CN217997542U

CN217997542U - Flat buttonhole machine

Info

Publication number: CN217997542U
Application number: CN202221468045.8U
Authority: CN
Inventors: 阮孟国
Original assignee: Meisuo Sewing Machine Co ltd
Current assignee: Meisuo Sewing Machine Co ltd
Priority date: 2022-06-09
Filing date: 2022-06-09
Publication date: 2022-12-09
Anticipated expiration: 2032-06-09

Abstract

The utility model relates to the technical field of sewing machines, in particular to a flat buttonhole sewing machine. The thread trimming and presser foot lifting transmission mechanism of the buttonholing machine is simple in structure and separated in transmission of the thread trimming and thread loosening mechanism, the thread loosening mechanism and the cutter device. A motor shaft of a driving motor of a straight buttonhole machine is provided with a crank rocker mechanism. The crank rocker mechanism enables the rocker to do reciprocating motion, when the rocker is lifted, the thread loosening mechanism is driven to work, power is transmitted to the thread clamping mechanism and the thread loosening mechanism through the thread loosening lever, when the rocker is lowered, the thread shearing mechanism and the presser foot lifting mechanism are driven to work, the thread loosening mechanism, the thread shearing mechanism and the presser foot lifting mechanism are separated in action, and the operation stability of the buttonholing machine is improved. Be provided with solitary cutter driving motor, can independently carry out work, overall structure is simple, need not just can make the cutter carry out accurate the reseing of other subassemblies, has simplified mechanical structure, can reduce the fault rate again when being convenient for install and maintain.

Description

Flat buttonhole machine

Technical Field

The utility model relates to the technical field of sewing machines, in particular to a flat-head buttonhole sewing machine.

Background

CN201621155972.9 discloses a straight buttonhole sewing machine, is provided with the electro-magnet at the rear end of frame, drives trimming mechanism and lifts presser foot mechanism through the electro-magnet connecting rod, and the electro-magnet connecting rod is connected with the middle part of starting the connecting rod, and the upper end of starting the connecting rod passes through axle position screw setting and can swing around the axle position screw on the casing, and the middle part of starting the connecting rod still is connected with connecting rod one, and connecting rod one is connected with connecting rod three through connecting rod two, and the middle part of connecting rod three is provided with the facial line and cuts off scissors protection connecting rod.

The technical scheme has the following defects:

the transmission structure is comparatively complicated, and the transmission between electro-magnet connecting rod, start-up connecting rod and the connecting rod is unstable, and power transmits simultaneously to last trimming mechanism, lower trimming mechanism, lift presser foot mechanism and thread slackening mechanism for the subassembly is concentrated relatively, and the structure is complicated, causes inconvenience when installation and maintenance.

SUMMERY OF THE UTILITY MODEL

The utility model aims at providing a buttonhole maker with simplified structure and separated thread cutting and thread loosening mechanism.

The utility model aims at realizing the following steps:

a buttonhole sewing machine includes a frame;

the first driving motor is mounted on the mounting frame of the rack, and a driving gear is arranged on a motor shaft of the first driving motor;

the first rack is arranged on the longitudinal guide mechanism and meshed with the driving gear;

and a linkage connecting rod is arranged on the first rack, a strip-shaped limiting hole is formed in the linkage connecting rod, a cylindrical pin is arranged at the front end of the main swing arm, and the cylindrical pin is arranged in the limiting hole. When the driving motor is started, the driving gear drives the rack I to move up and down along the longitudinal guide mechanism, the limit hole realizes stroke limit on the cylindrical pin, and the upper surface of the limit hole drives the main swing arm to swing by pushing the cylindrical pin.

An upper surface of the rack is provided with a pushing portion, the pushing portion can push the L-shaped iron piece, the L-shaped iron piece is connected with the thread releasing mechanism, and the pushing portion pushes the bottom surface of the L-shaped iron piece to enable the L-shaped iron piece to be lifted, so that power is transmitted to the thread releasing mechanism.

Preferably, a fixing hole is formed in an inclined surface of the protruding portion of the upper surface of the first rack, and a bolt is arranged in the fixing hole, so that the pushing portion connected to the first rack can be reinforced.

Preferably, a spring connecting hole is formed in one side, close to the first driving motor, of the main swing arm, a spring is arranged in the spring connecting hole, so that the main swing arm can be connected with the upper end of the rack in the upward direction, and the main swing arm tends to be lifted upwards through elasticity of the spring. So that the cylindrical pin arranged on the main swing arm can abut against the upper surface of the limiting hole.

Preferably, a buttonhole maker, including above, also includes the thread releasing lever;

the thread releasing lever is fixed on the mounting frame through a fixing bolt, the thread releasing lever is connected with a reset lever, and the reset lever is fixed on the mounting frame through the fixing bolt;

the thread releasing lever and the fulcrum of the reset lever are the fixing bolts, the reset lever can be connected with a reset spring, and the reset spring can enable the thread releasing lever to reset.

Preferably, the L-shaped iron piece is bolted on the thread releasing lever, and when the L-shaped iron piece is pushed and lifted by the rack, the thread releasing lever can be rotated to drive the thread releasing connecting rod to transmit power to the thread releasing mechanism.

Preferably, a second driving motor is arranged on the rack;

a motor shaft of the driving motor II is provided with a crank, and the other end of the crank is connected with the connecting rod I; the first connecting rod is provided with two end parts, one end of the first connecting rod is hinged to the crank, and the other end of the first connecting rod is hinged to the second connecting rod; the second connecting rod is in an inverted concave shape and comprises two vertical edges and a transverse edge, and the first connecting rod is hinged to the two vertical edges or the two ends of the transverse edge.

Preferably, when a motor shaft of the second driving motor rotates for a circle, the second connecting rod can be driven to complete one-time up-and-down reciprocating motion; the other end of the second connecting rod is connected with the cutter mechanism, and when the second connecting rod reciprocates up and down, the cutter can be driven to perform material cutting.

Preferably, the rack is provided with a guide rail, the guide rail is provided with a sliding block, and the guide rail can enable the sliding block to move longitudinally without transverse displacement;

an eccentric wheel is arranged on a motor shaft of the driving motor II, the eccentric wheel is connected with a connecting rod I, the other end of the connecting rod I is hinged to a sliding block, the eccentric wheel is connected with the sliding block through the connecting rod I, and the driving motor II can drive the sliding block to do longitudinal reciprocating motion, so that the cutting knife mechanism drives the cutting knife to perform cutting action.

Preferably, the sliding block extends towards the second driving motor to form a second rack, and a second driving motor gear is arranged on a motor shaft of the second driving motor;

the second driving motor can drive the sliding block to do longitudinal reciprocating motion through the engagement of the second driving motor gear and the second rack, so that the cutter mechanism drives the cutter to perform a material cutting action.

Compared with the prior art, the utility model outstanding and profitable technological effect is:

1. the L-shaped iron piece is pushed by the pushing portion arranged on the rack, the presser foot lifting lever is driven to rotate, and power is transmitted to the wire clamping mechanism and the presser foot lifting mechanism through the presser foot lifting lever, so that the wire clamping mechanism, the presser foot lifting mechanism and the wire shearing mechanism are separated, and the whole structure is simplified.

2. The wire clamping mechanism, the presser foot lifting mechanism and the wire shearing mechanism are separated, so that the number of parts connected with the main swing arm is reduced, the power required to be transmitted by the main swing arm is reduced, and the structural stability is improved.

3. The pushing part of the rack pushes the L-shaped iron piece, so that the action of the presser foot lifting mechanism can be controlled, the continuity of the presser foot lifting action and the thread trimming action is kept when the presser foot lifting mechanism is separated from the thread trimming mechanism, the mutual interference between the presser foot lifting action and the thread trimming action is reduced, and the running stability of the sewing machine is improved.

4. The cutter can be accurately reset without other components, the mechanical structure is simplified, and the failure rate can be reduced while the installation and the maintenance are convenient.

Drawings

Fig. 1 is a rear view of the present invention.

Fig. 2 is a schematic structural view of the thread cutting and presser foot lifting transmission mechanism of the present invention.

Fig. 3 is an enlarged view of a in fig. 2.

Fig. 4 is a left side view of the structure of the transmission mechanism for trimming and lifting the presser foot according to the present invention.

Fig. 5 is a schematic view of another angle of the transmission mechanism for trimming and lifting the presser foot according to the present invention.

Fig. 6 is a schematic structural diagram of a cutter device according to a first embodiment of the present invention.

Fig. 7 is a schematic structural view of a cutter device according to a second embodiment of the present invention.

Fig. 8 is a schematic structural view of a cutting device in a third embodiment of the present invention.

Reference numerals are as follows: 1-a frame; 11-a mounting frame;

2, driving a first motor; 21-a drive gear; 22-longitudinal guide means; 23-rack one; 24-a linkage link; 25-limiting holes; 26-a pushing part; 27-a fixing hole;

3-main swing arm; 31-cylindrical pins; 32-spring attachment holes; 33-trimming connecting rod;

4-a thread releasing mechanism; 41-L-shaped iron pieces; 42-a thread-releasing lever; 43-loose wire linkage; 44-a reset link; 45-fixing the bolt;

5-a thread trimming mechanism; 6, a wire clamping mechanism;

7-driving a motor II; 71-crank; 72-connecting rod one; 73-link two; 74-a cutter mechanism; 75-a cutter; 76-eccentric wheel; 77-a slider; 78-a guide rail; 79-driving motor two gears; 80-rack two.

Detailed Description

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

The first embodiment is as follows:

as shown in fig. 1-6, a buttonholing machine, a second driving motor 7 is arranged on a frame 1;

a motor shaft of the second driving motor 7 is provided with a crank 71, and the other end of the crank 71 is connected with a first connecting rod 72; the first connecting rod 72 is provided with two end parts, one end of the first connecting rod 72 is hinged on the crank 71, and the other end of the first connecting rod 72 is hinged on the second connecting rod 73; the second connecting rod 73 is in an inverted concave shape and comprises two vertical edges and a transverse edge, the first connecting rod 72 is hinged to the two vertical edges or the two ends of the transverse edge, and the other end of the second connecting rod 73 is connected with the cutter mechanism 74.

When the motor shaft of the second driving motor 7 rotates for one circle, the second connecting rod 73 can be driven to complete one up-and-down reciprocating motion. Because the other end of the second connecting rod 73 is connected with the cutter mechanism 74, and because the cutter mechanism 74 is only connected with the second connecting rod 73, when the second connecting rod 73 is displaced, the cutter mechanism 74 is driven to move together. When the second connecting rod 73 reciprocates up and down, the cutter mechanism 74 also reciprocates up and down and drives the cutter 75 to perform a material cutting operation.

The driving motor I2 is arranged on the mounting frame 11 of the rack 1, and a driving gear 21 is arranged on a motor shaft of the driving motor I2;

the first rack 23 is arranged on the longitudinal guide mechanism 22, and the first rack 23 is meshed with the driving gear 21;

a linkage connecting rod 24 is arranged on the first rack 23, a strip-shaped limiting hole 25 is formed in the linkage connecting rod 24, a cylindrical pin 31 is arranged at the front end of the main swing arm 3, and the cylindrical pin 31 is placed in the limiting hole 25. When the first driving motor 2 is started, the first driving gear 21 drives the first rack 23 to move up and down along the longitudinal guide mechanism 22, the limit hole 25 limits the stroke of the cylindrical pin 31, and the upper surface of the limit hole 25 drives the main swing arm 3 to swing by pushing the cylindrical pin 31.

The main swing arm 3 is provided with a thread cutting connecting rod 33, one end of the main swing arm 3 is fixed on the sewing machine frame 1, and when the upper surface of the linkage connecting rod 24 pushes the cylindrical pin 31 to drive the main swing arm 3 to swing, the power is transmitted to the thread cutting mechanism 5 through the thread cutting connecting rod 33.

The pushing portion 26 is arranged on the upper surface of the first rack 23, the L-shaped iron piece 41 can be pushed by the pushing portion 26, the L-shaped iron piece 41 is connected with the thread releasing mechanism 4, the bottom surface of the L-shaped iron piece 41 is pushed by the pushing portion 26, the L-shaped iron piece 41 is lifted, and therefore power is transmitted to the thread releasing mechanism 4.

In the standing state, the first rack 23 is positioned at the upper part of the longitudinal guide mechanism 22, and the pushing part 26 keeps the state of jacking the L-shaped iron piece 41, so that the thread releasing mechanism 4 performs the thread releasing action.

When the first driving motor 2 is started, the first driving gear 21 drives the first rack 23 to move downwards, the pushing portion 26 gradually separates from the L-shaped iron piece 41, transmission is separated, and therefore the thread releasing mechanism 4 loses power.

As shown in fig. 3 and 4, a fixing hole 27 is formed at the inclined surface of the convex part of the upper surface of the first rack 23, and a bolt is arranged in the fixing hole 27; the bolt is used for reinforcing the pushing part 26 connected to the rack gear I23, or the cap part of the bolt forms the pushing part 26.

After the pushing part 26 is connected with the first rack 23, the lower surface of the L-shaped iron 41 needs to be pushed by the part of the pushing part 26 exposed out of the first rack 23 to transmit power. In order to avoid the situation that the pushing part 26 is broken or the fastening effect on the pushing part 26 is lost due to the damage of the protruding part of the rack-one 23 in the process of pushing the L-shaped iron piece 41, a fixing hole 27 is formed on the upper surface of the rack-one 23. By reinforcing the pushing portion 26 with bolts, the shearing force is balanced, and the occurrence of damage to the rack one 23 or breakage of the pushing portion 26 can be reduced.

As shown in fig. 3, a spring connection hole 32 is formed in one side of the main swing arm 3 close to the first driving motor 2, the spring is arranged in the spring connection hole 32, so that the main swing arm 3 is connected with the upper end of the rack 1, the main swing arm 3 tends to be lifted upwards due to elasticity of the spring, and a cylindrical pin 31 arranged on the main swing arm 3 can abut against the upper surface of the limiting hole 25.

Through the spring connecting hole 32 arranged on the main swing arm 3, the spring connected to the sewing machine frame 1 can enable one end, close to the first driving motor 2, of the main swing arm 3 to be kept lifted, and the cylindrical pin 31 can be abutted to the upper surface of the limiting hole 25.

As shown in fig. 1-5, a thread releasing lever 42 is also included;

the thread releasing lever 42 is fixed on the mounting frame 11 through a fixing bolt 45, the thread releasing lever 42 is connected with a reset lever 44, and the reset lever 44 is fixed on the mounting frame 11 through the fixing bolt 45;

the fulcrum of the thread releasing lever 42 and the reset lever 44 is a fixing bolt 45, the reset lever 44 can be connected with a reset spring, and the reset spring can reset the thread releasing lever 42.

Because the fulcrum of the thread releasing lever 42 and the reset lever 44 are both positioned at the fixing bolt 45, one end of the reset lever 44 is fixed on the thread releasing lever 42, and the other end faces the direction of the thread releasing mechanism 4. One end of the direction towards the thread releasing mechanism 4 is provided with a return spring, one end of the return spring is connected with the machine frame 1, and the other end of the return spring is connected with the upper end of the return connecting rod 44. When the L-shaped iron 41 pushes the presser foot lifting lever 42 to rotate, the return link 44 is driven to rotate, so that the return spring connected to the return link 44 is elongated. When the first rack 23 is separated from the L-shaped iron member 41, the spring provided on the reset lever 44 can provide an opposite force to reset the thread releasing lever 42 and drive the thread clamping mechanism 5 to rotate.

As shown in fig. 1-5, the L-shaped iron 41 is bolted to the thread releasing lever 42, when the L-shaped iron 41 is pushed and lifted by the first rack 23, the thread releasing lever 42 is rotated, and the thread releasing link 43 is driven to transmit power to the thread releasing mechanism 4.

When the first driving motor 2 is started, the first rack 23 falls down from the upper end of the longitudinal guide mechanism 22, and the linkage connecting rod 24 arranged on the first rack 23 moves downwards along with the falling of the first rack 23. At this time, the upper surface of the limiting hole 25 contacts the cylindrical pin 31 and pushes the cylindrical pin 31 to move downwards, so that the main swing arm 3 is inclined downwards through the cylindrical pin 31. When the main swing arm 3 is inclined downwards, the trimming connecting rod 33 can push the trimming mechanism 5, so that the trimming mechanism 5 executes trimming.

At the moment, as the L-shaped iron piece 41 is separated from the first rack 23, the reset lever 44 drives the thread releasing lever 42 to rotate, so that the thread releasing lever 42 drives the thread clamping mechanism 6 to release, the suture passes through the thread clamping device without resistance, and the suture is ensured to be smoothly cut by the thread cutting knife.

After the thread cutting action is finished, the first driving motor 2 enables the first rack 23 to be lifted, and the pushing portion 26 abuts against the lower surface of the L-shaped iron piece 41 again and pushes the L-shaped iron piece to be lifted. When the pushing part 26 pushes the lower surface of the L-shaped iron 41, since the thread releasing lever 42 is fixed on the mounting frame 11, the L-shaped iron 41 is lifted to rotate the thread releasing lever 42 and pull the thread releasing link 43, so that power is transmitted to the thread releasing mechanism 4, the thread clamping mechanism 6 is rotated, and the thread is clamped by the thread clamp. When the thread trimming mechanism 5 and the thread loosening mechanism 4 are separated, the continuity between the thread trimming action and the thread loosening action is ensured, and the running stability of the buttonholing machine is improved.

As shown in fig. 1 and 6, a second driving motor 7 is arranged on the frame 1;

a motor shaft of the driving motor II 7 is provided with a crank 71, and the other end of the crank 71 is connected with a connecting rod I72; the first connecting rod 72 is provided with two end parts, one end of the first connecting rod 72 is hinged on the crank 71, and the other end of the first connecting rod 72 is hinged on the second connecting rod 73; the second connecting rod 73 is of an inverted concave shape and comprises two vertical edges and a transverse edge, and the first connecting rod 72 is hinged to the two vertical edges or the two ends of the transverse edge.

The crank 71 is eccentrically arranged on the second driving motor 7, and when the second driving motor 7 rotates through the driving crank 71, the first connecting rod 72 is driven to swing, and the second connecting rod 73 is driven to move up and down through the first connecting rod 72. By using the independent driving motor II 7 and driving the connecting rod II 73 to independently drive the cutter mechanism 74 to reciprocate through the connecting rod I72, the material cutting and the returning can be completed, the connection relation with the driving motor I2 and other mechanisms is avoided, the material cutting can be completed independently without the driving motor I2 and the associated mechanisms, and the failure rate is reduced.

As shown in fig. 6, when the motor shaft of the second driving motor 7 rotates for one circle, the second connecting rod 73 can be driven to complete one up-and-down reciprocating motion;

the other end of the second connecting rod 73 is connected with the cutter mechanism 74, and when the second connecting rod 73 reciprocates up and down, the cutter 75 can be driven to perform a material cutting action.

The structure can lead the cutter 7 to accurately reset without additionally using a spring, thereby simplifying the structure and reducing the failure rate.

The cutter shaft of the driving motor II 7 rotates by 0-180 degrees to reach the lowest point, and returns to the initial point by 180-360 degrees to finish the action of the cutter (without stopping); if the control is a reciprocating type action control, for example, the cutter rotates 0-180 degrees to reach the lowest point, the original path returns 180-0 degrees to finish the cutting action, and the action of the cutter stops at 180 degrees.

Driving motor is step motor, its advantage of driving the cutter:

1. the cutting knife does not need to obtain power from a main motor, works independently and is silent (noise is greatly reduced);

2. the main motor is not required to obtain power, and the rotating speed of the main motor is not required to be reduced; therefore, the cutter can be carried out under the condition of keeping the high-speed running of the main motor; the benefit is improved by 8-10%, and the benefit is higher than that of a common buttonholing machine;

3. the cutter is not clamped, the motor shaft of the second driving motor 7 rotates for a circle to complete the cutter, and the cutter can be forcibly withdrawn even if slight resistance exists in the cutter process, so that the problem of clamping is avoided;

4. without obtaining power from the main motor, the number of parts is reduced, thereby decreasing the failure rate and increasing the life (although the electric control is increased, the number of parts of the whole buttonhole maker is reduced)

5. A sensor can be additionally arranged to detect sewing threads; the device can automatically stop after the wire is broken, and the material loss is reduced.

Example two:

the embodiment is different from the first embodiment only in the cutter device part, and the keyhole device part is the same as the first embodiment, and the description is omitted.

As shown in fig. 7, the frame 1 is provided with a guide rail 78, the guide rail 78 is provided with a slide block 77, and the guide rail 78 can allow the slide block 77 to move longitudinally without lateral displacement;

an eccentric wheel 76 is arranged on a motor shaft of the second driving motor 7, the eccentric wheel 76 is connected with a first connecting rod and connecting rod 72, the other end of the first connecting rod 72 is hinged to a sliding block 77, so that the eccentric wheel 76 and the sliding block 77 are connected through the first connecting rod 72, and the second driving motor 7 can drive the sliding block 77 to do longitudinal reciprocating motion, so that the cutting knife mechanism 74 drives the cutting knife 75 to do material cutting motion.

When the second driving motor 7 is started, the first connecting rod 73 rotates along with the eccentric wheel 76, so that the sliding block 77 is pushed to move, and the sliding block 77 is limited by the guide rail 78 and can only move longitudinally but cannot move transversely. So that the connected cutter mechanism 74 can be kept at the same position to drive the cutter 75 to perform the material cutting action.

The second driving motor is arranged independently, the second driving motor can work independently, the cutter 75 can be reset accurately without other assemblies, the mechanical structure is simplified, and the failure rate can be reduced while the installation and maintenance are facilitated.

Example three:

the embodiment is different from the second embodiment only in the cutter device part, and the keyhole device part is the same as the first embodiment, and the description is not repeated.

As shown in fig. 8, the sliding block 77 extends toward the second driving motor 7 to form a second rack 80, and a second driving motor gear 79 is arranged on a motor shaft of the second driving motor 7;

the second driving motor gear 79 is meshed with the second rack 80, so that the second driving motor 7 can drive the sliding block 76 to do longitudinal reciprocating motion, and the cutting mechanism 74 drives the cutting knife 75 to perform a cutting action.

The difference between the present embodiment and the second embodiment is that the sliding block 77 extends towards the second driving motor 7, the extending portion forms a second rack 80, and the eccentric wheel 76 disposed on the second driving motor 7 is eliminated, and a second driving motor gear 79 capable of meshing with the second rack 80 is disposed. Through the meshing of the second driving motor gear 79 and the second rack 80, the power of the second driving motor 7 is transmitted to the sliding block 77 to drive the sliding block 77 to do longitudinal reciprocating motion, so that the cutter mechanism 74 can execute the material cutting operation.

The second driving motor is arranged independently, the cutter 75 can be reset accurately without other components, the mechanical structure is simplified, and the failure rate can be reduced while the installation and maintenance are facilitated.

The specific structure that buttonholing machines have trimming and presser foot lifting is prior art, and this application is not expanded in detail.

The above-mentioned embodiment is only the preferred embodiment of the present invention, and does not limit the protection scope of the present invention according to this, so: all equivalent changes made according to the structure, shape and principle of the utility model should be covered within the protection scope of the utility model.

Claims

1. A straight buttonhole machine comprises a frame (1); it is characterized by also comprising

The first driving motor (2) is mounted on a mounting frame (11) of the rack (1), and a driving gear (21) is arranged on a motor shaft of the first driving motor (2);

the first rack (23), the first rack (23) is arranged on the longitudinal guide mechanism (22), and the first rack (23) is meshed with the driving gear (21); the driving gear (21) drives the rack I (23) to move up and down along the longitudinal guide mechanism (22),

a linkage connecting rod (24) is arranged on the first rack (23), and the linkage connecting rod (24) drives the main swing arm (3); the main swing arm (3) drives the thread trimming mechanism (5) and the presser foot lifting mechanism;

and a second driving motor (7) is further arranged on the rack (1), and the second driving motor (7) drives the cutter mechanism (74) to lift.

2. The flat head buttonhole machine according to claim 1, characterized in that a strip-shaped limiting hole (25) is formed in the linkage connecting rod (24), a cylindrical pin (31) is arranged at the front end of the main swing arm (3), and the cylindrical pin (31) is placed in the limiting hole (25);

the limiting hole (25) limits the stroke of the cylindrical pin (31), and the upper surface of the limiting hole (25) drives the main swing arm (3) to swing by pushing the cylindrical pin (31).

3. The straight buttonhole machine according to claim 1, characterized in that the upper surface of the first rack (23) is provided with a pushing part (26), the pushing part (26) can push an L-shaped iron piece (41), the L-shaped iron piece (41) is connected with the thread releasing mechanism (4), and the pushing part (26) pushes the bottom surface of the L-shaped iron piece (41) to lift the L-shaped iron piece (41), so that power is transmitted to the thread releasing mechanism (4).

4. A buttonhole sewing machine according to claim 1, characterised in that a fixing hole (27) is provided on one side of the upper part of the first rack (23), that a bolt is provided in the fixing hole (27), and that the cap of the bolt forms the pushing part (26).

5. A flat buttonhole machine according to claim 2, characterized in that a spring connecting hole (32) is formed in one side of the main swing arm (3) close to the first driving motor (2), the main swing arm (3) can be connected with the upper end of the frame (1) by arranging a spring in the spring connecting hole (32), the main swing arm (3) is enabled to present a tendency of lifting upwards through the elasticity of the spring, and the cylindrical pin (31) arranged on the main swing arm (3) can abut against the upper surface of the limiting hole (25).

6. A buttonhole sewing machine according to claim 3, characterised in that it further comprises a thread-releasing lever (42);

the thread releasing lever (42) is fixed on the mounting rack (11) through a fixing bolt (45), the thread releasing lever (42) is connected with a reset lever (44), and the reset lever (44) is fixed on the mounting rack (11) through the fixing bolt (45);

the supporting points of the thread releasing lever (42) and the reset lever (44) are the fixing bolts (45), the reset lever (44) can be connected with a reset spring, and the reset spring can reset the thread releasing lever (42).

7. A buttonhole sewing machine according to claim 6, characterized in that the L-shaped iron (41) is bolted to a thread releasing lever (42), when the L-shaped iron (41) is pushed and lifted by the first rack (23), the thread releasing lever (42) can be rotated to drive a thread releasing link (43) to transmit power to the thread releasing mechanism (4).

8. The buttonhole sewing machine according to claim 1, characterised in that the specific transmission structure between the second driving motor (7) and the cutter mechanism (74) is:

a crank (71) is arranged on a motor shaft of the driving motor II (7), and the other end of the crank (71) is connected with the connecting rod I (72); the first connecting rod (72) is provided with two end parts, one end of the first connecting rod (72) is hinged to the crank (71), the other end of the first connecting rod (72) is hinged to the second connecting rod (73), and the other side of the second connecting rod (73) is fixed with a guide rod of the cutter mechanism (74); the lower part of the guide rod is provided with a cutter (75).

9. The straight-head buttonhole machine according to claim 8, characterised in that said second connecting rod (73) is of inverted concave shape comprising two vertical edges and one transverse edge; the first connecting rod (72) is hinged to the vertical edge of the front side, and the guide rod is fixed to the vertical edge of the rear side.

10. The buttonhole sewing machine according to claim 1, characterised in that the specific transmission structure between the second driving motor (7) and the cutter mechanism (74) is:

a guide rail (78) is arranged on the rack (1), a sliding block (77) is mounted on the guide rail (78), and the guide rail (78) can enable the sliding block (77) to move longitudinally;

an eccentric wheel (76) is arranged on a motor shaft of the second driving motor (7), the eccentric wheel (76) is connected with a first connecting rod (72), the other end of the first connecting rod (72) is hinged to a sliding block (77), so that the eccentric wheel (76) and the sliding block (77) are connected through the first connecting rod (72), the second driving motor (7) can drive the sliding block (77) to do longitudinal reciprocating motion, and one side of the sliding block (77) extends outwards and is fixed with a guide rod of the cutting knife mechanism (74);

or the specific transmission structure between the second driving motor (7) and the cutter mechanism (74) is as follows:

the sliding block (77) extends towards the second driving motor (7) to form a second rack (80), and a second driving motor gear (79) is arranged on a motor shaft of the second driving motor (7); the sliding block (77) is arranged on the guide rail (78), and the driving motor II (7) can drive the sliding block (77) to do longitudinal reciprocating motion through the meshing of the driving motor II gear (79) and the rack II (80).