Thread trimming device of flat seaming machine and flat seaming machine

Abstract

The invention provides a thread trimming device of a flat seaming machine and the flat seaming machine, and belongs to the technical field of sewing equipment. The flat seaming machine comprises a machine shell, the thread trimming device comprises a motor, a fixed cutter, a movable cutter and a connecting rod assembly driving the movable cutter to move, a pin shaft and a push rod are arranged at the lower end of an output shaft of the motor, and a protruding part is arranged at one end of the push rod and rotationally connected to the lower end of the output shaft of the motor. The other end of the push rod is connected with the connecting rod assembly, and the pin shaft can abut against the protruding part and push the push rod to swing. The thread trimming device pushes the push rod to rotate through the pin shaft, the push rod can drive the movable cutter to move through the connecting rod assembly, and automatic thread trimming is conveniently conducted.

Description

Technical Field

[0001] The invention belongs to the technical field of sewing equipment and relates to a thread trimming device of a stretch sewing machine and the stretch sewing machine. Background Art

[0002] When a flat sewing machine is sewing fabric, a thread trimming mechanism is required to trim the thread. In the prior art, the structure of the thread trimming mechanism is relatively complicated.

[0003] In order to solve the above technical problems, the patent document with application number 201610273567.5 provides a thread trimming mechanism for a sewing machine, which includes: a driving motor and a main transmission rod connected to the driving motor; a transmission mechanism, including multiple connecting rods connected in sequence, and divided into a front section and a rear section, the front section is slidingly connected to the rear section, the rear section is connected to a reset mechanism, the first connecting rod in the transmission mechanism is connected to the main transmission rod, and the last connecting rod in the transmission mechanism is rotatably positioned on the casing of the sewing machine; a scissors assembly for completing thread cutting, including a blade that can move forward and backward, the blade body is connected to the last connecting rod, when the driving motor rotates, the blade body is driven forward by the main transmission rod and the last connecting rod, when the driving motor is reset, the reset mechanism drives the rear section to reset and at the same time drives the blade backward through the last connecting rod to complete thread cutting.

[0004] The above-mentioned thread trimming mechanism simplifies the structure to a certain extent. However, designing a thread trimming mechanism with a different structure is the direction of efforts of those skilled in the art. Summary of the Invention

[0005] In view of the above problems existing in the prior art, the present invention provides a thread trimming device for a flat sewing machine. The technical problem to be solved by the present invention is: how to perform automatic thread trimming.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A thread trimming device for a stretch sewing machine, the stretch sewing machine comprising a casing, the thread trimming device comprising a motor, a fixed knife, a movable knife and a connecting rod assembly for driving the movable knife to move, characterized in that a pin shaft and a push rod are provided at the lower end portion of the output shaft of the motor, one end of the push rod has a protrusion and the end of the push rod is rotatably connected to the lower end portion of the output shaft of the motor, the other end of the push rod is connected to the connecting rod assembly, the pin shaft can abut against the protrusion and push the push rod to swing.

[0008] Its working principle is: in this thread trimming device, one end of the push rod is sleeved on the lower end of the output shaft of the motor and can rotate. When the motor rotates, the pin shaft rotates with the output shaft. When the pin shaft abuts against the protruding part of the push rod, the pin shaft pushes the push rod to rotate, and the other end of the push rod drives the connecting rod assembly to move. The connecting rod assembly drives the movable knife to move, and the movable knife moves relative to the fixed knife to complete the thread trimming.

[0009] The thread trimming device drives the push rod to rotate through the pin shaft, and the push rod can drive the movable knife to move through the connecting rod assembly, so that the thread trimming can be carried out automatically.

[0010] In the above-mentioned thread trimming device of a flat sewing machine, a mounting plate is provided on the casing, a movable moving knife holder is provided on the mounting plate, the connecting rod assembly includes a connecting rod 1, one end of the connecting rod 1 is hinged to one end of the push rod, the other end of the connecting rod 1 is connected to a connecting rod 2, one end of the connecting rod 2 is hinged to a connecting rod 3, one end of the connecting rod 3 is hinged to a rocker arm, the middle part of the rocker arm is hinged to the mounting plate, one end of the rocker arm is hinged to the moving knife holder, the moving knife is mounted on the moving knife holder, the fixed knife is mounted on the mounting plate, and the moving knife is in contact with the fixed knife.

[0011] Connecting rod two is movably connected to the casing. When the motor rotates, the pin shaft pushes the push rod to rotate, the push rod drives connecting rod one to move, connecting rod one drives connecting rod two to move, connecting rod two drives connecting rod three to swing, connecting rod three drives the swing rod to swing, the swing drives the movable knife holder to move, the movable knife moves with the movable knife holder, and the movable knife moves relative to the fixed knife to complete the thread cutting.

[0012] As an embodiment, the fixed knife is installed on the mounting plate through the fixed knife holder, and the connecting rod 1 and the connecting rod 2 are connected through a connecting block. The connecting block is connected to one end of the connecting rod 1, and one end of the connecting rod 2 is connected to the connecting block.

[0013] In the above-mentioned thread trimming device of a flat sewing machine, a mounting block is fixed on the casing, a mounting groove is provided on the mounting block, a sliding groove is provided on the bottom wall of the mounting groove, the second connecting rod is slidably connected to the mounting block, a spring and a slider are sleeved on the second connecting rod, the upper half of the slider and the spring are located in the mounting groove, one end of the spring rests on the groove wall of the mounting groove, the other end of the spring rests on the upper half of the slider, and the lower half of the slider is slidably connected in the sliding groove.

[0014] The upper half of the slider is fixed on connecting rod 2. When the motor rotates clockwise, the push rod drives connecting rod 2 to move through connecting rod 1 (at this time the spring is gradually in a compressed state), and connecting rod 2 drives the movable knife to move relative to the fixed knife through connecting rod 3 and the rocker arm to complete the thread trimming. After that, the motor rotates counterclockwise, and the spring pushes connecting rod 2 to move in the opposite direction, so that the movable knife automatically resets, improving the convenience of operation.

[0015] During the movement of the second connecting rod, the lower half of the second slider moves in the slide groove. The slider and the slide groove form a guide structure, which greatly improves the stability of the second connecting rod during movement and also improves the accuracy of transmission.

[0016] In the above-mentioned thread trimming device of a flat sewing machine, the pin shaft is cylindrical, the protruding portion has an arc-shaped groove, and the pin shaft can be in contact with the inner wall of the groove.

[0017] One side of the groove is open. After the pin rotates into the groove, it abuts against the inner wall of the groove and pushes the push rod to rotate. This structure allows the pin to more fully contact the protrusion of the push rod, ensuring transmission stability. During transmission, the pin is located in the groove, ensuring close contact between the pin and the protrusion, preventing them from separating.

[0018] In the above-mentioned thread trimming device of the interlock sewing machine, a positioning plate 1 is sleeved and fixed on the lower end portion of the output shaft of the motor, and the pin shaft is arranged on one side of the positioning plate 1.

[0019] The pin shaft can be a part of the positioning plate one, that is, the two are an integrated structure, and the pin shaft can also be detachably fixed on the positioning plate one.

[0020] In the above-mentioned thread trimming device of a flat sewing machine, the lower end of the output shaft of the motor is also sleeved and fixed with a positioning disk 2, and the upper end of the push rod has a connecting ring, which is sleeved on the lower end of the output shaft of the motor, and the bottom of the positioning disk 1 and the top of the positioning disk 2 are respectively provided with accommodating grooves, and mounting seats are respectively installed in the accommodating grooves, and the mounting seats are sleeved on the output shaft of the motor, and the mounting seats are respectively provided with rotatable rollers, which are distributed along the circumference of the corresponding mounting seats and extend from the inside to the outside, and the connecting ring is located between the positioning disk 1 and the positioning disk 2, and the top and bottom of the connecting ring respectively rest on the rollers of each mounting seat.

[0021] In this structure, the rollers on the two mounting seats are respectively located above and below the connecting ring to position the connecting ring, thereby greatly improving the stability of the push rod during rotation and the accuracy of transmission.

[0022] During the rotation of the push rod, the rollers on the two mounting seats will also rotate when the connecting ring rotates. This structure not only reduces the friction between the rollers and the connecting ring, thereby increasing the service life of the components, but also enables the connecting ring to rotate more smoothly.

[0023] In the above-mentioned thread trimming device of a flat sewing machine, a swingable lifting and pressing shaft is provided on the casing, a presser foot lifting assembly is connected to the lifting and pressing shaft, and a cam capable of pushing the lifting and pressing shaft to swing is provided on the upper end of the output shaft of the motor.

[0024] The motor's output shaft is arranged vertically, with its upper end extending from the top of the motor housing and its lower end extending from the bottom. After the sewing machine completes sewing, the electronic control system sends a signal to the motor, causing it to rotate clockwise. This causes the pin to rotate along with the motor's output shaft, which in turn drives the push rod to rotate, thus trimming the thread. Once the thread is trimmed, the electronic control system controls the motor to rotate counterclockwise, causing the cam to swing the presser foot lifter assembly, which in turn lifts the presser foot. At this point, the pin is separated from the push rod, preventing interference. This structure allows both thread trimming and presser foot lifting to be achieved with a single motor, significantly simplifying the device's structure.

[0025] As an embodiment, the motor is a stepper motor.

[0026] In the above-mentioned thread trimming device of a stretch sewing machine, a crank is installed on the lifting and pressing shaft, and the cam includes a frustum-shaped conical portion, and the outer side of the conical portion has a frustum-shaped arc portion, and the arc portion gradually protrudes outward from the side wall of the conical portion, and the crank rests on the side wall of the cam.

[0027] When trimming the thread, the motor rotates clockwise, and the motor's output shaft drives the cam to rotate. At this point, the crank contacts the arc portion of the cam, and the presser foot lift shaft does not swing. When lifting the presser foot, the motor rotates counterclockwise, and the crank contacts the arc portion of the cam, which gradually protrudes outward. The rotating arc portion pushes the presser foot lift shaft to swing, and the presser foot lift shaft drives the presser foot of the presser foot lift assembly to lift the presser foot. This structure uses a single motor to achieve both thread trimming and presser foot lifting, and the functions of thread trimming and presser foot lifting do not affect each other.

[0028] The conical portion and the arc portion are both in the shape of a frustum, and both are structures that are larger at the top and smaller at the bottom. When the crank rests on the cam, the two are in close contact, preventing the crank from separating from the cam and ensuring the stability of the transmission.

[0029] In the above-mentioned thread trimming device of the interlock sewing machine, a ball is mounted on the crank, and the ball abuts against the side wall of the cam.

[0030] The crank is pressed against the cam through the ball, and the ball is smoother, which can reduce the friction with the cam during transmission. The conical part and the arc part of the cam are both frustum-shaped, and both are larger at the top and smaller at the bottom. When the ball presses against the conical part or the arc part of the cam, it can prevent the ball from separating from the cam, thereby ensuring the stability of the transmission.

[0031] In the above-mentioned thread trimming device of a flat sewing machine, the presser foot lifting assembly includes a connecting rod four connected to the presser lifting shaft, the connecting rod four is connected to a connecting rod five, the connecting rod five is installed with a clamping rod, and the bottom of the clamping rod is installed with a presser foot.

[0032] When the presser foot is lifted, the motor rotates counterclockwise, and the output shaft of the motor drives the cam to rotate. The crank contacts the arc part of the cam, and the arc part gradually protrudes outward. The rotating arc part pushes the lifting and pressing shaft to swing, and the lifting and pressing shaft drives the clamping rod to lift through connecting rod four and connecting rod five, and the presser foot is lifted accordingly, realizing the presser foot lifting.

[0033] The present invention also provides a flat sewing machine, comprising any one of the above-mentioned thread trimming devices.

[0034] Compared with the prior art, the advantages of the present invention are as follows:

[0035] 1. This thread trimming device drives the push rod to rotate through the pin shaft, and the push rod can drive the movable knife to move through the connecting rod assembly, so as to facilitate automatic thread trimming.

[0036] 2. This thread trimming device uses one motor to achieve thread trimming and presser foot lifting, which greatly simplifies the structure of the device, and the functions of thread trimming and presser foot lifting do not affect each other. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the thread trimming device installed on the casing;

[0038] Figure 2 It is a structural diagram of the thread trimming device;

[0039] Figure 3 It is a schematic diagram of the connection between the motor, the push rod and the cam;

[0040] Figure 4 It is a schematic diagram of the structure of the push rod;

[0041] Figure 5 1 is a schematic structural diagram of the positioning plate;

[0042] Figure 6 It is a structural diagram of positioning disk 2;

[0043] Figure 7 It is a structural diagram of the mounting base;

[0044] Figure 8 It is a structural diagram of the cam.

[0045] In the figure: 1 casing, 2 motor, 3 fixed knife, 4 movable knife, 5 connecting rod assembly, 6 output shaft, 7 pin shaft, 8 push rod, 9 protrusion, 10 mounting plate, 11 movable knife holder, 12 connecting rod one, 13 connecting rod two, 14 connecting rod three, 15 rocker arm, 16 mounting block, 17 mounting groove, 18 slide groove, 19 spring, 20 slider, 21 groove, 22 positioning plate one, 23 positioning plate two, 24 connecting ring, 25 accommodating groove, 26 mounting seat, 27 roller, 28 lifting and pressing shaft, 29 presser foot lifting assembly, 30 cam, 31 crank, 32 conical portion, 33 arc portion, 34 ball, 35 connecting rod four, 36 connecting rod five, 37 clamping rod, 38 connecting block. DETAILED DESCRIPTION

[0046] The following are specific embodiments of the present invention, and the technical solutions of the present invention are further described in conjunction with the accompanying drawings, but the present invention is not limited to these embodiments.

[0047] like Figure 1-3 As shown, the interlock sewing machine includes a casing 1, a thread trimming device includes a motor 2, a fixed knife 3, a movable knife 4 and a connecting rod assembly 5 for driving the movable knife 4 to move, a pin shaft 7 and a push rod 8 are provided at the lower end of the output shaft 6 of the motor 2, one end of the push rod 8 has a protrusion 9 and the end of the push rod 8 is rotatably connected to the lower end of the output shaft 6 of the motor 2, the other end of the push rod 8 is connected to the connecting rod assembly 5, the pin shaft 7 can abut against the protrusion 9 and push the push rod 8 to swing.

[0048] Its working principle is: in this thread trimming device, one end of the push rod 8 is sleeved on the lower end of the output shaft 6 of the motor 2 and can rotate. When the motor 2 rotates, the pin shaft 7 rotates with the output shaft 6. When the pin shaft 7 abuts against the protrusion 9 of the push rod 8, the pin shaft 7 pushes the push rod 8 to rotate, and the other end of the push rod 8 drives the connecting rod assembly 5 to move. The connecting rod assembly 5 drives the movable knife 4 to move, and the movable knife 4 moves relative to the fixed knife 3 to complete the thread trimming.

[0049] The thread trimming device drives the push rod 8 to rotate through the pin shaft 7, and the push rod 8 can drive the movable knife 4 to move through the connecting rod assembly 5, so as to conveniently perform automatic thread trimming.

[0050] like Figure 1 and 2 As shown, in this embodiment, a mounting plate 10 is provided on the casing 1, and a movable moving tool holder 11 is provided on the mounting plate 10, and the connecting rod assembly 5 includes a connecting rod 12, one end of the connecting rod 12 is hinged to one end of the push rod 8, and the other end of the connecting rod 12 is connected to a connecting rod 2 13, one end of the connecting rod 2 13 is hinged to a connecting rod 3 14, and one end of the connecting rod 3 14 is hinged to a rocker arm 15, the middle part of the rocker arm 15 is hinged to the mounting plate 10, and one end of the rocker arm 15 is hinged to the moving tool holder 11, a moving knife 4 is installed on the moving tool holder 11, and a fixed knife 3 is installed on the mounting plate 10, and the moving knife 4 is abutted against the fixed knife 3.

[0051] Connecting rod 2 13 is movably connected to the casing 1. When the motor 2 rotates, the pin shaft 7 pushes the push rod 8 to rotate, the push rod 8 drives connecting rod 12 to move, the connecting rod 12 drives connecting rod 2 13 to move, the connecting rod 2 13 drives connecting rod 3 14 to swing, the connecting rod 3 14 drives the rocker arm 15 to swing, the rocker arm 15 swings and drives the movable knife holder 11 to move, the movable knife 4 moves with the movable knife holder 11, and the movable knife 4 moves relative to the fixed knife 3 to complete the thread trimming.

[0052] As an embodiment, the fixed knife 3 is installed on the mounting plate 10 through the fixed knife holder, and the connecting rod 12 and the connecting rod 2 13 are connected through the connecting block 38. The connecting block 38 is connected to one end of the connecting rod 12, and one end of the connecting rod 2 13 is connected to the connecting block 38.

[0053] like Figure 2 As shown, in this embodiment, a mounting block 16 is fixed to the housing 1, a mounting groove 17 is provided on the mounting block 16, a slide groove 18 is provided on the bottom wall of the mounting groove 17, the connecting rod 13 is slidably connected to the mounting block 16, a spring 19 and a slider 20 are sleeved on the connecting rod 13, the upper half of the slider 20 and the spring 19 are located in the mounting groove 17, one end of the spring 19 rests on the groove wall of the mounting groove 17, the other end of the spring 19 rests on the upper half of the slider 20, and the lower half of the slider 20 is slidably connected in the slide groove 18.

[0054] The upper half of the slider 20 is fixed on the connecting rod 2 13. When the motor 2 rotates clockwise, the push rod 8 drives the connecting rod 2 13 to move through the connecting rod 1 12 (at this time the spring 19 is gradually in a compressed state), and the connecting rod 2 13 drives the movable knife 4 to move relative to the fixed knife 3 through the connecting rod 3 14 and the rocker arm 15 to complete the thread trimming. After that, the motor 2 rotates counterclockwise to reset, and the spring 19 pushes the connecting rod 2 13 to move in the opposite direction under the action of the restoring force, so that the movable knife 4 is automatically reset, thereby improving the convenience of operation.

[0055] During the movement of the connecting rod 2 13 , the lower half of the slider 20 moves in the slide groove 18 . The slider 20 and the slide groove 18 form a guide structure, which greatly improves the stability of the connecting rod 2 13 during movement and also improves the accuracy of the transmission.

[0056] like Figure 3 、 4 As shown in FIG5 , in this embodiment, the pin shaft 7 is cylindrical, and the protrusion 9 has an arc-shaped groove 21 , and the pin shaft 7 can abut against the inner wall of the groove 21 .

[0057] One side of the groove 21 is open. After the pin 7 rotates into the groove 21, it abuts against the inner wall of the groove 21 and pushes the push rod 8 to rotate. This structure allows the pin 7 to more fully contact the protrusion 9 of the push rod 8, ensuring transmission stability. During transmission, the pin 7 is located in the groove 21, ensuring close contact between the pin 7 and the protrusion 9, preventing the two from separating.

[0058] like Figure 3 and 5 As shown, in this embodiment, a positioning plate 22 is sleeved and fixed on the lower end of the output shaft 6 of the motor 2, and the pin shaft 7 is arranged on one side of the positioning plate 22.

[0059] The pin shaft 7 can be a part of the positioning plate 1 22 , that is, the two are an integrated structure, and the pin shaft 7 can also be detachably fixed on the positioning plate 1 22 .

[0060] like Figure 3 、 5 As shown in , 6 and 7, in this embodiment, the lower end of the output shaft 6 of the motor 2 is also sleeved and fixed with a positioning disk 23, and the upper end of the push rod 8 has a connecting ring 24, which is sleeved on the lower end of the output shaft 6 of the motor 2, and the bottom of the positioning disk 1 22 and the top of the positioning disk 2 23 are respectively provided with a receiving groove 25, and a mounting seat 26 is respectively installed in the accommodating groove 25. The mounting seat 26 is sleeved on the output shaft 6 of the motor 2, and a rotatable roller 27 is respectively provided on the mounting seat 26. The roller 27 is distributed along the circumference of the corresponding mounting seat 26 and extends from the inside to the outside. The connecting ring 24 is located between the positioning disk 1 22 and the positioning disk 2 23, and the top and bottom of the connecting ring 24 respectively abut against the roller 27 of each mounting seat 26.

[0061] In this structure, the rollers 27 on the two mounting seats 26 are respectively located above and below the connecting ring 24 to position the connecting ring 24, thereby greatly improving the stability of the push rod 8 during rotation and the accuracy of transmission.

[0062] During the rotation of the push rod 8, the rollers 27 on the two mounting seats 26 will also rotate when the connecting ring 24 rotates. This structure not only reduces the friction between the rollers 27 and the connecting ring 24, thereby increasing the service life of the components, but also enables the connecting ring 24 to rotate more smoothly.

[0063] like Figure 2 As shown, in this embodiment, a swingable lifting and pressing shaft 28 is provided on the casing 1, a presser foot lifting assembly 29 is connected to the lifting and pressing shaft 28, and a cam 30 that can push the lifting and pressing shaft 28 to swing is provided on the upper end of the output shaft 6 of the motor 2.

[0064] The output shaft 6 of motor 2 is arranged vertically, with its upper end extending from the top of the motor housing and its lower end extending from the bottom. After the sewing machine completes sewing, the electronic control system sends a signal to motor 2, causing it to rotate clockwise. This causes pin 7 to rotate along with the output shaft 6 of motor 2, which in turn rotates push rod 8, thereby trimming the thread. After thread trimming is complete, the electronic control system controls motor 2 to rotate counterclockwise, resetting the thread trimming mechanism. The cam 30 pushes the presser foot lifter 28 to swing, which in turn drives the presser foot lifter assembly 29 to lift the presser foot. At this point, pin 7 and push rod 8 are separated, preventing interference. This structure allows the same motor 2 to achieve both thread trimming and presser foot lifting, significantly simplifying the device's structure.

[0065] As an embodiment, the motor 2 is a stepper motor 2 .

[0066] like Figure 2 and 8 As shown, in this embodiment, a crank 31 is installed on the lifting shaft 28, and the cam 30 includes a cone-shaped conical portion 32, and the outer side of the cone-shaped portion 32 has a cone-shaped arc portion 33, and the arc portion 33 gradually protrudes outward from the side wall of the cone portion 32, and the crank 31 rests on the side wall of the cam 30.

[0067] When trimming the thread, the motor 2 rotates clockwise, and the output shaft 6 of the motor 2 drives the cam 30 to rotate. At this time, the crank 31 contacts the conical portion 32 of the cam 30, and the presser foot lifting shaft 28 does not swing. When lifting the presser foot, the motor 2 rotates counterclockwise. At this time, the crank 31 contacts the arc portion 33 of the cam 30, and the arc portion 33 gradually protrudes outward. The rotating arc portion 33 pushes the presser foot lifting shaft 28 to swing, and the presser foot lifting shaft 28 drives the presser foot of the presser foot lifting assembly 29 to lift, thus achieving presser foot lifting. This structure uses the same motor 2 to achieve both thread trimming and presser foot lifting, and the functions of thread trimming and presser foot lifting do not affect each other.

[0068] The conical portion 32 and the arc portion 33 are both in the shape of a frustum, and both are structures that are larger at the top and smaller at the bottom. When the crank 31 rests on the cam 30, the two are in close contact, preventing the crank 31 from separating from the cam 30 and ensuring the stability of the transmission.

[0069] like Figure 3 As shown, in this embodiment, a ball 34 is mounted on the crank 31 , and the ball 34 abuts against the side wall of the cam 30 .

[0070] The crank 31 is pressed against the cam 30 through the ball 34. The ball 34 is smoother and can reduce the friction with the cam 30 during transmission. The conical portion 32 and the arc portion 33 of the cam 30 are both frustum-shaped, and both are larger at the top and smaller at the bottom. When the ball 34 is pressed against the conical portion 32 or the arc portion 33 of the cam 30, it can prevent the ball 34 from separating from the cam 30, thereby ensuring the stability of the transmission.

[0071] like Figure 2 As shown, in this embodiment, the presser foot lifting assembly 29 includes a connecting rod 4 35 connected to the presser shaft 28, a connecting rod 5 36 is connected to the connecting rod 4 35, a clamping rod 37 is installed on the connecting rod 5 36, and a presser foot (not shown) is installed at the bottom of the clamping rod 37.

[0072] When lifting the presser foot, the motor 2 rotates counterclockwise, and the output shaft 6 of the motor 2 drives the cam 30 to rotate. The crank 31 contacts the arc portion 33 of the cam 30, and the arc portion 33 gradually protrudes outward. The rotating arc portion 33 pushes the lifting and pressing shaft 28 to swing, and the lifting and pressing shaft 28 drives the clamping rod 37 to lift through the connecting rod four 35 and the connecting rod five 36, and the presser foot is lifted accordingly, thereby realizing the presser foot lifting.

[0073] The present invention also provides a flat sewing machine, which includes any one of the above-mentioned thread trimming devices.

[0074] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A thread trimming device for a flat sewing machine, the flat sewing machine comprising a housing (1), the thread trimming device comprising a motor (2), a fixed knife (3), a movable knife (4) and a connecting rod assembly (5) for driving the movable knife (4) to move, characterized in that: The lower end of the output shaft (6) of the motor (2) is provided with a pin shaft (7) and a push rod (8); one end of the push rod (8) is provided with a protrusion (9) and the end of the push rod (8) is rotatably connected to the lower end of the output shaft (6) of the motor (2); the other end of the push rod (8) is connected to the connecting rod assembly (5); the pin shaft (7) can abut against the protrusion (9) and push the push rod (8) to swing.

2. The thread trimming device of a flat seam sewing machine according to claim 1, characterized in that: The housing (1) is provided with a mounting plate (10), and a movable moving knife (4) frame is provided on the mounting plate (10). The connecting rod assembly (5) includes a connecting rod 1 (12), one end of the connecting rod 1 (12) is hinged to one end of the push rod (8), and the other end of the connecting rod 1 (12) is connected to a connecting rod 2 (13), one end of the connecting rod 2 (13) is hinged to a connecting rod 3 (14), and one end of the connecting rod 3 (14) is hinged to a rocker arm (15), the middle part of the rocker arm (15) is hinged to the mounting plate (10), and one end of the rocker arm (15) is hinged to the moving knife (4) frame. The moving knife (4) is installed on the moving knife (4) frame, and the fixed knife (3) is installed on the mounting plate (10). The moving knife (4) is in contact with the fixed knife (3).

3. The thread trimming device of a flat seam sewing machine according to claim 2, characterized in that: A mounting block (16) is fixed on the housing (1), a mounting groove (17) is provided on the mounting block (16), a sliding groove (18) is provided on the bottom wall of the mounting groove (17), the second connecting rod (13) is slidably connected to the mounting block (16), a spring (19) and a slider (20) are sleeved on the second connecting rod (13), the upper half of the slider (20) and the spring (19) are located in the mounting groove (17), one end of the spring (19) rests on the groove wall of the mounting groove (17), the other end of the spring (19) rests on the upper half of the slider (20), and the lower half of the slider (20) is slidably connected to the sliding groove (18).

4. The thread trimming device of a flat seam sewing machine according to claim 1, characterized in that: The pin shaft (7) is cylindrical, the protruding portion (9) has an arc-shaped groove (21), and the pin shaft (7) can abut against the inner wall of the groove (21).

5. A thread trimming device for a flat seam sewing machine according to claim 1, 2, 3 or 4, characterized in that: A positioning disc (22) is sleeved and fixed on the lower end of the output shaft (6) of the motor (2), and the pin shaft (7) is arranged on one side of the positioning disc (22).

6. The thread trimming device of a flat seam sewing machine according to claim 5, characterized in that: The lower end of the output shaft (6) of the motor (2) is also sleeved and fixed with a positioning disk 2 (23), and the upper end of the push rod (8) has a connecting ring (24), which is sleeved on the lower end of the output shaft (6) of the motor (2), and the bottom of the positioning disk 1 (22) and the top of the positioning disk 2 (23) are respectively provided with a receiving groove (25), and a mounting seat (26) is respectively installed in the receiving groove (25), and the mounting seat (26) is sleeved on the output shaft (6) of the motor (2), and a rotatable roller (27) is respectively provided on the mounting seat (26), and the roller (27) is distributed along the circumference of the corresponding mounting seat (26) and extends from the inside to the outside. The connecting ring (24) is located between the positioning disk 1 (22) and the positioning disk 2 (23), and the top and bottom of the connecting ring (24) respectively abut against the roller (27) of each mounting seat (26).

7. A thread trimming device for a flat seam sewing machine according to claim 1, 2, 3 or 4, characterized in that: The housing (1) is provided with a swingable lifting and pressing shaft (28), a presser foot lifting assembly (29) is connected to the lifting and pressing shaft (28), and the upper end of the output shaft (6) of the motor (2) is provided with a cam (30) capable of pushing the lifting and pressing shaft (28) to swing.

8. The thread trimming device of a flat seam sewing machine according to claim 7, characterized in that: A crank (31) is installed on the lifting shaft (28), and the cam (30) includes a cone-shaped conical portion (32), and the outer side of the cone-shaped conical portion (32) has a cone-shaped arc portion (33), and the arc portion (33) gradually protrudes outward from the side wall of the cone portion (32), and the crank (31) rests on the side wall of the cam (30).

9. The thread trimming device of a flat seam sewing machine according to claim 8, characterized in that: A ball (34) is mounted on the crank (31), and the ball (34) abuts against the side wall of the cam (30).

10. A flat seam sewing machine, characterized in that: The interlock sewing machine includes a thread cutting device according to any one of claims 1 to 9.

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