变截面螺旋曲面的解析几何建模与CAD绘图

扫描变换法和路径拉伸法通常用于螺旋弹簧的近似造型,通过分析比较,指出了两种方法的不足之处.运用解析几何方法,研究了圆截面螺旋曲面的建模方法,并建立了各种截面形状的螺旋曲面通用解析表达式.同时,进一步研究了变截面螺旋曲面的形成与建模方法,并在AutoCAD中给出了基于VisualLISP的各种截面形状螺旋面的CAD绘图技巧.结果表明,此建模方法能大大提高螺旋曲面造型的精确度.

The analytic geometry modeling and CAD drafting of nonprismatic helical curved surface

the scanning transformation approach and the path stretching approach are usually used for the approximation modeling of helical springs. By means of analytical comparison, the deficiency of these two kinds of method has been pointed out. The modeling method of circular sectioned helical curved surface was studied by the use of analytic geometry method, and the general purpose ana- lytical expressions for helical curved surfaces of all kinds of sectional shapes were established. At the same time, the formation and modeling methods of the variable sectioned helical curved surface were further studied, and the CAD drafting skill of a variety of sectional shaped helical surface based on Visual LISP was presented in side AutoCAD. The result indicated that this modeling method could improve greatly the accuracy for the modeling of helical curved surfaces.