关于逆向车削加工细长轴误差的力学分析

针对细长轴车削加工，分别在两种不同装夹条件下(一端卡盘夹紧、一端顶尖支承和两端顶尖支承)进行正向切削和逆向切削时的工件变形进行了力学分析，建立了正逆向切削工件在切削力作用下产生弯曲变形的解析模型。具体算例表明：逆向切削时工件的弯曲变形以及由此引起的加工误差远小于同等条件下正向切削的变形和误差。该模型及分析结果可用于细长轴加工的工艺设计。     

精密测量对细长工件支承点位置的要求

<正> 精密测量长丝杠、长刻度尺、长量块等细长等截面直杆件时,为了将自重引起的变形限制在最小范围内,对支承点的布置必须提出严密的要求。本文对这些要求以及形成它们的数学力学分析作系统的介绍。假设工件的纵向对称平面被置于铅垂位置,工件中性层与纵向对称平面的交线为工件的轴线。 1.要求自重对工件轴线直线度误差影响最小,则两支承点离轴线长度中点距离必须为0.2769L。分析与证明如图1所示,将座标原点O置于工件轴线长度中点。设左右两支承点对称于Y轴,它们离该轴距离为x,工件长度为L,由工件自重     

轴向拉夹车削细长轴

目前在车床上车削细长轴时,采用一端卡盘、一端顶尖或两端顶尖支承的定位装夹方式。图1、图2为这两种定位装夹的示意图和力学模型,因工件受到轴向顶压力,而称轴向压夹法。细长轴车削采用这种装夹时,受轴向顶压力和自重影响而弯曲,特别是在高速旋转时,受到离心力的作用而使弯曲更加严重,振动也会相应加剧。并且在切削热的作用下,轴向膨胀伸长也会加剧细长轴弯曲。     

细长轴车削加工误差的分析

针对细长轴的车削加工。分别对在一端卡盘夹紧、一端顶尖支承及两端顶尖支承的装夹条件下车削加工时的变形进行力学分析。建立在切削力作用下产生弯曲变形的解析模型。算侧表明：逆向车削时轴的弯曲变形以及加工误差远小于同等条件下正向车削的变形和误差。     

细长丝杠加工方法的改进

当丝杠的螺纹大径与其长度之比为 1∶30及其以上时 ,称为细长丝杠。由于细长丝杠的刚性差 ,在切削力作用下 ,工件容易产生弯曲变形和振动 ,导致常规方法加工难以达到设计要求 ,甚至造成大量报废。为了克服这些问题 ,我们采取了以下措施加以改进。(1)改进跟刀架　我们将两爪结构跟刀架改进成如图 1所示结构。即改为三爪 ,并且底部的卡爪用弹簧支承 ,工件在车削中由三只卡爪和车刀共同抵住 ,使得工件上下、左右都不能移动 ,从而不致产生振动。另外 ,将卡爪前端的形状由小曲面改为宽圆弧 ,大大增加了支承卡爪与工件的接触面积。其材料选用铸铁…     

精密测量细长工件支承点位置的确定

精密测量长丝杆、长刻度量具、长量块等细长等截面直杆时,为了使由自重引起的变形被限制在最小范围内,对支承点的布置必须严格要求.本文对这些要求的合理条件进行了力学分析。假设工件的纵向对称平面被置于铅垂位置,工件中性层与纵向对称平面的交线为工件的轴线。要求自重对工件轴线直线度误差影响最     

机床超长丝杠的加工工艺

机床超长丝杠属于难加工类产品，在切削过程中，由于受切削力、自重和旋转时离心力的作用，会产生弯曲、振动现象，导致用常规方法加工难以达到设计要求，甚至造成大量报废。现针对机床超长丝杠的加工要求，根据实际经验，探索总结出一套切实可行的对接法加工超长丝杠的思路，并介绍了工艺过程。     

自定心中心架的力学分析与仿真

自定心中心架用于轴类工件尤其是丝杠、螺杆等工件机械加工时进行辅助支承,其夹持工件的定心精度直接影响零件本身的加工精度。为了实现中心架的参数化设计,以MATLAB、UG和ANSYS软件为平台,利用参数化设计方法和虚拟样机技术,在UG中建立中心架的参数化模型并将摆杆导入到ANSYS中进行有限元分析,为中心架结构拓扑优化奠定基础。     

高速逆向车削细长轴

本文对加工细长轴正向切削和逆向切削时的受力和变形进行了分析，建立了在切削力作用下发生弯曲变形的力学模型，并对机床——工件——刀具组成的工艺系统进行综合优化组合，得出高速逆向切削细长轴可以提高轴的刚性，减少其弯曲变形，保证轴的加工精度的结论。     

用车床尾座补偿热膨胀

车削长轴类工件时，为防止热膨胀使工件弯曲变形，常使用弹性回转顶尖支承工件进行加工。     

长跨距滚珠丝杠辅助支撑装置

介绍了一种数控机床长跨距滚珠丝杠使用的辅助支撑装置,该辅助支撑装置是一种可以与滚珠丝杠螺母一起随动的动态滚珠丝杠辅助支撑装置,它能有效解决长跨距滚珠丝杠自重下垂变形以及旋转抖动问题,延长了长跨距滚珠丝杠及其支撑轴承的使用寿命,提高了机床运动精度和加工精度,降低了机床运动噪声.     

The effect of dynamic behavior on surface roughness of ball screw under the grinding force

The dynamic behavior of a ball screw under a moving grinding force and the resulting ball screw surface roughness are investigated. The system includes a ball screw, a headstock, a tailstock, a steady rest, a grinding wheel, and a wheel head. Equations of motion of the system are derived through Lagrangian approach combined with global assumed mode method in this study. The transient responses of the system due to a moving force are evaluated using Runge?CKutta method. Results show that the steady rest can reduce 90% vibration in a grinding process. An equation is proposed to predict the maximum response by the cutting depth. Then we simulate the grain height distribution on the grinding wheel, considering transient response on the ball screw and the grinding wheel. Lastly, the ball screw surface roughness could be simulated via calculating the depth of all working grains. The purpose of using grinding process is that the ball screw needs fine surface roughness. The ball screw surface roughness is influenced by the grain size more than the structure numbers can be.     

滚珠丝杠副卡死现象原因分析

高效传动滚珠丝杠在装配完成后经常会出现卡死现象。一般情况下滚珠丝杠副生产厂家认为是丝杠与螺母间隙过大或不适当预紧造成的,但却一直未能做出合理的解释。本文通过理论分析说明了滚珠丝杠副卡死的机理和给出了造成丝杠副出现卡死的主要因素。     

基于Access数据库实现滚珠丝杠的一键式绘图

提出了一种简单方便绘制滚珠丝杠图纸的方法,即滚珠丝杠一键式绘图的方法,将滚珠丝杠的所有相关参数保存到A ccess数据库中,只需在A uto CAD VBA界面中输入丝杠编号即可调用数据以及Visual Lisp程序,将图纸准确地绘制出来,可以大大地提高设计人员的工作效率。     

Three-dimensional modeling for predicting the vibration modes of twin ball screw driving table

As a redundant drive mechanism, twin ball screw feed system has the advantage of high stiffness and little yaw vibration in the feeding process, while leads to increased difficulty with vibration characteristics analysis and structure optimization. Only low-dimensional structure and dynamics parameters are considered in the existing research, the complete and effective model for predicting the table＇s vibrations is lacked. A three-dimensional（3D） mechanical model of twin ball screw driving table is proposed. In order to predict the vibration modes of the table quantitatively, an analytical formulation following a comprehensive approach is developed, where the drive system is modeled as a lumped mass-spring system, and the Lagrangian method is used to obtain the table＇s independent and coupled axial, yaw, and pitch vibration modes. The frequency variation of each mode is studied for different heights of the center of gravity, nut positions and table masses by numerical simulations. Modal experiment is carried out on the Z-axis feed table of the horizontal machining center MCH63. The results show that for each mode, the error between the estimated and the measured frequencies is less than 13%. The independent and coupled vibration modes are in accordance with the experimental results, respectively The proposed work can serve a better understanding of the table＇s dynamics and be beneficial for optimizing the structure parameters of twin ball screw drive system in the design stage.     

高速精密滚珠丝杠副综合性能测试仪

为满足高档数控机床对滚珠丝杠副的高速、高精度、高刚度、高寿命、高可靠性等的要求,山东济宁博特公司研制开发了精密滚珠丝杠副综合性能试验台、高速精密滚珠丝杠副速度噪声试验台、精密滚珠丝杠副刚度试验台、精密滚珠丝杠副载荷试验台、精密滚珠丝杠副摩擦力矩测试仪等。利用这些试验装置可对滚珠丝杠副的加速度、速度、温升、热位移、噪声、定位精度及重复定位精度、静刚度、静载荷及动载荷、摩擦力矩等性能参数进行测试,为产品改进及用户提供准确可靠的检测数据。文章主要介绍测试仪器的部分性能。     

滚珠丝杠螺母副热态特性建模方法

以某外循环滚珠丝杠螺母副为研究对象,对其热态特性及其建模方法进行研究。在分析滚珠丝杠进给系统的热源和边界条件的基础上,建立了丝杠稳态温度分布的数学模型,并通过软件编程求解得到丝杠温度场和滚道的存在对丝杠稳态温度的影响;建立了考虑滚道影响的滚珠丝杠进给系统有限元分析模型,获得了滚珠丝杠进给系统稳态和瞬态热特性分析结果;最后通过滚珠丝杠螺母副热特性试验,获得了滚珠丝杠进给系统关键点的温度及其变化情况。研究结果表明：所建立的滚珠丝杠螺母副热特性分析数学模型可以较准确地获得滚珠丝杠的温度场,忽略滚道会使滚珠丝杠螺母副的温度场仿真结果产生15%～20%的误差。     

滚珠丝杠系统的热特性建模与分析研究

在研究国内外的滚珠丝杠现状的基础上,进行了滚珠丝杠系统的热特性建模与分析研究。利用Pro／E软件得到滚珠丝杠的CAD模型,并导入ANSYS有限元分析软件中,通过热分析与结构分析,获得高速滚珠丝杠的温度场,并在此基础上分析了滚珠丝杠的热变形及热应变,确定滚珠丝杠的热位移,从而为滚珠丝杠的优化设计提供了参考。     

滚珠丝杠副发展及研究现状

首先介绍了滚珠丝杠副的起源与发展,指出了其工作特点,然后对目前滚珠丝杠副各性能的研究现状进行了归纳,对滚珠丝杠副的发展及研究现状进行了总结,最后对滚珠丝杠副未来的发展趋势进行了综述和展望,为未来对滚珠丝杠副的研究提供参考.     

Experimental analysis and simulation of nonlinear microscopic behavior of ball screw mechanism for ultra-precision positioning

In this paper, microscopic behavior of a preloaded ball screw supported by ball bearings is discussed based on experimental results and simulation. An experimental apparatus is specially designed and constructed to independently measure the torques of ball screw, ball bearings supporting the screw shaft and driving motor. It is clarified experimentally that the nonlinear microscopic behavior of a positioning mechanism driven by a ball screw is affected not only by the ball screw itself, but also considerably by the ball bearings supporting the screw shaft. Moreover, the ball screw and the ball bearing have their own properties within the deferent limit of the elastic region, and their contribution ratios to the total apparent property of the mechanism change in a complicated manner according to the driving range. To demonstrate the elastic property, a simulation model for the nonlinear microscopic behavior is proposed using a viscous-elastic-plastic model, and procedure of identifying the model parameters is shown. The simulation results on micro-step positioning agree with the experimental results, and the availability of the simulation model proposed is verified. Moreover, the simulation model obtained is compared with previous analytical models of nonlinearity based on elliptic contact under torsion, and the advantage of the proposed model is demonstrated.