JP2876800B2 - Sewing machine upper thread adjusting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upper thread adjusting device for adjusting the condition of an upper thread such as a household sewing machine and an industrial sewing machine.

[0002]

2. Description of the Related Art As a prior art relating to a device for adjusting the upper thread tension of a sewing machine, there is known an upper thread adjusting device disclosed in Japanese Utility Model Publication No. 40-28041. In this needle thread adjusting device, as shown in FIG. 4, a weak conical spring 1, a receiving tray 2, and a strong conical spring 3 are superposed above a pair of tone plates 5, and the upper end of the strong conical spring 3 is adjusted. The nut 4 is biased downward. According to this needle thread adjusting device, when the adjusting nut 4 is rotated and urged downward, the weak conical spring 1 is first urged, and the weak conical spring 1 is compressed to reach the limit. The rear strong conical spring 3 is urged. When sewing a thin cloth, a weak adjustment is easily performed in a wide range where the weak conical spring 1 is urged, and when a thick cloth is sewn, a strong adjustment is made. The narrow and strong adjustment in which the conical spring 3 is biased can be performed precisely.

[0003] In general, even when sewing the same fabric, the thread condition must be changed according to the sewing pattern.
However, in the conventional example, every time the sewing pattern is changed, the adjusting nut 4 must be rotated to adjust the thread tension, which is troublesome.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a sewing machine in which the condition of the upper thread is automatically changed without the user changing the condition of the upper thread according to the change of the sewing pattern. It is an object of the present invention to provide a needle thread adjusting device.

[0005]

Configuration of the Invention

[0006]

In order to solve the above-mentioned problems, the technical solution taken in the present invention is a thread tension shaft fixed to a machine frame, and a pair of threads loosely fitted to the thread tension shaft. A tension disc, a spring receiver which is loosely fitted to the thread tension shaft adjacent to the thread tension disc, and has a flange on its outer periphery; and a first thread loosely fitted to the thread tension shaft adjacent to the spring receiver. A tone spring and the first
A first pressing unit that presses the thread tension spring toward the thread tension disc; a tension balance that is pivotally supported by the machine frame so that one end can contact the collar; and the tension balance attached to the collar. A second thread tension spring that constantly presses in the contacting direction, a second pressing unit that urges the second thread tension spring in a direction opposite to the second thread tension spring to release the pressure on the collar, and a second thread tension spring. An upper thread adjusting device for a sewing machine comprising a sewing pattern designating means connected to the sewing pattern designating means to selectively urge the second pressing means in the opposite direction to the second thread tension spring at the same time as designating the sewing pattern.

[0007]

The above-mentioned problem operates as follows. First, in the case of normal sewing such as straight stitching, the thread tension disc is urged from both the first thread tension spring and the second thread tension spring via a spring receiver, and the fine thread tension is pressed by the first pressing means. It is getting adjusted. Next, in the case where the selected pattern is a pattern requiring lowering of the needle thread tension such as close stitching, the user operates the sewing pattern designating means to change the sewing pattern and, at the same time, changes the sewing pattern designating means. Biases the second pressing means in a direction opposite to that of the second thread tension spring. For this reason, the urging force of the second thread tension spring does not act on the spring receiver, and the thread tension disc is pressed by the urging force of only the first thread tension spring, and the force with which the thread tension disc presses the upper thread is weakened. In this way, the needle thread tension is changed at the same time the user selects the sewing pattern,
There is no need for the user to change the condition of the upper thread of the sewing machine according to the change of the sewing pattern.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a sewing machine 10 provided with a needle thread adjusting device according to the present embodiment. The sewing machine 10 has an external appearance constituted by a machine frame 11, and includes an arm bead 10a having a sewing work surface on an upper surface, a sewing machine leg 10b standing upright from the arm bead 10a, and horizontally extending from the sewing machine leg 10b. An arm head 10c is provided. Sewing machine leg 1
On the side of 0b, a sewing pattern change dial 12 is rotatably arranged. By rotating the sewing pattern change dial 12, the user can perform buttonhole sewing, straight line sewing, zigzag sewing, and the like as displayed on the display panel 13.
Several types of sewing patterns, such as close stitching, can be selected.

On the upper surface of the arm head 10c, a thread pin 14 on which a thread winding of a sewing thread is arranged is fixed. The sewing thread is wound up from the thread pin 14 through the groove 15 via the convex portion 16, turned again by the convex portion 17 and lowered downward, and then inserted into a hole of a sewing needle (not shown). It has become to be. The groove 15 contains a pair of thread tension discs 21 (FIG. 2) described later, and the sewing thread passing through the groove 15 is sandwiched between the thread tension discs 21. By moving the thread tension dial 25 protruding from the upper surface of the arm head 10c to the right or left, the thread tension disc 21 comes into strong or weak contact so that the thread tension of the upper thread can be adjusted.

Next, the upper thread adjusting device 20 will be described with reference to FIG. FIG. 2 is an exploded view of the upper thread adjusting device 20 of the present embodiment. Machine frame 1 of arm head 10c
A mounting plate 29 is provided inside 1, and one end of a thread tension shaft 28 extending substantially parallel to the sewing machine head 11 c is fixed to the mounting plate 29. A pair of thread tension discs 21, a spring receiver 22, a first thread tension spring 23, and an adjustment plate 24 are loosely fitted to the thread tension shaft 28 in this order from the mounting plate 29 side.

The thread tension plate 21 includes a first thread tension plate 21a provided on the mounting plate 29 side and a second thread tension plate 21b loosely fitted on a thread tension shaft 28 adjacent to the first thread tension plate 21a. Consisting of The upper thread is always disposed so as to pass between the first thread tension plate 21a and the second thread tension plate 21b, so that the thread tension is adjusted by being sandwiched between two thread tension plates. The spring receiver 22, which is loosely fitted adjacent to the thread tension plate 21, has a collar 22a formed at the center. A protrusion 22b is formed at one end of the spring receiver 22. The protruding portion 22 b protrudes in the axial direction of the spring receiver 22 and presses the inner peripheral portion through which the upper thread of the thread tension disc 21 passes. Thus, thread tension plate 2
1 can efficiently clamp the upper thread. At the other end of the spring receiver 22, a first cylindrical portion 22c protruding from the central portion along the thread tension shaft 28, and a first cylindrical portion 2c.
2c which protrudes in the axial direction at a certain interval from 2c
2d is formed. The first thread tension spring 23 has a concave portion 22 formed between the first cylindrical portion 22c and the second cylindrical portion 22d.
e.

The other end of the first thread tension spring 23 has an adjusting plate 24
Is loosely fitted. The adjusting plate 24 is a left loose fitting portion 24a that abuts on the first thread tension spring 23, a plate portion 24b extending from the left loose fitting portion 24a in parallel with the thread tension shaft 28, and is bent perpendicularly to the plate portion 24b. It is composed of a right play fitting portion 24c and a contact finger 24d protruding in the axial direction from the right play fitting portion 24c. In the center of the left loose fitting portion 24a and the right loose fitting portion 24c, holes a,
The thread tension shaft 28 is inserted through the holes a and c. The plate portion 24b is provided with an elongated hole portion 24e extending in the axial direction. Guide pins 26 fixed to the machine frame are inserted into the elongated holes 24e, and regulate the adjustment plate 24 so as not to blindly move in the circumferential direction of the thread tension shaft 28. A thread tension dial 25 is pivotally supported adjacent to the adjustment plate 24. The thread tension dial 25 includes an operation portion 25a that projects a part of the circumference from the machine frame 11, an eccentric portion 25b formed on the front surface of the operation portion 25a, and a hole 25c that penetrates the operation portion 25a and the eccentric portion 25b. Become. The hole 25c is formed at the center of the operation unit 25a, and the eccentric portion 25b
Is off center. The sliding portion 27a of the receiving screw 27 is inserted into the hole 25c, and a male screw portion 27b formed at the tip of the receiving screw 27 is formed.
Is screwed into the machine casing 11 to thereby make the thread tension dial 2
5 is rotatably supported by the machine frame 11. The thread tension dial 25 works together with the first thread tension spring 24 as a first pressing member that presses the spring receiver 22.

Next, a mechanism for pressing the spring receiver 22 in conjunction with the sewing pattern changing dial 12 will be described. The tension scale 30 disposed below the spring receiver 22 has an abutting portion 30b at one end abutting against a brim portion 22a of the spring receiver 22. A cylindrical portion 30a is provided at the center of the tension balance 30, and a sliding portion 32a of a screw 32 is inserted into the cylindrical portion 30a. Like the receiving screw 27, the screw 32 fixes the tension balance 30 to the machine frame so as to be rotatable. One end of a second thread tension spring 31 is locked to the other end of the tension balance 30, and the other end of the second thread tension spring 31 is fixed to the machine frame 11.
The second thread tension spring 31 urges the tension balance 30 in a direction for rotating the tension balance 30 in a counterclockwise direction. One end of a tension switching connecting rod 33 is locked between the cylindrical portion 30a and the contact portion 30b of the tension needle 30. The other end of the tension switching rod 33 is connected to a switching weigher 34 rotatably supported by a machine frame by a screw member (not shown).
At one end. The switching scale 34 is rotatable about a hole 34b formed in the center. Since the second thread tension spring 31 urges the tension balance 30 in the counterclockwise direction, one end of the tension switching connecting rod 33 is
The switching weigher 34 is also urged to rotate in the counterclockwise direction. Accordingly, the contact portion 34a at the other end of the switching scale 34 comes into contact with the outer peripheral surface 35b of the switching cam 35. The switching cam 35 is connected to the sewing pattern changing dial 12 by a connecting member (not shown), and rotates around the hole 35 a in conjunction with the rotation of the sewing pattern changing dial 12. On the outer peripheral surface 35b of the switching cam 35, a convex portion 35c is formed. In this embodiment, when the sewing pattern change dial 12 indicates the close stitching, the convex portion 35c comes into contact with the contact portion 34a of the switching scale 34.

Next, the operation of this embodiment will be described. In the case of normal sewing such as straight stitching, the spring receiver 22 is urged toward the thread tension disc 21 by both the first thread tension spring 23 and the second thread tension spring 31. The fine adjustment of the thread tension can be adjusted by rotating the thread tension dial 25.
When the thread tension dial 25 is rotated, the hole 25
This is because the distance from c to the outer periphery of the eccentric portion 25b changes, and the pressing force for pressing the contact finger 24d toward the first thread tension spring 23 can be changed. As a result, the upper thread can obtain a tension as shown by a solid line 41 in FIG. At this time, the contact portion 3 of the switching scale 34
4a is in contact with the peripheral surface of the switching cam 35 which is not the convex portion 35c.

Next, the case of performing the close stitching will be described. Close stitching refers to a method in which the first and third stitches or the stitch between the second and fourth stitches are narrow in zigzag stitching. It is necessary to reduce the tone.
First, when the user operates the sewing pattern change dial 12 to specify the close stitching, the sewing pattern change dial 12 operates the upper shaft and the lower shaft (not shown) to perform the close stitching, thereby changing the cloth feed amount and the like. . At the same time, the switching cam 35 is rotated by a connecting member (not shown), and the convex portion 35c is moved to the switching scale 34.
Is brought into contact with the contact portion 34a. The convex part 35c is a switching scale 34.
Is urged in the clockwise direction, the tension scale 30 is also urged clockwise via the tension switching connecting rod 33. As a result, the contact portion 30b of the tension scale 30 is connected to the flange portion 2 of the spring receiver 22.
Move away from 2a. Therefore, the spring receiver 22 does not receive the urging force of the second thread tension spring 31 and receives only the urging force of the first thread tension spring 23. At this time, the upper thread is
The tension as shown by the solid line 42 is obtained, and the tension 41 when the thread tension plate 21 is urged by the urging forces of both the first thread tension spring 22 and the second thread tension spring 31 is obtained.
The tension 43 is maintained at a small tension.

As described above, according to the present embodiment, the tension of the upper thread is automatically changed by operating the sewing pattern changing dial 12, so that once the thread tension is set with the thread tension dial 25, the thread tension can be set. Even if the sewing pattern changes, it is not necessary to readjust the thread tension, and the tension adjustment operation can be made extremely simple. Further, there is a limit to the tension range that can be accommodated by one thread tension spring, but the tension regulation range can be expanded by using two thread tension springs. Further, since the first thread tension spring 23 and the second thread tension spring 31 are disposed in parallel, the respective functions can be operated without interfering with each other, unlike the related art.

In this embodiment, the switching cam 35 is provided with a convex portion 35.
Although an example in which only one c is provided is shown, several projections 35c may be provided according to the sewing pattern, and the height of the projection may be adjusted to adjust the tension in accordance with each sewing pattern with the second thread. Tone springs can also be provided.

[0018]

According to the present invention, by operating the sewing pattern change dial, the tension of the upper thread automatically changes, so that once the thread tension is set with the thread tension dial,
Even if the sewing pattern changes, there is no need to readjust the thread tension,
The tension adjusting operation can be made extremely simple.

[Brief description of the drawings]

FIG. 1 is a perspective view of a sewing machine according to an embodiment of the present invention.

FIG. 2 is an exploded view of the upper thread adjusting device of the sewing machine of the present invention.

FIG. 3 is a graph showing the tension of the upper thread.

FIG. 4 is a sectional view of a conventional upper thread adjusting device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 machine frame 12 sewing pattern change dial (sewing pattern designating means) 21 thread tension disc 22 spring receiver 22a collar 23 first thread tension spring 24 adjustment plate (first pressing means) 25 thread tension dial (first pressing means) 28 Thread tension shaft 30 Tension balance 31 Second thread tension spring 33 Tension switching connecting rod (second pressing means) 34 Switching scale (second pressing means) 35 Switching cam (second pressing means)

Claims (1)

(57) [Claims] 1. A thread tension shaft fixed to a machine frame, a pair of thread tension plates loosely fitted to the thread tension shaft, and a thread tension shaft loosely fitted to the thread tension shaft adjacent to the thread tension plate. A spring receiver having a brim portion, a first thread tension spring loosely fitted to the thread tension shaft adjacent to the spring receiver, and a first pressing for pushing the first thread tension spring toward the thread tension disc. Means, a tension balance that is supported by the machine frame such that one end can contact the collar portion, and a second thread tension spring that constantly presses the tension balance in a direction in which the tension balance contacts the collar portion. A second pressing means for pressing the collar against the second thread tension spring in a direction opposite to the second thread tension spring, and a second sewing means connected to the second pressing means for designating a sewing pattern and simultaneously selecting a second pattern;
A needle thread adjusting device for a sewing machine, comprising a sewing pattern designating means for urging the pressing means in a direction opposite to the second thread tension spring.