A model of deformation of thin-wall surface parts during milling machining process

A three-dimensional finite element model was established for the milling of thin-walled parts. The physical model of the milling of the part was established using the AdvantEdge FEM software as the platform. The aluminum alloy impeller was designated as the object to be processed and the boundary conditions which met the actual machining were set. Through the solution, the physical quantities such as the three-way cutting force, the tool temperature, and the tool stress were obtained, and the calculation of the elastic deformation of the thin-walled blade of the free-form surface at the contact points between the tool and the workpiece was realized. The elastic deformation law of the thin-walled blade was then predicted. The results show that the maximum deviation between the predicted value and the actual measured machining value of the elastic deformation was 26.055 μm; the minimum deviation was 2.011 μm, with the average deviation being 10.154 μm. This shows that the prediction is in close agreement with the actual result.

Optimization of material removal strategy in milling of thin-walled parts

The optimal material removal strategy can improve a geometric accuracy and surface quality of thin-walled parts such as turbine blades and blisks in high-speed ball end milling.The dominant conception in the material removal represents the persistence of the workpiece cutting stiffness in operation to advance the machining accuracy and machining efficiency.On the basis of theoretical models of cutting stiffness and deformation,finite element method (FEM) is applied to calculate the virtual displacements of the thin-walled part under given virtual loads at the nodes of the discrete surface.With the reference of deformation distribution of the thin-walled part,the milling material removal strategy is optimized to make the best of bracing ability of still uncut material.This material removal method is summarized as the lower stiffness region removed firstly and the higher stiffness region removed next.Analytical and experimental results show the availability,which has been verified by the blade machining test in this work,for thin-walled parts to reduce cutting deformation and meliorate machining quality.

Numerical simulation analysis for deformation deviation and experimental verification for an antenna thin-wall parts considering riveting assembly with finite element method

In the process of thin-wall parts assembly for an antenna,the parts assembly deformation deviation is occurring due to the riveting assembly.In view of the riveting assembly deformation problems,it can be analyzed through transient and static simulation.In this work,the theoretical deformation model for riveting assembly is established with round head rivet.The simulation analysis for riveting deformation is carried out with the riveting assembly piece including four rivets,which comparing with the measuring points experiment results of riveting test piece through dealing with the experimental data using the point coordinate transform method and the space line fitting method.Simultaneously,the deformation deviation of the overall thin-wall parts assembly structure is analyzed through finite element simulation;and its results are verified by the measuring experiment for riveting assembly with the deformation deviation of some key points on the thin-wall parts.Through the comparison analysis,it is shown that the simulation results agree well with the experimental results,which proves the correctness and effectiveness of the theoretical analysis,simulation results and the given experiment data processing method.Through the study on the riveting assembly for thin-wall parts,it will provide a theoretical foundation for improving thin-wall parts assembly quality of large antenna in future.

Deformation Analysis and Fixture Design of Thin-walled Cylinder in Drilling Process Based on TRIZ Theory

Thin-walled cylindrical workpiece is easy to deform during machining and clamping processes due to the insufficient rigidi.Moreover,it’s also difficult to ensure the perpendicularity of flange holes during drilling process.In this paper,the element birth and death technique is used to obtain the axial deformation of the hole through finite element simulation.The measured value of the perpendicularity of the hole was compared with the simulated value to verify then the rationality of the simulation model.To reduce the perpendicularity error of the hole in the drilling process,the theory of inventive principle solution(TRIZ)was used to analyze the drilling process of thin-walled cylinder,and the corresponding fixture was developed to adjust the supporting surface height adaptively.Three different fixture supporting layout schemes were used for numerical simulation of drilling process,and the maximum,average and standard deviation of the axial deformation of the flange holes and their maximum hole perpendicularity errors were comparatively analyzed,and the optimal arrangement was optimized.The results show that the proposed deformation control strategy can effectively improve the drilling deformation of thin-walled cylindrical workpiece,thereby significantly improving the machining quality of the parts.

TC4钛合金薄壁件低温铣削变形研究

钛合金薄壁件刚性差、导热系数小,在加工过程中易产生回弹变形,直接影响其加工精度和性能。基于冰固持铣削实验和ABAQUS软件二维铣削及回弹变形有限元仿真,在温度区间[20℃,-80℃]内研究了工件温度、刀具角度和装夹方式对TC4钛合金薄壁件回弹变形的影响规律,得到不同条件下变形量、残余应力、切削力和刀具温度变化曲线。结果表明:铣削与回弹仿真可以有效预测实际加工。当工件温度从20℃降到-8℃时,TC4钛合金薄壁件的回弹变形量和残余应力分别减小了5.97%和48.61%,切削力在整个温度阶段增长了4%。当刀具角度为9°时,工件变形量最大;当刀具角度从3°增大到15°时,切削力和刀具温度分别下降了14.6%和27%。与点接触相比,面接触能够有效抑制工件变形。

环形薄壁件残余应力分布及预测

薄壁件被广泛用于军事航空等领域,曲面薄壁件由于其形状的特殊性对加工精度和变形控制的要求更是十分严格,加工完成后的残余应力重分布会影响成品零件质量。以7075-T651铝合金环形薄壁件为分析对象,通过ABAQUS仿真软件建立曲面铣削模型,使用单因素分析法,分析了铣削速度、径向切深、轴向切深和每齿进给量等工艺参数对环形薄壁件残余应力分布的影响。结果表明使用高速,小切深可将最大残余应力值减少13%~15%.通过铣削仿真数据,通过BP神经网络和GRNN神经网络,建立预测曲面最大残余应力和工艺参数之间的关系,以实现对最大残余应力值的预测,从而改善铣削质量。结果表明,BP网络训练结果的最小误差为2.3%,GRNN神经网络预测的最小误差值为0.07%,综合对比后GRNN神经网络具有更优的预测能力。

High precision and efficiency robotic milling of complex parts:Challenges,approaches and trends

Due to the advantages of large workspace,low cost and the integrated vision/force sensing,robotic milling has become an important way for machining of complex parts.In recent years,many scholars have studied the problems existing in the applications of robotic milling,and lots of results have been made in the dynamics,pose planning,deformation control etc.,which provides theoretical guidance for high precision and high efficiency of robotic milling.From the perspective of complex parts robotic milling,this paper focuses on machining process planning and control techniques including the analysis of the robot-workspace,robot trajectory planning,vibration monitoring and control,deformation monitoring and compensation.As well as the principles of these technologies such as robot stiffness characteristics,dynamic characteristics,chatter mechanisms,and deformation mechanisms.The methods and characteristics related to the theory and technology of robotic milling of complex parts are summarized systematically.The latest research progress and achievements in the relevant fields are reviewed.It is hoped that the challenges,strategies and development related to robotic milling could be clarified through the carding work in this paper,so as to promote the application of related theories and technologies in high efficiency and precision intelligent milling with robot for complex parts.

航空航天薄壁件铣削过程加工状态监测研究进展

对切削加工状态进行精准监测,是实现航空航天薄壁件加工变形控制的重要保障。围绕航空航天薄壁件铣削加工状态监测的最新研究进展进行了评述,详细介绍了建立加工状态监测模型的关键技术与方法,包括加工信息采集处理、特征提取和特征融合。归纳了学者们在薄壁件加工过程中对刀具磨破损、铣削颤振、铣削变形等具体状态监测的研究进展。基于数字孪生技术,构建了面向薄壁件铣削加工状态监测的优化系统。最后,根据现阶段本领域发展状况对薄壁件铣削加工状态监测进行了展望。

钛合金薄壁件超声振动辅助铣削工艺研究

在钛合金薄壁件的铣削加工过程中,存在薄壁件变形大、加工精度低等问题,为此,提出了一种基于超声振动的辅助铣削加工工艺方法。首先,分析了钛合金材料的切削变形机理,得到了影响工件变形的关键因素,为后续参数指标分析提供参考;然后,利用ABAQUS有限元仿真软件,对钛合金薄壁件的形变和受力情况进行了分析,讨论了超声振动的作用机理及其对切削力的影响;最后,在超声辅助条件下,通过单因素试验,研究了不同工艺参数对薄壁件铣削形变量的影响规律。研究结果表明:超声振动辅助加工可有效解决薄壁件铣削变形问题,大幅提高其加工精度;随着主轴转速和超声功率的增加,薄壁件的变形量呈逐渐降低的趋势;而随着进给速度的增加,薄壁变形量呈逐渐增加的趋势。该试验结果与仿真结果基本一致,与理论值的平均误差在5%以内,由此可见,该结论可为钛合金薄壁件铣削加工中参数的选择和优化提供参考。

航空铝合金薄壁件加工变形的分析与工艺方案设计

飞机整体结构件存在结构复杂、薄壁部位多和零件本身要求精度高等特点,在高速铣削过程中极易发生变形,使零件尺寸超差。以飞机舱门零件为研究对象,主要分析影响铝合金加工变形的影响因素,根据零件的结构特点制定合理的加工工艺方案,选取合理的加工参数,确保工艺过程的合理性和有效性,同时确保零件的尺寸合格,保证产品质量。

ABAQUS二次开发在列车薄壁框体零件铣削变形预测中的应用

针对列车薄壁框体零件在铣削加工中易产生变形且变形无法直接预测的难题,通过Python脚本语言对ABAQUS有限元软件进行二次开发,将实际铣削力简化为静态铣削力,建立了人机交互、参数化建模的“日”型薄壁框体零件铣削变形预测插件,利用插件对比研究了无填充情况以及分别使用纯石蜡、聚氨酯填充加固后的零件侧壁铣削加工变形量。结果表明:纯石蜡填充加固变形最小,聚氨酯泡沫填充加固次之,无填充时加工变形最大。该研究为减小框类零件加工制造过程中的铣削变形提供了方法,同时为其他相关领域的二次开发提供参考。

薄壁整体结构件的高速铣削

概括分析了薄壁整体结构件切削加工的特点和难点.以高速铣削铝合金三连波导试件为例,通过采用适当的装夹方法,合理安排工序,优化铣削方式和走刀路线,合理选用刀具,优化切削用量,合理冷却润滑,在控制变形使加工质量符合要求的前提下,省略了中间热处理工序,加工时间低于普通铣削时间的三分之一.实践经验和试验数据表明,高速铣削薄壁整体结构件应采用高切削速度、大进给速度及小轴向切深,可供推广应用高速铣削之参考.

薄壁件残余应力变形仿真预测与切削参数优化

针对薄壁件铣削残余应力变形难以准确预测的问题,提出了一种仿真预测方法,并在此基础上研究了薄壁件铣削切削参数优化方法。首先,提出了基于工况映射与薄壳应力贴合的残余应力变形仿真预测方法,实验结果表明该方法能够有效预测薄壁件的加工残余应力变形。在此基础上,利用支持向量回归机建立了基于切削参数的残余应力变形响应预测模型;然后,根据所建立的预测模型,采用遗传算法,以残余应力变形为约束、最大加工效率为目标对工艺参数进行优化。结果分析表明,该优化方法获得了最优的加工参数。

铝合金薄壁件侧壁加工变形有限元分析

在分析现有文献有关铣削加工力学模型的基础上,利用有限元分析软件ANSYS10.0,针对铝合金薄壁板进行铣削力求值及变形分析。对薄壁件加工变形有限元分析过程进行关键技术讨论,为实际切削做出理论性的探索。

基于刀具轨迹的扭曲薄壁件加工仿真与实验

为了解决叶片类扭曲薄壁件铣削加工的传统仿真方法中不按实际走刀轨迹进行载荷加载而导致模拟变形量与实际变形量之间误差较大且变形区域不准确等问题,提出了一种基于数控程序生成的刀具轨迹对叶片类扭曲曲面薄壁件铣削加工进行有限元模拟的方法。以某型发动机装机叶片的全尺寸三维结构模型为例,结合数控刀具轨迹进行了侧铣、翻面铣、螺旋铣3种加工方式下的铣削过程仿真模拟。获得了该类零件在3种铣削方式下的应力分布和变形情况,确定了发生弯扭弹性变形的区域和变形量。最后,结合相关铣削实验,验证了该仿真分析方法的正确性及有效性。

航空铝合金薄壁件铣削变形预测研究

铝合金比强度较高,广泛应用于航空航天、精密仪器和武器等行业,这些行业的零件多是薄壁件,其刚度较差,加工过程中易产生变形而使加工精度降低。为提高薄壁零件加工精度,需对其加工过程中的变形量精确预测。基于此,以J-C本构方程为基础,考虑材料热力学动态性能和断裂准则对铣削变形的影响,建立薄壁零件铣削变形量预测模型。利用UG软件建立铝合金7050-T7451薄壁特征工件。利用Deform-3D对材料本构模型、切屑分离和切屑断裂等进行描述,形成铣削加工有限元模型,对铣削变形量进行预测。进行薄壁件铣削试验,对比仿真预测结果与实验测量结果,证明了预测模型的可行性。

薄壁零件铣削分析及变形研究

以Ti6Al4V钛合金为研究对象,对薄壁件的铣削过程从解析、仿真和试验三个方面进行对比研究。在力学分析的基础上建立了整体立铣刀的瞬态切削力模型,在立式铣床上对该解析模型进行了试验验证,采用有限元方法分析了y向力对薄壁零件加工表面法向上变形的影响,采用MATLAB遗传算法以最小切削力等为目标对铣削参数进行了优化。

钛合金薄壁微铣削精度研究现状与发展趋势

随着航空、航天、船舶等工程领域对具有薄壁结构的钛合金零件需求的不断提高,加工效率相对较高且适用于曲面等复杂几何形状制造的微铣削加工方法在钛合金薄壁加工中获得了广泛的应用。然而由于其刚度较低,在微铣削加工钛合金薄壁时极易产生工件变形、失稳和振动等问题,并导致加工精度的下降。为此从理论建模、有限元仿真和试验测量三个方面分析了国内外弱刚度金属薄壁微铣削技术研究的现状。相关研究表明,在加工过程中对薄壁变形进行准确预测对于薄壁微铣削加工误差补偿模型的建立与薄壁加工精度的提高具有重要意义。并指出,在获得数学规律的基础上对薄壁微铣削加工变形和该变形对加工精度造成的影响之间蕴含的物理关系仍有待进一步的研究。

薄壁框体零件数控铣削加工变形工艺控制策略

以某大型精密仪器上的一个薄壁框体零件为例,通过分析零件特点,采用制定优化的工艺路线、设计合理的装夹方式、优选切削刀具以及优化切削方式与走刀路径等工艺控制策略,实现了在普通数控铣削机床上加工大型薄壁框体类零件,并有效减少了加工变形。该方法对同类薄壁框体零件的数控铣削加工具有一定的指导意义和参考价值。

薄壁零件数控铣削加工工艺技术研究

针对薄壁类零件加工的困境,在分析了加工变形的主要因素,即工艺系统刚度、零件结构、工艺路线、走刀策略及工件装夹等的基础上,提出了控制零件加工变形,提高工件精度的工艺技术方案,对此类零件的数控加工有一定的参考作用。