Method and apparatus for manufacturing pneumatic tires

Abstract

To provide a method and apparatus for manufacturing a pneumatic tire that can reduce an occurrence of defects during molding by appropriately calculating a clearance between chucks that hold bead parts.SOLUTION: A method for manufacturing a pneumatic tire includes: producing a first case body having a pair of bead parts; generating a second case body including a belt; calculating a first distance in a tire axial direction from an outer edge of the belt to an inner edge of the bead part based on a rise height along a tire radial direction from an inner end of the bead part to an outer end of the belt when the first case body and the second case body are integrated and a rise angle from the inner end of the bead part to the outer end of the belt; calculating a second distance by adding the first distance to an axial dimension of the belt from both ends of the belt in the tire axial direction toward an outside in the tire axial direction; and reducing a clearance along the tire axial direction between the bead parts held by a pair of chucks to the second distance while inflating the first case body, and unifying the first case body and the second case body.SELECTED DRAWING: Figure 7

Description

Technical Field

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

Background Art

[0002] A pneumatic tire is manufactured by integrating a first case body formed by molding a plurality of tire members such as a carcass and a second case body formed by molding a plurality of tire members such as tread rubber and a belt into one green tire (raw tire), and then heating and pressurizing the green tire in a mold for vulcanization molding (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As shown in FIG. 9, the process of forming the first case body T1 and the second case body T2 into one green tire will be described. With the second case body T2 positioned outside the first case body T1 in the tire radial direction RD, the bead portion 1 of the first case body T1 is held by the pair of chucks 510 of the molding device. The separation distance between the bead portions 1 before inflation is the initial distance L3. Next, while the first case body T1 is being inflated, the pair of chucks 510 approach until the separation distance between the bead portions 1 becomes the second distance L2, and the first case body T1 and the second case body T2 are integrated. After this, sidewall rubber may be attached while the integrated first case body T1 and second case body T2 are held by the pair of chucks 510.

[0005] As shown in Figure 9, the second distance L2 was determined such that the initial distance L3 coincided with half the circumference of a circle whose diameter was the second distance L2. In this case, the second distance L2 may be smaller than the axial dimension L0 of the belt 6 along the tire axial direction AD. In this case, the inflated first case body T1 and second case body T2 may not be able to stand firmly and may wobble, and the bead portion 1 of the integrated first case body T1 may come off the chuck 510, potentially causing problems such as stopping the molding process.

[0006] This disclosure provides a method and apparatus for manufacturing pneumatic tires that can reduce the occurrence of defects during molding by appropriately calculating the separation distance of the chucks that hold the bead portion. [Means for solving the problem]

[0007] The method for manufacturing a pneumatic tire according to this disclosure involves winding a plurality of tire components, including an inner liner and a carcass, onto a carcass band drum to produce a cylindrical first case body having a pair of bead portions; winding a plurality of tire components, including tread rubber and a belt, onto a belt drum to produce a cylindrical second case body; and determining the rise height along the tire radial direction from the inner end of the bead portion to the outer end of the belt and the rise angle from the inner end of the bead portion toward the outer end of the belt in a state in which the first case body and the second case body are integrated. The method includes: calculating a first distance in the tire axial direction from the outer end of the belt to the inner end of the bead portion; calculating a second distance by adding the first distance to the tire axial dimension of the belt from both ends of the belt in the tire axial direction toward the tire axial side; and, while holding the pair of bead portions of the first case body with the pair of chucks, inflating the first case body and reducing the distance between the bead portions held by the pair of chucks in the tire axial direction to the second distance, thereby integrating the first case body and the second case body.

[0008] The pneumatic tire manufacturing apparatus of the present disclosure comprises a carcass band drum around which a plurality of tire members, including an inner liner and a carcass, are wound to produce a cylindrical first case body having a pair of bead portions, and a belt drum around which a plurality of tire members, including tread rubber and a belt, are wound to produce a cylindrical second case body. The apparatus is configured to hold the pair of bead portions of the first case body with a pair of chucks, inflate the first case body, and reduce the distance between the pair of chucks along the tire axis direction to a second distance, thereby integrating the first case body and the second case body. Based on the rise height along the tire radial direction from the inner end of the bead portion to the outer end of the belt and the rise angle from the inner end of the bead portion to the outer end of the belt in the integrated state of the first and second case bodies, a first distance in the tire axis direction from the outer end of the belt to the inner end of the bead portion is calculated. The second distance is calculated by adding the first distance to the tire axis dimension of the belt from both ends of the belt in the tire axis direction toward the tire axis outward. [Brief explanation of the drawing]

[0009] [Figure 1] A schematic diagram of the tire's meridian cross-section illustrating the structure of a green tire. [Figure 2] A diagram showing the molding process for the first case body. [Figure 3] A diagram illustrating the operation of each component in a pneumatic tire manufacturing system. [Figure 4] A diagram showing the molding process for the second case body. [Figure 5] An explanatory diagram regarding the process of integrating the first case body and the second case body. [Figure 6] An explanatory diagram regarding the process of integrating the first case body and the second case body. [Figure 7] An explanatory diagram regarding the method for determining the second distance. [Figure 8] An explanatory diagram regarding the method for determining the second distance. [Figure 9] An explanatory diagram of the conventional method for determining the second distance. [Modes for carrying out the invention]

[0010] Hereinafter, a first embodiment of this disclosure will be described with reference to the drawings.

[0011] [Structure of Green Tire T3 (Raw Tire)] Figure 1 is a schematic meridian cross-sectional view of the green tire T3. In this figure, gaps are shown between some of the tire components for ease of understanding. As shown in Figure 1, the green tire T3 comprises a pair of bead portions 1, sidewalls 2 extending radially outward RD1 from each bead portion 1, and a tread 3 connecting the radially outward RD1 ends of the sidewalls 2. The bead portion 1 has an annular bead core 1a made of a converging body such as steel wire covered with rubber, a bead filler 1b made of hard rubber, and a chevron 1c covering the bead core 1a. The green tire T3 also has a toroidal carcass 4 that is arranged to span between the pair of bead portions 1 and extends from the tread 3 through the sidewalls 2 to the bead portions 1. At least one carcass 4 is provided, and the end of the carcass 4 is locked in a state where it is wound up over the bead core 1a. An inner liner 5 for maintaining air pressure is arranged on the inner circumference side of the carcass 4. Multiple belts 6 (two in this embodiment) are arranged around the outer circumference of the carcass 4 in the tread 3 to reinforce the carcass 4 by their effect. Each of the multiple belts 6 has a metal cord that extends at a predetermined angle inclined with respect to the circumferential direction of the tire. The multiple belts 6 are laminated so that the metal cords intersect each other in opposite directions. A belt reinforcement layer 7 having non-metallic cords such as resin cords is arranged on the outer circumference side of the multiple belts 6, and tread rubber 8 is further arranged on the outer surface of the belt reinforcement layer 7. Sidewall rubber 9, which forms the side of the tire, is arranged around the outer circumference of the carcass 4 in the sidewall 2.

[0012] [Manufacturing method for pneumatic tires] A method for manufacturing a pneumatic tire includes the steps of: laminating multiple tire components to manufacture a green tire T3; and heating and pressurizing the green tire T3 in a mold to vulcanize it. A method for manufacturing a green tire T3 also includes the steps of: molding a first case body T1, also called the first case; molding a second case body T2, also called the second case; and inflating the first case body T1 and combining it with the second case body T2 to obtain a green tire T3.

[0013] [Molding of the first case T1] The process of forming the first case body T1 will be explained using Figure 2. Figure 2 is a diagram showing the molding process of the first case body T1. As shown in Figure 2, the inner liner 5, the chamfer 1c, and the carcass 4 are wrapped around the carcass band drum 50. Then, the bead filler 1b and the bead core 1a are placed at both ends of the carcass 4 to form the first case body T1. Depending on the case, all or part of the sidewall rubber 9 may be integrated. The formed first case body T1 is transported from the carcass band drum 50 to the molding device 51 (also called a shaving drum) by a carcass transfer 52, as shown in Figure 3. Figure 3 is a diagram showing the operation of each device that constitutes the pneumatic tire manufacturing system.

[0014] [Molding of the second case body T2 (second case)] The process of forming the second case body T2 will be explained using Figure 4. Figure 4 is a diagram showing the molding process of the second case body T2. As shown in Figure 4, after the belt 6 and belt reinforcement layer 7 (not shown in the figure) are wrapped around the belt drum 53, the tread rubber 8 is wrapped around the entire circumference of the tire to obtain the second case body T2. The molded second case body T2 is conveyed from the belt drum 53 to the molding apparatus 51 by a belt transfer 54, as shown in Figure 3.

[0015] [Combination of Case 1 T1 and Case 2 T2] Figs. 5 to 6 are explanatory views regarding the process of integrating the first case body T1 and the second case body T2. As shown in Fig. 5, a pair of chucks 510 of the molding device 51 hold the bead portions 1 of the first case body T1, and the separation distance between the bead portions 1 held by the pair of chucks 510 is set to the initial distance L3. The separation distance between the bead portions 1 is the distance along the tire axial direction AD between the inner ends P2 of the bead portions 1 (see Fig. 7, the ends on the inner side in the tire diameter direction and the inner side in the tire axial direction). The initial distance L3 is set according to the distance between the bead portions 1 of the first case body T1 before inflation. The second case body T2 is held by the belt transfer 54 and is arranged in a state where the tire equatorial plane coincides with the outer side RD1 in the tire diameter direction of the first case body T1.

[0016] Next, the carcass 4 of the first case body T1 is wound up by a turn-up bladder (not shown), and as shown in Fig. 6, while inflating the first case body T1 with an inflate bladder (not shown), the separation distance between the bead portions 1 along the tire axial direction AD is reduced to the second distance L2. Next, the second case body T2 is pressed against the first case body T1 by a stitcher (not shown) to join the second case body T2 and the first case body T1, thereby forming a green tire T3. In this embodiment, although not shown, after integrating the first case body T1 and the second case body T2, the sidewall rubber 9 is attached.

[0017] In the above process, the second distance L2 is defined as follows. FIGS. 7 and 8 are explanatory diagrams regarding the method for determining the second distance L2. As shown in FIGS. 7 and 8, the rising height H1 along the tire radial direction RD from the inner end P2 of the bead portion 1 to the outer end P1 of the belt 6 (the outermost end in the tire axial direction AD of the belt 6) in the state where the first case body T1 and the second case body T2 are integrated is specified. The rising height H1 can be calculated based on the diameter φ1 of the belt drum 53 and the diameter φ2 of the carcass band drum 50. Specifically, it can be calculated by the difference in diameters between the belt drum 53 and the carcass band drum 50, that is, H1 = (φ1 - φ2) / 2. In the present embodiment, the belt 6 serving as the reference for specifying the rising height H1 is the first belt (counted as the first and second from the inner side to the outer side in the tire radial direction RD), but it is not limited to the first belt. For example, the belt 6 having the longest tire axial length among the plurality of belts 6 having metal cords is targeted. The same applies to the belt 6 serving as the reference for specifying the rising angle θ described later.

[0018] Also, the rising angle θ from the inner end P2 of the bead portion 1 toward the outer end P1 of the belt 6 is specified. The rising angle θ can be calculated based on the tire cross-sectional height after tire vulcanization. Since the tire cross-sectional height after tire vulcanization is almost the same as the tire cross-sectional height of the green tire T3 before tire vulcanization, it can be used. Specifically, a plurality of data associating the tire cross-sectional height and the rising angle θ are stored in the memory of the molding device 51. For example, it is associated that the rising angle θ is 85 degrees for a tire cross-sectional height of less than 100 mm, the rising angle θ is 80 degrees for a tire cross-sectional height of 100 mm or more and less than 120 mm, and the rising angle θ is 75 degrees for a tire cross-sectional height of 120 mm or more and 140 mm or less. The molding device 51 specifies the rising angle θ corresponding to the tire cross-sectional height designated by the user based on the plurality of data.

[0019] Next, based on the rise height H1 and the rise angle θ, the first distance L1 in the tire axial direction AD from the outer end P1 of the belt 6 to the inner end P2 of the bead portion 1 is calculated. The first distance L1 can be calculated using the formula L1 = H1 / tanθ.

[0020] Next, the second distance L2 is calculated by adding the first distance L1 from both ends of the tire axial direction AD of belt 6 toward the tire axial direction outward, to the tire axial dimension L0 of belt 6. That is, L2 = L0 + L1 × 2. This makes it possible to calculate the appropriate second distance L2.

[0021] [Differentiation] (A) In the above embodiment, the sidewall rubber 9 is attached after the first case body T1 and the second case body T2 are integrated, but the embodiment is not limited to this. All or part of the sidewall rubber 9 may be attached to the first case body T1 in advance.

[0022] (B) The tires of the above embodiment are for passenger cars, but are not limited to this. For example, they may be for light trucks (LT).

[0023] [1] As described above, the method for manufacturing a pneumatic tire involves winding a plurality of tire components, including an inner liner 5 and a carcass 4, around a carcass band drum 50 to create a cylindrical first case body T1 having a pair of bead portions 1; winding a plurality of tire components, including tread rubber 8 and a belt 6, around a belt drum 53 to create a cylindrical second case body T2; and, based on the rise height H1 along the tire radial direction RD from the inner end P2 of the bead portion 1 to the outer end P1 of the belt 6 in the state in which the first case body T1 and the second case body T2 are integrated, and the rise angle θ from the inner end P2 of the bead portion 1 toward the outer end P1 of the belt 6, the belt 6 The method may also include: calculating a first distance L1 in the tire axial direction AD from the outer end P1 of the belt to the inner end P2 of the bead portion 1; calculating a second distance L2 by adding the first distance L1 to the tire axial dimension L0 of the belt 6 from both ends (P1, P1) of the tire axial direction AD toward the outside of the tire axial direction AD; and, while holding the pair of bead portions 1 of the first case body T1 with the pair of chucks 510, inflating the first case body T1 and reducing the distance between the bead portions 1 held by the pair of chucks 510 along the tire axial direction AD to the second distance L2, thereby integrating the first case body T1 and the second case body T2.

[0024] Thus, the second distance L2, which is the distance between the inner ends of the bead portion 1, is obtained by adding the first distance L1 from both ends (P1, P1) of the tire axial direction AD of the belt 6 toward the outside of the tire axial direction AD. Therefore, it is possible to suppress the wobbling of the green tire T3 and prevent the occurrence of problems caused by wobbling.

[0025] [2] In the method for manufacturing a pneumatic tire described in [1] above, the rise height H1 may be calculated based on the difference in diameter between the carcass band drum 50 and the belt drum 53, and the rise angle θ may be calculated based on the tire cross-sectional height after tire vulcanization. In this way, the value can be calculated based on the specifications of the vulcanized tire (tire section height) and the manufacturing conditions of the manufacturing equipment (diameter difference between the carcass band drum 50 and the belt drum 53) that are matched to the vulcanized tire, thus enabling the uniform determination of the second distance L2.

[0026] [3] In the method for manufacturing a pneumatic tire described in [2] above, the rising angle θ corresponding to a specified tire cross-sectional height may be identified based on a plurality of data relating the rising angle θ to the tire cross-sectional height, and the first distance L1 may be calculated using the identified rising angle θ. This approach allows for compatibility with multiple tire sizes.

[0027] [4] In the method for manufacturing a pneumatic tire described in [3] above, it may be stated that a tire section height of 99 mm or less is associated with a rise angle θ of 85 degrees, a tire section height of 100 mm or more and 119 mm or less is associated with a rise angle θ of 80 degrees, and a tire section height of 120 mm or more and 140 mm or less is associated with a rise angle θ of 75 degrees. This is a preferred example.

[0028] [5] The pneumatic tire manufacturing apparatus of this embodiment comprises a carcass band drum 50 on which a plurality of tire components, including an inner liner 5 and a carcass 4, are wound to produce a cylindrical first case body T1 having a pair of bead portions 1, and a belt drum 53 on which a plurality of tire components, including tread rubber 8 and a belt 6, are wound to produce a cylindrical second case body T2. With the pair of bead portions 1 of the first case body T1 held by a pair of chucks 510, the first case body T1 is inflated while the distance between the pair of chucks 510 along the tire axis AD is reduced to a second distance L2, and the first case body T1 and the second case body T2 are... The components are configured to be integrated, and when the first case body T1 and the second case body T2 are integrated, the first distance L1 in the tire axial direction AD from the outer end P1 of the belt 6 to the inner end P2 of the bead portion 1 is calculated based on the rise height H1 along the tire radial direction RD from the inner end P2 of the bead portion 1 to the outer end P1 of the belt 6 and the rise angle θ from the inner end P2 of the bead portion 1 to the outer end P1 of the belt 6. The second distance L2 is calculated by adding the first distance L1 to the tire axial dimension L0 of the belt 6 from both ends (P1, P1) of the tire axial direction AD toward the outside of the tire axial direction AD.

[0029] Although embodiments of this disclosure have been described above with reference to the drawings, it should be understood that the specific configurations are not limited to these embodiments. The scope of this disclosure is indicated not only by the description of the embodiments above but also by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.

[0030] The structures adopted in each of the above embodiments can be adopted in any other embodiment. The specific configuration of each part is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of this disclosure.

[0031] For example, the execution order of operations, procedures, steps, and stages in the devices, systems, programs, and methods shown in the claims, specifications, and drawings can be implemented in any order, as long as the output of a previous process is not used in a later process. Even if the flow in the claims, specifications, and drawings is described using terms such as "first," "next," etc., for convenience, it does not mean that the execution must be in that order. [Explanation of Symbols]

[0032] 1: Bead section 3: Tread 4: Carcass 5: Inner liner 6: Belt 8: Tread Rubber 50: Carcass Band Drums 53: Belt Drum 510: Chuck AD: Tire axis H1: Rise height L0: Axial dimension of the tire L1: 1st distance L2: 2nd distance P1: Outer end of belt 6 P2: Inner end of bead portion 1 RD: Tire radial direction T1: Case 1 T2: Second case body θ: Rising angle

Claims

1. Multiple tire components, including an inner liner and a carcass, are wrapped around a carcass band drum to create a cylindrical first case body having a pair of bead portions. Multiple tire components, including tread rubber and belts, are wound around a belt drum to create a cylindrical second case body. Based on the rise height along the tire radial direction from the inner end of the bead portion to the outer end of the belt and the rise angle from the inner end of the bead portion to the outer end of the belt in the state in which the first case body and the second case body are integrated, a first distance in the tire axial direction from the outer end of the belt to the inner end of the bead portion is calculated, The second distance is calculated by adding the first distance to the tire axial dimension of the belt, from both ends of the belt in the tire axial direction toward the tire axial side, respectively. With the pair of bead portions of the first case body held by the pair of chucks, the first case body is inflated while reducing the distance between the bead portions held by the pair of chucks along the tire axis to a second distance, thereby integrating the first case body and the second case body. A method for manufacturing pneumatic tires, including

2. The method for manufacturing a pneumatic tire according to claim 1, wherein the rise height is calculated based on the difference in diameter between the carcass band drum and the belt drum, and the rise angle is calculated based on the tire cross-sectional height after tire vulcanization.

3. A method for manufacturing a pneumatic tire according to claim 2, comprising identifying the rise angle corresponding to a specified tire cross-sectional height based on a plurality of data relating the rise angle and the tire cross-sectional height, and calculating the first distance using the identified rise angle.

4. A method for manufacturing a pneumatic tire according to claim 3, wherein a tire section height of less than 100 mm is associated with a rise angle of 85 degrees, a tire section height of 100 mm or more and less than 120 mm is associated with a rise angle of 80 degrees, and a tire section height of 120 mm or more and 140 mm or less is associated with a rise angle of 75 degrees.

5. A carcass band drum in which multiple tire components, including an inner liner and a carcass, are wound together to form a cylindrical first case body having a pair of bead portions, A belt drum is provided, around which multiple tire components, including tread rubber and belts, are wound to form a cylindrical second case body. The first case body is configured to hold the pair of bead portions of the first case body with the pair of chucks, inflate the first case body, and reduce the distance between the pair of chucks along the tire axis to a second distance, thereby integrating the first case body and the second case body. Based on the rise height along the tire radial direction from the inner end of the bead portion to the outer end of the belt and the rise angle from the inner end of the bead portion to the outer end of the belt in the state in which the first case body and the second case body are integrated, a first distance in the tire axial direction from the outer end of the belt to the inner end of the bead portion is calculated. A pneumatic tire manufacturing apparatus, wherein the second distance is calculated by adding the first distance to the tire axial dimension of the belt, from both ends of the belt in the tire axial direction toward the tire axial side.

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