Geometric Design and Machining of Variable Pitch Lead Screws with Cylindrical Meshing Elements

This paper derives the surface geometry and machine tool settings for a double threaded variable pitch lead screw with four cylindrical meshing elements. A 4-axis machining center with a rotary milling head attachment is adopted for the manufacturing of the profiles of the screws. And, based on the developed surface equations and the required settings, the authors develop a computer program for solid modeling to simulate the surface geometry of such a mechanism before and after machining. The result of this work is necessary for the task of computer-aided design and manufacturing of the variable pitch lead screw transmission mechanisms for industrial applications, e.g., in shuttleless weaving looms.