Tire with band layer

Abstract

A method of making a tire tread includes providing a sheet of material and forming the sheet of material into a cylinder such that a first edge of the sheet of material contacts a second edge of the sheet of material. The method also includes welding the first edge to the second edge to form a seamed cylindrical weld joint and providing a tread rubber about the seamed cylinder.

Description

[Technical Field]

[0001] The present disclosure relates to a tire and a method for manufacturing the same, and more particularly to a tire having a band layer attached to a tread rubber layer, and a method for manufacturing the same. [Background technology]

[0002] Various tire designs have been developed that allow the tire to run in an uninflated or underinflated state. Non-pneumatic tires do not require inflation, while "run-flat tires" can continue to operate at relatively high speeds for extended periods of time after a puncture that completely or partially loses pressurized air. Non-pneumatic tires may include multiple spokes, webbing, or other support structures connecting a lower ring to an upper ring. In some non-pneumatic tires, a circumferential tread may be wrapped around the upper ring of the tire. Summary of the Invention [Problem to be solved by the invention]

[0003] The circumferential tread of the tire may contain a shear element having an elastic region disposed between upper and lower inelastic regions. The shear element may also be referred to as a shear band, a tread band, or a thin, annular, high-strength band element. When used in a pneumatic tire, the shear element acts as a tension member when the tire is inflated. When used in a non-pneumatic tire or a pneumatic tire in an uninflated or partially inflated state, the shear element acts as a structural compression member.

[0004] In one embodiment, a non-pneumatic tire includes a lower ring having an axis of rotation and an upper ring coaxial with the lower ring. The non-pneumatic tire further includes a support structure extending from the lower ring to the upper ring and a circumferential tread extending around the upper ring. The circumferential tread includes a band layer formed by a seamed cylinder constructed of a single material and a tread rubber layer attached directly to the band layer.

[0005] In another embodiment, a method of making a non-pneumatic tire includes providing an assembly having a lower ring, an upper ring coaxial with the lower ring, and a support structure extending from the lower ring to the upper ring. The method also includes providing a sheet of material and forming the sheet of material into a cylinder such that a first edge of the sheet of material contacts a second edge of the sheet of material. The method further includes welding the first edge to the second edge to form a seamed cylinder weld joint. The method also includes placing the seamed cylinder around the upper ring and providing a tread rubber around the seamed cylinder.

[0006] In yet another embodiment, a method of making a tire tread includes providing a sheet of material and forming the sheet of material into a cylinder such that a first edge of the sheet of material contacts a second edge of the sheet of material. The method also includes welding the first edge to the second edge to form a seamed cylinder weld joint, and providing a tread rubber around the seamed cylinder. [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 front view of an undeformed non-pneumatic tire. [Figure 2] FIG. 2 is a front view of the non-pneumatic tire of FIG. 1 deforming when subjected to a load. [Figure 3] FIG. 3 is a schematic diagram illustrating a partial cross-sectional view along line 3-3 of FIG. [Figure 4A] FIG. 4A is a front plan view of one embodiment of a sheet of metal or high strength polymer material. [Figure 4B] FIG. 4B is a perspective view of one embodiment of a seamed cylinder formed from the sheet of FIG. 4A. [Figure 5A] FIG. 5A is a front plan view of an alternative embodiment of a sheet of metal or high strength polymer material. [Figure 5B] FIG. 5B is a perspective view of one embodiment of a cylinder formed from the sheet of FIG. 5A. [Figure 6A] FIG. 6A is a front plan view of another alternative embodiment of a sheet of metal or high strength polymer material. [Figure 6B] FIG. 6B is a perspective view of one embodiment of a cylinder formed from the sheet of FIG. 6A. [Figure 7A] FIG. 7A is a cross-sectional view of one embodiment of a counterflow forming system for forming a cylinder. [Figure 7B] FIG. 7B is a front view of the backflow forming system of FIG. 7A. [Figure 8A] FIG. 8A is a perspective view of the cylinder of FIG. 6B, with arrows indicating one embodiment of the direction of travel during the flow-forming process. [Figure 8B] FIG. 8B is a perspective view of the cylinder of FIG. 6B, with arrows indicating an alternative embodiment of the direction of travel during the flow-forming process. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following contains definitions of selected terms employed 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 the 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 one of the following terms to be simply interchangeable with another term used to describe typical tire components.

[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 side. 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 that engages a rim (not shown) on which the tire 10 is mounted. The generally annular lower ring 20 has an inner surface 23 and an outer surface 24 and may be made from an elastomeric material or metal.

[0017] The non-pneumatic tire 10 further includes a generally annular upper ring 30 surrounding an interconnected web 40, which is a support structure connected to the generally annular lower ring 20. In an alternative embodiment, a plurality of spokes or other support structures connect the lower ring to the upper ring. The upper ring 30 can be configured to deform in a region 48 around and including the contact patch region 32 (see FIG. 2), thereby reducing vibrations and improving ride comfort.

[0018] In one embodiment, the generally annular lower ring 20 and the generally annular upper ring 30 are made from the same material as the interconnected webs 40. In an alternative embodiment, at least one of the generally annular lower ring, the generally annular upper ring, and the interconnected webs are made from a different material. As shown in FIG. 1 , the generally annular upper ring 30 can have a radially outer surface 34 to which a tread carrying layer 70 is attached. Attachment can be by adhesive or using other methods commonly available in the art.

[0019] In the illustrated embodiment, the interconnected webs 40 have at least two diametrically adjacent layers 56, 58 of web elements 42 that define a plurality of generally polygonal openings 50. In other embodiments (not shown), other web configurations may be used. In another embodiment (not shown), spokes or other support structures may be used in place of the webs.

[0020] 3 is a schematic diagram illustrating a partial cross section of one embodiment of a non-pneumatic tire 100. In this embodiment, the non-pneumatic tire 100 includes a tire structure having a lower ring 110, an upper ring 120, and a support structure 130 extending from the lower ring to the upper ring. In one embodiment, the support structure 130 is a webbing, such as the webbing shown in FIGS. 1 and 2. In an alternative embodiment, the support structure includes a plurality of spokes. However, it should be understood that any support structure may be used.

[0021] The non-pneumatic tire 100 includes a circumferential tread having the same width as the top ring 120. The circumferential tread includes a band layer 140 constructed of a single material. A tread rubber layer 150 is attached directly to the band layer 140. In an alternative embodiment (not shown), the circumferential tread is wider than the top ring. In another alternative embodiment (not shown), the top ring is wider than the circumferential tread.

[0022] The illustrated structure carries an applied load by resisting bending about its neutral axis. The bending of the band layer 140 helps carry the load on the non-pneumatic tire 100. If metal or other lossless materials are used for the band layer 140, the rolling resistance and heat generation of the assembly can be reduced. This is a departure from conventional polymer shear layers with steel cord plies. Such polymer shear layers offer load-carrying capabilities at the expense of high rolling resistance and heat generation.

[0023] The band layer 140 is not formed from layers of separate materials, although the single material of the band layer 140 may be a composite material or a blend of materials. In one embodiment, the band layer 140 is constructed from steel. In one particular embodiment, the band layer 140 is constructed from ultra-high strength steel. Other exemplary materials include, but are not limited to, other metals such as rubber, aluminum, brass, copper, and stainless steel, or polymeric materials including polyurethane, polyester, and polyvinyl chloride (PVC).

[0024] Good performance can be achieved with band layers constructed from materials with high ultimate tensile strength and low surface roughness. In one embodiment, the band layer is constructed from a material with an ultimate tensile strength of at least 60,000 pounds force per square inch (i.e., 60 ksi or 410 MPa). In another embodiment, the band layer is constructed from a material with an ultimate tensile strength of at least 120,000 pounds force per square inch (i.e., 120 ksi or 830 MPa). In yet another embodiment, the band layer is constructed from a material with an ultimate tensile strength of at least 200,000 pounds force per square inch (i.e., 200 ksi or 1400 MPa). Band layers constructed from materials with high ultimate tensile strength have better fatigue life.

[0025] Additionally, in one embodiment, the band layer is made of a material having an average surface roughness of less than 1000 microinches (i.e., 25 microns). In another embodiment, the band layer is made of a material having an average surface roughness of less than 64 microinches (i.e., 1.6 microns). In yet another embodiment, the band layer is made of a material having an average surface roughness of less than 32 microinches (i.e., 0.8 microns). While a rough surface finish may be better for adhesion, a finer finish has been found to be better for fatigue life.

[0026] The above-identified ultimate tensile strengths and average surface roughnesses may be found in high-strength steels prepared through shot peening or laser shock peening processes. The high-strength steels may be specialty steels and may receive special heat treatments. Aluminum and titanium may also exhibit the above-identified ultimate tensile strengths and average surface roughnesses.

[0027] In the illustrated embodiment, the band layer 140 has a band thickness T B The tread rubber layer 150 has a band thickness T B Tread thickness greater than T TIn one known embodiment, the band thickness is between 0.010 inches and 0.300 inches (0.254 mm and 7.62 mm). However, other configurations may be used. The thickness of the band layer and tread layer may be selected to provide desired performance for the non-pneumatic tire. For example, it may be desirable to balance the bending stiffness of the band layer with the thickness of the band layer to adjust the bending moment about the neutral axis to carry a desired load at a desired deflection.

[0028] Selecting the thickness of the band layer and tread rubber layer also allows the tire designer to select the location of the neutral axis of the circumferential tread. For example, the location of the neutral axis may be selected so that the circumferential tread has different bending stiffness in different directions. If the neutral axis is closer to the outer diameter of the tire, the leading and trailing edges of the contact patch will be more difficult to flex, thus increasing load-bearing capacity. However, when the tire rolls across an object, having a lower bending stiffness in that direction allows for easier handling and a more comfortable ride.

[0029] Other factors may be considered when selecting the material and thickness of each layer. For example, it may be desirable to reduce the thickness of the band layer to reduce volume and weight and to reduce the amount of heat generated during tire rotation. However, it may be desirable to increase the thickness of the band layer to reduce stress in the band layer.

[0030] Additionally, it may be desirable to select the thickness and stiffness of the tread rubber layer and band layer to adjust the length of the contact patch.

[0031] Such cylinders may have a diameter of 20 to 50 inches (50 to 130 cm). In more particular embodiments, the cylinders have a diameter of 30 to 40 inches (75 to 100 cm). In one particular embodiment, the cylinders have a diameter of 36 inches (91 cm).

[0032] As noted above, the cylinder thickness may be between 0.010 inches and 0.300 inches (0.254 mm and 7.62 mm). In more specific embodiments, the cylinder thickness is between 0.020 inches and 0.150 inches (0.50 mm and 3.8 mm). In one particular embodiment, the cylinder thickness is 0.145 inches (3.68 mm).

[0033] As mentioned above, the cylinder may be made from steel. Exemplary steels include ultra-high strength steel, 4340 steel, or 1080 steel. Alternatively, the cylinder may be formed from an alloy.

[0034] Bands in the form of metal or high-strength polymers have been found to provide good results. Seamless metal cylinders have long been known to provide good results, as described in WO 2020 / 142665. Seamless metal cylinders can have a consistent thickness around their entire circumference, thereby minimizing stress concentrations. In contrast, cylinders with seams formed by a welding process have varying thicknesses at the seams, which can create stress concentrations. However, despite this known issue, testing has shown that seamed metal or high-strength polymer cylinders can provide surprisingly good results.

[0035] Seamed metal or high-strength polymer cylinders have additional manufacturing advantages over seamless cylinders. Forging a cylinder with a diameter of 20 to 50 inches and a thickness of 0.010 to 0.300 inches is difficult. Forging a cylinder with such dimensions can result in cracks, microcracks, or other irregularities. Therefore, in the preceding embodiment, seamless cylinders with diameters of 20 to 50 inches and thicknesses of 0.300 to 1 inch were produced by a rough forging process. The cylinders were then machined or turned to the desired thickness of 0.010 to 0.300 inches. The machining or turning may be performed in multiple steps. The cylinders may also be subjected to heat treatment and polishing steps. Such processes may be time-consuming and may generate undesirable waste.

[0036] In another prior embodiment, a seamless cylinder having a diameter of 20 to 50 inches and a thickness of 0.300 to 1 inch was produced by a rough forging process. The thickness of the cylinder was then reduced by a cold forming process.

[0037] In contrast, seamed metal or high-strength polymer cylinders may be formed from sheets of metal or high-strength polymer having thicknesses of 0.010 inches to 0.300 inches. Compared to forged metal cylinders, sheets of such thickness are less likely to develop cracks, microcracks, or other irregularities. Therefore, fabricating seamed metal or high-strength polymer cylinders from thin sheets of metal or high-strength polymer may be advantageous because less processing is required after such cylinders are formed, and the resulting cylinders may have stress concentrations comparable to or even less than seamless metal cylinders. However, it should be understood that the sheets may have greater thicknesses that are reduced during the manufacturing process. For example, the sheets may have an initial thickness that is reduced from 0.300 inches to 2 inches.

[0038] In one embodiment, the seamed metal cylinder is formed from flat steel stock. In another embodiment, the seamed metal cylinder is formed from flat steel stock of other metals, such as aluminum, tin, brass, nickel, copper, titanium, or other metals or alloys, particularly high strength alloys. In yet another embodiment, the seamed cylinder may be formed from a high strength polymer.

[0039] 4A is a front plan view of one embodiment of flat stock or sheet 200A of metal or high-strength polymer having a rectangular shape. In one embodiment, sheet 200A is formed to specified dimensions as a single plate. In an alternative embodiment, the sheet is formed as an elongated sheet that is cut to specified dimensions. Sheet 200A is then rolled longitudinally so that first end or edge 210A meets second end or edge 220A to form cylinder 300A.

[0040] 4B is a perspective view of cylinder 300A. As can be seen in this view, first end 210A and second end 200A of rectangular sheet 200A form longitudinal seam 310A. Longitudinal seam 310A may then be welded. In one embodiment, welded seam 310A is formed using a technique that produces a joint of the same composition as the base material, such as friction stir welding, laser welding, electron beam welding, or induction welding techniques. The selected process may eliminate the need for filler materials and maintain the high strength and toughness of the material of sheet 200A.

[0041] 5A is a front plan view of an alternative embodiment of flat stock or sheet 200B of metal or high-strength polymer having a parallelogram shape. In one embodiment, sheet 200B is formed to specified dimensions as a single plate. In an alternative embodiment, the sheet is formed as an elongated sheet that is cut to specified dimensions. Sheet 200B is then rolled so that first end or edge 210B meets second end or edge 220B to form cylinder 300B.

[0042] 5B is a perspective view of cylinder 300B. As can be seen in this view, first end 210B and second end 200B of parallelogram-shaped sheet 200B form diagonal seam 310B. Diagonal seam 310B may then be welded using one of the welding processes described above for longitudinal seams.

[0043] 6A is a front plan view of another alternative embodiment of flat stock or sheet 200C of metal or high-strength polymer having an elongated parallelogram shape. In one embodiment, sheet 200C is formed to specified dimensions as a single plate. In an alternative embodiment, the sheet is formed as an elongated sheet that is cut to specified dimensions. Sheet 200C is then spiraled such that first side or edge 210C meets second side or edge 220C to form a spiral along the resulting cylinder 300C.

[0044] 6B is a perspective view of cylinder 300C. As can be seen in this view, first side 210C and second side 200C of the elongated parallelogram shape form a helical seam 310C of cylinder 300C. Helical seam 310C may then be welded using one of the welding processes described above for longitudinal seams.

[0045] The examples shown in Figures 4-6 are not intended to be limiting. It should be understood that other seams may be used. For example, the seam may be non-linear, such as a curved or wavy seam.

[0046] In one embodiment, no post-fabrication processing is performed after the seam is welded. In other words, no machining, sizing, or heat treating is performed. In an alternative embodiment, a stress relief operation may be performed after the welding process to relieve any stresses after the formation of the cylinder. For example, a cold forming process may be performed.

[0047] In one embodiment, the cold forming process is a counterflow forming process, as illustrated in Figures 7A and 7B. Figure 7A illustrates a cross-sectional view of a counterflow forming system 400, and Figure 7B illustrates a front view of the counterflow forming system 400. In this system, a seamed cylinder 410 (such as any one of cylinders 300A, 300B, and 300C described above) is placed on a mandrel 420 having a spindle 430. After the cylinder 410 is placed on the mandrel 420, the spindle 430 rotates the mandrel 420 and cylinder 410 in a first direction. A plurality of rollers 440 engage the cylinder 410, and the rollers 440 rotate in a second direction opposite the first direction. A tailstock 450 provides support to the system.

[0048] The rollers 440 are then moved toward the spindle. In one embodiment, the rollers 440 are spaced apart so that the thickness of the welded seam is reduced to the same thickness as the rest of the cylinder 410, while the thickness of the wall of the cylinder 410 remains unchanged. In another embodiment, the rollers 440 are spaced apart so that the movement of the spindle reduces both the thickness of the welded seam and the thickness of the wall of the cylinder 410. In this embodiment, the movement of the rollers 440 also moves the material of the cylinder in a direction opposite to the direction of travel of the rollers 440.

[0049] In the illustrated embodiment, three rollers are used, although in alternative embodiments, any number of rollers may be used.

[0050] In addition to reducing the thickness of the welded seam, the cold forming process may also improve the surface finish and strengthen the material. After the cold forming process, the cylinder may also be subjected to heat treatment and polishing steps.

[0051] In one embodiment, the rollers 440 are spaced from the mandrel 420 by a distance equal to the desired thickness of the finished cylinder. Therefore, in such an embodiment, the thickness of the cylinder 410 (including the thickness of the welded seam) is reduced to the desired thickness with a single pass of the rollers 440. In an alternative embodiment, the rollers 440 are initially spaced apart by a distance greater than the desired thickness of the finished cylinder. In such an embodiment, after the first pass of the rollers 440, the rollers 440 are returned to their axial starting position, and the distance between the rollers 440 and the mandrel 420 is reduced. A second pass of the rollers is then performed. If the cylinder thickness is still greater than desired, the process can be repeated for as many passes as desired. In all embodiments, the rollers 440 may be arranged alternately both axially and radially.

[0052] If cylinder 410 has an angled weld (as shown in cylinder 300B) or a spiral weld (as shown in cylinder 300C), the direction of rotation of the roller can vary relative to the direction of the weld. For example, Figure 8A is a perspective view of the cylinder of Figure 6B, with the arrow indicating that the roller advances in a complementary direction to the weld. Alternatively, Figure 8B is a perspective view of the cylinder of Figure 6B, with the arrow indicating that the roller advances in a direction opposite to the weld.

[0053] The mechanical and fatigue properties of the cylinder 410 may be substantially different after the flow forming process due to the resulting microstructure. It is known that the microstructure within a material is directly linked to the mechanical and fatigue properties. By plastically deforming the material through cold working during the flow forming process, it is expected that an improved microstructure will be developed to not only relieve stress at the weld line, but also result in improved mechanical and fatigue properties within the final part.

[0054] Although the band layer and tread rubber layer are described in relation to a non-pneumatic tire, it should be understood that they may also be used in pneumatic tires, such as run-flat pneumatic tires.

[0055] To the extent that it is used in this specification or in the claims, the terms "includes" or "including" are intended to be inclusive, similar to the interpretation of the term "comprising" when used as a transitional phrase in a patent claim. Furthermore, to the extent that 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, to the extent that the terms "in" or "into" are used in this specification or in the claims, they 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 connecting via another component.

[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 improvements 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 illustrative examples shown and described. Accordingly, 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 making a non-pneumatic tire, said method comprising: providing an assembly having a lower ring, an upper ring coaxial with said lower ring, and a support structure extending from said lower ring to said upper ring; Providing a material sheet; forming the sheet of material into a cylinder such that a first edge of the sheet of material contacts a second edge of the sheet of material; welding the first edge to the second edge to form a seamed cylinder weld joint; cold forming the seamed cylinder to reduce the thickness of the weld joint; placing the seamed cylinder around the upper ring; providing a tread rubber around the seamed cylinder; The cold forming of the seamed cylinder comprises: placing the seamed cylinder on a mandrel having a spindle; rotating the mandrel and the cylinder in a first direction with the spindle; a plurality of rollers are engaged with the cylinder and rotated in a second direction opposite to the first direction; A method comprising:

2. The method of claim 1 , wherein cold forming the seamed cylinder further thins the wall of the seamed cylinder.

3. The method described in claim 1, wherein the second direction is a direction complementary to the weld joint.

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