CL Output for NURBS Interpolation
You can specify NURBS interpolation for tool motion in Creo NC for 3-axis and 5-axis machining using the OUTPUT_3DNURBS parameter. If you set this parameter to YES, the CL file contains NURBS motion as shown in the following example:
1. MOVNRB / M3AXIS
MOVNRB/ON,o,k,w,n,s
2. MOVNRB/1,k1,..kk
3. MOVNRB/2,cp1...cpn
4. MOVNRB / NEXT
GOTO/xyz for p1
GOTO / xyz for P2
…
GOTO / xyz for pn
4. MOVNRB/OFF
The first statement indicates the beginning of the NURBS motion for 3-axis machining. The subsequent MOVNRB statements define the NURBS motion, where:
o—Order of the curve
k—Number of knots
w—Number of weights always set to zero
n—Number of control points
s—Length of the curve.
k1,...kk—Actual knot values as scalars. One statement can have a maximum of 24 values.
cp1,...cpn—Actual control points as x-, y-, and z-coordinates. One statement can have a maximum of 24 control points.
The MOVNRB statement preceding the GOTO statement indicates the start of the actual point-to-point output for the NURBS motion. The last MOVNRB statement indicates the end of the NURBS motion.
|
|
 A similar set of statements are used for 5-axis machining with the addition of the length between the lower and the upper NURBS. The length is based on the tool length defined in Creo NC. See the following example of a CL file. |
MOVNRB/5AXIS,LENGTH,10 \ \
MOVNRB/ON,o,k,w,n,s
MOVNRB/1,k1..kk
MOVNRB/2,lowcp1...lowcpn
MOVNRB/3,highcp1, … highcpn
MOVNRB/NEXT
GOTO/xyzijk for p1
GOTO/xyzijk for p2
...
GOTO/xyzijk for pn
MOVNRB/OFF
In this case, the initial feed rate is defined before the NURBS motion. However, it can change during the NURBS motion.
NURBS interpolation is supported in Surface Milling (3-axis and 5-axis), Finishing, Trajectory Milling, Swarf Milling, Profile Milling, Volume Milling, Roughing, Reroughing, Local Milling, Face Milling, Pocket Milling, and Corner Finishing.
|
|
The NURBS format is supported by G-Post.
|