JPH05212182A - Needle thread supply device of sewing machine - Google Patents

Abstract

PURPOSE:To pay off a needle thread stably with a low motor revolving speed corresponding to the revolving speed of a sewing machine by furnishing a control means to calculate the motor revolving speed through entry of the needle thread feed pitch and the machine revolving speed. CONSTITUTION:A rotary fork 20 is secured to a feed regulating table 19 which changes the angle in association with the rotation of a feed regulator dial 18 provided for setting the feed pitch, and a push arm 22 rotates in following-up in linkage with the rotation of the rotary fork 20. A potentiometer 25 installed in the neighborhood of the push arm 22 has a plunger 26 capable of advancing and retreating so as to convert the linear motion of the plunger 26 into a voltage value. A CPU sets the revolving speed of a motor which drives rollers 4A, 4B for paying off the needle thread S on the basis of the voltage value of the potentiometer 25 and the machine revolving speed of a max. speed control switch. The max. revolving speed of the sewing machine and the feed pitch of the needle thread S set by the feed regulator dial 18 are read into the CPU, which calculates the revolving speed of the motor, and thus setting is made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a needle thread supply device for a sewing machine, in which the needle thread is fed by a pair of pulleys which are rotationally driven by a motor, and more particularly, the needle thread feeding is related to the sewing machine rotation speed. The present invention relates to a needle thread feeder for a sewing machine.

[0002]

2. Description of the Related Art Conventionally, the rotational speed of a motor for driving a pulley for feeding the upper thread is determined only by the feeding pitch of the upper thread detected by a potentiometer mounted on a feed adjusting base of the sewing machine head. It was

That is, the timing of feeding the upper thread for each revolution of the sewing machine is limited by the count of tachogenerator pulses (hereinafter abbreviated as TG pulse) of the generator stator mounted on the upper shaft of the sewing machine. Therefore, the upper thread take-out time allowed for each rotation of the sewing machine depends on the number of rotations of the sewing machine.

Further, the supply amount of the upper thread required for each one rotation of the sewing machine is determined by the feed pitch of the sewing machine and the thickness of the sewing material. Of these, the feed pitch of the sewing machine is determined by the potentiometer, and the thickness of the sewing material is set by a correction volume (feed adjustment dial) provided separately.

As described above, the supply amount of the upper thread is directly proportional to the rotational speed of the motor that rotationally drives the upper thread feeding pulley. And the number of rotations of

[0006]

By the way, in the conventional needle thread feeder of the sewing machine, since the sewing machine rotation speed is fixed at the maximum value of the specification, sewing is actually performed at a lower rotation speed. Even at that time, the rotation speed of the motor was high.

However, from the viewpoint of the stability of the upper thread feeding, it is desirable that the number of rotations of the motor for rotationally driving the upper thread feeding pulley is as low as possible. This is because it is desired to minimize variations in the yarn feeding at the beginning and the end of the yarn feeding for each needle.

That is, it is necessary for the upper thread supply device to pay out an accurate amount of the upper thread, but if unevenness in the payout occurs, it causes defects such as uneven sewing.

In view of the above-mentioned points, the present invention provides a needle thread supply device for a sewing machine, which is capable of stably delivering the upper thread at a low motor rotation speed corresponding to the actual sewing machine rotation speed and performing stable sewing. The purpose is to provide.

[0010]

In order to achieve the above-mentioned object, a needle thread feeder of a sewing machine of the present invention has a pair of pulleys which are driven to rotate by a motor and can be joined to each other. In a needle thread supply device for a sewing machine that feeds out an upper thread by sandwiching an upper thread between the pulleys, a control means for inputting an upper thread feed pitch and a sewing machine rotational speed to calculate the rotational speed of the motor is provided. It has a feature.

[0011]

According to the present invention, the feed pitch of the upper thread and the rotational speed of the sewing machine are input to the control means, and the rotational speed of the motor capable of supplying the required amount of the upper thread is set by the control means. Since the motor is driven by the rotation speed, the upper thread can be fed out stably at a low motor rotation speed corresponding to the actual sewing machine rotation speed, and stable sewing can be performed.

[0012]

The present invention will be described below with reference to the embodiments shown in the drawings.

FIG. 1 shows an essential part of an upper thread supply device, in which a first solenoid 1 for holding and holding an upper thread S, which is drawn out from an unillustrated upper thread winding, with an armature 2 is arranged. It is set up. When the first solenoid 1 is energized, the upper thread S is sandwiched and held between the armature 2 and the upper thread S.

A feeding roller 3 for feeding the upper thread S is arranged downstream of the first solenoid 1 in the feeding direction of the upper thread S. This feeding roller 3
Is a driving roller 4A and a driven roller 4B that can be joined to each other.
Of these, the drive roller 4A located below the drive roller 4A has a coupling 5 as shown in FIG.
The motor 6 is connected via the motor 6, and the drive roller 4A is driven to rotate by driving the motor 6. Further, the drive roller 4A and the drive roller 4A
Gears 7A and 7B capable of meshing with each other are fitted to the back of the driven roller 4B located above the drive roller 4B.
The rotation of the drive roller 4A is transmitted to the driven roller 4B in a state where A and the driven roller 4B are joined.

On the substrate 8 above the driven roller 4B,
An arm 10 is supported whose one end is pivotally attached by a support pin 9 and is rotatable in a vertical plane. The arm 10 is always positioned substantially in the horizontal direction, and a bracket 11 that extends downward and rotatably holds the driven roller 4B is integrally provided at an intermediate portion in the longitudinal direction of the arm 10. ing. Further, one end of a coil spring 12 for attaching the arm 10 in a counterclockwise direction in FIG. 1 to press the driven roller 4B against the drive roller 4A is attached to the tip of the arm 10. Further, below the tip of the arm 10, there is provided a latch solenoid 13 in which a plunger 14 protruding from the upper end is in contact with the arm 10. This plunger 14
Is energized, the plunger 14 projects upward to rotate the arm 10 in the clockwise direction to separate the driven roller 4B from the drive roller 4A.

An upper thread guide member 15 for guiding the upper thread S is arranged downstream of the rollers 4A and 4B in the feeding direction of the upper thread S. Is provided with a second solenoid 16 that holds the upper thread S by sandwiching the upper thread S with the armature 17. When the second solenoid 16 is energized, it holds the upper thread S by sandwiching it with the armature 17.

On the other hand, the sewing machine is provided with a feed dog (not shown) which projects upward from the needle plate by performing an elliptical motion and feeds the cloth. The feed tooth detects the feed pitch for feeding the cloth. A known feed pitch detection mechanism is shown in FIG.

The feed pitch detection mechanism, as shown in FIG. 3, is a feed adjustment dial 1 for setting the feed pitch.
It has a feed adjusting base 19 whose angle is changed in association with the rotation of the rotary body 8, and a rotary fork member 20 which rotates integrally with the feed adjusting base 19 is fixed to the feed adjusting base 19. .. A fork arm 21 is formed downward on the rotating fork member 20.

A push arm 22 is rotatably supported at its lower end by a support pin 23 near the lower part of the rotary fork member 20. On the upper end portion of the pushing arm 22, a pin 24, which is fitted relatively tightly inside the fork arm 21, is projectingly provided on the rotating fork member 20, and therefore, the rotating fork. The push arm 22 is driven to rotate in association with the rotation of the member 20.

A potentiometer 25 is arranged near the pushing arm 22. This potentiometer 25
Has a plunger 26 that can move forward and backward, and changes the linear movement of the plunger 26 into a voltage value. The tip of the plunger 26 is in pressure contact with the pushing arm 22, and the plunger 2 moves as the pushing arm 22 rotates.
6 can move linearly. Thereby, the feed pitch set by operating the feed adjusting dial 18 can be converted into a voltage value by the potentiometer 25.

A CPU (not shown) for performing various controls of the sewing machine
Controls the feed pitch of the upper thread S by changing the number of rotations of the motor 6 for driving the rollers 4A and 4B for feeding the upper thread S based on the voltage value input from the potentiometer 25. ing. Therefore, the memory connected to the CPU is provided with a correspondence table of the voltage value and the feed pitch of the upper thread S.

Further, since the present invention is for controlling the feed pitch of the upper thread S so as to correspond to the actual rotational speed of the sewing machine, it is necessary to detect the rotational speed of the sewing machine. By the way, on the operation panel (not shown) of the sewing machine,
There is a maximum speed limit switch for controlling the rotation speed of the sewing machine, and this maximum speed limit switch is used to limit the maximum rotation speed of the sewing machine. The maximum rotation speed of the sewing machine is the rotation speed of the sewing machine when the pedal is fully depressed. Therefore, the value of the maximum speed limit switch is input to the control means.

An example of calculation for setting the rotation speed of the motor 6 for driving the rollers 4A, 4B for feeding the upper thread S based on the voltage value of the potentiometer 25 and the rotation speed of the sewing machine of the maximum speed limiting switch will be described.

When the feed pitch P _D of the upper thread S is 2 mm and the number of revolutions N of the sewing machine is N = 2000 spm, the upper thread S is included in one rotation (360 °) of the upper shaft of the sewing machine for sewing one stitch.
Angle of feed = θ = 21
Since it is 7.5 °, the time t that the upper thread S can be fed out per needle is t = 60 sec / 2000 spm × 217.5 ° / 360 ° = 18.2 msec (1).

Therefore, within the time t of the equation (1), 2
mm Number of rotations N of the motor 6 that can feed the upper thread S
Can be expressed by the following equation. 60 sec / N rpm × 20 pulses / 400 pulses <18.12 × 10 ⁻³ sec (2) In the above formula (2), a pulse is a motor encoder pulse for driving the motor 6, and a pulse of 0.
The amount of the upper thread S fed out is 1 mm. Further, one rotation of the motor 6 results in 400 pulses.

Since N> 165.6 rpm is obtained from the equation (2), the rotation speed of the motor 6 is 200 rp in this case.
set to m.

Next, the operation of this embodiment having the above-mentioned structure will be described. In this description, the numerical values of the expressions (1) and (2) described above are cited for convenience.

When a pedal (not shown) is turned on, first, the feed pitch of the needle thread S set by the feed adjusting dial 18 and the maximum number of rotations of the sewing machine are read into the CPU. Based on these values, the motor in the CPU is read. The rotation speed of 6 is calculated and set.

Then, when sewing is started, the motor 6 is driven at a set rotation speed (200 rpm), whereby the driving roller 4A and the driven roller 4 which are joined to each other.
B is rotated and the upper thread S held between the rollers 4A and 4B is about to be fed out. However, in the initial state, the first solenoid 1 and the second solenoid 16 are
Since each is energized and holds the upper thread S by sandwiching it between the armatures 2 and 17, the upper thread S is not fed out.

When the rotation angle of the upper shaft reaches a timing suitable for feeding the upper thread S, first, the power supply to the first solenoid 1 is released. Then both rollers 4A,
The upper thread S sandwiched between 4B is fed by the rotation of both rollers 4A and 4B. However, since the second solenoid 16 is still energized and holds the upper thread S by sandwiching the upper thread S with the armature 17, the upper thread S is not actually delivered and the second solenoid 16 is It will be stored loosely in the foreground.

After the energization of the first solenoid 1 is released, when the number of motor encoder pulses for driving the motor 6 which has started counting reaches the preset number of 20 pulses,
The energization of the first solenoid 1 is restarted, and the upper thread S is held by being sandwiched between the upper thread S and the armature 2. Therefore, the feeding of the upper thread S is stopped.

After that, when the rotation angle of the upper shaft reaches the timing at which the upper thread S is actually fed out in the balance direction, the second solenoid 16 is de-energized, and the upper thread S is moved between the armature 17 and the upper thread S. To release from pinching,
The loosened and stored upper thread S is fed out in the balance direction,
It will contribute to sewing. Then, when the rotation angle of the upper shaft reaches the timing to stop the feeding of the upper thread S in the balance direction, the energization of the second solenoid 16 is restarted, and the upper thread S is clamped between the armature 17 and the upper thread S. The upper thread S is stopped to be fed out and held.

In this way, the feeding of the upper thread S corresponding to the sewing of one stitch is completed, and thereafter, when the rotation angle of the upper shaft at the second stitch becomes a timing suitable for the feeding of the upper thread S, The energization of the first solenoid 1 is released, and the sewing is continued by repeating the above operation. The sewing is ended by turning off the pedal.

According to the above-described embodiment of the present invention, the proper rotation speed of the motor 6 is set by the feed pitch of the needle thread S set by the feed adjustment dial 18 and the maximum rotation speed of the sewing machine. An accurate amount of upper thread can be fed out, and sewing with a good finish can be performed.

The present invention is not limited to the above-described embodiments, but various modifications can be made if necessary.

[0036]

As described above, according to the present invention, the superior effect that the upper thread can be stably fed out at a low motor rotation speed corresponding to the actual sewing machine rotation speed and stable sewing can be performed. Can be played.

[Brief description of drawings]

FIG. 1 is a front view of a main part showing an embodiment of the present invention.

FIG. 2 is an enlarged side view of the vicinity of the roller of FIG.

FIG. 3 is a side view of a feed pitch detection mechanism.

[Explanation of symbols]

 1 First Solenoid 3 Feeding Roller 4A Drive Roller 4B Driven Roller 6 Motor 13 Latch Solenoid 16 Second Solenoid 18 Feed Adjustment Dial 19 Feed Adjustment Base 20 Rotating Fork Member 22 Pushing Arm 25 Potentiometer

Claims (1)

[Claims] 1. A needle thread supply device for a sewing machine, which has a pair of pulleys which are driven to rotate by a motor and can be joined to each other, and which holds the needle thread between the rotating pulleys and feeds the needle thread. A needle thread supply device for a sewing machine, which is provided with control means for calculating a rotation speed of the motor by inputting a yarn feed pitch and a rotation speed of the sewing machine.