JPS5949823B2 - Needle thread supply device for lockstitch sewing machine - Google Patents

Description

Detailed Description of the Invention This invention is based on the selection operation of the operating body provided on the outside of the machine frame, so that the intertwined part of the upper thread and the lower thread can be set in the middle (standard stitch) on the right bank, and if the part is missing (in the upper part) Needle thread supply of a lockstitch sewing machine in which the amount of needle thread fed out from the needle thread supply source to the thread take-up is automatically controlled in relation to the right bank and the feed pitch so that the needle thread is located at the lower side (sewing) or lower (hanging stitch) Regarding equipment.

2. Generally speaking, normal sewing is a standard stitch, but overstitching for buttonholes requires overhanging stitches, and basting requires overhanging stitching.

Conventionally, in order to obtain good stitches for each of the above, the tension adjustment of the upper and lower threads was performed using the upper thread tension device and each thread tension spring of the lower thread bobbin case in accordance with each condition such as the feed pitch and right bank. This was done individually by adjusting the spring pressure, but this adjustment required skill and was very complicated to operate.

This invention detects the right bank and feed pitch, calculates an appropriate amount of thread to be fed based on these, and pays out the upper thread amount from the supply source side to the thread take-up for each stitch according to the calculated results. By controlling the action of the limiter, the above-mentioned drawbacks of the conventional method can be eliminated, and by simply selecting and operating the operating member, a predetermined standard stitch can be sewn.
The purpose is to enable top hanging stitching and top hanging stitching.

Embodiments of the present invention will be described below with reference to FIG.

Reference numeral 1 designates a known lockstitch sewing machine, which includes a needle bar 3 that supports a needle 2 at the lower end and moves up and down, and a thread take-up 4 that moves up and down in synchronization with the needle bar 3 (it may also move back and forth laterally). ing.

Reference numeral 5 denotes a first thread tension device placed on the needle thread path between the needle thread bobbin (not shown) as a supply source of the needle thread 6 and the thread take-up lever 4, which applies a weak tension to the needle thread 6 to prevent it from being disturbed. Grant.

Reference numeral 7 denotes a thread feeding repulley placed on the upper thread path between the first thread tension device 5 and the thread take-up lever 4, around which the upper thread 6 is wound once.
The rotation is controlled clockwise in the figure by a driving means (hereinafter referred to as a motor) 8 such as a servo motor or a step motor.

Reference numeral 9 denotes a payout light absorption spring for absorbing slack in the upper thread 6 between the upper thread guide 10 and the thread feeding lip IJ7, and it always has a weak elastic force in the clockwise direction in the figure.

Reference numeral 11 denotes a second thread tension device disposed on the needle thread path between the needle thread guide 10 and the thread take-up lever 4, which controls the needle thread 6 so as to apply a tension to the needle thread 6 that is weaker than the tension applied to the bobbin thread. The spring pressure that presses the known thread tension plate held therebetween is made weaker than that normally used in the past, and together with the thread feed reprift, it constitutes a payout limiter.

12 is the upper thread 6 between the upper thread guide 13 and the second thread tension device 11.
It is a thread take-up spring to absorb the slack of the thread, and it always has a weak elastic force in the clockwise direction in the figure.

Next, the block diagram shown in FIG. 2 will be explained.

The microcomputer (hereinafter referred to as "microcomputer") 14 is a known one having functions such as storage, calculation, input/output, etc., and has input sections including a heavy weight detector 15, a cloth feed pitch detector 16, a sewing speed detector 17, an encoder 27, and an input section. The operating body 18 is connected, and the motor 8 is connected to the output section via a motor drive circuit 19.
Connect.

The thickness detector 15 corresponds to the thickness of the cloth W to be sewn (the thickness of two cloths when two cloths are sewn).

This device generates a frost thickness signal, and may be one that detects a change in electrical resistance due to the vertical movement of a known presser foot that supports the lower end of the presser foot.

The cloth feed pitch detector 16 generates a feed pitch signal corresponding to the cloth feed pitch, and is used to set the feed pitch.

It may be a device that detects a change in electrical resistance due to a rotational operation of a known feed adjustment dial.

The sewing speed detector 17 is a known device that detects the rotation period of the main shaft, and generates a sewing speed signal corresponding to the rotation speed.

The encoder 27 was fixed to the main shaft. The slit on the disk is detected and a spindle position signal is generated every rotation of the spindle.

The operating body 18 is movable and lockable in three positions with respect to the front wall of the machine frame of the sewing machine 1, and when each mark A, B, C matches the pointer 20, different stitch signals are generated. It happens.

The details of the microcomputer 14 will be described in the explanation of the operation below.

Next, this effect will be explained.

First, when the mark "A" on the operating body 18 is aligned with the pointer 20, the "standard stitch" program stored in the microcomputer 14 is selected.

Next, when the cloth W is set under the presser foot from this state, the frost thickness detector 15 outputs a frost thickness signal corresponding to the right bank (2d).

Further, the cloth feed pitch detector 16 outputs a feed pitch signal corresponding to the set feed pitch.

The right bank at this time is set to "2d", and the feed pitch is set to "2d".
P'', rP+2d in relation to the frost thickness signal and feed pitch signal.

The value of ; is calculated by the microcomputer 14.

Also, when sewing machine 1 is operated, the encoder 27 indicates that the main shaft is 1.
A spindle position signal is generated each time the spindle rotates, and a sewing speed signal is also generated from the sewing speed detector 17. Every time this spindle position signal is generated, the motor 8 is activated by the microcomputer 14 before the needle thread take-up action by the thread take-up is completed. In response to the command, the sewing machine operates at a speed proportional to the sewing speed, and rotates the thread feed reprift clockwise in FIG.

As a result, the needle thread 6 is fed out from the needle thread bobbin (supply source) to the second thread tension device 11□ side at a rate of rP+2dl for each stitch.

As mentioned above, while the needle thread 6 is being paid out, the slack in the needle thread 6 is absorbed by the paying-out thread sucker 9.

Therefore, since the tension of the upper thread 6 intertwined with the lower thread is weaker than the tension of the lower thread while the thread take-up 4 is rising, the rP+ absorbed by the payout light absorption spring 9 as the thread take-up 4 rises.
The upper thread 6 with a length of 2 dJ is fed out from the second thread tension device 11 to the thread take-up lever 4 side, and at first it is in the suspended state as shown in Fig. 4, but the upper thread with a length of rP + 2 dJ After the upper thread 6 is fed out to the thread take-up lever 4 side, the thread feed pulley 7 is controlled by the motor 8, and the upper thread 6 is no longer transferred from the supply source to the second thread thread take-up.
Since it is not fed out to the thread take-up lever 4 side via the thread tension device 11, as the thread take-up 4 approaches the top dead center, the tension of the upper thread 6 gradually becomes stronger than the tension of the lower thread, which prevents the two threads from becoming entangled. While tightening the bow I, move to the center of the fabric W (if sewing two pieces of fabric, the center of the right bank of all of them) and move to the fourth part.
Good standard stitches as shown in Figure A are formed.

Furthermore, when the symbol r B of the operating body 18 is aligned with the pointer 20, the "upper hanging stitch" program stored in the microcomputer 14 is selected.

゛In this case, the value of "P" is calculated by the microcomputer 14 in relation to the frost thickness signal and the feed pitch signal, and when the sewing machine 1 is operated, the upper thread 6 is calculated in relation to the sewing speed signal as described above. From the upper thread bobbin, thread the second thread at the rate of “P” every stitch
The rotation of the thread feed reprift is controlled via the motor 8 so that it is fed out to the thread tension device 11 side.

Therefore, in this case, the intertwining S of both threads is exposed on the cloth W, and a good overhang stitch is formed as shown in the opening in FIG. 4 where the upper thread 6 crosses straight.

Also, when the mark "C" on the operating body 18 is aligned with the pointer 20, the "upper hanging stitch" program stored in the microcomputer 14 is selected.

In this case, the value rP+4dl is calculated by the microcomputer 14 in relation to the right bank signal and the feed pitch signal, and when the sewing machine 1 is operated, the needle thread 6 is supplied from the supply source to 1 dl in relation to the sewing speed signal as described above. The thread feed reprift is rotationally controlled via the motor 8 so that it is fed out to the second thread tension device 11 side at a rate of IP+4 dJ for each stitch.

Therefore, in this case, the intertwined portion S of both threads is exposed under the cloth W, and a good overhang stitch as shown in FIG. 4C, in which the upper thread 6 crosses straight, is formed.

As described above, according to the present invention, in relation to the feed pitch and the right bank, the intertwined part of the upper thread and the lower thread is located directly in the right bank, or above or below the right bank in relation to the selected position of the operating body. In addition to calculating the amount of needle thread required for one stitch, the needle thread is fed out to the thread take-up at the rate determined by the calculation result for each stitch in relation to the sewing speed. By simply operating the machine, you can select standard stitches, top-hanging stitches, and top-hanging stitches, and you can automatically form good seams without having to adjust the conventional spring pressure for each stitch. It is something.

In the above embodiment, the motor 8 feeds out the upper thread 6 from the supply source to the second thread tension device 11 via the thread feed pulley 7, and the amount of the upper thread 6 is absorbed by the feeding light absorption spring 9.
When the thread take-up lever 4 rises, it is fed out to the thread take-up lever 4 side via the second thread tension device 11 (as well as the feed-out limiter). As shown in the figure, a feed-out limiter is provided with a pair of plates 22 for gripping and releasing the needle thread 6 by an electromagnet 21, and an operating body 18 is provided.
tl, t2. at the beginning of Figure 3, respectively, in connection with aligning the marks "rA, B, c" with the guideline 20. The upper thread grip may be released at time t3.

Reference numeral 23 denotes an optical encoder, which is composed of a slit disk 24 having slits arranged at equal intervals, a pair of light emitters 25 and a light receiver 26, which are arranged opposite to each other across the slits of the slit disk 24. The rotation angle of the slit disk 24 is detected in relation to the rotation of the slit disk 24 in conjunction with the rotation of the plate 22 due to the thread 6 being fed out, and based on this, the thread 6 is actually fed out for each stitch. The microcomputer 14 calculates the needle thread length calculated using the microcomputer 14, and compares this value with the required needle thread length for each stitch, which was calculated in relation to the feed pitch signal and the right bank signal, and performs the calculations described above based on this. The timing of energizing and de-energizing the electromagnet 20 is controlled by the microcomputer 14 so that the upper thread 6 is paid out as expected.

[Brief explanation of the drawing]

Figure 1 is a front view showing part of the sewing machine head, Figure 2 is a block diagram of the electric circuit, Figure 3 A is a diagram showing the thread take-up characteristics of the thread take-up, and the opening of the figure is an enlarged view of the part. Figures 4A and 4C are explanatory diagrams of each stitch showing standard stitching, top hanging stitch, and top hanging stitch in order, and Figure 5 is another embodiment of the feeding limiter.

Claims (1)

[Scope of Claims] 1. In a sewing machine that intertwines upper and lower threads through the cooperation of a needle, a hook, and a thread take-up that are linked to the main shaft, a feed dog that is linked to the main shaft moves along the top surface of the bed while protruding from the top of the bed. A cloth feed pitch detector 16 detects the distance and generates a feed pitch signal corresponding to the distance, and a cloth feed pitch detector 16 detects the floating distance of the presser foot from the top surface of the bed due to the object to be sewn and generates a right bank signal corresponding to the distance. a right bank detector 15; and a pay-out limiter 7 which is disposed on the needle thread path between the thread take-up and the needle thread supply source and is capable of acting on the needle thread to allow and prevent the needle thread from being fed from the supply source to the thread take-up. , an operating body 18 that can be moved and locked in three positions by manual operation, and an intertwined part of the upper thread and lower thread that is located at the center of the right bank, or above or below it, corresponding to each position of the operating body. In this way, the amount of needle thread required for one stitch is calculated in relation to the feed pitch signal and the right bank signal, and the feed-out limiter is operated to allow the amount of needle thread to be fed out during the period in which the needle thread take-up action is performed by the thread take-up. A needle thread supply device for a lockstitch sewing machine, comprising a control device 14 for controlling.