HEIDENHAIN TNC 426 B, User Manual

Page: 113 / 362

97 HEIDENHAIN TNC 426 B, TNC 430
You can enter the position data in absolute or incremental
coordinates and in Cartesian or polar coordinates.
The TNC does not check whether the programmed contour will be
damaged when moving from the actual position to the auxiliary
point P
H
. Use the test graphics to simulate approach and departure
before executing the part program.
When approaching the contour, allow sufficient distance between
the starting point P
S
and the first contour point P
A
to assure that the
TNC will reach the programmed feed rate for machining.
The TNC moves the tool from the actual position to the auxiliary
point P
H
at the feed rate that was last programmed.
Radius compensation
The tool radius compensation is programmed together with the
first contour point P
A
in the APPR block. The DEP blocks
automatically remove the tool radius compensation.
Contour approach without radius compensation: If you program the
APPR block with R0, the TNC will calculate the tool path for a tool
radius of 0 mm and a radius compensation RR! The radius
compensation is necessary to set the direction of contour approach
and departure in the APPR/DEP LN and APPR/DEP CT functions.
Approaching on a straight line
with tangential connection: APPR LT
The tool moves on a straight line from the starting point P
S
to an
auxiliary point P
H
. It then moves from P
H
to the first contour point P
A
on a straight line that connects tangentially to the contour. The
auxiliary point P
H
is separated from the first contour point P
A
by the
distance LEN.
ú
Use any path function to approach the starting point P
S
.
ú
Initiate the dialog with the APPR/DEP key and APPR LT
soft key:
ú
Coordinates of the first contour point P
A
ú
LEN: Distance from the auxiliary point P
H
to the first
contour point P
A
ú
Radius compensation for machining
Example NC blocks
7 L X+40 Y+10 R0 FMAX M3
8 APPR LT X+20 Y+20 Z-10 LEN15 RR F100
9 L X+35 Y+35
10 L ...
Abbreviation Meaning
APPR Approach
DEP Departure
L Line
C Circle
T Tangential
(smooth connection)
N Normal (perpendicular)
Approach P
S
without radius compensation
P
A
with radius comp. RR, distance P
H
to P
A
: LEN=15
End point of the first contour element
Next contour element
X
Y
20
10
20
P
A
RR
P
S
R0
15
P
H
RR
RR
40
35
35
6.3 Cont
our
Appr
oac
h and Depar
tu
re
Gkap6.pm6 30.06.2006, 07:04 97
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