1. Ensure that the conveyor belt is closely attached to the driving drum, so that its winding end has enough tension, so that the required traction can be transferred, so that the required friction between the drum and the belt, to prevent the conveyor belt from slipping.
2. Limit the tension of each point of conveyor belt to not less than a certain value, in order to prevent the belt in the roller between the excessive slack sag caused by scattering and increase the running resistance.
3. The plastic elongation of the compensation conveyor belt due to the tension and the change of elastic elongation under the transition condition.
4. Provide necessary allowance for reconnecting conveyor belt.
Layout requirements of belt conveyor tensioning device:
1. The tension device should be arranged as far as possible in the belt tension force minimum, for the length of more than 300m level or slope in 5° below the inclined belt machine, the tension device should be located close to the driving drum on the no-load branch, for short distance slope in 5° above the belt machine, the tension device should be located in the tail of the belt machine.
2. The tape should be parallel to the displacement line of the drum in and out of the branch direction of the tensioning drum, and the tensioning force should pass through the center of the drum.
Several commonly used tensioning devices of belt conveyor and their characteristics:
1. Trolley tensioning device
Is the belt conveyor tail tension drum installed on the car, the car is set to move along the horizontal or downward slope guide rail, the car through the steel wire rope and guide pulley system to hammer pull and pull the belt, using the weight of the hammer to produce tension force, can achieve the automatic adjustment of the belt, to ensure that the belt in various load state has a constant tension. The trolley type tensioning device ADAPTS to the belt conveyor is longer, the tension stroke is not limited, the power is larger, the structure is simple and reliable, but also can automatically maintain the pre-tightening force.
2. Hammer tensioning device
It is composed of two reversing drums and a tensioning drum, which can be installed in any position of the belt conveyor return tape. The tensioning drum and the sliding frame move along the vertical guide rail together under the action of a heavy hammer. Used for general belt conveyor and reversible belt conveyor, allowing a larger tension stroke, can be used for longer belt conveyor.
3. Automatic hydraulic tensioning device
It is composed of hydraulic pump station, tensioning oil cylinder, energy storage station, flam-proof and control box and five accessories. The tensioning oil cylinder is connected with the tensioning car through the movable pulley, and the steel rope is connected with the tensioning car.
(1) When starting, the tension force and the tension force during normal operation can be arbitrarily adjusted according to the needs of the belt conveyor tension, which can fully achieve the requirements of 1.4-1.5 times greater than the normal operation of the tension force during starting. Once the adjustment is made, it will work automatically according to the predetermined program to ensure that the belt works in an ideal state;
(2) Correspondingly fast, when the belt conveyor starts, the belt suddenly loosens and elongates, the machine can immediately retract the oil cylinder, timely compensate the belt elongation, small impact on the tight side, so as to make the start stable and reliable, avoid the occurrence of belt breaking accidents;
(3) It has the protection function of automatically stopping belt conveyor when the belt is broken and automatically increasing tension force when slipping;
(4) Compact structure, small installation space;
(5) It can be connected with centralized control device to realize remote centralized control of the machine and microcomputer control.