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基于 平动 并联 机构 机床 运动学 分析 设计 CAD

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附录外文文献TOOLS USING KINETOSTATIC PERFORMANCE1. INTRODUCTION 2. Most industrial machine tools have a serial kinematic architecture, which means that each axis has to carry the following one, including its actuators and joints. High Speed Machining highlights some drawbacks of such architectures: heavy moving parts require from the machine structure high stiffness to limit bending problems that lower the machine accuracy, and limit the dynamic performances of the feed axes. That is why PKMs attract more and more researchers and companies, because they are claimed to offer several advantages over their serial counterparts, like high structural rigidity and high dynamic capacities. Indeed, the parallel kinematic arrangement of the links provides higher stiffness and lower moving masses that reduce inertia effects. Thus, PKMs have better dynamic performances. However, the design of a parallel kinematic machine tool (PKMT) is a hard task that requires further research studies before wide industrial use can be expected.Many criteria need to be taken into account in the design of a PKMT. We pay special attention to the description of kinetostatic criteria that rely on the conditioning of the Jacobian matrix of the mechanism. The organisation of this paper is as follows: next section introduces general remarks about PKMs, then is explained why PKMs can be interesting alternative machine tool designs. Then are presented existing PKMTs. An application to the design of a small-scale machine tool prototype developed at IRCCyN is presented at the end of this paper.2. ABOUT PARAL KINEMATIC MACHINES2.1. General RemarksThe first industrial application of PKMs was the Gough platform (Figure 1), designed in 1957 to test tyres1. PKMs have then been used for many years in flightsimulators and robotic applications2 because of their low moving mass and high dynamic performances. Since the development of high speed machining, PKMTs have become interesting alternative machine tool designs3, 4.Figure 1. The Gough platformIn a PKM, the tool is connected to the base through several kinematic chains or legs that are mounted in parallel. The legs are generally made of either telescopic struts with fixed node points (Figure 2a), or fixed length struts with gliding node points (Figure 2b).Along with high-speed cuttings unceasing development, the traditional tandem type organization constructs the platform the structure rigidity and the traveling carriage high speed becomes the technological development gradually the bottleneck, but the parallel platform then becomes the best candidate object, but was opposite in the tandem engine bed, the parallel working platform had the following characteristic and the merit:中文翻译1介绍 多数工业机床有一个串行运动学架构，这意味着每个轴进行下列工作时，包括其执行机构和联接点高速加工突出了一些弊端，例如架构:较重的运动部件需要从机械结构高刚度，以限制弯曲问题，即降低机床精度，并限制动态表现的曲线。这就是为什么并联机床吸引了越来越多的研究人员和公司，因为它们据称提供了单独的优势，如高结构刚度和高动态的能力。事实上，并联安排的联系，可提供更高的刚度和较低的误差，减少惯性的影响。因此，并联机床有更好的动态性能。然而，设计一个并联机床是一个艰巨的任务，在进一步的研究之前，广泛地在工业用途中的调研，是必不可少的。许多标准要考虑到在设计一个并联机床。我们要特别注意描述并联机床标准依赖于现在的雅可比矩阵的机制。该组织的这份文件具体内容如下:未来介绍总论约并联机床，那就是解释了为什么并联机床是不可替代机床的设计。一个设计中的应用了一次小规模的机床样机研制irccyn。2关于并联机床2.1总论 第一次工业应用并联机床是TheGough平台(图1)设计于1957年，以测试tyres1。并联机床当时已使用多年，在飞行模拟器和机器人applications2因为他们的低移动质量和高动态表演。由于发展的高速切削加工，并联机床已成为有趣的替代机床。随着高速切削的不断发展，传统串联式机构构造平台的结构刚性与移动台高速化逐渐成为技术发展的瓶颈，而并联式平台便成为最佳的候选对象，而相对于串联式机床来说，并联式工作平台具有如下特点和优点:(1)结构简单、价格低机床机械零部件数目较串联构造平台大幅减少，主要由滚珠丝杠、虎克铰、球铰、伺服电机等通用组件组成，这些通用组件可由专门厂家生产，因而本机床的制造和库存成本比相同功能的传统机床低得多，容易组装和搬运。(2)结构刚度高由于采用了封闭性的结构(closed-loopstructure)使其具有高刚性和高速化的优点，其结构负荷流线短，而负荷分解的拉、压力由六只连杆同时承受，以材料力学的观点来说，在外力一定时，悬臂量的应力与变形都最大，两端插入(build-in)次之，再来是两端简支撑(simply-supported)，其次是受压的二力结构，应力与变形都最小的是受张力的二力结构，故其拥有高刚性。其刚度重量比高于传统的数控机床。(3)加工速度高，惯性低如果结构所承受的力会改变方向，(介于张力与压力之间)，两力构件将会是最节省材料的结构，而它的移动件重量减至最低且同时由六个致动器驱动，因此机器很容易高速化，且拥有低惯性。(4)加工精度高由于其为多轴并联机构组成，六个可伸缩杆杆长都单独对刀具的位置和姿态起作用，因而不存在传统机床(即串联机床)的几何误差累积和放大的现象，甚至还有平均化效果(averagingeffect);其拥有热对称性结构设计，因此热变形较小;故它具有高精度的优点。(5)多功能灵活性强由于该机床机构简单控制方便，较容易根据加工对象而将其设计成专用机床，同时也可以将之开发成通用机床，用以实现铣削、镗削、磨削等加工，还可以配备必要的测量工具把它组成测量机，以实现机床的多功能。这将会带来很大的应用和市场前景，在国防和民用方面都有着十分广阔的应用前景。(6)使用寿命长由于受力结构合理，运动部件磨损小，且没有导轨，不存在铁屑或冷却液进入导轨内部而导致其划伤、磨损或锈蚀现象。(7)Stewart平台适合于模块化生产对于不同的机器加工范围，只需改变连杆长度和接点位置，维护也容易，无须进行机件的再制和调整，只需将新的机构参数输入。(8)变