Abstract
板金件的設計者需要一種方法能有快速且有效的設計出可加工的板金件。亦即能適時的建構出板金件的設計圖形，且此一設計能產生出一個合理且易於製造的製造程序規劃。在本論文中，提出了一個以製程特徵為基的板金件特徵表達架構(feature representation scheme)，藉由此特徵表達架構，設計者能利用特徵來描述或定義所要的板金件設計。這些特徵被區分為兩種主要的類別，一種稱之為主特徵(master feature)，主要是用來表達板金件的外形元素。另外一種則稱為製造特徵元素(manufacturingfeature entity)，是用來代表在板金件上依功能需求而必須執行之製造程序。而製造特徵元素所需的形狀則由一些基本的形狀特徵來定義。使用者亦能藉由這些基本的形狀特徵來定義複合特徵，以滿足某些產業特定的需求。另外，為了使設計更能直接應用於製程規劃、產品組合與品質檢驗，幾何與尺寸公差資訊是非常重要的。因此，幾何公差與尺寸公差資訊亦能加入到特徵資訊之中；也就是說，特徵的資料結構不只是有幾何（尺寸）與拓撲資訊，同時亦包含有公差資訊。在本論文中，根據所提出的特徵表達架構，亦利用ACIS實体模型建立了稱為SMCAD的電腦輔助板金件設計系統。In sheet metal product and process design, there is a strongdemand to find a methodology that can produce sheet metalproduct design efficiently and effectively. An "efficient"design process means creating a design in the timely matter.On the other hand, an "effective" design process creates avalid design that can easily be manufactured. In this thesis,a process-driven feature-based methodology is developed tofulfill the demands. We propose a feature representationscheme for sheet metal parts. By using this featurerepresentation scheme, the designer can use the features todescribe or design the sheet metal part. The features can beclassified into two primary types. One is called masterfeature, which is used to represent the primary profile of thesheet metal part. The other type is called manufacturingfeature entity, which represents a single sheet metalmanufacturing process. Some primitive features are defined torepresent the manufacturing feature entities. Compoundfeatures can be defined by users to fulfill some specificdesign intention. In order to present a sheet metal partdesign that is readily for sheet metal processes, thesubsequent assembly and inspection, the tolerance informationis vital. Thus, the geometric and dimensional toleranceinformation is allowed to add into feature definition in thisthesis. The data structure for the feature-based design isdeveloped considering not only topology and geometry but alsotolerance data. A prototype system, called SMCAD, has beenimplemented in a solid modeler, called ACIS, based on thefeature representation scheme and data structure proposed inthis thesis.