JPH05177073A - Seam forming device for sewing machine - Google Patents

Abstract

PURPOSE:To provide a seam forming device forming a vacant ring into a soft chain after the sewing to a fabric is completed. CONSTITUTION:A fixed member 14 fixed to a vertically movable needle bar 4, a thread stopper 15 provided separatably from the fixed member 14, an exciting body exciting the thread stopper 15 to the fixed member 14 so that a needle thread 1 is pinched between the thread stopper 15 and the fixed member 14, and a coupling body 22 provided position adjustably on the drive scalpel arm 18 of a cutting device performing the circular arc motion and separating the thread stopper 15 from the fixed member 14 in contact with the thread stopper 15 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seam forming device for a sewing machine, and more particularly to a seam forming device for a sewing machine in which an empty ring formed even after finishing sewing on a cloth is a soft chain.

[0002]

2. Description of the Related Art In an overlock sewing machine which cuts a cloth and forms an overlock stitch on the edge of the cut cloth, as shown in FIG. The ring S is formed to a predetermined length and cut.

The empty ring S is wound around the seam of the cloth to be sewn next, thereby preventing the seam from fraying at the start of sewing.

Sa shown in FIG. 7 is a standard hollow ring, 1 is a needle thread, 2 is an upper looper thread, and 3 is a lower looper thread.
(Needle thread 1 is shown by a black line)

By the way, this standard empty ring Sa has the following problems. As shown in FIG. 7, the upper looper thread 2 and the lower looper thread 3 of the standard empty ring Sa are formed so as to intersect with each other in a wavy shape, whereas the needle thread 1 is short in a substantially straight state.

When the standard empty ring Sa is stretched in order to wind it in the seam at the beginning of sewing, the looper threads 2 and 3 are dislocated from the needle thread 1 and frayed.

Further, in this standard empty ring Sa, the upper and lower looper threads are not tense when the operator straightly squeezes them, and it is difficult to remove them from the claw portion provided on the needle plate of the sewing machine when the operator comes to the front side. However, the standard empty ring Sa has an indefinite shape in this claw portion, and a dango-like seam is formed at the next sewing start portion, which causes a problem that the quality of the sewn product is deteriorated.

In order to solve the above-mentioned inconvenience, Sb in FIG.
As shown in FIG. 2, there is proposed a device for forming empty loop stitches in which the needle thread 1 is corrugated like the upper looper thread 2 and the lower looper thread 3. (Needle thread 1 is shown by a black line)

Those skilled in the art call the seam Sb shown in FIG. 8 a soft chain. This soft chain Sb
According to the method, when stretching, each sewing thread 1, 2 and 3 is elongated so as to be in a substantially straight line state, can be easily removed from the claw portion, and can be properly wound into the stitch at the next sewing start portion. It will be possible.

FIGS. 9 and 10 are views showing devices proposed for forming the above-mentioned soft chain. These devices are disclosed in Japanese Examined Patent Publication No. 55-43798 and Japanese Unexamined Patent Publication No. 62-207491. Each is disclosed.

In FIG. 9 (a), 4 is a needle anchor base having a sewing needle N at its lower end, and the needle anchor base 4 is moved up and down by the drive of a sewing machine motor (not shown), so that the sewing needle N moves linearly. It's designed to be eggplant.

Numeral 6 is an operating arm, and although detailed description is omitted, the operating arm 6 is configured to make a vertical swing motion by a drive source (not shown). 5 is a needle thread pressing spring fixed to the needle anchor base 4 by a fixing member 5a.

On the other hand, a reference numeral 7 is a regulating body which is fixed to the operating arm 6 by a screw 7a and makes a rotational movement as the operating arm 6 swings. A bent portion 7b at the tip of the regulating body 7 is as shown in the figure. It is adapted to face the presser spring 5.

Next, the operation of the seam forming device having the above-described structure during sewing will be described with reference to FIG. 9 (b).

As shown in FIG. 9B, the presser spring 5 and the regulating body 7 are repeatedly contacted and separated during sewing,
The pinch and release of the needle thread 1 (not shown) located between them is repeated.

That is, when the needle anchor base 4 is located at the top dead center, a constant space is formed between it and the bent portion 7b of the regulating body 7, and the operating arm 6 rotates clockwise. When the bent portion 7b of the regulating body 7 approaches the presser spring 5 and the needle anchor base 4 reaches the bottom dead center, the bent portion 7b engages with the presser spring 5 and the needle thread is placed between them. The needle clamp 4 is clamped, and the clamp is continued until the needle clamp base 4 slightly rises from the bottom dead center, and then the needle clamp base 4 is lifted away to release the clamp.

As a result, the air loop S formed from the edge of the fabric
Can be the soft chain Sb shown in FIG.

In addition to the seam forming device shown in FIG. 9, a seam forming device shown in FIG. 10 has been proposed.

In FIG. 10, 13 is a fixing plate fixed to the needle bar of the sewing machine, and 11 is a support bar provided on this fixing plate 13.

Reference numeral 10 denotes a thread pressing plate slidably supported by a support rod 11. The thread pressing plate 10 is supported so as to face the fixed plate 13 and is made of a magnetic material. Further, 12 is a spring body for urging the thread pressing plate 10 toward the fixed plate 13.

On the other hand, M is a magnet, and this magnet M is fixed to the machine frame of the sewing machine. The stitch forming device configured as described above can bring the thread pressing plate 10 into and out of contact with the fixed plate 13 by the up-and-down drive of the needle bar and the magnetic force of the magnet M, and the needles located between them. The empty ring S can be made into the soft chain Sb by repeatedly pinching and releasing the thread 1.

[0022]

However, the above-mentioned conventional seam forming device shown in FIGS. 9 and 10 has the following problems.

As is well known, the sewing machine drives the sewing machine at a high speed of 8000 spm, but the presser spring 5 shown in FIG. 9 is used.
Does not endure the repeated bending at high speed, and causes a disadvantage that the bent portion 5c (see FIG. 9B) is broken during long-term use.

The regulating body 7 and the presser spring 5 which perform different movements (rotational movement and vertical movement) slide the needle thread 1 from the needle bottom dead center until the lower looper scoops the needle thread 1 and tension is applied. In addition, since it is pinched, the needle thread 1 may be damaged.

On the other hand, in the stitch forming device shown in FIG. 10, since the needle thread 1 is held between the fixed plate 13 and the thread pressing plate 10 facing the fixed plate 13, the needle thread 1 is not damaged, but the sewing machine has a high speed. During sewing, the thread pressing plate 10 driven by magnetic force cannot follow the needle bar, and the thread pressing plate 1
0 remains separated from the fixed plate 13, that is, the needle thread 1 is not clamped, and eye skipping easily occurs, and the shift chain Sb cannot be formed.

[0026]

A sewing machine for a sewing machine according to the present invention has been made to solve the above-mentioned conventional problems. The sewing machine for sewing machine has a lower end supported by a sewing needle and is moved up and down. A fixed member fixed to the needle bar forming the needle bar, a thread stopper provided so as to be movable in contact with and separated from the fixed member, and a thread to clamp the needle thread between the thread stopper and the fixed member. An urging body for urging the stopper body against the fixing member, and a member provided on the driving female arm of the cutting device for engaging the thread stopper body and separating the yarn stopper body from the fixing member against the urging body. The present invention aims to solve the above-mentioned conventional problems by providing a combined body, and the engaging body is provided on the driving female arm so as to be positionally adjustable.

[0027]

In the sewing machine forming device for a sewing machine according to the present invention, the thread stopper is fixed to the fixing member by bringing the cam surface of the engaging body, which is provided in the driving female arm and makes an arc motion, into contact with the thread stopper. Contact and separate, and the pinch and release of the needle thread located between them is repeated.

By changing the position of the engaging body provided on the driving female arm so as to be adjustable in position, the timing of pinching and releasing the needle thread can be adjusted.

[0029]

Embodiments of the present invention will be described with reference to the drawings. The same parts as those of the conventional one are designated by the same reference numerals, and duplicate description will be omitted.

1 to 4 are views showing an embodiment of a seam forming device for a sewing machine according to the present invention.

In FIG. 1, C is a seam forming device installed in an overlock sewing machine, and this seam forming device C holds a needle thread and holds the needle thread A and releases the needle thread A. And means B.

FIG. 2 (a) is an exploded perspective view showing the configuration of the sandwiching means A. In the figure, 19 is a needle bar holder installed on the needle bar 4 by a screw 19a, together with the needle bar 4 which moves up and down by the swing of the needle drive shaft via a main shaft, a crank, a rod and the like which are rotated by a drive source not shown It is designed to move up and down.

A fixing member 14 is fixed to the needle bar holder 19 by a step screw 20, and a thread stopper 15 is slidable on the shaft of the step screw 20 so as to come in contact with and separate from the fixing member 14. Is.

Reference numeral 21 is a spring body as a biasing body,
The spring body 21 has one end in contact with the head of the step screw 20 and the other end in contact with the thread stopper 15 to urge the thread stopper 15 against the fixing member 14.

FIG. 2 (b) is an exploded perspective view showing the configuration of the releasing means B. In the drawing, 26 is a drive unit of a cutting device provided in the overlock sewing machine, and 18 is a drive that makes an arc motion by swinging a knife drive shaft 18b that swings via a main shaft, a crank, another rod, etc. not shown. Female arm, 25 is a female support 25a fixed to the driving female arm 18.
The knife is fixed to the sewing machine and is located near the sewing needle N. (See Figure 1)

Reference numeral 22 denotes an engaging body fixed to a screw hole 18a formed in the driving female arm 18 by a screw 24a. As shown in the drawing, the engaging body 22 is a screw receiving hole extending in the lateral direction. It has a hole 23, and its position can be adjusted in the direction shown by the arrow X.

Reference numeral 8 is a balance, and the balance 8 is a drive female arm 18
And the engaging body 22 are fixed to the drive female arm 18 together with the engaging body 22 by screws 24a and 24b.

The engaging body 22 has a slightly curved cam surface 22a so that the cam surface 22a faces the contact portion 15a formed on the thread stopper 15 of the thread catching means A. Is becoming The cam surface 22a is designed so that the locking body 15 floats on average as much as needed at the required time. (See Figure 1)

Further, 30 is a U-shaped needle thread guide, 31,
32 are thread guide holes, which are formed in the plate and fixed to the frame of the sewing machine. Reference numeral 33 is a thread tension device which is attached to the arm of the sewing machine.

Therefore, the needle thread is wound from a thread winding device (not shown), the thread tension adjuster 33, the thread guide hole 31 on one side of the needle thread guide 30, the balance 8,
A needle thread movement path is formed through the other thread guide hole 31 of the needle thread guide 30, the thread guide hole 32, the fixing portion 14 and the thread stopper 15 and the needle hole of the sewing needle N.

When the overlock sewing machine is driven, the seam forming device having the above-described structure includes the needle bar 4 that moves up and down and the drive knife arm 18 that moves in an arc, as shown in FIG.
As shown in (a) and (b), the needle thread 1 located between the fixing member 14 and the thread stopper 15 by separating and contacting the contact portion 15a of the thread stopper 15 and the engaging body 22. You can repeat pinching and releasing.

That is, the operation of the stitch forming device when the sewing needle N descends to the needle bottom dead center and rises to the needle top dead center will be described with reference to FIGS. 4 (a) and 4 (b).

The sewing needle N is lowered from the needle top dead center of 0 degree to 75
The engaging body 2 is attached to the contact portion 15a of the thread stopper 15 from 90 degrees to 90 degrees.
The second cam surface 22a comes into contact with the fixing member 14 and the thread stopper 1
The needle thread 1 is sandwiched between the five.

Then, when the sewing needle N pierces the cloth and rises slightly above the needle bottom dead center of 180 degrees, a loop is formed in the needle thread 1 by the frictional force of the cloth and is scooped by the lower looper 34.

At this time, tension is applied to the needle thread 1 by the spring body 21 shown in FIG. 2 (a), so that the loop is stably scooped by the lower looper 34 and no skipping phenomenon occurs.

Further, the thread stopper 15 is continuously pressed by the spring body 21 up to 285 degrees and is in a sandwiched state. After that, the contact surface 15a of the thread stopper 15 is engaged with the cam surface 22a of the engaging body 22.
The needle thread 1 between the fixing member 14 and the thread stopper 15
Is released and the needle thread 1 is in a released state where tension is not applied to the needle thread 1 from 285 degrees to 0 degrees to 75 degrees to 90 degrees. In this way, pinching and releasing are repeated for each needle.

Therefore, the needle thread 1 is fed out by the balance 8 from 115 degrees to 180 degrees, but the needle thread 1 is sandwiched by the fixing member 14 and the thread stopper 15 in that section, so that it is not shown by the balance 8. A soft chain is formed without pulling up the needle thread 1 from the empty ring of the needle plate claw portion. In FIG. 4, numeral 35 is an upper looper.

The holding state of the needle thread 1 is as follows.
Also, since the needle thread 1 is sandwiched by the thread stopper 15 which faces the needle thread 1, the needle thread 1 is not damaged, and the sewing machine can be driven appropriately at high speed.

Further, since the position of the engaging body 22 of the releasing means B can be adjusted by the elongated hole 23, this engaging body 2
2 is changed slightly or fully to the left of the elongated hole 23 of FIG. 2B, and the needle thread 1 by the thread stopper 15 is changed.
It is possible to adjust and change the timing of pinching and releasing.

As a result, a thin thread or a thick thread can be used and the standard empty ring Sa can be used.

In this embodiment, the engaging member 22 is located on the back side (upper side in FIG. 3) of the thread stopper 15; however, as another embodiment, as shown in FIG. 22 is located on the front side of the thread stopper 15, and the engagement body 22 and the contact portion 15a act in the arrow direction from the pinched state (a) of the needle thread 1 to engage the needle thread 1 in the released state (b). The thread stopper 15 may be tilted by the united body 22, and the needle thread 1 may be positioned in the gap created by this tilt.

[0052]

As described above, in the stitch forming device for a sewing machine according to the present invention, the thread clamping means for clamping the needle thread is brought into the released state by the engaging body provided on the drive knife arm so that the position thereof can be adjusted. Since it is configured as described above, the inconvenience of damaging the needle thread with a simple structure does not occur, and the sewing machine can be appropriately driven and driven at high speed.

Then, it becomes possible to adjust the timing of pinching and releasing the needle thread according to various needle threads and standard empty loops.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of a seam forming device for a sewing machine according to the present invention.

2A and 2B are exploded perspective views showing a configuration of main parts of the stitch forming device shown in FIG. 1, FIG. 2A is an exploded perspective view of a thread holding means, and FIG. 2B is an exploded perspective view of a release means.

3A and 3B are plan views of the essential parts showing the operation of the seam forming device of the sewing machine shown in FIG. 1, in which FIG. 3A is an explanatory diagram showing a needle thread clamped state and FIG.

4A and 4B are explanatory views for explaining the operation of the stitch forming device when the sewing needle descends to the needle bottom dead center and rises to the needle top dead center.

FIG. 5 is a plan view of the essential parts showing the operation of another embodiment of the sewing machine for sewing machine according to the present invention, in which (a) is a pinched state of the needle thread and (b) is an explanation showing the released state of the needle thread. It is a figure.

FIG. 6 is an explanatory view showing a cloth and an empty ring formed at an end portion of the cloth.

FIG. 7 is an explanatory view showing a standard empty ring formed by an overlock sewing machine.

FIG. 8 is an explanatory diagram showing an empty ring of a soft chain.

9A and 9B are views showing a conventional seam forming device for forming an empty ring of a soft chain, wherein FIG. 9A is an external perspective view and FIG. 9B is an operation explanatory view.

FIG. 10 is an external perspective view showing another conventional seam forming device that forms an empty ring of a soft chain.

[Explanation of symbols]

 14 fixing member 15 thread stopper 21 urging body (spring body) 18 driving female arm 22 engaging body 22a cam surface

Claims (1)

[Claims] 1. An overlock sewing machine which is provided with a cutting device for cutting a fabric and cuts the fabric and forms an overlock stitch along the cutting edge thereof to form an empty ring of a soft chain from the end of the fabric. A stitch forming device for a sewing machine, comprising a fixing member that supports a sewing needle at its lower end and is fixed to a needle bar that moves up and down, and a thread stopper that is movable so as to come into contact with and separate from the fixing member. And a biasing body that biases the thread stopper with respect to the fixing member so as to sandwich the needle thread between the thread stopper and the fixing member, and a driving female arm of the cutting device. And an engaging body that abuts the cam surface and separates the thread stopper from the fixing member against the biasing body, and the engaging body is provided on the driving female arm so that the position of the engaging body can be adjusted to contact the fixing member. Sewing machine characterized by adjustable amount Stitch forming apparatus.