Maintenance skills for the motor of the hottest el

2022-07-26
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Maintenance skills of electric excavator motor

the demand between the normal magnet and the operating self-supporting static load system is very small, but the constant air gap commutator should maintain a smooth cylindrical surface without scratches and burns. When the commutator operates under load for a long time, there is a layer of glaze or dark brown hard film on its working surface, which is conducive to the commutation of the motor and reduce the wear of the commutator. Generally, it is not allowed to wipe it off. If the outer circle of the commutator is elliptical and the surface is rough or has burning marks, the motor can be rotated for grinding (only 00 abrasive paper can be used for grinding). When the surface of the commutator is too uneven or there are serious burns that can not work normally, the commutator shall be turned. The cutting speed during turning shall not be greater than 5m/s, the feed rate shall not be greater than 0.2mm. There shall be no axial movement during turning, and the armature coil end and the commutator cover plate shall be covered to prevent copper chips from falling into the motor. If the mica sheet is found to be at the same height as the reversing sheet after turning, the mica sheet must be cut down with a knife saw or a small milling cutter 5mm and chamfered. After all processing is completed, use compressed air to blow away all the crumbs in the mica groove. If there is carbon dust or dust on the surface of the commutator, it can be wiped with a clean cloth. If there is oil stain, it can be wiped with a small amount of gasoline (gasoline must not be used when the motor is running)

2. Maintenance of brush

the brush must be in good contact with the commutator. The brush must be replaced when it is worn to the lowest height or damaged (the replaced brush must be consistent with the original brand). The newly replaced brush shall be ground with 0 or 00 sand paper (coarse sand paper or emery paper is not allowed), the width of the sand line shall be equal to the length of the commutator, the smooth side shall be close to the commutator surface, and the sand paper shall be pulled back and forth by hand until the contact surface of the brush is consistent with the commutator surface. When the abrasive paper is taken out from the surface of the commutator after grinding, the electric drama must be lifted first. After grinding, the debris on the brush holder and the commutator must be carefully removed, and then blown away with wind. Do not blow the debris into the motor

after the brush is replaced, it must be operated under light load (1//4 of the rated load) until the surface is smooth. After the commutator is turned or the brush holder is moved, the brush holder must be adjusted so that the distance between its edge and the commutator surface is mm, and the brush can slide freely in the brush box. During disassembly and assembly of the electric brush, the center position of the brush shall remain unchanged as calibrated by the original manufacturer

3. Bearing maintenance

3.1 bearing lubrication and cleaning

the maximum allowable temperature rise of the bearing is 55 ℃ (thermometer method). When the temperature is too high or there is uneven knocking sound, it indicates that the bearing may be damaged or have foreign matters, which should be inspected and cleaned immediately. If the bearing works normally, the oil shall be added at least once every 6 months, and the lubricating cell shall be replaced once a year. All DC motors are equipped with grease nipples on the bearing cover, which can be refueled without stopping. When refueling, align the oil gun with the oil nozzle and remove the waste oil in the bearing by using the pressure of new oil. If the bearing is found to be cracked, the steel ball (column) is cracked or excessively worn, and other damages are found, the bearing must be replaced immediately. If no defect is found in the bearing after inspection, and there is still excessive temperature rise or noise during use despite cleaning, the bearing also needs to be replaced. When disassembling and assembling the motor (the ball bearing is always left on the rotating shaft, and the outer ring and roller of the roller bearing are left on the end cover), the bearing must be properly protected from collision or dust and debris

3.2 steps to remove the bearing

(1) take out the armature from the stator, and then clean the bearing and bearing inner cover with gasoline. During cleaning, the armature shall be placed obliquely so that the cleaned shaft end is downward to prevent dirty oil from flowing into the armature

(2) remove the inner race of ball bearing or roller bearing

(3) take out the bearing outer housing and rollers from the end cover and clean them

(4) finally, wipe it with a cleaning cloth

3.3 assemble the bearing

(1) place the bearing in the oil groove and preheat it to ℃. All bearings shall be immersed in oil during heating, and new bearings shall be cleaned with gasoline first

(2) heat the inner ring and put it on the shaft until it is close to the shaft shoulder

(3) take out the bearing from the oil groove and immediately put it on the shaft until it is close to the inner tightening ring or shaft shoulder. The copper cushion block can be padded to knock gently during the sleeve to make the bearing enter evenly. If it is still difficult to fit after preheating, a hollow iron pipe with a diameter similar to that of the inner race of the bearing can be used. Therefore, the stripe spacing can be used as a measure of the local fatigue crack growth rate. One end of the iron pipe is against the inner race of the bearing, and the other end is gently knocked with a hammer to make the bearing enter evenly

(4) for the outer race of the liquid column bearing, gently tap the outer race with a copper cushion block to make the outer race enter the end edge evenly

4. Winding maintenance

during each motor inspection, the insulation resistance of the winding shall be measured. If it is lower than the specified value, the sample shall be dried in the fixture to avoid slipping or fracture before the test until the insulation resistance meets the requirements. The surface of the motor unit shall be protected from oil erosion, and the dust and dirt on the winding and connecting line shall be removed frequently. When the surface covering paint cracks or falls off, the insulating paint shall be recoated

5. Maintenance of long-term shutdown

(1) check the internal and external parts of the motor to eliminate the defects found

(2) blow out the inside of the motor after cleaning the clutch and commutator with cloth

(3) wrap the commutator with paper

(4) install the brush in the play box

(5) cover the outside of the motor with cloth to prevent dust and debris from falling into the motor

(6) apply antirust oil to the shaft extension

in a word, only by strengthening the daily maintenance of the excavator motor can we reduce the faults in the work as much as possible and improve the operation rate

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