METHOD AND DEVICE FOR SEPARATING THE NEEDLE AND THE LOOPER THREADS ON DOUBLE-THREAD LOCKSTITCH SEWING MACHINES HAVING A LOOPER REVOLVING ABOUT A HORIZONTAL PLANE

摘要

The invention relates to a method and a device for separating the needle and looper threads on double-thread lockstitch sewing machines having a looper revolving about a horizontal plane, wherein after completing the seam the stitched product is moved further along by means of the feeder device by an amount that is shorter than the stitch length forming the seam, whereby in this position of the stitched product at least one further stitch (knotting stitch) is formed with the feeder device inactive, and in the unchanged position of the stitched product the needle thread loop is expanded by the looper during the formation of a partial stitch (cutting stitch), wherein the catch-thread device (14) is moved from an idle position positioned laterally behind the needle (5) to a movement reversing position along a movement path extending between the piercing hole (13) and the lateral walls (16) of the looper (1), and the catch-thread point (17) penetrates into the expanded needle thread loop such that both the arm of the needle thread loop for guiding the stitched product and the region of the looper thread extending from the looper to the stitched product are laterally deflected, and in the movement reversal position of the catch-thread device (14) are both grasped by a barbed hook (18) disposed thereon and guided to the region of the piercing hole (13).