JPS60252005A - Pneumatic tire - Google Patents

Abstract

PURPOSE:To improve braking property and driving property without sacrificing resistance to abrasion by applying, on the surface of a tire tread, siping with a sectional view varied in the direction of depth. CONSTITUTION:Siping SA, sectional view of which is varied in the direction of depth, is provided on the surface of a pneumatic tire. The siping SA forms corved parts B1, B2 at two points in the direction of depth, while width m1, m2 of respective curves of said parts are set within the limits of 1.0-6.0mm.. Further, an area SA1 adjacent to the surface of the tread and a bottom area SA2 of siping SA are formed nearly perpendicular to a tread GT. This further improves movability of a tread rubber and an improve braking property and driving property with less number of siping SA, while it does not cause sacrificing of resistance to abrasion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the shape of siping applied to a tire trend surface.

Spice tires are generally used for driving on snowy or icy roads in winter, but when driving on regular paved roads, spiked tires pose problems such as dust pollution and damage to the paved road.

Therefore, research and development of spikeless tires has been urgently needed, and it is important to improve braking performance and on-snow performance to the same extent as spiked tires. The tread surface is usually provided with siping S in the tire width direction along the tread main groove G. This siping is generally formed with a width equal to or less than IN and a depth equal to or less than the tread main groove, and it improves braking performance and driving performance by giving the tread rubber flexibility so that it can sufficiently follow deformation during ground contact. One of the purposes is to improve sexual performance. As shown in the cross-sectional view of FIG. 2, the conventional siping is formed at an angle that is substantially perpendicular to or close to the tire contact surface GT, and has a substantially linear cross section. Braking performance tends to improve by increasing the number of sipings on the tread surface, the depth, width, or length of sipings, but on the other hand, it also reduces wear resistance, so conventional methods It was designed with balance in mind.

In addition, according to the inventor's knowledge, the sipe also deforms as shown by the dotted line in FIG. 2 during repeated deformation due to tire rotation, but the larger the step due to rubber deformation on both edges E1 and B2 of the sipe, the better the braking performance. There is a tendency to Therefore, the present invention has investigated the relationship between the cross-sectional shape of the siping and the deformation behavior of the tread, and by making the cross-sectional shape of the siping curved, braking performance and driving performance can be improved without sacrificing wear resistance. This enabled further improvement, leading to the present invention. That is, the present invention is a pneumatic tire characterized by having siping attached to the tire tread surface and having a cross-sectional shape curved in the depth direction. An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows a sectional view of the siping of the pneumatic tire of the present invention. Here, the siping SA is applied to the tread surface in the same way as conventional siping, and FIG. 3 corresponds to the AA sectional view in FIG. 1. In FIG. 3, the siping SA has two bending portions B1 and B2 in the depth direction, and the bending widths m1 and m2 are both in the range of 1.0 to 6.0 period. If the bending widths m1 and m2 are smaller than 1.0,
Not being able to impart sufficient flexibility to the tread rubber, on the other hand, 5mm
Exceeding this will cause undue deformation and strain, which will result in rubber cracks and will generally make it difficult to form siping. Note that at least one inflection part is required for one sipe, and two or more inflection parts can also be formed. In addition, it is preferable that the siping SAI and the siping bottom SA2 be formed almost perpendicular to the ground contact surface GT, which is close to the tread surface of the siping. Ground plane GT
In this case, both edges of the tread rubber are formed in the same direction as the deformation strain to maintain sufficient strength against wear and damage.

In addition, in the present invention, the siping is attached to both ends of the trend part of a radial tire for heavy vehicles or along the longitudinal groove in the circumferential direction of the tire, similar to conventional siping, and can be used for the purpose of preventing uneven wear. It can be applied to various tires and retreaded tire treads, such as rib block patterns and rib lug patterns.The depth of the siping is the same as or less than the depth of the main groove, and the width is 2.
It is usually formed with a diameter of less than mm.

Furthermore, in order to form the siping on the tire trend surface, a method can be adopted in which a cutting member of a knife blade having a curved part is attached to the surface of the vulcanized metal and the siping is formed simultaneously with vulcanization. The formation method is exactly the same.

As mentioned above, in the present invention, the cross-sectional shape of the siping is shaped to have an inflection part, so compared to the conventional straight siping,
Braking performance and drive performance can be improved with fewer sipings by further increasing the mobility of the trail/de rubber, without sacrificing wear resistance. Furthermore, the siping according to the present invention has the advantage that, compared to straight siping, the difference in level due to rubber deformation at both edges of the sipe when it touches the ground is larger, resulting in higher braking performance and driving performance.

[Brief explanation of the drawing]

Figure 1 is a partial front view of the tire tread, and Figure 2 is a partial front view of the tire tread.
The AA sectional view in the figure and FIG. 3 are sectional views of the siping in the present invention. G...Vertical groove, S, SA・-siping, El, B2
- edge, G T - ground plane, B1, B2 - inflection. Patent applicant: Sumitomo Rubber Industries, Ltd. Representative patent attorney: Tadashi Naemura

Claims (3)

[Claims] (1) A tire characterized by having siping applied to the tire trend surface and having a cross-sectional shape curved in the depth direction. (2) The pneumatic tire according to claim 1, wherein the bending width (m) of the siping is in the range of 1.0 to 6.0 m. (3) The pneumatic tire according to claim 1, wherein the region close to the trend surface of the siping is substantially perpendicular to the ground contact surface.