Conveyor belt is the key equipment of conveying system, and its safe and stable operation directly affects the production operation. The deflection of conveyor belt is the most common fault of belt conveyor, and its timely and accurate treatment is the guarantee of its safe and stable operation. There are many phenomena and reasons for deflection, and different adjustment methods should be adopted according to different deflection phenomena and reasons in order to solve the problem effectively.

Deflection solution

This paper is based on many years of field practice, from the user's point of view, the use of mechanical principles to analyse and explain the causes of such failures and methods of treatment.

First, the bearing roller group installation position and conveyor centre line of the verticality of the error is large, resulting in the conveyor belt in the bearing section to a deviation. As shown in Figure 1, the conveyor belt running forward to the rollers of a forward traction Fq, this traction force is decomposed into the rollers of the rotation of the force Fz and a transverse force Fc, the transverse force to make the rollers of the axial scurrying, due to the rollers bracket fixed rollers can not be axial scurrying, it will inevitably be on the conveyor belt to produce a reaction Fy, which makes the conveyor belt to the other side of the movement, which led to the deviation.

Figure out the load bearing roller group installation deflection force situation, it is not difficult to understand the reasons for the conveyor belt deflection, the adjustment method is also clear.

 The solution of conveyor belt deflection

The first method is in the manufacture of roller group on both sides of the mounting holes are processed into long holes, in order to adjust. Specific method is which side of the belt bias, which side of the roller group towards the forward direction of the belt forward, or the other side of the back. As shown in Figure 2, the belt upward direction of the deviation of the lower position of the roller group should be moved to the left, the upper position of the roller group to move to the right.

The second method is to install the centring roller group, centring roller group has many types such as the middle shaft type, four link type, vertical roller type, etc., the principle is to use the blocking or rollers in the horizontal plane direction of the rotation blocking or transverse thrust to make the belt automatically centring to adjust the belt deflection to achieve the purpose of the force and the bearing roller group deflection of the same force situation. Generally, it is more reasonable to adopt this method when the total length of belt conveyor is shorter or when the belt conveyor is running in both directions, because it is easier to run out of belt deflection for shorter belt conveyor and it is not easy to adjust. It is better not to use this method for long belt conveyor, because the use of centring roller set will have some influence on the service life of conveyor belt.

The axis of the head driving roller or the tail reversing roller is not perpendicular to the centre line of the conveyor, which causes the conveyor belt to run out of alignment at the head roller or the tail reversing roller. When the roller is skewed, the elasticity of the conveyor belt on both sides of the roller is inconsistent, and the traction force Fq along the width direction is inconsistent, and becomes an increasing or decreasing trend, which will make the conveyor belt additional to a decreasing direction of the mobile force Fy, resulting in the conveyor belt to the loose side of the deflection, that is, the so-called "running loose but not running tight". The adjustment method is as follows: for the head roller, if the conveyor belt deflects to the right side of the roller, the bearing seat on the right side should be moved forward, and if the conveyor belt deflects to the left side of the roller, the bearing seat on the left side should be moved forward, and the bearing seat on the left side can be shifted backward, or the bearing seat on the right side can be shifted backward. The adjustment method of the tail roller is just opposite to that of the head roller. After repeated adjustments until the conveyor belt is adjusted to a more ideal position. It is better to install the position accurately before adjusting the driving or redirecting roller.

Third, the outer surface of the roller processing errors, sticky material or uneven wear caused by the size of the diameter is not the same, the conveyor belt will run to the side of the larger diameter. That is, the so-called "run big not run small". The force situation is shown in Figure 4: the traction force Fq of the conveyor belt produces a large diameter to the side of the moving part of the force Fy, under the action of the part of the force Fy, the conveyor belt to produce offset. For this situation, the solution is to clean up the surface of the roller sticky material, processing errors and uneven wear should be replaced down to reprocessing the roller cover rubber processing.