Monitoring Of Path Curvature - Siemens SINUMERIK 840D sl Function Manual

If the tool orientation at an inside corner is not constant, the change in orientation is
implemented in the same way as described in Subsection "Behavior at inside corners" for 3D
circumferential milling, i.e. the tool is moved in the corner so that it contacts the two adjacent
surfaces at the block start, block end and at two points
A 3rd-degree polynomial is used to interpolate between these 4 points.
A variable tool orientation in a block that is shortened owing to an inside corner is also treated
in the same way as described in Subsection "Behavior at inside corners" for 3D milling, i.e.
the entire change in orientation is executed in the shortened block. Consequently, the
functional relationship between path tangent, surface normal and tool orientation also
changes. This results in new, previously nonexistent singularities or impermissible side
angles (at points which are virtually singular) occurring in the shortened block. If this type of
situation is detected during processing of an inside corner, the machining operation is aborted
with an alarm. No block division takes place at the singular points since the compensatory
motions this would involve frequently cause contour violations and the change in machining
side on the tool is not generally intended or even foreseen by the user. The alarm is also
output during examination of an inside corner if the singularity occurs in the second of the two
blocks without the transition to the next block being considered. The system does not
therefore detect that a block of this type will form an inside corner in conjunction with the
following block and that the singularity would be eliminated again by the second block
reduction.
The surface normal vector n
contrast to the tool orientation, the change in orientation that may need to be executed for this
vector will not be imaged onto the reduced traversing interval. This is necessary because a
surface other than that programmed would be machined. Unlike the tool orientation, no
problems arise as the result of an abrupt change in the surface normal vector at a block
transition since it does not reflect any axis motions.
Analogously to 3D circumferential milling, (see Subsection "Behavior at inside corners"), the
two traversing blocks that form an inside corner must contain contact points. There is no
evaluation of several traversing blocks (i.e. no bottleneck detection), CDON/CDOF are not
evaluated. If no contact point can be found, the machining operation is aborted with an alarm
(risk of collision).
19.3.7

Monitoring of path curvature

The path curvature is not monitored, i.e. the system does not usually detect any attempt to
machine a concave surface that is curved to such a degree that the tool currently in use is not
capable of performing the machining operation. A possible exception are blocks that are split
owing to a singularity. The transition between the two partial blocks created after the split is
then treated like an inside corner. Except for such special cases, the user is responsible for
ensuring that only tools that can machine along the entire contour without violating it are
used.
Special Functions
Function Manual, 09/2011, 6FC5397-2BP40-2BA0
is not affected by the reduction of a block. This means that in
F
W5: 3D tool radius compensation
19.3 Face milling
1 2
/ and / of the change in orientation.
3 3
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