| In contemporary society,the demand for energy is more and more big, as the main transportation of oil, gas, liquid and other tools, the application of curved pipe is more and more widely, and it determines the overall performance and security of their device. The third generation of nuclear power is associated with this article main research prototypes, it is very typical for machining after bending the elbow, and also a typical curved pipe with large length to diameter ratio.External surface of curved pipe is an open surface which can easily meet the requirements through the traditional processing technology.But inner surface of curved pipe with large length to diameter is a long and thin cavity surface,its processing is difficult and need to consider many problems in the manufacturing process such as interference of cutting tool and the workpiece, rigidity of the cutting tool, unstable cutting condition.In order to solve the above problems, putting the milling head inside the curved pipe is put forward.Based on the guide rail feed milling, our group devised a built-in guide pipe inner surface treatment device,which can effectively avoid machining interference and obtain better consistency of surface quality.This article treats the built-in processing device as the research object, through the analysis of processing principle of longitudinal feed device along the bend guide line and along the normal cross section of transverse feed and different morphology of concave and convex in the inner surface of different location, this text improved the traditional method of Z-map according to the Angle of mesh, and combined with tool inclination of five-axis machining the feeding direction angle model is improved. A kind of suitable for bending tube surface milling force modeling method is put forward and simulating calculation of the instantaneous milling force in the process of machining is completed through MATLAB.Under the same process parameter selection and simulation processing, verified experiment is made through intercepting three small curved surface in the bent tube0°,90°,180°location.The experiment of milling force is consistent with prediction of milling force in both extreme value and the change rule.The milling force extremum error is within16%, so the reliability of the milling force model is proved. The milling force model has a certain guiding significance for the curved tube surface special processing device intensity, the structural optimization and the process parameter selection of processing. Based on established milling force model, this text selects in bending tube surface Q=0°vertically feeding trajectory and P=30°circumferential considerate trajectory as representatives of the milling force to predict the milling force and then gets the distribution of the curved tube surface milling force in machining process. In considered of that the device design just made a simple analysis of the strength and rigidity of key components based on assumptions of the empirical formula.So based on the milling force model,this article uses the finite element analysis to make the force analysis for rail base of the built-in processing device and calculate that the bend model processing’s maximum deformation is0.047988mm and the most dangerous position is P=30°&Q=90°Finally, based on the simulation model of milling force, factors on the influence law of milling force is analyzed, and considering other factors in the process of machining, suggestions to choose suitable processing technology parameters is given. Above work can not only provides a theoretical basis for machining process of nuclear power main line and similar on the surface of the bent tube, but also has a good guidance for structure optimization of the built-in processing device. |
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