What are bearing ring fracture mode, do you know some? - bearing knowledge

Bearing ring fracture, common problem is the bearing network is summarized here bearing ring fracture can be analyzed from two aspects, one is the defect fracture, fracture, another is to use defect fracture mainly from raw materials and processing technology is analyzed in the process, using the fatigue fracture is the transition to wait for a reason. First, we can see the defects on bearing ring fracture reasons are: raw materials mixing, osteoporosis, brittle element segregation or carbide liquid chromatography, mesh, ribbon, not survived well and other defects in processing work together is not eliminated or improved, can cause stress concentration and weaken the ferrule basic strength, become the source of crack. Methods: preventive is insisted on a supply of main channel, and try to purchase stable and reliable quality of steel, to strengthen the incoming inspection of purchased steel, from the source the better off. Grinding process has cracks appear processing method: strengthen the monitoring of grinding process, finished goods bearing ring grinding burn and grinding cracks are not allowed to exist, especially the inner ring to change with the taper surface must not have burns. If ring should be full inspection after pickling, picking burns products, severe burns can't repair or repair the unqualified should be scrapped, grinding burn is not permitted in the ring into the assembly process. Three, improper heat treatment, the treatment is: to solve the bearing ring soft point defects such as large variety, should determine the composition and properties of quenching oil, unsuitable to advance to replacement, alternative to the rapid quenching oil, to enhance the capacity of quenching medium for hardening, quenching cooling conditions. Tempering process strictly. For fracture occurs more varieties, in the ring after coarse grinding of secondary tempering, such already can further stable organization and dimensions of the ring, can decrease again ooze grinding stress, improve grinding metamorphic layer properties. Bearing ring during use breakage phenomenon, often also mainly have three forms, respectively is: fatigue fracture, fracture and thermal overload fracture. 1, the fatigue fracture of bearing ring ( Especially outer ring) Under the alternating load and impact load, the stress incurred by the continuously exceed the material fatigue strength limit lead to the generation of fatigue crack, crack extended to a certain degree eventually lead to parts of the maximum stress fracture. Generally occur in the bearing outer ring of bearing area, due to the outer ring is usually fit for clearance fit with the bearing box holes, combined with the bearing box body is a flexible type and ellipse parts, under the alternating load and impact load easily cause fatigue fracture. 2, overload fracture is similar to fatigue fracture, used as a bearing on the stress, greater than the tensile strength of material, the inner ring crack, usually due to the improper installation, such as bearing installation tilt, causing partial load bearing, bearing local overload cause fracture cause; Other improper knock when installation causing cracking of bearing metal shed, also summarized as overload crack category. The most common interference when installation, and bearing fit size can also lead to large amount of interference of bearing ring of cracking ( There are mainly four row cylindrical bearing inner ring interference fit) , interference is too big lead to inner ring stress is larger, especially the section thickness is thinner, Thickness of section < 12 mm) Inner ring, too much interference often leads to inner ring axial crack. 3, fracture is mainly due to the thermal fracture with bearing ring end face sliding friction between parts, under the action of axial force, frictional heat, producing the end face with burns discoloration condition, such as friction and heat that causes bearing ring end face crack, crack characteristics is perpendicular to the direction of friction work, also end surface crack on thin cross section thickness ( Thickness of section < 12 mm) Within the circle of influence is bigger, especially overloaded high or medium speed mill roller bearing. Here, we must pay attention to the bearing ring fatigue fracture and overload fracture is likely to be at the same time, especially the poor service condition of bearing ( Such as 22328, etc. ) 。 Study of ring fracture phenomenon, not only from the material and production process of the defects of the Angle to think, but also the structure of bearing parts size, processing and measuring method, processing technology, through analyzing factors such as bearing service conditions. 1, the structure of the bearing and service conditions. Different structure for different service condition; Bearing parts structure different its processing technology is not the same, will affect its quality. So we should develop new product structure, to adapt to the different service condition, and can be used in bearing instructions indicated in the appropriate service condition or performance, to facilitate customer choice. 2, strengthen technology research, improve the processing technology, improve the quality of processing, reduce the potential for defects of machining. As in the heat treatment on larger varieties inside and outside the circle, as far as possible in the lower quenching heating temperature, adapt to extend the time of heat preservation, to improve the concentration of alloying, increase the fracture strength of martensite, and on the premise of guarantee quality choose the higher tempering temperature to increase the impact toughness of artifacts. 3, improve processing monitoring means, promote the quality improvement of machining. Such as improve circulation channel curvature position monitoring, improve the overall performance of the bearing is assembled, improve bearing working condition. Bearing ring fracture occurs more, has always been one of the serious problems in the quality of bearing, China bearing network share the definition of fracture under here: used as the stress on the bearing ring, is greater than the tensile strength of material or material fatigue strength limit, to cause ring crack, crack extended to a certain degree eventually lead to part of the spare parts for complete separation, called a crack or break.