JP2018024109A - Manufacturing method for pneumatic tire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method for a pneumatic tire which can manufacture the tire having a shoulder part with a uniform thickness and a substantially true circular shape.SOLUTION: The manufacturing method for a pneumatic tire comprises: a first cover molding step for molding a first cover by adhering at least a carcass ply to an outer peripheral surface of a first drum; a second cover molding step for molding a second cover by adhering at least a breaker and a tread to an outer peripheral surface of a second drum; and a low cover molding step for molding a low cover by adhering the first cover to an inner peripheral surface of the second cover by arranging the first cover inside the second cover and inflating the first cover. In the second cover molding step, a breaker cushion is adhered to inside of the breaker to mold the second cover adhered with the breaker cushion.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for manufacturing a pneumatic tire used for trucks, buses, and the like.

  Pneumatic tires (hereinafter also referred to as TB tires) used for trucks and buses are usually molded with a 1st cover by attaching an inner or carcass ply to a 1st molding drum, while a breaker or A low cover (raw tire) is manufactured by attaching a tread or the like to form a 2nd cover, and then expanding the 1st cover to a volume of 1.7 to 1.9 times and attaching it to the 2nd cover (patent) References 1, 2).

  At this time, a breaker cushion which is a buffer material with an edge portion (breaker edge) of the breaker located on the inner peripheral surface of the 2nd cover is attached to a position corresponding to the shoulder portion of the carcass ply of the first cover.

Japanese Patent Laid-Open No. 08-142226 Special table WO2012 / 005029

  However, when the above method is used, when the 1st cover is inflated, the expansion of the shoulder portion becomes non-uniform, and the thickness of the shoulder portion in the manufactured tire may become non-uniform. When such non-uniformity occurs, an uneven portion is generated on the outer peripheral surface of the tire after manufacture, the tire does not become a perfect circle, and there is a possibility that uneven wear occurs in the tread portion that contacts the road surface during traveling.

  Then, this invention makes it a subject to provide the manufacturing method of the pneumatic tire which can manufacture the tire with uniform thickness of a shoulder part, and a near perfect circle.

  As a result of intensive studies to solve the above problems, the present inventor has found that the above problems can be solved by the invention described below, and has completed the present invention.

The invention described in claim 1
A pneumatic tire manufacturing method for manufacturing a pneumatic tire by molding a raw cover and vulcanizing the molded raw cover,
A 1st cover forming step of forming a 1st cover by attaching at least a carcass ply to the outer peripheral surface of the 1st drum;
A 2nd cover forming step of forming a 2nd cover by attaching at least a breaker and a tread to the outer peripheral surface of the 2nd drum;
The first cover is disposed inside the second cover, and the first cover is expanded to attach the first cover to the inner peripheral surface of the second cover to form a raw cover.
In the 2nd cover forming step, a breaker cushion is attached to the inside of the breaker to form a 2nd cover to which the breaker cushion is attached.

The invention described in claim 2
2. The method for manufacturing a pneumatic tire according to claim 1, wherein, in the first cover molding step, the carcass ply is attached after the inner is attached to the outer peripheral surface of the first drum.

The invention according to claim 3
The pneumatic tire manufacturing method according to claim 1 or 2, wherein the manufactured pneumatic tire is a truck bus tire.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the pneumatic tire which can manufacture the tire with uniform thickness of a shoulder part and a near perfect circle can be provided.

It is a perspective view explaining the 1st cover shaping | molding process of the manufacturing method of the pneumatic tire which concerns on one embodiment of this invention. It is a perspective view explaining the 2nd cover shaping | molding process of the manufacturing method of the pneumatic tire which concerns on one embodiment of this invention. It is sectional drawing which shows the raw cover shaping | molding process of the manufacturing method of the pneumatic tire which concerns on one embodiment of this invention. It is a perspective view explaining the 1st cover shaping | molding process of the manufacturing method of the conventional pneumatic tire, (A) is a figure explaining sticking of a carcass ply, (B) is a figure explaining sticking of a breaker cushion. . It is sectional drawing which shows the raw cover shaping | molding process of the manufacturing method of the conventional pneumatic tire.

1. Problems in the prior art Prior to the description of the present embodiment, problems in the prior art will be specifically described.

  4A and 4B are perspective views illustrating a first cover molding process in a conventional method for manufacturing a pneumatic tire, in which FIG. 4A is a diagram illustrating attachment of a carcass ply, and FIG. 4B is a diagram illustrating attachment of a breaker cushion. It is. FIG. 5 is a cross-sectional view showing a raw cover molding process in a conventional method for manufacturing a pneumatic tire.

  In forming the 1st cover, first, as shown in FIG. 4A, after inner (not shown) and the carcass ply 30 are laminated on the outer peripheral surface of the 1st forming drum, both side edges of the carcass ply 30 are formed. Set the bead 6 to.

  Next, as shown in FIG. 4B, two breaker cushions 10 are affixed onto the carcass ply 30 to form a 1st cover. At this time, the breaker cushion 10 is affixed at a position corresponding to the shoulder portion of the molded tire.

  On the other hand, although not shown in the drawings, in another process, a breaker and a tread are laminated on the outer peripheral surface of the 2nd molding drum to form a 2nd cover, and the molded 2nd cover is removed from the 2nd molding drum to the 1st molding drum. Transport.

  Next, the molded first cover and second cover are combined to form a raw cover.

  Specifically, as shown in FIG. 5, the 1st cover A is inserted inside the 2nd cover B in which the breaker 5 and the tread 4 are laminated. Then, by injecting air into the inside of the 1st cover A, the 1st cover A is inflated and crimped to the inner peripheral surface of the 2nd cover B, so that the 1st cover A and the 2nd cover B are combined to form a low cover. To do. Reference numeral 20 in the drawing denotes an inner attached under the carcass ply 30.

  However, in the conventional method for manufacturing a pneumatic tire, when the first cover A is inflated, the breaker cushion 10 attached on the carcass ply 30 is greatly stretched. This breaker cushion is a material made by extruding raw rubber and has the property of being easily stretched non-uniformly. Therefore, the thickness of the shoulder portion is non-uniform due to the non-uniformly stretched breaker cushion. May be. In such a case, uneven wear is caused in the tread portion that contacts the road surface during traveling in the manufactured tire.

2. SUMMARY OF THE INVENTION Accordingly, the present inventor has intensively studied a method for preventing the breaker cushion from being unevenly stretched. As a result, the inventors have come up with the idea of attaching the breaker cushion that had been attached to the 1st cover in the prior art to the 2nd cover.

  That is, unlike the 1st cover, the 2nd cover is not inflated, so that the attached breaker cushion does not extend and the thickness of the shoulder portion is prevented from becoming uneven in the formation of the low cover.

  As a result, uneven portions are not generated on the outer peripheral surface of the product tire, the tire can be manufactured in a state close to a perfect circle, and uneven wear does not occur in the tread portion.

3. Embodiments of the Present Invention Hereinafter, a method for manufacturing a pneumatic tire according to embodiments of the present invention will be specifically described with reference to the drawings.

  1-3 is a figure explaining the manufacturing method of the pneumatic tire which concerns on this Embodiment, FIG. 1 is a perspective view explaining a 1nd cover shaping | molding process, FIG. 2 is a perspective view explaining a 2nd cover shaping | molding process. FIG. 3 is a cross-sectional view showing a raw cover molding process.

(1) 1st cover molding process In the 1nd cover molding process of the manufacturing method of the pneumatic tire according to the present embodiment, first, an inner (not shown) is attached to the 1st drum, and then as shown in FIG. Then, the carcass ply 30 is stuck on the inner. Next, the beads 6 are set on both ends of the affixed carcass ply 30, and the molding of the 1st cover is completed.

(2) 2nd Cover Molding Step On the other hand, the 2nd cover is molded in parallel with the above-described 1st cover molding. In the present embodiment, unlike the conventional case, the breaker cushion is attached in this 2nd cover molding step.

  Specifically, as shown in FIG. 2, two breaker cushions 10 are attached to the outer peripheral surface of the 2nd molding drum 2. At this time, the attachment position of the breaker cushion 10 is a position corresponding to the shoulder portion after manufacture, that is, a position corresponding to the edge portion of the breaker 5 to be attached to the 2nd molding drum 2 thereafter.

  Next, after the breaker 5 is pasted on the pasted breaker cushion 10, a tread (not shown) is further pasted so as to cover the breaker 5, thereby completing the formation of the 2nd cover. Then, the molded 2nd cover is removed from the 2nd molding drum.

(3) Raw Cover Molding Step Next, the first cover and the second cover molded in the above are combined to form a raw cover. Specifically, as shown in FIG. 3, the 2nd cover B to which the breaker cushion 10 formed in the above-described process is attached is conveyed, and the 1st cover A is positioned inside the 2nd cover B.

  Then, by injecting air into the inside of the 1st cover A, the 1st cover A is expanded and pressed against the inner peripheral surface of the 2nd cover B. Thereby, the 1st cover A and the 2nd cover B are united, and the molding of the raw cover is completed.

  At this time, according to the present embodiment, since the breaker cushion 10 is affixed to the 2nd cover B, even when the 1st cover A is inflated, the breaker cushion 10 made of raw rubber is used as in the prior art. Is not stretched unevenly.

  For this reason, it is prevented that the thickness of the shoulder portion becomes nonuniform in the molding of the raw cover. As a result, uneven portions are not generated on the outer peripheral surface of the product tire, the tire can be manufactured in a sufficiently perfect circular state, and uneven wear does not occur in the tread portion.

  And when this embodiment like this is applied to the manufacture of a large size TB tire, it can exert a particularly remarkable effect.

  In the above-described embodiment, the production of the pneumatic tire in which the inner is attached under the carcass ply has been described. However, another rubber member can be attached between the inner and the carcass ply. Similarly, in the case of between a tread and a breaker, other rubber members may be appropriately added depending on the type of tire to be manufactured.

  Hereinafter, the present invention will be described based on examples.

1. Example In the example, as in the above-described embodiment, the 2nd cover to which the breaker cushion was attached was molded, and the molded 2nd cover and the 1st cover were combined to form the low cover.

2. Comparative Example In a comparative example, according to a conventional method, a 1st cover to which a breaker cushion was attached was formed, and the 1st cover was expanded and united with a 2nd cover to form a low cover.

3. Evaluation Each raw cover molded in Examples and Comparative Examples was vulcanized to produce 1200 11R22.5 size all-season pattern TB tires. Then, the roundness of the manufactured tire was measured by measuring the displacement on the tire circumference using a contact-type device, and the average value and the standard deviation σ were obtained. The results are shown in Table 1.

  From Table 1, it can be seen that in the example, the roundness of the manufactured tire is 1.05 mm, which is improved compared to the roundness of 1.22 mm in the comparative example. Also, the standard deviation σ, which is a variation index, was 0.22 in the example, which was smaller than 0.35 in the comparative example.

  From this result, in the embodiment, since the breaker cushion is affixed to the 2nd cover, the breaker cushion is not stretched by the expansion of the 1st cover, and the low cover with the uniform thickness of the breaker cushion can be formed. Was confirmed.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to said embodiment. Various modifications can be made to the above-described embodiment within the same and equivalent scope as the present invention.

2 2nd molding drum 4 tread 5 breaker 6 bead 10 breaker cushion 20 inner 30 carcass ply A 1st cover B 2nd cover

Claims (3)

A pneumatic tire manufacturing method for manufacturing a pneumatic tire by molding a raw cover and vulcanizing the molded raw cover,
A 1st cover forming step of forming a 1st cover by attaching at least a carcass ply to the outer peripheral surface of the 1st drum;
A 2nd cover forming step of forming a 2nd cover by attaching at least a breaker and a tread to the outer peripheral surface of the 2nd drum;
The first cover is disposed inside the second cover, and the first cover is expanded to attach the first cover to the inner peripheral surface of the second cover to form a raw cover.
In the 2nd cover forming step, a breaker cushion is attached to the inside of the breaker, and a 2nd cover attached with the breaker cushion is formed.   2. The method for manufacturing a pneumatic tire according to claim 1, wherein, in the first cover forming step, the carcass ply is bonded after the inner is bonded to the outer peripheral surface of the first drum.   The method for manufacturing a pneumatic tire according to claim 1, wherein the manufactured pneumatic tire is a truck bus tire.

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