Importance

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Abstract

A sewing machine has a table, driven in one plane and carrying the material to be sewn, a stitch-forming device and a cutting device for producing a buttonhole in the material to be sewn. The buttonhole is provided with an incision, is produced in the pre-cutting or post-cutting mode and is bounded by zigzag stitches, running around the incision, of a buttonhole bead. The sewing machine has sewing tools comprising a needle bar, which is driven up and down and oscillates in the horizontal direction, and a needle, which is provided at the bottom end of the needle bar and interacts with a looper mounted in a base plate. An adjusting device sets the position of the zigzag stitches being provided in order to provide intermediate material (b) within the buttonhole bead in the post-cutting mode for allowing the material to be cut, without cutting the already-formed buttonhole bead. The oscillating motion of the needle bar is controllable by a selective drive mechanism, the position of the zigzag stitches being changed in direct coupling with the rotary position of the sewing tools by shifting the drive mechanism.

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First Claim