JPH0343919B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a method for cutting the top thread of a multi-needle sewing machine using the top thread.

PRIOR ART Several devices are already known that are capable of automatically cutting off the top thread that connects to the right end needle stitch at the end of sewing after the sewing operation is completed. Utsukai Showa 58-
No. 177086 and JP-A No. 59-55286 show that the top thread is cut at the end of sewing, when the needle and upper feed dog are at the top dead center, and when the spretsher is stopped at the left swing dead center. , Cut the decorative thread between the stitch of the right end needle at the end of sewing and the hook part of the spreader with a reciprocating hook-shaped scalpel from the diagonally rear left side of the left needle in the latter case, and from the diagonally right front side in the former case. It is now possible to capture and do so.

Problems to be Solved by the Invention In all of the conventional devices described above, the distance between the presser foot and the spreader, which stops at the left swing dead center, is relatively small, partly because the feed dog is located at the top dead center on the throat plate. If it is narrow and in the latter case, the needle becomes an obstacle and the knife's entry angle (angle with the throat plate) becomes smaller.
Therefore, the cutting device comes close to the throat plate and becomes a hindrance to fabric manipulation during sewing. In the former case, the tip of the presser foot becomes a hindrance to the downward movement, and the entry angle of the knife is limited to an extremely narrow range, making it difficult to grasp the top thread. Furthermore, when the hook-shaped knife captures and pulls the top thread, the top thread hanging on the needle thread at the end of sewing is pulled, causing the decorative width to shrink, resulting in the phenomenon of sewing shrinkage.

The present invention has been made with the aim of solving the above-mentioned problems.The approach angle of the knife is increased to make it easier to grasp the top thread, and the cutting device does not interfere with sewing work. This is to prevent shrinkage.

Means for Solving the Problems In other words, the present invention temporarily stops the needle and feed dog near the bottom dead center and the spreader near the right swing dead center at the end of sewing, so that the right end needle extends from the seam at the end of sewing and presses down. After the hook of the top thread cutting device reciprocates to catch, cut and grasp the decorative thread between the gold and the decorative thread guide, the sewing machine is then rotated half a turn to raise the needle and rotate the spretzer to the left. The sewing thread is cut below the throat plate to finish sewing.

The cutting device may be placed on the front side of the needle, but is preferably placed near the rear of the right needle and as far as possible above the needle plate or bed.

This is because if the device is located behind the needle and away from the bed, it will be less likely to interfere with the work.

Note that the hook may be made into a female shape so that it can be cut when catching and pulling the top thread, or it may be cut in cooperation with a fixed knife placed on the retreating path. Preferably, at the same time as cutting is performed in cooperation with a fixed scalpel, the upper decorative thread on the supply side is gripped and held at the rear of the needle. This ensures that the top thread is sewn into each needle stitch from the first stitch at the beginning of sewing.

Embodiment The sewing machine shown in FIG. 2 is a three-needle interlock sewing machine equipped with a known needle fixed position stop device and a device that automatically cuts the needle thread and looper thread under the throat plate at the needle top dead center. A sewing machine equipped with a decorative thread cutting device A, in which the decorative thread cutting device A is placed diagonally behind the right needle N1 and above the bed ₁ , and the hook 2 is directed downward to the left from diagonally behind the right needle. The most favorable example of advancing and retreating is shown.

The top thread cutting device A will be explained based on FIG. 1. A mounting base 5 is fixed to a bracket 4 fixed to a sewing machine arm 3, and a rotary solenoid 6 is fixed to the mounting base 5. The mounting base 5 is provided with a long groove formed toward the needle, and a fixing bar 8 and a hook bar 9 are fixed in the groove so that the former can be adjusted in position in the longitudinal direction, and the latter hook bar 8 can be slid. They are mated. A hook 2 is attached to the tip of the hook bar, and a knife 11 and a presser plate spring 12 are attached to the tip of the fixed bar on both sides of the hook 2.
It is attached so that it pinches the holding plate spring 1.
2 comes into elastic contact with the hook 2, so that the hook 2 is pressed against the knife 11. Lever 13 fixed to the shaft of rotary solenoid 6
A drive lever 14 extending in the longitudinal direction is fixed to the drive lever 14, and a pin 1 is inserted through a long hole 15 at the tip of the drive lever.
6 is attached to the hook bar 9. As a result, when the drive lever 14 pivots clockwise in the figure, the hook bar 9 is pulled up diagonally to the right, and when the drive lever 14 pivots counterclockwise, it is pushed diagonally downward to the left. As the hook 9 advances and retreats, the hook 2 extends over the presser foot 18 from the right end needle stitch at the end of sewing and advances and retreats over the decorative thread extending to the decorative thread guide 19 supported by the arm 3. The hook 2 is always urged upward by a tension spring 20 stretched between the lever 13 and the mounting base 5, and is kept in the raised position by the hook bar 9 hitting a stopper (not shown). be.

Cutting of the top thread at the end of sewing is carried out as follows.

When the sewing is finished and the worker steps back on the treadle (not shown), a signal is sent to the needle fixed position stop device, and the needles N ₁ , N ₂ , N ₃ reach the bottom dead center and the spreader 22 reaches near the dead center of the right swing and stops. At this time, the top thread passes through the top thread handler 23 attached to the needle stock 22 and passes through the long hole 2 of the top thread guide 19.
4, it comes off from the hook part 26 of the spreader and extends straight to the right needle seam at the end of sewing on the upper surface of the workpiece W which has been completely sewn. In this state, with the operation of the rotary solenoid 6, the hook 2 enters beyond the top decorative thread D between the long hole 24 of the decorative thread guide 19 and the right needle seam at the end of sewing on the upper surface of the workpiece, and when retreating, Capture the decorative thread D (Figure 3A). The hook 2 that has captured the top thread pulls the thread, cuts it in cooperation with the knife 11, and holds the free end of the top thread on the supply source side between it and the presser plate spring 12 (Fig. 3B). . The top thread D is cut as described above, and the needle, which stops at the bottom dead center during this period, begins to rise after cutting, and at the same time, the spreader 22 also begins to rotate leftward from the rightward dead center. During the rotation, the hook portion 26 of the spreader hooks the upper decorative thread D between the cutting device holding the free end and the long hole 24 of the decorative thread guide 19, and pulls it to the left (see Fig. 3C). ), it reaches the left swing dead center and stops (3rd
Figure D). At this time, the needles N ₁ , N ₂ , and N ₃ have reached the top dead center. Thereafter, each of the needle threads S ₁ , S ₂ , S ₃ and the looper thread (not shown) are cut by a known thread cutting device under the throat plate, and then the needle thread wiper 27 enters and captures each of the needle threads. (Fig. 4A), and hold it diagonally upward to the right (Fig. 4B). Upper thread wiper 27 as above
If you do not use the free end of each needle thread, hold it under the presser foot etc. to ensure that the top thread is sewn into each needle stitch from the first stitch when the next sewing starts. is desirable.

In this state, the next sewing is started. Figures 5A to 5C show the order in which the cover thread is sewn in for the first stitch.
N ₁ , N ₂ , and N ₃ begin to fall from the top dead center, and at the same time the spreader 22 also begins to rotate to the right from the left swing dead center (FIG. 5A). Next, the needle enters between the front and back cover threads which are folded back from the hook part of the spreader, and further descends. As a result, the needle threads S ₁ , S ₂ , and S ₃ that extend downward through the eye of the needle are attached to the top thread D, which loosens as the spreader rotates to the right, compared to when forming a normal flat stitch. They are engaged in the same manner (FIG. 5B), and are pushed down to lie on the workpiece W. FIG. 5C shows a state in which the needle has reached the bottom dead center, the spreader has reached the right swing dead center, and the top thread D has been sewn into each needle stitch from the first stitch.

Effects of the Invention As described above, in the present invention, the needle and feed dog are near the bottom dead center, the spreader is temporarily stopped near the right swing dead center, the hook of the top thread cutting device moves back and forth, and the right end needle is moved back and forth at the end of sewing. This device is designed to catch the top stitching thread between the stitch and the decorative thread guide.The feed dog is located below the throat plate, and the decorative thread guide is located above the spret. As in the past, the distance between the guides is wider than the distance between the right end needle seam, which is raised by the feed dog protruding above the throat plate, and the spretzer, which has reached the left swing dead center, and the approach angle of the hook is relatively This makes it easier to grasp the top thread, the cutting device can be installed away from the bed or throat plate in a position where it will not interfere with work, and the hook can catch the top thread. When pulling, the left needle that stops near the bottom dead center engages the top stitching thread on the seam side, which prevents shrinkage of the stitching width and prevents sewing shrinkage. Since the thread is held down and cut near the right needle, there are no mistakes in cutting, and the length of the thread that connects to the fabric is a constant length.
Moreover, it has the advantage of being short.

[Brief explanation of drawings]

Fig. 1 is a perspective view of the main part of Fig. 2, Fig. 2 is a front view of a sewing machine equipped with a top thread cutting device, and Fig. 3A to D
The figure is a perspective view showing the order of operation before and after cutting the top thread, Figures 4A and B are perspective views showing the state in which the needle thread wiper captures and sweeps away the needle thread, and Figures 5A to C are perspective views of the top thread wiper. FIG. 6 is a perspective view showing the order in which the top stitching thread is sewn in when forming stitches, FIG. 6 is a diagram showing changes in the inclination angle of the top stitching thread according to the present invention, and FIG. 7 is a diagram showing a conventional example. 1...Bed, 2...Hook, 3...Sewing machine arm,
5... Mounting base, 6... Rotary solenoid, 8... Fixed bar, 9... Hook bar, 11... Female, 12... Holding plate spring, 13... Lever, 14... Drive lever, 18
...Presser foot, 19. Decorative thread guide, 22. Spreader, 23. Top decorative thread handler, 27. Upper thread remover.

Claims (1)

[Scope of Claims] 1. A sewing thread cutting device that cuts the needle thread and looper thread below the needle thread, and a cover thread cutting device provided near the rear of the right needle, which has a hook that can move forward and backward for capturing the cover thread. At the end of sewing, in a multi-needle sewing machine equipped with a sewing machine, the feed dog and needle are stopped near the bottom dead center, the spreader is stopped near the right swing dead center, and then the decorative thread is inserted from the right rear of the hook decorative thread guide. It moves forward and backward under the guide, extends from the right end needle stitch at the end of sewing, captures and pulls the decorative thread between the presser foot and the decorative thread guide located above the spretzer, cuts it at the cutting position, and removes the cut end. The sewing machine is then operated to move the feed dog and needle to near the top dead center and the spreader to near the left swing dead center, and then the needle thread and looper thread are cut by the sewing thread cutting device. 2. A plurality of needles attached to the lower end of the needle bar in parallel in a direction intersecting the cloth feed direction of the sewing machine, and a decorative thread guide provided on the right side of the needles and provided with a long hole for guiding the top decorative thread; It has a spreader that moves back and forth in front of the needle through between the sewing machine bed and the decorative thread guide to shake the top decorative thread left and right, and also includes a sewing thread cutting device that cuts the needle thread and the looper thread below the throat plate. A multi-needle sewing machine includes: a hook that advances and retreats in a straight line from the right rear of the decorative thread guide toward the bottom of the decorative thread guide; a fixed knife and a presser spring that clamp the hook from both sides in the retracted position of the hook; and the sewing thread cutting device described above. Separately, there is a drive device installed at the rear right of the decorative thread guide to drive the hook.At the end of sewing, the feed dog and needle are stopped near the bottom dead center, the spreader is stopped near the right swing dead center, and then the hook is removed. The needle thread of the right needle advances and retreats and descends, holding down the top thread on the fabric and extending toward the long hole side.The cover thread is caught and pulled below the decorative thread guide, and the top thread is cut and held at the cutting position. A needle fixed position stop device that operates the sewing machine, moves the feed dog and needle to near the top dead center, moves the spreader to near the left swing dead center, and then controls the sewing thread cutting device to cut the needle thread and purl thread. Thread cutting device for multi-needle sewing machines.