The cause and solution of the rupture of the drum of the belt conveyer
Belt conveyer is a kind of continuous movement conveying machine with belt as traction mechanism and bearing mechanism. It has large transportation capacity, low working resistance, low power consumption and simple maintenance. It has been widely used in the ground and underground transportation of coal mine. The roller is the main component of the belt conveyor. The service life of the roller seriously affects the normal operation and production of the conveyor. Starting from the analysis of the structure and stress of the drum, this paper sums up the improving method for improving the strength of the drum.
1. The structure and working principle of the drum
The roller can not only transmit traction, but also change the direction of the operation of the belt conveyor. According to the manufacturing process, it is divided into welding rollers and cast welding rollers. They are divided into driving rollers and changing cylinders according to their functions. The high power (> 360kw) drive roller adopts the cast welding roller, the rest can use the welding roller, the roller is made up of the shaft, the reel and the two disks, the plate is the casting and the drum is rolled up by the steel plate. In the work, the shaft is connected with the connecting plate, the disc is welded with the disc, the driving force is transmitted to the roller shaft, and the shaft drives the roller to move integrally so as to drive the belt to run. Its transmission theory is based on the principle of friction transmission, that is, the drive device and the conveyor belt are connected organically with the friction force between the drive cylinder and the conveyor belt to complete the energy transfer between the two and ensure the reliable operation of the conveyor.
2. Cause analysis and influencing factors of roller rupture
(1) analysis of the causes of rupture
The pressure of the belt on the roller is great. In the long term large pressure, it is easy to break the drum. The crack often is from the axial crack to the other side of the web. The main cause of rupture: first, the belt tension is big, because the tension is big, the traction force is big, the conveyor is to improve the transmission capacity. It is always hoped to use enlarging tension to achieve the purpose. This will increase the pressure of the drum. In addition, the rotating speed increases, and the torque on the roller will also increase, which will make the roller and its zero. Bending deformation, adding downhole environment, and then causing cylinder fracturing; two is not the strength of the cylinder itself, the selected steel plate material is not good or the thickness of the steel plate is not enough, will also cause rupture; three is the steel plate welding process is not good, welding quality is not high, will also cause rupture. Because the structure of the cylinder can not be separated from the welding, the welding stress will be produced during the operation. If the treatment is not good, the crack will appear in the welding place very quickly under the action of pressure.
(2) several factors affecting the rupture of the drum
The strength of the roller is reduced and the cylinder is cracked. The main influencing factors are: (1) the influence of dirt on wear. The wear and tear caused by the broken coal dust and dirt on the surface of the belt and roller are typical abrasive wear. That is, the wear and tear produced by these fragments often produce special chips and make pitting on the surface of the damaged roller, and there is a fatigue effect due to the surface impact. In addition, the chemical action of liquid or gas medium, especially the effect of high temperature, aggravates the wear and tear, which makes the strength of the drum lower, and the influence of the enclosure angle on the wear. Enlarging the enclosure angle will increase the traction force of the roller surface and reduce the wear, but the enclosure angle is not easy to oversize, otherwise it will aggravate the bending fatigue damage of the adhesive tape; thirdly, the effect of friction coefficient on wear. Increasing friction coefficient is the best way to reduce wear. At present, efforts are being made to find materials with high friction coefficient, stable performance, wear resistance and high specific pressure.
(1) choose high quality materials to improve manufacturing quality and ensure drum strength.
(2) increase the thickness of the steel plate of the drum, and evenly arrange several reinforcing bars along the inner side of the drum. According to the force of the roller, the tension of the belt around the drum can be calculated, and the stiffeners should be designed to enhance the strength of the drum.
(3) improve the welding process and ensure the quality of the welding. Welding between the disc and the cylinder is the key process for making the drum. According to the design requirements, the weld quality must reach JB1152-81 II grade standard.
The CO2 and Ar mixed gas shielded arc welding is used for backing welding, and then the submerged arc welding method is adopted. When welding, the roller is rotated on the roller frame and the speed can be controlled. When the backing welding is done, the welding torch should be manually operated. The method of one-sided welding and double face forming is used to ensure that the root of the weld can be melted and no welding defects are found. The welding of the remaining layers can be fixed on the top of the roller weld by the welding torch or the submerged arc welding machine head, and the welding automation can be realized by rotating the drum. After welding, it must be tempered. As the drum shaft has been tempered, the overall backfire of the drum will reduce the performance of the shaft. It can only handle the weld partial tempering, and uses a tracked far-infrared heater to temper the weld and eliminate the residual stress of the welding. The heater is wrapped on the weld line and covered with insulation cotton.
(4) strengthen the maintenance and improve the service life of the roller, such as keeping the working place clean, ensuring the heat dissipation, not allowing the tape to slip along the roller, finding the relaxation immediately tensioning, ensuring that the cleaning device works normally, the surface of the roller is not allowed to adhere to the sundries and so on.
(5) regular inspection and maintenance to ensure reliable operation.
(6) the surface of the roller is coated with adhesive, and the high strength and wear-resistant material such as polyamine grease is used as the liner of the roller to increase the friction between the roller and the tape, to reduce the wear and prevent the rupture and to improve the service life of the roller.
The actual use proves that the improvement measures adopted in the belt conveyor roller rupture are feasible, reasonable, reliable and practical. The cylinder is an important part of the belt conveyor. From the analysis of the force analysis of the drum, the quality of the manufacturing, especially the quality of the welding, the correct use and maintenance, is the guarantee of the quality of the drum.