JPS6019277B2 - Sewing machine needle thread continuous feeding device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sewing machine that continuously feeds and feeds needle thread.

Conventionally, in a sewing machine, the needle thread of the length required for sewing one stitch is taken out from the needle thread bobbin via a thread tension disc using a thread take-up, or is taken out from the needle thread bobbin in an intermittent manner. Since the needle thread was forcibly supplied by the connecting mechanism, the movement of the needle thread was unstable during high-speed operation. The present invention improves this point by constantly supplying the upper thread,
This is intended to eliminate disturbances in needle thread supply during high-speed sewing operation. This will be explained below according to the drawings.

Figure 1 is a cross-sectional view when sewing two pieces of cloth together, and the needle thread length required when sewing two pieces of cloth with a thickness of d is the length when the upper and lower threads are intertwined in the middle of the two pieces of cloth. In the case of good stitching, if the stitch pitch is P, it becomes P+2d.
By the way, the needle thread take-up characteristic by the thread take-up is unique to each sewing machine and is as shown in Figure 2 A. If the needle thread is let out by P + phantom for each stitch, a good overall result as shown in FIG. 1 will be obtained. Conventionally, this has been done by balancing the needle thread tension and bobbin thread tension by adjusting the pressure of the needle thread tension disc and the thread tension spring in the bobbin case, or by adjusting the pressure of the needle thread tension spring in the needle thread tension disc and the lower thread bobbin case. Attempts were made to feed the length of P + phantom during the period when the thread was descending, and to have the thread tightened only using a thread take-up to ensure good results. On the other hand, in the present invention, as shown in FIG. 3, a first tension plate 2 applies a weak tension to the upper thread 1 from the upper thread bobbin (not shown) to prevent the thread from being disturbed. The yarn is wound around a servo motor controlled yarn feed pulley 3 provided with a V-shaped yarn winding groove through a tension bag (another suitable tension bag may be used), and a discharged yarn absorption spring 4 is provided on the side from which the yarn is fed out.
Furthermore, the second thread passes through the guide 5 and applies a tension weaker than that of the bobbin thread.
The thread is guided to the base tension plate 6 (a commonly used thread tension plate with a weakened pressure spring may be used), and from this it passes through the thread take-up spring 7, guide 8, and thread take-up lever 9, and connects it to the needle 101, as in the case of a secondary sewing machine. be.

Since the needle thread supply V direct feeder according to the present invention is configured as described above, the needle thread is fed at a rate of P+phantom for each stitch by the continuously rotating servo motor controlled thread feed pulley 3. It is supplied to the feed pulley 3 and the second base tension plate 6.

Since the slack of the yarn in this section is absorbed by the yarn absorption spring 4, no disturbance of the yarn occurs. Furthermore, since the tension of the upper thread intertwined with the lower thread is greater than the upper thread tension, the thread take-up 9 is in a hanging sewing state on the way up, but as the thread take-up approaches the top dead center, the second base tension increases. The upper thread is taken out from the disc 6, and by the time it reaches the top dead center, the thread of P + phantom length stored between the thread feed pulley 3 and the second base tension disc 6 by the thread absorption spring is removed. The balance 9 will be taken out. Furthermore, even if the thread take-up 9 attempts to take out a thread of P or more, since the thread feed pulley 3 is controlled by a servo motor, the rotation of the thread feed pulley 3 will not change even if the thread take-up action of the thread take-up takes place. , P+ can only produce lines. That is, since the lower thread tension is greater than the upper thread tension,
Due to the crossing force between the upper thread and the lower thread, only the p+ thread of the upper thread is let out. Therefore, the upper thread is always reliably supplied by the length P for each stitch, and a good stitch as shown in the first figure is performed. A control system when the present invention is applied to a sewing machine is shown as a block diagram in FIG.

That is, the thickness of the fabric to be sewn (phantom) is detected using the vertical fluctuation of the presser foot, and the fabric feed pitch p and sewing speed of the sewing machine are also sensed and stored in the computer, and the thread line output amount is calculated from this. , issues a servo motor rotation command, controls the rotation of the servo motor-controlled thread removal pulley 3, and controls P+ for each stitch.
Make sure to let out the needle thread to the desired length. Although the explanation was given assuming that the fabric thickness is 2d, even if the thickness of the upper and lower sewn fabrics is different, if the intersection point of the upper and lower threads is in the middle of the upper and lower sewn fabrics, the stitching will be good. The fabric thickness can be detected using the same machine as when we explained about stitching. Also, the second
The function of the base tension plate 6 is to hold the upper thread during the period when the thread take-up action is not performed by the thread take-up lever 9, and to hold the upper thread during the period when the thread take-up action is not performed by the thread take-up thread take-up, and to hold the upper thread during the period when the thread take-up action is not performed by the thread take-up thread take-up lever. The upper thread is held with a weak holding force that does not interfere, and the upper thread is continuously paid out by the servo motor controlled thread feed pulley 3, and the upper thread is stored between the thread feed pulley 3 and the second base tension by the thread absorption spring. Since it is a good thing, the second
In place of the base tension plate 6, an electromagnetically controlled needle thread gripper equipped with two plates for gripping and releasing the needle thread using electromagnets is used. The upper thread grip may be released at this time.

In this way, the needle thread that is continuously fed out by the thread feed pulley 3 is held between the needle thread gripper and the thread feed pulley 3, and the length of P used for the stitch is determined by the thread take-up 9. Since the upper thread grip by the riko electromagnet-controlled needle thread gripper is released at the time of starting the action of paying out the thread, the thread take-up 9 can be caused to pay out the needle thread stored by the thread absorbing spring 4. Note that if the needle thread gripper is used to firmly grasp the needle thread from the end of the thread take-up period to the above-mentioned period, the influence of tension fluctuations occurring on the needle thread on the needle side will be reduced during that period. The length of sewing thread required for one stitch can be reliably fed between the thread feed pulley 3 and the upper thread gripper (base tension plate 6) without being hit by the needle thread thread take-up. In some cases, by releasing the upper thread grip, the upper thread can be let out without applying much tension to the upper thread.

As explained above, according to the present invention, the necessary amount of upper thread is continuously supplied by the continuously rotating servo-controlled thread feed pulley, and the thread take-up only performs a thread tightening action to achieve good sewing. In addition, compared to conventional sewing machines equipped with a needle thread supplying device that repeatedly supplies and stops the needle thread, there is no inertia change, so the needle thread can be fed and fed smoothly and accurately even during high-speed operation. Furthermore, since there is no need to adjust the spring pressure of the thread tension as in conventional sewing machines, it is possible to always ensure good warping.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional diagram when sewing two pieces of cloth together;
Figure A is a diagram showing the thread take-up characteristics of the thread take-up; Figure 3 is a partially enlarged view; FIG. 4 is a block diagram showing the operation of the device of the present invention. 1... Upper thread, 2... First base tension device, 3
. . . Servo motor controlled yarn feed pulley, 4. Throw-off yarn absorption spring, 5. Guide, 6. Second base tension device or upper thread gripping release device, 7. Thread take-up spring, 8.
Guide, 9... Balance, 10... Needle. Figure 'Figure 2 Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. Between a first base tension device for applying a weak tension to the needle thread and a thread take-up, a continuously rotating servo motor-controlled needle thread pay-out pulley, a pay-out thread absorption spring, and a thread temporarily A second base tension device or an upper thread gripping/releasing device is provided for holding the thread in place, and the upper thread required for the first stitch is continuously fed out by the feeding pulley, and the thread tightening is performed by a thread take-up. Continuous needle thread feeding device for sewing machines. 2. A continuously rotating servo motor-controlled needle thread pay-out pulley and a pay-out thread absorption spring are provided between the first base tension device for applying a weak tension to the upper thread and the second tension device for providing a tension weaker than the bobbin thread. 2. The continuous sewing machine needle thread supply device according to claim 1, wherein the needle thread feeding pulley continuously supplies needle thread in an amount necessary for sewing with the sewing machine. 3 A continuously rotating servo motor-controlled upper thread is connected between a base tension device for applying weak tension to the upper thread and an upper thread gripping and releasing device for gripping and releasing the upper thread, which is installed on the upper thread supply side of the thread take-up. A feed-out pulley and a feed-out thread absorption spring are provided, and the needle thread feed pulley continuously supplies the amount of needle thread required for sewing by the sewing machine, and the needle thread is released by the needle thread gripping and releasing device at the time when the thread take-up starts to be fed out by the thread take-up. Claim 1: Releases the grip of the upper thread, and supplies the sewing thread required for one stitch stored between the upper thread payout pulley and the upper thread grip releaser.
Sewing machine upper thread continuous feeding device as described in .