Sewing machine

Abstract

The invention belongs to the technical field of sewing equipment, and particularly relates to a sewing machine. The thread trimming driving mechanism comprises a thread trimming cam and a lifting piece, a thread trimming driving block is arranged at the upper end of the lifting piece, a thread trimming rolling piece abutting against the cam face of the thread trimming cam is installed on the thread trimming driving block, a movable tool apron is arranged at the lower end of the lifting piece and comprises an upper installation base and a lower adjusting base, and the upper installation base is fixedly connected with the lower end of the lifting piece. The lower adjusting seat is connected with the movable cutter through a linear adjusting mechanism, the linear adjusting mechanism drives the movable cutter to move longitudinally so as to adjust the distance between the movable cutter and the fixed cutter, the lower adjusting seat is connected with the upper mounting seat through a rotary adjusting mechanism, and the rotary adjusting mechanism drives the lower adjusting seat to rotate so as to adjust the inclination angles of the movable cutter and the fixed cutter; the distance and the inclination angle between the movable cutter and the fixed cutter are achieved through linear adjustment and rotary adjustment, the device adapts to different wire thicknesses or abrasion states, and the phenomenon that wires are clamped or are not cut off is prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewing equipment, and particularly relates to a sewing machine. Background Art

[0002] A sewing machine is a machine that uses one or more sewing threads to form one or more stitches on the sewing material, so as to interweave or sew together one or more layers of sewing materials. Currently, most sewing machines are provided with an automatic presser foot lifting device. By controlling the lifting and lowering of the presser foot, the sewing thread is threaded through the sewing material to achieve sewing.

[0003] The sewing machine includes a presser foot lifting mechanism and a thread cutting mechanism. There are also more and more studies on the structure of driving the presser foot lifting and thread cutting by the same drive source. The thread cutting mechanism of the sewing machine usually includes a moving knife and a fixed knife. The moving knife is driven by a drive source to cooperate with the fixed knife to complete the thread cutting action. During the use of the sewing machine, the moving knife and the fixed knife may cause the thread cutting effect to decline due to wear or assembly errors. The moving knife of the traditional thread cutting mechanism is usually fixedly installed and difficult to be finely adjusted, resulting in problems such as incomplete thread cutting or thread jamming, affecting the sewing quality. Summary of the Invention

[0004] The purpose of the present invention is to provide a sewing machine that can adjust the position of the moving knife and improve the thread cutting performance.

[0005] The present invention is realized as follows:

[0006] A sewing machine includes a drive source, a thread cutting mechanism, a thread cutting drive mechanism, a presser foot lifting mechanism, and a presser foot drive mechanism. The drive source has a first rotating shaft and a second rotating shaft. The thread cutting drive mechanism includes a thread cutting cam fixedly arranged on the first rotating shaft, and a lifting member slidably connected to the machine shell. A thread cutting drive block is arranged at the upper end of the lifting member, and a thread cutting rolling member in contact with the cam surface of the thread cutting cam is installed on the thread cutting drive block. A moving knife seat is arranged at the lower end of the lifting member. The moving knife seat includes an upper mounting seat and a lower adjusting seat. The upper mounting seat is fixedly connected to the lower end of the lifting member. The lower adjusting seat is connected to the moving knife through a linear adjusting mechanism. The linear adjusting mechanism drives the moving knife to move longitudinally to adjust the distance between the moving knife and the fixed knife. The lower adjusting seat is connected to the upper mounting seat through a rotational adjusting mechanism. The rotational adjusting mechanism drives the lower adjusting seat to rotate to adjust the inclination angles of the moving knife and the fixed knife.

[0007] In the above-mentioned sewing machine, the presser foot drive mechanism includes a presser foot cam fixedly arranged on the second rotating shaft, and a presser foot crank with one end rotatably arranged on the machine shell or the mounting seat. The other end of the presser foot crank is in contact with the cam surface of the presser foot cam through a presser foot rolling member. A presser foot crank connecting plate is rotatably connected to a position between the two ends of the presser foot crank. The presser foot crank connecting plate is also rotatably connected to one end of a presser foot lever. The other end of the presser foot lever is fixedly connected to the drive lever of the presser foot drive mechanism.

[0008] In one of the above sewing machines, the linear adjustment mechanism includes a fixed shaft. One end of the fixed shaft is fixedly connected to the moving knife, and the other end is movably connected to the lower adjustment seat. An avoidance groove is provided on the lower adjustment seat or between the lower adjustment seat and the upper mounting seat. A limiting member is provided on the fixed shaft near the moving knife within the avoidance groove. A reset member is provided between the limiting member and the side wall of the avoidance groove away from the moving knife end. An adjusting member is screwed to the end of the fixed shaft away from the moving knife. The adjusting member drives the fixed shaft to move along its axis to drive the moving knife to adjust the distance between the moving knife and the fixed knife.

[0009] In one of the above sewing machines, the moving knife is mounted on a moving knife bracket. One end of the fixed shaft is provided with a screw rod portion, and a stepped surface is formed between the screw rod portion and the fixed shaft. A through hole is provided on the moving knife bracket. The screw rod portion passes through the through hole and is screwed with a locking nut to achieve the fixed connection between the fixed shaft and the moving knife bracket.

[0010] In one of the above sewing machines, a second kidney-shaped hole is further provided on the moving knife bracket. An axially-positioned screw passes through the second kidney-shaped hole and is screwed to the lower adjustment seat. The axis of the axially-positioned screw is parallel to the axis of the fixed shaft.

[0011] In one of the above sewing machines, the rotational adjustment mechanism includes a circular hole and a first kidney-shaped hole which are spaced on the lower adjustment seat and arranged parallel to the axis direction of the fixed shaft. The lower adjustment seat is fixedly connected to the upper mounting seat through a first screw passing through the circular hole and is fixedly connected to the upper mounting seat through a second screw passing through the first kidney-shaped hole. By adjusting the position of the second screw within the first kidney-shaped hole, the lower adjustment seat can be driven to rotate around the axis of the first screw, driving the moving knife bracket and the moving knife to rotate around the axis of the first screw to adjust the inclination angle between the moving knife and the fixed knife.

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

[0013] In one of the above sewing machines, a thread-loosening mechanism is further included. A thread-loosening hole is provided in the part between the two ends of the driving lever. A thread-loosening driving pin is provided on the thread-loosening crank of the thread-loosening mechanism and is inserted into the thread-loosening hole.

[0014] In one of the above sewing machines, a rear drag wheel mechanism is further included. The other end of the driving lever is also connected to one end of a rear drag wheel lifting and pressing link. The other end of the rear drag wheel lifting and pressing link is connected to a lifting and pressing link through a long link and a rear drag wheel crank. The lifting and pressing link is connected to a pressure lever of the rear drag wheel mechanism through a stop block.

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

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

[0017] Through linear adjustment and rotational adjustment, the present invention realizes precise adjustment of the distance and inclination angle between the moving knife and the fixed knife, can flexibly adjust the biting gap and contact angle between the moving knife and the fixed knife, ensure the optimal shearing force, adapt to different wire thicknesses or wear states, extend the tool life, and prevent wire jamming or incomplete cutting. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0019] Figure 2 is another three-dimensional schematic diagram of the present invention;

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

[0021] Figure 4 is another schematic diagram of the structure of a driving source of the present invention for driving the presser foot lifting, thread cutting, thread loosening, and rear drag wheel lifting;

[0022] Figure 5 is the schematic diagram of the thread cutting driving mechanism of the present invention;

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

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

[0025] Figure 8 is the schematic diagram of the presser foot driving mechanism of the present invention;

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

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

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

[0029] Figure 12 is another schematic diagram of the moving knife being mounted on the moving knife seat through the moving knife bracket of the present invention;

[0030] Figure 13 isFigure 12 Top view;

[0031] Figure 14 is Figure 13 A - A sectional view of;

[0032] Figure 15 Schematic diagram of the moving knife support of the present invention;

[0033] Figure 16 Schematic diagram of the lower adjusting seat of the present invention.

[0034] In the figure: 1, driving source; 2, housing; 3, mounting seat; 4, thread - cutting cam; 5, lifting member; 6, thread - cutting driving block; 7, moving knife seat; 8, upper mounting seat; 9, lower adjusting seat; 10, moving knife; 11, fixed knife; 12, slider; 13, linear guide rail mounting seat; 14, thread - cutting idle - stroke section; 15, thread - cutting driving section; 16, presser - foot lifting cam; 17, presser - foot lifting crank; 18, presser - foot rolling member; 19, presser - foot lifting crank connecting plate; 20, presser - foot lever; 21, driving lever; 22, presser - foot idle - stroke section; 23, presser - foot driving section; 24, fixed shaft; 25, limiting member; 26, resetting member; 27, adjusting member; 28, moving knife support; 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, thread - loosening hole; 36, thread - loosening crank; 37, thread - loosening driving pin; 38, rear drag wheel presser - foot connecting rod; 39, long connecting rod; 40, rear drag wheel crank; 41, presser - foot connecting rod; 42, stop block; 43, pressure bar. Detailed implementation mode

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

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

[0037] Specifically, the driving source 1 has a first rotating shaft and a second rotating shaft. In this embodiment, the driving source 1 adopts a double - headed motor, and the first rotating shaft and the second rotating shaft extend from both ends of the motor. In order to reasonably allocate the space outside the housing 2 and ensure the reasonable layout of each mechanism, the driving source 1 of the present invention is installed on the mounting seat 3, and the mounting seat 3 is fixedly arranged on the housing 2. The mounting seat of this embodiment includes a vertical plate and a horizontal plate. The horizontal plate is fixedly connected to the housing 2, and the driving source 1 is installed on the vertical plate through a driving - source support. There is a gap between the vertical plate and the corresponding outer side wall of the housing 2.

[0038] Furthermore, the wire cutting drive mechanism includes a wire cutting cam 4 that rotates with the first rotating shaft, and a lifting member 5 slidably arranged on the machine housing 2. A wire cutting drive block 6 is provided at the upper end of the lifting member 5, and a wire cutting rolling member that abuts against the cam surface of the wire cutting cam 4 is installed on the wire cutting drive block 6. The wire cutting rolling member can be a bearing or a roller. A moving knife seat 7 is provided at the lower end of the lifting member 5. The moving knife seat 7 includes an upper mounting seat 8 and a lower adjusting seat 9. The upper mounting seat 8 is fixedly connected to the lower end of the lifting member 5. The lower adjusting seat 9 is connected to the moving knife 10 through a linear adjusting mechanism. The linear adjusting mechanism drives the moving knife 10 to move longitudinally to adjust the distance between the moving knife 10 and the fixed knife 11. The lower adjusting seat 9 is connected to the upper mounting seat 8 through a rotational adjusting mechanism. The rotational adjusting mechanism drives the lower adjusting seat 9 to rotate to adjust the inclination angles of the moving knife 10 and the fixed knife 11.

[0039] The present invention realizes precise adjustment of the distance and inclination angles between the moving knife 10 and the fixed knife 11 through linear adjustment and rotational adjustment, can flexibly adjust the biting gap and contact angle between the moving knife 10 and the fixed knife 11, ensures the optimal shearing force, adapts to different wire thicknesses or wear states, prolongs the tool life, and prevents wire jamming or incomplete cutting.

[0040] In this embodiment, the lifting member 5 is a lifting guide rail, and a slider 12 is arranged on the lifting guide rail. The slider 12 is fixedly arranged on the machine housing 2 or the mounting seat 3 through a linear guide rail mounting seat 13. The lifting member 5 moves up and down along the slider 12 to drive the moving knife 10 to move up and down and cooperate with the fixed knife 11. In addition, the structures of the lifting guide rail and the slider 12 can also be equivalently replaced by the structures of a guide sleeve and a guide rod. With the rigid guidance of the lifting member 5 in the present invention, the movement track of the moving knife 10 is ensured to be stable.

[0041] It should be noted that the wire cutting cam 4 of the present invention includes a wheel body, and a spiral groove is provided on one side surface of the wheel body. The spiral groove includes a wire cutting idle stroke section 14 and a wire cutting drive section 15, and the adjacent sections of the wire cutting idle stroke section 14 and the wire cutting drive section 15 are smoothly transitioned. The distance from the wire cutting drive section 15 to the center of the wire cutting cam 4 gradually increases from one end connected to the wire cutting idle stroke section 14. The wire cutting rolling member is arranged in the spiral groove and rolls along the spiral groove.

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

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

[0044] When lifting the presser foot, the presser foot rolling member 18 rolls on the presser foot driving section 23, while the thread cutting rolling member rolls within the thread cutting idle stroke section 14. Conversely, when cutting the thread, the thread cutting rolling member rolls within the thread cutting driving section 15, while the presser foot rolling member rolls within the presser foot idle stroke section 22, and the two do not interfere with each other.

[0045] Furthermore, as one of the implementation manners, the linear adjustment mechanism includes a fixed shaft 24. One end of the fixed shaft 24 is fixedly connected to the moving knife 10, and the other end is movably connected to the lower adjustment seat 9. An avoidance groove is provided on the lower adjustment seat 9 or between the lower adjustment seat 9 and the upper mounting seat 8. A limiting member 25 is provided on the fixed shaft 24 close to the moving knife 10 within the avoidance groove, and a reset member 26 is provided between the limiting member 25 and the side wall of the avoidance groove far from the moving knife 10. An adjusting member 27 is screwed to the end of the fixed shaft 24 far from the moving knife 10. The adjusting member 27 drives the fixed shaft 24 to move along its axis to drive the moving knife 10 to adjust the distance between the moving knife 10 and the fixed knife 11. Among them, the limiting member 25 adopts a retaining ring or a circlip, the reset member 26 adopts a spring or a spring piece, etc., and the adjusting member 27 adopts an adjusting knob or an adjusting nut, etc.

[0046] As another implementation manner, the linear adjustment mechanism can adopt a gear-rack adjustment structure. For example, a rack portion is machined on the side of the fixed shaft, and the rack portion extends outside the lower adjustment seat. A gear meshing with the rack is rotatably provided on the lower adjustment seat, and rotating the gear drives the fixed shaft to move.

[0047] It should be noted that the moving knife 10 of the present invention is installed on the moving knife bracket 28. One end of the fixed shaft 24 is provided with a screw rod portion, and a step surface is formed between the screw rod portion and the fixed shaft 24. A through hole is provided on the moving knife bracket 28. The screw rod portion passes through the through hole and is screwed with a locking nut to realize the fixed connection between the fixed shaft 24 and the moving knife bracket 28, and the moving knife bracket 28 is limited between the step surface and the locking nut.

[0048] In addition, as one of the implementation manners, the rotation adjustment mechanism includes a circular hole 29 and a first waist-shaped hole 30 which are arranged at intervals on the lower adjustment base 9 and are arranged parallel to the axis direction of the fixed shaft 24. The lower adjustment base 9 is fixedly connected to the upper mounting base 8 through a first screw passing through the circular hole 29 and is fixedly connected to the upper mounting base 8 through 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 base 9 can be driven to rotate around the axis of the first screw, driving the moving knife support 28 and the moving knife 10 to rotate around the axis of the first screw to adjust the inclination angle between the moving knife 10 and the fixed knife 11. By adjusting the inclination angle, the problem of blade misalignment caused by assembly errors can be solved, so that the cutting edges of the moving knife 10 and the fixed knife 11 are completely fitted, improving the smoothness of wire cutting.

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

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

[0051] It should be noted that the present invention also provides a second waist-shaped hole 33 on the moving knife support 28, and an axial position screw passes through the second waist-shaped hole 33 and is screwed to the lower adjustment base 9. The axis of the axial position screw is arranged parallel to the fixed shaft 24. With such a setting, the second waist-shaped hole 33 and the axial position screw allow a small displacement of the moving knife support 28 when adjusting the inclination angle, avoiding structural interference. At the same time, it can also prevent the moving knife support 28 from rotating around the fixed shaft 24.

[0052] In addition, the present invention also provides third waist-shaped holes 34 on both sides of the second waist-shaped hole 33 on the moving knife support 28. The moving knife 10 is fixedly connected to the moving knife support 28 through screws passing through the third waist-shaped holes 34. With such a setting, the adjustable range of the position of the moving knife 10 is further expanded, adapting to different wire materials or cutting requirements and enhancing the structural versatility.

[0053] The present invention also performs a wire loosening action while lifting the presser foot. Specifically, the structure of the present invention further includes a wire loosening mechanism. A wire loosening hole 35 is arranged on the part between the two ends of the driving lever 21, and a wire loosening driving pin 37 penetrating through the wire loosening hole 35 is arranged on the wire loosening crank 36 of the wire loosening mechanism.

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

[0055] The above embodiments are only one of the preferred embodiments of the present invention, and do not limit the scope of implementation of the present invention. Therefore, all equivalent changes made according to the shape, structure, and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A sewing machine, comprising a drive source (1), a thread cutting mechanism, a thread cutting drive mechanism, a presser foot lifting mechanism, and a presser foot lifting drive mechanism, wherein the drive source (1) has a first rotating shaft and a second rotating shaft, and is characterized in that: The wire cutting driving mechanism includes a wire cutting cam (4) fixedly arranged on the first rotating shaft and a lifting member (5) slidably connected to the machine housing (2). A wire cutting driving block (6) is arranged at the upper end of the lifting member (5). A wire cutting rolling member abutted against the cam surface of the wire cutting cam (4) is installed on the wire cutting driving block (6). A moving knife seat (7) is arranged at the lower end of the lifting member (5). The moving knife seat (7) includes an upper mounting seat (8) and a lower adjusting seat (9). The upper mounting seat (8) is fixedly connected to the lower end of the lifting member (5). The lower adjusting seat (9) is connected to the moving knife (10) through a linear adjusting mechanism. The linear adjusting mechanism drives the moving knife (10) to move longitudinally to adjust the distance between the moving knife (10) and the fixed knife (11). The lower adjusting seat (9) is connected to the upper mounting seat (8) through a rotational adjusting mechanism. The rotational adjusting mechanism drives the lower adjusting seat (9) to rotate to adjust the inclination angles of the moving knife (10) and the fixed knife (11).

2. The sewing machine according to claim 1, characterized in that: The presser foot lifting driving mechanism includes a presser foot lifting cam (16) fixedly arranged on the second rotating shaft and a presser foot lifting crank (17) with one end rotatably arranged on the machine housing (2) or the mounting seat (3). The other end of the presser foot lifting crank (17) abuts against the cam surface of the presser foot lifting cam (16) through a presser foot lifting rolling member (18). A presser foot lifting crank connecting plate (19) is rotatably connected to a position 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). 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 adjusting mechanism includes a fixed shaft (24). One end of the fixed shaft (24) is fixedly connected to the moving knife (10), and the other end is movably connected to the lower adjusting seat (9). Avoidance grooves are arranged on the lower adjusting seat (9) or between the lower adjusting seat (9) and the upper mounting seat (8). A limiting member (25) is arranged on the fixed shaft (24) close to the moving knife (10) in the avoidance groove. A reset member (26) is arranged between the limiting member (25) and the side wall of the avoidance groove away from one end of the moving knife (10). An adjusting member is screwed to the end of the fixed shaft (24) away from the moving knife (10). The adjusting member drives the fixed shaft (24) to move along its axis to drive the moving knife (10) to adjust the distance between the moving knife (10) and the fixed knife (11).

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

5. A sewing machine according to claim 4, characterized in that: A second kidney-shaped hole (33) is also arranged on the moving knife bracket (28). An axially-positioned screw passes through the second kidney-shaped hole (33) and is screwed to the lower adjusting seat (9). The axis of the axially-positioned screw is arranged parallel to the fixed shaft (24).

6. A sewing machine according to claim 1 or 2, characterized in that: The rotation adjustment mechanism includes a circular hole (29) and a first kidney-shaped hole (30) which are arranged at intervals on the lower adjustment base (9) and are parallel to the axis direction of the fixed shaft (24). The lower adjustment base (9) is fixedly connected to the upper mounting base (8) through the first screw passing through the circular hole (29), and is fixedly connected to the upper mounting base (8) through the second screw passing through the first kidney-shaped hole (30). By adjusting the position of the second screw in the first kidney-shaped hole (30), the lower adjustment base (9) can be driven to rotate around the axis of the first screw, driving the moving knife support (28) and the moving knife (10) to rotate around the axis of the first screw to adjust the inclination angle between the moving knife (10) and the fixed knife (11).

7. A sewing machine according to claim 6, characterized in that: An adjustment screw (31) is arranged on one side wall of the upper mounting base (8), and a limit groove (32) is arranged on the lower adjustment base (9). The adjustment screw (31) has a head that can extend into the limit groove (32) and abut against the inner side wall of the limit groove (32), and a screw rod that is screwed to the upper mounting base (8). The inner side wall of the limit groove (32) is parallel to the axis of the fixed shaft (24). By rotating the adjustment screw (31) and loosening the second screw, the lower adjustment base (9) can be driven to rotate around the axis of the first screw.

8. The sewing machine according to claim 2, characterized in that: It further includes a wire loosening mechanism. A wire loosening hole (35) is arranged on the part between the two ends of the driving lever (21). A wire loosening driving pin (37) which is arranged on the wire loosening crank (36) of the wire loosening mechanism is inserted into the wire loosening hole (35).

9. A sewing machine according to claim 2, characterized in that: It further includes a rear idler wheel mechanism. The other end of the driving lever (21) is also connected to one end of a rear idler wheel lifting and pressing connecting rod (38). The other end of the rear idler wheel lifting and pressing connecting rod (38) is connected to a lifting and pressing connecting rod (41) through a long connecting rod (39) and a rear idler wheel crank (40). The lifting and pressing connecting rod (41) is connected to a pressing rod (43) of the rear idler wheel mechanism through a stop block (42).

10. 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 fixedly arranged on the mounting base (3).

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