基于B-rep的工件表面动态几何模型

在NC（Numerical Control）仿真中，工件三维图形处理是一项关键技术。既要实现几何造型的显示功能，又要求三维图形具有可加工性、加工成品的信息具有可记录性。为此，采用B-rep（边界表示法）模型和面向对象技术相结合的方法，设计一种记录NC仿真中工件形状数据变化信息的数据结构，构建NC仿真系统中工件表面动态几何模型。实现NC仿真中每个数控刀位工件加工表面的生成与判断。NC仿真完成后，可以判断零件的加工表面与非加工表面，进而分析零件表面加工质量（表面粗糙度）。

Building Workpiece Surface Dynamic Geometry Model Basing on B-rep Model

The key technical problem of roughcast in NC machining simulation is to handle three-dimension shape,which includes the method of display and machinability of three-dimension geometrical shape of roughcast,recording the information of parts process.A kind of data structure of three-dimension shape is used to record the workpiece shape changing information which manages workpiece entity dynamic data efficiently.New workpiece machining surfaces are generated and judged ineach NC simulation step.NC simulation finished,the machining surface and the non-processed surface are analyzed and then workpiece surface roughness can be predicated.