1. What tests should be done on the motor before repairing the mechanical fault?
In order to ascertain the cause of the fault and the approximate fault range, the following checks should be made on the outside of the motor before the mechanical fault of the motor is repaired:
Motor machine external inspection
1. Check the machine base and end cover for cracks, and whether the shaft has cracks or bending deformation.
2. Check if the rotor rotation is flexible, stable, whether the axis is swimming, and whether there is abnormal sound.
3. Check if the bearing is loose or stuck.
4. Check the air duct for blockage, whether the fan blades and heat sinks are intact.
5. For motors with large capacity, the air gap is generally measured on the end cover. The average value of the air gap non-uniformity can be detected within 15% by measuring the air gap.
6. Power-on operation, check whether the motor is normal by hand, ear, nose and eye. If an abnormality is found, the power should be cut off immediately to prevent the fault from expanding.
7. After the inspection determines the nature of the fault and clarifies the scope of inspection, the motor can be dismantled for further detailed inspection and repair.
For the mechanical part of the motor, the following checks should be made:
1. Check the surface of the rotor core for any scratches.
2. When there is only one scratch on the surface of the rotor, and the surface of the stator is completely scratched, it is caused by the bending of the shaft or the imbalance of the rotor; when there is only one scratch on the surface of the stator, and the surface of the rotor is scratched every week, then It is caused by the difference between the stator and the rotor, such as the deformation of the seat and the end cover, or the bearing wear is serious, causing the rotor to sink. If the surface of the rotor and the rotor have a large area of scratches, it is caused by the above two reasons. of.
3. Check whether the rotor core is aligned or not.
4. If it is not aligned, it is equivalent to shortening the core, and the magnetic flux density increases and the iron core is overheated. The reason is that the rotor core is axially clamped or the new rotor is replaced. In addition, it should be checked whether the rotor core moves in the circumferential direction. If there is a movement phenomenon, the screw that loosens the stator is loose or damaged, or the rotor core does not fit tightly with the shaft.
5. Check the rotor end ring for cracks or breaks, whether the blades are damaged or deformed, and whether the shaft is bent or not.
6. Check whether the inner casing of the bearing and the journal and the bearing chamber meet the requirements. Is there any over-tightening or looseness? Check the bearing wear level, whether the bearing is intact and whether the lubricating oil (fat) is too little or dry.
Second, how to disassemble the motor?
It is often necessary to disassemble the motor when servicing the motor. If it is improperly removed, it will damage the motor. Therefore, motor maintenance personnel must master the technology to properly disassemble and assemble the motor.
The following steps should be taken when disassembling the motor:
1. Remove all external wiring and mark each line end, especially the polarity end (DC motor).
2. Remove the pulley or coupling and record the distance between the coupling and the shaft.
3. Remove the commutator side end cap and bearing cap screws and open the end cap.
4. Open the ventilation window of the side cover of the commutator, take out the brush from the brush holder, remove the connection to the brush bar and mark it.
5. Before removing the commutator side end cover, mark the joint between the end cover and the base, then pad the wooden board, and evenly tap the edge of the end cover with a hammer to make the end cover stop slowly out of the base. And bearing outer ring. Mark the brush holder position and remove the brush holder.
6. Wrap the commutator with thick paper or cloth to keep the commutator clean and avoid bumps.
7. Remove the end cap screws on the extension side of the shaft and pull the armature together with the end cap from the stator core. Be careful not to damage the armature winding during operation.
8. To replace the bearing, the bearing screw on the shaft extension side can be removed, and the bearing outer cover, end cover and bearing can be removed.
9. All parts removed should be placed and stored in the order of disassembly to avoid loss and facilitate assembly.
10. When assembling the motor, the operation steps are the opposite of those when disassembling, just reset the parts and wiring according to the mark.