Thread trimming method of sewing machine with double movable cutter assemblies

Abstract

The invention belongs to the technical field of sewing machines, and particularly relates to a thread trimming method of a sewing machine with a double-moving-cutter assembly, and the method comprises the following steps: S1, a first moving cutter and a second moving cutter are located on the same side of a needle position; s2, the first movable cutter moves towards the machine needle, and the front hole groove reaches a first set position a1; s3, the driving assembly drives the first movable cutter to retreat and drives the second movable cutter to advance; the first moving cutter and the second moving cutter move in opposite directions; s4, when the front hole groove passes through a second set position a2, the machine needle executes the needle feeding action of the first needle in the sewing starting stage; S5, the driving assembly drives the first movable cutter to continuously return, the second movable cutter continuously advances, and the sewing thread located in the front hole groove is cut off; s6, resetting the first moving cutter and the second moving cutter; s7, continuing sewing; s8, executing thread trimming at the sewing ending stage; 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 method of a sewing machine with a double movable knife assembly. 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, a double-knife assembly and a thread trimming method, which can achieve shorter thread ends when trimming threads.

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

[0008] A thread trimming method for a sewing machine with a double movable knife assembly, the sewing machine comprising a thread trimming mechanism, the thread trimming mechanism comprising a first movable knife assembly, a second movable knife assembly, and a drive assembly; the first movable knife assembly and the second movable knife assembly are both rotatably sleeved on the outside of an adapted rotary hook mechanism; the drive assembly drives the first movable knife assembly and the second movable knife assembly;

[0009] The first movable knife assembly includes a first movable knife, and the first movable knife is provided with a front hole groove and a wire hooking groove; the front hole groove and the wire hooking groove are arranged along the rotation direction of the first movable knife;

[0010] The front hole groove is provided at the tip of the first movable knife, and is used for the needle to pass through and to hook the sewing thread at the sewing stage;

[0011] The thread hooking groove is arranged at the rear side of the front hole groove, and the thread hooking groove is provided with a thread hooking opening, and the opening is used to hook the sewing thread into the thread hooking groove at the end of the sewing stage; an accommodating groove for accommodating the sewing thread is provided between the front hole groove and the thread hooking groove, or the thread hooking groove is connected to the front hole groove as a whole;

[0012] The second movable knife assembly includes a second movable knife, which abuts against the surface of the first movable knife during rotation; the front edge of the front hole groove is provided with a first cutting edge, and the front end of the second movable knife is provided with a second cutting edge; the first cutting edge and the second cutting edge cooperate to cut the sewing thread;

[0013] The thread trimming method includes thread trimming at the beginning of sewing and thread trimming at the end of sewing, and the steps are as follows:

[0014] S1, in the initial state of thread trimming at the start of sewing, the first movable knife and the second movable knife are both located on the same side of the needle position;

[0015] S2. The driving assembly drives the first movable knife to move toward the needle. The front hole slot first passes through the second set position a2 and then reaches the first set position a1. The second set position a2 is located directly below the needle position. When the front hole slot stays at the first set position a1, the thread hooking slot is located at the second set position a2.

[0016] S3, the driving assembly drives the first movable knife to retract and the second movable knife to advance; the first movable knife and the second movable knife move toward each other and approach each other; during the retraction of the first movable knife, the front hole slot passes through the second set position a2 for the second time;

[0017] S4. When the front hole slot passes the second set position a2, the driving assembly suspends the movement of the first movable knife and the second movable knife; the needle performs the first stitch movement of the sewing start phase: the needle first passes downward through the front hole slot, then upward out of the front hole slot and is lifted to a suitable position; the sewing thread on the needle remains in the front hole slot of the first movable knife;

[0018] S5. The driving assembly drives the first movable knife to continue to retract, and the second movable knife to continue to advance; the second movable knife slides on the surface of the first movable knife; the front hole groove of the first movable knife brings the sewing thread close to the second cutting edge; the first cutting edge and the second cutting edge approach each other and cut the sewing thread in the front hole groove when they overlap;

[0019] S6: Thread trimming is completed at the seam start stage; the driving assembly drives the first and second movable knives to reset;

[0020] S7, continue sewing until the sewing is completed;

[0021] S8, executing the thread trimming to end the sewing stage, the driving assembly drives the first movable knife to move toward the needle. When the front hole slot reaches the first set position a1, the thread hooking slot is located at the second set position a2, and the opening of the thread hooking slot faces the sewing thread; the second movable knife remains stationary;

[0022] S9, the thread hooking groove of the first movable knife completes the thread hooking action of the sewing thread;

[0023] S10, the driving assembly drives the first movable knife to retract and the second movable knife to advance; the first movable knife and the second movable knife move toward each other and approach each other; the second movable knife slides on the surface of the first movable knife; the sewing thread in the thread hooking groove enters the front hole groove, and the first cutting edge and the second cutting edge cooperate to cut the sewing thread in the front hole groove;

[0024] S11, the driving assembly drives the first movable knife and the second movable knife to reset, and the thread trimming in the sewing stage is completed.

[0025] Preferably, step S4 is executed in step S2: when the front hole slot passes through the second set position a2 for the first time, step S4 is executed first, and then the first movable knife is continued to be moved so that the front hole slot moves to the first set position a1; during the retreat of the first movable knife, when the front hole slot passes through the second set position a2 for the second time, S5 is directly executed.

[0026] Preferably, the first movable knife assembly includes a first movable knife holder and the 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 sleeved on the outer side of the rotary hook mechanism; a first driving portion and the first movable knife are provided on the first ring portion;

[0027] The second movable knife assembly includes a second movable knife holder and the 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 rotate and fit on the outside of the rotary hook mechanism; a second driving portion and the second movable knife are provided on the second ring portion.

[0028] 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;

[0029] The first ring portion and the second ring portion are arranged on the same axis.

[0030] Preferably, the thread cutting mechanism further comprises:

[0031] a first transmission assembly, configured to drive the first movable knife assembly;

[0032] a second transmission assembly, configured to drive the second movable knife assembly;

[0033] The driving assembly is used to drive the first transmission assembly and the second transmission assembly;

[0034] The second transmission assembly includes an intermittent motion mechanism; during the process of the first movable knife rotating from the initial position to the first set position a1, the intermittent motion mechanism isolates the power transmission between the drive assembly and the second movable knife assembly; during the process of the first movable knife rotating from the first set position a1 to the initial position, the intermittent motion mechanism transmits the power of the drive assembly to the second movable knife assembly.

[0035] Preferably, the first transmission assembly includes a first crank and a first connecting rod; one end of the first crank is driven by the driving assembly, 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;

[0036] 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 portion of the second movable tool holder, and 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 mounted on the frame; the driving cam is driven by the driving assembly;

[0037] The intermittent motion mechanism is arranged between the second driving crank and the driving cam; the intermittent motion mechanism includes a movable or deformable abutment portion; the abutment portion is arranged at one end of the second driving crank, and one side of the driving cam abuts against the abutment portion; in the process of the first movable knife rotating from the initial position to the first set position a1, the abutment portion moves or deforms and offsets the transmission of the driving cam, and in the process of the first movable knife rotating from the first set position a1 to the initial position, the abutment portion transmits power to the second driving crank.

[0038] 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 applies force to the end of the moving rod, the moving rod retracts into the guide groove and isolates the power transmission; when the driving cam abuts against the side of the moving rod, the driving cam drives the second driving crank through the moving rod; when the first movable knife rotates from the initial position to the first set position a1, the wheel surface of the driving cam 51 passes over the end of the moving rod.

[0039] Preferably, the first transmission assembly includes a third crank, a slider, a slide member and a first transmission shaft; the third crank is fixed on the motor shaft of the driving assembly, the swinging end of the third crank is hinged with a slider, the slider is arranged in the sliding groove of the slide member, and the slide member is fixed on the first transmission shaft; the swinging of the third crank drives the first transmission shaft to rotate; the other end of the first transmission shaft directly or indirectly drives the first movable knife assembly.

[0040] Preferably, the second transmission assembly includes a second driving cam, a fifth crank and a second transmission shaft; the second driving cam and the fifth crank constitute the intermittent motion mechanism; the second driving cam is provided with a working curved surface and a non-working curved surface, the working curved surface transmits power to the fifth crank, 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, and the second transmission shaft directly or indirectly transmits power to the second movable knife assembly; the first transmission shaft is a hollow sleeve, and the second transmission shaft is a core rod; the second transmission shaft is inserted into the first transmission shaft, and the two are concentrically arranged.

[0041] Preferably, the end of the second transmission shaft extends out of the first transmission shaft and is mounted with a sixth crank 74, the swing end of the sixth crank is hinged to a fourth connecting rod, and the other end of the fourth connecting rod is hinged to the second driving portion of the second ring portion;

[0042] A fourth crank is installed at the end of the first transmission shaft, and a third connecting rod is hinged to the swing end of the fourth crank; the other end of the third connecting rod is hinged to the first driving part of the first ring part.

[0043] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects:

[0044] This patent uses two movable knives to cooperate in thread cutting. When the first movable knife retreats and hooks the thread, the second movable knife moves forward 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.

[0045] In the process of thread trimming at the beginning of sewing and at the end of sewing, the patent has an additional step of the first movable knife pausing and the step of the needle passing through the front hole slot in the beginning of sewing; and an additional action of the thread hooking slot hooking the sewing thread in the end of sewing. In fact, in the process of thread trimming at the beginning of sewing and at the end of sewing, the motion trajectories of the first movable knife and the second movable knife are the same, which greatly simplifies the control of the sewing machine program and streamlines the transmission structure of the thread trimming mechanism.

[0046] 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.

[0047] This patent can use a single power source to control two movable knives separately, achieving further optimization in terms of structure and cost. In addition, under reasonable design, it is possible to add functions such as automatic presser foot lifting on the basis of the technical solution of this patent, and allocate part of the idle rotation space of the drive component to the presser foot lifting mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] 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.

[0049] 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.

[0050] 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.

[0051] Figure 4 It is a schematic diagram of the cooperation between the first movable knife and the second movable knife of the present invention.

[0052] Figure 5 It is one of the transmission schematic diagrams of the thread trimming mechanism of the present invention.

[0053] Figure 6 This is the second transmission schematic diagram of the thread trimming mechanism of the present invention.

[0054] Figure 7 Schematic diagram of the second drive crank of the present invention.

[0055] Figure 8 It is a schematic diagram of the thread trimming mechanism of the present invention being installed on a frame.

[0056] Figure 9 yes Figure 7 Enlarged view of point A.

[0057] Figure 10 It is a schematic diagram of the working angle of the drive assembly of the present invention.

[0058] Figure 11 It is a schematic diagram of the cooperation between the first movable knife and the second movable knife in another embodiment.

[0059] Figure 12 This is one of the transmission schematic diagrams of yet another embodiment.

[0060] Figure 13 This is the second transmission schematic diagram of yet another embodiment. DETAILED DESCRIPTION

[0061] The present invention will be further described below in conjunction with specific embodiments:

[0062] Example 1, as Figure 1-10 As 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;

[0063] 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.

[0064] 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 rotate and fit on the outside of the rotary hook mechanism 30; 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 axially along the second ring portion 211, and the second movable knife 22 is mounted on the second movable knife mounting portion 213; specifically, the first ring portion 111 and the second ring portion 211 are both fitted on the front end of the rotary hook sleeve 301 of the rotary hook mechanism 30, and a ring portion 302 is provided at the front end of the rotary hook sleeve 301, and the first ring portion 111 and the second ring portion 211 are adjacently fitted on the ring portion 302.

[0065] Preferably, the first ring portion 111 and the second ring portion 211 are arranged side by side front to back, or the first ring portion 111 and the second ring portion 211 are arranged inside and outside; the first ring portion 111 and the second ring portion 211 are arranged on the same axis to ensure the tightness of the fit between the first movable knife and the second movable knife.

[0066] The first movable knife 12 and the second movable knife 22 must be located on the same side of the needle position to achieve thread cutting during the process of the first movable knife retracting and the second movable knife advancing. If the first movable knife 12 and the second movable knife 22 are located on different sides of the needle position, both knives must move toward the needle position at the same time to achieve thread cutting, which is only suitable for thread cutting at the end stage.

[0067] In the actual technical solution, the mirror-image thread trimming mechanism can adjust the rotation direction of the first and second movable blades; therefore, in the present application, the first movable blade 12 and the second movable blade 22 can rotate in the first direction or in the second direction; the first direction and the second direction are two opposite directions; if the first direction is counterclockwise, the second direction is clockwise; or, if the first direction is clockwise, the second direction is counterclockwise. During the thread trimming process, the first movable blade 12 first rotates in the first direction to the first set position a1, then rotates in the second direction to return to the initial position and drive the sewing thread; when the first movable blade rotates in the second direction, the second movable blade 22 rotates in the first direction.

[0068] Preferably, 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 front hole groove 122 is used for the needle to pass through and to hook the sewing thread in the sewing stage; 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 ... The groove 123 is provided with an opening 1231 for hooking the thread, and the opening 1231 is used to hook the sewing thread into the hooking groove 123 at the end of the sewing stage; since the first cutting edge is provided at the edge of the front hole groove 122, it is necessary to guide the sewing thread in the hooking groove to the position of the front hole groove 122; in this solution, a receiving groove 124 for accommodating the sewing thread is provided between the front hole groove and the hooking groove, and the sewing thread is guided to the front hole groove 122 through the receiving groove 124; or, as Figure 11 In a new variation shown in FIG, the shape of the first movable blade 80 has been changed. The original front hole slot 122 and thread hooking slot 123 have been merged into a new combined slot 801. A second cutting edge 802 is provided on the front side of the combined slot 801, and a second thread hooking opening 803 is provided on the back side of the combined slot. The combined slot 801 allows the needle to insert the needle and complete the upper thread hooking at the beginning of the seam, while the second thread hooking opening 803 completes the sewing thread hooking at the end of the sewing process.

[0069] The second movable knife 22 is arranged above the first movable knife 12, and the front end of the second movable knife 22 is pressed against the upper surface of the first movable knife 12 and slides; the front end of the second movable knife is provided with a second cutting edge 221; when the first movable knife and the second movable knife approach each other, the front hole groove 122 or the thread hook groove 123 will bring the sewing thread to the second cutting edge, and the sewing thread will not be subjected to pressure on the first cutting edge and will not be cut until the second cutting edge coincides with the first cutting edge, and the sewing thread is cut.

[0070] The present application also seeks to protect a thread trimming mechanism for a sewing machine, comprising the double-movable knife assembly described above; and further comprising:

[0071] A first transmission assembly 40, which is used to drive the first driving portion 112 of the first ring portion;

[0072] A second transmission assembly 50, which is used to drive the second driving portion 212 of the second ring portion;

[0073] The drive assembly 60 is used to drive the first transmission assembly 40 and the second transmission assembly 50. The drive assembly 60 can be set as one or two. If one drive assembly 60 is used to drive the first transmission assembly 40 and the second transmission assembly 50, the solution cost is low but the requirements for the transmission structure and electronic control are high; if two drive assemblies 60 are used to drive the first transmission assembly 40 and the second transmission assembly 50 respectively, the transmission structure is simple and the electronic control is also simple, but the space occupied is large and the cost is high. As an ordinary technician in this field, it should be easy to realize that the two drive assemblies 60 drive the first transmission assembly 40 and the second transmission assembly 50 respectively, so it is not described in detail. It is a better choice that the first transmission assembly 40 and the second transmission assembly 50 are respectively located on two different sides of the drive assembly. The transmission structure can be set more conveniently to realize one upward swing to feed the knife and the other downward swing to retract the knife.

[0074] 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. The technical solution for how to share a motor between the two sets of mechanisms is relatively mature, so it will not be described in detail.

[0075] 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;

[0076] The second transmission assembly 50 includes an intermittent motion mechanism 59; when the first movable knife 12 rotates in the first direction, the first movable knife 12 rotates from the initial position to the first set position a1; 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 first movable knife 12 rotates from the first set position a1 to the initial position, and 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 set on the frame;

[0077] 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 against the abutment portion 54; in the process of the first movable knife 12 rotating from the initial position to the first set position a1, the driving cam rotates counterclockwise and applies pressure to the end direction of the abutment portion 54, and the abutment portion moves or deforms and offsets the transmission of the driving cam 51; in the process of the first movable knife 12 rotating from the first set position a1 to the initial position, the driving cam rotates clockwise and applies pressure to the side direction of the abutment portion, and the abutment portion 54 is driven and further drives 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.

[0078] 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 provided within the guide slot 522 for resetting the movable rod 545. When the drive cam 51 abuts against the end of the movable rod and squeezes the movable rod from the end of the movable rod, the movable rod 545 retracts into the guide slot 522 and isolates power transmission. When the first movable blade 12 rotates from the initial position to the first set position a1, the wheel surface of the drive cam 51 passes over the end 544 of the movable rod. When the drive cam abuts against the side 543 of the movable rod and squeezes the movable rod 545 from the side of the movable rod 545, the movable rod drives the second drive crank 52 to rotate. An adjusting nut 542 is installed at the rear end of the movable rod 545. The elastic force of the elastic component 541 can be controlled by rotating the adjusting nut 542. 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 drive crank 52 to ensure that the second drive crank 52 quickly returns to its original position after the movable rod 545 disengages from the surface of the drive cam 51. The elastic force of the second spring 58 is relatively weak and does not hinder the retraction of the movable rod 545.

[0079] Example 2, as Figure 12-13 As shown, this embodiment is substantially the same as the first embodiment, differing in the transmission structure, specifically: the first transmission assembly 40 includes a third crank 61, a slider 66, a slide member 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, the swinging end of the third crank 61 is hingedly connected to a slider 66, which is disposed in a sliding groove 621 of the slide member 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 other end of the first transmission shaft 63 is fixed to the fourth crank, and the swinging end of the fourth crank 64 is hingedly connected to the third connecting rod 65; the other end of the third connecting rod 65 is hingedly connected to the first driving portion 112 of the first ring portion 111. The cooperation between the slider 66 and the slide member 62 allows the third crank to rotate 360° unimpeded. That is, the motor can rotate 360°. During one rotation of the motor, the first movable knife moves forward and backward. The angle area corresponding to the retreat of the first movable knife is allocated to the second transmission component, and the second movable knife moves forward in this angle area to complete the thread cutting action.

[0080] 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, while the non-working curved surface isolates the power transmission between the second drive cam and the fifth crank. A roller 721 is mounted on the swinging end of the fifth crank 72. The fifth crank is fixed to the second transmission shaft 73. The end of the second transmission shaft 73 extends beyond the first transmission shaft 63 and is mounted with the sixth crank 74. The swinging end of the sixth crank 74 is hingedly connected to the fourth connecting rod 75. The other end of the fourth connecting rod 75 is hingedly connected to the second drive portion 212 of the second ring portion. This design ensures that when the first transmission assembly is operating, the second transmission assembly is not actually operating within an angular range, achieving the technical purpose of keeping the second movable blade stationary while the first movable blade advances.

[0081] 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.

[0082] The present application also seeks protection for a sewing machine comprising the thread trimming mechanism.

[0083] The present application also seeks to protect a thread trimming method for a sewing machine having a double-moving knife assembly, the method being implemented by the double-moving knife assembly; the thread trimming method comprising thread trimming at the start of sewing and thread trimming at the end of sewing, the steps of which are as follows:

[0084] S1, in the initial state of thread trimming at the beginning of sewing, the first movable knife 12 and the second movable knife 22 are both located on the same side of the needle position; Figure 10 As shown, position a0 is the initial position of the first movable knife 12 and the second movable knife 22; the initial positions of the first movable knife 12 and the second movable knife 22 can be slightly staggered and are not required to be at the same position;

[0085] S2, the driving assembly drives the first movable knife 12 to move toward the needle 90, such as Figure 10 As shown, the front hole slot 122 first passes through the second setting position a2, and then reaches the first setting position a1; the second setting position a2 is located directly below the needle position; when the front hole slot 122 of the first movable knife 12 is at the first setting position a1, the thread hooking slot 123 is at the second setting position a2; corresponding to the attached Figure 6In the state shown in FIG, when the front hole slot 122 is at position a1, the driving cam has rotated past the change node, and the wheel surface of the driving cam abuts against the side portion 543 of the moving rod; before the change node, the driving cam cannot drive the second movable knife whether it rotates counterclockwise or clockwise. After the change node, the driving cam can drive the second movable knife by rotating counterclockwise. Figure 6 The transmission structure shown occupies less rotation area of ​​the drive assembly, and the excess rotation area can be allocated to other presser foot lifting mechanisms or needle distance adjustment mechanisms;

[0086] S3, the driving assembly drives the first movable knife 12 to retract and the second movable knife to advance; the first movable knife and the second movable knife move toward each other and approach each other; during the retraction of the first movable knife 12, the front hole slot 122 passes through the second set position a2 for the second time; in step S3, the second movable knife starts from position a0 and advances toward the needle position, and the movement speed of the second movable knife is faster than the movement speed of the first movable knife;

[0087] S4. When the front hole slot 122 passes the second set position a2, the driving assembly suspends the action of the first movable knife 12 and the second movable knife; the thread passing through the needle 90 of the sewing machine 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 needle to perform the first needle down-stitching action in the sewing stage: the needle first passes downward through the needle plate 91 and the fabric, and then passes downward through the front hole slot 122 and enters the rotary shuttle mechanism 30 to hook the lower thread, and then the needle exits the front hole slot 122 upward and is lifted to a suitable position above the needle plate; the thread take-up rod of the sewing machine takes up the thread upward and drives the upper thread on the needle to retreat, and the upper thread is stored in the process of the thread take-up rod taking up the thread upward; the thread end of the sewing thread on the needle remains in the front hole slot 122; the sewing machine is equipped with an electronic thread clamp, which is a conventional technology Technology, such as the patent CN201520601336.3, shows an electronic thread clamp and automatic tension adjustment system of a sewing machine; in the process of the needle moving upward, the thread take-up rod of the sewing machine also synchronously takes up the thread, the electronic thread clamp locks the upper thread and stops supplying the upper thread to the needle, and the upper thread is pulled back from the needle hole of the needle by the action of the thread take-up rod to a certain length. The thread take-up mechanism of the sewing machine completes the upper thread reserve when the needle passes through the fabric for the second time, and the part of the upper thread that exceeds the required length will be cut off in step S5; the sewing action of the needle passing through the fabric for the second time is the formal sewing work; in the process of the needle passing through the front hole slot 122 for the first time and then being lifted up, the bottom thread in the rotary hook mechanism may be brought upward into the front hole slot 122, and the thread end of the bottom thread is also cut off in step S5;

[0088] S5, the driving assembly drives the first movable knife 12 to continue to retreat, and the second movable knife continues to advance; the second movable knife 22 slides on the surface of the first movable knife 12; the front hole groove 122 of the first movable knife 12 approaches the second cutting edge 221 with the sewing thread; the first cutting edge 121 and the second cutting edge 221 approach each other and Figure 10 The position a3 in the drawing is overlapped, and the sewing thread in the front hole groove 122 is cut off; this action ensures that the thread head of the upper thread on the needle meets the required length during the sewing stage;

[0089] S6, the thread trimming is completed at the seam start stage; the driving assembly drives the first movable knife 12 and the second movable knife to reset; in order to prepare a certain margin, the first movable knife 12 moves to Figure 10 The second movable knife will also move a short distance toward the position of a2 and then reset;

[0090] S7. During the previous steps S1 and S6, the presser foot of the sewing machine is pressed tightly against the fabric, and the fabric does not move. After the thread trimming is completed at the seam start stage, actual sewing is performed. Since the fabric does not move, the position where the needle penetrates the fabric for the second time is the same as the position where the needle penetrated the fabric for the first time. The needle penetrates the fabric for the second time to perform the actual sewing action until the sewing is completed. During the actual sewing process, the electronic thread clamp works normally.

[0091] S8, execute the thread trimming to end the sewing stage, the driving assembly drives the first movable knife 12 to move toward the needle direction, such as Figure 10 As shown in FIG, the front hole slot 122 reaches the first set position a1, the thread hooking slot 123 reaches the second set position a2, and the opening 1231 of the thread hooking slot 123 faces the sewing thread, which is a twisted upper thread and a lower thread; the second movable knife 22 remains stationary;

[0092] S9. The thread hooking groove 123 of the first movable knife 12 completes the thread hooking action of the sewing thread. In order to facilitate the sewing thread to enter the opening 1231 of the thread hooking groove 123, a suction device or an air blowing device can be installed at a suitable position of the sewing machine frame to guide the sewing thread into the opening 1231 through airflow.

[0093] S10. The driving assembly drives the first movable knife 12 to retract and the second movable knife to advance; the first movable knife and the second movable knife move toward each other and approach each other; the second movable knife 22 slides on the surface of the first movable knife 12; the sewing thread in the thread hooking groove 123 enters the front hole groove 122, and the first cutting edge 121 cooperates with the second cutting edge 221 to cut the sewing thread in the front hole groove 122;

[0094] S11, the driving assembly drives the first movable knife 12 and the second movable knife to reset, and the thread trimming in the sewing stage is completed.

[0095] Preferably, step S4 is executed in step S2: when the front hole slot 122 is at the second setting position a2 for the first time, step S4 is executed first, and then the front hole slot 122 of the first movable knife 12 is continued to be moved to the first setting position a1; when the front hole slot 122 passes the second setting position a2 for the second time, step S5 is directly executed.

[0096] 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.

[0097] 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.

[0098] 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. A thread trimming method for a sewing machine having a double-moving knife assembly, characterized in that: The sewing machine comprises a thread trimming mechanism, which comprises a first movable knife assembly (10), a second movable knife assembly (20) and a driving assembly; 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 driving assembly drives the first movable knife assembly (10) and the second movable knife assembly (20); The first movable knife assembly comprises a first movable knife (12), and the first movable knife (12) is provided with a front hole groove (122) and a line hooking groove (123); the front hole groove (122) and the line 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 front hole groove (122) is used for the needle to pass through and to hook the sewing thread in the sewing stage; The thread hooking groove (123) is arranged at the rear side of the front hole groove (122); the thread hooking groove (123) is provided with a thread hooking opening (1231); the opening (1231) is used to hook the sewing thread into the thread hooking groove (123) at the end of the sewing stage; an accommodating groove for accommodating the sewing thread is provided between the front hole groove (122) and the thread hooking groove (123), or the thread hooking groove (123) and the front hole groove (122) are connected as a whole; The second movable knife assembly comprises a second movable knife (22), which abuts against the surface of the first movable knife (12) during rotation; a first cutting edge (121) is provided on the front side edge of the front hole slot (122), and a second cutting edge (221) is provided at the front end of the second movable knife (22); the first cutting edge (121) and the second cutting edge (221) cooperate to cut the sewing thread; The thread trimming method includes thread trimming at the beginning of sewing and thread trimming at the end of sewing, and the steps are as follows: S1, in the initial state of thread trimming at the seam-starting stage, the first movable knife (12) and the second movable knife (22) are both located on the same side of the needle position; S2, the driving assembly drives the first movable knife (12) to move toward the needle, and the front hole groove (122) of the first movable knife first passes through the second setting position (a2) and then reaches the first setting position (a1); when the front hole groove (122) of the first movable knife is at the first setting position (a1), the thread hooking groove (123) is at the second setting position (a2), and the second setting position (a2) is located directly below the needle position; S3, the driving assembly drives the first movable knife (12) to retract and the second movable knife to advance; the first movable knife and the second movable knife move toward each other and approach each other; during the retraction of the first movable knife (12), the front hole slot (122) passes through the second set position (a2) for the second time; S4, when the front hole slot (122) passes the second set position (a2), the driving assembly suspends the movement of the first movable knife (12) and the second movable knife (22); the machine needle performs the first needle down movement in the sewing start phase: the machine needle first passes through the front hole slot (122) downward, then exits the front hole slot (122) upward and is lifted to a suitable position above the needle plate; the thread take-up lever of the sewing machine takes up the thread upward and drives the upper thread on the needle to retreat, and the upper thread is stored in the process of the thread take-up lever taking up the thread upward; the sewing thread on the machine needle remains in the front hole slot (122) of the first movable knife (12); S5, the driving assembly drives the first movable knife (12) to continue to retreat, and the second movable knife to continue to advance; the second movable knife (22) slides on the surface of the first movable knife (12); the front hole groove (122) of the first movable knife (12) approaches the second cutting edge (221) with the sewing thread; the first cutting edge (121) and the second cutting edge (221) approach each other and cut the sewing thread in the front hole groove (122) when they overlap; S6, thread trimming is completed at the seam-starting stage; the driving assembly drives the first movable knife (12) and the second movable knife to reset; S7, continue sewing until the sewing is completed; S8, executing the thread trimming to end the sewing stage, the driving assembly drives the first movable knife (12) to move toward the needle, the front hole slot (122) reaches the first set position (a1), the thread hooking slot (123) is in the second set position (a2), and the opening (1231) of the thread hooking slot faces the sewing thread; the second movable knife (22) remains stationary; S9, the thread hooking groove (123) completes the thread hooking action of the sewing thread; S10, the driving assembly drives the first movable knife (12) to retreat and the second movable knife to advance; the first movable knife and the second movable knife move toward each other and approach each other; the second movable knife (22) slides on the surface of the first movable knife (12); the sewing thread in the thread hooking groove (123) enters the front hole groove (122), and the first cutting edge (121) and the second cutting edge (221) cooperate to cut the sewing thread in the front hole groove (122); S11, the driving assembly drives the first movable knife (12) and the second movable knife to reset, and the thread trimming in the sewing stage is completed.

2. The thread trimming method of a sewing machine with a double movable knife assembly according to claim 1, characterized in that: The step S4 is performed in step S2: when the front hole slot (122) passes the second set position (a2) for the first time, step S4 is performed first, and then the first movable knife (12) is moved; when the front hole slot (122) passes the second set position for the second time, step S5 is directly performed; The sewing machine is equipped with an electronic thread tensioner. When the thread take-up lever takes up the thread in step S4, the electronic thread tensioner locks the upper thread and stops supplying the upper thread to the needle.

3. The thread trimming method of a sewing machine with a double movable knife assembly according to claim 1, characterized in that: The first movable knife assembly (10) includes a first movable knife holder and the first movable knife; 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); The second movable knife assembly comprises a second movable knife holder (21) and the second movable knife; a second ring portion (211) 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 (212) and the second movable knife (22) are provided on the second ring portion.

4. The thread trimming method for a sewing machine with a double-movable knife assembly according to claim 3, wherein: 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.

5. The thread trimming method for a sewing machine with a double-movable knife assembly according to claim 2, wherein: The thread cutting mechanism 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); The driving assembly is used to drive the first transmission assembly (40) and the second transmission assembly (50); The second transmission assembly (50) includes an intermittent motion mechanism (59); during the process of the first movable knife (12) rotating from an initial position to the first set position (a1), the intermittent motion mechanism (59) isolates the power transmission between the drive assembly and the second movable knife assembly (20); during the process of the first movable knife (12) rotating from the first set position (a1) to the initial position, the intermittent motion mechanism (59) transmits the power of the drive assembly to the second movable knife assembly (20).

6. The thread trimming method for a sewing machine with a double-movable knife assembly according to claim 5, 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 driving assembly, 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 driving assembly; 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); during the process of the first movable knife (12) rotating from the initial position to the first set position (a1), the abutting portion moves or deforms and offsets the transmission of the driving cam (51), and during the process of the first movable knife (12) rotating from the first set position (a1) to the initial position, the abutting portion (54) transmits power to the second driving crank (52).

7. The thread trimming method for a sewing machine with a double movable knife assembly according to claim 6, 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) provided 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; when the first movable knife (12) rotates from the initial position to the first set position (a1), the wheel surface of the driving cam (51) passes over the end (544) of the moving rod.

8. The thread trimming method for a sewing machine with a double-movable knife assembly according to claim 5, wherein: 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 of the driving assembly, the swinging 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 swinging of the third crank (61) drives the first transmission shaft (63) to rotate; the other end of the first transmission shaft (63) directly or indirectly drives the first movable knife assembly (10).

9. The thread trimming method for a sewing machine with a double-movable knife assembly according to claim 5, wherein: 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); the second driving 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 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; 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.

10. The thread trimming method of a sewing machine with a double movable knife assembly according to claim 9, characterized in that: The end of the second transmission shaft (73) extends out of the first transmission shaft (63) and is installed with a sixth crank (74), the swing end of the sixth crank (74) is hinged with a fourth connecting rod (75), and the other end of the fourth connecting rod (75) is hinged with the second driving part (212) of the second ring part; A fourth crank (64) is installed at the end of the first transmission shaft (63), and a third connecting rod (65) is hinged to the swing end of the fourth crank (64); the other end of the third connecting rod (65) is hinged to the first driving part (112) of the first ring part (111).

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