JP2594433Y2 - Sewing machine lower thread holding device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION This invention relates to a bobbin thread holding device for a buttonhole sewing machine. More specifically, the bobbin thread that is cut is strongly clamped at the start of sewing and the bobbin thread is weakly clamped after sewing is started. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lower thread holding device for a sewing machine which feeds a lower thread as the cloth advances, prevents upper thread from being pulled out or skipped at the start of sewing, and allows the leading end of the lower thread to be wound into the seam.

[0002]

2. Description of the Related Art A sewing machine is provided with a lower thread holding device for cutting a sewing thread at the end of sewing and holding a lower thread of the cut sewing thread. FIG. 4 is a view showing the lower thread holding device of the buttonhole holing machine. In the drawing, reference numeral 6 denotes a needle plate provided on the needle plate base C, which is formed so as to communicate with the needle plate 6 and the needle plate base C. The needle drop hole 6a and the knife insertion hole 6b are provided.

[0003] Reference numeral 1 denotes a fixed knife having a blade portion 1a installed near the needle drop hole 6a so as to direct the blade edge in the needle drop direction. Reference numeral 3 denotes a holding plate, and the holding plate 3 is disposed so as to overlap the upper part of the fixed knife 1 in the figure so as to sandwich the lower thread between the fixed knife 1 and the fixed knife 1.

[0004] Reference numeral 4 denotes a moving table, which is reciprocatingly rotated as shown by an arrow with the step screw P1 as a fulcrum, and driving means (not shown) via a link mechanism A. (A thread trimming lever operated by depressing a work clamp lifting pedal).

The link mechanism A includes a link rod 13 which moves vertically in the figure by driving means, and a step screw 12a.
A pivot link 12 rotatably supported by the link rod 12 and connecting the tip of the link rod 13, and a coupling link 11 having one end connected to the movable base 4 and the bobbin threading arm 5 and the other end to the pivot link 12, respectively. By moving the link rod 13 forward, the rotating link 12 is driven in the counterclockwise direction, the connecting link 11 is moved rightward in the drawing, and the movable base 4 can be moved clockwise. Has become.

On the other hand, reference numeral 5 denotes a lower thread picking arm which is fixed to the moving table 4 with the screw P2 and reciprocates with the moving table 4.
The lower thread picking arm 5 catches the lower thread located between the cloth and the rotary hook (not shown) of the sewing machine, inserts the lower thread between the fixed knife 1 and the holding plate 3 and The lower thread can be pinched. Reference numeral 2 denotes a moving knife having a blade portion 2a fixed to the moving table 4 by a screw P3.
Is reciprocatingly rotated together with the moving body 4 so as to face the moving object 4.

A guide body G is provided at the same height as the blade 2a of the moving knife 2, and guides the lower thread to the fixed knife 1 when the moving body 4 moves. You can do it.

The lower thread holding device of the sewing machine constructed as described above drives the moving table 4 by a thread cutting signal at the end of sewing of the sewing machine. First, the lower thread I is moved by the lower thread picking arm 5 as shown in FIG. It is captured and is held (held) between the fixed knife 1 and the holding plate 3. Next, as shown in FIG. 6, the movable thread 4 is advanced and the lower thread clamped is cut by the cooperation of the fixed knife 1 and the movable knife 2.

After the lower thread is held and cut as described above, the moving body 4 (the lower thread picking arm 5, the moving knife 2) returns to the home position (the state shown in FIG. 4), but is cut. The lower thread is held by the lower thread holding device.
This makes it possible to stabilize the position of the lower thread at the start of the next sewing and to ensure the formation of a stitch with the upper thread.

The lower thread held by the movement of the fabric as the sewing progresses is separated from the lower thread holding device of the sewing machine so as to be pulled out. However, the conventional lower thread holding device of the sewing machine has the following problems. In the lower thread holding device of the sewing machine shown in FIG. 4, when the lower thread used is a thick thread or a thread having a large frictional resistance,
The holding power of the lower thread by the lower thread holding device of the sewing machine becomes strong.

As a result, the lower thread is not properly pulled out of the lower thread holding device during sewing, causing a problem that the cloth to be moved is wrinkled, the seam is displaced, or the cloth is broken. . Further, when the lower thread used is a thin thread, the holding power of the lower thread is weakened, so that the upper thread may easily come off at the start of sewing, or skipping may occur at the start of sewing. In order to solve such inconvenience, a bobbin thread holding device for holding the bobbin thread at the start of sewing and releasing the bobbin thread after the sewing start is used as a bobbin thread 3-7
No. 6576 is disclosed.

This bobbin thread holding device holds a bobbin thread by a moving knife that reciprocates and a clamp member installed in an advance path of the moving knife, and separates the clamp member from the moving knife after sewing is started. Releases the lower thread. According to this bobbin thread holding device, at the start of sewing, the bobbin thread can be properly held, the crossing of the stitch formation with the upper thread can be ensured, and the bobbin thread can be released after the stitch formation. In addition, the movement of the fabric can be made appropriate.

[0013]

However, the above-described sewing machine lower thread holding device also has the following problems.
Since the lower thread holding device of the sewing machine releases the lower thread after the start of sewing, the position of the released lower thread (the tip of the lower thread) is not stable, and the tip of the lower thread does not get caught in the seam. It became uneasy because it protruded from the seam and deteriorated the quality of the sewn product.

[0014]

SUMMARY OF THE INVENTION A lower thread holding device for a sewing machine according to the present invention has been made to solve the above-mentioned conventional problem. Engage with a holding plate that holds so as to pinch,
An object of the present invention is to solve the conventional problem by providing a release arm for reducing the urging force of the holding plate against the fixed knife, and driving the release arm after the next sewing operation is started.

[0015]

The lower thread holding device of the sewing machine according to the present invention holds the lower thread so that the lower stage is moved between the fixed knife and the holding plate by the lower thread take-up arm by moving the movable base when cutting the sewing thread. Then, the lower thread held by the moving knife and the fixed knife is cut, and then the moving table is returned.

After the sewing operation is started, the release arm is driven, and the urging force of the holding plate against the fixed knife is reduced by the release arm. As a result, the lower thread is properly pulled out of the lower thread holding device without hindering the feed movement of the fabric, preventing the upper thread from coming off at the start of sewing or skipping, and forming a lower end of the lower thread than the stitch formed. It can be properly involved so as not to protrude.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. The same parts as in the conventional example are denoted by the same reference numerals, and redundant description will be omitted. FIG. 1 is a view showing a lower thread holding device of a sewing machine. In the drawing, reference numeral 3 denotes a lower thread holding portion 3a which overlaps the fixed knife 1 at one end and holds a lower thread at a second end with a release arm 7 described later. The holding plate has a pressing portion 3b that elastically presses downward from above, and a protruding portion 3c such as a pin or a punch that projects in the horizontal direction is formed near the lower thread holding portion 3a of the holding plate 3. .

Reference numeral 7 denotes a release arm. The release arm 7 extends in the direction of the holding plate 3 and has a protruding portion (engaging portion) 7a protruding upward in the drawing in the vicinity of the protruding portion 3c. A guide 8 having a groove 8a slidably supporting the distal end of the release arm 7 can be moved as indicated by an arrow, and the release arm 7 is normally attached in the direction of the groove 8a by a spring 7b. It is being rushed.

As shown in FIG. 2, normally, the pressing portion 3b is elastically pressed only by the pressing portion 3b and does not contact the other holding plate 3, and the protruding portion 7a is not engaged with the protruding portion 3c of the holding plate 3. It is in. When the release arm 7 moves in the direction of the arrow, the protrusion 7a is engaged with the protrusion 3c on the movement path. The other end of the holding plate 3 is fixed to the needle plate base C together with the guide portion 8 by screws.

The link means B is supported by an operating cam 10 which moves leftward in the figure by a feed mechanism (not shown) and a base 11 which is rotatably attached to a frame by a step screw 9a. The rear end and one end are rotatably connected to each other, and the other end includes a rotation link 9 abutting on the operation cam 10. The feed mechanism moves the operation cam 10 to the left in FIG. By rotating the moving link 9 clockwise, the release arm 7 can be moved rightward.

Although not shown, the operating cam 10 works in conjunction with a known feed mechanism. That is, the movement of the cloth feed arm (lower), which is rotated by the rotational movement on the surface of a cam means (heart cam) that makes one rotation in one cycle, is fixed to the main cam that is interlocked with the main shaft of the sewing machine via a gear or the like. It is linked with the cloth feed table of the feed mechanism via the cloth feed rod via the arm (upper).

An operation cam 10 shown in FIG. 1 is fixed to the cloth feed table with a screw 10a in a slot 10b whose position can be adjusted. Accordingly, when the sewing machine is started by depressing the sewing machine pedal and the sewing is started, the operation cam 10 is activated when the cloth feed amount by the cloth feed table moves to a predetermined set value (for example, 2 mm). The release arm 7 is moved via B.

When the release arm 7 is driven as shown by the arrow, the projection 7a of the release arm 7 engages with the projection 3c of the holding plate 3 as shown in FIG. By moving in the direction away from 1, the urging force on the fixed knife 1, that is, the holding force of the lower thread can be reduced.

The lower thread holding device of the sewing machine constructed as described above moves the movable table 4 clockwise at the end of sewing based on a thread cut signal, and fixes the lower thread by the lower thread picking arm 5 to the lower knife 1. The holding table 3 is held between the moving knife 2 and the fixed knife 1, and the lower thread held by the cooperation of the moving knife 2 and the fixed knife 1 is cut to return the moving table 4 to the home position. At this time, even after the lower thread picking arm 5 is pulled out from between the fixed knife 1 and the holding plate 3, the lower thread remains in the fixed knife 1 and the holding plate 3.
And continue to be held between.

At the start of the next sewing operation, the lower thread is strongly held, and after the sewing operation is started, that is, when the cloth feed amount is moved to a predetermined set value, the release arm 7 is driven to fix the holding knife of the holding plate 3. The urging force (bobbin thread holding force) is reduced. As a result, the lower thread can be pulled out from the lower thread holding device of the sewing machine without hindering the movement of the cloth sent as the sewing progresses, and the leading end of the lower thread is properly wound into the formed seam. It is possible to make it.

In the above embodiment, the release arm 7 is operated by the link means B linked to the feed mechanism. However, a specific rotation angle of the main shaft of the sewing machine using a solenoid or an air cylinder instead of the feed mechanism is used. May be provided, and the release arm 7 may be moved directly by operating a driving means such as a solenoid or an air cylinder in response to a rising signal of a lower detection signal of the first stitch, for example.

[0027]

As described above, the lower thread holding device of the sewing machine according to the present invention engages with the holding plate which overlaps with the fixed knife and holds the lower thread so as to strongly clamp the lower thread, and biases the holding plate against the fixed knife. Release arm is provided, and the release arm is driven after the next sewing is started, so that the lower thread is strongly held at the start of sewing, and the sewing with the upper thread can be performed properly. The upper thread can be prevented from coming off at the start of sewing or skipping at the start of sewing.

After the start of sewing, the holding power of the lower thread is reduced, and the held lower thread is pulled out without hindering the movement of the fabric due to the progress of sewing, and the lower thread can be wound into the seam to be formed. It is possible to stabilize the quality, and productivity is remarkably improved.

[Brief description of the drawings]

FIG. 1 is a bottom view showing a lower thread holding device of a sewing machine according to the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a release arm of the lower thread holding device of the sewing machine shown in FIG. 1 and a holding plate.

FIG. 3 is a perspective view of the lower thread holding device shown in FIG.
It is an operation explanatory view showing a state in which the lower thread holding force of the holding plate for holding the lower thread is reduced.

FIG. 4 is a bottom view showing a configuration state of a lower thread holding device of a conventional sewing machine.

FIG. 5 is an operation explanation showing a state in which a lower thread take-up arm of the sewing machine shown in FIG. 4 allows a captured lower thread to be inserted between a fixed knife and a holding plate and held therebetween. FIG.

6 is an operation explanatory view showing a state in which the moving knife of the lower thread holding device of the sewing machine shown in FIG. 4 cuts the lower thread held in cooperation with the fixed knife.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixed knife 2 Moving knife 3 Holding plate 4 Moving table 5 Lower thread take-up arm 7 Release arm

Claims (1)

(57) [Scope of request for utility model registration] 1. A fixed knife fixed to a needle plate base near a needle drop point of a sewing needle formed on a needle plate so that a cutting edge is directed in a needle drop direction, and a lower thread is held between the fixed knife and the fixed knife. A holding plate that overlaps the fixed knife, a moving table that reciprocates in response to a predetermined thread cutting signal, and a moving table that is fixed to the moving table, catches the lower thread between the fabric and the rotary hook, and moves the fixed knife and the holding plate together. A button provided with a lower thread take-up arm for inserting a lower thread therebetween, and a moving knife fixed to the moving table so as to face the fixed knife via the lower thread take-up arm, and cutting the lower thread with the fixed knife. In a lower thread holding device of a sewing machine in a boring machine, a position of a driving means or a position of a sewing needle which is interlocked when a cloth feed amount of a cloth feed mechanism is moved to a predetermined set value by a rotational movement of a cam means which is interlocked with a main shaft of the sewing machine. Responds to the detection signal output from the detection means. The driving means for operating Te, engaging said holding plate, the release arm to reduce the urging force of the fixed knife of the holding plate is provided, by driving the release arm after the next sewing is started, the cutting Between the fixed knife and the holding plate
At the start of sewing, the lower thread clamped by
After the release arm is driven, the lower thread is
The sewing machine is characterized in that the lower thread connected to the seam is pulled out from the holding plate by the cloth feed as the sewing progresses , so that the tip of the lower thread is wound into the seam formed by the buttonhole. Lower thread holding device.