A generic framework for design evolution: From function-to-form mapping to synthesis of tolerances
A generic framework for design evolution: From function-to-form mapping to synthesis of tolerances
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发表时间：
2003
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通讯作者：
N. Pramanik
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作者：
N. Pramanik
新产品（工件）的设计从一组用户规范开始，这些用户规范是工件必须满足的功能需求（FR）。最初，FR 集几乎总是不完整的，因为在概念设计阶段并不知道有关产品的完整知识。在这项工作中，提出了两种互补的方案：用于概念设计的设计综合方案和用于制造零件的公差综合方案。在第一阶段，提出了功能到形式的映射过程，以获得满足 FR 的概念设计。该过程在设计演进的各个阶段中进行，并且在每个阶段，使用 FR 作为约束并使用工件内部参数的变化作为映射过程的导航器来转换产品规范 (PS)。在第二阶段中，在计算出工件零件的标称尺寸（使用特定于领域的设计规则）之后开始，提出了一种合成制造零件公差的方法，作为优化过程，以在可装配性和功能要求的约束下最小化制造成本。使用基于偏差的通用公式来表示特征的变化，并且使用面向对象的表示在 UML 中对公差综合过程中的实体进行了建模。引入了一种新的基于偏差的制造成本模型。优化方案用于查找一组最佳偏差参数，然后使用偏差-公差映射系统根据 ASME Y14.5M (1994) 公差方案将其转换为标准公差规格。公差综合方案的实现可作为可与标准 CAD 软件包链接的工具，为设计人员提供产品开发和公差综合迭代解决方案的机制。
Design of a new product (artifact) begins with a set of user specifications which are functional requirements (FRs) that the artifact must satisfy. Initially, the set of FRs is almost always incomplete because complete knowledge about the product is not known at the conceptual design stage. In this work, two complementary schemes are presented: a design synthesis scheme for conceptual design and a tolerance synthesis scheme for manufactured parts. In the first phase, a function-to-form mapping process is presented to arrive at a conceptual design that satisfies the FRs. This process is carried out in stages of design evolution and at each stage the product specification (PS) is transformed using FRs as constraints and variation of internal parameters of artifacts as navigator for the mapping process. In the second phase, which starts after the nominal dimensions of the parts of an artifact have been computed (using domain-specific design rules), a method for synthesis of tolerances for manufactured parts is presented as an optimization process for minimizing manufacturing cost subject to constraints of assemblability and functional requirements. A generic deviation-based formulation has been used to represent the variations of features and the entities in the tolerance synthesis process have been modeled in UML using object-oriented representation. A new deviation-based model for manufacturing cost has been introduced. The optimization scheme is used to find a set of optimal deviation parameters, which are then transformed into standard tolerance specifications as per ASME Y14.5M (1994) tolerancing schemes using a deviation-totolerance mapping system. The tolerance synthesis scheme is implemented to serve as a tool that could be linked with standard CAD packages to give the designer a mechanism for iterative solution for product development and tolerance synthesis.