Buttonhole sewing machine

摘要

Buttonhole sewing machine has a reversing unit in the later cutting mode. A needle speed unit for the zigzag stitching is operated by a fourth motor (50). To form the required intermediate material in the buttonhole loop, the swing movement of the needle shaft (4) is affected by the fourth motor (50). The fourth motor (50) is a step motor. A data input takes the various parameters for the buttonhole to be passed to the sewing machine control. At least one memory allows calculation of the stitch co-ordinates from the parameters, to give the buttonhole loop, where the initial and later cutting modes are stored. The stitch width is constant in the initial and later cutting modes. The needle swing unit has an oscillating shaft (154) with a tooth segment, which meshes with a drive pinion at the fourth motor (50). The tooth segment has a connecting lever (54) with the oscillating shaft (154). Limit stops define the swing movements of the tooth segment, formed at a limit plate. The control sets the operation of all four motors (13, 18, 50) according to the computed stitch co-ordinates. The table (9) is moved by step motors. The rotary drive for the needle shaft (4), needle (6) and looper (11) is a step motor (13).