Machine tools with a gravity axis, such as the X-axis of the inclined bed of the horizontal lathe, the Z-axis of the CNC milling and the machining center, due to its own gravity, when the machine is powered off or the servo is ready, the electromagnetic brake or Counterweights are used to offset its own gravity, so as not to cause the gravity axis to fall, but even if it does not move for a long distance, there will be a few micrometers slide. For precision machine tools, this is undesirable. Today we use FANUC CNC system, the feed axis movement function during emergency stop, to eliminate the sliding caused by the gravity axis's own gravity, and then maintain the accuracy of the machine tool itself!
1. Function introduction
In the FANUC CNC system, when pressing the emergency stop on the operation panel, all the servo ready signals will be disconnected, and the brake of the gravity axis will also be opened, but there will be a few micrometers sliding, and the feed axis will move through the emergency stop. Function, the feed axis can move a few microns in the opposite direction during emergency stop, to eliminate the sliding of the gravity axis when the servo is disconnected, and to ensure that the position of the gravity axis of the machine tool remains unchanged before and after the emergency stop and power failure;
2. Parameter settings (this time the parameters are obtained from the Z-axis test of the vertical machining center)
N2005#6=1 BRKC set the brake control function to be valid
N2083=200 brake control timer (in milliseconds)
N2210#6#5=1,1 Set the timer until the actual emergency stop on the servo amplifier after the emergency stop signal is input in the Alpha iPS power supply module (default value is 400ms)
N2204#7=1 DBS2 Set the stop distance shortening function type 2 to be valid during emergency stop
N2373=500 Lifting amount (500um)
N2374=16 lifting time (unit: ms)
Fine-tune N2373 and N2374 according to the actual situation
3. Debugging steps
3.1 After setting the parameters, adjust the above parameters by pressing the emergency stop to observe the changes of the mechanical coordinates. Sometimes it may cause too much lift. What we require is to keep the mechanical coordinates unchanged, just to offset the fall of the gravity axis. the distance;
3.2 Mainly fine-tune N2373 and N2374 according to the actual situation
4. Summary
The length of the lift is determined by the excitation cut-off time during emergency stop. This time cannot be too long, so the lift is also in the micron level. If you want to increase the amount of improvement, you need FANUC's fallback function. The fallback function needs to be realized by a combination of hardware and software.
