Free-Form Surface Mode: Extension Function - Siemens SINUMERIK 840D sl Function Manual

B1: Continuous-path mode, Exact stop, Look Ahead
4.3 Continuous-path mode
Supplementary conditions
Axis-specific feed stop/axis disable
Axis-specific feed stop and axis-specific axis disable are ignored by LookAhead.
If an axis is to be interpolated that should on the other hand be made stationary by axis-specific
feed stop or axis disable, LookAhead does not stop path motion before the block in question
but decelerates in the block itself.
If this response is not wanted, an axis-specific feed stop can be transferred to a channel via
the PLC to stop the path immediately (see also Section "Clamping monitoring (Page 86)").
4.3.4.2

Free-form surface mode: Extension function

Function
The "Free-form surface mode: Extension function" is an extension of the Look Ahead standard
functionality and is used to calculate the path velocity profile during free-form surface
processing (see also Section "Free-form surface mode: Basic functions (Page 224)").
Its use optimizes the continuous-path mode as follows:
● Symmetry between the acceleration and deceleration profiles
● Uniform acceleration process, even with changing jerk or acceleration limits
● Uniform acceleration process of target velocity profiles, irrespective of the degree to which
they can or cannot be started with the specified dynamic response limit
● Look Ahead braking to lower setpoint velocities
Uniformity and compliance with the dynamic response limit guarantee that the setpoint velocity
profiles are smoothed to a homogeneous velocity profile on the part. This serves to minimize
the effect of following errors on the quality of the surface.
Advantages
● Greater uniformity in the surface of the workpiece
● Lower machine load
Applications
The "Free-form surface mode: Extension function" is used to process workpieces which
primarily comprise free-form surfaces.
Note
As better results are not achieved for standard processing applications, standard Look Ahead
functionality should be used in these cases.
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Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Basic Functions