During the curing process of conveyor belt
, the control of curing temperature and pressure is a key problem. If the temperature is too high, the rubber will warm up too fast, the temperature difference between inside and outside is too large, the inner core rubber has not been completely vulcanized, the outer layer of rubber has begun to aging; If the temperature is too low, the rubber will warm up too slowly, the vulcanization is not complete, and the joint strength cannot meet the requirements. Reasonable vulcanization temperature is generally 144℃ ~ 147℃. Vulcanization time should be determined according to the product specification provided by the conveyor belt manufacturer and the corresponding conveyor belt thickness.
For the pressure, generally speaking, should not be lower than 115MPa. Low pressure, will make the joint inside the rubber and wire rope and rubber itself bonding is not dense enough, air and some other volatile substances can not be discharged, resulting in the joint inside like bread, affecting the quality of the joint. In 1996, for example, a well the mine belt conveyor to replace tape, because at the interface when the clamp is leaking water pressure is insufficient, until at the end of the sulfide found that after cooling conveyor belt joint strip away, at that time, like a sponge rubber, steel wire rope and rubber almost no glue, can be easily pulled out from the gum, fortunately found in time to avoid the serious accident.
Conveyor belt vulcanization points for attention:
(1) Problems that should be paid attention to in the old conveyor belt vulcanization joint process
It has its particularity when the old conveyor belt is used as a port or when the old and new conveyor belts are docked. Due to the use of the old conveyor belt for many years, after many bending, there has been a separation between the steel wire rope and rubber, and the galvanized layer of the steel wire rope is also damaged due to the reaction of various elements in the rubber. Therefore, when vulcanized, the unit length adhesive force of wire rope and rubber will decrease. The way to deal with this kind of conveyor belt is to increase the lap length of the joint, the amount of increase should be determined according to the damage degree of the conveyor belt steel wire rope, generally to increase a lap length is appropriate.
(2) Requirements for conveyor belt docking center
When the conveyor belt is docked, the center line must be consistent. Otherwise, the conveyor belt will not only run off during operation, but more seriously, the stress of the steel wire rope on both sides will be uneven. The force on the short side is too large. When the force exceeds the adhesive force between a steel wire rope and the conveyor belt, this rope will be pulled out, and then other adjacent ropes will be pulled out successively, and the joint will be damaged in a very short time. If the adhesion between the wire rope and the rubber exceeds the breaking strength of the wire rope, then the high stress rope will be first pulled off, and then the other adjacent ropes will be pulled off or pulled out. It can be seen that the alignment of conveyor belt center line is a very important work when conveyor belt bonding. Therefore, when the conveyor belt is stripped of steel wire rope, ready for bonding, the vulcanization machine is fixed first, and the two sides of the conveyor belt along the direction of a stable platform of no less than 3m. Put the two conveyor belts to be glued on the platform on each side, find out the center line of the two conveyor belts (when finding the center line, find 3 points on both sides of the tape and the distance between the two points is not less than 1m), and then align them on a straight line, and fix them on the platform. Before preparing for bonding, check the center line again, and adjust it in time if there is any problem. In this way, the center line of the conveyor belt after bonding can be the same, the force of each steel wire rope is uniform, and the joint strength can be guaranteed.