any composite layers 70 in accordance with other exemplary embodiments.

[0026] The metal spool 28 also features a pair of flanges 90 and 92 located on either end in the axial direction 16. The flanges 90, 92 extend outward in the radial direction 18 from the outer radial surface 26. The shear band ring 12 and the cushion gum 24 are built between the flange 90,

92 and in some instances may engage the inner surfaces of the flanges 90, 92. The shear band ring 12 and cushion gum 24 could extend upwards beyond the upper surfaces of the flanges 90, 92 in the radial direction 18, or the flanges 90, 92 may be higher than the shear band ring 12 and cushion gum 24 in the radial direction 18. Flange 90 features a groove 94 that can extend all the way around the flange in the circumferential direction 20. The groove 94 extends some distance inward in the radial direction 18 from the surface of the flange 90. Flange 92 can be arranged in a similar manner with groove 96 defined thereon.

[0027] The shear band ring 12 is thus made up of uncured rubber 68, which is rubber that is not vulcanized. The entire shear band ring 12 may be uncured, or only components of the shear band ring 12 may be uncured. The uncured rubber 68 may be applied in a single layer or multiple layers as desired. Further, the composition of materials making up the one or more layers of the uncured rubber 68 may be the same as one another or different from one another, layer to layer, in accordance with various exemplary embodiments. When assembled onto the metal spool 28, the shear band ring 12 includes at least one component that is uncured. The shear band ring 12 may be referred to as a green shear band and can be placed into form before assembly with the cured tread section 22. Further, although disclosed as being assembled onto an outer radial surface 32 of a metal spool 28, it is to be understood that the shear band ring 12 that has the at least one uncured component may be assembled onto any other type of base in accordance with other exemplary embodiments.

[0028] Figs. 5 and 6 show the next step in the process in which the cured tread section 22 is assembled onto the shear band ring 12. In order to affect this assembly, cushion gum 24 can be located between the shear band ring 12 and the cured tread section 22. The cushion gum 24 can be applied to the outer radial surface 26 of the shear band ring 12 around the entire circumference of the outer radial surface 26. Alternatively, the cushion gum 24 can be applied to the inner radial surface of the cured tread section 22, or the cushion gum 24 may be applied to both the inner radial surface of the cured tread section 22 and to the outer radial surface 26. The cushion gum 24 is an uncured component of the assembly. In other various embodiments, the cushion gum 24 is not even present in the assembly of the shear band ring 12 to the cured tread section 22. As such, it is to be understood that other exemplary embodiments exist in which the cushion gum 24 is not present in the construction of the non-pneumatic tire 10.

[0029] The cured tread section 22 can then be applied to the cushion gum 24 on the outer radial surface 26. The cured tread section 22 may be positioned along the entire circumferential length of the outer radial surface 26 so as to extend 360 degrees around the outer radial surface 26. The cushion gum 24 has a sufficient degree of tackiness to cause the cured tread section 22 to be held onto the outer radial surface 26. In the axial direction 16, the cured tread section 22 can extend along the entire axial length of the shear band ring 12 so as to cover the entire outer radial surface 26. Alternatively, the axial length of the cured tread section 22 may be longer than that of the shear band ring 12 in the axial direction 16 so that it overlaps some or all of the side portions of the shear band ring 12. In yet other arrangements, the axial length of the cured tread section 22 is less than the length of the shear band ring 12 in the axial direction 16 so that portions of the outer radial surface 26 are not covered by the cured tread section 22 and are visible. The cured tread section 22 may be a single section along its entire length in the axial direction 16, or may be made of multiple pieces of tread that are strips that are arranged next to one another in the axial direction 16 on the shear band ring 12. The use of multiple strips of tread to make up the cured tread section 22 may allow for flexibility in fabricating dimensions of various widths when using the same mold. The cured tread section 22 may be located outward from the flanges 90, 92 in the radial direction 18, and the cured tread section 22 may be located between the flanges 90, 92 in the axial direction 16.

[0030] The next step in the assembly may be the application of a membrane 34 to the assembled shear band ring 12 and cured tread section 22. Fig. 7 shows a membrane 34 that is a flexible member that is wrapped around the shear band ring 12 and the cured tread section 22. The membrane 34 engages the cured tread section 22, and in some instances may engage the shear band ring 12 as well. The membrane 34 engages the flanges 90 and 92. The membrane 34 can be a single component, or multiple membranes 34 can be present as desired. In some embodiments, the membrane 34 may wrap around the flanges 90 and 92 so as to engage portions of the inner surface of the metal spool 28 and may be located within the metal spool 28. In the embodiment illustrated, the membrane 34 is located within the grooves 94 and 96. A gasket 98 is located within the groove 94 and functions to hold the membrane 34 within the groove 94 as the gasket 98 is pressed within the groove 94 in a frictional fit engagement. In a similar manner, a gasket 100 is located within the groove 96 in a friction fit arrangement in order to hold the membrane 34 within the groove 96. To further aid in retention of the membrane 34, a strap 102, which may be an adjustable metal strap, is located over the gasket 98 and may be tightened and applied to this connection area in order to securely retain the membrane 34 along with the gasket 98 to the flange 90. Strap 104, which may likewise be an adjustable metal strap 104, is located over the gasket 100 and functions to secure the gasket 100 and membrane 34 to the flange 92. Although not specifically shown in the drawings, the straps 102, 104 could extend in the axial direction 16 along almost all of the axial lengths of the flanges 90, 92.

[0031] A source of vacuum is connected to the membrane 34 and is applied to cause the membrane 34 to collapse upon itself and move inward in the radial direction 18 and upon

components contained within the membrane 34. The membrane 34 thus applies a force 86 to the assembled cured tread section 22 to press the cured tread section 22 down onto the cushion gum 24 against the shear band ring 12. The outer radial surface 32 is not a flexible component and thus does not flex when the force 86 is applied. However, the shear band ring 12 and the cured tread section 22, along with the cushion gum 24, will flex somewhat during application of force 86 as they do exhibit some ability to flex. The force 86 will cause the cured tread section 22 and the shear band ring 12 to be drawn against the outer radial surface 32 and held thereon in somewhat of a

compressed state.

[0032] Although described as using a membrane 34 to apply pressure to the shear band ring 12 and the interface connection between the shear band ring 12 and the cured tread section 22, other types of components or assemblies may be employed to cause force 86 to be exerted. A band that applies pressure or a series of cylinders can be used to apply the force 86. As such, any type of mechanism may be used to compress the uncured portions of the assembly and press the connection between the shear band ring 12 and the cured tread section 22 together.

[0033] The next step in the process may be placement of the shear band ring 12, cured tread section 22, metal spool 28, and membrane 34 within an autoclave 30 as shown for example in Fig. 8. In the autoclave 30, heat and pressure are applied to the assembly in order to cure the uncured shear band ring 12 and the cushion gum 24 in order to permanently attach the shear band ring 12 to the cured tread section 22. If the shear band ring 12 is made of a combination of cured and uncured components, the uncured components may be cured when the assembly is in the autoclave 30. The autoclave 30 may produce force 88 which is applied to the cured tread section 22 and the shear band ring 12 in order to further effect curing and attachment of these two sections. The force 88 may also act on the membrane 34 and onto the metal spool 28 and can function to compress the flexible components of the assembly in the same manner as previously discussed with respect to the force 86. [0034] During the curing process, the force 86 applied by the membrane 34 may continue to be applied along with the force 88 applied by the autoclave 30 in order to press the connection of the shear band ring 12 and the cured tread section 22 together and to compress the shear band ring 12 in order to effect curing. The curing process can be varied so that instead of a vacuum being applied to the membrane 34 to cause compression, a positive pressure could be applied to the membrane 34 to counteract the force 88 applied by the autoclave 30 or to just remove the force 86. As such, it is to be understood that the curing process may employ force 86 and/or force 88, and in some instances neither of the forces 86 and 88 are used at certain portions of the curing process.

[0035] The curing step may involve the application of heat and pressure in any amounts for any amount of time in order to cure any uncured portions of the shear band ring 12, and to cure the cushion gum 24 to effect permanent attachment of the shear band ring 12 to the cured tread section 22. One or more thermocouples may be embedded into the uncured rubber 68 or any other portion of the shear band ring 12 or cured tread section 22 in order to measure temperature of these components being cured. The thermocouples need not be used when the non-pneumatic tire 10 is assembled in the manufacturing process, but could be used when setting up or otherwise testing the assembly in order to glean information on the heat transfer properties of the components. In accordance with one exemplary embodiment, the shear band ring 12 and cured tread section 22 are cured under vacuum to the membrane 34 in the autoclave 30 that is both heated and itself pressurized to produce the force 88. The pressure in the autoclave 30 may be 6 bars of pressure and the temperature may be 128 degrees Celsius, and the time of curing may be 1 hour after the lowest internal temperature reaches 106 degrees Celsius.

[0036] In production, multiple metal spools 28 with membranes 34, shear band rings 12, and cured tread sections 22 can be simultaneously introduced into the autoclave 30 for curing. A monorail system may be used to introduce the assemblies into the autoclave 30, and to remove them from the autoclave 30. Once curing is completed, the assembly may be removed from the autoclave 30 and the vacuum exerted onto the membrane 34 can be relieved to remove force 86. The membrane 34 may be removed from the assembly, and the attached shear band ring 12 and cured tread section 22 may be removed from the metal spool 28. The combined shear band ring 12 and cured tread section 22 are not portions of a retread process but are components of an original, unused and un-retreaded non-pneumatic tire 10. Fig. 9 shows a supporting structure 62 that can be provided for inclusion into the non-pneumatic tire 10 that has an inner V pair spoke section 72 and an outer V pair spoke section 76 that are separated from one another by an interface ring 74. A ring of material may be adjacent the outer V pair spoke section 76 and can be disposed therefrom radially outward in the radial section 18.

[0037] Fig. 10 shows the attached shear band ring 12 and cured tread section 22 assembled into the supporting structure 62 of Fig. 9. The assembly of the shear band ring 12 and the cured tread section 22 is produced after curing in the autoclave 30. The shear band ring 12 may be attached to the supporting structure 62 in a variety of manners. For example, cushion gum may be applied to the supporting structure 62 and/or the inner radial surface of the shear band ring 12 and subsequently cured in order to effect attachment. Chemical adhesives or mechanical fasteners may additionally or alternatively be used to effect attachment between the supporting structure 62 and the shear band ring 12. A hub 78 can be attached to the support structure 62 at the inner radial portion of the supporting structure 62 in order to complete or substantially complete the assembly of the non-pneumatic tire 10. The non-pneumatic tire 10 constructed in the assembly process described herein is a first run tire and is not a retread tire. As such, the cured tread section 22 is not used in a retread process, but is instead used in the manufacture of a tire 10 that is not a retread tire but is instead a first run tire. The use of a separately cured tread section 22 apart from the shear band ring 12 and subsequent assembly may increase uniformity in the resulting product. Further, the combination of a flat tread press 66 and several autoclaves 30 may be less expensive than the use of individual presses for the formation of the shear band ring 12 and tread section when mass production is desired.

[0038] The shear band ring 12 that is attached to the cured tread section 22 may be the complete shear band ring 12 of the assembly. Alternatively, the shear band ring 12 attached to the cured tread section 22 may be only a part of the assembly so that another section of the shear band ring 12 needs to be subsequently attached to the portion that is first attached to the cured tread section 22.

[0039] The present method allows for the production of a non-pneumatic tire 10 in which the shear band ring 12 is first assembled with a cured tread section 22 and then this assembly is subsequently cured and permanently attached. This method reduces or eliminates non-uniformity within these components of the non-pneumatic tire 10. Additionally, the use of a single flat tread press 66 to form the cured tread section 22, in addition to the use of a certain amount of autoclaves 30 for curing, is a more economical solution with better results than the use of a plurality of presses for the formation of the shear and ring 12 and cured tread section 22 in a single step.

[0040] While the present invention has been described in connection with certain preferred embodiments, it is to be understood that the subject matter encompassed by way of the present invention is not to be limited to those specific embodiments. On the contrary, it is intended for the subject matter of the invention to include all alternatives, modifications and equivalents as can be included within the spirit and scope of the following claims.