JP2007020791A - Stitch balancing thread tension device for sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stitch balancing thread tension device for a sewing machine facilitating the adjustment of a wide-range thread tension. <P>SOLUTION: This stitch balancing thread tension device 5 for the sewing machine is provided with a shaft member 5a extending in a prescribed direction and a spiral thread guide groove 5b formed to wind around the circumferential face of the shaft member 5a, and is so constituted as to adjust the thread tension applied to the sewing thread according to the length or the number of winding of the sewing thread wound around the shaft member 5a along the thread guide groove 5b and coming into slide contact with the thread guide groove 5b. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thread tension device for a sewing machine.

2. Description of the Related Art Conventionally, there is known a thread tension device for a sewing machine that applies tension to a sewing thread so that a sewing thread passed between a pair of thread tension dishes is held by the thread tension dish (for example, Patent Document 1). reference).
For example, the thread tension device includes a spring that presses each other's thread tension plates, and an electromagnetic solenoid that presses each other's thread tension plates. Both thread tension devices have a thread tension plate. By adjusting the force for pinching the sewing thread and applying an appropriate tension to the sewing thread, a good seam can be formed stably.
Japanese Patent Laid-Open No. 2003-181182

However, in the case of the above prior art, for example, in a thread tension device that presses each thread tension plate with a spring, a predetermined range of tension according to the spring's inherent elastic force is applied to the sewing thread. It has been difficult to adjust a wide range of thread tensions corresponding to various sewing objects, from thin to thick.
Further, in the thread tension device that presses the thread tension plates with each other by the electromagnetic solenoid, in order to apply higher tension to the sewing thread, the current value of the solenoid must be increased, and power consumption increases. There was a problem that the solenoid generated heat.

  An object of the present invention is to provide a thread tension device for a sewing machine that can easily adjust the thread tension in a wide range.

  In order to solve the above problems, the invention described in claim 1 is a thread tension device for a sewing machine, and is formed so as to wind a shaft member extending in a predetermined direction and a circumferential surface of the shaft member. And a tension is applied to the sewing thread by sliding contact resistance of the sewing thread guided by the thread guiding groove.

  According to the first aspect of the present invention, the thread tension device of the sewing machine has a spiral thread guide groove formed so as to wind around the peripheral surface of the shaft member, and is guided by the thread guide groove. The tension applied to the sewing thread can be adjusted by sliding contact resistance according to the length of the sewing thread.

  According to a second aspect of the present invention, in the thread tension device of the sewing machine according to the first aspect, the thread guide groove is formed so as to wind the peripheral surface of the shaft member a plurality of times, and the sewing thread is along the thread guide groove. The tension applied to the sewing thread is adjusted according to the number of turns wound around the shaft member.

  According to the second aspect of the present invention, the thread tension device of the sewing machine has a spiral shape formed so as to wind the peripheral surface of the shaft member a plurality of times while exhibiting the same operation as the first aspect of the invention. The tension applied to the sewing thread can be adjusted according to the number of turns of the sewing thread wound around the shaft member along the thread guiding groove.

According to the first aspect of the present invention, the thread tension device of the sewing machine has a spiral thread guide groove formed so as to wind around the peripheral surface of the shaft member, and is guided by the thread guide groove. The tension applied to the sewing thread can be adjusted by sliding contact resistance according to the length of the sewing thread.
Specifically, by winding the sewing thread around the shaft member along the thread guide groove of the shaft member of the thread tension device, the sewing thread comes into sliding contact with the peripheral surface of the shaft member and the thread guide groove. Sliding contact resistance (friction resistance) acts on.
That is, the thread tension device imparts a frictional force to the sewing thread when the sewing thread slides on the thread guide groove of the shaft member. Therefore, the longer the length that the sewing thread slides on the thread guide groove, the higher the frictional force. The lower the frictional force applied to the sewing thread is, the lower the frictional force is applied to the sewing thread.
The thread tension device can apply tension to the sewing thread based on the frictional force when the sewing thread slides into the thread guide groove and the force by which the sewing thread winds and squeezes the shaft member. The longer the sliding contact with the guide groove is, the higher tension can be applied to the sewing thread, and the shorter the sliding contact is, the lower tension can be applied to the sewing thread.
Therefore, the thread tension device can adjust a wide range of thread tension from a small tension to a large tension and apply it to the sewing thread by adjusting the length of the sewing thread wound along the thread guide groove of the shaft member. it can.
Then, by adjusting the tension applied to the sewing thread by adjusting the length of the sewing thread wound around the shaft member of the thread tension device, the state in which the feeding of the sewing thread is suitable for thin objects and the state suitable for thick objects And can be switched easily.

According to the invention of claim 2, the thread tension device of the sewing machine has the spiral thread guide groove formed so as to wind the circumferential surface of the shaft member a plurality of times, and the thread guide groove The tension applied to the sewing thread can be adjusted in accordance with the number of turns along which the sewing thread is wound around the shaft member.
In other words, the thread tension device imparts a frictional force to the sewing thread when the sewing thread slides into the thread guide groove of the shaft member. Therefore, the higher the number of turns that the sewing thread is wound around the shaft member, the higher the frictional force. Is applied to the sewing thread, and the lower the number of turns that the sewing thread is wound around the shaft member, the lower the frictional force is applied to the sewing thread.
The thread tension device can apply tension to the sewing thread based on the frictional force when the sewing thread slides into the thread guide groove or the force by which the sewing thread winds and squeezes the shaft member. A higher tension can be applied to the sewing thread as the number of turns wound around the member increases, and a lower tension can be applied to the sewing thread as the number of turns wound around the shaft member decreases.
Therefore, the thread tension device can adjust a wide range of thread tensions from a small tension to a large tension and apply them to the sewing thread by adjusting the number of windings of the sewing thread wound along the thread guide groove of the shaft member. it can.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a thread tension device for a sewing machine according to the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a sewing machine having a thread tension device for a sewing machine according to the present invention.

As shown in FIG. 1, the sewing machine 1 is provided with a sewing machine arm 2 formed in a hollow shape.
Inside the sewing machine arm 2 is a needle bar driving mechanism (not shown) that moves the needle bar 10 up and down on the lower side of the front end of the surface of the sewing machine arm 2 based on driving of a sewing machine motor (not shown) serving as a driving source, A balance driving mechanism (not shown) that moves the balance 3 up and down on the upper side of the front end of the surface of the arm 2, a thread winding drive mechanism (not shown) that operates a bobbin winding device 16 that will be described later on the upper surface side of the sewing machine arm 2, etc. Has been.

  As shown in FIGS. 1 and 2, the sewing machine arm 2 is formed with a through groove 21 continuous along the vertical direction of the sewing machine arm 2 from the right side surface to the upper surface with respect to the surface portion on the tip side. Yes. Specifically, the through groove 21 is formed so that the balance 3 can be moved up and down along the movement path of the balance 3.

Further, as shown in FIG. 2, a first thread tension device 4 is provided on the surface of the sewing machine arm 2 at the upper part of the right side with respect to the surface part on the tip side of the sewing machine arm 2, and the second threading device 4 is also provided at the lower part of the right side. The thread tension device 5 is provided.
Further, a thread guide member 6 for guiding the upper thread T from the second thread tension device 5 to the balance 3 and a first fixed thread guide 7 are provided on the surface of the sewing machine arm 2.
Further, on the surface of the sewing machine arm 2, a second fixed thread guide 8 for guiding the upper thread T from the balance 3 to the sewing needle 12 and a needle bar thread guide 9 provided on the jaw 2a of the sewing machine arm 2 are provided. Yes.

  An upper thread T as a sewing thread fed from a thread supply source (not shown) by the balance 3 is a first thread tension device 4, a second thread tension device 5, a thread guide member 6, and a first fixed thread. The guide 7, the balance 3, the second fixed thread guide 8, and the needle bar thread guide 9 are guided along the surface of the sewing machine arm 2 to the needle bar thread hook 11 provided on the needle bar 10, and the sewing needle 12. Is inserted into the needle hole 12a.

The balance 3 is a substantially rod-shaped member, and one end is connected to a balance driving mechanism (not shown) provided in the sewing machine arm 2 and the other end is provided so as to protrude outward from the through groove 21. A thread insertion portion 31 through which the upper thread T is inserted is formed at the other end.
The balance 3 moves the thread insertion portion 31 of the balance 3 up and down so as to be interlocked with the up and down movement of the needle bar 10 (the sewing needle 12) as the balance driving mechanism (not shown) is driven based on the driving of the sewing machine motor. Let
The balance 3 lowers the thread insertion part 31 to feed the upper thread T from a thread supply source (not shown) and feed it to the sewing needle 12 side, and raises the thread insertion part 31. The upper thread T that has been loop-formed by the hook mechanism is pulled up below the needle plate to eliminate the loop, and the upper thread T is tensioned to form a seam.

The first thread tension device 4 includes a pair of thread tension dishes, a spring that presses the thread tension dishes, and an adjustment screw that adjusts the pressing force of the spring.
By passing the upper thread T between the pair of thread tension plates of the first thread tension device 4, the upper thread T is held between the thread tension plates, and the first thread tension device 4 supplies the yarn. Tension is applied to the upper thread T fed from the source.
The first thread tension device 4 can apply a relatively weak tension to the upper thread T according to the elastic force inherent to the spring, and functions effectively when finely adjusting the thread tension.

As shown in FIGS. 2 and 3, the second thread tension device 5 includes a shaft member 5 a that extends in a direction away from the surface side of the sewing machine arm 2 and has a substantially cylindrical shape.
A spiral thread guide groove 5b is formed on the side surface of the shaft member 5a so as to wind the periphery. The yarn guide groove 5b is formed so as to wind the peripheral surface of the shaft member 5a a plurality of times. In this embodiment, as shown in FIG. 3, the yarn guide groove 5b is a peripheral surface of the shaft member 5a. Is wound around three and a half times.
By winding the upper thread T around the shaft member 5a so as to follow the thread guide groove 5b of the shaft member 5a of the second thread tension device 5, the upper thread T is wound around the peripheral surface of the shaft member 5a and the thread guide groove 5b. As a result, the upper thread T is subjected to frictional resistance (sliding resistance). Then, the second thread tension device 5 applies tension to the upper thread T that is fed from the thread supply source and slidably contacts the thread guide groove 5b (shaft member 5a).
The second thread tension device 5 applies tension to the upper thread T based on the frictional force when the upper thread T is in sliding contact with the thread guide groove 5b and the force by which the upper thread T winds and squeezes the shaft member 5a. Thus, the tension applied to the upper thread T can be adjusted in accordance with the length of the upper thread T that is in sliding contact with the thread guide groove 5b. That is, the second thread tension device 5 applies higher tension to the upper thread T as the upper thread T is wound around the shaft member 5a along the thread guide groove 5b, and decreases the winding number. A low tension is applied to the upper thread T.

The second thread tension device 5 is provided with a thread take-up spring 51 that finely adjusts the tension of the upper thread T by applying a relatively small elastic force to the upper thread T.
An upper thread T on the balance 3 side to which tension is applied by the second thread tension device 5 is hung on the thread take-up spring 51. When the tension acting on the upper thread T increases, the thread take-up spring 51 It is elastically deformed and bent toward the yarn guide member 6 on the path balance 3 side. For example, when the tension acting on the upper thread T increases when the balance 3 is raised and the upper thread T is pulled up, the thread take-up spring 51 bends toward the thread guide member 6, and when the tension of the upper thread T decreases, the thread take-up spring 51 The restoring force returns to the initial position before the operation.

The thread guide member 6 is formed in a substantially L shape so that the tip thereof is directed downward on the sewing needle 12 side. The upper thread T is inserted into the L-shaped inner side, and the upper thread T is invite.
The thread guide member 6 is disposed so as to guide the upper thread T hung on the thread take-up spring 51 in a direction away from the balance 3. By arranging the thread guide member 6 in such an arrangement, the thread take-up spring 51 is preferably operated.

The first fixed thread guide 7 and the second fixed thread guide 8 are each bent in a substantially U shape, and the upper thread T is inserted inside the U shape to guide the upper thread T.
The first fixed thread guide 7 guides the upper thread T in the thread path from the thread guide member 6 to the thread insertion part 31 of the balance 3, and the second fixed thread guide 8 moves from the thread insertion part 31 of the balance 3 to the needle bar. The upper yarn T in the yarn path toward the yarn guide 9 is guided.

The needle bar thread guide 9 is a substantially U-shaped member provided on the lower end side of the jaw portion 2a of the sewing machine arm 2, and the upper thread T guided from the balance 3 via the second fixed thread guide 8 is used as the needle bar thread. Guide to the rack 11.
The needle bar thread hook 11 is formed in a cylindrical shape and is attached to the lower end of the needle bar 10, and guides the upper thread T guided by the needle bar thread guide 9 into the needle hole 12 a of the sewing needle 12.

As described above, the second thread tension device 5 disposed in the sewing machine 1 adjusts the length and the number of windings of the upper thread T around the shaft member 5a, thereby adjusting the distance between the shaft member 5a and the upper thread T. The frictional resistance can be switched.
Specifically, by increasing the number of windings around which the upper thread T is wound around the shaft member 5a along the thread guide groove 5b and increasing the length of the upper thread T that is in sliding contact with the thread guide groove 5b, the shaft member 5a (thread The tension applied to the upper thread T can be increased and increased by increasing the frictional force between the guide groove 5b) and the upper thread T.
Further, by reducing the number of windings of the upper thread T around the shaft member 5a along the thread guide groove 5b and shortening the length of the upper thread T that is in sliding contact with the thread guide groove 5b, the shaft member 5a (thread guide groove 5b) ) And the upper thread T, the tension applied to the upper thread T can be made weaker and smaller.
Thus, the second thread tension device 5 can easily adjust the thread tension in a wide range from a small thread tension to a large thread tension by adjusting the number of turns of the upper thread T wound around the shaft member 5a. Can do.
Then, by adjusting the thread tension by adjusting the number of turns of the upper thread T wound around the shaft member 5a of the second thread tension device 5, the state in which the feeding of the upper thread T in the sewing machine 1 is suitable for a thin object, It is possible to easily switch to a state suitable for an object.

In addition, in order to give a higher thread tension to the upper thread T, a thread tension device having a conventional thread tension tray uses a stronger spring elastic force or increases the current value of the electromagnetic solenoid. It is necessary to press each other's thread tension plates more strongly. However, when the upper thread T is strongly clamped by the pair of thread tension plates, the upper thread T is handled strongly, which causes twisting back and deformation of the thread, and trouble such as thread breakage is likely to occur. There was a thing.
In contrast, the second thread tension device 5 may increase the number of turns of the upper thread T that is wound around the shaft member 5a in order to give a higher thread tension to the upper thread T. Tension can be applied to the upper thread T by the frictional force when the upper thread T slides on the member 5a (thread guide groove 5b), so that troubles such as twisting back and deformation are unlikely to occur. Can be granted. In addition, troubles related to heat generation of the electromagnetic solenoid can be prevented.

In addition, as shown in FIGS. 1 and 4, the sewing machine 1 includes a thread guide 13, a third thread tension device 14, a fourth thread tension device 15, and a thread winding device 16 on the upper surface of the sewing machine arm 2. I have.
The thread winding device 16 is a device for winding the sewing thread T, which is a lower thread, around the bobbin B. The thread guide 13, the third thread tension device 14, and the fourth thread tension device 15 wind the sewing thread T around the thread. A tension is applied to the sewing thread T while guiding it to the device 16.

The thread guide 13 guides the sewing thread T fed from a thread supply source (not shown) to the third thread tension device 14.
The third thread tension device 14 includes a pair of thread tension plates, a spring that presses each other, and an adjustment screw that adjusts the pressing force of the spring. By passing the sewing thread T between the pair of thread tension plates of the third thread tension device 14, the sewing thread T is held between the thread tension plates, and the third thread tension device 14 supplies the yarn. Tension is applied to the sewing thread T fed from the source. The third thread tension device 14 can apply a relatively weak tension to the sewing thread T in accordance with the elastic force inherent to the spring, and functions effectively when finely adjusting the thread tension.

As shown in FIGS. 1 and 4, the fourth thread tension device 15 includes a shaft member 15 a that extends in the upward direction away from the surface side of the sewing machine arm 2 and has a substantially cylindrical shape.
A spiral thread guide groove 15b is formed on the side surface of the shaft member 15a so as to wind the surface.
By winding the sewing thread T along the thread guide groove 15b of the shaft member 15a of the fourth thread tension device 15, the sewing thread T comes into sliding contact with the peripheral surface of the shaft member 15a and the thread guide groove 15b. The fourth thread tension device 15 applies tension to the sewing thread T fed from the thread supply source.
The fourth thread tension device 15 applies tension to the sewing thread T based on the frictional force when the sewing thread T slides on the thread guide groove 15b and the force by which the sewing thread T winds and squeezes the shaft member 15a. The tension applied to the sewing thread T can be adjusted according to the length of the sewing thread T that is in sliding contact with the thread guide groove 15b. That is, the fourth thread tension device 15 applies a higher tension to the sewing thread T as the sewing thread T is wound around the shaft member 15a along the thread guide groove 15b, and decreases the winding speed. A low tension is applied to the sewing thread T.

As shown in FIGS. 1 and 4, the bobbin winding device 16 includes a bobbin winding shaft 16 a protruding outside the sewing machine arm 2, a bobbin winding lever 16 b as an operation unit for switching between rotation and stop of the bobbin winding shaft 16 a, A thread winding shaft 16a and a base 16c for holding the thread winding lever 16b on the sewing machine arm 2 are provided.
A lower end portion of the bobbin winding shaft 16a is disposed inside the sewing machine arm 2, and a bobbin wheel (not shown) is fixed to the lower end portion of the bobbin winding shaft 16a. This bobbin wheel (not shown) can be moved toward and away from a bobbin driving mechanism (not shown) by operating the bobbin winding lever 16b.
Then, when the unillustrated bobbin wheel comes into contact with an unillustrated bobbin driving mechanism (for example, the upper shaft of the sewing machine), the driving of the bobbin driving mechanism is transmitted to the bobbin winding shaft 16a, and the bobbin winding shaft 16a Rotate around an axis.
That is, by attaching the bobbin B to the upper end side of the thread winding shaft 16a on the base 16c and rotating the thread winding shaft 16a, the sewing thread T is wound around the bobbin B as the thread winding shaft 16a rotates. ing.
The configuration and operation of the bobbin winding device 16 are the same as those conventionally known and will not be described in detail here.

When the thread winding device 16 is operated to rotate the thread winding shaft 16a, the fourth thread is used when the sewing thread T is unwound from a thread supply source (not shown) and wound around the bobbin B. A desired yarn tension can be applied to the sewing thread T by the tension device 15.
That is, by increasing the number of turns of the sewing thread T wound around the shaft member 15a of the fourth thread tension device 15, high tension is applied to the sewing thread T, and the sewing thread T is tightly wound around the bobbin B. Further, by reducing the number of windings, it is possible to apply a low tension to the sewing thread T, and to loosely wind the sewing thread T around the bobbin B.

As described above, the fourth thread tension device 15 can easily adjust the thread tension in a wide range from a small thread tension to a large thread tension by adjusting the number of turns of the sewing thread T wound around the shaft member 15a. Can do.
Then, by adjusting the thread tension by adjusting the number of turns of the sewing thread T wound around the shaft member 15a of the fourth thread tension device 15, the sewing thread T is tightly wound around the bobbin B in the sewing machine 1. Can be easily switched to wind loosely.

The present invention is not limited to the above embodiment.
For example, as shown in FIG. 5, the first thread tension that applies tension to the upper thread T by sandwiching the upper thread T supplied from a thread supply source (not shown) by a pair of thread tension plates. In a sewing machine 1a provided with a device 4 and a fifth thread tension device 17, a shaft having a substantially cylindrical shape is formed on the sewing machine arm 2 in the thread path between the first thread tension device 4 and the fifth thread tension device 17. You may make it provide the 6th thread tension apparatus 25 which has the member 25a and the helical thread | yarn guide groove 25b formed so that the side surface surrounding surface of the shaft member 25a may be wound.
The sixth thread tension device 25 also applies tension to the upper thread T based on the frictional force when the upper thread T slides into contact with the thread guide groove 25b and the force by which the upper thread T winds and squeezes the shaft member 25a. The tension applied to the upper thread T can be adjusted according to the length of the upper thread T that is in sliding contact with the thread guide groove 25b.
In the sewing machine 1a, the sixth thread tension device 25 adjusts the upper thread T so as to apply a wide range of thread tension from a small thread tension to a large thread tension, and the first thread tension device 4 and the fifth thread tension device 4 By finely adjusting the thread tension with the thread tension device 17, it is possible to easily switch between a state in which the upper thread T is fed out in the sewing machine 1 a suitable for a thin object and a state suitable for a thick object.

In the above embodiment, there is one thread guide portion on which the upper thread T is hung on the thread take-up spring 51 provided in the second thread tension device 5 (see FIGS. 2 and 3). As shown in FIG. 6, a thread take-up spring 51a having a plurality of (four places in FIG. 6) thread guide portions 51b... Along the axial direction of the shaft member 5a of the second thread tension device 5 is provided. You may make it prepare.
The yarn take-up spring 51a includes a plurality of yarn guide portions 51b, so that the yarn guide portion at a position where the upper yarn T is suitably guided according to the number of turns of the upper yarn T wound around the shaft member 5a. The upper thread T can be hung on the 51b, and the upper thread T is fed out suitably.

  Further, in the above embodiment, as shown in FIG. 7A, the shaft member 5a (15a, 25a) is disposed so as to extend in a direction away from the surface side of the sewing machine arm 2. However, the present invention is not limited to this, and as shown in FIG. 7B, the shaft member 35a is arranged in a direction along the surface of the sewing machine arm 2 (for example, substantially parallel to the surface of the sewing machine arm 2). (Direction along) may be extended.

Moreover, the shape of the shaft member 5a (15a, 25a) and the yarn guide groove 5b (15b, 25b) is not limited to the present embodiment, and may be any shape.
For example, as shown in FIG. 8 (a), the shaft member 55a may have a thread guide groove 55b that rotates twice on its peripheral surface, and as shown in FIG. 8 (b), the shaft member 65a. May have a thread guide groove 65b that rotates once on its peripheral surface.
Further, as shown in FIG. 8 (c), the shaft member 55a (65a) has a thread guide groove 75b that rotates twice on the peripheral surface of the shaft member 75a having a different length, or as shown in FIG. 8 (d). As described above, the shaft member 75a may have a thread guide groove 85b that rotates once on the peripheral surface of the shaft member 85a having a diameter different from that of the shaft member 75a.
In this way, by changing the length of the shaft member, the thickness of the diameter of the shaft member, the number of turns and the pitch of the spiral shape of the yarn guide groove formed in the shaft member, the sewing thread that is in sliding contact with the yarn guide groove can be made. Since the acting frictional resistance is different, the shaft member and the thread guide groove may be formed in various shapes so as to have a frictional resistance corresponding to a desired thread tension.

Also, the cross-sectional shape of the shaft member is arbitrary, and is not limited to a circular shape, but may be an elliptical shape or a polygonal shape. The frictional resistance acting on the sewing thread that is in sliding contact with the shaft member and the thread guide groove can also be switched depending on the cross-sectional shape of the shaft member.
Further, the shaft member is not limited to a linear bar shape, and may be a curved shape or an arcuate shape that is bent according to the direction in which the sewing thread is guided.

  Further, the depth and shape of the yarn guide groove are also arbitrary, and any shape may be used as long as the sewing yarn is suitably slid and fed out.

  Further, the spiral shape of the thread guide groove may be either right-handed (right-handed) or left-handed (left-handed). For example, in the case of the shaft member 5a of the second thread tension device 5, the shaft The upper thread T may be wound from the sewing machine arm 2 side of the member 5a toward the distal end side, or the upper thread T is wound from the distal end side of the shaft member 5a toward the base end of the sewing machine arm 2 side. May be.

  In addition, it is needless to say that other specific detailed structures can be appropriately changed.

It is a perspective view showing a sewing machine provided with a thread tension device concerning the present invention. It is a perspective view which shows the thread tension device and balance vicinity which concern on this invention. It is a partial cross section side view showing the thread tension device concerning the present invention. 1 is a perspective view showing the vicinity of a thread tension device and a thread winding device according to the present invention. It is a perspective view which shows other embodiment of the thread tension device which concerns on this invention. It is a partial cross section side view showing the thread tension device concerning the present invention. It is explanatory drawing regarding the extension direction of the shaft member of the thread tension device which concerns on this invention, and is extended in the substantially parallel direction with respect to the shaft member (a) extended from a sewing machine arm in a substantially perpendicular direction, and the surface of a sewing machine arm. It is a shaft member (b). It is explanatory drawing which shows the modification of the shaft member of the thread tension device which concerns on this invention, and a thread guide groove, The thread guide groove (a) which rotates the surrounding surface of a shaft member twice, The thread | yarn which rotates the surrounding surface of a shaft member 1 time A guide groove (b), a thread guide groove (c) that rotates twice on the peripheral surface of the short shaft member, and a thread guide groove (d) that rotates once on the peripheral surface of the short and thick shaft member.

Explanation of symbols

1, 1a sewing machine 2 sewing machine arm 3 balance 5 second thread tension device (thread tension device)
5a Shaft member 5b Thread guide groove 15 Fourth thread tension device (thread tension device)
15a Shaft member 15b Thread guide groove 25 Sixth thread tension device (thread tension device)
25a Shaft member 25b Thread guide groove 51, 51a Thread take-up spring 10 Needle bar 12 Sewing needle 12a Needle hole 16 Thread winding device 16a Thread winding shaft 16b Thread winding lever 16c Foundation T Upper thread (sewing thread)

Claims (2)

A shaft member extending in a predetermined direction;
A spiral thread guide groove formed so as to wind the peripheral surface of the shaft member,
A thread tension device for a sewing machine, wherein tension is applied to the sewing thread by sliding contact resistance of the sewing thread guided in the thread guide groove.   The thread guide groove is formed so as to wind the circumferential surface of the shaft member a plurality of times, and the sewing thread is wound on the shaft member along the thread guide groove according to the number of turns. 2. The thread tension device for a sewing machine according to claim 1, wherein tension applied to the yarn is adjusted.

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