Basic Measures to Eliminate Oscillation of CNC Lathe

The CNC lathe guide rail is the benchmark for the relative movement position of the main parts of the machine tool, and its accuracy directly affects the relative position relationship between the machine tool forming movements. The error of the machine tool guide rail mainly includes the straightness error of the horizontal plane and the vertical plane of the guide rail and the parallelism error of the front and rear guide rails on the vertical plane. Studies have shown that the thermal deformation of the guide rail will cause the swelling of the guide rail surface, the inclination of the guide rail edge, the deflection of the guide rail and the linear positioning error. After the thermal deformation, the movement of the worktable on the guide rail will affect the relative position of the turning tool and the workpiece, thereby affecting the machine tool. Precision and processing quality of the workpiece. Technical research in this area needs further development.

1. Oscillation caused by closed-loop servo system: Some CNC servo systems use semi-closed-loop devices. Full-closed-loop servo systems must adjust their parameters on the premise that their partial semi-closed-loop systems do not oscillate, so they are similar.

2. Reduce position loop gain: There is a reference standard value in the servo system. If there is oscillation, the gain can be appropriately reduced due to the steady-state error of the system, but not too large.

3. Reduce the load inertia ratio: The load inertia ratio is usually set to about 70% of the parameters shown during vibration. If the fault cannot be eliminated, it is not suitable to continue to reduce the parameter value.

4. Add Proportional Integral (PID): Proportional integral is a multifunctional controller, which can not only effectively realize the proportional gain of current and voltage signals, but also adjust the lag of the output signal to the frontier problem. Because the output current and voltage lag behind the leading edge, oscillation failures sometimes occur. At this time, the output current and voltage phase can be adjusted by PID.

5. Customized CNC lathe manufacturers adopt high frequency suppression function: The parameter optimization method discussed above is the parameter optimization method of low frequency oscillation. Sometimes due to mechanical oscillation, the CNC system will generate high frequency harmonics in the feedback signal, so that the output torque is not constant. Cause vibration. In this case, a first-order low-pass filter can be added to the speed loop, which is a torque filter.