JPH05237284A - Bobbin thread supply device for sewing machine - Google Patents

Abstract

PURPOSE:To greatly extend the length of a bobbin thread which may be continuously fed, so as to remarkably enhance the efficiency of a sewing work, and to easily adjust the tension of the bobbin thread to be fed, irrespective of the diameter of the bobbin thread. CONSTITUTION:A bobbin thread spool for holding a bobbin thread T to be fed is provided on the outside of a bobbin case 13 which is stored in a rotating hook bobbin case holder 12. The bobbin thread T is led to an attaching shaft 22 from the bobbin thread spool 15 through a brake device 14 which incorporates clamping members 31, 34 so that the tension of the thread may be adjusted by means of butterfly nuts 34, 34, and is led into a bobbin case 13 from a slit 22a in the attaching shaft 22 through a slit 23a in a fitting shaft 23 of the bobbin case 13. Then, the thread is guided by a guide part 25 so as to be fed toward a fabric through a bobbin thread supply hole 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lower thread supplying device for a lower thread of a sewing machine.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional bobbin thread feeder 1 for a sewing machine.
Is shown. In this figure, the bobbin thread feeder 1 is
Located directly below the needle 3 at the tip of the arm 2 and built in the bed 4, an outer hook 5, an inner hook 6 accommodated in the outer hook 5, a bobbin case 7 accommodated in the inner hook 6,
The bobbin case 7 further comprises a bobbin (not shown) housed in the bobbin case 7.

A bobbin thread is wound around the bobbin, and a bobbin case 7 is provided with a bobbin thread supply hole (thread thread). The bobbin thread wound on the bobbin is sewn from the bobbin thread supply hole. Is supplied to the fabric side. A tension spring, such as a leaf spring, is provided in the bobbin thread supply hole to adjust the tension of the bobbin thread to be supplied so that proper stitches are formed on the cloth. In this way, the bobbin thread supplied from the bobbin case 7 is entangled with the needle thread sent to the lower side of the cloth together with the needle 3 by the shuttle hook 6, and the cloths are sequentially sewn together.

[0004]

However, in the bobbin thread feeder 1 having such a structure, the bobbin is accommodated in the bobbin case 7, and the bobbin case 7 is further accommodated in the inner hook 6. The size of the bobbin cannot be made larger than that of the bobbin case 7 or the inner hook 6. Therefore, the length of the bobbin thread that can be wound around the bobbin is naturally limited. Therefore, when a large amount of sewing is performed, bobbin thread breakage occurs many times during the sewing work,
The bobbin had to be replaced every time, resulting in a significant decrease in work efficiency.

Further, since the tension of the lower thread is adjusted by the tension springs provided in the bobbin case, for example, when the lower threads having different thicknesses are used, the tension of each of the tension springs is adjusted or each tension spring is adjusted. It was necessary to prepare in advance a plurality of bobbin cases whose tone springs were adjusted according to the thickness of the bobbin thread.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and a lower thread supply of a sewing machine for supplying a lower thread from a bobbin case mounted in the inner hook of a sewing machine. In the apparatus, the bobbin case is provided with a lower thread supply hole that communicates the inside and the outside of the bobbin case, and a guide portion that guides the lower thread fed into the bobbin case to the lower thread supply hole. At the same time, a bobbin winding wheel for holding the bobbin thread is provided outside the bobbin case, and the bobbin winding wheel and the bobbin case are opposed to each other so that the bobbin thread can be narrowed and the gap can be adjusted. A brake device having two narrowing members is provided.

[0007]

According to the bobbin thread supplying device having such a structure, the bobbin thread is supplied into the bobbin case from the bobbin thread winding wheel outside the bobbin case and guided by the guide portion provided in the bobbin case. It is sent out from the yarn supply hole. Therefore,
The size of the bobbin winder is not restricted by the size of the bobbin case, and the length of the bobbin thread that can be wound around the bobbin winder can be set to be significantly long. In addition, the tension of the lower thread supplied depends on the thickness of the lower thread,
This can be easily adjusted by adjusting the distance between the two narrowing members and applying an appropriate frictional force to the bobbin thread, and it is not necessary to replace the bobbin case each time depending on the thickness of the bobbin thread.

[0008]

FIG. 1 shows an embodiment of the present invention. In this figure, the bobbin thread supplying device includes an outer hook 11, a middle hook 12, and a bobbin case 13, which are built in a sewing machine bed immediately below a needle (not shown) at the end of an arm.
It is composed of a brake device 14 and a bobbin winder 15 which are housed at positions apart from them.

The outer hook 11 is attached to a support shaft 21 horizontally provided in the bed, and the inner hook 12 is housed in the outer hook 11 so as to be rotatable around the support shaft 21. There is. A hollow mounting shaft 22 is provided coaxially with the support shaft 21 in the center of the rotary hook 12, and a slit 22a is provided on the upper side surface of the tip of the mounting shaft 22.
Are formed.

On the other hand, the bobbin case 13 is a cylindrical member with a bottom, and a hollow fitting shaft 23 is provided at the center thereof, and the fitting shaft 23 is fitted onto the mounting shaft 22.
It is mounted inside the rotary hook 12 with its opening facing the support shaft 21 side. Further, a slit 23a is formed on one side of the fitting shaft 23, and the slit 23a overlaps with the slit 22a of the mounting shaft 22 when the bobbin case 13 is mounted, so that the hollow portion inside the mounting shaft 22 and the bobbin can be prevented. It is set so as to communicate with the inside of the case 13.
In addition, the bobbin case 13 has a side edge portion which faces the side where the slit 23a of the fitting shaft 23 is provided, toward the lower thread supply hole 2
4 are formed. The lower thread supply hole 24 is a through hole that allows the inside and the outside of the bobbin case 13 to communicate with each other, and the opening on the outside thereof is provided at a position that does not interfere with the rotating operation of the center hook 12. Further, in the bobbin case 13, a guide portion 25 is provided between the lower thread supply hole 24 and the slit 23a of the fitting shaft 23. The guide portion 25 is provided so as to project from the inner bottom surface of the bobbin case 13, and the tip end portion thereof is bent and formed in a hook shape.

On the other hand, the brake device 14 and the bobbin winder 15 are arranged at positions facing the rear end side opening of the mounting shaft 22. The brake device 14 is a plate-shaped lower narrowing member 31 that is horizontally supported in the bed, and has the same shape as the lower narrowing member 31 and is disposed so as to overlap the lower narrowing member 31. Narrowing member 32, two mounting bolts 33, 33 penetrating both ends of the lower narrowing member 31 and the upper narrowing member 32 in the thickness direction, and a butterfly screwed to these mounting bolts 33, 33. It is composed of nuts 34, 34. The lower narrowing member 31 and the upper narrowing member 32 have a longitudinal direction in which the lower thread T is fed (see FIG. 1).
In the right side to the left side). In addition, the bobbin winder 15 has the brake device 14
It is a bobbin-shaped member rotatably supported in the bed on the rear side of the bobbin, and bobbin thread T is wound and held in multiple layers on the body peripheral portion.

In the bobbin thread supplying device having such a structure, the bobbin thread T is fed from the bobbin winding wheel 15 and passes through between the lower narrowing member 31 and the upper narrowing member 32 of the brake device 14 to form a middle thread. It is inserted into the mounting shaft 22 of the rotary hook 12. Here, in the brake device 14, the tightening by the wing nuts 34, 34 is adjusted to adjust the lower narrowing member 31 and the upper narrowing member 32.
It is possible to adjust the distance between the
By adjusting this interval according to the thickness of the lower thread T, the frictional force acting on the fed lower thread T can be adjusted and the tension of the lower thread T can be adjusted. On the other hand, the bobbin thread T inserted through the mounting shaft 22 is fed into the bobbin case 13 through the slit 22a at the tip of the mounting shaft 22 and the slit 23a of the fitting shaft 23 of the bobbin case 13 that overlaps the slit 22a. Further, the lower thread T is hooked by the hook at the tip of the guide portion 25 and guided to the lower thread supply hole 24, is fed from the lower thread supply hole 24 to the outside of the bobbin case 13, and is fed to the fabric side. The bobbin thread T sent out in this manner is entwined with the needle thread sent to the lower side of the cloth together with the needle by the shuttle hook 12, and the cloth is sewn one after another.

As described above, in this embodiment, the bobbin case 1
3 does not hold the lower thread T but merely guides it, and the lower thread T is wound and held by a lower thread winding wheel 15 provided outside the bobbin case 13. Here, the bobbin winder 15
The size of the bobbin case 13 and the shuttle hook 12 does not depend on the size of the bobbin case 13 and the shuttle hook 12. Therefore, the length of the bobbin thread T that can be wound around the bobbin winding wheel 15 depends on the size of the bobbin case 13 and the shuttle hook 12. Since it is not restricted, the length of the lower thread T that can be continuously supplied can be greatly extended. Therefore, according to this embodiment, even when a large amount of sewing is performed,
Unlike the conventional case, the bobbin is not frequently broken and the bobbin is not necessarily replaced, and continuous sewing work for a long time can be performed, and work efficiency can be significantly improved.

Further, in this embodiment, the brake device 14 for adjusting the tension of the lower thread T to be fed is also arranged at a position distant from the bobbin case 13 and the wing nuts 34, 34.
Tension can be adjusted by tightening. As a result, it is not necessary to remove the bobbin case for adjustment or prepare a plurality of bobbin cases according to the thickness of the bobbin thread as in the conventional case. In contrast, the tension of the lower thread T can be adjusted very easily and with good workability, and proper stitches can be formed.

Although the bobbin winding wheel 15 is housed in the bed of the sewing machine in the above embodiment, it may be arranged outside the sewing machine. In this case, the size of the bobbin winding wheel 15 and the length of the bobbin thread T that can be wound are not restricted by the size of the sewing machine, and the length of the bobbin thread T that can be continuously supplied. Can be further extended. In order to prevent the slack in the lower thread T between the brake device 14 and the lower thread winding wheel 15,
It is desirable to apply a proper load to the rotation of No. 5 to give tension to the lower thread T. As a means of giving such a load,
For example, a means may be considered in which a spring plate or the like is directly brought into contact with the bobbin winding wheel 15 or a spring plate or the like is brought into contact with a shaft supporting the bobbin winding wheel 15.

[0016]

As described above, according to the present invention, the length of the continuously feedable bobbin thread can be greatly extended to significantly improve the sewing work efficiency and the bobbin thread can be fed. The tension of the lower thread can be adjusted extremely easily regardless of the thickness of the lower thread.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view of a bed of a sewing machine showing an embodiment of the present invention.

FIG. 2 is a partially transparent perspective view showing a lower thread supply device 1 of a conventional sewing machine.

[Explanation of symbols]

 11 Outer hook 12 Middle hook 13 Bobbin case 14 Brake device 15 Lower thread winding wheel 22 Mounting shaft 22a Slit 23 Fitting shaft 23a Slit 24 Lower thread supply hole 25 Guide part 31 Lower narrowing member 32 Upper narrowing member 33 Mounting bolt 34 Butterfly Nut T bobbin

Claims (1)

[Claims] 1. A bobbin thread supplying device for supplying a bobbin thread from a bobbin case mounted in the inner hook of a sewing machine, wherein the bobbin case has a bobbin thread communicating with the inside and outside of the bobbin case. A supply hole and a guide portion that guides the lower thread fed into the bobbin case to the lower thread supply hole are provided, and a bobbin winder that holds the lower thread is provided outside the bobbin case. A brake device is provided between the bobbin winder and the bobbin case. The brake device is provided with two narrowing members that can narrow the bobbin thread and that can adjust the gap. A bobbin thread supply device for a sewing machine.