Method for manufacturing pneumatic tires and apparatus for manufacturing pneumatic tires

Abstract

The present invention provides a method for manufacturing pneumatic tires that can reduce poor adhesion between the bead filler and the carcass ply. [Solution] A method for manufacturing a pneumatic tire 100, wherein a stitch roller 30 presses the bead filler 106 toward the carcass ply 109 to press the bead filler 106 against the carcass ply 109, wherein when pressing the inner filler side 106A of the bead filler 106, the bead filler 106 is pressed by a stitch roller 30 set to a first pressing force P1, and when pressing the outer filler side 106B of the bead filler 106, the bead filler 106 is pressed by a stitch roller 30 set to a second pressing force P3.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing a pneumatic tire and a manufacturing apparatus for a pneumatic tire.

Background Art

[0002] The manufacturing process of a pneumatic tire includes a tire molding process, a tire vulcanization process, etc. In the tire molding process, members such as a tread, a carcass, and a bead that constitute a pneumatic tire are integrated, wound around a molding drum, and formed into the shape of a pneumatic tire to form a green tire.

[0003] The tire molding process includes a process of winding a carcass ply around the outer periphery of a cylindrical molding drum, then arranging an annular bead at both axial ends of the molding drum, and pushing down the bead filler of the bead toward the center side of the molding drum to crimp it to the carcass ply on the molding drum (for example, Patent Document 1).

[0004] In the process of crimping the above-mentioned bead filler to the carcass ply, the bead filler is pressed toward the carcass ply by a stitch roller to crimp the bead filler to the carcass ply. Conventionally, even when crimping the inner side in the tire radial direction of the bead filler (the base side of the bead filler having a substantially triangular shape in a cross-sectional view in the tire axial direction, hereinafter referred to as the inner side of the filler), or even when crimping the outer side in the tire radial direction of the bead filler (the tip side of the substantially triangular shape, hereinafter referred to as the outer side of the filler), the bead filler is pressed toward the carcass ply by a stitch roller set to the same pressing force to crimp the bead filler to the carcass ply.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, the inner side of the bead filler is thicker in the direction of pressure compared to the outer side. Therefore, if the inner side of the filler is pressed using the same pressure as the outer side of the filler, the pressure may be insufficient, and the inner side of the filler may not be pressed against the carcass ply. In this case, the bead filler and carcass ply are not pressed together, air remains between the bead filler and the carcass ply, and the product is judged as defective.

[0007] On the other hand, the outer surface of the bead filler has less thickness in the pressing direction compared to the inner surface. Therefore, if the outer surface of the filler is pressed with the same pressure as that used for pressing the inner surface of the filler, the outer surface may be pressed excessively, reducing its adhesive properties and preventing it from being properly pressed against the carcass ply. In this case, the bead filler and carcass ply are not properly pressed together, air remains trapped between them, and the product is deemed defective.

[0008] Therefore, the present invention aims to provide a method for manufacturing pneumatic tires and an apparatus for manufacturing pneumatic tires that can reduce poor adhesion between the bead filler and the carcass ply. [Means for solving the problem]

[0009] The present invention relates to a method for manufacturing a pneumatic tire, which involves pressing a bead filler toward a carcass ply with a stitch roller to press the bead filler toward the carcass ply, characterized in that when pressing the inner side of the bead filler in the tire radial direction, the bead filler is pressed with a stitch roller set to a first pressing force, and when pressing the outer side of the bead filler in the tire radial direction, the bead filler is pressed with a stitch roller set to a second pressing force.

[0010] The present invention relates to a pneumatic tire manufacturing apparatus that presses a bead filler toward a carcass ply with a stitch roller to press the bead filler against the carcass ply, characterized in that when pressing the inner side of the bead filler in the tire radial direction, the bead filler is pressed by a stitch roller set to a first pressing force, and when pressing the outer side of the bead filler in the tire radial direction, the bead filler is pressed by a stitch roller set to a second pressing force. [Effects of the Invention]

[0011] According to the method for manufacturing pneumatic tires and the apparatus for manufacturing pneumatic tires of the present invention, poor adhesion between the bead filler and the carcass ply can be reduced. [Brief explanation of the drawing]

[0012] [Figure 1] This is a cross-sectional view of a pneumatic tire according to an embodiment, showing a half-section in the axial direction of the tire. [Figure 2] This is a plan view showing a bead crimping device, which is an example of an embodiment. [Figure 3] This is a side view showing a bead crimping device, which is an example of an embodiment. [Figure 4] This is a flowchart showing a bead crimping process, which is an example of an embodiment. [Figure 5] This is a schematic diagram showing a bead placement process, which is an example of an embodiment. [Figure 6] This is a schematic diagram showing the first pressing step, which is an example of an embodiment. [Figure 7] This is a schematic diagram showing a rotary process, which is one example of an embodiment. [Figure 8] This is a schematic diagram showing a traverse process, which is one example of an embodiment. [Figure 9] This is a schematic diagram showing a second pressing step, which is an example of an embodiment. [Modes for carrying out the invention]

[0013] Hereinafter, an example of an embodiment of the present invention will be described in detail. In the following description, specific shapes, materials, directions, numerical values, etc. are examples for facilitating the understanding of the present invention and can be appropriately changed according to applications, purposes, specifications, etc.

[0014] [Pneumatic Tire] The pneumatic tire 100 according to the embodiment will be described with reference to FIG. 1.

[0015] The pneumatic tire 100 includes a tread 101 which is a portion contacting the road surface, a pair of sidewalls 102 disposed on both sides of the tread 101, and a pair of beads 103 disposed on the inner side in the tire radial direction of the sidewall 102. Further, the pneumatic tire 100 includes a carcass 104 spanned between the pair of beads 103.

[0016] The sidewall 102 is disposed on both sides of the tread 101 and is provided annularly along the tire circumferential direction. The sidewall 102 is the portion that protrudes most to the outer side in the tire axial direction of the pneumatic tire 100 and is gently curved so as to be convex toward the outer side in the tire axial direction. The sidewall 102 has a function of preventing damage to the carcass 104.

[0017] The bead 103 is disposed on the inner side in the tire radial direction of the sidewall 102 and is a portion fixed to the rim of the wheel. The bead 103 has a bead core 105 and a bead filler 106. The bead core 105 is composed of a steel bead wire and is an annular member extending over the entire circumference in the tire circumferential direction and is embedded in the bead 103. The bead filler 106 has a substantially triangular shape with a tapered tip extending to the outer side in the tire radial direction in a cross-sectional view in the tire axial direction and is an annular hard rubber member extending over the entire circumference in the tire circumferential direction.

[0018] The carcass 104 is stretched between a pair of beads 103 and is locked by being folded around the bead core 105. The carcass 104 is composed of at least one carcass ply 109 (see FIG. 5). The carcass ply 109 is formed by coating a carcass cord made of organic fibers with coating rubber. The carcass cord is arranged substantially perpendicular to the tire circumferential direction (for example, 80° or more and 90° or less). Examples of the organic fibers used for the carcass cord include polyester fibers, rayon fibers, aramid fibers, nylon fibers, and the like.

[0019] The pneumatic tire 100 further includes a belt layer 107 disposed on the outer periphery of the crown portion of the carcass 104 and a belt reinforcing layer 108 disposed on the outer periphery of the belt layer 107. That is, the belt layer 107 is disposed between the carcass 104 and the tread 101, and the belt reinforcing layer 108 is disposed between the belt layer 107 and the tread 101.

[0020] [Bead crimping device] An example of the bead crimping device 10 of the embodiment will be described with reference to FIGS. 2 and 3.

[0021] The bead crimping device 10 as a manufacturing device for the pneumatic tire 100 is a device that crimps the bead filler 106 to the carcass ply 109 in a bead crimping process, which will be described in detail later. According to the bead crimping device 10, although details will be described later in the description of the bead crimping process, it is possible to reduce the crimping failure between the bead filler 106 and the carcass ply 109. The bead crimping device 10 includes a molding drum 20, a stitch roller 30, a driving device 40, and a control unit (not shown), the details of which will be described later.

[0022] The molding drum 20 is a cylindrical member around which the carcass ply 109 is wound. The molding drum 20 is rotatable around a cylindrical shaft by, for example, an electric motor. In the following, other members may be described according to the axial direction, radial direction, and circumferential direction of the cylindrical molding drum 20.

[0023] The stitch roller 30 is a component that presses the bead filler 106 toward the carcass ply 109. This allows the bead filler 106 to be pressed against the carcass ply 109. In the bead pressing device 10, the pair of stitch rollers 30 are positioned at predetermined distances from both axial ends and radial outer ends (upper ends) of the molding drum 20.

[0024] The stitch roller 30 is formed in a substantially cylindrical shape and has a cylindrical body and a tip that tapers toward the tip. However, the stitch roller of the present invention is not limited to the shape of the stitch roller 30 in this embodiment. The stitch roller 30 is rotatably supported around a substantially cylindrical axis. The stitch roller 30 is driven by a drive device 40, which will be described in detail later.

[0025] The drive unit 40 is a device that drives the stitch roller 30 in order to press the bead filler 106 onto the carcass ply 109 wound around the molding drum 20. The drive unit 40 has a swing drive unit 41, a rotary drive unit 42, a traverse drive unit 43, and a radial drive unit 44, which will be described in detail later.

[0026] The swing drive unit 41 drives the stitch roller 30 to swing. Swinging drive means swinging the stitch roller 30 so as to press it against the molding drum 20 (arrow S in Figure 2). The swing drive unit 41 may be composed of, for example, an air cylinder, a hydraulic cylinder, etc. With the swing drive unit 41, as will be explained in detail in the first pressing step S12 or the second pressing step S15 described later, the bead filler 106 can be pressed against the carcass ply 109 by pressing the bead filler 106 toward the carcass ply 109.

[0027] The pressing force of the swing drive unit 41 can be switched between a first pressing force P1 and a second pressing force P2. In the swing drive unit 41, the first pressing force P1 is set to be greater than the second pressing force P2. Furthermore, it is preferable that the first pressing force P1 is 0.37 MPa or more and 0.43 MPa or less. In addition, it is preferable that the second pressing force P2 is 0.20 MPa or more and 0.26 MPa or less. Moreover, it is preferable that the ratio of the first pressing force P1 to the second pressing force P2 is 1.42 to 2.15.

[0028] The switching of the pressing force of the swing drive unit 41 is achieved by a circuit consisting of a pump, a solenoid valve, a pressure reducing valve, the cylinder described above, etc. In this embodiment, a detailed explanation of the circuit is omitted.

[0029] The rotary drive unit 42 rotary drives the stitch roller 30 and the swing drive unit 41. Rotary drive means rotating the stitch roller 30 and the swing drive unit 41 around the shoulder portion 20S at a position within ±10 mm of both ends in the axial direction and within ±10 mm of the outer end in the radial direction of the molding drum 20 (hereinafter referred to as the shoulder portion 20S) (arrow R in Figure 3). The rotary drive unit 42 may be configured by, for example, an electric motor. The rotary drive unit 42 allows the bead filler 106 to be pushed down toward the carcass ply 109, although the details will be explained in the rotary process S13 described later.

[0030] The traverse drive unit 43 traverse drives the stitch roller 30, the swing drive unit 41, and the rotary drive unit 42. Traverse driving means reciprocating the stitch roller 30, the swing drive unit 41, and the rotary drive unit 42 in the axial direction of the molding drum 20 (arrow T in Figure 2). The traverse drive unit 43 may be composed of, for example, a ball screw, an electric motor, etc. With the traverse drive unit 43, as will be explained in detail in the traverse process S14 described later, the stitch roller 30 can be moved from the inner side 106A of the bead filler 106 in the tire radial direction to the outer side 106B of the bead filler 106.

[0031] The radial drive unit 44 radially drives the stitch roller 30, swing drive unit 41, rotary drive unit 42, and traverse drive unit 43. Radial drive means pressing the stitch roller 30, swing drive unit 41, rotary drive unit 42, and traverse drive unit 43 in the radial direction of the molding drum 20 (arrow Rd in Figure 2). The radial drive unit 44 may be composed of, for example, an air cylinder, a hydraulic cylinder, etc.

[0032] The control unit is composed of a computer such as a personal computer or a PLC (Programmable Logic Controller). The control unit has a CPU (Central Processing Unit) which is the arithmetic processing unit, and memory units such as RAM (Random Access Memory) and ROM (Read Only Memory), and performs signal processing according to a program pre-stored in ROM while utilizing the temporary storage function of RAM. The control unit is electrically connected to the swing drive unit 41, the rotary drive unit 42, the traverse drive unit 43, and the radial drive unit 44, and is configured to control the operation of each of these units.

[0033] [Bead crimping process] An example of an embodiment, the bead crimping process, will be explained using Figures 4 to 9.

[0034] The bead pressing process as a manufacturing method for the pneumatic tire 100 is a process in which the bead filler 106 is pressed onto the carcass ply 109 using the bead pressing device 10 described above. As will be described in detail later, the bead pressing process can reduce poor adhesion between the bead filler 106 and the carcass ply 109.

[0035] The bead pressing process is one step in the tire molding process. In the tire molding process, components such as the tread 101, carcass 104, and bead 103 that make up the pneumatic tire 100 are assembled, wound onto a molding drum 20, and molded into the shape of the pneumatic tire 100 to form a green tire. The tire molding process is one step in the tire manufacturing process. The tire manufacturing process includes the tire molding process, the tire vulcanization process, and so on.

[0036] As shown in Figure 4, the bead crimping process includes the bead placement process S11, the first pressing process S12, the rotary process S13, the traverse process S14, and the second pressing process S15, each of which will be described in detail later.

[0037] As shown in Figure 5, the bead placement process S11 is the process of placing the bead 103 on the carcass ply 109. In the bead placement process S11, the carcass ply 109 is wound around the outer circumferential surface of the molding drum 20. At this time, bladder 50, which has a smaller diameter than the molding drum 20, is placed at both axial ends of the molding drum 20. The bladder 50 is a component that expands toward the molding surface of the mold during the tire vulcanization process. Therefore, when the carcass ply 109 is wound around the molding drum 20 and the bladder 50, a step 109S is formed in the carcass ply 109 between the molding drum 20 and the bladder 50.

[0038] In the bead placement process S11, an annular bead 103 is positioned on the step 109S of the carcass ply 109 wound around the molding drum 20. More specifically, in the bead placement process S11, the bead 103 is positioned on the carcass ply 109 such that the bead core 105 and the inner filler side 106A of the bead filler 106 in the tire radial direction (the root side of the bead filler 106, which has a roughly triangular cross-section in the tire axial direction) abut against the step 109S. The outer filler side 106B of the bead filler 106 in the tire radial direction is the tip side of the bead filler 106, which has a roughly triangular cross-section in the tire axial direction.

[0039] As shown in Figure 6, the first pressing step S12 is a step in which the inner filler side 106A of the bead filler 106 is pressed toward the bead filler 106 by the stitch roller 30 set to a first pressing force P1. This makes it possible to press the inner filler side 106A of the bead filler 106 against the step 109S of the carcass ply 109. In the first pressing step S12, the stitch roller 30 is driven to swing by the swing drive unit 41.

[0040] In the first pressing step S12, the first pressing force P1 is set to be greater than the second pressing force 92 in the second pressing step S15, which will be described later. Furthermore, it is preferable that the first pressing force P1 is 0.37 MPa or more and 0.43 MPa or less. The ratio of the first pressing force P1 to the second pressing force P2 is preferably 1.42 to 2.15.

[0041] As a result, when the stitch roller 30 is pressed against the inner filler 106A and outer filler 106B of the bead filler 106 in the tire radial direction, the pressing force (first pressing force P1) on the inner filler 106A, which has a larger thickness in the pressing direction compared to the outer filler 106B, is made greater than the pressing force (second pressing force P2) on the outer filler 106B, thereby preventing insufficient pressing force on the inner filler 106A of the bead filler 106. Consequently, the bead filler 106 and the carcass ply 109 are not properly compressed, and the number of cases in which air remains between the bead filler 106 and the carcass ply 109 and is judged as a defective product can be reduced.

[0042] As shown in Figure 7, the rotary process S13 is a process of pushing the bead filler 106 toward the carcass ply 109. In the rotary process S13, the stitch roller 30 is rotary driven by the rotary drive unit 42, and the bead filler 106 is pushed toward the carcass ply 109. In the rotary process S13, the pressing force of the swing drive unit 41 may be reduced from the first pressing force P1 to the second pressing force P2.

[0043] As shown in Figure 8, the traverse process S14 is a process in which the stitch roller 30 moves from the inside to the outside of the bead filler 106 in the tire radial direction. In the traverse process S14, the stitch roller 30 is driven by the traverse drive unit 43, and the stitch roller 30 moves from the inside 106A of the bead filler 106 to the outside 106B of the bead filler in the tire radial direction. In the traverse process S14, the pressing force of the swing drive unit 41 may be reduced from the first pressing force P1 to the second pressing force P2.

[0044] As shown in Figure 9, the second pressing step S15 is a step in which the outer filler 106B of the bead filler 106 is pressed toward the bead filler 106 by the stitch roller 30 which is set to a second pressing force P2. This allows the outer filler 106B of the bead filler 106 to be pressed against the carcass ply 109. In the second pressing step S15, the stitch roller 30 is driven to swing by the swing drive unit 41.

[0045] In the second pressing step S15, the second pressing force P2 is set to be smaller than the first pressing force P1. Furthermore, it is preferable that the second pressing force P2 is between 0.20 MPa and 0.26 MPa. The ratio of the first pressing force P1 to the second pressing force P2 is preferably between 1.42 and 2.15.

[0046] As a result, when the stitch roller 30 is pressed against the inner filler 106A and outer filler 106B of the bead filler 106 in the tire radial direction, the pressing force (second pressing force P2) on the outer filler 106B, which has a smaller thickness in the pressing direction compared to the inner filler 106A, is made smaller than the pressing force (first pressing force P1) on the inner filler 106A. This prevents the outer filler 106B of the bead filler 106 from being pressed more than necessary, thus preventing the adhesion from being lost. Consequently, the bead filler 106 and the carcass ply 109 are not properly bonded, and the amount of air remaining between the bead filler 106 and the carcass ply 109, which would result in a defective product, can be reduced.

[0047] [summary] The present invention is further described by the following embodiments. Configuration 1: A method for manufacturing a pneumatic tire, comprising pressing a bead filler toward a carcass ply with a stitch roller to press the bead filler against the carcass ply, When pressing the inner side of the bead filler in the radial direction of the tire, the bead filler is pressed by the stitch roller set to a first pressing force, and when pressing the outer side of the bead filler in the radial direction of the tire, the bead filler is pressed by the stitch roller set to a second pressing force. A method for manufacturing pneumatic tires. Configuration 2: A method for manufacturing a pneumatic tire as described in Configuration 1, The first pressing force is greater than the second pressing force. A method for manufacturing pneumatic tires. Configuration 3: A method for manufacturing a pneumatic tire as described in configuration 2, The aforementioned first pressing force is 0.37 MPa or more and 0.43 MPa or less. A method for manufacturing pneumatic tires. Configuration 4: A method for manufacturing a pneumatic tire as described in configuration 2, The second pressing force is 0.20 MPa or more and 0.26 MPa or less. A method for manufacturing pneumatic tires. Configuration 5: A method for manufacturing a pneumatic tire according to any one of items 1 to 4, The carcass ply is wound around a cylindrical molding drum, The stitch roller rotates around both axial ends and radial outer ends of the molding drum, thereby pushing the bead filler toward the carcass ply. A method for manufacturing pneumatic tires. Configuration 6: A pneumatic tire manufacturing apparatus that presses a bead filler toward a carcass ply with a stitch roller to press the bead filler against the carcass ply, When pressing the inner side of the bead filler in the radial direction of the tire, the stitch roller, set to a first pressing force, presses against the bead filler; when pressing the outer side of the bead filler in the radial direction of the tire, the stitch roller, set to a second pressing force, presses against the bead filler. A manufacturing device for pneumatic tires. Composition 7: A pneumatic tire manufacturing apparatus as described in configuration 6, The carcass ply is wound around a cylindrical molding drum, The stitch roller rotates around both axial ends and radial outer ends of the molding drum, thereby pushing the bead filler toward the carcass ply. A manufacturing device for pneumatic tires.

[0048] It should be noted that the present invention is not limited to the embodiments and their modifications described above, and various changes and improvements are possible within the scope of the claims of this application. [Explanation of Symbols]

[0049] 10 Bead pressing device (tire manufacturing equipment), 20 Molding drum, 20S Shoulder section, 30 Stitch roller, 30A Body section, 30B Tip section, 40 Drive unit, 41 Swing drive unit, 42 Rotary drive unit, 43 Traverse drive unit, 44 Radial drive unit, 50 Bladder, 100 Pneumatic tire, 101 Tread, 102 Sidewall, 103 Bead, 104 Carcass, 105 Bead core, 106 Bead filler, 106A Inner filler, 106B Outer filler, 107 Belt layer, 108 Belt reinforcement layer, 109 Carcass ply, 109S Step

Claims

1. A method for manufacturing a pneumatic tire, comprising pressing a bead filler toward a carcass ply with a stitch roller to press the bead filler against the carcass ply, When pressing the inner side of the bead filler in the tire radial direction, the bead filler is pressed by the stitch roller set to a first pressing force, and when pressing the outer side of the bead filler in the tire radial direction, the bead filler is pressed by the stitch roller set to a second pressing force. A method for manufacturing pneumatic tires.

2. A method for manufacturing a pneumatic tire according to claim 1, The first pressing force is greater than the second pressing force. A method for manufacturing pneumatic tires.

3. A method for manufacturing a pneumatic tire according to claim 2, The first pressing force is 0.37 MPa or more and 0.43 MPa or less. A method for manufacturing pneumatic tires.

4. A method for manufacturing a pneumatic tire according to claim 2, The second pressing force is 0.20 MPa or more and 0.26 MPa or less. A method for manufacturing pneumatic tires.

5. A method for manufacturing a pneumatic tire according to any one of claims 1 to 4, The carcass ply is wound around a cylindrical molding drum, The stitch roller rotates around both axial ends and radial outer ends of the molding drum, thereby pushing the bead filler toward the carcass ply. A method for manufacturing pneumatic tires.

6. A pneumatic tire manufacturing apparatus that presses a bead filler toward a carcass ply with a stitch roller to press the bead filler against the carcass ply, When pressing the inner side of the bead filler in the tire radial direction, the stitch roller set to a first pressing force presses the bead filler, and when pressing the outer side of the bead filler in the tire radial direction, the stitch roller set to a second pressing force presses the bead filler. A manufacturing device for pneumatic tires.

7. A pneumatic tire manufacturing apparatus according to claim 6, The carcass ply is wound around a cylindrical molding drum, The stitch roller rotates around both axial ends and radial outer ends of the molding drum, thereby pushing the bead filler toward the carcass ply. A manufacturing device for pneumatic tires.

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