A single-acting blade anti-bird nest wire-cutting mechanism and its control method

Abstract

This invention provides a single-action anti-bird nest thread-cutting mechanism and its control method. The single-action anti-bird nest thread-cutting mechanism includes a fixed blade, a rotatable movable blade, a thread-cutting drive source, and a thread-cutting drive assembly. The fixed blade has a fixed blade edge. The thread-cutting drive source is connected to the movable blade via the thread-cutting drive assembly, driving the movable blade to rotate towards or away from the fixed blade. The movable blade has a starting thread hook groove and a separating thread hook groove. The starting thread hook groove allows the sewing machine needle to pass through. The movable blade has a moving blade edge on its surface facing the fixed blade. The starting thread hook groove and the separating thread hook groove are distributed on the same side of the moving blade edge. This application uses the same thread-cutting drive source and the same set of movable and fixed blades to achieve the purpose of preventing bird nests during the starting thread cutting and automatic thread cutting after sewing, effectively avoiding thread breakage during the starting thread and achieving a stable effect of normal starting thread without bird nest clumps.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and in particular to a single-action knife anti-bird nest thread-cutting mechanism and its control method. Background Technology

[0002] A sewing machine is a machine that uses one or more sewing threads to create one or more stitches on fabric, allowing one or more layers of fabric to interweave or sew together. A sewing machine mainly consists of a base (i.e., the casing and base plate), a needle bar mechanism, a feeding mechanism, a thread hooking mechanism, a presser foot mechanism, a thread cutting mechanism, and accessories. Through the coordinated movement of these mechanisms, they work in a cyclical manner to sew the fabric together.

[0003] To improve sewing efficiency, sewing equipment typically employs automatic thread cutters, which not only ensure smooth sewing but also reduce thread ends in garments, improving subsequent finishing efficiency. However, existing thread cutters can only cut the thread after the sewing process is complete, not at the start of a second stitch. Therefore, during the second stitch, a certain length of thread remains on the needle, causing it to form a bird's nest pattern on the garment, affecting overall garment quality. To ensure garment quality, this thread must be manually trimmed, increasing labor intensity and impacting production efficiency.

[0004] In the prior art, some sewing machines are equipped with thread-cutting mechanisms that can capture the top thread at the start of a stitch. For example, the thread-cutting structure of a sewing machine disclosed in Chinese Utility Model Patent Application No. 201720787765.3 cuts the captured thread after the sewing machine has rotated to a certain angle, and performs the thread-cutting function again after sewing is completed. However, because the thread-cutting structure's starting point is located between the movable and fixed blade edges, the control system immediately controls the motor to drive the blade to cut the thread after the needle leaves the needle plate. This can easily lead to the top thread not being interlaced enough during the starting process, resulting in the thread coming undone. If the thread is not cut after the needle leaves the needle plate, subsequent sewing will be impossible. Summary of the Invention

[0005] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a single-action anti-bird nest thread-cutting mechanism that can be used for both thread cutting at the beginning of a stitch and thread cutting at the end of a stitch, and can effectively prevent thread from coming loose at the beginning of a stitch.

[0006] To achieve the above objectives, the present invention provides a single-acting blade anti-bird nest thread-cutting mechanism, comprising a fixed blade, a rotatable movable blade, a thread-cutting drive source, and a thread-cutting drive assembly. The fixed blade is provided with a fixed blade edge. The thread-cutting drive source is connected to the movable blade via the thread-cutting drive assembly, driving the movable blade to rotate towards or away from the fixed blade. The movable blade is provided with a starting thread hook groove and a separating thread hook groove. The starting thread hook groove allows the sewing machine needle to pass through. The movable blade has a moving blade edge on its surface facing the fixed blade. The starting thread hook groove and the separating thread hook groove are distributed on the same side of the moving blade edge.

[0007] Furthermore, the surface of the movable blade facing the fixed blade is also provided with a seam initiation groove and a seam post-seam groove. The seam initiation groove is connected between the seam initiation hook groove and the moving blade opening, and the seam post-seam groove is connected between the seam dividing hook groove and the moving blade opening.

[0008] Furthermore, the single-action anti-bird nest thread-cutting mechanism also includes a fixedly installed suction pipe, which has a suction port that can be aligned with the thread-cutting groove and / or the thread-cutting support groove.

[0009] Furthermore, the thread-cutting drive source is a motor; within a 360° range of one revolution of the motor shaft of the thread-cutting drive source, the thread-cutting drive source has a thread-cutting working area, and the thread-cutting working area has an initial rotation angle, a starting-seam knife-out rotation angle, a post-seam knife-out rotation angle, a starting-seam knife-back-thread-clamping rotation angle, and a thread-cutting rotation angle;

[0010] When the thread cutting drive source rotates to the starting stitch exit angle, the starting stitch hook groove is located directly below the needle;

[0011] When the thread cutting drive source rotates to the post-sewing blade exit angle, the thread-separating hook grooves are located directly below the needle;

[0012] When the thread cutting drive source operates to the starting and returning knife clamping angle, the surface thread of the movable knife is clamped, and the moving knife edge and the fixed knife edge do not engage.

[0013] When the wire cutting drive source operates to the wire cutting angle, the moving blade edge engages with the fixed blade edge.

[0014] Furthermore, the thread-cutting drive source is a motor; the thread-cutting drive assembly includes a thread-cutting shaft rotatably supported in the sewing machine base plate, a first transmission assembly drivingly connected between the thread-cutting drive source and the thread-cutting shaft, and a second transmission assembly drivingly connected between the thread-cutting shaft and the movable blade.

[0015] Furthermore, the first transmission assembly includes a first wire-cutting crank, a first wire-cutting connecting rod, and a second wire-cutting crank fixed on the motor shaft of the wire-cutting drive source, wherein the two ends of the first wire-cutting connecting rod are respectively hinged to the first wire-cutting crank and the second wire-cutting crank.

[0016] Furthermore, the second transmission assembly includes a third wire-cutting crank, a second wire-cutting connecting rod, and a movable blade holder fixed on the wire-cutting shaft. The two ends of the second wire-cutting connecting rod are respectively hinged to the third wire-cutting crank and the movable blade holder, and the movable blade is fixed on the movable blade holder.

[0017] Furthermore, the movable blade has a first pressing part on its surface facing the fixed blade, and the first pressing part is located on the side of the movable blade facing the seam hook groove.

[0018] When the thread cutting drive source drives the movable blade to rotate towards the fixed blade, so that the moving blade edge is close to the fixed blade edge and not engaged, the first thread pressing part abuts against the fixed blade and forms a first thread clamping seam for clamping the surface thread.

[0019] Furthermore, the single-moving-blade anti-bird nest thread-cutting mechanism also includes a fixedly installed thread-pressing plate. The thread-pressing plate, the fixed blade, and the movable blade are arranged sequentially from the outside to the inside along the radial direction of the rotary hook in the sewing machine. The movable blade has a second thread-pressing part on its surface facing the fixed blade. The second thread-pressing part is located on the side of the movable blade opening facing away from the starting stitch hook groove and protrudes towards the thread-pressing plate along the thickness direction of the movable blade.

[0020] When the wire cutting drive source drives the movable blade to rotate towards the fixed blade, so that the moving blade edge is close to the fixed blade edge and not engaged, the second pressing part can abut against the pressing plate and form a second clamping seam for holding the face thread.

[0021] This application also provides a control method for the above-mentioned single-acting blade anti-bird nest wire-cutting mechanism, which includes the following steps:

[0022] S1. Configure the controller to enable the wire-cutting drive source to communicate with the controller;

[0023] S2. During the process of the sewing machine starting the first stitch and the needle moving down, or before the sewing machine starts the first stitch, the controller controls the thread cutting drive source to operate, so that the movable knife rotates away from the fixed knife until the movable knife rotates to the starting stitch exit position, then the starting stitch hook groove rotates to directly below the needle.

[0024] S3. The sewing machine begins the first stitch by moving the needle downwards. The needle, carrying the thread, passes downwards into the thread hook groove. Under the action of the rotary hook in the sewing machine, the thread end moves to below the movable blade.

[0025] S4. When the sewing machine starts the first stitch, the needle moves upward. After the needle passes through the starting stitch hook groove, the controller controls the thread cutting drive source to run in reverse, causing the movable blade to rotate towards the fixed blade until the movable blade rotates to the starting stitch return blade clamping position. Then, the starting stitch hook groove, carrying the top thread end, rotates towards the fixed blade. The top thread end is accommodated on the surface of the movable blade and is clamped. Furthermore, the cutting edge of the movable blade and the cutting edge of the fixed blade do not engage.

[0026] S5. The sewing machine continues to start sewing with the set number of stitches;

[0027] S6. The controller controls the wire cutting drive source to continue to run in the reverse direction, so that the movable blade rotates towards the fixed blade until the movable blade rotates to the wire cutting position, then the blade edge of the movable blade engages with the blade edge of the fixed blade to cut off the end of the surface thread.

[0028] S7. The sewing machine is sewing normally.

[0029] S8. When the sewing machine finishes sewing and the thread needs to be cut, during the process of the sewing machine needle moving up while sewing the last stitch, the controller controls the thread cutting drive source to operate, causing the movable knife to rotate away from the fixed knife until the movable knife rotates to the post-sewing knife position to perform thread hooking and separation.

[0030] S9. The controller controls the wire cutting drive source to operate in reverse, causing the movable blade to rotate towards the fixed blade until the movable blade rotates to the wire cutting position. Then, the wire separating groove, carrying the top wire and bottom wire, rotates towards the fixed blade. The top wire is accommodated on the surface of the movable blade, and the top wire and bottom wire are cut off by the engagement of the movable blade edge and the fixed blade edge.

[0031] As described above, the single-acting blade anti-bird nest wire-cutting mechanism and its control method of the present invention have the following beneficial effects:

[0032] This application controls the stroke of the movable blade at the start and end of the sewing by controlling the different strokes of the thread-cutting drive source. This achieves the goal of cutting the top thread end during the start of the sewing and cutting the top thread at the end of the sewing, using the same thread-cutting drive source and the same set of movable and fixed blades to achieve the purpose of preventing bird's nests during the start of the sewing and automatically cutting the thread after sewing. Specifically, during the start of the sewing, the thread-cutting drive source drives the movable blade to move the top thread end closer to the fixed blade, but without engaging it. The top thread end on the surface of the movable blade can be clamped, meaning that the thread end is cut after setting the number of stitches for the start, effectively preventing thread slippage during the start of the sewing. This ensures a stable start of the sewing without bird's nests or tangled threads, guarantees a beautiful stitch, and reduces manual thread trimming. Furthermore, this application uses a single-moving blade structure, which is simple to implement, low in cost, easy to control, and has high control precision, improving the accuracy of thread cutting during the start and after sewing. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the assembly of the single-action anti-bird nest thread-cutting mechanism in the sewing machine.

[0034] Figure 2 and Figure 3 These are schematic diagrams of the single-acting anti-bird nest wire-cutting mechanism in this application from different perspectives.

[0035] Figure 4a This is a schematic diagram of the structure of the movable blade in Embodiment 1 of this application.

[0036] Figure 4b This is a schematic diagram of the structure of the movable blade in Embodiment 2 of this application.

[0037] Figure 4c This is a schematic diagram of the structure of the movable blade in Embodiment 3 of this application.

[0038] Figure 5 This is a schematic diagram of the clamping line between the movable blade and the fixed blade in this application.

[0039] Figure 6a This is a schematic diagram of the movable blade and the pressure plate clamping the wire in this application.

[0040] Figure 6b for Figure 6a Enlarged view of circle A.

[0041] Figure 7a This is a schematic diagram of the working angle of the wire-cutting drive source in this application. Figure 1 The corresponding figure Figure 4a Example 1 of the movable blade.

[0042] Figure 7b This is a schematic diagram of the working angle of the wire-cutting drive source in this application. Figure 2 The corresponding figure Figure 4b Example 2 of the movable blade.

[0043] Figure 8 This is a diagram showing the state of the single-action anti-bird's nest thread-cutting mechanism in this application when the knife is being extended at the start of the seam.

[0044] Figure 9 This is a diagram showing the state of the single-action anti-bird's nest thread-cutting mechanism in this application during the start-up and return-to-start stitching.

[0045] Figure 10 This is a diagram showing the state of the single-action anti-bird's nest thread-cutting mechanism in this application when the blade is extended after sewing.

[0046] Component designation explanation

[0047] 10 Fixed cutter

[0048] 101 Fixed cutting edge

[0049] 20 movable knives

[0050] 21. Seam opening groove

[0051] 22-way wire hook groove

[0052] 23 Moving edge

[0053] 24. Seam groove

[0054] 25. Post-seam groove

[0055] 26 First pressure line section

[0056] 27 Second pressure line section

[0057] 30 Wire Cutting Driver

[0058] 40 Wire Cutting Drive Component

[0059] 41 Thread cutting spool

[0060] 42 First Wire Cutting Crank

[0061] 43 First wire-cutting link

[0062] 44 Second Wire Cutting Crank

[0063] 45 Third Wire Cutting Crank

[0064] 46 Second wire-cutting link

[0065] 47. Moving tool holder

[0066] 50 Wire clamp

[0067] 60 suction pipe

[0068] 70 needles

[0069] 80 base plate

[0070] 90 Rotary Shuttle

[0071] 110 positioning hook

[0072] 120 motor bracket Detailed Implementation

[0073] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification.

[0074] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.

[0075] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.

[0076] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.

[0077] This application relates to the field of sewing machine technology, and in particular to a single-action anti-bird nest thread-cutting mechanism and a control method for the same mechanism. For ease of description, in the following embodiments, the directions are defined as follows: the axial directions of the main shaft and the lower shaft in the sewing machine are defined as left and right directions, with the left and right directions pointing towards the head of the machine and the right direction pointing towards the tail. The rotary hook 90 in the sewing machine is fixed to the left end of the lower shaft, as shown below. Figure 1 As shown, the direction in which the feeding mechanism drives the fabric to move during forward sewing is defined as the forward direction.

[0078] like Figures 1 to 3As shown, the single-action anti-bird nest thread-cutting mechanism involved in this application includes a fixed blade 10, a rotatable movable blade 20, a thread-cutting drive source 30, and a thread-cutting drive assembly 40. The fixed blade 10 is provided with a fixed blade edge 101. The thread-cutting drive source 30 is connected to the movable blade 20 through the thread-cutting drive assembly 40, driving the movable blade 20 to rotate towards or away from the fixed blade 10. In this embodiment, in the front-back direction, the fixed blade 10 is distributed on the rear side of the needle 70, and the fixed blade edge 101 is provided at the front end of the fixed blade 10. Figure 5 As shown; when the wire cutting drive source 30 drives the movable blade 20 to extend via the wire cutting drive assembly 40, the movable blade 20 rotates forward and moves away from the fixed blade 10; when the wire cutting drive source 30 drives the movable blade 20 to retract via the wire cutting drive assembly 40, the movable blade 20 rotates backward and moves closer to the fixed blade 10. Both the movable blade 20 and the fixed blade 10 are located on the lower side of the base plate 80 and on the outer periphery of the rotary hook 90. ​​Furthermore, the movable blade 20 is closer to the rotary hook 90 than the fixed blade 10, meaning the movable blade 20 is located below the fixed blade 10. A positioning hook 110 for limiting is provided on the rotary hook 90.

[0079] like Figure 4a or Figure 4b As shown, the movable blade 20 has a seam initiation groove 21 and a thread separating groove 22. Both the seam initiation groove 21 and the thread separating groove 22 extend through the movable blade 20 along its thickness direction. The seam initiation groove 21 allows the sewing machine needle 70 to pass through. A moving blade edge 23 is provided on the upper surface of the movable blade 20 facing the fixed blade 10. The seam initiation groove 21 and the thread separating groove 22 are located on the same side of the moving blade edge 23, i.e., both are located behind the moving blade edge 23. Along the direction away from the fixed blade 10 when the movable blade 20 extends, the arrangement of the seam initiation groove 21, the thread separating groove 22, and the moving blade edge 23 can be one of the following two: 1. As... Figure 4a As shown, in Embodiment 1 of the movable blade 20, along the direction away from the fixed blade 10 when the movable blade 20 extends, the seam initiation groove 21, the line dividing groove 22, and the moving blade edge 23 are distributed sequentially, that is, the seam initiation groove 21, the line dividing groove 22, and the moving blade edge 23 are distributed from back to front; II. As Figure 4b As shown, in Embodiment 2 of the movable blade 20, along the direction away from the fixed blade 10 when the movable blade 20 extends, the dividing line hook groove 22, the seam starting hook groove 21, and the moving blade edge 23 are distributed sequentially, that is, the dividing line hook groove 22, the seam starting hook groove 21, and the moving blade edge 23 are distributed from back to front.

[0080] This application also provides a control method for the above-mentioned single-acting blade anti-bird nest wire-cutting mechanism, which includes the following steps:

[0081] Step S1: Configure the controller so that the thread cutting drive source 30 communicates with the controller. At the same time, the main motor that drives the main shaft of the sewing machine also communicates with the controller. The left end of the main shaft drives the needle 70 to move up and down reciprocally through the needle bar mechanism.

[0082] Step S2: The sewing machine begins the first stitch, with the needle 70 moving down first and then up. During the downward movement of the needle 70, or before the needle 70 begins the first stitch, the controller controls the thread-cutting drive source 30 to operate. This, through the thread-cutting drive assembly 40, drives the movable blade 20 to extend, causing it to rotate forward away from the fixed blade 10 until it reaches the starting stitch position. At this point, if... Figure 8 As shown, the starting stitch hook groove 21 rotates to be directly below the needle 70. Preferably, the controller can control the thread cutting drive source 30 to operate when the sewing machine is turned on, or after the previous sewing is finished and the thread is cut, so that the movable blade 20 rotates to the starting stitch exit position, so that the starting stitch hook groove 21 has already rotated to be directly below the needle 70 before the sewing machine starts the first stitch.

[0083] Step S3: The sewing machine begins the first stitch with the needle 70 moving downwards. Since the starting stitch hook groove 21 is directly below the needle 70, the needle 70, carrying the top thread, passes down into the starting stitch hook groove 21. Under the action of the rotary hook 90 in the sewing machine, the end of the top thread moves to below the movable blade 20.

[0084] Step S4: The sewing machine continues to sew the first stitch, and the needle 70 moves upward. After the needle 70 passes through the starting stitch hook groove 21, the controller controls the thread cutting drive source 30 to rotate in the opposite direction. Through the thread cutting drive assembly 40, the movable blade 20 is driven to return to its original position, causing the movable blade 20 to rotate backward towards the fixed blade 10 until the movable blade 20 rotates to the starting stitch return position with the thread clamping mechanism. Figure 9 As shown, the starting stitch hook groove 21 rotates backward toward the fixed knife 10 with the top thread end, and the top thread end is accommodated on the surface of the movable knife 20 and is clamped; in particular, when the movable knife 20 is in the starting stitch return knife clamping position, the moving knife edge 23 and the fixed knife edge 101 do not engage, so the top thread end on the surface of the movable knife 20 is clamped but not cut.

[0085] Step S5: The sewing machine continues to sew the set number of stitches. During this process, the moving blade 23 and the fixed blade 101 remain in a non-engaged state. Figure 9 As shown, the thread end remains on the surface of the movable blade 20, is held in place, and is not cut off, effectively preventing the thread from coming loose.

[0086] Step S6: The controller controls the thread-cutting drive source 30 to continue rotating in the reverse direction, driving the movable blade 20 to continue retracting via the thread-cutting drive assembly 40. This causes the movable blade 20 to rotate backward towards the fixed blade 10 until it reaches the thread-cutting position. At this point, the moving blade edge 23 engages with the fixed blade edge 101, cutting off the thread end on the surface of the movable blade 20. Thus, through steps S2 to S6, the initial stitch cutting to prevent bird nests is achieved.

[0087] Step S7: The sewing machine sews normally.

[0088] Step S8: When the sewing machine finishes sewing and the thread needs to be cut, during the process of the sewing machine needle 70 moving upwards while sewing the last stitch, the controller simultaneously controls the thread cutting drive source 30 to operate. This drives the movable blade 20 to extend through the thread cutting drive assembly 40, causing the movable blade 20 to rotate forward away from the fixed blade 10 until it reaches the post-sewing exit position. Figure 10 As shown, draw lines to separate the lines.

[0089] Step S9: The controller controls the thread-cutting drive source 30 to rotate in reverse, driving the movable blade 20 back through the thread-cutting drive assembly 40. This causes the movable blade 20 to rotate backward towards the fixed blade 10 until it reaches the thread-cutting position. During this process, the thread-separating hook groove 22 rotates towards the fixed blade 10 with the top and bottom threads, and the top thread is accommodated on the surface of the movable blade 20. After the movable blade 20 reaches the thread-cutting position, the moving blade edge 23 engages with the fixed blade edge 101, cutting the top and bottom threads. Thus, through steps S8 and S9, automatic thread cutting at the end of sewing is achieved.

[0090] In this application, the movable blade 20 is equipped with a starting stitch hook groove 21 and a separating stitch hook groove 22. Combined with a controller that controls the thread-cutting drive source 30 to move at different strokes during the starting and ending stages of sewing, the stroke of the movable blade 20 is controlled. During the starting stitch, the movable blade 20 first rotates forward to the starting stitch exit position, then rotates backward with the top thread end to the starting stitch return position, and finally rotates backward to the thread-cutting position after setting the starting stitch count, thus cutting the top thread end during the starting stitch. During the thread-cutting at the end of sewing, the movable blade 20 first rotates forward to the sewing exit position, then rotates backward with the top thread to the thread-cutting position, achieving automatic thread cutting at the end of sewing. Therefore, this application achieves the goal of using the same thread-cutting drive source 30, and the same set of movable blades 20 and fixed blades 10 to achieve both starting stitch thread cutting (preventing nesting) and automatic thread cutting upon completion of sewing.

[0091] In particular, during the initial stitch cutting, the thread cutting drive source 30 drives the movable blade 20 to move the top thread end closer to the fixed blade 10 until it reaches the initial stitch return clamping position. The top thread end on the surface of the movable blade 20 is clamped, but the moving blade edge 23 and the fixed blade edge 101 do not engage. Instead, after setting the initial stitch count, the thread cutting drive source 30 drives the movable blade 20 to rotate the top thread end backward to the cutting position for thread cutting. This means that the initial stitch count is set first, and then the top thread end is cut. Furthermore, the top thread end is always clamped during the initial stitch count setting process, effectively preventing thread slippage during the initial stitch and achieving a stable initial stitch without any tangled threads, ensuring aesthetically pleasing stitches and reducing manual thread trimming. Additionally, this application uses a single-moving-blade structure, which is simple to implement and low in cost. The controller only controls the movable blade 20 by controlling the thread cutting drive source 30, making it easy to control and providing high control precision, thus improving the accuracy of initial stitch cutting and post-stitch thread cutting.

[0092] Based on the requirement that the thread end needs to be clamped during the initial sewing and thread cutting process, the single-acting blade anti-bird's nest thread cutting mechanism involved in this application further includes a thread clamping unit. When the movable blade 20 is located at the initial sewing and return blade thread clamping position, the thread clamping unit acts on the thread end on the surface of the movable blade 20, clamping the thread end on the surface of the movable blade 20. In this embodiment, the thread clamping unit has the following two preferred embodiments.

[0093] Example 1 of the wire clamping unit: The wire clamping unit is formed by a movable blade 20 and a fixed blade 10. For example... Figure 5 As shown, the movable blade 20 has a first pressing part 26 on its upper surface facing the fixed blade 10. The first pressing part 26 is located on the rear side of the movable blade edge 23 facing the starting stitch hook groove 21. When the thread cutting drive source 30 drives the movable blade 20 to rotate backward to the starting stitch return blade clamping position, the movable blade edge 23 is close to the fixed blade edge 101 but not engaged. The first pressing part 26 abuts against the fixed blade 10 and forms a first clamping seam for clamping the thread end. Thus, the first embodiment of the clamping unit is composed of the abutting first pressing part 26 and the fixed blade 10.

[0094] Embodiment 2 of the wire clamping unit: The wire clamping unit is formed by a movable blade 20 and a wire pressing plate 50. For example... Figure 6a and Figure 6bAs shown, the single-moving-blade anti-bird's nest thread-cutting mechanism also includes a fixedly installed pressure plate 50. The pressure plate 50, the fixed blade 10, and the movable blade 20 are arranged sequentially from the outside to the inside along the radial direction of the rotary hook 90 in the sewing machine. The pressure plate 50 is located above the fixed blade 10 and is fixed to the bottom of the base plate 80 by screws. The movable blade 20 has a second pressure part 27 on its surface facing the fixed blade 10. The second pressure part 27 is located on the front side of the movable blade edge 23 facing away from the starting stitch hook groove 21 and protrudes upward toward the pressure plate 50 along the thickness direction of the movable blade 20. The front end of the pressure plate 50 extends forward past the fixed blade edge 101 at the front end of the fixed blade 10. When the thread cutting drive source 30 drives the movable blade 20 to rotate backward to the starting and returning blade clamping position, the moving blade edge 23 is close to the fixed blade edge 101 but not engaged. The second pressing part 27 abuts against the pressing plate 50 and forms a second clamping seam for clamping the face thread. Thus, the second embodiment of the clamping unit is composed of the abutting second pressing part 27 and the pressing plate 50.

[0095] Preferably, such as Figure 4a or Figure 4b As shown, the movable blade 20 has a sewing thread inlet groove 24 and a sewing thread outlet groove 25 on its upper surface facing the fixed blade 10. The sewing thread inlet groove 24 connects between the sewing thread inlet hook groove 21 and the movable blade edge 23, that is, the rear end of the sewing thread inlet groove 24 extends rearward to the sewing thread inlet hook groove 21 and the front end extends forward to the movable blade edge 23; the sewing thread outlet groove 25 connects between the thread separating hook groove 22 and the movable blade edge 23, that is, the rear end of the sewing thread outlet groove 25 extends rearward to the thread separating hook groove 22 and the front end extends forward to the movable blade edge 23. Both the sewing thread inlet groove 24 and the sewing thread outlet groove 25 serve a guiding function. In the first embodiment of the movable blade 20, as... Figure 4a As shown, the post-seam thread-receiving groove 25 is the front section of the starting thread-receiving groove 24, and the thread-sewing hook groove 22 is arranged on the extension path of the starting thread-receiving groove 24; when cutting the thread at the start of the seam, the starting thread-receiving groove 24 contains the top thread end, and a portion of the top thread end is simultaneously contained in the post-seam thread-receiving groove 25, which constitutes the front section of the starting thread-receiving groove 24; when cutting the thread after sewing, the post-seam thread-receiving groove 25 contains both the top thread and the bottom thread. In the second embodiment of the movable blade 20, as... Figure 4b As shown, the starting seam thread groove 24 is the front part of the sewing thread groove 25, and the starting seam hook groove 21 is set on the extension path of the sewing thread groove 25. When the starting seam thread is cut, the starting seam thread groove 24 contains the top thread end. When the sewing thread is cut, the sewing thread groove 25 contains the top thread and the bottom thread. Thus, a portion of the top thread and the bottom thread are simultaneously contained in the starting seam thread groove 24, which constitutes the front part of the sewing thread groove 25.

[0096] Furthermore, such as Figures 4a to 4c As shown, the seam guide groove 22 is an open groove facing left, while the seam guide groove 21 can be either an open groove or a closed groove; for example: Figure 4a and Figure 4b In the movable knife 20 shown, the seam hook groove 21 is a closed groove; Figure 4c In the movable blade 20 shown, the seam-starting hook groove 21 is an opening groove that opens to the rear; in other embodiments, the seam-starting hook groove 21 can also be an opening groove that opens to the left.

[0097] Furthermore, such as Figure 2 and Figure 3 As shown, the single-action bird nest prevention and thread-cutting mechanism also includes a fixedly installed suction pipe 60, which is fixed to the bottom of the base plate 80 by screws. The suction pipe 60 has a suction port that can be aligned with the thread-hooking groove 21 and / or the thread-receiving groove 24. The suction pipe 60 is connected to an air source generator, which is in turn connected to a controller. During the process of preventing bird nests by cutting the thread, when the controller controls the thread-cutting drive source 30 to drive the movable blade 20 to rotate forward, the controller also controls the air source generator to start, so that a negative pressure is generated at the suction port of the suction pipe 60 to suck up the thread. In this way, when the movable blade 20 drives the thread end to rotate backward to the thread-clamping position of the thread-hooking return blade, the thread end in the thread-hooking groove 21 is exactly in the negative pressure area of ​​the suction port, realizing the pickup of the thread end. After cutting the thread, the cut thread end is sucked away by the negative pressure of the suction port, realizing the collection of the thread end.

[0098] Preferably, such as Figure 1 As shown, the fixed blade 10 is fixed to the bottom of the sewing machine base plate 80 by screws, thus achieving a fixed setting of the fixed blade 10. In this way, the fixed blade 10, the pressure plate 50, and the suction pipe 60 can be fixed to the bottom of the base plate 80 by the same screw.

[0099] Furthermore, the wire-cutting drive source 30 drives the movable blade 20 to rotate around the lower axis via the wire-cutting drive assembly 40, meaning the rotation center of the movable blade 20 is the lower axis. For example... Figure 2 and Figure 3 As shown, the wire-cutting drive source 30 is a motor, preferably a stepper motor. The wire-cutting drive source 30 is fixed on the motor bracket 120, which is fixed to the bottom of the base plate 80 by several screws. Of course, the wire-cutting drive source 30 can also be directly fixed to the bottom of the base plate 80 by several screws.

[0100] Furthermore, such as Figure 2 and Figure 3As shown, the thread-cutting drive assembly 40 includes a thread-cutting shaft 41 rotatably supported in the sewing machine base plate 80, a first transmission assembly drivingly connected between the thread-cutting drive source 30 and the right end of the thread-cutting shaft 41, and a second transmission assembly drivingly connected between the left end of the thread-cutting shaft 41 and the movable blade 20. The thread-cutting shaft 41 is parallel to the lower shaft and is rotatably supported in the sewing machine base plate 80 by a bushing. The thread-cutting drive source 30 drives the thread-cutting shaft 41 to rotate via the first transmission assembly, and the thread-cutting shaft 41 drives the movable blade 20 to rotate via the second transmission assembly.

[0101] Furthermore, such as Figure 2 and Figure 3 As shown, the first transmission assembly includes a first wire-cutting crank 42, a first wire-cutting connecting rod 43, and a second wire-cutting crank 44 fixed to the right end of the wire-cutting shaft 41, all fixed to the motor shaft of the wire-cutting drive source 30. The two ends of the first wire-cutting connecting rod 43 are hinged to the first wire-cutting crank 42 and the second wire-cutting crank 44, respectively. The second transmission assembly includes a third wire-cutting crank 45, a second wire-cutting connecting rod 46, and a movable blade holder 47 fixed to the left end of the wire-cutting shaft 41. The two ends of the second wire-cutting connecting rod 46 are hinged to the third wire-cutting crank 45 and the movable blade holder 47, respectively. The movable blade 20 is fixed to the movable blade holder 47 by screws.

[0102] Furthermore, such as Figure 7a or Figure 7b As shown, within the 360° range of one revolution of the motor shaft of the thread-cutting drive source 30, the thread-cutting drive source 30 has a thread-cutting working area P, which includes an initial rotation angle α1, a starting-seam exit angle α2, a post-seam exit angle α3, a starting-seam return-line clamping angle α4, and a thread-cutting angle α5. For... Figure 4a The first embodiment of the movable blade 20 shown is as follows: Figure 7a As shown, the initial turning angle α1, the thread-cutting turning angle α5, the starting-seam return-to-the-knife-clamping-line turning angle α4, the post-seam exit-to-the-knife turning angle α3, and the starting-seam exit-to-the-knife turning angle α2 are set sequentially, and the range of the thread-cutting working area P is α1~α2. For Figure 4b The second embodiment of the movable blade 20 shown is as follows: Figure 7bAs shown, the initial turning angle α1, the thread-cutting turning angle α5, the starting-seam return-to-the-knife-clamping-line turning angle α4, the starting-seam exit-to-the-knife turning angle α2, and the post-seam exit-to-the-knife turning angle α3 are set sequentially, and the range of the thread-cutting working area P is α1 to α3. When the thread-cutting drive source 30 rotates to the starting-seam exit-to-the-knife turning angle α2, the movable knife 20 rotates to the starting-seam exit-to-the-knife position, and the starting-seam hook groove 21 is located directly below the needle 70. When the thread-cutting drive source 30 rotates to the post-seam exit-to-the-knife turning angle α3, the movable knife 20 rotates to the post-seam exit-to-the-knife position, and the thread-seam hook groove 22 is located directly below the needle 70. When the thread-cutting drive source 30 rotates to the starting-seam return-to-the-knife-clamping-line turning angle α4, the movable knife 20 rotates to the starting-seam return-to-the-knife-clamping-line position, the top thread in the starting-seam thread-receiving groove 24 is clamped, and the moving blade edge 23 and the fixed blade edge 101 are not engaged. When the wire cutting drive source 30 operates to the wire cutting angle α5, the movable blade 20 rotates to the wire cutting position, and the moving blade edge 23 engages with the fixed blade edge 101.

[0103] In summary, the working principle of the single-acting blade anti-bird nest wire-cutting mechanism involved in this application is as follows, taking the first embodiment with the movable blade 20 and the wire pressing plate 50 as an example.

[0104] I. A single-action anti-bird nest thread-cutting mechanism is used to cut threads at the start of a seam to prevent bird nests from nesting. It includes the following steps:

[0105] A1. When the sewing machine is working, the main shaft rotates, and the first stitch is started. The controller controls the thread cutting drive source 30 to move synchronously. The thread cutting drive source 30 rotates to the starting cutter angle α2, driving the movable blade 20 forward to the starting cutter position, so that the starting thread hook groove 21 rotates directly below the needle 70. Alternatively, before the sewing machine starts the first stitch, the controller has already controlled the thread cutting drive source 30 to rotate to the starting cutter angle α2, so that the starting thread hook groove 21 has already rotated directly below the needle 70. At the same time, the controller controls the air source generator to operate, so that a negative pressure is generated at the air inlet of the suction pipe 60 to suck up the thread.

[0106] A2. When the sewing machine starts the first stitch, the needle 70 moves down and passes through the starting stitch hook groove 21 with the top thread. Under the action of the rotary hook 90, the top thread end on one side of the needle 70 is moved to the bottom of the movable blade 20.

[0107] A3. When the sewing machine starts the first stitch, the needle 70 moves upward. After the needle 70 moves upward away from the movable blade 20, the controller controls the thread cutting drive source 30 to rotate in the opposite direction from the starting stitch exit angle α2 to the starting stitch return angle α4. The movable blade 20, carrying the top thread end, retracts to the starting stitch return position. Then, the pressure plate 50 and the second pressure part 27 of the movable blade 20 come into contact, clamping the top thread end in the starting stitch receiving groove 24. The thread end of the top thread in the starting stitch receiving groove 24 is exactly in the negative pressure area of ​​the air intake, realizing the pickup of the thread end. The moving blade edge 23 and the fixed blade edge 101 are in a non-engaging state, so the top thread end is only clamped and not cut.

[0108] A4. After the sewing machine continues to start the set number of stitches, the controller controls the thread cutting drive source 30 to continue rotating in the opposite direction from the starting stitch return knife clamping angle α4 to the thread cutting angle α5. The movable blade 20 rotates backward with the top thread end to the thread cutting position. The moving blade edge 23 engages with the fixed blade edge 101 to cut the top thread end in the starting stitch receiving groove 24. The cut top thread end is sucked away and collected by the negative pressure of the suction port.

[0109] A5. The controller controls the thread cutting drive source 30 to continue rotating in the opposite direction from the thread cutting angle α5 to the initial angle α1, the movable blade 20 returns to its initial position, the controller controls the air source generator to stop operating, and the suction pipe 60 disconnects the suction; then, the sewing machine sews according to the set state.

[0110] II. The single-action anti-bird's nest thread-cutting mechanism is used to cut threads at the end of sewing, and includes the following steps:

[0111] B1. When the sewing machine sews the last stitch, as the needle 70 moves upward, the controller controls the thread cutting drive source 30 to move synchronously. The thread cutting drive source 30 rotates to the post-sewing knife exit angle α3, driving the movable knife 20 to rotate forward to the post-sewing knife exit position, and the thread separating groove 22 realizes the thread separation.

[0112] B2. The controller controls the thread cutting drive source 30 to rotate in the opposite direction from the back-end blade angle α3 to the thread cutting angle α5. The movable blade 20 rotates backward with the top thread and bottom thread to the thread cutting position. The moving blade edge 23 engages with the fixed blade edge 101 to cut the top thread and bottom thread in the back-end thread receiving groove 25.

[0113] Therefore, the single-acting anti-bird nest wire-cutting mechanism involved in this application has the following advantages:

[0114] 1. The movable blade 20 is equipped with a starting seam hook groove 21, a separating seam hook groove 22, a starting seam thread receiving groove 24, and a sewing thread receiving groove 25. The same set of movable blades 20 and fixed blades 10 work together to achieve two functions: cutting the thread at the starting seam to prevent bird nests and automatically cutting the thread after sewing.

[0115] 2. After starting the stitch, bring the top thread end to one side of the needle 70 and hold it while waiting. During the waiting process, always hold the top thread end. Cut the top thread end after the set number of stitches for starting the stitch. The waiting time for cutting the top thread end is precisely controlled according to the set number of stitches. This can prevent the thread from coming loose during the starting stitch and also prevent bird's nest-like tangles from forming during the starting stitch.

[0116] 3. It adopts stepper motor drive, which ensures stable and reliable wire cutting with low wire cutting noise.

[0117] In the above embodiments, the fixed blade 10, the movable blade 20, the pressure plate 50, and the suction pipe 60 are all arranged on the rear side of the needle 70; in other embodiments, the fixed blade 10, the movable blade 20, the pressure plate 50, and the suction pipe 60 can also be symmetrically arranged on the front side of the needle 70 along the central axis of the rotary hook, in which case the movable blade 20 swings backward when it extends and swings forward when it retracts.

[0118] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0119] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A single-acting blade anti-bird nest wire cutting mechanism, comprising a fixed blade (10), a rotatable movable blade (20), a wire cutting drive source (30), and a wire cutting drive assembly (40), wherein the fixed blade (10) is provided with a fixed blade edge (101), and the wire cutting drive source (30) is connected to the movable blade (20) through the wire cutting drive assembly (40) to drive the movable blade (20) to rotate toward or away from the fixed blade (10), characterized in that: The movable blade (20) has a starting stitch hook groove (21) and a separating stitch hook groove (22). The starting stitch hook groove (21) allows the sewing machine needle (70) to pass through. The movable blade (20) has a moving blade edge (23), a starting stitch receiving groove (24), and a sewing thread receiving groove (25) on the surface facing the fixed blade (10). The starting stitch hook groove (21) and the separating stitch hook groove (22) are distributed on the same side of the moving blade edge (23). The starting stitch receiving groove (24) is connected between the starting stitch hook groove (21) and the moving blade edge (23). The sewing thread receiving groove (25) is connected between the separating stitch hook groove (22) and the moving blade edge (23). The thread-cutting drive source (30) is a motor; within the range of 360° rotation of the motor shaft of the thread-cutting drive source (30), the thread-cutting drive source (30) has a thread-cutting working area (P), and the thread-cutting working area (P) has an initial rotation angle (α1), a starting-seam exiting-knife rotation angle (α2), a sewing-after-seam exiting-knife rotation angle (α3), a starting-seam return-knife clamping-thread rotation angle (α4), and a thread-cutting rotation angle (α5). When the thread cutting drive source (30) operates to the starting cutter angle (α2), the starting cut hook groove (21) is located directly below the needle (70); When the thread cutting drive source (30) operates to the post-sewing knife exit angle (α3), the thread-separating hook groove (22) is located directly below the needle (70); When the thread cutting drive source (30) operates to the starting and returning knife clamping angle (α4), the surface line of the movable knife (20) is clamped, and the moving knife edge (23) and the fixed knife edge (101) do not engage. When the wire cutting drive source (30) operates to the wire cutting angle (α5), the moving blade edge (23) engages with the fixed blade edge (101).

2. The single-acting blade anti-bird nest wire-cutting mechanism according to claim 1, characterized in that: It also includes a fixedly installed suction pipe (60) having a suction port that can be aligned with the seam hook groove (21) and / or the seam allowance groove (24).

3. The single-acting blade anti-bird nest wire-cutting mechanism according to claim 1, characterized in that: The thread-cutting drive source (30) is a motor; the thread-cutting drive assembly (40) includes a thread-cutting shaft (41) rotatably supported in the sewing machine base plate (80), a first transmission assembly connected between the thread-cutting drive source (30) and the thread-cutting shaft (41), and a second transmission assembly connected between the thread-cutting shaft (41) and the movable blade (20).

4. The single-acting blade anti-bird nest wire-cutting mechanism according to claim 3, characterized in that: The first transmission assembly includes a first wire cutting crank (42) fixed on the motor shaft of the wire cutting drive source (30), a first wire cutting connecting rod (43), and a second wire cutting crank (44) fixed on the wire cutting shaft (41). The two ends of the first wire cutting connecting rod (43) are respectively hinged to the first wire cutting crank (42) and the second wire cutting crank (44).

5. The single-acting blade anti-bird nest wire-cutting mechanism according to claim 3, characterized in that: The second transmission assembly includes a third wire-cutting crank (45), a second wire-cutting connecting rod (46), and a movable blade holder (47) fixed on the wire-cutting shaft (41). The two ends of the second wire-cutting connecting rod (46) are respectively hinged to the third wire-cutting crank (45) and the movable blade holder (47), and the movable blade (20) is fixed on the movable blade holder (47).

6. The single-acting blade anti-bird nest wire-cutting mechanism according to claim 1, characterized in that: The movable blade (20) has a first pressing part (26) on its surface facing the fixed blade (10). The first pressing part (26) is located on the side of the movable blade edge (23) facing the seam hook groove (21). When the wire cutting drive source (30) drives the movable blade (20) to rotate toward the fixed blade (10), so that the moving blade edge (23) is close to the fixed blade edge (101) and not engaged, the first pressing part (26) abuts against the fixed blade (10) and forms a first clamping seam for clamping the face thread.

7. The single-acting blade anti-bird nest wire-cutting mechanism according to claim 1, characterized in that: It also includes a fixedly installed pressure plate (50), the pressure plate (50), the fixed knife (10) and the movable knife (20) are arranged sequentially from the outside to the inside along the radial direction of the rotary hook (90) in the sewing machine; the movable knife (20) has a second pressure part (27) on the surface facing the fixed knife (10), the second pressure part (27) is located on the side of the movable knife edge (23) facing away from the starting stitch hook groove (21) and protrudes towards the pressure plate (50) along the thickness direction of the movable knife (20); When the wire cutting drive source (30) drives the movable blade (20) to rotate toward the fixed blade (10), so that the moving blade edge (23) is close to the fixed blade edge (101) and not engaged, the second pressing part (27) can abut against the pressing plate (50) and form a second clamping seam for holding the face thread.

8. A control method for the single-acting blade anti-bird nest wire-cutting mechanism as described in claim 1, characterized in that: The steps are as follows: S1. Configure the controller to make the wire-cutting drive source (30) communicate with the controller; S2. During the process of the sewing machine starting the first stitch needle (70) moving down, or before the sewing machine starting the first stitch needle (70), the controller controls the thread cutting drive source (30) to operate, so that the movable blade (20) rotates away from the fixed blade (10) until the movable blade (20) rotates to the starting stitch exit position, then the starting stitch hook groove (21) rotates to directly below the needle (70); S3. The sewing machine needle (70) moves down to start the first stitch, and the needle (70) carries the top thread and goes down into the starting stitch hook groove (21). Under the action of the rotary hook (90) in the sewing machine, the top thread end moves to below the movable blade (20). S4. The sewing machine needle (70) moves upward to start the first stitch. After the needle (70) passes through the starting stitch hook groove (21) upward, the controller controls the thread cutting drive source (30) to run in reverse, so that the movable blade (20) rotates towards the fixed blade (10) until the movable blade (20) rotates to the starting stitch return blade clamping position. Then the starting stitch hook groove (21) rotates towards the fixed blade (10) with the top thread end. The top thread end is accommodated on the surface of the movable blade (20) and is clamped. Furthermore, the moving blade edge (23) and the fixed blade edge (101) do not engage. S5. The sewing machine continues to start sewing with the set number of stitches; S6. The controller controls the wire cutting drive source (30) to continue to run in the reverse direction, so that the movable blade (20) rotates towards the fixed blade (10) until the movable blade (20) rotates to the wire cutting position, then the moving blade edge (23) and the fixed blade edge (101) engage to cut the end of the surface thread; S7. The sewing machine is sewing normally. S8. When the sewing machine finishes sewing and the thread needs to be cut, during the process of the sewing machine needle (70) moving up while sewing the last stitch, the controller controls the thread cutting drive source (30) to operate, so that the movable blade (20) rotates away from the fixed blade (10) until the movable blade (20) rotates to the post-sewing blade position to perform thread hooking and thread separation. S9. The controller controls the wire cutting drive source (30) to run in reverse, causing the movable blade (20) to rotate towards the fixed blade (10) until the movable blade (20) rotates to the wire cutting position. Then the wire separating groove (22) rotates towards the fixed blade (10) with the top and bottom wires. The top wire is housed on the surface of the movable blade (20) and the top and bottom wires are cut by the engagement of the movable blade edge (23) and the fixed blade edge (101).

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