Thread trimming mechanism of sewing machine

Abstract

The utility model relates to the technical field of sewing machines, in particular to a thread trimming mechanism of a sewing machine. A movable knife is fixedly connected to a movable knife rest, the movable knife rest is rotatably arranged on a lower shaft in a sleeving mode, the movable knife rest is hinged to a connecting rod, the connecting rod is hinged to a crank, the crank is fixed to an output shaft, the output shaft is connected with a thread trimming driver, and the thread trimming driver outputs power to drive the output shaft to rotate. The rotating shuttle is provided with a thread hooking hook, the movable cutter is provided with a thread hooking part and a thread trimming part, the thread hooking hook is located on the outer side of the thread hooking part, and the thread trimming part is located behind the thread hooking part. The working efficiency is improved, the sewn stitch is attractive, and the sewing quality is improved.

Description

Technical Field

[0001] This application relates to the field of sewing machine technology, specifically proposing a thread-cutting mechanism for a sewing machine. Background Technology

[0002] Each time a sewing machine sews, excess thread from the first stitch remains on the fabric. As sewing continues, the remaining thread is repeatedly tangled in the fabric, forming what is known in the market as a messy "bird's nest" of thread. Preventing the formation of these "bird's nests" is a crucial aspect of improving sewing quality and a technical goal that the sewing industry constantly strives to achieve.

[0003] The utility model patent with authorization announcement number CN205046329U describes: a base plate and a housing fixed to the base plate, a needle on the housing, a lower shaft and a drive shaft rotatably connected inside the base plate, the lower shaft and the drive shaft being parallel, a wire cutting mechanism including a moving blade, a fixed blade and a disc-shaped moving blade holder, the moving blade holder being fixed to the end of the lower shaft, the moving blade being fixedly connected to the moving blade holder, the drive shaft being driven to rotate the moving blade holder, the fixed blade being slidably connected inside the base plate, and the cutting edge of the fixed blade being opposite to the cutting edge of the moving blade, the needle being able to extend into the base plate and be located between the moving blade and the fixed blade, and a transmission structure being provided between the moving blade holder and the fixed blade, which can drive the fixed blade to move and move towards the needle when the moving blade holder rotates to one side and the moving blade moves closer to the fixed blade. In fact, before cutting the thread, because the moving blade is far from the needle, it needs to rotate a considerable distance to contact the thread. Furthermore, the stationary blade also needs to move during this process; the relative movement of the moving and stationary blades is necessary to cut the thread. This design results in a positional deviation between the point where the moving and stationary blades engage and the needle, leading to a relatively long thread end after cutting, creating "bird's nest" patterns on the fabric. This is the common double-blade design on the market. The more prevalent single-blade design is similar in structure, but the problem stems from the thread-cutting point being far from the seam, resulting in a long thread end but insufficient cutting time. Summary of the Invention

[0004] This application addresses the problems caused by the aforementioned bird's nest by providing a thread-cutting mechanism for a sewing machine. The mechanism comprises an output shaft, a crank, a connecting rod, a moving blade holder, a moving blade, a fixed blade, and a thread-cutting driver. The moving blade is fixed to the moving blade holder, which is rotatably mounted on a lower shaft. The moving blade holder is hinged to a connecting rod, which is hinged to a crank. The crank is fixed to the output shaft, which is connected to the thread-cutting driver. The thread-cutting driver outputs power to rotate the output shaft. The rotary hook has a hook, and the moving blade has a hooking part and a cutting part. The hook is located outside the hooking part, and the cutting part is located behind the hooking part.

[0005] Furthermore, the moving blade is located on the upper part of the rotary hook, and the moving blade also has a thread guide section. The thread guide section and the hook section are used to introduce excess thread. The thread guide section is located in front of the hook section, and the thread cutting section is located on the rear side of the thread guide section. The thread cutting section is used to cut the excess thread when the moving blade is pushed towards the fixed blade.

[0006] Furthermore, the wire-cutting driver drives a crank via an output shaft, which in turn drives the moving blade holder to rotate. The rotating moving blade holder causes the wire-cutting part of the moving blade to move towards the fixed blade.

[0007] Furthermore, under the control of the control system, the thread-cutting mechanism needs to cut off the excess thread after the first stitch is sewn.

[0008] Furthermore, the power output by the wire-cutting driver indirectly causes the moving blade to move along the circumferential direction through the output shaft, so that the moving blade can move from the initial position to the wire-cutting position and then return from the wire-cutting position to the initial position.

[0009] Furthermore, the wire-cutting driver is a stepper motor.

[0010] Furthermore, the wire-cutting mechanism is located outside the rotary shuttle mechanism.

[0011] The advantages of the thread-cutting mechanism of the sewing machine provided by this utility model compared with the prior art are as follows: a thread-cutting part is set on the moving blade, and a fixed blade is set corresponding to the thread-cutting part. The hook on the rotary hook catches the excess thread; the excess thread is cut off when the moving blade rotates. The thread-cutting mechanism of this application cuts off the excess thread when sewing the first stitch. The thread cutting is convenient and quick, and completely eliminates the formation of bird nests from the thread ends. There is no need to manually clean the bird nests. This not only improves work efficiency, but also makes the sewn stitches beautiful and improves the sewing quality. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the thread-cutting mechanism of a sewing machine according to this application;

[0013] Figure 2 This is a schematic diagram of the rear view structure of the thread cutting mechanism of a sewing machine according to this application;

[0014] Figure 3 yes Figure 2 Enlarged view of point A in the middle;

[0015] Figure 4 The application is for a structural diagram of the moving blade of the thread-cutting mechanism of a sewing machine.

[0016] The specific features referred to by the numbers in the above figures are as follows:

[0017] 10. Wire cutting mechanism, 11. Output shaft, 12. Crank, 13. Connecting rod, 14. Moving blade holder, 15. Moving blade, 151. Wire hooking part, 152. Wire passing part, 153. Wire cutting part, 16.

[0018] Rotary shuttle mechanism 20, rotary shuttle 21, hook 211;

[0019] Needle 30. Detailed Implementation

[0020] The following is in conjunction with the appendix Figure 1-4 The preferred embodiments of this application are described in detail to make the advantages and features of this application more easily understood by those skilled in the art, thereby providing a clearer and more definite definition of the scope of protection of this application. These embodiments are only used to illustrate the present invention and are not intended to limit the present invention. In addition, the terms such as "upper," "lower," "left," "right," "middle," and "one" used in this specification are only for ease of description and are not intended to limit the scope of implementation of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of implementation of the present invention.

[0021] The sewing machine of this application includes a thread cutting mechanism 10, a rotary hook mechanism 20, a needle 30, and a control system, etc. The thread cutting mechanism 10 has an output shaft 11, a crank 12, a connecting rod 13, a moving blade holder 14, a moving blade 15, a fixed blade 16, and a thread cutting driver, etc.; the rotary hook mechanism 20 has a rotary hook 21 and a lower shaft, etc., and the thread cutting mechanism 10 is disposed outside the rotary hook mechanism 20.

[0022] The thread-cutting mechanism of a sewing machine according to this application is as follows: a movable blade 15 is fixedly connected to a movable blade holder 14, the movable blade holder 14 is rotatably sleeved on a lower shaft, the movable blade holder 14 is hinged to a connecting rod 13, the connecting rod 13 is hinged to a crank 12, the crank 12 is fixed to an output shaft 11, the output shaft 11 is connected to a thread-cutting driver, and the thread-cutting driver outputs power to drive the output shaft 11 to rotate.

[0023] When the sewing machine's pressure plate is lowered to begin sewing, the needle 30, carrying the top thread, passes through the fabric. After the top and bottom threads form a loop, the needle 30 rises, and the thread-cutting mechanism 10 begins to cut off the excess thread. Under the control of the control system, the thread-cutting mechanism 10 needs to cut off the excess thread after the first stitch to prevent the excess thread from creating bird's nests.

[0024] The aforementioned wire-cutting driver drives the crank 12 via the output shaft 11. The crank 12 drives the moving blade holder 14 to rotate, and the rotating moving blade holder 14 drives the wire-cutting part 153 of the moving blade 15 to move towards the fixed blade 16. The aforementioned moving blade 15 is located on the upper part of the rotary hook 21. The moving blade 15 has a hooking part 151, a thread-passing part 152, and a wire-cutting part 153. The thread-passing part 152 and the hooking part 151 are used to introduce excess thread. The thread-passing part 152 is located in front of the hooking part 151, and the wire-cutting part 153 is located behind the thread-passing part 152 and behind the hooking part 151. The wire-cutting part 153 is used to cut the excess thread when the moving blade 15 is pushed towards the fixed blade 16.

[0025] The rotary hook 21 has a hook 211 located on the outside of the hook section 151. Here, after the excess thread is caught by the hook 211 of the rotating rotary hook 21, it is then caught by the hook section 151 until the excess thread is hooked into the thread cutting section 153 inside the moving blade 15. The thread cutting mechanism 10 can then cut off the excess thread, thus enabling the sewing machine to cut off the excess thread before sewing the second stitch. This completely avoids the adverse consequences of bird nests caused by excess thread, eliminating the need for manual cleaning of bird nests. This not only improves work efficiency but also results in beautiful stitches and improved sewing quality.

[0026] The power output from the wire-cutting driver indirectly causes the moving blade 15 to move in the circumferential direction through the output shaft 11, enabling the moving blade 15 to move from the initial position to the wire-cutting position and back to the initial position. The wire-cutting driver here is a stepper motor.

[0027] After the remaining wire is cut off, the wire cutting driver starts to run in the opposite direction, so that the entire wire cutting mechanism 10 returns to the initial position.

[0028] The above description is only one of the preferred embodiments of this application and is not intended to limit the present invention, nor does it limit the scope of patent implementation of this application. Any equivalent structural or procedural transformations made using the shape, structure, and principle described in the specification and drawings of this application, or any direct or indirect application in other related technical fields; any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention are all included within the scope of patent protection of this application.

Claims

1. A thread trimming mechanism of a sewing machine, characterized by comprising: The cutting thread mechanism has an output shaft, a crank, a connecting rod, a moving cutter holder, a moving cutter, a fixed cutter and a thread cutting driver, the moving cutter is fixed on the moving cutter holder, the moving cutter holder is rotatably sleeved on the lower shaft, the moving cutter holder is hinged on the connecting rod, the connecting rod is hinged on the crank, the crank is fixed on the output shaft, the output shaft is connected with the thread cutting driver, the thread cutting driver outputs power to drive the output shaft to rotate; the rotating hook has a thread hooking part, the moving cutter has a thread hooking part and a thread cutting part, the thread hooking part is located outside the thread hooking part, and the thread cutting part is located behind the thread hooking part.

2. A thread trimming mechanism for a sewing machine according to claim 1, wherein The moving cutter is arranged on the upper part of the rotating hook, and the moving cutter further has a thread passing part, the thread passing part and the thread hooking part are used for introducing the excess thread, the thread passing part is arranged in front of the thread hooking part, the thread cutting part is located on the rear side of the thread passing part, and the thread cutting part is used for cutting the excess thread when the moving cutter is pushed to the fixed cutter.

3. The thread trimming mechanism of claim 1 wherein, The thread cutting driver drives the crank through the output shaft, the crank drives the moving cutter holder to rotate, and the rotating moving cutter holder drives the thread cutting part of the moving cutter to move close to the fixed cutter.

4. The thread trimming mechanism of claim 1 wherein, Under the control of the control system, the cutting thread mechanism needs to perform the action of cutting the excess thread after sewing the first needle.

5. The thread trimming mechanism of claim 1 wherein, The power output by the thread cutting driver indirectly causes the moving cutter to move in the circumferential direction through the output shaft, so that the moving cutter moves from the initial position to the thread cutting position and then returns to the initial position from the thread cutting position.

6. The thread trimming mechanism of claim 1 wherein, The thread cutting driver is a stepping motor.

7. The thread trimming mechanism of claim 1 wherein, The cutting thread mechanism is arranged outside the rotating hook mechanism.

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