KOYO cylindrical roller bearing is analysed the cause of the service life

Rough on the bearing parts can observe the microstructure after quenching overheat. But exactly judge the degree of superheat must observe the microstructure. If appear in GCr15 steel quenching organization coarse acicular martensite, organization for quenching overheating. Reasons may be the high quenching heating temperature or heat insulation time is too long cause comprehensive overheating; Also may be due to the original organization banded carbide, low carbon zone between two belts forming local martensite acicular bulky, cause local overheating. Overheating in the organization retained austenite increase, dimension stability. Overheating due to quenching organization, steel crystal bulky, to cause a decline in parts of toughness, impact resistant performance, lower KOYO bearing's life also. Serious overheating will cause the quenching crack quenching temperature on the low side or even bad cooling will generate more than standard stipulated in the microstructure of austenite organization, called owe hot organization, it decreased the hardness, wear resistance sharply reduced, affecting the service life of roller bearing bearing parts in the process of hardening cooling by internal stress formation of quenching cracks crack said. Of the cause of the crack are: due to quenching heating temperature is too high or cooling, the thermal stress and quality of metal volume change of the organization stress is greater than the fracture strength of steel; The original defects on the surface of the work ( Such as surface microcrack or scratches) Or steel internal defects ( The non-metallic inclusions such as slag, serious, white spots, shrinkage residual, etc. ) When quenching form stress concentration; Serious surface decarbonization and carbide segregation; Parts hardening after tempering lack or not timely temper; The previous process caused by salt stress, cold forging folding, deep turning tool and the oil groove sharp edges, etc. In conclusion, the causes of quenching crack could be one or more of the above factors, the existence of internal stress is the main reason for the formation of quenching cracks. Quenching crack deep and long, fracture surface is flat, the broken section without oxidation color. It is often in the cylindrical roller bearing ring of longitudinal straight crack or annular crack; On the bearing steel ball shape with s-shaped, T or ring. The characteristics of the quenching crack is crack on both sides without decarburization phenomenon, with obvious difference between crack forging cracks and materials. KOYO bearing parts in heat treatment, there is the thermal stress and organization stress, the internal stress can overlay or partially offset each other, is complex and changeable, because it can as the heating temperature, heating rate, cooling, cooling speed, parts of the change of the shape and size changes, so the heat treatment deformation is inevitable. Know and grasp its change law can make the deformation of cylindrical roller bearing parts, Such as ring elliptic, large size up, etc. ) In the scope of the controllable, be helpful for production. , of course, in the process of heat treatment, mechanical collision also can make parts deformation, but the deformation is can be used to improve operation to reduce or avoid. Internal factors mainly refers to the structure design, manufacturing process and material quality and so on three major factors in determining the quality of bearing. Imported bearing materials metallurgy quality was the main factor affecting the premature failure of the rolling bearing. As metallurgy technology, For example, the bearing steel vacuum degassing, etc. ) Progress, raw material quality is improved. Raw material quality factor in the bearing failure analysis share has declined obviously, but it is still one of the main influence factors of bearing failure. Select material adequacy is still bearing failure analysis factors must be considered. Cylindrical roller bearing manufacturing generally go through forging, heat treatment, cutting, grinding and assembly, and multi-channel processing operations. The rationality of the processing technology, advanced, stability will also affect the service life of bearing. Which affects the quality of finished products bearing heat treatment and grinding process, tend to have a more direct relationship with bearing failure. In recent years the study of metamorphic layer of bearings working surface show that the grinding process and is close to the surface quality of the bearing. KOYO bearing analysis, the main task of the service life is based on a lot of background material, analyze data and failure forms, find out the main factors of bearing failure, so that the improvement measures are put forward, prolonging bearing, avoid cylindrical roller bearing sudden early failure.