Contour Accuracy, Cprecon, Cprecof - Siemens SINUMERIK 840Di sl Programming Manual

5.7

Contour accuracy, CPRECON, CPRECOF

Function
In machining operations without feedforward control (FFWON), errors may occur on curved
contours as a result of velocity-related differences between setpoint and actual positions.
The programmable contour accuracy function CPRECON makes it possible to store a
maximum permissible contour violation in the NC program which must never be overshot.
The magnitude of the contour violation is specified with setting data $SC_CONTPREC.
The Look Ahead function allows the entire path to be traversed with the programmed contour
accuracy.
Programming
CPRECON
or
CPRECOF
Parameter
CPRECON
CPRECOF
Note
A minimum velocity can be defined via the setting datum $SC_MINFEED, which is not
undershot, and the same value can also be written directly out from the parts program via
the system variable $SC_CONTPREC.
On the basis of the value of the contour violation $SC_CONTPREC and the servo gain factor
(velocity/following error ratio) of the geometry axes concerned, the control calculates the
maximum path velocity at which the contour violation produced by the overtravel does not
exceed the minimum value stored in the setting data.
Example
N10 X0 Y0 G0
N20 CPRECON
N30 F10000 G1 G64 X100
N40 G3 Y20 J10
N50 X0
Fundamentals
Programming Manual, 11/2006, 6FC5398-1BP10-2BA0
5.7 Contour accuracy, CPRECON, CPRECOF
Activate programmable contour accuracy
Deactivate programmable contour accuracy
;Activate contour accuracy
;Machine contour at 10 m/min in continuous-path mode
;Automatic feed limitation in circular block
;Feed without limitation to 10 m/min
Path Action
223