32211/01 bearing ring fracture analysis

2020-32211/01 bearing ring fracture analysis 09 - 28 Sun Qinhe Zhang Mingdi ( Hangzhou horse bearing co. , LTD. ) Abstract: in view of the 32211/01 ring rupture problem during production, raw materials, heat treatment quality inspection analysis. 32211/01 results show that the fracture is caused by improper grinding technology of raceway surface cracks caused by the severe mesh tortoises. Find ring fracture, and analyze the reasons. The improvement measures are put forward. Key words: bearing ring, Fracture; 32211/01 bearing ring grinding burn in grinding processing, have found a woolly ring fell to the ground, broken to size 5 blocks, fractured pieces of magnetic is big, can broken small adsorption together. As shown in figure 1. Figure 1:32211/01 of the cataclastic bearing outer ring of the bearing ring production process is: the bar under the medium frequency heating - - forging molding - spheroidizing annealing - turning - quenching tempering - grinding - superfinishing. A 1, material analysis, test methods and results according to GB/T18254 - Bearing ring 2002 standard, the rupture of non-metallic inclusions and carbide irregularity examination, the results are shown in table 1, 2. Table a non-metallic inclusions, table 2, banded liquid chromatography by table 1, 2, non-metallic inclusion in the ring, carbide inhomogeneity in accordance with the requirements of GB/T182542002 standard. 2, 1) quenching tempering quality analysis , 2) hardness, As shown in figure 2, the microstructure of its images. Figure 2: metallurgical microstructure image its organization according to JB/T1255 - 2001 standard second level assessment for level 2 organization, as a qualified microstructure. 3, pickling take one piece of hot after pickling, found the net-like turtle raceway surface crack, as shown in figure 3 shows, 32211/01 fracture is caused by serious mesh turtle raceway surface crack. Figure 3: heat up the raceway surface after pickling mesh turtle crack image 2, 32211/01 mesh analysis the turtle crack formation cause the broken pieces of the raceway surface mesh turtle crack is by the grinding process is not reasonable, cause instantaneous local temperature more than Ac1, grinding surface under the action of coolant, into a secondary quenching martensite structure. Second surface due to the large temperature drop, time is short, short of Ac1 point, can only form high temperature tempering organization. It makes surface and subsurface produce a great organization stress between different organizations. The surface layer is very thin layer of hard and brittle secondary quenching martensite structure, cannot afford such a big stress. Eventually the raceway surface serious mesh turtle cracks. Results eventually lead to fracture. Three, conclusion to sum up, the 32211/01 fracture is caused by improper grinding technology of raceway surface cracks caused by the severe mesh tortoises. The fundamental to solve the problem lies in the effective control of grinding temperature. Must first have good cooling conditions, the grinding heat conduction in the time to go out, then choose suitable hardness of the grinding wheel. A final note is strictly comply with process discipline. Processed by grinding standard, put an end to savage production, to complete the production task with good quality. （ Source: the bearing failure analysis)