Program Integration Of Machining Error Prediction And Compensation Of Low-rigidity Workpieces

The force-induced deformation errors play an important role in machining work-pieces with low rigidity(such as thin-wall shells or narrow-section beams).Many times of cutting are always needed to ensure machining accuracy, which has a serious impact on production efficiency. The out-line machining error prediction and compensation of low-rigidity workpieces are studied in this paper. With the result of math modeling and simulation, the parameterization analysis of finite element method is realized by using some commercial software. Program integration of finite element analysis and NC code generation are developed. According to the predicted errors, the NC code of CNC machine can be modified automatically.Firstly, a concise iterative algorithm is built for machining errors of low-rigidity workpieces to deal with coupling between deformation and cutting output. The cutting force experience model and theoretical model are studied comparatively. Especially some improvement and simplification are made on the theoretical model, which is easier to set up the program of finite elements.Then, an error prediction FEM method for low-rigidity workpieces is deduced,combining with the general flow of ANSYS. Based on the cutting force experience and theoretical models, a dynamic emulation program of deformation is developed by using ANSYS Parametric Design Language. The program with a simple and friendly interactive interface can run automatically the error iterative algorithm, cutter moving and material removing through the whole FE process of error calculation. The proposed methodology and its accuracy are validated in two milling examples of three-dimensional thin plates. The key techniques in this paper can be taken as references for other cutting styles.Finally, a program integration of the manufacturing module of UG and the finite element analysis of ANSYS is established. Base on the mirror principle, a general planning for error compensation is presented. Using UG/Open API(secondary development tool in UG) and C language, a data interface between UG and ANSYS has been designed. The boundary conditions of the CAD model in UG are amended automatically according to the nodal deformation errors predicted by ANSYS. The customized design is made in UG system. Finally the NC codes including error compensation are generated in UG CAM to remove machining errors. This workpresents a new route for the integration of out-line error prediction and compensation.