Thread trimming mechanism on sewing machine and sewing machine thereof

Abstract

The utility model relates to sewing machine equipment, and discloses a thread trimming mechanism on a sewing machine and the sewing machine thereof, the thread trimming mechanism comprises a motor, a thread trimming crank, a cutter driving crank shaft and a scissor assembly, the thread trimming crank is arranged on an output shaft of the motor, and a roller is arranged at the outer end part of the thread trimming crank; an extension plate is fastened at one end of the cutter driving crankshaft, a groove is formed in the extension plate, and when the motor rotates reversely, the thread trimming crank is matched with the groove through a roller and drives the cutter driving crankshaft to reset; the other end of the cutter driving crankshaft is connected with the shear assembly in a fastening mode, and a reset element for driving the shear assembly to reset is installed on the cutter driving crankshaft. According to the design, the roller at the outer end part of the thread trimming crank is matched with the groove in the extension plate of the cutter driving crank shaft, so that a set of forced cutter return mechanism independent of the reset element is formed when the motor rotates reversely. Even if the reset element cannot work normally, the scissor assembly can be reset, and the problem that the scissor is stuck due to failure of the reset element is effectively solved.

Description

TECHNICAL FIELD

[0001] The utility model relates to sewing machine equipment especially sewing machine's thread cutting mechanism and sewing machine on it. BACKGROUND

[0002] In the field of sewing equipment technology, the thread cutting mechanism of the sewing machine directly affects the quality and efficiency of the sewing work. In the prior art, for example, the thread cutting mechanism of the sewing machine disclosed in the patent with the application number 202020682187.9 cooperates with the motor, thread cutting driving part, thread cutting crank, transmission assembly, thread cutting driving shaft and cutter assembly to realize the thread cutting function. Under normal working conditions, the motor rotates to drive the thread cutting driving part to move, and then the thread cutting crank swings, the transmission assembly drives the thread cutting driving shaft to swing, and finally the cutter assembly completes the thread cutting action.

[0003] However, this prior art has some problems that cannot be ignored. First, during the thread cutting process, the cooperation between the various transmission components is relatively complex, which produces a lot of noise during operation. This not only destroys the tranquility of the working environment, but also may have a negative impact on the hearing of the operator in the long run. Second, when facing different types of fabrics, especially fabrics with thick and hard texture, or thicker sewing thread, the stability of the thread cutting effect is poor, and the thread is often cut continuously or the edges of the cut thread are irregular, which seriously affects the quality of the sewing products and reduces the production efficiency.

[0004] More importantly, in the resetting link after thread cutting, the thread cutting mechanism also has hidden dangers. The existing thread cutting mechanism relies on the reset element to drive the cutter assembly to reset. Once the reset element fails, such as the elastic reduction or fracture of the reset torsional spring, or the damage or failure of other types of reset elements, the cutter is likely to be stuck. When the cutter is stuck, the cutter assembly cannot be reset smoothly, which not only interrupts the current sewing work, but also may cause the sewing thread to be wound on the cutter assembly or other components, further damaging the equipment, increasing maintenance costs and downtime, and causing great inconvenience to production. In view of these problems existing in the prior art, the industry continues to explore a more optimal thread cutting mechanism design scheme. UTILITY MODEL CONTENTS

[0005] The utility model in the prior art provides a thread cutting mechanism on a sewing machine and a sewing machine.

[0006] In order to solve the above technical problems, the utility model solves them through the following technical solutions:

[0007] The thread cutting mechanism on the sewing machine comprises:

[0008] a motor,

[0009] A wire-cutting crank is mounted on the output shaft of the motor, and a roller is installed at the outer end of the wire-cutting crank.

[0010] The cutter drive crankshaft has an extension plate fixed to one end. The extension plate has a groove. When the motor reverses, the wire cutting crank engages with the groove through the roller and drives the cutter drive crankshaft to reset.

[0011] The other end of the cutter drive crankshaft is fastened to the scissor assembly, and a reset element is installed on the cutter drive crankshaft to drive the scissor assembly to reset.

[0012] Preferably, the wire-cutting crank includes a fastening part and an extension part. The fastening part is locked onto the output shaft of the motor, and the extension part is connected to the fastening part and extends outward. A pin is mounted on the extension part, and a roller is fitted onto the pin and can rotate on it.

[0013] Preferably, the extension plate is provided with an opening groove, and the sidewall of the opening groove is recessed outward to form a groove.

[0014] Preferably, a tangential crank is fixedly attached to one side of the scissor assembly, and the other end of the cutter drive crank shaft is fixedly attached to the tangential crank.

[0015] Preferably, the device also includes a base, and the reset element is a torsion spring. The reset element is mounted on the cutter drive crank shaft, with one end of the reset element abutting against the tangential crank and the other end abutting against the base.

[0016] Preferably, a bushing is fitted on the cutter drive crankshaft, and a reset element is fitted on the bushing.

[0017] Sewing machine, including the thread-cutting mechanism on the sewing machine.

[0018] This utility model, by adopting the above technical solution, has significant technical effects:

[0019] When a common problem in traditional wire cutting mechanisms, the failure of the reset element, causes the blade to jam, this design utilizes the cooperation between the roller at the outer end of the wire cutting crank and the groove on the extension plate of the cutter drive crank shaft. This creates a forced blade return mechanism independent of the reset element when the motor reverses. This allows the scissor assembly to reset even when the reset element malfunctions, effectively solving the blade jamming problem caused by reset element failure and greatly reducing the impact of equipment malfunctions on production.

[0020] This design adds a reliable backup reset mechanism to the thread-cutting mechanism, enhancing the fault tolerance of the entire sewing machine thread-cutting system. Even if the critical reset element malfunctions, the thread-cutting mechanism can still operate normally, increasing the reliability and stability of the equipment, reducing maintenance frequency and difficulty, and giving operators greater confidence in the machine's operation. Attached Figure Description

[0021] Figure 1 This is a structural diagram of the present invention without the mounting base.

[0022] Figure 2 This is a schematic diagram of the combined structure of the cutter drive crankshaft and the extension plate.

[0023] Figure 3 This is a schematic diagram of the wire shear crank.

[0024] Figure 4 This is a schematic diagram of the structure of this utility model with the base installed.

[0025] The names of the body parts referred to by the numbers in the above attached diagrams are as follows:

[0026] 1—Motor, 2—Wire cutting crank, 3—Cutter drive crankshaft, 4—Extension plate, 5—Scissors assembly, 6—Reset element, 7—Wire cutting crank, 8—Base, 9—Busset

[0027] 21—Roller, 22—Fastening part, 23—Extension part, 24—Pin shaft

[0028] 41—Groove, 42—Open groove Detailed Implementation

[0029] The following is in conjunction with the appendix Figures 1-4 The present invention will be further described in detail with reference to the embodiments.

[0030] Example 1

[0031] The thread-cutting mechanism on a sewing machine includes:

[0032] Motor 1,

[0033] A wire-cutting crank 2 is mounted on the output shaft of motor 1 by a set screw, and a roller 21 is mounted on the outer end of the wire-cutting crank 2.

[0034] The cutter drive crankshaft 3 has one end fastened to the extension plate 4 by screws. In other embodiments, the extension plate 4 can also be welded to the cutter drive crankshaft 3. The extension plate 4 has a groove 41. When the reset element 6 fails, the wire cutting mechanism will start to force the blade to return. When the motor 1 reverses, the wire cutting crank 2 cooperates with the groove 41 through the roller 21 and drives the cutter drive crankshaft 3 to reset, so that the wire cutting mechanism resets in time after completing the wire cutting.

[0035] The other end of the cutter drive crankshaft 3 is fastened to the scissor assembly 5. The cutter drive crankshaft 3 can drive the scissor assembly 5 to move, realizing the function of cutting the thread. A reset element 6 is installed on the cutter drive crankshaft 3 to drive the scissor assembly 5 to reset. The reset element 6 is a torsion spring. In other embodiments, the reset element 6 can also be a tension spring or a spring sheet. The reset element 6 can enable the scissor assembly 5 to reset in time after cutting the thread.

[0036] Working principle: When cutting the thread, the motor (1) starts running, and its output shaft drives the thread-cutting crank (2) connected to it by a set screw to rotate. The roller (21) at the outer end of the thread-cutting crank (2) moves accordingly. The roller (21) acts on the extension plate (4). As the thread-cutting crank (2) continues to rotate, the movement of the roller (21) drives the extension plate (4), which in turn drives the cutter drive crankshaft (3) to rotate. The cutter drive crankshaft (3) drives the scissor assembly (5) that is fastened to it to move, realizing the thread-cutting function.

[0037] When the wire cutting is completed, under normal circumstances, the reset element (6) installed on the cutter drive crank shaft (3) will function to drive the scissor assembly (5) to reset in time. If the reset element (6) fails, the wire cutting mechanism will activate the forced return mechanism, the motor (1) will reverse, the wire cutting crank (2) will follow the reverse, and the roller (21) at its outer end will cooperate with the groove (41) on the extension plate (4) to drive the cutter drive crank shaft (3) to rotate in the opposite direction, thereby resetting the scissor assembly (5).

[0038] The wire-cutting crank 2 includes a fastening part 22 and an extension part 23. The fastening part 22 is locked to the output shaft of the motor 1 by screws. The extension part 23 is connected to the fastening part 22 and extends outward. The extension part 23 is integrally formed on the fastening part 22. A pin 24 is mounted on the extension part 23. The pin 24 is a shaft screw. The roller 21 is mounted on the pin 24 and can rotate on it. During the process of the wire-cutting crank 2 driving the roller 21 to contact and transmit power with the extension plate 4, the rotation of the roller 21 can convert sliding friction into rolling friction. The rolling friction coefficient is relatively small, which can effectively reduce the friction between the roller 21 and the extension plate 4, reduce the wear of components, extend the service life of the roller 21, the extension plate 4 and the entire wire-cutting mechanism, reduce the frequency of equipment maintenance and replacement of parts, and improve the stability of equipment operation.

[0039] The extension plate 4 has an opening slot 42, and the sidewall of the opening slot 42 is recessed outward to form a groove 41. When the reset element 6 fails, the roller 21 on the wire-cutting crank 2 engages with the groove 41 to force the cutter to return to its original position. The special structural design of the groove 41 provides a precise track for the roller 21, allowing it to move stably within the groove 41 when the motor 1 reverses, reliably driving the cutter to reset the crankshaft 3. Compared to other simpler structures, the engagement of the groove 41 and the roller 21 is more stable and efficient during forced cutter return, greatly improving the self-recovery capability of the wire-cutting mechanism in case of failure and reducing the impact of malfunctions such as tool jamming on production.

[0040] A scissor assembly 5 has a tangent crank 7 fastened to one side, and the other end of the cutter drive crank shaft 3 is fastened to the tangent crank 7. The scissor assembly 5 and the cutter drive crank shaft 3 are securely connected via the tangent crank 7. Compared to a direct connection, the tangent crank 7 provides a larger connection area and more fastening points, making the connection between the scissor assembly 5 and the cutter drive crank shaft 3 more robust and reliable. During high-speed operation of the sewing machine and frequent thread-cutting actions, this stable connection effectively prevents loosening or displacement, ensuring stable power transmission, guaranteeing the accuracy and continuity of the thread-cutting action, and improving thread-cutting quality and efficiency.

[0041] The wire-cutting mechanism also includes a base 8 and a torsion spring as the reset element 6. The reset element 6 is mounted on the cutter drive crank shaft 3, with one end abutting against the tangent crank 7 and the other end abutting against the base 8. Using a torsion spring as the reset element 6, mounted on the cutter drive crank shaft 3 with one end abutting against the tangent crank 7 and the other end against the base 8, creates a stable reset torque. After wire cutting, the torsion spring can use its elastic potential energy to push the tangent crank 7, thereby resetting the cutter drive crank shaft 3 and the scissor assembly 5. This ensures that after each wire cut, the scissor assembly 5 accurately returns to its initial position, preparing for the next wire cut and guaranteeing the continuity and efficiency of the wire cutting operation.

[0042] Example 2

[0043] Example 2 is basically the same as Example 1, except that a bushing 9 is fitted on the cutter drive crankshaft 3, and the reset element 6 is fitted on the bushing 9. The bushing 9 provides additional protection for the cutter drive crankshaft 3. During the operation of the wire cutting mechanism, the bushing 9 effectively reduces the direct friction between the reset element 6 and the cutter drive crankshaft 3, preventing wear and scratches on the surface of the cutter drive crankshaft 3 caused by the reset element 6 during long-term extension, contraction, or torsion. This extends the service life of the cutter drive crankshaft 3 and reduces equipment maintenance costs and repair frequency.

[0044] Example 3

[0045] Sewing machine, including the thread-cutting mechanism on the sewing machine.

Claims

1. A thread-cutting mechanism on a sewing machine, characterized in that... include: Motor (1), A wire-cutting crank (2) is mounted on the output shaft of a motor (1), and a roller (21) is mounted on the outer end of the wire-cutting crank (2). The cutter drive crankshaft (3) has an extension plate (4) at one end. The extension plate (4) has a groove (41). When the motor (1) reverses, the wire cutting crank (2) cooperates with the groove (41) through the roller (21) and drives the cutter drive crankshaft (3) to reset. The other end of the scissor assembly (5) is fastened to the scissor assembly (5), and a reset element (6) is installed on the scissor assembly (5) to drive the scissor assembly (5) to reset.

2. The thread-cutting mechanism on a sewing machine according to claim 1, characterized in that: The wire cutter crank (2) includes a fastening part (22) and an extension part (23). The fastening part (22) is locked on the output shaft of the motor (1). The extension part (23) is connected to the fastening part (22) and extends outward. A pin (24) is mounted on the extension part (23). A roller (21) is fitted on the pin (24) and can rotate on it.

3. The thread-cutting mechanism on a sewing machine according to claim 1, characterized in that: An opening groove (42) is provided on the extension plate (4), and the side wall of the opening groove (42) is recessed outward to form a groove (41).

4. The thread-cutting mechanism on a sewing machine according to claim 1, characterized in that: The scissor assembly (5) is fixedly attached to a tangential crank (7) on one side, and the other end of the cutter drive crank shaft (3) is fixedly attached to the tangential crank (7).

5. The thread-cutting mechanism on a sewing machine according to claim 4, characterized in that: It also includes a base (8), and the reset element (6) is a torsion spring. The reset element (6) is mounted on the cutter drive crank shaft (3). One end of the reset element (6) abuts against the tangent crank (7), and the other end abuts against the base (8).

6. The thread-cutting mechanism on a sewing machine according to any one of claims 1-5, characterized in that: A bushing (9) is fitted on the cutter drive crankshaft (3), and a reset element (6) is fitted on the bushing (9).

7. A sewing machine, characterized in that: Includes the thread-cutting mechanism on the sewing machine as described in any one of claims 1-6.

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