龙门加工中心主轴滑枕结构有限元分析技术研究

龙门加工中心主轴滑枕结构是连接刀具和机床的一个重要部件,其受切削力和受热变形将直接影响刀具的加工精度.通过建立龙门加工中心主轴滑枕结构的有限元分析模型,在计算热源发热量以及主轴滑枕结构热边界条件的基础上,利用ANSYS有限元分析软件在其工作状态下进行切削力变形分析、稳态热变形分析以及热-结构耦合分析.得到了主轴不同转速条件下主轴滑枕结构热态性能及刀盘直径方向变形规律,为该型龙门加工中心主轴滑枕结构优化设计和热变形补偿提供了理论依据.     

大型数控落地镗铣床主轴箱的有限元分析

通过三维软件建立了大型数控落地镗铣床主轴箱的三维模型,采用有限元软件建立了有限元计算模型,并进行了主轴箱的静态刚强度分析,计算了主轴箱的应力和变形情况.通过模态分析,计算了主轴箱1至10阶的固有频率和振型.分析结果表明,现有主轴箱的设计模型刚、强度较好,主轴箱的第1阶固有频率较低,相邻阶次的固有频率差别较大.     

加工中心主轴系统的热变形分析与有限元计算

以TH6350卧式加工中心为研究对象,构建了一套基于虚拟仪器系统的加工中心主轴系统温度场和热误差测量系统,测出了加工中心主轴系统的温度场和各项热变形.建立了基于I-DEAS的加工中心主轴系统的温度场和热变形有限元模型,计算出了主轴系统的温度场和热变形,计算结果与实测值得到了较好的吻合,研究结果为加工中心的改进设计、温度控制和误差补偿提供了理论依据.     

加工中心主轴系统的热变形分析与有限元计算

以TH6350卧式加工中心为研究对象,构建了一套基于虚拟仪器系统的加工中心主轴系统温度场和热误差测量系统,测出了加工中心主轴系统的温度场和各项热变形.建立了基于I-DEAS的加工中心主轴系统的温度场和热变形有限元模型,得到了主轴系统的温度场和热变形分布及其计算结果,计算结果与实测值得到了较好的吻合,研究结果为加工中心的改进设计、温度控制和误差补偿提供了理论依据.     

龙门加工中心主轴系统热态特性分析

建立了龙门加工中心主轴系统的有限元模型,计算了主轴轴承的发热量以及主轴系统各个表面的对流换热系数,利用ANSYS对其温度场进行有限元分析,并利用ANSYS中的耦合场分析计算出主轴系统的热变形。计算结果表明：主轴系统在一定载荷下以3000r／min的速度运转时,需要2h45min可达到热平衡状态;最高温升出现在前端轴承安装处,最大热变形达21．7μm。分析结果为主轴系统结构优化设计以及冷却、补偿系统的设计提供了一定依据。     

最不利工况下大型数控机床主轴的强度计算

本文根据某大型数控机床主轴不等截面及主轴工作时轴承支座产生小弹性变形的特征建立主轴计算模型，并以超静定法及强度理论计算及校验最不利工况下机床主轴的强度。本文介绍的计算方法对同类机床主轴的设计、强度及刚度校验具有实际参考价值。     

加工中心主轴部件及其主轴箱的热特性有限元分析

现代机械工业对机床精度提出了越来越高的要求.机床主轴部件和主轴箱的热特性是影响机床精度的主要因素之一.文章建立了加工中心主轴部件及其主轴箱的温度场模型并进行了数字模拟仿真.首先预测了机床主轴部件的热平衡时间能,并以温度曲线的形式表示出来,然后计算出主轴部件和主轴箱的热变形.依据这些我们能够得到主轴的轴向和径向误差,为主轴部件的设计计算奠定了基础.     

五坐标龙门加工中心主轴系统热特性的数值分析

根据A、C双摆头五坐标龙门加工中心的工作特点,基于热弹性力学和有限元理论,建立热力耦合变形的有限元方程.用该方程对主轴系统热特性进行数值分析,在确定内部热源、传热途径和边界条件的基础上,计算得到稳态时的主轴系统的温度场分布和热变形值,并对结果进行评价,为A、C双摆头主轴系统的设计提供技术支持.     

V400型柔性制造模块主轴单元的计算机仿真与分析

建立了柔性制造模块主轴单元的模型并完成装配与运动仿真,利用ANSYS软件对主轴的静态和动态特性进行计算,获得了静态应力分布、变形以及固有频率、振型、临界转速等数据.计算结果表明主轴所承受的最大静态应力远小于材料的屈服强度,静态变形满足加工要求,临界转速大于主轴的最高转速,不会发生共振.     

高速电主轴单元的热-结构性能虚拟仿真分析

主轴单元的热变形是高速加工中影响精度的主要因素。本文利用大型有限元分析软件ANSYS对高速电主轴进行了热-结构耦合分析。计算结果显示，设计的高速电主轴单元主轴轴承、主轴前端温升理想，工作端轴向热位移很小。这表明设计的电主轴具有良好的热-结构性能，可以满足加工精度要求。     

凸轮专用数控机床主轴的优化设计

本文以最小主轴重量及主轴前端挠度为优化目标，采用统一目标的线性组合法，引入加权因子，建立了一个统一的优化目标函数，对机床主轴进行了多目标优化设计，使优化结果更符合实际。     

Cutting Force Estimation by Measuring Spindle Displacement in Milling Process

A cylindrical capacitive displacement sensor (CCDS) was developed and applied for monitoring end milling processes. Dynamic characteristics of a spindle-assembly were measured using the CCDS and a designed magnetic exciter. The technique to extract the spindle displacement component caused only by cutting from the measured signals using the CCDS was proposed in the paper. For the quantitative estimation of dynamic cutting forces from the measured signals, a mechanistic model considering tool deflection, which is derived from the dynamics of the spindle tool system, was proposed.     

High frequency bandwidth cutting force measurement in milling using capacitance displacement sensors

This article presents a method of measuring cutting forces from the displacements of rotating spindle shafts. A capacitance displacement sensor is integrated into the spindle and measures static and dynamic variations of the gap between the sensor head and the rotating spindle shaft under cutting load. To calibrate the sensing system, the tool is loaded statically while the deflection of the tool is measured with the capacitance probe. With this calibration, the displacement sensor can be used as an indirect force sensor. However, the measurement bandwidth is limited by the natural modes of the spindle structure. If cutting force frequency contents are within the range of the natural modes of the spindle structure or higher, the measurements are distorted due to the dynamic characteristics of the spindle system. In order to increase the bandwidth of the indirect force sensor by compensating for the spindle dynamics, the design of a Kalman filter scheme, which is based on the frequency response function (FRF) of the displacement sensor system to the cutting force, is presented in this paper. With the suggested sensing and signal processing method, the frequency bandwidth of the sensor system is increased significantly, from 350 to approximately 1000 Hz. The proposed indirect force sensor system is tested experimentally by conducting cutting tests up to 12,000 rpm with a five-fluted end mill. Besides cutting forces, the measured displacements can also be affected by factors such as roundness errors, unbalance at different speeds, or dilatation of the spindle shaft due to temperature variations. Methods to compensate for these disturbing effects are also described in the paper.     

Optimum design of headstocks of precision lathes

The optimum designs of headstocks of precision lathes are studied. Three different outer shapes of headstocks are explored. Thermal deformations due to heat generated by spindle bearings are considered. The objective is to minimise the overall deflection of the workpiece at the cutting point. The constraint is to force the fundamental natural frequency much greater than the working frequency in order to reduce dynamic deflections. The design variables include the shape dimensions, the locations of the spindle bearings, the stiffnesses of the spindle bearings, the dimensions of the fins and the locations of the fins. The genetic algorithm is utilised to solve these mixed-variable optimisation problems. Optimum solutions for the three different types of headstocks are found and discussed.     

落地铣镗床主轴系统精度补偿技术研究

分析了落地铣镗床主轴系统精度补偿的几种方法,针对滑枕移动导致的主轴箱重心变化、滑枕移动导致的自身挠度变化、加装附件时滑枕挠度的变化3个方面进行了阐述,生产实践表明,3种方法集成应用能有效提高机床的加工精度。     

Evaluation of the stiffness chain on the deflection of end-mills under cutting forces

This study presents the investigation of the stiffness of the system formed by the machine-tool, shank and toolholder, collet and tool. Cutting forces induce the deflection of the system, and consequently an error appears on the machined surface.Comparing values obtained from cantilever beam models applied to the cutting tool, analytical or FEM, with those experimentally obtained, large differences have been observed, which in some cases are more than 50%. For this reason, we have proceeded to evaluate the stiffness of each of the existing elements between the machine bed and the tool tip. Thus, deflections of the machine-tool, toolholder and toolholder clamping in the spindle, tool clamping in the toolholder, and tool itself, were measured experimentally under the effects of known forces.The final application is the ball-end milling of complex surfaces, an operation commonly performed in the finishing of moulds or forging dies, where errors of more than 70 μm are not unusual. A great part of this error comes from the deflection of the machine-tool assembly, spindle, shank and tool, due to the high cutting forces of the high speed machining of tempered steels. Cutting forces can be estimated using a semi-empirical approach, and from here some values of probable errors may be taken into account to check if the CNC programs are sufficiently adapted. However, a previous study of the deflection chain in the cutting process is needed, as is presented in this work.Results show that stiffness of the slender and flexible tools is 15 times lower than that of the machine and toolholder system. But this correlation is only 5–7 times lower for shorter and thicker tools.     

Development of micro milling force model and cutting parameter optimization

Taking the minimum chip thickness effect,cutter deflection,and spindle run-out into account,a micro milling force model and a method to determine the optimal micro milling parameters were developed.The micro milling force model was derived as a function of the cutting coefficients and the instantaneous projected cutting area that was determined based on the machining parameters and the rotation trajectory of the cutter edges.When an allowable micro cutter deflection is defined,the maximum allowable cutting force can be determined.The optimal machining parameters can then be computed based on the cutting force model for better machining efficiency and accuracy.To verify the proposed cutting force model and the method to determine the optimal cutting parameters,micro-milling experiments were conducted,and the results show the feasibility and effectiveness of the model and method.     

TK6920型数控铣镗床主轴箱的计算机辅助分析及改进设计

文章研究内容针对TK6920型数控铣镗床主轴箱CAD分析及优化,运用solidworks软件建立了三维CAD设计分析模型,并采用ansys有限元软件建立了有限元模型并进行静态刚强度分析.计算分析了主轴箱的应力及应变,在此基础上构建了主体结构的优化计算模型,将主轴箱进行了优化设计,尝试了新的改变约束的方法,与初始设计进行对比分析,为主轴箱的结构设计及改造提供理论依据.     

压力机用可调式凸轮控制器转轴受力分析

对压力机用可调式凸轮控制器转轴作了受力分析。通过计算寻找转轴上的应力集中点,进而确定其危险截面,为强化该轴提供力学依据。