HEIDENHAIN TNC 426, User Manual

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136 6 Programming: Programming Contours
6.3 Cont
our Appr
oac
h
and Depar
tur
e
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 to the first contour point P
A
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.
U
Use any path function to approach the starting point P
S
.
U Initiate the dialog with the APPR/DEP key and APPR CT soft key:
U
Coordinates of the first contour point P
A
U
Radius R of the circular arc
n
If the tool should approach the workpiece in the
direction defined by the radius compensation: Enter
R as a positive value.
n
If the tool should approach the workpiece opposite
to the radius compensation:
Enter R as a negative value.
U
Center angle CCA of the arc
n
CCA can be entered only as a positive value.
n
Maximum input value 360°
U
Radius compensation RR/RL for machining
Example NC blocks
Approaching on a circular arc 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 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.
U Use any path function to approach the starting point P
S
.
U Initiate the dialog with the APPR/DEP key and APPR LCT soft key:
U Coordinates of the first contour point P
A
U Radius R of the circular arc. Enter R as a positive value.
U Radius compensation RR/RL for machining
X
Y
10
20
P
A
RR
P
S
R0
P
H
RR
RR
40 10
CCA=
180°
R10
35
20
7 L X+40 Y+10 RO FMAX M3 Approach P
S
without radius compensation
8 APPR CT X+10 Y+20 Z-10 CCA180 R+10 RR F100 P
A
with radius comp. RR, radius R=10
9 L X+20 Y+35 End point of the first contour element
10 L ... Next contour element
X
Y
10
20
P
A
RR
P
S
R0
P
H
RR
RR
40 10
R10
35
20