CN109487453B - Double-moving-knife thread shearing device of sewing machine - Google Patents

Abstract

The invention provides a double-moving-blade thread cutting device of a sewing machine, which comprises a first moving blade and a second moving blade which are movably arranged on a main needle plate, wherein a first blade on the first moving blade and a second blade on the second moving blade can be meshed, and the double-moving-blade thread cutting device also comprises a first driving source, a second driving source, a first driving assembly and a second driving assembly, wherein the first driving source is connected with the first moving blade through the first driving assembly and drives the first moving blade to move, and the second driving source is connected with the second moving blade through the second driving assembly and drives the second moving blade to move. In this application, drive respectively by two independent driving sources and move the sword motion with the second for first move the sword and the second move the sword and do not have linkage nature between the two, thereby have better adjustability and controllability, can realize the trimming effect of stub steadily.

Description

Double-moving-knife thread shearing device of sewing machine

Technical Field

The invention relates to a sewing machine, in particular to a double-moving-knife thread shearing device of the sewing machine.

Background

At present, the requirement of customers on the thread ends of clothes is higher and higher, the length of the thread ends directly influences the attractiveness of the clothes, and in addition, the thread ends are too long and are easy to have the hidden trouble of thread loosening caused by pulling the thread ends. In order to solve the problem of overlong thread ends, the common practice of the current clothing factories is as follows: a procedure of manually trimming thread ends is added, but the method increases the labor cost of garment making and reduces the production efficiency of garment making; alternatively, some sewing machine manufacturers also make improvements in the thread trimming device of the sewing machine to achieve the thread trimming effect of the stub. In the prior art, a thread cutting device in a sewing machine mainly has two forms: single-moving-knife thread-cutting device and double-moving-knife thread-cutting device. The fixed knife is arranged on the needle plate, the needle hole is arranged on the needle plate, the fixed knife is arranged on the needle plate, and the fixed knife is arranged on the needle plate. The double-action-knife thread cutting device is provided with two movable knives, such as: the double-knife thread trimming mechanism of the sewing machine disclosed in the chinese utility model patent specification with the application number of 201520727456.8 adopts a driving source to drive a first moving knife and a second moving knife simultaneously, thereby realizing thread trimming; however, the double-action-knife thread cutting mechanism has the following defects: 1. the two moving blades are connected to the same driving rod through a mechanical structure, so that the two moving blades are in a linkage structure and act simultaneously, and certain mutual limitation exists between the two moving blades; 2. the double-knife thread cutting mechanism is connected through a plurality of connecting rod mechanisms, and the ideal thread cutting position, the limit of each part and the flexible movement of each part are realized at a needle falling hole by matching among the parts, so that the double-knife thread cutting mechanism has over-strong relevance and poor adjustability; 3. the two movable cutters act simultaneously to realize thread cutting in a matching way, so that the thread cutting effect is influenced by the two movable cutters, and the thread cutting stability is poor; 4. the line cutting is realized at the needle falling hole, so that the meeting and the meshing of the cutting edges of the two movable cutters at the needle falling hole in the return stroke process are required to be ensured, the limit advancing position of the second movable cutter is also required to be ensured to be positioned right below the needle falling hole, but the ideal line cutting position is difficult to adjust due to the relevance of the actions of the two movable cutters, and the line cutting effect is not ideal.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, it is an object of the present invention to provide a double-knife thread trimmer device for a sewing machine with improved adjustability and controllability.

In order to achieve the purpose, the invention provides a double-moving-blade thread cutting device of a sewing machine, which comprises a first moving blade and a second moving blade which are movably arranged on a main needle plate, wherein a first blade on the first moving blade and a second blade on the second moving blade can be meshed, and the double-moving-blade thread cutting device also comprises a first driving source, a second driving source, a first driving assembly and a second driving assembly, wherein the first driving source is connected with the first moving blade through the first driving assembly and drives the first moving blade to move, and the second driving source is connected with the second moving blade through the second driving assembly and drives the second moving blade to move.

Furthermore, the double-moving-blade thread cutting device of the sewing machine further comprises an auxiliary needle plate arranged on the main needle plate, a needle falling hole which is communicated up and down is formed in the auxiliary needle plate, and the auxiliary needle plate, a first blade on the first moving blade and a second blade on the second moving blade are sequentially arranged from top to bottom in the up-down direction; when the wire is cut, the first cutting edge on the first movable cutter and the second cutting edge on the second movable cutter can be occluded at the needle falling hole.

Furthermore, the double-moving-cutter thread cutting device of the sewing machine further comprises an auxiliary needle plate arranged on the main needle plate, and the auxiliary needle plate is provided with a needle falling hole which is communicated up and down; in an initial state, the distance between the first cutting edge on the first movable cutter and the needle falling hole on the auxiliary needle plate is 1.5-2.5 mm.

Further, in an initial state, the distance between the first cutting edge on the first movable cutter and the needle falling hole on the auxiliary needle plate is 2.2 mm.

Furthermore, when the thread is cut, the action of the second driving source is prior to the action of the first driving source, so that the movement of the second movable blade is prior to the movement of the first movable blade.

Further, the first driving source is provided with a movable first driving portion, the first driving assembly comprises a first connecting rod and a second connecting rod, one end of the first connecting rod is connected with one end of the first driving portion, the other end of the first connecting rod is hinged with one end of the second connecting rod, the other end of the second connecting rod is hinged with one end of the first movable knife, the first knife edge is arranged at the other end of the first movable knife, and the first movable knife is hinged to the main needle plate.

Further, the other end of the first driving part is fixedly connected with a cutter-out limiting block located outside the first driving source, and the cutter-out limiting block can be abutted to the shell of the first driving source.

Further, threaded connection has the back of the knife stopper that is located the outside of first driving source on the first connecting rod, the back of the knife stopper can be with the casing looks butt of first driving source.

Further, first drive assembly still includes to articulate in the piece that draws of second connecting rod, along the extension of first drive division moving direction reset extension spring and the mounting panel that is fixed in the casing of first driving source, reset extension spring's both ends link to each other with drawing piece and mounting panel respectively.

Furthermore, the second driving assembly comprises a rotating driving frame, a third connecting rod and a fourth connecting rod, the second moving blade and the rotating driving frame are hinged to the main needle plate, the rotating driving frame is driven by the second driving source to swing, the third connecting rod is fixed to the rotating driving frame, and two ends of the fourth connecting rod are respectively hinged to the third connecting rod and the second moving blade.

Furthermore, the rotary driving frame and the third connecting rod are fixed through fixing screws, waist-shaped adjusting holes are formed in the rotary driving frame, and the fixing screws penetrate through the waist-shaped adjusting holes.

Further, the second moves the sword and includes the part of dividing and the part of colluding that sets up relatively and connect the slide-wire portion between part of dividing and the part of colluding, the second cutting edge is close to the crossing department of part of dividing and slide-wire portion, the second moves the sword and has seted up on the up end towards the first sword and hold the wire casing, the one end that holds the wire casing extends to second cutting edge department, and the other end extends to the part of colluding.

As described above, the double-knife thread trimmer device of the sewing machine according to the present invention has the following advantageous effects:

in this application, drive respectively by two independent driving sources and move the sword motion with the second for first move the sword and the second move the sword and do not have linkage nature between the two, thereby have better adjustability and controllability, can realize the trimming effect of stub steadily.

Drawings

Fig. 1 to 3 are schematic structural views of a double-action-knife thread cutting device of a sewing machine in the present application at different viewing angles.

(wherein, FIG. 3 is a bottom view and is in an initial state.)

Fig. 4 is a schematic structural diagram of a first driving assembly in the present application.

Fig. 5 is a schematic structural diagram of a rotary driving frame in the present application.

Fig. 6 is a schematic structural view of the second moving blade in the present application.

Fig. 7 is a schematic diagram of the engagement of the first moving blade and the second moving blade during trimming.

Description of the element reference numerals

1 Main needle board

2 first moving knife

21 first blade

3 second moving knife

31 second blade

32 branching part

33 hook part

34 slide wire part

35 wire-containing groove

4 first driving source

5 pairs of needle plates

51-pin hole

6 first connecting rod

7 second connecting rod

8 cutter-discharging limiting block

9-knife-return limiting block

10 draw block

11 reset tension spring

12 mounting plate

13 rotating driving frame

131 waist-shaped adjusting hole

14 third connecting rod

15 fourth connecting rod

16 set screw

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

It should be understood that the structures, proportions, and dimensions shown in the drawings and described herein are for illustrative purposes only and are not intended to limit the scope of the present invention, which is defined by the claims, but rather by the claims. In addition, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description only and are not intended to limit the scope of the present invention, and changes or modifications of the relative relationship thereof may be made without substantial technical changes and modifications.

In the following examples, the directions are defined as follows: the axial direction of a main shaft in the sewing machine is defined as a left-right direction, and the direction of the main shaft facing a machine head is a left direction, and the direction of the main shaft facing a machine tail is a right direction. Thus, in the view shown in fig. 3, the left and right sides of the paper surface are the left and right directions, respectively, the back and front sides of the paper surface are the upper and lower directions, respectively, and the upper and lower sides of the paper surface are the rear and front directions, respectively.

The application provides a double-knife thread shearing device of a sewing machine, which is arranged in the sewing machine and is used for shearing off a thread after sewing is finished. As shown in fig. 1 to 3, the double-movable-blade thread cutting device of the sewing machine comprises a first movable blade 2 and a second movable blade 3 which are movably mounted on a main needle plate 1, a first driving source 4, a second driving source, a first driving assembly and a second driving assembly, wherein a first blade 21 on the first movable blade 2 and a second blade 31 on the second movable blade 3 can be meshed, the first driving source 4 is connected with the first movable blade 2 through the first driving assembly and drives the first movable blade 2 to move, and the second driving source is connected with the second movable blade 3 through the second driving assembly and drives the second movable blade 3 to move. In this application, drive respectively by two independent driving sources and move first sword 2 and the second and move sword 3 motion for first move the motion between sword 2 and the second move the sword 3 and do not have linkage nature, completely independent, and the action between the two can have certain chronogenesis, thereby make the double-action sword thread trimmer devices of sewing machine that this application relates to have better adjustability and controllability, can stably cut the line in ideal trimming position department, thereby realize the thread trimming effect of stub steadily.

As shown in fig. 1 to 3, the double-knife thread cutting device of the sewing machine further comprises an auxiliary needle plate 5 mounted on the main needle plate 1, the auxiliary needle plate 5 is provided with a needle falling hole 51 which is through up and down, and the auxiliary needle plate 5, the first knife edge 21 on the first movable knife 2 and the second knife edge 31 on the second movable knife 3 are sequentially arranged from top to bottom in the up-down direction; during trimming, the first blade 21 on the first movable blade 2 and the second blade 31 on the second movable blade 3 can be occluded at the needle falling hole 51, so that the ideal trimming position is the center of the needle falling hole 51 in the application, and the length of the thread end after trimming can be effectively shortened.

Further, the first movable blade 2 and the second movable blade 3 are both hinged to the main needle plate 1 by an axis screw extending up and down, so that the first movable blade 2 can rotate around the axis screw and has a fixed swing fulcrum O1, and the second movable blade 3 can also rotate around the axis screw and also has a fixed swing fulcrum O2. The first driving source 4 has a first driving part capable of moving left and right, so the first driving source 4 can be selected from a cylinder, an electromagnet, a linear motor and the like; the first driving source 4 is an electromagnet in the following embodiment.

The preferred structure of the first driving assembly connected between the first driving source 4 and the first moving blade 2 is: as shown in fig. 1 to 4, the first driving assembly includes a first connecting rod 6 and a second connecting rod 7, the left end of the first connecting rod 6 is connected to the right end of the first driving portion, the right end of the first connecting rod 6 is hinged to the left end of the second connecting rod 7, the right end of the second connecting rod 7 is hinged to the rear end of the first movable blade 2, and a first blade 21 is disposed at the front end of the first movable blade 2 and is connected to the middle position of the first movable blade 2 by a shaft screw for hinging the first movable blade 2 and the main needle plate 1. The first driving assembly further comprises a pulling block 10 hinged to the second connecting rod 7, a reset tension spring 11 extending left and right along the moving direction of the first driving portion, and a mounting plate 12 fixed to the right end of the shell in the first driving source 4, wherein the left end and the right end of the reset tension spring 11 are connected with the pulling block 10 and the mounting plate 12 respectively. When the first driving source 4 is powered on, the first driving portion moves rightwards, so that the first connecting rod 6, the second connecting rod 7 and the pulling block 10 are driven to move rightwards together, the return tension spring 11 is further stretched, and simultaneously the first movable knife 2 is driven to swing around a fixed swing fulcrum O1 through the first connecting rod 6 and the second connecting rod 7, the first movable knife 2 swings clockwise around a fixed swing fulcrum O1 in a view shown in fig. 3, and further the first knife edge 21 at the front end of the first movable knife 2 swings leftwards to the center position of the needle falling hole 51 on the sub needle plate 5. When the first driving source 4 is powered off, the pull block 10 is moved leftwards to be reset under the action of the reset tension spring 11, and then the first connecting rod 6, the second connecting rod 7, the first driving part and the first movable blade 2 are reset respectively. In addition, in the embodiment, the first link 6 is a step shaft, and the first link 6 and the second link 7, and the second link 7 and the pull block 10 are hinged through screw and nut assemblies.

Further, as shown in fig. 1 to 4, a cutter-discharging limiting block 8 located on the left side of the first driving source 4 is fixedly connected to the left end of the first driving portion, and the first driving portion and the cutter-discharging limiting block 8 can be connected by threads; in an initial state, a distance is reserved between the cutter-discharging limiting block 8 and the shell of the first driving source 4; when the first driving source 4 is powered on during trimming, the first driving part drives the cutter-out limiting block 8 to move rightwards together until the cutter-out limiting block 8 abuts against the shell of the first driving source 4. Therefore, the cutter-discharging limiting block 8 limits the cutter-discharging movement stroke of the first movable cutter 2, and the cutter-discharging movement stroke of the first movable cutter 2 can be adjusted by adjusting the distance between the cutter-discharging limiting block 8 and the shell of the first driving source 4 in the initial state; the cutter-discharging limiting block 8 is close to the shell of the first driving source 4, the distance between the cutter-discharging limiting block 8 and the shell of the first driving source 4 is smaller, the cutter-discharging motion stroke of the first movable cutter 2 is reduced, and the shearing line position is far away from the center of the needle falling hole 51 on the secondary needle plate 5; the cutter-discharging limiting block 8 is far away from the shell of the first driving source 4, the distance between the cutter-discharging limiting block 8 and the shell of the first driving source 4 is larger, the cutter-discharging motion stroke of the first movable cutter 2 is increased, and the position of a shear line is close to the center of the needle falling hole 51 on the auxiliary needle plate 5; the distance between the cutter-discharging limiting block 8 and the shell of the first driving source 4 in the initial state is adjusted to enable the line-cutting position to be located at the center of the needle-dropping hole 51, and the ideal line-cutting position is achieved. The first connecting rod 6 is in threaded connection with a knife return limiting block 9 positioned on the right side of the first driving source 4, and the knife return limiting block 9 can be a nut; in the initial state, when the first driving source 4 is in the power-off state, the knife return stopper 9 abuts against the housing of the first driving source 4. Therefore, in the process of trimming, when the first driving source 4 is powered on, the knife return limiting block 9 moves rightwards along with the first connecting rod 6 and is far away from the shell of the first driving source 4; after the first movable knife 2 and the second movable knife 3 cut off the sewing thread, the first driving source 4 is powered off, and the first connecting rod 6 is moved leftwards under the action of the reset tension spring 11 until the knife return limiting block 9 abuts against the shell of the first driving source 4. Therefore, the knife return limiting block 9 limits the knife return movement stroke of the first moving knife 2 and also determines the initial position of the first moving knife 2, the left and right positions of the knife return limiting block 9 on the first connecting rod 6 can be adjusted by rotating the knife return limiting block 9, and the distance between the knife return limiting block 9 and the shell of the first driving source 4 in the power-on state of the first driving source 4 is further adjusted, so that the knife return movement stroke of the first moving knife 2 is adjusted; the knife return limiting block 9 is close to the shell of the first driving source 4, and the knife return movement stroke of the first moving knife 2 is reduced; the knife return limiting block 9 is far away from the shell of the first driving source 4, and the knife return movement stroke of the first moving knife 2 is increased.

The preferred structure of the second driving assembly connected between the second driving source and the second moving blade 3 is: as shown in fig. 1 to 3, the second driving assembly includes a rotation driving frame 13, a third connecting rod 14 and a fourth connecting rod 15, the rotation driving frame 13 is hinged to the main needle plate 1 by a shaft screw extending up and down and has a fixed swing fulcrum O3, the rotation driving frame 13 is driven by the second driving source to swing, the third connecting rod 14 is fixed to the rotation driving frame 13, the right end of the fourth connecting rod 15 is hinged to the third connecting rod 14, the left end of the fourth connecting rod 15 is hinged to the middle part of the second movable knife 3 close to the rear part, and the shaft screw for hinging the second movable knife 3 and the main needle plate 1 is connected to the front end of the second movable knife 3. The second driving source can be a motor and can drive the rotary driving frame 13 to swing back and forth; when the second driving source drives the rotary driving frame 13 to swing clockwise, the rotary driving frame 13 drives the second movable blade 3 to swing counterclockwise through the third connecting rod 14 and the fourth connecting rod 15; when the second driving source drives the rotary driving frame 13 to swing counterclockwise, the rotary driving frame 13 drives the second movable blade 3 to swing clockwise through the third connecting rod 14 and the fourth connecting rod 15. The rotary driving frame 13 and the third connecting rod 14 are fixed through a fixing screw 16; as shown in fig. 5, a waist-shaped adjusting hole 131 is formed on the rotary driving frame 13; the fixing screw 16 is arranged in the waist-shaped adjusting hole 131 in a penetrating way; the position of the third connecting rod 14 fixed on the rotary driving frame 13 can be adjusted through the waist-shaped adjusting hole 131, so that the moving stroke of the second moving blade 3 can be adjusted.

In the application, the second moving blade 3 is used for branching, hooking and shearing lines; therefore, as shown in fig. 6, the second moving blade 3 includes a line dividing portion 32 and a line hooking portion 33 which are oppositely arranged on the left and right, and a line sliding portion 34 connected between the line dividing portion 32 and the line hooking portion 33, the line dividing portion 32 is a segment of arc which is concave towards the right, the line hooking portion 33 is a segment of arc which is concave towards the left, the line sliding portion 34 is a segment of arc which is convex towards the back, the junction of the line dividing portion 32 and the line sliding portion 34, and the junction of the line hooking portion 33 and the line sliding portion 34 are both formed with a tip, and the second blade 31 is adjacent to the intersection of the line dividing portion 32 and the line sliding portion 34; in addition, the second movable blade 3 is provided with a line accommodating groove 35 on the upper end surface facing the first movable blade 2, one end of the line accommodating groove 35 extends to the second blade 31, and the other end extends to the line hooking part 33.

Preferably, as shown in fig. 3, in the initial state, i.e. when the thread cutting action is not performed, the first blade 21 of the first movable blade 2 is not located at the needle falling hole 51 of the faller bar 5, but is slightly far away from the needle falling hole 51; in the embodiment, the distance between the first blade 21 on the first movable blade 2 and the needle dropping hole 51 on the auxiliary needle plate 5 is 1.5-2.5mm, and the preferred distance is 2.2 mm; the structure is beneficial to the second movable knife 3 to better complete the wire dividing action, avoids accidental cutting of the suture which does not need to be cut, and further ensures the wire dividing quality. Based on this, when cutting the thread, the action of the second driving source is prior to the action of the first driving source 4, so that the movement of the second movable blade 3 is prior to the movement of the first movable blade 2; therefore, when cutting the thread, the second driving source drives the second movable blade 3 to move first, the second movable blade 3 performs the thread splitting action first, and when the thread splitting action is completed or in the process of performing the thread splitting action, the first driving source 4 drives the first movable blade 2 to move, so that the first blade 21 on the first movable blade 2 moves to the central position of the needle dropping hole 51.

In summary, the operating principle of the double-knife thread trimming device of the sewing machine related to the present application is as follows:

in the initial state, as shown in fig. 3, the first blade 21 of the first moving blade 2 is slightly away from the needle dropping hole 51 and positioned on the right side of the needle dropping hole 51, the second blade 31 of the second moving blade 3 is not engaged with the first blade 21 of the first moving blade 2, and the second blade 31 is positioned on the right side of the first blade 21.

After the last stitch is sewn, the needle is turned back, the second driving source operates to drive the rotary driving frame 13 to swing clockwise around the fixed swing fulcrum O3, the rotary driving frame 13 drives the second movable knife 3 to swing anticlockwise around the fixed swing fulcrum O2 through the third connecting rod 14 and the fourth connecting rod 15, namely the second movable knife 3 swings at a certain angle towards the left front, the splitting part 32 on the second movable knife 3 completes splitting, the split part 32 does not need to split a suture line and swings towards the left front together with the splitting part 32, and the suture line to be split slides into the thread hooking part 33 along the sliding part 34.

After the branching action of the second movable knife 3 is finished or in the process of executing the branching action of the second movable knife 3, the first driving source 4 is electrified, the first movable knife 2 is driven to swing clockwise around the fixed swing fulcrum O1 through the first connecting rod 6 and the second connecting rod 7, and the first movable knife 2 rotates for a certain angle until the knife outlet limiting block 8 is abutted against the shell of the first driving source 4; at this time, the first blade 21 at the front end of the first movable blade 2 swings to the left to the center of the needle falling hole 51 on the sub needle plate 5.

The second driving source acts in the reverse direction to drive the rotary driving frame 13 to swing anticlockwise around the fixed swing fulcrum O3, so that the rotary driving frame 13 drives the second movable blade 3 to swing clockwise around the fixed swing fulcrum O2 through the third connecting rod 14 and the fourth connecting rod 15, namely the second movable blade 3 swings to a certain angle to the right rear side to perform a return stroke action, and a suture thread sliding into the hook part 33 in the return stroke process of the second movable blade 3 is gathered in the thread accommodating groove 35 on the upper end surface of the second movable blade 3; when the second blade 31 of the second movable blade 3 moves to the center of the needle drop hole 51 and engages with the first blade 21 of the first movable blade 2, the suture is cut off as shown in fig. 7, and the thread cutting action is realized. Therefore, the thread cutting position in the present application is located at the center of the needle dropping hole 51 on the faller bar 5, and after the thread cutting is completed, the second movable blade 3 is reset to the initial position.

After trimming, in the process of continuing the return stroke of the second movable blade 3 or after the second movable blade 3 is reset, the first driving source 4 is powered off, the first movable blade 2 is reset under the action of the reset tension spring 11, and the first connecting rod 6, the second connecting rod 7 and the pull block 10 are driven to reset respectively. And after the thread trimming action is finished, waiting for the next thread trimming command.

The double-knife thread cutting device of the sewing machine has the following advantages:

1. the first movable knife 2 and the second movable knife 3 are respectively driven by two independent driving sources, the actions of the driving sources can be controlled by electric control, and the action time of the first movable knife 2 and the action time of the second movable knife 3 can be more conveniently adjusted through programs in the electric control. Meanwhile, the initial position and the trimming position of the first movable knife 2 are respectively adjusted by the return limiting block and the knife-out limiting block 8, so that the adjustable knife has better adjustability in the aspects of electric control and machinery.

2. The thread cutting can be stably realized at the central position of the needle falling hole 51, the thread end after thread cutting is shorter, the length of the reserved thread on the needle hole in the next sewing is shortened, and the length of the initial thread end formed on the sewing material in the next sewing is reduced, so that the effects of shortening the initial thread end at the beginning of the sewing and shortening the residual thread end at the end of the sewing can be stably realized.

3. The whole structure is simple, the cost is low, and the occupied space is small.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims (11)

1. The utility model provides a double acting sword thread trimmer devices of sewing machine, moves sword (3) including all movably installing in first moving sword (2) and the second of main faller (1), first cutting edge (21) and the second on the second moves sword (3) on first moving sword (2) can interlock its characterized in that: the device is characterized by further comprising a first driving source (4), a second driving source, a first driving assembly and a second driving assembly, wherein the first driving source (4) is connected with the first movable knife (2) through the first driving assembly and drives the first movable knife (2) to move, and the second driving source is connected with the second movable knife (3) through the second driving assembly and drives the second movable knife (3) to move; the first driving source (4) is provided with a movable first driving portion, the first driving assembly comprises a first connecting rod (6) and a second connecting rod (7), one end of the first connecting rod (6) is connected with one end of the first driving portion, the other end of the first connecting rod is hinged to one end of the second connecting rod (7), the other end of the second connecting rod (7) is hinged to one end of the first movable knife (2), the other end of the first movable knife (2) is arranged on the first cutting edge (21), and the first movable knife (2) is hinged to the main needle plate (1).

2. Double-knife thread trimming apparatus for sewing machines according to claim 1, characterized in that: the needle plate structure is characterized by further comprising an auxiliary needle plate (5) arranged on the main needle plate (1), wherein a needle falling hole (51) which is communicated up and down is formed in the auxiliary needle plate (5), and the auxiliary needle plate (5), a first blade (21) on the first movable blade (2) and a second blade (31) on the second movable blade (3) are sequentially arranged from top to bottom in the up-down direction; when the yarn is cut, the first blade (21) on the first movable blade (2) and the second blade (31) on the second movable blade (3) can be meshed at the needle falling hole (51).

3. Double-knife thread trimming apparatus for sewing machines according to claim 1, characterized in that: the needle plate structure is characterized by further comprising an auxiliary needle plate (5) arranged on the main needle plate (1), wherein a needle falling hole (51) which is communicated up and down is formed in the auxiliary needle plate (5); in an initial state, the distance between the first blade (21) on the first movable blade (2) and the needle falling hole (51) on the auxiliary needle plate (5) is 1.5-2.5 mm.

4. A double-knife thread trimmer device for sewing machines according to claim 3, characterized in that: in an initial state, the distance between the first blade (21) on the first movable blade (2) and the needle falling hole (51) on the auxiliary needle plate (5) is 2.2 mm.

5. A double-knife thread trimmer device for sewing machines according to claim 3, characterized in that: when in thread cutting, the action of the second driving source is prior to the action of the first driving source (4), so that the movement of the second movable knife (3) is prior to the movement of the first movable knife (2).

6. Double-knife thread trimming apparatus for sewing machines according to claim 1, characterized in that: the other end fixedly connected with of first drive division is located the outside play sword stopper (8) of first driving source (4), play sword stopper (8) can be with the casing looks butt of first driving source (4).

7. Double-knife thread trimming apparatus for sewing machines according to claim 1, characterized in that: the first connecting rod (6) is connected with a knife return limiting block (9) which is positioned outside the first driving source (4) in a threaded mode, and the knife return limiting block (9) can be abutted to a shell of the first driving source (4).

8. Double-knife thread trimming apparatus for sewing machines according to claim 1, characterized in that: the first driving assembly further comprises a pulling block (10) hinged to the second connecting rod (7), a reset tension spring (11) extending along the moving direction of the first driving portion and a mounting plate (12) fixed to the shell of the first driving source (4), and two ends of the reset tension spring (11) are connected with the pulling block (10) and the mounting plate (12) respectively.

9. Double-knife thread trimming apparatus for sewing machines according to claim 1, characterized in that: the second driving assembly comprises a rotating driving frame (13), a third connecting rod (14) and a fourth connecting rod (15), the second movable knife (3) and the rotating driving frame (13) are hinged to the main needle plate (1), the rotating driving frame (13) is driven by the second driving source to swing, the third connecting rod (14) is fixed on the rotating driving frame (13), and two ends of the fourth connecting rod (15) are hinged to the third connecting rod (14) and the second movable knife (3) respectively.

10. A double-knife thread trimmer device for a sewing machine according to claim 9, wherein: the rotary driving frame (13) and the third connecting rod (14) are fixed through a fixing screw (16), a waist-shaped adjusting hole (131) is formed in the rotary driving frame (13), and the fixing screw (16) penetrates through the waist-shaped adjusting hole (131).

11. Double-knife thread trimming apparatus for sewing machines according to claim 1, characterized in that: the second moves sword (3) including the part of dividing (32) and the part of colluding (33) that set up relatively and connect slide wire portion (34) between part of dividing (32) and part of colluding (33), second cutting edge (31) are close to in the crossing department of part of dividing (32) and slide wire portion (34), second moves sword (3) and has seted up on the up end towards first moving sword (2) and hold line groove (35), the one end of holding line groove (35) extends to second cutting edge (31) department, and the other end extends to part of colluding (33).

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