The process design of grinding undercut of tapered roller bearing with flanged outer ring is carried out and verified.

Key words: tapered roller bearing; Flange; grinding undercut 

The matched single row tapered roller bearing unit produced for a host supporting enterprise has a flange on the outer ring of one product component. In order to improve the positioning performance and axial bearing capacity of the flange, the user requires that the grinding undercut at the connection between the outer diameter and the flange end face is a smooth arc with a radius of no more than 0.8 mm. In order to meet the requirements of users to the greatest extent, the process design is carried out and verified according to the processing capacity of existing equipment.

1. Process before improvement

The same curvature design method as the finished product is adopted for the machining process of the joint between the front outer diameter and the flange end face, as shown in Figure 1. This process is easy to realize turning, but when grinding, because there is no special compound grinding equipment, it is impossible to process the outer diameter and flange end face at one time, so the method of step-by-step processing can only be used to process the outer diameter and flange end face one by one. Step by step grinding seems simple, but in the actual operation process, due to the influence of equipment accuracy and operation skills, it is very easy to leave edges and burn, and it is impossible to ensure that the radius of the connection between the outer diameter and the flange end face is not greater than 0.8 mm. The finished product requirements of smooth arc transition can not be guaranteed. After grinding, the connection between the outer diameter and the flange end face must be repaired by turning, which is very difficult. What is more serious is that when the final magnetic particle flaw detection is carried out on the finished parts, it is found that 20% of the products have grinding cracks at the connection between the outer diameter and the flange, which has major quality hidden dangers.

Fig. 1 process method before improvement

2. Process improvement method

In view of the problems of products in the original process, the process method is modified and adjusted. The specific method is as follows: the shallow over pass groove design is adopted during machining, and the improved process method is shown in Figure 2. By evenly eliminating the grinding allowance, after grinding to the size of the finished product, the shallow over distance groove is completely eliminated, that is, there will be no oil groove visible to the naked eye at the connection between the outer diameter and the flange end face after processing to the finished product. According to the improved process method, after considering the external diameter of the workpiece, the dimensional dispersion of the flange height, heat treatment deformation, expansion and contraction and other factors, the radial and axial coordinates of the grinding undercut are determined, and the shallow grinding undercut with the groove bottom radius of 0.4-0.7 mm is adopted. At the same time, the grinding amount of the side with flange should be strictly controlled when grinding the end face of the sleeve ring on the double end grinder.

Fig. 2 improved process method

3. Conclusion

The process design method of changing the connection between the outer diameter and the flange end face from no overtravel groove to shallow overtravel groove greatly eliminates the original quality defects. The products processed according to the improved process do not leave any trace of overtravel groove, edge and burn. No grinding cracks of any form are found during the final magnetic particle flaw detection of finished parts, which fully meets the quality requirements of users. The improved process method reduces the cost, improves the quality level, and has good popularization value.

More about WSW Tapered Roller Bearing：

The raceways of the inner and outer rings are tapered sections and the rollers are tapered, so the tapered surface of the raceway and the roller axis (if projected) will intersect at a common point on the bearing spindle. This geometry keeps the motion of the cone coaxial, and there is no sliding between the raceway and the outer diameter of the roller.

This conical geometry produces a linear contact surface that allows greater loads to be carried than spherical (ball) bearings with point contact. The geometry means that the tangent speed of each roller surface is the same as the raceway along the whole length of the contact surface, and there will be no differential scrubbing.

The rollers are stabilized and restrained by the flange on the inner ring, and their big ends slide against the flange, which can prevent the rollers from popping out due to the "pumpkin seed effect" of their conical shape. The larger the half angle of these cones, the greater the axial force that the bearing can bear.

WSW tapered roller bearing adopts outer ring and inner ring assembly. The outer ring is composed of an outer ring, and the cone assembly is composed of an inner ring, a roller and a cage. This bearing structure can withstand combined loads and provide low friction during operation. Rigid bearing applications can be achieved by adjusting a single row tapered roller bearing to a second tapered roller bearing and applying preload.