Abstract: A rotary hook (1) of a lockstitch sewing machine composed of at least one hook body (2) includes a cylindrical cavity (11) and a basket (6, 6b) free to rotate in the cylindrical cavity (11), a bobbin case (8, 8b) housed in the basket (6, 6b) and a bobbin (4, 4b) housed in the bobbin case (8, 8b), elements (30, 40, 50, 60, 61, 70,) suited to create a friction between the bobbin case (8, 8b) and the basket (6, 6b), so as to prevent the bobbin case (8, 8b) to move freely and to vibrate within the plays present between the bobbin case (8, 8b) and the basket (6, 6b) and to consequently reduce the noisiness created during the sewing operation.

Abstract: A stitching machine may include a needle apparatus, a sewing thread spool receiving device, and a bobbin thread spool receiving device. The stitching machine may further include a bobbin thread tensioner configured to receive bobbin thread from the bobbin thread spool receiving device. The bobbin thread tensioner may be further configured to supply the bobbin thread to the needle apparatus. The bobbin thread spool receiving device is configured to receive a bobbin spool holding approximately 700 meters or more of bobbin thread. The bobbin thread spool receiving device may be located above a stitching location of the stitching machine. The stitching machine may provide improved access to a bobbin spool, enhanced manufacturing efficiency, and enhanced manufacturing flexibility.

Abstract: There is provided a sewing-machine bobbin thread tension controller capable of elaborately, accurately controlling bobbin thread tension without depending on frictional force. A bobbin thread tension controller includes an outer shuttle, a middle shuttle presser, a middle shuttle, a bobbin thread tension control mechanism, a shuttle actuation unit, and a bobbin. The middle shuttle has a magnet. A magnet is disposed, in close proximity to the magnet, on an arm attached to a rotary shaft of a shuttle actuation motor provided in the shuttle actuation unit. The middle shuttle is rotated by rotating the magnet by means of the motor. Further, a rotary disc is provided, in close proximity to the middle shuttle, on a rotary shaft of a bobbin thread tension control motor of the bobbin thread tension control mechanism and is provided with a magnet. A magnet is disposed on a part of the bobbin facing the rotary disc.

Abstract: There is provided a sewing-machine bobbin thread tension controller capable of elaborately, accurately controlling bobbin thread tension without depending on frictional force. A bobbin thread tension controller includes an outer shuttle 110, a middle shuttle presser 130, a middle shuttle 150, a bobbin thread tension control mechanism 200, a shuttle actuation unit 250, and a bobbin 300. The middle shuttle 150 has a magnet 190. A magnet 270 is disposed, in close proximity to the magnet 190, on an arm 260 attached to a rotary shaft of a shuttle actuation motor 252 provided in the shuttle actuation unit 250. The middle shuttle 150 is rotated by rotating the magnet 270 by means of the motor 252. Further, a rotary disc 210 is provided, in close proximity to the middle shuttle 150, on a rotary shaft of a bobbin thread tension control motor 202 of the bobbin thread tension control mechanism 200 and is provided with a magnet 214. A magnet is disposed on a part of the bobbin 300 facing the rotary disc 210.

Abstract: The present invention provides a bobbin thread feeder of sewing machine of simple structure in which a lower thread can be reliably fed at an appropriate tension. A lower thread bobbin 21 can be removably contained through an opening for containing a lower thread bobbin 17 in a rotary hook 20 of a horizontal rotary hook 30 provided in a sewing machine frame. A thread tension plate and a thread tension spring are attached while overlapping along the inner circumference of the rotary hook 20, and function as a tension generating portion 22 for imparting resistance to pulling out a lower thread being guided through the gap between the thread tension plate and the thread tension spring. A needle plate 16 with an opening for taking the lower thread bobbin 21 in and out is provided above the rotary hook 20. The needle plate 16 comprises a guiding slit 27 that guides the lower thread formed thereon.

Abstract: A bobbin case assembly having a wall structure mountable upon a support, a bobbin for a supply of thread, and a tensioning element for engaging thread projecting from a supply of thread on the bobbin. The tensioning element has a length and a circumferential surface against which thread can be wrapped so that a frictional resistance force can be generated between the thread and circumferential surface that resists drawing of thread off of the supply. The tensioning element has a configuration that limits lengthwise shifting of a spirally wrapped portion of thread wrapped against the circumferential surface.

Abstract: A bobbin case assembly having a wall structure mountable operably upon a support and defining a first receptacle for a supply of thread, and a tensioning assembly. The tensioning assembly has a first surface that bears against the thread. At least one of the wall structure and tensioning assembly has a second surface. The thread resides between the first and second surfaces through which the frictional force on the thread is generated. A body is bendable to so that one of the first and second surfaces is movable selectively towards and away from the other. A flexing portion on the body is bendable relative to mounting portion and has first and second flexing regions. The second flexing region is more flexible relative to the first flexing region than the first flexing region is flexible relative to the mounting portion. The first surface is on the second flexing region.

Abstract: The combination of a bobbin assembly and a support for the bobbin assembly. The bobbin assembly has a core around which a supply of thread can be wrapped. The core has a rotational axis. The bobbin assembly further has a first flange with first and second oppositely facing surfaces. The first surface bounds a storage space for thread wrapped around the core. The first flange has at least one projection from the second surface. The support has a third surface facing the second surface and bearing against the at least one projection for limiting movement of the spool in a direction substantially parallel to the rotational axis with the bobbin assembly operatively connected to the support.

Abstract: The combination of a bobbin assembly and a support for the bobbin assembly. The bobbin assembly has a core around which a supply of thread can be wrapped and having a rotational axis, a first flange having first and second oppositely facing surfaces with the first surface bounding a storage space for thread wrapped around the core, and a magnetic element. The support has a third surface with a first metal material facing the second surface with the bobbin assembly operatively connected to the support and sufficiently close to the magnetic element so that a magnetic field is generated between the magnetic element and first metal material that tends to resists movement of the bobbin assembly relative to the support around the rotational axis of the core.

Abstract: The combination of a bobbin case assembly and a supply of thread. The bobbin case assembly has a wall structure defining a receptacle for the supply of thread and a thread tensioning assembly on the wall structure including a thread tensioning element. The supply of thread projects from the receptacle and is wrapped at least partially around the thread tensioning element so as to produce resistance to the removal of the thread from the receptacle.

Abstract: A bobbin-thread supply device for a sewing machine. The operator inserts the bobbin into the bobbin holder, draws bobbin thread from the bobbin, and passes the tip of the bobbin thread through the slit in the cover above the bobbin holder. Since the slit in the cover extends above where the tension bracket is joined onto the tension spring, the bobbin thread is guided between the tension bracket and the tension spring through the tension regulating portion. The bobbin thread can thus easily be set with appropriately tension applied thereon. At the same time, the length of the bobbin thread can be adjusted for proper sewing operation.

Abstract: In a thread trimmer mechanism on a sewing machine, a movable knife for catching and cutting thread and a bobbin pressing member for pressing and applying frictional resistance to a bobbin are operated synchronously with a rotary hook assembly. After needle thread caught by a hook of the rotary hook assembly has passed the end surface of the bobbin, the bobbin pressing member presses the end surface of the bobbin. Therefore, the needle thread is prevented from being caught in the bobbin pressing member and from being excessively supplied. Almost at the same time as the bobbin pressing member presses the end surface of the bobbin, the movable knife catches and cuts the thread. Consequently, even when the movable knife pulls bobbin thread from the bobbin, the bobbin is prevented from spinning freely. As a result, only a short thread extends from the last stitch on cloth, thus enhancing the appearance of the cloth and possibly eliminating a separate trimming operation.

Abstract: A rotary looper for a lockstitch sewing machine, which can receive either a coreless thread package or a thread-wound bobbin. An upper bobbin-housing part is provided with two separate thread-tensioning elements and with respective thread-guide slots associated with them. In this way, the thread withdrawn either from a coreless thread package or a looper-thread bobbin passes over an optimally-shaped thread path on its way to the sewing area, and in both cases, a specifically adapted thread-tensioning force is exerted on the thread withdrawn. Preferably, the front part of the thread supply, in the coreless package or bobbin, can be accommodated in front of the movement path of the sewing needle, whereby the bobbin-housing can accommodate an extra-wide thread supply. An upwardly extended shoulder is provided on the lower part of the bobbin housing, so that the axially widened needle thread loop can slide unimpeded over the axially-extended bobbin-housing upper part.

Abstract: A lower thread tension adjusting device for a sewing machine comprising first and second tension arrangements mounted on a bobbin carrier of the sewing machine for tensioning a lower thread with a predetermined tension and a predetermined additional tension, respectively. A positioning device is mounted on the bobbin carrier and movable between first and second set positions in which the positioning devices moves the second tension arrangement to operative and inoperative positions wherein the second arrangement provides and does not provide the predetermined additional tension of the lower thread. A guide assembly guides the lower thread to positions adjacent to one end and a center of a laterally elongated needle hole and simultaneously guides the positioning device to the first and second positions thereof. A control unit moves the guide assembly between first and second guide positions thereof in accordance with selected patterns of straight and zigzag stitches, respectively.

Abstract: In a sewing machine provided with a thread supply stopping device for selectively controlling supply of a needle thread between a needle thread supply source and a take-up lever, an adjustable pre-tension exerting device exerts a tension equal to or lower than a tension of a bobbin thread on the needle thread between the needle thread supply source and the thread stopping device.

Abstract: A bobbin case wherein a cylindrical wall which surrounds the thread bobbin supports an externally mounted spring having a pan-shaped portion for a disc-shaped thread tensioning member provided with a flat thread-contacting surface which confronts a complementary portion of the external surface of the cylindrical wall. The bias of the spring upon the tensioning member, and hence the force with which the surface of the tensioning member urges the thread against the adjacent portion of the external surface of the cylindrical wall, is adjustable by a screw. The tensioning member is tiltably installed in the pan-shaped portion of the spring so as to adjust its inclination relative to the adjacent portion of the external surface of the cylindrical wall in dependency on the position of the thread.

Abstract: An opening plate which closes a lower thread bobbin is provided with a drawing of a bobbin on its surface. A bobbin drawing is exactly overlapped with the bobbin when the plate is completely closed. Also a drawing of a thread tension adjusting device in a required position and a drawing of a lower thread normal path are provided on the opening plate. The drawings indicate to a machine operator the position of lower thread holding bobbin correctly inserted in a horizontal full rotation loop taker device and the path of drawing of the lower thread therefrom so as to enable the operator to insert the lower thread holding bobbin in the horizontal full rotation loop taker device correctly in place, and pass the lower thread wound on the bobbin through the thread tension adjusting device correctly.

Abstract: A lower thread tension device is provided in association with adjustment of an upper thread tension device in such a manner that when the tension of the upper thread tension device is strong within an adjusting range, the lower thread tension is adjusted strongly, and when the tension of the upper thread tension device is weak within the adjusting range, the lower thread tension is adjusted weakly. The upper and lower thread tension device includes a dial for adjusting an upper thread tension, a potentiometer connected to the dial, and an electromagnet with an actuator acting on the lower thread to adjust its tension in response to a signal received from the potentiometer due to rotation of the dial. The upper and lower thread tension device includes a dial for adjusting an upper thread tension, a potentiometer connected to the dial, and an electromagnet with an actuator acting on the lower thread to adjust its tension in response to a signal received from the potentiometer due to rotation of the dial.

Abstract: 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.

Abstract: A thread-tensioning device for being mounted on a bobbin housing, the bobbin housing having an upper part and a lower part which define a space for receiving a bobbin, and a jacket for substantially surrounding the bobbin. The thread-tensioning device includes a thread-tensioning member, such as a lever, having a first end swingably supported on the upper part of the housing, and a second end comprising a finger for bearing on the thread package on the bobbin. A central part of the lever is received by a slot in the jacket of the bobbin housing. A leaf spring bears upon the lever to urge the finger toward the interior of the bobbin-receiving space and against the thread package. The arrangement produces a detaining force and a braking force which combine to result in a relatively constant thread-tensioning force.

Abstract: 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.

Abstract: A rotary hook for a sewing machine has a rotatable hook drive shaft driving a hook body in cooperation with a reciprocating needle which moves toward and away from the rotary hook. The hook body has a revolving rotary hook tip which is movable in a path relative to the needle and is engageable with the thread presented by the needle. The rotary hook includes a thread deflecting shoulder to enlarge the thread to form a needle thread loop, includes a case holder having an annular guide rib and a pin extending axially outwardly of the holder. A bobbin case has a central hollow sleeve into which the pin extends and a latch engageable with the pin to hold the case holder to the bobbin case. The case each holder and the bobbin case have a sidewall with interiors which are in substantial alignment. The bobbin case holder has a rearwall formed as a substantially truncated cone which is eccentric to the guide rib and the bobbin case has an annular sidewall and a frontwall have an arched mushroom shape.

Abstract: A lower thread tension adjusting device is disclosed, which is used in combination with a sewing machine having a horizontal rotary loop taker and a stationary bobbin carrier accomodating a bobbin. A lower thread drawn from the bobbin is passed between a base plate secured to the outer face of the bobbin carrier and the free end of a resilient plate having one end secured to the base plate, so that by manipulation of an adjusting screw a variable degree of tension can be applied to the lower thread. The device is so designed that when an index provided on the adjusting screw is in alignment with a reference mark of the base plate, the lower thread will be given a predetermined standard value of tension.

Abstract: A sewing machine has a loop taker rotated in horizontal plane and a bobbin carrier contained in the loop taker. The bobbin carrier has an abutment secured thereto and a leaf spring mounted on the abutment and movable to and away from the abutment to adjust a tension applied to a lower thread extending between the abutment and the leaf spring. A plurality of windings are provided on a stationary horizontal plane adjacent the underside of the loop taker. The windings are progressively energized by selective operation of an electric control part to create a revolving magnetic field. A magnet is rotated in accordance with the revolving magnetic field, and the rotation of the magnet is transmitted through a series of gears to a cam which actuates a member influencing the movement of the leaf spring, thereby adjusting the tension applied to the lower thread.

Abstract: A sewing machine having a drive shaft rotated by a machine motor to vertically reciprocate a needle carrying an upper thread is provided with a device for adjusting the tension of a lower thread pulled out from a bobbin located in a bobbin carrier of the sewing machine. The device includes a tension lever cooperated with a spring element, and a releasing lever which is in engagement with a cam rotated by the drive shaft. The position of the tension lever relative to the lower thread is effected by a manually operated dial and a cam engageable with the spring element. The releasing lever is adapted to intermittently release the tension lever from the lower thread during the stitching operation.

Abstract: A non-spill bobbin case device having a bobbin thread tension spring and a direct bobbin thread path extending from the bobbin thread tension spring across the bobbin case device spaced from the outer face of a bobbin flange supported in the bobbin case, and having a leaf spring with a first end attached thereto, the second end of which impinges upon the outer face of the bobbin flange. An indirect thread path is established by reeving the bobbin thread through a hook provided on the end of the leaf spring in engagement with the bobbin flange so that upon thread demand, the leaf spring is removed from the bobbin flange to permit free rotation thereof; but when thread demand ceases, the end of the leaf spring comes immediately into contact with the bobbin flange to deter further rotation thereof.

Abstract: An assembly for adjustment of lower thread tension for a sewing machine having a loop taker and a bobbin carrier which is held by the loop taker and carries a bobbin loaded with the lower thread. The assembly comprises a base plate and a resilient member, one end of which is connected to the base plate. A tension is given to the lower thread while the thread is passed between the base plate and the resilient member. A substantially L-shaped presser element having an upper vertical and a lower horizontal portion is provided for the assembly and is turnably attached to an inner wall of the bobbin carrier. The vertical portion of the presser element is adapted to press a free end of the resilient member against the base plate. A permanent magnet or electromagnet acts on the horizontal portion of the presser element without contact thereto.

Abstract: A bobbin case for a lockstitch sewing machine is disclosed which contains a thread control lever so constructed to allow the bobbin to be manually threaded from any direction without incurring the possibility of snagging the bobbin thread between the wall of the bobbin case and the thread control lever. One extremity of the thread control lever is pivotally mounted in a race formed in the wall of the bobbin case. The free extremity of the thread control lever, which is spring biased toward the bobbin, is shaped to form an obtuse angle with the wall of the bobbin case. Bobbin thread is thereby prevented from snagging between the bobbin case wall and the thread control lever.

Abstract: A bobbin thread control comprising a bobbin thread pull-off, carried by a rotating lockstitch looptaker to pull bobbin thread from a bobbin after the previous stitch has been set and having a retraction element variable in its rotational position on the looptaker for enabling selective retraction of bobbin thread from the setting stitch.

Abstract: A device for automatically adjusting the tension of a lower thread, which comprises a lower thread bobbin arranged on a bottom plate of a bobbin carrier turnably carrying the bobbin, a loop taker mounted on a magnetic shaft, and an energizing coil arranged around the magnetic shaft and providing together with said bottom plate and magnetic shaft a path of magnetic flux. The device is further provided with a detector detecting the consumed amount of the bobbin thread and a control circuit for energizing the coil when the lower thread is wound to the maximum capacity of the bobbin, interrupting the light of the detector. The detector operates the control circuit to decrease the amount of electric current applied to the energizing coil so as to set the lower thread tension back to its initial predetermined value.

Abstract: A bobbin thread tensioning device on a bobbin case is provided with a pair of bobbin thread accepting members, one of which is biased toward the other by an adjustable spring. The thread accepting members are disposed relative to each other and with respect to a rotatable hook to assure seizure of the bobbin thread by the hook beak.

Abstract: A bobbin case for use in machines having underbed thread trimmers incorporates a thread guide consisting of a piano wire soldered to the cylindrical skirt of the case in the region between the leaf tension spring and the point at which the thread is cut by the trimming blade. A groove is formed under and partly through the wire and also partly through the cylindrical skirt. The groove is directed at an angle to the longitudinal direction of the skirt such as to place the groove in line with the direction of movement of the thread to facilitate smooth thread handling.

Abstract: A bobbin thread tension for a closed end cylindrical body bobbin thread case of a horizontal axis type rotary hook for a lockstitch sewing machine consisting of a diagonally slotted thread aperture in the wall of the bobbin case partially covered by a bobbin thread control that is adjustably mounted on the wall of the bobbin case by a pivot screw at one of its ends and inward a clamp screw passing through an enlarged hole in the bobbin thread control allowing the control to be pivoted to cover an effective amount of the thread aperture thereby increasing or decreasing the bobbin thread tension.

Abstract: An annular disc is forced onto the central sleeve of the sewing machine bobbin case and held in place by the tight interference fit. A set screw within the limited area of the front wall, thick enough to hold the entire length of the screw, can be adjusted from outside the bobbin case to set the braking pressure of the disc against a bobbin flange to prevent excessive rotation of the bobbin and spillage of its thread.

Abstract: Spool case for sewing machines having devices for adjusting the braking spring of the thread spool. The case comprises a front wall and a cylindrical skirt portion defining a cavity or recess accommodating a thread spool; a flat spring for spool braking is secured internally on the front wall of the case and a screw acts upon the spring to adjust the braking pressure thereof. Between its securing location to the case and its contact location with the pressure adjusting screw, said braking spring has a projection or lug engaging with the case skirt.

Abstract: A bobbin and gripper assembly for a double-lock-stitch sewing machine has a stitch plate lying in a horizontal plane and a gripper rotatable in a horizontal plane below the stitch plate and receiving a bobbin housing. The latter is provided with a retaining finger which cooperates with abutments formed on the underside of the stitch plate to retain the bobbin housing against rotation with the gripper. In addition, the bobbin housing is held by a spring member which is effective to yieldably retard the bobbin against rotation in the direction of rotation of the gripper by friction therewith.

Abstract: A bobbin case for sewing machines, in which a thin plate spring operates on the bobbin for inhibiting rotation thereof wherein an adjustable screw acts upon the spring to regulate the pressure on the bobbin and means is provided for exerting a constant thrust on the adjusting screw in a direction at a right angle to its axis for preventing it from loosening.

Abstract: A controlled braking device for the gripper-thread bobbin of a double lock-stitch sewing machine has a braking element which, by means of a brake piston or plunger in the axial bore of the spindle carrying the bobbin, is shiftable to engage the latter. The plunger is engaged by a rod reaching upwardly through an opening in the bottom of the spindle. The brake element is displaced laterally into engagement with the core of the bobbin or axially thereagainst.

Abstract: To control thread pull-off, particularly in high-speed industrial sewing machines, a rotatable element such as a roller pin is engaged with the bobbin, typically with the outside flange of the bobbin. The pin is rotated, upon spinning of the bobbin, and restrained from free rotation by a spring bearing against the pin. Preferably, the pin is formed with drum or bell-shaped ends, the spring being similar to a bobbin case retaining spring and bearing against a reduced diameter thereof, to provide for different diameters of engaging rotating surfaces between flange and pin, as well as between the flange engaging surface and the spring engaging pin.