Free-Form Surface Mode: Basic Functions - Siemens SINUMERIK 840D sl Function Manual
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B1: Continuous-path mode, Exact stop, Look Ahead
4.4 Dynamic adaptations
References
You can find detailed information about programming the G commands from G function group
59 (dynamic response mode for path interpolation) in:
References:
Programming Manual, Job Planning; Section: Path traversing behavior
4.4.6
Free-form surface mode: Basic functions
Introduction
In applications in tool and mold making, it is important that the surfaces on the workpiece are
as uniform as possible. This requirement is generally more important than the precision of the
surface of the workpiece.
Workpiece surfaces which lack uniformity can be attributable to the following causes, for
example:
● The part program for manufacturing the workpiece contains a non-uniform geometry. This,
most notably, affects the profile of the curvature and torsion.
Note
The curvature k of a contour is the inverse of radius r of the adapted circle in a contour
point (k = 1/r). The torsion is the change in curvature (first derivative).
As a result of the lack of uniformity in geometry, the machine's dynamic response limits are
reached during processing of the part program, and needless deceleration and acceleration
processes occur. Depending on the extent of the effective over-travel of the axes, this leads
to different deviations in contours.
● Needless deceleration and acceleration processes can trigger machine vibrations which
result in unwanted marks on the workpiece.
There are various options available for eliminating these causes:
● Use a CAD/CAM system
The part programs generated by CAD/CAM systems contain a very uniform curvature and
torsion profile, preventing needless reductions in path velocity.
● Specify the maximum path velocity 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 has 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)
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Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions
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