JPH08215467A - Thread cutting device for sewing machine - Google Patents

Abstract

PURPOSE: To prevent the end section of a cut thread from being inadvertently released by the action of a thread capturing plate. CONSTITUTION: This thread cutting device for a sewing machine is provided with a reciprocatable thread capturing plate 12 capturing a thread, a fixed edge 11 cutting the thread captured by the thread capturing plate 12 with an edge section 11a provided at the cutting position facing one face 12a of the thread capturing plate 12, and holding plates 13, 14 holding the vicinity of the cut end section of the sewing thread connected to a sewing needle. The holding members 13, 14 are constituted of the first holding plate 13 provided to face the other face of the thread capturing plate 12 and the flexible second holding plate 14 pressed into contact with the face of the first holding plate 13 not facing a moving edge. The pressure contact section between both holding plates 13, 14 is set at the front in the forward direction of the thread capturing plate 12 so that the thread captured by the thread capturing plate 12 in a thread shift passage enters between both holding plates 13, 14 before it reaches the cutting position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting device for a sewing machine, in which a thread connecting a sewing needle to a cloth is caught by a reciprocating thread catching plate and then cut with a fixed blade.

[0002]

2. Description of the Related Art At present, as a thread cutting device provided in a sewing machine, for example, one shown in FIG. 5 is generally known. The thread cutting device shown here is attached below the needle plate and cuts the thread from the sewing needle to the cloth. That is, 1 is a fixed blade fixed below the needle plate, and a blade portion 1a is formed at the tip thereof, and the blade portion 1a is a position retracted laterally from a needle drop position (not shown). Is set to.

Reference numeral 2 is a movable blade which horizontally reciprocates by a driving means (not shown), and a hook-shaped yarn catching portion 2a is formed at the tip thereof. Further, 3 is a thread holding plate provided below the movable blade 2. The thread holding plate 3 is composed of a flexible member, one end of which is fixed to the thread cutting base Ma with a screw B, and the other end of which is a cantilever spring which is constantly in pressure contact with the lower surface of the movable blade 2. Has become.

The conventional thread cutting device is constructed as described above, and the thread catching portion 2a of the movable blade 2 is located behind the blade portion 1a of the fixed blade 1 in the initial state before the thread cutting operation. . Here, when a thread cutting command is input to the control device of the sewing machine when the sewing operation is stopped or the like, the control device operates the drive means to move the movable blade 2 between the needle plate (not shown) and the sewing machine hook. Move it back and forth horizontally. At this time, the thread I1 from the sewing needle to the cloth is in a state of being hung from the needle plate to the sewing machine hook, and the movable blade 2 catches the thread by the catching section 2a, and between the fixed blade 1 and the movable blade 2. Disconnect.

The yarn I1 captured by the movable blade 2
Immediately before being cut, it penetrates between the lower surface of the movable blade 2 and the thread holding plate 3. Therefore, even after the thread cutting operation is completed, the end portion of the thread continuing to the sewing needle is moved to the movable blade 2 as shown in FIG.
And the yarn holding plate 3 continues to be held. The thread held here is naturally released by the movement of the cloth in the next sewing operation.

[0006]

As described above, in the conventional thread cutting device of the sewing machine, after the cutting operation is completed, the cut end portion of the thread I1 which is continuous with the needle is held until the next sewing operation is started. Therefore, there is an advantage that the needle thread loop can be accurately formed at the start of the sewing operation, and the stitch can be reliably formed from the first stitch.

However, since the lower thread is held between the lower surface of the movable blade and the thread holding plate, the movable blade 2 is erroneously operated after the thread is cut, or the movable needle 2 has a one-needle stopping function.
When the present invention is applied to a main needle sewing machine, the thread held by the movement of the movable blade is released, and the inconvenience that a stitch is not formed at the next few stitches at the start of sewing occurs.

For example, the present two-needle sewing machine with a one-needle stopping function has the above-mentioned disadvantages. That is,
In a sewing operation for changing from a double stitch to a single stitch as shown in FIG. 6, first, two stitches S1 and S2 formed by raising and lowering two stitch needles are formed, When the stitch reaches P1, the first thread cutting operation is first performed.
Next, one sewing needle is stopped upward, and the stitch S1q is formed only by the other sewing needle, and after reaching P2, the second sewing needle is formed.
Perform the second thread trimming operation. After that, a procedure is performed in which the two sewing needles are operated again in the next sewing product to form two stitches S1 and S2. Therefore, the thread for forming the stitch S2 held in the first cutting is released by the movement of the movable blade in the second cutting, and the stitch is formed for several stitches in the next sewing operation. There is an inconvenience that it is not performed (S0).

The present invention has been made in order to solve the above-mentioned inconveniences occurring in the prior art, and prevents the held yarn from being inadvertently released by the operation of the yarn catching plate or the like. An object is to provide a thread cutting device for a sewing machine to be obtained.

[0010]

A thread cutting device for a sewing machine according to the present invention is capable of reciprocating a thread catching plate for catching a thread extending from a sewing needle to a cloth in a bent state, and catching the thread catching plate on the thread catching plate. Holds a fixed blade that cuts the part of the thread that is threaded from the cloth to the thread catching plate with a blade part that is set at a cutting position that faces one surface of the thread catching plate, and the cut end of the sewing thread that is connected to the sewing needle. And a holding member for pressing the holding member to a non-opposing surface of the first holding plate provided to face the other surface of the yarn catching plate and the yarn catching plate of the first holding plate. And a flexible second holding plate having a pressure contact portion, and the pressure contact portion is set forward of the cutting position in the forward direction of the yarn catching plate, and the yarn moving path of the yarn catching plate is used. Before the captured thread reaches the cutting position, the captured thread is inserted between the two holding plates. In which was to so that.

[0011]

In the thread cutting device for a sewing machine according to the present invention, the thread catching plate reciprocates to catch the thread to be cut in a bent state, and the captured thread is fixed blade located at the cutting portion. The cutting end of the thread continuing to the sewing needle is introduced and held between the first holding plate and the second holding plate, and the thread is then cut. Even if the catching plate operates, the cut end of the thread is not inadvertently released accordingly, and when the sewing operation is started, the stitch can be reliably formed from the first stitch. .

[0012]

Embodiments of the present invention will be described below. 1 to 4 are views showing a first embodiment of the present invention. In the figure, 11 is a fixed blade whose rear end is fixed by a screw B to a thread cutting base Ma provided on the sewing machine frame. The fixed blade 11 has a blade portion 11a formed at the tip thereof, and the blade portion 11a is arranged at a predetermined cutting position set to the side of a needle drop hole (not shown) in the needle plate. Reference numeral 12 denotes a movable blade that is horizontally reciprocally movable by a driving means (not shown), and the blade portion 11 of the fixed blade 11 is constantly in pressure contact with one surface (upper surface) thereof. Further, the movable blade 12 has a hook-shaped yarn catching portion 12h and a blade portion 12e at the tip thereof, and the yarn caught by the yarn catching portion 12h is sheared between the blade portion 12e and the blade portion 11a. I'm supposed to get it. Further, the other surface (lower surface) 12b of the movable blade 12
A groove portion 12g extending along the reciprocating movement direction of the movable blade 12 is formed in this.

Reference numeral 13 denotes an upper holding plate (first holding member) whose rear end is fixed to the thread cutting base by a screw B, which is located on the lower surface side of the movable blade 12 and has a tip 13 thereof.
a is fitted in the groove portion 12g. The upper holding plate 13 is made of a flexible member, and the groove portion 1
The bottom surface 12g1 of 2g is movably pressed. Reference numeral 14 denotes a lower holding plate whose rear end is fixed together with the upper holding plate 13 by the screw B, and the pressure contact portion 1 is provided at the tip thereof.
2a is formed. The pressure contact portion 12a is in pressure contact with the lower surface of the tip portion 13a of the upper holding plate 13, and its tip portion is at the cutting position (setting position of the blade portion 11a of the fixed blade 11).
The movable blade 13 projects further forward in the forward direction (X1 direction).

The upper holding plate 13 and the lower holding plate 1 are
A holding member is constituted by 4 and.

In the first embodiment constructed as described above, during the thread cutting operation, the movable blade 12 horizontally reciprocates in the same manner as in the conventional case, so that the thread continuing from the sewing needle to the cloth is sewn on the needle plate and the sewing machine hook. And the captured yarn is sheared between the blade portion 11a of the fixed blade 11 and the blade portion 12a of the movable blade 12.
In the reciprocating motion of the movable blade 12, the yarn captured by the movable blade 12 bends as shown in FIG.
As shown in (b), the groove 12g is crossed below. Then, when the movable blade 12 moves from this state in the backward movement direction (X2 direction) indicated by the arrow, the yarn I bends the lower holding plate 14 slightly downward, as shown in FIG. 2C. Is guided to the upper surface of the sheet and is finally fed and sandwiched between the holding plates 13 and 14 as shown in FIGS. 3 (a) and 3 (b).

At this time, the upper holding plate 13 is fitted in the groove 12g of the movable blade 12, and the lower surface thereof is the lower surface 1 of the movable blade 12.
Since it does not protrude from 2b, the yarn I guided by the lower holding plate 14 is not caught by the upper holding plate 13 and is smoothly guided to the upper holding plate 13.

After that, even if the thread catching plate 11 operates, the cut end of the thread I will not be inadvertently released along with it, and when the sewing operation is started, the first stitch is surely performed. A seam can be formed from. Therefore, if the thread trimming device shown in the first embodiment is used in a two-needle sewing machine, even when sewing as shown in FIG. 6 is performed,
The cut end of the thread forming the seam S1 is not released at P2, and the seam S1 can be properly formed at the start of sewing after P3.

In the above embodiment, the movable blade 11
Although the upper holding plate 13 is fitted into the groove 11g formed on the lower surface of the thread, the thread can be smoothly inserted between the two holding plates 13 and 14. The pressure contact force with 11, both holding plates 13,
14 If the device is set to a value larger than the pressure contact force between the two, or if a means such as forming a yarn introducing gap G at the joining end portion of both holding plates as shown in the second embodiment of FIG. Even if the plate (first holding plate) movable blade (thread catching plate) is joined so as to project from the lower surface of the upper holding plate (first holding plate), the yarn can be reliably guided between both holding members. Therefore, the same effect as that of the above-described embodiment can be expected.

[0019]

As described above, in the thread cutting device for a sewing machine according to the present invention, before the thread catching plate catches the thread and the fixed blade cuts the thread, the caught thread is held by the first and second holding members. Since it is held by the above, even if the yarn catching plate is operated after cutting, the cut end of the cut yarn is not released accordingly. Therefore, when the movable blade is continuously operated due to an operation error, or two thread trimming devices are arranged corresponding to each needle of the two-needle sewing machine, both thread trimming devices are provided with the same drive source. Even if they are operated simultaneously, the cut end of the thread is reliably held until the sewing operation is started, so that the effect that the stitch can be reliably formed from the first stitch is there.

[Brief description of drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention, (a)
Shows a side view, and (b) shows a sectional view taken along line ZZ of that shown in (a).

FIG. 2 is a perspective view showing a tip portion of a movable blade in the same embodiment, (b) is an enlarged perspective view of what is shown in (a) from the bottom side, and (c) is what is shown in (b). It is a partial side view.

3A and 3B are diagrams showing a thread holding state in the same embodiment, FIG. 3A is a side view showing a thread holding state in the same embodiment, and FIG. 3B is a sectional view taken along line YY of FIG. 3A. is there.

FIG. 4 is a side view showing a second embodiment of the present invention.

FIG. 5 is a view showing a thread cutting device of a conventional sewing machine,
(A) shows a plan view, (b) shows a state in which the yarn is captured by a movable blade, and (c) shows a state in which the yarn is held.

FIG. 6 is a plan view showing a state of sewing with a two-needle sewing machine.

[Explanation of symbols]

 Ma Thread cutting base (sewing machine main body) 12 Movable blade (thread catching plate) 12a Upper surface (one surface) 12b Lower surface (other surface) 12g Groove portion 11 Fixed blade 13 Upper holding plate (first holding plate) 14 Lower holding Plate (second holding plate)

Claims (2)

[Claims] 1. A thread catching plate that is reciprocally supported by a sewing machine body and catches a thread from a sewing needle to a cloth in a bent state at the time of returning, and a cloth of the thread caught by the thread catching board. From the thread catching plate to the thread catching plate with a fixed blade that is placed at a predetermined cutting position facing one surface of the thread catching plate, and a cutting end of the sewing thread that continues to the sewing needle. A holding member for holding the vicinity thereof, wherein the holding member is provided on a non-opposing surface of the first holding plate provided to face the other surface of the movable blade and a fixed blade of the first holding plate. It is configured by a second holding plate having pressure contact and having flexibility, and the pressure contact portion is set in front of the yarn cutting position in the forward direction of the yarn catching plate, and is caught by the yarn moving path yarn catching plate. The thread caught between the two holding plates before it reaches the cutting position. Thread cutting device of a sewing machine, characterized in that the so that. 2. The thread catching plate is provided with a groove portion on the surface facing the first holding plate so that the first holding plate is slidably fitted, and on the surface facing the first holding plate. The thread cutting device for a sewing machine according to claim 1, wherein the bending thread is guided between the first holding plate and the second holding plate.