JP2004008713A - Thread tension controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost thread tension controller which can detect and control thread tension. <P>SOLUTION: This thread tension controller has: a support member (12) which is placed on the thread passage from the bobbin to the needle thread take-up; a thread take-up spring (14) which has a thread catch part on the tip end part and is rotatably supported by the support member (12); a thread tension regulating member (3) which is placed on the thread passage and can give tension to the thread; a drive means (11) which drives the thread tension regulating member to regulate the thread tension; detecting means (13, 15) which detect the rotation position of the thread take-up spring in a thread tension regulator to regulate thread tension at a value preset by the presetting means by actuating the drive means; and a control means (22) which compares thread tension with the preset value on the basis of the detection output of a hook fastening zone of the main shaft phase from the detecting means to regulate thread tension. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thread tension control device for a sewing machine, and more particularly to a device for controlling a device by detecting a rotation position of a thread take-up spring in a specific section of a phase of a main shaft of the sewing machine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a thread tension control device has been proposed in which a tension applying member is provided on a thread path extending from a thread winding disposed above a sewing machine, through a balance, and to a needle hole. This device varies the needle thread tension by electrically controlling a tension applying member. Since the thread tension is difficult to measure, the control of the thread tension control device is performed by detecting the sewing speed based on the number of rotations of the sewing machine.
[0003]
[Problems to be solved by the invention]
However, the thread tension changes every stitch formation depending on various conditions such as the sewing speed, but also the cloth thickness, the cloth density, the step portion, the thread thickness, the thread material, the humidity, and the like. For this reason, even if the stitch is formed by controlling the thread tension control device based on the sewing speed, a uniform stitch cannot be obtained in the sewn portion. Further, if various conditions are detected every stitch formation and the thread tension control device is controlled, a uniform stitch can be obtained. However, for that purpose, a plurality of sensors are required, and the device becomes expensive. Problems arise.
[0004]
SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and provides an apparatus for forming a uniform stitch on a sewing product by detecting a thread tension with an inexpensive apparatus and controlling the thread tension. The purpose is to:
[0005]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 is:
A support member (12) arranged on a yarn path from the spool to the balance;
A thread take-up spring (14) having a thread catching portion at its tip end and rotatably supported by the support member;
A yarn tension adjusting member (3) arranged on the yarn path and capable of applying tension to the yarn;
Driving means (11) for driving the yarn tension adjusting member to vary the yarn tension;
Setting means for setting the thread tension;
In the yarn tension control device capable of changing the yarn tension by operating the driving unit to the set value of the setting unit,
Detecting means (13, 15) for detecting the rotational position of the thread take-up spring;
A control means (22) for controlling the driving means so as to increase or decrease the thread tension in comparison with the set value based on the detection output of the sewing machine main shaft phase detected by the sewing machine spindle phase.
[0006]
According to the first aspect of the present invention, the rotational position of the thread take-up spring in the hook tightening section of the sewing machine main shaft phase is detected, and the thread tension adjusting member is controlled based on the detected output. For this reason, the thread tension can be controlled with an inexpensive device, and uniform stitches can be formed on the sewing product.
[0007]
According to a second aspect of the present invention, in the yarn tension control device according to the first aspect,
The thread take-up spring projects from a through portion provided on a side surface of the support member,
The detecting means detects a rotation position of the thread take-up spring during the phase exceeding the hook and an initial displacement phase in the hook fastening section,
The control unit is configured to control the drive unit to increase or decrease the tension based on the output value of the detection unit, as compared with the set value.
[0008]
According to the second aspect of the present invention, the thread tension adjusting member is controlled by the rotation position of the thread take-up spring during the phase exceeding the hook and the initial displacement phase of the thread take-up spring in the hook tightening section. A uniform seam can be formed. Further, since the device is controlled by the specific detection signal, the control is easy.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIGS.
[0010]
The upper thread 1 reaches a sewing needle 7 from a thread winding 2 disposed above the sewing machine arm via a thread tension adjusting member 3, a thread take-up spring mechanism 4, a thread guide 5, and a balance 6. This path is referred to as a yarn path 16.
[0011]
As shown in FIG. 2, the thread tension adjusting member 3 includes a pair of thread tension plates 8 and 9, a movable iron core 10, and a plunger magnet 11.
Fitting holes 8a, 9a are formed at the centers of the pair of thread tension discs 8, 9. The movable iron core 10 includes a head portion 10a and a shaft portion 10b which is thinner in a radial direction than the head portion 10a. The shaft portion 10b of the movable iron core passes through the fitting holes 8a and 9a of the thread tension disc. The head 10a of the movable core supports the thread tension plates 8, 9, and the shaft portion 10b loosely fits the thread tension plates 8, 9. After passing through the fitting holes 8a and 9a of the thread tension disc, the shaft portion 10b of the movable iron core is attached to the sliding hole 11a of the plunger magnet. When the magnet 11 (drive means) is excited, the movable iron core 10 is attracted. By this suction operation, the pair of thread tension discs 8 and 9 move toward the thread tension adjusting member cover 3a. Further, the attraction force increases and decreases according to the current value applied to the magnet. Therefore, the upper thread 1 sandwiched between the pair of thread tension discs 8 and 9 is given a pressure corresponding to the attraction force of the plunger magnet, that is, a predetermined thread tension.
[0012]
The thread take-up spring mechanism 4 includes a support member 12, a detection plate 13, a thread take-up spring 14, and a proximity sensor 15.
[0013]
The support member 12 is fixed to the sewing machine frame and is arranged close to the thread path 16. On the side surface of the support member 12, an arc-shaped through groove (through portion) 12b is formed.
[0014]
The thread take-up spring 14 is formed of a rod-shaped member, and is rotatably supported by the center shaft 12a of the support member. The tip end of the thread take-up spring 14 has a semi-arc-shaped thread hook 14a. The thread take-up spring 14 protrudes from the through groove 12b of the support 12, and its thread hooking portion 14a engages with the upper thread. Then, the thread take-up spring 14 is urged clockwise by a winding spring (not shown), but contacts the upper end of the arc-shaped through groove 12b and stops at the position indicated by the solid line in FIG. When the thread tension increases, the thread take-up spring rotates counterclockwise, but comes into contact with the lower end of the arc-shaped through groove 12b and stops at the position indicated by the dotted line in FIG. 3 (horizontal position).
[0015]
The detection plate (detection means) 13 is rotatably supported by the center shaft 12 a of the support member 12. The detection plate 13 is fixed to the base of the thread take-up spring 14 and rotates integrally with the thread take-up spring 14. The detection plate 13 has a semi-disc shape, and has an arc-shaped detection portion 13a. A proximity sensor 15 (detection means) is fixed near the detection unit 13a of the detection plate 13. Therefore, when the rotation position of the thread take-up spring 14 changes, the output signal of the proximity sensor 15 changes. The proximity sensor 15 is set so that the thread take-up spring position signal 19 generates a maximum output signal when the thread take-up spring 14 is positioned at the dotted line position (horizontal position) in FIG.
[0016]
Next, the configuration and input / output of a control device for controlling the sewing machine will be described with reference to FIG.
Various signals (sewing machine rotation speed 17, sewing machine phase signal 18, thread take-up spring position signal 19) and setting conditions (setting thread tension 20, sewing conditions 21 as needles and thread types) are externally provided to the control device (control means) 22. , Yarn count) are input via an input interface (not shown). The internal CPU compares the data with the data set in the ROM or RAM, and controls the current to the magnet 11 of the thread tension adjusting member 3 according to the set tension via an output interface (not shown). The control information is displayed on the display device 23 for the worker. Further, the relationship between the thread pulling displacement of the balance and the shuttle and the stroke (displacement of the swing angle) of the thread take-up spring 14 with respect to the rotation phase of the sewing machine main shaft of the apparatus will be described with reference to FIG. . The horizontal axis in FIG. 5 is the rotation phase of the main shaft of the sewing machine, and is set to θ0 when the needle bar is at the top dead center position.
[0017]
The illustrated curve (1) is the upper thread supply amount curve of the balance 6, and (2) is the upper thread required amount curve of the shuttle. (3) to (5) are displacement curves of the thread take-up spring 14, (3) is a case where the tension is weak, (4) is a case where the tension is medium, and (5) is a case where the tension is strong. .
As is clear from the curve (1), the upper thread supply amount of the balance 6 is minimum at the sewing machine spindle rotation phase θ1 and maximum at the phase θ2. Further, as apparent from the curve (2), the required amount of the upper thread of the shuttle increases gradually from the phase θ3 at which the needle pierces the cloth, and reaches the maximum just before the shuttle releases the upper thread at the phase θ4. This sewing machine spindle rotation phase θ4 is a phase exceeding the shuttle. The section T sandwiching the phase exceeding the shuttle hook θ4 is a shuttle fastening section, and the shuttle fastening section T is, for example, 280 degrees to 320 degrees.
[0018]
In the hook tightening section T, the waveform of the displacement amount curve (3) to (5) of the thread take-up spring changes according to the strength of the thread tension. In particular, focusing on the displacement amount at the phase exceeding the shuttle hook θ4, h1 when the tension is weak, h2 when the tension is medium, and h3 when the tension is strong. At this time, the thread tension and the displacement amounts h1, h2, h3 during the phase exceeding the hook (θ4) are in a proportional relationship. For this reason, the thread tension at the time of sewing can be converted from the thread take-up spring displacement amount.
[0019]
Also, in the phase exceeding the hook (θ4), the thread tension value is different even when the thread tension is large and the displacement of the thread take-up spring is full stroke h3 (when the thread take-up spring 14 shown by the dotted line in FIG. 3 is in the horizontal position). Therefore, when the displacement of the thread take-up spring is the full stroke h3, the thread tension is converted from the initial displacement phase θ10 of the thread take-up spring 14 in the hook tightening section T. This is because, as is clear from the thread take-up spring displacement amount curve in FIG. 5, as the thread tension increases, the initial displacement phase has an earlier rising timing of the displacement phase as shown by θ12, θ11, θ10, This phenomenon is used to convert the yarn tension.
[0020]
Next, an example of the processing of the control device will be described with reference to FIG.
First, the device power is turned on.
Next, the operator inputs the set thread tension (set value) 20 and the sewing condition 21 from the variable dial (S1).
[0021]
Next, when sewing is started, detection and calculation processing of the rotation speed of the sewing machine, detection and calculation processing of the main shaft phase of the sewing machine, detection and calculation processing of the thread take-up spring position are performed. Then, it is determined whether or not the sewing machine spindle phase has reached the hook tightening section T (S2).
[0022]
Next, when it reaches the hook-tightening section T, it is determined whether or not the thread take-up spring displacement amount at the hook-exceeding phase θ4 is the full stroke h3 (S3).
If the stroke is not the full stroke h3, the current thread tension is calculated based on the thread take-up spring displacement during the phase exceeding the shuttle, and the process proceeds to S6 (S4).
[0023]
If it is the full stroke h3, the current thread tension is calculated based on the initial displacement phase of the thread take-up spring 14 in the hook tightening section T, and the process proceeds to S6 (S5). To determine the initial displacement phase, the first rise timing of the first proximity sensor 15 after the full stroke h3 has been determined in S3 is obtained from the sewing machine phase signal 18 or has already occurred in the determined hooking section T. The rising timing is obtained from the sewing machine phase signal 18.
[0024]
In the thread tension calculation in S4 and S5, the calculation is performed by comparing with the data set in the ROM or the RAM.
[0025]
Next, the set thread tension input in S1 is compared with the current thread tension obtained in S4 and S5 (S6). If the set thread tension is the same as the current thread tension, the process is terminated; otherwise, the increase / decrease value of the thread tension is calculated. Based on this increase / decrease value, the control device supplies a control current to the magnet 11 of the yarn tension adjusting member 3.
[0026]
According to the first embodiment, the rotation position of the thread take-up spring in the hook tightening section of the sewing machine main shaft phase is detected, and the thread tension adjusting member is controlled based on the detected output. For this reason, the thread tension can be controlled with an inexpensive device, and uniform stitches can be formed on the sewing product.
[0027]
The present invention can be variously modified without being limited to the above embodiment.
For example, a cloth stage changeover switch is connected to the input side of the control device. Then, at the time of sewing having a stepped portion, the switch for switching the stepped portion is turned on. At the time of sewing the stepped portion of the cloth, the thread tension rises sharply. it can.
[0028]
Further, in the above-described embodiment, the setting value is input externally by the operator. However, instead of this, the setting value may be automatically given from the sewing condition 21. In the above embodiment, the set value is compared with the detected current thread tension. Instead, the value from the data table is automatically called from the comparison with the set value, and the thread tension adjusting member 3 is used. It is easily conceivable to control the current to the magnet 11.
[0029]
Further, in the above embodiment, the magnet is used as the driving means of the thread tension adjusting member, but a piezoelectric element or the like may be easily used instead. Further, in the above embodiment, the thread tension adjusting member 3 and the thread take-up spring mechanism 4 are separately provided along the thread path. However, the thread take-up spring mechanism is laminated on the thread tension adjusting member 3 to be integrally formed. It is easy to think about it. Further, in the above-described embodiment, the proximity sensor 15 and the detection plate 13 are used as the detection means. However, instead of this, an optical sensor and a slit-shaped detection plate may be easily used.
[0030]
【The invention's effect】
According to the first aspect of the present invention, the rotational position of the thread take-up spring in the hook tightening section of the sewing machine main shaft phase is detected, and the thread tension adjusting member is controlled based on the detected output. For this reason, the thread tension can be controlled with an inexpensive device, and uniform stitches can be formed on the sewing product.
[0031]
According to the second aspect of the present invention, the thread tension adjusting member is controlled by the rotation position of the thread take-up spring during the phase exceeding the hook and the initial displacement phase of the thread take-up spring in the hook tightening section. For this reason, a uniform stitch can be more reliably formed on the sewing product. Further, since the device is controlled by the specific detection signal, the control is easy.
[Brief description of the drawings]
FIG. 1 is a front view of a yarn tension control device according to the present invention.
FIG. 2 is a sectional view of a yarn tension adjusting member.
FIG. 3 is a partially enlarged view of FIG. 1;
FIG. 4 is a block diagram of a yarn tension control device.
FIG. 5 is a displacement curve of the thread take-up spring when the thread tension is high, medium, or low with respect to the rotation phase of the main shaft of the sewing machine.
FIG. 6 is a flowchart of the yarn tension control device.
[Explanation of symbols]
12, support member 14, thread take-up spring 3, thread tension adjusting member 13, detection plate (detection means)
15. Proximity sensor (detection means)
11. Magnet (drive means)
22..Control devices (control means)

Claims (2)

A support member arranged on the yarn path from the spool to the balance,
A yarn take-up spring having a yarn hooking portion at its distal end, and rotatably supported by the support member;
A yarn tension adjusting member arranged on the yarn path and capable of applying tension to the yarn,
Driving means for driving the yarn tension adjusting member to vary the yarn tension;
Setting means for setting the thread tension;
In the yarn tension control device capable of changing the yarn tension by operating the driving unit to the set value of the setting unit,
Detecting means for detecting a rotational position of the thread take-up spring;
A yarn tension control device comprising: control means for controlling the driving means so as to increase or decrease the tension based on the detection output of the sewing machine main shaft phase in the hooking section of the sewing machine in comparison with the set value. . The yarn tension control device according to claim 1,
The thread take-up spring projects from a through portion provided on a side surface of the support member,
The detecting means detects a rotation position of the thread take-up spring during the phase exceeding the hook and an initial displacement phase in the hook fastening section,
The yarn tension control device according to claim 1, wherein the control unit controls the driving unit to increase or decrease the tension based on an output value of the detection unit, as compared with the set value.

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