JP2016043668A - Production method of retreaded tire, and retreaded tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a production method of a retreaded tire capable of shortening a work time for a vulcanization treatment, and improving productivity, by reducing the number of steps in the vulcanization treatment of a retreaded tire, and by simplifying a facility.SOLUTION: In a production method of a retreaded tire, a precure tread-attached base tire formed by sticking a precure tread onto a crown part of a base tire through unvulcanized cushion rubber is subjected to heat treatment, to thereby vulcanize and bond the precure tread onto the base tire. In the production method of the retreaded tire, a heating medium is injected into a tube arranged separately from the precure tread on the tire radial direction outside, and disposed in a metal mold for covering the precure tread, and while pressing the precure tread to the tire radial direction inside by expanding the tube, the unvulcanized cushion rubber is heated from the precure tread side, to thereby perform heat treatment.SELECTED DRAWING: Figure 1

Description

  The present invention provides a precure tread to a base tire by vulcanizing a base tire with a precure tread formed by attaching a precure tread to the crown portion of the base tire via an unvulcanized cushion rubber. The present invention relates to a method for producing a retread tire that is vulcanized and bonded, and a retread tire.

  A pneumatic tire basically has a structure in which a tread in contact with a road surface is attached to a base tire. Since the tread wears as the tire runs for a long period of time, the service life is limited. However, with respect to the base tire, the tread can often be used sufficiently even after the end of its life. For this reason, the worn tread portion may be covered with a new tread 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, and a tread pattern is already provided, as well as a remolding method in which an unvulcanized tread is attached to a base tire and a tread pattern is imparted to the tread while being vulcanized in a mold. The precured tread is affixed to the base tire to form a base tire with a precured tread, and this is attached to the rim body, and an annular vulcanization envelope is placed over the base tire with the precured tread. In addition, there are two types of precure methods (described in, for example, Patent Document 1 below) in which a precure tread and a base tire are brought into close contact with each other by degassing the inside of the envelope and vulcanized in a vulcanization can. is there.

  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, the tires renewed by the precure method are formed by joining and integrating both members using vulcanized members for both the tread and the base tire. Compared to this, it is easy to obtain a uniform tire. 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.

JP 7-246665 A

  However, in the precure tread method, it is necessary to deaerate the inside of the envelope covering the pedestal tire with the precure tread in order to ensure the adhesion between the precure tread and the pedestal tire during vulcanization. Since it takes a lot of man-hours and time, the actual situation is that it often contributes to the deterioration of the productivity of retreaded tires. Furthermore, when using vulcanized cans, it is necessary to vulcanize multiple tires at once to improve productivity, leading to an increase in equipment size, and in the case of a small number of production, the production cost Contributed to the rise.

  The present invention has been made in view of the above circumstances, and by reducing the number of steps during vulcanization treatment of retreaded tires and simplifying equipment, the work time of vulcanization treatment is shortened and productivity is improved. An object of the present invention is to provide a method for producing a retread tire.

  The above object can be achieved by the following configuration. That is, the method for manufacturing a retread tire according to the present invention includes a pair of annular bead portions, a pair of sidewall portions extending outward in the tire radial direction from the bead portions, and a crown portion positioned between both sidewall portions. The pre-cured tread with the precure tread formed by attaching the precure tread to the crown portion of the pedestal tire via an unvulcanized cushion rubber is heat treated. A method of manufacturing a retreaded tire that is vulcanized and bonded to the precure, in which a heating medium is injected into a tube that is spaced apart from the precure tread in the tire radial direction and is disposed in a mold that covers the precure tread. As a result, the precure tray is inflated while inflating the tube and pressing the precure tread inward in the tire radial direction. By heating the unvulcanized cushion rubber from de side, wherein the heat treatment is carried out.

  In the method of covering the annular vulcanization envelope from the base tire with the precure tread and degassing the inside of the envelope, it took a lot of time for degassing and there was a problem in terms of productivity. It is as follows. On the other hand, in the method for producing a retreaded tire according to the present invention, by injecting a heating medium into a tube disposed in a mold covering the precure tread, spaced apart from the precure tread in the tire radial direction, The unvulcanized cushion rubber is heated from the precure tread side while inflating the tube and pressing the precure tread in the inner diameter direction. Thereby, heat processing can be performed, ensuring the adhesiveness of a precure tread and a base tire simply. For this reason, compared with the method using an envelope, not only can the time required to ensure the adhesion between the precure tread and the base tire be greatly reduced, but a large vulcanizing can is not required. As a result, the method for manufacturing a retread tire according to the present invention has a reduced work time for heat treatment and is excellent in productivity.

  In the retreaded tire manufacturing method, the heat treatment may be further performed by fitting a pair of disc-shaped lid members into the tire radial direction inner portion of the bead portion from the outside. It is preferable that the unvulcanized cushion rubber is heated from the stand tire side by injecting a heating medium into the enclosed space from an injection port penetrating the lid member. According to such a manufacturing method, since the unvulcanized cushion rubber can be heated not only from the precure tread side but also from the base tire side, the vulcanization time can be further shortened, and the productivity of the retread tire is increased. Further improve.

  In the retreaded tire manufacturing method, the temperature of the heating medium injected into the tube covering the precure tread from the outside, and the temperature of the heating medium injected into the space surrounded by the lid member and the base tire Are preferably different from each other. According to this manufacturing method, optimum vulcanization conditions can be designed according to the thickness of the retreaded tire.

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

The figure which showed an example of the state of the vulcanization process of the manufacturing method of the retreaded tire which concerns on this invention

  Hereinafter, an embodiment of a method for producing a retread tire according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an example of a state of vulcanization treatment in a method for producing a retread tire according to the present invention.

  As shown in FIG. 1, the base tire 1 includes a pair of annular bead portions 11, a pair of sidewall portions 12 extending from the bead portion 11 to the outer side in the tire radial direction, and a crown portion 13 positioned between the sidewall portions 12. Have A precure tread 2 is laminated on the crown portion 13 via an unvulcanized cushion rubber 3. The unvulcanized cushion rubber 3 is heat treated to vulcanize and bond the precure tread 2 and the base tire 1.

  On the outer side in the tire radial direction of the precure tread 2, the mold 4 is spaced apart so as to cover the precure tread 2 with a certain distance. A tube 5 capable of injecting a heating medium such as heated nitrogen gas is disposed in the mold 4, and a tube is used at the time of heat treatment using an injection port 51 and a spout 52 that are provided through the mold 4. A heating medium is injected into 5. When the heating medium is injected into the tube 5, the tube 5 swells and heats the unvulcanized cushion rubber 3 through the precure tread 2 while pressing the precure tread 2 inward in the tire radial direction. As a result, the precure tread 2 is vulcanized and bonded to the base tire 1. Although the temperature of the heating medium injected into the tube 5 can be appropriately changed depending on the thickness of the precure tread 2, it is preferably 100 to 140 ° C, for example, and more preferably 110 to 130 ° C.

  As described above, the present invention includes a precure tread by injecting a heating medium into a tube disposed on the tire radial direction outer side of the precure tread and heat-treating the unvulcanized cushion rubber through the precure tread. It is also possible to vulcanize and bond the base tire. However, in order to further shorten the vulcanization treatment time, it is preferable to heat-treat the unvulcanized cushion rubber also from the base tire side. Examples of the method for heat-treating the unvulcanized cushion rubber from the base tire side include the following methods.

  A pair of disc-shaped lid members 6 are fitted from both outer sides so as to fill a gap in the tire radial direction inner side portion of the bead portion 11 of the base tire 1 shown in FIG. 1, and the pair of lid members 6 and the inner portion of the base tire 1 A sealed space 20 is provided, and the heating medium is injected into the space 20 by using the heating medium inlet 61 and the spout 62 that penetrate the lid member 6. As a result, the unvulcanized cushion rubber 3 is heated via the base tire 1, and the precure tread 2 is vulcanized and bonded to the base tire 1. The temperature of the heating medium injected into the space 20 surrounded by the pair of lid members 6 and the base tire 1 can be appropriately changed depending on the thickness of the base tire 1, but is preferably 100 to 140 ° C., for example, 110 More preferably, it is -130 degreeC.

  When the precure tread is vulcanized and bonded to the base tire via the unvulcanized cushion rubber, the thickness of the precure tread is generally larger than the thickness of the base tire. For this reason, in the present invention, when heating the unvulcanized cushion rubber not only from the precure tread side but also from the base tire side, the temperature of the heating medium injected into the tube covering the precure tread from the outside It is preferable that the temperature of the heating medium injected into the space surrounded by the lid member and the base tire is different, the temperature of the heating medium injected into the tube covering the precure tread from the outside, the lid member and The difference from the temperature of the heating medium injected into the space surrounded by the base tire is more preferably 5 to 30 ° C, and the temperature difference is particularly preferably 10 to 20 ° C.

  In the method for manufacturing a retread tire according to the present invention, since the number of steps and the time required for the vulcanization treatment are greatly reduced, the manufactured retread tire is particularly advantageous in terms of cost.

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

Comparative Example 1
A precure tread is affixed to a base tire to form a base tire with a precure tread, which is attached to a rim-like body, and an annular vulcanization envelope is placed over the base tire with a precure tread, and the envelope By degassing the inside, a base tire with a precure tread was covered with an envelope. The time required for this coating operation was defined as 100. Next, the retreaded tire (tire size 22.5 × 8.25) is obtained by performing vulcanization treatment by heating the tire with precure tread in a vulcanizing can at a vulcanization temperature of 120 ° C. for 2 hours. Manufactured.

Moreover, the durability of the retreaded tire obtained after vulcanization was evaluated by the following method.
[Tire durability test]
A test tire was assembled on a 22.5 × 8.25 wheel, the air pressure was adjusted to 900 kPa, a running test was performed on the drum under conditions of a speed of 40 km / h and a load of 3150 kg, and the running distance until failure was measured. . Evaluation is indexed with the mileage of Comparative Example 1 as 100, and if the numerical values are the same, it indicates that the tire has the same durability as the retread tire manufactured by the envelope method, and the larger the numerical value, the better the durability. Indicates.

Example 1
Using the equipment shown in FIG. 1, the uncured cushion rubber 3 is heated from the precure tread 2 side and the base tire 1 side, thereby performing vulcanization treatment to obtain a retread tire (tire size 22.5 × 8.25). ) Was manufactured. Table 1 shows the temperature of the heating medium injected into the tube 5 covering the precure tread 2 from the outside, the temperature of the heating medium injected into the space 20 surrounded by the lid member 6 and the base tire 1, and the vulcanization time. Shown in Further, the time required for injecting the heating medium into the tube 5 and the space 20 surrounded by the lid member 6 and the base tire 1 was measured using Comparative Example 1 as a reference (100). It shows in Table 1 with a durability test result.

Example 2
A retread tire was manufactured in the same manner as in Example 1 except that the temperature of the heating medium injected into the space 20 surrounded by the lid member 6 and the base tire 1 was changed to the temperature shown in Table 1. The results are shown in Table 1.

  From the results of Table 1, in the method for producing a retread tire according to Example 1-2, the productivity of the retread tire obtained according to Example 1-2 is significantly reduced without impairing the durability of the obtained retread tire. It can be seen that can be increased. In particular, in the manufacturing method of the retread tire which concerns on Example 2, since the heat | fever provided to a base tire can be reduced, it turns out that it is excellent in the durability of the manufactured base tire.

Claims (4)

Uncured on the crown portion of the base tire having a pair of annular bead portions, a pair of sidewall portions extending outward in the tire radial direction from the bead portions, and a crown portion positioned between the sidewall portions. A method for manufacturing a retread tire in which a precure tread-equipped base tire formed by attaching a precure tread to a base rubber is vulcanized and bonded to the base tire by heat treatment through a cushion rubber. ,
The precured tread is tired by inflating the tube by injecting a heating medium into a tube that is spaced apart from the precure tread in the radial direction of the tire and disposed in a mold that covers the precure tread. A method for manufacturing a retreaded tire, wherein the heat treatment is performed by heating the unvulcanized cushion rubber from the precure tread side while pressing against the radially inner side.   In the space surrounded by the lid member and the base tire, the heat treatment is further formed by fitting a pair of disc-shaped lid members into the tire radial inner portion of the bead portion from the outside. The manufacturing method of the retreaded tire of Claim 1 performed by heating the said unvulcanized cushion rubber from the said base tire side by inject | pouring a heating medium from the injection hole penetrated by the cover member.   The temperature of the heating medium injected into the tube covering the precure tread from the outside differs from the temperature of the heating medium injected into the space surrounded by the lid member and the base tire. 3. A method for producing a retread tire according to 1 or 2. A retread tire manufactured by the manufacturing method according to claim 1.

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