Siemens SINUMERIK 828D Function Manual page 194

B1: Continuous­path Mode, Exact Stop, LookAhead
3.4 Dynamic adaptations
There are various options available for eliminating these causes:
• The part programs generated by the CAD/CAM system contain a very uniform curvature and torsion profile,
preventing needless reductions in path velocity.
• The maximum path velocity is determined in such a way that unwanted geometric fluctuations in the curvature
and torsion profile have no effect.
Function
"Free-form surface mode: Basic functions" can be used to make the definition of path velocity limits insensitive to
small geometric fluctuations in curvature and torsion without exceeding the machine's dynamic limits in terms of
the acceleration and jerk of the axes.
This results in the following advantages:
• Greater uniformity in the profile of the path velocity
• Greater uniformity in the surface of the workpiece
• Reduction in the processing time (if the dynamic response of the machine permits it)
Applications
The function is used to process workpieces which primarily comprise free-form surfaces.
Requirements
The function can only be activated if the requisite memory capacity is reserved during memory configuration:
MD28610 $MC_MM_PREPDYN_BLOCKS = 10
The value entered prescribes the number of blocks which have to be taken into consideration in the
determination of the path velocity (velocity preparation).
A sensible value is "10".
If MD28610 has a value of "0", only the movements of the axes in a particular block are taken into consideration
when determining the maximum velocity of the path for that block. If the geometry of neighboring blocks is also
taken into consideration when determining the velocity of the path (value > 0), a more uniform profile in path
velocity is achieved.
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Function Manual, 09/2011, 6FC5397-0BP40-2BA0
Basic Functions