CN216040164U - Upper thread cutting device of sewing machine - Google Patents

Abstract

The utility model provides a surface thread cutting device of a sewing machine, and belongs to the technical field of auxiliary equipment of sewing machines. This facial line cutting device includes the mounting bracket, is fixed with the driving source on the mounting bracket, and the driving source has the output shaft, is connected with on the output shaft and dials line hook frame one and dial line hook frame two, dials line hook frame one and dials line hook two below of line hook frame two and is connected with respectively and dials line hook one and dials line hook two, still is provided with on the mounting bracket and is used for carrying out the line ball subassembly one and the line ball subassembly two that compress tightly to the facial line respectively. The upper thread cutting device can simultaneously hook and clamp threads on two needles, so that subsequent thread cutting operation is smoothly carried out, the convenience of operation is improved, and thread separation and thread residue on sewing materials are prevented when a sewing machine is started.

Description

Upper thread cutting device of sewing machine

Technical Field

The utility model belongs to the technical field of auxiliary equipment of sewing machines, and relates to an upper thread cutting device of a sewing machine.

Background

A sewing machine is a machine that uses one or more sewing threads to form one or more stitches in a material to be sewn, interweaving or stitching one or more layers of the material. The sewing machine can sew fabrics such as cotton, hemp, silk, wool, artificial fiber, etc., and products such as leather, plastics, etc. The computer double-needle machine comprises a needle plate, a machine needle above the needle plate and a thread cutting mechanism arranged below the needle plate and used for cutting threads. The upper thread is threaded on the machine needle, the bottom thread is arranged below the needle plate, and the machine needle can move back and forth on the needle plate. The computer double-needle machine drives the upper thread to shuttle up and down on the fabric through the machine needle and to be matched with the bottom thread below the fabric to sew the fabric. When the computer double-needle machine finishes sewing, the bottom thread and the surface thread below the needle plate are automatically cut off through the thread cutting mechanism.

The existing computer double-needle machine has the defects that after last sewing is finished and a bottom thread and a surface thread are cut off, the head part of the surface thread is remained under a needle plate for a long time as the surface thread is cut off under the needle plate. When the operation of the next sewing procedure is started, the double-needle machine moves rapidly, so that the upper thread end is accumulated below the fabric during sewing, and a thread ball is formed on the fabric, thereby greatly influencing the product quality.

To avoid the appearance of coils, a coil-proof structure is generally required. The prior flat sewing machine in the industry has a bird's nest prevention structure, the structure clamps the thread end through a thread clamping device, a blade is arranged on a presser foot, and the thread end is cut off on the edge of the presser foot through the thread clamping device and the pulling of sewing materials during the seam starting, so that the thread group problem is solved.

However, the above structure cannot be well applied to a double-needle type, especially in the aspects of thread hooking and clamping, threads on two needles cannot be hooked and clamped simultaneously according to the requirements of different needle positions, and the cut thread ends cannot be cleaned quickly in time, so that the reuse of the thread-block-preventing structure and the cleanliness of sewing materials are affected, and the double-needle type cannot be adapted to different needle position models.

Disclosure of Invention

The utility model provides an upper thread cutting device of a sewing machine aiming at the problems in the prior art, and the technical problems to be solved by the utility model are as follows: how to simultaneously hook and clamp the threads on two needles.

The purpose of the utility model can be realized by the following technical scheme:

the utility model provides a sewing machine's facial line cutting device, facial line cutting device includes the mounting bracket, be fixed with the driving source on the mounting bracket, the driving source has the output shaft, a serial communication port, be connected with on the output shaft and dial a line hook frame one and dial a line hook frame two, dial a line hook frame one and dial the below of line hook frame two and be connected with respectively and dial a line hook and dial line hook two, still be provided with on the mounting bracket and be used for carrying out the line ball subassembly one and the line ball subassembly two that compress tightly to the facial line respectively.

The working principle is as follows: in the upper thread cutting device, an installation rack, a driving source, a first wire shifting hook frame, a second wire shifting hook frame, a first wire pressing component, a second wire pressing component and the like form an upper thread shifting mechanism, after thread cutting is completed, a machine needle is located at an upper needle stop position, the driving source receives an instruction at the moment, the driving source drives an output shaft to axially move up and down, the output shaft drives the first wire shifting hook frame and the second wire shifting hook frame to simultaneously move up or down, the first wire shifting hook and the second wire shifting hook respectively hook a first wire on the needle and then simultaneously move up or down, and when the first wire shifting hook and the second wire shifting hook respectively pull the hooked wires to the first wire pressing component and the second wire pressing component, the first wire pressing component and the second wire pressing component respectively clamp the corresponding wires. The upper thread cutting device can simultaneously hook and clamp threads on two needles, so that subsequent thread cutting operation is smoothly carried out, the convenience of operation is improved, and thread separation and thread residue on sewing materials are prevented when a sewing machine is started. When the sewing is performed next time, the head of the upper thread is clamped by the first thread pressing assembly and the second thread pressing assembly, and the upper thread is cut off by the blade below the presser foot assembly due to the effect of certain tension.

The driving source may be a linear motor, an oil cylinder, an air cylinder, etc.

In the above-mentioned upper thread cutting device of sewing machine, the upper thread cutting device includes still that it puts up the line distance adjusting part to dial, it includes movable plate one and movable plate two to dial the line distance adjusting part, be fixed with support frame one and support frame two on movable plate one and the movable plate two respectively, it connects respectively to dial line hook frame one and dial line hook frame two on support frame one and the support frame two, movable plate one and two sliding connection of movable plate are in just can make on the mounting bracket support frame one and support frame two are drawn close together or are separated.

The first support frame and the second support frame are close to or separate from each other by sliding the first movable plate and the second movable plate, the first thread shifting hook frame and the second thread shifting hook frame are close to or separate from each other at the same time, the distance between the first thread shifting hook and the second thread shifting hook can be adjusted according to different double-needle pitches, and the adaptability is good.

In foretell sewing machine's surface wire cutting device, dial line distance adjusting part still includes bolt one and spacing apron, the bottom of spacing apron has the dog, the bottom of movable plate one and two the two of movable plate supports and leans on the dog, and spout one and spout two have been seted up on movable plate one and the movable plate two respectively, spout one and spout intercrossing, bar groove one and bar groove two have been seted up on spacing apron and the mounting bracket respectively, bar groove one and bar groove two extend along vertical direction, bolt one is worn to establish on bar groove one, spout two and bar groove two, threaded connection has nut one on the tip of bolt one, nut one with the mounting bracket offsets and leans on.

In the structure, a first bolt is fixed on the mounting frame in a threaded fastening connection mode with a first nut, the first nut is loosened, the bottoms of a first moving plate and a second moving plate abut against a stop block when the first bolt is moved upwards, the first moving plate and the second moving plate do not move in the vertical direction and move oppositely in the horizontal direction, so that a first wire shifting hook frame and a second wire shifting hook frame are close to each other, and the first wire shifting hook and the second wire shifting hook can be indirectly adjusted to be small; on the contrary, the bolt is moved downwards for a while, so that the first wire shifting hook frame is separated from the second wire shifting hook frame, and the distance between the first wire shifting hook and the second wire shifting hook can be increased.

In foretell sewing machine's surface wire cutting device, be fixed with respectively on support frame one and the support frame two along the guide bar one that vertical direction extends, dial on the line hook frame one and dial line hook frame two respectively sliding connection on the guide bar one that corresponds, be fixed with the driving source on the output shaft and connect, be fixed with on the driving source connects along the guide bar two that the horizontal direction extends, dial line hook frame one and dial two sliding connection of line hook frame on the guide bar is two.

The first guide rod and the second guide rod play a role in guiding, and when the output shaft of the driving source drives the first wire shifting hook frame and the second wire shifting hook frame to move up and down, or the first moving plate and the second moving plate respectively drive the first wire shifting hook frame and the second wire shifting hook frame to move horizontally, the stability during moving can be improved.

As an embodiment, a third nut can be screwed on the output shaft, and the third nut can press against the driving source joint.

In the upper thread cutting device of the sewing machine, the first thread pressing plate bracket and the second thread pressing plate bracket are respectively fixed on the first support frame and the second support frame, and the first thread pressing assembly and the second thread pressing assembly are respectively fixed on the first thread pressing plate bracket and the second thread pressing plate bracket.

In the above-mentioned upper thread cutting device of sewing machine, first line ball subassembly includes line ball piece support spring and face line pressure line spring, the interior tip of line ball piece support spring is fixed and the two is fixed with the inner of face line pressure line spring on the line ball support, the outer tip of line ball piece support spring has the kink, the kink supports with the outer tip of face line pressure line spring and leans on, and the line ball piece supports the middle part of the two of spring and face line pressure line spring and leans on and fix on the line ball support.

In the structure, the line pressing piece supporting spring and the surface line pressing spring both have elasticity, the bending part of the line pressing piece supporting spring is abutted against the outer end part of the surface line pressing spring, and the bending part and the outer end part of the surface line pressing spring clamp a line hooked by a line pulling hook together.

As an embodiment, the second wire pressing assembly has the same structure as the first wire pressing assembly, and also includes a wire pressing sheet supporting spring and a surface wire pressing spring.

In the upper thread cutting device of the sewing machine, the middle parts of the thread pressing piece supporting spring and the upper thread pressing spring are fixed on the first thread pressing plate support through the second bolt, the second bolt is sleeved with the rubber ring and the gasket, the rubber ring abuts against the upper thread pressing spring, the second bolt is in threaded connection with the second nut, and the second nut abuts against the rubber ring.

In the structure, the second bolt and the second nut are fastened through threads, the middle parts of the line pressing sheet supporting spring and the surface line pressing spring are elastically compressed through the rubber ring, the connection stability is improved, the gasket is sleeved on the second bolt and abuts against the rubber ring, and the connection stability can be further improved.

In the above-mentioned upper thread cutting device of the sewing machine, the lower end portions of the first thread tension plate support and the second thread tension plate support are respectively fixed with the thread suction head, the thread suction head is in a cylindrical shape, and one end portion of the thread suction head is opposite to the outer end portions of the thread pressing piece supporting spring and the surface thread pressing spring.

The thread suction head can better suck the thread, so that the thread shifting hook I and the thread shifting hook II can hook the thread more conveniently.

In the upper thread cutting device of the sewing machine, the upper thread cutting device further comprises a thread cutting presser foot component, the thread cutting presser foot component comprises a presser foot handle, the bottom of the presser foot handle is connected with a presser foot plate, and a thread cutting knife is detachably fixed on the presser foot plate through a screw.

The line cutting presser foot subassembly is fixed on compressing tightly the pole, and the presser foot board in the line cutting presser foot subassembly can be dismantled with the presser foot handle and be connected, and it is convenient quick to change, when different needle positions need be changed, only need change the presser foot board of different models, reduces development cost.

The presser foot handle and the presser foot plate are connected through the screws to replace an original pin riveting mode, when a thread cutter in the presser foot component needs to be replaced due to reasons such as abrasion, the purpose of quickly replacing the thread cutter can be achieved, and a quick service concept is embodied.

A sewing machine characterized by: comprises the upper thread cutting device.

Compared with the prior art, the utility model has the following advantages:

1. the upper thread cutting device can simultaneously hook and clamp threads on two needles, so that subsequent thread cutting operation is smoothly carried out, the convenience of operation is improved, and thread separation and thread residue on sewing materials are prevented when a sewing machine is started.

2. In the upper thread cutting device, the head of the upper thread is clamped by the first thread pressing assembly and the second thread pressing assembly when the upper thread is sewn next time, and the upper thread is cut off by the blade below the presser foot assembly due to the effect of certain tension.

Drawings

Fig. 1 is a schematic structural view of the upper thread take-off mechanism.

Fig. 2 is a rear view of the upper thread take-up mechanism.

Figure 3 is an exploded view of a first wire crimping assembly.

Fig. 4 is an exploded view of the wire dialing distance adjustment assembly.

Fig. 5 is a schematic structural view of the thread cutting presser foot assembly.

Fig. 6 is a schematic view showing that the upper thread cutting device is mounted on the sewing machine.

In the figure, 1, a mounting frame; 2. a drive source; 3. an output shaft; 4. a first wire shifting hook frame; 5. a second wire shifting hook frame; 6. a first wire shifting hook; 7. a second wire shifting hook; 8. a first wire pressing assembly; 9. a second wire pressing assembly; 10. a noodle pulling mechanism; 11. a wire-shifting distance adjusting assembly; 12. moving a first plate; 13. moving a second plate; 14. a first support frame; 15. a second support frame; 16. a first bolt; 17. a limiting cover plate; 18. a stopper; 19. a first sliding chute; 20. a second chute; 21. a first strip-shaped groove; 22. a strip-shaped groove II; 23. a first nut; 24. a first guide rod; 25. a drive source joint; 26. a second guide rod; 27. a first wire pressing plate bracket; 28. a wire pressing plate bracket II; 29. the wire pressing sheet supports the spring; 30. a surface wire pressure wire spring; 31. a bending section; 32. a second bolt; 33. a rubber ring; 34. a gasket; 35. a second nut; 36. a thread suction head; 37. a thread cutting presser foot assembly; 38. a presser foot handle; 39. a foot pressing plate; 40. a screw; 41. a thread cutter; 42. a third nut; 43. a sewing machine.

Detailed Description

The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described with reference to the drawings, but the present invention is not limited to these embodiments.

Example one

As shown in fig. 1 and 2, the present noodle cutting device includes an installation frame 1, a drive source 2 is fixed on the installation frame 1, the drive source 2 has an output shaft 3, a first wire-dialing hook frame 4 and a second wire-dialing hook frame 5 are connected on the output shaft 3, the first wire-dialing hook frame 4 and the second wire-dialing hook frame 5 are respectively connected below a first wire-dialing hook 6 and a second wire-dialing hook 7, and the installation frame 1 is further provided with a first wire pressing assembly 8 and a second wire pressing assembly 9 for respectively pressing the noodle.

The upper thread shifting mechanism 10 is formed by a mounting rack 1, a driving source 2, a first thread shifting hook frame 4, a second thread shifting hook frame 5, a first thread pressing assembly 8, a second thread pressing assembly 9 and the like, the upper thread shifting mechanism 10 is mounted on a sewing machine 43, after thread cutting is completed, a machine needle is located in an upper needle stop position, the driving source 2 receives an instruction at the moment, the driving source 2 drives an output shaft 3 to move up and down, the output shaft 3 drives the first thread shifting hook frame 4 and the second thread shifting hook frame 5 to move up or down simultaneously, the first thread shifting hook 6 and the second thread shifting hook 7 respectively hook a first thread on the needle and then move up or down simultaneously, and when the first thread shifting hook 6 and the second thread shifting hook 7 respectively pull the hooked threads to the first thread pressing assembly 8 and the second thread pressing assembly 9 respectively, the first thread pressing assembly 8 and the second thread pressing assembly 9 respectively clamp the corresponding threads.

The driving source 2 may be a linear motor, an oil cylinder, an air cylinder, and the like.

As shown in fig. 1 and 4, in this embodiment, the upper thread cutting device further includes a thread shifting distance adjusting assembly 11, the thread shifting distance adjusting assembly 11 includes a first moving plate 12 and a second moving plate 13, a first support frame 14 and a second support frame 15 are respectively fixed on the first moving plate 12 and the second moving plate 13, the first thread shifting hook frame 4 and the second thread shifting hook frame 5 are respectively connected to the first support frame 14 and the second support frame 15, and the first moving plate 12 and the second moving plate 13 are slidably connected to the mounting frame 1 and can enable the first support frame 14 and the second support frame 15 to be close to or separate from each other.

The first support frame 14 and the second support frame 15 are close to or separate from each other by sliding the first moving plate 12 and the second moving plate 13, the first thread shifting hook frame 4 and the second thread shifting hook frame 5 are close to or separate from each other at the same time, the distance between the first thread shifting hook 6 and the second thread shifting hook 7 can be adjusted according to different double-needle pitches, and the adaptability is good.

As shown in fig. 1, 2 and 4, in this embodiment, the wire shifting distance adjusting assembly 11 further includes a first bolt 16 and a limiting cover plate 17, a stopper 18 is disposed at the bottom of the limiting cover plate 17, bottoms of the first moving plate 12 and the second moving plate 13 abut against the stopper 18, a first sliding groove 19 and a second sliding groove 20 are respectively disposed on the first moving plate 12 and the second moving plate 13, the first sliding groove 19 and the second sliding groove 20 are intersected, a first strip-shaped groove 21 and a second strip-shaped groove 22 are respectively disposed on the limiting cover plate 17 and the mounting frame 1, the first strip-shaped groove 21 and the second strip-shaped groove 22 extend in the vertical direction, the first bolt 16 is inserted into the first strip-shaped groove 21, the first sliding groove 19, the second sliding groove 20 and the second strip-shaped groove 22, a first nut 23 is threadedly connected to an end of the first bolt 16, and the first nut 23 abuts against the mounting frame 1.

In the structure, a first bolt 16 is fixed on the mounting frame 1 in a threaded fastening connection mode with a first nut 23, the first nut 23 is loosened, when the first bolt 16 is moved upwards, the bottoms of a first moving plate 12 and a second moving plate 13 abut against a stop block 18, the first moving plate 12 and the second moving plate 13 do not move in the vertical direction and move oppositely in the horizontal direction, so that a first wire shifting hook frame 4 and a second wire shifting hook frame 5 are close to each other, and the indirect adjustment of a first wire shifting hook 6 and a second wire shifting hook 7 can be realized; conversely, when the first bolt 16 is moved downwards, the first wire shifting hook frame 4 is separated from the second wire shifting hook frame 5, so that the distance between the first wire shifting hook 6 and the second wire shifting hook 7 can be increased.

As shown in fig. 1, in this embodiment, the first guide rods 24 extending in the vertical direction are fixed on the first support frame 14 and the second support frame 15, the upper ends of the first thread shifting hook frame 4 and the second thread shifting hook frame 5 are slidably connected to the corresponding first guide rods 24, the output shaft 3 is fixed with the driving source connector 25, the second guide rods 26 extending in the horizontal direction are fixed on the driving source connector 25, and the first thread shifting hook frame 4 and the second thread shifting hook frame 5 are slidably connected to the second guide rods 26.

The first guide rod 24 and the second guide rod 26 play a role in guiding, and when the output shaft 3 of the driving source 2 drives the first wire shifting hook frame 4 and the second wire shifting hook frame 5 to move up and down, or the first moving plate 12 and the second moving plate 13 respectively drive the first wire shifting hook frame 4 and the second wire shifting hook frame 5 to move horizontally, the stability during movement can be improved.

As an example, the output shaft 3 may be screwed with a coupling nut three 42 and the driving source connector 25 may be pressed against by the coupling nut three 42.

As shown in fig. 2, in the present embodiment, the first wire pressing plate bracket 27 and the second wire pressing plate bracket 28 are respectively fixed on the first supporting frame 14 and the second supporting frame 15, and the first wire pressing assembly 8 and the second wire pressing assembly 9 are respectively fixed on the first wire pressing plate bracket 27 and the second wire pressing plate bracket 28.

As shown in fig. 3, in the present embodiment, the first wire pressing assembly 8 includes a first wire pressing piece supporting spring 29 and a first surface wire pressing spring 30, an inner end portion of the first wire pressing piece supporting spring 29 is fixed to an inner end portion of the first surface wire pressing spring 30 and fixed to the first wire pressing plate bracket 27, an outer end portion of the first wire pressing piece supporting spring 29 has a bending portion 31, the bending portion 31 abuts against an outer end portion of the first surface wire pressing spring 30, and middle portions of the first wire pressing piece supporting spring 29 and the first surface wire pressing spring 30 abut against and are fixed to the first wire pressing plate bracket 27.

In this structure, the wire pressing piece supporting spring 29 and the surface line wire pressing spring 30 both have elasticity, the bending part 31 of the wire pressing piece supporting spring 29 abuts against the outer end part of the surface line wire pressing spring 30, and the bending part 31 and the outer end part of the surface line wire pressing spring 30 clamp the wire hooked by the first wire shifting hook 6 together.

As an embodiment, the second wire pressing assembly 9 has the same structure as the first wire pressing assembly 8, and also includes a wire pressing piece supporting spring 29 and a surface wire pressing spring 30.

As shown in fig. 3, in the present embodiment, the middle portions of the thread pressing piece supporting spring 29 and the upper thread pressing spring 30 are fixed on the first thread pressing plate support 27 through the second bolt 32, the second bolt 32 is sleeved with the rubber ring 33 and the gasket 34, the rubber ring 33 abuts against the upper thread pressing spring 30, the second bolt 32 is connected with the second nut 35 in a threaded manner, and the second nut 35 abuts against the rubber ring 33.

In the structure, the second bolt 32 and the second nut 35 are fastened by threads, and the middle parts of the line pressing sheet supporting spring 29 and the surface line pressing spring 30 are elastically compressed by combining the rubber ring 33, so that the connection stability is improved, and the gasket 34 is sleeved on the second bolt 32 and abuts against the rubber ring 33, so that the connection stability can be further improved.

As shown in fig. 1 or 2, in the present embodiment, the thread suction head 36 is fixed to the lower end portions of the first thread tension plate holder 27 and the second thread tension plate holder 28, respectively, and the thread suction head 36 is cylindrical, and one end portion of the thread suction head 36 is opposed to the outer end portions of the thread tension plate support spring 29 and the thread tension spring 30.

The thread suction head 36 can better suck the thread, so that the first thread shifting hook 6 and the second thread shifting hook 7 can be hooked more conveniently.

As shown in fig. 5 and 6, in the present embodiment, the upper thread cutting device further includes a thread cutting presser foot assembly 37, the thread cutting presser foot assembly 37 includes a presser foot handle 38, a presser foot plate 39 is detachably fixed to the bottom of the presser foot handle 38, and a thread cutting knife 41 is detachably fixed to the presser foot plate 39 through a screw 40.

The thread cutting presser foot component 37 is fixed on the pressing rod, the presser foot plate 39 in the thread cutting presser foot component 37 is detachably connected with the presser foot handle 38, the replacement is convenient and quick, when different needle positions need to be replaced, only the presser foot plate 39 of different models needs to be replaced, and the development cost is reduced.

The presser foot handle 38 and the presser foot plate 39 are connected by the screw 40 to replace the original pin riveting mode, when the thread cutter 41 in the presser foot component needs to be replaced due to the reasons of abrasion and the like, the purpose of quickly replacing the thread cutter 41 can be realized, and the quick service concept is embodied.

Example two

The present embodiment provides a sewing machine including the upper thread cutting device of the first embodiment.

The specific embodiments described herein are merely illustrative of the spirit of the utility model. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the utility model as defined in the appended claims.

Claims (10)

1. The utility model provides a sewing machine's facial line cutting device, facial line cutting device includes mounting bracket (1), be fixed with driving source (2) on mounting bracket (1), driving source (2) have output shaft (3), a serial communication port, be connected with on output shaft (3) and dial a line hook frame (4) and dial line hook frame two (5), the below of dialling line hook frame (4) and dialling line hook frame two (5) is connected with respectively dials line hook one (6) and dials line hook two (7), still be provided with on mounting bracket (1) and be used for respectively carrying out line ball subassembly one (8) and line ball subassembly two (9) that compress tightly to the facial line.

2. The upper thread cutting device of the sewing machine according to claim 1, characterized in that the upper thread cutting device further comprises a first thread shifting distance adjusting assembly (11), the first thread shifting distance adjusting assembly (11) comprises a first moving plate (12) and a second moving plate (13), a first support frame (14) and a second support frame (15) are respectively fixed on the first moving plate (12) and the second moving plate (13), the first thread shifting hook frame (4) and the second thread shifting hook frame (5) are respectively connected to the first support frame (14) and the second support frame (15), and the first moving plate (12) and the second moving plate (13) are slidably connected to the mounting frame (1) and can enable the first support frame (14) and the second support frame (15) to be close to or separate from each other.

3. The upper thread cutting device of the sewing machine according to claim 2, wherein the thread shifting distance adjusting assembly (11) further comprises a first bolt (16) and a limiting cover plate (17), a stop block (18) is arranged at the bottom of the limiting cover plate (17), the bottoms of the first moving plate (12) and the second moving plate (13) are abutted to the stop block (18), a first sliding groove (19) and a second sliding groove (20) are respectively formed in the first moving plate (12) and the second moving plate (13), the first sliding groove (19) and the second sliding groove (20) are crossed, a first strip-shaped groove (21) and a second strip-shaped groove (22) are respectively formed in the limiting cover plate (17) and the mounting frame (1), the first strip-shaped groove (21) and the second strip-shaped groove (22) extend in the vertical direction, and the first bolt (16) penetrates through the first strip-shaped groove (21), the first sliding groove (19), And on the second sliding groove (20) and the second strip-shaped groove (22), a first nut (23) is connected to the end part of the first bolt (16) in a threaded manner, and the first nut (23) abuts against the mounting rack (1).

4. The upper thread cutting device of a sewing machine according to claim 2, wherein the first support frame (14) and the second support frame (15) are respectively fixed with a first guide rod (24) extending along a vertical direction, the first thread shifting hook frame (4) and the second thread shifting hook frame (5) are respectively connected with the corresponding first guide rod (24) in a sliding manner, the output shaft (3) is fixed with a driving source joint (25), the second guide rod (26) extending along a horizontal direction is fixed on the driving source joint (25), and the first thread shifting hook frame (4) and the second thread shifting hook frame (5) are connected with the second guide rod (26) in a sliding manner.

5. The upper thread cutting device for sewing machine according to claim 2, wherein the first support frame (14) and the second support frame (15) are respectively fixed with a first thread pressing plate holder (27) and a second thread pressing plate holder (28), and the first thread pressing assembly (8) and the second thread pressing assembly (9) are respectively fixed on the first thread pressing plate holder (27) and the second thread pressing plate holder (28).

6. The upper thread cutting device of a sewing machine according to claim 5, wherein the first thread pressing member (8) comprises a first thread pressing piece supporting spring (29) and a first thread pressing spring (30), the inner end of the first thread pressing piece supporting spring (29) is fixed with the inner end of the first thread pressing piece supporting spring (30) and the first thread pressing piece supporting spring and the second thread pressing piece supporting spring are fixed on the first thread pressing piece support (27), the outer end of the first thread pressing piece supporting spring (29) is provided with a bending part (31), the bending part (31) abuts against the outer end of the first thread pressing spring (30), and the middle parts of the first thread pressing piece supporting spring (29) and the first thread pressing piece supporting spring (30) abut against and are fixed on the first thread pressing piece support (27).

7. The upper thread cutting device of sewing machine according to claim 6, wherein the middle parts of the thread pressing piece supporting spring (29) and the thread pressing spring (30) are fixed on the first thread pressing plate bracket (27) through a second bolt (32), the second bolt (32) is sleeved with a rubber ring (33) and a gasket (34), the rubber ring (33) abuts against the thread pressing spring (30), the second bolt (32) is in threaded connection with a second nut (35), and the second nut (35) abuts against the rubber ring (33).

8. The upper thread cutting device of sewing machine according to claim 6, wherein the lower end portions of the first thread tension plate holder (27) and the second thread tension plate holder (28) are respectively fixed with a thread suction head (36), the thread suction head (36) is cylindrical, and one end portion of the thread suction head (36) is opposed to the outer end portions of the thread tension plate support spring (29) and the thread tension spring (30).

9. The upper thread cutting device of sewing machine according to claim 1, characterized in that the upper thread cutting device further comprises a cutting thread presser foot assembly (37), the cutting thread presser foot assembly (37) comprises a presser foot handle (38), a presser foot plate (39) is connected to the bottom of the presser foot handle (38), and a cutting thread knife (41) is detachably fixed on the presser foot plate (39) through a screw (40).

10. A sewing machine characterized by: comprising the upper thread cutting device as set forth in any one of the above claims 1 to 9.

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