曲面交线族的包络及环面蜗杆节面螺旋线

Envelope of Cross lines and Spiral Line on Pitch Surface of Envelope Worm

提出曲面交线族的包络求法及其在平面二次包络环面蜗杆中的应用，可以方便地求出蜗杆节面螺旋线．

Envelope extraction of cross imes upon two surfaces and application in TP worm have been presented. The spiral line on pitch surface of toroidal envelope worm will be easy obtaineo.