Bird nest preventing mechanism of sewing machine

Abstract

The utility model provides a bird nest preventing mechanism of a sewing machine, and belongs to the technical field of sewing machines. The technical problem that an anti-nest mechanism of an existing sewing machine is low in operation efficiency and unstable is solved. According to the bird nest preventing mechanism of the sewing machine, the sewing machine comprises a machine base, a rotating shuttle connected to the machine base and a first fixed cutter, the bird nest preventing mechanism comprises a movable cutter capable of doing reciprocating motion around the periphery of the rotating shuttle, and a thread containing groove capable of limiting an upper thread inside through downward airflow is formed in the movable cutter. The machine base is further fixedly connected with a second fixed cutter opposite to the first fixed cutter, the outer end of the second fixed cutter abuts against the surface of a movable cutter, closest to the first fixed cutter, of the thread containing groove, and when the movable cutter moves towards the first fixed cutter and shears with the first fixed cutter, the machine needle can be right opposite to the thread containing groove below. According to the utility model, the anti-nest operation efficiency and stability can be improved.

Description

Technical Field

[0001] The utility model belongs to the technical field of sewing machines and relates to a bird nest prevention mechanism of a sewing machine. Background Art

[0002] The existing sewing thread cutting structure is a movable knife and a fixed knife located below the needle plate and above the rotary shuttle. The fixed knife is fixed on the sewing machine base. The movable knife is driven by a driving mechanism and rotates around the lower shaft. The tip of the movable knife separates the upper thread loop and moves the suture toward the fixed knife. On the side of the machine needle, the movable knife and the fixed knife perform high-pressure mechanical bite to cut the suture. Due to the mechanical bite thread cutting, the residual thread ends on the sewn product after thread cutting are too long and unstable, and the residual upper thread ends left on the side of the machine needle are unstable in length. The long thread ends remaining on the sewn product require an additional manual thread trimming process; the unstable upper thread ends form a bird's nest in the first few stitches of the next sewing, affecting the quality of the sewn product. The suction device is one of the extremely important additional devices in the sewing machine, which is mainly used to collect impurities such as thread ends and rags. At present, the suction device is divided into two categories, one is a pneumatic suction device coordinated with an external air source, and the other is an electric suction device driven by a motor.

[0003] As for the air suction device, Chinese patent 201510298016.X discloses a dust collection device for a sewing machine, which includes a dust collecting bucket, which is provided with an upper cover plate; the upper cover plate is provided with a dust suction rear port and a thread suction tube connection port; the inner cavity of the dust collecting bucket is provided with a motor, and the output shaft of the motor is connected to the fan; the outside or the inner cavity of the dust collecting bucket is provided with an electromagnet, one end of the electromagnet forms a clamping arm, the clamping arm is fixedly connected to a connecting pin, the connecting pin is connected to the free end of a rotating part, the fixed end of the rotating part is provided with a fixing pin, and the connecting pin can rotate around the fixing pin; the connecting pin is fixedly connected to a partition; the electromagnet drives the clamping arm to be ejected, the clamping arm drives the connecting pin to rotate around the fixing pin, and the connecting pin drives the partition to rotate accordingly, so as to cover the dust suction rear port.

[0004] In addition, the patent application publication number CN115679562A discloses a thread trimming mechanism of a sewing machine, including a thread trimming mechanism, a needle plate, and teeth. The thread trimming mechanism is provided with an active knife and a fixed knife; the active knife is provided with a groove surface, a convex surface and an inclined surface, and the cutting edge is provided at the connection between the groove surface and the convex surface.

[0005] The above structure discloses an existing wire cutting mechanism, which cooperates with an air suction device to collect the broken wires after the wire heads are manually cut, but its anti-bird nest operation efficiency is low and unstable. Summary of the invention

[0006] The utility model aims at the above problems existing in the prior art and provides an anti-bird nest mechanism for a sewing machine. The technical problem to be solved by the utility model is: how to improve the anti-bird nest effect of the sewing machine.

[0007] The purpose of the utility model can be achieved through the following technical solutions:

[0008] A bird's nest prevention mechanism for a sewing machine, the sewing machine comprising a machine base, a rotary hook connected to the machine base and a first fixed knife, the bird's nest prevention mechanism comprising a movable knife that can reciprocate around the periphery of the rotary hook, characterized in that the movable knife is provided with a thread containing groove that can confine the surface thread through downward airflow, and the machine base is also fixedly connected to a second fixed knife located opposite the first fixed knife, the outer end of the second fixed knife is in conflict with the movable knife surface of the thread containing groove closest to the first fixed knife, and when the movable knife moves toward the first fixed knife and forms a shear with the first fixed knife, the machine needle can be directly opposite to the thread containing groove below.

[0009] The rotary shuttle is used to hook the thread and loop it to achieve sewing by rotating, and it can be an existing component. The first fixed knife can cooperate with the moving knife to achieve a thread cutting effect; by providing a thread accommodating groove that can form a downward airflow on the moving knife, the airflow in the thread accommodating groove can be achieved by arranging an existing suction device under the moving knife, and a second fixed knife opposite to the first fixed knife is provided on the machine base, so that the outer end of the second fixed knife is in contact with the surface of the moving knife at the position of the thread accommodating groove closest to the first fixed knife, and at the same time, when the moving knife and the first fixed knife form shearing, the machine needle can be lowered into the thread accommodating groove, and the suction device can suck the area between the bottom of the thread accommodating groove and the rotary shuttle, so that after the machine needle is lowered to the thread accommodating groove, the rotary shuttle can hook the upper thread, and when the needle rises, the moving knife begins to reset and the upper thread is adsorbed and held in the thread accommodating groove. The moving knife continues to reset and the second fixed knife will slide to the edge of the thread accommodating groove closest to the first fixed knife to form automatic shearing and then self-form a shorter needle thread end, thereby achieving an automatic anti-bird's nest effect and improving operating efficiency and stability.

[0010] In the anti-bird nest mechanism of the sewing machine, the outer end of the second fixed knife is tilted upward, so that the outer end of the second fixed knife can generate a larger elastic deflection space toward the surface of the movable knife, which is conducive to ensuring the continuous and stable contact effect between the outer end of the second fixed knife and the movable knife, thereby maintaining a reliable thread cutting effect.

[0011] In the anti-bird nest mechanism of the sewing machine, a clearance groove is provided on the outer end of the second fixed knife facing the side of the rotary hook, which is conducive to reducing the contact surface between the second fixed knife and the moving knife surface, avoiding the impact on the continuous contact between the edge of the second fixed knife and the moving knife surface, and ensuring the stability of thread cutting.

[0012] In the anti-bird nest mechanism of the sewing machine, the second fixed knife and the first fixed knife are staggered along the axial direction of the rotary hook, the side of the movable knife close to the first fixed knife has a cutting knife groove arranged in a strip shape along the circumferential direction and the edge can form a shear with the first fixed knife, and the edge of the thread accommodating groove closest to the first fixed knife is opposite to the middle section of the cutting knife groove along the axial direction of the rotary hook. This is conducive to more fully utilizing the circumferential dimension space of the movable knife, so that the upper thread is closer to the sewing position when being cut, further reducing the length of the needle thread, and improving the anti-bird nest effect.

[0013] In the anti-bird nest mechanism of the sewing machine, the side of the movable knife away from the first fixed knife has a chamfered surface, and the chamfered surface is engaged with the inner edge surface of the wire accommodating groove. When the movable knife and the first fixed knife form a shearing fit, the movable knife may have been out of the range of the second fixed knife, which is conducive to the chamfered surface guiding the second fixed knife and the movable knife to slide dislocated when the movable knife is reset, so as to avoid the two from being damaged by hard interference.

[0014] In the anti-bird nest mechanism of the sewing machine, the thread accommodating groove is in an arc shape along the surface of the movable knife, and the inner edge surface of the thread accommodating groove is processed with smooth transition. This is conducive to ensuring that the upper thread can slide smoothly along the inner edge of the thread accommodating groove, and ensuring that the upper thread can slide to the area closest to the first fixed knife when the movable knife is reset to form a cut thread.

[0015] In the anti-bird nest mechanism of the sewing machine, a stepper motor, an intermediate shaft and a lower shaft for driving the rotary hook to rotate are arranged in the machine base, the intermediate shaft is rotatably connected in the machine base and is parallel to the stepper motor and the lower shaft, the outer sleeve of the lower shaft is provided with a swing arm fixedly connected to the moving knife, the outer periphery of the swing arm is hinged with the outer periphery of one end of the intermediate shaft through a crank rod, the output end of the stepper motor is fixedly connected with a swing arm, the swing arm is hinged with the outer periphery of the other end of the intermediate shaft through a connecting rod, and when the output end of the stepper motor rotates, it can drive the swing arm to move around the lower shaft. In this way, the stepper motor is used to more accurately control the movement of the moving knife after integrating multiple functions, ensure the movement accuracy, and thus make the anti-bird nest performance more stable.

[0016] In the anti-bird nest mechanism of the sewing machine, a chip cleaning air pipe capable of blowing or sucking air is provided in the machine base, and the end of the chip cleaning air pipe is arranged toward the outer end of the second fixed knife. In this way, the chip cleaning air pipe can clean the residual thread ends after thread cutting by sucking or blowing air during operation.

[0017] Compared with the prior art, the advantages of the utility model are as follows:

[0018] The anti-bird's nest mechanism of the sewing machine can hook the upper thread by the rotary shuttle after the needle goes down to the thread receiving groove. When the needle rises, the movable knife starts to reset and the upper thread in the suction port is adsorbed by the suction device and held in the thread receiving groove. The movable knife continues to reset and the second fixed knife slides to the edge of the thread receiving groove closest to the first fixed knife to automatically shear and then form a shorter needle thread end, thereby achieving automatic anti-bird's nest effect and improving operating efficiency and stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the partial three-dimensional structure of the sewing machine in this embodiment.

[0020] Figure 2 It is a three-dimensional schematic diagram of the local structure of this embodiment.

[0021] Figure 3 It is a front view schematic diagram of the local structure of this embodiment.

[0022] Figure 4 yes Figure 3 Enlarged view of part A in .

[0023] Figure 5 It is a schematic three-dimensional diagram of the local structure of the movable knife and the first fixed knife in the shearing state of this embodiment.

[0024] Figure 6 It is a three-dimensional schematic diagram of the stepping motor transmission structure of this embodiment.

[0025] In the figure, 1, machine base; 2, rotary hook; 3, first fixed knife; 4, lower shaft;

[0026] 5. Moving knife; 51. Wire groove; 52. Cutting knife groove; 53. Chamfered surface;

[0027] 6. Second fixed knife; 61. Make way for cutting groove;

[0028] 7. Stepper motor; 8. Intermediate shaft; 9. Swing arm; 10. Crank arm; 11. Rocker arm; 12. Connecting rod; 13. Chip cleaning air pipe. DETAILED DESCRIPTION

[0029] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0030] like Figure 1-5As shown, in the anti-bird's nest mechanism of the sewing machine, the sewing machine includes a machine base 1, a rotary hook 2 and a first fixed knife 3 connected to the machine base 1, the anti-bird's nest mechanism includes a suction device (not shown) arranged on the machine base 1 and a movable knife 5 that can reciprocate around the periphery of the rotary hook 2, a thread receiving groove 51 is provided on the movable knife 5, and a second fixed knife 6 extending toward the side where the first fixed knife 3 is located is also fixedly connected to the machine base 1, the outer end of the second fixed knife 6 is in conflict with the surface of the movable knife 5 at the thread receiving groove 51 closest to the first fixed knife 3, when the movable knife 5 moves toward the first fixed knife 3 and forms a shear with the first fixed knife 3, the machine needle can be aligned with the thread receiving groove 51 below, and the suction device can suck the area below the thread receiving groove 51 and between the rotary hook 2. The rotary hook 2 is used to hook the thread and loop it through rotation to achieve sewing. It can be an existing component. The first fixed knife 3 can cooperate with the movable knife 5 to achieve the effect of cutting the thread. The principle and structure of the air suction device itself can refer to the existing technology. It can generate negative pressure at the air suction port to clean the broken thread, etc. In this embodiment, the air suction port of the air suction device can be set below the movable knife 5 and close to the rotary hook 2 to ensure that negative pressure is generated below the movable knife 5, or it can be set under the entire rotary hook 2 to form a downward airflow in the cavity of the machine base 1, so that a downward airflow is generated in the thread accommodating groove 51; by arranging the thread accommodating groove 51 on the movable knife 5, and arranging the second fixed knife 6 opposite to the first fixed knife 3 on the machine base 1, the outer end of the second fixed knife 6 is in contact with The thread receiving groove 51 is closest to the surface of the movable knife 5 at the position of the first fixed knife 3. At the same time, when the movable knife 5 and the first fixed knife 3 form shearing, the machine needle can be lowered into the thread receiving groove 51, and the air suction device can suck the area between the lower part of the thread receiving groove 51 and the rotary shuttle 2, so that after the machine needle is lowered to the thread receiving groove 51, the rotary shuttle 2 can hook the surface thread. When the machine needle rises, the movable knife 5 begins to reset and the surface thread in the air suction port is adsorbed and maintained in the thread receiving groove 51 by the air suction device. The movable knife 5 continues to reset, and the second fixed knife 6 will slide to the edge of the thread receiving groove 51 closest to the first fixed knife 3 to form automatic shearing and then self-form a shorter needle thread head, realizing the automatic anti-bird's nest effect and improving the operation efficiency and stability. Specifically, the outer end of the second fixed knife 6 is tilted upward. This is conducive to the outer end of the second fixed knife 6 to generate a larger elastic deflection space toward the surface of the movable knife 5, which is conducive to ensuring the continuous and stable contact effect between the outer end of the second fixed knife 6 and the movable knife 5, thereby maintaining a reliable thread head shearing effect. The outer end of the second fixed knife 6 is provided with a clearance groove 61 on the side facing the rotary shuttle 2. This is conducive to reducing the contact surface between the second fixed knife 6 and the surface of the movable knife 5, avoiding the impact on the continuous contact between the edge of the second fixed knife 6 and the surface of the movable knife 5, and ensuring the thread cutting stability. The second fixed knife 6 and the first fixed knife 3 are staggered along the axial direction of the rotary shuttle 2. The side of the movable knife 5 close to the first fixed knife 3 has a cutting groove 52 that is arranged in a strip shape along the circumferential direction and the edge can form a shear with the first fixed knife 3. The cutting groove 52 is a prior art. The edge of the thread groove 51 closest to the first fixed knife 3 is opposite to the middle section of the cutting groove 52 along the axial direction of the rotary shuttle 2. This is conducive to more fully utilizing the circumferential dimension space of the movable knife 5, so that the surface thread is closer to the sewing position when it is cut, further reducing the length of the needle thread, and improving the anti-bird nest effect.The side of the movable knife 5 away from the first fixed knife 3 has a chamfered surface 53, and the chamfered surface 53 is engaged with the inner edge surface of the wire-containing groove 51. When the movable knife 5 forms a shearing fit with the first fixed knife 3, the movable knife 5 may have been out of the range of the second fixed knife 6. This is conducive to the chamfered surface 53 guiding the second fixed knife 6 and the movable knife 5 to slide dislocated when the movable knife 5 is reset, so as to avoid the two from being damaged by hard interference. The wire-containing groove 51 is in an arc shape along the surface of the movable knife 5, and the inner edge surface of the wire-containing groove 51 is processed by smooth transition. This is conducive to ensuring that the surface line can slide smoothly along the inner edge of the wire-containing groove 51, and ensuring that the surface line can slide to the area closest to the first fixed knife 3 when the movable knife 5 is reset to form a shear line. Further, a chip-clearing air pipe 13 capable of blowing air is connected to the machine base 1, one end of which can be connected to an existing air pump to achieve blowing, and the other end of the chip-clearing air pipe 13 is arranged toward the outer end of the second fixed knife 6.

[0031] like Figure 6 As shown, the machine base 1 is provided with a stepper motor 7, an intermediate shaft 8 and a lower shaft 4 for driving the rotary hook to rotate. The intermediate shaft is rotatably connected to the machine base and is parallel to the stepper motor 7 and the lower shaft 4. The outer periphery of the lower shaft 4 is provided with a swing arm 9 fixedly connected to the moving knife. The outer periphery of the swing arm 9 is hinged to the outer periphery of one end of the intermediate shaft 8 through a crank 10. The output end of the stepper motor 7 is fixedly connected with a rocker arm 11. The rocker arm 11 is hinged to the outer periphery of the other end of the intermediate shaft 8 through a connecting rod 12. When the output end of the stepper motor 7 rotates, it can drive the swing arm 9 to move around the lower shaft 4. In this way, the stepper motor 7 is conducive to more accurately controlling the movement of the moving knife 5 by introducing a setting program, ensuring accurate movement, and thus making the anti-bird nest performance more stable.

[0032] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed 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 rotary hook (2) connected to the machine base (1) and a first fixed knife (3), the bird nest prevention mechanism comprising a movable knife (5) capable of reciprocating around the periphery of the rotary hook (2), characterized in that: The movable knife (5) is provided with a thread accommodating groove (51) capable of confining the surface thread inside by downward airflow. The machine base (1) is also fixedly connected to a second fixed knife (6) located opposite to the first fixed knife (3). The outer end of the second fixed knife (6) abuts against the surface of the movable knife (5) at the position of the thread accommodating groove (51) closest to the first fixed knife (3). When the movable knife (5) moves toward the first fixed knife (3) and forms a shear with the first fixed knife (3), the machine needle can face the thread accommodating groove (51) below.

2. The anti-bird nest mechanism of the sewing machine according to claim 1, characterized in that: The outer end of the second fixed knife (6) is arranged to be inclined upward.

3. The anti-bird nest mechanism of the sewing machine according to claim 2, characterized in that: A clearance groove (61) is formed on the outer end of the second fixed knife (6) on the side facing the rotary shuttle (2).

4. The anti-bird nest mechanism of a sewing machine according to claim 1, 2 or 3, characterized in that: The second fixed knife (6) and the first fixed knife (3) are staggeredly distributed along the axial direction of the rotary hook (2); the side edge of the movable knife (5) close to the first fixed knife (3) has a cutting groove (52) arranged in a strip shape along the circumferential direction and the edge of which can form a shearing relationship with the first fixed knife (3); the edge of the wire accommodating groove (51) closest to the first fixed knife (3) is opposite to the middle section of the cutting groove (52) along the axial direction of the rotary hook (2).

5. The anti-bird nest mechanism of the sewing machine according to claim 1, 2 or 3, characterized in that: The side of the movable knife (5) away from the first fixed knife (3) has a chamfered surface (53), and the chamfered surface (53) is engaged with the inner edge surface of the wire accommodating groove (51).

6. The anti-bird nest mechanism of the sewing machine according to claim 4, characterized in that: The wire accommodating groove (51) is in an arc shape along the surface of the movable knife (5), and the inner edge surface of the wire accommodating groove (51) is processed by smooth transition.

7. The anti-bird nest mechanism of a sewing machine according to claim 1, 2 or 3, characterized in that: The machine base (1) is provided with a stepper motor (7), an intermediate shaft (8) and a lower shaft (4) for driving the rotary shuttle to rotate. The intermediate shaft (8) is rotatably connected to the machine base (1) and is parallel to the stepper motor (7) and the lower shaft (4). The outer periphery of the lower shaft (4) is sleeved with a swing arm (9) fixedly connected to the movable knife. The outer periphery of the swing arm (9) is hinged to the outer periphery of one end of the intermediate shaft (8) through a crank rod (10). The output end of the stepper motor (7) is fixedly connected with a swing arm (11). The swing arm (11) is hinged to the outer periphery of the other end of the intermediate shaft (8) through a connecting rod (12). When the output end of the stepper motor (7) rotates, it can drive the swing arm (9) to move around the lower shaft (4).

8. The anti-bird nest mechanism of a sewing machine according to claim 1, 2 or 3, characterized in that: A chip-clearing air pipe (13) capable of blowing or sucking air is provided in the machine base (1), and the end of the chip-clearing air pipe (13) is arranged toward the outer end of the second fixed knife (6).

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