Specialized Concentrated Focused
of pulse is needed, and neither is the reducing amount related to feed direction. In software
compensation, correction of each point on the error curve should be tabulated and saved to the
system memory. Then auto compensation for coordinates of each point is available in running, so as to
improve machine precision.
Backlash Compensation
Hysteresisis caused by forward and reverse clearance. Assume that driving shaft drives driven
shaft in negative (CW) rotation, servo motor will be idling without moving worktable because of
mechanical driving chain backlash, when the driving shaft suddenly begins CCW rotation (positive
motion). After staying at a certain position for some time, the worktable will move backward with the
driving shaft. The same situation will occur when the direction of the driving shaft changes again. We
call it Hysteresis. If pitch error doesn’t exist, namely under ideal condition, the moving curve of
worktable is shown in Fig. 6-13 (A), in which the horizontal section is the curve without worktable
movement during the idling of servo motor. The actual moving curve of worktable is shown in Fig. 6-13
(B).
L (Actual value)
L (Actual value)
S (Nominal value)
S (Nominal value)
A Hysteresis feature
B Actual moving curve
Fig. 6-13 Analysis of backlash
To put it in a simply way: because spindle is generally fixed on the screw whose outer wire and the
inner wire on the outer wire cannot be completely matched, the spindle needs to finish the screw
clearance in the last direction when reversing its moving direction. The compensation for the clearance
is called backlash compensation.
Measuring Method and Compensation Method
Backlash can be measured by a specialized gauge. Firstly, fix the gauge besides the spindle and
turn its pointer to the zero position. Secondly, manually move the spindle “a” mm in one direction and
move reversely the same “a” mm. Read the result of gauge, namely the actual moving distance “b” mm,
and calculate the backlash, (a-b) mm.
Input and set the obtained compensation value to the parameter “AxisBacklash”.
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