Causes of belt conveyor slipping
1.Water ingress on belt surface
Due to the change of natural environment, on-site ground flushing, equipment maintenance and other reasons, water, oil, ice, frost and other attachments with certain lubrication effect are adhered to the non working surface of the belt. As the belt moves to the main drum, the contact conditions between the two will change, the water flow plays a lubrication role, and the friction coefficient will be greatly reduced. When the water flow accumulates more in the main drum, the friction of the belt is insufficient to support the forward movement of the belt. At this time, the belt speed will decrease and the belt will slip.
2.The rubber coating of the main drum is damaged
Drum gluing is an important part of the belt conveying system. The drum after gluing can effectively improve the operation of the conveying system, protect the metal drum from wear, increase the surface friction between the belt and the drum, effectively prevent the sliding friction between the drum and the belt and reduce the belt slip. However, when the belt conveyor runs for many years, the rubber coating material is aged, deformed or seriously worn, the friction coefficient between it and the belt will decrease sharply, which will cause the belt to slip.
3.Insufficient belt tension
If the belt does not have enough tension, there will not be enough friction driving force between the driving wheel and the belt, and it will not be able to pull the belt and load movement.
The tensioning device of belt conveyor usually includes screw tensioning, hydraulic tensioning, heavy hammer tensioning and vehicle tensioning. Insufficient travel or improper adjustment of screw or hydraulic tensioning device, insufficient counterweight weight of heavy hammer tensioning device and vehicle tensioning device, and mechanism jamming will cause insufficient tension of belt conveyor and slip.
4.Stacking accident of head chute
After the chute at the head of the belt conveyor is stacked, if the stacking protection switch fails, more and more materials will be stacked at the head, and even the head and the nearby ground will be buried, thus crushing the belt. With the continuous movement of the main drum, the temperature of the belt in contact with it will rise sharply, and the belt can be broken in just a few minutes, which will bring great economic losses and endanger personal safety.
5.Belt conveyor overload
The slipping caused by excessive belt load is often caused by insufficient motor capacity, especially after abnormal shutdown, there are a lot of materials in the belt. Starting with load will cause great damage to the equipment and easily cause the motor to burn out. Therefore, the operator should pay close attention to the value of the belt scale and the current of the belt conveyor, control the amount of materials and avoid overload operation.
In case of heavy load shutdown, the post driver can try to start at a slow speed first and start again by inching twice to make full use of the belt inertia to overcome the slip phenomenon. However, when this operation is invalid, multiple attempts shall be avoided and the load of the belt conveyor shall be reduced by cleaning the material stored on the belt.
6.The resistance increases during belt operation
The belt conveyor will also slip if the tail drum bearing is locked or large materials enter, the upper and lower idlers of the belt conveyor are stuck, and there are foreign matters hanging on the belt in the tail chute.
The direct reason is to increase the running resistance of the belt conveyor, so that the relative displacement friction between the main drum and the belt will cause damage to the belt equipment after long-time operation.
Precautions against belt slip
1. The belt conveyor often slips, which is difficult to deal with afterwards, which seriously affects the safety production. After repeated on-site investigation and long-term market research, a factory decided to use the belt conveyor slip protection switch.
The protection master-slave probe detects the main drum, changes to the pulse frequency signal generated by the magnetic block signal generation point at the drum, and displays the corresponding speed alternately.
In case of inconsistent speed, the relay can be controlled to close within 10s to stop the belt conveyor, which effectively reduces the expansion of the accident after the belt conveyor slips.
2. Add soft start protection device for high-power belt conveyor. The soft start of the belt conveyor is that the belt conveyor gradually accelerates steplessly from static to rated speed.
Its advantage is to avoid the impact force during starting, that is, there is no impact force on the belt, motor and belt frame, especially the tension requirement of the belt is reduced, which greatly avoids the occurrence of belt slip, and can start with heavy load to reduce the starting current and impact on the power grid.
3. Ceramic coating of the main drum. The rubber plate adopts ceramic particles attached to the surface of the rubber plate, which can effectively increase the friction between the driving drum and the belt. Through the experiment, it can also be concluded that the friction coefficient of ceramic coating is 2-3 times higher than that of rubber coating.
Although the price of ceramic rubber plate is expensive, which is generally three times that of rubber plate, the service life of ceramic rubber plate is long. Generally, ordinary rubber plate has to be replaced due to rubber wear after two years of use, while ceramic rubber plate under the same working conditions can be used for more than 10 years.
4. Strengthen the implementation of production scheduling coordination and equipment maintenance system, avoid belt slip accidents caused by operation and equipment problems, and ensure safe production.