There are two kinds of coordination between asynchronous motor shaft and rotor core.
General purpose squirrel cage rotor motor, interference fit between shaft and rotor core. It is suitable for continuous loading without impact load and running load.
Transition coordination + bond connection
The winding rotor motor and lifting and metallurgical motor (crane motor), the shaft and rotor core are transitional fit + key linkage. It is suitable for large torque starting and periodic frequent start and positive reverse operation.
Influence of fan load on motor
The fan type load belongs to the continuous and stable operating condition of the load change at the running time, but the surge phenomenon in the fault condition will superimpose the impact load. The peak load may exceed the interference force between the shaft and the rotor core, which leads to the loosening and sliding of the coordination relationship, and then the interference relationship between the overaxis and the rotor core is destroyed and even occurred. The relative motion is transferred to the gap coordination.
With the increase of the wear rate between the two, the matching gap between the two is further increased and the relative motion speed is accelerated. The rotation speed of the rotating shaft is significantly lower than the normal speed of the 2 pole motor or the stall of the motor.
The cause of stall and remedial scheme for asynchronous motor
The cause of stall of asynchronous motor
The surge phenomenon under the condition of fan fault is only a typical example of asynchronous motor stall. In combination, the torque imbalance between the shaft and the rotor core is likely to lead to the imbalance of the torque due to two factors, which leads to the stall of the asynchronous motor.
1) match the alternating load or additional impact load.
2) the quality problems in the manufacturing process, resulting in the interference level between the shaft and the rotor core, which is inconsistent with the design requirements.
Fault motor remedy
Check the wear degree of the rotor core and shaft, and take different remedial measures according to the actual situation.
Slight wear and tear
(1) electroplating process. First the shaft is retreated, then the brush plating method is adopted.
(2) roll flowers. Use lathe or hand to knit the matching parts with the iron core on the shaft, then prepare the appropriate pressure plate. Press the frame and use the jack to push the core back. After being in place, use the welder to gently weld three points between the iron core end and the shaft.