A thread-cutting structure for a sewing machine

Abstract

This utility model discloses a thread-cutting structure for a sewing machine, including an upper moving blade, a lower moving blade, a first drive mechanism, and a second drive mechanism. The first drive mechanism is connected to the upper moving blade to drive its rotation, and the second drive mechanism is connected to the lower moving blade to drive its rotation. The lower moving blade has a hooking part for hooking the sewing thread. The first and second drive mechanisms work together to enable the upper and lower moving blades to perform thread clamping and cutting operations. The purpose of this utility model is to overcome the shortcomings of the prior art and provide a thread-cutting structure for a sewing machine. This structure aims to achieve reliable clamping and precise thread cutting through independent control and coordinated action of dual drives, thereby effectively preventing stray threads, controlling thread length, and improving equipment reliability and ease of maintenance.

Description

Technical Field

[0001] This utility model relates to the field of sewing equipment technology, specifically to a thread-cutting structure for a sewing machine. Background Technology

[0002] Currently, most sewing machines on the market use a thread-cutting mechanism that uses a drive source in conjunction with a linkage, cam, and other mechanical mechanisms to drive a moving blade and a fixed blade to work together to cut the thread, or to drive two moving blades to complete a simple opening and closing action to cut the thread.

[0003] However, this traditional thread-cutting method has many inherent drawbacks. First, due to the single driving source and complex mechanical linkage, the trajectory and timing of the thread-cutting action are fixed and singular, making it impossible to achieve complex coordinated actions. This results in the thread end left on the needle after cutting being relatively short. When sewing resumes, the excessively short thread end is very likely to slip out of the needle eye, causing "flying thread," which seriously affects the smooth progress of sewing and the stability of sewing quality. Second, if no flying thread occurs, a longer thread end may remain on the front of the product, requiring subsequent manual trimming, which not only increases production steps but also significantly increases labor costs. Even worse, if the thread end is carried to the back of the product during subsequent sewing, it is very easy to tangle into large, messy loops, commonly known in the industry as "bird's nest-like threads," which seriously damages the product's aesthetics and even affects its functionality.

[0004] Therefore, there is an urgent need in this field for a new type of wire-cutting structure that can fundamentally solve the above problems, ensure that the length of the wire end after cutting is moderate and stable, avoid flying wire, and eliminate the quality hazards of excessively long wire ends on the front of the product and bird's nest-like tangles on the back. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a thread-cutting structure for sewing machines. This structure aims to achieve reliable clamping and precise thread cutting through independent dual-drive control and coordinated action, thereby effectively preventing stray threads, controlling thread length, and improving equipment reliability and ease of maintenance.

[0006] To achieve the above objectives, this utility model provides the following technical solution: A thread-cutting structure for a sewing machine includes an upper moving blade, a lower moving blade, a first driving mechanism, and a second driving mechanism. The first driving mechanism is connected to the upper moving blade to drive it to rotate, and the second driving mechanism is connected to the lower moving blade to drive it to rotate. The lower moving blade is provided with a hooking part for hooking the sewing thread. The first driving mechanism and the second driving mechanism work together to make the upper moving blade and the lower moving blade perform thread clamping and thread-cutting operations.

[0007] Furthermore, the upper moving cutter includes an upper moving cutter disc and an upper cutter body detachably connected to the upper moving cutter disc, the upper moving cutter disc being rotatably connected to the spindle; the lower moving cutter includes a lower moving cutter disc and a lower cutter body detachably connected to the lower moving cutter disc, the lower moving cutter disc being rotatably connected to the spindle, and the lower cutter body being provided with a hook section.

[0008] Furthermore, the first drive mechanism includes a first transmission component and a first motor, and the second drive mechanism includes a second transmission component and a second motor.

[0009] Furthermore, the first transmission assembly includes a first bevel gear, a first connecting shaft, and a first connecting rod assembly. The first bevel gear is sleeved and connected to the outside of the first connecting shaft and connected to the output shaft of the first motor. One end of the first connecting shaft is rotatably connected to the machine tool, and the other end is connected to the first connecting rod assembly. The first connecting rod assembly is connected to the upper moving tool disc.

[0010] Furthermore, the second transmission assembly includes a second bevel gear, a second connecting shaft, and a second linkage assembly. The second bevel gear is sleeved and connected to the outside of the second connecting shaft and connected to the output shaft of the second motor. One end of the second connecting shaft is rotatably connected to the machine tool, and the other end is connected to the second linkage assembly. The second linkage assembly is connected to the lower moving cutter head.

[0011] Furthermore, both the first motor and the second motor are stepper motors or servo motors.

[0012] Furthermore, the lower moving cutter head is rotatably connected to the main shaft and has an initial stationary position controlled by the second drive mechanism; in this initial stationary position, the hook portion on the lower cutter body is located directly below the needle.

[0013] Furthermore, the spatial positions of the upper and lower moving blades in the reset state are offset from the spatial position of the needle in the sewing state.

[0014] Furthermore, it also includes a control unit, which is electrically connected to the first drive mechanism and the second drive mechanism respectively, and is used to control the rotation angle and movement sequence of the upper and lower moving blades.

[0015] Compared with existing technologies, the technical solution of this patent achieves the following beneficial effects: By independently and precisely controlling the upper and lower moving blades through a dual-drive mechanism, an optimized process sequence of clamping, fixing, sewing, and cutting is achieved, ensuring that the thread end is firmly held and effectively preventing stray threads. Furthermore, by setting the precise initial position of the lower moving blade, the shortest and most stable thread length after cutting is guaranteed, completely avoiding long thread ends on the front and "bird's nest" problems on the back. Using a stepper motor or servo motor as the drive source, combined with bevel gear transmission, precise control of the rotating angle and timing of the moving blades is achieved, resulting in accurate and reliable operation with low noise. Attached Figure Description

[0016] Figure 1 This is a three-dimensional structural diagram of the wire-cutting structure of this utility model; Figure 2 for Figure 1 A magnified schematic diagram of the AA section in the diagram; Figure 3 This is a three-dimensional structural diagram of the wire-cutting structure of this utility model; Figure 4 for Figure 3 A magnified schematic diagram of the BB section in the image; Figure 5 A three-dimensional structural diagram of the thread-cutting structure of this utility model assembled in a sewing machine tool; Figure 6 This is a top view schematic diagram of the thread-cutting structure of this utility model assembled in a sewing machine tool; Figure 7 This is a side view of the thread-cutting structure of this utility model assembled in a sewing machine.

[0017] In the diagram: 1. Upper moving tool; 11. Upper moving tool disc; 12. Upper tool body; 2. Lower moving tool; 21. Lower moving tool disc; 22. Lower tool body; 220. Hooking section; 3. First drive mechanism; 31. First transmission assembly; 32. First motor; 311. First bevel gear; 312. First connecting shaft; 313. First link assembly; 4. Second drive mechanism; 41. Second transmission assembly; 42. Second motor; 421. Second bevel gear; 412. Second connecting shaft; 413. Second link assembly; 5. Spindle; 6. Machine tool. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0019] See Figure 1-7As shown, this embodiment provides a technical solution: a thread-cutting structure for a sewing machine, including an upper moving blade 1, a lower moving blade 2, a first drive mechanism 3, a second drive mechanism 4, and a control unit. The first drive mechanism 3 is connected to the upper moving blade 1 to drive its rotation, and the second drive mechanism 4 is connected to the lower moving blade 2 to drive its rotation. The lower moving blade 2 has a hook portion 220 for hooking the thread, which can be a hole or a hook-shaped structure, used to hook the thread during operation. The first drive mechanism 3 and the second drive mechanism 4 work together to enable the upper moving blade 1 and the lower moving blade 2 to perform thread clamping and cutting operations. By setting the first drive mechanism 3 and the second drive mechanism 4 to drive the upper moving blade 1 and the lower moving blade 2 independently, a solid foundation is laid structurally for achieving flexible and precise coordinated operation between the two. This allows the upper and lower moving blades to perform asymmetrical or sequential compound movements, thus firmly clamping the thread end before sewing. This fundamentally prevents the problem of thread ends detaching from the needle at the start of sewing, greatly improving sewing stability and product quality.

[0020] The upper moving cutter 1 includes an upper moving cutter disc 11 and an upper cutter body 12 detachably connected to the upper moving cutter disc 11. The upper moving cutter disc 11 is rotatably connected to the main shaft 5. The lower moving cutter 2 includes a lower moving cutter disc 21 and a lower cutter body 22 detachably connected to the lower moving cutter disc 21. The lower moving cutter disc 21 is rotatably connected to the main shaft 5, and the lower cutter body 22 is provided with a hooking part 220. This modular design, with detachable connections between the upper / lower moving cutter discs and the upper / lower cutter bodies, adapts to different sewing environments. This allows the cutter body, as a consumable part, to be replaced independently and conveniently, significantly reducing maintenance costs and downtime, while ensuring the long-term reliability of the moving cutter disc transmission components.

[0021] The first drive mechanism 3 includes a first transmission assembly 31 and a first motor 32, and the second drive mechanism 4 includes a second transmission assembly 41 and a second motor 42. Each drive mechanism is equipped with an independent motor and transmission assembly, forming two parallel and complete drive chains. This structural layout is reasonable, the power transmission path is clear, and it ensures the independence of each drive and the overall reliability of the system.

[0022] The first transmission assembly 31 includes a first bevel gear 311, a first connecting shaft 312, and a first connecting rod assembly 313. The first bevel gear 311 is sleeved and connected to the outside of the first connecting shaft 312 and connected to the output shaft of the first motor 32. One end of the first connecting shaft 312 is rotatably connected to the machine tool 6, and the other end is connected to the first connecting rod assembly 313. The first connecting rod assembly 313 is connected to the upper moving tool head 11. The second transmission assembly 41 includes a second bevel gear 421, a second connecting shaft 412, and a second connecting rod assembly 413. The second bevel gear 421 is sleeved and connected to the outside of the second connecting shaft 412 and connected to the output shaft of the second motor 42. One end of the second connecting shaft 412 is rotatably connected to the machine tool 6, and the other end is connected to the second connecting rod assembly 413. The second connecting rod assembly 413 is connected to the lower moving tool head 21. The transmission assembly composed of bevel gears, connecting shafts, and connecting rod assemblies, especially the bevel gear structure, can efficiently change the direction of power transmission and is very suitable for realizing the rotary motion required for the moving tool in a limited space. This structure features smooth transmission and high rigidity, ensuring accurate positioning of the moving tool and timely action response.

[0023] Both the first motor 32 and the second motor 42 are stepper motors or servo motors. Using stepper motors or servo motors as actuators inherently offers advantages such as high control precision, smooth low-speed operation, and low noise. This structural choice directly improves the performance of the entire wire-cutting system, enabling precise control of the moving blade's rotation angle, quieter operation, and a longer lifespan.

[0024] The lower cutting disc 21 is rotatably connected to the main shaft 5 and has an initial position controlled by the second drive mechanism 4; in this initial position, the hook portion 220 on the lower cutting body 22 is located directly below the needle. This inherent mechanical positioning ensures that the thread is pulled to its shortest and most consistent state before each cut, thus guaranteeing a short and consistent thread length after cutting. This structurally avoids quality problems such as the need for manual trimming due to excessively long thread ends or the thread ends tangling on the back, forming a bird's nest-like ball, improving product aesthetics and reducing labor costs.

[0025] The spatial positions of the upper moving blade 1 and the lower moving blade 2 in their reset state are offset from the spatial position of the sewing needle in its sewing state. Through mechanical design, this offset ensures that the spatial positions of the upper and lower moving blades in their reset state are mutually offset from the working space of the needle. This inherent, static positional avoidance relationship fundamentally eliminates the possibility of collision between the moving blades and the needle, greatly improving the safety and reliability of the equipment operation.

[0026] The control unit is electrically connected to the first drive mechanism 3 and the second drive mechanism 4, respectively, and is used to control the rotation angle and movement timing of the upper moving blade 1 and the lower moving blade 2. The control unit acts as the system's brain, electrically connected to both drive mechanisms. This system construction achieves centralized and precise programmable control of the rotation angle and movement timing of the two moving blades, ensuring the automation, reliability, and consistency of the entire process of hooking, clamping, sewing, tightening, cutting, and avoiding obstacles. This is key to leveraging all the advantages of the aforementioned mechanical structure. It should be noted that the control unit, such as a programmable logic controller or a dedicated microprocessor, is electrically connected to the first motor 32 and the second motor 42 via wiring. The control unit contains a pre-stored control program used to send precise command signals to the two motors, controlling their start, stop, rotation direction, angle, and movement timing, thereby enabling the upper moving blade 1 and the lower moving blade 2 to collaboratively complete the workflow.

[0027] The working principle of the thread-cutting structure of this sewing machine is as follows: Before sewing begins, the second drive mechanism 4 controls the lower moving blade 2 to its initial position. In this position, the hook part 220 is precisely located directly below the needle, preparing for subsequent thread hooking. The needle carries the thread downwards, completing the first stitch. Subsequently, the second drive mechanism 4 starts, driving the lower blade body 22 to rotate around the main shaft 5 via the second transmission assembly 41. During the rightward rotation, the hook part 220 on the lower blade body 22 hooks the thread on the needle, cooperating with the stationary or cooperating upper moving blade 1 to clamp the thread end. With the thread end clamped, the sewing machine performs subsequent sewing (such as sewing two to three stitches). The clamped thread end is firmly fixed in the fabric, eliminating the problem of stray thread. When sewing ends and thread cutting is required, the second drive mechanism 4 drives the lower moving blade 2 to rotate leftward, causing its hook part 220 to precisely return to its initial position directly below the needle. This action tightens the thread to its shortest length. Immediately afterwards, the first drive mechanism 3 drives the upper moving blade 1 to rotate counter-clockwise, and the cutting edge of the upper blade 12 cuts the thread. Because the thread has been pulled to its shortest length before cutting, the thread end left on the product after cutting is extremely short, effectively solving the quality problems of excessively long thread ends and the "bird's nest" effect on the back. After cutting the thread, both drive mechanisms drive the upper and lower moving blades to rotate and reset, clearing the working space of the needle. This completes one thread-cutting cycle. When sewing is needed again, the entire mechanism will repeat the above process.

Claims

1. A thread trimming structure of a sewing machine comprising an upper knife (1), a lower knife (2), a first driving mechanism (3) and a second driving mechanism (4), characterized in that: The first drive mechanism (3) is connected to the upper moving blade (1) to drive the upper moving blade (1) to rotate. The second drive mechanism (4) is connected to the lower moving blade (2) to drive the lower moving blade (2) to rotate. The lower moving blade (2) is provided with a hook part (220) for hooking the sewing thread. The first drive mechanism (3) and the second drive mechanism (4) work together to make the upper moving blade (1) and the lower moving blade (2) perform thread clamping and thread cutting operations.

2. The thread-cutting structure of the sewing machine according to claim 1, characterized in that: The upper moving cutter (1) includes an upper moving cutter disc (11) and an upper cutter body (12) detachably connected to the upper moving cutter disc (11). The upper moving cutter disc (11) is rotatably connected to the main shaft (5). The lower moving cutter (2) includes a lower moving cutter disc (21) and a lower cutter body (22) detachably connected to the lower moving cutter disc (21). The lower moving cutter disc (21) is rotatably connected to the main shaft (5), and the lower cutter body (22) is provided with the hook part (220).

3. The thread-cutting structure of the sewing machine according to claim 2, characterized in that: The first drive mechanism (3) includes a first transmission component (31) and a first motor (32), and the second drive mechanism (4) includes a second transmission component (41) and a second motor (42).

4. The thread-cutting structure of the sewing machine according to claim 3, characterized in that: The first transmission assembly (31) includes a first bevel gear (311), a first connecting shaft (312), and a first connecting rod assembly (313). The first bevel gear (311) is sleeved and connected to the outside of the first connecting shaft (312) and connected to the output shaft of the first motor (32). One end of the first connecting shaft (312) is rotatably connected to the machine tool (6), and the other end is connected to the first connecting rod assembly (313). The first connecting rod assembly (313) is connected to the upper moving tool disc (11).

5. The thread-cutting structure of the sewing machine according to claim 3, characterized in that: The second transmission assembly (41) includes a second bevel gear (421), a second connecting shaft (412), and a second linkage assembly (413). The second bevel gear (421) is sleeved and connected to the outside of the second connecting shaft (412) and connected to the output shaft of the second motor (42). One end of the second connecting shaft (412) is rotatably connected to the machine tool (6), and the other end is connected to the second linkage assembly (413). The second linkage assembly (413) is connected to the lower moving cutter head (21).

6. The thread-cutting structure of the sewing machine according to claim 3, characterized in that: Both the first motor (32) and the second motor (42) are stepper motors or servo motors.

7. The thread-cutting structure of the sewing machine according to claim 2, characterized in that: The lower moving cutter head (21) is rotatably connected to the main shaft (5) and has an initial stationary position controlled by the second drive mechanism (4); in this initial stationary position, the hook part (220) on the lower cutter body (22) is located directly below the needle.

8. The thread-cutting structure of the sewing machine according to claim 1, characterized in that: The spatial positions of the upper moving blade (1) and the lower moving blade (2) in the reset state are offset from the spatial position of the needle in the sewing state.

9. The thread-cutting structure of the sewing machine according to claim 1, characterized in that: It also includes a control unit, which is electrically connected to the first drive mechanism (3) and the second drive mechanism (4) respectively, and is used to control the rotation angle and movement sequence of the upper moving blade (1) and the lower moving blade (2).

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