The vulcanization process of the flat conveyor belt vulcanizing machine mainly includes the following key steps and points:
Preparatory work:
Check the quantity and height of the hydraulic oil, ensure there is sufficient oil, and conduct fine filtration before the oil is injected.
Check the lubrication condition between the column shaft and the guide frame, and add oil in time to maintain good lubrication.
Connect the power supply, move the operating handle to the vertical position to close the return oil port, and start the motor to make the oil pump work.
Preheating and temperature control
Place the forming mold on the hot plate, close the rotation button, and the flat plate begins to heat up.
Set the heating temperature. Generally, the vulcanization temperature is controlled between 145 and 160° C. The specific temperature should be adjusted according to the rubber compound formula and vulcanization requirements.
Wait for the temperature of the pressure plate to reach the preset temperature and maintain it for a period of time to ensure uniform temperature.
Feeding and mold closing:
Fill the semi-finished rubber compound into the mold cavity to ensure that the rubber compound is evenly distributed and fills the cavity.
Start the pump, lift the flat plate of the flat vulcanizing machine, and lock the mold under high pressure. Some rubber product factories are equipped with high and low pressure pump stations. When starting the pump, first start the low pressure pump to quickly lift the flat plate, align it with the upper and lower molds to position the guide pins, cores and inserts, then turn off the low pressure pump, and finally start the high pressure pump to tightly lock the mold.
Vulcanization process
Within the specified vulcanization time, the product undergoes a cross-linking reaction under the action of high temperature and pressure, reaching the optimum vulcanization point.
During the vulcanization process, the pressure is generated by the hydraulic system through the hydraulic cylinder and remains stable. The vulcanization pressure is usually between 0.8Mpa and 24Mpa, and the specific pressure is adjusted according to the requirements of the product.
The vulcanization time is determined by factors such as the rubber compound formula, vulcanization temperature and product thickness. Both too long and too short times will affect the performance of the vulcanized rubber.
Exhaust and curing
During the vulcanization process, it may be necessary to perform venting operations to remove bubbles and volatile substances from the rubber compound. When venting, pressurize the mold to a certain pressure, then open the mold to release the pressure, and then close the mold again to apply pressure. Repeat this process 2 to 3 times.
After vulcanization is completed, the product remains in the mold for a period of time for curing to ensure the stability of the product’s shape and performance.
Demolding and post-processing
After the vulcanization time is completed, lower the pump and place the locked plate, then pull the mold out or push it out of the plate machine.
Use special tools or demolding mechanisms to push the vulcanized products out of the mold or pry them out by hand.
Carry out necessary post-processing on the products, such as trimming flash and inspecting quality, etc.