The main problems of tire retreading

The main problem with tire retreading is quality. If the quality is excellent, there is no hidden danger.

       The quality problems mainly include: 1. Problems with the carcass itself; 2. Poor repair process; 3. Poor raw material quality; 4. Unstable vulcanization temperature and pressure. These can lead to failure of retreaded tires.

1. Carcass problems

       There are more than 5 carcass wounds, and the wound is larger than 5CM. The tire spout is damaged. The ply and meridian layer are damaged. These cannot be refurbished. Generally, the operator judges whether a tire can be retreaded by beating and listening. You can also choose to expand the tire detection machine and EDM detector to detect the carcass.

2. The repair process is not precise

       The repairing process mainly includes external repair, internal repair, brushing and filling. For external repairs, use a steel wheel or a cup-shaped metal grinding head to grind the worn parts, as far as possible not to damage the buffer layer or bring the layer. When grinding, follow the direction of the cord, and also grind the groove of the tire shoulder more than 10mm. The width is 20mm, in order to increase the bonding area between the tread and the carcass. The quality standard after small grinding is that the tire should be filed, all the files are filed, the grinding pattern is uniform, the cord head does not exceed 1mm, no part can be left There are bright slag, floating glue and scorch. According to the size of the hole and the number of layers of the cord that does not penetrate the hole, the internal repair is equipped with a patch for reinforcement. Use a steel wheel to polish according to the size of the patch. The thicker oil rubber can be retained but a new file must be polished Grinding surface, the actual polishing size is 10mm more than each side of the patch The model of the patch is convenient for later operation. All the plies with more than half of the carcass damage are matched according to the through hole, but the size can be slightly expanded.

3. Poor quality of raw materials

        The quality of the tread rubber directly affects the tire mileage. The role of the mid-cushion is to pull the tread from the carcass without separation. It is often said that the degumming is related to the mid-cushion. Friends who buy a tire can think about it for themselves. It costs 800 yuan to buy a 1200R-20 tire and runs 50,000 kilometers. The same type of tire can travel more than 80,000 kilometers for 1,000 yuan. Did it cost you more than 200 yuan for tires to drive 30,000 kilometers longer? You have to buy cheap tires, and manufacturers have to use cheap materials.

4. Unstable vulcanization temperature and pressure

       This problem may not be known by many tire turning factories, because the equipment manufacturers supplying them may not know the principle in between.

       Sulfuration is a chemical reaction with a temperature of 115 degrees Celsius and an error of 1 degree Celsius. Inner tube pressure 8 kg, envelope pressure 4 kg, vulcanization tank pressure 6 kg, error 0.1-0.5 kg. After the middle pad rubber reaches the specified temperature and pressure, it will produce vulcanization reaction, and use the pressure difference to effectively discharge the air of the tread rubber in the middle pad rubber. Conversely, if the temperature and pressure are not reached or exceeded, an accurate chemical reaction cannot be carried out. If there is still air in the tire, there will be a phenomenon of packing.