HEIDENHAIN TNC 620 (73498x-01) - Manual (Page 386)

386 Programming: Multiple axis machining
1
1
.6 Thr
ee-dimensional t
o
ol compensation (sof
tw
ar
e option 2)
Definition of a normalized vector
A normalized vector is a mathematical quantity with a value of 1 and a
direction. The TNC requires up to two normalized vectors for LN
blocks, one to determine the direction of the surface-normal vector,
and another (optional) to determine the tool orientation direction. The
direction of a surface-normal vector is determined by the components
NX, NY and NZ. With an end mill and a radius mill, this direction is
perpendicular from the workpiece surface to be machined to the tool
datum P
T
, and with a toroid cutter through P
T
’ or P
T
(see figure). The
direction of the tool orientation is determined by the components TX,
TY and TZ.
PT
R R R
R2
PT
PT
R2
PT'
P
T
P
SP
The coordinates for the X, Y, Z positions and the surface-
normal components NX, NY, NZ, as well as TX, TY, TZ
must be in the same sequence in the NC block.
Always indicate all of the coordinates and all of the
surface-normal vectors in an LN block, even if the values
have not changed from the previous block.
Calculate the normal vectors as exactly as possible and
output them with a sufficient number of decimal places, in
order to avoid interruptions in the feed rate during
machining.
3-D compensation with surface-normal vectors is only
effective for coordinates in the main axes X, Y, Z.
If you insert a tool with oversize (positive delta value), the
TNC outputs an error message. You can suppress the
error message with the M function M107 (see "Definition of
a normalized vector", page 386).
The TNC will not display an error message if an entered
tool oversize would cause damage to the contour.
The toolRefPoint machine parameter defines whether
the CAM system has calculated the tool length
compensation from the center of sphere P
T
or the south
pole of the sphere P
SP
(see figure).