
B--63003EN--1/02
14. MEASUREMENT
1171
(2) Type B: The deviation is assumed to be a sum of the number of
remaining pulses due to acceleration/deceleration caused
when the skip signal is turned on, and the positional error.
Directioninwhichthetool
moves
High--speed
skip signal
Origin of the coordinate
system
Pnc
PQ
Position where
the tool actually
stopped
Position of the tool when
the skip signal was input
Pnc : Position where the tool actually stopped after the skip signal was
input [mm/inch]
P : Distance to be measured [mm/inch]
Q : Servo delay [mm/inch]
Under the conditions shown above, the NC calculates the following
equation using parameter SEA (bit 0 of parameter No. 6201) or SEB (bit
1 of parameter No. 6201):
P=Pnc--Q
For type A (SEA bit 0 of parameter No. 6201 is “1”), the deviation is
calculated by:
Q=Fm× 1/60 × (α × Tc/1000 + Ts/1000)
where
Fm : Feedrate [mm/min or inch/min]
Tc : Cutting time constant [msec]
Parameter No. 1622: Exponential acceleration/deceleration
Parameter No. 1628: Linear acceleration/deceleration after
interpolation
If parameter SKF (bit 7 of parameter No. 6200) = 0, Tc = 0.
Ts : Servo time constant [msec]
Assuming that the loop gain (parameter No. 1825) is G (unit: 1/s):
Ts = 1000/G
∼ : = 1 Exponential acceleration/deceleration
= 1/2 Linear acceleration/deceleration after interpolation