JPS60165231A - Manufacture of tire - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

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

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 rib 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 extend 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 rails wear along both edges and parts sandwiching the main groove. There are problems such as way wear, so-called heel-and-toe wear in which uneven wear occurs at the rear end of the block in the running direction, and so-called shoulder drop wear in which part of the tread shoulder wears out more than the center of the tread. For example, railway wear can be reduced by providing thin lateral grooves at regular intervals along both edges of the main groove, and shoulder drop wear can be reduced by providing many 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 method for manufacturing a tire that can solve such problems, and after molding and vulcanizing a green cover tire, the tread surface of the tire is vulcanized almost completely to the equator of the tire. It is characterized by providing a plurality of incisions that are inclined at an angle and whose depth changes in the middle direction.

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

First, an example of a tire obtained by the method of manufacturing a tire of the present invention d 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 s4 continuous in the circumferential direction is provided at 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, and 80 to the tire's equator C.
A carcass 7 made of cords arranged at an angle of 90° to 90', and a belt layer 8 made of steel cords on which the tread part 2 is arranged. A large number of incisions 9... inclined with respect to C are provided in the circumferential direction, and the tire 1
is manufactured by forming the green cover tire, vulcanizing it, and then forming the incisions 9. 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 forming drum, and this is placed in a mold by a conventional method and vulcanized. After that, a cut 9 is made with a knife in the ring tire taken out from the mold. Here, the cuts 9 are the main grooves 4.4 of the tread portion 2, which are carved with a sharp and relatively thin knife, bit, grindstone, saw blade, etc., with a thickness of about 3 mm or less.
This is a cut that crosses the ridge between the 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 relatively wide groove widths that cannot be formed in small tires in principle. 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. 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 approximately straight across the tread portion 2, and at a distance of 30" to 30" relative to the tire's equator C.
It is preferable to set the notch so that it is inclined at an angle of 90'', preferably in the range of 50° to 80°.If the inclination angle of the notch 9 is too small, the effect of preventing uneven wear will be reduced, and
The effect of improving wet grip properties becomes small.

Next, in the present invention, the BB cross section in FIG. 1 is shown in FIG.
As shown in FIG. 4 in cross-section C, the depth d of each cut changes in the width direction of the tread. In the B-B cross section shown in Fig. 3, the cut depth increases from the tread end in the direction of the equator C, whereas in the C-C cross section shown in Fig. 4
In the cross section, the cutting depth decreases from the tread end toward the equator C. The incisions made at regular intervals in the circumferential direction of the tire are arranged so that the depth thereof increases and decreases in the equator C direction alternately.

With this arrangement, the tread rubber at the bottom of the cut can be strengthened and damage to the tread rubber can be prevented. In addition, in the present invention, it is also possible to use a combination of a cut whose depth is uniform in the middle direction and a cut whose depth changes as described above.

Here, the depth d of the notch 9 is 50% of the groove depth D of the main groove 4.
~110%, and the interval between notches 9 is 5
~50 ts, preferably 10 to 30 ts. 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. Furthermore, several types of cuts with different groove depths d may be mixed. Note that the cut 9 is
From the viewpoint of productivity and processing accuracy, this is usually done by mechanical processing, and furthermore, by using an automatic cutting machine that can adjust the cutting position and angle. For example, this machine includes a tire mounting means for supporting the tire around a predetermined axis, a cutting means for forming a cut across the tire trend portion, and a cutting means for cutting the tire in the tread portion of the tire. and a means for moving the surface in the width direction, and the interlocking of the latter means is suppressed to make a predetermined incision on the tread surface.

As described above, in the tire manufacturing method of the present invention, the incisions are made after the tire is vulcanized, so that the incisions can be formed to have a narrow width with substantially no groove width. For this reason, compressive stress creates a strong pressure contact between the notches within the ground contact surface.
It behaves as if it were a continuous rubber band, and in response to bending stress near the ground contact edge, it jumps out without any unreasonable stress due to the notch effect acting on it, making it possible to step on it and improving rolling resistance and abrasion resistance. Furthermore, the water film is cut by the notches created by the bending deformation of the tread rubber, and
Effective drainage towards the main groove and improved wet grip. 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 and heavy vehicle tires, such as lug type, lug type, and pro rough type, but in particular, it can be applied to tires with continuous zigzag in the circumferential direction on the tread surface. Suitable for use in steel radial tires for trucks and buses, which have 2 to 5 main grooves.

Small 1dl 1000R as shown in Figures 1, 2, 3 and 4
20 steel radial tires were made with cuts according to the specifications shown in Table 1 so that the direction of change in depth was alternately reversed, and the results were evaluated for characteristics such as abrasion resistance and wet 1J wapability. It is clear that the tires produced by the tire manufacturing method of the present invention shown in Table 1 have improved mechanical characteristics.

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 by 1cm in an actual vehicle driving test is shown as a relative value.

Note 4) Measured using a transfer resistance tester.

[Brief explanation of drawings]

FIG. 1 is a partial plan view illustrating a tire obtained by the manufacturing method of the present invention, and FIGS. It is a diagram. 1-Tire, 2--Tread portion, 3--Tread surface, 4--Main groove, 9-One cut, C---Tyre equator patent applicant Sumitomo Rubber Industries Co., Ltd. agent Patent attorney Naemura Positive 1 Figure 2 Figure 2 Figure 3 Figure 4

Claims (7)

[Claims] (1) After forming a raw cover tire and vulcanizing it, a plurality of cuts are made over almost the entire tread surface of the tire at an angle inclined to the equator of the tire and whose depth varies in the middle direction. A method of manufacturing a tire, comprising: (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°. (4) The incisions are 5 to 50 in the circumferential direction of the tire.
The method for manufacturing a tire according to claim 1, characterized in that the tires are provided at intervals of (2). (5) The method for manufacturing a tire according to claim 1, wherein the tread surface of the tire has two to five zigzag-shaped main grooves continuous in the circumferential direction. (6) The depth of the cut is 50 to 110% of the depth of the main groove.
A method for manufacturing a tire according to claim 5, which is within the scope of claim 5. (7) The method for manufacturing a tire according to claim 1, wherein the tire is a steel radial tire for trucks and buses.