Several practical methods in motor repair (Two)

26/10/2019

5Repair of the motor after the "and the hood"

After the winding type motor and the headgear break through the short circuit, the wire end is usually burned for a period of time, and the length of the wire can be used for repair. The specific method is as follows:

Use 1-2 250W infrared bulbs to locally soften the rotor end to release the gun, remove the copper foam, and then bend the burnt (flat) copper wire head slightly (for soldering). The length wire can be silver soldered or soldered. Care should be taken to protect the windings during welding to avoid burnout (protected with wet asbestos cloth (rope)). Flatten the weld after welding. After straightening the copper wire, wrap a layer of glass ribbon, apply insulating varnish, and dry it with an infrared bulb. When the wire is placed in the original position, a thin film of green paper is placed underneath, and then the excess portion of the copper wire is cut off, and the sleeve is placed and soldered. Finally paint at the repair site and dry. The copper sleeve is applied to the hood and the original size is made. Before the production, the copper piece should be tinned.

The motor with the headgear has a large capacity, and it is difficult to disassemble and install. The above method is suitable for on-site repair.

6 removal of the old winding of the motor

Generally, the soft windings must be baked before the wires are removed. However, for larger capacity motors, it is more difficult to soften and disconnect the wires, so the old windings can be removed by the following methods:

Use a flat spatula to remove one end of the winding and the cut is flush with the notch. The other end of the winding is cut with a metal scissors, and then the enameled wire in the groove is punched out with a suitable copper rod to clean the groove. If the copper rods are suitable and the method of operation is correct, the wires in each slot can be punched out together. When using the flat shovel, be careful not to smash the stator core.

When the line is removed by the above method, the drying process before the removal can be omitted, the time is saved, the electric energy is saved, and the disassembly is relatively labor-saving. However, this method is suitable for motors with a capacity of 7.5 KW or less. Since the casing of a small motor or a micromotor is small, it is inconvenient to operate using a flat shovel.

7 new brush grinding

The DC motor or rotor is a revolving motor renewing brush. When the brush holder is perpendicular to the surface of the commutator, the method of grinding the brush is to lay a piece of sandpaper on the surface of the commutator and hold the same type of new electric motor. The brush reciprocates frictionally along the commutator, and the surface of the brush is quickly ground to the arc surface that matches the surface of the commutator. Use coarser sandpaper first, then fine sandpaper. When grinding, hold the brush to be positive, and move back and forth along the axis of the commutator, not skewed, and the reciprocating stroke should not be too long. Care should be taken to prevent brush powder from entering the armature and commutator grooves. After grinding, put the brush into the brush holder. After the starter motor runs for a few minutes, take out each brush and check that the contact surface generally accounts for more than 80% of the total area. Otherwise, it should be re-ground until it is qualified.

When the brush holder of the motor is not perpendicular to the surface of the commutator, the following method should be adopted: the sandpaper is laid on the plane, and the hand brush is used to grind a slope according to the inclination angle of the brush holder. Then put the brush into the brush holder and turn the motor rotor by hand, so that the light point will be polished on the inclined surface of the brush, and then the light spot will be polished with sandpaper (can also be scraped with a knife). After grinding, put the brush into the brush holder and turn the motor rotor by hand. The same will be polished out, and the area is larger than the first time. After doing this several times, the contact surface of the brush will become larger and larger and gradually form an arc. When polishing bright spots, do not polish too much each time, especially to the last time, be careful, just rub a little with fine sandpaper. If you rub more, the contact surface will become smaller. It has been proved by practice that the inclined brush is ground in this way, and the time is fast and the effect is good.

8 emergency repair of rotor journal and end cap bearing chamber wear

The specific methods and steps are as follows:

1. Wash the area with ethanol or gasoline repeatedly.

2. The ternary nylon ethanol solution is heated to a transparent liquid, and the liquid is thinly applied to the worn portion with a small brush. For a slightly larger amount of wear, the heating time may be appropriately extended to make the solution thicker and then coated. Generally, it needs to be applied several times to reach the required thickness. After the first application, it should be placed for about 3 minutes, and it can be dried by itself. When it is not sticky, it can be applied for the second time.

3, dry after coating, can be heated (temperature does not exceed 80 ° C, time 0.5-1 hours), it can also let it dry naturally (at room temperature 20 ° C, placed in a ventilated place for about 36 hours).
 
4, the wear amount is less than 0.10mm, after drying, can be used. If the wear amount is greater than 0.10mm, in order to ensure the concentricity of the stator and the rotor during the assembly of the motor, it is necessary to perform turning after coating. During turning (if the original bearing outer ring and inner ring size are within the tolerance range), the repaired end cap bearing chamber can be processed according to P6. If the journal is repaired, it can be processed according to r6.

After the coated nylon solution is completely dried, it has sufficient adhesion and hardness, which can fully guarantee the requirements of the motor assembly.

This method is only suitable for cases where the amount of wear is not large, only a few tenths of a millimeter.