JPH06262703A - Precure tread for recycling and recycled pneumatic tire - Google Patents

Abstract

PURPOSE:To provide a precure tread which always make possible bonding between blocks without reducing the productivity and a recycled tire made from it. CONSTITUTION:A long, large block 30 is arranged in a row of blocks A, B, C, D, E which is installed on a precure tread composed of a vulcanized rubber belt 10. The precure tread is cut at the position of the block 30. The cross sections are prepared to be bonded to each other, and shallow channels or sipes 4 are installed on the surface of the block 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a retread pre-cure tread having a block pattern and a pneumatic retread tire using the same.

[0002]

2. Description of the Related Art In general, heavy duty pneumatic tires for trucks, buses, etc., are cut and buffed on the tread surface when the tread has a few remaining grooves to reach the end of its service life. As a tire, it will be reused as a retreaded tire by attaching a new tread again.

As a tread used for such a retreaded tire, a precure tread in which an arbitrary pattern is provided on the surface of a belt-shaped vulcanized rubber plate is used. This belt-shaped precure tread is cut into a certain length according to the circumference of the base tire when manufacturing a retreaded tire, and it is wound around the outer periphery of the base tire so that both ends are joined and integrated. There is.

However, in the case where the pattern on the surface of the precure tread is a block pattern, since the precure tread has a sub-groove that crosses the longitudinal direction, when the precure tread is cut into a certain length according to the outer peripheral length of the base tire, The cutting position may coincide with the position of the sub groove. Therefore, when the cut end surfaces are joined to each other on the base tire, the sub-grooves are joined to each other or the sub-grooves and the blocks are joined to each other.

FIGS. 3 and 4 show planes in which pre-cured treads each having a conventional block pattern are wound around a base tire, and cut end faces are joined at a joint S. The pre-cure tread is provided with a main groove 1 in the longitudinal direction and a sub groove 2 in the width direction, and block rows A to E in which a large number of blocks 3 are arranged are formed. And in each of the block columns A to E, FIG.
Not only the blocks 3 are joined to each other as shown in FIG. 5A, but the sub-grooves 2 are joined to each other as shown in FIG. The groove 2 may be joined. However, the joint at the joint S is shown in FIG.
When the sub-grooves 2 are joined together as shown in FIG. 5B or between the block 3 and the sub-groove 2 as shown in FIG. 5C, the joining area is smaller than when the blocks 3 are joined together. Therefore, there is a problem that it is easily peeled off and durability is lowered.

In order to solve such a problem, when cutting the pre-cure tread according to the outer peripheral length of the base tire, it is necessary to carefully cut it while searching for a position where all blocks are bisected at the same time. However, the position where the blocks of the entire block row are bisected at the same time is only a very limited region as shown by hatching in FIG. 6, so that the cutting work is extremely troublesome and the productivity is significantly reduced. It is inevitable.

[0007]

An object of the present invention is to produce a retreaded tire having a block pattern, from a precure tread and a precure tread capable of always joining blocks without lowering productivity. To provide a manufactured pneumatic retreaded tire.

[0008]

The pre-cured tread for rehabilitation of the present invention which achieves such an object is a pre-cured tread in which a plurality of block rows are provided along the longitudinal direction on the surface of a belt-shaped vulcanized rubber plate. It is a cure tread, and at the position corresponding to the circumference of the base tire, long blocks having a block length larger than the largest block among the blocks regularly arranged in each of the plurality of block columns are arranged side by side. In addition, a shallow groove or sipe is provided on the surface of the long block.

Further, in the pneumatic retreaded tire of the present invention, a plurality of block rows are provided on the surface of a belt-shaped vulcanized rubber plate along the longitudinal direction thereof, and each block row is regularly arranged in each block row. A large block having a block length larger than the maximum block is arranged side by side, and a pre-cure tread provided with a shallow groove or a sipe on the surface of the large block is provided at an intermediate position of the large block in accordance with the circumferential length of the base tire. It is characterized in that it is cut at the same time and is wound around the outer periphery of the base tire to abut and join the block cut end faces in all the block rows.

Since the large blocks are arranged in the block row provided on the belt-shaped pre-cure tread in accordance with the circumferential length of the base tire, the operator takes great care by placing the large blocks at the cutting position. It is possible to cut at the positions of the blocks without paying attention, and the blocks can be joined to each other in all of the plurality of block rows.

Further, since the joining portion where the long blocks are joined together is larger than the other regular blocks,
Although only this portion tends to be unevenly worn, the shallow groove or sipe is provided in the long block to reduce the rigidity as much as other blocks, so that it is possible to reduce the occurrence of uneven wear. Hereinafter, the present invention will be specifically described with reference to the drawings.

FIG. 1 shows one of the precure treads of the present invention.
It is a top view which shows an example. In FIG. 1, the precure tread is provided with a plurality of main grooves 1 extending in the longitudinal direction and a large number of sub-grooves 2 crossing these on one side of a belt-shaped vulcanized rubber plate 10. A plurality of block rows A, B, C, D, E in which a large number of blocks 3 divided into 2 are arranged are formed.

Each of the block rows A, B, C, D and E is provided with a long block 30 at each position in the longitudinal direction corresponding to the tire circumference of the base tire, and these long blocks 30 are vulcanized. The rubber plates 10 are arranged side by side. Block length P _A, P _B, P of each long block 30
_C, P _{D, and} P _E are block strings A, B, C, D, and
It is larger than any of the regular blocks 3 arranged in E. Preferably, the block lengths P _A, P _B, P _C, P _{D, and} P _E of the long block 30 are 2 to 3 of the maximum block length among the regular blocks in each block string.
It is desirable that the range is doubled.

The long block 30 is provided with a sipe 4 in the longitudinal direction which is connected to the sub groove 2. A shallow groove may be provided instead of the sipe 4. Since these sipes and shallow grooves are provided so that the rigidity of the long block 30 is equal to that of the regular block 3, the number thereof is not particularly limited as long as the purpose can be achieved. Also,
Both ends of the sipe and the shallow groove do not necessarily have to be connected to the sub groove 2. Further, the sipes and the shallow grooves can be provided so as to intersect the longitudinal direction. However, these sipes and shallow grooves should not reduce the bonding strength of the bonding portion S, and therefore the depth is preferably 40% or less of the depth of the main groove 1.

When a retreaded tire is manufactured using the above-mentioned pre-cure tread, it is cut into a certain length according to the outer peripheral length of the base tire, and it is attached so as to be wound around the outer periphery, and the cut end faces are Must be joined. However, in the above-mentioned precure tread, since the long block rows 30 are arranged side by side in each of the block rows A to E at positions corresponding to the outer peripheral length of the base tire, the long blocks of all the block rows A to E are arranged. A longitudinal allowance region L that allows the 30 to be bisected simultaneously can be ensured as shown.

Therefore, when the operator cuts the precure tread according to the outer peripheral length of the base tire, the operator can easily secure the adjustment allowance to match the outer peripheral length of the base tire and easily perform the operation on all the block rows A to E. The large block 30 can be bisected at the same time. The pre-cure tread thus cut is wound around the base tire, and the cut end surfaces are joined at the joining portion S to manufacture a retreaded tire in which the long blocks 30 are newly joined for each block row A to E. be able to. Therefore, it is possible to increase the bonding strength at the bonding portion S and reduce the peeling occurrence rate.

Further, since the long block 30 is provided with a shallow groove or sipe, and the rigidity thereof is set to be equal to that of the regular block 3, wear occurs such that only the long block of the joint S is unevenly worn. Can be suppressed.

[0018]

EXAMPLE A precure tread of the present invention shown in FIG.
A tire size 1000R20 14 was prepared using the same comparative precure tread as in FIG. 1 except that no sipe was provided, and the conventional precure tread shown in FIG. 6, respectively.
Three types of PR retread tires were produced for 50 tires.

With respect to each of the retreaded tires of the present invention tire, the comparative tire and the conventional tire, the ratio at which the joining of blocks at the joining portion is obtained in all the block rows, and the peeling occurrence rate and uneven wear occurrence rate by the following method are shown. When evaluated, the results shown in Table 1 were obtained. Peeling rate evaluation method : Among the defective tires collected from the general market, the number of tires with peeled joints of the precure tread is divided by the number of retreaded tires produced at the same time to obtain the failure rate. Was calculated, and the values of the tire of the present invention, the comparative tire, and the conventional tire were compared. The peeling occurrence rate of the conventional tire is expressed as an index with 100. The smaller the index value and the smaller the index value, the smaller the peeling occurrence rate.

Method of evaluating uneven wear occurrence rate : Among the defective tires recovered from the general market, the number of tires in which the wear mode of the joint of the precure tread is significantly different from the wear mode other than the joint is produced at the same time. The failure rate was calculated by dividing the number of retreaded tires, and the values of the tire of the present invention, the comparative tire, and the conventional tire were compared.

It is expressed by an index with the uneven wear occurrence rate of the conventional tire as 100. The smaller the index value, the smaller the uneven wear occurrence rate. From Table 1, in the tire of the present invention and the comparative tire, all the retreaded tires have a structure in which the blocks are joined together at their joints, whereas the conventional tire is only 13%. Therefore, it can be seen that the peeling occurrence rate is significantly reduced in both the tire of the present invention and the comparative tire. Further, the tire of the present invention is provided with a sipe in the large block of the joint portion,
Since its rigidity is reduced to the level of a regular block, the uneven wear rate is the same as that of conventional tires.
It can be seen that in the comparative tire, uneven wear is more likely to occur because the rigidity of the large block at the joint is greater than that of the regular block.

[0022]

According to the present invention, a large block is arranged corresponding to the circumference of a stand tire in a block row provided on a belt-shaped precure tread, and cutting is performed at the position of this long block. By doing so, it is possible to always join the blocks of each block row without deteriorating the workability and improve the peeling resistance of the tread. Further, by providing a fine groove or sipe on the surface of the long block, the difference in rigidity between the block of the coupling portion and the block that is regularly arranged is reduced, so that the occurrence of uneven wear can be suppressed.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of a precure tread of the present invention.

FIG. 2 is a plan view showing a joint portion of a tread of a retreaded tire using the precure tread of FIG.

FIG. 3 is a plan view showing a joint portion of a tread of a conventional retreaded tire.

FIG. 4 is a plan view showing another example of the joining portion of the tread of the conventional retreaded tire.

5A is a sectional view taken along line XX of FIG. 3 and FIG. 4, FIG. 5B is a sectional view taken along line YY of FIG. 3, and FIG.
It is a Z sectional view.

FIG. 6 is a plan view of a conventional precure tread.

[Explanation of symbols]

1 Main Groove 2 Sub Groove 3 Block 30 Large Block 4 Sipe S Joint A, B, C, D, E Block Row

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[Procedure amendment]

[Submission date] April 2, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

It is represented by an index with the uneven wear occurrence rate of the conventional tire as 100. The smaller the index value, the smaller the uneven wear occurrence rate. From Table 1, in the tire of the present invention and the comparative tire, the completely rehabilitated tire has a structure in which the blocks are joined together at their joints, whereas the conventional tire is only 13%. Therefore, it can be seen that the peeling occurrence rates of the tire of the present invention and the comparative tire are significantly reduced. Also, subordinate
Conventional tires have a regular block size at the joint.
Is often less than or equal to
If the rigidity of the rack is equal to or less than the rigidity of the regular block,
Since there are many cases, uneven wear is likely to occur. Also compare
In the tire, the rigidity of the large block at the joint is normal.
Since it is much larger, uneven wear is likely to occur. On the other hand, in the tire of the present invention , a shallow groove or a type is provided on the surface of the large block at the joint to reduce the rigidity thereof to the level of a regular block. Conventional tire and comparison tie
It can be seen that it is lower than any of the above .

Claims (2)

[Claims] 1. A pre-cure tread in which a plurality of block rows arranged along the longitudinal direction are provided on the surface of a belt-shaped vulcanized rubber plate, wherein the plurality of the pre-cure treads are provided at a position corresponding to the circumferential length of a base tire. While arranging long blocks having a block length larger than the maximum block in the blocks regularly arranged in each block column side by side,
A pre-cure tread for rehabilitation in which shallow grooves or sipes are provided on the surface of the long block. 2. A block-shaped vulcanized rubber plate is provided with a plurality of block rows arranged along the longitudinal direction on the surface thereof, and the block length of each block row is larger than the largest block among the blocks regularly arranged. While arranging large large blocks side by side, a precure tread provided with shallow grooves or sipes on the surface of the large blocks is cut at an intermediate position of the large blocks corresponding to the circumferential length of the base tire, and the base tire is A pneumatic retreaded tire wound around the outer periphery of the above and butt-joined with the cut end faces of all the block rows.