Common Fault and Repair of Servo Motor System

The detection device is an important part of the CNC machine tool servo system to detect the displacement and speed of each control shaft. In actual use, the detection device malfunctions often due to wear and contamination, which causes the servo motor system to not drive the machine to run normally.

1. mechanical oscillation (when acceleration / deceleration)

The common causes of such failures are:

① The pulse encoder is faulty. At this point should check the speed detection unit feedback line terminal voltage is a certain voltage drop, if the decline indicates that the pulse encoder is bad, replace the encoder;

② pulse encoder cross joint may be damaged, resulting in shaft speed and the detected speed is not synchronized, replace the coupling;

③ speed generator failure. Repair, replace tachometer. Maintenance practice, the speed machine brush wear, jamming failure more, then should remove the tachometer brush, with a sandpaper sanding a few times, while cleaning the commutator dirt, servo motor and then re-installed.

2. mechanical movement exceptionally fast (speed)

Such as failure, should check the position control unit and speed control unit at the same time, should also check: ① pulse encoder wiring is wrong; ② pulse encoder coupling is damaged; ③ check the tachogenerator terminal servo motor is reversed And the excitation signal line is wrong.

3. The spindle can not be moved or moved in place

Such a fault, should check the orientation control circuit settings adjustment, check the orientation board, spindle control printed circuit board adjustment, but also check the position detector (encoder) output waveform is normal to determine the encoder is good or bad ( Should pay attention to the normal equipment in the normal measurement of the encoder output waveform, in order to check when the fault).

4. Vibration when the axis is fed

Should check the motor coil, mechanical feed screw with the motor connection, servo system, pulse encoder, coupling, tachometer.

5. An NC error alarm appears

NC alarm due to program error, operation error caused by the alarm. Such as FANUC6ME system Nc 090.091 alarm, the reasons may be: ① main circuit failure and feed rate is too low caused by ② pulse encoder bad; ③ pulse encoder power supply voltage is too low (at this time to adjust the power supply 15V voltage, so that the main circuit The voltage on the + 5V terminal of the board is within 4.95-5.10V); ④ does not input a pulse signal of the pulse encoder and can not normally return to the reference point.