JP2584981Y2 - Sewing machine thread trimmer - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a thread cutter for a sewing machine in which a movable knife and a thread picking arm are reciprocated in opposite directions to cut a thread from a needle plate to a sewing machine in a bent state. It concerns the device.

[0002]

2. Description of the Related Art At present, thread trimming devices for sewing machines are roughly classified into those having a movable knife and a fixed knife, and those having only a movable knife. Among these, as a thread trimming device having a fixed knife and a movable knife, the movable knife reciprocates horizontally below the needle plate, captures and draws out the thread from the needle plate to the sewing machine hook, and moves between the fixed knife and the fixed knife. In general, this type of thread cutter can simplify the shape of the knife, but because the fixed knife is set at a position away from the needle drop path, a long thread is cut on the cloth. However, there is a problem that the quality of sewing products is impaired.

[0003] On the other hand, as a thread cutting device for cutting a thread using only a movable knife, for example, a rotary thread cutting device is known. In this device, a rotary thread cutting device is held at a side of a sewing machine hook. The movable knife is rotated along the arc-shaped path set around the sewing machine hook, and the thread is cut just below the needle plate.This has the advantage that the thread remaining on the cloth can be significantly reduced. Have.

FIGS. 4 to 7 are views showing this rotary thread cutting mechanism. In FIG. 4, reference numeral 1 denotes a needle plate mounted on a sewing machine bed. The needle plate 1 has a needle drop hole 1a through which a sewing needle N is inserted. Reference numeral 2 denotes a well-known sewing machine stored in a sewing machine bed, in which a bobbin bobbin (not shown) is stored via a bobbin case 3.

A movable knife 4 has an arc shape and has a blade 4a at one end as shown in FIG. Reference numeral 5 denotes a thread pulling arm 5 having an arc shape smaller in diameter than the movable knife 4, and the tip 5a has a shape as shown in FIG.
The movable knife 4 and the thread take-up arm 5 move around the sewing machine 2 along an arc-shaped path having a curvature different from each other, and during the sewing operation, as shown in FIG. It is held at an initial position set on both sides of the shuttle 2.

At the time of the thread cutting operation, the lower shaft 5 of the sewing machine is operated.
In conjunction with the rotation of, the thread pulling arm 5 rotates clockwise in the figure and the movable knife 4 rotates counterclockwise. Thereby, first, the thread take-up arm 5 removes only the upper thread I1 and the lower thread I3 connected to the cloth from the two upper threads and one lower thread I3 located between the sewing machine hook 2 and the needle plate 1. The blade portion 6a of the movable scalpel 4 comes into contact with the upper thread I1 and the lower thread I3 located between the needle plate 1 and the needle I1, and each of the threads I1 just below the needle drop hole. , I3.

As described above, in the rotary thread trimmer that cuts the yarn only with the movable knife 4, the yarn I1, I
3 by bending each thread I1, I3 to be cut
To the blade 6 of the movable knife 4 by the tension.
The thread is cut by increasing the pressure contact force between a and the thread.

[0008]

However, in order to obtain the tension required for cutting in the above-mentioned conventional thread cutting device, the bending angle of the lower thread I3 in the threading arm 5 must be adjusted as shown in FIG. It was necessary to draw out the yarn until it became an acute angle, and to sufficiently increase the frictional resistance between the yarn picking arm 5 and the yarns I1 and I3. For this reason, in this type of thread cutting device, although the length of the remaining thread connected to the end of the stitch can be shortened,
On the contrary, the length of the bobbin thread from the bobbin case 3 to the cut end is long, and in the next sewing operation, the long bobbin thread becomes entangled with the lower surface of the cloth in a bird's nest shape, or the lower surface of the cloth. And the quality of sewn products has been degraded.

This invention has been made in view of the above-mentioned conventional problems, and it is possible to shorten the length of the remaining thread connected to the end of the seam of the cloth, as well as the length of the thread connected to the start of the seam. It is an object of the present invention to provide a thread trimming device for a sewing machine, which can also optimize the sewing machine.

[0010]

In the present invention, a movable knife and a thread take-up arm arranged in accordance with both rules of the sewing machine are reciprocated in opposite directions, and the needle plate and the sewing machine are moved by the thread take-up arm. The upper thread and the lower thread located between them are captured and bent, and the thread cutting operation is performed by bringing the blade portion of the thread cutter into contact with the upper thread and the lower thread from the thread picking arm to the sewing machine hook. In the above-described rotary thread trimmer of the sewing machine, a groove is formed at the tip of the thread pulling arm so that the upper thread and the lower thread to be captured can enter, and at least one of the upper and lower sides of the thread pulling arm is always provided. A holding plate is provided for holding the upper thread and the lower thread pressed into contact with the surface and penetrating into the groove between the thread take-up arm.

[0011]

In this invention, the thread is bent at an acute angle because the thread-pulling arm allows the thread to penetrate into the groove formed at the tip of the thread, and then further penetrates and clamps the thread between the clamping plate. Even without this, a high frictional force is generated between the threading arm and the thread, and a large tension can be generated in the thread from the threading arm to the needle plate. For this reason, an appropriate thread cutting operation can be obtained, and the length of the thread from the cut end to the bobbin case or the like held in the sewing machine can be kept to a necessary minimum, and the sewing is performed next. It is possible to prevent a long thread from being left at the seam start end of the sewing product.

[0012]

1 to 4 show an embodiment of the present invention.
It will be described based on. The same or corresponding parts as those of the above-described embodiment are denoted by the same reference numerals, and the description thereof is omitted. As shown in the side view of FIG. 1, the thread trimmer according to this embodiment includes a thread pulling arm 5 in the conventional rotary thread trimmer.
Instead of this, a thread pulling arm 11 as shown in FIGS. 2 and 3 is provided.

As shown in the drawing, the thread pulling arm 11 has an L-shaped bent shape, and its rear end is attached to a fixed base 10 which rotates in conjunction with the lower shaft of the sewing machine at the time of thread trimming operation. I have. A groove 1 extending in the forward movement direction (the direction of arrow A) is formed at the tip end of the threading arm 11 as shown in FIG.
2 is formed, and at the tip of one side forming one side of the groove 12, a thread dividing inclined surface 1 that is inclined outwardly is formed.
1A is formed, and the other side of the groove 12 is formed with a thread introduction inclined portion 11B inclined inward. In addition, the width of the groove 12 is formed so as to allow a thread to be inserted.

Reference numeral 13 denotes a holding plate constituted by a flexible member. The rear end of the holding plate 13 is fixed to the upper surface of the rear end of the thread pulling arm 11.
It is pressed against the upper surface of the threading arm 11 to cover the latter half of the groove 12. In addition, other configurations including the movable knife 4 are the same as those of the above-described conventional technology, and the overlapping description will be omitted.

In this embodiment having the above configuration,
At the time of the thread trimming operation, the thread pulling arm 11
Rotates clockwise (forward direction A) and the movable knife 4 rotates counterclockwise (forward direction B). In the forward movement process, first, the thread take-up arm 11 first has two upper threads I existing between the sewing machine shuttle 2 and the needle plate 1 as shown in FIG.
The upper thread I2 connected to the sewing needle N is removed to the outside by the thread dividing inclined surface 11A from among the thread I, I2 and one lower thread I3, and the upper thread I is inserted into the groove by the thread introducing inclined surface.
1 and the lower thread I3 are introduced, and the upper threads I1 and I3, which have been introduced at a point slightly passing through the needle drop path, are caused to penetrate and clamp the clamping plate 13 (see FIG. 3B). The yarns I1 and I3 captured by rotating to the return start position shown in FIG.

By this bobbin operation, the length of the bobbin thread I1 from the bobbin case 3 to the needle plate 1 becomes the minimum length required for the next sewing operation. Is an obtuse angle as shown in FIG. Therefore, when the same amount of bobbin movement is performed in the conventional apparatus, the tip 5a of the bobbin arm 5 and the yarn I
1 and I3, the frictional resistance is extremely low. The thread I1 is unnecessarily fed out from the lower thread bobbin, and sufficient tension is applied to the threads I1 and I3 from the thread picking arm 5 to the needle plate 1. It cannot be generated.

However, in this embodiment, the yarns I1, I3
Is held between the holding plate 13 and the thread-pulling arm 11, so that the threads I 1 and I 3 from the thread-pulling arm 11 to the needle plate 1 have Large tension can be generated.

On the other hand, when the movable knife 4 has started the forward rotation in the counterclockwise direction, the blade formed at the tip of the movable knife 4 at the time when the threading arm 11 has reached the backward movement start position has the needle drop position. It reaches the cutting position immediately below and comes into contact with the upper threads I1 and I2 captured by the thread picking arm. At this time, since a large tension is generated in the yarns I1 and I3,
The blade portion 4a of the movable knife 4 can be brought into contact with a sufficient pressure contact force, and the yarns I1 and I3 can be reliably cut. Further, since the length of the bobbin thread I3 from the bobbin case 3 to the cut end is the minimum length required previously set, in the next sewing, a long bobbin thread I2 is formed at the start end of the seam of the cloth. Will not be left.

Therefore, according to this embodiment, a long remaining thread is not formed at both the start end and the rear end of the seam, and excellent quality can be obtained. After the thread cutting operation, the thread picking arm 11 moves the threads I1, I
3 is returned to the initial position with the yarn I1,
I3 is pulled up by the upper thread loop at the first needle after the start of the sewing operation, and is spontaneously withdrawn from both members 11, 13.

In the above-described embodiment, the holding plate 13 is fixed to the upper surface of the threading arm 11, but the holding plate 13 may be attached to the lower surface of the threading arm 11, and the shape thereof is particularly shown in the above embodiment. It is not limited to one. Further, in the above-described embodiment, the rotary type thread trimmer has been described as an example. However, the present invention is also applicable to a type in which the movable knife and the thread picking arm move horizontally, and the present invention is not particularly limited to the rotary type thread trimmer. .

[0021]

[Effects of the Invention] As described above, in the present invention, after a thread to be cut is bent by a threading arm to generate tension, the thread is cut by a movable knife immediately below a needle drop hole. In the thread trimmer of the sewing machine, a groove for introducing a thread to be cut is formed at the tip of the thread pulling arm, and a holding plate for holding the thread inserted in the groove between the thread pulling arm and the thread pulling arm is provided. In addition, it is possible to generate a sufficient yarn tension on the yarn with the minimum necessary amount of bobbin. For this reason, according to this thread cutting device, the length of the remaining thread connected to the seam end of the cloth can be shortened similarly to the conventional device, and the length of the remaining thread connected to the seam start end can also be optimized. Can greatly improve the quality of the sewn product.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of the present invention.

FIG. 2 is a plan view of a main part of what is shown in FIG.

FIG. 3 is a partially enlarged plan view of what is shown in FIG. 1,
(A) shows the state before the thread-drawing operation, and (b) shows the state at the time of the thread-drawing operation.

FIG. 4 is a side view showing an initial state in a conventional rotary thread cutting device.

FIG. 5 is a plan view showing the thread pulling arm and the distal end of the movable knife shown in FIG. 5;

FIG. 6 is a side view showing a state where the thread picking arm has captured the thread from the state shown in FIG. 5;

7 shows a state where the movable knife has come into contact with the thread from the state shown in FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Needle plate 2 Sewing machine hook 4 Movable knife 4a Blade 11 Threading arm 12 Groove 13 Clamping plate I1, I2 Upper thread I3 Lower thread

Continuation of the front page (56) References JP-A-58-105791 (JP, A) JP-A-2-213385 (JP, A) JP-A-3-10871 (JP, U) JP-A-2-63786 (JP) , U) Japanese Patent Publication No. 57-54158 (JP, B2) Japanese Patent Publication No. 47-17572 (JP, B1) Japanese Patent Publication No. 39-1129 (JP, B1) Japanese Utility Model Publication No. 2-14776 (JP, Y2) (58) Field surveyed (Int. Cl. ⁶ , DB name) D05B 65/02

Claims (1)

(57) [Scope of request for utility model registration] A movable knife reciprocating from a predetermined initial position separated from the needle drop path to a cutting position set near the needle drop path; and a predetermined thread catching position beyond the needle drop path from the initial position. A thread take-up arm that reciprocates over the sewing machine. By reciprocating the thread take-up arm and the movable knife in opposite directions, the upper thread and the lower thread located between the needle plate and the sewing machine can be threaded. A thread trimming device for a sewing machine, which bends with a bobbin arm, and performs a thread trimmer operation by bringing the movable knife into contact with an upper thread and a lower thread from a needle plate to a bobbin arm. A groove is formed at the tip to allow the upper and lower yarns to be captured to penetrate, and the upper and lower yarns which are always in pressure contact with one of the upper and lower surfaces of the yarn pulling arm to penetrate the groove. Provided a holding plate to hold between the arm Thread cutting device of a sewing machine characterized by and.