Raising problems and the improvement of the design of front mounted roller notch process and the process design of rear bearing roller notch.

Taking the inner ring of 232/900cak30/c3w33 bearing as an example, this paper improves the design of the existing roller gap, and solves the problem that the assembly sleeve of extra large spherical roller bearing damages the raceway.

1. Raising problems

In the process of assembling the oversize spherical roller bearing, there are always gouges on the raceway at the notch, which seriously affects the service life of the bearing. Check the size of each processing part and it fully meets the processing requirements of the drawing. However, there are still gouges on the raceway at the notch of the roller. It is necessary to solve the problem of gouges on the raceway from the design of the notch.

2. Improve the design of front mounted roller notch process

Before the improvement, the notch direction of the inner ring mounted roller of the extra-large spherical roller bearing is designed to be parallel to the axis direction of the inner ring. There is a notch on each side of the retaining edge. The gap between the two retaining edges is 180 ° apart. The depth from the notch to the bottom of the raceway is about 10 ~ 12mm. When assembling the sleeve, the cage is placed on the outer surface of the inner ring. Because there is no roller installed, the inner raceway and cage have a large space. The cage can lean against the side of the ferrule. It is easy to install the rollers. When the number of rollers is half, the rollers occupy a large space in the inner raceway and cage pocket. It is difficult to install the rollers into the pocket. Only use a copper hammer to hit the rollers into the cage pocket along the notch, Cause serious damage to the raceway at the gap of the mounting roller. It can be concluded that the design of notch depth is unreasonable. In order to reduce the damage of the raceway, we have used the method of padding the raceway with copper sheet at the notch for assembly, but the effect is still unsatisfactory. When such a bearing is used by users, early rolling fatigue will be formed at the bruise of the raceway, resulting in fish scale peeling, which will seriously affect the service life of the bearing. On the other hand, the notch design has a notch on each side of the retaining edge, and the gaps between the two retaining edges are 180 ° apart. This depends on the number of rollers in each row, because the cages of Ca type spherical roller bearings are solid frames, and the two rows of pocket holes of the cages are staggered. When the number of rollers in each row of the bearing is an odd number, the gaps between the two rows are 180 ° apart. During assembly, rotating the inner ring once can install a roller from the gaps on both sides, When the number of rollers in each row of the bearing is even, the gap between the two rows is 180 °, which cannot ensure that the rotating inner ring can be installed into one roller from the two gaps at a time during assembly. Only after half of the rollers are rotated can the rollers be installed into the other gap, which increases the labor intensity of the assembler and reduces the fitting efficiency. Figure 1 shows the gap design dimension of the roller installed before the improvement of 232/900CAK30/C3W33 bearing inner ring.

Figure 1

3. Improve the process design of rear bearing roller notch

From the above analysis, it can be seen that the depth design of bearing inner race notch is unreasonable. The axial and radial chamfer of the bearing roller are 3mm. The depth of the notch is greater than the chamfer coordinate, so there will be no roller falling from the notch. Therefore, the depth of the notch needs to be deepened. After improvement, the depth from the notch to the bottom of the raceway is 5mm. After verification for many times, the depth is reasonable, and there is no roller falling. There is a certain angular relationship between the cage pocket and its axis. Whether a small slope with a similar angle to the cage pocket can be designed on the notch path that the roller must pass through, which has a buffering and pushing effect on the installation of the roller into the raceway. This can not only reduce the pressure on the roller by the edge of the cage pocket claw, but also reduce the knock caused by the impact of the roller on the raceway surface. It is this idea that the roller gap in the inner ring of super large spherical roller bearing is designed to form an angle of 4 º ~ 6 º with the axis direction of the inner ring. There is one notch on each side of the flange. The distance between the two notches depends on the number of rollers. When the number of rollers is odd, the distance between the two notches is 180 º. When the number of rollers is even, the distance between the two notches is 180 º minus the degree of half a roller. For example, the number of 232/900CAK30/C3W33 bearing rollers is 20 rollers in each row. The angle of each roller on the circumference is 18 º, and the degree of half a roller is 9 °, so the distance between the two notches is 171 º, In this way, the inner ring can be rotated once, and the rollers can be installed from the notches on both sides, which reduces the labor intensity of the assembler and improves the fitting efficiency, and is deeply welcomed by the assembler. The 4 º ~ 6 º angle between the notch and the inner ring axis is obtained through a large number of process tests according to the cage pocket angle, roller diameter, roller length and small edge width. Generally, the "232" series small edge width is wider, and the angle can be larger. The "241" series small edge width is narrower, and the angle can be smaller. The processed angular notch looks like a "pear". The notch near the end face is wide, and the notch near the raceway is narrow and has a 5 ° slope. In this way, the gradient of installing rollers from the notch will play an auxiliary role. The rollers can be installed with a small force, realizing a new breakthrough that the assembler can push the rollers into the raceway by hand, and the raceway surface is only slightly scratched, the service life of the bearing is improved. As shown in Figure 2, the notch design size of 232/900CAK30/C3W33 bearing inner race after improvement.

Figure 2

4. Use effect

After the inner ring raceway turning is finished, the notch shall be processed. On the T68 machine tool, the product shall be placed on the bending plate, the bending angle shall be adjusted by 5 °, and then the notch shall be processed with the ball mouth milling cutter. After the processing is completed, the depth of the notch shall be checked with the caliper, and the shape shall be checked with the shape template. The depth and shape can be qualified. The difference is that the bending angle is adjusted. The bending plate with straight notch is vertical to the spindle of the machine tool, and the angle does not need to be adjusted. It is convenient to adjust the angle without increasing any labor intensity. Through the optimization design of the depth and angle of the notch and the angle between the two notches, the knock problem of the raceway is well solved, the labor intensity of the assembler is reduced, and the fitting efficiency is improved. It can be seen that it is feasible to improve the process design of the rear mounted roller notch, which has been widely used.

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