Difficulties in tire retreading

- Feb 11, 2019-

Difficulties in tire retreading

The main problems with tire retreading are quality issues and safety issues. If the quality is excellent, there is no hidden danger in safety.

Quality issues mainly include

1, the carcass problem

More than 5 carcass wounds, wounds greater than 5CM, damaged tire mouth, ply, meridian damage are not refurbished. It is generally up to the operator to judge whether a tire can be refurbished by tapping and listening. A tire expander and an electric spark detector can also be purchased to detect the carcass.

2, the repair process is not refined

The repairing process mainly includes external repair, internal repair, brushing and filling. Externally repair the worn parts with steel wire wheels or bowl-shaped metal grinding heads, try not to damage the buffer layer or bring layers. When grinding, follow the direction of the cords. Grind the grooves with the shoulders over 10mm. The width is 20mm to increase the bonding area between the tread and the carcass. The quality standard after the small grinding is that the tire should be honed, all honed, the grain is evenly distributed, the cord head does not exceed 1mm, and no part can be left. There are bright slag, floating glue and scorch. The internal repair is used to reinforce the patch according to the size of the hole and the number of holes that do not penetrate the hole. The wire wheel is polished according to the size of the patch. The thicker rubber can be retained but a new one must be polished. For the grinding surface, the actual grinding size is 10mm more than the side of the patch. When the patch is used, the center position of the patch must be aligned with the center of the hole or the hole, and it should not be offset. The model of the patch is marked next to it for future operation. If more than half of the carcass damage is placed in the hole, the size can be slightly enlarged. Finally, the rubber inside the tire is cleaned and transferred to the next step.

3. Poor quality of raw materials

The quality of the tread rubber directly affects the mileage of the tire. The role of the rubber in the middle is to pull the tread on the carcass without separation. It is often said that the degumming is related to the rubber in the middle. A friend who buys a retread can think for himself. It costs 800 yuan to buy a 1200R-20 tire and runs 50,000 kilometers. The same model of tire can cost more than 80,000 kilometers for 1000 yuan. If you spend more than 200 yuan on a tire and drive 30,000 kilometers, do you earn it? You have to buy cheap tires, and manufacturers have to use cheap materials.

4, vulcanization temperature and pressure instability

This problem may not be known to many retreading factories, because the equipment manufacturers that supply them may not know the principle.

Vulcanization is a chemical reaction with a temperature of 115 degrees Celsius and an error of 1 degree Celsius. The inner tube pressure is 8 kg, the envelope pressure is 4 kg, the vulcanization tank pressure is 6 kg, and the error is 0.1-0.5 kg. After the middle cushion rubber reaches the specified pressure at the specified temperature, a vulcanization reaction is generated, and the air in the middle cushion rubber is effectively discharged by using the pressure difference. On the contrary, if the temperature is not reached or exceeded, accurate chemical reaction cannot be carried out. If there is still air in the tire, there will be a phenomenon of bagging.