JP2002087020A - Precure tread and retreaded tire using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precure tread capable of reducing biased abrasion caused by a characteristic block shape of the precure tread and a retreaded tire using it. SOLUTION: It is possible to prevent projection of a trodding part 22A of a block 22 and a kicking part 22B in the tire diametrical direction at the time of installing the precure tread on a base tire by providing a chamfering surface by cutting the trodding part 22A and the kicking part on an end part in the circumferential direction of the block 22. Consequently, it is possible to reduce grounding pressure with a road surface on the trodding part 22A and the kicking part 22B of the block 22 and to reduce biased abrasion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precured tread and a retreaded tire using the same, and more particularly to a precured tread capable of reducing uneven wear of a step portion and a kick-out portion at both ends in a circumferential direction of a block. A retreaded tire using the same.

[0002]

2. Description of the Related Art In general, a retreaded tire is manufactured by winding a pre-cured tread around a crown portion of a base tire via a cushion rubber for bonding, and bonding the two together.

[0003] A pre-cure tread having a so-called rib pattern in which a main groove extending in the circumferential direction is formed on the tread surface and a lug groove extending in the tire width direction is not formed, the tread rubber is capable of expanding and contracting to some extent in the circumferential direction. Therefore, when wound around the crown portion of the base tire, the tread surface of the precured tread can have a curvature substantially equal to the outer peripheral curvature of the molded tire.

However, a precured tread having a so-called block pattern having a lug groove in addition to the main groove,
Because the shape change of the groove part is larger than the land part, when this pre-cure tread is wound around the crown part of the base tire,
A curvature substantially equal to the outer curvature of the molded tire could not be obtained.

That is, as shown in FIG. 9, when such a precured tread 100 is wound around a base tire, the stepped portion 102A and the kick-out portion 102B of the block 102 are moved in the tire circumferential direction of the block 102 (the direction of arrow A in FIG. 9). It has a convex shape compared to the substantially central portion 102C, and protrudes outward in the tire radial direction (hatched portion in FIG. 9).

[0006] When the vehicle runs with such tires, the contact pressure becomes maximum at the stepped portion 102A and the kick-out portion 102B of the block 102. Step 102 of block 102
The tire in which the A and the kick-out portion 102B have a convex shape, in particular, the step-in portion 102A and the kick-out portion 102B as compared with a general pneumatic tire manufactured by a mold having a constant outer peripheral curvature.
In the width direction, the uneven work (step wear) of the step portion 102A and the kick-out portion 102B is promoted, and the derived block punch, wavy wear, and diagonal wear are deteriorated.

[0007] Further, due to the side force received from the road surface and the widthwise expansion and contraction of the belt, widthwise wear work is generated on the block tread surface, which causes uneven wear in the tread portion 102A and the kick-out portion 102B. I was

[0008]

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a precured tread and a retreaded tire which can reduce uneven wear caused by a block shape peculiar to a precured tread. And

[0009]

In the pre-cure tread according to the first aspect, the main groove and the tire are attached to the crown portion of the base tire excluding the tread and extend on the tire tread side along the circumferential direction of the tire. A precured tread in which a block is formed by a lug groove extending along the width direction, wherein a chamfered surface with a reduced block height is provided at both ends in the circumferential direction of the block.

Next, the function and effect of the precured tread according to the first aspect will be described.

When a conventional pre-cured tread having a block formed on a tread surface is adhered to a crown portion of a base tire, a tread portion and a kick-out portion of the block become convex outward in the tire radial direction. For this reason, there is a problem that the contact pressure with the road surface is maximized at the stepping portion and the kicking portion which are both ends in the circumferential direction of the block, and uneven wear is promoted.

Here, in the present invention, since the chamfered surface where the block height is reduced is provided at both ends in the circumferential direction of the block, even if the precured tread is attached to the crown portion of the base tire, the block is not damaged. It is possible to prevent the stepping portion and the kicking portion, which are both ends in the circumferential direction, from protruding in the tire radial direction.
For this reason, the contact pressure with the road surface can be reduced at the stepping portion and the kicking portion of the block, and uneven wear can be reduced.

In the pre-cured tread according to the second aspect, the chamfered surface is formed up to the center in the circumferential direction of the block.

Next, the function and effect of the precured tread according to the second aspect will be described.

In the present invention, since the chamfered surface is formed up to the central portion in the circumferential direction of the block, the ground contact pressure can be reduced not only at both ends in the circumferential direction of the block but also in the central portion in the circumferential direction. Uneven wear can be reduced.

[0016] In the pre-cure tread according to claim 3, when the pre-cure tread is attached to the base tire,
The circumferential radius of curvature of the surface of the block is substantially equal to the circumferential radius of curvature of the tire after molding.

Next, the function and effect of the precured tread according to the third aspect will be described.

When the precured tread is adhered to the base tire, since the circumferential radius of curvature of the surface of the block is substantially equal to the circumferential radius of curvature of the molded tire, the entire block projects outward in the tire radial direction. Therefore, the contact pressure acting on the entire block can be reduced, and uneven wear can be reduced.

In the precured tread according to the fourth aspect, the falling height on the chamfered surface of the block gradually increases as approaching the circumferential end of the block.

Next, the function and effect of the pre-cured tread according to claim 4 will be described.

Since the falling height of the chamfered surface of the block gradually increases as it approaches the circumferential end of the block, the contact pressure at the circumferential end of the block, which tends to protrude, can be effectively reduced, and uneven wear is effectively reduced. it can.

According to a fifth aspect of the present invention, the chamfered surface is provided at each corner at both ends in the circumferential direction of the block.

Next, the function and effect of the pre-cured tread according to claim 5 will be described.

Since the chamfered surface is provided at each corner at both ends in the circumferential direction of the block, the contact pressure at each corner can be reduced and uneven wear can be prevented. Further, by providing the chamfered surface only at each corner, the rigidity of the block can be maintained.

In the pre-cured tread according to the sixth aspect, the chamfer length of the chamfer surface along the block circumferential direction is as follows:
The length is 0.3 times or more and 0.5 times or less the circumferential length of the block.

Next, the function and effect of the precured tread according to claim 6 will be described.

The chamfered length of the chamfered surface along the circumferential direction of the block is 0.3 times or more and 0.5 times or less the circumferential length of the block, so that the ground pressure at the circumferential end of the block can be more effectively reduced. And uneven wear can be reduced.

Conversely, if it is larger than 0.5 times,
The sum of the chamfer lengths is longer than the circumferential length of the block, which is inappropriate.

The chamfered length of the chamfered surface along the block circumferential direction refers to the chamfered length of the chamfered surface provided at one circumferential end of the block along the block circumferential direction.

[0030] In the precured tread according to claim 7, the chamfered length along the block width direction of the chamfered surface is:
The length is 0.2 times or more the length of the block in the tire width direction.

Next, the function and effect of the precured tread according to claim 7 will be described.

By setting the chamfer length of the chamfer surface along the block width direction at least 0.2 times the length of the block in the tire width direction, the contact pressure at the circumferential end of the block can be reduced more effectively. , Uneven wear can be reduced.

[0033] As shown in the pre-cured tread according to claim 8, the chamfered surface is preferably formed in a straight line or a curved line.

According to a ninth aspect of the present invention, there is provided a retreaded tire including the precured tread according to any one of the first to eighth aspects.

Next, the operation and effect of the retreaded tire according to claim 9 will be described.

In the retreaded tire provided with the precured tread according to any one of claims 1 to 8, uneven wear of the stepped portion and the kick-out portion of the block of the precured tread can be reduced. For this reason, compared with the conventional retreaded tire, the life running distance of the tire can be extended.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A pre-cured tread according to a first embodiment of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, a retread tire 10 is manufactured by vulcanizing and bonding a vulcanized pre-cured tread 16 to a crown portion 12A of a base tire 12 via a seed-like cushion rubber 14.

As shown in FIG. 1, Precured tread 1
6, a circumferential groove 18 (main groove) extending in the tire circumferential direction (the direction of arrow A in FIG. 2) is formed on the tread surface 16A.
A lug groove 20 (see FIG. 2) extending in the tire axial direction (the direction of arrow B in FIG. 1) is formed. The circumferential groove 18 and the lug groove 2 are provided on the tread surface 16A of the precured tread 16.
A plurality of blocks 22 are formed by 0 and a so-called block pattern is formed.

As shown in FIGS. 2 and 3, the step 22A and the kick-out portion 22B, which are the circumferential ends of the block 22 provided on the tread surface 16A of the pre-cured tread 16, have the ends of the block 22. A chamfered surface is provided in which the height of the block decreases as much as possible.

The chamfered surface is made of Precured Red 1
When 6 is attached to the base tire 12, the distance R1 (the radius of curvature in the circumferential direction, hereinafter the same) from the tire center O to the surface of the step portion 22A and the kick-out portion 22B of the block 22 is blocked from the tire center O. The tire diameter of the stepped portion 22A and the kick-out portion 22B of the block 22 of the pre-cured tread 16 is set to be substantially equal to the distance R2 (the radius of curvature in the circumferential direction, the same applies hereinafter) to the surface of the substantially central portion 22C in the longitudinal direction of the block 22. It is formed by reducing the thickness in the direction.

In particular, at the tire circumferential end of the stepping portion 22A of the block 22 and the tire circumferential end of the kick-out portion 22B, the block 22 is cut by d1.

In other words, when the pre-cured tread 16 is placed on a plane, the height of the stepped portion 22A and the kick-out portion 22B of the block 22 are adjusted to the longitudinal central portion 22 of the block 22.
When the precured tread 16 is wound around the crown portion 12A of the base tire 12, the surface of the step portion 22A and the kick-out portion 22B of the block 22 extend along the tire circumferential direction. The entire surface of the block 22 extending in the tire circumferential direction is formed to have substantially the same curvature as the curvature S (see FIG. 2) of the molded tire.

Here, as shown in FIG. 3, the chamfering length W1 of the chamfered surface along the block circumferential direction is set to 0.3 to 0.5 times the circumferential length P1 of the block 22. .

The chamfering length W2 of the chamfered surface along the block width direction is equal to the length P2 of the block 22 in the width direction.
Is set to 0.2 times or more, and in the present embodiment, W2
= P2 (1.0 times P2).

The distance R1 from the center O of the tire to the surface of the step 22A and the kick-out portion 22B of the block 22 is equal to the center O of the tire even if the tread portion 22A and the kick-out portion 22B of the block 22 are not cut in a curved shape. From the center 22C of the block 22 to the tire circumferential end of the stepped portion 22A or the tire circumferential end of the kick-out portion 22B. It may be cut in a straight line so as to gradually become deeper.

Here, the stepped portion 22A of the block 22 refers to the block 2 when the retreaded tire 10 having the precured tread 16 is mounted on the vehicle and the vehicle is run.
2 refers to the part that first comes into contact with the road surface, while
2B indicates the last part of the block 22 that comes into contact with the road surface.

In this embodiment, one block 2
Although the description has been given of cutting the second step portion 22A and the kicking portion 22B, the present invention is not limited to this. For example, only one of the stepping portion 22A and the kicking portion 22B may be cut.

As shown in FIG. 4, one block 30 has an outer side in the tire axial direction (the direction of arrow C in FIG. 4).
, Only the step-in portion 30A and the kick-out portion 30B which are located at the same position may be cut off. In such a case, for example, it is preferable to cut in a curved shape from the stepped portion 30A located on the inner side in the tire axial direction (the direction opposite to the arrow C in FIG. 4) to the stepped portion 30A located on the outer side in the tire axial direction. In addition, it is preferable to cut in a curved shape from the ejection portion 30B located on the inner side in the tire axial direction (the direction opposite to the arrow C in FIG. 4) to the ejection portion 30B located on the outer side in the tire axial direction.

Although not shown, the stepped portion 30A of the block 30 is formed so as to be linear in the tire circumferential direction (arrow A direction in FIG. 4) and the tire axial direction (arrow B direction in FIG. 4). You may cut it. Similarly, the kick-out portion 30B of the block 30 may be cut so as to be linear along the tire circumferential direction (the direction of the arrow A in FIG. 4) and the tire axial direction (the direction of the arrow B in FIG. 4).

Further, as shown in FIG. 5, the four corners (corners) located at the step portion 40A and the kick-out portion 40B of one block 40 are defined in the tire circumferential direction (arrow A direction in FIG. 5) and the tire axial direction. It may be cut along a curve along the direction of arrow B in FIG.

Although not shown in the figure, not only in the case where the block 40 is cut in a curved shape, but also in the
May be cut linearly so as to gradually increase in depth from the tire circumferential end and the tire axial end.

As described above, it is effective to cut all corners of the block 40, but one or more corners may be cut.

Next, the operation and effects of the precured tread according to the present embodiment will be described.

As shown in FIG. 9, when the conventional precured tread 100 having the block 102 formed thereon is attached to the crown portion of the base tire, the stepped portion 102 of the block 102 is formed.
A and the kick-out portion 102B are convex outward in the tire radial direction.
For this reason, the contact pressure with the road surface is maximized at the stepped portion 102A and the kick-out portion 102B of the block 102, and there has been a problem of promoting uneven wear.

Therefore, as shown in FIGS. 1 to 3, the thickness of the stepped portion 22A and the kick-out portion 22B of the block 22 of the precured tread 16 in the tire radial direction is reduced, and the precured tread 16 is attached to the base tire 12. When affixed, the tread portion 22A and the kick-out portion 2 of the block 22 from the tire center O
The distance R1 to the 2B surface is set to the block 2 from the tire center O.
2 is substantially equal to the distance R2 to the surface of the substantially central portion 22C, so that the step 22A and the ejection portion 2 of the block 22 are formed.
2B can be prevented from protruding outward in the tire radial direction.
For this reason, the step portion 22A and the ejection portion 22 of the block 22
In B, the contact pressure with the road surface can be reduced, and uneven wear can be reduced.

In particular, the precured tread 1 of the present embodiment
The retreaded tire 10 using No. 6 can extend the life traveling distance of the retreaded tire 10 as compared with the conventional retreaded tire.

Next, a precured tread according to a second embodiment of the present invention will be described.

The same components as those in the first embodiment are denoted by the same reference numerals, and the description will not be repeated.

In the first embodiment, the precured tread 1
6 is attached to the base tire 12, the distance R1 from the center O of the tire to the surface of the step portion 22A and the kick-out portion 22B of the block 22 is the distance R2 from the center O of the tire to the surface of the substantially central portion 22C of the block 22. The thickness of the stepped portion 22A and the kick-out portion 22B of the block 22 of the precured tread 16 in the tire radial direction was formed to be substantially equal to the above.

In the retreaded tire of this embodiment, as shown in FIG. 6, the stepped portion 50A and the kick-out portion 50B of the block 50 are further thinned, and the precured tread 52 is attached to the base tire 1.
2 (see FIG. 1), the distance R3 (the radius of curvature in the circumferential direction, hereinafter the same) from the center O of the tire to the surface of the step portion 50A and the kick-out portion 50B of the block 50 from the center O of the tire. This is shorter than the distance R2 to the surface of the substantially central portion 50C of the block 50 in the tire circumferential direction (the direction of arrow A in FIG. 6).

That is, from the tire center O to the block 50
When a circle (outer curvature S of the molded tire) is drawn with a distance R2 to a substantially central portion 50C in the longitudinal direction as a radius, a block 50 is obtained.
Are formed so that the stepped portion 50A and the kick-out portion 50B are located inside the circle in the tire radial direction. In particular, the distance R3 from the tire center O to the tire circumferential end of the stepped portion 50A of the block 50 and the tire circumferential end of the kick-out portion 50B.
Is the center 5 in the longitudinal direction of the block 50 from the tire center O.
It is cut so as to be shorter by d2 than the distance R2 to 0C. Therefore, at the tire circumferential end of the stepped portion 50A of the block 50 and the tire circumferential end of the kick-out portion 50B, it is cut deeper by d2 than those of the block 22 of the pre-cured tread 16 of the first embodiment. D in total compared to Precured Tread 100 (see FIG. 9)
This means that 1 + d2 has been removed.

In the pre-cured tread 52 of this embodiment, the step 50A and the kick-out unit 50B of the block 50 are provided.
Does not protrude outward in the tire radial direction, and furthermore, the stepped portion 50A and the kick-out portion 50B are located inward in the tire radial direction from the substantially central portion 50C of the block 50 in the tire circumferential direction. Compared with the pre-cured tread 16, uneven wear can be reduced more effectively.

Further, the precured tread 5 of the present embodiment
The retreaded tire using No. 2 can extend the life running distance of the retreaded tire compared to the retreaded tire 10 using the precured tread 16 of the first embodiment.

Here, the effect of the retreaded tire using the precured tread of the present invention will be described with reference to the graph shown in FIG.

In the graph shown in FIG. 7, the vertical axis indicates the step amount (mm) due to uneven wear at the tire circumferential end of the stepping portion of the block or the tire circumferential end of the kicking portion, and the horizontal axis indicates the traveling distance. 5 is a graph showing a relationship between a traveling distance and a step amount by taking a graph.

Here, the curve A in FIG. 7 is a curve showing the performance of the retread tire using the conventional precured tread, and the curve B is the retread tire using the precured tread of the first embodiment of the present invention. A curve showing the performance of
Is a curve showing the performance of a retreaded tire using the precured tread of the second embodiment of the present invention.

As shown by curve A in FIG.
In the conventional retread tire in which the second stepped portion 102A and the kick-out portion 102B protruded outward in the tire radial direction, the step amount reached 3 mm as the traveling distance increased. Retreaded tire 10 has a level difference of 2
mm. As a result, the retread tire 10 using the precured tread 16 of the first embodiment is compared with the retread tire using the conventional precured tread 100.
It was found that uneven wear of the steel was reduced.

Further, in the retreaded tire using the precured tread 52 of the second embodiment of the present invention shown by the curve 3, the step amount was reduced to 1 mm. That is, in the retread tire using the precured tread 52 of the second embodiment, the retread tire 1 using the precured tread 16 of the first embodiment is used.
The step amount was smaller than 0. As a result, in the retreaded tire of the second embodiment, the retreaded tire 10 of the first embodiment is used.
It was found that uneven wear was further reduced.

Next, based on the graph shown in FIG. 8, the relationship between the volume of the unevenly worn block and the shaving dimensions at the tire circumferential end of the stepped portion of the block and the kick-out portion of the block will be described. I do.

In the graph shown in FIG. 8, the ordinate represents the uneven wear volume of the block, and the abscissa represents the cutting dimension d at the end in the tire circumferential direction of the kick-out portion of the block. 3 is a graph showing the relationship of

As shown in the graph of FIG. 8, a retread tire using the precured tread 16 of the first embodiment indicated by a point B is compared with a retread tire using the conventional precured tread 100 indicated by a point A. At 10, the uneven wear volume decreases,
Further, the precured tread 5 of the second embodiment indicated by point C
In the retreaded tire using No. 2, it was found that the uneven wear volume was further reduced as compared with the retreaded tire 10 of the first embodiment.

As a result, the precured tread 1 of the present invention
It was confirmed that the retreaded tires using Nos. 6 and 52 had less uneven wear than the retreaded tires using the conventional precured tread 100.

[0074]

According to the precured tread of the present invention,
The uneven wear caused by the block shape unique to the precured tread can be reduced.

Further, according to the retreaded tire of the present invention, the life running distance of the retreaded tire can be extended.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in the tire width direction of a retreaded tire using a precured tread according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an outer peripheral curvature of the precured tread according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a block formed on a tread surface of the precured tread according to the first embodiment of the present invention.

FIG. 4 is a perspective view of a block different from the block shown in FIG. 3;

FIG. 5 is a perspective view of a block different from the block shown in FIG. 3;

FIG. 6 is a diagram showing an outer peripheral curvature of a precured tread according to a second embodiment of the present invention.

FIG. 7 is a graph comparing the relationship between the step amount of a block due to uneven wear and the actual vehicle traveling distance between a conventional retread tire and the retread tire of the present invention.

FIG. 8 is a graph showing the relationship between the uneven wear volume of the block and the cutting dimensions of the stepped portion and the kick-out portion of the block.

FIG. 9 is a diagram showing an outer peripheral curvature of a conventional precured tread.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 10 retreaded tires 12 tires 12A crown 16 precured tread 22 blocks 30 blocks 40 blocks 50 blocks 52 precured treads

Claims (9)

[Claims] 1. A pre-adhesive device which is affixed to a crown portion of a base tire excluding a tread and has a block formed by a main groove extending along a circumferential direction of the tire and a lug groove extending along a tire width direction on a tire tread side. A cured tread, wherein a chamfered surface having a reduced block height is provided at both circumferential ends of the block. 2. The precured tread according to claim 1, wherein the chamfered surface is formed up to a central portion in a circumferential direction of the block. 3. When the precured tread is attached to the base tire, a circumferential radius of curvature of a surface of the block is substantially equal to a circumferential radius of curvature of the molded tire. 3. The pre-cured tread according to 2. 4. The pre-cure tread according to claim 1, wherein a drop height of the chamfered surface of the block gradually increases as approaching a circumferential end of the block. 5. The precured tread according to claim 1, wherein the chamfered surface is provided at each corner at both ends in a circumferential direction of the block. 6. The chamfered length of the chamfered surface along the circumferential direction of the block is not less than 0.3 times and not more than 0.5 times the circumferential length of the block.
Precured tread according to any one of the above. 7. The chamfer length of the chamfer surface along the block width direction is 0.2 times the length of the block in the tire width direction.
The precured tread according to any one of claims 1 to 6, wherein the precured tread is twice or more. 8. The precured tread according to claim 1, wherein the chamfered surface is formed in a straight line or a curved line. 9. A retread tire comprising the precured tread according to claim 1. Description: