1、A functional approach for the formalization of the fixture designprocessR.Huntera, J.Riosb, J.M.Pereza, A.VizanaA Department of Mechanical and Manufacturing Engineering, Escuela Tecnica Superior de Ingenieros Industriales, Universidad Politecnica de Madrid, Jose Gutierrez Abascal, 2, 28006 Madrid, S
2、pain B Currently in Enterprise Integration (Bldg 53), Cranfield University, Cranfield, MK43 0AL, UK Received 14 January 2005; Accepted 14 April 2005. Available online 26 August 2005.AbstractThe design of machining fixtures is a highly complex process that relies on designer experience and his/her im
3、plicit knowledge to achieve a good design. In order to facilitate its automation by the development of a knowledge-based application, the explicit definition of the fixture design process and the knowledge involved is a prior and a fundamental task to undertake. Additionally, a fundamental and well-
4、known engineering principle should be considered: the functional requirements and their associated constraints should be the first input to any design process. Considering these two main ideas, this paper presents the development undertaken to facilitate the automation of the fixture design process
5、based on a functional approach.In this context, the MOKA methodology has been used to elicit fixtures knowledge. IDEF0 and UML have been used to represent the fixture design process. A methodology based on the function concept and aiming to formalize such design process is proposed. Fixture function
6、al requirements have been defined and formalized. Functional fixtures elements have been used to create a functional design solution, the link of these elements with the functional requirements and with typical commercial fixture components has been defined via tables and rules mapping. And finally,
7、 a prototype knowledge-based application has been developed in order to make an initial validation of the proposed methodology.Keywords: Fixture design process; Fixture knowledge modeling; Fixture functional requirementsArticle Outline1. Introduction2. Analysis of machining fixtures requirements2.1.
8、 Functional requirements3. Proposed methodology for the formalization of the fixtures design process4. Fixture functional design process model5. Information model, instantiation, and methodology validation6. ConclusionsReferences1. IntroductionThe main objective of any design theory is to provide a
9、suitable framework and methodology for the definition of a sequence of activities that conform the design process of a product or system 1. In general, all of them identify requirements as the starting point in the design process. In fact, the engineering discipline dealing with product design can b
10、e defined as the one that considers scientific and engineering knowledge to create product definitions and design solutions based on ideas and concepts derived from requirements and constraints 2, 3 and 4.For this research, a relevant issue when considering requirements, taking this as a general con
11、cept, is to make explicit the meaning of two main terms: Functional Requirement (FR) and Constraint (C). A functional requirement, as it stated by different authors, represents what the product has to or must do independently of any possible solution, 2 and 4. A FR is a kind of requirement, and cons
12、idering some basic principles widely recognized in the field of Requirements Engineering, we could add it ISA unique and unambiguous statement in natural language of a single functionality, written in a way that it can be ranked, traced, measured, verified, and validated. A constraint can be defined
13、 as a restriction that in general affects some kind of requirement, and it limits the range of possible solutions while satisfying the requirements. So, a constraint should be always linked to a requirement, and its purpose is to narrow the design outcome to acceptable solutions.Considering the Theo
14、ry of Axiomatic Design 4, functional requirements should be defined in the functional domain, which brings on the scene the issue of how to define and represent the functionality of a product. The way used to represent it will affect the reasoning process of the designer, and in that sense, the mapp
15、ing between the functional and the physical domains, being the later the one where the design solutions are developed. Several authors have investigated the concept of functionality and functional representation 2, 5 , 6, 7 and 8. Their design approach provides a view based on the Function-Behavior-
16、Structure framework, where function is defined using structure and behavior 6. The objective is to fill the gap that allows a designer to progress from Frs. to physical design solutions. The approach is that product functions are achieved by means of its structure, which seems to lead to an iterative causal approach, where solutions are sought until the selected structure causes the intended functi
