Thread trimming method of double-moving knife thread trimming mechanism

Abstract

The technical scheme belongs to the technical field of sewing machines, and specifically relates to a thread trimming method of a thread trimming mechanism with double movable knives, comprising a frame, a thread trimming mechanism and a rotary shuttle mechanism; the thread trimming mechanism comprises a first movable knife assembly, a second movable knife assembly and a driving assembly; the first movable knife assembly and the second movable knife assembly are both rotatably sleeved on the outer side of the adapted rotary shuttle mechanism; the driving assembly drives the first movable knife assembly to rotate around an axis between a first position and a second position, and drives the second movable knife assembly to move around the axis between a third position and a fourth position; the first movable knife assembly comprises a thread trimming movable knife 1, which is provided with a thread hole groove for a machine needle to pass through and hook the sewing thread in the sewing start stage, and a thread hooking groove 1 for the sewing thread to hook into in the finishing stage; the second movable knife assembly comprises a thread trimming movable knife 2; the thread hole groove or the thread hooking groove 1 hooks the sewing thread, drives the thread trimming movable knife 2 to rotate around the axis until it abuts against the surface of the thread trimming movable knife 1, and the cutting edges of the two thread trimming movable knives overlap to cut the sewing thread, thereby reducing thread ends and improving production efficiency.

Description

Technical Field

[0001] The technical solution relates to the technical field of sewing machines, and in particular to a thread trimming method of a thread trimming mechanism with a double movable knife. Background Art

[0002] A sewing machine is a machine that uses sewing thread to form one or more stitches on the material to be sewn, so that one or more layers of material are interwoven or sewn together. It is usually composed of a base, a needle bar mechanism, a feeding mechanism, a thread hook mechanism, a presser foot mechanism, a thread trimming mechanism and accessories, and each mechanism works in a cycle.

[0003] For example, Chinese patent CN117926509A discloses a thread cutting structure, a thread cutting method and a sewing machine for a sewing machine, wherein the thread cutting mechanism comprises an active knife, the active knife has a moving knife thread dividing tip, a first thread dividing edge, a second thread dividing edge, a moving knife thread accommodating groove, a moving knife blade and a bottom surface thread dividing opening; the thread cutting structure comprises a thread dividing hook fixedly arranged with the active knife, the thread dividing hook has a thread hooking tip portion, the thread hooking tip portion is distributed on the inner peripheral side of the active knife and on the side of the bottom surface thread dividing opening away from the moving knife thread accommodating groove, there is a thread passing space between the thread hooking tip portion and the active knife, there is a thread dividing accommodating groove between the thread hooking tip portion and the bottom surface thread dividing opening, and the thread dividing accommodating groove is communicated with the thread passing space.

[0004] During the starting and ending stages of sewing operations, long thread ends are often inevitably left on the surface of the fabric, especially the thread ends formed in the needle-starting stage, which often appear in the shape of a bird's nest, destroying the neatness and beauty of the clothing surface and lowering the overall quality standards of the finished product. Therefore, the excess thread ends need to be finely trimmed manually or automatically to ensure that the final quality of the clothing is good.

[0005] The above-mentioned sewing machine thread cutting structure, sewing machine thread cutting method and sewing machine can cut off excess thread ends and are suitable for normal clothing processing, but the problem of thread ends left on the surface of the fabric has not yet reached an ideal state and cannot meet the higher requirements of clothing production. The thread ends are still relatively obvious and still need to be trimmed twice to achieve a shorter thread cutting effect, which needs to be improved. Summary of the invention

[0006] In order to achieve the problem of achieving a shorter thread end without secondary trimming, the present technical solution provides a thread trimming method using a double-moving knife thread trimming mechanism.

[0007] The purpose of this technical solution is achieved in this way:

[0008] A thread trimming method of a double-moving-knife thread trimming mechanism, which is suitable for thread trimming in the sewing start stage and the sewing end stage of a sewing machine; the sewing machine comprises a frame, a thread trimming mechanism and a rotary hook mechanism; the thread trimming mechanism is arranged on the frame and is located below the machine needle;

[0009] The thread cutting mechanism comprises a first movable knife assembly, a second movable knife assembly and a driving assembly;

[0010] The first movable knife assembly and the second movable knife assembly are both rotatably sleeved on the outer side of the adapted rotary hook mechanism;

[0011] The driving assembly drives the first movable knife assembly to rotate around the axis of the rotary shuttle mechanism between a first position and a second position, and the driving assembly drives the second movable knife assembly to move around the axis of the rotary shuttle mechanism between a third position and a fourth position;

[0012] The first movable knife assembly includes a thread trimming movable knife; the thread trimming movable knife is provided with a thread hole slot for a machine needle to pass through and hook the sewing thread in the sewing start stage and a thread hooking slot for hooking the sewing thread in the sewing end stage, and a first cutting edge is also provided on the front side of the thread trimming movable knife;

[0013] The second movable knife assembly includes a second thread-cutting movable knife; a second cutting edge is arranged on the front side of the second thread-cutting movable knife; the second thread-cutting movable knife abuts against the surface of the first thread-cutting movable knife during rotation, so that the first cutting edge of the first thread-cutting movable knife cooperates with the second cutting edge of the second thread-cutting movable knife to cut the sewing thread;

[0014] The thread clamp is arranged on the frame, located between the first position and the second position and adjacent to the second position; when the thread trimming movable knife is reset to the second position, the thread trimming movable knife cooperates with the thread clamp to clamp the sewing thread in the thread hole groove.

[0015] Through the above technical scheme, when the thread trimming method of the thread trimming mechanism of the double movable knife is used normally, the driving component drives the thread trimming movable knife 1 to rotate around the axis, so that it rotates to switch between the first position and the second position, and is applied to the sewing start stage. After the thread trimming movable knife 1 is in the first position, it hooks the sewing thread passed by the first needle of the machine needle through the thread hole groove and locks the thread segment. After switching to the second position, the sewing thread segment is pulled and placed between the two cutters for preparation; based on the fact that the two thread trimming movable knives each have an independent driving member and a transmission rod, the two transmission rods are concentrically arranged. Similarly, the driving component drives the thread trimming movable knife 2 in the second movable knife assembly to rotate around the same axis from the third position to the fourth position. The cutting edges of the two thread trimming movable knives are aligned to form a scissors effect, and after approaching and overlapping, the sewing thread located at one of the thread trimming movable knives is accurately cut.

[0016] When sewing is nearing the end and is in the finishing stage, the first driving member drives the thread cutting knife to hook the sewing thread into the thread hooking groove, and then repeats the above-mentioned thread cutting process to achieve seamless thread cutting operation, ensure the accuracy and efficiency of thread cutting, reduce thread residue, save subsequent manual processing steps, and improve the automation level and production efficiency of the overall production process.

[0017] Preferably, the first movable knife assembly comprises a first movable knife frame and the first thread-cutting movable knife, the first movable knife frame comprises a first crank, a first connecting rod and a first ring portion, both ends of the first connecting rod are respectively hinged between one end of the first crank and the first ring portion, the first thread-cutting movable knife is arranged on the first ring portion, and the first ring portion is rotatably connected relative to the frame, so as to drive the first thread-cutting movable knife;

[0018] The second movable knife assembly includes a second movable knife frame and the second thread-cutting movable knife. The second movable knife frame includes a second crank, a second connecting rod and a second ring portion. Both ends of the second connecting rod are respectively hinged between one end of the second crank and the second ring portion. The second thread-cutting movable knife is arranged on the second ring portion. The second ring portion is coaxially arranged with the first ring portion for driving the second thread-cutting movable knife.

[0019] Through the above technical scheme, the transmission rod is driven to rotate along the axial direction of the rod, driving the first crank connected to its end to rotate synchronously, the other end of the first crank drives the hinged first connecting rod to swing, and the other end of the first connecting rod drives the hinged first ring part to swing, thereby realizing the transmission and conversion of the rotation into the rotation of the first ring part, so as to realize its rotation around the outer side of the rotary shuttle mechanism, and this rotation action drives the thread trimming movable knife 1, which completes the preparation and thread hooking action before thread trimming.

[0020] Correspondingly, the second movable knife assembly also includes a second movable knife holder and a second thread-cutting movable knife. The structural design of the second movable knife holder is similar to that of the second movable knife holder. It is independently driven to transmit and convert the rotation into the rotation of the second ring portion. The rotation drives the second thread-cutting movable knife to cut and retract the thread. During the whole process, the two movable knife assemblies work together to ensure the efficiency and precision of the thread cutting action.

[0021] Preferably, the driving assembly includes a first driving member, a second driving member and a sleeve rod structure; the sleeve rod structure includes a transmission rod 1 and a transmission rod 2 inserted into the transmission rod 1 or sleeved on the outside of the transmission rod 1; the first driving member drives the thread trimming movable knife 1 through the transmission rod 1; the second driving member drives the thread trimming movable knife 2 through the transmission rod 2;

[0022] Through the above technical solution, the first driving member drives the first thread trimming movable knife in the first movable knife assembly to rotate around the axis by driving the transmission rod 1, and the second driving member also drives the second thread trimming movable knife to rotate. The dual power source setting of each independent drive improves the overall operation efficiency and accuracy. The nested sleeve rod structure design not only effectively saves space, but also improves the compactness and stability of the structure.

[0023] Preferably, the thread trimming movable knife one is also provided with a thread hooking groove two, and the thread hooking groove two and the thread hooking groove one are respectively located on both sides of the wide width of the thread trimming movable knife one; when performing thread trimming in the finishing stage, the thread trimming movable knife one moves toward the direction of the machine needle, and the tip of the thread trimming movable knife one passes through the thread loop of the sewing thread; the thread hooking groove one and the thread hooking groove two respectively hook the sewing threads on both sides of the thread trimming movable knife one; a wire groove one is provided between the wire hole groove of the thread trimming movable knife one and the first cutting edge, and the thread hooking groove one is located in the middle of the wire groove one.

[0024] Through the above technical solution, the sewing thread on the other side of the thread loop is hooked into the second thread hook groove, which increases the length of the thread end after being cut by the first thread trimmer, reduces the operation of rearranging the thread, and improves the use efficiency. The first thread guide groove is used to accommodate the sewing thread to avoid the second thread trimmer from pressing the sewing thread when it slides against the first thread trimmer.

[0025] Preferably, the thread trimming mechanism further includes: a first transmission assembly, which is used to drive the first transmission rod to rotate; a second transmission assembly, which is used to drive the second transmission rod to rotate; the first driving member drives the first transmission assembly, and the second driving member drives the second transmission assembly.

[0026] Through the above technical solution, the two transmission components are respectively arranged on the two driving parts, so that the motor output shaft directly or indirectly transmits power to the transmission component, so as to achieve direct and efficient power transmission to the two transmission rods respectively, reduce energy loss and mechanical wear during power transmission, and ensure that the transmission rod can rotate according to the predetermined trajectory and speed.

[0027] Preferably, the first transmission assembly includes a first curved arm and a second curved arm movably arranged on the first curved arm; the other end of the first curved arm is fixed to the motor shaft of the first driving member, and the other end of the second curved arm is fixed to the transmission rod 1; the end surface of the second curved arm close to the first curved arm is provided with a slide groove, and a slider is fixed corresponding to the swinging end of the first curved arm, and the slider is arranged in the slide groove to realize sliding guidance; the swinging of the first curved arm drives the transmission rod 1 to rotate, and the other end of the transmission rod 1 directly or indirectly drives the first movable knife assembly.

[0028] Through the above technical solution, the first transmission assembly is connected between the transmission rod 1 and the first driving member for power transmission. The motor shaft of the first driving member drives the first curved arm to swing. A slider is fixed to the other end of the first curved arm and slides along the slide groove to guide the movement of the second curved arm. Therefore, the transmission rod 1 will rotate with the movement of the second curved arm, thereby realizing that the transmission rod 1 drives the first moving knife assembly.

[0029] Preferably, the second crank arm is provided with a limiting portion, which is fixed to an end of the slide slot away from the fixed end of the second crank arm, and is used to limit the sliding block from falling off the slide slot.

[0030] Through the above technical solution, the limiting portion of the second crank arm is fixed inside the slide groove away from the fixed end connected to the first crank arm, to prevent the slider from accidentally detaching from the slide groove due to various factors (such as vibration, impact, etc.) during the transmission process and avoid the risk of falling off, thereby ensuring the continuity and safety of the transmission.

[0031] Preferably, the second transmission assembly includes a third crank arm and a driving cam arranged on the third crank arm; one end of the third crank arm is fixed on the motor shaft of the second driving member, and the other swinging end thereof is provided with an adjusting part close to the driving cam, and the adjusting part acts on the driving cam so that the third crank arm transmits power to the transmission rod 2.

[0032] Through the above technical scheme, the second transmission assembly is arranged between the second transmission rod and the second driving member to realize efficient power transmission. The motor shaft of the second driving member serves as a power source to drive the third crank arm to swing periodically. The adjustment part arranged at the end of the third crank arm is closely matched with the driving cam, and the adjustment part generates relative motion with the driving cam through rolling, sliding or rotation of the adjustment part, thereby realizing effective power transmission, and then driving the second transmission rod to rotate, so that the second transmission rod drives the second moving knife assembly.

[0033] Preferably, the second transmission rod is provided with an elastic member, which is sleeved on one end of the second transmission rod provided with a second crank; the second crank is provided with a connecting block, and the elastic member is arranged between the connecting block and the frame, and its elastic force is used to reset the thread cutting movable knife 2; the first transmission rod is passed through the inside of the second transmission rod, and the length of the first transmission rod is greater than that of the second transmission rod, so that both ends of the first transmission rod protrude from both ends of the second transmission rod, and are used for connecting the first crank with the second crank arm; the second driving member has two motor shafts, one of which is connected to the third crank arm, and the other is used to connect the presser foot lifter to realize stitch length adjustment.

[0034] Through the above technical solution, the elastic part on the second transmission rod is connected between the connecting block and the frame. The second connecting block provides stable support, and its elastic force enables the second transmission component to maintain the tendency of reset movement, prompting the second thread cutting knife to return to the initial position, thereby ensuring the continuity and accuracy of the thread cutting action.

[0035] The transmission rod 2 is a hollow sleeve, and the transmission rod 1 is a core rod; the transmission rod 1 is inserted into the transmission rod 2 so that the two are concentrically arranged, and the transmission rod 1 protrudes from the two ends of the transmission rod 2 for connecting the first crank and the second crank arm. This design simplifies the transmission structure and is beneficial to the precision of the transmission.

[0036] One side of the motor shaft is specifically used to connect the third crank arm as the power source of the second transmission assembly to achieve corresponding mechanical actions. The other side is provided with a motor shaft with other purposes for connecting the presser foot lifting mechanism to achieve stitch length adjustment to meet different sewing requirements. The design of two motor shafts improves the overall performance of the drive component.

[0037] Preferably, the frame is provided with a thread sucker, and the discharge suction port of the thread sucker is received at the thread hole groove, and is used for sucking the thread ends after the thread is trimmed.

[0038] Through the above technical solution, after the thread trimmer hooks the sewing thread to the second position, the thread clamp presses the thread against the inner wall of the thread hole groove and releases it after the thread trimming is completed. At this time, the thread sucker sucks the cut thread ends through the discharge suction port for collection and processing to avoid scattering in the working area, thereby ensuring the normal operation of the equipment.

[0039] Compared with the prior art, the technical solution has the following outstanding and beneficial technical effects:

[0040] 1. This technical solution drives the thread trimming movable knife 1 of the first movable knife assembly and the thread trimming movable knife 2 of the second movable knife assembly to rotate through a driving assembly, so that the two thread trimming movable knives rotate axially around the outer side of the rotary hook mechanism, so as to realize the operation of hooking the thread in the thread hole groove at the start of sewing, hooking the thread in the thread hooking groove 1 and the thread hooking groove 2 at the end of sewing, and the two knives are relatively close to cut the sewing thread, thereby reducing thread residue and improving production automation and production efficiency;

[0041] 2. The technical solution is transmitted through a sleeve rod structure, which includes a transmission rod 1 and a transmission rod 2. The transmission rod 1 is inserted into the transmission rod 2. The two transmission rods are concentrically arranged, corresponding to the first movable knife assembly and the second movable knife assembly respectively. This design simplifies the transmission structure and is beneficial to the precision of the transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 Schematic diagram of the overall structure of this embodiment;

[0043] Figure 2 For this embodiment Figure 1 Schematic diagram from another perspective;

[0044] Figure 3 Schematic diagram of the transmission structure of this embodiment;

[0045] Figure 4 It is a schematic diagram of the installation of the first thread trimming movable knife and the second thread trimming movable knife in the embodiment;

[0046] Figure 5 It is a partial structural schematic diagram of the first movable knife assembly and the second movable knife assembly in the embodiment;

[0047] Figure 6 It is a partial exploded schematic diagram of the first moving knife assembly in the embodiment;

[0048] Figure 7 A partial exploded schematic diagram of the second moving knife assembly in the embodiment;

[0049] Figure 8 Schematic diagram of the coordination of the first thread trimming movable knife and the second thread trimming movable knife in the embodiment;

[0050] Fig. 9 It is a schematic diagram of the operation structure of the line hole slot hook line in the embodiment;

[0051] Fig.10 It is a schematic diagram of the operation structure of the wire hooking groove 1 and the wire hooking groove 2 in the embodiment;

[0052] Fig.11 Schematic diagram of the exploded structure of the first transmission assembly and the second transmission assembly in the embodiment.

[0053] Reference numerals: 1, frame; 2, first movable knife assembly; 21, thread trimming movable knife 1; 22, first movable knife holder; 221, first crank; 222, first connecting rod; 223, first ring; 3, second movable knife assembly; 31, thread trimming movable knife 2; 32, second movable knife holder; 321, second crank; 322, second connecting rod; 323, second ring; 4, driving assembly; 41, first driving member; 42, second driving member; 5, sleeve rod structure; 51, transmission rod 1; 52, transmission Rod 2; 6. Thread hole slot; 71. Thread hook slot 1; 72. Thread hook slot 2; 8. First transmission assembly; 81. First curved arm; 82. Second curved arm; 9. Second transmission assembly; 91. Third curved arm; 92. Driving cam; 10. Slide slot; 11. Sliding block; 12. Limiting part; 13. Adjusting part; 14. Elastic part; 15. Connecting block; 16. Thread clamp; 17. Thread sucker; 181. Thread guide slot 1; 182. Thread guide slot 2; 100. Rotating hook mechanism; 200. Needle. DETAILED DESCRIPTION

[0054] The specific implementation of the technical solution is further described in detail below with reference to the accompanying drawings.

[0055] Example:

[0056] See also Figure 1 and Figure 2 A thread trimming method of a double-movable knife thread trimming mechanism includes a frame 1, which is the main body of the sewing machine device, and also includes a thread trimming mechanism, which is installed below the frame 1. This embodiment shows that a rotary shuttle mechanism 100 is installed in the frame 1 and a machine needle 200 is arranged above the frame 1. The rotary shuttle mechanism 100 is a prior art and will not be described in detail here. The lower end of the machine needle 200 is used to pass the sewing thread, and it can be lifted up or lowered for use.

[0057] See also Figure 3and Figure 5 The thread trimming mechanism includes a first movable knife assembly 2, a second movable knife assembly 3 and a driving assembly 4. The first movable knife assembly 2 and the second movable knife assembly 3 are both rotatably mounted on the outer peripheral side of the adapted rotary shuttle mechanism 100, with the rotary shuttle mechanism 100 as the rotation axis. The first movable knife assembly 2 is used to hook the sewing thread, and the second movable knife assembly 3 cooperates with the first movable knife assembly 2 as a thread trimmer. The driving assembly 4 includes a first driving member 41 and a second driving member 42. Both driving members can use motors. The first driving member 41 and the second driving member 42 respectively correspond to each other through the sleeve rod structure 5 and indirectly drive the first movable knife assembly 2 and the second movable knife assembly 3 as a power source.

[0058] The second driving member 42 can be configured as a dual-axis motor, one end of the motor shaft of which drives the second movable knife assembly 3, and the other end is used to drive another set of mechanisms to operate, such as a presser foot lifting mechanism or a needle distance adjustment mechanism. The technical solution of how to share a motor between the two sets of mechanisms is existing technology and will not be elaborated here.

[0059] The sleeve rod structure 5 includes a transmission rod 1 51 and a transmission rod 2 52. The transmission rod 2 52 is inserted into the transmission rod 1 51 or is sleeved on the outside of the transmission rod 1 51. This embodiment shows the situation where the transmission rod 1 51 is inserted into the transmission rod 2 52. The transmission rod 2 52 is a sleeve structure, and the transmission rod 1 51 is a rod core structure. The transmission rod 1 51 and the transmission rod 2 52 can rotate independently of each other and are concentrically arranged. The two ends of the transmission rod 1 51 respectively pass through the two ends of the transmission rod 2 52.

[0060] A first transmission assembly 8 is provided between the first driving member 41 and the transmission rod 51. The first transmission assembly 8 transmits the rotation of the motor shaft of the first driving member 41 to the rotation of the transmission rod 51. The first transmission assembly 8 includes a first crank arm 81 and a second crank arm 82 movably arranged on the first crank arm 81. One end of the first crank arm 81 is fixed on the motor shaft of the first driving member 41, and the second crank arm 82 is located on the side of the first crank arm 81 away from the first driving member 41. The first crank arm 81 swings to drive the second crank arm 82 to run synchronously. The specific transmission method is achieved by A slider 11 protrudes from the other end of the first crank arm 81 toward the second crank arm 82. The slider 11 is a rectangular block. A slide groove 10 is provided on the end face of the second crank arm 82 close to the first crank arm 81, which runs through both ends along the length direction of the second crank arm 82. The width of the slider 11 is adapted to the groove width of the slide groove 10, so that the slider 11 can be embedded in the slide groove 10 and slide along the length direction of the slide groove 10, thereby pushing the second crank arm 82 to swing. Based on the fact that the other end of the second crank arm 82 is fixed on the transmission rod 51, the transmission rod 51 is driven to rotate.

[0061] The transmission is in the form of a slider 11 and a slide slot 10 assembly, and through the forward and reverse rotation of the motor, the trajectories of the forward and reverse motions of the thread trimming moving knife 21 are made consistent to ensure the consistency of the knife traces.

[0062] The second crank arm 82 is provided with a limiting portion 12, which is fixed in the slide groove 10 and is located in the groove at an end away from the fixed end of the second crank arm 82. In this embodiment, the limiting portion 12 is preferably a bolt for the slider 11 to abut against, and is used to limit the slider 11 from accidentally detaching from the through end of the slide groove 10, thereby improving the guiding stability.

[0063] A second transmission assembly 9 is arranged between the second driving member 42 and the transmission rod 2 52. The second transmission assembly 9 is located on the same side as the first transmission assembly 8 and can transmit the rotation of the motor shaft of the second driving member 42 to the rotation of the transmission rod 2 52. The third transmission assembly 9 includes a third crank arm 91 and a driving cam 92. One end of the third crank arm 91 is locked and fixed on the motor shaft of the second driving member 42, and the other end is fixed with an adjusting portion 13, which protrudes toward the driving cam 92. The adjusting portion 13 can produce relative motion with the driving cam 92 by rolling, sliding or rotating. The driving cam 92 shown in this embodiment is provided with a cam groove, and the protrusion degree of the inner wall of the groove varies. The adjusting portion 13 is embedded in the driving cam 92 and contacts with the inner wall of the groove. When the third crank arm 91 rotates to drive the adjusting portion 13, the adjusting portion 13 contacts the inner wall of the groove to realize the intermittent motion of the driving cam 92. Based on the fact that one end of the driving cam 92 is fixed to the end of the transmission rod 2 52, the transmission rod 2 52 is driven to rotate.

[0064] See also Figure 5 and Figure 6 The first movable knife assembly 2 includes a thread trimming movable knife 21 and a first movable knife holder 22, wherein the first movable knife holder 22 includes a first crank 221, a first connecting rod 222 and a first ring portion 223. The lower end of the first crank 221 is sleeved on the end of the transmission rod 51 away from the first driving member 41 and fixed, and the other end is hinged to the lower end of the first connecting rod 222 upwardly, and the other end of the first connecting rod 222 is hinged to the first ring portion 223 to form two hinge points. The first ring portion 223 is rotatably sleeved on the rotary hook mechanism 100. When the transmission rod 51 rotates, the transmission rod 51 drives the first crank 221 to rotate, and the first driving member 41 drives the first connecting rod 222 to swing, so that the first connecting rod 222 drives the first ring portion 223 to rotate. The thread trimming movable knife 21 is installed on the first ring portion 223, which is in the shape of an arc sheet, and drives the thread trimming movable knife 21 to switch between different positions.

[0065] See also Figure 5 and Figure 7The second movable knife assembly 3 is located at the rear side of the first movable knife assembly 2, and includes a second crank 321, a second connecting rod 322 and a second ring portion 323. The lower end of the second crank 321 is sleeved on the end of the transmission rod 2 52 away from the second driving member 42 and fixed, and the other end is hinged to the lower end of the second connecting rod 322 upward, and the other end of the second connecting rod 322 is hinged on the second ring portion 323, thereby forming two hinge points, and the second ring portion 323 is rotatably sleeved on the rotary shuttle mechanism 100 and adjacent to the first ring portion 223. When the transmission rod 2 52 rotates, the transmission rod 2 52 drives the second crank 321 to rotate, and the second driving member 42 drives the second connecting rod 322 to swing, so that the second connecting rod 322 drives the second ring portion 323 to rotate, based on the second ring portion 323 is installed with the thread cutting movable knife 2 31, which is in the shape of an arc sheet, driving the thread cutting movable knife 1 21 to rotate to complete the switching between different positions.

[0066] The second crank 321 is provided with a connecting block 15, which is located above the second crank 321. An elastic member 14 is sleeved on one end of the transmission rod 52 close to the second crank 321, which is preferably a torsion spring, which is respectively arranged between the connecting block 15 and the frame 1. The elastic force of the elastic member acts on the second crank 321, so that the second crank 321 can be quickly reset after the transmission rod 52 is separated from the inner surface of the driving cam 92, so that the thread cutting movable knife 31 maintains a tendency to reset to the initial position.

[0067] See also Figure 8 The thread trimming movable knife 21 is provided with a thread hole groove 6, a thread hooking groove 71 and a thread hooking groove 72, and each groove runs through the thickness direction of the thread trimming movable knife 21. The thread hole groove 6 and the thread hooking groove 71 are arranged along the rotation direction of the thread trimming movable knife 21. The thread hole groove 6 is located at the thread hooking groove 71 and is far away from the tip of the thread trimming movable knife 21. The tip of the knife has a first cutting edge with different flatness. The thread hole groove 6 is used for the needle 200 to pass through and hook the sewing thread in the sewing stage.

[0068] The thread hooking groove 1 71 and the thread hooking groove 2 72 are respectively located on the opposite sides of the middle part of the thread trimming movable knife 1 21 in a one-to-one correspondence, and both have openings facing outward. When the tip of the knife passes through the thread loop, the openings on both sides are used to hook the sewing threads on both sides into the corresponding thread hooking grooves at the end of the sewing stage to achieve thread hooking. In this embodiment, the thread trimming movable knife 1 21 is provided with two guide wire grooves for accommodating sewing threads, including guide wire groove 1 181 and guide wire groove 2 182, wherein guide wire groove 1 181 is located between the thread hole groove 6 and the first cutting edge, and covers the thread hooking groove 1 71, guiding the sewing thread to the thread hole groove 6, the front end edge of the guide wire groove 1 181 is provided with the first cutting edge, and the front end of the guide wire groove 1 181 can be a through groove or a non-through groove, and the other guide wire groove 2 182 is arranged corresponding to the thread hooking groove 2 72, and is used to guide the sewing thread to the thread hooking groove 2 72.

[0069] The second thread trimming movable knife 31 is arranged above the outer side of the first thread trimming movable knife 21, and the front end of the second thread trimming movable knife 31 is close to the upper surface of the first thread trimming movable knife 21 and slides. The front end of the second thread trimming movable knife 31 is provided with a second cutting edge. When the second thread trimming movable knife 31 and the first thread trimming movable knife 21 approach each other, the thread hole groove 6 or the thread hook groove 71 will bring the sewing thread to the second cutting edge. The sewing thread is not subjected to pressure on the first cutting edge and will not be cut until it coincides with the second cutting edge, at which time the sewing thread will be cut, ensuring the shearing of the thread head at the start of sewing and the breaking of the thread at the end of sewing.

[0070] See also Fig.11 The frame 1 is also provided with a thread clamp 16, which is located on the inner side of the thread trimming movable knife 21 and can be aligned with the thread hole slot 6. In the sewing start stage, when the sewing thread is ready to be cut, the thread clamp 16 clamps the sewing thread passing through the thread hole slot 6 to the inner wall of the thread trimming movable knife 21, locks the upper thread and stops supplying the upper thread to the needle 200 (the thread passing through the needle 200 of the sewing machine is the upper thread, and the thread in the rotary shuttle mechanism 100 at the bottom of the sewing machine is the lower thread), so that the stitches of the subsequent second stitch are stable and not easy to fall apart after sewing.

[0071] The frame 1 is further provided with a thread sucker 17, the discharge suction port of the thread sucker 17 is received at the thread hole groove 6, and is used for sucking the thread ends after the thread is cut.

[0072] The specific working process of this program is as follows:

[0073] The technical solution drives the transmission rod 51 through the first driving member 41 to drive the thread cutting movable knife 21 in the first movable knife assembly 2 to rotate around the axis, and similarly, the second driving member 42 drives the thread cutting movable knife 31 to rotate around the same axis; in the sewing starting stage, the thread hole slot 6 is located directly below the machine needle 200, and the machine needle 200 performs the first needle lowering action: the machine needle 200 passes downward through the fabric and the thread hole slot 6 and enters the rotary shuttle mechanism 100 to hook the bottom line and then withdraws, the thread take-up rod picks up the thread and drives the upper thread on the needle 200 to retreat, and the thread take-up rod picks up the thread During the threading process, the surface thread is stored, the sewing thread head on the needle 200 is kept in the thread hole groove 6, the thread trimming movable knife 21 is rotated to make the thread clamp 16 clamp the thread head, and the second needle is lowered to lock the thread, and the thread trimming movable knife 2 31 is driven to cooperate with the thread cutting; when it is in the finishing stage, the first driving member 41 drives the thread trimming movable knife 21 forward to pass through the thread loop, and the openings of the thread hooking groove 1 71 and the thread hooking groove 2 72 are hooked into the surface and bottom lines, and then the above-mentioned thread cutting operation is repeated to reduce the residual thread heads, eliminate the subsequent manual processing steps, and improve production automation and production efficiency.

[0074] The present application also claims protection for a thread trimming method of a sewing mechanism with a double-moving knife, which is implemented by the double-moving knife; the thread trimming method includes a sewing start stage and a sewing end stage, and the steps are as follows:

[0075] S1, initial state, in the sewing start stage, the thread trimming movable knife 1 21 is in the initial first position, and the thread trimming movable knife 2 31 is in the initial third position; the two thread trimming movable knives are both located on the same side, rotated relatively to the right side around the rotary shuttle mechanism, slightly staggered at this position, and not required to be in the same position, until the sewing fabric is placed.

[0076] S2, in the sewing start stage, the first driving member 41 drives the thread trimming movable knife 21 to move toward the machine needle, and rotates to the position of the thread hole slot 6 which is directly below the position of the machine needle. The thread passing through the machine needle is the upper thread, and the thread in the rotary shuttle mechanism at the bottom of the sewing machine is the lower thread; the electronic control system of the sewing machine controls the machine needle to perform the first needle lowering action in the sewing start stage, wherein the machine needle first passes downward through the needle plate and the sewing fabric, then passes downward through the thread hole slot 6 and enters the rotary shuttle mechanism to hook the lower thread, and then exits the thread hole slot 6 upward and is lifted to a suitable position above the frame 1; the thread take-up rod of the sewing machine takes up the thread upward and drives the upper thread on the machine needle to retreat, and the upper thread storage is completed in this process; the sewing thread head on the machine needle is kept in the thread hole slot 6;

[0077] S3, the thread trimming movable knife 1 21 moves to the first position, and the thread hole slot 6 of the thread trimming movable knife 1 21 brings the sewing thread close to the cutting edge of the thread trimming movable knife 2 31; the thread trimming movable knife 2 31 moves to the fourth position, and the second driving member 42 drives the thread trimming movable knife 2 31 to slide on the surface of the thread trimming movable knife 1 21, and the first cutting edge and the second cutting edge approach each other; when the thread hole slot 6 passes through the thread clamp 16, the thread trimming movable knife 1 21 retreats to the designated position and pauses at the existing position with the thread trimming movable knife 2 31, and the thread clamp 16 locks the upper thread and cannot withdraw from the thread hole slot 6.

[0078] S4, such as Fig. 9 As shown, the needle performs the second needle lowering action, and the upper thread on the needle is locked with the lower thread in the rotary hook mechanism 100, tightening the upper thread to prevent the second needle from lifting and bringing it out of the thread hole groove 6, ensuring that the stitches cut later are not easy to loosen until the second needle thread locking is completed;

[0079] S5, the thread trimming movable knife 1 21 continues to reset to the first position, the thread trimming movable knife 2 31 continues to move toward the fourth position, the two driving members continue to drive the thread trimming movable knife 2 31 to approach the thread trimming movable knife 1 21, and continue to slide forward on the surface of the thread trimming movable knife 1 21, and the thread trimming movable knife 1 21 is reset; after the thread trimming movable knife 2 31 reaches the fourth position, it completes the reset to the third position, and the cutting edge of the thread trimming movable knife 2 31 and the cutting edge of the thread trimming movable knife 1 21 approach each other and overlap; the thread trimming is completed, the sewing thread in the thread hole groove 6 is cut, and the thread head of the upper thread on the needle at the sewing starting stage meets the required length, and the thread sucker 17 sucks away the thread head through the air suction port;

[0080] S6, the needle continues sewing until the current sewing operation is finished, and the needle is lifted above the frame 1;

[0081] S7, execute the thread trimming in the finishing stage, the first driving member 41 drives the thread trimming movable knife 21 to move toward the direction of the needle until the tip of the thread trimming movable knife 21 passes through the thread loop of the sewing thread and reaches the set position. At this time, the openings of the two thread hooking grooves on the opposite sides of the thread trimming movable knife 21 are respectively facing the sewing threads on both sides, and the sewing threads are the twisted combination of the upper thread and the lower thread, and the thread trimming movable knife 2 31 remains stationary; the thread trimming movable knife 21 is driven back in the reverse direction again, and the thread suction device 17 is started to introduce the sewing threads on both sides through the corresponding openings through the flow of wind, such as Fig.10 As shown, the thread hooking groove 1 71 and the thread hooking groove 2 72 respectively hook the sewing threads on both sides, and the sewing threads remain in the corresponding thread hooking grooves, and the continuous sewing threads bypass the bottom of the thread trimming movable knife 1 21;

[0082] S8, the first driving member 41 drives the thread trimming movable knife 1 21 to retreat, and the second driving member 42 drives the thread trimming movable knife 2 31 to move toward the thread trimming movable knife 1 21, and the thread hooking groove 1 71 brings the sewing thread close to the cutting edge of the thread trimming movable knife 2 31, and the thread trimming movable knife 2 31 slides on the surface of the thread trimming movable knife 1 21, and the cutting edges of the thread trimming movable knife 2 31 and the thread trimming movable knife 1 21 overlap and cut the sewing thread in the thread hole groove 6;

[0083] S9, the thread trimming is completed, the second driving member 42 drives the second thread trimming movable knife 31 to reset, and the first driving member 41 drives the first thread trimming movable knife 21 to reset, and the thread trimming is completed. The above-mentioned operation cycle of S1-S10 can be repeated later.

[0084] The above shows and describes the basic principle and main features of the technical solution and the advantages of the technical solution. The technicians in this industry should understand that the technical solution is not limited by the above embodiments. The above embodiments and the description are only to illustrate the principle of the technical solution. Without departing from the spirit and scope of the technical solution, the technical solution will have various changes and improvements, which fall within the scope of the technical solution to be protected. The scope of protection claimed by the technical solution is defined by the attached claims and their equivalents.

Claims

1. A thread trimming method for a double-moving-knife thread trimming mechanism, which is suitable for thread trimming at the beginning and end stages of a sewing machine; the sewing machine comprises a frame (1), a thread trimming mechanism and a rotary hook mechanism; the thread trimming mechanism is arranged on the frame (1) and is located below the machine needle; Features: The thread cutting mechanism comprises a first movable knife assembly (2), a second movable knife assembly (3) and a driving assembly (4); The first movable knife assembly (2) and the second movable knife assembly (3) are both rotatably sleeved on the outer side of the adapted rotary hook mechanism; The driving assembly (4) drives the first movable knife assembly (2) to rotate around the axis of the rotary shuttle mechanism between a first position and a second position, and the driving assembly (4) drives the second movable knife assembly (3) to move around the axis of the rotary shuttle mechanism between a third position and a fourth position; The first movable knife assembly (2) comprises a thread-cutting movable knife (21); the thread-cutting movable knife (21) is provided with a thread hole groove (6) for a machine needle to pass through and to hook the sewing thread in the sewing start stage, and a thread hooking groove (71) for hooking the sewing thread in the sewing end stage, and a first cutting edge is also provided on the front side of the thread-cutting movable knife; The second movable knife assembly (3) comprises a thread-cutting movable knife (2) (31); a second cutting edge is arranged on the front side of the thread-cutting movable knife (31); the thread-cutting movable knife (2) (31) abuts against the surface of the thread-cutting movable knife (21) during rotation, so that the first cutting edge of the thread-cutting movable knife (21) cooperates with the second cutting edge of the thread-cutting movable knife (31) to cut the sewing thread; A thread clamp (16) is arranged on the frame (1) and is located between the first position and the second position and adjacent to the second position; when the thread trimming movable knife (21) is reset to the second position, the thread trimming movable knife (21) cooperates with the thread clamp (16) to clamp the sewing thread in the thread hole groove (6); The thread trimming method includes thread trimming at the beginning of sewing and thread trimming at the end of sewing. The steps are as follows: S1, initial state, the thread trimming movable knife 1 (21) and the thread trimming movable knife 2 (31) are both located on the same side of the frame (1), the thread trimming movable knife 1 (21) is in the initial first position, and the thread trimming movable knife 2 (31) is in the initial third position; the fabric to be sewn is placed; S2, in the sewing start stage, the thread cutting movable knife (21) moves toward the direction of the machine needle, and the thread cutting movable knife (21) rotates until the position of the thread hole slot (6) is directly below the position of the machine needle, and the thread cutting movable knife (21) is in the second position; the machine needle first passes through the thread hole slot (6) downward, then leaves the thread hole slot (6) upward and is lifted to a suitable position above the frame (1), completing the first needle lowering action of the machine needle; the thread take-up rod of the sewing machine takes up the thread upward and drives the upper thread on the machine needle to retreat; the sewing thread on the machine needle remains in the thread hole slot (6); S3, the thread trimming movable knife 1 (21) moves to the first position, and the thread trimming movable knife 2 (31) moves to the fourth position; the thread trimming movable knife 1 (21) retreats to a position close to the thread trimming movable knife 2 (31); the thread hole groove (6) of the thread trimming movable knife 1 (21) brings the sewing thread close to the second cutting edge of the thread trimming movable knife 2 (31); the thread trimming movable knife 2 (31) slides on the surface of the thread trimming movable knife 1 (21), and the first cutting edge and the second cutting edge approach each other; when the thread hole groove (6) passes through the thread clamp (16), the upper thread in the thread hole groove (6) is pressed by the thread clamp (16), and the upper thread is in a locked thread state and cannot exit the thread hole groove (6); the thread trimming movable knife 1 (21) and the thread trimming movable knife 2 (31) are paused; S4, the needle performs the second sewing action, and the upper thread on the needle is locked with the lower thread in the rotary hook mechanism; S5, the thread-cutting movable knife 1 (21) continues to reset to the first position, and the thread-cutting movable knife 2 (31) continues to move toward the fourth position; the second cutting edge of the thread-cutting movable knife 2 (31) and the first cutting edge of the thread-cutting movable knife 1 (21) cut the sewing thread in the thread hole groove (6) when they overlap; the thread-cutting movable knife 1 (21) is reset; after the thread-cutting movable knife 2 (31) reaches the fourth position, it is reset to the third position; the thread cutting is completed in the sewing start stage; S6, the needle continues sewing until the current sewing operation is finished, and the needle is lifted above the frame; S7, executing the thread trimming in the finishing stage, the thread trimming movable knife 1 (21) moves to the second position, and the thread trimming movable knife 1 (21) rotates until the thread hooking groove 1 (71) is directly below the needle, and the thread hooking groove 1 (71) hooks the sewing thread; S8, after the thread-cutting movable knife 1 (21) moves to the second position, it returns to the first position, and the thread-cutting movable knife 2 (31) moves to the fourth position; the thread-cutting movable knife 1 (21) and the thread-cutting movable knife 2 (31) move toward each other, the thread-hooking groove 1 (71) of the thread-cutting movable knife 1 (21) brings the sewing thread close to the cutting edge of the thread-cutting movable knife 2 (31), and the thread-cutting movable knife 2 (31) slides on the surface of the thread-cutting movable knife 1 (21), and the cutting edge of the thread-cutting movable knife 2 (31) and the cutting edge of the thread-cutting movable knife 1 (21) overlap, and the sewing thread in the thread-hooking groove 1 (71) is cut; S9, the thread trimming movable knife 1 (21) is reset; after the thread trimming movable knife 2 (31) reaches the fourth position, it is reset to the third position; the thread trimming is completed in the final stage; The thread trimming movable knife (21) is also provided with a thread hooking groove (72), and the thread hooking groove (72) and the thread hooking groove (71) are respectively located on both sides of the wide width of the thread trimming movable knife (21); When executing the thread trimming in the finishing stage, the thread trimming movable knife 1 (21) moves toward the direction of the machine needle, and the tip of the thread trimming movable knife 1 (21) passes through the thread loop of the sewing thread; the thread hooking groove 1 (71) and the thread hooking groove 2 (72) respectively hook the sewing thread on both sides of the thread trimming movable knife 1 (21); A wire groove (181) is arranged between the wire hole groove (6) of the thread cutting movable knife (21) and the first cutting edge, and the wire hook groove (71) is located in the middle of the wire groove (181).

2. The thread trimming method of the double-moving-knife thread trimming mechanism according to claim 1, characterized in that: The first movable knife assembly (2) comprises a first movable knife frame (22) and the thread-cutting movable knife (21); the first movable knife frame (22) comprises a first crank (221), a first connecting rod (222) and a first ring portion (223); two ends of the first connecting rod (222) are respectively hinged between one end of the first crank (221) and the first ring portion (223); the thread-cutting movable knife (21) is arranged on the first ring portion (223); the first ring portion (223) is rotatably connected relative to the frame (1) and is used to drive the thread-cutting movable knife (21); The second movable knife assembly (3) comprises a second movable knife frame (32) and the second thread-cutting movable knife (31); the second movable knife frame (32) comprises a second crank (321), a second connecting rod (322) and a second ring portion (323); the two ends of the second connecting rod (322) are respectively hinged between one end of the second crank (321) and the second ring portion (323); the second thread-cutting movable knife (31) is arranged on the second ring portion (323); the second ring portion (323) and the first ring portion (223) are coaxially arranged for driving the second thread-cutting movable knife (31).

3. The thread trimming method of the double-moving-knife thread trimming mechanism according to claim 2, characterized in that: The driving assembly (4) comprises a first driving member (41), a second driving member (42) and a sleeve rod structure (5); The sleeve rod structure (5) comprises a transmission rod 1 (51) and a transmission rod 2 (52) inserted into the transmission rod 1 (51) or sleeved on the outside of the transmission rod 1 (51); The first driving member (41) drives the first thread-cutting movable knife (21) via the first transmission rod (51); and the second driving member (42) drives the second thread-cutting movable knife (31) via the second transmission rod (52).

4. The thread trimming method of the double-moving-knife thread trimming mechanism according to claim 3, characterized in that: The thread cutting mechanism also includes: A first transmission assembly (8), used for driving the transmission rod 1 (51) to rotate; A second transmission assembly (9), used for driving the second transmission rod (52) to rotate; The first driving member (41) drives the first transmission assembly (8), and the second driving member (42) drives the second transmission assembly (9).

5. The thread trimming method of the double-moving-knife thread trimming mechanism according to claim 4, characterized in that: The first transmission assembly (8) comprises a first crank arm (81) and a second crank arm (82) movably disposed on the first crank arm (81); The other end of the first crank arm (81) is fixed on the motor shaft of the first driving member (41), and the other end of the second crank arm (82) is fixed on the transmission rod 1 (51); A slide groove (10) is provided on the end surface of the second crank arm (82) close to the first crank arm (81); a sliding block (11) is fixed corresponding to the swing end of the first crank arm (81); the sliding block (11) is arranged in the slide groove (10) to achieve sliding guidance; The swing of the first curved arm (81) drives the transmission rod (51) to rotate, and the other end of the transmission rod (51) directly or indirectly drives the first movable knife assembly (2).

6. The thread trimming method of the double-moving-knife thread trimming mechanism according to claim 5, characterized in that: The second crank arm (82) is provided with a limiting portion (12), which is fixed to an end of the slide groove (10) away from the fixed end of the second crank arm (82) and is used to limit the sliding block (11) from falling off the slide groove (10).

7. The thread trimming method of the double-moving-knife thread trimming mechanism according to claim 4, characterized in that: The second transmission assembly (9) comprises a third crank arm (91) and a driving cam (92) arranged on the third crank arm (91); One end of the third crank arm (91) is fixed on the motor shaft of the second driving member (42), and the other swinging end thereof is provided with an adjusting portion (13) near the driving cam (92). The adjusting portion (13) acts on the driving cam (92) so that the third crank arm (91) transmits power to the second transmission rod (52).

8. The thread trimming method of the double-movable-knife thread trimming mechanism according to claim 7, characterized in that: The second transmission rod (52) is provided with an elastic member (14), which is sleeved on one end of the second transmission rod (52) provided with a second crank (321); The second crank (321) is provided with a connecting block (15), and the elastic member (14) is arranged between the connecting block (15) and the frame (1), and its elastic force is used to reset the second thread trimming movable knife (31); The transmission rod 1 (51) is inserted into the transmission rod 2 (52), and the length of the transmission rod 1 (51) is greater than that of the transmission rod 2 (52), so that both ends of the transmission rod 1 (51) protrude from both ends of the transmission rod 2 (52), and are used for connecting the first crank (221) and the second crank arm (82); The second driving member (42) has two motor shafts, one of which is connected to the third crank arm (91), and the other is connected to the presser foot lifter to adjust the stitch length.

9. The thread trimming method of the double-movable-knife thread trimming mechanism according to any one of claims 1 to 8, characterized in that: The frame (1) is provided with a thread sucker (17), the discharge suction port of the thread sucker (17) being connected to the thread hole groove (6) and being used for sucking the thread ends after the thread is cut.

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