
PROGRAMMING20. AXIS CONTROL FUNCTIONS
B–63534EN/02
548
The Z–axis (axial feed axis) is usually the third axis. However, any axis
can be set as the Z–axis by setting the corresponding parameter
appropriately (parameter No. 7709).
The servo delay is proportional to the speed of the hob axis. Therefore,
in a cycle where rough machining and finish machining are performed at
different hob axis speeds, compensation for the servo delay is required.
The servo delay is calculated as follows:
E= {(
60
Fc
) (
Ks
1
+C:M+L) +Sup} N
where
E:C–axis servo delay compensation (deg). . .
Fc : C–axis speed when G83 is specified (deg/min). . .
Ks : Servo loop gain (LPGIN of parameter No. 1825)
(sec
–1
). . .
C : Delay incurred in the CNC (sec). . .
M : Delay compensation magnification 1 in the CNC
(SVCMP1 of parameter No. 7715)
L : Delay incurred by smoothing, as specified by
parameter No. 7701 (sec). . .
Sup : Remaining pulse error caused by acceleration/
deceleration (deg). . .
N:C–axis servo delay compensation magnification 2
(SVCMP2 of parameter No. 7714)
When the hob axis speed is changed, C–axis servo delay compensation
is performed using the following two methods:
S Compensation is specified both before and after the speed is
changed. Each time G83 is specified, compensation for the delay
at that time is applied.
S Before the speed is changed, the servo delay is recorded. After the
speed is changed, compensation for the difference between the
recorded delay and that observed when the command is specified
is performed.
The latter method, in which the compensation before speed change is
recorded, can be used by setting bit 5 (DLY) of parameter No. 7701 to 1.
This method, in comparison with that where the amount of compensation
is not recorded, offers the advantage of processing being possible at
higher speeds.
D Setting the helical gear
axial feed axis
D C–axis servo delay
compensation (G82, G83,
G84)