A Simulation And Experimental Study On The Milling Processing Quality For Inner Surface Of Bent Pipe

The increasing demand for energy of social production provides nuclear industry a rapid development chance, and as one of the seven key nuclear island equipments, the main pipe plays a role to prevent the leakage of radioactive material, conveying pressure water containing radioactive substances and to maintain the function of the pressure boundary integrity. That sets higher technical requirement on processing quality for inner and outer surface of main pipe (surface roughness Ra3.2μm). Besides the component belongs to the pipeline structural characteristics of a large aspect ratio, with traditional machining ways, the interference between tool and workpiece as well as the lacking of stiffness of tool because of extending too long for inner surface of main pipe in existing processing program make it difficult to achieve high-quality processing result. Thus commenced its processing quality research is of great significance.Our research group has designed a milling device for inner surface of bent pipe within built-in guide previously. In this paper, the device is taken as the prototype, based on full analysis of its design and equipment processing characteristics, factors (mainly geometric factors) affecting the achievable quality of ball end milling processing for inner surface of bent pipe in this design were incorporated into modeling simulation consideration. The prediction model of inner surface processing quality is constructed for bent pipe by studying the surface texture simulation and roughness value Ra algorithm.Programming, computing and graphics plot works of simulation model were carried out with MATLAB, meanwhile the discrete points of blade, blade cutting participation in regional and minimum time step selected in this simulation algorithm have been optimized to improve computational efficiency. The reliability of model was verified through milling experiments under equal process parameters imitating feed characteristics of the device. The model can predict the results of the surface quality and texture of the inner surface of the device processing conveniently and efficiently, simulated surface morphology of microscopic geometry results are basically consistent with the measured roughness values of the relative geometry results are basically consistent with the measured roughness values of the relative error does not exceed16%. With help of this model, influences on surface processing quality of various factors were investigated subsequently, which provides some basis and reference for the research on inner surface milling quality prediction of nuclear main pipe as well similar bent pipes.