| In today's society,with the rapid development of nano-science and technology,the demand for high-precision micro-parts of many industries increased significantly,micro-miniaturization technology characterized by scale small and complex structure has the broad prospective application.While the single crystal components has been used more widely and has brought great convenience to our lives because it has the benefits of good heat,fatigue and creep performance,reducing the error of precision instruments,avoiding distortion and weakness of signal and enhancing the transmission performance.Therefore,it is necessary for us to study the micro-milling and recrystallization processing property of typical single crystal components.Firstly,the structure of single crystal is introduced.The micro-milling mechanism and recrystallization mechanism are analyzed from the aspects of the radius of tool edge,the minimum cutting thickness and the principle of micro-milling trochoid.The source of milling force and the influencing factors of the machined surface roughness are analyzed theoretically,and the formula of the surface roughness is determined.Secondly,the finite element analysis software ABAQUS is used to model the typical face-centered cubic crystal workpieces and tools,and the appropriate Hill material constitutive parameters and milling parameters are selected to simulate the milling process to investigate the influence of milling speed and milling planes on milling forces.Thirdly,three kinds of nickel-base superalloy components named single crystal DD5,Inconel 600 and K445 were selected to carry out orthogonal experiments to investigate the influence order of spindle speed,milling depth and feed rate on milling force and surface roughness,find out optimal cutting parameters combination and summarize the process characteristics.Finally,single-crystal DD98 components were selected to carry out single-factor experiment of cutting parameters and heat-treating temperature respectively.Super-depth microscope and scanning electron microscope were used to observe the recrystallization layer to investigate the effects of cutting parameters and heat treatment temperature on recrystallization,propose the methods and means of inhibiting the recrystallization,and summarize the processing performance of micro-milling and recrystallization of single crystal components.In addition,the milling temperature in the micro-milling process is closely related to tool wear and tool life,even affects the surface quality of the workpiece,so this thesis takes the single crystal DD98 as the experimental material and discuss the influence of milling parameters on milling temperature through a set of single factor experiment. |
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