JPH0767516B2 - Structure of needle plate in double chain stitch sewing machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improved double chain stitch sewing machine for forming a double ring looper stitch, and more particularly to a double ring looper with a double triangle looper back triangle thread having improved stitch skipping. The present invention relates to the structure of a needle plate in a chain stitch sewing machine.

[Conventional technology]

In the double chain stitch sewing machine in which the double ring looper is arranged under the needle of the inter needle so as to intersect with each other, and the thread is formed by the entanglement of the double ring needle thread and the double ring looper thread, the feed pitch is When the thread is made smaller, the double-loop looper back triangle thread "eye jump" is more likely to occur. That is, in the double chain stitch interlock sewing machine, as shown in FIG. 10, the double ring looper back triangular portion 53 formed by the needle groove 50 of the needle plate, the sword tip of the double ring looper 52 and the double ring looper thread a. The inter-needle 54 having the double ring needle thread b inserted therein is lowered to scoop the double ring looper back triangular thread a '. However, in general, the descending timing of the inter-needle 54 is the position (arrow P) which is turned to the retracted side in the movement trajectory of the double ring looper 52 shown by the white arrow, and therefore the needle groove 50
And the double ring looper 52 When the amount of displacement of the sword tip becomes small and the double ring looper back triangular thread a'is loosened to cause inward bending (see arrow), the double ring looper back triangular thread a ' In some cases, the effective needle drop area of the configured inter-needle 54 becomes small and the double ring looper back triangular thread a'is not picked up.
It is a cause of "eye jump".

For this reason, in this type of sewing machine, a double ring thread clamp mechanism has been added in addition to the conventional structure, and the double ring looper thread is clamped so that the looper back triangular thread is greatly stretched to prevent the eye from skipping even in the case of backward sewing. The thing of is also used. However, the method of clamping the double-loop looper thread by another mechanism not only complicates the mechanism of the part and makes it difficult to increase the speed, but also increases the number of parts and increases the cost. It cannot be used in interlock sewing machines such as threads.

Therefore, in general, when the double ring looper is retracted, the double ring looper thread is stretched so that the looper is aligned with high accuracy, and the thread tension of the double ring looper thread is increased to suppress the bending of the thread. In addition, adjustments such as delaying the timing of the bobbin thread cam are made to prevent skipping.

[Problems to be Solved by the Invention]

However, if the thread tension of the double-loop looper thread is increased or the bobbin thread cam is delayed, the double-loop looper thread a is tensioned in the sewing direction ( (See FIG. 8 (b)) Since there is a problem that puckering (pulling) is likely to occur and the quality of the sewn product is deteriorated in a thin material, a sewing machine that can sew a double ring looper thread with low tension has been demanded. It was

The present invention has been made in view of the above problems, and is a double chain stitch sewing machine that has a simple structure, does not cause skipping even at high speed sewing, and can be sewn with a low tension double ring looper thread. It is intended to provide a structure of a needle plate.

[Means for Solving the Problems]

The structure of the needle plate in the double chain stitch sewing machine according to the present invention is
A needle plate for a double chain stitch sewing machine, wherein the double ring looper is arranged under the needle of the sewing machine so that the double ring looper is crossed with each other to form a thread line by the entanglement of the double ring needle thread and the double ring looper thread. The gist of the present invention is to form a double-loop looper locking structure on the right bottom surface of the needle groove portion of the double-loop looper in the cloth feeding direction during the movement process of the double-loop looper to temporarily engage the double-loop looper back triangular thread. The double loop looper thread locking structure is continuous with the needle groove portion,
Further, it can be achieved by a structure in which a concave groove formed on the bottom surface side of the needle plate or the bottom surface of the needle plate peripheral needle plate is thinned and a small projection is provided at a required position of the thinned portion.

[Action]

The double ring needle thread is inserted into the inter needle, the double ring needle thread is scooped by the double ring looper and entangled with the double ring looper thread, and the interlock sewing machine seam is formed on the inter side. . The double ring looper thread is inserted into the double ring looper, and it wraps around the inter-needle due to the locus of movement of the double ring looper.At this time, the needle groove of the needle plate is on the right bottom surface in the cloth feeding direction. The double ring looper thread locking structure provided is temporarily locked with the double ring looper thread and operates so as to forcibly stretch the double ring looper back triangular thread.

Therefore, the inter needle reliably catches the double-loop looper thread and prevents the stitch skipping.

Even if the thread tension of the double-loop looper thread is weak due to the locking action of the double-loop looper back thread, the double-loop looper thread locking structure is forcibly locked and the inter-needle drop portion is forcibly expanded. Therefore, it is possible to sew with a low tension double loop looper thread.

〔Example〕

A first embodiment of the needle plate in the double chain stitch sewing machine according to the present invention will be described below with reference to FIGS. 1 to 8.

1 is a front view (a) and a back view (b) of the needle plate 1, FIG. 2 is a front side perspective view (a) and a back side perspective view (b) showing the needle groove 2, and FIGS. FIG. 5 is a sectional view of the needle groove. In the flat needle plate 1 provided below the needle of the sewing machine, there are feed insertion holes 3 and 4 formed of rectangular through holes around the needle groove 2 formed in the central portion, and screw insertion holes 5 and 5 for mounting the machine base. The notch 6 and the like corresponding to the structure of the model are formed, and the detent tooth row 7 is formed on the front 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 surface side is longer than the back surface side, and the back surface inter side of the needle groove 2 (the needle groove portion of the needle plate Right bottom surface in the cloth feeding direction: arrow A) A double ring looper thread locking groove 22 extending approximately 45 ° is formed at the end on the far side of the edge, and the hole width of the needle groove 2 is set along the opposite edge. A yarn relief taper surface (23) that widens on the back side is formed.

As shown in FIGS. 6 (a) and 6 (b), the inter needle 10 which is inserted into and retracted from the upper side of the needle groove 2 with respect to the needle plate 1 having the above structure.
And the double ring looper 11 which oscillates on the lower surface of the needle plate 1 cross each other, and the double ring needle thread b inserted through the inter needle 10 is scooped by the double ring looper 11 and Heavy Ring Looper 11
The interlock sewing machine seam c is formed on the inter side (arrow A) by being entangled with the double loop looper thread a inserted in the.

At this time, the double ring looper thread a inserted into the double ring looper 11
Is rotated around the inter-needle 10 in the direction of the white arrow by the locus of movement of the double ring looper as shown in FIG. 7, and the base of the thread derived from the lower surface of the needle groove 2 of the double ring looper thread a is During the process in which the heavy ring looper 11 protrudes (P1), the double ring looper 11 is temporarily engaged with the double ring looper thread locking groove 22 provided on the back side of the needle plate 1 on the inter side of the needle groove 2, Operates to forcibly stretch the double-loop looper back triangular thread a '(arrow B) when is retracted to the (P2) position. Therefore, the needle drop effective area of the inter-needle 10 is expanded by the outward bending of the double-loop looper back triangular thread a'indicated by the arrow B, and the inter-needle surely catches the double-loop looper thread, and When the ring looper 11 retracts to the initial position (P1), the double ring looper back triangular thread a '
After scooping, the base of the thread led out from the lower surface of the needle groove 2 is disengaged from the double ring looper thread locking concave groove 22 and the double ring looper back triangular thread a ′ disappears to form one needle.

In the above structure, the double loop looper back triangular thread a'formed under the needle plate 1 is temporarily engaged with the double loop looper thread locking groove 22 of the needle plate 1 to forcibly interlock the interneedle 10 Since the effective area of the needle drop is expanded to eliminate skipping, it is possible to sufficiently reduce the thread tension of the double ring looper thread a, and puckering does not occur even on thin cloth, As shown in Fig. (A), the double loop looper yarn a can form the most preferable stitch in which the double loop looper yarn a is curved in a balloon shape.

Next, FIG. 9 is a perspective view of the needle groove portion on the bottom side of the needle plate showing another embodiment of the present invention. The double ring looper thread locking structure has the double ring looper thread locking groove of the above embodiment. 22 is replaced with a small protrusion 25. Similar to the first embodiment, the needle groove 2 is a substantially elongated hole extending in the feed direction, and has a tapered surface 21 formed on the back side so that the front surface side is longer than the back surface side and the back surface inter side. A thread escape taper surface 23 is formed along the opposite edge to widen the hole width of the needle groove 2 on the back surface side. A concave step portion 24 is continuously formed at the edge of the back side of the needle groove 2 on the back side (arrow A), and the small projection 25 is positioned on the back side of the edge and is erected on the concave step portion 24. It has a structure with a concave step
Double ring looper thread a by adjusting the height from 24
It is possible to change the timing of locking and disengaging the double looper looper thread triangular groove a'as well as the double ring looper thread locking groove 22 described in the first embodiment. It engages with and forcibly tensions.

[Effect of the Invention] As described above, the structure of the needle plate in the double chain stitch sewing machine according to the present invention is such that the double ring looper back triangular thread of the double ring looper thread is temporarily locked to the back surface of the needle plate. By constructing the double loop looper thread locking structure that expands the effective area of needle drop of the inter-needle, it is possible to sew at a desired speed from low speed to high speed, and at the same time, a low tension double loop is used. It can be sewn with a looper thread and the quality of the sewn product can be improved. In addition, since the double ring looper thread locking structure is obtained by simple processing of the back surface of the needle plate, the structure is extremely simple and can be easily implemented even on the sewing machine currently in use. The effect after implementation is extremely large.

[Brief description of drawings]

FIG. 1 is a front view (a) and a back view (b) showing a first embodiment of a needle plate in a double chain stitch sewing machine according to the present invention, and a second view.
The figure shows a front side perspective view (a) and a back side perspective view (b) showing needle grooves of the needle plate, and FIGS. 3 to 5 are III-I in FIG.
II, IV-IV and VV line enlarged sectional views, FIG. 6 is a bottom view (a) and a longitudinal sectional view (b) showing the relationship between the needle plate, the interneedle and the double ring looper, and FIG. Is an explanatory view of the trapping action of the double loop looper back triangular thread by the double loop looper thread locking structure, and FIG. 8 is a back side seam showing the state of the double loop stitch of the present application (a) and the conventional (b). FIG. 9 is a back side perspective view of a needle groove showing another embodiment of the double ring looper thread locking structure, and FIG. 10 is an explanatory view showing the relationship between the conventional needle plate and the interneedle and the double ring looper. Is. 1 ...... Needle plate, 2 ...... Needle groove 10 ...... Inter needle, 11 ...... Double ring looper 21 ...... Tapered surface 22 ...... Double ring looper Thread locking groove 23 ...... Thread escape taper surface, 24 …… Concave step 25 …… Small protrusion, a …… Double ring looper thread a ′ …… Double ring looper back triangular thread b …… Double ring needle thread

Claims (3)

[Claims] 1. A needle plate for a double chain stitch sewing machine, wherein double ring loopers are arranged under the needle of a sewing machine so as to intersect with each other, and thread lines are formed by entanglement of the double ring needle thread and the double ring looper thread. In the needle groove portion of the needle plate in the cloth feeding direction, a double-ring looper thread locking structure for temporarily engaging the double-ring looper back triangular thread during the movement process of the double-ring looper is formed. The structure of the needle plate in the double chainstitch sewing machine, which is characterized by a needle. 2. The structure of the needle plate in the double chain stitch sewing machine according to claim 1, wherein the double ring looper thread locking structure is a groove which is continuous with the needle groove portion and is formed on the bottom side of the needle plate. 3. The double ring looper thread locking structure according to claim 1, wherein the bottom surface of the needle plate in the peripheral portion of the needle groove portion is made thin and a small projection is provided at a required position of the thin portion. The structure of the needle plate in the sewing machine.