高速直线进给单元设计

对直线进给单元的基本类型和直线电机的结构布局进行了分析,研究了高速直线进给单元的基本结构,并运用有限元法对进给单元工作台设计进行校验,证明研制的高速直线进给单元能较好地满足设计要求。与传统的直线进给系统相比,ＧＤ－３型直线进给系统的速度和加速度能提高５－８倍。     

磁悬浮直线进给单元支承立柱设计及定位分析

针对机床用磁悬浮直线进给单元设计过程中的磁悬浮支承问题,比较了两种磁悬浮工作原理,确定了单自由度吸力型磁悬浮支承模型,并推广到五自由度磁悬浮直线进给单元模型的建立。运用SolidWorks三维软件设计了两种磁悬浮直线进给单元支承立柱,并运用ANSYS有限元软件对其进行定位分析,计算出了两种平台的支承立柱在进给方向和导向方向的最佳位置。所做的计算与分析可用于机床用磁悬浮直线进给单元结构的优化设计。     

直接驱动型磁悬浮直线进给单元

介绍一种机床功能部件——直接驱动型磁悬浮直线进给单元的原理与特点,该功能部件由直线电动机提供驱动力,由磁悬浮导轨导向和承载工作台,可满足数控机床高速化、精密化要求。并简述其研究现状和分析其关键技术问题。     

直线电机工作台垂直刚度的有限元分析

直线电机进给单元是高速数控机床的一种新型进给系统。其进给运动是由安装在工作台和床身之间的直线电机直接驱动实现的,具有进给速度高、加速度大、响应速度快、定位精度高等特点,由于工作台垂直方向除了切削负荷和自重以外,还要承受巨大的电磁吸力,而直线电视初级和次级之间的垂直间隙极小,故工作台的垂直刚度就特别重要。本文用有限元法对高速机床工作台的垂直刚度进行了分析研究,同时结合研究工作,还介绍了有关有限元三维     

高速机床中直线进给系统控制策略综述

介绍了直线电动机在高速机床伺服进给中的应用，分析了直线电动机用于进给驱动的特点。着重概括了在不确定因素影响下，闭环伺服进给驱动系统抑制扰动、提高稳态精度、加快动态响应以及增强鲁棒性的控制策略。包括滑模变结构控制、鲁棒控制、智能控制、和自抗扰控制策略等。最后根据各控制策略的特点提出了相应的改进方法。     

直线电机机伺服进给系统及其关键技术问题

介绍了直线电机的发展历程以及在高速精密机床上应用直线电机伺服进给系统的进展情况,讨论了直线电机伺服进给系统的一些关键技术问题。     

高速机床进给系统的发展趋势

在明确了高速加工对机床进给进给系统要求的基础上，比较和分析了滚珠丝杠、直线电机和并联虚拟轴机构等三种高速进给系统的性能、特点、存在问题及其解决办法，指出了它们各自的适用范围和应用前景。     

一种高速加工平滑运动轨迹自适应算法

提出一种基于多项式曲线的机床运动轨迹自适应控制算法.该算法克服了直线、指数、三角函数和S曲线加减速方法的不足,能够保证机床在高速运行过程中速度、加速度和加加速度均连续有界,运动平滑,避免冲击和震动;给出了在进给电动机额定转矩、额定转速、系统加速度和机床路径曲率约束下,核算机床最高允许进给速度的方法;提出了根据机床行程大小按运行时间最短确定机床运行方式的速度变迁控制策略.该自适应算法简单实用,可用于高速加工系统及CAM软件开发中.     

直线电机高速进给系统性能优化研究

高速切削技术越来越引起人们的关注。实现高速切削的关键技术之一,是开发具有高速能力的高性能数控机床。机床主轴的转速近年来有很大的提高,而机床进给系统大我仍采用滚珠丝杆传动的方式,使机床的最大进给速度受到限制,阻碍了机床高速性能的进一步发挥。本文介绍了一种采用直线电机直接驱动的机床高速进给系统。采用非线性系统稳定性分析的方法确定系统的参数,并对伺服系统性能进行实验研究。实验证明,用这种方法优化该类系统     

直线电机进给驱动技术在数控机床上的应用

简述了直线电机工作原理及其驱动技术,并且举例说明了直线电机直接驱动与传统数控机床"旋转伺服电机+滚珠丝杠"的传动方式对比具有的巨大优势.介绍了直线电机进给驱动技术在数控机床上的几个应用实例,指出直线电机进给驱动技术将是高速数控机床未来发展的方向.     

直线电机进给系统摩擦自适应补偿控制

为消除非线性摩擦干扰对直线电机进给系统定位精度的不利影响,提出一种基于LuGre摩擦模型的自适应补偿控制方法。建立直线电机进给系统的动力学方程,并在系统建模中引入基于自适应因子的改进LuGre模型;采用反步设计法的思想,利用李雅普诺夫第二法推导了自适应控制律;最后进行了半物理仿真实验。仿真结果表明:该自适应控制器应用于直线电机进给系统的摩擦补偿是可行的,有效提高了系统的位移定位精度和速度跟踪精度。     

环境温度对微进给平台定位精度影响规律的研究

微进给机构是超精密加工设备中实现精密定位的重要组成部分，加工环境条件极其微小的变化均可能影响其定位精度。文章运用I-DEAS软件，针对自行研制的一台精密磨削用多自由度辅助微进给平台，在假定其它加工环境均满足加工要求的前提下，对不同环境温度下其热变形情况进行了初步的研究。研究发现，微进给平台沿z向的最大变形量与环境温度呈正比；环境温度对微进给平台z向最大变形量的影响与微进给平台的动平台上表面温度值的大小呈正比。     

轴对称非球面加工进给速度控制技术研究

本文根据轴对称非球面的加工误差特性，通过分析轴对称非球面磨削加工中砂轮磨削线速度、进给速度对加工精度影响的条件，提出控制砂轮进给速度使轴对称非球面工件各点磨削量均匀的方法。该技术避免了传统加工方法中原理上固有的磨削量差异缺陷，提高了系统的加工精度。研究结果表明：进给速度控制方法针对轴对称非球面加工中常用的平面砂轮、圆弧砂轮、球面砂轮，均得到了良好的控制效果；采用新方法的数学模型更接近于理论计算轨迹，可以进一步提高工件的加工精度；新方法进给速度由外沿加工至中心部分，进给速度逐渐加快；并且变化率也逐渐增大。     

Servo design of a vertical axis drive using dual linear motors for high speed electric discharge machining

This paper proposes a synchronous control scheme for a linear servo system applied to the vertical axis drive of a die-sinking electric discharge machine (EDM) tool. The investigated vertical axis drive is constructed with dual parallel linear motors, which are arranged to jointly drive the feed axis for improvement of the overall thrust and structural stiffness. A pneumatic cylinder is employed to compensate the gravitational effect of the feed axis with its electrode and holder. A mechanical coupling is designed to firmly bridge the two linear motors and carry the feed axis. Therefore, synchronous control for the motors is critical for not only position accuracy, but also machine safety. Moreover, by controlling the thrust outputs and positions of the motors to be as equal as possible, the potential “pull and drag” effect between the motors can be reduced and loads can also be equally shared. The proposed “position/thrust hybrid synchronous control” scheme is applied to the EDM to achieve high-speed, accurate machining, and the experimental results show that the synchronization error between the two parallel motors and the positioning accuracy are both satisfactory when operated under high-speed conditions.     

基于多传感器融合的移动机器人定位研究

针对室内未知环境下单一传感器定位累积误差大、受环境局限等缺点,设计一种多传感器非线性融合定位系统,以提高移动机器人自主导航的定位精度。该系统通过高斯牛顿方程对由激光雷达、惯性测量单元、轮式里程计测量得到的位姿信息进行融合优化,补偿由于在室内环境信息下单一传感器定位精度低所带来的定位误差。实验结果表明:应用多传感器融合定位系统的移动机器人在长6 m、宽3 m的室内面对曲折复杂的路径和各种噪声干扰时运行总路程12.8 m后,可以将定位误差稳定在0.106 3 m内,并将平均相对误差稳定在0.716%左右。与现有方法对比,使用该方法提高了室内移动机器人定位的精度和鲁棒性。     

Compensation of Axial Vibrations in Ball Screw Drives

This paper presents a precision control strategy for ball screw drives. Axial vibrations are modeled and actively compensated in the control law, which enables the realization of high positioning bandwidth. Lead errors, arising from imperfections of the screw, are modeled and removed from the loop by offsetting their effect from the command trajectory and position feedback signals. Effectiveness of the proposed strategy is demonstrated in high speed tracking experiments conducted on a ball screw drive, where a linear positioning accuracy of 2.6 um has been maintained while traversing the axis at 1000 mm/s feed with 0.5 g acceleration.     

Thermal error analysis for a CNC lathe feed drive system

The development of high-speed feed drive systems has been a major issue in the machine tool industry for the past few decades. The resulting reduction in the time needed for tool changes and the rapid travel time can enhance productivity. However, a high-speed feed drive system naturally generates more heat and resultant thermal expansion, which adversely affects the accuracy of machined parts. This paper divides the feed drive system into two parts: the ball screw and the guide way. The thermal behavior model for each part is developed separately, in order to estimate the position errors of the feed drive system caused by thermal expansion. The modified lumped capacitance method (MLCM) and genius education algorithm (GEA) are used to analyse the linear positioning error of the ball screw. Thermal deformation of the guide way affects straightness and introduces angular errors, as well as affecting linear positioning. The finite element method is used to estimate the thermal behavior of the guide way. The effectiveness of the proposed models is verified through experiments using a laser interferometer.     

Thermal modelling of an HSC machining centre to predict thermal error of the feed system

Machine tools equipped with linear motors can achieve high feed speed as well as high accuracy. However, the direct feed drive system generates heat through power loss and friction. In combination with environmental influences such as machine shop climate, this can lead to a local deformation of the machine tool structure and induce a direct positioning error. This paper presents a thermal model, using the finite element method, to simulate the thermal behaviour of a high-speed cutting machining centre equipped with linear motors. This model considers the complex boundary conditions such as heat sources, contact and convective heat transfer. Transient changes in temperatures and deformations are allowed in the solution. The comparison of the experiments show that this model can predict the temperature distribution and positioning error under specified operating conditions very well.