Linking tool paths generated with different offset distances for edge quality enhancement in planar milling

Abstract

Edge quality can be effectively enhanced in planar milling by preventing the tool from exiting the work part. This is achieved by planning of tool paths offset from the part edges with appropriate distances. Two consecutive edges may require different offset distances to avoid the tool exit occurring around the joined vertex. Linking such tool paths is problematic and has not been studied. This paper presents a systematic approach to solving this problem. All geometric configurations of consecutive offset edges are recognized, simplified and classified into four groups. Corresponding algorithms consisting of three basic geometric operations (connect, trim, and extend) are developed for each group. The extra paths added in the linking process are analysed and the results show that they do not induce unfavourable end conditions such as sharp turns, overextended paths or introduction of unexpected tool exits. This work overcomes the deficiency of previous studies and completes the tool path planning for enhancement of machining edge quality.