Double-thread-pressing-plate type thread trimming mechanism of sewing machine

Abstract

The utility model belongs to the technical field of sewing machines. The thread trimming mechanism solves the problem that a thread trimming mechanism in the prior art is insufficient in working reliability. The sewing machine comprises a machine base, a needle plate with a needle falling hole and a rotating shuttle shaft arranged on the machine base, and the thread trimming mechanism comprises a first thread pressing piece, a movable cutter which is located below the needle plate and can swing up and down around the rotating shuttle shaft and a fixed cutter which is connected to the machine base and can be meshed with the movable cutter. The thread trimming structure further comprises a second thread pressing piece which is located below the needle plate and can swing up and down around the rotating shuttle shaft, the first thread pressing piece is hinged to the upper side face of the movable cutter, and when the movable cutter swings downwards and is meshed with the fixed cutter, the second thread pressing piece, the first thread pressing piece, the fixed cutter and the movable cutter abut against one another in sequence from top to bottom. The movable cutter is further provided with a reset spring acting on the first thread pressing piece, and the first thread pressing piece can overcome the effect of the elastic force of the reset spring and swing in the direction opposite to the fixed cutter under the action of external force. And thread trimming and sewing have high stability.

Description

TECHNICAL FIELD

[0001] The utility model belongs to sewing machine technical field relates to a sewing machine double pressure line board formula thread cutting mechanism. BACKGROUND

[0002] Thread cutting mechanism is the important component of sewing machine, for example, Chinese patent literature discloses a same circumference double knife bird nest thread cutting mechanism and sewing machine (application number: 202420143812.0), including main cutting line knife, and all rotatablely assembled in the sewing machine outer circumferential side of the rotating hook and the thread cutting knife after sewing, the thread cutting knife after sewing and the thread cutting knife before sewing are two independent thread cutting knives, and are distributed on the same circumferential surface along the rotation track;The thread cutting knife before sewing is provided with the thread cutting knife before sewing and the thread cutting knife before sewing, and the thread cutting knife before sewing is allowed to pass through the thread cutting knife before sewing, and the thread cutting knife before sewing can be engaged with the main cutting line knife;The thread cutting knife after sewing is provided with the thread cutting knife after sewing, and the thread cutting knife after sewing can be engaged with the main cutting line knife. Through the rotation of the thread cutting knife before sewing towards the main cutting line knife, the thread cutting knife before sewing realizes the bird nest prevention;Through the rotation of the thread cutting knife after sewing towards the main cutting line knife, the thread cutting knife after sewing realizes the automatic thread cutting after sewing.

[0003] The thread cutting mechanism of the sewing machine has the following disadvantages in the use process: when sewing, the thread cutting knife before sewing is rotated towards the main cutting line knife, and the thread cutting knife before sewing is hooked on the thread head of the needle on one side, and the thread head is cut off, but when the thread cutting mechanism cuts the thread, the residual thread head is short, and when the thread is collected upwards, the short thread head is easily taken out of the needle hole by the thread tension lever, causing the sewing failure. SUMMARY

[0004] The utility model aims at the above -mentioned problem existing in prior art, and proposes a sewing machine double pressure line board formula thread cutting mechanism.The utility model solves the technical problem of the insufficient work reliability of the prior art thread cutting mechanism.

[0005] The utility model discloses the purpose can be realized through the following technical scheme:

[0006] A sewing machine double pressure line board formula thread cutting mechanism, the sewing machine includes a needle plate with a needle hole and a rotating hook shaft arranged on the machine base, the thread cutting mechanism includes a first pressure line piece, a movable cutter located below the needle plate and capable of swinging up and down around the rotating hook shaft, and a fixed cutter connected to the machine base and capable of engaging with the movable cutter, characterized in that the thread cutting mechanism further includes a second pressure line piece located below the needle plate and capable of swinging up and down around the rotating hook shaft, the first pressure line piece is hinged to the upper side of the movable cutter, when the movable cutter swings downward and engages with the fixed cutter, the second pressure line piece, the first pressure line piece, the fixed cutter and the movable cutter are sequentially arranged in a vertical direction, and the movable cutter is further provided with a return spring acting on the first pressure line piece, under the action of external force, the first pressure line piece can overcome the elastic force of the return spring and swing in the direction away from the fixed cutter.

[0007] In the thread cutting structure, when the first needle sewing is completed, the thread on the needle is located in the thread hooking groove of the moving knife. At this time, the moving knife is swung downward to approach the fixed knife and the second thread pressing piece until the blade edge of the moving knife and the blade edge of the fixed knife are engaged to cut the sewing thread, and at the same time, the second thread pressing piece, the first thread pressing piece, the fixed knife and the moving knife are sequentially arranged from top to bottom. The second thread pressing piece and the first thread pressing piece and the first thread pressing piece and the fixed knife press the residual thread at the same time, forming a double thread pressing structure to better position the residual thread. Then, the second thread pressing piece swings upward around the rotating shuttle shaft to push the first thread pressing piece to swing toward the needle hole direction, and cooperates with the thread lifting lever to wind the thread upward, so that the residual thread on the fabric is as short as possible, realizes better bird nest prevention effect, improves the beauty of sewing, and because the residual thread is pressed by the second thread pressing plate, it will not be taken out of the needle hole by the thread lifting lever when winding, so that the thread cutting and sewing have high stability, thereby solving the problem of insufficient working reliability of the existing thread cutting mechanism.

[0008] In the above-mentioned double thread pressing plate type thread cutting mechanism of the sewing machine, the thread cutting structure further comprises a knife seat arranged on the machine base and capable of swinging around the rotating shuttle shaft, the second thread pressing piece is fixedly connected to the knife seat, and the driving source capable of driving the knife seat to swing is connected to the knife seat. After the sewing thread is cut, the driving source can also drive the second thread pressing piece to swing upward, so that the second thread pressing piece swings upward around the rotating shuttle shaft to push the first thread pressing piece to swing toward the needle hole direction and as close to the needle hole as possible, and cooperates with the thread lifting lever to wind the thread upward, so that the residual thread on the fabric is as short as possible, realizes better bird nest prevention effect, improves the beauty of sewing, and because the residual thread is pressed by the second thread pressing plate, it will not be taken out of the needle hole by the thread lifting lever when winding, so that the thread cutting and sewing have high stability, thereby solving the problem of insufficient working reliability of the existing thread cutting mechanism.

[0009] In the double-presser-foot type thread trimming mechanism of the sewing machine, the second presser foot is a strip-shaped metal piece, and the second presser foot includes a flat section parallel to the hook shaft and an arc-shaped section protruding from the flat section to the side, and the curvature of the arc-shaped section matches the curvature of the upper surface of the first presser foot. The flat section is fixed to the cutter holder, and the end of the arc-shaped section away from the flat section is a second presser foot end abutting against the first presser foot. The second presser foot is swingably installed, the first presser foot is installed on the moving cutter and moves with the moving cutter, and the second presser foot can swing upward to push the first presser foot to swing toward the needle hole and be as close to the needle hole as possible. In combination with the thread take-up lever, the residual thread on the fabric is as short as possible, better bird nest prevention effect is achieved, the appearance of sewing is improved, and the residual thread is not taken out of the needle hole by the thread take-up lever during thread take-up because the residual thread is pressed by the second presser foot, so that the thread trimming and sewing have high stability, and the working reliability of the thread trimming mechanism is improved.

[0010] In the double-presser-foot type thread trimming mechanism of the sewing machine, the first presser foot is in a strip-shaped piece, one end of the first presser foot is hinged to the moving cutter, and the other end is a first presser foot end. The moving cutter has a limiting protrusion, and under the elastic action of the return spring, the side edge of the first presser foot close to the fixed cutter can abut against the limiting protrusion, and the lower side of the first presser foot end close to the fixed cutter is located above the blade edge of the moving cutter. When the first presser foot is not subjected to the thrust of the fixed cutter and the second presser foot, the first presser foot can always abut against the limiting protrusion under the action of the return spring, the first presser foot is positioned, and the lower side of the first presser foot end close to the fixed cutter is located above the blade edge of the moving cutter. When the moving cutter swings to the thread trimming position, the fixed cutter can abut against the lower side of the first presser foot, so that the thread is stably pressed.

[0011] In the double-presser-foot type thread trimming mechanism of the sewing machine, the lower side of the first presser foot end close to the fixed cutter and the upper side of the moving cutter have an avoiding gap, and when the moving cutter swings downward, the end of the fixed cutter with the blade edge can enter the avoiding gap and abut against the lower side of the first presser foot end. When the moving cutter swings to the thread trimming position, the thread trimming end of the fixed cutter can enter the avoiding gap and abut against the lower side of the first presser foot end, so that the thread pressing effect is improved, the thread loosening caused by thread pressing failure is avoided, and the working reliability of the thread trimming mechanism is improved.

[0012] In the double-thread-pressing-plate type thread trimming mechanism of the sewing machine, the upper side of the first-thread-pressing end near the fixed knife is a first pushing inclined surface, which gradually approaches the lower side of the second-thread-pressing plate from one end to the other end of the first pushing inclined surface; the lower side of the first-thread-pressing end near the fixed knife is a second pushing inclined surface, which gradually approaches the upper side of the moving knife from one end to the other end of the second pushing inclined surface. When the first-thread-pressing plate swings toward the fixed knife, the second pushing inclined surface enables the fixed knife to smoothly push the first-thread-pressing plate to move together; when the first-thread-pressing plate swings toward the needle hole, the first pushing inclined surface enables the second-thread-pressing plate to smoothly push the first-thread-pressing plate to move together, and the thread is stably pressed by the second-thread-pressing plate and the first-thread-pressing plate during the movement, so that when the first-thread-pressing plate swings toward the needle hole, the thread is reeled up by the thread guide, the residual thread on the cloth is as short as possible, better bird nest prevention effect is achieved, and the appearance of sewing is improved. At the same time, the residual thread is pressed by the second-thread-pressing plate and cannot be taken out of the needle hole by the thread guide during the reeling, so that the thread trimming and sewing have higher stability and shorter reserved thread, and the problem of insufficient working reliability of the existing thread trimming mechanism is solved.

[0013] In the double-thread-pressing-plate type thread trimming mechanism of the sewing machine, a mounting hole is arranged on the moving knife, a connecting hole is arranged on one end of the first-thread-pressing plate, a hinge element connected with the mounting hole is arranged in the connecting hole, and the first-thread-pressing plate can rotate around the hinge element. The hinge element can be a bolt which is threadedly connected with the mounting hole and the connecting hole, or the hinge element can be a pin which is riveted with the mounting hole and the connecting hole. Of course, the structure of the hinge element can also be other structures except the bolt and the pin, as long as the hinge element can be installed on the first-thread-pressing plate.

[0014] In the double-thread-pressing-plate type thread trimming mechanism of the sewing machine, the reset spring is a torsion spring sleeved on the hinge element, one end of the torsion spring is fixed on the moving knife, and the other end of the torsion spring is fixed on the first-thread-pressing plate. When the first-thread-pressing plate is not subjected to the pushing force of the fixed knife, the first-thread-pressing plate is always positioned on the limiting protrusion of the moving knife by the action of the reset spring, the lower side of the first-thread-pressing end near the fixed knife of the first-thread-pressing plate is located above the blade of the moving knife, and the upper side of the fixed knife can smoothly abut against the lower side of the first-thread-pressing plate when the moving knife swings toward the fixed knife to the thread trimming position, so that the thread is stably pressed.

[0015] In the double-thread-pressing-plate type thread cutting mechanism of the sewing machine, the reset spring is a tension spring arranged on the upper side of the moving knife, and the two ends of the tension spring are connected to the moving knife and the first thread pressing plate respectively.

[0016] In the double-thread-pressing-plate type thread cutting mechanism of the sewing machine, the reset spring is a spring sheet arranged on the upper side of the moving knife, and the two ends of the spring sheet are connected to the moving knife and the first thread pressing plate respectively.

[0017] Compared with the prior art, the double-thread-pressing-plate type thread cutting mechanism of the sewing machine has the advantages that: the double-thread-pressing-plate type thread cutting mechanism of the sewing machine is provided with a second thread pressing plate, so that a double-thread-pressing structure is formed between the second thread pressing plate and the first thread pressing plate and between the first thread pressing plate and the fixed knife when cutting the thread, the second thread pressing plate can be swung upward around the rotating hook shaft to push the first thread pressing plate to swing toward the drop needle hole and to be as close to the drop needle hole as possible, and the thread on the cloth can be as short as possible by cooperating with the thread collecting lever, so that a better bird nest prevention effect is achieved, the appearance of the sewing is improved, and the residual thread on the cloth will not be taken out of the needle hole by the thread collecting lever when the thread is collected, so that the thread cutting and the sewing have high stability, and the problem of insufficient working reliability of the existing thread cutting mechanism is solved. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a partial structure schematic view of the double-thread-pressing-plate type thread cutting mechanism of the sewing machine in Example One.

[0019] Figure 2 is Figure 1 a partial enlarged view of A in

[0020] Figure 3 is a partial structure schematic view of the double-thread-pressing-plate type thread cutting mechanism of the sewing machine in Example One.

[0021] Figure 4 is a structure schematic view of the first thread pressing plate, the moving knife, the fixed knife and the second thread pressing plate of the double-thread-pressing-plate type thread cutting mechanism of the sewing machine in Example One.

[0022] Figure 5 is Figure 4A cross-sectional view at A-A.

[0023] Figure 6 is Figure 5 A local enlarged view at B.

[0024] Figure 7 is an exploded view of the moving knife, the presser foot, the reset spring and the hinge part of the double presser foot type thread trimming mechanism of the sewing machine in Example One.

[0025] Figure 8 is a perspective structural schematic view of the first presser foot of the double presser foot type thread trimming mechanism of the sewing machine in Example One.

[0026] Figure 9 is a local perspective structural schematic view of the second presser foot of the double presser foot type thread trimming mechanism of the sewing machine in Example One.

[0027] In the figure, 1 is a machine base; 2 is a needle plate; 2a is a needle drop hole; 3 is a first presser foot; 3a is a first presser foot end; 3a1 is a first pushing inclined surface; 3a2 is a second pushing inclined surface; 3b is a connecting hole; 4 is a moving knife; 4a is a limiting protrusion; 4b is a mounting hole; 4c is a thread hooking groove; 5 is a fixed knife; 6 is a second presser foot; 6a is a flat section; 6b is an arc section; 6b1 is a second presser foot end; 7 is a reset spring; 8 is a knife seat; 9 is an avoiding gap; 10 is a hinge part; 11 is a rotating hook; and 12 is a needle. DETAILED DESCRIPTION

[0028] The following is a specific embodiment of the present application and further describes the technical solution of the present application in combination with the accompanying drawings, but the present application is not limited to these embodiments.

[0029] Example One

[0030] A double presser foot type thread trimming mechanism of a sewing machine, referring to Figures 1-9 , the sewing machine comprises a machine base 1, a needle plate 2 with a needle drop hole 2a and a rotating hook shaft arranged on the machine base 1, the thread trimming mechanism comprises a first presser foot 3, a moving knife 4 arranged below the needle plate 2 and capable of swinging up and down around the rotating hook shaft and a fixed knife 5 connected to the machine base 1 and capable of engaging with the moving knife 4, the thread trimming mechanism further comprises a second presser foot 6 arranged below the needle plate 2 and capable of swinging up and down around the rotating hook shaft, the first presser foot 3 is hinged to the upper side of the moving knife 4, when the moving knife 4 swings downward and engages with the fixed knife 5, the second presser foot 6, the first presser foot 3, the fixed knife 5 and the moving knife 4 are sequentially arranged in a top-to-bottom manner, and the moving knife 4 is further provided with a reset spring 7 acting on the first presser foot 3, under the action of external force, the first presser foot 3 can overcome the elastic force of the reset spring 7 and swing in a direction away from the fixed knife 5.

[0031] Referring to Figures 1-9The second pressure thread sheet 6 is fixedly connected to the cutter holder 8, and a driving source for driving the cutter holder 8 to swing is connected to the cutter holder 8. Specifically, the second pressure thread sheet 6 is a strip-shaped metal sheet which is bent to form a flat section 6a parallel to the rotating hook shaft and an arc section 6b protruding from the flat section 6a to one side. The arc section 6b has an arc which matches the arc of the upper surface of the first pressure thread sheet 3. The flat section 6a is fixedly connected to the cutter holder 8, and the arc section 6b has an end which is away from the flat section 6a and which abuts against the first pressure thread sheet 3.

[0032] Referring to Figures 1-8 The first pressure thread sheet 3 is strip-shaped, and one end of the first pressure thread sheet 3 is hingedly connected to the moving cutter 4, and the other end is a first pressure thread end 3a. The moving cutter 4 has a limiting protrusion 4a, and under the elastic action of the reset spring 7, the side edge of the first pressure thread sheet 3 close to the fixed cutter 5 can abut against the limiting protrusion 4a, and the lower side of the first pressure thread end 3a close to the fixed cutter 5 is located above the blade edge of the moving cutter 4.

[0033] Referring to Figures 1-8 The lower side of the first pressure thread end 3a close to the fixed cutter 5 has a clearance 9 with the upper side of the moving cutter 4, and when the moving cutter 4 swings downward, the end of the fixed cutter 5 having the blade edge can enter the clearance 9 and abut against the lower side of the first pressure thread end 3a.

[0034] Referring to Figures 1-9 The upper side of the first pressure thread end 3a close to the fixed cutter 5 is a first pushing inclined surface 3a1 which gradually approaches the lower side of the second pressure thread sheet 6 from one end close to the second pressure thread sheet 6 to the other end. The lower side of the first pressure thread end 3a close to the fixed cutter 5 is a second pushing inclined surface 3a2 which gradually approaches the upper side of the moving cutter 4 from one end close to the fixed cutter 5 to the other end.

[0035] Referring to Figures 1-7 The moving cutter 4 is provided with a mounting hole 4b, and one end of the first pressure thread sheet 3 is provided with a connecting hole 3b. A hinge 10 is arranged in the connecting hole 3b and connected to the mounting hole 4b. The first pressure thread sheet 3 can rotate around the hinge 10.

[0036] Referring to Figure 7 The reset spring 7 is a torsion spring which is sleeved on the hinge 10. One end of the torsion spring is fixed to the moving cutter 4, and the other end of the torsion spring is fixed to the first pressure thread sheet 3.

[0037] The working principle of the double-pressure-thread-plate type thread trimming mechanism of the sewing machine is described below:

[0038] Before the sewing machine starts to sew the first needle, the moving knife 4 moves upward, so that the thread hooking groove 4c on the moving knife 4 moves away from one end of the moving knife edge to be right below the needle 12, or during the process that the needle 12 of the sewing machine moves downward to start to sew the first needle, the moving knife 4 moves simultaneously, so that the thread hooking groove 4c on the moving knife 4 moves away from one end of the moving knife edge to be right below the needle 12.

[0039] When the sewing machine sews the first needle, the needle 12 passes through the thread hooking groove 4c on the moving knife 4 with the thread, then the needle 12 moves upward, when the needle 12 moves to above the needle plate 2, the moving knife 4 swings downward with the first thread pressing piece 3 to be close to the fixed knife 5, until the moving knife edge and the fixed knife edge are engaged to cut the thread, at this time, the second thread pressing piece 6, the first thread pressing piece 3, the fixed knife 5 and the moving knife 4 are sequentially arranged from top to bottom, at the same time, the fixed knife 5 and the first thread pressing piece 3 and the second thread pressing piece 6 and the first thread pressing piece 3 simultaneously press the residual thread, forming a double thread pressing structure to better position the residual thread.

[0040] Then, the second thread pressing piece 6 swings upward around the rotating hook shaft to push the first thread pressing piece 3 to swing toward the direction of the needle drop hole 2a, and the thread is collected upward by the thread tensioner, so that the residual thread on the cloth is as short as possible, better bird nest prevention effect is achieved, the appearance of sewing is improved, and because the residual thread is pressed by the second thread pressing piece 6, the thread will not be taken out of the needle hole by the thread tensioner during thread collection, so that the thread cutting and sewing have high stability, thereby solving the problem of insufficient working reliability of the existing thread cutting mechanism, Figure 6 In the figure, the thicker line indicates the cut thread.

[0041] Embodiment two

[0042] The structure and principle of the embodiment are basically the same as those of embodiment one, and the difference lies in that the reset spring 7 is a tension spring arranged on the upper side of the moving knife 4, and the two ends of the tension spring are connected to the moving knife 4 and the first thread pressing piece 3 respectively.

[0043] Embodiment three

[0044] The structure and principle of the embodiment are basically the same as those of embodiment one, and the difference lies in that the reset spring 7 is a spring leaf arranged on the upper side of the moving knife 4, and the two ends of the spring leaf are connected to the moving knife 4 and the first thread pressing piece 3 respectively.

[0045] The specific embodiments described in the present document are merely illustrative of the spirit of the present document. Those skilled in the art to which the present document belongs can make various modifications or supplements to the described specific embodiments or replace them with similar ways, but will not deviate from the spirit of the present document or exceed the scope defined by the appended claims.

Claims

1. A double presser foot type thread trimming mechanism of a sewing machine, the sewing machine comprising a machine base (1), a needle plate (2) having a needle drop hole (2a), and a rotating hook shaft provided on the machine base (1), the thread trimming mechanism comprising a first presser foot (3), a moving blade (4) positioned below the needle plate (2) and capable of swinging up and down about the rotating hook shaft, and a fixed blade (5) connected to the machine base (1) and capable of engaging with the moving blade (4), characterized in that, The thread shearing structure further comprises a second thread pressing piece (6) which is arranged below the needle plate (2) and can swing up and down around the rotating hook shaft, the first thread pressing piece (3) is hinged on the upper side of the moving cutter (4), when the moving cutter (4) swings downward and engages with the fixed cutter (5), the second thread pressing piece (6), the first thread pressing piece (3), the fixed cutter (5) and the moving cutter (4) are sequentially arranged from top to bottom, and the moving cutter (4) is further provided with a reset spring (7) which acts on the first thread pressing piece (3), under the action of external force, the first thread pressing piece (3) can overcome the elastic force of the reset spring (7) and swing in the direction away from the fixed cutter (5).

2. A twin threader plate thread trimming mechanism for a sewing machine according to claim 1, wherein The thread shearing structure further comprises a cutter holder (8) which is arranged on the machine base (1) and can swing around the rotating hook shaft, the second thread pressing piece (6) is fixedly connected to the cutter holder (8), and the cutter holder (8) is connected to a driving source which can drive the cutter holder (8) to swing.

3. A twin thread presser foot thread trimming mechanism for a sewing machine according to claim 2 wherein, The second thread pressing piece (6) is a strip-shaped metal piece which is bent, the second thread pressing piece (6) comprises a flat section (6a) which is arranged in parallel with the rotating hook shaft and an arc-shaped section (6b) which protrudes to the side relative to the flat section (6a), the curvature of the arc-shaped section (6b) matches the curvature of the upper surface of the first thread pressing piece (3), the flat section (6a) is fixedly connected to the cutter holder (8), and one end of the arc-shaped section (6b) which is away from the flat section (6a) is a second thread pressing end (6b1) which abuts against the first thread pressing piece (3).

4. A twin thread plate cutting mechanism for a sewing machine according to claim 1 or 2 or 3, wherein The first thread pressing piece (3) is in the shape of a strip-shaped piece, one end of the first thread pressing piece (3) is hinged to the moving cutter (4), and the other end is a first thread pressing end (3a), the moving cutter (4) is provided with a limiting protrusion (4a), under the elastic action of the reset spring (7), the side edge of the first thread pressing piece (3) which is close to the fixed cutter (5) can abut against the limiting protrusion (4a), and the lower side of the first thread pressing end (3a) which is close to the fixed cutter (5) is located above the cutting edge of the moving cutter (4).

5. A twin threader plate thread trimmer mechanism for a sewing machine as defined in claim 4 wherein, The lower side of the first thread pressing end (3a) which is close to the fixed cutter (5) has a clearance (9) with the upper side of the moving cutter (4), when the moving cutter (4) swings downward, the end of the fixed cutter (5) which has a cutting edge can enter the clearance (9) and make the upper side of the end abut against the lower side of the first thread pressing end (3a).

6. A twin threader plate thread trimmer mechanism for a sewing machine as defined in claim 5 wherein, The upper side of the first thread pressing end (3a) which is close to the fixed cutter (5) is a first pushing inclined surface (3a1), the first pushing inclined surface (3a1) gradually approaches the lower side of the second thread pressing piece (6) from one end close to the second thread pressing piece (6) to the other end, the lower side of the first thread pressing end (3a) which is close to the fixed cutter (5) is a second pushing inclined surface (3a2), the second pushing inclined surface (3a2) gradually approaches the upper side of the moving cutter (4) from one end close to the fixed cutter (5) to the other end.

7. A twin thread presser foot thread trimming mechanism for a sewing machine as defined in claim 4 wherein, The moving cutter (4) is provided with a mounting hole (4b), one end of the first thread pressing piece (3) is provided with a connecting hole (3b), a hinge piece (10) which is connected to the mounting hole (4b) is arranged in the connecting hole (3b), and the first thread pressing piece (3) can rotate around the hinge piece (10).

8. A twin threader plate thread trimmer mechanism for a sewing machine as defined in claim 7, wherein The reset spring (7) is a torsion spring sleeved on the hinge (10), one end of the torsion spring is fixed on the moving blade (4), and the other end of the torsion spring is fixed on the first line pressing sheet (3).

9. A twin threader plate thread trimmer mechanism for a sewing machine as defined in claim 7 wherein, The reset spring (7) is a tension spring arranged on the upper side surface of the moving blade (4), and the two ends of the tension spring are connected to the moving blade (4) and the first line pressing sheet (3) respectively.

10. The double threader thread trimmer mechanism of claim 7 wherein, The reset spring (7) is a spring sheet arranged on the upper side surface of the moving blade (4), and the two ends of the spring sheet are connected to the moving blade (4) and the first line pressing sheet (3) respectively.

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