HEIDENHAIN TNC 640 (34059x-04) ISO programming - Manual (Page 206)

Programming: Programming contours
6.3 Approaching and departing a contour
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206
TNC 640 | User's Manual for DIN/ISO Programming | 3/2014
Approaching on a circular path with tangential
connection:
APPR CT
The tool moves on a straight line from the starting point P
S
to an
auxiliary point P
H
. It then moves from PH to the first contour point
PA following a circular arc that is tangential to the first contour
element.
The arc from P
H
to P
A
is determined through the radius R and
the center angle CCA. The direction of rotation of the circular arc
is automatically derived from the tool path for the first contour
element.
Use any path function to approach the starting point P
S
.
Initiate the dialog with the APPR/DEP key and APPR CT soft key:
Coordinates of the first contour point P
A
Radius R of the circular arc
If the tool should approach the workpiece in the
direction defined by the radius compensation:
Enter R as a positive value
If the tool should approach from the workpiece
side: Enter R as a negative value.
Center angle CCA of the arc
CCA can be entered only as a positive value.
Maximum input value 360°
Radius compensation G41/G42 for machining
Approaching on a circular path with tangential
connection from a straight line to the contour:
APPR LCT
The tool moves on a straight line from the starting point P
S
to
an auxiliary point P
H
. It then moves to the first contour point P
A
on a circular arc. The feed rate programmed in the APPR block is
effective for the entire path that the TNC traversed in the approach
block (path P
S
to P
A
).
If you have programmed the coordinates of all three principal axes
X, Y and Z in the approach block, the TNC moves the tool from the
position defined before the APPR block simultaneously in all three
axes to the auxiliary point PH and then, only in the working plane,
from P
H
to P
A
.
The arc is connected tangentially both to the line P
S
–P
H
as well
as to the first contour element. Once these lines are known, the
radius then suffices to completely define the tool path.
Use any path function to approach the starting point P
S
.
Initiate the dialog with the APPR/DEP key and APPR LCT soft
key:
Coordinates of the first contour point P
A
Radius R of the circular arc. Enter R as a positive
value
Radius compensation
G41/G42 for machining