Thread trimming mechanism of sewing machine, and sewing machine

Abstract

The present invention relates to a thread trimming mechanism of a sewing machine, and a sewing machine, wherein the thread trimming mechanism comprises a first thread trimmer and a second thread trimmer, wherein the first thread trimmer is fixedly mounted on the outer peripheral side of a rotary hook assembly, the second thread trimmer is arranged on the outer peripheral side of the rotary hook assembly and can rotate around the rotary hook assembly to engage with or separate from the second thread trimmer, the second thread trimmer is provided with a thread trimming hook for hooking the bottom thread and the top thread and moving them toward the first thread trimmer, the thread trimming mechanism further comprises a fixedly mounted thread trimming catcher, the thread trimming catcher is provided with a first constraint structure, and the second thread trimmer is provided with a second constraint structure; when thread trimming starts, the second thread trimmer rotates toward the first thread trimmer and the thread trimming hook drives the top thread to approach the first constraint structure, and before the second thread trimmer engages with the first thread trimmer to cut the thread, the second constraint structure cooperates with the first constraint structure and constrains the cloth edge thread in the top thread loop to a fixed and unchanging thread trimming constraint position.

Description

Technical Field

[0001] The present invention relates to the field of sewing equipment, and in particular to a thread trimming mechanism of a sewing machine and a sewing machine. Background Art

[0002] In existing sewing machines, the thread trimming mechanism uses a thread dividing piece to separate the threads when trimming the threads. Figure 1 The upper thread loop may wrap around the existing thread divider 01 or may be completely on the bevel side of the existing thread divider 01. This will cause the length of the upper thread 9 on the right side of the needle to be very unstable after thread trimming. The unstable length of the upper thread 9 on the right side of the needle may be too short to form an upper thread loop, further increasing the probability that the sewing belt will not be able to reach the lower thread 10, and may even cause the sewing thread to slip out of the needle hole during sewing. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the technical problem to be solved by the present invention is to provide a thread trimming mechanism for a sewing machine, and a sewing machine, which can limit the position of the fabric edge line in the upper thread loop when trimming the thread, improve the stability of the upper thread loop when trimming the thread, and make the length of the thread end basically consistent after trimming the thread.

[0004] To achieve the above-mentioned object, the present invention provides a thread trimming mechanism of a sewing machine, which is arranged at a rotary hook assembly of the sewing machine for thread cutting, the thread trimming mechanism comprising a first thread trimmer and a second thread trimmer, the first thread trimmer being fixedly mounted on the outer peripheral side of the rotary hook assembly, the second thread trimmer being arranged on the outer peripheral side of the rotary hook assembly and being capable of rotating around the rotary hook assembly until engaging with or separating from the second thread trimmer, the second thread trimmer being provided with a thread trimming hook for hooking the bottom thread and the top thread and moving them toward the first thread trimmer, the thread trimming mechanism further comprising a fixedly mounted thread trimming catcher, the thread trimming catcher being provided with a first restraining structure, and the second thread trimmer being provided with a second restraining structure; when thread cutting starts, the second thread trimmer rotates toward the first thread trimmer and the thread trimming hook drives the top thread to approach the first restraining structure, and before the second thread trimmer engages with the first thread trimmer to cut the thread, the second restraining structure cooperates with the first restraining structure and restrains the cloth edge thread in the top thread loop at a fixed thread trimming restraining position.

[0005] Furthermore, the thread cutting hook of the second thread cutter is composed of a thread hook bevel and a thread hook guard, the thread hook bevel extends obliquely to the right from the left side of the second thread cutter, and the thread hook guard is arranged on the right side of the thread hook bevel, and the second constraint structure includes a thread cutting hook; the thread cutting catcher includes an arc-shaped capture piece arranged along the outer peripheral side of the rotary hook assembly, and the arc-shaped capture piece is located between the rotary hook assembly and the first thread cutter, one end of the arc-shaped capture piece facing the second thread cutter is the A side end, and the other end is the B side end, the first constraint structure includes a constraint side edge arranged on the right side of the A side end of the arc-shaped capture piece and inclined to the right, the constraint side edge is opposite to the thread cutting hook, and the side of the constraint side edge close to the A side end extends to the left side of the thread hook bevel; when the second thread cutter rotates toward the first thread cutter, the thread cutting hook and the constraint side edge intersect to form a closed area.

[0006] Furthermore, when the second thread cutter rotates to engage with the first thread cutter to cut the thread, the closed area formed by the intersection of the thread cutting hook and the restraining side edge still exists.

[0007] Furthermore, when the second thread cutter rotates to engage with the first thread cutter to cut the thread, the thread cutting hook crosses the restraining side edge so that the closed area disappears.

[0008] Furthermore, the line hooking retaining edge is tilted left and right, with one end close to the line trimming and catching member located on the left side and the other end away from the line trimming and catching member located on the right side.

[0009] Furthermore, the second thread cutter is provided with a thread dividing tip for inserting between the upper thread loops to divide the thread, the left side of the thread dividing tip is a thread hooking edge, and the right side of the thread dividing tip has a first thread dividing bevel inclined to the right.

[0010] Furthermore, the right side of the arc-shaped capture piece is provided with a second dividing line bevel opposite to the first dividing line bevel, and when the second wire cutter rotates toward the first wire cutter, the first dividing line bevel and the second dividing line bevel intersect; the second constraint structure also includes the first dividing line bevel, and the first constraint structure also includes the second dividing line bevel.

[0011] Furthermore, an arc-shaped protrusion is provided on the right side of the arc-shaped capturing piece, and the arc-shaped protrusion is located on the left side of the hook line retaining edge, and the end of the constraint side close to the B side end extends to the arc-shaped protrusion.

[0012] Furthermore, a first catching portion is provided on the side of the first thread trimmer facing the rotary hook assembly, and a second catching portion is provided on the outer arc surface of the arc-shaped catching piece, which abuts against the first catching portion; when trimming the thread, the second thread trimmer rotates toward the first thread trimmer and causes the thread trimming hook to drive the bottom line to extend between the first catching portion and the second catching portion.

[0013] Furthermore, the line hooking rib is tilted left and right, with one end close to the line trimming catch part on the left and one end away from the line trimming catch part on the right. The end of the line hooking rib close to the line trimming catch part is on the right side of the second capture part.

[0014] Furthermore, the inclination angle of the hooking edge relative to the front-back direction is 2 to 4 degrees.

[0015] Furthermore, the inclination angle of the hook line retaining edge relative to the front-back direction is 3°.

[0016] Furthermore, the first thread cutter is provided with a lifting portion, and the second thread cutter is provided with a lifting portion inclined toward the side where the rotary hook assembly is located. When the second thread cutter rotates toward the first thread cutter, the lifting portion is inserted into the lower side of the lifting portion facing the rotary hook assembly.

[0017] Furthermore, the thread trimmer catch member has a mounting section connected to the arc-shaped catch piece, the component used for fixed installation of the thread trimmer catch member in the sewing machine is a catch member mounting base, and the mounting section is fixedly connected to the catch member mounting base.

[0018] Furthermore, the mounting section is fixedly mounted on the capture member mounting base by means of fastening screws, the mounting section is provided with a strip-shaped connecting hole extending in the front-to-back direction, and the fastening screws pass through the strip-shaped connecting hole and are screwed into the capture member mounting base.

[0019] The present invention also provides a sewing machine, comprising a rotary hook assembly and the above-mentioned thread trimming mechanism, wherein the thread trimming mechanism is arranged at the rotary hook assembly for thread trimming.

[0020] As described above, the thread trimming mechanism and sewing machine according to the present invention have the following beneficial effects:

[0021] By setting a thread trimming catch piece, the upper thread is constrained by the first constraint structure on the arc-shaped capture piece and the second constraint structure on the second thread trimmer. When trimming the thread, the second thread trimmer is driven to rotate toward the first thread trimmer, and the thread trimming hook will hook the bottom thread and the fabric edge thread in the upper thread loop, and then drive the bottom thread and the upper thread close to the first thread trimmer. At the same time, the upper thread loop will be close to the first constraint structure on the thread trimming catch piece, and the second constraint structure will also be close to the first constraint structure. Before biting and cutting the thread, the second constraint structure cooperates with the first constraint structure to constrain the fabric edge thread in the upper thread loop to a fixed and unchanging thread trimming constraint position, and then biting and cutting the thread, which can limit the upper thread loop to a stable position each time the thread is trimmed, improve the stability of the upper thread loop when trimming the thread, and make the thread head length basically consistent after thread trimming. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the position of the surface wire loop on the branching plate in the existing design.

[0023] Figure 2 It is a structural schematic diagram of the thread cutting mechanism of the present invention.

[0024] Figure 3 Schematic diagram of the structure of the second thread cutter in the thread cutting mechanism of the present invention.

[0025] Figure 4 Schematic diagram of the structure of the first thread cutter in the thread cutting mechanism of the present invention.

[0026] Figure 5 Schematic diagram of the structure of a certain embodiment of the thread trimming and catching member in the present invention.

[0027] Figure 6 Schematic diagram of the structure of another embodiment of the thread trimming and catching member in the present invention.

[0028] Figure 7 This is a schematic diagram of the operation of the thread trimming mechanism of the present invention during normal sewing and bobbin thread catching.

[0029] Figure 8 The figure is a schematic diagram of the working of the thread trimming mechanism of the present invention when trimming the thread.

[0030] Figure 9 Schematic diagram of the cooperation between the first thread trimmer and the thread trimming catcher in state 1 during thread trimming in the present invention.

[0031] Figure 10 Schematic diagram of the cooperation between the first thread trimmer and the thread trimming catcher in the second state during thread trimming in the present invention.

[0032] Figure 11 Schematic diagram of the cooperation between the first thread trimmer and the thread trimming catcher in state three during thread trimming in the present invention.

[0033] Figure 12 Schematic diagram of the position of the upper thread end at the thread trimming and catching member in the present invention.

[0034] Figure 13 The figure is a schematic diagram of the working of the thread trimming mechanism of the present invention when trimming the thread.

[0035] Figure 14 The figure is a schematic diagram of the working state of the thread trimming mechanism of the present invention after thread trimming.

[0036] Component number description

[0037] 01 Breakout Plate

[0038] 1. Chassis

[0039] 2 Hook assembly

[0040] 2a Hook liner

[0041] 2b shuttle leather 2b

[0042] 2c Shuttle thread guide

[0043] 3 Hook positioning hook

[0044] 4 needles

[0045] 5. First Thread Cutter

[0046] 5a First Cut

[0047] 5b First capture unit

[0048] 5c Elevation

[0049] 6 Second thread cutter

[0050] 6a Second cutting edge

[0051] 6b Thread trimmer hook

[0052] 6c hook line bevel

[0053] 6d hook line retaining edge

[0054] 6e branch line tip

[0055] 6f Hypotenuse of the first bisection

[0056] 6g lift

[0057] 7 Thread trimmer catch

[0058] 71 arc capture piece

[0059] 711 A side end

[0060] 712 B side end

[0061] 71a Constrained Sides

[0062] 71b Second bisection hypotenuse

[0063] 71c Second capture unit

[0064] 71d arc convex

[0065] 72 Installation Section

[0066] 72a Strip connection hole

[0067] 8 Thread trimmer drive assembly

[0068] 9. Noodles

[0069] 9a Selvedge

[0070] 9b Needle Edge

[0071] 10. Bottom Line

[0072] 11 Fastening screws DETAILED DESCRIPTION

[0073] The following describes the implementation of the present invention through specific embodiments. People skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0074] It should be noted that the structures, proportions, sizes, etc. depicted in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the conditions for the implementation of the present invention. Therefore, they have no substantial technical significance. Any modification of the structure, change in the proportional relationship, or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the efficacy and purpose of the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle", etc. quoted in this specification are only for the convenience of description and are not used to limit the scope of the implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0075] See also Figures 1 to 14 The present invention provides a thread trimming mechanism of a sewing machine, which is used to be arranged at a rotary hook assembly 2 of the sewing machine for thread trimming. The rotary hook assembly 2 is positioned and installed by a rotary hook positioning hook 3, and the rotary hook positioning hook 3 is fixed on the casing 1. The outermost part of the rotary hook assembly 2 is a rotary shuttle skin 2b.

[0076] The thread trimming mechanism of the present invention includes a first thread trimmer 5 and a second thread trimmer 6. The first thread trimmer 5 and the second thread trimmer 6 can both be arc-shaped blades. The first thread trimmer 5 is fixedly mounted on the outer peripheral side of the rotary hook assembly 2, and the second thread trimmer 6 is disposed on the outer peripheral side of the rotary hook assembly 2 and can rotate around the rotary hook assembly 2 to engage with or separate from the second thread trimmer 6. That is, the first thread trimmer 5 and the second thread trimmer 6 are both located above the shuttle skin 2b and have a certain gap therebetween. When the shuttle skin 2b rotates, they will not touch the first thread trimmer 5 and the second thread trimmer 6. The rotation of the first thread trimmer 5 is driven by the thread trimming drive assembly 8. The second thread trimmer 6 is provided with a thread trimming hook 6b for hooking the bottom thread 10 and the top thread 9 toward the first thread trimmer 5, see Figure 2 and Figure 7 The thread trimming hook 6b is located below the needle 4. When the second thread trimmer 6 rotates, it will hook the bottom thread 10 and the edge thread 9a in the upper thread loop, and push both the bottom thread 10 and the upper thread 9 to the first thread trimmer 5. Then the second blade 6a on the second thread trimmer 6 engages with the first blade 5a on the first thread trimmer 5, cutting the bottom thread 10 and the edge thread 9a in the upper thread loop.

[0077] The thread trimming mechanism of the present invention also includes a fixedly installed thread trimming catcher 7, which can be specifically installed on the casing 1 or the rotary hook positioning hook 3 and other components fixed to the casing 1. The thread trimming catcher 7 is provided with a first constraint structure, which is located at the position of the first thread trimmer 5, and the second thread trimmer 6 is provided with a second constraint structure; when the thread trimming starts, the second thread trimmer 6 rotates toward the first thread trimmer 5, and the thread trimming hook 6b drives the upper thread 9 close to the first constraint structure, and before the second thread trimmer 6 and the first thread trimmer 5 engage in thread cutting, the second constraint structure cooperates with the first constraint structure and constrains the fabric edge line 9a in the upper thread loop to a fixed thread trimming constraint position.

[0078] The thread trimming mechanism of the present invention works normally. Figure 7 , the second thread trimmer 6 does not move and is away from the first thread trimmer 5, and the rotary hook assembly 2 can rotate normally. When it is necessary to trim the thread, the thread trimming drive assembly 8 is used to drive the second thread trimmer 6 to rotate toward the first thread trimmer 5. The thread trimming hook 6b will hook the bottom thread 10 and the fabric edge thread 9a in the upper thread loop, and then drive the bottom thread 10 and the upper thread 9 close to the first thread trimmer 5. At the same time, the upper thread loop will approach the first constraint structure on the thread trimming catcher 7, and the second constraint structure will also approach the first constraint structure. Before the thread is engaged and trimmed, the second constraint structure cooperates with the first constraint structure to constrain the fabric edge thread 9a in the upper thread loop to a fixed thread trimming constraint position, and then the thread is engaged and the fabric edge thread 9a of the upper thread loop is cut at the first cutting edge 5a. Figure 13 and Figure 14 In the present invention, the fixed thread trimming restraint position means that it is fixed relative to the fixed first thread trimmer 5. The thread trimming restraint position can be a position within a certain range. Each time the thread is trimmed, the cloth edge line 9a will be located at this thread trimming restraint position. Therefore, each time the thread is trimmed, the cloth edge line 9a is restricted to a stable position, improving the stability of the upper thread loop during thread trimming, and making the length of the thread end of the thread 9 basically consistent after the thread is trimmed.

[0079] See also Figures 1 to 14 The following specific embodiment further illustrates the thread cutting mechanism of the present invention.

[0080] In the sewing machine, the axis of the rotary hook assembly 2 is along the left and right direction of the sewing machine, and the rotary hook assembly 2 is located on the left side of the sewing machine. Figure 3 、 Figure 5 and Figure 9As a preferred design, the thread cutting hook 6b of the second thread cutting knife 6 is composed of a hooking bevel 6c and a hooking rib 6d. The hooking bevel 6c extends obliquely to the right from the left side of the second thread cutting knife 6, and the hooking rib 6d is arranged on the right side of the hooking bevel 6c. A notch structure is formed between the hooking bevel 6c and the hooking rib 6d to form the thread cutting hook 6b; in addition to hooking the thread, the thread cutting hook 6b also constitutes a part of the second constraint structure; the thread cutting catcher 7 includes an arc-shaped catch piece 71 arranged along the outer peripheral side of the rotary hook assembly 2, and the arc-shaped catch piece 71 is arranged along the outer peripheral side of the rotary hook assembly 2. The plate 71 is located between the rotary hook assembly 2 and the first thread trimmer 5. The end of the arcuate catch plate 71 facing the second thread trimmer 6 is the A-side end 711, and the other end is the B-side end 712. In this embodiment, the first thread trimmer 5 and the second thread trimmer 6 are located at the front and rear sides of the sewing machine, respectively. When the thread trimmer catch member 7 is installed, the A-side end 711 of the arcuate catch plate 71 faces the rear side of the sewing machine, in which case the A-side end 711 is the front end, and the B-side end 712 of the arcuate catch plate 71 faces the front side, in which case the B-side end 712 is the rear end. The first restraint structure includes a restraint side edge 71a arranged to the right of the A-side end 711 of the arcuate catch plate 71 and inclined to the right. The restraint side edge 71a is opposite the thread trimmer hook 6b, and the side of the restraint side edge 71a near the A-side end 711 extends to the left of the hooking bevel 6c. With the above structure, when trimming the thread, the second thread trimmer 6 rotates toward the first thread trimmer 5, and the thread trimming hook 6b hooks the bottom thread 10 and the edge thread 9a in the upper thread loop. Since the restraining side 71a extends to the left side of the thread trimming hook 6b, the bottom thread 10 and the upper thread 9 will not appear on the left side of the arc-shaped catching piece 71, that is, they will not be wrapped around the arc-shaped catching piece 71, but will only be located on the right side of the restraining side 71a. Figure 12 Then the trimming hook 6b and the restraining side 71a meet to form a closed area, see Figure 9 That is, the hooking bevel 6c, the hooking retaining edge 6d and the restraining side edge 71a enclose a closed area. At this time, the bottom thread 10 and the selvedge thread 9a are both located in the closed area. In addition, during the rotation of the second thread trimmer 6, the closed area gradually becomes smaller, thereby restraining the selvedge thread 9a. Finally, when the second cutting edge 6a and the first cutting edge 5a are engaged, the selvedge thread 9a is stable. Figure 10 and Figure 11 In this embodiment, when the second blade 6a and the first blade 5a engage to cut the thread, there are two options. One option is that the closed area formed by the intersection of the cutting hook 6b and the restraining side 71a still exists. Figure 11, the enclosed area becomes a very narrow space, which can effectively restrain the selvage thread 9a and avoid the problem of breaking the selvage thread 9a at this location; the second solution is that the thread trimming hook 6b completely crosses the restraining side 71a, so that the enclosed area disappears. At this time, the selvage thread 9a will be tightened and restrained at the bottom of the thread trimming hook 6b, that is, the connection between the hook bevel 6c and the hook retaining edge 6d. This solution has the advantage of a more stable structure. Of course, in another embodiment, under appropriate circumstances, the first thread trimmer 5 and the second thread trimmer 6 can also be swapped in position, with the first thread trimmer 5 located at the rear side and the second thread trimmer 6 located at the front side. In this case, the side end A 711 is the rear side end and the side end B 712 is the front side end. The principle is the same, but the orientation is opposite, so it will not be repeated.

[0081] In this embodiment, see Figure 3 and Figure 9 As a preferred design, the thread-hooking retaining edge 6d of the thread trimmer hook 6b is tilted left and right, with the front end (the end closest to the thread trimmer catch 7) on the left and the rear end (the end away from the thread trimmer catch 7) on the right. In other words, the thread-hooking retaining edge 6d extends from the left front to the right rear, and the tilt angle of the thread-hooking retaining edge 6d is relatively small, ranging from 2 to 4 degrees relative to the front-to-back direction, with 3 degrees being preferred. With this slightly tilted thread-hooking retaining edge 6d, as the second thread trimmer 6 rotates, the closed area shrinks and its rightmost position gradually shifts to the right. In other words, the rightmost position that the bottom thread 10 and the edge thread 9a can reach within the closed area gradually shifts to the right.

[0082] In this embodiment, see Figure 3 、 Figure 9 and Figure 13 As a preferred design, the second thread trimmer 6 is provided with a dividing tip 6e for inserting into the upper thread loops to separate the threads. The left side of the dividing tip 6e is a thread hooking edge 6d, that is, the thread hooking edge 6d is shared with the thread trimmer hook 6b, and the right side of the dividing tip 6e has a first dividing bevel 6f tilted to the right. When the thread trimming action starts, the second thread trimmer 6 rotates, and the dividing tip 6e is inserted into the upper thread loop to preliminarily separate the upper thread loops, wherein the fabric edge thread 9a is located on the left side of the dividing tip 6e, that is, in the displacement thread trimmer hook 6b, and the needle edge thread 9b is located on the right side of the dividing tip 6e, and moves to the right along the first dividing bevel 6f when the second thread trimmer 6 rotates, thereby gradually separating the upper thread loops. For further information, see Figure 5 and Figure 9 The right side of the arc-shaped capture piece 71 is provided with a second dividing line bevel 71b opposite to the first dividing line bevel 6f. When the second thread trimmer 6 rotates toward the first thread trimmer 5, the first dividing line bevel 6f intersects with the second dividing line bevel 71b. The second dividing line bevel 71b will drive the needle edge line 9b to move along the first dividing line bevel 6f and constrain the needle edge line 9b at the intersection. Figure 13 At this time, the first dividing line bevel 6f constitutes part of the second constraint structure, and the second dividing line bevel 71b constitutes part of the first constraint structure, thereby better stabilizing the position of the upper thread loop. When the second blade 6a and the first blade 5a engage, the intersection of the first dividing line bevel 6f and the second dividing line bevel 71b remains stable each time the thread is trimmed, that is, the position of the needle edge thread 9b remains stable. Therefore, the shape and length of the upper thread loop are stable. After the thread is trimmed, the length of the upper thread 9 formed is stable. In addition, because the needle edge thread 9b moves a certain distance along the first dividing line bevel 6f, that is, the upper thread loop has a certain length, the upper thread 9 formed after the thread is trimmed has a certain length and will not be too short.

[0083] In this embodiment, see Figure 4 、 Figure 5 and Figure 7 As a preferred design, the first thread trimmer 5 is provided with a first catching portion 5b on the side facing the rotary hook assembly 2, and the outer arc surface of the arc-shaped catching piece 71 is provided with a second catching portion 71c that abuts against the first catching portion 5b; when trimming the thread, the second thread trimmer 6 rotates toward the first thread trimmer 5 and the thread trimmer hook 6b drives the bottom thread 10 into the space between the first catching portion 5b and the second catching portion 71c. The arc-shaped catching piece 71 is configured as an arc-shaped thin sheet structure, which can be easily installed in the narrow space there, especially the narrow space between the rotary hook assembly 2 and the first thread trimmer 5 (the gap is about 0.7mm). During normal operation, see Figure 3 The second thread trimmer 6 does not move and moves away from the first thread trimmer 5. At this time, the second catching portion 71c on the arc-shaped catching piece 71 abuts against the first catching portion 5b on the first thread trimmer 5, forming a bottom line catching structure. The rotary hook assembly 2 can rotate normally and work. When it is necessary to trim the thread, the second thread trimmer 6 rotates towards the first thread trimmer 5. The second thread trimmer 6 can first contact the first thread trimmer 5 and lift it up. Figure 4 The first catching part 5b and the second catching part 71c are separated, and the thread trimming hook 6b drives the bottom surface and the upper thread 9 into between the first catching part 5b and the second catching part 71c, and then continues to rotate until the second blade 6a and the first blade 5a bite and cut the thread. The bottom thread 10 and the edge thread 9a are cut in the opening of the opened bottom thread capturing structure. Figure 8 and Figure 13After the thread trimming is completed, the second thread trimmer 6 rotates and resets, leaving the first thread trimmer 5, and the first catching portion 5b and the second catching portion 71c are in contact again, capturing the thread ends of the bottom thread 10, thereby ensuring that the position of the thread ends of the bottom thread 10 after the thread trimming is stable. In the present application, when the thread ends of the bottom thread 10 are captured, the thread ends of the bottom thread 10 can be just clamped between the first catching portion 5b and the second catching portion 71c, or can be located near the first catching portion 5b and the second catching portion 71c, as long as the first thread trimmer 5 and the arc-shaped catching piece 71 can give the thread ends of the bottom thread 10 a certain clamping force so that the thread ends will not fall out.

[0084] After trimming is complete, see Figure 14 When the end of the bottom thread 10 is captured, it is located on the outer arc surface of the arc-shaped capturing piece 71, that is, on the upper side of the arc-shaped capturing piece 71. The bottom thread 10 extends from the hook inner liner 2a in the hook assembly 2 and then passes through the hook frame wire groove 2c to reach the outer arc surface of the arc-shaped capturing piece 71. After being captured by the bottom thread capturing structure, the position of the end of the bottom thread 10 can be guaranteed to be stable.

[0085] In this embodiment, further, see Figure 9 As a preferred design, the thread hooking rib 6d is located near one end of the thread trimming catch 7 and is located on the right side of the second catching portion 71c. Since the thread hooking rib 6d is tilted left and right, after the thread trimming is completed, when the second thread trimmer 6 rotates and retreats backward, the thread hooking rib 6d will gradually move the end of the bottom thread 10 to the left by a certain distance to ensure that the end of the bottom thread 10 is located between the second catching portion 71c and the first catching portion 5b, thereby ensuring that the end of the bottom thread 10 can be stably captured.

[0086] In the embodiment, as a preferred design, see Figure 3 、 Figure 4 and Figure 13 The first thread trimmer 5 is provided with a raised portion 5c, and the second thread trimmer 6 is provided with a raised portion 6g that is inclined toward the side where the rotary hook assembly 2 is located. That is, the raised portion 6g is tilted downward at a certain angle. When the second thread trimmer 6 rotates toward the first thread trimmer 5, the raised portion 6g first inserts under the lower side of the raised portion 5c. As the second thread trimmer 6 rotates, the raised portion 6g gradually raises the raised portion 5c. The raised portion 6g functions like a cam, separating the first thread trimmer 5 from the curved catch piece 71 by a certain distance, facilitating the insertion of the first thread trimmer 5. In other embodiments, if certain dimensions permit, when the second thread trimmer 6 enters between the curved catch piece 71 and the second thread trimmer 6, the second thread trimmer 6 can also press on the curved catch piece 71 to deform it downward.

[0087] In this embodiment, the thread trimming mechanism can be an improvement on the existing thread trimming mechanism, and a thread trimming catcher 7 is added to realize the upper thread 9 constraint and the lower thread 10 capture function, wherein the thread trimming mechanism can adopt a circular knife single-knife thread trimming mechanism. At this time, the first thread trimmer 5 and the second thread trimmer 6 are respectively the fixed knife and the movable knife in the circular knife single-knife thread trimming mechanism, and both are arc-shaped blades. The thread trimming mechanism can adopt a circular knife double-knife thread trimming mechanism. At this time, the first thread trimmer 5 and the second thread trimmer 6 are respectively the fixed knife and the auxiliary knife in the circular knife single-knife thread trimming mechanism, and both are arc-shaped blades.

[0088] In this embodiment, preferably, see Figure 5 An arc-shaped protrusion 71d is provided on the right side of the arc-shaped capturing piece 71, and the front end of the restraining side edge 71a (close to the B side end 712) extends all the way to the arc-shaped protrusion 71d, that is, the side of the arc-shaped protrusion 71d is a part of the restraining side edge 71a, and the first capturing portion 5b is provided on the outer arc surface of the arc-shaped protrusion 71d. With this design, on the one hand, the closed area formed by the intersection of the thread cutting hook 6b and the restraining side edge 71a will gradually become more slender as it gradually becomes smaller, see Figure 10 and Figure 12 , which can better constrain the position of the edge line 9a. On the other hand, the second capture portion 71c is closer to the hooking edge 6d, which can better capture the end of the bottom thread 10 after the thread trimming is completed. On the right side of the arc-shaped capture piece 71, the junction between the constraining side edge 71a and the second dividing line oblique edge 71b can also be concave. Figure 6 The second capturing portion 71c is provided near the inner concave-convex portion.

[0089] In the embodiment, as a preferred design, see Figure 5 , see Figure 6The thread trimming catcher 7 mainly includes two parts: an arc-shaped arc-shaped catch piece 71 and a mounting section 72 connected to the arc-shaped catch piece 71. The inner diameter of the arc-shaped catch piece 71 is slightly larger than the outer diameter of the shuttle skin 2b and is coaxially arranged to fit the outer shape of the rotary hook assembly 2 while leaving a gap. The outer diameter of the arc-shaped catch piece 71 is slightly smaller than the second thread trimmer 6 to match the second thread trimmer 6 and ensure that the second thread trimmer 6 can be smoothly inserted into the upper side of the arc-shaped catch piece 71 without interference when trimming the thread. The mounting section 72 is used for the fixed installation of the thread trimming catcher 7. In this application, the component used for the fixed installation of the thread trimming catcher 7 in the sewing machine is recorded as the catcher mounting base, and the mounting section 72 is fixedly connected to the catcher mounting base. Among them, the catcher mounting base can be a housing 1 or other fixed components. In this embodiment, the mounting section 72 is fixedly mounted to the catcher mounting base using a fastening screw 11. The mounting section 72 is provided with a strip-shaped connecting hole 72a extending in the front-to-back direction. The fastening screw 11 is threaded into the catcher mounting base through the strip-shaped connecting hole 72a. By tightening or loosening the fastening screw 11, the front-to-back position of the thread trimmer catcher 7 can be adjusted, facilitating assembly and providing more flexible coordination between the arcuate catcher 71 and the first and second thread trimmers 5 and 6. The mounting section 72 can specifically utilize the mounting position of the thread dividing piece 01 in existing sewing machines, minimizing modifications to the existing structure.

[0090] Furthermore, a tension adjustment hole (not shown in the accompanying drawings) can be provided on the mounting section 72. The tension adjustment hole is arranged on the side close to the arc-shaped capture piece 71, and is screwed into the capture piece mounting base by passing an adjustment screw through the tension adjustment hole. There is an adjustment gap between the tension adjustment hole and the capture piece mounting base. At this time, by tightening or loosening the adjustment screw, the mounting section 72 close to the arc-shaped capture piece 71 can be deformed to a certain extent, thereby changing the size of the adjustment gap between the tension adjustment hole and the capture piece mounting base, thereby changing the contact pressure between the second capture part 71c and the first capture part 5b, thereby changing the clamping force of the bottom line 10 thread end. It is flexible and convenient to use and can meet different needs.

[0091] Because the thread-catching member 7 in this application is located in the core area where the sewing machine's thread path is formed and its distance from the rotary hook assembly 2 and the first thread cutter 5 is extremely close, the outer edges of the entire part must be rounded, polished, and quenched to ensure its shape, toughness, strength, and burr-free edges. The curved catch piece 71 and mounting section 72 of the thread-catching member 7 are preferably integrally formed and can be manufactured using conventional sheet metal stamping, precision casting, lathe processing, or other modern parts processing techniques.

[0092] The present invention also provides a sewing machine, comprising a rotary hook mechanism and the above-mentioned thread trimming mechanism, wherein the thread trimming mechanism is arranged at the rotary hook assembly 2 in the rotary hook mechanism for thread trimming.

[0093] As can be seen from the above, the thread trimming mechanism in this embodiment has the following beneficial effects:

[0094] 1. By setting the first constraint structure and the second constraint structure, the upper thread loop is constrained at a fixed position during thread trimming, thereby improving the stability of the upper thread loop during thread trimming and making the length of the thread ends of the thread 9 basically consistent after thread trimming, thereby increasing the probability of forming a stitch with the lower thread 10 when starting to sew next time.

[0095] 2. While restraining the upper thread 9, the second catching portion 71c is provided on the arc-shaped catching piece 71, which forms a bobbin thread catching structure together with the first catching portion 5b of the first thread trimmer 5. This can stabilize the position of the bobbin thread 10, greatly improving the success rate of bringing the bobbin thread 10 and forming a lockstitch when starting the seam, solving the long-standing customer feedback problem of starting the seam with computerized thread trimmer sewing machines.

[0096] 3. The structure is simple, and it can be improved in the existing thread cutting mechanism, and the cost is low. In summary, the present invention effectively overcomes the various shortcomings of the existing technology and has high industrial utilization value.

[0097] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Anyone skilled in the art may 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 one of ordinary skill in the art without departing from the spirit and technical principles disclosed herein are intended to be covered by the claims of the present invention.

Claims

1. A thread trimming mechanism of a sewing machine, used for being arranged at a rotary hook assembly (2) of the sewing machine for thread trimming, wherein the rotary hook assembly (2) is positioned and installed by a rotary hook positioning hook (3), and the rotary hook positioning hook (3) is fixed in the sewing machine; the thread trimming mechanism comprises a first thread trimmer (5) and a second thread trimmer (6), wherein the first thread trimmer (5) is fixedly installed at the outer peripheral side of the rotary hook assembly (2), and the second thread trimmer (6) is arranged at the outer peripheral side of the rotary hook assembly (2) and can rotate around the rotary hook assembly (2) to engage with or separate from the first thread trimmer (5), and the second thread trimmer (6) is provided with a thread trimmer hook (6b) for hooking the bottom thread (10) and the top thread (9) toward the first thread trimmer (5), characterized in that: The thread trimming mechanism further comprises a fixedly mounted thread trimming catcher (7), the thread trimming catcher (7) being provided with a first constraint structure, and the second thread trimmer (6) being provided with a second constraint structure; when thread trimming begins, the second thread trimmer (6) rotates toward the first thread trimmer (5) and the thread trimming hook (6b) drives the upper thread (9) close to the first constraint structure, and before the second thread trimmer (6) and the first thread trimmer (5) engage and trim the thread, the second constraint structure cooperates with the first constraint structure and constrains the edge of the upper thread loop to a fixed thread trimming constraint position; the thread trimming hook (6b) of the second thread trimmer (6) is composed of a thread hooking oblique edge (6c) and a thread hooking retaining edge (6d), the thread hooking oblique edge (6c) extending obliquely to the right from the left side of the second thread trimmer (6), the thread hooking retaining edge (6d) being arranged on the right side of the thread hooking oblique edge (6c), and the second constraint structure comprising The thread trimming hook (6b) is provided. The thread trimming catcher (7) comprises an arc-shaped catch piece (71) arranged along the outer peripheral side of the rotary hook assembly (2), and the arc-shaped catch piece (71) is located between the rotary hook assembly (2) and the first thread trimmer (5). One end of the arc-shaped catch piece (71) facing the second thread trimmer (6) is the A side end (711), and the other end is the B side end (712). The first constraint structure comprises a constraint side edge (71a) arranged on the right side of the A side end (711) of the arc-shaped catch piece (71) and inclined to the right. The constraint side edge (71a) is opposite to the thread trimming hook (6b), and the side of the constraint side edge (71a) close to the A side end (711) extends to the left side of the hook oblique edge (6c). When the second thread trimmer (6) rotates toward the first thread trimmer (5), the thread trimming hook (6b) and the constraint side edge (71a) intersect to form a closed area.

2. The thread trimming mechanism according to claim 1, characterized in that: When the second thread cutter (6) rotates to engage with the first thread cutter (5) to cut the thread, the closed area formed by the intersection of the thread cutter hook (6b) and the restraining side (71a) still exists.

3. The thread trimming mechanism according to claim 1, characterized in that: When the second thread cutter (6) rotates to engage with the first thread cutter (5) to cut the thread, the thread cutter hook (6b) crosses the restraining side edge (71a) so that the closed area disappears.

4. The thread trimming mechanism according to claim 1, characterized in that: The thread hooking retaining edge (6d) is arranged to be tilted left and right, with the end close to the thread trimming catch member (7) located on the left side and the end away from the thread trimming catch member (7) located on the right side.

5. The thread trimming mechanism according to claim 1, characterized in that: The second thread cutter (6) is provided with a thread dividing tip (6e) for inserting between the surface thread loops to divide the thread, the left side of the thread dividing tip (6e) is a thread hooking retaining edge (6d), and the right side of the thread dividing tip (6e) has a first thread dividing oblique edge (6f) inclined to the right.

6. The thread trimming mechanism according to claim 5, characterized in that: The right side of the arc-shaped capture piece (71) is provided with a second dividing line bevel (71b) opposite to the first dividing line bevel (6f); when the second thread cutter (6) rotates toward the first thread cutter (5), the first dividing line bevel (6f) and the second dividing line bevel (71b) intersect; the second constraint structure also includes the first dividing line bevel (6f), and the first constraint structure also includes the second dividing line bevel (71b).

7. The thread trimming mechanism according to claim 1, characterized in that: An arc-shaped protrusion (71d) is provided on the right side of the arc-shaped capturing piece (71), and the arc-shaped protrusion (71d) is located on the left side of the hook line retaining edge (6d), and the end of the restraining side edge (71a) close to the B side end (712) extends to the arc-shaped protrusion (71d).

8. The thread trimming mechanism according to claim 1, characterized in that: The first thread cutter (5) is provided with a first catching portion (5b) on the side facing the rotary hook assembly (2), and the outer arc surface of the arc-shaped catching piece (71) is provided with a second catching portion (71c) abutting against the first catching portion (5b); when cutting the thread, the second thread cutter (6) rotates toward the first thread cutter (5) and causes the thread cutting hook (6b) to drive the bottom thread (10) to extend between the first catching portion (5b) and the second catching portion (71c).

9. The thread trimming mechanism according to claim 8, characterized in that: The thread hooking retaining edge (6d) is tilted left and right, with one end close to the thread trimming catch member (7) located on the left and one end away from the thread trimming catch member (7) located on the right. The end of the thread hooking retaining edge (6d) close to the thread trimming catch member (7) is located on the right side of the second catching portion (71c).

10. The thread trimming mechanism according to claim 9, characterized in that: The hook line retaining edge (6d) has an inclination angle of 2 to 4 degrees relative to the front-back direction.

11. The thread trimming mechanism according to claim 10, characterized in that: The hook line retaining edge (6d) has an inclination angle of 3° relative to the front-rear direction.

12. The thread trimming mechanism according to claim 8, characterized in that: The first thread cutter (5) is provided with a raised portion (5c), and the second thread cutter (6) is provided with a raised portion (6g) inclined toward the side where the rotary hook assembly (2) is located. When the second thread cutter (6) rotates toward the first thread cutter (5), the raised portion (6g) is inserted into the lower side of the raised portion (5c) facing the rotary hook assembly (2).

13. The thread trimming mechanism according to claim 1 or 8, characterized in that: The thread trimmer catch member (7) has a mounting section (72) connected to the arc-shaped catch piece (71); a component in the sewing machine used for fixedly mounting the thread trimmer catch member (7) is a catch member mounting base; and the mounting section (72) is fixedly connected to the catch member mounting base.

14. The thread trimming mechanism according to claim 13, characterized in that: The mounting section (72) is fixedly mounted on the capture member mounting base by means of a fastening screw (11); a strip-shaped connecting hole (72a) extending in a front-to-rear direction is provided on the mounting section (72); the fastening screw (11) passes through the strip-shaped connecting hole (72a) and is screwed into the capture member mounting base.

15. A sewing machine comprising a rotary hook assembly (2), characterized in that: It also includes a thread cutting mechanism according to any one of claims 1 to 14, wherein the thread cutting mechanism is arranged at the rotary hook assembly (2) to cut the thread.

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