A double blade thread trimming mechanism of a sewing machine, and a sewing machine

Abstract

This invention relates to a double-blade thread-cutting mechanism for a sewing machine, and the sewing machine itself. The double-blade thread-cutting mechanism includes a first blade holder, a first thread-cutting blade, a second blade holder, a second thread-cutting blade, and a thread-cutting drive mechanism. It also includes a bobbin thread catcher, which includes an mounting section and an arc-shaped catcher plate. One end of the arc-shaped catcher plate is connected to the mounting section (B-side end), and the other end facing the second thread-cutting blade is also a B-side end. The first thread-cutting blade has a first catcher portion, and the outer arc surface of the arc-shaped catcher plate has a second catcher portion. In the initial position, the first catcher portion and the second catcher portion abut against each other. A drive pressure block is also fixed on the first blade holder or the first thread-cutting blade. During thread cutting, the second thread-cutting blade and the first thread-cutting blade rotate to approach each other, and the drive pressure block presses the arc-shaped catcher plate to bend or deflect towards the rotary hook assembly until it separates from the first thread-cutting blade, and the thread-cutting hook extends between the first catcher portion and the second catcher portion. The arc-shaped catcher plate returns to its original position when it is no longer squeezed by the drive pressure block.

Description

Technical Field

[0001] This invention relates to the field of sewing equipment, specifically to a double-blade thread-cutting mechanism for a sewing machine, and a sewing machine. Background Technology

[0002] Catching the bobbin thread after trimming can greatly improve the success rate of starting a sewing machine with the bobbin thread. However, for many years, flatbed sewing machines using a circular blade thread trimming mechanism have had a no-go zone for bobbin thread catching, lacking an effective way to achieve this.

[0003] Flatbed thread cutting mechanisms are further divided into single-blade and double-blade types. In a single-blade mechanism, the fixed blade, mounted behind the needle, is a stationary thread cutter, while the moving blade is a movable thread cutter. During cutting, the moving blade rotates towards the fixed blade, completing the cut on the side of the needle closest to the operator (also known as the front of the sewing machine). The problem is that the sharp edge of the fixed blade, even slightly close to the area where the needle and thread move, increases the thread breakage rate during sewing. Therefore, the fixed blade cannot be installed below the needle to achieve a shorter thread end on the fabric after cutting. A double-blade thread cutting mechanism uses a pair of bidirectional moving thread cutters, allowing cutting directly below the needle. After cutting, the blades move away from the area where the needle and thread move. It has the advantage of leaving a shorter thread end on the fabric after cutting compared to a single-blade mechanism, better meeting the production and quality requirements of high-end garments, and thus gaining market acceptance.

[0004] Therefore, providing a double-blade thread-cutting mechanism capable of capturing the bottom line is a problem that urgently needs to be solved in sewing machines. Summary of the Invention

[0005] 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 double-blade thread cutting mechanism for a sewing machine, and a sewing machine that can stabilize the position of the bottom thread end after thread cutting to ensure smooth start of the next sewing, thus solving the problem of difficulty in starting sewing in the existing double-blade thread cutting mechanism; moreover, the structure is extremely simple, requiring only modification of the existing double-blade thread cutting mechanism.

[0006] To achieve the above objectives, the present invention provides a double-blade thread-cutting mechanism for a sewing machine, used for cutting thread at the rotary hook assembly of the sewing machine. The double-blade thread-cutting mechanism includes a first blade holder, a first thread-cutting blade fixed to the first blade holder, a second blade holder, a second thread-cutting blade fixed to the second blade holder, and a thread-cutting drive mechanism. The first and second thread-cutting blades are located on the outer periphery of the rotary hook assembly. The thread-cutting drive mechanism drives the first blade holder and the second thread-cutting blade to rotate, causing the first and second thread-cutting blades to rotate around the axis of the rotary hook assembly until they approach or separate. The second thread-cutting blade is provided with a thread-cutting hook for driving the bobbin thread towards the first thread-cutting blade. The double-blade thread-cutting mechanism also includes a bobbin thread catcher, which includes a fixedly installed mounting section and an arc-shaped catcher plate connected to the mounting section. The arc-shaped catcher plate is distributed along the outer periphery of the rotary hook assembly. The arc-shaped capture plate is positioned within the minimum rotation range of the first wire cutter. One end of the arc-shaped capture plate is connected to the mounting section as side B, and the other end facing the second wire cutter is side B. The first wire cutter has a first capture part on its side facing the rotary hook assembly, and a second capture part is provided on the outer arc surface of the arc-shaped capture plate. When the first wire cutter is not cutting the wire, the first capture part and the second capture part abut against each other. A driving pressure block is also fixed on the first blade holder or the first wire cutter. The driving pressure block is located on the outer arc surface of the arc-shaped capture plate. When cutting the wire, both the second wire cutter and the first wire cutter rotate to approach each other, and the driving pressure block moves on the outer arc surface of the arc-shaped capture plate and presses the arc-shaped capture plate to bend or deflect towards the rotary hook assembly until it separates from the first wire cutter. The wire cutting hook extends between the first capture part and the second capture part. The arc-shaped capture plate can return to its original position when it is not squeezed by the driving pressure block.

[0007] Furthermore, the distance between the B-side end of the arc-shaped capture plate and the rotary shuttle assembly is smaller than the distance between the A-side end and the rotary shuttle assembly.

[0008] Furthermore, the outer arc surface of the arc-shaped capture piece is provided with a protrusion, and when the wire is cut, the driving pressure block will move on the protrusion on the outer arc surface of the arc-shaped capture piece.

[0009] Furthermore, the driving block has a smooth working surface for contacting the outer arc surface of the arc-shaped capture plate.

[0010] Furthermore, the mounting section of the bottom line capturing component is fixedly connected to the arc-shaped capturing plate, and the arc-shaped capturing plate itself can be bent and deformed.

[0011] Furthermore, the mounting section of the bottom line capture component and the arc-shaped capture plate are rotatably connected, and an elastic reset structure is provided between the arc-shaped capture plate and the mounting section. When the arc-shaped capture plate deflects toward the rotary shuttle assembly, the elastic reset structure is in an elastic energy storage state and provides an elastic force to reset the arc-shaped capture plate.

[0012] Furthermore, the A-side end of the arc-shaped capture plate is chamfered to form an anti-collision notch.

[0013] Furthermore, the second wire cutter is arc-shaped and coaxial with the rotary hook assembly.

[0014] Furthermore, the first wire cutter has a first cutting edge on the side facing the second wire cutter, and the second wire cutter has a bulge with a through hole. The edge of the bulge at the through hole forms a second cutting edge. When cutting the wire, the first and second wire cutters come together until the first and second cutting edges engage.

[0015] Furthermore, it also includes an adjusting screw. The mounting section of the bobbin catcher is a flat plate structure, and the mounting section has a tension adjustment hole on the side near the arc-shaped catcher piece. The component in the sewing machine used for fixing the bobbin catcher is the catcher mounting base. The adjusting screw passes through the tension adjustment hole and is screwed into the catcher mounting base. There is an adjustment gap between the tension adjustment hole and the catcher mounting base. When the adjusting screw is tightened or loosened, it can cause the mounting section to deform and change the contact pressure between the second catcher and the first catcher.

[0016] Furthermore, the wire-cutting hook of the second wire cutter is composed of a hooking bevel and a hooking stop. The hooking bevel extends obliquely to the right from the left side of the second wire cutter, and the hooking stop is located on the right side of the hooking bevel. The hooking stop is obliquely arranged to the left and right, with the end closer to the bottom line capture member located on the left and the end farther from the bottom line capture member located on the right. The end of the hooking stop closer to the bottom line capture member is located on the right side of the second capture part.

[0017] Furthermore, the inclination angle of the hook-line stop relative to the front-back direction is 2-4°.

[0018] Furthermore, the angle of inclination of the hook-line guard relative to the front and rear directions is 3°.

[0019] The present invention also provides a sewing machine, including a rotary hook mechanism and the aforementioned double-blade thread cutting mechanism, wherein the double-blade thread cutting mechanism is disposed at the rotary hook assembly in the rotary hook mechanism to cut the thread.

[0020] As described above, the double-blade thread-cutting mechanism and sewing machine of the present invention have the following beneficial effects:

[0021] By setting up a bottom thread catcher, the second catcher on the arc-shaped catcher plate and the first catcher on the first thread cutter form a bottom thread catcher structure. During thread cutting, both the first and second thread cutters rotate around the axis of the rotary hook assembly until they come close together. At the same time, the driving pressure block will squeeze the arc-shaped catcher plate during rotation, causing it to bend inward and separate from the first thread cutter. The first and second catcher parts separate, and the A-side end is located within the rotation range of the front part of the second thread cutter. The thread cutting hook will drive the bottom and top threads to extend between the first and second catcher parts. Then, the second and first thread cutters bite and cut the thread. The bottom and top threads are cut within the opening of the bottom thread catcher structure. After the thread cutting is completed, both the first and second thread cutters rotate and reset. At the same time, the arc-shaped catcher plate resets, and the first catcher parts reset to contact each other again, capturing the bottom thread end and ensuring the bottom thread end is in a stable position. The double-blade thread cutting mechanism of this invention can stabilize the position of the bottom thread end after cutting, ensuring a smooth start to the next stitch, improving the stability of sewing performance, and solving the problem of difficulty in starting stitches in existing double-blade thread cutting mechanisms. Furthermore, the double-blade thread cutting mechanism has an extremely simple structure, requiring only a modification to existing double-blade thread cutting mechanisms. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of a first embodiment of the double-blade wire-cutting mechanism of the present invention.

[0023] Figure 2 for Figure 1 Exploded view.

[0024] Figure 3 This is a schematic diagram of the bottom line capture device in Embodiment 1 of the present invention.

[0025] Figure 4 This is a schematic diagram of the anti-collision notch on the bottom line capture component in Embodiment 1 of the present invention.

[0026] Figure 5 This is a schematic diagram of the structure of the first wire cutter in Embodiment 1 of the present invention.

[0027] Figure 6 This is a schematic diagram of the structure of the second wire cutter in Embodiment 1 of the present invention.

[0028] Figure 7 This is a schematic diagram of the structure of the first tool holder in Embodiment 1 of the present invention.

[0029] Figure 8 This is a schematic diagram of the structure of the second tool holder in Embodiment 1 of the present invention.

[0030] Figure 9 This is a schematic diagram of the double-blade wire-cutting mechanism in the initial position according to Embodiment 1 of the present invention.

[0031] Figure 10 This is a schematic diagram of the double-blade wire-cutting mechanism in Embodiment 1 of the present invention after the wire cutting begins.

[0032] Figure 11 This is a schematic diagram of the double-blade wire cutting mechanism in Embodiment 1 of the present invention when the arc-shaped capturing plate separates from the first wire cutting blade after the wire cutting begins.

[0033] Figure 12 This is a schematic diagram of the double-blade wire cutting mechanism in Embodiment 1 of the present invention during the biting and cutting of wire.

[0034] Figure 13 This is a schematic diagram of the double-blade wire-cutting mechanism in Embodiment 1 of the present invention retracting and resetting after wire cutting is completed.

[0035] Figure 14 This is a schematic diagram of the bottom line capture device in Embodiment 2 of the present invention.

[0036] Figure 15 This is a right-side view of the baseline capture component in Embodiment 2 of the present invention.

[0037] Figure 16 This is a front view of the baseline capture component in Embodiment 2 of the present invention.

[0038] Explanation of icon numbers

[0039] 1. Bottom-line capture component

[0040] 101 Arc-shaped Capture Plate

[0041] 102 Installation Section

[0042] 103 Second Capture Section

[0043] 104 B side end

[0044] 105 A side end

[0045] 106 anti-collision gaps

[0046] 107 Protrusions

[0047] 2 First Thread Cutter

[0048] 201 First Capture Division

[0049] 202 First Installation Department

[0050] 203 Wire Cutting Workboard

[0051] 3 Second wire cutter

[0052] 301 bulge

[0053] 302 Wire Cutting Hook

[0054] 303 Hypothesis of the dividing line

[0055] 304 Second Installation Department

[0056] 305 Hook line bevel

[0057] 306 hook-and-line edge protection

[0058] 4 First tool holder

[0059] 401 First Mounting Plate

[0060] 402 Drive Block

[0061] 403 Drive Connection Pin

[0062] 404 mounting threaded hole

[0063] 5 Second tool holder

[0064] 501 Second Mounting Plate

[0065] 502 drive connection hole

[0066] 6. Rotary Shuttle Assembly

[0067] A. Minimum rotation range of the second wire cutter

[0068] B. Direction of rotation when the second wire cutter cuts the wire.

[0069] C. Direction of rotation when the first wire cutter cuts the thread. Detailed Implementation

[0070] 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.

[0071] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings of this specification are merely for illustrative purposes to aid those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to the size, without affecting the effects and objectives achieved by the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and are 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.

[0072] See Figures 1 to 13This invention provides a double-blade thread-cutting mechanism for a sewing machine, used for cutting thread at the rotary hook assembly 6 of the sewing machine. The rotary hook assembly 6 is located on the left side of the sewing machine, which is existing technology. The double-blade thread-cutting mechanism of this invention includes a first blade holder 4, a first thread-cutting blade 2 fixed on the first blade holder 4, a second blade holder 5, a second thread-cutting blade 3 fixed on the second blade holder 5, and a thread-cutting drive mechanism. The first thread-cutting blade 2 and the second thread-cutting blade 3 are located on the outer periphery of the rotary hook assembly 6. The thread-cutting drive mechanism drives the first blade holder 4 and the second blade holder 5 to rotate, causing the first thread-cutting blade 2 and the second thread-cutting blade 3 to rotate around the axis of the rotary hook assembly 6 until they are close together or separated. The second thread-cutting blade 3 is provided with a thread-cutting hook 302 for driving the bobbin thread towards the first thread-cutting blade 2. See [link to relevant documentation]. Figure 1 , Figure 2 and Figure 9 The first thread cutter 2 and the second thread cutter 3 are both located on the upper side of the rotary hook assembly 6 with a certain gap. When the rotary hook assembly 6 rotates, it will not touch the first thread cutter 2 and the second thread cutter 3, and vice versa. The thread cutting drive mechanism drives the first blade holder 4 and the second blade holder 5 to rotate around the axis of the rotary hook assembly 6, thereby causing the first thread cutter 2 and the second thread cutter 3 to rotate around the axis of the rotary hook assembly 6. The second thread cutter 3 is equipped with a thread-cutting hook 302 for driving the bottom thread towards the first thread cutter 2. During thread cutting, the first thread cutter 2 and the second thread cutter 3 approach each other, and the thread-cutting hook 302 pushes both the bottom and top threads until they meet with the first thread cutter 2. The thread-cutting hook 302 enters the inner side of the first thread cutter 2, and finally, the second thread cutter 3 engages with the first thread cutter 2, cutting the bottom and top threads. In other words, the second thread cutter 3 is within the minimum rotation range of the first thread cutter 2.

[0073] The double-blade wire-cutting mechanism of the present invention also includes a bottom thread catcher 1, see [link / reference]. Figure 1 , Figure 2 , Figure 3 and Figure 9The thread catcher 1 includes a fixed mounting section 102 and an arc-shaped catcher piece 101 connected to the mounting section 102. Specifically, the mounting section 102 can be installed on a fixed structure attached to the rotary hook assembly 6 of the sewing machine. The arc-shaped catcher piece 101 is arranged along the outer periphery of the rotary hook assembly 6 and is located within the minimum rotation range of the first thread cutter 2. The minimum rotation range of the first thread cutter 2 is the range formed when rotating up to the innermost part of the first thread cutter 2 (the side facing the rotary hook assembly 6). One end of the arc-shaped catcher piece 101 connected to the mounting section 102 is the B-side end 104, and the other end facing the second thread cutter 3 is the A-side end 105. The first thread cutter 2 has a first catcher part 201 on its side facing the rotary hook assembly 6, and a second catcher part 103 is provided on the outer arc surface (the arc surface facing the first thread cutter 2) of the arc-shaped catcher piece 101. The first thread cutter 2 is located at the uncut... At the initial position of the line, the first capturing part 201 and the second capturing part 103 are in contact; a driving pressure block 402 is also fixed on the first blade holder 4 or the first wire cutter 2, and the driving pressure block 402 is located on the outer arc surface side of the arc-shaped capturing piece 101; when cutting the line, the second wire cutter 3 and the first wire cutter 2 both rotate to approach each other, and the driving pressure block 402 moves on the outer arc surface of the arc-shaped capturing piece 101 and presses the arc-shaped capturing piece 101 to bend or deflect towards the rotary shuttle assembly 6 to separate from the first wire cutter 2, and the wire cutting hook 302 extends into the space between the first capturing part 201 and the second capturing part 103; the arc-shaped capturing piece 101 can be reset when it is not squeezed by the driving pressure block 402.

[0074] The basic working principle of the double-blade wire-cutting mechanism involved in this invention is as follows: See Figure 3 In Figure 3 (A) and Figure 3 (B) The arc-shaped capturing piece 101 of the thread catcher 1 is configured as an arc-shaped thin sheet structure, which facilitates installation in confined spaces, especially in the narrow space between the rotary hook assembly 6 and the first thread cutter 2. When the sewing machine is working normally and the thread is not being cut, see [reference needed]. Figure 9 The first wire cutter 2 and the second wire cutter 3 are in their initial positions, separated. At this time, the second capturing part 103 on the arc-shaped capturing plate 101 abuts against the first capturing part 201 on the first wire cutter 2, forming a bottom line capturing structure. The driving pressure block 402 approaches the B-side end 104 of the arc-shaped capturing plate 101 and contacts or has a small gap with the outer arc surface, allowing the rotary hook assembly 6 to rotate normally. When the wire cutting operation begins, the wire cutting drive mechanism drives the first blade holder 4 and the second blade holder 5 to rotate, which in turn drives the first wire cutter 2 and the second wire cutter 3 to rotate around the axis of the rotary hook assembly 6. See [link to relevant documentation]. Figure 9 and Figure 10 , Figure 9Arrow B indicates the rotation direction of the first wire cutter 2, and arrow C indicates the rotation direction of the second wire cutter 3. During rotation, the driving pressure block 402 squeezes the arc-shaped capture piece 101, causing it to bend inwards (towards the location of the rotary hook assembly 6). The arc-shaped capture piece 101 separates from the first wire cutter 2, and side A 105 is within the rotation range of the front part of the second wire cutter 3 (the part that mates with the first wire cutter 2). See [reference needed]. Figure 10 and Figure 11 In this way, the second thread cutter 3 can be smoothly inserted between the arc-shaped capture plate 101 and the first thread cutter 2. The thread cutting hook 302 will drive the bottom thread and the top thread to extend between the first capture part 201 and the second capture part 103. Then, the second thread cutter 3 and the first thread cutter 2 engage to cut the thread. See below. Figure 12 After the thread is cut, the first thread cutter 2, the second thread cutter 3, and the drive pressure block 402 all retract and reset. The second thread cutter 3 moves away from the first thread cutter 2 and the arc-shaped capture piece 101. At the same time, the arc-shaped capture piece 101 resets elastically, and the first capture part 201 and the second capture part 103 re-engage, capturing the bottom thread end. This ensures that the bottom thread end is in a stable position after cutting. In this application, when capturing the bottom thread end, the bottom thread end can be sandwiched between the first capture part 201 and the second capture part 103, or it can be located near the abutting first capture part 201 and the second capture part 103. As long as the first thread cutter 2 and the arc-shaped capture piece 101 can provide a certain clamping force to the bottom thread end so that the thread does not come off. Furthermore, when the bobbin thread is captured, it is located on the outer arc surface of the arc-shaped capture plate 101, that is, on the upper side of the arc-shaped capture plate 101. The section of the bobbin thread extending from the front side of the rotary hook assembly 6 to the end of the thread forms an upwardly arched curved section. This curved section is outside the rotation range of the rotary hook assembly 6, so the rotary hook assembly 6 will not collide with this curved section when rotating, thus preventing erratic movement and ensuring the stability of the bobbin thread position. When sewing begins again, the captured bobbin thread and the top thread loop form a locking stitch. After the bobbin thread is released, the first capture part 201 and the second capture part 103 constitute the bobbin thread capture structure, entering the preparation state for the next bobbin thread capture.

[0075] The double-blade thread cutting mechanism of this invention can stabilize the position of the bobbin thread end after cutting, preventing it from being affected by the rotary hook and ensuring smooth start-up of the next stitch. This improves the stability of sewing performance and solves the problem of difficult start-up in existing double-blade thread cutting mechanisms. Furthermore, the double-blade thread cutting mechanism has an extremely simple structure, requiring only minor modifications to existing mechanisms. A small change is made to the thread divider in the existing mechanism, optimizing its curved bending portion to obtain the bobbin thread catcher 1, and a driving pressure block 402 is added to open and close the bobbin thread catcher structure.

[0076] See Figures 1 to 16The double-blade wire-cutting mechanism of the present invention will be further described below with two specific embodiments:

[0077] Example 1:

[0078] See Figures 1 to 13 This is a schematic diagram of the structure of Embodiment 1. In this embodiment, see... Figure 1 and Figure 2 The axis of the rotary hook assembly 6 is along the left-right direction of the sewing machine, and the rotary hook assembly 6 is located on the left side of the sewing machine. The first thread cutter 2 and the second thread cutter 3 are located on the front (operator's side) and rear side of the sewing machine, respectively. When the bobbin thread catcher 1 is installed, the A-side end 105 of the arc-shaped catcher 101 faces the rear of the sewing machine, and the B-side end 104 of the arc-shaped catcher 101 faces the front. Of course, in other embodiments, under appropriate circumstances, the positions of the first thread cutter 2 and the second thread cutter 3 can also be interchanged, with the first thread cutter 2 located on the rear side and the second thread cutter 3 located on the front side, with the same principle.

[0079] In this embodiment, see Figure 9 and Figure 10 The distance between the B-side end 104 of the arc-shaped capture plate 101 and the rotary shuttle assembly 6 is smaller than the distance between the A-side end 105 and the rotary shuttle assembly 6. That is, the B-side end 104 is closer to the rotary shuttle assembly 6. When the wire cutting operation begins, the wire cutting drive mechanism drives the first knife holder 4 and the second knife holder 5 to rotate, which in turn drives the first wire cutting knife 2 and the second wire cutting knife 3 to rotate around the axis of the rotary shuttle assembly 6. Since the distance between the B-side end 104 of the arc-shaped capture plate 101 and the rotary shuttle assembly 6 is smaller than the distance between the A-side end 105 and the rotary shuttle assembly 6, the drive pressure block 402 will squeeze the arc-shaped capture plate 101 during the rotation process, that is, when it moves from the B-side end 104 to the A-side end 105, causing it to bend inward (towards where the rotary shuttle assembly 6 is located), thereby separating the arc-shaped capture plate 101 from the first wire cutting knife 2.

[0080] See Figure 7 In Figure 7 (A) and Figure 7(B) In this embodiment, the first tool holder 4 is provided with a first mounting plate 401 and a drive connecting pin 403. The drive connecting pin 403 is used to connect with the wire cutting drive mechanism. The first mounting plate 401 is used for the fixed installation of the first wire cutting blade 2. It is provided with a mating surface and a mounting threaded hole 404. During installation, the mating surface is mated with the mating surface of the first wire cutting blade and fixed with screws. There is an extended part on the left side of the first mounting plate 401, which constitutes a drive pressure block 402. Of course, the drive pressure block 402 can also be installed on the first tool holder 4 by welding or other fixed connection methods. As a preferred design, the driving block 402 has a smooth working surface 402a on the side facing the arc-shaped capture plate 101. The smooth working surface 402a consists of arc-shaped surfaces on both sides and a flat surface in the middle, with a smooth transition at the joint. The smooth working surface 402a is used for the arc-shaped working surface that contacts the outer arc surface of the arc-shaped capture plate 101, so that the driving block 402 has low friction and moves more smoothly when it moves on the outer arc surface of the arc-shaped capture plate 101. Of course, in other embodiments, the driving block 402 can also be formed by a part of the first wire cutter 2, or fixedly connected to the first wire cutter 2.

[0081] In this embodiment, see Figure 4 As a preferred design, the mounting section 102 and the arc-shaped capture piece 101 of the bottom line catcher 1 are fixedly connected, and preferably are an integral structure, that is, the bottom line catcher 1 is an integral thin sheet structure processed in one piece, and the arc-shaped capture piece 101 itself can be bent and deformed. Of course, the mounting section 102 and the arc-shaped capture piece 101 can also be two independent structures, fixedly connected by welding or other methods. In this invention, the mounting section 102 and the arc-shaped capture piece 101 can also be rotatably connected, such as by material hinge or hinge connection, and the arc-shaped capture piece 101 can rotate around the connection point. An elastic reset structure is provided between the arc-shaped capture piece 101 and the mounting section 102, for example, a retaining spring can be provided. The two ends of the retaining spring are respectively connected to the arc-shaped capture piece 101 and the mounting section 102. When the arc-shaped capture piece 101 is compressed and deflects towards the rotary shuttle assembly 6, and the elastic reset structure is in an elastic energy storage state, it provides an elastic force to reset the arc-shaped capture piece 101. At this time, the bottom line catcher 1 can have bending ability or not.

[0082] In this embodiment, see Figure 5 In Figure 5 (A) Figure 5 (B) and Figure 5 (C) As a preferred design, the first wire cutter 2 includes a first mounting part 202 and a wire cutting work plate 203, see [link]. Figure 1 and Figure 2The first mounting part 202 is used to connect with the first knife holder 4. A portion of the inner side of the wire cutting working plate 203 constitutes the first capturing part 201. The side of the wire cutting working plate 203 facing the second wire cutting knife 3 is provided with a first cutting edge, which is used to engage with the second cutting edge on the second wire cutting knife 3.

[0083] In this embodiment, see Figure 6 In Figure 6 (A) Figure 6 (B) and Figure 6 (C) As a preferred design, the second wire cutter 3 is arc-shaped and coaxial with the rotary hook assembly 6. The position of the inner arc surface of the second wire cutter 3 constitutes its lowest rotation range, such as... Figure 6 (C) Within the range shown by arc A, the outer arc surface represents its maximum rotation range. A second wire cutter 3 with an arc shape is used, suitable for compact installation spaces in the wire cutting mechanism. The second wire cutter 3 includes an arc-shaped second mounting portion 304 with a connecting hole. See also... Figure 8 The second blade holder 5 includes an arc-shaped second mounting plate 501. The second mounting part 304 of the second wire cutter 3 is mounted on the second mounting plate 501 by screws, maintaining a close fit. The second blade holder 5 is also provided with a drive connection hole 502 for hinged connection with the wire cutting drive mechanism.

[0084] Preferably, in this embodiment, the second wire cutter 3 is provided with a bulge 301, and the bulge 301 is provided with a through hole. The edge of the bulge 301 at the through hole forms a second cutting edge. When cutting the wire, during the process of the first wire cutter 2 and the second wire cutter 3 approaching and converging, the first cutting edge of the first wire cutter 2 moves to the bulge 301 and is lifted a certain distance away from the rotation center. At this time, the first capturing part 201 of the first wire cutter 2 further opens, and then the first cutting edge and the second cutting edge bite together, and in this way the two wire cutters have a better biting force.

[0085] In this embodiment, see Figure 1 , Figure 2 and Figure 6As a preferred design, the wire-cutting hook 302 of the second wire cutter 3 is composed of a hooking bevel 305 and a hooking stop 306. The hooking bevel 305 extends obliquely to the right from the left side of the second wire cutter 3, and the hooking stop 306 is located to the right of the hooking bevel 305. A notch structure is formed between the hooking bevel 305 and the hooking stop 306, thus forming the wire-cutting hook 302. Preferably, the hooking stop 306 of the wire-cutting hook 302 is obliquely arranged to the left and right, with the front end (the end closer to the bottom thread catcher 1) located on the left and the rear end (the end farther from the bottom thread catcher 1) located on the right. That is, the hooking stop 306 extends from the front left to the rear right, and the end of the hooking stop 306 closer to the bottom thread catcher 1 is located on the right side of the second catching part 103. The inclination angle of the hooking stop 306 is small. Preferably, the inclination angle of the hooking stop 306 relative to the front-rear direction is selected as 2 to 4°, and 3° is preferred. Since the hook edge 306 is set to be tilted left and right, after the thread is cut, during the process of the second thread cutter 3 rotating and retracting to the rear, the hook edge 306 will gradually push the bottom thread end to the left a certain distance to ensure that the bottom thread end will be located between the second capturing part 103 and the first capturing part 201, thereby ensuring that the bottom thread end can be stably captured.

[0086] In this embodiment, further, see... Figure 1 , Figure 2 and Figure 6 The second thread cutter 3 is equipped with a thread-separating tip for inserting into the thread loops to separate the threads. The left side of the thread-separating tip is a hook-and-stop edge 306, which is shared with the thread-cutting hook 302. The right side of the thread-separating tip has a right-inclined thread-separating bevel 303. When the thread-cutting action begins, the second thread cutter 3 rotates, and the thread-separating tip inserts into the thread loops, separating them. The fabric edge thread is located on the left side of the thread-separating tip, i.e., in the thread-cutting hook 302, while the needle edge thread is located on the right side of the thread-separating tip and moves to the right along the thread-separating bevel 303 as the second thread cutter 3 rotates, thereby gradually separating the thread loops.

[0087] In this embodiment, see Figure 4 As a preferred design, the A-side end 105 of the arc-shaped capture plate 101 is chamfered or rounded to form an anti-collision notch 106. The anti-collision notch 106 and the first wire cutter 2 form a guide gap for the insertion of the second wire cutter 3, thereby facilitating the insertion of the second wire cutter 3 between the first wire cutter 2 and the arc-shaped capture plate 101.

[0088] As a preferred design, the component used for fixing the bobbin catching part 1 in the sewing machine is a catching part mounting base. For example, the catching part mounting base can be a rotary hook positioning hook. The mounting section 102 of the bobbin catching part 1 is a flat thin plate structure with a certain deformation capacity. The mounting section 102 can be provided with a tension adjustment hole (not shown in the figure). The tension adjustment hole is located on the side near the arc-shaped catching piece 101, and is screwed to the catching part mounting base by an adjusting screw passing through the tension adjustment hole. There is an adjustment gap between the tension adjustment hole and the catching part mounting base. At this time, by tightening or loosening the adjusting screw, the side of the mounting section 102 near the arc-shaped catching piece 101 can be deformed to a certain extent, changing the size of the adjustment gap between the tension adjustment hole and the catching part mounting base, thereby changing the contact pressure between the second catching part 103 and the first catching part 201, thereby changing the clamping force on the bobbin thread end. It is flexible and convenient to use and can meet different needs.

[0089] Example 2:

[0090] The difference between this embodiment and embodiment one is that the way the driving pressure block 402 presses the arc-shaped capture piece 101 to deform is different. In this embodiment, the bottom line capture piece 1 uses an arc-shaped capture piece 101 with a different structure, while the rest of the structure is the same.

[0091] See Figures 14 to 16 This is a schematic diagram of the bottom line capturing component 1 in this embodiment. In this embodiment, a protrusion 107 is provided on the outer arc surface of the arc-shaped capturing plate 101. When the driving pressure block 402 rotates during wire cutting, it moves onto the protrusion 107 on the outer arc surface of the arc-shaped capturing plate 101. Specifically, the surface of the protrusion 107 near the B side end 104 smoothly transitions with the outer arc surface of the arc-shaped capturing plate 101, and the surface of the protrusion 107 gradually increases in height from the B side end 104 to the A side end 105. The protrusion 107 is located on the right side of the arc-shaped capturing plate 101, which does not affect the smooth insertion of the second wire cutter 3 into the outer arc surface of the arc-shaped capturing plate 101.

[0092] When the wire cutting operation begins, the wire cutting drive mechanism drives the first blade holder 4 and the second blade holder 5 to rotate, which in turn drives the first wire cutting blade 2 and the second wire cutting blade 3 to rotate around the axis of the rotary hook assembly 6. During the rotation, the drive pressure block 402 contacts the outer arc surface of the arc-shaped capture piece 101. As it moves from the B side end 104 to the A side end 105, the drive pressure block 402 moves to the surface of the protrusion 107, thereby squeezing the arc-shaped capture piece 101 and bending it inward (towards the rotary hook assembly 6). The arc-shaped capture piece 101 separates from the first wire cutting blade 2, allowing the second wire cutting blade 3 to smoothly insert between the arc-shaped capture piece 101 and the first wire cutting blade 2. During the wire cutting, the drive pressure block 402 remains on the surface of the protrusion 107. After the wire cutting is completed, the first wire cutting blade 2, the second wire cutting blade 3, and the drive pressure block 402 all retract and reset, that is, the drive pressure block 402 leaves the protrusion 107, and the arc-shaped capture piece 101 resets elastically.

[0093] The other structures and principles in this embodiment are the same as those in Embodiment 1 above, and will not be described in detail here.

[0094] The bottom thread catcher 1 in this invention is located in the core area of ​​the sewing machine thread formation, and its distance from the rotary hook assembly 6 and the first thread cutter 2 is extremely small. Therefore, the outer edges of the entire part need to be rounded, polished, and hardened to ensure that its shape, toughness, strength, and edges are free from burrs. The arc-shaped catcher 101 and the mounting section 102 are integrated, and their processing methods can be ordinary sheet metal stamping, precision casting, lathe machining, or other modern parts processing techniques.

[0095] The double-blade thread-cutting mechanism of the present invention can be applied to conventional sewing machines, as well as large rotary hook flat sewing machines and heavy-duty sewing machines.

[0096] As can be seen from the above, the double-blade thread-cutting mechanism in this embodiment has the following beneficial effects: the structure is extremely simple, requiring only minor modifications to the existing double-blade thread-cutting mechanism's thread divider, optimizing its bent arc portion so that it can achieve the opening and closing of the bottom thread capture structure under the action of the driving pressure block 402; it can greatly improve the success rate of the double-blade thread-cutting mechanism sewing machine in successfully lifting the bottom thread and forming a lockstitch when starting to sew; and it solves the long-standing problem of starting to sew in double-blade computer thread-cutting sewing machines reported by customers.

[0097] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0098] 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 double-blade thread-cutting mechanism for a sewing machine, used for cutting thread at the rotary hook assembly (6) of the sewing machine, the double-blade thread-cutting mechanism comprising a first blade holder (4), a first thread-cutting blade (2) fixed on the first blade holder (4), a second blade holder (5), a second thread-cutting blade (3) fixed on the second blade holder (5), and a thread-cutting drive mechanism, wherein the first thread-cutting blade (2) and the second thread-cutting blade (3) are located on the outer periphery of the rotary hook assembly (6), and the thread-cutting drive mechanism drives the first blade holder (4) and the second blade holder (5) to rotate, such that the first thread-cutting blade (2) and the second thread-cutting blade (3) rotate around the axis of the rotary hook assembly (6) to approach or separate, wherein the second thread-cutting blade (3) is provided with a thread-cutting hook (302) for driving the bobbin thread toward the first thread-cutting blade (2), characterized in that: The double-blade wire cutting mechanism also includes a bottom thread catcher (1), which includes a fixed mounting section (102) and an arc-shaped catcher (101) connected to the mounting section (102). The arc-shaped catcher (101) is arranged along the outer periphery of the rotary hook assembly (6) and is located within the minimum rotation range of the first wire cutter (2). One end of the arc-shaped catcher (101) connected to the mounting section (102) is the B side end (104), and the other end facing the second wire cutter (3) is the A side end (105). The first wire cutter (2) has a first catcher (201) on its side facing the rotary hook assembly (6), and a second catcher (103) is provided on the outer arc surface of the arc-shaped catcher (101). When the first wire cutter (2) is not cutting the wire, the first catcher (201) and the second catcher (103) abut against each other. The first blade holder (4) A driving pressure block (402) is also fixed on the first wire cutter (2), and the driving pressure block (402) is located on the outer arc surface of the arc-shaped capture piece (101). When cutting the wire, the second wire cutter (3) and the first wire cutter (2) rotate to approach each other, and the driving pressure block (402) moves on the outer arc surface of the arc-shaped capture piece (101) and presses the arc-shaped capture piece (101) to bend or deflect towards the rotary hook assembly (6) to separate from the first wire cutter (2). The wire cutting hook (302) extends into the space between the first capture part (201) and the second capture part (103). The arc-shaped capture piece (101) can be reset when it is not squeezed by the driving pressure block (402). After the wire cutting is completed and the second wire cutter (3) leaves the space between the first wire cutter (2) and the arc-shaped capture piece (101), the first capture part (201) and the second capture part (103) re-contact to capture the bottom thread end.

2. The double-blade wire cutting mechanism according to claim 1, characterized in that: The distance between the B-side end (104) of the arc-shaped capture plate (101) and the rotary shuttle assembly (6) is smaller than the distance between the A-side end (105) and the rotary shuttle assembly (6).

3. The double-blade wire-cutting mechanism according to claim 1, characterized in that: The outer arc surface of the arc-shaped capture plate (101) is provided with a protrusion (107). When cutting the wire, the driving pressure block (402) will move on the protrusion (107) on the outer arc surface of the arc-shaped capture plate (101).

4. The double-blade wire-cutting mechanism according to claim 1, characterized in that: The driving block (402) has a smooth working surface for contacting the outer arc surface of the arc-shaped capture plate (101).

5. The double-blade wire-cutting mechanism according to claim 1, characterized in that: The mounting section (102) of the bottom line capture component (1) is fixedly connected to the arc-shaped capture piece (101), and the arc-shaped capture piece (101) itself can be bent and deformed.

6. The double-blade wire cutting mechanism according to claim 1, characterized in that: The mounting section (102) of the bottom line capture component (1) and the arc-shaped capture piece (101) are rotatably connected, and an elastic reset structure is provided between the arc-shaped capture piece (101) and the mounting section (102). When the arc-shaped capture piece (101) deflects toward the rotary shuttle assembly (6), the elastic reset structure is in an elastic energy storage state and provides an elastic force to reset the arc-shaped capture piece (101).

7. The double-blade wire-cutting mechanism according to claim 1, characterized in that: The anti-collision notch (106) is formed by chamfering the end of the A side (105) of the arc-shaped capture plate (101).

8. The double-blade wire cutting mechanism according to claim 1, characterized in that: The second wire cutter (3) is arc-shaped and coaxial with the rotary hook assembly (6).

9. The double-blade wire cutting mechanism according to claim 1, characterized in that: The first wire cutter (2) has a first cutting edge on the side facing the second wire cutter (3), and the second wire cutter (3) has a bulge (301) with a through hole in it. The bulge (301) forms a second cutting edge at the edge of the through hole. When cutting the wire, the first wire cutter (2) and the second wire cutter (3) approach each other and engage with the first cutting edge and the second cutting edge.

10. The double-blade wire cutting mechanism according to claim 1, characterized in that: It also includes an adjusting screw. The mounting section (102) of the bottom thread catcher (1) is a flat plate structure, and the mounting section (102) has a tension adjustment hole on the side near the arc-shaped catcher piece (101). The component used for fixing the bottom thread catcher (1) in the sewing machine is the catcher mounting base. The adjusting screw passes through the tension adjustment hole and is screwed into the catcher mounting base. There is an adjustment gap between the tension adjustment hole and the catcher mounting base. When the adjusting screw is tightened or loosened, it can cause the mounting section (102) to deform and change the contact pressure between the second catcher part (103) and the first catcher part (201).

11. The double-blade wire-cutting mechanism according to claim 1, characterized in that: The cutting hook (302) of the second wire cutter (3) is composed of a hooking bevel (305) and a hooking stop (306). The hooking bevel (305) extends obliquely to the right from the left side of the second wire cutter (3). The hooking stop (306) is located on the right side of the hooking bevel (305). The hooking stop (306) is obliquely arranged to the left and right, with the end closer to the bottom line capture member (1) located on the left and the end farther away from the bottom line capture member (1) located on the right. The end of the hooking stop (306) closer to the bottom line capture member (1) is located on the right side of the second capture part (103).

12. The double-blade wire-cutting mechanism according to claim 11, characterized in that: The angle of inclination of the hook-line guard relative to the front and back directions is 2~4°.

13. The double-blade wire-cutting mechanism according to claim 12, characterized in that: The angle of inclination of the hook-line guard relative to the front and rear directions is 3°.

14. A sewing machine, comprising a rotary hook mechanism, characterized in that: It also includes a double-blade wire-cutting mechanism as described in any one of claims 1 to 13, wherein the double-blade wire-cutting mechanism is disposed at the rotary hook assembly (6) in the rotary hook mechanism to cut the wire.

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