JPH06277380A - Needle thread tension control device for sewing machine - Google Patents

Abstract

PURPOSE:To eliminate a complicated needle thread applying device regulate thread tension of needle thread easily and speedily, and supply only a necessary quantity of the needle thread by setting the lowest drop point of an eccentric outer wheel of an eccentric cam fixed at an upper shaft to be freely rotatably to coincide with an upper dead point of a needle thread take-up. CONSTITUTION:An actuation rod 46 having a root part 47 to be applied to an eccentric outer wheel 72 of an eccentric cam 71 of a machine upper shaft 50 is disposed in a cylindrical body 58 to move up and down freely, and a first coil spring 54 is wound around the actuation rod 46 between thread tension nuts 48, 49 and thread tension discs 52. A second coil spring 60 is wound around the actuation rod 46 between a head part 56 of the cylindrical body 58 and the root part 47 of the actuation rod 46, so the actuation rod 46 is capable of elevation freely within a range of a slit 62 in the cylindrical body 48. In addition, the lowest drop position of the eccentric outer wheel 72 is actuated to be applied to the actuation rod root part 47 to compress a coil spring 60, while the coil spring 54 is pushed up simultaneously, thereby pressure between the thread tension discs 52 in reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle thread tension controller for a sewing thread of a sewing machine. More specifically, the present invention relates to a needle thread tension control device for a sewing machine that works in conjunction with an eccentric cam on the upper shaft of the sewing machine.

[0002]

2. Description of the Related Art A conventional sewing thread (upper thread) adjusting device for a sewing machine is attached with reference to FIGS.
Will be explained. First, the needle thread T that has passed through the hole 6 of the thread guide rod 4 provided upright on the sewing machine head 2 passes through the thread guide piece 8 and the other thread guide 10 provided on the side surface of the head 2, and the needle thread adjusting device. 12 are supplied. An example of the structure of the needle thread adjusting device 12 is as shown in FIG. Pedestal 3 of sewing machine head 2
A vertical groove 16 is bored in the support nut 14 projecting from the upper end of the support nut 14, and a thread take-up spring 20 having a curved end portion 21 on the head 2 side and a pair of thread tension discs 18, 19 are fitted into the support nut 14. Insert the thread tension spring 15 on the outside of the support nut 1
A pair of thread tension discs 18 and 19 are screwed into the thread tension discs 4 and 19.
And the upper thread T held by the end curved portion 21 of the thread take-up spring 20 is tightened, and the upper thread T and the thread tension disc 18,
The degree of contact with 19 was adjusted and the required thread tension was set.

The needle thread T passing through the needle thread adjusting device 12 is a hole 13 of a balance 24 which is attached to the upper shaft of the sewing machine so as to be vertically movable.
After passing through the thread guide 34, the thread guides 26, 28 provided on the face plate 25 of the sewing machine head 2 are passed through the thread guide 34 provided on the needle stopper 31 for attaching the needle 32 to the needle bar 30, and the needle 32
Is inserted into the needle hole 36 of the. Reference numeral 38 is a balance wheel provided at the end of the upper shaft of the sewing machine, and a belt wound around the balance wheel normally drives the upper shaft and the lower shaft of the sewing machine to be connected to each other. Also code 3
9 is a bed of the sewing machine head 2. By driving the upper shaft,
As described above, the thread guide groups 8 and 10, the needle thread adjusting device 12,
Hole 13 of balance 24 and another thread guide group 26, 28, 3
The upper thread T supplied to the needle hole 36 of the needle bar 32 through 4 moves up and down together with the needle 32 attached to the needle bar 30, and is drawn out from the hook 40 arranged below the sewing machine bed 39. In cooperation with the needle bar 30, a so-called lock stitch is formed on the cloth placed on the lower sewing machine bed 39 of the needle bar 30 and fed forward. In the above operation, when the upper thread T and the lower thread T'supplied are sutured and the thread tension of either thread is too strong or too weak, the upper and lower threads are properly balanced and formed. Will be difficult. In order to correct this, the comb 40 is adjusted to adjust the feeding of the bobbin thread T ', or the interval between the thread tension discs 18 and 19 of the needle thread adjusting device 12 is fitted or widened by the operation of the screw 22. The purpose is achieved by adjusting the tension of the needle thread T supported by the curved end portion 21 of the thread take-up spring 20.

The thread take-up spring 20 which is involved in the formation of the seam cooperates with the balance 24 and plays an important role of controlling the tension of the upper thread. First, when the balance 24 and the needle 32 are at the top dead center, the needle thread T has a proper amount for the end curved portion 21 of the thread take-up spring 20 (this curved portion 21 is called a pin pin in field terms) and the balance 24. Tension is applied. The balance 24 descends together with the needle 32, and when the needle 32 penetrates through the cloth, the thread take-up spring end curved portion 21 temporarily stops its operation, the upper thread T is loosened, and is hooked on the protrusion of the hook 40. It rotates around it and is entangled with the bobbin thread T '. Next, when the needle bar 30 is raised to pull up this bobbin thread,
The balance 24 also rises in synchronization with this in order to pull up the lower thread T ′ together with the upper thread T. At this time, in order to make it easy for the thread to come off from the hook 40, the thread take-up spring end curved portion 2
No. 1 exerts a strong tension on the yarn due to its elastic force. This state continues until the balance 24 pulls up the thread and reaches the top dead center. In other words, the thread take-up spring end curved portion 21 is always the balance 2
4. The tension of the thread is controlled in synchronization with the movement of the needle bar 30 to contribute to the correct formation of the lock stitch. Therefore, once the thread take-up spring 20 is out of timing with the other members involved in the seam formation, it may cause a problem such as puckering, so that the operator must be very careful when adjusting the thread take-up spring 20. It was

[0005]

The above-mentioned conventional needle thread adjusting device not only requires a complicated structure, but also operates the needle thread adjusting device and the thread guide, especially the curved end portion of the thread take-up spring. There is a problem that it requires a considerable amount of skill in order to adjust the thread tension of the upper thread and the lower thread satisfactorily, and it is also caused by the difference in the kind of cloth and the count of the thread used for stitch formation. Therefore, it was difficult to adjust the thread tensions to the exact condition each time. The present invention eliminates a complicated needle thread adjusting device including a thread take-up spring and the like, and provides a thread tension control device capable of easily and quickly adjusting the thread tension of a sewing thread, particularly an upper thread, and supplying a necessary amount of the sewing thread. With the goal.

[0006]

According to the present invention, in order to achieve the above-mentioned object, the sewing machine is directly attached to the upper shaft of the sewing machine instead of the outer surface of the sewing machine head, that is, this is attached to the sewing machine head. A needle thread tension control device for a sewing machine, which is housed in a part or serves as an accessory by itself.
An operating rod (46) having a root portion (47) capable of contacting an eccentric outer ring (72) of an eccentric cam (71) provided on a sewing machine upper shaft (50) is arranged in a tubular body (58) so as to be vertically movable. Then, the thread tension nuts (48) and (49) and the thread tension tray (52, 52).
The first coil spring (54) is wound around the outer periphery of the actuating rod (46) so as to extend between the cylindrical body (58) and the coronal head (5).
6) and the operating rod (46) root (47) between the operating rod (4)
6) Wrap the second coil spring (60) around the outer periphery,
A long hole (6) in which the actuating rod (46) is formed in the tubular body (58).
It can be moved up and down within the range of 2) so that when the upper shaft (50) of the sewing machine rotates, the lowest descent position of the eccentric outer ring (72) of the eccentric cam (71) and the top dead center of the balance (24) match. It is a needle thread tension control device (44) of the sewing machine configured as described above. Further, there is provided a thread guide (41) for supplying the upper thread (T) from the bobbin to the thread tension tray (52, 52) through the coil spring (43) and the support plate (42) fitted to the tubular body 58. I am.

[0007]

By operating the thread tension nut, the degree of contact between the pair of thread tension discs can be adjusted, and at the same time, the actuating rod contacting the eccentric cam is displaced in accordance with the rotational position of the eccentric cam to displace the second coil spring. The degree of contact between the pair of thread tension discs can be adjusted by utilizing the change in the elastic force with the first coil spring. At the time of upper shaft rotation, the lowest position of the eccentric outer ring of the eccentric cam and the top dead center of the balance are aligned so that when the balance is at the top dead center, the needle thread will be between the tension discs. It is easier to pull out, and this state is released as the balance descends, and the sewing thread attached to the needle makes it easier to entangle with the lower thread from the kama arranged below the sewing machine bed, and the balance moves up to To make it easier to pull out the thread,
It gives an appropriate tension to the yarn. That is, the upper thread necessary for seam formation is sequentially supplied, which is useful for smooth seam formation.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, the needle thread tension control device 44 has a root portion 47 having a larger diameter than the upper end at the lower end of the operating rod 46, and a screw portion 45 formed on the outer periphery of the upper end of the operating rod 46. A pair of thread tension nuts 48, 4 that can be screwed together
9 is provided. Thread tension discs 52, 52 engaged with the operating rod 46
Between the thread tension nuts 48 and 49 and the operating rod 4
6. The first coil spring 54 is wound around the outer circumference. A tubular body 58 provided with a screw portion 57 on the outer periphery is provided in contact with the lower end of the thread tension disc 52, and the crown-shaped head portion 56 is fixed to the upper end of the tubular body 58. A second coil spring 60 is wound around the outer periphery of the operating rod 46 so as to extend between the operating rod 46 below the coronal head portion 56 of the tubular body and the root portion 47 thereof. The elastic force of the second coil spring 60 is made stronger than that of the first coil spring 54 provided between the thread tension disc 52 and the thread tension nut 49. As shown in FIG. 1, the root portion 47 is locked to the lower end portion 64 of the elongated hole 62 formed in the tubular body 58 by the set screw 70 against the elastic force of the second coil spring 60.
Therefore, the operating rod 46 can be raised and lowered together with the root portion 47 within the range of the length of the elongated hole 62. An eccentric outer ring 72 of an eccentric cam 71 mounted on the sewing machine upper shaft 50 is provided below the root portion 47 of the operating rod 46 so as to be freely contactable with the lower end of the root portion 47 of the operating rod 46 in response to the rotation of the upper shaft 50. . Reference numeral 73 is a hexagonal nut that can be screwed into the screw 57 of the tubular body 58, and is used to attach the needle thread tension control device 44 according to the present invention and the thread guide 41 from the bobbin to the sewing machine head 2 (FIG. 4). Reference numeral 41 is a thread guide for supplying the upper thread from the bobbin, and comprises a support plate 42 fitted in the tubular body 58, a hole 42a provided in the support plate 42, and a coil spring 43 extending from the support plate 42 in the thread winding direction. , The upper thread T passes through the coil spring 43 and the hole 42a, and is smoothly threaded on the thread tension discs 52, 52.
Supply to.

With the rotation of the upper shaft 50 of the sewing machine, the eccentric cam 71 is rotated so that the eccentric cam 71 can freely come into contact with the root portion 47 of the operating rod 46, and the operating rod 46 is moved up and down within the range of the elongated hole 62. . When the operating rod 46 is lifted by pushing up the eccentric outer ring 72 of the eccentric cam 71, the second coil spring 60 wound around the operating rod 46 housed in the tubular body 58 is compressed in the tubular body 58. At the same time, the first coil spring 54 wound around the outer circumference of the operating rod 46 between the thread tension nuts 48, 49 attached to the head of the operating rod 46 and the thread tension discs 52, 52 is the second coil spring 60. On the contrary, since the compression is released and the length of the first coil spring 54 is extended, the elastic force for pressing the thread tension discs 52, 52 is weakened, and therefore the pressing force between the thread tension discs 52, 52 is reduced, The sewing thread T passing between the thread tension discs 52, 52 can be smoothly fed out. Therefore, in the present invention, when the upper shaft 50 of the sewing machine is rotated, the lowest position of the eccentric outer ring 72 of the eccentric cam 71 in contact with the root portion 47 of the operating rod 46 and the balance 2
The top dead center of 4 is matched. Therefore, the upper thread T is smoothly fed out from the thread tension discs 52, 52 when the upper thread T moves downward from the top dead center of the balance 24. As described above, the eccentric cam 71 is mounted on the upper shaft 50, and the eccentric outer ring 72 of the eccentric cam 71 is the operating rod 4
It is possible to abut the end of the root portion 47 of No. 6. The eccentric cam 7
The contact state of the eccentric outer ring 72 with the root portion 47 of the operating rod 46 is performed in synchronism with the movements of the balance 24 and the needle bar 30, and the operation of the balance 24 and the needle bar 30 forms a smooth seam. It is possible to supply the needle thread having the tension required for the above.

Further, since the needle thread adjusting device of the conventional example performs lubrication and the like for smooth operation, there is a possibility that parts may be contaminated. However, the needle thread tension control device according to the present invention is designed for smooth operation. No need to lubricate. The reason is that the elastic forces of the first coil spring 54 and the second coil spring 60 are made different from each other to adjust the thread slippage of the sewing thread T from the thread tension disc 52. The needle thread tension control device 44 described above is shown in FIG.
It can be stored in the sewing machine head 2 except for a part as shown in FIG. Further, a simple thread guide 11 is simply provided at the position of the needle thread adjusting device 12 of the conventional example. The needle thread tension control device 44 configured as described above is mounted on the upper shaft 50 between the bearing metal 88 and the rotation balance 102, as shown in FIG. With reference to FIG. 3, members related to the upper shaft 50 of a commonly used link balance type sewing machine will be outlined. One end of the upper shaft 50 is rotatably supported in the head machine frame 2 through a bearing metal 88, and a balance balance 90 fixed to the upper shaft 50 has a support pin 9 fixed to the machine frame.
A crank pin 9 that rotatably supports the other end of the balance 24 rotatably attached to the second end and one end of the needle bar crank 94.
6, the needle 32 is fixed to the lower end of the needle bar 30, and the needle 32 is slidably fitted into the head machine frame 2 through a metal 98 provided on the upper portion thereof. Further, a needle bar tray 100 provided at a substantially middle portion of the needle bar 30 is rotatably engaged with the other end of the needle bar crank 94. The upper shaft 50 is provided with a rotation balance 102 and the above-mentioned balance wheel 38.

Next, a method for setting the needle thread tension of the needle thread tension control device of this embodiment will be described. When the operating balance 24 gradually rises due to the formation of the seam and reaches the top dead center, the eccentric outer ring 72 of the eccentric cam 71 attached to the upper shaft 50 also moves to the highest raised position as the upper shaft 50 rotates. As described above, the position of the eccentric outer ring 72 of the eccentric cam 71 is set in advance.
That is, when both members are in the above positions, the thread tension disc 5
The elastic force of the first coil spring 54 pressing the second and the second springs 52 becomes weaker than that of the second coil spring 60, and the upper thread T easily pulled out from the thread tension tray 52 as the balance 24 descends. , The needle hole 3 of the needle 32 through the thread guide group
An appropriate tension is applied between the screw 6 and the hole 13 of the balance 24 and the pair of thread tension discs 52 of the needle thread tension control device 44. Next, from this state, the balance 24 and the needle 32 descend and the needle 32
When the needle 32 and the balance 24 start to move up while forming a seam in the fabric by intertwining the upper thread T attached to the sewing machine bed 39 with the lower thread T'provided under the sewing machine bed 39, the upper thread tension controller 44 The eccentric outer ring 72 of the eccentric cam 71 also sequentially rises from the lowered position, and the actuating rod 46 contacting the outer periphery of the eccentric cam 71 rises along with the root portion 47 accordingly. When the upper shaft 50 further rotates and the eccentric cam 71 rolls to the raised position, the eccentric outer ring 72 of the eccentric cam 71 pushes up the actuation rod 46, so that the second coil spring 60 is compressed and the elastic force of the first coil spring 54 becomes weak. Nari, thread tension plate 52,
It becomes easy for the upper thread T from 52 to come off. In this way, since the contact degree of the pair of thread tension discs 52 changes in synchronization with the movement of the balance 24, the withdrawal of the upper thread T and the adjustment of the tension can be carried out very easily, and the balance 24 which is the related member, If the tuned position of the eccentric cam 71 is set in advance, the thread tension of the needle thread T can be automatically set. At the same time, the upper thread T required for forming the stitch is automatically supplied. Of course, it is necessary to regulate the contact degree of the thread tension disc 52 in advance together with the arrangement state of the balance 24 and the eccentric cam 71. In this case, the thread tension nuts 48 and 49 are operated. In the above embodiment, the upper shaft 50 of the sewing machine
The above-mentioned configuration is attached to a shaft provided in parallel with the upper shaft 50, which is different from the upper shaft 50, and the shaft is connected to the upper shaft 50 of the sewing machine using a belt or the like. It can also be used as one independent accessory. It can also be used in high-speed sewing machines to improve work efficiency. In this embodiment, the lockstitch sewing machine has been described, but sewing machines other than the lockstitch sewing machine, for example, a rake stitch sewing machine, an overlock sewing machine, an embroidery sewing machine,
It can also be used for zigzag sewing machines and household sewing machines.

[0012]

[Effect] In the present invention, since the lowest descent position of the eccentric outer ring of the eccentric cam rotatably fixed to the upper shaft and the top dead center of the balance are made to coincide with each other, the upper thread tension of the upper thread is at the top dead center of the balance. Withdrawing from the control device becomes easy, and due to the displacement of the eccentric outer ring of the eccentric cam, the upper thread and the lower thread are appropriately adjusted by adjusting the eccentric outer ring displacement of the eccentric cam. In addition to the effect that it is possible to easily and accurately form a seam on a fabric by entanglement, fine adjustment of a needle thread adjusting device having a complicated structure including a thread take-up spring and the like as in the conventional example is unnecessary, and further the seam is formed. This has the effect of supplying the necessary amount of upper thread. It also has the effect that it can be detachably attached to the sewing machine head and used as an accessory. Further, the device of the present invention can be widely used for sewing machines other than lock stitch. Further, the yarn can be smoothly supplied from the bobbin to the yarn tension tray by the yarn guide.

[Brief description of drawings]

FIG. 1 is a plan view of a needle thread tension control device according to the present invention.

FIG. 2 is a sectional view of FIG.

FIG. 3 is a perspective view of the sewing machine showing the mounting position of the needle thread tension control device according to the present invention.

FIG. 4 is a perspective view of a sewing machine equipped with a needle thread tension control device according to the present invention.

FIG. 5 is a perspective view showing threading of a conventional upper thread.

FIG. 6 is an exploded side view of a conventional needle thread adjusting device.

FIG. 7 is a perspective view of a lower thread hook.

[Explanation of symbols]

 24 Balance 41 Thread Guide 42 Support Plate 42a Hole 43 Coil Spring 44 Upper Thread Tension Control Device 46 Actuator Rod 47 Root 48, 49 Thread Tension Nut 50 Sewing Machine Upper Spindle 52 Thread Tension Disc 54 First Coil Spring 56 Crown Head 58 Cylindrical Body 60 Second coil spring 62 Long hole 71 Eccentric cam 72 Eccentric outer ring

Claims (3)

[Claims] 1. An operating rod having a root portion capable of contacting an eccentric outer ring of an eccentric cam provided on the upper shaft of a sewing machine is vertically movably arranged in a cylindrical body, and is interposed between a thread tension nut and a thread tension disc. The first coil spring is wound around the outer circumference of the operating rod, and the second coil spring is wound around the outer circumference of the operating rod between the crown-shaped head of the tubular body and the root of the operating rod. A needle thread tension control device for a sewing machine that can be raised and lowered within the range of a long hole formed in the body. 2. A needle thread tension control device for a sewing machine according to claim 1, wherein the uppermost dead center of the eccentric outer ring of the eccentric cam and the top dead center of the balance coincide when the upper shaft of the sewing machine rotates. 3. The upper thread tension of a sewing machine according to claim 1 or 2, further comprising a thread guide for feeding the upper thread from the bobbin to a thread tension tray through a coil spring and a support plate fitted in a tubular body. Control device.