Siemens SINUMERIK 840D sl Function Manual page 158

Brief Description
Smoothing the path velocity
"Smoothing the path velocity" is a function especially for applications (such as high speed
milling in mold and die production) that require an extremely steady path velocity.
Deceleration and acceleration processes that would cause high-frequency excitations of
machine resonances are avoided with the "Smoothing the path velocity" function.
This results in the following advantages:
• Improved surface quality and machining time by avoiding excitation of machine
• Constant profile of path velocity and cutting rates by avoiding "unnecessary" acceleration
Dynamic response adaptation
In addition to the "Smoothing the path velocity" function, "Dynamic response adaptation" is
another function for avoiding high-frequency excitations of machine resonances while
optimizing the dynamic path response. To this end, highly frequent changes in path velocity
are automatically executed with lower jerk or acceleration values than the dynamic response
limit value parameters assigned in the machine data.
Thus, with low-frequency changes in path velocity, the full dynamic response limit values
apply, whereas with high-frequency changes, only the reduced dynamic response limit
values act due to the automatic dynamic response adaptation.
NC block compressor
When a workpiece design is completed with a CAD/CAM system, the CAD/CAM system
generally also compiles the corresponding part program to create the workpiece surface. To
do so, most CAD/CAM systems use linear blocks to describe even curved sections of the
workpiece surface. Many interpolation points are generally necessary to maintain the
required contour accuracy. This results in many linear blocks, typically with very short paths.
The "NC block compressor" function uses polynomial blocks to perform a subsequent
approximation of the contour specified by the linear blocks. During this process, an
assignable number of linear blocks is replaced by a polynomial block. Furthermore, the
number of linear blocks that can be replaced by a polynomial block also depends on the
specified maximum permissible contour deviation and the contour profile.
Use of polynomial blocks provides the following advantages:
• Reduction of the number of required part program blocks for describing the workpiece
• Higher maximum path velocities
Combine short spline blocks
A spline defines a curve, which is formed from polynomials of 2nd or 3rd degree. With spline
interpolation, the controller can generate a smooth curve characteristic from only a few
specified interpolation points of a set contour.
References:
/PGA/ Programming Manual, Advanced, Special motion commands,
Section: Spline interpolation
6
resonances.
processes, i.e., acceleration processes that do not greatly improve the program run time.
contour
Basic logic functions: Continuouspath Mode, Exact Stop, LookAhead (B1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0