Reason introduction
Belt deviation is one of the most common faults when belt conveyor is running. There are many reasons for deviation, the main reasons are low installation accuracy and poor daily maintenance. In the process of installation, the head and tail rollers and intermediate idlers should be on the same center line as far as possible, and they should be parallel to each other, so as to ensure that the conveyor belt is not biased or less biased. In addition, the belt joint should be correct, and the perimeter of both sides should be the same.
processing method
In the process of use, if there is deviation, the following inspection should be carried out to determine the cause and make adjustment. Conveyor belt deviation often check the parts and treatment methods are as follows:
(1) Check the misalignment between the transverse center line of idler and the longitudinal center line of belt conveyor. If the non coincidence value exceeds 3mm, it should be adjusted by using the long mounting holes on both sides of the idler group. The specific method is which side of the conveyor belt, 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 mounting bearing seat of the head and tail frames. If the deviation of two planes is greater than 1 mm, the two planes should be adjusted in the same plane. The adjustment method of the head roller is: if the conveyor belt deviates to the right side of the roller, the bearing seat on the right side of the roller should move forward or the bearing seat on the left side should move backward; If the conveyor belt deviates to the left side of the drum, the bearing seat on the left side of the drum should move forward or the bearing seat on the right side should move backward. The adjustment method of tail roller is just opposite to that of head roller.
(3) Check the position of the material on the conveyor belt. If the material is not centered on the cross section of the conveyor belt, it will lead to the deviation of the conveyor belt.
If the material deviates to the right, the belt will deviate to the left, and vice versa. In use, the material should be centered as much as possible. In order to reduce or avoid the deviation of the conveyor belt, the baffle plate can be added to change the direction and position of the material.
debugging
Conveyor belt is the key equipment of conveying system, its safe and stable operation directly affects the production operation. 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, so we should take different adjustment methods according to different phenomena and causes of deviation to solve the problem effectively. This article is based on many years of field practice, from the user's point of view, using the principle of mechanics to analyze and explain the causes of such failures and treatment methods.
1、 The axis of the head driving roller or the tail turning roller is not perpendicular to the conveyor center line, which causes the conveyor belt to deviate at the head roller or the tail turning roller. When the roller is deflected, the tension of the conveyor belt on both sides of the roller is not consistent, and the traction force FQ along the width direction is not consistent, which shows an increasing or decreasing trend. In this way, the conveyor belt will be added with a moving force FY in the decreasing direction, which will lead to the belt running deviation to the loose side, that is, the so-called "loose running but not tight running".
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; if the conveyor belt deviates to the left side of the drum, the left bearing seat should move forward; correspondingly, the left bearing seat or the right bearing seat can be moved backward. The adjustment method of tail roller is just opposite to that of head roller. After repeated adjustment until the conveyor belt to the ideal position. Before adjusting the driving or reversing roller, it is better to accurately install its position.
2、 The roller outer surface processing error, sticking or uneven wear result in different diameters, and the conveyor belt will deviate to the side with larger diameter. That is the so-called "run big or not run small". The force situation is shown in Figure 4: the traction force FQ of the conveyor belt produces a moving component FY to the large diameter side. Under the action of the component FY, the conveyor belt deflects. For this case, the solution is to clean up the surface of the drum sticking, processing error and uneven wear will be replaced, re processing package treatment.
3、 The deviation of the conveyor belt is caused by the incorrect position of the unloading at the transfer point. The unloading 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 the conveyor are projected vertically on the horizontal plane. Generally, the relative height of the upper and lower belt conveyors at the transfer point should be considered. The lower the relative height is, the greater the horizontal velocity component of the material is, the greater the lateral impact force FC on the lower belt is, and the material is difficult to center.
The horizontal component FY of impact force FC will eventually lead to belt deviation. If the material deviates to the right, the belt will deviate 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 upper and lower funnels and guide grooves of belt conveyor limited by space should be seriously considered. Generally, the width of the guide groove should be about three fifths of the belt width. In order to reduce or avoid belt deviation, a baffle plate can be added to block the material and change the falling direction and position of the material.
4、 The perpendicularity error between the installation position of the carrying idler group and the central line of the conveyor is large, which leads to the deviation of the conveyor belt in the bearing section. When the conveyor belt runs forward, it gives the idler a forward traction force FQ, which is decomposed into a component force FZ and a transverse component force FC to make the idler rotate. This transverse component force makes the idler move axially. Because the idler bracket is fixed, the idler cannot move axially, it will inevitably produce a reaction force FY on the conveyor belt, which makes the conveyor belt move to the other side, This leads to the deviation.
It is not difficult to understand the reasons for the belt deviation and the adjustment method after making clear the stress situation of the load-bearing idler group during installation deviation.
The first method is to process long holes on both sides of the idler group for adjustment. The specific adjustment method is which side of the belt, which side of the idler group moves forward towards the belt, or the other side moves backward. As shown in Figure 2, 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 group. There are many types of self-aligning idler group, such as intermediate shaft type, four-bar type, vertical roller type, etc. its principle is to use the blocking or idler to rotate in the horizontal plane to block or generate transverse thrust to make the belt automatically centripetal to achieve the purpose of adjusting the belt deviation. Its stress condition is the same as that of the bearing idler group.
Generally, this method is more reasonable when the total length of belt conveyor is short or the belt conveyor runs in two directions, because the shorter belt conveyor is easier to deviate and is not easy to adjust. And the long belt conveyor had better not use this method, because the use of self-aligning idler group will have a certain impact on the service life of the conveyor belt.
