CN112226929B

CN112226929B - Flush joint machine

Info

Publication number: CN112226929B
Application number: CN202011067889.7A
Authority: CN
Inventors: 阮孟定
Original assignee: Zhejiang Duma Sewing Machine Co ltd
Current assignee: Zhejiang Duma Sewing Machine Co ltd
Priority date: 2020-10-07
Filing date: 2020-10-07
Publication date: 2022-11-11
Anticipated expiration: 2040-10-07
Also published as: CN116065307A; CN112226929A

Abstract

The invention discloses a flat sewing machine, and belongs to the technical field of sewing machines. The purpose of the invention is realized by the following steps: a lockstitch sewing machine comprises a frame, wherein a main shaft and a lower shaft are arranged in the frame, and the main shaft and the lower shaft are connected through a synchronous belt; one end of the main shaft is provided with a main motor, and the main motor is used for driving the main shaft to rotate. The invention can transmit the rotation of the main shaft to the lower shaft by connecting the main shaft and the lower shaft through the synchronous belt, has very simple transmission structure and small occupied space, can contain other functional components and can realize the combination with other functional components.

Description

Flat sewing machine

Technical Field

The invention belongs to the technical field of sewing machines, and particularly relates to a flat sewing machine.

Background

At present, the existing flat sewing machine drives the main shaft to rotate through a motor, and then the power is transmitted to the lower shaft, the cloth feeding shaft and the feed lifting teeth shaft through a series of link mechanisms.

However, the structure is still complicated as can be seen from the above structure, and particularly, a plurality of additional functions are required to be added to the existing lockstitch sewing machine. The structure form of pure machinery has the big structure complicacy of occupation space, with the difficult problem of other functional unit cooperations.

Disclosure of Invention

The invention aims to provide a lockstitch sewing machine which can transmit the power of a main motor to a lower shaft by connecting a main shaft and the lower shaft through a synchronous belt.

The purpose of the invention is realized as follows: a lockstitch sewing machine comprises a frame, wherein a main shaft and a lower shaft are arranged in the frame, and the main shaft and the lower shaft are connected through a synchronous belt; one end of the main shaft is provided with a main motor, and the main motor is used for driving the main shaft to rotate.

Preferably, the device also comprises an inner presser foot assembly and an outer presser foot assembly, wherein the upper ends of the inner presser foot assembly and the outer presser foot assembly are provided with an interaction quantity adjusting device of the inner presser foot and the outer presser foot, and the interaction quantity adjusting device comprises a presser foot interaction mechanism which drives the inner presser foot assembly and the outer presser foot assembly to alternately lift and descend; the swinging crank mechanism is used for providing a reciprocating swinging force for the presser foot interaction mechanism; a presser foot lifting crank mechanism for converting the rotary motion of the main shaft into the reciprocating swing required by the swing crank mechanism; and the swinging amount adjusting mechanism is used for adjusting the amplitude of the reciprocating swinging converted by the presser foot lifting crank mechanism.

Preferably, the swing amount adjusting mechanism comprises a driving motor, and an eccentric wheel is mounted on a motor shaft of the driving motor; the wheel surface of the eccentric wheel is abutted with a swinging piece, the other side of the swinging piece is fixedly provided with a transmission shaft, and the other end of the transmission shaft is fixedly connected to a swinging seat of the presser foot lifting crank mechanism.

Preferably, one side of the swinging piece, which is close to the motor shaft, is provided with a strip-shaped groove, the eccentric wheel is arranged in the strip-shaped groove, and the upper side wall and the lower side wall of the strip-shaped groove abut against the upper side and the lower side of the eccentric wheel at the same time; the transmission shaft and the main shaft are arranged in parallel.

Preferably, the presser foot interaction mechanism comprises a lifting seat, a lifting bracket, an inner presser foot assembly and an outer presser foot assembly; the lifting seat is arranged on the lifting support, an external pressure foot rod is arranged on the rear side of the lower part of the lifting seat, and an internal pressure foot rod is arranged on the front side of the lower part of the lifting seat; the rear side of the lower part of the lifting seat, the lifting support and the upper end of the external pressure foot rod are coaxially hinged; the front side of the lower part of the lifting seat is hinged with the upper end of the inner pressure foot rod.

Preferably, the swing crank mechanism comprises an intermediate shaft, and a swing crank is sleeved in the middle of the intermediate shaft; a lifting crank is arranged at one end of the intermediate shaft extending to the presser foot interaction mechanism; the lifting crank drives the lifting seat to rotate through the push-pull rod.

Preferably, the presser foot lifting crank mechanism comprises a swing seat, a first supporting arm and a second supporting arm are respectively arranged on two sides of the swing seat; a first limit connecting rod, a first transmission connecting rod, an output end of a main shaft crank, an input end of a swing crank, a second transmission connecting rod and a second limit connecting rod are sequentially arranged between the first supporting arm and the second supporting arm; the front end of the first support arm is hinged with the front end of a first limiting connecting rod, the front end of the second support arm is hinged with the front end of a second limiting connecting rod, and the rear end of the first limiting connecting rod, the rear end of the second limiting connecting rod, the rear end of the first transmission connecting rod, the rear end of the second transmission connecting rod and the output end of the main shaft crank are coaxially hinged; the input end of the swing crank, the front end of the first transmission connecting rod and the front end of the second transmission connecting rod are coaxially hinged; the output end of the main shaft crank and the input end of the swing crank are both arranged between the first transmission connecting rod and the second transmission connecting rod.

Preferably, a swinging reversing mechanism and a backward and forward seam driving motor are arranged outside the main shaft; the swing reversing mechanism is used for converting the rotary motion of the main shaft into reciprocating swing required by the cloth feeding shaft; the pressure foot motor shaft of the backward and forward seam driving motor drives a swing reversing mechanism through a crank component, and the swing reversing mechanism uses a backward and forward seam middle shaft as a center to carry out swing adjustment.

Preferably, the crank assembly comprises: the motor shaft is provided with a reverse and forward seam eccentric wheel and an eccentric connecting rod, the reverse and forward seam eccentric wheel is installed on the motor shaft, one end of the eccentric connecting rod is sleeved on the reverse and forward seam eccentric wheel, the other end of the eccentric connecting rod is hinged with a swing arm, and the other end of the swing arm is fixed on a reverse and forward seam intermediate shaft.

Preferably, the swing reversing mechanism comprises a swing block, two sides of which are respectively provided with a first swing supporting arm and a second swing supporting arm; a first swing limiting connecting rod, a first swing transmission connecting rod, an output end of a main shaft crank, an input end of a swing crank, a second swing transmission connecting rod and a second swing limiting connecting rod are sequentially arranged between the first swing supporting arm and the second swing supporting arm;

the front end of the first swing supporting arm is hinged with the front end of a first swing limiting connecting rod, the front end of the second swing supporting arm is hinged with the front end of a second swing limiting connecting rod, and the rear end of the first swing limiting connecting rod, the rear end of the second swing limiting connecting rod, the rear end of a first swing transmission connecting rod, the rear end of the second swing transmission connecting rod and the output end of a main shaft crank are coaxially hinged; the input end of the backward and forward seam swinging crank, the front end of the first swinging transmission connecting rod and the front end of the second swinging transmission connecting rod are coaxially hinged; the output end of the main shaft crank and the input end of the swing crank are both arranged between the first swing transmission connecting rod and the second swing transmission connecting rod; the lower end of the backward and forward seam swinging crank is hinged with a transverse pull rod, the other end of the transverse pull rod is hinged with a rotating crank, and a cloth feeding shaft is sleeved in the rotating crank.

Preferably, the sewing machine further comprises a presser foot lifting device, wherein the presser foot lifting device comprises a presser foot lifting support assembly which is arranged at the head of the frame of the sewing machine; the lifting shaft assembly is arranged in a cross beam of the frame and used for lifting or putting down the presser foot lifting support assembly, and the presser foot lifting motor is arranged on the frame and used for driving the lifting shaft assembly; a rotating disc which is arranged on a presser foot motor shaft of the presser foot lifting motor; a curved surface stroke part is arranged on the rotating disc, and the curvature of the contour line of the curved surface stroke part is gradually increased; one end of the linkage crank is fixedly arranged on a presser foot lifting shaft of the lifting shaft assembly, and the other end of the linkage crank is provided with a driven pin shaft; the driven pin shaft is pressed on the curved surface stroke part.

Preferably, the curved surface stroke part is an inner groove formed on the rotating disc, or the curved surface stroke part is an outer contour of the rotating disc; at least one part of the curved surface stroke part is a spiral line, and the spiral line takes the axis of the presser foot motor shaft as the center; a swing arm torsion spring is sleeved outside the presser foot lifting shaft and comprises a first pressure rod and a second pressure rod, and the first pressure rod is abutted against the inner side wall of the frame; the second pressure lever is arranged on the presser foot lifting shaft and synchronously rotates with the presser foot lifting shaft; a pressure lifting swing arm is sleeved outside the pressure foot lifting shaft and synchronously rotates with the pressure foot lifting shaft; the second pressure lever is abutted against the upper end face of the pressure lifting swing arm; the pressure lifting swing arm comprises a pressure wheel part and a limiting part, and the pressure wheel part is arranged between the rotating cam and the second pressure rod; the second pressure lever is arranged between the pressure wheel part and the limiting part; a pressure foot wrench is further arranged on the outer side of the rack, one end of the pressure foot wrench is connected with a wrench shaft, a rotating cam is sleeved at the outer end of the wrench shaft, and the outer edge of the rotating cam abuts against the pressure lifting swing arm; the end face of the rotating cam is provided with a plurality of mounting holes, the mounting holes are used for being connected with the wrench shaft, and the wrench shaft is connected with different mounting holes so as to drive the presser foot lifting shaft to rotate by different radians; one end of the pressure foot wrench is formed with a connecting shaft part, and the wrench shaft is sleeved in the connecting shaft part; a wrench torsion spring is sleeved outside the connecting shaft part and comprises a third pressure rod and a fourth pressure rod, and the third pressure rod penetrates through the pressure foot wrench; the fourth pressure lever penetrates through the rack;

one end of the presser foot lifting shaft is sleeved with a lifting swing arm and synchronously rotates along with the presser foot lifting shaft; the presser foot lifting support assembly comprises a lifting frame, and the lower end part of the lifting frame is connected with a presser foot rod; one side of the lifting frame is extended and formed with a supporting part, and the lifting swing arm is supported against the lower end face of the supporting part.

Preferably, the winding device further comprises a winding device, the winding device comprises a tension wheel assembly arranged in the rack, the tension wheel assembly is provided with a roller part, and the roller part abuts against the synchronous belt and rotates along with the synchronous belt; a friction surface is arranged on the front side of the roller part; the front part of the rack is also provided with a winding mechanism, and a winding shaft of the winding mechanism extends into the rack and is provided with a friction wheel; the winding mechanism has an operating state and a non-operating state: when the winding mechanism is in a working state, the friction wheel is abutted against the friction surface and is driven; when the winding mechanism is in a non-working state, the friction wheel is separated from the friction surface. One end of the roller part is connected with an adjusting shaft, and the adjusting shaft and the roller part synchronously rotate; the adjusting shaft and the roller part are eccentrically arranged, and the adjusting shaft is used for driving the roller part to eccentrically rotate through self rotation so as to adjust the tensioning degree; and a connecting hole is formed in one end of the adjusting shaft, a connecting shaft is arranged in the connecting hole, and the connecting shaft sequentially penetrates through the roller part and the adjusting shaft and is connected with the adjusting shaft through the connecting hole.

Compared with the prior art, the invention has the outstanding and beneficial technical effects that:

1. the main shaft and the lower shaft are connected through the synchronous belt, so that the rotation of the main shaft can be transmitted to the lower shaft, the transmission structure is very simple, the occupied space is small, other functional components can be accommodated, and the combination with other functional components can be realized.

Drawings

FIG. 1 is a schematic view of the overall construction of the lockstitch sewing machine of the present invention; FIG. 2 is an enlarged view of the presser foot wrench and associated components; FIG. 3 is an enlarged view of the lift and press swing arm and associated components; FIG. 4 is a schematic view of the foot lift of the present invention; FIG. 5 is a second schematic view of the foot lift of the present invention; FIG. 6 is a third schematic view of the foot lift of the present invention; FIG. 7 is a schematic view of the construction of the rotating disk;

FIG. 8 is a schematic view of the inner and outer presser foot interaction amount adjusting device; FIG. 9 is a second schematic view of the inner and outer presser foot interaction amount adjusting device; fig. 10 is a schematic view of a presser foot interaction mechanism; FIG. 11 is a schematic view of a presser foot lift crank mechanism; FIG. 12 is a second schematic view of the presser foot lift crank mechanism; FIG. 13 is one of the schematic views of the presser foot lift crank mechanism; FIG. 14 is a second schematic diagram of a presser foot lift crank mechanism;

FIG. 15 is a schematic view of the second embodiment; FIG. 16 is a schematic view of FIG. 15 after components such as a reverse/forward stitch drive motor are hidden; FIG. 17 is a schematic view of the construction of the oscillating reverser; FIG. 18 is an exploded view of the oscillating reverser; FIG. 19 is one of the schematic diagrams of the switching between the normal sewing and the reverse sewing; FIG. 20 is a second schematic view of the switch between the forward and reverse stitches;

FIG. 21 is a schematic structural view of a fourth embodiment; FIG. 22 is a schematic view of a second embodiment; FIG. 23 is a schematic diagram of the operation of the winding mechanism and the tension roller assembly; fig. 24 is a partial enlarged view of the winding mechanism and tensioner assembly of fig. 22; fig. 25 is an exploded view of a tension wheel assembly.

In the figure: 1-a drive motor; 2-eccentric wheel; 3-a pendulous member; 4-a main shaft; 5-lower shaft; 6-synchronous belt; 7-intermediate shaft; 8-lifting the crank; 9-lifting the support; 10-a lifting seat; 11-an outer presser foot assembly; 12-an inner presser foot assembly; 13-a push-pull rod; 14-a pin shaft; 15-a connecting shaft; 16-a motor shaft; 17-a drive shaft; 18-a first articulated shaft; 19-a second articulated shaft; 20-a third hinge axis; 23-axis; 24-axis; 25-a connecting shaft; 26-a mounting frame; 27-upper shaft hole; 28-lower shaft hole; 31-a strip groove; 51-a swing seat; 52-a first support arm; 53-a first limit link; 54-a first drive link; 55-a swing crank; 56-a second limiting connecting rod; 57-a second support arm; 58-a second drive link; 97-main motor; 98-a base; 99-a frame; 100-a crank assembly; 101-presser foot lifting shaft; 102-a feed beam; 103-a reverse and forward seam driving motor; 104-main shaft crank; 105-a backward and forward seam swinging crank; 106-crank rotation; 107-tie rods; 108-eccentric link; 109-swing arm; 110-a reverse and forward seam motor shaft; 111-reverse and forward sewing eccentric wheel; 112-reverse and forward seam intermediate shaft; 113-output end of main shaft crank; 114-input of the oscillating crank; 200-a swing reversing mechanism; 216-a wobble block; 217-a second swing support arm; 218-a second swing limit link; 219-a second swing drive link; 220-a first swing drive link; 221-a first swing support arm; 222-a first swing limit link; 400-a swing amount adjusting mechanism; 500-presser foot lifting crank mechanism; 560-mainshaft lift crank; 600-a presser foot interaction mechanism; 700-a rocking crank mechanism; 61-wrench shaft; 62-a connecting shaft portion; 63-wrench torsion spring; 64-a third compression bar; 65-a fourth strut; 71-mounting holes; 81-a press wheel part; 82-a limiting part; 801-presser foot lift bracket assembly; 802-presser bar; 803-lifting the swing arm; 804-lifting the shaft assembly; 805-a presser foot wrench; 806-rotating the cam; 807-lifting and pressing the swing arm; 808-a linked crank; 809-rotating disk; 810-presser foot lift motor; 811-curved surface stroke; 812-presser foot motor shaft; 813-driven pin shaft; 814-a helix; 815-a hoisting frame; 816-an abutment; 817-presser foot lifting shaft; 818-swing arm torsion spring; 819-a first pressure bar; 820-a second compression bar; 821-wrench shaft; 901-a winding mechanism; 902-a tension wheel assembly; 903-upper synchronizing wheel; 904-a friction wheel; 905-a winding base; 906-lower sync wheel; 907-winding reel; 908-a bobbin; 909-support seat; 910-toggle wrench; 911-roller part; 912-friction surface; 913-a connecting shaft; 914-an adjustment shaft; 915-connecting hole; 916-connecting the bearing; 917-power-assisted hole.

Detailed Description

The invention is further described below in terms of specific examples.

The first embodiment is as follows: as shown in fig. 1 to 14, a flat sewing machine comprises a frame 99, wherein a main shaft 4 and a lower shaft 5 are arranged in the frame, and the main shaft 4 and the lower shaft 5 are connected through a synchronous belt 6; one end of the main shaft 4 is provided with a main motor 97, and the main motor 97 is used for driving the main shaft 4 to rotate. The flat sewing machine further comprises an inner presser foot assembly 12 and an outer presser foot assembly 11, and an interaction amount adjusting device of the inner presser foot and the outer presser foot is arranged at the upper ends of the inner presser foot assembly 12 and the outer presser foot assembly 11.

The interaction amount adjusting device of the inner presser foot and the outer presser foot comprises a presser foot interaction mechanism 600 which drives the inner presser foot assembly 12 and the outer presser foot assembly 11 to alternately lift and descend; a rocking crank mechanism 700 for providing a reciprocating rocking force to the presser foot interaction mechanism 600; a presser foot lifting crank mechanism 500 for converting the rotational motion of the main shaft 4 into the reciprocating swing required by the swing crank mechanism 700; and a swing amount adjusting mechanism 400 for adjusting the amplitude of the reciprocating swing converted by the presser foot lift crank mechanism 500.

The present embodiment adjusts the amplitude of the rotation of the presser foot lift crank mechanism 500 through the swing amount adjustment mechanism 400 to finally adjust the amount of interaction between the inner presser foot assembly 12 and the outer presser foot assembly 11 through the presser foot interaction mechanism 600 via the swing crank mechanism 700.

The structure of the oscillation amount adjusting mechanism 400 will be described in detail below. As shown in fig. 10, the swing amount adjusting mechanism 400 includes a driving motor 1, and an eccentric wheel 2 is mounted on a motor shaft 16 of the driving motor 1; a swinging piece 3 is abutted on the wheel surface of the eccentric wheel 2; in the present embodiment, the oscillating piece 3 is shaped as a fork as a whole, and the eccentric 2 is disposed in the fork.

Furthermore, a strip-shaped groove 31 is formed in one side, close to the motor shaft, of the swinging piece 3, the eccentric wheel 2 is arranged in the strip-shaped groove 31, and the upper side wall and the lower side wall of the strip-shaped groove 31 abut against the upper side and the lower side of the eccentric wheel at the same time; as shown in fig. 10, a transmission shaft 17 is fixedly arranged on the other side of the swinging member 3, and the transmission shaft 17 is arranged in parallel with the main shaft 4. Such a design enables the drive shaft 17 to be rotated through a corresponding angle even when the drive motor 1 is rotated through a small angle.

In the embodiment, the driving motor 1 preferably adopts a stepping motor, and can be controlled more accurately by matching with an electric control system. The accuracy is not only the adjustment of the size of the interaction quantity, but also the accuracy of the adjustment time point, and the automatic adjustment can be realized by controlling the starting and the stopping of the motor according to the actual situation.

The other end of the transmission shaft 17 is fixedly connected to the swing base 51 of the presser foot lift crank mechanism 500. Thereby after driving motor 1 rotates certain angle, can drive the rotation of eccentric wheel 2, then oscillating piece 3 also can follow the swing, because transmission shaft 17 is the swing center of oscillating piece 3, the swing of oscillating piece 3 can be transformed into the rotation of transmission shaft 17, and then oscillating seat 51 also follows the swing.

In this embodiment, one end of the transmission shaft 17 extends into the swing seat 51, and then the other end of the transmission shaft 17 is arranged in a similar way, and the transmission shaft passes through the swing seat 51 through a fastening piece and abuts against the end of the transmission shaft 17 to realize linkage between the two.

Next, the structural design of the swing seat 51 after swinging will be specifically described. Preferably, the presser foot lifting crank mechanism 500 includes a swing seat 51 having a first support arm 52 and a second support arm 57 respectively disposed at both sides thereof; as shown in fig. 11, the swing base 51 is provided at both sides in the longitudinal direction thereof. Also in the present embodiment, the first support arm 52 and the second support arm 57 are each integrally formed with the swing seat 51, which increases the strength of the swing seat 51.

A first limit connecting rod 53, a first transmission connecting rod 54, the output end of a main shaft lifting crank 560, the input end of a swing crank 55, a second transmission connecting rod 58 and a second limit connecting rod 56 are sequentially arranged between the first supporting arm 52 and the second supporting arm 57; the input end of the swing crank 55, the front end of the first transmission connecting rod 54 and the front end of the second transmission connecting rod 58 are coaxially hinged; the front end of the first support arm 52 is hinged to the front end of the first limit link 53, and the hinge is realized by a shaft passing through the front end of the first support arm 52 and the front end of the first limit link 53 at the same time. As shown in fig. 11, the shaft is a first hinge shaft 18.

The front end of the second supporting arm 57 is hinged with the front end of the second limiting link 56, where the hinge is also coaxial, as shown in fig. 11, which is also the first hinge shaft 18.

The rear end of the first limit connecting rod 53, the rear end of the second limit connecting rod 56, the rear end of the first transmission connecting rod 54, the rear end of the second transmission connecting rod 58 and the output end of the main shaft lifting crank 560 are coaxially hinged, and the shaft is a third hinge shaft 20; the output of the spindle lift crank 560 and the input of the swing crank 55 are both disposed between the first drive link 54 and the second drive link 58.

The output end of the main shaft lifting crank 560 rotates synchronously with the third hinge shaft 20 through a fastener. Specifically, as shown in fig. 11 and 12, the output end of the main shaft lifting crank 560, the rear end of the first transmission link 54, and the rear end of the second transmission link 58 are coaxially hinged by the third hinge shaft 20; the front end of the first transmission connecting rod 54, the front end of the second transmission connecting rod 58 and the input end of the swinging crank 55 are coaxially hinged through a second hinge shaft 19.

In the present embodiment, through the above-mentioned series of transmission processes, the initial angle of the swing seat 51 is adjusted, so as to change the interaction amount, thereby adjusting the interaction amount. The specific process is that firstly, the driving motor 1 rotates to drive the adjusting swing seat 51 to swing, and then the first limiting connecting rod 53 and the second limiting connecting rod 56 swing.

Then the main shaft of the lockstitch sewing machine rotates to drive the output end of the main shaft lifting crank 560 to rotate, and the output end of the main shaft lifting crank 560 can do reciprocating motion due to eccentricity; because the output end of the main shaft lifting crank 560 and the input end of the swing crank 55 are both disposed between the first transmission link 54 and the second transmission link 58, the relative distance between the input end of the corresponding swing crank 55 and the output end of the main shaft lifting crank 560 is fixed; similarly, the relative distances between the front ends of the first support arm 52 and the second support arm 57 and the output end of the spindle lifting crank 560 are fixed.

Therefore, as shown in fig. 13, the third hinge shaft 20 rotates around the first hinge shaft 18 as a center thereof, and reciprocates left and right corresponding to the second hinge shaft 19, respectively. Thereby, the swing of the input end of the swing crank 55 can be driven, and the intermediate shaft 7 is driven to rotate, so that the inner presser foot and the outer presser foot are driven to swing.

Therefore, corresponding to different positions of the rotation of the driving motor 1, the initial positions of the first supporting arm 52 and the second supporting arm 57 are changed, that is, the initial position of the first articulated shaft 18 is changed, because the movement stroke of the second articulated shaft 19 is changed, and the purpose of adjusting the interaction amount of the inner presser foot and the outer presser foot is finally achieved.

Preferably, as shown in fig. 8, the swing crank mechanism 700 includes an intermediate shaft 7, and a swing crank 55 is sleeved on the intermediate shaft 7; a lifting crank 8 is arranged at one end of the intermediate shaft 7 extending to the presser foot interaction mechanism 600; the lifting crank 8 drives the lifting seat 10 to rotate through a push-pull rod 13. In this embodiment, the swing crank 55 passes through the upper and lower openings of the crank through the fastening member to clamp the intermediate shaft 7, so that the rotation of the swing crank 55 is changed into the rotation of the intermediate shaft 7, and then the lifting crank 8 swings accordingly, and finally the rotation of the lifting seat 10 is realized through the push-pull rod 13.

The structural design of the presser foot interaction mechanism 600 will be described in detail below. As shown in fig. 10, preferably, the presser foot interaction mechanism 600 includes a lifting base 10, a lifting bracket 9, an inner presser foot assembly 12, an outer presser foot assembly 11; as shown in fig. 9, the lifting seat 10 is disposed on the lifting support 9, and an external pressure foot bar is disposed at the rear side of the lower portion of the lifting seat 10, and an internal pressure foot bar is disposed at the front side of the lower portion of the lifting seat 10; the rear side of the lower part of the lifting seat 10, the lifting support 9 and the upper end of the external pressure foot bar are coaxially hinged; the front side of the lower part of the lifting seat 10 is hinged with the upper end of the inner presser foot rod.

Therefore, the inner presser foot assembly 12 and the outer presser foot assembly 11 can be driven to alternately lift and descend through the action of the lifting support 9, and the function of three-synchronization is realized.

In this embodiment, the lifting seat 10 is triangular, the upper end thereof is hinged to the push-pull rod 13 through a pin 14, two sides of the lower end thereof are respectively hinged to the outer presser bar through a connecting shaft 15, and the other side thereof is similarly hinged to the inner presser bar. At this time, as shown in fig. 10, when the push-pull rod 13 is pulled to the left, the outer presser foot rod is lowered, and the inner presser foot rod is lifted; on the contrary, when the push-pull rod 13 is pushed to the right side, the outer presser bar is lifted, and the inner presser bar is lowered. Thus, in alternation, a tri-synchronous design is formed.

Example two: as shown in fig. 15-20, the flat sewing machine further comprises a cloth feeding shaft 102 and a presser foot lifting shaft 101. In the flat bed sewing machine, the feed shaft 102 is rotated forward and backward to thereby realize the backstitch and the forward stitch of the flat bed sewing machine. The backstitch and forward-stitch adjusting devices of the present embodiment will be described in detail below. The backstitch and forward-stitch adjusting device comprises a swing reversing mechanism 200, and is used for converting the rotary motion of the main shaft 4 into reciprocating swing required by the cloth feeding shaft 102; the backward and forward sewing driving motor 103, its backward and forward sewing motor shaft 110 drives the swing reversing mechanism 200 through the crank assembly 100, the swing reversing mechanism 200 uses the backward and forward sewing intermediate shaft 112 as the center to perform swing adjustment.

The structural design of the crank assembly 100 is described in detail below. Preferably, the crank assembly 100 comprises: the motor shaft is provided with a backward and forward seam eccentric wheel 111 and an eccentric connecting rod 108, the backward and forward seam eccentric wheel 111 is installed on the motor shaft, one end of the eccentric connecting rod 108 is sleeved on the backward and forward seam eccentric wheel 111, the other end of the eccentric connecting rod 108 is hinged with a swing arm 109, and the other end of the swing arm 109 is fixed on a backward and forward seam intermediate shaft 112.

The reverse and forward seam eccentric wheel 111 is installed on the motor shaft, and one end of the eccentric connecting rod 108 is sleeved on the reverse and forward seam eccentric wheel 111, so that the swing arm 109 can swing in a reciprocating manner, and the reverse and forward seam intermediate shaft 112 can rotate in a reciprocating manner. The swing amplitude of the swing reversing mechanism 200 can be adjusted by reciprocating rotation of the reverse and forward seam intermediate shaft 112, so that the reciprocating swing amplitude of the cloth feeding shaft 102 can be adjusted.

Preferably, the swing reversing mechanism 200 includes a swing block 216, both sides of which are respectively provided with a first swing supporting arm 221 and a second swing supporting arm 217;

a first swing limiting connecting rod 222, a first swing transmission connecting rod 220, an output end 113 of a main shaft crank, an input end 114 of a swing crank, a second swing transmission connecting rod 219 and a second swing limiting connecting rod 218 are sequentially arranged between the first swing supporting arm 221 and the second swing supporting arm 217;

the front end of the first swing support arm 221 is hinged with the front end of a first swing limit connecting rod 222, the front end of the second swing support arm 217 is hinged with the front end of a second swing limit connecting rod 218, and the rear end of the first swing limit connecting rod 222, the rear end of the second swing limit connecting rod 218, the rear end of a first swing transmission connecting rod 220, the rear end of a second transmission connecting rod 18 and the output end 31 of the main shaft crank 104 are all hinged coaxially 24;

the input end of the forward and backward sewing swing crank 105, the front end of the first swing transmission connecting rod 220 and the front end of the second swing transmission connecting rod 219 are coaxially hinged 23; the output end 113 of the spindle crank and the input end 114 of the swing crank are both disposed between the first swing drive link 220 and the second swing drive link 219.

The operation of the wobble mechanism 200 will be described in detail below. After the counter-clockwise middle shaft 112 rotates, the swinging block 216 is driven to swing.

In this embodiment, the swing block 216, the second swing support arm 217 and the first swing support arm 221 are integrally formed, and the swing of the swing block 216 drives the second swing support arm 217 and the first swing support arm 221 to swing.

Thereby driving the rotation of the first swing limiting link 222 and the second swing limiting link 218, so as to change the initial angle of the first swing limiting link 222 and the second swing limiting link 218, thereby changing the needle pitch and realizing the adjustment of the backstitch and the forward stitch.

In addition, the main shaft crank 104 and the main shaft 4 are also in an eccentric structure. The output 113 of the spindle crank thus performs a reciprocating lifting movement when the spindle 4 is rotated.

As shown in fig. 19-20, the shaft 24 rotates around the connecting shaft 25, i.e. there are two movement direction trends of X1 or X2, so that the driving shaft 23 can move toward Y1 or Y2, and a rotating fulcrum is formed because the shaft 23 is sleeved in the input end 114 of the swing crank.

In addition, in practical use, when the driving motor rotates by a certain angle, the second swing supporting arm 217 and the first swing supporting arm 221 do not swing any more after swinging by a certain angle, and at this time, the connecting shaft 25 is fixed, so that the shaft 24 can rotate around the connecting shaft 25.

In addition, because the

shafts

23, 24 and 25 are connected oppositely through fixed-length rods or swing arms, the distance between each two is fixed relatively.

It is thus achieved that the shaft 23 has a tendency to move in different directions when the connecting shaft 25 is in different positions, as shown in fig. 19-20.

Also shown in the figures are the shaft 23, the shaft 24 and the connecting shaft 25, but in application to the whole structure, the final effect is the movement of the input end 114 of the oscillating crank.

Therefore, an upper shaft hole 27 and a lower shaft hole 28 are correspondingly formed at the upper end and the lower end of the backward and forward seam swinging crank 105 respectively, a presser foot lifting shaft 101 is sleeved in the upper shaft hole 27, a cross pull rod 107 is sleeved in the lower shaft hole 28, the cross pull rod 107 is connected with a rotating crank 106, and the adjusting cloth feeding shaft 102 rotates through the rotating crank 106, so that the backward and forward seams are realized. The lower end of the forward and backward oscillating crank 105 is thus articulated to the tie rod 107.

The other end of the cross pull rod 107 is hinged with a rotating crank 106, and the rotating crank 106 is internally sleeved with the adjusting cloth feeding shaft 102. And then the direction of the presser foot feeding is changed by adjusting the different rotating directions of the cloth feeding shaft 102, thereby realizing the functions of backstitch and forward stitch.

Example three: as shown in fig. 1-7, a flat seamer comprises a frame 99, one end of the frame 99 is provided with an outer presser foot assembly 11 and an inner presser foot assembly 12, both the outer presser foot assembly 11 and the inner presser foot assembly 12 comprise presser foot rods 802; a presser foot lift is also provided within the frame 99. The presser foot lifting device comprises a presser foot lifting bracket component 801 which is arranged at the head of the frame 99 of the flat sewing machine; the function of the presser foot lift bracket assembly 801 is to connect with the presser foot assembly 1 and ultimately lift the presser foot.

A lift shaft assembly 804 mounted in a cross beam of the frame 99 for raising and lowering the presser foot lift bracket assembly 801, the lift shaft assembly 804 driving movement of the lift bracket assembly 2 by rotation in this embodiment.

A presser foot lift motor 810 mounted on the frame 99 for driving the lift shaft assembly 804; a rotating disc 809 mounted on a presser foot motor shaft 812 of the presser foot lift motor 810; the rotating disc 809 is provided with a curved surface stroke part 811, and the curvature of the contour line of the curved surface stroke part 811 is gradually increased; one end of the linkage crank 808 is fixedly arranged on a presser foot lifting shaft 817 of the lifting shaft assembly 804, and the other end is provided with a driven pin roll 813; the follower pin 813 abuts against the side wall of the curved surface stroke portion 811.

Therefore, the curvature of the contour line of the curved surface stroke portion 811 gradually increases, and the adjustment of the change rate can be realized. Specifically speaking, through the increase of contour line camber, can let after the motor rotated certain fixed angle for linkage crank 808 can pivoted a bigger angle, and the speed that changes also can increase moreover, thereby can both let the presser foot have trafficability characteristic to the cloth of different thickness. Additionally, the axis of the follower pin shaft 813 is in a parallel position, rather than collinear, with the axis of the presser foot motor shaft 812.

Therefore, the presser foot lifting motor 810 rotates to drive the driven pin shaft 813 to rotate in the curved stroke part 811, and then the presser foot lifting shaft 817 rotates to further lift the presser foot lifting support assembly 801. The specific implementation mode is as follows: firstly, in actual use, the presser foot lifting motor 810 is connected with an electric control system, and then the rotating angle of the presser foot lifting motor 810 is controlled, so that the height of the presser foot lifting can be adjusted according to actual conditions; the automatic presser foot lifting can be realized by controlling the starting and stopping time of the presser foot lifting motor 810.

Preferably, the curved stroke 811 is an inner groove formed on the rotating disc 809. The contour curve of at least a part of the wall surface of the curved surface stroke portion 811 is a spiral line 814, and the spiral line 814 is centered on the axis of the presser foot motor shaft 812.

Preferably, a swing arm torsion spring 818 is sleeved outside the presser foot lifting shaft 817, the swing arm torsion spring 818 comprises a first pressing rod 819 and a second pressing rod 820, and the first pressing rod 819 abuts against the inner side wall of the frame 99; the second press lever 820 is provided on a presser foot lifting shaft 817 and rotates in synchronization with the presser foot lifting shaft 817. This technical scheme specifically discloses a technical scheme that can drive presser foot lift shaft 817 and reset.

In this embodiment, a swing arm torsion spring 818 is sleeved outside the presser foot lifting shaft 817, and the second pressing rod 820 is arranged on the presser foot lifting shaft 817 and rotates synchronously with the presser foot lifting shaft 817 to cause the swing arm torsion spring 818 to deform, and then the first pressing rod 819 abuts against the inner side wall of the frame 99, so as to provide a reaction force, thereby resetting the presser foot lifting shaft 817.

In this embodiment, a lifting and pressing swing arm 807 is sleeved outside the presser foot lifting shaft 817, and the lifting and pressing swing arm 807 and the presser foot lifting shaft 817 rotate synchronously; the second pressing rod 820 abuts against the upper end face of the lifting swing arm 807. The synchronous rotation of the lifting and pressing swing arm 807 and the presser foot lifting shaft 817 is realized by punching a hole on the lifting and pressing swing arm 807 in the radial direction of the presser foot lifting shaft 817 and by penetrating the hole with a fastener.

Preferably, the pressure lifting swing arm 807 comprises a pressure wheel part 81 and a limiting part 82, wherein the pressure wheel part 81 is arranged between the rotating cam 806 and the second pressure rod 820; the second pressing rod 820 is arranged between the pressing wheel part 81 and the limiting part 82.

Preferably, the entire shape of the pressing wheel portion 81 is "7" shaped, and the rotating cam 806 abuts against the inner side of the pressing wheel portion 81. Preferably, a pressure foot wrench 805 is further arranged on the outer side of the machine frame 99, one end of the pressure foot wrench 805 is connected with a wrench shaft 61, a rotating cam 806 is sleeved at the outer end of the wrench shaft 61, and the outer edge of the rotating cam 806 abuts against a pressure lifting swing arm 807; the rotating cam 806 is disposed within the housing 99.

Therefore, the presser foot lifting shaft 817 is rotated by rotating the presser foot wrench 805 to rotate the wrench shaft 61, the rotating cam 806 is rotated by rotating the wrench shaft 61, and then the rotating cam 806 is used to drive the presser foot lifting swing arm 807 to rotate, so that the presser foot lifting shaft 817 is rotated finally, and the function of manually lifting the presser foot is realized.

Preferably, the end surface of the rotating cam 806 is formed with a plurality of mounting holes 71, the mounting holes 71 are used for connecting with the wrench shaft 61, and the wrench shaft 61 is connected with different mounting holes 71 to drive the presser foot lifting shaft 817 to rotate by different arcs.

Preferably, a connecting shaft part 62 is formed at one end of the presser foot wrench 805, and the wrench shaft 61 is sleeved in the connecting shaft part 62; a wrench torsion spring 63 is sleeved outside the connecting shaft part 62, the wrench torsion spring 63 comprises a third pressure lever 64 and a fourth pressure lever 65, and the third pressure lever 64 is arranged in the pressure foot wrench 805 in a penetrating manner; the fourth pressure lever 65 is arranged in the frame 99 in a penetrating way.

The above is a technical solution of adding a torsion spring at the position of the pressure foot wrench 805 to assist the reset of the pressure foot wrench 805. Preferably, one end of the presser foot lifting shaft 817 is sleeved with the lifting swing arm 803 and rotates synchronously with the presser foot lifting shaft 817; the presser foot lifting bracket assembly 801 comprises a lifting frame 815, and the lower end part of the lifting frame 815 is connected with a presser foot rod; an abutting part 816 extends from one side of the lifting frame 815 and the lifting swing arm 803 abuts against the lower end face of the abutting part 816.

Example four: as shown in fig. 21 to 25, a flat seamer comprises a frame 99 and a base 98, wherein a main shaft 4 is arranged at the upper part of the frame 99, a lower shaft 5 is arranged at the lower part of the frame 99, and the main shaft 4 and the lower shaft 5 are driven by a synchronous belt 6.

As can be seen from the above, the flat bed sewing machine according to the present invention is applicable to a flat bed sewing machine including a main shaft 4 and a lower shaft 5, wherein the lower shaft 5 is driven by a timing belt 6 between the main shaft 4 and the lower shaft 5. An upper synchronizing wheel 903 and a lower synchronizing wheel 906 are correspondingly arranged on the main shaft 4 and the lower shaft 5 respectively.

One end of the main shaft 4 is provided with a main motor 97, and the rotation of the main motor 97 drives the main shaft 4 and the upper synchronizing wheel 903 to rotate in turn. The winding device comprises a tension wheel assembly 902 arranged in the frame 99, wherein the tension wheel assembly 902 is provided with a roller part 911, and the roller part 911 abuts against the synchronous belt 6 and rotates along with the synchronous belt 6. Specifically, as shown in fig. 21, the roller portion 911 passes through the supporting base 909 from the right side to the left side along the longitudinal direction of the frame 99 and abuts against the timing belt 6, and abuts against the timing belt 6 so as to be rotated by the rotation of the timing belt 6.

A friction surface 912 is arranged on the front side of the roller part 911; the rotation of the roller portion 911 drives the rotation of the friction surface 912. The front part of the rack is also provided with a winding mechanism, and a winding shaft of the winding mechanism 901 extends into the rack 99 and is provided with a friction wheel 904; the winding mechanism 901 has an operating state and a non-operating state: when the winding mechanism is in a working state, the friction wheel 904 abuts against the friction surface 912 and is driven; when the winding mechanism is in a non-working state, the friction wheel 904 is disengaged from the friction surface 912.

The winding device ingeniously applies the rotation of the synchronous belt 6, the roller part 911 of the tension roller assembly 902 is used for bearing the rotation of the synchronous belt 6, and when the winding mechanism is in a working state, the friction wheel 904 abuts against the friction surface 912 to be driven, so that the winding operation of the bobbin can be realized.

The winding mechanism of the present invention creatively changes the position of the winding mechanism from the position of the upper end of the conventional main shaft to the position of the tension roller assembly 902. And because the position is the most common front of the worker in operation, the worker can directly replace the bobbin on the winding mechanism conveniently and intuitively.

The tight pulley assembly 902 that rises described in this embodiment not only has the effect of rising the tight hold-in range, can also let winding mechanism rotate through structural design, realizes giving the bobbin winding automatically.

As shown in fig. 25, preferably, an adjusting shaft 914 is connected to one end of the roller portion 911, and the adjusting shaft rotates synchronously with the roller portion 911; the adjusting shaft 914 is eccentrically arranged with the roller portion 911, and the adjusting shaft 914 is used for driving the roller portion 911 to eccentrically rotate through self-rotation so as to adjust the tensioning degree. The eccentric arrangement of the adjustment shaft 914 and the roller portion 911 according to the present invention means that, in the present embodiment, the axes of the adjustment shaft 914 and the roller portion 911 are parallel to each other and are not coaxially arranged.

Specifically, in the present embodiment, a connection hole 915 is formed at one end of the adjustment shaft 914, and the axis position of the connection hole 915 is not collinear with the adjustment shaft 914. Thus forming an eccentric arrangement between the adjustment shaft 914 and the roller portion 911. A connecting shaft 913 is disposed in the connecting hole 915, and specifically, as shown in fig. 25, a hexagon socket is formed at one end of the connecting shaft 913, and a cylindrical shaft is formed at the other end.

The connecting shaft 913, that is, a cylindrical shaft portion, passes through the roller portion 911 and the adjustment shaft 914 in this order, and is connected to the adjustment shaft 914 through a connecting hole 915. With this arrangement, when the adjustment shaft 914 is rotated, the relative position between the roller portion 911 and the timing belt 6 is changed due to the eccentric arrangement between the roller portion 911 and the adjustment shaft 914.

That is, as shown in fig. 23, the tension pulley assembly 902 functions to move the right side of the timing belt 6 to the left and right.

Also as shown in fig. 21-22, in this embodiment, the adjusting shaft 914 passes through the supporting seat 909 along the length direction of the frame 99 and abuts against the timing belt 6.

The position design not only has the function of tensioning the synchronous belt, but also can not interfere with other parts in the existing lockstitch sewing machine.

Preferably, a connecting bearing 916 is sleeved on the inner side of the roller part 911, and the connecting shaft 913 is inserted into the connecting bearing 916. Preferably, the adjusting shaft 914 has an outer edge formed with a connecting bearing 917 in a radial direction, and the connecting bearing 917 is located outside the housing 99.

Preferably, the winding mechanism 901 includes a winding base 905, a winding shaft 907 penetrates through the winding base 905, and one end of the winding shaft 907 is connected with the friction wheel 904; the other end of the winding shaft 907 penetrates through the winding base 905 and extends out of the winding base 905 to form a connecting end, and the connecting end is used for sleeving the shuttle core 908.

The outside of said link is provided with stirs the spanner 910, stir the spanner 910 and is used for letting the winding mechanism switch between non-working condition and working condition. How to implement the handover specifically belongs to the prior art, and is not described herein in detail.

The above embodiments are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited thereby, so: equivalent changes made according to the structure, shape and principle of the invention shall be covered by the protection scope of the invention.

Claims

1. A lockstitch sewing machine is characterized in that: the device comprises a rack, wherein a main shaft (4) and a lower shaft (5) are arranged in the rack, and the main shaft (4) and the lower shaft (5) are connected through a synchronous belt (6); one end of the main shaft (4) is provided with a main motor, and the main motor is used for driving the main shaft (4) to rotate;

the lockstitch sewing machine further comprises a presser foot lifting device, and the presser foot lifting device comprises:

a presser foot lifting bracket assembly (801) which is arranged at the head of a frame (99) of the flat sewing machine;

a lifting shaft assembly (804) mounted in a cross beam of the frame (99) for lifting or lowering the presser foot lift bracket assembly (801);

a presser foot lift motor (810) mounted on the frame (99) for driving the lift shaft assembly (804);

the lifting shaft assembly (804) at least comprises a presser foot lifting shaft (817);

a swing arm torsion spring (818) is sleeved outside the presser foot lifting shaft (817), the swing arm torsion spring (818) comprises a first pressure rod (819) and a second pressure rod (820), and the first pressure rod (819) abuts against the inner side wall of the rack (99); the second pressure lever (820) is arranged on a presser foot lifting shaft (817) and rotates synchronously with the presser foot lifting shaft (817);

a lifting and pressing swing arm (807) is sleeved outside the presser foot lifting shaft (817), and the lifting and pressing swing arm (807) and the presser foot lifting shaft (817) synchronously rotate; the second pressure lever (820) abuts against the upper end face of the lifting and pressing swing arm (807);

a pressure foot wrench (805) is further arranged on the outer side of the rack (99), one end of the pressure foot wrench (805) is connected with a wrench shaft (61), a rotating cam (806) is sleeved at the outer end of the wrench shaft (61), and the outer edge of the rotating cam (806) abuts against a pressure lifting swing arm (807);

the presser foot lift arrangement comprises:

a rotating disc (809) mounted on a presser foot motor shaft (812) of the presser foot lift motor (810); a curved surface stroke part (811) is arranged on the rotating disc (809), and the curvature of the contour line of the curved surface stroke part (811) is gradually increased;

one end of the linkage crank (808) is fixedly arranged on a presser foot lifting shaft (817) of the lifting shaft assembly (804), and the other end of the linkage crank is provided with a driven pin shaft (813); the driven pin shaft (813) is pressed on the curved surface stroke part (811);

the curved surface stroke part (811) is an inner groove formed on the rotating disc (809), or the curved surface stroke part (811) is the outer contour of the rotating disc;

the contour curve of at least one part of the curved surface stroke part (811) is a spiral line (814), and the spiral line (814) takes the axis of the presser foot motor shaft (812) as the center;

the pressure lifting swing arm (807) comprises a pressure wheel part (81) and a limiting part (82), and the pressure wheel part (81) is arranged between the rotating cam (806) and the second pressure rod (820); the second pressure lever (820) is arranged between the pressure wheel part (81) and the limiting part (82);

a plurality of mounting holes (71) are formed in the end face of the rotating cam (806), the mounting holes (71) are used for being connected with the wrench shaft (61), and the wrench shaft (61) is connected with different mounting holes (71) so as to drive the presser foot lifting shaft (817) to rotate in different radians;

one end of the pressure foot wrench (805) is formed with a connecting shaft part (62), and the wrench shaft (61) is sleeved in the connecting shaft part (62); a wrench torsion spring (63) is sleeved outside the connecting shaft part (62), the wrench torsion spring (63) comprises a third pressure lever (64) and a fourth pressure lever (65), and the third pressure lever (64) is arranged in the pressure foot wrench (805) in a penetrating manner; the fourth pressure lever (65) is arranged in the rack (99) in a penetrating way;

one end of the presser foot lifting shaft (817) is sleeved with a lifting swing arm (803) and synchronously rotates along with the presser foot lifting shaft (817); the presser foot lifting support assembly (801) comprises a lifting frame (815), and the lower end part of the lifting frame (815) is connected with a presser foot rod (802); an abutting part (816) extends and is formed on one side of the lifting frame (815), and the lifting swing arm (803) abuts against the lower end face of the abutting part (816).

2. The flat seamer of claim 1, further comprising an inner presser foot assembly (12) and an outer presser foot assembly (11), wherein the upper ends of the inner presser foot assembly (12) and the outer presser foot assembly (11) are provided with an inner and outer presser foot interaction amount adjusting device; the interaction amount adjusting device comprises

The presser foot interaction mechanism (600) drives the inner presser foot assembly (12) and the outer presser foot assembly (11) to alternately lift and descend;

a rocking crank mechanism (700) for providing a reciprocating rocking force to the presser foot interaction mechanism (600);

a presser foot lifting crank mechanism (500) for converting the rotational motion of the main shaft (4) into the reciprocating swing required by the swing crank mechanism (700);

and a swing amount adjusting mechanism (400) for adjusting the amplitude of the reciprocating swing converted by the presser foot lifting crank mechanism (500).

3. The lockstitch machine according to claim 2, wherein the swing amount adjusting mechanism (400) comprises a driving motor (1), an eccentric wheel (2) is mounted on a motor shaft of the driving motor (1); a swinging piece (3) is abutted against the wheel surface of the eccentric wheel (2), a transmission shaft (17) is fixedly arranged on the other side of the swinging piece (3), and the other end of the transmission shaft (17) is fixedly connected to a swinging seat (51) of the presser foot lifting crank mechanism (500);

a strip-shaped groove (31) is formed in one side, close to a motor shaft, of the swinging piece (3), the eccentric wheel (2) is arranged in the strip-shaped groove (31), and the upper side wall and the lower side wall of the strip-shaped groove abut against the upper side and the lower side of the eccentric wheel at the same time; the transmission shaft (17) and the main shaft (4) are arranged in parallel;

the presser foot interaction mechanism (600) comprises a lifting seat (10), a lifting support (9), an inner presser foot assembly (12) and an outer presser foot assembly (11); the lifting seat (10) is arranged on the lifting support (9), an external pressure foot bar is arranged on the rear side of the lower part of the lifting seat (10), and an internal pressure foot bar is arranged on the front side of the lower part of the lifting seat (10); the rear side of the lower part of the lifting seat (10), the lifting support (9) and the upper end of the outer pressure foot rod are coaxially hinged; the front side of the lower part of the lifting seat (10) is hinged with the upper end of the inner pressure foot rod;

the swing crank mechanism (700) comprises an intermediate shaft (7), and a swing crank (55) is sleeved in the middle of the intermediate shaft (7); a lifting crank (8) is arranged at one end of the intermediate shaft (7) extending to the presser foot interaction mechanism (600); the lifting crank (8) drives the lifting seat (10) to rotate through a push-pull rod (13).

4. The lockstitch machine according to claim 2, wherein the presser foot lift crank mechanism (500) comprises,

a swing seat (51) provided with a first support arm (52) and a second support arm (57) on both sides thereof;

a first limit connecting rod (53), a first transmission connecting rod (54), the output end of a main shaft lifting crank (560), the input end of a swinging crank (55), a second transmission connecting rod (58) and a second limit connecting rod (56) are sequentially arranged between the first supporting arm (52) and the second supporting arm (57);

the front end of the first supporting arm (52) is hinged with the front end of a first limit connecting rod (53),

the front end of the second supporting arm (57) is hinged with the front end of the second limit connecting rod (56),

the rear end of the first limiting connecting rod (53), the rear end of the second limiting connecting rod (56), the rear end of the first transmission connecting rod (54), the rear end of the second transmission connecting rod (58) and the output end of the main shaft lifting crank (560) are coaxially hinged;

the input end of the swing crank (55), the front end of the first transmission connecting rod (54) and the front end of the second transmission connecting rod (58) are coaxially hinged;

the output end of the main shaft lifting crank (560) and the input end of the swinging crank (55) are arranged between the first transmission connecting rod (54) and the second transmission connecting rod (58).

5. The flat sewing machine according to claim 1, characterized in that a swing reversing mechanism (200) and a backward and forward sewing drive motor (103) are arranged outside the main shaft (4);

the swing reversing mechanism (200) is used for converting the rotary motion of the main shaft (4) into reciprocating swing required by the cloth feeding shaft (102);

the pressure foot motor shaft (812) of the backward and forward sewing driving motor (103) drives the swing reversing mechanism (200) through the crank component (100), and the swing reversing mechanism (200) performs swing adjustment by taking a backward and forward sewing intermediate shaft (112) as a center.

6. The lockstitch machine of claim 5, wherein the crank assembly comprises: the motor shaft is provided with a backward and forward seam eccentric wheel (111) and an eccentric connecting rod (108), the backward and forward seam eccentric wheel (111) is installed on the motor shaft, one end of the eccentric connecting rod (108) is sleeved on the backward and forward seam eccentric wheel (111), the other end of the eccentric connecting rod (108) is hinged with a swing arm (109), and the other end of the swing arm (109) is fixed on a backward and forward seam intermediate shaft (112).

7. The lockstitch machine according to claim 5, characterized in that the oscillating reversing mechanism (200) comprises,

a swing block (216) provided with a first swing support arm (221) and a second swing support arm (217) on both sides thereof;

a first swing limiting connecting rod (222), a first swing transmission connecting rod (220), an output end (113) of the main shaft crank (104), an input end (114) of the swing crank, a second swing transmission connecting rod (219) and a second swing limiting connecting rod (218) are sequentially arranged between the first swing supporting arm (221) and the second swing supporting arm (217);

the front end of the first swing supporting arm (221) is hinged with the front end of a first swing limiting connecting rod (222),

the front end of the second swing supporting arm (217) is hinged with the front end of a second swing limiting connecting rod (218),

the rear end of the first swing limiting connecting rod (222), the rear end of the second swing limiting connecting rod (218), the rear end of the first swing transmission connecting rod (220), the rear end of the second swing transmission connecting rod (219) and the output end (31) of the spindle crank (104) are coaxially (24) hinged;

the input end of the backward and forward seam swinging crank (105), the front end of the first swinging transmission connecting rod (220) and the front end of the second swinging transmission connecting rod (219) are coaxially (23) hinged;

the output end (113) of the main shaft crank (104) and the input end (114) of the swinging crank are both arranged between the first swinging transmission connecting rod (220) and the second swinging transmission connecting rod (219);

the lower end of the backward and forward seam swinging crank (105) is hinged with a transverse pull rod (107), the other end of the transverse pull rod (107) is hinged with a rotating crank (106), and a cloth feeding shaft (102) is sleeved in the rotating crank (106).

8. The lockstitch machine according to claim 1, characterized by further comprising a winding device, wherein the winding device comprises a tension wheel assembly (902) arranged in the frame (99), the tension wheel assembly (902) has a roller part (911), and the roller part (911) abuts against the synchronous belt (6) and rotates along with the synchronous belt;

a friction surface (912) is arranged on the front side of the roller part (911);

the front part of the rack (99) is also provided with a winding mechanism (901), and a winding shaft of the winding mechanism (901) extends into the rack (99) and is provided with a friction wheel (904);

the winding mechanism (901) has an operating state and a non-operating state:

when the winding mechanism (901) is in a working state, the friction wheel (904) is abutted against the friction surface (912) and is driven;

when the winding mechanism (901) is in a non-working state, the friction wheel (904) is separated from the friction surface (912);

one end of the roller part (911) is connected with an adjusting shaft (914), and the adjusting shaft and the roller part (911) synchronously rotate; the adjusting shaft (914) and the roller part (911) are arranged eccentrically, and the adjusting shaft (914) is used for driving the roller part (911) to rotate eccentrically through self rotation so as to adjust the tensioning degree;

a connecting hole (915) is formed in one end of the adjusting shaft (914), a connecting shaft (913) is arranged in the connecting hole (915), and the connecting shaft (913) sequentially penetrates through the roller part (911) and the adjusting shaft (914) and is connected with the adjusting shaft (914) through the connecting hole (915).