A sewing machine

Abstract

The present invention belongs to the technical field of sewing equipment, and particularly refers to a sewing machine; a thread trimming drive mechanism includes a thread trimming cam and a lifting member, a thread trimming drive block is provided at the upper end of the lifting member, a thread trimming roller is installed on the thread trimming drive block, and a thread trimming roller abutting the cam surface of the thread trimming cam is provided, and a movable knife seat is provided at the lower end of the lifting member, and the movable knife seat includes an upper mounting seat and a lower adjustment seat, the upper mounting seat is fixedly connected to the lower end of the lifting member, and the lower adjustment seat is connected to the movable knife through a linear adjustment mechanism, the linear adjustment mechanism drives the movable knife to move longitudinally to adjust the distance between the movable knife and the fixed knife, and the lower adjustment seat is connected to the upper mounting seat through a rotation adjustment mechanism, and the rotation adjustment mechanism drives the lower adjustment seat to rotate to adjust the inclination angles of the movable knife and the fixed knife; the present invention realizes the distance and inclination angle between the movable knife and the fixed knife through linear adjustment and rotation adjustment, adapts to different wire thicknesses or wear conditions, and prevents the occurrence of wire jams or uncut phenomena.

Description

Technical Field

[0001] The invention belongs to the technical field of sewing equipment, in particular to a sewing machine. Background Art

[0002] A sewing machine uses one or more sewing threads to create one or more stitches on a material, interweaving or stitching one or more layers of material. Currently, most sewing machines are equipped with an automatic presser foot lifter. This controls the lifting and lowering of the presser foot to thread the sewing thread through the material, achieving the desired stitch.

[0003] Sewing machines include a presser foot lifter and a thread trimmer. Research is increasingly underway on structures that use the same drive source to drive both the presser foot lifter and the thread trimmer. The thread trimmer mechanism of a sewing machine typically includes a movable knife and a fixed knife. The movable knife is driven by the drive source and works in conjunction with the fixed knife to complete the thread cutting process. During use, the movable and fixed knives may experience wear or assembly errors, leading to reduced thread cutting effectiveness. The movable knife in traditional thread trimmer mechanisms is typically fixed, making fine adjustment difficult. This can lead to incomplete thread cutting or thread jamming, compromising sewing quality. Summary of the Invention

[0004] The object of the present invention is to provide a sewing machine capable of adjusting the position of a movable knife and improving thread trimming performance.

[0005] The present invention is achieved in that:

[0006] A sewing machine comprises a driving source, a thread trimming mechanism and a thread trimming driving mechanism, a presser foot lifting mechanism and a presser foot lifting driving mechanism, the driving source having a first rotating shaft and a second rotating shaft, the thread trimming driving mechanism comprising a thread trimming cam fixedly arranged on the first rotating shaft, a lifting member slidably connected to the casing, the upper end of the lifting member being provided with a thread trimming driving block, the thread trimming driving block being provided with a thread trimming rolling member abutting against the cam surface of the thread trimming cam, the lower end of the lifting member being provided with a movable knife seat, the movable knife seat comprising an upper mounting seat and a lower adjusting seat, the upper mounting seat being fixedly connected to the lower end of the lifting member, the lower adjusting seat being connected to the movable knife via a linear adjusting mechanism, the linear adjusting mechanism driving the movable knife to move longitudinally to adjust the distance between the movable knife and the fixed knife, the lower adjusting seat being connected to the upper mounting seat via a rotating adjusting mechanism, and the rotating adjusting mechanism driving the lower adjusting seat to rotate to adjust the inclination angle of the movable knife and the fixed knife.

[0007] In the above-mentioned sewing machine, the presser foot lifting driving mechanism includes a presser foot lifting cam fixed on the second rotating shaft, a presser foot lifting crank with one end rotatably set on the casing or the mounting seat, the other end of the presser foot lifting crank is in contact with the cam surface of the presser foot lifting cam through a presser foot lifting roller, and a presser foot lifting crank connecting plate is rotatably connected to the position between the two ends of the presser foot lifting crank, and the presser foot lifting crank connecting plate is also rotatably connected to one end of the presser foot lifting lever, and the other end of the presser foot lifting lever is fixedly connected to the driving lever of the presser foot lifting driving mechanism.

[0008] In the above-mentioned sewing machine, the linear adjustment mechanism includes a fixed shaft, one end of the fixed shaft is fixedly connected to the movable knife, and the other end is movably connected to the lower adjustment seat, and an avoidance groove is provided on the lower adjustment seat or the lower adjustment seat and the upper mounting seat, and a limiting member is provided on the fixed shaft near the movable knife in the avoidance groove, and a reset member is provided between the limiting member and the side wall of the avoidance groove away from the end of the movable knife, and an adjusting member is screwed on the end of the fixed shaft away from the movable knife, and the adjusting member drives the fixed shaft to move along its axis to drive the movable knife to adjust the distance between it and the fixed knife.

[0009] In the above-mentioned sewing machine, the movable knife is installed on the movable knife bracket, and a screw portion is provided at one end of the fixed shaft, and a step surface is formed between the screw portion and the fixed shaft. A through hole is provided on the movable knife bracket, and the screw portion passes through the through hole and is screwed with a locking nut to realize a fixed connection between the fixed shaft and the movable knife bracket.

[0010] In the above-mentioned sewing machine, a second waist-shaped hole is further provided on the movable knife bracket, and the axial screw passes through the second waist-shaped hole and is screwed to the lower adjustment seat, and the axis of the axial screw is arranged parallel to the fixed axis.

[0011] In the above-mentioned sewing machine, the rotation adjustment mechanism includes a circular hole and a first waist-shaped hole arranged at intervals on the lower adjustment seat and parallel to the axis direction of the fixed shaft. The lower adjustment seat is fixedly connected to the upper mounting seat by a first screw passing through the circular hole, and is fixedly connected to the upper mounting seat by a second screw passing through the first waist-shaped hole. By adjusting the position of the second screw in the first waist-shaped hole, the lower adjustment seat can be driven to rotate around the axis of the first screw, driving the movable knife bracket and the movable knife to rotate around the axis of the first screw to adjust the inclination angle between the movable knife and the fixed knife.

[0012] In the above-mentioned sewing machine, an adjusting screw is provided on one side wall of the upper mounting seat, and a limiting slot is provided on the lower adjusting seat. The adjusting screw has a head that can extend into the limiting slot and abut against the inner side wall of the limiting slot, and a screw threadedly connected to the upper mounting seat. The inner side wall of the limiting slot is parallel to the axis of the fixed shaft. By rotating the adjusting screw and loosening the second screw, the lower adjusting seat can be driven to rotate around the axis of the first screw.

[0013] In the above-mentioned sewing machine, it also includes a thread loosening mechanism, a thread loosening hole is provided in the portion between the two ends of the driving lever, and a thread loosening crank of the thread loosening mechanism has a thread loosening driving pin that passes through the thread loosening hole.

[0014] In the above-mentioned sewing machine, it also includes a rear tug mechanism, the other end of the driving lever is also connected to one end of the rear tug lifting and pressing connecting rod, the other end of the rear tug lifting and pressing connecting rod is connected to the lifting and pressing connecting rod through a long connecting rod and a rear tug crank, and the lifting and pressing connecting rod is connected to the pressure rod of the rear tug mechanism through a block.

[0015] In the above-mentioned sewing machine, the lifting member is slidably connected to the slider, and the slider is fixed on the mounting seat.

[0016] The advantages of the present invention compared to the prior art are:

[0017] The present invention realizes precise adjustment of the spacing and inclination angle between the movable knife and the fixed knife through linear adjustment and rotational adjustment, and can flexibly adjust the bite gap and contact angle of the movable knife and the fixed knife to ensure optimal shearing force, adapt to different wire thicknesses or wear conditions, extend the tool life, and prevent wire jamming or uncut wires. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is one of the three-dimensional schematic diagrams of the present invention;

[0019] Figure 2 This is the second stereoscopic schematic diagram of the present invention;

[0020] Figure 3 This is one of the schematic diagrams of the structure of a driving source driving the presser foot lifting, thread trimming, thread loosening, and rear tug wheel lifting of the present invention;

[0021] Figure 4 This is a second schematic diagram of a structure of a driving source driving presser foot lifting, thread trimming, thread loosening, and rear tug wheel lifting according to the present invention;

[0022] Figure 5 is a schematic diagram of the thread trimming drive mechanism of the present invention;

[0023] Figure 6 This is one of the schematic diagrams of the presser foot lifting, thread loosening, and rear tug wheel lifting linkage structure of the present invention;

[0024] Figure 7 This is the second schematic diagram of the presser foot lifting, thread loosening, and rear tug wheel lifting linkage structure of the present invention;

[0025] Figure 8 Schematic diagram of the presser foot lifting drive mechanism of the present invention;

[0026] Figure 9 is a schematic diagram of the thread trimming cam of the present invention;

[0027] Figure 10 2 is a schematic diagram of a presser foot lifting cam of the present invention;

[0028] Figure 11 This is one of the schematic diagrams of the movable knife of the present invention being installed on the movable knife seat through the movable knife bracket;

[0029] Figure 12 This is the second schematic diagram of the movable knife of the present invention being installed on the movable knife seat through the movable knife bracket;

[0030] Figure 13 yes Figure 12 A top view of

[0031] Figure 14 yes Figure 13 AA section view;

[0032] Figure 15 is a schematic diagram of the movable knife support of the present invention;

[0033] Figure 16 It is a schematic diagram of the lower adjustment seat of the present invention.

[0034] In the figure: 1. Drive source; 2. Casing; 3. Mounting seat; 4. Thread trimmer cam; 5. Lifting member; 6. Thread trimmer drive block; 7. Moving knife seat; 8. Upper mounting seat; 9. Lower adjustment seat; 10. Moving knife; 11. Fixed knife; 12. Slider; 13. Linear guide mounting seat; 14. Thread trimmer idle stroke section; 15. Thread trimmer drive section; 16. Presser foot lift cam; 17. Presser foot lift crank; 18. Presser foot lift roller; 19. Presser foot lift crank connecting plate; 20. Presser foot lift lever; 21. Drive lever; 22. Presser foot lift Foot idle stroke section; 23. Presser foot lifting and pressing drive section; 24. Fixed shaft; 25. Limiting part; 26. Reset part; 27. Adjusting part; 28. Moving knife bracket; 29. ​​Circular hole; 30. First waist-shaped hole; 31. Adjusting screw; 32. Limiting groove; 33. Second waist-shaped hole; 34. Third waist-shaped hole; 35. Wire release hole; 36. Wire release crank; 37. Wire release driving pin; 38. Rear tugboat lifting and pressing connecting rod; 39. Long connecting rod; 40. Rear tugboat crank; 41. Lifting and pressing connecting rod; 42. Block; 43. Press rod. DETAILED DESCRIPTION

[0035] The present invention will be further described below with specific embodiments:

[0036] like Figures 1-16 As shown, the present invention provides a sewing machine, which can drive a presser foot lifting drive mechanism and a thread trimming drive mechanism through a driving source to respectively realize the actions of the presser foot lifting mechanism and the thread trimming mechanism.

[0037] Specifically, the drive source 1 includes a first rotating shaft and a second rotating shaft. In this embodiment, the drive source 1 utilizes a double-ended motor, with the first and second rotating shafts extending from opposite ends of the motor. To rationally allocate space outside the housing 2 and ensure a proper layout of the various mechanisms, the drive source 1 of the present invention is mounted on a mounting base 3, which is fixedly mounted on the housing 2. The mounting base of this embodiment includes a vertical plate and a horizontal plate, the horizontal plate being fixedly connected to the housing 2, and the drive source 1 being mounted on the vertical plate via a drive source bracket. The vertical plate is spaced apart from the corresponding outer sidewalls of the housing 2.

[0038] Specifically, the thread trimming drive mechanism includes a thread trimming cam 4 that rotates with the first rotating shaft, and a lifting member 5 that is slidably mounted on the housing 2. A thread trimming drive block 6 is provided at the upper end of the lifting member 5. A thread trimming roller is mounted on the thread trimming drive block 6 and abuts against the cam surface of the thread trimming cam 4. The thread trimming roller can be a bearing or a roller. A movable knife seat 7 is provided at the lower end of the lifting member 5. The movable knife seat 7 includes an upper mounting seat 8 and a lower adjustment seat 9. The upper mounting seat 8 is fixedly connected to the lower end of the lifting member 5. The lower adjustment seat 9 is connected to the movable knife 10 via a linear adjustment mechanism. The linear adjustment mechanism drives the movable knife 10 to move longitudinally to adjust the distance between the movable knife 10 and the fixed knife 11. The lower adjustment seat 9 is connected to the upper mounting seat 8 via a rotation adjustment mechanism. The rotation adjustment mechanism drives the lower adjustment seat 9 to rotate to adjust the inclination angle of the movable knife 10 and the fixed knife 11.

[0039] The present invention realizes precise adjustment of the spacing and inclination angle between the movable knife 10 and the fixed knife 11 through linear adjustment and rotational adjustment, and can flexibly adjust the bite gap and contact angle between the movable knife 10 and the fixed knife 11 to ensure optimal shearing force, adapt to different wire thicknesses or wear conditions, extend the tool life, and prevent wire jamming or uncut wires.

[0040] In this embodiment, the lifting member 5 is a lifting guide rail, equipped with a slider 12. Slider 12 is secured to the housing 2 or the aforementioned mounting base 3 via a linear guide rail mounting base 13. The lifting member 5 moves up and down along slider 12, driving the movable blade 10 to move up and down, engaging the fixed blade 11. Furthermore, the structure of the lifting guide rail and slider 12 can also be replaced by an equivalent structure of a guide sleeve and guide rod. The present invention, combined with the rigid guidance of the lifting member 5, ensures a stable motion trajectory for the movable blade 10.

[0041] It should be noted that the thread trimming cam 4 of the present invention comprises a wheel with a spiral groove formed on one side. This groove includes a thread trimming idle travel section 14 and a thread trimming drive section 15. The adjacent sections of the thread trimming idle travel section 14 and the thread trimming drive section 15 have a smooth transition. The distance from the thread trimming drive section 15 to the center of the thread trimming cam 4 gradually increases from the end connected to the thread trimming idle travel section 14. The thread trimming roller is disposed within the spiral groove and rolls along the spiral groove.

[0042] As described above, the presser foot lifting drive mechanism of the present invention includes a presser foot lifting cam 16 that rotates with the second rotating shaft, a presser foot lifting crank 17 whose one end is rotatably mounted on the housing 2 or the mounting base 3, and the other end of the presser foot lifting crank 17 abuts against the outer peripheral surface of the presser foot lifting cam 16 via a presser foot lifting roller 18. The presser foot lifting roller 18 can be a bearing or a roller. A presser foot lifting crank connecting plate 19 is rotatably connected to the portion between the two ends of the presser foot lifting crank 17. The presser foot lifting crank connecting plate 19 is also rotatably connected to one end of a presser foot lifting lever 20, and the other end of the presser foot lifting lever 20 is fixedly connected to a driving lever 21 of the presser foot lifting drive mechanism.

[0043] The presser foot lifting cam 16 of the present invention includes a presser foot lifting idle stroke section 22 and a presser foot lifting driving section 23. One end of the presser foot lifting driving section 23 is connected to the presser foot lifting idle stroke section 22, and the other end of the presser foot lifting driving section 23 is connected to the other end of the presser foot lifting idle stroke section 22 via a transition section. The distance from the presser foot lifting driving section 23 to the center of the presser foot lifting cam 16 gradually increases from the end connected to the presser foot lifting idle stroke section 22 to control the presser foot to different heights, which is suitable for sewing fabrics of different thicknesses.

[0044] When the presser foot is lifted, the presser foot lifting roller 18 rolls in the presser foot lifting drive section 23, and the thread trimming roller rolls in the thread trimming idle stroke section 14. Conversely, when trimming the thread, the thread trimming roller rolls in the thread trimming drive section 15, and the presser foot lifting roller rolls in the presser foot lifting idle stroke section 22, and the two do not interfere with each other.

[0045] Furthermore, as one embodiment, the linear adjustment mechanism includes a fixed shaft 24, one end of which is fixedly connected to the movable blade 10 and the other end is movably connected to the lower adjustment seat 9. An escape groove is provided on the lower adjustment seat 9 or the lower adjustment seat 9 and the upper mounting seat 8. A limit member 25 is provided on the fixed shaft 24 in the escape groove near the movable blade 10. A reset member 26 is provided between the limit member 25 and the side wall of the escape groove away from the movable blade 10. An adjustment member 27 is screwed to the end of the fixed shaft 24 away from the movable blade 10. The adjustment member 27 drives the fixed shaft 24 to move along its axis to drive the movable blade 10 to adjust the distance between the movable blade 10 and the fixed blade 11. The limit member 25 is a retaining ring or a retaining spring, the reset member 26 is a spring or a spring, and the adjustment member 27 is an adjustment knob or an adjustment nut.

[0046] As another embodiment, the linear adjustment mechanism can adopt a gear rack adjustment structure, such as: processing a rack portion on the side of the fixed shaft, the rack portion extends beyond the lower adjustment seat, and a gear that engages with the rack is rotatably provided on the lower adjustment seat, and the rotating gear drives the fixed shaft to move.

[0047] It should be noted that the movable knife 10 described in the present invention is installed on the movable knife bracket 28, and a screw portion is provided at one end of the fixed shaft 24, and a step surface is formed between the screw portion and the fixed shaft 24. A through hole is provided on the movable knife bracket 28, and the screw portion passes through the through hole and is screwed with a locking nut to realize a fixed connection between the fixed shaft 24 and the movable knife bracket 28, thereby limiting the movable knife bracket 28 between the step surface and the locking nut.

[0048] In addition, as one embodiment, the rotation adjustment mechanism includes a circular hole 29 and a first waist-shaped hole 30 arranged at intervals on the lower adjustment seat 9 and arranged parallel to the axis of the fixed shaft 24. The lower adjustment seat 9 is fixedly connected to the upper mounting seat 8 by a first screw passing through the circular hole 29, and is fixedly connected to the upper mounting seat 8 by a second screw passing through the first waist-shaped hole 30. Adjusting the position of the second screw in the first waist-shaped hole 30 can drive the lower adjustment seat 9 to rotate around the axis of the first screw, driving the movable knife bracket 28 and the movable knife 10 to rotate around the axis of the first screw to adjust the inclination angle between the movable knife 10 and the fixed knife 11. By adjusting the inclination angle, the problem of blade misalignment caused by assembly error can be solved, so that the cutting edges of the movable knife 10 and the fixed knife 11 are completely aligned, thereby improving the smoothness of thread cutting.

[0049] For the convenience of adjustment, an adjusting screw 31 is provided on one side wall of the upper mounting seat 8, and a limiting slot 32 is provided on the lower adjusting seat 9. The adjusting screw 31 has a head that can extend into the limiting slot 32 and abut against the inner side wall of the limiting slot 32, and a screw threadedly connected to the upper mounting seat 8. The inner side wall of the limiting slot 32 is parallel to the axis of the fixed shaft 24. By rotating the adjusting screw 31 and loosening the second screw, the lower adjusting seat 9 can be driven to rotate around the axis of the first screw.

[0050] As another embodiment, the rotation adjustment mechanism adopts an eccentric shaft structure. Specifically, an eccentric screw is used to replace the first screw of the rotation adjustment mechanism, and adjustment can be achieved by rotating the screw head.

[0051] It should be noted that the present invention further provides a second waist-shaped hole 33 on the movable knife bracket 28. An axial screw passes through the second waist-shaped hole 33 and is screwed onto the lower adjustment seat 9. The axis of the axial screw is arranged parallel to the fixed axis 24. This arrangement allows the second waist-shaped hole 33 and the axial screw to allow small displacement of the movable knife bracket 28 when adjusting the inclination angle, avoiding structural interference. At the same time, it also prevents the movable knife bracket 28 from rotating about the fixed axis 24.

[0052] In addition, the present invention further provides third waist-shaped holes 34 on either side of the second waist-shaped hole 33 on the movable blade support 28. The movable blade 10 is fixedly connected to the movable blade support 28 via screws passing through the third waist-shaped holes 34. This arrangement further expands the adjustable range of the movable blade 10 position, adapting to different wire materials or cutting requirements, and enhancing the structural versatility.

[0053] The present invention also performs a thread loosening action while lifting the presser foot. Specifically, the structure of the present invention also includes a thread loosening mechanism, and a thread loosening hole 35 is provided in the portion between the two ends of the driving lever 21. The thread loosening crank 36 of the thread loosening mechanism has a thread loosening driving pin 37 that is inserted into the thread loosening hole 35.

[0054] Furthermore, the present invention can also lift the rear tug while lifting the presser foot and loosening the thread. Specifically, the present invention also includes a rear tug mechanism. The other end of the driving lever 21 is also connected to one end of the rear tug lifting and pressing link 38. The other end of the rear tug lifting and pressing link 38 is connected to the lifting and pressing link 41 through a long connecting rod 39 and a rear tug crank 40. The lifting and pressing link 41 is connected to the pressure rod 43 of the rear tug mechanism through a block 42. The rear tug mechanism is linked to the driving lever 21 of the presser foot, expanding the functional coverage of the single driving source 1.

[0055] The above embodiment is only one of the preferred embodiments of the present invention and is not intended to limit the scope of implementation of the present invention. Therefore, any equivalent changes made based on the shape, structure, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A sewing machine comprising a driving source (1), a thread trimming mechanism and a thread trimming driving mechanism, a presser foot lifting mechanism and a presser foot lifting driving mechanism, wherein the driving source (1) has a first rotating shaft and a second rotating shaft, and is characterized in that: The thread trimming drive mechanism comprises a thread trimming cam (4) fixed on the first rotating shaft, a lifting member (5) slidably connected to the housing (2), a thread trimming drive block (6) is provided on the upper end of the lifting member (5), a thread trimming roller abutting against the cam surface of the thread trimming cam (4) is installed on the thread trimming drive block (6), a movable knife seat (7) is provided at the lower end of the lifting member (5), the movable knife seat (7) comprises an upper mounting seat (8) and a lower adjustment seat (9), the upper mounting seat (8) is fixedly connected to the lower end of the lifting member (5), the lower adjustment seat (9) is connected to the movable knife (10) through a linear adjustment mechanism, the linear adjustment mechanism drives the movable knife (10) to move longitudinally to adjust the distance between the movable knife (10) and the fixed knife (11), the lower adjustment seat (9) is connected to the upper mounting seat (8) through a rotation adjustment mechanism, and the rotation adjustment mechanism drives the lower adjustment seat (9) to rotate to adjust the inclination angle of the movable knife (10) and the fixed knife (11); The rotation adjustment mechanism includes a circular hole (29) and a first waist-shaped hole (30) arranged on the lower adjustment seat (9) in a direction parallel to the axis of the fixed shaft (24) and spaced apart. The lower adjustment seat (9) is fixedly connected to the upper mounting seat (8) by a first screw passing through the circular hole (29), and is fixedly connected to the upper mounting seat (8) by a second screw passing through the first waist-shaped hole (30). By adjusting the position of the second screw in the first waist-shaped hole (30), the lower adjustment seat (9) can be driven to rotate around the axis of the first screw, thereby driving the movable knife bracket (28) and the movable knife (10) to rotate around the axis of the first screw to adjust the inclination angle between the movable knife (10) and the fixed knife (11); An adjusting screw (31) is provided on one side wall of the upper mounting seat (8), and a limiting slot (32) is provided on the lower adjusting seat (9). The adjusting screw (31) has a head that can extend into the limiting slot (32) and abut against the inner side wall of the limiting slot (32), and a screw that is screwed to the upper mounting seat (8). The inner side wall of the limiting slot (32) is parallel to the axis of the fixed shaft (24). By rotating the adjusting screw (31) and loosening the second screw, the lower adjusting seat (9) can be driven to rotate around the axis of the first screw.

2. A sewing machine according to claim 1, characterized in that: The presser foot lifting driving mechanism comprises a presser foot lifting cam (16) fixedly mounted on the second rotating shaft, a presser foot lifting crank (17) with one end rotatably mounted on the housing (2) or the mounting seat (3), the other end of the presser foot lifting crank (17) abutting against the cam surface of the presser foot lifting cam (16) via a presser foot lifting rolling member (18), a presser foot lifting crank connecting plate (19) rotatably connected to a portion between the two ends of the presser foot lifting crank (17), the presser foot lifting crank connecting plate (19) is also rotatably connected to one end of a presser foot lifting lever (20), and the other end of the presser foot lifting lever (20) is fixedly connected to a driving lever (21) of the presser foot lifting driving mechanism.

3. A sewing machine according to claim 1 or 2, characterized in that: The linear adjustment mechanism includes a fixed shaft (24), one end of the fixed shaft (24) is fixedly connected to the movable knife (10), and the other end is movably connected to the lower adjustment seat (9), and an avoidance groove is provided on the lower adjustment seat (9) or the lower adjustment seat (9) and the upper mounting seat (8), and a limiting member (25) is provided on the fixed shaft (24) near the movable knife (10) in the avoidance groove, and a reset member (26) is provided between the limiting member (25) and the side wall of the avoidance groove away from the movable knife (10), and an adjusting member is screwed on the end of the fixed shaft (24) away from the movable knife (10), and the adjusting member drives the fixed shaft (24) to move along its axis to drive the movable knife (10) to adjust the distance between it and the fixed knife (11).

4. A sewing machine according to claim 3, characterized in that: The movable knife (10) is mounted on the movable knife bracket (28), a screw portion is provided at one end of the fixed shaft (24), a step surface is formed between the screw portion and the fixed shaft (24), a through hole is provided on the movable knife bracket (28), the screw portion passes through the through hole and is screwed with a locking nut to achieve a fixed connection between the fixed shaft (24) and the movable knife bracket (28).

5. A sewing machine according to claim 4, characterized in that: The movable knife support (28) is further provided with a second waist-shaped hole (33), and an axial screw passes through the second waist-shaped hole (33) and is screwed to the lower adjustment seat (9), and the axis of the axial screw is arranged parallel to the fixed shaft (24).

6. A sewing machine according to claim 1 or 2, characterized in that: The utility model further comprises a line loosening mechanism, wherein a line loosening hole (35) is provided at a portion between the two ends of the driving lever (21), and a line loosening crank (36) of the line loosening mechanism is provided with a line loosening driving pin (37) which is inserted into the line loosening hole (35).

7. A sewing machine according to claim 1 or 2, characterized in that: The invention also includes a rear tugboat mechanism, wherein the other end of the driving lever (21) is connected to one end of a rear tugboat lifting and pressing link (38), the other end of the rear tugboat lifting and pressing link (38) is connected to a lifting and pressing link (41) via a long connecting rod (39) and a rear tugboat crank (40), and the lifting and pressing link (41) is connected to a pressing rod (43) of the rear tugboat mechanism via a stopper (42).

8. A sewing machine according to claim 1 or 2, characterized in that: The lifting member (5) is slidably connected to the slider (12), and the slider (12) is fixed on the mounting seat (3).

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