Rubber member molding device and molding method

Abstract

To make it possible to control a direction in which a cord extends in a molding apparatus and molding method for a cylindrical rubber member having the cord.SOLUTION: An apparatus for winding a rubber sheet GS having a plurality of cords 51 to mold a cylindrical rubber member 50 includes: a first drum 81 around which the rubber sheet GS is wound; a second drum 82 that is arranged concentrically with the first drum 81 and around which the rubber sheet GS is wound; a first drive unit 84 that relatively rotates the first drum 81 and the second drum 82 about an axis; a first fixing part 91 that fixes a portion of the rubber sheet GS to an outer peripheral surface of the first drum 81; and a second fixing part 92 that fixes a portion of the rubber sheet GS to the outer peripheral surface of the second drum 82.SELECTED DRAWING: Figure 9C

Description

[Technical Field]

[0001] The present invention relates to a molding device and molding method for rubber members that constitute a pneumatic tire, and to a pneumatic tire. [Background technology]

[0002] A pneumatic tire used on a vehicle includes a tread that contacts the ground, a pair of sidewalls extending radially inward from both axial sides of the tread, and beads disposed at the radially inner ends of each sidewall. A belt layer is provided radially inward of the tread, and a carcass is provided radially inward of the belt layer and axially inward of the sidewalls, spanning between the pair of beads. The carcass has a carcass ply in which multiple carcass cords made of organic fibers or the like are arranged in parallel.

[0003] In the manufacturing process of pneumatic tires, a cylindrical carcass ply is formed by winding a rubber sheet in which carcass cords are embedded around a drum of a forming device (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-109348 Summary of the Invention [Problem to be solved by the invention]

[0005] The carcass ply forms the framework of a pneumatic tire, and the direction in which the carcass cords extend determines the type of tire, such as radial or bias, and determines performance such as durability and rigidity. If the direction in which the carcass cords extend can be controlled during the carcass ply molding stage, it may be possible to easily realize a pneumatic tire with desired performance.

[0006] The present disclosure aims to enable control of the extension direction of cords when molding a cylindrical rubber member having cords, such as a carcass ply, and also aims to provide a pneumatic tire in which the extension direction of the carcass cords is controlled. [Means for solving the problem]

[0007] (1) The present disclosure provides an apparatus for forming a cylindrical rubber member by winding a rubber sheet having a plurality of cords, a first drum around whose outer periphery the rubber sheet is wound; a second drum arranged concentrically with the first drum and around whose outer periphery the rubber sheet is wound; a first driving unit that rotates the first drum and the second drum relatively around an axis; a first fixing portion that fixes a portion of the rubber sheet to the outer peripheral surface of the first drum; and a second fixing portion that fixes a portion of the rubber sheet to the outer peripheral surface of the second drum.

[0008] With this configuration, when the rubber sheet is wound around the first drum and the second drum and fixed to the first drum and the second drum by the first and second fixing parts, the direction in which the cord extends can be changed between the portion of the rubber sheet wound around the first drum and the portion of the rubber sheet wound around the second drum, making it possible to control the direction in which the cord extends according to the desired tire performance.

[0009] (2) Preferably, the molding device includes a third drum that is arranged concentrically with the first drum on the opposite side of the axial direction from the second drum, and around which the rubber sheet is wound; a second drive unit that rotates the first drum and the third drum relatively around their axes; and a third fixing portion that fixes a portion of the rubber sheet to the outer peripheral surface of the third drum. With this configuration, for example, when the rubber member is a carcass ply that is arranged across the tread portion and a pair of sidewall portions of a pneumatic tire, it is possible to control the direction in which the cords extend in each of the three regions of the tread portion and the pair of sidewall portions.

[0010] (3) Preferably, the second driving section rotates the third drum relatively in a direction opposite to a direction of relative rotation of the second drum with respect to the first drum. According to this configuration, when the rubber member is a carcass ply, for example, it is possible to control the directions in which the carcass cords extend in the pair of sidewall portions to be opposite to each other.

[0011] (4) Preferably, a first detection unit that detects the amount of relative rotation between the first drum and the second drum; The device further includes a second detection unit that detects the amount of relative rotation between the first drum and the third drum. According to this configuration, the amount of rotation of the second drum and the amount of rotation of the third drum relative to the first drum are detected by the first and second detection units, respectively, and the direction in which the cord extends can be accurately controlled.

[0012] (5) Preferably, the second drum and the third drum are configured to be expandable and contractible in the radial direction. According to this configuration, when the rubber member is a carcass ply, for example, the diameter of both axial ends of the cylindrically formed carcass ply can be reduced, making it easier to insert the carcass ply into the bead.

[0013] (6) The molding method of the present disclosure is a method for molding a cylindrical rubber member by winding a rubber sheet having a plurality of cords, a step of winding the rubber sheet around a first drum and a second drum provided concentrically with the first drum; a step of fixing a portion of the rubber sheet to each of an outer peripheral surface of the first drum and an outer peripheral surface of the second drum; and rotating the first drum and the second drum relatively around their axes.

[0014] With this configuration, when the rubber sheet is wound around the first drum and the second drum and the first drum and the second drum are rotated relative to each other while the rubber sheet is fixed to the first drum and the second drum, the direction in which the cord extends can be changed between the portion of the rubber sheet wound around the first drum and the portion of the rubber sheet wound around the second drum, making it possible to control the direction in which the cord extends depending on the desired tire performance.

[0015] (7) The pneumatic tire of the present disclosure comprises a tread that contacts the ground, a pair of sidewalls extending radially inward from both axial ends of the tread, a belt arranged radially inward of the tread, and a carcass arranged radially inward of the belt and axially inward of the sidewall, wherein the belt comprises a belt ply having a plurality of belt cords, the carcass comprises a carcass ply having a plurality of carcass cords, the belt cords are arranged at an angle relative to the circumferential direction, and the carcass cords are arranged radially inside the belt at an angle in the opposite direction to the belt cords relative to the circumferential direction, and are arranged radially inside the sidewall in the axial direction.

[0016] With this configuration, the carcass cords are arranged radially on the axially inner side of the sidewall, making it possible to construct a pneumatic tire with performance substantially equivalent to that of a radial tire. Also, on the radially inner side of the tread, the carcass cords are inclined relative to the circumferential direction, and the belt cords 61 of the belt ply that overlap them are inclined in the opposite direction to the carcass cords 51. Therefore, the twist of the carcass ply, in which the carcass cords are bias-arranged on the radially inner side of the tread, is counteracted by the belt ply, making it possible to provide a pneumatic tire with a stable shape.

[0017] (8) Preferably, the belt is made up of one belt ply, and the carcass is made up of one carcass ply. This simplifies the structure of the pneumatic tire and reduces its weight. [Effects of the Invention]

[0018] According to the present invention, the directionality of the cords of the cylindrical rubber member can be controlled. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a pneumatic tire. [Figure 2] FIG. 2 is a schematic perspective view showing an arrangement of carcass cords in a carcass ply. [Figure 3] FIG. 3 is a development view of the carcass ply. [Figure 4] FIG. 4 is a schematic perspective view showing a carcass ply forming device. [Figure 5] FIG. 5 is a schematic side view showing a carcass ply forming device. [Figure 6] FIG. 6 is a control block diagram showing a carcass ply forming device. [Figure 7] FIG. 7 is a schematic cross-sectional view showing the expansion / contraction mechanism of the second and third drums. [Figure 8] FIG. 8 is a schematic side view showing the expansion / contraction mechanism of the second and third drums. [Figure 9A] FIG. 9A is a schematic perspective view showing a carcass ply forming process. [Figure 9B] FIG. 9B is a schematic perspective view showing a carcass ply forming process. [Figure 9C] FIG. 9C is a schematic perspective view showing a carcass ply forming process. [Figure 9D] FIG. 9D is a schematic perspective view showing the carcass ply forming process. [Figure 10] FIG. 10 is a development view of a carcass ply according to a modified example. [Figure 11] FIG. 11 is a development view of a rubber member according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. [Configuration of pneumatic tires] 1 is a cross-sectional view showing an example of a pneumatic tire. In this specification, the direction parallel to the rotation axis of the pneumatic tire 1 is referred to as the "axial direction" or "width direction," the direction perpendicular to the rotation axis is referred to as the "radial direction," and the direction in which the pneumatic tire 1 rotates (the direction along the outer peripheral surface) is referred to as the "circumferential direction." Furthermore, the "axially inner direction" refers to the direction from the outer surface of the pneumatic tire 1 toward the inner surface in the axial direction.

[0021] In FIG. 1, a pneumatic tire 1 includes a tread 2, sidewalls 3, beads 4, a belt 6, a carcass 5, and an inner liner 7. The tread 2 is the part that comes into contact with the ground. The sidewalls 3 extend radially inward from both axial ends of the tread 2. The beads 4 are located at the radially inner ends of each sidewall 3. Each bead 4 includes a ring-shaped bead core 41 and a bead apex rubber 42.

[0022] The belt 6 is disposed radially inside the tread 2. The belt 6 has a belt ply 60. The belt ply 60 includes a plurality of belt cords 61 and a topping rubber 62 that covers the belt cords 61 (see FIG. 3). The belt cords 61 are disposed at an angle with respect to the circumferential direction of the pneumatic tire 1. For example, a steel cord is used as the belt cord 61 in this embodiment. The belt cord 61 may also be an organic fiber cord. The belt 6 in this embodiment is made up of one belt ply 60.

[0023] The carcass 5 is laid between the bead cores 41 on both sides in the axial direction. The carcass 5 is located radially inward of the belt 6 and axially inward of the sidewall 3. The carcass 5 has a carcass ply 50. The carcass 5 of this embodiment consists of one carcass ply 50. At both ends of the carcass ply 50, turned-up portions 53 are formed that are turned-up from the axially inner side to the axially outer side around the bead core 4a. An inner liner 7 is attached to the inner surface of the carcass 5.

[0024] In the following description, the axial region of the tread 2 may be referred to as the "tread portion" of the pneumatic tire 1, and the radial region of the sidewall 3 may be referred to as the "sidewall portion" of the pneumatic tire 1.

[0025] Fig. 2 is a schematic perspective view showing the arrangement of carcass cords in a carcass ply, and Fig. 3 is a development view of the carcass ply. The carcass ply 50 includes a plurality of carcass cords 51 and a topping rubber 52 covering the carcass cords 51. The carcass cords 51 are made of, for example, organic fiber cords such as nylon, polyester, or rayon. The carcass cords 51 may be steel cords. The carcass cords 51 are arranged at an inclination with respect to the circumferential direction in a portion R1 located radially inward of the tread 2. More specifically, the carcass cords 51 are arranged at an inclination with respect to the circumferential direction in the portion R1 in the opposite direction to the belt cords 61. The carcass cords 51 are arranged along the radial direction in a portion R2 located axially inward of the sidewall 3. Therefore, the pneumatic tire of this embodiment has performance, such as rigidity and springiness, equivalent to that of a radial tire in the sidewall portion. Furthermore, in the pneumatic tire of this embodiment, the carcass cords 51 and the belt cords 61 are arranged at an inclination with respect to the circumferential direction in the tread portion, so that the twist of the carcass ply 50 is counteracted by the belt ply 60, thereby suppressing ply steer.

[0026] [Carcass molding device] FIG. 4 is a schematic perspective view showing a carcass ply molding device. FIG. 5 is a schematic side view showing a carcass ply molding device. FIG. 6 is a control block diagram showing a carcass ply molding device. More specifically, FIGS. 4 to 6 show a molding device that wraps a rubber sheet that constitutes an inner liner and a rubber sheet that constitutes a carcass ply together to form them into a cylindrical shape, and then attaches beads to mold an intermediate product (so-called first cover) of a green tire (a tire before vulcanization). However, this embodiment focuses only on the carcass ply, and the molding process thereof will be described in detail.

[0027] 4, the forming device 80 has a first drum 81, a second drum 82, and a third drum 83. A rubber sheet GS (see FIG. 5) that forms the carcass ply 50 is wound around the outer peripheral surfaces of the first drum 81, the second drum 82, and the third drum 83.

[0028] The first drum 81, the second drum 82, and the third drum 83 are each formed in a substantially cylindrical shape. The first drum 81, the second drum 82, and the third drum 83 are arranged concentrically. The second drum 82, the first drum 81, and the third drum 83 are arranged side by side in this order in the axial direction. The second drum 82 and the third drum 83 are each configured to be movable away from the first drum 81 in the axial direction.

[0029] The first drum 81, the second drum 82, and the third drum 83 are configured to be rotatable relative to one another about their respective axes. The molding device 80 has a first drive unit 84 that rotationally drives the second drum 82, and a second drive unit 85 that rotationally drives the third drum 83. The first drive unit 84 and the second drive unit 85 are configured by, for example, electric motors.

[0030] The molding device 80 has a first detection unit 86 and a second detection unit 87. The first detection unit 86 detects the amount of relative rotation of the second drum 82 with respect to the first drum 81. The second detection unit 87 detects the amount of relative rotation of the second drum 82 with respect to the first drum 81. For example, a rotary encoder is used for the first detection unit 86 and the second detection unit 87.

[0031] As shown in FIG. 5, the molding device 80 has a first fixing portion 91, a second fixing portion 92, and a third fixing portion 93 that fix the rubber sheet GS that constitutes the carcass ply 50 to the outer circumferential surfaces of the first to third drums 81 to 83. The first to third fixing portions 91 to 93 each include a plurality of pressure plates 91a to 93a and drive portions 91b to 93b that drive the pressure plates 91a to 93a. The pressure plates 91a to 93a are arranged radially outward of the first to third drums 81 to 83. Each pressure plate 91a to 93a is formed in an arc shape that conforms to the outer circumferential surface of the rubber sheet wound around the first to third drums 81 to 83. The pressure plates 91a to 93a are arranged at intervals in the circumferential direction of the first to third drums 81 to 83.

[0032] The drive units 91b to 93b of the first to third fixed units 91 to 93 move the pressure plates 91a to 93a toward or away from the first to third drums 81 to 83. The drive units 91b to 93b are configured by, for example, a fluid pressure cylinder such as an air cylinder, a screw-type mechanical cylinder, or an expandable actuator such as an electromagnetic solenoid.

[0033] Figure 7 is a schematic cross-sectional view showing the expansion / contraction mechanism of the second and third drums, and Figure 8 is a schematic side view showing the expansion / contraction mechanism of the second and third drums. The second drum 82 and the third drum 83 are each formed by arranging a plurality of segments 82a, 83a in the circumferential direction, and the outer diameters of the second and third drums 82, 83 are increased or decreased by moving each segment 82a, 83a in the radial direction. The forming device 80 is equipped with an expansion / contraction mechanism 95 that increases or decreases the outer diameters of the second and third drums 82, 83.

[0034] 7, shoe members 82b, 83b, each having a substantially triangular shape in front view, are provided on the inner surfaces of the segments 82a, 83a. The expansion / contraction mechanism 95 includes an actuating member 95a having a conical guide surface 95a1 with which the shoe members 82b, 83b come into contact, and a drive unit 95b that moves the actuating member 95a in the axial direction. The drive unit 95b is configured with an expandable actuator, such as a fluid pressure cylinder such as an air cylinder, a screw-type mechanical cylinder, or an electromagnetic solenoid.

[0035] As shown in FIG. 6, the molding apparatus 80 is equipped with a control device 90. The control device 90 is composed of a microcomputer or the like equipped with a calculation unit such as a CUP and a storage unit such as RAM and ROM. The control device 90 performs a predetermined function by the calculation unit executing a program installed in the storage unit. The control device 90 has a function of controlling the operation of the first drive unit 84, the second drive unit 85, the first fixing unit 91, the second fixing unit 92, the third fixing unit 93, and the expansion / contraction mechanism 95. The control device 90 also receives detection results from the first detection unit 86 and the second detection unit 87 and uses them to control the operation of the first and second drive units 84 and 85.

[0036] 9A to 9D are schematic perspective views showing the carcass molding process. The carcass molding process will be described below with reference to FIGS. 9A to 9D. 9A, a rubber sheet GS in which a plurality of carcass cords 51 are covered with a topping rubber 52 is wound around the outer circumferential surfaces of the first to third drums 81 to 83. The plurality of carcass cords 51 are arranged at an angle with respect to the circumferential direction of the first to third drums 81 to 83.

[0037] In the second step shown in FIG. 9B , the presser plates 91a to 93a of the first to third fixing portions 91 to 93 press the outer peripheral surface of the rubber sheet GS wound around the first to third drums 81 to 83 from the radially outer side. The first presser plate 91a presses the rubber sheet GS in a widthwise range that is substantially the same as the width of the first drum 81. The second presser plate 92a presses the rubber sheet GS at one axial end of the rubber sheet GS in a widthwise range that is smaller than the width of the second drum 82. The third presser plate 93a presses the rubber sheet GS at the other axial end of the rubber sheet GS in a widthwise range that is smaller than the width of the third drum 83. As a result, the rubber sheet GS is sandwiched between the first to third drums 81 to 83 and the first to third fixing portions 91 to 93, and is thereby fixed to the first to third drums 81 to 83.

[0038] 9C , the first driver 84 and the second driver 85 are driven, causing the second drum 82 to rotate in the direction of arrow a relative to the stationary first drum 81, and the third drum 83 to rotate in the direction of arrow b opposite to arrow a. At this time, the second fixed part 92 also rotates in the same direction a as the second drum 82 by the same rotational amount. The third fixed part 93 also rotates in the same direction b as the third drum 83 by the same rotational amount.

[0039] The rotation amounts of the second drum 82 and the third drum 83 are detected by first and second detection units 86 and 87, respectively. When the detected rotation amounts reach a predetermined value, the first and second drive units 84 and 85 stop. The rotation amounts of the second and third drums 82 and 83 are the amounts at which the carcass cords 51 of the rubber sheet GS wound around the second and third drums 82 and 83 become approximately parallel to the axial centers of the second and third drums 82 and 83.

[0040] In a fourth step shown in FIG. 9D , the expansion / contraction mechanism 95 is driven to reduce the outer diameters of the second drum 82 and the third drum 83. As a result, the outer diameter of the rubber sheet GS wound around the second drum 82 and the third drum 83 is also reduced. Thereafter, the second drum 82 and the third drum 83 are removed from the rubber sheet GS, and instead, the beads 4 are positioned on the outer peripheral surface of the rubber sheet GS by a bead transfer (not shown). Then, both axial ends of the rubber sheet GS are folded back by a turn-up bladder (not shown), and portions that become the folded back portions 53 shown in FIG. 1 are formed. The intermediate green tire product thus formed is transferred to an application device for the sidewall 3 and an application device for the tread 2, where the final green tire is molded.

[0041] In the above embodiment, the molding device 80 for the carcass ply 50 has a first drum 81, a second drum 82, and a third drum 83, and the rubber sheet GS constituting the carcass ply 50 is wound around the outer peripheral surfaces of these drums. The molding device 80 includes first to third fixing units 91 to 93 that fix the rubber sheet GS to the first to third drums 81 to 83, respectively, and first and second driving units 84, 85 that rotate the second drum 82 and the third drum 83 relative to the first drum 81. This makes it possible to change the direction in which the carcass cords 51 extend between the axial center portion and both axial ends of the rubber sheet GS. In other words, it is possible to control the direction in which the carcass cords 51 extend. In the above embodiment, the carcass cords 51 extend radially in the sidewall portion of the pneumatic tire 1, and the carcass cords 51 are inclined with respect to the circumferential direction in the tread portion.

[0042] The pneumatic tire 1 of the above embodiment includes a carcass 5 consisting of one carcass ply 50 and a belt 6 consisting of one belt ply 60. The carcass cords 51 in the tread portion of the pneumatic tire 1 and the belt cords 61 of the belt ply 60 are inclined in opposite directions relative to the circumferential direction. Therefore, the cords 51, 61 can cross each other using one carcass ply 50 and one belt ply 60. Conventional bias tires require overlapping multiple carcass plies having carcass cords inclined in opposite directions relative to the circumferential direction, and breakers are further provided on the outer sides as needed. Conventional radial tires require overlapping multiple belt plies having belt cords inclined in opposite directions relative to the circumferential direction on the radially outer side of the carcass. In contrast, the tire of the present embodiment can achieve a cord arrangement structure that suppresses plysteer simply by overlapping one carcass ply 50 and one belt ply 60, thereby simplifying the structure of the pneumatic tire 1 and reducing its weight.

[0043] [Variations] FIG. 10 is a development view of a carcass ply according to a modified example. The direction in which the carcass cords 51 of the carcass ply 50 extend is not limited to the above embodiment and can be modified into various forms. For example, as shown in Fig. 8, the carcass cords 51 can be oriented perpendicular to the circumferential direction in a portion R1 located radially inside the tread 2, and can be inclined in opposite directions relative to the radial direction in two portions R2 located axially inside the pair of sidewalls 3. Alternatively, the carcass cords 51 can be oriented perpendicular to the circumferential direction in the portion R1, and can be inclined in the same direction relative to the radial direction in the two portions R2.

[0044] FIG. 11 is a development view of a rubber member according to a modified example. The rubber member molding device 80 of the present disclosure may omit the third drum 83 and the corresponding third fixing unit 93, second driving unit 85, second detection unit 87, etc., of the above embodiment. Furthermore, the rubber member molded by the molding device 80 is not limited to a carcass ply. In a modified example shown in FIG. 11 , the direction in which the cords of the rubber sheets wound around the first drum 81 and the second drum 82 extend can be changed by rotating the first drum 81 and the second drum 82 relative to each other. For example, the cord 96 of the portion R3 wound around the first drum 81 and the cord 96 of the portion R4 wound around the second drum 82 can be inclined in opposite directions relative to each other with respect to the circumferential direction. Alternatively, the cord 96 of the portion wound around one of the first and second drums 81 and 82 can be arranged parallel to the axis, and the cord 96 of the portion wound around the other drum can be inclined relative to the circumferential direction.

[0045] The rubber member molding device 80 of the present disclosure may be equipped with four or more drums, as long as they include drums corresponding to the first drum 81 and the second drum 82, or drums corresponding to the first to third drums 81 to 83. Therefore, when the molding device 80 is equipped with four or more drums, it is sufficient that at least two of the drums are configured to be rotatable relative to one another.

[0046] [Effects of this embodiment] The molding device 80 of the above embodiment includes a first drum 81 around which a rubber sheet GS is wound, a second drum 82 that is arranged concentrically with the first drum 81 and around which the rubber sheet GS is wound, a first drive unit 84 that rotates the first drum 81 and the second drum 82 relative to each other about their axes, a first fixing unit 91 that fixes a portion of the rubber sheet GS to the outer peripheral surface of the first drum 81, and a second fixing unit 92 that fixes a portion of the rubber sheet GS to the outer peripheral surface of the second drum 82. With this configuration, when the rubber sheet GS is wound around the first drum 81 and the second drum 82 and the first drum 81 and the second drum 82 are rotated relative to each other with the rubber sheet GS fixed to the first drum 81 and the second drum 82 by the first and second fixing units 91, 92, the direction in which the cord 51 extends can be changed between the portion wound around the first drum 81 and the portion wound around the second drum 82. Therefore, it is possible to control the direction in which the cord 51 extends depending on the desired tire performance.

[0047] The molding device 80 of the above embodiment includes a third drum 83 that is arranged concentrically with the first drum 81 on the axially opposite side of the second drum 82 and has a rubber sheet GS wound around its outer periphery, a second drive unit 85 that rotates the first drum 81 and the third drum 83 relatively about the axis, and a third fixing unit 93 that fixes a portion of the rubber sheet GS to the outer periphery of the third drum 83. With this configuration, for example, when the rubber member is a carcass ply 50, it is possible to control the direction in which the cords 51 extend in each of the three regions: the tread portion and the pair of sidewall portions.

[0048] In the above embodiment, the second driving unit 85 rotates the third drum 83 relative to the first drum 81 in the direction opposite to the relative rotation direction of the second drum 82. This allows the directionality of the cords 51 arranged in the pair of sidewall portions to be changed to opposite directions when the rubber member is the carcass ply 50.

[0049] The forming device 80 of the above embodiment includes a first detection unit 86 that detects the amount of relative rotation between the first drum 81 and the second drum 82, and a second detection unit 87 that detects the amount of relative rotation between the first drum 81 and the third drum 83. Therefore, the amount of rotation of the second drum 82 and the amount of rotation of the third drum 83 relative to the first drum 81 can be detected by the first and second detection units 86, 87, and the direction in which the cord 51 extends can be accurately controlled.

[0050] In the above embodiment, the second drum 82 and the third drum 83 are configured to be expandable and contractible in the radial direction. Therefore, when the rubber member is the carcass ply 50, the diameters of both axially opposite sides can be reduced, making it easier to insert the beads 4.

[0051] The pneumatic tire 1 of the above embodiment includes a tread 2 that contacts the ground, a pair of sidewalls 3 extending radially inward from both axial ends of the tread 2, a belt 6 arranged radially inside the tread 2, and a carcass 5 arranged radially inside the belt 6 and axially inside the sidewalls 3, the belt 6 includes a belt ply 60 having a plurality of belt cords 61, the carcass 5 includes a carcass ply 50 having a plurality of carcass cords 51, the belt cords 61 are arranged inclined with respect to the circumferential direction, and the carcass cords 51 are arranged radially inside the belt 6 inclined in the opposite direction to the belt cords with respect to the circumferential direction, and are arranged radially inside the axial inside of the sidewalls 3. With this configuration, the carcass cords 51 are arranged radially inside the axial inside of the sidewalls 3, so that a pneumatic tire 1 having substantially the same performance as a radial tire can be configured. Furthermore, on the radially inner side of the tread 2, the carcass cords 51 are inclined relative to the circumferential direction, and the belt cords 61 of the belt ply 60 that overlap them are inclined in the opposite direction to the carcass cords 51. Therefore, in the tread portion, the twist of the carcass ply 50 in which the carcass cords 51 are bias-arranged is counteracted by the belt ply 60, thereby providing a pneumatic tire that can suppress ply steer.

[0052] In the pneumatic tire 1 of the above embodiment, the belt 6 is made up of one belt ply 60, and the carcass 5 is made up of one carcass ply 50. This simplifies the structure of the pneumatic tire and reduces its weight.

[0053] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above specific embodiments and can be modified and implemented in various ways. [Explanation of symbols]

[0054] 1: Pneumatic tires 2: Tread 3: Sidewall 5: Carcass 6: Belt 50: Carcass ply 51: Carcass Code 60: Belt ply 61: Belt cord 80: Molding equipment 81: First drum 82: 2nd drum 83: Third drum 84: First drive unit 85: Second drive unit 86: First detection unit 87: Second detection unit 91: 1st fixed part 92:Second fixed part 93:Third fixed part 95: Scaling mechanism 96: Code GS: Rubber sheet

Claims

1. An apparatus for forming a carcass ply, which is a cylindrical rubber member, by winding a rubber sheet having a plurality of cords arranged parallel to each other, a first drum around which a first portion of the rubber sheet to be disposed in a tread portion of a tire is wound; a second drum that is concentrically disposed with the first drum and around which a second portion of the rubber sheet is wound, the second portion being axially outward of the first portion and disposed in one sidewall portion of the tire; a third drum that is arranged coaxially with the first drum on the opposite side of the second drum in the axial direction, and around which a third portion of the rubber sheet is wound, the third portion being axially outward of the first portion and arranged on the other sidewall portion of the tire; a first driving unit that rotates the first drum and the second drum relatively around an axis; a second drive unit that rotates the first drum and the third drum relatively around their axes; a first fixing portion that fixes the first portion of the rubber sheet to the outer peripheral surface of the first drum; a second fixing portion that fixes the second portion of the rubber sheet to the outer peripheral surface of the second drum; a third fixing portion that fixes the third portion of the rubber sheet to the outer peripheral surface of the third drum, A rubber member molding device that changes the direction of the cords in the first portion and the cords in the second portion and the third portion in the rubber sheet by rotating the second drum and the third drum relative to the first drum using the first drive unit and the second drive unit.

2. The rubber member molding device according to claim 1 , wherein the second driving unit rotates the third drum relative to the first drum in a direction opposite to a direction of relative rotation of the second drum relative to the first drum.

3. a first detection unit that detects a relative rotation amount between the first drum and the second drum; The rubber member molding device according to claim 1 or 2, further comprising: a second detection unit that detects a relative rotation amount between the first drum and the third drum.

4. The rubber member molding device according to any one of claims 1 to 3, wherein the second drum and the third drum are configured to be expandable and contractible in a radial direction.

5. A method for forming a carcass ply, which is a cylindrical rubber member, by winding a rubber sheet having a plurality of cords arranged parallel to each other, comprising: a step of winding a first portion of the rubber sheet to be disposed in a tread portion of the tire around a first drum, winding a second portion of the rubber sheet to be disposed axially outward of the first portion and in one sidewall portion of the tire around a second drum provided concentrically with the first drum, and winding a third portion of the rubber sheet to be disposed axially outward of the first portion and in the other sidewall portion of the tire around a third drum provided coaxially with the first drum on the opposite side of the second drum in the axial direction; a step of fixing a portion of the rubber sheet to each of an outer peripheral surface of the first drum, an outer peripheral surface of the second drum, and an outer peripheral surface of the third drum; rotating the first drum and the second drum relative to each other about their respective axes, and rotating the first drum and the third drum relative to each other about their respective axes; A method for molding a rubber member, wherein the direction of the cords in the first portion and the cords in the second and third portions in the rubber sheet is changed by rotating the second drum and the third drum relative to the first drum.

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