The Classification of Industrial Robot Bearings

The development of modern industrial robots tends to be lightweight. To install bearings in a limited space, they must be small and lightweight. But at the same time, the robot's high load, high slewing accuracy, high running stability, high positioning speed, high repeat positioning accuracy, long life and high reliability require the supporting robot bearings to have high load carrying capacity, high precision, stiffness, low friction torque, long life, high reliability. Lightweight and high performance are a contradiction. Today we mainly introduce 2 types of bearings:

 

 

1. Thin-wall crossed roller bearings

The internal structure of the thin-walled crossed bearing adopts the rollers arranged at 90° to cross each other vertically. A single bearing can simultaneously bear the combined effects of radial force, bidirectional axial force and overturning torque. Spacer is installed between the rollers, preventing the inclination of the rollers or the mutual grinding between the rollers, and effectively preventing the increase of the friction torque. In addition, the rollers are arranged in a vertical cross arrangement to avoid the locking of the rollers. At the same time, because the inner and outer rings of the metal bearing are divided, the gap can be adjusted, and even if pressure is applied, high rotation accuracy can be obtained. Crossed roller bearings are widely used in industrial robots and rod end joint bearings for waist rotation.

 

 

2. Special bearings for harmonic reducer

Harmonic reducer is a type of reducer that uses a wave generator to control the elastic deformation of a flexible wheel and uses the controllable elastic deformation of a flexible stainless steel ball bearings to transmit motion and power. Its characteristics are compact structure, high motion accuracy, large transmission ratio, and are mostly used for robot joints with small and medium torques.

 

Harmonic reducer bearings can be divided into two categories: CSF / CSG series harmonic reducer bearings with split outer ring and inner ring as a whole, and SHF / SHG series harmonic reducer spherical plain bearings with inner and outer ring as a whole. The rolling elements of the harmonic reducer bearings are cylindrical rollers, which are distributed in V-shaped raceways which are vertically arranged at 90 degrees to each other. The structural characteristics of the harmonic reducer bearing make a harmonic reducer knuckle bearing capable of bearing loads in all directions such as axial load, radial load and overturning torque, and has high rigidity, rotation accuracy and composite bearing capacity. Robot harmonic reducer bearings also belong to the crossed roller industrial bearing series, with high bearing accuracy, flexible operation, small clearance and small error, compact shape. The bearing has its own mounting holes, which is convenient for customers to install directly. This type of bearing accounts for about 35% of China's industrial robot bearing market. And it's growing fast.

 

CSF / CSG series special crossed roller bearings for harmonic reducers are slightly different in structure from ordinary cross roller bearings. The basic structure is similar. The outer ring is divided and the inner ring has a whole structure. Compared with standard crossed roller bearings, there are many mounting holes in the inner ring and outer ring, especially the inner ring. From the outside to the inside, there are generally three layers of mounting threaded holes of different sizes and numbers. This is the biggest difference from the basic cross roller bearing in appearance. The materials are all made of GCr15 bearing steel, the outer ring is heat-treated by the whole quenching process, and the inner ring adopts the raceway surface high-frequency hardening process, which is the biggest difference compared with the ordinary crossed roller bearing process. The smoothness and accuracy of the roller bearing's running friction torque have a direct impact on the tooth meshing force and running stability of the harmonic reducer, and directly affect the service life of the harmonic reducer. The quality of the roller bearing directly determines the use effect and life of the harmonic reducer.