【作者】 魏延军；

【导师】 郭晓光；

【作者基本信息】 大连理工大学 ， 机械制造及自动化， 2013， 硕士

【摘要】 超精密切削技术在国防和民用工业中均起着重要作用,对超精密切削机理的研究一直是制造领域重要的研究方向。目前对超精密切削机理的研究主要由实验和数值模拟两种方法。切削实验作为研究超精密切削机理的重要途径,可以为实际加工制造提供最直接的依据,但是它也存在一定局限如需要精密的实验设备且费时费力。随着计算机技术的发展,模拟仿真技术已逐渐成为研究切削机理的重要手段,其中以有限元法(FEM)最为典型。但是当处理大变形问题时,有限元经常会遇到网格畸变等问题,因此本文引入了一种新的无网格法——SPH法(Smooth Particle Hydrodynamics)对超精密切削过程进行仿真。本文从以下方面进行了相关研究：1.简要介绍了数值仿真方法在切削过程研究中的发展历程及现状,探讨了传统有限元法的应用及局限。阐述了SPH法的发展及基本原理,介绍了SPH法目前在金属切削仿真方面的应用现状,对SPH与FEM的优缺点进行了对比。2.详细论述了建立超精密切削仿真模型的过程：使用ANSYS建立模型有限元部分,设定单元类型、材料模型、边界条件、输出设置等,进一步使用LS-PREPOST建立模型SPH部分,设置接触方式以及FEM-SPH耦合。3.针对AISI4340钢的超精密切削过程建立FEM-SPH耦合模型,对切削过程进行并进行结果分析。探讨了超精密切削过程中等效应力、等效应变分布情况,分析了切削力、切削温度变化规律以及加工表面残余应力的分布情况,并与实验结果进行了对比。此外还分析了金刚石刀具钝圆半径对材料去除机理的影响,对刀具负前角的形成过程以及影响进行了讨论。4.针对K9光学玻璃超精密切削过程进行了仿真。探讨了K9玻璃在超精密切削过程中脆性裂纹的产生及扩展机理,重点分析了K9玻璃脆性与塑性去除两种模式,通过对不同切削深度下切削过程的仿真,获得脆塑转变临界深度,对两种去除模式下的加工表面质量以及切削力进行了对比。此外还分析了金刚石刀具前角对脆性裂纹产生、扩展的影响。更多还原

【Abstract】 The ultra-precision cutting technology is widely used both in the field of national defense and civil industry, so the ultra-precision cutting mechanism is always an important research issue. There are mainly two methods used in ultra-precision cutting research: experimental method and numerical simulation. As an important approach to cutting mechanism, ultra-precision cutting experiments can provide first-hand data for real manufacturing, but it usually needs precise machine tools and is very expensive and time-consuming.With the development of computer technology, numerical simulation has gradually becomes an important method for ultra-precision cutting mechanism and the symbolic is the finite element method (FEM). However, FEM often confronts the mesh distortion problem when dealing with large deformation problems in processes, such as the cutting process. So a new mesh-free numerical method——SPH (Smooth Particle Hydrodynamics) is introduced here to simulate ultra-precision cutting process. The main contents of this thesis are as follows:1. The development and application of numerical simulation methods in cutting research are briefly presented and the main drawbacks of FEM are discussed. The history and basic principles of SPH are given and the comparison between FEM and SPH is made.2. The whole process of building the ultra-precision cutting model is given in details. First the FEM part of the model is created using ANSYS and element type, material model, boundary conditions etc. are set. Then the SPH part of the model is created using LS-PREPOST and the contact type and FEM-SPH coupling are also set.3. A FEM-SPH coupling cutting model for AISI4340steel is given and simulation results are analyzed. The effective stress and strain distribution are discussed and the variation principles of cutting force and temperature field are analyzed. The residual stress distribution on the formed surface is described. The results are verified by experimental results. Besides the effect of cutting tool radius on cutting process is also discussed and the formation of negative rake angle is given.4. Ultra-precision cutting of K9optical glass is simulated and analyzed. The initiation and development of cracks in glass during cutting is investigated. Especially the two cutting modes:brittle mode and plastic mode are discussed and the critical cutting depth is given by performing the simulation under several different cutting depths. Cutting force and formed surface quality are also given. Furthermore the effect of rake angle on initiation of cracks is studied as well.更多还原