JP2007076269A - Vulcanizing apparatus for retreaded tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vulcanizing apparatus for retreaded tire capable of enhancing tire durability in spite of a simple constitution. <P>SOLUTION: In the vulcanizing apparatus for the retreaded tire constituted by providing a bead ring 2c for surrounding the bead part of a tire 1 to be processed to the inner diameter part of a mold main body, which houses the tire 1 to be processed, and providing a vulcanizing bladder 3 expanded and contracted toward the inside of the tire 1 to be processed on the inner diametric side of the bead ring 2c, the bead ring 2c is formed into a hollow structure having a cavity part 4 therein. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a vulcanized apparatus for retreaded tires, and more particularly to a vulcanized apparatus for retreaded tires that can improve the durability of the retreaded tire.

  As tire recycling products, retread tires in which the tread is removed from used old tires as a base tire and only the tread is replaced with a new rubber material are widely known. Such tires can be manufactured by attaching unvulcanized tread rubber to the outer periphery of the base tire and vulcanizing it in a vulcanization mold in the same way as a normal new tire (remolding method) A method in which a vulcanized tread rubber is pasted with an unvulcanized cushion rubber interposed therebetween and then vulcanized in a vulcanizing can to vulcanize and bond the base tire and the tread rubber (precure method) (for example, And Patent Documents 1 and 2).

In the case of manufacturing by the former remolding method, the rubber of the base tire is heated again in the vulcanization mold, so that the rubber constituting the bead portion of the base tire is mainly transmitted from the bead ring of the vulcanization mold. There is a problem that the tire durability deteriorates due to heat deterioration during vulcanization. As a countermeasure, conventionally, an attempt has been made to adjust and control the temperature distribution of each part constituting the vulcanization mold, but it has been difficult to adopt because of high cost.
JP-A-7-195572 JP-A-9-207241

  An object of the present invention is to eliminate problems caused by thermal degradation when a retreaded tire is manufactured in a vulcanizing mold, and vulcanize a retreaded tire that can improve tire durability while having a simple configuration. Relates to the device.

  The vulcanization mold for a retread tire according to the present invention that achieves the above object is provided with a bead ring surrounding the bead portion of the processed tire on an inner diameter portion of a mold main body that accommodates the processed tire. In a retreaded tire vulcanizing apparatus provided with a vulcanizing bladder that expands and contracts toward the inside of the processed tire on the inner diameter side, the bead ring is formed in a hollow structure having a hollow portion therein. To do.

  According to the present invention, since the bead ring provided in the inner diameter portion of the mold body is formed in the hollow structure having the hollow portion, the amount of heat conduction to the bead ring during vulcanization is reduced, and the temperature of the bead ring is reduced. Therefore, the tire durability can be improved by preventing rubber deterioration of the bead portion.

Hereinafter, the configuration of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a vulcanized tire (hereinafter simply referred to as a “processed tire”) in which an unvulcanized tread rubber is attached to the outer periphery of a base tire using a vulcanizing apparatus for a corrected tire according to an embodiment of the present invention. It is a half sectional view showing the state.

  In FIG. 1, a vulcanizing apparatus for a corrected tire includes a sectional type vulcanizing mold 2 for housing a processed tire 1, a gold comprising a sector 2a for forming a tread portion and a side plate 2b for forming a sidewall portion. A vulcanization that includes a die body and a bead ring 2c surrounding the bead portion of the processed tire 1 provided on the inner diameter portion thereof, and expands and contracts toward the inner side of the processed tire 1 on the inner diameter side of the bead ring 2c. A bladder 3 is arranged. The bead ring 2c is formed in a hollow structure having a hollow portion 4 therein.

  By making the bead ring 2c into a hollow structure having the hollow portion 4, the amount of heat conduction to the bead ring 2c during vulcanization is reduced, and an increase in the temperature of the bead ring 2c is suppressed. The heat deterioration of the rubber in the bead portion is prevented, and the decrease in tire durability can be suppressed.

  In the present invention, the shape of the hollow portion 4 in the cross section of the bead ring 2c is not limited to a quadrangle (trapezoid) as shown in the figure, and can be formed into an arbitrary shape such as a circle or an ellipse. Is formed continuously over the entire circumference of the bead ring 2c. The volume occupied by the hollow portion 4 in the bead ring 2c is preferably as large as possible in order to maximize the effect of reducing the amount of heat conduction. However, if the volume occupied by the hollow portion 4 is increased too much, the bead ring 2c may be broken by the internal pressure received from the vulcanization bladder 3 during vulcanization. Therefore, the wall thickness of the bead ring 2c can withstand this internal pressure. Need to be set.

  The cavity 4 formed inside the bead ring 2c may be in a state of being filled only with air, but is preferably evacuated or filled with a heat insulating material. Although it does not specifically limit as a heat insulating material, Glass wool, a silica, etc. are mentioned. Thereby, the heat conduction amount to the bead ring 2c at the time of vulcanization can be further reduced, and the thermal deterioration of the rubber in the bead portion of the processed tire 1 can be reliably prevented.

  Furthermore, a cooling medium such as water may be forcibly circulated in the cavity 4 formed inside the bead ring 2c. Although it does not specifically limit as a cooling medium, It is good to keep the temperature at 40-80 degreeC, Preferably it is 50-70 degreeC. If the temperature is lower than 40 ° C, it becomes difficult to maintain the temperature of the sector 2a at a desired vulcanization temperature, which causes the quality of the corrected tire to deteriorate. If the temperature exceeds 80 ° C, the temperature of the bead ring 2c increases excessively and the bead portion The effect of preventing heat deterioration of rubber is not obtained.

  Further, the vulcanization bladder 3 is set so that the thickness of the portion corresponding to the inner wall surface of the bead ring 2c is larger than the thickness of the portion corresponding to the mold body (sector 2a and side plate 2b in FIG. 1). Good. Thereby, it becomes possible to suppress the amount of heat conduction from the vulcanization bladder 3 and to suppress the deterioration of the inner rubber of the bead portion.

  In addition, the division | segmentation form of the vulcanization mold 2 in this invention and the structure of a metal mold | die main body are not restricted to embodiment mentioned above, In addition to the case where the division | segmentation form is made into a sectional type as shown in FIG. A split mold may be used, and the mold body excluding the bead ring 2c may be composed of three or more parts.

  As described above, the vulcanizing device for a rectified tire according to the present invention is formed by forming a bead ring constituting a vulcanization mold of a retread tire in a hollow structure so that the rubber in the bead portion of the vulcanized tire after vulcanization is formed. It prevents thermal deterioration and improves tire durability. Since it has a simple configuration, it is widely used as a vulcanizing apparatus for vulcanizing a corrected tire by a remolding method.

  All forms except for the presence or absence of the cavity in the bead ring are made common as shown in FIG. 1, and a conventional device (conventional example) in which the cavity is not formed and a book in which the cavity is formed and filled with air. Invention device (Example 1), Invention device (Example 2) in a vacuum, Invention device (Example 3) filled with glass wool, Invention device (Forced circulation) of 60 ° C. cooling water Example 4) was prepared respectively. Using these five types of vulcanizers, retreaded tires of size 11R22.5 were produced.

  About five types of retreaded tires manufactured by the above, when tire durability was evaluated by the following method, the result described in Table 1 was obtained.

[Evaluation of tire durability]
Each tire is filled with air pressure 700 kPa and mounted on a rim (size: 22.5 × 8.25), and a load of 26.73 kN is applied at a speed of 50 km / h with a drum type endurance tester. The vehicle was run and the distance traveled until the tire failed was measured. The results are shown in Table 1 as an index with the measured value of the retreaded tire vulcanized by a conventional apparatus as 100. It shows that durability is excellent, so that a numerical value is large.

  From the results shown in Table 1, the retreaded tire vulcanized by the present invention device (Examples 1 to 4) in which the hollow portion is formed in the bead ring is vulcanized by the conventional device (conventional example) in which the cavity portion is not formed. It can be seen that the durability is improved as compared with the tire.

It is a half sectional view showing the state where the processed tire is vulcanized using the vulcanizing device for the corrected tire according to the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tire to be processed 2 Vulcanization mold 2a Sector 2b Side plate 2c Bead ring 3 Vulcanization bladder 4 Cavity

Claims (7)

A bead ring that surrounds the bead portion of the processed tire is provided in an inner diameter portion of a mold main body that accommodates the processed tire, and vulcanized to expand and contract toward the inner side of the processed tire on the inner diameter side of the bead ring. In vulcanized equipment for retreaded tires with bladders,
A vulcanized apparatus for retread tires in which the bead ring is formed in a hollow structure having a hollow portion therein.   The vulcanized apparatus for retread tires according to claim 1, wherein the hollow portion is evacuated.   The vulcanized apparatus for retread tires according to claim 1, wherein the hollow portion is filled with a heat insulating material.   The vulcanized tire vulcanizing apparatus according to claim 1, wherein a cooling medium is forcibly circulated in the hollow portion.   The vulcanized apparatus for retreaded tires according to claim 4, wherein the temperature of the cooling medium is maintained at 40 to 80 ° C.   The vulcanizing apparatus for a corrected tire according to any one of claims 1 to 5, wherein a thickness of a portion corresponding to the inner wall surface of the bead ring of the vulcanization bladder is made thicker than a portion corresponding to the mold body. A vulcanized method for retreaded tires, wherein the tire to be processed is vulcanized using the vulcanizing apparatus according to any one of claims 1 to 6.

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