Sewing-starting thread trimming device and method for preventing shedding and reducing bird nests during sewing starting of sewing machine

Abstract

The invention provides a sewing machine start-sewing thread trimming device and method capable of preventing thread falling and reducing bird nests, the sewing machine start-sewing thread trimming device comprises a thread clamping piece, a movable cutter, a matched cutter and a movable cutter driving mechanism, the thread clamping piece and the movable cutter are arranged below a needle plate of the sewing machine, the movable cutter is provided with a movable cutter working part, the movable cutter working part is provided with a movable cutter through hole and a movable cutter blade, and the movable cutter through hole is communicated with the movable cutter blade. The movable cutter driving mechanism drives the movable cutter to move, so that the movable cutter working part is close to the matched cutter to shear threads or is separated from the matched cutter, the movable cutter through hole passes through the lower part of a needle plate hole of the needle plate, and the thread clamping piece is provided with a thread clamping working part which is matched with the movable cutter to clamp upper threads. And the thread clamping sheet driving mechanism is connected with the thread clamping sheet and can drive the thread clamping sheet to move, so that the thread clamping working part moves towards the matching cutter and passes through the lower part of the movable cutter through hole of the movable cutter.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and in particular to a sewing machine starting thread cutting device and method for preventing slippage and reducing bird nests. Background Technology

[0002] In the field of pattern sewing machines, the process of making the first stitch on the sewing material is called the start-up stitch. During the start-up stitch, there is a certain probability that the start-up stitch will fail if there is a free thread end at one end of the top thread. There are two situations where the start-up stitch fails: 1) The top thread end is too short and cannot catch the bottom thread, causing the subsequent stitches to fail and seriously affecting sewing production; 2) The top thread end is too long and will get tangled with the bottom thread, forming a bird's nest-like defect. This bird's nest-like defect affects the appearance and requires the sewing worker to manually repair it afterward, which is a tedious task.

[0003] An existing conventional structural solution for preventing seam opening and detachment is shown in the attached figure. Figure 1 To be continued Figure 3 As shown, it consists of a moving blade 01, a fixed blade 02, and a thread clamping plate 03. Its working principle is as follows: When the sewing machine starts its first stitch, the shuttle hook will fail to catch the thread, leaving a thread end below the needle plate hole. At this time, the through hole on the moving blade 01 aligns with the needle plate hole, as shown in the attached diagram. Figure 1 As shown. Then, the driving blade motion will cause the thread end to move, and when it moves to the attached... Figure 2 At the position shown, the moving blade 01 engages with the thread clamping plate 03, clamping the thread end in the middle to prevent the stitch from starting and unraveling. After the sewing machine performs its 2nd-3rd stitch, it drives the moving blade 01 to engage with the fixed blade 02 above, trimming the thread end, as shown in the attached diagram. Figure 3 As shown. The above structural scheme has the following disadvantages: 1) When clamping the thread, the thread ends other than the clamped part are not fixed and are easy to enter the thread loop, thus being wrapped in the fabric, increasing the process of picking out the thread ends by the sewing machine operator; 2) The fixed blade 02 is below the moving blade 01, and after cutting off the thread, the remaining thread ends are still very long; 3) By setting the spring 04 to keep the position of the clamping plate, the clamping effect of the thread ends with the moving blade can be ensured, but the spring 04 is easy to break, and the structure is unreliable. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a sewing machine starting thread cutting device and method for preventing slippage and reducing bird nests, which can effectively prevent the thread end from entering the thread loop and reduce the length of the thread end.

[0005] To achieve the above objectives, the present invention provides a sewing machine thread-cutting device for preventing thread slippage and reducing bird nests during sewing, comprising a thread clamping plate, a movable blade, a cooperating blade, and a movable blade driving mechanism. The thread clamping plate and the movable blade are both disposed below the needle plate of the sewing machine. The movable blade has a movable blade working part, which has a movable blade through hole and a movable blade edge. The movable blade driving mechanism drives the movable blade to move, causing the movable blade working part to approach the cooperating blade for thread cutting or to separate from the cooperating blade. The movable blade through hole passes below the needle plate hole of the needle plate. The invention also includes a thread clamping plate driving mechanism. The thread clamping plate has a thread-clamping working part for cooperating with the movable blade to clamp the thread. The thread clamping plate driving mechanism is connected to the thread clamping plate and can drive the thread clamping plate to move so that the thread-clamping working part moves towards the cooperating blade and passes below the movable blade through hole.

[0006] Furthermore, it also includes an air blowing mechanism, wherein the air blowing port of the air blowing mechanism blows air below the needle plate hole of the needle plate.

[0007] Furthermore, the air inlet and the mating knife are located on both sides of the needle plate hole, so that the gas blown out of the air inlet reaches the mating knife after passing below the needle plate hole.

[0008] Furthermore, the wire clamping plate driving mechanism includes a driven component for drivingly connecting the movable blade and the wire clamping plate. When the movable blade driving mechanism drives the movable blade's movable blade working part to approach the mating blade, it drives the driven component. The driven component drives the wire clamping plate to move the wire clamping working part toward the mating blade and pass through the movable blade's movable blade through hole.

[0009] Furthermore, the driven component includes a driven swing member, the wire clamping piece is fixedly installed on the driven swing member, the movable blade is provided with a first pushing part, and when the movable blade moves so that the working part of the movable blade approaches the mating blade, the first pushing part can push the driven swing member to rotate and cause the wire clamping part to move toward the mating blade.

[0010] Furthermore, the movable blade is provided with a second pushing part. When the movable blade moves and the working part of the movable blade moves away from the mating blade, the second pushing part can push the driven swing member to rotate and move the clamping part away from the mating blade.

[0011] Furthermore, the wire clamping plate driving mechanism includes a return spring connected to the wire clamping plate, the elastic force of which is used to drive the wire clamping plate to move and return the wire clamping working part to the initial position away from the mating knife.

[0012] Furthermore, when the moving part of the movable blade moves to the mating blade, it is located below the mating blade.

[0013] Furthermore, it also includes an air intake mechanism, the air intake of which faces the mating blade of the mating knife.

[0014] This invention also provides a sewing machine starting thread cutting method to prevent slippage and reduce bird nests, which uses the above-mentioned starting thread cutting device and includes the following steps:

[0015] S1. Before starting to sew, the moving knife through hole of the movable knife is located below and aligned with the needle plate hole of the needle plate. When starting the first stitch, the sewing machine needle drives the thread end through the needle plate hole and the moving knife through hole.

[0016] S2. The moving blade moves the moving blade working part toward the mating blade, and the wire clamping plate drive mechanism drives the wire clamping plate to move, so that the wire clamping working part moves toward the mating blade and passes below the moving blade through hole of the moving blade, pushing the top thread end toward the mating blade side, and clamping the top thread end between the moving blade working part and the wire clamping working part at the bottom of the moving blade through hole.

[0017] S3. The sewing machine then performs several more stitches.

[0018] S4. The movement of the movable blade brings the working part of the movable blade close to the mating blade. The movable blade and the mating blade engage to cut off the end of the surface thread, and the surface thread disengages from the movable blade and the mating blade.

[0019] As described above, the seam-starting and thread-cutting device and method of the present invention have the following beneficial effects:

[0020] 1. It can ensure that the thread ends of the top thread do not enter the thread loop when starting to sew. By setting up a thread clamping plate to guide the thread, plus the assistance of a blower, it can ensure that the thread ends of various thicknesses of top thread do not enter the thread loop when they are clamped, thus avoiding rework.

[0021] 2. By shortening the thread ends and placing the matching knife above the movable knife, the distance between the matching knife and the pinhole plate is short, thus achieving short thread ends and making the resulting bird's nest smaller, making it easier for the machinist to pick out and trim.

[0022] 3. By setting up an air suction mechanism, the air intake is located at the point where the wire clamping plate and the movable blade cut the wire, which can promptly suck away the cut wire ends and prevent the wire ends from accumulating and causing the mechanism to jam.

[0023] 4. The mechanism is reliable. The mechanical force of the moving blade itself drives the driven swing arm, which in turn drives the wire clamping plate mechanism. This simplifies the mechanism and eliminates the need for springs, thereby increasing the service life and maintenance frequency of the mechanism. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the working state of the existing anti-loosening structure.

[0025] Figure 2 This is a schematic diagram of the second working state of the existing anti-detachment structure.

[0026] Figure 3This is a schematic diagram of the working state three of the existing anti-loosening structure.

[0027] Figure 4 This is a schematic diagram of the structure of the movable blade, the cooperating blade, the clamping plate, and the driven swing member in the thread-cutting device of the present invention.

[0028] Figure 5 for Figure 4 Top view.

[0029] Figure 6 for Figure 4 A bottom view.

[0030] Figure 7 This is a schematic diagram of the structure of the clamping plate and the driven pendulum in this invention.

[0031] Figure 8 This is a schematic diagram of the working state of the sewing and thread cutting device of the present invention.

[0032] Figure 9 This is a schematic diagram of the second working state of the sewing and thread-cutting device of the present invention.

[0033] Figure 10 This is a schematic diagram of the third working state of the sewing and thread-cutting device of the present invention.

[0034] Figure 11 This is a schematic diagram of the fourth working state of the sewing and thread cutting device of the present invention.

[0035] Explanation of icon numbers:

[0036] 01-Moving blade, 02-Fixed blade, 03-Wire clamping plate, 04-Spring.

[0037] 10-Needle plate, 11-Needle plate hole, 20-Moving knife, 21-Moving knife working part, 22-Moving knife through hole, 23-Moving knife blade, 24-First guide slope, 25-Moving knife rotating shaft, 26-First push part, 27-Second push part, 30-Matching knife, 31-Matching blade, 32-Smooth curved surface, 40-Wire clamping piece, 41-Wire clamping working part, 42-Second guide slope, 50-Driven swing piece, 51-Swing piece rotating shaft, 60-Blowing pipe, 61-Blowing port, 70-Suction pipe, 71-Suction port. Detailed Implementation

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] See Figures 4 to 11This invention provides a sewing machine thread-cutting device for preventing slippage and reducing bird nests during sewing, including a thread clamping plate 40, a movable blade 20, a cooperating blade 30, and a moving blade driving mechanism. The thread clamping plate 40 and the movable blade 20 are both located below the needle plate 10 of the sewing machine. The movable blade 20 has a moving blade working part 21, which has a moving blade through hole 22 and a moving blade edge 23. The moving blade working part 21 is used to drive the thread, and cooperate with the thread clamping plate 40 and the cooperating blade 30 to clamp and cut the thread. The moving blade driving mechanism drives the movable blade 20 to move, causing the moving blade working part 21 to move close to the cooperating blade 30 to cut the thread or to separate from the cooperating blade 30. The moving blade through hole 22 passes below the needle plate hole 11 of the needle plate 10. The cooperating blade 30 can be a fixed blade or a movable blade that can move towards the movable blade 20, as long as it can cooperate with the movable blade 20 to cut the thread. The improvement of the present invention is that it also includes a wire clamping plate driving mechanism. The wire clamping plate 40 has a wire clamping working part 41 for cooperating with the movable blade 20 to clamp the surface wire. The wire clamping plate driving mechanism is connected to the wire clamping plate 40 and can drive the wire clamping plate 40 to move so that the wire clamping working part 41 moves toward the cooperating blade 30 and passes below the movable blade through hole 22 of the movable blade 20.

[0043] The seam-starting and thread-cutting device involved in this invention can achieve two functions: preventing seam slippage and reducing bird nests. Its main working principle is as follows: Before starting the seam, see... Figure 8 The movable blade 20's movable blade through hole 22 is located below the needle plate hole 11 of the needle plate 10 and aligned with it. At this time, the thread clamping working part 41 of the thread clamping plate 40 is away from the mating blade 30. Then, the first stitch is started, and the sewing machine needle drives the thread end through the needle plate hole 11 and the movable blade through hole 22; the movable blade 20 moves, causing the movable blade working part 21 to move towards the mating blade 30, the movable blade through hole 22 drives the thread closer to the mating blade 30, and the thread clamping plate drive mechanism drives the thread clamping plate 40 to move, causing the thread clamping working part 41 to move towards the mating blade 30. See [link to relevant documentation]. Figure 9 The clamping part 41 passes below the moving knife through hole 22 of the movable knife 20, pushing the thread end towards the side where the mating knife 30 is located. This ensures that the thread end is clamped between the moving knife working part 21 and the clamping part 41 at the lower side of the moving knife through hole 22. See [link / reference] Figure 10 This ensures that the thread end does not enter the thread loop, avoiding rework. The sewing machine then performs several more stitches (e.g., the 2nd-3rd stitches). After completion, the movable blade 20 continues to move, causing the moving blade working part 21 to move closer to the mating blade 30. The movable blade 20 and the mating blade 30 engage and cut the thread end, thus shortening the thread end and reducing bird's nest formation. The thread then disengages from the movable blade 20 and the mating blade 30. The movable blade 20, the thread clamping plate 40, and other related components remain in this position until the sewing is completed and they return to their original positions.

[0044] See Figures 4 to 11The present invention will be further described below with reference to a specific embodiment:

[0045] In this embodiment, see Figure 8 As a preferred design, the thread-cutting device also includes an air-blowing mechanism. The air-blowing mechanism's air-blowing port 61 blows air downwards towards the needle plate hole 11 of the needle plate 10. Specifically, the air-blowing mechanism can be extended below the needle plate 10 via an air-blowing pipe 60, with the port of the air-blowing pipe 60 forming the air-blowing port 61. Furthermore, the air-blowing port 61 and the mating knife 30 are located on opposite sides of the needle plate hole 11, allowing the air blown out by the air-blowing port 61 to reach the mating knife 30 after passing below the needle plate hole 11. By setting up the air-blowing mechanism and the air-blowing port 61, after the first stitch is started, the needle drives the thread end through the needle plate hole 11 and the moving knife through hole 22. At this time, the air-blowing port 61 begins to blow air, moving the thread end towards the side where the mating knife 30 is located, further ensuring that the thread end does not enter the thread loop.

[0046] In this embodiment, see Figure 8 As a preferred design, an air suction mechanism is also included. The air suction port of the air suction mechanism faces the mating blade 31 of the mating knife 30, specifically close to the position where the clamping piece 40 and the movable knife 20 separate the top thread. The air suction mechanism can be extended into the lower part of the needle plate 10 through the air suction pipe 70, with the end of the air suction pipe 70 forming the air suction port 71. Furthermore, the blowing port 61 and the air suction port 71 can be located on both sides of the mating blade 31 of the mating knife 30, that is, the blowing port 61 blows air towards the side where the air suction port 71 is located. By setting up the air suction mechanism, when the movable knife 20 and the mating knife 30 engage and cut the top thread end, the air suction mechanism works to promptly suck away the cut thread end, avoiding the accumulation of thread ends and preventing the mechanism from jamming.

[0047] In this embodiment, see Figure 4 , Figure 5 , Figure 6 and Figure 8 As a preferred design, the movable blade 20 is rotatably mounted on the lower side of the needle plate 10 via a movable blade shaft 25. A movable blade drive mechanism drives the movable blade 20 to rotate; this drive mechanism can employ various suitable existing designs. The thread clamping plate 40 is also rotatably mounted on the lower side of the needle plate 10. In other embodiments, the movable blade 20 and the thread clamping plate 40 can also employ other forms of motion, moving along a straight line or a curve.

[0048] In this embodiment, see Figure 4 , Figure 5 , Figure 6 and Figure 7As a preferred design, the wire clamping plate drive mechanism includes a driven component for drivingly connecting the movable blade 20 and the wire clamping plate 40. When the movable blade drive mechanism drives the movable blade 20's movable blade working part 21 to approach the mating blade 30, it drives the driven component, which in turn drives the wire clamping plate 40, causing the wire clamping working part 41 to move toward the mating blade 30 and pass through the movable blade through hole 22 of the movable blade 20. That is, a driven method is used, where the movement of the movable blade 20 drives the movement of the wire clamping plate 40. The wire clamping plate drive mechanism may also include a return spring (not shown in the figures) directly or indirectly connected to the wire clamping plate 40, providing elastic force to drive the wire clamping plate 40 to return the wire clamping working part 41 to its initial position away from the mating blade 30. Furthermore, when the moving blade drive mechanism drives the moving blade 20's moving blade working part 21 away from the mating blade 30, it also drives the driven component. The driven component then drives the clamping plate 40 to move the clamping working part 41 away from the mating blade 30. In other words, the reset of the clamping plate 40 is driven by the reset movement of the moving blade 20. This overcomes the contact friction between the clamping plate 40 and the surrounding components such as the fixed and moving blades, ensuring that the clamping plate 40 can smoothly reset. In this case, a reset spring is not required. Using this driven method for the clamping plate 40 simplifies the mechanism, eliminates the need for an additional power source, and eliminates the need for a spring, thereby increasing the mechanism's service life and maintenance frequency.

[0049] In this embodiment, further, see... Figure 4 , Figure 5 , Figure 6 and Figure 7 As a preferred design, the driven component includes a driven swing member 50, which is rotatably mounted on the lower side of the needle plate 10 via a swing member pivot 51. A clamping piece 40 is fixedly mounted on the driven swing member 50 and rotates with it. The movable blade 20 has a first pushing part 26 and a second pushing part 27. When the movable blade 20 rotates until the movable blade working part 21 approaches the mating blade 30, the first pushing part 26 can push the driven swing member 50 to rotate, causing the clamping piece 41 to move towards the mating blade 30. By setting the structural dimensions and motion relationship dimensions of the movable blade 20, the driven swing member 50, and the clamping piece 40, the movement speed of the clamping piece 41 is greater than the speed of the movable blade working part 21 when the movable blade 20 pushes the driven swing member 50 and the clamping piece 40 to rotate. This allows the clamping piece 41 to pass through the movable blade through hole 22 and push the thread in the movable blade through hole 22 towards the mating blade 30. When the movable blade 20 rotates until the moving blade working part 21 moves away from the mating blade 30, the second pushing part 27 can also push the driven swing member 50 to rotate, and cause the wire clamping working part 41 to move away from the mating blade 30, so that the wire clamping piece 40 can be smoothly reset. In other embodiments, the driven component can also adopt other existing suitable structures that can link the movement of the wire clamping piece 40 with the movable blade 20, and as a driven member, can achieve the above-mentioned movement.

[0050] In addition to using a driven mode, where the movement of the movable blade 20 drives the wire clamping plate 40, the wire clamping plate driving mechanism of this invention can also use an active mode, where a motor or other driving source is used to actively drive the wire clamping plate 40 to rotate, which, in conjunction with the movement of the movable blade 20, achieves the pushing, clamping, and cutting of the wire end.

[0051] In this embodiment, see Figure 4 , Figure 5 and Figure 6 As a preferred design, when the moving blade working part 21 of the movable blade 20 moves to the mating blade 30, it is located below the mating blade 30. The mating blade 31 of the mating blade 30 is located above the moving blade working part 21 and the moving blade through hole 22. This makes the distance between the mating blade 30 and the lower end of the needle plate hole 11 shorter, thus achieving short thread ends and making the bird's nest smaller, which is easier for the machine operator to pick out and trim.

[0052] In this embodiment, see Figure 4 , Figure 5 and Figure 6 The movable through hole 22 in the movable blade 20 is an oblique hole, meaning its axis is inclined. The lower end of the movable through hole 22 is inclined away from the mating blade 30 relative to its upper end. In other words, when the movable blade 20 is in its initial position, the upper end of the movable through hole 22 is closer to the mating blade 30 than its lower end. The portion of the upper end of the movable through hole 22 away from the mating blade 30 forms the movable blade cutting edge 23. The upper surface of the movable blade working part 21 of the movable blade 20 is provided with a first guide slope 24. The upper end of the movable through hole 22 is located in the first guide slope 24. The first guide slope 24 gradually decreases along the direction of movement of the movable blade working part 21 towards the mating blade 30. It can be a sloping plane or a curved surface. When the movable blade working part 21 approaches the mating blade 30, the first guide slope 24 inserts into the lower side of the mating blade 30, thereby avoiding collision problems. Furthermore, a mating blade 31 is formed on the bottom edge of the mating blade 30 near the needle plate hole 11, which can then effectively engage with the moving blade 23 at the upper end of the moving blade through hole 22 to cut the wire. A smooth curved surface 32 is formed on the upper surface of the mating blade 30 near the upper side of the mating blade 31 to avoid the formation of sharp sides and the problem of cutting the surface line.

[0053] In this embodiment, see Figure 4 and Figure 7 The upper surface of the thread clamping working part 41 of the thread clamping piece 40 is also provided with a second guide slope 42, which gradually decreases in height along the movement direction of the thread clamping working part 41 away from the mating knife 30. After the movable knife 20 and the mating knife 30 engage and cut the thread end, and before resetting after sewing, see [reference needed]. Figure 11When the clamping plate 40 moves, the clamping working part 41 moves away from the mating knife 30. At this time, the second guide slope 42 enters the lower side of the moving knife working part 21 of the movable knife 20 and guides the moving knife working part 21 to move along the second guide slope 42, thereby avoiding interference problems and ensuring that the clamping plate 40 can be smoothly reset.

[0054] This invention also provides a sewing machine starting thread cutting method to prevent slippage and reduce bird nests, which uses the above-mentioned starting thread cutting device and includes the following steps:

[0055] S1. Before starting the seam, see Figure 8 The thread-cutting device is in its initial position, with the movable blade through-hole 22 of the movable blade 20 positioned below and aligned with the needle plate hole 11 of the needle plate 10. At this time, the thread-clamping working part 41 of the thread clamping piece 40 and the cooperating blade 30 are located on both sides of the needle plate hole 11, respectively. Then, the first stitch is started, and the sewing machine needle drives the thread end through the needle plate hole 11 and the movable blade through-hole 22. In the embodiment, preferably, after the needle drives the thread end through the needle plate hole 11 and the movable blade through-hole 22, the air blowing port 61 of the air blowing mechanism blows air towards the area below the needle plate hole 11 and the side where the cooperating blade 30 is located, blowing the thread end towards the side where the cooperating blade 30 is located, further ensuring that the thread end can be prevented from entering the thread loop.

[0056] S2. The movement of the movable blade 20 causes the movable blade working part 21 to move toward the mating blade 30, and the wire clamping plate driving mechanism drives the wire clamping plate 40 to move, causing the wire clamping working part 41 to move toward the mating blade 30 and pass below the movable blade through hole 22 of the movable blade 20, pushing the head of the top thread toward the side where the mating blade 30 is located, and clamping the head of the top thread between the movable blade working part 21 and the wire clamping working part 41 at the lower side of the movable blade through hole 22.

[0057] In an embodiment, preferably, see [link to embodiment]. Figures 8 to 9 To illustrate the process, from a downward view below the needle plate 10, the movable blade 20 rotates counterclockwise, and the moving blade working part 21 gradually approaches the mating blade 30 and moves away from below the needle plate hole 11. The moving blade through hole 22 causes the thread to approach the mating blade 30. When the movable blade 20 rotates counterclockwise, it pushes the driven rocker arm 50 to rotate counterclockwise through the first pushing part 26, causing the thread clamping piece 40 to rotate counterclockwise. Furthermore, the movement speed of the thread clamping working part 41 is greater than that of the moving blade working part 21. The thread clamping working part 41 passes under the moving blade through hole 22. (See below for more details.) Figure 10 This pushes the thread end toward the side where the mating knife 30 is located, ensuring that the thread end is 100% clamped at the end of the moving knife through hole 22.

[0058] S3. The sewing machine then performs several more stitches, usually the 2nd or 3rd stitch. At this time, the movable blade 20 and the thread clamping plate 40 have left the needle plate hole 11 and will not affect the movement of the needle.

[0059] S4. The movement of the movable blade 20 causes the working part 21 of the movable blade to move closer to the mating blade 30. The movable blade 20 and the mating blade 30 engage and cut off the end of the surface thread, and the surface thread disengages from the movable blade 20 and the mating blade 30. In this embodiment, preferably, see... Figures 10 to 11 The movable blade 20 continues to rotate counterclockwise, pushing the driven ornament 50 and the thread clamping plate 40 to rotate counterclockwise as well. The moving blade 23 and the mating blade 31 engage, cutting off the thread end. The thread clamping plate 40 then separates from the movable blade 20, allowing the thread to unlatch. At this point, the suction port 71 of the suction pipe 70 opens, sucking away the cut thread end. The movable blade 20, thread clamping plate 40, and related components remain in this position until normal sewing is completed, at which point they will return to their original positions. During the subsequent reset process, the movable blade drive mechanism drives the movable blade 20 to rotate clockwise, while the second pushing part 27 of the movable blade 20 pushes the driven ornament 50 to rotate clockwise, and the thread clamping plate 40 also rotates clockwise, ultimately returning to its original position. Figure 8 The initial position is shown.

[0060] The seam-starting and thread-cutting device and method of the present invention have the following beneficial effects:

[0061] 1. It can ensure that the thread ends of the top thread do not enter the thread loop when starting to sew. By setting the thread clamping plate 40 to guide the thread, plus the assistance of blower, it can ensure that the thread ends of the top thread of various thicknesses do not enter the thread loop when they are clamped, thus avoiding rework.

[0062] 2. By shortening the thread ends and placing the matching knife 30 above the movable knife 20, the distance between the matching knife 30 and the pinhole plate is short, thus achieving short thread ends and making the resulting bird's nest smaller, which is easier for the machinist to pick out and trim.

[0063] 3. By setting up an air suction mechanism, the air suction port 71 is located at the point where the wire clamping plate 40 and the movable blade 20 cut the wire and remove the cut wire ends in time, thus preventing the wire ends from accumulating and causing the mechanism to jam.

[0064] 4. The mechanism is reliable. The mechanical force of the movable blade 20 itself drives the driven swing arm, which in turn drives the clamping plate 40 mechanism. The mechanism is simplified and does not require the use of springs, thereby increasing the service life and maintenance frequency of the mechanism.

[0065] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0066] 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 sewing machine thread-cutting device for preventing slippage and reducing bird nests during sewing, comprising a thread clamping plate (40), a movable blade (20), a matching blade (30), and a movable blade driving mechanism, wherein the thread clamping plate (40) and the movable blade (20) are both disposed below the needle plate (10) of the sewing machine, the movable blade (20) is provided with a movable blade working part (21), the movable blade working part (21) is provided with a movable blade through hole (22) and a movable blade cutting edge (23), the movable blade driving mechanism drives the movable blade (20) to move, so that the movable blade working part (21) is close to the matching blade (30) to cut the thread or separates from the matching blade (30), and the movable blade through hole (22) passes below the needle plate hole (11) of the needle plate (10), characterized in that: It also includes a wire clamping plate driving mechanism. The wire clamping plate (40) has a wire clamping working part (41) for cooperating with the movable blade (20) to clamp the surface wire. The wire clamping plate driving mechanism is connected to the wire clamping plate (40) and can drive the wire clamping plate (40) to move so that the wire clamping working part (41) moves toward the cooperating blade (30) and passes below the moving blade through hole (22) of the movable blade (20).

2. The seam-starting and thread-cutting device according to claim 1, characterized in that: It also includes an air blowing mechanism, wherein the air blowing port (61) of the air blowing mechanism blows air below the needle plate hole (11) of the needle plate (10).

3. The seam-starting and thread-cutting device according to claim 2, characterized in that: The air inlet (61) and the mating knife (30) are located on both sides of the needle plate hole (11), so that the gas blown out by the air inlet (61) passes under the needle plate hole (11) and reaches the mating knife (30).

4. The seam-starting and thread-cutting device according to claim 1, characterized in that: The wire clamping plate driving mechanism includes a driven component for driving the movable blade (20) and the wire clamping plate (40) together. When the movable blade driving mechanism drives the movable blade working part (21) of the movable blade (20) to approach the mating blade (30), it drives the driven component. The driven component drives the wire clamping plate (40) to make the wire clamping working part (41) move toward the mating blade (30) and pass through the movable blade through hole (22) of the movable blade (20).

5. The seam-starting and thread-cutting device according to claim 4, characterized in that: The driven component includes a driven swing member (50), the wire clamping piece (40) is fixedly installed on the driven swing member (50), the movable blade (20) is provided with a first pushing part (26), when the movable blade (20) moves and the movable blade working part (21) approaches the mating blade (30), the first pushing part (26) can push the driven swing member (50) to rotate and make the wire clamping working part (41) move toward the mating blade (30).

6. The seam-starting and thread-cutting device according to claim 5, characterized in that: The movable blade (20) is provided with a second pushing part (27). When the movable blade (20) moves and the moving blade working part (21) moves away from the cooperating blade (30), the second pushing part (27) can push the driven swing part (50) to rotate and make the clamping wire working part (41) move away from the cooperating blade (30).

7. The seam-starting and thread-cutting device according to claim 1, characterized in that: The wire clamping plate driving mechanism includes a return spring connected to the wire clamping plate (40). The spring force of the return spring is used to drive the wire clamping plate (40) to move so that the wire clamping working part (41) returns to the initial position away from the mating knife (30).

8. The seam-starting and thread-cutting device according to claim 1, characterized in that: When the moving blade (20) moves to the mating blade (30), the moving blade working part (21) is located below the mating blade (30).

9. The seam-starting and thread-cutting device according to claim 1, characterized in that: It also includes an air intake mechanism, the air intake of which faces the mating blade (31) of the mating blade (30).

10. A sewing machine starting stitch thread cutting method to prevent slippage and reduce bird nests, characterized in that: The process, performed using the seam-starting and thread-cutting device as described in any one of claims 1 to 9, includes the following steps: S1. Before starting to sew, the moving knife through hole (22) of the moving knife (20) is located below and aligned with the needle plate hole (11) of the needle plate (10). When starting to sew the first stitch, the sewing machine needle drives the thread end through the needle plate hole (11) and the moving knife through hole (22). S2. The movement of the movable blade (20) causes the movable blade working part (21) to move toward the mating blade (30), and the wire clamping plate driving mechanism drives the wire clamping plate (40) to move, causing the wire clamping working part (41) to move toward the mating blade (30) and pass below the movable blade through hole (22) of the movable blade (20), pushing the head of the top thread toward the mating blade (30) and clamping the head of the top thread between the movable blade working part (21) and the wire clamping working part (41) at the lower side of the movable blade through hole (22); S3. The sewing machine then performs several more stitches. S4. The movement of the movable blade (20) causes the working part (21) of the movable blade to approach the mating blade (30). The movable blade (20) and the mating blade (30) engage to cut off the end of the face thread, and the face thread is disengaged from the movable blade (20) and the mating blade (30).

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