JPS60240507A - Low noise multi-siping tire - Google Patents

Abstract

PURPOSE:To reduce running noise of the captioned tire, whose tread-to-ground contact surface is provided with knife-cuts, by providing the pitch arrangement of the knife-cuts irregularly. CONSTITUTION:The periphery of a tire tread surface is divided into 12 equal segments. One segment SG of which is formed by a pitch arrangement of SSSMLMSMMSLMLLLLLSM, combining three kinds of pitches; S, M, and L. This pitch arrangement is repeated in the above twelve segments. In this case, the individual pitch length and the pitch length ratios are predetermined. In other words, M/S is set at 1.05 or more, while L/M is set at 1.35 or less. If the pitch length ratio comes out of these ranges both the strength and the wet grip performance of a tire decline. With this constitution, the decline of both the directional stability on a dry road surface and the performance on a wet road surface can be prevented, and at the same time the tread-pattern-induced noise can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a multi-siping tire in which a large number of knife cuts are made across the entire width of the tread in the direction across the tread on the tread surface of the tire, and the arrangement pitch of the knife cuts is made irregular. This invention relates to a low-noise tire that reduces running noise by engraving.

In recent years, the demand for lower noise levels in automobiles has become more severe from an environmental perspective, and along with this, there has also been a demand for lower noise levels in tires.

Meanwhile, in Japan as well, the development and expansion of the expressway network is progressing, and the radius of movement of trucks, buses, etc. is expanding accordingly. Therefore, a vehicle may encounter various weather conditions during one operation, and there has recently been an increasing demand for tires that can overcome these conditions and drive safely.

Conventionally, rib tires with multiple grooves arranged in a zigzag shape in the circumferential direction on the tread surface have been mainly used as tires for running on paved roads such as expressways. This type of ribbed tire has been mainly used because it has high directional stability and has great advantages in terms of pattern noise and fuel consumption by tires, but this type of ribbed tire has inferior braking force and turning performance on wet roads. Therefore, this has become a major problem as the service becomes more widespread. In order to compensate for the above-mentioned problems of ribbed tires, block patterns that can effectively eliminate water interposed between the tread surface and the road surface, and so-called multi-siping tires, which have multi-siping on ribbed tires, have recently been developed for use in all-weather tires. It has come to be valued as a model tire.

However, such block pattern and multi-siping tires have the disadvantage that they have large pattern noise, and block patterns generally wear out quickly, making it difficult to use them all year round.

The object of the present invention is to provide a tire that can effectively eliminate the problems of conventional multi-siping tires, namely, directional stability on dry road surfaces, braking performance on wet road surfaces, turning performance, wear resistance, and low fuel consumption. The purpose is to provide a tire that reduces tire pattern noise without impairing characteristics such as uneven wear resistance. ), rib or block pattern, the tire's tread surface is made with multiple cuts (
The siping is characterized by being arranged at a combination of multiple or more pitches, that is, at irregular pitches.

Below, we will first explain how to make the incision, which is essential for carrying out the present invention.

In FIG. 1 showing the developed right half of the tread portion 2 of the multi-siping tire 1 and FIG. If the tread portion 2 is divided into a tread center portion 5 and a pair of left and right tread shoulder portions 6 by providing a shaped main groove 4 at the center and both sides,
Also, inside the tire is 80° to 90° to the equator C of the tire.
A carcass 7 made of steel cords or fiber cords arranged at an angle of 0.degree., and a belt layer 8 made of steel cords disposed on the tread portion 2 are provided. A large number of notches 9 inclined with respect to the equator C of the tire 1 are provided in the circumferential direction, and the main groove 4 of the tire 1 may be formed by a mold during vulcanization, but if there is no pattern. Grooving may be performed after vulcanizing a plain tire. The raw cover tire has a toroidal shape in which a carcass layer 7, a belt layer 8, a bead part (not shown), and a tread part 2 are combined on a molding drum, and this is vulcanized in a mold by a conventional method. After that, a cut 9 is made with a knife in the original tire taken out from the mold.

Here, the cut 9 is a cut that crosses the protrusion between the main grooves 4 and 4 of the tread portion 2, cut by a sharp and relatively thin knife, bit, grindstone, or saw blade with a thickness of about 3 mm or less. The groove can be formed without substantially having a groove width, and as described above, it is provided across the entire width of the tire 1 at an angle with respect to the equator C of the tire. The lateral grooves of conventional tires, which are formed at the same time as vulcanization in a mold equipped with blades, cannot be made narrow in principle and have a relatively wide groove width, but multi-siping tires 1 In this case, since the groove width of the notch 9 can be practically ignored, the compressive stress acting within the ground plane causes the two edges of the notch 9 to be strongly pressed against each other, 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 relieve the stress.This not only prevents shoulder drop wear of the tread portion 2, but also reduces bounce during running. broth,
Depressing, that is, grip performance is improved. In addition, both edges of the notch 9 that are opened during bending deformation cut the water film,
Improves drainage in the four directions of the main groove.

In order to enhance this effect, the cut 9 is set to be substantially straight across the entire width of the tread portion 2 and inclined at an angle of 30° to 90° with respect to the equator C of the tire, preferably in the range of 50° to 80°. It is better to do so. 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.

Next, as shown in FIG. 3 which shows a cross section taken along line BB in FIG. 1, and shown in FIG. 4 which shows a cross section taken along line C-C in FIG. 1, the depth d of the cut changes in the width direction of the tread. In the B-B cross section shown in Figure 3, the cutting depth increases from the tread end in the direction of the equator C, whereas in the CC cross section shown in Figure 4, the cut depth increases from the tread end in the equator C direction. Cut depth is reduced. 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. This arrangement strengthens the tread rubber at the bottom of the cut,
Damage to the tread rubber can be prevented. In addition, in the present invention, it is also possible to use incisions with uniform depth in the width direction and incisions with varying depths. Here, the depth d of the cut 9 is 50 to 50% of the groove depth D of the main groove 4.
The range is 110%.

Although the above description has mainly been about the method of making the cuts, the inventor of the present invention has succeeded in providing the desired tire as a result of various studies regarding the arrangement pitch of the cuts. The pitch arrangement of the notches, which is a feature of the present invention, will be explained below based on one embodiment.

For a tire size 10.0OR2914PR, the circumference of the tread surface is divided into 12 equal parts, and the pitch arrangement of the segment (SG) is divided into three types of pitches S and M.
, L is the following array. (FIG. 5) SSSSMLMSMMSLMLLLLLLS'MBy repeating the segments in this arrangement 12 times, a pattern for one circumference of the tread surface is constructed.

The size of each pitch is shown in the table below.

This is the pitch S, M, L length ratio M/S.

L/M is set in the following range.

■, 05≦M/S or L/M≦1.35 this ratio is 1.0
If it is less than 5, the strength of the rubber between the pitches will be too low and the rubber in this area will be easily damaged. Also 1.3
When it is 5 or more, the pitch interval becomes too wide and the wet grip deteriorates.

Therefore, the most preferable value for the ratio of M/S or L/M is in the range of 1.15 to 1.25.

The pitch length of the cuts is in the range of 5 to 50 mm, preferably 10 to 30 mm.If an excessively large number of cuts are provided, the rigidity of the tread 2 will be reduced and the running stability will be affected.
This will impair wear resistance.

Note that the incisions 9 are made by normal machining from the viewpoint of productivity and processing accuracy, and further by using an automatic incision machine that can adjust the incision 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 entire width of the tire tread, and a cutting means for cutting the tire on the tread surface of the tire. The tread includes means for moving the tread in the width direction, and the interlocking of the latter means is suppressed to make a predetermined incision on the surface of the tread portion.

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 small 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 tire types such as passenger car tires and heavy vehicle tires, such as lug type, lug type, and block type. It is suitably adopted for steel radial tires for trucks and buses, which are provided with 2 to 5 tires.

Example: The 10.0OR20 steel radial tires shown in Figures 5, 6, and 7 were cut according to the specifications shown in Table 1 so that the directions of depth change were alternately opposite. Table 1 shows the results of evaluating characteristics such as , abrasion resistance, and wet grip properties. It is clear that the tire manufactured by the tire manufacturing method of the present invention has improved mechanical characteristics.

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

Note 2) The distance traveled until the tread wears 1 mm in actual vehicle driving tests is shown as a relative value.

Note 3) Measured using a transfer resistance tester.

Note 4) Place the sound collection microphone directly next to the vehicle and from the center of the vehicle by 7.5 mm.
Measurements were taken in an anechoic chamber with a height of 1.2 m above the ground plane.

[Brief explanation of drawings]

FIG. 1 is a partial plan view illustrating a multi-sipe tire, and FIGS. 2, 3, and 4 are sectional views taken along line A-Δ, line BB, and line CC. FIG. 5 is a partial plan view of a pattern showing an example of a low-noise multi-siping tire according to the present invention, FIG. 6 is a partial plan view of a pattern showing an example of a conventional multi-siping tire, and FIG. 7 Figures 8 and 9 are partial pattern plan views showing an example of a normal groove pattern tire before siping is added.
The figure shows frequency analysis values of sound pressure levels showing the noise test results of tires with these three types of patterns (Figures 5 to 7). ■... Tire, 2... Tread part, 3... Tread surface, 4... Main groove, 9... Notch, C...
・Tire equator Figure 1 Figure 2 Figure 3rI! J Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 ■ 01 Frequency (Hz)

Claims (3)

[Claims] (1) After forming a raw cover tire and vulcanizing it, in a multi-siping tire, multiple incisions are carved at an angle inclined to the equator of the tire over almost the entire width of the tread surface of the tire. A tire characterized in that the arrangement is composed of a combination of two or more types of pitches. (2) The cut is 5 to 50 m in the circumferential direction of the tire.
The tire according to claim 1, characterized in that the punches are provided at intervals of m. (3) SUM<L... of the plurality of pitch lengths in order of shortest to shortest.
..., the ratio of adjacent pitches M/S, L
2. The tire according to claim 1, wherein /M is in the range of 1.05 to 1.35.