Next generation NC machining system based on NC feature unit and real-time tool-path generation

摘要

In order to improve the control and information integration capability of an NC machining system, this paper provides a new concept - an NC feature unit (NCFU), which is a feature-based and a basic control unit. First, as a feature-based control unit, NCFU possesses geometric form and control parameters, which are a subclass of high-level CAD/CAM features so that it can be used as an information exchange medium between NC machining systems and other manufacturing execution systems. Secondly, as a basic machining control unit, NCFU uses a geometrically defined closed and non-gouging machined area. On the one hand, through decomposition, a machined object can be divided into a combination of several NCFUs. On the other hand, since NCFUs are non-gouging, the algorithm for NCFU-based tool-path generation is simple enough to be executable in real-time. This paper discusses NCFU-based applications in 2 1/2 -D profile/pocket and 3D surface mill machining, including the NCFU definition and the related algorithms for decomposition calculation and area interpolation. A next generation NC machining system based on NCFU, including an NCFU-based NCP and an NCFU-based CNC system, has been prototyped by China's State 863/CIMS Design Automation Laboratory in Beijing University of Aeronautics and Astronautics. An NCFU is being used as the information exchange medium in an internet-integrated manufacturing system with NC machining at Hong Kong Polytechnic University.