Dynamic Adaptations; Smoothing Of The Path Velocity - Siemens SINUMERIK 840D sl Function Manual

B1: Continuous-path mode, Exact stop, Look Ahead

4.4 Dynamic adaptations

4.4 Dynamic adaptations
4.4.1

Smoothing of the path velocity

Introduction
The velocity control function utilizes the specified axial dynamic response. If the programmed
feedrate cannot be achieved, the path velocity is brought to the parameterized axial limit values
and the limit values of the path (velocity, acceleration, jerk). This can lead to repeated braking
and acceleration on the path.
If a short acceleration takes place during a machining function with high path velocity, and is
thus followed almost immediately by braking, the reduction in the machining time is only
minimal. Acceleration of this kind can, however, have undesirable effects if, for example, it
results in machine resonance.
In some applications in mold making, especially in the case of high-speed cutting, it is desirable
to achieve a constant path velocity. In these cases, it can therefore be reasonable to sacrifice
transient acceleration processes in favor of a smoother tool path velocity.
Function
If the "smoothing the path velocity" function is active, a smoothing factor, which determines
the maximum permissible productivity loss, takes effect with a view to achieving smoother path
velocity control: Acceleration processes which contribute less than this factor to a shorter
program runtime are not performed. Account is only taken of acceleration processes whose
frequencies lie above the configurable limit frequencies of of the axes involved.
Benefits:
● Avoidance of excitations of possible machine resonance due to continuous, transient
braking and acceleration processes (in the area of less IPO cycles).
● Avoidance of constantly varying cutting rates due to acceleration which brings no significant
shortening of the program running time.
Note
The smoothing of the path velocity does not lead to contour errors.
Variations in axis velocity due to curvatures in the contour at constant path velocity may
continue to occur and are not reduced with this function.
Variations in path velocity due to the input of a new feedrate are not changed either. This
remains the responsibility of the programmer of the subprogram.
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Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions