JPH09117971A - Production of green case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively prevent such a state that wrinkles are generated in both of the axial end parts of a tire constituting member at a time of folding- back. SOLUTION: Both axial end parts 18b are squeezed while held to a cylindrical shape before the folding-back work thereof until an outer diameter E becomes slightly smaller than the inner diameter of a beed core 25. At this time, when the squeezing of both axial end parts 18b is performed within a range becoming 1.05-1.20 in D/E value, the generation of wrinkles can be prevented and the cord disturbance in a crown part at a time of the deformation into a toroidal shape in a rear process can be also prevented.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a manufacturing method for manufacturing a green case, which is an intermediate of a pneumatic tire.

[0002]

2. Description of the Related Art As a conventional method of manufacturing a green case, for example, a step of arranging a cylindrical tire constituent member around a tire forming drum, and a method of forming a cylindrical inner end portion of the tire constituent member in a radial direction inside a cylindrical shape While deforming,
The step of narrowing down to the inner diameter of the bead core or less and hitting the step between the axial center part and the axial end parts of the tire component with the pair of bead cores fitted to the axial end parts of the tire component. A method is known which includes a step of transferring the respective tires axially inward until they come into contact with each other, and a step of folding back a tire constituent member axially outside the bead core around the bead core.

[0003]

Here, the outer diameter of both axial ends of the narrowed tire constituent member is uniquely determined by the inner diameter of the bead core due to the constraint of fitting the bead core to the outside. However, the original outer diameter of the tire constituent member (outer diameter of the central portion in the axial direction) has been determined by the tire designer based on an empirical rule according to the type of tire to be manufactured. However, in the green case designed in this way, the amount of narrowing at both axial ends may be too large. In such a case, when the green case is actually manufactured, the shaft of the narrowed tire component is Wrinkles occur at both ends in the direction. When wrinkles occur in this way, when a product tire is obtained, the ply cord is exposed at the bead base portion, or a failure occurs at an early stage at the folding end due to the overlapping of tire constituent members at the folding portion. was there.

[0004]

Therefore, the present inventor has conducted diligent research to prevent the occurrence of such wrinkles, and narrows down the original outer diameter (outer diameter of the central portion in the axial direction) of the tire constituent member. When the ratio with the outer diameter of both axial ends is a certain value,
It was found that the generation of wrinkles as described above is prevented.

The present invention has been made on the basis of such knowledge, and a step of arranging a cylindrical tire constituent member around a tire forming drum and a method of cylindrically arranging both axial end portions of the tire constituent member radially inward. Deform while maintaining the shape,
The step of narrowing down to the inner diameter of the bead core or less and hitting the step between the axial center part and the axial end parts of the tire component with the pair of bead cores fitted to the axial end parts of the tire component. In a method of manufacturing a green case, which comprises a step of respectively moving axially inward until they come into contact with each other, and a step of folding a tire constituent member axially outside of a bead core around the bead core, narrowing down both axial end portions of the tire constituent member. In the range of 1.05 to 1.20 in which the value obtained by dividing the outer diameter D of the central portion in the axial direction by the outer diameter E of both end portions in the axial direction is 1.05 to 1.20.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an apparatus for carrying out the present invention will be described below with reference to the drawings. In FIG. 1, 11 is a cylindrical tire forming drum, and this tire forming drum 11 can be rotated about a main shaft 12 by being driven by a driving means (not shown). The tire building drum 11 has a plurality of circumferentially spaced drum segments 13 at the center in the axial direction, and these drum segments 13 can move in the radial direction. As a result,
When these drum segments 13 move inward in the radial direction, the central portion of the forming drum 11 contracts. Further, both ends in the axial direction of the tire forming drum 11 have a cylindrical shape when contracted and are deformed into a substantially donut shape when expanded.
The diameters of the bladders 14 at the time of contraction are smaller than the diameter of the axial center portion (drum segment 13) of the tire forming drum 11 at the time of expanding the diameter. A step 15 is formed between the center part of the shaft 11 in the axial direction and both end parts in the shaft direction. Then, the bladders 14 are supplied with air into the bladders 14 and expand, whereby a tire constituent member axially outside of a bead core, which will be described later, is folded back inward in the axial direction around the bead core. At this time, since each bladder 14 is pushed inward in the axial direction by a pressing means (not shown), the bladder 14 is deformed while being crushed to cover both axial end portions of the drum segment 13 to ensure the folding back.

Reference numeral 18 denotes a cylindrical tire constituent member arranged around the tire forming drum 11, for example, a carcass ply. The tire constituent member 18 has a belt-shaped ply wound around the rotating tire forming drum 11. It may be arranged around the tire forming drum 11 by joining the both ends together, or alternatively, the tire forming member 18 formed into a cylindrical shape in another forming drum is conveyed to the tire forming drum 11. It may be arranged around the tire building drum 11 by being fitted to the outside. Here, the tire constituent member 18 has an axial length in the axial center portion (drum segment) of the tire forming drum 11.
13) which is longer than the axial length, and as a result, the axial center portion 18a of the tire constituent member 18 is expanded in diameter.
When it is supported from the inside by 13, the both axial ends 18b form a predetermined gap with the bladder 14 in the contracted state.

Reference numeral 20 designates a pair of supports installed on both outer sides in the axial direction of the tire building drum 11. These supports 20 are moved in the opposite direction along the axis of the tire building drum 11 by a moving means (not shown). Moved and moved closer and further apart. The base ends of a plurality of blades 21 equidistantly spaced in the circumferential direction are rotatably connected to the respective support bodies 20, and these blades 21 extend inward in the axial direction from the support body 20 and are not shown. It is swung about the base end by the swinging means. And
After the supporting body 20 has moved to the inner limit in the axial direction by the moving means, the blades 21 swing inward in the radial direction in synchronization with the swinging means.
The axial ends 18b of 18 are pushed inward in the radial direction. Thereby, both axial end portions 18 of the tire constituent member 18
b is deformed while maintaining its cylindrical shape, and is narrowed down to a diameter not larger than the inner diameter of the bead core, which will be described later, here, slightly smaller than the inner diameter of the bead core. Here, such narrowing down of both axial end portions 18b of the tire constituent member 18 is
The outer diameter D of the axial center portion 18a is equal to the outer diameter E of the axial end portions 18b.
It must be done within the range of 1.05 to 1.20. The reason is that when the value is narrowed down to less than 1.05, when the green case is deformed into a toroidal shape in a later step, the expansion rate of the crown portion becomes too large and the radial direction is embedded in the tire constituent member 18. This is because the arrangement of the cords may be disturbed, which may cause separation in the shoulder portion. On the other hand, if the value is narrowed down to more than 1.20, the narrowed axial end portions 18
This is because the rubber between the cords embedded in b exceeds the compression limit and wrinkles occur at both axial end portions 18b. When the axial end portions 18b of the tire constituent member 18 are narrowed down in this manner, the step 15 of the tire forming drum 11 is formed between the axial center portion 18a and the axial end portions 18b of the tire constituent member 18. A step 22 extending along the side is formed.

Reference numeral 25 is a pair of ring-shaped bead cores, and a filler 26 made of rubber is attached to each of these bead cores 25. And these fillers 26
The bead core 25 provided with the bead core 25 is moved inwardly in the axial direction by a bead supply means (not shown) supporting the bead core 25, so that both end portions 18b of the tire constituent member 18 in the axial direction are provided.
While being kept fitted to the outside, the particles are transferred inward in the axial direction until they come into contact with the step 22. As a result, the bead core 25 with each filler 26 is a tire constituent member.
It is set at a predetermined position outside the 18.

Next, the operation of the embodiment of the present invention will be described. Now, a cylindrical tire component member 18 having the same outer diameter at any position (value D) is arranged around the tire forming drum 11, and both axial end portions 18b of the cylindrical tire component member 18 are expanded from the drum segment 13 in the expanded state. It is assumed to project to both outer sides in the axial direction. Next, after moving the support 20 together by the moving means to the inner limit in the axial direction, the blades 21 are rocked inward in the radial direction in synchronization with the rocking means, and the blades 21 are used to axially move the shaft of the tire constituent member 18. The both ends 18b in the direction are pushed inward in the radial direction. At this time, since a predetermined gap is formed between the axial end portions 18b of the tire constituent member 18 and the contracted bladder 14, the axial end portions 18b are allowed to deform radially inward. As a result, these axial end portions 18b are narrowed down while maintaining a cylindrical shape until the outer diameter becomes slightly smaller than the inner diameter of the bead core 25, that is, the outer diameter E. Then, such narrowing down of both axial end portions 18b of the tire constituent member 18 is performed within the range where the value of D / E is 1.05 to 1.20 as described above. As a result, wrinkles do not occur at both axial end portions 18b due to such narrowing down, and moreover, the cord is hardly disturbed in the crown portion when it is deformed into a toroidal shape in a later step.

Next, a bead core with a pair of fillers 26
25 is fitted to the outside of both axial end portions 18b of the tire constituent member 18 by the bead supply means, and is transported to the inside in the axial direction until it abuts the step 22. As a result, the bead core 25 with each filler 26 is set at a predetermined position outside the tire constituent member 18. Next, air is supplied to the inside of each bladder 14 to expand it, and the tire constituent member 18 axially outside of the bead core 25 is folded back axially inward around the bead core 25, but at this time, each bladder 14 is pressed. It is pressed axially inward by means. As a result, the bladder 14 is deformed while being crushed to cover both axial end portions of the drum segment 13, and a tire constituent member axially outside of the bead core 25.
Make sure to fold back 18 about 180 degrees. Thus the first
When the green case is molded on the tire building drum 11 of the stage, the drum segment of the tire building drum 11 is formed.
After reducing the diameter of 13, the green case is conveyed to the second stage tire building drum.

[0012]

Next, an embodiment will be described. In this embodiment, the D / E values are 1.00, 1.05, 1.10, 1.15, 1.2.
Green cases of 0 and 1.25 were manufactured, and it was inspected whether or not wrinkles were generated in the folded portions of these green cases and whether or not there was cord disorder in the crown portion when deformed into a toroidal shape. The result is D / E
In the green case with the values of 1.05, 1.10 and 1.15, there are no wrinkles and code disorder, and D / E
In the green case with a value of 1.20, wrinkles were generated only slightly, which is practically no problem, but there was no code disorder. On the other hand, in the green case in which the D / E value is 1.00, no wrinkles were generated, but there was code irregularity that could not be ignored in practical use, and the D / E value was 1.25. In the green case, the code was not disturbed, but wrinkles occurred that could not be ignored in practical use. Here, the tire inner diameter (rim diameter) of the green case was 22.5 inches. In addition, the same inspection was performed on green cases having different tire inner diameters, and similar results were obtained. From such a thing,
It is necessary to narrow down both end portions of the tire constituent member in the axial direction within a range in which the D / E value is 1.05 to 1.20.

[0013]

As described above, according to the present invention, it is possible to effectively prevent a situation in which wrinkles occur at both axial end portions of a tire constituent member when folded back.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an embodiment of the present invention.

[Explanation of symbols]

 11 ... Tire forming drum 18 ... Tire constituent member 18a ... Axial center portion 18b ... Axial end portions 22 ... Step 25 ... Bead core

Claims (1)

[Claims] 1. A step of arranging a cylindrical tire constituent member around a tire forming drum, and deforming both axial end portions of the tire constituent member radially inward while maintaining the cylindrical shape,
The step of narrowing down to the inner diameter of the bead core or less and hitting the step between the axial center part and the axial end parts of the tire component with the pair of bead cores fitted to the axial end parts of the tire component. In a method of manufacturing a green case, which comprises a step of respectively moving axially inward until they come into contact with each other, and a step of folding a tire constituent member axially outside of a bead core around the bead core, narrowing down both axial end portions of the tire constituent member. Is carried out within a range in which the value obtained by dividing the outer diameter D of the central portion in the axial direction by the outer diameter E of both end portions in the axial direction is 1.05 to 1.20.