The tandard parts are assembled among various main parts according to the hole identification module, as shown in Fig. 13. In the module, there are five identification rules, and each identification rule corresponds to one standard part. After one standard part is chosen based on its shape,

 diameter, and length, the chosen standard part is assembled into the hole of the main parts.

4.7 User interface

The user interface allows a user to design progressive dies with the proposed system in a user-friendly environment. The user interface is constructed using the VB module contained in CATIA V5.

The user interface in our system is tabbed and classified into two categories, as shown in Fig. 14. The first category is used to input/output graphic information, such as input-ting strip layout, blanking lines, die face, punch open line, piercing lines, bending lines, side-piercing lines, and cutting lines by typing the path of import files and outputting the designed progressive dies with related 3D drawing by typ-ing the path of stored files. The second category is used to

 5 Case study

The developed system is explained with the automated struc-tural design of progressive dies for the upper shell of a mobile phone, as shown in Fig. 15. First, the sheet metal strip layout is drawn and then its functional surface and lines, such as die face, blanking line, punch open line, piercing line, bending lines, side-punching line, cutting lines, are assigned. After the

automated structural design system is started, users begin to input the strip layout with functional surface and lines, sheet thickness, and progressive pitch. After the RUN button is pressed, our system begins to generate the main parts of the progressive die based on the design processes, guidelines, and specifications. After that, the assembly design is executed. The holes of the main parts are identified and the appropriate standard parts are chosen from the standard parts database and assembled into the holes of the main parts. After every hole of the main parts is assembled into a standard part, the design of the progressive die is finished. Also, the engineering drawing of main and standard parts are generated automatically.

The progressive die for the upper shell of mobile phone includes 79 and 180 pieces of main and standard parts, respectively. The automated structural design system takes less than 2 h, while it would take the traditional 3D CAD system more than seven working days to complete the same work.

6 Conclusions and future works

This paper illustrates an automated structural design system for progressive dies with drawing, bending, and cutting oper-ations which is built on top of the CATIA V5 software. Upon receiving the initial design information from design engineers, such as strip layout, blanking line, die face, punch open line, piercing line, bending lines, side-punching line, cutting lines, sheet thickness, and progressive pitch, the system can auto-matically generate the final design of the main and standard

 Int J Adv Manuf Technol (2013) 68:1887–1899 1899

 parts of the die. The main parts cover the upper die set, lower die set, die plate, punch plate, blank pressure plate, punch back plate, upper lifting, lower lifting, cam mechanism, blanking punch, bending punch, and dies; the standard parts cover the socket head cap screws, dowel pins, stripper blots, guide posts, and plain guide bushings. The design formulas, identification rule, and geometric operations of the modeling processes are generated by the system using the built-in mod-ules of CATIA V5, such as Part Design, Assembly Design, and Knowledge Advisor. The proposed system can success-fully automate the structural design of the main and standard parts of the progressive die of an upper shell for a mobile phone within 2 h, whereas a 3D CAD system would take about seven working days to accomplish the same work. Thus, it can dramatically save on time and costs for designing the main and standard parts of progressive dies and also provide excellent design quality.