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Study on Deformation Prediction Theory and Methods of the Aerospace Thin-walled Components during Precision Milling Process

Author: BaiWanJin
Tutor: KeYingLin；DongHuiYue
School: Zhejiang University
Course: Mechanical Manufacturing and Automation
Keywords: Thin-walled parts CNC milling Machining distortion Local elastic deformation Finite Element Simulation Cutting force Cutting temperature Coupled thermo Processing stability Residual stress
CLC: TG54
Type: PhD thesis
Year: 2009
Downloads: 1063
Quote: 9
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Abstract

In order to achieve weight loss and improve the specific strength of purpose, widely used in the aviation industry aviation aluminum alloy material such as thin-walled parts. From the point of view of the cutting, aerospace thin-walled parts thin wall thickness and relatively low stiffness, shape coordination requirements, poor process. Overall machining precision cutting process, the local elastic deformation of the thin-walled workpieces cutting forces, uneven distribution caused by the residual stress deformation and processing system vibration phenomena are the three outstanding issues affecting the processing quality and accuracy of the thin-walled parts. In this paper, theoretical analysis, mechanical modeling, finite element modeling and experimental validation tools, aviation thin-walled precision milling deformation prediction theory and methods of in-depth, systematic study. The research work includes the following aspects: high-speed milling of aluminum alloy 7050-T7451, based on the large deformation theory and the principle of virtual work, the establishment of a three-dimensional thermal cutting process - elastic-plastic finite element model. Analysis, finite element mesh model material constitutive model of friction between the tool - chip, chip separation standards, and heat conduction equation involves cutting simulation of key technologies. Finite element simulations using the model of the process of high-speed cutting of aluminum alloy material, analysis of the chip formation process in high-speed machining process and its morphology, the 3D milling force the changes, as well as stress, strain, cutting temperature and processing and distribution of surface residual stress. Aviation aluminum alloy 7050-T7451 weeks milling process, the milling force theoretical modeling studies predicted milling force in each case, in the case of different cutting \and milling force experiments and model validation. Subsequently, the milling temperature prediction analysis and experimental research. Structures suitable for measuring milling temperature experimental system, the empirical formula of the milling temperature model obtained by orthogonal experiments and regression analysis. Vibration of thin-walled parts milling process and its stability. Kinetic model based on the thin-walled parts milling, modal analysis using the finite element method to identify the dynamic characteristics parameters of thin-walled parts, to establish the the processing stability limit criteria, and draw the spindle speed as the abscissa, the critical cutting depth ordinate the stability limit of the map, to guide the process parameters such as spindle speed and depth of cut is selected to improve processing quality and efficiency. Finally, the overall deformation of the thin-walled parts milling and local processing of deformation. Established on the basis of the finite element simulation of the milling of thin-walled parts related key technologies suitable for the analysis of thin-walled parts overall machining deformation finite element model and analysis process, and focus on the analysis of the stress field and temperature in the process Field Distribution processed workpiece residual stress as well as the processing path and cutting load on the size of the residual stress distribution. The thin-walled parts of local processing deformation prediction for tool path pattern and cutting force of these two factors. The forecast combined milling force, the establishment of suitable research local processing of thin-walled parts deformation error the \About the tool path pattern layered symmetric pass ladder symmetry pass local processing of thin-walled parts deformation.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metal cutting and machine tools > Milling and milling machine
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