JPH0510795Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Field of Use This invention relates to a bobbin thread claw that is used in a sewing machine that forms double chain stitches, and that engages with the bobbin thread during stitch formation to create an allowance in the seam.

Prior Art A sewing machine that forms a double chain stitch, for example, a safety stitch sewing machine as shown in Fig. 5, is used to perform safety stitches using edge stitches C and double chain stitches S on thin fabrics W such as cutter shirts and blouses. When a stretchable thread such as synthetic spun thread is used as the bobbin thread (looper thread) T for double chainstitching, the bobbin thread T contracts after stitching and appears on the back side of the fabric, creating a double chainstitch. S becomes a straight line like two threads drawn together,
Moreover, the shrinkage of the bobbin thread T often causes puckering in the fabric, hardens the seams, and reduces the feel of the fabric. In order to prevent this, even if the tension of the bobbin thread is loosened by adjusting the thread tension device during sewing, it will be pulled back when the looper retreats, and the amount of bobbin thread paid out in the finished sewing state will not be increased sufficiently, and the thread tension will be lowered. Skip stitches are more likely to occur due to yarn slack.

Problems to be solved by the invention This invention can be easily applied to sewing machines that form double chain stitches, and can be used to create so-called so-called so-called stitches as shown in Figure 4, which have a soft texture without puckering even on thin fabrics. The purpose of this invention is to make it possible to form a double chain stitch BS in which the bobbin thread T is swollen, which is called a balloon stitch.

Means for Solving the Problems and Effects Therefore, the present invention provides a bobbin thread engaging pawl with the tip facing forward in the cloth feeding direction on the side where the loop advances near the needle path between the throat plate and the looper in a double chainstitch sewing machine. The looper, which makes an elliptical motion in a direction perpendicular to the fabric feeding direction, moves forward and captures the upper thread looper, and then moves the looper to avoid the needle by moving the lower thread connected to the seam through the looper's eye hole. The looper is inserted between the throat plate and the pawl, and then the looper is moved back to engage the pawl, and the needle rises to come out of the bobbin thread loop extending from the seam of the fabric and engage with the loop. After this is released, the engagement of the bobbin thread with the claw is released by feeding the fabric.

Here, the pawl may be attached directly to the back surface of the throat plate or attached to the main body of the sewing machine along the needle hole, but in either case, it is preferable that the attachment position be adjustable.

The double chainstitch sewing machine equipped with a bobbin thread claw according to the present invention is most suitable for sewing thin fabrics by using elastic thread for the bobbin thread, thereby creating a double chainstitch with a soft texture without clumping. However, it can also be used when using non-stretchable threads or when sewing thick fabrics; this gives each seam a rounded appearance, creating a soft texture known as a balloon stitch. You can obtain a double chain seam with a unique texture.

Embodiment Figure 1 shows the back side of the throat plate used in a safety stitch sewing machine. In the figure, 1 is the throat plate, 2 is the needle groove through which the edge stitch needle (not shown) passes, and 3 1 is a throat plate claw for forming edge stitches, 4 is a through hole for a feed dog, 5 is a needle hole through which the double chain stitch needle 9 (see Figures 3A to E) passes, and 6 is a screw 7 This is a claw for engaging the bobbin thread that is fixed to the back surface of the throat plate.The claw tip 6a is located beside the needle hole 5, facing forward in the cloth feeding direction, and is located slightly below the bottom surface of the throat plate (see Figure 2). Lupa 11
It is located above. Code 1 shown in Figure 2
0 is the line of action of the needle 9, which is inclined with respect to the throat plate, similar to the edge stitching needle described above.

Next, the formation of a double chain stitch using the above claw will be explained with reference to FIGS. 3A to 3E.

When the needle 9 passing through the bobbin thread loop 13a connected to the looper 11 rises from the bottom dead center (at this point, the bobbin thread loop 13a is hooked on the claw 6), the looper 11 moves from the left dead center to the right (see Fig. 3A). ), capturing the needle thread loop 12 (Figure 3B). Needle thread loop 12
The looper 11, which has captured the bobbin thread, moves further to the right while pulling the bobbin thread (as the looper moves to the right, a thread reeling mechanism (not shown) loosens the thread), and reaches the right dead center (Fig. 3C). During this time, the needle 9 is connected to the bobbin thread loop 13a,
It passes through the needle hole 5 of the needle plate and the cloth and rises, and the cloth is fed by the feed dog, and the cloth advances by one stitch. This causes the bobbin thread loop 13a to be caught on the claw 6.
is pulled and comes out from the claw 6. Tsutsute Roopa 11
performs a needle avoidance movement toward the front in the cloth feeding direction before and after reaching the right dead center, but at this time, the lower thread 13 connected to the seam enters between the throat plate 1 and the claw 6 from the looper 11. When the looper 11 performs a needle avoidance movement toward the front and moves to the left, a triangle is formed by the looper 11, the bobbin thread 13 that connects to the stitch from the eye hole of the looper, and the needle thread loop 12 caught by the looper. When the needle 9 descends into the needle (Fig. 3D), the looper 11 moves further to the left (as the looper moves to the left, the bobbin thread is pulled in by the thread take-up mechanism,
(The stitches are tightened in cooperation with the left row of the looper.) The bobbin thread that has entered between the throat plate and the claw is caught by the claw and bent, and in this state the looper pulls the needle thread loop that is caught on the looper. 12 (Fig. 3E).
Then it reaches left dead center.

According to this embodiment, after the needle descends into the triangle formed by the looper, the needle thread loop captured by the looper, and the bobbin thread that connects to the seam through the eye hole of the looper, until it comes out of the fabric. , the pawl holds the bobbin thread loop, thereby ensuring an extra amount of bobbin thread that is caught on the pawl. As a result, it became possible to form a double chain seam BS with a plump and soft texture as shown in Figure 4.
Even if an elastic thread is used as the bobbin thread, it will not shrink and cause puckering or the seams will not become too tight.

Effects of the invention As described above, the bobbin thread claw of the present invention engages with the bobbin thread during seam formation to secure a bobbin thread in excess of the amount of thread required for seam formation, creating a margin for the seam. This creates a double chain seam with a fluffy and soft texture.When forming a double chain seam on thin fabrics, even if you use elastic thread for the bobbin thread, it may shrink and cause puckering. , the seams will not become too tight.

[Brief explanation of the drawing]

Figure 1 is a back view of the throat plate with the bobbin thread claw attached, Figure 2
The figure is a sectional view of the main part of the throat plate, Figures 3A to 3E are explanatory diagrams showing the process of forming a double chain stitch, and Figures 4 and 5 are safety stitches formed on the edges of the fabric. The figure shows an example of using a bobbin thread claw when forming a double chain stitch.
FIG. 5 is a diagram showing a conventional example. 1... Throat plate, 5... Needle hole, 6... Nail, 9...
Needle, 11... Roopa.

Claims (1)

[Scope of claim for utility model registration] (1) A needle that carries needle thread and moves up and down through the throat plate, and an elliptical needle that carries bobbin thread and extends below the throat plate in a direction perpendicular to the cloth feeding direction. In a double chainstitch sewing machine equipped with a looper that makes an elliptical motion and forms a double chainstitch in cooperation with the needle, place the tip of the toe on the side where the looper advances near the needle path under the throat plate on the fabric feeding side. A double chainstitch sewing machine, characterized in that a bobbin thread claw is provided facing the needle, so that the bobbin thread engages with the bobbin thread claw when the looper makes a needle avoidance movement and retreats. (2) The double chainstitch sewing machine according to claim 1, wherein the bobbin thread claw is attached to the throat plate. (3) The double chainstitch sewing machine according to claim 1, wherein the position of the bobbin thread claw is adjustable.