CAD/CAM System For Marine Propeller

Marine propeller is a type of free form surface part. Its design and manufacture precision decide ship's thrust efficiency directly. The traditional manufacture method of a propeller is by roughing with general milling machine plus a mass of manual polish. It is laborious and time consuming and the precision can't be guaranteed. With the development of NC technology, at present, most of the machining of a propeller is often finished by a NC machining, but the NC machine tool factories are not provide the professional software package for marine propeller manufacture. Consequently, many marine propeller factory have to use universal CAD/CAM software packages( such as CATIA, CAMMAND, UGNX, Pro-E and so on) as design and manufacture programming platform. Because it is lack of pertinence to use universal software for marine propeller manufacture programming, it is still laborious. There are professional propeller CAD/CAM software overseas, but these software are expensive, many factories can not pay them. It is the best way to solve all problems to Designing professional software with independent intellectual property rights.In order to develop CAD/CAM software for marine propeller with independent intellectual property rights, we must digest and absorb advanced technology; on the other hand we must strengthen the research for the NC processing theory and application. According to requirement of software project and marine propeller factory, based on the research of designing method of marine propeller and characteristics of 5-axis machining, a CAD/CAM software of marine propeller has been developed by using VC++6.0 platform and three-dimensional graphics developing instrument OpenGL.The system uses fair fitting method of B-spline surface for sectional points to construct marine propeller surface model according to different type propeller's atlas, and uses OpenGL interface functions to display with three-dimensional graphics. It also can implement dynamic observation of graphics.The non-interference tool path files can be generated by using this system via choosing tools and processing schemes properly. The dynamic simulation of machining process is realized by using double buffer technology provided by OpenGL. At the end, the NC code is generated by post processing for specified machine tool.According to the requirements of module designing, the system structure is presented and the main functional modules are implemented. By using this system, the surface model of marine propeller, tool-path generation and machining simulation can be realized quickly andvisually. On the same time, the system possesses the characteristics of good stability and expansibility.