JP6804033B2 - Manufacturing method of vulcanized bladder and raw rubber plate - Google Patents

Description

The present invention relates to a method for manufacturing a vulcanized bladder used for manufacturing a tire and a raw material rubber plate used for the method for manufacturing the vulcanized bladder.

When vulcanizing and molding a tire, after closing the mold, a pressurized heating medium such as saturated steam is supplied into the vulcanization bladder arranged in the cavity of the raw tire to inflate the vulcanization bladder. , The raw tire is pressurized and heated by pressing the raw tire arranged in the mold against the mold.

This vulcanized bladder has a cross-sectional shape as shown in FIG. 4, for example, and the vulcanized bladder B is manufactured by press vulcanizing a raw rubber plate (slab) (see, for example, Patent Document 1). ..

5 and 6 are cross-sectional views illustrating a press vulcanization method of a vulcanization bladder, and press vulcanization is performed using the press vulcanization apparatus 1 of FIGS. 5 and 6. The press vulcanization apparatus 1 includes an upper die 2, a lower die 3, and a core (core) 4 provided between the upper die 2 and the lower die 3 and movable up and down. Hollow 11s are formed in the upper mold 2, the lower mold 3, and the core 4, respectively, and are heated to a predetermined temperature by the steam supplied to each of the hollows 11.

In the press vulcanization step, as shown in FIG. 5, first, the upper die 2 and the core 4 are raised to open the die. Next, the raw material rubber plate G cut to a predetermined length in advance is set in an annular shape with both ends aligned while being curved along the edge of the lower mold 3. Next, the upper mold 2 and the core 4 are lowered to close the mold, and the raw rubber plate G is crushed by the lowered upper mold 2 and the core 4, so that the upper mold 2 and the lower mold 3 are used. , The raw rubber is made to flow into the cavity 5 formed by the core 4. Then, vulcanization molding is performed by heating at a predetermined temperature for a predetermined time to complete the vulcanization of the vulcanization bladder.

Japanese Unexamined Patent Publication No. 2006-56172

However, in the case of the above-mentioned conventional technique, there is a problem that the manufactured vulcanization bladder frequently cracks and the yield is low.

Therefore, it is an object of the present invention to provide a manufacturing technique for a vulcanized bladder capable of suppressing the occurrence of cracks in the vulcanized bladder after manufacturing and manufacturing the vulcanized bladder with a high yield.

The invention according to claim 1
A method for manufacturing a vulcanization bladder for manufacturing a vulcanization bladder for tire vulcanization molding using a press vulcanization apparatus.
The mold of the press vulcanizer uses an upper mold, a lower mold, and a mold having a core that is arranged between the upper mold and the lower mold and has a core that can move up and down.
The mold is opened in a state in which a raw material rubber plate, which has been cut to a predetermined length in advance to form a surface to be a mating surface at both ends, is curved in an annular shape and the both ends are abutted as a mating surface. Raw material rubber plate setting process to be set on the lower mold of
With the mold closed, the set raw rubber plate is crushed by the upper mold, the lower mold and the core, and the raw rubber is inserted into the cavity formed by the upper mold, the lower mold and the core. Raw material rubber inflow process and
It has a vulcanization step of heating and vulcanizing the raw rubber that has flowed into the cavity to form a vulcanized bladder, and a taking-out step of taking out the vulcanized bladder by opening the mold.
The raw rubber plates, Ri raw rubber plates der obtained by tilting the mating surface at an angle of 25 to 65 °,
This is a method for producing a vulcanization bladder, which comprises a preheating step of heating the raw material rubber plate at a temperature of 20 to 80 ° C. for 1 hour or more in advance before the raw material rubber plate setting process .

The invention according to claim 2
The method for manufacturing a vulcanized bladder according to claim 1, wherein the raw material rubber plate is a raw material rubber plate in which the mating surfaces are inclined at an angle of 45 °.

The invention according to claim 3
The method for producing a vulcanized bladder according to claim 1 or 2, wherein the heating time in the preheating step is 8 hours or less .

The invention according to claim 4
The first to third claims are characterized in that the taking-out step is a step of separating and taking out the vulcanized bladder from the core by inflowing air between the core and the vulcanized bladder. The method for producing a vulcanized bladder according to any one item.

According to the present invention, it is possible to provide a manufacturing technique for a vulcanization bladder capable of suppressing the occurrence of cracks in the vulcanization bladder after production and manufacturing the vulcanization bladder with a high yield.

It is a perspective view which shows typically the shape of the raw material rubber plate used in one Embodiment of this invention. It is a perspective view which shows typically the shape of the raw material rubber plate used in the other embodiment of this invention. It is a perspective view which shows typically the shape of the conventional raw material rubber plate. It is sectional drawing which shows an example of the shape of the vulcanization bladder. It is sectional drawing explaining the press vulcanization method of a vulcanization bladder. It is sectional drawing explaining the press vulcanization method of a vulcanization bladder.

1. 1. Background to the Invention In the case of the above-mentioned conventional technique, the present inventor diligently investigated why the manufactured vulcanized bladder frequently cracked and the yield was low. As a result, the present inventor found that the vulcanized bladder was cracked at the first time when the raw rubber plate was pressed, because the butt joint surfaces were insufficiently crimped, and the raw rubber was insufficiently crimped. It was found that this was because the rubber flowed into the cavity with insufficient crimping. Then, in order to prevent the occurrence of cracks in the vulcanization bladder, it is necessary to sufficiently crimp the mating surfaces to each other at the first time when the raw rubber plate is pressed, and for that purpose, the crimping surface, that is, the mating surface We thought that it would be effective to increase the area.

Based on this idea, when cutting the raw rubber plate to a predetermined length, we tried to increase the area of the mating surface by cutting diagonally with respect to the longitudinal direction. As a result, a vulcanized bladder after production was attempted. It was found that the occurrence of cracks in the rubber can be suppressed.

The present invention is based on the above findings, and is characterized in that a raw rubber plate having a mating surface inclined at an angle of 25 to 65 ° is used as the raw rubber plate.

2. 2. About the mating surface of the raw material rubber plate The manufacturing method of the vulcanized bladder of the present invention is basically the same as the manufacturing method of the conventional vulcanized bladder. Hereinafter, the mating surfaces of the raw material rubber plates characteristic of the present invention will be described.

1 and 2 are perspective views schematically showing the shape of the raw rubber plate used in one embodiment and the other embodiment of the present invention, and FIG. 3 schematically shows the shape of the conventional raw rubber plate. It is a perspective view which shows. In each of FIGS. 1 to 3, (a) shows the raw material rubber plate in the state before being placed in the press vulcanizer, and (b) shows the raw material rubber plate in the state before being placed in the press vulcanizer. Note that θ is the angle of the mating surface f with respect to the bottom surface (FIG. 1) and the side surface (FIG. 2) of the raw material rubber plate G, and J is the abutting portion.

As shown in FIG. 3, in the case of the conventional raw material rubber plate G, the mating surface f is perpendicular to the longitudinal direction. On the other hand, in the present embodiment, the long raw material rubber plate is cut so that the angle θ is 25 to 65 °, more preferably 35 to 55 °, and particularly preferably 45 °, and the mating surface f is inclined. I'm letting you.

The closer the angle θ is to 90 °, the smaller the area of the mating surface f, and the butt portion J cannot be sufficiently crimped. On the other hand, the larger the difference from 90 °, the larger the area of the mating surface f, but since the thickness of the tip portion is thin, the mating surface is easily deformed during storage and preheating. On the other hand, when the angle θ is set to the above-mentioned numerical value, the area of the mating surface f can be sufficiently increased and the deformation of the mating surface can be prevented.

The direction of inclination of the mating surface f is not particularly limited, and for example, as shown in FIG. 1, the raw material rubber plate G may be inclined in the thickness direction, that is, from the upper surface to the lower surface, and the raw material may be inclined as shown in FIG. The rubber plate G may be inclined in the width direction, that is, from one side surface to the other side surface, but it is preferable to incline the rubber plate G in the thickness direction as shown in FIG. That is, when the mating surface is inclined in the thickness direction, the butt portion J faces the closing direction of the mold. Therefore, when the mold is closed, the upper mold 2 and the lower mold 3 are used. A pressing force in the vertical direction is applied to the abutting portion J from the front. As a result, the butt portion J having a large area can be crimped more reliably.

3. 3. Preheating the Raw Material Rubber Plate The raw material rubber plate G is preferably preheated to a temperature suitable for crimping before being set in the mold. Specifically, the raw rubber plate is heated at a temperature of 20 to 80 ° C. for 1 to 8 hours. As a result, the raw rubber plate G can be softened, so that the abutting portion J can be more reliably crimped.

When heated at a temperature lower than 20 ° C., the raw rubber may not be sufficiently soft, and when heated at a temperature higher than 80 ° C., vulcanization may start during preheating. Further, if the heating time is less than 1 hour, the temperature of the raw rubber may not rise sufficiently, and if the heating time exceeds 8 hours, the raw rubber may become too soft.

4. Production of Vulcanized Bladder Next, a method for producing a vulcanized bladder according to the present embodiment will be described in order of steps.

(1) Preparation before press vulcanization When performing press vulcanization, as shown in FIGS. 5 and 6, the upper mold 2 and the lower mold 3 are preliminarily closed with the mold closed. Steam is supplied to each hollow 11 of the core 4, and each is heated to a predetermined temperature suitable for vulcanization and a predetermined temperature within a predetermined temperature range. In the present embodiment, unlike the conventional case, the raw material rubber plate G is preheated in parallel with this.

(2) Raw Material Rubber Plate Setting Process The raw material rubber plate of the present invention whose mating surfaces are inclined at a predetermined angle is prepared in advance.

Next, the mold is opened. The outer peripheral edge portion of the lower mold 3 is framed by an outer peripheral wall erected substantially vertically, and an annular raw material rubber setting portion for setting the raw material rubber is provided along the inside of the outer peripheral wall. The preheated raw material rubber plate G is set in the raw material rubber set portion. Specifically, the raw material rubber plate G is placed on the raw material rubber set portion while being curved along the raw material rubber set portion, and the mating surfaces f at both ends are abutted against each other (see FIGS. 1 and 2). It is preferable that the mating surfaces of the raw rubber plates G are inclined in the thickness direction.

(3) Raw material rubber inflow step Next, the upper mold 2 and the core 4 are lowered to close the mold. In this process, the raw rubber plate G is crushed, and the raw rubber is made to flow into the cavity 5 formed by the upper mold 2, the lower mold 3, and the core 4.

At this time, in the present embodiment, since the area of the mating surface is sufficiently secured by using the raw rubber plate G in which the mating surface is inclined at a predetermined angle, the upper mold 2 and the core 4 are the raw rubber plates. Since the mating surfaces of the raw rubber plates G can be sufficiently crimped at the first time when G is pressed, the raw rubber having insufficient crimping of the mating surfaces as in the conventional case flows into the cavity 5 and is manufactured. No cracks occur in the vulcanized rubber.

(4) Vulcanization Step Also, in the method for manufacturing a vulcanization bladder according to the present embodiment, the cavity 5 is subjected to press vulcanization while keeping the mold closed for a predetermined time as in the conventional case. The raw rubber that has flowed into the inside is vulcanized by heating.

(5) Taking out step Next, the vulcanization bladder is taken out with the mold opened. Specifically, an air valve that blows air downward is provided inside the center of the lower end side of the core 4, and air is blown from the air valve in parallel with opening the mold for vulcanization. By flowing into the bladder, the vulcanized bladder is inflated like a balloon by air pressure, and the vulcanized bladder is taken out from the core 4.

In the method for manufacturing a vulcanized bladder according to the present embodiment, the vulcanized bladder is manufactured by the above steps.

As a result, the occurrence of cracks in the vulcanized bladder after production is suppressed, and the vulcanized bladder can be produced with a high yield.

Hereinafter, the present invention will be described in more detail based on Examples.

In this example, a vulcanized bladder is manufactured based on a comparative example using the conventional method and an example using the method described in the above embodiment, and cracks generated in the vulcanized bladder after the manufacture are produced. The number and incidence of vulcanizations were examined.

1. 1. Experimental method (1) Production of vulcanized bladder a. Comparative Example 50 vulcanized bladder for testing were manufactured using the raw material rubber plate G whose cut surface f shown in FIG. 3 was perpendicular to the longitudinal direction of the raw material rubber plate G and was not preheated.

b. Example Tested in the same manner as in Comparative Example except that the raw rubber plate G was previously heated at 45 ° C. for 4 hours by forming a mating surface f inclined at 45 ° in the thickness direction shown in FIG. Twenty-nine vulcanized bladder for use was manufactured.

2. 2. Evaluation of vulcanized bladder (1) Evaluation method Each of the test vulcanized bladder manufactured in Comparative Examples and Examples was used for vulcanization molding of a predetermined number (450) of tires. If cracks occur in the vulcanized bladder before the vulcanization molding of a predetermined number of tires is completed, the vulcanized bladder is counted as the number of cracks (pieces), and the crack occurrence rate (%) in each example. Asked.

(2) Evaluation results Table 1 summarizes the evaluation results.

From Table 1, the crack occurrence rate was a very high value of nearly 60% in the comparative example, whereas it was significantly reduced to 3% in the example, and according to the present invention, it was compared with the comparative example. It was found that the vulcanized bladder can be manufactured with a much higher yield, and the life of the vulcanized bladder after manufacturing can be extended.

Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. It is possible to make various modifications to the above embodiments within the same and equivalent scope as the present invention.

1 Press vulcanization equipment 2 Upper mold 3 Lower mold 4 Core 5 Cavity 11 Hollow B Vulcanization bladder G Raw material rubber plate J Butting part f Mating surface θ Angle

Claims (4)

A method for manufacturing a vulcanization bladder for manufacturing a vulcanization bladder for tire vulcanization molding using a press vulcanization apparatus.
The mold of the press vulcanizer uses an upper mold, a lower mold, and a mold having a core that is arranged between the upper mold and the lower mold and has a core that can move up and down.
The mold is opened in a state in which a raw material rubber plate, which has been cut to a predetermined length in advance to form a surface to be a mating surface at both ends, is curved in an annular shape and the both ends are abutted as a mating surface. Raw material rubber plate setting process to be set on the lower mold of
With the mold closed, the set raw rubber plate is crushed by the upper mold, the lower mold and the core, and the raw rubber is inserted into the cavity formed by the upper mold, the lower mold and the core. Raw material rubber inflow process and
It has a vulcanization step of heating and vulcanizing the raw rubber that has flowed into the cavity to form a vulcanization bladder, and a taking-out step of taking out the vulcanization bladder by opening the mold.
The raw material rubber plate is a raw material rubber plate in which the mating surfaces are inclined at an angle of 25 to 65 °.
A method for producing a vulcanization bladder, which comprises a preheating step of heating the raw material rubber plate at a temperature of 20 to 80 ° C. for 1 hour or more in advance before the raw material rubber plate setting process. The method for manufacturing a vulcanized bladder according to claim 1, wherein the raw material rubber plate is a raw material rubber plate in which the mating surfaces are inclined at an angle of 45 °. The method for producing a vulcanized bladder according to claim 1 or 2, wherein the heating time in the preheating step is 8 hours or less. The first to third claims are characterized in that the taking-out step is a step of separating and taking out the vulcanized bladder from the core by inflowing air between the core and the vulcanized bladder. The method for producing a vulcanized bladder according to any one item.

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