机械专业英文翻译.换档杆壳钻纵孔专机设计

1、 Nanjing University of Technology毕业设计（论文）英文译文学生姓名： 成 干 学 号： 2507030101 所在学院： 技术学院 专 业： 机械设计制造及其自动化 设计题目： 换档杆壳钻纵孔专机（Y）设计 指导教师： 夏 海 南 翻译题名：Knowledge model as an integral way to reuse the knowledge for fixture design process（基于夹具设计过程的整体知识模型）(英文原文见附后)期刊与作者：R. Hunter Journal of Materials Processing Techn

2、ology 128（2002）7-18：15101515出版社： Elsevier Science B.V.l 英文译文：摘要： 夹具设计因其涉及到几何，公差，尺寸，加工，制造资源等诸多不同领域的知识，而被公认为是项复杂的研究。如今，夹具设计过程在知识模型的基础上已经适应了自动化系统的需要。这些实施于夹具设计过程中的知识模型描述了物理原理和推理过程的特性和关联。由于加入了知识模型和自动控制，夹具的设计过程将更趋于系统化，结构化。 基于知识模板这种具体方法的使用，将其应用到不同设计过程中去很具可行性。知识模型向我们详细描述了设计过程中的普通实体和推论过程。 在知识模型的应用方面，我们建议不仅可用

3、于机床夹具的设计过程中，还可应用于检测，组合，定位焊接等其它类型夹具。 © 版权所有 Elsevier B.V. 2005 关键词：知识模型，知识模板，夹具设计1 绪论 人们对于将知识表达应用于描述和捕获设计制造系统知识的潜心研究从未停止过13。这样，知识模型就作为一种工具来帮助我们阐明精深知识的结构，以及进行信息处理工作。从这一意义上看，通过系统的学习，知识模型可以为我们提供所必需的数据说明和过程推论4。亨特第一个提出了将知识模型应用于机床夹具设计过程中的理念5。在过去十年里，建模技术广泛应用于诸如加工，组合，检测等制造过程的夹具设计过程中6。基于夹具设计过程的复杂性和广泛性，各种

4、不同的研究部门都集中在这种过程的特殊活跃性研究上，如：夹具构造，公差分析，稳定性和可达性。对于如何将知识应用到夹具设计过程中，科学家们做了大量的研究。这些研究都集中在夹具设计过程中所使用的设计参数，夹具结构，夹具原理描述等方面2，7。根据夹具设计中知识的应用情况，可分为人工智能技术方面的应用8，9和设计系统的自动控制应用两大方面2。不管是哪方面的应用，将知识模型应用于夹具设计系统都具十分重要的作用。具体体现在如下方面：需将具体概念应用于夹具设计中；需建立知识库系统（KBS）；最后，还要将知识和概念基础相结合。在此意义上，结合实体和结构描述于一体的知识模型应用于机床夹具设计过程中，即产生一种新的

5、模板，可将其应用到检测夹具和组合夹具的设计过程中。在知识模板中已加入了这种实体和结构描述想结合的方法4。图1 工作结构图此项工作为我们呈现了将知识模型应用于机床夹具设计中的详尽建议，图1向我们展示了将知识体应用到检测夹具设计过程总图。2 夹具设计过程知识模型的现状 夹具概念源于工件和刀具，工件和机床间建立理论联系的需要。这一联系需满足实现加工过程的需要。夹具主要功用是将工件支撑，定位，夹紧在机床上。为了正确描述夹具设计过程中所需知识的重要性，很有必要明确这一过程的基本信息，见表1。 所有这些基本信息都描述了夹具设计过程中知识模型各个部分的实体和关联。各模型的定义有助于我们更好的了解设计系统中知

6、识体系的捕获，描述和使用，例如MOKA和Common KADS方法。 MOKA方法基于两种典型。这些典型可以捕获，构造知识体系。第一种体系，用一系列窗体（ICARE：图解，约束，行为，规则，实体）来捕获，描述知识，是一种半结构化的方法；第二种体系，使用统一建模语言来描述知识，是一种结构化的方法10。Common KADS方法提出了使用刀具和技术来捕获，构造知识体系。就使用知识体而言，Common KADS方法提出了使用知识模板的概念：所谓知识模板就是知识模型的一部分，它可以将相关数据和推理过程结合到其它应用软件中去。表1 机床夹具知识体 知识体 特性 工件几何学 几何学：孔，槽等，尺寸，公差

7、加工工艺 加工工艺类型加工阶段和初加工阶段加工操作 夹具设计过程的细节和功用 设计方法设计规则解释规则设计局限 夹具资源（功能元素 夹具类型（标准件，普通件，专用件） 和商业元素） 夹具元素类型（支撑，定位，夹紧等） 机床类型（立式铣床，卧式铣床等）3知识模型形成的方法论：结构模型知识模型方法论的实现需要经历两个阶段。第一阶段描述了诸如工件几何，加工工艺，夹具设计的功能和细节，夹具资源等实体知识（见表1）。第二阶段描述了机床夹具所需解决的首要问题相关过程（设计和解释规则）。这两个阶段描述了机床夹具知识模型的两个组成部分：实物的结构模型和行为模型。机床夹具设计过程更为集中在结构模型的描述上。结构

8、模型包含了夹具设计过程中相关的整体知识结构。表1描述了知识体的各个相关方面。图2展示了机床夹具设计过程中知识体的整体框架。基于夹具设计过程的复杂性，夹具设计不能脱离加工过程而独立存在。在此意义上，加工工艺与夹具设计过程有着直接的联系。同样，就机床和夹具设计的商业元素而言，加工工艺与夹具资源间也有着相当微妙的 关系。 各知识体间的定义（见表1）考虑了与这些知识体相关知识的特性图2 机床夹具的结构模型 和必要操作。这些模型应用与下面各部分中。4知识模板 在这一部分，描述了知识模型使用知识模板的方法用于其它应用软件中。从概念上讲，知识模板描述了知识模型的一部分在应用软件中的使用。在此意义上，很有必要

9、区分分析任务和综合任务。分析任务描述了夹具设计过程中实体的分类；综合任务则描述了夹具解决方案间的相互联系。图3 基于结构模型的知识任务通过分析和综合任务这两种类型任务的使用，建立了知识体的分类。图3展示了用分析和综合任务来描述机床夹具设计过程的结构模型。 这两种任务的区分，建立了知识体的第一标准，既实体及特征可用于新发展的应用软件中。两种类型任务的区分还描述了设计过程中的推论过程，夹具功能设计，夹具设计细节等。这一部分指出知识模型的分类是在分析和综合任务下用于其它应用软件中去的。41分析任务的概念 在此范畴中实体的分类是基于机床夹具设计的发展标准。第一标准描述了夹具设计过程如：工件几何，尺寸，

10、公差等与知识体间并无因果关系。在这一标准中，组成这些实物的知识体完全可运用到它们的结构，关联特性中。图4就是一个将几何知识体用于其它应用软件中的例子。图4 工件实体的知识模板（分析任务）第二标准描述了夹具设计过程中实体间相似的结构和关联（机床夹具的功能）。这一标准并不是夹具设计过程的必要条件，仅能用于部分结构和关联中。第三标准描述了这些实体完全依赖于夹具设计过程。基于这一标准依赖于过程的发展情况，故不能用于已定义的知识体中（如：结构，关联，特征）。42综合任务概念 综合任务包括实物辨析和推论程序两方面。在这类任务中，由于推论过程要根据过程处理的不同来使用不同的加工规则，故不能完全根据知识体来确

11、定。图5 功能元件实体的知识模板根据分类，功能设计的知识体建立了夹具概念的功能方法：找支撑面，定位，夹紧工件。支撑面根据加工过程的发展来定义。这一特性决定了加工工件的整个过程中，设计过程都要基于加工过程。从此意义上看，知识体的共享会因定位面，定位点，方位，夹具的夹紧和功能元件的选择而受到限制。但由于功能元件可用于夹具设计过程中的多范畴领域，所以也可用于其它应用软件中。图5是将功能元件的知识模板用于夹具设计过程的例子。 样图设计和功能设计相似。样图设计是在功能设计的基础上加入了相应的功能和商业元素。为此，我们运用结构，关联和实体来定义了下列种类，基体，支撑，定位，夹紧和辅助元件。表2 夹具设计的

12、初始信息信息 特性初始几何学 最终几何学 加工操作 端面铣削 边铣 钻削 加工资源 立式铣床 夹具资源 标准夹具单元5知识模型的应用 以下两部分描述了加工和检测夹具设计中知识模型的应用。根据其使用潜能，这些模型分为不同的两类。 第3部分中关于结构模型的阐述，是基于构成这些模型知识体的实例特性。为此，包括初始及最终几何学的描述，加工工艺图，机床和夹具资源在内的初始信息都应用于知识模型中。表2就列出了应用于其中的初始信息。【附】英文原文翻译题名：Knowledge model as an integral way to reuse the knowledge for fixture design

13、process期刊与作者：R. Hunter Journal of Materials Processing Technology 128（2002）7-18：15101515出版社： Elsevier Science B.V.AbstractThe fixture design is considered a complex process that demands the knowledge of different areas, such as geometry, tolerances, dimensions, processes and manufacturing resources.

14、 Nowadays, the fixture design process is o-riented to automated systems based on knowledge models. These models describe the characteristics and relationships of the physical elements together withthe inference processes that allow carrying out the activity of fixture design. With the employment of

15、the knowledge models, besides the automation, it ispossible to systematize and structure the knowledge of the fixture design process.With the use of specific methodologies, as the knowledge template, it ispossible to reuse the knowledge represented in a model, for its use in a different design proce

16、ss. The knowledge template represents a pattern that defines the common entities and inference processes to use in the design process .In this work, with the use of knowledge template we propose the reuse of the knowledge described in the design process of fixtures for machining to other types of fi

17、xtures uses like inspection, assembly or welding.© 2005 Elsevier B.V. All rights reserved.Keywords: Knowledge model; Knowledge template; Fixture design1. IntroductionThe continuous challenge that involves the knowledge representation hasoriented to many different research groups to develop meth

18、odologies that describe stages for capture and representation of the knowledge in design and manufacturing systems 13. This has allowed to define knowledge models as a tool that helps us to clarify the structure of intensive knowledge and information-processing tasks. In this sense, a knowledge mode

19、l provides a specification of the data and inference processes required by the system of study 4. A first approach in the development of knowledge models applied to machining fixtures design process has been proposed by Hunter 5.During the last decade, the use of modelling techniques has allowed ust

20、o represent the fixture design process employed in some manufacturing operations, such as machining, assembly and inspection, etc. 6. Due to the complexity and the wide scope of the fixture design process, different researchgroups have been focused in the analysis of specific activities of this proc

21、ess,such as fixture configuration, tolerance analyses, stability and accessibility.A great number of investigations has taken in consideration the way inwhich represent the knowledge used in the fixture design process. These researches are focused in the documentation of the design parameters, the s

22、tructuring of the information of the fixture and the description of the fixture elements used in fixture design 2,7. On the other hand, the implementation of the knowledge used in the fixture design can be classified regarding the artificial intelligence technique(AI) used 8,9 and on the automation

23、level of t-he design system2.However, whatever it is the artificial intelligence technique used and the automation level of this type of systems, the process of knowledge modelling in the fixture design is important for several reasons: the need to specify the concepts used in the fixture design; to

24、 establish the relationships amongdifferent knowledge groups; to develop knowledge based systems (KBS), and finally, to provide a conceptual base for reusing the knowledge. In this sense, the entities and structures defined in a knowledge model for design process of machining fixtures can be partial

25、ly reused to develop new models for fixture design process, as the inspection or assembly fixture. The entities and structures reused has been defined using the method of knowledge template4.The work presented is a detailed proposition of the knowledge model for machining fixture design and the defi

26、nition of the knowledge groups that can be reused in the inspection fixture design process, using the knowledge template method. Fig. 1 presents a general view of the contents of this ex Fig. 1. The structure of the work. planation.2. Present state of fixture design process knowledge modellingThe fi

27、xture concept arises from the need to establish a physical connection between part, and tool, and part and machine-tool. This connection should fulfil some requirements for support the machining operation to carry out. The mainly functionality of the fixture is to support, locate and clamp the part

28、to the machine tool. However, in order to interpreting correctly the needed knowledge for develop the fixture design process, it is necessary to define the basic information related with this process according to the classification exposed in Table 1.All this information has been represented in mode

29、ls that describe the entities, attributes and relationships between each knowledge group in the fixture design process. The definition of these models can be carried out using methodologies that describe the activities to capture, represent and reuse the knowledge of a design system, for example MOK

30、A and CommonKADS.The MOKA methodology is based on the definition of two models.These models allow to capture and to structure the knowledge of a system. The first model, uses a group of forms (ICARE: Illustrations, Constraints, Activities, Rules,Entities) that allow to capture and to represent the k

31、nowledge in a semistructured way; the second model allows to represent knowledge ina structured way, using the extension of UML 10.The CommonKADS methodology proposes the use of tools and techniques to carry out the capture and representation of the knowledge. In the case of reusing knowledge, Commo

32、nKADS proposes the use of the knowledgetemplate: a knowledge template is a piece of a knowledge model, in which the data and reasoning processes can be employed in the development of other applications 3.3. Methodology for development a knowledge model: structural modelThe methodology proposed for d

33、evelopment of a knowledge model includes the realization of two stages. The first stage represents the knowledgeof the objects like part geometry, machining process, functional and detailed fixture design,and fixture resources (see Table 1). The second stage describesthe inference process (design an

34、d interpretation rules) needed to obtain a firstsolution for the machining fixture. These two stages allow to describe the structural model and behaviour model of the objects that compose the knowledge model for machining fixtures. This work is focused mainly in the descriptionof the structural mode

35、l for machining fixture design process. Table 1Knowledge group for machining fixtureKnowledge group CharacteristicsPart geometry Geometry: holes, slots, etc.DimensionsTolerancesMachining process Type of machining processMachining phase and sub phaseMachining operationFunctional and detailed Methodol

36、ogy of designfixture design process Design rulesInterpretation rulesDesign constrainsFixture resources Type of fixture (modular, general, or dedicated)(functional elements Type of fixture elements (support, locate, clamp)and commercial elements) Type of machine tool (vertical milling machine, horizo

37、ntal milling machine, etc.)The proposed structural model contains a general structure of the knowledge groups related with the fixture design process. The description of theaspects related with the knowledge groups are presented in Table 1. Fig. 2 shows the general structure of the knowledge groups

38、for machining fixture design process. Due to the complexity of the fixture design process, the fixture design cannot be considered as an independent process with respect to the manufacturing process. In this sense, the information of the manufacturing process isdirectly represented in the fixture de

39、sign process. In a similarway, the resources involved in the manufacturing process have a narrow relationship with the fixture resources, in terms of machine tools and commercial elements of fixture. The definition of each knowledge groups (see Table 1) has taken intoconsideration the attributes and

40、 necessary operations to represent the knowledge relative to these knowledge groups. The applications of these models are presented in the following sections.Fig. 2. Structural model for machining fixture.4. Knowledge template modelIn this section, we describe those pieces of the knowledge model tha

41、tcan be reused in other applications using the method of knowledge template.From a conceptual point of view, a knowledge template describes a piece of the knowledge model in which the inference and the knowledge tasks are defined with the objective of reuse this knowledge in other similar applicatio

42、ns. In this sense, it is necessary to distinguish among the analytic and the synthetic tasks. The analytic tasks define the classification of the objects involvFig. 3. Knowledge tasks based on the structural model.ed in the fixture design process. The synthetic tasks have relationship with the reaso

43、ning way procedure from which a fixture solution is obtained.Using these two types of tasks, a first approach has been established to define the knowledge groups that can be classified under the analytic and synthetic tasks. Fig. 3 shows the objects of the structural model that describe the analytic

44、 and synthetic tasks of the machining fixture design process.The division of these two tasks allows to set in a first level the knowledge groups, that it objects and attributes that can be employed in the development of new applications. Also, this separation allows us to identify those knowledge gr

45、oups that describe inference procedures in the design process,as the functional fixture design and the detailed fixture design. This section presentsthe definition of the tasks of the knowledge model classified under theconcept of analytic and synthetic tasks that can be reused in other applications

46、.4.1. Analytic task definitionThe entities (or classes) defined under this category can be classified regarding the level of dependence level that present the objects involved in the machining fixture design. The first level defines those knowledge groups that are not consequence of the fixture desi

47、gn process, as geometry, dimensions and tolerances of the part. In this level, the entities that compose these knowledge groups can be totally reused in their structure, relationships and attributes. Fig. 4 shows an example of the knowledge group of geometry that can be reused in other applications.

48、Fig. 4. Knowledge template for part entity (analytic task).The second level describes those entities that present a similar structure and relationships in the fixture design process(fixture functions and commercial elements for machining fixtures). In this level, can be reused only a portion of the

49、structure and relationships that are not conditioned by the fixture design process.The third level describes those entities that present a complete dependence to the fixture design process. In this level, cannot be reused the knowledge previously defined (structures, relationships and attributes), d

50、ue to dependence of the process developed.4.2. Synthetic task definitionThe definition of the synthetic tasks involves the identification of those objects linked with the inference procedure carried out in the fixture design process. In this type of tasks, it cannot have a total reutilization of the

51、 knowledge, because the inference process carried out using a group of production rules that depend of the type of process executed.Under this classification, the knowledge group of functional design establish the functional solution of the fixture definition: the supporting surfaces,locating and cl

52、amping of the part. The definition of these surfaces is depending to the manufacturing process developed. This last characteristic makes thatthe functional design possesses depend of the machining processes developedduring the manufacturing of the part. In this sense, the sharing knowledge ofthis gr

53、oup is limited to the definition of the surfaces and supporting points,locating, clamping for machining fixture and to selection of the functional elements. However, the knowledge group of functional elements can be reusedFig. 5. Knowledge template for functional elements entity.in other applications, due to the functional elements can be employed in multiple do