
3.INTERPOLATION FUNCTION PROGRAMMING B-63944EN-2/02
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3.2 THREADING (G33)
Straight threads with a constant lead can be cut. The position coder
mounted on the spindle reads the spindle speed in real-time. The read
spindle speed is converted to the feedrate per minute to feed the tool.
Format
G33IP_ F_ ;
F :Long axis direction lead
Z
X
Workpiece
Explanation
In general, threading is repeated along the same tool path in rough
cutting through finish cutting for a screw. Since threading starts
when the position coder mounted on the spindle outputs a 1-turn
signal, threading is started at a fixed point and the tool path on the
workpiece is unchanged for repeated threading. Note that the spindle
speed must remain constant from rough cutting through finish cutting.
If not, incorrect thread lead will occur.
In general, the lag of the servo system, etc. will produce somewhat
incorrect leads at the starting and ending points of a thread cut. To
compensate for this, a threading length somewhat longer than required
should be specified.
Table 3.2 (a) lists the ranges for specifying the thread lead.
Table 3.2 (a) Ranges of lead sizes that can be specified
Least
command
increment
Command value range of the lead
0.001 mm F1 to F50000 (0.01 to 500.00mm)
Metric input
0.0001 mm F1 to F50000 (0.01 to 500.00mm)
0.0001 inch F1 to F99999 (0.0001 to 9.9999inch)
Inch input
0.00001 inch F1 to F99999 (0.0001 to 9.9999inch)