中文
Treatment of deviation of conveying tape in asphalt concrete mixing equipment
Asphalt concrete mixing equipment generally adopts conveying belt conveyor to convey cold materials. Its main advantages are large conveying capacity, continuous operation, simple equipment structure and automatic control. However, belt running is a common fault, which directly affects the drying operation of drying drum and the production efficiency of mixing equipment. Therefore, it is very important to solve the problem of tape deviation in the operation site of asphalt concrete mixing equipment.
1. Deviation of tape
The belt of the conveying belt machine is a circular closed structure. In normal operation, the conveying tape operates in a circular cycle. The center lines of the upward and downward tapes are parallel to each other or in the same plane, running smoothly and without jumping phenomenon, and the offset along the width direction of the tape is less than 5% of the width of the tape; the tensile stress of the tape along its width direction is equal. When the deviation of the belt exceeds 5% of its width during the operation of the conveying belt machine, it is called belt deviation. At this time, the upward and downward tape centerlines are not parallel or in different planes, the tape tension stress along its width direction will change, and the tape tension stress on the run-off side will increase.
2. Reasons for deviation
When the belt conveyor is running, the belt contacts with the idler. The interaction force between the belt and the idler is related to the contact degree and friction coefficient of the belt and the idler in the direction of the bandwidth. If the contact degree between the belt and the idler is different along the direction of the bandwidth, the interaction force is not equal everywhere. When the supporting roll acts on the force, the supporting roll will be acted by the moment M, which makes the supporting roll rotate clockwise along the central line of the belt. However, because the supporting roll is fixed on the frame of the belt conveyor, this movement is not allowed to occur, it will lead to the belt moving to the left to balance the movement trend of the supporting roll, so the belt will run off. There are many factors that cause tape deviation. The main reasons are as follows: 1. The installation position of cold aggregate grader hopper or inclined tape machine hopper is incorrect, which results in the phenomenon of tape deviation load. (2) The manufacturing and installation quality of the frame and idler of the conveying belt conveyor is not high, which results in the force between the belt and idler varying along the direction of the belt width. (3) The bonding quality of belt conveyor is not high, resulting in uneven joints and trumpet phenomenon. (4) The performance of the tape itself is poor and the grooving property is not good, which results in the unbalanced load. _The tape was damaged locally. The above factors will lead to the change of the pull force along the width direction of the tape, and eventually make the tape move towards the side with large pull force, resulting in the deviation of the tape.
3. Correcting measures
(1) Principle of rectifying deviation
When the belt runs to the left, the left side of the idler will be inclined forward along the direction of the belt, and the friction of the idler will affect the belt. N can be decomposed into two components, i. e. the component Nx along the direction of rubber band width and the tangential component Nt that causes the rollers to rotate. Force Nx is the correcting force that makes the tape move to the right to correct the deviation.
(2) Correcting measures
(1) The flat idler is inclined forward along the running direction of the belt at the deviation side of the belt, which is generally 2-4 degrees. (2) Two sets of self-aligning trough rollers with reversible rotating frames along the length direction of the belt can automatically correct the deviation of the belt. (3) Installing a certain number of anti-deviation vertical rollers on both sides of the belt on the frame of the conveying belt conveyor to forcibly prevent the belt from deviating. (4) Surface treatment of some idlers, glue hanging treatment on the outer surface of idlers, rubber surface to enhance the anti-lateral displacement ability of rubber belt. _Using automatic deviation correction system, that is, using photoelectric technology to monitor the operation of tape conveyor. When the deviation of the tape reaches a certain position, the photoelectric switch receives the signal and sends out the signal, controls the action of the deviation correction device, and automatically corrects the deviation of the tape. At present, there are two main types of deviation correction devices: mechanical and hydraulic.