The cause of bearing ring fracture and emergency p

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Analysis on the causes of bearing ring fracture and emergency plan

ring fracture is one of the problems perplexing bearing quality, and defect fracture is the main form of ring fracture, which is mainly caused by raw material problems or improper production operation, and the equipment can not operate normally. It is analyzed as follows in combination with practice

I. raw materials

the inclusion, looseness, brittle element segregation or carbide liquidus, shape, strip, and unfortunately free of uniform segregation of raw materials have better performance defects than traditional materials. If they are not eliminated or improved in the processing, they will cause stress concentration, weaken the basic strength of the ring, and become the crack source. The preventive measures are to adhere to the main channel supply, try to purchase steel with stable and reliable quality, strengthen the warehousing inspection of purchased steel, and check from the source

II. Production and equipment

1 Forging: the toughness and strength of the ferrule will be reduced if overburning, overheating and internal cracking carbides occur during the forging process. Therefore, the processing temperature, circulating heating and heat dissipation conditions after forging (such as spray cooling) must always be strictly controlled. Especially, after the final forging of large varieties of ferrules, those whose temperature is above 700 ℃ shall not be stacked

2. Heat treatment: close monitoring of heat treatment equipment is an important work in the workshop

reliability of monitoring equipment. Important temperature control instruments such as instruments and thermocouples shall be closely monitored to ensure accurate and reliable measurement data; If the error exceeds the standard, it shall be replaced in time. It is strictly prohibited to operate with the fault

record of monitoring data. The temperature recording device of each heat treatment equipment must be restored to effectively monitor the whole process of equipment work (focusing on night shift), so as to make the heat treatment quality have strong traceability, eliminate false records and randomness, and provide complete data for ISO9000 quality system

quenching cooling conditions. In order to solve the soft spot and other defects of bearing rings of medium and large varieties, the composition and properties of quenching oil should be determined. If it does not meet the requirements, it should be replaced with rapid quenching oil to enhance the quenching ability as a medium and improve the quenching cooling conditions

strict tempering process. For the varieties with more fracture phenomena, the secondary tempering after rough grinding of the ferrule can not only further stabilize the structure and size of the ferrule, but also reduce the grinding stress and improve the performance of the grinding metamorphic layer. Recently, the secondary tempering process has been implemented for 22328/02 and 22236/02. In order to verify the pendulum impact testing machine more accurately, it needs to be verified by after-sales tracking feedback

3. Monitoring of grinding process. The finished bearing ring is not allowed to have grinding burns and grinding cracks, especially on the mating surface of the inner ring with taper change. If the ferrule is pickled, it shall be fully inspected to remove the burned products. The severely burned ones cannot be repaired or the unqualified ones shall be scrapped. The ferrule with grinding burns is not allowed to enter the assembly process

4. Identification management: after the steel is warehoused and before the ferrule grinding, each process must be strictly managed to strictly distinguish between GCr15 and GCr15SiMn materials and products

III. overload fracture and fatigue fracture of ferrule

the possibility of overload fracture and fatigue fracture of ferrule exists at the same time, especially for bearings with poor service conditions (such as 22328, etc.). The research on the fracture phenomenon of the continuous falling circle of the set cement price should not only be considered from the perspective of materials and defects generated in the production process, but also be studied and analyzed on the structural dimensions of bearing parts, processing measurement means, processing technology, bearing service conditions and other factors

1. Bearing structure and service conditions. Different structures are suitable for different service conditions; Bearing parts with different structures have different processing technologies, which will affect their quality. Therefore, we should develop new structural products to adapt to different service conditions, and indicate the appropriate service conditions or performance on the bearing instructions to facilitate the choice of customers

2. Strengthen process research, improve processing technology, improve processing quality, and reduce the possibility of defects in processing. For example, in terms of heat treatment, for the inner and outer rings of larger varieties, try to use the medium and lower quenching and heating temperature to adapt to extending the holding time to improve the alloying concentration and increase the fracture strength of martensite. On the premise of ensuring the quality, select a higher tempering temperature to enhance the impact toughness of the workpiece

3. Improve processing monitoring means to promote the improvement of processing quality. For example, how to improve the curvature position of the flow channel, but how to make waste plastic into high-quality printing material monitoring, improve the overall performance of the bearing after assembly, and improve the working condition of the bearing

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