OVERCAST SEWING-MACHINE FOR FORMING A MULTITHREAD OVERCAST SEAM

申请公布号：: WO9000640(A1)
申请号：: WO1989EP00616
申请日期：: 1989.06.01
申请公布日期：: 1990.01.25
申请人：: PFAFF HAUSHALTMASCHINEN GMBH
发明人：: HOLL, HELMAR;MEIER, GUENTER
分类号：: D05B1/20;D05B57/02;D05B57/06;(IPC1-7):D05B57/02
主分类号：: D05B1/20
摘要：: The aim of the present invention is to adapt a traditional sewing machine so that minimal adjustments are required to sew several different types of stitches. Several solutions are suggested for alternatively sewing stitches 512 and 514, comprising two needle threads, i.e. one gripper underthread and one gripper overlock thread. In one of the embodiments of said invention, the carrier (19) of the overlock gripper can be set in a first operational position, where both needle threads are interlinked together with the gripper overlock thread, and moved to a second operational position, where only the needle thread adjacent to the seam of the object being sewn is interlinked together with the gripper overlock thread. In another embodiment of said invention, two thread eyes (29, 30) are provided in the overlock gripper, at a given distance from each other, and the gripper overlock thread is passed through one of the needle eyes to form one of the types of stitches, and through the other needle eye to form the other type of stitch. Stitch type 504, comprising three threads, can be formed by removing one of the needles. To form stitch type 502, comprising a needle thread and a gripper underthread, without a gripper overhead thread, an overhead gripper (41) on the gripper carrier, having a forked catching tip (44), can be moved between a rest position and an operational position, in which the catching tip of the overhead gripper forms an extension of the catching tip fork branch of the overhead gripper furthest from the needle, by which the gripper underthread is carried around the seam of the object being sewn and positioned in front of the needle for insertion. In order to improve the tensile strength of the stitching, additional stitching tools for forming a double chain stitch seam of stitch type 401, DIN 61400, US Federal Standard Catalogue No 751, are added to the stitching tools for forming the corresponding overhead seam.