| 摘要 |
The aim of the invention is to provide a method for mechanically locking a double chain stitch seam. The chain stitch is produced by means of an industrial sewing machine comprising a sewing needle and a sewing thread as well as by a main gripper comprising a gripper thread. The sewing direction is reversed for locking purposes. The aim of the invention is also to guarantee that the chain stitch seam is sewn in a simple and very precise manner by means of the inventive method and even when the sewing speed is high. According to the inventive method and after the sewing direction has been reversed, the thread loop which is formed by the sewing needle underneath th e web of fabric is received by the main gripper in the stitching rhythm of the sewing needle. The thread loop is subsequently pushed on the main gripper against the working direction thereof by means of an auxiliary component tha t is driven in a synchronous manner by the sewing machine. The needle thread which forms the thread loop is then joined with the gripper head and held in this position underneath the sewing level at a distance from the needle and the main gripper in front of said needle and gripper and in the forward sewi ng direction by means of said auxiliary component. The joined thread area is moved in the forward sewingdirection and a thread triangle formed by the needle thread rope that forms the loop is stretched in the gripper thread ar ea that extends in parallel in relation to the main gripper and in the gripper thread area that leads to the joined area. The sewing needle stitches into said triangle. The thread triangle is subsequently held open by means of the auxiliary component until the next thread loop of the needle thread is forme d. The joined thread area is released by the auxiliary component approximately at the same time.
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