A nest line cutting control method

Abstract

The present application provides a kind of little bird nest thread trimming control method, configure little bird nest thread trimming mechanism, little bird nest thread trimming mechanism includes auxiliary knife, movable knife and thread clamping assembly, movable knife is equipped with sewing thread trimming blade edge, sewing thread hooking groove and avoiding needle passing groove;Sewing first needle, needle passes through sewing thread hooking groove, the thread end on the side of needle is brought to the lower of movable knife;Sewing first needle needle moves up, movable knife moves, so that avoiding needle passing groove is located directly below needle, and thread clamping assembly clamps thread end;Sewing machine sewing second needle, third needle,..., until Nth needle, in the process of sewing Nth needle, thread end is cut, when thread lifting lever moves up to target position A, movable knife moves towards auxiliary knife direction, sewing thread trimming blade edge is engaged with auxiliary knife and cuts thread end, and target position A is the non-highest point position of thread lifting lever;Thread lifting lever continues to move up, retracts the thread under sewing material, and tightens bottom thread, reduces bird nest length, and more reliably realizes sewing little bird nest.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and in particular to a method for controlling thread cutting with fewer bird nests. Background Technology

[0002] A flatbed sewing machine is a type of sewing machine that forms lockstitch stitches and is widely used in various sewing processes, capable of sewing various fabrics. However, during the initial lockstitch formation process, the flatbed sewing machine often pulls the bobbin thread under the fabric, where it becomes entangled and intertwined. Because the lengths of the pulled-down threads vary, the area of ​​intertwining and entanglement varies, a feature known in the industry as a "bird's nest." This bird's nest formation at the initial sewing stage is unsightly and unacceptable, especially for garments requiring high sewing quality. Currently, there are two main methods available on the market for addressing this bird's nest formation at the initial sewing stage.

[0003] Method 1: Manual removal. However, this method significantly increases the labor intensity of workers, resulting in high labor costs, substantial investment, significant time wastage, and low efficiency.

[0004] Method 2: Use a bird's nest thread cutter to cut the top thread end when starting to sew. However, existing bird's nest thread cutters are very prone to the top thread detaching after cutting the thread at the start of the sew, which makes it impossible to form a good stitch and reduces the sewing quality.

[0005] Therefore, the current technologies and methods for removing or reducing bird nests on the market cannot adequately meet customers' requirements for sewing quality. Summary of the Invention

[0006] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a method for controlling the cutting of threads with fewer bird nests, which can both reduce the number of bird nests at the start of the seam and reliably prevent the top thread from detaching.

[0007] To achieve the above objectives, the present invention provides a method for controlling nest line trimming, comprising the following steps:

[0008] S1. Configure a low-nest thread cutting mechanism, which includes an auxiliary knife, a movable knife that can move toward or away from the auxiliary knife, and a thread clamping assembly. The movable knife is provided with a starting thread cutting edge, a starting thread hook groove that allows the sewing machine needle to pass through, and a needle avoidance groove.

[0009] S2. Before the sewing machine starts the first stitch, or during the process of the sewing machine needle moving down to start the first stitch, the movable knife moves so that the starting stitch hook groove is located directly below the needle.

[0010] S3. The sewing machine begins the first stitch, and the needle moves down, passing through the starting stitch hook groove. Under the action of the rotary hook in the sewing machine, the thread end on one side of the needle is brought to the bottom of the movable knife.

[0011] S4. The sewing machine starts sewing the first stitch and the needle moves upward. After the needle moves upward from the movable blade, the movable blade moves so that the needle clearance groove is directly below the needle. The movable blade pulls out at least part of the top thread end. At the same time, the thread clamping assembly clamps the top thread end.

[0012] S5. The sewing machine starts sewing the second stitch, the third stitch, ..., up to the Nth stitch. The needle moves up and down in the needle groove and cuts the thread end during the Nth stitch. N≥2.

[0013] When the sewing machine starts sewing the Nth stitch, the needle moves down from the needle clearance groove, the rotary hook hooks the thread to form a thread loop, and the take-up lever in the sewing machine moves up to start taking in the thread;

[0014] When the thread take-up lever moves up to the target position A, the movable blade moves towards the auxiliary blade until the starting seam cutting edge engages with the auxiliary blade to cut the thread end. The target position A is the non-highest point position of the thread take-up lever.

[0015] S6. The thread take-up lever continues to move upward, pulling back the top thread below the seam material and tightening the bottom thread.

[0016] Furthermore, the nest-cutting mechanism also includes a fixed suction pipe with a suction port aligned with the movable blade and / or rotary hook.

[0017] In step S3, the air intake draws in air and picks up the thread end on one side of the needle and the bottom thread end on the rotary hook.

[0018] In step S5, the cut thread ends are collected through the air inlet.

[0019] Furthermore, the movable blade is also provided with a post-sewing thread-cutting edge, and the air intake is arranged along the axis of the rotary hook in the sewing machine, facing the rotary hook, and the air intake is also arranged below the upper end of the rotary hook; the method for controlling thread cutting in bird nests further includes the following steps:

[0020] S7. When sewing is finished and thread cutting is required, the movable blade moves toward the auxiliary blade. The movable blade will bring the bottom thread and top thread together toward the auxiliary blade until the post-sewing thread cutting edge engages with the auxiliary blade and cuts the top thread and bottom thread.

[0021] S8. The air intake draws in air, picks up the bottom thread end on the rotary hook, and makes the bottom thread end angled downwards, located on the path of the top thread loop.

[0022] Furthermore, the initial seam cutting edge and the post-seam cutting edge are the same common cutting edge.

[0023] Furthermore, the air intake is positioned near the detachment side of the thread loop on the rotary shuttle.

[0024] Furthermore, the nest-cutting mechanism also includes a fixedly installed wire pressing plate, the surface of the movable blade is provided with a first wire clamping part, the wire pressing plate is provided with a second wire clamping part, and the first wire clamping part and the second wire clamping part constitute a wire clamping assembly.

[0025] In step S4, a clamping seam is formed between the first clamping part and the second clamping part, and the end of the face thread is clamped in the clamping seam.

[0026] Furthermore, the surface of the movable blade is provided with a first wire clamping portion, and the auxiliary blade is provided with a third wire clamping portion, the first wire clamping portion and the third wire clamping portion constituting a wire clamping assembly;

[0027] In step S4, a clamping seam is formed between the first clamping part and the third clamping part, and the end of the face thread is clamped in the clamping seam.

[0028] Furthermore, the avoidance groove is an empty area formed on the outer periphery of the movable blade.

[0029] Furthermore, the avoidance groove is provided near the starting seam cutting edge, and the outer edge of the movable knife is provided with a transition surface distributed between the avoidance groove and the starting seam cutting edge, the transition surface being a slope or an arc surface.

[0030] Furthermore, the movable blade is rotatably mounted below the sewing machine base plate, and the auxiliary blade is fixedly mounted, movably mounted, or rotatably mounted below the sewing machine base plate.

[0031] As described above, the method for controlling nest trimming in this invention has the following beneficial effects:

[0032] Before cutting the top thread end at the start of the seam, this application first sets the stitch count. During this process, the top thread end is held by the thread clamping component, reliably preventing the top thread from coming loose. In particular, when cutting the top thread end during the Nth stitch of the start-up, this application does so at a position other than the highest point when the take-up lever is rising. Thus, after cutting the top thread end, the take-up lever continues to rise, pulling back the cut top thread below the fabric, while simultaneously tightening the bobbin thread as well. By pulling back the top thread, the length of the bird's nest is further reduced, more reliably achieving fewer bird's nests at the start of the seam. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the bird nest trimming mechanism of this application.

[0034] Figures 2a to 2f This is a schematic diagram of the structure of several embodiments of the movable blade in Embodiment 1 of the Bird's Nest wire-cutting mechanism.

[0035] Figure 3 This is a schematic diagram of the auxiliary blade in Embodiment 1 of the Bird's Nest wire-cutting mechanism.

[0036] Figures 4a to 4d A schematic diagram of the wire-cutting process in Embodiment 1 of the Bird's Nest wire-cutting mechanism.

[0037] Figure 5 This is a schematic diagram showing the connection between the first wire-cutting drive source and the movable blade in Embodiment 1 of the Bird's Nest wire-cutting mechanism.

[0038] Figure 6 This is a schematic diagram of the suction port at the end of the sewing process after the thread is cut, as shown in Embodiment 1 of the Bird's Nest thread-cutting mechanism.

[0039] Figure 7 This is a schematic diagram of the suction port at the start of the thread-cutting mechanism for the Bird's Nest stadium during the thread-cutting process, as shown in Embodiment 1.

[0040] Figure 8 This is a schematic diagram of the structure of Embodiment 2 of the bird nest trimming mechanism of this application, showing only the movable blade and the auxiliary blade.

[0041] Figures 9a to 9d A schematic diagram of the wire-cutting process in Embodiment 2 of the wire-cutting mechanism for reducing bird nests.

[0042] Figure 10 This is a schematic diagram of the structure of Embodiment 3 of the bird nest trimming mechanism of this application.

[0043] Figure 11 This is a schematic diagram of the structure of Embodiment 4 of the bird nest trimming mechanism of this application.

[0044] Figure 12 This is a schematic diagram of the structure of Embodiment 5 of the bird nest trimming mechanism of this application.

[0045] Figure 13 This is a schematic diagram of the first wire-cutting cam in Embodiment 5 of the Bird's Nest wire-cutting mechanism.

[0046] Component designation explanation

[0047] 10 needles

[0048] 20 Rotary Shuttle

[0049] 30 Support Knives

[0050] 31 Third clamping section

[0051] 32 Auxiliary knife thread cutting blade

[0052] 33 Second Raise of the Wings

[0053] 40 movable knives

[0054] 41. Seam opening groove

[0055] 42. Shared wire cutting edge

[0056] 43 cable trays

[0057] 44. Cutting the tip of the thread.

[0058] 45. Avoid passing through the needle groove

[0059] 46. ​​Rippled edge

[0060] 47. Bulging through hole

[0061] 48 Transition Surface

[0062] 49. Post-sewing seam groove

[0063] 410 and above seam groove

[0064] 411 First clamping section

[0065] 412 First Raise of the Blade Wings

[0066] 50 Sewing Machine Base Plate

[0067] 51 Guide groove

[0068] 61 First wire-cutting drive source

[0069] 62 Wire Cutting Drive Shaft

[0070] 63 First Wire Cutting Crank

[0071] 64 First wire-cutting link

[0072] 65 Moving tool holder

[0073] 70 Suction pipe

[0074] 71 Air intake

[0075] 81 Second wire-cutting drive source

[0076] 82 Second Wire Cutting Crank

[0077] 83 Second wire-cutting link

[0078] 84 First return spring

[0079] 91 Wire Cutting Drive Motor

[0080] 92 First wire-cutting cam

[0081] 921 Seam Cutting Drive Section

[0082] 922 Post-sewing thread cutting drive section

[0083] 93 Second wire-cutting cam

[0084] 94 First drive shaft

[0085] 95 First transmission crank

[0086] 96 Second transmission crank

[0087] 97 First Roller

[0088] 98 First transmission link

[0089] 99 First knife holder

[0090] 910 Second drive shaft

[0091] 911 Third Transmission Crank

[0092] 912 Fourth Transmission Crank

[0093] 913 Second Roller

[0094] 914 Second transmission link

[0095] 915 Second Tool Holder

[0096] 916 Second return spring

[0097] 917 Third Return Spring

[0098] 110 Bottom line end Detailed Implementation

[0099] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0100] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0101] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0102] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0103] This application relates to the field of sewing machine technology, and in particular to a method for controlling thread trimming with fewer bird nests. Typically, such as... Figure 1 As shown, the sewing machine is equipped with a needle 10 that can move up and down reciprocally, and a rotary hook 20 that can rotate. In the following embodiments, the axial direction of the rotary hook 20 is defined as the left-right direction, the extension direction of the needle 10 is defined as the up-down direction, and the direction orthogonal to both the left-right and up-down directions is defined as the front-back direction, with the front direction being the direction in which the fabric moves when the sewing machine is sewing forward.

[0104] The method for controlling nest line cutting involved in this application includes the following steps in sequence.

[0105] Step S1: Configure a nest-cutting mechanism; such as Figure 1 As shown, the bird's nest trimming mechanism includes an auxiliary blade 30, a movable blade 40 capable of moving towards or away from the auxiliary blade 30, and a wire clamping assembly. Figure 2a As shown, the movable blade 40 is equipped with a thread-cutting edge for starting the sewing, a thread-cutting groove 41 that allows the sewing machine needle 10 to pass through, and a needle-avoiding groove 45. Figure 3 As shown, the lower surface of the auxiliary knife 30 is provided with an auxiliary knife thread cutting edge 32. By moving the movable knife 40, the starting stitch hook groove 41 can be moved to directly below the needle 10 in the sewing machine, or the bypass groove 45 can be moved to directly below the needle 10 in the sewing machine, or the starting stitch cutting edge can be engaged with the auxiliary knife thread cutting edge 32 of the auxiliary knife 30.

[0106] Step S2: Before the sewing machine starts the first stitch, or during the process of the sewing machine needle 10 moving down to start the first stitch, the movable blade 40 moves so that the starting stitch hook groove 41 is located directly below the needle 10.

[0107] Step S3: The sewing machine moves the needle 10 down to begin the first stitch, passing through the starting stitch hook groove 41, as shown. Figure 4a As shown, under the hooking action of the rotary hook 20 in the sewing machine, the thread end on one side of the needle 10 is brought to the lower part of the movable blade 40, that is, to the vicinity of the rotary hook 20.

[0108] Step S4: The sewing machine begins the first stitch, with the needle 10 moving upwards. After the needle 10 moves upwards from the movable blade 40, the movable blade 40 moves so that the clearance groove 45 is directly below the needle 10. Figure 4c As shown, the movable blade 40 pulls out at least a portion of the thread end, while the thread clamping assembly holds the thread end in place.

[0109] Step S5: The sewing machine begins sewing the second, third, ..., up to the Nth stitch. The needle 10 moves up and down within the needle clearance groove 45, and cuts the thread end during the start of the Nth stitch, N≥2. When the sewing machine begins sewing the Nth stitch, the needle 10 moves down from within the needle clearance groove 45, piercing through the groove without interfering with the movable blade 40. Then, the rotary hook 20 hooks the thread to form a thread loop. When the thread loop expands to its maximum size, it passes through the bottom of the shuttle case of the rotary hook 20. Then, the take-up lever in the sewing machine moves up to begin taking in the thread, and the thread loop at the bottom gradually contracts, gradually pulling the thread out of the rotary hook 20 track. When the take-up lever moves up to the target position A (the position A is not the highest point of the take-up lever), the movable blade 40 moves towards the auxiliary blade 30. Figure 4d As shown, the thread cutting edge engages with the auxiliary knife 30 until the thread end is cut off, thus preventing the thread end from tangling and forming a bird's nest.

[0110] Step S6: Since target position A is not the highest point of the thread take-up lever, after the top thread is cut off, the thread take-up lever continues to move upward, pulling back the top thread that was cut below the sewing material, and at the same time tightening the bottom thread as well, further reducing the length of the bird's nest by pulling back the top thread.

[0111] Therefore, this application first sets the stitch count before cutting the top thread end at the start of the seam. During this process, the top thread end is held by the thread clamping component, reliably preventing the top thread from coming loose. In particular, this application cuts the top thread end during the Nth stitch of the start-up process at a position other than the highest point when the take-up lever is rising. Thus, after cutting the top thread end, the take-up lever continues to rise, pulling back the cut top thread below the fabric, while simultaneously tightening the bobbin thread as well. By pulling back the top thread, the length of the nest is further reduced, more reliably achieving fewer nests at the start of the seam.

[0112] Several embodiments of a bird nest trimming mechanism are provided below.

[0113] Example 1 of a bird nest wire-cutting mechanism

[0114] like Figure 1 As shown, in Embodiment 1 of the nest-cutting mechanism, the movable blade 40 and the auxiliary blade 30 are distributed radially along the rotary hook 20, with the movable blade 40 positioned below the auxiliary blade 30. Figure 2a As shown, the movable blade 40 is also equipped with a post-seam thread-cutting edge. The starting thread-cutting edge and the post-seam thread-cutting edge are the same common thread-cutting edge 42. The starting thread hook groove 41 is distributed on the side of the common thread-cutting edge 42 facing the auxiliary blade 30. When the sewing machine starts sewing, the common thread-cutting edge 42 engages with the auxiliary blade 30 to cut the top thread end; when the sewing machine finishes sewing, the common thread-cutting edge 42 engages with the auxiliary blade 30 to cut the top thread and bottom thread, thereby reliably achieving minimal thread nesting at the start of the sewing and automatic thread cutting at the end of sewing. In addition, this application sets the starting thread-cutting edge and the post-seam thread-cutting edge to the same common thread-cutting edge 42, which is simple in structure, easy to implement, and does not require additional processing of the thread-cutting edge on the existing movable blade. This reduces the need for modification to the movable blade in the existing sewing machine, lowers the modification cost, and has strong versatility.

[0115] Furthermore, in Embodiment 1 of the nest-cutting mechanism, a single-moving-blade and single-fixed-blade structure is adopted. Specifically, the movable blade 40 is rotatably mounted below the sewing machine base plate 50, and the rear end of the auxiliary blade 30 is fixed to the bottom of the sewing machine base plate 50 by screws. The movable blade 40 moves closer to or further away from the auxiliary blade 30 by rotating back and forth. Initially, the movable blade 40 and the auxiliary blade 30 are distributed on both sides of the needle 10, with the movable blade 40 positioned in front of the needle 10 and the auxiliary blade 30 positioned behind it.

[0116] Furthermore, such as Figure 5 As shown, the first embodiment of the bird's nest thread cutting mechanism also includes a first thread cutting drive source 61, a thread cutting drive shaft 62 rotatably supported in the sewing machine base plate 50, a first thread cutting crank 63 fixed on the thread cutting drive shaft 62, a first thread cutting connecting rod 64, and a movable blade holder 65 rotatably supported in the sewing machine base plate 50. The first thread cutting drive source 61 is a motor, preferably a stepper motor. The first thread cutting drive source 61 is connected to the thread cutting drive shaft 62 and drives the thread cutting drive shaft 62 to rotate. The two ends of the first thread cutting connecting rod 64 are respectively hinged to the first thread cutting crank 63 and the movable blade holder 65. The right end of the movable blade 40 is fixed to the movable blade holder 65 by screws, and two fixing holes are opened in the right end of the movable blade 40. When the first wire cutting drive source 61 drives the wire cutting drive shaft 62 to rotate, the first wire cutting crank 63 rotates together with the wire cutting drive shaft 62, and drives the moving blade holder 65 to rotate back and forth through the first wire cutting connecting rod 64. The movable blade 40 rotates back and forth together with the moving blade holder 65, which drives the movable blade 40 to rotate backward toward the auxiliary blade 30 or forward away from the auxiliary blade 30.

[0117] Furthermore, since the auxiliary blade 30 is distributed on the rear side of the movable blade 40, the seam-starting groove 41 is distributed on the rear side of the common thread-cutting edge 42. Preferably, the movable blade 40 has an arc-shaped blade body, and the extension trajectory of the arc-shaped blade body is basically consistent with the rotation trajectory of the movable blade 40. For example... Figure 2a or Figure 2b As shown, the movable blade 40 is provided with a thread-separating groove 43 and a thread-cutting and separating tip 44. The common thread-cutting blade 42 and the thread-cutting and separating tip 44 are respectively located on the front and rear sides of the movable blade 40, and the thread-separating groove 43 is distributed between the common thread-cutting blade 42 and the thread-cutting and separating tip 44. When cutting the thread at the end of sewing, the thread-cutting and separating tip 44 and the thread-separating groove 43 work together to separate the bottom thread and the top thread.

[0118] Furthermore, there are various ways to set the starting stitch hook groove 41 and the needle avoidance groove 45 on the movable knife 40, so that the movable knife 40 has multiple embodiments.

[0119] Example 1 of the movable knife 40 Figure 2a As shown, the movable blade 40 has a protruding blade bulge 46 at the common thread-cutting edge 42. A through-hole 47, which runs vertically through the bulge 46, is formed within the bulge 46. The through-hole 47 is a circular hole, and its front edge forms the common thread-cutting edge 42. The through-hole 47 also forms the starting stitch hook groove 41. The avoidance needle groove 45 is an empty area formed on the front edge side of the movable blade 40, and is located adjacent to the starting stitch hook groove 41. Preferably, the outer edge of the movable blade 40 has a transition surface 48 distributed between the avoidance needle groove 45 and the common thread-cutting edge 42. The transition surface 48 is a sloped or arc-shaped surface, and it smoothly transitions to the outer edge of the surrounding movable blade 40. After the thread is cut at the end of sewing, the movable blade 40 rotates forward to reset. During this process, the transition surface 48 gently pushes aside the bottom thread to prevent pulling. Along the circumference of the movable blade 40, the needle groove 45, the common thread cutting edge 42, the starting thread hook groove 41, and the thread separating groove 43 are distributed on the same circumference of the movable blade 40, and are distributed sequentially from front to back. In addition, a sewing thread receiving groove 49 is provided on the upper surface of the movable blade 40. The front and rear ends of the sewing thread receiving groove 49 are respectively connected between the common thread cutting edge 42 and the thread separating groove 43. The sewing thread receiving groove 49 is used to receive the top thread and the bottom thread when the thread is cut at the end of sewing.

[0120] Example 2 of the movable knife 40 Figure 2bAs shown, the starting stitch hook groove 41 is positioned away from the common thread cutting edge 42, which is near the front side of the movable blade 40. The starting stitch hook groove 41 is near the rear side of the movable blade 40. The thread dividing groove 43 is distributed between the common thread cutting edge 42 and the starting stitch hook groove 41. The movable blade 40 has a protruding blade edge bulge 46 at the common thread cutting edge 42, and a through-hole 47 is formed in the bulge 46. The front edge of the through-hole 47 constitutes the common thread cutting edge 42. The needle clearance groove 45 is an empty area formed on the front edge side of the movable blade 40. Preferably, the upper surface of the movable blade 40 is provided with a sewing start groove 410 and a sewing finish groove 49. The front and rear ends of the sewing start groove 410 are connected between the common thread cutting edge 42 and the sewing start hook groove 41, and the front and rear ends of the sewing finish groove 49 are respectively connected between the common thread cutting edge 42 and the thread separating groove 43. Since the common thread cutting edge 42, the thread separating groove 43, and the sewing start hook groove 41 are arranged sequentially from front to back, the sewing finish groove 49 is a part of the sewing start groove 410. In the second embodiment of the movable blade 40, since the sewing start hook groove 41 is located away from the common thread cutting edge 42, during the process of cutting the thread end of the face thread, a larger amount of face thread end can be pulled out to the upper surface of the movable blade 40, and this part of the face thread end is accommodated in the sewing start groove 410.

[0121] Embodiment 3 of the movable knife 40 differs from Embodiment 1 of the movable knife 40 only in that: Figure 2c As shown, the seam inlet groove 41 is distributed between the bulge through hole 47 and the dividing groove 43. The seam inlet groove 41 is located adjacent to the bulge through hole 47. The seam inlet groove 41 is a through groove that runs vertically and is a closed groove structure. The seam inlet groove 41 is not connected to the bulge through hole 47. The seam inlet groove 41 is an oblong hole that extends front to back.

[0122] Embodiment 4 of the movable knife 40 differs from Embodiment 3 of the movable knife 40 only in that: Figure 2d As shown, the front end of the seam inlet groove 41 extends forward to the rear end of the bulge through hole 47, that is, the seam inlet groove 41 and the bulge through hole 47 are connected and merged into a single structure.

[0123] Embodiment 5 of the movable knife 40 differs from Embodiment 3 of the movable knife 40 only in that: Figure 2e As shown, the seam initiation groove 41 is an open groove structure with an opening on the left side, and the left end of the seam initiation groove 41 extends to the left edge of the movable blade 40.

[0124] Embodiment 6 of the movable knife 40 differs from Embodiment 3 of the movable knife 40 only in that: Figure 2f As shown, the seam opening groove 41 is a round hole.

[0125] Furthermore, in the six embodiments of the movable blade 40 described above, a first lifting wing 412 extending rearward is integrally provided on the right end of the rear edge of the movable blade 40 for lifting the auxiliary blade 30, so that the movable blade 40 and the auxiliary blade 30 can better engage. Of course, provided that the movable blade 40 and the auxiliary blade 30 can engage well, the first lifting wing 412 may not be provided on the movable blade 40. Preferably, a second lifting wing 33 is integrally provided on the side of the auxiliary blade 30 for abutting against the movable blade 40, so that the movable blade 40 and the auxiliary blade 30 can better engage. Of course, provided that the movable blade 40 and the auxiliary blade 30 can engage well, the second lifting wing 33 may not be provided on the auxiliary blade 30.

[0126] Furthermore, the wire clamping assembly preferably has the following two configurations.

[0127] Method 1: The thread end is clamped by the movable blade 40 and an additionally provided pressure plate. Based on this, the first embodiment of the nest-cutting mechanism also includes a fixed pressure plate; along the radial direction of the rotary hook 20, the pressure plate, auxiliary blade 30, and movable blade 40 are distributed from the outside to the inside; the upper surface of the movable blade 40 is provided with a first thread clamping part 411, and the pressure plate is provided with a second thread clamping part, the first thread clamping part 411 and the second thread clamping part constitute a thread clamping assembly. In the above step S4, when the movable blade 40 moves to avoid the needle groove 45 and is located directly below the needle 10, a thread clamping seam for clamping the thread end is formed between the first thread clamping part 411 and the second thread clamping part. Preferably, the pressure plate can be fixed on the auxiliary blade 30, or it can be directly fixed to the bottom of the sewing machine base plate 50.

[0128] Method 2: The thread end is held by the movable blade 40 and the auxiliary blade 30. Based on this, such as... Figure 3 and Figure 4c As shown, the upper surface of the movable blade 40 is provided with a first thread clamping portion 411, and the lower surface of the auxiliary blade 30 is provided with a third thread clamping portion 31. The auxiliary blade cutting edge 32 of the auxiliary blade 30 is distributed on the rear side of the third thread clamping portion 31. The first thread clamping portion 411 and the third thread clamping portion 31 constitute a thread clamping assembly. In step S4 above, when the movable blade 40 moves to avoid the needle groove 45 and is located directly below the needle 10, a thread clamping seam for clamping the thread end is formed between the first thread clamping portion 411 and the third thread clamping portion 31.

[0129] Furthermore, such as Figure 1As shown, the first embodiment of the nest-cutting mechanism includes an air suction device, which includes an air source and an air suction pipe 70. The air source is installed on a fixed frame, or on the base plate of the sewing machine, or placed directly on the ground. One end of the air suction pipe 70 is connected to the air source, and the other end of the air suction pipe 70 is an air suction port 71, which is aligned with the movable blade 40 and / or the rotary hook 20. In step S3 above, the air suction port 71 draws in air, picking up the top thread end on one side of the needle 10 and the bottom thread end 110 on the rotary hook 20, thus pre-capturing the top thread end and the bottom thread end 110 when cutting the top thread end at the start of sewing. In step S5 above, the cut top thread end is collected through the air suction port 71, realizing the automatic collection of the cut top thread end.

[0130] Furthermore, in this embodiment, as Figure 1 As shown, the air intake 71 is positioned along the axial direction of the rotary hook 20 in the sewing machine, that is, the air intake 71 is located on the left side of the rotary hook 20, and the air intake 71 is also positioned lower than the upper end of the rotary hook 20. Based on this, the method for controlling thread cutting in bird nests also includes the following steps:

[0131] Step S7: When sewing is finished and the thread needs to be cut, the movable blade 40 moves towards the auxiliary blade 30. The movable blade 40 will bring the bottom thread and the top thread together to the auxiliary blade 30 until the thread cutting edge of the post-sewing tool engages with the auxiliary blade 30 and cuts the top thread and bottom thread.

[0132] Step S8: Inhale through the air inlet 71, pick up the bottom thread end 110 on the rotary hook 20, and make the bottom thread end 110 angled downwards, located on the path of the top thread loop.

[0133] Preferably, the air inlet 71 is located near the detachment side of the thread loop on the rotary hook 20, that is, in the front-back direction, the air inlet 71 is close to the front side of the rotary hook 20, which is more conducive to the thread loop wrapping the bottom thread.

[0134] The working principle of the first embodiment of the bird nest trimming mechanism is described below, taking the configuration of the movable blade 40 in the first embodiment of the bird nest trimming mechanism, the movable blade 40 and the auxiliary blade 30 working together to clamp the thread end, and the air intake 71 located on the left side of the rotary shuttle 20 as an example.

[0135] 1.1 Before or simultaneously with the first stitch, the movable cutter 40 rotates backward so that the starting thread groove 41 is directly below the needle 10; then, as the needle 10 moves down for the first stitch, the needle 10, carrying the top thread, passes downward through the starting thread groove 41, as... Figure 4aAs shown, under the hooking action of the rotary hook 20, the top thread end on one side of the needle 10 is brought to below the movable blade 40, that is, to the vicinity of the rotary hook 20. During this process, the electronic thread clamp on the sewing machine can be activated to more reliably bring the top thread end on the needle 10 side to below the movable blade 40. At the same time, the air source is turned on, and the suction port 71 of the suction device sucks up the top thread end and the bottom thread end 110, as... Figure 4b As shown; in particular, the suction device shall provide suction power no later than after the shuttle hook 20 hooks the thread and brings the head of the top thread to the shuttle case.

[0136] 1.2. The first stitch is started with needle 10. Needle 10 moves upwards, and after it moves out of the starting stitch groove 41, the movable blade 40 rotates backwards towards the auxiliary blade 30. Figure 4c As shown, the first thread clamping part 411 of the movable blade 40 just comes into contact with the third thread clamping part 31 of the auxiliary blade 30, and the two press and clamp the thread end. At the same time, the clearance groove 45 of the movable blade 40 is located directly below the needle 10.

[0137] 1.3 The sewing machine continues to sew the second and third stitches, and cuts the thread end during the process of forming a loop at the set starting point N stitches, where N≥2. For example: during the process of forming a loop at the starting point of the second stitch, the thread end is cut, the needle 10 moves down, and the needle 10 passes through the avoidance needle groove 45 without interfering with the movable knife 40; then the rotary hook 20 hooks the thread to form a loop, and when the loop expands to its maximum size, it will pass the bottom of the shuttle case of the rotary hook 20. At this time, the loop will contact the thread end sucked by the suction port 71; then the take-up lever begins to take in the thread, and the bottom loop gradually contracts, gradually lifting the thread out of the rotary hook 20 track. When the take-up lever rises back to its target position A (not its highest point), the movable knife 40 continues to rotate backward toward the auxiliary knife 30, as... Figure 4d As shown, the thread-cutting blade 42 engages with the auxiliary blade 30 to cut the top thread end, thus preventing the top thread end from tangling and forming a bird's nest. The cut top thread end is then sucked away by the suction port 71. Afterward, the thread take-up lever continues to rise, pulling back the cut top thread below the fabric, while simultaneously tightening the bottom thread as well. This pullback further reduces the length of the bird's nest. The specific point in the stitching process where the top thread end is cut during the loop formation is adjusted based on the desired effect.

[0138] 1.4 After the seam is cut, the movable blade 40 rotates forward away from the auxiliary blade 30 until it returns to its original position. During this process, the bottom thread passes through the transition surface 48 of the movable blade 40 without affecting the position of the bottom thread or the tension of the thread. The air source is turned off and the air intake 71 stops sucking air.

[0139] 1.5. The sewing machine performs normal sewing.

[0140] 1.6 When sewing is finished and thread cutting is required, the movable blade 40 rotates backward, first passing the thread-sewing tip 44 through the top thread loop; as the movable blade 40 continues to rotate backward, the bottom thread and top thread on the side to be cut slide into the thread-sewing groove 43, and then the bottom thread and top thread are accommodated in the sewing post-sewing groove 49; when the common thread-sewing blade 42 engages with the auxiliary blade 30, the top thread and bottom thread are cut. Afterward, the movable blade 40 rotates forward until it returns to its original position.

[0141] 1.7 With the air source turned on, the air intake 71 of the suction device sucks up the bottom thread end 110, causing the bottom thread end 110 to tilt downwards and to the left. Figure 6 As shown. Thus, when starting the next stitch, the bottom thread end 110, tilted downwards and to the left, is positioned on the path of the top thread loop. This helps to lift the bottom thread at the beginning of sewing, reducing the probability of the bottom thread not being lifted during the start-up. Furthermore, the air source is also on during the start-up, making it easier to hold the bottom thread end 110. The direction in which the bottom thread end 110 is held during the start-up is the same as the direction it is held after the thread is cut at the end of sewing. When the top thread loop passes through this point, it will be easier to wrap the bottom thread around. Figure 7 As shown, this helps to create a seam allowance.

[0142] In summary, the first embodiment of the reduced-nest thread trimming mechanism has a simple structure, which can reduce the length of the nest and improve sewing quality; it has a simple structure, low cost, strong durability, and does not take up sewing space; it is highly versatile and can be well applied to existing thread trimming structures on the market, so that they can all achieve the reduced-nest effect after modification; at the same time, it can also greatly reduce the probability of the bottom thread not being pulled up when starting the seam.

[0143] Example 2 of the bird nest wire cutting mechanism

[0144] The difference between Embodiment 2 of the bird nest wire-cutting mechanism and Embodiment 1 of the bird nest wire-cutting mechanism lies only in: Figure 8 As shown, in the initial state, the movable blade 40 and the auxiliary blade 30 are distributed on the same side of the needle 10, which is the rear side in this embodiment, and the movable blade 40 and the auxiliary blade 30 are in an engaged state. Therefore, the working principle of the nest-cutting mechanism embodiment two is described below.

[0145] 2.1 Before or at the same time as starting the first stitch, rotate the movable blade forward by 40 degrees, as follows: Figure 9a As shown, the starting stitch hook groove 41 is positioned directly below the needle 10. Then, when the needle 10 moves down to begin the first stitch, it carries the top thread downwards through the starting stitch hook groove 41. Under the hooking action of the rotary hook 20, the top thread end on one side of the needle 10 is brought to the vicinity of the rotary hook 20. Simultaneously, the air source is turned on, and the suction port 71 of the suction device sucks up the top thread end and the bottom thread end 110.

[0146] 2.2. The first stitch is started with needle 10. Needle 10 moves upwards, and after it moves out of the starting stitch groove 41, the movable blade 40 rotates backwards towards the auxiliary blade 30. Figure 9b As shown, the thread clamping portion 411 of the movable blade 40 comes into contact with the third thread clamping portion 31 of the auxiliary blade 30, and the two clamp the thread end. At the same time, the needle clearance groove 45 of the movable blade 40 is located directly below the needle 10. In addition, the time when the movable blade 40 rotates backward toward the auxiliary blade 30 must not be later than the time when the needle 10 moves down to this position when starting the second stitch, so as to ensure that the needle 10 can pierce within the needle clearance groove 45 when starting the second stitch.

[0147] 2.3 The sewing machine continues to sew the second and third stitches, and cuts the thread end of the surface thread during the process of forming the thread loop at the set starting point of the Nth stitch, where N≥2; the specific process is the same as step 1.3 in the above-mentioned example of the bird nest thread cutting mechanism.

[0148] 2.4 After the seam cutting is completed, the movable blade 40 is in its initial position; at the same time, the air source is turned off and the air intake 71 stops sucking air.

[0149] 2.5 The sewing machine performs normal sewing.

[0150] 2.6 Before the thread needs to be cut at the end of sewing, and when the needle 10 is above the sewing machine needle plate, the movable blade 40 rotates forward away from the auxiliary blade 30, as follows: Figure 9c As shown, the movable blade 40 is rotated to the front of the needle 10, awaiting the post-sewing thread cutting action. Afterwards, when thread cutting is required at the end of sewing, the movable blade 40 rotates backward towards the auxiliary blade 30. First, the thread-sewing tip 44 passes through the top thread loop, then the bottom thread and top thread on the side being cut slide into the thread-sewing groove 43 and are accommodated in the post-sewing thread-receiving groove 49. When the shared thread-sewing blade 42 engages with the auxiliary blade 30, as... Figure 9d As shown, cut the top and bottom threads. After sewing and cutting the threads, the movable blade 40 is in its initial position, and therefore does not need to be reset; it remains in that position.

[0151] Example 3 of the bird nest wire cutting mechanism

[0152] The difference between Embodiment 3 and Embodiment 1 of the bird's nest thread-cutting mechanism lies only in that the auxiliary blade 30 is movably mounted below the sewing machine base plate 50. Based on this, as... Figure 10 As shown, the wire-cutting mechanism for the bird's nest also includes a second wire-cutting drive source 81, which is connected to the auxiliary blade 30 for transmission and drives the auxiliary blade 30 to move back and forth.

[0153] Furthermore, the second thread-cutting drive source 81 is a motor, preferably a stepper motor. The second thread-cutting drive source 81 is fixed to the bottom surface of the sewing machine base plate 50, and is connected to the rear end of the auxiliary blade 30 via a drive transmission mechanism. In this embodiment, the drive transmission mechanism adopts a crank-connecting rod mechanism; based on this, as... Figure 10 As shown, Embodiment 3 of the thread-cutting mechanism for the bird's nest further includes a second thread-cutting crank 82 and a second thread-cutting connecting rod 83 fixed on the motor shaft of the second thread-cutting drive source 81. The two ends of the second thread-cutting connecting rod 83 are hinged to the second thread-cutting crank 82 and the auxiliary blade 30, respectively. The second thread-cutting drive source 81 drives the auxiliary blade 30 to move forward or backward via the second thread-cutting crank 82 and the second thread-cutting connecting rod 83. In other embodiments, the second thread-cutting drive source 81 and the auxiliary blade 30 can also be connected via a gear mechanism or a synchronous belt pulley mechanism. The second thread-cutting drive source 81 can also be fixed to the sewing machine housing, table, or oil pan.

[0154] Preferably, such as Figure 10 As shown, the bottom of the sewing machine base plate 50 is provided with a guide groove 51 that extends straight back and forth. The auxiliary knife 30 is movably mounted in the guide groove 51. Through the sliding guide cooperation between the two, the stability of the auxiliary knife 30 moving back and forth is improved.

[0155] The working principle of the bird nest trimming mechanism in Embodiment 3 is described below.

[0156] 3.1 Before or simultaneously with the first stitch, the movable cutter 40 rotates backward so that the starting stitch hook groove 41 is directly below the needle 10. Then, as the needle 10 moves downward for the first stitch, it carries the top thread through the starting stitch hook groove 41. Under the hooking action of the rotary hook 20, the top thread end on one side of the needle 10 is brought to the vicinity of the rotary hook 20. Simultaneously, the air source is activated, and the suction port 71 of the air suction device sucks up the top thread end and the bottom thread end 110.

[0157] 3.2. The needle 10 starts sewing the first stitch. The needle 10 moves upward. After the needle 10 moves upward from the starting stitch hook groove 41, the movable knife 40 rotates backward toward the auxiliary knife 30. The auxiliary knife 30 can remain stationary or move forward until the first thread clamping part 411 of the movable knife 40 just contacts the third thread clamping part 31 of the auxiliary knife 30, so as to achieve the effect of clamping the thread end. At the same time, the clearance groove 45 of the movable knife 40 is located directly below the needle 10.

[0158] 3.3 The sewing machine continues to sew the second and third stitches, and cuts the thread end of the surface thread during the process of forming a loop at the set starting point of the Nth stitch, where N≥2; the specific process is the same as step 1.3 in the above-mentioned embodiment of the bird's nest thread cutting mechanism. However, in this embodiment, when cutting the thread end of the surface thread, the movable blade 40 remains stationary while the auxiliary blade 30 moves forward; or, the movable blade 40 rotates backward while the auxiliary blade 30 remains stationary; or, the movable blade 40 rotates backward while the auxiliary blade 30 moves forward, so as to achieve the effect of the shared thread cutting edge 42 and the auxiliary blade 30 engaging to cut the thread end of the surface thread.

[0159] 3.4 After the seam cutting is completed, the movable knife 40 and the auxiliary knife 30 are reset; the air source is turned off and the air intake 71 stops sucking air.

[0160] 3.5 The sewing machine performs normal sewing.

[0161] 3.6 When sewing is finished and thread cutting is required, the movable blade 40 rotates backward, first passing through the top thread loop at the thread-sewing tip 44. As the movable blade 40 continues to rotate backward, the bottom and top threads on the side to be cut slide into the thread-sewing groove 43. Then, the bottom and top threads are accommodated in the post-sewing thread-receiving groove 49. The auxiliary blade 30 can remain stationary or move forward until the shared thread-sewing blade 42 engages with the auxiliary blade 30, ultimately cutting the top and bottom threads. Afterward, the movable blade 40 and the auxiliary blade 30 return to their original positions.

[0162] 3.7 When the air source is turned on, the air intake 71 of the air suction device sucks up the bottom thread end 110, causing the bottom thread end 110 to tilt to the lower left.

[0163] Example 4 of the bird nest wire cutting mechanism

[0164] The difference between Embodiment 4 and Embodiment 3 of the wire-cutting mechanism with fewer bird nests lies only in the type of the second wire-cutting drive source 81 and the connection structure between the second wire-cutting drive source 81 and the auxiliary blade 30. Specifically, in Embodiment 4 of the wire-cutting mechanism with fewer bird nests, as... Figure 11 As shown, the second thread-cutting drive source 81 is a cylinder or an electromagnet, which is fixed on the bottom surface of the sewing machine base plate 50; the rear end of the auxiliary knife 30 is directly installed at the end of the piston rod of the cylinder or the end of the iron core of the electromagnet, and the auxiliary knife 30 is directly driven to move forward or backward by the cylinder or the electromagnet, eliminating the need to directly set a drive transmission mechanism between the second thread-cutting drive source 81 and the auxiliary knife 30.

[0165] Additionally, when the second wire-cutting drive source 81 is an electromagnet, such as Figure 11 As shown, a first return spring 84 is sleeved on the iron core of the electromagnet. The two ends of the return spring abut against the housing and the iron core of the electromagnet, respectively, for resetting the iron core.

[0166] The working principle of the wire-cutting mechanism in Example 4 is the same as that in Example 3, and will not be repeated here.

[0167] Example 5 of a bird nest wire-cutting mechanism

[0168] The difference between Embodiment 5 of the bird's nest thread-cutting mechanism and Embodiment 1 is only that: both the movable blade 40 and the auxiliary blade 30 are rotatably mounted below the sewing machine base plate 50. Based on this, as... Figure 12 As shown, Embodiment 5 of the bird nest thread cutting mechanism also includes a thread cutting drive motor 91, a first thread cutting cam 92, a second thread cutting cam 93, a first transmission mechanism, and a second transmission mechanism; the thread cutting drive motor 91 is fixed on the base plate, the machine housing, or the oil pan of the sewing machine; the first thread cutting cam 92 and the second thread cutting cam 93 are both fixed on the motor shaft of the thread cutting drive motor 91. The first thread cutting cam 92 and the second thread cutting cam 93 can be two separate cam components or they can be combined into one cam component; the first thread cutting cam 92 is connected to the movable blade 40 through the first transmission mechanism, and the second thread cutting cam 93 is connected to the auxiliary blade 30 through the second transmission mechanism.

[0169] like Figure 13 As shown, the outer circumferential surface of the first thread-cutting cam 92 is provided with a starting thread-cutting drive section 921 and a post-seam thread-cutting drive section 922. When the sewing machine starts sewing, the starting thread-cutting drive section 921 acts on the first transmission mechanism for thread-cutting control during the starting sewing process. When the sewing machine finishes sewing, the post-seam thread-cutting drive section 922 acts on the first transmission mechanism for normal thread-cutting control at the end of sewing. Furthermore, when the starting thread-cutting drive section 921 of the first thread-cutting cam 92 acts on the first transmission mechanism, there is no power transmission between the second thread-cutting cam 93 and the second transmission mechanism; when the post-seam thread-cutting drive section 922 of the first thread-cutting cam 92 acts on the first transmission mechanism, there is power transmission between the second thread-cutting cam 93 and the second transmission mechanism.

[0170] Furthermore, such as Figure 12 As shown, the first transmission mechanism includes a first transmission shaft 94 rotatably supported in the sewing machine base plate 50, a first transmission crank 95 and a second transmission crank 96 respectively fixed at both ends of the first transmission shaft 94, a first roller 97 rotatably mounted on the outer end of the first transmission crank 95, a first transmission connecting rod 98, and a first blade holder 99. The first roller 97 abuts against the outer peripheral surface of the first thread cutting cam 92. The two ends of the first transmission connecting rod 98 are respectively hinged to the second transmission crank 96 and the first blade holder 99. The movable blade 40 is fixed on the first blade holder 99.

[0171] Furthermore, such as Figure 12As shown, the second transmission mechanism includes a second transmission shaft 910 rotatably supported in the sewing machine base plate 50, a third transmission crank 911 and a fourth transmission crank 912 respectively fixed at both ends of the second transmission shaft 910, a second roller 913 rotatably mounted on the outer end of the second transmission crank 916, a second transmission connecting rod 914, and a second blade holder 915. The second roller 913 abuts against the outer peripheral surface of the second thread cutting cam 93. The two ends of the second transmission connecting rod 914 are respectively hinged to the fourth transmission crank 912 and the second blade holder 915. The auxiliary blade 30 is fixed on the second blade holder 915.

[0172] Preferably, the first transmission mechanism further includes a second return spring 916, which is sleeved on the first transmission shaft 94. One end of the second return spring 916 is fixed, and the other end acts on the second transmission crank 96 for resetting the movable blade 40. The second transmission mechanism also includes a third return spring 917, which is sleeved on the second transmission shaft 910. One end of the third return spring 917 is fixed, and the other end acts on the fourth transmission crank 912 for resetting the auxiliary blade 30.

[0173] The working principle of the bird nest trimming mechanism in embodiment five is described below.

[0174] 4.1 Before or simultaneously with the first stitch, the thread-cutting drive motor 91 drives the first thread-cutting cam 92 and the second thread-cutting cam 93 to rotate. The thread-cutting drive section 921 of the first thread-cutting cam 92 engages with the first roller 97, driving the movable blade 40 to rotate backward via the first transmission mechanism, so that the thread-cutting groove 41 is directly below the needle 10. Meanwhile, the second thread-cutting cam 93 separates from the second roller 913, or the equal-diameter surface on the outer periphery of the second thread-cutting cam 93 engages with the second roller 913, in which case the second transmission mechanism does not operate, and the auxiliary blade 30 remains stationary. Afterward, when the needle 10 moves down during the first stitch, the needle 10, carrying the top thread, passes downward through the thread-cutting groove 41. Under the hooking action of the rotary hook 20, the top thread end on one side of the needle 10 is brought to the vicinity of the rotary hook 20. Simultaneously, the air source is turned on, and the suction port 71 of the suction device sucks up the top thread end and the bottom thread end 110.

[0175] 4.2. The needle 10 starts sewing the first stitch. The needle 10 moves upward. After the needle 10 moves upward from the starting stitch hook groove 41, the thread cutting drive motor 91 continues to drive the first thread cutting cam 92 and the second thread cutting cam 93 to rotate. The starting stitch thread cutting drive section 921 of the first thread cutting cam 92 continues to push the first roller 97, driving the movable knife 40 to continue to rotate backward, while the auxiliary knife 30 remains stationary until the first thread clamping part 411 of the movable knife 40 just contacts the third thread clamping part 31 of the auxiliary knife 30, achieving the effect of clamping the thread end; at the same time, the clearance groove 45 of the movable knife 40 is located directly below the needle 10.

[0176] 4.3 The sewing machine continues to sew the second and third stitches, and cuts the thread end of the surface thread during the process of forming a loop at the set starting point of the Nth stitch, where N≥2; the specific process is the same as step 1.3 in the above-mentioned embodiment of the bird's nest thread cutting mechanism. However, when cutting the thread end of the surface thread, the movable blade 40 continues to rotate backward, while the auxiliary blade 30 remains stationary.

[0177] 4.4 After the seam cutting is completed, the movable blade 40 is reset; the air source is turned off, and the air intake 71 stops sucking air.

[0178] 4.5 The sewing machine performs normal sewing.

[0179] 4.6 When thread cutting is required at the end of sewing, the thread cutting drive motor 91 drives the first thread cutting cam 92 and the second thread cutting cam 93 to rotate. The post-sewing thread cutting drive section 922 of the first thread cutting cam 92 engages with the first roller 97, driving the movable blade 40 to rotate backward through the first transmission mechanism. Simultaneously, the variable diameter section of the second thread cutting cam 93 engages with the second roller 913, driving the auxiliary blade 30 to rotate forward through the second transmission mechanism. As the movable blade 40 rotates backward, the thread separating tip 44 first passes through the top thread loop, then the bottom thread and top thread on the side being cut slide into the separating groove 43 and are accommodated in the post-sewing thread receiving groove 49. Finally, the shared thread cutting edge 42 engages with the auxiliary blade 30 to cut the top thread and bottom thread. Afterward, the movable blade 40 and the auxiliary blade 30 return to their original positions.

[0180] 4.7 When the air source is turned on, the air intake 71 of the air suction device sucks up the bottom thread end 110, causing the bottom thread end 110 to tilt to the lower left.

[0181] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0182] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A method for controlling nest trimming in birds, characterized in that: The steps are as follows: S1. Configure a low-nest thread cutting mechanism, which includes an auxiliary blade (30), a movable blade (40) that can move toward or away from the auxiliary blade (30), and a thread clamping assembly. The movable blade (40) is provided with a starting thread cutting edge, a starting thread hook groove (41) that allows the needle (10) in the sewing machine to pass through, and a needle avoidance groove (45). S2. Before the sewing machine starts the first stitch, or during the process of the sewing machine needle (10) moving down, the movable knife (40) moves so that the starting stitch hook groove (41) is located directly below the needle (10); S3. The sewing machine needle (10) moves down to start the first stitch. The needle (10) passes through the starting stitch hook groove (41). Under the action of the rotary hook (20) in the sewing machine, the thread end on one side of the needle (10) is brought to the bottom of the movable knife (40). S4. The sewing machine starts sewing the first stitch. The needle (10) moves upward. After the needle (10) moves upward from the movable blade (40), the movable blade (40) moves so that the clearance groove (45) is directly below the needle (10). The movable blade (40) pulls out at least part of the thread end. At the same time, the thread clamping assembly clamps the thread end. S5. The sewing machine starts sewing the second stitch, the third stitch, ... up to the Nth stitch. The needle (10) moves up and down within the needle groove (45) and cuts the thread end during the process of starting the Nth stitch. N≥2. When the sewing machine starts sewing the Nth stitch, the needle (10) moves down from the clearance groove (45), the rotary hook (20) hooks the thread to form a thread loop, and the take-up lever in the sewing machine moves up to start taking in the thread; When the thread take-up lever moves up to the target position A, the movable blade (40) moves towards the auxiliary blade (30) until the starting seam cutting edge engages with the auxiliary blade (30) to cut off the thread end. The target position A is the non-highest point position of the thread take-up lever. S6. The thread take-up lever continues to move upward, pulling back the top thread below the seam material and tightening the bottom thread.

2. The method for controlling nest cutting as described in claim 1, characterized in that: The nest-cutting mechanism also includes a fixed suction pipe (70), which has a suction port (71) aligned with the movable blade (40) and / or the rotary hook (20). In step S3, the air intake (71) draws in air and picks up the thread end on one side of the needle (10) and the bottom thread end (110) on the rotary hook (20); In step S5, the cut ends of the face thread are collected through the air intake (71).

3. The method for controlling nest cutting as described in claim 2, characterized in that: The movable blade (40) is also provided with a thread-cutting edge after sewing, and the air inlet (71) is set along the axis of the rotary shuttle (20) in the sewing machine and toward the rotary shuttle (20), and the air inlet (71) is also set below the upper end of the rotary shuttle (20); the method for controlling thread cutting in bird nests also includes the following steps: S7. When the sewing is finished and the thread needs to be cut, the movable blade (40) moves towards the auxiliary blade (30). The movable blade (40) will bring the bottom thread and the top thread together to the auxiliary blade (30) until the thread cutting edge of the sewing cutter engages with the auxiliary blade (30) and cuts the top thread and the bottom thread. S8. The air intake (71) draws in air and picks up the bottom thread end (110) on the rotary hook (20), so that the bottom thread end (110) is angled downward and located on the path of the face thread loop.

4. The method for controlling nest cutting as described in claim 3, characterized in that: The starting seam cutting edge and the post-seam cutting edge are the same common cutting edge (42).

5. The method for controlling nest cutting as described in claim 3, characterized in that: The air intake (71) is located near the detachment side of the upper wire loop of the rotary shuttle (20).

6. The method for controlling nest cutting as described in claim 1, characterized in that: The nest-cutting mechanism also includes a fixedly installed wire pressing plate. The surface of the movable blade (40) is provided with a first wire clamping part (411), and the wire pressing plate is provided with a second wire clamping part. The first wire clamping part (411) and the second wire clamping part constitute a wire clamping assembly. In step S4, a clamping seam is formed between the first clamping part (411) and the second clamping part, and the end of the face thread is clamped in the clamping seam.

7. The method for controlling nest cutting as described in claim 1, characterized in that: The surface of the movable blade (40) is provided with a first wire clamping part (411), and the auxiliary blade (30) is provided with a third wire clamping part (31). The first wire clamping part (411) and the third wire clamping part (31) constitute a wire clamping assembly. In step S4, a clamping seam is formed between the first clamping part (411) and the third clamping part (31), and the end of the face thread is clamped in the clamping seam.

8. The method for controlling nest cutting as described in claim 1, characterized in that: The avoidance groove (45) is an empty area formed on the outer periphery of the movable blade (40).

9. The method for controlling nest cutting as described in claim 8, characterized in that: The avoidance groove (45) is located near the starting seam cutting edge. The outer edge of the movable knife (40) is provided with a transition surface (48) distributed between the avoidance groove (45) and the starting seam cutting edge. The transition surface (48) is a slope or a circular arc surface.

10. The method for controlling nest cutting as described in claim 1, characterized in that: The movable blade (40) is rotatably mounted below the sewing machine base plate (50), and the auxiliary blade (30) is fixedly mounted, or movably mounted below the sewing machine base plate (50), or rotatably mounted below the sewing machine base plate (50).

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