Sewing method for preventing upper thread of sewing machine from falling off and sewing machine
By controlling the coordination of the thread-cutting mechanism and the clamping components, the problem of thread slippage in lockstitch under various fabrics and complex sewing conditions is solved, achieving stable thread clamping and efficient sewing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- JACK SEWING MASCH CO LTD
- Filing Date
- 2026-03-31
- Publication Date
- 2026-05-12
AI Technical Summary
Existing lockstitch stitches are prone to thread breakage during sewing due to the variety of fabric materials and the complexity of sewing conditions, leading to thread breakage at the start of the stitch and affecting production efficiency and quality.
By controlling the movement of the thread-cutting mechanism in coordination with the movement of the needle, the clamping component stably clamps the thread after the first stitch, thus preventing the thread from coming loose.
It achieves stable clamping of the thread, prevents thread slippage, improves sewing efficiency and quality, has a simple structure, low cost, and is suitable for automated production lines.
Smart Images
Figure CN122013457A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of sewing equipment technology, and in particular to a sewing machine’s top thread anti-slipping start-up method, and a sewing machine. Background Technology
[0002] Lockstitch, the most commonly used stitch type in pattern sewing machines, is widely used in the sewing of clothing, bags, leather goods, and other products due to its advantages of simple structure, strong stitching, and low thread consumption. The stitch formation principle is as follows: after the needle drives the top thread to pierce the fabric, the rotary hook hooks the top thread to form a loop. Then, the take-up lever mechanism tightens the loop and pulls the bottom thread into the back of the fabric, causing the top and bottom threads to intertwine and lock together, thus completing the stitch formation.
[0003] However, lockstitch has inherent structural limitations: after the first needle pierces the fabric, an effective loop cannot be formed directly during the rotary hooking process. It relies on the first needle to embed the top thread into the fabric, providing a foundation for the loop formation of the second needle. With the diversification of fabric materials in industrial production (such as lightweight synthetic fibers, high-elasticity fabrics, and multi-layered composite fabrics) and the increasing complexity of sewing conditions (high-speed sewing, variable thickness sewing), the stability of existing lockstitch formation faces severe challenges. The top thread embedded in the fabric is easily pulled out under the traction of the second needle take-up lever due to the loose fiber structure and insufficient frictional resistance on the back of the fabric. This results in the second needle failing to form a complete loop, ultimately causing a thread slippage problem. Such thread slippage significantly increases the rework rate, severely impacting production efficiency, especially in mass production scenarios, and has become a key bottleneck restricting the improvement of sewing processing quality and capacity.
[0004] To address the issue of thread slippage at the start of lockstitch stitches, various solutions have been proposed in existing technologies, but each has its own drawbacks:
[0005] Parameter adjustment solutions: These solutions enhance the thread retention by enabling backstitching, setting a slow starting stitch, or extending the initial stitch length. While easy to operate, these solutions have the following drawbacks: backstitching increases stitch density, potentially leading to dense needle holes and fiber breakage in the fabric; a slow starting stitch directly reduces sewing efficiency; and the adaptability of parameter adjustments is extremely poor, failing to simultaneously meet the sewing requirements of fabrics of different thicknesses and materials.
[0006] Mechanism Improvement Solutions: Some technologies optimize the presser foot mechanism by using an independent stepper motor to drive its lifting and lowering, allowing the presser foot to pre-press the fabric during the start-up stage and reducing top thread displacement. While this solution can improve start-up stability to some extent, the structural modification is complex, requiring additional drive motors and electronic control systems, leading to increased equipment costs. Furthermore, it only addresses fabric loosening and cannot fundamentally improve the first stitch's resistance to pull-out, and it remains ineffective for high-smoothness fabrics.
[0007] Operational adjustment solutions: These involve manually optimizing the thread tension by adjusting the pressure of the high-pressure foot, cleaning impurities from the bobbin case, and adjusting the tension of the thread clamp. These methods rely on operator experience, have poor stability, and are prone to failure during high-speed sewing due to fabric displacement and thread tension fluctuations, making them unsuitable for automated production lines. Summary of the Invention
[0008] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a sewing machine with a method for preventing the top thread from detaching during the first stitch, and a sewing machine that controls the movement of the thread cutting mechanism in coordination with the movement of the needle, and works in conjunction with a clamping component to stably clamp the top thread after the first stitch, thereby preventing the problem of the top thread detaching during the first stitch.
[0009] To achieve the above objectives, the present invention provides a method for preventing the top thread from fraying during sewing in a sewing machine. The sewing machine has a thread-cutting mechanism, which includes a first thread-cutting blade for hooking the top thread and cutting it. The first thread-cutting blade has a thread groove and a first clamping part, and also includes a clamping assembly with a second clamping part. The method for preventing the top thread from fraying during sewing includes the following steps:
[0010] S1. Before starting the first stitch, the first thread cutter stops at working position A, at which point the thread groove is directly below the needle.
[0011] S2. Start sewing the first stitch. The needle moves downward, carrying the top thread through the thread guide and through the fabric. Then the rotary hook catches the top thread, and the needle rises above the first thread cutter. The top thread is located inside the thread guide.
[0012] S3. The first wire cutter moves toward the clamping assembly to the working position B, and through the wire slot, it drives the top wire to the second clamping part of the clamping assembly. The first clamping part approaches the second clamping part and clamps the top wire between the two. The first wire cutter stops at the working position B.
[0013] S4. The machine needle completes the subsequent stitching action of several stitches.
[0014] S5. The first wire cutter moves to the working position C, the first clamping part separates from the second clamping part, and the top thread is released.
[0015] Furthermore, the movement of the first wire cutter is driven by a wire cutting motor, the movement of the needle is driven by the main shaft, and the movements of both the wire cutting motor and the main shaft are controlled by an electronic control system;
[0016] In step S1, after receiving the sewing start signal, the electronic control system controls the thread cutting motor to run to the phase angle A corresponding to the working position A, so that the first thread cutting blade moves to the working position A and stops.
[0017] In step S2, the electronic control system, based on the phase angle A of the wire cutting motor, controls the rotation angle θ1 of the main shaft to make the needle rise to the first stop position above the first wire cutting knife and stop.
[0018] In step S3, the electronic control system automatically controls the wire cutting motor to run to the phase angle B corresponding to the working position B based on the rotation angle θ1 of the spindle, so that the first wire cutting blade moves to the working position B and stops.
[0019] In step S4, the electronic control system automatically controls the rotation angle θ2 of the main shaft based on the phase angle B of the thread cutting motor, so that the needle completes the subsequent stitching action.
[0020] In step S5, the electrical control system automatically controls the wire cutting motor to run to the phase angle C corresponding to the working position C based on the rotation angle θ2 of the spindle.
[0021] Furthermore, in step S3, the direction of movement of the first wire cutter from working position A to working position B is opposite to the direction of movement of the first wire cutter when it hooks the thread and cuts it.
[0022] Furthermore, in step S3, when the first thread cutter is in working position B, it completely avoids being directly below the needle.
[0023] Furthermore, in step S4, when the first thread cutter is in working position C, it completely avoids being directly below the needle, and when the first thread cutter moves from working position C toward the second thread cutter of the thread cutting mechanism, the hook groove will pass through the needle axis.
[0024] Furthermore, the first clamping part is disposed on the upper surface of the first wire cutter, and in step S3, when the first wire cutter is in working position B, it is inserted below the second clamping part of the clamping assembly.
[0025] Furthermore, the first clamping part includes a clamping protrusion on the upper surface of the first wire cutter.
[0026] Furthermore, in step S3, the thread-passing groove on the first thread cutter first passes through the second clamping part, and then the second clamping part approaches the first clamping part to clamp the thread.
[0027] Furthermore, the thread guide slot includes a needle slot and a guide slot. The first end of the guide slot is connected to the needle slot, and the second end extends along the direction from working position B to working position A. The width of the guide slot gradually decreases from the first end to the second end. In step S3, during the process of the thread guide slot driving the thread therein to the second clamping part, the thread moves from the first end of the guide slot to the second end and then falls towards the first clamping part.
[0028] Furthermore, the clamping assembly is provided with a V-shaped groove, which faces the first wire cutter located at working position A, and the width of the V-shaped groove gradually decreases along the direction from working position A to working position B. In step S3, the wire through the groove drives the surface wire into the V-shaped groove and reaches the bottom of the groove.
[0029] The present invention also provides a sewing machine including a thread cutting mechanism, the thread cutting mechanism having a first thread cutter for hooking the top thread and cutting the thread, and using the above-mentioned thread anti-slipping sewing method for starting the sewing.
[0030] As described above, the thread-prevention start-up method and sewing machine of the present invention have the following beneficial effects:
[0031] 1. By utilizing the action of the first thread cutter of the thread-cutting mechanism, combined with the timing of the needle's action, and through the cooperation of the clamping assembly, the thread guide groove on the first thread cutter, and the first clamping part, stable clamping of the top thread can be achieved during the start-up stitching process. This prevents the top thread from being pulled out of the fabric due to the thread-taking force, thus avoiding the problem of thread detachment. It can be improved based on the existing thread-cutting mechanism, requiring minimal changes to the structure and operation of the sewing machine, resulting in a simple structure and low cost.
[0032] 2. Through the sewing machine's electronic control system, the various steps of the anti-slipping sewing method can be automatically executed according to the set action sequence by automatically controlling the rotation angle of the main shaft and the thread cutting motor, thus achieving intelligent sewing. Attached Figure Description
[0033] Figure 1 This is a flowchart illustrating the method for preventing thread breakage and seam lifting of the present invention.
[0034] Figure 2 This is a schematic diagram of the clamping assembly, the first clamping part, and the wire passage in the present invention.
[0035] Figure 3 for Figure 2 Top view.
[0036] Figure 4 for Figure 3 The left-side view.
[0037] Figure 5 This is a schematic diagram of the structure of the first wire cutter, its wire-passing groove, and the first clamping part in this invention.
[0038] Figure 6 This is a schematic diagram of the pressure plate in this invention.
[0039] Figure 7 This is a schematic diagram of the conductor plate in this invention.
[0040] Figure 8 for Figure 7 The left-side view.
[0041] Explanation of icon numbers:
[0042] 1-First wire cutter, 11-First blade, 12-Hook groove, 2-Second wire cutter, 21-Second blade, 3-Clamping assembly, 301-Second clamping part, 302-V-shaped groove, 31-Pressure plate, 311-First guide bevel, 312-Pressure plate arc part, 313-Pressure plate mounting part, 314-First waist-shaped groove, 32-Wire guide plate, 321-Second guide bevel, 322-Wire guide plate arc part, 323-Bending connection part, 324-Wire guide plate mounting part, 325-Second waist-shaped groove, 33-Adjusting plate, 34-Adjusting bolt, 35-Fixed mounting block, 36-Fastening bolt, 4-Wire passage groove, 41-Needle threading groove, 42-Guide groove, 5-First clamping part, 6-Needle, 7-Rotary hook, 8-Moving knife drive component. Detailed Implementation
[0043] 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.
[0044] It should be understood that the structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes to aid those skilled in the art and to facilitate understanding. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and objectives of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention's implementation.
[0045] It should also be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on the other component or may be connected to an intermediary component. When a component is referred to as being "connected to" another component, it can be directly connected to the other component or indirectly connected to the other component through an intermediary component.
[0046] Furthermore, the use of terms such as "first" and "second" in this application is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. Additionally, the technical solutions of the various embodiments can be combined with each other, but only on the basis of being achievable by those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, such a combination of technical solutions should be considered non-existent and not within the scope of protection claimed in this application.
[0047] See Figures 1 to 8 This invention provides a method for preventing the top thread from detaching during sewing in a sewing machine. The sewing machine has a thread-cutting mechanism, which is a conventional mechanism for sewing machines. It has a first thread-cutting blade 1 for hooking the top thread and cutting it, and a second thread-cutting blade 2 that cooperates with the first thread-cutting blade 1. The first thread-cutting blade 1 is a movable blade that moves toward the second thread-cutting blade 2 when thread cutting is required. It hooks the top thread and bottom thread with its hook groove 12 and brings them close to the second thread-cutting blade 2. Then, the engagement of the first cutting edge 11 on the first thread-cutting blade 1 and the first cutting edge 21 on the second thread-cutting blade 2 cuts the top thread and bottom thread.
[0048] The improvement of this invention lies in that the first thread cutter 1 is provided with a thread groove 4 and a first clamping part 5, and also with a clamping assembly 3, which is provided with a second clamping part 301. As a preferred design, the movement of the first thread cutter is driven by a thread cutting motor (not shown in the figure), and the movement position of the first thread cutter 1 corresponds to a specific phase angle of the thread cutting motor; the movement of the sewing machine needle 6 is driven by the main shaft (not shown in the figure). By controlling the rotation angle of the main shaft, the running action and stopping position of the needle can be controlled. The movements of the thread cutting motor and the main shaft are both controlled by an electronic control system.
[0049] The method for preventing thread breakage and seam lifting of the present invention includes the following steps:
[0050] S1. Before starting the first stitch, the first thread cutter 1 stops at working position A, at which time the thread groove 4 is directly below the needle 6. Preferably, in this embodiment, the phase angle A of the thread cutting motor corresponding to the first thread cutter 1 at working position A can be preset in the electronic control system. After receiving the starting signal, the electronic control system controls the thread cutting motor to run to the phase angle A corresponding to working position A, so that the first thread cutter 1 moves to working position A and stops.
[0051] S2. The first stitch is started. The needle 6 moves downward, carrying the top thread through the thread guide 4 and through the fabric. Then, the rotary hook 7 hooks the top thread, and the needle 6 rises above the first thread cutter 1. The top thread (the end of the top thread on the back of the fabric) is located inside the thread guide 4. Preferably, in this embodiment, the needle 6 rises above the first thread cutter 1 and stops. This position is recorded as the first stop position, which corresponds to the rotation angle θ1 of the main shaft. The first stop position can be the upper limit position of the needle 6. The rotation angle θ1 is preset in the electronic control system. When the thread cutting motor reaches phase angle A, the signal is fed back to the electronic control system. Based on the phase angle A of the thread cutting motor, the electronic control system automatically issues a control command to control the rotation angle θ1 of the main shaft, so that the needle 6 rises to the first stitch position above the first thread cutter 1.
[0052] S3. The first wire cutter 1 moves towards the clamping assembly 3 to the working position B, passing through the wire slot 4 and bringing the surface wire therein to the second clamping part 301 of the clamping assembly 3. The first clamping part 5 approaches the second clamping part 301 and clamps the surface wire between the two. The first wire cutter 1 stops at the working position B. Preferably, in this embodiment, the phase angle B of the wire cutting motor corresponding to the first wire cutter 1 in the working position B is preset in the electronic control system. When the electronic control system controls the rotation angle of the spindle to θ1, a signal is fed back to the electronic control system. Thus, the electronic control system can issue a control command based on the rotation angle θ1 of the spindle to automatically control the wire cutting motor to run to the phase angle B, so that the first wire cutter 1 moves to the working position B and stops.
[0053] S4. The needle 6 completes the subsequent stitch-starting action. The number of stitches required after the first stitch can be determined according to actual needs, and the corresponding rotation angle of the main shaft is denoted as angle θ2. For example, if 3 more stitches need to be started after the first stitch, and the needle 6 finally stops at its highest position, the main shaft rotates 360° after the needle 6 completes one full reciprocating motion. In this case, angle θ2 is 360°*3. Angle θ2 is preset in the electronic control system. When the electronic control system controls the thread-cutting motor to run to phase angle B, the signal is fed back to the electronic control system. In this way, the electronic control system can issue control commands based on the phase angle B of the thread-cutting motor, thereby automatically controlling the rotation angle θ2 of the main shaft, so that the needle 6 automatically completes the subsequent stitch-starting action.
[0054] S5. The first thread cutter 1 moves to the working position C, the first clamping part 5 separates from the second clamping part 301, and the top thread is released. Preferably, in this embodiment, the phase angle C of the thread cutting motor corresponding to the first thread cutter 1 in the working position C can be preset in the electronic control system. When the electronic control system controls the rotation angle θ2 of the main shaft, the signal is fed back to the electronic control system. In this way, the electronic control system can automatically issue a control command based on the rotation angle θ2 of the main shaft, automatically control the thread cutting motor to run to the phase angle C, so that the first thread cutter 1 moves to the working position C and stops. The working position C of the first thread cutter 1 can be determined according to the actual position. Preferably, it moves a small distance from the working position B to the working position A, that is, it is located between the working position A and the working position B, so that the first clamping part 5 and the second clamping part 301 can smoothly release the top thread. When the first thread cutter 1 is in the working position C, it completely avoids being directly below the needle 6, so as not to affect the movement of the needle 6 during the subsequent normal sewing of the sewing machine. Furthermore, when the first thread cutter 1 moves from the working position C toward the second thread cutter 2 of the thread cutting mechanism, the hook groove 12 will pass through the axis of the needle 6, and can smoothly hook the top thread and bottom thread to perform the thread cutting action.
[0055] In this embodiment, see Figure 2 , Figure 3 and Figure 4 As a preferred design, the first clamping part 5 is disposed on the upper surface of the first thread cutter 1, with the lower side of the first thread cutter 1 facing the rotary hook 7 of the sewing machine. In step S3, when the first thread cutter 1 moves to position B, it is inserted below the second clamping part 301 of the clamping assembly 3, that is, inserted between the clamping assembly 3 and the rotary hook 7, so that the first clamping part 5 on the upper surface of the first thread cutter 1 is close to the second clamping part 301, thereby better clamping the thread. More preferably, the first clamping part 5 is a clamping protrusion protruding from the upper surface of the first thread cutter 1. The height of the protrusion can be determined according to the actual assembly gap. The clamping protrusion allows for a larger gap between the body of the first thread cutter 1 and the clamping assembly 3, avoiding interference during movement. The clamping protrusion can better contact and clamp the thread with the second clamping part 301 of the clamping assembly 3.
[0056] In this embodiment, see Figure 2 , Figure 3 and Figure 4As a preferred design, in step S3, the movement direction of the first wire cutter 1 from working position A to working position B is opposite to the movement direction when the first wire cutter 1 hooks the top thread to cut the thread. Specifically, the movement direction of the first wire cutter 1 when it hooks the top thread and moves towards the second wire cutter 2 to engage and cut the thread is denoted as the thread cutting movement direction. The direction in which the first wire cutter 1 moves towards the clamping assembly 3 is the anti-derailment movement direction, that is, the anti-derailment movement direction is opposite to the thread cutting movement direction. At this time, the first clamping part 5 is located on the side of the thread passage slot 4 where the thread cutting movement direction is located, as shown in the reference. Figure 2 , Figure 3 and Figure 4 For example, the first wire cutter 1 rotates. Viewed from a horizontal plane, the first wire cutter 1 rotates along the front-to-back direction. When rotating backward, it engages with the second wire cutter 2 to cut the wire; when rotating forward, it approaches the clamping assembly 3. In other words, the wire cutting direction is backward, and the anti-derailment direction is forward. At this time, the first clamping part 5 is located on the rear side of the wire passage slot 4. Using this method, in step S3, when the first wire cutter 1 moves to working position B, the wire passage slot 4 first passes through the second clamping part 301. The top wire then contacts the second clamping part 301 and tilts towards the side where the second clamping part 301 (clamping protrusion) is located, adhering to the clamping protrusion, thus effectively and stably clamping the top wire.
[0057] In this embodiment, see Figure 2 , Figure 3 and Figure 4 As a preferred design, when the first thread cutter 1 is in working positions B and C, the hook groove 12 is located in front of the axis of the needle 6, meaning the needle 6 is outside the range of the first thread cutter 1, completely avoiding interference with the downward movement of the needle 6, and eliminating the need for clearance slots on the first thread cutter 1. Especially in working position C, the hook groove 12 is located in front of the axis of the needle 6, awaiting normal sewing operations. That is, the hook groove 12 and the second thread cutter 2 of the thread cutting mechanism are located on opposite sides of the needle 6. Thus, when thread cutting is required, as the first thread cutter 1 moves backward toward the second thread cutter 2, the hook groove 12 will pass through the axis of the needle 6, smoothly hooking the bottom and top threads to the second thread cutter 2 for cutting.
[0058] In this embodiment, see Figure 2 , Figure 3 and Figure 5As a preferred design, the thread guide 4 includes a needle groove 41 and a guide groove 42. The needle groove 41 is a circular through hole with a radius larger than that of the sewing machine needle 6, through which the sewing machine needle 6 passes. The first end of the guide groove 42 is connected to the needle groove 41, and the second end extends along the direction from working position B to working position A, that is, the second end extends in the direction of thread cutting. The width of the guide groove 42 gradually decreases from the first end to the second end, forming an overall V-shape. The first clamping part 5 is located on the side where the second end of the guide groove 42 is located. Specifically, in this embodiment, the first end of the guide groove 42 is the front end, and the second end is the rear end. The front end of the guide groove 42 is connected to the needle groove 41, and the width (the dimension along the left and right direction) gradually decreases from front to back. The first clamping part 5 is located on the rear side of the rear end of the guide groove 42. In step S3, when the first wire cutter 1 moves toward the working position B, the first end of the guide groove 42 first reaches the clamping component 3 and then the second end reaches the clamping component 3. The wire in the wire slot 4 moves from the front end to the rear end in the guide groove 42 and is stably constrained at the rear end to prevent its position from fluctuating in the left and right directions. The wire at the second end leans toward the first clamping part 5 so that the wire is better aligned with the first clamping part 5, ensuring that the wire is stably clamped by the first clamping part 5 and the second clamping part 301.
[0059] In this embodiment, see Figure 2 , Figure 3 and Figure 5 More preferably, the first clamping part 5 is located outside the movement path of the first blade 11 and the hook groove 12 when the first wire cutter 1 moves along the wire cutting direction. Specifically, the first clamping part 5 is located to the right of the first blade 11 and the hook groove 12, and is a certain distance from the first blade 11 and the hook groove 12 in the left-right direction. At this time, the guide groove part 42 is inclined, gradually tilting to the right from front to back, so that the second end of the guide groove part 42 is also located to the right of the first blade 11 and the hook groove 12. With this design, the first clamping part 5 will not affect the normal operation of the first blade 11 and the hook groove 12 when the first wire cutter 1 is cutting wire, and the modification to the existing wire cutting mechanism is small.
[0060] In this embodiment, see Figure 2 , Figure 3 and Figure 4The clamping assembly 3 is provided with a V-shaped groove 302. The second clamping part 301 is located at the bottom of the V-shaped groove 302. In step S3, when the first wire cutter 1 moves toward the working position B, the movement path of the wire passage 4 is within the range of the V-shaped groove 302, so that the surface wire in the wire passage 4 enters the V-shaped groove 302 and can move along the two sides of the V-shaped groove 302 to the bottom. Specifically, in this embodiment, the V-shaped groove 302 is located at the rear side of the clamping assembly 3, and its width gradually narrows from back to front. The bottom position of the V-shaped groove 302 is aligned with the first clamping part 5 (clamping protrusion). When the first wire cutter 1 moves toward the clamping assembly 3 to the working position B, the surface wire in the wire groove 4 will enter the range of the V-shaped groove 302. Guided by the inclined sides on both sides of the V-shaped groove 302, it will smoothly enter the bottom of the V-shaped groove 302, thereby accurately aligning with the first clamping part 5 (clamping protrusion) and then adhering to the first clamping part 5 (clamping protrusion) to achieve stable clamping.
[0061] In this embodiment, see Figure 2 , Figure 3 and Figure 4 As a preferred design, the clamping assembly 3 includes a pressure plate 31 and a guide plate 32, as well as a fixing block 35 for fixing the pressure plate 31 and the guide plate 32. The fixing block 35 is fixed in the sewing machine, and the pressure plate 31 and the guide plate 32 can be fixed to the fixing block 35 by fastening bolts 36. The pressure plate 31 is provided with a first guide bevel 311, and the guide plate 32 is provided with a second guide bevel 321. The guide plate 32 presses against the upper side of the pressure plate 31, and the first guide bevel 311 and the second guide bevel 321 intersect to form a V-shaped groove 302. That is, the first guide bevel 311 and the second guide bevel 321 constitute the bevels on both sides of the V-shaped groove 302. The second clamping part 301 is located on the lower side of the pressure plate 31, and the first thread cutter 1 is inserted into the lower side of the pressure plate 31 when it moves toward the clamping assembly 3. The clamping assembly 3 and the V-shaped groove 302 are composed of a pressure plate 31 and a wire guide plate 32. By adjusting the positional relationship between the pressure plate 31 and the wire guide plate 32, the width and bottom position of the V-shaped groove 302 can be adjusted, thereby adjusting its relative position with the first clamping part 5 on the first wire cutter 1, better matching the clamping surface wire, and making it more flexible and convenient to use. In other embodiments, the pressure plate 31 and the wire guide plate 32 can also be an integral structure, that is, a single plate. In this case, the shape of the V-shaped groove 302 is fixed, and its size can be set appropriately according to actual needs. The clamping assembly 3 can also adopt other suitable shapes and structures.
[0062] In this embodiment, see Figure 2 , Figure 4 and Figure 6As a preferred design, the pressure plate 31 includes a pressure plate arc-shaped portion 312 and a pressure plate mounting portion 313. The pressure plate arc-shaped portion 312 is arranged along the outer periphery of the rotary hook 7 of the sewing machine, and the inner arc surface of the pressure plate arc-shaped portion 312 faces the rotary hook 7. There is an appropriate gap between them, allowing the first thread cutter 1 to be inserted between the pressure plate arc-shaped portion 312 and the rotary hook 7. The rear side of the pressure plate arc-shaped portion 312 faces the first thread cutter 1 and forms a first guide bevel 311. The second clamping portion 301 is located on the inner arc surface of the pressure plate arc-shaped portion 312 and is close to the first guide bevel 311. In step S3 above, when the first wire cutter 1 moves toward the clamping assembly 3 to the working position B, the first wire cutter 1 is inserted between the inner arc surface of the pressure plate arc portion 312 and the rotary hook 7, and the first clamping portion 5 (clamping protrusion) on the upper surface of the first wire cutter 1 is close to the second clamping portion 301 on the inner arc surface of the pressure plate arc portion 312, and the gap between the two is less than the diameter of the wire, thus clamping the wire. The pressure plate 31 is fixed to the fixed mounting block 35 via the pressure plate mounting part 313. Preferably, the pressure plate mounting part 313 is provided with a first waist-shaped groove 314. The length of the first waist-shaped groove 314 extends along the direction of action, that is, perpendicular to the direction of movement of the first wire cutter 1. The fastening bolt 36 passes through the first waist-shaped groove 314 and is connected to the fixed mounting block 35 to fix the pressure plate mounting part 313. The position of the pressure plate 31 in the left and right directions can be adjusted through the first waist-shaped groove 314. The corresponding contact position of the first guide inclined edge 311 and the first clamping part 5 (clamping protrusion) can be adjusted, that is, the position of the second clamping part 301 can be finely adjusted, which facilitates installation and is flexible and convenient to use.
[0063] In this embodiment, see Figure 2 , Figure 4 and Figure 7 As a preferred design, the conductor plate 32 includes an arc-shaped portion 322 and a mounting portion 324. The arc-shaped portion 322 is arranged along the outer arc surface of the pressure plate arc-shaped portion 312 and presses against the outer arc surface. The rear side of the arc-shaped portion 322 faces the first wire cutter 1 and forms a second guide bevel 321. The conductor plate 32 is fixed to the mounting block 35 via the mounting portion 324. Preferably, the mounting portion 324 has a second waist-shaped groove 325. Fastening bolts 36 pass through the second waist-shaped groove 325 and connect to the mounting block 35 to fix the pressure plate mounting portion 313. The position of the conductor plate 32 can be adjusted via the second waist-shaped groove 325, facilitating its installation and cooperation with the pressure plate 31 and the first clamping portion 5, making it flexible and convenient to use.
[0064] In this embodiment, see Figure 2 , Figure 4 , Figure 7 and Figure 8As a preferred design, the clamping assembly 3 also includes an adjusting part for adjusting the gap between the second clamping part 301 and the first wire cutter 1, so as to adjust according to the size of the thread and the specific working conditions, ensuring that the thread can be clamped while avoiding cutting the thread. Specifically, the adjusting part includes an adjusting plate 33 fixed to the pressure plate mounting part 313 and an adjusting bolt 34 screwed to the adjusting plate 33. The adjusting bolt 34 is located above the guide plate 32 and is pressed on the guide plate 32. By pressing down, the upper and lower positions of the arc-shaped part 322 of the guide plate and the arc-shaped part 312 of the pressure plate are changed, and the gap between the arc-shaped part 312 of the pressure plate and the rotary hook 7 is adjusted, thereby realizing the adjustment of the gap between the second clamping part 301 and the first wire cutter 1. Preferably, the conductor plate 32 further includes a bent connecting portion 323 connecting the arc-shaped portion 322 of the conductor plate and the conductor plate mounting portion 324. The bent connecting portion 323 is V-shaped. The adjusting bolt 34 presses against the bent connecting portion 323, which can change its deformation state, thereby adjusting the position of the arc-shaped portion 322 of the conductor plate. In other embodiments, the adjusting portion can also adopt other suitable structures, as long as they can achieve the gap adjustment between the second clamping portion 301 and the first wire cutter 1.
[0065] This invention also provides a sewing machine, including a thread-cutting mechanism. The thread-cutting mechanism includes a first thread-cutting blade 1 for hooking and cutting the top thread, and a second thread-cutting blade 2 that cooperates with the first thread-cutting blade 1. The first thread-cutting blade 1 is a movable blade, preferably a thin plate with an arc shape, arranged around the periphery of the rotary hook 7 and coaxial with rotation. The first thread-cutting blade 1 rotates around the periphery of the rotary hook 7. The first thread-cutting blade 1 is mounted on a movable blade drive member 8, which is driven by a thread-cutting drive motor. The sewing machine uses the above-mentioned top thread anti-slipping sewing method to start the sewing operation. By setting a clamping component 3 on the upper side of the rotary hook 7, and providing a thread groove 4 and a first clamping part 5 on the first thread-cutting blade 1, the sewing machine executes the above steps S1 to S5 when starting the sewing. Preferably, a corresponding control program is set in the electrical control system of the sewing machine. After receiving the sewing start signal, the control program automatically executes steps S1 to S5.
[0066] As can be seen from the above, the thread anti-fraying start-up method and sewing machine of the present invention have the following beneficial effects:
[0067] 1. By utilizing the action of the first thread cutter 1 of the thread cutting mechanism, and in conjunction with the action sequence of the needle 6, the clamping assembly 3 and the thread groove 4 and the first clamping part 5 on the first thread cutter 1 can achieve stable clamping of the top thread during sewing, so that the top thread will not be pulled out of the back of the fabric due to the thread take-up force, thus avoiding the problem of thread detachment. It can be improved based on the existing thread cutting mechanism, with minimal changes to the structure and operation of the sewing machine, simple structure, and low cost.
[0068] 2. Through the sewing machine's electronic control system, the various steps of the anti-slipping sewing method can be automatically executed according to the set action sequence by automatically controlling the rotation angle of the main shaft and the thread cutting motor, thus achieving intelligent sewing.
[0069] 3. The clamping component 3 can be flexibly adjusted according to actual needs. The gap between the clamping component 3 and the first wire cutter 1 can be adjusted, thereby adjusting the gap between the first clamping part 5 and the second clamping part 301 in the clamping working state to meet the needs of different sizes of face wires. The relative positional relationship between the clamping component 3 and the first clamping part 5 can also be adjusted to better stabilize the clamping of the face wire.
[0070] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.
[0071] 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 method for preventing the sewing thread from slipping during sewing in a sewing machine, the sewing machine having a thread-cutting mechanism, the thread-cutting mechanism having a first thread-cutting blade (1) for hooking the thread and cutting it, characterized in that: The first thread cutter (1) is provided with a thread passage slot (4) and a first clamping part (5), and is also provided with a clamping assembly (3), wherein the clamping assembly (3) is provided with a second clamping part (301); the method for preventing the top thread from detaching and starting to sew includes the following steps: S1. Before starting the first stitch, the first thread cutter (1) stops at working position A, at which time the thread groove (4) is located directly below the needle (6); S2. Start sewing the first stitch. The needle (6) moves downward, carrying the top thread through the thread guide (4) and through the fabric. Then the rotary hook (7) hooks the top thread, and the needle (6) rises above the first thread cutter (1), with the top thread inside the thread guide (4). S3. The first wire cutter (1) moves toward the clamping assembly (3) to the working position B, passes through the wire slot (4) and drives the face wire therein to the second clamping part (301) of the clamping assembly (3). The first clamping part (5) approaches the second clamping part (301) and clamps the face wire between the two. The first wire cutter (1) stops at the working position B. S4, the needle (6) completes the subsequent stitching action; S5. The first wire cutter (1) moves to the working position C, the first clamping part (5) separates from the second clamping part (301), and the top thread is released.
2. The method for preventing thread breakage and seam lifting according to claim 1, characterized in that: The movement of the first wire cutter (1) is driven by the wire cutting motor, and the movement of the needle (6) is driven by the main shaft. The movements of the wire cutting motor and the main shaft are both controlled by the electronic control system. In step S1, after receiving the sewing start signal, the electrical control system controls the wire cutting motor to run to the phase angle A corresponding to the working position A, so that the first wire cutting blade (1) moves to the working position A and stops. In step S2, the electronic control system controls the rotation angle θ1 of the main shaft based on the phase angle A of the wire cutting motor, so that the needle (6) rises to the first stop position above the first wire cutting knife (1) and stops. In step S3, the electrical control system automatically controls the wire cutting motor to run to the phase angle B corresponding to the working position B based on the rotation angle θ1 of the spindle, so that the first wire cutting blade (1) moves to the working position B and stops. In step S4, the electrical control system automatically controls the rotation angle θ2 of the main shaft based on the phase angle B of the thread cutting motor, so that the needle (6) completes the subsequent stitching action. In step S5, the electrical control system automatically controls the wire cutting motor to run to the phase angle C corresponding to the working position C based on the rotation angle θ2 of the spindle.
3. The method for preventing thread breakage and seam lifting according to claim 1, characterized in that: In step S3, the direction of movement of the first wire cutter (1) from working position A to working position B is opposite to the direction of movement of the first wire cutter (1) when it hooks the face wire to cut the wire.
4. The method for preventing thread breakage and seam lifting according to claim 1, characterized in that: In step S3, when the first thread cutter (1) is in working position B, it completely avoids the area directly below the needle (6).
5. The method for preventing thread breakage and seam lifting according to claim 1, characterized in that: In step S4, when the first thread cutter (1) is in working position C, it completely avoids the direct underside of the needle (6), and when the first thread cutter (1) moves from working position C toward the second thread cutter (2) of the thread cutting mechanism, the hook groove (12) will pass through the axis of the needle (6).
6. The method for preventing thread breakage and seam lifting according to claim 1, characterized in that: The first clamping part (5) is disposed on the upper surface of the first wire cutter (1). In step S3, when the first wire cutter (1) is in working position B, it is inserted below the second clamping part (301) of the clamping assembly (3).
7. The method for preventing thread breakage and seam lifting according to claim 1 or 6, characterized in that: The first clamping part (5) includes a clamping protrusion on the upper surface of the first wire cutter (1).
8. The method for preventing thread breakage and seam lifting according to claim 1, characterized in that: In step S3, the thread-passing groove (4) on the first thread cutter (1) passes through the second clamping part (301) first, and then the second clamping part (301) approaches the first clamping part (5) to clamp the thread.
9. The method for preventing thread slippage and seam opening according to claim 1 or 8, characterized in that: The thread-passing slot (4) includes a needle-passing slot (41) and a guide slot (42). The first end of the guide slot (42) is connected to the needle-passing slot (41), and the second end extends along the direction from working position B to working position A. The width of the guide slot (42) gradually decreases from the first end to the second end. In step S3, during the process of the thread-passing slot (4) driving the thread to the second clamping part (301), the thread moves from the first end of the guide slot (42) to the second end and falls towards the first clamping part (5).
10. The method for preventing thread breakage and seam lifting according to claim 1 or 8, characterized in that: The clamping assembly (3) is provided with a V-shaped groove (302), which faces the first wire cutter (1) located at working position A, and the width of the V-shaped groove (302) gradually decreases along the direction from working position A to working position B. In step S3, the wire through groove (4) drives the surface wire therein into the V-shaped groove (302) and reaches the bottom of the groove.
11. A sewing machine comprising a thread-cutting mechanism having a first thread-cutting blade (1) for hooking the thread and cutting it, characterized in that: The seam-starting operation is carried out using the anti-loosening seam-starting method as described in any one of claims 1 to 10.