Siemens SINUMERIK 840D sl Function Manual page 182

Detailed description
2.3 Continuous -path mode
Smoother path movement
If the velocity is controlled smoother and not every acceleration process is carried out, both
advantages can be achieved without any undesired extended machining time.
Decision-making criteria
The control system makes a decision based on:
• Smoothing frequency for the tool path velocity (MD)
• Tolerable loss in productivity when suppressing accelerations/decelerations (MD).
Setting parameters for path smoothing
The user can define the following parameters to set the path smoothing:
• Extending the processing time by means of machine data:
• Use of the machine data to input the resonance frequencies of the participating axes:
• Use of machine data to take into account the programmed feedrate for smoothing:
MD20460
A percentage value corresponding to the permissible extension must be specified in machine
data:
MD20460 $MC_LOOKAH_SMOOTH_FACTOR (smoothing factor for LookAhead)
The percentage value defines how much longer a machining step without accelerations may
be than the corresponding step when performing the accelerations/decelerations.
This would be a "worst-case" value, if all accelerations within the part program, except the
initial approach motion, were smoothed.
The actual extension will always be smaller, and may even be 0, if the criterion is not met by
any of the accelerations.
Values between 50 and 100% may also be entered without significantly increasing the
machining time.
30
MD20460 $MC_LOOKAH_SMOOTH_FACTOR (smoothing factor for LookAhead)
If the velocity is not accelerated, it will take longer to process this part program (see
example).
MD32440 $MC_LOOKAH_FREQUNECY (smoothing frequency for LookAhead)
Only accelerations in velocity, which clearly excite machine resonances, should be
removed.
MD20462 $MC_LOOKAH_SMOOTH_WITH_FEED (path smoothing with programmed
feedrate)
Basic logic functions: Continuouspath Mode, Exact Stop, LookAhead (B1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0