
B–62073E–1/04 2. INTERFACE BETWEEN CNC AND PMC–NA OR NB
– 311 –
2.3.78 Chopping function
The contour of a workpiece can be ground by executing the contour program for axes other than the grind axis
(where the grindstone is attached) while keeping the grindstone moving vertically (chopping) along the grind
axis. The G81.1 command directs chopping.
G81.1Z____ Q____ R____ F____ ;
Z : Top dead point position
Q : Distance between the top dead point and bottom dead point
R : Distance between the top dead point and point R
F : Feedrate during chopping
The procedure for chopping is described below.
1 Move to point R by rapid traverse.
2 Then move to the bottom dead point at the feedrate specified by F.
3 Return to the top dead point at the feedrate specified by F.
4 Then, repeat this vertical movement (chopping) between the top dead point and bottom dead point at the
feedrate specified by F. A reset or G80 command stops chopping, and returns the grindstone to point R.
(a) Chopping hold signal (CHLD)
[Classification]
Input address
[Function] Suspends chopping.
[Operation] When this signal goes low, the control unit functions as described below.
1 When G81.1 is not specified, no action takes place.
2 When G81.1 is specified, chopping is suspended.
How chopping is suspended depends on which part of the chopping operation is in prog-
ress when this signal goes low, as described below.
i) When this signal goes low while the grindstone is moving from the top dead point to the
bottom dead point
The grindstone moves to the top dead point, then it moves to point R, and finally chopping
is stopped.
ii) When this signal goes low while the grindstone is moving from the bottom dead point to
the top dead point
The grindstone moves to the top dead point, then it moves back to the bottom dead point:
Then the grindstone is moved to point R, and finally chopping is stopped.
When this signal goes high, the control unit functions as described below.
1 When chopping is suspended, the control unit resumes chopping.
2 When chopping is not suspended, the control unit performs no operation.