Siemens sinumerik 840d Programming Manual page 285

04.00
8
840D
NCU 572
NCU 573
Intersection procedure for 3D compensation
(from SW 5)
With 3D circumferential milling, G code G450/G451
is now evaluated at the outside corners; this means
that the intersection of the offset curves can be
approached. With SW 4 a circle was always inserted
at the outside corners.
The new functionality is particularly advantageous
for typical CAD-generated 3D programs. They often
consist of short straight blocks (to approximate
smooth curves), where the transitions are almost
tangential between adjacent blocks.
Up to now, with tool radius compensation on the
outside of the contour, circles were generally
inserted to circumnavigate the outside corners.
These blocks can be very short with almost
tangential transitions, resulting in undesired drops in
velocity.
In these cases, as with 2 1/2 D radius compensation,
both of the curves involved are lengthened and the
intersection of both lengthened curves is
approached.
The intersection is determined by extending the
offset curves of both blocks and defining their
intersection a the corner in the plane perpendicular
to the tool orientation. If there is no such
intersection, the corner is handled as previously, that
is, a circle is inserted.
For more information about intersection procedure,
see /FB/ W5, 3D Tool Radius Compensation
 Siemens AG 2000. All rights reserved
SINUMERIK 840D/840Di/810D/FM-NC Programming Guide Advanced (PGA) − 04.00 Edition
8.5 Activate 3D tool offsets
840Di
Tool Offsets
8
8-285