Automatic thread tailing device for flat lock sewing machine and method thereof

Abstract

The application discloses a kind of automatic bottom thread connecting devices of flat-stitch sewing equipment, including head, table board, rotating shuttle, thread amount detector, motor winder, bottom thread thread clipper, bottom thread thread cutter and bottom thread thread presser.The application also discloses a kind of automatic bottom thread connecting method of automatic bottom thread connecting device of flat-stitch sewing equipment.The application increases the functions of automatic bottom thread connecting, bottom thread pressing, bottom thread winding and bottom thread cutting under the condition of existing sewing machine functions.When staff complete a clothing production process and need to replace clothing piece or complete specific clothing action, the technology automatically controls each electromagnet, motor and solenoid valve by system host in a very short time to complete the process of automatic thread connecting, automatic thread pressing, automatic thread winding and automatic thread cutting under machine table, which overcomes the defects of low efficiency and high cost of manual bottom thread replacement.

Description

Technical Field

[0001] This invention belongs to the field of garment processing and sewing equipment, specifically relating to an automatic bobbin thread joining device for a flat-seam sewing machine. This invention also relates to a method for automatically joining bobbin threads using this automatic bobbin thread joining device for a flat-seam sewing machine. Background Technology

[0002] Humans cannot live without clothing, food, shelter, and transportation, and clothing production cannot be separated from sewing equipment. Clothing stitching is mainly divided into two types based on the stitch: chain stitch and lockstitch. Sewing equipment capable of producing lockstitch is collectively called a flatbed sewing machine. The flatbed sewing machine described in this invention includes, but is not limited to, flatbed sewing machines and various rotary shuttle flatbed sewing machines such as embroidery machines. Flatbed sewing machines all contain a rotary shuttle, inside which is installed a bobbin with bobbin thread. This bobbin, wound with bobbin thread, is installed inside the bobbin and works in conjunction with the needle for sewing. A drawback of flatbed sewing machines is that after each bobbin has been used up, a second bobbin with bobbin thread must be replaced. Because the bobbin is located inside the rotary shuttle under the sewing table, it is impossible to observe the amount of thread used while sewing. Furthermore, the amount of thread wound on the bobbin is very small. Therefore, when the bobbin thread is used up, the operator cannot notice it in time. This often results in the operator sewing a long distance before realizing there is no bobbin thread left, requiring frequent machine stops to replace the bobbin and re-sew the unused parts. Every time the bobbin thread is used up, the second bobbin with the bobbin thread already wound must be replaced immediately. This not only increases the labor intensity of workers but also reduces production efficiency, increases production costs, and is detrimental to improving the overall economic benefits of the enterprise. Existing technologies basically simulate the manual bobbin thread changing process, such as Chinese invention patent CN201610734226.3 An automatic bobbin thread changing device and method, Chinese invention patent CN201510514290.6 Sewing machine bobbin thread changing mechanism and sewing machine, and Chinese invention patent CN201510050824.4 Automatic bobbin thread changing device, etc. These domestic or foreign patents all simulate the manual bobbin thread changing mode by taking out the empty bobbin case, replacing it with a full bobbin case with the bobbin thread already wound, and then loading it in by machine. However, it does not save much time, and the structure is complex and the cost is too high. The efficiency improvement is also extremely limited. Therefore, it has only been commercially applied in some special models, while a large number of flatbed sewing machines still require manual bobbin thread changing. This invention innovates by eliminating the need to remove the bobbin during the machine's winding process, and by utilizing the time between each operation and fabric piece change to check the bobbin thread allowance. If the bobbin thread is insufficient, the machine completes the clamping, splicing, winding, and cutting operations during the interval between changing fabric pieces. The entire process is automated, fast, and efficient, significantly improving work efficiency. Furthermore, this invention is low-cost, meets the needs of commercial production, and is conducive to market promotion. Summary of the Invention

[0003] The technical problem this invention aims to solve is to overcome the shortcomings of existing technologies and provide an automatic bobbin thread joining device for flat-seam sewing equipment that automatically completes the operations of thread clamping, joining, winding, and cutting. The entire operation is automated, fast, and efficient, effectively improving work efficiency. Furthermore, this invention is low-cost and meets the needs of commercial applications. This invention also provides a method for automatically joining bobbin threads using this automatic bobbin thread joining device for flat-seam sewing equipment.

[0004] The present invention solves the above-mentioned technical requirements through the following technical solutions:

[0005] An automatic bobbin thread splicing device for a flat-seam sewing machine includes a sewing machine head (2), a table (3), a rotary hook (4), a thread quantity detector (5), a motor winding device (6), a bobbin thread clamp (7), a bobbin thread breaker (8), and a bobbin thread presser (9), characterized in that...

[0006] The sewing machine (1) has its head (2) fixed on the table (3), and a rotary hook (4) is fixed on the shaft of the head (2) located below the table (3).

[0007] The rotary hook (4) is provided with a line quantity detector (5) on its side, and a motor winding device (6) is provided in front of the rotary hook (4). The bottom thread clamping device (9), the bottom thread breaker (8), and the bottom thread clamping device (7) are provided in sequence in front of the rotary hook (4).

[0008] In order to achieve better technical results, the rotary shuttle (4) includes a rotary shuttle core (21), a shuttle shell (25) and a shuttle core (37).

[0009] The rotary shuttle core (21) has an L-shaped shuttle case slot (22) on each of its corresponding inner core walls. A shuttle case opening is provided at the bottom of its inner core wall, and a hidden shuttle case opening (23) is provided at the shuttle case opening. The rotary shuttle core (21) also has a shuttle core post (24) at its center.

[0010] The shuttle shell (25) is a cylindrical body with one end open and the other end closed. Its end face is arc-shaped and has a shuttle shell opening (35). A circular hole (31) is also provided at the center of the end face of the shuttle shell (25). The side wall of the shuttle shell (25) is provided with a reverse-clockwise shuttle skin (32). A thread fixing hole (33) is provided in front of the reverse-clockwise shuttle skin (32). A thread threading hole (34) is provided diagonally above the thread fixing hole (33). The outlet of the thread threading hole (34) is located on the shuttle shell. At the center of the shuttle opening (35) of (25), a probe opening (36) is provided on the lower right side wall of the shuttle (25); a shuttle flap (26) and a lock head (27) are provided on the outer side of the closed end face of the shuttle (25). The lock head (27) is composed of a sliding plate and a spring. One end of the spring is fixed on the shuttle (25). One end of the sliding plate is connected to the spring, and the other end is inserted into the shuttle slot. The shuttle flap (26) is movably connected to the sliding plate through its bottom.

[0011] The outer wall of the shuttle (25) is provided with two locking blocks (39);

[0012] Pulling up the shuttle case trigger (26) causes the lock head (27) to retract into the shuttle case (25). The spindle core (21) presses down the locking block (39) on the outer wall of the shuttle case (25) along the L-shaped shuttle case slot (22) and rotates clockwise. Then, the shuttle case trigger (26) is lowered, and the lock head (27) extends forward under the action of the spring and is locked into the hidden slot (23) of the shuttle case, thus fixing the spindle core (21) inside the shuttle case (25).

[0013] The bobbin (37) consists of two identical disc-shaped end faces and a hollow column (38), with the two ends of the hollow column (38) passing through the center of the two end faces respectively, and fixing the two end faces at its two ends;

[0014] The hollow column (38) of the bobbin (37) is fitted onto the bobbin column (24) and fixed inside the spindle (21);

[0015] The rotary shuttle core (21) is fixed inside the shuttle case (25).

[0016] To achieve better technical results, the bobbin post (24) is 2-10mm long and has an outer diameter of XXmm, and the hollow post (38) of the bobbin (37) has an inner diameter of 4-5mm.

[0017] To achieve better technical results, the spindle core (24) is 2-3 mm long.

[0018] In order to achieve better technical results, the line measuring probe (5) includes a first fixing frame (41), a guide rail seat (42), a displacement sensor (43) and a line measuring probe (44).

[0019] The line measuring probe (5) is fixed to the lower side of the platform (3) by the first fixing frame (41). The first fixing frame (41) can be freely adjusted in the up, down, left and right positions. A first guide rail seat (42) is fixed on the first fixing frame (41). A displacement sensor (43) is installed at one end of the first guide rail seat (42). A line measuring probe (44) is installed at the top of the displacement sensor (43). The other end of the first guide rail seat (42) is connected to the line measuring electromagnet (45).

[0020] To achieve better technical results, the motor winder (6) includes a second fixing frame (51), a second guide rail seat (52), a rail shaft (53), a spring clip (54), a motor (55), a slide rail (56), and a winding electromagnet (57). The motor winder (6) is fixed to the lower side of the platform (3) by the second fixing frame (51). The front end of the second fixing frame (51) is provided with two second guide rail seats (52) and slide rails (56).

[0021] The second guide rail seat (52) has a guide hole. One end of the rail shaft (53) passes through the guide hole and is connected to the winding electromagnet (57). The front end of the rail shaft (53) is connected to the spring clip (54). A motor (55) is provided on the rail shaft (53) between the second guide rail seat (52) and the spring clip (54). The motor (55) is connected to the second fixed frame (51) through the slide rail (56). The motor (55) can slide back and forth in the second fixed frame (51) along the slide rail (56) under the action of the winding electromagnet (57).

[0022] To achieve better technical results, the bottom thread clamp (7) includes a slide rail base (61), a slide rail plate (62), a thread clamping shear (63), a closed shearing plate (64), a toothed groove (65), a motor base (66), a servo motor (67), a gear (68), and an open shearing plate (69). The bottom thread clamp (7) is fixed to the lower side of the platform (3) via the slide rail base (61). The slide rail base (61) is provided with a sliding guide hole. One end of the slide rail plate (62) passes through the sliding guide hole and is fixedly connected to the thread clamping shear (63). A closed shearing plate (64) is provided between the wire clamping shear (63) and the rotary hook (4). A toothed groove (65) is provided on the slide rail plate (62) between the sliding guide hole and the wire clamping shear (63). A motor seat (66) is also fixed on the slide rail base (61). A servo motor (67) is installed on the motor seat (66). A gear (68) is fixed on the shaft of the servo motor (67). The gear (68) meshes with the toothed groove (65). An open shearing plate (69) is fixed at one end of the slide rail base (61) near the wire clamping shear (63).

[0023] The wire clamping shears (63) are composed of a first upper shear blade (71), a first lower shear blade (72), a first wire clamping spring plate (73), a first upper shear handle (74), and a first lower shear handle (75). The first lower shear handle (75) and the first lower shear blade (72) are fixedly connected; the first upper shear blade (71) and the first upper shear handle (74) are fixedly connected in an L-shape.

[0024] The first upper scissor blade (71) is located between the first wire clamping spring plate (73) and the first lower scissor handle (75), wherein the first upper scissor blade (71) and the first lower scissor handle (75) are arranged opposite to each other and movably connected, and the first wire clamping spring plate (73) and the first lower scissor handle (75) are fixedly connected.

[0025] The lower scissor handle (75) is fixed to the front end of the slide rail plate (62), and the upper scissor handle (74) is provided with an opening and closing stop (76) at its end.

[0026] In order to achieve better technical results, the bottom wire cutter (8) is set below the platform (3). The bottom wire cutter (8) includes a cutter base (81), a wire cutting electromagnet (82), a movable connecting rod (89), and a wire cutting clamp (83).

[0027] A wire-breaking electromagnet (82) is fixed on the base (81) of the wire breaker, and a movable connecting rod (89) is fixedly installed at the front end of the wire-breaking electromagnet (82).

[0028] The wire cutter (83) consists of a second upper scissor blade (84), a second lower scissor blade (85), a second wire clamping spring plate (86), a second upper scissor handle (87), and a second lower scissor handle (88). The tail end of the second lower scissor handle (88) is fixed to the side wall of the wire cutter base (81), and the front end of the second lower scissor handle (88) is fixedly connected to the second lower scissor blade (85). The second upper scissor handle (87) and the second upper scissor blade (84) are fixedly connected in an L-shape.

[0029] The second upper scissor blade (84) is located between the second clamping spring plate (86) and the second lower scissor blade (85), wherein the second upper scissor blade (84) and the second lower scissor blade (85) are arranged opposite to each other and movably connected, and the second clamping spring plate (86) and the second lower scissor blade (85) are fixedly connected.

[0030] The second upper scissor handle (87) is connected to the top of the movable link (89).

[0031] In order to achieve better technical results, a bottom wire clamp (9) is provided in front of the bottom wire cutter (8). The bottom wire clamp (9) includes a clamp base (91), an air splicer (92), a U-shaped clamp rod (93), a movable shaft (94), a bracket (95), a movable rod (96), a clamp electromagnet (97), a front clamp rod (98), and a rear clamping groove clamp coil (99).

[0032] An air splicer (92) is fixed on the base (91) of the wire splicer. The air splicer (92) is located below the wire break clamp (83). A bracket (95) is provided on the right side of the air splicer (92). The bracket (95) includes a base plate and two support arms. The support arms and the wire splicing electromagnet (97) are fixed on the base plate.

[0033] The wire pressing electromagnet (97) contains a telescopic shaft, one end of which is connected to a movable rod (96); both ends of the movable rod (96) are connected to a U-shaped wire pressing rod (93), and four wire pressing ports are provided at one end of the U-shaped wire pressing rod (93) near the bottom wire cutter (8); the other end of the U-shaped wire pressing rod (93) is connected to the support arm of the bracket (95) through the movable shaft (94);

[0034] The air splicer (92) is provided with a front wire fixing rod (98) and a rear pressure groove fixing coil (99), which are respectively arranged on both sides of the wire break clamp (83).

[0035] The rear pressure wire fixing groove (99) is used to fix the bottom wire. When the U-shaped pressure rod (93) is pressed down, the bottom wire can be pressed into the air splicer (92) along the four pressure holes of the U-shaped pressure rod (93). After the bottom wire is connected, the bottom wire reaches the right bottom of the rear pressure wire fixing groove (99) under its own elastic force when winding. In this way, the scissor blade of the bottom wire cutter (8) can cut the bottom wire.

[0036] In order to achieve better technical results, a bottom wire seat (102) is provided on the platform (3). A set of wire grooves (103) is provided at the front of the bottom wire seat (102). The bottom wire is placed on the bottom wire seat (102) in the form of a cylindrical wire. After the bottom wire enters the lower part of the platform (3) through the wire groove (103), it is introduced into the back pressure groove to fix the coil (99).

[0037] To achieve better technical results, a host control system (101) is also included, which controls the operation of displacement sensor (43), wire probe electromagnet (45), motor (55), winding electromagnet (57), servo motor (68), wire break electromagnet (82), air splicer (92), and wire pressing electromagnet (97).

[0038] In order to achieve better technical results, an activation switch (104) for the air splicer (92) is provided on the side wall of the air splicer (92) and below the U-shaped pressure bar (93).

[0039] This invention also provides a method for automatically attaching the bobbin thread using an automatic bobbin thread attachment device in a flat-seam sewing machine, the steps of which include:

[0040] (1) Bore thread threading stroke: The bore thread on the bore thread holder (102) enters the lower part of the sewing machine (1) table (3) along the thread groove (103). The main control system (101) is started, the thread breaking electromagnet (82) is started and the movable rod (89) is pulled back to open the blade of the thread breaking clipper (83). Then the bore thread is passed through the front thread fixing rod (98), then through the rear thread fixing groove (99), and finally the bore thread is placed into the blade of the thread breaking electromagnet (82). The main control system (101) is started again. After the thread breaking electromagnet (82) is de-energized, it extends forward under the action of the spring and passes through the movable connecting rod (89). When the second upper shear handle (87) is applied, the second upper shear blade (71) and the second lower shear blade (72) begin to close. Before the bottom thread is cut, the second lower shear blade (72) pulls the lower part of the bottom thread into the second clamping spring plate (73) between the second and lower shear blades (72). When the clamping shears (63) are fully closed and cut the bottom thread, the thread end of the bottom thread is clamped between the second clamping spring plate (73) and the second lower shear blade (72) under the elastic force of the second clamping spring plate (73). The second clamping spring plate (73) completes the clamping operation of the bottom thread under the pressure of its own elastic plate.

[0041] (2) Thread detection stroke: Each time the operator steps on the thread cutting pedal, the main control system (101) controls the detection electromagnet (45) to extend forward, causing the displacement sensor (43) and the thread probe (44) to move forward within the first guide rail (42). The thread probe (44) passes through the bottom of the rotary hook (4), then through the probe opening (36) on the shuttle case (25) and enters the bobbin (37). The thread probe (44) cannot extend further after contacting the bottom thread on the bobbin (37). The displacement sensor (43) contains a spring, and the detection electromagnet (45)... The force of the forward extension must be greater than the force of the spring inside the displacement sensor (43). Under the action of the forward extension force of the detection electromagnet (45), the line probe (44) retracts into the displacement sensor (43). The displacement sensor (43) calculates the retraction distance of the line probe (44) through potential sensing. The retraction distance of the line probe (44) is the thickness of the bottom thread on the hollow column of the bobbin (37). The preset conversion program in the host control system (101) displays the thickness of the bottom thread on the hollow column of the bobbin (37) detected by the line probe (44) as the line quantity of the bottom thread.

[0042] When the bottom line is detected to be at a relatively low value, the main control system (101) directly controls the bottom line clamp (7) to extend forward and clamp the bottom line after the operator steps the cutting pedal again, clamping the bottom line before the cutting device in the machine head cuts the bottom line;

[0043] When the preset full thread count is detected or the sewing machine operator changes machines and wants to start the next sewing operation, the motor (55) stops winding the thread, and then the winding electromagnet (57) stops extending forward. Under the action of the spring on the electromagnet (57) shaft, the guide shaft (53) in the guide rail seat (52) is pulled back, so that the motor (55) fixed on the guide shaft (53) is simultaneously pulled back in the slide rail (56); at the same time, the thread-breaking electromagnet (82) fixed on the thread breaker base (81) begins to break the thread. After the bottom thread is spliced, the bottom thread presser (9) is pulled back by the spring on the pressing electromagnet (97) shaft, and the bottom thread is pulled back by the tension. The rear groove wire holder (99) is pulled up and passes through the middle gap to the right top of the wire holder. The electromagnet (82) is activated and pulls open the scissor of the wire cutter (83) through the movable connecting rod (89). The bottom wire is pulled into the scissor of the wire cutter (83) under the elastic action of the rear groove wire holder coil (99) and the bottom wire itself. Then the electromagnet (82) stops working and pulls back the wire cutter (83) to cut the bottom wire under the action of the spring on the shaft of the electromagnet (82). At the same time as cutting the wire, the front bottom wire is pulled into the space between the upper scissor blade (84) and the second wire clamping spring plate (86). The bottom wire is clamped under the elastic force of the second wire clamping spring plate (86).

[0044] (3) Bottom thread clamping, winding and splicing stroke: When the thread quantity detector detects that the amount of thread on the bobbin (37) is too small, the servo motor (67) of the bottom thread clamp (7) starts, and the tooth groove (65) meshing with the gear (68) causes the slide plate (62) to extend forward in the slide plate seat (61) under the rotation of the gear (68). The thread clamping shear (63) at the front end of the slide plate (62) quickly extends forward to the bobbin opening (35). When the opening and closing stop (76) of the first upper shear handle (74) of the thread clamping shear (63) passes the closing shear plate (64), because the closing shear plate (64) is round The arc-shaped opening and closing stop (76) is squeezed by the closing shear plate (64) during the forward extension process. The first upper shear blade (71) and the first lower shear blade (72) begin to close. Before the bottom line is cut, the first lower shear blade (72) pulls the lower part of the bottom line into the first clamping spring plate (73) between the first lower shear blade (72). When the clamping shear (63) is fully closed and cuts the bottom line, the end of the bottom line is clamped between the first clamping spring plate (73) and the first lower shear blade (72) under the elastic force of the first clamping spring plate (73). When the wire clamping shear (63) is fully closed, the servo motor (67) starts to rotate in the opposite direction under the preset program. The front gear (68) acts on the tooth groove (65) to make the slide plate (62) retract in the slide seat (61). The wire clamping shear (63) at the front end of the slide plate (62) clamps the end of the bobbin (37) and retracts to the front end of the air splicer 92.

[0045] When the wire clamping shear (63) pulls back the bottom wire, the bottom wire clamp (91) located on the clamping base (91) starts to work under the action of the clamping electromagnet (97). The clamping electromagnet (97) causes the U-shaped clamping rod (93) fixed on the bracket (95) to start pressing down under the action of the movable shaft (94) through the movable rod (96). Under the action of the front clamping rod (98) and the rear clamping groove clamping coil (99), the four clamping holes on the U-shaped clamping rod (93) press the two crossed bottom wires into the splicing groove of the air splicer (92). When the U-shaped clamping rod (97) is pressed down to the lowest point, the start switch (104) on the air splicer (92) is pressed down through the connecting rod (105), and the air splicer (92) works and splices the bottom wires.

[0046] (4) Reciprocating cycle: During the operation of the sewing machine (1), steps (2)-(3) are repeated to prepare for the next stroke. When the bobbin thread in the rotary hook (4) is insufficient, the bobbin thread is automatically replenished.

[0047] This invention adds automatic bobbin thread joining, pressing, winding, and cutting functions without altering the existing sewing machine's functionality. After the operator completes a garment-making cycle and automatically cuts the thread, and needs to change fabric pieces or complete a custom garment, this technology automatically, under the control of the system host, uses electromagnets, motors, and solenoid valves to complete the automatic thread joining, pressing, winding, and cutting processes in a very short time. Furthermore, even if the bobbin thread is not fully wound, sewing can begin as soon as the operator steps on the sewing pedal, because the sewing machine system control host can synchronously control the motor to stop winding and quickly cut the bobbin thread before sewing begins, eliminating the need for the operator to stop and wait – it's fully automated! This overcomes the low efficiency and high cost of manual bobbin thread changing, making it suitable for a large portion of garment manufacturing needs and laying the foundation for future fully automated garment production. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the sewing machine structure according to an embodiment of the present invention;

[0049] Figure 2 This is a schematic diagram of the platform structure from below according to an embodiment of the present invention;

[0050] Figure 3 This is a rendering of the bottom thread clamp, bottom thread presser, and bottom thread cutter before the rotary hook, according to an embodiment of the present invention.

[0051] Figure 4 This is a rendering of the motor winding device before the rotary hook in an embodiment of the present invention;

[0052] Figure 5 This is a schematic diagram of the rotary shuttle structure according to an embodiment of the present invention;

[0053] Figure 6 This is a schematic diagram of the shuttle shell structure according to an embodiment of the present invention;

[0054] Figure 7 This is a schematic diagram of the bobbin structure according to an embodiment of the present invention;

[0055] Figure 8 This is a front view of the rotary hook core according to an embodiment of the present invention;

[0056] Figure 9 This is a right oblique view of the rotary hook core according to an embodiment of the present invention;

[0057] Figure 10 This is a schematic diagram of the bobbin mounting according to an embodiment of the present invention;

[0058] Figure 11 This is a schematic diagram of the shuttle housing installation according to an embodiment of the present invention;

[0059] Figure 12 This is a schematic diagram of the operation of the motor winding device according to an embodiment of the present invention;

[0060] Figure 13 This is a schematic diagram of the motor winding structure according to an embodiment of the present invention;

[0061] Figure 14 This is a schematic diagram of the bottom wire clamp waiting to work according to an embodiment of the present invention;

[0062] Figure 15 This is a schematic diagram illustrating the operation of the bottom wire clamp according to an embodiment of the present invention;

[0063] Figure 16 This is a schematic diagram of the wire clamping and cutting shearing method according to an embodiment of the present invention;

[0064] Figure 17 This is a schematic diagram of the wire clamp shear closing method according to an embodiment of the present invention;

[0065] Figure 18 This is a schematic diagram of the bottom wire disconnector structure according to an embodiment of the present invention;

[0066] Figure 19 This is a schematic diagram of the wire measurement probe structure according to an embodiment of the present invention;

[0067] Figure 20 This is a schematic diagram of the bottom thread clamp and air splicer structure according to an embodiment of the present invention;

[0068] Figure 21 This is a schematic diagram of the operation of the bottom thread clamp and air splicer in an embodiment of the present invention;

[0069] Figure 22 This is a schematic diagram of the coil structure after pressing the groove in an embodiment of the present invention.

[0070] Among them, 1-sewing machine, 2-machine head, 3-table, 4-rotary hook, 5-thread quantity detector, 6-motor winding device, 7-bottom thread clamp, 8-bottom thread breaker, 9-bottom thread presser, 101-main control system, 102-bottom thread holder, 103-thread groove, 104-start switch, 21-rotary hook core, 22-L-shaped bobbin case slot, 23-bobbin case concealed latch, 24-bobbin post, 25-bobbin case, 26-bobbin case plate. 27-Lock head, 31-Round hole, 32-Reversible bobbin skin, 33-Fixed thread hole, 34-Threading hole, 35-Bobbin case opening, 36-Probe opening, 37-Bobbin core, 38-Hollow column, 39-Clamping block, 41-Fixed frame, 42-Guide rail base, 43-Displacement sensor, 44-Line measurement probe, 45-Line detection electromagnet, 51-Second fixed frame, 52-Second guide rail base, 53-Rail shaft, 54-Spring clip, 55-Motor, 56- 57-Slide rail, 61-Slide rail base, 62-Slide rail plate, 63-Wire clamping shears, 64-Closed shear plate, 65-Groove, 66-Motor base, 67-Servo motor, 68-Gear, 69-Opening shear plate, 71-First upper shear blade, 72-First lower shear blade, 73-First wire clamping spring plate, 74-First upper shear handle, 75-First lower shear handle, 76-Opening and closing stop, 81-Wire cutter base, 82-Wire cutter... 83-Wire clamping shears, 84-Second upper shear blade, 85-Second lower shear blade, 86-Second clamping spring plate, 87-Second upper shear handle, 88-Second lower shear handle, 89-Modible connecting rod, 91-Wire clamping device base, 92-Air splicer, 93-U-shaped wire clamping rod, 94-Modible shaft, 95-Bracket, 96-Modible rod, 97-Wire clamping electromagnet, 98-Front wire fixing rod, 99-Rear clamping groove for fixing coil. Detailed Implementation

[0071] In the description of this invention, it should be understood that the terms "front end," "rear end," "upper end," "lower end," "front," "rear," "left," "right," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0072] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances. Therefore, although the invention has been described in detail through the above embodiments, the invention is not limited to the above embodiments. Many other equivalent embodiments can be included without departing from the inventive concept, and the scope of the invention is determined by the scope of the appended claims.

[0073] The best mode of carrying out the present invention will now be described with reference to the accompanying drawings.

[0074] Example 1

[0075] An automatic bobbin thread splicing device for a flat-seam sewing machine includes a sewing machine head (2), a table (3), a rotary hook (4), a thread quantity detector (5), a motor winding device (6), a bobbin thread clamp (7), a bobbin thread breaker (8), and a bobbin thread presser (9), characterized in that...

[0076] The sewing machine (1) has its head (2) fixed on the table (3), and a rotary hook (4) is fixed on the shaft of the head (2) located below the table (3).

[0077] The rotary hook (4) is provided with a line quantity detector (5) on its side, and a motor winding device (6) is provided in front of the rotary hook (4). The bottom thread clamping device (9), the bottom thread breaker (8), and the bottom thread clamping device (7) are provided in sequence in front of the rotary hook (4).

[0078] Example 2

[0079] Compared to the conventional rotary hook 4, shuttle case 25, and bobbin 37, improvements are needed to enable the probe 44 of the thread detector 5, the spring clip 54 of the motor winder 6, and the thread clamping shear 64 of the bottom thread clamp 7 to perform thread detection, winding, and clamping operations.

[0080] An automatic bobbin threading device for a flat-seam sewing machine includes a sewing machine head (2), a table (3), a rotary hook (4), a thread quantity detector (5), a motor winding device (6), a bobbin thread clamp (7), a bobbin thread breaker (8), and a bobbin thread presser (9).

[0081] The sewing machine (1) has its head (2) fixed on the table (3), and a rotary hook (4) is fixed on the shaft of the head (2) located below the table (3).

[0082] A bottom wire seat (102) is provided on the platform (3), and a set of wire grooves (103) is provided at the front of the bottom wire seat (102); the bottom wire is placed on the bottom wire seat (102) in the form of a bobbin, and after the bottom wire enters the lower part of the platform (3) through the wire grooves (103), it is introduced into the back pressure groove fixed coil (99);

[0083] The rotary shuttle (4) includes a rotary shuttle core (21), a shuttle shell (25), and a shuttle core (37).

[0084] The rotary shuttle core (21) has an L-shaped shuttle case slot (22) on each of its corresponding inner core walls. A shuttle case opening is provided at the bottom of its inner core wall, and a hidden shuttle case opening (23) is provided at the shuttle case opening. The rotary shuttle core (21) also has a shuttle core post (24) at its center. The shuttle core post (24) is 2-10mm long.

[0085] The shuttle shell (25) is a cylindrical body with one end open and the other end closed. Its end face is arc-shaped and has a shuttle shell opening (35). A circular hole (31) is also provided at the center of the end face of the shuttle shell (25). The side wall of the shuttle shell (25) is provided with a reverse-clockwise shuttle skin (32). A thread fixing hole (33) is provided in front of the reverse-clockwise shuttle skin (32). A thread threading hole (34) is provided diagonally above the thread fixing hole (33). The outlet of the thread threading hole (34) is located on the shuttle shell. At the center of the shuttle opening (35) of (25), a probe opening (36) is provided on the lower right side wall of the shuttle (25); a shuttle flap (26) and a lock head (27) are provided on the outer side of the closed end face of the shuttle (25). The lock head (27) is composed of a sliding plate and a spring. One end of the spring is fixed on the shuttle (25). One end of the sliding plate is connected to the spring, and the other end is inserted into the shuttle slot. The shuttle flap (26) is movably connected to the sliding plate through its bottom.

[0086] When the trigger is pulled, the part of the trigger that contacts the inside of the slide will move backward, causing the slide to move backward and the lock head to retract. When the rotary hook core (21) is put into the shuttle case (25) and the shuttle case trigger (26) is lowered, the slide extends forward under the action of the spring, and the lock head (27) is locked into the hidden slot (23) of the shuttle case.

[0087] The outer wall of the shuttle (25) is provided with two locking blocks (39);

[0088] Pull up the shuttle case trigger (26) of the shuttle case (25) to retract the lock head (27) into the shuttle case (25). Then, in the rotating shuttle core (21), press down the locking block (39) on the outer wall of the shuttle case (25) along the L-shaped shuttle case slot (22) and rotate it clockwise to fix the shuttle case (25) in the shuttle case (25).

[0089] In order to fix the shuttle shell (25), in this embodiment, two locking blocks (39) are designed on the shell wall of the shuttle shell (25), two L-shaped shuttle shell locking grooves (22) are designed on the left and right core walls of the rotary shuttle core (21), and a shuttle shell hidden locking groove (23) is designed below the shuttle shell locking groove of the rotary shuttle core (21). When the shuttle case trigger (26) of the shuttle case (25) is lifted, the lock head (27) retracts into the shuttle case (25). Then, the locking block (39) on the shell wall presses down along the L-shaped shuttle case slot (22) and rotates clockwise. Then, the shuttle case trigger (26) is released, and the lock head (27) rotates into the shuttle case hidden slot (23) through the shuttle case slot. The L-shaped shuttle case slot (22) can prevent the shuttle case (25) from moving up and down, while the shuttle case hidden slot (23) can prevent the shuttle case (25) from moving left and right. In this way, the shuttle case opening (25) is fixed in the rotary shuttle (4).

[0090] The bobbin (37) consists of two identical disc-shaped end faces and a hollow column (38). The two ends of the hollow column (38) pass through the center of the two end faces respectively, and fix the two end faces at their ends. The inner diameter of the hollow column (38) is 4-5 mm. As an optimization, the bobbin column (24) is 2-3 mm long.

[0091] The hollow column (38) of the bobbin (37) is fitted onto the bobbin column (24) and fixed inside the spindle (21);

[0092] The rotary shuttle core (21) is fixed inside the shuttle case (25);

[0093] A line detector (5) is provided on the side of the rotary shuttle (4).

[0094] The line measuring probe (5) includes a first fixed frame (41), a guide rail seat (42), a displacement sensor (43), and a line measuring probe (44).

[0095] The line measuring probe (5) is fixed to the lower side of the platform (3) by the first fixing frame (41). The first fixing frame (41) can be freely adjusted in the up, down, left and right positions. A first guide rail seat (42) is fixed on the first fixing frame (41). A displacement sensor (43) is installed at one end of the first guide rail seat (42). A line measuring probe (44) is installed at the top of the displacement sensor (43). The other end of the first guide rail seat (42) is connected to the line measuring electromagnet (45).

[0096] The function of the first guide rail seat (42) is to allow the line probe (44) to slide back and forth within the first guide rail seat (42). The line probe (44) extends forward under the action of the line probe electromagnet (45). In order to ensure that the line probe (44) can extend forward in a consistent position without deviation, this embodiment selects two first guide rail seats (42) to avoid the possibility that the probe position may deviate during the extension process after long-term use of a single first guide rail seat (42).

[0097] The rotary hook (4) is provided with a motor winding device (6) in front of it. The motor winding device (6) includes a second fixing frame (51), a second guide rail seat (52), a rail shaft (53), a spring clip (54), a motor (55), a slide rail (56), and a winding electromagnet (57). The motor winding device (6) is fixed to the lower side of the platform (3) by the second fixing frame (51). The front end of the second fixing frame (51) is provided with two second guide rail seats (52) and a slide rail (56).

[0098] The second guide rail seat (52) has a guide hole. One end of the rail shaft (53) passes through the guide hole and is connected to the winding electromagnet (57). The front end of the rail shaft (53) is connected to the spring clip (54). A motor (55) is provided on the rail shaft (53) between the second guide rail seat (52) and the spring clip (54). The motor (55) is connected to the second fixed frame (51) through the slide rail (56). The motor (55) can slide back and forth in the second fixed frame (51) along the slide rail (56) under the action of the winding electromagnet (57).

[0099] The rotary hook (4) is provided with a bottom thread clamp (9), a bottom thread breaker (8) and a bottom thread clamp (7) in sequence on the front side.

[0100] The bottom thread clamp (7) includes a slide rail base (61), a slide rail plate (62), a thread clamping shear (63), a closing shear plate (64), a toothed groove (65), a motor base (66), a servo motor (67), a gear (68), and an opening shear plate (69). The bottom thread clamp (7) is fixed to the lower side of the platform (3) via the slide rail base (61). The slide rail base (61) is provided with a sliding guide hole. One end of the slide rail plate (62) passes through the sliding guide hole and is fixedly connected to the thread clamping shear (63). The thread clamping shear (64)... 3) A closed shear plate (64) is provided between the rotary hook (4) and the slide rail plate (62) between the sliding guide hole and the wire clamping shear (63) is provided with a toothed groove (65). A motor seat (66) is also fixed on the slide rail base (61). A servo motor (67) is installed on the motor seat (66). A gear (68) is fixed on the shaft of the servo motor (67). The gear (68) meshes with the toothed groove (65). A shearing plate (69) is fixed at one end of the slide rail base (61) near the wire clamping shear (63).

[0101] The open shear plate (69) and the closed shear plate (64) have the same function and principle; they are iron plates with a certain angle. See Figure 16 and 17 The position of the baffle is changed by the movement of the fixed screw in the screw hole, thereby adjusting the opening and closing degree of the scissors;

[0102] The wire clamping shears (63) are composed of a first upper shear blade (71), a first lower shear blade (72), a first wire clamping spring plate (73), a first upper shear handle (74), and a first lower shear handle (75). The first lower shear handle (75) and the first lower shear blade (72) are fixedly connected; the first upper shear blade (71) and the first upper shear handle (74) are fixedly connected in an L-shape.

[0103] The first upper scissor blade (71) is located between the first wire clamping spring plate (73) and the first lower scissor handle (75), wherein the first upper scissor blade (71) and the first lower scissor handle (75) are arranged opposite to each other and movably connected, and the first wire clamping spring plate (73) and the first lower scissor handle (75) are fixedly connected.

[0104] The lower scissor handle (75) is fixed to the front end of the slide rail plate (62), and the upper scissor handle (74) is provided with an opening and closing stop (76) at its end.

[0105] The bottom wire cutter (8) is located below the platform (3). The bottom wire cutter (8) includes a cutter base (81), a wire-cutting electromagnet (82), a movable connecting rod (89), and a wire-cutting clamp (83).

[0106] A wire-breaking electromagnet (82) is fixed on the base (81) of the wire breaker, and a movable connecting rod (89) is fixedly installed at the front end of the wire-breaking electromagnet (82).

[0107] The wire cutter (83) consists of a second upper scissor blade (84), a second lower scissor blade (85), a second wire clamping spring plate (86), a second upper scissor handle (87), and a second lower scissor handle (88). The tail end of the second lower scissor handle (88) is fixed to the side wall of the wire cutter base (81), and the front end of the second lower scissor handle (88) is fixedly connected to the second lower scissor blade (85). The second upper scissor handle (87) and the second upper scissor blade (84) are fixedly connected in an L-shape.

[0108] The second upper scissor blade (84) is located between the second clamping spring plate (86) and the second lower scissor blade (85), wherein the second upper scissor blade (84) and the second lower scissor blade (85) are arranged opposite to each other and movably connected, and the second clamping spring plate (86) and the second lower scissor blade (85) are fixedly connected.

[0109] The second upper scissor handle (87) is connected to the top end of the movable connecting rod (89);

[0110] A bottom wire clamp (9) is provided in front of the bottom wire cutter (8). The bottom wire clamp (9) includes a clamp base (91), an air splicer (92), a U-shaped clamp rod (93), a movable shaft (94), a bracket (95), a movable rod (96), a clamp electromagnet (97), a front clamp rod (98), and a rear clamping groove clamp coil (99).

[0111] An air splicer (92) is fixed on the base (91) of the wire splicer. The air splicer (92) is located below the wire break clamp (83). A bracket (95) is provided on the right side of the air splicer (92). The bracket (95) includes a base plate and two support arms. The support arms and the wire splicing electromagnet (97) are fixed on the base plate.

[0112] The wire pressing electromagnet (97) contains a telescopic shaft, one end of which is connected to a movable rod (96); both ends of the movable rod (96) are connected to a U-shaped wire pressing rod (93), and four wire pressing ports are provided at one end of the U-shaped wire pressing rod (93) near the bottom wire cutter (8); the other end of the U-shaped wire pressing rod (93) is connected to the support arm of the bracket (95) through the movable shaft (94);

[0113] The air splicer (92) is provided with a front wire fixing rod (98) and a rear pressure groove fixing coil (99), which are respectively arranged on both sides of the wire break clamp (83).

[0114] The rear pressure wire fixing groove (99) is used to fix the bottom wire. When the U-shaped pressure rod (93) is pressed down, the bottom wire can be pressed into the air splicer (92) along the four pressure holes of the U-shaped pressure rod (93). After the bottom wire is connected, the bottom wire reaches the right bottom of the rear pressure wire fixing groove (99) under its own elastic force when winding. In this way, the scissor blade of the bottom wire cutter (8) can cut the bottom wire.

[0115] To achieve better technical results, a host control system (101) is also included, which controls the operation of displacement sensor (43), wire probe electromagnet (45), motor (55), winding electromagnet (57), servo motor (68), wire break electromagnet (82), air splicer (92), and wire pressing electromagnet (97).

[0116] An activation switch (104) for the air splicer (92) is provided on the side wall of the air splicer (92) and below the U-shaped wire clamp (93).

[0117] The four pressing holes on the U-shaped pressing rod (93) press the two crossed bottom wires into the splicing groove of the air splicer (92). When the U-shaped pressing rod (93) presses the bottom wires down to the lowest point, the U-shaped pressing rod (93) will simultaneously press down the start switch (104) of the air splicer (92). The start switch (104) controls the start of the air splicer (92), and then the air splicer (92) works and splices the bottom wires.

[0118] Example 3

[0119] A method for automatically attaching bobbin thread to a flat-seam sewing machine using an automatic bobbin thread attachment device, comprising the following steps:

[0120] (1) Bore thread threading stroke: The bore thread on the bore thread holder (102) enters the lower part of the sewing machine (1) table (3) along the thread groove (103). The main control system (101) is started, the thread breaking electromagnet (82) is started and the movable rod (89) is pulled back to open the blade of the thread breaking clipper (83). Then the bore thread is passed through the front thread fixing rod (98), then through the rear thread fixing groove (99), and finally the bore thread is placed into the blade of the thread breaking electromagnet (82). The main control system (101) is started again. After the thread breaking electromagnet (82) is de-energized, it extends forward under the action of the spring and passes through the movable connecting rod (89). When the second upper shear handle (87) is applied, the second upper shear blade (71) and the second lower shear blade (72) begin to close. Before the bottom thread is cut, the second lower shear blade (72) pulls the lower part of the bottom thread into the second clamping spring plate (73) between the second and lower shear blades (72). When the clamping shears (63) are fully closed and cut the bottom thread, the thread end of the bottom thread is clamped between the second clamping spring plate (73) and the second lower shear blade (72) under the elastic force of the second clamping spring plate (73). The second clamping spring plate (73) completes the clamping operation of the bottom thread under the pressure of its own elastic plate.

[0121] (2) Thread detection stroke: Each time the operator steps on the thread cutting pedal, the main control system (101) controls the detection electromagnet (45) to extend forward, causing the displacement sensor (43) and the thread probe (44) to move forward within the first guide rail (42). The thread probe (44) passes through the bottom of the rotary hook (4), then through the probe opening (36) on the shuttle case (25) and enters the bobbin (37). The thread probe (44) cannot extend further after contacting the bottom thread on the bobbin (37). The displacement sensor (43) contains a spring, and the detection electromagnet (45)... The force of the forward extension must be greater than the force of the spring inside the displacement sensor (43). Under the action of the forward extension force of the detection electromagnet (45), the line probe (44) retracts into the displacement sensor (43). The displacement sensor (43) calculates the retraction distance of the line probe (44) through potential sensing. The retraction distance of the line probe (44) is the thickness of the bottom thread on the hollow column of the bobbin (37). The preset conversion program in the host control system (101) displays the thickness of the bottom thread on the hollow column of the bobbin (37) detected by the line probe (44) as the line quantity of the bottom thread.

[0122] When the bottom line is detected to be at a relatively low value, the main control system (101) directly controls the bottom line clamp (7) to extend forward and clamp the bottom line after the operator steps the cutting pedal again, clamping the bottom line before the cutting device in the machine head cuts the bottom line;

[0123] When the preset full thread count is detected or the sewing machine operator changes machines and wants to start the next sewing operation, the motor (55) stops winding the thread, and then the winding electromagnet (57) stops extending forward. Under the action of the spring on the electromagnet (57) shaft, the guide shaft (53) in the guide rail seat (52) is pulled back, so that the motor (55) fixed on the guide shaft (53) is simultaneously pulled back in the slide rail (56); at the same time, the thread-breaking electromagnet (82) fixed on the thread breaker base (81) begins to break the thread. After the bottom thread is spliced, the bottom thread presser (9) is pulled back by the spring on the pressing electromagnet (97) shaft, and the bottom thread is pulled back by the tension. The rear groove wire holder (99) is pulled up and passes through the middle gap to the right top of the wire holder. The electromagnet (82) is activated and pulls open the scissor of the wire cutter (83) through the movable connecting rod (89). The bottom wire is pulled into the scissor of the wire cutter (83) under the elastic action of the rear groove wire holder coil (99) and the bottom wire itself. Then the electromagnet (82) stops working and pulls back the wire cutter (83) to cut the bottom wire under the action of the spring on the shaft of the electromagnet (82). At the same time as cutting the wire, the front bottom wire is pulled into the space between the upper scissor blade (84) and the second wire clamping spring plate (86). The bottom wire is clamped under the elastic force of the second wire clamping spring plate (86).

[0124] (3) Bottom thread clamping, winding and splicing stroke: When the thread quantity detector detects that the amount of thread on the bobbin (37) is too small, the servo motor (67) of the bottom thread clamp (7) starts, and the tooth groove (65) meshing with the gear (68) causes the slide plate (62) to extend forward in the slide plate seat (61) under the rotation of the gear (68). The thread clamping shear (63) at the front end of the slide plate (62) quickly extends forward to the bobbin opening (35). When the opening and closing stop (76) of the first upper shear handle (74) of the thread clamping shear (63) passes the closing shear plate (64), because the closing shear plate (64) is round The arc-shaped opening and closing stop (76) is squeezed by the closing shear plate (64) during the forward extension process. The first upper shear blade (71) and the first lower shear blade (72) begin to close. Before the bottom line is cut, the first lower shear blade (72) pulls the lower part of the bottom line into the first clamping spring plate (73) between the first lower shear blade (72). When the clamping shear (63) is fully closed and cuts the bottom line, the end of the bottom line is clamped between the first clamping spring plate (73) and the first lower shear blade (72) under the elastic force of the first clamping spring plate (73). When the wire clamping shear (63) is fully closed, the servo motor (67) starts to rotate in the opposite direction under the preset program. The front gear (68) acts on the tooth groove (65) to make the slide plate (62) retract in the slide seat (61). The wire clamping shear (63) at the front end of the slide plate (62) clamps the end of the bobbin (37) and retracts to the front end of the air splicer 92.

[0125] When the wire clamping shear (63) pulls back the bottom wire, the bottom wire clamp (91) located on the clamping base (91) starts to work under the action of the clamping electromagnet (97). The clamping electromagnet (97) causes the U-shaped clamping rod (93) fixed on the bracket (95) to start pressing down under the action of the movable shaft (94) through the movable rod (96). Under the action of the front clamping rod (98) and the rear clamping groove clamping coil (99), the four clamping holes on the U-shaped clamping rod (93) press the two crossed bottom wires into the splicing groove of the air splicer (92). When the U-shaped clamping rod (97) is pressed down to the lowest point, the start switch (104) on the air splicer (92) is pressed down through the connecting rod (105), and the air splicer (92) works and splices the bottom wires.

[0126] (4) Reciprocating cycle: During the operation of the sewing machine (1), steps (2)-(3) are repeated to prepare for the next stroke. When the bobbin thread in the rotary hook (4) is insufficient, the bobbin thread is automatically replenished.

[0127] Modern flatbed sewing machines are primarily computerized flatbed sewing machines. These machines are typically powered by servo motors. The advantage of servo motors is that they allow the needle and hook to stop at a fixed position after the thread trimmer pedal is pressed. This allows the automatic thread trimmer to cut the appropriate length of top and bottom thread, and also allows the needle to stop at its highest point, so the operator can easily remove the workpiece after lifting the presser foot. Therefore, after sewing one piece, the hook 4 on a computerized flatbed sewing machine will always stop at a fixed position, as shown in the instruction manual. Figure 1 The position where the rotary hook 4 stops is the position it stops at after the thread-cutting pedal is pressed. There is a space gap on the lower right side of the rotary hook 4. In order for the thread quantity detector 5 to enter the shuttle case to detect the amount of thread, a probe port 36 is opened at the bottom of the shuttle case 25, as shown in the instruction manual. Figure 3 As shown. The conventional shuttle case 25 is fixed inside the rotary hook 4 by the shuttle case trigger engaging the slot of the rotary hook core 24 to prevent vertical movement, and by the locking head on the shuttle case trigger engaging the slot of the rotary hook core 21 to prevent horizontal movement. Thus, the shuttle case 25 is fixed to the rotary hook 4 and will not move. (See attached instruction manual.) Figure 4 As shown, in order to allow the spring clip 54 of the motor winder 6 to extend into the bobbin 37 for winding under the action of the winding electromagnet 57, the present invention cuts the length of the rotary bobbin post 24 to only a few millimeters and opens a round hole 31 in the center of the bobbin case 25. In this way, the spring clip 54 can enter the bobbin 37 through this round hole 31 and be locked into the column tube in the center of the bobbin 37 by the spring elasticity of the spring clip 54. After cutting off the length of the rotary bobbin post 24, the bobbin case 25 cannot be fixed in the rotary hook 4. In order to fix the bobbin case 25, the present invention designs two locking blocks 39 on the shell wall of the bobbin case 25, two L-shaped bobbin case locking grooves 22 on the left and right core walls of the rotary bobbin 21, and a bobbin case hidden locking groove 23 below the bobbin case locking groove of the rotary bobbin 21. When the bobbin case 25 is pulled up, the locking head retracts into the bobbin case. Then, the locking block 39 on the case wall presses down along the L-shaped bobbin case groove 22 and rotates clockwise. Releasing the bobbin case trigger allows the locking head to rotate through the bobbin case latch and into the bobbin case hidden latch 23. The L-shaped bobbin case groove 22 prevents the bobbin case 25 from moving up and down, while the hidden latch 23 prevents it from moving left and right. Thus, the bobbin case 25 is fixed inside the rotary hook 4. The rotary hook core column 24, cut to about one centimeter in length, and the hollow column 38, with a center diameter of four to five millimeters on one end face of the bobbin 37, serve to fix the bobbin 37, allowing it to run smoothly during high-speed rotation. (See attached instruction manual.) Figure 2As shown, in order to allow the thread clamping cutter 63 of the thread clamping device 7 to have a position to clamp and cut the thread, the present invention has a thread fixing hole 33 designed in front of the reverse and forward bobbin skin 32 of the bobbin case 25. The thread fixing hole 33 prevents the thread from sliding out of the reverse and forward bobbin skin 32 during sliding. A thread threading hole 34 is designed in the upper middle part of the thread fixing hole 33. The thread outlet of the thread threading hole 34 is located at the center line of the bobbin case opening 35 of the bobbin case 25. This is because the thread must pass through the needle plate eye when it is pulled into the fabric of the operating component by the top thread, and the thread is positioned after passing through the thread outlet of the thread threading hole 33. Directly below the needle plate eye, the thread cutter 63, under the action of the servo motor 67, extends forward into the bobbin case opening 35 to cut and retract the bobbin thread. During sewing machine operation, the machine does not work continuously. After each workpiece is completed and the thread cutting pedal is pressed, the operator must switch to another workpiece. Simultaneously, each time the thread cutting pedal is pressed, the thread quantity detector 5 detects how much bobbin thread remains in the bobbin 37. After the thread cutting device cuts the top thread and the bobbin thread, as per the instruction manual... Figure 8 As shown, the main control system 101 controls the thread quantity detector 5 to work, the thread detection electromagnet 45 to work and push the displacement sensor 43 forward. The displacement sensor 43 is located on the two guide rail seats 42 of the fixed frame 41. When the thread quantity probe 44 on the displacement sensor 43 is pushed forward, it enters the bobbin 37 through the probe port 36 under the bobbin case 25. Under the pressure of the remaining thread in the bobbin 37, the displacement sensor 43 calculates the displacement distance of the thread quantity probe 44. In this way, the main control system 101 knows how much thread is left in the bobbin 37 through electrical signals and displays the information on the display screen of the machine head 2. When the thread quantity on the bobbin 37 is detected to be lower than a certain preset value, when the sewing machine operator steps on the thread cutting pedal again to sew the next operation, the thread cutting device of the sewing machine starts and the bobbin thread clamp 7 starts at the same time, as shown in the attached instruction manual. Figure 6 As shown, the bottom thread clamp 7 is fixed to the bottom plate 3 by the slide rail base 61. The servo motor 67 is started, and through the front gear 68, it acts on the tooth groove 65 to make the slide rail plate 62 extend forward inside the slide rail base 61. The thread clamping cutter 63 at the front end of the slide rail plate 62 quickly extends forward to the shuttle opening 35, as shown in the instruction manual. Figure 7As shown, when the opening / closing stop 76 of the scissor handle 74 on the wire clamping shear 63 passes the closing shear plate 64, because the closing shear plate 64 is arc-shaped, the opening / closing stop 76 is squeezed by the closing shear plate 64 during its forward extension. The upper scissor blade 71 and the lower scissor blade 72 begin to close. Before the bottom thread is cut, the lower scissor blade 72 pulls the lower part of the bottom thread into the first wire clamping spring plate 73 between the lower scissor blade 72. When the wire clamping shear 63 is fully closed and cuts the bottom thread, the thread end of the bottom thread is clamped between the first wire clamping spring plate 73 and the lower scissor blade 72 under the elastic force of the first wire clamping spring plate 73. After the wire clamping shear 63 is fully closed, the servo motor 67 starts to rotate in the reverse direction under the preset program. The front gear 68 acts on the tooth groove 65 to retract the slide rail plate 62 in the slide rail seat 61. The wire clamping shear 63 at the front end of the slide rail plate 62 clamps the thread end of the bobbin 37 and retracts to the front end of the air splicer 92. (See attached instruction manual) Figure 9 As shown, when the wire clamp 63 pulls back the bottom thread, the bottom thread clamp 9 located on the clamp base 91 starts working under the action of the clamping electromagnet 97. The clamping electromagnet 97, through the movable rod 96, causes the U-shaped clamping rod 93 fixed on the bracket 95 to start pressing down under the action of the movable shaft 94. Under the action of the front clamping rod 98 and the rear clamping groove clamping coil 99, the four clamping holes on the U-shaped clamping rod 93 press the two crossed bottom threads into the splicing groove of the air splicer 92. When the U-shaped clamping rod 97 is pressed down to its lowest point, the start switch 104 on the air splicer 92 is pressed down through the connecting rod 105, and the air splicer 92 works and splices the bottom thread. At the same time as the bottom thread clamp 7 and the bottom thread clamp 9 are working, the motor winding machine 6 has started working, as shown in the attached instruction manual. Figure 5 As shown, the winding electromagnet 57 is started and pushed forward. The motor winding device 6 is fixed to the bottom of the platform 3 by the fixing bracket 51. The winding electromagnet 57 pushes the rail shaft 53 in the guide rail seat 52 forward, so that the motor 55 fixed on the rail shaft 53 is pushed forward in the slide rail 56 at the same time. The spring clip 54 at the front end of the rail shaft is pushed into the central circular hole 31 of the bobbin 37 and is locked in the central column tube of the bobbin 37 by the spring of the spring clip 54. After the air splicer 92 splices the bobbin thread, the motor 55 starts and begins winding. The bobbin thread on the bobbin thread holder 102 is wound into the bobbin 37 through the thread groove 103. While the motor 55 is winding, the thread quantity detector 5 also detects the amount of thread in the bobbin 37 every few seconds. When the preset full thread quantity is detected, or when the sewing machine operator changes machines and wants to start the next sewing operation, the motor 55 stops winding. Then, the winding electromagnet 57 stops extending forward, and under the action of the spring on the electromagnet 57 shaft, it pulls back the guide shaft 53 in the guide rail holder 52, causing the motor 55, fixed to the guide shaft 53, to be simultaneously pulled back within the slide rail 56. At the same time, the thread-breaking electromagnet 82 fixed on the thread breaker base 81 begins to break the thread, as per the instruction manual. Figure 9As shown, after the bottom wire is spliced, the bottom wire clamping device 9 pulls back the U-shaped clamping rod 93 under the action of the spring on the clamping electromagnet 97 shaft. Under the action of the tension, the bottom wire is pulled up by the rear clamping groove retainer 99 and passes through the middle gap to the right top of the retainer. The electromagnet 82 is activated and pulls open the scissor blades of the wire break clamping shear 83 through the movable connecting rod 89. The bottom wire is pulled into the scissor blades of the wire break clamping shear 83 under the elastic action of the rear clamping groove retaining coil 99 and the bottom wire itself. Then the electromagnet 82 stops working and pulls back the wire break clamping shear 83 under the action of the spring on the shaft of the electromagnet 82. As the thread is cut, the front thread is pulled between the upper shear blade 84 and the second clamping spring plate 86. The thread is clamped by the elastic force of the second clamping spring plate 86. Finally, the servo motor 67 continues to rotate in the opposite direction under the preset program. The front gear 68 acts on the tooth groove 65 to make the slide rail plate 62 continue to retract in the slide rail seat 61. At the same time, the clamping shear 63 at the front of the slide rail plate 62 retracts. During the retraction process, the opening and closing stop 76 on the clamping shear 63 is squeezed by the arc-shaped opening shear plate 69. The upper shear blade 71 and the lower shear blade 72 open to prepare for the next stroke.

[0128] The fixed position mentioned in this embodiment refers to the rotary hook notch stopping at a relatively fixed angle. The notch refers to the half-empty side of the rotary hook without the shuttle wall. The rotary hook rotates during operation. Before the price of servo motors decreased, stepper motors required a very complex system to stop at a fixed position. Stopping at a fixed position has two advantages. First, when the needle is sewing, it pierces the fabric from top to bottom. If the stopping position is random, the needle will stop inside or slightly on the fabric. In this case, you cannot take out the sewn fabric. You need to manually crank the machine head to make it rotate so that the needle stops at the highest position. Second, the length of the thread cut cannot be determined. If the top thread is too short, the needle will fly out during the next sewing.

[0129] With the widespread use of servo motors, the machine head can stop at a fixed position when the needle is at its highest point, and the position of the rotary hook and the needle are in the same position! Therefore, after the rotary hook stops rotating, the space gap will stop at a fixed position.

[0130] The rotary shuttle consists of a main body and a rotary shuttle core. The rotary shuttle core can rotate inside the shuttle, while the shuttle case cannot rotate. The shuttle itself must rotate, so to prevent the rotary shuttle core from rotating, there is a locking slot at the top of the rotary shuttle core. There is a positioning hook here. The bottom hook is fixed to the machine table and will not move. Therefore, the bottom hook locks the rotary shuttle core so that its position relative to the machine table will not move when the shuttle rotates at high speed.

[0131] The bobbin case has bobbin skin on its side wall. The reason it is on the side is because the bobbin is laid flat and the thread can only come out from the side. So the bobbin skin is on the side wall. In order to put the bobbin case into the spindle and at the same time allow the bobbin to hold more bobbin thread, because the more bobbin thread is loaded, the fewer times it needs to be replaced. Therefore, the spindle is not a complete cylindrical shape, but has a large notch at the bottom.

[0132] The positions of the spindle core and the spindle case are fixed by the positioning hook and will not change much. The line detector is also fixed, so it can enter through the notch to detect how much line is inside the spindle core.

[0133] However, the position of the rotary shuttle is not fixed; it must rotate continuously, only stopping when the machine is stopped. This is because its structure has a gap on one side and a shuttle wall on the other, which cannot be moved or modified. The design of the rotary shuttle has undergone hundreds of years of development, and its size and position cannot be easily changed. Firstly, if the rotary shuttle cannot stop in a fixed position, the probe may not be able to enter the shuttle case; secondly, the rotary shuttle needs to be rotated to adjust its position, but the range of adjustment is not large.

[0134] The probe opening selected in this invention was chosen through multiple observations. Although the bobbin case and the rotary hook core can be opened at any position, the upper part has a thread-cutting device and cannot be moved. The bobbin skin cannot be moved either; it can only be opened at the lower right corner. The rotary hook can only be opened at the notch in the part without the rotary hook wall, and this notch is located at the lower right corner when the needle stops.

[0135] This invention uses a main control system to control all solenoid valves, motors, and sensors, allowing a work cycle to be completed in a very short time. Even if the operator wants to start sewing at any time while the bobbin is being wound, they only need to press the start pedal. During the time between the sewing machine rotating and hooking the first bobbin thread but before hooking the second, the main control system first stops the winding motor, then retracts the winding motor via the winding electromagnet. At the same time as the winding motor retracts, the thread-cutting electromagnet is activated to cut the bobbin thread. Therefore, even if the bobbin thread is not fully wound around the bobbin case, the operator can start sewing at any time without stopping the machine. Moreover, the amount of bobbin thread to be wound and the time interval can also be set by the main control system. Therefore, regardless of the time it takes for the sewing machine operator to change a piece of fabric, the main control system, through program settings, can automatically complete the bobbin thread connection, automatic pressing, automatic winding, and automatic cutting processes when the operator steps down to sew the next piece. For special operating parts requiring very short replacement times, the manual thread change button on the display screen can be pressed, and the process can be completed shortly. Furthermore, this invention retains the conventional manual winding device on the sewing machine table, so the bobbin thread can also be changed manually. This invention is not limited to single-piece flatbed sewing machines but is applicable to all sewing equipment based on the flatbed sewing principle, including multi-piece combination machines and specialized machines modified from the flatbed sewing principle, such as embroidery machines, double-needle flatbed sewing machines, and high-leg flatbed sewing machines. The air splicer and thread cutter used in this invention are common sewing machine components, while the solenoid valve and electromagnet are also commonly used industrial equipment; therefore, the components in this invention are all very robust and durable.

[0136] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Although embodiments of the invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is limited by the claims and their equivalents.

Claims

1. An automatic bobbin thread joining device for a flat-seam sewing machine, comprising a sewing machine head (2), a table (3), a rotary hook (4), a thread quantity detector (5), a motor winding device (6), a bobbin thread clamp (7), a bobbin thread breaker (8), and a bobbin thread presser (9) of a sewing machine (1), wherein the sewing machine head (2) is fixed on the table (3), and a rotary hook (4) is fixed on a shaft located below the table (3) of the sewing machine head (2); a thread quantity detector (5) is provided on the side of the rotary hook (4), a motor winding device (6) is provided in front of the rotary hook (4), and a bobbin thread presser (9), a bobbin thread breaker (8), and a bobbin thread clamp (7) are sequentially provided on the side and front of the rotary hook (4), characterized in that, The rotary shuttle (4) includes a rotary shuttle core (21), a shuttle shell (25), and a shuttle core (37). The rotary shuttle core (21) has an L-shaped shuttle case slot (22) on each of its corresponding inner core walls. A shuttle case opening is provided at the bottom of its inner core wall, and a hidden shuttle case opening (23) is provided at the shuttle case opening. The rotary shuttle core (21) also has a shuttle core post (24) at its center. The shuttle shell (25) is a cylindrical body with one end open and the other end closed. Its end face is arc-shaped and has a shuttle shell opening (35). A circular hole (31) is also provided at the center of the end face of the shuttle shell (25). The side wall of the shuttle shell (25) is provided with a reverse-clockwise shuttle skin (32). A thread fixing hole (33) is provided in front of the reverse-clockwise shuttle skin (32). A thread threading hole (34) is provided diagonally above the thread fixing hole (33). The outlet of the thread threading hole (34) is located on the shuttle shell. At the center of the shuttle opening (35) of (25), a probe opening (36) is provided on the lower right side wall of the shuttle (25); a shuttle flap (26) and a lock head (27) are provided on the outer side of the closed end face of the shuttle (25). The lock head (27) is composed of a sliding plate and a spring. One end of the spring is fixed on the shuttle (25). One end of the sliding plate is connected to the spring, and the other end is inserted into the shuttle slot. The shuttle flap (26) is movably connected to the sliding plate through its bottom. The outer wall of the shuttle (25) is provided with two locking blocks (39); Pulling up the shuttle case trigger (26) of the shuttle case (25) causes the lock head (27) to retract into the shuttle case (25). The spindle core (21) presses down the locking block (39) on the outer wall of the shuttle case (25) along the L-shaped shuttle case slot (22) and rotates clockwise. Then, the shuttle case trigger (26) is lowered, and the lock head (27) extends forward under the action of the spring and is locked into the hidden slot (23) of the shuttle case, thus fixing the spindle core (21) inside the shuttle case (25). The bobbin (37) consists of two identical disc-shaped end faces and a hollow column (38). The two ends of the hollow column (38) pass through the center of the two disc-shaped end faces respectively, and fix the two disc-shaped end faces at its two ends. The hollow column (38) of the bobbin (37) is fitted onto the bobbin column (24) and fixed inside the spindle (21); The rotary shuttle core (21) is fixed inside the shuttle case (25); The motor winding device (6) includes a second fixing frame (51), a second guide rail seat (52), a rail shaft (53), a spring clip (54), a motor (55), a slide rail (56), and a winding electromagnet (57). The motor winding device (6) is fixed to the lower side of the platform (3) by the second fixing frame (51). The front end of the second fixing frame (51) is provided with two second guide rail seats (52) and slide rails (56). The second guide rail seat (52) has a guide hole. One end of the rail shaft (53) passes through the guide hole and is connected to the winding electromagnet (57). The front end of the rail shaft (53) is connected to the spring clip (54). A motor (55) is provided on the rail shaft (53) between the second guide rail seat (52) and the spring clip (54). The motor (55) is connected to the second fixed frame (51) through the slide rail (56). Under the action of the winding electromagnet (57), the motor (55) slides back and forth along the slide rail (56) in the second fixed frame (51). The bottom wire cutter (8) is located below the platform (3). The bottom wire cutter (8) includes a cutter base (81), a wire-cutting electromagnet (82), a movable connecting rod (89), and a wire-cutting clamp (83). A wire-breaking electromagnet (82) is fixed on the base (81) of the wire breaker, and a movable connecting rod (89) is fixedly installed at the front end of the wire-breaking electromagnet (82). The wire cutter (83) consists of a second upper scissor blade (84), a second lower scissor blade (85), a second wire clamping spring plate (86), a second upper scissor handle (87), and a second lower scissor handle (88). The tail end of the second lower scissor handle (88) is fixed to the side wall of the wire cutter base (81), and the front end of the second lower scissor handle (88) is fixedly connected to the second lower scissor blade (85). The second upper scissor handle (87) and the second upper scissor blade (84) are fixedly connected in an L-shape. The second upper scissor blade (84) is located between the second clamping spring plate (86) and the second lower scissor blade (85), wherein the second upper scissor blade (84) and the second lower scissor blade (85) are arranged opposite to each other and movably connected, and the second clamping spring plate (86) and the second lower scissor blade (85) are fixedly connected. The second upper scissor handle (87) is connected to the top end of the movable connecting rod (89); A bottom wire clamp (9) is provided in front of the bottom wire cutter (8). The bottom wire clamp (9) includes a clamp base (91), an air splicer (92), a U-shaped clamp rod (93), a movable shaft (94), a bracket (95), a movable rod (96), a clamp electromagnet (97), a front clamp rod (98), and a rear clamping groove clamp coil (99). An air splicer (92) is fixed on the base (91) of the wire splicer. The air splicer (92) is located below the wire break clamp (83). A bracket (95) is provided on the right side of the air splicer (92). The bracket (95) includes a base plate and two support arms. The support arms and the wire splicing electromagnet (97) are fixed on the base plate. The wire pressing electromagnet (97) contains a telescopic shaft, one end of which is connected to a movable rod (96); both ends of the movable rod (96) are connected to a U-shaped wire pressing rod (93), and four wire pressing ports are provided at one end of the U-shaped wire pressing rod (93) near the bottom wire cutter (8); the other end of the U-shaped wire pressing rod (93) is connected to the support arm of the bracket (95) through the movable shaft (94); The air splicer (92) is provided with a front wire fixing rod (98) and a rear pressure groove fixing coil (99), which are respectively arranged on both sides of the wire break clamp (83).

2. The automatic thread-joining device for a flat-seam sewing machine as described in claim 1, characterized in that, The linear detector (5) includes a first fixed frame (41), a first guide rail seat (42), a displacement sensor (43), and a linear probe (44). The line detector (5) is fixed to the lower side of the platform (3) by the first fixing frame (41). The first fixing frame (41) can be freely adjusted in position up, down, left and right. A first guide rail seat (42) is fixed on the first fixing frame (41). A displacement sensor (43) is installed at one end of the first guide rail seat (42). A line probe (44) is installed at the top of the displacement sensor (43). The other end of the first guide rail seat (42) is connected to the line probe electromagnet (45).

3. The automatic thread-joining device for a flat-seam sewing machine as described in claim 1, characterized in that, The bottom thread clamp (7) includes a slide rail base (61), a slide rail plate (62), a thread clamping shear (63), a closing shear plate (64), a toothed groove (65), a motor base (66), a servo motor (67), a gear (68), and an opening shear plate (69). The bottom thread clamp (7) is fixed to the lower side of the platform (3) via the slide rail base (61). The slide rail base (61) is provided with a sliding guide hole. One end of the slide rail plate (62) passes through the sliding guide hole and is fixedly connected to the thread clamping shear (63). The thread clamping shear (64)... 3) A closed shear plate (64) is provided between the rotary hook (4) and the slide rail plate (62) between the sliding guide hole and the wire clamping shear (63) is provided with a toothed groove (65). A motor seat (66) is also fixed on the slide rail base (61). A servo motor (67) is installed on the motor seat (66). A gear (68) is fixed on the shaft of the servo motor (67). The gear (68) meshes with the toothed groove (65). A shearing plate (69) is fixed at one end of the slide rail base (61) near the wire clamping shear (63). The wire clamping shears (63) are composed of a first upper shear blade (71), a first lower shear blade (72), a first wire clamping spring plate (73), a first upper shear handle (74), and a first lower shear handle (75). The first lower shear handle (75) and the first lower shear blade (72) are fixedly connected; the first upper shear blade (71) and the first upper shear handle (74) are fixedly connected in an L-shape. The first upper scissor blade (71) is located between the first wire clamping spring plate (73) and the first lower scissor handle (75), wherein the first upper scissor blade (71) and the first lower scissor handle (75) are arranged opposite to each other and movably connected, and the first wire clamping spring plate (73) and the first lower scissor handle (75) are fixedly connected. The first lower scissor handle (75) is fixed to the front end of the slide rail plate (62), and the end of the first upper scissor handle (74) is provided with an opening and closing stop (76).

4. The automatic thread-joining device for a flat-seam sewing machine as described in claim 1, characterized in that, A bottom wire seat (102) is provided on the platform (3). A set of wire grooves (103) is provided at the front of the bottom wire seat (102). The bottom wire is placed on the bottom wire seat (102) in the form of a cylindrical wire. After the bottom wire enters the lower part of the platform (3) through the wire grooves (103), it is introduced into the back pressure groove to fix the coil (99).

5. The automatic thread-joining device for a flat-seam sewing machine as described in claim 1, characterized in that, It also includes a host control system (101), which controls the operation of displacement sensor (43), wire probe electromagnet (45), motor (55), winding electromagnet (57), servo motor (67), wire break electromagnet (82), air splicer (92), and wire pressing electromagnet (97).

6. A method for automatically joining bobbin threads, employing the automatic bobbin thread joining device of a flat-seam sewing machine as described in any one of claims 1-5, comprising the following steps: (1) Bore threading stroke: The bore thread on the bore thread holder (102) enters the lower part of the sewing machine (1) table (3) along the thread groove (103). The main control system (101) is started, the thread breaking electromagnet (82) is started and the movable connecting rod (89) is pulled back to open the blade of the thread breaking clamp (83). Then the bore thread is passed through the front fixed rod (98), then through the rear pressure groove fixed coil (99), and finally the bore thread is placed into the blade of the thread breaking electromagnet (82). The main control system (101) is started again. After the thread breaking electromagnet (82) is de-energized, it extends forward under the action of the spring and moves through the movable connecting rod (89). The second upper shear handle (87) and the second upper shear blade (84) and the second lower shear blade (85) begin to close. Before the bottom thread is cut, the second lower shear blade (85) pulls the lower part of the bottom thread into the space between the second clamping spring plate (86) and the second lower shear blade (85). When the wire cutter (83) is fully closed and cuts the bottom thread, the end of the bottom thread is clamped between the second clamping spring plate (86) and the second lower shear blade (85) under the elastic force of the second clamping spring plate (86). The second clamping spring plate (86) completes the clamping operation under the pressure of its own elastic plate. (2) Wire detection stroke: Each time the operator steps on the wire cutting pedal, the main control system (101) controls the wire detection electromagnet (45) to extend forward, causing the displacement sensor (43) and the wire detection probe (44) to move forward within the first guide rail seat (42). The wire detection probe (44) passes through the bottom of the rotary hook (4), then through the probe opening (36) on the shuttle shell (25) and enters the bobbin (37). The wire detection probe (44) cannot extend further after contacting the bottom thread on the bobbin (37). The displacement sensor (43) contains a spring, and the wire detection electromagnet (45)... The force of the forward extension must be greater than the force of the spring inside the displacement sensor (43). Under the action of the forward extension force of the line probe (44) by the line probe electromagnet (45), the line probe (44) retracts into the displacement sensor (43). The displacement sensor (43) calculates the retraction distance of the line probe (44) through potential sensing. The retraction distance of the line probe (44) is the thickness of the bottom thread on the hollow column of the bobbin (37). The preset conversion program in the host control system (101) displays the thickness of the bottom thread on the hollow column of the bobbin (37) detected by the line probe (44) as the line quantity of the bottom thread. When the bottom line is detected to be at a relatively low value, the main control system (101) directly controls the bottom line clamp (7) to extend forward and clamp the bottom line after the operator steps the cutting pedal again, clamping the bottom line before the cutting device in the machine head cuts the bottom line; When the preset full thread count is detected or the sewing machine operator changes machines and wants to start the next sewing operation, the motor (55) stops winding the thread, and then the winding electromagnet (57) stops extending forward. Under the action of the spring on the shaft of the winding electromagnet (57), the rail shaft (53) in the second guide rail seat (52) is pulled back, so that the motor (55) fixed on the rail shaft (53) is simultaneously pulled back in the slide rail (56); at the same time, the thread breaking electromagnet (82) fixed on the thread breaker base (81) begins to break the thread. After the bottom thread is spliced, the bottom thread presser (9) pulls back the U-shaped presser rod (93) under the action of the spring on the shaft of the presser electromagnet (97). Under the action of the tension, the bottom thread is fixed in the coil of the back presser groove ( 99) Pull up and pass through the middle gap to the right top of the coil (99) in the rear pressure groove. The wire breaking electromagnet (82) starts and pulls open the scissor of the wire breaking clamp (83) through the movable connecting rod (89). The bottom wire is pulled into the scissor of the wire breaking clamp (83) under the elastic action of the coil (99) in the rear pressure groove and the bottom wire itself. Then the wire breaking electromagnet (82) stops working and pulls back the wire breaking clamp (83) under the action of the spring on the shaft of the wire breaking electromagnet (82) to cut the bottom wire. At the same time as cutting the wire, the front bottom wire is pulled into the space between the second upper scissor blade (84) and the second clamping spring plate (86). The bottom wire is clamped under the elastic force of the second clamping spring plate (86). (3) Bottom thread clamping, winding, and splicing stroke: When the thread quantity detector detects that the amount of thread on the bobbin (37) is too small, the servo motor (67) of the bottom thread clamp (7) starts, and the tooth groove (65) meshing with the gear (68) causes the slide plate (62) to extend forward in the slide plate seat (61) under the rotation of the gear (68). The thread clamping shear (63) at the front end of the slide plate (62) quickly extends forward to the bobbin opening (35). When the opening and closing stop (76) at the end of the first upper shear handle (74) of the thread clamping shear (63) passes the closing shear plate (64), because the closing shear plate (64) is The arc-shaped opening and closing stop (76) is squeezed by the closing shear plate (64) during the forward extension process. The first upper shear blade (71) and the first lower shear blade (72) begin to close. Before the bottom line is cut, the first lower shear blade (72) pulls the lower part of the bottom line into the space between the first clamping spring plate (73) and the first lower shear blade (72). When the clamping shear (63) is fully closed and cuts the bottom line, the end of the bottom line is clamped into the space between the first clamping spring plate (73) and the first lower shear blade (72) under the elastic force of the first clamping spring plate (73). When the wire clamp (63) is fully closed, the servo motor (67) starts to rotate in the opposite direction under the preset program. The front gear (68) acts on the tooth groove (65) to make the slide plate (62) retract in the slide seat (61). The wire clamp (63) at the front end of the slide plate (62) clamps the end of the bobbin (37) and retracts to the front end of the air splicer (92). When the wire clamping shear (63) pulls back the bottom wire, the bottom wire clamp (9) located on the clamp base (91) starts to work under the action of the clamping electromagnet (97). The clamping electromagnet (97) causes the U-shaped clamping rod (93) fixed on the bracket (95) to start pressing down under the action of the movable shaft (94) through the movable rod (96). Under the action of the front clamping rod (98) and the rear clamping groove clamping coil (99), the four clamping holes on the U-shaped clamping rod (93) press the two crossed bottom wires into the splicing groove of the air splicer (92). When the U-shaped clamping rod (93) is pressed down to the lowest point, the start switch (104) on the air splicer (92) is pressed down through the connecting rod (105), and the air splicer (92) works and splices the bottom wires. (4) Reciprocating cycle: During the operation of the sewing machine (1), steps (2)-(3) are repeated to prepare for the next stroke. When the bobbin thread in the rotary hook (4) is insufficient, the bobbin thread is automatically replenished.

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