A compact and practical CAD system for blanking or piercing of irregular-shaped sheet metal products and stator and rotor parts

This paper describes the development of a computer-aided design of blanking and piercing for irregular-shaped sheet metal products and stator and rotor parts. An approach to the compact and practical CAD system is based on the knowledge-based rules. Knowledge for the CAD system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. The system has been written in AutoLISP on the AutoCAD with a personal computer and is composed of six main modules, which are input and shape treatment, production feasibility check, blank layout, strip layout, die layout, and drawing edit module. Based on knowledge-based rules, the system, STRTDES, is designed by considering several factors, such as complexities of blank geometry and punch profile, availability of press equipment and standard parts, utilization ratio which minimizes the scrap in a single or a pairwise operation, bridge width, grain orientation and design requirements which maximize the strength of the part when subsequent bending is involved. Therefore, this system can carry out a die design for each process which is obtained from the results of an automated blank layout drawing with the best utilization ratio for the irregular shape of the product, which was successful in the production feasibility check module, and those of an automated strip layout drawing. It can then generate part drawings and the assembly drawing of the die set in graphic form. The developed system provides its efficiency and effectiveness for blank layout, strip layout, and die layout of irregular-shaped sheet metal products and stator and rotor parts.