JP3974460B2 - Yarn tension control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thread tension control device for a sewing machine, and more particularly, to control a device by detecting a rotational position of a thread take-up spring in a specific section of a sewing machine spindle phase.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been proposed a yarn tension control device in which a tension applying member is provided on a yarn path that extends from a spool disposed on a sewing machine to a needle hole through a balance. In this apparatus, the upper thread tension is varied by electrically controlling the tension applying member. The control of the yarn tension control device is performed by detecting the sewing speed based on the number of rotations of the sewing machine because it is difficult to measure the yarn tension.
[0003]
[Problems to be solved by the invention]
However, the thread tension changes with each stitch formation depending on various conditions such as the cloth thickness, cloth density, stepped portion, thread thickness, thread material, and humidity as well as the sewing speed. For this reason, even when the stitch is formed by controlling the thread tension control device based on the sewing speed, a uniform stitch cannot be obtained at the sewing portion. Further, if various conditions are detected for each stitch formation and the thread tension control device is controlled, uniform stitches can be obtained. However, for this purpose, a plurality of sensors are required, and the device is expensive. Problems arise.
[0004]
The present invention has been made to solve the above problems, and provides an apparatus for forming uniform stitches on a sewing product by detecting the thread tension with an inexpensive apparatus and controlling the thread tension. For the purpose.
[0005]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1
A support member disposed on a yarn path from the spool to the balance;
A thread take-up spring having a thread hook at its tip, and rotatably supported by the support member;
A yarn tension adjusting member disposed 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 capable of setting the thread tension;
In the yarn tension control device capable of changing the yarn tension by operating the driving means to the set value of the setting means,
A detecting means for detecting a rotation position of the thread take-up spring when the hook exceeds the phase and an initial displacement phase in the hook fastening section;
Based on the output value of the detecting means, the thread tension at the time of sewing is obtained, the thread tension at the time of sewing is compared with the thread tension set by the setting means, and the driving means is controlled to increase or decrease the tension. It was set as the structure provided with a control means.
[0006]
According to the first aspect of the present invention, the thread tension adjusting member is controlled by the rotation position of the thread take-up spring at the phase beyond the hook and the initial displacement phase in the hook tightening section of the thread take-up spring. A uniform seam can be formed. Further, since the apparatus is controlled by the specific detection signal, the control is easy.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
1st Embodiment of this invention is described based on FIGS.
[0010]
The upper thread 1 reaches the sewing needle 7 through the thread winding 2 disposed on the upper part of the sewing machine arm through the thread tension adjusting member 3, the thread take-up spring mechanism 4, the thread guide 5 and the balance 6. This route is referred to as a yarn route 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.
In the center of the pair of thread tension plates 8 and 9, fitting holes 8a and 9a are formed. The movable iron core 10 includes a head portion 10a and a shaft portion 10b that is thinner in the radial direction than the head portion 10a. The shaft portion 10b of the movable iron core is passed through the fitting holes 8a and 9a of the thread tension plate. The head 10a of the movable iron core supports the thread tension plates 8 and 9, and the shaft portion 10b loosely fits the thread tension plates 8 and 9. Further, after passing through the fitting holes 8a and 9a of the thread tension plate, the shaft portion 10b of the movable iron core is mounted in the sliding hole 11a of the plunger magnet. When the magnet 11 (driving means) is excited, the movable iron core 10 is attracted. By this suction operation, the pair of thread tension plates 8 and 9 move to the thread tension adjusting member cover portion 3a side. Further, this attractive force increases and decreases according to the current value applied to the magnet. For this reason, the upper thread 1 held between the pair of thread tension plates 8 and 9 is given a pressure corresponding to the attractive 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 disposed close to the yarn path 16. An arc-shaped through groove (penetrating portion) 12 b is formed on the side surface of the support member 12.
[0014]
The thread take-up spring 14 is formed of a rod-like member and is rotatably supported on the center shaft 12a of the support member. The thread take-up spring 14 has a semi-arc-shaped thread hook 14a at the tip. The thread take-up spring 14 protrudes from the through groove 12b of the support 12, and the thread hook 14a engages with the upper thread. The thread take-up spring 14 is urged clockwise by a winding spring (not shown), but comes into contact with the upper end of the arcuate 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 dotted line position (horizontal position) in FIG.
[0015]
The detection plate (detection means) 13 is rotatably supported by the central shaft 12a of the support member 12. Further, the detection plate 13 is fixed to the base side of the thread take-up spring 14 and rotates integrally with the thread take-up spring 14. The detection plate 13 is semicircular and has an arc-shaped detection portion 13a. A proximity sensor 15 (detection means) is fixed in the vicinity of the detection unit 13 a of the detection plate 13. For this reason, when the rotational 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 located at the dotted line position (horizontal position) in FIG.
[0016]
Next, the configuration and input / output of the control device for controlling the sewing machine will be described with reference to FIG.
This control device (control means) 22 is supplied with various signals (sewing speed 17, sewing phase signal 18, thread take-up spring position signal 19) and setting conditions (setting thread tension 20, needle as sewing condition 21, thread type) from the outside. , Yarn count) is input via an input interface (not shown). Then, the internal CPU performs a comparison operation with data set in the ROM or RAM, and controls the current to the magnet 11 of the yarn tension adjusting member 3 according to the set tension via an output interface (not shown). The control information is displayed to the worker by the display device 23. Further, based on FIG. 5 for controlling the driving of the sewing machine motor 24, the relationship between the thread pulling displacement of the balance and the shuttle and the stroke (displacement of the swinging angle) of the thread take-up spring 14 with respect to the machine spindle rotational phase of this apparatus will be described. . The horizontal axis in FIG. 5 is the main spindle rotational phase, and is θ0 when the needle bar is at the top dead center position.
[0017]
The indicated curve circle 1 is the upper thread supply amount curve of the balance 6, and the circle 2 is the upper thread necessary amount curve of the hook. Circles 3 to 5 are displacement curves of the thread take-up spring 14, circle 3 is when the tension is weak, circle 4 is when the tension is medium, and circle 5 is when the tension is strong.
As is apparent from the curve circle 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 is apparent from the curve circle 2 , the required amount of the upper thread of the hook gradually increases from the phase θ3 at which the needle pierces the cloth, and becomes maximum immediately before the hook releases the upper thread at the phase θ4.
This sewing machine main shaft rotational phase θ4 is a hook over-phase. A section sandwiching the hook excess phase θ4 is a hook fastening section T, and the hook fastening section T is, for example, 280 to 320 degrees.
[0018]
In the hook tightening section T, the waveform of the displacement amount curve circles 3 to 5 of the thread take-up spring changes according to the strength of the thread tension. In particular, when attention is paid to the displacement amount at the hook excess phase θ4, it is 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, and h3 at the hook crossing phase (θ4) are in a proportional relationship. Therefore, it is possible to convert the yarn tension during sewing thread take-up spring displacement of this.
[0019]
Further, the thread tension value is different even when the thread tension is large and the displacement amount of the thread take-up spring is the full stroke h3 (when the thread take-up spring 14 shown in the dotted line in FIG. 3 is in the horizontal position) at the hook crossing phase (θ4). For this reason, when the displacement amount 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. As is apparent from the thread take-up spring displacement amount curve in FIG. 5, when the yarn tension increases, the initial phase of the displacement is indicated by θ12, θ11, and θ10, and the rising timing of the displacement phase is advanced. Using this phenomenon, the yarn tension is converted.
[0020]
Next, an example of processing of this control device will be described based on FIG.
First, turn on the device power.
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 sewing machine rotation speed, detection and calculation processing of the sewing machine spindle phase, and detection and calculation processing of the thread take-up spring position are performed. Then, it is determined whether the sewing machine spindle phase has reached the hook fastening section T (S2).
[0022]
Next, when the hook tightening section T is reached, it is determined whether or not the thread take-up spring displacement amount at the time of the hook over phase θ4 is the full stroke h3 (S3).
If it is not the full stroke h3, the current thread tension is calculated based on the displacement of the thread take-up spring at the hook crossing phase, 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). In order to determine the initial displacement phase, the initial rising timing of the first proximity sensor 15 after determining that the full stroke h3 is determined in S3 is obtained from the sewing machine phase signal 18 or has already occurred in the determined hook tightening section T. Is obtained from the sewing phase signal 18.
[0024]
In addition, the thread tension calculation in S4 and S5 is performed by comparing with data set in the ROM or RAM.
[0025]
Next, the set yarn tension input in S1 is compared with the current yarn tension obtained in S4 and S5 (S6). If the set thread tension and the current thread tension are the same, the process is terminated. If not, 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 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, thread tension can be controlled with an inexpensive device, and uniform stitches can be formed on the sewn product.
[0027]
The present invention can be variously modified without being limited to the above embodiment.
For example, a fabric step changeover switch is connected to the input side of the control device. Then, at the time of sewing having the cloth step portion, the cloth step portion changeover switch is turned on. When sewing the fabric step, the thread tension increases rapidly. By controlling the thread tension adjustment member so that the tension is increased at the balance thread tightening timing, uniform stitches can be formed on the fabric step. it can.
[0028]
In the above-described embodiment, the setting value is input by the operator from the outside. However, instead of this, the setting value may be automatically given from the sewing condition 21. In the above embodiment, the set value and the detected current thread tension are compared and calculated, but instead, the value from the data table is automatically called from the comparison with the set value, and the thread tension adjusting member 3 It is also conceivable to control the current to the magnet 11.
[0029]
In the above embodiment, the magnet is used as the driving means for the yarn tension adjusting member, but it is also conceivable to use a piezoelectric element or the like instead. Further, in the above embodiment, the yarn tension adjusting member 3 and the thread take-up spring mechanism 4 are individually provided along the yarn path. However, the thread take-up spring mechanism is laminated on the yarn tension adjusting member 3 and integrally formed. It is also easy to do. Furthermore, in the above-described embodiment, the proximity sensor 15 and the detection plate 13 are used as 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 invention of Claim 1,
Since the thread tension adjusting member is controlled by the rotation position of the thread take-up spring when it exceeds the hook and the initial displacement phase in the hook tightening section of the thread take-up spring, uniform stitches can be more reliably formed on the sewing product. it can.
Further, since the apparatus 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 cross-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 a thread take-up spring when the thread tension is strong, medium, and weak with respect to the sewing machine spindle rotation phase.
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 device (control means)

Claims (1)

A support member disposed on a yarn path from the spool to the balance;
A thread take-up spring having a thread hook at its tip, and rotatably supported by the support member;
A yarn tension adjusting member disposed 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 capable of setting the thread tension;
In the yarn tension control device capable of changing the yarn tension by operating the driving means to the set value of the setting means,
A detecting means for detecting a rotation position of the thread take-up spring when the hook exceeds the phase and an initial displacement phase in the hook fastening section;
Based on the output value of the detecting means, the thread tension at the time of sewing is obtained, the thread tension at the time of sewing is compared with the thread tension set by the setting means, and the driving means is controlled to increase or decrease the tension. A yarn tension control device comprising a control means.

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