The inertia matching principle of servo feed system means that when selecting servo motor, the inertia of motor and the inertia of load (converted into motor shaft) should be in a reasonable proportion to ensure the rapid response and stability of servo system. Generally speaking, the smaller the inertia ratio, the higher the response speed of the servo system, but it will also increase the acceleration and deceleration torque and power demand of the motor, and vice versa.
The torque matching principle of servo feed system means that when selecting servo motor, the torque of motor should meet the torque demand of load, including continuous running torque, acceleration and deceleration torque, cutting load torque and so on. Generally speaking, the continuous running torque of motor should not exceed 80% of the rated torque of motor, and the acceleration and deceleration torque of motor should not exceed the maximum torque of motor.
To sum up, when selecting servo motors, we should follow the principle of inertia matching and choose the appropriate inertia ratio according to different applications and requirements. Also follow the principle of torque matching. When calculating the load torque, factors such as gravity, friction, cutting force and transmission efficiency of the load should be considered.
Servo feed system:
Servo feed system refers to the transmission device used to realize the feed movement of CNC machine tools, which consists of servo motor, feed transmission system and feedback device. Servo motor is based on the command signal of numerical control device, after power amplification and shaping treatment, it produces corresponding torque and speed, and drags the moving parts such as worktable or tool rest of machine tool for linear or angular displacement.
The feed transmission system refers to the transmission chain composed of gears, pulleys, ball screws and other mechanical elements, which converts the rotary motion of the servo motor into the required linear or angular displacement motion and changes the direction, speed and torque of the motion. The feedback device is used to detect the actual position or speed of the moving part and compare it with the command signal to generate an error signal, which is used to adjust the output of the servo motor.
The function of the servo feed system is to convert the digital command signal of the numerical control device into the displacement or speed of the executive part of the machine tool, so as to realize the cutting of the numerical control machine tool. The performance of servo feed system directly affects the accuracy, speed and stability of CNC machine tools. Therefore, the servo feed system is required to have good stability, accuracy and quick response.