JPH11156077A - Bobbin thread cutter for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily cut a bobbin thread fed out from a bobbin case to a prescribed length by providing a blade part on a side opposed to the bobbin thread ring catching body of a lid in a sewing machine having an aperture part formed in the main body, which is arranged with a bobbin thread ring catching body, opened and closed by a lid pivotally supported to the maim body. SOLUTION: A half-rotation type shuttle body 15 formed stitches in cooperation with a large shuttle 13, a shuttle body presser 14 and a needle is mounted inside of a free arm 12 constituting a part of the main body 11 of the sewing machine 11 and the aperture part 17 formed in front of the arm 12 is opened and closed by the lid 18. Then, a bobbin 26 on which the bobbin thread 25 is wound is mounted to the shuttle body 15 in the state of being freely attachable and detachable. In this case, the blade part 29 is fixed to the inner surface side of the lid 18, namely a side opposed to the shuttle body 15, by heat welding. Then, a feeding out amount from the bobbin 26 of this bobbin thread 25, namely a length between the tip part of the thread 25 and the bobbin 26, is adjusted by properly changing the position of the lid 18 and then the thread 25 is cut off by using the blade part 29 formed at the lid 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Generally, in a lockstitch sewing machine or a household sewing machine, a bobbin thread drawn out of a bobbin case is cut to a predetermined length prior to a sewing operation. What made this cutting work as easy as possible, for example,
It is disclosed in Japanese Patent Publication No. 56-20876.

[0003]

However, in this device, the lower thread is always cut to a fixed length. However, when this length is determined on the basis of sewing that performs normal sewing on a cloth having a normal thickness, there are the following problems.
In other words, when zigzag sewing a cloth of normal thickness,
Since the zigzag sewing requires a longer thread feeding amount than the straight stitching, the length between the end of the lower thread and the bobbin case is short, and there is a concern that the first stitch cannot be formed. Conversely, when straight sewing a thin cloth, thin sewing requires a shorter amount of lower thread to be paid out than thick sewing, so the length between the end of the lower thread and the bobbin case becomes longer. There is a problem that the end of the lower thread is stuck to the seam after sewing and the beauty is impaired.

[0004] Therefore, an object of the present invention is to provide a lower thread cutting device for a sewing machine free of such problems.

[0005]

According to a first aspect of the present invention, there is provided a bobbin having a thread catcher disposed in a main body and holding a lower thread. An opening formed in the main body, which passes when the case is inserted into and removed from the thread catcher, is opened and closed by a lid pivotally supported by the main body. A thread cutting device of a sewing machine is provided, wherein a blade portion is provided on a side opposed to a yarn loop capturing body.

[0006]

In the first technical means, the angle of the lid provided with the blade can be changed with respect to the main body, so that the length between the thread catcher and the blade can be freely set. Therefore, when the bobbin case is mounted on the yarn catcher, the yarn fed from the bobbin case can be cut to the length described above. Thus, if the length is appropriately set in accordance with the sewing conditions, an optimum amount of feeding of the lower thread can be obtained.

[0007]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 to 3, the sewing machine 10 includes a main body 11. Free arm 1 that forms part of body 11
A semi-rotating inner hook 15 which forms a seam in cooperation with the cauldron 13, the inner hook presser 14 and the needle 16 is mounted inside the inner hook 2.

An opening 17 is formed in front of the free arm 12. The opening 17 is opened and closed by a lid 18. That is, a pair of pins 19 (only one is shown) protruding from the lid 18 is rotatably supported by a groove 21 formed at the tip of a leaf spring 20 fixed inside the free arm 12. As described above, the cover 18 pivotally supported by the free arm 12 can change the distance between the free arm 12 and the half-turn intermediate hook 15 by changing the angle between the cover 18 and the free arm 12. .

A bobbin 26 around which a lower thread 25 for forming a seam is wound is removably mounted on the half-turn inner hook 15. The attachment / detachment of the bobbin 26 to / from the half-turn inner hook 15 is as follows.
This is performed through an opening 17 formed in front of the free arm 12. At the start of sewing, the lid 18 is opened.
Is open. If the angle between the lid 18 and the free arm 12 is changed, the distance between the lid 18 and the half-turn type shuttle 15 can be changed. , Ie, the length between the end of the lower thread 25 and the bobbin 26, the position of the cover 18 is appropriately changed, the cover 18 is stopped by hand at the position, and formed on the cover 18. What is necessary is just to cut the lower thread 25 using the bent blade part 29. In addition, the blade part 29 is a cover 1
8 is attached by heat welding to the inner surface side, that is, the side facing the half-rotation type inner shuttle 15.

Thus, the optimum length between the leading end of the lower thread 25 and the bobbin 26 can be easily set according to the sewing conditions (the type of sewing and the thickness of the cloth). The first seam cannot be formed because the length between the bobbin 26 and the bobbin 26 is too short, or it can be prevented from protruding from the cloth due to being too long.

[Brief description of the drawings]

FIG. 1 is a perspective view of a lower thread cutting device of a sewing machine according to an embodiment of the present invention.

FIG. 2 is a horizontal sectional view of the apparatus of FIG. 1;

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a plan view of a blade portion of the apparatus of FIG.

[Explanation of symbols]

 12: Main body 15: Half-turn type shuttle (thread wheel catcher) 17: Opening 18: Lid 29: Blade

Claims (1)

[Claims] 1. A bobbin catcher is provided in the body, and an opening formed in the main body through which a bobbin case holding a lower thread passes when the bobbin case is inserted into and removed from the bobbin catcher. A thread cutting device for a sewing machine, wherein a blade portion is provided on a side of the sewing machine that is opened and closed by a cover pivotally supported by the main body, the blade portion being provided on a side of the cover opposite to the thread catcher.