Performance of Koyo bearing material after heat treatment

• When brushing, it is not only necessary to avoid accumulation, but also to prevent coating leakage. It is generally applicable to some special shaped products or outdoor construction equipment that are not suitable for soaking or spraying.Performance of Koyo bearing material after heat treatment

Immersion method Koyo bearing material 

• The thickness of oil film can be achieved by controlling the temperature or viscosity of antirust grease. Some small items are soaked in antirust grease to make the surface adhere with a layer of antirust grease.
• The lubricating grease adsorbs the acid components volatilized from the paint, causing the deterioration of the lubricating grease, and this acid component promotes the hydrolysis of the grease. As a result, the concentration of the acid component increases, causing the corrosion of Timken bearing.
• The working principle of grease is to separate the steel ball from the inner and outer raceways by using the grease layer, adhere to the surface of the steel ball and raceway by using the viscosity characteristics of grease, separate the metal interface between the steel ball and the inner and outer raceways, reduce the wear of the metal surface, protect the metal from air and moisture corrosion, reduce vibration and noise, and enable Timken bearing to rotate smoothly.Performance of Koyo bearing material after heat treatment
• However, after the grease deteriorates, the viscosity will change, the oil film will break through, and the separation function and adhesion characteristics of the grease will disappear, resulting in serious consequences
• First, the acid components produced by insulating paint directly oxidize the metal surface, causing Timken bearing corrosion.Performance of Koyo bearing material after heat treatment
• Second, it causes the steel ball to directly touch the inner and outer raceways and wear during rotation, resulting in increased noise.Performance of Koyo bearing material after heat treatment
• As the main components of the locomotive, especially traction motor and axle box bearing, its function plays an important role in transportation. When the locomotive is running on the line, once the bearing fails, the whole train will not run, blocking the main line of transportation, especially the passenger train, which will have a greater negative impact. Performance of Koyo bearing material after heat treatment
• At the same time, once the locomotive bearing fails, it is also very difficult to rush repair the locomotive, Therefore, it is very important to prevent and reduce the occurrence of locomotive bearing faults for locomotive transportation. Whether the bearings with potential faults can be detected before Koyo bearing loading and ensure that qualified Koyo bearing accessories are put on the train is the focus of this paper.Performance of Koyo bearing material after heat treatment
• Failure of Koyo bearing
• The serious damage of Koyo bearing is often not caused by a single cause, but by the combined action of several aspects, a vicious cycle occurs under bad operating conditions, resulting in the serious burning loss of the bearing. Therefore, after the accident, it is often difficult to judge the cause, which brings us some difficulties in formulating relevant measures. For the convenience of discussion, first analyze the causes of the failure of Koyo bearing from several aspects.Performance of Koyo bearing material after heat treatment

Effect of installation on Koyo bearing

• When assembling the bearing, the copper hammer is not used to impact the bearing according to the process requirements, resulting in the deformation of the cage, the incorrect installation of the inner and outer rings of the Koyo bearing of the traction motor, or the disappearance of the axial transverse momentum due to other reasons, resulting in the extrusion of the bearing shaft.
• Improper assembly and fit clearance of Koyo bearing can also easily lead to bearing failure. Small clearance can easily lead to friction and heating of rollers and raceways. With the continuous rise of temperature, the temperatures of inner ring, body, cage, outer ring and end cover of Koyo bearing are different, and there is a temperature difference between them. Performance of Koyo bearing material after heat treatment
• Therefore, the expansion amount is also slightly different, which will further reduce the fit clearance and increase the heat generation of Koyo bearing. If the clearance is too large, the vibration of the roller will increase, which will aggravate the impact of the roller and the raceway. At the same time, it is easy to cause uneven internal load distribution, reduce the bearing roller and overload the central roller.Performance of Koyo bearing material after heat treatment
• The interference of the fit clearance between the inner ring of Koyo bearing and the shaft is inconsistent, which is also easy to cause bearing failure. Large interference is easy to cause the inner ring of Koyo bearing to crack due to excessive tensile stress, and too small interference is also easy to cause “Relaxation” of the inner ring of Koyo bearing.

Abnormal wear of Koyo bearing

• When the Koyo bearing is used for a period of time, certain defects and scars will appear on the inner ring, body, cage, outer ring and raceway of the bearing, resulting in poor bearing lubrication and bearing heating. Long-term heating will lead to:  
• dilution of Koyo bearing lubricating oil. Therefore, when running on the line, if it is found that the bearing is seriously hot and smoking, do not stop, but keep running to the front station, because at this moment, the overheated Koyo bearing is in the melting state. Performance of Koyo bearing material after heat treatment
• Once it is stopped and cooled, it can no longer walk and block the main line. Due to the above reasons, a vicious circle is further formed, which accelerates overheating and burns the bearing.  Accelerate the fatigue of materials and reduce the hardness. Serious bearing inner ring displacement, body out of round, collision and heat generation, and finally welded together.Performance of Koyo bearing material after heat treatment
• Oil supply and maintenance of locomotive bearings is very important. In particular, proper oil filling of bearings can ensure good lubrication of Koyo bearings. Lack of oil and excessive oil filling are also easy to cause bearing failure. Adding less oil is easy to cause poor lubrication and heating of Koyo bearings, and adding more oil is also easy to cause overheating of mixing. Therefore, proper oil supply in maintenance and cleaning of bearing lubricating grease are also very important, Once other impurities and moisture fall into the grease, it will affect the normal clearance and establish the necessary oil film.
• The service time of Koyo bearing is too long, which exceeds the service life of Koyo bearing and is easy to cause material fatigue. In addition, the material is deformed due to strong impact, resulting in peeling and grinding of rollers and raceway surfaces, resulting in poor lubrication and increased vibration. Contact fatigue failure is the main form of normal failure of Koyo bearing.Performance of Koyo bearing material after heat treatment
•  When the rolling bearing is running, the rolling element rolls between the raceways of the inner and outer rings of the bearing, and its contact part bears periodic alternating load, which can reach hundreds of thousands of times per minute. Under the repeated action of periodic alternating stress, fatigue spalling occurs on the contact surface. After the rolling bearing begins to peel off.Performance of Koyo bearing material after heat treatment
• it will cause the vibration and noise of Koyo bearing to increase, and the working temperature will rise sharply, resulting in the final damage of Koyo bearing. This damage form is called contact fatigue damage. Therefore, Koyo bearings require that the steel used for rolling bearings should have high contact fatigue strength.Performance of Koyo bearing material after heat treatment
• When the rolling bearing works normally, it is accompanied by sliding friction in addition to rolling friction. The main parts of sliding friction are: the contact surface between the rolling element and the raceway, the contact surface between the rolling element and the pocket hole of the cage, between the cage and the retaining edge of the ferrule, and between the end face of the roller and the retaining edge of the ferrule. Performance of Koyo bearing material after heat treatment
• The existence of sliding friction in Koyo bearing rolling bearing inevitably causes the wear of Koyo bearing parts. If the wear resistance of bearing steel is poor, the rolling bearing will lose its accuracy prematurely due to wear or increase the vibration and reduce the service life of Koyo bearing due to the decline of rotation accuracy. Therefore, Koyo bearing steel is required to have high wear resistance.Performance of Koyo bearing material after heat treatment
• The basic requirements for materials of rolling bearings largely depend on the working performance of Koyo bearings. The selection of suitable materials for manufacturing rolling bearings will have a great impact on its service performance and service life. Generally, the main failure form of rolling bearing is fatigue spalling under alternating stress, bearing and loss of bearing accuracy due to friction and wear. Performance of Koyo bearing material after heat treatment
• In addition, there are cracks, indentation, corrosion and other reasons that cause abnormal damage to Koyo bearings. Therefore, rolling bearings should have high plastic deformation resistance, less friction and wear, good rotation accuracy, good dimensional accuracy and stability, and long contact fatigue life.Performance of Koyo bearing material after heat treatment