JPS5923832B2 - Needle thread adjustment device for sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a needle thread adjusting device for a sewing machine which combines a needle thread tension device and a balance device and is driven by a control motor.

Conventionally, as shown in the external view of the sewing machine in Figure 1, sewing machine 1
The needle thread 3 from the thread spool 2 stored in the thread spool 2 passes through the needle thread tension device 4, is turned back by the thread take-up spring guide 5, passes through the thread take-up device 6, and is guided to the needle thread.

That is, since the needle thread tensioning device 4 that applies tension to the needle thread 3 and the thread take-up device 6 for thread tightening and thread feeding are provided separately, the thread path becomes complicated and the threading of the needle thread 3 to the sewing machine 1 becomes difficult. It has the drawbacks that it is troublesome to put on and is not easy to use.

On the other hand, conventional balance devices have a link type balance with four
The ideal thread take-up trajectory could not be obtained due to the rotation of the links at the knots and 6 knots, and the upper thread sometimes became slack during sewing, resulting in skipped stitches and puckering.

In addition, with cam-type balances, an ideal trajectory can be obtained by forming a cam to absorb the slack in the upper thread, but this creates noise and applies excessive force to the balance, resulting in poor durability. There were drawbacks such as.

The present invention combines an upper thread tension device and a thread take-up device to form an upper thread adjustment device, which is driven by a dedicated control motor to apply tension to the upper thread and simultaneously tighten and unwind the thread. It is an object of the present invention to provide a needle thread adjustment device for a sewing machine that facilitates attachment of the needle thread to the sewing machine, prevents the needle thread from slacking during sewing, and enables optimal thread tightening and ideal thread unwinding. This is the purpose.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is an external perspective view of a sewing machine embodying the present invention.
The needle thread adjusting device 7 of the present invention is installed inside the sewing machine body 1, and the needle thread 3 from the thread spool 2 housed in the sewing machine body 1 passes through the needle thread adjusting device 7 and is guided to the needle. forming a road.

FIG. 3 is an external perspective view of the needle thread adjusting device of the present invention, and FIG. 4 is a side view showing the tension plate in section.

In the figure, 8 is a pulse control motor, a first tension plate 9 is fixed to the rotating shaft 8a, and a second tension plate 10 is loosely fitted to the rotating shaft 8a. An adjustment screw 11 is fixed to the tip of 8a, an adjustment knob 12 is screwed onto the adjustment screw 11, and a compression spring 13 is wound between the second tension plate 10 and the adjustment knob 12 to set the second tension. The plate 10 is brought into pressure contact with the first tension plate 9.

The first tension plate 9 has a substantially disk shape with one part protruding outward, and a plurality of guide rollers 14 are arranged and fixed at appropriate intervals on the circumferential edge of the first tension plate 9. A pair of conical thread pulling rollers 15 is fixed to the outside of the guide roller 14.

The second tension plate 10 has a protrusion 10a having approximately the same shape as the protrusion 9a of the first tension plate 9, and a circular portion having a smaller diameter than the first tension plate 9. A hole is formed into which the string pulling roller 15 and the guide roller 14 located inside the thread pulling roller 15 are inserted, and the circular portion is adapted to fit inside the remaining guide roller 14 of the first tension plate 9.

On the other hand, a presser foot lifter 16 related to a presser frame device (not shown)
An eccentric cam 18 is fixed to the rotating shaft 11 of the sewing machine, and a dish float lever 19 is swingably supported by a shaft pin 20 fixed to the sewing machine body in the vicinity of the eccentric cam 18. The lower end of the lever 19 is biased by the spring 21 to press the lower part of the dish lifting lever 19 against the eccentric cam 18, and the presser foot lifter 16
The dish lifting lever 19 is made to swing in conjunction with the operation.

An operating pin 22 is protruded from the upper end of the dish lifting lever 19. The operating pin 22 is inserted into a hole provided in the first tension plate 9, and the swinging of the dish lifting lever 19 moves the operating pin 22.
2 comes into contact with the second tension plate 10 and presses the second tension plate 10 against the compression spring 13 to separate it from the first tension plate 9.

Further, 23 is a stopper device, and the stopper device 2
Reference numeral 3 consists of a stopper lever 26 which is pivotally connected by a stopper shaft 25 to a stopper shaft 24 fixed to the sewing machine main body, and an adjustment selection panel 28 having a plurality of selection buttons 21 that engage with the stopper lever 26.

One end of the stopper lever 26 is bent into an L-shape and installed on the lower surface of the adjustment selection panel 28, and the other end is formed with a lock i26a that engages with the side surface of the adjustment knob 12. The spring 29 normally keeps the adjustment knob 12 and the locking surface 26a apart.

Then, by pressing any selection button 2γ,
The stopper lever 26 is swung against the spring 29 to bring the locking surface 26a into contact with the adjustment knob 12.
It is designed to restrict 0 rotation.

Further, the selection button 27 has a display LED and an electric contact inside, and is connected to the pulse motor control device 30, and transmits a signal corresponding to the pressed selection button 27 to the pulse motor control device 30, thereby Rotate the control motor 8.

. That is, by pressing the selection button 27, the adjustment knob 12 is prevented from rotating and the control motor 8 is driven to rotate the adjustment screw 11.
moves in the axial direction, thereby changing the spring force of the compression spring 13 and causing the second tension disc 10 to move towards the first tension disc 9.
The pressing force changes.

Here, the control device 30 is configured to determine the rotation direction and rotation amount of the control motor 8 according to the selection button 21 that is pressed.

A sensor is attached to the sewing machine to detect the type of thread, fabric, thickness of the thread, and thickness of the fabric, and the sensor's detection signal is input to the control device 30, and a predetermined program is used to select the optimum sewing machine. It is possible to obtain needle thread tension.

Next, to explain the operation with reference to Fig. 5, first, presser foot lifter 1
6 to open the first tenossion plate 9 and the second tension plate 1.
The needle thread 3 is installed between the first tension disc 9 and the second tension disc 100 with the tension disc 9 and the second tension disc 100 spaced apart from each other.

That is, by first bringing the needle thread 3 into contact with the thread-pulling roller 15, and then pushing the needle thread 3 inward, the needle thread 3 is passed over the thread-pulling roller 15, and is moved to the thread-pulling roller as shown by the broken line in FIG. 5A. 15 and the guide roller 14.

Subsequently, by lowering the presser foot lifter 16, the second tension plate 10 is brought into pressure contact with the first tension plate 9, and the upper thread 3 is held between both tension plates 9 and 10.

When the sewing machine starts to drive, the control device 30 rotates the control motor 8 in synchronization with the rotation of the sewing machine main shaft.
Tighten the thread and let out the thread.

That is, in FIG. 5B, the needle 31 is descending from the top dead center, the workpiece 32 is being fed, and here the tension plates 9, 1
0 is rotating clockwise and pulling up the upper thread 3.

In FIG. 5C, the tension plate 9° 10 rotates clockwise to the maximum angle position, the upper thread 3 is guided by the guide rollers 14 and wound up, and the upper thread 3 is pulled out by the inner hook 33.
The loop is tangled with the lower thread 34 and pulled up, thread tightening is performed, and the upper thread 3 is let out from the thread spool.

Subsequently, in the fifth diagram, the tension discs 9 and 10 are rotating counterclockwise to supply the needle thread 3 for forming a loop, and in the fifth diagram, the tension discs 9 and 10 are rotating counterclockwise to the maximum extent in the counterclockwise direction. It rotates to the angular position, supplies the needle thread 3 to be drawn out to the inner hook 33, and then changes to clockwise rotation and starts pulling up the needle thread 3.

Therefore, while the upper thread 3 is held between the tension discs 9 and 10 and tension is applied to it, the upper thread 3 is pulled up and tightened by the rotation of the tension discs 9 and 10, and the thread is let out from the thread spool.

The amount of pull or payout of the upper thread 3 is determined by the maximum rotation angle of the tension discs 9 and 10, and the upper thread 3 is optimally paid out by controlling the rotation of the control motor 8 in synchronization with the rotation of the main shaft of the sewing machine. And thread tightening can be performed.

As described above, according to the present invention, the control motor can prevent unnecessary slack in the upper thread, perform optimal thread tightening and thread unwinding, eliminate skipped thread breaks, and form beautiful seams. This also has the effect of making it easier to attach the upper thread to the sewing machine and improving usability.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the external appearance of a conventional sewing machine, Fig. 2 is a perspective view of the external appearance of a sewing machine embodying the present invention, Fig. 3 is a perspective view of the external appearance of the device of the present invention, and Fig. 4 is a cross-sectional view of the tension plate. The side view shown in FIG. 5 is an explanatory diagram of the operation. 1... Sewing machine body, 2... Thread spool, 3... Needle thread, 7
... Upper thread adjustment device, 8... Control motor, 9... First tension plate, 10... Second tension plate, 11.
... Adjustment screw, 12 ... Adjustment knob, 13 ... Compression spring, 14 ... Guide roller, 15 ... Thread pulling roller, 1
6... Presser foot lifter, 19... Dish lift lever, 23...
・Stopper device, 26...stopper lever, 27
...Selection button, 28...Adjustment selection panel, 30.
...Pulse motor control device, 31... Needle, 32...
Workpiece, 33... Inner hook, 34... Lower thread.

Claims (1)

[Claims] An upper thread tension device having 11 pairs of tension plates and a means for pressing the tension plates against each other is attached to a rotating shaft of a control motor that is driven in synchronization with the rotation of the main shaft of the sewing machine. Attaching the roller and clamping the upper thread with the tension plate to apply upper thread tension, and hooking the upper thread onto the thread pulling roller to perform thread tightening and thread unwinding by rotating the rotating shaft. An upper thread adjustment device for a sewing machine featuring: