Seam puckering preventing shuttle device of sewing machine

摘要

A puckering preventing shuttle device of a sewing machine capable of providing high quality stitches without producing puckering by eliminating needle thread extraction resistance on the outer periphery of a rotating hook bobbin case holder to reduce the tension of a needle thread so as to keep a balance between the needle thread and a bobbin thread and also enabling the proper tightening of the threads even in an extra-soft fabric. The device comprises the rotating hook bobbin case holder ( 80 ) storing a bobbin case storing a bobbin around which the bobbin thread is wrapped and detachably fixed to a machine frame and locked to the machine frame by rotating hook bobbin case holder stopper ( 90 ) to stop its rotation and a rotating hook ( 70 ) in which the rotating hook bobbin case holder ( 80 ) is installed, having a sword tip ( 75 ), and rotated by a lower shaft. A needle thread inlet (EN 1 ) and a needle thread outlet (EX 1 ) are formed at circumferentially different positions between the rotating hook bobbin case holder stopper ( 90 ) and the rotating hook bobbin case holder ( 80 ) where the loop of the needle thread picked up by the sword tip ( 75 ) for each rotation of the rotatingly driven rotating hook ( 70 ) forms a clearance for guiding in and out the needle thread on the outer periphery of the rotating hook bobbin case holder ( 80 ) by eccentrically disposing the rotating center (O 1 ) of the rotating hook ( 70 ) relative to the rotating center of the lower shaft.