Patent ID: 7111568
Filing Date: 2006-09-26
Classification: D05B

Abstract:
1. A cover stitch sewing machine in which a plurality of needle threads are supplied to a plurality of needle thread eyes of a plurality of needles from a needle thread spool by way of a plurality of needle thread tensioning devices and a needle thread take-up, a looper thread is supplied to a looper thread eye of the looper from a looper thread spool by way of a looper thread tensioning device and a looper thread take-up, and a cover stitch of a double chain stitch seam is formed in a sewing material on a needle plate due to the intertwining of the needle threads of the respective needles and the looper thread of the looper in response to a cooperative operation of the plurality of needles and the looper, wherein the needle thread take-up includes a needle thread pulling-up spring on which the needle threads which are drawn out from the needle thread tensioning devices are thread-hung together with the needle thread take-up by a thread hanging point and hence, the needle thread take-up completes the drawing-up of the needle threads by the thread hanging point after needle thread loops of the respective needles are seized by the looper, the sewing material is fed by one feed pitch when the plurality of needles are moved down and the needle thread take-up runs out the needle threads, the needle threads are pulled up by the elasticity by the thread hanging point of the needle thread pulling-up spring thus preventing the occurrence of a slack of the needle threads which extendedly exist below the needle thread eyes and, at the same time, the plurality of needles move into the inside of substantially triangular spaces formed by the needle thread loops and the looper threads before one feed pitch, the looper is shed from the needle thread loops, and the needle threads which are connected with the needle thread loops from which the looper is shed are drawn up by the thread hanging point of the needle thread take-up against the resiliency of the needle thread pulling-up spring.