Siemens SINUMERIK 840D sl Function Manual page 182

K6: Contour tunnel monitoring
4.3 Programmable contour accuracy
Parameterization
Contour accuracy
The maximum contour error for the path of the geometry axes on curved contours is determined
by:
● For MD20470 $MC_CPREC_WITH_FFW = 2 with the setting data:
SD42450 $SC_CONTPREC (contour accuracy)
● For MD20470 $MC_CPREC_WITH_FFW = 3 with the contour tolerance programmed with
CTOL.
The smaller the value and the lower the K
feedrate on curved contours is lowered.
Minimum path feedrate
The user can use the following setting data to specify a minimum path feedrate for the
"Programmable contour accuracy" function:
SD42460 $SC_MINFEED (minimum path feed with CPRECON)
The feedrate will not limited below this value, unless a lower F value has been programmed
or the dynamic limitations of the axes force a lower path velocity.
Time constant for the programmable contour accuracy
The equivalent time constant for the MD20470 = 2 or 3 functional versions (see "Configuration")
is entered in the machine data:
MD32415 $MA_EQUIV_CPREC_TIME (time constant for the programmable contour
accuracy)
MD32415 must contain that jerk filter time constant (MD32410 $MA_AX_JERK_TIME) for
which the contour error for active feedforward control is negligibly small.
Programming
The "programmable contour accuracy" can be activated and deactivated in the part program
with the CPRECON and CPRECOF modal G functions.
Example:
Program code
N10 G0 X0 Y0
N20 CPRECON
N30 G1 G64 X100 F10000
N40 G3 Y20 J10
N50 G1 X0
...
N100 CPRECOF
N110 G0 ...
182
factor of the geometry axes, the greater the path
v
Comment
; Activate the "programmable contour accuracy".
; Machining with10 m/min in the continuous-path mode.
; Automatic feed limitation in circular block
; Feedrate again without limitation (10 m/min).
; Deactivate the "programmable contour accuracy".
Function Manual, 01/2015, 6FC5397-2BP40-5BA2
Special functions