JP2012040720A - Precured tread and retread tire using precured tread - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a precured tread which can improve the durability of a tire without impairing the aesthetic outside appearance of the tire and suppress the manufacturing cost; and a retread tire using the precured tread.SOLUTION: The precured tread 4 is stuck onto a base tire 2 along the circumferential direction of the base tire 2, and is made of a strip-shaped member including strip-shaped vulcanized rubber whose ends in the circumferential direction are stuck to each other via cushion rubber 3 when the precured tread is stuck. The length of the precured tread 4 in the circumferential direction is shorter than the whole length of the base tire 2 by the thickness of the cushion rubber 3 interposed between the ends in the circumferential direction of the precured tread 4. Further, the retread tire 1 using the precured tread 4 is provided.

Description

  The present invention is a pre-curing comprising a belt-shaped member including a belt-shaped vulcanized rubber that is bonded along the circumferential direction of the tire and is bonded to the longitudinal ends on the tire. The present invention relates to a tread and a retreaded tire using such a precure tread, and is intended to improve the durability of the tire and suppress the manufacturing cost without impairing the aesthetic appearance of the tire.

  Rehabilitated tires are widely known as tire recycling. Rehabilitated tires are tires obtained by removing the tread or tread and part of the belt layer from the used tires, and the tread part is replaced with a new material. And in the manufacturing method of a retread tire, a belt-like member containing rubber is previously patterned and vulcanized with a long mold to form a precure tread, and this precure tread is applied to the base tire at a relatively low temperature. There is a method of vulcanizing and bonding at a low pressure state on the bonding surface (see, for example, Patent Document 1).

  When the precure tread is affixed on the base tire, the precure tread composed of a belt-like member is attached along the base tire, and the circumferential ends thereof are brought into contact with each other for pasting. At this time, a cushion rubber is disposed between the base tire and the precure tread from the viewpoint of advantageously ensuring the adhesion between the two. Also, cushion rubber is disposed between the circumferential ends of the base tires, and both ends are bonded.

JP-A-10-119054

  For example, when pasting a precure tread on a base tire, a precure tread having a circumferential length larger than the entire circumference of the base tire is pasted, and the excess part of the precure tread is cut and removed. Then, the circumferential ends are brought into contact with each other and bonded together. Alternatively, a pre-cured tread having a predetermined circumferential length is prepared in advance and pasted on a base tire, and the circumferential ends thereof are brought into contact with each other and pasted together.

  However, in any case, no consideration is given to the thickness of the cushion rubber disposed between the circumferential ends of the precure tread. In actual application, the circumferential end of the precure tread is not considered. In some cases, a sufficient distance between them is not ensured, and the cushion rubber protrudes greatly outward in the radial direction, and the aesthetic appearance may be impaired. Further, through the process of cutting and removing the excess portion of the precure tread as described above, an error is likely to occur in the circumferential length of the precure tread. In some cases, it becomes longer than the entire circumference, and the pasting fails and the productivity is lowered. Furthermore, since retreaded tires are advantageous to consumers in that the manufacturing costs can be reduced compared to general new tires, there is a strong demand for reducing the manufacturing costs. Furthermore, retreaded tires are always required to be further improved in durability because of the demand for durability equivalent to that of new tires.

  Accordingly, an object of the present invention is to improve the durability of the tire and reduce the manufacturing cost without impairing the aesthetic appearance of the tire as described above, and the precured tread. The object is to provide a retreaded tire using cure tread.

  In order to achieve the above object, the precure tread of the present invention is affixed along the circumferential direction of the base tire on the base tire, and cushion edges are attached to the circumferential ends at the time of the base tire. A belt-shaped precured tread that is interposed and bonded, and the circumferential length of the precure tread is the cushion rubber interposed between the circumferential ends of the precure tread with respect to the entire circumferential length of the base tire. It is characterized by being short by the thickness.

  Further, it is preferable that at least one groove is provided on the surface of the tire on the ground contact surface side, and at least a part of the circumferential end of the belt-like member is located on a flat portion of the groove bottom of the groove. At this time, the circumferential end of the belt-shaped member extends from the one precure tread end to the other precure tread end along the groove bottom of the groove when the circumferential ends of the strip member are bonded together. It is preferable to be located. Moreover, it is preferable that the connection part between the groove bottom of a groove | channel and a groove wall has a curvature. Here, the “flat” groove bottom refers to a portion of the groove bottom having a planar shape perpendicular to the tire radial direction.

  And the retread tire of this invention uses the precure tread provided with the above-mentioned characteristic.

According to the present invention, by optimizing the tread shape of the precure tread and its circumferential end position, the durability of the tire is improved and the manufacturing cost is suppressed without impairing the aesthetic appearance of the tire. It has become possible to provide a precure tread that can be made and a retread tire using such a precure tread.

(A) is a partial top view of the retreaded tire which affixed the precure tread according to this invention on the base tire, (b) is the II sectional view taken on the line shown to (a). It is sectional drawing of a part of other precure tread according to this invention. It is a top view of a part of the retreaded tire which affixed the other precure tread according to this invention on the base tire.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Fig.1 (a) is a top view of a part of the retread tire which stuck the precure tread according to this invention on a base tire, FIG.1 (b) is the II sectional view taken on the line shown to Fig.1 (a). It is. FIG. 2 is a cross-sectional view of a portion of another precure tread according to the present invention. FIG. 3 is a plan view of a part of a retread tire in which another precure tread according to the present invention is pasted on a base tire.

  A retread tire 1 shown in FIGS. 1 (a) and 1 (b) has a belt-like shape in which a cushion rubber 3 is stuck on a tread portion region of a base tire 2 and then a belt-like vulcanized rubber is put on the cushion rubber 3. It is comprised by affixing the precure tread 4 which consists of a member. The precure tread 4 is affixed in the circumferential direction on the base tire 2 via the cushion rubber 3. At this time, the cushion rubber 3 is also disposed between the circumferential ends 5 of the precure tread 4. The circumferential ends 5 are bonded together. The precure tread 4 has a circumferential length that is shorter than the total circumferential length of the base tire 2 by the thickness of the cushion rubber 3 interposed between the circumferential ends of the precure tread 4. Is used. For this reason, when the precure tread 4 is affixed on the base tire 2, the cushion rubber 3 becomes insufficient in thickness, so that both ends of the precure tread 4 are not sufficiently bonded and the durability is lowered. Or, if the cushion rubber 3 is excessively thick, the cushion rubber 3 does not bulge outward and the aesthetic appearance is not impaired.

  Further, a plurality of grooves 6 extending in the tire circumferential direction and the tire width direction are provided on the surface on the tire contact surface side, and the groove bottom 7 of the groove 6 is flat. And it is preferable to comprise the precure tread 4 so that the cushion rubber 3 may be located in the flat part of the groove bottom 7 of the groove | channel 6 from a viewpoint of preventing the fall of the aesthetic appearance by the swelling of cushion rubber. Further, by bonding the precure tread 4 so that the circumferential end 5 is positioned on the flat portion of the groove bottom 7 of the groove 6, the circumferential ends 5 of the precure tread 4 are bonded without any step. As a result, the occurrence of cracks in the groove bottom 7 due to the concentration of stress on the step is suppressed, and the crack resistance of the retread tire 1 is improved, so that the durability is improved. Moreover, since the precure tread ends are bonded to each other at an appropriate length, the stone biting prevention performance is improved, and an effect synergistically with the improvement in crack resistance is achieved, thereby improving the durability. Further, by arranging the cushion rubber 3 along the groove bottom 7, the cushion rubber 3 does not protrude to the tread surface, and the length of the cushion rubber 3 in the tire radial direction is reduced as a whole. The amount can be reduced. Thereby, the weight reduction and cost reduction of the retread tire 1 are achieved. Further, since the cushion rubber 3 does not protrude to the tread surface, the aesthetic appearance is improved. Furthermore, since the change in the ground contact pressure of the block due to the cushion rubber 3 projecting to the tread surface can be suppressed, uneven wear resistance is improved.

  From the viewpoint of effectively exhibiting the above-described effects, the circumferential end 5 of the precure tread 4 extends from the end of one precure tread along the groove bottom 7 of the groove 6 as shown in FIG. It is preferable to be located extending to the end of the precure tread.

  Furthermore, since the thickness of the cushion rubber 3 disposed between the circumferential ends 5 of the precure tread 4 is 0.5 to 1.0 mm, the groove width at the groove bottom 7 of the groove 6 is 1. It is preferably 0 to 1.5 mm. This is because by making the flat part wider than the thickness of the cushion rubber, it becomes possible to absorb some errors in the cutting work, improving workability and reducing the defective rate of the product tire. It is because it reduces.

  In addition, as shown in FIG. 2, it is preferable that the connecting portion 9 between the groove bottom 7 and the groove wall 8 of the groove 6 has a curvature. When the connecting part 9 does not have a curvature, stress due to rubber deformation is excessively concentrated on the connecting part during rolling of the tire load, and the connecting part 9 may become a starting point of the crack. Therefore, it is preferable that the connecting portion has a curvature from the viewpoint of improving the crack resistance by dispersing the stress applied to the connecting portion 9. In addition, it is preferable that the curvature radius of the connection part 9 shall be 2.0 mm or more from a viewpoint of disperse | distributing the stress loaded to the connection part 9 appropriately, and improving crack resistance. This is because, when the radius of curvature of the connecting portion 9 is less than 2.0 mm, there is an increased possibility of cracks due to distortion in the connecting portion 9, so that the precure tread 1 is easily peeled from the base tire 2. .

  The above description shows only a part of the embodiment of the present invention, and these configurations can be combined alternately or various changes can be made without departing from the gist of the present invention.

  Next, a retread tire (Example tire 1) in which the precure tread of the present invention shown in FIG. 1 is attached to a base tire and a retread tire in which the precure tread according to the invention shown in FIG. Example tire 2) and Conventional tire 1 and Conventional tire each having the same structure as Example tires 1 and 2 except that the circumferential length of the precure tread is not shortened by the thickness of the cushion rubber. The example tire 2 was prototyped as a pneumatic tire having a tire size of 11R22.5, and various evaluations were performed, which will be described below.

  Crack resistance of the retreaded tire is determined by attaching each test tire to a rim of size 8.25 to form a tire wheel, applying an air pressure of 700 kPa (relative pressure) to the tire wheel, a tire load load of 2500 km, and a running speed of 60 km / The vehicle is run on a drum test machine for 20,000 km under the conditions of h, the tire after running is visually observed, the presence or absence of peeling of the pre-cured tread is confirmed, and the peeling appearance rate for each groove width ratio is obtained. (Roughly good). The results are shown in Table 1.

  In addition, the stone biting prevention performance of the retreaded tire was evaluated on a scale of 5 based on the number of stones and gravel in the groove after counting about 80000 km on the test road and counting the number of stones and gravel in the groove (large Moderate). The results are shown in Table 1.

  Furthermore, the aesthetic appearance was visually checked on the appearance of the tire, and was evaluated on a five-point scale (good level). The results are shown in Table 1.

  As is clear from the results in Table 1, the tires 1 and 2 of the example had improved durability and improved aesthetic appearance as compared with the conventional tires 1 and 2. In particular, in the example tire 2, the aesthetic appearance was improved.

  As apparent from the above invention, by improving the tread shape of the precure tread and the circumferential end position thereof, the durability of the tire is improved without impairing the aesthetic appearance of the tire, and It has become possible to provide a precure tread capable of suppressing production costs, a method for producing a retread tire using the precure tread, and a retread tire.

DESCRIPTION OF SYMBOLS 1 Rehabilitation tire 2 stand tires 3 Cushion rubber 4 Precure tread 5 Precure tread circumferential end 6 Groove 7 Groove bottom 8 Groove wall 9 Connection part

Claims (5)

In the belt-shaped pre-cured tread that is pasted along the circumferential direction of the base tire on the base tire and pasted with the cushion rubber interposed between the circumferential ends during the attachment,
The precured tread is characterized in that the circumferential length of the precure tread is shorter than the entire circumferential length of the base tire by the thickness of the cushion rubber interposed between the circumferential ends of the precure tread.   2. The tire according to claim 1, further comprising at least one groove on a surface on a ground contact surface side of the tire, wherein at least a part of a circumferential end of the belt-like member is located on a flat portion of a groove bottom of the groove. Precure tread.   The circumferential end of the band-shaped member extends from one precure tread end to the other precure tread end along the groove bottom of the groove when the circumferential ends of the band-shaped member are bonded together. The precure tread according to claim 2, which is located.   The precure tread according to claim 2 or 3, wherein the connecting portion between the groove bottom and the groove wall of the groove has a curvature.   A retread tire using the precure tread according to any one of claims 1 to 4.