How to deal with conveyor belt deviation

Reason introduction

Belt misalignment is one of the most common faults when a belt conveyor is running. There are many reasons for the deviation, the main reasons are low installation accuracy and poor daily maintenance. During the installation process, the head and tail rollers and the middle idler should be on the same center line as much as possible, and they should be parallel to each other to ensure that the conveyor belt is not deviated or less deviated. In addition, the strap joints should be correct and the circumference should be the same on both sides.

Approach

During use, if deviation occurs, the following inspections should be made to determine the cause and make adjustments. The parts and treatment methods that are often checked for conveyor belt deviation are:

(1) Check the misalignment between the lateral centerline of the idler and the longitudinal centerline of the belt conveyor. If the misalignment value exceeds 3mm, it should be adjusted using the long mounting holes on both sides of the idler set. The specific method is which side of the conveyor belt is biased, which side of the idler group moves forward in the direction of the conveyor belt, or the other side moves backward.

(2) Check the deviation value of the two planes of the head and tail frame mounting bearing seats. If the deviation of the two planes is greater than 1mm, the two planes should be adjusted in the same plane. The adjustment method of the head drum is: if the conveyor belt deviates to the right side of the drum, the bearing seat on the right side of the drum should move forward or the left bearing seat should move backward; if the conveyor belt deviates to the left side of the drum, the The bearing housing on the left side of the drum should move forward or the right bearing housing back. The adjustment method of the tail roller is just the opposite of that of the head roller.

(3) Check the position of the material on the conveyor belt. The material is not centered on the cross section of the conveyor belt, which will cause the conveyor belt to deviate.

If the material is skewed to the right, the belt is skewed to the left and vice versa. When using, the material should be centered as much as possible. In order to reduce or avoid such conveyor belt deviation, a baffle can be added to change the direction and position of the material.

debugging

The conveyor belt is the key equipment of the conveying system, and its safe and stable operation directly affects the production operation. The deviation of the conveyor belt is the most common fault of the belt conveyor, and its timely and accurate treatment is the guarantee of its safe and stable operation. There are many phenomena and reasons for deviation, and different adjustment methods must be adopted according to different deviation phenomena and reasons to effectively solve the problem. This article is based on years of field practice, from the perspective of users, using mechanics principles to analyze and explain the causes and treatment methods of such failures.

1. The axis of the head driving drum or the tail redirecting drum is not perpendicular to the center line of the conveyor, causing the conveyor belt to deviate at the head drum or the tail redirecting drum. When the drum is deflected, the tightness of the conveyor belt on both sides of the drum is inconsistent, and the traction force Fq along the width direction is also inconsistent, which is an increasing or decreasing trend, which will add a moving force Fy in the decreasing direction to the conveyor belt. , causing the conveyor belt to deviate to the loose side, that is, the so-called "running loose but not running tight". The adjustment method is as follows: for the head drum, if the conveyor belt deviates to the right side of the drum, the right bearing seat should move forward, and the conveyor belt deviates to the left side of the drum, then the left bearing seat should move forward. Move, correspondingly, the left bearing seat or the right bearing seat can also be moved backward. The adjustment method of the tail roller is just the opposite of that of the head roller. After repeated adjustment until the conveyor belt is adjusted to the ideal position. It is best to install the exact location of the drive or redirection drum before adjusting it.

2. The diameter of the outer surface of the drum is different due to processing errors, sticking materials or uneven wear, and the conveyor belt will deviate to the side with the larger diameter. This is the so-called "run big and not run small". Its force condition: the traction force Fq of the conveyor belt generates a moving component force Fy to the larger diameter side, and the conveyor belt is offset under the action of the component force Fy. In this case, the solution is to clean up the sticky material on the surface of the drum, and the processing error and uneven wear should be replaced and reprocessed.

3. The position of the material at the transfer point is not correct, causing the conveyor belt to deviate. The position of the material at the transfer point has a great influence on the deviation of the conveyor belt, especially when the upper conveyor and this conveyor are projected on the horizontal plane. The effect is greater when vertical. Generally, the relative height of the upper and lower belt conveyors at the transfer point should be considered. The lower the relative height, the greater the horizontal velocity component of the material, the greater the lateral impact force Fc on the lower belt, and the material is also difficult to center. To deflect the material on the cross section of the conveyor belt, the horizontal component Fy of the impact force Fc eventually causes the belt to deflect. If the material is skewed to the right, the belt is skewed to the left and vice versa.

For the deviation in this case, the relative height of the two conveyors should be increased as much as possible in the design process. The form and size of the upper and lower hoppers, guide troughs and other parts of the belt conveyor that are limited by space should be carefully considered. Generally, the width of the guide groove should be about three-fifths of the belt width. In order to reduce or avoid the belt deviation, a baffle plate can be added to block the material and change the falling direction and position of the material.

4. The verticality error between the installation position of the bearing roller group and the center line of the conveyor is large, which causes the conveyor belt to deviate in one direction in the bearing section. When the conveyor belt runs forward, a forward traction force Fq is given to the idler. This traction force is decomposed into a component force Fz that makes the idler rotate and a lateral force Fc. This lateral force causes the idler to move axially. The fixed idler of the bracket cannot move axially, and it will inevitably generate a reaction force Fy on the conveyor belt, which makes the conveyor belt move to the other side, resulting in deviation.

It is not difficult to understand the reason for the deviation of the conveyor belt, and the adjustment method is also clear.

The first method is to machine the mounting holes on both sides of the idler group into long holes for adjustment. The specific method is which side of the belt is biased, which side of the idler group moves forward in the direction of belt advancement, or the other side moves backward. For example, if the belt deviates in the upward direction, the lower position of the idler group should move to the left, and the upper position of the idler group should move to the right.

The second method is to install the self-aligning idler set. There are many types of self-aligning idler sets, such as intermediate shaft type, four-link type, vertical roller type, etc. The principle is to block or block the idler from rotating in the horizontal plane. Or generate lateral thrust to make the belt automatically centripetal to adjust the belt deviation, and its force is the same as the deflection force of the bearing idler group. Generally, it is more reasonable to use this method when the total length of the belt conveyor is short or when the belt conveyor runs in both directions, because the shorter belt conveyor is easier to deviate and is not easy to adjust. The long belt conveyor is best not to use this method, because the use of the self-aligning idler group will have a certain impact on the service life of the conveyor belt.