SEWING-OVERSTITCHING MACHINE WITH THREAD TIGHTENING AND RELEASING DEVICES Russian patent published in 1999 - IPC

FIELD: sewing industry. SUBSTANCE: sewing-overstitching machine has casing, needle carrier, adjustable thread tightening device with immovable tension washers and movable tension washers which are pressed to immovable washers by variable-rigidity springs, regulators for changing spring force, and thread releasing device. Control lever of thread releasing device is formed as cover rotating in vertical plane and mounted in front of needle carrier. Cover is disposed in lower position during sewing process and in upper position in the process of charging thread into machine. Controlled thread tightening and releasing devices are positioned on cover. Immovable and movable washers of thread tightening device are aligned relative to cover axis of rotation. Variable-rigidity V-shaped springs for tightening movable washers are arranged along cover so that their one ends cooperate with slide-type regulators and other working ends cooperate with movable washers. V-shaped springs have mid portions provided with axially aligned openings extending in parallel with axis of rotation of cover. Thread releasing device ejector positioned in openings is spring-biased in the direction opposite to direction of action of working ends of V-shaped springs. When cover is in lower position, ejector free end comes into engagement with casing to be moved into cover. As a result, gap is defined between stops spaced along ejector body and working ends of V-shaped springs, which load movable washers with tightening force. When cover is in upper position, ejector is forced by related spring to opposite side to define gap between working ends of V-shaped springs and thread tightening movable washers, thus releasing threads to facilitate passage of threads along thread guiding channels of machine. EFFECT: simplified construction and increased safety of sewing machine. 4 dwg