1. Belt deviation caused by installation:
The installation quality of belt conveyor has the greatest influence on belt deviation, and the belt deviation caused by installation error is the most difficult to deal with. Installation errors mainly include:
(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 driving drum or reversing drum. If it cannot be adjusted, the belt joint must be reconnected;
(2) The frame is skewed. Rack skew includes rack centerline skew and rack side tilt, both of which will cause serious deviation and are difficult to adjust. When we tested a belt conveyor installed by a non-professional installer, the belt deviated seriously. Through measurement, it is found that the center line of belt conveyor is skewed. After the head and tail are adjusted, the deviation in the middle part can't be corrected anyway. Finally, reinstall the rack to solve the problem.
(3) The rubber plates on both sides of the guide chute have uneven pressure. Due to the uneven pressure of the rubber plate, the running resistance on both sides of the belt is inconsistent, resulting in belt deviation. This situation is relatively easy to handle, as long as the pressure of rubber plates on both sides is readjusted.
2. Belt deviation caused in operation:
(1). Deviation caused by material sticking between the roller and the idler: After the belt conveyor runs for a period of time, due to the certain viscosity of copper concentrate, some mineral powder will stick to the roller and the idler, which makes the diameter of the roller or the idler locally larger, resulting in uneven tension on both sides of the belt and belt deviation.
(2) Deviation caused by belt slack. After the adjusted belt runs for a period of time, due to the permanent deformation or aging caused by belt stretching, the tension of the belt will decrease, leading to belt relaxation and belt deviation.
(3) Deviation caused by uneven distribution of mineral aggregate. If the belt does not run off during idling, it will run off during heavy load, indicating that the mineral distribution on both sides of the belt is uneven. The uneven distribution of mineral aggregate is mainly caused by the incorrect falling direction and position of mineral aggregate. If the mineral aggregate deviates to the left, the belt will deviate to the right. or vice versa, Dallas to the auditorium
(4) Deviation caused by vibration in operation. The mechanical vibration of belt conveyor in the process of operation is inevitable. The faster the belt runs, the greater the vibration and the greater the belt deviation. In the belt conveyor, the vibration caused by the radial jump of the idler has the greatest influence on the deviation of the conveyor belt.
Second, the handling of belt deviation of belt conveyor
In view of the causes of belt conveyor deviation, we have taken corresponding countermeasures to adjust. For the deviation caused by the installation error, firstly, the installation error should be eliminated, the belt joint should be reconnected, and the seriously skewed frame should be reinstalled; For the deviation in operation, our main adjustment methods are:
1. Adjust the idler assembly. When the belt of the belt conveyor deviates from the center of the whole belt conveyor, we adjust the deviation by adjusting the position of the idler group, and the installation holes on both sides of the roller bracket are machined into long holes, which is convenient for adjustment. See figure 1 for the adjustment method. The specific method is to which side the belt deviates, which side of the idler group moves forward along the running direction of the belt, and the other side moves backward. As shown in figure 1, if the belt deviates downward, the upper position of the idler gear set should move to the left and the lower position of the idler gear set should move to the right. This method can eliminate the belt deviation caused by frame skew, uneven distribution of mineral materials and vibration.
2. Install the self-aligning idler assembly. Usually, a self-aligning idler pulley group is installed every 6- 10 group. Its working principle is to automatically center the belt by blocking or preventing the idler from rotating in the horizontal plane or generating lateral thrust, 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.
3. In order to prevent deviation, a new idler gear set is adopted. The belt conveyors in our factory are mainly TD75 and Japanese belt conveyor standards. Through understanding, in the new national standard DTⅱ, the bearing idler group has a forward-leaning structure, and the empty idler group has a V-shaped structure. These two groups of idlers have a good effect on preventing the belt from running off. We introduced their structure into the existing belt conveyor, which played a very good role in preventing the deviation of the conveyor belt.
4. Adjust the positions of the driving roller and the reversing roller. The adjustment of driving roller and reversing roller is an important link in the adjustment of belt deviation. Because a belt conveyor has at least 2 to 5 rollers, the installation position of all rollers must be perpendicular to the center line of the belt conveyor in the length direction, and excessive deflection will inevitably lead to deviation. For the head drum, if the belt deviates to the right side of the drum, the bearing seat on the right side should move forward; if the belt deviates to the left side of the drum, the bearing seat on the left side should move forward. Accordingly, the adjustment method of moving the left bearing seat or the right bearing seat to the tail drum is just the opposite to that of the head drum. Because the adjustment distance of the driving drum is limited (10-30mm), in general, after the axis of the driving drum is adjusted to be perpendicular to the length direction of the belt conveyor, the position of the bearing seat of the tail drum is mainly adjusted by the screw tensioner or the heavy hammer tensioner, and it will be adjusted repeatedly until the belt is adjusted to the ideal position. This method can effectively eliminate the belt deviation caused by belt slack and frame skew.
5. Adjustment of tension. The adjustment of belt tension is a very important link in the deviation adjustment of belt conveyor. The two reversing rollers at the upper part of the tension part of the heavy hammer should be perpendicular to the vertical line of gravity in addition to the length direction of the belt, that is, to ensure that the axis line is horizontal. When using screw tensioning or hydraulic cylinder tensioning, the two bearing seats of the tensioning roller should be translated at the same time to ensure that the roller shaft 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 the belt deviation caused by belt slack and frame skew.
6. Adjustment of deviation of bidirectional belt conveyor. The deviation adjustment of bidirectional belt conveyor is much more difficult than that of unidirectional belt conveyor. In the specific adjustment, we adopted the method of adjusting one direction first and then the other. In the process of adjustment, carefully observe the relationship between belt movement direction and deviation trend, and adjust them one by one. The emphasis is on the adjustment of driving roller and reversing roller, followed by the adjustment of idler and blanking point.
In short, as long as the daily inspection is strengthened, various factors causing belt deviation are eliminated in time, and the law of belt deviation is mastered, the corresponding solutions can be found. I hope this paper can provide reference for other belt conveyor users.