生成螺纹线 Generate threads

螺纹线数 number of leads

改进的螺纹线 improved thread

进线口螺纹 G ; proofing grade ; category ; proofing maker

螺纹轴线 axis of thread

双线螺纹 double start thread ; thread ; double

三线螺纹 [机] triple thread ; three start thread

不正确的螺纹线 incorrect thread

三线测螺纹法 three wire measurement ; three wire method