PROGRAMMING15. COMPENSATION FUNCTION
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When machining of the step is commanded by circular machining in the
case of a program containing a step smaller than the tool radius, the path
of the center of tool with the ordinary offset becomes reverse to the
programmed direction. In this case, the first vector is ignored, and the tool
moves linearly to the second vector position. The single block operation
is stopped at this point. If the machining is not in the single block mode,
the cycle operation is continued. If the step is of linear, no alarm will be
generated and cut correctly. However uncut part will remain.
S
The first vector is ignored
Tool center path
Programmed path
Workpiece
Center of the circular
machining
An overcutting will result if the first vector is not ignored.
However, tool moves linearly.
Linear movement Stop position after execution of a single block
Cutter compensation C is not performed for commands input from the
MDI. However, when automatic operation using the CNC tape composed
of absolute commands is temporarily stopped by the single block
function, MDI operation is performed, then automatic operation starts
again, the tool path is as follows :
In this case, the vectors at the start position of the next block are translated
and the other vectors are produced by the next two blocks. Therefore,
from next block but one, cutter compensation C is accurately performed.
V
B2
V
B1
V
C1
’
V
C1
V
C2
V
B1
’
V
B2
’
P
B
P
A
P
B
’
P
C
P
D
Command
for MDI
When position P
A
, P
B
, and P
C
are programmed in an absolute command,
tool is stopped by the single block function after executing the block from
P
A
to P
B
and the tool is moved by MDI operation. Vectors V
B1
and V
B2
are translated to V
B1
’ and V
B2
’ and offset vectors are recalculated for the
vectors V
C1
and V
C2
between block P
B
–P
C
and P
C
–P
D
.
However, since vector V
B2
is not calculated again, compensation is
accurately performed from position P
C
.
D Machining a step smaller
than the tool radius
15.2.7
Input Command from
MDI