Sewing machine control for buttonhole stitches moves the fabric advance and the sewing head to stitch reinforcement stitches at the ends of the buttonhole opening before the lockstiches are sewn

摘要

Through the control of the fabric movement system at a sewing machine, which stitches buttonholes (70), reinforcement stitches (185,186) are sewn before the lockstitches (73,74) at the buttonhole cut. They are sewn at a zone (73a,74a) where at least one of the lockstitch groups (73,74) is to be sewn, so that the reinforcement stitches (185,186) and the lockstitches (73,74) intersect each other. The buttonhole stitching (70) is made in the fabric, after the reinforcement stitches (185,186) have been sewn. The lockstitches (73,74) are sewn over the reinforcement stitches (185,186). The reinforcement stitches (185,186) are sewn only where stop stitches are not made, at the zones (73a,74a) where the lockstitch groups (73,74) are to be sewn. Before the buttonhole stitching (70), the fabric advance and the sewing head are controlled to form a number of loops of underlay stitches where each loop has a number of lines of linear reinforcement stitches at the zones (71a,72a) where the zigzag stitches (71,72) will be made along the sides of the buttonhole. A number of lines of lateral stitches are made at the zones (73a,74a) where the end lockstitches (73,74) will be stitched, and with lateral stitches (187,188) across the zones for the zigzag stitch groups (71,72). The fabric advance and the sewing head are controlled to position the fabric workpiece for a cutter to cut the buttonhole opening through zigzag stitching, and execute the buttonhole stitching (70). An Independent claim is included for a buttonhole sewing machine with a control to set the actions of the fabric advance and the sewing head to give the reinforcement stitches (185,186) before the end lockstitches (73,74) are sewn. Preferred Features: The control has selected modes for the sewing of the underlay stitches, the reinforcement stitches (185,186), the end lockstitches (73,74), and the whole buttonhole stitching (70). A reinforcement parameter setting unit determines the structure of the reinforcement stitching, and the pattern selection of the buttonhole stitching (70) includes reinforcement parameters. The control sets the stitching action, with zigzag stitches up one side of the buttonhole opening, and down the other side, and sets the start and end of the buttonhole sewing operation.