JP2003236950A - Method for manufacturing pneumatic tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a pneumatic tire capable of manufacturing the tire without bringing about a manufacturing fault. <P>SOLUTION: In the belt and tread assembly molding step, a belt and tread assembly 19 is obtained by laminating belt plies 12A, 12B on the outer peripheral surface of a belt molding drum 10 in which an outer peripheral sectional shape along a rotary axis is formed in a substantially circular arc shape to protrude at a radial outside to form a belt 12, spirally winding a band-like tread member 14 thereon to form a tread part 16. Since the member 14 is spirally wound, the tread part 15 can be formed without wrinkling even when the sectional shape of the outer peripheral surface of the belt is formed in a substantially circular arc shape having a small radius of curvature. In the green tire forming step, a green tire is formed by laminating the belt and tread assembly 19 on the outer peripheral surface of the previously formed band assembly. A product tire is obtained by vulcanizing to mold the green tire in a mold. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic tire manufacturing method, and more particularly to a pneumatic tire manufacturing method capable of manufacturing a pneumatic tire without causing manufacturing defects.

[0002]

2. Description of the Related Art High-speed durability of tires, improvement of steering stability,
In order to prevent manufacturing defects and improve uniformity, a number of manufacturing methods have been proposed in the past for bringing a raw tire closer to the shape of the inner surface of the mold.

Among them, as a method of bringing the shape of the tread portion before vulcanization closer to the inner surface shape of the molding, the belt forming drum has a substantially arcuate shape in which the outer peripheral cross-section along the rotation axis is convex outward in the radial direction. There is generally known a method of forming a belt by winding a wide ply around the outer peripheral surface of a so-called convex R-shaped contour drum.

[0004]

However, when the tread is attached and formed by this convex contoured R-shaped contour drum, when the circumferential length of the tread center portion and the circumferential length at the tread end portion are significantly different, that is, If the radius of curvature of the cross-section of the outer peripheral surface of the belt forming drum is small, when the tread is attached to the belt, the excess length will be wrinkled at the tread end, causing manufacturing defects. For,
There was a limit in reducing the radius of curvature of the cross section of the outer peripheral surface of the belt forming drum.

In view of the above facts, the present invention is a method for manufacturing a pneumatic tire, which can manufacture a pneumatic tire without causing manufacturing defects even when the radius of curvature of the cross section of the outer peripheral surface of the belt molding drum is small. The purpose is to provide.

[0006]

According to a first aspect of the present invention, there is provided a method for manufacturing a pneumatic tire, comprising a belt forming drum having a substantially arcuate outer peripheral cross-sectional shape along a rotation axis that is convex outward in a radial direction. And a step of applying at least one belt ply to the outer peripheral surface of the belt forming drum to form a belt, and a narrow long rubber strip made of an unvulcanized rubber composition on the outer peripheral surface of the belt. And a step of forming a tread portion by spirally winding
A belt / tread assembly forming step for forming an annular belt / tread assembly including at least the belt and the tread portion, at least a pair of bead cores, and a carcass in which the end portions are folded back around the bead core,
A raw tire in which a raw case is formed by attaching the belt / tread assembly to the outer peripheral surface of an annular band assembly having a bead filler connected to the bead core and arranged along the carcass. It is characterized by including a forming step and a vulcanization step of vulcanizing and molding the green tire with a mold.

Next, the operation of the method of manufacturing a pneumatic tire according to claim 1 will be described.

First, in the belt / tread assembly forming step, at least one belt ply is formed on the outer peripheral surface of the belt forming drum whose outer peripheral sectional shape along the rotation axis is a substantially arc shape convex outward in the radial direction. Are attached to form a belt.

The outer peripheral surface of the belt adhered to the outer peripheral surface of the belt forming drum has a substantially arcuate shape which is convex outward in the radial direction like the outer peripheral surface of the belt forming drum when viewed in a cross section along the rotation axis. Become.

Next, a narrow long rubber strip made of an unvulcanized rubber composition is spirally wound around the outer peripheral surface of the belt to form a tread portion.

The long rubber strip can be spirally wound by rotating the belt molding drum and moving the long rubber strip in the drum axial direction.

Since a strip-shaped long rubber strip having a narrow width is spirally wound, even if the outer peripheral surface of the belt has a substantially arc-shaped cross section, the belt does not wrinkle on the long rubber strip. It can be attached to the outer peripheral surface of.

As a result, a belt / tread assembly in which the belt and the tread portion are integrated with the belt forming drum can be obtained.

In the green tire forming step, the belt / tread assembly is attached to the outer peripheral surface of the preformed band assembly to form a green case.

Then, the raw tire is vulcanized by molding to obtain a product tire.

According to a second aspect of the present invention, in the method of manufacturing a pneumatic tire according to the first aspect, the thick portion of the gauge of the tread portion is longer than the thin portion of the gauge. It is characterized by a large number of windings per direction dimension.

Next, the operation of the method for manufacturing a pneumatic tire according to claim 2 will be described.

In the tread of a pneumatic tire, the gauge near the shoulder is generally set thicker than near the tread center.

In the present invention, for the portion where the gauge is thickened, the number of windings per unit axial dimension is increased as compared with the portion where the gauge is thinned.

Here, by rotating the belt forming drum at a constant angular velocity and moving the long rubber strip in the drum axial direction at a constant speed, the long rubber strip can be spirally wound with a constant thickness. However, for example, by slowing down the moving speed of the long rubber strips, the long rubber strips can overlap with each other to thicken the rubber gauge. Alternatively, after the long rubber strip is evenly wound in the drum axis direction, the long rubber strip may be further wound around the portion where the rubber gauge is to be thickened.

The invention described in claim 3 is the method for manufacturing a pneumatic tire according to claim 1 or 2, wherein
The band assembly is formed by pasting the carcass, the bead core, and the bead filler on the outer peripheral surface of the band forming drum whose outer peripheral cross-sectional shape along the rotation axis is convex in the radial direction outwardly. , Is characterized.

Next, the operation of the method for manufacturing a pneumatic tire according to claim 3 will be described.

A carcass, a bead core, a bead filler, etc. are attached to the outer peripheral surface of a band forming drum having a substantially arcuate outer peripheral cross-sectional shape along the axis of rotation to project radially outward to form a band assembly. As a result, it is not necessary to expand the outer peripheral surface into a substantially semicircular shape (there is little if any), and the carcass becomes stable.

As a result, the uniformity of the tire can be improved.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

(Manufacturing Process of Band Assembly) In FIG. 1, 21 is an annular metal band forming drum, and the outer surface shape of the band forming drum 21 is substantially the same as the inner surface shape of the product tire. It is composed of a pair of flange portions 21a extending substantially in the radial direction, and a cylindrical portion 21b connecting the outer ends of the flange portions 21a in the radial direction with each other and having an outer diameter substantially the same as the inner diameter of the product tire.

Here, the band forming drum 21 is constructed by arranging a plurality of arc-shaped segments in a circumferentially intimate contact state and connecting them to each other. As a result, when disassembling the band forming drum 21, After disconnecting the segments from each other, the segments are sequentially pulled out inward in the predetermined order in the radial direction.

A cylindrical receiving portion 21c extending outward in the axial direction is provided at the radially inner end of the collar portion 21a.
Are formed respectively.

And, such a band forming drum 21
In the case of manufacturing a pneumatic tire using, a band-shaped central inner liner 24 whose width is slightly wider than 1/3 width of a conventional inner liner is first rotated while rotating the band forming drum 21 around the central axis. The band forming drum 2
1 and is attached to the outer peripheral surface of the cylindrical portion 21b to form a cylindrical shape.

At this time, a belt-shaped outer inner liner 25 having a width of about 1/3 the width of the conventional inner liner was supplied to another drum (not shown) having a cylindrical shape and attached to the outer periphery thereof. After that, a belt-shaped cord reinforcing chafer 26 reinforced with a steel cord or an organic fiber cord is supplied to the drum, and one end in the width direction is attached to the outer periphery while being overlapped with the other end in the width direction of the outer inner liner 25. It

Next, a belt-shaped side carcass layer 27 having a width wider than the total width of the outer side inner liner 25 and the cord reinforcing chafer 26 is supplied to the band forming drum 21, and one side portion in the width direction thereof is used to form the outer side portion. The inner liner 25 and the cord reinforcing chafer 26 are covered and attached to the outer periphery of the band forming drum 21.

Next, after a bead 29 with a filler 28 is supplied and set on the outside in the radial direction of the cord reinforcing chafer 26, the cord reinforcing chafer 26 and the side carcass layer 27 on the other side in the width direction from the bead 29. Is folded back around the bead 29 toward one side in the width direction, and the side carcass layer 27 encloses the filler 28 and the bead 29.

Next, the belt-shaped side rubber 31 and the rubber chafer 32 which have been previously joined to each other are attached to the side rubber 3
1 is provided on one side in the width direction and the rubber chafer 32 is provided on the other side in the width direction, and the rubber is supplied to the drum, and the side rubber 31 and the rubber chafer 32 are attached to the periphery of the side carcass layer 27.

In this way, the filler 28 and the bead 29
The outer side inner liner 25 is attached to the innermost side while wrapping the periphery of the carcass layer 27 with the side carcass layer 27, and further the chafer wrapping the bead 29 around the side carcass layer 27, that is, the cord reinforcing chafer 26 and the rubber chafer. The fur 32 is attached, and a side assembly 33 is formed in which the side rubber 31 is attached to the periphery of the side carcass layer 27 on the tip side of the rubber chafer 32, that is, the outermost side.

Next, the pair of side assemblies 33 thus formed are expanded into a ring shape by expanding around the base end portion where the bead 29 is located, and then the receiving portion 21c.
The outer band inner liner 25 is fitted to the outer side of the band while matching the axial center, and the outer band inner liner 25 is in surface contact with the flange 21a of the band forming drum 21. Forming drum 2
Attach to both sides (outer surface) of 1.

At this time, the front end of the outer inner liner 25 and the front end of the inner portion 27a of the side carcass layer 27 are located outside both ends in the width direction of the central inner liner 24 already attached to the band forming drum 21. Are overlaid on.

In this way, the central inner liner 24, the outer inner liner 25, the cord reinforcing chafer 26, the side carcass layer 27, the filler 28, the bead 29, the side rubber 31, and the rubber chafer 32 are integrated, A band assembly 34 is formed on the outer peripheral surface of the band forming drum 21. (Belt / tread assembly forming process) In FIG. 2, 1
Reference numeral 0 denotes an annular metal belt forming drum. This belt forming drum 10 has a substantially arcuate shape whose outer peripheral cross-section along the rotation axis is convex outward in the radial direction (substantially the same shape as the carcass outer peripheral surface of the product tire). ).

In the belt / tread assembly forming step, the belt plies 12A and 12B in the form of wide belts are supplied to the rotating belt forming drum 10 and the belt ply 12
Stick A and 12B on the outer peripheral surface of the belt forming drum 10,
The belt 12 is formed.

It should be noted that one or a plurality of narrow belt-shaped belt strips each made of rubber coated with a plurality of belt cords arranged in parallel to each other are spirally wound around the outer peripheral surface of the belt forming drum 10 to form a belt (so-called spiral belt). ) 12 may be formed.

Next, as shown in FIG. 3, the belt-shaped tread member 14 is supplied to the rotating belt forming drum 10, and the tread member 14 is moved in the axial direction of the drum to form the outer periphery of the belt forming drum 10 and the belt 12. The tread member 14 is spirally attached to the surface, and the tread portion 16 is formed on the outer peripheral surfaces of the belt forming drum 10 and the belt 12.

A belt / tread assembly 19 is formed by integrating the belt 12 and the tread portion 16.

Since the belt-shaped tread member 14 is spirally wound in this way, the wrinkle-free tread portion 16 can be formed even if the outer peripheral surface of the belt has a substantially arc-shaped cross section.

The tread portion 16 has a thick gauge portion and a thin gauge portion. If the gauge is thickened, if the number of windings per unit axial dimension is increased as compared with the gauge thinned portion. good. Specifically, for example,
By slowing down the moving speed of the tread member 14 in the drum axis direction, the tread members 14 are more overlapped and the rubber gauge can be made thicker.

After the tread member 14 is evenly wound in the drum axial direction, the tread member 14 may be further wound on the portion where the rubber gauge is desired to be thickened. (Green Tire Forming Step) In the green tire forming step, the band assembly 34 and the belt / tread assembly 19 are transferred to a well-known shaping drum and removed from the belt forming drum 10 on the outer peripheral surface of the band assembly 34. The belt / tread assembly 19 and the belt / tread assembly 19
Is attached to the outer peripheral surface of the band assembly 34.

The belt / tread assembly 19 is stitched by a stitching device (not shown), and the belt / tread assembly 19 and the band assembly 34 are integrated to form a raw tire (green tire). (Vulcanization Step) After disconnecting the segments of the band forming drum 21 from each other, these segments are sequentially pulled out inward in a predetermined order, and the band forming drum 21 is taken out of the green tire. After being carried into a vulcanizer, it is vulcanized under high temperature and high pressure to obtain a pneumatic tire.

As described above, according to the pneumatic tire manufacturing method of the present embodiment, the belt-shaped tread member 14 is spirally wound around the belt 12, so that the belt forming drum 10 and the outer peripheral surface of the belt 12 are cross-sectioned. Even if the shape is a substantially arc shape having a small radius of curvature, the tread portion 16 having no wrinkles can be formed.

Further, the gauge of the tread portion 16 can be freely changed by changing the moving speed of the tread member 14, and it is not necessary to prepare a plurality of tread members for each tire size as in the conventional case.

In this embodiment, the tread portion 16 is directly attached on the belt 12, but a well-known belt reinforcing layer is appropriately provided on the belt 12, and then the tread portion 16 is provided.
May be attached.

In addition, it goes without saying that a step of providing another known reinforcing layer or the like in the tire may be added in the conventional manner.

In the present embodiment, the carcass layer 27 is separated into the left and right, but the carcass layer 27 has one bead 29.
And the other bead 29 may be straddled.

[0051]

As described above, according to the method of manufacturing a pneumatic tire of the present invention, even if the radius of curvature of the cross section of the outer peripheral surface of the belt molding drum is small, the pneumatic tire can be manufactured without causing manufacturing defects. It has an excellent effect that a filled tire can be manufactured.

[Brief description of drawings]

FIG. 1 is a sectional view of a band forming drum and a band assembly taken along a rotation axis.

FIG. 2 is a cross-sectional view of a belt forming drum and a belt along a rotation axis.

FIG. 3 is a cross-sectional view of the belt forming drum and the belt / tread assembly along the rotation axis.

FIG. 4 is a cross-sectional view of the band forming drum, the band assembly, and the belt / tread assembly along the rotation axis.

[Explanation of symbols]

10 Belt forming drum 12 belts 12A belt ply 12B belt ply 14 Tread member (long rubber strip) 16 tread section 19 Belt and tread assembly 21 band forming drum 33 band assembly

Claims (3)

[Claims] 1. A belt forming drum having a substantially arcuate shape whose outer peripheral cross-section along the rotation axis is convex outward in the radial direction, and at least one belt ply is attached to the outer peripheral surface of the belt forming drum. And a step of forming a belt,
On the outer peripheral surface of the belt, a step of forming a tread portion by spirally winding a narrow long rubber strip made of an unvulcanized rubber composition, and including, at least the belt and the tread portion. A belt / tread assembly forming step for forming an annular belt / tread assembly provided with, at least a pair of bead cores, a carcass whose end portions are folded back around the bead core, and a carcass connected to the bead cores along the carcass. A raw tire forming step of forming a raw case by pasting the belt / tread assembly on the outer peripheral surface of the band assembly formed in an annular shape having a bead filler arranged, and the raw tire in a mold And a vulcanization step of vulcanizing and forming the pneumatic tire. 2. The air according to claim 1, wherein the thick gauge portion of the tread portion has a greater number of windings per unit axial dimension of the elongated rubber strip than the thin gauge portion. Manufacturing method of filled tire. 3. The carcass, the bead core, and the bead filler are provided on an outer peripheral surface of a band forming drum having a substantially arcuate outer peripheral sectional shape along a rotation axis that is convex outward in a radial direction. The method for producing a pneumatic tire according to claim 1, wherein the pneumatic tire is formed by pasting.