CN221167026U - Little bird nest thread trimming mechanism and sewing machine - Google Patents

Abstract

The utility model provides a nest-less thread cutting mechanism and a sewing machine, comprising an auxiliary knife and a movable knife, wherein the movable knife is provided with a thread cutting edge, a through cutting edge through hole, a seam lifting hook slot, a seam lifting thread cutting edge and a post-seam thread cutting edge are arranged at the thread cutting edge, the seam lifting hook slot is a cutting edge through hole and allows a needle in the sewing machine to pass through, the seam lifting thread cutting edge and the post-seam thread cutting edge are both thread cutting edges, and the thread cutting edges form a common thread cutting edge; when the sewing machine starts to sew, the shared thread cutting edge can be meshed with the auxiliary knife to cut the thread head of the thread, thereby preventing the thread head of the thread from winding to form a bird nest; when the sewing machine finishes sewing, the shared cutting edge can be meshed with the auxiliary knife to cut the upper thread and the bottom thread. The utility model sets the seam lifting cutting edge and the seam post cutting edge as the same shared cutting edge, adopts the existing cutting edge through hole as the seam lifting hook slot, has simple structure and easy realization, can reduce the change of the existing movable knife and reduce the change cost.

Description

Little bird nest thread trimming mechanism and sewing machine

Technical Field

The utility model relates to the technical field of sewing machines, in particular to a small bird nest thread cutting mechanism 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.

The second mode adopts the little bird nest thread cutting device for cut the section line head when playing the seam, but current little bird nest thread cutting device very easily appears the phenomenon that the face line breaks away from after playing the seam and cuts the line, causes follow-up can not form good stitch, reduces sewing quality. In addition, the device for cutting the thread with less bird nest is also used for automatically cutting the thread at the end of sewing, so that two cutting edges are needed on the movable cutter for cutting the thread, and the movable cutter is respectively used for starting to cut the thread and cutting the thread at the end of sewing, such as a sewing machine movable cutter structure and a thread cutting device thereof disclosed in China patent application number 202222738011.2, and the structure is complex.

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 thread trimming mechanism, which has a simple structure and can reliably implement small bird nest for seam starting and automatic thread trimming at the end of sewing.

In order to achieve the above purpose, the utility model provides a nest-less thread cutting mechanism, which comprises an auxiliary knife and a movable knife capable of moving towards or away from the auxiliary knife, wherein the movable knife is provided with a thread cutting edge, a through-cutting edge through hole is formed at the thread cutting edge, the movable knife is provided with a seam-lifting thread hooking groove, a seam-lifting thread cutting edge and a seam-rear thread cutting edge, the seam-lifting thread hooking groove is the cutting edge through hole and allows a needle in a sewing machine to pass through, the seam-lifting thread cutting edge and the seam-rear thread cutting edge are both the thread cutting edges, and the thread cutting edges form a common thread cutting edge;

When the sewing machine starts to sew, the shared cutting edge can be meshed with the auxiliary knife to cut the thread ends of the thread;

When the sewing machine finishes sewing, the shared cutting edge can be meshed with the auxiliary knife to cut the upper thread and the lower thread.

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 common cutting edge is close to the auxiliary knife but is not meshed with the auxiliary knife.

Further, the avoidance needle passing groove is a hollow area formed on the outer circumferential side of the movable knife.

Further, the avoidance needle passing groove is arranged close to the common cutting edge, a section of transition surface distributed between the avoidance needle passing groove and the common cutting edge is arranged at the outer edge of the movable knife, and the transition surface is an inclined surface or an arc surface.

Further, the nest-less line cutting 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 provided with a wire dividing groove and a wire cutting and branching tip, the shared wire cutting edge and the wire cutting and branching tip are respectively arranged on two sides of the movable knife, and the wire dividing groove is distributed between the shared wire cutting edge and the wire cutting and branching tip.

Further, a post-sewing wire containing groove is formed in the surface of the movable knife, and the post-sewing wire containing groove is connected between the wire distributing groove and the common wire cutting edge.

Further, the movable knife is rotatably assembled below the sewing machine bottom plate; the bird nest less thread cutting mechanism further comprises a first thread cutting driving source, a thread cutting driving shaft rotatably supported in the sewing machine bottom plate, a first thread cutting crank fixed on the thread cutting driving shaft, a first thread cutting connecting rod and a movable cutter frame rotatably supported in the sewing machine bottom plate, wherein the first thread cutting driving source is connected with the thread cutting driving shaft, two ends of the first thread cutting connecting rod are hinged with the first thread cutting crank and the movable cutter frame respectively, and the movable cutter is fixed on the movable cutter frame.

Further, the auxiliary knife is fixed at the bottom of the sewing machine bottom plate.

Further, the auxiliary knife is movably assembled below the bottom plate of the sewing machine, and the bird nest less thread cutting mechanism further comprises a second thread cutting driving source which is in transmission connection with the auxiliary knife.

Further, the second wire cutting driving source is an air cylinder or an electromagnet.

Further, the second wire cutting driving source is a motor, the bird nest less wire cutting mechanism further comprises a second wire cutting crank and a second wire cutting connecting rod, wherein the second wire cutting crank and the second wire cutting connecting rod are fixed on a motor shaft of the second wire cutting driving source, and two ends of the second wire cutting connecting rod are hinged with the second wire cutting crank and the auxiliary knife respectively.

Further, a guide chute is formed in the bottom of the sewing machine bottom plate, and the auxiliary knife is movably assembled in the guide chute.

Further, the movable knife and the auxiliary knife are rotatably assembled below the sewing machine bottom plate; the bird nest less thread cutting mechanism further comprises a thread cutting driving motor, a first thread cutting cam, a second thread cutting cam, a first transmission mechanism and a second transmission mechanism, wherein the first thread cutting cam and the second thread cutting cam are both fixed on a motor shaft of the thread cutting driving motor, the first thread cutting cam is connected with the movable cutter through the first transmission mechanism, and the second thread cutting cam is connected with the auxiliary cutter 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.

Further, the first transmission mechanism comprises a first transmission shaft rotatably supported in the sewing machine bottom plate, a first transmission crank and a second transmission crank which are respectively fixed at two ends of the first transmission shaft, a first roller, a first transmission connecting rod and a first knife rest which are rotatably arranged at the outer end of the first transmission crank, the first roller is in butt fit with the outer peripheral surface of the first thread cutting cam, two ends of the first transmission connecting rod are respectively hinged with the second transmission crank and the first knife rest, and the movable knife is fixed on the first knife rest.

Further, the second transmission mechanism comprises a second transmission shaft rotatably supported in the bottom plate of the sewing machine, a third transmission crank and a fourth transmission crank which are respectively fixed at two ends of the second transmission shaft, a second roller, a second transmission connecting rod and a second knife rest, wherein the second roller, the second transmission connecting rod and the second knife rest are rotatably arranged at the outer end of the second transmission crank, the second roller is in butt fit with the outer peripheral surface of the second thread cutting cam, two ends of the second transmission connecting rod are respectively hinged with the fourth transmission crank and the second knife rest, and the auxiliary knife is fixed on the second knife rest.

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

As described above, the bird nest less thread cutting mechanism and the sewing machine according to the present utility model have the following advantages:

When the needle is used for starting the seam, firstly, the 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 upwards moved out of the seam starting thread hooking groove, the upper thread end is pulled out of a part of the upper thread end, and the upper 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 addition, the application sets the seam lifting cutting edge and the seam post cutting edge as the same shared cutting edge, adopts the existing cutting edge through hole as the seam lifting hooking groove, has simple structure and easy realization, can reduce the change of the movable knife in the existing sewing machine, and reduces the change cost.

Drawings

FIG. 1 is a schematic diagram of a first embodiment of a bird nest-less thread cutting mechanism.

Fig. 2 is a schematic structural view of a movable knife 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 view of a second embodiment of the bird nest-less trimming mechanism of the present application, showing only the movable blade and the auxiliary blade.

Fig. 9a to 9d are schematic diagrams of a second embodiment of a bird nest less thread cutting mechanism.

FIG. 10 is a schematic diagram of a third embodiment of a bird nest less thread cutting mechanism.

FIG. 11 is a schematic diagram of a fourth embodiment of a bird nest-less thread cutting mechanism.

FIG. 12 is a schematic diagram of a bird nest-less thread cutting mechanism according to a fifth embodiment 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. Cutting edge through hole

48. Transition surface

49. Line containing groove after sewing

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 bird nest less thread cutting mechanism. 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 thread cutting mechanism.

Embodiment one of a line cutting mechanism with fewer bird nests

As shown in fig. 1, the first embodiment of the bird nest-less thread cutting mechanism comprises an auxiliary blade 30 and a movable blade 40 capable of moving toward or away from the auxiliary blade 30; 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. 2, the movable blade 40 is provided with a line cutting edge, and a cutting edge through hole 47 penetrating up and down is arranged at the line cutting edge, and the line cutting edge and the cutting edge through hole 47 are of the existing structure on the movable blade 40. Meanwhile, the movable knife 40 is also provided with a seam lifting and hooking groove 41, a seam lifting and shearing edge and a seam post-shearing edge. In particular, the seam lifting and hooking groove 41 is a cutting edge through hole 47, or, when the existing cutting edge through hole 47 on the movable knife 40 is used as the seam lifting and hooking groove 41, the seam lifting and hooking groove 41 penetrates up and down through the movable knife 40 along the thickness direction of the movable knife 40, and the seam lifting and hooking groove 41 allows the needle 10 in the sewing machine to pass through. The seam lifting cutting edge and the seam post cutting edge are the same and are the existing cutting edges on the movable knife 40, the cutting edges are defined as a common cutting edge 42, the seam lifting cutting edge and the seam post cutting edge are the same common cutting edge 42, and the seam lifting hooking grooves 41 are 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.

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; then, the needle 10 moves up from the thread hooking groove 41 to withdraw a part of the thread end of the upper thread; then, the movable blade 40 moves in a direction approaching the auxiliary blade 30 until the common 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 a bird nest. 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. Therefore, the application can reliably realize the automatic thread trimming with less bird nest for starting and finishing the sewing. In addition, the application sets the seam starting cutting edge and the seam finishing cutting edge as the same shared cutting edge 42, adopts the existing cutting edge through hole 47 on the movable knife 40 as the seam starting cutting edge 41, so that the movable knife 40 has simple structure and easy realization, does not need to additionally process the cutting edge and the groove body forming the seam starting cutting edge 41 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.

Further, in the first embodiment of the bird nest-less thread cutting mechanism, the movable knife 40 is rotatably mounted under the sewing machine bottom plate 50, the rear end of the auxiliary knife 30 is fixed to the bottom of the sewing machine bottom plate 50 by a screw, and the movable knife 40 is moved back and forth to approach or separate 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 embodiment of the bird nest-less thread cutting 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. 2, the movable blade 40 is provided with a parting slot 43 and a parting tip 44, the common parting edge 42 and the parting tip 44 are respectively provided on the front side and the rear side of the movable blade 40, and the parting slot 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. 2, 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.

Further, the movable blade 40 may have a flat structure or a convex structure at the common cutting edge 42. In this embodiment, as shown in fig. 2, the movable blade 40 has a convex structure at the common cutting edge 42, that is, the movable blade 40 is provided with an upwardly protruding edge bulge 46 at the common cutting edge 42, and the edge through hole 47 is a through hole formed in the edge bulge 46. Preferably, the cutting-edge through-hole 47 has a circular hole structure, and the common cutting-edge 42 is a front edge portion of the cutting-edge through-hole 47. 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.

Further, a first lifting wing 412 extending backward is integrally provided at the right end side of the rear edge of the movable blade 40 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 bird nest less thread cutting mechanism, 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 mechanism further comprises a thread pressing plate 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.

Further, as shown in fig. 1, the first embodiment of the bird nest cutting mechanism comprises a suction device, wherein the suction device comprises a gas source and a suction pipe 70; the air source is arranged on the fixed frame, can be arranged on a bottom plate of the sewing machine, and can be directly placed on the ground; one end of the air suction pipe 70 is connected with an air source, and the other end of the air suction pipe 70 is an air suction inlet 71. The suction means is operated to provide continuous suction or intermittent suction when the head of the upper thread and the lower thread are cut by the starting stitch and when the cut surface and the lower thread are finished by the sewing machine, to achieve automatic collection after the head of the upper thread and the head of the lower thread are cut by the starting stitch and to achieve pre-catching of the lower thread 110 after the cut surface and the lower thread are finished by the sewing machine. The suction port 71 is mounted in the following two ways.

In the first embodiment, the suction port 71 is provided toward the outer peripheral surface of the rotating shuttle 20 in the radial direction of the rotating shuttle 20, that is, the suction port 71 is provided on the outer peripheral side of the rotating shuttle 20. Preferably, the air suction inlet 71 and the auxiliary knife 30 are arranged at the rear side of the needle 10, and the air suction inlet 71 is aligned with the seam lifting and hooking groove 41 of the movable knife 40.

In the second embodiment, as shown in fig. 1, the suction port 71 is provided toward the left end surface of the rotating shuttle 20 in the axial direction of the rotating shuttle 20, that is, the suction port 71 is provided on the left end side of the rotating shuttle 20. Preferably, the suction opening 71 is lower than the upper end of the rotating shuttle 20.

The following describes the working principle of the first embodiment of the bird's nest-less thread cutting mechanism, taking the configuration of the movable blade 40 and the auxiliary blade 30 to clamp the upper thread end in cooperation with each other, and the suction port 71 provided on the left end side of the rotating shuttle 20 as an example.

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, 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. 4b, preventing the upper thread end caught by the movable knife 40 from being wound into the normal stitch again to form a coil or being caught in the guide rail of the rotating shuttle 20; 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 thread cutting mechanism with less bird nests has a simple structure, can reduce the length of the bird nest and improve the sewing quality; 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 two of bird nest less thread cutting mechanism

The second embodiment of the bird nest less thread cutting mechanism differs from the first embodiment of the bird nest less thread cutting mechanism 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 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 the step 1.3 in the first embodiment of the bird nest cutting 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 mechanism with less bird nest

The third embodiment of the bird nest less thread cutting mechanism differs from the first embodiment of the bird nest less thread cutting mechanism 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 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 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 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 the step 1.3 in the first embodiment of the bird nest cutting 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 cutting mechanism with less bird nest

The fourth embodiment of the bird nest less thread cutting mechanism differs from the third embodiment of the bird nest less thread cutting mechanism 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 mechanism, as shown in fig. 11, the second thread cutting driving source 81 is a cylinder or an electromagnet, which 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 bird nest less thread cutting mechanism is the same as that of the third embodiment of the bird nest less thread cutting mechanism, and the description thereof will not be repeated here.

Embodiment five of bird nest less thread cutting mechanism

The fifth embodiment of the bird nest less thread cutting mechanism differs from the first embodiment of the bird nest less thread cutting mechanism 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 bird nest less thread cutting mechanism embodiment five further includes a thread cutting drive motor 91, a first thread cutting cam 92, a second thread 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 thread cutting 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 the step 1.3 in the first embodiment of the bird nest cutting 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 (18)

1. The utility model provides a little bird's nest trimming mechanism, includes auxiliary knife (30) and can be to being close to or keep away from movable knife (40) of auxiliary knife (30) direction motion, be equipped with on movable knife (40) and cut the line sword, cut line sword department and offered blade through-hole (47) that link up, its characterized in that: the movable knife (40) is also provided with a seam lifting and hooking groove (41), a seam lifting and shearing edge and a seam post-shearing edge, the seam lifting and hooking groove (41) is the edge through hole (47) and allows a needle (10) in the sewing machine to pass through, the seam lifting and shearing edge and the seam post-shearing edge are both the shearing edges, and the shearing edges form a common shearing edge (42);

When the sewing machine starts to sew, the shared cutting edge (42) can be meshed with the auxiliary knife (30) to cut the thread ends of the thread;

At the end of sewing by the sewing machine, the common cutting edge (42) can be engaged with the auxiliary knife (30) to cut the upper thread and the lower thread.

2. The bird nest less thread cutting 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 common cutting edge (42) is adjacent to the auxiliary knife (30) but is not meshed with the auxiliary knife.

3. The bird nest less thread cutting mechanism of claim 2, wherein: the avoidance needle passing groove (45) is a hollow area formed on the outer peripheral side of the movable knife (40).

4. A bird nest less thread cutting mechanism as set forth in claim 3, wherein: the avoidance needle passing groove (45) is adjacent to the common cutting edge (42), a transition surface (48) distributed between the avoidance needle passing groove (45) and the common cutting edge (42) is arranged at the outer edge of the movable knife (40), and the transition surface (48) is an inclined surface or an arc surface.

5. The bird nest less thread cutting mechanism of claim 2, 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.

6. The bird nest less thread cutting mechanism of claim 2, 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).

7. The bird nest less thread cutting mechanism of claim 1, wherein: the movable knife (40) is provided with a wire dividing groove (43) and a wire cutting and branching tip (44), the shared wire cutting edge (42) and the wire cutting and branching tip (44) are respectively arranged on two sides of the movable knife (40), and the wire dividing groove (43) is distributed between the shared wire cutting edge (42) and the wire cutting and branching tip (44).

8. The bird nest less thread cutting mechanism of claim 7, wherein: the surface of the movable knife (40) is provided with a post-sewing wire containing groove (49), and the post-sewing wire containing groove (49) is connected between the wire distributing groove (43) and the shared shearing edge (42).

9. The bird nest less thread cutting mechanism of claim 1, wherein: the movable knife (40) is rotatably assembled below the sewing machine bottom plate (50); the nest-less thread cutting mechanism further comprises a first thread cutting driving source (61), a thread cutting driving shaft (62) rotatably supported in the sewing machine bottom 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 bottom plate (50), the first thread cutting driving source (61) is connected with the thread cutting driving shaft (62), two ends of the first thread cutting connecting rod (64) are hinged with the first thread cutting crank (63) and the movable knife rest (65) respectively, and the movable knife (40) is fixed on the movable knife rest (65).

10. The bird nest less trimming mechanism of claim 1 or 9, wherein: the auxiliary knife (30) is fixed at the bottom of the sewing machine bottom plate (50).

11. The bird nest less trimming mechanism of claim 1 or 9, wherein: the auxiliary knife (30) is movably assembled below the sewing machine bottom plate (50), and the bird nest less thread cutting mechanism further comprises a second thread cutting driving source (81), and the second thread cutting driving source (81) is in transmission connection with the auxiliary knife (30).

12. The bird nest less thread cutting mechanism of claim 11, wherein: the second wire cutting driving source (81) is an air cylinder or an electromagnet.

13. The bird nest less thread cutting mechanism of claim 11, wherein: the second wire cutting driving source (81) is a motor, the wire cutting mechanism with less bird nest further comprises a second wire cutting crank (82) and a second wire cutting connecting rod (83), the second wire cutting crank (82) is fixed on a motor shaft of the second wire cutting driving source (81), and two ends of the second wire cutting connecting rod (83) are hinged with the second wire cutting crank (82) and the auxiliary knife (30) respectively.

14. The bird nest less thread cutting mechanism of claim 11, wherein: the bottom of the sewing machine bottom plate (50) is provided with a guide chute (51), and the auxiliary knife (30) is movably assembled in the guide chute (51).

15. The bird nest less thread cutting mechanism of claim 1, wherein: the movable knife (40) and the auxiliary knife (30) are rotatably assembled below the sewing machine bottom plate (50); the bird nest less thread cutting mechanism further comprises a thread cutting driving motor (91), a first thread cutting cam (92), a second thread cutting cam (93), a first transmission mechanism and a second transmission mechanism, wherein the first thread cutting cam (92) and the second thread cutting cam (93) are fixed on a motor shaft of the thread cutting driving motor (91), the first thread cutting cam (92) is connected with the movable knife (40) through the first transmission mechanism, and the second thread 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.

16. The bird nest less trimming mechanism of claim 15, wherein: the first transmission mechanism comprises a first transmission shaft (94) rotatably supported in a sewing machine bottom plate (50), a first transmission crank (95) and a second transmission crank (96) respectively fixed at two ends of the first transmission shaft (94), a first roller (97) rotatably mounted at the outer end of the first transmission crank (95), a first transmission connecting rod (98) and a first knife rest (99), wherein the first roller (97) is in butt fit with the outer peripheral surface of the first thread cutting cam (92), two ends of the first transmission connecting rod (98) are hinged with the second transmission crank (96) and the first knife rest (99) respectively, and the movable knife (40) is fixed on the first knife rest (99).

17. The bird nest less trimming mechanism of claim 15, wherein: the second transmission mechanism comprises a second transmission shaft (910) rotatably supported in the sewing machine bottom plate (50), a third transmission crank (911) and a fourth transmission crank (912) which are respectively fixed at two ends of the second transmission shaft (910), a second roller (913) rotatably installed at the outer end of the second transmission crank (96), a second transmission connecting rod (914) and a second knife rest (915), wherein the second roller (913) is in butt fit with the outer peripheral surface of the second thread cutting cam (93), two ends of the second transmission connecting rod (914) are respectively hinged with the fourth transmission crank (912) and the second knife rest (915), and the auxiliary knife (30) is fixed on the second knife rest (915).

18. A sewing machine, characterized in that: the sewing machine equipped with the bird nest-less thread cutting mechanism of any one of claims 1 to 17.