The process of press stamping provides excellent stamping efficiency and is indispensable for reducing cost through mass-production. Although it is a simple process for stamping work using punches and dies, it involves acomplicated mechanism because it is accompanied by the destruction of materials and plastic deformation. For this reason, a theoretical analysis is difficult, and in many cases, the stamping conditions are determined through research centering on qualitative methods and experience of field engineers. In this study, therefore,we investigated the possibility of applying quality engineering in press stamping and optimizing stamping conditions. As a result, it was clarified that quality engineering could be applied and the punch material and the plate holding force had major effects on the S/N ratio, and we could determine the optimum stamping conditions. We could also improve the heights of burrs, a quality characteristic.
Press forming is used at many manufacturing sites as a means of producing large quantities of products having the same shape in a short time. Press drawing,which can create a seamless three-dimensional shape, has the advantage that procedures such as welding can be skipped and less material is wasted, but friction becomes a major problem in this process. As friction generates blemishes,cracks, and heat in the product, it is commonly believed that a lubricant must be used during the pressing process, but then the lubricating oil must be washed off before the press-formed products are shipped. To establish a lubricant-free pressing (dry pressing) technology, which would greatly contribute to improvements in two major problem areas, environment and cost, a fundamental study directed toward optimization of dry pressing conditions was carried out using quality engineering techniques. As a result, a method was developed in which distortion generated in a pressing machine is used to evaluate pressing stability, and a start was made on the optimization of the dry pressing conditions.