Thread trimming mechanism for a sewing machine

Abstract

The application relates to the technical field of sewing machines, and a thread cutting mechanism of a sewing machine comprises a cutter holder, a fixed cutter, a movable cutter, a connecting shaft and a driving source, the connecting shaft is rotationally connected to the cutter holder, the rotation axis of the connecting shaft is vertical, the driving source is connected to the cutter holder, the driving source is used for driving the connecting shaft to rotate, the movable cutter is connected to the upper end of the connecting shaft, the fixed cutter is connected to the cutter holder, and the fixed cutter is matched with the movable cutter to realize thread cutting. The driving source works, drives the connecting shaft to rotate, drives the movable cutter to rotate, the sewing thread is driven by the movable cutter to approach the fixed cutter, the movable cutter and the fixed cutter abut against each other to realize thread cutting operation, the structure of the thread cutting mechanism is simplified, and the manufacturing cost of the thread cutting mechanism is reduced.

Description

Technical Field

[0001] This application relates to the technical field of sewing machines, and in particular to a thread-cutting mechanism for a sewing machine. Background Technology

[0002] A sewing machine is a machine that uses one or more sewing threads to form one or more stitches on fabric, so that one or more layers of fabric are interwoven or sewn together. With the development of society, existing sewing machines are equipped with automatic thread cutting mechanisms, making them more convenient to use. However, the thread cutting mechanisms of many sewing machines are quite complex, which not only increases manufacturing costs but also makes maintenance more troublesome.

[0003] Chinese patent (publication number: CN106894175A; publication date: 2017-06-27) discloses an automatic thread-cutting mechanism for a sewing machine, including a lower shaft, a thread-cutting drive cam fixed on the lower shaft, a moving blade assembly that can swing around the lower shaft and has at least one moving blade and a moving blade holder, a crank shaft, a thread-cutting drive assembly mounted on one end of the crank shaft, a thread-cutting crank fixed on the other end of the crank shaft, and a thread-cutting connecting rod. The thread-cutting drive assembly has a first extension arm, the end of which is connected to a roller. The two ends of the thread-cutting connecting rod are respectively hinged to the thread-cutting crank and the moving blade holder. The ratio of the distance L1 between the crank shaft and the hinge point of the thread-cutting crank and the thread-cutting connecting rod to the distance L2 between the lower shaft and the hinge point of the moving blade holder and the thread-cutting connecting rod is not less than 2.5. The transmission angle γ of the thread-cutting connecting rod to the moving blade holder is not less than 40°.

[0004] The automatic thread-cutting mechanism for sewing machines disclosed in the aforementioned patent documents has a complex structure, many parts, and high manufacturing costs. Utility Model Content

[0005] To simplify the thread-cutting mechanism and reduce manufacturing costs, this application provides a thread-cutting mechanism for a sewing machine.

[0006] The sewing machine thread-cutting mechanism provided in this application adopts the following technical solution: A sewing machine thread-cutting mechanism includes a blade holder, a fixed blade, a movable blade, a connecting shaft, and a drive source. The connecting shaft is rotatably connected to the blade holder, and the axis of rotation of the connecting shaft is vertical. The drive source is connected to the blade holder and is used to drive the connecting shaft to rotate. The movable blade is connected to the upper end of the connecting shaft, and the fixed blade is connected to the blade holder. The fixed blade and the movable blade cooperate to cut the thread.

[0007] By adopting the above technical solution, the drive source works, drives the connecting shaft to rotate, drives the moving blade to rotate, and the moving blade drives the sewing thread to approach the fixed blade. The moving blade and the fixed blade abut against each other to realize the thread cutting operation, which simplifies the structure of the thread cutting mechanism and reduces the manufacturing cost of the thread cutting mechanism.

[0008] Preferably, it further includes a first mounting base, which is coaxially connected to the upper end of the connecting shaft. The upper end of the first mounting base is provided with a first fixing hole, and the moving blade is provided with a first connecting hole. The first connecting hole is used for a bolt to pass through and be threadedly connected to the first fixing hole.

[0009] By adopting the above technical solution, the first mounting base is coaxially connected to the upper end of the connecting shaft. The moving knife is threadedly connected to the first fixing hole of the first mounting base by a bolt passing through the first connecting hole of the moving knife. This allows the moving knife to be stably installed on the connecting shaft, facilitating the installation and disassembly of the moving knife and improving the convenience of the device.

[0010] Preferably, the upper end of the first mounting base is connected to a first positioning post, and the moving blade is provided with a first positioning hole for the first positioning post to be inserted.

[0011] By adopting the above technical solution, the first positioning pin on the first mounting base is embedded in the first positioning hole of the moving blade, which helps to rotate the moving blade so that the first connecting hole is aligned with the first fixing hole, accurately positioning the installation position of the moving blade. Furthermore, the first positioning pin and the bolt cooperate to achieve circumferential fixation of the moving blade and the first mounting base, improving the installation accuracy and stability of the moving blade and the connecting shaft.

[0012] Preferably, it further includes a wire-cutting crank and a drive disk, the drive disk being rotatably connected to the tool holder, the rotation axis of the drive disk being horizontal, the drive source being a drive motor, the drive motor being used to drive the drive disk to rotate, the drive disk having a drive groove on one side along the rotation axis of the drive disk, the bottom of the drive groove being arc-shaped, the wire-cutting crank being connected to the lower end of the connecting shaft, one end of the wire-cutting crank being used to abut against the bottom of the drive groove.

[0013] By adopting the above technical solution, the drive motor drives the drive disk to rotate, and the wire cutting crank is connected to the connecting shaft and abuts against the bottom of the drive groove, thereby driving the wire cutting crank to reciprocate around the axis of the connecting shaft. This enables the moving blade to rotate close to the fixed blade to cut the wire and for the moving blade to return to its original position to wait for the next wire cutting, simplifying the structure of the wire cutting mechanism and reducing manufacturing costs.

[0014] Preferably, it also includes a magnetic block and an electromagnet, wherein the magnetic block is connected to the wire-cutting crank and the electromagnet is connected to the tool holder, and the electromagnet is used to repel the magnetic block so that the wire-cutting crank is pressed against the bottom of the drive groove.

[0015] By adopting the above technical solution, the electromagnet repels the magnetic block, causing the magnetic block to move away from the electromagnet, which in turn drives the wire-cutting crank to rotate around the connecting shaft axis. This keeps the wire-cutting crank pressed against the bottom of the drive groove, causing the end of the wire-cutting crank that is in contact with the bottom of the drive groove to rotate back and forth along the bottom of the drive groove around the connecting shaft axis. This drives the moving blade to rotate back and forth, so that after the wire is cut, it returns to its original position to wait for the next wire cutting.

[0016] Preferably, it also includes an abutment wheel, which is connected to the wire-cutting crank, and the outer wall of the abutment wheel is used to abut against the bottom of the drive groove.

[0017] By adopting the above technical solution, the abutment wheel is connected to the wire-cutting crank to abut against the bottom of the drive groove, which can reduce the friction between the wire-cutting crank and the drive groove, making the transmission smoother and improving the stability and reliability of the wire-cutting mechanism.

[0018] Preferably, it also includes a pressure plate, which is connected to the blade holder and is used to cooperate with the fixed blade to clamp the sewing thread after cutting.

[0019] By adopting the above technical solution, the pressure plate and the fixed blade work together to clamp the sewing thread after it has been cut, making it easier for subsequent workers to remove the sewing thread from between the pressure plate and the fixed blade and re-pass it through the needle hole of the sewing machine's processing needle, thus improving the convenience of the device.

[0020] Preferably, it also includes a second mounting base, which is connected to the tool holder. The second mounting base is provided with a second fixing hole, the pressure plate is provided with a third connecting hole, and the fixed tool is provided with a second connecting hole. The second connecting hole and the third connecting hole are used for bolts to pass through in sequence and then be threadedly connected to the second fixing hole.

[0021] By adopting the above technical solution, the fixed blade and the pressure plate are fixed to the second mounting base with bolts, ensuring a stable fit between the pressure plate and the fixed blade. This facilitates the installation and removal of the fixed blade and the pressure plate, improving the convenience of the device. Preferably, the second mounting base has a second positioning post at the end away from the tool holder, the pressure plate has a second positioning hole, the fixed tool has a positioning groove, and the positioning groove and the second positioning hole are used for the second positioning post to be inserted.

[0022] By adopting the above technical solution, the second positioning post on the second mounting base is embedded in the second positioning hole of the pressure plate and the positioning groove of the fixed knife. This helps to rotate the pressure plate or the fixed knife so that the third connecting hole or the second connecting hole is aligned with the second fixing hole, accurately positioning the installation position of the pressure plate and the fixed knife. Furthermore, the second positioning post and the bolt cooperate to achieve circumferential fixation of the fixed knife and the pressure plate and the second mounting base, improving the installation accuracy and stability of the fixed knife and the pressure plate and the knife holder.

[0023] Preferably, the moving blade has a groove on the side away from the rotation axis of the connecting shaft, the groove being located on the side of the moving blade closer to the fixed blade, and the groove being used for inserting sewing thread.

[0024] By adopting the above technical solution, the moving blade is provided with a groove for the sewing thread to be inserted, which reduces the possibility that the sewing thread will detach from the moving blade when the moving blade rotates and drives the sewing thread to approach the fixed blade. This facilitates the moving blade and the fixed blade to cooperate better to complete the thread cutting action and improves the reliability of the device.

[0025] In summary, this application includes at least one of the following beneficial technical effects: 1. The drive source works, driving the connecting shaft to rotate, which in turn drives the moving blade to rotate. The moving blade brings the sewing thread closer to the fixed blade, and the moving blade and the fixed blade abut against each other to achieve the thread cutting operation. This simplifies the structure of the thread cutting mechanism and reduces the manufacturing cost of the thread cutting mechanism. 2. The drive motor drives the drive disk to rotate. The wire cutting crank is connected to the connecting shaft and abuts against the bottom of the drive groove, so as to drive the wire cutting crank to rotate back and forth around the axis of the connecting shaft. This enables the moving blade to rotate close to the fixed blade to cut the wire and the moving blade to return to its original position to wait for the next wire cutting. This simplifies the structure of the wire cutting mechanism and reduces manufacturing costs. 3. The electromagnet repels the magnetic block, causing the magnetic block to move away from the electromagnet. This drives the wire-cutting crank to rotate around the connecting shaft axis, keeping the wire-cutting crank pressed against the bottom of the drive groove. The end of the wire-cutting crank that is in contact with the bottom of the drive groove rotates back and forth along the drive groove bottom around the connecting shaft axis, driving the moving blade to rotate back and forth. After the wire is cut, the blade returns to its original position to wait for the next wire cutting. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the thread-cutting mechanism of a sewing machine.

[0027] Figure 2 This is an exploded structural diagram of the tool holder, the second mounting base, and the wire cutting assembly.

[0028] Figure 3 This is a partial sectional view of the tool holder, the second mounting base, and the wire cutting assembly.

[0029] Figure 4 This is a structural diagram of the knife holder, the second mounting base, and the wire cutting assembly.

[0030] Explanation of reference numerals in the attached figures: 1. Sewing machine frame; 11. Base; 111. Mounting cavity; 112. Slide groove; 12. Sewing machine body; 13. Knife holder; 14. Cover plate; 15. Second mounting base; 151. Second fixing hole; 152. Second positioning post; 2. Wire cutting assembly; 21. Connecting shaft; 22. Moving blade; 221. First connecting hole; 222. First positioning hole; 223. Groove; 23. Fixed blade; 231. Fixing base; 2311. Second connecting hole; 2312. Positioning groove; 232. Auxiliary blade; 24. First mounting base; 241. First fixing hole; 242. First positioning post; 25. Wire cutting crank; 251. Opening groove; 252. First connecting part; 253. Second connecting part; 26. Abutting post; 261. Mounting groove; 262. Snap groove; 27. Abutting wheel; 28. Snap ring; 29. ​​Drive source; 291. Drive motor; 210. Drive disk; 2101. Drive groove; 211. Pressure plate; 2111. Mounting part; 21111. Third connecting hole; 21112. Second positioning hole; 2112. Spring part; 2113. Magnetic block; 2114. Electromagnet. Detailed Implementation

[0031] The present application will be further described in detail below with reference to the accompanying drawings.

[0032] Reference Figure 1 This application discloses a sewing machine thread-cutting mechanism including a sewing machine frame 1. The sewing machine frame 1 includes a sewing machine body 12, a base 11, a blade holder 13, and a cover plate 14. The sewing machine body 12 is fixedly connected to the upper end of the base 11. The side surface of the base 11 near the sewing machine body 12 has a mounting cavity 111, and the blade holder 13 is embedded in the mounting cavity 111. The cover plate 14 is connected to the base 11 and covers the opening of the mounting cavity 111. The side surface of the base 11 near the sewing machine body 12 has a sliding groove 112, which communicates with the mounting cavity 111. The cover plate 14 is slidably embedded in the mounting cavity 111, and the sliding direction of the cover plate 14 is parallel to the length direction of the base 11.

[0033] Reference Figure 1 and Figure 2A sewing machine thread-cutting mechanism further includes a thread-cutting assembly 2, which includes a connecting shaft 21, a first mounting base 24, and a moving blade 22. The connecting shaft 21 is coaxially rotatably connected to a blade holder 13, and the axis of rotation of the connecting shaft 21 is vertical. The lower end of the first mounting base 24 is coaxially fixedly connected to the upper end of the connecting shaft 21. One end of the moving blade 22, along its thickness direction, abuts against the upper end of the first mounting base 24. The upper end of the first mounting base 24 is provided with a first fixing hole 241, the axis of which is parallel to and does not coincide with the axis of the first mounting base 24. The moving blade 22 is provided with a first connecting hole 221, which is used for a bolt to pass through and be threaded into the first fixing hole 241. A first positioning post 242 is fixedly connected to the upper end of the first mounting base 24, the axis of which is parallel to and does not coincide with the axis of the first mounting base 24. The moving blade 22 is provided with a first positioning hole 222, and the first positioning post 242 is coaxially embedded in the first positioning hole 222, with the outer wall of the first positioning post 242 fitting against the wall of the first positioning hole 222.

[0034] Reference Figure 2 and Figure 3 The wire cutting assembly 2 also includes a wire cutting crank 25, an abutment post 26, an abutment wheel 27, and a retaining ring 28. The wire cutting crank 25 has an opening groove 251, the lower end of the connecting shaft 21 is embedded in the opening groove 251 and locked by screws. One side of the outer circumference of the wire cutting crank 25 has an outwardly protruding first connecting portion 252. One end of the abutment post 26 is fixedly connected to the first connecting portion 252. The outer circumference of the end of the abutment post 26 away from the first connecting portion 252 is provided with... There is an installation groove 261, which is annular. An abutment wheel 27 is embedded in the installation groove 261, and the inner wall of the abutment wheel 27 is in contact with the groove wall of the installation groove 261. One end of the abutment wheel 27 abuts against the groove wall of the installation groove 261 near the first connecting part 252. The bottom of the installation groove 261 is provided with a retaining groove 262, which is annular. A retaining spring 28 is embedded in the retaining groove 262 and abuts against the end of the abutment wheel 27 away from the first connecting part 252.

[0035] Reference Figure 3 and Figure 4 The wire cutting assembly 2 also includes a drive disk 210 and a drive source 29. The drive disk 210 is coaxially rotatably connected to the side of the blade holder 13 near the wire cutting crank 25. The rotation axis of the drive disk 210 is parallel to the length direction of the base 11. The drive source 29 includes a drive motor 291, which is connected to the blade holder 13 and is used to drive the drive disk 210 to rotate. In this embodiment, the housing of the drive motor 291 is fixedly connected to the blade holder 13, and the output shaft of the drive motor 291 is coaxially fixedly connected to one end of the drive disk 210 near the blade holder 13. The end of the drive disk 210 near the blade holder 13 is provided with a drive groove 2101. The bottom of the drive groove 2101 is arc-shaped, and the groove wall is used to abut against the outer wall of the abutment wheel 27.

[0036] Reference Figure 4 The wire cutting assembly 2 also includes a magnetic block 2113 and an electromagnet 2114. A second connecting part 253 is fixedly connected to the outer wall of the wire cutting crank 25 away from the first connecting part 252. The magnetic block 2113 is fixedly connected to the second connecting part 253 away from the wire cutting crank 25. The electromagnet 2114 is fixedly connected to the blade holder 13. The electromagnet 2114 is used to repel the magnetic block 2113 to drive the outer wall of the abutment wheel 27 to press against the bottom of the drive groove 2101.

[0037] Reference Figure 2 The sewing machine frame 1 also includes a second mounting base 15, which is fixedly connected to the upper end of the blade holder 13. The thread cutting assembly 2 also includes a pressure plate 211 and a fixed blade 23. The pressure plate 211 includes a mounting part 2111 and a spring part 2112. One side surface of the mounting part 2111 along the thickness direction abuts against the upper end of the second mounting base 15. The fixed blade 23 includes a fixed base 231 and an auxiliary blade 232. The fixed base 231 abuts against the side surface of the mounting part 2111 away from the second mounting base 15. One end of the auxiliary blade 232 is fixedly connected to the side of the fixed base 231 near the moving blade 22. The length direction of the auxiliary blade 232 is parallel to the width direction of the base 11. The auxiliary blade 232 is used to cooperate with the moving blade 22 to cut the thread. The moving blade 22 has a groove 223 on the side away from the first mounting base 24 and near the second mounting base 15. The groove 223 is used for inserting the sewing thread. One end of the spring piece 2112 is fixedly connected to the side wall of the mounting part 2111. The spring piece 2112 is located on the side of the auxiliary blade 232 near the first mounting base 24. The spring piece 2112 is used to cooperate with the auxiliary blade 232 to clamp the sewing thread after cutting. The upper end of the second mounting base 15 is provided with a second fixing hole 151, the mounting part 2111 is provided with a third connecting hole 21111, and the fixed blade 23 is provided with a second connecting hole 2311. The second connecting hole 2311 and the third connecting hole 21111 are used for bolts to pass through in sequence and be threadedly connected to the second fixing hole 151. The upper end of the second mounting base 15 is fixedly connected with a second positioning post 152. The mounting part 2111 is provided with a second positioning hole 21112. The second positioning post 152 is embedded in the second positioning hole 21112, and the side wall of the second positioning post 152 fits against the wall of the second positioning hole 21112. The side wall of the fixed base 231 away from the auxiliary blade 232 is provided with a positioning groove 2312, and the second positioning post 152 is embedded in the positioning groove 2312. The side wall of the second positioning post 152 is in contact with the groove wall of the positioning groove 2312.

[0038] The implementation principle of a thread-cutting mechanism for a sewing machine according to an embodiment of this application is as follows: The drive motor 291 operates, causing the moving blade 22 to drive the drive disc 210 to rotate. The electromagnet 2114 drives the magnetic block 2113 away from the electromagnet 2114, causing the thread-cutting crank 25 to rotate. This causes the outer wall of the abutment wheel 27 to abut against the bottom of the drive groove 2101. The bottom of the drive groove 2101 pushes the abutment wheel 27 to rotate along the axis of the connecting shaft 21, causing the connecting shaft 21 to rotate, which in turn causes the first mounting base 24 to rotate, thus rotating the moving blade 22. The sewing thread is embedded in the groove 223, and the moving blade 22 moves the sewing thread closer to the auxiliary blade 232. The moving blade 22 abuts against the auxiliary blade 232, thus cutting the thread. As the drive disc 210 rotates, the moving blade 22 returns to its original position to await the next thread cut.

[0039] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A thread-cutting mechanism for a sewing machine, characterized in that: It includes a tool holder (13), a fixed blade (23), a movable blade (22), a connecting shaft (21), and a drive source (29); the connecting shaft (21) is rotatably connected to the tool holder (13); the axis of rotation of the connecting shaft (21) is vertical; the drive source (29) is connected to the tool holder (13); the drive source (29) is used to drive the connecting shaft (21) to rotate; the movable blade (22) is connected to the upper end of the connecting shaft (21); the fixed blade (23) is connected to the tool holder (13); the fixed blade (23) cooperates with the movable blade (22) to achieve wire cutting.

2. The sewing machine thread-cutting mechanism according to claim 1, characterized in that: It also includes a first mounting base (24); the first mounting base (24) is coaxially connected to the upper end of the connecting shaft (21); the upper end of the first mounting base (24) is provided with a first fixing hole (241); the moving knife (22) is provided with a first connecting hole (221); the first connecting hole (221) is used for the bolt to pass through and be threadedly connected to the first fixing hole (241).

3. The sewing machine thread-cutting mechanism according to claim 2, characterized in that: The first mounting base (24) is connected to the upper end of the first positioning post (242); the moving blade (22) is provided with a first positioning hole (222); the first positioning hole (222) is used for the first positioning post (242) to be inserted.

4. The sewing machine thread-cutting mechanism according to claim 1, characterized in that: It also includes a wire-cutting crank (25) and a drive disk (210); the drive disk (210) is rotatably connected to the tool holder (13); the rotation axis of the drive disk (210) is horizontal; the drive source (29) is a drive motor (291); the drive motor (291) is used to drive the drive disk (210) to rotate; the drive disk (210) has a drive groove (2101) on one side along the rotation axis of the drive disk (210); the bottom of the drive groove (2101) is arc-shaped; the wire-cutting crank (25) is connected to the lower end of the connecting shaft (21); one end of the wire-cutting crank (25) is used to abut against the bottom of the drive groove (2101).

5. The sewing machine thread-cutting mechanism according to claim 4, characterized in that: It also includes a magnetic block (2113) and an electromagnet (2114); the magnetic block (2113) is connected to the wire cutting crank (25); the electromagnet (2114) is connected to the tool holder (13); the electromagnet (2114) is used to repel the magnetic block (2113) so that the wire cutting crank (25) is pressed against the bottom of the drive groove (2101).

6. The sewing machine thread-cutting mechanism according to claim 4, characterized in that: It also includes an abutment wheel (27); the abutment wheel (27) is connected to the wire-cutting crank (25); the outer wall of the abutment wheel (27) is used to abut against the bottom of the drive groove (2101).

7. The sewing machine thread-cutting mechanism according to claim 1, characterized in that: It also includes a pressure plate (211); the pressure plate (211) is connected to the knife holder (13); the pressure plate (211) is used to cooperate with the fixed knife (23) to clamp the sewing thread after cutting.

8. The sewing machine thread-cutting mechanism according to claim 7, characterized in that: It also includes a second mounting base (15); the second mounting base (15) is connected to the tool holder (13); the second mounting base (15) is provided with a second fixing hole (151); the pressure plate (211) is provided with a third connecting hole (21111); the fixed tool (23) is provided with a second connecting hole (2311); the second connecting hole (2311) and the third connecting hole (21111) are used for bolts to pass through in sequence and then be threadedly connected to the second fixing hole (151).

9. The sewing machine thread-cutting mechanism according to claim 8, characterized in that: The second mounting base (15) is provided with a second positioning post (152) at one end away from the tool holder (13); the pressure plate (211) is provided with a second positioning hole (21112); the fixed tool (23) is provided with a positioning groove (2312); the positioning groove (2312) and the second positioning hole (21112) are used for the second positioning post (152) to be inserted.

10. The sewing machine thread-cutting mechanism according to claim 1, characterized in that: The moving blade (22) has a groove (223) on the side away from the rotation axis of the connecting shaft (21); the groove (223) is located on the side of the moving blade (22) close to the fixed blade (23); the groove (223) is used for inserting sewing thread.

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