JPH03133485A - Thread insertion device of sewing machine - Google Patents

Abstract

PURPOSE:To sufficiently absorb the slack of a thread and to dispense with a moving mechanism for a thread holding part by providing the thread holding part at a link point approaching and separating from a supporting shaft at a side opposite to a sewing needle, and keeping tension between the thread holding part and a thread connecting part. CONSTITUTION:A presser pan 36 is provided at a link pin 34 approaching/ separating from a thread insertion bar 3 at the side opposite to a needle bar 2, and the change of a gap between the presser pan 36 and the thread connecting part 50 can be obtained widely by keeping the tension between them, which enables the slack of the thread T to be sufficiently absorbed. Also, it is not required to provide a mechanism for the movement of the presser pan 36 additionally. Also, when the thread T is introduced to the hook part of a hook 5, the thread T further bites in the direction of the link pin 34, and it is held more solidly, therefore, the introduction of the thread can be surely performed. Meanwhile, when the thread T is captured and extracted, the presser pan 36 approaches the thread insertion bar 3, and also, the thread connecting part 50 is separated from the sewing needle 11, and the thread T is relaxed, which enables the thread T to be easily extracted.

Description

[Detailed description of the invention] Purpose of suction [Industrial application field] The present invention relates to a threading device for a sewing machine, and more specifically, a threading device for a sewing machine that threads thread through the eye of a sewing needle in preparation for sewing with a sewing machine. Regarding.

[Prior Art] Conventionally, threading devices for sewing machines have been equipped with a support shaft that is provided parallel to the needle bar and is rotatable and can be raised and lowered, and a threading hook (hereinafter simply referred to as the hook) that projects from the support shaft. ), the support shaft is lowered so that the heights of the hook and the eye of the sewing needle are equal, and then the hook is inserted into the eye of the sewing needle by rotating the support shaft, and the thread is stretched in front of the eye. capture,
It is known that after catching the thread, the hook is pulled out of the eye of the sewing needle by reverse rotation of the support shaft while loosening the thread, and the thread is threaded through the eye of the sewing needle. In such a threading device, the operation of tensioning the thread in front of the eye of the sewing needle is performed by applying a matched thread from the thread supply source to the thread hook provided on the support shaft, and
The end of the thread is pulled with a finger to make the thread taut as it is guided to the eye of the sewing needle and captured by the hook, and when the hook is pulled out, the thread is loosened to the extent that it does not come off the hook.

This type of finger operation requires a certain amount of experience, as it is difficult to guide the thread into the eye of the sewing needle and how to time the tension/relaxation of the thread. Therefore, in place of such manual operations, the applicant of the present application has filed a technology for tensioning and relaxing the thread in front of the eye of the sewing needle in conjunction with the movement of the hook (Japanese Patent Laid-Open No. 63-89194). ). The threading device shown in this technique has two thread locking members rotatably protruded from and removed from a support shaft, and when the hook approaches the eye hole of the sewing needle, the distance between the two thread locking members is widened. and a mechanism that narrows the distance between the two thread locking members when the hook moves away from the eye of the sewing needle, and the thread is inserted into the slit formed in both the thread locking members to tension the thread in front of the eye of the sewing needle. The thread is tensioned and relaxed in conjunction with the hook by the action of guiding the thread and the action of relaxing the thread.

[Problems to be Solved by the Invention] Although the threading device described above is excellent in that it eliminates human factors by providing means for tensioning and relaxing the thread, it has the following problems. In other words, this threading device tensions the thread when the hook is retracting, but the thread does not come out smoothly from the slit in the thread locking member on the end of the thread, and the thread is pulled by the thread during the retracting action of the hook. Otherwise, the thread may come off the hook too quickly and you may not be able to pull the thread out from the eye of the sewing needle for a long time.L If you increase the width of the slit, the thread will come out smoothly, but the thread will be strained. Sometimes there is not enough tension and the thread is not properly captured by the hook. In this way, in the action of tensioning and relaxing the thread, it is not possible to obtain thread tension suitable for each action.

In addition, since both image members rotate around the axis of the support shaft, it is not possible to make a large change in the distance between both image members, and it is difficult to absorb slack in the thread between both stop members and on the yarn supply source side. This problem can be solved by moving the L5 locking members far away from the support shaft, but the connecting member connecting the support shaft and both image members is This increases the length and requires a large space to rotate this connecting member around the support shaft.

The threading device for a sewing machine of the present invention solves the above-mentioned problems, applies appropriate tension to the thread according to the catching operation of the hook, and threads the thread into the eye of the sewing needle in a satisfactory manner.

The structure of the present invention that achieves the above object will be explained below.

[Means for Solving the Problems] The needle hole system threading device of the sewing machine of the present invention is formed to be movable forward and backward with respect to the eye of the sewing needle, and includes: a threading hook that captures the thread; a support shaft that controls the approach action of approaching and penetrating the eye of the sewing needle, and the retraction action of retracting from the eye of the sewing needle; and a tag that is rotatably supported on the support shaft; the distance from the support shaft to the sewing needle; A yarn locking portion that is slightly longer and protrudes in the radial direction of the shaft and locks the yarn supplied from the yarn supply source near its tip; a link mechanism that brings the locking portion close to the eye of the sewing needle and moves the thread locking portion away from the eye of the sewing needle when the hook is retracted; In a threading device for a sewing machine that threads the thread by passing it through the eye of the sewing needle while catching the thread locked in the locking part, the link mechanism includes a threader on the opposite side of the sewing needle across the support shaft. A thread gripping part for gripping the thread is provided at a link point that moves away from the support shaft when the hook approaches and approaches the support shaft when the hook retreats, and the thread is stopped by the thread locking part. The end of the sewing needle is gripped by the thread gripping section, and the thread tension adjusting means is configured to tension the thread near the eye of the sewing needle when the hook approaches the sewing needle, and relax the thread when the hook retreats. , the thread gripping section has two opposing plate surfaces, at least one of which is biased so as to press against each other, and a plate surface support section that pivotally supports the biased plate surfaces so as to be slidable in the pressure contact direction. In addition, at least one of the two plate surfaces has a groove on the outside of the plate support at a position where the thread inserted between the two plate surfaces is gripped during the approach operation of the hook. The gist is that it has been formed.

[Function] The threading device of the sewing machine of the present invention having the above configuration locks the thread supplied from the thread supply source in the thread locking portion, while the thread end side of the thread is gripped by the thread gripping portion. When the hook approaches in conjunction with the rotation of the support shaft, the thread tension adjusting means uses the link mechanism to move the thread locking portion closer to the eye of the sewing needle, and also moves the thread gripping portion on the link point away from the support shaft. Move the thread away from the needle, and tension the thread between the thread locking part and the thread gripping part near the eye of the sewing needle.

When the hook is retracted, the thread tension adjusting means uses the link mechanism to move the thread locking portion away from the eye of the sewing needle, and also brings the thread gripping portion closer to the support shaft, thereby increasing the tension between the thread locking portion and the thread gripping portion. Relax the thread. Thus, when the hook captures the thread, the thread is under tension, and when the thread is withdrawn from the sewing needle, the thread is relaxed. The thread gripping part presses the thread with two opposing plate surfaces when the hook approaches, and the thread is pulled by the hook when the hook retreats, so the thread gripping part is attached to the outside of the plate supporting part that pivotally supports these plate surfaces. Remove the thread and introduce it into the trench. The thread introduced into the groove is less pressed against the plate surface, and is pulled along with the hook's movement without interfering with the retracting movement of the hook.

[Example] In order to further clarify the structure and operation of the present invention described above, preferred embodiments of the threading device for a sewing machine according to the present invention will be described below.

FIG. 1 is an explanatory view showing the operation of essential parts of a threading device (hereinafter simply referred to as threading device) of a sewing machine as an embodiment, and FIG. 2 is a perspective view of the threading device; Figure 3 is its front view. Incidentally, FIG. 1 corresponds to the X-X arrow view in FIG. 3.

The threading device is parallel to a needle bar 2 which is vertically movably inserted through and supported by a needle bar base fixed to a sewing machine frame (not shown), and which is parallel to a needle bar 2 which is vertically movably inserted and supported by a needle bar base fixed to a sewing machine frame (not shown). Prepare the Tossho 3. A hook holding part 4 made of hard synthetic resin is fixed to the lower end of the threading bar 3. As shown in FIG. 1, the hook holding portion 4 has a threading hook 5 (hereinafter simply referred to as hook 5) that extends horizontally (parallel to the sewing machine bed (not shown)) and bends at a substantially right angle. A hook portion 9 is attached, which consists of hook guards 6.7 located on both sides and a yarn holding wire 8 extending horizontally as well.

The hook 5 is formed to be able to be inserted into the eye hole 12 of the hook 5 (as shown in Table 4, the hook portion of the hook extending downward at the tip of the hook [O is the sewing needle]). A yarn clamping wire 8 is in contact with the inner side of the hand, and the yarn clamping wire 8 is urged toward the tip of the hook 5 due to its elasticity.Hook guards 6.7 located on both sides of the hook 5 An rVJ-shaped thread introducing groove 13 is formed at the tip, and a wire sliding groove 14 in which the threading wire 8 can slide is formed at the deepest position of the thread introducing groove 13.

The hook holding part 4 is integrally formed with a protruding piece 5 extending in the opposite direction to the hook part 9. A through hole 6 is perpendicularly formed at the tip of this protruding piece 5, and two thread guide pieces 17 and 18 are formed to protrude horizontally.

At the lower end of the threading rod 3, a hook holding portion 4 is further attached.
A link lever 19 is inserted into the link lever 19, which is sandwiched vertically in the shape of a letter so as to be rotatable with respect to the threading rod 3, and a pin 20 projects vertically from the horizontally extending end of the link lever 19. It is set up.

Furthermore, a thread locking portion 50 is fixed to the U-shaped back surface of the link lever 19.

As shown in FIG.
Fixed plate 21 fixed to the back of 9 and fixed plate 2]
Arm 2 that protrudes horizontally from the lower end and has a curved central part
2.23, a presser pawl 24 extending downward from the tip of the arm 22 in the protruding direction, and a thread catch pawl 25 extending upward from the tip of the arm 23 in the protruding direction, and these are integrally formed. has been done. The tip of the presser claw 24 is connected to the fixing plate 2.
], and a groove 26 is formed in the thread hook at the starting position of the curve.

In the threading bar 3, at the upper part of the hook holding part 4, a sliding guide 29 is sandwiched between two E-rings 27 and 28 fitted into the threading bar 3, and protrudes in the opposite direction of the needle bar 2, and is loosely inserted. The E-rings 27 and 28 regulate the vertical position. Furthermore, a support frame 31 is integrally formed on this sliding guide 29 and has a groove 30 formed in the axial direction parallel to the upper system passing rod 3 . The pin 32 is loosely fitted. Therefore, when the threading rod 3 moves up and down, the sliding guide 29 and the support frame 31 also move up and down together, but do not follow the rotation of the shaft of the threading rod 3.

A guide groove 33 of a required length is bored in the sliding guide 29, and a link pin 34 forming a link mechanism is slidably fitted into the guide groove 33.

This link pin 34 pivotally supports a link plate 37, which is supported by a link plate 35° presser plate 369 and a plate holder, which will be described later. As shown in FIG. 1(A), the link plate 35 has through holes 3 bored at both ends.
8.39, the link pin 34 and the pin 20 protruding from the link lever 9 are rotatably inserted into each other. In addition, the link plate 37 of the counter plate supported by the link pin 34 is
A thread guide piece 40 is protruded from the side where the thread is supported, and a through hole 41 is bored at the other end. And this through hole 41 and
A through hole 1 bored at the tip of the protruding piece of the hook holding part 4] 5
6 is rotatably inserted through the pin 42.

In this way, the link plate 35 and the plate support that are commonly supported by the link pin 34 are connected to the link plate 37 and this link plate 3.
5 via a pin 20, and the plate support is a protruding piece that is connected to the link plate 37 via a pin 42]
5 constitutes a link mechanism.

In this link mechanism, a press plate 36 is slidably supported by a link pin 34 between a link plate 35 and a plate holder, and a link plate 37. As shown in FIG. 6, the holding plate 36 has a contact surface 43 that contacts the link plate 37;
The plate support is biased toward the link plate 37 by the coil spring 44. A thread removal groove 45 is recessed in the link plate 37 of the plate holder at a position facing the contact surface 43 of the presser plate 36 and a predetermined distance away from the link pin 34 along the thread path.

Next, the operation of the threading rod 3 will be explained. For details of the mechanism governing this operation, please refer to the applicant's Jikko 6
It is described in Japanese Patent No. 1-35188.

Threading rod 31 OK By operating the operation lever (not shown),
The hook 5 and the eye of the sewing needle 1 attached to the needle bar 2 are lowered a predetermined distance to a position where the horizontal position of the eye 2 is equal, and then rotated by a predetermined angle in the direction of arrow a in FIG. 1(A). do.

Due to this rotation, the hook portion 9 rotates integrally around the axis of the threading rod 3, and the hook 5 penetrates into the eye hole 12 of the sewing needle 1 and stops. Next, when the operating lever is released, the threading rod 3 rotates in the opposite direction in the direction of the arrow, the hook portion 9 rotates in the opposite direction, and the hook 5 comes out of the eyelet 12 of the sewing needle 11.

After the threading rod 3 has been rotated by a predetermined angle, it is raised to the initial position.

Threading device (Yo) Due to the operation of threading device 3,
When the hook 5 penetrates the eye hole 2 of the sewing needle 1, the thread T is stretched in front of the eye hole 12, and the hook 5 captures the thread T, and when the hook 5 exits the eye hole 2, Threading is performed by relaxing the thread T captured by the hook 5 and pulling it out, and the operation is as follows.

FIG. 1(A), FIG. 2, and FIG. 3 show the initial state before starting the threading operation. Sewing machine user (sideways)
Prepare the yarn T supplied from the yarn supply source in the following order. First, the thread T is hung on the needle bar thread guide 46, and the thread hook is introduced from the outside of the claw 25 to the inside of the presser claw 24. Subsequently, the thread T is hung on the lower surface of the thread guide piece 17[deg.]8, the presser plate 36 and the plate holder are inserted between the link plate 37, and pulled toward the link pin 34. This operation is performed in a series of operations by running the thread T along a thread preparation path groove 48 formed in a face plate 47 attached to the head of the sewing machine. Then, to complete the preparation operation, the thread T is cut by the cutter 49 provided at the end point of the thread preparation path groove 48. At this time,
As shown in FIG. 6(A), the thread T is attached to the link board 37.
The thread guide piece 4ot is introduced in the direction of arrow A, and is inserted and held closer to the link pin 34 than the thread removal groove 45, as shown in FIG.

After the thread T is prepared in this manner, the threading rod 3 is lowered by operating the operating lever and further rotated in the direction of arrow a in FIG. 1(A). At this time, the hook part 9 and the protruding piece 5 fixed to the threading rod 3 rotate in the directions of arrows c and d in FIG.
The hook 5 of the hook portion 9 penetrates into the eye hole 12 of the sewing needle 11. As the protruding piece] 5 rotates, the link pin 34 loosely fitted into the guide groove 33 of the sliding guide 29 moves the plate holder via the link plate 37 in the direction of arrow e, that is, in the direction away from the threading bar 3. Then, the pin 20 is further moved in the direction of arrow f via the link plate 35. Therefore, the link lever 19
The thread locking portion 50 fixed to the back of the link lever 19 rotates in the direction of the arrow g and approaches the sewing needle 1].

That is, when the protruding piece 15 is rotated by the rotation of the threading rod 3, the movement is the same as that of the protruding piece] 5 - the plate holder connected via the pin 42 and the link plate 37 - the link connected via the link pin 34. The thread is transmitted in this order from the plate 35 to the link lever 19 connected via the pin 20, and the two thread locking portions 50 approach the sewing needle 11.

By such an operation, the thread T, whose one end is held by the presser plate 36, increases the distance between the presser plate 36 and the thread hook 25, so that the thread T therebetween is tensioned. At this time, due to the rotation of the thread locking part 50, the thread hook 25 slides toward the thread supply source side while maintaining the tension of the thread T with the presser plate 36, and the thread hook 25 slides toward the thread supply source side. Absorbs the slack of the T. When the thread T is further rotated and the thread hook 25 approaches the sewing needle, the thread hook is removed from the claw 25 and the thread hook of the presser claw 24 is introduced into the groove 26, and this thread hook is connected to the groove 26 and the presser foot. The thread T is tensioned with the plate 36 and guided in front of the eye hole 12 of the sewing needle 11 (the state shown in FIG. 1(A)). In this state, the hook 5 has penetrated into the eye hole 12 of the sewing needle 11, as shown in Figures 4(A) and 2, and the tensioned thread T is introduced into the inner side of the hook of the hook. At the same time, the sewing needle 11 pushes the thread clamping wire 8,
Connect the thread holding wire 8 to the wire sliding groove of the hook guard 6.7]
Slide it inside 4.

On the other hand, the thread T held between the presser plate 36, the plate holder, and the link plate 37 is moved by the presser plate 36 together with the link pin 34,
As the thread T moves away from the link pin 34, the thread T becomes tense and sinks in the direction of the link pin 34 (in the direction of the arrow B in FIG. 6(A)), and is firmly clamped. Therefore, the thread T is sufficiently tensioned between the presser plate 36 and the thread locking part 50, so that the thread T is introduced into the thread introduction groove 13 of the hook guard 6.7 and is inserted into the hook part of the hook 5. ]O is definitely captured.

Next, when the threading bar 3 is rotated twice in the direction indicated by the arrow in FIG. Therefore,
Each member constituting the link mechanism operates to return to the above-mentioned operation.

That is, the presser plate 36 pivotally supported by the link pin 34 moves in the direction of the arrow and approaches the threading rod 3, and the thread locking portion 5
0 rotates in the direction of arrow m and moves away from sewing needle 11. At this time, the thread hook of the thread locking part 50 is moved so that the thread Tli, which was locked in the groove 26, comes off from there and the tension is not released, and as shown in FIG. 4(A), the thread Tli is caught by the hook 5. The sewing needle 11 is then pulled out from the eye hole 12 of the sewing needle 11. This hook 5
By the pulling-out operation, the thread T is bent at the hook 10 of the hook 5, the slack in the thread T between the hook 10 and the presser plate 36 is absorbed, and the thread T becomes taut again. Furthermore, if the force in the direction of the arrow 1 in FIG. 1 (2) continues to act on the hook 5, the thread T gripped by the presser plate 36 loses the gripping force to the pulling force of the hook 5, and the thread T is pulled out as shown in FIG. 1 (2). (1) slide in the direction of the arrow n. When this sliding starts, the thread T will move as shown in FIG. , arrow C
direction, and falls into the thread removal groove 45 as shown in FIG. Therefore, the thread T is released from pressure from the presser plate 36 and slides in the thread removal groove 45 with less resistance, so that the tension of the thread T between the presser plate 36 and the hook portion 10 of the hook 5 is loosened. As the hook 5 is pulled out, the thread T is easily pulled out from the eye hole 12 of the sewing needle 11. Incidentally, even if the tension of the thread T is loosened, the thread T caught by the hook part 10 of the hook 5 is held by the thread clamping wire 8, so that the thread T is held by the hook part 10.
I can't get away from it.

Upper thread threader 31 When the reverse rotation of the predetermined angle is completed, the lifting operation begins. Due to this upward movement, the hook portion 9 and each member constituting the link mechanism rise together. At this time, the thread T caught by the hook portion 10 of the hook 5 is pulled up and roughly pulled out from the eye hole 12 as shown in Figure 4 (T); Due to the frictional force at 12, the weight of the thread T, etc., the hook 5 is no longer able to hold the thread T and comes off from the hook portion ]O.

The threading device of the sewing machine according to the present embodiment described above has the needle bar 2
A link pin 34 that approaches and separates the threading rod 3 on the opposite side of the
A presser plate 36 is provided at the trowel plate 36, and in order to tension the trowel thread T between the presser plate 36 and the thread locking portion 50, the gap between the two should be greatly changed.The slack of the thread T should be sufficiently absorbed. Can be done. Furthermore, there is no need to provide a special mechanism for moving the presser plate 36. Furthermore, when introducing the thread T into the hook portion 1o of the hook 5, the lower thread gripped by the presser plate 36 is
The thread T between the presser plate 36 and the thread locking part 50 can be sufficiently tensioned because it is further wedged in the direction of the link pin 34 and firmly gripped. The introduction into section 10 is ensured. On the other hand, when catching and pulling out the thread T, the presser plate 36 approaches the threading rod 3, the thread locking part 50 moves away from the sewing needle 11, and the thread T
However, the thread T can be easily pulled out. Even if the thread T is tensed again by pulling out the thread T, the thread T held between the presser plate 36 and the link plate 37 slides due to the pulling force of the hook 5, and the plate holder is attached to the link plate. 37, the tension on the thread T is released.
, the thread T can be easily pulled out. Further, since the lower part of the thread is held between the hook portions 0 of the hooks 5 by the thread holding wire 8, the thread T is prevented from coming off when the thread T is pulled out.

Furthermore, in the process of preparing the thread T for threading, since the thread T is held by the presser plate 36, the cutter 49 provided at the end of the thread preparation path groove 48 cuts the thread T into a predetermined position. Can be easily cut to length.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments in any way. 43, or the hook guard 6.7
．． Thread clamping wire 8. It goes without saying that it may be a simple configuration in which the cutter 49 and the like are omitted, and that it can be implemented in various forms without departing from the gist of the present invention.

Effects of the Invention As detailed above, according to the sewing machine threading device of the present invention, a thread gripping portion is provided at the link point that approaches and separates from the support shaft on the opposite side of the sewing needle, and the thread gripping portion and the thread Since the thread is tensioned between the thread and the stop, the slack in the thread can be fully absorbed by adjusting the distance between the two. Furthermore, there is no need to provide a special mechanism for moving the thread gripping section. Furthermore, when the thread is introduced into the hook, the thread held by the thread gripping part is further embedded in the direction of the plate support part, and is firmly gripped by the thread gripping part and the thread locking part. The thread between the hook and the hook can be sufficiently tensioned, and the thread can be reliably introduced into the hook. On the other hand, when the thread is captured and pulled out, the thread gripping portion approaches the support shaft and the thread locking portion moves away from the sewing needle, so that the thread is loosely knitted and the thread can be easily pulled out.

Even if the thread becomes tense again due to the thread being pulled out, the thread gripping section 2
The thread gripped by the two opposing plate surfaces slides due to the pulling force of the hook and falls into the groove provided in the plate surface, so the tension on the thread is released and the thread can be easily pulled out.

[Brief explanation of the drawing]

Figure 1 (A) is an explanatory diagram showing the operation of the main parts of the threading device of the sewing machine, Figure 2 is a perspective view of the threading device of the sewing machine, Figure 3 is its front view, and Figure 4 ( a) No shoes)
Figure 5 is a perspective view of the thread locking part, and Figures 6 (A) to 6) are explanatory diagrams showing the action of the thread gripped by the presser plate. 2... Needle bar 5... Threading hook] 2... Eye hole] 9... Link lever 35... Link plate 37... The counter plate is link plate 50... Thread locking part 3... Thread threader 11... Sewing needle 15... Projecting piece 34... Link pin 36... Presser plate 45... Thread removal groove T... Thread

Claims (1)

[Scope of Claims] 1. A threading hook that is formed to be movable forward and backward with respect to the eye hole of the sewing needle and that captures the thread; An approaching motion that supports the hook and causes the hook to approach and penetrate the eye hole of the sewing needle; a support shaft that controls the retraction operation of retracting the sewing needle from the eye hole; a thread locking portion that locks the thread supplied from the thread supply source; and a thread locking portion that moves the thread locking portion close to the eye of the sewing needle when the hook approaches in conjunction with the rotation of the support shaft; a link mechanism that moves the thread locking portion away from the eye hole of the sewing needle during a retracting operation of the sewing needle, and the thread locking portion is moved away from the eye of the sewing needle while the hook captures the thread locked in the thread locking portion by rotation of the support shaft. In a threading device for a sewing machine that threads the thread by inserting the thread through the eye hole of the sewing machine, the link mechanism includes a mechanism that moves away from the support shaft when the hook approaches the needle on the opposite side of the sewing needle across the support shaft, and A thread gripping part for gripping the thread is provided at a link point approaching the support shaft during the retracting operation of the hook, and the thread gripping part grips the end of the thread to be stopped by the thread locking part. A thread tension adjusting means is configured to tension the thread near the eye of the sewing needle during the approach operation of the sewing needle, and relax the thread when the hook retracts, and at least one of the thread gripping portions is biased so as to press against each other. and a plate surface support portion that pivotally supports the urged plate surface so as to be slidable in the pressing direction, and at least one of the two plate surfaces has the above-mentioned two plate surfaces. 1. A threading device for a sewing machine, characterized in that a groove is formed on the outside of the plate surface support at a position where the thread inserted between the two plate surfaces is gripped when the hook approaches the hook.