Sewing machine, thread trimming mechanism and double-moving-cutter assembly

Abstract

The invention belongs to the technical field of sewing machines, and particularly relates to a thread trimming mechanism of a sewing machine. The first movable cutter assembly is used for hooking a sewing thread, and the second movable cutter assembly is matched with the first movable cutter assembly to cut off the sewing thread; the second moving cutter is arranged above the first moving cutter, the front end of the second moving cutter is attached to the upper surface of the first moving cutter, and a second cutting edge is arranged at the front end part of the second moving cutter; when the second movable cutter slides to a set position on the surface of the first movable cutter, the second cutting edge and the first cutting edge are matched to cut off the sewing thread. Under the condition that one movable cutter retreats backwards and hooks the thread, the other movable cutter moves forwards and is matched with the thread cutting; the two movable cutters jointly complete thread trimming, the thread trimming position is closer to a machine needle, and the effect of shorter thread ends is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of sewing machines, and in particular relates to a thread trimming mechanism of a sewing machine. Background Art

[0002] The sewing machine is mainly composed of a base (i.e., the casing and bottom plate), a needle bar mechanism, a feeding mechanism, a thread hook mechanism, a presser foot mechanism, a thread trimming mechanism and accessories. Through the reasonable coordination of the movements of each mechanism and the circulation work, the sewing materials are sewed together.

[0003] During the sewing machine's initial and final stages of sewing, long thread ends are left on the fabric surface. These thread ends can form a bird's nest-like pattern on the finished garment, affecting the overall quality of the garment. To ensure the quality of the garment, these thread ends must be manually trimmed, which increases labor intensity and affects production efficiency.

[0004] To improve sewing efficiency, automatic thread trimming mechanisms are commonly used in sewing equipment. This not only allows for smoother sewing but also reduces thread ends in clothing, improving the efficiency of subsequent finishing. CN202322683791.X discloses a single-action knife anti-bird nest thread trimming mechanism and a sewing machine. This technical solution can cut off excess sewing thread at the beginning of the seam and also cut the thread after the sewing process is completed.

[0005] In actual application, this technical solution still leaves less than ideal thread ends on the fabric surface. For some ordinary clothes, the thread ends are generally long enough to avoid the need for manual trimming. However, for some high-end clothes, the thread ends left on the fabric are still quite long and still require manual trimming. Therefore, the applicant has further researched and developed a new technical solution to achieve the effect of even shorter thread ends. Summary of the Invention

[0006] The object of the present invention is to provide a sewing machine, a thread trimming device and a double-knife assembly capable of achieving shorter thread ends when trimming threads.

[0007] The object of the present invention is achieved like this:

[0008] The double movable knife assembly of the thread trimming mechanism of the sewing machine includes a first movable knife assembly and a second movable knife assembly; the first movable knife assembly is used to hook the sewing thread, and the second movable knife assembly cooperates with the first movable knife assembly to cut the sewing thread;

[0009] The first movable knife assembly includes a first movable knife holder and a first movable knife; a first ring portion is provided in the middle of the first movable knife holder, and the first ring portion is used to be rotatably mounted on the outer side of the rotary hook mechanism; a first driving portion is provided on one side of the first ring portion, and the first movable knife is provided on the other side; a first cutting edge is provided at the tip of the first movable knife;

[0010] The second movable knife assembly includes a second movable knife holder and a second movable knife; a second ring portion is provided in the middle of the second movable knife holder, and the second ring portion is used to be rotatably sleeved on the outer side of the rotary hook mechanism; a second driving portion is provided on one side of the second ring portion, and the second movable knife is provided on the other side;

[0011] The second movable knife is arranged above the first movable knife, the front end of the second movable knife is in contact with the upper surface of the first movable knife, and the front end of the second movable knife is provided with a second cutting edge; when the second movable knife slides to a set position on the surface of the first movable knife, the second cutting edge cooperates with the first cutting edge to cut the sewing thread.

[0012] Preferably, a front hole groove and a thread hooking groove are provided on the first movable knife, and the front hole groove and the thread hooking groove are arranged along the rotation direction of the first movable knife; the front hole groove is provided at the tip of the first movable knife, and the first cutting edge is provided at the front edge of the front hole groove; the thread hooking groove is provided in the middle of the first movable knife, and an opening for hooking the thread is provided on the thread hooking groove; a accommodating groove for accommodating the sewing thread is provided between the front hole groove and the thread hooking groove.

[0013] Preferably, the first ring portion and the second ring portion are arranged in parallel front and back, or the first ring portion and the second ring portion are arranged inside and outside the ring portion;

[0014] The first ring portion and the second ring portion are arranged on the same axis.

[0015] Preferably, the first driving portion and the second driving portion are both located on the same side;

[0016] The front hole slot and / or the thread hook slot allow a needle of a sewing machine to pass through.

[0017] The thread trimming mechanism of the sewing machine includes the double-moving knife assembly described above; and further includes:

[0018] a first transmission assembly configured to drive a first driving portion of the first ring portion;

[0019] a second transmission assembly configured to drive a second driving portion of the second ring portion;

[0020] At least one driving assembly, which is used to drive the first transmission assembly and / or the second transmission assembly.

[0021] Preferably, the driving assembly is provided with one, the driving assembly being a motor, the motor shaft of the motor driving the first transmission assembly and the second transmission assembly;

[0022] The first transmission assembly includes a first crank and a first connecting rod; one end of the first crank is driven by the motor, the other end of the first crank is hinged to one end of the first connecting rod, and the other end of the first connecting rod is hinged to the first driving portion of the first movable tool holder;

[0023] The second transmission assembly includes a driving cam, a second driving crank and a second connecting rod; one end of the second connecting rod is hinged to the second driving part of the second movable tool holder, the other end of the second connecting rod is hinged to one end of the second driving crank, and the second driving crank is rotatably set on the frame; the other end of the second driving crank is provided with a movable or deformable abutment portion; the driving cam is driven by the motor, and one side of the driving cam abuts against the abutment portion; when the driving cam applies force to the abutment portion from a first set direction, the abutment portion moves or deforms and offsets the transmission of the driving cam, and when the driving cam applies force to the abutment portion from a second set direction, the abutment portion links the second driving crank.

[0024] Preferably, a guide groove is provided at the lower portion of the second driving crank, and the abutting portion includes a moving rod arranged in the guide groove, and an elastic component is provided in the guide groove, and the elastic component is used to reset the moving rod; when the driving cam rotates from a first set direction and squeezes the moving rod, the moving rod retracts into the guide groove; when the driving cam rotates from a second set direction and squeezes the moving rod, the moving rod drives the second driving crank to rotate.

[0025] Preferably, when the driving cam rotates from a first setting direction, the driving cam abuts against an end portion of the moving rod, and when the driving cam rotates from a second setting direction, the driving cam abuts against a side portion of the moving rod.

[0026] A sewing machine comprises the thread trimming mechanism.

[0027] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects:

[0028] This patent uses two movable knives to cooperate in thread cutting. When one of the movable knives retreats and hooks the thread, the other movable knife advances and cooperates in thread cutting. The thread cutting completed by the two movable knives is closer to the machine needle, achieving a shorter thread end effect.

[0029] The two movable knives of this patent are both mounted on the rotary hook shaft sleeve and are coaxially arranged; the transmission is highly accurate and is also conducive to the control of the background program.

[0030] This patent can use one power source to control two movable knives separately, achieving further optimization in structure and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the assembled state of the first movable knife assembly and the second movable knife assembly of the present invention.

[0032] Figure 2 It is a schematic diagram of the disassembled state of the first movable knife assembly and the second movable knife assembly of the present invention.

[0033] Figure 3 It is a schematic diagram of the installation of the first movable knife assembly and the second movable knife assembly of the present invention.

[0034] Figure 4 It is a schematic diagram of the cooperation between the first movable knife and the second movable knife of the present invention.

[0035] Figure 5 It is one of the transmission schematic diagrams of the thread trimming mechanism of the present invention.

[0036] Figure 6 This is the second transmission schematic diagram of the thread trimming mechanism of the present invention.

[0037] Figure 7 Schematic diagram of the second drive crank of the present invention.

[0038] Figure 8 It is a schematic diagram of the thread trimming mechanism of the present invention being installed on a frame.

[0039] Figure 9 yes Figure 8 Enlarged view of point A.

[0040] Figure 10 It is a schematic diagram of the working angle of the drive assembly of the present invention.

[0041] Figure 11 It is a schematic diagram of the cooperation between the first movable knife and the second movable knife in another embodiment.

[0042] Figure 12 This is one of the transmission schematic diagrams of yet another embodiment.

[0043] Figure 13 This is the second transmission schematic diagram of yet another embodiment. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with specific embodiments:

[0045] Example 1, as Figure 1-10As shown, the double movable knife assembly of the thread trimming mechanism of the sewing machine includes a first movable knife assembly 10 and a second movable knife assembly 20; the first movable knife assembly 10 and the second movable knife assembly 20 are both rotatably sleeved on the outside of the adapted rotary hook mechanism; the first movable knife assembly is used to hook the sewing thread, and the second movable knife assembly cooperates with the first movable knife assembly to cut the sewing thread;

[0046] The first movable knife assembly 10 includes a first movable knife holder 11 and a first movable knife 12. A first ring portion 111 is provided in the middle of the first movable knife holder. The first ring portion 111 is used to be rotatably mounted on the outer side of the rotary hook mechanism 30. A first driving portion 112 is provided on one side of the first ring portion 111, and a first movable knife mounting portion 113 is provided on the other side. The first movable knife mounting portion 113 is a component extending along the axial direction of the first ring portion 111. The first movable knife 12 is mounted on the first movable knife mounting portion 113. The tip of the first movable knife is provided with a first cutting edge 121.

[0047] The second movable knife assembly 20 includes a second movable knife holder 21 and a second movable knife 22. A second ring portion 211 is provided in the middle of the second movable knife holder 21, and the second ring portion is used to be rotatably mounted on the outer side of the rotary hook mechanism. A second driving portion 212 is provided on one side of the second ring portion, and a second movable knife mounting portion 213 is provided on the other side. The second movable knife mounting portion 213 is a component extending along the axial direction of the second ring portion 211, and the second movable knife 22 is mounted on the second movable knife mounting portion 213.

[0048] The second movable blade 22 is positioned above the first movable blade 12, with its front end resting against the upper surface of the first movable blade 12. A second cutting edge 221 is provided at the front end of the second movable blade. When the second movable blade 22 slides to a set position on the surface of the first movable blade 12, the second cutting edge 221 cooperates with the first cutting edge 121 to cut the sewing thread. Specifically, the first loop portion 111 and the second loop portion 211 are both mounted on the front end of the rotary hook sleeve 301 of the rotary hook mechanism 30. A ring portion 302 is provided at the front end of the rotary hook sleeve 301. The first loop portion 111 and the second loop portion 211 are adjacently mounted on the ring portion 302.

[0049] The first movable knife 12 and the second movable knife 22 are both located on the same side of the needle position so that the first movable knife can be retracted and the second movable knife can be advanced to achieve thread cutting. During the thread cutting process, the first movable knife 12 first rotates in the first direction to a set position, and then rotates in the second direction to drive the sewing thread; when the first movable knife rotates in the second direction, the second movable knife 22 rotates in the first direction, and the second movable knife 22 slides on the surface of the first movable knife 12. The second cutting edge 221 cooperates with the first cutting edge 121 to cut the sewing thread; the first direction of rotation is counterclockwise, and the second direction of rotation is clockwise; or, the first direction of rotation is clockwise, and the second direction of rotation is counterclockwise. Preferably, a front hole groove 122 and a thread hooking groove 123 are provided on the first movable knife 12, and the front hole groove 122 and the thread hooking groove 123 are arranged along the rotation direction of the first movable knife 12; the front hole groove 122 is arranged at the tip of the first movable knife 12, and the first cutting edge 121 is provided at the front edge of the front hole groove 122; the thread hooking groove 123 is provided in the middle of the first movable knife, and an opening 1231 for hooking the thread is provided on the thread hooking groove 123; a accommodating groove 124 for accommodating sewing thread is provided between the front hole groove and the thread hooking groove.

[0050] Preferably, the first ring portion 111 and the second ring portion 211 are arranged in parallel front and back, or the first ring portion 111 and the second ring portion 211 are arranged inside and outside;

[0051] The first ring portion 111 and the second ring portion 211 are arranged on the same axis to ensure tight fit between the first movable knife and the second movable knife.

[0052] Preferably, the first drive unit 112 and the second drive unit 212 are both located on the same side; the first movable knife 12 and the second movable knife 22 are both located on the same side. If the two movable knives are both located on the same side, it is possible to achieve a coordinated thread cutting operation in which one knife moves forward and the other knife moves backward. If the two movable knives are located on different sides, only the thread cutting action at the end of sewing can be achieved, and the thread cutting action at the beginning of sewing cannot be achieved; when the two movable knives are located on different sides, the two knives move forward or backward synchronously. Even if a front hole slot 122 is provided on one of the knives, before the front hole slot 122 moves under the needle, the other movable knife will move to the needle position and will not be able to cut the thread.

[0053] Described front hole slot 122 and / or hook thread slot 123 allow the needle 90 of sewing machine to pass through. This design corresponds to the needle position of needle 90, and both positions are applicable.

[0054] The thread trimming mechanism of the sewing machine includes the double-moving knife assembly described above; and further includes:

[0055] A first transmission assembly 40, which is used to drive the first driving portion 112 of the first ring portion;

[0056] A second transmission assembly 50, which is used to drive the second driving portion 212 of the second ring portion;

[0057] At least one drive assembly 60 is used to drive the first transmission assembly 40 and / or the second transmission assembly 50. A single drive assembly 60 offers lower costs and simpler electronic control. Ideally, the first and second transmission assemblies 40 and 50 are located on opposite sides of the drive assembly. This facilitates the configuration of the transmission structure, enabling one drive assembly to swing upward for feed and the other to swing downward for retraction.

[0058] Preferably, the driving component is a motor 101, and the motor shaft of the motor drives the first transmission component 40 and the second transmission component 50; the motor can be set as a dual-axis motor, and the other end of its motor shaft is used to drive another set of mechanisms 102, such as a presser foot lifting mechanism or a needle distance adjustment mechanism, etc. The technical solution for how to share a motor between the two sets of mechanisms is relatively mature and will not be described in detail in this application.

[0059] The first transmission assembly includes a first crank 41 and a first connecting rod 42; one end of the first crank 41 is fixedly mounted on a tangent crank shaft 103, which is in transmission with the motor shaft; the other end of the first crank is hingedly connected to one end of the first connecting rod 42, and the other end of the first connecting rod is hingedly connected to the first driving portion 112 of the first movable tool holder; a first spring 48 is mounted on the first crank 41, which ensures that the first transmission assembly has a tendency to maintain its reset motion;

[0060] The second transmission assembly 50 includes an intermittent motion mechanism 59; when the first movable knife 12 rotates in the first direction, the intermittent motion mechanism 59 isolates the power transmission between the drive assembly and the second movable knife assembly 20; when the first movable knife 12 rotates in the second direction, the intermittent motion mechanism 59 transmits the power of the drive assembly to the second movable knife assembly 20. Specifically, the second transmission assembly includes a drive cam 51, a second drive crank 52, and a second connecting rod 53; the second drive crank 52 is rotatably mounted on the frame via a hinge point 521; one end of the second connecting rod 52 is hinged to the second drive portion 212 of the second movable knife frame, and the other end of the second connecting rod 53 is hinged to one end of the second drive crank 52, and the second drive crank is rotatably mounted on the frame;

[0061] The intermittent motion mechanism 59 is arranged between the second driving crank 52 and the driving cam 51; the intermittent motion mechanism 59 includes a movable or deformable abutment portion 54 arranged at the other end of the second driving crank 52; the driving cam 51 is fixedly mounted on the tangent crank shaft 103, and the driving cam 51 and the first crank 41 move synchronously; one side of the driving cam 51 abuts on the abutment portion 54; when the driving cam applies force to the abutment portion 54 from a first set direction (the first set direction of the driving cam is counterclockwise rotation, corresponding to the process of the first movable knife 12 rotating in the first direction), the abutment portion moves or deforms and offsets the transmission of the driving cam 51, and when the driving cam applies force to the abutment portion from a second set direction (the second set direction of the driving cam is clockwise rotation, corresponding to the process of the first movable knife 12 rotating in the second direction), the abutment portion 54 links the second driving crank 52. If there is no intermittent motion mechanism 59, when the first movable knife assembly moves in the first direction, the second movable knife assembly will also move in the first direction, and the second movable knife assembly will interfere with the action of the first movable knife assembly to hook the sewing thread, resulting in thread cutting failure.

[0062] Preferably, a guide slot 522 is provided at the lower portion of the second drive crank 52. The abutment portion 54 includes a movable rod 545 disposed within the guide slot 522. An elastic component 541 is disposed within the guide slot 522 to reposition the movable rod 545. When the drive cam 51 rotates from a first set direction and compresses the movable rod, the drive cam abuts against the end 544 of the movable rod, causing the movable rod 545 to retract into the guide slot 522 and isolate power transmission. When the drive cam rotates from a second set direction and compresses the movable rod 545, the drive cam abuts against the side 543 of the movable rod, causing the movable rod to rotate the second drive crank 52. An adjusting nut 542 is mounted at the rear end of the movable rod 545. Rotating the adjusting nut 542 controls the elastic force of the elastic component 541. A second shock-absorbing pad 523 is provided on one side of the second drive crank 52. The second shock-absorbing pad 523 abuts against a bracket 524, which is fixed to the frame 100. A second spring 58 is mounted on the second driving crank 52 so that the second driving crank 52 can be quickly reset after the moving rod 545 leaves the surface of the driving cam 51. The elastic force of the second spring 58 is relatively weak and does not hinder the retraction of the moving rod 545.

[0063] A sewing machine comprises the thread trimming mechanism.

[0064] The cooperation of the first movable knife and the second movable knife in this embodiment is as follows Figure 4As shown; in this embodiment, the front hole groove 122 of the first movable knife 12 is used as the needle lowering position of the needle to perform the thread cutting action in the sewing start stage; the thread hooking groove 123 of the first movable knife 12 is used to perform the thread cutting action at the end of the sewing stage.

[0065] The thread trimming method of the thread trimming mechanism at the beginning of the seam, such as Figure 9 As shown:

[0066] (1) Position a0 is the initial position of the drive assembly;

[0067] (2) The driving assembly rotates clockwise from the a0 position to the a1 position, the first movable knife 12 moves forward, and the second movable knife 22 does not move; the corresponding transmission process is: the driving assembly drives the first crank 41, the first connecting rod 42 and the first movable knife assembly 10, and the first movable knife 12 moves toward the needle direction; during this process, the front hole groove 122 of the first movable knife 12 has passed the needle position; the driving assembly simultaneously drives the driving cam 51, and the wheel surface of the driving cam 51 abuts against the end 544 of the moving rod and compresses the moving rod; at the a1 position, the driving cam has rotated past the change node, and the wheel surface of the driving cam abuts against the side 543 of the moving rod; as shown Figure 5 and 6 As shown, before the change node, the driving cam cannot drive the second crank 52 by rotating counterclockwise or clockwise. After the change node, the driving cam can drive the second crank 52 by rotating counterclockwise.

[0068] (3) The driving assembly rotates counterclockwise from position a1 to position a2, and the first movable knife 12 retreats to the front hole slot 122 below the needle; the controller then controls the needle to first pass downward through the front hole slot 122, then upwardly exit the front hole slot 122 and be lifted to a suitable position (the suitable position must ensure that the movement of the first movable knife 12 is not disturbed, and the needle is generally lifted to the top of the needle plate); at this time, the upper thread on the needle will remain in the front hole slot 122;

[0069] (4) The driving assembly rotates counterclockwise from position a2 to position a3, at which time the first movable knife 12 and the second movable knife 22 move toward each other; the front hole groove 122 of the first movable knife 12 drives the end of the face thread toward the second movable knife; the second cutting edge 221 of the second movable knife 22 slides toward the front hole groove 122; at position a3, the second cutting edge 221 cooperates with the first cutting edge 121 to cut the face thread; the corresponding transmission process is as follows: the tangent crank shaft 103 rotates counterclockwise, the first crank 41 drives the first movable knife backward; the wheel surface of the driving cam abuts against the side portion 543 of the moving rod, driving the second movable knife forward;

[0070] (5) The driving assembly rotates counterclockwise from position a3 to position a4, and the first movable knife 12 and the second movable knife 22 continue to move toward each other; at position a4, after the outermost wheel surface of the driving cam passes the side portion 543 of the moving rod, the second movable knife 22 moves to the limit position and is reset under the action of the spring;

[0071] (6) The driving assembly rotates counterclockwise from position a4 to position a0, and the first movable knife 12 also completes the reset.

[0072] The sewing thread of the thread trimming mechanism at the end of sewing stage is a twisted combination of the upper thread and the lower thread; the transmission process at the end of sewing stage is consistent with the transmission process at the start of sewing stage, so it will not be expanded in detail.

[0073] The thread trimming method of the thread trimming mechanism at the end of the sewing stage, such as Figure 9 As shown:

[0074] (1) Position a0 is the initial position of the drive assembly;

[0075] (2) The driving assembly rotates clockwise from position a0 to position a1, the first movable knife 12 moves forward, and the second movable knife 22 does not move; the thread hooking groove 123 of the first movable knife 12 is used to clamp the sewing thread;

[0076] (3) The driving assembly rotates counterclockwise from position a1 to position a3, at which point the first movable knife 12 and the second movable knife 22 move toward each other; the thread hooking groove 123 of the first movable knife 12 drives the sewing thread toward the second movable knife, and the sewing thread automatically snaps into the receiving groove and then presses against the first cutting edge 121 of the front hole groove 122; the second cutting edge 221 of the second movable knife 22 slides toward the front hole groove 122; at position a3, the second cutting edge 221 cooperates with the first cutting edge 121 to cut the sewing thread;

[0077] (4) The driving assembly rotates counterclockwise from position a3 to position a4, and the first movable knife 12 and the second movable knife 22 continue to move toward each other; at position a4, the second movable knife is reset under the action of the spring;

[0078] (5) The driving assembly rotates counterclockwise from position a4 to position a0, and the first movable knife 12 also completes the reset.

[0079] The main difference between the end of sewing stage and the start of sewing stage is the early process of the first moving knife hooking the sewing thread.

[0080] Example 2, as a new variation, Figure 11As shown, the shape of the new first movable knife 80 has been changed. The original front hole groove 122 and the thread hooking groove 123 are merged into a new joint groove 801. A second cutting edge 802 is provided on the front side of the joint groove 801, and a second thread hooking groove 803 is provided on the back side of the joint groove. The steps of the new first movable knife 80 in the sewing starting stage and the sewing ending stage are the same; Figure 9 At position a1, the joint groove 801 of the new first movable knife 80 allows the needle to insert the needle and complete the upper thread hooking at the beginning of the seam. The second thread hooking groove 803 of the joint groove 801 completes the sewing thread hooking at the end of the sewing. From position a1, the machine moves directly to position a3 for thread trimming, and the subsequent steps remain unchanged.

[0081] Embodiment 3: This embodiment is basically the same as embodiment 1, except that the transmission structure is different, specifically, the structures of the first transmission assembly and the second transmission assembly are different.

[0082] The first transmission assembly 40 includes a third crank 61, a slider 66, a chute 62, a first transmission shaft 63, a fourth crank 64, and a third connecting rod 65. The third crank 61 is fixed to the motor shaft. A slider 66 is hingedly connected to the swinging end of the third crank 61. The slider 66 is disposed within a sliding groove 621 of the chute 62, which is fixed to the first transmission shaft 63. The swinging of the third crank 61 drives the first transmission shaft 63 to swing. The fourth crank 64 is fixed to the other end of the first transmission shaft 63, and the first movable blade assembly 10 is driven by the third connecting rod 65. The combination of the slider 66 and the chute 62 allows the third crank to rotate 360 ​​degrees without hindrance. That is, the motor can rotate 360 ​​degrees. During one rotation of the motor, the first movable blade advances and retreats. The angular range corresponding to the retreat of the first movable blade is then allocated to the second transmission assembly, and the second movable blade advances within this angular range, completing the thread trimming operation.

[0083] The second transmission assembly 50 includes a second drive cam 71, a fifth crank 72, a second transmission shaft 73, a sixth crank 74 and a fourth connecting rod 75; the second drive cam and the fifth crank constitute the intermittent motion mechanism 59; the second drive cam is provided with a working curved surface 711 and a non-working curved surface 712, the working curved surface transmits power to the fifth crank 72, and the non-working curved surface isolates the power transmission between the second drive cam and the fifth crank. A roller 721 is installed at the swinging end of the fifth crank 72. The fifth crank is fixed on the second transmission shaft 73, and the second transmission shaft directly or indirectly transmits power to the second movable knife assembly. This design ensures that when the first transmission assembly is working, there is an angle range within which the second transmission assembly is not actually working, thereby achieving the technical purpose of the second movable knife not moving when the first movable knife moves forward.

[0084] The first transmission shaft 63 is a hollow sleeve, and the second transmission shaft 73 is a core rod; the second transmission shaft 73 is inserted into the first transmission shaft 63, and the two are concentrically arranged. This design simplifies the transmission structure and is conducive to the precision of the transmission.

[0085] It should be noted that the structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantial technical significance. Any modification of the structure, change in the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose of the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0086] It should also be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or indirectly connected to the other element through an intervening element.

[0087] In addition, the descriptions of "first", "second", etc. in this application are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

Claims

1. The double-moving knife assembly of the thread trimming mechanism of the sewing machine is characterized by: The invention comprises a first movable knife assembly (10) and a second movable knife assembly (20); the first movable knife assembly (10) and the second movable knife assembly (20) are both rotatably sleeved on the outside of an adapted rotary hook mechanism; the first movable knife assembly is used to hook the sewing thread, and the second movable knife assembly cooperates with the first movable knife assembly to cut the sewing thread; The first movable knife assembly (10) comprises a first movable knife holder (11) and a first movable knife (12); a first cutting edge (121) is provided at the tip of the first movable knife; The second movable knife assembly (20) comprises a second movable knife holder (21) and a second movable knife (22); The second movable knife (22) is arranged above the first movable knife (12), the front end of the second movable knife (22) is in contact with the upper surface of the first movable knife (12), and the front end of the second movable knife is provided with a second cutting edge (221); The first movable knife (12) and the second movable knife (22) are both located on the same side of the needle position; during the thread cutting process, the first movable knife (12) first rotates in the first direction to a set position, and then rotates in the second direction and drives the sewing thread; when the first movable knife rotates in the second direction, the second movable knife (22) rotates in the first direction, and the second movable knife (22) slides on the surface of the first movable knife (12), and the second cutting edge (221) cooperates with the first cutting edge (121) to cut the sewing thread; The first direction of rotation is counterclockwise rotation, and the second direction of rotation is clockwise rotation; or, the first direction of rotation is clockwise rotation, and the second direction of rotation is counterclockwise rotation.

2. The double movable knife assembly of the thread trimming mechanism of a sewing machine according to claim 1, characterized in that: A first ring portion (111) is provided in the middle of the first movable knife holder, and the first ring portion (111) is used to be rotatably mounted on the outer side of the rotary hook mechanism (30); a first driving portion (112) and the first movable knife (12) are provided on the first ring portion (111); A second ring portion (211) is provided in the middle of the second movable knife holder (21), and the second ring portion is used to be rotatably mounted on the outside of the rotary hook mechanism; a second driving portion (212) and the second movable knife (22) are provided on the second ring portion; The first movable knife (12) is provided with a front hole groove (122) and a thread hooking groove (123), and the front hole groove (122) and the thread hooking groove (123) are arranged along the rotation direction of the first movable knife (12); the front hole groove (122) is provided at the tip of the first movable knife (12), and the first cutting edge (121) is provided at the front edge of the front hole groove (122); the thread hooking groove (123) is provided at the middle of the first movable knife, and an opening (1231) for hooking the thread is provided on the thread hooking groove (123); and a receiving groove (124) for receiving the sewing thread is provided between the front hole groove and the thread hooking groove; The front hole slot (122) and / or the thread hook slot (123) allow a needle of a sewing machine to pass through.

3. The double movable knife assembly of the thread trimming mechanism of a sewing machine according to claim 2, characterized in that: The first ring portion (111) and the second ring portion (211) are arranged in parallel front and back, or the first ring portion (111) and the second ring portion (211) are arranged in a sleeved arrangement inside and outside; The first ring portion (111) and the second ring portion (211) are arranged on the same axis.

4. The thread trimming mechanism of the sewing machine is characterized by: The double-movable knife assembly comprises the double-movable knife assembly according to any one of claims 1 to 3; and further comprises: a first transmission assembly (40), configured to drive the first movable knife assembly (10); a second transmission assembly (50), which is used to drive the second movable knife assembly (20); A driving assembly, used for driving the first transmission assembly (40) and the second transmission assembly (50); The second transmission assembly (50) includes an intermittent motion mechanism (59); when the first movable knife (12) rotates in a first direction, the intermittent motion mechanism (59) isolates the power transmission between the drive assembly and the second movable knife assembly (20); when the first movable knife (12) rotates in a second direction, the intermittent motion mechanism (59) transmits the power of the drive assembly to the second movable knife assembly (20).

5. The thread trimming mechanism of a sewing machine according to claim 4, characterized in that: The first transmission assembly includes a first crank (41) and a first connecting rod (42); one end of the first crank (41) is driven by the motor, the other end of the first crank is hinged to one end of the first connecting rod (42), and the other end of the first connecting rod is hinged to the first driving portion (112) of the first movable tool holder; The second transmission assembly comprises a driving cam (51), a second driving crank (52) and a second connecting rod (53); one end of the second connecting rod (52) is hinged to the second driving portion (212) of the second movable tool holder, and the other end of the second connecting rod (53) is hinged to one end of the second driving crank (52), and the second driving crank is rotatably arranged on the frame; the driving cam (51) is driven by the motor; The intermittent motion mechanism (59) is provided between the second driving crank (52) and the driving cam (51); the intermittent motion mechanism (59) includes a movable or deformable abutting portion (54); the abutting portion (54) is provided at one end of the second driving crank (52), and one side of the driving cam (51) abuts against the abutting portion (54); when the first movable knife (12) rotates in the first direction, the abutting portion moves or deforms and offsets the transmission of the driving cam (51); when the first movable knife (12) rotates in the second direction, the abutting portion (54) transmits power to the second driving crank (52).

6. The thread trimming mechanism of a sewing machine according to claim 5, characterized in that: A guide groove (522) is provided at the lower portion of the second driving crank (52), and the abutting portion (54) includes a moving rod (545) arranged in the guide groove (522), and an elastic component (541) is provided in the guide groove (522), and the elastic component (541) is used for resetting the moving rod (545); when the driving cam (51) applies force to the end (544) of the moving rod, the moving rod (545) retracts into the guide groove (522) and isolates power transmission; when the driving cam abuts against the side (543) of the moving rod, the driving cam drives the second driving crank (52) through the moving rod.

7. The thread trimming mechanism of a sewing machine according to claim 4, characterized in that: The first transmission assembly (40) includes a third crank (61), a slider (66), a slide member (62) and a first transmission shaft (63); the third crank (61) is fixed on the motor shaft, the swing end of the third crank (61) is hinged with a slider (66), the slider (66) is arranged in a sliding groove (621) of the slide member (62), and the slide member (62) is fixed on the first transmission shaft (63); the swing of the third crank (61) drives the first transmission shaft (63) to swing; the other end of the first transmission shaft (63) directly or indirectly drives the first movable knife assembly (10).

8. The thread trimming mechanism of a sewing machine according to claim 7, characterized in that: The second transmission assembly (50) includes a second driving cam (71), a fifth crank (72) and a second transmission shaft (73); the second driving cam and the fifth crank constitute the intermittent motion mechanism (59); a working curved surface (711) and a non-working curved surface (712) are provided on the second driving cam, the working curved surface transmits power to the fifth crank (72), and the non-working curved surface isolates the power transmission between the second driving cam and the fifth crank; the fifth crank is fixed on the second transmission shaft (73), and the second transmission shaft directly or indirectly transmits power to the second movable knife assembly.

9. The thread trimming mechanism of a sewing machine according to claim 8, characterized in that: The first transmission shaft (63) is a hollow shaft sleeve, and the second transmission shaft (73) is a core rod; the second transmission shaft (73) is inserted into the first transmission shaft (63), and the two are concentrically arranged.

10. A sewing machine, characterized in that: The invention comprises the thread cutting mechanism according to any one of claims 4 to 9.

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