Bird nest prevention device for a sewing machine

Abstract

The utility model provides a kind of bird nest prevention device of sewing machine, including cabinet and rotating shuttle, further including first thread cutting moving knife and second thread cutting moving knife, first thread cutting moving knife is equipped with the first needle hole cooperation with needle, first moving knife cutting edge, cabinet is located rotating shuttle side is equipped with the first fixed knife cooperation with first thread cutting moving knife, for cutting face thread end, other side is equipped with the second fixed knife cooperation with second thread cutting moving knife, for cutting face thread and ground thread, first thread cutting moving knife includes: first position satisfies needle can be from first needle hole needle, face thread end is brought to first needle hole below and is clamped at first needle hole;Second position satisfies face thread end is driven to the first thread cutting moving knife between first moving knife cutting edge and the first fixed knife of first fixed knife cutting edge but is not cut off;Third position satisfies needle at least needle twice, first moving knife cutting edge and the blade of first fixed knife engage and cut off face thread end.The utility model can prevent bird nest phenomenon, more beautiful.

Description

Technical Field

[0001] This utility model relates to the field of sewing machine technology, and in particular to a bird nest prevention device for sewing machines. Background Technology

[0002] A sewing machine is a machine that uses one or more sewing threads to create one or more stitches on fabric, interweaving or sewing together one or more layers of fabric. Sewing machines can sew fabrics such as cotton, linen, silk, wool, and synthetic fibers, as well as products made of leather, plastic, and paper. The stitches produced are neat, beautiful, flat, and strong. Sewing speed is fast and the machine is easy to use. The "bird's nest" phenomenon refers to the situation where, when starting to sew, the top thread remains on the presser foot, resulting in a clump of thread at the beginning of the stitch. This severely affects the appearance and sewing quality of the product. To avoid the bird's nest phenomenon, anti-bird's nest structures are usually used. Utility Model Content

[0003] To address the problems of the prior art, this invention provides an anti-bird nest device for sewing machines, which can cut the thread under the fabric by inserting the needle, thus preventing bird nest formation.

[0004] The technical solution adopted is as follows: A bird nest prevention device for a sewing machine includes a machine housing and a rotary hook, and further includes a first and a second thread-cutting blade mounted on a thread-cutting blade holder and rotatable around the rotary hook. The first thread-cutting blade has a first needle hole for cooperating with a needle, a first blade edge, and a first thread-receiving groove connecting the first blade edge and the first needle hole. The machine housing has a first fixed blade on one side of the rotary hook that cooperates with the first thread-cutting blade for cutting the top thread end, and a second fixed blade on the other side that cooperates with the second thread-cutting blade for cutting the top and bottom threads. The machine housing also... The device includes a suction structure for absorbing the thread end. The first thread-cutting blade has three positions: a first position, a second position, and a third position. The first position allows the needle to enter through the first needle hole, bringing the thread end below the first needle hole and locking it there. The second position allows the thread end to be moved by the first thread-cutting blade to the space between the first moving blade edge and the first fixed blade edge of the first fixed blade, but without being cut off. The third position allows the needle to enter at least twice before the first moving blade edge and the first fixed blade edge engage to cut off the thread end.

[0005] Furthermore, it also includes a drive structure that drives the wire cutter holder to rotate, enabling the first and second wire cutters to complete the wire cutting action.

[0006] Furthermore, a wire clamping spring for holding the thread end is provided at the corresponding location of the first lower needle hole, and the wire clamping spring is located in the first thread receiving groove.

[0007] Furthermore, the wire clamping spring includes two cooperating elastic wire clamping arms, and the wire clamping spring has a ring opening at the first lower needle hole.

[0008] Furthermore, the air intake structure includes a connector for connecting to an external air pipe, and the connector is provided with an air intake hole, which is oriented toward the first wire-cutting blade.

[0009] Furthermore, the second moving wire cutter includes a second lower needle hole, a second wire receiving groove, and a second moving blade edge, wherein the second moving blade edge cooperates with the blade edge of the second fixed blade.

[0010] Furthermore, the drive structure includes a drive motor and a transmission shaft, with a synchronous belt pulley assembly between the transmission shaft and the drive motor, and a gear transmission assembly between the transmission shaft and the wire shear holder.

[0011] Furthermore, when the first moving blade is in the second position, the distance between the first moving blade edge and the first fixed blade edge is 1-1.5mm.

[0012] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention provides an anti-bird's nest device for sewing machines. A first thread-cutting blade is added around the rotary hook to cut the thread end. A first fixed blade is provided on the machine housing to cooperate with the first thread-cutting blade. The needle brings the thread end to the first thread-cutting blade. The thread end is cut off by the rotation of the first thread-cutting blade and its cooperation with the first fixed blade. This prevents the thread from being too long and piling up, thus preventing the bird's nest phenomenon when sewing fabric and making the product more aesthetically pleasing. Attached Figure Description

[0013] Figure 1 , 2 Schematic diagrams of two different angles for the first shearing blade in the first position; Figure 3 This is a schematic diagram of the overall structure of this utility model; Figure 4 for Figure 3 Enlarged view at point a; Figure 5 A schematic diagram showing the first wire-cutting blade in the second position; Figure 6 A schematic diagram showing the first wire-cutting blade in the third position; Figure 7 A schematic diagram showing the structure with the second shearing blade positioned at the top; Figure 8 This is a schematic diagram showing the needle positioned above the fabric in the initial state. Figure 9 This is a diagram illustrating the first insertion of the needle. Figure 10 This is a schematic diagram of the first return stroke of the needle. Figure 11This is a schematic diagram showing the first wire-cutting blade rotating to the second position; Figure 12 This is a diagram illustrating the second insertion of the needle. Figure 13 for Figure 1 Enlarged view at point b; Figure 14 A schematic diagram of the first wire-cutting blade and the wire-clamping spring; The components include: housing 1, first moving wire cutter 2, first lower needle hole 201, first moving blade edge 202, first wire receiving groove 203, second moving wire cutter 3, second lower needle hole 301, second wire receiving groove 302, second moving blade edge 303, wire cutter holder 4, needle 5, wire clamping spring 6, elastic wire clamping arm 601, drive structure 7, drive motor 701, transmission shaft 702, synchronous belt pulley assembly 703, gear transmission assembly 704, air intake structure 8, connector 801, air hole 802, ring opening 9, first fixed blade 10, first fixed blade edge 1001, second fixed blade 11, drive shaft 12, and rotary hook 13. Detailed Implementation

[0014] The present invention will be further described below with reference to specific embodiments.

[0015] refer to Figure 1-14 A bird nest prevention device for a sewing machine includes a machine housing 1 and a rotary hook 10, and further includes a first thread-cutting blade 2 and a second thread-cutting blade 3 mounted on a thread-cutting blade holder 4 and capable of rotating around the rotary hook. The first thread-cutting blade 2 has a first lower needle hole 201 that mates with a needle 5, a first moving blade edge 202, and a first thread-receiving groove 203 connecting the first moving blade edge and the first lower needle hole. The machine housing 1 has a first fixed blade 10 on one side of the rotary hook that mates with the first thread-cutting blade 2 for cutting the thread ends, and a second fixed blade 1 on the other side that mates with the second thread-cutting blade 3 for cutting the top and bottom threads. 1. The housing 1 is further provided with a suction structure 8 for absorbing the thread end. The first thread-cutting blade 2 includes a first position, a second position, and a third position. The first position satisfies the requirement that the needle can enter from the first needle hole 201, bringing the thread end to the bottom of the first needle hole and locking it in the first needle hole. The second position satisfies the requirement that the thread end is driven by the first thread-cutting blade to the area between the first moving blade edge 202 and the first fixed blade edge 10 but is not cut off. The third position satisfies the requirement that after the needle enters at least twice, the first moving blade edge and the first fixed blade edge engage to cut off the thread end.

[0016] It also includes a drive structure 7 that drives the wire cutter holder 4 to rotate, so that the first wire cutter 2 and the second wire cutter 3 can complete the wire cutting action.

[0017] like Figure 8In the initial state, the first thread-cutting blade 2 is in the first position, the needle 5 is suspended above the first lower needle hole 201, and the needle is threaded with a top thread. One end of the top thread is connected to the thread ball, and the other end is a free end, i.e., the top thread head. Figure 9 When the needle 5 begins sewing, it pierces the fabric, passing through the first needle hole 201. When the needle is at the lower end of the first needle hole 201, it brings the top thread end under the fabric and below the first thread-cutting blade 2 (at this point, the top thread end may not be completely under the fabric; if the top thread end is too long, some may still remain on top of the fabric). Then, the rotary hook rotates to hook the top thread and the bobbin thread together for the first time (because the top thread end is free, the bobbin thread may not be able to hook and lock the top thread). Figure 10 Simultaneously, the needle moves upward and stops when it reaches a certain distance above the needle plate. At this point, the top thread end is completely or partially left under the fabric, while the needle returns to the top of the fabric with the other end of the top thread.

[0018] like Figure 11 The driving structure 7 drives the thread-cutting blade holder 4 to rotate towards the first fixed blade 10, rotating to the second position. Preferably, when the first moving thread-cutting blade 2 is in the second position, the distance between the first moving blade edge 202 and the first fixed blade edge 1001 is 1-1.5mm. The rotation of the first moving thread-cutting blade 2 will cause the thread head to move together. The thread head can be in the thread groove. If the thread head is too long, as the first moving thread-cutting blade 2 rotates, the part of the thread head above the fabric will gradually detach from the fabric and be completely below the fabric. When the first moving thread-cutting blade 2 rotates to the second position, it can cooperate with the suction structure 8. The suction structure 8 can suck up the thread head, and since the first moving thread-cutting blade 2 is below the first fixed blade 10, the thread head will always be below the first fixed blade, stuck between the first fixed blade edge and the second moving blade edge, but not cut off. Figure 12 At this point, the needle 5 will needle down at least once more, the shuttle will rotate, and the bottom and top threads will hook together again. Preferably, the needle will needle down twice more, hooking the threads twice to ensure that the bottom and top threads are hooked together and fixed, thus ensuring the stability of the sewing.

[0019] After the needle 5 returns to the needle plate seat, the drive structure 7 continues to drive the thread cutter holder 4 to rotate towards the first fixed blade 10. When it reaches the third position, the first moving blade edge 202 engages with the first fixed blade edge 1001 to cut the thread end. At this point, there will be no excessively long thread ends under the fabric, preventing thread accumulation and solving the "bird's nest" problem.

[0020] The second thread-cutting blade 3 includes a second lower needle hole 301, a second thread-receiving groove 302, and a second moving blade edge 303, which engages with the blade edge of the second fixed blade. After the top thread is cut, the needle continues sewing. When sewing is complete and thread cutting is required, the drive structure 7 drives the second thread-cutting blade 3 to rotate and engage with the second fixed blade 11, completing the cutting of the top and bottom threads. This structure and process can refer to existing technology.

[0021] Preferably, a clamping spring 6 for holding the thread end is provided at the corresponding location of the first lower needle hole 201, and the clamping spring 6 is disposed within the first thread receiving groove 203. The clamping spring 6 includes two cooperating elastic clamping arms 601, and the clamping spring 6 has an annular opening 9 at the first lower needle hole 201. The thread end is inserted into the two elastic clamping arms 601 through the gap of the annular opening 9, which serves to fix and absorb the thread end. For shorter thread ends, which are not easily sucked up by the suction structure 8, the clamping spring 6 provides a better effect in fixing the thread end.

[0022] The suction structure 8 includes a connector 801 that connects to an external air pipe. The connector 801 is provided with a suction hole 802, which is oriented toward the first thread-cutting blade 2 to facilitate the suction of thread ends.

[0023] The drive structure 7 includes a drive motor 701 and a transmission shaft 702. A synchronous belt pulley assembly 703 is provided between the transmission shaft 702 and the drive motor 701, and a gear transmission assembly 704 is provided between the transmission shaft 702 and the wire cutter holder 4. The wire cutter holder 4 is mounted on a drive shaft 12 and rotates. The drive motor 701 drives the transmission shaft 702 to rotate via the synchronous belt pulley assembly 703, and the rotation of the transmission shaft 702 drives the wire cutter holder 4 to rotate via the gear transmission assembly 704.

[0024] The above description is only an optional embodiment of the present utility model and does not limit the patent scope of the present utility model. All equivalent structural transformations made under the inventive concept of the present utility model using the contents of the present utility model specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present utility model.

Claims

1. A bird nest prevention device for a sewing machine, comprising a housing (1) and a rotary hook (13), characterized in that: It also includes a first thread-cutting blade (2) and a second thread-cutting blade (3) mounted on the thread-cutting blade holder (4) and capable of rotating around the rotary hook. The first thread-cutting blade (2) is provided with a first lower needle hole (201) that cooperates with the needle (5), a first moving blade edge (202), and a first thread-receiving groove (203) connecting the first moving blade edge and the first lower needle hole. The machine housing (1) is provided with a first fixed blade (10) on one side of the rotary hook that cooperates with the first thread-cutting blade (2) and is used for cutting the thread head. On the other side, it is provided with a second fixed blade (11) that cooperates with the second thread-cutting blade (3) and is used for cutting the thread head and the bottom thread. The upper part is also provided with a suction structure (8) for absorbing the thread end. The first thread-cutting blade (2) includes a first position, a second position and a third position. The first position satisfies that the needle can be inserted from the first needle hole (201) and the thread end is brought to the bottom of the first needle hole and stuck in the first needle hole. The second position satisfies that the thread end is driven by the first thread-cutting blade to the space between the first moving blade edge (202) and the first fixed blade edge (1001) of the first fixed blade (10) but is not cut off. The third position satisfies that after the needle inserts at least twice, the first moving blade edge and the first fixed blade edge engage to cut off the thread end.

2. The anti-bird nest device for a sewing machine as described in claim 1, characterized in that: It also includes a drive structure (7) that drives the wire cutter holder (4) to rotate and enables the first wire cutter (2) and the second wire cutter (3) to complete the wire cutting action.

3. The anti-bird nest device for a sewing machine as described in claim 1, characterized in that: The first lower needle hole (201) is provided with a wire clamping spring (6) for clamping the thread end, and the wire clamping spring (6) is provided in the first wire receiving groove (203).

4. The anti-bird nest device for a sewing machine as described in claim 3, characterized in that: The wire clamping spring (6) includes two mutually cooperating elastic wire clamping arms (601), and the wire clamping spring (6) is provided with a ring opening (9) at the first lower needle hole (201).

5. The anti-bird nest device for a sewing machine as described in claim 1, characterized in that: The air intake structure (8) includes a connector (801) for connecting to an external air pipe. The connector (801) is provided with an air intake hole (802), which is oriented toward the first wire cutting blade (2).

6. The anti-bird nest device for a sewing machine as described in claim 1, characterized in that: The second moving wire cutter (3) includes a second lower needle hole (301), a second wire receiving groove (302), and a second moving blade edge (303), wherein the second moving blade edge (303) cooperates with the blade edge of the second fixed blade.

7. The anti-bird nest device for a sewing machine as described in claim 2, characterized in that: The drive structure (7) includes a drive motor (701) and a transmission shaft (702). A synchronous belt pulley assembly (703) is provided between the transmission shaft (702) and the drive motor (701), and a gear transmission assembly (704) is provided between the transmission shaft (702) and the wire cutter holder (4).

8. The bird nest prevention device for a sewing machine as described in claim 2, characterized in that: When the first moving shear blade (2) is in the second position, the distance between the first moving blade edge (202) and the first fixed blade edge (1001) is 1-1.5mm.

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