How to handle the machining accuracy of large CNC machining centers

When the machining accuracy of large CNC machining centers is poor, the following three aspects should be analyzed and addressed.

(1) Poor machining accuracy of parts is usually due to improper adjustment of the feed dynamics between shafts during equipment adjustment, or due to changes in the transmission chains of each axis of the CNC machining center after wear (such as gaps between screws, pitch errors, axial motion, etc. during vertical machining).

It can be processed by adjusting and correcting the gap offset from the beginning. When the dynamic tracking error is too large and an alarm is issued, it is possible to check whether the speed of the servo motor is too high; Whether the orientation detection element is protruding; Whether the contact of the directional response cable connector protrudes; Whether the corresponding analog output latch and gain potentiometer are prominent; Whether the corresponding servo drive equipment is normal.

(2) Excessive adjustment of the motion of the CNC machining center leads to poor machining accuracy, which may be due to short acceleration and deceleration times, which may appropriately extend the speed change time; It is also possible for the connection between the servo motor and the screw to be loose or have poor rigidity, and the gain of the azimuth ring can be appropriately reduced.

(3) The roundness of the double axis connecting rod exceeds the tolerance range.

a. Axial deformation of a circle

This deformation may be caused by mechanical faults. The positioning accuracy of the shaft is poor, or the clearance of the lead screw is not properly compensated, resulting in roundness error when passing through the quadrant.

b. Oblique ellipse error (ellipse in 45 degree direction)

At this point, the bearing error value of each shaft should be checked first. If the error is too large, the azimuth loop gain can be adjusted to sweep. Then check whether the interface board of the rotary transformer or induction synchronizer is adjusted correctly, and then check whether the gap between the mechanical transmission pairs is too large and whether the gap compensation is appropriate.