Tire manufacturing methods

Abstract

To omit the process of combining components in the molding of raw tires.SOLUTION: A tire manufacturing method includes the steps of attaching a sheet-shaped rubber member 20 to first ply 30, forming second ply 40 and the first ply 30 with the rubber member 20 attached into a cylindrical shape along the outer circumference of a cylindrical forming former 110, and forming a wound body in which the second ply 40, first ply 30, and the rubber member 20 are arranged in this order from the inside in the radial direction, and forming a sidewall 17 of a raw tire by the first ply 30, the second ply 40, and the rubber member 20 by deforming the axial center of the wound body outward in the radial direction.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] This disclosure relates to a method for manufacturing a tire.

Background Art

[0002] For example, Patent Document 1 discloses a method for manufacturing a tire including an inner liner and sidewall rubber. In the method disclosed in Patent Document 1, an intermediate member including an unvulcanized inner liner and a pair of unvulcanized sidewall rubbers is wound around a drum to form a cylindrical shape. Then, a carcass ply is wound around the cylindrical intermediate member, and the pair of sidewall rubbers of the intermediate member are folded back around the bead core. Also, the central portion of the intermediate member is expanded radially outward. Further, a belt and tread rubber are attached to the outer side of the green tire being formed to form a green tire. According to Patent Document 1, in the above method, since a green tire is formed using an integrated intermediate member, it is not necessary to combine a plurality of tire constituent members of the intermediate member during the formation of the green tire. Therefore, it is said that the man-hours during the formation of the green tire can be reduced compared with the conventional method, and the production efficiency of the tire can be improved.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, a method for manufacturing another tire is proposed in which the step of combining members in the formation of a green tire can be omitted.

Means for Solving the Problems

[0005] The tire manufacturing method of the present invention includes the steps of: attaching a sheet-like rubber member to a first ply; forming a winding body; and forming the sidewall of a green tire. In the step of forming a winding body, the second ply and the first ply with the rubber member attached are formed into a cylindrical shape along the outer surface of a cylindrical molding former, forming a winding body in which the second ply, the first ply, and the rubber member are arranged in that order from the radially inner side. In the step of forming the sidewall of a green tire, the axial central part of the winding body is deformed radially outward to form the sidewall of the green tire with the first ply, the second ply, and the rubber member.

[0006] According to the above tire manufacturing method, the sidewall rubber of the green tire is formed by a sheet-like rubber member attached to the first ply before molding. Therefore, there is no need to combine the sidewall rubber during molding. Thus, according to the above tire manufacturing method, the process of combining the sidewall rubber can be omitted in the molding of the green tire. [Brief explanation of the drawing]

[0007] [Figure 1] This is a process diagram showing part of the tire manufacturing process. [Figure 2] This is a schematic side view of a rubber sheet molding machine. [Figure 3] This is a schematic side view of a floating ply with a rubber sheet attached. [Figure 4] This is a schematic partial fracture front view of a molding former during the molding of a floating ply. [Figure 5] This is a schematic partial fracture front view of a forming former during the formation of a carcass ply. [Figure 6] This is a schematic, partially broken front view of a molding former during bead formation. [Figure 7] This is a schematic partial fracture front view of a forming former during sidewall formation. [Modes for carrying out the invention]

[0008] The following describes a method for manufacturing a tire according to one embodiment, based on the drawings. However, the present invention is not limited to the following embodiment. Each drawing is schematic and does not necessarily reflect the actual object. Each drawing is merely an example and does not limit the present invention unless specifically mentioned. Furthermore, components and parts that perform the same function are appropriately denoted by the same reference numerals, and redundant explanations are omitted.

[0009] [Tire manufacturing process] Figure 1 is a process diagram showing a part of the manufacturing process for a tire according to one embodiment. In this embodiment, the tire is for a motorcycle. However, the type of tire is not particularly limited. Figure 1 illustrates the process of forming an intermediate cover 10 (see Figure 7 for all of them) which includes plies 30L, 30R, and 40, as part of the process of forming an unvulcanized green tire (raw cover).

[0010] As shown in Figure 1, in this embodiment, the tire manufacturing process includes a rubber sheet molding process S10, a bonding process S20, a winding process S30, and an inflation process S40. The winding process S30 further includes a floating ply 30 molding process S31, a carcass ply 40 molding process S32, and a bead molding process S33.

[0011] In the rubber sheet molding process S10, the rubber sheet 20 is formed by calendering. However, the method of forming the rubber sheet 20 is not limited as long as it can be formed into a predetermined shape. The rubber sheet 20 is a sheet-shaped rubber member. The rubber sheet 20 constitutes the sidewall rubber in the finished tire. The rubber sheet 20 is formed by thinly molding the material for the sidewall rubber. The thickness T of the rubber sheet 20 (see Figure 3) is preferably 2 mm or less. By forming the rubber sheet 20 thinly, the thickness of the tire's sidewall rubber is reduced. This increases the deformation of the tire when a load is applied to the side of the tire, improving the feel of contact with the road and ride comfort. However, the thickness of the rubber sheet 20 is not particularly limited.

[0012] Figure 2 is a schematic side view of a rubber sheet molding apparatus 100. As shown in Figure 2, one example of a rubber sheet molding apparatus 100 includes a plurality of heating rollers 101 and a plurality of cooling rollers 102. The material rubber G, which is the material for the rubber sheet 20, is kneaded in a kneader (not shown) and then extruded between the plurality of heating rollers 101. The material rubber G is rolled between the plurality of heating rollers 101 to form a sheet. The sheet-shaped material rubber G is cooled and its thickness is adjusted as it passes between the plurality of cooling rollers 102. This forms a rubber sheet 20 of a predetermined thickness (preferably 2 mm or less). The rubber sheet molding apparatus 100 may be the same apparatus used to mold inner liners or insulation.

[0013] In the attachment process S20, a rubber sheet 20 is attached to each of the pair of floating plies 30. Figure 3 is a schematic side view of the floating plies 30 with the rubber sheets 20 attached. As will be described in more detail later, the floating plies 30 are plies that support the sidewalls and are composed of pairs. Hereafter, when distinction is necessary, the floating ply 30 on the left side of the figure is indicated by reference numeral 30L, and the floating ply 30 on the right side of the figure is indicated by reference numeral 30R, for example, as shown in Figure 4. When it is not necessary to distinguish between the pair of floating plies 30, reference numeral 30 is used. Similarly, when distinction is necessary, the rubber sheet 20 on the left side of the figure is indicated by reference numeral 20L, and the rubber sheet 20 on the right side of the figure is indicated by reference numeral 20R (see, for example, Figure 4).

[0014] As shown in Figure 3, the rubber sheet 20 is attached to the floating ply 30 so that it extends outward from the side of the floating ply 30. The direction in which the rubber sheet 20 extends outward from the floating ply 30 (to the left in Figure 3) corresponds to the direction in which the bead portion 16 is viewed from the sidewall 17 in the intermediate cover 10 (see Figure 7). In the intermediate cover 10, the rubber sheet 20 extends further toward the bead portion 16 than the floating ply 30. Hereafter, the portion of the rubber sheet 20 that extends outward from the floating ply 30 will also be referred to as the overhang portion 20a. Note that the overhang portion 20a is not required.

[0015] In the winding body forming process S30, the carcass ply 40 and the floating ply 30 (hereinafter also simply referred to as the floating ply 30) to which the rubber sheet 20 is attached are formed into a cylindrical shape along the outer surface of a cylindrical molding former 110 (see Figure 4). This forms a winding body 15 (see Figure 6) in which the carcass ply 40, the floating ply 30, and the rubber sheet 20 are arranged in that order from the radially inner side.

[0016] In the winding body molding process S30, during the floating ply molding process S31, a pair of floating prisms 30, each with a rubber sheet 20 attached, are molded into a cylindrical shape along the outer surface of the molding former 110. Figure 4 is a schematic partially broken front view of the molding former 110 during the molding of the floating prisms 30. As shown in Figure 4, during the floating ply molding process S31, the pair of floating prisms 30L and 30R are positioned apart in the axial direction of the molding former 110. In Figure 4, the axial direction of the molding former 110 is the left-right direction. Specifically, the pair of floating prisms 30L and 30R are wound around the left and right ends of the cylindrical molding former 110, respectively. As shown in the broken section of Figure 4, the pair of floating prisms 30L and 30R are positioned such that the rubber sheet 20 is on the radially inward side of the molding former 110. Furthermore, the pair of floating pies 30L and 30R are positioned such that the overhang portion 20a of the rubber sheet 20 faces inward in the axial direction. The pair of floating pies 30L and 30R are each wrapped around the molding former 110 once, and both ends in the circumferential direction are joined.

[0017] In the winding body forming process S30, during the carcass ply forming process S32, the carcass ply 40 is superimposed on a pair of floating prisms 30 and formed into a cylindrical shape along the outer circumferential surface of the forming former 110. Figure 5 is a schematic partially broken front view of the forming former 110 during the forming of the carcass ply 40. As shown in Figure 5, in this embodiment, the carcass ply 40 is wound inward from the axially outer ends of the floating prisms 30. Each of the pair of floating prisms 30 protrudes axially outward from the carcass ply 40. However, the carcass ply 40 may be configured to have a longer axial length than shown in Figure 5, and may protrude outward from the axially outer ends of the floating prisms 30. The carcass ply 40 is wound around the forming former 110 once, and both ends in the circumferential direction are joined.

[0018] In the winding body forming step S30, the pair of floating plies 30 and the carcass ply 40 may be first overlapped, and if necessary, bonded together, and then wound by the forming former 110.

[0019] In the bead forming step S33 of the winding body forming step S30, the bead portions 16 are formed. FIG. 6 is a schematic partially broken front view of the forming former 110 during the formation of the bead portions 16. As shown in FIG. 6, in the bead forming step S33, both axial ends of the carcass ply 40 are wound up around the bead cores 50 to form a pair of bead portions 16. As a result, the pair of floating plies 30 and the rubber sheet 20 are turned inside out so that the rubber sheet 20 comes to the outside in the radial direction.

[0020] As shown in FIG. 6, at the axial end of the winding body 15, the protruding portion 20a of the rubber sheet 20 covers the outside of the bead portion 16. The rubber sheet 20 has a length that protrudes outside the axial end of the bead portion 16 after winding up both axial ends of the carcass ply 40 to form the bead portion 16. When the protruding portion 20a is not provided, the rubber sheet 20 may cover the outside of the bead portion 16 with the floating ply 30 interposed therebetween. Here, the floating ply 30 extends axially inside the ends 40L and 40R of the folded carcass ply 40. As shown in FIG. 6, by the winding body forming step S30, a cylindrical winding body 15 in which the carcass ply 40, the floating ply 30, and the rubber sheet 20 are arranged in this order from the inside in the radial direction is formed.

[0021] In the expansion process S40, the axial central portion of the winding body 15 is deformed radially outward to form the sidewall 17 of the green tire with the floating ply 30, carcass ply 40, and rubber sheet 20. Figure 7 is a schematic partially broken front view of the molding former 110 during the molding of the sidewall 17. The molding former 110 expands a bladder (not shown) and deforms the axial central portion of the winding body 15 so that it protrudes radially outward. As a result, as shown in Figure 7, an intermediate cover 10 is formed, which has a pair of sidewalls 17 and an outer peripheral portion 18 to which the tread rubber is assembled. In the sidewall 17, the carcass ply 40 is positioned on the inside, followed by the floating ply 30, and the rubber sheet 20 is positioned on the outside. In subsequent processes, the tread rubber and other materials are assembled to the intermediate cover 10 to form the green tire. The green tire undergoes processes such as vulcanization to become a finished tire. In the finished tire, the rubber sheet 20 constitutes the sidewall rubber.

[0022] Although omitted in the above explanation, the intermediate cover 10 may also incorporate other components, such as an inner liner or insulation.

[0023] [Examples] The following describes the examples and their evaluation results. Table 1 shows the manufacturing methods and evaluation results for the examples and comparative examples. [Table 1]

[0024] As shown in Table 1, the comparative example is a tire manufactured by the conventional method. In the conventional method, the rubber sheet 20 is not attached to the floating ply 30, and the sidewall rubber is assembled to the intermediate cover which is formed without sidewall rubber. The sidewall rubber is formed by extrusion molding. The thickness of the sidewall rubber is 3 mm. It is difficult to mold sidewall rubber thinner than 3 mm using extrusion molding. The comparative example is the thinnest example of sidewall rubber achieved using the conventional method.

[0025] In Examples 1 to 4, the tire is manufactured by the method described above, which involves attaching a rubber sheet 20 to a floating ply 30. In Example 1, the thickness of the rubber sheet 20 is 1 mm. In Example 2, the thickness of the rubber sheet 20 is 0.5 mm. In Example 3, the thickness of the rubber sheet 20 is 2 mm. In Example 4, the thickness of the rubber sheet 20 is 3 mm.

[0026] The "molding time" in the evaluation results represents the time required to mold the green tire. The molding time result is either "long" or "short". The "flex index" in the evaluation results is the amount of tire flex obtained in the flex test, standardized with Example 1 set to "100". A larger flex index indicates that the tire flexes more. The "handling performance" in the evaluation results is an index of handling stability, and a larger value indicates higher handling stability. Handling performance is a subjective evaluation by a test rider when the vehicle fitted with each tire was driven under the same conditions. There is an optimal value for the flex index, and if the flex index is too large, the handling performance will decrease due to insufficient tire rigidity. Handling performance is also standardized with Example 1 set to "100". In the handling performance evaluation test, each tire was fitted to a 4-stroke motorcycle with a displacement of 1300cc and rims of MT3.50×17 at the front and MT5.50×17 at the rear. The tire pressure was set to 250 kPa for the front and 290 kPa for the rear, and the road surface used for driving was dry asphalt. Each tire was manufactured under the same conditions, except for the sidewall manufacturing method and the thickness of the sidewall rubber.

[0027] As shown in Table 1, the evaluation results for "molding time" show that the comparative example was "long," while Examples 1-4 were "short." From these results, it can be seen that the molding time for green tires can be shortened according to the method according to this embodiment.

[0028] As shown in Table 1, the "flexure index" increases as the thickness of the sidewall rubber decreases. This does not depend on whether the sidewall rubber is assembled using the conventional method or attached to the floating ply 30. From these results, it can be seen that even with the method of this embodiment in which the sidewall rubber is formed by a rubber sheet 20 attached to the floating ply 30, it is possible to manufacture tires with performance equivalent to conventional tires.

[0029] As shown in Figure 1, the "handling stability performance" was highest in Example 3, where the sidewall rubber thickness was 2 mm, followed by Example 1, where the sidewall rubber thickness was 1 mm. Even in Example 2, where the sidewall rubber thickness was 0.5 mm, the "handling stability performance" was higher than in Example 4 and the Comparative Example, where the sidewall rubber thickness was 3 mm. From a comparison between the Comparative Example and Example 4, it can be seen that the "handling stability performance" does not depend on whether the sidewall rubber was assembled using the conventional method or attached to the floating ply 30. From these results, it can be seen that the preferred thickness of the rubber sheet 20 is 2 mm or less. More preferably, the thickness of the rubber sheet 20 is 1 mm or more and 2 mm or less. In the conventional method, it is difficult to make the sidewall rubber thinner than 3 mm, so the method according to this embodiment can improve the handling stability performance of the tire compared to the conventional method. In particular, since motorcycle tires often have load applied to the sides, the method according to this embodiment improves the feeling of contact with the ground and the ride comfort.

[0030] [Effects of the Embodiment] The following describes the effects and advantages that can be achieved by the tire manufacturing method according to this embodiment.

[0031] The tire manufacturing method according to this embodiment includes: an attachment step S20 of attaching a rubber sheet 20 to a floating ply 30; a winding body molding step S30 of forming a winding body 15 in which the carcass ply 40, the floating ply 30 with the rubber sheet 20 attached to it is formed into a cylindrical shape along the outer surface of a cylindrical molding former 110, and the carcass ply 40, the floating ply 30, and the rubber sheet 20 are arranged in this order from the radially inner side; and a step of deforming the axial central part of the winding body 15 radially outward to form the sidewall 17 of the green tire with the floating ply 30, the carcass ply 40, and the rubber sheet 20. According to this method, the sidewall rubber of the green tire is formed by the rubber sheet 20 attached to the floating ply 30 before molding. Therefore, there is no need to combine the sidewall rubber during molding. As a result, as shown in the embodiment, the time required to mold the green tire can be shortened.

[0032] In this embodiment, the first ply to which the rubber sheet 20 is attached includes a pair of floating prisms 30. The winding body molding process S30 includes a floating ply 30 molding process S31 in which the pair of floating prisms 30, each to which the rubber sheet 20 is attached, are molded into a cylindrical shape along the outer surface of the molding former 110; a carcass ply 40 molding process S32 in which a carcass ply 40 is placed on top of the pair of floating prisms 30 and molded into a cylindrical shape along the outer surface of the molding former 110; and a bead molding process S33 in which the axial ends of the carcass ply 40 are wound up around the bead core 50 to form a pair of bead portions 16. In the floating ply 30 molding process S31, the pair of floating prisms 30 are arranged so as to be separated in the axial direction of the molding former 110, and the rubber sheet 20 is positioned radially inward of the molding former 110. In the bead forming process S33, the pair of floating plies 30 and rubber sheets 20 are turned inside out so that the rubber sheets 20 face radially outward by winding both axial ends of the carcass plies 40 around the bead core 50. In this way, a wound body 15 can be formed in which the carcass plies 40, floating plies 30, and rubber sheets 20 are arranged in this order from radially inward.

[0033] The first ply to which the rubber sheet 20 is attached does not necessarily have to include a pair of floating plies 30; for example, it may be a single ply. In that case, for example, after rolling up both ends of the carcass ply 40 to form the bead portion 16, the first ply to which the rubber sheet 20 is attached may be placed on top from the outside. The rubber sheet 20 also does not necessarily have to be composed of a pair; for example, the rubber sheet 20 may be a single sheet.

[0034] In this embodiment, the rubber sheet 20 is configured to cover the outside of the bead portion 16. As a result, the outside of the bead portion is protected by rubber in both the green tire and the finished tire.

[0035] The method according to this embodiment includes a rubber sheet molding step S10 in which the rubber sheet 20 is formed by calendering. By forming the rubber sheet 20 by calendering, a thin rubber sheet 20 can be obtained, and the equipment can be standardized with molding equipment such as inner liners.

[0036] In this embodiment, the thickness of the rubber sheet 20 is 2 mm or less. This method, as described in the description of the embodiment, can improve the handling stability of the tire. Furthermore, in this embodiment, the rubber sheet 20 is attached to the floating ply 30. Therefore, the thin rubber sheet 20, which is easily stretched during molding on its own, can be made less prone to stretching by the support of the floating ply 30. If the rubber sheet 20 is stretched during molding, the tire quality becomes unstable. According to the method of this embodiment, such a situation can be suppressed and the tire quality can be stabilized.

[0037] In this embodiment, the tire is a motorcycle tire. As mentioned above, motorcycle tires often have load applied to the sides, so the method according to this embodiment particularly improves the feeling of contact with the road and the ride comfort.

[0038] [Other embodiments] A tire manufacturing method according to one embodiment has been described above. However, the tire manufacturing method of the present invention is not limited to the above-described embodiment unless otherwise specified. For example, in the above-described embodiment, two layers of ply were used, but three or more layers may be used.

[0039] Other steps may be added to the above-mentioned steps as appropriate. Some of the above-mentioned steps may be omitted as appropriate. The order of the steps may be changed as appropriate, unless otherwise specified and as long as it is possible to do so.

[0040] The various embodiments and modifications described herein can be combined as appropriate, provided that they do not interfere with one another. This specification includes, but is not limited to, the following inventions.

[0041] The present invention (1) includes the steps of: attaching a sheet-like rubber member to a first ply; forming a cylindrical shape along the outer surface of a cylindrical molding former with the second ply and the first ply with the rubber member attached, thereby forming a wound body in which the second ply, the first ply, and the rubber member are arranged in that order from the radially inner side; and deforming the axial central part of the wound body radially outward to form the sidewall of a green tire with the first ply, the second ply, and the rubber member.

[0042] The present invention (2) is a method for manufacturing a tire as described in the present invention (1), wherein the first ply includes a pair of floating plies. The step of forming a wound body includes the steps of forming a pair of floating plies, each with a rubber member attached, into a cylindrical shape along the outer surface of a molding former, arranging the pair of floating plies so that they are separated in the axial direction of the molding former and the rubber members are on the radially inner side of the molding former; overlapping a second ply with the pair of floating plies and forming it into a cylindrical shape along the outer surface of the molding former; and winding both axial ends of the second ply around the bead core to form a pair of bead portions and turning the pair of floating plies and rubber members inside out so that the rubber members are on the radially outer side.

[0043] The present invention (3) is a method for manufacturing a tire as described in the present invention (2), wherein the rubber member is configured to cover the outside of the bead portion.

[0044] The present invention (4) is a method for manufacturing a tire according to any one of the present inventions (1) to (3), further comprising the step of forming a rubber member by calendering.

[0045] Invention (5) is a method for manufacturing a tire according to any one of Inventions (1) to (4), wherein the thickness of the rubber material is 2 mm or less.

[0046] The present invention (6) is a method for manufacturing a tire according to any one of the present inventions (1) to (5), wherein the tire is a tire for a motorcycle. [Explanation of Symbols]

[0047] 15 coiled body 16 Bead section 17 Sidewall 20 Rubber sheet (rubber material) 30 Floating ply (1st ply) 40 Carcass ply (2nd ply) 50 Bead Core 100 Rubber sheet molding machine 110 Molding Former S10 Rubber sheet molding process S20 Application Process S30 Winding process S31 Floating ply molding process S32 Carcass ply molding process S33 Bead forming process S40 Expansion process

Claims

1. A step of attaching a sheet-like rubber material to the first ply, A step of forming a wound body in which the second ply and the first ply to which the rubber member is attached are formed into a cylindrical shape along the outer surface of a cylindrical molding former, and the second ply, the first ply, and the rubber member are arranged in this order from the radially inner side, The process includes deforming the axial central portion of the winding body radially outward to form the sidewall of the green tire with the first ply, the second ply, and the rubber member, The aforementioned first ply includes a pair of floating plies, The process of forming the aforementioned wound body is as follows: A step of forming the pair of floating plies, each to which the rubber member is attached, into a cylindrical shape along the outer circumferential surface of the molding former, and arranging the pair of floating plies so that they are separated in the axial direction of the molding former and the rubber members are located radially inward of the molding former, The process involves overlapping the second ply onto the pair of floating plies and forming it into a cylindrical shape along the outer surface of the molding former, The process includes the step of winding both axial ends of the second ply around the bead core to form a pair of bead portions, and turning the pair of floating ply and the rubber member inside out so that the rubber member is on the radially outer side, In the step of attaching the rubber member to the first ply, the pair of floating plies are attached to the rubber member such that they each protrude to the outside of the rubber member. In the aforementioned winding body, the protruding portion of the floating ply extends further inward in the axial direction of the winding body than the rubber member. In the sidewall of the aforementioned green tire, the protruding portion of the floating ply extends radially outward from the rubber member of the winding body. Tire manufacturing method.

2. The rubber member is configured to cover the outside of the bead portion. The method for manufacturing a tire according to claim 1.

3. The process further includes forming the rubber member by calendering. The method for manufacturing a tire according to claim 1.

4. The thickness of the rubber member is 2 mm or less. The method for manufacturing a tire according to claim 1.

5. The tire is a motorcycle tire. The method for manufacturing a tire according to claim 1.

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