Belt mistracking is one of the most common failures when belt conveyors are running. There are many reasons for mistracking, the main ones being low installation accuracy and poor daily maintenance. During the installation process, the head and tail rollers and the intermediate idler should be on the same center line as far as possible and parallel to each other to ensure that the conveyor belt is not biased or less biased. In addition, the strap joints should be correct and the circumference on both sides should be the same.
In the process of use, if there is deviation, the following checks should be made to determine the cause and make adjustments. The parts and treatment methods that are often checked when the conveyor belt deviates are:
(1) Check the non-coincidence between the transverse centerline of the roller and the longitudinal centerline of the belt conveyor. If the coincidence value does not exceed 3mm, it should be adjusted by using the long mounting holes on both sides of the idler set. The specific method is which side of the conveyor belt is deflected, which side of the idler group moves forward in the direction of the conveyor belt, or the other side moves back.
(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 move backward; If the conveyor belt deviates to the left side of the pulley, the housing on the left side of the pulley should be moved forward or the right housing should be moved backward. The tail drum is adjusted in the opposite way to the head roller.
(3) Check the position of the material on the conveyor belt. Material that is not centered on the conveyor belt cross-section will cause the conveyor belt to deviate.If the material is biased to the right, the belt is deviated to the left and vice versa. When using, the material should be centered as much as possible. In order to reduce or avoid such belt mistracking, a baffle plate can be added to change the direction and position of the material.debugging
The conveyor belt is the key equipment of the conveyor system, and its safe and stable operation directly affects the production operation. Conveyor belt deviation is the most common fault of belt conveyor, and timely and accurate treatment is the guarantee of its safe and stable operation. There are many phenomena and causes of deviation, and different adjustment methods should be adopted according to different deviation phenomena and causes in order to effectively solve the problem. Based on years of on-site practice, this paper analyzes and explains the causes and treatment methods of such faults from the perspective of users using mechanical principles.
1. The axis of the head drive drum or the tail reversing pulley is not perpendicular to the center line of the conveyor, causing the conveyor belt to deviate at the head pulley or the tail reversing drum. When the roller is deviated, the tightness of the conveyor belt on both sides of the roller is inconsistent, and the traction force Fq along the width direction is also inconsistent, and it becomes an increasing or decreasing trend, so that the conveyor belt will be attached to a moving force Fy in the decreasing direction, resulting in the conveyor belt deviating to the loose side, that is, the so-called "running loose and not tight". Its adjustment method is: for the head pulley, such as the right side of the conveyor belt to the roller, the bearing seat on the right side should move forward, and the conveyor belt deviates to the left side of the pulley, then the bearing seat on the left side should move forward, and the corresponding bearing seat on the left side can also be moved backward or the right bearing seat backward. The tail drum is adjusted in the opposite way to the head roller. After repeated adjustments, the belt is adjusted to the ideal position. It is best to install the drive or redirection drum exactly where it is before adjusting it.
2. The diameter is different due to processing errors, stickiness or uneven wear on the outer surface of the roller, and the conveyor belt will deviate to the side with a larger diameter. That is, the so-called "run big not run small". Its stress situation: the traction force Fq of the conveyor belt produces a moving component Fy to the large side of the diameter, and under the action of the component force Fy, the conveyor belt produces an offset. In this case, the solution is to clean up the sticky material on the surface of the drum, and replace the processing error and uneven wear to re-process the lagging treatment.
3. The uncorrect blanking position at the transfer point causes the conveyor belt to deviate, and the blanking position of the material at the transfer point has a very great impact on the deviation of the conveyor belt, especially when the projection of the upper conveyor and the conveyor in the horizontal plane is vertical. In general, 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 it is difficult to center the material. The material on the conveyor belt cross-section is deflected, and the horizontal component Fy of the impact force Fc eventually leads to belt misalignment. If the material is biased to the right, the belt is deviated to the left and vice versa.
For mistracking in this case, the relative height of the two conveyors should be increased as much as possible during the design process. The form and size of the upper and lower funnels, guide troughs and other parts of the belt conveyor that are limited by space should be carefully considered. Generally, the width of the guide trough should be about three-fifths of the width of the belt. In order to reduce or avoid belt deviation, the baffle plate can be added to block the material and change the falling direction and position of the material.
Fourth, the perpendicularity error between the installation position of the bearing roller group and the center line of the conveyor is large, resulting in the deviation of the conveyor belt in the bearing section. When the conveyor belt runs forward, give the roller a forward traction force Fq, this traction force is decomposed into the component force Fz that makes the roller rotate and a transverse force Fc, this transverse force makes the roller move axially, because the fixed roller of the roller bracket can not move axially, it will inevitably produce a reaction force Fy on the conveyor belt, it makes the conveyor belt move to the other side, which leads to deviation.
After figuring out the force situation when the load roller group is installed and deflection, it is not difficult to understand the reason for the deviation of the conveyor belt, and the method of adjustment is clear.
The first method is to make long holes on both sides of the idler set during manufacturing so that they can be adjusted. The specific method is which side of the belt is biased, which side of the roller set moves forward in the direction of the belt, or the other side moves back. For example, if the belt deviates in the upward direction, the lower position of the roller group should be moved to the left, and the upper position of the roller group should be moved to the right.
The second method is to install the self-aligning roller group, the self-aligning roller group has many types, such as intermediate shaft type, four-link type, vertical roller type, etc., and its principle is to use the blocking or roller to rotate in the direction of the horizontal plane to block or produce transverse thrust to make the belt automatically centripetal to achieve the purpose of adjusting the belt deviation, and its stress is the same as the deflection force of the bearing roller group. Generally, this method is more reasonable to use when the total length of the belt conveyor is short or when the belt conveyor is running in both directions, because the shorter belt conveyor is more likely to deviate and is not easy to adjust. It is best not to use this method for long belt conveyors, because the use of spherical idler sets will have a certain impact on the service life of the conveyor belt.
