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.

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.

In thread cutting mechanism portions of a lower thread winding device, two groove portions of an inner threading groove portion and an outer threading groove portion are formed on a holder. In the inner threading groove portion, one end portion is opened to one of an intersecting direction intersecting with a radial direction of the holder at an outer peripheral portion of the holder and another end portion is located at an inner side of a small-diameter bobbin in the radial direction. The outer threading groove portion is located at an outer side of the inner threading groove portion in the radial direction of the holder. In the outer threading groove portion, one end portion is communicated with the inner threading groove portion and located at the outer side of a large-diameter bobbin in the radial direction and another end portion is located at the inner side of the large-diameter bobbin in the radial direction.

In thread cutting mechanism portions of a lower thread winding device, two groove portions of an inner threading groove portion and an outer threading groove portion are formed on a holder. In the inner threading groove portion, one end portion is opened to one of an intersecting direction intersecting with a radial direction of the holder at an outer peripheral portion of the holder and another end portion is located at an inner side of a small-diameter bobbin in the radial direction. The outer threading groove portion is located at an outer side of the inner threading groove portion in the radial direction of the holder. In the outer threading groove portion, one end portion is communicated with the inner threading groove portion and located at the outer side of a large-diameter bobbin in the radial direction and another end portion is located at the inner side of the large-diameter bobbin in the radial direction.

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

The present invention relates to a lower thread bobbin for a sewing machine able to hold a thread, the bobbin comprising a crescent moon-shaped winding part on which a thread can be wound and a crescent moon-shaped securing part for covering the winding part on which the thread has been wound. The lower thread bobbin for a sewing machine has the advantage of being able to hold a greater amount of a lower thread than the very limited amount of a lower thread that is wound on general conventional bobbins, and so increasing the efficiency of sewing work as the user or sewing machinist does not replace the bobbin frequently.

The present invention relates to a lower thread bobbin for a sewing machine able to hold a thread, the bobbin comprising a crescent moon-shaped winding part on which a thread can be wound and a crescent moon-shaped securing part for covering the winding part on which the thread has been wound. The lower thread bobbin for a sewing machine has the advantage of being able to hold a greater amount of a lower thread than the very limited amount of a lower thread that is wound on general conventional bobbins, and so increasing the efficiency of sewing work as the user or sewing machinist does not replace the bobbin frequently.

A bobbin holder that grasps a holder body and a flange of a bobbin that winds a thread n around the holder body, the holder including: an opening formed in an upper surface of the holder body; a thread holding portion that holds a thread n and is arranged in the opening so as to protrude from a center of the holder body toward an outer circumference of the holder body; and a cutting blade that cuts the thread held by the thread holding portion, the blade being disposed in one of regions inside the opening that is partitioned by the thread holding portion, wherein the cutting blade is disposed on a thread path of the thread n being pulled after the thread n, which is wound around the bobbin grasped by a grasping portion and is pulled from the other region inside the partitioned opening, is held by the thread holding portion.

A bobbin includes a bobbin main body including flanges at both ends of a bobbin winder spindle for winding the bobbin thread and an outer flange attached to one of the flanges (a second flange) of the bobbin main body. A gap in which a thread end of the bobbin thread is housed is provided between the outer flange and the flange of the bobbin main body.