JP2586516Y2 - Rotary thread trimmer of sewing machine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a sewing machine which cuts an upper thread and a lower thread by cooperation of a bobbin member which reciprocates along an arc-shaped movement path below a needle plate and a thread trimmer. The present invention relates to a rotary thread cutting device.

[0002]

2. Description of the Related Art At present, this type of apparatus is known as shown in FIGS. In FIG. 7, 1 is a boring knife fixed to the boring base 2 and 3 is a thread trimming knife fixed to the thread cutting base 4. These knives 1 and 3 are set outside the peripheral surface of the sewing machine F. Independent operations are performed along the arcuate path.

That is, the boring base 2 is provided rotatably about the lower shaft 5, and the boring base 2 is fixed to one holder 5 b 1 fixed to a metal 5 a loosely fitted to the lower shaft 5. A counter arm 8 is connected via a connection link 6, and the counter arm 8 is fixed to a thread cutting shaft 7 rotatably supported in the sewing machine bed. Further, the thread cutting base 4 is rotatably mounted around the lower shaft 5, and the thread cutting base 4 is fixed to the other holder 5b2 fixed to the metal 5a loosely fitted to the lower shaft 5, and protrudes from the holder 5b2. The female arm 11 is connected to the forked portion of the female arm 11 via the provided pin 9, and the female arm 11 is fixed to the thread cutting shaft 10. The female shaft 10 is rotatably inserted into the outer periphery of the thread cutting shaft 7, and the two shafts 7, 10 constitute a double shaft. Therefore, each of the scalpels 1 and 3 independently performs a rotational motion according to the rotation of each axis.

The shafts 7 and 10 are driven by a driving mechanism 20 shown in FIG. The drive mechanism 20 includes a bobbin cam 12 fixed to the lower shaft of the sewing machine.
And a scalpel cam 13, while a threading drive arm 14 is supported by the thread cutting shaft 7, and a knife drive arm 15 is supported by the knife shaft 10, and the threading drive arm 14 is provided at the distal end thereof. Cam 12 through the roller 14a
The distal end of the female cam 13 can be connected to the female drive arm 15.

[0005] These drive arms 14 and 15 are operated when arms provided on an interlocking mechanism (not shown) are joined and separated by a not shown thread cutting start solenoid and a thread cutting cam. . That is, when a thread trimming command signal is input, the thread trimming solenoid is turned on in response to the thread trimming command signal, and both drive arms 14 and 15 move to the joint positions with the corresponding cams 12 and 13, respectively. It has become. When the thread cutting operation is completed and the thread cutting solenoid is turned off, the drive arms 14 and 15 are separated from the cams 12 and 13, respectively.

When the two drive arms 14 and 15 are connected to the respective cams 12 and 13 by the thread trimming command as described above,
Each of the cams 12 and 13 rotating together with the lower shaft 5 is
4 and 15 respectively, and both drive arms 14 and 15
At the same time, the thread cutting shaft 7 and the female shaft 10 rotate independently. Further, the bobbin arm 8 moves the bobbin knife 1 from the side of the sewing machine hook F via the connecting link 6 by the rotation of the thread cutting shaft 7, and when the blade portion 1a reaches directly below the needle drop hole, Stop.

On the other hand, when the knife shaft 10 rotates, the rotation is transmitted from the knife arm 11 to the thread cutting base 4 via the pin 9, and the blade 3a of the thread cutting knife 3 is moved to the other side of the sewing machine F ( The needle plate NB is moved from the right side (right side in the figure) to just below the needle drop hole NBa (see FIG. 9). Here, the operations of the counter knife 1 and the thread cutting knife 3 are performed at different timings depending on the shapes of the counter cam 12 and the knife cam 13. That is, at the time of the thread cutting operation, first, the section A of the bobbin cam 12 and the bobbin drive arm 14 are joined, whereby the bobbin knife 1 moves to the cutting position, during which the sewing thread from the needle plate NB to the sewing machine F (Upper thread I1 and lower thread I2)
Among them, the yarn to be cut is selected and captured.

After that, the bobbin driving arm 14 is connected to the bobbin cam 1
In this period, the bobbin driving arm 14 stops moving, and the bobbin scalpel 1 is in a state in which the bobbin scalpel 1 holds the captured yarn immediately below the needle drop hole NBa. In this way, when the bobbin knife 1 is stopped, the knife drive arm 15 is simultaneously slightly lifted and pressed by the end of the knife cam 13 to rotate.
Moves to the cutting position, and the blade portion 3a formed at the tip thereof
The thread captured directly below the needle drop hole NBa is sheared by the blade portion (eyeball portion) 1a of the counter knife 1.

As described above, according to the rotary thread cutting device, since the thread can be cut immediately below the needle drop hole NBa, the length of the remaining yarn can be considerably reduced as compared with other thread cutting devices. And can contribute to improving the commercial value of the product. For example, as compared with a so-called horizontal movement type thread cutter in which a thread is caught and pulled out by a horizontally moving boring knife and the thread is cut between a fixed knife set at a position lateral to the needle drop hole. If this is the case, the length of the remaining yarn formed continuously with the cloth is greatly shortened, which is useful.

[0010]

However, even with the above-mentioned conventional rotary thread cutting device, the remaining yarn cannot be shortened to such an extent that there is no problem in quality. For high-end products that are required, the remaining thread may be cut manually by hand.
There has not yet been any material that can sufficiently shorten the remaining yarn.

For example, in the above-described conventional rotary thread cutting device, no matter how the positions of the blade portions 1a and 3a of the boring knife 1 and the thread cutting knife 3 are set near the needle drop hole NBa at the time of cutting. Remaining thread length To
The minimum is the thickness t1 of the needle plate NB, the amount of protrusion t2 of the feed dog Mc from the upper surface of the needle plate NB, the thickness t3 of the thread cutting knife 3, and the blade of the thread cutting knife 3, as shown in FIG. 3a is the length obtained by adding the gap t0 in consideration of the variation in the amount of rise when the blade 3a of the counter knife 1 rides on the blade (eyeball) 1a.
The length To of the yarn is a length that is clearly visible in appearance, and when the remaining yarn having such a length is formed,
Since the commercial value of the product will be impaired, in the case of high-end products, after removing the cloth, the long remaining thread is often cut with scissors, which is a factor that reduces productivity. Had become.

The present invention has been made in view of the above-mentioned problems of the prior art, and has as its object to provide a rotary thread cutter of a sewing machine capable of minimizing the length of a remaining thread formed after cutting. And

[0013]

According to the present invention, a needle is provided so as to be able to reciprocate from one side of a sewing machine along an arc-shaped movement path set along the periphery of the sewing machine, and a needle is provided at the time of forward movement. A bobbin member for catching a lower thread and an upper thread that is passed over a needle drop hole formed in a plate to a sewing machine hook, and an arc-shaped movement path set apart from the movement path of the bobble member The needle thread is provided so that it can reciprocate from the other side of the sewing machine shuttle to the vicinity of the needle plate along the needle thread. A thread cutting knife that presses in the vicinity of the drop hole, a bobber driving means for reciprocating the bobbin member, and a threading knife driving means for reciprocating the thread bobbin; The cloth placed on the needle drop hole faces the inside of the needle drop hole. It is intended to forward the drawing member to flex.

[0014]

The bobbin member of the present invention catches the upper thread and the lower thread that have been passed from the needle plate to the sewing machine hook, and then moves further forward in the forward movement direction than the needle drop hole and continues to the cloth. The thread is pulled down to the needle plate, and the cloth placed above the needle drop hole is bent toward the inside of the needle drop hole. It comes into contact with the yarn in the vicinity and cuts only by pressure contact between the blade of the thread cutting knife and the yarn instead of the conventional shearing method. Therefore, the blade portion of the thread cutting knife can be formed so that the thread can be cut at a position as close as possible to the lower surface of the needle plate regardless of the boring member. Therefore, the length from the cloth to the cutting position, that is, the length of the remaining thread is the thickness of the member supporting the cloth, for example, the thickness obtained by adding the thickness of the needle plate and the amount of protrusion of the feed dog from the upper surface of the needle plate. Shorter than before, and significantly shorter than before.

[0015]

1 to 6 show an embodiment of the present invention.
It will be described based on. In addition, the same reference numerals are given to the same parts as those in the above-mentioned conventional technology, and the description thereof is omitted. In each figure, 21 is a boring member supported by a boring base 22. The boring member 21 has substantially the same shape as the boring knife 1 shown in the above-mentioned prior art except that the blade portion is not present. The boring base 22 for supporting the boring member 21 has a thread cutting shaft via a connecting link 6 and a boring arm 8 connected to one of the holders, similarly to the boring base 2 shown in the prior art. 7, the bobbin member 21 can be moved along an arcuate movement path set around the sewing machine F by the rotation of the thread cutting shaft 7.

A thread cutting knife 23 is supported by a knife base 24. The thread cutting knife 23 shown here is
The blade 23a formed at the tip is formed on the upper surface side, which is different from the conventional thread cutting knife in which the blade is formed on the lower surface side. The knife base 24 is fixed to the other holder, and is connected to the thread cutting shaft 7 via a pin 24 a protruding from the other holder and the knife arm 11. The thread cutting knife 23 can be reciprocated along an arcuate movement path set around the sewing machine F. And
The bobbin member 21 and the thread trimming knife 23 are configured to simultaneously rotate in opposite directions from one side and the other side of the sewing machine F toward the thread trimming position based on the thread trimming signal.

In this embodiment, the thread cutting knife 2 is used.
The movement path 3 is set such that the blade section 23a of the thread cutting knife 23 does not contact the bobble member 21 and takes a path as close as possible to the opening of the needle drop hole NBa of the needle plate NB. Have been. In other words, this movement path is a large-diameter arc path that is spaced outside the movement path of the bobbin member 21.

On the other hand, in this embodiment, a driving mechanism 30 for rotating the thread cutting shaft 7 is configured as shown in FIG. In other words, the drive mechanism 30 is the same as the female cam 13 and the counterbore cam 12 in the drive mechanism 20 of the prior art.
Although one thread trimming cam 31 is attached to the lower shaft 5 in contrast to the case of being constituted by two cams, and furthermore, it is constituted by the two drive arms of the knife drive arm 15 and the boring drive arm 14 in the prior art. On the other hand, only one thread cutting drive arm 32 is provided.

Therefore, the driving mechanism 30 in this embodiment is
In this case, the thread cutting drive arm 32 is a single-axis drive in which the thread cutting shaft 7 is rotated by contact with the thread cutting cam 31, whereby the counter arm 8 and the female arm 11 are simultaneously rotated by the same angle. It has become. The joining / separating operation between the thread cutting drive arm 32 and the thread cutting cam 31 is performed by a thread cutting solenoid or the like (not shown) as in the related art. The thread trimming cam 31, thread trimming drive arm 32, thread trimming shaft 7, and knife arm 11 constitute thread trimming knife driving means. The thread trimming cam 31, thread trimming drive arm 32, thread trimming shaft 7, The bobble arm 8 and the connecting link 6 constitute a bobble member driving means.

In this embodiment constructed as above, the stop of the sewing operation and the thread trimming operation are instructed by pedal operation or the like, and when the sewing needle reaches the bottom dead center, a thread trimming signal is generated at the same time. In the same manner as in the prior art, the thread cutting drive arm 32 is driven by an interlocking mechanism including a thread cutting solenoid.
Is joined to a section C which is a pause section of the thread cutting cam 31.
When the sewing machine hook F catches the upper thread loop and the upper thread loop is passed over the needle plate NB and the sewing machine shuttle F, the thread cutting drive arm 32 comes into contact with the thread cutting operation section A of the thread cutting cam 31. Then, the rotation operation is started, and the yarn cutting shaft 7 rotates with the rotation.

Here, the rotation of the thread cutting shaft 7 is controlled by the counter arm 8
And transmitted to the boring base 22 via the connecting link 6,
The boring member 21 moves from the side of the sewing machine F to the cutting position indicated by the dashed line in FIG. During this time, the hanging member 21 is moved from the needle plate NB to the sewing machine shuttle F.
The yarns I1 and I2 to be cut are selectively captured from the two upper yarns I1, needle yarns Ia and lower yarns I2 that have been wound between them, and when the yarns reach the cutting position, the yarns are placed on the needle plate NB. (See FIG. 5).

As a result, a strong tension is generated in the pulled out upper thread I1 and lower thread I2, and the cloth W held above the needle plate NB by the tension causes the needle drop hole as shown in FIG. It is drawn toward NBa and becomes bent. However, at this time, since the cloth W is supported above the needle plate NB by the feed dog Mc, the cloth W is not necessarily drawn into the needle drop hole NBa.
It will bend below the upper surface of c. In FIG. 5, t4 indicates the amount of deflection of the cloth.

On the other hand, simultaneously with the rotation of the bobbin member 21 in the direction of the arrow in FIG. 4, the thread cutting knife 23 moves the knife arm 11, the pin 24 a and the knife base 24 in conjunction with the rotation of the thread cutting shaft 7. By operation, it moves from the other side of the sewing machine shuttle F to the thread cutting position shown by the dashed line in FIG. 4, where the blade 23 a formed at the tip is captured by the bobbin member 21. It presses against the yarns I1 and I2 and cuts them.

At this time, as described above, the cloth W is in a state of being bent downward by the thread pulling-in operation of the bobbin member 21, and the blade portion 23a is located at the lower opening of the needle drop hole NBa. Since the position is set as close as possible, the length of the yarn from the cloth W to the blade portion 23a of the thread cutting knife 23, that is, the length of the remaining yarn formed on the cloth W is much more than in the conventional case. It will be shortened. That is, in the conventional thread cutting device, the length To of the remaining thread formed on the cloth W is To ≒ t1 + t2 + t3 + t0, whereas the length T of the remaining thread formed by the thread cutting device in this embodiment is , Becomes

That is, in the thread cutting device of this embodiment, the length To of the remaining yarn by the conventional thread cutting device is compared with To.
The amount of downward bending t4 of the cloth W is reduced by the amount t4, and the blade portion 23a of the thread cutting knife 23 is formed on the upper surface, so that the thickness t3 of the thread cutting knife 23 and the boring member 2 are provided.
In FIG. 1, the gap t0 due to the conventional variation due to the elimination of the blade portion (eyeball portion) is eliminated, and the length of the remaining yarn is greatly reduced. Therefore, according to this embodiment, the commercial value is not impaired by the remaining yarns, and it is not necessary to cut off the remaining yarns by hand or the like after taking out the cloth W, so that the productivity is greatly improved. .

In the above embodiment, the feed dog Mc
Has been described as an example of a sewing machine that transports the cloth W using
The present invention is also applicable to a sewing machine in which the cloth W is always transported in a state of being joined to the upper surface of the needle plate without using the feed dog. In this case, since the cloth placed on the needle plate NB is drawn into the needle drop hole NBa by the bobbin member 21, the remaining yarn is further shortened as compared with the case where the feed dog Mc is used. It will be.

[0027]

As described above, in the rotary thread cutting device according to the present invention, the bobbin member for catching the yarn moves the captured yarn forward in the forward movement direction from the needle drop hole formed in the needle plate. While pulling in, the cloth is bent toward the needle drop hole, while the blade portion of the thread trimming knife that moves along a movement path that is more outwardly separated than the movement path of the picking member has a needle plate attached to the yarn captured by the picking member. Since it is designed to be cut in contact with the vicinity, the remaining yarn formed continuously with the cloth after cutting is greatly shortened as compared with the related art. For this reason, even if the remaining yarn is not cut off manually or the like, the commercial value of the product is not impaired, and an improvement in productivity can be expected.

[Brief description of the drawings]

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

FIG. 2 is a rear view showing a driving means in the embodiment.

FIG. 3 is a perspective view of what is shown in FIG.

FIG. 4 is an enlarged explanatory front view of a main part showing positions of a bobbin member and a thread cutting knife at the time of thread cutting in the embodiment.

FIG. 5 is an enlarged front view of a main part showing a state in which the bobbin member has pulled out the yarn in the embodiment.

FIG. 6 is an enlarged front view of a main part showing a state where the thread is cut by a thread cutting knife in the embodiment.

FIG. 7 is a front view showing a conventional rotary thread cutting device.

FIG. 8 is a perspective view showing a driving mechanism of the one shown in FIG. 7;

FIG. 9 is a main part enlarged explanatory front view showing a state at the time of thread cutting by a conventional rotary thread cutting device.

[Explanation of symbols]

 F Sewing machine hook NB Needle plate NBa Needle drop hole 21 Pulling member I1 Upper thread I2 Lower thread 23 Thread cutting knife 23a Blade section 6 Connecting link 8 Counterboring arm 12 Counterboring cam 14 Counterboring drive arm 31 Thread trimmer cam 32 Thread trimmer drive arm 11 Female arm

Claims (1)

(57) [Scope of request for utility model registration] 1. A needle drop hole which is provided so as to be reciprocable along an arcuate movement path set along one side of the sewing machine from one side of the sewing machine, and which is formed in a needle plate during forward movement. A bobbin member for catching a lower thread and an upper thread that has been passed from the sewing machine to the sewing machine, and the other side of the sewing machine along an arc-shaped moving path set apart from the moving path of the bobbin member. A thread trimming knife that is reciprocally movable from one side to the vicinity of the needle plate, and in which the blade portion presses the upper thread and the lower thread passed through the needle drop hole to the sewing machine hook in the forward movement in the vicinity of the needle drop hole. A bobber driving means for driving the bobbin member, and a threading knife driving means for driving the thread trimming knife, wherein the bobble member driving means is a cloth placed on a needle drop hole. Move the bobbin member forward until it bends inward of the needle drop hole Rotary thread cutting apparatus of a sewing machine characterized by and.