CN221142096U - Little bird nest thread cutting induced draft mechanism and sewing machine - Google Patents

Abstract

The utility model provides a small bird nest thread cutting air suction mechanism and a sewing machine, comprising an auxiliary knife, a movable knife and an air suction pipe, wherein the movable knife is provided with a thread cutting edge for starting a seam, a thread cutting edge for cutting after the seam and a thread hooking groove for allowing a needle in the sewing machine to pass through; when the sewing machine starts the seam, the air suction inlet is used for picking up the upper thread end and the lower thread end, and enabling the lower thread end to incline downwards, and the thread cutting edge of the starting seam can be meshed with the auxiliary knife to cut the thread end of the thread; when the sewing machine finishes sewing, the cutting edge of the shearing line after sewing can be meshed with the auxiliary knife to cut the surface line and the bottom line, and the air suction inlet is used for picking up the thread end of the bottom line and enabling the thread end of the bottom line to incline downwards. According to the utility model, the bottom thread head is caught through the air suction inlet, so that the bottom thread head is inclined downwards after sewing and during starting, and the upper thread loop is easier to wind the bottom thread after passing through the air suction inlet during starting, thereby being beneficial to taking the bottom thread.

Description

Little bird nest thread cutting induced draft mechanism and sewing machine

Technical Field

The utility model relates to the technical field of sewing machines, in particular to a thread cutting and air suction mechanism with less bird nests and a sewing machine.

Background

The lockstitch sewing machine is a sewing machine capable of forming lockstitch, is widely applied to various sewing process scenes, and can meet the sewing requirements of various fabrics. However, in the process of forming the primary lock stitch, the lockstitch machine often brings the bottom thread under the stitching material, and the bottom thread is interweaved and wound, and the length of the upper thread brought down is different, so that the scope of interweaving and winding under the lockstitch machine is different, and the characteristics are changed into a bird nest in the industry. Bird nest formed by the first part of the sewing is unattractive and is not accepted, especially for high quality clothing. At present, the following two methods are available for processing bird nests in the early stage of sewing.

The manual removal is carried out in the first mode, but the labor intensity of workers is greatly increased in the first mode, the labor cost is high, the input cost is high, the waste time is high, and the efficiency is low.

And a second mode adopts a bird nest less thread cutting device which is used for cutting thread heads of the section thread during the seam starting and cutting the bottom thread and the upper thread after the sewing is finished. However, after the thread is cut at the end of sewing, the position of the end of the bottom thread in the rotating shuttle is not fixed, and when the end of the bottom thread is deviated from the upper thread loop, the bad phenomenon that the bottom thread is not lifted by the lifting belt easily occurs, the formation of the thread trace is affected, and the sewing quality is reduced.

Therefore, the technology and method for removing bird nests or less bird nests in the market at present cannot well meet the requirements of customers on sewing quality.

Disclosure of utility model

In view of the above-mentioned drawbacks of the prior art, the present utility model aims to provide a small bird nest and line shearing air suction mechanism, which can not only realize small bird nest for seam lifting, but also reliably ensure normal formation of seam lifting.

In order to achieve the above purpose, the utility model provides a small bird nest thread cutting air suction mechanism, which comprises an auxiliary knife, a movable knife capable of moving towards or away from the auxiliary knife, and an air suction pipe fixedly arranged, wherein the movable knife is provided with a seam lifting thread cutting edge, a seam post-cutting edge and a seam lifting thread hooking groove allowing a needle in a sewing machine to pass through;

When the sewing machine starts the seam, the air suction inlet is used for picking up the upper thread end and the lower thread end, and enabling the lower thread end to incline downwards, and the thread cutting edge of the starting seam scissors can be meshed with the auxiliary knife to cut the thread end of the thread;

When the sewing machine finishes the sewing, the shearing edge after the sewing can be meshed with the auxiliary knife to shear the surface line and the bottom line, and the air suction inlet is used for picking up the thread end of the bottom line and enabling the thread end of the bottom line to incline downwards.

Further, the air suction inlet is arranged close to the release side of the upper thread loop on the rotating shuttle.

Further, the movable knife is also provided with an avoidance needle passing groove which allows a needle in the sewing machine to pass through;

When the movable knife moves to enable the avoidance needle passing groove to be located right below the needle, the stitching scissors line cutting edge is close to the auxiliary knife but is not meshed with the auxiliary knife.

Further, the small bird nest line shearing and air suction mechanism further comprises a line pressing plate which is fixedly arranged, a first line clamping part is arranged on the surface of the movable knife, and a second line clamping part is arranged on the line pressing plate;

When the movable knife moves to enable the avoidance needle passing groove to be located right below the needle, a thread clamping seam for clamping the upper thread end is formed between the first thread clamping portion and the second thread clamping portion.

Further, a first wire clamping part is arranged on the surface of the movable knife, and a third wire clamping part is arranged on the auxiliary knife;

When the movable knife moves to enable the avoidance needle passing groove to be located right below the needle, a thread clamping seam for clamping the upper thread end is formed between the first thread clamping portion and the third thread clamping portion.

Further, the movable knife is rotatably assembled below the sewing machine bottom plate, and the auxiliary knife is fixed at the bottom of the sewing machine bottom plate.

Further, the movable knife is rotatably mounted under the sewing machine base plate, and the auxiliary knife is movably mounted under the sewing machine base plate.

Further, the movable knife and the auxiliary knife are both rotatably mounted under the sewing machine base plate.

Further, the bird nest less line cutting and air sucking mechanism further comprises a line cutting driving motor, a first line cutting cam, a second line cutting cam, a first transmission mechanism and a second transmission mechanism, wherein the first line cutting cam and the second line cutting cam are fixed on a motor shaft of the line cutting driving motor, the first line cutting cam is connected with the movable knife through the first transmission mechanism, and the second line cutting cam is connected with the auxiliary knife through the second transmission mechanism; the outer peripheral surface of the first thread cutting cam is provided with a seam starting thread cutting driving section and a seam post thread cutting driving section;

When the sewing machine starts the seam, the starting seam cutting driving section acts on the first transmission mechanism;

When the sewing machine finishes sewing, the post-sewing thread cutting driving section acts on the first transmission mechanism.

The utility model also provides a sewing machine, wherein the sewing machine is provided with the bird nest less thread cutting and air suction mechanism.

As described above, the bird nest less thread cutting and air suction mechanism and the sewing machine have the following beneficial effects:

When the needle is used for starting the seam, firstly, a needle passes through the seam starting thread hooking groove, the thread hooking of the rotating shuttle is combined, the upper thread end is brought under the movable cutter, then, the needle is moved upwards out of the seam starting thread hooking groove, the upper thread end is pulled out of a part of the movable cutter, the upper thread end and the lower thread end are captured in advance through the air suction effect of the air suction opening, and finally, the thread end is cut by the seam starting thread cutting edge, so that the upper thread end is prevented from winding to form a bird nest. When the sewing is finished and the thread is cut, the upper thread and the bottom thread are cut by the cutting edge of the thread after sewing. Therefore, the application can reliably realize the automatic thread trimming with less bird nest for starting and finishing the sewing. In particular, after finishing sewing and trimming, the bottom thread head is caught again through the air suction effect of the air suction opening, and the air suction opening faces the rotating shuttle along the axial direction of the rotating shuttle and is lower than the upper end of the rotating shuttle, so that the bottom thread head is inclined downwards after finishing sewing and during starting, when starting, the bottom thread head inclined downwards is positioned on the path of the upper thread loop, when the upper thread loop passes through the upper thread loop, the bottom thread is wound more easily, the bottom thread is helped to be lifted in the starting stage of sewing, the probability that the bottom thread cannot be lifted by the lifting belt is reduced, and the normal formation of the lifting thread is reliably ensured.

Drawings

FIG. 1 is a schematic diagram of a line-shearing suction mechanism with less bird nest according to an embodiment of the present application.

Fig. 2a to 2f are schematic structural views of a plurality of embodiments of movable knives in a first embodiment of a bird nest thread cutting mechanism.

Fig. 3 is a schematic structural view of an auxiliary knife in a first embodiment of a bird nest thread cutting mechanism.

Fig. 4a to 4d are schematic diagrams illustrating a trimming process of a bird nest trimming mechanism according to a first embodiment.

Fig. 5 is a schematic diagram of connection between a first wire cutting drive source and a movable blade in a first embodiment of a bird's nest wire cutting mechanism.

FIG. 6 is a schematic drawing of a bird's nest thread cutting mechanism with thread suction at the suction opening after finishing thread cutting.

FIG. 7 is a diagram of a bird's nest thread cutting mechanism with a suction port for sucking thread during seam cutting.

Fig. 8 is a schematic structural diagram of a second embodiment of the bird nest less wire cutting and air suction mechanism of the present application, showing only the movable blade and the auxiliary blade.

Fig. 9a to 9d are schematic diagrams of a wire cutting process of a second embodiment of the wire cutting and suction mechanism with less bird nest.

FIG. 10 is a schematic diagram of a third embodiment of a low bird nest shear line suction mechanism.

FIG. 11 is a schematic diagram of a fourth embodiment of a low bird nest shear line suction mechanism.

Fig. 12 is a schematic structural diagram of a fifth embodiment of the bird nest less trimming suction mechanism of the present application.

Fig. 13 is a schematic structural view of a first thread cutting cam in a fifth embodiment of a bird's nest thread cutting mechanism.

Description of element reference numerals

10. Machine needle

20. Rotating shuttle

30. Auxiliary knife

31. Third wire clamping part

32. Auxiliary knife line cutting edge

33. Second lifting blade

40. Movable knife

41. Thread hooking groove for starting seam

42. Shared cutting edge

43. Wire dividing groove

44. Cutting wire and branching tip

45. Avoid needle groove

46. Edge bulge

47. Bump through hole

48. Transition surface

49. Line containing groove after sewing

410. Seam-lifting line-holding groove

411. First wire clamping part

412. First lifting blade

50. Sewing machine bottom plate

51. Guide chute

61. First thread cutting driving source

62. Wire cutting driving shaft

63. First thread cutting crank

64. First trimming connecting rod

65. Movable knife rest

70. Air suction pipe

71. Air suction port

81. Second wire cutting driving source

82. Second wire cutting crank

83. Second wire cutting connecting rod

84. First return spring

91. Wire cutting driving motor

92. First thread cutting cam

921. Thread cutting driving section for seam lifting

922. Post-sewing thread cutting driving section

93. Second thread cutting cam

94. First transmission shaft

95. First transmission crank

96. Second transmission crank

97. First roller

98. First transmission connecting rod

99. First tool rest

910. Second transmission shaft

911. Third transmission crank

912. Fourth transmission crank

913. Second roller

914. Second transmission connecting rod

915. Second tool rest

916. Second return spring

917. Third return spring

110. Bottom line thread end

Detailed Description

Further advantages and effects of the present utility model will become apparent to those skilled in the art from the disclosure of the present utility model, which is described by the following specific examples.

It should be understood that the structures, proportions, sizes, etc. shown in the drawings are for illustration purposes only and should not be construed as limiting the utility model to the extent that it can be practiced, since modifications, changes in the proportions, or adjustments of the sizes, which are otherwise, used in the practice of the utility model, are included in the spirit and scope of the utility model which is otherwise, without departing from the spirit or scope thereof. Also, the terms such as "upper", "lower", "left", "right", "middle", etc. are used herein for convenience of description, but are not to be construed as limiting the scope of the utility model, and the relative changes or modifications are not to be construed as essential to the scope of the utility model.

It will also be understood that when an element is referred to as being "mounted" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or be indirectly connected to the other element through intervening elements.

Furthermore, the description of "first," "second," etc. in this disclosure is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present application.

The utility model provides a sewing machine, which is provided with a thread cutting and air suction mechanism with less bird nests. In addition, as shown in fig. 1, the sewing machine is further equipped with a needle 10 reciprocally movable up and down, and a rotatable rotating shuttle 20. In the following embodiment, the axial direction of the rotary hook 20 is defined as the left-right direction, the extending direction of the needle 10 is defined as the up-down direction, the directions orthogonal to both the left-right direction and the up-down direction are defined as the front-back direction, and the front direction is the moving direction of the sewing material when the sewing machine is forward sewing. The following provides several embodiments of a bird nest less shear line suction mechanism.

Embodiment one of a line-shearing air suction mechanism with less bird nest

As shown in fig. 1, the first embodiment of the bird nest less thread cutting and air suction mechanism comprises an auxiliary knife 30, a movable knife 40 capable of moving towards or away from the auxiliary knife 30, and a fixedly arranged air suction pipe 70; the movable blade 40 and the auxiliary blade 30 are disposed inside and outside in the radial direction of the rotary hook 20, i.e., the movable blade 40 is disposed on the lower side of the auxiliary blade 30. As shown in fig. 2a or fig. 2b, the movable knife 40 is provided with a seam lifting and hooking groove 41, a seam lifting and hooking cutting edge and a seam post-cutting edge, the seam lifting and hooking groove 41 vertically penetrates the movable knife 40 along the thickness direction of the movable knife 40, the seam lifting and hooking groove 41 allows the needle 10 in the sewing machine to pass through, the seam lifting and hooking cutting edge and the seam post-cutting edge are the same common cutting edge 42, and the seam lifting and hooking groove 41 is distributed on one side of the common cutting edge 42 facing the auxiliary knife 30. As shown in fig. 3, the lower surface of the auxiliary knife 30 is provided with an auxiliary knife wire-cutting edge 32. By the movement of the movable knife 40, the stitch hooking groove 41 can be moved to the position right under the needle 10 in the sewing machine, or the common cutting edge 42 can be engaged with the auxiliary cutting edge 32 of the auxiliary knife 30. As shown in fig. 1, the suction duct 70 has a suction port 71, the suction port 71 being provided toward the rotating shuttle 20 in the axial direction of the rotating shuttle 20 in the sewing machine, i.e., the suction port 71 is provided on the left end side of the rotating shuttle 20, and the suction port 71 is also provided lower than the upper end of the rotating shuttle 20.

When the sewing machine starts the seam, firstly, the movable knife 40 moves to enable the seam starting and hooking groove 41 to move to the position right below the needle 10 in the sewing machine, and when the first needle 10 moves downwards during the seam starting of the sewing machine, the needle 10 passes through the seam starting and hooking groove 41 with the upper thread downwards, and under the action of the rotating shuttle 20, the upper thread head on one side of the needle 10 is brought to the position below the movable knife 40; meanwhile, the suction port 71 of the suction pipe 70 sucks air, picks up and pre-captures the upper thread end and the lower thread end 110, and after the lower thread end 110 is sucked into the suction port 71, the lower thread end 110 is inclined downward at the left side of the rotating shuttle 20 as the suction port 71 is lower than the upper end of the rotating shuttle 20, as shown in fig. 6; after the upper thread ends are sucked into the suction port 71, the upper thread ends which have been caught by the movable blade 40 are prevented from being wound again into the normal stitch to form a clew or caught in the guide rail of the rotating shuttle 20. Thereafter, the needle 10 is moved upward from the thread take-up groove 41 to withdraw a portion of the head of the upper thread. Then, the movable blade 40 moves in a direction approaching the auxiliary blade 30 until the common thread cutting edge 42 is engaged with the auxiliary blade 30 to cut the thread ends, thereby preventing the thread ends from being wound to form bird nests; the cut thread ends are automatically collected after passing through the suction duct 70.

At the end of sewing by the sewing machine, the movable knife 40 moves in a direction approaching the auxiliary knife 30, and in the process, the movable knife 40 moves together with the upper thread and the lower thread in a direction approaching the auxiliary knife 30 until the common cutting edge 42 can engage with the auxiliary knife 30 to cut the upper thread and the lower thread. Then, the suction port 71 of the suction pipe 70 sucks air, picks up and pre-captures the bottom thread end 110 on the rotating shuttle 20, and the bottom thread end 110 is inclined downwards at the left side of the rotating shuttle 20, as shown in fig. 6; in this way, in the next thread-lifting operation, the bobbin thread end 110 inclined downward on the left side of the rotating shuttle 20 is positioned on the path of the upper thread loop, which helps to lift the bobbin thread in the starting stage of sewing, and reduces the probability that the thread lifting tape does not lift the bobbin thread. At the same time, during the seam starting, the suction opening 71 of the suction pipe 70 sucks air, so that the bottom thread head 110 is inclined downwards at the left side of the rotating shuttle 20, the sucked direction of the bottom thread head 110 is consistent with the sucked direction after the sewing is finished and the thread is cut, and when the surface thread loop passes through the position, the bottom thread is easier to wind, as shown in fig. 7, so that the bottom thread of the seam starting belt is facilitated.

Therefore, the application can reliably realize the automatic thread trimming with less bird nest for starting and finishing the sewing. In particular, after finishing sewing and trimming, the bottom thread end 110 is caught again by the suction effect of the suction port 71, and the suction port 71 faces the rotating shuttle 20 along the axial direction of the rotating shuttle 20 and is lower than the upper end of the rotating shuttle 20, so that the bottom thread end 110 is inclined downwards after finishing sewing and during starting, the bottom thread end 110 inclined downwards is positioned on the path of the upper thread loop during starting, the bottom thread is wound more easily when the upper thread loop passes through the position, the bottom thread is helped to be lifted in the starting stage of sewing, the probability that the bottom thread cannot be lifted by the starting belt is reduced, and the normal formation of the starting thread is reliably ensured. In addition, the application sets the seam starting cutting edge and the seam finishing cutting edge as the same shared cutting edge 42, has simple structure, is easy to realize, does not need to additionally process the cutting edge on the existing movable knife, can reduce the change of the movable knife in the existing sewing machine, reduces the change cost and has strong universality.

Preferably, the first embodiment of the line-cutting air suction mechanism with less bird nest further comprises an air source, wherein the air source is arranged on the fixed frame, can be arranged on a bottom plate of the sewing machine, can be directly placed on the ground, is connected with one end of the air suction pipe 70, and the air suction inlet 71 is arranged at the other end of the air suction pipe 70. The air source is opened to provide continuous suction or intermittent suction both when the thread ends of the cut surface thread are lifted and when the sewing machine finishes cutting the surface thread and the bottom thread.

Further, as shown in fig. 6 and 7, the suction opening 71 is disposed near the release side of the upper thread loop on the rotating shuttle 20, i.e., in the front-rear direction, the suction opening 71 is near the front side of the rotating shuttle 20, which is more advantageous for winding the lower thread loop.

Further, the first embodiment of the bird nest less thread trimming suction mechanism is a single-acting knife structure, namely, the movable knife 40 is rotatably assembled below the sewing machine bottom plate 50, the rear end of the auxiliary knife 30 is fixed at the bottom of the sewing machine bottom plate 50 through a screw, and the movable knife 40 is moved back and forth to achieve that the movable knife 40 approaches or is far away from the auxiliary knife 30. In the initial state, the movable knife 40 and the auxiliary knife 30 are distributed on both sides of the needle 10, the movable knife 40 is distributed on the front side of the needle 10, and the auxiliary knife 30 is distributed on the rear side of the needle 10.

Further, as shown in fig. 5, the first embodiment of the bird nest less thread cutting suction mechanism further comprises a first thread cutting driving source 61, a thread cutting driving shaft 62 rotatably supported in the sewing machine base plate 50, a first thread cutting crank 63 fixed on the thread cutting driving shaft 62, a first thread cutting connecting rod 64, and a movable knife rest 65 rotatably supported in the sewing machine base plate 50, wherein the first thread cutting driving source 61 is a motor, preferably a stepping motor, and the first thread cutting driving source 61 is connected with the thread cutting driving shaft 62 to drive the thread cutting driving shaft 62 to rotate; two ends of the first wire cutting connecting rod 64 are respectively hinged with the first wire cutting crank 63 and the movable knife rest 65, and the right end part of the movable knife 40 is fixed on the movable knife rest 65 through a screw, so that two fixing holes are formed in the right end part of the movable knife 40. When the first wire cutting driving source 61 drives the wire cutting driving shaft 62 to rotate, the first wire cutting crank 63 rotates along with the wire cutting driving shaft 62, the movable knife holder 65 is driven to rotate back and forth through the first wire cutting connecting rod 64, and the movable knife 40 rotates back and forth along with the movable knife holder 65, so that the movable knife 40 is driven to rotate backward to be close to the auxiliary knife 30 or to rotate forward to be far away from the auxiliary knife 30.

Further, based on the auxiliary knife 30 being distributed at the rear side of the movable knife 40, the seam hooking groove 41 is distributed at the rear side of the common cutting edge 42. Preferably, the movable blade 40 is a circular arc blade body, and the extending track of the circular arc blade body is basically consistent with the rotating track of the movable blade 40. As shown in fig. 2a or 2b, the movable blade 40 is provided with a parting groove 43 and a parting tip 44, the common parting edge 42 and the parting tip 44 are respectively provided at the front side and the rear side of the movable blade 40, and the parting groove 43 is distributed between the common parting edge 42 and the parting tip 44. When the thread cutting is completed, the thread cutting tip 44 and the thread dividing groove 43 cooperate to separate the bobbin thread from the face thread.

Further, as shown in fig. 2a or 2b, the movable knife 40 is further provided with a needle avoiding slot 45, and the needle avoiding slot 45 allows the needle 10 in the sewing machine to pass through. When the sewing machine starts to stitch the second needle, the third needle and … to a set needle number, the avoidance needle passing groove 45 is positioned right below the sewing machine needle 10 through the rotation of the movable knife 40, the sewing machine needle 10 punctures up and down in the avoidance needle passing groove 45, and starts to stitch to set the needle number, and in the process, the shared cutting edge 42 is adjacent to the auxiliary knife 30 but is not meshed with the auxiliary knife 30. When the thread count is set, the thread ends are cut by the engagement of the common thread cutting edge 42 and the auxiliary knife 30. In addition, the seam lifting and hooking groove 41 and the avoidance needle passing groove 45 on the movable knife 40 are arranged in various ways, so that the movable knife 40 has a plurality of embodiments.

In the first embodiment of the movable blade 40, as shown in fig. 2a, the movable blade 40 is provided with a protruding cutting edge bulge 46 at the common cutting edge 42, a bulge through hole 47 penetrating up and down is formed in the cutting edge bulge 46, the bulge through hole 47 is in a circular hole structure, the front edge of the bulge through hole 47 forms the common cutting edge 42, and the bulge through hole 47 forms the seam-raising thread hooking groove 41. The avoidance needle passing groove 45 is a hollow region formed on the front edge side of the movable blade 40, and the avoidance needle passing groove 45 is provided adjacent to the suture hooking groove 41. Preferably, the outer edge of the movable knife 40 is provided with a transition surface 48 distributed between the avoidance needle slot 45 and the common shearing edge 42, the transition surface 48 is an inclined surface or an arc surface, and the transition surface 48 is in smooth transition connection with the outer edge of the peripheral movable knife 40. After the thread cutting is completed at the end of sewing, the movable knife 40 is rotated forward to reset, and in the process, the transition surface 48 slightly separates the bottom thread to prevent the bottom thread from being pulled. The avoidance needle passing groove 45, the common shearing cutting edge 42, the seam lifting and hooking groove 41 and the branching groove 43 are distributed on the same circumference line of the movable knife 40 along the circumference direction of the movable knife 40 and are sequentially distributed from front to back. In addition, a post-sewing thread accommodating groove 49 is formed on the upper surface of the movable knife 40, and the front and rear ends of the post-sewing thread accommodating groove 49 are respectively connected between the common thread cutting edge 42 and the thread dividing groove 43, wherein the post-sewing thread accommodating groove 49 is used for accommodating upper threads and lower threads when thread cutting is finished during sewing.

In the second embodiment of the movable knife 40, as shown in fig. 2b, the suture hooking groove 41 is located away from the common cutting edge 42, the common cutting edge 42 is close to the front side of the movable knife 40, the suture hooking groove 41 is close to the rear side of the movable knife 40, and the thread dividing grooves 43 are distributed between the common cutting edge 42 and the suture hooking groove 41. The movable blade 40 has a protruding edge bulge 46 at the common cutting edge 42, a bulge through hole 47 penetrating up and down is provided in the edge bulge 46, and the front edge of the bulge through hole 47 constitutes the common cutting edge 42. The needle passing avoidance groove 45 is a hollow region formed on the front edge side of the movable blade 40. Preferably, the upper surface of the movable knife 40 is provided with a seam-lifting line-containing groove 410 and a seam-rear line-containing groove 49, the front and rear ends of the seam-lifting line-containing groove 410 are connected between the common cutting edge 42 and the seam-lifting line-hooking groove 41, and the front and rear ends of the seam-rear line-containing groove 49 are respectively connected between the common cutting edge 42 and the line-distributing groove 43. The common cutting edge 42, the branching groove 43 and the seam lifting hook groove 41 are arranged from front to back in sequence, so that the seam rear containing groove 49 is a part of the seam lifting containing groove 410. In the second embodiment of the movable cutter 40, since the seam lifting hook slot 41 is disposed away from the common cutting edge 42, more upper thread ends can be drawn out to the upper surface of the movable cutter 40 during the seam lifting and cutting process, and the upper thread ends are accommodated in the seam lifting and holding slot 410.

The third embodiment of the movable blade 40 differs from the first embodiment of the movable blade 40 only in that: as shown in fig. 2c, the seam-raising and hooking grooves 41 are distributed between the bulge through holes 47 and the branching grooves 43, the seam-raising and hooking grooves 41 are arranged adjacent to the bulge through holes 47, and the seam-raising and hooking grooves 41 are through grooves penetrating up and down and are of a closed groove structure. The sewing thread hooking groove 41 is not communicated with the bulge through hole 47, and the sewing thread hooking groove 41 is a waist-shaped hole extending forwards and backwards.

The fourth embodiment of the movable blade 40 differs from the third embodiment of the movable blade 40 only in that: as shown in fig. 2d, the front end of the sewing thread groove 41 extends forward to the rear end of the bulge through hole 47, that is, the sewing thread groove 41 communicates with the bulge through hole 47, and the two are combined into an integral structure.

The fifth embodiment of the movable blade 40 differs from the third embodiment of the movable blade 40 only in that: as shown in fig. 2e, the seam lifting hook groove 41 is an open groove structure with an opening at the left side, and the left end of the seam lifting hook groove 41 extends to the left edge of the movable knife 40.

The sixth embodiment of the movable blade 40 differs from the third embodiment of the movable blade 40 only in that: as shown in fig. 2f, the seam hooking groove 41 is a circular hole.

Further, in the above six embodiments of the movable blade 40, the right end side of the rear edge of the movable blade 40 is integrally provided with a first blade lifting wing 412 extending backward for lifting the auxiliary blade 30 so that the movable blade 40 can be better engaged with the auxiliary blade 30. Of course, the movable blade 40 may not be provided with the first lift wing 412, as long as the movable blade 40 and the auxiliary blade 30 are well engaged. Preferably, the side of the auxiliary blade 30 is integrally provided with a second lift wing 33 for abutting the movable blade 40, so that the movable blade 40 can be better engaged with the auxiliary blade 30. Of course, the second lifting wing 33 may not be provided on the auxiliary blade 30 in order to ensure that the movable blade 40 is well engaged with the auxiliary blade 30.

Further, in the embodiment of the thread cutting and air suction mechanism with less bird nest, the upper thread end is in a clamped state in the process of starting the second needle to the set needle number before cutting the upper thread end, so that the upper thread end is prevented from being separated. The clamping of the upper thread ends is preferably carried out in two ways.

Mode one, the upper thread end is clamped by the movable knife 40 and the additionally arranged thread pressing plate. Based on the above, the first embodiment of the bird nest less thread cutting and air suction mechanism also comprises a thread pressing plate which is fixedly arranged; the thread pressing plate, the auxiliary knife 30 and the movable knife 40 are sequentially distributed from outside to inside along the radial direction of the rotating shuttle 20; the upper surface of the movable knife 40 is provided with a first wire clamping part 411, and the wire pressing plate is provided with a second wire clamping part. When the movable knife 40 moves to make the avoidance needle passing groove 45 be located right below the needle 10, a thread clamping slit for clamping the thread end of the upper thread is formed between the first thread clamping part 411 and the second thread clamping part. Preferably, the thread pressing plate may be fixed to the auxiliary knife 30 or may be directly fixed to the bottom of the sewing machine bed 50.

In the second mode, the movable knife 40 and the auxiliary knife 30 clamp the upper thread end. Based on this, as shown in fig. 3 and 4c, the upper surface of the movable blade 40 is provided with a first thread clamping portion 411, the lower surface of the auxiliary blade 30 is provided with a third thread clamping portion 31, and the auxiliary blade cutting edges 32 of the auxiliary blade 30 are distributed at the rear side of the third thread clamping portion 31. When the movable knife 40 moves to make the avoidance needle passing groove 45 be located right below the needle 10, a thread clamping slit for clamping the thread end of the upper thread is formed between the first thread clamping part 411 and the third thread clamping part 31.

The working principle of the first embodiment of the low bird nest thread cutting suction mechanism will be described by taking the example that the first embodiment of the low bird nest thread cutting suction mechanism is provided with the movable knife 40, the movable knife 40 cooperates with the auxiliary knife 30 to clamp the upper thread end, and the suction opening 71 is provided at the left end side of the rotating shuttle 20.

1.1, Before or while the first needle is being sewn, the movable knife 40 is rotated backwards, so that the sewing hooking groove 41 is located right below the needle 10; after that, when the first needle 10 for starting the seam moves downward, the needle 10 passes through the thread hooking groove 41 with the upper thread downward, as shown in fig. 4a, and the upper thread end on one side of the needle 10 is brought under the movable knife 40, that is, brought to the vicinity of the rotating shuttle 20, under the hooking action of the rotating shuttle 20. In this process, the electronic thread clamp on the sewing machine can be opened to more reliably bring the upper thread end on one side of the needle 10 to the lower side of the movable knife 40. At the same time, the air source is turned on, and the air suction port 71 of the air suction device sucks the upper thread end and the lower thread end 110 as shown in fig. 4 b; in particular, the suction means supplies suction power at a time point not later than the time point at which the upper thread is carried to the bobbin case after the thread is hooked by the rotating shuttle 20.

1.2, The needle 10 starts the first needle 10 to move upwards, after the standby needle 10 moves upwards out of the starting thread hooking groove 41, the movable knife 40 rotates backwards towards the direction close to the auxiliary knife 30, as shown in fig. 4c, until the first thread clamping part 411 of the movable knife 40 just contacts with the third thread clamping part 31 of the auxiliary knife 30, the two parts press and clamp the upper thread end, and meanwhile, the avoidance thread passing groove 45 of the movable knife 40 is positioned under the needle 10.

1.3, The sewing machine continues to stitch the second needle and the third needle, and cuts the thread end of the thread in the process that the set stitch N needle forms the thread loop, wherein N is more than or equal to 2. Such as: cutting off thread ends in the process of forming a thread loop by the second needle after the seam is lifted, moving the second needle 10 downwards, and puncturing the needle 10 from the avoidance needle passing groove 45 without interfering with the movable knife 40; then the rotating shuttle 20 hooks the thread to form the upper thread loop, when the upper thread loop expands to the maximum, the upper thread loop passes through the lowest part of the shuttle shell of the rotating shuttle 20, and the upper thread loop contacts with the upper thread end sucked by the suction inlet 71; then the thread take-up lever starts to take up the thread, the lower upper thread loop gradually contracts, and the upper thread is gradually lifted out of the track of the rotating shuttle 20. When the take-up lever is lifted back to the target position a of the non-highest point thereof, the movable blade 40 continues to be rotated backward in a direction approaching the auxiliary blade 30 as shown in fig. 4d until the common cutting edge 42 is engaged with the auxiliary blade 30 to cut the thread ends, thereby preventing the winding of the thread ends to form a bird nest, and the cut thread ends are sucked by the suction ports 71. Then, the thread take-up lever continues to lift, the upper thread cut below the sewing material is pulled back, the bottom thread is also tightened together, and the length of the bird nest is further reduced through the upper thread pulling back. The thread ends are cut in the process of forming the thread loops by the needle which is in the seam, and the thread ends are adjusted according to the realization effect.

1.4, After the seam lifting and trimming is completed, the movable knife 40 rotates forwards in the direction away from the auxiliary knife 30 until reset; in the process, the bottom line passes through the transition surface 48 of the movable knife 40, so that the position and the line tension of the bottom line are not affected; the air supply is shut off and suction inlet 71 ceases to suck air.

1.5, The sewing machine performs normal sewing.

1.6, When the sewing is finished and the thread needs to be cut, the movable knife 40 rotates backwards, and the thread cutting tip 44 passes through the upper thread loop; as the movable blade 40 continues to rotate backward, the base thread and the upper thread cut on one side slide into the thread-separating groove 43, and thereafter, the base thread and the upper thread are accommodated in the post-sewing thread-accommodating groove 49; when the common shearing edge 42 is engaged with the auxiliary knife 30, the upper and lower threads are sheared. Thereafter, the movable blade 40 is rotated forward until reset.

1.7, The air source is turned on, the suction opening 71 of the suction device sucks the bobbin thread end 110, and the bobbin thread end 110 is inclined to the left and the lower as shown in fig. 6. In this way, the bottom thread end 110 inclined to the left and down is positioned on the path of the upper thread loop in the next sewing start stage, which is helpful for carrying the bottom thread and reducing the probability of the bottom thread being not carried by the sewing belt. In addition, when the seam is lifted, the air source is also in an open state, the bottom thread end 110 is easy to suck, the direction in which the bottom thread end 110 is sucked when the seam is lifted is consistent with the direction in which the bottom thread end 110 is sucked after the seam is cut, and when the surface thread loop passes through the position, the bottom thread is necessarily easier to wind, as shown in fig. 7, so that the seam lifting belt bottom thread is facilitated.

In a comprehensive way, the embodiment of the air suction mechanism with fewer bird nests and thread cutting has a simple structure, so that the length of the bird nest can be reduced, and the sewing quality can be improved; the structure is simple, the cost is low, the durability is strong, and the sewing space is not occupied; the universality is strong, and the structure is well suitable for the existing line shearing structure in the market, so that the effect of less bird nest can be realized after the structure is modified; meanwhile, the probability that the seam tape cannot be lifted up can be greatly reduced.

Embodiment II of line-shearing air suction mechanism with less bird nest

The second embodiment of the wire-cutting and air-suction mechanism with less bird nests differs from the first embodiment of the wire-cutting and air-suction mechanism with less bird nests only in that: as shown in fig. 8, in the initial state, the movable blade 40 and the auxiliary blade 30 are disposed on the same side of the needle 10, in this embodiment, the rear side, and the movable blade 40 and the auxiliary blade 30 are in the engaged state. Therefore, the working principle of the second embodiment of the bird nest less thread cutting suction mechanism is described as follows.

2.1, Before or while the first needle is being stitched, the movable knife 40 is rotated forward, as shown in fig. 9a, so that the stitch-lifting hook slot 41 is located directly under the needle 10; after that, when the first needle 10 for starting the seam moves downward, the needle 10 passes through the starting seam hooking groove 41 with the upper thread downward, and the upper thread end on one side of the needle 10 is brought to the vicinity of the rotating shuttle 20 under the hooking action of the rotating shuttle 20. At the same time, the air source is turned on, and the suction port 71 of the suction means sucks the upper thread end and the lower thread end 110.

2.2, The needle 10 starts the first needle 10 to move upwards, after the standby needle 10 moves upwards out of the starting thread hooking groove 41, the movable knife 40 rotates backwards towards the direction close to the auxiliary knife 30, as shown in fig. 9b, until the first thread clamping part 411 of the movable knife 40 just contacts with the third thread clamping part 31 of the auxiliary knife 30, the two parts press and clamp the upper thread end, and meanwhile, the avoidance thread passing groove 45 of the movable knife 40 is located under the needle 10. In addition, the time point when the movable knife 40 rotates backwards towards the auxiliary knife 30 is not later than the time point when the second needle-lifting needle 10 moves downwards to the position, so as to ensure that the second needle-lifting needle 10 can puncture in the avoidance needle passing groove 45.

2.3, Continuously starting the second needle and the third needle by the sewing machine, and shearing the thread end of the thread in the process that the set starting Nth needle forms a thread loop, wherein N is more than or equal to 2; the specific process is the same as step 1.3 in the first embodiment of the bird nest cutting and air suction mechanism.

2.4, After the seam lifting and trimming is completed, the movable knife 40 is at the initial position; at the same time, the air supply is shut off and suction port 71 stops sucking air.

And 2.5, the sewing machine performs normal sewing.

2.6 Before the thread is cut after the end of sewing and when the needle 10 is above the needle plate of the sewing machine, the movable knife 40 is rotated forward in a direction away from the auxiliary knife 30, and as shown in fig. 9c, the movable knife 40 is rotated to the front side of the needle 10 to wait for the thread cutting operation after sewing. After that, when the sewing is completed and the thread needs to be cut, the movable knife 40 rotates backwards towards the direction approaching to the auxiliary knife 30, firstly the thread cutting and branching tip 44 passes through the upper thread loop, then the bottom thread and the upper thread on the cut side slide into the branching groove 43 and are accommodated in the post-sewing accommodating groove 49; when the common cutting edge 42 is engaged with the auxiliary knife 30, the upper and lower lines are cut as shown in fig. 9 d. After the post-stitch thread cutting is completed, the movable blade 40 is at its initial position, and the movable blade 40 does not need to be reset and is kept at that position.

2.7, The air source is started, and the air suction opening 71 of the air suction device sucks the bottom line head 110, so that the bottom line head 110 is inclined to the left and the lower.

Embodiment III of line-shearing air suction mechanism with less bird nest

The third embodiment of the wire-cutting air suction mechanism with fewer bird nests differs from the first embodiment of the wire-cutting air suction mechanism with fewer bird nests only in that: the auxiliary knife 30 is movably assembled back and forth under the sewing machine bed 50. Based on this, as shown in fig. 10, the bird nest less thread cutting and air suction mechanism further includes a second thread cutting driving source 81, and the second thread cutting driving source 81 is in transmission connection with the auxiliary blade 30 to drive the auxiliary blade 30 to translate back and forth.

Further, the second thread cutting driving source 81 is a motor, preferably a stepping motor, and the second thread cutting driving source 81 is fixed on the bottom surface of the sewing machine bottom plate 50, and the second thread cutting driving source 81 is connected with the rear end of the auxiliary knife 30 through a driving transmission mechanism. In the embodiment, the driving transmission mechanism adopts a crank-link mechanism; based on this, as shown in fig. 10, the third embodiment of the bird nest less thread cutting suction mechanism further includes a second thread cutting crank 82 fixed on the motor shaft of the second thread cutting driving source 81, and a second thread cutting link 83, both ends of the second thread cutting link 83 being hinged with the second thread cutting crank 82 and the auxiliary blade 30, respectively, and the second thread cutting driving source 81 driving the auxiliary blade 30 to move forward or backward through the second thread cutting crank 82 and the second thread cutting link 83. In other embodiments, the second thread cutting driving source 81 and the auxiliary knife 30 may be connected by a gear mechanism or a synchronous pulley mechanism, and the second thread cutting driving source 81 may be fixed on a casing of the sewing machine, a platen, or an oil pan.

Preferably, as shown in fig. 10, a guide chute 51 extending straight back and forth is provided at the bottom of the sewing machine bottom plate 50, and the auxiliary knife 30 is movably fitted in the guide chute 51, and the stability of the forward and backward movement of the auxiliary knife 30 is improved by the sliding guide engagement of the two.

The working principle of the third embodiment of the bird nest less thread cutting air suction mechanism is described as follows.

3.1, Before or while the first needle is being sewn, the movable knife 40 is rotated backwards, so that the sewing hooking groove 41 is positioned right below the needle 10; after that, when the first needle 10 for starting the seam moves downward, the needle 10 passes through the starting seam hooking groove 41 with the upper thread downward, and the upper thread end on one side of the needle 10 is brought to the vicinity of the rotating shuttle 20 under the hooking action of the rotating shuttle 20. At the same time, the air source is turned on, and the suction port 71 of the suction means sucks the upper thread end and the lower thread end 110.

3.2, The first needle 10 for starting the seam of the needle 10 moves upwards, after the standby needle 10 moves upwards from the seam hooking groove 41, the movable knife 40 rotates backwards towards the direction close to the auxiliary knife 30, the auxiliary knife 30 can be kept still, and can also translate forwards until the first thread clamping part 411 of the movable knife 40 just contacts with the third thread clamping part 31 of the auxiliary knife 30, so that the effect of clamping the upper thread ends is achieved; meanwhile, the avoidance needle passing groove 45 of the movable knife 40 is positioned right below the needle 10.

3.3, Continuously starting the second needle and the third needle by the sewing machine, and shearing the thread end of the thread in the process that the set starting Nth needle forms a thread loop, wherein N is more than or equal to 2; the specific process is the same as step 1.3 in the first embodiment of the bird nest cutting and air suction mechanism. In this embodiment, however, the movable blade 40 remains stationary while the line ends are cut, and the auxiliary blade 30 translates forward; or the movable blade 40 rotates backward, and the auxiliary blade 30 remains stationary; or the movable blade 40 rotates backward and the auxiliary blade 30 translates forward to achieve the effect that the common shearing edge 42 engages the auxiliary blade 30 with the shearing line head.

3.4, After the seam lifting and trimming are completed, the movable knife 40 and the auxiliary knife 30 are reset respectively; the air supply is shut off and suction inlet 71 ceases to suck air.

And 3.5, the sewing machine performs normal sewing.

3.6, When the sewing is finished and the thread needs to be cut, the movable knife 40 rotates backwards, and the thread cutting tip 44 passes through the upper thread loop; as the movable blade 40 continues to rotate backward, the base thread and the upper thread cut on one side slide into the thread-separating groove 43, and thereafter, the base thread and the upper thread are accommodated in the post-sewing thread-accommodating groove 49; the auxiliary knife 30 can be kept still or can be translated forward until the common cutting edge 42 engages the auxiliary knife 30, thereby ultimately achieving the effect of cutting the upper and lower threads. Thereafter, the movable blade 40 and the auxiliary blade 30 are each reset.

3.7, The air source is started, and the air suction opening 71 of the air suction device sucks the bottom line head 110, so that the bottom line head 110 is inclined to the left and the lower.

Fourth embodiment of line-shearing air suction mechanism with less bird nest

The fourth embodiment of the line-cutting air suction mechanism with fewer bird nests differs from the third embodiment of the line-cutting air suction mechanism with fewer bird nests only in that: the type of the second wire cutting driving source 81 and the connection structure between the second wire cutting driving source 81 and the auxiliary knife 30 are different. Specifically, in the fourth embodiment of the bird nest less thread cutting suction mechanism, as shown in fig. 11, the second thread cutting driving source 81 is a cylinder or an electromagnet, and the cylinder or the electromagnet is fixed on the bottom surface of the sewing machine bottom plate 50; the rear end of the auxiliary knife 30 is directly arranged at the end part of a piston rod of the air cylinder or the end part of an iron core of the electromagnet, and the air cylinder or the electromagnet directly drives the auxiliary knife 30 to move forwards or backwards, so that a driving transmission mechanism is not required to be directly arranged between the second wire cutting driving source 81 and the auxiliary knife 30.

In addition, when the second wire cutting driving source 81 is an electromagnet, as shown in fig. 11, a first return spring 84 is sleeved on the iron core of the electromagnet, and two ends of the return spring are respectively abutted against the shell and the iron core of the electromagnet for resetting the iron core.

The working principle of the fourth embodiment of the wire-cutting and air-suction mechanism with less bird nest is the same as that of the third embodiment of the wire-cutting and air-suction mechanism with less bird nest, and the description thereof will not be repeated here.

Embodiment five of line-shearing air suction mechanism with less bird nest

The fifth embodiment of the wire-cutting air suction mechanism with fewer bird nests differs from the first embodiment of the wire-cutting air suction mechanism with fewer bird nests only in that: the movable knife 40 and the auxiliary knife 30 are rotatably mounted under the sewing machine bed 50. Based on this, as shown in fig. 12, the embodiment five of the bird nest less wire cutting and suction mechanism further includes a wire cutting driving motor 91, a first wire cutting cam 92, a second wire cutting cam 93, a first transmission mechanism, and a second transmission mechanism; the thread cutting driving motor 91 is fixed on the bottom plate of the sewing machine, or on the casing, or on the oil pan; the first wire cutting cam 92 and the second wire cutting cam 93 are both fixed on the motor shaft of the wire cutting driving motor 91, and the first wire cutting cam 92 and the second wire cutting cam 93 can be two separated cam components or can be combined into the same cam component; the first wire cutting cam 92 is connected to the movable blade 40 via a first transmission mechanism, and the second wire cutting cam 93 is connected to the auxiliary blade 30 via a second transmission mechanism.

As shown in fig. 13, the outer peripheral surface of the first thread cutting cam 92 is provided with a starting thread cutting driving section 921 and a post-sewing thread cutting driving section 922; when the sewing machine starts the seam, the starting seam thread cutting driving section 921 acts on the first transmission mechanism and is used for starting seam less bird nest thread cutting control; at the end of the sewing machine, the post-sewing thread cutting drive section 922 acts on the first transmission mechanism for normal thread cutting control at the end of the sewing. In addition, when the stitch-starting thread-cutting driving section 921 of the first thread-cutting cam 92 acts on the first transmission mechanism, no power is transmitted between the second thread-cutting cam 93 and the second transmission mechanism; when the post-stitch wire cutting drive section 922 of the first wire cutting cam 92 acts on the first transmission mechanism, power is transferred between the second wire cutting cam 93 and the second transmission mechanism.

Further, as shown in fig. 12, the first transmission mechanism includes a first transmission shaft 94 rotatably supported in the sewing machine base plate 50, a first transmission crank 95 and a second transmission crank 96 respectively fixed to both ends of the first transmission shaft 94, a first roller 97 rotatably mounted to an outer end of the first transmission crank 95, a first transmission link 98, and a first cutter frame 99, the first roller 97 being in abutting engagement with an outer peripheral surface of the first thread cutting cam 92, both ends of the first transmission link 98 being hinged to the second transmission crank 96 and the first cutter frame 99 respectively, and the movable cutter 40 being fixed to the first cutter frame 99.

Further, as shown in fig. 12, the second transmission mechanism includes a second transmission shaft 910 rotatably supported in the sewing machine base plate 50, a third transmission crank 911 and a fourth transmission crank 912 respectively fixed to both ends of the second transmission shaft 910, a second roller 913 rotatably mounted on an outer end of the second transmission crank 96, a second transmission link 914, and a second blade holder 915, the second roller 913 being in abutting engagement with an outer peripheral surface of the second thread cutting cam 93, both ends of the second transmission link 914 being hinged to the fourth transmission crank 912 and the second blade holder 915 respectively, the auxiliary blade 30 being fixed to the second blade holder 915.

Preferably, the first drive mechanism further includes a second return spring 916, the second return spring 916 being sleeved on the first drive shaft 94, one end of the second return spring 916 being secured, and the other end acting on the second drive crank 96 for return of the movable blade 40. The second transmission mechanism further comprises a third return spring 917, the third return spring 917 is sleeved on the second transmission shaft 910, one end of the third return spring 917 is fixed, and the other end acts on the fourth transmission crank 912 for assisting the return of the knife 30.

The working principle of the fifth embodiment of the bird nest less line cutting and air suction mechanism is described as follows.

4.1, Before or at the same time of starting the first needle, the thread cutting driving motor 91 drives the first thread cutting cam 92 and the second thread cutting cam 93 to rotate, the starting thread cutting driving section 921 of the first thread cutting cam 92 is in contact fit with the first roller 97, and the movable knife 40 is driven to rotate backwards through the first transmission mechanism, so that the starting thread hooking groove 41 is positioned under the needle 10; and the second wire cutting cam 93 is separated from the second roller 913, or the constant diameter surface of the outer circumference of the second wire cutting cam 93 is contacted and matched with the second roller 913, the second transmission mechanism is not operated, and the auxiliary knife 30 is kept still. After that, when the first needle 10 for starting the seam moves downward, the needle 10 passes through the starting seam hooking groove 41 with the upper thread downward, and the upper thread end on one side of the needle 10 is brought to the vicinity of the rotating shuttle 20 under the hooking action of the rotating shuttle 20. At the same time, the air source is turned on, and the suction port 71 of the suction means sucks the upper thread end and the lower thread end 110.

4.2, The needle 10 starts the first needle 10 to move upwards, after the standby needle 10 moves upwards from the starting thread hooking groove 41, the thread cutting driving motor 91 continues to drive the first thread cutting cam 92 and the second thread cutting cam 93 to rotate, the starting thread cutting driving section 921 of the first thread cutting cam 92 continues to push the first roller 97 to drive the movable knife 40 to continue to rotate backwards, and the auxiliary knife 30 still keeps still until the first thread clamping part 411 of the movable knife 40 just contacts with the third thread clamping part 31 of the auxiliary knife 30, so as to achieve the effect of clamping the upper thread head; meanwhile, the avoidance needle passing groove 45 of the movable knife 40 is positioned right below the needle 10.

4.3, Continuously starting the second needle and the third needle by the sewing machine, and shearing the thread end of the thread in the process that the set starting Nth needle forms a thread loop, wherein N is more than or equal to 2; the specific process is the same as step 1.3 in the first embodiment of the bird nest cutting and air suction mechanism. But the movable blade 40 continues to rotate backward while cutting the line head, and the auxiliary blade 30 remains stationary.

4.4, Resetting the movable knife 40 after the seam lifting and trimming are completed; the air supply is shut off and suction inlet 71 ceases to suck air.

And 4.5, the sewing machine performs normal sewing.

4.6, When the sewing is finished and the thread needs to be cut, the thread cutting driving motor 91 drives the first thread cutting cam 92 and the second thread cutting cam 93 to rotate, the post-sewing thread cutting driving section 922 of the first thread cutting cam 92 is in contact fit with the first roller 97, and the movable knife 40 is driven to rotate backwards through the first transmission mechanism; simultaneously, the reducing section of the second wire cutting cam 93 is in contact fit with the second roller 913, and the auxiliary knife 30 is driven to rotate forwards through the second transmission mechanism; with the backward rotation of the movable knife 40, the thread cutting and branching tip 44 passes through the upper thread loop, then the lower thread and upper thread cut on one side slide into the branching groove 43 and are accommodated in the post-sewing accommodating groove 49, and finally the common thread cutting edge 42 engages with the auxiliary knife 30 to cut the upper thread and lower thread. Thereafter, the movable blade 40 and the auxiliary blade 30 are each reset.

4.7, The air source is started, and the air suction opening 71 of the air suction device sucks the bottom line head 110, so that the bottom line head 110 is inclined to the left and the lower.

In summary, the present utility model effectively overcomes the disadvantages of the prior art and has high industrial utility value.

The above embodiments are merely illustrative of the principles of the present utility model and its effectiveness, and are not intended to limit the utility model. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the utility model. Accordingly, it is intended that all equivalent modifications and variations of the utility model be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (10)

1. The utility model provides a little bird's nest trimming mechanism that induced drafts, includes auxiliary knife (30), can be to being close to or keep away from movable knife (40) of auxiliary knife (30) direction motion, its characterized in that: the automatic sewing machine further comprises an air suction pipe (70) which is fixedly arranged, a seam lifting cutting edge, a seam post-cutting edge and a seam lifting hooking groove (41) which allows a needle (10) in the sewing machine to pass through are arranged on the movable knife (40), the air suction pipe (70) is provided with an air suction opening (71), the air suction opening (71) is arranged along the axial direction of a rotating shuttle (20) in the sewing machine and faces the rotating shuttle (20), and the air suction opening (71) is also arranged lower than the upper end of the rotating shuttle (20);

When the sewing machine starts to sew, the air suction opening (71) is used for picking up the upper thread end and the lower thread end (110) and enabling the lower thread end (110) to incline downwards, and the thread cutting edge of the starting sewing machine can be meshed with the auxiliary knife (30) to cut the thread end of the thread;

At the end of sewing by the sewing machine, the cutting edge of the shearing line after sewing can be meshed with the auxiliary knife (30) to cut the surface line and the bottom line, and the air suction opening (71) is used for picking up the bottom line head (110) and enabling the bottom line head (110) to incline downwards.

2. The low bird nest wire cutting suction mechanism of claim 1, wherein: the air suction opening (71) is arranged near the release side of the upper thread loop on the rotating shuttle (20).

3. The low bird nest wire cutting suction mechanism of claim 1, wherein: the movable knife (40) is also provided with an avoidance needle passing groove (45), and the avoidance needle passing groove (45) allows a needle (10) in the sewing machine to pass through;

When the movable knife (40) moves to enable the avoidance needle passing groove (45) to be located right below the needle (10), the stitching and cutting edge is close to the auxiliary knife (30) but is not meshed with the auxiliary knife.

4. A bird nest less shear line suction mechanism as claimed in claim 3, wherein: the wire pressing device further comprises a wire pressing plate which is fixedly arranged, a first wire clamping part (411) is arranged on the surface of the movable knife (40), and a second wire clamping part is arranged on the wire pressing plate;

When the movable knife (40) moves to enable the avoidance needle passing groove (45) to be located right below the needle (10), a thread clamping seam for clamping the thread end of the upper thread is formed between the first thread clamping portion (411) and the second thread clamping portion.

5. A bird nest less shear line suction mechanism as claimed in claim 3, wherein: the surface of the movable knife (40) is provided with a first wire clamping part (411), and the auxiliary knife (30) is provided with a third wire clamping part (31);

When the movable knife (40) moves to enable the avoidance needle passing groove (45) to be located right below the needle (10), a thread clamping seam for clamping the thread end of the upper thread is formed between the first thread clamping portion (411) and the third thread clamping portion (31).

6. The low bird nest wire cutting suction mechanism of claim 1, wherein: the movable knife (40) is rotatably assembled below the sewing machine bottom plate (50), and the auxiliary knife (30) is fixed at the bottom of the sewing machine bottom plate (50).

7. The low bird nest wire cutting suction mechanism of claim 1, wherein: the movable knife (40) is rotatably mounted below the sewing machine base plate (50), and the auxiliary knife (30) is movably mounted below the sewing machine base plate (50).

8. The low bird nest wire cutting suction mechanism of claim 1, wherein: the movable knife (40) and the auxiliary knife (30) are rotatably assembled below a sewing machine base plate (50).

9. The low bird nest wire cutting suction mechanism of claim 8, wherein: the wire cutting machine further comprises a wire cutting driving motor (91), a first wire cutting cam (92), a second wire cutting cam (93), a first transmission mechanism and a second transmission mechanism, wherein the first wire cutting cam (92) and the second wire cutting cam (93) are both fixed on a motor shaft of the wire cutting driving motor (91), the first wire cutting cam (92) is connected with the movable knife (40) through the first transmission mechanism, and the second wire cutting cam (93) is connected with the auxiliary knife (30) through the second transmission mechanism; the outer peripheral surface of the first thread cutting cam (92) is provided with a seam starting thread cutting driving section (921) and a seam post thread cutting driving section (922);

When the sewing machine starts the seam, the starting seam thread cutting driving section (921) acts on the first transmission mechanism;

at the end of the sewing machine, the post-sewing thread cutting drive section (922) acts on the first transmission mechanism.

10. A sewing machine, characterized in that: the sewing machine is equipped with the bird nest less thread cutting suction mechanism as claimed in any one of claims 1 to 9.