Method for manufacturing pneumatic tires

Abstract

To provide a method for manufacturing a pneumatic tire that prevents a bead filler from falling down when a bead member is cooled.SOLUTION: A method for manufacturing a pneumatic tire comprises: a first step of forming an annular bead member by crimping a bead filler having a thickness that decreases toward the radially outer side of the bead core to the outer peripheral portion of the bead core; a second step of supporting the bead filler on the separator and placing the bead member so that the radial direction of the bead core is along the horizontal direction; and a third step of cooling the bead member.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a pneumatic tire. [Background technology]

[0002] A pneumatic tire includes an annular bead member embedded in a bead portion. The bead member is manufactured by press-fitting a bead filler formed with a generally triangular cross section onto the outer periphery of an annular bead core. In Patent Document 1, the manufactured bead member is supported by a separator on one side of the bead filler, and is erected so that the radial direction of the bead core is aligned with the up-down direction. By supporting the separator on one side of the bead filler, the bead filler is prevented from falling toward the one side.

[0003] However, when the bead member is cooled in an upright state, the bead filler may be deformed due to thermal contraction and peel off from the separator, causing the bead filler to fall toward the other side portion that is not supported by the separator. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-91162 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a method for manufacturing a pneumatic tire that prevents a bead filler from collapsing when a bead member is cooled. [Means for solving the problem]

[0006] The method for manufacturing a pneumatic tire of the present disclosure includes a first step of forming an annular bead member by pressing a bead filler, the thickness of which decreases radially outward from the bead core, onto the outer periphery of the bead core; a second step of supporting the bead filler on a separator and placing the bead member so that the radial direction of the bead core is aligned horizontally; and a third step of cooling the bead member. [Brief explanation of the drawings]

[0007] [Figure 1] A meridian cross-sectional view of an example of a pneumatic tire. [Figure 2] Cross-sectional view of a bead member [Figure 3A] Schematic cross-sectional view showing the crimping device before crimping [Figure 3B] Schematic cross-sectional view showing the crimping device after crimping [Figure 4] FIG. 10 is a cross-sectional view showing a state in which the bead member is placed. [Figure 5] FIG. 10 is a cross-sectional view showing a state in which stacked bead members are placed. [Figure 6] FIG. 10 is a plan view showing an example of a step of cooling the bead member. [Figure 7] 10 is a cross-sectional view showing an example of a step of erecting a bead member.

[0008] <Pneumatic tires> First, an example of a pneumatic tire manufactured by the manufacturing method according to the present embodiment will be described with reference to Fig. 1. Note that in each figure (as well as Figs. 2 to 7), the dimensional ratios in the drawing do not necessarily match the actual dimensional ratios, and the dimensional ratios between the drawings do not necessarily match either.

[0009] In Fig. 1, a first direction D1 indicates a tire axial direction D1 that is parallel to the tire rotation axis of a pneumatic tire (hereinafter also simply referred to as "tire") T, and a second direction D2 indicates a tire radial direction D2 that is the diameter direction of the tire T. In the tire radial direction D2, the inner side indicates the side closer to the tire rotation axis, and the outer side indicates the side farther from the tire rotation axis. The tire equatorial plane S is a plane that is perpendicular to the tire rotation axis and is located at the center of the tire axial direction D1 of the tire T, and the tire meridian plane is a plane that includes the tire rotation axis and is perpendicular to the tire equatorial plane S.

[0010] As shown in FIG. 1, the tire T includes a pair of bead portions 1, 1, a pair of sidewalls 2, 2 extending outward in the tire radial direction D2 from each of the pair of bead portions 1, 1, and a tread 3 continuing to the outer ends of each of the pair of sidewalls 2, 2 in the tire radial direction D2.

[0011] A carcass ply 4 is laid across the sidewall 2 and tread 3 between the pair of bead portions 1, 1. An inner liner 5 for maintaining air pressure is disposed on the inner peripheral side of the carcass ply 4. A belt layer 6 is disposed on the outer side of the carcass ply 4 in the tire radial direction D2 of the tread 3. Tread rubber 7 is disposed on the outer side of the tread 3 in the tire radial direction D2, and a tread pattern is formed.

[0012] An annular bead core 11 is embedded in the bead portion 1, and a bead filler 12 is disposed on the outer side of the bead core 11 in the tire radial direction D2. The member integrating the bead core 11 and the bead filler 12 is called a bead member 10. A chafer pad 8 is disposed between the bead filler 12 and the sidewall 2.

[0013] <Manufacturing method of pneumatic tires> Next, a method for manufacturing a pneumatic tire according to this embodiment will be described with reference to FIGS.

[0014] The tire T in FIG. 1 is manufactured through a tire component manufacturing process, a green tire manufacturing process, and a tire vulcanization process. The tire component manufacturing process is a process for manufacturing tire components such as tread rubber, sidewall rubber, carcass ply, inner liner, belt, and bead component 10. The green tire manufacturing process is a process for manufacturing a green tire by assembling the tire components on a building drum. The tire vulcanization process is a process for manufacturing a vulcanized tire by vulcanizing the green tire in a vulcanization mold.

[0015] The tire manufacturing method (tire constituent member manufacturing process) includes first to third steps for manufacturing the bead member 10. In this embodiment, the tire manufacturing method includes a fourth step of erecting the bead member 10, but is not limited to this.

[0016] [1st step] As shown in FIG. 2, in the first step, the bottom portion 12a of the bead filler 12 is pressure-bonded to the outer peripheral portion 11a of the bead core 11, thereby producing the bead member 10.

[0017] 2 (also in FIGS. 3A to 5 and 7), the third direction D3 indicates the radial direction D3 of the bead core 11. In the radial direction D3 of the bead core 11, the inner side indicates the side closer to the center of the bead core 11, and the outer side indicates the side farther from the center of the bead core 11 (the bead filler 12 side). The radial direction D3 may be the same direction as the tire radial direction D2.

[0018] The bead core 11 is an annular member formed by rubber-coating a bundle (not shown) such as a steel wire. The bead core 11 is formed to have a polygonal cross section. In this embodiment, the bead core 11 is formed to have a hexagonal cross section. The bead core 11 is inclined with respect to a direction perpendicular to the radial direction D3. Specifically, the bead core 11 is inclined inward in the tire radial direction D2 from the outer end to the inner end of the bead core 11 in the tire axial direction D1 (see FIG. 1). Note that the bead core 11 is not limited to the above.

[0019] The bead filler 12 is an annular member made of hard rubber. The bead filler 12 has a triangular cross section and is tapered toward the outside of the bead core 11 in the radial direction D3. The bead filler 12 includes a bottom portion 12a that is press-bonded to the bead core 11, a first side portion 12b and a second side portion 12c that extend outward from the bottom portion 12a along the radial direction D3, and a tip portion 12d that is located at the outer end in the radial direction D3. The bottom portion 12a is formed in a concave shape that follows the shape of the outer circumferential portion 11a of the bead core 11.

[0020] From the viewpoint of suppressing air infiltration between the bead filler 12 and the carcass ply 4 (see FIG. 1) during the green tire manufacturing process, it is preferable that the first side surface portion 12b is disposed on the inner side in the tire axial direction D1, and the second side surface portion 12c is disposed on the outer side in the tire axial direction D1. In this embodiment, the first side surface portion 12b and the second side surface portion 12c are formed in a linear shape, but this is not limited thereto. For example, the first side surface portion 12b and the second side surface portion 12c may be formed in a concave or convex curved shape.

[0021] The height H of the bead filler 12 is preferably 80 mm or more. This allows the chafer pad 8 in FIG. 1 to be made smaller. As a result, in the green tire building process, the band body including the carcass ply and chafer pad can be easily rolled up, and air can be prevented from getting between the bead filler 12 and other components. The height H is the dimension from the inner end of the bottom 12a to the tip 12d in the radial direction D3. The angle θ of the tip 12d is preferably 16 degrees or less, from the viewpoint of preventing air from getting into the green tire in the green tire building process. However, the bead filler 12 is not limited to the above.

[0022] The bead core 11 and the bead filler 12 are preferably crimped together when the temperature difference between the bottom 12a and the tip 12d of the bead filler 12 is 25°C or less. By reducing the temperature difference between the bottom 12a and the tip 12d, the difference in rigidity between them can be reduced. This makes it possible to prevent the bead filler 12 from collapsing after being crimped to the bead core 11.

[0023] Furthermore, the bead core 11 and the bead filler 12 are preferably crimped together when the temperature of the tip 12d of the bead filler 12 is 39°C or higher. By increasing the temperature of the tip 12d, the difference in rigidity due to the temperature difference between the bottom 12a and the tip 12d can be reduced. This makes it possible to prevent the bead filler 12 from collapsing after being crimped to the bead core 11. The temperature of the tip 12d of the bead filler 12 during crimping is more preferably 40°C or higher, and even more preferably 43 to 70°C.

[0024] As shown in FIGS. 3A and 3B, in this embodiment, the bead core 11 and the bead filler 12 are crimped together using a crimping device X1. The crimping device X1 includes a core support member X11 having a substantially cylindrical support surface X11a that supports the bead core 11, and a plurality of filler support members X12 that support the bead fillers 12. The plurality of filler support members X12 are arranged in a cylindrical shape. The filler support member X12 is rotatable between a first position Y1 along the axial direction of the core support member X11 and a second position Y2 along a direction perpendicular to the axial direction. In this embodiment, the support surface X11a of the core support member X11 is inclined with respect to the central axis of the core support member X11, but this is not limiting.

[0025] The crimping of the bead core 11 and the bead filler 12 using the crimping device X1 will be described with reference to FIGS. 3A and 3B.

[0026] First, as shown in FIG. 3A, the annular bead core 11 is placed on the support surface X11a of the core support member X11. The bead core 11 is transferred and placed on the support surface X11a by, for example, a robot arm. Then, an extruded rubber member is wound around the outer periphery of the filler support member X12 located at the first position Y1 to form the annular bead filler 12. At this time, the first side surface portion 12b (or the second side surface portion 12c) of the bead filler 12 is supported by the filler support member X12, and the thickness direction of the bead filler 12 is arranged along the radial direction D3 of the bead core 11. The bottom portion 12a of the bead filler 12 is arranged in contact with or close to the bead core 11.

[0027] 3B, the filler support member X12 is rotated to a second position Y2, and the bead filler 12 is turned up, thereby crimping the bead filler 12 onto the bead core 11. In this way, the annular bead member 10 is produced.

[0028] The filler support member X12 may be a bladder, which is a rubber bag-like member. In this case, the bead filler 12 can be turned up by inflating the bladder.

[0029] <Second process> 4, in the second step, the bead filler 12 is supported (attached) to the separator 20, and the bead member 10 is placed so that the radial direction D3 of the bead core 11 is aligned horizontally. At this time, the separator 20 supporting the bead filler 12 is placed (for example, on the placing member X2) so that the separator 20 is on the lower side (the bead filler 12 is on the upper side).

[0030] In this embodiment, the bead member 10 manufactured in the first step is placed on the separator 20 that has been placed previously. This allows the first side surface portion 12b of the bead filler 12 to be attached to the separator 20 by its own weight, eliminating the need to press the bead filler 12 to attach it to the separator 20. The bead member 10 and the separator 20 are transported and placed, for example, by a robot arm. Note that this is not limited to the above, and for example, the bead member 10 may be placed after the first side surface portion 12b of the bead filler 12 is supported (attached) to the separator 20.

[0031] By performing the manufacturing of the bead member 10 in the first step and the attachment of the bead member 10 to the separator 20 in the second step in separate steps, it is possible to prevent the bead filler 12 from being firmly attached to the separator 20, compared to when these steps are performed in the same step. This improves the workability of peeling the bead filler 12 from the separator 20.

[0032] In this embodiment, as shown in FIG. 5, a plurality of bead members 10 supported by separators 20 are stacked in the vertical direction. That is, the separators 20 and the bead members 10 are alternately stacked, but this is not limited to this. The number of stacked bead members 10 is preferably 8 to 10. By using 8 or more bead members 10, it is possible to ensure the cooling time of the bead members 10 in the third step described below. By using 10 or fewer bead members 10, the weight of the stacked bead members 10 and separators 20 causes the lower bead members 10 (bead fillers 12) to firmly adhere to the separator 20, preventing the bead fillers 12 from peeling off from the separator 20.

[0033] The separator 20 is an annular plate-like member having a substantially constant thickness (for example, 5 mm). The outer diameter of the separator 20 is larger than the outer diameter of the bead member 10. The inner diameter of the separator 20 is preferably substantially the same as the inner diameter of the bead member 10 (bead core 11) so that the bead member 10 supported by the separator 20 is suspended from columnar members X22, which will be described later. The separator 20 is preferably formed from resin from the viewpoint of reducing weight and costs.

[0034] The bending strength of the separator 20 is preferably 3 MPa to 20 MPa. By setting the bending strength to 3 MPa or more, the rigidity of the separator 20 can be ensured, and the bead fillers 12 supported by the separator 20 can be prevented from collapsing. By setting the bending strength to 20 MPa or less, the separator 20 can be deformed to peel off the bead fillers 12, improving the workability of peeling off the bead fillers 12 from the separator 20. However, the separator 20 is not limited to the above.

[0035] The mounting member X2 includes a flat plate member X21 and a columnar member X22 extending upward from the mounting member X2 (flat plate member X21). In this embodiment, the flat plate member X21 is polygonal and the columnar member X22 is cylindrical, but this is not limiting. The width and length of the flat plate member X21 are preferably greater than the outer diameter of the separator 20. The height of the columnar member X22 is appropriately set depending on the number and thickness of the bead members 10 stacked, the thickness of the separator 20, etc. The bead member 10 is mounted on the flat plate member X21 by inserting the columnar member X22 into the opening 10a of the bead member 10.

[0036] <3rd process> In the third step, the bead member 10 is cooled. The bead member 10 is preferably cooled to a predetermined temperature, approximately room temperature (room temperature ±2°C). In this embodiment, the bead member 10 is cooled naturally for a cooling time of 15 minutes or more, but this is not limited to this. For example, the bead member 10 may be cooled using a cooling device (e.g., a blower), and the cooling time may be shorter than 15 minutes. When using a cooling device, it is preferable to cool the bottom portion 12a of the bead filler 12, which has a high temperature. In this embodiment, the bead member 10 is cooled while placed on the placing member X2.

[0037] 6, the mounting member X2 is transported by a transport device X3 (e.g., a conveyor) to a mounting position Y3 in the second step, a cooling position Y4 in the third step, and a rotation position Y5 in the fourth step (described later) in that order. After being transported to the rotation position Y5, the mounting member X2 is emptied and then transported back to the mounting position Y3. The transport device X3 stops for a predetermined time at the mounting position Y3 until a predetermined number of bead members 10 have been placed on the mounting member X2.

[0038] In this embodiment, a plurality of (for example, four) mounting members X2 are arranged on the transport device X3. This allows a predetermined number of bead members 10 to be placed on the mounting member X2, and then another bead member 10 to be placed on another mounting member X2 without stopping the production of the bead members 10. This also ensures that the bead members 10 have enough time to cool on the transport device X3 (mounting member X2). The number of mounting members X2 to be arranged is set appropriately depending on the cooling time of the bead members 10, the number of layers, etc.

[0039] <4th process> In the fourth step, as shown in Fig. 7, the bead member 10 supported by the separator 20 is stood up so that the radial direction D3 of the bead core 11 is aligned in the vertical direction. That is, in the fourth step, the bead member 10, which is placed so that the radial direction D3 of the bead core 11 is aligned in the horizontal direction, is rotated 80 to 100 degrees. In Fig. 7, the bead member 10 before rotation is indicated by a two-dot chain line, and the bead member 10 after rotation is indicated by a solid line.

[0040] In this embodiment, the bead member 10 is placed on the mounting member X2 and is rotated by a rotation means X4 (e.g., a motor), but is not limited to this. The rotation means X4 is disposed on the mounting member X2 or the conveying device X3 (see FIG. 6) and rotates the mounting member X2 at a rotation position Y5.

[0041] The bead members 10 erected in the fourth step are transferred to and hung from a hanging member (not shown) for accommodating the bead members 10 while supported by the separators 20. The bead members 10 are transferred using a robot arm or other transfer means. The hanging member is, for example, a rod-shaped member extending horizontally and attached to a transport vehicle. By accommodating the bead members 10 in a hanging (standing) manner, more bead members 10 can be accommodated than when the bead members 10 are stored by being placed on the floor, thereby improving the efficiency of accommodating the bead members 10. Furthermore, by accommodating the bead members 10 while supported by the separators 20, it is possible to prevent adjacent bead members 10 from coming into contact with each other and adhering to each other.

[0042] The placed bead component 10 may be erected by directly hanging it from a hanging member using a transfer means such as a robot arm. This allows the bead component 10 to be erected without rotating the placement component X2 using the rotation means X4.

[0043] As described above, in this embodiment, the manufacturing method of the pneumatic tire T includes a first step of press-fitting the bead filler 12, which becomes thinner toward the outside in the radial direction D3 of the bead core 11, onto the outer peripheral portion 11a of the bead core 11 to produce an annular bead member 10; a second step of supporting the bead filler 12 on the separator 20 and placing the bead member 10 so that the radial direction D3 of the bead core 11 is aligned horizontally; and a third step of cooling the bead member 10.

[0044] According to this method, by placing the manufactured bead member 10 while it is supported by the separator 20 and cooling it, even if the bead filler 12 peels off from the separator 20 due to deformation caused by thermal contraction, the bead filler 12 can be supported by the separator 20 again by its own weight. This makes it possible to prevent the bead filler 12 from collapsing when the bead member 10 is cooling. Furthermore, the roundness of the bead member 10 can be ensured compared to when the bead member 10 is erected immediately after manufacture.

[0045] Furthermore, in the manufacturing method of the pneumatic tire T as in this embodiment, the first step is preferably a method in which one side portion (first side portion 12b) of the bead filler 12, which is arranged so that the thickness direction of the bead filler 12 is along the radial direction D3 of the bead core 11, is supported by a support member (filler support member X12), and the bead filler 12 is turned up by the support member (filler support member X12) to be pressed against the bead core 11.

[0046] According to this method, by supporting one side surface (first side surface 12b) of the bead filler 12 on a support member (filler support member X12), it is possible to suppress deformation of the bead filler 12 toward the one side surface (first side surface 12b) that occurs when turning up the bead filler 12. In addition, deformation (curl) of the bead filler 12 that occurs when turning up the bead filler 12 in the first step can be corrected by the weight of the bead filler 12.

[0047] In addition, in the manufacturing method of the pneumatic tire T as in this embodiment, the second step is preferably a method in which a plurality of bead members 10 supported by the separators 20 are stacked and placed in the vertical direction.

[0048] According to this method, a portion of the bead filler 12 (for example, the bottom portion 12a) is pressed against the separator 20 by the weight of the bead member 10 and separator 20 stacked thereon. This strengthens the adhesion of the bead filler 12 to the separator 20, and prevents the bead filler 12 from being deformed due to thermal contraction. Furthermore, by pressing the bottom portion 12a of the bead filler 12 with the bead member 10 and separator 20 stacked thereon, deformation (curl) of the bead filler 12 that occurs during turn-up can be prevented.

[0049] Furthermore, as in this embodiment, the method for manufacturing the pneumatic tire T preferably includes a fourth step of erecting the bead member 10 supported by the separator 20 so that the radial direction D3 of the bead core 11 is aligned with the up-down direction.

[0050] According to this method, the efficiency of accommodating the bead members 10 can be improved compared to the state in which the bead members 10 are simply placed.

[0051] Furthermore, in the manufacturing method of the pneumatic tire T as in this embodiment, it is preferable that in the second step, the bead member 10 is placed by inserting the opening 10a of the bead member 10 into a columnar member X22 extending upward from the mounting member X2 on which the bead member 10 is placed, in the third step, the bead member 10 is cooled while placed on the mounting member X2, and in the fourth step, the bead member 10 is erected by rotating the mounting member X2.

[0052] According to this method, the bead component 10 can be hung from the columnar component X22 by rotating the mounting component X2 on which the bead component 10 is mounted. This improves the workability of erecting the bead component 10.

[0053] The manufacturing method of the pneumatic tire T is not limited to the configurations and methods of the above-described embodiment, and is not limited to the above-described effects. Of course, the manufacturing method of the pneumatic tire T can be modified in various ways without departing from the spirit of the present invention.

[0054] The transfer, conveyance, and rotation of the bead members 10 and separators 20 in the first to fourth steps are not limited to those described above, and may be performed manually. [Explanation of symbols]

[0055] T...pneumatic tire, 1...bead portion, 10...bead member, 10a...opening, 11...bead core, 11a...outer periphery, 12...bead filler, 12a...bottom, 12b...first side portion, 12c...second side portion, 12d...tip portion, 20...separator, 2...sidewall, 3...tread, 4...carcass ply, 5...inner liner, 6...belt layer, 7...tread rubber, 8...chafer pad, X1...pressing device, X11...core support member, X11a...support surface, X12...filler support member, X2...mounting member, X21...flat member, X22...columnar member, X3...conveyor device, X4...rotating means

Claims

1. a first step of fabricating an annular bead member by press-fitting a bead filler, the thickness of which decreases toward the radially outer side of an annular bead core, onto an outer periphery of the annular bead core; a second step of supporting the bead filler on a separator and stacking a plurality of the bead members in the vertical direction so that the radial direction of the bead core is aligned horizontally; a third step of cooling the bead member; a fourth step of standing the bead member supported by the separator so that the radial direction of the bead core is aligned with the up-down direction, The second step includes inserting a columnar member extending upward from a mounting member on which the bead members are mounted into the openings of the plurality of bead members, the third step includes cooling the bead member while the bead member is placed on the mounting member; In the fourth step, the plurality of bead members are erected by rotating the mounting member.

2. 2. The method for manufacturing a pneumatic tire according to claim 1, wherein the first step includes supporting one side portion of the bead filler, the bead filler being arranged so that a thickness direction of the bead filler is aligned with a radial direction of the bead core, on a support member, and turning up the bead filler using the support member to press it against the bead core.

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