Application of pyrotechnic gas generators in sheet metal forming technologies

High speed forming is a traditional and long known process for the forming, joining and plating of blanks. The advantages are in general the high forming velocity and the possibility to handle materials, which could not be treated by conventional processes The economic criteria for this technique are single piece or small lot production, pieces too large for available presses and the avoidance of a thermal treatment. An additional advantage of the process is the strain hardening of the work piece during the process. Scope of this work was the application of pyrotechnic gas generators in a hydro forming kind of process and to extend the technology for cutting processes. Experiments are described, which use gas generator materials as a driving force in a deep drawing and a cutting process. During the work a new gas generator formulation was developed, which showed a minimal slag formation and moderate combustion temperature. Interior ballistic behaviour and combustion temperature were characterized. Materials tested were steel, stainless steel and aluminium with different thicknesses. The results show, that gas generators are a suitable mean for deep drawing applications. The performance of the gas generator process is directly comparable to the hydro forming process, but the time for the drawing cycle is much faster with the new method. The application in cutting processes showed the ability to punch more than one hole of the same geometry simultaneously with flash free cutting edge.