Sewing machine with double movable cutters for trimming threads

Abstract

The technical scheme belongs to the technical field of sewing machines, and particularly relates to a sewing machine with double movable cutters for trimming threads, which comprises a sewing machine frame, a second driving part is arranged in the sewing machine frame, and the second driving part is provided with a first output end and a second output end which are coaxially arranged; the sewing device is arranged on the sewing machine frame, and the sewing device comprises a rotating shuttle mechanism and a machine needle mechanism; the presser foot lifting device is arranged at the first output end of the second driving part; the thread trimming device is arranged in the sewing machine frame; wherein the thread trimming device comprises a first movable cutter mechanism and a second movable cutter mechanism, the first movable cutter mechanism is used for stretching a sewing thread to a designated position, and the second movable cutter mechanism is used for being matched with the first movable cutter mechanism to trim the thread; and the second movable cutter mechanism is arranged at the second output end of the second driving piece.

Description

Technical Field

[0001] The present technical solution relates to the technical field of sewing machines, and particularly refers to a sewing machine with double moving knives for thread cutting. Background Art

[0002] A sewing machine mainly consists of a base (i.e., a machine shell and a bottom plate), a needle bar mechanism, a feeding mechanism, a thread hooking mechanism, a presser foot mechanism, a thread cutting mechanism, and an accessory part. Through the reasonable cooperation of the movements of each mechanism, it works cyclically to sew the sewing materials together.

[0003] Most of the internal mechanism cooperation of existing sewing machines realizes functions through a "one-driving-three" structure, but the functions have not yet reached the optimal level. In particular, the cooperation between the thread cutting mechanism and the presser foot mechanism is not perfect. Specifically, at the starting and ending stages of sewing, relatively long thread ends will remain on the surface of the fabric. The starting thread ends will form a nest-like shape on the sewn clothing, affecting the quality of the entire clothing, and thus affecting the overall quality of the clothing. To ensure the quality of the clothing, these thread ends must be trimmed manually, which increases the labor intensity and affects the production efficiency.

[0004] To improve the sewing efficiency, an automatic thread cutting mechanism is usually adopted in sewing equipment, which not only makes the sewing smooth but also reduces the thread ends in the clothes and improves the efficiency of subsequent finishing. CN202322683791.X discloses a single moving knife anti-nest thread cutting mechanism and a sewing machine. This technical solution can cut off the too-long part of the sewing thread at the starting stage of sewing and can also cut the sewing thread after the sewing process ends.

[0005] In the actual application process of this technical solution, the thread ends remaining on the fabric surface are still not very ideal. For some ordinary clothes, the length of their thread ends can basically eliminate the need for secondary manual trimming. However, for some high-grade clothes, the length of the thread ends remaining on the fabric is still relatively obvious and still requires manual trimming. Therefore, the applicant further researches and develops and seeks a new technical solution that can achieve a thread cutting effect with shorter thread ends. Summary of the Invention

[0006] The purpose of the present technical solution is to provide a sewing machine that can achieve a better sewing effect and has shorter thread ends after thread cutting. By driving the presser foot lifting device and the thread cutting device to cooperate with each other through a first driving member, and then realizing thread cutting through the cooperation of a first moving knife mechanism and a second moving knife mechanism, it can solve the problems of low cooperation degree among various devices in the original sewing machine, loose stitch, and too long thread ends after thread cutting.

[0007] The purpose of the present technical solution is achieved as follows:

[0008] A sewing machine with a double-acting knife for cutting threads includes: a sewing machine frame, inside which a second driving member is provided, and the second driving member has a first output end and a second output end arranged coaxially; a sewing device, which is arranged on the sewing machine frame, and the sewing device includes a rotary hook mechanism and a needle mechanism; and a thread cutting device, which is arranged inside the sewing machine frame;

[0009] It is characterized in that the thread cutting device includes a first moving knife mechanism and a second moving knife mechanism. The first moving knife mechanism is used to stretch the sewing thread to a specified position, and the second moving knife mechanism is used to cooperate with the first moving knife mechanism to cut the thread; the first moving knife mechanism includes a first driving member, a first transmission component and a first moving knife blade. A needle-passing hole is provided on the first moving knife blade, and the needle tip of the sewing needle passes through the needle-passing hole during the starting sewing stage; the second moving knife mechanism includes a second driving member, a second transmission component and a second moving knife blade, and the second moving knife blade is used to cooperate with the first moving knife blade to cut the thread; wherein, the first moving knife blade and the second moving knife blade are arranged coaxially, the cutting edge of the second moving knife blade is movably attached to the upper surface of the first moving knife blade, and when the cutting edge of the second moving knife blade slides over the cutting edge at the front part of the lead wire groove of the first moving knife blade, the first moving knife blade and the second moving knife blade cooperate to cut the sewing thread; the second driving member has a first output end and a second output end arranged coaxially; the second output end drives the second transmission component and the second moving knife blade; the first output end drives the presser foot lifting device and / or the stitch length adjusting device arranged on the sewing machine frame; the presser foot lifting device is used to lift or lower the sewing presser foot; the stitch length adjusting device is used to adjust the sewing stitch length; the thread cutting device further includes a thread clamping piece, which is arranged on the sewing machine frame and is located inside the movement path of the first moving knife blade; when the needle-passing hole of the first moving knife blade moves to the position of the thread clamping piece, the thread clamping piece cooperates with the first moving knife blade to clamp the sewing thread in the needle-passing hole.

[0010] Preferably, the presser foot lifting device includes: a presser foot rotating shaft, which is inserted on the oil box of the sewing machine frame; and a presser foot crank, which is arranged on the presser foot rotating shaft, and the presser foot crank has a first abutting end and a second abutting end; wherein, the first abutting end is movably abutted on the presser foot bearing sleeved outside the first output end, and the second abutting end is used to push the presser foot lever to lift and lower; it also includes: a presser foot spring, which is sleeved outside the presser foot rotating shaft, one end of the presser foot spring abuts on the sewing machine frame, and the other end is placed on the first abutting end.

[0011] Preferably, the thread cutting device further includes a suction device, which is arranged outside the movement path of the first moving knife blade and is used to suck away the cut sewing thread; the suction port of the suction device is arranged outside the clamping piece and faces the thread clamping piece.

[0012] Preferably, the first transmission assembly includes: a first movable block disposed at the output end of the first driving member, and a first abutting block protruding from the side of the first movable block; a first crank hinged to the end cover of the first driving member and having a first sliding groove at the front end, and the first abutting block is movably clamped in the first sliding groove; a first transmission rod, the front end of which is disposed at the rear end of the first crank; and a first tool rest rotatably sleeved on the shuttle shaft of the shuttle mechanism and connected to the rear end of the first transmission rod; wherein, the first moving knife blade is disposed on the first tool rest, and the first movable block drives the first crank to rotate through the first abutting block, and then drives the first tool rest to rotate through the first transmission rod.

[0013] Preferably, the first crank is in a "V" shape, and a first hinge shaft is disposed on the lower side of the middle of the first crank, and the first hinge shaft is rotatably installed on the end cover of the first driving member; a first sliding groove is formed on one side wall of the first crank, and a first output rod is formed on the other side wall, and the upper end of the first output rod is hinged to the first transmission rod.

[0014] Preferably, a needle-passing hole and a lead wire groove are formed on the first moving knife blade, and the needle-passing hole and the lead wire groove are arranged along the rotation direction of the first moving knife blade; the needle-passing hole is formed at the tail part of the first moving knife blade for the needle tip of the sewing needle to pass through and hook the thread at the same time; the lead wire groove is formed on the front side of the needle-passing hole and communicates with the outside for hooking the thread.

[0015] Preferably, the second transmission assembly includes: a second movable block disposed at the output end of the second driving member, and a second abutting block protruding from the side of the second movable block; a second crank having a second annular groove at the front end, and the second abutting block is movably abutted in the second annular groove; a second transmission block disposed at the rear end of the second crank; a second transmission rod, the front end of which is disposed at the rear end of the second transmission block; and a second tool rest rotatably sleeved on the shuttle shaft of the shuttle mechanism and connected to the rear end of the second transmission rod; wherein, the second moving knife blade is disposed on the second tool rest, and the second movable block drives the second crank to rotate through the second abutting block, and then drives the second tool rest to rotate through the second transmission block and the second transmission rod.

[0016] Preferably, the second moving knife mechanism further includes: a second limiting portion disposed on the second transmission block, and the side of the second limiting portion is movably abutted against the sewing machine frame; and a second torsion spring sleeved outside the second crank, with the front end thereof clamped in the sewing machine frame and the rear end abutted against the second limiting portion, for making the second limiting portion always have a tendency to move towards the sewing machine frame.

[0017] The prominent and beneficial technical effects of this technical solution compared with the prior art are:

[0018] 1. The thread cutting device designed in this technical solution has an independent first moving knife mechanism and a second moving knife mechanism that can cooperate with each other. The first moving knife mechanism is used to stretch the sewing thread to a specified position before cutting, and the second moving knife mechanism is used for cutting the thread. Straightening the sewing thread in this way can achieve better sewing or cutting effects, making the stitches at the starting and ending points of the fabric more compact. At the same time, the thread clamping piece can automatically clamp the sewing thread in cooperation with the first moving knife blade, making the stitches more stable during sewing.

[0019] 2. The thread clamping piece designed in this technical solution can clamp the cut sewing thread, and the suction device can suck away the cut sewing thread, which can ensure that the cut sewing thread does not affect normal sewing and at the same time ensure the internal cleanliness of the working mechanism of the sewing machine.

[0020] 3. The first moving knife mechanism designed in this technical solution includes a "V"-shaped first crank, and the crank is hinged on the end cover of the first driving part. This setting method is because the space under the sewing machine frame is extremely narrow. This structure can not only achieve the transmission of the first moving knife mechanism but also make the trajectories of the first driving part during forward and reverse rotations and the first moving knife blade consistent. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of this technical solution.

[0022] Figure 2 is a schematic structural diagram of the thread cutting device.

[0023] Figure 3 is a schematic structural diagram of the presser foot lifting device.

[0024] Figure 4 is a schematic structural diagram of the first moving knife mechanism.

[0025] Figure 5 is a schematic structural diagram of the second moving knife mechanism.

[0026] Figure 6 is a schematic structural diagram of the clip and the suction device.

[0027] Figure 7 is a state diagram when the clip clamps the sewing thread.

[0028] Figure 8 is a schematic structural diagram of the first tool holder and the second tool holder.

[0029] Reference numerals: 1, sewing machine frame; 11, second driving member; 12, first output end; 13, second output end; 14, oil box; 2, sewing device; 21, rotary hook mechanism; 211, rotary hook shaft; 22, needle mechanism; 221, needle tip; 3, presser foot lifting device; 31, presser foot lifting rotating shaft; 32, presser foot lifting crank; 33, first abutting end; 34, second abutting end; 35, presser foot bearing; 36, presser foot rod; 37, presser foot spring; 4, thread cutting device; 41, first moving knife mechanism; 42, second moving knife mechanism; 43, first driving member; 44, first transmission assembly; 45, first moving knife blade; 451, needle threading hole; 452, lead wire groove; 46, second transmission assembly; 47, second moving knife blade; 471, cutting edge; 48, thread clamping piece; 49, air suction device; 40, air suction port; 51, first movable block; 52, first abutting block; 53, first crank; 531, first hinge shaft; 532, first output rod; 54, first chute; 55, first transmission rod; 56, first tool holder; 61, second movable block; 62, second abutting block; 63, second crank; 64, second annular groove; 65, second transmission block; 66, second transmission rod; 67, second tool holder; 68, second limiting portion; 69, second torsion spring. Detailed implementation manners

[0030] The following further elaborates on the detailed implementation manners of the technical solution in conjunction with the drawings.

[0031] As Figure 1-8 shown, a sewing machine with double moving knives for thread cutting includes a sewing machine frame 1, a sewing device 2, a presser foot lifting device 3, and a thread cutting device 4;

[0032] The sewing device 2 and the presser foot lifting device 3 are both arranged on the sewing machine frame 1. The sewing device 2 includes a rotary hook mechanism 21 and a needle mechanism 22. The rotary hook mechanism 21 is used to hook the upper thread on the needle tip 221 and provide the bobbin thread. The needle mechanism 22 is used for sewing. The thread cutting device 4 is arranged inside the sewing machine frame 1. The thread cutting device 4 includes a first moving knife mechanism 41 and a second moving knife mechanism 42. The first moving knife mechanism 41 is used to stretch the sewing thread to a specified position, and the second moving knife mechanism 42 is used to cooperate with the first moving knife mechanism 41 for thread cutting.

[0033] The first moving knife mechanism 41 and the second moving knife mechanism 42 are horizontally arranged and compactly arranged, which can save the internal space of the sewing machine and provide installation space for the remaining devices inside the sewing machine;

[0034] The first moving knife mechanism 41 includes a first driving member 43, a first transmission assembly 44, and a first moving knife blade 45. The first driving member 43 is used to output power, the first transmission assembly 44 transmits power, and the first moving knife blade 45 is used to stretch the sewing thread to a specified position;

[0035] The second moving cutter mechanism 42 includes a second driving member 11, a second transmission assembly 46, and a second moving cutter blade 47. The second driving member 11 is used to output power, the second transmission assembly 46 transmits the power, and the second moving cutter blade 47 is used to cooperate with the first moving cutter blade 45 to cut the thread. The first moving cutter mechanism 41 and the second moving cutter mechanism 42 have independent power sources and transmission assemblies, which can ensure that the thread cutting device 4 does not have movement interference during operation.

[0036] Furthermore, the output ends of the first moving cutter mechanism 41 and the second moving cutter mechanism 42 are coaxially arranged and are jointly rotatably sleeved on the bobbin spindle 211. Specifically, the first moving cutter blade and the second moving cutter blade are coaxially arranged, which can ensure the fitting tightness between the first moving cutter blade 45 and the second moving cutter blade 47. At the same time, the first moving cutter blade 45 and the second moving cutter blade 47 move on the periphery of the bobbin mechanism 21, and the needle tip 221 of the sewing needle moves above the bobbin mechanism 21 (in order to clearly show the structure of the thread cutting device 4, the bobbin mechanism 21 is not shown in the drawings). Therefore, the needle tip 221 of the sewing needle can pass through the first moving cutter blade 45 and extend into the bobbin mechanism 21.

[0037] The rotation radius of the first moving cutter blade 45 is slightly smaller than that of the second moving cutter blade 47, so that the cutting edge 471 of the second moving cutter blade 47 can movably fit on the upper surface of the first moving cutter blade 45. When the cutting edge 471 of the second moving cutter blade 47 slides over the cutting edge at the front end of the lead groove 452 of the first moving cutter blade 45, it is the thread cutting position of the thread cutting device 4.

[0038] The second driving member 11 has a first output end 12 and a second output end 13 that are coaxially arranged; the second output end 13 drives the second transmission assembly 46 and the second moving cutter blade 47;

[0039] The first output end 12 drives the presser foot lifting device 3 and / or the stitch length adjusting device; the presser foot lifting device 3 is used to lift or lower the sewing presser foot; the stitch length adjusting device is used to adjust the sewing stitch length. The specific structures of the presser foot lifting device 3 and the stitch length adjusting device have been disclosed in the patent document with the patent number CN202211193682.3 and the invention title: A Sewing Machine, and will not be elaborated in detail in this application.

[0040] Therefore, the second moving cutter mechanism 42, the presser foot lifting device 3, and / or the stitch length adjusting device share the second driving member 11, which can realize a closer combination of the thread cutting function, the presser foot lifting function, or the stitch length adjusting function of the sewing machine.

[0041] Such as Figure 1-8As shown, the thread cutting device 4 includes a first moving knife mechanism 41 and a second moving knife mechanism 42. The first moving knife mechanism 41 and the second moving knife mechanism 42 are horizontally arranged and compactly arranged, which can save the internal space of the sewing machine and provide installation space for the remaining devices inside the sewing machine. The first moving knife mechanism 41 includes a first driving member 43, a first transmission assembly 44 and a first moving knife blade 45. The first driving member 43 is used to output power, the first transmission assembly 44 transmits power, and the first moving knife blade 45 is used to stretch the sewing thread to a specified position; the second moving knife mechanism 42 includes a second driving member 11, a second transmission assembly 46 and a second moving knife blade 47. The second driving member 11 is used to output power, the second transmission assembly 46 transmits power, and the second moving knife blade 47 is used to cooperate with the first moving knife blade 45 to cut the thread. The first moving knife mechanism 41 and the second moving knife mechanism 42 have independent power sources and transmission assemblies, which can ensure that the thread cutting device 4 will not have movement interference during operation.

[0042] Furthermore, the output ends of the first moving knife mechanism 41 and the second moving knife mechanism 42 are coaxially arranged and are jointly rotatably sleeved on the bobbin spindle 211, which can ensure the fitting tightness between the first moving knife blade 45 and the second moving knife blade 47. At the same time, the first moving knife blade 45 and the second moving knife blade 47 move on the periphery of the bobbin mechanism 21, and the needle tip 221 moves above the bobbin mechanism 21 (in order to clearly show the structure of the thread cutting device 4, the bobbin mechanism 21 is not shown in the drawings). Therefore, the needle tip 221 can pass through the first moving knife blade 45 and extend into the bobbin mechanism 21.

[0043] The rotation radius of the first moving knife blade 45 is slightly smaller than that of the second moving knife blade 47, so that the cutting edge 471 of the second moving knife blade 47 can movably fit on the upper surface of the first moving knife blade 45. When the cutting edge 471 of the second moving knife blade 47 slides over the cutting edge at the front end of the lead groove 452 of the first moving knife blade 45, it is the thread cutting position of the thread cutting device 4.

[0044] As Figure 3As shown in the figure, the first transmission component 44 includes a first movable block 51, a first crank 53, a first transmission rod 55, and a first tool rest 56. The first movable block 51 is arranged at the output end of the first driving member 43, and the first driving member 43 can be set as a motor. The first movable block 51 rotates following the motor shaft. The middle part of the first crank 53 is hinged to the end cover of the first driving member 43. The front end has a first chute 54 and the rear end extends outwards. The front end of the first movable block 51 protrudes to form a first abutting block 52, and the first abutting block 52 is movably clamped in the first chute 54. When the first abutting block 52 moves in the first chute 54, the front end of the first crank 53 swings, thereby driving the first crank 53 to rotate around its hinge point with the end cover of the first driving member 43, and then driving the rear end of the first crank 53 to swing accordingly. The first tool rest 56 is sleeved on the rotating hook shaft 211 and can rotate around the rotating hook shaft 211. The first transmission rod 55 is used to connect the rear end of the first crank 53 and the first tool rest 56. At the same time, the first moving knife blade 45 is arranged on the first tool rest 56 through screws. Thus, the first driving member 43 can drive the first moving knife blade 45 to rotate.

[0045] Furthermore, the first crank 53 is in a "V" shape. A first hinge shaft 531 is arranged on the lower side of the middle part of the first crank 53. The first hinge shaft 531 is rotatably installed on the end cover of the first driving member 43. A first chute 54 is formed on one side wall of the first crank 53, and a first output rod 532 is formed on the other side wall. The upper end of the first output rod 532 is hinged to the first transmission rod 5'. Since the space under the sewing machine frame 1 is extremely narrow, the "V"-shaped first crank 53 is directly hinged to the end cover of the first driving member 43, which can not only realize the transmission of the first moving knife mechanism 41, but also save the internal space of the sewing machine frame 1. At the same time, the setting method of the first chute 54 can ensure that the moving track of the first moving knife blade 45 is the same when the first driving member 43 rotates forward and backward.

[0046] Furthermore, a thread-piercing hole 451 and a thread-leading groove 452 are formed on the first moving knife blade 45. The thread-piercing hole 451 is convenient for the sewing machine to cut the thread when starting to sew, and the thread-leading groove 452 is convenient for the sewing machine to cut the thread when finishing sewing. The thread-piercing hole 451 and the thread-leading groove 452 are arranged along the rotation direction of the first moving knife blade 45. The thread-piercing hole 451 is formed at the knife tail part of the first moving knife blade 45 for the needle tip 221 of the sewing needle to pass through and hook the thread at the same time. The thread-leading groove 452 is formed on the front side of the thread-piercing hole 451 and communicates with the outside for hooking the thread. The front end of the thread-leading groove 452 has a cutting edge. When the sewing thread is in the thread-piercing hole 451 or the thread-leading groove 452, it will not be cut when not under pressure. It will not be cut until the cutting edge 471 of the second moving knife blade 47 coincides with the cutting edge.

[0047] Furthermore, the front end of the lead wire groove 452 is recessed and formed on the surface of the first moving knife blade 45. It can penetrate or not penetrate the first moving knife blade 45. The function of the front end of the lead wire groove 452 is to provide an avoidance space for the sewing thread to be pushed, ensuring that the sewing thread will not be worn and broken during the pushing process.

[0048]

Variant Example

[0049] Such as Figure 3 As shown, the main reason for the first transmission component 44 to adopt the cooperation mode of the slider and the chute is that the first moving knife blade 45 needs to rotate forward and backward during actual work. Compared with the motor, it is necessary to ensure that the trajectory of the first moving knife blade 45 is consistent. Therefore, the cooperation mode of the slider and the chute is adopted.

[0050] Such as Figure 4 As shown, the second transmission component 46 includes a second movable block 61, a second crank 63, a second transmission block 65, a second transmission rod 66 and a second tool rest 67. The second movable block 61 is arranged at the output end of the second driving member 11. The second driving member 11 can be arranged as a motor. The second movable block 61 rotates following the motor shaft. The second crank 63 is rotatably arranged on the sewing machine frame 1 through a bushing. The front end of the second crank 63 has a second annular groove 64, and the rear end is provided with a second transmission block 65. Therefore, the movement direction of the second annular groove 64 is synchronized with the movement direction of the second transmission block 65. A second abutting block 62 protrudes from the side of the second movable block 61, and the second abutting block 62 is movably abutted in the second annular groove 64. When the second abutting block 62 moves in the second annular groove 64, the second transmission block 65 follows the movement. The second tool rest 67 is sleeved on the rotary hook shaft 211 and can rotate around the rotary hook shaft 211. The second transmission rod 66 is used to connect the second transmission block 65 and the second tool rest 67. At the same time, the second moving knife blade 47 is arranged on the second tool rest 67 through screws. Thus, the second driving member 11 can drive the second moving knife blade 47 to rotate.

[0051] Further, the main reason for the second transmission component 46 to adopt the cooperation mode of the crank and the annular groove is that this cooperation mode is more suitable for the movement mode of the second moving knife blade 47.

[0052] Such as Figure 4 And Figure 8As shown, the second moving cutter mechanism 42 further includes a second limiting portion 68 and a second torsion spring 69. The second limiting portion 68 is disposed on the second transmission block 65. The second limiting portion 68 can also be integrally formed with the second transmission block 65. The end side of the second limiting portion 68 movably abuts against the sewing machine frame 1 to limit the rotation angle of the second transmission block 65. The second torsion spring 69 is sleeved outside the second crank 63. Its front end is fixedly clamped inside the sewing machine frame 1, and the rear end abuts against the second limiting portion 68. The second torsion spring 69 is used to make the limiting portion always have a tendency to move towards the sewing machine frame 1, so as to realize the reset of the second transmission block 65 and the second limiting portion 68.

[0053] As Figure 5 and Figure 6 shown, the thread cutting device 4 further includes a thread clamping piece 48 and an air suction device 49. The thread clamping piece 48 is fixedly disposed on the sewing machine frame 1. The front end of the thread clamping piece 48 extends towards the rotating hook mechanism 21 and is located inside the movement path of the first moving cutter blade 45. When the needle tip 221 of the sewing needle makes the first downward needle and moves up to a certain height, the surface thread will remain in the needle-passing hole 451 of the first moving cutter blade 45. The first needle will not hook the bottom thread in the rotating hook mechanism 21. Then, when the first moving cutter blade 45 moves to the outside of the thread clamping piece 48, the needle-passing hole 451 drives the surface thread to the position of the thread clamping piece 48. The thread clamping piece 48 cooperates with the needle-passing hole 451 of the first moving cutter blade 45 to clamp the sewing thread. At this time, both the first moving cutter blade 45 and the second moving cutter blade 47 pause rotating. The fabric moves and the needle tip 221 of the sewing needle performs the second needle sewing. Since the clamped sewing thread is in the position shown in the figure and one end of it is clamped, when the needle tip 221 performs the second needle sewing, the stitch will not be loose. And after the second needle sewing is completed, the first moving cutter blade 45 and the second moving cutter blade 47 continue to rotate until the thread cutting is completed, which can ensure that the sewing thread will not loosen on the fabric surface. Therefore, the design of the thread clamping piece 48 can obtain better sewing and thread cutting effects.

[0054] The air suction device 49 is disposed outside the movement path of the first moving cutter blade 45. At the same time, the air suction port 40 of the air suction device 49 is aligned with the thread clamping position of the thread clamping piece 48. The air suction port 40 of the air suction device 49 is disposed outside the clamping piece and faces the clamping piece, so as to adsorb the cut sewing thread in the first time.

[0055] As Figure 8 shown, both the first tool holder 56 and the second tool holder 67 are sleeved outside the rotating hook shaft 211 through bushings. A gasket is disposed between the first tool holder 56 and the second tool holder 67. A locking piece is disposed outside the first tool holder 56. The locking piece can stably install the first tool holder 56 and the second tool holder 67 on the bushing.

[0056] The above has shown and described the basic principles, main features and advantages of the present technical solution. Those skilled in the art should understand that the present technical solution is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principles of the present technical solution. Without departing from the spirit and scope of the present technical solution, the present technical solution will have various changes and improvements, and these changes and improvements all fall within the scope of the present technical solution claimed. The scope of protection required by the present technical solution is defined by the appended claims and their equivalents.

Claims

1. A sewing machine with a double-acting knife for cutting threads, comprising: A sewing machine frame (1) which is internally provided with a second driving member (11), and the second driving member (11) has a coaxially arranged first output end (12) and a second output end (13); A sewing device (2) which is arranged on the sewing machine frame (1), and the sewing device (2) includes a rotary hook mechanism (21) and a sewing needle mechanism (22); and A thread cutting device (4) which is arranged inside the sewing machine frame (1); It is characterized in that The thread cutting device (4) includes a first moving knife mechanism (41) and a second moving knife mechanism (42), the first moving knife mechanism (41) is used for stretching the sewing thread to a designated position, and the second moving knife mechanism (42) is used for cooperating with the first moving knife mechanism (41) to cut the thread; The first moving knife mechanism (41) includes a first driving member (43), a first transmission assembly (44) and a first moving knife blade (45), and a thread-passing hole (451) is arranged on the first moving knife blade (45), and the needle head (221) of the sewing needle during the starting sewing stage passes through the thread-passing hole (451); The second moving knife mechanism (42) includes a second driving member (11), a second transmission assembly (46) and a second moving knife blade (47), and the second moving knife blade (47) is used for cooperating with the first moving knife blade (45) to cut the thread; Wherein, the first moving knife blade (45) and the second moving knife blade (47) are coaxially arranged, the cutting edge (471) of the second moving knife blade (47) is movably attached to the upper surface of the first moving knife blade (45), and when the cutting edge (471) of the second moving knife blade (47) slides over the cutting edge at the front part of the thread-leading groove (452) of the first moving knife blade (45), the first moving knife blade (45) and the second moving knife blade (47) cooperate to cut the sewing thread; The second driving member (11) has a coaxially arranged first output end (12) and a second output end (13); The second output end (13) drives the second transmission assembly (46) and the second moving knife blade (47); The first output end (12) drives the presser foot lifting device (3) and / or the stitch length adjusting device arranged on the sewing machine frame (1); the presser foot lifting device (3) is used for lifting or lowering the sewing presser foot; the stitch length adjusting device is used for adjusting the sewing stitch length; The thread cutting device (4) further includes a thread clamping piece (48), which is arranged on the sewing machine frame (1) and is located inside the movement path of the first moving knife blade (45); When the thread-passing hole (451) of the first moving knife blade (45) moves to the position of the thread clamping piece (48), the thread clamping piece (48) cooperates with the first moving knife blade (45) to clamp the sewing thread in the thread-passing hole (451).

2. The sewing machine with a double-acting knife for cutting threads according to claim 1, characterized in that, The presser foot lifting device (3) includes: A presser foot lifting rotating shaft (31) which is inserted into the oil box (14) of the sewing machine frame (1); and A presser foot lifting crank (32) which is arranged on the presser foot lifting rotating shaft (31), and the presser foot lifting crank (32) has a first abutting end (33) and a second abutting end (34); Among them, the first abutting end (33) abuts against the lifting presser foot bearing (35) sleeved outside the first output end (12) movably, and the second abutting end (34) is used to push the lifting presser foot rod (36) to lift and lower. It further includes: A lifting presser foot spring (37) sleeved outside the lifting presser foot rotating shaft (31), one end of the lifting presser foot spring (37) abuts against the sewing machine frame (1), and the other end is placed on the first abutting end (33).

3. The sewing machine with a double-acting knife for thread cutting according to claim 2, characterized in that: The thread cutting device (4) further includes an air suction device (49) arranged outside the movement path of the first moving knife blade (45) for sucking away the cut sewing thread. The air suction port (40) of the air suction device (49) is arranged outside the clamping piece and faces the thread clamping piece (48).

4. A sewing machine with double-acting knife for thread cutting according to claim 3, characterized in that The first transmission assembly (44) includes: A first movable block (51) arranged at the output end of the first driving member (43), and a first abutting block (52) protrudes from the end side of the first movable block (51). A first crank (53) hinged on the end cover of the first driving member (43), and a first chute (54) is formed at the front end thereof, and the first abutting block (52) is movably clamped in the first chute (54). A first transmission rod (55) with its front end arranged at the rear end of the first crank (53); and A first tool rest (56) rotatably sleeved on the rotating shuttle shaft (211) of the rotating shuttle mechanism (21) and connected to the rear end of the first transmission rod (55). Among them, the first moving knife blade (45) is arranged on the first tool rest (56), and the first movable block (51) drives the first crank (53) to rotate through the first abutting block (52), and then drives the first tool rest (56) to rotate through the first transmission rod (55).

5. A sewing machine with a double-acting knife for cutting threads according to claim 4, characterized in that: The first crank (53) is in a "V" shape, and a first hinge shaft (531) is arranged on the lower side of the middle part of the first crank (53), and the first hinge shaft (531) is rotatably installed on the end cover of the first driving member (43). A first chute (54) is formed on one side wall of the first crank (53), and a first output rod (532) is formed on the other side wall, and the upper end of the first output rod (532) is hinged to the first transmission rod (55).

6. A sewing machine with a double-acting knife for cutting threads, characterized in that: A needle passing hole (451) and a wire guiding groove (452) are formed on the first moving knife blade (45), and the needle passing hole (451) and the wire guiding groove (452) are arranged along the rotation direction of the first moving knife blade (45). The needle passing hole (451) is formed at the tail part of the first moving knife blade (45) for the needle tip (221) of the sewing needle to pass through and hook the thread at the same time. The wire guiding groove (452) is formed on the front side of the needle passing hole (451) and communicates with the outside for hooking the thread.

7. The double-acting knife thread trimming sewing machine according to claim 6, characterized in that, The second transmission assembly (46) includes: A second movable block (61) arranged at the output end of the second driving member (11), and a second abutting block (62) protrudes from the end side of the second movable block (61). A second crank (63) with a second ring groove (64) formed at the front end, and the second abutting block (62) abuts against the second ring groove (64) movably. The second transmission block (65), which is arranged at the rear end of the second crank (63); The second transmission rod (66), the front end of which is arranged at the rear end of the second transmission block (65); and The second tool rest (67), which is rotatably sleeved on the bobbin spindle (211) of the bobbin mechanism (21) and is connected to the rear end of the second transmission rod (66); Wherein, the second moving knife blade (47) is arranged on the second tool rest (67), and the second movable block (61) pushes the second crank (63) to rotate through the second abutting block (62), and then drives the second tool rest (67) to rotate through the second transmission block (65) and the second transmission rod (66).

8. A sewing machine with double-acting knife for thread cutting according to claim 7, characterized in that: The second moving knife mechanism (42) further includes: The second limiting portion (68), which is arranged on the second transmission block (65), and the end side of the second limiting portion (68) movably abuts against the sewing machine frame (1); and The second torsion spring (69), which is sleeved outside the second crank (63), the front end of which is clamped inside the sewing machine frame (1), and the rear end of which abuts against the second limiting portion (68), and is used for making the second limiting portion (68) always have a tendency to move towards the sewing machine frame (1).

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