车削图示 M30x2-6g 的普通螺纹
由GBl97—81知该螺纹大径为Φ30 mm 所以编程大径取为Φ29. 7mm，设牙底由单一圆弧形状构成，取圆弧半径为R =1/8H =0.2.则编程小径为
d’=30-7/4×0.866×2+2×0.2-0.038-0.17/2=27.246取编程小径为Φ27.3mm
加工程序如下
%0005
N01 G92 X270.0 Z260.0
N02 M03 S800
T0101
N03 G00 X35.0 Z104.0
G00 G90 X28.9
N04 G32 G91 Z-53.0 F2.0
G00 G91 X100.0
G00 Z53.0
G00 G90 X28.2
N05 G32 G91 Z-53.0 F2.0
G00 G91 X100.0
G00 Z53.0
G00 G90 X27.7
N06 G32 G91 Z-53.0 F2.0
G00 G91 X100.0
G00 Z53.0
G00 G90 X27.3
N07 G32 G91 Z-53.0 F2.0
G00 G91 X100.0
G00 Z53.0
T0000
N08 G00 X270.0 Z260.0
N09 M05
N10 M30
