An Automated Progressive Process Planning and Die Design and Working System for Blanking or Piercing and Bending of a Sheet Metal Product

This paper describes the development of a computer-aided design and manufacturing system for irregular-shaped sheet metal products for blanking or piercing and bending operations. The approach is based on knowledge-based rules. Knowledge for the system is formulated from plasticity theories, experimental results and the empirical knowledge of field experts. This program for the system has been written in AutoLISP using AutoCAD and on SmartCAM using a personal computer and is composed of nine modules, which are input as shape treatment, flat pattern-layout, production feasibility check, blank-layout, strip-layout, die-layout, data-conversion, modelling, and post-processor modules. Based on knowledge-based rules, the system is designed by considering several factors, such as material and thickness of product, complexities of blank geometry and punch profile, diameter and material of a wire, and the availability of a press. This system is capable of unfolding formed sheet metal to give a flat pattern and automatically accounts for the adjustment of bending allowances to match tooling requirements by checking dimen-sions and generating NC data automatically according to the drawings of the die-layout module. Results obtained using the modules enable the designer and manufacturer of blanking or piercing and bending dies to be more efficient in this field.