基于有限元法的机床主轴长度分析与设计

在数控机床的整机设计中,主轴部件作为数控机床的重要部件,其设计是最为关键的。为了使数控机床的主轴部件具有刚度高、振动小、变形小、噪声低以及良好的抵抗受迫振动和自激振动能力的动态性能,在进行结构设计时就必须考虑各种因素可能导致的主轴部件的变形,并采取有效的防范措施。本文利用现代分析方法——有限元法针对数控车床主轴轴向长度的影响进行优化设计,提出了更好的设计方案。     

高速铣齿机床主轴箱结构的有限元法分析

讨论了利用有限元单元法对高速铣齿机床主轴箱的结构进行分析的方法。采用Pro／E建立主轴箱的实体模型,通过ANSYS软件提供的数据接口程序将其导入ANSYS中,计算出静态应力、固有频率和振型,为动态分析、优化设计提供理论依据。     

基于Romax的镗铣复合加工中心主轴轴承配置方案优化设计研究

在机械传动系统设计与分析软件Romax中,以昆明机床厂THM65160精密镗铣复合加工中心为研究实例,构建了主轴系统的仿真模型,分析获得了主轴的弯曲应力、径向位移以及主轴轴承的寿命.并针对THM65160主轴原始设计中存在着刚度不足问题,通过定量分析轴承配置形式与主轴轴端径向位移之间的关系,给出了主轴轴承配置的优化方案,为实际设计生产提供了理论基础.     

数控螺旋锥齿轮铣齿机主轴系统的有限元分析

利用有限元分析软件ANSYS,对一台数控螺旋锥齿轮铣齿机的主轴系统进行静力分析、模态分析和谐响应分析,获得其静态的变形、各阶固有频率、振型及其特定工况下的位移频率响应曲线.为主轴的动态优化设计提供依据.     

Analysis of step journal bearings by a semianalytical finite element method

An analysis of multistep finite length eccentric journal bearings by a semianalytical finite element method is presented. Numerical results for the pressure distribution, Sommerfeld number and attitude angle in the laminar regime are compared with experimental results for three kinds of bearings whose step parameters are 1.0, 2.0 and 3.0. Good agreement is obtained between the numerical and experimental results.     

加工机架的镗刀杆与机床主轴的连接工装改进

根据加工机架的镗床刀杆特点,分析了改进前工装存在的问题,结合现有的工装设备,对连接工装进行改进。加工实践表明,依靠固定卡的连接方法不适合生产需要,而靠螺栓把紧的连接方式适合生产需要。改进后的连接工装能够有效的控制机架内孔的同轴度要求,保证机架加工精度达到设计要求。     

数控铣床滑枕有限元分析及试验研究

采用有限元和试验的方法,对TX6916落地镗铣床方滑枕进行了动态特性分析.采用有限元分析软件ANSYS对方滑枕进行模态分析,在三维实体模型的基础上建立了模态分析的有限元模型,研究了方滑枕的无阻尼自由振动,求解得出前五阶固有振动频率和相应的主振型.通过试验测试数据和有限元计算结果对比分析,验证了有限元模型的合理性,并对误差原因进行讨论,为该型镗铣床的进一步动力学研究及其优化设计提供了重要依据.     

加工中心动态特性的有限元分析及实验研究

在某加工中心有限元模型中引入用户自定义单元来模拟结合面的刚度,并用ANSYS对其进行模态分析.同时对加工中心的龙门架、滑鞍和主轴箱进行模态实验.并将实验所得数据与有限元计算结果进行比较,得到二者频率值相差不大,从而验证了理论计算的可靠性,并为加工中心结构薄弱环节的进一步改进提供了参考.     

超宽热压机框架有限元分析及结构优化

以某公司生产的4英尺×9英尺横向进板超宽热压机为分析对象,采用有限元方法对热压机框架板进行了应力状态与形变分析,提取出框架板在关键位置处的应力及位移数据;并以APDL建立了框架板参数化有限元模型,结合ANSYS优化设计模块,对框架板结构参数进行了优化计算,在以节约材料和保证其性能的前提下,确定了单块框架板的最优结构,并对优化参数后的框架板进行了有限元分析,验证了优化结果.     

An experimental and coupled thermo-mechanical finite element study of heat partition effects in machining

A better understanding of heat partition between the tool and the chip is required in order to produce more realistic finite element (FE) models of machining processes. The objectives are to use these FE models to optimise the cutting process for longer tool life and better surface integrity. In this work, orthogonal cutting of AISI/SAE 4140 steel was performed with tungsten-based cemented carbide cutting inserts at cutting speeds ranging between 100 and 628 m/min with a feed rate of 0.1 mm/rev and a constant depth of cut of 2.5 mm. Cutting temperatures were measured experimentally using an infrared thermal imaging camera. Chip formation was simulated using a fully coupled thermo-mechanical finite element model. The results from cutting tests were used to validate the model in terms of deformed chip thickness and cutting forces. The coupled thermo-mechanical model was then utilised to evaluate the sensitivity of the model output to the specified value of heat partition. The results clearly show that over a wide range of cutting speeds, the accuracy of finite element model output such as chip morphology, tool–chip interface temperature, von Mises stresses and the tool–chip contact length are significantly dependent on the specified value of heat partition.     

某车架有限元建模及仿真研究

本文根据有限元方法建立了某半挂车车架结构的有限元模型,并确定其载荷的简化和施加方法,在此基础上分别探讨了该车架的静态强度和动态特性,并对该车架的动态特性进行了分析研究。结果表明该车架能够满足各种性能要求,在额定载荷作用下,车架的局部应力接近材料的屈服应力,但是车架结构整体应力较小,为后续车架的优化设及其轻量化研究计提供了重要的理论依据。     

基于有限元法的800MN模锻机工装桁架结构分析

工装桁架为800 MN模锻机安装过程中的辅助结构,在考虑工装桁架C形板安装细节的基础上,应用Ansys软件对工装桁架在C形板安装过程中的力学行为进行有限元分析,计算工装桁架结构在C形板安装过程中的最大应力和最大位移,求出桁架结构的临界失稳载荷,为今后大型设备的辅助安装提供参考。     

A novel 5-DOFs dynamic model of aerostatic spindle considering the effect of process damping in ultra-precision machining

The existing aerostatic spindle dynamic model only analyses the effects of mass imbalance and external load, ignoring the influence of cutting system on the spindle dynamic characteristics under cutting conditions. In this paper, a 5-DOFs aerostatic spindle dynamic model is established considering the influence of the micro-scale non-linear dynamic performance of the aerostatic spindle and cutting process damping. First, an analytical identification model of process damping with blunt circular cutter is established. Then, the micro-scale dynamic characteristics of the aerostatic spindle are analyzed and a 5-DOFs aerostatic spindle dynamic model is established considering the influence of process damping. Finally, the model is simulated and the influence of process damping on the dynamic characteristics of aerostatic spindle is analyzed. The simulation results show that the process damping of the cutting system has a significant influence on the dynamic characteristics of the aerostatic spindle. This study can provide theoretical guidance for coupling research of cutting system and spindle system.

     

Investigation of the fracture characteristics of the interfacial bond between bone and cement: experimental and finite element approaches

This study integrated the finite element method, fracture mechanics, and three-point bending test to investigate the fracture characteristics of the interfacial bond between bone and cement. The fracture tests indicated that the interfacial fracture toughness of the bone/cement specimens was 0.34 MN/m^3/2, with a standard deviation of 0.11 MN/m^3/2, which was in good agreement with the experimental data available in the literature. A finite element model of the experimental testing specimen was used to predict the critical stress intensity factor (SIF) at the fracture load by the proposed fracture analysis method. The critical SIF of the opening mode of the interface crack was 0.392 MN/m^3/2, which was slightly higher than the fracture toughness obtained in the experiment. Additionally, considering the coupled effects of the crack opening mode and shearing mode, the critical effective SIF was 0.411 MN/m^3/2, with a phase angle of 17.2°. Comparisons of the results obtained from the bending test and numerical analysis made it obvious that the fracture characteristics of the bonded interface between the bone and cement could be accurately predicted by the proposed model. With this analysis model, a realistic investigation on the debonding behavior of cemented artificial prosthetic components is highly expected.     

Analysis by the finite element method of hydrodynamic bearings operating in the laminar and superlaminar regimes

By adopting the non-linear theory proposed by Elrod and Ng, the generalized Navier-Stokes equations were modified and solved numerically for the flow field in the clearance space of a journal bearing.The performance characteristics of a finite circular hydrodynamic bearing (aspect ratio L/D = 1) were studied in terms of the Sommerfeld number, attitude angle, oil flow, friction coefficient and temperature rise parameter at various eccentricities for Reynolds' numbers up to 13 300.     

二维调节架支撑钢架的有限元计算分析

根据二维调节架支撑钢架的结构设计方案，利用结构分析软件ANSYS，建立了结构的有限元模型，求得了支撑钢架的变形、应力值以及前几阶自振频率和振型图，为结构设计提供了科学验证，并为改进和优化结构提供了理论依据。     

Modelling and experimental investigation of spindle and cutter dynamics for a high-precision machining center

The geometric quality of high-precision parts is highly dependent on the dynamic performance of the entire machining system, which is determined by the interrelated dynamics of machine tool mechanical structure and cutting process. This performance is of great importance in advanced, high-precision manufacturing processes, including aerospace and biomedical applications. In this paper, the dynamics of the combined spindle/cutter system, a major component of any machine tool, is identified using impact testing techniques and is successfully approximated by a second-order linear model. Results of computer simulations of machining processes that include the identified spindle/cutter dynamics show a significant influence on the quality of the final product. From this, it is concluded that, for precision workpieces, the dynamics of the spindle and cutter system will have to be taken into account in order to improve future machining controls and processes.     

Dynamic analysis of a car chassis frame using the finite element method

An automobile chassis structure has been analysed dynamically using the finite element method, and the results have been compared with those obtained experimentally. The first nine natural resonances of the frame up to 100 Hz have been examined.

Two basic methods of predicting the dynamic response have been used involving different computing techniques. Since computing costs are of prime importance in any practical application of the finite element method, the modes of operation of the programs have been briefly described and running times are compared for a number of structural idealizations.

The results presented show for a relatively simple structure that simple idealization concepts can give good results.     

一种客车车架结构的有限元分析

为了得到某种客车车架的静态和动态特性,运用有限元软件建立了该种车架的模型,并对该车型车架进行了静力学分析及模态分析,从而得到了车架的变形、应力分布及其固有频率和振型。据此,提出了几种该种车架机构上的改进方案。研究分析结果表明,该方法为进一步改善该车架的结构提供参考。     

Simulation of dynamic properties of a spindle and tool system coupled with a machine tool frame

The cutting performance relates to the dynamic properties of the whole system of the tool, spindle, and machine tool frame. The impact of the machine frame properties on the dynamic properties at the tool end point is studied both experimentally and using a coupled simulation model. Coupled model of the whole mechanical system is created as a system joining the spindle detailed model and machine frame FE model. Shift in the spindle and tool system dynamic properties, related to the machine frame properties, is proved using the coupled model. Experimental verification of the FRF evaluated at the tool is extended also by cutting tests. Good match of the simulated dynamic properties of the whole system with the real behavior is found.