JPH11488A - Thread tension guide for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To change the tension of thread even during sewing by providing an adjustment means for adjusting the tension of a first thread tension spring using a first manual control member and a manual control means for preventing the force of a second thread tension spring from being applied to a thread tension plate by using a lever. SOLUTION: A pair of thread tension plates 1, spring stopper 3 having a protrusion 3a which protrudes sideways and coil spring as a first thread tension spring are loosely fitted to a thread tension axis. A gear 5 is screwed in on a protruding end of the thread tension axis. The gear 5 is rotated by the operation of a dial as a manual control member provided on the front face of the sewing machine via a gear assembly. Thus, the gear 5 moves back and forth to adjust the tension of the top thread passing between the thread tension plates 1. One end of a long lever 8 which is rotatably mounted on the axis of the frame 7 of the sewing machine is pressed by a spring 9 against the spring stopper 3. The long lever 8 is detached from the spring stopper 3 by pressing of a lever 11 when a button is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thread tension device for a sewing machine.

[0002]

2. Description of the Related Art As a thread tension device of a sewing machine, a pair of tension discs is provided with a weak conical spring, a receiving tray, a strong conical spring, and an adjusting nut connected in series. While adjusting the spring force of the weak conical spring by moving operation, when sewing a thick cloth, screw in the adjusting nut to increase the spring force of the weak conical spring as much as possible, and then increase it by turning the adjusting nut further. A device that adjusts the spring force of a conical spring is known.

In Japanese Patent Application Laid-Open No. 4-295396, a first thread tension spring for urging the spring receiver is provided on a spring receiver disposed adjacent to the thread tension disc, and a second thread tension spring is provided via a lever. There has been proposed a thread tension device in which a spring is provided, and a lever is separated from a spring receiver in response to a selection operation of a sewing pattern change dial to release the bias of a second thread tension spring.

[0004]

In the former thread tension device described above, the thread tension must be changed by rotating the adjusting nut every time the sewing pattern is changed. On the other hand, in the latter thread tension device, By operating the sewing pattern change dial, the tension of the upper thread automatically changes.Therefore, once the thread tension is set with the thread tension dial, it is necessary to readjust the thread tension even if the sewing pattern changes. There is an advantage that the tension adjustment operation is extremely simple, but the urging of the second thread tension spring cannot be released unless the sewing pattern is a predetermined sewing pattern. , A complicated mechanism such as a lever, a rod, a follower, a cam, and a sewing pattern changing dial for rotating the cam is required.

SUMMARY OF THE INVENTION It is a first object of the present invention to provide a thread tension device for a sewing machine which can be urged or released by a second thread tension spring at any time. To provide a thread tension device of
The purpose of.

[0006]

A thread tension device for achieving the first object is a thread tension shaft fixed to a sewing machine frame, a pair of thread tension discs loosely fitted to the thread tension shaft, a spring receiver, and a thread tension shaft. 1 thread tension spring, and a first manual operation member such as a dial.
Adjusting means for adjusting the spring force of the thread tension spring, a lever,
A second thread tension spring that urges the lever in one rotation direction to press a part of the lever against a spring receiver, and a second manual operation member that can be operated independently of selection of a sewing pattern And a manual operation means for rotating the lever against the action of the spring and separating the lever from the spring receiver.

[0007] According to the present invention, when it is desired to reduce the tension pressure, for example, when performing thin fabric or buttonhole sewing, the biasing by the second thread tension spring can be released by operating the second manual operation member. Also, arbitrarily the second during sewing
The thread tension can be changed by operating the manual operation member.
A thread tension device for achieving the second object is characterized in that a cam, a wedge, a link mechanism, or the like, which is connected to a second manual operation member and engages with the lever, is used as manual operation means of the device. I do.

[0008]

1 and 2, a thread tension shaft (not shown) fixed to a sewing machine frame is provided with a pair of thread tension discs 1 and a protruding piece 3a protruding laterally. Spring receiver 3
And a coil spring 4 as a first thread tension spring are loosely fitted, and a gear 5 is screwed to a projecting end of the thread tension shaft. The gear 5 is connected to a dial 6 (FIG. 1) serving as a first manual operation member provided on the front surface of the sewing machine via a gear transmission mechanism (not shown). While moving back and forth along the thread tension axis, the tension of the upper thread passing between the thread tension discs 1 can be adjusted.

A long lever 8 pivotally attached to the sewing machine frame by a shaft 7 is acted by a spring 9 as a second thread tension spring so that one end of the long lever 8 presses the spring receiver 3, and the spring 9 is operated by manual operation means. , And one end thereof is separated from the spring receiver 3 so that the action of the spring 9 does not reach the thread tension disc 1. The manual operation means of the present embodiment includes a lever 11, a rod 13 having a shooting 12 as a second manual operation member, a link 14 which is passed through the end of the lever 11 and connects the lever 11 and the rod 13, A spring 15 for urging one end of the lever 11 in a direction to separate the lever 11 from the long lever 8 is provided.
3, the lever 9 is pushed in against the action of the spring 9 to push one end of the long lever 8 into the spring receiver 3.
Let go more.

In another embodiment, the manual operation means comprises a dial and a cam fixed to the dial shaft and engaged with the long lever 8, and the long lever is pushed by the cam which is rotated by rotating the dial. A push button, and a wedge that is integrated with the push button and engages with the long lever 8, and is configured to push the long lever by pushing the push button.

In this embodiment, when performing zigzag stitching, as shown in FIGS. 1 and 3, the coil spring 4 and the spring 9 act on the thread tension plate 1 while the shooting 12 is raised, and the set pressure is reached. When performing buttonhole sewing, sewing a thin material, or when wanting to make a weak tension, the photographer 12 is depressed, and the long lever 8 is
And one end thereof is separated from the spring receiver 3 so that only the coil spring 4 acts on the thread tension disc 1 so that the tension is weak.

In the figure, reference numeral 17 denotes a short lever which is attached to the shaft 7 together with the long lever 8 and which is turned via a lever 19 by operating a press-up lever 18 to push the protruding piece 3a of the spring receiver 3 into place. The spring receiver 3 is tilted so that the action of the coil springs 4 and 9 does not reach the thread tension disc 1. That is, when the presser lifting lever 18 is rotated prior to sewing,
The presser foot is lifted onto the needle plate, and the presser against the thread tension plate is released to facilitate threading.

[0013]

According to the first aspect of the present invention, the thread tension by the first thread tension spring does not need to be changed regardless of what sewing pattern is selected or during sewing. The tension can be arbitrarily biased by the second thread tension spring or released according to the above, and the tension can be switched between strong and weak.

According to the second aspect of the present invention, since the manual operation means comprises one of the second manual operation member and a cam, a wedge or a link mechanism connected to the second manual operation member, The operating means is a second manual operating member,
The structure is simpler than having a cam and a link mechanism.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of a sewing machine provided with a thread tension device.

FIG. 2 is a plan view of the same.

FIG. 3 is a view showing manual operation means when a spring acts.

FIG. 4 is a plan view of a main part of the sewing machine when the action of the spring is released.

FIG. 5 is a view showing the manual operation means.

[Explanation of symbols]

 1. Thread tension plate 3. Spring holder 3a Projection piece 4. Coil spring 5. Gear 6. Dial 7. Shaft 8. Long lever 9. Spring 11. Lever 12. Shooting 13 ・ ・ Rod 14 ・ ・ Link 15 ・ ・ Spring 17 ・ ・ Short lever 18 ・ ・ Presser lift lever 19 ・ ・ Lever

Claims (2)

[Claims] 1. A thread tension shaft fixed to a sewing machine frame, a pair of thread tension discs loosely fitted on the thread tension shaft, a spring receiver, a first thread tension spring, and a first manual operation member such as a dial. Including
Adjusting means for adjusting the spring force of the first thread tension spring; a lever; a second thread tension spring for urging the lever in one rotation direction to press a part of the spring against a spring receiver; A second manual operation member that can be operated independently of the selection of the pattern, wherein the lever is turned against the action of the spring,
A thread tension device for a sewing machine, comprising: manual operation means for separating from a spring receiver. 2. The thread tension device of a sewing machine according to claim 1, wherein the manual operation means is a cam, a wedge, a link mechanism or the like which is connected to the second manual operation member and engages with the lever.