JPH0630704B2 - Sewing machine thread pickup device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thread pickup device for a sewing machine.

2. Description of the Related Art Conventionally, as a thread pickup device of a sewing machine, a 4-bar linkage type thread pickup mechanism is generally adopted. However, in this thread pick-up mechanism, since it is a four-bar linkage type, it is not possible to obtain an ideal thread pick-up action, which causes a thread tightening failure of the seam. In particular, such a tendency is remarkable when the cloth is thick or when the cloth has thickened steps in the middle.

Therefore, the present invention aims to provide a thread take-up mechanism of a sewing machine which can always perform good thread tightening regardless of such variation in cloth thickness.

This means that a main thread take-up mechanism, a thread take-up spring that cooperates with the thread take-up mechanism, and an auxiliary thread take-up member that takes up the upper thread against the action of the thread take-up spring are provided. Is operated by interlocking with a presser bar to which a work clamp foot which cooperates with a four-moving feed dog is attached.

A sewing machine main shaft 2 is rotatably supported on a frame 1 of a sewing machine, and a uniform crank 3 is fixed to one end of the frame.
The needle bar 4 is supported by the frame 1 so as to be vertically movable, and the upper end thereof is connected to the equalizing crank 3 via a needle bar crank rod 5 and a needle 6 is attached to the lower end thereof.

One end of the main yarn pick-up lever 7 is rotatably connected to the equalizing crank 3, and the other end is provided with a yarn insertion hole 7a. The intermediate portion of the thread take-up lever 7 is rotatably supported by the other end of a link 8 whose one end is rotatably supported by the frame 1.

In the thread insertion hole 7a of the main thread take-up lever 7, a thread guide 9, a thread tensioner 10, a thread take-up spring 11,
A thread hooking portion and thread guide 12 of an auxiliary thread pick-up lever described later.
The upper thread 13 is supplied via the needle thread 13, and the upper thread 13 is guided from there through the thread guides 14 and 15 to the needle 6.

The thread tension device 10 includes a thread tension shaft 11 a fixed to the frame 1, a pair of thread tension discs 11 b, and a thread tension spring 1.
1c, the adjustment photograph 11d, the spring tray 11e, and the spring tray 11e, which is inserted into the thread tension shaft 11a and is pushed rightward in FIG. 2 when a manual presser foot lifting lever described later is operated. A thread tension pressure release pin 11f for moving the thread tension spring 11c against the action of the thread tension spring 11c to release the thread tension pressure from the thread tension disc 11b.

Further, the thread take-up spring 11 has a base end which is the thread tensioner 11
Of the main thread take-up lever 7 which is fixed to the thread tension shaft 11a of the 1 is actuated counterclockwise in FIG. 1 against its own elasticity by the tension of the upper thread 13 when the upper thread is picked up, and when the thread is fed by the main thread pick-up lever 7, the elasticity causes the clockwise direction in FIG. It returns and absorbs the looseness of the upper thread 13.

The presser bar 16 is supported by the frame 1 so as to be movable up and down, and cooperates with a feed dog 17 which makes a four-feeding motion at a lower end thereof to transport a work cloth 18 on a work cloth support surface 19 with a work foot 20. Is installed. A presser bar hanger 21 is fixed to the middle portion of the presser bar 16 with a set screw 22,
The presser bar hanger 21 is a guide groove 2 formed in the frame 1.
It is guided in the vertical direction by 3. A pressing pressure adjusting member 24 is screwed into the frame 1, and a cloth pressing coil spring 25 is provided between the pressing pressure adjusting member 24 and the pressing rod body 21. The support shaft 26 is rotatably supported by the frame 1, a manual presser foot lifting lever 27 is fixed at one end, and a presser foot lifting cam 28 is provided at the other end.
Is fixed.

At the lower end of the support plate 29, a pair of elongated holes 3 extending in the vertical direction is formed.
0 is formed, and a pair of set screws 31 passing through these slots 30
Thus, the support plate 29 is fixed to the frame 1. An intermediate portion of an auxiliary thread take-up lever 32 is rotatably supported on the support plate 29 by a step screw 33, and one end of the auxiliary thread take-up lever 32 is located outside the frame 1 and from the thread tensioner 10. It is configured as a thread hooking portion 32a extending on the upper thread path reaching the main thread pick-up lever 7.

The coil spring 34 is adjusted between a pin 35 screwed and fixed to the auxiliary thread pickup lever 32 and a bent portion 29a formed on the support plate 27, and the coil spring 34 is always attached to the auxiliary thread pickup lever 32 as shown in FIG. The counterclockwise turning force is applied. Further, an operating pin 36 is screwed and fixed to the holding rod body 21, and cam surfaces 32b and 32c which cooperate with the operating pin 36 are formed on the auxiliary thread pick-up lever 32. The cam surface 32b linearly extends in the lateral direction, and the cam surface 32c linearly extends in the vertical direction.

In the normal sewing state, the auxiliary thread take-up lever 32 is rotated counterclockwise in FIG. 2 by the coil spring 34, and its cam surface 32c is engaged with the operating pin 36 in the normal sewing state. It is in.

Now, considering the timing at which the main thread pick-up lever 7 is raised and the thread is picked up, at this time, the feed dog 17 is just in the process of rising on the work cloth supporting surface 19 (Fig. 4 shows the feed dog 17). The locus of one point at the upper end of the presser bar 16 is raised, and the presser bar 16 is lifted via the work cloth 18 and the presser foot 16 by the amount of the increase, whereby the presser bar hug 2
The auxiliary thread pickup lever 32 is rotated clockwise in FIG. 2 through the engagement between the operation pin 36 of No. 1 and the cam surface 32b. Therefore, since the upper thread of the needle 6 side of the thread tension adjuster 10 is consumed in this portion by the amount of the operation of the auxiliary thread take-up lever 32 downward, this results in promoting the thread take-up action of the main thread take-up lever 7. The thread tightening at the time of forming the stitch is performed well.

In this way, the thread tightening at the time of forming the stitch is performed. The degree of this thread tightening depends on the work cloth 18 to be sewn.
When the thicknesses of the yarns are different, the thicknesses are automatically changed, and a good thread tightening action is always performed. That is, when the thick work cloth 18 is sewn, the lifting amount of the presser bar 16 increases due to the increased thickness, and the auxiliary thread take-up lever 32 is additionally rotated in the clockwise direction in FIG. The thread take-up spring 11 is largely rotated counterclockwise in FIG. 1 against its elasticity. This means that the elastic return force of the thread take-up spring 11 acts on the upper thread 13 and the resistance applied to the upper thread 13 on the thread tensioner 10 side of the main thread take-up lever 7 increases, where When the main thread take-up lever 7 performs the thread take-up action, the upper thread 13 on the needle 6 side, which has less resistance to the thread, is easily pulled up, and thread tightening is performed well. Therefore, as the thickness of the cloth processing 18 increases, the upper thread 13 on the needle 6 side is pulled up more strongly, so that even when the processing cloths 18 having different thicknesses are used, constant thread tightening is possible.

Further, during sewing of the work cloth 18, when there is a step portion in the middle and the work cloth suddenly becomes thicker, the work presser foot 20 presses the work cloth more strongly than when sewing the work cloth of a constant thickness. (This means that when the sled portion at the tip of the thread presser foot 20 faces the step portion, the load applied to the work clamp foot 20 is temporarily applied to the step portion only through the sled portion. Therefore, the resistance of the work cloth at the time of thread tightening increases, and thread tightening becomes difficult. But,
As described above, at that time, the resistance of the thread take-up spring 11 increases with the operation of the auxiliary thread take-up lever 32,
Moreover, before and after the presser foot 20 is opposed to the stepped portion of the work cloth, the amount of yarn picked up by the auxiliary yarn pickup lever 28 is rapidly increased, so that thread tightening at the stepped portion is also improved.

The operation of the auxiliary thread pick-up lever 32 is performed within a range in which the operation pin 36 engages with the cam surface 32b.

After the sewing is completed, the presser bar 16 is lifted via the presser bar holder 21 by operating the manual presser foot lifting lever 27 and the work clamp foot 2
When 0 is raised, the operating pin 36 comes off the cam surface 32b and faces the cam surface 32c. Operating pin 3
When 6 engages with the gum surface 32c, its cam surface 32c is set to be parallel to the axis of the presser bar 16, so that even if the actuating pin 36 is raised, the auxiliary thread take-up lever 32 is It is not moved beyond the operating position by 32b and remains stopped at that operating position. This is to limit the operating range of the auxiliary thread pick-up lever 32 when the cloth presser is raised so that the upper thread 13 does not come out of the eye hole of the needle 6.

Effects As described in detail above, the present invention is directed to the main yarn pick-up mechanism (7, 8).
And the like), the auxiliary thread pick-up member (32) is provided to promote the thread pick-up operation when the thread pick-up operation is performed.
The thread tightness of the seam can be excellently achieved.

Moreover, since the auxiliary thread pick-up member (32) is configured to be interlocked with the presser bar (16) that rises in accordance with the four-feed motion of the feed dog, thread pick-up by the main thread pick-up mechanism (7, 8 etc.) When the thickness of the work cloth (10) is increased, for example, the presser bar (16) is lifted by the increased amount while the thread picking up action can be effectively promoted in synchronization with the timing. As a result, the yarn pulling action of the auxiliary yarn pulling member (32) is further promoted, and at the same time, the yarn pulling spring (11) is more strongly operated against its own elasticity, so that the main yarn pulling mechanism. The resistance to the upper thread (13) on the thread supply source side with respect to (7, 8 etc.) is increased, and the upper thread on the needle (6) side is easily pulled up. As a result, the work cloth (18) used is Good thread tightening regardless of thickness .

Further, when there is a stepped portion in the middle of sewing and the thickness of the work cloth suddenly increases, it becomes more difficult to pick up the upper thread for the reason described above. At this time, in addition to the increase in resistance due to the thread take-up spring (11), Immediately after facing the stepped portion, the yarn pick-up amount of the auxiliary yarn pick-up member (32) rapidly increases, so that the thread can be satisfactorily tightened even at the stepped portion.

[Brief description of drawings]

FIG. 1 is a front view, FIG. 2 is a left side view showing the upper plate in section with the face plate removed, FIG. 3 is a sectional view taken along line 3-3 of FIG. 2, and FIG. FIG. In the figure, 1 is a frame, 2 is a sewing machine spindle, 6 is a needle, 7 is a main thread take-up lever, 10 is a thread tension regulator, 12 is a presser bar, 1
3 is a feed dog, 14 is a presser foot, 15 is a cloth, 16 is a cloth supporting surface, 17 is a holding bar, 21 is a coil spring for cloth pressing,
5 is a support plate, 28 is an auxiliary thread pickup lever, 28b, 28
c is a cam surface, 30 is a coil spring, and 32 is an operating pin.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Bibliographic references Sho 52-74844 (JP, U) Japanese Patent Sho 45-15711 (JP, B1)

Claims (1)

[Claims] 1. A presser bar (16) movably supported on a frame (1) of a sewing machine and having a lower end provided with a cloth presser foot (20) cooperating with a feed dog (17) performing a four-feed motion.
And a thread tension device (1) movably supported on the frame (1).
0) from the needle to the needle, and the main thread take-up mechanism (7, 8 etc.) for taking up the thread of the upper thread (13), and the main thread take-up mechanism from the thread tensioner (10). (7,8
Etc.) and is operated against the elasticity of itself by the tension of the upper thread (13) during the thread pickup by the main thread pickup mechanism (7, 8 etc.) and the main thread pickup A thread take-up spring (11) that recovers by the elasticity of itself when the thread is supplied by a mechanism (7, 8 etc.) and absorbs the looseness of the upper thread (13), and the main thread take-up mechanism (7) from the thread tensioner (10). , 8
Auxiliary thread pick-up member (3) for movably supported by the frame (1) on the upper thread path leading to the upper thread (13) and for picking up the upper thread (13) against the elasticity of the thread take-up spring (11).
2) provided between the auxiliary thread pick-up member (32) and the presser bar (16), and interlocked with the lifting of the presser bar (16) accompanying the four-feed motion of the feed dog (17). And an operating means (21, 36, 32b, etc.) for operating the auxiliary thread pick-up member (32) to pick up the upper thread (13) against the elasticity of the thread take-up spring (11). Characteristic sewing machine thread pickup device.