Crack reason for spherical roller bearing and bearing carbide network defect analysis

Self-aligning ball bearing is common in machinery and equipment, the following the Chinese bearing network ( Hereinafter referred to as:) To share a common spherical roller bearing mechanical equipment run time have been seriously damaged the topography, and analyze the causes of failure of the spherical roller bearing fault. The self-aligning ball bearing main fault is the production of bearing crack and the defects of carbide network. 1, spherical roller bearing damage morphology figure introduces the spherical roller bearing result in serious damage in the process of operation, the surface of the inner ring for severe burns, eventually lead to bearing failure, cannot be used. Figure 1 overall for this bearing outer ring, figure 2 pieces of bearing inner ring and shaft sleeve for this appearance, figure 3 of this bearing roller surface figure, figure 4 for the bearing cage. Figure 1 outer appearance appearance figure 2 pieces of inner ring and shaft sleeve appearance appearance figure 3 roller surface figure 4 cage appearance morphology from outer end face a crack extends to the surface of raceway ( FIG. 5) ; Outer ring rolling road running trajectory deviation occurs, a side grinding crack near one end chamfering, on the other side grinding crack about 30 mm, is apart from the other side the end surface of the raceway surface of burn, as shown in figure 6. Figure 5 outer ring crack morphology figure 6 outer ring raceway surface grinding crack morphology four pieces of inner ring surface damage characteristics of basic same, take one of the test piece. A crack across the next race ( Up and down direction based on the pictures is divided into the upper raceway and the rolling way) Surface to guard among, the raceway surface of the rolling deformation traces to guard; The raceway surface black, have burn phenomenon and spalling pit, and about 58 mm spacing, different length of about 17 mm wide extrusion deformation traces, as shown in figure 7. Figure 7 inner ring raceway surface damage morphology four roller surface corrosion is serious, also remaining roller surface rust; Traces are squeezing roller working surface deformation ( Figure 3) 。 Keep the surface corrosion is serious, one has broken ( Figure 4) 。 2, spherical roller bearing crack causes through the analysis of macroscopic and microscopic, and inner ring raceway surface rolling deformation traces to guard; Bearing working surface burns; Both ring surface cracks, at the same time both inner ring and roller surface plastic deformation, especially on plastic deformation of the area have a lot of tiny crack. The above phenomenon shows that the bearing is attributed to working surface burns and metamorphism, resulting in crack and fracture failure occurs, which can determine the bearing failure mode for cracking. Mechanical equipment used in heavy, large impact load, such as more dust under bad working conditions. Bearing deflect when the job is running, resulting in insufficient internal clearance, internal rolling body for movement space is limited, bearing the automatic tuning of cardiac function is affected, cause uneven bearing force, side roller and raceway produced extrusion, cause local excessive load bearing. Extrusion friction between roller and raceway to produce large amounts of friction heat, lubricating oil cannot carry more heat, the temperature rise of roller and inner and outer ring. Bearing temperature rise, in turn, has formed the oil membrane, there will be a roller and the ring of the dry friction, the heat generated by the more and more, great heat, generated by the inner and outer ring and roller temperature rise sharply, especially the inner ring raceway near surface layer temperature in a short period of time than the austenitizing temperature, make the inner ring raceway surface layer near the secondary hardening. Bearing operating temperatures make the material in the process of organization and intensity change, when stress ( Including thermal stress because of the secondary hardening) Exceeds the tensile strength of the material, the material will appear crack. In the subsequent operation, crack extension, until the break. 3, spherical roller bearing carbide network defect analysis of the existence of the carbide network can weaken the relationship between metal matrix grain, reduce the mechanical properties of bearing steel, especially the impact resistance performance, and with the increase of carbide network severity, impact toughness and contact fatigue strength is reduced. The bearing inner ring it is part of the carbide network has closed, to a certain extent, reduce the inner ring of the shock resistance and contact fatigue strength. To sum up, bearing deflection occurred during operation, result in uneven produce extrusion friction and generate a lot of friction heat, heat the inner and outer ring and roller temperature, make the material physical properties change and crack, this is bearing the main reason for the failure occurred in the process of operation; In addition, the inner ring carbide network is unqualified, to a certain extent, reduce the mechanical properties of the inner ring, is the underlying factors leading to the invalid inner ring. To avoid the generation of this phenomenon, when installation, bearing should be installed, make it in the correct position and adjust the radial clearance, avoid the clearance is too large; In addition, also note that in the process of bearing operation should make lubrication is always in good condition, etc.