A feeding and cutting mechanism for thread cutting effect of short thread end and sewing machine

Abstract

The application provides a feeding and thread cutting mechanism with short thread end cutting effect and a sewing machine. The feeding and thread cutting mechanism comprises a feeding and thread cutting driving source, a feeding mechanism and a thread cutting mechanism. The feeding mechanism comprises a tooth frame, feeding teeth, a driving crank, a feeding connecting rod and a feeding transmission assembly. The driving crank has a feeding arm, the feeding arm is rotationally connected with the feeding connecting rod, and the feeding transmission assembly is transmissionally connected between the feeding connecting rod and the feeding connecting part of the tooth frame. When the feeding arm is collinear with the feeding connecting rod, the angle of the feeding arm is When the angle of the feeding arm is within the range, the sewing machine has a small needle distance. When the feeding and thread cutting driving source drives the driving crank to rotate, the angle of the feeding arm has a feeding working area and a thread cutting working area, and the thread cutting working area is within the range. When cutting the thread, the feeding and thread cutting driving source drives the feeding arm to operate in the thread cutting working area, the thread cutting mechanism performs a thread cutting action, and the feeding teeth have a very small moving distance in the front and back directions, so that the thread cutting effect of short thread end is realized.

Description

Technical Field

[0001] This invention relates to the field of sewing machine technology, and in particular to a feeding and thread-cutting mechanism for short thread trimming, and a sewing machine incorporating the feeding and thread-cutting mechanism. Background Technology

[0002] Currently, all major sewing machine companies have their own design platforms. The feeding mechanism, the feed dog mechanism, the thread cutting mechanism, and the presser foot lifting mechanism are important functional mechanisms of a sewing machine. Once a company's design platform is determined, the development of its products and the next generation of products are all based on iterative updates of this design platform, and it is almost impossible to research and develop another completely new design platform.

[0003] For example, the drive mechanism of a flat sewing machine disclosed in Chinese Utility Model Patent Application No. 201220297729.6 drives the lifting tooth shaft and the feeding shaft through a main shaft (i.e., the upper shaft). The main shaft is driven by a main motor. The lifting tooth shaft drives the tooth holder and the feeding tooth to move up and down reciprocally through a set of lifting tooth components to perform the lifting action. The feeding shaft drives the tooth holder and the feeding tooth to move back and forth reciprocally through a set of feeding components to perform the feeding action. At the same time, the main shaft also drives the lower shaft to rotate through a set of synchronous belt pulley mechanisms. The lower shaft drives the rotary hook mechanism to rotate and perform the thread hooking action. Furthermore, the sewing machine can also be equipped with a thread cutting mechanism. For example, an automatic thread cutting mechanism disclosed in Chinese Invention Patent Application No. 201710215982.X, when thread cutting is required, the thread cutting drive source is activated, causing the thread cutting ball to contact the thread cutting cam fixed on the lower shaft. Then, the rotation of the lower shaft drives the thread cutting component to rotate and perform the automatic thread cutting action. Clearly, the feeding mechanism, lifting mechanism, and thread cutting mechanism of this sewing machine are relatively complex, with many parts, a long transmission chain, and a clutch component in the thread cutting mechanism to achieve the thread cutting action.

[0004] For example, Chinese invention patent application number 201210365288.3 discloses a sewing machine in which the lifting mechanism is driven by the main shaft of the sewing machine, the main shaft is driven by a main motor, the feeding mechanism is driven by a single feeding motor, and the clutch of the thread cutting mechanism is also driven by the same feeding motor. During thread cutting, after the feeding motor drives the transmission components in the thread cutting mechanism, the thread cutting assembly is still driven by the thread cutting cam on the lower shaft to perform the automatic thread cutting action. Clearly, this sewing machine structure is complex, especially given the use of a grooved cam structure, which is difficult to implement. Furthermore, during thread cutting, it still relies on the main motor driving the main shaft to rotate → the main shaft driving the lower shaft to rotate → the lower shaft driving the thread cutting cam to rotate, thus completing the thread cutting action.

[0005] For example, Chinese utility model patent application number 201520782770.6 discloses a thread-cutting and presser foot-lifting device for a sewing machine. A stepper motor drives both the thread-cutting and presser foot-lifting mechanisms through a complex system. However, because the final execution ends (moving and stationary blades) of the thread-cutting mechanism are located at the left end of the base plate, and the final execution end (presser foot) of the presser foot-lifting mechanism is located at the machine head, the span between the stepper motor and the moving blade, and between the stepper motor and the presser foot, is large. This results in a long overall transmission chain for the sewing machine, causing the stepper motor and transmission structure to occupy most of the installation space within the base plate, thus interfering with the arrangement and installation of other transmission structures in the sewing machine.

[0006] For example, Chinese utility model patent application number 202120273965.3 discloses a sewing machine with a positioning feed dog stop position. It uses a stepper motor to drive a swing seat to rotate, placing the swing seat at different position angles, with each angle corresponding to a different stitch length. Simultaneously, the stepper motor drives the thread-cutting fork wheel and other thread-cutting components via a thread-cutting crank wheel to perform the thread-cutting action. However, this sewing machine structure has a large number of parts, a long transmission chain, poor structural stability, and complex transmission mechanisms for stitch length adjustment and thread-cutting drive. Furthermore, it uses a slotted cam structure, which is difficult to implement.

[0007] In summary, existing sewing machines have the following problems: 1. Complex structure, resulting in poor stability and difficulty in implementation; 2. Long transmission chain, causing the transmission structure, including the stepper motor, to occupy most of the machine's installation space, interfering with the layout and installation of other structures; 3. Relatively simple function, the power of the thread cutting mechanism still depends on the main shaft, or in other words, it still depends on the main motor, and the power source configured in the thread cutting mechanism can only realize the switching of the thread cutting clutch. 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 feeding and cutting mechanism for short thread ends, which uses a power source that can directly drive the cutting and achieve the effect of cutting short thread ends.

[0009] To achieve the above objectives, the present invention provides a feeding and cutting mechanism for short thread trimming, comprising a feeding and cutting drive source, a feeding mechanism, and a cutting mechanism;

[0010] The feeding mechanism includes a toothed frame, a feeding tooth fixed on the toothed frame, a drive crank driven to rotate by a feeding wire shearing drive source, a feeding connecting rod, and a feeding transmission assembly. A feeding arm extends from the drive crank and is rotatably connected to the feeding connecting rod. The feeding transmission assembly is drively connected between the feeding connecting part of the feeding connecting rod and the toothed frame.

[0011] When the feeding arm and the feeding connecting rod are collinear, the angle of the feeding arm is: When the angle of the feed arm is Within this range, the sewing machine has a small stitch pitch;

[0012] The wire cutting mechanism includes a movable blade, a wire cutting arm extending from a drive crank, a wire cutting shaft rotatable about its own axis, a wire cutting clutch assembly, and a wire cutting transmission assembly. The wire cutting clutch assembly is driven between the wire cutting arm and the wire cutting shaft, and the wire cutting transmission assembly is driven between the wire cutting shaft and the movable blade.

[0013] During the process of the feeding and wire-cutting drive source driving the drive crank to rotate, the angle of the feeding arm has mutually independent feeding working area and wire-cutting working area, and the wire-cutting working area is in Within this range: when the feeding arm is operating within the feeding working area, the sewing machine has an effective stitch length, and the thread cutting clutch assembly is in a disengaged state; when the feeding arm is operating within the thread cutting working area, the thread cutting clutch assembly is in an engaged state.

[0014] Furthermore, when the angle of the feeding arm is at Within this range, the feed shearing drive source causes the feed teeth to move no more than 1 mm in the front-to-back direction.

[0015] Furthermore, the feeding and cutting drive source is a drive motor, and the drive crank is fixed on the motor shaft of the drive motor.

[0016] Furthermore, the effective length of the feeding arm is less than the effective length of the feeding connecting rod; the feeding transmission assembly includes a feeding shaft that can rotate around its own axis, a feeding crank fixed to one end of the feeding shaft, and a toothed bracket seat fixed to the other end of the feeding shaft. The feeding crank is rotatably connected to the feeding connecting rod, and the toothed bracket seat is connected to the feeding connection part of the toothed bracket.

[0017] Furthermore, the effective length of the feeding arm is greater than the effective length of the feeding connecting rod; the feeding transmission assembly includes a feeding shaft that can rotate around its own axis, a toothed bracket seat fixed on the feeding shaft, and a feeding connecting arm fixedly connected to the toothed bracket seat. The feeding connecting arm is rotatably connected to the feeding connecting rod, and the toothed bracket seat is connected to the feeding connecting part of the toothed bracket.

[0018] Furthermore, the wire cutting clutch assembly includes a wire cutting ball rotatably mounted on the wire cutting arm and a wire cutting drive component fixed on the wire cutting shaft, wherein a wire cutting drive arm extends from the wire cutting drive component.

[0019] When the feeding arm operates in the feeding working area, the wire cutting ball separates from the wire cutting groove surface on the wire cutting drive arm;

[0020] When the feeding arm operates in the wire cutting working area, the wire cutting ball contacts and engages with the wire cutting groove surface on the wire cutting drive arm.

[0021] Furthermore, the wire cutting mechanism is a single-moving-blade structure, and the wire cutting mechanism also includes a fixed blade. The wire cutting transmission assembly includes a wire cutting crank, a wire cutting connecting rod, and a rotatable moving blade holder, all fixed on the wire cutting shaft. The two ends of the wire cutting connecting rod are respectively hinged to the wire cutting crank and the moving blade holder, and the moving blade is fixed on the moving blade holder.

[0022] Furthermore, the wire cutting mechanism is a single-moving blade structure, and the wire cutting mechanism also includes a fixed blade. A wire cutting connecting arm extends from the wire cutting drive component. The wire cutting transmission assembly includes a wire cutting connecting rod and a rotatable moving blade holder. The two ends of the wire cutting connecting rod are respectively hinged to the wire cutting connecting arm and the moving blade holder, and the moving blade is fixed on the moving blade holder.

[0023] This application also provides a sewing machine equipped with the thread feeding and cutting mechanism described above.

[0024] As described above, the feeding and thread-cutting mechanism and sewing machine with short thread trimming effect of the present invention have the following beneficial effects:

[0025] During wire cutting, the feeding and cutting drive source drives the feeding arm to operate within the wire cutting working area. The wire cutting mechanism performs automatic wire cutting action, and the feeding teeth move very little in the front-to-back direction, achieving the effect of cutting short wire ends. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the feeding and wire cutting mechanism in this application.

[0027] Figure 2 for Figure 1 An exploded view of the integrated mounting base, which is omitted from the diagram.

[0028] Figure 3 for Figure 1 The left view of the figure omits the integrated mounting base.

[0029] Figure 4 This is a schematic diagram showing the distribution of the working area of ​​the feeding arm in Embodiment 1 of the feeding and wire cutting mechanism.

[0030] Figure 5 This is a schematic diagram of the wire cutting clutch assembly in the disengaged state in Embodiment 1 of the wire feeding and cutting mechanism.

[0031] Figure 6 This is a schematic diagram of the wire cutting clutch assembly in the engaged state in Embodiment 1 of the wire feeding and cutting mechanism.

[0032] Figures 7a to 7dThis is a schematic diagram of the four motion trajectories of the feeding teeth in Embodiment 1 of the feeding and wire cutting mechanism.

[0033] Figure 8 This is a schematic diagram showing the position of the feeding arm and the feeding connecting rod collinear in Embodiment 1 of the feeding and wire cutting mechanism.

[0034] Figure 9a to Figure 9c This is a schematic diagram showing three distributions of the wire cutting working area of ​​the feeding arm in Embodiment 1 of the wire cutting mechanism.

[0035] Figure 10 This is a schematic diagram of the structure of Embodiment 2 of the feeding and wire cutting mechanism in this application.

[0036] Figure 11 for Figure 10 The left view.

[0037] Figure 12 This is a schematic diagram showing the connection between the feeding and cutting drive source and the feeding mechanism in Embodiment 2 of the feeding and cutting mechanism.

[0038] Figure 13 This is a schematic diagram showing the connection between the feeding and cutting drive source and the cutting mechanism in Embodiment 2 of the feeding and cutting mechanism.

[0039] Figure 14 This is a schematic diagram showing the distribution of the working area of ​​the feeding arm in Embodiment 2 of the feeding and wire cutting mechanism.

[0040] Figure 15 This is a schematic diagram of the wire cutting clutch assembly in the engaged state in Embodiment 2 of the wire feeding and cutting mechanism.

[0041] Figures 16a to 16d This is a schematic diagram of the four motion trajectories of the feeding teeth in Embodiment 2 of the feeding and wire cutting mechanism.

[0042] Figure 17 This is a schematic diagram showing the position of the feeding arm and the feeding connecting rod collinear in Embodiment 2 of the feeding and wire cutting mechanism.

[0043] Figures 18a to 18c This is a schematic diagram showing three distributions of the wire cutting working area of ​​the feeding arm in Embodiment 2 of the wire cutting mechanism.

[0044] Figure 19 This is a schematic diagram showing the distribution of the feeding and thread-cutting mechanism in the sewing machine according to Embodiment 1 of this application.

[0045] Figure 20 This is a schematic diagram of the structure of the sewing machine in Embodiment 1 of this application.

[0046] Figure 21 This is a schematic diagram of the structure of the sewing machine in Embodiment 2 of this application.

[0047] Component designation explanation

[0048] 10 Integrated mounting base

[0049] 101 Install motherboard

[0050] 102 Motor mounting plate

[0051] 103 Feeding Support Section

[0052] 104 Wire Cutting Support

[0053] 20 Feeding and cutting line drive source

[0054] 21 Drive motor

[0055] 30 Feeding mechanism

[0056] 31 Dental frame

[0057] 311 Feeding Connection Section

[0058] 312 Tooth-lifting connection

[0059] 32 feed dog

[0060] 33 Drive crank

[0061] 331 Feeding arm

[0062] 332 Wire Cutting Arm

[0063] 34 Feeding Link

[0064] 35 Feeding shaft

[0065] 36 Feed Crank

[0066] 37 Dental bracket

[0067] 371 Feeding Connecting Arm

[0068] 40 Wire cutting mechanism

[0069] 41. Cutting

[0070] 42 Thread cutter spool

[0071] 43 Wire-cutting ball bearing

[0072] 44 Wire cutting drive unit

[0073] 441 Wire Cutting Drive Arm

[0074] 442 Wire Cutting Connector Arm

[0075] 443 Reset Arm

[0076] 45 Fixed tool

[0077] 46 Wire-cutting crank

[0078] 47. Wire-cutting connecting rod

[0079] 48. Moving tool holder

[0080] 49. Return torsion spring

[0081] 50 Tooth Lifting Mechanism

[0082] 51 Spindle

[0083] 52 Tooth-lifting shaft

[0084] 53 Eccentric tooth lifting wheel

[0085] 54. Crank handle for lifting teeth

[0086] 55. Tooth-lifting linkage

[0087] 56. Lifting tooth fork-shaped crank

[0088] 57 Tooth-lifting slider

[0089] 58 Drive pulley

[0090] 59 Driven pulley

[0091] 510 Transmission Belt

[0092] 60 base plate Detailed Implementation

[0093] 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.

[0094] 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.

[0095] This application provides a thread feeding and trimming mechanism for short thread trimming, and a sewing machine including the thread feeding and trimming mechanism. For ease of description, in the following embodiments, the directions are defined as follows: the length direction of the sewing machine is defined as the left-right direction, and the direction towards the head of the sewing machine is the left direction, and the direction towards the tail of the sewing machine is the right direction. The left-right direction is also the axial direction of the main shaft 51 in the sewing machine; the height direction of the sewing machine is defined as the up-down direction, the width direction of the sewing machine is defined as the front-back direction, and the direction of fabric movement when the sewing machine is sewing forward is the front direction.

[0096] like Figures 1 to 3 As shown, the short thread trimming mechanism involved in this application includes a feeding and trimming drive source 20, a feeding mechanism 30, and a trimming mechanism 40. The feeding mechanism 30 includes a toothed frame 31, feeding teeth 32 fixed to the upper surface of the toothed frame 31, a drive crank 33 driven to rotate by the feeding and trimming drive source 20, a feeding connecting rod 34, and a feeding transmission assembly. The front end of the toothed frame 31 is a feeding connection part 311, and the rear end of the toothed frame 31 is a tooth lifting connection part 312. A feeding arm 331 extends from the drive crank 33 and is rotatably connected to the feeding connecting rod 34. The feeding transmission assembly is driveably connected between the feeding connecting rod 34 and the feeding connection part 311 of the toothed frame 31. Specifically, as shown... Figure 8 As shown, when the feeding arm 331 and the feeding connecting rod 34 are collinear, the angle of the feeding arm 331 at this time is denoted as . When the angle of the feed arm 331 is at Within this range, the sewing machine has a small stitch pitch, meaning the amount of movement of the feed teeth 32 driven by the feed and thread-cutting drive source 20 is relatively small. The thread-cutting mechanism 40 includes a movable blade 41, a thread-cutting arm 332 driven to rotate by the feed and thread-cutting drive source 20, a thread-cutting shaft 42 rotatable about its own axis, a thread-cutting clutch assembly, and a thread-cutting transmission assembly. The thread-cutting clutch assembly is driven between the thread-cutting arm 332 and the thread-cutting shaft 42, and the thread-cutting transmission assembly is driven between the thread-cutting shaft 42 and the movable blade 41.

[0097] Preferably, the feeding and wire-cutting drive source 20 is a drive motor 21, and the drive crank 33 is fixed to the motor shaft of the drive motor 21 by screws or other fasteners; the drive motor 21 is preferably a stepper motor. Furthermore, both the wire-cutting arm 332 and the drive crank 33 are driven to rotate by the feeding and wire-cutting drive source 20. The wire-cutting arm 332 and the drive crank 33 can be separate components, both fixed to the motor shaft of the modular drive source 20 by screws, or the wire-cutting arm 332 can be fixed to the drive crank 33. In the following embodiments, the wire-cutting arm 332 extends integrally from the outer circumference of the drive crank 33.

[0098] During the process of drive motor 21 driving drive crank 33 to rotate, such as Figure 4As shown, the feeding arm 331 has an independent feeding working area X1 and a wire cutting working area X2. The two ends of the feeding working area X1 have angles of respectively... and The angles at both ends of the wire-cutting work area X2 are respectively and The wire cutting work area X2 is set in Within this range; along the forward rotation direction of the drive motor 21 when the sewing machine cuts the thread, Thus, the angular range of the feeding working area X1 of the feeding arm 331 is... The angle range of the wire cutting working area X2 of the feeding arm 331 is: Furthermore, the feeding arm 331 also has an idle area X3 distributed between the feeding working area X1 and the wire cutting working area X2, and the angle range of the idle area X3 of the feeding arm 331 is as follows:

[0099] During normal sewing, the feed and thread-cutting drive source 20 drives the drive crank 30 to rotate, and the feed arm 331 rotates together with the drive crank 30. When the feed and thread-cutting drive source 20 drives the feed arm 331 of the drive crank 33 to operate within the feed working area X1, the feed arm 331 drives the feed tooth 31 to move back and forth through the feed connecting rod 34 and the feed transmission assembly. The feed tooth 32 moves back and forth synchronously with the feed tooth 31 to perform the feed action. The sewing machine has an effective stitch length, which includes a positive stitch length corresponding to the forward sewing state and a negative stitch length corresponding to the reverse sewing state. The thread-cutting clutch assembly is in a disengaged state and does not transmit force to the thread-cutting transmission assembly, so the thread-cutting mechanism 40 does not perform the thread-cutting action.

[0100] When the sewing machine needs to trim the thread, the feeding and trimming drive source 20 drives the feeding arm 331 to rotate clockwise from the current angle in the feeding work area X1 to the starting angle in the trimming work area X2. Then, continue rotating forward to the endpoint angle of the wire cutting work area X2. From the feed arm 331 Turning to During this process, when the feeding arm 331 is running in the wire cutting working area X2, the wire cutting clutch assembly is in the engaged state. The feeding and wire cutting drive source 20 drives the moving blade 41 to move in sequence through the drive crank 33, the wire cutting clutch assembly, the wire cutting shaft 42 and the wire cutting transmission assembly, and then the wire cutting mechanism 40 performs automatic wire cutting action.

[0101] Therefore, the feeding and thread-cutting mechanism involved in this application uses the same drive motor 21 to simultaneously drive feeding and thread cutting, and the feeding drive and thread-cutting drive do not conflict with each other. During thread cutting, the power for cutting comes directly from the drive motor 21, without relying on other power sources in the sewing machine. This results in a simple and compact structure, a short transmission chain, ease of implementation, and good operational stability. In particular, the thread-cutting working area X2 is set in... Within this range, when the wire cutting drive source 20 drives the feed arm 331 of the drive crank 33 to operate within the wire cutting working area X2, the amount of movement of the drive crank 33 in the reciprocating motion of the toothed frame 31 through the feed connecting rod 34 and the feed transmission assembly is very small, that is, the amount of forward feeding is very small, thereby stably achieving the wire cutting effect of short wire ends and improving the customer experience.

[0102] Furthermore, such as Figure 1 As shown, the sewing machine also includes an integrated mounting base 10. The feed and thread-cutting drive source 20 is independent of the other drive sources in the sewing machine. The feed and thread-cutting drive source 20, the feed mechanism 30, and the thread-cutting mechanism 40 are all mounted on the integrated mounting base 10. Thus, the integrated mounting base 10, the feed and thread-cutting drive source 20, the feed mechanism 30, and the thread-cutting mechanism 40 are integrated into an independent functional module, defined as an independent feed and thread-cutting module. This independent feed and thread-cutting module integrates the feed function and the automatic thread-cutting function. The feed mechanism 30 and the thread-cutting mechanism 40 are modularized independently, making them independent of other functional mechanisms in the sewing machine. Using an independent feed and thread-cutting drive source 20 to drive the feed and thread-cutting independently, the power source for the feed and thread-cutting does not depend on other functional mechanisms in the sewing machine, thereby simplifying the structure of the feed mechanism 30 and the thread-cutting mechanism 40, effectively shortening their respective transmission chains, reducing space occupation, and minimizing interference with the installation and arrangement of other functional mechanisms in the sewing machine. Furthermore, by integrating and removing the mounting base 10 in the sewing machine, the independent feeding and thread cutting module can be installed and removed as a whole in the sewing machine. This allows the independent feeding and thread cutting module to be quickly adapted and installed in various sewing machine models, demonstrating strong compatibility. In other words, this application has developed a novel design platform for sewing machines.

[0103] Furthermore, the feeding and wire cutting mechanism involved in this application has multiple different embodiments due to the different structures of the feeding transmission assembly, the wire cutting clutch assembly, and the wire cutting transmission assembly. Two preferred embodiments of the feeding and wire cutting mechanism are provided below.

[0104] Example 1 of feeding and wire cutting mechanism

[0105] like Figures 1 to 3As shown, the integrated mounting base 10 has a horizontally arranged mounting main board 101 and a motor mounting plate 102 extending vertically from the right end of the mounting main board 101. The mounting main board 101 is fixed to the bottom of the sewing machine base plate 60 by fasteners such as screws. The drive motor 21 is fixed to the right side of the motor mounting plate 102 by fasteners such as screws. The motor shaft of the drive motor 21 passes through the motor mounting plate 102.

[0106] Furthermore, such as Figures 1 to 3 As shown, the feeding transmission assembly includes a feeding shaft 35 that can rotate around its own axis and extends axially to the left and right, a feeding crank 36 fixed to the right end of the feeding shaft 35, and a toothed bracket seat 37 fixed to the left end of the feeding shaft 35. The feeding crank 36 is rotatably connected to the feeding connecting rod 34, i.e., hinged. The toothed bracket seat 37 is connected to the feeding connection part 311 of the toothed bracket 31. The effective length of the feeding arm 331 is less than the effective length of the feeding connecting rod 34, i.e., the feeding wire cutting mechanism in Embodiment 1 adopts a short crank-long connecting rod structure. The effective length of the feeding arm 331 refers to the distance between the center of the motor shaft of the drive motor 21 and the rotation center of the feeding arm 331 and the feeding connecting rod 34; the effective length of the feeding connecting rod 34 refers to the distance between the rotation center of the feeding arm 331 and the feeding connecting rod 34 and the rotation center of the feeding connecting rod 34 and the feeding crank 36.

[0107] When the drive motor 21 drives the feed arm 331 of the drive crank 33 to rotate within the feed working area X1, the feed arm 331 drives the feed crank 36 to swing via the feed connecting rod 34. The feed shaft 35 and the tooth holder 37 swing together with the feed crank 36, thereby driving the tooth holder 31 and the feed tooth 32 to move back and forth reciprocally for feeding. By adjusting the swing angle range of the drive motor 21, the swing range of the feed arm 331 of the drive crank 33 within the feed working area X1 is adjusted, thereby adjusting the effective stitch length of the sewing machine, realizing the adjustment of the feed stitch length, and thus adjusting the movement trajectory of the feed tooth 32. For example, the feed tooth 32 can have the following characteristics: Figure 7a The elliptical motion trajectory shown, or making the feed tooth 32 have such... Figure 7b The near-vertical motion trajectory shown, or making the feed tooth 32 have a shape like... Figure 7c The shown far-vertical motion trajectory, or making the feed tooth 32 have such a Figure 7d The rectangular motion trajectory is shown. Thus, the feeding and thread-cutting mechanism in Embodiment 1 has functions such as step-adjusting stitch length, backstitch switching, feeding trajectory switching, and pattern stitching.

[0108] Furthermore, such as Figure 8As shown, circle O1 is drawn with the rotation center C of the feeding arm 331 as the center and the effective length CD of the feeding arm 331 as the radius. Point C is also the center of the motor shaft of the drive motor 21, and point D is the rotation center of the feeding arm 331 and the feeding connecting rod 34. Circle O2 is drawn with the hinge point B of the feeding connecting rod 34 and the feeding crank 36 as the center and the effective length BD of the feeding connecting rod 34 as the radius. Point A is the center of the feeding shaft 35. Circles O1 and O2 are basically coincident within an angle range of ±β on both sides of the collinear position of the feeding arm 331 and the feeding connecting rod 34. Let the angle of the feeding arm 331 when the feeding arm 331 and the feeding connecting rod 34 are collinear be denoted as . Then the feeding arm 331 is in During movement within this range, the feed crank 36 remains essentially stationary, meaning the displacement of the feed tooth 32 in the forward and backward directions is very small, and there is essentially no feeding. That is, when the angle of the feed arm 331 is within... Within this range, the sewing machine has a small stitch pitch; in this embodiment, when the angle of the feed arm 331 is within... Within this range, the movement of the feed tooth 32 in the front-to-back direction does not exceed 1 mm. Based on this, the wire-cutting working area X2 of the feed arm 331 is set at... Within this range, the movement distance of the feed tooth 32 in the front-to-back direction during the wire cutting process is very small; therefore, the wire cutting working area X2 of the feed arm 331 can be set as follows: Thus, the wire-cutting working area X2 of the feeding arm 331 can have the following three embodiments.

[0109] Example 1 of the wire cutting work area X2 of the feeding arm 331, as shown in Figure 9a.

[0110] Example 2: The wire-cutting work area X2 of the feeding arm 331 is shown in Figure 9b.

[0111] Example 3: Wire cutting work area X2 of feeding arm 331 Figure 9c As shown,

[0112] Furthermore, when the feeding arm 331 and the feeding link 34 are collinear, the feeding tooth 32 is located at the front limit position within its reciprocating range, thus the feeding tooth 32 has a minimum limit distance with the front end of the tooth groove of the needle plate. Alternatively, when the feeding arm 331 and the feeding link 34 are collinear, the feeding tooth 32 is located at the rear limit position within its reciprocating range, thus the feeding tooth 32 has a minimum limit distance with the rear end of the tooth groove of the needle plate.

[0113] Preferably, the integrated mounting base 10 further includes a feeding support portion 103 integrally extending from the mounting main board 101. The feeding shaft 35 is rotatably supported in the feeding support portion 103 of the integrated mounting base 10 via bearings, bushings, and other components. In the left-right direction, the feeding crank 36 is distributed on the right side of the feeding support portion 103, and the toothed bracket seat 37 is distributed on the left side of the feeding support portion 103. One end of the feeding connecting rod 34 is rotatably connected to the outer end of the feeding arm 331, and the other end of the feeding connecting rod 34 is connected to the feeding crank 36 via axially extending pins and bearings, i.e., hinged. The bearings are assembled between the pins and the ends of the feeding connecting rod 34.

[0114] Furthermore, such as Figures 1 to 3 As shown, the wire-cutting arm 332 on the drive crank 33 is circumferentially offset from the feeding arm 331. The integrated mounting base 10 also includes a wire-cutting support portion 104 integrally extended from the mounting main board 101. The wire-cutting shaft 42 is rotatably supported in the wire-cutting support portion 104 of the integrated mounting base 10 through bearings, bushings, and other components. The wire-cutting clutch assembly includes a wire-cutting ball 43 and a wire-cutting drive member 44 fixed to the right end of the wire-cutting shaft 42. A wire-cutting drive arm 441 extends from the wire-cutting drive member 44. The wire-cutting ball 43 is rotatably mounted on the wire-cutting arm 332, and the wire-cutting drive arm 441 is provided with a wire-cutting groove surface. Alternatively, the wire-cutting ball 43 is rotatably mounted on the wire-cutting drive arm 441, and the wire-cutting arm 332 is provided with a wire-cutting groove surface. In this embodiment, the wire-cutting ball 43 is rotatably mounted on the wire-cutting arm 332, and the outer peripheral surface of the wire-cutting drive arm 441 has a section of wire-cutting groove surface. When the feeding arm 331 is operating within the feeding work area X1, the feeding tooth 32 feeds normally. At this time, if Figure 5 As shown, the wire-cutting ball 43 separates from the wire-cutting groove surface on the wire-cutting drive arm 441, thus disengaging the wire-cutting clutch assembly and preventing power transmission; therefore, the wire-cutting mechanism 40 does not operate. When wire cutting is required, the drive motor 21 drives the feeding arm 331 to rotate clockwise from the current angle in the feeding working area X1 to the starting angle in the wire-cutting working area X2. Then, continue rotating forward to the endpoint angle of the wire cutting work area X2. From the feed arm 331 Turning to During this process, the feeding arm 331 operates within the wire cutting working area X2, and the wire cutting ball 43 gradually approaches the wire cutting groove surface of the wire cutting drive arm 441 until it makes contact, as... Figure 6As shown, the wire-cutting clutch assembly is engaged, transmitting power. Then, the feeding arm 331 contacts the wire-cutting drive arm 441 via the wire-cutting ball bearing 43, pushing the wire-cutting drive component 44, which in turn drives the wire-cutting shaft 42 to rotate. This, in turn, drives the moving blade 41 through the wire-cutting transmission assembly, and the wire-cutting mechanism 40 performs automatic wire cutting. Of course, in other embodiments, the wire-cutting arm 332 on the drive crank 33 and the feeding arm 331 can overlap circumferentially, thus forming a single arm.

[0115] Preferably, the wire cutting mechanism 40 can be a single-moving blade structure or a double-moving blade structure. In Embodiment 1 of the feeding and wire cutting mechanism, as shown... Figure 1 and Figure 2 As shown, the wire cutting mechanism 40 is a single-moving-blade structure. The wire cutting mechanism 40 also includes a fixed blade 45. The wire cutting transmission assembly includes a wire cutting crank 46 fixed on the wire cutting shaft 42, a wire cutting connecting rod 47, and a rotatable moving blade holder 48. The two ends of the wire cutting connecting rod 47 are respectively hinged to the wire cutting crank 46 and the moving blade holder 48. The moving blade 41 is fixed on the moving blade holder 48.

[0116] Preferably, such as Figure 1 and Figure 2 As shown, the wire cutting mechanism 40 also includes a return torsion spring 49 sleeved on the wire cutting shaft 42. The two ends of the return torsion spring 49 are connected to the integrated mounting base 10 and the wire cutting crank 46, respectively. After wire cutting is completed, the drive motor 21 rotates in the reverse direction, driving the feeding arm 331 from the end angle of the wire cutting working area X2. Reversing to the current angle within the feeding work area X1 before wire cutting, the wire cutting crank 46 is driven to reset under the action of the reset torsion spring 49, which in turn drives the wire cutting shaft 42, wire cutting connecting rod 47, moving blade holder 48, and other components to reset respectively; furthermore, when wire cutting is not required, the reset torsion spring 49 also keeps the wire cutting crank 46 in its initial position. More preferably, as Figure 5 and Figure 6 As shown, a reset arm 443 extends from the wire-cutting drive component 44. The reset arm 443 is circumferentially offset from the wire-cutting drive arm 441, and the outer circumferential surface of the reset arm 443 has a forced reset surface. The drive motor 21 drives the feeding arm 331 from the end angle of the wire-cutting working area X2. When the reverse rotation begins, the forced reset surface on the reset arm 443 contacts and engages with the wire cutting ball 43. The wire cutting ball 43 pushes the reset arm 443 to reset, thereby driving the wire cutting drive 44 to reset, which in turn drives all components in the wire cutting mechanism 40 to reset. This avoids the risk that the moving blade 41 will not be able to reset smoothly due to being stuck by the wire, ensuring that the moving blade 41 can get out of the fault position where it is stuck by the wire and ensuring that it can automatically cut the wire smoothly next time.

[0117] Example 2 of the feeding and cutting mechanism

[0118] like Figures 10 to 12 As shown, the feeding transmission assembly includes a feeding shaft 35 that can rotate around its own axis and extends axially to the left and right, a tooth holder seat 37 fixed on the feeding shaft 35, and a feeding connecting arm 371 fixedly connected to the tooth holder seat 37. The feeding shaft 35 is rotatably supported in the integrated mounting base 10. The feeding connecting arm 371 is rotatably connected to the feeding connecting rod 34, i.e., hinged. The tooth holder seat 37 is connected to the feeding connecting part 311 of the tooth holder 31. The effective length of the feeding arm 331 is greater than the effective length of the feeding connecting rod 34, i.e., the feeding wire cutting mechanism adopts a long crank-short connecting rod structure. The effective length of the feeding arm 331 refers to the distance between the center of the motor shaft of the drive motor 21 and the rotation center of the feeding arm 331 and the feeding connecting rod 34; the effective length of the feeding connecting rod 34 refers to the distance between the rotation center of the feeding arm 331 and the feeding connecting rod 34 and the rotation center of the feeding connecting rod 34 and the feeding connecting arm 371. The feeding connecting arm 371 and the tooth holder seat 37 can be an integral structure, in which case the feeding connecting arm 371 is integrally provided on the outer circumference of the tooth holder seat 37; or, the feeding connecting arm 371 and the tooth holder seat 37 are separate parts, and the two are fixedly connected by screws.

[0119] When the drive motor 21 drives the feed arm 331 of the drive crank 33 to rotate within the feed working area X1, the feed arm 331 drives the feed shaft 35 to swing via the feed connecting rod 34, which in turn drives the tooth holder 31 and the feed tooth 32 to reciprocate back and forth via the tooth holder seat 37, allowing the feed tooth 32 to feed normally. By adjusting the swing angle range of the drive motor 21, the swing range of the feed arm 331 of the drive crank 33 within the feed working area X1 is adjusted, thereby adjusting the effective stitch length of the sewing machine, achieving adjustment of the feed stitch length, and thus adjusting the movement trajectory of the feed tooth 32. For example, the feed tooth 32 can have the following characteristics: Figure 16a The elliptical motion trajectory shown, or making the feed tooth 32 have such... Figure 16b The near-vertical motion trajectory shown, or making the feed tooth 32 have a shape like... Figure 16c The shown far-vertical motion trajectory, or making the feed tooth 32 have such a Figure 16d The rectangular motion trajectory is shown. Thus, the second embodiment of the feeding and thread-cutting mechanism has functions such as step-adjusting stitch length, backstitch switching, feeding trajectory switching, and pattern stitching.

[0120] like Figure 17As shown, circle O3 is drawn with the rotation center E of the feeding arm 331 as the center and the effective length EF of the feeding arm 331 as the radius. Point E is also the center of the motor shaft of the drive motor 21, and point F is the rotation center of the feeding arm 331 and the feeding connecting rod 34. Circle O4 is drawn with the hinge point G of the feeding connecting rod 34 and the feeding connecting arm 371 as the center and the effective length FG of the feeding connecting rod 34 as the radius. Circles O3 and O4 are basically coincident within a ±β angle range on both sides of the collinear position of the feeding arm 331 and the feeding connecting rod 34. Let the angle of the feeding arm 331 when the feeding arm 331 and the feeding connecting rod 34 are collinear be denoted as . Then the feeding arm 331 is in During movement within this range, the four-bar linkage consisting of the drive crank 33, feed connecting rod 34, tooth holder seat 37, and tooth holder 31 forms an intermittent mechanism, creating a pause period. Specifically, the positional change of the hinge point of the feed connecting arm 371 of the feed connecting rod 34 and tooth holder seat 37 is small, and the positional angle change of the tooth holder seat 37 is small. The tooth holder seat 37 remains essentially stationary, resulting in very small displacement of the feed tooth 32 in the forward and backward direction, essentially no feeding. That is, when the angle of the feed arm 331 is within... Within this range, the sewing machine has a small stitch pitch; in this embodiment, when the angle of the feed arm 331 is within... Within this range, the movement of the feed tooth 32 in the front-to-back direction does not exceed 1 mm. Based on this, the wire-cutting working area X2 of the feed arm 331 is set at... Within this range, the movement distance of the feed tooth 32 in the front-to-back direction during the wire cutting process is very small; therefore, the wire cutting working area X2 of the feed arm 331 can be set as follows: Thus, the wire-cutting working area X2 of the feeding arm 331 can have the following three embodiments.

[0121] Example 1: Wire cutting work area X2 of feeding arm 331 Figure 18a As shown,

[0122] Example 2: Wire cutting work area X2 of feeding arm 331 Figure 18b As shown,

[0123] Example 3: Wire cutting work area X2 of feeding arm 331 Figure 18c As shown,

[0124] Furthermore, when the feeding arm 331 and the feeding link 34 are collinear, the feeding tooth 32 is located at the front limit position within its reciprocating range, thus the feeding tooth 32 has a minimum limit distance with the front end of the tooth groove of the needle plate. Alternatively, when the feeding arm 331 and the feeding link 34 are collinear, the feeding tooth 32 is located at the rear limit position within its reciprocating range, thus the feeding tooth 32 has a minimum limit distance with the rear end of the tooth groove of the needle plate.

[0125] like Figure 10 , Figure 11 and Figure 13 As shown, the wire cutting clutch assembly includes a wire cutting ball 43 and a wire cutting drive member 44 fixed on the wire cutting shaft 42. A wire cutting drive arm 441 extends from the wire cutting drive member 44. The wire cutting ball 43 is rotatably mounted on the wire cutting arm 332, and the wire cutting drive arm 441 is provided with a wire cutting groove surface. Alternatively, the wire cutting ball 43 is rotatably mounted on the wire cutting drive arm 441, and the wire cutting arm 332 is provided with a wire cutting groove surface. In this embodiment, the wire cutting ball 43 is rotatably mounted on the wire cutting arm 332, and the outer peripheral surface of the wire cutting drive arm 441 has a wire cutting groove surface. The wire cutting transmission assembly is connected between the wire cutting shaft 42 and the moving blade 41. In this embodiment, the wire-cutting arm 332 and the feeding arm 331 on the drive crank 33 are the same arm. The outer end of this common arm, the feeding connecting rod 34, and the wire-cutting ball 43 are coaxially connected by a left-right extending pin. The feeding connecting rod 34 is distributed on the left side of the common arm, and the wire-cutting ball 43 is distributed on the right side of the common arm. The wire-cutting mechanism 40 is a single-moving-blade structure. The wire-cutting mechanism 40 also includes a fixed blade 45. A wire-cutting connecting arm 442 extends from the wire-cutting drive member 44. The wire-cutting drive arm 441 and the wire-cutting connecting arm 442 are circumferentially staggered. The wire-cutting transmission assembly includes a wire-cutting connecting rod 47 and a rotatable moving blade holder 48. The two ends of the wire-cutting connecting rod 47 are hinged to the wire-cutting connecting arm 442 and the moving blade holder 48, respectively. The moving blade 41 is fixed on the moving blade holder 48. Of course, in other embodiments, the wire-cutting mechanism 40 can also adopt a double-moving-blade structure.

[0126] When the feeding arm 331 operates within the feeding working area X1, the feeding teeth 32 feed normally. At this time, the wire-cutting ball 43 separates from the wire-cutting groove surface on the wire-cutting drive arm 441, thus disengaging the wire-cutting clutch assembly and preventing power transmission; the wire-cutting mechanism 40 does not operate. When wire cutting is required, the drive motor 21 drives the feeding arm 331 to rotate clockwise from the current angle within the feeding working area X1 to the starting angle within the wire-cutting working area X2. Then, continue rotating forward to the endpoint angle of the wire cutting work area X2. From the feed arm 331 Turning to During this process, the feeding arm 331 operates within the wire cutting working area X2, and the wire cutting ball 43 gradually approaches the wire cutting groove surface of the wire cutting drive arm 441 until it makes contact, as... Figure 15 As shown, the wire cutting clutch assembly is in the engaged state and transmits power. Then, the feeding arm 331 contacts and cooperates with the wire cutting groove surface of the wire cutting drive arm 441 through the wire cutting ball 43 to push the wire cutting drive component 44. Then, the moving blade 41 is driven to move through the wire cutting connecting rod 47 and the moving blade holder 48, and the wire cutting mechanism 40 performs automatic wire cutting.

[0127] Furthermore, the wire cutting mechanism 40 also includes a return torsion spring 49 sleeved on the wire cutting shaft 42, with its two ends connected to the integrated mounting base 10 and the wire cutting connecting arm 442, respectively. After wire cutting is completed, the drive motor 21 rotates in the reverse direction, driving the feeding arm 331 from the end angle of the wire cutting working area X2. Reversing to the current angle within the feeding work area X1 before wire cutting, the wire cutting drive 44 is driven to rotate in the opposite direction and reset under the action of the reset torsion spring 49. This also drives the wire cutting shaft 42, wire cutting connecting rod 47, moving blade holder 48, and other components to reset. Furthermore, when wire cutting is not required, the reset torsion spring 49 also keeps the wire cutting drive 44 in its initial position. More preferably, as... Figure 15 As shown, a reset arm 443 extends from the wire-cutting drive component 44. The reset arm 443 is circumferentially offset from the wire-cutting drive arm 441, and the outer circumferential surface of the reset arm 443 has a forced reset surface. The drive motor 21 drives the feeding arm 331 from the end angle of the wire-cutting working area X2. When the reverse rotation begins, the forced reset surface on the reset arm 443 contacts and engages with the wire cutting ball 43. The wire cutting ball 43 pushes the reset arm 443 to reset, thereby driving the wire cutting drive 44 to reset, which in turn drives all components in the wire cutting mechanism 40 to reset. This avoids the risk that the moving blade 41 will not be able to reset smoothly due to being stuck by the wire, ensuring that the moving blade 41 can get out of the fault position where it is stuck by the wire and ensuring that it can automatically cut the wire smoothly next time.

[0128] Furthermore, in the sewing machine involved in this application, such as Figure 19 and Figure 20 ,or Figure 19 and Figure 21As shown, the sewing machine also includes a tooth-lifting mechanism 50, a tooth-lifting drive source, and a fixedly mounted base plate 60. The tooth-lifting mechanism 50 is driven between the tooth-lifting drive source and the tooth-lifting connection part 312 at the rear end of the tooth holder 31. The integrated mounting base 10 is detachably mounted on the bottom of the base plate 60; thus, by installing and removing the integrated mounting base 10 in the sewing machine, the entire feeding and thread-cutting mechanism can be installed and removed from the sewing machine, allowing the feeding and thread-cutting mechanism to be quickly adapted and installed as a separate functional mechanism in various sewing machine models without interfering with other functional mechanisms of the sewing machine, thus exhibiting strong compatibility. Preferably, the integrated mounting base 10 and the base plate 60 are detachably connected by several screws, facilitating easy assembly and disassembly. Figure 19 As shown, the feeding and thread-cutting mechanism is located on the left side of the base plate 60 near the sewing machine head.

[0129] Furthermore, such as Figure 20 or Figure 21 As shown, the tooth-lifting drive source is the main motor of the sewing machine. The tooth-lifting mechanism 50 includes a main shaft 51 driven to rotate by the main motor, a tooth-lifting shaft 52 parallel to the main shaft 51, a first tooth-lifting transmission assembly connected between the main shaft 51 and the tooth-lifting shaft 52, and a second tooth-lifting transmission assembly connected between the tooth-lifting shaft 52 and the tooth-lifting connecting part 312 of the tooth frame 31. Both the main shaft 51 and the tooth-lifting shaft 52 extend axially in the left-right direction.

[0130] When the feeding and cutting mechanism is compatible with the oscillating tooth lifting machine, such as Figure 20 As shown, the first tooth-lifting transmission assembly includes a tooth-lifting eccentric wheel 53 fixed on the main shaft 51, a tooth-lifting crank 54 fixed on the right end of the tooth-lifting shaft 52, and a tooth-lifting connecting rod 55. The upper end of the tooth-lifting connecting rod 55 is rotatably sleeved on the outer circumference of the tooth-lifting eccentric wheel 53, and the lower end of the tooth-lifting connecting rod 55 is hinged to the tooth-lifting crank 54. The second tooth-lifting transmission assembly includes a tooth-lifting fork-shaped crank 56 fixed on the left end of the tooth-lifting shaft 52, and a tooth-lifting slider 57 hinged to the tooth-lifting connection part 312 of the tooth frame 31. The tooth-lifting fork-shaped crank 56 has a tooth-lifting groove that slides with the tooth-lifting slider 57. The main motor drives the main shaft 51 to rotate, and the main shaft 51 drives the tooth-lifting shaft 52 to swing through the first tooth-lifting transmission assembly. The tooth-lifting shaft 52 drives the tooth-lifting fork-shaped crank 56 to swing up and down through the second tooth-lifting transmission assembly, thereby realizing the up and down reciprocating motion of the tooth frame 31 and the feeding tooth 32, and performing the tooth-lifting action. The up-and-down lifting motion of the feed tooth 32 and the forward-and-backward feeding motion together constitute the feeding trajectory of the feed tooth 32. Of course, in other embodiments, the second lifting transmission assembly can adopt a transmission pair with other structures.

[0131] When the feeding and cutting mechanism is compatible with the rotary tooth lifting machine, such as Figure 21As shown, the first tooth-lifting transmission assembly includes a driving pulley 58 fixed on the main shaft 51, a driven pulley 59 fixed on the right end of the tooth-lifting shaft 52, and a transmission belt 510 connecting the outer periphery of the driving pulley 58 and the driven pulley 59. The speed ratio of the driving pulley 58 to the driven pulley 59 is 1:1. The second tooth-lifting transmission assembly includes a tooth-lifting eccentric wheel 53 fixed on the left end of the tooth-lifting shaft 52 and a tooth-lifting connecting rod 55. One end of the tooth-lifting connecting rod 55 is rotatably sleeved on the outer periphery of the tooth-lifting eccentric wheel 53, and the other end of the tooth-lifting connecting rod 55 is hinged to the tooth-lifting connection part 312 of the tooth holder 31. The main motor drives the main shaft 51 to rotate, and the main shaft 51 drives the tooth-lifting shaft 52 to rotate through the first tooth-lifting transmission assembly. The tooth-lifting shaft 52 drives the tooth holder 31 and the feeding tooth 32 to reciprocate up and down through the second tooth-lifting transmission assembly, thus performing the tooth-lifting action. The up-and-down lifting motion of the feed tooth 32 and the forward-and-backward feeding motion together constitute the feeding trajectory of the feed tooth 32. Of course, in other embodiments, the second lifting transmission assembly can adopt a transmission pair with other structures.

[0132] In summary, the feeding and thread-cutting mechanism and sewing machine of the present invention have the following advantages:

[0133] 1. The feed and thread cutting mechanism adopts a modular design, which can be used as an independent unit module to adapt to various types of sewing machine models. It has strong compatibility and has developed a new design platform for sewing machines.

[0134] 2. The independent modular feeding and thread cutting mechanism integrates the feeding mechanism 30 and the thread cutting mechanism 40 into one, which has a simplified structure, short transmission chain, small installation space, and does not interfere with other functional mechanisms of the sewing machine.

[0135] 3. The same drive motor 21 is used for both feeding and wire cutting, and the two do not interfere with each other.

[0136] 4. By adjusting the output angle of the drive motor 21, functions such as stitch length adjustment, backstitch switching, feed dog 32 trajectory switching, and pattern stitching can be realized. It has comprehensive functions and wide adaptability.

[0137] 5. The thread cutting mechanism 40 can be driven by the drive motor 21 to achieve thread cutting without relying on other drive sources in the sewing machine, thus ensuring the independent modularity of the feeding and thread cutting mechanism.

[0138] 6. When the wire cutting mechanism 40 performs the wire cutting action, the feed tooth 32 moves a very small distance in the front and back direction, which can achieve the effect of short wire ends when cutting the wire.

[0139] In summary, this invention effectively overcomes the various shortcomings of the prior art and has high industrial application value.

[0140] 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 short stub end thread trimming effect thread feeding and trimming mechanism, characterized in that: The feeding and thread cutting driving source (20), the feeding mechanism (30) and the thread cutting mechanism (40) are included. The feeding mechanism (30) includes a rack (31), feeding teeth (32) fixed on the rack (31), a driving crank (33) driven to rotate by the feeding and thread cutting driving source (20), a feeding connecting rod (34), and a feeding transmission assembly, the driving crank (33) extends a feeding arm (331) therefrom, the feeding arm (331) is rotationally connected with the feeding connecting rod (34), and the feeding transmission assembly is transmissionally connected between the feeding connecting rod (34) and a feeding connecting portion (311) of the rack (31). When the feeding arm (331) is collinear with the feeding connecting rod (34), the angle of the feeding arm (331) is φ0, and when the angle of the feeding arm (331) is within the range of φ0±β, the sewing machine has a small needle distance. The thread cutting mechanism (40) includes a movable knife (41), a thread cutting arm (332) extended from the driving crank (33), a thread cutting shaft (42) rotatable about its own axis, a thread cutting clutch assembly transmissionally connected between the thread cutting arm (332) and the thread cutting shaft (42), and a thread cutting transmission assembly transmissionally connected between the thread cutting shaft (42) and the movable knife (41). During the rotation of the driving crank (33) driven by the feeding and thread cutting driving source (20), the angle of the feeding arm (331) has feeding working zones and thread cutting working zones independent of each other, the thread cutting working zones are within the range of φ0±β, when the feeding arm (331) operates in the feeding working zones, the sewing machine has an effective needle distance, and the thread cutting clutch assembly is in a disengaged state; when the feeding arm (331) operates in the thread cutting working zones, the thread cutting clutch assembly is in an engaged state.

2. The feed and severing mechanism of claim 1, wherein: When the angle of the feeding arm (331) is within the range of φ0±β, the feeding and thread cutting driving source (20) drives the feeding teeth (32) to move in the front and back directions by an amount of not more than 1 mm.

3. The feed and severing mechanism of claim 1, wherein: The feeding and thread cutting driving source (20) is a driving motor (21), and the driving crank (33) is fixed on a motor shaft of the driving motor (21).

4. The feed and severing mechanism of claim 1, wherein: The effective length of the feeding arm (331) is less than that of the feeding connecting rod (34), the feeding transmission assembly includes a feeding shaft (35) rotatable about its own axis, a feeding crank (36) fixed on one end of the feeding shaft (35), and a rack seat (37) fixed on the other end of the feeding shaft (35), the feeding crank (36) is rotationally connected with the feeding connecting rod (34), and the rack seat (37) is connected with the feeding connecting portion (311) of the rack (31).

5. The feed and severing mechanism of claim 1, wherein: The effective length of the feeding arm (331) is greater than that of the feeding connecting rod (34); the feeding transmission assembly comprises a feeding shaft (35) rotatable about its axis, a tooth holder seat (37) fixed on the feeding shaft (35), and a feeding connecting arm (371) fixedly connected with the tooth holder seat (37), wherein the feeding connecting arm (371) is rotatably connected with the feeding connecting rod (34), and the tooth holder seat (37) is connected with the feeding connecting part (311) of the tooth holder (31).

6. The feed and severing mechanism of claim 1, wherein: The thread cutting clutch assembly comprises a thread cutting ball (43) rotatably mounted on the thread cutting arm (332), and a thread cutting driving member (44) fixed on the thread cutting shaft (42), wherein the thread cutting driving member (44) extends with a thread cutting driving arm (441) therefrom; When the feeding arm (331) operates in the feeding working area, the thread cutting ball (43) is separated from the thread cutting sliding groove surface on the thread cutting driving arm (441); When the feeding arm (331) operates in the thread cutting working area, the thread cutting ball (43) is in contact with the thread cutting sliding groove surface on the thread cutting driving arm (441).

7. The feed and severing mechanism of claim 1, wherein: The thread cutting mechanism (40) is a single-moving-knife structure, further comprises a fixed cutter (45), and the thread cutting transmission assembly comprises a thread cutting crank (46) fixed on the thread cutting shaft (42), a thread cutting connecting rod (47), and a rotatable moving-knife holder (48), wherein the two ends of the thread cutting connecting rod (47) are respectively hingedly connected with the thread cutting crank (46) and the moving-knife holder (48), and the moving knife (41) is fixed on the moving-knife holder (48).

8. The feed and severing mechanism of claim 6, wherein: The thread cutting mechanism (40) is a single-moving-knife structure, further comprises a fixed cutter (45), and the thread cutting transmission assembly comprises a thread cutting crank (46) fixed on the thread cutting shaft (42), a thread cutting connecting rod (47), and a rotatable moving-knife holder (48), wherein the two ends of the thread cutting connecting rod (47) are respectively hingedly connected with the thread cutting crank (46) and the moving-knife holder (48), and the moving knife (41) is fixed on the moving-knife holder (48).

9. A sewing machine characterized by: The sewing machine is provided with the feeding and thread cutting mechanism according to any one of claims 1-8.

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