Research On Milling Simulation Of Aviation Aluminum Alloy And Machining Deformation Of Thin-walled Frame Parts

Science and technology revitalize the country,and the aviation industry has continuously improved the requirements for parts manufacturing accuracy and product reliability.Aviation parts should not only ensure the requirements of strength and structural stability,but also pursue the principle of small quality,so thin-walled parts have been favored by aviation manufacturing industry.The shape of thin-walled parts is complex,and the overall material removal is large in the processing.Affected by cutting force and heat,friction,residual stress,processing environment and other aspects,it is prone to machining deformation,which has always plagued the precision manufacturing industry.In order to promote the development of aerospace industry,it is urgent to find ways to reduce and suppress the machining deformation of thin-walled parts.This paper mainly studies the aviation thin-walled frame parts,using simulation and experimental method to find out the laws and measures to reduce and suppress machining deformation.The detailed research contents are as follows:(1)Firstly,the whole milling process is simplified as a three-dimensional oblique cutting process of a single tooth through the cutting principle.Then,the temperature and stress distribution of the tool and the workpiece,the shape of the chip,the three-dimensional cutting force and the cutting deformation of the workpiece along different paths are obtained by using the simulation technology.Then on the basis of three-dimensional oblique cutting simulation,the vertical milling model is established,and the Python language is used to secondary develop the finite element software.Through the built-in Plug-ins module of the software,the pre-processing modeling process of the vertical milling is encapsulated into the ABAQUS kernel,so as to generate the end milling GUI modeling plug-in with simple operation,parametric modeling and graphic interaction,which greatly improves the efficiency of modeling and simulation.Finally,the orthogonal simulation experiment was carried out by using the end milling plug-in,and the milling empirical formula of hard aluminum7050-T7451 was obtained and its accuracy was verified by experiments.(2)The empirical milling force is applied to the side wall of the “?”-shaped thin-walled frame by using the obtained milling empirical formula,and the control variable method is used to study the influence of the side wall connection mode on the side wall milling deformation.Through the simulation analysis,it is concluded that when the wall thickness and material are certain,the deformation of side wall A and side wall C is positively correlated with the change of length-longitudinal ratio and length-width ratio.The deformation of side wall B is basically independent of the aspect ratio,but negatively correlated with the aspect ratio;The machining deformation is also different when the side wall connection forms are different,and the larger the milling surface is,the more obvious the deformation is.Finally,the influence of the change of the milling cutter along the feed direction and axial direction on the machining deformation of the trilateral fixed side and the free side is studied,and the influence law of the change of the milling cutter location on the machining deformation of the side is obtained.(3)Considering the initial residual stress of the part,and through simulation,it is concluded that the overall machining deformation is also different when the machining sequence is different.The optimal machining sequence is determined by comparison and verified by experiments.Finally,it is concluded that the deformation of the “I”-shaped thin-walled part is the smallest when it is processed by hierarchical and hierarchical step machining sequence,which is 43.6 % smaller than that of the unilateral machining sequence and 35.3 % smaller than that of the symmetric hierarchical machining sequence.For multi-frame thin-walled parts using “first + then ×” frame processing and oblique symmetry processing sequence can effectively reduce the processing deformation.The three-dimensional bevel cutting simulation presents the whole process of single-tooth cutting by the end mill,and can predict the stress and temperature distribution of tool-workpiece-chips during processing.The three-dimensional end milling GUI plug-in developed by Python realizes the milling of 7050-T7451 duralumin.The prediction of force and milling deformation improves the modeling efficiency.There are certain rules in the structural dimensions of the “ ? ”-shaped thin-walled frame and the processing and deformation of the side wall,which provides a basis for the study of complex and multi-frame thin-walled parts.In addition,this paper concludes that the layered and stepped milling can reduce the deformation of “I”-shaped thin-walled parts,and the milling sequence of “first +then ×” can effectively decrease the whole deformation of thin-walled multi-frame parts.The strategy has guiding value for actual machining and manufacturing.