The iron core is an important and key component of the hydraulic oil pump motor. When the iron core is loose, there will always be some punching sheets or the end plates that press the iron core like tuning forks that vibrate under the action of electromagnetic force, making such noises.
1. Why does the iron core become loose?
During the operation of the motor, the iron core punching sheets expand due to heat, and the iron core punching sheets become loose. After the iron core becomes loose, vibration will occur between the punching sheets, causing further wear of the punching sheet insulation layer, and the loose gap of the iron core punching sheets tends to stabilize. Obviously, the loose gap caused by thermal expansion alone is not enough to cause noise failure, but once it is superimposed with abnormal factors, the problem becomes complicated.
2. How to prevent the core from loosening?
From many years of experience in producing and testing motors, it can be found that there is almost no problem of loosening of the punching plate due to the later use of the motor, and most motors can be found during the production process.
There are usually two factors that cause harmful loosening of the core: one is that the punching plate has burrs or unevenness, and the occurrence of this problem must be avoided by controlling the weight of the core; the other is that the pressure is in an uncontrolled state, and it must be strictly operated according to the specifications under the premise of ensuring that the pressure equipment displays normally.
3. Repair methods
(1) To repair the loose punching sheets at both ends of the core, you can make a wedge out of iron plate and insert it into the gap between the tooth pressure plate and the core, press it tightly and then weld it firmly with electric welding. You can also use a neutral detergent to remove grease and rust, dry it and apply epoxy glue, and cure it at room temperature under pressure for 8-12 hours.
(2) To repair the loose middle part of the core, you should first remove the coil and take different measures according to the different motor structures.
① For small motors that are pressed out, the stator core should be pressed out first, the core buckle and the hook should be loosened, and then a bulge should be made according to the inner circle of the core, and the core should be inserted into the bulge. Correct the slot sample rod to align the iron sheets in the slot. Finally, press the core on the press, buckle the core buckle and hook under pressure, weld it firmly with electric welding, and then press the entire core into the base. If the core structure is tightened with bolts, the tightening bolts should be tightened symmetrically and evenly to tighten the core.
② For the iron core with internal pressure structure, different repair methods should be used according to the degree of looseness. If the iron core is slightly loose, use gasoline to remove rust and oil stains from the loose part, wipe it clean, then use a sharp blade to expand the punching sheet, insert the mica sheet, and finally apply epoxy resin glue to solidify.
③ The stator iron core rotates as a whole in the base. In severe cases, the coil lead will be pulled off, causing a short circuit. The repair method is to tighten the positioning screws on the base. If it has been disengaged, the positioning screw holes can be opened again on the base. If the iron core rotates severely and the positioning screws are ineffective, the iron core pressure ring or the outer circle of the iron core can be spot welded to the base with electric welding. Or press the stator iron core out, and then evenly apply epoxy glue on its outer surface, and solidify it at room temperature. At this time, the heat dissipation of the motor is also good.
