JPH0223329B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) This invention relates to a tire vulcanization method including a cooling step.

(Prior art) Conventionally, as this type of tire vulcanization method, the first
As shown in the figure, a tire 2 loaded into a mold 1
It is generally well known that the cooling water 4 is cooled by cooling water 4 injected into the bladder 3.

However, in the conventional tire curing method described above, when the cooling water 4 is injected into the bladder 3, the internal pressure medium in the bladder 3, especially in the case of a low heat capacity gas, cannot be completely evacuated. The internal pressure medium 5 inevitably remains, and therefore the second
As shown in the figure (curves A, B, and C in Figure 2 correspond to parts A, B, and C in Figure 1, respectively), part A where the residual internal pressure medium exists is not cooled sufficiently, and the tire The problem was that the nylon cord was not cooled uniformly, leading to a decrease in the strength of the nylon cord and resulting in a decrease in quality.

Therefore, blow steam into the bladder,
A method of forcibly discharging the internal pressure medium in the bladder may be considered, but in this case, there is a problem that the accumulation of internal pressure medium cannot be completely removed by blowing for a short time. In addition, when the supply of cooling water is started in the next process after discharging the internal pressure medium by steam blowing, the blowing steam inside the bladder is rapidly cooled, causing the internal pressure of the bladder to drop instantaneously. However, there is a drawback that the strength of the tire cord tends to decrease.

(Object of the invention) Therefore, the object of the invention is to
The gas inside the bladder can be completely removed in a short period of time to cool the tire uniformly and sufficiently, and the pressure inside the bladder will not change suddenly when cooling water is injected, improving the quality of the tire. be.

(Structure of the invention) In order to achieve the above object, the structure of this invention is as follows.
Immediately before the cooling process in which the tire loaded in the mold is cooled with cooling water through the bladder, the pressure between the inner surface of the tire and the bladder is maintained while maintaining the internal pressure medium in the bladder so as not to fall below a predetermined value. Pressurizing high-pressure gas for expulsion into the bladder to deflate the bladder to discharge the internal pressure medium in the bladder, and then ensuring that the high-pressure gas for expulsion between the inner surface of the tire and the bladder does not fall below a predetermined value. The tire is characterized in that cooling water is press-injected into the tire while the tire is held in the same position.

(Example) Hereinafter, the present invention will be explained in detail with reference to illustrated examples.

As shown in FIG. 3, the apparatus used in this embodiment consists of an upper mold 7 and a lower mold 8, a mold 1 into which a tire 2 is loaded, and a mold 1 that presses the tire 2 against the inner surface of the mold 1. It includes a molding bladder 3, and upper and lower bladder rings 11 and 12 that support the bladder, and further includes the upper and lower bladder rings 11,
12 is provided with passages 15, 15 for introducing steam as an example of expelling gas between the bladder 3 and the inner surface of the tire 2.

In this tire vulcanization method, the steps shown in FIG. 4 are performed. First, a heating process consisting of a well-known steam process and a low heat capacity gas process is performed.

Then, one minute before the end of the low heat capacity gas step and the start of cooling water supply (by tire control), valve V ₄ shown in Fig. 3 is opened, and 17 kg/cm ² of steam is passed through the passages 15 and 15 from above and below. Pressure fitting between the inner surface of the tire 2 and the bladder 3 begins. After 5 seconds have elapsed from the start of this press-fitting, the valve V ₆ is opened, and the internal pressure medium in the bladder 3 is gradually removed while adjusting the pressure in the bladder 3 using the orifice 17 so that it does not fall below 10 kg/cm ² . The reason why the internal pressure inside the bladder 3 is maintained so that it does not go below 10 kg/cm ² is that if it goes below 10 kg/cm ² , the double molding or the cord inside the tire will be displaced, and the tire 2 will be damaged. This is because it adversely affects quality. One minute after the internal pressure medium 5 in the bladder 3 is started to be removed, the internal pressure medium 5 in the bladder 3 is completely exhausted and steam 21 is generated between the tire 2 and the bladder 3, as shown in FIG. Fill up.

Then enter the cooling process, open valve V ₃ ,
As shown in FIG. 6, the supply of cooling water 4 is started. After 2 seconds from this start, valve V ₅
In order to prevent the steam 21 between the inner surface of the tire 2 and the bladder 3 from losing its pressing force against the tire 2, the steam pressure is adjusted using the orifice 22 so that the steam pressure does not fall below 10 kg/ ^cm2 . Remove it gradually. In this way, we move on to the cooling process and open valve _V8 to circulate the cooling water.
After that, open the V ₆ and move on to the normal exhaust process,
Open the mold 1 and take out the tire 2. The vulcanized tire 2 is thus cured as shown in FIG.
Curves A, B, and C in the figure correspond to portions A, B, and C in Figures 3, 5, and 6, respectively. ), it can be seen that by discharging the residual internal pressure medium by injecting the expulsion steam 21, the temperature, that is, the amount of vulcanization in each part of the tire becomes approximately equal. Therefore, tire 2
This results in improved quality and improved productivity by shortening the cooling period.

In the above embodiment, since steam is used as the expelling gas, even if steam 21 remains between the inner surface of the tire 2 and the bladder 3, this steam 21 is cooled by the cooling water 4 and drops into water droplets. Therefore, no air layer is formed between the inner surface of the tire 2 and the bladder 3, and therefore, the tire 2 can be cooled uniformly and quickly without causing cooling failure.

In the above embodiments, steam is used as the expelling gas, but other gases such as air or liquids such as water may also be used. Note that the low heat capacity gas is, for example, nitrogen gas.

(Effects of the Invention) Since the tire vulcanization method of the present invention is configured as described above, the tire can be cooled uniformly and sufficiently, the quality of the tire can be improved, and productivity can be improved.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the conventional tire vulcanization method, Figure 2
The figure is a characteristic diagram of the above method, FIG. 3 is a sectional view of a device used in an embodiment of the present invention, FIG. 4 is a process explanatory diagram of the above embodiment, and FIGS. FIG. 7 is a characteristic diagram of the above embodiment. 1... Mold, 2... Tire, 3... Bladder,
4...Cooling water, 5...Low heat capacity gas, 17,22
...Orifice, 21... Gas for expulsion.

Claims (1)

[Claims] 1. In a tire vulcanization method including a cooling step of cooling a tire loaded in a mold with cooling water via a bladder, immediately before the cooling step, the pressure of the internal pressure medium in the bladder is reduced. While maintaining the pressure so as not to fall below a predetermined value, expulsion high-pressure gas is injected between the inner surface of the tire and the bladder to contract the bladder and discharge the internal pressure medium in the bladder, and then A tire vulcanization method characterized in that cooling water is pressurized into the bladder while maintaining a high pressure expelling gas between the inner surface of the tire and the bladder so as not to fall below a predetermined value.