Introduction To Tire Vulcanization Process

Tire vulcanization is to put the molded tire into the mold, and through the three related vulcanization elements of temperature, pressure and time, each assembly can reach the optimal vulcanization degree to obtain the physical and mechanical properties expected by the formula designer. Vulcanization is not only positive vulcanization, but also factors such as the tire body temperature after vulcanization is high and can continue to vulcanize. The vulcanization medium is currently mainly steam outside the mold and superheated water inside the tire.
1. Process flow
Robot grabs the tire--mold loading--primary shaping--secondary shaping--mold closing vulcanization--mold opening and tire removal--finished product trimming--appearance inspection--X-ray inspection.
2. Introduction to equipment used
The vulcanization equipment used for radial tires is mainly a dual-mode vulcanizer. All-steel radial tires mostly use B-type vulcanizers. B-type vulcanizers are mainly composed of tire loading mechanism, steam chamber, bladder operating mechanism, lifting mechanism, safety mechanism, tire unloading mechanism, as well as transmission system, lubrication system, pipeline system and electrical system.
All-steel radial tires do not use post-inflation devices. The vulcanization models used for all-steel radial tires are all active molds. The active molds are mainly composed of 9 fan-shaped crown modules and upper and lower side molds. The upper and lower side molds are fixed on the steam chamber, and the crown model blocks are moved by the friction plates with inclined surfaces on the inner side of the centripetal mechanism sliding up and down, so that the modules are closed or opened. The smooth surface of the model is very accurate. The small exhaust holes on the model are generally a small hole column set in the drilled hole. The inner hole of the small hole column is round or flat. The model should be cleaned regularly. The all-steel load-bearing radial tire is cleaned once every 1,000 tires produced. There are many ways to clean it. Some factories use micro-glass beads to spray under pressure and slowly move the surface of the model, but most factories use liquid cleaning agents. The surface of the liquid after cleaning must be passivated to prevent rust, or treated with polytetrafluoroethylene on the surface. There is also a new dry ice cleaning process. The mold does not need to be disassembled and can be cleaned directly on the vulcanizer, which is very convenient to operate.
3. Production process
① The tire blank should be placed in a constant temperature room for heating before being transported to the vulcanizer. If the molding area cannot maintain a constant temperature, a constant temperature room should be set up. If the molding area can maintain a constant temperature, the tire blank can be stored in the molding area. It is best to transport it to the vulcanizer 10 minutes before vulcanization;
② To prevent the tire blank from deforming, the robot should control the grabbing time. It is best to grab the tire within 5 minutes before the mold is opened. For tire blanks with large deformation, they can be grabbed 15 minutes before the mold is opened to facilitate the restoration of shape; it is not allowed to be grabbed in advance. If there are special circumstances and the lifting time is long, the tire blank should be put down, placed on the shaping tray, and transported back to the tire storage area;
③ Before vulcanization, the quality of the tire blank should be carefully checked. If there are quality defects such as loose joints, lack of glue, bubbles, and acrobatics, they should be dealt with in time. When piercing bubbles, the awl must pierce the bubbles obliquely, and the awl must not touch the wire cord;
④ Various vulcanization media, such as steam, superheated water, cooling water, power water, compressed air, pressure, temperature, clamping force, vacuum, power supply, etc. must be strictly controlled within the specified range. If there is any fluctuation, the vulcanization time must be delayed as required;
⑤ When replacing the capsule, the capsule must be preheated for no less than 15 minutes, and the vulcanized tire must be carefully checked to avoid the same defect due to capsule problems;
⑥ Check the vulcanization capsule frequently, and replace it in time if it has aging, cracks, scars, etc. Before installing the mold, the capsule must be brushed with an isolation agent, and the water on the upper and lower plates and the lower mold must be blown clean. The capsule must be in a contracted state before installing the tire;
⑦ When opening the mold, pay attention to whether the model or capsule under the outer tire is adhered. Check whether the tire unloading device is normal to avoid damaging the finished tire;
⑧ After the load-carrying radial tire is opened, it should be placed flat on the roller bed or conveyor belt behind the vulcanizer for post-vulcanization. Do not place the hot tire upright immediately after opening the mold;
⑨ The finished tire must be trimmed. The trimmed tire should maintain its appearance. If there is an inner tube, the rubber edge should be trimmed. If there is no inner tube, the rubber column must also be trimmed.
⑩ Certain defects after the appearance inspection (such as bubbles in part of the tire body, lack of rubber, etc.) should be repaired. The repaired tire should be polished and then re-inspected according to the standard.