A sewing thread trimming method

Abstract

The present application provides a sewing thread cutting method, which belongs to the technical field of sewing machines. The present application solves the problem of residual thread on the fabric during sewing of the existing sewing machine. The sewing thread cutting method comprises the following steps: S1, the thread guide hole is located directly below the needle; S2, the needle goes down to drive the thread to pass through the thread guide hole; S3, the main thread cutting knife rotates in the clockwise direction along the rotating hook and moves to the right to approach the auxiliary thread cutting knife; S4, the main blade of the main thread cutting knife and the auxiliary blade of the auxiliary thread cutting knife cut the thread end at the position below the needle; S5, the main thread cutting knife rotates to the left side of the needle, and the auxiliary thread cutting knife rotates to the right side of the needle; S6, the main blade and the auxiliary blade cut the bobbin thread and the thread on the fabric at the position below the needle. The present sewing thread cutting method has the advantage of stable thread cutting effect.

Description

Technical Field

[0001] This invention belongs to the field of sewing machine technology and relates to a sewing thread cutting method. Background Technology

[0002] As a core processing equipment in the textile, clothing, and leather goods industries, sewing machines mainly use the cooperation of the needle and the rotary hook to drive the interlacing of the top and bottom threads, thereby achieving continuous sewing of multiple layers of fabric. They are widely used in various light industrial manufacturing scenarios such as clothing sewing, home textile processing, and bag making.

[0003] In the fabric sewing industry, existing sewing machines generate excess thread ends during both the initial and final stitching stages. If these ends are not effectively removed, they can lead to numerous product quality issues and production problems. Under conventional sewing processes, after a single thread trimming and reset, a certain length of top thread remains at the needle and presser foot, and bottom thread remains at the bottom of the rotary hook. When the machine starts the initial stitching operation, these residual top and bottom thread ends easily entangle and accumulate on the fabric's underside, forming what is commonly known in the industry as a "bird's nest" of thread. This not only causes bulges and wrinkles in the sewn area, damaging the product's smoothness, but also leads to loose stitches and misaligned stitches, significantly reducing the strength of the seam. Subsequent use is prone to problems such as unraveling and cracking at the initial stitch, failing to meet the high-quality sewing requirements of mid-to-high-end garments and precision fabric products. In the final sewing stage, if the remaining long threads are left directly after sewing, it will cause the fabric surface to be messy with threads, requiring additional processing later. At the same time, long threads are prone to snagging and abrasion, affecting the product's lifespan and overall texture.

[0004] Therefore, there is an urgent need to develop a sewing machine thread trimming technology that can precisely remove thread ends in order to solve the various drawbacks of existing technologies and improve the overall quality and production efficiency of fabric sewing. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a sewing thread trimming method that solves the problem of residual thread ends on the fabric during sewing using existing sewing machines.

[0006] The objective of this invention can be achieved through the following technical solutions: A sewing thread cutting method employs a thread cutting mechanism, the thread cutting mechanism comprising a main thread cutter and an auxiliary thread cutter, both located above a rotary hook in a sewing machine and capable of circular motion around the hook. The main thread cutter has a main cutting edge, a thread guide hole, and a thread separating section, and the auxiliary thread cutter has an auxiliary cutting edge. The sewing thread cutting method is characterized by the following: S1. The thread guide hole of the main thread cutter is located directly below the sewing machine needle. At this time, the main cutting edge is located on the left side of the needle, and the thread separating part and the auxiliary thread cutter are both located on the right side of the needle. S2. The needle moves downward, driving the thread through the thread guide hole, and the rotary hook moves the free end of the thread to below the main thread cutter, so that the thread passes through the thread guide hole. S3. After the needle moves upward and disengages from the main thread cutter, the main thread cutter rotates clockwise around the shuttle and moves to the right towards the auxiliary thread cutter until the main cutting edge, thread guide hole, and thread divider on the main thread cutter are all located on the right side of the needle, offset from the position directly below the needle. S4. After the needle has sewn several stitches, both the main thread cutter and the auxiliary thread cutter rotate counterclockwise to the left around the shuttle. The main cutting edge of the main thread cutter and the auxiliary cutting edge of the auxiliary thread cutter cut off the thread ends below the needle. S5. The main thread cutter continues to rotate counterclockwise around the rotary hook to the left side of the needle, and the auxiliary thread cutter rotates clockwise back to the right side of the needle. At this time, the thread separating part is located on the far right of the main thread cutter. S6. After sewing is completed, the main thread cutter rotates clockwise to the right and the thread separating part separates the thread. The auxiliary thread cutter rotates counterclockwise to the left and the main and auxiliary blades cut the bottom and top threads attached to the sewing material below the needle. S7. Rotate the main wire cutter and the auxiliary wire cutter to their initial positions.

[0007] This sewing thread cutting method can first cut off the top thread during the initial sewing stage, and then cut off the bottom and top threads remaining in the fabric after the sewing is completely finished. The entire thread cutting action can be automatically completed by the drive unit driving the main thread cutter and the auxiliary thread cutter. The thread cutting effect is stable and can effectively avoid the influence of thread residue on the sewing.

[0008] In this sewing thread-cutting method, both thread-cutting actions are completed below the needle, ensuring that the cut thread ends are sufficiently short and avoiding quality issues caused by residual thread. Furthermore, during both cutting actions, the main and auxiliary thread cutters move in the same direction from the start of their movement until the thread end is cut, without reversing direction. This minimizes the time required for the cutting action and improves efficiency. Especially in the thread-cutting action after sewing is completed, since the thread separating section is located on the far right of the main thread cutter, the thread separating is completed simultaneously with the main thread cutter's rightward turn, eliminating unnecessary movements and further ensuring a sufficiently short cutting time.

[0009] In the above-described sewing thread cutting method, the thread cutting mechanism further includes a thread pressing plate. In step S3, after the main thread cutting blade rotates clockwise around the rotary hook and moves to the right towards the auxiliary thread cutting blade, the thread pressing plate and the main thread cutting blade clamp the top thread. By clamping the top thread with the thread pressing plate and the main thread cutting blade, the top thread will not come out of the thread guide hole when the needle sews several stitches in step S4, ensuring the stability of the top thread position during subsequent thread cutting, and thus enabling accurate cutting of the top thread.

[0010] In the above-described sewing thread cutting method, in step S3, when the pressure plate and the main thread cutter clamp the top thread, the main cutting edge is located between the auxiliary cutting edge and the needle. When the top thread is clamped, the main thread cutter and the auxiliary thread cutter do not engage, preventing the top thread from being accidentally cut and ensuring the stability of the top thread clamping, thereby ensuring the stability and accuracy of the thread cutting.

[0011] In the above-described sewing thread-cutting method, in step S4, both the main thread-cutting knife and the auxiliary thread-cutting knife rotate counterclockwise to the left around the rotary hook, with the auxiliary thread-cutting knife rotating faster than the main thread-cutting knife. Because the distance between the auxiliary blade and the bottom of the needle is greater than the distance between the main blade and the bottom of the needle, the auxiliary blade needs to be moved closer to the main blade by alternating between fast and slow movements of the auxiliary and main thread-cutting knives, thereby achieving the thread-cutting action below the needle.

[0012] In the aforementioned sewing thread cutting method, the thread cutting mechanism further includes a suction nozzle. In step S4, when both the main thread cutter and the auxiliary thread cutter rotate counterclockwise to the left around the rotary hook, the suction nozzle draws the thread end of the top thread into the nozzle. As the main and auxiliary thread cutters rotate to the left, the top thread disengages from the clamping plate, and the suction nozzle draws it in, stabilizing its position and providing sufficient tension during cutting to ensure effective thread cutting.

[0013] In the above-mentioned sewing thread cutting method, in step S7, the main thread cutter and the auxiliary thread cutter are rotated to their initial positions. The thread guide hole of the main thread cutter is located directly below the sewing machine needle, the main cutting edge is located on the left side of the needle, and the thread separating part and the auxiliary thread cutter are both located on the right side of the needle.

[0014] Compared with existing technologies, this sewing thread cutting method has the following advantages: 1. Both thread-cutting actions are completed below the needle, ensuring that the cut thread ends are short enough to avoid quality issues caused by thread residue.

[0015] 2. During the two thread-cutting actions, the main thread-cutting blade and the auxiliary thread-cutting blade move in one direction from the start of the action to the cutting of the thread end, without turning back, which minimizes the time required to complete the thread-cutting action and improves the thread-cutting efficiency.

[0016] 3. During the thread-cutting action after sewing is completed, since the thread separating part is located on the far right of the main thread cutter, the thread separating is completed simultaneously as the main thread cutter turns to the right to cut the thread, without any extra actions, further ensuring a sufficiently short thread-cutting time. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the wire-cutting mechanism.

[0018] Figure 2This is a schematic diagram of the main wire-cutting blade in the wire-cutting structure.

[0019] Figure 3 This is a schematic diagram of the auxiliary wire-cutting blade in the wire-cutting structure.

[0020] Figure 4 This is a structural diagram of step S1 in this sewing and thread-cutting method.

[0021] Figure 5 This is a structural diagram of step S2 in this sewing and thread-cutting method.

[0022] Figure 6 This is a structural diagram of step S3 in this sewing and thread-cutting method.

[0023] Figure 7 This is a structural diagram of step S4 in this sewing and thread-cutting method.

[0024] Figure 8 This is a structural diagram of step S5 in this sewing and thread-cutting method.

[0025] Figure 9 This is a structural diagram of step S6 in this sewing and thread-cutting method.

[0026] Figure 10 This is a flowchart of the sewing and thread-cutting method.

[0027] In the diagram, 1. Rotary hook; 2. Main thread cutter; 2a. Main cutting edge; 2b. Thread guide hole; 2c. Thread separating part; 2d. Thread guide groove; 2e. Thread hook groove; 3. Auxiliary thread cutter; 3a. Auxiliary cutting edge; 4. Needle; 5. Thread pressing plate; 6. Suction nozzle. Detailed Implementation

[0028] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments.

[0029] like Figure 1As shown, the thread-cutting mechanism includes two annular connecting frames, a main thread cutter 2, an auxiliary thread cutter 3, a pressure plate 5, and a suction nozzle 6. Both connecting frames are fitted onto the outside of the sewing machine shuttle 1 and are distributed along the front-to-back direction. Each connecting frame has two protruding connecting parts on its outer side. The main thread cutter 2 and the auxiliary thread cutter 3 are respectively fixed to the connecting parts of the two connecting frames, and both are positioned above the shuttle 1 after fixing. The other connecting part of the two connecting frames is connected to the output ends of two drive motors via several connecting rods, and the two drive motors drive the two connecting frames to rotate circumferentially around the shuttle 1. The pressure plate 5 is fixed below the sewing machine table and has a pressure part that can abut against the upper side of the main thread cutter 2. The suction nozzle 6 can be connected to the suction motor through a pipe. By creating negative pressure inside the pipe, the suction nozzle 6 can suck away the thread. The port of the suction nozzle 6 is close to the thread pressing part of the thread pressing piece 5, and the two are arranged adjacent to each other.

[0030] like Figure 2 As shown, the main wire cutter 2 is curved into an arc-shaped sheet. A connection hole for fastening to the connecting frame is provided at the rear. A circular cutting hole is provided through the front of the main wire cutter 2, with a main cutting edge 2a on the top left side of the circular cutting hole. A protruding section protrudes to the right on the right side of the front of the main wire cutter 2, with a circular wire guide hole 2b through it. A long, narrow wire guide groove 2d connecting the wire guide hole 2b and the cutting hole is provided at the top of the main wire cutter 2. A recessed, long, narrow wire hook groove 2e is provided on the front side of the main wire cutter 2, with one end of the hook groove 2e extending to the wire guide groove 2d. A sharp wire separating section 2c is provided at the right end of the protrusion.

[0031] like Figure 3 As shown, the auxiliary wire cutter 3 is in the shape of a sheet, and the rear part is also provided with a connection hole for connecting with the connecting frame by fasteners. The left side of the front part protrudes, and the end of the protruding part has an auxiliary cutting edge 3a.

[0032] like Figure 10 As shown, this sewing thread cutting method includes: S1, such as Figure 4 As shown, the thread guide hole 2b of the main thread cutter 2 is located directly below the sewing machine needle 4. At this time, the main cutting edge 2a is located on the left side of the needle 4, and the thread separating part 2c and the auxiliary thread cutter 3 are both located on the right side of the needle 4. S2, such as Figure 5 As shown, the needle 4 moves downward, driving the thread through the thread guide hole 2b, and the rotary hook 1 drives the free end of the thread to below the main thread cutter 2, so that the thread passes through the thread guide hole 2b. S3, such as Figure 6As shown, after the needle 4 moves upward and disengages from the main thread cutter 2, the main thread cutter 2 rotates clockwise around the rotary hook 1 and moves to the right towards the auxiliary thread cutter 3 until the main cutting edge 2a, the thread guide hole 2b, and the thread separating part 2c on the main thread cutter 2 are all located to the right of the needle 4, offset from the position directly below the needle 4; the thread pressing part of the pressing plate 5 and the main thread cutter 2 cooperate to clamp the top thread. At this time, the main cutting edge 2a is located between the auxiliary cutting edge 3a and the needle 4. S4, such as Figure 7 As shown, after the needle 4 sews the set number of stitches, both the main thread cutter 2 and the auxiliary thread cutter 3 rotate counterclockwise to the left around the rotary hook 1, and the rotation speed of the auxiliary thread cutter 3 is faster than that of the main thread cutter 2. The main cutting edge 2a of the main thread cutter 2 and the auxiliary cutting edge 3a of the auxiliary thread cutter 3 cut the thread end below the needle 4. At the same time, the suction nozzle 6 draws the thread end into the suction nozzle 6 to facilitate the cutting of the thread. In this embodiment, the number of stitches sewed by the needle 4 is set according to the actual sewing needs, for example, three stitches. S5, such as Figure 8 As shown, the main thread cutter 2 continues to rotate counterclockwise around the rotary hook 1 to the left side of the needle 4, and the auxiliary thread cutter 3 rotates clockwise back to the right side of the needle 4. At this time, the thread separating part 2c is located at the rightmost side of the main thread cutter 2. S6, such as Figure 9 As shown, after sewing is completed, the main thread cutter 2 rotates clockwise to the right and the thread separating part 2c separates the threads. The auxiliary thread cutter 3 rotates counterclockwise to the left and the main blade 2a and auxiliary blade 3a cut the bottom thread and top thread attached to the sewing material below the needle 4. S7. The main wire cutter 2 and the auxiliary wire cutter 3 rotate to the initial position in step S1.

[0033] This sewing thread cutting method can first cut off the top thread during the initial sewing stage, and then cut off the bottom and top threads remaining in the fabric after the sewing is completely finished. The entire thread cutting action can be automatically completed by the drive unit driving the main thread cutter 2 and the auxiliary thread cutter 3. The thread cutting effect is stable and can effectively avoid the influence of thread residue on the sewing.

[0034] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A sewing thread cutting method, comprising a thread cutting mechanism, the thread cutting mechanism including a main thread cutter (2) and an auxiliary thread cutter (3) both located on the upper part of a rotary hook (1) in a sewing machine and capable of circular motion around the rotary hook (1), the main thread cutter (2) having a main cutting edge (2a), a thread guide hole (2b) and a thread separating part (2c), and the auxiliary thread cutter (3) having an auxiliary cutting edge (3a), characterized in that, Sewing thread cutting methods include: S1. The thread guide hole (2b) of the main thread cutter (2) is located directly below the sewing machine needle (4). At this time, the main cutting edge (2a) is located on the left side of the needle (4), and the thread separating part (2c) and the auxiliary thread cutter (3) are both located on the right side of the needle (4). S2. The needle (4) moves downward and drives the thread through the lead hole (2b). The rotary hook (1) then drives the free end of the thread to the bottom of the main thread cutter (2), so that the thread passes through the lead hole (2b). S3. After the needle (4) moves upward and disengages from the main thread cutter (2), the main thread cutter (2) rotates clockwise around the rotary hook (1) and moves to the right towards the auxiliary thread cutter (3) until the main cutting edge (2a), the thread guide hole (2b), and the thread separating part (2c) on the main thread cutter (2) are all located on the right side of the needle (4) and offset from the position directly below the needle (4); S4. After the needle (4) sews several stitches, the main thread cutter (2) and the auxiliary thread cutter (3) both rotate counterclockwise to the left around the shuttle (1). The main cutting edge (2a) of the main thread cutter (2) and the auxiliary cutting edge (3a) of the auxiliary thread cutter (3) cut the thread end below the needle (4). S5. The main thread cutter (2) continues to rotate counterclockwise around the rotary hook (1) to the left side of the needle (4), and the auxiliary thread cutter (3) rotates clockwise back to the right side of the needle (4). At this time, the thread separating part (2c) is located on the far right of the main thread cutter (2). S6. After sewing is completed, the main thread cutter (2) rotates clockwise to the right and the thread separating part (2c) separates the thread. The auxiliary thread cutter (3) rotates counterclockwise to the left and the main blade (2a) and auxiliary blade (3a) cut the bottom and top threads attached to the sewing material below the needle (4). S7. The main wire cutter (2) and the auxiliary wire cutter (3) are rotated to their initial positions.

2. The sewing thread cutting method according to claim 1, characterized in that, The wire cutting mechanism also includes a wire pressing plate (5). In step S3, after the main wire cutting blade (2) rotates clockwise around the rotary hook (1) and moves to the right and closes to the auxiliary wire cutting blade (3), the wire pressing plate (5) and the main wire cutting blade (2) clamp the surface wire.

3. The sewing thread cutting method according to claim 2, characterized in that, In step S3, when the pressure plate (5) and the main cutting knife (2) clamp the face thread, the main cutting edge (2a) is located between the auxiliary cutting edge (3a) and the needle (4).

4. A sewing thread-cutting method according to claim 1, 2, or 3, characterized in that, In step S4, both the main wire cutter (2) and the auxiliary wire cutter (3) rotate counterclockwise to the left around the rotary hook (1), and the rotation speed of the auxiliary wire cutter (3) is faster than that of the main wire cutter (2).

5. A sewing thread-cutting method according to claim 1, 2, or 3, characterized in that, The thread cutting mechanism also includes a suction nozzle (6). In step S4, when the main thread cutting knife (2) and the auxiliary thread cutting knife (3) both rotate counterclockwise to the left around the rotary hook (1), the suction nozzle (6) sucks the thread end of the face thread into the suction nozzle (6).

6. A sewing thread cutting method according to claim 1, 2, or 3, characterized in that, In step S7, the main thread cutter (2) and the auxiliary thread cutter (3) are rotated to their initial positions. The thread guide hole (2b) of the main thread cutter (2) is located directly below the sewing machine needle (4), the main cutting edge (2a) is located on the left side of the needle (4), and the thread separating part (2c) and the auxiliary thread cutter (3) are both located on the right side of the needle (4).

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