A multi-thread chain stitch sewing machine with a seam ravel preventing apparatus wherein the multi-thread chain stitch sewing machine comprises a needle having a drop position moving up and down while holding a needle thread;
- a looper which is movable forward and backward while holding a looper thread in a direction substantially orthogonal to a vertical movement path of the needle, and catches a needle thread loop formed below a needle plate by the needle during a forward movement;
- and a needle plate base having the needle plate attached thereto and being attached to an upper surface of a sewing machine bed, and wherein the multi-thread chain stitch sewing machine forms multi-thread chain stitch seams on a fabric by allowing the looper to catch the needle thread loop formed below the needle plate by the needle, and then by interlooping the needle thread with the looper thread held by the looper, the multi-thread chain stitch sewing machine with the seam ravel preventing apparatus comprising:
- a needle thread holding mechanism comprising (i) a thread hanging hook which is approachable and departable with respect to the looper, and swings around a vertically extending support shaft in a plane substantially parallel to the needle plate between a standby position away from the looper and a thread hooking position close to the looper, and (ii) a hook actuator for drivingly swinging the thread hanging hook to the standby position and the thread hooking position;
- a stopper mechanism comprising (iii) a stopper member disposed at a position farther away from the needle plate than the thread hanging hook of the needle thread holding mechanism, and permits temporary suspension and unsuspension of a swing of the thread hanging hook from the thread hooking position to the standby position so that the needle thread loop caught by the thread hanging hook at the thread hooking position is held at a hold position between the thread hooking position and the standby position, and (iv) a stopper actuator for performing the suspension and the unsuspension of the stopper member;
- a connecting member for interlockingly connecting the thread hanging hook of the needle thread holding mechanism and the stopper member of the stopper mechanism;
- and
- a control section for controlling the needle thread holding mechanism and the stopper mechanism in association with a vertical movement of the needle, forward and backward movements of the looper, and feed of the fabric, so that the looper is moved forward after a normal sewing is terminated, the thread hanging hook of the needle thread holding mechanism is brought near the looper, the needle thread loop caught at the thread hooking position is moved to the hold position, a resulting state is maintained until the needle descends through the needle thread loop caught by the looper, and thereafter, a sewing action for at least one stitch is performed, wherein
- the needle plate base is divided into two sections:
- a left needle plate base for attaching the needle plate thereto and supporting a swinging support shaft of the thread hanging hook;
- and a right needle plate base for fixedly supporting the stopper member and the hook actuator and the stopper actuator, and wherein
- the right needle plate base is fastened to the sewing machine bed, and the left needle plate base is fastenably and unfastenably fastened to an upper surface of the sewing machine bed via screw members.