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It is a well known industry fact, that the geometry of material in contact with tooling, is a major factor which affects its formability. A collary to this is that many problems can be identified and solved using geometry based mechanics approaches. Because of the simplicity in modelling, and hence speed of processing, the geometric based tooling contact techniques are gaining more and more acceptance as tools for product, process and tooling design of automotive stampings. The paper describes the implementation of a stretch/draw formulation of tooling contact, in two dimensions. The formulation is based on a belt friction assumption, with special elements developed to deal with thickness distribution around the contact area. The program tracks the change in the location of the neutral point at every forming step. The program is designed to handle multi-tooling as well as multi-stage forming operations.

The paper introduces the concept of process signatures, the main intention being to change the grid analysis from a merely data processing activity to a knowledge based methodology. The process signature is the shape of the strain envelope, which depicts the strain state of contiguous elements on the surface of a stamping. The signature is strongly influenced by the tooling geometry, process induced modes of deformation, and to a lesser extent by the lubricating conditions, material characteristics, etc. Essentially the deformation of the whole part can be analysed by subdividing it into the fundamental modes. It is shown that the total response of a stamping depends on certain combination of these basic fundamental signatures. Distinct areas on the signature correspond to the punch and die actions. The work demonstrates that the process signatures respond in a predictable fashion to changes in tooling, material and set up.

Blank development is the basis for calculating the material cost and hence the product cost, at the quoting stage. Understanding the metal flow under the binder is a critical activity during the tooling design stages, as well as during phototyping. The paper describes a computer aided blank development and metal flow analysis system, that will assist in performing the functions described above, before the tools are built, for box shaped parts drawn in multi-stage forming operations with a flat punch face, and a flat binder. Development of the minimum blank shape, using the SLF technique for shrink flanged components is not new. The paper addresses the extension of the approach to: i. multi-stage forming operations and, ii. the incorporation of the effect of thickness changes on the blank shape. Applications are given in the paper using the computer program BLANKDEV.