Bird nest prevention mechanism for a sewing machine

Abstract

The utility model belongs to sewing machine technical field. It has solved the problem of bird's nest stitch in the needle lifting position in the clothing sewing in the prior art. Provide a kind of anti-bird's nest mechanism of sewing machine, including the cutting thread movable knife being set in the below of needle plate and can rotate around rotating shuttle, its characterized in that, cutting thread movable knife has the thread catching hole for the needle through on it, the present anti-bird's nest mechanism further includes the thread pressing piece being set in the outside of cutting thread movable knife and can rotate around rotating shuttle, cutting thread movable knife can be attached with thread pressing piece and drive thread pressing piece swing towards the same direction, needle plate is equipped with the thread passing hole being located in the front of cutting thread fixed knife and being connected with needle hole, needle plate is further connected with cutting thread knife, the cutting edge of cutting thread knife is set towards needle hole and is located in the directly above or directly below of thread passing hole;Or needle plate is further integrally formed with cutting thread knife, the cutting edge of cutting thread knife is set towards needle hole and is located in thread passing hole. With the advantage that the bird's nest stitch in the needle lifting position in the existing clothing sewing can be solved.

Description

Technical Field

[0001] This utility model belongs to the field of sewing machine technology and relates to an anti-bird nest mechanism for sewing machines. Background Technology

[0002] The thread-cutting mechanism of most commercially available sewing machines consists of a movable blade and a fixed blade located below the needle plate and above the rotary hook. The fixed blade is fixed to the sewing machine base, while the movable blade is driven by a drive mechanism and rotates around a lower shaft, engaging with the fixed blade on the needle side to cut the thread. To ensure a smooth knot formation for the next stitch, a longer section of the top thread is left on the needle. This section of top thread is interwoven and wrapped around the fabric during the first few stitches, forming a "bird's nest" stitch.

[0003] To eliminate the stitches in bird's nests, Chinese patent literature discloses a cutting device and its cutting method (application number: 202310840244.X), which includes a sewing machine knife, and fixed knives are respectively provided for the sewing machine knife. The sewing machine knife includes a first cutting knife, which includes a thread groove and a first cutting edge. A second cutting knife is provided for the first cutting knife, which includes a needle drop groove and a second cutting edge.

[0004] The aforementioned cutting device has the following shortcomings during use: At the end of sewing, the top thread is cut off by the first cutting blade in conjunction with the fixed blade. When sewing begins again, after the needle rises above the moving blade, the sewing machine's moving blade continues to move forward. The second cutting blade on the moving blade, in conjunction with the fixed blade, cuts the starting thread. However, because the cutting point is far from the needle plate hole, the top thread remains relatively long after being cut. This causes the starting thread to form a bird's nest-like pattern on the garment during the second stitch, affecting the overall quality of the garment. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in existing technologies by proposing an anti-bird's nest mechanism for sewing machines. The technical problem this invention aims to solve is addressing the issue of bird's nest-like stitches at the starting point of existing garment sewing.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] An anti-bird nest mechanism for a sewing machine includes a machine base, a needle plate disposed on the upper surface of the machine base and having needle holes, and a rotary hook and a thread-cutting fixed blade respectively disposed below the needle plate. The anti-bird nest mechanism includes a thread-cutting movable blade disposed below the needle plate and capable of rotating up and down around the rotary hook. The thread-cutting movable blade has a thread-grabbing hole for the needle to pass through. The anti-bird nest mechanism also includes a thread-pressing plate disposed outside the thread-cutting movable blade and capable of rotating up and down around the rotary hook. The thread-cutting movable blade can adhere to the thread-pressing plate and drive the thread-pressing plate to swing in the same direction. The needle plate has a thread-passing hole located in front of the thread-cutting fixed blade and communicating with the needle holes. A thread-cutting blade is also connected to the needle plate, with the blade facing the needle holes and located directly above or below the thread-passing hole; or the needle plate may also have a thread-cutting blade integrally formed therein, with the blade facing the needle holes and located within the thread-passing hole.

[0008] The anti-bird's nest mechanism of this sewing machine has a thread-cutting position that is close to the needle hole of the needle plate, which ensures that the thread end remaining on the sewing fabric is short enough, thus solving the problem of bird's nest-like stitches at the starting point in existing garment sewing.

[0009] Specifically, at the start of sewing, the larger end of the thread-grabbing hole of the moving thread cutter (i.e., the end furthest from the fixed thread cutter) is directly below the needle. The needle pulls the top thread into the thread-grabbing hole, and as the needle begins to rise, the top thread forms a small loop under the fabric. The hook tip passes through the small loop, bringing the top thread intact to below the moving thread cutter; as the needle moves upward away from the thread-grabbing hole, the moving thread cutter swings towards the pressure plate (i.e., downward). During the movement of the moving thread cutter, the top thread is held in place by the leading edge of the pressure plate, thus sliding within the thread-grabbing hole until it reaches the smaller end of the thread-grabbing hole (i.e., the end near the fixed thread cutter), and is finally pressed by the pressure plate onto the arcuate surface of the moving thread cutter near the smaller end (the moving thread cutter and the pressure plate are in contact).

[0010] The thread-cutting blade remains stationary and continues sewing several stitches. Afterward, the thread-cutting blade drives the pressure plate to continue swinging synchronously towards the pressure plate, thus maintaining the close contact and clamping of the thread between the thread-cutting blade and the pressure plate. The thread-cutting blade and the pressure plate, holding the thread, move downwards away from the needle, and the fabric is pushed forward by the feed device during sewing. Together, they move the thread end towards the blade of the needle plate until the thread is cut, ensuring that the starting thread end remaining on the fabric is short enough, thus solving the problem of bird's nest-like stitches at the beginning of existing garment sewing.

[0011] In the aforementioned anti-bird nest mechanism of a sewing machine, the end of the thread guide hole that communicates with the needle hole is straight, the other end of the thread guide hole is arc-shaped, and the middle of the thread guide hole is trumpet-shaped; or the thread guide hole is Z-shaped. This allows the thread to move more effectively from the needle hole into the thread guide hole and be cut by the blade of the thread cutter, while also preventing accidental cutting during normal sewing.

[0012] In the aforementioned bird nest prevention mechanism for a sewing machine, the cutting edge of the thread cutter is integrally formed on the inner end wall of the thread guide hole away from the needle hole; or the thread cutter is fixed to the lower surface of the needle plate, and the cutting edge of the thread cutter is located directly below the end of the thread guide hole away from the needle hole; or the thread cutter is fixed to the upper surface of the needle plate, and the cutting edge of the thread cutter is located directly above the end of the thread guide hole away from the needle hole, and the upper surface of the thread cutter is flush with the upper surface of the needle plate. Depending on the user's actual needs, the thread cutter can adopt an integrally formed or separately fixed structure.

[0013] In the aforementioned anti-bird nest mechanism for a sewing machine, the mechanism further includes a suction pipe fixed to the machine base. The thread-grabbing hole is an elongated arc shape extending along the front-rear direction of the machine base, and the end of the thread-grabbing hole furthest from the fixed blade is positioned opposite to the suction port of the suction pipe. The suction pipe can promptly suck away any loosened thread ends (that have been cut), preventing the thread ends from tangling and reforming into a bird's nest-like ball of yarn.

[0014] In the aforementioned anti-bird nest mechanism for a sewing machine, the mechanism further includes a cutter holder and a swing seat, each mounted on the machine base and capable of rotating up and down around a rotary hook. The cutter holder has a first mounting protrusion, and the thread-cutting blade is fixedly connected to the first mounting protrusion. The swing seat has a second mounting protrusion, and the pressure plate is fixedly connected to the second mounting protrusion. When the cutter holder swings downwards, the first mounting protrusion pushes the second mounting protrusion, causing the swing seat to swing downwards synchronously. An elastic element is also provided between the swing seat and the machine base. When the cutter holder swings upwards, the swing seat swings upwards to its original position under the action of the elastic element. This allows the swing seat to swing downwards and upwards under the action of the cutter holder and the elastic element, respectively, eliminating the need for an additional power mechanism and simplifying the structure.

[0015] Compared with existing technologies, the advantages of the anti-bird nest mechanism of this sewing machine are: the thread cutting position of the anti-bird nest mechanism is closer to the needle hole of the needle plate, which ensures that the thread end remaining on the sewing fabric is short enough, thereby solving the problem of bird nest-like stitches at the starting point in existing garment sewing. Attached Figure Description

[0016] Figure 1This is a three-dimensional structural diagram of the anti-bird nest mechanism of this sewing machine during use.

[0017] Figure 2 This is a three-dimensional structural diagram of the anti-bird nest mechanism of this sewing machine after removing the machine base and the thread-cutting blade.

[0018] Figure 3 This is a three-dimensional structural diagram of the anti-bird nest mechanism of this sewing machine, including the rotary hook, knife holder, swing seat, thread cutting blade, and pressure plate.

[0019] Figure 4 This is a front view structural diagram of the anti-bird nest mechanism of this sewing machine, including the rotary hook, knife holder, swing seat, fixed thread cutter, moving thread cutter, and pressure plate.

[0020] Figure 5 This is a schematic diagram of the needle plate of the anti-bird nest mechanism of the sewing machine in Embodiment 1.

[0021] Figure 6 This is a schematic diagram of the needle plate structure of the anti-bird nest mechanism of this sewing machine in Embodiment 2.

[0022] Figure 7 This is a schematic diagram of the structure of the anti-bird nest mechanism needle plate of the sewing machine in Embodiment 3, which features an integrated thread cutter.

[0023] Figure 8 This is a schematic diagram of the structure of the anti-bird nest mechanism needle plate of the sewing machine in Embodiment 3, which features a split-type thread cutter.

[0024] Figure 9 This is a schematic diagram of the anti-bird nest mechanism of this sewing machine when the needle is about to be cut.

[0025] In the diagram, 1 is the machine base; 2 is the needle plate; 2a is the needle hole; 2b is the thread guide hole; 3 is the rotary hook; 4 is the fixed thread cutter; 5 is the moving thread cutter; 5a is the thread gripping hole; 6 is the pressure plate; 7 is the thread cutter; 8 is the suction pipe; 8a is the suction port; 9 is the knife holder; 9a is the first mounting protrusion; 10 is the swing seat; 10a is the second mounting protrusion; 11 is the elastic element; 12 is the needle; 13 is the sewing material; and 14 is the top thread. Detailed Implementation

[0026] 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.

[0027] Example 1

[0028] A bird nest prevention mechanism for a sewing machine, as shown in the reference. Figure 1-5 and Figure 7The sewing machine includes a base 1, a needle plate 2 with a needle hole 2a disposed on the upper surface of the base 1, and a rotary hook 3 and a thread cutter 4 disposed below the needle plate 2. The anti-bird nest mechanism includes a thread cutter 5 disposed below the needle plate 2 and capable of rotating up and down around the rotary hook 3. The thread cutter 5 has a thread gripping hole 5a for the needle 12 to pass through. The anti-bird nest mechanism also includes a thread pressing plate 6 disposed outside the thread cutter 5 and capable of rotating up and down around the rotary hook 3. The thread cutter 5 can adhere to the thread pressing plate 6 and drive the thread pressing plate 6 to swing in the same direction. The needle plate 2 has a thread passage hole 2b located in front of the thread cutter 4 and connected to the needle hole 2a. The needle plate 2 also has a thread cutter 7 integrally formed thereon. The blade of the thread cutter 7 is positioned facing the needle hole 2a and located inside the thread passage hole 2b.

[0029] Specifically, the end of the thread-passing hole 2b that communicates with the pinhole 2a is straight, the other end of the thread-passing hole 2b is arc-shaped, and the middle part of the thread-passing hole 2b is trumpet-shaped. In this embodiment, preferably, the blade of the thread cutter 7 is integrally formed on the arc-shaped inner wall of the thread-passing hole 2b.

[0030] This bird nest prevention mechanism also includes a suction pipe 8 fixed to the base 1. The wire gripping hole 5a is an elongated arc shape opened along the front-back direction of the base 1. The end of the wire gripping hole 5a away from the wire cutting blade 4 can be arranged opposite to the suction port 8a of the suction pipe 8.

[0031] This bird nest prevention mechanism also includes a cutter holder 9 and a swing seat 10, which are respectively mounted on the base 1 and can rotate up and down around the rotary shuttle 3. The cutter holder 9 has a first mounting protrusion 9a, and the wire cutting blade 5 is fixedly connected to the first mounting protrusion 9a. The swing seat 10 has a second mounting protrusion 10a, and the wire pressing piece 6 is fixedly connected to the second mounting protrusion 10a. When the cutter holder 9 swings downward, the first mounting protrusion 9a of the cutter holder 9 can drive the swing seat 10 to swing downward synchronously by pushing the second mounting protrusion 10a. An elastic element 11 is also provided between the swing seat 10 and the base 1. When the cutter holder 9 swings upward, the swing seat 10 can swing upward and return to its original position under the action of the elastic element 11.

[0032] The working principle of the bird nest prevention mechanism of this sewing machine is explained below:

[0033] At the start of sewing, the larger end of the thread-grabbing hole 5a of the moving thread cutter 5 (i.e., the end furthest from the fixed thread cutter 4) is directly below the needle 12. The needle 12 pulls the top thread 14 into the thread-grabbing hole 5a. As the needle 12 begins to rise, the top thread 14 forms a small loop under the fabric 13. The tip of the rotary hook 3 passes through the small loop, bringing the top thread 14 completely below the moving thread cutter 5.

[0034] As the needle 12 moves upward away from the thread gripping hole 5a, the thread-cutting blade 5 moves towards the pressure plate 6. During the movement of the thread-cutting blade 5, the thread 14 is pressed against the leading edge of the pressure plate 6, thus sliding within the thread gripping hole 5a until it reaches the small end of the thread gripping hole 5a (i.e., the end near the fixed thread-cutting blade 4), and is finally pressed by the pressure plate 6 onto the arc surface of the thread-cutting blade 5 near the small end. The initial position of the pressure plate 6 is determined by the fixed position of the elastic element 11 and the machine base 1.

[0035] The thread-cutting blade 5 remains stationary and continues sewing several stitches. Afterward, the thread-cutting blade 5 continues to swing towards the pressure plate 6. Since there is no gap between the first mounting protrusion 9a of the blade holder 9 and the second mounting protrusion 10a of the swing seat 10, the first mounting protrusion 9a of the blade holder 9 can push the second mounting protrusion 10a to drive the swing seat 10 to swing downward synchronously, thereby maintaining the state of the thread 14 clamped between the thread-cutting blade 5 and the pressure plate 6.

[0036] The thread-cutting blade 5 and the pressure plate 6 clamp the top thread 14 and move it away from the needle 12, i.e., swing it downwards. Simultaneously, during sewing, the fabric 13 is pushed forward by the feeding device towards the machine base 1. Together, they move the top thread end towards the blade of the thread-cutting blade 7 on the needle plate 2 until the top thread 14 is cut. This ensures that the remaining starting thread end on the fabric 13 is short enough, thus solving the problem of bird's nest-like stitches at the starting point in existing garment sewing. Afterwards, the thread-cutting blade 5 and the pressure plate 6 hold the cut top thread 14 still until the sewing is finished and the tail thread is cut.

[0037] When the sewing is finished and the thread is trimmed, the moving thread cutter 5 begins to move towards the fixed thread cutter 4. At this time, the moving thread cutter 5 begins to separate from the presser plate 6, and the clamped thread end is released. The suction device starts to work and sucks away the released thread end through the suction pipe 8. The moving thread cutter 5 finally engages with the fixed thread cutter 4, cutting the thread on the sewing material 13, ending the sewing, and stopping the thread-grabbing hole 5a of the moving thread cutter 5 directly below the needle 12 for the next sewing.

[0038] Example 2

[0039] This embodiment is basically the same in structure and principle as Embodiment 1, the difference being: (Refer to...) Figure 6 The needle plate 2 is also connected to a thread cutter 7. The blade of the thread cutter 7 is positioned facing the needle hole 2a and directly below the thread passage hole 2b. Specifically, the thread cutter 7 is fixed to the lower surface of the needle plate 2, and the blade of the thread cutter 7 is located directly below the end of the thread passage hole 2b away from the needle hole 2a. Preferably, the thread cutter 7 is fixed to the lower surface of the needle plate 2 by bolts.

[0040] Example 3

[0041] This embodiment is basically the same in structure and principle as Embodiment 1, the difference being: (Refer to...) Figure 7 and Figure 8 The wire hole 2b is Z-shaped, and in addition... Figure 8 In this configuration, the thread cutter 7 is fixedly connected to the upper surface of the needle plate 2, and the blade of the thread cutter 7 is located directly above the end of the thread hole 2b away from the needle hole 2a. The upper surface of the thread cutter 7 is flush with the upper surface of the needle plate 2.

[0042] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model 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 this utility model or exceeding the scope defined by the appended claims.

Claims

1. A bird nest prevention mechanism for a sewing machine, the sewing machine comprising a machine base (1), a needle plate (2) disposed on the upper surface of the machine base (1) and having needle holes (2a), and a rotary hook (3) and a thread-cutting fixed blade (4) respectively disposed below the needle plate (2), the bird nest prevention mechanism comprising a thread-cutting movable blade (5) disposed below the needle plate (2) and capable of rotating up and down around the rotary hook (3), characterized in that, The moving wire cutter (5) has a wire-grabbing hole (5a) for the needle (12) to pass through. The anti-bird nest mechanism also includes a pressure plate (6) located on the outside of the moving wire cutter (5) and capable of rotating up and down around the rotary hook (3). The moving wire cutter (5) can be attached to the pressure plate (6) and drive the pressure plate (6) to swing in the same direction. The needle plate (2) has a thread-passing hole (2b) located in front of the fixed wire cutter (4) and connected to the needle hole (2a). The needle plate (2) is also connected to a wire cutter (7). The blade of the wire cutter (7) is set facing the needle hole (2a) and located directly above or directly below the thread-passing hole (2b); or the needle plate (2) is also integrally formed with a wire cutter (7). The blade of the wire cutter (7) is set facing the needle hole (2a) and located inside the thread-passing hole (2b).

2. The anti-bird nest mechanism for a sewing machine according to claim 1, characterized in that, The end of the wire hole (2b) that connects to the pinhole (2a) is straight, the other end of the wire hole (2b) is arc-shaped, and the middle part of the wire hole (2b) is trumpet-shaped; or the wire hole (2b) is Z-shaped.

3. The anti-bird nest mechanism for a sewing machine according to claim 2, characterized in that, The cutting edge of the thread cutter (7) is integrally formed on the inner end wall of the thread passage hole (2b) away from the needle hole (2a); or the thread cutter (7) is fixedly connected to the lower surface of the needle plate (2), and the cutting edge of the thread cutter (7) is located directly below the end of the thread passage hole (2b) away from the needle hole (2a); or the thread cutter (7) is fixedly connected to the upper surface of the needle plate (2), and the cutting edge of the thread cutter (7) is located directly above the end of the thread passage hole (2b) away from the needle hole (2a), and the upper surface of the thread cutter (7) is flush with the upper surface of the needle plate (2).

4. A bird nest prevention mechanism for a sewing machine according to claim 1, 2, or 3, characterized in that, This bird nest prevention mechanism also includes a suction pipe (8) fixed to the base (1). The wire gripping hole (5a) is an elongated arc shape opened along the front and rear direction of the base (1). The end of the wire gripping hole (5a) away from the wire cutting blade (4) can be arranged opposite to the suction port (8a) of the suction pipe (8).

5. A bird nest prevention mechanism for a sewing machine according to claim 1, 2, or 3, characterized in that, This bird nest prevention mechanism also includes a cutter holder (9) and a swing seat (10) respectively mounted on the base (1) and both capable of rotating up and down around the rotary hook (3). The cutter holder (9) has a first mounting protrusion (9a), and the wire cutting blade (5) is fixedly connected to the first mounting protrusion (9a). The swing seat (10) has a second mounting protrusion (10a), and the wire pressing piece (6) is fixedly connected to the second mounting protrusion (10a). When the cutter holder (9) swings downward, the first mounting protrusion (9a) of the cutter holder (9) can drive the swing seat (10) to swing downward synchronously by pushing the second mounting protrusion (10a). An elastic element (11) is also provided between the swing seat (10) and the base (1). When the cutter holder (9) swings upward, the swing seat (10) can swing upward and reset under the action of the elastic element (11).

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