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3.2 Program based on library feature

SolidWorks software provides a series of redevelopment application programming interface (API) functions. The programmer can use Visual Basic, Visual C++, or other programming tools that support the object linking and embedding technology to call these API functions directly. These functions can be used to deal with the library feature by accessing “LibraryFeatureData”. On the basis of hole library features, developer can get the parameters and configurations for each hole file with extension filename “.sldlfp” and use them to model the plate holes which are in accordance with the design standard and criteria. This method reduces the programming workload and is more convenient and efficient than holes modeling step by step by program. So the redevelopment cycle is shortened.

3.3 The structure of automatic correlated hole design system

In order to implement the hole design task according to the criteria and standards, the proposed system also allows the user to assign the type of functional features in order to replace the design with the existing functional features. The

architecture of the proposed system, as shown in Fig. 12, includes the following: progressive die design knowledge base, holes location selector, model generator, and user interface. Each section is described below.

3.3.1 Standard parts and functional assembles library Standard parts and typical functional assembles Library are essential part of CAD system. Parameterized die design takes changeable sizes of die structure as parameters and then changes the die structure sizes by means of a relationship formula for the parameters so as to fulfill the design objectives. Taking the hook screw as an example, there are 12 design parameters based on the design standards shown in Fig. 7. Three configurations are built corresponding to three groups of parameters for hook screw part shown in Fig. 8. There are 70 such standard parts and 15 typical functional assemblies in our system. 3.3.2 Holes feature library

Holes feature library is composed of all kinds of holes which can be parameterized and located. For example, the through hole with different size can be modeled as a hole library feature which has only one changeable parameter, hole diameter. The composed hole is complex, so we deal

with the model by using multiple configurations, e.g., the hook screw hole library feature has three configurations, as shown in Fig. 9. There are ten such hole library features in our system.

3.3.3 Progressive die design knowledge base

For the progressive die design to be constructed with 3D standardization, it is necessary to analyze the die structure and categorize both constructional subparts and functional features of the die. Thus, the designer can systematically classify the die structure and understand the geometric operations necessary for each functional feature during the modeling processes. These data are stored in the format of a 3D solid model template and excel files. Table 1 is the excel file content for the hook screw and hole in which the first column records the size of screw and the second column restores the hole library feature configuration, respectively. Table 2 is the excel file for pilot pin assemble and holes on six plates. They can be used for training new designers, inquiring about die information, as well as the compilation, modification, and debugging of programs.

3.3.4 Holes location selector

This selector provides the location data for the relating parts to be inserted into the die and the holes to be modeled. There are two types of selections: One is through the point sketch, while the other one is selected from strip layout. The point sketch is composed by a series of points that are used to locate the parts such as guide post and pushing, screws, pins, and stoppers. For the punch (dies), pilot pins, lifters, and so on which are located inside the strip layout area, the location can be determined by the selection of points or contour in the strip layout. 3.3.5 Correlating parts selector

This selector provides the data of type and size related to the correlating parts. Therefore, when the system is used to design correlated holes, this selector would select the type and sizes related to parts according to the design criteria. The progressive die hole design system is divided into seven main plates and ten correlating parts, as shown in Fig. 13.

3.3.6 Model generator

The model generator can perform 3D hole modeling process and inserting relevant parts. It can be used to construct the solid model of correlated holes on