Thread trimming structure of sewing machine

Abstract

The utility model provides a kind of thread trimming structure of sewing machine, belong to sewing machine technical field.It solves the problem of poor stability of existing thread trimming structure.The present sewing machine includes bottom plate, thread trimming structure includes drive source and fixed knife in the fixed connection in bottom plate, rotatable drive shaft that is arranged in bottom plate, second crank and third crank that are fixedly connected on the output shaft of drive source in the fixed connection in drive shaft other end, the one end of drive shaft is fixedly connected with first crank, and there is matched with the moving knife of fixed knife on first crank, the outer end of second crank is movably connected with third crank, and there is tension spring between the one end of second crank and bottom plate, the other end of second crank is fixedly connected with limit rod, and there is buffer pad in bottom plate, limit rod can be abutted on buffer pad under the action of tension spring tension, and drive shaft drives third crank rotation can overcome the tension of tension spring to make second crank rotate and drive drive shaft rotation.Thread trimming structure of the present sewing machine has the advantage of high stability.

Description

Technical Field

[0001] This utility model belongs to the field of sewing machine technology and relates to a thread-cutting structure for a sewing machine. Background Technology

[0002] A sewing machine is a mechanical device that uses one or more sewing threads to create specific stitches on a material (such as fabric, leather, etc.), allowing one or more layers of material to interweave or sew together. A sewing machine includes a thread-cutting mechanism to cut the sewing thread.

[0003] Existing sewing machine thread-cutting structures, such as the thread-cutting, presser foot lifting, and needle-distance adjusting device disclosed in Chinese patent literature [Patent No.: 201910098254.4; Application Publication No.: CN111501216B], include a power component, a first cam with a thread-cutting profile surface, a second cam with a presser foot lifting profile surface and a needle-distance adjusting profile surface, a thread-cutting drive crank connected to the thread-cutting mechanism, a presser foot lifting drive crank connected to the presser foot lifting mechanism, and a needle-distance adjusting drive crank connected to the needle-distance adjusting mechanism. The thread-cutting drive crank is provided with a thread-cutting ball that mates with the thread-cutting profile surface, the presser foot lifting drive crank is provided with a presser foot lifting ball that mates with the presser foot lifting profile surface, and the needle-distance adjusting drive crank is provided with a needle-distance adjusting ball that mates with the needle-distance adjusting profile surface.

[0004] In this type of sewing machine, the power component drives the first cam to rotate, and the thread-cutting profile surface of the first cam rotates around the axis of the power component's rotation shaft. The thread-cutting profile surface, acting on the thread-cutting ball bearings, drives the thread-cutting drive crank to swing. The swinging of the thread-cutting drive crank then moves the thread-cutting mechanism to perform the thread-cutting action. However, after thread cutting, the power component drives the first cam to rotate in the opposite direction and position it, causing the thread-cutting mechanism to rotate in the opposite direction and position itself, returning the moving blade to its initial position. During operation, the sewing machine experiences vibration, and the thread-cutting ball bearings move relative to the first cam, thus altering the initial position of the thread-cutting mechanism and reducing its stability. Summary of the Invention

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a thread-cutting structure for a sewing machine, thereby solving the technical problem of how to improve the stability of the thread-cutting structure.

[0006] The objective of this utility model can be achieved through the following technical solution: a thread-cutting structure for a sewing machine, the sewing machine including a base plate, the thread-cutting structure including a drive source and a fixed blade fixedly connected to the base plate, and a drive shaft rotatably passing through the base plate, one end of the drive shaft being fixedly connected to a first crank, the first crank being connected to a moving blade that cooperates with the fixed blade, characterized in that the thread-cutting structure further includes a second crank fixedly connected to the other end of the drive shaft and a third crank fixedly connected to the output shaft of the drive source, one end of the second crank being movably connected to the outer end of the third crank, a tension spring being provided between one end of the second crank and the base plate, a limit rod being fixedly connected to the other end of the second crank, a buffer pad being fixedly connected in the base plate, the limit rod being able to abut against the buffer pad under the action of the tension spring, the drive shaft driving the third crank to rotate can overcome the tension of the tension spring to make the second crank rotate and drive the drive shaft to rotate.

[0007] In the initial state, the limiting rod rests against the buffer pad under the tension of the spring, positioning the moving blade, drive shaft, first crank, and second crank. This prevents the position from changing due to vibrations during sewing machine operation, improving the stability of the thread-cutting structure and ensuring the moving blade remains in its initial position. During thread cutting, the drive shaft drives the third crank to rotate. One end of the second crank is movably connected to the outer end of the third crank, allowing the rotation of the third crank to drive the second crank to rotate, causing the limiting rod to move away from the buffer pad. This causes the drive shaft to rotate, which in turn drives the moving blade to rotate via the first crank, allowing the moving blade to engage with the fixed blade to cut the thread. After thread cutting is complete, the output shaft of the drive source rotates in the opposite direction, and the tension of the spring causes the limiting rod to rest against the buffer pad again, returning the moving blade to its initial state.

[0008] In the thread-cutting structure of the sewing machine described above, the second crank is bent, and the other end of the drive shaft is fixedly connected to the bent part of the second crank. One end of the second crank is perpendicular to the drive shaft, and the other end of the second crank is parallel to the drive shaft. This structure makes efficient use of space, allowing the second crank to be movably connected to the third crank in the narrow space below the base plate while simultaneously allowing the limiting rod to contact the buffer pad.

[0009] In the thread-cutting structure of the sewing machine described above, the third crank is elongated, and its outer end has an elongated sliding groove. One end of the second crank is equipped with a roller, which is embedded in the sliding groove and can move relative to the groove wall, thus movably connecting the second and third cranks. This structure simplifies the movable connection between the second and third cranks and ensures smooth rotation of both.

[0010] In the thread-cutting structure of the sewing machine described above, a pull plate is fixedly connected to the base plate, one end of the second crank has a protruding flange, one end of the tension spring is connected to the pull plate, and the other end of the tension spring is connected to the flange. This structure ensures that the tension spring is positioned appropriately, guaranteeing that the limiting rod can abut against the buffer pad under the tension of the tension spring.

[0011] In the thread-cutting structure of the sewing machine described above, the limiting rod is a bolt, which passes through the other end of the second crank and is locked by a nut. This structure allows the position of the limiting rod to be adjusted, enabling fine-tuning of the initial position of the moving blade and improving the positional accuracy of the moving blade.

[0012] In another scenario, in the thread-cutting structure of the sewing machine described above, the limiting rod is a pin, which passes through the other end of the second crank and is fixedly connected to it by a tight fit.

[0013] In the thread-cutting structure of the sewing machine described above, the sewing machine further includes a main shaft passing through the base plate. The main shaft is parallel to the drive shaft. The thread-cutting structure also includes a fourth crank and an annular blade holder sleeved on the main shaft. One end of the fourth crank is hinged to the first crank, and the other end of the fourth crank is hinged to the blade holder. The moving blade is fixed to the blade holder. Rotation of the first crank can drive the blade holder to rotate around the main shaft through the fourth crank.

[0014] In the thread-cutting structure of the sewing machine described above, the drive source is a motor, which has a pair of mounting plates. A pair of U-shaped mounting seats are fixedly connected to the base plate. The pair of mounting plates are respectively fixed to the pair of mounting seats, thus fixing the drive source in the base plate. The main shaft passes through the pair of mounting seats. This structure improves the firmness of the drive source fixation, thereby improving the stability of the thread-cutting structure. Furthermore, the U-shaped mounting seats prevent interference between the drive source installation and the main shaft installation, resulting in a reasonable arrangement.

[0015] Compared with the prior art, the thread-cutting structure for a sewing machine provided by this utility model has the following advantages:

[0016] 1. The limiting rod of this thread-cutting structure abuts against the buffer pad under the action of the tension spring, positioning the moving blade, drive shaft, first crank and second crank, preventing them from changing position due to vibration during sewing machine operation, thus improving the stability of the thread-cutting structure and ensuring that the moving blade is in the initial position.

[0017] 2. The second crank of this shearing structure is bent, making reasonable use of space. This allows the second crank to be movably connected to the third crank in the narrow space below the base plate, while also allowing the limiting rod to contact the buffer pad. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the location of the shearing structure.

[0019] Figure 2 This is a shearing structure Figure 1 A magnified view of region A in the middle.

[0020] Figure 3 This is a schematic diagram of the overall structure of this shearing structure.

[0021] Figure 4 This is a partial structural diagram of the shear wire structure.

[0022] In the diagram, 1 is the base plate; 2 is the drive source; 3 is the drive shaft; 4 is the first crank; 5 is the moving tool; 6 is the second crank; 61 is the flange; 7 is the third crank; 71 is the sliding groove; 8 is the tension spring; 9 is the limit rod; 10 is the buffer pad; 11 is the roller; 12 is the pull plate; 13 is the spindle; 14 is the fourth crank; 15 is the tool holder; 16 is the mounting plate; and 17 is the mounting base. Detailed Implementation

[0023] 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.

[0024] like Figure 1 , Figure 2 , Figure 3 As shown, the sewing machine includes a base plate 1, a main shaft 13, and a thread-cutting structure. The thread-cutting structure includes a drive source 2, a fixed blade, a drive shaft 3, a first crank 4, a moving blade 5, a second crank 6, a third crank 7, a tension spring 8, a limit rod 9, a buffer pad 10, a roller 11, a pull plate 12, a fourth crank 14, a blade holder 15, a mounting plate 16, and a mounting base 17.

[0025] The spindle 13 is mounted in the base plate 1. The drive source 2 is a motor with a pair of mounting plates 16. A pair of U-shaped mounting seats 17 are fixed in the base plate 1. The pair of mounting plates 16 are fixed to the pair of mounting seats 17 respectively, so that the drive source 2 is fixed in the base plate 1. The spindle 13 passes through the pair of mounting seats 17.

[0026] The drive shaft 3 is rotatably inserted into the base plate 1. The drive shaft 3 is parallel to the main shaft 13. The tool holder 15 is annular and is sleeved on the main shaft 13. The moving tool 5 is fixedly connected to the tool holder 15, and the fixed tool is fixedly connected to the base plate 1. The moving tool 5 and the fixed tool cooperate with each other. The fixed tool is not shown in the figure.

[0027] One end of the drive shaft 3 is fixedly connected to a first crank 4, one end of a fourth crank 14 is hinged to the first crank 4, and the other end of the fourth crank 14 is hinged to a tool holder 15. The other end of the drive shaft 3 is fixedly connected to a second crank 6, which is bent. The other end of the drive shaft 3 is fixedly connected to the bend of the second crank 6. One end of the second crank 6 is perpendicular to the drive shaft 3, and the other end of the second crank 6 is parallel to the drive shaft 3.

[0028] A third crank 7 is fixedly connected to the output shaft of drive source 2. The third crank 7 is elongated, as shown in the figure. Figure 4 As shown, the outer end of the third crank 7 has a long sliding groove 71, and one end of the second crank 6 is provided with a roller 11. The roller 11 is embedded in the sliding groove 71 and can move relative to each other along the groove wall of the sliding groove 71 so that the second crank 6 and the third crank 7 are movably connected.

[0029] The other end of the second crank 6 is fixedly connected to a limiting rod 9, and a buffer pad 10 is fixedly connected to the base plate 1. A tension spring 8 is provided between one end of the second crank 6 and the base plate 1. Specifically, a pull plate 12 is fixedly connected to the base plate 1, and one end of the second crank 6 has a protruding flange 61. One end of the tension spring 8 is connected to the pull plate 12, and the other end of the tension spring 8 is connected to the flange 61. The limiting rod 9 can abut against the buffer pad 10 under the tension of the tension spring 8.

[0030] In this embodiment, the limiting rod 9 is a bolt, which passes through the other end of the second crank 6 and is locked by a nut. In actual production, the limiting rod 9 is a pin, which passes through the other end of the second crank 6 and is fixedly connected by a tight fit.

[0031] Initially, the limiting rod 9 rests against the buffer pad 10 under the tension of the tension spring 8. During wire cutting, the drive shaft 3 drives the third crank 7 to rotate, overcoming the tension of the tension spring 8 to rotate the second crank 6 and drive the drive shaft 3 to rotate. The rotation of the drive shaft 3 causes the first crank 4 to rotate, and the rotation of the first crank 4 drives the blade 5 holder to rotate around the main shaft 13 via the fourth crank 14, thereby enabling the moving blade 5 and the fixed blade to cooperate and cut the wire. After the wire cutting is completed, the output shaft of the drive source 2 rotates in the opposite direction, and with the tension of the tension spring 8, the limiting rod 9 rests against the buffer pad 10 again, and the moving blade 5 returns to its initial state.

[0032] 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.

[0033] Although this document frequently uses terms such as base plate 1, drive source 2, drive shaft 3, first crank 4, moving tool 5, second crank 6, raised edge 61, third crank 7, sliding groove 71, tension spring 8, limit rod 9, buffer pad 10, roller 11, pull plate 12, main shaft 13, fourth crank 14, tool holder 15, mounting plate 16, and mounting base 17, the possibility of using other terms is not excluded. The use of these terms is merely for the convenience of describing and explaining the essence of this utility model; interpreting them as any additional limitation would contradict the spirit of this utility model.

Claims

1. A thread-cutting structure for a sewing machine, the sewing machine comprising a base plate (1), the thread-cutting structure comprising a drive source (2) and a fixed blade fixedly connected to the base plate (1), and a rotatable drive shaft (3) passing through the base plate (1), one end of the drive shaft (3) being fixedly connected to a first crank (4), and a movable blade (5) cooperating with the fixed blade being connected to the first crank (4), characterized in that, The wire-cutting structure also includes a second crank (6) fixed to the other end of the drive shaft (3) and a third crank (7) fixed to the output shaft of the drive source (2). One end of the second crank (6) is movably connected to the outer end of the third crank (7). A tension spring (8) is provided between one end of the second crank (6) and the base plate (1). A limit rod (9) is fixed to the other end of the second crank (6). A buffer pad (10) is fixed in the base plate (1). The limit rod (9) can abut against the buffer pad (10) under the action of the tension spring (8). The drive shaft (3) drives the third crank (7) to rotate, which can overcome the tension of the tension spring (8) to make the second crank (6) rotate and drive the drive shaft (3) to rotate.

2. The thread-cutting structure of a sewing machine according to claim 1, characterized in that, The second crank (6) is bent, and the other end of the drive shaft (3) is fixedly connected to the bend of the second crank (6). One end of the second crank (6) is perpendicular to the drive shaft (3), and the other end of the second crank (6) is parallel to the drive shaft (3).

3. The thread-cutting structure of a sewing machine according to claim 1, characterized in that, The third crank (7) is elongated, and the outer end of the third crank (7) has an elongated sliding groove (71). One end of the second crank (6) is provided with a roller (11). The roller (11) is embedded in the sliding groove (71) and the roller (11) can move relative to each other along the groove wall of the sliding groove (71) so that the second crank (6) and the third crank (7) are movably connected.

4. A thread-cutting structure for a sewing machine according to claim 1, 2, or 3, characterized in that, A pull plate (12) is fixedly connected to the base plate (1). One end of the second crank (6) has a protruding flange (61). One end of the tension spring (8) is connected to the pull plate (12), and the other end of the tension spring (8) is connected to the flange (61).

5. A thread-cutting structure for a sewing machine according to claim 1, 2, or 3, characterized in that, The limiting rod (9) is a bolt, which passes through the other end of the second crank (6) and is locked by a nut.

6. A thread-cutting structure for a sewing machine according to claim 1, 2, or 3, characterized in that, The limiting rod (9) is a pin, which passes through the other end of the second crank (6) and is fixedly connected to it by a tight fit.

7. A thread-cutting structure for a sewing machine according to claim 1, 2, or 3, characterized in that, The sewing machine also includes a main shaft (13) passing through the base plate (1), the main shaft (13) being parallel to the drive shaft (3), the thread cutting structure also including a fourth crank (14) and an annular blade holder (15) sleeved on the main shaft (13), one end of the fourth crank (14) being hinged to the first crank (4), the other end of the fourth crank (14) being hinged to the blade holder (15), the moving blade (5) being fixedly connected to the blade holder (15), the rotation of the first crank (4) can drive the blade holder (15) to rotate around the main shaft (13) through the fourth crank (14).

8. The thread-cutting structure of a sewing machine according to claim 7, characterized in that, The drive source (2) is a motor, which has a pair of mounting plates (16). A pair of U-shaped mounting seats (17) are fixed in the base plate (1). The pair of mounting plates (16) are fixed to the pair of mounting seats (17) respectively, so that the drive source (2) is fixed in the base plate (1). The main shaft (13) passes through the pair of mounting seats (17).

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