外文翻译=设计并联机床=4000字符@中英文翻译、机械机电毕业外文翻译

机 0405 11 号 马吟川 指导老师：许宝杰 1 设计并联机床 使用 kinetostatic 标准 的 表现 /ftp/arxiv/papers/0705/0705.1038.pdf 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 现有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 The Gough 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。 图 1 The Gough platform 机 0405 11 号 马吟川 指导老师：许宝杰 2 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-loop structure)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(averaging effect)；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) 变换座标系方便 由于没有实体座标系，机床座标系与工件座标系的转换全部靠软件完成，非常方便。 Stewart 平台应用于机床与机器人时，可以降低静态误差 (因为高刚性 )，以及动态误差 (因机 0405 11 号 马吟川 指导老师：许宝杰 3 为低惯量 )。而 Stewart 平台的劣势在于其工作空间较小，且其在工作空间上有着奇异点的限制，而串联工作平台，控制器遇到奇异点时，将会计算出驱动装置无法达成的驱动命令而造成 控制误差，但 Stewart 平台在奇异位置会失去支撑部分方向的力或力矩的能力，无法完成固定负载对象。 在并联机床，工具 是以底座作为支撑做伸缩性运动 ， 下图为伸缩运动简图。 一般均作 伸缩臂 的同固定结点（图 2A ）条，或固定长度的 伸缩臂 与滑 动 结点（图 2b ）条。 图 2a A bipod PKM 图 2b A biglide PKM 2 2 奇点 奇异的配置（也称为奇点）的一个并联机床可能出现内工作空间或在其 边界 。有两种类型的 奇点 。一个配置 叫做 有限 速率 ， 在结点处需要极大的速率， 是所谓的一个序列奇异性 。配置工具不能抗拒任何 阻力 ，并 且会 转变得无法控制， 所谓平行奇异。平行的奇异尤其不可取因为他们 导致 以下几个问题： 结点处受力过高 ，这可能会损害结构，减少了该机制的刚度， 这会 导致无节制的运动规律工具虽然驱动关节锁死。 图 3A 及 3B 及第查看奇异为 biglide 机制图。 图 2B 在图 3 A ，我们有一个串行奇异。速度放大系数沿垂直方向是无效的力量放大系数是无限的。 图 3B 及第显示一个平行的奇异性。速度放大系数是无穷 ， 沿着垂直方向和部队放大系数是接近于零。注 ： 一高流速放大机 0405 11 号 马吟川 指导老师：许宝杰 4 系数并不一定是可取的，因为舵机编码器分辨率扩增 ，因此，准确度较低。 图 3a. A serial singularity 图 3b. A parallel singularity 2.3 工作和 装配 方式 一个序列（或平行）的奇异性，是与转变工作 模式 6（或者装配模式）。举例来说， biglide有四种可能的工作模式某一特定工具的位置（每 个 结点的，可以向左边或到右边的中间位置相对应的串行奇异，在图 4A ）及两项 装配 模式，为 某个结点处进行输入 （该工具是高于或低于此水平线对应平行的奇异性，图 4 ）。选择 装配 模式和该工作模式，可 明显 影响的行为机制。 图 4a. The four working modes 机 0405 11 号 马吟川 指导老师：许宝杰 5 图 4b. The two assembly modes 3 并联机床 作为替代机床设计 3 1 局限性串行机床 今天，新设计的机床受益于技术的改进部件，如主轴，线性传动，轴承。多数机床是基于串行架构（图 5），其优点是输入 /输出关系，是简单的。 3.2 并联机床 潜力机床设计 低移动质量的 并联机床 和良好的刚度，使 速率 （截至 100 米 /分钟）和加速度（ 1 至 5克） ，这是 我们设计并联系统 所需要的高速切削加工。 并联机床 是非常准确的， 确切 地说在有些情况下不是这样的， 只有在牵引或压缩 时，才会显现出来 。但是，也有许多结构性差异，串行和并行机床，这使得 让他们的表现 很难 它的优势才能被突出体现。 3.3 并联机床带来的问题 a) 这个工作一并联机床已不是一个简单的几何形状，它的功能量减少了，相比，要占用的空间，我们可以看图五 。 图 5 Workspace sections of Tricept 805 机 0405 11 号 马吟川 指导老师：许宝杰 6 b) 对于一个串行的机制，在速度和 扭矩 投送比例是常数 的 工作空间。 作 为并行的机制，相比之下，这些比例可能会有所变动 显著 ，因为位移的工具并不是线 性关系到位移的驱动装置。在某些部分的工作空间，最大 进给速度 和 进给时的受力 ， 会有 最大速度和力量驱动能 的 产生 ，这一点尤为如此 。 在奇异性，速度，准确性和力量的比例达到极端价值观。 c) 标定 并联机床 是个相当复杂的， 这取决于 运动学模型 本身的复杂性 。 4 现有 并联机床 设计 4.1 充分并联机床 我们所说的充分并联机床是 并联机床 有许多程度新闻自由作为支撑。对图 7 ，我们可以看到一个 3 自由度 的充分并联机构 3 伸缩臂 的。每一支杆材料是一种旋转接头，棱柱驱动关节和旋转联合。 图 6 3-RPR fully parallel mechanism 充分 并联机床 变长了 伸缩臂 是所谓 hexapods 。 hexapods 是灵感源于 The Gough 平台。第一 个并联机床 是六足 variax 吉丁斯和刘易斯在 1994 年在 imts 在芝加哥。 hexapods 6 自由度。多一个最近的例子就是 cmw300 ，六足头设计由 度 （图 7 ） 图 7 Hexapod CMW 300 充分并联机床与固定长度的 伸缩臂 能有三，四或六只脚。该 urane 的 SX（ figures8 和13 ），从雷 诺自动化是一个三腿机，其刀具只能沿 X ， Y 和 Z 轴，其建筑灵感来自三角洲机 0405 11 号 马吟川 指导老师：许宝杰 7 robot9 ，设计，取放申请。该六米，丰田是一个 六个伸缩臂的 并联机床（图 9 ）。 图 8 Renault automation Urane SX 图 9 Toyoda Hexa M 4.2 其他并联机床 该 tricept 805，是一种广泛使用的 并联机床 增加 了 伸缩臂的长度 （图 5 和第 10 条） 。该 tricept 805 有一个混合结构：两自由度手腕串联安装在一个三角架结构。 另一项 则是 不完全平行，是（图 11 ）由塞纳 technology10 ， 11 。 这 种偏离类型 是一个 overactuated 并联机床快速加工，有能力 一次性加工五个表面，这归功于有 了第二主轴。 图 10 Tricept 805 from Neos robotics 机 0405 11 号 马吟川 指导老师：许宝杰 8 图 11he Eclipse, from Sena Technology 5 设计一个并联机床 5.1 总体设计 为了满足当今时代 需要， 我们所需要 的机器将设计通过一套设计参数，如机器形态（串行，并行或混合运动学结构），这台机器几何（连接尺寸，联合的方向和联合不等），类型的致动器（线性或旋转电机 ），该型伸缩缝（棱柱形或旋转），数量和类型的自由度工作 。 5.2 并联机床 达到足够标准 只有这样，在设计过程中 ， 才能应 对 由于奇点是整合并联机床业绩标准。并联机床业绩标准评价能力的一个机制来传送力量还是速度，从励磁机，以该工具。这些并联机床业绩标准必须能够保证最低刚度，精度和速度的表演，沿各个方向在并联机床整的个工作区。 为了实现这一目标，我们使用两种互补的标准： 现有 的雅可比矩阵 J 号的并联机床，所谓调理指数，以及可操作性椭球与 j12 。雅可比矩阵 j 涉及联合利率工具速度等。这也涉及静态工具，努力动的努力。该空调指数的 定义是，两者的比例约为最高及最小特征值 J 的空调指数不同，从 1 到无限大。在一个奇异，该指数是无限大。这是一在另一项特殊的配置要求各向同性的配置。在此配置模式下， 工具，速度和刚度都是平等的全方位方向发展。该空调指数措施该均匀分布的速度，并努力靠近一个给配置，但并不告知有关的速度扩增或 阻力 因素。 该操作性椭球的定义是从矩阵。主轴线该椭球的定义是由特征向量和长度的主体是平方根的特征值。特征值有联系与速度（或强迫）扩增因素沿主轴线的可操作性。 这些标准是用来在 wenger13 ，优化工作空间形状和表演的均匀程度 orthoglide ，三自由度的并联机床专用铣 削时 应用（图 12 ） 。 图 12 A section of Orthoglides optimised workspace 机 0405 11 号 马吟川 指导老师：许宝杰 9 5.3 技术问题 如果 并联机床的伸缩臂因为过热而锁死 ， 则 并联机床 的 准确性 与伸缩臂 的翘曲由于供热所造成的摩擦所产生的 热量有关 。因此，除了制造不准确，标定一个 让并联机床 不得不顾及的 尺寸变化是由于 热量引起的膨胀 。一个良好的散热疏散，可减低影响 热量 。 6 结论 本文的目的是要引入一个准则，为设计 并联机床 ，有可能成为有趣的替代品，为高速切削加工，特别是在铣削大型零部件制成的硬质材料，或用于串行制造业务， 尤其是 航空零部件。 kinetostatic 标准似乎应该很好地适应设计 并联机床 ，特别是为运动学设计和优化的工作空间形状，对于表 现 统一性。 该 kinetostatic 准则已用于设计的 orthoglide ，三轴式 并联机床 开发 irccyn 。小规模的原型正在开发之中。机 0405 11 号 马吟川 指导老师：许宝杰 10 THE DESIGN OF PARALLEL KINEMATIC MACHINE TOOLS USING KINETOSTATIC PERFORMANCE CRITERIA /ftp/arxiv/papers/0705/0705.1038.pdf 1. INTRODUCTION 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 PARALLEL KINEMATIC MACHINES 2.1. General Remarks The 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 flight simulators 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. 机 0405 11 号 马吟川 指导老师：许宝杰 11 Figure 1. The Gough platform In 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: (1) structure is simple, the price is low The engine bed mechanical spare part number is series connected constructs the platform to reduce largely, mainly by the ball bearing guide screw, the Hooke articulation, the ball articulation, the servo electrical machinery and so on common module is composed, these common modules may by the special factory production, thus this engine beds manufacture and the inventory cost are much lower than the same functions traditional engine bed, easy to assemble and the transporting. (2) structure rigidity is high Because used closeness structure (closed-loop structure) to enable it to have high rigid and the high speed merit, its structural load streamline was short, but shouldered decomposes pulls, the pressure also to withstand by six connecting rods, by materials mechanics viewpoint, when the external force was certain, the bracket quantitys stress and the distortion were biggest, the both sides inserted the (build-in) next best, came is again both sides Jan supports (simply-supported), next was the bearing two strength structure, what the stress and the distortion were smallest was the tensity two strength structure, therefore it had the high rigidity. Its rigidity load ratio is higher than traditional the numerically-controlled machine tool. (3) processing speed is high, the inertia is low If the structure withstands the strength will change the direction, (will be situated between tensity and pressure), two strength components will be most save the material the structure, but it will move to the moving parts weight to reduce to lowly and simultaneously will actuate by six actuating units, therefore machine very easy high speed, and will have the low inertia. (4) working accuracy is high Because it for the multiple spindle parallel organization composition, six expandable pole poles long alone has an effect to cutting tools position and the posture, thus 机 0405 11 号 马吟川 指导老师：许宝杰 12 does not have the traditional engine bed (i.e. connects engine bed) the geometrical error accumulation and the enlargement phenomenon, even also has the being uniform effect (averaging effect); It has the hot symmetrical structural design, therefore the thermal deformation is small; Therefore it has the high accuracy merit. (5) multi-purpose flexible Is convenient as a result of this engine bed organization simple control, easily according to processing object, but designs it the special purpose machine, simultaneously may also develop the general engine bed, with realizes the milling, boring, processings and so on grinding, but may also provide the essential measuring tool to compose it the measuring engine, realizes engine beds multi-purpose. This will bring the very big application and the market prospect, has the very broad application prospect in the national defense and the civil aspect. (6) service life is long Because the stress structure is reasonable, the moving part attrition is small, and does not have the guide rail, does not have the iron filings either the refrigerant enters the guide rail interior to cause it to scratch, the attrition or the corrosion phenomenon. (7) Stewart platform suits in the modular production Regarding the different machine scope, only need change the connecting rod length and the contact position, maintains also easily, does not need to carry on parts remaking and to adjust, only need the new organization parameter input. (8) transformation coordinate system is convenient Because does not have the entity coordinate system, the engine bed coordinate system and the work piece coordinate system transform depend on the software to complete completely, is convenient. When the Stewart platform applies in the engine bed and the robot, may reduce the static error (, because high rigidity), as well as dynamic error (because low inertia). But Stewart the platform inferiority lies in its working space to be small, and it has the singular point limit in the working space, but the serial operation platform, the controller meets time the singular point, accountant will figure out the actuation order which the drive is unable to achieve to create the ning error, but the Stewart platform will lose the support partial directions in the strange position the strength or moment of force ability, will be unable to complete the constant load object. Figure 2a. A bipod PKM 机 0405 11 号 马吟川 指导老师：许宝杰 13 Figure 2b. A biglide PKM 2.2. Singularities The singular configurations (also called singularities) of a PKM may appear inside the workspace or at its boundaries. There are two types of singularities5. A configuration where a finite tool velocity requires infinite joint rates is called a serial singularity. A configuration where the tool cannot resist any effort and in turn, becomes uncontrollable, is called a parallel singularity. Parallel singularities are particularly undesirable because they induce the following problems: - a high increase in forces in joints and links, that may damage the structure, - a decrease of the mechanism stiffness that can lead to uncontrolled motions of the tool though actuated joints are locked. Figures 3a and 3b show the singularities for the biglide mechanism of Fig. 2b. In Fig. 3a, we have a serial singularity. The velocity amplification factor along the vertical direction is null and the force amplification factor is infinite. Figure 3b shows a parallel singularity. The velocity amplification factor is infinite along the vertical direction and the force amplification factor is close to zero. Note that a high velocity amplification factor is not necessarily desirable because the actuator encoder resolution is amplified and thus the accuracy is lower. Figure 3a. A serial singularity 机 0405 11 号 马吟川 指导老师：许宝杰 14 Figure 3b. A parallel singularity 2.3. Working and Assembly Modes A serial (resp. parallel) singularity is associated with a change of working mode6 (resp. of assembly mode). For example, the biglide has four possible working modes for a given tool position (each leg node point can be to the left or to the right of the intermediate position corresponding to the serial singularity, Fig. 4a) and two assembly modes for a given actuator joint input (the tool is above or below the horizontal line corresponding to the parallel singularity, Fig. 4b). The choice of the assembly mode and of the working mode may influence significantly the behaviour of the mechanism5. Figure 4a. The four working modes Figure 4b. The two assembly modes 机 0405 11 号 马吟川 指导老师：许宝杰 15 3. PKMs AS ALTERNATIVE MACHINE TOOL DESIGNS 3.1. Limitations of Serial Machine Tools Today, newly designed machine tools benefit from technological improvements of components such as spindles, linear actuators, bearings. Most machine tools are based on a serial architecture (Figure 5), whose advantage is that input/output relations are simple. Nevertheless, heavy masses to be carried and moved by each axis limit the dynamic performances, like feed rates or accelerations. That is why machine tools manufacturers have started being interested into PKMs since 1990. 3.2. PKMs Potentialities for Machine Tool Design The low moving mass of PKMs and their good stiffness allow high feed rates (up to 100 m/min) and accelerations (from 1 to 5g), which are the performances required by High Speed Machining. PKMs are said to be very accurate, which is not true in every case4, but another advantage is that the struts only work in traction or compression. However, there are many structural differences between serial and parallel machine tools, which makes it hard to strictly compare their performances. 3.3. Problems with PKMs a) The workspace of a PKM has not a simple geometric shape, and its functional volume is reduced, compared to the space occupied by the machine7, as we can see on Fig. 5 Figure 5. Workspace sections of Tricept 805 b) For a serial mechanism, the velocity and force transmission ratios are constant in the workspace. For a parallel mechanism, in contrast, these ratios may vary significantly in the workspace because the displacement of the tool is not linearly related to the 机 0405 11 号 马吟川 指导老师：许宝杰 16 displacement of the actuators. In some parts of the workspace, the maximal velocities and forces measured at the tool may differ significantly from the maximal velocities and forces that the actuators can produce. This is particularly true in the vicinity of THE DESIGN OF PKMT USING KINETOSTATIC PERFORMANCE CRITERIA 5 singularities. At a singularity, the velocity, accuracy and force ratios reach extreme values. c) Calibration of PKMs is quite complicated because of kinematic models complexity8. 4. EXISTING PKMT DESIGNS In this section will be presented some existing PKMTs. 4.1. Fully Parallel Machine Tools What we call fully parallel machine tools are PKMs that have as many degrees of freedom as struts. On Fig. 7, we can see a 3-RPR fully parallel mechanism with three struts. Each strut is made of a revolute joint, a prismatic actuated joint and a revolute joint. Figure 6. 3-RPR fully parallel mechanism Fully PKMT with six variable length struts are called hexapods. Hexapods are inspired by the Gough Platform. The first PKMT was the hexapod “Variax” from Giddings and Lewis presented