JPH04356202A - Manufacturing method of band layer - Google Patents

Abstract

PURPOSE:To improve the running stability of a motorcycle at a high speed as well as to raise productivity and reduce the cost thereof. CONSTITUTION:This is the method to manufacture a band layer 7 for a motorcycle tire having the band layer 7 arranged in the interior of both a carcass 6 and a tread portion and on the outer side of a carcass 2, where the band layer 7 is formed by band ply pieces 7a, 7b divided into plural number in the tire axis direction and each of band ply pieces 7a, 7b is formed by winding band cords in spiral in a manner inclining in the same direction as that of a band shaped ply 10 embedded in a topping rubber.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a band layer, which improves tire productivity and improves running stability of tires manufactured according to the present invention when running at high speeds.

0002

[Background Art] In recent years, with the development of expressway networks,
Demand for high-speed driving is also increasing for motorcycles.

[0003] Such radial tires for motorcycles have conventionally been designed and manufactured based on radial tires for four-wheeled vehicles, so they have not been able to match the turning performance and straight-line performance unique to motorcycles. First, the steering stability is poor, especially when driving at high speeds.

[0004] The reason for this is that conventionally, the belt layer a provided for reinforcing the tread portion, as in four-wheeled vehicles,
As shown in FIG. 7(A), the cord b is arranged at an angle of 15 to 30 degrees with respect to the tire equator. Code b like this
For example, as shown in FIG. 7(B), the belt layer a with the belt layer a tilted has a belt body d having a cord b extending in the longitudinal direction.
The cord was cut in accordance with the inclination angle α of the cord d to form a parallelogram-shaped block e, and the end edges f and f of the block e were abutted and connected in series to form a band-like shape.

Since the belt layer a formed in this manner is a sheet body, a hoop effect occurs due to the intersection of the carcass and the cord, which increases the rigidity of the tread portion and increases the canvas last necessary for turning at a large camber angle. Not only does this decrease, but also because the abutting portions f and f pass obliquely to the tire rotation direction, the abutting portions do not land at the same time during driving, making handling operation unstable.
Not only does it impede straight-line performance, but it also has poor handling when turning, and these effects are especially noticeable when driving at high speeds.

In order to solve one part of the above-mentioned problems, for example, in Japanese Utility Model Application Publication No. 58-160805, the conventional belt layer or band layer is made to have a cord spirally wound in the direction of the tire's equator, so that the cord is spirally wound in the tire running direction. A manufacturing method has been proposed in which a band layer is formed without a joint portion appearing in a direction that intersects with the band layer.

[0007]

[Problems to be Solved by the Invention] However, in the proposed method, the band cord l is continuous from one end p1 of the band layer m to the other end p2 as shown in FIG. It takes time to attach the cord, and if a defective point is found, such as slack at the start end or intermediate position of the winding, the cord must be rewound to the defective point and then re-wound, which reduces workability. There is a problem with being inferior.

[0008] According to the present invention, the band layer is formed by a plurality of band ply pieces divided in the tire axial direction, and each of the band ply pieces spirally winds a long belt-like ply in the same direction. This is a basic manufacturing method, and the purpose is to provide a method for manufacturing a band layer that can improve productivity and improve the handling stability of motorcycle tires manufactured according to the present invention when running at high speeds.

[0009]

[Means for Solving the Problems] The present invention includes a carcass that passes from a tread portion through a sidewall portion and folds around a bead core of a bead portion, and a band layer disposed inside the tread portion and outside the carcass in the radial direction. A method for manufacturing the band layer of a motorcycle tire having the following, wherein the band layer is formed of a plurality of band ply pieces divided in the tire axial direction, and each band ply piece has a band cord topped with rubber. This is a method for manufacturing a band layer in which a long band-shaped ply embedded in a tire is formed by spirally winding the ply at a small angle with respect to the tire equator and tilting in the same direction.

0010

[Operation] Since the band layer is formed by winding a narrow band ply with a band ply piece embedded in the topping rubber, the motorcycle tire manufactured by this manufacturing method has the following characteristics as shown in Fig. 7 (A). Unlike the conventional belt layer shown in Figure 1, there is no seam in the direction that is inclined to the tire equator, and it is possible to improve the stability of steering when going straight and turning.

In addition, the band layer is formed by a plurality of band ply pieces divided in the axial direction of the tire, and each ply piece has a band-shaped ply wound spirally in the same direction. The productivity of the band layer is improved because the winding can be applied at the same time.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIGS. 1 to 4, a motorcycle tire 1 formed using the manufacturing method of the present invention includes a tread portion 2, a sidewall portion 3 extending inward in the tire radial direction from both ends of the tread portion 2, and the sidewall portion. The motorcycle tire 1 has a bead core 4 which extends from the tread part 2 through the sidewall part 3 to the bead part 4. 5
The carcass 6 is provided with a winding part 6b that winds up the tire from the inside in the axial direction to the outside, and the band layer 7 is disposed inside the tread part 2 and adjacent to the outside in the radial direction of the carcass 6. A bead apex 9 having a triangular cross section is erected on the outside of the tire in the radial direction and between the winding portion 6b and the main body portion 6a.

[0013] The carcass 6 is composed of one or more carcass plies, in this embodiment, one carcass ply, which has a carcass cord inclined at an angle of 70 to 90 degrees with respect to the tire equator C. The cord used is an organic fiber cord such as nylon, rayon, polyester, or aromatic polyamide.

The band layer 7 according to the present invention is formed by a plurality of band ply pieces divided in the axial direction of the tire. In this embodiment, the band ply piece 7a and 7b are made up of two band ply pieces 7a and 7b whose dividing point is on the tire equator C.

Each band ply piece 7a, 7b is formed by spirally winding a long band-shaped ply 10.

As shown in FIG. 3, the band-shaped ply 10 is made up of one or a plurality of band cords 11 arranged in parallel, in this embodiment one band cord 11, embedded in the topping rubber 12, and the band cord 11 has a modulus of elasticity. It is preferable to use an organic fiber cord such as Teflon, aromatic polyamide, polyester, etc. and a steel cord having a high elastic modulus of 600 kgf/mm2 or more.

[0017] If the elastic modulus is less than 600 kgf/mm2, the rigidity of the tread portion 2 will be insufficient, resulting in reduced high-speed straight running performance, high-speed turning performance, and poor durability.

[0018] Aromatic polyamide fibers can be suitably employed because they have a high tensile strength almost equivalent to that of steel, are highly flexible, and have a lower specific gravity than steel, thereby reducing the weight of the tire.

The two band ply pieces 7a, 7b tilt the band ply 10 at a small angle of 10 degrees or less, preferably 5 degrees or less with respect to the tire equator C, and the band ply pieces 7a, 7b are oriented in the same direction. It is formed by a spiral winding that is inclined to

One band ply piece 7a starts from a point F1 located near one tread end E1 in FIG. 1, and moves toward the tire equator C as shown by the arrow in FIG. Strip ply 10 as end point
It is formed by spirally winding.

The other band ply piece 7b is formed by spirally winding the band ply 10 in a direction away from the tire equator C from a point G near the tire equator C and ending at a point F1 near the other tread end E2. formed by.

In this way, one band ply piece 7 and the other band ply piece 7
Since both a and 7b are spirally wound with leads tilting in the same direction, one band ply piece 7a and the other band ply piece 7b can be wound simultaneously, so that the band layer 7 can be formed in a short time. Furthermore, since the leads are in the same direction, a device for spiral winding can be easily manufactured and the winding accuracy can be easily improved.

Note that the developed width Wb of the band layer 7, that is, the surface length between the band layer edges F1 and F2 in the axial direction of the tire is 0.7 of the tread surface length Wt between the edges E1 and E2 of the tread portion 2.
It is preferable to form it so that it is larger than 1.0 times and smaller than 1.0 times. When the ratio is less than 0.7 times, the stiffness in the shoulder area of the tread decreases, resulting in a decrease in steering stability when making sharp turns, while when it is more than 1.0 times, the rigidity of the sidewall portion becomes excessive, resulting in poor ride quality. may decrease.

Furthermore, the band layer 7 may be divided into three or more band ply pieces, for example, four band ply pieces 7c, 7d, 7e, and 7f as shown in FIG. Furthermore, by making the unfolded widths (Wp...) of each band ply piece 7c, 7d, 7e, 7f approximately equal in the tire axial direction, the working time for spiral winding of each band ply 10... can be equalized, and the band layer 7
The molding time can be shortened.

[0025] The band layer according to the manufacturing method of the present invention is
In addition to being disposed adjacent to the radially outer side of the carcass as described above, a belt layer is provided on the outer side of the carcass and is placed radially outwardly of the belt layer and adjacent to the belt layer, so that the belt layer is tightened by the band layer. May be placed.

[0026]

[Specific Example] When manufacturing a band layer adopted for a tire with a tire size of 170/60 R17, the manufacturing method according to the present invention was used (Examples 1 and 2), and the conventional manufacturing method was used (comparison). The molding time was compared with Examples 1 and 2).

Further, each of the band layers of Examples and Comparative Examples was incorporated into a tire of the above-mentioned size, and a test was conducted to compare tire performance. The test conditions are as follows:

1) Molding time The total time required for molding including preparation time was measured and Comparative Example 1
It is expressed as an index of 00. The smaller the value, the less time required for molding.

2) High-speed straight running stability, high-speed turning stability A prototype tire was installed on a motorcycle, and the motorcycle was driven on a straight road at 260 km/Hr on a test road.
Each vehicle was driven at a speed of 220 km/hr on a curved road with a radius of curvature of 400 m, and was evaluated based on the feeling of the test driver, and expressed as an index with the specific example being 100. The larger the value, the better.

3) Using a high-speed durability drum tester, apply the internal pressure and maximum load specified in the JIS standard to the sample tire, and use a step speed method in which the initial speed is increased by 10 km/H every 20 minutes from an initial speed of 160 km/H. A high-speed durability test was conducted. Judgment was made based on the speed at which cracks appeared in the tread, and expressed as an index with Comparative Example 1 being 100. The larger the number, the better.

[0031]

[Table 1]

As a result of the test, it was found that the molding time of the example was significantly shorter than that of the comparative example, and the straight running stability and turning stability at high speeds were also excellent.

[0033]

As described above, the manufacturing method of the present invention is such that the band layer disposed on the outside of the carcass of the tread portion is formed by a plurality of band ply pieces divided in the axial direction of the tire, and each band ply piece is is formed by spirally winding band-shaped plies with embedded band cords tilted in the same direction, making it possible to increase productivity, reduce costs, and improve running stability during high-speed running.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a motorcycle tire manufactured using the manufacturing method of the present invention.

FIG. 2 is a developed plan view showing the arrangement of the carcass and band layers.

FIG. 3 is a perspective view showing an example of a belt-like ply.

FIG. 4 is a cross-sectional view showing winding of a band-shaped ply.

FIG. 5 is a sectional view showing another example of winding of the belt-shaped ply.

FIG. 6 is a sectional view showing a prior art.

FIG. 7A and FIG. 7B are both plan views showing a conventional technique.

[Explanation of symbols]

2 Tread portion 3 Sidewall portion 4 Bead portion 5 Bead core 6 Carcass 7 Band layer 7a, 7b, 7c, 7d, 7e, 7f Band ply piece 10 Band ply 11 Band cord 12 Topping rubber C Tire equator

Claims (1)

[Claims] [Claim 1] A motorcycle tire having a carcass that passes from a tread part through a sidewall part and folds around a bead core of a bead part, and a band layer disposed inside the tread part and outside the carcass in the radial direction. A method for manufacturing a band layer, wherein the band layer is formed by a plurality of band ply pieces divided in the axial direction of the tire, and
A method for producing a band layer in which each band ply piece is formed by spirally winding a long band-shaped ply in which a band cord is embedded in topping rubber and tilts in the same direction at a small angle with respect to the tire equator.