Causes and Countermeasures bearing rings fracture
First, the raw material
Raw material inclusions, loose, brittle carbide liquation or segregation, mesh, ribbon, even when not spared segregation and other defects not be eliminated or improved processing ministry, will cause stress concentration, undermine the basic strength of the ferrule, become crack source. Preventive measures are adhere to the main channel supplier, try to purchase reliable quality steel, strengthen the purchase of steel storage inspection, from the source to good relations.
Second, the production and equipment
1. Forging: Forging process, if produced a burning, overheating, and other internal split into network carbide rings will reduce the toughness and strength. We must always be strictly controlled processing temperature cycles of heating and cooling after forging conditions (such as spray cooling), etc., in particular, to a large variety ferrule after the final forging, at temperatures above 700 ℃, shall not be stacked display.
2. Heat treatment: heat treatment equipment is closely monitoring the work of an important workshop.
Monitoring the reliability of the equipment. To instrumentation, thermocouple temperature control and other important instruments should be closely monitored to ensure accurate and reliable measurement data; excessive error to be replaced, prohibited ill run.
Record monitoring data. Must restore each heat treatment temperature recording device means for the whole process of equipment (night shift focus) Industrial effective monitoring, the heat treatment quality with strong traceability, eliminate false records and randomness, while providing complete for the ISO9000 quality system The data sheet.
Quenching conditions. To solve the large variety bearing rings soft spots and other defects, should be determined quenching oil composition and properties, and to pre-order to replace the non-conforming to the rapid quenching oil substitute, for the media to enhance the quenching hardenability capacity, improve quenching conditions.
Strict tempering process. More varieties occur against breakage, in the ring after his kibble secondary tempering, both to further stabilize the organization and the size of the ring, but also reduce Qin grinding stress, grinding deterioration layer to improve performance. Second tempering process has been implemented recently to 22328/02 and 22236/02 two varieties, pending sales tracking feedback verification.
3. The grinding process monitoring. Finished bearing rings are not allowed grinding burn and grinding cracks exist, especially with the inner surface of the screwdriver may not have burns. If the pickling should be carried out after the ferrule full inspection, product excised burns, severe burns can not be repaired or repair defective should be scrapped, they are not allowed into the grinding burn ferrule assembly process.
4. Identify the management, after grinding steel storage to the front ferrule, each step must be strictly managed, strictly distinguish between two different materials GCr15 and GCr15SiMn materials and products.
