1. Bearing quality
The service life of the roller mainly depends on the performance of the bearing and sealing. If the bearing and sealing performance of the roller is good, the service life of the roller will be greatly extended. The test results show that the friction resistance of the bearing accounts for about 1/4~1/8 of the rotation resistance of the idler. At present, the bearing models adopted by the idler are 6204KA, 6205KA, 6305KA, 6306KA and other rolling bearings. Generally, the analysis of domestic and foreign bearings shows that domestic bearings are basically the same as developed countries in terms of machining accuracy and material heat treatment.
The quality of the bearing determines the operating life. At present, a considerable number of manufacturers choose low-priced, low-quality bearings to assemble rollers, whose inner and outer diameter dimensional accuracy, hardness and clearance are not up to the technical standards. Therefore, it is necessary to purchase reliable products from domestic authentic bearing manufacturers, such as Wafangdian Bearing Company and Luoyang Bearing Company.
2. The quality of the bearing cup
Poor machining accuracy of the inner hole of the bearing cup causes the bearing to move in the circumferential direction of the bearing cup, which is one of the reasons for the damage to the roller.
Pressing the bearing cups and 3 sets of stamping dies to complete the finished product. The quality of the stamping die determines the quality of the bearing cup, it also determines the life of the bearing, and ultimately the life of the roller. Therefore, the roller manufacturer must follow-up and perform management reviews to ensure that it is a qualified purchase control list and inspect the purchased bearing cups in strict accordance with the inspection procedures.
3. Welding of bearing cup and roller tube body
The welding quality between the bearing cup and the tube body is poor, causing axial separation or dust and water infiltration into the roller bearing, causing damage to the roller. Therefore, the welding of the bearing cup and the tube body must be included in the special process and key process in the production and processing flow chart of the idler. The operating instructions for this process are specially formulated, and argon or CO2 gas shielded welding should be selected for welding. The operating instructions clearly specify parameters such as welding voltage, welding current, air flow, wire feeding speed, and tube body selection line speed. Verification and calibration are required for welding equipment, welding wire materials and welding operators. In summary, the welding of the bearing cup and the pipe body should be controlled as a special process point, and special process operation instructions should be compiled.
4. Selection of grease
Inappropriate selection of grease will cause bearing damage, which in turn will cause damage to the roller. The MT821-2006 coal industry standard clearly requires the selection of 3# lithium base grease, and all manufacturers must comply with it. Otherwise, the roller will be damaged after a few hours of operation.
The emphasis here is: For roller bearings operating at -25°C, a special type of low temperature resistant aviation grease must be selected.
5. Roller assembly
Roller assembly must not only produce special process equipment, but also must be completed on the roller press. Only in this way can the axial specified assembly pressure of the bearing, seal assembly and retaining ring be controlled. It is also required that the constructor must pass the technical training examination and pass the assembly fitter to operate. In summary, the roller assembly should be controlled as a key process point, and work instructions for key processes should be compiled.