JP2021030542A - Manufacturing method for non-pneumatic tire - Google Patents

Abstract

To provide a manufacturing method for a non-pneumatic tire capable of suppressing an occurrence of misalignment and air entry when a reinforcing structure is provided by a laminated band.SOLUTION: A manufacturing method for a non-pneumatic tire includes the steps of: manufacturing a coated core wire C70 in which the core wire is coated with elastomer; arranging a first array 71 formed by arranging the coated core wire C70 in a first direction in an annular shape along the outer circumference of the annular outer ring 1 of a support structure SS; circularly arranging a second array 72 formed by arranging the coated core wire C70 in a second direction along the outer circumference of the first array 71; heating and pressurizing a laminated band 6 including the first array 71 and the second array 72; and providing an annular tread rubber forming a ground plane on the outer circumference of the laminated band 6.SELECTED DRAWING: Figure 6

Description

The present invention relates to a method for manufacturing a non-pneumatic tire in which an annular reinforcing structure is provided on the outer ring of the support structure.

In recent years, various non-pneumatic tires have been proposed as substitutes for pneumatic tires. Such a non-pneumatic tire includes a support structure that supports a load from the vehicle, and the support structure includes an annular outer ring and an annular inner surface that is concentrically provided inside the outer ring in the tire radial direction. It has a ring and spokes connecting the outer ring and the inner ring. An annular tread rubber forming a ground contact surface is provided on the outer side of the outer ring in the tire radial direction. Further, a structure is known in which an annular reinforcing structure including a core wire is provided on the outer ring so as to increase the load bearing capacity (for example, Patent Document 1).

The present inventor has studied to form a laminated band by alternately stacking an array of core wires and an elastomer layer in the tire radial direction in order to further enhance the reinforcing effect, thereby forming a reinforcing structure. Since the support structure for a non-pneumatic tire is generally manufactured by a casting method, it is possible to provide a reinforcing structure by utilizing this process. That is, the laminated band is set in the mold for casting and molding the support structure, and the resin that is the base material of the support structure is poured into the mold, so that the laminated band that becomes the reinforcing structure is formed into an outer ring. Can be provided integrally with.

However, in the above manufacturing method, there is a concern that a problem may occur when the reinforcing structure is provided by the laminated band. Specifically, when the viscous resin flows while contacting the laminated band, the laminated band may be displaced in the mold, which may adversely affect the uniformity of the tire. Further, if the resin does not spread in the gaps between the core wires constituting the laminated band, air may enter due to residual air, which may be a starting point of failure such as separation, which may adversely affect the durability of the tire.

Japanese Patent Publication No. 2014-503394

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a non-pneumatic tire capable of suppressing misalignment and occurrence of air entry when a reinforcing structure is provided by a laminated band. There is.

In the method for producing a non-pneumatic tire of the present invention, a step of producing a coated core wire in which the core wire is coated with an elastomer and a first coating core wire are formed along the outer periphery of an annular outer ring of the support structure. A step of arranging the first array arranged in a direction in a ring shape and a second arrangement formed by arranging the coated core wires in the first direction or the second direction along the outer periphery of the first array. A step of arranging the bodies in an annular shape, a step of heating and pressurizing a laminated band including the first array and the second array, and providing an annular tread rubber forming a ground contact surface on the outer periphery of the laminated band. It has a process.

According to this method, the reinforcing structure is provided on the outer periphery of the outer ring by heating and pressurizing the laminated band containing the first array and the second array as described above. Each of the first array and the second array is an array of coated core wires in which the core wires are coated with an elastomer. Therefore, there is no concern that the laminated band will be misaligned, and there is no concern that the elastomer will not spread in the gaps between the core wires. Therefore, when the reinforcing structure is provided by the laminated band, it is possible to suppress the occurrence of misalignment and air entry.

In the step of producing the coated core wire, the elastomer is coated on a plurality of the core wires arranged in parallel to prepare a strip having a width dimension corresponding to the first array or the second array. It may be. As a result, the work of arranging the first array and / or the second array in an annular shape becomes easy, and the laminated band can be easily formed.

In the step of providing the tread rubber, an unvulcanized rubber layer may be arranged in an annular shape on the outer periphery of the laminated band after heating and pressurizing, and then the rubber layer may be heated and pressed for vulcanization. By heating and pressurizing the laminated band before providing the tread rubber, the misalignment of the laminated band can be suppressed more reliably.

The laminated band may be surrounded from the outside in the tire radial direction by an annular mold composed of a plurality of divided pieces divided in the tire circumferential direction, and the laminated band may be heated and pressed by the mold. As a result, the laminated band formed on the outer circumference of the outer ring can be easily heated and pressed.

The diameter of the mold may be gradually reduced while heating and pressurizing the laminated band with the mold. As a result, the air discharge property in the laminated band can be enhanced, and the occurrence of air entry can be suppressed more reliably.

Front view showing an example of a non-pneumatic tire according to the present invention. Tire meridian cross section of non-pneumatic tires Perspective view showing a part of a non-pneumatic tire Perspective view schematically showing the configuration of the laminated band Perspective view showing a cross section of a covered core wire Schematic diagram showing a process of arranging an array on the outer circumference of an outer ring Schematic diagram showing a process of heating and pressurizing a laminated band Perspective view schematically showing the structure of the laminated band in another embodiment.

An embodiment of the present invention will be described with reference to the drawings. First, an example of the configuration of the non-pneumatic tire will be described, and then a method of manufacturing the non-pneumatic tire will be described.

[Composition of non-pneumatic tires]
FIG. 1 is a front view showing an example of a non-pneumatic tire T, and is partially enlarged. FIG. 2 is a tire meridian cross-sectional view of the non-pneumatic tire T, and corresponds to the cross-sectional view taken along the line AA of FIG. FIG. 3 is a perspective view showing a part of the non-pneumatic tire shown in FIG. The non-pneumatic tire T includes a support structure SS that supports a load from the vehicle. The support structure SS includes an annular outer ring 1, an annular inner ring 2 concentrically provided on the tire radial inner RDi of the outer ring 1, and spokes 3 connecting the outer ring 1 and the inner ring 2. And have. A plurality of spokes 3 are independently provided on the tire circumferential direction CD.

It is preferable that the outer ring 1, the inner ring 2 and the spokes 3 are basically made of the same material. Thereby, when manufacturing the support structure SS, they can be easily integrally molded by using, for example, a casting molding method. In the present embodiment, the support structure SS is integrally molded with an elastic material, that is, the outer ring 1, the inner ring 2 and the plurality of spokes 3 are integrally molded.

In the present specification, the elastic material refers to a material having a tensile modulus of 100 MPa or less, which is obtained as a tensile stress at 10% elongation by a tensile test based on JIS K7312. From the viewpoint of imparting sufficient durability and appropriate rigidity to the support structure SS, the tensile modulus of the elastic material is preferably 5 to 100 MPa, more preferably 7 to 50 MPa. Examples of the elastic material used as the base material include thermoplastic elastomers, crosslinked rubbers, and other resins.

As the thermoplastic elastomer, for example, polyester elastomer, polyolefin elastomer, polyamide elastomer, polystyrene elastomer, polyvinyl chloride elastomer, and polyurethane elastomer are used. In addition to natural rubber, rubber materials constituting the crosslinked rubber include, for example, styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IIR), nitrile rubber (NBR), and hydrogenated nitrile rubber (hydrogenated). Synthetic rubbers such as NBR), chloroprene rubber (CR), ethylenepropylene rubber (EPDM), fluororubber, silicon rubber, acrylic rubber, and urethane rubber are used. Two or more of these rubber materials may be used in combination, if necessary.

As the other resin, a thermoplastic resin or a thermosetting resin is used. As the thermoplastic resin, for example, polyethylene resin, polystyrene resin, polyvinyl chloride resin and the like are used. As the thermosetting resin, for example, epoxy resin, phenol resin, polyurethane resin, silicon resin, polyimide resin, melamine resin and the like are used. From the viewpoint of moldability and processability, polyurethane resin is preferably used among the elastic materials described above. A foamed material may be used as the elastic material, and the above-mentioned thermoplastic elastomer, crosslinked rubber, or other foamed resin can be used.

The outer ring 1 is formed of an annular cylindrical body along the tire circumferential direction CD. From the viewpoint of improving the uniformity of the tire T, it is preferable that the thickness T1 of the outer ring 1 is constant. From the viewpoint of reducing the weight and improving the durability while sufficiently transmitting the force from the spokes 3, the thickness T1 is preferably 2 to 20%, more preferably 10 to 15% of the tire cross-sectional height TH. Assuming a substitute for a general pneumatic tire for automobiles, the inner diameter of the outer ring 1 is preferably 420 to 750 mm, more preferably 470 to 680 mm. Similarly, when a substitute for an automobile tire is assumed, the width W1 of the outer ring 1 in the tire width direction WD is preferably 100 to 300 mm, more preferably 120 to 250 mm.

An annular tread rubber 4 forming a ground contact surface is provided on the outer RDo in the tire radial direction of the outer ring 1. As the rubber composition forming the tread rubber 4, a rubber composition similar to the tread rubber provided in the conventional pneumatic tire is preferably used. Various tread patterns can be provided on the outer peripheral surface of the tread rubber 4 in order to improve the running performance on a wet road surface.

The inner ring 2 is formed of an annular cylindrical body along the tire circumferential direction CD. From the viewpoint of improving the uniformity of the tire T, it is preferable that the thickness T2 of the inner ring 2 is constant. From the viewpoint of reducing the weight and improving the durability while sufficiently transmitting the force from the spokes 3, the thickness T2 is preferably 2 to 10% of the tire cross-sectional height TH, and more preferably 3 to 9%. Assuming a substitute for a general pneumatic tire for automobiles, the inner diameter of the inner ring 2 is preferably 250 to 500 mm, more preferably 320 to 440 mm. Similarly, when a substitute for an automobile tire is assumed, the width W2 of the inner ring 2 in the tire width direction WD is preferably 100 to 300 mm, more preferably 120 to 250 mm.

A member (not shown) for matching with an axle or a rim can be provided on the inner RDi in the tire radial direction of the inner ring 2. The inner peripheral surface of the inner ring 2 may be provided with irregularities for maintaining the fitability of the fitting member.

Each of the plurality of spokes 3 extends in the tire radial direction RD to connect the outer ring 1 and the inner ring 2. The tire radial outer ends of the spokes 3 are joined to the inner peripheral surface of the outer ring 1, and the tire radial inner ends of the spokes 3 are joined to the outer peripheral surface of the inner ring 2. From the viewpoint of improving the uniformity of the tire T, it is preferable that the distance G between the spokes 3 in the tire circumferential direction CD is constant. From the viewpoint of making the ground pressure uniform and suppressing the increase of noise, the interval G is preferably 10 mm or less, more preferably 5 mm or less.

In the present embodiment, a plurality of spokes 3 extend from one side WD1 in the tire width direction of the outer ring 1 toward the other side WD2 in the tire width direction of the inner ring 2 and from the other side WD2 of the outer ring 1. An example including a second spoke 32 extending toward one side WD1 of the inner ring 2 is shown. The first spokes 31 and the second spokes 32 that are adjacent to each other are arranged in an X shape when viewed from the tire circumferential direction CD. The plurality of spokes 3 are composed of first spokes 31 and second spokes 32 that are alternately arranged along the tire circumferential direction CD. The spoke shape of the non-pneumatic tire manufactured by the present invention is not particularly limited.

From the viewpoint of reducing the weight, improving the power transmission, and improving the durability while sufficiently supporting the load from the vehicle, the number of spokes 3 is preferably 50 to 300, more preferably 100 to 200. In the present embodiment, the plurality of spokes 3 are composed of 50 first spokes 31 and 50 second spokes 32 (see FIG. 1). The tensile modulus of the spokes 3 is preferably 5 to 180,000 MPa, preferably 7 to 50,000 MPa, from the viewpoint of reducing weight, improving durability, and improving lateral rigidity while sufficiently transmitting the force from the outer ring 1 and the inner ring 2. More preferred. The tensile modulus of the spokes 3 may be increased by using a fiber reinforced material in which the elastic material is reinforced with fibers.

The first spoke 31 is formed in the shape of a long plate extending in the tire radial direction RD and the tire width direction WD. The first spoke 31 has a plate thickness t along the tire circumferential direction CD and a plate width w larger than the plate thickness t. The plate thickness t may be constant along the long direction PL, but it is preferable that the plate thickness t gradually increases toward the outer RDo in the tire radial direction as shown in FIG. Even in such a case, the plate thickness t is smaller than the plate width w at the joint between the inner peripheral surface of the outer ring 1 and the outer end of each of the spokes 3 in the tire radial direction. In the present embodiment, the plate thickness direction PT coincides with the tire circumferential direction CD, but the present invention is not limited to this.

From the viewpoint of reducing the weight and improving the durability while sufficiently transmitting the force from the outer ring 1 and the inner ring 2, the plate thickness t is preferably 8 to 30 mm, more preferably 10 to 25 mm. From the same viewpoint, the plate width w is preferably 5 to 25 mm, more preferably 10 to 20 mm. Further, from the viewpoint of improving the durability and reducing the dispersion of the ground pressure, the plate width w is preferably 110% or more, more preferably 115% or more of the plate thickness t. Since the second spoke 32 is formed in the same manner as the first spoke 31 except that the second spoke 32 is arranged symmetrically with respect to the tire equatorial plane TE, duplicate description will be omitted.

The first spoke 31 is composed of an inner end portion 3a, a central portion 3b, and an outer end portion 3c. The central portion 3b includes a range X centered on the height center 31c of the first spoke 31 in the tire radial direction RD, and this range X is 10 to 90% of the height h of the first spoke 31. The plate width wb of the central portion 3b in the tire width direction WD is constant, while the plate width wc of the outer end portion 3c gradually increases toward the outer RDo in the tire radial direction. Similarly, the plate width wa of the inner end portion 3a gradually increases toward the inner RDi in the tire radial direction. As a result, stress concentration at the joint between the outer ring 1 and the inner ring 2 can be reduced and durability can be improved.

In this non-pneumatic tire T, a reinforcing structure 5 is provided on the outer ring 1 for the purpose of increasing the load bearing capacity. The reinforcing structure 5 is formed in an annular shape along the tire circumferential direction CD. From the viewpoint of ensuring the reinforcing effect, the width W5 of the reinforcing structure 5 (see FIG. 2) is preferably 50% or more, more preferably 80% or more of the width W1 of the outer ring 1. In the present embodiment, the reinforcing structure 5 is provided on the outer periphery of the outer ring 1, and the tread rubber 4 is provided on the outer periphery of the reinforcing structure 5. However, the present invention is not limited to this, and for example, a structure in which the reinforcing structure 5 is embedded inside the outer ring 1 may be used.

The reinforcing structure 5 is composed of a laminated band 6 as shown in FIG. The laminated band 6 is formed by alternately stacking an array 7 of core wires 70 and a resin layer 8 which is an elastomer layer in the tire radial direction RD. The laminated band 6 includes a plurality of (that is, two or more) arrays 7. Each of the arrays 7 is composed of a plurality of core wires 70 arranged in parallel with each other. The material of the core wire 70 is not particularly limited, but for example, an organic fiber cord such as rayon, nylon, polyester, or aramid, or a metal fiber cord such as steel is preferably used. The resin layer 8 is preferably formed of the same material as the base material of the outer ring 1, but may be made of a different material.

In the present embodiment, the laminated band 6 includes three arrays 7 of the first array 71, the second array 72, and the third array 73. The first array 71 and the third array 73 are configured by arranging the core wires 70 extending in the tire circumferential direction CD in the tire width direction WD, respectively. In the first array 71 and the third array 73, the inclination angle of the core wire 70 with respect to the tire circumferential direction CD is substantially 0 degree. Further, the second array 72 is configured by arranging the core wires 70 extending in the tire width direction WD in the tire circumferential direction CD. In the second array 72, the inclination angle of the core wire 70 with respect to the tire circumferential direction CD is substantially 90 degrees.

[Manufacturing method of non-pneumatic tires]
Next, a method for manufacturing the non-pneumatic tire T will be described. This manufacturing method includes a step of producing a coated core wire in which the core wire 70 is coated with an elastomer (coating step), a step of arranging the first array 71 on the outer periphery of the outer ring 1 (first arrangement step), and a step of arranging the first array 71 on the outer periphery of the outer ring 1. A step of arranging the second arrangement 72 on the outer periphery of the first arrangement 71 (second arrangement step) and a step of heating and pressurizing the laminated band 6 including the first arrangement 71 and the second arrangement 72 (heating). A pressurizing step) and a step of providing the tread rubber 4 on the outer periphery of the laminated band 6 (tread forming step) are provided.

In the coating step of the present embodiment, the plurality of parallel core wires 70 are coated with the resin 80 which is an elastomer to prepare a strip-shaped product composed of the coated core wires C70 as shown in FIG. The surface of this strip is slightly wavy, but may be flat. Such a coated core wire C70 can be produced by using a conventionally known calendar roll, but the present invention is not limited to this, and an extruder may be used to produce the coated core wire C70. However, it is more efficient to use a calendar roll in order to produce a strip having a width dimension corresponding to the first array 71 (and the third array 73) in which the core wires 70 are arranged in the tire width direction WD. Is.

The support structure SS shown in FIG. 6 (A) is manufactured in advance by using a casting molding method or the like. In the first arrangement step, as shown in FIG. 6B, the covering core wire C70 is arranged in the tire width direction WD (corresponding to the first direction) along the outer circumference of the annular outer ring 1 of the support structure SS. The first array 71 formed by the above is arranged in a ring shape. Further, in the second arrangement step, as shown in FIG. 6C, the coated core wire C70 is arranged along the outer circumference of the first arrangement 71 in the tire circumferential direction CD (corresponding to the second direction). The two arrays 72 are arranged in a ring shape. Further, in the present embodiment, as shown in FIG. 6D, the third array 73 formed by arranging the coated core wires C70 in the tire width direction WD is arranged in an annular shape along the outer circumference of the second array 72. (Third arrangement step).

From the viewpoint of simplifying the first arrangement step, a band-shaped object having a width dimension corresponding to the first array body 71 is prepared, and the band-shaped object is wound around the outer circumference of the outer ring 1 to arrange the first array body 71. It is preferable to do so. The same applies to the second and third arrangement steps. However, in the second arrangement step, a strip-shaped object in which the core wire 70 is inclined at an angle of 90 degrees with respect to the tire circumferential direction CD is used. In such a strip, the coated core wire C70 is cut to a predetermined length (a length corresponding to the width dimension of the second array 72), and the strip-shaped coated core wire C70 obtained thereby is cut into a CD in the tire circumferential direction. It is produced by sequentially joining in (arrangement direction of the coated core wire C70).

In the heating and pressurizing step, the laminated band 6 including the first array 71 and the second array 72 (and the third array 73 in the present embodiment) is heated and pressurized. As a result, the resin 80 covering the core wire 70 is melted, and the plurality of stacked arrays 7 are fused to each other. At that time, unlike the casting molding method, it is not necessary to evenly flow the resin, so that there is no concern that the laminated band 6 will be misaligned. Further, since each of the core wires 70 is already surrounded by the resin 80, the resin 80 can be sufficiently distributed. Therefore, the laminated band 6 suppresses the occurrence of misalignment and air entry when the reinforcing structure 5 is provided. The resin layer 8 (see FIG. 4) of the laminated band 6 is formed of the resin 80 coated with the core wire 70.

In the heating and pressurizing step, the laminated band 6 may be surrounded from the outside in the tire radial direction by an annular mold 9 as shown in FIG. 7, and the laminated band 6 may be heated and pressurized by the mold 9. The mold 9 is composed of a plurality of (four in the example of FIG. 7) divided pieces 91 divided into CDs in the tire circumferential direction, and each of them can be opened and closed by moving in the tire radial direction. The mold 9 is heated to a required temperature by a heating means (not shown) and pressed against the laminated band 6. The diameter of the mold 9 may be gradually reduced while heating and pressurizing the laminated band 6 by the mold 9, whereby the resin 80 can be pushed in while being melted, and the occurrence of air entry can be more reliably suppressed.

In the tread forming step, an annular tread rubber 4 forming a ground plane is provided on the outer periphery of the laminated band 6. In the present embodiment, the tread rubber 4 is provided by arranging an unvulcanized rubber layer on the outer circumference of the laminated band 6 after heating and pressurizing in an annular shape, and then heating and pressurizing the rubber layer to perform vulcanization. Be done. Since the laminated bands 6 are heated and pressed before the tread rubber 4 is provided to fuse the plurality of arrays 7 to each other, the misalignment of the laminated bands 6 can be suppressed more reliably.

The non-pneumatic tire T manufactured through the above steps includes a reinforcing structure 5 composed of a laminated band 6. As described above, since the occurrence of misalignment of the laminated band 6 during manufacturing is suppressed, there is little concern that the uniformity of the tire will be impaired. Further, by suppressing the generation of air entering in the laminated band 6, it is possible to obtain a state in which the resin 80 is evenly fixed around the core wire 70. Therefore, there is less concern that the durability of the tire will be impaired because there will be no location that is likely to be the starting point of failure such as separation.

In the plurality of arrays 7 included in the laminated band 6, the arrangement direction of the coated core wires C70 is not particularly limited. In the present embodiment, the arrangement directions of the coated core wires C70 are different between the first array 71 and the second array 72, but they may be the same. Therefore, the arrangement direction of the covered core wires C70 constituting the second arrangement 72 may be the tire width direction WD (corresponding to the first direction). As shown in FIG. 8, it is also possible to arrange the coated core wires C70 diagonally with respect to the tire circumferential direction CD. In the example of FIG. 8, the coated core wires C70 are arranged in opposite directions between the first array 71 and the second array 72.

In the present embodiment, an example in which a strip of the coated core wire C70 having a predetermined width dimension is wound around the first array 71 is arranged, but the present invention is not limited to this. For example, using an extruder, one or more core wires coated with an elastomer are continuously extruded, and the coated core wires are spirally wound along the tire circumferential direction. As a result, an array in which the covered core wire extends in the tire circumferential direction (first array 71 or third array 73 in the present embodiment) may be formed.

In the present embodiment, the example in which the elastomer coated on the core wire 70 is the resin 80 is shown, but the present invention is not limited to this, and for example, rubber may be used. In that case, the elastomer layer contained in the laminated band is formed of rubber. Further, when the elastomer is rubber, the unvulcanized rubber layer may be arranged in an annular shape on the laminated band before heating and pressurizing. Thereby, in the step of heating and pressurizing the laminated band, the rubber layer to be the tread rubber can be vulcanized. That is, heating and pressurizing the laminated band and vulcanization in the tread forming step can be performed at the same time.

The present invention is not limited to the above-described embodiment, and various improvements and changes can be made without departing from the spirit of the present invention.

1 Outer ring 2 Inner ring 3 Spokes 4 Tread rubber 5 Reinforcing structure 6 Laminated band 7 Array 8 Resin layer (example of elastomer layer)
9 Mold 70 Core wire 71 First array 72 Second array 73 Third array 80 Resin (an example of elastomer)
C70 covered core wire SS support structure T non-pneumatic tire

Claims (5)

The process of producing a coated core wire in which the core wire is coated with an elastomer,
A step of arranging the first array formed by arranging the coated core wires in the first direction in an annular shape along the outer circumference of the annular outer ring of the support structure.
A step of arranging the second array formed by arranging the coated core wires in the first direction or the second direction in an annular shape along the outer circumference of the first array.
A step of heating and pressurizing a laminated band containing the first array and the second array,
A method for manufacturing a non-pneumatic tire, comprising a step of providing an annular tread rubber forming a ground contact surface on the outer periphery of the laminated band. In the step of producing the coated core wire, the elastomer is coated on a plurality of the core wires arranged in parallel to prepare a strip having a width dimension corresponding to the first array or the second array. The method for manufacturing a non-pneumatic tire according to claim 1. In the step of providing the tread rubber, after heating and pressurizing, an unvulcanized rubber layer is arranged in an annular shape on the outer periphery of the laminated band, and then the rubber layer is heated and pressed to perform vulcanization. 2. The method for manufacturing a non-pneumatic tire according to 2. Any one of claims 1 to 3, wherein the laminated band is surrounded from the outside in the tire radial direction by an annular mold composed of a plurality of divided pieces divided in the tire circumferential direction, and the laminated band is heated and pressurized by the mold. The method for manufacturing a non-pneumatic tire according to. The method for manufacturing a non-pneumatic tire according to claim 4, wherein the laminated band is heated and pressed by the mold to gradually reduce the diameter of the mold.

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