JPS60147326A - Manufacture of tire - Google Patents

Abstract

PURPOSE:To improve the drainage, irregular wear resistance and durability in a tire in which zigzag or block pattern is formed in combination with lateral and longitudinal grooves by providing a plurality of cutouts over the entire width of the surface of the tread. CONSTITUTION:A tire 1 is cut with cutting grooves 9 by a cutter after crude cover tire is molded and vulcanized. In other words, the grooves 9 are set to be inclined in parallel with an oblique angle beta' of lateral grooves 10 in a range of 50-80 deg. preferably to the equator of the tire substantially rectilinearly over the entire width of the tread 2 without having substantially groove width across the raised portions between the main grooves 4, 4 of the tread 2 by a cutter such as knife or cutting tool having relatively reduced thickness smaller than 3mm. or less of the acute thickness. Further, the depth (d) of the grooves 9 is in a range of 35-110% of the depth D of the groove 4, an interval L is in a range of 5-50mm., and preferably 10-30mm..

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a tire that forms a rib-lug pattern or a block pattern by a combination of horizontal grooves and vertical grooves, and improves drainage performance and durability by providing a plurality of incisions along almost the entire length of the tread surface. The present invention relates to a method for manufacturing tires that can improve uneven wear resistance, durability, etc.

In general, in order to improve the braking force, turning performance, and maintenance of snow performance of tires on wet or snowy roads, it is necessary to effectively eliminate water and snow interposed between the tread surface and the road surface. Therefore, as a trend pattern, a block type or a replug type is mainly adopted, and moreover, it has a zigzag-like leading groove width and groove depth extending in the circumferential direction, and a wide lateral groove extending to the tread edge. This improves drainage and snow performance.

On the other hand, in such tires, especially steel laminated tires for heavy vehicles, due to the heavy load and ground pressure distribution of the tread, so-called railway wear occurs along the convex portions on both edges sandwiching the main groove. There are problems such as wear, so-called heel-and-toe wear in which uneven wear occurs at the front and rear of the block in the running direction, and so-called shoulder-drop wear in which part of the tread shoulder wears faster than the center of the tread. For example, railway wear can be reduced by providing thin sipes at regular intervals along both edges of the main groove, and shoulder drop wear can be reduced by providing a large number of thin sipes at both ends of the tread. However, conventionally, such siping was formed by protruding a thin plate into the mold and forming it at the same time as vulcanization, so it was difficult to reduce the groove width from the perspective of preventing deformation of the blade. As a result, there has been a problem in that the rigidity of the tread portion is reduced, which may actually reduce wear resistance or adversely affect drainage performance.

As a tire manufacturing method that can solve these problems, after molding a raw cover tire and vulcanizing it, the tread surface of the tire is vulcanized at 30 to 30 degrees with respect to the equator of the tire.
A method of providing a plurality of cuts inclined at an angle of 90° at intervals of 5 to 50 m in the circumferential direction of a tire has already been disclosed and implemented.

However, when making cuts using this method, in patterns that have horizontal grooves such as the block pattern shown in Figure 1 or the rib-lug pattern shown in Figure 2, due to the relationship between the horizontal groove angle and the cut angle, the cut is surrounded by the groove and the cut. Small triangular parts may remain on the tread surface. Since the rigidity of this minute part is significantly different from that of other areas, it can cause uneven wear, and this part can be damaged while the tire is running and chipped or torn off, causing the tire's appearance to change. This may lead to a decrease in durability.

The purpose of this invention is to provide a method for manufacturing tires having a block type or replug type pattern with excellent uneven wear resistance and abrasion resistance. In a tire that is vulcanized to form a rib-lug pattern or a block pattern on the tread surface by a combination of horizontal grooves and vertical grooves, 1. The tire is characterized in that a plurality of cuts are provided in the tire circumferential direction substantially parallel to the lateral grooves on the tread surface and inclined in an angle range of 30 to 90 degrees with respect to the tire equator.

An embodiment of the present invention will be described below based on the drawings.

First, an example of a tire obtained by the tire manufacturing method of the present invention will be described.
In the figure, a tire 1 has a tread surface 3 with a zigzag main groove 4 continuous in the circumferential direction at the center and both sides, and the tread portion 2 is connected to a tread center portion 5 and a pair of left and right treads. The shoulder part is divided into 6, and the inside is 80° to 90° with respect to the equator C of the tire.
A carcass 7 consisting of cords arranged at an angle of
A belt layer 8 made of a steel cord is arranged under the tread part 2, while a cut 9 is provided which is inclined with respect to the equator C of the tire over the span of the tread part 2.
A large number of incisions 9 are provided in the circumferential direction, and the tire 1 is manufactured by forming and vulcanizing a green cover tire and then forming the incisions 9 therein. The raw cover tire has a toroidal shape in which a carcass 7, a belt layer 8, a bead part (concave, no groove), and a tread part 2 are combined on a molding drum, and this is placed in a mold by a usual method. After vulcanization, the original tire is taken out from the mold and a cut 9 is made with a knife. Here, the cut 9 crosses the ridge between the main grooves 4 and 4 of the tread portion 2, which is carved by a sharp and relatively thin knife, bit, grindstone, or saw blade with a thickness of about 3 mm or less. It is a cut, which can be formed without substantially having a groove width, and is provided at an angle of inclination β with respect to the equator C of the tire over the entire width of the tire l as described above, and this β is divided by the lateral grooves 10 on both sides of the tread. The edge 15 of the block 14 is arranged parallel to the angle β' with respect to the tire equator C.

The lateral grooves of conventional tires, which are formed at the same time as vulcanization in a mold equipped with blades, have a relatively wide sipe size that cannot be formed into small sipes even in principle, but according to the present invention. In the tire 1, since the groove width of the notch 9 can be made small enough to be practically ignored, both edges of the notch 9 are strongly pressed against each other due to the compressive stress acting within the ground contact surface. It functions as if it were a continuous, integrated rubber layer, and by improving rigidity, it can prevent a decrease in wear resistance. In addition, in response to bending stress that occurs near the ground contact edge, the notches 9 can be flexibly deformed, making it possible to effectively disperse and relieve the stress.This not only prevents shoulder drop wear of the tread portion 2, but also reduces bounce during running. The grip is improved when stepping out and stepping in. In addition, the notch 9 that is opened during bending deformation
Both edges cut the water film and improve drainage in the 4 directions of the main groove. In order to enhance this effect, the cut 9 is made in a substantially straight line throughout the tread portion 2, and also in the equator C of the tire.
at an angle of 30° to 90°, preferably 50° to 8
It is set so that it is inclined parallel to the inclination angle β' of the lateral groove 10 within a range of 0°. If the inclination angle of the notches 9 is too small, the effect of preventing uneven wear will be reduced and the effect of improving wet grip properties will be reduced. Further, the depth d of the notches 9 is in the range of 35 to 110% of the groove depth D of the main groove 4, and the interval between the notches 9 is 5 to 50, preferably 1
The range is 0 to 30 cranes. If an excessively large number of notches 9 are provided, the rigidity of the tread 2 will be reduced, resulting in impaired steering stability and wear resistance. Note that the cuts 9 can be arranged at irregular intervals in addition to regular intervals in the circumferential direction.
Furthermore, it can be formed so that several types of intervals are periodically repeated. Another method is to alternately change the depth d on both sides of the tread to prevent damage to the rubber due to cuts. Note that the cut 9 is made by normal machining from the viewpoint of productivity and processing accuracy, and furthermore, by using an automatic cutting machine that can adjust the cut position and angle.

As described above, in the tire manufacturing method of the present invention, incisions are made parallel to the slope of the lateral groove after the tire is vulcanized, so that minute portions are not formed and the incisions can be formed to have a small width with virtually no groove width. This improves wet grip, uneven wear resistance, drainage, etc. In addition, there is no need to perform complicated processing such as installing blades to form horizontal grooves on the mold, which reduces mold costs and allows users to change the shape and dimensions of the cut to suit their needs. There are advantages.

The manufacturing method of the present invention can be applied to various rib-lug type and pro-rough type tires such as passenger car tires and molded vehicle tires.

The 1000R20 steel radial tires shown in Figures 3 and 4 were cut according to the specifications shown in Table 1, and the characteristics such as abrasion resistance and wet grip were evaluated. Table 1 shows the results. It is clear that the tire manufactured by the tire manufacturing method of the present invention has improved mechanical properties.

Note 1) As shown in Figure 1. However, no incisions are made Note 2) Measured using a trailer tester under wet conditions on JARI's general test track, and is expressed as a relative value to the comparative example. The higher the value, the better.

Note 3) The distance traveled until the tread wears out in actual vehicle driving tests is expressed as a relative value.

Note 4) Measured using a transfer resistance tester.

[Brief explanation of drawings]

1 and 2 are partial plan views illustrating tires obtained by the conventional manufacturing method, FIG. 3 is partial plan views illustrating tires obtained by the manufacturing method of the present invention, and FIG. 4 is a partial plan view illustrating tires obtained by the manufacturing method of the present invention. The AA sectional view and FIG. 5 are partial plan views showing another embodiment obtained by the present invention. 1--Tire, 2--Tread section, 3-) Red surface, 4--Main groove, 9-Notch, 10-Horizontal groove, C--Tire equator. Patent applicant Sumitomo Rubber Industries Co., Ltd. Agent Patent attorney Tadashi Naemura

Claims (1)

[Scope of Claims] - (11) A tire in which a raw cover tire is formed and then vulcanized to form ribs - a lug pattern or a block pattern - on the tread surface by a combination of horizontal grooves and vertical grooves. A method for manufacturing a tire, characterized in that a plurality of cuts are provided in the tire-to-tire direction at angles that are substantially parallel to the lateral grooves and inclined at an angle range of 30 to 90 degrees with respect to the tire equator. It has substantially no width on the surface, and the depth is 35 to 35% of the depth of the tire main groove.
110% and the same depth throughout the tread,
The method for manufacturing a tire according to claim 1, wherein the depth is alternately changed. (3) The method for manufacturing a tire according to Claims 1 and GS2, wherein the depth of the cut is different on both sides of the tire. (4) The method for manufacturing a tire according to claims 1, 2, and 3, wherein the number of cuts is an integral multiple of the number of pinches.