Siemens sinumerik 840d Programming Manual page 283

04.00
8
840D
NCU 572
NCU 573
3D tool offset, tool change
A new tool with changed dimensions (R, r, a) or a
different shape may be specified only through
programming G41 or G42 (transition G40 to G41 or
G42, reprogramming of G41 of G42).
This rule does not apply to any other tool data, e.g.
tool lengths, so that tools to which such data apply
can be fitted without reprogramming G41 or G42.
Correction of the path
With respect to face milling, it is advisable to
examine what happens when the contact point
"jumps" on the tool surface as shown in the example
on the right where a convex surface is being
machined with a vertically positioned tool.
As a general rule, it is advisable to select a tool
shape and tool orientation that are suitable for
producing the required surface profile.
The application shown in the example should
therefore be regarded as a borderline case.
This borderline case is monitored by the control that
detects abrupt changes in the machining point on
the basis of angular approach motions between the
tool and normal surface vectors. The control inserts
linear blocks at these positions so that the motion
can be executed.
These linear blocks are calculated on the basis of
permissible angular ranges for the side angle stored
in the machine data.
The system outputs an alarm if the limit values
stored in the machine data are violated.
 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
Single point
8-283