The present invention provides a thread feeding device of a decorative stitching sewing machine. The thread feeding device feeds a needle thread, an upper looper thread, and a lower looper thread in the amounts required for sewing one stitch such that the position of a stitch looping point of the threads changes. The thread feeding device includes: a thread accumulator 500 having thread accumulating elements 13a to 13d and 14a to 14d which measure the thread accumulation amounts of predetermined lengths of the needle thread, the upper looper thread, and the lower looper thread, and thread accumulation amount control elements 15 to 18 which adjust the amounts of the threads required for sewing one stitch in an increasable and decreasable manner within the range of thread accumulation amounts of predetermined lengths at the time of fabric feeding, and which release the threads to a stitch forming device when a stitch is formed; a thread feed drive mechanism 600 which drives each of the elements; and a thread feed control unit having a program which dives the thread accumulation amount control elements for each stitch to feed the threads in an increasable and decreasable manner so as to increase or decrease the threads within the range of a total thread feeding amount that is maintained constant, including a fabric feeding amount, a fabric thickness and an overlocking width, thereby to change the position of the stitch looping point of the needle thread, the upper looper thread, and the lower looper thread, thus controlling the decorative stitching according to a stitching decoration pattern.

The present invention relates to a structure for fastening composite structures, and more particularly, to a sewing machine for stitching composite materials which is capable of automatically and continuously stitching the composite structures by using a high-rigidity fiber in order to laminate and join the composite materials. The sewing machine for stitching composite materials according to the present invention automatically and continuously performs a stitching operation for joining composite materials by using a high-rigidity composite fiber for joining the composite materials, and as a result, it is possible to reduce process time for joining the composite materials and improve productivity.

The present invention relates to a structure for fastening composite structures, and more particularly, to a sewing machine for stitching composite materials which is capable of automatically and continuously stitching the composite structures by using a high-rigidity fiber in order to laminate and join the composite materials. The sewing machine for stitching composite materials according to the present invention automatically and continuously performs a stitching operation for joining composite materials by using a high-rigidity composite fiber for joining the composite materials, and as a result, it is possible to reduce process time for joining the composite materials and improve productivity.

A lower thread supply device of a sewing machine includes a bobbin, a bobbin case, a magnetic force member, and a magnetic force change portion. The bobbin has a cylindrical portion for inserting into a spindle of a shuttle, a shuttle side flange portion, and a front surface side flange portion which is magnetic, and a lower thread is wound around an outer circumference of the cylindrical portion between the shuttle side flange portion and the front surface side flange portion. The bobbin case has a non-magnetic cover portion having a front surface side part and a side wall part, housing the bobbin and transmitting a magnetic force. The magnetic force member is arranged at the front surface side of the bobbin case and attracts the front surface side flange portion of the bobbin by a magnetic force via the bobbin case.

A lower thread supply device of a sewing machine includes a bobbin, a bobbin case, a magnetic force member, and a magnetic force change portion. The bobbin has a cylindrical portion for inserting into a spindle of a shuttle, a shuttle side flange portion, and a front surface side flange portion which is magnetic, and a lower thread is wound around an outer circumference of the cylindrical portion between the shuttle side flange portion and the front surface side flange portion. The bobbin case has a non-magnetic cover portion having a front surface side part and a side wall part, housing the bobbin and transmitting a magnetic force. The magnetic force member is arranged at the front surface side of the bobbin case and attracts the front surface side flange portion of the bobbin by a magnetic force via the bobbin case.

A sewing machine includes a thread tension mechanism, a thread feed sensor, a sewing portion, a processor, and a memory. By executing instructions stored in the memory, the processor causes a first tension to act on an upper thread by the thread tension mechanism to be in a first state, in a state in which a sewing is stopped. The processor causes a second tension that is smaller than the first tension to act on the upper thread, by causing the thread tension mechanism to be in a second state, when the movement of the upper thread is detected by the thread feed sensor. The processor causes a third tension that is equal to or greater than the second tension to act on the upper thread by causing the thread tension mechanism to be in a third state, in a state in which the sewing is performed.

A sewing machine includes a thread tension mechanism, a thread feed sensor, a sewing portion, a processor, and a memory. By executing instructions stored in the memory, the processor causes a first tension to act on an upper thread by the thread tension mechanism to be in a first state, in a state in which a sewing is stopped. The processor causes a second tension that is smaller than the first tension to act on the upper thread, by causing the thread tension mechanism to be in a second state, when the movement of the upper thread is detected by the thread feed sensor. The processor causes a third tension that is equal to or greater than the second tension to act on the upper thread by causing the thread tension mechanism to be in a third state, in a state in which the sewing is performed.

A sewing machine includes a first image acquisition unit, a second image acquisition unit, and a display unit. In the sewing machine, the first image acquisition performs image acquisition from the front face side of a cloth for a stitching pattern formed in the cloth. The second image acquisition unit performs image acquisition from the back face side of the cloth such that the center position of the acquired image matches the center position of the image of the stitching pattern acquired by the first image acquisition unit. The display unit displays, on the same screen, a first stitching pattern video image thus acquired by the first image acquisition unit and a second stitching pattern video image thus acquired by the second image acquisition unit.

A sewing machine includes a first image acquisition unit, a second image acquisition unit, and a display unit. In the sewing machine, the first image acquisition performs image acquisition from the front face side of a cloth for a stitching pattern formed in the cloth. The second image acquisition unit performs image acquisition from the back face side of the cloth such that the center position of the acquired image matches the center position of the image of the stitching pattern acquired by the first image acquisition unit. The display unit displays, on the same screen, a first stitching pattern video image thus acquired by the first image acquisition unit and a second stitching pattern video image thus acquired by the second image acquisition unit.

A sewing machine that suppresses sewing defects is provided. The sewing machine includes: a sewing needing, held by a needle bar and moving back and forth while holding an upper thread: a shuttle, configured to hold a bobbin which is housed in a bobbin case and around which a lower thread is wound, and cooperating with the sewing needle to form a seam; a presser foot member, configured to press a to-be-sewn article at a sewing position directly below the sewing needle: a pressure adjustment portion, adjusting pressure applied to the to-be-sewn article by the presser foot member; a feeding mechanism, where endless feeding belts for feeding the to-be-sewn article from the sewing position to a first direction are disposed on two sides of a second direction orthogonal to a first direction with respect to the sewing position, the feeding mechanism is provided with a belt drive portion, and the belt drive portion independently drives the feeding belts on one side of the second direction with respect to the sewing position and the feeding belts on another side of the second direction with respect to the sewing position; and a control portion, configured to control the pressure adjustment portion to make a pressure of the presser foot member be corresponding to a difference between a feeding amount of the feeding belts on one side of the second direction with respect to the sewing position and a feeding amount of the feeding belts on another side of the second direction with respect to the sewing position.