JPH057038B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for preventing stitch skipping and thread breakage in industrial chain stitch sewing machines.

In this type of sewing machine, the bobbin is located away from the main body of the sewing machine, thereby increasing the distance from the bobbin to the needle of the main body of the sewing machine, allowing the thread to be fed effortlessly and smoothly and preventing thread breakage.

The thread in the thread path between the bobbin and the needle of the sewing machine body is passed through the thread hook in a zigzag pattern.

By the way, since the diameter of the thread is not necessarily uniform, or due to the twist, the thread gets caught or tangled in the thread path. Therefore,
Thread cuts and skipped stitches may occur, and in such cases,
There is a problem in that the drive unit does not stop and continues to operate.

The present invention aims to eliminate such defects of conventional products. That is, when a state where skipped stitches or thread breakage is likely to occur, the driving device of the sewing machine is automatically stopped to prevent skipped stitches or thread breakage.

The basic structure of the present invention to achieve such an object is to provide a thread stand at a position isolated from the sewing machine body, fix a top board above the thread stand, and provide an upright piece on the point board. At the top of this upright piece,
An upper thread hook is provided for passing the thread fed from the bobbin of the thread stand, and below the upper thread hook, there is an operating lever with a thread hook hole at the tip for passing the thread passed through the upper thread hook. Rotatably pivots on the
The mechanism is such that when the thread is tensed beyond a predetermined level, the operating lever rotates due to the tension, contacts the micro switch, and stops the driving device of the sewing machine.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 shows a sewing machine equipped with a skipped stitch and thread breakage prevention device according to the present invention, and in the figure, 1 is a bobbin mounted upward on a thread stand, 2 is an electric sewing machine main body,
The thread a fed out from the bobbin 1 is threaded onto a large number of thread hooks 1.
1, 12, 13, 14, etc., and is supplied to the sewing machine main body 2. Then, a skipped stitch and thread breakage prevention device is disposed at an appropriate location on the thread path, preferably at a location close to the bobbin 1. This will be explained in detail based on FIGS. 2 to 4.

The thread a passes through the through hole 31 from the ceiling plate shown in 3, skips stitches, and is fed out to the thread breakage prevention device a. An upright piece 7 is fixed to the top plate 3, and a lower thread hook 15 is provided at the bottom of this upright piece 7, and an upper thread hook 16 is provided at the upper part. A threading hole 41 is provided at the distal end of the threading hole 41. The through hole 31
The thread a that has been let out is passed from the lower thread hook 15 to the upper thread hook 16, and further passed through the thread hook hole 41 of the operating lever 4, and then passed through the thread hook hole 41 of the actuating lever 4, and then passed through the thread hook hole 41 of the actuating lever 4, and then passed through the thread hook hole 41 of the operating lever 4. The thread hook 11 shown in FIG. Therefore, if the thread a is not drawn out smoothly from the bobbin 1, the tension of the thread a fed into the sewing machine body 2 acts on the operating lever 4. Therefore, the tip of the operating lever 4 moves upward. At that time, the vessel body 6 to which the operating lever 4 is connected
A micro switch 5 is disposed on the surface of the sewing machine, and the micro switch 5 is connected so that the operation of the driving device of the sewing machine main body 2 is stopped when the operating lever 4 comes into contact with the micro switch 5.

In this way, the thread a is approximately V at the front and back of the operating lever 4 so that the operating lever 4 is rotated with a slight tension.
Since it is stretched in a shape of a letter, when a tension above a predetermined value is applied to the thread a, the actuation lever 4 moves due to the tension and comes into contact with the micro switch 5.
The operation of the sewing machine main body 2 is stopped. Note that if a tension of more than a predetermined value is applied to the thread a, the operating lever 4
This is the case when the thread a is caught between the bobbin 1 and the bobbin 1, especially when the thread a fed out from the bobbin 1 is entangled.

In the present invention, the thread passing through the threading hole of the actuating lever is
The actuating lever is bent in a substantially V-shape at the front and rear so that the actuating lever is actuated by a slight tension. Therefore, when skipped stitches or thread breakage occur, that is, when thread is difficult to be smoothly supplied to the sewing machine, the tension of the thread acts on the operating lever, causing the operating lever to move. The movement of this actuating lever causes a micro switch to stop the operation of the sewing machine main body drive device.

Therefore, sewing work can be performed accurately without skipping stitches or thread breakage. Moreover, like conventional products,
Workability is improved because processing steps after stitch skipping and thread breakage are no longer necessary.

[Brief explanation of the drawing]

Fig. 1 is a front view showing a sewing machine equipped with the device of the present invention, Fig. 2 is a partially cutaway front view, Fig. 3 is a sectional view taken along the - line, and Fig. 4 is a partially cutaway side view. FIG. In the figure, 1 is a bobbin, 2 is a sewing machine body, 4 is an operating lever, 5 is a micro switch, and a is a thread.

Claims (1)

[Claims] 1. A thread stand is installed in a position isolated from the sewing machine body, a ceiling board is fixed above the thread stand, and an upright piece is provided on the ceiling board, and the thread fed out from the bobbin of the thread stand is placed on the top of this upright piece. An upper thread hook is provided below the upper thread hook, and an operating lever with a thread hole at the tip for passing the thread passed through the upper thread hook is pivoted to the upright piece so as to be freely rotatable in the vertical direction. A micro switch connected to the drive device of the sewing machine main body is provided in the rotational direction of the operating lever, and a thread hook is arranged directly above the operating lever to pass the thread through the thread thread hole of the operating lever and supply it to the sewing machine main body. Stitch skipping and thread breakage in sewing machines characterized by the fact that when the operating lever is rotated due to thread tension exceeding a predetermined level, the operating lever comes into contact with the micro switch, and the operation of the sewing machine drive device is stopped. Prevention device.