JPS6218305A - Manufacture or tire - Google Patents

Abstract

PURPOSE:To improve water expelling performance and abrasion resistance by making the depth of cut-in parts deeper than the depth of the lateral groove for forming a rib lug pattern, etc., in a tire which has the rib lug pattern, etc. on the tread surface and has a plurality of cut-in parts nearly over the whole width. CONSTITUTION:In a tire 1, the main grooves 4 which are continuous in zigzag form in the circumferential direction are formed at the center part and the both side parts on a tread surface 3, and a tread part 2 is divided into a tread center part 5 and a tread shoulder part 6, and these parts are manufactured by shaping and vulcanizing a raw rubber tire. After the shaping of the tread part 2, a number of cut-in parts 9 which incline with respect to the equator C of the tire are formed in the circumferential direction over the whole width of the tread part 2. In this case, the depth D2 of the cut-in part 9 is set to 105% or more of the depth D1 of the lateral groove 10 which forms a rib lug pattern or block pattern obtained through the extension in the direction crossing the main groove 4 and cooperation with the main grove 4, preferably within a range of 110-160%.

Description

Detailed Description of the Invention The present invention provides a tire in which a rib-lug pattern or a block pattern is formed by a combination of horizontal grooves and longitudinal grooves, and in which a plurality of cuts are provided over almost the entire width of the tread surface. The present invention relates to a method for manufacturing a tire that can improve drainage performance, uneven wear resistance, wear resistance, durability, etc. by cutting the grooves deeper than the depth of the lateral grooves.

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, the block type or rib-lug type tread pattern is mainly adopted, and moreover, the zigzag-shaped main grooves extending in the circumferential direction have large groove widths and groove depths, and wide lateral grooves extending to the tread ends. By providing this, drainage performance, drivability, and performance on snow are improved.

On the other hand, in such tires, especially steel radial tires for heavy vehicles, due to the heavy load and ground pressure distribution of the tread, so-called rails wear along the convex portions on both edges sandwiching the main groove. There are problems such as way wear, so-called heel-and-toe wear where uneven wear occurs at the front and rear of the block in the running direction, and so-called shoulder drop wear where part of the tread shoulder wears out more quickly 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 tread, and shoulder drop wear can be reduced by providing a large number of thin sipes at both ends of the tread. However, since such siping has traditionally been formed at the same time as vulcanization by installing a thin plate in advance in the mold, there is a limit to reducing the groove width from the perspective of preventing deformation of the blade. As a result, there is a problem in that the rigidity of the tread portion is reduced, which actually reduces the wear resistance or adversely affects the drainage performance.

As a tire manufacturing method that can solve these problems, after molding a green cover tire and vulcanizing it, a 30 to
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 practiced.

However, in the conventional cutting method, as shown in FIG. 2, the depth D2 of the cut 9 was cut shallower than the groove depth Dl of the lateral slO, so the block element B sandwiched between the cut 9 and the lateral groove 10 Due to repeated deformation of the tread contact surface,
Cracks occur in the tire circumferential direction from the bottom 5 of the cut,
The block element B is chipped or torn off while the tire is running, resulting in a decrease in the appearance and durability of the tire.

An object of the present invention is to provide a method for manufacturing a tire having a block type or replug type pattern that effectively eliminates such problems in conventional tires and has excellent uneven wear resistance and abrasion resistance. A raw cover tire is molded and then vulcanized to form a rib-lug pattern or a block pattern on the tread surface by a combination of horizontal grooves and vertical grooves. 30-9 to the tire equator at a parallel angle
A tire having a plurality of cuts in the tire circumferential direction that are inclined within an angle range of 0° is characterized in that the depth of the cuts is deeper than the depth of the lateral grooves.

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 zigzag main grooves 4 continuous in the circumferential direction at the center and both sides, and the tread portion 2 is connected to a trend center portion 5 and a pair of left and right treads. The shoulder part is divided into 6 and the inside is 80" to 9° with respect to the tire's equator C.
A carcass 7 consisting of cords arranged at an angle of
A belt layer 8 made of steel cord is provided under the tread portion 2, and cuts 9 are formed across the entire width of the tread portion 2 and are inclined with respect to the equator C of the tire.
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 (not shown) and a tread part 2 are combined on a formed f-ram,
After placing this in a mold and vulcanizing it by a usual method, the original tire taken out from the mold is cut 9 with a knife. Here, the cuts 9 are between the main grooves 4 and 4 and the lateral grooves 10 and 10 of the tread portion 2, which are cut using a sharp and relatively thin knife, bit, grindstone, saw blade, etc. with a thickness of about 3 fins or less. This cut crosses the ridge between the grooves, can be formed without substantially having a groove width, and is provided at an inclination angle β with respect to the equator C of the tire over the entire width of the tire 1 as described above.

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 width that cannot be formed in small tires in principle. In the tire 1, since the groove width of the notch 9 can be made so small that it can be practically ignored, both edges of the notch 9 are strongly pressed against each other due to compressive stress acting within the ground contact surface. It functions as if it were a continuous, integral 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 formed in a substantially straight line over the entire width of the tread portion 2, and is aligned with the tire's equator C.
The inclination angle β is set in the range of 30° to 90°, preferably in the range of 50′ to 80°. If the inclination angle β 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 D2 of the notch 9 is 105% or more of the groove depth Dl of the lateral groove 10, preferably 105% or more, as shown in FIG.
The spacing between the cuts 9 is in the range of 5 to 50 m, preferably 10 to 3 ON.

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 notches 9 can be arranged at irregular intervals in addition to regular intervals in the circumferential direction, and can also be formed so as to periodically repeat several kinds of intervals. A method is also adopted in which the depth Dl is alternately changed on both sides of the tread to prevent damage to the rubber due to cuts. From the viewpoint of productivity and processing accuracy, the incisions 9 are usually made by machine processing, and furthermore, by using an automatic incision machine that can adjust the incision 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 makes it possible to improve wet grip properties, uneven wear resistance, drainage properties, etc. In addition, there is no need to perform complex processing such as installing blades to form horizontal grooves on the mold (this reduces mold costs, and allows users to freely change the shape and dimensions of the cut to suit their needs). There are advantages that can be achieved.

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 heavy vehicle tires.

EXAMPLE A 10.0OR20 steel radial tire shown in FIG. 1 was cut according to the specifications shown in Table 1, and a vehicle 2-2.
Table 1 shows the results of evaluating the characteristics of chipping of the block elements by installing eight block elements in the tire D. It is clear that the characteristics of the tire manufactured by the tire manufacturing method of the present invention are improved.

[Brief explanation of the drawing]

Fig. 1 is a partial plan view illustrating a tire obtained by the manufacturing method of the present invention, and Figs. 2 and 3 are sectional views taken along line AA (however, Fig. 2 shows the conventional cutting depth). , FIG. 4 is a BB sectional view of the tire 1 obtained by the present invention. 1-tire, 2--tread section, 3--tread surface, 4--main groove, 9--notch, C--tire equator. Patent applicant Sumitomo Rubber Industries Co., Ltd. Agent
Patent attorney Tadashi Naemura @1m

Claims (4)

[Claims] (1) A green cover tire is formed and then vulcanized to form a rib-lug pattern or a block pattern on the tread surface by a combination of horizontal grooves and vertical grooves, which are almost parallel to the horizontal grooves over almost the entire width of the tread surface. A tire having a plurality of cuts in the circumferential direction of the tire that are inclined at an angle of 30 to 90 degrees with respect to the tire equator, characterized in that the depth of the cuts is deeper than the depth of the lateral groove. A method of manufacturing tires. (2) The cuts have substantially no width on the tire surface, have a depth of 105% or more of the depth of the lateral groove, and have the same depth or alternate depth over the entire width of the tread width. A method for manufacturing a tire according to claim 1, characterized in that the method varies. (3) The method for manufacturing a tire according to claims 1 and 2, wherein the depth of the cut is different on both sides of the tire width. (4) The method for manufacturing a tire according to claims 1, 2, and 3, wherein the pitch length of the cuts in the circumferential direction is comprised of one to three combinations. .