机床主轴系统支承动态参数识别方法的研究

本文对传递矩阵法识别机床主轴系统支承动态参数的原理和应用进行了研究,并在此方法中引入了“拟合圆法”,以提高识别精度.用在此基础上编制的计算机程序,在主轴系统实际安装条件下,根据各测点的位移导纳试验数据,对机床主轴系统支承动态参数进行了识别计算.     

机床主轴系统支承动态参数识别方法的研究

对传递矩阵法识别机床主轴系统支承动态参数的原理和应用进行了研究，并在此方法中引入了“拟合圆法”，以提高识别精度，用在此基础编制的计算机程序，在主轴系统实际安装条件下，根据各测点的位移异纳试验数据，对机床主轴系统支承动态参数进行了识别计算。     

机床—主轴耦合系统动力学建模与模型修正

复杂精密零件的加工对机床装备的性能不断提出新的挑战。为了保证零件加工精度,有必要在设计阶段对机床整机的动态特性进行精确预测和评估。以机床主轴系统为研究对象,介绍一种机床—主轴系统耦合动力学模型,并指出该模型中存在结合面动态特性参数的辨识问题。为了修正该耦合模型,提出一种基于频率响应函数的有限元模型修正技术。采用包含平动自由度(Degree of freedom,DOF),转动DOF以及平动与转动耦合DOF的刚度矩阵来描述结合面的动态特性,通过测量结合面处的动态响应数据,辨识出高速主轴与机床之间结合面的刚度参数,从而达到模型修正的目的。试验结果表明,修正后的机床—主轴耦合模型反映出了机床结构对主轴动态特性的影响,能较好地预测主轴安装到机床上以后的动态特性,从而为高性能机床的数字化设计与制造提供理论依据。     

基于传递矩阵法的机床主轴动态特性分析

机床主轴系统的振动是限制机床加工品质和生产率进一步提高的一个主要因素.根据机床主轴系统的组成情况,利用传递矩阵法对其进行分段建模,将主轴系统简化为梁单元、刚体单元和弹簧单元的组合,并建立了系统传递矩阵,求解出主轴的固有频率和相应振型,为其动态性能的进一步优化提供了依据.     

机床基础理论讲座——第三讲 机床动态特性(下)

四、动态特性计算与优化设计 分析和解决机床中的振动问题,除用试验的方法外,还需要掌握计算的方法。六十年代以后,随着电子计算技术的发展,出现了一些新的动态特性计算方法,主要有传递矩阵法、有限元法和机械阻抗法。 1.传递矩阵法 传递矩阵法应用于计算,可以简化为梁的零、部件。它是把线性弹性系统分为几段,用矩阵表示每段的特性,再利用矩阵乘法得出表示整个系统特性的矩阵,代入边界条件,即可求出系统的固有频率和振型,掌握阻尼值时,也可以准确地求出振幅和动柔度。这种方法的基本思想是把一个本来具有分布参数的系统,近似处理为由一些集…     

上楼机床及设备的隔振研究

本文针对多层厂房内的安装机床及设备,提出了同时考虑机床弹性及安装基础动态特性的非刚性隔振系统的建模方法,应用子结构传递矩阵法推导了该复杂隔振系统的传递率,并给出了相应的功率流解析表达式,为进一步研究柔性基础上安装机床和设备的振动噪声控制提供了理论依据,并可推广应用于弹性基础上的双层隔振系统。     

上楼机床及设备的隔振研究

本文针对多层厂房内的安装机床及设备，提出了同时考虑机床弹性及安装基础动态特性的非刚性隔振系统的建模方法，应用子结构传递矩阵法推导了该复杂隔振系统的传递率，并给出相应的功率流解析表达式。为进一步研究柔性基础上安装机床和设备的振动噪声控制提供了理论依据，并可推广应用于弹性基础上的双层隔振系统。     

基于多体传递矩阵法的重型龙门机床-混凝土基础系统动力学模型

针对重型龙门机床混凝土基础严重影响整机动态特性的情况,采用多体传递矩阵法建立了重型龙门机床-混凝土基础系统动力学模型,考虑了结合面及弹性体元件的影响,分别建立了结合面及弹性体传递矩阵,通过制作不同粗糙度接触表面、应用不同型号螺栓及预紧力的法向、切向实验试件,采用静载实验方法获取了大面压的结合面参数,并植入到结合面传递矩阵中,最后通过与现场实验的对比,验证了该模型的正确性,为机床与混凝土基础的设计提供了理论依据。     

轴间耦合下多轴联动机床的位置维动态特性分析

多轴联动机床刀尖点在空间运动过程中由于机床结构构形改变和轴间耦合作用,会造成动结合部刚度的非线性变化,进而改变系统惯性矩阵、刚度矩阵元素的量值,从而导致系统动态特性的改变。以一台典型的三轴联动龙门机床为研究对象,采用集中参数法建立轴间耦合下三轴联动机床系统的动力学模型,并推导系统的动力学方程,其系数矩阵是系统运动状态的函数。利用所建模型,对系统频率和频率响应函数相对于位置参数的变化进行分析。仿真和试验结果表明:轴间耦合作用对多轴联动机床的动态特性影响较大,系统的固有频率及对应幅值与刀尖点在x轴、y轴、z轴运动位置的变化有很大关系,极端位置的固有频率相差10%左右,响应的幅值变化量可达2倍左右。     

传递矩阵法分析平面柔顺机构的振动特性

为了分析柔顺机构的动态性能和力学传递关系,提出一种新型的基于传递矩阵法的振动力学模型。柔顺机构由若干个柔性铰链与杆件顺序联接而成,采用传递矩阵法描述其力学状态量的传递关系。将柔性铰链视为拉伸和弯曲变形的弹性梁,应用材料力学理论建立反映其自振性能的传递矩阵。将杆件视为刚体,采用动量矩定理建立其动力学模型,得到描述振动刚体的传递矩阵。按照柔顺机构的联接形式,将每个元件的传递矩阵进行拼装,得到系统总传递矩阵。总传递方程以柔顺机构的边界点状态矢量为未知变量,矩阵中的元素为机构结构参数和频率的函数。应用边界条件,可得柔顺机构的特征方程,通过求解方程可得系统的固有频率和振型。将外力纳入传递矩阵,建立反映外力激励与系统的关系的扩展传递矩阵以求解系统的频率响应。通过2种常用平面柔顺机构的动态性能分析,结果表明所建立模型的正确性,能精确描述柔顺机构力学传递关系。     

机床结合部动力学建模与辨识方法的研究

针对机床结合部动力学建模与辨识过程中对子结构间耦合关系与内部激振对外部响应影响考虑不充分问题,采用频响函数矩阵建立完备的机床结合部动力学理论模型;基于力学平衡条件和位移兼容条件推导了辨识方程,提出一种新的动力学辨识方法;辨识过程中融入了子结构间耦合关系,将难测频响矩阵作为中间变量抵消,避免使用难以测量频响或估算难以测量频响所引入的方程误差。在此基础上,将辨识方程拓展至整个测量频段,构建包含辨识关系的矛盾方程,通过最小二乘法求解确定了结合部的等效动刚度,建立了结构的有限元模型。为验证方法的正确性与可行性,基于LMS试验平台进行了现场试验,获得了良好的试验效果;与缩减维度、忽略内部激振作用的建模方法进行了对比分析,结果表明本文方法具有更好的预测性。     

A NEW MODELING METHOD FOR MACHINE-FOUNDATION COUPLING SYSTEM AND ITS APPLICATION TO THE CONTROL OF POWER FLOW

０ＩＮＴＲＯＤＵＣＴＩＯＮＶｉｂｒａｔｉｏｎｔｒａｎｓｍｉｓｓｉｏｎｆｒｏｍａｍａｃｈｉｎｅｓｏｕｒｃｅｔｏｆｌｅｘｉｂｌｅｓｕｐｐｏｒｔｉｎｇｓｔｒｕｃｔｕｒｅｓａｎｄｔｈｅａｓｏｃｉａｔｅｄｓｏｕｎｄｒａｄｉａｔｉｏｎｆｒｏｍｔｈｅｖｉｂｒａｔ...     

A NEW MODELING METHOD FOR MACHINE-FOUNDATION COUPLING SYSTEM AND ITS APPLICATION TO THE CONTROL OF POWER FLOW

A new concept, namely, the equivalent mobility matrix of coupling subsystem is proposed, and the corresponding three-subsystem coupling progressive approach is explored. With the new efficient approach presented, the complexity in dealing with a more complicated dynamic coupling system is greatly reduced. The new modeling method is then combined with the theory of power flow to investigate the dynamics of the overall non-rigid isolation system from the viewpoint of energy. The interaction between the resilient machine of its main modes and the resonant behavior of the flexible foundation on power flow transmission is studied. Taking a machine tool mounted on a multi-story working plant as an example, the dynamic characteristics of the machine-foundation coupling system are analyzed, and their effects on power flow transmission are revealed under various service frequency bands. Some advisable control strategies and the design principle for machinery mounted on flexible structure are proposed.     

APPLICATION OF THE CONDITIONED REVERSE PATH METHOD

Conventional frequency response estimations often give results contaminated by the presence of non-linearities and the extraction of underlying linear system properties is thus difficult. To overcome this problem, the implementation of the Conditioned Reverse Path spectral method to the identification of single- and multi-degree-of-freedom (sdof and mdof) non-linear systems is considered, showing that conventional methods such as ‘H₁’ and ‘H₂’ lead to estimated frequency response functions which are often completely inadequate, even in absence of measurement noise. This spectral method allows to estimate the coefficients of the non-linearities away from the location of the applied excitations and also to identify the linear dynamic compliance matrix when the number of excitations is smaller than the number of response locations. This paper presents some guidelines to successfully apply this method to real non-linear systems; furthermore, the results from an experimental test over a sdof suspension system are shown.     

非对称缸垂直力加载系统研究

介绍了非对称缸垂直力加载系统,讲述了该系统的工作原理,推导出该系统的动态响应数学表达式。以Mat-lab中动态仿真工具Simulink软件包为开发工具,将其应用于该闭环控制系统的动态响应计算中,给出了考虑干扰量情况下的Simulink仿真方法。     

Fault diagnosis of complex system based on nonlinear frequency spectrum fusion

A novel fault detection and diagnosis approach is proposed for nonlinear complex systems by combining nonlinear frequency spectrum characteristics and evidence theory. In order to overcome the problem of calculated amount expansion of generalized frequency response functions, single-dimensional nonlinear output frequency response functions are used to obtain nonlinear frequency spectrum, from which, features of nonlinear frequency spectrum are extracted. The fault diagnosis model of multiple faults is given based on evidence theory. The mass functions of evidences are obtained according to the similarity among different modes. In order to solve the problem of evidence fusion in the situation of evidence confliction, a dynamic parameter conflicting evidence combination method is proposed based on the average credibility. Fault diagnosis of the transmission system of numerical control machine tool is studied through nonlinear frequency spectrum. Simulations indicate that the proposed approach has simple calculation and high recognition rate for faults.     

机床功率监控系统的数学模型及其应用

从机床能量传输数学模型出发,首次建立了机床功率信息传感型监控系统（简称机床功率监控系统）的数学模型,提出了些模型在研究机床功率信息动态响应特性,提示功率住处随切削负载率和在外界干扰信息作用下的变化规律,识别刀具磨损、破损状态,诊断机械加工故障,测试机械加工过程中的某些机械量或电量等方面有着多种功能和用途,并列举了应用此模型提示机床功率监控系统中功率信息的迟滞响应特性的实例。     

高速HSK热装工具系统结合部的参数辨识

HSK工具系统的动态特性直接影响机床的加工效率与质量,获得准确的工具系统结合部参数又是精确预测HSK工具系统动态特性的基础。将热装刀柄-刀具结合部简化为弹簧-阻尼模型,基于Timoshenko梁理论建立了HSK热装刀柄-刀具结合部的有限元模型,采用弹塑性理论辨识结合部的刚度和阻尼,获得了HSK热装刀柄-刀具结合部内沿轴向不同位置的刚度和阻尼。进而建立了HSK热装工具系统的有限元动力学模型,分析工具系统刀尖点的频响函数。最后进行了HSK热装工具系统频响函数的实验测量,与理论频响函数相比较,验证了将结合部等效为弹簧-阻尼的辨识方法的合理性和有效性。     

A FREQUENCY DOMAIN METHOD FOR ESTIMATING THE PARAMETERS OF A NON-LINEAR STRUCTURAL DYNAMIC MODEL THROUGH FEEDBACK

A unifying perspective of non-linear structural dynamic systems as linear in the open loop with non-linear feedback in the closed loop has recently been revisited by the authors. The authors have previously used feedback to derive a new formulation of frequency response function matrices of non-linear systems, which are described as modulations of nominal linear systems. The modulation creates a pseudo-separation of the linear and non-linear dynamics of the system. The present article derives a new method for estimating parameters of non-linear parametric models that uses internal feedback to account for non-linearities. The main advantage of the new formulation of non-linear system identification is its simplicity. Moreover, the method estimates the linear frequency response matrix and non-linear system parameters at forced and unforced degrees of freedom of general multiple-degree-of-freedom non-linear systems simultaneously. This article demonstrates the implementation of this method on simulated data from single- and multiple-degree-of-freedom lumped parameter models.