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Treatment of common equipment related vulcanization process defects of all steel radial truck tire

in recent years, with the development of China's transportation industry, the demand for truck tire has increased. In the maintenance market, users have also realized the advantages of using all steel radial truck tire, especially in long-distance and large volume transportation. Therefore, all steel radial truck tire has been more and more widely used. Due to the harsh service conditions and strict requirements on the quality of all steel radial truck tire, many defects appear in the process of use, many of which are closely related to the service state and assembly of the equipment. This paper analyzes several common equipment related vulcanization process defects of all steel radial truck tire, and puts forward solutions

1 bead deformation

after the embryo enters the vulcanization process, the waste products caused by bead deformation are mainly due to poor vacuum pumping of the vulcanizer. There are many reasons for the poor vacuum pumping of the curing machine. The following is the analysis of the vacuum pumping of the curing machine

1.1 it is reflected in the poor vacuum pumping of a single curing machine

at this time, it should be considered whether the corresponding pneumatic valve on the inlet and outlet capsule pipeline of the machine is tightly closed. Such as: finalized steam inlet balance valve, primary water inlet shut-off valve, secondary water inlet shut-off valve, etc. In general, the valve core of the pneumatic shut-off valve is easy to fall off or get stuck by foreign matters during repeated lifting and lowering movements, resulting in the valve not being closed tightly, so that there is continuous medium entering the capsule, and the vacuum pumping is naturally not good. The above listed conditions cause unnecessary pressure in the capsule, so it is often called inverted internal pressure

solution: check the pipelines entering the capsule medium of the machine one by one, that is, the finalized steam inlet, primary water inlet, secondary water inlet and other pipelines. Find the pneumatic valve that cannot be closed tightly and repair or replace it according to the situation. However, when repairing or replacing such valves, pay attention to emptying the residual medium in the corresponding pipeline, otherwise the residual superheated water or steam is easy to hurt people

1.2 is reflected in the poor vacuum pumping of many vulcanizers

1.2.1 the valve between the vacuum power water pipe and the vacuum pump pipe is not closed

the radial tire dual-mode vulcanizer used by our company has two sets of devices for vacuum pumping. One is to use dynamic polyoxymethylene, an engineering plastic with good performance. Water is forced to produce negative pressure and vacuum through the ejector. Second, vacuum with vacuum pump. When vacuumizing with a vacuum pump, the ball valve between the two must be closed, otherwise the vacuum pump will pump out a large amount of power water rather than the medium in the capsule. And because the vacuum pump pumps a lot of power water, the vacuum degree produced by it will inevitably be reduced, which will affect the vacuum pumping quality of many vulcanizers

1.2.2 the solenoid valve controlling the vacuum pumping is not reset

the solenoid valve controlling the vacuum pumping of the vulcanizer is not reset, so that when the vulcanizer starts to take the automatic step, the vacuum pumping shut-off valve will be opened, and the medium in the capsule will also be continuously pumped away by the vacuum pump. The vacuum degree produced by the vacuum pump will be reduced, which will affect the vacuum pumping quality of multiple vulcanizers

1.2.3 the mechanical valve controlling the gas source switching is not pressed in place

the thermal pipeline system of the radial tire dual-mode curing machine used by our company is mainly composed of two parts: the first part is controlled by the program controller (vulcanization solenoid valve group) after the mold is closed, that is, various media (steam, superheated water, etc.) entering and leaving the capsule and steam chamber during the vulcanization process are controlled according to the set program; The second part is to complete a series of actions such as vacuum pumping, automatic lubrication, shaping, tire unloading, etc. through the cooperation of the master controller and the travel switch after mold opening. These actions are performed by the above two controllers and send gas or electrical signals to the actuator (valve, cylinder, water cylinder, etc.) through other electrical components in the electrical cabinet to complete the above action requirements

the above two parts of action are switched by a two position five way mechanical valve, which is installed on the wall panel of the vulcanizer. When closing the mold, the mechanical valve is pressed, and the control air source is connected to the program controller to make the first part of the pneumatic element act, while cutting off the control air source of the second part of the controller. When opening the mold, it is the opposite

if the mold of a vulcanizer is closed in place (referring to the rotation code value is in place, and the vulcanization program starts to go), but the mechanical valve is not closed in place under the new normal state due to its installation position and other reasons, that is, the switch between the two parts of the control air source is not realized, so that both parts of the controller are controlled by the air source, so that the pneumatic shut-off valve on the vacuum pipe is opened at the beginning of the vulcanization program. During the vulcanization process, the medium passing through the capsule (setting steam, primary and secondary water) is continuously pumped away by the vacuum pump. The vacuum degree produced by the vacuum pump will be reduced, which will affect the vacuum pumping quality of multiple vulcanizers

solution: to solve the vacuum pumping problem in the above three cases, check the vulcanizer one by one. In the first case, close the ball valve between the vacuum pumping power water and the vacuum pump pipeline. In the second case, replace the solenoid valve. In the third case, the position of the mechanical valve or the limit position of the valve should be changed to effectively switch the air source

2 flash first try

2.1 lip flash

the main reasons for lip flash after vulcanization are:

1 The gap between the embryo and the steel diamond ring is too large due to the wrong use of the steel diamond ring

2. The poor alignment of the manipulator results in irregular coordination between the embryo mouth and the steel diamond ring

solution: check the steel diamond ring and replace the wrong steel diamond ring. If it is judged that the manipulator is not well aligned, adjust the alignment of the manipulator

2.2 flash at other places

there are tire shoulders between the flexible modules and the joints between the upper and lower side plates and the flexible modules, or flash and release at both sides. The specific reason should be excessive tire embryo rubber or mold assembly problems. Solution: check the size of tire crown and sidewall. Check the mold assembly

3 tire shoulder and sidewall lack of rubber

there is insufficient circumferential rubber on one or both sides of the tire shoulder. The main causes are as follows:

1 The vulcanizer leaks water, or the external pressure steam is poured back, so that the water or steam is sprayed on the mold and capsule. The vaporized gas of these water or steam during vulcanization cannot be eliminated, which affects the flow of rubber

2. The mold exhaust hole is blocked, or the distribution of the exhaust line of the mold exhaust hole is unreasonable, and the air between the rubber and the mold is not easy to be discharged during vulcanization, which affects the rubber flow

solution: check the equipment to prevent water or steam from splashing on the mold and embryo, strengthen the inspection of the mold exhaust hole to keep it unobstructed, and if necessary, add exhaust holes or exhaust lines at the places where it is easy to lack glue. (end)

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