GB1311755A - Contactless synchronising device for sewing machines - Google Patents

Abstract

1311755 Controlling sewing machines FRANKL & KIRCHNER FABRIK FUR ELEKTROMOTOREN UND ELEKTRISCHE APPARATE 7 May 1970 [17 May 1969] 22084/ 70 Heading D1G For controlling stopping of and a needle thread cutter of a sewing machine a contactless synchronising device is provided comprising two rotating shutters, the first shutter 5 having a slot 22 which stops the machine in a low needle position and the second shutter 6 having a first slot 18 which causes a thread cutter to be brought under the stitch plate and a second displaced slot 19 which causes stopping of the machine in an upper position and withdrawal of the cutter to cut the needle thread. The shutter discs 5 and 6 are adjustably mounted on a shaft 2 which is driven from the machine shaft. The signals produced by the slots or other means at the receiver 17 of an optical, electrical or electronic indicating instrument control a multi-stage relay arrangement controlling the thread cutter magnets MI 1 and MI 2 , and a clutch and brake in the machine drive. On actuation of a switch key (T) the brake is applied and released by time-delay relays and the clutch then operated to rotate the machine slowly. When the slot 18 indicates the high needle position the magnet MI 1 is energised moving the cutter blade under the stitch plate and when the slot 19 actuates the receiver 17 the brake is re-applied, the magnet MI 2 is energised to withdraw the cutter blade to cut the needle thread and after a further time delay the brake is released to permit manual adjustment of the needle position. The magnets MII and MIII respectively release the needle thread tension during the cutting operation and draw the cut thread to one side of the presser foot so that it is drawn to the underside of a fabric.