一种新型混联机床原型构想及运动学分析

在机械制造领域,混联机床结合了并联机床和传统机床的主要优点,它既有高的刚度,也有大的工作空间,它作为加工机床的理想补充已被许多学者接受。一种新型的混联机床是由一个空间三自由度(两个移动和一个转动)的并联机构和一个XY平面二自由度(两个移动)的工作平台组成,可以作为高速多自由度的加工中心,扩大机床的加工范围。对空间三自由度的并联机构的正向运动学和逆向运动学进行了分析和研究,并使用MATLAB软件编程,给出了数值实例。     

3-SPS/UPR并联工作台运动学分析

提出一种以3-SPS/UPR并联机构为主体的工作台,用以辅助少自由度机床对工件进行曲面加工。建立3-SPS/UPR并联机构的运动螺旋矩阵,通过螺旋理论对其进行自由度分析,采用修正的Kutzbach-Grübler公式进行验证;通过机构中的几何关系,采用封闭矢量法求解该机构的位置逆解,并求出该机构的速度Jacobian矩阵;通过三维动态搜索法求解该机构的工作空间;通过Adams软件对该并联工作台进行了运动学仿真。该3-SPS/UPR并联机构能够进行两平移两转动的运动,可提高机床加工效率和加工质量,增大机床加工范围,提高机床的曲面加工的能力。     

PRS-XY混联数控机床运动学仿真件开发

根据PRS-XY型混联机床结构特点构建机床运动学模型,介绍了其运动的逆解和正解过程.在Windows环境下,应用Visual C++6.0调用OpenGL实现了该机床的实体建模和运动学仿真.运动学仿真软件能够实时显示出机床机构形态、模拟出混联数控机床的加工运动过程,可实现并联机构干涉校验,进而保证加工轨迹规划的合理性、...     

一种新型4自由度并联机床构型设计与运动学分析

提出了一种能实现沿y轴、z轴移动和绕x轴、y轴转动的新型4自由度部分解耦并联机构,将该并联机构辅以能实现主轴x轴移动和x轴转动的动平台,共同组成一种新型并联机床构型;此机床机构特为涡轮叶片加工而设计。对机构进行了运动学分析,得到了运动学方程和雅可比矩阵;使用几何方法对机构的工作空间进行了分析,利用雅可比矩阵证明工作空间没有奇点,并获得了给定任务下的机构执行器所需行程长度。     

多功能模块化串并联机床结构的研究

在分析当前机床技术发展的趋势的基础上，提出了一种新型模块化并联机床结构，机床主运动的实现采用并联机构，工件的进给运动由串联机构实现。研究了机床主运动模块平面二自由度机构的运动特性，给出了机构运动学正反解。机床采用模块化结构设计，据加工需要，可方便快捷地组合设计不同自由度的机床；运动机构串并联相结合，既具有结构简单，刚度重量比大，响应速度快的特点，又具有工作空间较大的特点。     

基于3-UPS机构并联机床的运动学分析

结合并联机床的机构特点,采用矢量法建立了3-UPS并联机床机构运动学模型,运用求导法推导了3-UPS机构的一阶影响系数矩阵,分析了机构的奇异性和平稳性。     

一种2RPS-RPU并联机构的动力学分析

Exechon混联机床因具有结构刚度大、良好的运动学和动力学特性等特点,广泛应用于高精密、快速加工中。但该机床的并联模块同时也具有转动范围小、工作空间窄等特点;为此,通过支链变异法,提出一种可满足机床2R1T运动要求的2RPS-RPU并联机构。利用杆长条件建立机构的位置反解方程,运动副速度投影推导系统的非满秩雅克比矩阵;并结合拉格朗日方法,推导了机构的动力学模型。最后采用Matlab对系统运动学、动力学进行数值计算,并绘制各个变化曲线,总结出该机构的基本运动和力学性能,其结果表明该机构也具有Exechon机床并联模块的良好的动力学特性等特点,为后续开发和改进该机床提供了新的并联模块构型和理论依据。     

一种五轴联动混联机床的性能分析

混联机床是串、并联机构以及机器人技术的结合,兼顾了各自优点,已越来越多地应用于复杂工件的加工中。提出一种可完成五轴联动的混联机床,同时分析该机床加工过程的实现及原理;基于并联模块中杆长约束条件,构建加工过程中的运动学模型;并利用速度投影,求解出并联模块雅可比矩阵;结合拉格朗日方程以及雅可比矩阵,建立机床动力学模型。最后结合Matlab对理论分析结果进行数值计算,并在已知机床切削量的情况下,求解机床驱动端位移、速度以及驱动力输入情况;结合运动学结果,对机床工作空间进行了分析。结果表明,该混联机床具有良好的运动学、动力学以及大范围工作空间等性能,并能满足复杂零部件的加工,也为混联机床的开发和研究提供理论依据。     

激光加工用三平移并联机床的分析与研究

设计与研究了一种用于激光加工的三平移并联机床。介绍了并联机床的组成及部件间的连接关系。通过应用并联机构拓扑结构理论对并联机床的自由度进行了分析,得出其自由度输出为三平移。通过建立杆长约束方程,得到并联机床机构的运动学位置逆解方程。应用几何法对并联机床工作空间进行了分析与求解,并得出工作空间与机床机构参数之间的关系。通过建立并联机床的几何参数误差模型,得到机床动平台的输出位置误差,进而为并联机床生产和运动控制提供理论依据。     

一种并联激光加工机床的运动学及工作空间研究

提出了一种基于并联机构的三平移并联激光加工机床,介绍了机床的组成部分,并进行了自由度求解。通过位置分析,建立杆长约束方程,得到了运动学逆解方程。应用Pro/E与Adams软件建立并联机床的数字化虚拟样机,定义动平台运动轨迹函数,进行了运动学仿真。通过仿真分析,得到了当激光加工头匀速加工情况下的驱动滑块的位移、速度、加速度曲线,并比较了滑块速度输入与动平台速度输出之间关系。最后对机床的工作空间进行了分析,得出工作空间大且无空洞的结论。上述工作,可为并联机床的设计与加工提供理论依据。     

高速机床的关键技术和发展趋势

在介绍高速切削和高速机床基本概念的基础上,分别从常规机床技术的改进、适应机床高速化而产生的新技术以度机床结构创新等角度,分析了当今高速机床中应用较广泛的高速滚珠丝杠、电主轴、直线电机、并联机床等关键技术,并介绍了国内外高速机床的发展趋势。     

CIMT’97主要展品的技术特点综述

两年一度的中国国际机床展览会是国际机床界和我国机械制造业的一件盛事。第五届中国国际机床展览会(CIMT’97)又一次荟萃了国内、外各机床厂及相关配套件厂和工具厂的精华,既可看到一些名牌企业享有盛名的产品,也会发现一些脱颖而出的新秀企业所展示的精品。从展览会上我们能深刻地领会到机床工具行业的发展动向,也能生动地观察到琳琅满目的新产品和新结构。从中既反映了丰富多采的世界先进实用制造技术和最新制造技术,也展示了中国机床工具行业通过“三大战役”在增强开发能力和竞争实力方面所取得的可喜的巨大进步。     

A hybrid 5-axis CNC milling machine

5-Axis CNC milling machines are important in a number of industries ranging from aerospace to consumer-die-mold machining because they can deliver high machining accuracy with a spindle tilting capacity. Most of these machines have serial mechanisms so that modest static and dynamic stiffness become very critical design issues when high speed machining capability is required. Parallel mechanisms have recently received attention from machine tool designers because of their inherent potential for stiffness and because of their compactness. However, much of the promised advantages of parallel machines only occur within a very small region of their workspace. We discuss some of the kinematic and structural challenges to extract machining performance from serial and parallel machines. We compare a hybrid machine, which combines serial and parallel mechanisms, with typical serial and parallel machines such as Euler angle machines and a hexapod. In particular, we consider singularities, reversal characteristics, and manufacturability. We show that hybrid machines can benefit from the advantages of serial and parallel mechanisms while avoiding most potential pitfalls. However, hybrid structures can suffer from the manufacturing problem of over-constraint. We show that the degree of over-constraint depends on machine size. We have designed a small hybrid 5-axis motion platform, the MIT-SS-1, which can tolerate this over-constraint through a novel layout of axes. We show that this structure has potential as a small 5-axis CNC milling machine.     

铰刀的新结构——快换式铰刀系统

本文介绍了一种铰刀的新结构——快换式铰刀系统。它是对普通铰刀结构的重大改革,具有快速更换和成本显著降低的特点,适用于多种机床上进行高速铰孔,在数控机床、加工中心和柔性制造系统上使用时,效果尤其显著。     

制造技术与装备领域30年来的4大质变

回顾了机床的发展历史,归纳了智能型机床、快速成型加工、并联机床、新型工具等加工方式、设备和工具领域的革命性变化。总结了机床工具领域内国内外发展的最新动态,指出了该领域的发展方向。     

现代高速切削与工具技术

高速加工和高效加工是目前获得高效机械加工生产率的重要手段，它在航空和航天产品的零件制造、模具制造以及汽车零部件制造等领域有较大的需求。机床采用高速传动技术、高速进给技术、高速切削刀具，配以大功率或大扭矩主轴系统以及复合加工技术，可实现高速加工与高效加工。近几年我国在机床高速化技术方面的研究开发取得了长足进步，并开发出相应的主机产品，为我国数控机床向高速、高效和精密方向发展奠定了基础。     

提高CL90-51测速齿轮精车加工效率的研究

针对CL90-51测速齿轮在现阶段高速发展的轨道交通中的重要地位,通过分析原有精加工测速齿轮的机床、刀具、工艺等缺陷,提出了相应的改进措施,保证测速齿轮精加工的精准、高效。     

A review of recent developments in the design of special-purpose machine tools with a view to identification of solutions for portable in situ machining systems

With the ever increasing diversity of manufacturing and maintenance needs for modern products, the realm of machine tool design has expanded considerably in recent years. While machine tools for producing singular parts are widely documented, there is much less information available about machine tools for specialist tasks such as repair and maintenance. The paper aims to give an overview of the developments in the field of specialist machine tools and machining systems with a particular emphasis on maintenance operations and in situ machining. The difficulties of performing maintenance on large-scale systems are outlined along with the potential benefits of in situ machining in these applications. A number of examples of specialist machines for applications in various fields are described. The developing area of micro machine tools and micro factories is introduced along with examples of systems which have been developed or proposed. The possible advantages and draw-backs of the various technologies described are discussed. The paper goes on to comment on the potential for a new approach which combines these technologies to produce small in situ machine tools for performing macro-scale machining operations on large workpieces. These machining systems could offer increased versatility of in situ maintenance machining, compared to machines designed for a single repair operation, while reducing costs and environmental impacts.     

Improved Stiffness Modeling for An Exechon-Like Parallel Kinematic Machine(PKM) and Its Application

Hole drilling or contour milling for the large and complex workpieces such as automobile panels and aircraft fuselages makes a high combined demand on machining accuracy, stiffness and workspace of machining equipment. Therefore, a 5-DOF(degrees of freedom) parallel kinematic machine(PKM) with redundant constraints is proposed. Based on the kinematics analysis of the parallel mechanism using intermediate variables, the kinematics problems of the PKM are solved through equivalent kinematics model. The structural stiffness matrix method is adopted to model the stiffness of the parallel mechanism of the PKM, where the stiffness of each joint and branch component is obtained by stiffness formula and finite element analysis. And the stiffness model of the parallel mechanism is improved by correction coefficient matrix, each element of which is constructed as a polynomial function of three independent end variables of the parallel mechanism. The terminal stiffness matrices obtained by simulation result are used to determine the coefficients of polynomial function by least square fitting to describe the correction coefficient over the workspace of the parallel mechanism quantitatively. The experiment results prove that the modification method can greatly improve the stiffness model of the parallel mechanism. To enhance the machining accuracy of the PKM, the proposed kinematics model and the improved stiffness model are utilized to optimize the working stiffness of parallel machine by searching the best relative position of parallel machine and workpiece. A plate workpiece taken as example is examined in the case study section, which demonstrates the effectiveness of optimization method.