JP6258137B2 - Rehabilitated tire manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a retread tire in which a precure tread is disposed on an outer peripheral surface of a base tire.

  A pneumatic tire basically has a structure in which a tread rubber in contact with a road surface is attached to a base tire. Since tread rubber wears as tires run for a long period of time, their useful life is limited. However, in the case of a base tire, it can often be used sufficiently even if the life of the tread rubber is over. For this reason, the worn tread rubber portion may be covered with a new tread rubber and used again as a retread tire. Recycled tires are often used as tires for automobiles, particularly heavy duty tires for trucks or buses, in order to reduce tire costs.

  In the production of retreaded tires, there is a broad classification: a remolding method in which unvulcanized tread rubber is affixed to the base tire, and a tread pattern is imparted to the tread rubber while being vulcanized in a mold. A vulcanized tread rubber (precured tread) with a slag is attached to the base tire to form a precured tread attaching base tire, which is attached to a rim-like body, and an annular vulcanizing envelope is attached. There are two types: a pre-cure system in which a precure tread attaching base tire is covered from above and vulcanized in a vulcanizing can.

  Among the two types of methods described above, the precure method does not require a large-scale vulcanization mold like the remolding method, and has an advantage in the manufacturing method such that a plurality of vulcanization can be performed simultaneously with a simple apparatus. Moreover, since the tires renewed by the precure method are formed by joining and integrating the tread rubber and the base tire using both vulcanized members, the tire obtained by the remolding method. It is easy to obtain a uniform tire as compared with. For this reason, compared with a tire rehabilitated by the remolding method, there is an advantage that uneven wear hardly occurs, wear resistance is excellent, and durability is increased.

  However, in the precure method, when the precure tread is affixed to the pedestal tire, it is difficult to align the precure tread with the pedestal tire, and depending on the technique of the operator, the center positions of both may be displaced.

  In Patent Document 1 below, in a retread tire in which a belt-shaped precure tread is wound through an adhesive rubber layer on a base tire whose tread portion is polished, a tire width direction of the tread portion where the base tire is polished A convex portion or a concave portion that extends in the tire circumferential direction at at least one location, and that engages with the convex portion or the concave portion of the base tire on the back surface portion located on the base tire side of the precure tread. Techniques for forming are described.

  Further, in Patent Document 2 below, when manufacturing a base tire constituting a retread tire, a buff surface is formed by scraping a tread portion of a used tire, and both ends of the buff surface in the width direction are tire diameters from the center in the width direction. A technique of cutting so as to be positioned higher in the direction is described.

JP 2011-245880 A JP 2010-173139 A

However, each of the above prior arts has the following problems. That is, in the technology described in Patent Document 1, the precure tread and the base tire are attached via an adhesive rubber layer, but the precure tread and the base tire have a concave-convex engagement portion. There is a high possibility that air is inevitably mixed between the precure tread and the adhesive rubber layer or between the base tire and the adhesive rubber layer. Since the mixed air is difficult to remove during vulcanization molding, there is a high possibility that air will be mixed into the rubber of the retread tire finally obtained. As a result, the uniformity of the obtained retreaded tire may be deteriorated. Furthermore, in the technique described in Patent Document 1, since the adhesive rubber layer interposed between the precure tread and the base tire is exposed, there is a tendency that the final appearance of the retread tire obtained is inferior. It was.

  In addition, the technique described in Patent Literature 2 is for suppressing the belt end portion located in the outermost layer of the tire from being buffed accidentally when manufacturing a base tire by buffing a used tire. Due to the technology, it is difficult to obtain the effect of facilitating the alignment of the precure tread with respect to the base tire. Furthermore, even in the technique described in Patent Document 2, since the adhesive rubber layer interposed between the precure tread and the base tire is exposed, there is a tendency that the final appearance of the retread tire obtained is inferior. It was.

  The present invention has been developed in view of the above circumstances, and provides a method for manufacturing a retread tire that is accurate in positioning of a precure tread with respect to a base tire, excellent in uniformity, and excellent in appearance. Objective.

  The above problems can be achieved by the following configuration. That is, the present invention is a method of manufacturing a retread tire in which a precure tread is disposed on an outer peripheral surface of a base tire, and the base tire includes a flat surface portion including a tire equator and the flat surface portions at both ends in the width direction. A method of manufacturing a retread tire, comprising a step of disposing the precure tread so as to fit between the convex portions of the base tire.

  According to the method for manufacturing a retread tire according to the present invention, since the precure tread is disposed so as to be fitted between the convex portions of the pedestal tire, the precure tread can be reliably fixed on the pedestal tire. Thereby, the alignment of the precure tread with respect to the base tire becomes accurate. For this reason, the uniformity of the retread tire finally obtained improves. In addition, the precure tread is disposed so as to be in contact with the flat surface portion of the pedestal tire, and the inner peripheral surface side of the precure tread is also a flat surface, and therefore there is no engagement portion such as an unevenness. For this reason, even if it is a case where the rubber layer for adhesion | attachment is interposed between a precure tread and a base tire, possibility that air will mix can be reduced. Further, even when an adhesive rubber layer is interposed between the precure tread and the pedestal tire, the adhesive rubber layer is covered by convex portions located at both ends in the width direction of the pedestal tire. For this reason, it is excellent in the external appearance of the retreaded tire finally manufactured. In the present invention, the precure tread may be disposed so as to be in direct contact with the flat surface portion of the base tire, and may be in contact with the flat surface portion of the base tire through an adhesive layer made of an adhesive rubber layer or the like. May be arranged.

  In the retreaded tire manufacturing method, the precure tread is preferably a ring-shaped precure tread. According to this configuration, the uniformity of the retread tire that is finally manufactured can be further improved, and the occurrence of a detachment failure of the precure tread can be suppressed.

  In the said retreaded tire manufacturing method, it is preferable that the height of the said convex part from the said flat surface part is 5-7 mm. According to such a configuration, it is possible to prevent the displacement of the precure tread with respect to the base tire more reliably. Furthermore, since the adhesive rubber layer can be more reliably covered by the convex portions located at both ends in the width direction of the base tire, the appearance of the finally manufactured retread tire can be further improved.

  The retreaded tire according to the present invention is manufactured by any one of the manufacturing methods described above. Such retreaded tires are excellent in appearance and uniformity.

The meridian cross-sectional view showing an example of a retread tire manufactured in the manufacturing method according to the present invention

  The retread tire manufactured in the manufacturing method according to the present invention will be described below with reference to the drawings. FIG. 1 is a meridian cross-sectional view showing an example of a retread tire manufactured by the manufacturing method according to the present invention.

  In FIG. 1, a base tire 1 is formed by buffing a tread portion of a used tire. In the retread tire according to the present embodiment, a precure tread 2 is disposed on the outer periphery of the tread portion via an adhesive rubber layer 3 with respect to the base tire 1 whose tread portion is buffed.

  The base tire 1 has a flat surface portion P1 including the tire equator C. In order to ensure adhesion between the base tire 1 and the precure tread 2, the relationship between the width W2 of the precure tread 2 and the overall width W of the base tire 1 on the tire tread is expressed as W2> 0.9W. It is preferable that W2 ≧ 0.95W.

  Furthermore, the base tire 1 has the convex part P2 which protruded from the flat surface part P1 on both sides of the width direction. The convex part P2 may extend continuously in the tire circumferential direction, or may extend intermittently in the tire circumferential direction. The position in the width direction of the convex portion P2 is preferably outside the range of 90% centered on the tire equator C when the total width W of the base tire 1 on the tire tread surface is 100%, and out of the range of 95%. More preferably. In order to surely prevent the displacement of the precure tread 2 with respect to the base tire 1 and to further improve the appearance of the retread tire to be finally produced, the height H1 of the convex portion P2 from the flat surface portion P1 is set to 3 It is preferable to set it as 10 mm, and it is more preferable to set it as 5-7 mm. From the same viewpoint, the height H1 of the convex portion P2 with respect to the height H2 of the precure tread 2 is preferably 0.1H2 ≦ H1 ≦ 0.5H2.

  As the precure tread, a flat plate precure tread produced by a method known to those skilled in the art may be used, or a ring precure tread may be used. However, in the present invention, when a ring-shaped precured tread is used, the uniformity of the retread tire to be finally produced is further improved, and the occurrence of peeling failure of the precured tread can be suppressed, which is preferable. . Even when a ring-shaped precure tread is used, the inner peripheral surface side is preferably formed into a flat surface.

  The method for producing the ring-shaped precure tread is not particularly limited, but preferably, after attaching the unvulcanized tread rubber to the ring-shaped dedicated core having a heating function, the vulcanization equipment is used to It is manufactured by a method of manufacturing a ring-shaped precure tread having a tread pattern formed on the outer peripheral surface side by heating and vulcanizing from both the outer peripheral surface side and the inner peripheral surface side while forming a tread pattern be able to. According to this manufacturing method, the vulcanization equipment used when manufacturing a new tire can be used as it is after pasting the unvulcanized tread rubber on the ring-shaped dedicated core. For this reason, since the new vulcanization molding mold only for a retreaded tire becomes unnecessary, the manufacturing cost of a retreaded tire can be reduced significantly.

  Moreover, in the said manufacturing method, the ring-shaped exclusive core which affixes unvulcanized tread rubber has a heating function, and it can heat from the inner peripheral surface side of unvulcanized tread rubber in a vulcanization process. Therefore, while forming a tread pattern on the outer peripheral surface side of the unvulcanized tread rubber, it is heated and vulcanized from both the outer peripheral surface side and the inner peripheral surface side, and the tread pattern is formed on the outer peripheral surface side. Precured tread can be produced. As a result, even when a ring-shaped precure tread is produced, the vulcanization time can be shortened.

  Furthermore, in the above manufacturing method, a ring-shaped precured tread having a tread pattern formed on the outer peripheral surface side is manufactured by pasting unvulcanized tread rubber on a ring-shaped dedicated core. It is possible to manufacture a retread tire excellent in the above.

  In such a manufacturing method, first, unvulcanized tread rubber is attached to a ring-shaped dedicated core having a heating function. The unvulcanized tread rubber may be pasted while being wound around a ring-shaped dedicated core by using one that has been extruded into a predetermined flat plate shape by an extruder. Alternatively, while rotating the ring-shaped dedicated core around the ring axis, the ribbon-shaped unvulcanized rubber is directly extruded from the discharge nozzle of the extruder onto the outer peripheral surface, and a predetermined shape is formed while being wound in layers on the dedicated core. You may shape | mold the unvulcanized tread rubber which has.

  The ring-shaped dedicated core used in the present invention has substantially the same shape as the base tire and has a heating function. The heating function is not particularly limited, and examples thereof include a built-in electric heater or a device using heated steam, inert gas, hot water, or the like. In the present invention, since the ring-shaped dedicated core has a heating function, the unvulcanized tread rubber can be heated and vulcanized also from the inner peripheral surface side. Thereby, when manufacturing a ring-shaped precure tread, vulcanization | cure time can be shortened significantly.

  Further, in the present invention, the unvulcanized tread rubber adhered in a ring shape is vulcanized to a dedicated core having substantially the same shape as the base tire. Substantially the same vulcanization equipment can be used.

  In the method for producing a precure tread according to the present invention, the vulcanization time and vulcanization temperature when vulcanizing the precure tread are considered in consideration of the tire shape and size of the retread tire to be finally produced. It can be set to any condition.

  A ring-shaped precured tread produced by the above production method is disposed by fitting it to the outer peripheral surface of the base tire, for example, via an adhesive rubber layer to form a precured tread pasting base tire, again, A retreaded tire can be produced by vulcanizing the precure tread attachment tire. The retreaded tire manufactured by the manufacturing method according to the present invention is excellent in appearance and uniformity.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
By buffing the used tire, a table having convex portions P2 extending continuously in the tire circumferential direction on both sides in the width direction and outside the range of 95% around the tire equator C. Tire 1 was manufactured (base tire 1 shown in FIG. 1). The width P1 of the convex portion P2 was set to 5 mm and the height H1 was set to 7 mm. Next, using a pair of flat plate vulcanization molds capable of sandwiching an unvulcanized tread rubber member formed into a belt shape, heating and vulcanization are performed under conditions of a vulcanization temperature of 160 ° C. and a vulcanization time of 20 minutes. By doing so, the flat plate-shaped pre-cured tread 2 (Pre-cured tread 2 shown in FIG. 1) was manufactured. H2 = 23.5 mm and W2 = 210 mm.

  The manufactured flat precure tread 2 is affixed while being wrapped around the base tire 1 via an adhesive rubber layer 3 known to those skilled in the art to form a precure tread affixing base tire, A retread tire (tire size 11R22.5) was produced by vulcanizing the cure tread pasting tire (vulcanization temperature 120 ° C., vulcanization time 300 minutes).

Example 2
After pasting unvulcanized tread rubber on a ring-shaped dedicated core with a heating function, using the new tire vulcanization equipment, forming the tread pattern on the outer peripheral surface side, the outer peripheral surface side and the inner peripheral surface side From both sides, a ring-shaped pre-cured tread 2 having a tread pattern formed on the outer peripheral surface side (precured as shown in FIG. 1) is heated and vulcanized at a vulcanization temperature of 160 ° C. and a vulcanization time of 20 minutes. Tread 2) was produced. H2 = 23.5 mm and W2 = 210 mm. A retread tire was produced in the same manner as in Example 1 except that this ring-shaped precure tread was used in place of the flat precure tread.

Comparative Example 1
A retread tire was manufactured in the same manner as in Example 1 except that a base tire that did not have a convex portion (the tire tread surface is composed entirely of a flat surface portion) was used as the base tire.

Comparative Example 2
As a pedestal tire, a pedestal tire that does not have a convex portion (the tire tread surface is composed entirely of a flat surface portion) is used, and a flat precure tread that extends in the width direction and extends to both ends in the width direction. A retreaded tire was produced in the same manner as in Example 1 except that a flat plate-shaped pre-cured tread having a notch (width of notch 2 mm, depth of notch 5 mm) was used.

Comparative Example 3
As a pedestal tire, a pedestal tire in which convex portions (convex portion width 2 mm, convex portion height 2 mm) extending continuously in the tire circumferential direction are formed on the tire equator, and as a flat precure tread, A retread tire was manufactured in the same manner as in Example 1 except that a flat precure tread having a concave portion that meshed with the convex portion of the base tire on the circumferential side was used.

Comparative Example 4
As a base tire, a base tire formed by cutting the tread part of a used tire to form a buff surface and scraping both ends in the width direction of the buff surface to be positioned higher in the tire radial direction than the center in the width direction is used. The retreaded tire was obtained by the same method as in Example 1 except that a flat precure tread having a shape corresponding to the tire tread side shape of the base tire on the inner peripheral surface side was used as the flat precure tread. Manufactured.

(Uniformity evaluation method for retreaded tires)
The uniformity of the finally manufactured retread tire was measured by measuring the LFV (lateral force balance) based on the test method defined in JIS-D4233. Specifically, the amount of variation in the lateral force generated when the tire was rotated while being pressed against the rotating drum was measured and evaluated by the reciprocal of the measured value. Evaluation means index evaluation with the result of Comparative Example 1 being 100, and the larger the value, the better the tire uniformity.

(Durability evaluation method for retreaded tires)
In addition, the durability of the finally manufactured retread tire was measured by performing a drum test described below.
Drum test: A drum tester having a 1700 mm diameter rotating drum made of steel with a smooth surface, with an ambient temperature of 38 ± 3 ° C., a tire internal pressure of 900 kPa, and a speed of 56 km / h, at 66% of the maximum load specified by JATMA. After running for 4 hours, then at 84% of the maximum load for 16 hours, at 101% of the maximum load for 24 hours, and further at 110% of the maximum load for 24 hours, the load increases by 10% every 12 hours. It was run until it occurred. The distance traveled until the failure occurs is shown in the table as an index with Comparative Example 1 as 100. The larger the index, the better the durability.

(Appearance evaluation method for retreaded tires)
Appearance was evaluated on a five-point scale by visually confirming the appearance of the tire. (The higher the number, the better)

  From the results described in Table 1, it can be seen that the retreaded tire manufactured by the manufacturing method according to Example 1-2 is excellent in uniformity and durability and excellent in appearance.

Claims (2)

A precured tread is a method of manufacturing a retreaded tire disposed on an outer peripheral surface of a base tire,
The pedestal tire has a flat surface portion including the tire equator and convex portions protruding from the flat surface portion at both ends in the width direction.
Look including the step of disposing so as to fit the precured tread between the projecting portion of said platform tire,
The height of the convex part from the flat surface part is 5 to 7 mm,
A method for manufacturing a retread tire, wherein a height H1 of the convex portion with respect to a height H2 of the precure tread is 0.1H2 ≦ H1 ≦ 0.5H2 .   The method for producing a retread tire according to claim 1, wherein the precure tread is a ring-shaped precure tread.

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