JP2006082389A - Method and apparatus for producing pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the waving of a tire component member stuck to a green case. <P>SOLUTION: The central part of the tire component member 7 such as a belt or a tread band is stuck to the central part in the tire width direction of the peripheral surface of the green case by a stitching roller 8. The length in the axial direction of a second molding drum 1 is shortened to W<SB>1</SB>which is preferably about 145-150% of a step in a vulcanization apparatus. When the step of the green case 6 is narrowed, by pushing out (expansion toward the periphery) of the shoulder part 6a of the green case 6, the shoulder part 6a approaches the inner surface 7b of the end part of the tire component member 7. Next, by moving the position to which the stitching roller 8 is pushed in the both end directions in the tire width direction along the peripheral surface of the tire component member 7, the inner peripheral surfaces 7b of both end parts of the tire component member 7 are stuck to the shoulder part 6a of the peripheral surface of the green case 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a manufacturing method and a manufacturing apparatus for a pneumatic tire, and more particularly to a manufacturing method and a manufacturing apparatus for a pneumatic tire capable of suppressing a compressive strain at a belt end.

The green tire molding process generally includes a two-stage process including a first molding process and a second molding process. In the first molding process, the carcass, bead core, and some tire components (inner liner, stiffener, chafer, etc.) are pasted on a cylindrical former to mold the green case, and in the second molding process, the green case is The remaining tire constituent members such as a belt and a tread band are stuck in a bulged state in a toroidal shape to obtain a green tire. Here, when sticking the remaining tire constituent members such as belts and tread bands on the green case, so-called stitching is performed by pressing from the outside of the tire constituent members with a stitching roller in order to prevent entry of air. (See Patent Document 1). The green tire molded in this way becomes a final product tire through a vulcanization process. The first molding step and the second molding step may be performed using a single molding drum, or may be performed using separate molding drums.
JP-A-8-1821

  However, when the green case is swollen in the conventional second molding step, the outer peripheral surface of the green case draws a natural curve, whereas the inner diameters at both ends in the tire width direction of tire constituent members such as belts and tread bands are required by the tire. It depends on performance and is not constant. For this reason, when the tire constituent member is affixed to the green case, the difference between the outer peripheral length of the end portion of the green case and the inner peripheral length of the end portion of the tire constituent member causes the peripheral edge of the belt due to the occurrence of compressive strain. Directional waves (undulations) appear. This wave appears prominently in spiral belts. This wave also remains in the product tire after vulcanization and becomes a main cause of separation during tire running, so that the life of the tire is shortened.

  The present invention has been made to solve such a problem, and an object thereof is to suppress the wave of the tire constituent member attached to the green case.

The invention according to claim 1 is a step of expanding the green case, and affixing a tire width direction center portion of a tire constituent member including a belt and a tread to a tire width direction center portion of an outer peripheral surface of the bulged green case. A step of expanding the outer diameter of the shoulder portion in the tire width direction of the green case, and a step of attaching the tire width direction end portion of the tire component member to the shoulder portion of the tire width direction in which the outer diameter is expanded. A method for manufacturing a pneumatic tire is provided.
According to a second aspect of the present invention, in the pneumatic tire manufacturing method according to the first aspect, in the step of expanding the outer diameter, the outer diameter is expanded by narrowing a foot width of the green case. A method for producing a pneumatic tire.
The invention according to claim 3 is the method for manufacturing a pneumatic tire according to claim 2, wherein the foot width is narrowed to about 150% of the foot width in the vulcanizing apparatus. .
The invention according to claim 4 is the pneumatic tire manufacturing method according to claim 1, further comprising a step of bending and molding the end of the tire constituent member inward in the tire radial direction. It is a manufacturing method.
According to a fifth aspect of the present invention, there is provided a molding drum, a means for bulging the green case disposed on the molding drum, and a belt and a tread at a tire width direction central portion of the outer peripheral surface of the bulged green case. Means for affixing the tire width direction center part of the tire constituent member, means for enlarging the outer diameter of the shoulder part in the tire width direction of the green case based on completion of the affixing operation by the means, and an expansion operation by the means A pneumatic tire manufacturing apparatus comprising: means for attaching a tire width direction end of the tire constituent member to a tire width direction shoulder of an outer peripheral surface of the green case based on completion.
According to a sixth aspect of the present invention, in the pneumatic tire manufacturing apparatus according to the fifth aspect, the means for enlarging the outer diameter enlarges the outer diameter by narrowing the foot width of the green case. It is the manufacturing apparatus of the pneumatic tire characterized.

(Function)
According to the present invention, the outer diameter of the shoulder portion in the tire width direction of the green case is enlarged to approach the inner diameter of the end portion in the tire width direction of the tire constituent member, thereby reducing the circumferential length difference between the outer diameter and the inner diameter. After that, the tire width direction end of the tire constituent member is attached to the tire width direction shoulder of the outer peripheral surface of the green case.

  According to the present invention, the tire width of the tire constituent member is reduced in a state where the outer peripheral length of the shoulder portion in the tire width direction of the outer peripheral surface of the green case is reduced from the inner peripheral length of the end portion in the tire width direction of the tire constituent member. Since the direction end portion is attached to the tire width direction shoulder portion of the outer peripheral surface of the green case, the wave of the tire constituent member attached to the green case is reduced.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1-6 is a figure which shows the shaping | molding method of the green tire which concerns on embodiment of this invention.
First, as shown in FIG. 1, a green case 6 including an inner liner 2, a carcass 3, a bead core 4, and a side tread 5 is held on the outer peripheral surface of the second molding drum 1. The green case 6 was molded on a first molding drum (not shown), removed from the first molding drum by a conveyance device (O-ring device) (not shown), and fitted to the second molding drum 1. Is. The second molding drum 1 can adjust the distance between the bead cores 4 at both ends of the green case 6 by expanding and contracting its axial length. Further, a bladder is attached to the drum outer peripheral surface side of the inner liner 2 so that a high-temperature and high-pressure fluid can be supplied into the bladder.

Next, as shown in FIG. 2, a bladder (not shown) is disposed inside the inner liner 2, a high-temperature / high-pressure fluid is supplied into the inner liner 2, and the axial length of the second molding drum 1 is set. By shortening, the green case 6 is expanded in a toroidal shape. Further, a tire constituent member 7 made of a belt and a tread that is separately molded is fitted to the outside of the green case 6. Here, the tire constituent member 7 includes two steel belt layers, a spiral belt layer disposed on the outer side in the tire radial direction, and a tread disposed on the outer side in the tire radial direction. The length of the second molding drum 1 in the axial direction is set so that the foot width of the green case 6 (the interval between the bead cores 4 on both sides) becomes a predetermined value W ₀ . Here, W ₀ is preferably about 170 to 175% of the foot width in the vulcanizer.

  Next, as shown in FIG. 3, a pair of stitching rollers 8 are pressed on the outer side in the tire radial direction of the central portion 7 a of the tire constituent member 7, whereby the inner peripheral surface of the central portion 7 a of the tire constituent member 7 is green-cased. 6 is attached to the center of the outer peripheral surface.

Next, as shown in FIG. 4, the foot width of the green case 6 is set to a predetermined value W ₁ (W ₁ <W ₀ ) by further shortening the axial length of the second molding drum 1. . Here, W ₁ is about 145 to 150 percent of the foot width within the vulcanizing device is preferable. Thus, when the foot width of the green case 6 is narrowed, the amount of protrusion (bulge toward the outer peripheral side) of the shoulder portion 6a of the green case 6 increases, so that the shoulder portion 6a is in the tire width direction of the tire constituent member 7. Therefore, the outer peripheral length of the shoulder portion 6a approaches the inner peripheral length of the end portion 7b, and the peripheral length difference is reduced. At this time, if the pressure applied by the bladder is increased, the degree of squeeze increases. Note that the pressure applied to the bladder may be increased from the step shown in FIG. The movement of the shoulder 6a of the green case 6 at this time is shown in FIG. As shown in this figure, the diameter of the shoulder of the carcass 3 expands in the direction of the black arrow. Further, the side tread 5 descends from the position of the solid line to the position of the dotted line as indicated by the white arrow.

  Next, as shown in FIG. 6, the positions where the pair of stitching rollers 8 are pressed are moved in the tire width direction along the outer peripheral surface of the tire constituent member 7 in the both ends of the tire constituent member 7. The inner peripheral surface 7 b is attached to the shoulder 6 a of the outer peripheral surface of the green case 6. The green tire molded in this way is conveyed to a vulcanizer and vulcanized and molded into a product tire.

  In the above embodiment, the green case 6 is molded with the first molding drum, swelled with the second molding drum, and the tire component is attached to the outer peripheral surface thereof to mold the green tire. You may make it shape | mold the green case 6 and a green tire with a drum.

(Example)
Two different types of tires were molded by the conventional method and the method of the present invention, and the results of measuring the compressive strain at the belt end are as follows. Further, FIG. 7 shows a cross-sectional view of the tread portion in the product tire of the size (1) below.

(1) Size: 1400 × 530R23
Conventional example: foot width 740 mm; (to mold foot width ratio; 172%), shaping pressure; 15 MPa, difference in circumferential length of shoulder between green case 6 and tire component 7; 81
mm, diameter difference of the shoulder; 23.6 mm, compression strain; 2%, product tire; FIG.
).

Example: foot width; 630 mm (ratio of mold foot width; 147%), shaping pressure;
17 MPa, circumference difference of shoulder portion between green case 6 and tire constituent member 7; 25
. 8mm, diameter difference of the shoulder; 7.5mm, compression strain; 0.5%, product tire;
7 (b)

(2) Size: 1270 × 455R22
Conventional: foot width; 610 mm (ratio to mold foot width; 175%), shaping pressure: 0.1
5 MPa, compression strain; 3%
Example: foot width; 540 mm (ratio to mold foot width; 150%), shaping pressure;
17 MPa, compression strain; 0.2%

  From the above results, it is confirmed that the compression strain in this example is improved to 1/4 for the tire of size: 1400 × 530R23 and 1/15 for the tire of size: 1270 × 455R22. did it. Further, the end portion of the belt layer of the product tire of the example of the size of 1400 × 530R23 shown in the region B of FIG. 7B is the same size shown in the region A of FIG. 7A. It was confirmed that there were fewer circumferential waves compared to the belt layer end of the conventional product.

In embodiment of this invention, it is a figure which shows the process of hold | maintaining a green case on the outer peripheral surface of a 2nd shaping | molding drum. In embodiment of this invention, it is a figure which shows the process of expanding a green case and fitting a tire structural member. In embodiment of this invention, it is a figure which shows the process of affixing the center part of a tire structural member on a green case. In embodiment of this invention, it is a figure which shows the process of narrowing the leg | foot width of a green case and making the shoulder part approach the edge part of a tire structural member. In embodiment of this invention, it is a figure which shows the motion of a green case shoulder part when the leg | foot width of a green case is narrowed. In embodiment of this invention, it is a figure which shows the process of affixing the both ends of a tire structural member on a green case. It is a figure which shows the arrangement | sequence state of the belt layer of the Example of this invention, and the conventional product tire.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 2nd shaping | molding drum, 6 ... Green case, 7 ... Tire structural member, 8 ... Stitching roller.

Claims (6)

A step of bulging the green case, a step of attaching a tire width direction central portion of a tire constituent member including a belt and a tread to a tire width direction central portion of an outer peripheral surface of the bulged green case, An air comprising: a step of expanding an outer diameter of a shoulder portion in the tire width direction; and a step of attaching an end portion in the tire width direction of the tire constituent member to the shoulder portion of the tire width direction in which the outer diameter is expanded. A method for manufacturing a tire. The method for manufacturing a pneumatic tire according to claim 1, wherein the step of expanding the outer diameter is to increase the outer diameter by narrowing a foot width of the green case. Method. The method for manufacturing a pneumatic tire according to claim 2, wherein the foot width is narrowed to about 150% of the foot width in the vulcanizer. The method for manufacturing a pneumatic tire according to claim 1, further comprising a step of bending and molding the end portion of the tire constituent member inward in the tire radial direction. Tire width direction of a tire constituting member including a belt and a tread at a tire width direction central portion of an outer peripheral surface of the green drum disposed on the molding drum, a green case disposed on the molding drum, and an outer peripheral surface of the green case Means for affixing the central portion; means for enlarging the outer diameter of the shoulder in the tire width direction of the green case based on completion of the affixing operation by the means; and An apparatus for manufacturing a pneumatic tire, comprising: means for attaching a tire width direction end of the tire constituent member to a tire width direction shoulder of an outer peripheral surface. 6. The pneumatic tire manufacturing apparatus according to claim 5, wherein the means for expanding the outer diameter expands the outer diameter by narrowing a leg width of the green case. apparatus.

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