Computer-Aided Geometry Design of Trapezoidal Threaded Variable Pitch Conical Lead Screws

Based on conical screw matrix transformation, equations of variable pitch conical helix and helicoid are derived. The surface geometry of a trapezoidal threaded variable pitch conical lead screw is generated by a trapezoid with a variable pitch conical screw motion. A computer-aided design code is developed with Patran Plus solid modeling. The result of this work is necessary for the computer-aided machining of trapezoidal threaded variable pitch conical lead screws.