Friction is mainly applied to the transmission and guide of the machine tool. Due to the influence of friction, the torque required at the start of the feed axis is much greater than that required during normal operation, and the feed axis will have a relatively large following error when it starts. When two feed axes are interpolated at the same time, if the movement direction of one axis changes, when the speed passes 0, the interpolation axis will have a short time stagnation due to the change of friction state. Contour error. This phenomenon is particularly prominent when machining arc contour workpieces. At the arc conversion quadrant, one axis has reached the maximum speed and the other axis has a speed of 0. There will be a raised area Lines or dents. In order to improve the contour error of the arc across the quadrant, the GR driver adds a friction compensation function. Friction compensation can significantly improve the over-quadrant contour error caused by the influence of friction.

solution

According to the cause of the quadrant protrusion, the GR driver provides two friction compensation modes:
Low speed compensation function (position and speed mode are valid);
PA42 --- characteristic speed of low-speed compensation function (default 50, generally does not need to be adjusted);
Pa43 --- low speed compensation coefficient.
Reverse acceleration compensation (position mode is effective);
PA135 --- Reverse acceleration compensation gain;
PA136 --- Reverse acceleration compensation time.


Applications


      A customer processed an aluminum alloy bottle cap for a foreign XX perfume company. The processed product had a prominent arc-shaped quadrant protrusion, which failed to meet the acceptance criteria of the foreign company. The customer requested that the trace of the quadrant protrusion must be eliminated.
      The customer's machine tool is a Baoji TK36S flat bed hard rail lathe. The system configuration is a commonly used 980TDI system supporting GR2050 driver.
      The friction force of the flat bed hard rail lathe is relatively large. According to customer requirements, the friction compensation function is used to adjust accordingly, and the low speed compensation function is preferentially used when adjusting.
Adjustment process:
Roundness analysis using acquisition software.






From the above figure, we can see that there are four raised sharp corners where the circle passes the quadrant, the reverse jump is 0.0047mm, and the comprehensive roundness is 0.0057mm. This is the quadrant error caused by the friction of the machine tool.


Use low speed compensation function;
Adjust PA43 = 500 and perform roundness analysis again.





After using the low-speed compensation function, you can see that the four raised sharp corners of the circle through the quadrant become significantly smaller, with a reverse jump of 0.00134mm and a comprehensive roundness of 0.0019mm; the error of the arc through the quadrant has improved significantly.
      Continue to increase the PA43 = 1000 test. It is found that the improvement of the raised sharp corners in the quadrant is not much different from PA43 = 500. Change the PA43 parameter value to 500 and use the reverse acceleration compensation function.
Reverse acceleration compensation
After using the low-speed compensation function, the quadrant error has been significantly reduced. Set the reverse acceleration compensation gain to a relatively small value first;
Adjust PA135 = 20 PA136 = 100 to continue collecting data for roundness analysis.






The figure above shows that after using the low speed compensation and reverse acceleration compensation, you can see that the four raised sharp corners rounded the quadrant have become extremely slight; the reverse jump is 0.00087mm, and the comprehensive roundness is 0.0017mm.
      After the above adjustments, the customer processed again, and the raised texture on the surface of the sample passed through the quadrant was eliminated, and the product reached the acceptance standards of foreign companies.


summary

       Using the low-speed compensation function and the reverse acceleration compensation function can well improve the arc-cross quadrant raised texture caused by mechanical friction. When using it, you can use the low-speed compensation function and the reverse acceleration compensation function as required.