JP2022157390A - Thread feeding device for sewing machine - Google Patents

Abstract

To control rotation speed of a thread feeding roller according to the sewing speed of a sewing machine which makes seams by a needle thread and a looper thread.SOLUTION: In a mechanism of a sewing machine which has a needle and a looper and which makes seams by a needle thread and a looper thread, a thread feeding device for a sewing machine forcibly delivers the needle thread and the looper thread by a rotating thread feeding roller, with the needle thread amount and the looper thread amount for making the seams. The thread feeding device for a sewing machine includes: a thread feeding roller 8 comprising at least a pair of needle thread roller 16 and looper thread roller 17; a thread feeding roller drive servo motor 9 for rotationally driving the thread feeding roller 8 being independent of a main shaft of the sewing machine; a pressing member 10 for separately holding the needle thread and the looper thread with the thread feeding roller 8; and a control device 19 for changing rotation speed Nr, Lr of the thread feeding roller drive servo motor 9 according to the sewing speed Mr of the sewing machine.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thread feeding device for controlling the rotational speed of a thread feeding roller in accordance with the sewing speed of a sewing machine that forms stitches with a needle thread and a looper thread.

In a conventional thread feeding device, the amount of needle thread and looper thread that make up a stitch is forcibly fed out by a rotating thread feeding roller. , a driven roller, and a thread gripper, and the thread gripped by the driving roller and the driven roller is forcibly sent out by releasing the thread gripping of the thread gripper only in a predetermined section in one stitch configuration section (Patent Document 1) , Patent Document 2).

In a double chainstitch sewing machine with a single needle, the operator changes the path of the needle thread by the sewing machine to produce "relatively hard stitches", "soft stitches", and "neither too hard nor too soft stitches". A sewing machine needle thread control mechanism (Patent Document 3) is disclosed in which the hardness of each stitch for each material can be appropriately adjusted like a stitch.
In interlock stitch sewing machines, the difference (BA) between "the thread supply path length A at the top dead point of the needle bar" and "the thread supply path length B at the needle bar bottom dead point" causes hard stitches (minimum (Patent Document 4) discloses a needle thread take-up device for a sewing machine that adjusts a soft stitch (maximum difference) and a soft stitch (maximum difference). Further, there is disclosed a thread take-up device for a sewing machine (Patent Document 5) that adjusts hard stitches (long thread path) and soft stitches (short thread path) according to the length of the needle thread path.

JP-A-4-35682 JP-A-5-192477 JP-A-46-6631 JP-A-2002-273085 JP-A-2003-979

However, in the conventional thread supply device that forcibly feeds out the needle thread and looper thread amount constituting one stitch by a rotating thread supply roller, the sewing speed of the sewing machine is 6000 spm, that is, If the one-stitch construction time is 10 ms, the gripping section control of the thread gripper will be repeated in less than 0.01 seconds, and the control device will be expensive.
In addition, when the hardness of the stitches is changed according to the properties of the material to be sewn or the type of clothing, the needle thread path difference and the needle thread path length are set by the operator by changing the positions of the sewing machine parts.

SUMMARY OF THE INVENTION An object of the present invention is to control the rotation speed of a thread supply roller according to the sewing speed of a sewing machine.

The invention according to claim 1,
A rotating thread supply roller forces the amount of needle thread and looper thread forming a stitch to the mechanism of a sewing machine that has a needle and a looper and forms a stitch with the respective needle thread and looper thread. In a thread feeding device for a sewing machine that feeds a needle thread and a looper thread, the thread feeding device
a yarn supply roller comprising at least a pair of needle yarn rollers and a looper yarn roller;
a driving body that rotates and drives the yarn supply roller independently from the main shaft of the sewing machine;
a pressing member that holds the needle thread and the looper thread separately with the thread supply roller;
and a control device for changing the rotation speed of the driving member according to the sewing speed of the sewing machine.

The invention according to claim 2 is the thread feeding device for a sewing machine according to claim 1,
The sewing machine has at least two needles to form interlock stitches, the control device has an input device for setting the thread amount composition of the stitches, and the driver operates according to the thread amount composition signal from the input device. is characterized by changing the rotation speed of the

The invention according to claim 3 is the thread feeding device for a sewing machine according to claim 2,
The driving body is characterized by being a servomotor.

The invention according to claim 4 is the thread feeding device for a sewing machine according to claim 2,
The driving bodies are provided independently on the needle thread roller and the looper thread roller, respectively.

The invention according to claim 5 is the thread feeding device for a sewing machine according to claim 2,
The diameter of the looper thread roller is larger than the diameter of the needle thread roller.

The invention according to claim 6 is the thread feeding device for a sewing machine according to claim 1,
The pressing member is a driven roller that rotates as the yarn supply roller rotates.

Since the present invention controls the rotational speed of the thread supply roller according to the sewing speed of the sewing machine, it does not control the thread supply timing in the section constituting one stitch. As a result, the sewing machine can be used for high-speed sewing without requiring an expensive control device.
Further, in the interlock stitch sewing machine, since the rotation speed of the thread supply roller is controlled according to the amount of thread forming the stitches, the thread for forming the stitches can be set by the input device without changing the setting positions of the sewing machine members by the operator. It is possible to change the amount.

Conceptual diagram of the present invention. A diagram of a modeled stitch form 407 of the present invention. The control block diagram of this invention. FIG. 2 is a graph showing the relationship between the number of rotations of the thread supply roller and the number of rotations of the main shaft of the sewing machine. FIG. 4 is a diagram of a thread supply device in a conventional interlock stitch sewing machine.

An embodiment of the present invention will be described below with reference to the drawings. In order to facilitate understanding of the present invention, a conventional yarn feeding device will be described with reference to FIG. FIG. 5 shows a thread supply device 2 provided in a three-needle interlock stitch sewing machine 1 disclosed in Patent Document 1. As shown in FIG. This conventional yarn supply device 2 has a needle yarn roller 3 and a looper yarn roller 4 which rotate at a constant speed, and a yarn gripper 5 is provided for each yarn on the upstream side of the yarn supply flow. On the downstream side, there is a thread handling mechanism of the interlock stitch sewing machine, and the needle 6 and the looper 7 that constitute the interlock stitch are disclosed.

FIG. 1 is a conceptual diagram of a thread feeding device and a sewing machine mechanism according to the present invention. The yarn supply roller 8 is connected to a yarn supply roller drive servomotor 9 (shown in FIG. 3) so that rotation of the shaft of the yarn supply roller drive servomotor 9 is directly linked to rotation of the yarn supply roller 8 . The pressing member 10 pinches the yarn 11 with the yarn supply roller 8 . The thread 11 is forcibly sent to the sewing machine mechanism by the rotation of the thread supply roller. The sent-out thread 11 passes through a thread handling mechanism composed of a fixed thread guide 12 and a vertical movable thread guide 13 and reaches the needle 6 .

FIG. 2 shows a modeled 3-needle stitch type 407 (JIS L 0120) of the present invention. The upper side of FIG. 2 shows the needle thread 14 on the side of the stitch, and the lower side shows the looper thread 15 on the back side of the stitch. A indicates needle movement (amount of cloth feed), B indicates thickness of cloth (one sheet), and C indicates needle width (needle interval).

From the three-needle stitch pattern 407 modeled in FIG. 2, the approximate formula for the needle thread amount NL and the looper thread amount LT constituting the first stitch is obtained as follows.
NL=A+(2B×2) (1)
LT=5A+2C+2×√(A^2+C^2) (2)
Using the same method, the approximate calculation formula for the looper thread amount LT constituting one stitch is obtained from the two-needle stitch type 406 and the single-needle stitch type 401 defined in JIS L 0120, resulting in the following formula. rice field.
Twin needle stitch type 406
LT=4A+C+√(A^2+C^2) (3)
1-needle stitch type 401
LT=3A (4)
Assuming that D is the number of needles in formulas (2), (3), and (4), the following formulas hold.
LT=(2+D)A+(D-1)C+(D-1)×√(A^2+C^2) (5)

In order to verify the validity of the approximate calculation formulas (1) and (2), three types of stitch types 407, "hard stitches", "soft stitches" and "stretch stitches", were used for needle thread based on sewing experiments. Quantity and looper yarn quantity were used.
The experimental conditions under which each yarn amount was measured are as follows.
Stitches: 50 stitches in a sewing section of 100 mm (needle movement or stitches)
The length of the first stitch (cloth feeding amount) is 2 mm. Therefore, A = 2.
Cloth: milling cloth with a thickness of 0.4 mm, therefore B = 0.4
Needle width of 3 needles: 5.6 mm Therefore, C = 2.8
Yarn: The results of spun yarn sewing experiments are as follows.
"Hard stitches": needle thread amount (approximately 230-240 mm), looper thread amount (approximately 1100 mm)
"Soft stitches": Needle thread amount (approximately 270-280 mm), looper thread amount (approximately 1200 mm)
"Stretch stitch": Needle thread amount (approximately 300 to 400 mm), looper thread amount (approximately 1100 mm)

When the approximate calculation formulas (1) and (2) were compared with the results of sewing experiments based on the distinction between stitches, the following correction value λ was added to the approximate calculation formula.
"hard seams"
Needle thread amount λ=1.1
Looper yarn amount λ = -0.48
"Soft seams"
Needle thread amount λ=1.9
Looper thread amount λ=1.52
"stretch seams"
Needle thread amount λ=3.4
Looper yarn amount λ = -0.48
Therefore, the correction value λ is added to the equations (1) and (5) for the needle thread amount NL and the looper thread amount LT in one stitch as follows.
NL=A+(2B×2)+λ (6)
LT=(2+D)A+(D-1)C+(D-1)×√(A^2+C^2)+λ (7)

The rotation speed Nr (rpm) of the needle thread roller 16 (not shown) and the rotation speed Lr (rpm) of the looper thread roller 17 (not shown) in the thread supply roller 8 are controlled by the sewing machine main shaft drive servo motor 18 (see FIG. 3). ) and the rotational speed Mr (rpm) are as follows.
Needle thread roller radius: Rn
Nr=(NL×Mr)/2πRn=(NL/2πRn)×Mr (8)
Radius of looper thread roller: Rl
Lr=(LT×Mr)/2πRl=(LT/2πRl)×Mr (9)

FIG. 4 shows the rotation speed Nr (rpm) of the needle thread roller 16, the rotation speed Lr (rpm) of the looper thread roller 17, and the sewing machine main shaft rotation speed Mr (rpm) (sewing machine main shaft drive servomotor 18) under the following conditions. It is a graph showing the relationship.
<Conditions> Length unit: mm
Length of first stitch: A = 2
Cloth thickness: B = 0.4
Needle width (needle spacing): C = 2, 8
Number of needles: D = 3 (pcs)
Needle thread roller radius: Rn=10
Radius of looper thread roller: Rl = 20
It is calculated by Equations (6), (7), (8) and (9).
From FIG. 4, the number of revolutions (rotational speed) of the thread supply roller increases or decreases according to the number of revolutions (sewing speed) of the main shaft of the sewing machine. Further, even if the number of rotations (sewing speed) of the sewing machine main shaft is the same, the number of rotations (rotational speed) of the thread supply roller increases or decreases according to the distinction between stitches (thread amount configuration).
It is desirable that the yarn supply roller driving servo motor 9 is provided independently for the needle yarn roller 16 and the looper yarn roller 17 respectively.
Since the amount of looper thread is about 3 to 5 times larger than the amount of needle thread, it is desirable that the looper thread roller has a larger radius than the needle thread roller.
The pressing member 10 is preferably a driven roller that presses the yarn supply roller 8 with a spring, an air cylinder, or an electromagnetic solenoid.

FIG. 3 is a block diagram of the electrical control of the present invention. The control device 19 has a CPU 20 , a ROM 21 , a RAM 22 and an EEPROM 23 . A sewing machine spindle drive servo motor 18 is driven by a drive circuit 25 via a controller 19 in response to a signal from a sewing machine spindle drive pedal 24 . Numerical values for controlling the number of revolutions of the yarn supply roller drive servomotor 9 are input to the control device by an input operation section (input device) 26 . The numerical values are obtained from the numerical formulas (6), (7), (8), and (9), the number of revolutions Nr (rpm) of the needle thread roller 16 (not shown) and the number of revolutions of the looper thread roller 17 (not shown). Used to calculate Lr (rpm). Equations (6), (7), (8) and (9) are all stored in EEPROM 23 of control device 19 . A signal from the sewing machine main shaft drive pedal 24 is used as a signal of the rotation speed Mr of the sewing machine main shaft drive servomotor 18 in equations (8) and (9). The sewing machine main shaft driving servomotor 18 is driven according to the signal from the sewing machine main shaft driving pedal 24 , and the thread supply roller driving servomotor 9 is driven through the drive circuit 27 by the signal from the controller 19 .

1 Conventional interlock stitch sewing machine 2 Conventional thread supply device 3 Needle thread roller 4 Looper thread roller 5 Thread gripper 6 Needle 7 Looper 8 Thread supply roller 9 Thread supply roller drive servo motor 10 Pressing member 11 Thread 12 Fixed thread path 13 Top and bottom Dynamic thread guide 14 Needle thread 15 Looper thread 16 Needle thread roller (not shown)
17 looper thread roller (not shown)
18 Sewing machine spindle drive servo motor 19 Control device 20 CPU
21 ROMs
22 RAMs
23 EEPROM
24 sewing machine spindle drive pedal 25 drive circuit 26 input operation unit (input device)
27 Drive circuit A Needle operation (cloth feeding amount)
B Fabric thickness C Needle width (needle spacing)
D Number of needles NL Amount of needle thread (one stitch)
LT Looper thread amount (first stitch)
λ Correction value Nr Number of rotations of needle thread roller Lr Number of rotations of looper thread roller Mr Number of rotations of sewing machine main shaft drive servomotor 18

Claims (6)

A rotating thread supply roller forces the amount of needle thread and looper thread forming a stitch to the mechanism of a sewing machine that has a needle and a looper and forms a stitch with the respective needle thread and looper thread. In a sewing machine thread feeding device for feeding needle thread and looper thread,
The yarn supply device is
a yarn supply roller comprising at least a pair of needle yarn rollers and a looper yarn roller;
a driving body that rotates and drives the yarn supply roller independently from the main shaft of the sewing machine;
a pressing member that holds the needle thread and the looper thread separately with the thread supply roller;
A thread feeding device for a sewing machine, comprising: a control device for changing the rotation speed of a driving member according to the sewing speed of the sewing machine. The sewing machine has at least two needles to form interlock stitches, the control device has an input device for setting the thread amount composition of the stitches, and the driver operates according to the thread amount composition signal from the input device. 2. The thread feeder for a sewing machine according to claim 1, wherein the rotational speed of the thread feeder is changed. 3. A thread feeding device for a sewing machine according to claim 2, wherein said driving member is a servomotor. 3. A thread feeding device for a sewing machine according to claim 2, wherein the driving bodies are provided independently for the needle thread roller and the looper thread roller. 3. A yarn feeding device according to claim 2, wherein the diameter of the looper yarn roller is larger than the diameter of the yarn roller. 2. A thread feeding device for a sewing machine according to claim 1, wherein the pressing member is a driven roller that rotates as the thread feeding roller rotates.

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