How to eliminate the vibration of CNC machine tools?

  • 2021-04-29

CNC machine tools are widely used in our country, because of its unique excellent performance by the majority of fans. But in the process of using it, there will always be some fault problems, the common one is oscillation fault. It generally occurs in the mechanical part and feed servo system. The following is about how to eliminate the vibration of this CNC machine.

There are many reasons for the oscillation, in addition to the mechanical aspects of the transmission gap, elastic deformation, friction and many other factors, the influence of the servo system parameters is also an important aspect. So how to eliminate the oscillation of CNC machine tools?

1. Reduce the gain of position loop

The proportional calculus is a multi-functional controller. It can not only gain the current and voltage signal in proportion, but also adjust the output signal to lag behind the front. Sometimes the oscillation fault occurs because the output current and voltage lag behind the front. [**]t this time, the phase of the output current and voltage can be adjusted by PID.

2. Oscillation caused by closed loop servo system

Some numerical control servo systems use semi closed loop devices, while the full closed loop servo system must adjust its parameters on the premise that the local semi closed loop system does not oscillate, so they are similar.

3. High frequency suppression function

The above discussion is about the parameter optimization method of low-frequency oscillation, and sometimes the CNC system will produce feedback signal containing high-frequency harmonics due to some mechanical oscillation reasons, which makes the output torque not constant, resulting in vibration. For this kind of high-frequency oscillation, a first-order low-pass filter, i.e. torque filter, can be added to the speed loop.

The speed command and speed feedback signal are transformed into torque signal by speed controller, and the high frequency component of torque signal is cut off by first-order filter, so as to obtain effective torque control signal. By adjusting the parameters, the frequency above 100Hz generated by the machine can be cut off, so as to achieve the effect of eliminating high-frequency oscillation.