Siemens SINUMERIK 840C - Manual (Page 406)

12.93 6 NC Machine Data (NC MD), NC Setting Data (NC SD)
6.12.1 NC setting data (NC SD)
General setting data
Dry run feedrate 0
Default value Lower input limit Upper input limit Units
0 0
1072 0000
9999 9999 (as from
SW 5)
1 000 units/min
Active on
–
If ”Dry run feedrate” is selected on the control, the tool path feedrate selected is the dry run
feedrate (mm/min (G94)) and not the programmed feedrate.
Dyn. smoothing time thread cutting 1
Default value Lower input limit Upper input limit Units
0 0 5 2 n -1 ×IPO cycle
Active on
–
Programming smoothing exponent via G92 T..
This function is used to protect the drive when cutting threads and to obtain a better speed
stability.
The feed ramp-up time until synchronization with the working spindle already running is
reached can be programmed using the command G92 T.. . The feed ramp-up time should be
matched to the running path available:
• short run-in path, short ramp-up time, low T value
• long run-in path, long ramp-up time, high T value
The programmed ramp-up time also acts as the smoothing time, i.e. the actual spindle speed
is averaged via this value an even feedrate is thus obtained.
The smoothing and feed ramp-up time depends on
• the programmed value T..
• the interpolation cycle which is set in NC MD 155; this machine data should only be
changed by a properly trained specialist.
The value T.. must be an integer. Possible values are 0...5. The following table shows which T
value must be programmed for a set interpolation cycle in order to obtain the required feed
ramp-up time:
Thread cutting with constant lead (G33)
Thread cutting with linear increasing lead (G34)
Thread cutting with linear decreasing lead (G35)
Program syntax:
N.. G33 <Coordinates of target point> <thread lead>
N.. G34 <Coordinates of target point> <initial lead> <lead change>
N.. G35 <Coordinates of target point> <initial lead> <lead change>
The action of G functions G33, G34, G35 are modal.
The programmed feedrate F has no meaning but remains modal, i.e. the feedrate is derived
internally from the actual speed value of the leading spindle.
© Siemens AG 1992 All Rights Reserved 6FC5197- AA50 6–221
SINUMERIK 840C (IA)