快速成形件与CAD模型间包含关系的一种通用实现方法

A versatile method of realizing containment relationships between rapid prototyping part and CAD model

为削弱台阶效应对快速成形件形状和尺寸精度的影响,提出一种实现层片尖顶偏差各种分布形式的通用方法.首先,将CAD模型在当前分层点和下一分层点的水平截面投影到同一水平面上,对其求交和求并以获取投影截面的内、外轮廓边界;其次,用过内点作旋转极径的方法将内外边界适度混合,提取当前层片的扫描轮廓.结果表明,该方法能够实现层片尖顶正偏差、负偏差和正负偏差值不等的混合偏差分布,满足不同应用目的的成形件层片尖顶的分布要求,拓展了层片尖顶混合偏差分布的内涵.

To decrease the influence of the staircase effect to the shape and dimension precision of rapid prototyping part, a versatile method of blending the adjacent section contours in CAD model is put forward by using a rotary vector. Firstly, the current and the next section in CAD model are projected onto a horizontal plane, and the outer and the inner boundary are obtained by computing the sections union and intersection. Then the adjacent contours are blended by using a rotary vector through a proper inner point in the intersection to achieve the current layer＇s scanning contour. The result shows that the method can realize the layer＇s cusp distribution of the positive tolerance, the negative tolerance, and the mixed tolerance with unequal cusp heights, meet the cusp tolerance distribution requirements of the parts applied in different situations, and expand the connotation of cusp distribution in rapid pro- totyping.