Development of CAM system for 3D surface machining with CNC lathe

We have developed a new machining method which realizes turning of non-axisymmetric curved surfaces with a rotation axis (called NACS-Turning hereafter). NACS-Turning is a CNC turning method with 3-axis synchronous which is composed of a turning axis and two translation axes. This method forms a profile of a non-axisymmetric curved surface by adopting a liner motor in X axis and by synchronizing the X axis with the rotation axis at high speed. We confirmed dramatic improvement of productivity by using this machining method. However, at present, the generation of tool paths for shape forming using NACS-Turning are obtained with APIs associated with a commercial 3D-CAD program and geometric calculations. Therefore, we have developed a new CAM application for NACS-Turning in this paper. Since this machining method is three-axis simultaneous control, even though composition of the axis is the same as a general two-axis turning lathe, tool paths have to be generated in three dimensional space. Therefore, applying for a tool generation method of a machining center is required. Specifically, machining points are generated by calculating intersection lines on free surfaces as machining surfaces are calculated, and coordinates of tool center points are calculated by using the inverse offset method. In this paper, first, outline of NACS-Turning is mentioned. Next, the detail of the developed CAM system which is limited to a rotary tool. Finally, we report effectiveness by cutting experimentation.