面向数控机床可靠性试验的多维力随动加载装置

面向五轴联动数控机床的可靠性试验提出多维力随动加载方法,对五轴联动进给主轴施加多维力载荷,形成复杂进给抗力,部分模拟主轴复杂切削力环境。基于6-PUS并联机构研制多维力随动加载装置,采用模糊PID控制器建立显式力控制系统,比例和积分增益可随加载误差自适应调节。在五轴联动数控机床上开展多维力随动加载实验,结果表明,加载装置能够跟随机床主轴的单轴、三轴联动和五轴联动进给运动,根据期望值对主轴施加三维力,加载误差小于3.2%,在机床执行多种加工轨迹时形成有效进给抗力,为后续引入动态加载模拟复杂切削力提供理论和装备支撑。研究成果可为数控机床可靠性试验提供低成本、可循环的加载方式,有利于测试的规模化和标准化发展,也可为精度保持性、超载试验、跑合试验等机床性能测试提供新的负载模拟思路。     

机床直线进给系统性能测试平台的测控系统设计

为了研究机床直线进给系统的性能,设计了一种测试平台。其控制系统包括电机驱动、随动加载电机控制和气动控制,测量系统包括传感器布局和测量软件开发。设计了控制电路和控制器,以控制被测进给单元和随动加载单元的同步直线进给运动;采用气压缸模拟切削力,对被测进给单元在三个方向上施加随动力;合理布局温度、位移、加速度、扭矩、光栅传感器,以实现对被测进给单元各项性能参数的测试;开发了测量软件,用于采集传感器信号和分析被测进给单元的性能参数。应用设计的测控系统,测试并分析了切削力对直线进给系统温升和热误差的影响。结果表明:所设计的测试平台及其测控系统可以用于测试机床直线进给系统的各项性能。     

数控机床主轴运转可靠性试验装置

介绍一种可以检验数控机床主轴运转可靠性的试验装置,该装置可对主轴进行模拟加载试验。     

五轴联动数控铣床双转台进给系统设计与仿真

在五轴联动数控机床加工过程中,加工点的切削速度与切削角度不规则地变化。为了获得加工过程的动态数据,利用三维造型设计软件(Creo Parametric)对五轴联动双转台进给系统进行设计、建模与运动仿真。通过Creo Parametric的仿真模块,模拟机床加工时进给系统的实时动态特性,获得刀具与工件之间的相对切削速度、动态铣削力矩、蜗杆所受最大轴向力等,验证了电机和关键轴承选型的正确性,使五轴联动双转台进给系统的可靠性大大提高。     

车削中心自动变位全载荷加载装置设计及试验研究

为了能够在数控机床刚度检测中更加准确地模拟刀具真实切削状态,提出了一种模拟全载荷加载检测方法。基于实际切削过程中刀具受到力和力矩的全载荷作用,切削位置发生变化的情况,根据实际切削中切削力比例分配原理,在对受力点和的受力方向坐标变换的基础上,设计了自动变位模拟全载荷加载装置,通过试验验证了加载装置各向力的比例关系,并将其应用在机床刚度分布检测试验中,得到了刀具在不同切削位置下,机床各测点的位移量,试验结果为评价和改进机床结构设计提高机床静刚度提供了数据依据,为研究和改进预测以及方案修改方法提供了试验手段。     

五轴机床机构运动精度的可靠性分析

五轴联动加工中心是数控机床的高端产品。运动精度是评价机构质量的重要考核指标。以往机床机构运动精度分析中,往往不考虑输入误差的随机性,造成评价结果不准确。应用齐次坐标变换,推导了一种2R3T型五轴机床的运动学方程。基于多体系统理论,建立了机床的误差模型。考虑输入误差的随机性,推导了机构运动精度可靠性计算模型。机床机构运动可靠性分析为提高机床加工精度和使用寿命提供了一定的理论参考意义。     

数控机床单轴受力误差测量系统

随着切削力的增大和高效切削以及一些难加工材料应用的日益广泛,切削力误差问题变得越来越突出.提出数控机床单轴受力误差测量系统,设计施力装置,模拟切削过程中工艺系统受力状态,直接获取机床误差数值.并运用此系统进行了机床单轴受力误差的测量实验,研究成果为数控机床单轴受力误差提供了理论基础和测量方法.     

五轴数控滚齿机切削力误差综合运动学建模

根据数控滚齿机运动的实际情况,分析了机床运动副的运动学原理,利用齐次坐标变换对一台包含3个移动轴和3个转动轴的四联动数控滚齿机建立了切削力误差综合数学模型.该分析方法可为其他类型的多轴数控机床误差综合建模及补偿提供理论参考.     

龙门五轴加工中心可靠性试验

针对龙门五轴加工中心的结构特点,提出其可靠性试验的总体试验流程及方法。归纳了龙门五轴加工中心可靠性试验几何精度、位置精度、运动参数、典型试件加工的评定方法。设计了X\Y\Z轴的加载试验、主轴的加载试验、空转加速试验。对某GMC2550型龙门五轴加工中心进行可靠性试验,利用试验数据计算其可靠性指标的平均故障间隔时间。     

加工中心主轴可靠性试验装置设计与应用

针对加工中心的关键部件主轴,对其可靠性试验的必要性进行了阐述,提出了一种快速加载的可靠性试验方法,并根据主轴的结构特点和可靠性试验的具体要求,实现了主轴可靠性试验装置的方案设计和详细设计。通过主轴可靠性试验装置的搭建,开展了主轴可靠性的相关加载试验,并将该试验结果与加工中心其他可靠性试验相结合,通过相应的数据分析软件,评定出机床的薄弱环节和可靠性量化指标。以便从设计、制造、使用和维护等各方面采取对策和措施指导主轴单元的可靠性设计,从而保证主轴设计和使用过程中的可靠性增长。     

Error modelling and measurement for the rotary table of five-axis machine tools

Rotary tables are widely used with multi-axis machine tools as a means for providing rotational motions for the cutting tools on the three-axis machine tools used for five-axis machining operations. In this paper, we present a comprehensive procedure for the calibration of the rotary table including: geometric error model; error compensation method for the CNC controller; error measurement method; and verification of the error model and compensation algorithm with experimental apparatus. The methods developed were verified by various experiments, showing the validity and effectiveness of the presented methods, indicating they can be used for multi-axis machine tools as a means of calibration and precision enhancement of the rotary table.     

MODELING AND COMPENSATION TECHNIQUE FOR THE GEOMETRIC ERRORS OF FIVE－AXIS CNC MACHINE TOOLS

One of the important trends in precision machining is the development of real-time error compensation technique. The error compensation for multi-axis CNC machine tools is very difficult and attractive. The modeling for the geometric error of five-axis CNC machine tools based on multi-body systems is proposed. And the key technique of the compensation-identifying geometric error parameters-is developed. The simulation of cutting workpiece to verify the modeling based on the multi-body systems is also considered.     

Three-dimensional tool radius compensation for multi-axis peripheral milling

Few function about 3D tool radius compensation is applied to generating executable motion control commands in the existing computer numerical control (CNC) systems. Once the tool radius is changed, especially in the case of tool size changing with tool wear in machining, a new NC program has to be recreated. A generic 3D tool radius compensation method for multi-axis peripheral milling in CNC systems is presented. The offset path is calculated by offsetting the tool path along the direction of the offset vector with a given distance. The offset vector is perpendicular to both the tangent vector of the tool path and the orientation vector of the tool axis relative to the workpiece. The orientation vector equations of the tool axis relative to the workpiece are obtained through homogeneous coordinate transformation matrix and forward kinematics of generalized kinematics model of multi-axis machine tools. To avoid cutting into the corner formed by the two adjacent tool paths, the coordinates of offset path at the intersection point have been calculated according to the transition type that is determined by the angle between the two tool path tangent vectors at the corner. Through the verification by the solid cutting simulation software VERICUTwith different tool radiuses on a table-tilting type five-axis machine tool, and by the real machining experiment of machining a soup spoon on a five-axis machine tool with the developed CNC system, the effectiveness of the proposed 3D tool radius compensation method is confirmed. The proposed compensation method can be suitable for all kinds of threeto five-axis machine tools as a general form.     

基于综合评价体系的五轴数控机床加工性能评价和误差溯源方法

五轴数控机床的加工性能在制造行业一直是研究的热点,基于检验试件切削是常见的测评方法,然而试件和机床之间的映射关系难以确定,出现误差后如何调整精度成为难点。为了科学对其评价,通过仿真平台建立了机床控制系统参数与五轴机床检验试件——S试件加工误差之间的映射关系,引入机床各轴分类评价的隶属度,此基础上开发了误差溯源的综合评价体系,由三坐标测量机得到的S件轮廓误差数据反求出机床的加工性能等级和较差的轴类控制参数,并制订了基于S试件的机床加工精度测评规范,最后通过某五轴AB摆数控机床的切削试验,验证了方法的有效性。该成果有助于解决我国高端制造业长期缺乏机床性能测评的共性技术问题,具有重要的应用前景和经济价值。     

双转台五轴机床空间误差补偿技术研究

几何误差、热误差和切削力误差占到了机床总误差的75%,对这3项误差进行控制是提高机床加工精度的关键所在。以双转台五轴机床的空间误差作为研究对象,通过对加工位置、主要热源及电动机电流等相关因素进行分析,确定空间误差建模所需的位移变量、温度变量和切削力变量。以现有的多种误差建模方法为基础,通过对信息融合技术进行研究,提出一种机床空间误差的多模型融合预测方法,建立综合反映几何误差、热误差和切削力误差的最优空间误差模型。最后以DSP为核心,设计空间误差补偿器,实施空间误差补偿,验证补偿效果。结果显示,建立的模型预测精度较高,残差小于2μm,而实施空间误差补偿后,加工零件的轮廓误差也由15μm降到了5μm,补偿效果明显。     

多轴数控机床新型自动拉松刀机构分析

多轴机床的代表是五轴联动机床,其加工效率高、精度高,是数控机床先进技术的体现。对数控机床中一种新型的自动拉松刀机构结构进行分析,提出其设计制造过程的重点考虑因素。     

The Denavit and Hartenberg approach applied to evaluate the consequences in the tool tip position of geometrical errors in five-axis milling centres

In this work, a methodology for the estimation of the geometrical accuracy of five-axis milling centres is developed by using the well-known formulation proposed by Denavit and Hartenberg. Five-axis milling centres are kinematically much more complex than three-axis centres and, therefore, the consequences of parallelism and squareness errors between elements and joints are not as easily calculated. In the method presented here, assembly errors are introduced as additional geometric parameters in the element transformation matrices, resulting in the real transformation matrix for a real and, therefore, imperfect five-axis milling machine. This matrix defines the real position of the tool in the absolute reference system. Three types of machine structures have been studied, which are the most commonly built, assembled and sold: gantry with a two-rotary-axes head, transverse column with a two-rotary-axes tilting table and, finally, a machine with a swivelling spindle and rotating plate. Each of the elemental errors is described and the way to introduce them into the Denavit and Hartenberg matrices is proposed. Some of the errors can be measured using the ISO standard procedures but others must be measured using special experiments, which are described in Sect. 4 of this paper. Finally, a real application of the proposed methodology to improve the precision of a multi-axis drilling operation is explained.     

在数控机床上通过监视主轴电机负荷实时监控刀具寿命

金属切削刀具的磨损和损坏直接影响到加工质量,因此有必要在生产实践中对刀具进行实时监控。刀具磨损或损坏时,切削力会发生变化,主轴电动机负荷也会发生变化,因此,可以根据主轴电动机负荷判断切削刀具是否到达寿命。本文探索了一种在数控机妹上通过监视主轴电动机负荷实时监控刀具寿命的方法,并给出了具体的实现技术及PLC和CNC程序。     

CNG车载瓶端部机械加工柔性组合机床的开发

针对传统CNG车载瓶加工缺少数控专机造成大质量CNG车载瓶加工质量较差和生产效率低下等技术问题,将基于移置式多轴机床的旋风切削、基于图像反馈的刀具切削路径误差补偿、面向绿色切削的雾化冷却技术等进行组合应用,开发了CNG车载瓶端部机械加工柔性组合机床,实现了高速平稳切削,快速可靠换刀,自适应性补偿缺陷,高效环保的刀具冷却。结果表明,组合机床的应用使得CNG车载瓶加工技术的自动化程度、加工精度和生产效率都得到了明显提高。     

基于UG的螺旋叶片数控五轴加工

为提高螺旋叶片的加工效率和质量,提出了一种新的综合优化方法.以螺旋叶片高效率、高质量、无干涉五轴加工刀具轨迹为目标,采用UG CAM可变轴曲面轮廓铣的曲面区域驱动方法,选择合适的投影矢量方向和刀轴方向,采用合理的加工工艺、切削用量和优化进退刀,采用自定义的后处理文件生成了相应数控系统的数控代码实验结果表明该零件的加工质...