大型薄壁件加工变形预测及其影响因素研究

发布时间：2018-04-29 22:12

本文选题：大型薄壁件 + 加工变形　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：大型薄壁结构零件具有结构紧凑、节省材料、重量较轻等优良特性,能够有效减轻整体结构的质量,近年来越来越广泛地应用于航空航天领域。然而,薄壁结构零件由于壁薄、刚度较低等特点,在加工过程中受到初始残余应力、切削力、装夹条件等因素的作用极易产生加工变形,严重影响薄壁零件的尺寸精度与使用性能。因此,针对大型薄壁结构零件的加工变形进行合理的分析预测,研究影响加工变形的主要因素,为制定适当的变形控制措施提供参考,具有重要的理论价值和实际意义。本文首先基于金属切削加工数值模拟技术,运用ABAQUS软件建立了铝合金材料的热力耦合二维正交切削模型和三维铣削加工模型,通过有限元仿真得到了不同切削参数下切削力和切削热的变化规律,分析了三向铣削力以及铣削加工应力场、应变场的情况。然后建立了薄壁筒形件毛坯固溶淬火过程的有限元模型,仿真得到了热处理过程中温度场与热应力场的分布规律,从而获得了分析加工变形的初始残余应力场。接着在初始残余应力、切削力、装夹条件的耦合作用下,运用ABAQUS软件自带的单元生死技术模拟材料去除,通过Fortran语言编写子程序控制载荷的施加,得到了薄壁件局部加工完成后的残余应力分布及加工变形情况。最后针对所设计的专用工装夹具方案,通过有限元仿真得到了不同涨紧块数量下的薄壁件加工变形,结果证明12个涨紧块的夹具布局最合理;同时研究了不同切削参数对加工变形的影响规律,为优选切削参数提供了依据。
[Abstract]:Large thin-walled structural parts have the advantages of compact structure, saving materials and light weight, which can effectively reduce the quality of the whole structure. In recent years, they are more and more widely used in the field of aerospace. However, due to the characteristics of thin wall and low stiffness, thin-walled structural parts are easily deformed due to the effects of initial residual stress, cutting force, clamping conditions, etc. The dimensional accuracy and performance of thin-walled parts are seriously affected. Therefore, it is of great theoretical value and practical significance to analyze and predict the machining deformation of large thin-walled structural parts, to study the main factors that affect the machining deformation, and to provide a reference for the formulation of appropriate deformation control measures. In this paper, based on the numerical simulation technology of metal cutting, the thermo-mechanical coupling two dimensional orthogonal cutting model and three dimensional milling model of aluminum alloy are established by using ABAQUS software. The variation law of cutting force and cutting heat under different cutting parameters is obtained by finite element simulation. The three direction milling force and the stress field and strain field in milling are analyzed. Then the finite element model of the solid solution quenching process of thin wall cylindrical blank is established. The distribution of temperature field and thermal stress field during heat treatment is obtained by simulation, and the initial residual stress field of processing deformation is obtained. Then under the coupling of initial residual stress, cutting force and clamping condition, the unit life and death simulation material is removed by using the unit life and death technique brought in by ABAQUS software, and the application of load is controlled by subprogram written by Fortran language. The distribution of residual stress and the deformation of thin-walled parts after local machining are obtained. Finally, according to the designed special fixture scheme, the machining deformation of thin-walled parts with different number of tensioning blocks is obtained by finite element simulation. The results show that the fixture layout of 12 tightening blocks is the most reasonable. At the same time, the influence of different cutting parameters on machining deformation is studied, which provides the basis for selecting cutting parameters.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG501;TG162

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