The Research On The NC Programming Technology And The Implementation Of The CAM System Based On Polar-coordinate

Polar-coordinate based NC machine tool is designed to process large-sized rotary parts and discoid parts which applied widely in aerospace, shipbuilding and construction machinery. Introduced a polar-coordinate motion system consisting of a rotary working-table and a slideway, the specialized NC tool makes it easier to locate and positioning the gear involutes, helicoids and cam faces on the tool and available a higher machining accuracy.A corresponding CAM system matching up to the new tool is in urgent need. The thesis discusses the different coordinate systems and interpolating movement methods between the Cartesian CNC system and the polar-coordinate CNC system which lead to the different functions of the CAM software respectively. By drawing lessons from the existing linear approaching methods, a Archimedes'spiral approximation algorithm for the non-circle quadratic curves, including ellipsese, hyperbola, hyperbolas and involute curves, are put forward in the paper accompanied by error estimations. Employing the idea of equidistant approach method, numerical simulation of the novel algorithm in Mathematic results a almost 40% decrease in error ratio compared with the linear approximation algorithm, meanwhile, hyperbolas is a exception. A uniform iterative formula is generalized to the handle frofile₂D and fixed contour processing.A secondary-developing program has been developed to realize the polar-coordinate CAM based on the UG/OPEN API platform. After completing the definition of the user's interactive dialogs in UIStyler, Menu Script module, a involutes preprocessor for the polar-coordinate NC tool was implemented applying the OPEN API functions. According to the system requirement analysis and description, a framework for the CAM software was established prepared for three-dimensional processing which contains a rough finishing CAVITY_MILL operation, a semi-finishing COUNTOR_AREA operation and a FLOWCUT_SINGLE operation.A tool database was discussed by adapting Access database and ODBC API interface to meet user's demand. The postprocessor for polar-coordinate the NC tool was custom-tailored in the UG POST Builder to accomplish the transformation from the CLSF files to the G-code processing file following the polar-coordinate mode.