CN106192241B - Looper threading device of circular seam sewing machine - Google Patents

Abstract

The invention can perform threading to the looper well. Is provided with: looper side thread guide paths (10, 20) that guide the looper thread to thread take-out holes at the front ends of the loopers (1, 2); an apparatus side thread guide path (30, 40) having a thread introduction port (311, 411) into which a looper thread is inserted; a positive pressure air supply unit (50) that feeds air at positive pressure to the middle of the device-side line guide path; and a connecting part (60) which connects the looper side thread guide path and the apparatus side thread guide path, wherein a release port (122, 222) for releasing a part of the air at the positive pressure to the outside of the looper side thread guide path is provided at the boundary part of the looper side thread guide path and the apparatus side thread guide path or on the thread release hole side of the boundary part.

Description

Looper threading device of circular seam sewing machine

Technical Field

The invention relates to a looper threading device of a circular seam sewing machine.

Background

A conventional looper sewing machine is equipped with a threading device that guides a looper thread to a thread take-out port of a looper by air.

The threading device is provided with: a looper side thread guide path which guides a looper thread to a thread take-out hole at a front end of the looper; a pump that generates air at a positive pressure; an apparatus side thread guide path having a thread introduction port into which a looper thread is inserted; and a connection pipe that connects the looper-side line guide path and the device-side line guide path by forward and backward movement (see, for example, patent document 1).

In this threading device, the positive pressure air from the pump is sent into the device-side line guide path through a path that merges from the middle of the device-side line guide path, and thereby the suction force from the line introduction port is obtained by setting the upstream side of the merging portion of the device-side line guide path to a low pressure state.

When the looper thread is guided, the looper thread guide path and the apparatus thread guide path are connected by the connecting pipe, and the looper thread inserted into the thread inlet is fed to the thread take-out hole of the looper by feeding positive pressure air from the pump into the apparatus thread guide path.

Patent document 1: japanese patent No. 3355214

However, in the conventional threading device described above, the looper-side guide path is connected to the small-diameter thread take-out hole of the looper, and therefore, the flow resistance increases on the looper-side guide path side.

Therefore, if the looper side line guide path and the apparatus side line guide path are connected by the connecting pipe, air that has not completely flowed into the looper side line guide path flows back to the line inlet side, and the looper line is extruded, and the looper line cannot be guided to the line outlet hole of the looper.

Disclosure of Invention

The invention aims to guide a looper line to a looper well.

In order to achieve the above object, the present invention has any one of the following features (1) to (4).

(1)

A looper threading device of a circular seam sewing machine is provided with:

a looper side thread guide path which guides a looper thread to a thread take-out hole at a front end of the looper;

an apparatus side thread guide path having a thread introduction port into which a looper thread is inserted;

a positive pressure air supply unit that sends air at a positive pressure to the middle of the apparatus-side line guide path; and

a connecting portion that connects the looper-side wire guide path and the apparatus-side wire guide path,

a discharge port for discharging a part of the positive pressure air to the outside of the looper-side thread guide path is provided at a boundary portion between the looper-side thread guide path and the apparatus-side thread guide path or on the thread discharge hole side of the boundary portion.

(2)

The looper threading device of a loop sewing machine according to the above (1),

the discharge port is any of a slit, a through hole, a plurality of small holes, and a mesh.

(3)

The looper threading device of a loop sewing machine according to the above (1) or (2),

the relief port is formed at a connecting end portion on the apparatus-side wire guide path side in the looper-side wire guide path or a connecting end portion on the looper-side wire guide path side in the apparatus-side wire guide path.

(4)

The looper threading device of a loop sewing machine according to the above (3),

a connecting end portion of the looper-side guide path on the apparatus-side guide path side or a connecting end portion of the looper-side guide path on the apparatus-side guide path side is configured to be inserted and connected into a connecting end portion of a guide path on the other side,

the release opening is a slit having a shape recessed in the direction of insertion.

ADVANTAGEOUS EFFECTS OF INVENTION

In the looper threading device of a loop sewing machine according to the present invention, the release port for releasing a part of the air at the positive pressure to the outside of the looper-side thread guide path is provided at the boundary portion between the looper-side thread guide path and the device-side thread guide path or on the thread take-out hole side of the boundary portion.

Drawings

Fig. 1 is a perspective view of the looper threading device according to the present embodiment.

Fig. 2 is a perspective view showing a state where the connection pipe of the apparatus-side line guide path is located at a non-connection position.

Fig. 3 is a perspective view showing a state where the connection pipe of the apparatus-side line guide path is located at the connection position.

Fig. 4 is an oblique view of a connecting pipe of a looper-side wire guide path formed with a relief port.

Fig. 5 is a side view of a connecting pipe of a looper-side thread guide path formed with a relief port.

Fig. 6 is a side view showing a state in which the connecting pipe of the looper-side guide path and the connecting pipe of the apparatus-side guide path are connected.

Fig. 7 is a sectional view showing the arrangement of the first and second apparatus-side line guide paths of the support block by a section along the X-Z plane.

Fig. 8 is an exploded perspective view of the structure of the support block and a part of the side line guide paths of the first and second apparatuses.

Fig. 9 is a perspective view of the lower end of the introducing member of the apparatus-side wire guide path.

Fig. 10 is a cross-sectional view of the lower end portion of the introducing member of the apparatus side guide path.

Fig. 11 is a sectional view of a connection portion between the connection pipe of the looper side wire guide path and the connection pipe of the apparatus side wire guide path.

Fig. 12 is a cross-sectional view of a connecting portion between the connecting pipe of the looper-side guide path and the connecting pipe of the apparatus-side guide path, which is virtually illustrated in the case where the relief port is not formed.

Description of the reference numerals

1 lower looper

2 go up looper ware

10 first looper side line guide path

11 guide tube

12 connecting pipe (connecting end)

121 conical surface

122 release port

20 second looper side line guide path

21 guide tube

22 connecting pipe (connecting end)

221 conical surface

222 discharge port

30 first device side line guide path

31 introduction member

311 thread lead-in port

32 guide tube

321 conical part

33 connecting pipe

40 second apparatus side line guide path

41 introduction part

411 thread introducing port

42 guide tube

421 conical part

43 connecting pipe

50 positive pressure air supply part

60 connecting part

61 support bracket

100 threading device

Detailed Description

[ overall Structure of embodiment ]

A looper threading device 100 mounted on a lockstitch sewing machine as a circular seam sewing machine according to an embodiment of the present invention will be described with reference to fig. 1 to 12. Fig. 1 is an oblique view of a looper threading device 100. In fig. 1, the Z-axis direction represents a vertical up-down direction, the X-axis direction represents a horizontal direction in which the cloth is conveyed, and the Y-axis direction represents a horizontal direction orthogonal to the X-axis direction. The side of the longitudinal body of the sewing machine in the Y-axis direction may be referred to as the rear side, and the side of the face may be referred to as the front side.

The sewing machine for overlock sewing is provided with a lower looper 1 and an upper looper 2 which are provided on the lower side of a needle plate and reciprocate in synchronization with the vertical movement of a needle bar having a sewing needle.

The looper 1 has a thread take-out hole for taking out a looper thread at a sharp rear end portion, and captures the thread loop from the needle by reciprocating the front end portion forward and backward.

The upper looper 2 has a thread drawing hole for drawing the upper looper thread at a sharp front end portion facing obliquely upward in the forward direction, and captures the thread loop of the lower looper thread from the lower looper 1 by reciprocating the front end portion obliquely upward in the forward direction and obliquely downward in the rearward direction. When the upper looper 2 moves obliquely forward, the front end thereof reaches the upper side from the edge of the cloth to be sewn, and at this time, the sewing needle is caught by being projected into the loop of the upper looper thread formed by the upper looper 2.

That is, the lockstitch sewing machine performs lockstitch sewing by the cooperation of the sewing needle, the lower looper 1, and the upper looper 2.

[ threading device of looper ]

The looper threading device 100 includes: a first looper side thread guide path 10 that guides a looper thread to a thread take-out hole at the front end of the lower looper 1; a second looper side thread guide path 20 which guides the looper thread to the thread take-out hole at the front end of the upper looper 2; a first apparatus side thread guide path 30 having a thread introduction port 311 into which a lower looper thread is inserted; a second apparatus side thread guide path 40 having a thread introduction port 411 into which an upper looper thread is inserted; a positive pressure air supply unit 50 for sending air at positive pressure to the middle of the first and second device- side guide paths 30 and 40; and a connecting portion 60 that connects the first looper-side wire guide path 10 and the first apparatus-side wire guide path 30, and connects the second looper-side wire guide path 20 and the second apparatus-side wire guide path 40.

[ first looper side line guide route ]

Fig. 2 is an enlarged oblique view of the first and second looper-side thread guide paths 10, 20 in a non-connected state with the first and second apparatus-side thread guide paths 30, 40, and fig. 3 is an enlarged oblique view of a connected state.

As shown in fig. 1 to 3, the first looper side guide path 10 is provided so as to be embedded in a groove formed on one surface side in the X-axis direction of the lower looper 1, and the first looper side guide path 10 includes: a partially bent tubular guide tube 11, and a straight cylindrical connection tube 12 communicating with the guide tube 11.

One end of the guide tube 11 is connected to a wire drawing port at the front end of the lower looper 1, and the other end is connected to the front end of the connection tube 12. Both the guide tube 11 and the connection tube 12 have a threading hole formed in the entire length thereof so as to penetrate the center thereof, and the threading holes communicate with each other.

The connection pipe 12 is fixedly supported near the base end portion of the lower looper 1, and the rear end portion thereof can be connected to the first apparatus-side guide path 30.

Further, the first looper side thread guide path 10 reciprocates together with the lower looper 1 during sewing, but when the lower looper is connected to the first device side thread guide path 30 to pass the lower looper thread, the lower looper 1 is at a predetermined stop position, and the state of the connecting tube 12 in the Y axis direction is maintained.

Fig. 4 is a perspective view of the connection pipe 12, fig. 5 is a side view, and fig. 6 is a side view of the connection pipe 12 in a state where the connection pipe 33 of the first apparatus-side guide path 30, which will be described later, is inserted.

As shown in fig. 4 and 5, the outer diameter of the front end of the connection pipe 12 is smaller than the outer diameter of the rear end, and the outer periphery of the small-diameter front end is supported by the lower looper 1.

The rear end portion of the connection pipe 12 is opened to a large extent and gradually becomes narrower toward the front. That is, a mortar-shaped conical surface 121 is formed at the rear end of the connecting pipe 12, and the connecting pipe 33 of the first device-side line guide path 30 inserted from the rear can be guided to the center of the connecting pipe 12.

A slit-shaped release opening 122 is formed in the rear end portion of the connection pipe 12 in the radial direction of the connection pipe 12. As shown in fig. 5, the release opening 122 is formed in a concave shape from the rear end surface of the connection pipe 12 toward the connection pipe 33 inserted into the first apparatus-side guide path 30. As shown in fig. 6, the depth of the release port 122 is set such that the bottom surface of the release port 122 is slightly forward of the distal end portion of the connection pipe 33 of the first apparatus-side guide path 30 inserted into the connection pipe 12, and a gap S is formed between the connection pipe 12 and the connection pipe 33 of the first apparatus-side guide path 30, and this gap S discharges a part of the positive pressure air that is forced to the lower looper wire to the outside.

The operation and effect of the release port 122 will be described later.

[ second looper side line guide route ]

The structure and the structure of the second looper-side guide path 20 are similar to those of the first looper-side guide path 10, and the description of the same structure as that of the first looper-side guide path 10 may be omitted.

As shown in fig. 1 to 3, the second looper side guide path 20 is provided to be embedded in a groove formed on one surface side in the X axis direction of the upper looper 2, and the second looper side guide path 20 includes: a partially bent tubular guide tube 21, and a straight cylindrical connection tube 22 communicating with the guide tube 21.

One end of the guide pipe 21 is connected to a wire drawing port at the front end of the upper looper 2, and the other end is connected to the front end of the connection pipe 22. Both the guide tube 21 and the connection tube 22 have a threading hole formed in the entire length thereof so as to pass through the center thereof, and the threading holes communicate with each other.

The connection pipe 22 is fixedly supported near the base end portion of the upper looper 2, and its rear end portion is connectable to the second apparatus-side wire guide path 40.

The second looper thread guide path 20 reciprocates together with the upper looper 2 during sewing, but the upper looper 2 is at a predetermined stop position when the upper looper thread is passed through, and the state of the connecting pipe 22 along the Y axis direction is maintained.

The outer diameter of the front end portion of the connection pipe 22 is smaller than the outer diameter of the rear end portion, and the small-diameter front end portion is supported by the upper looper 2. Further, the same point as the connection pipe 12 is that a mortar-shaped conical surface 221 is provided at the rear end of the connection pipe 22, and a slit-shaped release port 222 is formed.

Although not shown, the depth of the release port 222 is set so that the bottom surface of the release port 222 is slightly forward of the distal end portion of the connecting pipe 43 of the second apparatus-side guide path 40 inserted into the connecting pipe 22, and a gap S (see fig. 6) is formed to discharge a part of the positive pressure air pressure-fed to the upper looper to the outside.

[ Positive pressure air supply part ]

As shown in fig. 1, the positive pressure air supply unit 50 includes: a support block 51 fixedly mounted on an upper portion of a base portion of a frame of a lockstitch sewing machine; a pump 52 having the support block 51 built therein; a motor 53 serving as a drive source of the pump 52; and a cover 54 mounted on an upper portion of the support block 51.

The output shaft of the motor 53 is connected to a drive unit of the pump 52.

The pump 52 includes an intake port and an exhaust port, and the exhaust port is connected to a conduction path 516 formed in the support block 51. Then, the positive pressure air generated by the operation of the pump 52 is supplied to the conduction path 516.

The pump 52 may be of any form as long as it is a small-sized structure that can be incorporated in a lockstitch sewing machine.

Fig. 7 is a sectional view showing the arrangement position of the first and second apparatus- side guide paths 30, 40 of the support block 51 by a section along the X-Z plane, and fig. 8 is an exploded perspective view of the structure of the support block 51 and a part of the first and second apparatus- side guide paths 30, 40.

As shown in fig. 7 and 8, the support block 51 has two through holes 511 and 511 formed vertically therethrough for holding the structures of the first and second apparatus side thread guide paths 30 and 40 on the thread introduction ports 311 and 411 side, respectively.

In each through hole 511, a large diameter portion 512, an equal diameter portion 513, a tapered portion 514, and a small diameter portion 515 are concentrically connected in this order from above, wherein the large diameter portion 512 has the largest inner diameter, the equal diameter portion 513 has a slightly smaller inner diameter than the large diameter portion 512, the tapered portion 514 is conical, and gradually decreases in diameter downward, and the small diameter portion 515 has the smallest inner diameter.

Further, the support block 51 is formed with a conduction path 516, and the conduction path 516 guides the positive pressure air generated from the pump 52 to the lower portion of the large diameter portion 512 of each through hole 511. The positive pressure air from the pump 52 can be supplied into the first and second device- side guide paths 30 and 40 through the conduction path 516.

The cover 54 is a rectangular flat plate and is attached to the upper surface of the support block 51. In the cover 54, openings 541 and 541 are formed to penetrate vertically at positions corresponding to the two through holes 511 and 511 of the support block 51. The openings 541, 541 have a diameter slightly smaller than the large diameter portions 512, 512 of the through holes 511, and are configured to expose the thread introduction ports 311, 411 of the first and second apparatus thread guide paths 30, 40 upward.

In addition, a threading start button 542 is provided near the rear end of the cover 54. When the threading start button 542 is pressed, the motor 53 starts driving, the pump 52 operates, and the lower looper and the upper looper can be threaded from the first and second device thread guide paths 30 and 40 by air.

[ first and second device side guide paths ]

As shown in fig. 1, 7, and 8, the first apparatus-side guide path 30 includes: an introduction member 31 having a thread introduction port 311 for a lower looper thread; a tubular guide tube 32 having an upper end coupled to the introduction member 31; and a tubular connection pipe 33 connected to the lower end of the guide pipe 32 so as to be movable back and forth.

The second apparatus-side guide path 40 includes: an introduction member 41 having a thread introduction port 411 for winding a thread; a tubular guide tube 42 having an upper end portion connected to the introduction member 41; and a tubular connection pipe 43 connected to the lower end of the guide pipe 42 to be movable back and forth.

The upper end portions of the introduction member 31 and the guide pipe 32 of the first apparatus-side guide path 30 and the upper end portions of the introduction member 41 and the guide pipe 42 of the second apparatus-side guide path 40 have the same structure, and therefore are shown in common in fig. 7.

That is, both the guide tubes 32 and 42 are arranged in the Z-axis direction with one end facing upward, the middle portion thereof being bent, and the other end facing forward being arranged in the Y-axis direction.

The outer diameters of the one end portions of the guide tubes 32 and 42 substantially match the inner diameters of the small diameter portions 515 of the through holes 511, and conical portions 321 and 421 whose diameters are increased upward are formed at the one end portions of the guide tubes 32 and 42.

The inclination angle of the conical portions 321 and 421 coincides with the inclination angle of the tapered portion 514 of the through hole 511, and the outer peripheral surfaces of the conical portions 321 and 421 are in close contact with the tapered portion 514 of the through hole 511 without a gap with respect to the guide tubes 32 and 42 inserted into the through hole 511 from above.

The lower end portions of the introduction members 31 and 41 are disposed inside the through holes 511 in a state of being inserted into the conical portions 321 and 421 of the guide tubes 32 and 42.

Further, circular flange portions 312 and 412 extending radially outward are formed on the outer peripheral surfaces of the introduction members 31 and 41. When the introduction members 31 and 41 are disposed inside the through hole 511, the flange portions 312 and 412 are located near the lower end of the large diameter portion 512 of the through hole 511.

Further, O-rings 34 and 44 as sealing materials are disposed above the flange portions 312 and 412 of the introduction members 31 and 41.

The O-rings 34 and 44 are in close contact with the inner peripheral surface of the large diameter portion 512 of the through hole 511 and the outer peripheral surfaces of the introduction members 31 and 41, and divide the inner space of the large diameter portion 512 into two upper and lower parts in an airtight state.

Therefore, the positive pressure air supplied from the conduction path 516 communicating with the lower portion of the large diameter portion 512 is supplied only to the lower side of the O-rings 34 and 44, and the leakage to the upper side is prevented.

Further, the outer diameters of the O-rings 34, 44 are larger than the inner diameter of the opening 541 of the cover 54, and when the cover 54 is fixed to the upper surface of the support block 51, the introduction members 31, 41 can be held from above via the O-rings 34, 44 and the flange portions 312, 412.

As shown in fig. 9 and 10, conical surfaces 314 and 414, which are reduced in diameter downward, are formed at the lower end portions of the introduction members 31 and 41. The inclination angle of the conical surface 314, 414 matches the conical shape 321, 421 of the guide tube 32, 42 described above, and the conical surface 314, 414 of the introduction member 31, 41 can be brought into close contact with the inner surface of the conical shape 321, 421 without a gap.

Further, a plurality of vent grooves 313, 413 are formed in the conical surfaces 314, 414 of the introduction members 31, 41 in the vertical direction.

Therefore, if air of positive pressure is supplied from the conduction path 516 into the through hole 511, the air of positive pressure enters the guide pipes 32 and 42 through the plurality of ventilation grooves 313 and 413, and an air flow directed downward is generated below the point of confluence between the guide pipes 32 and 42 and the plurality of ventilation grooves 313 and 413.

As a result, the thread introduction ports 311 and 411 and the threading holes of the introduction members 31 and 41 positioned above the point of confluence between the guide tubes 32 and 42 and the plurality of ventilation grooves 313 and 413 are subjected to a reduction in air pressure according to bernoulli's law, and a downward suction force is generated from the thread introduction ports 311 and 411.

As described above, the guide tubes 32 and 42 are supported at one end by the support block 51, have a shape along the Z-axis direction, have a middle portion bent, and have the other end directed forward in the Y-axis direction.

The other end portions of the guide pipes 32 and 42 are fixedly supported by a fixing bracket 72, and the fixing bracket 72 is attached to a main body plate 71 fixedly provided in a base portion of the sewing machine.

Further, connection pipes 33 and 43 each formed of a straight cylinder are attached to the other end portions of the guide pipes 32 and 42. The connecting pipes 33, 43 have inner diameters substantially equal to the outer diameters of the other end portions of the guide pipes 32, 42, and the other end portions of the guide pipes 32, 42 are inserted inside and slidable with respect to the guide pipes 32, 42.

That is, the connection pipes 33 and 43 can reciprocate in the Y-axis direction.

The connection pipes 33 and 43 of the first and second apparatus- side guide paths 30 and 40 are arranged concentrically with the connection pipes 12 and 22 of the first and second looper- side guide paths 10 and 20 when the lower looper 1 and the upper looper 2 are at predetermined stop positions.

Further, if the connecting pipes 33 and 43 are moved forward from the non-connecting position (fig. 2) to the connecting position (fig. 3), the tip end portions thereof can be inserted into the conical surfaces 121 and 221 of the connecting pipes 12 and 22 of the first and second looper- side guide paths 10 and 20, and can be connected to each other by this insertion.

[ connecting part ]

As shown in fig. 1, the connection portion 60 includes: a support bracket 61 that supports the connection pipes 33, 43 movably forward and backward; a movable plate 62 that holds the connection pipes 33 and 43 and is supported slidably in the front-rear direction with respect to the main body plate 71; an extension spring 63 that applies forward movement to the movable plate 62; an operation lever 64 that inputs a forward and backward movement to the movable plate 62; and a stopper pin 65 that defines the position of each looper 1, 2 when moving from the non-connected position to the connected position.

The support bracket 61 is plate-shaped, has two support holes into which the connection pipes 33 and 43 can be inserted in wall surfaces along the X-Z plane, which are vertically erected from the main body plate 71 along the Y-Z plane, and can move the connection pipes 33 and 43 forward and backward by sliding with respect to the support holes.

The movable plate 62 has a support wall 621 that is formed by bending and raising the front end of a long flat plate in the Y-axis direction.

The support wall 621 supports the connection pipes 33 and 43 slidably in the front-rear direction by passing the connection pipes 33 and 43 through the support wall along the X-Z plane. The fastening rings 624 and 624 are provided in the connection pipes 33 and 43, and when moving from the connection position to the disconnection position, the support wall 621 moving to the rear engages with the fastening rings 624 and 624, thereby moving the connection pipes 33 and 43 rearward. The pressing springs 623, which are weaker than the tension spring 63, abut against the tightening rings 624, and the connection pipes 33, 43 are biased forward through the tightening rings 624, 624. That is, the connection pipes 33 and 43 can move in accordance with the forward and backward movement of the movable plate 62.

One end of the tension spring 63 is coupled to the movable plate 62, and the other end is coupled to the support bracket 61. Accordingly, the movable plate 62 is always tensioned forward, and the connection pipes 33 and 43 are connected to the connection pipes 12 and 22 of the first and second looper- side guide paths 10 and 20 in a state where the movable plate 62 is not restrained.

The operation lever 64 is supported rotatably about the X axis with respect to the main body plate 71, and a cam member 641 that rotates simultaneously is attached to the operation lever 64. The cam member 641 is provided with a projection 642 projecting outward in the rotational radius direction thereof, and the cam member 641 is disposed such that the projection 642 abuts against a protruding portion 622 provided at the rear end portion of the movable plate 62 from the front.

Then, if the operating lever 64 is rotated in the clockwise direction in fig. 1, the protrusion 642 of the cam member 641 moves the movable plate 62 to the rear via the convex portion 622, and if the operating lever 64 is rotated in the counterclockwise direction in fig. 1, the pressing by the cam member 641 is released, and the movable plate 62 is moved to the front by the tension of the tension spring 63. That is, the connection pipes 33 and 43 are moved forward and backward by the rotational operation of the operating lever 64, and the connection state and the disconnection state of the connection pipes 33 and 43 of the first and second apparatus- side guide paths 30 and 40 with respect to the connection pipes 12 and 22 of the first and second looper- side guide paths 10 and 20 can be switched.

The stopper pin 65 is movable in the X axis direction, and one end portion thereof is biased by a screw, not shown, so as to project toward the cam member 641, and if the operating lever 64 is rotated counterclockwise, the stopper pin 65 is pressed inward by an inclined surface, not shown, of the cam member 641.

A threading positioning collar (not shown) is fixed to a driving shaft that imparts reciprocating motion to each looper 1, 2, and the other end of the stopper pin 65 is engageable with the outer peripheral surface of the threading positioning collar. A recess is provided at one location on the outer peripheral surface of the threading positioning collar, and if the stopper pin 65 is pushed into the recess by rotating the operating lever 64 counterclockwise, the drive shaft is fixed, and the loopers 1 and 2 can be stopped at predetermined stop positions.

That is, the stopper pin 65 is pushed in by rotating the operating lever 64 counterclockwise, the upper looper 2 and the lower looper 1 are fixed at predetermined stop positions, and the connection pipes 33 and 43 can be connected to the connection pipes 12 and 22 at appropriate positions.

[ operation of looper threading device ]

When the operating lever 64 is rotated counterclockwise, the cam member 641 pushes the stopper pin 65 inward to fix the lower looper 1 and the upper looper 2 at the predetermined stop positions. Accordingly, the connection pipe 12 of the first looper-side guide path 10 and the connection pipe 22 of the second looper-side guide path 20 are in a state of being along the Y-axis direction, and are fixed at positions where they can be connected to the connection pipe 33 of the first apparatus-side guide path 30 and the connection pipe 43 of the second apparatus-side guide path 40.

Then, the movable plate 62 moves forward by the counterclockwise rotation of the operating lever 64, and the connection pipe 33 of the first apparatus-side line guide path 30 and the connection pipe 43 of the second apparatus-side line guide path 40, which are biased by the pressing springs 623 and 623, move forward in accordance with the movement of the movable plate 62.

Thereby, the connection pipes 33 and 43 of the first and second apparatus- side guide paths 30 and 40 are switched from the non-connected state of fig. 2 to the connected state of fig. 3, the connection pipes 33 and 43 are inserted into the conical surfaces 121 and 221 of the connection pipes 12 and 22 of the first and second looper- side guide paths 10 and 20, respectively, the connection pipe 33 and the connection pipe 12 are connected, and the connection pipe 43 and the connection pipe 22 are connected.

When the start button 542 is pressed, the motor 53 and the pump 52 start driving, and air of positive pressure flows into the guide pipes 32 and 42 from the ventilation grooves 313 and 413 at the lower ends of the introduction members 31 and 41 through the conduction path 516 as shown in fig. 7. This generates a suction force in the thread introducing ports 311, 411 of the introducing members 31, 41.

Then, the air at the positive pressure is supplied to the string drawing hole of the lower looper 1 through the first apparatus-side line guide path 30 and the first looper-side line guide path 10, and the air at the positive pressure is supplied to the string drawing hole of the upper looper 2 through the second apparatus-side line guide path 40 and the second looper-side line guide path 20.

At this time, the respective looper- side guide paths 10, 20 become larger in flow resistance than the respective apparatus- side guide paths 30, 40 due to the following reasons and the like: the wire drawing-out openings of the loopers 1 and 2 are small; and the guide pipes 11, 21 of the looper thread guide paths 10, 20 are provided along the loopers 1, 2, and therefore, a thinner pipe is used so as not to hinder thread catching.

Therefore, the connection portion between the connection pipe 33 and the connection pipe 12 and the connection portion between the connection pipe 43 and the connection pipe 22, which are boundaries thereof, may cause difficulty in smooth inflow of air.

As shown in fig. 12, if the release port is not formed at the connection part between the connection pipes 33 and 43 and the connection pipes 12 and 22, there is no release passage for excess air, and thus the internal pressure of the first device side line guide paths 30 and 40 becomes high, and there is a possibility that air flows backward from the line introduction ports 311 and 411 of the introduction members 31 and 41 to the outside. However, as shown in fig. 11, since the discharge ports 122 and 222 are formed at the rear end portions of the connection pipes 12 and 22, excess air is discharged from the discharge ports 122 and 222 to the outside of the first and second looper- side guide paths 10 and 20.

Therefore, the suction force is favorably maintained at the thread introducing ports 311, 411 of the introducing members 31, 41, and if the lower looper thread is inserted from the thread introducing port 311, the thread can be smoothly fed to the thread take-out hole of the lower looper 1 to thread the lower looper thread. Similarly, if the upper looper thread is inserted from the thread introducing port 411, the thread can be smoothly fed to the thread extracting hole of the upper looper 2 to thread the upper looper thread.

After the threading is completed, if the start button 542 is canceled from being pressed, the motor 53 and the pump 52 are stopped from being driven, and the supply of the positive pressure air is stopped.

Then, if the operating lever 64 is rotated clockwise, the connecting pipes 33 and 43 are separated from the connecting pipes 12 and 22 and retracted.

Then, the state of pushing the stopper pin 65 into the concave portion of the positioning collar by the cam member 641 is released. Thus, the restriction state of the drive shaft is released, the loopers 1 and 2 can be operated, and the lockstitch sewing machine can perform sewing.

[ technical effects of the embodiments ]

In the threading device 100 of the lockstitch sewing machine, the release ports 122 and 222 for releasing a part of the air at the positive pressure to the outside of the first and second looper side guide paths 10 and 20 are provided at the rear end of the connection pipe 12 which is the boundary between the first looper side guide path 10 and the first device side guide path 30 and the rear end of the connection pipe 22 which is the boundary between the second looper side guide path 20 and the second device side guide path 40.

Therefore, even when an excessive amount of air of positive pressure is supplied to the first and second looper side guide paths 10 and 20, the air can be discharged to the outside through the release ports 122 and 222, and the reverse flow of air from the thread introduction ports 311 and 411 of the introduction members 31 and 41 can be suppressed, so that satisfactory threading can be performed.

Further, since the release ports 122 and 222 are provided at the boundary portion between the first looper-side guide path 10 and the first apparatus-side guide path 30 and the boundary portion between the second looper-side guide path 20 and the second apparatus-side guide path 40, it is possible to efficiently discharge the excess air in accordance with the position where the flow resistance of the air becomes high, and it is possible to sufficiently suppress the reverse flow of the air from the thread introduction ports 311 and 411, thereby performing more satisfactory threading.

Further, since the discharge ports 122 and 222 are formed by slits, the formation is easy, and the production cost of the apparatus can be reduced, the productivity can be improved, and the like.

The connection pipes 33 and 43 of the apparatus- side guide paths 30 and 40 are inserted into and connected to the connection pipes 12 and 22 of the looper- side guide paths 10 and 20, and the release openings 122 and 222 are slits each having a shape recessed in the direction of insertion. Therefore, the opening amount of the release ports 122 and 222 can be easily adjusted according to the depth of insertion of the connection pipes 33 and 43 into the connection pipes 12 and 22, and the amount of air discharge can be optimized, so that the occurrence of air blow-out from the thread introduction ports 311 and 411 can be further suppressed, and more satisfactory threading can be performed.

[ others ]

The release ports 122 and 222 need not be slits as long as they have a structure capable of discharging excess air to the outside. For example, a through hole or a plurality of small holes may be provided to pass through the inside of the connection pipe 12 or 22 to the outside, or a peripheral wall on the rear end side of the connection pipe 12 or 22 may be formed in a mesh.

The release ports 122 and 222 may be formed at the distal end side of the connection pipes 33 and 43 of the apparatus- side guide paths 30 and 40.

Further, the outer diameter of the connection pipes 33, 43 may be increased as compared with the connection pipes 12, 22, a conical surface may be formed at the tip end portions of the connection pipes 33, 43, and the rear end portions of the connection pipes 12, 22 may be inserted into the conical surface of the connection pipes 33, 43.

The discharge ports 122 and 222 are not limited to the boundary positions between the looper- side guide paths 10 and 20 and the apparatus- side guide paths 30 and 40, and may be provided closer to the thread discharge ports of the loopers 1 and 2. That is, the looper side guide paths may be provided midway along the looper side guide paths 10 and 20. In this case, too, the excessive positive pressure air can be discharged to the outside of the looper- side guide paths 10 and 20, and the excellent threading can be performed.

Further, although the above-described threading device 100 is described as being mounted on the overlock sewing machine, the looper thread may be threaded through a thread take-out hole of a looper of another looper sewing machine, for example, a double-looper sewing machine. In this case, since the looper is not mounted on the double-looper sewing machine, the threading is performed only on the lower looper.

Claims (1)

1. A looper threading device of a circular seam sewing machine is provided with:

a looper side thread guide path which guides a looper thread to a thread take-out hole at a front end of the looper;

an apparatus side thread guide path having a thread introduction port into which a looper thread is inserted;

a positive pressure air supply unit that sends air at a positive pressure to the middle of the apparatus-side line guide path; and

a connecting portion that connects the looper-side wire guide path and the apparatus-side wire guide path,

a discharge port for discharging a part of the positive pressure air to the outside of the looper-side thread guide path is provided at a boundary portion between the looper-side thread guide path and the apparatus-side thread guide path or on the thread discharge hole side of the boundary portion,

the relief port is formed at a connecting end portion on the apparatus-side wire guide path side in the looper-side wire guide path or a connecting end portion on the looper-side wire guide path side in the apparatus-side wire guide path,

the connecting end portion of the looper-side guide path on the apparatus-side guide path side or the connecting end portion of the looper-side guide path on the looper-side guide path side is configured to be switchable between a non-connected state and a connected state, and to be connected by inserting the connecting end portion of the guide path on the other side when switched to the connected state,

the release opening is a slit having a shape recessed in the direction of insertion.

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