CN220907860U - Single-acting knife nest-preventing thread trimming mechanism and sewing machine - Google Patents

Abstract

The utility model provides a single-acting knife nest-preventing thread cutting mechanism and a sewing machine. The utility model adopts the same thread cutting driving source and the same set of movable cutters and fixed cutters to realize the purposes of preventing the seam from cutting the thread and finishing automatic thread cutting by sewing, effectively avoids seam starting and thread releasing, and realizes the normal seam starting and stabilizing effect of no bird nest thread ball during seam starting.

Description

Single-acting knife nest-preventing thread trimming mechanism and sewing machine

Technical Field

The utility model relates to the technical field of sewing machines, in particular to a single-acting knife bird nest preventing thread trimming mechanism and a sewing machine with the single-acting knife bird nest preventing thread trimming mechanism.

Background

A sewing machine is a machine that uses one or more sewing threads to form one or more stitches on a fabric, and interweaves or sews one or more layers of the fabric. The sewing machine mainly comprises a base (namely a machine shell and a bottom plate), a needle bar mechanism, a feeding mechanism, a thread hooking mechanism, a presser foot mechanism, a thread cutting mechanism and an accessory part, and the sewing materials are sewn together through reasonable matching of the movements of the mechanisms and circulation work.

In order to improve the sewing efficiency, automatic thread cutting equipment is generally adopted in the sewing equipment, so that not only is the sewing smooth, but also thread ends in clothes are reduced, and the subsequent finishing efficiency is improved. However, in the sewing process, the existing cutter can only cut the suture after the sewing process is finished, namely, can only realize automatic thread cutting after the sewing process is finished, but can not realize automatic thread cutting during the seam starting process. Therefore, when the needle is lifted for the second time, the thread end with a certain length is left on the needle, so that the needle lifting thread end can form nest-shaped thread end on the sewn clothes in the sewing process, the quality of the whole clothes is affected, and the quality of the whole clothes is affected. In order to ensure the quality of clothes, the thread ends are required to be manually trimmed, so that the manual strength is increased, and the production efficiency is affected.

In the prior art, some thread trimming mechanisms configured in sewing machines can achieve the effect of capturing upper threads by starting the sewing machine, for example, the thread trimming structure of the sewing machine disclosed in China patent application number 201720787765.3 cuts off the captured thread after the sewing machine runs for a certain angle, and achieves the thread trimming function again after the sewing is completed. However, as the thread cutting structure is arranged between the movable knife edge and the fixed knife edge, the control system immediately controls the motor to drive the knife to cut threads after the needle leaves the needle plate surface, the thread head of the upper thread is not interweaved too short in the thread cutting process, and the thread is not cut after the needle leaves the needle plate surface, and the follow-up sewing cannot be performed.

Disclosure of utility model

In view of the above-mentioned drawbacks of the prior art, an object of the present utility model is to provide a single-action knife bird nest-preventing thread cutting mechanism which is used for both seam lifting thread cutting and sewing finishing thread cutting, and can effectively avoid seam lifting thread releasing.

In order to achieve the above purpose, the utility model provides a single-acting knife nest-preventing thread cutting mechanism, which comprises a fixed knife, a rotatable movable knife, a thread cutting driving source and a thread cutting driving assembly, wherein the fixed knife is fixedly arranged, a fixed knife cutting edge is arranged on the fixed knife, the thread cutting driving source is in transmission connection with the movable knife through the thread cutting driving assembly, the movable knife is driven to rotate in a direction close to or far away from the fixed knife, a seam lifting thread hooking groove and a thread dividing thread hooking groove are formed in the movable knife, a needle in a sewing machine is allowed to pass through the seam lifting thread hooking groove, a movable cutting edge opening is formed in the surface of the movable knife facing the fixed knife, and the seam lifting thread hooking groove and the thread dividing thread hooking groove are distributed on the same side of the movable knife cutting edge.

Further, the movable knife is further provided with a seam-lifting line-containing groove and a seam-rear line-containing groove on the surface facing the fixed knife, the seam-lifting line-containing groove is connected between the seam-lifting line-hooking groove and the movable cutting edge opening, and the seam-rear line-containing groove is connected between the line-splitting line-hooking groove and the movable cutting edge opening.

Further, the single-acting knife bird nest preventing thread cutting mechanism further comprises an air suction pipe which is fixedly arranged, and the air suction pipe is provided with an air suction inlet which can be aligned with the seam lifting hook wire groove and/or the seam lifting containing wire groove.

Further, the wire cutting driving source is a motor; the method comprises the steps that in the range that a motor shaft of a wire cutting driving source rotates for 360 degrees, the wire cutting driving source is provided with a wire cutting working area, and the wire cutting working area is internally provided with an initial corner, a seam starting and cutting out corner, a seam back cutting out corner, a seam starting and cutting back tool holder line corner and a wire cutting corner;

when the thread cutting driving source is operated to the stitch-lifting cutter-discharging corner, the stitch-lifting thread hooking grooves are distributed right below the machine needle;

when the thread cutting driving source runs to a cutter outlet corner after sewing, the thread separating and hooking grooves are distributed right below the needle;

when the shearing driving source is operated to the line corner of the seam-starting back tool holder, the upper line on the surface of the movable tool is clamped, and the movable tool cutting edge and the fixed tool cutting edge are not meshed;

When the line cutting driving source is operated to a line cutting corner, the movable knife edge is meshed with the fixed knife edge.

Further, the wire cutting driving source is a motor; the thread cutting driving assembly comprises a thread cutting shaft rotatably supported in a sewing machine bottom plate, a first transmission assembly in transmission connection between a thread cutting driving source and the thread cutting shaft, and a second transmission assembly in transmission connection between the thread cutting shaft and the movable knife.

Further, the first transmission assembly comprises a first wire cutting crank fixed on a motor shaft of the wire cutting driving source, a first wire cutting connecting rod and a second wire cutting crank fixed on the wire cutting shaft, and two ends of the first wire cutting connecting rod are hinged with the first wire cutting crank and the second wire cutting crank respectively.

Further, the second transmission assembly comprises a third wire cutting crank, a second wire cutting connecting rod and a movable cutter frame, wherein the third wire cutting crank, the second wire cutting connecting rod and the movable cutter frame are fixed on the wire cutting shaft, two ends of the second wire cutting connecting rod are respectively hinged with the third wire cutting crank and the movable cutter frame, and the movable cutter is fixed on the movable cutter frame.

Further, a first line pressing part is arranged on the surface of the movable knife facing the fixed knife, and the first line pressing part is arranged on one side of the movable cutting edge opening facing the seam lifting hook line groove;

When the movable knife is driven by the line shearing driving source to rotate towards the direction close to the fixed knife so that the movable knife edge is close to the fixed knife edge and is not meshed with the fixed knife, the first line pressing part is abutted with the fixed knife, and a first line clamping seam for clamping the upper line is formed.

Further, the single-acting knife nest-preventing thread trimming mechanism further comprises a thread pressing plate which is fixedly arranged, and the thread pressing plate, the fixed knife and the movable knife are sequentially arranged from outside to inside along the radial direction of a rotating shuttle in the sewing machine; the surface of the movable knife facing the fixed knife is provided with a second line pressing part, and the second line pressing part is arranged on one side of the movable cutting edge opening, which is opposite to the seam lifting and hooking groove, and protrudes towards the line pressing plate along the thickness direction of the movable knife;

When the movable knife is driven by the line shearing driving source to rotate towards the direction close to the fixed knife so that the movable knife edge is close to the fixed knife edge and is not meshed with the fixed knife edge, the second line pressing part can be abutted with the line pressing plate, and a second line clamping seam for clamping the upper line is formed.

The application also provides a sewing machine, wherein the single-acting knife bird nest preventing thread cutting mechanism is assembled in the sewing machine.

As described above, the single-action knife bird nest-preventing thread trimming mechanism and the sewing machine provided by the utility model have the following beneficial effects:

The application controls the strokes of the movable knife at the beginning and the end of sewing by controlling the different strokes of the thread cutting driving source at the beginning and the end of sewing, thereby realizing thread cutting at the end of thread cutting at the beginning and the end of sewing, achieving the purposes of preventing the thread cutting from nesting at the beginning and finishing automatic thread cutting by the cooperation of the same thread cutting driving source, the same movable knife and the fixed knife. In particular, when the seam is lifted, the thread cutting driving source drives the movable cutter to drive the upper thread end to move towards the direction close to the fixed cutter but not to be meshed, the upper thread end on the surface of the movable cutter can be clamped, namely, the upper thread end is cut after the seam is lifted for setting the needle number, so that the seam lifting and thread releasing are effectively avoided, the normal seam lifting and stabilizing effect of the seam lifting without bird nest thread is realized, the attractive appearance of the stitch is ensured, and the manual trimming of the thread end is reduced. In addition, the application has the advantages of simple structure, easy realization, low cost, convenient control, higher control precision and improvement of the accuracy of seam starting and seam post-cutting.

Drawings

FIG. 1 is a schematic diagram of the assembly of the single-action knife bird nest-preventing thread cutting mechanism in a sewing machine according to the present application.

Fig. 2 and fig. 3 are schematic structural views of a single-action knife bird nest-preventing thread trimming mechanism under different viewing angles.

Fig. 4a is a schematic structural view of a first embodiment of the movable blade according to the present application.

Fig. 4b is a schematic structural view of a second embodiment of the movable blade according to the present application.

Fig. 4c is a schematic structural view of a third embodiment of the movable blade according to the present application.

FIG. 5 is a schematic view of a movable knife and stationary knife mating clamp line in accordance with the present application.

Fig. 6a is a schematic diagram of the movable knife and the line pressing plate matched line clamping in the application.

Fig. 6b is an enlarged view of circle a of fig. 6 a.

Fig. 7a is a schematic view of a first working angle of the wire cutting driving source according to the present application, which corresponds to the first movable blade embodiment in fig. 4 a.

Fig. 7b is a second schematic diagram of the working angle of the wire cutting driving source according to the present application, which corresponds to the second movable blade embodiment in fig. 4 b.

Fig. 8 is a state diagram of the single-acting knife nest-preventing thread trimming mechanism in the application when the seam is lifted out of the knife.

FIG. 9 is a state diagram of the single-action knife anti-bird nest thread cutting mechanism of the present application when the knife is unset back to the knife holder thread.

FIG. 10 is a state diagram of the single-action knife anti-bird nest thread cutting mechanism in the application when the knife is taken out after the seam.

Description of element reference numerals

10. Fixed knife

101. Fixed knife edge

20. Movable knife

21. Thread hooking groove for starting seam

22. Wire distributing groove

23. Movable cutting edge

24. Seam-lifting line-holding groove

25. Line containing groove after sewing

26. First line pressing part

27. Second line pressing part

30. Wire cutting driving source

40. Wire cutting driving assembly

41. Shearing shaft

42. First thread cutting crank

43. First trimming connecting rod

44. Second wire cutting crank

45. Third wire cutting crank

46. Second wire cutting connecting rod

47. Movable knife rest

50. Line pressing plate

60. Air suction pipe

70. Machine needle

80. Bottom plate

90. Rotating shuttle

110. Positioning hook

120. Motor support

P trimming work area

Α1 initial rotation angle

Alpha 2 seam-lifting knife-discharging corner

Alpha 3 seam post-cutting tool corner

Alpha 4 seam back tool holder line corner

Alpha 5 trimming corner

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," and "a" and the like are used herein for descriptive purposes only and not for purposes of limitation, and are intended to limit the scope of the utility model as defined by the claims and the relative terms thereof as construed as corresponding to the claims.

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 application relates to the technical field of sewing machines, in particular to a single-acting knife bird nest preventing thread cutting mechanism, a control method of the single-acting knife bird nest preventing thread cutting mechanism and a sewing machine provided with the single-acting knife bird nest preventing thread cutting mechanism. For convenience of description, in the following embodiments, the following directions are defined as follows: defining the axial directions of a main shaft and a lower shaft in the sewing machine as a left-right direction, wherein the left-right direction is a direction towards a machine head, and the right direction is a direction towards a machine tail, a rotating shuttle 90 in the sewing machine is fixed at the left end of the lower shaft, as shown in fig. 1; the moving direction of the sewing material driven by the feeding mechanism during the normal sewing of the sewing machine is defined as the front direction.

As shown in fig. 1 to 3, the single-acting knife nest-preventing thread trimming mechanism comprises a fixed knife 10, a rotatable movable knife 20, a thread trimming driving source 30 and a thread trimming driving assembly 40, wherein the fixed knife 10 is provided with a fixed knife cutting edge 101, and the thread trimming driving source 30 is in transmission connection with the movable knife 20 through the thread trimming driving assembly 40 to drive the movable knife 20 to rotate towards or away from the fixed knife 10. In the present embodiment, the stationary blades 10 are distributed on the rear side of the needle 70 in the front-rear direction, and the stationary blade edge 101 is provided at the front end of the stationary blade 10, as shown in fig. 5; when the movable knife 20 is driven by the wire cutting driving source 30 through the wire cutting driving assembly 40 to discharge the knife, the movable knife 20 rotates forwards and is far away from the fixed knife 10; when the wire cutting driving source 30 drives the movable knife 20 to return by the wire cutting driving assembly 40, the movable knife 20 rotates backwards and approaches the fixed knife 10. The movable blade 20 and the stationary blade 10 are both disposed on the lower side of the base plate 80 and on the outer peripheral side of the rotating shuttle 90, and the movable blade 20 is located on the lower side of the stationary blade 10 with the movable blade 20 being closer to the rotating shuttle 90 than the stationary blade 10. The rotating shuttle 90 is provided with a positioning hook 110 for limiting.

As shown in fig. 4a or fig. 4b, the movable knife 20 is provided with a seam lifting and hooking slot 21 and a branching and hooking slot 22, the seam lifting and hooking slot 21 and the branching and hooking slot 22 are communicated with the movable knife 20 along the thickness direction of the movable knife 20, and the seam lifting and hooking slot 21 allows a needle 70 in a sewing machine to pass through; the movable knife 20 is provided with a movable knife cutting edge 23 on the upper surface facing the fixed knife 10, and the seam lifting and hooking grooves 21 and the branching and hooking grooves 22 are distributed on the same side of the movable knife cutting edge 23, namely, on the rear side of the movable knife cutting edge 23. Along the direction away from the fixed knife 10 when the movable knife 20 is out, the arrangement modes of the seam lifting and hooking groove 21, the branching and hooking groove 22 and the movable knife cutting edge 23 can be as follows: 1. as shown in fig. 4a, in the first embodiment of the movable blade 20, along the direction away from the fixed blade 10 when the movable blade 20 is out of the blade, the seam lifting hook slot 21, the branching hook slot 22 and the movable blade edge 23 are distributed in sequence, i.e. the seam lifting hook slot 21, the branching hook slot 22 and the movable blade edge 23 are distributed in sequence from back to front; 2. as shown in fig. 4b, in the second embodiment of the movable blade 20, the parting line hooking groove 22, the starting line hooking groove 21 and the movable blade edge 23 are distributed sequentially along the direction away from the fixed blade 10 when the movable blade 20 is out of the blade, i.e. the parting line hooking groove 22, the starting line hooking groove 21 and the movable blade edge 23 are distributed sequentially from the rear to the front.

The application also provides a control method of the single-acting knife nest-preventing thread trimming mechanism, which sequentially comprises the following steps:

Step S1, configuring a controller, enabling the thread cutting driving source 30 to be in communication connection with the controller, simultaneously enabling a main motor driving a main shaft in the sewing machine to rotate to be in communication connection with the controller, and enabling the left end of the main shaft to drive a needle 70 to reciprocate up and down through a needle bar mechanism.

Step S2, a first needle is started by the sewing machine, and the needle 70 moves downwards and then upwards; during the downward movement of the first needle 70 of the sewing machine or before the first needle 70 of the sewing machine is started, the controller controls the thread cutting driving source 30 to operate, the movable cutter 20 is driven to move out by the thread cutting driving assembly 40, the movable cutter 20 is rotated forwards in a direction away from the fixed cutter 10 until the movable cutter 20 is rotated to a starting and discharging position, and at this time, as shown in fig. 8, the starting and hooking groove 21 is rotated to a position right below the needle 70. Preferably, when the sewing machine is started up, or after the last sewing is finished, the controller controls the thread cutting driving source 30 to operate, so that the movable knife 20 rotates to the stitch-lifting knife-discharging position, and the stitch-lifting thread hooking groove 21 is rotated to be right below the needle 70 before the first needle 70 is lifted up by the sewing machine.

In step S3, the first needle 70 of the sewing machine moves downward, and since the needle lifting and hooking groove 21 is located right under the needle 70, the needle 70 penetrates the needle lifting and hooking groove 21 with the upper thread downward, and the upper thread end moves under the movable knife 20 under the action of the rotating shuttle 90 in the sewing machine.

Step S4, the sewing machine continues to stitch the first needle, and the needle 70 moves upwards; when the needle 70 passes through the seam lifting and hooking groove 21 upwards, the controller controls the thread cutting driving source 30 to reversely rotate, the thread cutting driving assembly 40 drives the movable cutter 20 to return to the cutter, so that the movable cutter 20 rotates backwards in the direction close to the fixed cutter 10 until the movable cutter 20 rotates to the seam lifting and returning cutter holder line position, as shown in fig. 9, the seam lifting and hooking groove 21 rotates backwards towards the fixed cutter 10 with the upper thread end, and the upper thread end is accommodated on the surface of the movable cutter 20 and is clamped; in particular, when the movable blade 20 is sewn back to the holder thread position, the movable blade edge 23 is not engaged with the fixed blade edge 101, and the upper thread end on the surface of the movable blade 20 is clamped but not cut.

Step S5, the sewing machine continues to set the needle number in a seam starting mode, in the process, the movable cutter cutting edge 23 and the fixed cutter cutting edge 101 keep a non-meshed state, as shown in FIG. 9, the upper thread end is always on the surface of the movable cutter 20, is clamped and not sheared, and effectively prevents thread off.

And S6, the controller controls the thread cutting driving source 30 to continue to reversely run, the thread cutting driving assembly 40 drives the movable cutter 20 to continue to return the cutter, so that the movable cutter 20 rotates backwards in the direction close to the fixed cutter 10 until the movable cutter 20 rotates to a thread cutting position, and at the moment, the movable cutter cutting edge 23 is meshed with the fixed cutter cutting edge 101, and the upper thread head on the surface of the movable cutter 20 is cut off. So far, through step S2 to step S6, the seam starting, trimming and bird nest prevention is realized.

And S7, the sewing machine performs normal sewing.

In step S8, when the sewing machine finishes the sewing and needs to cut the thread, the controller simultaneously controls the thread cutting driving source 30 to operate in the process of sewing the last needle 70 by the sewing machine, and drives the movable knife 20 to move out of the knife through the thread cutting driving assembly 40, so that the movable knife 20 rotates forward in the direction away from the fixed knife 10 until the movable knife 20 rotates to the post-sewing out-knife position, as shown in fig. 10, and thread hooking and branching are performed.

Step S9, the controller controls the thread cutting driving source 30 to reversely run, the thread cutting driving assembly 40 drives the movable cutter 20 to return to the cutter, so that the movable cutter 20 rotates backwards in the direction close to the fixed cutter 10 until the movable cutter 20 rotates to a thread cutting position, and in the process, the thread cutting groove 22 rotates towards the fixed cutter 10 with the upper thread and the bottom thread, and the upper thread is accommodated on the surface of the movable cutter 20; after the movable knife 20 rotates to the line cutting position, the movable knife edge 23 is meshed with the fixed knife edge 101 to cut off the upper line and the lower line. Thus, through the step S8 and the step S9, automatic thread trimming at the end of sewing is realized.

In the application, a seam lifting and hooking groove 21 and a branching and hooking groove 22 are arranged on a movable knife 20, and a controller is combined to control different strokes of a thread cutting driving source 30 when seam lifting and sewing are finished so as to control the strokes of the movable knife 20 when seam lifting and sewing are finished. During seam starting, the movable cutter 20 rotates forwards to a seam starting and cutter discharging position, then rotates backwards to a seam starting and cutter holder thread returning position with the upper thread end, and finally rotates backwards to a thread shearing position after the seam starting is performed for setting the needle number, so that the thread end of the section thread is sheared during seam starting. When the sewing is finished and the thread is cut, the movable cutter 20 rotates forwards to a position of a cutter outlet after sewing and then rotates backwards to a thread cutting position with the upper thread, so that automatic thread cutting is realized when the sewing is finished. Therefore, the application achieves the purposes of preventing the seam from being cut and preventing the bird nest and finishing automatic seam cutting by sewing by the same thread cutting driving source 30, the same set of movable cutters 20 and fixed cutters 10.

Particularly, when the movable knife 20 is driven by the thread cutting driving source 30 to drive the upper thread end to move to the direction close to the fixed knife 10 and to the thread lifting and returning position of the knife holder during thread lifting, the upper thread end on the surface of the movable knife 20 can be clamped, but the movable knife blade 23 is not meshed with the fixed knife blade 101, and the thread cutting driving source 30 drives the movable knife 20 to drive the upper thread end to rotate backwards to the thread cutting position for thread cutting after the thread lifting and setting number of needles, namely, the upper thread end is cut after the thread lifting and setting number of needles, and the upper thread end is always clamped during the thread lifting and setting number of needles, so that the stable effect of normal thread lifting without bird nest stitch is realized, the beautiful appearance of the thread is ensured, and the manual thread cutting is reduced. In addition, the application has the advantages of simple structure, easy realization and low cost; the controller controls the movable knife 20 only by controlling the thread cutting driving source 30, is convenient to control, has higher control precision, and improves the accuracy of seam starting thread cutting and seam post-thread cutting.

Based on the fact that the upper thread ends need to be clamped when the seam is lifted and cut, the single-acting knife nest-preventing thread cutting mechanism further comprises a thread clamping unit, and when the movable knife 20 is located at the seam lifting and cutting clamp thread position, the thread clamping unit acts on the upper thread ends on the surface of the movable knife 20 to clamp the upper thread ends on the surface of the movable knife 20. In this embodiment, the wire clamping unit has the following two preferred embodiments.

First embodiment of the thread clamping unit is formed by a movable blade 20 and a stationary blade 10. As shown in fig. 5, a first pressing line portion 26 is provided on the upper surface of the movable knife 20 facing the fixed knife 10, and the first pressing line portion 26 is provided on the rear side of the movable knife edge 23 facing the suture hooking groove 21. When the movable knife 20 is driven by the thread cutting driving source 30 to rotate backward to the position of the thread cutting back to the knife holder, the movable knife edge 23 is adjacent to the fixed knife edge 101, but is not engaged, the first thread pressing part 26 abuts against the fixed knife 10, and a first thread clamping slot for clamping the thread end of the upper thread is formed, and the thread clamping unit in the first embodiment is composed of the abutting first thread pressing part 26 and the fixed knife 10.

The second embodiment of the wire clamping unit is formed by the movable blade 20 and the wire pressing plate 50. As shown in fig. 6a and 6b, the single-acting knife nest-preventing thread trimming mechanism further comprises a thread pressing plate 50 fixedly arranged, wherein the thread pressing plate 50, the fixed knife 10 and the movable knife 20 are sequentially arranged from outside to inside along the radial direction of the rotating shuttle 90 in the sewing machine, the thread pressing plate 50 is arranged on the upper side of the fixed knife 10, and the thread pressing plate 50 is fixed on the bottom of the bottom plate 80 through screws. The movable knife 20 is provided with a second line pressing part 27 on the surface facing the fixed knife 10, the second line pressing part 27 is arranged on the front side of the movable knife cutting edge 23, which is opposite to the seam hooking groove 21, and protrudes upwards towards the line pressing plate 50 along the thickness direction of the movable knife 20, and the front end of the line pressing plate 50 passes forward beyond the fixed knife cutting edge 101 at the front end of the fixed knife 10. When the movable knife 20 is driven by the thread cutting driving source 30 to rotate backward to the position of the thread cutting back to the knife holder, the movable knife edge 23 is adjacent to the fixed knife edge 101, but is not engaged, the second thread pressing portion 27 abuts against the thread pressing plate 50, and forms a second thread clamping slit for clamping the upper thread, and the second thread clamping unit embodiment is composed of the abutting second thread pressing portion 27 and the thread pressing plate 50.

Preferably, as shown in fig. 4a or fig. 4b, the upper surface of the movable knife 20 facing the fixed knife 10 is also provided with a seam-lifting groove 24 and a seam-following groove 25, the seam-lifting groove 24 is connected between the seam-lifting hook groove 21 and the movable blade opening 23, that is, the rear end of the seam-lifting groove 24 extends backwards to the seam-lifting hook groove 21, and the front end extends forwards to the movable blade opening 23; the slot-behind slot-accommodating groove 25 is connected between the wire-separating and hooking groove 22 and the movable blade opening 23, namely, the rear end of the slot-behind slot-accommodating groove 25 extends backwards to the wire-separating and hooking groove 22, and the front end extends forwards to the movable blade opening 23. The slot-forming slot 24 and the slot-forming slot 25 both play a guiding role. In the first embodiment of the movable blade 20, as shown in fig. 4a, the post-suture containing groove 25 is a front section of the suture-starting containing groove 24, and the suture-branching groove 22 is disposed on the extending path of the suture-starting containing groove 24; when the seam is lifted and cut, the seam lifting and containing groove 24 accommodates an upper thread head, and a part of the upper thread head is simultaneously accommodated in the seam post-containing groove 25 forming the front section part of the seam lifting and containing groove 24; when the thread is cut after sewing, the upper thread and the lower thread are accommodated in the thread accommodating groove 25 after sewing. In the second embodiment of the movable knife 20, as shown in fig. 4b, the seam-lifting line containing groove 24 is a front section of the seam-rear line containing groove 25, and the seam-lifting hook line containing groove 21 is disposed on an extending path of the seam-rear line containing groove 25; when the seam is lifted and cut, the seam lifting containing groove 24 accommodates the upper thread head; when the thread is cut after sewing, the upper thread and the lower thread are accommodated in the post-sewing thread accommodating groove 25, and then a part of the upper thread and the lower thread are simultaneously accommodated in the thread-raising thread accommodating groove 24 constituting the front section of the post-sewing thread accommodating groove 25.

Further, as shown in fig. 4a to 4c, the parting line hooking groove 22 is an opening groove opened to the left, and the starting line hooking groove 21 may be either an opening groove or a closing groove; such as: in the movable knife 20 shown in fig. 4a and 4b, the suture hooking groove 21 is a closed groove; in the movable knife 20 shown in fig. 4c, the seam hooking groove 21 is an open groove opened backward; in other embodiments, the seam hooking groove 21 may also be an open groove that opens to the left.

Further, as shown in fig. 2 and 3, the single-acting knife bird nest preventing thread cutting mechanism further comprises an air suction pipe 60 fixedly arranged, the air suction pipe 60 is fixed at the bottom of the bottom plate 80 through screws, the air suction pipe 60 is provided with an air suction inlet which can be aligned with the seam lifting hook wire groove 21 and/or the seam lifting containing wire groove 24, the air suction pipe 60 is connected with an air source generating device, and the air source generating device is in communication connection with the controller. In the process of seam starting and thread trimming for preventing bird nest, when the controller controls the thread trimming driving source 30 to drive the movable knife 20 to rotate forwards, the controller also controls the air source generating device to start, so that the negative pressure thread sucking action is generated at the air suction inlet of the air suction pipe 60; thus, when the movable knife 20 drives the upper thread head to rotate backwards to the position of the seam lifting and back-cutting clamp, the upper thread head in the seam lifting and back-cutting groove 21 is just in the negative pressure area of the air suction port, so that the pick-up of the upper thread head end of the upper thread head is realized; after the seam is lifted and the thread is cut, the cut upper thread ends are sucked away by the negative pressure of the suction inlet, so that the collection of the upper thread ends is realized.

Preferably, as shown in fig. 1, the stationary knife 10 is fixed to the bottom of the sewing machine base plate 80 by screws, thereby realizing a fixed arrangement of the stationary knife 10. Thus, the fixed knife 10, the line pressing plate 50 and the air suction pipe 60 can be fixed at the bottom of the bottom plate 80 through the same screw.

Further, the wire cutting driving source 30 drives the movable blade 20 to rotate around the lower shaft, that is, the rotation center of the movable blade 20 is the lower shaft, through the wire cutting driving assembly 40. As shown in fig. 2 and 3, the wire cutting driving source 30 is a motor, preferably a stepping motor, and the wire cutting driving source 30 is fixed to a motor bracket 120, and the motor bracket 120 is fixed to the bottom of the base plate 80 by a plurality of screws. Of course, the wire cutting driving source 30 may be directly fixed to the bottom of the base plate 80 by a plurality of screws.

Further, as shown in fig. 2 and 3, the thread cutting driving assembly 40 includes a thread cutting shaft 41 rotatably supported in the sewing machine base plate 80, a first transmission assembly drivingly connected between the thread cutting driving source 30 and the right end of the thread cutting shaft 41, and a second transmission assembly drivingly connected between the left end of the thread cutting shaft 41 and the movable knife 20. The shear spool 41 is parallel to the lower shaft, and the shear spool 41 is rotatably supported in the bottom plate 80 of the sewing machine by a bush. The wire cutting driving source 30 drives the wire cutting shaft 41 to rotate through the first transmission assembly, and the wire cutting shaft 41 drives the movable knife 20 to rotate through the second transmission assembly.

Further, as shown in fig. 2 and 3, the first transmission assembly includes a first wire cutting crank 42 fixed on a motor shaft of the wire cutting driving source 30, a first wire cutting link 43, and a second wire cutting crank 44 fixed on a right end of the wire cutting shaft 41, both ends of the first wire cutting link 43 being hinged with the first wire cutting crank 42 and the second wire cutting crank 44, respectively. The second transmission assembly comprises a third wire cutting crank 45 fixed at the left end of the wire cutting shaft 41, a second wire cutting connecting rod 46 and a movable tool rest 47, wherein two ends of the second wire cutting connecting rod 46 are respectively hinged with the third wire cutting crank 45 and the movable tool rest 47, and the movable tool 20 is fixed on the movable tool rest 47 through screws.

Further, as shown in fig. 7a or 7b, the wire cutting driving source 30 has a wire cutting work area P having an initial rotation angle α1, a stitch pull-out knife rotation angle α2, a stitch pull-out knife rotation angle α3, a stitch pull-back holder wire rotation angle α4, and a wire cutting rotation angle α5 within a range in which the motor shaft of the wire cutting driving source 30 rotates one turn 360 °. For the first embodiment of the movable blade 20 shown in fig. 4a, as shown in fig. 7a, the initial rotation angle α1, the trimming rotation angle α5, the seam-lifting and back-cutting tool holder rotation angle α4, the seam-lifting and back-cutting tool outlet rotation angle α3 and the seam-lifting and back-cutting rotation angle α2 are sequentially set, and the trimming working area P ranges from α1 to α2. For the second embodiment of the movable blade 20 shown in fig. 4b, as shown in fig. 7b, the initial rotation angle α1, the trimming rotation angle α5, the seam-lifting and back-cutting tool holder rotation angle α4, the seam-lifting and out-cutting rotation angle α2 and the seam-post-out-cutting rotation angle α3 are sequentially set, and the range of the trimming working area P is α1 to α3. When the thread cutting driving source 30 is operated to the stitch raising and thread discharging angle alpha 2, the movable knife 20 is rotated to the stitch raising and thread discharging position, and the stitch raising and thread hooking grooves 21 are distributed right below the needle 70. When the thread cutting drive source 30 is operated to the post-sewing cutter-out rotation angle alpha 3, the movable cutter 20 is rotated to the post-sewing cutter-out position, and the thread-separating and thread-hooking grooves 22 are distributed right below the needle 70. When the thread cutting driving source 30 is operated to the seam allowance return tool holder thread turning angle alpha 4, the movable cutter 20 is rotated to the seam allowance return tool holder thread position, the upper thread in the seam allowance groove 24 is clamped, and the movable cutter edge opening 23 is not engaged with the fixed cutter edge 101. When the wire cutting drive source 30 is operated to the wire cutting rotation angle α5, the movable blade 20 is rotated to the wire cutting position, and the movable blade edge 23 is engaged with the fixed blade edge 101.

In summary, the working principle of the single-action knife anti-nest thread trimming mechanism according to the present application is as follows, and the first embodiment of the movable knife 20 and the thread pressing plate 50 are taken as an example.

1. The single-acting knife bird nest preventing and thread cutting mechanism is used for starting a seam, cutting threads and preventing bird nest and comprises the following steps:

A1, the sewing machine works, a main shaft rotates, a first needle is lifted, a controller controls a thread cutting driving source 30 to synchronously move, the thread cutting driving source 30 rotates to a lifting cutter rotating angle alpha 2, a movable cutter 20 is driven to rotate forwards to a lifting cutter position, and a lifting thread hooking groove 21 rotates to the position right below a needle 70; or the controller has controlled the thread cutting drive source 30 to rotate to the stitch raising and cutting angle alpha 2 before the sewing machine starts the first needle, and has rotated the stitch raising and cutting groove 21 to the position right below the needle 70. Meanwhile, the controller controls the air source generating device to act, so that negative pressure suction line acts at the suction inlet of the suction pipe 60.

A2, the first needle 70 of the sewing machine moves downwards, and after the needle 70 passes through the sewing thread hooking groove 21 with the upper thread downwards, the upper thread end on one side of the needle 70 is driven to the lower part of the movable knife 20 under the action of the rotating shuttle 90.

A3, the first needle 70 of the sewing machine for starting the seam moves upwards, after the needle 70 is upwards far away from the movable knife 20, the controller controls the thread cutting driving source 30 to reversely rotate from a starting seam outlet knife corner alpha 2 to a starting seam return tool holder thread corner alpha 4, the movable knife 20 is retracted backwards to a starting seam return tool holder thread position with the upper thread end, the thread pressing plate 50 is abutted with the second thread pressing part 27 of the movable knife 20, and the upper thread end in the starting seam containing slot 24 is clamped; the thread end of the surface thread end in the thread holding groove 24 is positively beneficial to the negative pressure area of the air suction port, so that the thread end is picked up; when the movable blade edge 23 and the fixed blade edge 101 are in a non-engagement state, the upper thread end is only clamped and not sheared.

A4, after the sewing machine continues to set the needle number for starting the seam, the controller controls the thread cutting driving source 30 to continuously reversely rotate from the seam starting back to the thread cutting corner alpha 4 to the thread cutting corner alpha 5, the movable cutter 20 drives the upper thread end to reversely rotate to the thread cutting position, the movable cutter cutting edge 23 is meshed with the fixed cutter cutting edge 101, the upper thread end in the seam starting thread accommodating groove 24 is cut off, and the cut upper thread end is sucked away by the negative pressure of the air suction port and is collected.

A5, the controller controls the wire cutting driving source 30 to continuously reversely rotate from the wire cutting rotation angle alpha 5 to the initial rotation angle alpha 1, the movable knife 20 is restored to the initial position, the controller controls the air source generating device to stop acting, and the air suction pipe 60 cuts off air suction; then, the sewing machine is used for sewing according to the set state.

2. The single-acting knife bird nest preventing thread cutting mechanism is used for cutting threads when sewing is finished, and comprises the following steps:

B1, the sewing machine sews the last needle, in the process of upward movement of the needle 70, the controller controls the thread cutting driving source 30 to synchronously move, the thread cutting driving source 30 rotates to a post-sewing cutter outlet angle alpha 3, the movable cutter 20 is driven to rotate forward to a post-sewing cutter outlet position, and thread hooking and branching are realized by the thread hooking groove 22.

B2, the controller controls the thread cutting driving source 30 to reversely rotate from the post-sewing cutter outlet angle alpha 3 to the thread cutting angle alpha 5, the movable cutter 20 rotates to the thread cutting position backwards with the upper thread and the bottom thread, the movable cutter cutting edge 23 is meshed with the fixed cutter cutting edge 101, and the upper thread and the bottom thread in the post-sewing thread accommodating groove 25 are cut off.

Therefore, the single-acting knife nest-preventing thread trimming mechanism has the following advantages:

1. the movable knife 20 is provided with a seam lifting hook wire groove 21, a branching hook wire groove 22, a seam lifting containing wire groove 24 and a seam post-containing wire groove 25, and the same movable knife 20 is matched with the fixed knife 10 to realize two functions: the seam is lifted and cut to prevent bird nest and automatic seam cutting after seam cutting.

2. After the needle thread is lifted, the upper thread end is brought to one side of the needle 70 to stay for waiting, the upper thread end is always clamped in the waiting process, the upper thread end is cut after the needle thread is lifted for a set number of needles, the cutting waiting time of the upper thread end is accurately controlled according to the set number of needles, and therefore, the needle thread lifting and dropping can be avoided, and bird nest thread coils can be avoided.

3. The stepping motor is adopted for driving, the wire cutting is stable and reliable, and the wire cutting noise is low.

In the above embodiment, the stationary blade 10, the movable blade 20, the pressing plate 50 and the air suction duct 60 are all disposed at the rear side of the needle 70; in other embodiments, the fixed blade 10, the movable blade 20, the pressing plate 50 and the air suction pipe 60 may be symmetrically disposed at the front side of the needle 70 along the central axis of the rotating shuttle, so that the movable blade 20 swings backward when it comes out and swings forward when it returns.

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 bird's nest thread cutting mechanism is prevented to single acting knife, includes stationary knife (10), rotatable movable knife (20), cuts line actuating source (30) and cuts line actuating component (40) of fixed setting, be equipped with stationary knife blade (101) on stationary knife (10), cut line actuating source (30) are connected through cutting line actuating component (40) and movable knife (20) transmission, the drive movable knife (20) are rotated to the direction that is close to or keeps away from stationary knife (10), its characterized in that: the movable knife (20) is provided with a seam lifting and hooking groove (21) and a branching and hooking groove (22), the seam lifting and hooking groove (21) allows a needle (70) in a sewing machine to pass through, the movable knife (20) is provided with a movable knife cutting edge (23) on the surface facing the fixed knife (10), and the seam lifting and hooking groove (21) and the branching and hooking groove (22) are distributed on the same side of the movable knife cutting edge (23).

2. The single action knife bird nest thread cutting prevention mechanism of claim 1, wherein: the movable knife (20) is further provided with a seam-lifting line-containing groove (24) and a seam-rear line-containing groove (25) on the surface facing the fixed knife (10), the seam-lifting line-containing groove (24) is connected between the seam-lifting line-hooking groove (21) and the movable knife cutting edge (23), and the seam-rear line-containing groove (25) is connected between the seam-lifting line-hooking groove (22) and the movable knife cutting edge (23).

3. The single action knife bird nest thread cutting prevention mechanism of claim 2, wherein: the air suction pipe (60) is fixedly arranged, and the air suction pipe (60) is provided with an air suction inlet which can be aligned with the seam lifting hook wire groove (21) and/or the seam lifting containing wire groove (24).

4. The single action knife bird nest thread cutting prevention mechanism of claim 1, wherein: the wire cutting driving source (30) is a motor; in the range that a motor shaft of the thread cutting driving source (30) rotates for 360 degrees, the thread cutting driving source (30) is provided with a thread cutting working area (P), and an initial corner (alpha 1), a seam starting and cutting out corner (alpha 2), a seam finishing and cutting out corner (alpha 3), a seam starting and cutting back corner (alpha 4) and a thread cutting corner (alpha 5) are arranged in the thread cutting working area (P);

When the thread cutting driving source (30) runs to a stitch-lifting and thread-cutting corner (alpha 2), the stitch-lifting and thread-cutting grooves (21) are distributed under the machine needle (70);

When the thread cutting driving source (30) runs to a post-sewing cutter outlet corner (alpha 3), the thread separating and hooking grooves (22) are distributed under the needle (70);

when the shearing driving source (30) is operated to a seam-lifting and tool-returning clamp line corner (alpha 4), the surface line of the movable knife (20) is clamped, and the movable knife cutting edge (23) is not meshed with the fixed knife cutting edge (101);

When the wire cutting driving source (30) is operated to a wire cutting corner (alpha 5), the movable cutter cutting edge (23) is meshed with the fixed cutter cutting edge (101).

5. The single action knife bird nest thread cutting prevention mechanism of claim 1, wherein: the wire cutting driving source (30) is a motor; the thread cutting drive assembly (40) comprises a thread cutting shaft (41) rotatably supported in a sewing machine base plate (80), a first transmission assembly in transmission connection between the thread cutting drive source (30) and the thread cutting shaft (41), and a second transmission assembly in transmission connection between the thread cutting shaft (41) and the movable knife (20).

6. The single action knife bird nest thread cutting mechanism of claim 5, wherein: the first transmission assembly comprises a first wire cutting crank (42) fixed on a motor shaft of the wire cutting driving source (30), a first wire cutting connecting rod (43) and a second wire cutting crank (44) fixed on the wire cutting shaft (41), and two ends of the first wire cutting connecting rod (43) are hinged with the first wire cutting crank (42) and the second wire cutting crank (44) respectively.

7. The single action knife bird nest thread cutting mechanism of claim 5, wherein: the second transmission assembly comprises a third wire cutting crank (45), a second wire cutting connecting rod (46) and a movable cutter frame (47), wherein the third wire cutting crank (45) is fixed on the wire cutting shaft (41), two ends of the second wire cutting connecting rod (46) are respectively hinged with the third wire cutting crank (45) and the movable cutter frame (47), and the movable cutter (20) is fixed on the movable cutter frame (47).

8. The single action knife bird nest thread cutting prevention mechanism of claim 1, wherein: the surface of the movable knife (20) facing the fixed knife (10) is provided with a first line pressing part (26), and the first line pressing part (26) is arranged at one side of the movable knife edge opening (23) facing the seam lifting and hooking groove (21);

when the movable knife (20) is driven by the line cutting driving source (30) to rotate towards the direction close to the fixed knife (10) and the movable knife cutting edge (23) is adjacent to the fixed knife cutting edge (101) and is not meshed, the first line pressing part (26) is abutted with the fixed knife (10) and forms a first line clamping seam for clamping an upper line.

9. The single action knife bird nest thread cutting prevention mechanism of claim 1, wherein: the sewing machine also comprises a thread pressing plate (50) which is fixedly arranged, wherein the thread pressing plate (50), the fixed knife (10) and the movable knife (20) are sequentially arranged from outside to inside along the radial direction of a rotating shuttle (90) in the sewing machine; the movable knife (20) is provided with a second line pressing part (27) on the surface facing the fixed knife (10), and the second line pressing part (27) is arranged on one side of the movable knife edge opening (23) facing away from the seam lifting and hooking groove (21) and protrudes towards the line pressing plate (50) along the thickness direction of the movable knife (20);

When the movable knife (20) is driven by the line cutting driving source (30) to rotate towards the direction close to the fixed knife (10) so that the movable knife edge (23) is close to the fixed knife edge (101) and is not meshed, the second line pressing part (27) can be abutted with the line pressing plate (50) to form a second line clamping seam for clamping the upper line.

10. A sewing machine, characterized in that: the single-acting knife nest-preventing thread trimming mechanism of any one of claims 1 to 9 is arranged in the sewing machine.