JP7534905B2 - Manufacturing method of pneumatic tire - Google Patents

Description

This disclosure relates to a method for manufacturing a pneumatic tire.

A green tire is made by stacking multiple tire-constituting rubber components such as the inner liner, carcass, beads, sidewall rubber, belt, and tread using a molding device, and then the green tire is heated and pressurized in a mold to vulcanize and mold it into a pneumatic tire.

Sidewall rubber with a cross-sectional shape that has both thick and thin sections cannot be formed in one step by extrusion molding, so it is manufactured using the so-called ribbon method. The ribbon method is a method of forming rubber components with any cross-sectional shape by winding a strip-shaped ribbon multiple times in a spiral shape around the tire axis (see Patent Document 1).

However, the ribbon method requires wrapping the ribbon rubber multiple times, which takes time and increases the cycle time.

In addition, if air pockets form between the rubber components that make up the raw tire, production defects will occur, so there is a need to prevent air pockets from forming.

JP 2013-22788 A

This disclosure provides a method for manufacturing pneumatic tires that reduces cycle time and suppresses the occurrence of manufacturing defects due to air pockets.

The manufacturing method of the pneumatic tire disclosed herein includes a step of overlapping a first sidewall rubber with a second sidewall rubber having a width in the axial direction of the molding drum that is shorter than that of the first sidewall rubber, and a step of wrapping the overlapped first sidewall rubber and the second sidewall rubber around a tire-constituting rubber member on the molding drum for one circumference of the tire.

1 is a meridian cross-sectional view showing a pneumatic tire manufactured by the manufacturing method of the present disclosure. FIG. 4 is an explanatory diagram relating to molding of a first assembled member. FIG. 4 is an explanatory diagram relating to molding of a first assembled member. FIG. 2 is a diagram showing a schematic diagram of a manufacturing apparatus for implementing the present manufacturing method. 4A and 4B are a plan view and a cross-sectional view perpendicular to the conveying direction of a junction portion, respectively. 4A and 4B are a plan view and a cross-sectional view perpendicular to the conveying direction, respectively, of a portion upstream of the junction in the conveying path of the second conveying device; FIG. 11 is a diagram illustrating a case where the angle between the cut surfaces of the first and second sidewall rubbers and the thickness direction is large (for example, 60 degrees), and an explanatory diagram regarding the overlap. FIG. 13 is a diagram showing a case where the angle of the cut surfaces of the first and second sidewall rubbers with respect to the thickness direction is 0 degrees. FIG. 13 is a diagram showing a case where the angle of the cut surfaces of the first and second sidewall rubbers with respect to the thickness direction is small (for example, 15 degrees). FIG. 4 is a diagram showing the thickness of a first sidewall rubber and the thickness of a second sidewall rubber disposed on the outer periphery of the first sidewall rubber. FIG. 11 is an explanatory diagram relating to molding of a second assembled member. 6 is an explanatory diagram relating to a joining process of a first assembled member and a second assembled member. FIG. FIG. 11 is an explanatory diagram showing a process of pressing the second sidewall rubber by a washer roller. FIG. 11 is an explanatory diagram showing a step of forming a through hole in the second sidewall rubber by a needle. 4A and 4B are a plan view and a cross-sectional view showing a first sidewall rubber having a plurality of grooves formed therein by a groove forming portion.

This embodiment of the present disclosure will be described below with reference to the drawings.

[Pneumatic tire structure]
FIG. 1 is a meridian cross-sectional view of a pneumatic tire vulcanized by pressurizing and heating a raw tire in a mold. In FIG. 1, only the first sidewall rubber 90 and the second sidewall rubber 91 are hatched. In FIG. 1, only half of the tire from the tire equatorial plane CL is illustrated in the meridian cross-section. As shown in FIG. 1 with some parts omitted, the pneumatic tire includes a pair of beads 1, sidewalls 2 extending from each bead 1 to the tire radially outer side RD1, and a tread 3 connecting the tire radially outer side RD1 ends of the sidewalls 2. In the bead 1, an annular bead core 1a formed by laminating rubber-coated bead wires (e.g., metal wires) and a bead filler 1b made of hard rubber are arranged. The bead 1 is attached to a bead seat (not shown) of a rim, filled with internal pressure, and appropriately fitted to the rim flange by the tire internal pressure, and the tire is fitted to the rim.

The tire also has a toroidal carcass 4 that is arranged so as to span between a pair of beads 1 and extends from the tread 3 through the sidewall 2 to the bead 1. The carcass 4 is made up of at least one carcass ply, and its end is secured in a wound-up state via the bead core 1a. An inner liner rubber 5 for maintaining air pressure is arranged on the inner periphery of the carcass 4.

A belt 6 is arranged on the outer circumference of the carcass 4 in the tread 3, reinforcing the carcass 4 by a hoop effect. The belt 6 has two belt plies with cords that extend at a predetermined angle to the tire circumferential direction, and each ply is layered so that the cords cross each other in opposite directions. A belt reinforcing layer 7 is arranged on the outer circumference side of the belt 6, and tread rubber 8 with a tread pattern formed thereon is arranged on the outer circumference surface.

A sidewall rubber 9 that forms the tire side surface is arranged on the outer periphery of the carcass 4 in the sidewall 2. The buttress, which is an area of the tire side surface that is radially outward RD1 of the tire's maximum width portion Wh, has an uneven portion 10 having recesses and protrusions along the tire circumferential direction as a design. Therefore, as shown in FIG. 1, the buttress in the sidewall rubber 9 requires a larger rubber volume than the area of the sidewall rubber 9 that is radially inward of the buttress. FIG. 1 shows a tire after vulcanization molding, and the sidewall rubber 9 includes a first sidewall rubber 90 and a second sidewall rubber 91. The first sidewall rubber 90 is a sheet-like rubber member that extends from the bead 1 to the tread 3 and is wrapped around the tire. The second sidewall rubber 91 is a sheet-like rubber member that is shorter in width than the first sidewall rubber 90 and is wrapped around the outer periphery of the first sidewall rubber 90 for one circumference of the tire.

[Manufacturing method of pneumatic tire]
The method for manufacturing a pneumatic tire includes a step of manufacturing a raw tire T3 by stacking a plurality of tire-constituting rubber members, and a step of vulcanizing and molding the raw tire T3 in a mold by heating and pressurizing the raw tire T3. The step of manufacturing the raw tire T3 includes a step of molding a first assembled member T1 also called a first case, a step of molding a second assembled member T2 also called a second case, and a step of inflating the first assembled member T1 and combining it with the second assembled member T2 to obtain the raw tire T3.

[Molding of First Assembly Member T1 (First Case)]
The process of molding the first assembled member T1 (first case) will be described with reference to Figs. 2 and 3. In Fig. 2, only the carcass 4 is hatched. In Fig. 3, only the carcass 4 is hatched. The inner liner rubber 5, the chafer (not shown), and the carcass 4 are wound around the molding drum 50 shown in Fig. 2. Then, the bead filler 1b and the bead core 1a are arranged on both ends of the drum axial direction of the molding drum 50 of the carcass 4, and the carcass 4 is wound up around the bead core 1a and the bead filler 1b by inflating the bladder (not shown). In this way, the tire constituent rubber members are arranged on the molding drum 50. Next, there is a process of winding the sidewall rubber 9 around the tire constituent rubber members.

Incidentally, there is a tire in which a design is provided by unevenness on the buttress of the sidewall. Such a tire is required to have a larger volume of rubber in the buttress than other parts of the sidewall. When viewed only from the sidewall rubber, the cross-sectional shape has both thick and thin parts. In order to shorten the cycle time compared to the ribbon method as in Patent Document 1, it is considered to wind the first sidewall rubber around the tire constituent rubber member including the carcass arranged on the forming drum, and then wind the second sidewall rubber around the first sidewall rubber for one circumference of the tire. However, there is a risk that the uneven shape of the tire constituent rubber member will appear on the outer peripheral surface of the first sidewall rubber after winding. And, since the second sidewall rubber is wound around the outer peripheral surface where the uneven shape of the first sidewall rubber appears, air pockets are generated between the first sidewall rubber and the second sidewall rubber, which is considered to cause manufacturing defects.
Therefore, the first assembled member T1 is formed as follows.

First, as shown in FIG. 2, the first sidewall rubber 90 and the second sidewall rubber 91 are overlapped. The second sidewall rubber 91 has a smaller width in the drum axial direction AD than the first sidewall rubber 90. The second sidewall rubber 91 is disposed radially outward of the first sidewall rubber 90.

Next, the overlapping first sidewall rubber 90 and second sidewall rubber 91 are cut into one circumference of the tire using a cutter.

2 and 3, the first sidewall rubber 90 and the second sidewall rubber 91 in the overlapped state are wound around the tire constituent rubber members (the inner liner rubber 5, the carcass 4, etc.) on the molding drum 50 for one circumference of the tire to obtain the first assembled member T1 (first case). These sidewall rubbers 9 (90, 91) form a pair. The first sidewall rubber 90 and the second sidewall rubber 91 have a length equivalent to one circumference of the tire. The second sidewall rubber 91 has a shorter width along the drum axial direction AD than the first sidewall rubber 90. Therefore, the second sidewall rubber 91 has a shorter width in the drum axial direction AD than the first sidewall rubber 90. In this embodiment, the first sidewall rubber 90 and the second sidewall rubber 91 have the same rubber composition, but this is not limited to this.

Figure 4 is a schematic diagram showing a manufacturing device that molds the first assembled member T1 (first case). As shown in Figure 4, the manufacturing device has a molding drum 50 on which the tire constituent rubber members are arranged, a first conveying device 52 that conveys the first sidewall rubber 90 from a first carriage 51 that holds the first sidewall rubber 90 in a payable manner toward the molding drum 50 while unwinding it, and a second conveying device 54 that conveys the second sidewall rubber 91 from a second carriage 53 that holds the second sidewall rubber 91 in a payable manner toward the molding drum 50 while unwinding it.

The first carriage 51 rotatably supports a roller around which the first sidewall rubber 90 is wound via a separation sheet (not shown), and the first sidewall rubber 90 is pulled by the first conveying device 52 to pay out the first sidewall rubber 90. The first sidewall rubber 90 paid out from the first carriage 51 is placed on a conveyor such as a roller and is conveyed toward the forming drum 50.

The second carriage 53 rotatably supports a roller around which the second sidewall rubber 91 is wound via a separation sheet (not shown), and the second sidewall rubber 91 is pulled by the second conveying device 54 to pay out the second sidewall rubber 91. The second sidewall rubber 91 paid out from the second carriage 53 is placed on a conveyor such as a roller and is conveyed toward the forming drum 50.

At the downstream of the first conveying device 52 and the second conveying device 54, a junction 55 is provided where the conveying path of the first conveying device 52 and the conveying path of the second conveying device 54 join together. The junction 55 overlaps the second sidewall rubber 91 on the outer side (upper) of the drum radial direction of the first sidewall rubber 90. In this embodiment, in order to overlap the first sidewall rubber 90 and the second sidewall rubber 91 for one circumference of the tire at the junction 55, it is preferable that the dimension L1 in the conveying direction of the junction 55 is equal to or greater than the length of one circumference of the tire of the first sidewall rubber 90 and the second sidewall rubber 91. The first sidewall rubber 90 and the second sidewall rubber 91 in the overlapped state are cut to the length of one circumference of the tire by the cutter 56. As shown in FIG. 4, the junction 55 is provided with a pressing roller 59 that presses the second sidewall rubber 91 overlapped on the first sidewall rubber 90. The pressure roller 59 has a larger dimension in the drum axial direction AD than the second sidewall rubber 91, but a smaller dimension in the drum axial direction AD than the first sidewall rubber 90. This is because it is necessary to press the second sidewall rubber 91 to remove the air between the second sidewall rubber 91 and the first sidewall rubber 90.

5 is a plan view of the junction 55 and a cross-sectional view perpendicular to the conveying direction TD. In the plan view of FIG. 5, only the surfaces of the first sidewall rubber 90 and the second sidewall rubber 91 are hatched. In the cross-sectional view of FIG. 5, only the first sidewall rubber 90 and the second sidewall rubber 91 are hatched. As shown in FIG. 5, the first sidewall rubber 90 is placed on a conveyor such as a roller of the first conveying device 52 and conveyed toward the forming drum 50. The first guides 57 are arranged in pairs on both sides of the first sidewall rubber 90 in the drum axial direction and are parallel to the conveying direction TD. The first guide 57 has a guide surface 57a parallel to the conveying direction TD of the first sidewall rubber 90, and the guide surface 57a is brought into contact with the first sidewall rubber 90 to guide the first sidewall rubber 90. The guide surface 57a maintains the first sidewall rubber 90 in a position parallel to the conveying direction TD. This makes it possible to prevent the first sidewall rubber 90 from being skewed (inclined) with respect to the transport direction TD.

6 is a plan view of the portion upstream of the junction 55 in the conveying path of the second conveying device 54 (the portion immediately before merging with the junction 55) and a cross-sectional view perpendicular to the conveying direction TD. In the plan view of FIG. 6, only the surface of the second sidewall rubber 91 is hatched. In the cross-sectional view of FIG. 6, only the second sidewall rubber 91 is hatched. As shown in FIG. 6, the second sidewall rubber 91 is placed on a conveyor such as a roller of the second conveying device 54 and conveyed toward the forming drum 50. The second sidewall rubber 91 merges onto the first sidewall rubber 90 (radially outside the forming drum 50). The second guides 58 are arranged in pairs on both sides of the second sidewall rubber 91 in the drum axial direction and are parallel to the conveying direction TD. The second guide 58 has a guide surface 58a parallel to the transport direction TD of the second sidewall rubber 91, and guides the second sidewall rubber 91 by bringing the guide surface 58a into contact with the second sidewall rubber 91. The guide surface 58a keeps the second sidewall rubber 91 parallel to the transport direction TD. This makes it possible to prevent the second sidewall rubber 91 from being skewed (inclined) with respect to the transport direction TD.

As shown in FIG. 7A, the first sidewall rubber 90 and the second sidewall rubber 91 are cut into a length equivalent to one circumference of the tire by a cutter 56 (see FIG. 4) while overlapping each other. Then, the cut surfaces 9a at both ends of the drum circumferential direction of the first sidewall rubber 90 and the second sidewall rubber 91 are wound around the tire constituent rubber member on the molding drum 50, and are joined together. However, if the thickness of the sidewall rubber 9 such as the first sidewall rubber 90 and the second sidewall rubber 91 is thin, the adhesion between the cut surfaces 9a of the sidewall rubber 9 is weak, and proper joining cannot be performed. In that case, as shown in FIG. 7A, the angle θ of the cut surface 9a of the sidewall rubber 9 with respect to the thickness direction DD is increased (for example, 60 degrees), and the cut surface 9a is enlarged, thereby ensuring the adhesive force. However, as shown in FIG. 7A, when the ends (cut surfaces 9a) of the sidewall rubber 9 in the tire circumferential direction are misaligned, if the angle θ of the cut surfaces 9a with respect to the thickness direction DD is large, the cut surfaces 9a do not push back against each other, and one cut surface 9a exceeds the other cut surface 9a, causing an overlap Lp1, which may result in deterioration of uniformity. Note that the thickness direction DD is a direction perpendicular to the bottom surface (the inner surface in the tire radial direction) of the sidewall rubber 9.

Figure 8 shows the thickness of the first sidewall rubber 90 and the thickness of the second sidewall rubber 91 arranged on the outer periphery of the first sidewall rubber 90. Measurement points are indicated by circles, and the measurement points are connected by straight lines.

In this embodiment, as shown in FIG. 8, there is a portion Ar0 where the combined thickness of the first sidewall rubber 90 and the second sidewall rubber 91 is 10 mm or more. As a result, even if the angle θ of the cut surfaces 9a of the first sidewall rubber 90 and the second sidewall rubber 91 with respect to the thickness direction DD is set to 0 degrees, for example, as shown in FIG. 7B, the size of the cut surface 9a necessary to ensure the adhesive force between the cut surfaces after joining can be secured, and proper joining can be achieved. Furthermore, in this embodiment, as shown in FIG. 7B and FIG. 7C, the angle θ of the cut surfaces 9a of the first sidewall rubber 90 and the second sidewall rubber 91 with respect to the thickness direction DD is set to 0 degrees or more and 30 degrees or less. In particular, the angle θ is preferably 0 degrees or more and 15 degrees or less. As a result, when the ends (cut surfaces 9a) of the sidewall rubber 9 in the drum circumferential direction are misaligned, the cut surfaces 9a push back against each other, making it difficult for one cut surface 9a to exceed the other cut surface 9a, and the occurrence of overlap Lp1 can be suppressed, and deterioration of uniformity can be suppressed. More preferably, the angle θ is 0 degrees. If the angle θ is 0 degrees, one cut surface 9a does not exceed the other cut surface 9a, so the occurrence of overlap can be suppressed and deterioration of uniformity can be prevented.

As shown in FIG. 8, the first sidewall rubber 90 has a first region Ar1 where the second sidewall rubber 91 overlaps, and a second region Ar2 where the second sidewall rubber 91 does not overlap. The second region Ar2 has a third region Ar3 that is thicker than the maximum thickness Dmax of the first region Ar1. This ensures adhesive strength between the cut surfaces 9a at at least two locations, the first region Ar1 and the third region Ar3, and makes it possible to set the angle θ of the cut surface 9a with respect to the thickness direction DD to 30 degrees or less.

The second region Ar2 has a fourth region Ar4 between the first region Ar1 and the third region Ar3, which is thinner than the maximum thickness Dmax of the first region Ar1. This makes it possible to ensure the adhesive strength between the cut surfaces 9a and prevent deterioration of uniformity without making the entire sidewall rubber 9 thick, and also makes it possible to obtain a shape suitable for the sidewall rubber.

In the embodiment shown in FIG. 3 and FIG. 8, the second sidewall rubber 91 is thicker than the first sidewall rubber 90 in order to increase the rubber volume in the area where the design is desired while reducing the overall volume of the tire to reduce its weight, but this is not limited to the above. For example, the first sidewall rubber 90 may be thicker than the second sidewall rubber 91, or the first sidewall rubber 90 and the second sidewall rubber 91 may be the same thickness.

[Molding of second assembled member T2 (second case)]
The process of forming the second assembled member T2 (second case) will be described with reference to Fig. 9. In Fig. 9, the surface of the belt 6 is hatched. As shown in Fig. 9, the belt 6 and the belt reinforcing layer 7 (not shown in Fig. 9) are wound around the belt drum 151, and then the tread rubber 8 is wound around the tire for one circumference to obtain the second assembled member T2 (second case).

[Connection of the first assembled member T1 and the second assembled member T2]
10, in the forming device 152, the second assembled member T2 is placed on the outer periphery of the first assembled member T1, the bead portions of the first assembled member T1 are brought close to each other while the first assembled member T1 is inflated by a bladder, and the second assembled member T2 is pressed against the first assembled member T1 by a stitcher to join the second assembled member T2 and the first assembled member T1 to form a green tire T3. According to this method, as shown in FIG. 10 and FIG. 1, the tread rubber 8 is placed on the outer side in the tire radial direction of the first sidewall rubber 90 and the second sidewall rubber 91.

<Modification>
(1) In the present embodiment, the first sidewall rubber 90 and the second sidewall rubber 91 are overlapped to a length equivalent to one circumference of the tire and then cut. The circumferential leading ends of the overlapped first sidewall rubber 90 and second sidewall rubber 91 are attached to a tire-constituting rubber member on the molding drum 50, and the molding drum 50 is rotated to wrap the first sidewall rubber 90 and the second sidewall rubber 91 around the tire. However, this is not limited to the above.
For example, after overlapping the leading ends of the first sidewall rubber 90 and the second sidewall rubber 91 in the drum circumferential direction, the leading ends of the overlapped first sidewall rubber 90 and the second sidewall rubber 91 are attached to a tire constituent rubber member, and the molding drum is rotated to wind the first sidewall rubber 90 and the second sidewall rubber 91. While winding the first sidewall rubber 90 and the second sidewall rubber 91, the first sidewall rubber 90 and the second sidewall rubber 91 may be cut by the cutter 56 when the first sidewall rubber 90 and the second sidewall rubber 91 are overlapped for one circumference of the tire. At this time, in a state where the leading ends of the first sidewall rubber 90 and the second sidewall rubber 91 in the drum circumferential direction are wound around the tire constituent rubber member on the molding drum 50, the end portions of the first sidewall rubber 90 and the second sidewall rubber 91 in the drum circumferential direction are cut. That is, the overlapped first sidewall rubber 90 and second sidewall rubber 91 are wound around the tire constituent rubber member on the building drum 50, and the second sidewall rubber 91 is overlapped on the first sidewall rubber 90 upstream of the overlapping, simultaneously occurring. In this way, the dimension of the junction 55 does not require the length of the sidewall rubber 9 around the tire, and the junction 55 can be made shorter than the length of the sidewall rubber 9 around the tire, making it possible to avoid an increase in the size of the device.

(2) In both the above embodiment and the above method (1), the overlapping process of the first sidewall rubber 90 and the second sidewall rubber 91 and the process of winding the overlapped first sidewall rubber 90 and the second sidewall rubber 91 around the tire constituent rubber member on the molding drum 50 are performed on the same line. This may be performed on a separate line. However, the same line is preferable to a separate line. If it is performed on a separate line, it becomes necessary to wind the overlapped first sidewall rubber 90 and the second sidewall rubber 91 around a dolly, which causes the shape (profile) of each sidewall rubber to collapse. That is, as in the present embodiment or the above method (1), after overlapping the first sidewall rubber 90 and the second sidewall rubber 91, it is preferable to start the process of winding the overlapped first sidewall rubber 90 and the second sidewall rubber 91 around the tire constituent rubber member on the molding drum 50 without winding the overlapped first sidewall rubber 90 and the second sidewall rubber 91 around a holding tool such as a dolly.

(3) As shown in FIG. 13, before the first sidewall rubber 90 and the second sidewall rubber 91 are overlapped, a groove forming unit 300 may form a plurality of grooves 90b extending in the drum axis direction AD on the planned surface 90a on which the second sidewall rubber 91 of the first sidewall rubber 90 overlaps. The plurality of grooves 90b are continuously formed from one end to the other in the drum axis direction AD of the planned surface 90a. The groove forming unit 300 may be, for example, a jig used for knurling. If such a plurality of grooves 90b are formed, it is possible to use these grooves 90b for air venting. In the example of FIG. 13, the grooves 90b extend parallel to the drum axis direction AD, but they do not have to be parallel to the drum axis direction AD as long as they intersect with the drum axis direction AD. Of course, a plurality of grooves extending in the drum axis direction AD may be formed on the surface of the first sidewall rubber 90 that is the inner surface in the drum radial direction.

(4) As in the above embodiment, the process includes pressing the first sidewall rubber 90 and the second sidewall rubber 91, which are stacked on top of each other, with the pressing roller 59. However, the pressing roller 59 may be changed to a washer roller 159 shown in FIG. 11. As shown in FIG. 11, the washer roller 159 has a support shaft 159a and a plurality of washers 159b arranged along the support shaft 159a. Each of the plurality of washers 159b is supported by the support shaft 159a so as to be displaceable in the axial radial direction of the support shaft 159a independently of the other washers 159b. As a configuration for supporting the washer 159b so as to be displaceable in the axial radial direction, the annular portion of the washer 159b and the support shaft 159a may be connected with a cylindrical elastic member such as rubber, or the annular portion of the washer 159b and the support shaft 159a may be connected with a spring body such as a coil spring that rotates spirally around the support shaft 159a. The outer diameter of each washer 159b is 5 to 10 mm. The washer 159b is made of metal.

(5) As shown in FIG. 12, a needle 200 may be inserted from the second sidewall rubber 91 toward the first sidewall rubber 90 in the second sidewall rubber 91 that is superimposed on the first sidewall rubber 90, to form a through hole 9c in the second sidewall rubber 91 that reaches the first sidewall rubber 90. This through hole 9c is effective for venting air, particularly during vulcanization. The length of the needle 200 may be, for example, 10 mm or more.

As described above, the manufacturing method of a pneumatic tire of this embodiment includes a step of overlapping the first sidewall rubber 90 and the second sidewall rubber 91, which has a shorter width in the drum axial direction AD than the first sidewall rubber 90, and a step of wrapping the overlapped first sidewall rubber 90 and second sidewall rubber 91 around one circumference of the tire around a tire constituent rubber member on the molding drum 50.
The pneumatic tire manufacturing apparatus of this embodiment includes a molding drum 50 on which tire constituent rubber components are arranged, a first conveying device 52 that conveys a first sidewall rubber 90, and a second conveying device 54 that conveys a second sidewall rubber 91 that is shorter in width in the drum axial direction AD of the molding drum 50 than the first sidewall rubber 90. The first sidewall rubber 90 and the second sidewall rubber 91 are overlapped at a junction 55 between the conveying path of the first conveying device 52 and the conveying path of the second conveying device 54, and the overlapped first sidewall rubber 90 and second sidewall rubber 91 are wrapped around the tire constituent rubber components on the molding drum 50 for one revolution of the tire.

In this way, the first sidewall rubber 90 and the second sidewall rubber 91 in an overlapping state are wound around the tire constituent rubber member on the molding drum 50, so that air pockets can be prevented from forming between the first sidewall rubber 90 and the second sidewall rubber 91, and the occurrence of manufacturing defects due to air pockets can be prevented. In addition, because the first sidewall rubber 90 and the second sidewall rubber 91 are wound around the tire once, the cycle time can be reduced compared to the ribbon method in which ribbon rubber is wound around the tire multiple times.

Although not particularly limited, as in the manufacturing method of this embodiment, the method may include a step of cutting the first sidewall rubber 90 and the second sidewall rubber 91 in an overlapping state to a length equivalent to one circumference of the tire, have a portion where the combined thickness of the first sidewall rubber 90 and the second sidewall rubber 91 is 10 mm or more, and the angle θ of the cut surface 9a of the first sidewall rubber 90 and the second sidewall rubber 91 with respect to the thickness direction DD is 0 degrees or more and 30 degrees or less.
Although not particularly limited, like the manufacturing apparatus of this embodiment, the apparatus may be equipped with a cutter 56 that cuts the first sidewall rubber 90 and the second sidewall rubber 91 to the length of one circumference of the tire while they are overlapped, have a portion where the combined thickness of the first sidewall rubber 90 and the second sidewall rubber 91 is 10 mm or more, and have an angle θ of the cut surface 9a of the first sidewall rubber 90 and the second sidewall rubber 91 with respect to the thickness direction DD that is greater than or equal to 0 degrees and less than 30 degrees.

If the combined thickness of the first sidewall rubber 90 and the second sidewall rubber 91 is 10 mm or more, the adhesive strength between the cut surfaces 9a after joining can be ensured, and they can be joined properly. However, if the angle θ of the cut surface 9a with respect to the thickness direction DD is 0 degrees or more and 30 degrees or less, the occurrence of overlap Lp1 can be reduced even if the end of the sidewall rubber 9 is misaligned, and deterioration of uniformity can be suppressed.

Although not particularly limited, as in the manufacturing method or manufacturing apparatus of this embodiment, the first sidewall rubber 90 may have a first portion Ar1 where the second sidewall rubber 91 overlaps and a second portion Ar2 where the second sidewall rubber 91 does not overlap, and the second portion Ar2 may have a third portion Ar3 that is thicker than the maximum thickness Dmax of the first portion Ar1.

If the sidewall rubber 9 is thin, the adhesive strength between the cut surfaces 9a after joining will be weak. The first region Ar1 has the first sidewall rubber 90 and the second sidewall rubber 91 overlapped to ensure the thickness required for adhesion, and the third region Ar3 is thicker than the maximum thickness Dmax of the first region Ar1, so that the thickness required for adhesion can be ensured equivalent to that of the first region Ar1. Therefore, the adhesive strength between the cut surfaces 9a can be ensured at at least two locations, the first region Ar1 and the third region Ar3, so the angle θ of the cut surface 9a with respect to the thickness direction DD can be set to a small value of 30 degrees or less. This makes it possible to ensure the adhesive strength between the cut surfaces 9a and suppress deterioration of uniformity at the same time.

Although not particularly limited, as in the manufacturing method or manufacturing apparatus of this embodiment, the second portion Ar2 may have a fourth portion Ar4 between the first portion Ar1 and the third portion Ar3, the fourth portion Ar4 being thinner than the maximum thickness Dmax of the first portion Ar1.

According to this configuration, in the first region Ar1, both the first sidewall rubber 90 and the second sidewall rubber 91 can ensure sufficient rubber volume and ensure the adhesive strength between the cut surfaces 9a. In addition, the third region Ar3 has a thickness that ensures the adhesive strength between the cut surfaces 9a, and the fourth region Ar4, where the sidewall rubber 9 is thin, is between the first region Ar1 and the third region Ar3. This makes it possible to ensure the adhesive strength between the cut surfaces 9a and suppress deterioration of uniformity without making the entire sidewall rubber 9 thick, and to obtain a shape suitable for the sidewall rubber 9. For example, it is possible to make the first region Ar1 a buttress, the third region Ar3 near the bead 1, and the fourth region Ar4 a narrow portion of the tire between the buttress and the bead 1.

Although not particularly limited, as in the manufacturing method of this embodiment, the method may include a process of guiding an end of the first sidewall rubber 90 in the drum axis direction AD transported toward the molding drum 50 with a first guide 57, and a process of guiding an end of the second sidewall rubber 91 in the drum axis direction AD transported toward the molding drum 50 with a second guide 58, in which the first guides 57 are arranged in pairs on both sides of the first sidewall rubber 90 in the drum axis direction and are parallel to the transport direction TD of the first sidewall rubber 90, and the second guides 58 are arranged in pairs on both sides of the second sidewall rubber 91 in the drum axis direction and are parallel to the transport direction of the second sidewall rubber 91.
Although not particularly limited, as in the manufacturing apparatus of this embodiment, a first guide 57 that guides the end in the drum axis direction AD of the first sidewall rubber 90 transported toward the molding drum 50, and a second guide 58 that guides the end in the drum axis direction AD of the second sidewall rubber 91 transported toward the molding drum 50, the first guides 57 being arranged in a pair on both sides in the drum axis direction of the first sidewall rubber 90 and parallel to the transport direction TD of the first sidewall rubber 90, and the second guides 58 being arranged in a pair on both sides in the drum axis direction of the second sidewall rubber 91 and parallel to the transport direction of the second sidewall rubber 91.

In this way, the first sidewall rubber 90 and the second sidewall rubber 91 are guided by the first guide 57 and the second guide 58, respectively, so that the first sidewall rubber 90 and the second sidewall rubber 91 are suppressed or prevented from skewing, and the two can be properly overlapped.

Although not particularly limited, as in the manufacturing method of modified example (3) of this embodiment, in a process before overlapping the first sidewall rubber 90 and the second sidewall rubber 91, a process of forming a plurality of grooves 90b extending in the drum axial direction AD in the contact area 90a of the first sidewall rubber 90 with the second sidewall rubber 91 may be included.
Although not particularly limited, as in the manufacturing apparatus of modified example (3) of this embodiment, in a process before overlapping the first sidewall rubber 90 and the second sidewall rubber 91, a groove forming unit 300 may be provided that forms a plurality of grooves 90b extending in the drum axial direction AD in a contact area 90a of the first sidewall rubber 90 with the second sidewall rubber 91.

In this way, even if air accumulates between the first sidewall rubber 90 and the second sidewall rubber 91, the air can be released through the groove 90b, making it possible to prevent air accumulation.

Although not particularly limited, the manufacturing method of this embodiment may include a process of pressing the first sidewall rubber 90 and the second sidewall rubber 91 stacked on top of each other with a washer roller 159, and the washer roller 159 has a support shaft 159a and a plurality of washers 159b arranged along the support shaft 159a, and each of the plurality of washers 159b is supported on the support shaft 159a so as to be displaceable in the axial radial direction of the support shaft 159a independently of the other washers 159b.
Although not particularly limited, as in the manufacturing apparatus of this embodiment, a washer roller 159 may be provided that presses the first sidewall rubber 90 and the second sidewall rubber 91 that are stacked on top of each other, the washer roller 159 having a support shaft 159a and a plurality of washers 159b arranged along the support shaft 159a, and each of the plurality of washers 159b may be supported on the support shaft 159a so as to be displaceable in the axial radial direction of the support shaft 159a independently of the other washers 159b.

The washer roller 159 displaces to follow the shape of the first sidewall rubber 90 and the second sidewall rubber 91 when they are stacked together, so pressure can be applied evenly to match the uneven shape of the sidewall rubber 9, making it possible to prevent air pockets from forming.

Although not particularly limited, the manufacturing method of this embodiment may include a step of forming a through hole 9 c reaching the first sidewall rubber 90 in the second sidewall rubber 91 in a state where it is superimposed on the first sidewall rubber 90.
Although not particularly limited, the manufacturing apparatus of this embodiment may be equipped with a needle 200 that forms a through hole 9c reaching the first sidewall rubber 90 by piercing the second sidewall rubber 91 that is superimposed on the first sidewall rubber 90.

By forming the through holes 9c in this way, it becomes possible to release air, especially during vulcanization.

Although the embodiments of the present disclosure have been described above with reference to the drawings, the specific configuration should not be considered to be limited to these embodiments. The scope of the present disclosure is indicated not only by the description of the above embodiments but also by the claims, and further includes all modifications within the meaning and scope equivalent to the claims.

For example, the order of execution of each process, such as operations, procedures, steps, and stages, in the devices, systems, programs, and methods shown in the claims, specifications, and drawings, can be realized in any order, so long as the output of a previous process is not used in a subsequent process. Even if the flow in the claims, specifications, and drawings is explained using "first," "next," etc. for convenience, this does not mean that it is necessary to execute the processes in this order.

The structures employed in each of the above embodiments can be employed in any other embodiment. The specific configurations of each part are not limited to the above-mentioned embodiments, and various modifications are possible without departing from the spirit of this disclosure.

4...Carcass (rubber component of tire), 5...Inner liner rubber (rubber component of tire), 50...Molding drum, 57...First guide, 58...Second guide, 9...Sidewall rubber, 9a...Cutting surface, 90...First sidewall rubber, 91...Second sidewall rubber, 159...Washer roller, 159a...Support shaft, 159b...Washer, DD...Thickness direction, AD...Drum axial direction.

Claims (6)

a step of overlapping a first sidewall rubber with a second sidewall rubber having a width shorter than that of the first sidewall rubber in the axial direction of a molding drum;
a step of winding the first sidewall rubber and the second sidewall rubber in a superimposed state around a tire constituent rubber member on the building drum by one circumference of the tire;
Including,
the first sidewall rubber has a first region overlapped by the second sidewall rubber and a second region not overlapped by the second sidewall rubber,
the second portion has a third portion that is thicker than a maximum thickness of the first portion;
the second region has a fourth region between the first region and the third region, the fourth region being thinner than a maximum thickness of the first region. cutting the first sidewall rubber and the second sidewall rubber in an overlapped state to a length corresponding to one circumference of the tire,
a portion in which the combined thickness of the first sidewall rubber and the second sidewall rubber is 10 mm or more;
The method according to claim 1 , wherein an angle of the cut surface of the first sidewall rubber and the cut surface of the second sidewall rubber with respect to the thickness direction is 0 degrees or more and 30 degrees or less. a step of guiding an end of the first sidewall rubber in the drum axial direction, the end being conveyed toward the molding drum, by a first guide;
and guiding an end of the second sidewall rubber in the drum axial direction, the end being conveyed toward the molding drum, with a second guide,
the first guides are arranged in a pair on both sides of the first sidewall rubber in the drum axial direction and are parallel to a conveying direction of the first sidewall rubber,
The method according to claim 1 or 2 , wherein the second guides are arranged in a pair on both sides of the second sidewall rubber in the drum axial direction and are parallel to a conveying direction of the second sidewall rubber. The method according to any one of claims 1 to 3, wherein a plurality of grooves extending in the drum axial direction are formed in a contact area of the first sidewall rubber with the second sidewall rubber in a step before the first sidewall rubber and the second sidewall rubber are overlapped. The method includes a step of pressing the first sidewall rubber and the second sidewall rubber, which are overlapped with each other, with a washer roller,
The method according to any one of claims 1 to 4, wherein the washer roller has a support shaft and a plurality of washers arranged along the support shaft, and each of the plurality of washers is supported on the support shaft so as to be displaceable in an axial radial direction of the support shaft independently of the other washers. The method according to any one of claims 1 to 5 , further comprising the step of forming a through hole reaching said first sidewall rubber in said second sidewall rubber in a state where said second sidewall rubber is superimposed on said first sidewall rubber.