JPS6211491A - Needle thread supply control in sewing machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] B) Purpose of the Invention (Field of Industrial Application) The present invention forcibly threads the needle thread of the length required for stitch formation without using a thread take-up. This invention relates to a method for controlling upper thread supply in a sewing machine, in which the upper thread is supplied by a needle thread pay-out mechanism, and a thread take-up only performs a cloth tightening action.

<Prior art> In conventional sewing machines, when the needle thread of the length required for stitch formation is supplied to the thread take-up side by a forced needle thread feeder,
The needle thread is fed out by a rotating main shaft of the sewing machine or by a feeding device driven by a motor that rotates in synchronization with the main shaft of the sewing machine.

Therefore, in this type of sewing machine, (1) it is necessary to design the sewing machine itself in this way from the beginning, or to use a motor that rotates synchronously with the main shaft of the sewing machine to perform the needle thread unwinding operation. (11) Furthermore, it has been pointed out that there is a problem in that the length of the needle thread required for the -stitch changes as the number of revolutions of the main shaft of the sewing machine changes widely.

<Problems to be Solved by the Invention> Therefore, the present invention eliminates the need to design a unique sewing machine from the beginning as described above, and eliminates the need to use a special motor such as a synchronous or pulse motor. The present invention provides a needle thread supply control method that can be implemented by easily modifying a sewing machine, thereby ensuring that the needle thread of the length required for seam formation is always accurately supplied, regardless of whether the main shaft of the sewing machine rotates at high or low speed. The purpose is to make it possible to send out

(b) Structure of the invention and means for solving the problems> The present invention includes the following: (1) Seen from the supply side, the needle thread is passed in order between at least an electromagnetic needle thread gripping means, a needle thread pay-out roller that rotates at a constant rate regardless of the rotation of the sewing machine main shaft, and a presser roller that is lightly pressed against the same roller. The gripping means is released by detecting the end time of cloth tightening by the thread take-up, and the upper thread gripping means is released again in synchronization with the rotation of the upper thread feeding roller by a predetermined angle measured from that time. A method for controlling upper thread supply in a sewing machine, characterized in that the upper thread required for one stitch is supplied by closing the upper thread and pinching the upper thread.

(2) A second electromagnetic needle thread gripping means is provided between the needle thread pay-out roller and the thread take-up, and the second electromagnetic needle thread gripping means is used to hold the needle thread when the needle thread tension is generated due to passing over the hook, coming off the hook hook, or coming off the hook catching claw. grasp the
The needle thread supply control method for a sewing machine according to item (1) above, characterized in that the grip of the thread take-up is released before the time when the thread take-up starts to tighten the cloth.

It can be easily installed and used on regular sewing machines.
The needle thread payout amount does not fluctuate even with large changes in the rotational speed of the main shaft of the sewing machine, and the needle thread payout is not adversely affected by an increase in needle thread tension that occurs when the needle thread falls out of the hook. This method has been developed to control the needle thread supply.

<Function> A first) electromagnetic thread gripping means is provided, and the thread gripping means releases the gripping of the upper thread after the thread take-up finishes tightening the cloth, and uses the upper thread pay-out roller to hold the upper thread for a predetermined length of one stitch. Needle thread supply of 1
The thread gripping means is operated in synchronization with the corresponding rotation angle of the needle thread pay-out roller to grip the needle thread again and securely tighten the needle thread by one stitch in preparation for the next tightening using the thread take-up. The thread is fed, and preferably, a second electromagnetic needle thread holding means is further provided between the needle thread pay-out roller and the thread take-up, and this is used to control the needle thread tension change that occurs when the needle thread falls out of the hook. In order to avoid adversely affecting the needle thread supply mechanism, the needle thread is gripped at that time, and the grip is released during the time when the thread take-up is tightening the cloth, so that the needle thread for the first stitch is reliably fed to the thread take-up side. Configure. Note that the needle thread pay-out roller and presser roller always rotate at a constant rate regardless of the rotation of the sewing machine main shaft, but while the first thread gripping means is grasping the needle thread, the presser roller strongly presses the feed-out roller. Without pressure, the upper thread slips on the roller surface and the thread is not fed out.

In this way, since the needle thread pay-out roller is driven by a motor that rotates at a constant rate regardless of the rotation of the sewing machine main shaft, it is possible to ensure that a constant length is always maintained even when the sewing machine main shaft rotates at high or low speeds. The needle thread can be supplied to the thread take-up side, and this flexible needle thread supply control device can be provided separately from the sewing machine, so it is not only very convenient, but also can be used as a thread pay-out drive motor for each ridge type. You can choose to use a cheap one.

<Example> Fig. 1 is a perspective view of an embodiment of a sewing machine equipped with an upper thread supply control device that implements the method of the present invention, and Fig. 2 (a) and (b).
is an explanatory diagram showing the configuration of the upper thread supply control device shown in FIG. 1,
Figures 3 (al and b) show the encoder installed on the main shaft of the sewing machine, fa) is a side cross-sectional view, fb) is a front view of the slit disk, and Figure 4 is a cross-section of the electromagnetic upper thread gripping means. Figure 5 (a), fb), (C1 is a diagram showing the upper thread supply control state, (a) is the upper thread feeding, (b) and (C) are the high speed and low speed operation states of the sewing machine, respectively. FIG. 3 is an operation diagram of the electromagnetic upper thread gripping means in FIG.

FIG. 1 is a perspective view showing a sewing machine A equipped with a needle thread supply control device for carrying out the method of the present invention, and FIG.
As shown in al, a sewing needle 1, a thread take-up spring 3, a guide 4, 5, 6, a second electromagnetic upper thread gripping means 7, and a thread with an encoder driven by a motor that rotates independently of the main shaft of the sewing machine. A feed-out roller 8, a presser row 210 that is controlled to approach and separate from the feed-out roller 8 by an electromagnet 9, an electromagnetic needle thread gripping means 11 on the needle thread supply side (first), a base tension plate 2, a needle thread pobbin] 3 There is also a pulley 15 inside the sewing machine A as shown in Fig. 2 fb).
A rotary encoder 17 is provided on the main shaft 16 to which the rotary encoder 17 is attached. In addition, in the figure, 14 indicates a sewing thread, and B indicates an upper thread supply control device, and the paste tension plate 12 does not necessarily have to be included in this part.

This a-tally encoder 17 is used to detect the end time of tightening the cloth by the thread take-up, and a thread take-up position detector provided in a so-called electronic sewing machine may be used.

The upper thread 14 supplied from the upper thread bobbin 13 is given tension to the extent that the thread is not disturbed by the base tension plate 12, passes through the upper thread supply side electromagnetic upper thread gripping means 11 which is in a released state, and then is transferred to a constant rotation motor. The needle thread is held between an upper thread pay-out roller 8 with a drive encoder and a presser roller 10 and sent out to the thread take-up lever 4 side, and its pay-out amount is controlled by releasing the upper thread holding by the electromagnetic needle thread holding means 11. At the same time, the gripping of the upper thread by the feed roller 8 and the presser roller 1OVcL is strengthened, and the slippage between them becomes O, and the upper thread is fed out, and this state continues until the thread gripping means 11 returns to the closed state. It will be done. In other words, the needle thread payout amount t is
Setting this in advance determines the rotation angle of the upper thread unwinding roller from when the upper thread gripping means 11 releases the thread (assuming that no slippage occurs between the upper thread and the unwinding roller). If the rotation of the roller by a predetermined angle is detected and the upper thread gripping means 11 is returned to the closed state B based on the signal, the upper thread can be let out by a set length during that time.

When the gripping means 11 is in the closed state, the running of the upper thread is stopped;
A sliding action is caused between the thread pay-out roller 8 and the upper thread, and the thread pay-out roller 8 continues to rotate or the needle thread supply is stopped.

Note that when the electromagnetic upper thread gripping means 11 grips the upper thread, the electromagnet 9 moves the feed-out row 28 of the presser roller 10.
It is desirable to release the suppression of the thread so that it is not pinched.

The second electromagnetic thread gripping means 7, as shown in the frame 7M in FIGS. The thread take-up spring 3 is provided to absorb the increase in needle thread tension due to the change in needle thread tension (indicated by the curved line with three upward ridges) that occurs when the catching claw is removed. No, due to the hook structure, sewing conditions, etc., the increase in tension cannot be absorbed by the thread take-up spring 3 alone, and the thread take-up spring 3 is unable to absorb the increase in tension.
(as shown by the upper frame 7M), this change in tension exerts a tension on the upper thread that is being fed out while being clamped by the yarn feeding roller 8 (as shown by the frame 7M above), and this change in tension has an adverse effect on the thread feeding action by the thread feeding roller. This is to avoid giving.

Fig. 3 shows an example of a rotary encoder 17 installed inside a sewing machine, in which a casing 18 is provided surrounding a slit disc 21 fixed to the main shaft 16 of the sewing machine, and the slit disc 21 is attached to the inner wall of the casing. A light-emitting element 19 and a light-receiving element silver are provided, which are sandwiched and facing each other.
The end time of the cloth tightening action of the thread take-up by the main shaft 16, which rotates in synchronization with the operation of the thread take-up 2, is detected by a signal from a predetermined hole drilled in a specific part of the slit disc 21, and the first needle thread gripping means is actuated. Then, the upper thread grip is released, and the upper thread is let out by the constant rotation motor-driven encoder-equipped let-out roller 8. In addition, the signal releases the electromagnet 9 and presser foot row 21
0 is pressed against the feed-out row 28 to ensure that the upper thread is fed out.

FIG. 4 is a cross-sectional view showing the structure of the electromagnetic yarn gripping means 7 and 11, which includes a friction plate 5 provided on the upper surface of the coil bobbin 24 which is slidably fitted on a cylindrical yoke equipped with a magnet 22, and a friction plate 5 provided on the upper surface of the coil bobbin 24, The needle thread 14 is completely passed through between the cap-shaped body 26 and the back surface of the provided cap-shaped body 26, and by passing current through the coil 24, the needle thread 4 is clamped and the needle thread feeding by the feeding row 28 is stopped. Its operation is performed rapidly with almost no inertia by passing current through the coil bobbin 24. However, by pressing the friction plate 25 against the cap-shaped body 26, this part always holds the upper thread and releases the upper thread grip only when current is passed through the coil bobbin 24. It may be applied.

Next, the operation of the needle thread supply control device according to the present invention is illustrated in FIG.
) fb) This will be explained according to the diagram shown in (c). In addition, in the figure, time is adopted as the y-axis.

In the figures (b) and (c) (the y-axis indicates the magnitude of needle thread tension and the phase of the balance), A indicates the time when needle thread tension is generated due to the cloth tightening action of the thread take-up, and the opening indicates the time at the top dead center of the thread take-up. No. indicates the time when the needle thread tension disappears, and as shown in +a1 figure (y-axis (needer thread payout amount)), the needle thread is paid out by the needle thread payout row 28 with an encoder, which is driven by a motor that rotates at a constant rate. The first electromagnetic type on the needle thread supply side detects the point P [at the same time or a little later than in (b) and (C)] using a signal from the rotary encoder 17 installed on the main shaft of the sewing machine. The gripping of the upper thread by the thread gripping means 11 is released, the presser roller 10 is pressed by the upper thread letting-out roller 8, and the upper thread is let out. Needle thread length t
At the point of completion of feeding Q [(b) and (the second period in C1), the first electromagnetic needle thread gripping means 11 is operated again to grasp the needle thread, and the feeding action by the needle thread feeding roller 8 is stopped. At this time, if the pressure of the presser roller 10 and the feeding roller 8 is released, damage to the yarn due to friction with the roller surface will be reduced.

By the way, even though the sewing machine is capable of changing its rotational speed, the encoder-equipped needle thread pay-out roller 8 is configured to rotate at a constant rate, so that the same amount of needle thread is paid out in the same amount of time. Therefore, as shown in FIG. ) During high-speed and low-speed operation of the sewing machine, P
, the mutual relationship between the position of Q and the balance curve will change. Of course, the amount of upper thread t required for one stitch can be adjusted by changing the number of pulses on the encoder, but even when the sewing machine is running at high speed, the maximum amount required for that stitch can be adjusted. It is necessary to configure the supply so that it can be supplied between the time when the tension disappears due to the tightening action of the balance and the time when the ninth tension is generated. However, if we try to extend the period during which the upper thread can be supplied as long as possible, a tension generation phenomenon (indicated by the three chevron curves displayed in the frame 7M) will inevitably occur when the upper thread is removed from the hook. There is a risk that the needle thread payout control will be disturbed. For this reason, during such a tension generation period, that is, from near the bottom dead center of the thread takeup to before the cloth tightening tension is produced by the thread take-up, the second electromagnetic upper thread gripping means 7 provided on the take-up side side of the feed-out row 28 is used. (section 7M in the figure) to avoid applying any force to the feed-out roller 8 during the feed-out operation. The grip of the upper thread is released and the upper thread is let out between - and the thread take-up by the thread take-up roller 8, and at the same time, the cloth is tightened. Such a control signal can be easily obtained from the rotary encoder 17 provided on the main shaft, which rotates in synchronization with the operation of the thread take-up, which is strongly related to the generation of needle thread tension. In addition, (b) (C)
In the figure, IIM indicates the operating range of the first electromagnetic upper thread holding means 11, and 7M indicates the operating range of the second electromagnetic upper thread holding means 7. In this way, it is possible to perform sewing with good stitches even when the sewing machine is operated at high speed. In addition, if high-speed operation is possible, the case of low-speed operation is shown (
C) As shown in the figure, it is clear that at low speeds, it is possible to supply the required amount of upper thread to the -stitch without any problem.

FIG. 6 shows the results of the experiment No. 7, in which the test device described in the example was used, the needle thread 14 was cotton thread ≠ 80, the base tension was 2Of, and the delivery tension of the needle thread pay-out row 28 was 90F. Then, the weight is attached to the tip of the upper thread 14 that has passed through the guide 5.6,
Multiply by 7F to find the needle thread payout amount per 100 stitches (m/
m) and the spindle rotation speed (r, pom),
Each is plotted as an X mark. The diameter of the needle thread pay-out roller 8 of the test device is 40u1.The coaxial encoder is divided into 400 equal parts, and the total pay-out amount of one stitch is 1.
It was set to 0 pulse.

In the figure, the y-axis is the rotational speed (r, p, m) of the main shaft of the sewing machine, y
The axis is the amount of needle thread let out (m/m) under the above conditions.
), the length of 100 stitches is measured and displayed as an X mark. The table below shows the intensities of the currents applied to the first and second electromagnetic upper thread gripping means at this time.

According to the experimental results shown in this table, even though the rotational speed of the main shaft of the sewing machine was greatly changed, the amount of needle thread fed out was almost constant, and in practical terms it can be said that it is completely constant. I understand that there isn't. We were able to unexpectedly obtain data confirming the effects of the method of the present invention.

(c) Effects of the invention φ------ As explained above, in the method of the present invention, the end time of the cloth tightening action by the thread take-up is usually determined by a main shaft position detection device such as an encoder built into an electronic sewing machine. detect,
After that, an upper thread unwinding roller, which is driven at a constant rotation regardless of the rotation of the sewing machine, and a presser roller that comes in contact with the upper thread are operated to unwind the upper thread, and the amount of the upper thread is accurately controlled by the unwinding roller. Since this is done by stopping the upper thread running by gripping the electromagnetic upper thread gripping means provided on the supply side, it is not only possible to configure the upper thread supply control device as a separate unit unrelated to the sewing machine. , it is possible to always supply an accurate amount of upper thread for one stitch regardless of the rotational speed of the sewing machine, and the motor for this purpose does not need to have any special characteristics, allowing the use of inexpensive motors and constantly rotating. Because of this, there is no inertia change, making it fully compatible with high-speed operation.

Furthermore, if the encoder is integrated with the feeding roller, the pulses generated by the encoder are counted from the time when the electromagnetic needle thread holding device releases the needle thread holding, and when the required length of needle thread feeding is completed, the needle thread holding means The pulse oscillator causes the feed roller with a pulse motor driven by the pulse oscillator to count the pulses from the time when the upper thread grip is released, and after measuring a predetermined amount, removes the upper thread. Various configurations, such as a method for re-closing the gripping means, can be easily implemented.

Furthermore, by providing the second electromagnetic needle thread gripping means, the needle thread supply control mechanism is prevented from being affected by increased needle thread tension, which is a particular problem when removing the needle thread from the hook during high-speed operation of the sewing machine. Therefore, it is possible to obtain an upper thread supply control method that is fully applicable to high-speed sewing machines.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an embodiment of a sewing machine equipped with an upper thread supply control device that implements the method of the present invention, and FIG. 2 (al, (b))
is an explanatory diagram showing the configuration of the upper thread supply control device shown in FIG. 1,
and a schematic diagram of a pulley with a low-return encoder, Fig. 3 fa)
, (b) shows the encoder installed on the main shaft of the sewing machine, (a) is a side sectional view, (b) is a front view of the slit disk,
Figure 4 is a sectional view of the electromagnetic needle thread gripper, Figure 5 fa), f
b), (C1 is a diagram showing the upper thread supply control state, (a)
is upper thread feeding, [b) and fc) are operating diagrams of the electromagnetic upper thread gripper in high-speed and low-speed operating states of the sewing machine, respectively. Figure 6 shows the rotational speed of the main shaft of the sewing machine when the present invention is implemented. This is an example of test data showing the relationship between changes in needle thread payout amount. A...Sewing machine, B...Needle thread supply control device part, ■...Sewing needle, 2...Take-up lever, 3...Thread take-up spring, 4.5.6...Guide, 7... Take-up side electromagnetic upper thread gripper, 8...Thread feeding roller with motor-driven encoder, 9...
...Electromagnetic controller, 10...Press roller, 11...
・Needle thread supply side electromagnetic needle thread gripper, 12...Base tension plate, 13...Needle thread bobbin, I4...Needle thread, 15...Pulley, 16
...Main shaft, 17...Qp-1 coater, n...
Magnet, O... Cylindrical yoke, U... Coil bobbin, 5... Friction plate, 26... Cap-shaped body,
t...-Stitch needle thread amount, 7M...Take-up lever side electromagnetic needle thread gripper operating range, 11M...Needle thread supply side electromagnetic needle thread gripper operating range.

Claims (1)

[Scope of Claims] 1. Viewed from the supply side, the upper thread is moved between at least an electromagnetic upper thread gripping means, an upper thread unwinding roller that rotates at a constant rate regardless of the rotation of the sewing machine main shaft, and a presser roller that is lightly pressed against the same roller. The upper thread gripping means is released by detecting the end time of cloth tightening by the thread take-up, and is synchronized with the rotation of the upper thread feeding roller by a predetermined angle measured from that time. 1. A needle thread supply control method for a sewing machine, characterized in that the needle thread required for one stitch is supplied by closing the needle thread again and pinching the needle thread. 2. A second electromagnetic needle thread gripping means is provided between the needle thread pay-out roller and the thread take-up, and the second electromagnetic needle thread gripping means is used to grip the needle thread when the needle thread tension is generated due to passing through the hook, coming off the hook, or coming off the hook's catching claw. 2. The needle thread supply control method for a sewing machine according to claim 1, wherein control is performed to release the grip of the thread take-up before the time when the thread take-up starts tightening the cloth.