The wear of the roller end face of the high-speed short cylindrical roller bearing is a typical case. In order to avoid the repeated occurrence of faults, Bearing Network shares the relevant end face wear examples, finds out the actual cause of wear, and makes corresponding improvement measures. 1. Example of wear of roller end face of high-speed cylindrical roller bearing When a certain type of bearing is working in the field, an alarm fault of metal chips exceeding the standard occurs, and the bearing fails. Its typical failure characteristics are as follows: the end face of the roller is worn, and the two ends of the outer diameter are discolored at high temperature, as shown in Figure 1, and severe high-temperature wear and deformation of the beam and side beam have occurred in the cage pocket, as shown in Figure 2. The raceway rib is worn and deformed, see Figure 3. The inner raceway has peeled off, and the largest peeling surface is a rectangle with a length of about 22mm, as shown in Figure 4. The high temperature secondary quenching phenomenon has occurred in the peeling area. Fig.1 Wear picture of roller end faceFig.2 Wear morphology of cage pocketFig.3, 4 Rolling deformation of outer raceway rib and appearance of inner raceway spalling From the above failure characteristics, the bearing rollers have suffered serious deviation , and caused the wear of the roller end face, the cage pocket, the outer raceway rib, and the fatigue spalling of the inner raceway and high temperature secondary quenching. In recent years, there have been many similar failures of this type of bearing, all of which have appeared serious wear of the outer ring rib, serious wear of the roller end face, and contact fatigue spalling of the inner and outer raceways. 2. Bearing performance requirements The modified bearing is a single-row radial short cylindrical roller bearing with double ribs on the outer ring and no ribs on the inner ring. During operation, the outer ring is stationary, the inner ring rotates, and the inner ring speed is 41586r/min. The radial load is 147n. From the perspective of working performance requirements, the bearing has high rotation speed and low load, and it is easy to produce light load slippage during the working process. 3. Analysis of the cause of bearing failure When the bearing is running at high speed, if there is any slight disturbance or change (such as carbon deposits in the lubricating oil caused by high temperature, etc.) Abnormal sliding wear occurs between the roller end face and the outer ring rib. The outer surface of the roller will also slip with the surface of the inner ring raceway, and the result of the roller swing will also cause slip or wear on the inner surface of the cage pocket in contact with it, and a series of slip and wear will accompany it. with an increase in temperature. Over time, wear and temperature rise will increase until the bearing fails. The main factors that cause the dynamic instability of the roller and the occurrence of side sway are: (a) The accuracy of the roller. It mainly includes the linearity of the straight line segment of the roller, the symmetry of the arc slope and the chamfer, the difference in diameter and length, the difference in parallelism and perpendicularity of the end face of the roller, surface roughness, etc.; (b) The linearity of the raceway of the ring ; (c) parallel difference of outer ring ribs; (d) cage pocket accuracy. It mainly includes the vertical difference between the beam and the side beam, the wall thickness difference between the bottom and the end face of the cage, etc.; (e) the gap between the roller end face and the outer ring rib; (f) foreign matter interference. If the accuracy of the roller is not good, it will directly affect the dynamic balance of the roller under high-speed rolling conditions, thereby destroying the running stability of the roller. In the early stage of the dynamic instability of the roller, if the accuracy of the outer ring rib parallelism, the linearity of the ferrule raceway, and the cage pockets are high enough, the dynamic instability of the roller will be restrained, so that the It remains in normal operation, otherwise, dynamic instability of the rollers will be exacerbated. When the rollers have sliding friction with the rib of the ferrule at a very high rotation speed, the frictional heat generated is also very high. At this time, if the clearance between the end face of the roller and the rib of the ferrule is too small, it is difficult to form a lubricating oil film. The cooling effect here will also be severely affected, eventually leading to high temperature wear on the roller end faces and ring rib. Therefore, the wear fault of the roller end face of a high-speed short cylindrical roller bearing is the result of the combined effect of the above factors. The straightness of the raceway and roller of the faulty bearing ring was detected with a profiler, and it was confirmed that the original straightness of each part met the requirements, and the influence of this factor could be excluded. Through the design review, it is found that this type of bearing has low requirements for the mutual length difference between the rollers, the surface of the arc slope is a ground surface, and the roughness and accuracy are low; the outer ring ribs also have low requirements for the parallel difference of the reference end face. Factors should be the main factors affecting the dynamic stability of the rollers of this type of bearing at high speed. 4. Improvement measures According to the analysis results of the failure causes, the following technical improvement measures are formulated: (1) The parallel difference between the outer ring rib and the reference end face is increased from 5m to 3m; (2) The mutual length difference of each group of rollers is increased from 8m Increase to 4m, and the diameter difference is increased from 0.7131 to 0.5m; (3) Increase the requirement for the wall thickness difference of the cage end face at the bottom of the cage pocket (not more than 0.05mm); (4) Increase the surface thickness of the arc slope on both sides of the roller. Finishing requirements. (5) Increase the requirements for measuring the gap between the roller end face and the outer ring rib. The improvement effectively improves and enhances the dynamic stability of the rollers during high-speed rotation, so that the quality of the bearings produced in the later stage is greatly improved, thereby improving the life and reliability of the bearings and ensuring the safety of the main engine. The improved bearing, installed and used,Similar failures have not occurred again, and the improvement effect is good.
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