JP2002066185A - Overlock sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a two needle overlock sewing machine which can keep an open ring formed following advancing cloth in a retained posture so as not to overlap a needle location and stably making reverse stitching to sew the open ring into following cloth at the start of sewing. SOLUTION: This overlock sewing machine is equipped with a needle thread pull off device 7 to act on needles 5, 5 and needle threads S1, S2 stretched between thread tension devices 41, 42 and to pull off the needle threads S1, S2 to thread tension devices 41, 42 and a looper thread returning device 8 to act on looper thread S4 stretched between the looper and the thread tension device 44 to pull back the looper thread S4 to the thread tension device 44. The needle thread pull off device 7 is first actuated and then the looper thread returning device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overlock sewing machine used for overcasting side edges of fabric.

[0002]

2. Description of the Related Art The up and down movement of a needle above and below a needle plate and the left and right movement of an upper looper above the needle plate and a lower looper below the needle plate cause a side edge of the cloth fed onto the needle plate to be edged. Many overlock sewing machines that perform overlock sewing have a scalpel for cutting the end of the fabric at the front of the needle drop position in order to trim the side edges of the fabric to be sewn and feed the needle to the needle drop position correctly. Therefore, at the start of sewing, the tip of the cloth is set at the front position of the scalpel, and the sewing operation is started in this state, and the needle and the looper are rotated several times until the tip reaches the needle drop position. Because the operation of, the front of the sewing start end,
An empty ring in which the needle thread and the looper thread are entangled without the interposition of the fabric is added.

[0003] This blank ring not only impairs the beauty of the sewn product but also causes fraying of the seam. The bar-tacking operation is a factor that hinders improvement in the efficiency of the sewing operation.

Therefore, conventionally, the sewing of the preceding fabric is completed by forming an appropriate length of empty ring at the end of the sewing of the preceding fabric,
The empty ring is turned to the front side of the needle drop position, that is, the cloth feeding side, and is cut and held appropriately, and in this state, reverse stitching for starting sewing of the next cloth is performed. When this reverse sewing is performed, the empty ring held as described above is automatically sewn into the regular seam together with the empty ring formed at the front of the sewing start end of the next fabric, and the above-described bartacking is performed. Work becomes unnecessary, and work efficiency can be improved.

FIGS. 9 to 13 are explanatory views of the procedure for carrying out reverse stitching using a two-needle overlock sewing machine. 1 in the figure
The needle plate 1 has a needle hole 10 opening at a substantially central portion in the front-rear direction, a female hole 11 opening at a position in front of the needle hole 10, and an opening at the front, rear, and one side of the needle hole 10. Multiple feed holes 12
And ...

The needle hole 10 has a leading edge and a trailing edge which are substantially perpendicular to the cloth feeding direction (indicated by an open arrow), a side edge connecting one side thereof along the feeding direction, and a side edge. On the other side of the edge, it has a rectangular opening shape surrounded on all sides by the inner edge of the needle plate outer claw 13 extending from the front edge to just before the rear edge, and inside the needle hole 10 Needle drop positions A, A respectively corresponding to a pair of left and right needles (not shown) are arranged along the front edge, and between the needle drop positions A, A, the needle plate outer claw 13 is provided.
A needle plate middle claw 14, which also forms a needle plate claw, protrudes from the front edge in a manner extending in the feed direction. An empty ring holder 15 that cuts and holds the empty ring is provided in front (in front of) the needle plate 1 as described later.

FIG. 9 shows a state in which the preceding fabric K has been sewn. The sewing by the overlock sewing machine is performed by two needles that move up and down at the needle drop positions A and A, and an upper looper that moves left and right above and below the needle plate 1 so as to cross these vertical positions. A lower looper (not shown) is used to form an overcast stitch B on the side edge of the fabric K fed onto the needle plate 1, and the sewing end end E of the fabric K is set at the needle drop position A, After passing through A for an appropriate length, the sewing operation of the sewing machine main body is stopped and the processing is terminated.

At the end of such sewing, an appropriate length of empty ring C is formed behind the sewing end end E of the cloth K in a manner continuous with the regular seam B along the side edge of the cloth K. . This empty ring C is entangled by the operation of the needle and the looper performed after the cloth K passes, with the needle thread and the looper thread held by the needle and looper threads supported by the needle plate outer nail 13 and the needle plate middle nail 14. Is formed.

When performing the above-described reverse stitching from such a state, first, the sewn cloth K is pulled backward,
After the empty ring C entangled with the outer nail 13 of the needle plate and the middle nail 14 of the needle plate is pulled out rearward, as shown by an arrow in FIG. 10, the needle is turned from the left side of the needle plate 1 to the front side of the needle drop positions A, A. Then, the extracted empty ring C is guided to the empty ring holder 15 disposed at the front position of the needle plate 1 while extending. The empty ring retainer 15 is integrally provided with a knife for cutting the empty ring C and means for clamping and holding the empty ring C after cutting. As shown in FIG. 10, the middle portion is cut and held in an extended state, and the cloth K is provided with an appropriate length of empty ring C at the sewing end E side.
Is separated.

After holding the empty ring C as described above, sewing of the next fabric K 'is started. FIG. 11 shows a state at the start of sewing. As shown in FIG.
The sewing start end E 'is aligned with the front side of the cutting knife 16 located inside the sewing machine, and the sewing machine body is started in this state, and the cloth K' is cut with the edges aligned by the operation of the cutting knife 16. Then, it is sent to the needle drop positions A, A and sewn.

At this time, since the cutting knife 16 is positioned in front of the needle dropping position A, at the time of the above-described sewing, the needle is moved until the sewing start end E 'reaches the needle dropping position A. As shown in FIG. 12, the needle plate outer nail 13 and the needle plate middle nail continue to the hollow ring C formed at the end of sewing of the preceding cloth K.
An empty ring C is formed in a state entangled with 14.

[0012] After the sewing start end E 'of the succeeding fabric K' reaches the needle drop position A, the thus formed empty ring C is
As shown in FIG. 13, the fabric K 'is pushed out as the sewing start end E' advances due to the feed of the fabric K ', and is pulled forward by the hollow ring holder 15, so that the fabric K' starts from the sewing start end E '.
Are sequentially sewn into the seam B formed along the side edge of
The area up to the holding end is sewn into the seam B to complete the reverse stitching.

The outer nail 13 of the needle plate and the middle nail 14 of the needle plate provided in the needle hole 10 support the hollow ring C formed as described above, while lowering the fabric K or K 'being sewn. They are supported from the side and function to prevent them from falling into the needle hole 10 with the needle descending to the needle drop positions A, A.

[0014]

Various proposals have hitherto been made for the purpose of successfully performing the reverse stitching as described above. The overlock sewing machine disclosed in Japanese Unexamined Utility Model Publication No. 7-16781 is provided with a needle thread feeding device between a needle and a thread tensioner, and this device is operated before the sewing of the fabric is started to reduce the stitch at the start of sewing. The needle thread is formed in a relaxed state, and is configured so that the empty ring C can be favorably drawn into the seam.

However, in a two-needle overlock sewing machine, as shown in FIG.
Is formed by entanglement of the needle thread and the looper thread on both the outer nail 13 and the inner nail 14 of the needle plate, and as described above, the preceding fabric K which has been sewn is pulled backward. In this state, a part of the empty ring C remains so as not to be able to escape from the needle plate outer nail 13 and the needle plate middle nail 14, and in this state, the fabric K is turned forward and the empty ring C extracted earlier is removed. Empty cage
When held at 15, the empty ring C remaining on the needle plate outer claw 13 and the needle plate middle claw 14 is pulled forward, and as shown in FIG.
Needle drop position A on the right side set between 13 and the middle plate 14
When the sewing of the subsequent fabric K 'is started in this state, the remaining empty ring C is pierced by the needle descending to the needle drop position A on the right side, and the fabric K' is stabbed. There is a problem that the sewing is sewn to the sewing start end E 'of K' and remains as a lump without being drawn into the seam B formed thereafter, resulting in deterioration of the finish.

The overlock sewing machine disclosed in Japanese Utility Model Laid-Open Publication No. Hei 7-16781 has no effect on the pulling of the hollow ring C sewn on the subsequent fabric K 'in this manner, and the above-mentioned problem is solved. Can not be solved.

According to Japanese Patent Application Laid-Open No. Hei 9-128844 by the applicant of the present invention, the base end is pivotally supported by a support shaft located on the left side of the needle drop position, and along the upper surface of the needle plate according to the rotation of the support shaft. It is provided with a rotating flat annular guide, and the annular guide is
It is operated when the preceding fabric K which has been sewn is turned forward, and the empty ring C held by the needle plate outer nail 13 and the needle plate middle nail 14 as described above is moved to the needle drop position A, the rear side of A. There is disclosed an overlock sewing machine configured to push the sewing machine rightward and forward.

According to this configuration, by the operation of the idle ring guide, the empty ring C comes out of the claw 14 of the needle plate, and after the cloth K is turned, the idle ring C is removed from the base end of the outer nail 13 of the needle plate. Cage 15
And is held without overlapping with the needle drop position A on the right side, and is not pierced by the needle descending to the needle drop position A after the subsequent sewing of the fabric K 'is started, and the above-described problem is solved. can do.

However, in this configuration, the empty ring guide is located on the upper surface of the needle plate, which hinders the feeding of the cloth sewn on the needle plate, and furthermore, the operating mechanism of the empty ring guide. Is difficult to dispose in a limited space below the needle plate. The hollow ring C formed on the rear side of the preceding fabric K is formed so that the needle thread and the looper thread are under the tension applied to each of the needle plate outer claws 13 and the needle plate middle claws 14.
Because it is formed to be entangled firmly, there is a case that the extrusion by the above-mentioned empty ring guide cannot be performed smoothly,
Conversely, there is a possibility that a part of the hollow ring C is broken by excessive extrusion, which may hinder the start of sewing of the subsequent fabric K '.

The present invention has been made in view of such circumstances, and by adjusting the tension of a needle thread and a looper thread, a holding posture which does not overlap an empty ring formed continuously with a preceding fabric at a needle drop position. It is an object of the present invention to provide an overlock sewing machine which can stably perform reverse stitching in which the empty ring is sewn at the start of sewing of the subsequent fabric.

[0021]

An overlock sewing machine according to a first aspect of the present invention is a state in which a needle thread and a looper thread are entangled with a needle plate claw provided on one side of a needle plate to form an empty ring. Below, a needle thread feeding means for acting on the needle thread stretched between the needle and the thread tensioner to feed out a suitable length of the needle thread on the side of the thread tensioner, and between the looper and the thread tensioner. And a looper thread returning means that acts on the stretched looper thread and pulls the looper thread on the looper side toward the thread tensioner side.

In the present invention, after the sewing of the preceding fabric is completed, the needle thread feeding means is operated in a state in which the needle plate nail and the intermediate support nail have an empty ring, and the needle thread on the thread tensioner side is operated. By pulling out the appropriate length to loosen the needle thread on the needle side, the entanglement of the empty ring is alleviated, the empty ring is pulled out by pulling the preceding fabric backward, and the looper thread returning means is provided. Operating, pulling the looper yarn forming an empty ring together with the needle thread back to the looper side, and urging the empty ring extracted as described above toward the looper side, that is, the needle plate claw side,
The holding posture when the preceding fabric is turned and the empty ring is cut and held by the empty ring holder in front of the needle plate is kept at an appropriate position that does not overlap the needle drop position.

An overlock sewing machine according to a second invention of the present invention is characterized in that the needle thread feeding means in the first invention includes means for increasing or decreasing the length of the needle thread feeding during operation. An overlock sewing machine according to a third aspect of the present invention is characterized in that the looper thread returning means in the first and second aspects of the present invention includes means for increasing or decreasing the return length of the looper thread during its operation.

In these inventions, the feeding length of the needle thread during the operation of the needle thread feeding means and the return length of the looper thread during the operation of the looper thread returning means can be increased or decreased. A ring is reliably pulled out and a proper holding posture is realized thereafter.

An overlock sewing machine according to a fourth aspect of the present invention is provided between the looper thread returning means and the looper according to the first to third aspects of the present invention, and an auxiliary thread tensioner for applying a clamping resistance to the looper thread. It is characterized by having a vessel.

In the present invention, the auxiliary thread tensioner disposed between the looper thread return means and the looper adds a clamping resistance to the looper thread pulled back by the looper thread return means,
The looper thread leading to the looper is maintained in a tensioned state, and the sewing of the subsequent fabric is prevented from being started with the looper thread loosened.

Further, in the overlock sewing machine according to the fifth invention of the present invention, the needle is located above the needle plate, and the needle thread and the looper thread are entangled with the needle plate claw provided on one side of the needle plate, and the idle ring is provided. After the sewing operation is stopped in a state where is formed, the needle thread feeding means is operated to feed out the needle thread on the side of the thread tensioner,
Loosening the loop of the loop with the needle plate claw through the needle thread, operating the looper thread return means to pull the looper thread back to the thread tensioner side, and removing the looper thread on the looper side; And a control means for performing a control operation including a step of pulling and urging the empty ring toward one side of the needle plate via the needle plate.

In the present invention, after the sewing operation is stopped, the control means performs a series of operations of operating the needle thread feeding means to loosen the needle thread, and then operating the looper thread return means to pull the looper thread back. During this time, the sewing maker waits for the operation of the needle thread feeding means, performs an operation of pulling the finished fabric sewn backward, reliably pulls out an empty ring formed by entanglement with the needle plate nail and the middle support nail, Subsequently, waiting for the operation of the looper thread return means, the preceding fabric is turned forward, an operation is performed in which the extracted empty ring is guided to the empty ring retainer, and the needle is dropped at the needle drop position by the biasing of the pulled back looper thread. A desirable holding posture that does not have to be realized.

[0029]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a front view schematically showing a configuration of a main part of an overlock sewing machine according to the present invention,
An overlock sewing machine is configured by fixedly supporting the sewing machine main body 4 on the sewing machine bed 3.

On one side (left side) of the sewing machine main body 4, a head section 40 is continuously provided at an appropriate distance above the sewing machine bed 3, and on a lower surface of the head section 40, a front side in FIG. A needle bar 50 is hung down, and a pair of left and right needles 5 and 5 are attached to the lower end of the needle bar 50 via a needle stopper 51. The needle bar 50 moves up and down in accordance with the sliding of the needle bar 50 in the axial length direction caused by the transmission of the needle bar.

On the upper surface of the sewing machine bed 3 opposing the lower part of the head part 40, a sewing table 30 in the form of a flat plate is provided in a substantially horizontal manner. Needle drop positions A, A (FIG. 5) set on the needle plate 1 attached to the sewing table 30 so as to be flush with the upper surface thereof as described later.
To FIG. 7).

An upper looper (not shown) and a lower looper 6 (see FIGS. 5 to 7) are provided inside the sewing machine bed 3, and the upper looper is driven by the needle from inside the sewing machine bed 3 by the transmission from the inside. From the right side of the plate 1, it moves forward and backward along the upper surface of the needle plate 1. Similarly, the lower looper 6
From the left side of the needle plate 1 to move back and forth in the left-right direction along the lower surface of the needle plate 1.

Four thread tensioners 41, 42, 43 and 44 are arranged side by side in the left and right direction on the upper front surface of the sewing machine main body 4, and a thread guide plate 45 is mounted above these. The thread tensioners 41, 42, 43, and 44 apply resistance to the needle thread or the looper thread clamped between the base and the thread tension knob through a pair of thread tension discs, and are pulled out to one side. It has a known configuration for applying tension.

The two thread tensioners 41 and 42 on the left are used for the needle threads S ₁ and S ₂ supplied to the needles 5 and 5, respectively. These needle threads S ₁ and S ₂ are connected to the thread guide plate. After being inserted into the corresponding position of 45, it is clamped between the different thread tensioners 41 and 42, pulled out to the left from them, and provided with a thread reeling device 46 and a small tension plate 47 provided on the front surface of the head portion 40. Through each different needle 5,5
Is set to The needle yarns S ₁ and S ₂ set in this way are operated in accordance with the vertical movement of the needles 5 and 5 by the operation of the thread reeling device 46 under the tension appropriately set by the operation of the thread tensioners 41 and 42. The needle plate 1
Used for sewing the fabric above.

The two thread tensioners 43 and 44 on the right side are looper threads S ₃ and S which are supplied to the upper looper and the lower looper 6, respectively.
_After the looper yarns S ₃ and S ₄ are respectively inserted into the corresponding positions of the yarn guide plate 45, the looper yarns S ₃ and S ₄ are clamped by separate yarn tensioners 43 and 44, respectively, and pulled out downward from these. Then, it is guided into the sewing machine bed 3 through thread path holes 48 and 49 formed on the upper surface of the sewing machine bed 3, and is set on the upper looper and the lower looper 6. The looper yarns S ₃ and S ₄ set in this way are separately fed out under the tension appropriately set by the operation of the thread tensioners 43 and 44 in accordance with the forward and backward movements of the upper looper and the lower looper 6, respectively. It is used for sewing the fabric on the needle plate 1 together with the needle threads S ₁ and S ₂ .

The overlock sewing machine according to the present invention is provided with a thread tensioner 41 for the needle thread S ₁ , S _{2 in} the middle of the thread path of the needle thread S ₁ , S ₂ set as described above. The needle thread feeding device 7 is provided between the thread feeding device 42 and the thread feeding device 46. The needle thread feeding device 7 is provided with a feeding cylinder 70 attached to the upper left of the juxtaposed positions of the thread tensioners 41, 42, 43, and 44 with its axial direction extending vertically, and a feeding cylinder extending downward. A delivery member 71 attached to the tip of the output rod of the cylinder 70. Reference numeral 72 in the drawing denotes a mounting base for the feeding cylinder 70.

The lower looper 6 set as described above is used.
Middle of the looper thread S ₄ of the yarn path of the use, specifically, between the thread tension regulator 44 and Itodoana 49 for looper thread S _4, the looper thread return apparatus 8 and the auxiliary thread tensioner 9 Is provided. The looper thread return device 8 includes a return cylinder 80 attached to the lower part of the juxtaposition of the thread tensioners 41, 42, 43, and 44 with the axial length direction left and right, and a return cylinder extended leftward. And a return member 81 fixed to the tip of the output rod 80. Reference numeral 82 in the figure denotes a mount for the return cylinder 80.

The auxiliary thread tension unit 9, similar to the thread tension unit 44, and pinching the looper thread S ₄ via the pair of thread tension discs between the base and the thread tension knob, the yarn path hole 49 the is obtained by a structure for adding tension to the looper thread S ₄ drawn to the side of the lower looper 6 through. Thereby, the lower looper thread S ₄
The tension set by the operation of the auxiliary thread tensioner 9 is added together with the tension set by the thread tensioner 44.

FIG. 2 shows a needle thread feeder 7 and a looper thread return device 8 which are connected to an auxiliary thread tensioner 9 and thread tensioners 41, 42, 4.
It is a perspective view shown with 3,44. As shown in the figure, the feeding member 71 of the needle thread feeding device 7 is provided with a feeding cylinder 70.
Is an L-shaped member comprising a short fixed piece fixed to the output end and a long action piece bent downward from the fixed piece and extending downward. Holes 73 are formed, and the needle threads S ₁ and S ₂ stretched between the thread tensioners 41 and 42 and the thread reeling device 46 are inserted through the elongated holes 73.

The feeding cylinder 70 of the needle thread feeding device 7 is usually in a contracted state shown by a solid line in FIG. 1, and is indicated by a two-dot chain line in FIG. 1 in response to the supply of air from an air source (not shown). It extends downward as shown. By this extension, the needle thread S inserted through the long hole 73 of the feeding member 71
₁ and S ₂ are pressed downward by the upper edge of the long hole 73 between the thread tensioners 41 and 42 and the thread reeling device 46, and 2 in FIG.
The state shown by the dashed-dotted line is reached, and the thread is pulled out from the side of the thread tensioners 41 and 42 against the added resistance due to them. The feeding member 71 is attached to the output rod of the feeding cylinder 70 so as to be able to change its position in the axial direction, and the feeding length of the needle threads S ₁ and S ₂ accompanying the extension of the feeding cylinder 70 is determined by the feeding member 71. It can be increased or decreased by changing the mounting position.

The return member 81 of the looper thread return device 8 includes a short fixed piece fixed to the output end of the feeding cylinder 80,
An L-shaped member having a long acting piece bent rightward from the fixed piece, and a thread hole 83 formed in the action piece.
Looper thread S ₄ which is stretched between the thread tension regulator 44 and the auxiliary thread tension unit 9 is inserted through.

The return cylinder 80 of the looper thread return device 8
Unlike the feeding cylinder 70 of the needle thread feeding device 7, is normally in an extended state shown by a solid line in FIG. 1, and contracts in accordance with the supply of air from an air source (not shown). Due to this shortening, the looper thread S ₄ inserted into the thread hole 83 of the return member 81 is pressed rightward between the thread tensioner 44 and the auxiliary thread tensioner 9, and is indicated by a two-dot chain line in FIG. The state shown in FIG. In this case, the additional tension by the thread tension regulator 44 and the auxiliary thread tension unit 9, by setting as the former is larger, looper thread S ₄ that is pressed as described above, the auxiliary thread tension unit 9 is pulled back to the thread tensioner 44 side. The return member 81 is attached to the output rod of the return cylinder 80 so as to be able to change its position in the axial direction in the same manner as the feeding member 71 of the needle thread feeding device 7, and the looper thread S ₄ along with the contraction of the return cylinder 80. Can be adjusted by changing the mounting position of the return member 81.

FIG. 3 is a block diagram showing a configuration of a control system of the overlock sewing machine according to the present invention. Reference numeral 2 in the figure denotes a control unit using a microprocessor. The input side of the control unit 2 is connected to an operation pedal 20 that is stepped on by a sewing manufacturer, and the control unit 2 is connected to the operation pedal 20.
, The presence or absence of a stepping or stepping back operation by the sewing manufacturer is recognized.

The input side of the control unit 2 has a needle position sensor 21 for detecting the operating position of the hands 5 and 5 which move up and down as described above.
This output is used as a feedback signal for stopping sewing in a state where the needles 5 and 5 are at the upper positions, as described later. The needle position sensor 21 can be configured as, for example, a sensor that detects the rotational position of the main shaft for driving the hands 5 and 5.

The output of the control section 2 is supplied to the feeding cylinder 70 of the needle thread feeding device 7 and the return cylinder 80 of the looper thread returning device 8, and more specifically, to supply and discharge air to these cylinders 70, 80. The feeding cylinder 70 is extended in accordance with an operation command given from the control unit 2, and the return cylinder 80 is shortened in accordance with an operation command given from the control unit 2. It is.

The output of the control unit 2 is supplied to a presser foot 22 for holding the material being sewn between the needle plate 1 and the needle plate 1. More specifically,
The presser foot is provided to a presser lifting device that raises and lowers the presser foot 22, and the presser foot 22 can be moved up and down with respect to the upper surface of the needle plate 1 in response to an elevating command from the control unit 2. Further, the output of the control unit 2 is given to a sewing machine motor M serving as a drive source of each unit of the sewing machine including the hands 5 and 5, the upper looper, and the lower looper 6, and more specifically, to a drive circuit of the sewing machine motor M. The needles 5 and 5, the upper looper, and the lower looper 6 are operated by transmission from a sewing machine motor M driven according to a drive command from the control unit 2.

FIG. 4 is a time chart showing the contents of the operation which occurs in each part of the sewing machine in accordance with the operation of the control unit 2.
The control unit 2 starts operation in response to turning on the power, constantly monitors the input from the operation pedal 20, and issues a descending command to the output presser foot 22 when the operation pedal 20 is depressed. At the same time, an operation for issuing a drive command to the sewing machine motor M is performed. As a result, the presser foot 22 is lowered onto the needle plate 1, the cloth is clamped between the two, the sewing machine motor M is driven, and the hands 5, 5,. The upper looper and the lower looper 6 operate together with other movable parts such as a feed dog, and the cloth is sewn.

This sewing is stopped by stopping the depression of the operation pedal 20 and returning to the neutral position. At this time, the control unit 2 uses the output of the needle position sensor 21 given to the input side as a feedback signal as the output side sewing machine motor M
A stop command is issued to stop the sewing in a state where the needles 5 and 5 are positioned above the needle plate 1.

After the sewing is stopped, when picking up the sewn fabric, the sewing manufacturer operates the operation pedal 20 to step back. In response to this operation, the control unit 2 issues an ascending command to the presser foot 22 on the output side, separates the presser foot 22 from the needle plate 1, enables the pick-up, and performs the reverse stitching described below in a satisfactory manner. First, an operation command is issued to the output side feeding cylinder 70, and the feeding cylinder 70
After the predetermined time T has elapsed, an operation command is issued to the return cylinder 80 on the output side, and the return cylinder 80 is contracted.

FIG. 5 to FIG. 7 are explanatory views of the procedure for performing reverse stitching in the overlock sewing machine according to the present invention. In the figure, reference numeral 1 denotes a needle plate. The needle plate 1 has the same configuration as the needle plate 1 shown in FIGS. 9 to 13, and has a needle hole 10 opened at a substantially central portion in the front-rear direction, and a female hole opened at a position in front of the needle hole 10. 11
And a plurality of feed holes opening before and after and on one side of the needle hole 10
Needle drop positions A, A corresponding to a pair of left and right needles 5, 5, respectively, are arranged along the front edge inside the needle hole 10, and between the two. In addition, a needle plate middle claw 14 extending from the front edge in the feed direction is provided in a protruding manner. An empty ring holder 15 for cutting and holding an empty ring is provided in front of the needle plate 1 as described later, and a cutting knife 16 for cutting the fabric end is provided inside the knife hole 11. I have.

FIG. 5 shows a state where the preceding fabric K has been sewn. As shown in the figure, the sewing machine motor M is stopped in response to the return of the operation pedal 20 to the neutral position in a state where the sewing end end E of the material K has passed through the needle drop positions A, A as shown in the figure. To end. At the end of the sewing, behind the sewing end end E of the fabric K, an empty ring C in which the needle thread and the looper thread are entangled with the needle plate outer claws 13 and the needle plate middle claws 14 is located on the fabric K side. It is formed in such a manner as to be connected to the regular seam B along the edge. At this time, the pair of left and right hands 5 and 5 are located above the needle plate 1 as described above, and the lower looper 6 that operates in synchronization with these needles is shown in FIG.
As shown partially in the figure, it is located at a position advanced to the right side of the needle drop positions A, A.

When performing the above-described reverse stitching from such a state, the operating pedal 20 is depressed as described above to operate the presser foot so that the sewn cloth K can be picked up.
Then, the fabric K is pulled rearward, and an operation of pulling out the hollow ring C entangled with the outer nail 13 of the needle plate and the middle nail 14 of the needle plate is performed.

At this time, in the overlock sewing machine according to the present invention, the feeding cylinder 70 is extended by the operation of the control unit 2 according to the stepping-back operation, and the needle threads S ₁ and S ₂ are fed by this extension. Thus, the entanglement of the hollow ring C with the needle plate outer nail 13 and the needle plate middle nail 14 is reduced, and the hollow ring C can be reliably pulled out backward. Thus, it is in a state where it is completely extracted from the needle plate inner claws 14 formed shorter than the needle plate outer claws 13. Note that this extraction is performed using the time T secured until the subsequent shortening operation of the return cylinder 80.

After completing the extraction, as shown in FIG. 6, the cloth K is turned from the left side of the needle plate 1 to the front side of the needle drop positions A, A, and the extracted needle plate C is extended while extending the empty ring C. The guide is led to the empty ring holder 15 disposed at the front position of the first position, and the empty ring holder 15 is cut and held.

[0055] In overlock sewing machine according to the present invention this time, the cylinder 80 returns the operation of the control unit 2 after extension of the feed cylinder 70 is made to Chijimitan, looper thread S ₄ is pulled back by this Chijimitan. Accordingly, the air ring C together with the dough K withdrawn backward, the retraction force of the looper thread S ₄ acting through the lower looper 6, the distal end side of the lower looper 6, i.e., biased toward the right side In this state, the cloth K can be turned around the point X deviated to the right side of the claw 14 in the needle plate as shown in FIG. As shown in FIG. 7, the empty ring C held by the needle 15 has a needle plate outer nail 13 and a needle plate middle nail 14.
A holding posture that extends rearward without overlapping the needle drop position A on the right side is obtained.

After the empty ring C is held as described above, as shown in FIG.
When the operation pedal 20 is depressed and operated in this state, the presser foot 22 is lowered onto the needle plate 1 and the sewing machine motor M is driven, and the cloth K '
Is started. At this time, there is no danger that the empty ring C held as described above will be pierced by the needles 5 and 5 descending to the needle drop positions A and A, and the cloth K ' The seam formed along the side edge is reliably sewn.

[0057] Also in overlock sewing machine according to the present invention, the pulling back of the looper thread S ₄ by Chijimitan cylinder 80 back, because performed in the upstream side of the auxiliary thread tension unit 9, the looper thread S ₄ after pullback The tension set by the auxiliary thread tensioner 9 is maintained on the lower looper 6 side. Thus, the dough K 'sewing is no possibility to be started in a state where loose looper thread S _4, the sewing start end E'
Immediately after this, a good seam B can be formed.

FIG. 8 is a perspective view showing the sewn state of the hollow ring C realized by the overlock sewing machine according to the present invention. Empty ring C before sewing start as described above, since held further to the right on the right side of the needle location A, sewn between the sewing line side edges and right by the needle thread S ₂ of the dough K ' It is.

In the above embodiment, the operation of feeding out the needle thread and the operation of pulling back the looper thread are performed by the operation pedal.
The operation is performed as a series of operations separated by a predetermined time T in accordance with the stepping-back operation of 20, for example, a needle thread pay-out operation is performed in response to the stepping-back operation of the operation pedal 20, and then the neutral return. These operations may be individually performed in accordance with respective operations, such as performing a looper yarn pull-back operation in accordance with the operation.

[0060]

As described in detail above, in the overlock sewing machine according to the first aspect of the present invention, the needle on the side of the thread tensioner acts on the needle thread stretched between the needle and the thread tensioner. Equipped with a needle thread feeding means for feeding the thread in an appropriate length, loosening the needle thread on the needle side to alleviate the entanglement of the empty ring with the needle plate claw, and reliably pulling out the empty ring by pulling the preceding fabric backward. And a looper thread return means which acts on the looper thread stretched between the looper and the thread tensioner and pulls the looper thread back to the thread tensioner side. The pulled loop is pulled back toward the looper by the looper thread pulled back, and the holding posture of the preceding fabric after turning forward can be maintained in a proper posture that does not overlap the needle drop position,
It is possible to stably perform reverse stitching in which the empty ring is sewn at the start of sewing of the subsequent fabric.

The overlock sewing machine according to the second aspect of the present invention includes a means for increasing or decreasing the length of the needle thread that is fed by the needle thread feeding means. The overlock sewing machine according to the third aspect of the present invention includes a looper thread returning means. Since the means for increasing or decreasing the return length of the looper thread is provided, by adjusting these increase and decrease, the empty ring can be extracted and the holding position of the empty ring can be more appropriately adjusted.

In the overlock sewing machine according to the fourth aspect of the present invention, since the auxiliary thread tensioner is provided between the looper thread returning means and the looper, the looper thread pulled back by the looper thread returning means is tensioned between the looper thread returning means and the looper. It is possible to maintain the state, and the sewing of the subsequent fabric is not started in a state where the looper thread is loosened, so that the sewing immediately after the start can be performed satisfactorily.

Further, the overlock sewing machine according to the fifth aspect of the present invention is provided with control means for operating the needle thread feeding means and the looper thread return means after the sewing of the preceding fabric is completed. By performing the operation of the preceding fabric that has been sewn accordingly, the empty ring can be extracted and held in an appropriate posture, and the reverse sewing that sew the empty ring to the succeeding fabric can be performed stably. The present invention has an excellent effect, for example,

[Brief description of the drawings]

FIG. 1 is a front view schematically showing a configuration of a main part of an overlock sewing machine according to the present invention.

FIG. 2 is a perspective view of a needle thread feeding device and a looper thread returning device.

FIG. 3 is a block diagram showing a configuration of a control system of the overlock sewing machine according to the present invention.

FIG. 4 is a time chart showing the contents of an operation that occurs in each section of the sewing machine in accordance with the operation of the control unit.

FIG. 5 is an explanatory diagram of a procedure of performing reverse stitching by the overlock sewing machine according to the present invention.

FIG. 6 is an explanatory diagram of a procedure for performing reverse stitching by the overlock sewing machine according to the present invention.

FIG. 7 is an explanatory diagram of a procedure for performing reverse stitching by the overlock sewing machine according to the present invention.

FIG. 8 is a perspective view showing a sewn state of an empty ring realized by the overlock sewing machine according to the present invention.

FIG. 9 is an explanatory diagram of an execution procedure of reverse stitching by the two-needle overlock sewing machine.

FIG. 10 is an explanatory diagram of a procedure for performing reverse stitching using a two-needle overlock sewing machine.

FIG. 11 is an explanatory diagram of an execution procedure of reverse stitching by the two-needle overlock sewing machine.

FIG. 12 is an explanatory diagram of an execution procedure of the reverse stitch by the two-needle overlock sewing machine.

FIG. 13 is an explanatory diagram of an execution procedure of reverse stitching by the two-needle overlock sewing machine.

[Explanation of symbols]

1 Needle plate 2 Control unit 5 Needle 6 Lower looper 7 Needle thread feeding device 8 Looper thread returning device 9 Auxiliary thread tensioner 13 Needle plate outer pawl 14 Needle plate middle pawl 41, 42, 43, 44 Thread tensioner 70 Feeding cylinder 80 cylinder S _1, S ₂ needle thread S ₃ back, S ₄ looper thread

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3B150 AA08 CB06 CB20 CD08 CE01 FC01 FC03 JA02 JA13 LA21 LA84 NA45 NA46 NB14 NB15 NC18 QA04 QA06

Claims (5)

[Claims] A needle stretched between a needle and a thread tensioner in a state where a needle thread and a looper thread are entangled with a needle plate claw provided on one side of a needle plate to form an empty ring. A needle thread feeding means for acting on a thread and feeding the needle thread on the side of the thread tensioner by an appropriate length; and a looper thread on the looper side acting on a looper thread stretched between a looper and a thread tensioner. And a looper thread returning means for pulling back to a side of the thread tensioner. 2. The overlock sewing machine according to claim 1, wherein said needle thread feeding means includes means for increasing / decreasing a feeding length of the needle thread during operation. 3. The overlock sewing machine according to claim 1, wherein said looper thread return means includes means for increasing or decreasing the return length of said looper thread during its operation. 4. An automatic yarn tensioner according to claim 1, further comprising an auxiliary thread tensioner disposed between said looper thread return means and said looper, for applying a clamping resistance to said looper thread. Baroque sewing machine. 5. The sewing operation is stopped in a state where the needle is positioned above the needle plate, and the needle thread and the looper thread are entangled with the needle plate claw provided on one side of the needle plate to form an empty ring. Operating the needle thread feeding means to feed out the needle thread on the side of the thread tensioner, loosening the entanglement of the empty ring with the needle plate claw via the needle thread, and the looper thread returning means. To pull back the looper thread to the side of the thread tensioner and pull and bias the empty ring to one side of the needle plate via the looper thread on the side of the looper. The overlock sewing machine according to any one of claims 1 to 4, further comprising means.