Thread loosening mechanism for a lockstitch machine

Abstract

This utility model relates to the field of flat sewing machine technology, specifically a thread loosening mechanism for a flat sewing machine. It includes an installation tube with a thread clamp at one end and a thread loosening rod at the other end. A fixed sleeve is detachably fitted onto the installation tube, and a movable ring is movably fitted onto the fixed sleeve. A guide rod is fixed to the outer peripheral wall of the movable ring. A mounting seat is movably fitted onto the guide rod, and a wiping plate for cleaning the thread clamping surface of the thread clamp is fixed on the mounting seat. Through the cooperation of the fixed sleeve, movable ring, guide rod, mounting seat, wiping plate, and return spring, this utility model ensures that, under normal conditions, the wiping plate is in a non-interference position beside the thread clamp, preventing accidental contact between the wiping plate and the thread clamping disc or top thread of the thread clamp. When the thread clamping surface of the thread clamp is covered with fabric scraps or lint and needs cleaning, the spatial orientation and position of the wiping plate can be flexibly changed to wipe and clean the thread clamping surface, ensuring the stability of the top thread conveying speed.

Description

Technical Field

[0001] This utility model relates to the field of flat sewing machine technology, specifically to a flat sewing machine thread loosening mechanism. Background Technology

[0002] The loosening mechanism is mainly used to temporarily adjust the tension of the top thread when the flat sewing machine is performing processes such as thread cutting and presser foot lifting. This prevents the top thread from becoming too tight, causing the fabric to wrinkle or break, while also ensuring smooth top thread feeding when starting the stitch.

[0003] The thread loosening mechanism of a flatbed sewing machine typically includes a thread loosening rod and a thread clamp. When the thread cutting handle, presser foot lever, or button on an electronic model is operated, the power source of the thread loosening mechanism is triggered (lever transmission in mechanical models, electromagnet in electronic models). The power source pushes the thread loosening rod, which squeezes the thread clamping plates of the thread clamp, increasing the gap between the clamping plates and reducing the clamping force (tension) on the top thread, thus loosening the thread.

[0004] However, in actual sewing processes, since the fabrics processed by flatbed sewing machines are mostly cotton, synthetic fibers, and knitted materials, fabric fibers generate lint during sewing, and the high-speed movement of the top thread also causes thread fibers to fall off. These lint and thread fibers easily adhere to the thread clamping surface of the clamping plate. As the sewing operation continues, the accumulation of lint and thread fibers on the clamping surface gradually increases, which increases the friction between the top thread and the clamping surface, leading to unstable top thread feed speed. To address this, we propose a thread loosening mechanism for flatbed sewing machines to effectively solve the above-mentioned drawbacks. Utility Model Content

[0005] The purpose of this invention is to provide a thread loosening mechanism for a flat sewing machine, which solves the problem mentioned in the background art that foreign objects on the thread clamping surface can cause unstable thread conveying speed.

[0006] This utility model is achieved through the following technical solution: a thread loosening mechanism for a flat sewing machine, including an installation tube, one end of which is provided with a thread clamp and the other end with a thread loosening rod. The thread loosening rod is used to drive the thread clamp to loosen the top thread. A fixed sleeve is detachably fitted on the installation tube, and a movable ring is movably fitted on the fixed sleeve. The movable ring can move along the axial direction of the fixed sleeve and can rotate around the axis of the fixed sleeve.

[0007] A guide rod is fixed on the outer peripheral wall of the movable ring, and the axis of the guide rod is perpendicular to the axis of the movable ring; a mounting seat is movably sleeved on the guide rod, and a wiping plate for cleaning the clamping surface of the wire clamp is fixed on the mounting seat;

[0008] A return spring is fitted on the guide rod, and the return spring is located between the mounting base and the movable ring. Under normal conditions, the return spring is in a slightly compressed state and always applies a spring force to the mounting base away from the movable ring.

[0009] Optionally, the wire clamp includes a fixed wire clamping disc, a movable wire clamping disc, a tension spring, and a spring top seat;

[0010] The fixed clamping disc is fixed to the mounting tube, the movable clamping disc is movably sleeved on the mounting tube, the spring top seat is installed at the end of the mounting tube, and the tension spring is sleeved on the mounting tube and located between the spring top seat and the movable clamping disc.

[0011] Under normal conditions, the tension spring is in a slightly compressed state, always applying a spring force close to that of the fixed clamping plate to the movable clamping plate;

[0012] The slack rod is coaxially arranged with the mounting tube and movably passes through the mounting tube. A connector is fixed between the slack rod and the movable clamping disc. A strip hole is opened on the mounting tube for the connector to pass through and slide along the axial direction.

[0013] Optionally, the movable ring has a plurality of ball grooves circumferentially formed at one end near the wire clamp, and each ball groove is rotatably installed with a ball.

[0014] Optionally, a retaining ring is fixed to the end of the fixed sleeve away from the wire clamp, and the outer diameter of the retaining ring is larger than the outer diameter of the movable ring;

[0015] A ring magnet is embedded at one end of the retaining ring near the movable ring, and a ring magnet that cooperates with the ring magnet is fixed at one end of the movable ring near the retaining ring.

[0016] Optionally, the inner peripheral wall of the movable ring is provided with a plurality of guide grooves along the circumferential direction, and each guide groove extends along the axial direction of the movable ring; the outer peripheral wall of the fixed sleeve is fixed with guide ribs corresponding to each guide groove.

[0017] Optionally, the guide rod is an external hexagonal rod, and a limit nut is threadedly connected to the end of the guide rod.

[0018] Compared with the prior art, this utility model provides a thread loosening mechanism for a flat sewing machine, which has the following beneficial effects:

[0019] This invention utilizes the coordinated components of a fixed sleeve, a movable ring, a guide rod, a mounting base, a wiping plate, and a return spring. Under normal conditions, the wiping plate is positioned in a non-interference location beside the wire clamp, preventing accidental contact between the wiping plate and the clamping disc or thread of the wire clamp, while also ensuring the normal clamping / loosening action of the wire clamp. When the clamping surface of the wire clamp is covered with cloth scraps or lint and needs cleaning, the spatial orientation and position of the wiping plate can be flexibly adjusted to clean the clamping surface, ensuring the stability of the thread conveying speed. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0021] Figure 2 for Figure 1 A diagram from another perspective;

[0022] Figure 3 This is a schematic diagram of the fixing sleeve of this utility model;

[0023] Figure 4 This is a schematic diagram of the movable ring of this utility model;

[0024] Figure 5 for Figure 4 A diagram from another perspective.

[0025] In the diagram: 1. Mounting tube; 2. Wire clamp; 201. Fixed wire clamping disc; 202. Movable wire clamping disc; 203. Tension spring; 204. Spring top seat; 3. Wire loosening rod; 4. Fixed sleeve; 5. Movable ring; 6. Guide rod; 7. Mounting seat; 8. Wiping plate; 9. Return spring; 10. Ball bearing; 11. Retaining ring; 12. Ring magnet; 13. Ring magnet; 14. Guide rib; 15. Limit nut. Detailed Implementation

[0026] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0027] Please see Figures 1 to 5 A thread loosening mechanism for a flat sewing machine includes an installation tube 1, which is a cylindrical hollow structure and fixed to the body of the flat sewing machine. One end of the installation tube 1 (the end closer to the fabric sewing area) is provided with a thread clamp 2, and the other end (the end away from the sewing area) is provided with a thread loosening rod 3. The thread loosening rod 3 is used to drive the thread clamp 2 to loosen the top thread, thereby realizing dynamic switching of tension during the sewing process.

[0028] The following is a description of wire clamp 2:

[0029] The wire clamp 2 includes a fixed wire clamping disc 201, a movable wire clamping disc 202, a tension spring 203, and a spring top seat 204. The fixed wire clamping disc 201 is fixed to the mounting tube 1, with its disc surface perpendicular to the axis of the mounting tube 1. The movable wire clamping disc 202 is movably sleeved on the mounting tube 1, with its disc surface parallel to and opposite to the disc surface of the fixed wire clamping disc 201, forming a clamping gap between them for the thread to pass through. The spring top seat 204 is installed at the end of the (threaded connection) mounting tube 1 to define the installation position of the tension spring 203. The tension spring 203 is sleeved on the mounting tube 1 and located between the spring top seat 204 and the movable wire clamping disc 202.

[0030] Under normal conditions, the tension spring 203 is in a slightly compressed state, constantly applying a spring force close to the fixed tension plate 201 to the movable thread clamping plate 202, thus reducing the clamping gap between the two and clamping the thread passing through. At this time, the tension on the thread is determined by the compression of the tension spring 203, ensuring that the stitch is tight and uniform. When the sewing machine performs actions that require loosening the thread, such as cutting the thread or lifting the presser foot, the thread loosening rod 3 drives the movable thread clamping plate 202 to move away from the fixed tension plate 201 by axial movement, overcoming the spring force of the tension spring 203. This increases the clamping gap, releases the thread tension, and completes the thread loosening action.

[0031] To achieve linkage between the slack rod 3 and the movable clamping disc 202, the slack rod 3 is coaxially arranged with the mounting tube 1 and movably inserted inside the mounting tube 1. A connector (not shown in the figure) is fixed between the slack rod 3 and the movable clamping disc 202. A strip-shaped hole (not shown in the figure) is provided on the mounting tube 1 for the connector to pass through and slide axially. When the slack rod 3 extends or retracts axially, the connector drives the movable clamping disc 202 to move axially synchronously through the guiding action of the strip-shaped hole, thereby precisely controlling the size of the clamping gap.

[0032] In this embodiment, a fixing sleeve 4 is detachably (with countersunk screws) fitted onto the mounting tube 1 for easy maintenance or component replacement. A movable ring 5 is movably fitted onto the fixing sleeve 4. The movable ring 5 can move along the axial direction of the fixing sleeve 4 and rotate around the axis of the fixing sleeve 4, achieving flexible adjustment of its spatial position through dual degrees of freedom of motion. A guide rod 6 is fixed on the outer peripheral wall of the movable ring 5, and the axis of the guide rod 6 is perpendicular to the axis of the movable ring 5. A mounting seat 7 is movably fitted onto the guide rod 6. The mounting seat 7 can move along the axial direction of the guide rod 6. A wiping pad 8 for cleaning the clamping surface of the wire clamp 2 is fixed on the mounting seat 7. The wiping pad 8 is made of a flexible and wear-resistant material (such as nylon felt).

[0033] It should be noted that the guide rod 6 is an external hexagonal rod, which allows the mounting base 7 to move only along the axial direction of the guide rod 6. A limit nut 15 is threadedly connected to the end of the guide rod 6. When it is necessary to clean, maintain, or replace the wiping plate 8, simply unscrew the limit nut 15, and the mounting base 7 along with the wiping plate 8 can be removed along the axial direction of the guide rod 6. The operation is simple and convenient for maintenance and replacement.

[0034] To achieve automatic reset of the mounting base 7, a reset spring 9 is sleeved on the guide rod 6. The reset spring 9 is located between the mounting base 7 and the movable ring 5. Under normal conditions, the reset spring 9 is in a slightly compressed state, always applying a spring force away from the movable ring 5 to the mounting base 7, so that the wiping pad 8 remains in the initial standby position.

[0035] With the above design, during normal sewing, the movable ring 5 is located in an area far away from the fixed thread clamping plate 201; at the same time, under the pushing force of the return spring 9, the mounting base 7 drives the wiping plate 8 to a safe position far away from the thread clamp 2, so that it does not come into contact with the fixed thread clamping plate 201 or the movable thread clamping plate 202, nor does it interfere with the normal conveying of the thread, ensuring that the tension control of the thread clamp 2 is not affected.

[0036] When the clamping surface of the wire clamp 2 is covered with cloth scraps and lint and needs to be cleaned, first push the movable ring 5 along the axial direction of the fixed sleeve 4, so that it drives the guide rod 6, the mounting base 7 and the wiping plate 8 to move as a whole towards the fixed clamping plate 201, until the wiping plate 8 reaches above the wire clamp 2.

[0037] Then, manually press the mounting base 7 to make it slide along the guide rod 6 towards the movable ring 5, overcoming the elastic force of the return spring 9, and drive the wiping plate 8 to extend into the gap between the fixed clamping plate 201 and the movable clamping plate 202.

[0038] Then, while maintaining the pressing state, manually rotate the movable ring 5 to make it rotate around the axis of the fixed sleeve 4. The wiping plate 8 rotates synchronously with the movable ring 5 to wipe the wire clamping surfaces where the fixed wire clamping plate 201 and the movable wire clamping plate 202 are in contact, and thoroughly remove the attached impurities.

[0039] After cleaning, loosen the mounting base 7, and the return spring 9 will push the mounting base 7 and the wiping plate 8 back to their original positions, disengaging them from the thread clamping gap. Then, push the movable ring 5 back to its initial position to resume normal sewing.

[0040] To further optimize the smoothness of the movement of the movable ring 5, several ball grooves are formed circumferentially at the end of the movable ring 5 near the wire clamp 2, and each ball groove is fitted with a rolling ball 10. When the movable ring 5 moves axially along the fixed sleeve 4 and approaches the fixed wire clamping plate 201, the ball 10 can form rolling contact with the side of the fixed wire clamping plate 201, transforming the traditional surface contact friction into rolling friction, and significantly reducing the frictional resistance between the two.

[0041] It is worth mentioning that a retaining ring 11 is fixed to the end of the fixed sleeve 4 away from the wire clamp 2. The outer diameter of the retaining ring 11 is larger than the outer diameter of the movable ring 5. This retaining ring 11 can block the movable ring 5 when it moves axially away from the wire clamp 2 along the fixed sleeve 4, preventing it from falling off due to accidental vibration or misoperation. A ring magnet 12 is embedded at the end of the retaining ring 11 near the movable ring 5. A ring magnet 13 that cooperates with the ring magnet 12 is fixed at the end of the movable ring 5 near the retaining ring 11. The opposing surfaces of the ring magnet 13 and the ring magnet 12 are arranged with opposite poles. Under normal conditions, the two attract each other through magnetic attraction, so that the movable ring 5 is stably stopped at the retaining ring 11, ensuring that it is away from the fixed wire clamping plate 201 and avoiding interference with the normal operation of the wire clamp 2.

[0042] To limit unnecessary rotation of the movable ring 5, several guide grooves are formed circumferentially on the inner peripheral wall of the movable ring 5, each extending axially along the movable ring 5; guide ribs 14 corresponding to each guide groove are fixed on the outer peripheral wall of the fixed sleeve 4. Under normal conditions, this structure can work in conjunction with magnetic attraction to further constrain the rotational freedom of the movable ring 5 around the axis of the fixed sleeve 4, preventing accidental rotation due to equipment vibration that could cause the wiping pad 8 to shift. When it is necessary to clean the wire clamp 2, the movable ring 5 can be moved away from the guide ribs 14, allowing the movable ring 5 to rotate along the axis of the fixed sleeve 4.

[0043] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0044] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A thread loosening mechanism for a flat sewing machine, comprising an installation tube (1), one end of which is provided with a thread clamp (2), and the other end with a thread loosening rod (3), wherein the thread loosening rod (3) is used to drive the thread clamp (2) to loosen the top thread, characterized in that: A fixed sleeve (4) is detachably fitted on the mounting tube (1), and a movable ring (5) is movably fitted on the fixed sleeve (4). The movable ring (5) can move along the axial direction of the fixed sleeve (4) and can rotate around the axis of the fixed sleeve (4). A guide rod (6) is fixed on the outer peripheral wall of the movable ring (5), and the axis of the guide rod (6) is perpendicular to the axis of the movable ring (5); a mounting seat (7) is movably sleeved on the guide rod (6), and a wiping plate (8) for cleaning the clamping surface of the wire clamp (2) is fixed on the mounting seat (7). A return spring (9) is sleeved on the guide rod (6). The return spring (9) is located between the mounting base (7) and the movable ring (5). Under normal conditions, the return spring (9) is in a slightly compressed state and always applies a spring force to the mounting base (7) away from the movable ring (5).

2. The thread loosening mechanism of a flat sewing machine according to claim 1, characterized in that: The wire clamp (2) includes a fixed wire clamping plate (201), a movable wire clamping plate (202), a tension spring (203), and a spring top seat (204). The fixed clamping disc (201) is fixed on the mounting tube (1), the movable clamping disc (202) is movably sleeved on the mounting tube (1), the spring top seat (204) is installed at the end of the mounting tube (1), and the tension spring (203) is sleeved on the mounting tube (1) and located between the spring top seat (204) and the movable clamping disc (202); Under normal conditions, the tension spring (203) is in a slightly compressed state, and always applies a spring force close to the fixed clamping plate (201) to the movable clamping plate (202); The slack rod (3) is coaxially arranged with the mounting tube (1) and is movably inserted inside the mounting tube (1). A connector is fixed between the slack rod (3) and the movable clamping disc (202). A strip hole is opened on the mounting tube (1) for the connector to pass through and slide along the axial direction.

3. The thread loosening mechanism of a flat sewing machine according to claim 1, characterized in that: The movable ring (5) has several ball grooves along its circumference at one end near the wire clamp (2), and each ball groove is fitted with a ball (10).

4. The thread loosening mechanism of a flat sewing machine according to claim 1, characterized in that: The fixed sleeve (4) is fixed with a retaining ring (11) at one end away from the wire clamp (2), and the outer diameter of the retaining ring (11) is larger than the outer diameter of the movable ring (5); The retaining ring (11) has an annular magnet (12) embedded at one end near the movable ring (5), and the movable ring (5) has an annular magnet (13) fixed at one end near the retaining ring (11) to cooperate with the annular magnet (12).

5. The thread loosening mechanism of a flat sewing machine according to claim 1, characterized in that: The inner peripheral wall of the movable ring (5) is provided with several guide grooves along the circumferential direction, and each guide groove extends along the axial direction of the movable ring (5); the outer peripheral wall of the fixed sleeve (4) is fixed with guide ribs (14) corresponding to each guide groove.

6. The thread loosening mechanism of a flat sewing machine according to claim 1, characterized in that: The guide rod (6) is an external hexagonal rod, and a limit nut (15) is threadedly connected to the end of the guide rod (6).

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