JP4189090B2 - Sewing thread 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.
[0002]
[Prior art]
FIG. 2 shows a conventionally known thread tension control device for a sewing machine described in JP-A-6-343784. The yarn tension control device includes a tension detecting device 16, a yarn hook 18, a tension adjusting device 20, and a control means 22 arranged between the yarn supply source 8 and the balance 6. The tension detecting device 16 and the tension adjusting device 20 are connected to the control means 22. The tension adjusting device 20 is composed of two tension plates for clamping the upper thread 24 and an electromagnetic actuator for controlling the clamping pressure. The balance 6 acts on the upper thread 24 when it is raised to tighten the thread.
[0003]
The upper thread 24 from the thread supply source 8 reaches the needle hole of the needle 12 through the tension adjusting device 20, the thread hook 18, the tension detecting device 16, and the balance 6.
[0004]
FIG. 3 shows a thread tension control device for a sewing machine described in Japanese Patent Application Laid-Open No. 7-662. The tension adjusting device 20, the thread hooks 26, 28, and 30, disposed between the thread supply source 8 and the balance 6. It comprises a detection device 16 and a control means 22. Similar to the example of FIG. 2, the tension detecting device 16 and the tension adjusting device 20 are connected to the control means 22. The upper thread 24 reaches the needle hole of the needle 12 through the tension adjusting device 20, the thread hooks 26 and 28, the tension detecting device 16, the thread hook 30, and the balance 6. As in the case of FIG. 2, the tension adjusting device 20 includes two tension plates that clamp the upper thread 24 and an electromagnetic actuator that controls the clamping pressure.
[0005]
FIG. 4 shows a thread tension control device for a sewing machine described in Japanese Patent Publication No. 60-19276, which has a tension adjusting device 20 and a tension detecting device 16 arranged between the yarn supply source 8 and the balance 6. As in the case of FIGS. 2 and 3, the tension adjusting device 20 is also composed of two tension plates for clamping the upper thread 24 and an electromagnetic actuator for controlling the clamping pressure. In the case of this sewing machine, a base tension tray 32 and an encoder 34 are further arranged between the yarn supply source 8 and the tension adjusting device 20.
[0006]
[Problems to be solved by the invention]
However, in any of the examples, the tension control device described above is installed on the balance 6 on the yarn supply source 8 side (hereinafter, the yarn supply source 8 side is referred to as “primary side” and the needle 12 side is referred to as “secondary side”). Has been. For this reason, the following problems arise.
[0007]
5 and 6 are diagrams for explaining the problems of the conventional tension control device. FIG. 5 is a diagram showing the main part of the sewing machine head including the tension control device. FIG. 6 is a thread path 6a of the balance 6. It is sectional drawing which shows the detail of these.
[0008]
In FIG. 5, when the tension control device 36 is operating, the balance 6 is raised in the direction A, and the tension control device 36 generates a tension T1 on the upper thread primary side 24a. This T1 generates a tension T2 on the upper thread secondary side 24b via the balance 6, and the sewing product is tightened. At this time, in the conventional tension control device 36, the tension detecting device 16 detects the tension T1 of the upper thread primary side 24a, and drives the actuator of the tension adjusting device 20 in accordance with the detection result to thereby detect the upper thread secondary. The tension T2 on the side 24b is adjusted.
[0009]
In FIG. 6, the upper thread 24 is bent via the balance thread path surface 6 b that forms the balance thread path 6 a, so that when the scale 6 is raised in the A direction, the upper thread 24 is between the upper thread 24 and the balance thread path surface 6 b. , Frictional resistance R is generated. Because of this frictional resistance R, the tension T1 on the upper thread primary side 24a and the tension T2 on the upper thread secondary side 24b do not match.
[0010]
Therefore, in the case of the conventional tension control device, it is necessary to drive the tension adjusting device 20 in consideration of the frictional resistance R. However, the frictional resistance R varies depending on the rising speed of the balance 6 and the friction coefficient of the upper thread 24. For this reason, the thread tightening tension T2 varies depending on various conditions such as the number of rotations of the sewing machine, the thickness of the upper thread, the material, and the like, and it is necessary for the operator to frequently adjust the tension control device.
[0011]
The object of the present invention is to eliminate the need for frequent data changes by the operator, so that an appropriate tension for the stitch knot can be obtained regardless of the ascending speed of the balance 6 and the friction coefficient of the upper thread 24. An object of the present invention is to provide a thread tension control device for a sewing machine.
[0012]
[Means for Solving the Problems]
To achieve the above objective,
The invention according to claim 1
A slot formed along the vertical direction of the machine frame;
A thread tension which is disposed on the upper end side of the elongated hole and through which a thread from a thread supply source is passed;
Exposed to the sewing machine frame outside from the long hole, while being connected to the sewing machine on the axis, and a scale for performing a yarn tightening acts on falling time thread,
A tension adjusting member disposed on the upper end side of the elongated hole, one end side is rotatably supported by a sewing machine frame, and the other end side is engageable with a thread extending from the balance to the needle hole ;
An actuator for displacing the tension adjusting member in the direction of thread tension;
Detecting means for detecting bending or distortion of the tension adjusting member at the time of thread tightening by the balance;
A control means for driving the actuator by comparing an output value of the detection means with a preset setting value;
The yarn from the yarn supply source sequentially takes the yarn path to the needle hole through the thread tension, the balance, and the tension adjusting member, and the detection means detects the yarn tension on the needle side of the balance. The tension adjusting member is moved in the direction in which the thread tension is applied in accordance with the state in which the thread tension is applied by the balance , and a predetermined stitch is formed.
The invention according to claim 2 is the yarn tension control device for sewing machine according to claim 1,
The detection means is provided below the tension adjusting member, and the actuator is provided above the tension adjusting member, so that the tension adjusting member is displaced in the vertical direction.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described based on the embodiments shown in the drawings.
[0016]
FIG. 1 is a perspective view showing an embodiment of a thread tension control device for a sewing machine according to the present invention. The illustrated sewing machine 2 has a balance 6 disposed in the sewing machine frame 4 and an upper shaft (not shown), and the upper shaft can be rotated by a motor (not shown). The sewing machine frame 4 has a thread supply source (not shown) disposed above and a needle bar 10 disposed below. A needle 12 is fixed to the needle bar 10. The needle bar 10 is connected to the upper shaft and is configured to move up and down as the upper shaft rotates.
[0017]
A long hole 14 is formed in the sewing machine frame 4, and the tip of the balance 6 is exposed to the outside from the long hole 14. A thread path 6 a is formed at the tip of the balance 6. Like the needle bar 10, the balance 6 is also connected to the upper shaft, and its tip can move up and down as the upper shaft rotates. The tip of the balance 6 moves up and down along the long hole 14.
[0018]
Further, one end of a tension adjusting lever (tension adjusting member) 120 is mounted on the sewing machine frame 4 so as to be rotatable about a shaft 120a. A thread passage hole 120b for allowing the upper thread 24 to pass therethrough is formed at the tip end (engagement portion) of the tension adjusting lever 120. The tension adjusting lever 120 is arranged so that the thread passage hole 120b is located in the thread path from the balance 6 to the needle hole 12a of the needle 12.
[0019]
A tension detection sensor 116 capable of detecting the tension of the upper thread 24 is provided below the tension adjustment lever 120. The central portion of the tension adjustment lever 120 is fixed to the tip of the actuator 121. In this way, the tension adjusting lever 120 is configured such that the tip end (engagement portion) thereof is displaced in the vertical direction by the actuator 121 mounted on the sewing machine frame 4. As the tension detection sensor 116, for example, a sensor that is attached to the sewing machine frame 4 and detects the bending of the tension adjustment lever 120 can be used.
[0020]
The controller (control means) 122 stores preset thread tension data, and is connected to a tension detection sensor 116 as an input and an actuator 121 as an output. The controller 122 compares the data input from the tension detection sensor 116 with preset thread tension data, and outputs a difference signal to the actuator 121. The actuator 121 can displace the tip of the tension adjustment lever 120 in the vertical direction in accordance with a signal from the controller 122, and can be constituted by, for example, a piezoelectric element or a voice coil motor.
[0021]
An upper thread 24 from a thread supply source (not shown) is fixed to the balance thread path 6 a of the balance 6, the thread path hole 120 b of the tension adjustment lever 120, and the needle bar 10 through a thread tension 132 attached to the sewing machine frame 4. An upper thread stitch 40 is formed on the cloth 38 through the needle 12.
[0022]
When the balance 6 is lowered in the direction B, the upper thread 24a on the primary side of the yarn path 6a of the balance 6 is T1, the upper thread 24b of the secondary side is T2, and the secondary side of the thread path hole 120b of the tension adjusting lever 120. A thread tension of T2 ′ is generated in the upper thread 24b ′. At this time, the reaction force of (T2 + T2 ′) / 2 is applied to the tension adjusting lever 120 through the yarn passage hole 120b at the tip thereof, and the bending is generated. The tension detection sensor 116 detects this bending, and a detection signal is input to the controller 122. A signal of the difference between this detection signal and the thread tension data preset in the controller 122 is output to the actuator 121.
[0023]
In response to a signal from the controller 122, the actuator 121 rotates the tension adjustment lever 120 about the shaft 120a. The direction of this rotation is such that the difference signal becomes smaller. Accordingly, as the tension adjustment lever 120 rotates, the signal output from the controller 122 to the actuator 121 gradually decreases and becomes 0 when the detected signal becomes equal to the set thread tension data. The lever 120 stops at that position. As apparent from the above description, the thread tension data stored in advance in the controller 122 is data corresponding to (T2 + T2 ′) / 2. Further, unlike the conventional sewing machine, the balance 6 in the present embodiment is configured to act on the upper thread 24 and perform thread tightening when it is lowered.
[0024]
Thus, by making the tension adjusting lever 120 pivotable about the shaft 120a, the tip of the tension adjusting lever 120 can be controlled to move in the direction in which the yarn tensions T2 and T2 'act. By this control, it is possible to obtain a tension for an appropriate stitch knot regardless of the type of thread and the lifting speed of the balance without being affected by the resistance R of the thread path 6a of the balance 6 shown in FIG. It becomes possible. As a result, a beautiful stitch can be obtained without requiring frequent data changes by the operator.
[0025]
The sewing thread tension control device according to the present invention has been described based on the embodiment shown in the drawings, but the present invention is not limited to this and can be variously changed. For example, the tension adjusting lever 120 can be moved up and down to control the thread tension of the upper thread 24. However, the upper thread 24b on the secondary side of the balance 6 is adjusted with the thread tensions T2 and T2 '. Since it is only necessary to be able to control the movement in the acting direction, the tip of the tension adjusting lever 120 can be rotated in the horizontal direction, for example, instead of moving up and down.
[0026]
In addition, although an example of a sensor that is attached to the sewing machine frame 4 and detects the bending of the tension adjusting lever 120 is shown as the tension detection device 16, it is only necessary to detect a value corresponding to the tension of the upper thread 24. A sensor that is attached to the adjustment lever 120 to detect distortion of the tension adjustment lever 120 can also be used.
[0027]
【The invention's effect】
According to the present invention, the thread tension on the secondary side (needle side) of the balance can be controlled regardless of the frictional resistance of the balance. Therefore, it is possible to obtain the tension for the proper stitch knot regardless of the lifting speed of the balance and the friction coefficient of the upper thread. As a result, it is possible to obtain a clean image without requiring frequent data changes by the operator. A seam is obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of a thread tension control device for a sewing machine according to the present invention.
FIG. 2 is a front view showing a conventional example of a thread tension control device for a sewing machine.
FIG. 3 is a front view showing another conventional example of a thread tension control device for a sewing machine.
FIG. 4 is a front view showing still another conventional example of a thread tension control device for a sewing machine.
FIG. 5 is a front view showing a main part of a sewing machine head including a tension control device, for explaining a problem of a conventional tension control device.
FIG. 6 is a cross-sectional view illustrating details of a thread path of a balance, illustrating a problem of a conventional tension control device.
[Explanation of symbols]
T1 Yarn tension on the thread supply side from the balance T2 Yarn tension on the needle side from the balance A Direction of movement of the balance when tightening (conventional example)
B Direction of movement of balance when thread is tightened (Invention) R Friction resistance 2 Sewing machine 4 Sewing machine frame 6 Balance 6a Thread path 6b Balance thread path 8 Thread supply source 10 Needle bar 12 Needle 12a Needle hole 14 Elongate hole 16 Tension detection Device 18 Thread hook 20 Tension adjusting device 22 Control means 24 Upper thread 24a Upper thread primary side 24b Upper thread secondary side 26, 28, 30 Thread hook 32 Base tension plate 34 Encoder 36 Tension controller 38 Cloth 40 Upper thread stitch 116 Tension detection sensor 120 Tension adjustment lever (tension adjustment member) 120a Shaft 120b Thread path hole 121 Actuator 122 Controller (control means) 132 Thread tension

Claims (2)

A slot formed along the vertical direction of the machine frame;
A thread tension which is disposed on the upper end side of the elongated hole and through which a thread from a thread supply source is passed;
Exposed to the sewing machine frame outside from the long hole, while being connected to the sewing machine on the axis, and a scale for performing a yarn tightening acts on falling time thread,
A tension adjusting member disposed on the upper end side of the elongated hole, one end side is rotatably supported by a sewing machine frame, and the other end side is engageable with a thread extending from the balance to the needle hole ;
An actuator for displacing the tension adjusting member in the direction of thread tension;
Detecting means for detecting bending or distortion of the tension adjusting member at the time of thread tightening by the balance;
A control means for driving the actuator by comparing an output value of the detection means with a preset setting value;
The yarn from the yarn supply source sequentially takes the yarn path to the needle hole through the thread tension, the balance, and the tension adjusting member, and the detection means detects the yarn tension on the needle side of the balance. And a predetermined stitch is formed by moving the tension adjusting member in a direction in which the thread tension is applied in accordance with a state in which the thread tension is applied by the balance. In the thread tension control device for a sewing machine according to claim 1,
A thread tension control device for a sewing machine, wherein the detecting means is provided below the tension adjusting member, the actuator is provided above the tension adjusting member, and the tension adjusting member is displaced in the vertical direction.

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