6 common fault problems encountered by servo motors

Servo motors can control speed and position very accurately, and can convert voltage signals into torque and speed to drive the controlled object. The rotor speed of the servo motor is controlled by the input signal and can react. In the automatic control system, it is used as an actuator and has the characteristics of small electromechanical time constant, high linearity, and starting voltage. It can convert the received electrical signal into angular displacement or angular velocity output on the motor shaft. There will be many faults during use. The following Zhongling Technology editor will list the common faults for everyone.

1. Servo motor maintenance movement phenomenon

There is a phenomenon of movement during feeding, and the speed measurement signal is unstable, such as cracks in the encoder; poor contact of the terminal, such as loose screws, etc. When the movement occurs at the moment of switching from positive direction movement to reverse direction movement, it is generally caused by the reverse clearance of the feed transmission chain or excessive servo drive gain;

2. Servo motor maintenance creeping phenomenon

Most of them occur in the starting acceleration section or low-speed feeding, which is generally caused by factors such as poor lubrication of the feed transmission chain, low servo system gain and excessive external load. In particular, it should be noted that the coupling used to connect the servo motor and the ball screw is loose or the coupling itself has defects, such as cracks, which causes the ball screw and the servo motor to rotate out of sync, causing the feed movement to speed up and slow down;

3. Servo motor maintenance vibration phenomenon

When the machine tool is running at high speed, it may generate vibration, which will generate an overcurrent alarm. The vibration problem of the machine tool is generally a speed problem, so the speed loop problem should be found;

4. Servo motor maintenance torque reduction phenomenon

When the servo motor changes from rated stall torque to high-speed operation, the torque suddenly decreases. This is caused by the heat dissipation damage of the motor winding and the heating of the mechanical part. At high speed, the temperature rise of the motor increases. Therefore, the correct use of the servo motor must verify the load of the motor;

5. Servo motor maintenance position error phenomenon

When the servo axis moves beyond the position tolerance range, the servo driver will have a position error alarm. The main reasons are: the system tolerance range is small; the servo system gain is improperly set; the position detection device is contaminated; the feed transmission chain has too large accumulated error, etc. The official account "Mechanical Engineering Collection" is a gas station for engineers!

6. Servo motor does not rotate after maintenance

In addition to the pulse + direction signal, the CNC system also has an enable control signal to the servo drive, which is generally a DC + 24 V relay coil voltage. If the servo motor does not rotate, the common diagnostic methods are: check whether the CNC system has pulse signal output; check whether the enable signal is connected; observe the system input/output status through the LCD screen to see if it meets the start conditions of the feed axis; confirm that the brake is on for the servo motor with electromagnetic brake; the driver is faulty; the servo motor is faulty; the coupling between the servo motor and the ball screw fails or the key is disengaged, etc.