Bore scraping is a mechanical quality failure that motor products often encounter. Its limit state is uneven air gap , that is, the motor stator and rotor are not coaxial. Uneven air gap is a defect that the physical space of motor parts does not conform to each other. After the motor is powered on, the uneven air gap will be aggravated by the unilateral magnetic pull. When the bore scraping failure occurs, the ventilation, heat dissipation, vibration and noise performance of the motor will be affected to varying degrees.1. Several common types of chamber cleaning failure manifestations(1) There is a phenomenon of bore sweeping at both ends of the stator core, and the two are distributed diagonally, while there is a circle of friction marks at the corresponding axial position of the rotor. The main reason for this type of failure is the misalignment of the bearing system at both ends of the motor, which is closely related to the matching relationship between the motor base and the end cover.(2) There are traces of solid rubbing at one end of the stator core, and there is a circle of solid rubbing at the corresponding position of the rotor. This problem is mainly caused by the protrusion of the stator. The reason for this problem is that the core is subjected to inappropriate external force when it is pressed into the machine base. The deeper reason may be that the mold for pressing the stator into the machine base, the pressing ring of the stator part, etc. do not match, or the stator and the machine base are improperly rotated. When this problem occurs, it may also be accompanied by an electrical fault at the bottom of the stator winding slot to the ground. In addition, the possibility of repairing the motor fault is small. Even if the fault to the ground is repaired, it is very likely that the inter-turn fault of the winding will occur.(3) The problem of bore scraping in the middle of the core. This problem is mostly caused by local problems in the stator or rotor. To distinguish whether it is a stator problem or a rotor problem, you can analyze the fault characteristics. If it is a stator problem, the fault is manifested as friction marks in the local stator and a circle of the rotor. On the contrary, when there is a local problem in the rotor, the fault is manifested as a local rotor and a circle of the stator inner bore. The cause of this problem is mostly related to the processing of the stator core or rotor.
2. Causes of motor sweeping
The most basic reason why the motor has the problem of bore scraping during operation is that the motor rotor and stator are not concentric, resulting in the local gap of the motor being too small and friction between the motor bearings and the casing. This is the main cause of the bore scraping failure.1. The motor bearings are severely worn or damaged. During the operation of the motor, the bearings shake too much, resulting in the problem of bore scraping.2. The motor rotor shaft is severely bent, and during rotation, it will cause friction with the casing, resulting in a bore cleaning failure.3. If the motor end cover is not installed properly, or the positioning pin is broken, or the motor end cover is installed off-center, the problem of bore scraping may also occur.4. Foreign matter in the gap between the stator and rotor of the motor. This situation is relatively rare, but if it occurs, it will cause the motor to scrape the barrel.
3. Maintenance method of motor sweeping
What should you do if you encounter the problem of motor barrel scraping? Find out the cause of the motor barrel scraping, and then apply effective maintenance methods to solve the problem of motor barrel scraping.The bearing rotation phenomenon can also cause the motor to scrape the bore failure. In order to prevent the bearing sleeve and the end cover from rotating, some motors install special steel sheets between the sleeve and the end cover. Some motors hit the bearing up and down (the bearing should be heated for correct disassembly and assembly) or lose the anti-rotation steel sheet, which can cause the bearing rotation phenomenon.For motors with bearing rotation, do not use the chiseling method to repair the motor bearings . Instead, use the gluing method to repair the motor bearings, which will have a better effect.Recommendations: (1) Use metal glue for motors with high power and high speed; (2) Use chlorine tincture glue for motors with low power and low speed.Repair method: First clean the sleeve, add grease , then apply glue, and then reassemble the motor. If the sleeve is seriously damaged, the gap between the inner ring of the bearing and the journal or the outer ring and the end cover is large, you can use a metal sheet of appropriate thickness to pad the gap. To ensure concentricity, the metal sheet should be made into an oblique edge, and apply appropriate glue to the gap between the motor bearings, and then it can be restored to normal.Repair of motor bearings has shown that most motors can be restored to normal operation by applying appropriate glue to the gap of the motor bearings.
4. Six measures to avoid motor barrel sweeping
1. Choose high-quality motors;2. Choose high-quality bearings;3. Select lubricating grease that meets the requirements;4. Check, add and replace lubricating grease according to regulations;5. Regularly or online test the bearing temperature and vibration; if possible, perform ferrography analysis regularly;6. For large or important motors, a motor wear status monitoring and alarm device can be installed to monitor the changes in the motor's eccentricity by detecting changes in the motor's air gap magnetic field, so that problems can be discovered and repaired in a timely manner to avoid the occurrence of bore scraping problems.
XINDA