JPS6141496A - Apparatus for forming linking stitch by two threads - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to industrial sewing machines, and more particularly to a device for forming two-thread overlock stitches in the form of Federal Standard Catalog No. 503. .

The invention solves the problem of how to increase the reliability of the operation, in particular of the interaction between the various members forming the stitch.

This problem is solved by a device with a lower hook, the tip of which forms a flat part on the side that makes light contact with the needle and a wedge-shaped bulge on the side opposite to the side facing the previously formed stitch. form a section and lightly touch the upper hook. The upper hook also has a forked end, and the lower arm of the fork is curved towards the lower hook and has a shape adapted at least partially to the bulge of the lower hook. Furthermore, the upper hook has a rounded protrusion on the side opposite to the side facing the lower hook.

The present invention provides an apparatus for forming double thread overlock stitches, particularly Federal Standard Catalog No. 5'03 overlock stitches, on an industrial sewing machine.

[Prior Art and Problems Therewith] As is well known, industrial sewing machines are capable of forming a large variety of stitches, all of which are numbered and standardized. Among these stitches, No. 503 is known to be formed on the edge of fabric using an industrial sewing machine, and this industrial sewing machine has a needle equipped with a thread and a needle equipped with a thread. A lower hook and an upper hook without thread are provided.

This type of stitch is therefore formed with a device that has three main parts: a needle, an upper hook, and a lower hook, and that operates with two threads.

The lower hook with the thread always swings below the surface on which the fabric rests, while the upper hook, known as the hook, has a forked end and carries the thread of the lower hook onto the fabric. lead to the top. This upper hook moves in the opposite direction to the lower hook, moving from below the plane of the fabric to above.

Next, the movement of forming the stitches will be explained in detail.

Initially, the needle is at bottom dead center, the two hooks are in a fully open position, ie, each hook is at its furthest distance from the other hook and needle, and the needle is located midway between the two hooks. From this position, the needle rises in one direction toward top dead center, forming a loop with the thread of the needle passing through the fabric. For example, the tip of the lower hook moving to the right passes the page through this loop, while the upper hook moves in the direction of the lower hook while rising (from the left)
.

The needle continues to rise and pass through the top of the fabric, and while rising, the needle passes past the lower hook and guides the thread of the lower hook onto the fabric. When this state is reached, the feed dog of the sewing machine starts feeding the fabric.

After reaching the top dead center, the needle again begins its downward stroke, and during this downward movement it passes through the loop formed by the thread of the lower hook and led to the uppermost position by the upper hook. Thus, the needle engages the thread of the lower hook and holds the thread of the brace, and both the upper and lower hooks return to their initial positions and tighten the stitch.

The above operation is well known and conventionally used in industrial sewing machines. The basic requirements for these industrial sewing machines are operating speed and reliability, ie, the ability to operate without dropping stitches. These contradictory matters have only been partially satisfied by conventional sewing machines. For example, it is known that the upper hook tends to damage the thread of the lower hook.

In fact, the engagement area is very narrow and is in contact with the working path of the upper hook. Therefore, even if the arrangement of the thread on the lower hook is slightly shifted, the upper hook will not engage the thread and will only pass near the thread to be hooked.

Furthermore, it is known that when forming an overlock stitch with two threads, the area where the descending needle lightly contacts the upper hook in the uppermost position is an area where the stitches are likely to be dropped. The needle is inserted between the thread of the 10th hook on the side facing the previously formed stitch, and the thread of the 11th hook on this first hook. Again, the area 11 passes through is so narrow that even if the operator pulls on the fabric slightly to make it taut, the nail will not penetrate the required area. During this movement, the needle contacts the upper hook and heats the nail and the hook, risking damage to the needle and the hook and burning the thread. Therefore, the technical problem of the present invention is to eliminate the first drawback and to increase not only the reliability and operational accuracy of the sewing machine, but also the operating speed of the sewing machine.

Furthermore, it is an object of the present invention to particularly sufficiently and reliably control the arrangement of the sections forming the stitches, to provide an extremely simple structure, and to improve the conventional members forming the stitches.

Furthermore, the invention aims at obtaining a device in which the various components can also be used with a minimum of adjustments and modifications.

[Means, actions and effects for solving the problem] The above technical problems and objects are achieved by a device that forms an overlock stitch using two threads in a sewing machine, and this device engages the thread at the tip. It has an upper hook equipped with a fork and a lower hook equipped with thread, and both the upper and lower hooks are used to attach the thread. , the lower hook swings laterally with respect to the needle under the fabric so that it is inserted between the button rising from the bottom dead center and the thread of this needle, and the upper hook is inserted between the thread of the lower hook and the button rising from the bottom dead center. The lower hook swings in a phase opposite to that of the lower hook along an operating path that engages the thread and guides the thread near the needle at the uppermost turn, and the tip of the lower hook is formed to be almost flat on the side that lightly contacts the needle. A roughly wedge-shaped protrusion is formed on the side that lightly contacts the tenth hook and faces the previously formed stitch, and this protrusion allows the thread of the lower hook to pass through and to operate the tip. The upper hook is curved in the direction of the lower hook and has a curved part partially adapted to the shape of the protrusion, The curved portion laterally engages the thread pulled out from the guide surface.

Other characteristics and advantages of the invention will become apparent from the following description of exemplary embodiments, which refers to the accompanying drawings.

[Example] In the drawings, the entire forming apparatus for forming an overlock stitch using two threads according to the present invention is designated by the reference numeral 1 in FIG.

This device uses two-thread overlock stitches (Federal Standard Catalog N
o, 503). Briefly, the device 1 comprises a needle 2 driven by a lever 3, a lower hook 4 driven by a swinging lever 5, and a hook 6 driven by a mechanism consisting of a connecting rod 7 and a crank 8. ing.

As is clear from FIGS. 2 and 2a, the lower hook 4 traces an arc, which arc is always located below the horizontally spread fabric. On the other hand, the upper hook moves along a working path that intersects with the lower hook from the bottom side of the fabric to the top side. The needle 2 moves along a linear working path inclined with respect to the vertical direction, as shown in FIG. Within the working path of the needle, both sides of the needle lightly contact the lower and upper hooks.

As shown in FIGS. 9 to 11, the needle 2 is provided with thread 2a as a first thread, and the lower hook 4 is provided with thread 2a as a second thread.
A is provided. The threads 2a and 4a cover the edges of the fabric 9.

According to the present invention, the tip of the lower hook 4 is formed to be substantially flat on the side that lightly contacts the needle 2 (see FIG. 2), and on the other hand, faces the previously formed stitch and lightly contacts the upper hook 6. On the side (see FIG. 10), a unique protrusion 10, clearly shown in FIGS. 3 and 4, is provided.

The protrusion 10 is sharp and has a wedge-like shape. A hole is provided at the rear of the protrusion 10, and the second thread 4a is inserted through this hole. Furthermore, the protrusion 10 is formed with a guide surface 11, which is advantageously arranged obliquely with respect to the operating direction of the tip of the lower hook. This guide surface determines the position of the thread 4a on the side facing the stitch formed at the end of the lower hook.

As shown in FIGS. 3 to 8, the upper hook 6 is attached to the shank 1.
2, and attach the fork 1 to the front end of this shank as a hooking part.
3 is formed. This fork 13 has a curved portion 14 that is curved in the direction of the lower hook 4. This curved portion 14 is the lower arm of the flange 13. In practice, this curve or lower arm 14 is shaped to be adapted to move along the back surface of the projection 10, so that the lower hook is of a relatively thin construction, as is conventional.

Furthermore, as shown in FIG. 3.4.5, the upper hook is provided with a rounded protrusion 15 on the side opposite to the side facing the lower hook 4. This projection is located immediately behind the fork 13, and the thickness of the upper hook decreases rapidly in the direction of the shank 12.

Finally, FIGS. 1 and 2 show the connection of the upper hook 6 to a connecting rod 7 supporting it in a manner unique to the invention. In practice, a block 16 is provided, which is integral with the connecting rod 7 and is provided with precisely located holes 17. This hook 16 and the precisely located hole 17 allow the upper hook 6 to be placed precisely by simply inserting part of the shank 12 into this hole 17.

As shown in FIG. 1, the shank 12 can also be provided laterally with a stem 8 substantially parallel to the connecting rod 7, which can be inserted into the bore 17. In this case, the height of the upper hook 6 can be accurately positioned, but the horizontal position must be adjusted by appropriately rotating the stem 18 around its axis.

FIG. 2 shows the block 16 with precisely positioned holes 17, which are arranged transversely to the connecting rod 7. FIG. In this case, the upper hook can be reliably placed in the correct position simply by inserting the shank 12 until it is flush with one end of the hole 17, and then the angle of the axis of the upper hook in the circumferential direction can be adjusted. Just that is enough.

9-11 illustrate the operation of the device according to the invention. This device is essentially not significantly different from the conventional device described above with respect to the operation and movement of the needle 2, lower hook 4, and upper hook 6. However, thread 2a,
There is a big difference in the position of thread 4a, and this thread 2a
, 4a take a new travel path that is both theoretically and practically satisfactory.

In fact, the guide surface 11 of the protrusion 10 draws out enough thread from the lower hook 4 so that it can be easily carried by the upper hook 6 (Fig. 3.4.10) There is no danger of each hook colliding. Since the upper hook 6 engages the yarn 4a pulled out from the guide surface 11 not in the tangential direction but in the transverse direction, the reliability with respect to engagement of the curved portion 14 of the fork 13 is increased.

Since the protruding portion 10 at the tip of the lower hook 4 also has a unique long shape, the lower hook can be easily inserted between ε12 and the thread 2a (Fig. 9), and the thread 2a will gradually slide out. is pulled out from needle 2. The projection 15 of the upper hook 6 also ensures that the thread 4a of the lower hook 4 is pulled out when the needle 2 is inserted between the thread of this needle and the upper hook 6 (Figs. 5 and 11). When the second thread 4a is pulled out, the needle 2 can be safely moved to the correct position, while a small gap is formed between the needle 2 and the upper hook 6. This gap prevents accidental contact between the elbow 2 and the upper hook 6, which could cause heating and damage. Therefore, the present invention is able to achieve the above object and further, by the unique above technique of the present invention, the play is enlarged and protruded rather than improved and adjusted, making it much more accurate than the conventional one. can be operated and the speed of forming stitches can be increased.

Various modifications and changes can be made to the present invention within the scope of this technical idea. It is also possible to replace it with other technically equivalent members.

In implementation, it is also possible to change the dimensions and strength of the members used as necessary.

[Brief explanation of the drawing]

FIG. 1 shows an overall perspective view of the device according to the invention, and FIG.
The figure shows a part of the apparatus of FIG. 1 along with the working paths of each member;
Figure 2a schematically shows the operating path in Figure 2 viewed from the front, and Figures 3 and 4 are enlarged plan and bottom views of the ends of the upper and lower hooks that are closest to each other. 5th
The Figures show the passage of the needle tip when the upper hook is in the uppermost position, Figures 6.7.8 show an elevation, plan and side view, respectively, of the upper hook according to the invention, and Figures 9-9. FIG. 11 is a diagram illustrating the operation of the apparatus according to the invention for forming respective stitches. DESCRIPTION OF SYMBOLS 1... Forming device, 2... Upper hook, 3, 5... Lever, 4... Lower hook, 6... Upper hook, 7...
Connecting rod, 8... Crank, 9... Cloth, 10...
Projection, 11... Guide surface, 12... Shank, 13
... fork, 14 ... curved part, 15 ... protrusion,
2a, 4a... Thread.

Claims (6)

[Claims] (1) An upper hook having a fork for hanging a thread at one end, a lower hook provided with a thread, and a needle provided with a thread, the lower hook being swung horizontally with respect to the needle on the underside of the fabric. The upper hook is inserted between the needle and the needle thread that is moving upward from the bottom dead center, and the upper hook hooks the thread of the lower hook and transports it to the vicinity of the needle at the top dead center. A device that swings in the opposite phase to the upper hook, lower hook, and needle to form a two-thread overlock stitch on the edge of the fabric by a sewing machine, in which the tip of the lower hook is formed to be substantially flat on the side that lightly contacts the needle, and has an approximately wedge-shaped protrusion on the side facing the previously formed stitch that lightly contacts the upper hook, and this lower hook The thread passes through the protruding part, the protruding part has a guide surface inclined with respect to the moving direction of the tip part to draw out the thread of the lower hook, and the upper hook has a guide surface that is curved in the direction of the lower hook. Overstitching with two threads, characterized in that the curved part is curved and partially conforms to the shape of the protruding part, and this curved part laterally engages the thread pulled out from the guide surface. A device that forms (2) The device according to claim 1, wherein the upper hook has a rounded protrusion on the side opposite to the side facing the lower hook, and this protrusion is located immediately behind the fork of the upper hook. A device that pulls out the thread from the lower hook. (3) The apparatus of claim 1, wherein the curved and bent curved portion of the upper hook is the lower arm of the fork. (4) The device according to claim 1, wherein the upper hook is connected to a connecting rod supporting the upper hook through a block, the block being precisely arranged so that the shank of the upper hook can pass through it. A device with a hole in it. (5) A device as claimed in claim 4, in which the precisely disposed hole is provided substantially parallel to the connecting rod, and the upper hook extends through a stem projecting laterally from the shank. A device for engaging said precisely located holes. (6) A device according to claim 4, wherein the precisely disposed hole is disposed substantially transversely to the connecting rod, and the shank is arranged such that the stem portion can be fully inserted into the connecting rod. A device that is engageable.