A thread trimming mechanism of a keyhole cutting machine

Abstract

The utility model provides a kind of thread cutting mechanism of lock eye machine, belong to sewing machine technical field.It solves the problem that thread hair gathering caused by thread cutting in existing thread cutting mechanism cannot be discharged, leading to normal thread cutting cannot be carried out.The thread cutting mechanism of the lock eye machine, including fixed knife, moving knife and needle plate with pinhole, moving knife has thread hook, moving knife can move forward and backward to make thread hook cooperate with fixed knife to cut thread, the lower surface of needle plate is provided with movable slot, pinhole is arranged on the bottom surface of movable slot, thread hook is located in movable slot, the upper surface of needle plate is provided with fixed slot located in front of pinhole, the rear side and bottom surface of fixed slot are communicated with the wall surface of movable slot and form communicating port, fixed knife is fixedly connected in fixed slot and covers part of communicating port, the rear side of fixed knife and the upper mouth of communicating port are spaced apart, and the front side of fixed knife and the front mouth of communicating port are spaced apart.The thread cutting mechanism makes moving knife not be jammed or even be stuck due to thread hair gathering, so that thread cutting can be carried out normally.

Description

Technical Field

[0001] This utility model belongs to the field of sewing machine technology and relates to a thread-cutting mechanism for a buttonhole machine. Background Technology

[0002] A sewing machine is a machine that sews fabric together with thread. It includes a needle bar mechanism, thread take-up mechanism, feed mechanism, thread hooking mechanism, pressing mechanism, thread winding device, and lubrication device. Sewing machines can be classified according to their structure or sewing process into flatbed sewing machines, chain stitch machines, overlock sewing machines, buttonhole machines, and sealing machines. Buttonhole machines are used to process buttonholes in various garments. The operation of a buttonhole machine is similar to that of a regular sewing machine; the thread moves up and down with the needle, creating stitches on the fabric.

[0003] To achieve automatic thread cutting in buttonhole machines, a thread-cutting mechanism is typically installed below the needle plate. For example, an automatic thread-cutting device for a sewing machine disclosed in Chinese patent literature (publication number CN208917470U) includes a fixed blade and a moving blade. A guide rail is fixed below the needle plate, the fixed blade is fixed between the needle plate and the guide rail, and the moving blade is installed in the guide rail and can move linearly along the guide rail. The moving blade has a thread-hooking groove; when cutting the thread, the hooking groove hooks the thread and moves it towards the fixed blade. The thread is cut through the cooperation of the fixed blade and the moving blade. However, in this thread-cutting device, when the moving blade moves towards the fixed blade to cut the thread, the lint produced during cutting cannot be discharged and tends to accumulate between the guide rail and the fixed blade, causing the moving blade to jam or even become stuck, thus preventing normal thread cutting. Utility Model Content

[0004] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a thread-cutting mechanism for a buttonhole machine, which solves the technical problem that the accumulation of lint generated during thread cutting in the existing thread-cutting mechanism cannot be discharged, thus preventing normal thread cutting.

[0005] The objective of this utility model can be achieved through the following technical solutions: A thread-cutting mechanism for a buttonhole machine includes a fixed blade, a movable blade, and a needle plate with a needle hole. The movable blade has a thread hook, and the movable blade can move back and forth to allow the thread hook to cooperate with the fixed blade to cut the thread. The lower surface of the needle plate has a movable groove, the needle hole is located on the bottom surface of the movable groove, and the thread hook is located in the movable groove. The upper surface of the needle plate has a fixed groove located in front of the needle hole. The rear side and bottom surface of the fixed groove are connected to the wall of the movable groove to form a connecting opening. The fixed blade is fixedly connected in the fixed groove and covers part of the connecting opening. The rear side of the fixed blade and the upper edge of the connecting opening, as well as the front side of the fixed blade and the front edge of the connecting opening, are spaced apart.

[0006] The rear side of the fixed blade is the cutting edge, and the front side is the back of the blade. During thread cutting, the moving blade hooks the thread at the needle hole and moves it towards the fixed blade (forward). The hook then works with the fixed blade to cut the thread. Afterward, the moving blade retracts away from the fixed blade. At this point, the thread fibers produced during cutting adhere to the lower surface and rear side of the fixed blade, as well as to the hook. The moving blade moves back and forth multiple times to cut the thread. The thread fibers on the moving blade can fall downward through the slot of the movable groove during its movement. The thread fibers adhering to the lower surface of the fixed blade continuously gather and are pushed forward by the hook, allowing them to be discharged through the gap between the front side of the moving blade and the front edge of the connecting port. The thread fibers adhering to the rear side of the fixed blade continuously gather and are squeezed upward by the hook, allowing them to be discharged through the gap between the rear side of the moving blade and the upper edge of the connecting port. This achieves automatic fiber removal, preventing the moving blade from jamming or even stopping due to thread accumulation, and ensuring normal thread cutting.

[0007] In the thread-cutting mechanism of the aforementioned buttonhole machine, a notch is provided on the front side of the fixed blade, making the fixed blade "L" or "U" shaped. This not only allows for fixing and positioning of the fixed blade at its end, ensuring its stability, but also facilitates automatic lint removal, which helps ensure normal thread cutting.

[0008] In the thread-cutting mechanism of the aforementioned buttonhole machine, the fixed blade is in the shape of an "I" and its width is one-third to three-quarters of the width of the fixing groove. This design makes the fixed blade easy to manufacture and also enables automatic lint removal, which helps ensure normal thread cutting.

[0009] In the thread-cutting mechanism of the aforementioned buttonhole machine, the moving blade is strip-shaped, and the thread hook is located on the side of the moving blade near the needle hole. A drive handle is located on the other side of the moving blade. Guide grooves are respectively provided at both ends of the lower surface of the needle plate, and both ends of the moving blade are embedded into the corresponding guide grooves. The drive handle is used to connect to a drive source to drive the moving blade to move. The guide grooves guide the moving blade, ensuring stable movement and facilitating smooth thread cutting.

[0010] In the thread-cutting mechanism of the aforementioned buttonhole machine, a clearance groove is also provided on the lower surface of the needle plate between the two guide grooves, and the drive handle is located in the clearance groove. The clearance groove serves to avoid the drive handle, and at the same time, the side walls at both ends of the clearance groove limit the drive handle, preventing the moving blade from moving excessively and causing the hook to collide with the side wall of the movable groove, thus facilitating smooth thread cutting.

[0011] In the thread-cutting mechanism of the buttonhole machine described above, a pressure plate located below the moving blade is fixedly connected to the lower surface of the needle plate. The pressure plate is located behind the needle hole, and the side of the pressure plate closest to the needle hole is inclined downward.

[0012] After the thread is cut, the top thread falls off the hook and hangs behind it due to gravity. When the moving blade moves backward, the top thread is pushed backward by the hook and enters the pressure plate. The thread end is held in place by the pressure plate and the moving blade, preventing it from coming undone when the sewing begins. The pressure plate not only limits the moving blade to prevent it from falling off the needle plate, but also presses down the thread to prevent it from coming undone when the sewing begins.

[0013] In the thread-cutting mechanism of the buttonhole machine described above, a pressure plate located below the moving knife is fixedly connected to the lower surface of the needle plate. The pressure plate is positioned corresponding to the fixed knife, and the side of the pressure plate near the needle hole is bent downwards and smoothly transitioned.

[0014] When cutting the thread, the thread hook catches the thread and moves it between the fixed blade and the pressure plate. The pressure plate holds the thread between the moving blade and the pressure plate, and the fixed blade, in conjunction with the thread hook, cuts the thread. The pressure plate not only limits the moving blade, preventing it from falling off the needle plate, but also presses the thread down, preventing it from coming undone during cutting and ensuring the thread is cut smoothly. The side of the pressure plate closest to the needle eye bends downwards, allowing the thread to smoothly enter above the pressure plate and preventing it from getting stuck.

[0015] In the above-mentioned buttonhole machine's wire cutting mechanism, the buttonhole machine's wire cutting mechanism also includes a swinging component. A lever is fixedly connected to the swinging arm of the swinging component. The end of the lever has a slot, and the drive handle is inserted into the slot.

[0016] When the swinging component swings, it drives the moving blade to slide through the lever and drive handle. The lever and drive handle are connected by a slot, which can avoid motion interference caused by converting the swinging motion of the lever into the linear motion of the moving blade, so that the moving blade can move smoothly to cut the wire.

[0017] Compared with the prior art, the present invention has the following advantages: The lower surface of the needle plate has a movable groove, and the upper surface has a fixed groove. A connecting opening exists between the fixed and movable grooves. The fixed blade is fixedly connected in the fixed groove and partially covers the connecting opening. The rear side of the fixed blade is spaced apart from the upper edge of the connecting opening, and the front side of the fixed blade is spaced apart from the front edge of the connecting opening. This allows the lint generated during thread cutting to be automatically discharged, preventing the moving blade from getting stuck or jammed due to lint accumulation, thus ensuring the thread cutting process proceeds normally. The pressure plate not only limits the moving blade to prevent it from falling downwards but also presses the thread down during sewing to prevent it from unraveling. The pressure plate not only limits the moving blade to prevent it from falling downwards but also presses the thread down during cutting, facilitating smooth thread cutting. Attached Figure Description

[0018] Figure 1 This is a perspective view of Embodiment 1 of the buttonhole machine's wire-cutting mechanism.

[0019] Figure 2 This is a partial top view of Embodiment 1 of the buttonhole machine's wire-cutting mechanism.

[0020] Figure 3 yes Figure 2 A cross-sectional view along the AA direction.

[0021] Figure 4 This is a partial perspective view of Embodiment 1 of the buttonhole machine's thread-cutting mechanism, viewed from below.

[0022] Figure 5 This is a three-dimensional view of the needle plate in Embodiment 1 of the thread-cutting mechanism of this buttonhole machine.

[0023] Figure 6 This is a schematic diagram of the wire cutting process in Embodiment 1 of the buttonhole machine's wire cutting mechanism.

[0024] In the diagram, 1. Fixed blade; 1a. Notch; 2. Moving blade; 2a. Thread hook; 2b. Drive handle; 3. Needle plate; 3a. Needle hole; 3b. Movable groove; 3c. Fixed groove; 3d. Guide groove; 3e. Clearance groove; 3f. Connecting port; 4. Swinging component; 4a. Swinging arm; 5. Lever; 5a. Slot; 6. Hinge shaft; 7. Thread pressing plate; 8. Blade pressing plate; 9. Top thread. Detailed Implementation

[0025] 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.

[0026] Example 1

[0027] like Figure 1 and Figure 2 As shown, a thread-cutting mechanism for a buttonhole machine includes a fixed blade 1, a movable blade 2, a swinging component 4, and a needle plate 3 with a needle hole 3a. The needle plate 3 is fixedly connected to the base of the buttonhole machine. The swinging component 4 is hinged to the base of the buttonhole machine via a hinge shaft 6. The swinging component 4 can be driven by a motor, a cylinder, or an electromagnet. A lever 5 is fixedly connected to the swing arm 4a of the swinging component 4. The end of the lever 5 has a slot 5a, into which the drive handle 2b of the movable blade 2 is inserted.

[0028] like Figure 3 and Figure 4 As shown, the moving blade 2 has a hook 2a, which can move back and forth to engage with the fixed blade 1 to cut the thread. Figure 5As shown, a movable groove 3b communicating with a needle hole 3a is formed on the lower surface of the needle plate 3. The needle hole 3a is located on the bottom surface of the movable groove 3b, and the hook 2a is located in the movable groove 3b. A fixed groove 3c is formed on the upper surface of the needle plate 3, located in front of the needle hole 3a and communicating with the movable groove 3b. The rear side and bottom surface of the fixed groove 3c are connected to the wall of the movable groove 3b to form a connecting opening 3f. A notch 1a is provided at the back of the fixed knife 1 to make the fixed knife 1 "L" shaped. The fixed knife 1 is fixedly connected in the fixed groove 3c, and the blade of the fixed knife 1 faces the needle hole 3a. The back of the fixed knife 1 is the front side of the fixed knife 1, and the blade of the fixed knife 1 is the rear side of the fixed knife 1. The fixed knife 1 covers part of the connecting opening 3f, and there are intervals between the rear side of the fixed knife 1 and the upper edge of the connecting opening 3f, and between the front side of the fixed knife 1 and the front edge of the connecting opening 3f. The moving blade 2 is strip-shaped. A hook 2a is positioned on the side of the moving blade 2 closest to the needle hole 3a, and a drive handle 2b is positioned on the other side of the moving blade 2 facing away from the needle hole 3a. Guide grooves 3d are provided at both ends of the lower surface of the needle plate 3, and the two ends of the moving blade 2 are embedded in the guide grooves 3d. A clearance groove 3e is also provided on the lower surface of the needle plate 3 between the two guide grooves 3d, and the drive handle 2b is located in the clearance groove 3e. A pressure plate 7, located below the moving blade 2, is fixedly connected to the lower surface of the needle plate 3. The pressure plate 7 corresponds to the position of the fixed blade 1, and the side of the pressure plate 7 closest to the needle hole 3a is bent downwards. A pressure plate 8, located below the moving blade 2, is fixedly connected to the lower surface of the needle plate 3. The pressure plate 8 and the pressure plate 7 are located on opposite sides of the needle hole 3a, and the side of the pressure plate 8 closest to the needle hole 3a is bent downwards.

[0029] like Figure 6As shown, the direction from the needle hole 3a to the fixed knife 1 is the front. Before sewing, the thread hook 2a of the moving knife 2 is located behind the needle hole 3a, so that the thread hook 2a avoids the needle hole 3a. After sewing is completed, the moving knife 2 moves forward, the thread hook 2a contacts and hooks the sewing thread, the moving knife 2 continues to move forward, the sewing thread is clamped between the moving knife 2 and the pressing plate 7, and the thread hook 2a cooperates with the blade of the fixed knife 1 to cut the thread. A part of the lint generated by the thread cutting falls out from the notch of the movable groove, a part adheres to the rear side surface of the blade of the fixed knife 1, and a part adheres to the lower surface of the fixed knife 1. After the sewing thread is cut, the top thread 9 falls off from the thread hook 2a and drops behind the thread hook 2a due to gravity; then the moving knife 2 moves backward, the top thread 9 is pushed backward by the thread hook 2a and enters the pressing knife plate 8, and the end of the top thread 9 is clamped by the pressing knife plate 8 and the moving knife 2 to prevent the thread from coming off at the start of sewing. The moving knife 2 reciprocates to cut the thread multiple times. The lint adhering to the lower surface of the fixed knife 1 continuously accumulates and is pushed forward by the thread hook 2a of the moving knife 2, and will be discharged from the gap between the front side of the fixed knife 1 and the front edge of the communication port 3f. The lint adhering to the rear side surface of the blade of the fixed knife 1 continuously accumulates and moves upward, and is discharged from the gap between the rear side of the fixed knife 1 and the upper edge of the communication port 3f, and finally discharged from the fixed groove 3c. In this way, automatic lint discharge is achieved, so that the moving knife 2 will not be stuck or even jammed due to lint accumulation, and the thread cutting can be carried out normally.

[0030] Embodiment 2

[0031] The structure of the fixed knife 1 is slightly different from that of Embodiment 1, and other structures are basically the same as those of Embodiment 1. A notch 1a is provided at the back of the knife back of the fixed knife 1 so that the fixed knife 1 is in a "U" shape, and the lint is discharged from the notch 1a.

[0032] Embodiment 3

[0033] 2]The structure of the fixed knife 1 is slightly different from that of Embodiment 1, and other structures are basically the same as those of Embodiment 1. The fixed knife 1 is in a "one" shape, and the width of the fixed knife 1 is one-third to three-fourths of the width of the fixed groove 3c. Preferably, the width of the fixed knife 1 is the same as the width of the fixed knife 1 where the notch 1a is located in Embodiment 1, the width of the fixed groove 3c is the same as that in Embodiment 1, and both ends of the fixed knife 1 are fixedly connected to the needle plate 3 by smaller screws.

[0034] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, but will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A thread-cutting mechanism for a buttonhole machine, comprising a fixed blade (1), a movable blade (2), and a needle plate (3) having a needle hole (3a), wherein the movable blade (2) has a thread hook (2a), and the movable blade (2) is capable of moving back and forth to allow the thread hook (2a) to cooperate with the fixed blade (1) to cut the thread, characterized in that, On the lower surface of the needle plate (3), an activity groove (3b) is provided. The needle hole (3a) is arranged on the bottom surface of the activity groove (3b). The thread hook (2a) is located in the activity groove (3b). On the upper surface of the needle plate (3), a fixed groove (3c) is provided in front of the needle hole (3a). The rear side and the bottom surface of the fixed groove (3c) are both communicated with the wall surface of the activity groove (3b) to form a communication port (3f). The fixed cutter (1) is fixedly connected in the fixed groove (3c) and covers part of the communication port (3f). There is a gap between the rear side part of the fixed cutter (1) and the upper edge of the communication port (3f), and also a gap between the front side part of the fixed cutter (1) and the front edge of the communication port (3f).

2. The thread-cutting mechanism of the buttonhole machine according to claim 1, characterized in that, A notch (1a) is provided on the front side part of the fixed cutter (1) so that the fixed cutter (1) is in an "L" shape or a "凵" shape.

3. The thread-cutting mechanism of the buttonhole machine according to claim 1, characterized in that, The fixed cutter (1) is in a "一" shape, and the width of the fixed cutter (1) is one-third to three-fourths of the width of the fixed groove (3c).

4. The thread-cutting mechanism of the buttonhole machine according to any one of claims 1-3, characterized in that, The moving cutter (2) is in a strip shape. The thread hook (2a) is arranged on one side of the moving cutter (2) close to the needle hole (3a). On the other side of the moving cutter (2), there is a driving handle (2b). On the lower surface of the needle plate (3) at both ends of the needle plate (3), guiding grooves (3d) are respectively provided. The two ends of the moving cutter (2) are respectively inserted into the corresponding guiding grooves (3d).

5. The thread-cutting mechanism of the buttonhole machine according to claim 4, characterized in that, On the lower surface of the needle plate (3) between the two guiding grooves (3d), an avoidance groove (3e) is also provided. The driving handle (2b) is located in the avoidance groove (3e).

6. The thread-cutting mechanism of the buttonhole machine according to claim 4, characterized in that, On the lower surface of the needle plate (3), a pressing cutter plate (8) is fixedly connected below the moving cutter (2). The pressing cutter plate (8) is located behind the needle hole (3a). One side of the pressing cutter plate (8) close to the needle hole (3a) is inclined downward.

7. The thread-cutting mechanism of the buttonhole machine according to claim 6, characterized in that, On the lower surface of the needle plate (3), a wire pressing plate (7) is fixedly connected below the moving cutter (2). The wire pressing plate (7) corresponds to the position of the fixed cutter (1). One side of the wire pressing plate (7) close to the needle hole (3a) is bent downward and has a smooth transition.

8. The thread-cutting mechanism of the buttonhole machine according to claim 4, characterized in that, The thread cutting mechanism of the keyhole sewing machine further includes a swinging member (4). A dial rod (5) is fixedly connected to the swinging arm (4a) of the swinging member (4). A slot (5a) is provided at the end of the dial rod (5). The driving handle (2b) is inserted into the slot (5a).

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