A Line and Arc Transition Tool Radius Compensation Algorithm for Convex Contour

Tool radius compensation is necessary to CNC machining. However, B tool radius compensation leads to work piece burning at the sharp corner of convex contour because of the long time contacts between the work piece and tool, and C tool radius compensation frequently changes machining feed rate for its broken line tool path. This paper presents a novel tool radius compensation method suitable for high speed machining of convex contour, which have the advantages of both B and C tool radius compensation. It uses compound transition with line and arc between the adjacent blocks of CNC program. The offset tool paths of the adjacent blocks extend a small line segment respectively along their tangent direction, then insert an arc between the end points of the two extended line segments. The results of simulation and experiments show that the machining quality of the sharp corner of convex contour is improved and the machining time is shorter than C tool radius compensation.