Method and sewing machine for approaching a predetermined end point of a seam

US4587915A · kind A · utility

Assignee

• PFAFF INDUSTRIES MASCHINEN AG · DE

Inventors

• Herbert Wenz · Kaiserslautern, DE
• Franz Schneider · Göppingen, DE

Key dates

• Filing date: Nov 20, 1984
• Grant date: May 13, 1986
• Expiry date: Nov 20, 2004

Classification

• Technology area (CPC D): Textiles; Paper
• CPC primary: D05B27/22
• WIPO field: Textile and paper machines
• WIPO sector: Mechanical engineering

Abstract

A method for approaching a predeterminable end point of a seam spaced from the edge of a workpiece, with a sewing machine which comprises an adjustable needle and lower transport, a sensor arranged before the needle and triggering the process for the positioning of the needle in the end point during passage through the edge, a pulse generator coupled with the main shaft of the sewing machine for the delivery of counting pulses for a pulse counter, and a micro-computer which controls the action of the feed means as a function of the pulses originating from the sensor and from the pulse generator. To execute a desired shortening of the length of one or more of the last stitches before the end point of a seam, the workpiece is moved back by the difference between the desired stitch length and the stitch length set by the setting device, before execution of the adjusted feed. For correction of the stitch length executed during the feed phase, the cloth feeder is connected with a switching gear controlled by the micro-computer for controlled switching on during its reversed feed phase which precedes the respective forward feed phase.