FEM Simulation And Deformation Prediction Of End Milling Machnining Process Of Aeronautical Frame Monolithic Components

Machining efficiency and quality is the core of advanced mechanical processingstudy. In the aviation and aerospace manufacturing industry, in order to reduce theweight and enhance the strength and mobility of the aircraft and spacecraft, we needto adopt typical thin-wall key parts such as the integral panel used in aircraft, integralwing rib and the turbine blade of engine and so on, which possess the generalcharacteristics of large dimensions, complex contours, low stiffness, high demands ofsurface precision. NC milling procedure is taken in the machining process.Nevertheless, low efficiency is obviously in the course of milling, and thedeformation mechanism of thin-wall structure parts is still not clear yet, theprocessing sequences are determined merely by experiences, we are not able tooptimize the parameters which based on the prediction of parts deformation.Furthermore, the parts deformation induced by functions of low stiffness, residualstress, large cutting force, clamping force doesn’t make the realistic cuttingparameters amount to the nominal values, which will increase the magnitude ofprocessing error and reduce the machining accuracy and surface quality, even lead tothe unnecessary scrapping. Thus, by using the FEM numerical simulation technique, astudy is carried out to the milling process of thin-wall parts of aircraft aluminum7075-T7451.The process of the simulation study is: analyze the mechanism of cutting process,establish the finite element model of rigid three-dimensional oblique cutting toolâ†'establish the finite element model of three-dimensional oblique cutting carbide toolsthrough experimental verificationâ†'establish milling model legislation, analyzingaluminum siding processed into frames and other partsâ†'Analyze the influences ofthe upper material layer on the lower one in end milling processing.Through the finite element simulation study on the milling process of air thinpieces of aluminum alloy7075-T7451, this thesis makes the main contributions asfollows:The cutting force model of rigid three-dimensional oblique cutting tool. On thepremise that the tool is viewed as a rigid body, we consider the performanceparameters of the work piece material, and establish a three-dimensional finite element model of cutting force with micro-bevel cutting edge, and carry out acutting force test for the whole milling process in particular. The results showthat the proposed cutting force finite element simulation method enjoys a highlevel of accuracy (error extent is less than9%), at the same time, provides thetheoretical basis and convenient methods for the optimization of cuttingparameters.The cutting force model of three-dimensional oblique cutting using carbide cuttingtools. Based on the study of the aforesaid rigid three-dimensional oblique cuttingtool. We consider to use the carbide cutting tool, establish a more completedfinite element model of three-dimensional oblique cutting force using microcutting edge, revealing the distribution rules of cutting force and stress whichprovide the reliable theory basis for the purpose of effectively protecting the tool. End milling model. When milling tool is regarded as a rigid body, it simulatedthe processing procedure of panel set into a whole box of parts, access to theprocessing of deformation, cutting force, stress, surface residual stress anddistribution of materials processing the upper middle and lower impact ofmaterials processing.The study of material impact. Based on the above studies of end milling process,the legislation and semi-milling box full box set milling model are established.The influence of upper layer material on the lower layer material in themachining process is studied. When milling the material of same thickness, weneed to consider the fact that lower layer material would impose a chip breakingforce on the upper layer material, furthermore, milling the upper material wouldcause the rising temperature and making the material soft, which would increasethe milling force of the upper layer material, reduce the milling force whenmilling the lower layer material, milling force of the upper material> millingforce of a half box> the milling force of the lower material.The optimization of cutting parameters. Aiming at machining deformation of airthin-wall integral structure part, we set up a optimizing model on the basis ofminimum clamping sequence obtained from the maximal machining distortion,to implement the synchronous optimizing design in terms of cutting thickness,feeding speed, cutting path, machining sequences, the magnitude of clampingforce, application point, as well as the clamping sequences. This paper is an applied basic research, which is common and has potentialapplied value in the numerical simulation. In the aerospace manufacturing industry,this research will develop technology based on scientific calculation procedures,which has special instructive meaning to the overall structure of thin air, and otherrelated fields of processing. It optimizes milling parameters and improves machiningefficiency, and technological level of manufacturing. It lowers production costs,improves part surface quality and machining precision, which has scientificsignificance and practical engineering value. This simulation of the cutting processprovides theoretical basis for forming a meaningful principle for today’s aerospaceindustry and pursuing high precision, high efficiency and high reliability.