 What Are the Faults of AC Servo Motors That Need to Be Repaired?

1. AC servo motor maintenance movement phenomenon

There is movement during feeding, and the speed measurement signal is unstable, such as a crack in the encoder; the terminal is in poor contact, such as loose screws, etc.; It is caused by the backlash of the feed drive chain or excessive servo drive gain.

2. AC servo motor maintenance crawling phenomenon

Most of them occur in the acceleration stage of starting or low-speed feed, and are generally caused by factors such as poor lubrication of the feed transmission chain, low gain of the servo system, and excessive external load.

In particular, it should be noted that the coupling used for the connection between the AC servo motor and the ball screw, due to loose connection or defects of the coupling itself, such as cracks, causes the rotation of the ball screw and the servo motor to be asynchronous, so that the feed motion is fast and slow.

3. AC servo motor maintenance vibration phenomenon

When the machine tool is running at high speed, vibration may occur, and an overcurrent alarm will be generated at this time. Machine tool vibration problems generally belong to speed problems, so speed loop problems should be looked for.

4. AC servo motor maintenance torque reduction phenomenon

When the servo motor runs from the rated operating torque to high speed, it is found that the torque will suddenly decrease, which 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 will increase. Therefore, before using the servo motor correctly, it is necessary to check the load of the motor.

5. AC servo motor maintenance position error phenomenon

When the servo shaft moves beyond the position tolerance range, the servo driver will have a "4" position out-of-tolerance alarm. The main reasons are: the tolerance range set by the system is small; the servo system gain is not set properly; the position detection device is polluted; the cumulative error of the feed transmission chain is too large, etc.

6. The phenomenon that the AC servo motor does not turn during maintenance

In addition to connecting the pulse + direction signal from the CNC system to the servo driver, there is also an enabling control signal, which is generally DC + 24V relay coil voltage.

If the servo motor does not rotate, the commonly used diagnosis methods are: check whether the CNC system has pulse signal output; The servo motor confirms that the brake has been opened; the drive is faulty; the servo motor is faulty; the servo motor and the ball screw are connected, the coupling is invalid or the key is disengaged, etc.