基于正交切削模拟的零件铣削加工变形预测研究

提出了基于正交切削模拟的零件铣削加工变形的预测方法,建立了三维铣削加工的有限元模型。基于正交切削加工模拟结果,利用铣削温度、铣削力的分析模型求解了三维铣削加工的瞬态温度和瞬态切削力,并将其作为动态载荷应用于三维切削加工的有限元模型,模拟了零件的三维铣削加工过程,预测了零件的变形。通过模拟结果与现场加工情况对比,证明该预测方法是行之有效的。     

航空薄壁整体结构件加工变形的有限元分析

为了研究航空薄壁整体结构件高速铣削加工中的整体加工变形,建立了基于ABAQUS/Standard有限元核心求解器的数值仿真系统,并对相关关键技术进行了研究.基于该系统研究了薄壁整体结构件铣削加工全过程,得到了加工过程中应力场、温度场的分布规律,以及加工完成后结构件的整体加工变形规律.通过模拟值与实验值对比,在误差允许范围内模拟结果是可以接受的,为薄壁整体结构件的加工变形分析提供了一种有效的方法.     

零件结构对加工变形影响的仿真与实验研究

在航空整体结构件加工中,零件结构形式影响着零件的加工变形。为提高航空整体结构件加工质量,需要优化结构,减少零件加工变形值。建立三维整体结构框类零件的有限元分析模型,利用"单元生死"技术仿真材料的去除过程。研究了零件结构形式对整体结构框类零件加工变形的影响规律,并且设计了零件结构对比切削实验,使用三维坐标测量仪测量了零件每次铣削后的加工变形,通过仿真数据与实验数据比较分析得出结论,合理的零件结构设计有助于减小零件加工变形,对于提高大型整体结构件的产品精度具有重要意义。     

基于刀具磨损的钛合金薄壁件加工变形研究

针对钛合金薄壁结构件切削加工过程中的切削力和刀具磨损进行了实验,得到了切削ZTC4钛合金的切削力和刀具磨损的经验公式。根据该薄壁结构件的实际加工情形建立了有限元分析模型,利用生死单元法、移动载荷技术和刀具磨损量线性叠加方法,模拟得到了该型薄壁件的加工变形规律,最后实际加工了一个零件,利用三坐标测量仪测量得到了零件的实际变形值,通过比对仿真值,进一步验证了有限元模型的准确性。研究结果表明,该有限元模型能够比较准确预测薄壁结构件的加工变形情况,对实际生产具有指导意义。     

航空结构件残余应力释放引起加工变形的数值模拟

航空铝合金结构件毛坯在成形过程中产生很大的残余应力,使其在后续机械加工过程中极易发生翘曲变形,采用有限元数值模拟技术,建立了航空铝合金板材残余应力释放引起加工变形的力学模型,分析了在7075T7351铝合金板材材料去除过程中残余应力释放引起的加工变形规律,并针对7075T7351隔框零件进行铣削加工变形实验研究,并与有限元模拟结果进行比较,验证了数值模拟结果具有较高的精确度。     

残余应力重分布引起的结构件铣削变形研究

航空铝合金结构件毛坯在成形过程中产生很大的残余应力,使得其在后续机械加工过程中极易发生翘曲变形,这已经成为国防武器快速开发和高效加工的瓶颈.采用有限元数值模拟技术,建立了航空铝合金板材残余应力释放引起加工变形的力学模型,分析了在7050T7451铝合金板材材料去除过程中残余应力释放引起的加工变形规律,并针对7050T7451隔框零件进行铣削加工变形实验研究,并与有限元模拟结果进行比较,验证了数值模拟结果具有较高的精确度.     

基于多应力耦合的航空框类零件加工变形仿真分析及其控制技术

针对航空铝合金7050-T7451材料框类零件数控加工变形问题,采用三维有限元方法分析了耦合应力对加工变形的影响机理。首先,利用单元生死技术、动态载荷步分别模拟铣削加工过程中材料去除和走刀过程,分析了初始残余应力、装夹应力和铣削机械应力耦合状态下走刀路径对加工变形大小及其分布状况的影响规律。其次,以不同的装夹方案为边界条件,分析了耦合应力对加工变形的影响规律,可为航空结构件加工的尺寸稳定性提供理论指导和工艺策略。     

薄壁件铣削加工中的铣削力仿真分析

为了研究薄壁件铣削加工过程中的铣削力分布规律,在对铣削加工模型分析基础上,针对材料为45#钢的薄壁零件,采用商业有限元软件ABAQUS建立能够反映实际状态的三维铣削模型,并进行模拟,获得铣削力曲线和应力、应变分布情况。为验证仿真结果的可行性,采用与有限元模型相同的条件进行实验并获得铣削力实验数据,对比表明:铣削力的模拟结果与实验结果能够较好的吻合。分析结果表明:所建立的薄壁零件三维铣削有限元模型是可行的,其对铣削力和薄壁零件加工变形预测具有重要意义。     

2A12铝合金机油泵盖的铣削变形分析及控制策略

针对薄壁零件铣削加工中的变形问题,基于UG、Hypermesh和ABAQUS软件,建立了2A12铝合金机油泵盖的有限元分析模型,进行了铣削变形有限元模拟和研究,获得了机油泵盖变形的基本规律。针对机油泵盖变形过大问题,对夹具进行了改进,改进后的模拟结果表明效果良好。进行实际加工实验,实验结果表明:有限元模拟得出的变形量趋势及位置和实测的大致上吻合,可以认为铣削力经验模型及铣削变形有限元模拟可靠,为进一步研究控制薄壁件加工变形方案提供了依据。     

基于响应面法的薄壁件铣削参数有限元优化

铝镁合金薄壁结构件在航空工业中广泛应用,但在其加工过程中常因为刚度不足而引起变形。针对上述问题,提出一种基于响应面法的铣削加工参数有限元仿真方法,可有效控制变形及加工质量。对圆柱螺旋立铣刀的铣削加工过程建立刀具平均切削力模型,并将该模型应用于有限元仿真试验。通过对Box-Behnken法设计的四因素三水平试验结果进行分析,探讨了切削速度、切削深度、切削宽度和每齿进给量等4个因素与切削变形的关系。同时,以工程中的典型薄壁结构件为例,优化了该类薄壁结构件的铣削参数,经有限元仿真验证,该优化方法能够有效控制铣削过程的变形。     

Multi-objective process optimization for micro-end milling of Ti-6Al-4V titanium alloy

Micro-end milling is one of the promising methods for rapid fabrication of features with 3D complex shapes. However, controlling the micro-end milling process to obtain the desired results is much harder compared to that of macro-end milling due to the size effect and uncontrollable factors. The problem is much pronounced when workpiece material is a difficult-to-process material such as titanium-based alloys which are widely used as material of choice for aircraft structures, turbine blades, and medical implants. In order to find the optimal process parameters which minimize the surface roughness and burr formation, experiments were conducted and models obtained with statistically based methods utilized in multi-objective particle swarm optimization to identify optimum process parameters. The results show that the average surface roughness can be minimized while burr formation is reduced concurrently.     

Comparison and analysis of main effect elements of machining distortion for aluminum alloy and titanium alloy aircraft monolithic component

Main effect elements of machining distortion for aluminum alloy and titanium alloy aircraft monolithic component are investigated by finite element simulation and experiment. Based on an analysis of milling process characters, finite element models of machining distortion are developed. Considering the action of initial residual stress, finite element simulation and analysis of machining distortion for aluminum alloy aircraft monolithic component are performed. Initial residual stress, cutting loads, and coupling action of these two effect factors are taken into account, respectively, to perform finite element simulations of machining distortion for titanium alloy aircraft monolithic component. The finite element simulation results are compared with experiment results and found to be in good agreement, indicating the validation of the proposed finite element models. The research results show that the initial residual stress in the blank is the main effect element of machining distortion for aluminum alloy aircraft monolithic component, while cutting loads (including cutting force and temperature) are the main effect element of machining distortion for titanium alloy aircraft monolithic component. To decrease machining distortion of aluminum alloy aircraft monolithic component, the initial residual stress in the blank must be controlled first. Similarly, to decrease machining distortion of titanium alloy aircraft monolithic component, the cutting loads must be controlled first.     

实时振动数据驱动的薄壁件平铣工艺参数自适应优化

为减小加工振动对薄壁件平铣（端面盘铣）加工质量及效率的影响,提出一种实时铣削振动数据驱动的平铣工艺参数自适应优化方法。首先根据再生效应原理建立薄壁件平铣颤振稳定性模型。其次将薄壁件平铣过程中前一个工步内的实测振动数据分为若干段,以此模拟其材料去除过程,对各段铣削振动数据进行分析,由有限元单位力法和优化STD法分别识别出薄壁件刚度和各材料去除阶段模态频率及阻尼比,并由此导出薄壁件单模态频响函数,将其代入颤振稳定性模型求解稳定域叶瓣图并做插值处理后即可确定包含材料去除信息的薄壁件三维颤振稳定域叶瓣图。基于此,以避免铣削颤振、共振和满足机床性能要求为约束条件,以材料去除率最大为目标,利用遗传算法计算薄壁件下一个工步较优的工艺参数,如此循环进行,直到完成薄壁件加工。最后,通过某型飞机垂尾薄壁装配界面平铣试验验证该方法的可行性和有效性。由试验结果可看出,采用优化后的加工工艺参数,能使薄壁装配界面粗加工过程表面粗糙度从Ra 3.2提升为Ra 1.6,加工效率提高33%。     

Milling Force Model for Aviation Aluminum Alloy:Academic Insight and Perspective Analysis

Aluminum alloy is the main structural material of aircraft,launch vehicle,spaceship,and space station and is pro-cessed by milling.However,tool wear and vibration are the bottlenecks in the milling process of aviation aluminum alloy.The machining accuracy and surface quality of aluminum alloy milling depend on the cutting parameters,material mechanical properties,machine tools,and other parameters.In particular,milling force is the crucial factor to determine material removal and workpiece surface integrity.However,establishing the prediction model of milling force is important and difficult because milling force is the result of multiparameter coupling of process system.The research progress of cutting force model is reviewed from three modeling methods:empirical model,finite element simulation,and instantaneous milling force model.The problems of cutting force modeling are also determined.In view of these problems,the future work direction is proposed in the following four aspects:(1)high-speed milling is adopted for the thin-walled structure of large aviation with large cutting depth,which easily produces high residual stress.The residual stress should be analyzed under this particular condition.(2)Multiple factors(e.g.,eccentric swing milling parameters,lubrication conditions,tools,tool and workpiece deformation,and size effect)should be consid-ered comprehensively when modeling instantaneous milling forces,especially for micro milling and complex surface machining.(3)The database of milling force model,including the corresponding workpiece materials,working condi-tion,cutting tools(geometric figures and coatings),and other parameters,should be established.(4)The effect of chatter on the prediction accuracy of milling force cannot be ignored in thin-walled workpiece milling.(5)The cutting force of aviation aluminum alloy milling under the condition of minimum quantity lubrication(mql)and nanofluid mql should be predicted.     

3D FEM simulation of milling process for titanium alloy Ti6Al4V

Milling is used as one of the most important tools with the complex tool geometry in industry. However, the complex milling process cannot be simulated by 2D finite element method. Therefore, a more real 3D finite element model (FEM) for the complex milling process of titanium alloy Ti6Al4V is firstly developed using the finite element software ABAQUS. This model takes into account the dynamic effects, thermomechanical coupling, material damage law, and contact criterion. Firstly, the Johnson–Cook material constitutive equation was proposed, considering the effects of strain, strain rate, and temperature on material properties. Secondly, the damage constitutive law was adopted as the chip separation criterion. Then, the simulation for the milling process of Ti6Al4V was conducted through ABAQUS based on the established 3D FEM. Finally, chip formation, stress distribution, cutting force, and milling temperature were obtained. Further, a series of milling experiments of Ti6Al4V were carried out to validate the simulation results. It confirms the capability and advantage of 3D FEM simulation in the complex milling process of titanium alloy.     

薄壁结构件铣削参数有限元正交优势分析及优化

大型整体薄壁结构件在航空、航天工业中得到了广泛应用。但由于其刚性差,在铣削加工过程中常常出现铣削力过大而引起较大的变形,严重影响工件的加工质量和精度。针对上述问题,提出一种有限元正交优势分析方法,用以优化铣削参数,减小铣削产生的零件变形。该方法采用正交试验设计规划指导有限元铣削加工变形分析的参数方案设计,通过不同方案的计算结果研究分析铣削速度、铣削深度、铣削宽度、每齿进给量对加工变形的影响,得到各铣削要素选择的较好水平;采用优势分析方法对正交试验结果进行处理,得到各铣削要素对加工变形的贡献率,从而确定优化的铣削加工方案。以某薄壁框类零件为例得到了铣削参数的优化组合,经过验证,优化后的试验方案减少了铣削产生的最大变形量,证明了该方法的可行性及有效性。     

超声波铣削加工材料去除率的理论模型

超声波铣削加工适于硬脆材料复杂型腔的加工，加工中影响材料去除率的因素很多，为了优化加工参数以及更好地控制加工过程，研究了各种加工参数对材料去除率的影响规律。分析了工具的高频振动、旋转以及机床进给三种运动综合作用下超声波铣削加工的材料去除机理，在传统超声波加工机理以及材料去除率模型的基础上，基于压痕断裂理论，建立了超声波铣削加工材料去除率理论模型。该模型可用于仿真实验研究及预测超声波铣削加工中的材料去除率。     

An investigation into material-induced surface roughness in ultra-precision milling

This paper presents a theoretical and experimental investigation into the effect of the workpiece material on surface roughness in the ultra-precision milling process. The influences of material swelling and tool-tip vibration on surface generation in ultra-precision raster milling are studied. A new method is proposed to characterize material-induced surface roughness on the raster-milled surface. A new parameter is defined to characterize the extent of surface roughness profile distortion induced by the materials being cut. An experiment is conducted to compare the proposed method with surface roughness parameters and power spectrum density analysis method by machining three different workpiece materials. The results show that the presence of elastic recovery improves the surface finish in ultra-precision raster milling and that, among the three materials being cut in the experiment, aluminum bronze has the greatest influence on surface finish due to its highest elastic recovery rate and hardness. The results also show that, in the case of faster feed rates, the proposed method more efficiently characterizes material-induced surface roughness.     

Numerical simulation of incremental sheet forming with considering yield surface distortion

The incremental sheet forming processes (ISF) are attracting lots of attentions due to their advantages on rapid prototyping, without special dies and short lead time. The numerical simulation can be a valid method to investigate the forming process and predict the defects. In this study, an extended fully coupled ductile damage model with mixed nonlinear hardening was used to simulate the ISF process. At the same time, the yield surface distortion was also considered in this model, which can enhance the capability of modeling metallic material behavior under complex loading paths. Afterwards, some simulations were conducted with the proposed model. Additionally, one tension-shear orthogonal loading test was assigned on the one representative element in order to investigate the loading path effect during ISF process. By comparing the equivalent plastic strain and ductile damage evolution of the blank, the influence of the yield surface distortion on the ISF process was proved.