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Chapter 3 G Commands
101
Ⅰ
Programming
Original coordinate system
New coordinate system
G54 coordinate system
A
Original coordinate system
New coordinate system
G55 coordinate system
A
ZOFS1
ZOFS2
All workpiece coordinate
systems offset vector A in
the figure
3.21 Fixed Cycle Command
To simplify programming, the system defines G command of single machining cycle with one
block to complete the rapid traverse to position, linear/thread cutting and rapid traverse to return to
the starting point:
G90: axial cutting cycle;
G92: thread cutting cycle;
G94: radial cutting cycle;
G92 will be introduced in section Thread Function.
3.21.1 Axial Cutting Cycle G90
Command format:
G90 X(U) __ Z(W) __ F__; (cylinder cutting)
G90 X(U) __ Z(W) __ R__ F__; (taper cutting)
Command function:
From starting point,
the cutting cycle of cylindrical surface or taper surface
is completed by radial feeding(X) and axial (Z or X and Z) cutting.
Command specifications:
G90 is modal;
Starting point of cutting: starting position of linear interpolation (cutting feed)
End point of cutting: end position of linear interpolation (cutting feed)
X: X absolute coordinates of cutting end point
U: Different value of X absolute coordinate between end point and starting point of cutting
Z: Different value of Z absolute coordinate between end point and starting point of cutting
W: Different value of Z absolute coordinate between end point and starting point of cutting
R: Different value (radius value) of X absolute coordinates between end point and start point of
cutting. When the signs of R is not the same that of U, R
│≤│
U/2
│
; when R
＝
0 or the input is
default, the cylinder cutting is executed as Fig.3-17, otherwise, the cone cutting is executed
as Fig. 3-18; unit: mm.
Ranges of X, U, Z, W
，
R are referred to Table 1-2 of Section 1.4.1, unit: mm/inch.
Cycle process:
①
X rapidly traverses from starting point to cutting starting point;
②
Cutting feed (linear interpolation) from the cutting starting point to cutting end point;
③
X executes the tool retraction at feedrate (opposite direction to the above-mentioned
①
), and
return to the position which the absolute coordinates and the starting point are the same;
④
Z rapidly traverses to return to the starting point and the cycle is completed.
