Design Improvement of Crown Type Solid Cage for Deep Groove Ball Bearing

Guo Xiaonan¹，Li Junhua²

( 1.Wafangdian Metallurgical Bearing Group Corporation，Dalian 116300，China; 2． Wafangdian Bearing Group Corporation，Dalian 116300，China)

Abstract: Aiming at the disadvantage of locking balls unstably for solid cage of traditional deep groove ball bearing，a radial boring crown type solid cage without rivets is designed，which is able to lock the balls excellently with the crown type elasticity，optimizing the process and increasing the material utilization，and enhancing the cage intensity and working life． It is proved that the new design can meet customer applications．

Key words: deep groove ball bearing; crown type solid cage; boring; manually squeezing

1. Traditional crown-shaped solid cage

The traditional solid cage of deep groove ball bearings with rivet structure is shown in Figure 1. The structural cage is bored radially from its outer diameter (along the A direction), and a ferrule rib or steel ball is used to guide the cage. Due to the closed structure, it is difficult to lubricate the guide surface especially when grease lubrication is used, so wear and burning damage often occur, which is more serious when the guide is inside.

For super and extra light series bearings, another type of cage is an open-end, rivet-free structure, as shown in Figure 2. The structural cage is axially bored from its end face. During assembly, in order to prevent the cage from falling off, a locking ball (direction A) is chiseled on its end surface. However, due to different operating levels, the ball lock may not be firm and the chiseling process may be inconvenient, so it is necessary to improve its structure.

This structure also has radial (A-direction) boring holes on the outer diameter of the cage, but leaves an appropriate locking amount at B. It is shaped like a stamped crown cage, except that the wall thickness is larger. During assembly, place the bearing flat on the platform of the press, separate the steel balls at equal distances and place them under the cage, and use the press to press fit (Figure 4). Because the pocket can be elastically deformed, it is convenient for the assembly and axial locking of the steel ball; the radial bearing is restricted by the inner and outer channels, which ensures that the cage is not easy to fall off.

2. Features of new crown-shaped solid cage

(1) Compared with conventional solid cages, this structure eliminates the processing of rivet holes and the riveting of rivets during assembly. It does not require demagnetization, saving labor and materials. Since the cage has an open structure, it is easy to lubricate.

(2) Compared with the cage without rivets, this structure eliminates the process of notching the end face to lock the ball, which saves labor and makes the ball locking stronger.

(3) Compared with stamped crown cages, its pocket containment area is larger, and its strength and lifespan are higher.

At present, the new crown-shaped cage is only used for super and extra light series bearings. More than 20 varieties have been processed, and more than 500 sets of bearings have been assembled. The largest cages for 61888M and 61976M bearings can be processed. Under the premise of ensuring product quality, each cage can save brass 1. 6 kg, when processing large quantities, it significantly improves productivity and saves processing materials. It has been proven by users at home and abroad that bearings equipped with new cages can meet their usage requirements.

3.Conclusion

(1) Use a three-point contact fatigue testing machine to complete the complete fatigue life test of the same batch of ceramic balls under different contact stresses, and use the maximum likelihood estimation method to estimate the life. The results show that the greater the stress, the longer the life of the sample balls. The shorter.

(2) Using the tensile stress life model, first calculate the material constants of the Si3N4 ceramic ball, and then predict the rated life of the ceramic ball under the other two sets of stresses. Compared with the rated life measured in the test, the errors are 4. 6% and 3. 7%.

(3) The results predicted by the tensile stress life model are close to the results measured by the test, indicating that the rolling contact fatigue failure of Si3N4 ceramic balls originates from the maximum tensile stress. The same batch of Si3N4 ceramic balls only need to be subjected to a fatigue test under one stress. Once the material constants are obtained, the model can be applied to predict the rated life under other stresses, thereby greatly shortening the test time.