3。2 Representation of the Design Rules

When designing a panel with prismatic shapes and complicated structure, the result- ing design tends to be different from the original design or even faulty even if the same design conditions and design processes are applied。 However, no one can clear out the reason due to the inherent complexity of design rules and structure。 [6-7] Therefore, it is important to establish robust design system which can give us consis- tent results especially when designing and manufacturing complex products。

To establish robust design system it is necessary to standardize the design process by extracting the design methods and rules through the careful analysis of design processes and variety of special features included in the design process。 [8]

In developing the press die design system, the design processes and the design rules are standardized by gathering information and know-how from the specialists and then storing them in a database to retrieve the information whenever necessary。 [4] The design rules are implemented in three groups:

1) Historic Rule: general design knowledge, features of design method for each component, selection of die type, selection of material for each component according to the shapes, maximum (or minimum) size of each component, location of each block, bolt location and the number of jig parts in each component, positioning di- mension,  the number and designing position of reinforcing rigs, etc。

2) Heuristic Rule: includes design method and know-how of the design specialists, location of each component in trim line and draw die shape, position decision factor, prohibition section of component separation, machining margin, method of pierce separating, width margin of scrap cutter, location of block, etc。

3) Procedure Rule: calculation of dimension according to the design formulation, design rule, mutual relation between the component’s height and width, separation length between each component, calculation of height between each component, etc。

The proposed design system has many advantages: The designer dependency can be reduced by saving the special know-how and experiences related to the design。 The new design of an object is corresponded quickly by storing the past design rules in the rule base。 [9] Also, modification and maintenance can be done easily。

3。3 The Process of Design Shape in Trim Die Design

To design a block in the quadratic domain the position and dimension of the block are determined by the face surface of the product included in the block feature using the enumerating method implemented in the design rule base。

The dimension of a block is determined in the sequence of width, height, and length after the designer sets the check gap of height in the shape。

When the designer decides the trim line and the start point, the positions of the blocks and the block widths are determined first。 The positions and widths of the blocks can be calculated by piding the trim line into equal parts by the check intervals determined with several rules。 Then the block heights bounded by the maximum heights (obtained by the shape checking routine) are calculated  so  as  to  minimize  the  machining  vol- umes。 Finally, the length of the block is determined using the width and the height of each block considering the size tolerance and weight of each block。

The system stores shapes and parameters of the resulting design as a feature informa- tion in the database so that the system can extract those information in case of designing a trim die with similar shapes and parameters。 [10-11]

3。4 The Process of Design Shape in Draw Die Design