JP2005041328A - Pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire capable of enhancing the tire uniformity by suppressing the varying width of RFV resulting from reinforcement layers formed by winding a strip material spirally. <P>SOLUTION: The pneumatic tire 1 is arranged so that the strip material 10X lined with rubber while a plurality of reinforcing cords are laid parallel in alignment, is wound spirally in turns in the tire circumferential direction so that reinforcement layers 10 and 10' are formed on the tire periphery and the side faces, wherein the cut ends 10Xa and 10Xb at the start and termination in winding of the strip material 10X are shaped acutely to the longitudinal direction of the strip material 10X. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a pneumatic tire, and more particularly, to a pneumatic tire that improves tire uniformity when a reinforcing material is formed by continuously spirally stripping a strip material.

In the case of a pneumatic radial tire, in order to suppress the rising phenomenon due to the centrifugal force of the belt layer during high speed running and to improve the high speed durability, a large number of reinforcing cords on the outer periphery of the belt layer are approximately 0 ° in the tire circumferential direction. Arrangement of belt reinforcing layers arranged at an angle is performed. Conventionally, FIG.
As shown in FIG. 4, in order to form such a belt reinforcing layer 10 on the molding drum 20 at the time of tire molding, a strip material in which a plurality of reinforcing cords are drawn in parallel at both ends of the belt layer 8 and rubberized. 10X is spirally wound, and the winding start end portion 10Xa and winding end end portion 10Xb of the strip material 10X are cut so as to be perpendicular to the longitudinal direction of the strip material 10X (see, for example, Patent Document 1). .).

However, in this structure, since a difference in rigidity is generated at the end portions 10Xa and 10Xb of the strip material 10X, the variation range of the radial force variation (hereinafter simply referred to as RFV) when the tire rotates due to the difference in rigidity. There is a problem of increasing tire uniformity.
Japanese Patent Laid-Open No. 10-193917

An object of the present invention is to provide an RFV resulting from a reinforcing layer formed by spirally winding a strip material.
It is an object of the present invention to provide a pneumatic tire that suppresses the fluctuation range of the tire and improves the tire uniformity.

In order to achieve the above object, a pneumatic tire according to the present invention is a tire outer periphery or side surface in which a plurality of reinforcing cords are stretched in parallel and rubberized strip material is spirally wound around the tire circumferential direction a plurality of times. In the pneumatic tire in which a reinforcing layer is formed, the cut ends of the strip material at the start and end of winding are formed at acute angles with respect to the longitudinal direction of the strip material.

The acute angle formed by the winding start end and the winding end end of the strip material with respect to the longitudinal direction of the strip material is preferably 10 ° to 55 °. Further, it is preferable that the winding start end portion and the winding end end portion of the strip material overlap each other in the tire circumferential direction. Further, in this case, the position of the winding start end portion and the winding end end portion are The distance separating in the tire circumferential direction is preferably 5 mm to 300 mm.

According to the pneumatic tire of the present invention, when the reinforcing layer is formed by spirally winding the strip material, the winding start end portion and the winding end end portion are acutely angled with respect to the longitudinal direction of the strip material. It is possible to mitigate the change in rigidity of the layer with respect to the tire circumferential direction so that the tire uniformity can be improved.

Further, when the winding start end portion and the winding end end portion of the strip material overlap each other in the tire circumferential direction, the rigidity in the tire circumferential direction can be made more uniform.

Hereinafter, the pneumatic tire of the present invention will be described with reference to the embodiments shown in the drawings.

FIG. 4 shows the case of a pneumatic radial tire. The pneumatic radial tire 1 includes a tread 2, a side portion 3, and a bead portion 4, and a carcass layer 5 is provided on the inner side. Carcass layer 5
Has carcass cords (reinforcing cords) arranged at approximately 90 ° with respect to the tire circumferential direction, extending from the tread 2 to the left and right side portions 3, and both ends around the left and right bead cores 6 from the inside to the outside of the tire It is configured to be folded back.

Two belt layers 7 and 8 are disposed on the outer circumferential surface of the tread 2 of the carcass layer 5, and belt reinforcing layers 10 are disposed at both ends on the outer circumferential side. Belt reinforcement layer 1
0 is substantially 0 in the tire circumferential direction so that the strip material 10X in which reinforcing cords such as a plurality of organic fiber cords are aligned in parallel and embedded in rubber is spiral and both side edges are in contact with each other.
It is configured by winding around an angle of °. The width of the strip material 10X is 5 to 20 mm, preferably 15 to 20 mm.

In the present invention, the belt reinforcing layer 10 is formed as shown in FIGS. 1 and 2 at the time of tire molding.

After the belt layers 7 and 8 are wound on the forming drum 20 configured to be expandable and contractable in the radial direction, the strip material 10X is spirally formed on both ends of the belt layer 8 on the outer layer side from the drum center side to the outside. Wrap around. The angles α and β between the winding start end portion 10Xa and the winding end end portion 10Xb of the strip material 10X wound in this way with respect to the strip material longitudinal direction are both cut at an acute angle. Further, in the strip material 10X wound in a spiral shape, the side edges adjacent to each other are preferably butt-joined, but may be partially overlapped or may be interposed with a gap. The strip material 10X wound in this way has a cord angle with respect to the tire circumferential direction of substantially 0 °, thereby enhancing the tagging effect on the belt layers 7 and 8,
Suppresses the phenomenon of rising due to centrifugal force and improves tire durability.

Further, since both the winding start end portion 10Xa and the winding end end portion 10Xb of the strip material 10X are acute angles with respect to the longitudinal direction, there is no step in the change in rigidity of the belt reinforcing layer 10 in the tire circumferential direction, and RFV Since the fluctuation range is reduced, the tire uniformity can be improved.

The angles α and β with respect to the longitudinal direction of the winding start end portion 10Xa and the winding end end portion 10Xb exhibiting such effects are preferably 10 ° to 55 °. The angles α and β are usually preferably the same angle, but may be different from each other.

Further, the winding start end portion 10Xa and the winding end end portion 10Xb of the strip material 10X are arranged in a positional relationship overlapping each other in the tire circumferential direction. More preferably, the separation distance R in the tire circumferential direction between the tips of the winding start end portion 10Xa and the winding end end portion 10Xb is 5 mm to 3 mm.
It is preferable to set it to 00 mm.

In FIG. 1 and FIG. 2, the number of windings of the strip material 10X is shown as a schematic diagram of four times. However, in actuality, the number of times of the strip material 10X is five times or more depending on the width required for the belt reinforcing layer. Of course.

FIG. 3 shows another embodiment of the present invention. In this embodiment, the strip material 10 </ b> X is spirally wound as a side reinforcing layer 10 ′ that reinforces the side portion 3. The side reinforcing layer 10 'is formed by winding the carcass layer 5 on a forming drum and then winding the strip material 10X in a spiral manner in the region corresponding to the side portion 3 of the carcass layer 5 in the same manner as described above. The

When manufacturing a pneumatic radial tire having the tire structure shown in FIG. 4 with a tire size of 225 / 60R16, a strip material having a width of 20 mm in which ten nylon cords are aligned and rubberized is used as a strip material constituting the belt reinforcing layer. As shown in Table 1, the conventional example in which the cutting angle at the winding start and winding end ends is 90 °, and 55 °, 45 °, and 20 °, respectively.
Five types of pneumatic tires of Examples 1, 2, 3, and 4 at 10 ° were manufactured.

When RVF was measured for these five types of tires under the following conditions, the results shown in Table 1 were obtained. The RFV test conditions were measured according to JASO C607 and evaluated by the reciprocal of the maximum fluctuation range. The evaluation is expressed as an index with the tire value of the conventional example being set to 100, and the higher the index value, the better the uniformity.

表１の結果から、実施例１から実施例４は従来例に比べてＲＶＦが向上しており、タイ
ヤのユニフォミティが向上していることが分かる。

From the results in Table 1, it can be seen that Examples 1 to 4 have improved RVF and improved tire uniformity compared to the conventional example.

It is explanatory drawing which shows typically the state which wound the belt reinforcement layer of the pneumatic tire of embodiment of this invention on the forming drum at the formation process. It is the elements on larger scale which show the front-end | tip part and rear-end part of the reinforcement layer of FIG. It is a perspective view which shows the pneumatic tire applied to the side reinforcement layer which is other embodiment of this invention in the state except the sidewall rubber layer. It is a figure which shows the example of a meridian direction sectional drawing of a pneumatic radial tire. It is explanatory drawing which shows typically the state which wound the belt reinforcement layer of the pneumatic tire of the prior art on the forming drum at the formation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pneumatic radial tire 7,8 Belt layer 10 Belt reinforcement layer 10 'Side reinforcement layer 10X Strip material 10Xa Winding end part 10Xb Winding end part α Cutting angle of winding start end part Cutting angle of winding end part R circumference Directional distance

Claims (6)

In a pneumatic tire in which a plurality of reinforcing cords are stretched in parallel and rubberized strip material is spirally wound in the tire circumferential direction a plurality of times to form a reinforcing layer on the outer periphery or side surface of the tire. A pneumatic tire in which cut ends at the beginning and end of winding are formed at acute angles with respect to the longitudinal direction of the strip material. The pneumatic tire according to claim 1, wherein the angle of the cut end is 10 ° to 55 ° with respect to the longitudinal direction of the strip material. 3. The pneumatic tire according to claim 1, wherein the winding start cut end and the winding end cut end are arranged in a positional relationship overlapping each other in the tire circumferential direction. The distance at which the cut end at the start of winding and the cut end at the end of winding are separated in the tire circumferential direction is 5 mm.
The pneumatic tire according to claim 3, wherein the pneumatic tire is ˜300 mm. The pneumatic tire according to any one of claims 1 to 4, wherein the reinforcing layer is a belt reinforcing layer disposed on an outer periphery or an inner periphery of the belt layer. The pneumatic tire according to any one of claims 1 to 4, wherein the reinforcing layer is a side reinforcing layer arranged annularly on a sidewall.

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