Industrial competitiveness in modern society depends on the ability to adapt a so-called job-shop production system to ever-changing demanding consumers. This results in more emphasis being laid on more efficient trial manufacturing techniques, the main targets of which lie in reducing the development period at low cost. In the field of trial manufacturing using sheet metal, especially automobile industry, almost parts of the process have depended greatly on the skilled workers, from which great reduction of the development period cannot be expected. A new forming technique is required.
In this work, a new computerized incremental forming method having high flexibility has been developed. In the method, the ordinary tools are replaced by various small tools, and only the small local region of a sheet blank is incrementally deformed by movement of these tools. Since a small tool moves over the arbitrary surface of the dies using a NC machine, it is possible to produce three-dimensional and non-symmetric parts directly from the CAD data. Arbitrarily shaped dies are made by LOM(Laminated Object Manufacturing), which is one of the Rapid Prototyping Methods. A forming machine is designed and developed by introducing a computer to control the movement of the tools. Using the method, a sheet blank is stretched with drastically improved formability as compared with conventional stretch forming, and the surface is desirably good by ironing effect. In order to increase formability and product quality, the step-wise forming method has been proposed. For the step-wise intermediate geometry, a surface blending method and selective pre-conditioned area method have been used. The method makes the maximum strain value decreased and the strain distribution be uniform, since the deformation pass is controlled. With increasing number of passes, more improved deformation is obtained.
