卧式数控机床主轴热变形影响因素分析

以卧式数控机床为对象,对机床主轴在开启冷却机与关闭冷却机状态下进行热变形测试实验,并进行了详尽分析,得到主轴在两种状态下X、Y、Z轴向热变形规律;然后建立机床实体模型,采用有限元热固耦合及流固耦合法,对数控机床的关键部件主轴部件、主轴箱部件及立柱部件分别进行热变形仿真分析,以获得影响主轴热变形规律的主要因素,为产品改进提供依据。     

组合机床典型主轴箱的设计

主轴箱是组合机床的一个部件,主要是用来按各主轴相互要求的位置,配置主轴和减速齿轮,减速齿轮将运动由动力头驱动轴传递到各主轴上,并将所须的转数传给主轴。布置在一个主轴箱内的主轴数目及位置决定于被加工零件的结构。 组合机床上主轴箱的类型,一般可分为二种: 1.标准主轴箱:组合机床上通常采用的类型,其主要特点是:籍助导向套进行鑽削、鑛孔、铰孔或籍助浮动夹头进行镗削工作。标准主轮箱的设计、制造及装配,基本上是采用标准和通用的零件及部件。如齿轮、主轴、中间轴、套、箱体及润滑部件等, 2.专用主轴箱:通常是由专用零件设计而成,当需要刀具没有导向工作时(例如:镗发动机汽缸体等),在一般情况下可采用专用主轴箱。     

主轴传动部件的热平衡技术研究与应用

分析主轴箱的主要热源以及发热量对整个主轴箱部组精度的影响,采用大流量的恒温油对主轴箱进行冷却与润滑以及优化主轴轴承安装工艺,以保证主轴高速运行的过程中其轴向变形量达到最小。通过试验验证,主轴达到热平衡时其伸长量为0.035 mm。通过对温升与热伸长量的函数进行研究,对轴向热变形进行补偿,以保证机机床在达到热平衡过程中,对工件加工精度的影响最小。     

一种高精度组合镗床的设计

本文阐述了为了提高普通镗削组合机床的加工精度,开发一种高精度组合镗床传动结构、主轴部件设计、主轴箱设计及有关通用部件的合理选择。图10幅。     

加工中心主轴热误差的分析与建模

在测量加工中心主轴系统的温度场和热误差数据的基础上,研究了温度变化与主轴热误差之间的关系,并用主成分分析法建立了两者的多元线性回归模型.经计算分析,该模型具有较高的精度,可以满足加工中心热误差实时补偿的应用要求,同时也可作为机床设计和制造的参考依据.     

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.     

液体静压主轴热特性分析与试验研究

有效的热变形仿真分析是机床热平衡设计以及热误差补偿的基础。为了提高热变形仿真的精度,通过优化发热量等计算方法以及合理设计分析流程,基于ANSYS Workbench对超硬车数控车床液体静压主轴箱系统进行热特性仿真分析以及温升测试试验。热特性仿真与测试试验结果表明:温度场仿真与试验结果误差在5%以内,保证了热变形仿真的有效性。由变形仿真分析知:主轴3个方向上的热变形及主轴前端最大变形为5μm,为热误差补偿提供理论基础。由试验结果得到了同一转速下各热源处温升随时间的变化曲线,为合理预热、提高加工精度提供理论基础。     

组合机床多轴攻丝主轴箱的设计

一、攻丝主轴箱概述: 攻丝主轴箱是用来佈置主轴和减速齿轮以及其他的一些相应机构的。它通过攻丝主轴把动力直接传递给丝维,从而在事先鑽出的孔上进行攻丝。 目前常见的攻丝主轴箱大体说来可归纳分成以下三种: 第一种是攻丝主轴箱本身无主进给运动的。这种主轴箱多是直接同机床床身或支柱把紧在一起。在攻丝的时候,主轴上作廻转运动,其廻转运动由直接把紧在主轴箱上的电机来完成或采用攻丝床身,经皮带传动使主轴廻转。这时,主轴本身没有轴向进给运动,也就是说整个主轴箱对机床其他部分来说没有相对位移。丝锥的进给由固定在攻丝模板上的靠模螺母来实现。电机接通以后,靠模桿一方面通过双键滑动连接把主轴的廻     

国外转塔主轴箱和自动更换主轴箱 组合机床的发展和现状

转塔主轴箱和自动更换主轴箱组合机床,近几年来在西欧的一些国家里得到了较大的发展。转塔主轴箱组合机床及手动更换主轴箱组合机床,早在五十年代就在一些工厂的小批或中批生产中应用过,得到很高的加工精度和良好的技术经济效果,但并没有引起更多人的注意,也没有得到进一步的发展。六十年代初期带数控和自动更换刀具的钻镗床即所谓的“机械加工中心”式机床出现以后,人们把实现单件或小批生产中孔加工     

龙门铣镗加工中心GMB250主轴箱热分析及优化

在精密加工过程中,机床基础大件的热变形会引起加工误差,影响加工精度。为了降低主轴箱热变形对机床精度的影响,以龙门式铣镗加工中心GMB250主轴箱为研究对象,基于Hypermesh与Ansys Workbench为软件平台,建立主轴箱热力学模型,计算其达到热平衡状态所需时间及温度场分布,采用热-结构耦合方法,分析稳态情况下不同热源对主轴箱热变形影响,通过调整热源位置及热源温度改善主轴箱热特性,提高加工精度。     

Design optimization and development of CNC lathe headstock to minimize thermal deformation

This paper has investigated an approach to reduce and compensate thermal displacement for high accuracy NC lathes. An efficient design and optimization method is proposed for a headstock structure design of NC lathes to minimize the thermal displacement of the spindle center position. Compared to the existing empirical methods, this method saves development time and cost. The Taguchi method and FEA method are used to identify the optimal headstock structure. The proposed method is verified by evaluating the spindle center transition of the headstock according to the optimization results.     

立式加工中心主轴系统热变形试验及误差补偿

立式加工中心经过长时间的运行之后,主轴箱及主轴系统组成的单元会产生热变形,这影响到被加工零件轴向尺寸的加工精度。以VMC750立式加工中心为试验对象,测量主轴箱多点温度及主轴变形伸长量,确定主轴变形的主要原因,建立误差补偿模型,通过对立式加工中心加工过程中的热误差进行了实时补偿实验,结果表明：通过热变形补偿,主轴系统热变形实测为0.28～0.33 mm,其误差可减少75％左右,验证了该模型的有效性。     

Prediction of thermo-elastic behavior in a spindle–bearing system considering bearing surroundings

This paper presents a simulation method based on system dynamics to establish a comprehensive prediction model for the thermal and mechanical behavior of a spindle–bearing system in consideration of bearing surroundings such as assembly tolerance, geometric dimension, cooling conditions, operating conditions and thermal deformation. By introducing a lumped element into the system, not only mechanical properties but also thermal behaviors can be readily examined and predicted. The most important behavior in the spindle–bearing system is the bearing pressure, which determines the spindle characteristics and friction moment. In this study three different simplified assemblies are investigated. One is the bearing inner race–shaft subassembly that includes a negative assembly clearance, and another is the outer race–housing assembly that includes a positive assembly clearance. The third is the entire system that is composed of a rolling element bearing, an inner race–shaft subassembly and an outer race subassembly. The two subassemblies are coupled by rolling elements in which the frictional moment and heat generation vary with the assembly clearance and thermal deformation of the bearing surroundings. The new method can be applied to spindle cooling as well as the optimal thermal and mechanical design of the spindle–bearing system for various surrounding conditions. Furthermore, on the basis of the proposed model, the effect of steel and ceramic bearing materials on the thermo-elastic behavior of the spindle system was investigated.     

基于有限元的140 kN摩擦焊机主轴箱响应面优化分析

以140 kN连续驱动摩擦焊机主轴箱为研究对象,应用有限元分析软件对主轴箱进行了静、动态相关特性的分析。为提高主轴箱综合力学性能,并实现主轴箱箱体材料的合理利用,以箱体壁厚等7个结构参数为设计变量进行了中心复合实验设计。根据得到的数据结果,基于Kriging插值法建立了主轴箱的响应面模型,并对各设计变量进行了灵敏度分析。利用多目标遗传算法完成了主轴箱的优化设计,与原结构方案相比主轴箱箱体减重16.6%,实现了焊机轻量化设计。经过对主轴箱响应面模型拟合精度的校验,验证了CCD实验法与Kriging插值法相结合可高效精准地完成主轴箱响应面模型的建立。因此这一优化方法同样适用于其他类型的机床零部件的设计。     

Analysis of thermal errors in a high-speed micro-milling spindle

Thermally induced errors account for the majority of fabrication accuracy loss in an uncompensated machine tool. This issue is particularly relevant in the micro-machining arena due to the comparable size of thermal errors and the characteristic dimensions of the parts under fabrication. A spindle of a micro-milling machine tool is one of the main sources of thermal errors. Other sources of thermal errors include drive elements like linear motors and bearings, the machining process itself and external thermal influences such as variation in ambient temperature. The basic strategy for alleviating the magnitude of these thermal errors can be achieved by thermal desensitization, control and compensation within the machine tool.This paper describes a spindle growth compensation scheme that aims towards reducing its thermally-induced machining errors. The implementation of this scheme is simple in nature and it can be easily and quickly executed in an industrial environment with minimal investment of manpower and component modifications.Initially a finite element analysis (FEA) is conducted on the spindle assembly. This FEA correlates the temperature rise, due to heating from the spindle bearings and the motor, to the resulting structural deformation. Additionally, the structural deformation of the spindle along with temperature change at its various critical points is experimentally obtained by a system of thermocouples and capacitance gages.The experimental values of the temperature changes and the structural deformation of the spindle qualitatively agree well with the results obtained by FEA. Consequently, a thermal displacement model of the high-speed micro-milling spindle is formulated from the previously obtained experimental results that effectively predict the spindle displacement under varying spindle speeds. The implementation of this model in the machine tool under investigation is expected to reduce its thermally induced spindle displacement by 80%, from 6 microns to less than 1 micron in a randomly generated test with varying spindle speeds.     

车削中心主轴系统热特性有限元分析的研究

以精密车削中心主轴系统为研究对象,将有限元技术应用于其主轴系统的热特性研究,在机床热分析理论基础上,计算了液体动静压轴承内外壁的温度和主轴箱体的温度,建立并分析了主轴系统的稳态温度场和主轴的变形情况,为系统热补偿提供了理论依据.     

Hybrid Model of High Speed Machining Centre Headstock

A hybrid high-speed machining centre headstock model based on two computation methods: the finite element method and the finite difference method is presented. The model allows one to calculate precisely the headstock's indices on the basis of which its optimal operating characteristics can be determined. The presented modelling methods allow one to evaluate a design from thermal, stiffness and durability points of view. By way of illustration, the behaviour of three machining centre headstocks with: an electrospindle on rolling bearings, a conventional spindle and an electrospindle on aerostatic bearings are modelled using the hybrid model.     

龙门式机床主轴箱热刚度研究

龙门式机床主轴箱的热伸长会影响工件的加工精度。分析主轴箱的热刚度机制，运用RBF神经网络的方法建立温升和位移的关系模型。通过测量主轴箱关键点的温度预测该点在下一时刻的温度变化量，进而得出主轴箱热刚度的变化规律。通过对比热刚度的预测值和测量值验证了该建模方法的有效性。     

机床热变形及热误差优化研究

为减少热变形对精密加工精度影响,对夏冬两季节机床主轴箱上温升和热变形及环境温度的影响进行了测试分析,并采用BP神经网络模型化的Volterra级数非线性系统实现热误差建模。分析结果表明：夏天环境温度受主轴箱散热影响而温度迅速升高;冬季机床散热较快,主轴箱上温升比较明显,环境温度几乎不变;同一台机床在夏季和冬季的热变形规律相似而变形量稍有不同。通过实验验证了该模型具有预测精度高的优点,为数控机床热误差实时补偿提供了参考。     

Geometrical accuracy of spindles of metal-cutting machines

The design of a spindle assembly of a metal-cutting machine has been analysed. The manufacturing and assembly errors of the assembly parts and their influence on the geometrical accuracy have been defined. Analytical relationships for the prediction of the spindle assembly geometrical accuracy at the stage of design have been proposed.