HEIDENHAIN TNC 426B (280 472) Touch Probe Cycles - Manual (Page 145)

HEIDENHAIN TNC 426, TNC 430 133
5.3 T
y
pes of Digitizing
U U U U Tolerance (M): The TNC stores only those digitized positions whose
distance from a straight line defined by the last two probe points
exceeds the programmed tolerance. This ensures a high density of
digitized positions for contours with sharply curved surfaces, and as
low a density as possible for contours with flat surfaces. An input
value of zero means that the digitized positions are output in the
programmed probe point interval. Input range: 0 to 0.9999 mm
U U U U Feed rate reduction at edges (M): Answer the dialog question
with NO ENT. The TNC enters a value automatically.
Unidirectional line digitizing
n Triggering touch probe: Digitizing cycle 8 LINE
n Measuring touch probe: Digitizing Cycle 18 LINE
The LINE cycle scans and digitizes a 3-D contour in a single direction
in a series of parallel lines.
With measuring touch probes, this cycle is used mainly for digitizing
with a rotary axis. See “Digitizing with a Rotary Axis.”
With triggering touch probes, this cycle is best suited for digitizing
relatively flat surfaces which are to be consistently up-cut or climb
milled without prior evaluation of the digitized data.
In this cycle, the touch probe moves in the positive direction of the
axis entered under DIRECTION. When the touch probe reaches the
MAX coordinate of this axis, it returns to clearance height. It then
moves at rapid traverse back to the beginning of the next line and from
there in the negative probe axis direction to the height for feed rate
decrease. From this point it continues traveling at the probing feed
rate until it contacts the 3-D contour. This process is repeated until the
entire range has been scanned. The paths of traverse in the LINE cycle
are illustrated in the figure at lower right.
Once the entire range has been scanned, the touch probe returns to
the clearance height.
When you are digitizing with the measuring touch probe, the TNC
stores positions at which sharp changes in direction have occurred. Up
to 1000 positions per line can be stored. In the next line, the TNC
automatically reduces the probe feed rate in the vicinity of such
positions. This behavior improves the scanning results.
The feed rate reduction is effective only if the number of
points at which the feed rate must be reduced does not
exceed 1000 points in a digitizing line.
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