A Simulation And Verification Of Experiment Study Of The Surface Roughness For The External Surface Of Pipe With Translational CNC Milling

Nuclear energy plays an important role in China’s economic development and governments of different countries attach great importance to the development of safety nuclear power. In nuclear power pipeline of AP1000, the main nuclear pipe connects pressure vessel of nuclear reactor with steam generator, its surface machining quality plays a key role in the safety of nuclear power. Surface roughness is the most direct evaluation of the surface quality of the main nuclear pipe.A simulation surface roughness model in the translational CNC milling system for the external surface of pipe is built using point by point comparing arc interpolation method, and analyses the external surface roughness of milled workpiece. Using point by point comparing arc interpolation method can easily generate highly approximate tool path. Using a Z-map method to discrete the milling area of the workpiece can reduce the computational expense. There is a high consistent between point by point comparing arc interpolation method and the translational CNC milling system for the external surface of pipe. The modeling algorithm proposed in this paper is simplicity, high precision, low calculation and easy to be programmed.Using point by point comparing arc interpolation method and Z-MAP method, surface to pography after processing is generated by tracking the relative position between cutter tool and workpiece. The least squares method is used to calculate the surface roughness Ra (range 0.6170-1.275 microns)along the diameter direction and the generating line direction. We also explore the influence of feeding speed, cutting angle, intermittent feeding mode and spindle speed on the surface quality of nuclear main pipe, using Ra as a measure of the surface qualityTo verify the modeling method, we create a processing model of representative area of the outside surface of main nuclear pipe, using UG virtual processing software. The cutter paths are generated, according to the characteristics of intermittent feeding mode. UG processing codes are generated through virtual machining. A experimental milling then can be carried out by entering the UG processing code in ball end milling of three axis NC machine. Surface roughness of the processing area can be measured by using a Zygo measuring instrument. We compare the simulation result with the measured one. And we find that the relative measurement error is between6.51% and 14.55%, thus the validity of the proposed modeling method has been verified. The simulation method has been applied in the three axis NC milling machining of outside surface of main nuclear pipe.