① The rivet material was changed from ML15 material to stainless steel material 12Cr18Ni9 with better durability. The mechanical properties of 12Cr18Ni9 steel wire material were increased in the new standard, from 490~830MPa to 620~880MPa, and its tensile strength increased significantly. In order to further improve the strength of the rivet material, so as to make it safer. It not only meets the requirements of standard acquisition, but also further improves the strength limit of materials, which is more conducive to improving the design and use margin of rivets.
② According to the stress analysis results of the cage and the rivet, the stress of the rivet is greatly affected by the large gap or large interference between the rivet and the rivet hole. Theoretically, there is an optimal fit amount of 0~0.02mm in the fit tolerance range, which can make the stress of the rivet relatively small. According to this principle, the diameter of the rivet rod and the diameter of the rivet hole are sorted according to the reasonable tolerance requirements, At the same time, when processing the rivet hole, prepare the cage rivet hole according to the sorting group of the rivet rod, so that the rivet and the rivet hole are in a reasonable fit range. Because the rivet and the rivet hole are not processed by grinding, and are all slender rods, the actual fit size is difficult to meet the requirements of the best fit clearance of 0 mm – clearance of 0.02 mm. From the stress analysis results, as long as the fit amount does not appear the maximum clearance and maximum interference, Although the stress of the rivet is relatively increased, the relative optimum fit is still within the safe range that the material strength can bear. According to the subsequent simulation calculation and analysis, the rivet fit is controlled by 0.03mm clearance and 0.01mm interference, which can also meet the design requirements. In order to facilitate the processing of rivet holes, rivet rod diameters are grouped according to different size deviations. Control the fit clearance between rivet and rivet hole: clearance 0.03mm – interference 0.01mm;
③ The work preparation before riveting is adopted. First, before electric riveting, adjust the positioning of the electric riveting machine tool with the mold, align the upper riveting nest and the lower riveting nest to make them concentric, adjust the riveting stroke and riveting height, and adjust the machine tool voltage to the appropriate value. The second is to install the rivet into the cage rivet hole from the non-literal face of the collar, install the rivet into the cage rivet hole and fit it with the cage end face. Third, the first piece of each batch of bearings must be empty riveted and inspected before assembly to verify the quality of the bearing related accessories and riveting tools, and the rivet assembly can be carried out after the overhead riveting inspection is qualified. The fourth is the first piece production. Put rivets on the assembled bearing cage, knock the original nail head tightly and fit it with the end face of the cage, and then rivet it. During riveting, heat the rivet rod head at the riveting position to conduct hot riveting. Each rivet is riveted separately, and each rivet is riveted diagonally and crosswise. After riveting, 100% appearance inspection shall be carried out on the rivet heads at both ends. The rivet heads and the end face of the cage shall be fitted together, and there shall be no gap or missing nail holes. Conduct self-inspection after demagnetization and cleaning of the first riveted bearing. There shall be no gap between the rivet head and the cage. The height and diameter of the rivet head shall be inspected, the appearance quality of the rivet head shall be inspected, and the rotation flexibility of the bearing shall be inspected. The bearing shall be subject to no less than 50 hours of tester performance test (overload, heavy load, light load and lubricating oil interruption conditions), 500 hours of durability test of the tester, and long-term test run assessment with the engine life. Therefore, the improvement measures are concrete and feasible.