泵加工专用机床设计—钻4-φ17.5孔组合机床设计【组合机床】
收藏
资源目录
压缩包内文档预览：
编号：122574920
类型：共享资源
大小：3.67MB
格式：ZIP
上传时间：2021-04-20
上传人：221589****qq.com
认证信息
个人认证
李**（实名认证）
湖南
IP属地：湖南
40
积分
- 关 键 词：
-
加工
专用
机床
设计
17.5
组合
- 资源描述：
-
泵加工专用机床设计—钻4-φ17.5孔组合机床设计【组合机床】,加工,专用,机床,设计,17.5,组合
- 内容简介：
-
黄河科技学院毕业设计(文献翻译) 第 16 页 组合机床设计的模块化建模方法图尔加埃萨尔美国密歇根大学研究生研究助理机械工程系杰弗里L斯坦美国密歇根大学机械工程学系卢卡斯卢卡塞浦路斯大学机械与制造工程讲师部摘要在市场需求讯息万变的情况下，为提升工业竞争力，称为组合机床（RMTs）的新一代机床应运而生。为这些机床的高效设计，则须提出新的方法和工具。这是本文提出组合机床伺服轴模块化建模方法的目的，而这也只是努力发展集成的组合机床设计和控制环境的一部分。该机床的组件被模块化，这样就可以将相应的组件基于机床拓扑学装配起来得到任何特定的配置模型。组件模型使用内置的图形代码以促进所需模块库的直接发展。这些机床模块可用于评估，设计和机床伺服轴的控制。这种方法已有实践证明，人们对其优缺也有一定认识。结果表明，该方法是实现自动化和集成的机床设计环境很有希望的一步。人们对完成这个目标所要面对的挑战也进行了探讨。引言不断增长的竞争迫使制造商更快速地响应需求的变化。因此，制造商必须面对产品市场周期短，过渡时期短，型号和量变化频繁的情形，而且不能影响产品质量和成本。作为制造系统的核心，改进的机床在满足上面提到的需求上把握着关键技术。传统的机床在专用和柔性上的缺点今更胜昔：因其设计的重点在单一部件，使专用设备缺乏柔性机床所具备的灵活性和可扩展性。另一方面，柔性机床无法实现鲁棒性，高的成本效益和专用设备所有的生产量水平1。新一代机床在美国密歇根大学工程技术研究中心由Ann Arbor主持开发，为的是克服现有生产系统的不足部分为可重构制造系统而开发。这些机床称为组合机床（RMTs）2，它们结合了专业和灵活的优点。它们围绕一个零件族和他们的结构设计，在硬件和软件方面，可以快速的改变，经济有效地实现精确的功能和满足设备需求 3 。含多种配置，提供所需柔性和可扩展性，RMTs本质上导致了更复杂的机床设计问题。帮助促进RMTs设计的方法和工具将很大的促进可重构制造系统的应用4-6。RMTs设计问题的一个重要方面是发展动态模型的设计，伺服轴的控制和赋值。使RMTs建模问题独特的 是，即使仅有一台机床，也和存在几种不同的配置，且单独的模式，必须开发。为所有可能的配置开发动态模型可能是一个繁琐和费时的任务，即使利用了特别的方法。而且，没有系统的方法建模将需要大量的专业知识，并容易出错，从而降低了设计中使用模型的效率。本文提出了一种方法，可以有助于减少RMTs建模的时间，出错和麻烦。这一方法的核心思想是利用RMTs的模块化结构的优势，采取RMTs模块化建模方法的建模概念。首先，RMTs的物理组件的模块化建模方式是使用键合图建模工具7。该键合图模型被封装在一个定义的连接端口的示意图中。然后，原理组件模型按照给定的配置拓扑来组装获取配置模型。配置模型很容易与非动部件如插补器和控制器结合，这可用条形图方便体现；但是这超出了本文的范围。背景RMTs概念是由科伦和哥打2提出，从那时起，RMTs的设计就是一个活跃的研究领域。设计RMTs4的方法、工具以及评价结构刚度5和提示错误6设计的替代工具已经开发出来。然而，开发一个系统级建模方法的问题还没有解决。传统上，机床模型描绘伺服电机和驱动装置为第一或第二阶系统8,9 。然而，陈和特卢斯季认为一旦采用了高速机床伺服驱动的结构动力可能会影响系统性能 10。许多研究人员认定需要配合结构动力学在高速机床上使用高阶模型，以便能够成功设计其控制系统 11-13。这些论述清楚地表明，机床建模不是一项简单的任务和考虑复杂模型时必须要细心，但他们没有提供系统的建模方法，因此，仍然得应用特殊方法。为有助于设计和控制机床伺服驱动，仍有人努力做自动仿真模型的研究。威尔逊和斯坦开发了一个叫建模助手的软件程序能在一个给定的影响范围内自动创成机床驱动系统微型模型（FROI）14。该模型包括飞轮、一个扭转轴、一滚珠丝杠、一滚珠直流电动机、一个扭转连接键、带驱动和齿轮副的组成部分，其复杂性自动增加，直至超过规定FROI的特征值。这项工作仅是一个概念模型推演法则的证明，不能适用于任何真正的机床系统。不过，这种方法可以用来确定发展系统模型时其复杂性是否适当。戈蒂埃等已经开发出一种名为SICOMAT的软件包（仿真与控制的机床分析），这有助于建模，仿真，模态分析和控制器的一倍或两倍减震或两个机床轴耦合15。他们的模型由大量的模块和弹簧描述机械系统的动态特性。这项工作使得机床的建模过程更加系统，因此对建模工程师来讲是很有价值的工具，但它缺乏RMTs设计方式所要求的普遍性、模块性和柔性。RMTs建模方法如图1显示了所设想的RMTs建模环境。这对于实现RMTs建模任务自动化是理想的，而特定的RMTs的配置模型自动从标准组件模块库组装。这样所有人工或自动产生的候选设计都可以快速模拟，而其模型可用于就它们的伺服轴动态性能和帮助设计方面评价候选方案，如图一所示，模块化组件模型库是一个自动的RMT建模环境的重要组成部分。因此，拟议方式的第一步就是为了开发用于生成RMT配置组件的标准模型。本文将重点放在机械零件上，并讨论了它们模块化的建模方法。因为机械部件之间相互影响，促成它们的模块化,更有趣的造型。只交流如插补器和控制器信号的模块化建模的组件，提出了一种比较简单的问题，这儿不再讨论。为促进模块化和使组件与环境之间的能量交流更容易，键合图被作为了建模语言。键合图提供电力的物理系统的图形表示。此外，键合图用统一的方式描述了不同的能源领域，这对RMTs建模是相应的优势，因为他们的伺服轴可能包括来自不同领域如机械、电气或液压的组件。键合图只是用在这项工作中模型体现分级结构中的一级。键合图下一水平的数学方程式代表键合图体现的物理现象，这种数学体现只是层次结构中的最低水平。最高级别的键合图都被封装在一个示意图中，这不仅表现紧凑，而且还显示与环境融合的连接端口。图2说明了这种层次模式体现。这篇论文所有的模型显示在原理层次，因为本文的目的不是讨论他们的来历，而是想一旦得到这些模型能够做些什么。本文所用模型的详细描述在16中都可以找到。为了能够应付任何经历不同配置的机械部件的空间运动，使用了捕捉三维动态的模型。此外，最初的假设是，在机械领域范围内所有组成部分都可作为刚体充分体现。图3所示的有N连接端口的一般刚体是模块库中的一个主要模块。对应于刚体上兴趣点的端口，与环境发生物理上的交互。关系用于指示端口是原子端口，如主要部分能通过端口与所处环境交换能量。而现行的关系则指出了信号端口。只有信息通过这些端口传输。模型库还包含三维连接模块可用于描述构件模型的相关运动。这些联合模块和端口也以标准开发，这样他们可以连接到其他模型模块。该库提供了两种方法来表达制约因素：（1）硬的弹簧和减震器可以用来实现更现实的限制，或近似理想的限制；（2）拉格朗日乘数可以引进来表达理想约束。对于联合模块的论述读者也被称为16。一旦模型库由一些基本的模块化刚体和模型组建，建模过程可以进行如下：RMT构件被分解成单件，每个单件与库中的模型相关。如果库中的模型模块都不能完全描述这个单件，那么必须开发一个新的相关模块并添加到库中。然后，模型根据构件拓扑并使用必要的结合块组装。一旦获得组件模型，它可以存储在库中备用。最后，组件模型按照给定的配置拓扑获得该配置模型的组装。这个过程可以用图4的流程图及以下部分的例子给予证明。实例下面两个例子给提议的建模方法一个概述。第一个例子显示了一个幻灯片建模和第二个例子采用该幻灯片模式发展为RMTs模式。这些例子的目的是提供一个关于组件的模块化如何用在建模流程中的总体思路，而不是解释每个（子）组件如何识别和建模的详细信息。因此，该模型模块的细节如它们的复杂程度都没有讨论。滑动体建模是大多数机床工具基本组成部分，包括RMTs。不同的RMTs配置可以通过添加/删除滑动体获得或重新配置现有结构中的滑动体。因此演示一个滑动体建模流程是有益的。参看图5所示的滑动体。这是假设的构成部分即如图所示。本示例的目的，所有除电机外的子构件可以像刚体与各连接点样建模。电动机的动力可分为两个用途：三维架构刚体动力和驱动转子和定子之间旋转运动的机电动力。电动机获取双领域动力的模型也已经开发出来，其示意图由图6给出。弓形RMT的模型是由美国国家科学基金会工程研究中心可重构制造系统在密歇根大学开发的，是世界上第一个完整规模的RMTs。这是一个3轴机床，其设计围绕着具有五个不同表面族，这些表面倾角变化范围从-15 至45 ，一次增量15 。它还具有如磨削、钻削加工任意角度的柔性。弓形RMT的可重构性来自于主轴单元，它可通过弓形模块的弯曲导向槽移动从而在上面提到的5个角度得到配置，然后在任意一个位子上由机械挡块固定。为了举例假设基本模块是完全相同的，并对机床没有动力的影响。该工作台、圆柱、主轴基本上都是滑动体，其模型都以上述滑动体模型为基础。该拱被建模为刚体并带有与每个机械挡块连接的端口。最后，该拱式RMT模型按实际机器的拓扑结构组装。要注意这个数字显示的模型只是配置之一。其他配置的模型可通过改变拱模型连接端口得到。既然模型已组装，运动方程可以自动从图形模式得出，并执行仿真。尽管数学模型准备好了，由于当前缺乏好的系统参数估计，我们不能在本文中提供任何仿真结果。一旦参数值可用仿真就很容易进行。讨论本文中标准建模和分级建模概念被确定为RMTs建模方法的主要特点。RMTs的模块化结构使这种建模方法很有益处，因为这些模型包含了所有可重构的重要特征17：1模块化：（子）组件建模模块化2可集成：该模块可以通过其连接端口与其他模块集成3定制：详细程度包括了模型模块都可为单个组件进行定制4可重构性：模型可以很容易地从一个配置转换到另一个5诊断性：可方便地进行模块的模型验证本文介绍的方法可以将建模任务分为两个步骤：（1）开发组件模型；（2）装配配置模型。虽然第一步仍然需要大量的建模知识，第二步更系统，甚至将来要实现自动化。此外，两个步骤各有侧重：第一步的重点是组件内动态，而第二个步骤重点是组件之间的动态。相对于伺服轴建模现有的方法，各个不同的RMTs配置都是一个潜在的新建模问题，本文提出的方法允许配置模式更快的发展。配置可以使用库中的模型模块快速组装，假若如此，使用在给定配置的所有组件在模库中都有对应的模块。因此，一个完善的模型库对这一方法的有效性是必不可少的。对机床的机械部件三维多体建模方法推动了机械领域的模块化。因此，机床滑动模型可用于任何配置，例如在一个滑台移动有更多约束的环境下而不需要特别的滑台模型。以多体的方法，开发通用组件模型可以没有组件接口的先验知识。然而三维多体方法的一个缺点是通用模型可能比某一实际配置的需求更复杂。例如，在给定的配置中一个组件可能只是被限制在一个平面运动中，在这种情况下，三维模型就过复杂了。该模型应该简化，否则模型中不必要的复杂性降低了模型的计算效率。拟议的模块化建模方法将从集成模型降阶算法中受益。这将是今后工作的重点。目前，该机构被认为是刚性，这并不总是很接近。为了能够研究结构动力学的影响，柔性的机构模式也应开发并添加到模库内。最后，值得注意的是商业可用软件包如ADAMS,、DADS、 EASY5、 Dymola 等也可用于RMTs建模的目的。然而，采取统一强大的键合图提供的功能基础方法，并简化未来的模式使其更易于实施，那么键合图就被选为建模语言。概要和结论模块化建模方法被提议作为组合机床建模方法。这些部件在标准方式下建模，这么做的目的就是为了在组建给定的机床配置模型时只需将相应的模块组装就可以了。本文给出了两个例子来说明这种方法，并且讨论了这种方法的优劣。这项工作的结果表明，RMTs的模块化建模问题可以使建模过程系统化，这样对于在职工程师来讲要获得自动的设计建模环境有潜在的用处。但是如在讨论中所强调的那样，仍然有很多挑战需要在自动化建模环境切实执行之前落实。致谢这项工作是在欧洲经济共同体9529125授权下由国家科学基金会可重构制造系统工程技术研究中心支持的。A MODULAR MODELING APPROACH FOR THE DESIGN OF RECONFIGURABLE MACHINE TOOLSTulga ErsalGraduate Student Research Assistant Department of Mechanical Engineering University of MichiganJeffrey L. SteinProfessor Department of Mechanical Engineering University of MichiganLoucas . LoucaLecturer Department of Mechanical and Manufacturing Engineering University of CyprusABSTRACTA new generation of machine tools called Reconfigurable Machine Tools (RMTs) is emerging as a means for industry to be more competitive in a market that experiences frequent changes in demand. New methodologies and tools are necessary for the efficient design of these machine tools. It is the purpose of this paper to present a modular approach for RMT servo axis modeling, which is part of a larger effort to develop an integrated RMT design and control environment. The components of the machine tool are modeled in a modular way, such that the model of any given configuration can be obtained by assembling the corresponding component models together based on the topology of the machine. The component models are built using the bond graph language that enables the straightforward development of the required modular library. These machine tool models can be used for the evaluation, design and control of the RMT servo axes. The approach is demonstrated through examples, and the benefits and drawbacks of this approach are discussed. The results show that the proposed approach is a promising step towards an automated and integrated RMT design environment, and the challenges in order to complete this goal are discussed. INTRODUCTIONThe ever-growing competition forces manufacturers to respond more quickly to changes in demand. As a result, manufacturers have to deal with short product life cycles, short ramp-up times and frequent changes in product mix and volumes, without compromising product quality and cost.Being the heart of a manufacturing system, improved machine tools hold the key in meeting the above mentioned requirements. The shortcomings of conventional machine tools, which can be classified as dedicated and flexible, are being felt more today than in the past: With their design focus being a single part, dedicated machines lack the flexibility and scalability that the flexible machines offer. On the other hand, flexible machines cannot achieve the robustness, the cost-effectiveness and the throughput levels of dedicated machines1. A new generation of machine tools is being developed in the Engineering Research CenterforReconfigurable Manufacturing Systems at the University of Michigan, Ann Arbor, as part of an effort to overcome the insufficiencies of current manufacturing systems. These machine tools are called Reconfigurable Machine Tools (RMTs) 2, and they combine the advantages of their dedicated and flexible counterparts. They are designed around a part family and their structure, in terms of both hardware and software, can be changed quickly and cost-effectively to achieve the exact functionality and capacity desired 3. Containing several configurations to provide the needed flexibility and scalability, RMTs intrinsically lead to more complex machine tool design problems. Methodologies and tools that would help facilitate the design of RMTs could highly benefit and encourage the employment of reconfigurable manufacturing systems 4-6. One important aspect of the RMT design problem is developing dynamic models for the design, evaluation and control of servo axes. What makes the problem of modeling RMTs unique is that even though there is a single machine tool, there exist several configurations, which separate models have to be developed for. Developing dynamic models for all possible configurations could be a cumbersome and time-consuming task if ad hoc methods are utilized. Moreover, without a systematic methodology modeling would require a lot of expertise and would be prone to errors, which would degrade the efficiency of using models in the design.In this paper we present a methodology that could help make the RMT modeling task less time demanding, less error-prone and less challenging. The key idea of this methodology is to take advantage of the modular structure of the RMTs and adopt modular modeling concepts into the RMT modeling methodology. First, the physical components of an RMT are modeled in a modular way using the bond graph modeling tool 7. The bond graph model is encapsulated in a schematic representation with defined connection ports. Then, the schematic component models are assembled by following the topology of a given configuration to obtain the model of the configuration. The configuration model can be easily integrated with the modules of non-energetic components such as interpolators and controllers, which can be conveniently represented with block diagrams; however this is beyond the scope of this paper. BACKGROUNDThe RMT concept was introduced by Koren and Kota 2, and since their introduction, the design of RMTs has been an active research area. Methodologies and tools for designing RMTs 4 as well as evaluating structural stiffnesses 5 and tool tip errors 6 of de sign alternatives have been developed. However, the problem of developing a system level modeling methodology for RTMs has not been addressed yet. Traditionally, machine tool models depict the machine tool as a group of servomotor and feed drive assemblies that aremodeled as first or second order systems 8,9. Chen and Tlusty, however, showed that the structural dynamics of the feed drive could affect the system performance once high-speed machine tools are considered 10. Many researchers identified the necessity to use higher order models for high-speed machine tools to cope with structural dynamics in order to be able to design the control system successfully 11-13.These publications clearly indicate that modeling a machine tool is not a trivial task and care must be taken when deciding on the complexity of the model, but they do not provide a systematic way of modeling and, therefore, remain application specific approaches.There have been research efforts to help the design and control of machine tool feed drives by automatically providing simulation models. Wilson and Stein developed a software program called Model-Building Assistant to automatically synthesize a minimum order model of the machine tool drive system for a given frequency range of interest (FROI) 14. The complexity of the model, which includes a flywheel, a torsional shaft, a ballscrew , a ballnut, a DC motor, a torsional coupling, a belt-drive and a gear-pair as components, is automatically increased until the eigenvalues of the system fall beyond the specified FROI. This work was a proof of concept for a model deduction algorithm and can not be applied to any real machine tool system. However, such algorithm can be used to determine the appropriate model complexity after the development of the system model.Gautier et al. have developed a software package called SICOMAT (Simulation and Control analysis of Machine Tools) which helps with the modeling, simulation, modal analysis and controller tuning of one or two decoupled or two coupled machine tool axes 15. Their models describe the dynamics of the mechanical system by a number of masses and springs. This work makes the modeling of a machine tool process more systematic, and is therefore a valuable tool to the modeling engineer; however, it lacks the generality, modularity and flexibility that the RMT design methodology demands. The RMT modeling methodology Figure1 showstheenvisioned RMT modeling environment. It is desired to automate the task of RMT modeling, where the model of a given RMT configuration is automatically assembled from a library of modular component models. This way, all the candidate designs, which are generated either manually or automatically 4, can be modeled quickly and the models can be used to evaluate the candidates in terms of their servo axis dynamic performance and help with their design. As Figure1 also implies, the modular component model library is a key part for the automated RMT modeling environment. Therefore, the first step of the proposed methodology is to develop modular models for the components that are used to generate the RMT configurations. This paper puts the emphasis on mechanical parts and discusses their modeling in a modular way, because the energy interaction between the mechanical components makes their modular modeling more intriguing. Modular modeling of components that only exchange signals, e.g. interpolators and controllers, presents a relatively simpler problem and are not discussed here. To promote modularity and to be able to deal with the energy interactions between the components and their environment rather easily, bond graphs are utilized as the modeling language. Bond graphs provide a power-based graphical representation of a physical system. Moreover, bond graphs describe different energy domains in a unified way, which is a relevant advantage for RMT modeling, since their servo axes may include components from different energy domains, such as mechanical, electrical or hydraulic. Bond graphs are only one level in the hierarchy of model representations used in this work. Underneath the bond graph level the mathematical equations represent the physical phenomena captured by the bond graph and this mathematical representation is the lowest level in the hierarchy. In the highest level bond graphs are encapsulated in a schematic representation, which not only allows for a compact representation, but also shows the connection ports where the model can interact with its environment. Figure 2 illustrates this hierarchy of model representations.In this paper all the models are shown in the schematic level, because the goal of this paper is not to discuss their derivation, but rather to show what can be done once those models are obtained. A detailed description of the models used in this paper can be found in 16.In order to be able to cope with any spatial motion that the mechanical components may go through in different configurations, models that capture the three-dimensional dynamics are used. Moreover, the initial assumption is made that in the mechanical domain all components can be adequately represented as rigid bodies.Figure 3 shows the schematic representation of a generic rigid body with N connection ports, which is one of the main model modules in the library. The ports correspond to points of interest on the rigid body, where the physical interactions with the environment occur. Bonds (lines with half arrows) are used to indicate that a port is a power port, i.e. the body can exchange energy with its environment through those ports, whereas active bonds (lines with full arrows) indicate signal ports, i.e. only information is transferred through these ports. The model library also contains three-dimensional joint models that can be used to describe the relative motions between the component models. These joint models are also developed in a modular way with ports, where they can be connected to other model modules. The library offers two ways to express the constraints: (1) stiff springs and dampers can be used to implement more realistic constraints or to approximate ideal constraints;(2) Lagrange multipliers can be introduced to express the constraints ideally. For a discussion of joint models the reader is also referred to 16.Once the model library is populated with some basic modular rigid body and joint models, the modeling procedure can be carried out as follows: The RMT components are broken down into subcomponents and each subcomponent is associated with a model in the library. If none of the model modules in the library can describe the subcomponent adequately, a new model has to be developed for that subcomponent and added to the library. Then, the models are assembled by following the topology of the components and using the necessary joint models. Once a component model is obtained, it can be stored in the library for reuse. Finally, the component models are assembled by following the topology of a given configuration to obtain the model of that configuration. The process is illustrated in Figure 4 as a flowchart and demonstrated in the following section through examples.EXAMPLESThe following two examples give an overview of the proposed modeling methodology. The first example shows the modeling of a slide and the second example employs that slide model to develop a model for a RMT. The purpose of these examples is to give a general idea about how the modularity of the components can be exploited in the modeling procedure, rather than to explain the details of how each (sub)component can be identified and modeled. Therefore, the details of the model modules, such as their level of complexity, are not discussed.Modeling a Slide A slide is a basic component of most machine tools, including RMTs. Different RMT configurations can beobtained by adding/removing slides to/from the configuration or by rearranging the existing slides in the configuration. Therefore, it is useful to demonstrate the modeling procedure of a slide. Consider the slide shown in Figure 5. It is assumed that the components are identified as shown in the figure. For the purposes of this example, all the subcomponents except the motor can be modeled as rigid bodies with various number of connection points. The motor dynamics can be broken down into two domains: the three-dimensional rigid body dynamics of the housing and the electromechanical dynamics that drive the relative rotational motion between the rotor and the stator. A model has been developed for the motor that captures the dynamics in both domains and its schematic representation is given in Figure 6.Modeling the Arch-type RMT, which was developed by the NSF Engineering Research CenterforReconfigurable Manufacturing Systems at the University of Michigan, is the worlds first full scale RMT. It is a three-axis machine tool that is designed around a part family with five different surface inclinations ranging from -15 to 45 at 15 increments and has the flexibility of doing machining operations such as milling and drilling at any of those angles. The reconfigurability of the Arch-type RMT comes from the spindle unit, which can be configured at the five angles mentioned above by moving it along the curved guide way of the arch module and fixing it at any of the five locations on the arch module that are defined by mechanical stops. For the purposes of this example the base module is assumed to be identical to the ground and it has no effect on the dynamics of the machine tool. The worktable, the column and the spindle are essentially slides and their models are based on the slide model given above. The arch is modeled as a rigid-body with a connection port for each mechanical stop. Finally, the model of the Arch-type RMT is assembled by following the topology of the actual machine. Note that the figure shows the model for one of the configurations only. The models for the other configurations can be obtained by changing the connection port of the arch model. Now that the model is assembled, the equations of motion can be derived from the graphical model automatically, and simulations can be performed. Although the mathematical model is ready, we cannot provide any simulation results in this paper due to the current lack of good estimates of system parameters. Simulations can be carried out easily once the parameter values are available.DISCUSSIONIn this paper, modular and hierarchical modeling concepts are identified as the key characteristics of the RMT modeling methodology. The modular structure of RMTs makes this modeling approach beneficial, because the models contain all the key characteristics of reconfigurability 17:1.Modularity: The (sub)components are modeled in a modular way 2.Integrability: The models can be integrated with other modules through their connection ports 3.Customization: The level of detail included in the model modules can be customized for individual components4.Convertibility: Models can be easily converted from one configuration to another 5.Diagnosability: Model verification can be carried out easily on model modulesThe approach presented in this paper allows for the separation of the modeling task into two steps:(1) Developing component models;(2) assembling the configuration model. While the first step still requires a significant modeling expertise, the second step is much more systematic, and can even be automated, which is left as a future work. Also, the two steps have different focuses: The first step focuses on the dynamics within a component, whereas the second step focuses on the dynamics between the components.Compared to the existing approaches of servo axis modeling, where every different RMT configuration would potentially be a new modeling problem, the approach presented in this paper allows for a faster development of configuration models. Configurations can be assembled quickly using the model modules in the library, provided that all the components utilized in a given configuration have a corresponding model module in the library. Therefore, having a comprehensive model library is essential for this methodology to be efficient.A three-dimensional multibody approach to modeling the mechanical components of the machine tool promotes modularity in the mechanical domain. Thus, for example, the model of the machine tool slide can be used in any configuration without having a special slide model for circumstances where the base of the slide is constrained to move in more restricted ways. With a multibody approach, generic component models can be created without a-priori knowledge of the connectivity of the components. A drawback of the three-dimensional multibody approach is, however, that the generic models might be more complex than a certain configuration actually demands. For example, in a given configuration a component can be limited to a planar motion only, in which case a three-dimensional model would be overcomplex. The model should be simplified; otherwise unnecessary complexity is retained in the model and reduces the computational efficiency of the model. The proposed modular modeling methodology would benefit from the integration with a model order reduction algorithm. This will be the focus of future work.Currently the bodies are considered rigid, which is not always an adequate approximation. In order to be able to study the effects of the structural dynamics, flexible body models should also be developed and included in the library. Finally, it is worthwhile to note that commercially available software packages, such as ADAMS, DADS, EASY5, Dymola etc, could also be used for the purposes of RMT modeling. However, to take advantage of the unified powerbased approach that the bond graphs provide and to make a future model reduction easier to implement, bond graphs are chosen as the modeling language.SUMMARY AND CONCLUSIONS A modular modeling approach is proposed as a RMT modeling methodology. The components are modeled in a modular way, so that the modeling task of a given RMT configuration merely involves assembling the corresponding model modules together. Two examples are given to illustrate the methodology, and advantages and disadvantages of this approach are discussed. The outcomes of this work indicate that a modular approach to the problem of modeling RMTs can make the modeling process systematic and thus potentially more useful to practicing engineers if implemented in an automated modeling and design environment. However, there are still challenges, as highlighted in the discussion, that need to be addressed before an automated modeling environment can be implemented in a practical way. ACKNOWLEDGMENTSThis work was supported by the Engineering Research Center for Reconfigurable Manufacturing Systems of the National Science Foundation under Award Number EEC 9529125.REFERENCES1 Mehrabi, M. G. and Ulsoy, A. G., 1997, State-of-the-Art in Reconfigurable Machining Systems, ERC/RMS Technical Report, University of Michigan, Ann Arbor2 Koren, Y. an
- 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