Abstract: A method for preventing seam ravel of multi-thread chain stitches is provided. After normal sewing is terminated with a looper set in a forward movement state, a state in which a needle thread loop caught by the looper is subjected to position-holding at a position closer to a forward movement end of the looper than a descent position of a needle is maintained until the needle descends through the needle thread loop caught by the looper. Thereafter, the position-holding of the needle thread loop is released to permit a sewing action for at least one stitch, thereby allowing the needle thread loop to be self-looped with a needle thread held by the needle. This surely strongly prevents the seam ravel of multi-thread chain stitches formed by the single needle, irrespective of the dimension of tension applied to the needle thread and the looper thread.

Abstract: A needle plate base in a multi-thread chain stitch sewing machine with a seam ravel preventing apparatus is divided into a left needle plate base for attaching a needle plate thereto and supporting a swinging support shaft of a thread hanging hook; and a right needle plate base for fixedly supporting a stopper member and a thread handling air cylinder and a stopper air cylinder. The right needle plate base is fastened to a sewing machine bed. The left needle plate base is fastenably and unfastenably fastened to an upper surface of the bed via screw members. Adjustment of stitch performation, and maintenance, e.g., replacement of various kinds of components stored inside the bed, can extremely easily and simply be carried out without having much trouble and requiring labor and time, and therefore, the stitch performation and predetermined ravel preventing function can be constantly surely reproduced.

Abstract: A method for preventing seam ravel of multi-thread chain stitches is provided. After normal sewing is terminated with a looper set in a forward movement state, a state in which a needle thread loop caught by the looper is subjected to position-holding at a position closer to a forward movement end of the looper than a descent position of a needle is maintained until the needle descends through the needle thread loop caught by the looper. Thereafter, the position-holding of the needle thread loop is released to permit a sewing action for at least one stitch, thereby allowing the needle thread loop to be self-looped with a needle thread held by the needle. This surely strongly prevents the seam ravel of multi-thread chain stitches formed by the single needle, irrespective of the dimension of tension applied to the needle thread and the looper thread.

Abstract: A band feeding device feeds a selected one of a plurality of band-type materials (e.g. cloth tape, rubber) to a sewing machine for sewing to a ring-shaped garment such as, for example, the waist or crotch of a pair of trousers or briefs. One of a plurality of secondary rollers is moved to pinch its respective band between itself and a main roller. All other secondary rollers are moved away from the main roller, so that only the selected band is fed. This permits changing the type of band material being fed to the sewing machine without requiring the operator to remove and reinstall band materials each time. The number of elements in the overall device remains small, thus providing an inexpensive and compact device.