Servo motors are currently used in CNC machine tools: stepper motors, DC servo motors, and AC servo motors.
The power of the servo motor depends on the load conditions. There are two kinds of loads applied to the motor shaft, namely load torque and load inertia torque. To be calculated correctly for both loads, the values should satisfy the following conditions:
(1) When the CNC lathe is running with no load, in the entire speed range, the load torque applied to the servo motor shaft should be within the continuous rated torque range of the motor, that is, it should be within the continuous torque-speed characteristic curve. workspace.
(2) The maximum load torque, loading cycle and overload time should be within the allowable range of the provided characteristic curve.
(3) The torque of the motor during acceleration or deceleration should be within the acceleration and deceleration area (or intermittent working area).
(4) For loads that require frequent starting, braking and periodic changes, it is necessary to check the torque root mean square value in one cycle, which should be less than the continuous rated torque of the CNC lathe motor.
(5) The load inertia added to the spindle motor shaft will have an impact on the sensitivity of the motor and the accuracy of the entire servo system. Usually, when the load inertia is less than the rotor inertia of the motor, the above effects are not significant, but when the load inertia reaches or even exceeds 3 times the rotor inertia, the sensitivity and response time will be greatly affected, and even the servo amplifier will not be within the normal adjustment range. work inside. Therefore, this kind of inertia should be avoided.
