JP5708234B2 - Rehabilitated tire and manufacturing method thereof - Google Patents

Description

  The present invention relates to a retread tire using a base tire having a pair of belt edge cover layers embedded in a tread portion so as to cover an edge portion of a belt layer, and a manufacturing method thereof, and more particularly, a belt edge by buffing. The present invention relates to a retread tire and a method of manufacturing the retread tire that can sufficiently secure a volume of a new tread rubber layer after retreading while preventing damage to a cover layer and exhibit excellent durability.

  One of the manufacturing processes for retread tires is a buffing process. In this buffing process, the tread portion of a used pneumatic tire is polished along its crown shape (see, for example, Patent Document 1).

  However, when regenerating a pneumatic tire having a pair of belt edge cover layers embedded in the tread portion so as to cover the edge portion of the belt layer, if the belt edge cover layer is accidentally shaved in the buffing process, the belt The strength of the edge cover layer is lowered, and the durability of the retread tire is lowered.

  On the other hand, if the buff amount of the tread part is reduced in order to avoid damage to the belt edge cover layer, it is necessary to reduce the volume of a new tread rubber layer to be attached to the retread tire. It becomes difficult to secure a sufficient gauge for the new rubber part. And the gauge shortage of the new rubber part under a groove becomes a factor which reduces the durability of a retreaded tire.

JP 2011-25853 A

  An object of the present invention is to provide a retread tire capable of sufficiently securing a volume of a new tread rubber layer after retreading and exhibiting excellent durability while preventing damage to a belt edge cover layer due to buffing. It is in providing the manufacturing method.

  The retreaded tire of the present invention for achieving the above object includes a pair of belt edge cover layers embedded in the tread portion so as to cover the edge portion of the belt layer, and the tread portion is ground with respect to the base tire. In a retread tire with a tread rubber layer attached, convex portions projecting from a reference arc in a tire meridian section defining the buff surface at two locations in the tire width direction of the polished buff surface of the base tire are in the tire circumferential direction. The protrusions are selectively arranged at positions away from the buff ends and overlapping the belt edge cover layers.

  In addition, a method for manufacturing a retread tire according to the present invention for achieving the above object includes a tread portion of a used tire having a pair of belt edge cover layers embedded in the tread portion so as to cover the edge portion of the belt layer. In a method for manufacturing a retread tire in which a base tire is processed by polishing and a tread rubber layer is adhered to the base tire, the buffs are provided at two locations in the tire width direction of the polished buff surface of the base tire. The convex portions protruding from the reference arc in the tire meridian cross section defining the surface are formed so as to extend in the tire circumferential direction, and the convex portions are positioned away from the buff ends and overlap with the belt edge cover layers. It is characterized in that it is selectively arranged.

  In the present invention, when regenerating a pneumatic tire having a pair of belt edge cover layers embedded in the tread portion so as to cover the edge portion of the belt layer, each belt edge cover layer on the polished buff surface of the base tire By selectively forming the convex portion at a position overlapping with the belt edge cover layer can be prevented from being damaged by buffing, and the durability of the retreaded tire can be improved.

  Further, while the convex portion is selectively formed at a position overlapping with each belt edge cover layer of the polished buff surface of the base tire, a sufficient buff amount can be secured for other portions, so that the retread tire As a result, the volume of the new tread rubber layer to be attached to the can be increased as much as possible, and a sufficient gauge of the new rubber portion under the groove can be secured. This point also contributes to improving the durability of the retreaded tire.

  In the present invention, the following conditions are preferably satisfied in order to improve the durability of the retreaded tire. That is, when the region Ro is defined as 5% to 25% of the length in the tire width direction from the buff end to the buff surface, the convex portion is preferably disposed inside the region Ro. Further, when a region Ri is defined that is 10% to 20% of the length in the tire width direction from the buff end to the buff surface, it is preferable that the convex portion is disposed at least in the region Ri. Furthermore, it is preferable that the maximum protrusion amount of the convex portion from the reference arc of the buff surface is 1 mm to 4 mm. Moreover, it is preferable to form the convex portion so as to gradually increase from the reference arc of the buff surface. In this case, the convex portion has a top surface in the tire meridian cross section and a pair of inclined surfaces connected to the top surface, and the angles formed by the pair of inclined surfaces with respect to the reference arc of the buff surface are 20 ° to 45 °, respectively. It is preferable that

  Further, in a retreaded tire in which a tread rubber layer is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction, the main groove or the lug groove at a position overlapping the convex portion is buffed. It is preferable to make it shallower than the main groove or lug groove located on the tire equator side with respect to the convex portion in correspondence with the maximum protruding amount of the convex portion from the reference arc of the surface. In this case, the main groove or lug groove in the shoulder region at the position overlapping the convex portion can also ensure a sufficient gauge of the new rubber part under the groove, so the effect of improving the durability of the retreaded tire is achieved. Get higher. Rehabilitated tires are generally used for rear wheels and tend to produce center wear. However, if the main groove or lug groove in the shoulder region that overlaps the convex part is made relatively shallow, uniform wear is achieved. Can be achieved.

It is a perspective sectional view showing the important section of the retread tire which consists of an embodiment of the present invention. It is meridian sectional drawing which shows the principal part of the base tire for manufacturing the retreaded tire which consists of embodiment of this invention. It is sectional drawing which expands and shows the principal part of FIG. It is sectional drawing which expands and shows the principal part of FIG. It is sectional drawing which expands and shows the principal part of FIG.

  Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a retread tire according to an embodiment of the present invention, and FIGS.

  In FIG. 1, a base tire 1 is formed by polishing (buffing) a tread portion 11 of a used tire. This base tire 1 includes a carcass layer 12 mounted between a pair of bead portions. A plurality of belt layers 13 are embedded on the outer peripheral side of the carcass layer 12 in the tread portion 11. These belt layers 13 include a plurality of reinforcing cords inclined with respect to the tire circumferential direction, and are arranged so that the reinforcing cords cross each other between the layers. In the belt layer 13, the inclination angle of the reinforcing cord with respect to the tire circumferential direction is set, for example, in a range of 10 ° to 70 °. Further, a belt edge cover layer 14 having a two-layer structure is disposed on the outer peripheral side of the belt layer 13 so as to locally cover both edge portions of the belt layer 13 for the purpose of improving high-speed durability. The belt edge cover layer 14 includes a plurality of reinforcing cords arranged in the tire circumferential direction, and the angle of the reinforcing cords with respect to the tire circumferential direction is, for example, 5 ° or less.

  In addition, about this base tire 1, each dimension demonstrated below is measured in the state by which the tire was mounted | worn to the prescription | regulation rim, the prescription | regulation internal pressure was provided, and it was made no load. Here, the prescribed rim means “standard rim” prescribed in JATMA, “Design rim” prescribed in TRA, or “Measuring rim” prescribed in ETRTO. The specified internal pressure refers to the “maximum air pressure” specified by JATMA, the maximum value described in “TIRE LOAD LIMITS AT VARIOUS COLD INFLATION PRESSURE” specified by TRA, or “INFLATION PRESSURES” specified by ETRTO. However, in the case of tires for passenger cars, the specified internal pressure is 180 kPa. Moreover, although the dimension in the tire meridian cross section can be directly measured using a CT scanner or the like, for example, it is measured in a state in which a tire cut sample is applied to a tire contour measured by a laser profiler. It is also possible. As the laser profiler here, for example, a tire profile measuring device (manufactured by Matsuo Corporation) can be used.

  A new tread rubber layer 2 for rehabilitation is affixed on the outer periphery of the tread portion 11 with respect to the base tire 1 with the tread portion 11 polished. The tread rubber layer 2 is formed with a plurality of main grooves 21 extending in the tire circumferential direction and a plurality of lug grooves 22 and 23 extending in the tire width direction.

  In the retreaded tire, as shown in FIG. 2, convex portions 16 extending in the tire circumferential direction are formed at two locations in the tire width direction of the polished buff surface 15 of the base tire 1. The buff surface 15 has a radius of curvature R in the tire meridian cross section and is formed along a reference arc that protrudes outward in the tire radial direction, but the protrusion 16 protrudes from the reference arc that defines the buff surface 15. Yes. Each convex portion 16 is selectively disposed at a position away from the buff end 17 that is both ends of the buff surface 15 and overlapping with each belt edge cover layer 14.

  The retread tire includes a pair of belt edge cover layers 14 embedded in the tread portion 11 so as to cover the edge portion of the belt layer 13, but each belt edge cover of the polished buff surface 15 of the base tire 1. Since the convex portions 16 are selectively formed at positions overlapping with the layer 14, damage to the belt edge cover layer 14 due to buffing can be prevented, and durability thereof can be improved.

  Moreover, while the convex part 16 is selectively formed in the position which overlaps with each belt edge cover layer 14 of the polished buff surface 15 of the base tire 1, sufficient buff amount can be ensured about other parts. Therefore, the volume of the new tread rubber layer 2 to be attached to the retread tire can be increased as much as possible. Therefore, it is possible to sufficiently secure a gauge of a new rubber portion renewed below the main groove 21 and the lug groove 23 located on the tire equator CL side with respect to the convex portion 16. This point also contributes to improving the durability of the retreaded tire.

  In the retreaded tire described above, when a region Ro of 5% to 25% of the length L in the tire width direction of the buff surface 15 from the buff end 17 is defined, the convex portion 16 is preferably disposed inside the region Ro. If the convex portion 16 exists outside the region Ro in the tire width direction, the old rubber portion existing before the rehabilitation remains excessively even though the belt edge cover layer 14 is not present. Therefore, the durability of the retreaded tire is reduced. In addition, if the convex portion 16 exists on the inner side in the tire width direction from the region Ro, the convex portion 16 interferes with the main groove 21 and the lug groove 23, so that a gauge for a new rubber portion under the groove is secured. As a result, the durability of the retreaded tire decreases.

  Moreover, when the area | region Ri of 10%-20% of the length L of the buff surface 15 from the buff end 17 to the tire width direction is prescribed | regulated, the convex part 16 is good to arrange | position to the area | region Ri at least. If there is a portion where the convex portion 16 does not exist in the region Ri, the belt edge cover layer 14 may be damaged by buffing, and the reinforcing cord may be exposed.

  As shown in FIG. 3, the convex portion 16 is formed so as to be gradually higher from the reference arc of the buff surface 15, and a top surface 160 having a certain height in the tire meridian section, and the tire of the top surface 160 An inclined surface 161 extending inward in the tire width direction from the width direction inner end P1 and an inclined surface 162 extending outward in the tire width direction from the tire width direction outer end P2 of the top surface 160 are provided. In this case, the tire width direction inner side end P1 of the top surface 160 of the convex portion 16 is located at a position of 5 mm from the position Q1 to the tire width direction inner side with reference to the position Q1 of the belt edge cover layer 14 at the tire width direction inner end. It is desirable to arrange | position in the area | region X1 prescribed | regulated between the position of 2 mm to the tire width direction outer side from Q1. On the other hand, the outer end P2 in the tire width direction of the top surface 160 of the convex portion 16 is located at a position 5 mm from the position Q2 to the outer side in the tire width direction with respect to the position Q2 of the outer end in the tire width direction of the outermost belt layer 13. It is desirable to arrange | position in the area | region X2 prescribed | regulated between Q2 and the position of 2 mm inside a tire width direction. By arranging the inner end P1 and the outer end P2 of the top surface 160 of the convex portion 16 in the above range, the old rubber portion existing before the rehabilitation can be maximized while reliably preventing damage to the belt edge cover layer 14 due to buffing. Therefore, the durability of the retreaded tire can be improved.

  As shown in FIG. 4, the maximum protrusion amount H of the convex part 16 from the reference | standard circular arc of the buff surface 15 is good in it being 1 mm-4 mm. If the maximum protrusion amount H of the convex portion 16 is less than 1 mm, it is difficult to prevent damage to the belt edge cover layer 14 due to buffing. On the other hand, if it exceeds 4 mm, the remaining amount of the old rubber part existing before the retreading is increased, and the durability of the retreaded tire is lowered.

  Further, when the convex portion 16 has a top surface 160 and a pair of inclined surfaces 161 and 162 connected to the top surface 160 in the tire meridian cross section, the pair of inclined surfaces 161 and 162 correspond to the reference arc of the buff surface 15. The angles θ1 and θ2 formed are each 20 ° to 45 °, more preferably 25 ° to 40 °. When the angles θ1 and θ2 of the inclined surfaces 161 and 162 are less than 20 °, the remaining amount of the old rubber portion existing before the retreading is increased, so that the durability of the retreaded tire is lowered, and particularly the inclined surface 161 on the inner side in the tire width direction. If the angle θ1 is less than 20 °, the convex portion 16 easily interferes with the main groove 21 and the lug groove 23. Further, when the angles θ1 and θ2 of the inclined surfaces 161 and 162 exceed 45 °, air tends to remain at the interface between the base tire 1 and the new tread rubber layer 2 after retreading, and air remains at the interface. And separation on the rehabilitation surface is likely to occur. Note that the angles θ1 and θ2 of the inclined surfaces 161 and 162 are not necessarily the same. Moreover, the outline of the inclined surfaces 161 and 162 may be a straight line or a curved line.

  Further, when the tread rubber layer 2 is provided with the plurality of main grooves 21 extending in the tire circumferential direction and the plurality of lug grooves 22 and 23 extending in the tire width direction as described above, as shown in FIG. The lug groove 22 at a position overlapping with the lug groove 16 corresponds to the maximum protrusion amount H of the convex portion 16 from the reference arc of the buff surface 15, and is more than the lug groove 23 located on the tire equator CL side than the convex portion 16, respectively. It should be shallow. That is, the lug groove 22 on the convex part 16 is preferably raised. As a result, the lug groove 22 in the shoulder region located at the position overlapping the convex portion 16 can sufficiently secure a gauge of a new rubber portion renewed under the groove, thereby further improving the durability of the retreaded tire. Can be improved.

  However, the lug groove 22 in the shoulder region of the tread portion 11 is shallower than the lug groove 23 in the center region, but the groove depth D2 of the lug groove 22 is the groove depth D1 of the main groove 21 (the maximum groove depth in the tread portion 11). 80) or more of the above. Thereby, favorable drainage can be ensured. Further, when the main groove is present at a position overlapping the convex portion 16, the main groove may be shallow as in the case of the lug groove 22.

  When the above-mentioned retread tire is used for the rear wheel, there is a tendency to generate center wear. However, since the lug groove 22 in the shoulder region at the position overlapping the convex portion 16 is relatively shallow, uniform wear is achieved. Can be planned. That is, when the retread tire reaches the wear life, the lug groove 22 in the shoulder region and the main groove 21 and the lug groove 23 in the center region are worn at the same time.

  When manufacturing the retreaded tire described above, as shown in FIG. 2, first, the tread portion 11 of the used tire is polished to form the base tire 1. Convex portions 16 extending in the tire circumferential direction are formed at two locations in the tire width direction. Next, the tread rubber layer 2 including the main groove 21 and the lug grooves 22 and 23 is formed on the outer periphery of the tread portion 11 of the base tire 1. The tread rubber layer 2 may be formed by winding a precure tread around the outer periphery of the tread portion 11 of the base tire 1 via an adhesive rubber layer, or on the outer periphery of the tread portion 11 of the base tire 1. Alternatively, an unvulcanized rubber composition may be disposed on the surface and vulcanized in a state where a mold is pressed from the outside. In this manner, the rehabilitation work is completed by attaching the tread rubber layer 2 to the base tire 1.

  In rehabilitating used tires of tire size 205 / 85R16, the retread tires of the conventional example, comparative example 1 and examples 1 to 5 were obtained by changing the structure of the base tire as shown in Table 1.

  In Examples 1 to 5 and Comparative Example 1, convex portions are formed at two locations in the tire width direction of the polished buff surface of the base tire, and the position of the convex portion (relative to the length L of the buff surface in the tire width direction). The position from the buff end), the maximum protrusion amount H, and the angle θ1 and θ2 of the inclined surface of the convex portion are varied, and if necessary, the lug groove on the convex portion can be formed according to the maximum protrusion amount H of the convex portion. Raised the bottom. On the other hand, in the conventional example, no protrusion was formed on the buff surface of the base tire.

  For these test tires, the durability was evaluated by the following measurement method, and the results are also shown in Table 1.

durability:
Each test tire after retreading was assembled on a wheel with a rim size of 16 × 5.50, the air pressure was 600 kPa, and the drum surface had a smooth steel surface and a drum with a diameter of 1707 mm under the conditions specified in JIS D4230. Using a drum tester, the ambient temperature was controlled to 38 ± 3 ° C., the initial load was 8.82 kN (70% of the maximum load capacity of JATMA), the initial speed was 65 km / h, and the vehicle started to run at JIS D4230. After running under the prescribed conditions, the load was increased by 8% every 6 hours and the speed was increased by 5 km / h, and the distance traveled until the tire broke was measured. The evaluation results are shown as an index with the conventional example being 100. The larger the index value, the better the durability.

  As can be seen from Table 1, the durability of the tires of Examples 1 to 4 was improved in comparison with the conventional example. Moreover, in the tire of Comparative Example 1, since the convex part of the buff surface was at a position deviated from the belt edge cover layer, the effect of improving the durability was not seen.

1 tire 2 tread rubber layer 11 tread portion 12 carcass layer 13 belt layer 14 belt edge cover layer 15 buff surface 16 convex portion 17 buff end 21 main groove 22, 23 lug groove CL tire equator

Claims (14)

  A retread tire comprising a pair of belt edge cover layers embedded in a tread portion so as to cover an edge portion of the belt layer, and a tread rubber layer attached to a base tire having the tread portion polished, the base tire Convex portions protruding from the reference arc in the tire meridian cross section defining the buff surface are formed at two locations on the polished buff surface in the tire width direction so as to extend in the tire circumferential direction, and these convex portions are buffed. A retread tire characterized by being selectively disposed at a position away from the end and overlapping with each belt edge cover layer.   The said convex part has been arrange | positioned inside the said area | region Ro, when the area | region Ro of 5%-25% of the length of the said buff surface of the said buff surface in the tire width direction is prescribed | regulated. Rehabilitation tire.   3. The rehabilitation according to claim 2, wherein when the region Ri is defined as 10% to 20% of the length in the tire width direction of the buff surface from the buff end, the convex portion is disposed at least in the region Ri. tire.   The retreaded tire according to any one of claims 1 to 3, wherein a maximum protrusion amount of the convex portion from the reference arc of the buff surface is set to 1 mm to 4 mm.   The retread tire according to any one of claims 1 to 4, wherein the convex portion is formed so as to be gradually higher from the reference arc of the buff surface.   The convex portion has a top surface in the tire meridian cross section and a pair of inclined surfaces connected to the top surface, and the angle formed by the pair of inclined surfaces with respect to the reference arc of the buff surface is 20 ° to 45 °, respectively. The retreaded tire according to claim 5, wherein   In the retread tire in which the tread rubber layer is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction, the main groove or the lug groove at a position overlapping with the convex portion, 2. The main groove or lug groove located on the tire equator side than the convex portion is made shallower than the convex portion, corresponding to the maximum protruding amount of the convex portion from the reference arc of the buff surface. The rehabilitated tire according to any one of 6.   A tread portion of a used tire having a pair of belt edge cover layers embedded in the tread portion so as to cover the edge portion of the belt layer is polished to process a base tire, and the tread rubber layer is applied to the base tire. In the method for manufacturing a retread tire, the protrusions protruding from the reference arc in the tire meridian section defining the buff surface are provided at two locations in the tire width direction of the polished buff surface of the base tire. A method for producing a retread tire, characterized in that it is formed so as to extend in the direction, and these convex portions are selectively arranged at positions away from the buff end and overlapping each belt edge cover layer.   The said convex part has been arrange | positioned inside the said area | region Ro, when the area | region Ro of 5%-25% of the length of the buff surface of the said buff surface from the said buff end is prescribed | regulated. Method for manufacturing retreaded tires.   10. The rehabilitation according to claim 9, wherein when the region Ri is defined as 10% to 20% of the length in the tire width direction of the buff surface from the buff end, the convex portion is disposed at least in the region Ri. Tire manufacturing method.   The method for manufacturing a retread tire according to any one of claims 8 to 10, wherein a maximum protrusion amount of the convex portion from the reference arc of the buff surface is set to 1 mm to 4 mm.   The method for manufacturing a retread tire according to any one of claims 8 to 11, wherein the convex portion is formed so as to be gradually higher from the reference arc of the buff surface.   The convex portion has a top surface in the tire meridian cross section and a pair of inclined surfaces connected to the top surface, and the angle formed by the pair of inclined surfaces with respect to the reference arc of the buff surface is 20 ° to 45 °, respectively. The method for producing a retread tire according to claim 12, wherein   In the method of manufacturing a retread tire in which the tread rubber layer is provided with a plurality of main grooves extending in the tire circumferential direction and a plurality of lug grooves extending in the tire width direction, the main groove or lug at a position overlapping the convex portion. The groove is made shallower than the main groove or lug groove located on the tire equator side than the convex portion, corresponding to the maximum protrusion amount of the convex portion from the reference arc of the buff surface. The manufacturing method of the retreaded tire in any one of Claims 8-13.

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