JPH04102500A - Structure of throat plate in multi-thread chain stitch sewing machine - Google Patents

Abstract

PURPOSE:To eliminate the generation of a skip stitch even at high speed sewing with a simple structure and allow the sewing with a low tension multi-thread chain looper thread by forming a multi-thread chain looper thread locking structure on one side of the inter side needle groove of a throat plate. CONSTITUTION:When a multi-thread chain looper 11 is retreated to an initial position, the base part of a thread delivered from the lower surface of a needle groove 2 after scooping up a multi-thread chain looper back triangular thread (a') is released from a multi-thread chain looper thread locking recessed groove 22 to extinguish the multi-thread chain looper back triangular thread (a'), and one stitch is formed. The multi-thread chain looper back triangular thread (a') formed under a throat plate 1 is temporarily engaged with the multi-thread chain looper thread-locking recessed channel 22 of the throat plate 1, and the needle fall effective area of an inter needle 10 is forcedly extended to solve a skip stitch, so that the tension of a multi-thread chain looper thread (a) can be sufficiently lowered. Thus, no puckering is caused even in the case of a thin cloth, and the most preferable seam in which the multi-thread chain looper thread (a) is curved in a balloon can be formed.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an improvement of a double chain stitch sewing machine that forms double chain looper stitches, and in particular to a double chain stitch sewing machine that improves stitch skipping of the triangular thread on the back of a double chain looper. This relates to the structure of a throat plate in a chain stitch sewing machine.

[Conventional technology]

In a double chainstitch sewing machine, double chain loopers are placed under the interneedle so as to intersect with each other, and thread stitches are formed by intertwining the double chain needle thread and the double chain looper thread.Due to its mechanism, the feed pitch is When the number of threads is made smaller, "skipping of the r stitches of the triangular thread on the back of the double ring looper" becomes more likely to occur. That is, in a double chainstitch interlock sewing machine, as shown in FIG.
0 and the tip of the double ring looper 52 and the double ring looper back triangular part 53 formed by the double ring looper yarn a. The triangular thread a' is being scooped up. However, in general, the lowering timing of the inter needle 54 is determined by the double ring looper 5 indicated by the white arrow.
2, the displacement of the needle groove 50 and the tip of the double ring looper 52 becomes small.

In addition, when the back triangular thread a' of the double loop looper becomes loose and bends inward (see the arrow), the back triangular thread a of the double loop looper becomes loose.
Since the effective needle drop area of the inter-needle 54 constituted by ' is small, there are cases where the double loop looper does not scoop up the back triangular yarn a', which causes r stitch skipping.

For this reason, conventionally, this type of sewing machine has a structure in which a double loop clamping mechanism is added, the double loop looper thread is clamped, and the triangular thread on the back of the looper is stretched wide to prevent stitches from skipping even when sewing backwards. are also used. However, the method of clamping the double loop looper thread with a separate mechanism not only complicates the core mechanism and makes it difficult to increase the speed.

This increases the number of parts and increases costs, and it cannot be used with interlock sewing machines such as two-needle or five-thread sewing machines.

Therefore, in general, in order to tension the double-loop looper thread when the double-loop looper is retracted, the positioning of the looper is made highly accurate, and the thread tension of the double-loop looper thread is increased to suppress the deflection of the thread. In order to prevent skipped stitches, we make adjustments such as delaying the timing of the bobbin thread cam.

[Problem to be solved by the invention]

However, if the thread tension of the double loop looper thread a is increased or the bobbin thread cam is delayed, the skipped stitches can be reduced. (See Figure 8(b)) Puckering (
There is a need for a sewing machine that can sew double-loop looper threads with low tension because the sewing machine has the problem of easily causing tangles and lowering the quality of the sewing product.

The present invention has been made in view of the above problems, and provides a double chainstitch sewing machine that has a simple configuration, does not cause skipped stitches even during high-speed sewing, and is capable of sewing with a low tension double looper thread. The purpose is to provide the structure of the throat plate.

[Means to solve the problem]

The structure of the throat plate in the double chainstitch sewing machine according to the present invention is as follows:
A throat plate for a double chain stitch sewing machine in which double chain loopers are arranged under the needle of the sewing machine needle so as to intersect with each other, and thread stitches are formed by intertwining the double chain needle thread and the double chain looper thread. The gist is that a double ring looper thread locking structure is formed on one side of the inter-side needle groove, and the double ring looper thread locking structure is continuous with the needle groove and on the needle plate. This can be achieved by a concave groove formed on the bottom surface side, or by a structure in which the bottom surface of the needle plate around the needle groove portion is made thin and small protrusions are protruded from the thin portion at required positions.

[Effect]

The double ring needle thread is inserted through the inter needle, and the double ring needle thread is scooped up by the double ring looper and intertwined with the double ring looper thread, so that an interlock sewing machine stitch is formed on the interlock side. . The double-loop looper thread is inserted through the double-loop looper, and it revolves around the inter-needle according to the locus of movement of the double-loop looper. The double-loop looper thread is temporarily locked in the double-loop looper thread locking structure, which operates to forcibly tension the double-loop looper back triangular thread.

Therefore, the inter-needle reliably captures the double-loop looper yarn, thereby preventing skipped stitches.

Due to the locking action of the double loop looper back thread, even when the thread tension of the double loop looper thread is weak, it is forcibly locked to the double loop looper thread locking structure, and the inter needle drop part is forcibly expanded. Therefore, sewing with low tension double ring looper thread is possible.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a throat plate for a double chainstitch sewing machine according to the present invention will be described below with reference to FIGS. 1 to 8.

Fig. 1 is a front view (a) and a back view (b) of the needle plate 1, and Fig. 2 is a front perspective view (a) and a back perspective view (b) showing the needle groove 2.
), FIGS. 3 to 5 are cross-sectional views of the needle groove. A flat needle plate 1 provided under the needle of the sewing machine has feed insertion holes 3, 4 made of rectangular through holes and screw insertion holes 5, 5 for mounting the machine base around a needle groove 2 bored in the center. , a notch 6 etc. is formed according to the structure of the model, and a detent tooth row 7 is formed on the surface side.

The needle groove 2 has a long hole shape extending in the feeding direction with a tapered surface 21 on the back side so that the front side is longer than the back side. A double ring looper thread locking groove 22 extending in an approximately 45° direction is formed at the back end, and a thread escape tapered surface 23 is formed along the opposite edge to widen the hole width of the needle groove 2 on the back side. It forms.

As shown in FIGS. 6(a) and 6(b), an interneedle 1 is inserted into the throat plate 1 having the above structure from above through the needle groove 2, and moves back and forth.
0 and the double ring looper 11 which swings on the lower surface of the throat plate 1 are located so as to intersect with each other. It intertwines with the double ring looper yarn a originating from the double ring looper 11, and an interlock sewing stitch C is formed on the interlock side (arrow A).

At this time, the double-loop looper yarn a inserted through the double-loop looper 11 goes around the interneedle 10 in the direction of the white arrow according to the locus of movement of the double-loop looper, as shown in FIG. The base of the loop looper yarn a led out from the lower surface of the needle groove 2 is attached to the double loop looper provided on the inter-side of the needle groove 2 directly in front of the throat plate 1 in the process (Pl) of the double loop looper 11 protruding. Thread lock groove 2
2, and when the double loop looper 11 retreats to the (P2) position, the double loop looper back triangular thread a' is forcibly stretched (arrow B). Therefore, the effective needle drop area of the inter-needle 10 is expanded by the outward bending of the double-loop looper back triangular thread a' at the arrow B portion, and the inter-needle securely captures the double-loop looper thread. When the loop looper 11 retreats to the initial position (Pl), after scooping up the triangular thread a' on the back of the double loop looper, the base of the thread led out from the lower surface of the needle groove 2 comes off the double loop looper thread retaining groove 22. The back triangular thread a' of the double ring looper disappears and forms a -needle.

In the above configuration, the double loop looper back triangular thread a' formed under the throat plate 1 is temporarily engaged with the double loop looper thread locking groove 22 of the throat plate 1, and the inter needle 1o is forcibly engaged. Since the effective area of the needle drop is expanded to eliminate stitch skipping, it is possible to sufficiently lower the thread tension of the double ring looper thread a.
No puckering occurs even with thin fabrics, as shown in Figure 8 (a).
As shown in the figure, the triple ring looper thread a can form the most preferable seam curved in a balloon shape.

Next, FIG. 9 is a perspective view of the needle groove on the bottom side of the throat plate showing another embodiment of the present invention, and the double loop looper thread locking structure is replaced by the double loop looper thread locking concave groove of the above embodiment. 22 is replaced with a small protrusion 25. The needle groove 2 is similar to the first embodiment,
It has a substantially elongated hole extending in the feeding direction, and a tapered surface 21 is formed on the back side so that the front side is longer than the back side, and the hole width of the needle groove 2 is adjusted along the edge on the opposite side to the back side. A thread escape tapered surface 23 is formed which widens on the back surface side. A concave stepped portion 24 is continuously formed at the edge of the needle groove 2 on the back surface inter side (arrow A), and the small protrusion 25
is located on the back side of the edge and is erected in the recessed step 24, and by adjusting the height from the recessed step 24, the timing of locking and release of the double loop looper thread a can be changed. In addition, similar to the double-loop looper thread locking groove 22 described in the first embodiment, the double-loop looper back triangular thread a'' can be temporarily engaged and forcibly stretched. It has the effect of increasing

〔Effect of the invention〕

As described above, the structure of the throat plate in the double chain stitch sewing machine according to the present invention is such that the double loop looper back triangular thread of the double loop looper thread is temporarily locked on the back side of the throat plate, and the inter needle By configuring a double loop looper thread locking structure that expands the effective needle drop area, it is possible to sew at desired speeds from low to high speeds, and to sew with a low tension double loop looper thread. It can improve the quality of sewing products.

In addition, since the double ring looper thread locking structure can be obtained by simple processing of the back side of the throat plate, the structure is extremely simple and can be easily implemented on sewing machines currently in use, making the present invention highly economical. The effects after implementation are extremely large.

[Brief explanation of the drawing]

FIG. 1 is a front view (a) and a back view (b) showing a first embodiment of a throat plate in a double chainstitch sewing machine according to the present invention;
The figures are a front side perspective view (a) and a back side perspective view (b) showing the needle groove of the needle plate, and Figures 3 to 5 are from ■ to ■ in Figure 2.
Figure 6 is a bottom view (a) and vertical cross-sectional view (b) showing the relationship between the throat plate, inter needle, and double ring looper, and Figure 7 is an enlarged cross-sectional view of line IV-IV line and ■-V line. 8 is an explanatory diagram of the catching action of the back triangular thread of the double loop looper by the double loop looper thread locking structure, and FIG. , FIG. 9 is a perspective view of the back side of the needle groove showing another embodiment of the double loop looper thread locking structure, and FIG. 10 is an explanatory diagram showing the relationship between the conventional needle plate, inter needle, and double loop looper. It is. 1... Throat plate 2... Needle groove O... Inter needle 11... Double ring looper... Tapered surface 2... Double ring looper thread locking groove 3... Thread escape tapered surface 24 ...Concave stepped portion 5...Small protrusion a...Double ring looper thread...Double ring looper back triangular thread b...Double ring needle thread

Claims (3)

[Claims] (1) In a needle plate for a double chain stitch sewing machine, in which double chain loopers are arranged under the needle of the sewing machine needle so as to intersect with each other, and thread stitches are formed by intertwining the double chain needle thread and the double chain looper thread, A structure of a throat plate in a double chainstitch sewing machine, characterized in that a double loop looper thread locking structure is formed on one side of an inter-side needle groove of the throat plate. (2) The structure of the throat plate in the double chain stitch sewing machine according to claim 1, wherein the double chain looper thread locking structure is a concave groove continuous with the needle groove and formed on the bottom side of the throat plate. (3) The double chain stitch sewing machine according to claim 1, wherein the double ring looper thread locking structure has a structure in which the bottom surface of the needle plate around the needle groove portion is thinned and small protrusions are provided at predetermined positions in the thin portion. The structure of the throat plate in.