基于模态分析的机床床身优化设计

为提高平面光学元件抛光机床的加工精度,对其床身进行模态分析,得到机床结构固有的振动特性,实现对机床床身的优化设计。首先,通过3D建模软件构建机床模型,并将其导入ANSYS有限元软件中进行模态分析,得出机床的前几阶固有频率和振型;然后,根据模态分析结果对机床横梁和立柱进行优化设计,得出优化结构;最后,对优化后结构进行模态分析,并将结果与优化前分析结果进行对比。对比可得,优化后的机床床身前三阶固有频率分别提高15.61%、14.63%和16.07%,有效提高机床稳定性,提高工件加工精度。     

汽车散热器的模态分析

采用Pro／E对散热器进行几何建模,将模型导入Hypermesh进行几何清理、网格划分等,建立有限元模型;将模型导入Nastran中进行模态分析,得到散热器在水压0．28MPa下前三阶模态振型。将前三阶共振频率与试验值相比较,验证了仿真结果的准确性。针对分析对薄弱部分提出改进措施,对散热器进一步改进提供了重要参考。     

基于ANSYS的直驱摆头动力刀架模态分析

利用三维建模软件Pro/E建立直驱摆头动力刀架的几何模型,导入到有限元分析软件ANSYS中,建立直驱摆头动力刀架的有限元模型。分别对在车削工况和铣削工况时的直驱摆头动力刀架进行模态分析,得到其前五阶固有频率和振型。直驱摆头动力刀架模态分析的结果表明其结构设计合理,在车削工况和铣削工况时均不会发生共振。该模态分析为机床工作转速的确定提供了参考依据,为直驱摆头动力刀架的设计、试验模态分析及谐响应分析等提供重要的理论支持。     

基于ANSYS Workbench的某新型吹雪车车架模态分析

应用Pro/E软件对一款新型吹雪车车架结构进行三维建模,导入ANSYS Workbench软件生成有限元模型,并对其进行模态分析,得到了吹雪车车架结构的前6阶固有频率和振型。在此基础上分析了吹雪车在不同工作状况下的振动特性,为后续吹雪车工作装置的布局和整车的优化设计提供了理论依据。     

组合机床多轴箱中间箱体的有限元模态分析

以组合机床多轴箱中间箱体为研究对象,运用Pro/E三维建模软件建立了多轴箱中间箱体的实体模型并导入ANSYS软件,在网格划分时采用智能网格划分方法,得到理想的有限元分析模型。最后利用Block Lanczos方法进行多轴箱中间箱体结构模态分析。模态分析结果对多轴箱中间箱体的设计和改进具有一定的意义。     

基于UG的扁环薄壁弹性元件的设计与仿真分析

弹性元件是微喷阀中的关键部件,其性能直接影响到微喷阀工作时的可靠性和稳定性。针对微喷阀中弹性元件的受力和变形特点,设计了一种扁环薄壁弹性元件,推导并建立了其力学模型。运用有限元分析软件UG对该弹性元件进行建模,然后将模型导入UG中的高级仿真模块,分别进行了静力学强度分析和动力学模态分析。     

基于ANSYS的二级减速器从动齿轮模态分析

以某履带二级减速器的从动齿轮为研究对象,利用SolidWorks软件对齿轮进行三维建模。通过更改文件保存类型,将模型导入ANSYS Workbench软件并对其进行网格划分,建立三维有限元模型。应用动力学模态分析得到齿轮的各阶模态固有频率和振型,为减速器动力学分析和优化设计提供必要的理论依据。     

数控机床滚动导轨结合面参数的特性分析

机床导轨结合面是影响机床特性的关键因素,在机床整机的建模分析中是必须要考虑的部分。根据滚动导轨结合面的模态试验结果和有限元分析结果,对导轨结合面的参数进行优化识别,得到导轨结合面的动刚度和阻尼,为机床整机建模分析提供了重要的依据。     

YKS5120B-3数控插齿机床身结构有限元分析

基于Pro/E建立了YKS5120B-3数控插齿机床身的三维模型,并利用Pro/E与ANSYS接口将该模型直接导入ANSYS,对床身进行了结构静、动态有限元分析,得到了床身静态应力及变形数据、前5阶模态的固有频率和振型。根据分析结果,对床身结构提出了改进方案并进行了验证。本研究为YKS5120B-3数控插齿机床身设计与制造提供了一种理论指导。     

CK5116数控立式车床整机模态分析

针对某机床厂生产的CK5116数控立式车床在振动过程中存在振动,噪声大等问题,对该机床了进行模态分析。首先采用SolidWorks软件得到整机的三维模型,建立该机床整机结构动力特征方程,通过有限元求解,得到整机的各阶固有频率和振型,同时根据各阶振型变化形态及应力集中区域,分析可能产生的共振频率,结合机床整机振动模态测试试验得到的模态参数,对比试验模态和有限元模态计算结果,除实验条件原因外,在允许的误差范围内,验证了建立的有限元模型是正确的,从而为有效控制机床整机振动噪声等问题的研究提供理论基础,为同类机床结构性能优化分析与实验提供必要的参考。     

基于SOM-Kmeans的机床能效等级评价方法

机床能效等级评价是提高能源效率的基础。现有机床能效评价方法多运用能量利用率和比能等指标评价特定加工过程能效,未考虑加工能力对机床能效评价的影响,致使无法综合评价机床能效等级。为此,从机床加工能力和能耗特性角度构建机床能效等级评价指标,提出基于自组织映射神经网络-K均值(SOM-Kmeans)的机床能效等级评价方法。首先,分析机床加工能力特性和时段能耗特性,构建机床加工能力指标和多时段能耗特性指标;其次,运用SOM-Kmeans对机床能效信息进行聚类分析,并采用主成分分析法(PCA)对机床能效等级进行综合评价;最后,通过实际案例验证了所提方法的有效性和实用性。     

Integrated simulation method for interaction between manufacturing process and machine tool

The interaction between the machining process and the machine tool (IMPMT) plays an important role on high precision components manufacturing. However, most researches are focused on the machining process or the machine tool separately, and the interaction between them has been always overlooked. In this paper, a novel simplified method is proposed to realize the simulation of IMPMT by combining use the finite element method and state space method. In this method, the transfer function of the machine tool is built as a small state space. The small state space is obtained from the complicated finite element model of the whole machine tool. Furthermore, the control system of the machine tool is integrated with the transfer function of the machine tool to generate the cutting trajectory. Then, the tool tip response under the cutting force is used to predict the machined surface. Finally, a case study is carried out for a fly-cutting machining process, the dynamic response analysis of an ultra-precision fly-cutting machine tool and the machined surface verifies the effectiveness of this method. This research proposes a simplified method to study the IMPMT, the relationships between the machining process and the machine tool are established and the surface generation is obtained.     

恒定加工条件及定期补偿下的刀具渐变可靠性灵敏度分析方法

据统计,由刀具失效导致的停机时间超过机床被迫停机时间的1/3,故开展刀具渐变可靠性及其灵敏度分析的研究对提高机床的运行可靠性具有重要意义。采用连续时间、连续状态、具有非减独立增量的非平稳Gamma过程描述刀具磨损量的变化过程。根据加工偏差不大于机床给定加工精度的原则,构建刀具制造及磨损量检测有无误差两种情形下、恒定加工条件及定期补偿的刀具渐变状态函数,由此推导出相应的渐变可靠度模型。在此基础上给出渐变可靠度模型对各个参数的灵敏度计算方程。通过数值实例分析,阐述了通过提出的渐变可靠性模型及灵敏度分析方法提高刀具运行可靠性的应用过程。这一工作为提高恒定加工条件及定期补偿下刀具的运行可靠性提供切实可行的理论和方法基础。     

基于灵敏度分析的五面加工中心床身结构优化设计

机床床身是机床的重要部件,它起着支撑立柱、工作台等部件的作用,其性能的好坏直接影响到机床的加工精度。在对HX7910五面加工中心床身结构动态优化设计过程中,建立HX7910五面加工中心床身的有限元模型,分析了其前六阶模态。根据分析结果确定筋板为优化对象,采用灵敏度优化法首先对床身内部筋板结构参数进行动态灵敏度分析。在灵敏度分析基础上,进行结构优化设计,得到了较优的结构参数,提高了加工中心床身的动态特性,从而提高床身的性能。     

Cutting tool wear detection using multiclass logical analysis of data

This article presents a new tool wear multiclass detection method. Based on the experimental data, tool wear classes are defined using the Douglas–Peucker algorithm. Logical analysis of data (LAD) is then used as machine learning, pattern recognition technique for double objectives of detecting the present tool wear class based on the recent sensors' readings of the time-dependent machining variables, and deriving new information about the intercorrelation between the tool wear and the machining variables, by doing pattern analysis. LAD is a data-driven technique which relies on combinatorial optimization and pattern recognition. The accuracy of LAD is compared to that of an artificial neural network (ANN) technique, since ANN is the most familiar machine learning technique. The proposed method is applied to experimental data those are gathered under various machining conditions. The results show that the proposed method detects the tool wear class correctly and with high accuracy.     

机床支承件结构设计方案优化选择

对机床支承件截面形状和肋板布局形式进行分析对比,以某型号立式加工中心的立柱为例,在ANSYS Workbench平台上对其进行静力学分析及模态分析,比较不同肋板布置方案对立柱刚度及振动特性的影响,为机床支承件结构设计方案优化选择提供参考。     

Process parameter definition with respect to the behaviour of complex kinematic machine tools

The definition of machining processes with respect to complex kinematic machine tool behaviour involves the control of machine accuracy and kinematic performances. The aim is to propose process settings and tool paths which guarantee the required machining quality while maximizing productivity. This article presents an experimental protocol which enables the determination of machine tool structure behaviours which have an influence on machining quality. In parallel, an experimental analysis of the different kinds of settings which can improve machining quality is carried out. Two kinds of settings appear: the first class of settings improves machining quality or machining time, and the second class has an antagonistic influence on machining quality and machining time. Thus, the definition of the second class of settings arises from an optimisation between first-order defects, second-order defects and machining time. The developed method is illustrated on a parallel kinematic machine tool, the Tripteor X7. Note that this study is a first step towards controlling machine tool behaviour during machining.     

Suppression of thermal deformation of machine tool spindle using TiC-Fe composite

The minimization of error generation in machine tool spindle is important because high-speed and ultra-precision machining are extensively utilized in industrial fields. The thermal deformation of the machine tool spindle generated by the frictional heat between the outer and inner bearings can deteriorate the machining accuracy. In this study, a TiC−SUS431 composite was fabricated using the liquid pressing infiltration method to suppress thermal deformation, and its thermal properties were obtained by thermal characteristic tests. For the transient thermal analysis with finite element analysis, the parameters of the machine tool spindle-bearing model were selected, and the boundary conditions were calculated. The temperature and thermal deformation of the analysis model were compared by applying SCM415 and TiC−SUS431 to the material of the machine tool spindle and changing the rotation speed. From the analysis results, it was demonstrated that the TiC−SUS431 machine tool spindle can improve the machining accuracy by minimizing the spindle thermal deformation.

     

Simultaneous geometric error identification of rotary axis and tool setting in an ultra-precision 5-axis machine tool using on-machine measurement

This paper presents a method to identify the position independent geometric errors of rotary axis and tool setting simultaneously using on-machine measurement. Reducing geometric errors of an ultra-precision five-axis machine tool is a key to improve machining accuracy. Five-axis machines are more complicated and less rigid than three axis machine tools, which leads to inevitable geometric errors of the rotary axis. Position deviation in the process of installing a tool on the rotary axis magnifies the machining error. Moreover, an ultra-precision machine tool, which is capable of machining part within sub-micrometer accuracy, is relatively more sensitive to the errors than a conventional machine tool. To improve machining performance, the error components must be identified and compensated. While previous approaches have only measured and identified the geometric errors on the rotary axis without considering errors induced in tool setting, this study identifies the geometric errors of the rotary axis and tool setting. The error components are calculated from a geometric error model. The model presents the error components in a function of tool position and angle of the rotary axis. An approach using on-machine measurement is proposed to measure the tool position in the range of 10 s nm. Simulation is conducted to check the sensitivity of the method to noise. The model is validated through experiments. Uncertainty analysis is also presented to validate the confidence of the error identification.     

Dynamic characterization of machining systems

In the working space model of machining, an experimental procedure is implemented to determine the elastic behaviour of the machining system. In this paper, a dynamic characterization and vibration analysis has long been used for the detection and identification of the machine tool condition. The natural frequencies of the lathe machining system are required (Ernault HN400??France) according to three different situations with no cutting process are acquired. The system modal analysis is used to identify the natural frequencies. These frequencies are then compared to the ones obtained on the spindle numerical model by finite element method. This work is validated by experimental tests based on measures of the lathe machine tool frequencies domain. The main objective is to identify a procedure giving the natural frequency values for the machine tool components, in order to establish a better condition in the cutting process of the machine tool.