Causes and treatment of belt deviation of belt conveyor
DT II and TD75 belt conveyors are widely used in metallurgy, mining, coal, port, transportation, water and electricity, chemical industry and other departments due to their advantages of large conveying capacity, simple structure, convenient maintenance, low cost, and strong versatility. They are used to load, ship, transfer or stack various bulk materials or pieces of goods with a loose density of 500~2500 kg/m3 under various normal temperature conditions. Materials are transported by single or multi-unit synthetic transportation system, According to the process requirements, it can be arranged in horizontal or inclined form. In addition to meeting the requirements of horizontal or inclined conveying, DT II belt conveyor can also adopt the conveying form of combination of convex arc section, concave arc section and straight line section. The allowable material block size of the conveyor depends on the belt width, belt speed, slot angle and inclination, It also depends on the frequency of the occurrence of bulk materials. The applicable working environment temperature of the conveyor is generally - 25~+40 ℃. Our company also produces light belt conveyor and mobile conveyor.
1. Reasons for belt deviation:
1.1 Belt deviation caused by installation: the installation quality of the belt conveyor has the greatest impact on the belt deviation, and the belt deviation caused by installation error is the most difficult to handle. The installation error is mainly:
1.1.1 The conveyor belt joint is not straight. The tension on both sides of the belt is uneven, and the belt always deviates to the side with high tension. In view of this situation, it can be eliminated by adjusting the tension on both sides of the drive pulley or the steering pulley. If the tension cannot be adjusted, the belt joint must be reconnected;
1.1.2 The rack is skewed. The rack skew includes the skew of the center line of the rack and the skew of both sides of the rack, both of which can cause serious deviation and is difficult to adjust. When we tested a belt conveyor installed by a non-professional installer, the belt deviation was serious. Through measurement, we found that the central line of the belt conveyor was skewed. After the head and tail were aligned, the deviation of the middle part could not be corrected in any case. Finally, reinstall the rack to solve the problem.
1.1.3 The pressure of rubber plates on both sides of the guide chute is uneven. Due to the uneven pressure of the rubber plate, the running resistance on both sides of the belt is inconsistent, resulting in the belt deviation. This situation is relatively easy to deal with, as long as the pressure of the rubber plate on both sides is readjusted.
1.2 Belt deviation caused by operation:
1.2.1 Deviation caused by sticking of roller and idler: after the belt conveyor has been running for a period of time, because the copper concentrate has a certain viscosity, part of the ore powder will stick to the roller and idler, making the local cylinder diameter of the roller or idler larger, causing uneven tension on both sides of the belt, resulting in belt deviation.
1.2.2 Deviation caused by belt slack. After the adjusted belt has been running for a period of time, due to the permanent deformation or aging of the belt stretching, the tension of the belt will be reduced, resulting in the belt relaxation and the belt deviation.
1.2.3 Deviation caused by uneven distribution of mineral aggregate. If the belt does not deflect when idling, it will deflect when running under heavy load, which means that the mineral material is not evenly distributed on both sides of the belt. The uneven distribution of ore material is mainly caused by the incorrect falling direction and position of ore material. If the ore material is to the left, the belt will run to the right; vice versa.
1.2.4 Deviation caused by vibration during operation. The mechanical vibration of the belt conveyor during operation is inevitable. When the belt runs faster, the greater the vibration, the greater the belt deviation. In the belt conveyor, the vibration caused by the radial runout of the idler has the greatest impact on the belt deviation.
2. Treatment of belt deviation of belt conveyor According to the cause of belt deviation, we have taken corresponding countermeasures to adjust it. For the deviation caused by installation error, first of all, we should eliminate the installation error. For the reconnection of the belt joint, we must reinstall the seriously skewed frame; Our main adjustment methods for running deviation are as follows:
2.1 Adjust the idler group. When the belt of the belt conveyor deviates in the middle of the whole belt conveyor, we adjust the position of the idler group to adjust the deviation. The installation holes on both sides of the idler bracket are processed into long holes, which is convenient for adjustment. The specific method is which side of the belt deviates, which side of the idler group moves forward towards the belt running direction, or the other side moves backward. As shown in Figure 1, if the belt deviates in the downward direction, the upper position of the idler group should move to the left and the lower position of the idler group should move to the right. This method can eliminate belt deviation caused by frame skew, uneven distribution of ore and vibration.
2.2 Install the automatic centering idler group. The automatic centering idler group is generally installed every 6-10 groups, and its working principle is to block or generate transverse thrust to make the belt automatically centripetal, so as to adjust the belt deviation. This method can prevent belt deviation caused by various reasons, but sometimes the effect is not very good.
2.3 The new idler group is used to prevent deviation. Our factory's belt conveyor is mainly TD75 type and Japanese belt conveyor standard. Through understanding, in the new national standard DT II type, there is a forward tilt structure for the bearing idler group and a V-type structure for the no-load idler group. These two types of idler groups have a good effect on preventing belt deviation. We introduced their structure into the existing belt conveyor for use, which has played a good role in preventing belt deviation.
2.4 Adjust the position of the drive pulley and the steering pulley. The adjustment of the drive pulley and the steering pulley is an important part of the belt deviation adjustment. Because a belt conveyor has at least 2 to 5 rollers, the installation position of all rollers must be perpendicular to the centerline of the belt conveyor in the length direction. If the deviation is too large, it will inevitably lead to deviation. For the head pulley, if the belt deviates to the right side of the pulley, the bearing seat on the right side should move forward; if the belt deviates to the left side of the pulley, the bearing seat on the left side should move forward, and the corresponding bearing seat on the left side or the right side can also move back. The adjustment method of the tail drum is just opposite to that of the head drum. The adjustment method is shown in Figure 2. Because the adjustment distance of the drive drum is limited (10-30mm), in general, after we adjust the axis of the drive drum to be perpendicular to the length direction of the belt conveyor, we mainly use the screw tensioning device or the heavy hammer tensioning device to adjust the position of the bearing seat of the tail diversion drum, which needs to be adjusted repeatedly until the belt is adjusted to the ideal position. This method can effectively eliminate belt deviation caused by belt slack and frame skew.
2.5 Adjustment of tension. The adjustment of belt tension is a very important part of the belt conveyor deviation adjustment. In addition to being perpendicular to the belt length direction, the two reversing rollers at the upper part of the heavy hammer tension shall also be perpendicular to the gravity vertical line, that is, to ensure that its axis centerline is horizontal. When screw tensioning or hydraulic cylinder tensioning is used, the two bearing seats of the tensioning roller shall be translated at the same time to ensure that the roller axis is perpendicular to the longitudinal direction of the belt. The specific adjustment method of belt deviation is similar to the adjustment at the drum. This method can effectively eliminate belt deviation caused by belt slack and frame skew.
2.6 Adjustment of deviation of two-way belt conveyor. The adjustment of belt deviation of two-way belt conveyor is relatively more difficult than that of one-way belt conveyor. In specific adjustment, we adopted the method of adjusting one direction first, and then adjusting the other direction. During adjustment, carefully observe the relationship between the belt movement direction and the deviation trend, and adjust one by one. The focus is on the adjustment of the drive drum and the diversion drum, followed by the adjustment of the carrier roller and the adjustment of the material falling point