Thread trimming mechanism of sewing machine

Abstract

The invention provides a thread trimming mechanism of a sewing machine, and belongs to the technical field of sewing machines. A thread trimming mechanism of a sewing machine comprises a fixed cutter; the movable cutter assembly is matched with the fixed cutter, can translate relative to the fixed cutter and is used for trimming threads; the driving assembly is used for driving the moving cutter assembly to move back and forth, the driving assembly comprises a swing rod, the swing rod can swing around a first axis, one end of the swing rod is movably connected with the moving cutter assembly, and the swing rod is further provided with a contact assembly; a thread trimming cam is fixed to the transmission shaft and makes contact with the contact assembly, so that the swing rod can swing in the direction away from the fixed cutter; a push rod of the pusher is connected with the lower end of the contact assembly, and the pusher is used for enabling the swing rod to swing towards the fixed cutter.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewing machines, and particularly relates to a thread cutting mechanism of a sewing machine. Background Art

[0002] The thread cutting device built in the current zigzag sewing machine adopts a relatively complex multi-rod transmission structure: the thread cutting cam on the transmission shaft drives the moving knife assembly to reciprocate through multiple transmission rods to achieve thread cutting. However, due to the multi-rod structure, the overall structure of the device is complex, and there are many inconveniences in both assembly and maintenance, and the cost is relatively high. Summary of the Invention

[0003] The object of the present invention is to address the above problems existing in the prior art, and propose a thread cutting mechanism for a sewing machine, which has the characteristics of simple structure, stability and low cost.

[0004] The object of the present invention can be achieved by the following technical solutions:

[0005] A thread cutting mechanism for a sewing machine, comprising:

[0006] A fixed knife;

[0007] A moving knife assembly, which cooperates with the fixed knife and can translate relative to the fixed knife to achieve thread cutting;

[0008] A driving assembly, which is used to drive the moving knife assembly to move back and forth. The driving assembly includes:

[0009] A swing rod, which can swing around a first axis. One end of the swing rod is movably connected to the moving knife assembly, and a contact head assembly is also provided on the swing rod;

[0010] A rotatable transmission shaft, on which a thread cutting cam is fixed. The thread cutting cam contacts the contact head assembly so that the swing rod can swing away from the fixed knife;

[0011] A pusher, the push rod of which is connected to the lower end of the contact head assembly. The pusher is used to make the swing rod swing towards the fixed knife.

[0012] In the above thread cutting mechanism, a linear guide rail is further included. The moving knife assembly includes a moving knife body and a moving knife seat. The moving knife body is fixed on the moving knife seat, and the moving knife seat is fixed on the slider of the linear guide rail.

[0013] In the above thread cutting mechanism, a fixed knife seat is further included. A guide groove is provided on the fixed knife seat, and the moving knife body is slidably arranged in the guide groove and passes through the guide groove.

[0014] In the above-mentioned wire cutting mechanism, the fixed knife is detachably arranged on the fixed knife seat, and at least part of the fixed knife covers the guide groove to prevent the moving knife body from disengaging from the guide groove.

[0015] In the above-mentioned wire cutting mechanism, a limiting part is further arranged on the fixed knife seat, and the limiting part is used to limit the movement of the moving knife seat towards the fixed knife.

[0016] In the above-mentioned wire cutting mechanism, a guide hole is formed in the swing rod. The moving knife assembly further includes a connecting shaft and a guide block. The guide hole is arranged along the length direction of the swing rod. The guide block is rotatably assembled on the connecting shaft. The connecting shaft is installed on the moving knife seat. The guide block is arranged in the guide hole and can slide in the guide hole.

[0017] In the above-mentioned wire cutting mechanism, the pusher is specifically an electromagnetic pusher or a telescopic cylinder.

[0018] In the above-mentioned wire cutting mechanism, the contact head assembly includes a rotating ring and a rod body. The rod body is arranged on the swing rod. The rotating ring is rotatably arranged on the rod body and contacts the wire cutting cam. A connecting block is arranged at the end of the push rod of the pusher. An activity hole is arranged on the connecting block. The lower end of the rod body is inserted into the activity hole, and the lower end of the rod body can translate in the activity hole.

[0019] In the above-mentioned wire cutting mechanism, the wire cutting cam has an acting surface. The acting surface is arranged around the transmission shaft. The acting surface contacts the contact head assembly. The acting surface has a plurality of first abutting surfaces and second abutting surfaces arranged in a ring shape. The two ends of the first abutting surface are connected to the two ends of the second abutting surface through two transition surfaces. The first abutting surface is closer to the pusher than the second abutting surface.

[0020] Compared with the prior art, the present application has the following advantages:

[0021] Only three parts, namely the swing rod, the wire cutting cam and the pusher, are used to achieve reciprocating motion, without cascading multiple transmission rods. There are fewer components, the structure is more stable. After the parts are reduced, the assembly steps are simple, and it is more convenient to troubleshoot and replace parts. The wire cutting cam-swing rod structure reduces the transmission error and wear points, and improves the reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a three-dimensional structure diagram in the present application;

[0023] Figure 2 is a partial enlarged structure diagram in the present application;

[0024] Figure 3 is a partial enlarged structure diagram from another perspective in the present application;

[0025] Figure 4 It is a three-dimensional structure diagram of the position of the swing rod in this application;

[0026] Figure 5 It is an exploded view of the position of the swing rod in this application;

[0027] Figure 6 It is an exploded view of the moving knife assembly in this application;

[0028] In the figure,

[0029] A-A, the first axis;

[0030] 2. Fixed knife;

[0031] 3. Moving knife assembly; 31. Moving knife body; 32. Moving knife seat; 33. Connecting shaft; 34. Guide block;

[0032] 4. Driving assembly; 41. Swing rod; 411. Guide hole; 42. Thread cutting cam; 421. Acting surface; 4211. First abutting surface; 4212. Second abutting surface; 4213. Transition surface; 43. Transmission shaft; 44. Pusher; 441. Connecting block; 442. Moving hole; 45. Contact head assembly; 451. Rotating ring; 452. Rod body;

[0033] 5. Fixed knife seat; 51. Guide groove; 52. Limiting part;

[0034] 6. Linear guide rail; 61. Slide block;

[0035] 7. First fixing component;

[0036] 8. Second fixing component. Specific embodiments

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] As Figures 1 to 6As shown in the figure, a thread cutting mechanism of a sewing machine includes: a fixed knife 2, a moving knife assembly 3, and a driving assembly 4. The moving knife assembly 3 cooperates with the fixed knife 2 and can translate relative to the fixed knife 2 to achieve thread cutting. The driving assembly 4 is used to drive the moving knife assembly 3 to move back and forth. The driving assembly 4 includes: a swing rod 41, a rotatable transmission shaft 43, and a pusher 44. The swing rod 41 can swing around the first axis A-A. One end of the swing rod 41 is movably connected to the moving knife assembly 3, and a contact component 45 is also provided on the swing rod 41. A thread cutting cam 42 is fixed on the transmission shaft 43. The thread cutting cam 42 contacts the contact component 45 so that the swing rod 41 can swing in a direction away from the fixed knife 2. The push rod of the pusher 44 is connected to the lower end of the contact component 45, and the pusher 44 is used to make the swing rod 41 swing in the direction of the fixed knife 2.

[0039] In this application, the transmission shaft 43 in the driving assembly 4 drives the thread cutting cam 42 fixed on it to rotate. As the thread cutting cam 42 rotates, the protruding part of the thread cutting cam 42 presses against the contact component 45 on the swing rod 41, prompting the swing rod 41 to swing around the first axis in a direction away from the fixed knife 2. One end of the swing rod 41 drives the moving knife assembly 3 in a linked manner, pushing the moving knife to translate relative to the fixed knife 2 to the cutting position to complete the thread cutting action. When the thread cutting cam 42 rotates to the concave part, the contact component 45 swings the swing rod 41 back in the direction of the fixed knife 2 under the push of the push rod of the pusher 44, and the moving knife assembly 3 is reset under the action of the pusher 44 to complete a complete reciprocating cycle of thread cutting.

[0040] Only three parts, namely the swing rod 41, the thread cutting cam 42, and the pusher 44, are used to achieve reciprocating motion. There is no need for cascading multiple transmission rods, with fewer components and a more stable structure. After the parts are reduced, the assembly steps are simple, and troubleshooting and component replacement are more convenient. The thread cutting cam 42 - swing rod 41 structure reduces transmission errors and wear points, improving reliability.

[0041] The relationship between the fixed knife 2 and the moving knife assembly 3 remains the same as the structure in the prior art. The moving knife assembly 3 translates relative to the fixed knife 2 to achieve cutting. This application mainly improves the driving assembly 4 for the moving knife assembly 3 to make its structure simpler.

[0042] As Figure 1 shown in the figure, in this application, the sewing machine has a driving motor, a transmission rod body, a bevel gear pair and other structures for driving the rotation of the transmission shaft 43 and cooperating with the stitch and the rotary hook assembly. The stitch and the rotary hook assembly are prior art.

[0043] When this mechanism is installed in the sewing machine, the relative positions between the fixed knife 2, the transmission shaft 43, the first axis of the swing rod 41, and the pusher 44 remain unchanged. The overall structure is to drive the movement of the moving knife assembly 3 through the driving assembly 4 to achieve thread cutting.

[0044] Thus, if Figure 1 As shown, it also includes a first fixing component 7 and a second fixing component 8 , the swing rod 41 is rotatably connected to the first fixing component 7 , and the pusher 44 is fixed to the second fixing component 8 .

[0045] Specifically, Figures 1 to 3 As shown, it also includes a linear guide rail 6, and the movable knife assembly 3 includes a movable knife body 31 and a movable knife seat 32. The movable knife body 31 is fixed on the movable knife seat 32, and the movable knife seat (32) is fixed on the slider 61 of the linear guide rail 6.

[0046] The movable knife seat 32 cooperates with the linear guide rail 6 to ensure that the movable knife assembly 3 moves smoothly during the thread cutting process without position deviation.

[0047] Specifically, Figure 6 As shown, it also includes a fixed knife seat 5 , on which a guide groove 51 is provided, and the movable knife body 31 is slidably disposed in the guide groove 51 and passes through the guide groove 51 .

[0048] The fixed knife seat 5 firmly installs the fixed knife 2, and the guide groove 51 provides a stable movement channel for the movable knife body 31. Here, since the movable knife has a relatively slender knife body, it is further limited by the guide groove 51, which effectively ensures that the position does not shift during the thread cutting process; the guide groove 51 is matched with the movable knife body 31 in size, which can accurately limit the movement trajectory of the movable knife. With the constraint of the guide groove 51, the vibration generated during shearing can be effectively suppressed, and the shearing accuracy can be improved. The fixed knife 2 and the movable knife body 31 are arranged up and down.

[0049] Specifically, Figures 1 to 3 as well as Figure 6 As shown, the fixed knife 2 is detachably arranged on the fixed knife seat 5 , and the fixed knife 2 at least partially covers the guide groove 51 to restrict the movable knife body 31 from leaving the guide groove 51 .

[0050] The fixed knife 2 covers the opening of the guide groove 51, which can effectively prevent the movable knife body 31 from being separated from the guide groove 51 due to vibration or reverse force, thereby improving the safety of the mechanism. Furthermore, the fixed knife 2 is in contact with the movable knife body 31, which effectively suppresses the vibration of the movable knife during movement. The fixed knife 2 is detachable and the tightness can be adjusted by screws, which not only ensures reliable fixation, but also can be easily disassembled and maintained when necessary. In the event that the movable knife body 31 is damaged, the fixed knife 2 can be directly removed and the movable knife body 31 can be replaced.

[0051] Specifically, Figure 6 As shown, a limiting portion 52 is further provided on the fixed knife seat 5 , and the limiting portion 52 is used to limit the movable knife seat 32 from moving toward the fixed knife 2 .

[0052] The limiting portion 52 is a limiting recess corresponding to the guide groove 51 on the fixed knife seat 5. The limiting recess is communicated with the guide groove 51. The limiting recess allows a part of the moving knife seat 32 to enter the limiting recess, but cannot pass through the limiting recess and enter the guide groove 51. In some special cases, it can prevent the moving knife seat 32 from driving the moving knife body 31 to move excessively.

[0053] Specifically, as Figure 5 shown, a guide hole 411 is formed in the swing rod 41. The moving knife assembly 3 further includes a connecting shaft 33 and a guide block 34. The guide hole 411 is arranged along the length direction of the swing rod 41. The guide block 34 is rotatably assembled on the connecting shaft 33. The connecting shaft 33 is installed on the moving knife seat 32. The guide block 34 is arranged in the guide hole 411 and can slide in the guide hole 411.

[0054] When the driving assembly 4 makes the swing rod 41 swing around the first axis, the moving knife assembly 3 is driven to translate. Since the moving knife assembly 3 is in a translational state while the swing rod 41 is moving in a circular motion, a moving knife seat 32 that can slide along the guide hole on the swing rod 41 is provided. Then, the connecting shaft 33 on the moving knife assembly 3 is inserted into the guide block 34 and can rotate relative to the guide block 34. When the swing rod 41 drives the moving knife assembly 3 to translate, the guide block 34 moves in the guide hole 411, thereby realizing the drive.

[0055] Both sides of the guide block 34 are in contact with the inside of the guide hole 411, and the guide block 34 can only move along the length direction of the swing rod 41 into the guide hole 411.

[0056] The connecting shaft 33 is rotatably connected or fixed to the moving knife seat 32. Two limiting blocks for limiting the swing rod 41 are arranged on the connecting shaft 33. The swing rod 41 is arranged between the two limiting blocks. The limiting blocks are used to reduce the occurrence of the swing rod 41 shifting in the up and down positions.

[0057] Specifically, the pusher 44 is specifically an electromagnetic pusher or a telescopic cylinder. The electromagnetic pusher is a common component on a sewing machine and will not be elaborated here in detail as it is common knowledge.

[0058] Specifically, as Figure 5 shown, the contact head assembly 45 includes a rotating ring 451 and a rod body 452. The rod body 452 is arranged on the swing rod 41. The rotating ring 451 is rotatably arranged on the rod body 452 and contacts the thread cutting cam 42. A connecting block 441 is arranged at the end of the push rod of the pusher 44. An activity hole 442 is arranged on the connecting block 441. The lower end of the rod body 452 is inserted into the activity hole 442, and the lower end of the rod body 452 can translate in the activity hole 442.

[0059] Further, the rod body 452 is rotatably arranged on or fixed to the swing rod 41. The rod body 452 passes through the swing rod 41. A rotating ring 451 is arranged at the upper end of the rod body 452. The lower end of the rod body 452 is inserted into the movable hole 442. The width of the movable hole 442 is close to the diameter of the rod body 452, while the length of the movable hole 442 is greater than the diameter of the rod body 452, enabling the rod body 452 to move in the length direction of the movable hole 442.

[0060] The rotating ring 451 can freely rotate around the rod body 452. The rotating ring 451 is in direct contact with the thread cutting cam 42. The cam motion is accurately transmitted to the swing rod 41 through the rod body 452, reducing the contact wear between the thread cutting cam 42 and the rod body 452 and increasing the service life. There is a movable hole 442 provided on the connecting block 441 at the end of the push rod of the pusher 44. During the pushing process, the rod body 452 can also translate within the movable hole 442, thereby overcoming the displacement deviation driven by the swing rod 41 during the circular motion.

[0061] Specifically, as Figure 2 and Figure 4 shown, the thread cutting cam 42 has a working surface 421. The working surface 421 is arranged around the transmission shaft 43. The working surface 421 is in contact with the contact component 45. The working surface 421 has a plurality of first abutting surfaces 4211 and second abutting surfaces 4212 arranged in a ring shape. The two ends of the first abutting surface 4211 are connected to the two ends of the second abutting surface 4212 through two transition surfaces 4213. The first abutting surface 4211 is closer to the pusher 44 than the second abutting surface 4212.

[0062] A transition surface 4213 is provided at the connection between the first abutting surface 4211 and the second abutting surface 4212, which can provide buffering when the cam slides from one plane to another, reducing impact and vibration and improving the smoothness of the action. The first abutting surface 4211 is closer to the pusher 44, which means that when the thread cutting cam 42 rotates to this position, it can drive the swing rod 41 to swing towards the pusher 44. When the second abutting surface 4212 is in contact with the contact component 45, the swing rod 41 is correspondingly swung back towards the fixed knife 2 through the pusher 44.

[0063] Further, the thread cutting cam 42 and the transmission shaft 43 are coaxially arranged.

[0064] It should be noted that all directional indications in the embodiments of the present invention, such as up, down, left, right, front, back..., are only used to explain the relative positional relationship and motion conditions between the components in a specific posture, as shown in the drawings. If this specific posture changes, then the directional indication also changes accordingly.

[0065] In addition, the descriptions involving "first", "second", etc. in the present invention are for descriptive purposes only, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. At the same time, the meaning of "and / or" appearing throughout the text is as follows: including three scenarios. Taking "A and / or B" as an example, it includes Scenario A, or Scenario B, or the scenario where both A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0066] The above components are all common standard components or components known to those skilled in the art. Their structures and principles can all be learned by those skilled in the art through technical manuals or by conventional experimental methods.

[0067] The specific embodiments described herein are merely illustrative of the present invention. Those skilled in the art to which the present invention pertains can make various modifications or supplements to the described specific embodiments or use similar ways to substitute them, but will not deviate from the present invention or exceed the scope defined by the appended claims.

Claims

1. A thread cutting mechanism for a sewing machine, characterized in that, Comprising: A fixed knife (2); A moving knife assembly (3), the moving knife assembly (3) cooperating with the fixed knife (2) and being capable of translating relative to the fixed knife (2) for wire cutting; A driving assembly (4), the driving assembly (4) being used to drive the moving knife assembly (3) to move back and forth, the driving assembly (4) comprising: A swing rod (41), the swing rod (41) being capable of swinging around a first axis, one end of the swing rod (41) being movably connected to the moving knife assembly (3), and a contact head assembly (45) being further provided on the swing rod (41); A rotatable transmission shaft (43), a wire cutting cam (42) being fixed on the transmission shaft (43), the wire cutting cam (42) contacting the contact head assembly (45) so that the swing rod (41) can swing in a direction away from the fixed knife (2); A pusher (44), the push rod of the pusher (44) being connected to the lower end of the contact head assembly (45), the pusher (44) being used to make the swing rod (41) swing in a direction towards the fixed knife (2).

2. The thread cutting mechanism of the sewing machine according to claim 1, characterized in that, It further includes a linear guide rail (6), the moving knife assembly (3) including a moving knife body (31) and a moving knife seat (32), the moving knife body (31) being fixed on the moving knife seat (32), and the moving knife seat (32) being fixed on the slider (61) of the linear guide rail (6).

3. The thread cutting mechanism of the sewing machine according to claim 2, characterized in that, It further includes a fixed knife seat (5), a guide groove (51) being provided on the fixed knife seat (5), the moving knife body (31) being slidably arranged in the guide groove (51) and passing through the guide groove (51).

4. The thread cutting mechanism of a sewing machine according to claim 3, characterized in that, The fixed knife (2) is detachably arranged on the fixed knife seat (5), at least part of the fixed knife (2) covering the guide groove (51) to limit the moving knife body (31) from disengaging from the guide groove (51).

5. The thread cutting mechanism of the sewing machine according to claim 3 or 4, characterized in that, A limiting part (52) is further provided on the fixed knife seat (5), the limiting part (52) being used to limit the moving knife seat (32) from moving in a direction towards the fixed knife (2).

6. The thread cutting mechanism of the sewing machine according to claim 2, characterized in that, A guiding hole (411) is formed in the swing rod (41), the moving knife assembly (3) further including a connecting shaft (33) and a guiding block (34), the guiding hole (411) being arranged along the length direction of the swing rod (41), the guiding block (34) being rotatably assembled on the connecting shaft (33), the connecting shaft (33) being installed on the moving knife seat (32), and the guiding block (34) being arranged in the guiding hole (411) and capable of sliding in the guiding hole (411).

7. The thread cutting mechanism of the sewing machine according to claim 1, characterized in that, The pusher (44) is specifically an electromagnetic pusher (44) or a telescopic cylinder.

8. The thread cutting mechanism of a sewing machine according to claim 1, wherein The contact head assembly (45) includes a rotating ring (451) and a rod body (452), the rod body (452) being arranged on the swing rod (41), the rotating ring (451) being rotatably arranged on the rod body (452) and contacting the wire cutting cam (42), a connecting block (441) being arranged at the end of the push rod of the pusher (44), a movable hole (442) being provided on the connecting block (441), the lower end of the rod body (452) being inserted into the movable hole (442), and the lower end of the rod body (452) being capable of translating in the movable hole (442).

9. The thread cutting mechanism of a sewing machine according to claim 1, characterized in that, The wire-cutting cam (42) has a working surface (421) which is arranged around a transmission shaft (43). The working surface (421) contacts the contact head assembly (45). The working surface (421) has a plurality of first abutting surfaces (4211) and second abutting surfaces (4212) arranged in a ring. The two ends of the first abutting surface (4211) are connected to the two ends of the second abutting surface (4212) through two transition surfaces (4213). The first abutting surface (4211) is closer to the pusher (44) than the second abutting surface (4212).

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