Embroidery and sewing machines can utilize rotary hooks to attach thread to materials. An adhesive joint configured to sever if the rotary hook becomes jammed prevents damage to the rest of the drive system. The severable joint is located between a sleeve and a drive shaft nearest the rotary hook to allow for easy removal and repair of the joint.

Disclosed herein are a lower-thread supply device of sewing machine and a sewing method. The device includes a bobbin case (300) having an outlet (330) from which lower thread is drawn out, and a needle through-hole (340) through which a needle (600) moving downwards with upper thread (a) being fitted passes, and a hook body (200) in which the bobbin case (300) is mounted, the hook body being installed to be rotatable by a power device of a sewing machine, guiding upper thread (a2) on a sewn fabric side to a front area of the bobbin case (300) while catching and dragging the upper thread (a) via a hook (210), and guiding upper thread (a1) on a spool side to a rear area of the bobbin case (300). The bobbin case (300) is installed not to be rotated when the hook body (200) rotates.

Hook (11, 12, 13, 14) for a lockstitch sewing machine, or parts of the hook such as the support element of the tension spring (in particular the basket or the bobbin case) or the tension spring itself, including a tension spring (80, 90, 100, 110, 120) that includes a bending towards the outside (with respect to the support element on which it is mounted and with respect to the main bending radius of the tension spring) of the tension spring's extremity designed to press on the bobbin thread, so that the pressure point (P) on the bobbin thread is the point of tangency between the bending radius (R) of the bending of the tension spring's extremity and the support element of the tension spring, so as to generate a stable tension of the bobbin thread.

Hook (11, 12, 13, 14) for a lockstitch sewing machine, or parts of the hook such as the support element of the tension spring (in particular the basket or the bobbin case) or the tension spring itself, including a tension spring (80, 90, 100, 110, 120) that includes a bending towards the outside (with respect to the support element on which it is mounted and with respect to the main bending radius of the tension spring) of the tension spring's extremity designed to press on the bobbin thread, so that the pressure point (P) on the bobbin thread is the point of tangency between the bending radius (R) of the bending of the tension spring's extremity and the support element of the tension spring, so as to generate a stable tension of the bobbin thread.

The present invention relates to a vertical full-rotation shuttle, which leads a feed-side string portion of a needle thread loop to be wound around and hooked to a bobbin thread from one side of a bobbin case to the other side thereof according to the rotation of a hook part, and leads a stitch-side string portion of a needle thread to the surface of the bobbin case at one side of the bobbin case, such that the feed-side string portion of the needle thread turns the bobbin thread around and the needle thread loop jumps over the bobbin case so as to form complete stitches

The present invention relates to a vertical full-rotation shuttle, which leads a feed-side string portion of a needle thread loop to be wound around and hooked to a bobbin thread from one side of a bobbin case to the other side thereof according to the rotation of a hook part, and leads a stitch-side string portion of a needle thread to the surface of the bobbin case at one side of the bobbin case, such that the feed-side string portion of the needle thread turns the bobbin thread around and the needle thread loop jumps over the bobbin case so as to form complete stitches

A thread feeding system for any machine that requires a locking stitch is provided. The lower thread of the lock stitch is delivered from the inside of a rotary hook system or oscillating system of a lock stitch sewing machine. The rotary hook or oscillating hook is held in place by a bearing which is then attached to the chassis of the sewing machine. The rotary hook or oscillating hook is allowed to be driven by teeth on the inner bearing, and they may be located inside or outside, fore or aft to the positioning of the outer bearing. This allows for the void now left inside the rotary hook or oscillating hook where a pipe or tube is placed to feed the lower locking stitch thread.

Provided is a horizontal rotary hook including: an inner rotary hook including an attracted member made of metal in an outer lower surface portion; a permanent magnet that attracts the inner rotary hook; a magnet plate accommodating the permanent magnet and provided with a mounting hole at a center of a diameter thereof; a non-metallic outer rotary hook accommodating the magnet plate and having a shaft hole at a center of a diameter of an inner bottom portion thereof; and a hook supporting shaft that is inserted through the hole of the magnet plate and the shaft hole of the outer rotary hook and includes, at an upper end thereof, a flange for rotatably supporting the outer rotary hook and the magnet plate. A friction coefficient of a contact surface of the magnet plate that comes into contact with the outer rotary hook is set to be larger than a friction coefficient of the flange of the hook supporting shaft.

The present invention relates to an under-thread supply device for a sewing machine, and more particularly, to an enhanced under-thread supply device for a sewing machine, in which the device of the present invention and a unit for mounting said device are just partially changed so as to increase the winding amount of the under-thread of conventional sewing machines in order to achieve improved efficiency of sewing and efficiently reduce the puckering of a work piece without causing changes in the basic structure of conventional sewing machines.

The present invention relates to an under-thread supply device for a sewing machine, and more particularly, to an enhanced under-thread supply device for a sewing machine, in which the device of the present invention and a unit for mounting said device are just partially changed so as to increase the winding amount of the under-thread of conventional sewing machines in order to achieve improved efficiency of sewing and efficiently reduce the puckering of a work piece without causing changes in the basic structure of conventional sewing machines.