JPH0414413A - Method for gas vulcanization of rubber tire - Google Patents

Abstract

PURPOSE:To prevent the lowering of the heat transfer of a vulcanizing apparatus and to reduce the temp. difference between the upper and lower parts of a tire by intermittently injecting high pressure inert gas in the vulcanizing apparatus to hold the vulcanizing pressure in the vulcanizing apparatus to a definite range and stirring the steam in the vulcanizing apparatus. CONSTITUTION:The steam in a bladder 6 supplies heat to a tire 2 during vulcanization to become condensed water 1 and this condensed water 1 is accumulated in the lower side wall part 3 of the tire 2. Since the specific gravity of high temp. steam 4 is lower than that of supplied nitrogen gas 5, said steam gathers to the upper part of the bladder 6. When the vulcanizing pressure in the bladder 6 lowers to a certain degree to reach a prescribed value or less in this state, this pressure drop is detected by a pressure switch 7 and an air operation type cut-off valve 8 is opened to send the high pressure nitrogen gas 5 into the bladder 6. When the vulcanizing pressure in the bladder 6 becomes the prescribed value, this pressure rise is detected by the pressure switch 7 and the air operation type cut-off valve 8 is closed to hold the vulcanizing pressure to a definite range. As mentioned above, by stirring the steam in the bladder 6 by intermittently injecting the high pressure nitrogen gas 5 in the bladder 6, the temp. difference between the upper and lower parts of the rubber tire 2 at the time of vulcanization can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for gas vulcanization of rubber tires and the like.

(Prior art) In the conventional gas vulcanization method for rubber tires, etc., steam, which is the main heating medium, is injected into a bladder (vulcanizing device) to heat the tire, and then high-pressure nitrogen gas is injected into the bladder. to maintain the vulcanization pressure inside the bladder within a certain range. Also at this time,
Operate the pressure regulating valve.

High pressure nitrogen gas is continuously injected into the bladder to compensate for pressure loss during vulcanization.

(Problem to be solved by the invention) In the conventional gas vulcanization method for rubber tires, etc.

Water vapor, the main heating medium, is injected into the bladder.

After the tire is heated, high-pressure nitrogen gas is injected into the bladder to maintain the vulcanization pressure within a certain range, which causes condensed water to accumulate on the lower sidewall of the tire and reduce heat transfer. As the tire pressure decreases, low-temperature nitrogen gas, which has a higher specific gravity than water vapor, collects on the lower sidewall of the tire.

There was a problem in that the temperature of the lower sidewall portion was 10 to 12°C lower than the temperature of the upper sidewall portion.

The present invention has been proposed in view of the above-mentioned problems, and its purpose is to provide a rubber tire that can prevent a decrease in the heat conductivity of a vulcanizer and can also reduce the temperature difference between the upper and lower parts of the tire. The purpose of this invention is to provide a gas vulcanization method such as the following.

(Means for Solving the Problems) In order to achieve the above object, the method for gas vulcanization of rubber tires, etc. of the present invention includes intermittently injecting high-pressure inert gas into the vulcanization device. The vulcanizing pressure inside the vulcanizer is maintained within a certain range, and the water vapor inside the vulcanizer is stirred.

(Function) As described above, in the gas vulcanization method for rubber tires, etc. of the present invention, high-pressure inert gas is intermittently injected into the vulcanization device to maintain the vulcanization pressure in the vulcanization device within a certain range. , stirring the steam in the vulcanizer.

(Example) Next, the gas vulcanization method for rubber tires, etc. of the present invention will be explained using examples (not shown in Figure 1.2). (2) in Figure 2 is a rubber tire, (2a) to (2f) are Same rubber tire (2)
temperature measurement points, (3) is the lower sidewall part of the same rubber tire (2), (1) is the lower sidewall part (3) of the same rubber tire (2),
), (4) is high-temperature steam, (5) is high-pressure nitrogen gas (high-pressure inert gas), (6) is the bladder (vulcanization equipment), and (7) is the water inside the bladder (6). A pressure switch that detects pressure, (8) is an air-operated shutoff valve installed in the high-pressure nitrogen gas supply pipe, (9) is the upper mold, (10) is the lower mold,
(11) is a four-way solenoid valve controlled by the detection signal from the pressure switch (7), and (12) is instrumentation air.

The operation of the gas vulcanization method for rubber tires, etc. of the present invention is as follows. In other words, ■ is shaping.

■ is heated with fuji, ■ is nitrogen gas pressurized, and ■ is vulcanizing.

■ is each step of degassing.

Why does the pressure inside the bladder (6) drop during vulcanization?

The water vapor in the bladder (6) supplies heat to the tire (2) and becomes condensed water (1), and as the vulcanization temperature in the bladder (6) gradually decreases, the nitrogen gas pressure increases. This is because it decreases. Condensed water (1) generated during vulcanization collects in the lower sidewall portion (3) of the tire (2). On the other hand, the high temperature water vapor (4) is transferred to the supplied nitrogen gas (5).
Because the specific gravity is smaller than that of

It gathers at the top of the bladder (6). In this state, the bladder (6
) is less than the specified value of 26 kg/dG.
When the pressure drops by approximately kg/cfflG, this pressure drop is detected by the pressure switch (7), and the detection signal obtained at that time is sent to the air-operated shut-off valve (8), which opens the air-operated shut-off valve (8). , high pressure nitrogen gas (5) into the bladder (6)
Send it inside. Furthermore, when the vulcanization pressure inside the bladder (6) reaches a specified value, this pressure increase is detected by the pressure switch (7), and the detection signal obtained at that time is sent to the air-operated shutoff valve (
8), and closes the air-operated shutoff valve (8) to maintain the vulcanization pressure in the bladder (6) within a certain range. By intermittently injecting high-pressure nitrogen gas (5) into the bladder (vulcanizer) (6) in this way and stirring the water vapor in the bladder (6).

The temperature difference between the top and bottom of the rubber tire (2) during vulcanization is 0°5°C.
Reduce it to below.

Each temperature measurement point (2a) of tire (2) 30 minutes after the start of vulcanization
) to (2f), the actual measured values of the 9th order were obtained.

In this way, in the conventional gas vulcanization method, (2a) −(
2f), there is a temperature difference of 8°C between (2b) - (2e
), there is a 16°C temperature difference between (2c) - (2cl)
There was a temperature difference of 8°C between the two.

In the present invention, the temperature difference between (2a) and (2f) is -
1” to C.

The temperature difference between (2b) - (2e) is 7°C, (2
c) The temperature difference between -(2d) became O'C, and the temperature of the tire (2) during vulcanization was averaged.

(Effects of the Invention) As described above, the gas vulcanization method for rubber tires, etc. of the present invention intermittently injects high-pressure inert gas into the vulcanization device to maintain the vulcanization pressure in the vulcanization device within a certain range. At the same time, since the water vapor inside the vulcanizer is stirred, condensed water does not accumulate in the lower part of the vulcanizer, which prevents a decrease in the heat conductivity of the vulcanizer.

This has the effect of reducing the temperature difference between the top and bottom of the tire.

[Brief explanation of drawings]

FIG. 1 is a longitudinal side view showing an example of the configuration of a vulcanizing apparatus used in carrying out the gas vulcanization method for rubber tires, etc. of the present invention, and FIG. 2 is a longitudinal side view showing various temperature measurement points of the tire.

Claims (1)

[Claims] Rubber tires, etc. characterized by intermittently injecting high-pressure inert gas into the vulcanizer to maintain the vulcanization pressure within a certain range and agitate the water vapor in the vulcanizer. Gas vulcanization method.