基于轮廓搜索的机匣铣削毛坯模型自动构建方法

针对发动机机匣零件铣削毛坯模型构建中，表面凸台回转轮廓获取困难，凸台轮廓之间以及凸台轮廓与回转体轮廓之间组合难处理，毛坯构建效率低且余量分布不均的问题，提出了基于轮廓搜索的机匣铣削毛坯模型自动构建方法。用离散的方法得到复杂形状凸台特征的回转轮廓，将凸台特征与回转体特征的回转轮廓旋转投影到草图平面，结合加工余量、车削刀具尺寸等工艺信息进行毛坯轮廓搜索，进而得到余量分布均匀且符合工艺要求的铣削毛坯。该方法对机匣回转体与表面凸台进行统一轮廓搜索，并充分考虑加工工艺，能处理具有复杂表面凸台的机匣零件，效率高、通用性好；所得毛坯余量分布均匀，减小铣削材料去除量，有助于提高铣削加工效率。

Automatic Milling Blank Model Generation Method for Engine Casing Based on Contour Searching

In order to address the issue of obtaining the revolving contour of surface boss and combining the revolving contours of surface bosses with that of revolution body of the casing as well as the issue of low efficiency in generation of aero-engine case milling blank model and nonuniformity of machining allowance of the milling blank model, an automatic milling blank model generation method for casing based on contour searching is proposed. In the method, discretion is used to obtain the revolving contour of a complex-shaped surface boss. The revolving contours of the bosses are rotated to a sketch plane where they are combined with the revolving contour of the revolved body. The blank contour is searched on the sketch plane considering milling and turning machining process information. Blank model with uniform machining allowance and good manufacturability is then obtained by revolving the blank contour. The method is effective and universal in milling blank generation of aero-engine casings with various bosses on the surface. Milling efficiency is improved using the blank model generated by the method due to optimized machining allowance and minimized residual cutting volume.