JP2005193853A - Pneumatic tire for heavy load and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pneumatic tire for a heavy load and a manufacturing method therefor which enables extension of an abrasion life over a long period of time while controlling catch of gravels. <P>SOLUTION: A precure tread C of the pneumatic tire 1 for the heavy load, on whose surface grooves are formed, is integrally winded around the perimeter of a base tire B having grooves at its tread part 2. Then the manufacturing method for the pneumatic tire for the heavy load is that the precure tread C is molded, and the back side of the precure tread C is integrally winded and bonded with the perimeter of the base tire B. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heavy-duty pneumatic tire and a method for manufacturing the same, and more particularly to a heavy-duty pneumatic tire capable of extending the wear life while suppressing the occurrence of stone biting and a method for manufacturing the same.

  Among heavy duty pneumatic tires, the improvement of wear resistance is the most important requirement especially for tires for industrial vehicles. From such a user request, the groove depth D formed on the tread surface tends to be deeper as illustrated in FIG. However, the tire T having a deep groove on the tread surface makes it difficult for the stones caught in the deep grooves when traveling on gravel roads, etc., to spread the deep grooves and cause cracks at the bottom of the tires. Has a problem of causing damage (cut burst failure).

  As a countermeasure against such a problem, many proposals have been made so far to prevent stone biting by devising the shape of the groove wall and the groove bottom (see Patent Document 1). However, in these proposals, the effect could hardly be exhibited particularly as a measure for preventing stone biting of the tire of the ultra deep groove type.

In addition, instead of such measures, there are attempts to increase the width of the groove or reduce the depth of the groove to make it difficult for stone biting to occur. Did not become.
JP 2003-72320 A

  An object of the present invention is to solve such a conventional problem, and to provide a heavy duty pneumatic tire capable of extending the wear life while suppressing the occurrence of stone biting, and a method for manufacturing the same. It is in.

  In order to achieve the above object, a heavy-duty pneumatic tire according to the present invention is characterized in that a precure tread having a groove formed on the surface is wound and integrated on the outer periphery of a base tire having a groove in a tread portion. .

  Further, the method for manufacturing a heavy duty pneumatic tire of the present invention includes forming a precured tread having a groove on the surface, and winding the back surface of the precured tread around the outer periphery of a base tire having a groove in the tread portion. And integrated.

  In the heavy duty pneumatic tire of the present invention and the manufacturing method thereof, the precure tread having the groove formed on the outer periphery of the base tie having the groove in the tread portion is wound and integrated, so that the precure tread is completely worn out. A base tire having a groove in the tread portion will be exposed later, and the wear life can be greatly prolonged depending on the setting of the groove depth of the precure tread and the base tire.

  Furthermore, the groove of the precure tread and the groove of the base tire only need to achieve the desired wear life at the total depth, and each groove depth can be set to a depth at which stone biting is difficult to occur. This is advantageous in suppressing the occurrence.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. In each figure, the same components are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a partial plan view showing an example of a base tire constituting the heavy duty pneumatic tire of the present invention, and FIG. 2 is a cross-sectional view taken along the line XX showing the structure of the base tire of FIG.

  1 and 2, lug grooves 3a extending incline in the width direction from side to side across the tire equator line are formed in the tread portion 2 of the base tire B at intervals in the tire circumferential direction.

  As shown in FIG. 3, a precure tread C is wound around the outer periphery of the tread portion 2 of the base tire B, and these are integrated to form a heavy duty pneumatic tire 1. Here, the base tire B may be a new tire that has not yet traveled, or may be a tire after traveling a certain distance.

  The configuration of the tread pattern of the precure tread C is substantially the same as the configuration of the tread pattern of the base tire B shown in FIG. 1, and the lug groove 3b extending incline in the width direction from side to side across the tire equator line is provided. It is formed at intervals in the tire circumferential direction. Here, “substantially the same pattern configuration” means that the shape and arrangement of the grooves are the same, and the relative relationship between the width and the depth of each groove is the same.

  By configuring as described above, since the heavy duty pneumatic tire 1 of the present invention exposes the base tire B after the precured tread C is completely worn, the grooves of the precured tread C and the base tire B are exposed. The wear life can be greatly extended depending on the depth setting. Accordingly, the groove of the precure tread C and the groove of the base tire B need only to achieve a desired wear life with a total depth, and each groove depth can be set to a depth at which stone biting is difficult to occur. It is not necessary to form the groove depth of the cure red C and the base tire B in the deep groove from the beginning, which is advantageous in suppressing the occurrence of stone biting.

  In addition, by making the tread pattern of the base tire B and the tread pattern of the precure tread C substantially the same, the performance of the tire can always be kept constant until the wear life is reached.

  In the present invention, the heavy-duty pneumatic tire 1 includes a groove 3a having a maximum depth in the tread portion 2 of the base tire B and a groove 3b having a maximum depth in the precure tread C as shown in FIGS. It is preferable to integrate them so that the positions are shifted from each other. The displacement amount W of the grooves 3a and 3b with respect to the groove width direction is not less than 1/2 of the groove width GW of the groove 3a having the maximum depth in the tread portion 2 of the base tire B and not more than the groove width GW, as shown in FIG. It is good to.

  Thereby, even if stones enter the groove 3b, the position of the groove bottom of the groove 3b is protected by the surface of the tread portion 2 of the base tire B and prevents the stone from biting into the inner surface of the tread portion 2. If the amount of deviation W is less than 1/2 GW, the position of the groove bottom of the groove 3b matches the position of the groove 3a of the base tire B, so that the stone that has entered the groove 3b breaks the groove bottom of the groove 3b and becomes the groove 3a. At last, it becomes easy to bite into the inner surface of the tread portion 2. On the other hand, when the deviation amount W is greater than GW, the groove 3a of the base tire B is easily sag by the load during traveling, and the precure tread C at the position of the groove 3a is depressed toward the groove 3a, and the precure tread C A concave portion is formed on the surface, causing uneven wear.

  As shown in the embodiment described above, when the grooves having the maximum depth on the surface of the tread portion 2 and the precure tread C of the base tire B are the lug grooves 3a and 3b extending in the tire width direction, the base tire B In order to arrange the groove 3a and the groove 3b of the precure tread C so as to be displaced from each other, a precure tread C having a tread pattern having the same configuration as the tread pattern of the base tire B on the surface is prepared in advance. This is performed by laminating the groove 3b on the outer periphery of the base tire B so that the groove 3b does not overlap the groove 3a in the circumferential direction.

  On the other hand, when the grooves 3a and 3b having the maximum depth described above are circumferential grooves extending in the tire circumferential direction, the tread pattern of the precure tread 3 is previously set in the tire width direction with respect to the tread pattern of the base tire B. It is good to carry out by carrying out shaping | molding by shifting only the predetermined | prescribed deviation | shift amount, and bonding this to the outer periphery of the base tire 2. FIG.

  In the heavy duty pneumatic tire 1 of the present invention, the tire radial distance h from the groove bottom of the groove 3b having the maximum depth in the precure tread C to the surface of the tread portion 2 of the base tire B is 1 mm or more and 3 mm or less. Good. If the distance h is less than 1 mm, the sub-groove gauge of the groove 3b is too thin, and this portion is likely to be damaged when the precure tread C is manufactured and when attached to the outer peripheral surface of the base tire B. On the other hand, if the distance h exceeds 3 mm, the time until the surface of the tread portion 2 of the base tire B is exposed after the precure tread C is completely worn out becomes longer. This will lower the driving safety.

  The above-described heavy load pneumatic tire 1 of the present invention forms a precure tread C having a groove on the surface, and the back surface of the precure tread C is provided on the outer periphery of the tread portion 2 of the base tire B with an adhesive layer interposed therebetween. It is obtained by winding and bonding and integrating. Therefore, except that a tire having a groove in the tread portion 2 is used as the base tire B, the process is performed almost in the same process as the conventional method for manufacturing a retread tire.

  The manufacturing method of the present invention is characterized in that, in the step of forming the precure tread C, the configuration of the tread pattern formed on the surface of the precure tread C is substantially the same as the configuration of the tread pattern of the base tire B. There is to do.

  Furthermore, in the process of winding the precure tread C around the outer periphery of the base tire B and bonding them together, the groove 3b having the maximum depth in the precure tread C is the maximum depth in the tread portion 2 of the base tire B. The grooves 3a having the above are bonded so as to be shifted from each other within a range of 1/2 or more of the groove width GW and 3 or less of the groove width GW in the groove width direction.

  A conventional tire in which the lug groove in FIG. 7 is a deep groove (depth: 36 mm, width: 22 mm) with the tire size (1200R20 20PR LUG) and the tread pattern (FIG. 1) in common, and the base tire B in FIGS. 4 and 5 Ten tires of the present invention (deviation amount W = 11 mm, interval h = 1.8 mm) each having pre-cured tread C lug grooves 3a and 3b as shallow grooves (depth 18 mm, width 22 mm) were produced. In addition, the groove wall angle of the lug groove was set to 5 ° in common with the tire normal direction.

  Various tires were mounted on a 30-ton dump truck so as to be arranged as shown in FIG. 8, and were run on the steel works including gravel roads until the wear life was reached under the same conditions.

  As a result, three conventional tires had a cut burst failure at the bottom of the groove due to stone biting at the time of running about 40,000 km (remaining groove: about 50%), and the average wear life of the remaining seven tires was 95,000 km. It was the time of driving. On the other hand, in the tires of the present invention, no cut burst failure due to stone biting was observed in all tires until the end of wear, and the average wear life of 10 tires was at the time of running 103,000 km.

  From the results described above, in the heavy duty pneumatic tire of the present invention, the deep groove of the conventional tire has a two-stage configuration of the shallow groove of the base tire and the shallow groove of the precure tread, and the groove depth as a whole is equal. Thus, it can be seen that the wear life can be extended while suppressing the occurrence of stone biting.

It is a partial top view which shows an example of the base tire which comprises the heavy duty pneumatic tire of this invention. It is XX arrow sectional drawing which shows the structure of the base tire of FIG. It is explanatory drawing which shows the positional relationship of the base tire of FIG. 2, and the precure tread integrated with the outer periphery. 1 is a partial plan view of a heavy duty pneumatic tire according to an embodiment of the present invention. FIG. 5 is a cross-sectional view taken along the line YY in FIG. 4 illustrating the structure of the heavy duty pneumatic tire according to the embodiment of the present invention. It is ZZ arrow sectional drawing of FIG. It is sectional drawing which shows an example of the conventional deep groove type heavy load pneumatic tire. It is explanatory drawing which shows the mounting condition to the vehicle of the sample tire in an Example.

Explanation of symbols

B tires C Precure tread 1 Pneumatic tire for heavy loads 2 Tread portion of 3 tires 3a, 3b Lug groove

Claims (5)

  A heavy-duty pneumatic tire in which a precure tread having a groove formed on the surface thereof is wound and integrated on the outer periphery of a base tire having a groove in the tread portion.   The heavy-duty pneumatic tire according to claim 1, wherein the tread pattern of the base tire and the tread pattern of the precure tread are substantially the same.   The groove having the maximum depth of the pedestal tire and the groove having the maximum depth of the precure tread are in a positional relationship shifted from each other, and the shift amount in the groove width direction of the mutual groove is the amount of the groove on the pedestal tire side. The heavy-duty pneumatic tire according to claim 2, which is not less than ½ of the groove width and not more than the groove width.   4. The heavy load pneumatic according to claim 1, wherein a tire radial distance from a groove bottom of the groove having the maximum depth of the precure tread to a tread portion surface of the base tire is 1 mm or more and 3 mm or less. tire. A method for producing a heavy-duty pneumatic tire in which a precure tread having a groove on the surface is molded, and the back surface of the precure tread is wound around the outer periphery of a base tire having a groove in the tread portion and bonded together.

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