JPS59169836A - Manufacture of tire - Google Patents

Abstract

PURPOSE:To improve wet gripping performance, wear resistance and draining performance, by providing a plurality of splits tilting to the equator of a tire extending over about a whole width of a tread surface of the tire after vulcanization of a green cover tire. CONSTITUTION:A green cover tire which is made into a toroidal state by combining a carcass 7, a belt layer 8, a bead part and a tread part 2 on a molding drum is arranged in a metal die by a conventional method for vulcanization. Then a slit 9 is processed on an original tire taken out of the metal die by a cutter. The slit 9 can be formed without having groove width substantially by a notch crossing a protruded part between main grooves 4, 4 of a tread part 2 provided by making use of cutters such as a comparatively thin knife and bit. Then the slit 9 is provided on a tire in a tilting state to the equator C of the tire 1 extended over a whole width of the tire 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tire that can improve drainage performance and durability by providing a plurality of incisions over almost the entire tread surface after vulcanization.

Generally, in order to improve the braking force and turning performance of a tire on a wet road surface, it is necessary to effectively eliminate water interposed between the tread surface and the road surface. Therefore, a lip type or lug type tread pattern is mainly adopted as a tread pattern, and the zigzag-shaped main groove extending in the circumferential direction has a large groove width and groove depth, and wide lateral grooves extending from the main groove to the tread end. By providing this, drainage performance is 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 railway wear occurs along the convex portions on both edges sandwiching the main groove. There are problems such as so-called heel-and-toe wear, in which uneven wear occurs at the rear end of the block in the running direction, or so-called shoulder-drop wear, in which a portion of the tread shield wears more rapidly than the center of the tread. For example, railway wear can be reduced by providing thin lateral grooves at regular intervals along the edge of the main groove, and shoulder drop wear can be reduced by providing a large number of thin lateral grooves at both ends of the tread. However, such lateral grooves have conventionally been formed at the same time as vulcanization by installing a thin plate in advance in the mold, so it is difficult to reduce the width of the grooves 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.

The purpose of the present invention is to provide a tire manufacturing method capable of solving such problems, and after molding and vulcanizing a green cover tire, almost the entire tread surface of the tire is vulcanized with respect to the equator of the tire. It is characterized by providing a plurality of notches that are slanted.

An embodiment of the present invention will be described below with reference to the drawings.

First, an example of a tire obtained by the tire manufacturing method of the present invention will be described. FIG. 1 shows an expanded view of the right half of the tread portion 2 of the tire 1, and FIG. 2 shows an A-A cross section thereof. , the tire 1 has its tread surface 3
A zigzag-shaped main groove 4 continuous in the circumferential direction is provided in the center and both sides, dividing the tread portion 2 into a tread center portion 5 and a pair of left and right tread shoulder portions 6, Inside is 80 to the tire's equator C.
A carcass 7 made of cords arranged at an angle of ~90 degrees, and a belt layer 8 made of steel cords on which the tread part 2 is arranged, A large number of incisions 9 are provided in the circumferential direction, and the tire 1 is manufactured by forming and vulcanizing a raw cover tire, and then forming the incisions 9. The green 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 molding drum, and this is placed in a mold by a conventional method. After vulcanization, cut into the original tire taken out from the mold with a knife 9
is processed. Here, the cut 9 is sharp and has a thickness of 3
The main groove 4 of the tread portion 2 is carved by a comparatively thin knife, bit, grindstone, saw blade, etc. that is less than fi.
．． This is a cut that crosses the ridges between the two grooves, and can be formed without substantially having a groove width, and is provided obliquely 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 groove size, which cannot be achieved in principle in small grooves, but according to the present invention. Tire 1
In this case, 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 the compressive stress acting within the ground plane, making it appear as if it were continuous. It functions as an integrated rubber layer, which improves rigidity and prevents deterioration of 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 alleviate the stress, thereby preventing the tread portion 20 from shoulder drop wear, etc. , the stepping, that is, the grip is improved. Furthermore, both edges of the notch 9 that are opened during bending deformation cut the water film and improve drainage in the direction of the main groove 4. In order to enhance this effect, the cut 9 is made in a substantially straight line throughout the entire tread portion 2, and at an angle of 30 mm with respect to the equator C of the tire.
It is preferable to set the inclination at an angle of 90° to 90°, preferably 50° to 80". If the inclination angle of the notch 9 is too small, the effect of preventing uneven wear will decrease and the wet grip property will be reduced. The improvement effect becomes small. Also, the depth d of the notch 9 is 50 to 1 of the groove depth D of the main groove 4.
The range is 10%, and the spacing of the notches 9 is 5 to 5.
0 m, preferably in the range of 10 to 30 fi. If an excessively large number of cuts 9 are provided, the rigidity of the tread 2 will be reduced, and the steering stability and wear resistance will be deteriorated. Note that the incisions can be arranged not only at regular intervals in the circumferential direction but also at irregular intervals, and furthermore, they can be formed so that several kinds of intervals are periodically repeated. Furthermore, several types of cuts with different groove depths d may be mixed. 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.

In this way, in the tire manufacturing method of the present invention, the incisions are made after the tire is vulcanized, so the incisions can be formed into small widths with virtually no groove width, resulting in improved wet grip, abrasion resistance, and even better performance. Drainage properties etc. are improved. 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 types of tires such as passenger car tires, molded vehicle tires, etc. Suitable for use in steel radial tires for trucks and buses, which have 2 to 5 main grooves.

The 1000R20 steel radial tires shown in Figures 1 and 2 were cut according to the specifications shown in Table 1, and properties 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 characteristics.

Note 1) As shown in Figure 1. Note 2) Measured with a trailer tester under wet conditions on JARI's comprehensive test track, and is shown as a relative value to the comparative example. The larger the value, the better.

Note 3) The distance traveled until the tread wears out by 1 inch in an actual vehicle driving test is shown as a relative value.

Note 4) Measured using a transfer resistance tester.

[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 FIG. 2 is a cross-sectional view taken along line AA. ■-tire, 2...-tread section, 3-) red surface, 4-main groove, 9-notch, C-tire equatorial patent applicant
Sumitomo Rubber Industries Co., Ltd. Representative Patent Attorney Masaru Naemura 168- (J%J

Claims (1)

[Claims] (1) After forming a green cover tire and vulcanizing it, a plurality of incisions that are inclined with respect to the equator of the tire are provided over almost the entire tread surface of the tire. How tires are manufactured. (2) The method for manufacturing a tire according to claim 1, wherein the cuts are substantially straight and are provided at equal intervals in the circumferential direction of the tire. (3) The cut is 30° to the equator of the tire.
2. The method of manufacturing a tire according to claim 1, wherein the tire is inclined at an angle of 90°. (41) The method for manufacturing a tire according to claim 1, characterized in that the incisions are provided at intervals of 5 to 50 squares in the circumferential direction of the tire. (5) The tread surface of the tire is , a method for manufacturing a tire according to claim 1, characterized in that the tire has 2 to 5 zigzag-shaped main grooves continuous in the circumferential direction. (6) The tire is for use in trucks and buses. A method for manufacturing a tire according to claim 1, which is a steel radial tire.