JPH05245287A - Sewing machine thread cutting device - Google Patents

Abstract

(57) [Summary] [Purpose] After the thread trimming, the upper thread is not held by the lower thread holding spring and the remaining length of the upper thread is stable, so that the seam is reliably formed at the start of the next sewing. The purpose is to do. [Structure] A hook on the moving blade that separately captures the upper thread and the lower thread when cutting the thread, a hook on the moving blade that separates the upper thread and the lower thread, the fin of the outer hook, and the upper thread after cutting. It consists of a relief groove on the moving blade that prevents the thread from being held by the bobbin thread holding spring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread cutting device of a sewing machine for cutting upper and lower threads connected to a work cloth at the end of sewing.

[0002]

2. Description of the Related Art As a thread cutting device for a sewing machine, there is, for example, one disclosed in Japanese Patent Laid-Open No. 61-238290. As shown in FIG. 8, this thread cutting device is provided near the outer hook 200 at the bottom of the needle plate. Outer pot 20
0 is rotatable about one vertical axis, and a catching beak 204 for catching the needle thread 202 is provided on a part of the outer circumference. An inner hook 208 is non-rotatably held in the outer hook 200, and a bobbin 212 wound with a lower thread 210 is relatively rotatably accommodated in the inner hook 208. Further, a protrusion 214 is provided on the outer periphery of the outer pot 200 so as to face the catching beak 204.

The yarn cutting device includes a movable blade 220 having a cutting blade 218. The movable blade 220 is arranged so as to be movable with respect to the machine frame, and a thread hooking portion 222 for catching the upper thread 202 and the lower thread 210 is formed on the side opposite to the outer hook 200 side. , A thread separating section 224 for separating the upper thread 202 and the lower thread 210 into the thread hooking section 222 at the tip end thereof.
Are formed. In this yarn cutting device, the movable blade 220 also serves as a yarn hooking member. Further, a notch 226 is formed in a side portion of the movable blade 220 on the side closer to the outer hook 200, and together with the protrusion 214 provided on the outer hook 200, the upper thread 202 and the lower thread 210 are directed in different directions. A thread dividing means for dividing the yarn so as to extend is configured.

A fixed blade 230 shown by a two-dot chain line in the figure is fixed to the lower surface of the needle plate, and the movable blade 220 is fixed blade 23.
By moving relative to 0, the upper and lower threads 202 and 210 are cut by the cutting blade 232 of the fixed blade 230 and the cutting blade 218 of the movable blade 220. The movable blade 220 and the fixed blade 230 constitute a cutting means.
Further, a pressing member 236 made of an elastic material is fixed to the side of the machine frame of the sewing machine, and a tip end portion of the pressing member 236 elastically contacts the lower surface of the movable blade 220.

At the time of sewing, a pair of needles (not shown) carrying the upper thread 202 descend and pass through the work cloth, and then are inserted into the needle insertion holes 242 of the feed dog 240. The loop of the upper thread 202 formed as the needle rises is caught by the catching beak 204 of the outer hook 200 that rotates, and the upper thread 202 and the lower thread 210 are entangled by one rotation of the outer hook 200. A seam is formed.

On the other hand, at the time of thread cutting, after the loop of the upper thread 202 is captured by the capturing bevel 204, the movable blade 220 is advanced and the thread separating section 224 causes the upper thread 202 and the lower thread 21 to move.
0 is dealt with. When the movable blade 220 is retracted, the upper thread 202 and the lower thread 210 are captured by the thread hooking portion 222, and the needle side portion 248 of the thread loop of the upper thread 202 is moved by the movable blade 22.
The notch 226 of 0 and the protrusion 214 of the outer hook 200 are also captured, and the upper thread 202 and the lower thread 210 are held in the thread hooking section 222 in a separated state. When the movable blade 220 is further retracted, the area around the thread hooking portion 222 of the movable blade 220 is pressed by the pressing member 2.
The needle side portion 248 of the upper thread 202 and the lower thread 210 are overlapped with the distal end of the movable thread 2 by the pressing member 236.
The lower surface of 20 is pressed and held. Then, the cutting side 232 of the fixed blade 230 and the cutting side 218 of the movable blade 220 cut the cloth side portion 250 of the upper thread 202 and the lower thread 210, respectively. After the cutting is completed, the needle side portion 248 of the needle thread 202 is moved to the pressing member 236 and the movable blade 220 by a wiper device or the like.
It is pulled out from between and raised with the needle.

[0007]

However, in the yarn cutting device described above, although the positions of the upper yarn 202 and the lower yarn 210 are separated by the yarn dividing means, both yarns are attached to one yarn hooking portion 222. Since the threads 202 and 210 are captured and held together by the pressing member 236, when the upper thread 202 is pulled out from between the pressing member 236 and the movable blade 220, the lower thread 210 is moved to the upper thread 202. There were times when I got out. If the next sewing is started in the state where the lower thread is not held as described above, there is a problem that the first stitch cannot be reliably formed. The present invention has been made in view of this problem, and an object thereof is to obtain a thread cutting device capable of reliably holding a lower thread after cutting and reliably forming a next stitch.

[0008]

The gist of the present invention is, in a thread cutting device of a sewing machine including the thread hooking member, the thread dividing means, the cutting means and the pressing member, for catching a lower thread in a thread hooking portion. One thread hooking portion and a second thread hooking portion for catching the upper thread are separately provided at different positions of the thread hooking member, and at least one of the thread hooking member and the pressing member is threaded by a lower thread. The relief thread is formed at the position where the upper thread separated from the second thread hook extends from the second thread hooking portion.

[0009]

In the thread cutting device of the sewing machine configured as described above, the bobbin thread is captured at the first thread hooking portion of the thread hooking member and the upper thread is caught at the second thread hooking portion during thread cutting. The upper thread and the lower thread caught by the respective thread hooks are made to extend in different directions by the thread dividing means. Then, when the thread hooking member retracts and the pressing member is in a state of pressing the thread hooking member, the lower thread is sandwiched between the pressing member and the thread hooking member and pressed against the thread hooking member to be held, Since the needle side portion of the upper thread extends in the relief groove, it cannot be pressed against the thread hooking member.

[0010]

As described above, the upper thread extends in a different direction from the lower thread from the second thread hooking section different from the first thread hooking section on which the lower thread is hooked, and is completely separated from the lower thread. Therefore, when the upper thread is pulled out from between the thread hooking member and the pressing member, it is possible to favorably prevent the lower thread from being pulled out together.
Moreover, since the upper thread extends in the clearance groove, it is not sandwiched between the thread hooking member and the pressing member, and even if the upper thread is thicker than the lower thread, the lower thread reliably presses the thread hooking member. It will not be loosened when the upper thread is pulled out because it is sandwiched by the member. Therefore, the bobbin thread is surely kept held by the thread hooking member and the pressing member, and the first stitch after the resumption of sewing can be reliably formed. Further, the effect of the present invention can be enjoyed only by providing the thread hooking portion of the conventional thread hooking member at two positions and forming the escape groove, so that there is an effect that the cost is low.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a two-needle needle feed sewing machine will be described in detail below with reference to the drawings. In FIG. 5, 10 is a bed portion of the machine frame. A needle plate 12 is attached to the bed 10. Needle plate 12
An elongate hole 14 is formed in a part of the above, and a feed dog 16 is arranged so as to be capable of four feed movements. The feed dog 16 is provided with a pair of needle insertion holes 18 in parallel at approximately the center thereof (Fig. 5).
(Only one of which is shown in FIG. 2), and is projected above the upper surface 20 of the needle plate 12 through the elongated hole 14. Above the feed dog 16, a pair of needles 24 (only one of which is shown in the figure) is held by an arm portion (not shown) of the sewing machine frame,
It can be moved in the vertical direction and the cloth feed direction (the horizontal direction in the figure). Further, a presser foot 28 that presses the work cloth 26 supported by the bed portion 10 on the needle plate 12 with a strength that allows relative movement is disposed on the machine frame. When the work cloth 26 is sewn, the needle 24 is lowered with the needle thread 34 inserted in the needle hole 32, and the presser foot 28
36 formed in the base, the work cloth 26, and the feed dog 16
Of the feed dog 16 and the needle 2 in that state.
4 moves integrally to the rear so that the work cloth 26
Are sent by stitch pitch.

In the bed 10, below the feed dog 16, a pair of thread catchers 40 and a thread cutting device 42 are provided.
Are arranged. Since the pair of devices are the same, the one loop catcher 40 and the yarn cutting device 42 will be representatively described. As shown in FIG. 1, the thread catcher 40 includes an outer hook 46. The outer pot 46 has a substantially cylindrical shape with a bottom, and as shown in FIG. 5, a rotary shaft 48 provided in the bed 10 and rotatable about one vertical axis.
It is fixed to the upper end of the rotating shaft 48 and rotates integrally with the rotating shaft 48. The upper thread 3 is attached to a part of the outer circumference of the outer hook 46.
A catch beak 50 for catching the yarn wheel 60 of No. 4 is formed, and an inner hook 52 is provided in the outer hook 46 so as to be rotatable relative to it, and a hook stopper 53 of the inner hook 52 and an unillustrated rotation prevention of the needle plate 12 are provided. The rotation of the inner hook 52 is prevented by the engagement with the portion. A bobbin 56 having a lower thread 54 wound therein is rotatably accommodated in the inner hook 52. Further, a protrusion 58 is formed on the outer periphery of the outer hook 46 in a direction facing the catch beak 50.

During sewing, the needle 24 descends to move the feed dog 16
After passing through the needle insertion hole 18 of the upper needle 34, the loop 60 of the upper thread 34 formed as the needle 24 rises is captured by the catching beak 50 of the rotating outer hook 46, and is rotated by one rotation of the outer hook 46. The thread 34 and the bobbin thread 54 are entangled to form a stitch.

As shown in FIG. 1, a thread cutting device 42 is arranged near the thread catcher 40. Thread cutting device 42
Has a movable blade 64. The movable blade 64 is a long plate-shaped member, and is arranged so as to be movable in the horizontal direction with respect to the bed 10. As shown enlarged in FIGS. 6 and 7, a groove 70 extending in the longitudinal direction is formed on the upper surface 68 of the movable blade 64 in the mounted state, and a side surface opposite to the side surface 72 facing the outer hook 46. A first thread hooking portion 76 and a second thread hooking portion 78 are formed on the ball 74 at a distance in the longitudinal direction of the movable blade 64. The first thread hooking portion 76 is the lower thread 54.
The second thread hooking portion 78 catches the upper thread 34, and the thread hooking portions 76 and 78 communicate with the groove 70 on the upper surface 68 side. In this embodiment, the movable blade 6
4 also serves as a thread hooking member. In addition, the movable blade 6
As shown by the broken line in FIG. 6, an escape groove 82 is formed on the lower surface 80 in the attached state of No. 4 from the second thread hooking portion 78 to the side surface 72.

From the tip of the movable blade 64 to the first thread hooking portion 76.
The side surface 74 has a substantially circular arc shape, and this portion serves as a thread separating section 86 that separates the lower thread 54 into the first thread hooking section 76 and the upper thread 34 into the second thread hooking section 78. ..
In addition, a gentle spherical crown-shaped projection 90 is formed around the tip of the groove 70 on the upper surface 68, and partially overlaps with an elongated hole 92 formed at the tip of the groove 70. The end surface of the long hole 92 is inclined as shown in FIG. 7, and an arcuate cutting blade 94 is formed at the tip of the groove 70 at a position slightly higher than the upper surface 68.

Further, the side surface 72 of the movable blade 64 is formed with a notch 96 that cuts up in the opposite direction to the first and second thread hooking portions 76 and 78. The notch 96 cooperates with the protrusion 58 formed on the outer hook 46 to form a yarn dividing means for dividing the upper yarn 34 and the lower yarn 54.

As shown in FIG. 5, a fixed blade 100 is fixed to the lower part of the needle plate 12. A cutting edge 102 facing the cutting edge 94 of the movable blade 64 is formed at the tip of the fixed blade 100, and by the relative movement of the movable blade 64 with respect to the fixed blade 100, the two cutting edges 102, 94 are moved. Upper and lower thread 3
4, 54 are cut. In this embodiment, the fixed blade 1
00 and the movable blade 64 constitute cutting means. A pressing member 106 is further fixed inside the bed 10. The pressing member 106 is composed of a leaf spring,
As shown in FIG. 5, the pressing surface 108 formed at the tip contacts the lower surface 80 of the movable blade 64 and presses it. In the present embodiment, the protrusion 58, the movable blade 64, the fixed blade 10
0 and the pressing member 106 constitute a yarn cutting device.

Next, the cutting of the upper thread 34 and the lower thread 54 in the thread cutting device will be described. 1 to 4, the movable blade 64 is schematically shown, the feed dog 16 is omitted in FIGS. 2 to 4, and the needle insertion hole 18 is provided.
Only shown. First, after the loop 60 of the upper thread 34 is captured by the capturing beak 50, the movable blade 64 is advanced, and the upper thread 34 and the lower thread 54 are separated by the thread separating section 86, and the movable blade 6 is moved.
When the bobbin thread 4 is retracted, the lower thread 54 is caught by the first thread hooking portion 76 and the thread loop 60 of the upper thread 34 is caught by the second thread hooking portion 78 as shown in FIG. Along with that, the needle side portion 112 of the yarn wheel 60 is captured by the protruding portion 58 of the outer shuttle 46. In this state, the needle side portion 112 of the yarn wheel 60 is located in the clearance groove 82 of the movable blade 64, while
No. 0 cloth side portion 114 and the bobbin thread 54 cloth side portion 116 have grooves 7
Located within 0. Then, the needle side portion 11 of the thread wheel 60.
2 is captured in the notch 96 of the movable blade 64. As shown in FIG. 2, as the movable blade 64 moves backward, the notch 96 pulls the needle side portion 112 of the yarn wheel 60, so that the yarn wheel 60 surely moves.
8 and continues to be caught by the needle side 112 of the thread wheel 60 and the bobbin thread 54.
Is separated from the base end portion 118.

When the movable blade 64 is further retracted, the pressing surface 108 of the pressing member 106 is moved to the movable blade 6 as shown in FIG.
4 is located in the vicinity of both thread hooking portions 76, 78 and
Since the lower thread 54 is pressed from the 0 side, the lower thread 54 is held by the pressing portion 108 and the lower surface 80 of the movable blade 64. Since the needle side portion 112 of the upper thread 34 is housed in the relief groove 82, even if the upper thread 34 is thicker than the lower thread 54, the thickness of the upper thread 34 does not hinder the holding of the lower thread 54, 54 is securely held. The cutting edge 102 of the fixed blade 100 and the cutting edge 94 of the movable blade 64 cut the cloth side portion 114 of the yarn wheel 60 and the cloth side portion 116 of the bobbin thread 54. Both threads 34,
Since the cloth side portions 114 and 116 of 54 are positioned in the groove 70 of the movable blade 64, only the portion to be cut is the cutting blade 94.
To prevent the other part from coming into contact with the cutting blade 94 and being cut or damaged.

As the movable blade 64 moves backward, the pressing member 10
The pressing surface 108 of No. 6 slides in contact with the lower surface 80 of the movable blade 64, but the needle side portion 112 of the needle thread 34 is escape groove 82.
Since it is housed inside, the pressing member 106 does not move the lower thread 54 in a direction approaching the base end portion 118.

The state after cutting is shown in FIG. After cutting,
The needle side portion 112 of the upper thread 34 is pulled out by a wiper device (not shown) and is raised together with the needle 24. The needle side portion 112 of the upper thread 34 is not brought close to the lower thread 54 as described above, and the second thread hooking portion 78 to the base end portion 11 of the lower thread 54 is not used.
Since it extends in a direction different from 8 and is completely separated from the lower thread 54, it is possible to favorably prevent the lower thread 54 from being pulled out together with the upper thread 34 being pulled out. Further, since the needle side portion 112 is housed in the escape groove 82, the pressing of the lower thread 54 by the pressing member 106 is not hindered when the needle thread 112 is pulled out, and the proximal end portion 118 of the lower thread 54 is pressed by the pressing member 106.
It is satisfactorily held between the pressing surface 108 and the lower surface 80 of the movable blade 64. Therefore, the first stitch can be reliably formed when the next sewing is performed.

In this embodiment, the notch 9 of the movable blade 64
6 catches and pulls the needle side portion 112 of the yarn wheel 60,
The yarn wheel 60 continues to be reliably caught by the protrusion 58 of the outer hook 46,
It is avoided that the thread loop 60 is disengaged from the protrusion 58 and the upper thread 34 and the lower thread 54 are not sufficiently separated from each other and cutting is performed. In addition, the needle side portion 112 after cutting has a sufficient length,
Due to insufficient length of the upper thread 34 when the needle 24 is raised, the upper thread 34
Is prevented from coming off from the needle hole 32.

In this embodiment, the movable blade 64 also serves as a thread hooking member, but a thread hooking member having first and second thread hooking portions and a clearance groove may be provided separately from the movable blade. Is. It is also possible to provide the escape groove in the pressing member. In addition, the present invention is applied in various modifications and improvements based on the knowledge of those skilled in the art, such as applying the present invention to a sewing machine having a thread catcher having an outer hook rotatable about a horizontal axis. Can be implemented.

[Brief description of drawings]

FIG. 1 is a plan view schematically showing a yarn cutting device according to an embodiment of the present invention and its periphery.

FIG. 2 is a plan view showing a state different from that of FIG. 1 of the device.

FIG. 3 is a plan view showing the state of the above apparatus different from those in FIGS. 1 and 2.

FIG. 4 is a plan view showing the state of the above apparatus different from those in FIGS. 1 to 3;

FIG. 5 is a front cross-sectional view showing a part of a sewing machine including the above device.

FIG. 6 is a plan view showing a member having both a thread hooking member and a cutting means of the above device.

FIG. 7 is a front view (partial cross section) of the member of FIG.

FIG. 8 is a plan view schematically showing a conventional yarn cutting device and its periphery.

[Explanation of symbols]

 10 Bed Part 34 Upper Thread 42 Thread Cutting Device 54 Lower Thread 64 Movable Blade 76 First Thread Hooking Part 78 Second Thread Hooking Part 82 Escape Groove 100 Fixed Blade 106 Pressing Member

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masami Ito 15-1 Naeiro-cho, Mizuho-ku, Nagoya-shi Brother Industries, Ltd. (72) Inventor Yoichi Kumanda 15-1 Nae-shiro-cho, Mizuho-ku, Nagoya-shi Brother Industrial Co., Ltd. Within the corporation

Claims (1)

[Claims] 1. A thread hooking member provided movably with respect to a machine frame of a sewing machine and having a thread hooking portion for catching a lower thread and an upper thread, and a lower thread and an upper thread caught by the thread hooking member. And yarn cutting means for dividing the lower thread and the upper thread caught by the thread hooking member, and the lower thread cut by the cutting means. In a thread cutting device of a sewing machine including a pressing member that presses and holds the thread hooking portion, the thread hooking portion is divided into a first thread hooking portion that catches a lower thread and a second thread hooking portion that catches an upper thread. The relief grooves are provided at different positions of the member, and at least one of the thread hooking member and the pressing member has an escape groove at a position where the upper thread separated from the lower thread by the thread dividing means extends from the second thread hooking portion. Thread cutting of sewing machine characterized by being formed Location.