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The relationship between industrial robot accuracy and bearing design
Jan 17, 2019

For industrial robots, accuracy is a very important factor that directly affects product quality and productivity. The main factor affecting the accuracy of industrial robots is the bearings. So what kind of bearings can make industrial robots have higher precision? 

1. Design of key structural parameters

Industrial robot bearings have the requirements of long life, high rigidity and low friction. Therefore, when designing industrial robots, not only the maximum rated dynamic load should be considered, but also the optimal value of each structural parameter should be carefully selected to improve the contact stress distribution of the bearing parts. Then it can reach the optimum contact state for the formation of the lubricating oil film and improve the service life of the bearing.

2. The raceway position

The inner and outer rings of the contact ball bearing of the industrial robot adopt the integral structure, and the general sectional area is only 20% of the bearing with the same inner diameter standard, so the radial wall thickness of the cage is very limited. If the position is designed in the middle of bearing width, the bearing becomes a symmetrical structure and the strength of the bottom of the cage and the mounting position of the sealing ring will be limited. Therefore, in order to ensure that the bearing cage has sufficient strength and the sealing ring has sufficient installation space, the groove position adopts an asymmetrical design on both end faces.

3.The height of the flange

When the contact ball bearing of an industrial robot is in working condition, it must bear a certain axial load while receiving a certain radial load. If the axial load is too large, it may cause the break of contact ellipse between the steel ball and the edge of the inner and outer rings or between the flange and the raceway. And then, stress concentration will occur and the bearing ring will be worn, which will affect accuracy.

Therefore, when the flange height is designed, the minimum flange height J of the bearing ring is calculated according to the Hertz contact stress theory according to the axial load of the bearing, and the diameter of the ring flange is calculated. In the design, the contact ball bearing cross-sectional area is considered small, and the flange height coefficient can be smaller than the deep groove ball bearing under the premise of satisfying the use requirement.

4. Sealing structure design

If the sealing property is not good, the impurities or other contaminants in the air will easily enter the bearing, thereby gradually failing the grease and resulting in bearing damage. Therefore, the sealing of the bearing is critical. When designing sealed bearing, it is necessary to consider the sealing and the specific working requirements of the bearing and the specific structural form of the bearing.

Industrial robots are moving toward miniaturization, light weight, and precision. Therefore, the lubrication of bearings for industrial robots is preferably greased by means of a lubrication method with a sealing structure.

5.The characteristics of industrial robot bearing

There are two ways to match the inner ring of the bearing and the sealing lip:

Contact seal with inner ring seal lip in contact with inner ring rib

Non-contact seal with inner ring seal lip in contact with inner ring rib

ZYS can offer the complete solution for industrial robot bearing. Any demand, please send email to zysdong@gmail.com.