Manufacturing method for non-pneumatic tires

Abstract

To provide a method for manufacturing non-pneumatic tires that can reduce defects in the bonding of the tread rubber. [Solution] A method for manufacturing a non-pneumatic tire 1 comprising a support structure 10 having an outer annular portion 30 and a tread 50 fixed to the outer annular portion 30, comprising the steps of: temporarily bonding the vulcanized tread rubber 50 to the outer peripheral surface 30a of the outer annular portion 30 of the support structure 10 (S1); covering the vulcanized tread rubber 50 with an envelope 61 (S2); arranging the support structure 10, the vulcanized tread rubber 50 and the envelope 61 in a pressurized vessel 71 (S3); forming a sealed space 62 between the envelope 61 and the vulcanized tread rubber 50 (S4); and vulcanizing and bonding the vulcanized tread rubber 50 to the outer peripheral surface 30a by pressurizing and heating the pressurized vessel 71 (S5).

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a non-pneumatic tire.

Background Art

[0002] Conventionally, a non-pneumatic tire is known that includes a support structure containing resin for supporting the load from a vehicle, and a tread rubber located radially outside the support structure in the tire diameter direction and extending along the tire circumferential direction (see, for example, Patent Document 1).

[0003] On the other hand, in a pneumatic tire, by disposing new rubber or recycled tire raw materials on the worn tread rubber portion, it is reused as a recycled tire again. A precure method is known in the method for manufacturing a recycled tire, in which a vulcanized precure tread is attached to the tire and vulcanized in a pressure cooker. Here, in the precure method, a bag-like body such as a rubber tube called an envelope is covered on the tire and placed in a pressure cooker for vulcanization. (See, for example, Patent Document 2)

[0004] Generally, as a method for manufacturing a non-pneumatic tire, in the step of providing a tread of the tire, an external force is applied to pressurize the adhesion surface of the tread rubber and the support structure, thereby developing the adhesive force between the support structure and the tread rubber.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0007] However, in the manufacturing method of joining treads of non-pneumatic tires using the pre-cure method, non-pneumatic tires do not have a component equivalent to the bead in pneumatic tires. Therefore, it is not possible to attach the envelope and tire fixing attachment commonly used in pneumatic tires, and it is difficult to isolate the inside and outside of the envelope after it has been covered. If a non-pneumatic tire is placed in a pressurized oven without isolating the inside and outside of the envelope that has been covered, no pressure difference will be created between the inside and outside of the tire covering material. As a result, the bonding surface may not be sufficiently pressurized, which may lead to bonding failure.

[0008] The present invention aims to provide a method for manufacturing a non-pneumatic tire that can reduce bonding defects in the tread rubber. [Means for solving the problem]

[0009] A method for manufacturing a non-pneumatic tire according to one aspect of the present invention is a method for manufacturing a non-pneumatic tire having a support structure having an outer annular portion and a tread fixed to the outer annular portion, A process of temporarily bonding the vulcanized tread rubber to the outer surface of the outer ring portion of the support structure, A step of covering the vulcanized tread rubber with an envelope, A step of forming a sealed space between the envelope and the vulcanized tread rubber, The process of placing the support structure, the vulcanized tread rubber, and the envelope in a pressurized vessel, The process involves pressurizing and heating the inside of the pressurized oven to vulcanize and bond the vulcanized tread rubber to the outer surface, It is equipped with. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for manufacturing a non-pneumatic tire that can reduce bonding defects of the tread rubber. [Brief explanation of the drawing]

[0011] [Figure 1] This is a side view showing a non-pneumatic tire according to one embodiment of the present invention. [Figure 2] This is a cross-sectional view of the outer annular portion along line II-II in Figure 1. [Figure 3] This is a cross-sectional view taken along line II-II in Figure 1. [Figure 4] Figure 3 is a perspective view of a portion of a non-pneumatic tire, seen from an oblique angle. [Figure 5] This is a flowchart showing the steps involved in the vulcanization and bonding method for tread rubber. [Figure 6] This is a cross-sectional view of a non-pneumatic tire with an envelope attached. [Figure 7] This is a magnified section of Figure 6. [Figure 8] This is a schematic diagram of a pressure cooker and jig. [Figure 9] This is a magnified view of a portion of Figure 8. [Modes for carrying out the invention]

[0012] (Basic structure of non-pneumatic tires) A non-pneumatic tire 1 of one embodiment of the present invention will be described using Figures 1 to 4. Figure 1 is a side view showing a non-pneumatic tire according to one embodiment of the present invention. Figure 2 is a cross-sectional view taken along line II-II of the outer annular portion of Figure 1. Figure 3 is a cross-sectional view taken along line II-II of Figure 1. Figure 4 is a partial perspective view of the non-pneumatic tire, taken from an oblique angle of the portion shown in Figure 3.

[0013] The non-pneumatic tire 1 includes a support structure 10 and a tread 50. Here, the support structure 10 supports the load from the vehicle. Also, the tread 50 is located outside the support structure 10 in the tire radial direction X and extends along the tire circumferential direction C. Further, the support structure 10 includes an inner annular portion 20, an outer annular portion 30 disposed coaxially with the inner annular portion 20 outside the inner annular portion 20 in the tire radial direction X, and a plurality of spokes 40 that connect the inner annular portion 20 and the outer annular portion 30 and are arranged along the tire circumferential direction C.

[0014] As shown in FIG. 2, in the outer annular portion 30, a reinforcing layer 32 is embedded in an elastic body 31. Here, the reinforcing layer 32 extends along the tire circumferential direction C and is embedded over the entire circumference of the outer annular portion 30 and over the entire region in the tire width direction Y.

[0015] (Detailed Structure of Non-Pneumatic Tire) FIG. 1 is a side view of the non-pneumatic tire 1 viewed from a direction parallel to the tire rotation axis (tire meridian), that is, along the front-back direction of the paper surface in FIG. 1. The non-pneumatic tire 1 shown in FIG. 1 is in an unloaded state.

[0016] In FIGS. 1 and 4, C indicates the tire circumferential direction. In FIGS. 1 to 4, X indicates the tire radial direction. In FIGS. 2 to 4, Y indicates the tire width direction. In FIG. 1, the tire width direction Y is the front-back direction of the paper surface. In FIG. 3, E indicates the tire equatorial plane. In FIG. 3, the tire circumferential direction C is the front-back direction of the paper surface.

[0017] The tire circumferential direction C is the direction around the tire rotation axis and is the same direction as the direction in which the non-pneumatic tire 1 rotates. The tire radial direction X is the direction perpendicular to the tire rotation axis. The tire width direction Y is the direction parallel to the tire rotation axis. In FIGS. 2 to 4, one side of the tire width direction Y is shown as Y1, and the other side of the tire width direction Y is shown as Y2. The tire equatorial plane E shown in FIG. 3 is a plane perpendicular to the tire rotation axis and is located at the center of the tire width direction Y.

[0018] The inner annular portion 20 is an annular part along the tire circumferential direction C that constitutes the inner circumference of the non-pneumatic tire 1. The thickness and width of the inner annular portion 20 are set to be constant in order to improve uniformity. A tire wheel (not shown) is placed in the space on the inner circumference side of the inner annular portion 20. The inner circumference of the inner annular portion 20 is fitted and mounted onto the outer circumference of the rim of the tire wheel. With the inner annular portion 20 mounted on the rim, the non-pneumatic tire 1 is mounted on the tire wheel.

[0019] The inner annular portion 20 transmits the rotation of the tire wheel to the spokes 40 and the outer annular portion 30.

[0020] The outer annular portion 30 is an annular part along the tire circumferential direction C that constitutes the outer circumference of the non-pneumatic tire 1. The outer annular portion 30 is arranged concentrically with the inner annular portion 20 on the outer circumference side of the inner annular portion 20.

[0021] The outer annular portion 30 transmits the rotation of the inner annular portion 20 and the spokes 40 to the road surface via the tread 50.

[0022] Multiple spokes 40 connect the inner annular portion 20 and the outer annular portion 30. The inner annular portion 20 and the outer annular portion 30, connected by the multiple spokes 40, are arranged concentrically with respect to each other. Each of the multiple spokes 40 is arranged independently along the tire circumferential direction C. As shown in Figure 1, when the non-pneumatic tire 1 is unloaded, the multiple spokes 40 extend linearly in the radial direction, approximately parallel to the tire radial direction X, when viewed from the side.

[0023] As shown in Figures 3 and 4, the spokes 40 of this embodiment include a plurality of first spokes 41 and a plurality of second spokes 42. The extending direction of both the first spokes 41 and the second spokes 42 is not parallel to the tire radial direction X when viewed along the tire circumferential direction C. The first spokes 41 are inclined toward one side in the tire axial direction, i.e., the tire width direction Y. The second spokes 42 are inclined toward the opposite side from the first spokes 41. The first spokes 41 and the second spokes 42 are arranged alternately in the tire circumferential direction C.

[0024] More specifically, as shown in Figures 3 and 4, the first spoke 41 extends inclined from the Y1 side, which is one side of the outer annular portion 30 in the tire width direction Y, toward the Y2 side, which is the other side of the inner annular portion 20 in the tire width direction Y. The second spoke 42 extends inclined from the Y2 side, which is the other side of the outer annular portion 30 in the tire width direction Y, toward the Y1 side, which is one side of the inner annular portion 20 in the tire width direction Y.

[0025] The inclination angles of the first spoke 41 and the second spoke 42 are the same. Therefore, when viewed from a direction along the tire circumferential direction C, the first spoke 41 and the second spoke 42 adjacent to each other in the tire circumferential direction C are arranged in a roughly X shape.

[0026] The tread 50 is provided on the outer circumferential surface of the outer annular portion 30 and constitutes the outermost periphery of the non-pneumatic tire 1. The tread 50 has a tread surface 51 on its outer circumferential surface that contacts the road surface. The tread surface 51 of the tread 50 is provided with a tread pattern formed by multiple grooves and flat areas, similar to conventional pneumatic tires.

[0027] (Manufacturing method for non-pneumatic tires) As a method for manufacturing a non-pneumatic tire 1, a vulcanization bonding method for a non-pneumatic tire, in which a vulcanized tread rubber 50a is fixed to a support structure 10, will be described.

[0028] The method for manufacturing a non-pneumatic tire 1 involves first preparing a cured support structure 10 and a vulcanized tread rubber 50a.

[0029] The method for manufacturing a non-pneumatic tire further comprises steps S1 to S5, as shown in Figure 5. Figure 5 is a flowchart of the steps for the vulcanization and bonding method of tread rubber. Each step can be omitted or replaced as needed. Multiple steps may be performed simultaneously, or some or all of them may be performed in overlapping order.

[0030] (S1) A step of temporarily bonding the vulcanized tread rubber 50a to the outer peripheral surface 30a of the outer annular portion 30 of the support structure 10. The vulcanized tread rubber is attached to the outer surface 30a of the support structure 10. In this case, as shown in Figure 7, the outer surface 30a is laminated in the following order: vulcanizing adhesive 63, unvulcanized rubber 64, and rubber glue 65. Figure 6 is a cross-sectional view of a non-pneumatic tire with an envelope attached. Figure 7 is a partially enlarged view of Figure 6.

[0031] The vulcanized tread rubber 50a is not particularly limited, but may include, for example, natural rubber and carbon black, and may further contain sulfur, silica, etc. Here, the vulcanized tread rubber 50a may contain synthetic rubber such as polyisoprene rubber or styrene-butadiene rubber together with natural rubber, or in place of natural rubber.

[0032] The vulcanizing adhesive 63 is an adhesive that hardens in a subsequent vulcanization process, and may contain a rubber component blended with a vulcanization accelerator and an acid acceptor. For example, the vulcanizing adhesive 63 may consist of a polymer material, an organic material, and a filler, dispersed in an organic solvent system such as xylene. Halogen-based polymers can be used as the polymer material and organic material. Carbon black, silica, etc. can be used as the filler.

[0033] The unvulcanized rubber 64 is formed in a sheet shape and is vulcanized in a subsequent vulcanization process. The unvulcanized rubber 64 may be made of the same material as the vulcanized tread rubber 50a, or it may be made of a different material.

[0034] The rubber adhesive 65 is a temporary fixing means and is prepared by dissolving a kneaded rubber composition in an organic solvent. Examples of organic solvents include various volatile organic solvents that dissolve rubber, such as rubber volatile oil, toluene, and xylene. Preferably, a solution of butyl rubber in an organic solvent such as toluene can be used as the rubber adhesive 65.

[0035] (S2) Process of covering the vulcanized tread rubber 50a with the envelope 61. As shown in Figures 6 and 7, the envelope 61 is a bag-like structure. The envelope 61 is formed in a cylindrical shape when viewed from a line of sight parallel to the tire axis and has an opening facing inward in the radial direction of the tire. The envelope 61 covers only the vulcanized tread rubber 50a and the outer annular portion 30 of the support structure 10. In other words, the envelope 61 does not cover the inner annular portion 20. The material of the envelope 61 is, for example, rubber.

[0036] (S3) A step to form a sealed space 62 between the envelope 61 and the vulcanized tread rubber 50a. First, the support structure 10, the vulcanized tread rubber 50a, and the envelope 61 are placed in the jig 72 (Figure 8). Figure 8 is a schematic diagram of the pressurized vessel and the jig.

[0037] The jig 72 mainly comprises a first member 73, a second member 74, a third member 75, and a fourth member 76.

[0038] The first member 73 has a cylindrical portion 73A and a flat, annular portion 73B extending radially outward from one end of the cylindrical portion 73A. The second member 74 is a flat, annular member. The second member 74 has the same shape as the annular portion 73B and is positioned on the opposite side of the cylindrical portion 73A from the annular portion 73B. The support structure 10, the vulcanized tread rubber 50a, and the envelope 61 are positioned radially outward of the cylindrical portion 73A and between the annular portion 73B and the second member 74. The outer peripheral portions of the annular portion 73B and the second member 74 are positioned close to the axial annular plane 30b of the outer annular portion 30 of the support structure 10.

[0039] The interior of the jig 72 has a first internal space 82 on the inner circumference side of the cylindrical portion 73A of the first member 73, and a second internal space 83 (inner circumference space) on the outer circumference side of the cylindrical portion 73A of the first member 73. The first internal space 82 is cylindrical. The second internal space 83 is cylindrical. The support structure 10 is placed inside the second internal space 83.

[0040] The third member 75 and the fourth member 76 are pressing members for pressing the envelope 61 from the outside in the tire axial direction. The third member 75 and the fourth member 76 are disc-shaped members. The third member 75 and the fourth member 76 can be moved away from or towards each other along the tire axial direction by the air cylinder 91. The clamping force of the fixture is, for example, 0.8 MPa.

[0041] Using the jig 72, a portion of the envelope 61 is pressed against the axial annular plane 30b of the outer annular portion 30 of the support structure 10. Specifically, the end portion 61a of the envelope 61 is clamped against the axial annular plane 30b of the outer annular portion 30 using the jig 72.

[0042] As shown in Figures 8 and 9, a pair of sealing members 84 are positioned between the end portion 61a of the envelope 61 and the third member 75 and the fourth member 76. Figure 9 is a partially enlarged view of Figure 8.

[0043] The sealing member 84 is, for example, a rubber sheet. The sealing member 84 may also be a silicone packing. The pair of sealing members 84 are pressed against the third member 75 and the fourth member 76 to seal the space between the envelope 61 and the support structure 10.

[0044] As a result of the above, a sealed space 62 is formed between the envelope 61 and the vulcanized tread rubber 50a.

[0045] (S4) A step of placing the support structure 10, the vulcanized tread rubber 50a, and the envelope 61 into the pressurized vessel 71.

[0046] As shown in Figure 8, the jig 72 and the contents to be stored are placed inside the pressurized vessel 71.

[0047] The pressurized vessel 71, also known as an autoclave, has a box-shaped, sealed enclosure 71a, as shown in Figure 8, and can create a high-temperature, high-pressure environment inside. In other words, the pressurized vessel 71 has a heating device that uses steam, hot air, or electric heating, and a control device for adjusting the temperature and pressure, although not shown in the figure. In this state, the area inside the pressurized vessel 71 and outside the jig 72 is considered the external space 81.

[0048] As shown in Figure 8, in the state in which the envelope 61 is held by the third member 75 and the fourth member 76, the jig 72 is provided with external communication parts 751, 761, and 73A1 so that the second internal space 83 on the inner side of the outer annular portion 30 of the support structure 10 in the tire radial direction is not independent from the external space 81 of the jig 72. The communication part 751 is formed on the third member 75, and the communication part 761 is formed on the fourth member 76. As a result, the external space 81 and the first internal space 82 are in communication. The communication part 73A1 is formed on the cylindrical portion 73A of the first member 73. As a result, the first internal space 82 and the second internal space 83 are in communication. The spoke 40 and its surrounding area are under pressure. The dimensions of the communication part 73A1 are, for example, 20 mm × 55 mm × 4 locations on the circumference.

[0049] As a result of the above, the second internal space 83 and the external space 81 are connected by the connecting parts 751, 761, and 73A1, so that the second internal space 83 and the external space 81 are in the same pressurized environment.

[0050] (S5) A process of cold-vulcanizing and bonding the vulcanized tread rubber 50a to the outer peripheral surface 30a of the outer annular portion 30 of the support structure 10 by pressurizing and heating the inside of the pressurized oven 71. The support structure 10 and the vulcanized tread rubber 50a are vulcanized and bonded by heating and pressurizing using a pressure vessel 71. Specifically, the support structure 10 and the vulcanized tread rubber 50a are joined by vulcanizing the unvulcanized rubber 64.

[0051] The pressure (pressure inside the pressurized oven 71) when vulcanizing and bonding the support structure 10 and the vulcanized tread rubber 50a is preferably 0.6 MPa or higher.

[0052] The vulcanization temperature (temperature inside the pressurized vessel 71) is not particularly limited, but is, for example, 110°C to 120°C.

[0053] At this time, the inside and outside of the envelope 61 are separated at the end of the outer annular portion 30, that is, the spaces inside and outside the envelope 61 are separated from each other. As a result, the sealed space 62 under normal pressure is pressurized from both sides, so when vulcanization is performed in the pressurized vessel 71, the vulcanized tread rubber 50a is strongly pressed against the outer peripheral surface 30a of the outer annular portion 30 due to the pressure difference. As a result, bonding defects of the vulcanized tread rubber 50a can be reduced.

[0054] (Aspects of this embodiment) <1> A method for manufacturing a non-pneumatic tire 1 is a method for manufacturing a non-pneumatic tire 1 having a support structure 10 having an outer annular portion 30 and a tread 50 fixed to the outer annular portion 30, Step (S1) involves temporarily bonding the vulcanized tread rubber 50a to the outer peripheral surface 30a of the outer annular portion 30 of the support structure 10, The process of covering the vulcanized tread rubber 50a with the envelope 61 (S2), The process (S3) involves forming a sealed space 62 between the envelope 61 and the vulcanized tread rubber 50a, Step (S4) involves placing the support structure 10, the vulcanized tread rubber 50a, and the envelope 61 into the pressurized vessel 71, The process (S5) involves pressurizing and heating the inside of the pressurized oven 71 to vulcanize and bond the vulcanized tread rubber 50a to the outer surface 30a, It is equipped with.

[0055] <2> <1> In the method for manufacturing the non-pneumatic tire 1 described above, the step of forming a sealed space 62 (S2) includes the step of pressing a part of the envelope 61 against the axial annular plane 30b of the outer annular portion 30 of the support structure 10 using a jig 72.

[0056] <3> <2> In the method for manufacturing a non-pneumatic tire described above, the step of pressing a portion of the envelope 61 against the axial annular plane 30b of the outer annular portion 30 of the support structure 10 includes the step of using a jig 72 to clamp the end portion 61a of the envelope 61 against the axial annular plane 30b of the outer annular portion 30 of the support structure 10.

[0057] <4> <2> or <3> In the method for manufacturing a non-pneumatic tire described above, the jig 72 has a communication portion 73A1 that connects an external space 81 located in the pressurized vessel 71 and outside the jig 72 with a second internal space 83 located inside the jig 72 on the inner circumference side of the outer annular portion 30 of the support structure 10.

[0058] (Other embodiments) Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. In particular, the multiple embodiments and modifications described herein can be arbitrarily combined as needed.

[0059] In the above embodiment, the pair of sealing members 84 are positioned between the envelope 61 and the third member 75 and the fourth member 76, which act as pressing members. However, the position of the sealing members is not particularly limited. The sealing members may be positioned between the envelope 61 and the outer annular portion 30.

[0060] In the above embodiment, the third member 75 and the fourth member 76, which serve as pressing members, are configured to be movable by an air cylinder 91. However, the driving means is not limited to an air cylinder and can be changed in various ways. [Explanation of Symbols]

[0061] 1: Non-pneumatic tires 10:Support structure 30:Outer annular part 30a: Outer surface 30b: Axial annular plane 40: Spokes 50: Tread 50a: Vulcanized tread rubber 61: Envelope 61a: End part 62: Closed space 71: Pressurized pot 72: Jig 81: External space 82: First internal space 83: Second internal space (inner peripheral space)

Claims

1. A method for manufacturing a non-pneumatic tire having a support structure having an outer annular portion and a tread fixed to the outer annular portion, A process of temporarily bonding the vulcanized tread rubber to the outer surface of the outer ring portion of the support structure, A step of covering the vulcanized tread rubber with an envelope, A step of forming a sealed space between the envelope and the vulcanized tread rubber, The process of placing the support structure, the vulcanized tread rubber, and the envelope in a pressurized vessel, The process involves pressurizing and heating the inside of the pressurized oven to vulcanize and bond the vulcanized tread rubber to the outer surface, A method for manufacturing a non-pneumatic tire, comprising the following features.

2. The method for manufacturing a non-pneumatic tire according to claim 1, wherein the step of forming the sealed space includes pressing a part of the envelope against the axial annular plane of the outer annular portion of the support structure using a jig.

3. The method for manufacturing a non-pneumatic tire according to claim 2, wherein the step of pressing a part of the envelope against the axial annular plane of the outer annular portion of the support structure includes the step of using the jig to clamp the end portion of the envelope against the axial annular plane of the outer annular portion of the support structure.

4. The method for manufacturing a non-pneumatic tire according to claim 2 or 3, wherein the jig has a communication portion that connects an external space located inside the pressurized vessel and outside the jig with an internal space on the inner side of the outer annular portion of the support structure within the jig.

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