Non-pneumatic tire having metal spokes formed by a controlled thermal processing process

Abstract

A method for manufacturing spokes for a non-pneumatic tire includes providing a steel plate, heating the steel plate to a temperature of at least 1000°C, and rolling the steel plate at a temperature of at least 900°C until the thickness of the steel plate is reduced by at least 80%. The method also includes performing a first quench of the steel plate and reheating the steel plate. The method further includes rolling the steel plate until the thickness of the steel plate is further reduced by at least 80%, air cooling the steel plate, and reheating the steel plate. The method also includes performing a second quench of the steel plate and tempering the steel plate. The method further includes cutting the steel plate into a plurality of steel strips and forming the steel strips into a plurality of steel spokes.

Description

[Technical Field]

[0001] The present disclosure relates to non-pneumatic tires. More particularly, the present disclosure relates to non-pneumatic tires having spokes formed by a controlled thermal processing process. The resulting spokes may be formed from multiple layers. [Background technology]

[0002] Various tire designs have been developed that allow the tire to run in an uninflated or under-inflated state. Non-pneumatic tires do not require inflation, while "run-flat tires" can continue to operate for extended periods and at relatively high speeds after being partially or completely deflated due to a puncture. Non-pneumatic tires may include support structures such as spokes or webbing that connect the lower ring to the upper ring. In some non-pneumatic tires, a circumferential tread may be attached to the upper ring of the tire.

[0003] Non-pneumatic tires can use high strength, high toughness materials to achieve performance requirements. Steel components can be used as load-bearing components in non-pneumatic tires because of the large number of options and formulation methods available to produce the desired properties. Summary of the Invention

[0004] In one embodiment, a method for manufacturing a non-pneumatic tire includes providing a lower ring, providing an upper ring, providing a plurality of steel plates, and heating the plurality of steel plates to a temperature of 1000°C to 1200°C. The method further includes stacking the plurality of steel plates one on top of the other to form a laminated steel plate having a first thickness, and rolling the laminated steel plate at a temperature of 900°C to 1100°C until the laminated steel plate has a second thickness that is less than the first thickness. The method also includes performing a first quench on the laminated steel plate and reheating the laminated steel plate to a temperature of 400°C to 500°C. The method further includes rolling the laminated steel plate until the laminated steel plate has a third thickness that is less than the second thickness, and air-cooling the laminated steel plate to room temperature. The method also includes reheating the laminated steel plate to a temperature of 790°C to 830°C, performing a second quenching of the laminated steel plate, and tempering the laminated steel plate at a temperature of 200°C to 300°C. The method also includes cutting the laminated steel plate into a plurality of laminated steel strips and forming the laminated steel strips into a plurality of laminated steel spokes, each of the plurality of laminated steel spokes having a first end and a second end. The method also includes connecting the first end of each of the plurality of laminated steel spokes to a lower ring and connecting the second end of each of the plurality of laminated steel spokes to an upper ring. The method further includes applying a tread layer to an upper surface of the upper ring.

[0005] In another embodiment, a non-pneumatic tire includes a lower ring having a first diameter and an upper ring coaxial with the lower ring and having a second diameter greater than the first diameter. The non-pneumatic tire also includes a plurality of spokes extending from the lower ring to the upper ring, each of the plurality of spokes having a first end connected to the lower ring and a second end connected to the upper ring. Each of the plurality of spokes is formed from a plurality of steel layers, each layer of steel extending from the first end of the spoke to the second end of the spoke. The plurality of steel layers includes at least one layer of a first steel having a first carbon content, a first strength, and a first elongation. The plurality of steel layers also includes at least one layer of a second steel having a second carbon content, a second strength, and a second elongation, the first carbon content being greater than the second carbon content, the first strength being greater than the second strength, and the first elongation being less than the second elongation.

[0006] In yet another embodiment, a method for manufacturing spokes for a non-pneumatic tire includes providing a steel plate, heating the steel plate to a temperature of at least 1000°C, and rolling the steel plate at a temperature of at least 900°C until the thickness of the steel plate is reduced by at least 80%. The method also includes performing a first quench of the steel plate and reheating the steel plate to a temperature of at least 400°C. The method further includes rolling the steel plate until the thickness of the steel plate is further reduced by at least 80%, air cooling the steel plate, and reheating the steel plate to a temperature of at least 790°C. The method also includes performing a second quench of the steel plate and tempering the steel plate at a temperature of at least 200°C. The method further includes cutting the steel plate into a plurality of steel strips and forming the steel strips into a plurality of steel spokes. [Brief explanation of the drawings]

[0007] The accompanying drawings, together with the detailed description provided below, illustrate structures that describe exemplary embodiments of the claimed invention. Similar elements are identified with the same reference numerals. It should be understood that elements shown as a single component may be replaced by multiple components, and that elements shown as multiple components may be replaced by a single component. The drawings are not to scale, and the proportions of certain elements may be exaggerated for illustrative purposes. [Figure 1] FIG. 1 is a side view of one embodiment of a non-pneumatic tire. [Figure 2] FIG. 2 is a detailed view of a portion of FIG. 1, with some features removed for clarity. [Figure 3] FIG. 3 is a perspective view of the steel plate. [Figure 4] FIG. 4 is a time temperature graph of an exemplary method for treating steel sheet. [Figure 5A] FIG. 5A is a simplified diagram illustrating an exemplary stack of steel plates. [Figure 5B] FIG. 5B is a simplified diagram illustrating an exemplary stack of steel plates. [Figure 6A] FIG. 6A is a simplified diagram illustrating an additional exemplary stack of steel plates. [Figure 6B] FIG. 6B is a simplified diagram illustrating an additional exemplary stack of steel plates. [Figure 6C] FIG. 6C is a simplified diagram illustrating an additional exemplary stack of steel plates. [Figure 6D] FIG. 6D is a simplified diagram illustrating an additional exemplary stack of steel plates. [Figure 7A] FIG. 7A is a simplified diagram of a laminated spoke. [Figure 7B] FIG. 7B is a simplified diagram of a laminated spoke. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following contains definitions of selected terms used herein. The definitions include various examples or forms of components that fall within the scope of the term and that may be used for implementation. The examples are not intended to be limiting. Both singular and plural forms of a term may fall within the scope of the definition.

[0009] "Axial" and "axially" refer to directions parallel to the axis of rotation of the tire.

[0010] "Circumferential" and "circumferentially" refer to a direction extending along the perimeter of the surface of the tread perpendicular to the axial direction.

[0011] "Radial" and "radially" refer to directions perpendicular to the axis of rotation of the tire.

[0012] As used herein, "tread" refers to that portion of the tire that comes into contact with the road or ground under normal inflation and normal load.

[0013] It should be understood that while similar terms are used in the following description to describe typical tire components, the terms, of course, have slightly different connotations and one of ordinary skill in the art would not consider any of the following terms to be purely interchangeable with another term used to describe a typical tire component.

[0014] As used herein, directions are stated with reference to the tire's axis of rotation. The terms "upward" and "upwardly" refer to the general direction toward the tire's tread, and "downward" and "downwardly" refer to the general direction toward the tire's axis of rotation. Thus, when relative directional terms such as "upper" and "lower" or "top" and "bottom" are used in connection with elements, the "upper" or "top" element is spaced closer to the tread than the "lower" or "bottom" element. Additionally, when relative directional terms such as "above" or "below" are used in connection with elements, an element that is "above" another element is closer to the tread than the other element.

[0015] The terms "inner" and "inwardly" refer to the general direction toward the tire's equatorial plane, and "outer" and "outwardly" refer to the general direction away from the tire's equatorial plane, toward the tire's sides. Thus, when relative directional terms such as "inner" and "outer" are used in connection with elements, the "inner" elements are spaced closer to the tire's equatorial plane than the "outer" elements.

[0016] 1 and 2 illustrate one embodiment of a non-pneumatic tire 10. The non-pneumatic tire 10 is merely an exemplary illustration and is not intended to be limiting. In the illustrated embodiment, the non-pneumatic tire 10 includes a generally annular lower ring 20. The lower ring 20 can engage a vehicle hub (not shown) for mounting the tire 10 to a vehicle. The lower ring 20 can be made from a polymeric material, an elastomeric material, a metal, a composite material composed of a polymer reinforced with glass or carbon fiber, or any other desired material or combination of materials.

[0017] The non-pneumatic tire 10 further includes a generally annular upper ring 30. The upper ring 30 has a diameter larger than that of the lower ring 20 and is substantially coaxial with the lower ring 20. The upper ring 30 may be made from a polymeric material, an elastomeric material, a metal, a composite material composed of a polymer reinforced with glass or carbon fiber, or any other desired material or combination of materials. The lower ring 20 and the upper ring 30 may be composed of the same material or different materials.

[0018] A circumferential tread 40 is attached to the upper ring 30. The circumferential tread 40 may be attached to the upper ring 30 adhesively, mechanically, or in any other desired arrangement. The circumferential tread 40 may be made of rubber and may include tread elements (not shown) such as grooves, ribs, blocks, lugs, sipes, studs, or any other desired elements. The tread band may include a filament assembly.

[0019] In the illustrated embodiment, the circumferential tread 40 is shown as a single layer. In alternative embodiments, the tread may be a multi-layer band. Such a multi-layer tread band may include one or more layers of substantially inextensible material. The layers may be formed from sheets of material, cords of material, filaments of material, or any other desired arrangement. In other alternative embodiments, the multi-layer tread band may include layers of extensible material, such as an elastomer. In one exemplary embodiment, the tread band may include a pair of inextensible layers separated by a layer of extensible material. In other alternative embodiments, the tread band may include bands referred to as shear bands, shear elements, or thin annular high strength band elements.

[0020] The spokes 50 connect the lower ring 20 to the upper ring 30. Each spoke 50 has a first end connected to the lower ring 20 and a second end connected to the upper ring 30. In the illustrated embodiment, the spokes 50 are arranged in two axially spaced groups of spokes, including a first group of spokes extending in a first direction and a second group of spokes extending in a second direction opposite the first direction. In an alternative embodiment, a single group of spokes may be used, with each spoke extending in the same direction. In another alternative embodiment, three or more axially spaced groups of spokes may be used.

[0021] In the illustrated embodiment, a first end of each spoke 50 is directly connected to the lower ring 20. The first ends of the spokes 50 may be connected to the lower ring 20 by welding, brazing, soldering, adhesives, mechanical fasteners (e.g., bolts, rivets), key and keyway connections, or any other desired arrangement. The second end of each spoke 50 is connected to a flexible member 60, which is in turn connected to the upper ring 30. In other words, the second end of each spoke 50 is indirectly connected to the upper ring 30.

[0022] The flexible member 60 may be fabricated from a polymer (e.g., urethane or rubber), a thin curved piece of metal, or any other desired material or combination of materials. In the illustrated embodiment, the flexible member 60 is provided as a rectangular parallelepiped and is positioned such that the end of the flexible member 60 is aligned with the second ends of the spokes 50. In other alternative embodiments, the flexible member may be positioned such that the end of the flexible member is set back from the second ends of the spokes, or such that the end of the flexible member extends beyond the second ends of the spokes. In yet other alternative embodiments, the flexible member may be replaced with a mechanical pin joint (i.e., hinge).

[0023] The flexible members 60 include spoke-facing surfaces and ring-facing surfaces. The spoke-facing surfaces of the flexible members 60 are attached to the spokes 50, and the ring-facing surfaces are attached to the top ring 30. Attachment between the flexible members 60 and the spokes 50 or between the flexible members 60 and the top ring 30 may be achieved using welding, brazing, soldering, adhesives, mechanical fasteners (e.g., bolts, rivets), key / keyway connections, or any other desired arrangement. For example, attachment may be achieved by pouring urethane directly onto the spokes, with or without the spokes first being coated with a primer.

[0024] While the illustrated embodiment shows a first end of each spoke 50 connected directly to the lower ring 20 and a second end connected indirectly to the upper ring 30, it should be understood that other arrangements may be used. For example, in an alternative embodiment, the first end of each spoke is indirectly connected to the lower ring and the second end of each spoke is directly connected to the upper ring. In another alternative embodiment, the first end of each spoke is indirectly connected to the lower ring and the second end of each spoke is similarly indirectly connected to the upper ring. In yet another alternative embodiment, the first end of each spoke is directly connected to the lower ring and the second end of each spoke is similarly directly connected to the upper ring.

[0025] FIG. 2 is a detailed view of a portion of the non-pneumatic tire 10, with some features removed for clarity. As can be seen from this view, each spoke 50 has an approximate circumferential thickness t. The thickness t can be between 1.5 mm and 5 mm. In one particular embodiment, each spoke 50 has a thickness t of 3 mm. In the illustrated embodiment, each spoke 50 has a constant thickness t. In alternative embodiments, the thickness of the spoke can vary between the first end and the second end. For example, the spoke may have a relatively thick portion at the first end and the second end and a relatively thin portion between the ends. Each spoke also has an approximate axial width.

[0026] In one embodiment, each of the spokes 50 is constructed from steel. More specifically, the spokes 50 are constructed from ultra-high strength steel produced by a Thermo-Mechanically Controlled Process (TMCP) production method. In one particular embodiment, the spokes 50 are laminated spokes constructed from multiple layers of steel.

[0027] The basis behind TMCP steel production is that a controlled temperature profile within the steel plate ensures the development of the desired steel microstructure. The simultaneous use of severe warm rolling is used to mechanically reduce the gauge of the steel, reduce the grain size of constituent materials within the matrix, and accelerate the production of a microstructure capable of achieving ultra-high strength (i.e., strength of 2000 MPa or greater) while maintaining acceptable elongation (i.e., elongation of at least 3%). TMCP has long been used for large-scale applications, including heavy plates such as ship hulls. However, TMCP is challenging for thinner gauges because the properties of the resulting product are more difficult to control. For this reason, TMCP has long been considered unsuitable for smaller applications requiring thin steel plates, such as sheets less than one centimeter thick.

[0028] FIG. 3 is a perspective view of an exemplary steel plate 100 used to form multiple spokes. In one embodiment, a single steel plate is used to form the spokes. In an alternative embodiment, multiple steel plates can be stacked and processed to ultimately form the laminated spokes. The steel plate 100 can be formed from any number of steel grades. For example, the steel plate 100 can be Damascus or Katana steel, or a similar steel grade. Such steel grades have a high carbon content of at least 0.60%, ultra-high strength (i.e., at least 2000 MPa, or 290 ksi ultimate tensile strength), and a moderate elongation (i.e., at least 3% elongation). As another example, the steel plate 100 can be formed from a steel having a low-to-medium carbon content of less than 0.60%, high strength (i.e., 1200-2000 MPa, or 174-290 ksi ultimate tensile strength), and high elongation (i.e., at least 10% elongation). In another example, plates of both steel grades can be used.

[0029] Plate 100 has an initial thickness t0 that is significantly greater than the thickness t of each spoke 50. If spokes 50 are formed from a single steel plate 100, the plate may have an initial thickness t0 of 50 mm to 500 mm. If spokes 50 are formed from multiple stacked plates, the stack may have a combined initial thickness of 50 mm to 500 mm.

[0030] 4 is a time-temperature graph of an exemplary method of treating steel sheet using TMCP. The graph is not to scale. While specific temperature values ​​and other designations are present on the graph, it should be understood that these values ​​are merely exemplary.

[0031] The process begins by heating the steel plate 100 (or plates) to an elevated temperature. In a time-temperature graph, the plate is heated to a temperature of 1200°C and then held at that temperature for two hours. In one embodiment, it takes 30 minutes for each inch of thickness to reach a temperature of 1200°C. In an alternative embodiment, the plate may be heated to a temperature between 900°C and 1300°C and held at that temperature for two hours. Heating the plate to such a temperature homogenizes the steel. The temperature may be selected based on the carbon content in the steel. A temperature between 900°C and 1300°C may be appropriate for steel with a carbon content of 0.15% to 0.80%.

[0032] If multiple plates are used, the multiple steel plates are stacked one on top of the other during the initial heating step or immediately after the heating step, resulting in a laminated steel plate.

[0033] 5A and 5B are simplified diagrams showing an exemplary steel plate stack 200. FIG. 5A illustrates a steel plate stack 200A having alternating layers of high-carbon steel plates 210 and low-carbon steel plates 220. Each high-carbon steel plate 210 has a carbon content of at least 0.60%, while the low-carbon steel plates 220 have a carbon content of less than 0.60%. In FIG. 5A, the high-carbon steel plates 210 form the outermost layers, sandwiching the low-carbon steel plates 220.

[0034] The high-carbon steel sheet 210 may be referred to as a plurality of first steel sheets having a first strength and a first elongation, and the low-carbon steel sheet 220 may be referred to as a plurality of second steel sheets having a second strength and a second elongation. The first strength is greater than the second strength, and the second elongation is greater than the first elongation. For example, the first strength of the finished product may be at least 2000 MPa, while the second strength is between 1200 and 2000 MPa. The first elongation of the finished product may be at least 3%, while the second elongation is at least 10%.

[0035] Figure 5B illustrates a steel plate stack 200B having alternating layers of high carbon steel plates 210 and low carbon steel plates 220. The high carbon steel plates 210 and low carbon steel plates 220 are substantially the same as those described above with respect to Figure 5A. In Figure 5B, the low carbon steel plates 220 form the outermost layers, sandwiching the high carbon steel plates 210.

[0036] Figures 5A and 5B each show three layers for illustrative purposes. In practice, it may be desirable to form more layers of spokes. Figures 6A-6D are simplified diagrams showing additional exemplary steel layers. Figure 6A illustrates a steel plate stack 200C having three high carbon steel plates 210 and three low carbon steel plates 220. In this embodiment, one high carbon steel plate 210 forms a first outer layer, while one low carbon steel plate 220 forms a second outer layer opposite the first outer layer.

[0037] 6B illustrates a steel plate stack 200D having five high carbon steel plates 210 and five low carbon steel plates 220. In this embodiment, one high carbon steel plate 210 forms a first outer layer, while one low carbon steel plate 220 forms a second outer layer opposite the first outer layer.

[0038] 6C illustrates a steel plate stack 200E having ten high carbon steel plates 210 and ten low carbon steel plates 220. In this embodiment, one high carbon steel plate 210 forms a first outer layer, while one low carbon steel plate 220 forms a second outer layer opposite the first outer layer.

[0039] 6D illustrates a steel plate stack 200F having 20 high carbon steel plates 210 and 20 low carbon steel plates 220. In this embodiment, one high carbon steel plate 210 forms a first outer layer, while one low carbon steel plate 220 forms a second outer layer opposite the first outer layer.

[0040] The embodiments illustrated in FIGS. 5A and 5B and 6A-6D are merely exemplary and are not intended to be limiting. In one known embodiment, each steel spoke is made from a stack of 10-20 steel plates. In another known embodiment, each steel spoke is made from a stack of 20-30 steel plates. In yet another known embodiment, each steel spoke is made from a stack of 30-40 steel plates. In yet another known embodiment, each steel spoke is made from a stack of 40-50 steel plates. In other words, each steel spoke can be made from a stack of 10-50 steel plates. In either case, the layers may alternate between a first steel plate and a second steel plate. In alternative embodiments, it may be desirable to use consecutive plates of the same material. In other alternative embodiments, it may be desirable to use three or more different types of steel plates. The outer layers of each stack may be formed of the same steel grade or different steel grades.

[0041] Returning to FIG. 4, after the initial heating step is complete, the steel plate 100 (or stack of steel plates 200) is rolled at a normalized temperature of 900°C to 1100°C until the thickness of the plate 100 (or stack of steel plates) is reduced by 90%. This rolling step is sometimes referred to as a hot rolling process. In other embodiments, the plate may be rolled until its thickness is reduced by 80 to 99%. In other words, the thickness of the steel plate 100 (or stack of steel plates 200) after this rolling process may be 1% to 20% of its original thickness. In one embodiment, the thickness of the steel plate or stack of steel plates is 10 mm to 100 mm at this stage.

[0042] After the rolling process, the steel sheet 100 or (stack of steel sheets 200) is rapidly cooled by a first quench. As shown in the temperature-time graph, the quench is an oil quench. The oil quench cools the steel at a rate of 5°C / min to 10°C / min, creating a martensitic structure within the steel sheet 100. In other embodiments, other quenchants such as glycol, water, or nitrogen can be used.

[0043] The steel plate 100 (or stack of steel plates 200) is then subjected to a temperature forming ("TF") step in which the plates are reheated to a temperature of 500°C at a rate of 5°C / min to 10°C / min. The heating rate will affect the grain growth within each plate.

[0044] In another embodiment, the plate is reheated to a temperature between 400° C. and 600° C. Importantly, the plate is reheated to a temperature below the point at which ferrite transforms to austenite, represented as A1 on the temperature-time graph.

[0045] While the steel is still hot, the steel plate 100 (or stack of steel plates 200) is rolled again. This process is sometimes called strong warm rolling. As shown in the time-temperature graph of FIG. 4, the steel plate 100 (or stack of steel plates 200) is rolled until its thickness is reduced by a further 85%. In other embodiments, the plate is rolled until its thickness is reduced by 80-99%. In other words, the thickness of the steel plate 100 (or stack of steel plates 200) may be 1%-20% of its previous thickness. This thickness is the final plate gauge. In one embodiment, the thickness of the steel plate or stack of steel plates is 2 mm-5 mm at this stage. If a stack of steel plates is used, each layer of steel may be 0.04 mm-0.5 mm (40-500 μm) at this stage.

[0046] This severe warm rolling process can result in the production of a microstructure of ultra-fine elongated ferrite grains and fine carbides that are uniformly distributed throughout the matrix. These low temperature deformations require a significant amount of force because the steel is quite hard, but they are necessary to introduce plastic deformation into the steel.

[0047] After the warm rolling process is complete, the steel sheet 100 (or stack of steel sheets 200) is air-cooled until it reaches room temperature. After cooling, the steel sheet 100 (or stack of steel sheets 200) is reheated again, this time to a temperature A2 above the point at which ferrite transforms to austenite. For example, the sheet may be heated to a temperature of 790°C to 830°C. The sheet is then held at this temperature to allow for decomposition of carbides and subsequent grain size growth in the final martensite. In one embodiment, this may occur in less than 10 minutes. In other embodiments, it may be held for a significantly longer period of time.

[0048] The steel plate 100 (or stack of steel plates 200) is then quenched a second time. In one embodiment, the second quench is a water quench, decreasing the temperature at a rate of 10°C / min to 20°C / min, depending on the water temperature. In alternative embodiments, the second quench may be performed using oil, glycol, or nitrogen. The second quench produces the final ultrafine-grained martensite structure. The steel plate 100 (or stack of steel plates 200) is then tempered at a relatively low temperature (200-300°C) to relieve internal stresses and improve the overall elongation of the material. The steel plate 100 (or stack of steel plates 200) is then air-cooled once more to room temperature.

[0049] After the TMCP process is complete, the steel sheet 100 (or stack of steel sheets 200) can then be formed into a spoke. Figures 7A and 7B are simplified diagrams of a laminated spoke 300. In both figures, each layer extends along the entire length of the spoke 300, from a first end of the spoke to a second end of the spoke.

[0050] Figure 7A illustrates a spoke 300A having a high carbon steel layer 310 surrounding a low carbon steel layer 320. This arrangement corresponds to the stack of steel plates 200A shown in Figure 5A.

[0051] Figure 7B illustrates a spoke 300B having a low carbon steel layer 320 surrounding a high carbon steel layer 310. This arrangement corresponds to the stack of steel plates 200A shown in Figure 5A.

[0052] It should be understood that the spokes 300 of Figures 7A and 7B are merely exemplary. The spokes may be formed from a single plate or from any of the stacks of plates described above.

[0053] To form the spokes, the operator cuts the steel plate 100 (or stack of steel plates 200) into a plurality of steel strips. The steel strips may be solid steel strips or laminated steel strips. The operator then forms the laminated steel strips into a plurality of laminated steel spokes, each of the plurality of laminated steel spokes having a first end and a second end. In one embodiment, the operator forms at least one bend in the steel strip to form the spokes. In the embodiment shown in FIGS. 7A and 7B, the operator forms multiple bends in the steel strip to form spokes 300. The operator then connects the first end of each of the steel spokes to a lower ring and the second end of each of the plurality of laminated steel spokes to an upper ring. This forms a non-pneumatic tire structure, such as the structure shown in FIG. 1. The operator can then apply a tread layer to the top surface of the upper ring to complete the construction of the non-pneumatic tire.

[0054] In one embodiment, the spokes are formed after the TF process but before the reheating and second quenching. In another embodiment, the spokes are formed after the reheating and second quenching. Forming the spokes before the reheating and second quenching may prevent the part from fracturing during forming.

[0055] The terms "includes" or "including," to the extent used in this specification or the claims, are intended to be inclusive, similar to the term "comprising," as interpreted when used as a transitional word in a claim. Furthermore, to the extent the term "or" is used (e.g., A or B), it is intended to mean "A or B, or both." Where applicants intend to indicate "only A or B but not both," the term "only A or B but not both" is used. Thus, the use of the term "or" herein is inclusive, not exclusive. See Bryan A. Garner, A Dictionary of Modern Legal Usage 624 (2d. Ed. 1995). Also, the terms "in" or "into," to the extent used in this specification or the claims, are intended to additionally mean "on" or "onto." Furthermore, to the extent the term "connect" is used in this specification or the claims, it is intended to mean not only "directly connected to," but also "indirectly connected to," such as connected through another component or components.

[0056] While the present application has been illustrated by the description of its embodiments, and those embodiments have been described in considerable detail, it is not the intention of applicants to restrict or in any way limit the scope of the appended claims to such details. Additional advantages and modifications will be readily apparent to those skilled in the art. Therefore, the present application in its broader aspects is not limited to the specific details, representative apparatus and methods, and examples shown and described. For example, each spoke may be provided with a rubber coating to cushion impact when contact occurs between adjacent spokes. Thus, departures may be made from such details without departing from the spirit or scope of applicants' general inventive concept.

Claims

1. 1. A method of manufacturing a non-pneumatic tire, comprising: providing a lower ring; providing an upper ring; providing a plurality of steel plates; heating the plurality of steel plates to a temperature of 1000°C to 1200°C; stacking the plurality of steel plates one above the other to form a laminated steel plate having a first thickness; rolling the laminated steel sheet at a temperature of 900°C to 1100°C until the laminated steel sheet has a second thickness that is thinner than the first thickness; performing a first quenching of the laminated steel plate; Reheating the laminated steel plate to a temperature of 400°C to 500°C; rolling the laminated steel sheet until the laminated steel sheet has a third thickness that is thinner than the second thickness; Air-cooling the laminated steel sheet to room temperature; Reheating the laminated steel plate to a temperature of 790°C to 830°C; performing a second quenching of the laminated steel plate; Tempering the laminated steel sheet at a temperature of 200 ° C to 300 ° C; Cutting the laminated steel plate into a plurality of laminated steel strips; forming the laminated steel strip into a plurality of laminated steel spokes, each of the plurality of laminated steel spokes having a first end and a second end; connecting the first end of each of the plurality of laminated steel spokes to the lower ring; connecting the second end of each of the plurality of laminated steel spokes to the upper ring; and applying a tread layer to an upper surface of said upper ring.

2. the plurality of steel plates includes a plurality of first steel plates having a first strength and a first elongation rate, and a plurality of second steel plates having a second strength and a second elongation rate; the first intensity is greater than the second intensity; and The method of claim 1 , wherein the second stretch ratio is greater than the first stretch ratio.

3. 3. The method of claim 2, wherein the first strength is at least 2000 MPa and the second strength is between 1200 and 2000 MPa.

4. 3. The method of claim 2, wherein the first stretch ratio is at least 3% and the second stretch ratio is at least 10%.

5. The method of claim 1, wherein the second thickness is 1 to 20% of the first thickness and the third thickness is 1 to 20% of the second thickness.

6. The method of claim 1, wherein the third thickness is between 2 and 5 mm.

7. The method of claim 1 , wherein the first quench is performed with oil.

8. The method of claim 1 , wherein the second quench is performed with water.

9. A non-pneumatic tire, a lower ring having a first diameter; an upper ring having a second diameter greater than the first diameter and coaxial with the lower ring; a plurality of spokes extending from the lower ring to the upper ring; each of the plurality of spokes having a first end connected to the lower ring and a second end connected to the upper ring; each of the plurality of spokes is formed from a plurality of layers of steel; each of the plurality of steel layers extending from the first end of the spoke to the second end of the spoke; the plurality of steel layers includes at least one layer of a first steel having a first carbon content, a first strength, and a first elongation; the plurality of steel layers includes at least one layer of a second steel having a second carbon content, a second strength, and a second elongation; the first carbon content is greater than the second carbon content; the first intensity is greater than the second intensity; and The first stretch rate is less than the second stretch rate.

10. 10. The non-pneumatic tire of claim 9, wherein the first end of each of the plurality of spokes is directly connected to the lower ring and the second end of each of the plurality of spokes is indirectly connected to the upper ring.

11. 10. The non-pneumatic tire of claim 9, wherein the plurality of steel layers comprises at least 10 steel layers.

12. 10. The non-pneumatic tire of claim 9, wherein said plurality of steel layers comprises between 30 and 50 steel layers.

13. 10. The non-pneumatic tire of claim 9, wherein each of said plurality of spokes has a thickness of less than 5 mm.

14. 10. The non-pneumatic tire of claim 9, wherein the first carbon content is at least 0.60% and the second carbon content is less than 0.60%.

15. 10. The non-pneumatic tire of claim 9, wherein the plurality of layers of steel comprises alternating layers of the first steel and the second steel.

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