Most motors use rolling bearings. The friction between the rolling element of the bearing and the inner and outer rings is rolling friction, and the friction between the two contact surfaces is very small.The fit between the bearing and the shaft, the bearing and the end cap is generally an interference fit, and in a few cases it is a transition fit.The mutual extrusion force of each other is relatively large, resulting in static friction. The bearing and the shaft, the bearing and the end cap remain relatively stationary, and the mechanical energy is transmitted by the rotation between the rolling element and the inner ring (or outer ring).

If the fit between the bearing, the shaft and the bearing chamber is a gap fit, the torque will destroy the relative stationary state and cause sliding. The so-called “running ring” occurs. The sliding of the bearing inner ring and the shaft is called the running inner ring, and the sliding of the bearing outer ring and the bearing chamber is called the running outer ring.

The appearance and hazards of bearing running laps

If the bearing ring is detached, the temperature of the bearing part will be high and the vibration will be large.Disassembly inspection will find slippage marks on the surface of the shaft (bearing chamber), and even grooves on the surface of the shaft or bearing chamber.From this situation, it can be concluded that the bearing is running laps.

The negative impact of the bearing running outer ring on the equipment is very large, which will intensify the wear and tear of the matching parts, and even scrap, and even affect the accuracy of the supporting equipment; in addition, because of the increased friction, a lot of energy will be converted into heat and noise, which greatly reduces the efficiency of the motor.

The cause of bearing running laps

(1) Matching tolerances: There are strict requirements for the matching tolerances of bearings and shafts (or bearing chambers). Different specifications, accuracy, force conditions, use conditions, etc. have different requirements for matching tolerances.

(2) Processing and installation accuracy: refers to the processing tolerance, surface roughness, assembly accuracy and other technical parameters of shafts, bearings, and bearing chambers.Once the requirements are not met, it will affect the matching tolerance and cause the bearing to run in circles.

(3) The material of the shaft and bearing is very critical.Different types of bearings should be made of suitable bearing steel. The strength and stiffness should be large, the wear resistance should be good, and the friction coefficient of the bearing alloy should be small, so as to ensure the normal use of the bearing and reduce the possibility of running laps.

Commonly used repair measures for bearing running rings

At present, the common methods for repairing bearing running rings in China are inlay, pitting, surfacing, brushing, thermal spraying, laser cladding, etc.

Surfacing: Surfacing is the welding process of applying a metal layer with wear-resistant, corrosion-resistant, heat-resistant and other properties on the surface or edge of the workpiece.

Thermal spraying: Thermal spraying is a metal surface processing method that atomizes the spraying material in the molten state and jets it on the surface of the part through a high-speed air flow to form a spray coating.

Brushing: Brushing is the process of obtaining a coating on the surface of the workpiece by electrolysis.

Laser cladding: Laser cladding, also known as laser coating or laser cladding, is a new surface modification technology.