how to repair the motor core?
The stator and rotor core of the motor are laminated by silicon steel sheets. The silicon steel sheets are insulated from each other and pressed by an iron ring or fixed on the casing or the shaft by a ring key.
Common faults of the iron core include surface scratches, insulation damage between sheets, loose core, silicon steel sheet fan and slotted fuses.
The surface of the iron core is mostly caused by bearing damage, bending of the shaft, wear of the end cover, poor assembly quality or falling into foreign objects. When the surface of the iron core is scratched, it can be corroded with nitric acid, and it is not necessary to take out the coil, which has no effect on the insulation of the silicon steel sheet.
Before the corrosion with nitric acid, the nitrate solution with a concentration of 34% is prepared; the ventilation groove between the core segments is blocked with asbestos cloth or glass cloth; the gap between the surface of the coil and the wedge near the scratch and the core is The oil ash is tightly sealed to prevent the nitric acid solution from flowing into the inside of the coil; the iron core to be corroded is exposed, and the rest is covered with asbestos.
After that, the silicon steel sheet in the short-circuited area is polished by the hand grinding wheel along the direction of the core grain until the line between the sheets can be seen to prevent the short-circuit depth from expanding. Brush the cleaned short circuit with a brush and nitric acid solution until the silicon steel sheet is short-circuited and burred, showing a clear pattern between the sheets. Then clean the surface of the corroded iron core with a brush and water, and then apply the test paper soaked with alcohol to the surface. If the test paper is not red, it means no acidic reaction. Finally, according to the insulation grade of the silicon steel sheet, the corresponding insulating varnish is applied to the surface of the treated iron core and dried.
When the iron core is loose or the pressure ring on both sides is not tight, two steel plates can be used to make a disc with an outer diameter slightly smaller than the inner diameter of the end of the stator winding, and a stud bolt is inserted through the center opening, and then the stud bolt will be tightened. Core clamping.
When the groove is skewed, it can be corrected with a needle nose pliers. If the core is slack in the middle, a hard insulating material such as insulating cardboard can be inserted into the slack. If there is burr or mechanical damage on the silicon steel sheet, the burr can be removed by fine boring, the dent is flattened, cleaned with gasoline, and then coated with a layer of insulating varnish.
When the surface of the iron core is burnt out or melted and does not extend to the depth of the core, the burned or melted part can be removed with a chisel, and the burr is removed with a fine squeegee and scraper to remove the foreign matter. Layer insulation paint.
Fan Zhang is a common phenomenon of iron core, and it is a hidden danger that cannot be ignored. Although it can not cause an accident immediately, it is very harmful. Under the action of electromagnetic force, the toothed piece of the fan will generate vibration to increase the noise of the motor; the punching of the fan will cause grounding failure of the coil due to continuous wear of the coil insulation; the punch of the fan will be vibrated due to long-term vibration. It will be fatigued and broken, and the broken piece will easily scratch the insulation of the end coil.
The reasons for the iron core fan are: when the old coil is removed, the tooth punching piece is overwhelmed by the operation, causing the punching piece to bend and deform; when the old coil insulation is burned by heating, the end of the tooth is overheated and deformed. The insulation is burnt, the punching piece is warped outwards; the end pressing device is not perfect or there is no pressing device at all.
When the iron core is flanked, the first is to increase the auxiliary pressure ring to press the fan part of the punching piece; in addition, the rust and oil on the fan sheet can be cleaned with gasoline, and the iron core is heated to 50-60 ° C. The prepared epoxy resin glue is filled into the slit of the fan sheet, and then the fan sheet is pressed to the normal position by the clamp, and is cured at room temperature for 8 to 12 hours under pressure, and the compacting jig can be removed.
In small motor operation, the fan value of the core tooth cannot exceed the value specified in Table 1.11.
When the iron core is short-circuited, the coil is short-circuited, or the coil is ground-to-ground, the arc is broken, and the iron core and the groove are partially burnt.
When the iron core groove is partially burned, the coil in the burned area is taken out, and then the bonded block sintered on the silicon steel sheet is cleaned by a flat chisel or a steel shovel, and the iron core is unevenly wounded by a small diameter wind wheel. Polished flat. Use a blade to pry the teeth into pieces and remove the burrs and apply the silicon steel sheet insulation paint. If the punching sheet is difficult to open, it can be treated with a nitric acid solution and then coated with an insulating varnish.
The part of the core that is squeezed during the inspection process shall be coated with 462 asphalt paint for protection.
