资源目录
压缩包内文档预览：(预览前20页/共27页)
编号：531255
类型：共享资源
大小：770.81KB
格式：ZIP
上传时间：2015-11-25
上传人：QQ28****1120
认证信息
个人认证
孙**（实名认证）
辽宁
IP属地：辽宁
6
积分
- 关 键 词：
-
机械毕业设计英文翻译
- 资源描述：
-
机械毕业设计49英文翻译外文文献翻译142,机械毕业设计英文翻译
- 内容简介：
-
英文资料 Evaluation of Size Effect on Micro-machine-tools Design for Microfactory M. Yamanaka1, S. Hirotomi2 and K. Inoue3 1Tohoku University, 6-6-01, Aramaki-Aoba, Sendai 980-8579, Japan, yamanakaelm.mech.tohoku.ac.jp 2Shimano Inc, Japan 3Tohoku University, Japan Abstract. A micro lathe with a machine base size of 150100 mm (postcard size) was developed by the authors. It has a good cutting performance for brass test workpieces. To know the developed machine is most suitable size for machining the given workpiece size, the error functions, which affect the cutting performance, are examined how to change to the machine tool size. The calculation method and a simple size effect of error functions are proposed and their usefulness is examined by some calculation results. Keywords: Microfactory, Machine tools, Lathe, Machine design, Size effect 1. Introduction Ordinary production systems use enlarged machine tools aiming at high rigidity regardless of the size of the parts produced. The concept of microfactory is to use small machine tools corresponding to the miniaturization of workpieces. This is useful for saving resources, space, and energy. Some prototypes were developed to realize this concept 1. Okazaki developed an NC micro lathe which is 322830 mm in size 1. Park developed a miniaturized 3-axis milling machine ntsof 200300200 mm 2. The authors are developing micro lathes aiming at the practical use in mass production systems of small/micro parts for optics, IT and electronics, until now 3. The machine with a base size of 150100 mm (postcard size) has been developed and the relation between machine characteristics and cutting performance are evaluated to clarify advantage/disadvantage of the developed lathe 4. To design micro machine tools, it is important to properly understand the merits and demerits of downsizing. Mishima proposed a design tools 5 combined with the form-shaping theory of machine tools6 and Taguchi method 7. It offers a simplified method to consider the deformation of machine tool structures and the component errors. The developed micro lathe has a good cutting performance for the test workpiece. However, it is obscure that the developed machine is most suitable size for machining the given workpiece size. It is impossible to make many sizes of machine tools and evaluate their performances. In this paper, the outline of developed micro lathe is introduced, and the influence of accuracies according to the machine size to the cutting performance is examined in a simulation. The calculation method considering the size effect on micro machine tools design is discussed with the calculation results. 2. Micro Lathe The maximum size of target workpiece was assumed to be5 10 mm and the lathe was designed. The size of the machine base was decided to be of A6 size nts(150100 mm) for its foot print area considering the degree of miniaturization, its practicality, assembly and, in particular, a sufficient rigidity. Each device of the machine was designed with this restriction. The developedmicro lathe MTS 2 (product of Nano Corporation, Japan) is shown in Fig. 1.1. X and Z-axis tables, which use the same modules, are guided by cross-roller ways, and driven by a 2-triangle screw thread and an AC 15-mm in square servomotor. The size of the table is about 5080 mm (excluding motor). The weight including the motor is 585 g. The headstock is fixed on the X-axis table and the tool post is mounted on the Z-axis table. Figure 1.1. Appearance of developed micro lathe MTS2 (Nano Corporation, Japan, base size: 150x100 mm) A micro motor of 16 mm diameter is used to drive the work spindle in the ntsheadstock from the balance with the table. A rotary speed of more than 10000 min-1 is necessary to obtain a cutting speed of about 150 m/min for small-diameter workpieces. Because of this, a direct drive is preferred, but a reducer is required to drive the workpiece because the motor torque of a 16 mm class motor is extremely small (only a few mNm), which is generally not enough to obtain a sufficient cutting power. The rotary speed is secured as much as possible by selecting a high-speed motor. The planetary roller reducer using traction drives is adopted for this work spindle. The reduction ratio is 4. The size and weight of the headstock is 754030 mm, its weight is 230 g (include motor). 3. Calculation of Error in Consideration of Size Effect There are many error functions, which affect the cutting performance. Here, only four error functions, namely the assembly error, the motion error, the deformation by cutting force and the thermal deformation, are considered, and how they change to the machine tool size is examined. Then we propose the calculation method of error in consideration of size effect. The model with dimensions of above-mentioned micro lathe and those of enlarged/reduced are used to calculate by using the formshaping theory. The deviation from the target position of the tool point is obtained and the proposed method is evaluated. 3.1 Calculation method The above-mentioned micro lathe is modeled as shown in Fig. 1.2. The model consists of eight elements. The numbers from 0 to 7 are given to the reference point in coordinate transformation on each element. Though the bed is ntsactually one solid component, it is divided into two parts virtually to consider the influence of the beds rigidity. The target position in the tool point is apart from the point 0 to h in Z-direction and R in X-direction, respectively. An orthogonal coordinate system Si corresponding to an element i is defined. The transformation from Si to Si+1 is represented by the coordinate transformation, which is represented by the homogeneous transformation matrices Ai. Vector rw represents the relative displacement between the workpiece and the tool, and vector rT represents the position of the tool point. The relation between rw and rT is given by Eq. (1), and rw is defined as the form-shaping function. The error between element i and i+1 is represented by another homogeneous transformation matrix i as follows. nts The form-shaping function considering the error is defined as rw expressed by The form-shaping error function re, which expresses the error as a quantitative deviation from the target position, is defined as Eq. (4). The error between elements of the micro lathe is represented by 6 components, which are translational and rotational motions along the X, Y and Z axes, as x, y, z, , , and , respectively. The limited four error functions may affect between elements shown in Fig. 1.3. The assembly error appears between all elements except between the bed 1 and the bed 2, which are divided into two parts. The motion error appears between the elements that move relatively during cutting. Because force and heat propagate through an element, the deformations by cutting force and heat appear between all elements. Moreover, as shown in Table 1, it was analyzed and classified which error components are affected by above-mentioned four error functions. For example, the motion error between the workpiece and the work spindle depends on the runout of the work spindle. Because the workpiece rotates around the Z-axis, the translational error in X and Y except Z-axes are ntsconsidered. The assembly error can not define the direction to appear, and is assumed to appear in all 6 components. The deformations by cutting force and heat are assumed to appear in 3 components of translationalerror. 3.2 Size effect of error Table 2 shows to what extent the amount of error of each item in Table 1 changes when the size of the machine tool is changed n times, which is examined by other reports 8,9 and the calculation. It is thought that the difficulty of assembly is constant regardless of the machine size. Therefore, the size effect of the assembly error is 1. The motion error depends on the accuracies of guides in a slide table or bearings in a work spindle. Here, it is considered that the machine element of same absolute accuracy can be selected regardless of the size, and the size effect of the motion error is assumed to be 1 as well as the assembly error. The cutting force is divided in 3 directions, namely principle, the thrust and the feed force. A simple bend and compression of beam according to the direction of applied force on each element is considered, the size effect of ntsdeformation by cutting force is assumed to be 1/n and 1/n2, respectively. If the temperature increases, generally a material expands. The deformation t of a member having a length can be calculated using the formula where, t is the linear coefficient of thermal expansion and T is the temperature rise of the member. Therefore, the size effect of thermal deformation is considered as n. The dimensions of each element of the model in Fig. 1.2 are required to calculate the error. The real dimensions of the developed micro lathe shown in Fig. 1.1, and ntsthese are used as that of a model for n= 1. Then the model is enlarged n times and the error in Eq. (4) is calculated by the method mentioned above using the size effect of errors shown in Table 1.2. And how the error changes according to n is examined changing n from 0.5 to 10. However, the dimensions of workpiece and tool are assumed to be constant regardless of n, where R is 2.5 mm, h is 10 mm and t is 8 mm. In this method, actual values of error are required for the calculation. Hence, the magnitude of each error for n= 1 is decided as shown in Table 1.1. The assembly and the motion errors were decided in consideration of actual micro lathe. Both errors can take a positive or negative value, and are expressed with the sign of + or -. The deformations by cutting force and heat are obtained by FEM. The deformation of workpiece and tool were not considered. The element 7 is fixed and the magnitude of deformation of each element is obtained. The tangent force applied to a workpiece is calculated by the rated torque of the motor of the work spindle, and it is assumed to be the principal cutting force. The ratio among 3-divided cutting forces is decided by the reference 8. The deformation of each element when the atmosphere rises by 20 K is calculated as the thermal deformation. Because the target is a cylindrical component, the errors R in cutting radius and z in longitudinal direction are defined as the evaluation function of error. R and R are the actual and instructed cutting radii, respectively. R is given as follows. The assembly and motion errors take positive or negative values in Table 1.1, ntsand the number of those items is 44. If the case of plus/minus in each item is combined, there are 244 patterns to calculate. This combination is so large that the orthogonal table in Taguchi method 7 is applied and the calculation is held in small combinations. Here, the orthogonal table of L64 is used to obtain re by Eq. (4) and the evaluation functions are calculated in 64 cases. nts The relation between the machine size n and the average of evaluation function is shown in Fig. 1.4. The max/min values are also plotted in the figure. The magnitude of R increases as n increases. The difference between the maximum and the minimum values increases too. The assembly error and the thermal deformation may be the reason for this. Though the magnitude of assembly error does not depend on n, as shown in Table 1.2, the movement in coordinate transformation becomes large as n increases, so that re becomes large. The thermal deformation increases because of its size effect. As for z, there is the minimum value near n = 1.5. z increases as well as R when n increases more than it. When n becomes small, z increases slightly by the size effect of the deformation by cutting force. This suggests that an optimum size of this kind of machine exists for a given size of workpiece. Here, R is set as 2.5 so that R x, y and R is almost constant from Eq. (6) though n becomes small. Each mean value for n is normalized by dividing by that for n= 1 to know the tendency of change of evaluation function to n. The result is shown in Fig. 1.5. R and z become 8 and 3.4 times as large as at n= 10. It can be said that the ntssensitivity of R to the machine size is higher. The calculation result by the proposed method changes greatly by the values of error and the size effect shown in Tables 1.1 and 1.2. In this study, though, the size effect of error functions was simplified, more examination is necessary to improve the accuracy of calculation. 4. Conclusions The influence of accuracies according to machine size on cutting performance is examined. The conclusions may be summarized as follows: 1. The error function, which affects the cutting performance, is examined. Then the calculation method of error in considerlation of size effect is proposed applying the form-shaping theory. 2. The calculation model is built by using the dimensions of the actual micro lathe. The relation between machine size and error is obtained. The assembly error and the thermal deformation have the strongest influence. References 1 Okazaki, Y., et al., (2004) Microfactory: Concept, historyand developments. Trans. ASME, J. ManufacturingScience and Engineering 126: 837-844 2 Park, J. K., et al., (2006) A precision meso scale machine tools with air bearings for microfactory. Proc 5th Int.Workshop on Microfactories, Besancon, France (CDROM) 3 Iijima, D, et al., (2004) Micro Turning System 3 (MTS3): A practical CNC lathe for microfactories. nts Proc. 4th Int. Workshop on Microfactories, Shanghai, China 1: 50-55 4 Yamanaka, M, et al., (2006), Relation between mechanical characteristic and cutting performance of micro lathe. Proc 5th Int. Workshop on Microfactories, Besancon, France(CD-ROM) 5 Mishima, N., (2003) Design of a Miniature Manufactuirng System for Micro-fabrication. Proc 10th Annual Conf. for Concurrent Engineering, Modeira, Pirtugal 1129-1135 6 Reshtov, D. N., Portman, V. T., (1988) Accuracy of machine tools. ASME Press, New York 7 Taguchi, G., Konishi, S., (1994) Quality engineering series. ASI Press 8 Sugita, T., et al., (1984) Fundamentals of cutting (in Japanese). Kyoritsu Publish. nts中文翻译 评价 为微型工厂设计的微型机床 的尺度效应 M. Yamanaka1, S. Hirotomi2 and K. Inoue3 1Tohoku University, 6-6-01, Aramaki-Aoba, Sendai 980-8579, Japan, yamanakaelm.mech.tohoku.ac.jp 2Shimano Inc, Japan 3Tohoku University, Japan 摘要 : 一种微型机床总体尺寸为 150 100 mm(明信片大小 )现在发展起来。它在切割黄铜制品的实验中表现出良好的性能。根据所给工件的大小，误差 函数 ，这些影响切削性能的方面来确定机床的大小。 受 计算方法和简单的尺寸的影响 的 误差函数的提出是 为 审查通过一些计算结果 。 关键词： 微型工厂 ，机床，车床 ， 机械设计，尺寸效应 1.导言 普通生产系统的使用大机床 是 针对高刚性，不论零件大小。 微型工厂的概念是用小机床相应的小型化工件。这是 对于 节省资源，空间 和 能源 是 有益的。一些原型 的 开发 就是 为 了 实现这 种观念 1。 冈崎研制出一种微型数控车床大小 为 322830 mm1。开发 的一种 微型 三 轴铣床 为 200300200 mm2。作者正在开发的微型车床着眼于实际使用在大规模生产系统中的小型 /微型光学部件，信息技术和电子产品，截至目前为止 3。 已经研制成功 的一种 机床 包括 基 座 面积 为 150100 mm（明信片 大小 ） ，正在做机床的 机 械 特 性与 切削加工性能两者之间关系的评价，以 彻底弄清这种 车床 的 优劣 4 。 设计微型机床 时 正确认识 到小型化所带来 优点和缺点是非常重要的。三nts岛提出了一个设计工具 5 结合 机床的仿型刨原理 6和田口原理 7。它提供了一种简化方法 去 考虑机床的结构变形和组件的 误差 。发 展起来的 微型车床 对于 测试工件 表现出 良好的切削加工性能。但是，所研制的机 床大小对于工件尺寸 是 否是 最合适模糊不清。 也 不可能 设计 许多大小 不同的型号的 机床来评估它们的表现 。 在这 篇论文 中介绍 的 微型车床， 对于 机器的大小 相对应的 切削加工性能对 于 精度 的 影响 已经 在一个仿真 中测试 。 设计微型机床时考虑到尺寸效应的计算方法与计算结果 已经被 讨论。 2 .微型车床 车床设计 时 目标工件 的 最大尺寸假设为 510 mm。 机床底座被设计为 A6尺寸（ 150100 mm） 考虑到它的小型化程度和实用性。 机器的每个 部 件 都 用此限制。 这种 微型车床 MTS2（ 由 日本 Nano 公司 生产 ） ，引进 Fig.1.1 X 和 Z 轴工作台，这种工作台 使用 相同的模块 ， 用交叉辊子导向 ， 用 2 三角螺纹与15mm 方形 交流伺服电机 驱动 。 工作台 大小是约 5080 mm（不包括 电机 。包括电机 的 重量 为 585g。主轴箱 固定在 X轴 上，刀架 装在 Z轴 上 。 nts 图 1.1 微型车床 MTS2 外观（ Nano 公司，日本，基 座 面积： 150x100mm） 装在主轴箱里的工作主轴是由 16毫米直径微电机驱动， 主轴箱与工作台相连。 转速超过 10000 转 /分钟对于切削 小直径工件 时 要取得切削速度约 150米 /分钟 是很必要的 。正因为如此，直接驱动是首选，但 是需用 减速机驱动工件，因为 16 毫米级电动机 的 转矩是非常小 的 （只有几 mNm ） ，一般不足够 提供 足够的切削功率。旋转的速度 可以 保 障 的 ，可以选择转速尽可能高的电机 。行星辊减速器用 来驱动 主轴。该 减速器 减 速比 是 4 。尺寸 为 754030 mm，它的重量是 230 g（包括电动机）。 3 .考虑到 尺寸效应 的 计算误差 有许多 误差函数会 影响 到 切 削性能 。在这里，只 考虑 四个误差函数，即装配误差，运动误差，切削力 导致的变形 和热变形，以及它们如何 影响 机床尺寸 已经被计算 。那么，我们提出的计算误差 的 方法 应 考虑尺寸效应。上文提到的微型车床和那些扩大 /减少 车床的 模型的尺寸是用 仿型刨理论 来计算nts的。计算出了刀尖偏离目标的距离，并且评价了这种理论。 3.1计算方法 上文提到的微型车床 的模型见 图 1.2 。该模型 分为 8 个部分 。号码从 0到 7 是个部分进行 坐标变换 时的 参考点。虽然 基座 实际上是一个 整 体组成，考虑 到刚度 的影响，它分为两个部 分。 目标位置在工具的一点是， 原 点 O 至刀尖点 在 Z 方向 是 h， 在 X 方向 是 R。 图 1.2.微型车床计算模型 定义一个 正交坐标系 Si 相当于部分 i.从 Si 到 Si+1的 坐标转换，是由奇次变换矩阵 Ai 所代表。 矢量 Rw代表工件和 刀 具之间相对位移，向量 RT 代表刀具位置 。 Rw 和 RT的关系有等式 （ 1） 给出 ， RW是定义为 仿型刨函数 。 nts 部分 i 和 i+1 之间 的 误差 由以下齐次变换矩阵 i 所示。 考虑到误差的仿型刨函数定义 为 rw， 表达 如下 仿型刨 误差函数 re，它体现了误差作为一个定量偏离了目标位置，是 由等式 （ 4）定义 。 微型车床 个 组件之间的误差 有 6部分组成 ， 它们分别是沿 X、 Y、 Z轴平移和绕它们旋转，记为 x, y, z, , , . 有限的四个误差函数可能会影响 如 图 1.3所示各部分 。误差会出现各要素之间除了 被 分为两部分 的基座 1和 基座 2。 该运动误差出 现在各部分在 切 削过程中的 相对 运动中 。因 为力 和热 量会传播， 由切削力和热 引起的变形会在各部件之间传播。 此外，如表 1所示，它分析和归类 了 受上述四项误差函数 影响的 误差项组成。举例来说 ， 工件和工作主轴之间的运动误差 取决于 工作主轴的 跳动。由于工件围绕 Z轴旋转 要考虑 Z轴除外的 沿 X和 Y轴的直线运动 误差。误差 出现的地方 不能确定 ，有可能出现在 所有 6个 组成部分。 切 削力和热 导致nts的 变形假定出现在平移误差 的 3个组成部分 。 3.2误差 的 尺寸效应 表 1.1 在 n=1 时，误差函数对误差个组成部分的影响和实际值 表 1.1 n=1 时，误差函数对误差各个组成部分的影响和实际值 表 2 显示， 当 机床 大小 改变了 N 倍时 ，表 1 中的各项的误差是 在何种程度上 变化 ， 这些已经被 其他报告 8， 9计算 和检验过 。 装配难 度是恒定的，与 机器尺寸 无关 。 因此， 尺寸 效应的装配误差是 1 。该运动误差取决于 安装在 工作主轴 上的导轨和 轴承的精度。这里，认为机器的 部件的精度可以选择 ，不论 尺寸 大小，而且运动误差 的尺寸 效应 和装配误差一样被假设为 1。切削力分为三方向，即原 发法向力 ，推力和 进给力 。 一个简单的弯曲和压缩的梁依照每一个元素的应力方向，由切削力导致的变形引起的尺寸效应分别假设为 1/n 和 1/ ，如果温度升高，一般的，金属会膨胀，长度 l 的形变 可以用以下公式计算 这里的 表示一 个 热膨胀的线性系， T 表示温度的增量。因此，热变形的尺寸效应用 n表示。 nts 图 1.3 微型车床的误差产生 nts 表 1.2 误差函数的尺寸效应 3.3结果与讨论 维度的每个单元的模型图 1.2 须计算误差。 高级的 微型车床实际尺寸 用图。 1.1 显示 ，而这些都是 n = 1 的模型 。那么该模型 被 放大 n倍 与 Eq 误差。 （ 4 ） 用上述在表 1.2 中提到的使用尺寸效应误差的方法计算。 以及如何 通过 改变 n 从 0.5 至 10 来改变 误差。然而 ，工件和刀具的 尺 寸 都被假定为恒不论 n ，其 R 是 2.5 毫米， h 是 10 毫米 t 是 8 毫米。在 此方法中， 误差的 实际值 是计算所必需的。 因此， 对于 n=1，每个误差的大小正如表 1.1所示是确定的。装配和运动误差是由微型车床来确定的。 这两个错误，可以采取正或负的价值，并表达 为符号 +或 -。 由切削力和热 引起的变形被 FEM 获得 。工件和刀具 的变形 没有考虑到。 元件 7 被确定和每个元件的变形大小也被获得了。
- 温馨提示:
1: 本站所有资源如无特殊说明，都需要本地电脑安装OFFICE2007和PDF阅读器。图纸软件为CAD,CAXA,PROE,UG,SolidWorks等.压缩文件请下载最新的WinRAR软件解压。
2: 本站的文档不包含任何第三方提供的附件图纸等，如果需要附件，请联系上传者。文件的所有权益归上传用户所有。
3.本站RAR压缩包中若带图纸，网页内容里面会有图纸预览，若没有图纸预览就没有图纸。
4. 未经权益所有人同意不得将文件中的内容挪作商业或盈利用途。
5. 人人文库网仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对用户上传分享的文档内容本身不做任何修改或编辑，并不能对任何下载内容负责。
6. 下载文件中如有侵权或不适当内容，请与我们联系，我们立即纠正。
7. 本站不保证下载资源的准确性、安全性和完整性, 同时也不承担用户因使用这些下载资源对自己和他人造成任何形式的伤害或损失。
人人文库网所有资源均是用户自行上传分享，仅供网友学习交流，未经上传用户书面授权，请勿作他用。
川公网安备: 51019002004831号