Thread hooking and suction device for a sewing machine

Abstract

The present application belongs to the technical field of sewing machines, and relates to a thread catching and air suction device of a sewing machine, which comprises: a rotating hook arranged below a bottom plate of the sewing machine and driven by a lower shaft to rotate along a first circumferential direction about an axis thereof; a thread cutting assembly comprising a fixed blade and a movable blade, the fixed blade being fixed below the bottom plate, the movable blade being in an arc-shaped plate structure, the arc shape of the movable blade being arranged at a distance from and surrounding an outer periphery of the rotating hook, the movable blade being rotatable from a sewing position to a thread cutting position along a second circumferential direction; a thread catching assembly comprising an arc-shaped thread catching plate, the arc shape of the thread catching plate being arranged at a distance from and surrounding the outer periphery of the rotating hook, an end of the thread catching plate being provided with a thread catching hole, the thread catching plate being rotatable from the sewing position to a thread catching position along the second circumferential direction; and an air suction assembly comprising an air suction pipe connected with a negative pressure device. The thread catching and air suction device of the sewing machine provided by the present application can solve the bird nest problem of the sewing machine, and has excellent high-speed adaptability and high motion precision.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sewing machines, and relates to a thread hooking and air suction device of a sewing machine. BACKGROUND

[0002] In the sewing operation, especially in the initial stage of the sewing process, the "bird nest" phenomenon is a long-standing technical problem that seriously affects the quality of the sewn product and the production efficiency. The so-called "bird nest" refers to the fact that the sewing thread is wound and accumulated on the sewing material to form a disordered and irregular thread ball, which is similar in shape to a bird nest, hence the name. The main reason for its formation is that after the start of sewing, the thread tail on the side of the needle is often too long and is in a free state. When the sewing machine starts, the bobbin drives the bottom thread to rotate and interweave with the thread to form a stitch. In this process, the excessively long thread tail that has not been properly managed is easily rolled into the sewing area and wound and accumulated with the rotation of the bobbin, eventually forming a "bird nest". This not only makes the initial part of the sewn product have a messy stitch, affecting the appearance, but also seriously causes the sewing machine to jam, break the thread, and even stop, increasing the maintenance burden of the operator and reducing the production efficiency.

[0003] To overcome this problem, the common solution is to install an air suction device to suck away the residual thread tail at the beginning of sewing. For example, Chinese invention patent CN206873071U (publication date: January 12, 2018) discloses a sewing machine anti-bird nest device. The sewing machine includes a presser foot bottom plate and a presser foot handle, the presser foot handle is hingedly connected to the presser foot bottom plate, a blade is arranged between the presser foot bottom plate and the presser foot handle, one side of the presser foot handle has a thread hooking groove that penetrates through both ends, the anti-bird nest device includes an air cylinder, a thread hooking plate, and an air suction connector, the air cylinder is fixedly connected to the presser foot handle, one end of the thread hooking plate is fixedly connected to the piston rod of the air cylinder, the other end of the thread hooking plate has a thread hooking opening, the other end of the thread hooking plate can pass through the thread hooking groove and the thread hooking plate can move and abut against the groove wall of the thread hooking groove, and the air suction connector is fixedly connected to the side of the presser foot handle and seals the side of the thread hooking groove.

[0004] The deficiency of the above-mentioned sewing machine anti-bird nest device is that the core thread hooking component relies on the linear reciprocating motion of the air cylinder. This motion mode has large inertia and slow response at high speed, is prone to impact and wear, and is difficult to achieve precise and efficient synchronization with the high-speed rotating bobbin motion, thereby limiting the improvement of the overall speed of the sewing machine. SUMMARY

[0005] The present application provides a thread hooking and air suction device of a sewing machine to solve the bird nest problem of the sewing machine, while having excellent high-speed adaptability and high motion precision.

[0006] To solve the above technical problems, the purpose of the present application is achieved by the following technical solutions:

[0007] A thread catching and suction device of a sewing machine, comprising:

[0008] A rotating hook arranged below a bed of the sewing machine, driven by a lower shaft and rotating along a first circumferential direction around an axis of the rotating hook;

[0009] A thread cutting assembly comprising a fixed blade fixed below the bed and a movable blade in an arc shape, the arc shape of the movable blade being arranged around the outer periphery of the rotating hook with a distance from the outer periphery of the rotating hook, the movable blade being rotatable from a sewing position to a thread cutting position along a second circumferential direction;

[0010] A thread catching assembly comprising an arc-shaped thread catching plate, the arc shape of the thread catching plate being arranged around the outer periphery of the rotating hook with a distance from the outer periphery of the rotating hook, an end of the thread catching plate being provided with a thread catching hole, the thread catching plate being rotatable from a sewing position to a thread catching position along a second circumferential direction;

[0011] A suction assembly comprising a suction pipe connected with a negative pressure device;

[0012] When the thread catching plate is in the sewing position, the thread catching hole is located on a movement track of a needle, and the needle periodically passes through the thread catching hole during the sewing process; when the thread catching plate is rotated to the thread catching position, the thread catching hole is aligned with a pipe opening of the suction pipe to absorb the broken thread.

[0013] In the thread catching and suction device of the sewing machine, a front end of the lower shaft is sleeved with a shaft sleeve fixed on the bed, an annular movable blade holder and a thread catching holder are rotatably arranged on the shaft sleeve, the movable blade is assembled on the movable blade holder and rotates with the movable blade holder, and the thread catching plate is assembled on the thread catching holder and rotates with the thread catching holder.

[0014] In the thread catching and suction device of the sewing machine, a convex ring is arranged on the shaft sleeve, the convex ring is sequentially sleeved with the movable blade holder, a gasket and the thread catching holder from front to back, a pressing plate for axial limiting is fixed on the front end of the shaft sleeve, and the pressing plate is in abutment with the front end surface of the shaft sleeve and is fastened and connected with the shaft sleeve by a plurality of axial fasteners.

[0015] In the thread catching and suction device of the sewing machine, the movable blade and the thread catching plate are coaxially arranged with the rotating hook and rotate around the axis of the rotating hook; in a sewing state, the movable blade is located on a first circumferential side of the movement track of the needle, and the fixed blade and the thread catching plate are located on a second circumferential side of the movement track of the needle; in the sewing state, the body of the thread catching plate is located on the second circumferential side of the movement track of the needle, and the thread catching hole at the end of the thread catching plate can move to right below the needle, and the axis of the thread catching hole coincides with the axis of the needle.

[0016] In the thread catching and suction device of the sewing machine, the movable blade is driven by a stepping motor, the stepping motor is in transmission connection with the movable blade holder, the thread catching plate is driven by a pneumatic cylinder, the pneumatic cylinder is in transmission connection with the thread catching holder, and the stepping motor and the pneumatic cylinder can also be replaced by other power sources.

[0017] In the thread hooking and air suction device of the sewing machine, the step motor is fixed on the base plate, a thread cutting crank is sleeved on the motor shaft of the step motor, the thread cutting crank is hinged with a thread cutting driving shaft, a thread cutting driving crank is sleeved on the thread cutting driving shaft, one end of the thread cutting driving crank is hinged with a thread cutting connecting rod, and the other end of the thread cutting connecting rod is hinged with a movable knife holder.

[0018] In the thread hooking and air suction device of the sewing machine, a crank seat is fixed on the base plate, a rotating shaft is arranged through the crank seat, a cylinder connecting rod crank is sleeved on one end of the rotating shaft, and a thread hooking connecting rod crank is sleeved on the other end of the rotating shaft, the cylinder is arranged on the crank seat and is hinged with the cylinder connecting rod, the thread hooking connecting rod crank is hinged with a thread hooking frame through a thread hooking connecting rod.

[0019] In the thread hooking and air suction device of the sewing machine, an air suction fixing seat is fixed on the base plate, an air suction pipe is fixed on the air suction fixing seat through a pipe pressing plate and is arranged in a slanting manner towards the thread hooking plate, and an inclined surface matched with a thread hooking hole is arranged on the end surface of the air suction pipe.

[0020] Compared with the prior art, the thread hooking and air suction device of the sewing machine has the following beneficial effects:

[0021] 1. The thread hooking and air suction device of the sewing machine is provided, the thread hooking plate is designed as an arc shape and rotates around the periphery of the hook, the movement mode is the same as the rotation of the hook, the inertia is smaller, the response is faster, the perfect matching with high-speed sewing can be easily realized, the movement coordination is excellent, and the thread hooking positioning is more accurate and reliable.

[0022] 2. The thread hooking plate can realize more efficient cooperative work with the hook: in the thread hooking process, the hook rotates in a first direction first to pull the thread to be trimmed, then the thread hooking plate rotates in a second direction to hook the thread to a predetermined position for accurate thread cutting.

[0023] 3. The structure is more compact and has higher integration: the thread hooking, thread cutting (movable knife) and air suction functions are highly integrated on the outer periphery of the hook, forming a functional module with the hook as the core. The integrated design greatly saves space, makes the mechanism layout very compact, and is particularly suitable for the head design of modern sewing machines with limited space. In addition, the entire mechanism is integratedly installed through a small number of core components such as a shaft sleeve, a movable knife holder and a thread hooking frame, and the structure is simple and clear. The components are coaxially arranged, the transmission chain is short, the stability of the movement is ensured, and the installation, debugging and maintenance are more convenient.

[0024] 4、The present application hooks the surface thread through the hooking hole, has better stability in the hooking process, avoids the surface thread from separating, and can also accurately hook the surface thread to the position of the air suction pipe, so that the air suction port and the thread end capturing point realize "zero distance" docking. Once the hooking plate with the thread end turns to the position, the broken thread can be instantly and completely sucked away, fundamentally eliminating the bird nest problem caused by untimely air suction or poor air flow path. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 is a perspective view of the present application;

[0026] Figure 2 is an internal perspective view of the present application (sewing position);

[0027] Figure 3 is an internal perspective view of the present application (thread cutting position, thread hooking position);

[0028] Figure 4 is a transmission structure diagram of the present application;

[0029] Figure 5 is a driving structure diagram of the air cylinder of the present application;

[0030] Figure 6 is an installation structure diagram of the moving knife and the thread hooking plate of the present application;

[0031] Figure 1, rotating hook; 2, bottom plate; 3, lower shaft; 4, fixed knife; 5, moving knife; 6, thread hooking plate; 7, thread hooking hole; 8, air suction pipe; 9, needle; 10, shaft sleeve; 11, moving knife holder; 12, thread hooking holder; 13, protruding ring; 14, gasket; 15, pressing plate; 16, stepping motor; 17, air cylinder; 18, thread cutting crank; 19, thread cutting drive shaft; 20, thread cutting drive crank; 21, thread cutting connecting rod; 22, crank seat; 23, rotating shaft; 24, air cylinder connecting rod crank; 25, thread hooking connecting rod crank; 26, air cylinder connecting rod; 27, thread hooking connecting rod; 28, air suction fixing seat; 29, pipe pressing plate. DETAILED DESCRIPTION

[0032] The present application will be further described below with specific embodiments in conjunction with the accompanying drawings, referring to Figures 1-6 :

[0033] A thread hooking and air suction device of a sewing machine, comprising:

[0034] The rotating hook 1 is arranged below the bottom plate 2 of the sewing machine, is driven by the lower shaft 3 and rotates along the first circumferential direction around the axis thereof;

[0035] The cutting assembly comprises a fixed blade 4 fixed below the base plate 2 and a movable blade 5 in the shape of an arc, which is arranged around the outer periphery of the rotating hook 1 at a distance from the outer periphery of the rotating hook 1, and the movable blade 5 can rotate from the sewing position to the cutting position along the second circumferential direction;

[0036] The thread catching assembly comprises an arc-shaped thread catching plate 6, which is arranged around the outer periphery of the rotating hook 1 at a distance from the outer periphery of the rotating hook 1, and the end of the thread catching plate 6 is provided with a thread catching hole 7, and the thread catching plate 6 can rotate from the sewing position to the thread catching position along the second circumferential direction;

[0037] The air suction assembly comprises an air suction pipe 8 connected with the negative pressure device;

[0038] When the thread catching plate 6 is in the sewing position, the thread catching hole 7 is located on the movement track of the needle 9, and the needle 9 periodically passes through the thread catching hole 7 during the sewing process; when the thread catching plate 6 rotates to the thread catching position, the thread catching hole 7 is aligned with the pipe opening of the air suction pipe 8 to absorb the broken thread.

[0039] In the embodiment, the movable blade 5 and the thread catching plate 6 are coaxially arranged with the rotating hook 1 and rotate around the axis of the rotating hook 1; in the sewing state, the movable blade 5 is located on the first circumferential side of the movement track of the needle 9, and the fixed blade 4 and the thread catching plate 6 are located on the second circumferential side of the movement track of the needle 9; in the sewing state, the body of the thread catching plate 6 is located on the second circumferential side of the movement track of the needle 9, and the thread catching hole 7 at the end of the thread catching plate 6 can move to the position directly below the needle 9, and the axis of the thread catching hole 7 is coincident with the axis of the needle 9.

[0040] To the accompanying drawings Figure 1 , the accompanying drawings Figure 2 , and the accompanying drawings Figure 3 , the working process of the embodiment is as follows: the sewing machine is started, in the starting sewing stage, the lower shaft 3 drives the rotating hook 1 to rotate along the first circumferential direction, the rotating hook 1 hooks the thread introduced by the needle 9 and forms a thread loop; then, the thread catching plate 6 rotates from the sewing position to the thread catching position along the second circumferential direction, since the thread passes through the thread catching hole 7, the thread is pulled when the thread catching plate 6 rotates, when the thread catching plate 6 rotates to the thread catching position, the thread is pulled to the cutting position, and the thread catching hole 7 is aligned with the pipe opening of the air suction pipe 8; then, when the needle 9 moves to the upper dead point, the movable blade 5 rotates from the sewing position to the cutting position along the second circumferential direction, and cooperates with the fixed blade 4 to cut the thread; after the thread is cut, the thread end cut off is rapidly sucked into the air suction pipe 8 by the negative pressure formed by the negative pressure device; after the thread absorption is completed, the thread catching plate 6 and the movable blade 5 are reset to the sewing position, and normal sewing is performed.

[0041] To the accompanying drawings Figure 6In the embodiment, the specific mounting structure of the cutting thread assembly and the hooking thread assembly is that the front end of the lower shaft 3 is sleeved with a shaft sleeve 10 fixed on the bottom plate 2, an annular movable cutter holder 11 and a hooking thread holder 12 are rotationally arranged on the shaft sleeve 10, the movable cutter 5 is assembled on the movable cutter holder 11 and rotates with the movable cutter holder 11, and the hooking thread plate 6 is assembled on the hooking thread holder 12 and rotates with the hooking thread holder 12.

[0042] Further, the shaft sleeve 10 is provided with a convex ring 13, the convex ring 13 is sequentially sleeved with the movable cutter holder 11, a gasket 14 and the hooking thread holder 12 from front to back, the front end of the shaft sleeve 10 is fixed with a pressing plate 15 for axial limiting, and further, the pressing plate 15 is in abutment with the front end surface of the shaft sleeve 10 and is fastened and connected with the shaft sleeve 10 through a plurality of axial fasteners.

[0043] Through the above structure, the coaxial arrangement of the movable cutter 5 and the hooking thread plate 6 and the rotating shuttle 1 is realized, and the concentricity and stability of movement are ensured.

[0044] By comparing the drawings Figure 4 and the drawings Figure 5 , the driving structure of the embodiment is that the movable cutter 5 is driven by a stepping motor 16, the stepping motor 16 is in transmission connection with the movable cutter holder 11, the hooking thread plate 6 is driven by a gas cylinder 17, the gas cylinder 17 is in transmission connection with the hooking thread holder 12, and the stepping motor 16 and the gas cylinder 17 can also be replaced by other power sources.

[0045] Specifically, the driving structure of the movable cutter 5 is that the stepping motor 16 is fixed on the bottom plate 2, a thread cutting crank 18 is sleeved on the motor shaft of the stepping motor 16, the thread cutting crank 18 is hinged with a thread cutting driving shaft 19, a thread cutting driving crank 20 is sleeved on the thread cutting driving shaft 19, one end of the thread cutting driving crank 20 is hinged with the thread cutting driving shaft 19, and the other end of the thread cutting driving crank 20 is hinged with the movable cutter holder 11. The driving process of the movable cutter 5 is that the stepping motor 16 rotates according to a preset program, and through the transmission chain of the thread cutting crank 18, the thread cutting driving shaft 19, the thread cutting driving crank 20 and the thread cutting connecting rod 21, the rotary motion is converted into the limited angle rotation of the movable cutter holder 11, so as to accurately rotate the movable cutter 5 between the sewing position and the thread cutting position.

[0046] Specifically, the driving structure of the thread hooking plate 6 is that a crank base 22 is fixed on the bottom plate 2, a rotating shaft 23 is arranged through the crank base 22, a cylinder connecting rod crank 24 is sleeved on one end of the rotating shaft 23, and a thread hooking connecting rod crank 25 is sleeved on the other end of the rotating shaft 23, the cylinder 17 is installed on the crank base 22 and is hinged with the cylinder connecting rod crank 24 through a cylinder connecting rod 26, and the thread hooking connecting rod crank 25 is hinged with the thread hooking frame 12 through a thread hooking connecting rod 27. The driving process of the thread hooking plate 6 is that the piston rod of the cylinder 17 is extended or retracted, the cylinder connecting rod crank 24 is pushed through the cylinder connecting rod 26, the rotating shaft 23 is rotated, and then the thread hooking frame 12 and the thread hooking plate 6 are rotated between the sewing position and the thread hooking position through the thread hooking connecting rod crank 25 and the thread hooking connecting rod 27.

[0047] In the embodiment, the specific mounting structure of the air suction assembly is that an air suction fixing base 28 is fixed on the bottom plate 2, the air suction pipe 8 is fixed on the air suction fixing base 28 through a pipe pressing plate 29 and is arranged in an inclined manner towards the thread hooking plate 6, and an end surface of the air suction pipe 8 is provided with an inclined surface matched with the thread hooking hole 7.

[0048] The above embodiment is only a preferred embodiment of the present application, and does not limit the protection scope of the present application, so that: any equivalent change made according to the structure, shape, principle of the present application should be covered in the protection scope of the present application.

Claims

1. A thread-hooking suction device for a sewing machine, characterized in that, include: A rotary hook (1) is located below the base plate (2) of the sewing machine and is driven by the lower shaft (3) to rotate around its axis in the first circumferential direction; The thread-cutting assembly includes a fixed blade (4) and a movable blade (5). The fixed blade (4) is fixed below the base plate (2). The movable blade (5) is an arc-shaped piece structure. Its arc maintains a distance from the outer periphery of the rotary hook (1) and is arranged around the outer periphery of the rotary hook (1). The movable blade (5) can rotate from the sewing position to the thread-cutting position along the second circumferential direction. The hook assembly includes an arc-shaped hook plate (6), the arc of which is spaced from the outer periphery of the rotary hook (1) and is arranged around the outer periphery of the rotary hook (1). The end of the hook plate (6) is provided with a hook hole (7). The hook plate (6) can be rotated from the sewing position to the hook position along the second circumferential direction. The suction assembly includes a suction pipe (8) connected to a negative pressure device; When the hook plate (6) is in the sewing position, its hook hole (7) is located on the movement trajectory of the needle (9), and the needle (9) periodically passes through the hook hole (7) during the sewing process; when the hook plate (6) rotates to the hook position, the hook hole (7) is aligned with the opening of the suction pipe (8) to absorb broken thread.

2. The thread-hooking suction device for a sewing machine according to claim 1, characterized in that, The front end of the lower shaft (3) is fitted with a bushing (10) fixed on the base plate (2). A ring-shaped moving knife holder (11) and a hooking frame (12) are rotatably mounted on the bushing (10). The moving knife (5) is mounted on the moving knife holder (11) and rotates with it. The hooking plate (6) is mounted on the hooking frame (12) and rotates with it.

3. The thread-hooking suction device for a sewing machine according to claim 2, characterized in that, The bushing (10) is provided with a convex ring (13), and a moving tool holder (11), a gasket (14) and a hook frame (12) are sequentially fitted on the front side of the convex ring (13). The front end of the bushing (10) is fixed with a pressure plate (15) for axial positioning.

4. The thread-hooking suction device for a sewing machine according to claim 2, characterized in that, The moving blade (5) and the hook plate (6) are both coaxially arranged with the rotary hook (1) and rotate around the axis of the rotary hook (1); in the sewing state, the moving blade (5) is located on the first circumferential side of the movement trajectory of the needle (9), and the fixed blade (4) and the hook plate (6) are located on the second circumferential side of the movement trajectory of the needle (9).

5. A thread-hooking suction device for a sewing machine according to claim 2, characterized in that, The moving blade (5) is driven by a stepper motor (16), which is connected to the moving blade holder (11) in a transmission manner; the hook plate (6) is driven by a cylinder (17), which is connected to the hook frame (12) in a transmission manner.

6. The thread-hooking suction device for a sewing machine according to claim 5, characterized in that, The stepper motor (16) is fixed on the base plate (2), and a wire-cutting crank (18) is mounted on its motor shaft. The wire-cutting crank (18) is hinged to the wire-cutting drive shaft (19). A wire-cutting drive crank (20) is mounted on the wire-cutting drive shaft (19). The wire-cutting drive crank (20) is hinged to one end of the wire-cutting connecting rod (21), and the other end of the wire-cutting connecting rod (21) is hinged to the moving blade holder (11).

7. The thread-hooking suction device for a sewing machine according to claim 5, characterized in that, A crank seat (22) is fixed on the base plate (2). A rotating shaft (23) is passed through the crank seat (22). A cylinder connecting rod crank (24) is fitted at one end of the rotating shaft (23), and a hook connecting rod crank (25) is fitted at the other end. The cylinder (17) is installed on the crank seat (22) and is hinged to the cylinder connecting rod crank (24) through the cylinder connecting rod (26). The hook connecting rod crank (25) is hinged to the hook frame (12) through the hook connecting rod (27).

8. The thread-hooking suction device for a sewing machine according to claim 1, characterized in that, A suction mounting base (28) is fixed on the base plate (2). The suction pipe (8) is fixed on the suction mounting base (28) by the pressure plate (29) and is inclined towards the hook plate (6). The end face of the suction pipe (8) is provided with an inclined surface that cooperates with the hook hole (7).

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