JP7413719B2 - Tread rubber forming method and tread rubber forming device - Google Patents

Description

The present invention relates to a technique for forming an annular tread rubber by spirally winding tape-shaped unvulcanized rubber strips.

BACKGROUND ART Conventionally, a technique is known in which a tread rubber without joints is formed by spirally wrapping rubber strips to improve the uniformity of a tire (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2015-229438

Incidentally, in recent years, in order to improve the fuel efficiency of automobiles, tires using silica as a reinforcing agent for tread rubber have been proposed. Since this silica has high electrical insulating properties, it causes an increase in the electrical resistance of the tire, and static electricity accumulates in the vehicle, which may cause radio interference such as radio noise.

Therefore, a technique is being considered that uses conductive rubber that penetrates through the tread rubber to create electrical continuity between the radially inner and radially outer sides of the tread rubber, thereby discharging the electric charge accumulated in the tire.

However, the tread rubber through which the conductive rubber is penetrated has a more complicated structure than normal tread rubber, resulting in poor productivity. In particular, in the method of forming tread rubber by spirally wrapping rubber strips extruded from a gear pump, it is difficult to sufficiently increase the extrusion capacity of the gear pump. It requires a lot of time.

The present invention was devised in view of the above-mentioned circumstances, and provides a technology that can form tread rubber in a short time that can discharge the electric charge accumulated in the tire while improving the fuel efficiency and uniformity of the tire. That is the main purpose.

A first aspect of the present invention is a method of forming an annular tread rubber by spirally winding tape-shaped unvulcanized rubber strips, the method comprising: forming an insulating first rubber strip at least on the tread rubber; a first step of rolling the electrically conductive second rubber strip while moving it in the first axial direction; a second step of wrapping the first rubber strip around the outer peripheral surface; and a second step of wrapping the third insulating rubber strip around a part of the second rubber strip from a position on the second axial side with respect to the second rubber strip. a third step of rolling the tread rubber so that it is exposed on the outside in the radial direction of the tread rubber; and a fourth step of rolling an insulating fourth rubber strip on the side of the first axial direction or the second axial direction with respect to the second rubber strip. and a fourth step of rolling the second rubber strip so that a portion of the second rubber strip is exposed outside in the radial direction of the tread rubber while moving the second rubber strip from the position in at least the second axial direction.

In the tread rubber forming method according to the first invention, the first rubber strip, the second rubber strip, and the fourth rubber strip are made of a rubber material having a volume resistivity of 1×10 ⁸ Ωcm or more after vulcanization. Preferably, the second rubber strip is made of a rubber material having a volume resistivity of 1×10 ⁷ Ωcm or less after vulcanization.

In the tread rubber forming method according to the first aspect of the present invention, it is desirable that the second step starts before the first step ends.

In the tread rubber forming method according to the first aspect of the present invention, it is desirable that the third step starts before the second step ends.

In the tread rubber forming method according to the first invention, the fourth rubber strip is wound over the first rubber strip in the first axial direction, and before the first step is completed, the fourth rubber strip is rolled over the first rubber strip in the first axial direction. It is desirable that the fourth step begins.

In the tread rubber forming method according to the first aspect of the present invention, it is preferable that in the third step, the third rubber strip is rolled up while moving at least in the first axial direction.

In the tread rubber forming method according to the first invention, the fourth rubber strip is wound between the second rubber strip and the third rubber strip, and the fourth rubber strip is wound over the second rubber strip before the third step is finished. It is desirable that four steps are started.

In the tread rubber forming method according to the first aspect of the present invention, it is preferable that in the third step, the third rubber strip is rolled up while moving at least in the second axial direction.

In the tread rubber forming method according to the first aspect of the present invention, it is preferable that the first step includes a step of rolling the first rubber strip overlappingly while moving the first rubber strip in the second axial direction.

In the tread rubber forming method according to the first aspect of the present invention, it is preferable that the third step includes a step of rolling the third rubber strip overlappingly while moving the third rubber strip in the second axial direction.

In the tread rubber forming method according to the first aspect of the present invention, it is preferable that the third step includes a step of rolling the third rubber strip overlappingly while moving the third rubber strip in the first axial direction.

In the tread rubber forming method according to the first aspect of the present invention, it is preferable that the fourth step includes a step of rolling the fourth rubber strip overlappingly while moving the fourth rubber strip in the first axial direction.

A second aspect of the present invention is an apparatus for forming an annular tread rubber by spirally winding tape-shaped unvulcanized rubber strips, the device moving at least in the first axial direction of the tread rubber. a first applicator for supplying a first insulating rubber strip to a first winding position; a second applicator for supplying a second insulating rubber strip to a second winding position; a third applicator that supplies the rubber strip to a third winding position such that a portion of the rubber strip is exposed radially outwardly of the tread rubber; and a fourth applicator positioned on a side of the direction of the second axis, the fourth applicator supplying a fourth insulating rubber strip to a fourth winding position while moving in at least the second axis direction.

In the tread rubber forming method of the first invention, the insulating rubber strip is spirally wound in the first step, the third step and the fourth step, and the conductive rubber strip is rolled up in the second step. The second rubber strip is wrapped. A portion of the second rubber strip is exposed inside the tread rubber in the radial direction, and another portion is exposed outside the tread rubber in the radial direction. As a result, the tread rubber is formed which can discharge the electric charge accumulated in the tire while improving the fuel efficiency of the tire.

In this tread rubber forming method, tread rubber is formed in a dispersed manner in the first step to the fourth step. Further, some of the first to fourth steps can be performed simultaneously. Therefore, the tread rubber can be formed in a short time.

In the tread rubber forming device of the second invention, the insulating rubber strip is spirally wound using the first applicator, the third applicator, and the fourth applicator, and the second applicator The second electrically conductive rubber strip is wrapped around the conductive rubber strip. A portion of the second rubber strip is exposed inside the tread rubber in the radial direction, and another portion is exposed outside the tread rubber in the radial direction. As a result, the tread rubber is formed which can discharge the electric charge accumulated in the tire while improving the fuel efficiency of the tire.

In this tread rubber forming method, tread rubber is dispersed and formed using the first to fourth applicators. The first to fourth applicators can partially operate simultaneously. Therefore, the tread rubber can be formed in a short time.

1 is a cross-sectional view of tread rubber formed by the tread rubber forming method and tread rubber forming apparatus of the present invention. 1 is a flowchart showing the steps of a tread rubber forming method according to an embodiment of the present invention. FIG. 1 is a side view showing the configuration of a tread rubber forming device according to an embodiment of the present invention. It is a schematic diagram showing the above-mentioned tread rubber forming device in a first step. It is a schematic diagram showing the above-mentioned tread rubber forming device in a second step. It is a schematic diagram showing the above-mentioned tread rubber forming device in a third process. It is a schematic diagram which shows the said tread rubber forming apparatus in a 4th process. It is a schematic diagram which shows the modification of the said tread rubber forming apparatus in a 3rd process. It is a schematic diagram which shows the modification of the said tread rubber forming apparatus in a 4th process. It is a sectional view showing an example of tread rubber formed using a modification of the above-mentioned tread rubber forming device.

Hereinafter, one embodiment of the present invention will be described based on the drawings.
FIG. 1 is a cross-sectional view of the tread rubber of a tire formed by the tread rubber forming method and tread rubber forming apparatus of this embodiment. The tread rubber 1 is formed into an annular shape and includes an insulating part 2 having electrical insulation properties and a conductive part 3 having electrical conductivity. The conductive part 3 is formed by penetrating the insulating part 2 in the thickness direction (radial direction) of the tread rubber 1.

The insulating portion 2 is made of, for example, rubber containing a large amount of silica as a reinforcing agent. In the present tread rubber, the insulating portion 2 is desirably made of a rubber material having a volume resistivity of 1×10 ⁸ Ωcm or more after vulcanization. The conductive portion 3 is made of, for example, rubber containing a large amount of carbon as a reinforcing agent. In the present tread rubber, the conductive portion 3 is desirably made of a rubber material having a volume resistivity of 1×10 ⁷ Ωcm or less after vulcanization. Note that the volume resistivity can be measured, for example, using an electrical resistance measuring device using a rubber sample measuring 15 cm square and 2 mm thick under conditions of an applied voltage of 500 V, an air temperature of 25° C., and a humidity of 50%.

The conductive portion 3 penetrating the insulating portion 2 establishes conduction between the radially inner side and the radially outer side of the tread rubber 1. Conductive rubber, such as topping rubber or sidewall rubber of a belt member, is disposed inside the tread rubber 1 in the radial direction, so that electrical charges accumulated in the tire are discharged via the conductive part 3. .

FIG. 2 is a flowchart showing the procedure of the tread rubber forming method of this embodiment. Moreover, FIG. 3 shows an example of a tread rubber forming apparatus suitably used in the tread rubber forming method.

As shown in FIG. 2, the present tread rubber forming method includes a first step S1 of winding a first insulating rubber strip 11, a second step S2 of winding a second conductive rubber strip 12, and a second step S2 of winding a second conductive rubber strip 12. (For the first rubber strip 11 to the fourth rubber strip 14, (See Figures 4 to 10). The first rubber strip 11, the third rubber strip 13, and the fourth rubber strip 14 form an insulating part 2, and the second rubber strip 12 forms a conductive part 3.

As shown in FIG. 3, the tread rubber forming device 100 includes a first applicator 101 that supplies a first rubber strip 11 to a first winding position, and a second applicator that supplies a second rubber strip 12 to a second winding position. It includes an applicator 102, a third applicator 103 that supplies the third rubber strip 13 to the third winding position, and a fourth applicator 104 that supplies the fourth rubber strip 14 to the fourth winding position.

The first rubber strip 11 to the fourth rubber strip 14 are wound around the radially outer side of a rotatably driven forming drum 105, and constitute an annular tread rubber 1. The first applicator 101, the third applicator 103, and the fourth applicator 104 are configured to be movable in the axial direction of the forming drum 105 (in the direction perpendicular to the paper surface in FIG. 3). That is, the first applicator 101, the third applicator 103, and the fourth applicator 104 are configured to be movable in the first axial direction of the tread rubber 1 or in the second axial direction opposite to the first axial direction. . The forming drum 105 may be configured to be movable in its axial direction. Further, the first applicator 101, the second applicator 102, the third applicator 103, and the fourth applicator 104 are configured to be movable in the front-rear direction perpendicular to the axial direction of the forming drum 105, as necessary. You can.

A known rubber strip supply device may be applied to the first applicator 101 to the fourth applicator 104. For example, the first applicator 101 is configured by a device having a belt for conveying the first rubber strip 11 and a roller for pressing the winding portion of the first rubber strip 11 inward in the radial direction of the forming drum 105. sell. The configurations of the second applicator 102 to the fourth applicator 104 are also similar to the first applicator 101.

For example, a gear pump (not shown) is provided upstream of the first applicator 101, the third applicator 103, and the fourth applicator 104. The gear pump continuously and stably supplies the first rubber strip 11, the third rubber strip 13, and the fourth rubber strip 14, even if the rubber material is difficult to mix, process, and apply, and can be easily rolled up. It is. Upstream of the second applicator 102, for example, a drum or bobbin (not shown) around which the second rubber strip 12 is wound is provided.

The rotation of the forming drum 105 and the movement of the first applicator 101, the third applicator 103, the fourth applicator 104, and the forming drum 105 are controlled by a control unit (not shown). The control unit synchronously controls the first applicator 101 or the like or the forming drum 105. Hereinafter, a configuration in which the first applicator 101, third applicator 103, and fourth applicator 104 are movable will be described, but the same applies to a configuration in which the forming drum 105 is movable.

FIG. 4 shows the tread rubber forming apparatus 100 in the first step S1. In the first step S1, the first applicator 101 supplies the first rubber strip 11 to the first winding position P1 while moving in the first axial direction D1 of the tread rubber 1. As a result, the first rubber strip 11 is wound while moving in the first axial direction D1. Note that, for convenience of explanation, the first axial direction D1 is the right direction in FIG. 4, but it may be the left direction. Although the cross-sectional profile of the first rubber strip 11 wound over the other depends on the cross-sectional profile of the tread rubber 1, in this embodiment, the first rubber strip 11 has a flat part at the center and sloped parts at both ends.

FIG. 5 shows the tread rubber forming apparatus 100 in the second step S2. In the second step S2, the second applicator 102 supplies the second rubber strip 12 to the second winding position P2. As a result, the second rubber strip 12 is wound. The second winding position P2 is located closer to the second axial direction D2, which is opposite to the first axial direction D1, than the first winding position P1.

In this embodiment, the width of the second rubber strip 12 is configured to correspond to the width of the conductive part 3. The width of the second rubber strip 12 may be smaller than the width of the conductive part 3. In this case, for example, while the second applicator 102 moves in the first axial direction D1 of the tread rubber 1, the second rubber strip 12 is wound in a spiral manner, thereby forming the conductive portion 3.

In the second step S2, the edge of the second rubber strip 12 in the second axial direction D2 is positioned closer to the second axial direction D2 than the edge of the first rubber strip 11 in the second axial direction D2. A second winding position P2 is set. As a result, the end edge of the second rubber strip 12 in the second axial direction D2 is exposed inside the tread rubber 1 in the radial direction.

Further, the second winding position P2 is set such that the end edge of the second rubber strip 12 in the first axial direction D1 is located outside the first rubber strip 11 in the radial direction of the tread rubber. In this embodiment, the first axial direction D1 of the second rubber strip 12 extends beyond the slope of the first rubber strip 11 and extends over the flat portion.

FIG. 6 shows the tread rubber forming apparatus 100 in the third step S3. In the third step S3, the third applicator 103 positioned on the second axial direction D2 side with respect to the second applicator 102 (see FIG. 5) moves the third rubber strip while moving in the first axial direction D1. 13 is supplied to the third winding position P3. As a result, the third rubber strip 13 is wound while moving in the first axial direction D1. Furthermore, by moving the third rubber strip 13 in the first axial direction D1, the third rubber strip 13 is wound on the outer side in the radial direction of the second rubber strip 12, and the third rubber strip 13 is rolled over the second rubber strip 12 in the second axial direction. A third rubber strip 13 is formed on the D2 side.

In the third step S3, the third winding position P3 is set such that the third rubber strip 13 is located at least closer to the second axial direction D2 than the edge of the second rubber strip 12 on the first axial direction D1. It is set. As a result, the third rubber strip 13 is wound so that a portion of the second rubber strip 12 is exposed on the outside in the radial direction of the tread rubber 1. Note that in the third step S3, the third rubber strip 13 may be wound using the first applicator 101 or the fourth applicator 104.

FIG. 7 shows the tread rubber forming apparatus 100 in the fourth step S4. In the present tread rubber forming apparatus 100, the fourth applicator 104 is located on the first axial direction D1 side with respect to the first applicator 101 and the second applicator 102 (see FIGS. 4 and 5).

In the fourth step S4, the fourth applicator 104, which is positioned on the side in the first axial direction D1 with respect to the first applicator 101, wraps the fourth rubber strip 14 a fourth time while moving in the second axial direction D2. It is supplied to position P4. As a result, the fourth rubber strip 14 is rolled up while moving in the second axial direction D2, and the first rubber strip 11 and the fourth rubber strip 14 are formed on the side in the first axial direction D1 relative to the second rubber strip 12. be done.

In the fourth step S4, the end edge of the fourth rubber strip 14 on the second axial direction D2 side is at least closer to the first axial direction D1 side than the end edge of the second rubber strip 12 on the first axial direction D1 side. The fourth winding position P4 is set such that Thereby, the fourth rubber strip 14 is wound so that a part of the second rubber strip 12 is exposed to the outside in the radial direction of the tread rubber 1. Note that in the fourth step S4, the fourth rubber strip 14 may be wound using the first applicator 101 or the third applicator 103.

In this tread rubber forming method, a first insulating rubber strip 11, a third rubber strip 13, and a fourth rubber strip 14 are wound in a spiral manner in a first step S1, a third step S3, and a fourth step S4. , a second conductive rubber strip 12 is wound in a second step S2. A part of the second rubber strip 12 (the end on the side in the second axial direction D2) is exposed inside the radial direction of the tread rubber 1, and the other part (the end on the side in the first axial direction D1) It is exposed on the outside in the radial direction of the tread rubber 1. As a result, the tread rubber 1 is formed that can discharge the electric charge accumulated in the tire while improving the fuel efficiency of the tire.

In this tread rubber forming method, the tread rubber 1 is formed in a dispersed manner in the first step S1 to the fourth step S4. As described later, some of the first step S1 to the fourth step S4 can be performed simultaneously. Therefore, the tread rubber 1 capable of discharging the electric charge accumulated in the tire can be formed in a short time. In particular, even if a gear pump with poor rubber strip supply capacity is applied, the tread rubber 1 can be formed in a short time.

This tread rubber forming device 100 uses a first applicator 101, a third applicator 103, and a fourth applicator 104 to form an insulating first rubber strip 11, a third rubber strip 13, and a fourth rubber strip 14 in a spiral manner. A second electrically conductive rubber strip 12 is applied using a second applicator 102. A portion of the second rubber strip 12 is exposed on the inside of the tread rubber 1 in the radial direction, and another portion is exposed on the outside of the tread rubber 1 in the radial direction. As a result, the tread rubber 1 is formed that can discharge the electric charge accumulated in the tire while improving the fuel efficiency of the tire.

In the present tread rubber forming apparatus 100, the tread rubber 1 is formed in a dispersed manner using the first applicator 101 to the fourth applicator 104. The first to fourth applicators 101 to 104 can partially operate simultaneously. Therefore, the tread rubber 1 capable of discharging the electric charge accumulated in the tire can be formed in a short time.

As explained below, in the present tread rubber forming method, the first step S1, the second step S2, the third step S3, and the fourth step S4 do not necessarily have to be performed in the order shown in FIG. 2.

In the present tread rubber forming method, it is desirable that the second step S2 is started before the first step S1 is finished. For example, after the end edge of the first rubber strip 11 on the second axial direction D2 side passes the end edge of the second winding position P2 on the first axial direction D1 side in the first step S1, the second rubber strip 12 Winding may begin. In such a configuration, the first step S1 and the second step S2 partially proceed simultaneously, and the production efficiency of the tread rubber 1 is improved.

In the present tread rubber forming method, it is desirable that the third step S3 is started before the second step S2 is finished. For example, the configuration may be such that the third step S3 starts before the second step S2 starts. In this case, before the end edge of the third rubber strip 13 on the first axial direction D1 side reaches the end edge of the second winding position P2 on the first axial direction D1 side in the third step S3, the second step S3 is performed. It is sufficient if S2 is completed. In such a configuration, the second step S2 and the third step S3 partially proceed simultaneously, and the production efficiency of the tread rubber 1 is improved.

In the present tread rubber forming method, it is desirable that the fourth step S4 starts before the first step S1 ends. For example, before the end edge of the fourth rubber strip 14 on the second axial direction D2 side reaches the end edge of the first winding position P1 on the first axial direction D1 side in the fourth step S4, the first step S1 It is sufficient if it has been completed. In such a configuration, the first step S1 and the fourth step S4 partially proceed simultaneously, and the production efficiency of the tread rubber 1 is improved.

8 and 9 show a tread rubber forming apparatus 100A that is a modification of the tread rubber forming apparatus 100. The present tread rubber forming device 100A is characterized in that the fourth applicator 104 is located on the second axial direction D2 side with respect to the first applicator 101 and the second applicator 102 (see FIGS. 4 and 5). , is different from the tread rubber forming apparatus 100.

For parts of the tread rubber forming apparatus 100A that are not explained below, the configuration of the tread rubber forming apparatus 100 described above may be adopted. That is, in the present tread rubber forming apparatus 100A, the first step S1 and the second step S2 are performed similarly to FIGS. 4 and 5.

FIG. 8 shows the tread rubber forming apparatus 100A in the third step S3. In the third step S3, the third applicator 103, which is positioned on the second axial direction D2 side with respect to the second applicator 102, wraps the third rubber strip 13 around the third rubber strip 13 while moving in the second axial direction D2. It is supplied to position P3. As a result, the third rubber strip 13 is wound while moving in the second axial direction D2.

In the third step S3 of the tread rubber forming method using the tread rubber forming apparatus 100A, the third rubber strip 13 is at least wider in the second axial direction D2 than the edge of the second rubber strip 12 on the second axial direction D2 side. The third winding position P3 is set to be located on the side. As a result, the third rubber strip 13 is wound on the second axial direction D2 side with a distance from the second rubber strip 12, and the entire second rubber strip 12 is exposed to the outside of the tread rubber 1 in the radial direction.

In addition, in the third step S3 of the tread rubber forming method using the tread rubber forming apparatus 100A, the third applicator 103 supplies the third rubber strip 13 to the third winding position P3 while moving in the first axial direction D1. It may be configured to do so. As a result, the third rubber strip 13 is wound while moving in the first axial direction D1.

FIG. 9 shows the tread rubber forming apparatus 100A in the fourth step S4. In the present tread rubber forming apparatus 100A, the fourth applicator 104 is located on the second axial direction D2 side with respect to the second applicator 102 and the first applicator 101, and on the first side with respect to the third applicator 103. It is located on the side in the axial direction D1. Thereby, the fourth rubber strip 14 is wound between the second rubber strip 12 and the third rubber strip 13.

In the fourth step S4, the fourth applicator 104 positioned on the second axial direction D2 side with respect to the second applicator 102 wraps the fourth rubber strip 14 a fourth time while moving in the second axial direction D2. It is supplied to position P4. As a result, the fourth rubber strip 14 is rolled up while moving in the second axial direction D2, and the third rubber strip 13 and the fourth rubber strip 14 are formed on the second axial direction D2 side than the second rubber strip 12. be done.

In the fourth step S4, the fourth winding position P4 is set such that the fourth rubber strip 14 is located at least closer to the second axial direction D2 than the edge of the second rubber strip 12 on the second axial direction D2. It is set. Thereby, the fourth rubber strip 14 is wound so that a part of the second rubber strip 12 is exposed to the outside in the radial direction of the tread rubber 1. Also in the tread rubber forming device 100A, a part of the second rubber strip 12 (the end on the second axial direction D2 side) is exposed inside the radial direction of the tread rubber 1, and another part (the end on the first axial direction D1 side end) is exposed to the outside in the radial direction of the tread rubber 1.

Also in the tread rubber forming method using the present tread rubber forming apparatus 100A, the tread rubber 1 is formed in a dispersed manner in the first step S1 to the fourth step S4. Part of the first step S1 to the fourth step S4 can be performed simultaneously. Therefore, the tread rubber 1 capable of discharging the electric charge accumulated in the tire can be formed in a short time.

Even in the tread rubber forming method using the present tread rubber forming apparatus 100A, the first step S1, the second step S2, the third step S3, and the fourth step S4 are not necessarily performed in the order shown in FIG. You can. Preferably, the second step S2 is started before the first step S1 ends. Further, it is desirable that the third step S3 is started before the second step S2 ends.

In the present tread rubber forming method, it is desirable that the fourth step S4 is started before the third step S3 is finished. For example, before the end edge of the fourth rubber strip 14 on the second axial direction D2 side reaches the end edge of the third winding position P3 on the first axial direction D1 side in the fourth step S4, the third step S3 It is sufficient if it has been completed. In such a configuration, the third step S3 and the fourth step S4 partially proceed simultaneously, and the production efficiency of the tread rubber 1 is improved.

The first step S1 shown in FIG. 4 is preferably configured to include a step of rolling the first rubber strip 11 overlappingly while moving it in the second axial direction D2. For example, the first rubber strip 11 is rolled up while being moved in the first axial direction D1 at the first winding position P1, and then folded back at the end on the first axial direction D1 side of the first winding position P1, and then While moving in two axial directions D2, the windings are overlapped so as to end before the second winding position P2. Thereby, the volume of the insulating rubber at the first winding position P1 can be easily ensured.

The third step S3 shown in FIG. 6 is desirably configured to include a step of rolling the third rubber strip 13 overlappingly while moving it in the second axial direction D2. For example, the third rubber strip 13 is rolled up while being moved in the second axial direction D2 at the third winding position P3, and then folded back at the end on the second axial direction D2 side of the third winding position P3. It is rolled up while being moved in the uniaxial direction D1. Thereby, the volume of the insulating rubber at the third winding position P3 can be easily ensured.

The third step S3 shown in FIG. 8 is preferably configured to include a step of rolling the third rubber strip 13 overlappingly while moving it in the first axial direction D1. For example, the third rubber strip 13 is rolled up while being moved in the first axial direction D1 at the third winding position P3, and then folded back at the end on the first axial direction D1 side of the third winding position P3, and then It is rolled up while being moved in two axial directions D2. Thereby, the volume of the insulating rubber at the third winding position P3 can be easily ensured.

The fourth step S4 shown in FIG. 7 or 9 is preferably configured to include a step of rolling the fourth rubber strip 14 overlappingly while moving it in the first axial direction D1. For example, the fourth rubber strip 14 is rolled up while being moved in the first axial direction D1 at the fourth winding position P4, and then folded back at the end on the first axial direction D1 side of the fourth winding position P4, and then It is rolled up while being moved in two axial directions D2. Thereby, the volume of the insulating rubber at the fourth winding position P4 can be easily ensured.

FIG. 10 shows a first step S1 including a step of rolling the first rubber strip 11 overlappingly while moving it in the second axial direction D2, and a step of rolling the third rubber strip 13 in the second axial direction D2 using the tread rubber forming apparatus 100A. The tread rubber 1 formed through the third step S3, which includes the step of rolling the rubber while moving it, is shown. In the tread rubber 1 shown in FIG. 10, the volume of the insulating rubber can be easily ensured in the region corresponding to the shoulder portion.

Although the tread rubber forming method and tread rubber forming apparatus 100 of the present invention have been described above in detail, the present invention is not limited to the above-described specific embodiments and can be implemented by changing various aspects. For example, the tread rubber 1 is not limited to being formed on the radially outer side of the forming drum 105, but may also be formed on the radially outer side of a belt member or the like that constitutes a tire.

1 Tread rubber 11 First rubber strip 12 Second rubber strip 13 Third rubber strip 14 Fourth rubber strip 100 Tread rubber forming device 101 First applicator 102 Second applicator 103 Third applicator 104 Fourth applicator D1 1st axial direction D2 2nd axial direction S1 1st process S2 2nd process S3 3rd process S4 4th process

Claims (12)

A method of forming an annular tread rubber by spirally wrapping tape-shaped unvulcanized rubber strips, the method comprising:
a first step of rolling an insulating first rubber strip while moving it at least in the first axial direction of the tread rubber;
a second step of wrapping a second conductive rubber strip around the outer circumferential surface of the first rubber strip from a position on the second axial direction opposite to the first axial direction;
A third insulating rubber strip is wound around the second rubber strip from a position on the second axial side so that a portion of the second rubber strip is exposed to the outside in the radial direction of the tread rubber. 3 steps and
While moving an insulating fourth rubber strip from a position on the first axial direction or the second axial direction with respect to the second rubber strip in at least the second axial direction, one of the second rubber strips is moved. a fourth step of rolling the tread rubber so that the tread rubber is exposed on the outside in the radial direction ;
The second step starts before the first step ends,
Tread rubber forming method. A method of forming an annular tread rubber by spirally wrapping tape-shaped unvulcanized rubber strips, the method comprising:
a first step of rolling an insulating first rubber strip while moving it at least in the first axial direction of the tread rubber;
a second step of wrapping a second conductive rubber strip around the outer circumferential surface of the first rubber strip from a position on the second axial direction opposite to the first axial direction;
A third insulating rubber strip is wound around the second rubber strip from a position on the second axial side so that a portion of the second rubber strip is exposed to the outside in the radial direction of the tread rubber. 3 steps and
While moving an insulating fourth rubber strip from a position on the first axial direction or the second axial direction with respect to the second rubber strip in at least the second axial direction, one of the second rubber strips is moved. a fourth step of rolling the tread rubber so that the tread rubber is exposed on the outside in the radial direction;
The third step starts before the second step ends,
Tread rubber forming method. A method of forming annular tread rubber by spirally winding tape-shaped unvulcanized rubber strips, the method comprising:
a first step of rolling an insulating first rubber strip while moving it at least in the first axis direction of the tread rubber;
a second step of wrapping a second conductive rubber strip around the outer circumferential surface of the first rubber strip from a position on the second axial direction opposite to the first axial direction than the first rubber strip;
A third insulating rubber strip is wound around the second rubber strip from a position on the second axial side so that a portion of the second rubber strip is exposed to the outside in the radial direction of the tread rubber. 3 steps and
While moving an insulating fourth rubber strip from a position on the first axial direction or the second axial direction with respect to the second rubber strip in at least the second axial direction, one of the second rubber strips is moved. a fourth step of rolling the tread rubber so that the tread rubber is exposed on the outside in the radial direction;
The fourth rubber strip is wound over the first rubber strip in the first axial direction, and the fourth step starts before the first step ends.
Tread rubber forming method. A method of forming an annular tread rubber by spirally wrapping tape-shaped unvulcanized rubber strips, the method comprising:
a first step of rolling an insulating first rubber strip while moving it at least in the first axial direction of the tread rubber;
a second step of wrapping a second conductive rubber strip around the outer circumferential surface of the first rubber strip from a position on the second axial direction opposite to the first axial direction;
A third insulating rubber strip is wound around the second rubber strip from a position on the second axial side so that a portion of the second rubber strip is exposed to the outside in the radial direction of the tread rubber. 3 steps and
While moving an insulating fourth rubber strip from a position on the first axial direction or the second axial direction with respect to the second rubber strip in at least the second axial direction, one of the second rubber strips is moved. a fourth step of rolling the tread rubber so that the tread rubber is exposed on the outside in the radial direction;
The fourth rubber strip is wound between the second rubber strip and the third rubber strip, and the fourth step starts before the third step ends.
Tread rubber forming method. A method of forming an annular tread rubber by spirally wrapping tape-shaped unvulcanized rubber strips, the method comprising:
a first step of rolling an insulating first rubber strip while moving it at least in the first axial direction of the tread rubber;
a second step of wrapping a second conductive rubber strip around the outer circumferential surface of the first rubber strip from a position on the second axial direction opposite to the first axial direction;
A third insulating rubber strip is wound around the second rubber strip from a position on the second axial side so that a portion of the second rubber strip is exposed to the outside in the radial direction of the tread rubber. 3 steps and
While moving an insulating fourth rubber strip from a position on the first axial direction or the second axial direction with respect to the second rubber strip in at least the second axial direction, one of the second rubber strips is moved. a fourth step of rolling the tread rubber so that the tread rubber is exposed on the outside in the radial direction;
The fourth step includes the step of rolling the fourth rubber strip while moving it in the first axial direction.
Tread rubber forming method. The first rubber strip, the second rubber strip, and the fourth rubber strip are made of a rubber material having a volume resistivity of 1×10 ⁸ Ωcm or more after vulcanization,
6. The tread rubber forming method according to claim 1, wherein the second rubber strip is made of a rubber material having a volume resistivity of 1×10 ⁷ Ωcm or less after vulcanization. 4. The tread rubber forming method according to claim 3, wherein in the third step, the third rubber strip is wound while being moved at least in the first axial direction . 5. The tread rubber forming method according to claim 4 , wherein in the third step, the third rubber strip is wound while being moved at least in the second axial direction. 9. The tread rubber forming method according to claim 1, wherein the first step includes a step of rolling the first rubber strip overlappingly while moving the first rubber strip in the second axial direction. 7. The third step includes the step of rolling the third rubber strip overlappingly while moving the third rubber strip in the second axial direction.
The tread rubber forming method described. 9. The tread rubber forming method according to claim 8, wherein the third step includes a step of rolling the third rubber strip overlappingly while moving the third rubber strip in the first axial direction. An apparatus for forming annular tread rubber by spirally winding tape-shaped unvulcanized rubber strips, the device comprising:
a first applicator that supplies an insulating first rubber strip to a first winding position while moving in at least a first axial direction of the tread rubber;
a second applicator located on a second axial side opposite to the first axial direction with respect to the first applicator, and supplying a second conductive rubber strip to a second winding position;
A third insulating rubber strip is positioned on the second axial side with respect to the second applicator and moves in at least the first axial direction, so that a portion of the second rubber strip is attached to the tread rubber. a third applicator that supplies the third winding position so as to be exposed radially outwardly;
A fourth insulating rubber strip is supplied to a fourth winding position while being located on the first axial direction or the second axial direction side with respect to the second applicator and moving in at least the second axial direction. and a fourth applicator for
Tread rubber forming equipment.

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