摘要:
A device for changing a lower thread running path in a zigzag sewing machine includes a guiding member positioned between a lower thread holder and a needle plate and having an obliquely positioned guiding face the obliquity of which to the direction of the needle amplitude is controlled to selectively produce straight stitches or zigzag stitches.
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:
An automatic thread tensioning device for positioning the crossing points of upper and lower threads in the center of thickness of a fabric undergoing stitching. The positioning is effected by making calculations based on measured results of thread tension, without needing to detect the various kinds of characteristics of fabrics, threads, or lower thread tension responding to an existing type of stitching condition. The proper upper thread tension may be determined for the stitching conditions of fabrics which have different characteristics and for stitching conditions of fabrics which have conventionally been difficult to deal with, simply by pressing buttons and making test stitchings. If an upper thread tensioning device has a motor, a stitching operation may be made more easily.
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 device for guiding a lower thread in a zigzag stitching sewing machine is provided with a lower thread guiding unit that determines two lower thread drawing positions in accordance with a selected pattern. The lower thread guiding unit includes a lower thread guiding part which, at one of the two positions, acts on the lower thread to guide a lower thread drawing position to a center of a needle amplitude. A lower thread releasing element, at the other of the two positions, cooperates with the lower thread guiding unit to release the lower thread engaged with the lower thread guiding part.
摘要:
An automatic thread tension control sewing machine comprising thread tension controller for clamping an upper thread with a predetermined pressure to control an amount of the upper thread supplied to a needle and a loop taker, thread tension setting means that determines a pressure with which the thread tension controller clamps the upper thread, upper thread supplying mechanism, a releasing mechanism controlling operation of the upper thread supplying mechanism, and a central processing unit for actuating the releasing mechanism in accordance with a selected stitch pattern.
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 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.