JPH0213496A - Needle thread supply device for sewing machine - Google Patents

Abstract

PURPOSE:To enable an accurate supply motion to be carried out by directly restraining or releasing the rotation of a driving roller by a restraining means for feeding or stopping a needle thread, so that the occurrence of elongation and dislocation of the needle thread can be prevented. CONSTITUTION:A roller restraining means 39 for restraining or releasing the rotation of a driving roller 32 for feeding a needle thread is provided, and the driving roller 32 is connected to a drive shaft 25, which rotates with the drive of a sewing machine, by a frictional force. And in the restrained condition of the restraining means 39, the driving roller 32 is slid in relation to the drive shaft 25. At the same time, in the nonrestrained condition of the restraining means 39, the driving roller is integrally turned with the driving shaft. On the other hand, a detecting means 40 for detecting the amount of rotation of the driving roller 32 is provided. And it is so contrived that, in a nonrestrained condition, when the amount of rotation detected by the detecting means 40 reaches the amount of rotation equivalent to the required thread amount for one needle, the restraining means is brought into a restrained condition.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an automatic thread supply device for a sewing machine that feeds the amount of thread necessary for sewing each needle to the thread take-up side.

[Conventional technology]

Currently, sewing machines are equipped with a needle thread feeder that forcibly feeds the needle thread toward the thread take-up, depending on factors such as the right limit, the fabric feed pinch, and the needle swing distance.

Conventionally, as this type of device, those shown in FIGS. 6 and 7 have been proposed.

In this device, the needle thread 1 passes from the needle thread supply source 1 through the base tension plate 2, between the thread clamping portions 3a of the solenoid 3, and between the drive roller 4 and the driven roller 5.
A needle 9 is fixed to a needle bar 8 through a thread take-up spring 6 and a thread take-up lever 7.
sent to. The drive roller 4 has a pulley 10 and a concoder 1
A timing heald 15 is mounted between the pulley 10 and a sliding pulley 14 provided on the drive shaft 13.

As shown in FIG. 7, the drive shaft 13 has gears 16.about.17.
1.8.19 to the main shaft 20, and rotates at a ratio set by the gear group with respect to the rotation of the main shaft 20. Further, the sliding pulley 14 is attached to the drive shaft 13 as shown in FIG. 7. That is, the pulley 14 is slidably inserted into the drive shaft 13, and is pressed against a stopper member 22 provided on the same shaft 13 by the pressing force of a spring 21 inserted through the drive shaft 13, and the pulley 14 and the stopper member The drive shaft 13 rotates integrally with the drive shaft 13 due to the frictional force generated between the drive shaft 22 and the drive shaft 13. Therefore, when a rotation preventing force exceeding the frictional force is applied to the pulley 14, only the drive shaft 13 rotates while the pulley 14 remains prevented from rotating.

In such an automatic needle thread supply device, while the sewing machine is being driven, that is, while the main shaft 20 is rotating, the rotation of the main shaft 20 is always transmitted to the drive shaft 13 via the gears 16.17° and 18.19. If the solenoid 3 is now turned OFF and the upper thread ■ is released from being held, the rotation of the drive shaft 13 is transmitted to the rotation shaft 12 via the pulley 14, belt 15, and pulley 10, and thereby the drive roller 4 rotates,
Feeds out the amount of yarn in the direction of the thread take-up. Then, when the pulley 10 reaches a rotation amount corresponding to a preset feed pitch, the solenoid 3 is turned on, the upper thread I is clamped by the thread clamping portion 3a, and movement of the upper thread is stopped.

As a result, the rotation of the rollers 4 and 5 holding the upper thread I stops, and the rotation of the pulley 10 also stops. As a result, the drive shaft 1 is connected to the pulley 14 via the timing heald 15.
Drive shaft 1
3 all spin idly with respect to the pulley 14.

Thereafter, the thread take-up 7 pulls up the upper thread T in order to form the next stitch, and at the same time it begins to loosen the upper thread (2), the solenoid 3 is turned off and the above-mentioned upper thread feeding operation is started again.

In this way, in the conventional automatic needle thread supply device, the needle thread ■ is always urged toward the thread take-up by the roller 4.5, and the needle thread ■ is held and released by the solenoid 3. Since the needle thread is fed out and stopped, it has the advantage that better responsiveness can be obtained compared to a method in which the needle thread is fed out by intermittent feeding of a roller using a stepping motor.

[Problem to be solved by the invention]

However, in the above-mentioned conventional automatic upper thread supply device, after the upper thread has stopped being fed out, the rotational force of the drive roller 4 causes the
There was a problem in that the upper thread 1 was stretched between the solenoid 3 and the drive roller 4, and the upper thread 1 was unwound to the side of the thread take-up lever 6 by the amount of stretch, resulting in inaccurate unwinding. .

In addition, the upper thread 1 used varies in thickness and slipperiness, and depending on the type, even if the solenoid 3 is ONL, the upper thread τ is not firmly fixed, causing it to shift relative to the solenoid 3. However, this sometimes resulted in inaccurate delivery amounts.

This invention was made in view of the above-mentioned problems, and an object of the present invention is to provide an automatic needle thread feeding device for a sewing machine that can accurately feed each needle without causing the needle thread to stretch or shift. shall be.

[Means to be solved by the invention]

This invention restrains the rotation of the drive roller that sends out the upper thread.
A roller restraining means for releasing is provided, and the drive roller is connected by frictional force to a drive shaft that rotates with the driving of the sewing machine, and the drive roller is slid with respect to the drive shaft in a restrained state of the restraint means. , the drive roller is caused to rotate integrally with the drive shaft when the drive roller is not restrained by the restraint means, and a detection means for detecting the amount of rotation of the drive roller is provided, and the rotation detected by the detection means when the drive roller is not restrained is provided. The restraining means is placed in a restraining state when the amount of rotation reaches the amount of rotation corresponding to the amount of thread required for one stitch.

[For production]

In this invention, the restraining means directly restrains and releases the rotation of the drive roller to let out and stop the upper thread, so when the upper thread is stopped being pulled out, the upper thread is not pulled by the drive roller. Therefore, no elongation occurs in the upper thread.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, 23 is the main shaft that drives the needle bar and the thread take-up; 24
is the gear fixed to this main shaft 23, 25 is the machine frame M of the sewing machine
A gear 26 that meshes with the gear 24 is fixed to the drive shaft 25 . 2
7 is a first pulley rotatably inserted into the drive shaft 25;
Reference numeral 28 denotes a push spring inserted through the drive shaft 25. One end of the spring 28 is in contact with a spring receiver 29 fixed to the upper end of the drive shaft 25, and the other end is in contact with the inner surface of the first pulley 27. The lower surface of the first pulley 27 is brought into pressure contact with a stopper 30 fixed to the drive shaft 25. Reference numeral 31 denotes a rotating shaft rotatably supported by the machine frame of the sewing machine, and a driving roller 32, a second pulley 33, a roller plate 34, and a detection plate 35 are fixed to the rotating shaft 31, respectively. Reference numeral 36 denotes a driven roller that is pivoted to a mounting member 37 that is pivotally supported on the sewing machine frame, and this driven roller 36 is brought into pressure contact with the outer peripheral surface of the drive roller 32 by a spring (not shown). Further, among the driving roller 32 and the driven roller 36, the driving roller 32 is formed of a hard member (for example, metal, ceramic), etc., and has a knurling-like unevenness carved on its outer peripheral surface. Further, the driven roller 36 corresponding thereto is formed of a soft member such as rubber or synthetic resin.

38 is a timing heald installed between the first pulley 27 and the 21st pulley 33;
The rotation of the -ri 27 is transmitted to the 21st-ri 33. 39
is a solenoid which is controlled to be turned ON and OFF by a control means to be described later, and in the ON state, it clamps the peripheral edge of the rotating plate 34, and in the OFF state, it releases the clamping of the rotating plate 34.

Further, 40 is a photo ink club consisting of a light emitter/receiver arranged on the upper surface side and the lower surface side of the detection plate 35;
The number of pulses corresponding to the rotation amount of 5 is output. In addition, 41
is a hair tension plate that applies appropriate tension to the needle thread 1 from the needle thread supply source.

FIG. 3 is a block diagram showing the control system circuit in this embodiment. In the figure, 42 is a CPU, 43 is a potentiometer that detects the height of the presser foot (not shown) and outputs the detection result as weight information, and 44 is a feed amount for one stitch (feed pitch) input by the operator. ) is a feed pinch signal output device that outputs a signal representing . Further, the sewing machine applied to this embodiment is a zigzag stitch sewing machine, and numeral 45 does not indicate a needle oscillation signal output device for outputting a signal representing the amount of needle oscillation input by the operator in this zigzag stitch sewing machine. 46 is a main shaft phase detector that detects the phase of the main shaft 23, and approximately 85
Detection signals are output at 1106° and 1106 principal axis phases. Then, the CPU 42 receives the output from the above 43, 44, 45, the photo ink clubter 40, and the main shaft phase detector 46.
The CPU 2 controls the solenoid 39 based on these inputs.

Based on the above configuration, the operation of this embodiment will now be explained with reference to the flowchart of FIG. 4 and the timing chart of FIG. 5.

First, when the drive roller of the sewing machine is started, initial settings are performed, and then, based on the detection signal from the main shaft phase detector 46, feed pinch information is transmitted at a predetermined main shaft phase (approximately 110°).
The needle swing information and weight information are loaded (step 1.2)
Based on this information, the amount of thread required to form one stitch is calculated and stored in the memory 47 (step 3).
). Next, based on the detection signal from the main shaft phase detector 46, the solenoid 39 is turned off (step 5) when the main shaft phase is 85°, in other words, when the thread take-up begins to relax the needle thread (step 4). As a result, the roller plate 34
Since the clamping is released, the first pulley 27 rotates. Note that until the solenoid 39 is turned off, that is,
While the solenoid 39 is turned on and clamps the roller plate 34, the 21st pulley 33 is prevented from rotating together with the rotating shaft 31.
A load greater than the coupling friction force between 7 and the drive shaft 25 is
This is applied via the timing heald 38, and slippage occurs at the joint surface between the stopper 30 and the 11th relay 27.
The 1-pulley 27 does not rotate, and only the drive shaft 25 rotates.
It is spinning against the opponent.

Then, as described above, when the solenoid 39 is turned off, the load applied to the first pulley 27 is significantly reduced, and the eleventh pulley 27 rotates integrally with the drive shaft 25 due to the frictional force. The rotation is transmitted to the second pulley 33 via the timing belt 38, and the rotating shaft 31, drive roller 32, and detection plate 35 rotate together with this pulley 33.

As the drive roller 32 rotates, the upper thread τ held between the drive roller 32 and the driven roller 36 is fed in the direction of the thread take-up. At this time, as the drive roller 32 rotates, the photo ink printer 40 outputs pulses as shown in FIG. It is determined whether the number of pulses corresponding to the required amount of yarn has been reached (Step 6), and if the number of pulses has been reached, the solenoid 39 is turned ON (
Step 7). As a result, the solenoid 39 clamps the roller plate 35, the rotation of the roller 33 is stopped, and the feeding of the upper thread (3) is stopped. In addition, when stopping, as mentioned above,
The drive shaft 25 idles relative to the first pulley 27.

Thus, in this embodiment, the solenoid 39
Since the rotation of the drive roller 32 is directly restrained or unrestricted, there is no need to apply unnecessary tensile force to the needle thread 1 when it is stopped, and the needle thread τ does not elongate. In addition, since the solenoid 39 is designed to sandwich the roller plate 34, a constant restraint state can always be obtained regardless of the type of upper thread I, and accurate stopping operation can be performed stably. .

In the above embodiment, due to the internal space of the sewing machine, a rotary shaft 31 is provided separately from the drive shaft 25, and a drive roller 32 is attached to the rotary shaft 31. The drive roller 32 is directly connected to the drive shaft 25, but is not limited to this embodiment.
The first pulley 27 may be attached to the drive shaft 25 by frictional force in the same manner as the first pulley 27. In this case, the 1.2 pulleys 27, 3
3. Since the timing belt 38, rotating shaft 31, etc. can be omitted, the construction can be made at low cost.

〔Effect of the invention〕

As explained above, according to the present invention, no matter what kind of needle thread there is, the needle thread does not stretch or shift when the feeding is stopped, and accurate feeding operation is stabilized. The effect is that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the present invention, FIG. 2 is a side view of the same as shown in FIG. 1, FIG. 3 is a block diagram showing the control system circuit of this embodiment, and FIG. FIG. 5 is a flowchart showing the operation procedure in this embodiment. FIG. 5 is a timing chart showing the operation timing in this embodiment.
This figure is a perspective view showing an automatic needle thread supply device in a conventional sewing machine, and FIG. 7 is a partially enlarged side view of the device shown in FIG. 6. 32... Drive roller 36... Driven roller

Claims (1)

[Claims] A pair of opposing rollers grips the needle thread from the needle thread supply source, and at least one of the rollers is used as a drive roller to rotate it in a predetermined direction, thereby moving the needle thread toward the thread take-up. In an automatic upper thread feeding device for a sewing machine configured to feed a predetermined amount of needle thread, roller restraining means for restraining or unrestricting the rotation of the drive roller is provided, and the drive roller is caused to have friction against a drive shaft that rotates along with the driving of the sewing machine. connected by force so that the drive roller slides relative to the drive shaft in a restrained state by the restraint means, and rotates integrally with the drive shaft in a state not restrained by the restraint means; A detection means for detecting the amount of rotation of the drive roller is provided, and when the amount of rotation detected by the detection means when the drive roller is not restrained reaches the amount of rotation corresponding to the amount of yarn required for one stitch, the restraining means is brought into a restrained state. An automatic upper thread feeding device for a sewing machine, characterized in that: