JPH06134169A - Method for sewing hollow loop by overlock sewing machine and device therefor - Google Patents

Abstract

PURPOSE:To smoothly pull an hollow loop into a stitch and to sew it without concentrating or curling a thread at the sewing starting top part of a cloth and further without skipping the stitch. CONSTITUTION:Before sewing is started, a cloth 52 is set so that the head part can be abutted on a guide part 6b of an upper scalpel 6b at a cutting device 6 in the state of positioning a hollow loop 50 formed at a needle plate pawl 5 in front of a needle drop part 4 and next, the cloth 52 is fed to the needle drop part 4 by temporarily increasing the feeding amount with differential feeding teeth 10 while cutting and arranging the side edge parts of the cloth 52 together with the start of a sewing machine. Afterwards, sewing is performed by returning to the normal feeding amount. Thus, the hollow loop 50 is pulled into the stitch and sewn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses an empty ring which is formed by overlock stitching of a cloth by an overlock sewing machine and which is cut off at the end of sewing and remains on a needle plate claw on the sewing machine side. The present invention relates to an empty chain stitching method and device using an overlock sewing machine that sewes into the seams during overlock stitching.

[0002]

2. Description of the Related Art An empty ring formed on a needle plate claw of an overloose sewing machine is held at the front side of a needle drop portion with an appropriate strength at the time of starting sewing of the next cloth, and at the time of overedging of the next cloth. For example, Japanese Unexamined Patent Publication No. 1-171597 discloses an empty ring stitching device that prevents the thread from being unraveled at the beginning of stitching by pulling it into the stitch.

Further, as disclosed in US Pat. No. 3,123,033 and US Pat. No. 4,072,116, an empty ring formed on a needle plate claw is started to be sewn to the next cloth. At the same time as pulling it out from the needle plate claw, holding the empty ring on the front side of the needle drop portion, retracting the sewing thread from the sewing area and starting the sewing machine, the needle is sewn until the tip of the cloth reaches the sewing area. A method is also known in which skipping is caused without forming an empty ring on the plate nail.

[0004]

However, in the case of the former method of the above-mentioned conventional empty ring sewing methods, it is necessary to strictly set the timing and the holding force for releasing the held empty ring. Since the empty ring for several stitches is formed on the needle plate claw at the start of sewing, if the held empty ring is released quickly, the empty ring 50 is difficult to be smoothly drawn into the stitch 51, and as a result, As shown in FIG.
0a is attached. In addition, such a thread block 50
In order to surely pull a into the seam 51, if the held empty ring 50 is strongly held or the release thereof is delayed, the tip of the cloth 52 is pulled toward the front side as the sewing progresses. Therefore, as shown in FIG.
There was a problem that the tip portion of the cloth 52 curls.

In the case of the latter method of the above-mentioned conventional empty-loop stitching methods, the problem as described above does not occur, but since the stitch skips even at the tip of the cloth, the part is frayed at that portion. There was a concern that it may cause a loose seam.

The present invention has been made in view of the above-mentioned circumstances, and does not cause a thread lump or curl at the tip of the fabric and does not cause skipping.
An object of the present invention is to provide a method and device for sewing an empty ring by an overlock sewing machine, which enables the empty ring to be smoothly drawn into a seam and sewn in.

[0007]

In order to achieve the above-mentioned object, in the method for sewing the empty ring by the overlock sewing machine according to claim 1 of the present invention, the main feed dog is arranged on the rear side of the needle drop portion. In addition, a differential feed dog is arranged on the front side of the needle drop section, and an upper knife and a lower knife that can move up and down are arranged on the front side of the needle drop section. Using an overlock sewing machine that is equipped with a cutting device that cuts the side edge of the needle, the empty ring formed on the needle plate claw is sewn into the seam during overedging of the next cloth. In the chain stitching method, before the start of sewing, the empty ring connected to the needle plate claw is positioned on the front side of the needle drop portion, and the tip of the cloth is moved to the lower side of the upper knife in the above cutting device. Set on the throat plate so that it abuts the protruding guide part of Then, the sewing machine is started, the side edges of the cloth are cut and aligned in cooperation with the lower knife as the upper knife moves downward, and immediately after that, the feed amount of the differential feed dog is increased to change the cloth. The tip of the differential feed dog is fed so as to advance to the needle drop portion, and then the feed amount of the differential feed dog is returned to the normal feed amount and normal sewing is performed to pull the empty ring into the seam. It is characterized by sewing.

Further, according to a second aspect of the present invention, in an empty chain stitching device using an overlock sewing machine, a main feed dog arranged on a rear side of a needle drop portion of a needle plate and a front side of the needle drop portion. It consists of a differential feed dog that is arranged and an upper knife and a fixed lower knife that are arranged on the front side of the needle drop section and move up and down in synchronization with the needle movement of the sewing machine. A cutting device that cuts the side edge of the fabric by means of a cutting device, and an empty ring positioning device that positions the empty ring connected to the needle plate claw provided rearward from the needle drop part on the front side of the needle drop part. The lock sewing machine includes a feed amount changing mechanism for changing the feed amount of the differential feed dog by an external operation, and a control mechanism for controlling the drive of the feed amount changing mechanism in relation to the progress of sewing. For the first needle, change the feed amount of the differential feed dog Kikushi, after the leading end of the fabric has passed at least the needle portion is obtained by configured to return to a normal amount of feed amount of the differential feed dog.

Further, the driving of the feed amount changing mechanism may be controlled based on a detection signal of a rotation detector provided on the sewing machine main shaft.

[0010]

According to the first aspect of the present invention, a new empty ring is hardly formed on the needle plate claws at the start of sewing the next cloth, and the seam is immediately formed on the cloth. , Without producing a large lump at the beginning of the seam,
The empty ring is smoothly sewn into the seam. As a result, even if the empty ring is released a little earlier, it will not clump. Also, since the empty ring formed on the needle plate claw before the start of sewing is normally positioned on the front side of the needle drop portion,
No skipping occurs at the tip of the fabric. Furthermore, although the feed amount by the differential feed dog is increased, it is temporary, and since the main feed dog does not act on the fabric at that time, it adversely affects the length of the seam and stretches the fabric. There is nothing to give.

According to the second and third aspects of the present invention, the cloth is set on the needle plate so that the tip of the cloth contacts the downward projecting guide portion of the upper knife of the cutting device, and the sewing machine is started. Then, the side edges of the fabric are cut and aligned by the vertical movement of the upper knife once or twice together with the needle movement, and at the same time, the tip of the fabric is fed to the needle drop portion by the differential feed dog, and the needle plate claw is almost new. The empty loop is not formed, and the fabric is immediately overburred and the empty loop extending from the needle plate claw to the empty loop positioning device under the fabric can be sewn into the overlock seam.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a main part showing a sewing machine for an empty ring using an overlock sewing machine. In FIG.
Is a needle plate and is fixed to a position corresponding to the sewing machine needle 3 on the cross plate 2 of the overlock sewing machine. The needle plate 1 is formed with a needle drop portion 4 penetrating in the vertical direction, and a needle plate claw 5 extending rearward from a portion adjacent to the needle drop portion 4 as a starting point is integrally formed. There is.

On the front side of the needle drop portion 4 and on the front side of the needle plate claw 5, there are a fixed lower knife 6A and a movable upper knife 6B movable in the vertical direction. A cutting device 6 for cutting the side edge portion of the cloth immediately before sewing is provided by relative sliding contact between the two knives 6A and 6B accompanying the downward movement. The movable upper knife 6B of the cutting device 6 has a narrow guide portion 6b protruding downward. Reference numeral 7 is a presser for holding the cloth between the needle plate 1 and the presser arm 7A pivotally supported by the sewing machine main body M on the rear side of the needle drop portion 4.
Is attached to the tip of the.

The needle plate 1 is provided with 3 pieces along the cloth feeding direction.
Rows of long holes 8 are formed, and three rows of main feed dogs 9 are arranged on the rear side of the needle drop portions 4 in these long holes 8 and 3 on the front side of the needle drop portions 4. Row of differential feed dogs 10
Are arranged. By moving these feed dogs 9 and 10 in the up-down and front-rear directions along the long hole 8, a fabric feed mechanism for feeding the fabric pressed by the presser 7 onto the needle plate 1 backward is constructed. ing. It should be noted that one of the main feed dogs 9A is arranged behind the needle plate claw 5 and performs the pulling action of the empty ring. Further, a part 1A of the needle plate 1 in front of the cutting device 6 is configured to be separable, and the separation part 1A can sandwich and position an empty ring.

Reference numeral 11 is a cloth edge detecting sensor, which detects the tip position of the cloth set on the needle plate 1 and transmits the detection signal to the sewing machine controller to start the sewing machine. Although not shown in the figure, the sewing machine spindle (see FIG. 2) 12
A rotation detector is provided for detecting the rotation amount such as the rotation angle or the rotation speed.

FIG. 2 is a perspective view showing a main part of the cloth feed mechanism described above. A main feed base 13 having the main feed dog 9 attached to the tip and a differential feed dog having the differential feed tooth 10 attached to the tip. The feed table 14 is configured to swing up and down by the eccentric movement of the first square piece 15 which is loosely fitted to an eccentric cam (not shown) attached to the sewing machine main shaft 12. Further, the bifurcated portions 13 are respectively provided at the rear end portions of the feeding bases 13 and 14.
a, 14a are formed, and these forked parts 13a, 1 are formed.
The rear end portions of the feed bases 13 and 14 are supported by a second square piece 16 slidably fitted between the four 4a. The second square piece 16 is rotatably fitted to a stepped eccentric pin 17 supported by the sewing machine frame.

An eccentric rod 18 is attached to the sewing machine main shaft 12, the eccentric rod 18 is connected to a first crank 20 fixed to a feed shaft 19, and the feed shaft 19 is swung by the swing of the eccentric rod 18. 2 cranks 21, pins 22
Also, the main feed table 13 is swung back and forth via a link (not shown). On the other hand, a differential feed rod 23 is integrally formed on the first crank 20, and a slider 24 slidably fitted to the differential feed rod 23 supports a third square piece 25. There is. A vertical groove 2 in the vertical direction is provided at a position near the rear end of the differential feed base 14.
6 is formed, and the third square piece 25 is fitted in the vertical groove 26, and the differential feed base 14 is rocked back and forth by the rocking of the feed shaft 19. With the above configuration, both feed bases 13 and 14 and each feed dog 9,
10 is configured to perform four movements (elliptical movements).

The slider 24 has a link 2
7, the rod 32 of the air cylinder 31 is connected via the intermediate lever 28, the operation lever shaft 29, and the operation lever 30. The rod 32 of the air cylinder 31 is contracted to move the slider 24 toward the tip of the differential feed rod 23. A feed amount changing mechanism capable of increasing the feed amount of the differential feed dog 10 is configured by moving the feed amount. A guide plate 34 having an arc-shaped elongated hole 33 is provided on a side portion of the operation lever 30, and a stepped screw 35 attached to an intermediate portion of the operation lever 30 is fitted into the elongated hole 33. By moving the knob 35a of the stepped screw 35 up and down, the operation lever 30 can be manually operated to change the feed amount. Also, in FIG.
Reference numeral 6 denotes a torsion spring, which biases the operation lever shaft 29 in the counterclockwise direction and has an adjusting screw 38 provided with a stopper 37.
Thus, the operation range of the feed amount changing mechanism of the differential feed dog 10 can be set.

Next, a description will be given of the operation of the essential parts of the empty chain stitching device by the overlock sewing machine having the above-mentioned structure, that is, the empty chain stitching method. When the sewing machine needle 3 and the upper knife 6B are lifted as shown in FIG. 1, the empty ring 50 connected to the needle plate claw 5 is moved by the separating portion 1A of the needle plate 1 as shown in FIG.
As shown in A, it is held on the front side of the needle drop portion 4.

Next, as shown in FIG. 3B, the cloth 52 is set on the needle plate 1 so that the tip 52a of the cloth 52 contacts the guide portion 6b of the upper knife 6B of the cutting device 6, and the presser 7 is lowered. The cloth 52 is pressed against the needle plate 1 from above. Here, since the cloth edge detection sensor 11 performs a detection operation and the detection signal is transmitted to the sewing machine control unit, if a sewing machine pedal (not shown) is depressed at this point,
The sewing machine starts, and as shown in FIG. 3C, the sewing machine needle 3 and the upper knife 6B descend to start the first empty ring formation, and the right edge 52b of the cloth 52 causes the upper knife 6 of the cutting device 6 to move.
It is cut and aligned by the relative sliding contact between B and the lower knife 6A.

Then, the rotation detector detects that the sewing machine has rotated half a turn and the sewing machine needle 3 and the upper knife 6B have started to rise, and based on the detection signal, the air cylinder in the feed amount changing mechanism (see FIG. 2). The rod 32 of 31 is driven to lower the operation lever 30 in the direction of arrow X in FIG. As a result, the differential feed dog 10 in the cloth feed mechanism is
The stroke in the front-back direction is increased, the feed amount is increased, and the fabric 52 is largely fed toward the needle drop portion 4 by the subsequent half rotation of the sewing machine. For example, when the effective cutting width by the cutting device 6 is 6 mm and the large stroke of the differential feed dog 10 is set to 6 mm correspondingly, the normal stitch length (10 to 1 per 25.4 mm) is set.
The feed will be about 3 times that of the 2nd stitch).

Subsequently, the sewing machine needle 3 and the upper knife 6B start descending again, but when the feeding action of the differential feed dog 10 in the first large stroke is finished, the cloth 52 is removed from the cloth 52 shown in FIG.
As shown in D, since the tip portion 52a has reached the needle drop portion 4, the sewing machine 3 starts predetermined sewing. When such sewing starts, the rod 32 of the air cylinder 31 in the feed amount changing mechanism is driven based on the detection signal from the rotation detector to operate the operating lever 30.
Is lifted in the direction opposite to the arrow X direction in FIG. 2 and returns to the standard position set by the stopper 37, whereby the stroke of the differential feed dog 10 in the cloth feed mechanism in the front-back direction is the normal stroke. After that, normal overedging is performed thereafter.

After the predetermined number of stitches have been sewn, when the positioning and holding of the empty ring by the separating portion 1A is released, the empty ring 52 is smoothly sewn into the seam 51. As shown in FIG. 4, the overedging fabric 52 having a well-formed sewing start end without a large thread block or curl can be obtained. Before the start of sewing, if the engagement position of the empty ring engaged on the needle plate claw 5 is set near the needle drop portion 4, the holding of the empty ring can be released immediately after the formation of the stitch on the fabric, Even if it is just positioned on the near side and not held, no yarn lump is generated.

The mechanism for changing the feed amount by the differential feed dog 10 is not limited to the structure described in the above embodiment, but may be any structure.

As a means for controlling the feed amount by the differential feed dog 10, a sensor for detecting the position of the tip end portion 52a of the cloth 52 is provided near the needle drop portion 4, and the feed amount is usually determined by the sensor signal. Even if the feed amount is returned to the normal feed amount as in the above embodiment, the rotation detector detects the number of rotations (including the number of hand movements), and further, the timer is used to return to the normal feed amount. You may Further, if the feed amount is always increased at the beginning of sewing, it becomes possible to adapt it only by the means for returning to the normal feed amount.

[0026]

As described above, according to the first aspect of the present invention, at the start of sewing of the cloth, the new empty ring is hardly formed on the needle plate claw, and the seam is immediately formed on the cloth. Therefore, a large lump-shaped thread is not generated, and the empty ring can be smoothly drawn into the seam and sewn in. Also, since sewing can be started while the empty ring is normally held on the front side of the needle drop portion, stitch skipping occurs at the tip of the fabric, and as a result, defective products such as fraying and loose seam formation occur. Occurrence can be prevented. Further, the feed amount by the differential feed dog is only temporarily increased, and the feed amount is returned to the normal feed amount before reaching the feed area by the main feed tooth, which adversely affects the stitch length and causes wrinkles. Therefore, good overedging can be performed without giving stretch to the fabric.

According to the second and third aspects of the present invention, the cloth is set on the needle plate such that the tip of the cloth contacts the downward protruding guide portion of the upper knife of the cutting device, and the sewing machine is started. When the sewing starts, the tip of the fabric is rapidly fed to the needle drop point, so that almost no new empty ring is formed on the needle plate claw, and the edge stitches are immediately formed on the fabric, and the fabric is also immediately formed. An empty ring extending from the needle plate claw to the empty ring positioning device underneath is reliably and smoothly sewn into its overlock seam. Therefore, even if the timing of releasing the empty ring is slightly earlier, the thread lump is not generated, and the overedging can be performed so as to naturally follow the cloth tip having the good shape sewing start end.

[Brief description of drawings]

FIG. 1 is a perspective view of essential parts showing an empty ring sewing device using an overlock sewing machine which is an embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing a cloth feeding mechanism and a feed amount changing mechanism.

3 (A) to (D) are plan views of essential parts for explaining the operation at the start of sewing.

FIG. 4 is a plan view of an essential part of the fabric on which overedging with empty chain stitching is completed.

FIG. 5 is a plan view of a main part for explaining a defect caused by a conventional method of sewing with an empty chain.

FIG. 6 is a plan view of a main part for explaining another drawback of the conventional empty ring sewing method.

[Explanation of symbols]

 1 Needle plate 3 Sewing needle 4 Needle drop portion 5 Needle plate claw 6 Cutting device 6A Lower knife 6B Upper knife 6b Guide section 9,9A Main feed dog 10 Differential feed dog 11 Cloth edge detection sensor 50 Air ring 51 Stitch 52 Cloth

Claims (3)

[Claims] 1. A main feed dog is arranged on the rear side of the needle drop portion, a differential feed dog is arranged on the front side of the needle drop portion, and a vertical feed is arranged on the front side of the needle drop portion. Using an overlock sewing machine that is composed of a movable upper knife and a lower knife, and is equipped with a cutting device that cuts the side edge of the fabric by relative sliding contact of both knife, the empty ring formed on the needle plate claw is used. This is a method of stitching an empty ring using an overlock sewing machine that is sewn into the seam at the time of overedging of the next fabric, and the empty ring that is connected to the needle plate claw before the start of sewing is positioned on the front side of the needle drop portion. In this state, set the cloth on the needle plate so that the tip of the cloth comes into contact with the downward protruding guide portion of the upper knife in the above cutting device, and then start the sewing machine to move the upper knife downward. Together with the lower knife, the side edges of the fabric are cut and aligned, and immediately after that The feed amount of the differential feed dog is increased to feed the cloth so that the tip of the fabric advances to the needle drop point, and then the feed amount of the differential feed dog is returned to the normal feed amount to perform normal sewing. By performing the above, the empty ring is pulled into the seam and sewn in, and the empty ring sewing method by the overlock sewing machine is characterized. 2. A main feed dog arranged on the rear side of the needle drop portion of the needle plate, a differential feed dog arranged on the front side of the needle drop portion, and a side portion on the front side of the needle drop portion. The upper and lower fixed knives are arranged on the sewing machine and move up and down in synchronism with the needle movement of the sewing machine. In an overlock sewing machine equipped with an idler ring positioning device that positions the idler ring connected to the needle plate claw facing toward the needle drop portion on the front side, a feed for changing the feed amount of the differential feed dog by an external operation The feed amount changing mechanism and a control mechanism for controlling the drive of the feed amount changing mechanism in relation to the progress of sewing are provided, and the feed amount of the differential feed dog is increased at the first needle at the beginning of sewing to The differential feed is performed at least after the tip has passed the needle drop point. An empty-loop sewing-in device using an overlock sewing machine, which is configured to return the feed amount of teeth to a normal amount. 3. A rotation detector for detecting the rotation amount of the sewing machine spindle is provided, and the drive of the feed amount changing mechanism is controlled based on a detection signal from the rotation detector. An empty ring sewing device using a lock sewing machine.