JP3143185B2 - Needle thread supply device of sewing machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upper thread supply device for a sewing machine, in which an upper thread is fed by a pair of pulleys driven by a motor, and more particularly, the upper thread feeding is related to the number of rotations of the sewing machine. The present invention relates to a needle thread supply device for a sewing machine which is designed to perform the above operation.

[0002]

2. Description of the Related Art Conventionally, the number of revolutions of a motor for rotating a pulley for feeding an upper thread is determined only by a feed pitch of the upper thread detected by a potentiometer mounted on a feed adjusting table of a sewing machine head. Was.

[0003] That is, the timing of feeding out the upper thread for each rotation of the sewing machine is limited in section (angle) by counting the tachogenesis pulse (hereinafter abbreviated as TG pulse) of the generator stator mounted on the upper shaft of the sewing machine. Therefore, the payout time of the upper thread allowed per one rotation of the sewing machine depends on the rotation speed of the sewing machine.

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

As described above, the supply amount of the upper thread is directly proportional to the rotation speed of the motor for rotating the pulley for feeding the upper thread, so that the amount of the upper thread that can be fed is determined by the rotation speed of the sewing machine and the motor speed. And the number of rotations.

[0006]

By the way, in the conventional upper thread supply device of the sewing machine, since the rotation speed of the sewing machine is fixed to the maximum value of the specification, the sewing is actually performed at a lower rotation speed. Even when it was running, the rotation speed of the motor was getting high.

However, from the viewpoint of the stability of the needle thread feeding, it is desirable that the rotational speed of the motor for rotating the pulley for feeding the needle thread be as low as possible. This is because it is desired to minimize the variation in the payout at the beginning and end of the payout for each needle.

That is, the upper thread supply device needs to feed out an accurate amount of the upper thread. However, if a variation in the feeding occurs, a defect such as uneven sewing occurs.

SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides a needle thread supply device for a sewing machine capable of stably sewing out a needle thread at a low motor rotation speed corresponding to the actual rotation speed of the sewing machine and performing stable sewing. The purpose is to provide.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, a needle thread supply device for a sewing machine according to the present invention has a pair of pulleys which are driven to rotate by a motor and can be joined to each other. A control means for inputting a feed pitch of the upper thread and a maximum rotation number of the sewing machine and calculating a rotation number of the motor , wherein the control means calculates a rotation number of the motor ; Holds yarn at downstream side of pulley
And a controllable yarn gripping member.
This thread gripping member releases the thread at the delivery timing
Is controlled in such a manner .

[0011]

According to the present invention, by entering the feed pitch and number of machine rotations of the upper yarn to the control unit, the best of the sewing machine the rotation speed of the motor capable of supplying the thread on the amount required by the control means
Since so as to drive the motor by the rotation speed set based on the rotational speed, written to the actual variation in the number of machine rotations
The needle thread is fed out stably at the motor speed set to a constant speed, and the thread is positioned downstream of the pulley and grips the thread.
A thread gripping member that can be moved by the control means.
So that this thread gripper releases the thread during
As a result, it is possible to perform stable sewing having an appropriate seam .

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 shows a main part of a needle thread supply device, in which a first solenoid 1 for holding and holding an upper thread S derived from a thread winding of an upper thread (not shown) between an armature 2 and the like. Has been established. When the first solenoid 1 is energized, it holds the upper thread S between the armature 2 and the upper thread S.

A feeding roller 3 for feeding out the upper thread S is disposed downstream of the first solenoid 1 in the feeding direction of the upper thread S. This feeding roller 3
Are a driving roller 4A and a driven roller 4B that can be joined to each other.
As shown in FIG. 2, a coupling 5 is provided on the lower drive roller 4A.
The motor 6 is connected via a drive roller 4A, and the driving roller 4A is driven to rotate by the driving of the motor 6. Further, the driving roller 4A and the driving roller 4A
Gears 7A and 7B that can mesh with each other are fitted to the back of the driven roller 4B located above the driving roller 4B.
The rotation of the drive roller 4A is transmitted to the driven roller 4B in a state where the roller A and the driven roller 4B are joined.

On the substrate 8 above the driven roller 4B,
An arm 10 is pivotally connected at one end by a support pin 9 and is rotatable in a vertical plane. The arm 10 is always positioned substantially horizontally, and a bracket 11 that extends downward and holds the driven roller 4B so as to be rotatable is vertically provided at an intermediate portion in the longitudinal direction of the arm 10. ing. 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 driving roller 4A is attached to the tip of the arm 10. Further, below the distal end of the arm 10, a latch solenoid 13 is provided in which a plunger 14 projecting from the upper end is in contact with the arm 10. This plunger 14
When the power is supplied, the plunger 14 projects upward, rotates the arm 10 clockwise, and separates the driven roller 4B from the driving roller 4A.

An upper thread guide member 15 for guiding the upper thread S is disposed downstream of the rollers 4A and 4B in the feeding direction of the upper thread S. Is provided with a second solenoid 16 as a thread gripping member for holding the upper thread S between the armature 17 and holding it. When the second solenoid 16 is energized, the upper thread S is sandwiched and held between the second solenoid 16 and the armature 17.

On the other hand, the sewing machine is provided with a feed dog (not shown) which feeds the cloth by projecting upward from the needle plate by performing an elliptical motion. The feed pitch at which the cloth is fed by the feed dog is detected. A known feed pitch detection mechanism is shown in FIG.

As shown in FIG. 3, the feed pitch detecting mechanism includes a feed adjusting dial 1 for setting a feed pitch.
8 has a feed adjusting base 19 that changes its angle in conjunction with the rotation of the rotary body 8, and a rotary fork member 20 that rotates integrally with the feed adjusting base 19 is fixed to the feed adjusting base 19. . The fork arm 21 is formed downward on the rotating fork member 20.

In the vicinity of the lower portion of the rotating fork member 20, a pushing arm 22 is rotatably supported at its lower end by a support pin 23. At the upper end of the push arm 22, a pin 24 is fitted on the rotary fork member 20 so as to fit relatively tightly inside the fork arm 21. The pushing arm 22 is driven to rotate in conjunction with the rotation of the member 20.

In the vicinity of the pushing arm 22, a potentiometer 25 is provided. This potentiometer 25
Has a plunger 26 that can move forward and backward, and changes the linear movement of the plunger 26 to a voltage value. The tip of the plunger 26 is in pressure contact with the pushing arm 22, and the plunger 2
6 can move linearly. Thus, the feed pitch set by operating the feed adjusting dial 18 can be converted into a voltage value by the potentiometer 25.

CPU (not shown) for performing various controls of the sewing machine
Changes the rotation speed of the motor 6 that drives the rollers 4A and 4B for feeding out the upper thread S based on the voltage value input from the potentiometer 25, and controls the feed pitch of the upper thread S. ing. For this reason, the memory connected to the CPU is provided with a correspondence table between 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 rotation speed of the sewing machine, it is necessary to detect the rotation speed of the sewing machine. By the way, 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 the 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 a calculation for setting the rotation speed of the motor 6 for driving the rollers 4A and 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 limit switch will be described.

Assuming that the feed pitch P _D of the upper thread S is 2 mm and the number of rotations N of the sewing machine is 2000 spm, the upper thread S of one rotation (360 °) of the upper shaft of the sewing machine for one stitch is sewn.
Angle θ = 21, which is the angle at which the feeding is performed
Since the angle is 7.5 °, the time t that can be fed out of the upper thread S per stitch is as follows: t = 60 sec / 2000 spm × 217.5 ° / 360 ° = 18.2 msec (1)

Therefore, within the time t of the above equation (1), 2
mm The number of revolutions N of the motor 6 capable of feeding out the upper thread S
Can be expressed by the following equation. 60 sec / Nrpm × 20 pulses / 400 pulses <18.12 × 10 ⁻³ sec (2) In the above equation (2), the pulse is a motor encoder pulse for driving the motor 6, and is equal to 0.1 pulse per pulse.
The feed amount of the upper thread S is 1 mm. One rotation of the motor 6 results in 400 pulses.

From the above equation (2), N> 165.6 rpm, and in this case, the rotation speed of the motor 6 is 200 rpm
m.

Next, the operation of this embodiment having the above-described configuration will be described. In this description, the numerical values of the above equations (1) and (2) are referred to for convenience.

When a pedal (not shown) is turned on, first, the feed pitch of the upper thread S set by the feed adjusting dial 18 and the maximum rotation speed of the sewing machine are read into the CPU. 6 is calculated and set.

Then, when sewing is started, the motor 6 is driven at the set constant speed (200 rpm).
As a result, the driving roller 4A and the driven roller 4B that are joined to each other are rotated, and the upper thread S sandwiched between the rollers 4A and 4B is to be paid out. However, in the initial state, the first solenoid 1 and the second solenoid 16 are energized, respectively, and hold the upper thread S between the respective armatures 2 and 17, so that the upper thread S is unreeled. Not.

Then, when the rotation angle of the upper shaft reaches a timing suitable for feeding out the upper thread S, first, the power supply to the first solenoid 1 is released. Then, both rollers 4A,
The upper thread S held between the rollers 4B is fed out by the rotation of the rollers 4A and 4B. However, since the second solenoid 16 is still energized and holds the upper thread S between the armature 17 and the upper thread S, the upper thread S is not actually fed out, and the second solenoid 16 In the foreground, it will be loosened and stored.

When the number of motor encoder pulses for driving the motor 6 which has started counting after the energization of the first solenoid 1 is released reaches 20 which is the set number,
The energization of the first solenoid 1 is resumed, and the supply of the upper thread S is stopped to hold the upper thread S between the armature 2 and the upper thread S.

Thereafter, when the rotation angle of the upper shaft reaches the timing at which the upper thread S is actually fed in the direction of the balance, the power supply to the second solenoid 16 is released, and the upper thread S is moved between the upper solenoid S and the armature 17. To release from pinching,
The needle thread S that has been loosened and stored is fed out in the direction of the balance,
This will contribute to sewing. Then, when the rotation angle of the upper shaft reaches a timing at which the feeding of the upper thread S in the direction of the balance is stopped, the power supply to the second solenoid 16 is resumed, and the upper thread S is held between the upper arm S and the armature 17. In order to hold the upper thread S, the feeding of the upper thread S is stopped.

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

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

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made as necessary.

[0036]

As described above, according to the present invention, it is possible to stably carry out the needle thread feeding at a constant rotational speed of the motor irrespective of the actual fluctuation of the rotational speed of the sewing machine. Also,
Has a thread gripping member located downstream of the
At the time of the line feeding timing by the control means,
Since the thread gripping member releases the thread,
An excellent effect that stable sewing having a seam can be performed can be achieved.

[Brief description of the 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 a roller in FIG. 1;

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st solenoid 3 Feeding roller 4A Drive roller 4B Follower roller 6 Motor 13 Latch solenoid 16 2nd solenoid 18 Feed adjustment dial 19 Feed adjustment table 20 Rotary fork member 22 Pushing arm 25 Potentiometer

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) D05B 45/00

Claims (1)

(57) [Claims] 1. An upper thread supply device for a sewing machine that has a pair of pulleys that are driven by a motor and that can be joined to each other, and that holds an upper thread between both rotating pulleys and feeds the upper thread. Control means for calculating the number of rotations of the motor by inputting the yarn feed pitch and the maximum number of rotations of the sewing machine ;
A yarn gripping member which is located downstream and can grip the yarn ,
This yarn is controlled by the control means at the yarn feeding timing.
An upper thread supply device for a sewing machine, wherein the gripper controls the release of the thread.