3 squirrel cage rotor failure repair
The repair of the squirrel-cage rotor failure is difficult, and the repair methods are as follows.
(1) Replace the rotor
Directly replace the new rotor of the same specification.
(2) Partial repair welding
If there are few broken bars, the fracture is on the outer surface and repair welding is possible. Use a sharp chisel to remove the groove or trapezoidal groove on both sides of the crack of the cage or end ring, and heat the rotor to 450 °C with a torch or oxygen: fast flame, then tin (630%), zinc (33%) and aluminum. (4%) consisting of solder repair welding. After the repair is completed, the excess solder car will be removed or shoveled.
(3) Cold connection method
Drill the well at the split with a drill bit similar to the slot width of the rotor core slot, then screw an aluminum screw and remove the excess of the screw with a lathe or blade. If the squirrel cage is severely broken, the crack or crack is long, and only one screw can not be connected. You can use a sharp chisel to cut a rectangular groove at the crack, and then use a shape and volume similar to the rectangular groove. The size is slightly larger. The aluminum block is forcibly pressed into the rectangular groove, and the hole is drilled at the joint of the aluminum block at the two ends of the aluminum block, and the aluminum screw is screwed and the excess portion is removed.
(4) Strip method
If the motor is broken and the new rotor cannot be replaced, the original aluminum cage can be melted and replaced with a copper cage. The method of melting the aluminum squirrel cage is to use the original end ring with a lathe, clamp the rotor core with a clamp, and immerse it in an industrial caustic soda solution with a concentration of 600/0, after 6-7 hours (if the caustic soda solution is heated) To 80-100't, the corrosion rate is faster. Immediately after the corrosion of the aluminum strip, rinse with water, then put it into 0.25% glacial acetic acid solution and boil for about 15 minutes to neutralize the caustic soda remaining on the iron core, then put it into the water to boil. Take out and dry after 1-2h. After the aluminum is melted, a copper strip having a cross-sectional area equal to about 70% of the rotor slot area is inserted into the groove, and the copper strip must be pressed against the notch and the bottom of the groove, so that there is no room for movement; the two ends of the copper strip protrude from the notch 20- 30mm, then the end ring of the car is drilled according to the position of the rotor slot, and it is placed on the copper strip. The copper strip and the end ring are welded by silver or phosphor bronze.
