JPH02132Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) The present invention relates to a feed dog for a thread trimming sewing machine, and is particularly useful for use in a feed dog for a needle-feed type sewing machine.

(Prior art) Conventionally, as this type of device for a thread trimming sewing machine, for example, there is
The technique described in the specification of No. 14581 is known.

In the technology of this kind of thread trimming device, generally, as shown in Fig. 2, the thread trimming signal is turned on at the end of sewing.
As a result, the movable blade 1 rotates clockwise to thread the upper thread 2,
Capture the bobbin thread 3. Then, the movable blade 1 rotates further, and in order to secure the remaining length of each of the upper and lower yarns required after cutting the yarn, the movable blade 1 pays out both yarns in the U-shaped groove 1a of the movable blade, and as shown in FIGS. As shown, the blade portion 1b meshes with the blade portion 6a of the fixed blade 6. There, the upper and lower threads are cut, and the movable blade 4 is configured to return to its original standby position.

(Problem to be solved by the invention) However, both the upper and lower threads near the timing shown in FIG.
It is pulled while in contact with the

In particular, in the conventional device, the upper and lower threads and the blade portion 6a are in such a form that they come into sharp contact with each other, resulting in the inconvenience that low-strength threads may be torn off while being squeezed by the blade portion 6a. Therefore, the remaining length of the upper and lower threads is shortened, resulting in a disadvantage that it becomes difficult to start sewing the next stage. Conventional measures taken to overcome this drawback have been accompanied by drawbacks such as an increase in the number of parts and a complicated device configuration. The present invention aims to eliminate the above-mentioned disadvantages through very simple improvements.

[Structure of the idea]

(Means for solving the problem) The above problem was solved in the present invention by the following means. That is, a protrusion is provided around the needle hole on the back side of the feed dog, so that the angle at which both the upper and lower threads are pulled during the thread cutting operation is inclined toward an obtuse angle with respect to the fixed blade.

(Function) Referring to Fig. 1, the movable blade (not shown)
Both the upper and lower yarns 2 and 3 are let out in the U-shaped groove of
Push-back resistance is received by a protrusion 12a provided around the outer periphery of the needle hole on the back side of the feed dog 12. The blade portion 6a of the fixed blade 6 is inclined toward the obtuse angle direction. (This tilting effect can be easily understood by comparing and contrasting it with FIG. 5.) (Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

When the thread trimming signal is turned on, the movable blade 1 rotates clockwise in conjunction with the main shaft of the sewing machine, as shown in the second diagram, to capture the upper thread 2 and the lower thread 3. Then, the rotation is continued, and both threads are let out in the U-shaped groove 1a (FIG. 2) of the movable blade 1 in order to secure the required amount of withdrawal from the needle 4 and bobbin 9 after thread cutting is completed. After that,
As shown in FIG. 4, the blade portion 1b of the movable blade 1 engages with the blade portion 6a of the fixed blade 6, and the needle thread 2 and hook thread 3 are cut. Thereafter, the movement is reversed by a spring (not shown) and returned to the standby position.

However, as shown in FIG. 3 described above, the upper and lower threads are pulled through the feed dog 11 while being in contact with the blade portion 6a of the fixed blade 6, so that the state shown in FIG. 5 occurs. Therefore, the upper thread 2 and the lower thread 3 are squeezed by the blade part 6a of the fixed blade 6, and especially when using threads with high resistance, the threads may be strained by the blade part 6a.

As shown in FIG. 1, the present invention provides a protrusion 12a on the outer periphery of the needle hole on the back side of the feed dog 12.
The upper thread 2 and the lower thread 3 either do not come into contact with the cutting edge 6a during the thread cutting operation, or even if they do come into contact with it, it hits at an obtuse angle. This eliminates the inconvenience of not being able to secure the required bobbin thread amount after the thread trimming is completed due to the threads being cut or torn off during the thread trimming operation.

[Effect of idea]

One idea is to shift the position of the fixed blade in order to compensate for the drawbacks seen in the past, but this poses another troublesome problem of adjusting the arrangement with other components and ensuring dimensional accuracy.

In the present invention, the desired purpose can be easily achieved by simply providing a protrusion around the needle hole on the back side of the feed dog without adding any additional parts.

[Brief explanation of drawings]

Figure 1 is an enlarged cross-sectional view of the main parts of the feed dog of the present invention and their functions, Figures 2 to 4 are diagrams of the general configuration of the sewing machine thread cutting device and its functions, and Figure 5 is the configuration of the feed dog in the conventional device. It is an enlarged cross-sectional view for explaining the action. 1...Moving blade, 2...Upper thread, 3...Lower thread, 6...
...Fixed blade, 11...Feed dog (conventional), 12...Feed dog (this application), 12a...Protrusion.

Claims (1)

[Scope of utility model registration request] A needle-feed sewing machine equipped with a fixed blade fixed to the sewing machine bed, and a movable blade that is interlocked with the main shaft of the sewing machine, rotates almost concentrically with the rotation center of the hook, and meshes with the fixed blade to cut the upper and lower sewing threads. In the thread cutting device, the feed dog of the thread cutting sewing machine has a protrusion formed along the periphery of the needle hole on the back side of the feed dog.