Mercedes-benz Aktiengesellschaft

Dieter Stegemann

Volker Thoms

Wilfried Reimche

Mathias Liewald

Stephanus Faller

The invention relates to a method for the iterative process optimization of drawing processes, occurring in timed sequence, in drawing presses. The clamping force which can be set at the blank holder is reduced in the case of fractures or increased in the case of part folding or maintained at the same level in the case of acceptable parts. In order to be able to detect the drawn part quality with respect to the criteria of 'fractures', 'acceptable' or 'folding' automatically during each working cycle the normal variation of the drawing sound is determined by means of a sound emission analysis of the structure-borne sound caused by the drawn part during the drawing process in the drawing tool, and from this a characteristic level course from periodic to stochastic sound components is determined. During the production of the drawn parts, the structure-borne sound signal is examined in each case with regard to the simultaneous occurrence of abnormal amplitude discontinuities in a wide frequency spectrum and, if appropriate, it is concluded that there are 'fractures'. Furthermore, the structure-borne sound signal is examined in each case with regard to the temporal level course from periodic to stochastic sound components and, if appropriate, it is concluded that there are 'folds'.

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Munich, Georgia

Dieter Stegemann