JPH08175115A - Pneumatic tire - Google Patents

Abstract

PURPOSE: To provide a pneumatic tire which further improves the braking ability and suppresses the uneven wear by suppressing the reduction of the block rigidity even when the siping provided on the block is increased in number. CONSTITUTION: In a pneumatic tire where a plurality of blocks 4 demarcated by a plurality of main grooves in the circumferential direction of the tire and a plurality of transverse grooves 3 in the width direction of the tire are formed in the tread surface, and sipings 5 in the width direction of the tire are provided in the blocks, ruggedness 6 of 20-300μm is provided on the inner wall surface of the sipings 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire having a block pattern, and more particularly to a pneumatic tire having a block which improves braking / driving performance by sipes.

[0002]

2. Description of the Related Art Generally, studless tires for ice and snow roads are provided with sipes on blocks having a block pattern, and the sipe has an edge effect to improve braking / driving performance on ice and snow roads. Generally, this braking / driving performance can be improved by increasing the number of sipes, but if it is too large, the bending rigidity of the block decreases and the buckling of the block increases, so the edge effect decreases. As a result, the braking / driving performance is deteriorated, and further, the bending rigidity of the block is deteriorated, so that uneven wear is likely to occur.

[0003]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a pneumatic cylinder that suppresses a decrease in block rigidity to further improve braking / driving properties and suppresses uneven wear even if the number of sipes provided in a block is increased. To provide tires.

[0004]

A pneumatic tire of the present invention that achieves this object has a plurality of main grooves in the tire circumferential direction and a plurality of lateral grooves in the tire width direction formed on a tread surface. A pneumatic tire in which blocks are formed and sipes are provided on these blocks is characterized in that unevenness of 20 to 300 μm is provided on the inner wall surface of the sipes.

As described above, the inner wall surface of the sipe is 20 to 300 μ
By providing minute irregularities of m, when the block tries to bend and deform during braking / driving of the tire, the sipe is suppressed in order to suppress large deformation of the block due to the large frictional resistance caused by the contact between the inner wall surfaces of the sipes. The edge effect is increased and the braking / driving performance is improved. Further, since large bending does not occur, uneven wear can be suppressed.

In the present invention, the irregularities on the inner wall surface of the sipe are those measured according to the definition of the Japanese Industrial Standard B0601-1994, item 5, ten-point average roughness. Hereinafter, the configuration of the present invention will be specifically described with reference to the drawings. FIG. 1 shows a tread surface of a pneumatic tire according to an embodiment of the present invention. A plurality of main grooves 2 extending in the tire circumferential direction and a plurality of lateral grooves 3 extending in the tire width direction are provided on the tread surface 1, and a large number of blocks 4 are formed by the main grooves 2 and the lateral grooves 3. These blocks 4 are provided with a plurality of sipes 5 in the tire width direction so as to extend linearly in the tire radial direction in a depth. On both inner wall surfaces of these sipes 5, as shown in FIG.
A large number of irregularities 6 of up to 300 μm are provided.

When the tire having the above-described structure travels on the road surface, the block 4 is bent by the rotation in the direction of the arrow as shown in FIG. 9, and the small block 4a is divided by the sipes 5.
Driving force is generated by the edge effect of the edge e. Further, since the inner wall surfaces of the sipes 5 are brought into close contact with each other due to the bending of the block 4, a large frictional resistance is generated based on the fine irregularities 6, and the bending deformation of the block 4 is suppressed. Therefore, the edge effect by the edge e is increased and a high driving force is generated. Further, since large bending and buckling can be suppressed, it is possible to increase the number of sipes 5 and increase the edge amount as compared with the conventional tire, and it is possible to further improve the braking / driving performance.

In the present invention, the unevenness on the inner wall surface of the sipe is 2
0 to 300 μm, more preferably 100 to 250 μm
It should be m. If the size of the unevenness is smaller than 20 μm, sufficient frictional force cannot be obtained between the inner wall surfaces, and the above-mentioned braking / driving performance cannot be obtained. In addition, the size of the unevenness is 300 μm
If it exceeds, it becomes difficult to roughen the surface of the sipe molding blade, and the sipe molding blade is 1 mm or less (that is, the sipe width is 1 mm.
In the case of the following), the strength of the sipe molding blade is reduced and it is not practical.

As shown in FIGS. 3A and 3B, the sipe provided on the block in the present invention is a sipe molding blade 15 having fine horizontal stripe-shaped irregularities 16 formed on both front and back surfaces.
It can be molded by implanting it in the block molding part of the mold. The unevenness 16 provided on both surfaces of the sipe molding blade 15 is not limited to a horizontal streak shape.
Concavities and convexities 16 processed into a net shape as in (A) and (B), and a large number of spot-shaped concavities and convexities 16 as shown in FIGS.
Etc., and the unevenness 6 on the inner wall surface of the sipe also corresponds to these. Also, the unevenness 1 of the sipe molding blade 15
6 does not necessarily have to be provided on the entire surface, and FIG.
About 1 on the implanting side (that is, the tread surface side of the block) of the sipe molding blade 15 in the examples of (B) and FIGS. 7 (A) and (B).
It may be applied only to / 2. The uneven processing of these sipe forming blades 15 is performed by machining,
It can be easily performed by chemical corrosion processing.

In the present invention, the shape of the sipe 5 in the depth direction is preferably substantially linear in the tire radial direction. Since the fine irregularities 16 are provided on the surface of the sipe molding blade 15, the straightness allows the mold releasability from the mold to be improved. Further, in the present invention, the sipe 5 in plan view may be linear in the tire width direction,
You may make it a zigzag shape like FIG. In the case of the zigzag shape, the edge length can be increased, which is effective in increasing the braking / driving force.

Further, in the present invention, the width of the sipes 5 is preferably 0.5 to 1.5 mm as an average width when measured as the distance between the intermediate positions of the heights of the irregularities 6. 0.5 m
Sipes smaller than m are practically difficult to machine. Further, if it exceeds 1.5 mm, it becomes difficult for the inner wall surfaces of the sipe 5 to come into contact with each other during braking / driving, and the bending rigidity cannot be improved due to the above-mentioned frictional resistance.

[0012]

EXAMPLE A tire size of 185 / 70R13 was used to form the block pattern of FIG. 1, and the block was provided with fine irregularities on the inner wall surface as shown in FIG. 2, and the irregularities were set to 20, 50, and 100, respectively. , 150, 250 and 30
The tire of the present invention having a thickness of 0 μm was manufactured.

On the other hand, for comparison, a conventional tire having the same structure was manufactured except that the inner wall surface of the sipe was not processed to have fine irregularities. The seven types of tires were subjected to the following braking performance test on ice, and the results shown in FIG. 10 were obtained. From the results of FIG. 10, it is understood that the tire of the present invention has improved braking performance on ice as compared with the conventional tire. [Test method for braking performance on ice] Ice temperature -5 to -8 ° C, temperature -3
The braking distance when braking (locking) from a speed of 40 km / h was measured on an ice road test course at -5 ° C.

The measurement result was evaluated by the reciprocal number, and shown by an index with the reciprocal number of the braking distance of the conventional tire being 100. The larger this index, the better the braking performance on ice.

[0015]

As described above, the pneumatic tire of the present invention has the sipe provided on the block, and the inner wall surface of the sipe is 20 to 300 μm.
Since the unevenness of the block is provided, the bending of the block during braking / driving can be suppressed by the frictional resistance generated by the contact between the sipe inner wall surfaces, so the decrease in the bending rigidity of the block can be reduced even if the number of sipes is increased. It is possible to improve the braking / driving performance based on the increase in the edge effect and also suppress the uneven wear of the block.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a block pattern in a pneumatic tire of the present invention.

FIG. 2 is a perspective view showing a block in the block pattern of FIG. 1 with a part thereof cut away.

FIG. 3 shows a sipe molding blade of a mold used for molding a tire of the present invention, (A) is a front view and (B) is a side view.

FIG. 4 shows another embodiment of the sipe molding blade, (A) is a front view and (B) is a side view.

FIG. 5 illustrates yet another embodiment of a sipe forming blade,
(A) is a front view and (B) is a side view.

FIG. 6 shows yet another embodiment of a sipe forming blade,
(A) is a front view and (B) is a side view.

FIG. 7 shows yet another embodiment of a sipe forming blade,
(A) is a front view and (B) is a side view.

FIG. 8 is a perspective view showing another example of a block in the tire of the present invention.

FIG. 9 is a schematic diagram showing a state of a block when the tire of the present invention is driven.

FIG. 10 is a graph showing the relationship between the size of the irregularities on the inner wall surface of the sipe and the braking performance on ice.

[Explanation of symbols]

1 tread surface 2 main groove 3 lateral groove 4 block 5 sipe 6 unevenness of sipe inner wall surface 15 sipe molding blade 16 unevenness of sipe molding blade

Claims (3)

[Claims] 1. A pneumatic tire in which a plurality of blocks partitioned by a plurality of main grooves in the tire circumferential direction and a plurality of lateral grooves in the tire width direction are formed on a tread surface, and these blocks are provided with sipes in the tire width direction. A pneumatic tire having 20 to 300 µm unevenness on the inner wall surface of the sipe. 2. The pneumatic tire according to claim 1, wherein the depth of the sipe is linear in the tire radial direction. 3. The pneumatic tire according to claim 1, wherein the sipe has an average width of 0.5 to 1.5 mm.