基于西门子功能模块的伺服定位系统的研究

为提高某数控工作台的定位精度,以多数现代数控机床所采用的半闭环控制系统为研究对象,提出了一种基于西门子FM351定位模块的全闭环伺服定位控制系统.通过引入直接检测运动部件最终位移的数字测量环的方法,利用光电编码器检测旋转工作台的角位移,经反馈信号控制伺服驱动器,完成对交流伺服电机的转速控制,进而实现了对工作台的精确定位.并在低速大惯量转台上对本伺服定位系统进行了实验验证,实验结果表明该方法有效的消除了机械传动产生的误差对定位精度的影响,显示了全闭环伺服定位控制系统的优越性.     

Robust compensation of elastic deformations in ball screw drives

Elastic deformations occur in ball screw drives typically due to inertial forces, guideway friction, and cutting forces. This results in elongation and compression of the ball screw, which deteriorates the dynamic linear positioning accuracy. Closing the control loop with a linear encoder helps to alleviate this problem to a certain extent. However, linear scales cost significantly more than rotary encoders and their installation also brings about additional costs. This paper presents a new strategy for mitigating the detrimental effect of elastic deformations, in order to improve the translational accuracy of ball screw drives when only rotational feedback is available. A simple and physically intuitive model is developed, which is used to offset the position commands that are fed to the servo control law. Compensation is proposed using a closed-loop scheme, which is found to be robust against cutting forces, as well as variations in the table mass and guideway friction. These effects are detected as equivalent disturbances that cause an elastic deformation. The proposed closed-loop compensation strategy has been validated in machining and high-speed tracking experiments, as well as simulations, which demonstrate its effectiveness in terms of improving the ball screw drive’s final translational accuracy.     

空心滚珠丝杠在数控机床伺服进给系统中的应用

针对数控机床主轴和伺服传动系统的热误差阻碍进一步提高机床定位精度的问题,对数控机床伺服进给系统的热变形作了深入研究。结果表明:螺母摩擦和轴承摩擦是滚珠丝杠伺服进给系统的主要热源,其摩擦热量与滚珠丝杠转速及轴向载荷几乎成正比;采用空心丝杠和空心螺母有效抑制了滚珠丝杠在高速进给时的热变形量,减小伺服进给系统的稳态误差。     

滚珠丝杠副轴向静刚度试验系统开发

设计开发了滚珠丝杠副轴向静刚度测试系统,包括液压加载控制系统、螺母副微位移测试系统。设计了以测力传感器输出信号为基准的刚度检测方案。按照标准测试试验流程,通过RS-232通信接口实现了对滚珠丝杠副轴向静刚度的测试和曲线的实时显示。为滚珠丝杠副轴向静刚度的深入研究,进一步提高滚珠丝杠副的定位精度提供了技术方法及试验平台。     

超精密滚珠丝杠进给系统的谐响应分析

超精密滚珠丝杠进给系统除了在工作台轴向存在外界激励,电机在启动和刹车时产生的冲击以及电机轴输出端的振荡特性都可能导致整个进给系统产生振荡,而利用目前的滚珠丝杠进给系统有限元模型不能准确地分析出电机轴输出端的转矩动载荷对进给系统产生的谐响应。针对此问题,提出一种新的进给系统有限元模型,保证了其谐响应分析的准确性。     

Integrated autonomous monitoring of ball screw drives

In ball screw drives wear occurs which results in decreasing dynamic performance and accuracy and can finally lead to machine breakdown. In order to avoid unacceptable machining results and failures, ball screws are changed based on previously calculated motion cycles and loads. State dependent maintenance requires monitoring of the wear progress. Here, an integrated sensory ball screw double nut system is presented. It measures the pre-stress as a wear indicator by strain gauges or sensory thin layers. Sensor information is processed by integrated electronics and communicated wirelessly. Energy harvesting and hybrid energy supply strategies are introduced. Measurement results are discussed.     

数控车床过大的反向间隙故障维修

过大的反向间隙严重影响数控车床的加工精度。根据加工路线分析出数控车床加工精度超差的原因是X轴的反向间隙过大,再对反向间隙过大和电机负载过大两个原因进行故障排查,发现刀架和丝杆的机械形变是反向间隙过大和电机负载过大的根本原因。分析了加工精度超差的真正原因,详细阐述维修过程及方法,并提出一些维修和加工建议。     

Radial error measuring device based on auto-collimation for miniature ultra-high-speed spindles

This study has developed a radial error measuring device for miniature ultra-high-speed spindles because it is very difficult to measure the radial error motion of miniature ultra-high-speed spindles by the conventional measurement method using capacitive-type displacement sensors. The authors have proposed an optical measurement method based on auto-collimation, which evaluates the radial error motion according to the movements of a laser beam reflected from a target sphere attached to the spindle end. This optical measurement method is suitable for radial error measurements of miniature ultra-high-speed spindles because of its applicability to a small target sphere, high-speed response and minor susceptibility to electric noise. In this paper, the measurement principle, and basic characteristics of the optical measurement method in addition to an approximate analysis are shown. The radial error motion of a miniature ultra-high-speed spindle with a steel ball 1 mm in diameter are measured by an optical measuring device designed and manufactured to implement the proposed method. The measurement results show that the optical measuring device is able to measure the radial error motion of ultra-high-speed spindles with a maximum rotational speed of 200 krpm.     

DK9032数控外圆电熔爆磨削复合机床伺服进给系统设计

介绍了DK9032数控外圆电熔爆磨削复合机床伺服进给机构及其滚珠丝杠副、伺服电机、丝杠轴承的选择计算,并对伺服进给系统的综合刚度和传动精度进行了验算.经实际生产验证,该伺服进给系统能准确地实现伺服运动,满足加工过程要求的系统定位精度、响应速度及稳定性.     

电动冲床连杆式滚珠丝杠副动力源的设计

通过对电动冲床的研究,设计了一种全新的连杆式滚珠丝杠副动力源。该动力源采用伺服电机带动滚珠丝杠旋转,使丝杠螺母上下移动,进而带动经特殊设计的三铰接连杆,无需采用控制程序就能具备空载快进、快退,负载慢进的功能。测试结果显示,在不增加驱动电机功率、扭矩,不增大滚珠丝杠副受力的情况下,能使冲切力增大4倍多。     

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。     

含虚拟材料结合部的高速滚珠丝杠进给系统动态特性分析

为了构建精确的滚珠丝杠进给系统结合部虚拟材料模型,提出基于多目标优化方法获取结合部虚拟材料模型参数的方法。采用分形理论建立滚珠丝杠进给系统结合部虚拟材料参数解析模型,得到结合部虚拟材料参数的初步优化区间。基于多目标优化方法,获得滚珠丝杠进给系统结合部虚拟材料模型的参数,并通过试验对此参数获取方法进行了验证。分析结果表明:滚珠丝杠进给系统的振动模态会随工作台位置的变化而改变,主要因为工作台位置变化会改变伺服电机输出轴和工作台之间丝杠的长度,从而影响系统的刚度。     

On-machine measurement of location errors on five-axis machine tools by machining tests and a laser displacement sensor

This paper proposes an on-machine measurement (OMM) of all location errors on five-axis machine tools. Five machining patterns are successively performed on a cubic workpiece. The basic idea is to use a set of large rotations of rotary axes to prolong the moving distance of linear axes when squareness errors of linear axes are identified. Then, a set of small rotations of rotary axes are used to decouple the squareness errors of linear and rotary axes. Based on this, the long and deep slots in previous machining tests are improved to be a set of short and shallow ones. These miniaturized slots reduce the material removal and minimize the influence of cutting force and thermal deformation on the measuring results. Then the cutting tool is substituted by a laser displacement sensor (LDS) to measure the mismatch between the finished surfaces of the corresponding slots. All the measured surfaces are located on the bottom of the slots to fit the LDS characteristic of one dimensional measurement. Three gestures of the rotary table and tilting head are used to implement the single-setup OMM and the influence of location errors on the measuring results is compensated. Validation of the identified values is also provided by a set of simple tests using different measuring instruments. The efficiency and accuracy of location errors measurement method on five-axis machine tools are improved.     

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。     

基于复合直梁型柔性铰链的导轨直线度测量研究

刚度是影响柔性铰链机械性能的重要参数指标,建立复合型柔性铰链拉伸刚度模型,在不同参数、不同尺寸条件下计算其解析解,通过ANSYS Workbench对其进行静力学仿真,分析各个结构参数对其刚度的影响,同时得出该种复合柔性铰链在同等尺寸及力的作用下比传统双边平行铰链有较大的输出位移。在解析解与仿真结果误差较小的情况下,设计出一种参数最优化的复合柔性铰链并搭建了测量平台,对滚珠丝杆驱动的导轨进行了直线度误差测量,将其结果和激光干涉仪测量结果对比,验证了基于该柔性铰链搭建的测量平台满足直线度的测量需求。     

基于FPGA技术消除光电编码器抖动干扰的设计

光电编码器是常用于检测车床主轴系统的转速和角位移,也经常在伺服系统中用于检测伺服电机的转速.机械振动会不可避免地导致其主码盘的振动,从而引起输出波形的畸变,引起计数错误,使伺服驱动系统不能正常运行,影响机床的加工精度和定位精度.本文针对减少光电编码器计数误差的问题,提出了利用FPGA技术可以有效地消除抖动和干扰的方法.通过实际运行证明,该方法具有灵活、可靠优点.     

FPGA在增量式光电编码器测角系统中的应用设计

为了获取无刷直流电动机驱动控制系统中转子位置信息,应用FPGA对增量式光电编码器的转子位置信息进行数字化处理,设计并实现相应的位置检测方案.提出了一种基于FPGA实现的增量式光电编码器测角方案,给出了由FPGA实现的DDS方式查找表与增量式光电编码器无绝对零位的自启动方案.仿真和实验结果验证了方案的可行性.该设计可用于小卫星飞轮驱动电机测角系统,改进了系统精度和性能;同时可与其它功能模块或IP核组合用于其它驱动系统.     

金属粉末3D打印机的机械结构设计

为了降低工业成本和提高零件机械性能,将金属粉末注射成型技术和快速成型技术相结合,提出了金属粉末挤出堆积快速成型工艺,工艺装备的机械结构由三维快速成型平台和单螺杆挤出装置两部分组成。三维快速成型平台采用伺服电机驱动高精度威远滚珠丝杆副、HIWIN直线导轨副结构,单螺杆挤出装置由大功率伺服电机驱动螺杆转动,采用ABLE减速机增大螺杆转动所需扭矩。     

Analysis of a model to forecast thermal deformation of ball screw feed drive systems

In machine tools with semi-closed loop numerical control, the thermal deformation of the ball screw directly produces the position error of the feed drive system. In this work the method of multiple regression is used to analyze the thermal deformation of a ball screw feed drive system. Key points of thermal source (front bearing, nut and back bearing) were selected as independent variables of the analysis model. The test results show that this method can well predict the thermal deformation of the ball screw during variation of the speed of rotation.     

Periodic variation of preloading in ball screws

The preloading is a main characteristic for the functionality of a ball screw. The path of preloading during operation with no thrust load is an indicator for the actual inner forces, the friction produced by the ball screw and finally for the quality of the unit. Due to manufacturing tolerances the preloading over the useful travel of the ball screw differs from its specified value. However, not only the overall loading of a ball screw varies, but also the local load distribution within the nut. This is expressed by a periodic variation of the internal forces which has an effect on the alignment of the nut and therefore on the uniformity and the motion characteristics of a ball screw feed drive. The following paper deals with the occurrence of these periodic force variations and offers an explanation for this particular phenomenon.