钛合金高速铣削力试验与有限元数值分析

  本文关键词：钛合金高速铣削力试验与有限元数值分析，由笔耕文化传播整理发布。

南京航空航天大学

硕士学位论文

钛合金高速铣削力试验与有限元数值分析

姓名：易俊杰

申请学位级别：硕士

专业：航空宇航制造工程

指导教师：刘长毅

20090101

南京航空航天大学硕士学位论文

摘 要

对钛合金TC4、TC11的铣削力进行了铣削试验研究，并进行二维切削与三维铣削有限元仿真，通过仿真得出铣削力、铣削温度，与试验数据进行对比分析。

1从切削热、工件材料模型、切屑分离、摩擦类型四个方面进行切削有限元仿真，其中切屑分离是切削仿真中最重要的技术，本文以ALE、剪切失效、累进损伤失效三种技术，以不同的研究目的，分别应用于有限元切削仿真研究中。

2通过自适应和累进损伤失效技术建立了带状切屑二维切削有限元模型并进行了分析；以钛合金锯齿切屑形成机理为研究目的，利用累进损伤失效和网格重划分技术分别实现了二维锯齿切屑仿真；建立了超声振动切削钛合金二维有限元模型并进行了分析。

3建立了整体硬质合金铣刀铣削钛合金三维铣削有限元模型，对铣削有限元模型、铣削机理、铣削过程进行了分析，，进行了铣削速度、每齿进给量、轴向切深三个铣削参数对铣削力的单因素影响分析。

4 对钛合金TC4、TC11进行了三因素三水平正交铣削试验，并得到了试验铣削力结果的极差和非线性回归经验公式；为了与试验进行对比，通过减小铣刀直径、保持切削参数不变，建立了改进的三维铣削有限元模型并进行了分析。

二维切削仿真结果表明钛合金锯齿切屑的形成机理主要是热塑性失稳导致集中滑移；超声振动切削能有效的降低切削力和切削温度；三维铣削仿真结果与文献结论基本相符。铣削试验结果表明影响铣削力大小的三因素的重要性顺序为：每齿进给量、径向切深、切削速度；改进的铣削有限元仿真结果与实验数据对比，表明变化趋势是一致的。这些研究结果有利于更进一步研究钛合金的切削机理，优化加工参数。

关键词：钛合金，铣削力，有限元仿真，正交切削，三维铣削，切屑分离，网格重划分

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Abstract

The milling force of titanium alloy TC4、TC11 milling experiments were investigated; And two-dimensional cutting and three-dimensional milling finite element method (FEM) were researched and simulated, milling force、milling temperature were obtained through the simulation, compared and analyzed with experiment data.

1 Titannium cutting FEM simulation was developed from four aspects :cutting heat、workpiece material model、chip separation、friction type. ALE、shear failure、progressive damage and failure three technologies, with different research purposes, were used to the chip separation in FEM.

2 Through adaptive mesh and progressive damage and failure technology ribbon chip of 2D FEM model was established and analyzed; with research purposes of serrated chip formation mechanism of titanium alloy, using progressive damage and failure and remesh technology to achieve 2D simulation of serrated chip.

3 3D milling FEM model with solid carbide milling cutter of titanium alloy was established. FEM model of milling、milling mechanism、milling process were analyzed, single factors effect of milling force of milling speed、feed per tooth、axial depth were respectively analyzed.

4 Three factors and three levels orthogonal milling experiments of titanium alloy TC4, TC11 were run，range and non-linear regression formula of milling force experiments results were obtained. In order to compare with the experiments, by reducing the cutter diameter, cutting parameters remain unchanged; an improved 3D FEM model of milling was established and analyzed.

2D simulation results show that the titanium alloy cutting serrated chip formation mechanism: thermoplastic instability lead to concentrated slip. Ultrasonic vibration cutting can effectively reduce the cutting force and cutting temperature. 3D milling simulation results are in line with the literature. Experimental results show that the order of importance of three factors affecting milling force: feed per tooth, radial depth of cut, cutting speed. Improved milling finite element simulation results, compared with the experimental data, the trend is the same. The findings of these investigations are in favor of further study on the cutting mechanism of titanium alloy, and optimize the processing parameters.

Key Words: titanium alloy, milling force, finite element simulation, orthogonal cutting,

three-dimensional milling, chip separation，remesh

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图、表清单

图2. 1网格扫描过程中节点的再分配...............................................................................................11

图2. 2 几何特征的检测与失效..........................................................................................................11

图2. 3累进损伤退化应力应变...........................................................................................................13

图2. 4 线性损伤演化.........................................................................................................................14

图3. 1二维正交切削有限元模型.......................................................................................................18

图3. 2带状切屑的形成过程...............................................................................................................19

图3. 3 0.004s切削应力云图...............................................................................................................20

图3. 4刀具温度分布云图...................................................................................................................20

图3. 5切削力曲线..............................................................................................................................20

图3. 6刀尖与前刀面节点温度曲线图...............................................................................................21

图3. 7刀具温度云图..........................................................................................................................21

图3. 8刀尖温度曲线图.......................................................................................................................21

图3. 9切削温度云图..........................................................................................................................21

图3. 10切削应力云图.........................................................................................................................22

图3. 11切削有限元模型.....................................................................................................................23

图3. 12 第一块锯齿切屑的形成过程................................................................................................25

图3. 13第一个切屑的形成.................................................................................................................25

图3. 14锯齿切屑的形成.....................................................................................................................26

图3. 15切削力曲线图.........................................................................................................................26

图3. 16切削温度云图(v=180m/min)..................................................................................................26

图3. 17切削应力云图.........................................................................................................................27

图3. 18切削温度云图(v=450m/min)..................................................................................................27

图3. 19 切削速度v对切削的影响....................................................................................................28 图3. 20 切削厚度对切削的影响........................................................................................................29

图3. 21 摩擦系数对切削的影响........................................................................................................29

图3. 22 刀具前角对切削的影响........................................................................................................30

图3. 23 网格重划分实现切屑分离....................................................................................................30

图3. 24二维切削有限元模型.............................................................................................................31 vi

南京航空航天大学硕士学位论文

图3. 25钛合金正交切削有限元模拟结果.........................................................................................32

图3. 26锯齿状切屑的一个节块发展过程和等效塑性应变(Strain-Effective).................................33

图3. 27形成锯齿切屑时的切削力.....................................................................................................34

图3. 28发生热塑性失稳时的切屑模拟结果.....................................................................................35

图3. 29 振动切削模型........................................................................................................................37

图3. 30 刀具切入工件之前................................................................................................................37

图3. 31刀具切入工件.........................................................................................................................37

图3. 32 刀具与工件分离....................................................................................................................38

图3. 33振动切削切屑形状.................................................................................................................38 图3. 34普通切削与振动切削(摩擦系数μ=0.03)切削力................................................................39 图3. 35 普通切削与振动切削(摩擦系数μ=0.3和μ=0.03)切削温度............................................39

表3.1 TC4的化学成分.......................................................................................................................17

表3.2 TC4热导率...............................................................................................................................17

表3.3 TC4比热容...............................................................................................................................17

表3.4 TC4线膨胀系数.......................................................................................................................17

表3.5 TC4弹性模量...........................................................................................................................17

表3.6 TC4泊松比...............................................................................................................................17

表3.7 TC4 J-C模型参数.....................................................................................................................17

表3. 8 YG8刀具的物理和热力学性能..............................................................................................18

图4. 1斜角切削有限元模型...............................................................................................................42

图4. 2斜角切削仿真过程切屑应力云图...........................................................................................43

图4. 3铣削有限元模型.......................................................................................................................44

图4. 4铣削网格划分..........................................................................................................................44

图4. 5铣削仿真过程..........................................................................................................................46

图4. 6铣削温度图..............................................................................................................................47

图4. 7工件加工表面温度云图...........................................................................................................47

图4. 8刀具刀尖三节点温度曲线图...................................................................................................47

图4. 9铣削力曲线图..........................................................................................................................48 图4. 10铣削速度v对铣削力的影响(ap=5mm，ae=0.6mm，fz=0.075mm/z).................................48 图4. 11每齿进给量fz对铣削力的影响(v=300m/min,ap=5mm,ae=0.6mm)......................................49

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  本文关键词：钛合金高速铣削力试验与有限元数值分析，由笔耕文化传播整理发布。