During the operation of the belt conveyor, the phenomenon that the centerline of the tape deviates from the centerline of the belt conveyor protection devices and goes to one side is called deflection. Due to the tape deflection may cause the edge of the tape and the frame to wear each other, so that the edge of the tape is damaged and the service life is shortened. When the deflection is serious, the tape will be detached from the rollers and fall down, resulting in major accidents in the operation of the belt conveyor. The fundamental reason for the deflection of conveyor tape is that the combined force on the tape width direction is not zero or the tensile stress perpendicular to the tape width direction is not uniform and caused by the tape. Therefore, in the installation, adjustment, operation and maintenance of the belt conveyor should pay special attention to the running status of the tape, to prevent the tape deflection caused by accidents.

First, the impact of mobile belt deflection of the internal factor analysis

Belt running process affects the belt machine deflection of more factors, but the root cause is due to the uneven force of the tape inherent factors.

1, the structure of the tape and manufacturing quality is the determining factor. For example, if the core of the tape is unevenly loaded in the manufacturing process, the deviation phenomenon may occur in the operation. Another example is that the joint of the tape is not correct, i.e. the interface is not perpendicular to the centerline of the tape, resulting in uneven force on the tape, which makes the tape deflection phenomenon.

2, the installation quality and adjustment of the rollers and pulleys also have a great influence on the belt conveyor deflection. Installation of the belt machine requires straight, must ensure that the axis of each roller, each roller axis with the center line of the belt machine perpendicular to each other. Otherwise, it will make the tape in operation by the lateral thrust and the phenomenon of deflection.

3, sweeping and loading work on the belt conveyor deflection also has a certain impact. If the cleaning effect is not good, resulting in coal dust bonded to the drum, so that the radius of the drum is not equal, resulting in uneven force on the tape. When transferring the cargo load to one side, or from side to side impact on the tape caused by uneven force on the tape. All of these will cause the tape to run off. Therefore, we must pay attention to check whether the cleaner is intact and effective, and whether the load is symmetrical to the centerline of the tape.

Second, the basic law of the belt machine run off

1, run tight not run loose: tape machine transport process, if the front and rear roller center line is not parallel, resulting in tape on both sides of the degree of tension is not the same, then the tape to the tight side of the movement;

2, run high not run low: support rollers are not in the same horizontal position parallel to the running direction of the tape but one end is high and one end is low, then the tape will move to the high end;

3、Running back but not running forward: the support roller is not in the section perpendicular to the running direction of the tape, but one end of the front, one end of the back (according to the running direction of the tape), then the tape will move to the back end.

Third, for the mobile belt deflection processing method

  Adjustment of belt conveyor deflection should be carried out during no-load operation. Generally start from the head unloading pulley, along the tape running direction, first adjust the empty section, then adjust the carrying section. When adjusting, should be adjusted on one side, do not adjust both sides at the same time, and the amplitude of one adjustment can not be too large, according to the tape running situation appropriate adjustment. There are many reasons for tape deflection, which need to be dealt with differently according to different reasons. According to the author's experience in using belt conveyor safety devices, I have accumulated and summarized some treatment methods of belt conveyor deflection, which are briefly introduced as follows for reference.

1、Bearing roller adjustment method

Belt machine tape in the middle of the deviation, you can adjust the position of the roller group to adjust the deviation; in the manufacture, the roller frame on both sides of the mounting holes are processed to grow holes in order to adjust the tape upward direction deviation, the lower position of the roller group should be moved to the left, or the upper position of the roller group to move to the right.

2、Roller deviation adjustment method

The adjustment of driving roller and reversing roller is an important part of belt machine deflection adjustment. The installation position of all the pulleys must be perpendicular to the center line of the belt conveyor, if the deflection is too large, deflection is bound to occur. The adjustment method is similar to the adjustment of the roller group. For the reversing pulley such as tape to the right side of the pulley deflection, the right side of the bearing seat should be moved forward, tape to the left side of the pulley deflection, the left side of the bearing seat should be moved forward, corresponding to the right side of the bearing seat can also be moved back.

3、Correcting roller deflection adjustment method

Drum outer surface processing error, wear and tear uneven or drum outer surface sticky coal and other attachments, resulting in the diameter of the size of the tape will run to the side of the larger diameter deviation. That is the so-called "run big not run small". For this situation, the solution is to replace the drum or clean up the surface of the drum sticky coal and other adherents, to eliminate the deviation.

4, load drop correction method

The position of the drop point of the cargo load at the transfer point is not correct, resulting in tape deflection. Cargo load at the transfer point of the drop position point of the tape has a very big impact on the deviation, especially in the transfer machine and speed switch for belt conveyor overlap. If the cargo load deviates to the right side, the tape will run to the left side, and vice versa. In order to reduce or avoid the deviation of the tape, can increase the baffle plate to block the material, change the falling direction and position of the cargo load, so that the cargo load as far as possible fall in the middle of the tape position.

5、Tape and joint correction method

The tape itself, a situation is the tape use time is long, produce aging deformation, edge wear, or tape damage after the re-creation of the center of the joint is not correct, these will make the tape on both sides of the tensile force is not consistent and lead to deflection. In this case, the whole length of the tape will be deflected to one side, the maximum deflection in the incorrect joints, the only way to deal with the center of the tape joints are incorrectly re-produced, tape aging and deformation to be replaced. Another situation is the tape into the groove type difference, resulting in the tape and roller group point contact, resulting in tape deflection, this case of the tape on the whole length of the left and right deflection, the treatment method: one is to change the middle of the rollers of the groove angle; the second is the heavy load deflection adjustment.

6、Moderate tension adjustment method

The tension of the belt machine is not enough, the belt machine will not deviate when there is no load or a small amount of load, and the deviation phenomenon will occur when the load is a little big. Tensioning device is to ensure that the tape always maintains sufficient tension effective device, tension is not enough, the stability of the tape is very poor, the greater the impact of interference by external forces, and in serious cases will produce slip phenomenon. For the use of winch tensioning or hydraulic tensioning belt conveyor can be adjusted to increase the tensioning stroke to eliminate the deflection.

7、Bracket correction method

If the tape running, to the same side of the deflection and in a position more serious, that the roller bracket or rack is not correct, should be corrected bracket diagonal or rack level and verticality, replacement of serious distortion of the roller bracket. When installing the rack, the rack is not correct, which will easily cause the upper and lower tape to run in different directions.

8、Pad height adjustment method

If the tape idling always to a certain side of the deflection, can be relative to the other side of the H bracket appropriate cushion, before and after the cushion high groups to the first cushion up to the rollers shall prevail, slowly reduce the height of the cushion up, the tape deflection will disappear.