JP2004009622A - Manufacturing method for tire - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress dispersion of a radial directional position at a tip of a bead filler and forming the bead filler which is little in variation of a wall thickness when a tire equipped with the bead filler comprising a base part having an almost triangular section and a slender rectangular tip part having a section of a thin wall is manufactured. <P>SOLUTION: A plurality of tire components are successively stuck onto a periphery of a hard core having an outer surface of a toroidal state and a green tire is molded. Besides, a strip of unvulcanized rubber is wound and the bead filler is stuck thereto. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to a method for manufacturing a tire having a bead filler having a thin rectangular cross-section and a long and narrow tip portion.
[0002]
[Prior art]
For tires, especially passenger car tires, reducing the weight is an issue in order to reduce fuel consumption, but if you try to reduce the weight of the tire components simply by reducing the dimensions, The performance of the tire will be sacrificed. Therefore, it is important to reduce the size of each member after optimizing the shape and material of each member. In the case of the sidewall portion, the bead filler is reduced in its maximum width, while the tip portion is formed into an elongated sheet-like hard material. It is known that by using rubber, the balance of rigidity required for the performance of the tire can be ensured, the torsional rigidity of the grounded tire around the vertical axis can be increased, and the entire tire can be reduced in weight.
[0003]
When molding a tire having a so-called slim high-shaped bead filler having a tip end portion of such an elongated sheet-like hard rubber, as a method of attaching the bead filler, a preset bead in which a bead core and a bead filler are previously integrated is used. The method of sticking is adopted. This preset bead 90 is formed by the method shown in FIG. FIG. 5A is a cross-sectional view showing a bead core. First, a pair of bead cores 91 are gripped so that their center axes are aligned and adjacent to each other, and both ends in the axial direction are tapered on their outer circumferences. After winding two rounds of the bead filler rubber 92 for one round, the start end and the end are crimped. Then, the center of the two bead fillers 92 in the axial direction is cut in the direction of A to form a bead filler 92A and a bead filler 92B.
[0004]
FIG. 5B is a cross-sectional view of one bead core 91 showing a step subsequent to FIG. 5A. In order to crimp the base end of the bead filler 92A and the upper surface of the bead core 91, the bead filler 92A is After expanding the diameter to a position close to the radial direction, a habit is formed in this state, and the preset bead 90 is completed. However, if the preset bead 90 is left as it is, as shown in FIG. 5 (c), it immediately returns to a position facing a direction close to the axial direction, and it is difficult to maintain and manage the shape of the preset bead 90.
[0005]
Further, when expanding the diameter of the bead filler 92A, the radius of the tip portion is largely changed, and therefore the perimeter is also largely changed. At this time, if the rigidity of the rubber material is slightly different in the partial portion. The degree of deformation varies accordingly, and the radial position of the tip varies in each tire or even in one circumferential position of a single tire, and the change in wall thickness also varies, which is a problem. In particular, when the leading end has a thin and wide sheet shape, this phenomenon is conspicuous, and has been a serious problem in terms of quality.
[0006]
On the other hand, a bead filler is wound around the outside of a carcass ply directly on the outer periphery of a cylindrical drum to form a green case, and then the green case is toroidally expanded to form a green tire. As for the manufacturing method, similarly, when expanding the diameter of the green case in a toroidal shape, it is necessary to increase the diameter of the tip of the bead filler. Therefore, it is necessary to suppress the above-described variation in the radial position and the thickness of the tip. Obviously you can't.
[0007]
[Problems to be solved by the invention]
The present invention has been made in view of such a problem, and has been made in the manufacture of a tire having a bead filler having a base having a substantially triangular cross section and a thin and elongated rectangular tip having a cross section. It is an object of the present invention to provide a manufacturing method for forming a bead filler in which the variation in the radial position of the tip of the bead filler is suppressed and the thickness of the bead filler is small.
[0008]
[Means for Solving the Problems]
To achieve the above object, the present invention has been made, and its gist configuration and operation will be described below.
[0009]
The method for producing a tire according to claim 1 is a method for producing a tire including a base having a substantially triangular cross section and a bead filler having a thin and elongated rectangular tip end.
A plurality of tire components are sequentially attached on the periphery of a hard core having a toroidal outer surface to form a green tire, and a strip of unvulcanized rubber is wound thereon to attach the bead filler.
[0010]
According to the method for manufacturing a tire according to the present invention, the bead filler is pasted on a hard core having a toroidal outer surface that is already close to the inner surface shape of the product tire, so that after the pasting, the bead filler is vulcanized. Deformation can be prevented, and variations in the radial position of the bead filler tip and changes in wall thickness can be minimized.
[0011]
In addition, since the unvulcanized strip is wound when the bead filler is attached to the core, deformation of the strip immediately after winding can be suppressed. That is, instead of winding an unvulcanized strip, a long bead filler member having a slim high shape bead filler cross section is made to make a round at a position on the outer periphery of the core, which extends in a substantially radially arcuate shape, and is attached. In the case of attaching, since the radial difference between the radially outer side and the radially inner side is large, a large tension acts on the radially outer side, and the shape of that portion becomes unstable. The method for manufacturing a tire according to the present invention also advantageously works in this regard in that variations in the radial position of the tip of the bead filler and changes in the thickness are minimized.
[0012]
According to a second aspect of the present invention, there is provided the tire manufacturing method according to the first aspect, wherein the shape of the strip forming the tip portion is a sheet shape, and the strip is wound around one layer to form the tip portion. It is.
[0013]
The thickness of the tip of the bead filler is generally effective in the range of 0.5 mm to 3 mm, which is effective in reducing the weight of passenger car tires and can secure the required rigidity. It is not preferable to form the strip by overlapping even a part of the strip because the bead filler having a rectangular cross section having a constant thickness cannot be formed due to the stretching at the overlapping portion. According to this tire manufacturing method, since the sheet-like strip is wound on one layer to form the tip of the bead filler, the tip can have a rectangular cross section with a uniform thickness, uniform rigidity and light weight. Can be contributed.
[0014]
According to a third aspect of the present invention, in the method for manufacturing a tire according to any one of the first to second aspects, a strip forming the tip portion is wound in parallel with a circumferential direction, and the bead filler is attached. .
[0015]
According to this method of manufacturing a tire, the strip is wound in parallel in the circumferential direction to form the tip, so that the radial position of the tip of the bead filler can be constant regardless of the circumferential position.
[0016]
According to a fourth aspect of the present invention, there is provided a tire manufacturing method according to the third aspect, wherein a single strip is wound to form the tip.
[0017]
According to this method of manufacturing a tire, since one end of the strip is wound to form the tip, productivity can be improved as compared with the case of forming a plurality of strips.
[0018]
According to a fifth aspect of the present invention, there is provided a tire manufacturing method according to any one of the first to fourth aspects, wherein a plurality of types of strips having different rubber materials are wound to form a bead filler.
[0019]
In this tire manufacturing method, a bead filler is formed by winding a plurality of types of strips having different rubber materials. For example, the rubber hardness can be changed at a portion of the bead filler. Therefore, it is possible to provide a more finely tuned tire that matches the use conditions.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing a passenger car tire 1 manufactured by an embodiment of the tire manufacturing method according to the present invention. The tire 1 includes two bead cores 3, a main body portion 2A of a radial carcass 2 extending in a toroidal shape between the respective bead cores 3, a folded portion 2B of the radial carcass 2 folded around the bead core 3, and a carcass portion 2 A belt 6 disposed radially outward of the main body 2A, and a tread portion 7 provided on the outer periphery of the belt 6, and a slim high shape is provided on the outer side of the main body 2A of the radial carcass 2 in the axial direction. A bead filler 10 and a side wall 9 are provided.
[0021]
The slim high-shaped bead filler 10 has a substantially triangular base 12 adjacent radially outward of the bead core, and a thin-walled elongated rectangular cross-section tip connected to the base 12 and extending radially outward. 11 is comprised.
[0022]
A manufacturing method for molding a tire having such a slim high-shaped bead filler 10 will be described below. FIG. 2 is a cross-sectional view of the hard core 20 showing a method of attaching the bead filler 10 of the tire shown in FIG. First, an inner liner 21 is attached by winding a strip around the outer periphery of a hard core 20 which can be disassembled into a plurality of segments annularly adjacent to each other and has a toroidal outer surface corresponding to the inner peripheral surface of the tire 1. Next, after a carcass ply 22 made of a cord extending in the radial direction is attached by a method such as knitting, bead cores 24 are attached to both ends in the axial direction from outside in the axial direction. Next, the unvulcanized strip is wound to form a bead filler 25 having a slim high shape outside the carcass ply in the axial direction. Then, the both sides 23 of the carcass ply 21 are folded outside the bead filler 25 to form a folded portion of the carcass ply.
[0023]
An example of a method for forming the bead filler 25 with a strip will be described below. FIG. 3 is a cross-sectional view of a bead filler 25 showing a first strip winding method, in which a base 25A is formed by spirally winding a strip 26 having a quadrangular cross section whose opposing long sides are slightly inclined with respect to each other. It is formed by winding a plurality of strips continuously. On the other hand, the distal end portion 25B is formed by winding a narrow sheet-like strip 27 having the same width as the radial height of the distal end portion 25B one round and parallel to the circumferential direction, separately from the strip 26 forming the base portion 25A. The starting end and the end of 27 are butt-joined and formed.
[0024]
In this embodiment, since a single strip 26 is wound in the circumferential direction to form the distal end portion 25B, the height of the distal end portion 25B in the radial direction can be made uniform in the circumferential direction.
[0025]
FIG. 4 is a cross-sectional view of the bead filler 25, showing a method of winding the second strip. The base 25A of the bead filler 25 is formed by continuously winding the strip 28 in a plurality of spiral turns. The portion 25B is formed by winding a sheet-like strip 29 having a rectangular cross section into three layers.
[0026]
In forming the distal end portion 25B, the strip 26 may be wound one turn at a time in parallel with the circumferential direction, or may be continuously wound spirally. When the strip 26 is wound one turn at a time in parallel with the circumferential direction, the radially outer end of the tip portion 25B is made uniform at a uniform height in the circumferential direction, thereby further suppressing rigidity variations in the circumferential direction. be able to. Further, when the strip 26 is continuously wound in a spiral shape, there is no need to perform processing such as positioning the start end and the end or cutting the strip for each round, and the cycle time of molding is reduced. Can be shortened.
[0027]
Further, in FIG. 4, the strip 28 forming the base portion 25A and the strip 29 forming the tip portion 25B can be continuous. In this case, the cycle time of molding can be further reduced. it can.
[0028]
Further, the strip 28 forming the base portion 25A or the strip 29 forming the distal end portion 25B can be composed of a plurality of strips made of different materials, and the rigidity is changed for each part of the cross section of the bead filler 25 to improve the tire performance. If it is desired to respond to the request for the information in a very detailed manner, it can be advantageously used for this purpose. In order to make the rigidity distribution of each section of the cross section finer, the cross section of the strip may be made smaller.
[0029]
【The invention's effect】
As is apparent from the above description, according to the present invention, a plurality of tire components are sequentially attached on the circumference of a hard core having a toroidal outer surface to form a green tire, and the unvulcanized rubber is molded. A method of manufacturing a tire, in which a strip is wound and a bead filler is stuck, so that a variation in the radial position of the tip of a so-called slim high-shaped bead filler is suppressed and a bead filler with a small change in wall thickness is formed. Can be.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a tire manufactured using an embodiment of a tire manufacturing method according to the present invention.
FIG. 2 is a cross-sectional view of a hard core, showing an embodiment of the tire manufacturing method according to the present invention.
FIG. 3 is a sectional view of a bead filler showing a method of winding a first strip.
FIG. 4 is a sectional view of a bead filler showing a method of winding a second strip.
FIG. 5 is a cross-sectional view showing a conventional method for forming a preset bead.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 Passenger car tire 2 Radial carcass 2A Radial carcass main body 2B Radial carcass turn-back portion 3 Bead core 6 Belt 7 Tread portion 9 Sidewall portion 10 Bead filler 11 Bead filler base 12 Bead filler tip 20 Hardcore 21 Inner liner 22 Carcass ply 23 Both sides 24 of carcass ply Bead core 25 Bead filler 25A Bead filler base 25B Bead filler tip 26, 27, 28, 29 Strip

Claims (5)

A method for manufacturing a tire comprising a base having a substantially triangular cross section and a bead filler having a thin cross section and an elongated rectangular tip,
A method of manufacturing a tire in which a plurality of tire components are sequentially attached on a circumference of a hard core having a toroidal outer surface to form a green tire, and a strip of unvulcanized rubber is wound and the bead filler is attached. The tire manufacturing method according to claim 1, wherein a shape of the strip forming the tip portion is a sheet shape, and the strip is wound around a single layer to form the tip portion. The method for manufacturing a tire according to claim 1, wherein the bead filler is attached by winding a strip forming the front end portion in parallel with a circumferential direction. The method for manufacturing a tire according to claim 3, wherein the tip portion is formed by winding a single strip. The method for producing a tire according to any one of claims 1 to 4, wherein a bead filler is formed by winding a plurality of types of strips having different rubber materials.

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