摘要:
This invention makes a proper calculation to an amount of supplying a lower thread to be required to forming of a stitch with stitching information in relation with changing of a needle dropping position from a preceding stitch to a present stitching, so that the lower thread is forcibly drawn out in accordance with said calculation, and makes a proper calculation to tension of an upper thread optimum to forming of a stitch with stitching information so as to determine the optimum upper thread tension in accordance with said calculation, or makes a calculation to the amount of supplying the upper thread optimum to forming of a stitch with stitching information so as to draw out the upper thread in accordance with said calculation.
摘要:
A sewing machine with a vertically reciprocable and laterally swingable needle for sewing provided with an upper thread includes a rotatable loop taker for catching a thread loop during synchronous rotation thereof with the needle, and is rotatable in a horizontal plane with respect to the needle. A bobbin member is mounted within the loop taker and carries a lower thread forforming a lock stitch with the lower thread when the loop taker catches a thread loop. A feed dog member includes a plurality of feed dog elements for synchronously moving vertically and horizontally with the needle so as to allow the fabric to be moved relative to the needle. A thread guide is disposed adjacent a certain one of the plurality of feed dog elements for guiding the lower thread to a predetermined side of the swinging needle each time the feed dog member is vertically moved.
摘要:
A sewing machine comprises a thread deflecting device arranged between a thread take-up lever and a needle and which in response to a swinging movement of a needle bar effected in response to selection of a zigzag stitch, deflects the upper thread laterally of a fabric feeding direction. A thread blocking device is provided on one side of the thread deflecting device. The sewing machine further comprises an actuator operated in response to actuation of a zigzag stitch pattern selecting key to move the thread blocking device to an operative position thereof. The thread blocking device in the operative position blocks the upper thread as it is deflected in one direction by the thread deflecting device to give a predetermined degree of tension to the upper thread, so that the stitch is tightened on one side of the zigzag stitch in addition to the tightening of the stitch by a thread take-up lever.
摘要:
When a lower thread is effected with tension by an upper thread, a lower thread tension device is actuated in a certain working distance with very small resistance to an extent that a lower thread is drawn as if without resistance. If the lower thread is effected with said tension outside of said distance, it is not drawn out with large resistance. An actuation means successively receives information about thread consumed in each of the stitches and information about rotation phase of the sewing machine from a phase sensor. In the distance of a strong resistance, the lower thread is prohibited from drawing, and the thread is tightened in this distance.
摘要:
A thread tightening device for a sewing machine of the type having a main shaft, a vertically reciprocable needle bar with a needle carrying an upper thread, a loop taker and a drive shaft for driving the loop taker and a feed dog, the thread tightening device includes a group of pattern cams operatively connected to the main shaft, pattern selecting device and an arrangement for controlling the vertical movement of the feed dog. This arrangement comprises a control cam and a rotatable shaft, the control cam being slidably axially mounted on the rotatable shaft but not turnable with respect to the shaft. The thread tightening device also includes an element arranged for vertical reciprocating movement in a timed relation with the feed dog, which element engages a lower thread during the stitching operation of the sewing machine. A thread tension adjusting device is provided in the machine which comprises an adjusting cam operatively connected to the pattern cams and a linkage arrangement which is operatively connected to the adjusting cam and to the control cam to displace the control cam in the axial direction in response to a set position of the adjusting cam to thereby adjusting lower thread tension in accordance with the respective pattern cam.
摘要:
A sewing machine includes an automatic thread tension adjusting device comprising an upper thread tension member arranged in an a thread running path between an upper thread source and a main thread take-up lever. An auxiliary thread take-up lever is arranged in the upper thread running path between the main thread take-up lever and a needle holding the upper thread. A thread engaging part guides the upper thread. A thread presser is arranged laterally of the upper thread running path between the main and auxiliary thread take-up levers and normally clamps the upper thread. A detector detects a predetermined rotation phase of a drive shaft of the machine and thread elongation, respectively, and generates respective electric signals. A control circuit causes the thread presser to release the upper thread in response to the electric signals generated by the detector.
摘要:
A thread tightening device for a sewing machine of the type having a main shaft, a vertically reciprocable needle bar with a needle carrying an upper thread, a loop taker and a drive shaft for driving the loop taker and a feed dog; the thread tightening device includes a group of pattern cams operatively connected to the main shaft, pattern selecting device and an arrangement for controlling the vertical movement of the feed dog. This arrangement comprises a control cam and a rotatable shaft, the control cam being slidably axially mounted on the rotatable shaft but not turnable with respect to the shaft. The thread tightening device also includes an element arranged for vertical reciprocating movement in a timed relation with the feed dog, which element engages a lower thread during the stitching operation of the sewing machine. A thread tension adjusting device is provided in the machine, which comprises an adjusting cam operatively connected to the pattern cams and a linkage arrangement which is operatively connected to the adjusting cam and to the control cam to displace the control cam in the axial direction in response to a set position of the adjusting cam to thereby adjusting lower thread tension in accordance with the respective pattern cam.
摘要:
A lower thread drawing-out device for a computerized sewing machine, the device having a cup-shaped loop taker with a surrounding wall. The loop taker is rotatable in a timed relation with a vertical reciprocation of the needle to catch the upper thread to concatenate with the lower thread and thereby form lock stitches. A bobbin is arranged in the loop taker so as to form a space between the bobbin and the loop taker surrounding wall. A lower thread drawing out element having a free end in the space is arranged so that when a lower thread is wrapped around the bobbin and extends to a needle, the free end contacts the lower thread at a location. The lower thread drawing out element is rotatable relative to the loop taker. The lower thread is movable transversely at the contact location relative to the lower thread when extended and in response to a rotation of the element relative to the loop taker, thereby compensating for biasing of the lower thread.
摘要:
A tension setting device of the sewing machine comprises an upper thread tension device on the machine frame. A selecting device for selecting a thread tension in response to a thickness of a fabric being sewn is mounted to the machine frame. An auxiliary upper thread tension device cooperating with the selecting device and actuated thereby to adjust upper thread tension in response to the thickness of the fabric is provided in the tension setting device. A lower thread adjusting device cooperates with the thread tension selecting device to adjust the lower thread in response to the thickness of the fabric being sewn.
摘要:
For a hem stitching operation with a sewing machine having a needle vertically reciprocating and also laterally swingable, a hem stitching presser foot is detachably mounted to a lower end of a presser bar of the sewing machine. The presser foot includes a brush like element which confronts a needle dropping hole formed in a sole of the presser foot, a frictional contact between the needle and the brush like element is produced when the needle passes the outside of the fabric edge, without penetrating the fabric, to stitch a portion of hem stitches on the outside of the fabric edge. The brush like element may be secured to the sole of the presser foot, or alternatively to a fabric guide member for engaging and guiding the fabric edge. The brush may be projected in the fabric feeding direction or across the fabric feeding direction. A pin may be located just beneath the brush like element for constant placement thereof.