Common faults of servo motor and their solutions

Servo motor can make the control speed and position accuracy very accurate, and can convert the voltage signal into torque and rotational speed to drive the controlled object. Servo motor rotor speed is controlled by input signal, and can respond quickly. In automatic control system, it is used as executive element, and has the characteristics of small electromechanical time constant, high linearity, starting voltage, etc., which can convert the received electric signal into angular displacement or angular velocity output on the motor shaft, and there will be many failures during use. Here are some examples.

1. Bearing failure is one of the most common motor failures. As the most important wear parts in servo motors, more than half of servo motor failures are usually attributed to bearing problems. Its concrete manifestations are varied, ranging from shaking and abnormal noise when the motor rotates to jamming of the motor shaft. It is worth noting that if the bearing failure is not dealt with in time, it will usually bring secondary damage. For example, the rusted debris of the bearing flies into the brake or motor encoder, causing more serious losses.

Countermeasures: ① When using servo motor, it is not allowed to exceed the rated load for a long time; ② For the occasions with shaft current, add conductive brushes or use motors with insulated bearings; ③ Preventive maintenance of servo motor.

2. When the motor application (especially the connection between the motor shaft and mechanical equipment) is exposed to polluted environment, the servo motor usually needs to be equipped with oil seals. The shaft industrial skeleton oil seal can block pollutants (oils and impurities) to prolong the life of the motor. The shaft is easy to wear, so it needs regular inspection and replacement.

Countermeasures: Preventive maintenance; According to the usage, it is recommended to replace it every 3 months, and the longest time is no more than 12 months.

3. When the winding fails, a part of the motor will be short-circuited, resulting in burning inside the motor.

Countermeasures: ① When using servo motor, it is not allowed to exceed the rated load for a long time; ② Monitor the current and the accumulation of current with time; ③ Monitor the winding temperature.

4. Unlike asynchronous motors, the rotors of servo motors are usually composed of permanent magnets. The permanent magnet magnetic sheet is fixed on the rotating shaft of the motor by overlaying or embedding.

Countermeasures: ① Run under rated load; ② Avoid accidental collision.

5. Most medium and small power servo motors are self-cooled. For servo motors with high power or special applications, air cooling or liquid cooling is also common.

Countermeasures: ① Add filter screens for fans and replace them regularly; ② Check the cooling device regularly.

6. Connecting the motor shaft requires torsional rigid coupling or reinforced belt. After the motor works for a period of time, frequent acceleration and deceleration can cause the coupling or belt to loosen or slip, which should be checked again.

Countermeasures: Therefore, it is strictly forbidden to use tools to knock the shaft, coupling or pulley during installation or disassembly. When trying to remove any equipment from the motor shaft, use hydraulic device to eject it from the shaft end.

As a high-precision electronic device, in addition to standardization in use, daily maintenance also needs attention.