One for X-axis feed, one for Y-axis feed, and one for Z-axis feed. The X, Y axis movement feed system consists of ball screw, elastic coupling, linear guide, servo motor and other components, servo motor selects INVT DB100 750W servo products. Z-axis movement feed system is also composed of ball screw, flexible coupling, linear guide, servo motor and other components, servo motor selects INVT DB100 400W servo products with brake series.
Figure 1: Control composition diagram
Figure2: GE300 software control interface3. Introduction of control methods
4. Basic debugging steps
Engraving and milling machine has higher requirements for the performance of servo; a fast dynamic response speed is required for circular interpolation.
1. In accordance with the general principles of debugging, the first step is to conduct debugging and parts processing, measuring linear interpolation and circular interpolation accuracy, the debugging will be completed after meeting the requirements.
2. if the accuracy does not meet the requirements, then continue to increase the speed loop gain and position loop gain, at this time if the motor issues a high frequency sound, you can conduct the mechanical resonance frequency measurement, and then set the mechanical resonance frequency value to notch frequency value;
3. Repeat the above steps until find the best parameter value
In general, the mechanical resonant frequency points of engraving and milling machine won’t exceed two points. When the mechanical resonance frequency is eliminated, the stiffness of servo motor can be adjusted very high, which can meet the dynamic response speed of circular interpolation of engraving and milling machine, so as to achieve the accuracy of circular interpolation.
In order to ensure the reliable, stable and correct operation of servo drive, now combined with our servo application experience, we have summarized a few servo application precautions:
1. Correct wiring: Our servo standard encoder line and motor line, the signal line between the servo drive and controller must be correctly connected, or the servo won’t run normally.
2. Correctly setting the servo control mode: As each machine application is different, so the correct setting of servo control mode is the premise of ensuring the correct operation of servo.
3. Set the electronic gear ratio correctly: Set the servo according to the electronic gear ratio set by control program. In addition, we should not set the electronic gear ratio in the case of servo enable.
Make sure the motor is well grounded and the driver is connected to device housing. On the one hand, it can avoid interference, on the other hand, it can avoid leakage.
4. Take every effort to choose shielded twisted pair as the signal line, the shielding layer is generally connected to the terminal shell
5. Pay attention to the interference problem of engraving and milling machine high-speed spindle inverter. Prevent the encoder signal and control signal from interference, the encoder line, signal line should not be tied with motor line, power line or passing the same trunking, try to keep a certain distance between them.
6. Drive installation environment requirements, because the engraving machine will produce a lot of dander while working, so user should pay attention to the driver installation environment to avoid the internal circuit damage of driver caused by dander processing.
We achieve the process requirements through the above process: processing the accuracy of a circular slice within 5 S (1 S = 10um). The stiffness is turned up by improving the notch filter and suppressing the mechanical resonance, as a result, the processing accuracy is within 4 S, best in 2 S same to Panasonic processed slices. Customers even think the effect of some slices is better than the one of Panasonic.