JPH04141191A - Thread passing device of sewing machine - Google Patents

Abstract

PURPOSE:To enable a thread to be passed surely irrespective of the thickness of the thread and the kind and shape of a bobbin by providing a tensioning means for giving tension to the thread during sewing and a tension releasing means for giving no tension to the thread when the tensioning means is displaced to retreat from a position of a hook entering a needle hole. CONSTITUTION:A thread 47 drawn out of a bobbin 45 is guided to the thread passing mechanism 30 side through an untwisting pretension giving member 48 and a tension disc 49 of the tensioning means for example. The untwisting pretension giving member 48 is mounted to a support member 50 provided on a thread passing support frame 38. A like member 58 is pivotably supported by a shaft 59 caulked fixedly to the thread passing support frame 38. A thread loosening member 60 is pivotably supported by the shaft 59 and a hook part 60a formed in the intermediate left end of the thread loosening member 60 engages the left side part of the link member 58. Thus, the thread can be surely passed irrespective of the thickness of the thread and the kind, shape, etc., of a bobbin.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a threading device for a sewing machine that threads thread guided from a thread supply source through the eye of a sewing needle.

(Prior art) As an example of a threading device of a sewing machine, FIGS.
The configuration shown in FIG. 5 has been conventionally provided.

In FIG. 13, a needle bar 4 to which a sewing needle 3 is attached protrudes downward from the head 2, which is the left end of the arm 1 of the sewing machine. A support shaft 5 is provided in parallel and protrudes downward. The support shaft 5 is vertically movable and rotatable. A hook 6 for threading is provided at the lower end of the support shaft 5, as shown in FIGS. 14 and 15.

It is guided through the thread tension plate 10 and the guide 11 and stretched in front of the eye hole 3a of the sewing needle 3. Along with this, the operating lever 12
By moving the support shaft 5 downward, the support shaft 5 is moved downward and rotated in the direction of arrow A, and the hook 6 is inserted into the eye hole 3a of the sewing needle 3. This allows hook 6
Hook the thread 8 onto the hook portion 6a. After this, when the hand is released from the lever 12, the support shaft 5 is rotated in the opposite direction of arrow A and moved upward by a spring (not shown).

As a result, the hook 6 retreats from the eye hole 3a of the sewing needle 3 while catching the thread 8, and the thread 8 is thereby pulled out from the eye hole 3a and threaded as shown in FIG. 15. still,
Hook guards 13.13 are provided on both sides of the hook 6.

(Problems to be Solved by the Invention) In the above conventional configuration, when the diameter of the thread 8 is large, the loop of the thread 8 pulled out from the eye hole 3a of the sewing needle 3 may not be large enough. There were many. This is thought to be because when the hook 6 pulls out the thread 8 from the eye hole 3a, the thread 8 is not drawn out smoothly from the thread spool 7 side, so the thread 8 comes off from the hook 6. Since the thread 8 is guided from the thread spool 7 to the eye hole 3a through a number of guide tubes, passing resistance etc. overlap, and as a result, a large force is required to pull out the thick thread 8 from the thread spool 7 side. It's for a reason. Also, depending on the type and shape of the thread spool, the force required to pull the thread out of the thread spool may be large (sometimes). However, with such a configuration, when the hook is retracted from the eye hole, its retracting action becomes locked, and if it is forced to retract further, the hook may be damaged.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a threading device for a sewing machine that can reliably thread the thread regardless of the thickness of the thread and the type and shape of the thread spool.

[Structure of the Invention] (Means for Solving the Problems) A threading device for a sewing machine according to the present invention is a device for passing thread guided from a thread supply source through an eye of a sewing needle, a support member displaceable relative to the support member; and a threading hook provided on the support member that enters into and retreats from the eye of the sewing needle in response to displacement of the support member. A threading device for a sewing machine comprising: thread pulling means provided in the thread guiding path for drawing the thread to form a slack portion in the thread when the hook is displaced in the entry direction; A tension applying means is provided in a thread guiding path and applies tension to the thread during sewing, and when the tension applying means is displaced in a direction in which the hook enters into the eye hole in a retreating direction, tension is applied to the thread. It is characterized in that it is equipped with a tension release means that prevents the application of tension.

(Function) According to the above means, when the hook is displaced in the direction of entering the eye of the sewing needle, the thread is pulled by the thread pulling means to form a slack portion in the thread. Then, when the hook is displaced from the position where it entered the eye hole in the direction of retreating,
The tension release means prevents tension from being applied to the thread. For this reason, since there is a slack part in the thread and no tension is applied to the thread, the force required to pull out the thread is small, and when the hook moves back, the thread is pulled out smoothly and the thread does not come off the hook. . Therefore, threading can be performed reliably regardless of the thickness of the thread, the type, shape, etc. of the thread spool.

(Example) Hereinafter, Figures 1 to 10 will be explained regarding the first example of the present invention.
This will be explained with reference to the figures.

First, in FIG. 1, a needle bar 21 is supported by a needle bar support frame 22 so as to be movable up and down, and a sewing needle 23 is detachably attached to its lower end. The needle bar 21 is connected to the needle bar holder 24.
, is connected to an upper shaft 27 via a crank 25 and a counterweight 26. The upper shaft 27 is configured to be rotationally driven by a sewing machine motor (not shown), so that the needle bar 2
1, that is, the sewing needle 23 is driven in the vertical direction. Above needle bar 2
1, a positioning stopper 2 is located above the needle bar holder 24.
8 is screwed, and a stopper surface 28a is formed on the left side surface of this positioning stopper 28 in FIG.

The needle bar support frame 22 also includes a thread guide bar 29 (see Fig. 2).
is provided parallel to the needle bar 21, and the threading bar 29 is supported so as to be movable in the vertical direction and rotatable on its axis.

A threading mechanism 30 is provided at the lower end of the threading rod 29. An operating pin 31 is provided on the upper part of the threading rod 29 so as to protrude perpendicularly to the axial direction. This operating pin 3
1 is adapted to come into contact with a stopper surface 28a of the positioning stopper 28 when the threading rod 29 moves downward. A hollow operating rod 32 is slidably fitted into the upper part of the threading rod 29, and a compressed fill spring 33 is interposed between the operating rod 32 and the threading rod 29. There is. A substantially arc-shaped guide groove 328 directed upward is formed in the peripheral wall of the operating rod 32.
The operating pin 31 is engaged and guided within a. The operating rod 32 has a contact portion 32b at its upper end.
is provided protrudingly, and a hook portion 32c is provided protrusively from the intermediate portion. A coil spring 35 is provided between the hook portion 32c and a hook portion (not shown) provided on the movable table 34, and the actuation rod 32 is urged upward by the coil spring 35.

Further, a micro switch 36 is provided at the lower end of the operating rod 32.
is installed.

At the upper end of the needle bar support frame 22, a support shaft 3 having a hollow L-shape is provided.
One end of 7 is rotatably inserted and is prevented from being removed. The other end of the support shaft 37 is rotatably inserted into a threading support frame 38 fixed to a sewing machine frame (not shown) and is prevented from being removed. A guide rod 39 is fixed to the threading support frame 38 in parallel with the threading rod 29.
The movable table 34 is attached so as to be slidable in the vertical direction. A pin 40 is provided protruding from the guide rod 39, and by fitting this pin 40 into a groove 34a formed in the movable base 34, the movable base 34 is prevented from rotating. A protruding piece 34b that abuts the abutting part 32b of the operating rod 32 is formed at the upper end of the moving table 34, and an engaging shaft 41 protrudes toward the left in FIGS. 1 and 2. It is set up. Further, a rack portion 34c is formed on the rear side portion of the movable table 34, and a driving force transmission mechanism 42 is provided in this rack portion 34c.
The pinion gears 43 are in mesh with each other. The rotational force of a pulse motor 44 fixed to the threading support frame 38 is transmitted to the movable table 34 via the driving force transmission mechanism 42 . in this case,
When the pulse motor 44 is rotationally driven, the movable base 34 moves downward, and the projecting piece 34b of the movable base 34 engages the operating rod 32.
The actuating rod 32 is lowered by contacting the abutting portion 32b. By lowering the operating rod 32, the threading rod 29 is moved through the compression coil spring 33, the guide groove 328, and the operating pin 31, and the thread spool 45 is rotatably attached to a support shaft 46 fixed to the sewing machine frame. ing. The thread 47 led out from the thread spool 45 is passed through the threading mechanism 3 through the untwisted tensioning member 48 and the thread tension disc 49, which is a tensioning means.
You will be guided to the 0 side. Twisted back tensioning member 4
8 is attached to a support member 50 provided on the thread guide support frame 38. As shown in FIG. 3(a), the thread tension plate 49 is made up of two plate members 51 and 52, and the plate member 51 is pressed against the plate member 52 by a spring 53. A thread tension adjustment mechanism 54 (indicated by a two-dot chain line in FIG. 1) is provided to adjust the tension of the thread 47 by adjusting the spring force of the spring 53.

Here, a swinging member 55 is provided on the upper part of the threading support frame 38.
is rotatably provided by a screw 56 and a stepped collar 57. An engaging protrusion 55a formed at the lower end of the swinging member 55 in FIG. 3(a) engages with an engaging recess 58a formed in the link member 58. As shown in FIG. 1, the link member 58 is rotatably supported by a shaft 59 which is fixed to the threading support frame 38 by caulking. A thread loosening member 60 is rotatably supported on this shaft 59, and the thread loosening member 60 is shown in FIGS. 3(a) and 4(a).
A hook portion 60a formed at the middle left end portion is connected to the link member 5.
It engages with the left side of 8. The thread loosening actuating member 60 is formed with a cam groove 60b having an arcuate upper part and extending downward, and the engaging shaft portion 41 of the movable table 34 is fitted into this cam groove 60b (see FIG. 1). and FIG. 4(a)).

Further, at the end portion of the link member 58 in FIG. 4(a), a U
A character-shaped wire 61 is attached, and this wire 61
The engaging shaft portion 41 is fitted into the engaging shaft portion 41 .

On the other hand, one end portion of a thread securing wire 62, which is thread pulling means, for example, is rotatably connected to the upper part of the swinging member 55 on the side of the raw end in FIG. 3(a) by a caulking pin 63. The other end of the thread securing wire 62 is rotatably connected to the upper end of the thread loosening lever 64 by a step pin 65. The thread securing wire 62 is arranged so as to intersect with the guide path of the thread 47, and has a substantially U-shaped engagement portion 62a in the middle thereof.
is formed. 20 The thread 47 is disposed within the engaging portion 62a. The thread loosening lever 64 is rotatably provided with its lower end as a fulcrum, and is urged by a coil spring 66 to rotate in the direction of arrow B in FIG. 3(a). The thread loosening lever 64 is linked to the vertical movement of a presser bar (none of which is shown) to which a fabric presser is attached, and rotates in the opposite direction of arrow B when the presser bar is moved upward. It is supposed to be done. One end of the thread loosening actuating member 67 is engaged with the engagement recess 64g of the thread loosening lever 64. The other end of the thread loosening member 67 is connected to the plate member 51 of the thread tension plate 49. A tension release means 68 is constituted by the thread loosening lever 64 and the thread loosening operating member 67.

Now, the threading mechanism 30 mentioned above will be explained. The threading mechanism 30 includes a link mechanism 69 that stretches the thread 47 in front of the eye hole 23a of the sewing needle 23 as the threading bar 29 rotates in the direction of arrow C in FIG. The sewing needle 23 rotates together and enters the eye hole 23a of the sewing needle 23 and the eye hole 23a.
A threading hook 70 that is retracted from the inside is provided. The link mechanism 69 includes a first link 69a that rotates together with the threading rod 29, a second link 69b that is rotatably supported by the threading rod 29, and these first links 69a.
and a third link 69c provided between the second link 69b.
and a fourth link 69d. Connecting pin 71 connecting third link 69c and fourth link 69d
is a guide groove 72a (indicated by a two-dot chain line in FIG. (shown). A gripping member 73 that grips the end of the thread 47 is provided at the connecting portion between the third link 69c and the fourth link 69d. A hook stopper 74 is provided at the lower end in FIG. 6 of the second link 69b, and a thread holding portion 75 is provided at the lower end in FIG. 6 of the first link 69a. In this case, the thread 47 guided through the thread guide section 76 provided at the lower end of the needle bar 21 is stopped by the hooking stop section 74, and then held by the thread holding section 75, and further held by the thread holding section 75. Part 7
It is held by 3. Further, a mounting base 77 is provided at the end of the first link 69a on the threading bar 29 side, and the above-mentioned hook 70 and hook guard 78.
9 is fixed.

Hook guards 78 and 79 are arranged on both sides of the hook 70 at predetermined intervals. As shown in FIG. 5(a), the tip of the hook 70 is provided with a hook portion 70g on which the thread 47 is hooked.

The hook 70 enters into the eye hole 23a of the sewing needle 23, as shown in FIG. 5(c), when the threading rod 29 rotates in the direction of arrow C in FIG. As shown in FIG. 5(c) and FIG. 10, the hook guards 78 and 79 are formed with grooves 78a and 79a in the shape of a hollow.

On the other hand, as shown in FIG. 9, a coiled portion 80a of an elastic wire 80 is wound around the threading rod 29. As shown in FIG. One end 80b of the wire 80 is hung on the mounting base 77, and the other end 80c is hooked into the groove 7 of the hook guard 78, 79.
8a and 79a. The other end 80c and the hook portion 70a of the hook 70 are configured to hold the thread 47 hooked on the hook portion 70a. Further, as shown in FIGS. 6, 7, and 9, a regulating plate 81 is provided on the lower surface of the portion of the second link 69b that is closer to the threading rod 29. When the hook 70 enters the eye hole 23a of the sewing needle 23, the regulating plate 81 hits the other end 80c of the wire 80 and deforms it as shown by the two-dot chain line in FIG. 80c is prevented from hitting the sewing needle 23.

Next, the operation of the above configuration will be explained.

When threading the thread, first, the thread 47 from the thread spool 45 is untwisted and passed through the tensioning member 48 and the thread tension plate 49, and then passed through a thread take-up etc. (not shown) and then passed through the thread guide section 76. Further, the thread 47 is passed through a stopper 74 and a thread holder 75, and then held by a gripping member 73, and the end of the thread 47 is cut by a thread cutting blade 82 as shown in FIG. In this state, when an operating switch (not shown) for starting threading is operated, the pulse motor 44 is energized and rotated, and the movable table 34 and, in turn, the operating rod 32 move downward. This lowering of the operating rod 32 causes the threading rod 29 to move downward. In this case, when the engagement shaft 41 of the moving table 34 is lowered, as shown in FIGS. 3(a) and 4(a).
As shown in FIG. 4, since the engagement shaft 41 moves along the arcuate cam groove 60b of the thread loosening member 60, the thread loosening member 60 rotates in the direction indicated by the arrow in FIG. 4(a).

This rotation causes the link member 58 to rotate in the direction of arrow E in FIG. 4(a). As a result, the swinging member 55 rotates in the direction of arrow F in FIG. move. As a result, Figure 3(b)
As shown in FIG.
The tension is no longer applied to the thread 47.

When the threading rod 29 descends to the state shown in FIGS. 3(b) and 4(b), the operating pin 31 hits the stopper surface 2-8a of the positioning stopper 28. In this case, since the upper shaft 27 is stopped from rotating, the position of the needle bar 21 is also fixed, and further lowering of the threading bar 29 is restricted. In this restricted state, as shown in FIG. 5(b), the position of the eye hole 23a of the sewing needle 23 and the position of the hook 70 of the threading mechanism 30 are aligned. When the moving platform 34 is further lowered in the above-mentioned restricted state, the operating bin 31 is guided along the guide groove 32a of the operating rod 32, and the threading rod 29 is rotated in the direction of arrow C in FIG. do. At the same time, as shown in FIG. 4(b), the engaging shaft 41 of the movable table 34 is lowered in a state in which it is engaged with the wire 61 of the link member 58.

Due to this lowering of the engagement shaft 41, the link member 58 moves toward the arrow E.
At the same time, the swinging member 55 rotates in the direction of arrow F in FIG. Rotate in the direction of arrow G. As a result, as shown in FIG. 3(c), the engaging portion 62a of the yarn securing wire 62 traces the yarn 47 in the direction of arrow G to form a slack portion 47a.

On the other hand, by rotating the threading rod 29 in the direction of arrow C in FIG. 6, the link ai! The mechanism 69 rotates as shown in FIG. 7, and the thread 47 is stretched in front of the eye hole 23a of the sewing needle 23. At this time, as shown in FIG. 5(C), the hook 70 enters into the eye hole 2Ba of the sewing needle 23, and the hook portion 70a of the hook 70 hooks the thread 47. In this case, as shown in FIG. 9, the regulating plate 81 of the second link 69b is
By hitting the other end 80c of 0 and deforming it, the other end 80c is prevented from hitting the sartorial needle 23.

Then, until the hook 70 hooks the thread 47,
When the moving table 34 and the operating rod 32 descend, the microswitch 36 hits the contact portion 72b (see FIG. 2) provided at the upper end of the link guide member 72 and turns on. In response to this ON signal, the pulse motor 44 is driven in reverse, and the threading rod 29 is rotated in the opposite direction of arrow C in FIG. This rotation causes the hook 70 and the second link 69b to rotate in the direction in which they are separated, and as shown in FIG. 5(d), the hook 70
is retreated from the eye hole 2Ba of the sewing needle 23, and the second
The regulation plate 81 of the link 69b is connected to the other end 80c of the wire 80.
apart from the other end 80c and the hook portion 70 of the hook 70.
A thread 47 is held between the thread a and the thread a.

In this case, when the hook 70 retreats from the eye hole 23a of the sewing needle 23, the thread 47 is pulled out, but at this time, a slack portion 47a (see FIG. 3(C)) is formed in the thread 47. At the same time, as shown in FIG. 3(b), the thread tension plate 4
Since the plate member 51 of No. 9 is separated from the plate member 52 and no tension is applied to the thread 47, the force required to pull out the thread 47 is reduced. Therefore, unlike the conventional method (see FIGS. 13 to 15), the thickness of the thread 47 and the type of thread spool 45,
Regardless of the shape etc., when the hook 70 retreats, the thread 4
7 is pulled out smoothly. Therefore, the thread 47 is prevented from coming off the hook 70, and the return movement of the hook 70 is prevented from being locked.

Then, when the movable table 34 further rises to the initial state, the threading rod 29, that is, the hook 70 rises to the position shown in FIG. 5(e), and the thread 47 is pulled out for a long length.

According to this embodiment having such a configuration, the slack portion 4 is provided in the thread 47.
7g, and the plate member 51 of the thread tension disc 49 is separated from the plate member 52 so that no tension is applied to the thread 47. Even if the thread 47 is thick, the force required to pull out the thread 47 can be reduced. Therefore, conventionally (13th
15), the thread 47 can be pulled out smoothly when the hook 70 is retreated, regardless of the thickness of the thread 47 and the type and shape of the thread spool 45. Therefore, it is possible to prevent the thread 47 from coming off the hook 70 and to prevent the backward movement of the hook 70 from being locked, so that threading can be carried out reliably.

FIGS. 11 and 12 show a second embodiment of the present invention, and differences from the first embodiment will be explained. In this second embodiment, the swinging member 55 in the first embodiment,
Instead of providing the link member 58, the thread loosening member 60, the wire 61, etc., a solenoid 83 is provided on the upper part of the threading support frame 38, as shown in FIGS. 11 and 12.

A lever 84 is attached to the plunger 83a of this solenoid 83.
are connected, and the lever 84 has one end 84a
It is provided so that it can rotate using the side as a fulcrum. One end of a thread securing wire 85, which replaces the thread securing wire 62, is connected to the other end 84b of this lever 84. An engaging portion 85a having a cylindrical shape is formed in the middle portion of the thread securing wire 85, and the thread 47 is disposed within this engaging portion 85a. Further, in order to prevent tension from being applied to the thread 47 by rotating the thread loosening lever 64, a thread loosening solenoid (not shown) is provided.

According to the above configuration, for example, when the operation switch for starting threading is operated, the solenoid 83 is turned on and the thread securing wire 85 is moved to the right in FIG.
The thread 47 is pulled by the thread 5a, and a slack portion 47g is formed in the thread 47.
is formed. On the other hand, when the microswitch 36 is turned on and the pulse motor 44 is driven in reverse, the solenoid 83 is turned off and the yarn securing wire 85 is moved to the left in FIG. At this time, the thread loosening solenoid is simultaneously turned on and the thread loosening lever 64 is rotated, so that the plate member 51 of the thread tension plate 49 is separated from the plate member 52, and no tension is applied to the thread 47.

Therefore, in the second embodiment as well, substantially the same effects as in the first embodiment can be obtained.

In each of the above embodiments, the threading rod 29 is driven up and down by the pulse motor 44, but the invention is not limited to this. An operating lever is provided to drive the threading rod up and down, and the threading can be performed manually. You may also do this. Further, although the thread tension disc 49 is used as a tension applying means for applying tension to the thread 47, a roller-type thread feeding device, for example, may be used instead. In this case, the tension release means may have any structure as long as it prevents the roller from being pressed against the yarn. Furthermore, in each of the above embodiments, by setting the conditions such that the threading is performed with the presser bar to which the fabric presser is attached moved upward, the threading can be carried out.
In particular, it is possible to avoid applying tension to the thread when the hook is withdrawn from the eye of the sewing needle.

[Effects of the Invention] As is clear from the above description, the present invention includes a thread pulling means that is provided in the thread guiding path and that draws the thread to form a slack portion in the thread when the hook is displaced in the entering direction. , a tension applying means is provided in the thread guiding path and applies tension to the thread during sewing, and when the tension applying means is displaced from the position where the hook enters the eye hole in the direction of retreating, no tension is applied to the thread. Since the structure is equipped with a tension release means that does this, an excellent effect is achieved in that threading can be performed reliably regardless of the thickness of the thread, the type, shape, etc. of the thread spool.

[Brief explanation of the drawing]

1 to 10 show a first embodiment of the present invention, in which FIG. 1 is a perspective view of a threading device, FIG. 2 is an exploded perspective view of essential parts of the threading device, and FIG. 3 is a perspective view of a threading device. (a) or C) is a top view for explaining the operation around the thread securing wire, Figure 4 (a) or c) is a side view for explaining the operation around the thread loosening actuating member, and Figure 5 (a) , (b), (d), and (e) are longitudinal cross-sectional views for explaining the movement of the hook, FIG. 5(c) is a perspective view showing the state in which the hook has entered the eye of the sewing needle, and FIG. Figures 8 to 8 are cross-sectional views illustrating the operation of the hook and link mechanism, Figure 9 is an enlarged cross-sectional view showing the state in which the hook has entered the eye of the sewing needle, and Figure 10 is a side view of the area around the hook guard. It is. 11 and 12 show a second embodiment of the present invention, with FIG. 11 being a side view and FIG. 12 being a top view of the main parts. 13 to 15 show the conventional structure, in which FIG. 13 is a perspective view of the sewing machine head, FIG. 14 is a perspective view showing the state in which the hook has entered the eye of the sewing needle, and FIG. 15 is a perspective view of the sewing machine head. The figure is a perspective view showing a state in which a thread is passed through the eye of the sewing needle. 49 is a thread tension disc (tension applying means), 62 is a thread securing wire (thread pulling means), 68 is a tension releasing means, and 70 is a hook.

Claims (1)

[Claims] 1. A device for passing thread guided from a thread supply source through an eye of a sewing needle, the device comprising a support member displaceable relative to the sewing needle, and a support member disposed on the support member capable of displacing the support member. In the threading device of the sewing machine, the threading device includes a threading hook that enters into and retreats from the eyelet of the sewing needle in accordance with the threading direction, the hook being provided in the thread guiding path and retracting from the eyelet of the sewing needle. a thread pulling means that drags the thread to form a slack portion in the thread when the thread is displaced; a tension applying means provided in the guide path of the thread and applying tension to the thread during sewing; A threading device for a sewing machine, comprising a tension release means for not applying tension to the thread when the hook is displaced in a retreating direction from the position where the hook enters the eye hole.