JP2001162068A - Chain stitch sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chain stitch sewing machine capable of forming the final knot of chain stitches not frayed easily with a simpler structure. SOLUTION: This sewing machine forms chain knots in cooperation with a needle 6 and a rotary looper 41. The pressing force applied to a thread from a first stitch balancing thread tension 58 is adjusted by a solenoid 64 so that the first stitch balancing thread tension 58 is prevented from applying the pressing force to the thread by the solenoid 64 until a third thread loop 100c is pulled by a thread take-up lever 8 after the first thread loop is formed and the first stitch balancing thread tension 58 is allowed to apply the pressing force after the third thread loop 100c is pulled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chain stitch sewing machine for forming a chain stitch, and more particularly, to a chain stitch sewing machine for forming a knot which does not easily fray at the end of the chain stitch by electric control.

[0002]

2. Description of the Related Art Chain stitches are frayed one after another when the thread at the end of the seam is pulled. In order to prevent such fraying of the sewing thread, for example, Japanese Unexamined Patent Application Publication No. 9-290
As disclosed in Japanese Patent Publication No. 081, the chain stitch sewing machine for forming a knot by cooperation of a needle and a looper and a knot forming method are disclosed.

[0003] The above-described chain stitch sewing machine and the above-described knot forming method will be briefly described. From FIG. 21 (A) to FIG.
(C) shows the formation of the knot step by step in this order, and is a cross-sectional view of the cloth at the end of the seam. As shown in FIG. 21A to FIG.
Is a needle that moves up and down;
Reference numeral 503 denotes a thread catching portion that hangs the thread 507 by swinging, reference numeral 504 denotes a thread shift portion that pulls the thread by swinging, reference numeral 505 denotes a cloth, and reference numeral 506 denotes a thread.
Is a button.

FIG. 21A shows the sewing at the position where the needle 501 is most elevated after the last needle drop (meaning the needle drop just before the knot is formed and the thread is cut). FIG. Here, the looper 502 captures the thread 507 at the needle drop two times before the final needle drop, forming a first thread loop 507a. Then, FIG.
As shown in (B), the needle 501 is located on the needle drop position (another buttonhole) immediately before the final needle drop, and the portion of the thread forming the first thread loop 507a is threaded into the thread hooking portion 5.
03 captures. Next, as shown in FIG.
When the needle dropping just before the final needle dropping is performed, the looper 502 starts catching the thread hooked on the needle 501, and the thread shift section 504 starts the first thread loop 507a from below the thread hooking section 503. It is dragged toward one side of the thread hook 503, and the thread hook 503 holds the first thread loop 507a at a predetermined position. In this state, the portion of the yarn forming the first yarn loop 507a is folded back by the yarn hooking portion 503 and the yarn deviation portion 504, and the yarn is bent to form the first yarn loop 507a.

[0005] Next, as shown in FIG.
1 rises and the yarn deviation 504 moves away from the first yarn loop 507. At the same time, the yarn captured by the looper 502 is passed through the first yarn loop 507a to form a second yarn loop 507b, and the first yarn loop 507a is separated from the looper 502. In this state, the first yarn loop 5
07a and the second yarn loop 507b are
03 is hung. Thereafter, as shown in FIG. 22 (B), the final needle entry is made in the same buttonhole as the needle entry just before the final needle entry, and the second yarn loop 507b is pulled by one side by the yarn deviation portion 504. The looper 502 moves the needle 5
Start catching the thread 507 hanging on 01. In this state, the second yarn loop 507b is folded back by the yarn hooking portion 503 and the yarn deviation portion 504, and the yarn is bent to form the second yarn loop 507b. Then, FIG.
As shown in (C), the captured thread 507 is
2 passes through the second yarn loop 507b, and at the same time, the yarn deviation portion 504 separates from the second yarn loop 507b.

Then, as shown in FIG. 23A, the second thread loop 507b is released from the looper 502, and the second thread loop 507b is drawn to the cloth 505.
Before that, the first loop 50 hanging on the threading portion 503
7a and the second loop 507b are released. As a result, a third yarn loop 507c is formed, and the third yarn loop 507c passes through the second yarn loop 507b. Next, as shown in FIG. 23B, the needle 501 is further raised, and the third yarn loop 507c is further lowered. Then, as shown in FIG. 23 (C), the single yarn forming the first yarn loop 507a is held at a predetermined position in a hooked state to bend the yarn, and the second yarn loop 50
7b is bent back by the yarn hooking portion 503 and the yarn deviation portion 504, so that when the third yarn loop 507c is pulled, the third yarn loop 507c becomes the first yarn loop 507a.
And the first yarn loop 507a passes through the second yarn loop 507b. And the third thread loop 5
07c is lowered, and the third thread loop 507c is
08 and the fixed knife 509.

The knot formed as described above is shown in FIG.
As shown in (A), the knot formed by the first yarn loop 507a is a knot fastened by the knot formed by the second yarn loop 507b. FIG. 24 (A)
When the knot is loosened, the yarn end 507d comes off the first yarn loop 507a. In other words, the knot is formed by the part of the yarn 507 on the leading side of the part forming the first yarn loop 507a passing through the first yarn loop 507a with the cloth 505 sewn by one stitch, and Loop 50
7a passes through the second thread loop 507
b, and after straddling two of the yarns forming the first yarn loop 507a (that is, the second yarn loop 507b is fastened around the first yarn loop 507a), and then the first yarn loop 507a is fastened again. The knot passes through the yarn loop 507a. In this case, the portion of the yarn 507 at the tip of the first yarn loop 507a has passed through the first yarn loop 507a twice, and has passed around the first yarn loop 507a after passing through once. Since the first thread loop 507a has passed through the first thread loop 507a again from the same side as the first thread loop, even if the thread end 507d has once passed through the first thread loop 507a, the thread is still retained by the thread end 507a. The end 507d is still tied, and the knot is not completely frayed.

[0008]

By the way, in order to form the above-described knot, when the third yarn loop 507c is pulled through the second yarn loop 507b, the first yarn loop 507a becomes the third yarn loop 507a. It is necessary to be pulled to the base end side of the second yarn loop 507c, pass through the second yarn loop 507b, and surround the first yarn loop 507a with the second yarn loop 507b. When the yarn is not bent and the yarn is not loosened, the third yarn loop 507
c is pulled to pass through the second thread loop 507b even though the first thread loop 507a is pulled through the second thread loop 507b.
Can not pass. Therefore, in order to bend the yarn, the needle 501, the looper 502, the yarn hooking portion 503, and the yarn deviation portion 504
And the like are driven in cooperation, but the mechanism for driving these in cooperation has a complicated structure. In addition, since the needle 501, the looper 502, the thread hooking section 503, the thread shifting section 504, and the like are operated in a very narrow space, the structure for installing them is complicated.

Further, for example, if the thread hooking section 503 is omitted, the thread cannot be bent, and therefore, FIG.
As shown in (B), a knot is formed such that the first thread loop 507a does not pass through the second thread loop 507b, and a knot that is easily frayed is formed. The knot shown in FIG. 24B is a class symbol 101, 1 defined in JIS (Japanese Industrial Standard) -L-0120.
07, the yarn end 513 first passes through the second yarn loop 512 first, and the second yarn loop 51
2 has a problem that the knot easily comes off from the first thread loop 511 and the knot is easily frayed.

Further, even if an excessive amount of yarn is supplied to form a knot in order to bend the yarn, the knot itself becomes loose and the knot is easily frayed. there were.

The present invention has been made in view of the above circumstances, and can form a knot at the end of a chain stitch that is not easily frayed, and can form such a knot with a simpler configuration. An object of the present invention is to provide a chain stitch sewing machine.

[0012]

According to the first aspect of the present invention, there is provided a needle which moves up and down by inserting a thread,
A rotary looper that captures a thread from the needle and forms a thread loop by pulling the captured thread; and a thread tension device that sets a thread tension so as to adjust the deflection of the thread loop by electrical control. A chain stitch sewing machine that forms a chain stitch by cooperation of the needle and the rotary looper, wherein the thread tension device controls the rotary looper to remove at least one thread loop before a final needle drop. When forming, the thread tension is set so that the thread loop is bent, and when the rotary looper forms the thread loop of the final needle drop, the thread tension is set so that the thread loop is not bent. It is characterized by the following.

For example, in this chain stitch sewing machine, a thread guided from a thread tension device is inserted through a needle hole provided in a needle. Then, the needle descends, and the needle penetrates the sewing object and guides the thread under the sewing object. Then, a rotary looper captures the thread from the needle. Next, while the rotary looper rotates, the yarn is pulled to form a yarn loop, and the yarn is supplied from the yarn tension device. At this time, the bending of the yarn loop is adjusted by setting the yarn tension with the yarn tension device. And the needle goes up, then goes down again,
The thread is guided beneath the material to be sewn and the rotary looper recaptures the thread. Then, by pulling the yarn, a new yarn loop is formed, and this new yarn loop is passed through the previously formed yarn loop. By repeating these, a ring seam is formed.

As described above, according to the first aspect of the present invention, the yarn tension is set by the yarn tension device so that the yarn loop formed at least one before the final needle is bent. When the rotary looper pulls a thread loop formed by dropping (hereinafter referred to as a third thread loop), the third thread loop is set to set the thread tension so that the thread loop is not bent. Pulls a thread loop formed by the needle drop two times before the final needle drop (hereinafter, referred to as a first thread loop), and the pulled first thread loop is positioned just before the final needle. A formed yarn loop (hereinafter referred to as a second yarn loop)
Go through. This allows the first thread loop to form a knot fastened by the second thread loop.

Then, assuming that the third yarn loop is cut, the cut portion becomes the yarn end of the knot. When the knot is frayed, the yarn end is separated from the first yarn loop. Even if it comes off, the knot will not be completely frayed because the yarn end is still under the first yarn loop. Therefore, even if the knot formed as described above is pulled by rubbing the yarn end with the skin or the like,
It does not fray easily.

Further, when the third yarn loop is formed, the yarn tension device sets the yarn tension so that the yarn loop does not bend, so that excessive yarn is not supplied when forming the knot. Therefore, the knot itself becomes rigid, and the knot does not easily fray.

Further, since the yarn is not bent by the yarn hooking portion 503 as in the prior art, but the yarn is bent only by the yarn tension device, the knot can be formed with a very simple structure.
Further, since the yarn tension device adjusts the deflection of the yarn loop by electric control, the yarn tension device adjusts the deflection of the yarn loop by mechanical control.
Since 3) is reduced, the reliability is improved. Note that the state in which the thread loop is bent means that a thread (thread loop) serving as a chain stitch is not drawn to the sewing object and there is a gap between the sewing object and the thread. That is, a thread (thread loop) serving as a ring seam formed on the back side of the sewing object is loosened. That is, the ring seam is formed so as to be looser than the normal ring seam.

According to a second aspect of the present invention, in the chain stitch sewing machine according to the first aspect, the thread tension device includes a thread supply unit that supplies a thread to the needle, and a thread supply unit that supplies the thread to the needle. The thread tension that applies pressure to the thread on the path up to and the electrical control causes the rotary looper to bend when the rotary looper forms at least one thread loop before the final needle drop, and When the rotary looper forms the final needle drop yarn loop, the rotary looper includes pressure adjusting means for changing the pressure of the yarn tension so that the yarn loop does not bend. .

Here, the pressure adjusting means adjusts the pressure by the driving output of an electric driving means such as a solenoid or a motor. Also, by changing the pressure applied to the yarn from the yarn tension by the pressure adjusting means, the yarn tension can be set, and it is possible to adjust whether the yarn is pulled from the yarn loop or the yarn is supplied from the yarn supply unit. Can be. For example, if the pressure applied from the thread tension to the thread by the pressure adjusting means is substantially zero, the thread is pulled from the thread supply unit, the thread loop remains deflected, and the thread serving as the ring seam is sewn. I cannot be attracted to things. Further, even if the pressure applied to the thread from the thread tension by the pressure adjusting means is not substantially reduced to zero, the thread tension is reduced by applying a pressure lower than the pressure applied to the thread from the thread tension at the time of performing a normal chain stitch,
Form a bent yarn loop. That is, when the rotary looper forms the yarn loop at least one before the final needle drop, the yarn loop is deflected by applying pressure to the yarn from the yarn tension as described above. Further, if the pressure applied to the thread from the thread tension is extremely increased by the pressure adjusting means, the thread is pulled from the thread loop (ring stitch), the deflection of the thread loop is eliminated, and the thread is drawn to the sewing object. Can be That is, when the rotary looper forms the thread loop of the final needle drop, a stronger pressure is applied when the rotary looper forms the thread loop at least one before the final needle drop (when forming the normal loop seam). By applying a pressure higher than the pressure applied to the thread from the thread tension from the thread tension to the thread, the thread is strongly pulled from the thread loop (ring stitch) and the thread loop with the final needle drop does not bend. Become like The thread tension increases as the pressure applied to the yarn from the thread tension increases, and the thread tension decreases as the pressure applied to the yarn from the thread tension decreases.

As described above, according to the second aspect of the present invention, when the third thread loop is pulled so as to deflect the thread loop formed at least one before the final needle,
The third yarn loop pulls the first yarn loop to adjust the pressure applied from the yarn tension to the yarn by the pressure adjusting means so that the yarn loop does not bend. Passes through the second thread loop, so that the first thread loop can form a knot fastened by the second thread loop.

According to a third aspect of the present invention, in the chain stitch sewing machine according to the second aspect, the thread tension device applies pressure to a thread on a path from the thread supply unit to the thread tension. With the second thread tension, apply pressure to the thread only with the second thread tension from the first needle drop until the needle starts rising after the last needle drop, and then from the first needle drop to the last needle drop. After the needle loop starts to bend after the last needle drop, the pressure adjusting means increases the pressure applied to the yarn from the yarn tension by increasing the pressure applied to the yarn. A pressure is applied to the yarn from the thread tension and the second thread tension so that the final needle drop thread loop is not bent.

As described above, according to the third aspect of the present invention, the thread loop is in a bent state from the thread loop formed at the first needle drop to the formation of the second thread loop, and Since the third yarn loop is formed so as not to bend when the yarn is drawn, the third yarn loop pulls the first yarn loop, and the first yarn loop moves to the first yarn loop. It goes through the second thread loop. This allows the first thread loop to form a knot fastened by the second thread loop.

Further, since the third loop is formed so as not to bend when the thread is pulled, the knot itself becomes firm and the knot does not easily fray.

According to a fourth aspect of the present invention, in the chain stitch sewing machine according to the second aspect, the thread tension device applies pressure to a thread on a path from the thread supply unit to the thread tension. From the time when the needle first starts dropping until the needle drops just before the final needle drop, a pressure is applied to the thread from the thread tension and the second thread tension. Do not bend the thread loop formed two times before the final needle entry and before the final needle entry, and until the needle starts rising after the final needle entry The pressure adjusting means reduces the pressure applied to the yarn from the thread tension, deflects the yarn loop formed immediately before the final needle drop, and starts the needle rising after the final needle drop. Increasing the pressure applied by the pressure adjusting means to the yarn from the thread tension, and adjusting the thread tension and the second Added pressure from tension to the yarn, is characterized in that so as not to deflect the final stitch of the thread loop.

As described above, according to the fourth aspect of the present invention, from the time when the needle starts dropping just before the final needle drop to the time when the needle starts rising after the final needle drop, the pressure adjusting means moves from the thread tension to the thread. Since the applied pressure is reduced, the second yarn loop is formed in a bent state. And, since the third thread loop is formed so as not to bend when the thread is pulled, the third thread loop pulls the first thread loop, and the first thread loop becomes It goes through the second thread loop. This allows the first thread loop to form a knot fastened by the second thread loop.

Further, since the third loop is formed so as not to bend when the thread is pulled, the knot itself becomes rigid and the knot does not easily fray.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <First Embodiment> An embodiment of a chain stitch sewing machine according to the present invention will be described with reference to the drawings. The drawings are only schematically shown to the extent that the invention can be understood, and thus the invention is not limited to the illustrated examples.

FIG. 1 is a perspective view schematically showing a chain stitch sewing machine according to an embodiment of the present invention. FIG. 2 is a schematic perspective view showing an internal mechanism of the chain stitch sewing machine shown in FIG.
FIG. 3 is a schematic perspective view showing a main part of an internal mechanism of the sewing machine, and FIG. 4 is a plan view schematically showing an upper surface of a sewing machine arm of the sewing machine.

As shown in FIGS. 1 and 2, a chain stitch sewing machine 1
Is a bed portion 5 having a substantially horizontal bed surface, a vertical trunk portion 4 standing upright on a rear portion of the bed portion 5, and an upper portion of the vertical trunk portion 4 extending substantially parallel to the bed portion 5. A sewing machine frame 2 having a substantially U-shape as viewed from the side, comprising a sewing machine arm 3 extending forward.

Inside the vertical torso part 4, a presser lifting solenoid 1 is provided.
The plunger 12a, which is the output of the presser lifting solenoid 12, slides back and forth. A plunger 12a is connected to one end of a press-up link 13 extending forward and backward, and one end of a press-up lever 14 is rotatably connected to the other end of the press-up link 13. The presser lifting lever 14 has an intermediate portion rotatably supported with respect to the sewing machine frame 2, and a protrusion 14 a at the other end. Further, a tension spring 15 is connected to one end of the press-up lever 14, and the tension spring 15 urges one end of the press-up lever 14 to be pulled forward. A stopper 16 is provided in front of the presser lifting lever 14, and the stopper 16 prevents one end of the presser lifting lever from moving forward.

Further, a knob device 10 is provided on the bed portion 5, and the knob device 10 is rotatably supported at a rear end by a feed stand (not shown). A button clamp 17 is connected to a front end of the knob device 10. A compression spring 20 is connected to the knob device 10, and the knob device 10 is urged downward by the compression spring 20, and the urging force causes the button clamp 17 and the lower plate 11 connected to the feed table to be pressed. The cloth (sewn material) is clamped. In addition, the knob device 10
Has a hook portion 10a, and the hook portion 10a and the protruding portion 14a are engaged with play. And
The button clamp 17 is raised by the driving output of the presser lifting solenoid 12, and the cloth clamp by the button clamp 17 can be released.

One end of a thread cutting lever 18 is rotatably connected to an intermediate portion of the press-up link 13. The thread trimming lever 18 is rotatably supported by the sewing machine frame 2 at an intermediate portion. The thread cutting arm 19 extends vertically, and the upper end thereof is
Is rotatably supported. A cam groove 19a is provided at an intermediate portion of the thread cutting arm 19, and a cam roller (not shown) formed at the other end of the thread cutting lever 18 is engaged with the cam groove 19a. Further, one end of an L-shaped connecting plate 21 is rotatably connected to the other end of the thread cutting arm 19, and the other end of the connecting plate 21 has a thread cutting link 22 extending back and forth. One end is rotatably connected. As shown in FIG. 5, a moving knife 23 is rotatably connected to the other end of the thread cutting link 22. This moving knife 23
It is rotatably supported by a needle plate 24 (shown in FIG. 1) disposed below the lower plate 11, and the thread can be cut by a fixed knife 25 fixed to the needle plate 24. ing.

With the above-described configuration, when the presser lifting solenoid 12 is operated, the thread is cut by the moving knife 23 and the fixed knife 25, and the button clamp 17 clamps the button and the cloth in conjunction with the cutting of the thread. However, since there is play between the hook portion 10a and the protruding portion 14a, the release operation of the cloth clamp by the button clamp 17 is performed later than the yarn cutting operation. ing.

As shown in FIG. 3, a belt 26 is hung on a driving pulley of a sewing machine motor (not shown) and a driving pulley 27, and the rotational force of the sewing machine motor is
7 The drive pulley 27 is rotatably supported by a drive shaft 28 extending left and right, and the drive pulley 27 is fixed to the drive shaft 28 by operation of a blocking mechanism (not shown). To the drive shaft 28, a cutoff cam 29, an eccentric cam 30, and a helical gear 31 are fixed.

The blocking frame 32 is rotatably supported by the sewing machine frame 2, and a blocking hook 34 is provided on the front end of the blocking frame 32 via a cushion member 33.
Are provided movably back and forth. The front end 34a of the blocking hook 34 is locked to the cam portion 29a of the blocking cam 29. One end of a blocking shaft 35 is fixed to a fulcrum of the blocking frame 32.
The cutoff control arm 36 is fixed to the other end of the arm. A roller 37 is provided at an end of the shutoff control arm 36, and the roller 37 is in contact with a shutoff control cam 38 described later.

A helical gear 39 is meshed with a helical gear 31 fixed to the drive shaft 28, and the helical gear 39 is fixed to a looper shaft 40 extending forward and backward. A rotary looper 41 is fixedly supported at the front end of the looper shaft 40, and a worm 42 is fixedly supported at the rear end. As shown in FIG. 2, the rotary looper 41 is disposed below the needle plate 24 and a needle 6 described later.

A worm gear 43 meshes with the worm 42, and the worm gear 43 is fixedly supported by a cam shaft 44 extending left and right. This camshaft 44
, A left-right feed cam 45, a front-rear feed cam 46, and a cutoff control cam 38 are fixed. The shutoff control cam 38 has cam portions 38a and 38b, and the rollers 37 come into contact with the cam portions 38a and 38b.
Separate pins (not shown) are engaged with the grooves 45a of the left and right feed cams 45 and the grooves 46a of the front and rear feed cams 46, respectively. A link mechanism is connected to these pins. Is connected to the knob device.
The pins move along the shapes of the grooves 45a and 46a, and the knob device 10 operates via the link mechanism in conjunction with the movement of the pins. When the knob device 10 is operated, the button clamp 17 and the lower plate 11 are simultaneously moved in the horizontal direction, and the needle drop position for the button held by the button clamp 17 is adjusted.

Further, a vertically extending crank rod 47 is provided.
An eccentric cam 30 is connected to the lower end of the needle rod, and one end of a needle drive lever 48 is rotatably connected to the upper end of the crank rod 47. The needle drive lever 48 extends back and forth, and is rotatably supported by the sewing machine frame 2 at an intermediate portion of the needle drive lever 48. A needle bar 49 extending vertically is provided at the other end of the needle drive lever 48, and the needle 6 is provided at a lower end of the needle bar 49.

The balance 8 is connected to the needle bar 49.
The balance 8 also moves up and down at the same time as the needle bar 49 moves up and down. Then, as shown in FIG.
It projects from the inside of the sewing machine arm 3 to the front of the sewing machine arm 3. The needle bar 49 protrudes from the inside of the sewing machine arm 3 below the front end of the sewing machine arm 3, and the needle 6 is arranged at a position corresponding to the button clamp 17 in plan view.

Further, as shown in FIG.
An outer peripheral cam 50 and a groove cam 51 are fixed to the looper shaft 40 near 1. A thread bias support 53 is slidably attached to the guide plate 52 fixed to the sewing machine frame 2, and a fork provided below the thread bias support 53 is fitted into the outer peripheral cam 50. Further, a yarn deviation portion 54 is slidably attached to the yarn deviation portion support 53. Also,
A roller 56 is attached to one end of a front and rear arm 55 rotatably supported by the sewing machine frame 2. One end of the yarn deviation portion 54 has a long hole, and a roller 56 is fitted into the long hole. Further, the rollers 56 are also fitted into the cam portions of the groove cams 51. As a result, the yarn deviation portion 54 is
The plane motion determined by the zero and the groove cam 51 can be performed.

With the above-described configuration, the needle 6, the rotary looper 41 and the yarn deviation portion 54 cooperate to form a yarn loop, and a new yarn loop is passed through the yarn loop to form a single ring. Sewing can be performed.

Next, a yarn tension device for adjusting the tension of the yarn will be described. As shown in FIGS. 1, 2 and 4, the thread tension device includes a thread supply unit (not shown), a balance 8, a first thread tension 58, a second thread tension 57, a third thread tension 59, It is composed of a thread pick 60, thread guides 61 to 63, a solenoid 64 and the like.

One end of a thread puller 60 is connected to the end of the presser lifting lever 14 to which the presser link 13 is connected. This thread pick 60 is used for the sewing machine frame 2.
It protrudes upward from the inside of the sewing machine arm 3, and one end thereof swings back and forth in conjunction with the rotation of the moving knife 23 by the press-up solenoid 12. A thread guide 61 extending forward and backward is provided above the sewing machine arm 3 at a position corresponding to the front and rear of the thread puller 60. This yarn guide 61 has through holes 61a and 61b penetrating left and right at the front end and the rear end, respectively.

A second thread tensioner 57 and a first thread tensioner 58 are provided above the sewing machine arm 3, and a third thread tensioner 59 is provided at the front of the sewing machine arm 3.
Further, the second thread tension 57 is disposed behind the thread pick 60, and the first thread tension 58 is disposed in front of the thread pull 60. The third thread tension 59 is a balance 8 that moves up and down.
Is located below the bottom dead center. A thread guide 62 is provided at the upper front end of the sewing machine arm 3, and a thread guide 63 is provided near the bottom dead center of the balance 8 which moves up and down. A thread supply unit (not shown) is provided behind the second thread tensioner 57.

Then, the yarn supplied from the yarn supply section is supplied to the second thread tension 57 and the through hole 61 of the thread guide 61 in this order.
b, the through hole 61 a of the thread guide 61, the thread puller 60, the first thread tension 58, the thread guide 62, the thread guide 63, the balance 8, and the third thread tension 59 are guided, and finally inserted into the hole of the needle 6. Have been.

The second thread tension 57 has a tension plate,
By increasing or decreasing the pressing force applied to the yarn from the tension tray, the yarn between the yarn supply unit and the second yarn tension 57 and the yarn between the second yarn tension 57 and the first yarn tension 58 It is possible to adjust the tension (yarn tension) of the yarn. The pressing force applied to the yarn from the second yarn tensioner 57 is adjusted by adjusting the displacement of the spring.

The first thread tension 58 also has a tension plate, and the pressing force applied to the yarn from the tension plate is increased or decreased, so that the tension between the second thread tension 57 and the first thread tension 58 is increased. The tension (yarn tension) can be adjusted for the intermediate yarn and the yarn between the first yarn tension 58 and the third yarn tension 59. The thrust of the solenoid 64 allows the pressing force applied to the thread from the first thread tensioner 58 to be continuously changed during sewing.

The third thread tension 59 is applied to the thread by applying a pressing force to the first thread tension 58 and the third thread tension 5.
9 and the yarn between the third thread tension 59 and the cloth, and the third thread tension 59 applies a constant tension to the thread.

The balance 8 rises at the same time as the needle 6 rises.
At this time, since the balance 8 moves away from the thread guide 63, the path of the thread between the thread supply unit and the needle is increased, and the thread is pulled. At this time, by adjusting the pressing force of the first thread tensioner 58 by the solenoid 64, it is possible to adjust whether the balance 8 pulls the thread from the thread supply unit or the thread from the needle 6. it can.

Although not shown, the chain stitch sewing machine 1
A control device for controlling the operation of the sewing machine is provided. The control device controls the thread tension device to adjust the pressing force (thread tension) applied to the yarn. This controller is
An encoder (not shown) that detects the rotation state of the sewing machine and outputs a signal, and a CPU (Central Process)
ing Unit) and a ROM (Read Only Memory) in which a control program and control data are stored.
ry) and a RAM (Ran) serving as a work area of the CPU.
dam Access Memory), a drive driver for controlling the lifter solenoid 12 and the solenoid 64 based on a control program and control data, and the like. Each unit is connected by a bus such as a data bus. With this control device, the solenoid 64
Is controlled to adjust the pressing force applied from the first thread tensioner 58 to the yarn. Further, the operation timing of the solenoid 64 is controlled by this control device. That is, the rotation state of the sewing machine is detected by the encoder, and the state is output to the CPU. Thereby, C
The PU grasps the vertical position of the needle 6 and the rotational position of the rotary looper 41, and operates the solenoid 64 at a predetermined timing to adjust the pressing force applied to the yarn from the first thread tensioner 58.

More specifically, during single-ring sewing, the solenoid 64 is controlled so as not to apply a pressing force from the first thread tensioner 58 to the thread. Then, the rotation state of the sewing machine is detected by the encoder, and in the thread knotting operation in the final stage of the single-ring stitching, when the last needle drop is performed and the needle is raised and the thread is cut, the first A pressing force is applied to the thread from one thread tensioner 58. The solenoid 64 is drive-controlled so that the pressing force applied to the yarn from the first thread tension 58 is higher than the pressing force applied to the yarn from the second thread tension 57. Then, when the needle 6 moves up after the final needle drop, the drive of the solenoid 64 is controlled so as to apply a pressing force to the thread from the first thread tensioner 58 so as to tighten the stitch by the thread loop.

Next, the operation of the chain stitch sewing machine 1 having the above configuration will be described. When a start lever (not shown) is depressed, the shut-off frame 32 rotates in the direction A, and the shut-off hook 3
The engagement between the drive pulley 27 and the cam portion 29a is released, and the drive pulley 27 and the drive shaft 28 are connected by the above-described blocking mechanism, and start rotating in the B direction.

As a result, the cam shaft 44 also rotates in the direction C, and the control arm 36 is connected to the cam portion 38b of the control cam 38.
Even when the roller 37 gets on and the foot is released from the above-described activation lever, the blocking hook 34 cannot rotate in the anti-A direction,
The rotation of the drive shaft 28 continues.

By the operation of the eccentric cam 30, the needle drive lever 48 swings via the crank rod 47, and the needle bar 49 and the balance 8 reciprocate up and down. Then, the single ring sewing is formed by the vertical movement of the needle 6, the rotation in the direction D of the rotary looper 41 attached to the tip of the looper shaft 40, and the cooperation of the operation of the thread deviation portion 54.

That is, the needle 6 falls into the button hole of the button on the cloth in a predetermined order by the above operation and the movement of the button clamp 17 by the rotation of the left and right feed cam 45 and the front and rear feed cam 46, and the needle 6 is simply dropped. A chain stitch is formed.

When the roller 37 reaches the cam portion 38a of the shutoff control cam 38, the shutoff frame 32 rotates in the direction opposite to the direction A, and the shutoff hook 34 contacts the shutoff cam 29. At this time, the link between the drive pulley 27 and the drive shaft 28 is released by the above-described blocking mechanism, and thereafter, the drive shaft 28 rotates by inertial force, and the front end 34 a of the blocking hook 34 and the blocking cam 29.
Cam portion 29a comes into contact and stops. Thereby, the needle 6
And the vertical movement of the balance 8 also stops.

Next, the presser lifting solenoid 12 is operated, and the presser lifting link 13 swings rearward. As a result, the thread cutting lever 18 and the thread cutting arm 19 rotate, and the thread cutting link 22 swings forward. And moving knife 23
Is rotated, and the thread is cut by the moving knife 23 and the fixed knife 25. At the same time, the presser lifting lever 14 rotates and the thread picker 60 swings backward, so that the path of the thread increases, and the thread is pulled out from the thread supply unit. Also,
When the presser lifting lever 14 rotates, the protrusion 14a and the hook 10a come into contact with each other, and the knob device 10 and the button clamp 17 rise. However, there is play between the protrusion 14a and the hook 10a. Then, the knob device 10 and the button clamp 17 move up later than the cutting of the thread.

The details of the operation of the single chain stitch and the operation of the thread knot in the final stage of the single chain stitch will be described with reference to FIGS. FIG. 6 shows a state of single-ring sewing performed in the first embodiment. FIG. 7 is a time chart showing the operation of the needle 6, the first thread tension 58, and the second thread tension 57. 8 to 17 show the needle 6, the rotary looper 41, and the yarn deviation portion 5 in the yarn knotting operation.
The cooperative relationship and the positional relationship of No. 4 are sequentially shown in order, and in each drawing, (A) is a cross-sectional view, (B) is a perspective view, 100 is a thread, and 202 is a button. . Note that FIG. 6 shows a case where the single-ring sewing is performed linearly. Since the single-ring sewing is actually performed on the button holes in a predetermined order, the single-ring sewing is linearly performed. It does not do it.

First, the pressing force applied to the yarn by the second yarn tensioner 57 is adjusted to adjust the tension of the yarn. The pressing force of the second thread tensioner 57 is set so that the thread loop is not completely drawn to the cloth 201 when the balance 8 is raised and the thread is pulled. Further, the solenoid 64 is controlled by the control device so that the pressing force applied to the yarn by the first thread tension 58 is reduced to zero, and the first thread tension 58 is adjusted so that no tension is applied to the thread.

When the pressing force applied to the yarn from each yarn tension is adjusted and the start lever (not shown) is depressed, as described above,
The drive pulley 27 and the drive shaft 28 are connected by the blocking mechanism, and single-ring sewing starts (time 0). When the needle 6 falls into the button hole and penetrates the back of the cloth 201, the rotary looper 41 captures the yarn from the needle 6 (time T1), and forms a yarn loop. Then, when the needle 6 is raised and the needle is dropped in the next predetermined buttonhole, the rotary looper 41 catches the yarn and forms a new yarn loop (time T2). This new thread loop is passed through the previously formed thread loop, and the capture of the previously formed thread loop by the rotary looper 41 is released, and the needle 6 rises (between time T2 and time T3). At this time, the thread path is increased by the lifting of the balance 8, so that the thread is pulled. However, the adjustment of the pressing force by the second thread tensioner 57 causes the previously formed thread loop to bend. Is not completely attracted to the cloth 201 (FIG. 6). The above operation is repeated (from time T3 to time T5), and as shown in FIG. 6, the yarn loop 200 is completely bent while the yarn loop 200 is bent.
A soft single-ring stitch is formed so that it is not attracted to 01. The stitches of this single-ring stitch are looser stitches than the normal single-ring stitch, and the thread loop 200 (thread 1) forming the stitch is formed.
00) and the cloth 201 are formed. That is, the pressing force is given to the thread only by the second thread tensioner 57, and since this pressing force gives a weaker pressing force than the normal chain sewing,
The thread loop 200 (thread 100) forming the stitch is in a slack state.

Next, a yarn knotting operation is performed. Time T4
FIG. 8 shows a state in which the first thread loop 100a (a thread loop formed at the time of needle drop before the last needle drop) is formed and the needle 6 is raised. FIG. 8 shows the state at time T5.

Next, the needle 6 is positioned on the needle drop position (another buttonhole) immediately before the final needle drop, and the needle 6 starts to descend (FIG. 9). When the needle 6 further starts to move down after lowering, the rotary looper 41 starts catching the yarn from the needle 6, and the yarn deviation portion 54 comes into contact with the first yarn loop 100a (at the time shown in FIGS. 10 and 7). T6).

Thereafter, the needle 6 further rises, and the yarn deviation portion 5
4 is separated from the first thread loop 100a and the rotary looper 4
1 forms a second yarn loop 100b, and passes the second yarn loop 100b through the first yarn loop 100a to form the first yarn loop 100a.
Is detached from the rotary looper 41 (FIG. 11). In this state, since the pressing force applied to the yarn from the second thread tension 57 is such that the first yarn loop 100a is not completely drawn to the cloth, the balance 8 pulls the yarn from the yarn supply unit. Since the first yarn loop 100a is pulled, the length of the yarn forming the first yarn loop 100a becomes longer, and the first yarn loop 100a is bent.

At this point, the last needle starts to drop into the same buttonhole as the previous needle drop buttonhole, and the second thread loop 100b is moved to one side by the thread deviation portion 54, and the rotary looper 41 is moved.
Starts to capture the yarn from the needle 6 (FIG. 12), the solenoid 64 operates to apply a pressing force to the yarn from the first thread tensioner 58 (time T7 in FIG. 7). At this time, the first thread tension 58
The pressing force applied to the yarn from the second thread is made larger than the pressing force applied to the yarn from the second yarn tensioner 57. Next, the rotary looper 41 starts passing the captured yarn through the second yarn loop 100b, and the yarn deviation portion 54 is separated from the second yarn loop 100b (FIG. 13). In this state, the first thread tension 58
In the same manner, the second thread loop 100b abuts on the thread deviation portion 54 to increase the thread path, and the single-ring stitches performed up to that point (that is, , From the thread loop 200). This allows
When the yarn deviation portion 54 is separated from the second yarn loop 100b, the length of the yarn forming the second yarn loop 100b becomes longer, and the second yarn loop 100b is bent.

Thereafter, a third yarn loop 100c passing through the second yarn loop 100b is formed (FIG. 14). Further, the needle 6 is raised, and the third thread loop 100c is pulled down (FIG. 15). As described above, the first yarn loop 1
00a and the second thread loop 100b are deflected so that the first thread tension 58
From the third yarn loop 10
The first thread loop 100a is also pulled along with 0c and passes through the second thread loop 100b (FIG. 16).

The third thread loop 100c is pulled down as it is, and as described above, the linkage between the drive pulley 27 and the drive shaft 28 is released by the blocking mechanism, and the vertical movement of the needle 6 and the balance 8 is stopped (see FIG. 7). T8). Then, the presser lifting solenoid 12 is operated, and the moving knife 23 and the fixed knife 25 are operated (FIG. 16), whereby the third thread loop 100c is cut (time T9 in FIGS. 17 and 7), and then. Then, the button clamp 17 is raised to release the clamp of the cloth (time T10 in FIG. 7). At this time, when the thread picker 60 swings backward, the path of the thread increases, and the thread is pulled out for the next sewing operation. However, the pressing force applied to the thread from the first thread tensioner 58 is reduced. Since the pressing force applied to the yarn from the second thread tensioner 57 is greater than the pressing force applied to the yarn, the yarn inserted through the needle 6 does not come off from the needle 6, and the yarn is pulled out from the yarn supply unit.

The knot formed as described above is a knot in which the knot formed by the first yarn loop 100a is fastened by the knot formed by the second yarn loop 100b. In other words, the knot is connected to the end 10 of the thread.
0d has passed through the first thread loop 100a, and the end portion 100d of the thread that has passed through the first thread loop 100a is:
After straddling two of the yarns forming the first yarn loop 100a (that is, the second yarn loop 100b is
00a), once again the first yarn loop 10
It is a knot that passes through 0a. In other words, the portion of the yarn 100 that is more distal than the first yarn loop 100a has passed through the first yarn loop 100a twice, and once passed through the first yarn loop 100a, Since the first thread loop 100a has passed through the first thread loop 100a again from the same side as the first thread loop, the first thread loop 100a has passed through the thread end 100.
Even if d comes out once, the yarn end 100d is still tied by the yarn loop 100a, and the knot is not completely frayed.

Referring to FIG. 18, the end portion 100d (FIG. 18A) of the knot yarn thus formed is firstly
The process exits from the first loop 100a (FIG. 18B). Even in this case, the end portion 100d of the yarn that has come off from the first yarn loop 100a has passed through the first loop 100a (FIG. 18C).

Therefore, even if the end of the yarn is pulled by rubbing against the skin or the like, the end 100d of the yarn does not fall out of the first yarn loop 100a, and the knot does not easily come off. Can be formed.

After the third thread loop 100c is formed, the pressing force is adjusted by the first thread tensioner 58 and the thread is pulled by the balance 8, so that a tight knot is formed and the thread is not easily loosened. A knot is formed. Further, in this embodiment, since the deflection of the thread is adjusted by the drive output of the solenoid 64, the thread hook 503 does not have to be provided unlike the above-mentioned conventional chain stitch sewing machine. Therefore, the knot can be formed with a very simple configuration.
Further, unlike the conventional chain stitch sewing machine, the bending of the thread loop is adjusted by electrically controlling the solenoid 64 without mechanically adjusting the bending of the thread hooking portion 503. The number of movable parts is relatively smaller than that of the sewing machine, and the reliability of the sewing machine is improved.

<Second Embodiment> A thread tension device according to a second embodiment of the present invention will be described. First, the configuration will be described. In this embodiment, FIGS.
Therefore, the second embodiment has the same configuration as that of the first embodiment, and a description thereof will be omitted. A different configuration will be described.

Although not shown, the chain stitch sewing machine 1 according to the second embodiment has a control device for controlling the operation of the sewing machine. The thread tension device includes a control device that controls adjustment of the tension of the yarn. The control device detects a rotation state of the sewing machine, and outputs a signal (not shown) to an encoder.
CPU (Central Processing Un
it), a ROM (Read Only Memory) in which a control program and control data are stored, and a RAM (Random Ac) serving as a work area of the CPU.
ESS, a lifter solenoid 12 and a solenoid 64 based on a control program and control data.
And the like. Each unit is connected by a bus such as a data bus. The control device controls the driving of the solenoid 64 to adjust the pressing force applied from the first thread tensioner 58 to the yarn. Further, the operation timing of the solenoid 64 is controlled by this control device. That is, the rotation state of the sewing machine is detected by the encoder, and the state is output to the CPU. Accordingly, the CPU grasps the vertical position of the needle 6 and the rotational position of the rotary looper 41, operates the solenoid 64 at a predetermined timing, and adjusts the pressure applied to the yarn from the first thread tensioner 58.

More specifically, unlike the first embodiment, when performing single-ring sewing, the first thread tension 5
The drive of the solenoid 64 is controlled so as to apply a pressing force to the yarn from the position 8. Then, after the needle is dropped two times before the final needle drop and the needle 6 has risen and reached the top dead center later, no pressing force is applied to the thread from the first thread tensioner 58. Thus, the drive of the solenoid 64 is controlled. Further, when the thread rises after the final needle drop, the drive of the solenoid 64 is controlled so that a pressing force for tightening the stitch by the thread loop is applied to the thread from the first thread tensioner 58.

The details of the operation of single chain stitching and the operation of thread knotting in the final stage of single chain stitching will be described with reference to FIGS.
This will be described with reference to FIGS. 19 and 20. FIG.
6 is a time chart showing the operation of a needle 6, a second thread tension 57, and a first thread tension 58. FIG. 20 shows a state of single-ring sewing performed in the second embodiment. FIG. 20 shows a case where the single-ring sewing is performed linearly. Since the single-ring sewing is actually performed on the button holes in a predetermined order, the single-ring sewing is linearly performed. It does not do it.

First, as shown in FIG. 19, the tension applied to the yarn is adjusted by adjusting the pressing force applied to the yarn by the second yarn tensioner 57. Further, the control device controls the solenoid 64 to apply a pressing force to the yarn by the first thread tension 58, and to apply a tension to the thread from the first thread tension 58. In addition,
Due to the pressing force of the second thread tension 57 and the pressing force of the first thread tension 58, when the thread is pulled during single-ring sewing, the thread loop is completely drawn to the cloth 201, and the thread loop is bent. The pressing force is set so as not to be excessive. Further, when the pressing force of the second thread tension 57 is not applied to the thread from the first thread tension 58, when the balance 8 pulls the thread, the thread loop is not completely drawn to the cloth 201. , The pressing force such that the yarn loop is bent.

When the pressing force applied to the thread from each thread tension is adjusted and the start lever (not shown) is depressed, the drive pulley 27 and the drive shaft 28 are connected by the above-mentioned blocking mechanism, and single-ring sewing is started ( Time 0). When the needle 6 falls into the buttonhole and penetrates the back of the cloth 201, the rotary looper 41 captures the yarn from the needle 6 (time T11) and forms a yarn loop. Then, when the needle 6 is raised and the needle is dropped in the next predetermined buttonhole, the rotary looper 41 catches the yarn and forms a new yarn loop (time T12). While passing this new yarn loop through the yarn loop formed earlier,
The capture of the previously formed yarn loop by the rotary looper 41 is released, and the needle 6 rises (from time T12 to time T13).
while). At this time, the thread path is increased by raising the balance 8, and the thread is pulled. However, the adjustment of the pressing force by the second thread tension 57 and the first thread tension 58 causes the previously formed thread loop. Is completely drawn to the cloth 201 (FIG. 20). By repeating the above operation (between time T13 and time T15), as shown in FIG. 20, a hard single-ring stitch is formed such that the thread loop 200 is completely drawn to the cloth 201. At this time, the thread loop 200 forming the seam
Is not bent.

Next, a yarn knotting operation is performed. Time T1
FIG. 8 shows a state where the first thread loop 100a (the thread loop formed at the time of the needle drop two times before the final needle drop) is formed at 4, and the needle 6 is raised. FIG. 8 shows the state at time T15. At this time T15,
The control device controls the solenoid 64 to reduce the pressing force applied to the yarn from the first thread tension 58 to zero and apply the pressing force to the yarn only from the second thread tension 57.

Next, the needle 6 is located on the needle drop position (another buttonhole) immediately before the final needle drop, and the needle 6 starts to descend (FIG. 9). When the needle 6 further descends and then starts to ascend, the rotary looper 41 starts catching the yarn from the needle 6, and the yarn deviation portion 54 comes into contact with the first yarn loop 100a (the time in FIGS. 10 and 19). T16).

Thereafter, the needle 6 further rises, and the yarn deviation portion 5
4 is separated from the first thread loop 100a and the rotary looper 4
1 forms a second yarn loop 100b, and passes the second yarn loop 100b through the first yarn loop 100a to form the first yarn loop 100a.
Is detached from the rotary looper 41 (FIG. 11). In this state, since the pressing force is given only by the second thread tension 57, the length of the thread forming the first thread loop 100a becomes longer, and the first thread loop 100a is bent, The yarn loop 100a is not completely drawn to the cloth 201.

At this point, the last needle starts dropping into the same buttonhole as the previous needle drop buttonhole, and the second yarn loop 100b is moved to one side by the yarn deviation portion 54, and the rotary looper 41 is moved.
Starts to capture the yarn from the needle 6 (FIG. 12), the solenoid 64 operates to apply a pressing force to the yarn from the first thread tensioner 58 (time T17 in FIG. 19). At this time, the pressing force applied to the yarn from the first thread tension 58 is the same as previously (time 0 to time T).
By 15), the tension is greater than the tension applied from the first thread tensioner 58 to the yarn, and is greater than the pressing force applied to the yarn from the second tensioner 57. Next, the rotary looper 41 starts passing the captured yarn through the second yarn loop 100b, and the yarn deviation portion 54 is separated from the second yarn loop 100b (FIG. 13). In this state, similarly, the second yarn loop 100b and the yarn deviation portion 54 come into contact with each other, the path of the yarn increases, and the yarn is pulled.
0b, the first yarn loop 100a
Since a part of the warped yarn is pulled by the second yarn loop 100b, the length of the yarn forming the second yarn loop 100b becomes longer, and the second yarn loop 100a is bent. .

Thereafter, a third yarn loop 100c passing through the second yarn loop 100b is formed (FIG. 14). Further, the needle 6 is raised, and the third thread loop 100c is pulled down (FIG. 15). As described above, the first yarn loop 1
00a and the second thread loop 100b are deflected so that the first thread tension 58
The third yarn loop 100
Along with c, the first yarn loop 100a is also pulled and passes through the second yarn loop 100b (FIG. 16).

The third thread loop 100c is pulled down as it is, and as described above, the linkage between the drive pulley 27 and the drive shaft 28 is released by the blocking mechanism, and the vertical movement of the needle 6 and the balance 8 is stopped (FIG. 19). Time T18). Next, the presser lifting solenoid 12 is operated to move the moving knife 23 and the fixed knife 25.
Operates (FIG. 16), whereby the third yarn loop 100
c is cut off (time T19 in FIGS. 17 and 19), and then the button clamp 17 rises to release the cloth from being clamped (time T20 in FIG. 19). At this time, the thread picker 6
By swinging 0 backward, the path of the yarn increases,
Although the yarn is pulled out, the pressing force applied to the yarn from the first yarn tensioner 58 is greater than the pressing force applied to the yarn from the second yarn tensioner 57. The yarn is pulled out from the yarn supply unit without falling out of the yarn supply unit 6.

The knot formed as described above is a knot in which the knot formed by the first yarn loop 100a is fastened by the knot formed by the second yarn loop 100b. In other words, the knot is connected to the end 10 of the thread.
0d has passed through the first thread loop 100a, and the end portion 100d of the thread that has passed through the first thread loop 100a is:
After straddling two of the yarns forming the first yarn loop 100a (that is, the second yarn loop 100b is
00a), once again the first yarn loop 10
It is a knot that passes through 0a. This knot is similar to that of the first embodiment described above.

In each of the above embodiments, the specific detailed structure can of course be variously changed without departing from the gist of the invention.

[0085]

As described above, according to the first aspect of the present invention, the thread tension device causes the thread loop formed at least one before the final needle to be bent and is formed by the final needle drop. When the third thread loop is drawn, the third thread loop is formed by the needle drop two before the final needle drop in order to set the thread tension so that the thread loop does not bend. Pulling one thread loop, this pulled first thread loop passes through a second thread loop formed just before the final needle,
This allows the first thread loop to form a knot fastened by the second thread loop. This knot is very hard to fray and the ring seam is not frayed. Further, since a hard knot is formed, the knot is not easily frayed, and the ring seam is not easily frayed. Further, since the knot is formed by the electrical control, the number of movable parts is reduced and the reliability is improved as compared with the case where the knot is formed by the mechanical control.

According to the second aspect of the present invention, the yarn loop is bent so as to bend the yarn loop formed at least one before the final needle and when the third yarn loop is pulled. The third yarn loop pulls the first yarn loop to adjust the pressure applied to the yarn from the yarn tension by the pressure adjusting means. To pass through the thread loop, the first thread loop can form a knot fastened by the second thread loop. Since the knot is not easily frayed, the ring seam is less likely to be frayed.

According to the third aspect of the present invention, the first yarn loop can form a knot fastened by the second yarn loop. Therefore, the first thread loop can form a knot fastened by the second thread loop, and the ring seam is less likely to fray.

According to the fourth aspect of the present invention, the first yarn loop can form a knot fastened by the second yarn loop. Therefore, the first thread loop can form a knot fastened by the second thread loop, and the ring seam is less likely to fray.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an appearance of a chain stitch sewing machine as an example to which the present invention is applied.

FIG. 2 is a perspective view schematically showing the inside of the chain stitch sewing machine.

FIG. 3 is a perspective view schematically showing the inside of the chain stitch sewing machine.

FIG. 4 is a plan view showing an upper surface portion of a sewing arm of the chain stitch sewing machine.

FIG. 5 is a perspective view showing a main part of the chain stitch sewing machine for cutting a thread.

FIG. 6 is a drawing for explaining a chain stitch formed by the chain stitch sewing machine according to the first embodiment of the present invention.

FIG. 7 is a time chart showing the operation of the chain stitch sewing machine according to the first embodiment of the present invention.

FIG. 8 is a drawing showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 9 is a view showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 10 is a view showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 11 is a drawing showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 12 is a drawing showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 13 is a drawing showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 14 is a view showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 15 is a drawing showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 16 is a drawing showing a knot forming process in the first embodiment and the second embodiment of the present invention.

FIG. 17 is a drawing showing knots formed in the first embodiment and the second embodiment of the present invention.

FIG. 18 is a drawing for explaining knots formed in the first embodiment and the second embodiment of the present invention.

FIG. 19 is a time chart showing the operation of the chain stitch sewing machine according to the second embodiment of the present invention.

FIG. 20 is a view for explaining a chain stitch formed by the chain stitch sewing machine according to the second embodiment of the present invention.

FIG. 21 is a view showing a knot forming process in a conventional chain stitch sewing machine.

FIG. 22 is a view showing a knot forming process in a conventional chain stitch sewing machine.

FIG. 23 is a view showing a knot forming process in a conventional chain stitch sewing machine.

FIG. 24 is a view for explaining a knot formed in a conventional chain stitch sewing machine.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Chain stitch sewing machine 6 Needle 8 Balance 12 Lifting solenoid 41 Rotary looper 57 Second thread tension (thread tension device) 58 First thread tension (thread tension, thread tension device) 59 Third thread tension 60 Thread picking 61 thread guide 62 thread guide 63 thread guide 64 solenoid (pressure adjusting means, thread tension device) 100 thread 100a first thread loop (thread loop formed at the needle drop just before the last needle drop) 100b second Thread loop (thread loop formed at the needle drop just before the last needle drop) 100c Third thread loop (thread loop formed at the last needle drop) 100d End of thread 200 thread loop 201 cloth

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3B150 AA04 AA23 BA06 BB01 CE01 CE27 FD07 FD09 FH11 GD14 GF02 GF03 JA11 LA02 LA84 LA89 LB01 NA02 NA71 NA76 NB15 NB16 NC11 QA01 QA04

Claims (4)

[Claims] A needle that moves up and down by inserting a thread, a rotary looper that captures the thread from the needle, and forms a thread loop by pulling the captured thread; A thread tension device for setting a thread tension so as to adjust the bending of the sewing machine, and a chain stitch sewing machine forming a chain stitch by cooperation of the needle and the rotary looper, wherein the thread tension device is When the rotary looper forms a thread loop at least one before the final needle drop, the thread tension is set so that the thread loop bends, and the rotary looper forms a thread loop of the final needle drop. , A thread stitch is set so that a thread loop is not bent. 2. A chain stitch sewing machine according to claim 1, wherein said thread tension device applies a pressure to a thread on a path from said thread supply section to said needle. When the rotary looper forms a yarn loop at least one before the final needle drop, the yarn loop is bent and the rotary looper is driven by the electrical control. A chain stitch sewing machine comprising: a pressure adjusting means for changing a pressure of the thread tension so that the thread loop does not bend when a falling thread loop is formed. 3. The chain stitch machine according to claim 2, wherein the thread tension device includes a second thread tensioner that applies pressure to a thread on a path from the thread supply unit to the thread tension. Until the needle starts rising after the last needle drop after the needle starts dropping, apply pressure to the thread only with the second thread tension,
After bending the thread loop formed from the first needle drop to just before the last needle drop, and after the needle starts rising after the final needle drop, the pressure adjusting means moves the thread tension from the thread tension to the thread. A chain stitch sewing machine wherein a pressure applied is increased to apply a pressure to the thread from the thread tension and the second thread tension so that a thread loop of a final needle drop does not bend. 4. The chain stitch sewing machine according to claim 2, wherein the thread tension device includes a second thread tensioner that applies pressure to a thread on a path from the thread supply unit to the thread tension. Until the needle starts to drop just before the final needle drop after the needle drops, pressure is applied to the thread from the above thread tension and the second thread tension, and the needle from the first needle drop to the final needle drop The pressure adjusting means keeps the thread loop formed up to just before the needle loop from bending before the needle starts dropping just before the final needle drop until the needle starts rising after the last needle drop. After the pressure applied to the yarn from the tone is reduced, the yarn loop formed immediately before the final needle drop is deflected, and after the needle has started to rise after the final needle drop, the pressure adjusting means is operated by the pressure adjusting means. The pressure applied to the yarn from the tension is increased, and pressure is applied to the yarn from the thread tension and the second thread tension, A chain stitch sewing machine characterized in that the thread loop of the last needle drop is not bent.