Pfaff Industriemaschinen Gmbh

Joachim Rosch

Heribert Geisselmann

Richard Wagner

A method and apparatus for the pattern-correct sewing together of two pieces of cloth having the same pattern by a sewing machine with one cloth feed mechanism arranged over and one arranged under the cloth pieces, the feed quantity of which is variably by at least one positioning system relative to each other, uses a sensor arranged upstream of a stitch forming point for each cloth piece and a signal processing unit which processes signals from the sensors corresponding to the relative position of the cloth pieces and which influences the positioning system for the feed mechanism in accordance with the established relative position of the cloth pieces. For the pattern-correct sewing together of the two cloth pieces, the pattern structure of each cloth piece is continuously determined by the sensors by measuring values of a structure-or pattern-typical criterion. The found values are sent as signals to the signal processing unit, and the signals of both sensors, taken from the two cloth pieces within the same predetermined length before the stitch forming point, are stored independently of each other in the signal processing unit as signal sequences. From the signal sequences the signal processing unit determines the momentary offset between the two cloth parts by calculation of their degree of overlap and thereby controls the positioning system.

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Enkenbach-Alsenborn, Germany

Joachim Rosch