JP2014133330A - Motorcycle tire, and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance motorcycle tire that is improved in uniformity by suppressing a shape change of a belt in the vulcanization, thereby suppressing a disorder of a belt end.SOLUTION: A method of manufacturing a motorcycle tire of the present invention is characterized by including: a step of forming a green case on a molding drum in which an outer circumferential surface has a shape corresponding to the shape of a tread molding surface of a mold for use in the vulcanization molding; a step of inflating and expanding the green case; a step of directly winding a strip made by rubber coating at least one cord on the green case that is expanded, and forming a belt; a step of forming a green tire by winding a tread around an outer circumference of a belt; and a step of forming a tire by vulcanizing and molding the green tire. The motorcycle tire of the present invention is manufactured by the above manufacturing method.

Description

  The present invention relates to a motorcycle tire and a manufacturing method thereof, and more particularly to a motorcycle tire having an improved belt structure and a manufacturing method thereof.

  Conventionally, in the production of motorcycle tires, tire components such as bead cores, carcass, and sidewall rubber are pasted to form a raw case, and the raw case is expanded by a bladder or the like at an expansion rate of about 8%. Then, a tire component such as a belt or a tread is attached to the expanded raw case with a stitcher or the like to form a raw tire, and the raw tire is vulcanized to produce a tire (for example, Patent Document 1).

  Here, conventionally, a belt to be attached to a green case has been formed by using a flat drum and an interdigital belt member (mainly a kevlar formed by inclining at an angle of about 20 ° with respect to the circumferential direction of the drum. Use) was wrapped around the drum. That is, the belt member is wound so that the belt has a predetermined width, and when the predetermined width is reached, the belt member is folded back to the opposite side in the axial direction of the drum. The slant belt was molded.

JP 2010-253836 A

  However, the conventional tire manufacturing method described above has a problem that the belt and the tread have a large shape change in the subsequent tire vulcanization process due to restrictions on the structure and manufacturing. That is, in the above method, a belt is formed using a flat drum, and a tread is wound around the belt. Therefore, as schematically shown in FIG. On the other hand, in the case of a motorcycle tire, the tread shape after vulcanization is narrowed down to a cubic curved surface with a small curvature radius while the shape has a large curvature radius. That is, as schematically shown in FIG. 1, since the outer periphery after vulcanization molding is smaller than the outer periphery in the raw tire state at the end portion (shoulder portion) of the tread, the expansion rate during vulcanization is set to a negative value. On the other hand, in the center portion (center portion) of the tread, the expansion rate is set to be large in order to narrow down the shoulder portion. As a result, the expansion rate varies on the circumference, and the tire uniformity tends to deteriorate.

Further, particularly in the shoulder portion, since the difference in shape (size of the outer periphery) before and after vulcanization is large, as shown in FIG. .
This has caused a problem that, particularly in motorcycle tires, the tread end side becomes a ground contact surface during cornering, so that stable performance cannot be obtained due to the disturbance of the belt angle.

  The present invention is intended to solve the above-described problem, and is a high-performance motorcycle that suppresses belt shape changes during vulcanization, suppresses belt end disturbance, and improves uniformity. An object is to provide a tire.

The gist configuration of the present invention is as follows.
(1) forming a raw case on a molding drum whose outer peripheral surface has a shape corresponding to the shape of the tread surface molding surface of the mold used during vulcanization molding;
Inflating and expanding the raw case;
Forming a belt by directly wrapping a strip formed by rubber-covering at least one cord on the expanded raw case;
Winding a tread around the outer periphery of the belt and forming a green tire;
Vulcanizing the raw tire using the mold, and molding the tire;
The manufacturing method of the tire for motorcycles characterized by including these.

(2) The method for manufacturing a tire for a motorcycle according to (1), wherein the outer peripheral surface of the molding drum has a curvature radius of 40 mm or more and 200 mm or less in the axial section of the molding drum.

(3) The step of forming the belt is performed when the strip is wound with the cord inclined at an angle of 10 ° or more and 40 ° or less with respect to the circumferential direction of the raw case, and wound to a position that becomes the belt end. The method for manufacturing a tire for a motorcycle according to the above (1) or (2), wherein the winding is repeated while being folded back to the opposite side in the axial direction of the raw case.

(4) In the step of forming the belt, the strip is wound so that the cord returns to the same position in the axial direction when the cord makes one turn on the circumference of the raw case. The manufacturing method of the tire for motorcycles as described in any one.

(5) The motorcycle according to any one of (1) to (4), wherein in the belt forming step, the winding of the strip is repeated to form two or more inclined belts intersecting each other between layers. Tire manufacturing method.

(6) A motorcycle tire manufactured by the motorcycle tire manufacturing method according to any one of (1) to (5) above.

(7) The tire for a motorcycle according to (6), wherein the tire includes two or more inclined belts that intersect each other between layers.

  ADVANTAGE OF THE INVENTION According to this invention, the high-performance motorcycle tire which suppressed the belt shape change at the time of vulcanization, suppressed disturbance of the belt edge part, and improved the uniformity can be provided.

It is a figure for demonstrating the deformation | transformation at the time of vulcanization | cure by the conventional manufacturing method. It is a figure for demonstrating the belt property of the tire manufactured with the conventional manufacturing method. It is a figure for demonstrating the deformation | transformation at the time of vulcanization | cure in the manufacturing method of this invention. (A) It is a figure for demonstrating the process of shape | molding a belt. (B) It is a top view which shows belt property. It is a figure for demonstrating the belt property of the tire manufactured by the manufacturing method of this invention.

<Method for manufacturing motorcycle tires>
Hereinafter, a motorcycle manufacturing method (hereinafter referred to as a tire) according to an embodiment of the present invention will be described in detail with reference to the drawings.
In the present embodiment, first, a tire constituting member such as a bead core, a carcass, a sidewall rubber, or the like is pasted on a molding drum to mold a raw case. The raw case is not limited to the above example, and can also include components such as an inner liner.
Here, in the present invention, it is important that the outer peripheral surface of the molding drum has a shape corresponding to the shape of the tread surface of the mold used during vulcanization molding.

Specifically, the radius of curvature when the tread surface molding surface of the mold used during vulcanization molding is viewed in the axial cross section of the mold, and the radius of curvature of the outer peripheral surface of the molding drum in the axial cross section of the molding drum, Are approximately equal.
More specifically, the curvature radius of the outer peripheral surface of the molding drum in the axial section of the molding drum is preferably 40 mm or more and 200 mm or less.

  Next, the formed raw case is expanded and deformed by being inflated with a bladder or the like.

  Then, as shown in FIG. 4 (a), the expanded raw case 1 is formed by stripping at least one cord 2 with rubber coating (in the example shown, four cords 2 are rubber-covered). The belt 3 is formed by directly winding the strip 3). The material of the belt cord is not particularly limited, and a cord made of organic fibers such as Kevlar can be used.

Specifically, as shown in FIG. 4 (a), the cord 2 (strip 3) is wound while being inclined with respect to the circumferential direction of the raw case 1 until the belt ends (the desired belt width is obtained). Fold back to the opposite side of the raw case in the axial direction. That is, the winding is repeated in the circumferential direction with substantially the same inclination angle as before the turn-up and in the axial direction in the opposite direction.
Here, the inclination angle of the cord 2 with respect to the circumferential direction of the raw tire 1 is preferably 10 ° or more and 40 ° or less.
Further, when winding the cord 2 (strip 3) around the raw case 1, the inclination angle with respect to the circumferential direction of the cord 2 is adjusted so that the cord 2 is located at the same position in the axial direction when the cord 2 makes one round on the circumference of the raw case 1. It is preferable to wind it back.
And as shown in FIG.4 (b), it is preferable to form the inclined belt of two or more layers which mutually cross | intersect between layers by repeating winding of the above-mentioned code | cord | chord 2 (strip 3).

  Next, a green tire is formed by winding a tread around the outer periphery of the formed belt.

  Then, the molded raw tire is vulcanized and molded using a mold having the above-described shape to form a tire.

According to the present invention, as schematically shown in FIG. 3, since the shape of the green tire is close to the shape of the mold, deformation during vulcanization molding is suppressed, and as shown in FIG. It is possible to manufacture a tire with improved uniformity in which the disturbance of the belt end portion is suppressed.
Furthermore, according to the present invention, since the belt disturbance is suppressed, it is possible to manufacture a tire having excellent performance during turning.

  Further, as described above, in the axial cross section of the molding drum, the outer peripheral surface of the molding drum preferably has a curvature radius of 40 mm or more and 200 mm or less. In a motorcycle tire, when the tread surface molding surface of a mold used at the time of vulcanization molding is viewed in the axial cross section of the mold, the curvature radius of the tread surface molding surface is typically 40 mm or more and 200 mm or less. This is because the shape of the outer peripheral surface of the molding drum is close to the shape of the tread surface molding surface of the mold and is effective in suppressing the deformation during vulcanization molding described above.

Further, as described above, when the strip is wound so that the cord is inclined at an angle of 10 ° to 40 ° with respect to the circumferential direction of the raw case, It is preferable to repeat the winding while turning back in the opposite direction. This is because, as shown in FIGS. 4A and 4B, two or more inclined belt layers in which the cords cross each other can be formed.
And it is preferable to wind the strip so that the cord returns to the same position in the axial direction when the cord makes one round on the circumference of the raw case. This is because the tire uniformity is further improved.

<Motorcycle tires>
As described above, the motorcycle tire of the present embodiment is manufactured by the above-described manufacturing method, the belt end disturbance is suppressed, the uniformity is high, and the tire is excellent in turning performance. is there.
In addition, the motorcycle tire of the present invention preferably has two or more belt layers in which the cords cross each other as shown in FIG. 4B.

In order to confirm the effect of the present invention, the raw case formed using a forming drum having a predetermined radius of curvature corresponding to the shape of the mold is expanded, and a belt is formed by directly winding the strip on the expanded raw case, Further, after forming a green tire by winding a tread, a tire according to the invention example was completed by vulcanization molding using the mold.
Also, as a conventional example, a tire was prepared by winding a strip around a flat drum to form a belt, and attaching a tread around the belt to a preformed green case.

About the tire manufactured by each said manufacturing method of tire size 120 / 70R17, the inclination angle with respect to the tire circumferential direction of the belt in each of the center portion and the shoulder portion was measured.
Further, the camber thrust was measured when each tire was mounted on the applicable rim, the internal pressure was 290 kPa, the load 150 kgf was applied, and the camber angle was 45 °.
Furthermore, each tire is mounted on the applicable rim, the internal pressure is 290 kPa, and it is mounted on a 1000 cc motorcycle. Under the conditions of one person riding, straight running performance (steering stability and riding comfort), turning performance (steering stability and The riding comfort was evaluated. The evaluation is based on a sensitivity evaluation by a driver with a maximum of 10 points, and a larger numerical value indicates better performance.
The evaluation results are shown in Tables 1 and 2 below.

As shown in Table 1, in the tire according to the present invention, it is understood that the disorder of the inclination angle at the belt end is suppressed, and the uniformity is higher than the tire according to the conventional example.
Furthermore, it can be seen that the inventive tire has a larger camber thrust than the conventional tire.
In addition, as shown in Table 2, it can be seen that the inventive tires are superior in steering stability and riding comfort during turning than the conventional tires while maintaining straight running performance equivalent to that of the conventional tires.

1: Raw tire, 2: Cord, 3: Strip

Claims (7)

Forming a raw case on a molding drum whose outer peripheral surface has a shape corresponding to the shape of the tread surface molding surface of the mold used during vulcanization molding;
Inflating and expanding the raw case;
Forming a belt by directly wrapping a strip formed by rubber-covering at least one cord on the expanded raw case;
Winding a tread around the outer periphery of the belt and forming a green tire;
Vulcanizing the raw tire using the mold, and molding the tire;
The manufacturing method of the tire for motorcycles characterized by including these.   The method for manufacturing a tire for a motorcycle according to claim 1, wherein the outer peripheral surface of the molding drum has a curvature radius of 40 mm or more and 200 mm or less in an axial section of the molding drum.   In the step of forming the belt, the strip is wound by inclining the cord at an angle of 10 ° or more and 40 ° or less with respect to the circumferential direction of the raw case, The method for manufacturing a tire for a motorcycle according to claim 1 or 2, wherein the winding is repeated while being folded back to the opposite side of the raw case in the axial direction.   The step of forming the belt includes winding the strip so that the cord returns to the same position in the axial direction when the cord makes one turn on the circumference of the raw case. Of manufacturing tires for motorcycles.   The method for manufacturing a tire for a motorcycle according to any one of claims 1 to 4, wherein the belt forming step repeats winding of the strip to form two or more inclined belts intersecting each other between layers.   A motorcycle tire manufactured by the method for manufacturing a motorcycle tire according to any one of claims 1 to 5.   The motorcycle tire according to claim 6, wherein the tire includes two or more inclined belts intersecting each other between layers.

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