JPH0214773Y2 - - Google Patents

Description

[Detailed description of the invention] [Subject of the invention] This invention relates to a fixed blade for a thread trimming sewing machine.

[Prior art]

In conventional thread trimming sewing machines, a movable blade that rotates back and forth above the hook of the sewing machine after sewing is finished.
During the reciprocation, the thread was caught by the thread guide portion, and after the thread rotated while coming into contact with the fixed blade and being squeezed, the thread was cut between the fixed blade and the movable blade.

That is, as shown in FIG. 1, the movable blade 1 rotates clockwise to capture the upper and lower threads 2 and 3. Then, the rotation is further continued, and in order to secure the amount of thread pulled out from the needle 4 and hook 5 required after thread cutting is completed, the second to third As shown in the figure, the blade portion 1b of the movable blade meshes with the blade portion 6a of the fixed blade 6. There, the upper and lower threads 2 and 3 were cut, and then the movable blade 1 was moved back to its original standby position by a spring means (not shown).

[Problems with the prior art and technical analysis thereof] In the prior art, both the upper and lower yarns near the second diagram are pulled while in contact with the blade portion 6a of the fixed blade 6. This blade part 6a has an acute angle shape as shown in FIG. 4, so the thread is squeezed at this part,
There was an inconvenience that it was torn off. This phenomenon occurs before thread cutting occurs at the normal timing.

Therefore, the remaining length of thread from the fabric or needle to the cutting point becomes shorter, and the upper thread may come out of the needle due to the pull-up action of the thread take-up at the start of the next sewing, or the amount of thread protruding from the bobbin case is still small. There was a drawback that the upper thread could not catch the lower thread, making sewing impossible.

Technology to cover this drawback (Special Publication No. 53-37781
No.), but in this technique, the sewing thread still comes into contact with the cutting edge of the fixed blade, but the contact angle is simply increased. Therefore, if there are differences in the type of yarn used, the yarn count, etc., it is impossible for all of them to cover up the drawbacks of the conventional yarn under the same conditions.

In addition, this technique requires a complicated structure, which has disadvantages in terms of manufacturing, labor for assembling and adjusting additional parts, and increased costs.

[Technical issues]

The object of the present application is to solve the various problems that occurred in the conventional products by simply improving the thread trimming fixed blade.

[Technical Means] As a solution to the above-mentioned problem, the present invention provides a plate-like thread guide member that extends forward from the cutting edge of a fixed blade and has a U-shaped thread guide portion, and is mounted on the fixed blade so that its mounting position can be adjusted back and forth. It is installed integrally.

[Effect of technical means]

The pulling force of the suture thread is entirely received by the guide portion of the thread guide member, and the thread is not directly squeezed by the blade portion of the fixed blade. Even if the sewing thread were to come into contact with this cutting edge for some reason, the straining force it would receive would be minimal and would not cause any trouble.

[Special effects produced by the present invention]

The attachment position of the thread guide member on the fixed blade can be adjusted, and the sewing thread that contacts the cutting edge of the fixed blade is slightly worn, so that the fixed blade tip will not be twisted and cut before the normal cutting timing. . Further, the movable blade captures the upper and lower threads and performs a rapid unwinding action (near FIGS. 2 and 3), but at this time, the bobbin 7 that holds the lower thread idles due to inertia. In such a case, problems such as the bobbin thread unraveling and protruding from the bobbin case 8 may occur. At this time, the thread guide member of the present invention uses its spring action to soften the shock applied to the bobbin 7, thereby preventing the occurrence of the above-mentioned inconvenience. Also,
The U-shape of the thread guide member guides the sewing thread in a predetermined direction by the guide portion, preventing the sewing thread from coming off the cutting edge of the fixed blade, thereby preventing cutting errors.

〔Example〕

In Figs. 5 to 7, reference numeral 6 denotes a fixed blade which is fixed in place on the bed by screws 9. Reference numeral 10 denotes a bullet plate thread guide member, which has a U-shaped thread guide portion 10a with a rounded surface on one end and a long hole 10b on the other end. And, this thread guide member 10 has its thread guide portion 10
a extends forward from the cutting edge 6a of the fixed blade 6, and is attached to the fixed blade 6 with a screw 11 so that its position in the front and rear direction can be adjusted.

Therefore, the clearance between the sewing thread and the cutting edge 6a of the fixed blade can be kept at a suitably small level, and the U-shaped guide portion can prevent the thread running direction from being disturbed.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams explaining the structure and operation of the automatic thread trimming device. Figure 4 is a diagram explaining the conventional sewing thread feeding state. Figure 5
The figure is a side view of the vicinity of the fixed blade of the present invention, Figure 6 is a side view showing the state when there is thread near the fixed blade of the present invention, and Figure 7 is an exploded perspective view of the vicinity of the fixed blade of the present invention. be. 1...Moving blade, 6...Fixed blade, 10...Thread guide member.

Claims (1)

[Scope of utility model registration request] In a thread trimming sewing machine equipped with a movable blade that reciprocates in a circular arc on the center of the lower shaft and engages with a fixed blade in the upper space of the hook during forward movement to cut the sewing thread, the blade portion of the fixed blade is attached to the upper surface of the fixed blade. A fixed blade for a thread trimming sewing machine, in which a thread guide member having a U-shaped guide part protruding forward is attached to the thread guide member so that its position can be adjusted in the front and back direction.