
B–63522EN/02
15. ACCURACY COMPENSATION
FUNCTION
NC FUNCTION
223
Suppose a table having a ball thread in the Y–axis direction which is
placed on a ball thread in the X–axis direction. When the ball thread in
the X–axis direction has a constant slope because of deflection and so
forth, the Y–axis that moves on the X–axis ball thread has an influence
of the slope of the X–axis ball thread. As a result, the accuracy of the
Y–axis lowers (Fig. 15.5 (a)).
When straightness compensation is used where the X–axis is set as the
movement axis and the Y–axis set as the compensation axis, the Y–axis
(the compensation axis) position is compensated according to the X–axis
(the movement axis) position, which can improve the accuracy (Fig. 15.5
(b)).
X–axis
P1, P2, P3, P4 : Points on the movement axis
Structurally, the locus of portion B that connects the X–axis and Y–axis
is influenced by the slope of the X–axis. When a movement from P1
to P4 along only the X–axis is specified without straightness com-
pensation, the locus of point A on the Y–axis is influenced by the slope
of the X–axis.
P1 P4
A
B
P3P2
Locus of
portion B
Locus of point A
Y–axis
Fig. 15.5 (a)
Explanations