CL Output for Circular Interpolation
You can specify circular interpolation for tool motion in Creo NC by using the parameter CIRC_INTERPOLATION. If POINTS_&_ARC or ARC_ONLY is specified, the CL file will contain the following lines for each arc or circle encountered:
GOTO / x, y, z
CIRCLE / x, y, z, i, j, k, r
GOTO / x, y, z
x, y, z
x, y, z
..
..
..
x, y, z
The GOTO statement preceding the CIRCLE command specifies the start point of the arc. The following GOTO statements specify the points on the arc, the last line specifying the arc end point. For POINTS_&_ARC, the number of points output is controlled by the tolerance (the smaller the tolerance, the greater the number of points). For ARC_ONLY, a minimum number of points, determined by the NUMBER_OF_ARC_PTS parameter value, is output.
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The GOTO statements have the format shown above if the tool axis is parallel to the Z-Axis of the Machine coordinate system; otherwise, the tool axis vector will also be output.
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The CIRCLE command specifies circular interpolated tool movement, where:
x, y, z—Coordinates of the center.
i, j, k—Plane vector.
r—Radius.
\ i\ \ \ j\ \ k\ \ \ Plane\ Direction
The plane vector determines the plane and direction using the "right hand rule":
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i
|
j
|
k
|
Plane
|
Direction
|
|---|---|---|---|---|
|
0
|
0
|
1
|
XY
|
CCW
|
|
0
|
0
|
–1
|
XY
|
CW
|
|
0
|
1
|
0
|
XY
|
CCW
|
|
0
|
—1
|
0
|
XY
|
CW
|
|
1
|
0
|
0
|
XY
|
CCW
|
|
—1
|
0
|
0
|
XY
|
CW
|
APT Format
If CIRC_INTERPOLATION is set to APT_FORMAT, the CL output for each arc or circle encountered will be in the auxiliary format:
INDIRV / i, j, kTLON
GOFWD / (CIRCLE / x, y, z, r), ON, (LINE / x1, y1, z1, x2, y2, z2)
where:
i, j, k—The unit vector.
x, y, z—Coordinates of the circle center.
r—Circle radius.
x1, y1, z1 and x2, y2, z2—Coordinates of the two points defining the exit line.
Helical Interpolation
Helical interpolation is provided for Thread Milling. Output format uses CIRCLE with differing Z coordinates at the start and end point. Difference in Z values is based on the thread pitch and the fraction of the distance travelled around the helix. For the CIRCLE statement, Z dimension used is the same as the initial point. Sample output is shown below:
...
FEDRAT / 12.000000, IPM
GOTO / 8.198000, 0.000000, -0.625000
FEDRAT / 8.000000, IPM
CIRCLE / 8.000000, 0.000000, -0.625000, $ $$ 1ST ORBIT
0.000000, 0.000000, 1.000000, 0.198000
GOTO / 8.198000, 0.000000, -0.583333
CIRCLE / 8.000000, 0.000000, -0.583333, $ $$ 2ND ORBIT
0.000000, 0.000000, 1.000000, 0.198000
GOTO / 8.198000, 0.000000, -0.541667
FEDRAT / 12.000000, IPM
...