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 design guidelines and design specifications based on the design procedures. There are seven steps to construct the proposed system, which will be described in the following sections.

4.1 Die structure analysis

Progressive dies contain piercing, blanking, drawing, restriking, bending, and side-punching and cutting processes and have very complicated structures. It is necessary to plan a complete and systematic layout for the overall structure of the progressive dies. Therefore, for the proposed system, not only the construc-tional logic of die design operation could be developed, but also any possible mistakes in the die design could be prevented.

To layout the die structure, we first collect the structures of all kinds of progressive dies. Then, each progressive die is pided into blanking, drawing, piercing, bending, and cam dies according to its stamping process. After that, the main parts of the aforementioned dies are identified. Finally, we perform analyses on the design and functions of the main parts of the dies. At the same time, the parameterized die design system takes the changeable sizes of a die structure as param-eters and then changes the die structure sizes by assigning appropriate values to each of the parameters based on the design formulas, constraints, and tables derived from the design information, guidelines, and specifications. However,

 certain functional modulus, such as the punch lock, guide mechanism, guide post lock, fix, lock, type of plate, and blank fix, cannot be designed simply by changing the design param-eters because of the persity of their structures. Therefore, various structures of the main parts for a progressive die are partitioned into functional features, and the same functions are categorized into a single identical functional module. Figure 8 shows a classification of the features for the main parts of a typical progressive die based on their functionality.

4.2 Design process standardization

The object of design process standardization is to provide a systematic procedure of designing dies. Because the CAD system has its own modeling process, the size, position, and direction of functional features cannot be determined until the size, position, and direction of certain functional features are fixed. A standardized design process of the main parts, as shown in Fig. 9, is generated based on the design guide-lines and specifications for each of the functional features of the main parts as well as the cause-and-effect relationships among these functional features. This standardized process is used to guide the design of the main parts for the skeleton mechanisms of progressive dies, such as their structures and initial sizes as well as the initial sizes, positions, and di-rections of each functional feature on a main part.

 Fig. 9 A stardardized deisng process for skeleton mechanism of progressive dies

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4.3 Parameter settings

After the design process is standardized, to perform para-metric modeling of the progressive die in the CATIA system to conform to the design information, it is necessary to assign a parameter name to a changeable dimension. Therefore, it can define the formula of a parameter based on its relationship with the design conditions. Moreover, there are hundreds of parameters in our automatic design system, which demand a systematic and appropriate naming schema so the parameters can be well managed to facilitate coding and debugging.

The name of a parameter used in our system consists of two parts: the name of the part to which the parameter belongs and the name of the dimension. Based on the parameters’ functionality, they can be pided into shape parameters and position parameters. Shape parameters can be further classified as global parameters and local param-eters. Local parameters only need to meet the design