JP4315632B2 - Pneumatic tire manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a pneumatic tire, and more particularly to a method for manufacturing a pneumatic tire capable of manufacturing a pneumatic tire without causing a manufacturing defect.
[0002]
[Prior art]
A number of manufacturing methods have been proposed for bringing a raw tire closer to the shape of the inner surface of the mold for high-speed durability of tires, improved handling stability, countermeasures for manufacturing defects, improved uniformity, and the like.
[0003]
Among them, as a method for bringing the shape of the tread portion before vulcanization closer to the inner shape of the molding, a drum having a substantially arc shape in which the outer peripheral cross-sectional shape along the rotation axis is convex outward in the radial direction on the belt forming drum. A method of forming a belt by winding a wide ply around the outer peripheral surface of a so-called convex R contour drum is generally known.
[0004]
[Problems to be solved by the invention]
However, when forming the tread with the convex R-contour drum, the circumference of the tread center portion and the circumference of the tread end portion are greatly different, that is, the cross section of the outer peripheral surface of the belt forming drum. When the radius of curvature of the belt is small, when the tread is attached to the belt, the excess length becomes wrinkles at the end of the tread, causing manufacturing defects. There was a limit to reducing the radius of curvature of the cross section.
[0005]
In view of the above facts, the present invention provides a method for manufacturing a pneumatic tire capable of manufacturing 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 forming drum is small. Is the purpose.
[0006]
[Means for Solving the Problems]
The method for manufacturing a pneumatic tire according to claim 1 uses a belt forming drum having a substantially circular arc shape in which an outer peripheral cross-sectional shape along a rotation axis is convex outward in the radial direction, and an outer peripheral surface of the belt forming drum. A step of forming a belt by attaching at least one belt ply to the belt, and a tread by directly winding a narrow long rubber strip made of an unvulcanized rubber composition around the outer peripheral surface of the belt in a spiral shape A belt tread assembly forming step for forming an annular belt tread assembly including at least the belt and the tread portion, and an outer peripheral cross-sectional shape along the rotation axis is a radius. A car cartridge in which at least a pair of bead cores and the vicinity of the end portions are folded around the bead core on the outer peripheral surface of the band-forming drum having a substantially arc shape protruding outward in the direction. And a bead filler connected to the bead core and disposed along the carcass, forming an annular band assembly, transferring the band assembly to a shaping drum, and transferring the band assembly to the shaping drum A raw tire forming step of forming a raw case by attaching the belt tread assembly removed from the belt forming drum to a three-dimensional outer peripheral surface; and a vulcanizing step of vulcanizing and forming the raw tire with a mold; It is characterized by having.
[0007]
Next, the operation of the pneumatic tire manufacturing method according to claim 1 will be described.
[0008]
First, in the belt-tread assembly forming step, at least one belt ply is attached to the outer peripheral surface of the belt forming drum whose outer peripheral cross-sectional shape along the rotation axis is a substantially arc shape protruding outward in the radial direction. To form a belt.
[0009]
The outer peripheral surface of the belt attached to the outer peripheral surface of the belt forming drum has a substantially arc shape that is convex outward in the radial direction in the same manner as the outer peripheral surface of the belt forming drum when viewed in cross section along the rotation axis.
[0010]
Next, a narrow long rubber strip made of an unvulcanized rubber composition is directly wound spirally on the outer peripheral surface of the belt to form a tread portion.
[0011]
The long rubber strip can be directly wound spirally by rotating the belt forming drum and moving the long rubber strip in the drum axis direction.
[0012]
Since a long, narrow rubber strip is directly wound in a spiral shape, even if the cross-sectional shape of the belt outer peripheral surface is a substantially arc shape, the outer periphery of the belt can be moved without causing wrinkles on the long rubber strip. Can be pasted on the surface.
[0013]
Thereby, a belt tread assembly in which the belt and the tread portion are integrated with the belt forming drum is obtained.
[0014]
In the green tire forming step, a belt-tread assembly is attached to the outer peripheral surface of a band assembly that has been formed in advance to form a green case.
[0015]
The raw tire is vulcanized with a mold to obtain a product tire.
A band assembly is formed by attaching a carcass, a bead core, a bead filler, or the like to the outer peripheral surface of a band forming drum whose outer peripheral cross-sectional shape along the rotation axis is a substantially arc shape that protrudes radially outward. This eliminates the need to expand the outer peripheral surface into a substantially semicircular shape (if any), and stabilizes the carcass.
Thereby, the uniformity of a tire can be improved.
[0016]
According to a second aspect of the present invention, in the method for manufacturing a pneumatic tire according to the first aspect, the thick portion of the gauge of the tread portion is larger than the thin portion of the gauge per unit axial dimension of the elongated rubber strip. It is characterized by a large number of windings.
[0017]
Next, the operation of the pneumatic tire manufacturing method according to claim 2 will be described.
[0018]
In the tread of a pneumatic tire, the gauge near the shoulder is generally set thicker than that near the tread center.
[0019]
In the present invention, the portion where the gauge is thickened is dealt with by increasing the number of windings per unit axial dimension compared to the portion where the gauge is thinned.
[0020]
Here, by rotating the belt forming drum at a constant angular speed and moving the long rubber strip in the drum axis direction at a constant speed, the long rubber strip can be wound spirally with a constant thickness. By slowing down the moving speed of the long rubber strip, the long rubber strip can be overlapped to increase the thickness of the rubber gauge. In addition, after winding the long rubber strip uniformly in the drum axis direction, the long rubber strip may be further wound around the portion where the rubber gauge is to be thickened.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
[0026]
(Band assembly manufacturing process)
In FIG. 1, reference numeral 21 denotes an annular metal band forming drum, and the band forming drum 21 has a pair of flange portions 21a extending in a substantially radial direction with an outer surface shape substantially the same as an inner surface shape of a product tire. In addition, the outer ends in the radial direction of the flange portions 21a are connected to each other, and a cylindrical portion 21b whose outer diameter is substantially the same as the inner diameter of the product tire.
[0027]
Here, the band forming drum 21 is configured by arranging a plurality of arc-shaped segments in close contact with each other in the circumferential direction and connecting them together. As a result, when disassembling the band forming drum 21, the segments are arranged together. After releasing the connection, the segments are successively drawn out inward in a predetermined order.
[0028]
A cylindrical receiving portion 21c extending outward in the axial direction is formed at the radially inner end of the flange portion 21a.
[0029]
And when manufacturing a pneumatic tire using such a band shaping | molding drum 21, first, while rotating the band shaping | molding drum 21 around a central axis, a width | variety is a little more than 1/3 width of the conventional inner liner. A wide belt-shaped central inner liner 24 is supplied to the band forming drum 21 and is attached to the outer peripheral surface of the cylindrical portion 21b to form a cylindrical shape.
[0030]
At this time, a belt-like outer side inner liner 25 whose width is about 1/3 of that of a conventional inner liner is supplied to another cylindrical drum (not shown), and is attached to the outer periphery of the drum. A belt-like cord reinforcing chafer 26 reinforced with cords or organic fiber cords is supplied to the drum, and one end in the width direction is attached to the outer periphery of the outer inner liner 25 while being overlapped with the other end in the width direction.
[0031]
Next, a band-shaped side carcass layer 27 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 the outer side inner liner 25 is formed by one side in the width direction. Further, the band reinforcing drum 21 is attached to the outer periphery of the band forming drum 21 while covering the cord reinforcing chafer 26.
[0032]
Next, after a bead 29 with a filler 28 is supplied and set on the radially outer side 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 are placed on the bead. It is folded around 29 toward the one side in the width direction, and the side carcass layer 27 wraps the filler 28 and the beads 29.
[0033]
Next, the belt-like side rubber 31 and the rubber chafer 32 that are joined together in advance are supplied to the drum such that the side rubber 31 is located on one side in the width direction and the rubber chafer 32 is located on the other side in the width direction. Side rubber 31 and rubber chafer 32 are attached around side carcass layer 27.
[0034]
In this way, the periphery of the filler 28 and the bead 29 is wrapped with the side carcass layer 27, the outer inner liner 25 is attached to the innermost side, and the chafer that wraps the bead 29 around the side carcass layer 27, That is, the cord reinforcing chafer 26 and the rubber chafer 32 are affixed, and the side assembly 33 in which the side rubber 31 is affixed around the side carcass layer 27 on the tip side of the rubber chafer 32, that is, the outermost side, is formed. .
[0035]
Next, the pair of side assemblies 33 formed in this way is formed into a ring shape by expanding the base end portion where the bead 29 is located, and then the shaft core is aligned with the outside of the receiving portion 21c. Both sides of the band forming drum 21 so that the outer side inner liner 25 is on the inner side, that is, the outer side inner liner 25 is in surface contact with the flange 21a of the band forming drum 21. Affix each to the outer surface.
[0036]
At this time, the front end portion of the outer side inner liner 25 and the front end portion of the inner side portion 27a of the side portion carcass layer 27 are overlapped on the outer sides of both ends in the width direction of the central inner liner 24 already attached to the band forming drum 21. The
[0037]
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 beads 29, the side rubber 31, and the rubber chafer 32 are integrated to form a band forming drum. A band assembly 34 is formed on the outer peripheral surface of 21.
(Belt / tread assembly molding process)
In FIG. 2, reference numeral 10 denotes an annular metal belt forming drum. The belt forming drum 10 has a substantially circular arc shape (an outer peripheral surface of a carcass of a product tire) whose outer peripheral cross-sectional shape along the rotation axis is convex outward in the radial direction. And substantially the same shape).
[0038]
In the belt-tread assembly forming process, wide belt-like belt plies 12A, 12B are supplied to the rotating belt forming drum 10, and the belt plies 12A, 12B are attached to the outer peripheral surface of the belt forming drum 10, and the belt 12 is attached. Form.
[0039]
In addition, a belt-shaped belt strip (so-called spiral belt) 12 is wound around the outer peripheral surface of the belt-forming drum 10 in a spiral manner with a narrow belt-shaped belt strip coated with one or a plurality of belt cords arranged parallel to each other. It may be formed.
[0040]
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 drum axial direction so that the tread is formed on the outer peripheral surfaces of the belt forming drum 10 and the belt 12. The member 14 is affixed in a spiral shape, and the tread portion 16 is formed on the outer peripheral surfaces of the belt forming drum 10 and the belt 12.
[0041]
A belt / tread assembly 19 is obtained by integrating the belt 12 and the tread portion 16.
[0042]
Thus, since the belt-like tread member 14 is wound in a spiral shape, the tread portion 16 having no wrinkles can be formed even if the cross-sectional shape of the belt outer peripheral surface is a substantially arc shape.
[0043]
The tread portion 16 has a thick portion and a thin portion of the gauge. For the portion where the gauge is thickened, the number of windings per unit axial dimension may be increased as compared with the portion where the gauge is thinned. Specifically, for example, by slowing down the moving speed of the tread member 14 in the drum axis direction, the tread members 14 overlap each other and the rubber gauge can be thickened.
[0044]
Note that after the tread member 14 is uniformly wound in the drum axis direction, the tread member 14 may be further wound on a portion where the rubber gauge is to be thickened.
(Raw tire formation process)
In the green tire forming process, the band assembly 34 and the belt tread assembly 19 are transferred to a well-known shaping drum, and the belt tread assembly removed from the belt forming drum 10 on the outer peripheral surface of the band assembly 34. 19 is disposed, and the belt-tread assembly 19 is attached to the outer peripheral surface of the band assembly 34.
[0045]
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 into a green tire.
(Vulcanization process)
After the segments of the band forming drum 21 are released from each other, the segments are successively drawn out inward in the predetermined order, the band forming drum 21 is taken out from the raw tire, and the raw tire is carried into a tire vulcanizer. After that, a pneumatic tire is obtained by vulcanization under high temperature and high pressure.
[0046]
Thus, according to the manufacturing method of the pneumatic tire of the present embodiment, the belt-shaped tread member 14 is spirally wound on the belt 12, so that the cross-sectional shapes of the outer peripheral surface of the belt forming drum 10 and the belt 12 are curved. Even if it is a substantially circular arc shape with a small radius, the tread part 16 without a wrinkle can be formed.
[0047]
Further, by changing the moving speed of the tread member 14, the gauge of the tread portion 16 can be freely changed, and there is no need to prepare a plurality of tread members for each tire size as in the prior art.
[0049]
In addition, it is of course possible to add a step of providing other well-known reinforcing layers in the tire as usual.
[0050]
In the present embodiment, the carcass layer 27 is separated on the left and right, but the carcass layer 27 may straddle one bead 29 and the other bead 29.
[0051]
【The invention's effect】
As described above, according to the method for manufacturing a pneumatic tire of the present invention, a pneumatic tire is manufactured without causing manufacturing defects even when the radius of curvature of the cross section of the outer peripheral surface of the belt forming drum is small. It has an excellent effect of being able to.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a band forming drum and a band assembly along a rotation axis.
FIG. 2 is a cross-sectional view taken along the rotation axis of the belt forming drum and the belt.
FIG. 3 is a cross-sectional view of the belt forming drum and 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 belt 12A belt ply 12B belt ply 14 tread member (long rubber strip)
16 Tread portion 19 Belt / tread assembly 21 Band forming drum 33 Band assembly

Claims (2)

Using a belt forming drum whose outer cross-sectional shape along the rotation axis is a substantially arc shape protruding outward in the radial direction, at least one belt ply is attached to the outer peripheral surface of the belt forming drum to form a belt Forming a tread portion by directly winding a narrow long rubber strip made of an unvulcanized rubber composition spirally around the outer peripheral surface of the belt, and at least the belt A belt tread assembly molding process for forming an annular belt tread assembly including the tread portion;
An outer peripheral surface of a band forming drum whose outer peripheral cross-sectional shape along the rotation axis is a substantially arc shape protruding outward in the radial direction, at least a pair of bead cores, a carcass whose end portions are folded around the bead core, and An annular band assembly having a bead filler connected to the bead core and disposed along the carcass is formed, the band assembly is transferred to a shaping drum, and the band assembly transferred to the shaping drum is formed . A raw tire forming step of forming a raw case by attaching the belt tread assembly removed from the belt forming drum to an outer peripheral surface;
A vulcanization step of vulcanizing the green tire with a mold;
The manufacturing method of the pneumatic tire characterized by having.   2. The method for manufacturing a pneumatic tire according to claim 1, wherein the thick portion of the gauge of the tread portion has more winding times per unit axial dimension of the long rubber strip than the thin portion of the gauge. .

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