Flat cutter thread trimming structure

Abstract

The utility model provides a flat cutter thread trimming structure, and belongs to the technical field of sewing machines. The flat cutter thread trimming device solves the problem that an existing flat cutter thread trimming device is poor in thread trimming stability due to fatigue of a spring. The flat cutter thread trimming structure is arranged on a bottom plate of the sewing machine and comprises a fixed cutter and a movable cutter capable of horizontally swinging, the flat cutter thread trimming structure further comprises a driving motor, an annular cylindrical cam, a transmission mechanism and a rod-shaped driving pin, an output shaft of the driving motor is horizontally arranged, and the cylindrical cam is fixedly arranged on the outer side of the output shaft in a sleeving mode. An annular guide groove is formed in the outer side of the cylindrical cam, one end of the driving pin extends into the guide groove, the transmission mechanism is connected between the driving pin and the movable cutter, and the driving pin can drive the movable cutter to swing towards the fixed cutter through the transmission mechanism when moving along the guide groove. The flat knife thread trimming structure has the advantage of being good in thread trimming stability.

Description

Technical Field

[0001] This utility model belongs to the field of sewing machine technology and relates to a flat blade thread cutting structure. Background Technology

[0002] Sewing machines are commonly used devices for sewing clothing. They use one or more sewing threads to create one or more stitches on the fabric, allowing one or more layers of fabric to interweave or sew together. After sewing is complete, the thread is cut by the thread-cutting device on the sewing machine head.

[0003] For example, a thread-cutting drive mechanism and a sewing machine for a sewing machine have been designed and a Chinese patent has been applied for, with application number 201610339727.1 and publication number CN105780326B. The thread-cutting drive mechanism includes: a drive shaft and a translational cam, a swing cam, and a lower thread-cutting cam mounted on the drive shaft and rotating with it; an upper scissor transmission assembly including a transmission block, a transmission rod, and a scissor holder connected in sequence, the scissor holder being connected to the top thread scissor assembly; the transmission rod passing through a rotating component; the transmission block contacting the translational cam; and the translational cam, when rotating, pushing the transmission block and transmission rod to move horizontally, causing the top thread scissor assembly to move forward or backward a certain distance; one side of the transmission block is provided with a pressure... The upper scissor transmission assembly includes a lever, a pressure lever, and a lower scissor drive assembly. The upper scissor drive assembly includes a first reset mechanism that resets the transmission lever after horizontal movement and a second reset mechanism that resets the scissor holder after vertical movement. The lower scissor drive assembly includes a drive block, a rotating shaft, a rocker arm, and a lower scissor connecting rod connected in sequence. The lower scissor connecting rod is connected to the lower scissor assembly. The drive block contacts the lower scissor cam. When the lower scissor cam rotates, it drives the rotating shaft to rotate via the drive block, which in turn drives the lower scissor assembly to complete the closing and opening cuts via the rocker arm and the lower scissor connecting rod. The lower scissor drive assembly also includes a third reset mechanism that resets the drive block.

[0004] However, in this wire-cutting drive mechanism, both the transmission block and the drive block are driven by the spring force against the outer circumferential surface of the cam that rotates with the drive shaft. The drive is then driven by the position change of the outer circumferential surface of the cam. Once the springs become fatigued due to long-term operation, it will directly affect the stable drive of the drive shaft for each wire-cutting action. Utility Model Content

[0005] The purpose of this invention is to address the aforementioned problems in the existing technology by proposing a flat blade wire cutting structure, which solves the problem of poor wire cutting stability caused by spring fatigue in existing flat blade wire cutting devices.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] A flat-blade thread-cutting structure is installed on the base plate of a sewing machine, including a fixed blade horizontally fixed on the base plate and a movable blade that can swing horizontally. The structure further includes a drive motor, an annular cylindrical cam, a transmission mechanism, and a rod-shaped drive pin. The output shaft of the drive motor is horizontally positioned. The cylindrical cam is sleeved and fixed to the outside of the output shaft. An annular guide groove is formed on the outside of the cylindrical cam. One end of the drive pin extends into the guide groove. When the drive motor drives the cylindrical cam to rotate circumferentially, the drive pin can move along the guide groove and reciprocate axially along the cylindrical cam. The transmission mechanism connects the drive pin and the movable blade, and when the drive pin moves along the guide groove, it can drive the movable blade to swing towards the fixed blade via the transmission mechanism.

[0008] When this flat-blade wire shearing structure needs to cut wire, the drive motor drives the cylindrical cam to rotate circumferentially, causing the drive pin to move along the guide groove. Guided by the guide groove, the drive pin can be displaced axially on the cylindrical cam. That is, the drive motor, through the cooperation of the guide groove of the cylindrical cam and the drive pin, can drive the drive pin to reciprocate axially on the cylindrical cam. At the same time, the movement of the drive pin also drives the moving blade to swing through the transmission mechanism, cooperating with the fixed blade to complete the wire cutting action. In this flat-blade wire shearing structure, the reciprocating drive of the horizontal swing of the moving blade is achieved by the cooperation of the annular guide groove and the drive pin, eliminating the need for an additional spring, avoiding spring fatigue, and ensuring the stability of the wire cutting operation.

[0009] In the aforementioned flat-blade wire shearing structure, the guide groove includes an arc-shaped displacement segment, and the end and middle of the displacement segment are spaced apart along the axial direction of the cylindrical cam. The space between the end and middle of the displacement segment along the axial direction of the cylindrical cam means that the bending deformation direction of the arc-shaped displacement segment is along the axial direction of the cylindrical cam. Therefore, when the drive pin extending into the guide groove moves along the displacement segment, it can undergo displacement relative to the axial direction of the cylindrical cam, thereby causing the rocker arm and drive rod to swing horizontally.

[0010] In the aforementioned flat-blade shearing structure, the number of displacement segments is at least two, and the extension directions of adjacent displacement segments are opposite. The arrangement of multiple displacement segments allows the drive rod and moving blade to perform multiple oscillating movements during one rotation of the cylindrical cam, improving transmission efficiency. The opposite extension directions of adjacent displacement segments refer to their opposite bending deformation directions. For example, if one displacement segment bends towards one end of the cylindrical cam, the other will bend towards the other end, ensuring that the middle positions of the two adjacent displacement segments are located on either side of the junction. This allows for a greater axial displacement of the drive pin on the same cylindrical cam.

[0011] In the above-mentioned flat blade wire cutting structure, the transmission mechanism includes a horizontally arranged swing arm, a drive rod, and a swingable movable handle. One end of the movable handle is linked to the moving blade. One end of the swing arm is rotatably mounted on the base plate. The other end of the swing arm is hinged to one end of the drive rod via the aforementioned drive pin. The other end of the drive rod is hinged to the other end of the movable handle.

[0012] In another scenario, in the aforementioned flat-blade wire shearing structure, the transmission mechanism includes a horizontally arranged plate-shaped fixed frame, a plate-shaped guide plate, a long strip-shaped transmission rod, and a swingable handle. One end of the swing handle is linked to the moving blade. The guide plate has a slotted hole, through which the other end of the drive pin passes and is hinged to one end of the transmission rod. The fixed frame has an arc-shaped hole, through which the other end of the transmission rod is hinged to the other end of the swing handle, with the hinge axis between them passing through the arc-shaped hole. The slotted hole in the guide plate limits and guides the movement of the drive pin, while the arc-shaped hole guides the movement of the other end of the transmission rod, ensuring transmission stability.

[0013] In the aforementioned flat-blade wire-cutting structure, the structure further includes a rod-shaped pivot screw. One end of the moving blade has a cutting edge that mates with the fixed blade. The other end of the moving blade is fitted around the pivot screw and can rotate circumferentially relative to it. The top of the moving blade has a protruding, columnar pin. One end of the movable handle has a recessed notch into which the pin passes. The pivot screw limits the position of the other end of the moving blade, ensuring the stability of its swing. Simultaneously, the engagement of the notch and the pin enables linkage between the non-coaxially rotating movable handle and the moving blade, resulting in a more stable and smoother wire-cutting action.

[0014] In the aforementioned flat-blade wire shearing structure, a clearance opening is vertically provided on the movable handle at a position corresponding to the shaft screw, and the upper end of the shaft screw extends into the clearance opening. The clearance opening shortens the vertical distance between the movable handle and the moving blade while preventing interference between them, thus improving the tightness of the linkage between the movable handle and the moving blade, and consequently enhancing the stability and accuracy of the wire shearing.

[0015] In the aforementioned flat-blade wire-cutting structure, the drive rod is bent into an arc shape towards the side away from the swing arm. The arc-shaped drive rod is better suited to its swinging movement, ensuring its service life and allowing space for the arrangement of other structures.

[0016] Compared with existing technologies, this flat blade wire cutting structure uses a drive motor as the driving component, and the reciprocating drive of the moving handle and the moving blade horizontally swings through the cooperation of an annular guide groove and a drive pin. It eliminates the need for additional springs, avoids spring fatigue, and ensures the stability of the wire cutting operation. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the flat blade shearing structure.

[0018] Figure 2 This is a schematic diagram of the structure from another perspective of Embodiment 1 of the flat blade shearing structure.

[0019] Figure 3 This is a schematic diagram of the cylindrical cam in the flat blade shearing structure.

[0020] Figure 4 This is a schematic diagram of the structure of Embodiment 2 of the flat blade shearing structure.

[0021] In the diagram, 1. Fixed frame; 2. Rotating shaft; 3. Fixed blade; 4. Moving blade; 41. Cutting edge; 42. Pin; 5. Movable handle; 51. Notch; 52. Clearance opening; 6. Drive motor; 7. Cylindrical cam; 71. Guide groove; 72. Displacement section; 8. Base shaft; 9. Rocker arm; 10. Drive rod; 11. Drive pin; 12. Shaft screw; 131. Arc hole; 14. Guide plate; 141. Strip hole; 15. Transmission rod. Detailed Implementation

[0022] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings. However, the present invention is not limited to these embodiments. Example 1

[0023] like Figure 1 and Figure 2 As shown, this flat blade wire cutting structure includes a fixed frame 1 for fixing on the base plate, a rotating shaft 2 that is vertically inserted through the fixed frame 1 and axially fixed to the fixed frame 1, a fixed blade 3 that is horizontally fixed on the fixed frame 1, a movable blade 4 that can be horizontally oscillatingly connected to the fixed frame 1, and a movable handle 5 that is sleeved on the outside of the rotating shaft 2 and can rotate around the axis of the rotating shaft 2.

[0024] In this embodiment, a cylindrical shaft screw 12 is vertically fixed on the fixed frame 1. One end of the movable blade 4 has a cutting edge 41 that mates with the fixed blade 3. The other end of the movable blade 4 is sleeved on the outside of the shaft screw 12 and can rotate circumferentially relative to the shaft screw 12. The top of the movable blade 4 has a protruding cylindrical pin 42. One end of the movable handle 5 has a recessed notch 51, and the pin 42 passes through the notch 51. In this embodiment, the diameter of the pin 42 is slightly smaller than the width of the notch 51. A clearance opening 52 is vertically provided on the movable handle 5 at the position corresponding to the shaft screw 12. The cross-section of the clearance opening 52 is arc-shaped, and the upper end of the shaft screw 12 extends into the clearance opening 52. The drive rod 10 is bent into an arc shape away from the swing rod 9.

[0025] The flat-blade thread-cutting structure also includes a drive motor 6, a circular cylindrical cam 7, a rod-shaped base shaft 8 vertically mounted on the sewing machine base plate, and a horizontally positioned swing arm 9 and drive rod 10. The output shaft of the drive motor 6 is horizontally positioned, and the cylindrical cam 7 is fitted and fixed to the outside of the output shaft. One end of the swing arm 9 is fitted to the outside of the base shaft 8, and the other end of the swing arm 9 is hinged to one end of the drive rod 10 via a rod-shaped drive pin 11. The other end of the drive rod 10 is hinged to the other end of the movable handle 5 via a rod-shaped hinge shaft. A circular guide groove 71 is provided on the outer side of the cylindrical cam 7. One end of the drive pin 11 extends into the guide groove 71, and when the drive pin 11 moves along the guide groove 71, it can drive the swing arm 9 to rotate around the axis of the base shaft 8. In this embodiment, the drive pin 11 includes a connecting shaft and a guide shaft arranged coaxially. The rocker arm 9 and the drive rod 10 are both sleeved on the outside of the connecting shaft to form a hinge. The guide shaft is located on the rocker arm 9 and is integrated with the rocker arm 9. The end of the guide shaft extends into the guide groove 71 to form a guiding engagement with the guide groove 71.

[0026] like Figure 3 As shown, the guide groove 71 includes an arc-shaped segment and an arc-shaped displacement segment 72 arranged around the axis of the cylindrical cam 7. The ends and middle portions of the displacement segment 72 are spaced apart along the axial direction of the cylindrical cam 7. Here, there are two displacement segments 72, and the extension directions of adjacent displacement segments 72 are opposite, that is, adjacent displacement segments 72 are connected to form a shape similar to a sine wave, and this sine wave is arranged with the circumferential direction of the cylindrical cam 7 as the X-axis and the axial direction of the cylindrical cam 7 as the Y-axis. In this embodiment, the groove depth of the guide groove 71 is consistent throughout.

[0027] When this flat-blade wire-cutting structure needs to cut wire, the drive motor 6 drives the cylindrical cam 7 to rotate circumferentially, causing the drive pin 11 to move along the guide groove 71 and drive the swing arm 9 to rotate horizontally around the axis of the base shaft 8. At the same time, the movement of the drive pin 11 also causes the drive rod 10 to swing horizontally, thereby causing the movable handle 5 to rotate circumferentially around the rotating shaft 2. Through the cooperation of the notch 51 and the pin 42, the moving blade 4 is driven to swing around the shaft screw 12, and cooperates with the fixed blade 3 to complete the wire-cutting action. Example 2

[0028] like Figure 4As shown, the technical solution of this embodiment is largely the same as that of Embodiment 1, except that: the transmission mechanism includes a plate-shaped fixed frame 1, a plate-shaped guide plate 14, a long strip-shaped transmission rod 15, and a swingable movable handle 5, all of which are horizontally arranged. One end of the movable handle 5 is linked with the moving knife 4. A straight strip-shaped hole 141 is provided on the guide plate 14. The other end of the drive pin 11 passes through the strip-shaped hole 141 and is hinged to one end of the transmission rod 15. An arc hole 131 is provided on the fixed frame 1. The other end of the transmission rod 15 is hinged to the other end of the movable handle 5, and the hinge shaft between the two passes through the arc hole 131.

[0029] The specific embodiments described herein are merely illustrative examples illustrating the spirit of this utility model. Those skilled in the art to which this utility model pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of this utility model or exceeding the scope defined by the appended claims.

Claims

1. A flat-blade thread-cutting structure, disposed on the base plate of a sewing machine, comprising a fixed blade (3) horizontally fixed on the base plate and a movable blade (4) capable of horizontal swinging, characterized in that, The flat-blade wire shearing structure also includes a drive motor (6), an annular cylindrical cam (7), a transmission mechanism, and a rod-shaped drive pin (11). The output shaft of the drive motor (6) is horizontally arranged. The cylindrical cam (7) is sleeved and fixed on the outside of the output shaft. An annular guide groove (71) is provided on the outside of the cylindrical cam (7). One end of the drive pin (11) extends into the guide groove (71). When the drive motor (6) drives the cylindrical cam (7) to rotate circumferentially, the drive pin (11) can move along the guide groove (71) and reciprocate along the axial direction of the cylindrical cam (7). The transmission mechanism... Connected between the drive pin (11) and the moving blade (4), and when the drive pin (11) moves along the guide groove (71), it can drive the moving blade (4) to swing towards the fixed blade (3) through the transmission mechanism. The transmission mechanism includes a horizontally arranged swing rod (9), a drive rod (10), and a swingable movable handle (5). One end of the movable handle (5) is linked to the moving blade (4). One end of the swing rod (9) is rotatably mounted on the base plate. The other end of the swing rod (9) is hinged to one end of the drive rod (10) through the drive pin (11). The other end of the drive rod (10) is hinged to the other end of the movable handle (5).

2. The flat blade wire cutting structure according to claim 1, characterized in that, The guide groove (71) includes an arc-shaped displacement segment (72), and the end of the displacement segment (72) and the middle of the displacement segment (72) are spaced apart in the axial direction of the cylindrical cam (7).

3. The flat blade wire cutting structure according to claim 1, characterized in that, The flat blade shearing structure also includes a rod-shaped axial screw (12). One end of the moving blade (4) has a cutting edge (41) that cooperates with the fixed blade (3). The other end of the moving blade (4) is sleeved on the outside of the axial screw (12) and can rotate circumferentially relative to the axial screw (12). The top of the moving blade (4) has a protruding columnar pin (42). One end of the movable handle (5) has a recessed notch (51), and the pin (42) passes through the notch (51).

4. The flat blade wire cutting structure according to claim 3, characterized in that, A clearance opening (52) is provided vertically through the movable handle (5) at the position corresponding to the shaft screw (12), and the upper end of the shaft screw (12) extends into the clearance opening (52).

5. The flat blade wire cutting structure according to claim 1, characterized in that, The drive rod (10) bends into an arc shape away from the swing rod (9).

6. A flat-blade thread-cutting structure, disposed on the base plate of a sewing machine, comprising a fixed blade (3) horizontally fixed on the base plate and a movable blade (4) capable of horizontally swinging, characterized in that, The flat blade shearing structure also includes a drive motor (6), an annular cylindrical cam (7), a transmission mechanism, and a rod-shaped drive pin (11). The output shaft of the drive motor (6) is horizontally arranged. The cylindrical cam (7) is sleeved and fixed on the outside of the output shaft. An annular guide groove (71) is provided on the outside of the cylindrical cam (7). One end of the drive pin (11) extends into the guide groove (71). When the drive motor (6) drives the cylindrical cam (7) to rotate circumferentially, the drive pin (11) can move along the guide groove (71) and reciprocate along the axial direction of the cylindrical cam (7). The transmission mechanism is connected between the drive pin (11) and the moving blade (4), and the drive pin (11) moves along the guide groove (71). When the slot (71) moves, it can drive the moving blade (4) to swing toward the fixed blade (3) through the transmission mechanism. The transmission mechanism includes a plate-shaped fixed frame (1), a plate-shaped guide plate (14), a long strip-shaped transmission rod (15), and a swingable handle (5) that are all horizontally arranged. One end of the handle (5) is linked to the moving blade (4). The guide plate (14) has a strip-shaped hole (141). The other end of the drive pin (11) passes through the strip-shaped hole (141) and is hinged to one end of the transmission rod (15). The fixed frame (1) has an arc-shaped hole (131). The other end of the transmission rod (15) is hinged to the other end of the handle (5), and the hinge shaft between the two passes through the arc-shaped hole (131).

7. A flat-blade wire-cutting structure according to claim 6, characterized in that, The flat blade shearing structure also includes a rod-shaped axial screw (12). One end of the moving blade (4) has a cutting edge (41) that cooperates with the fixed blade (3). The other end of the moving blade (4) is sleeved on the outside of the axial screw (12) and can rotate circumferentially relative to the axial screw (12). The top of the moving blade (4) has a protruding columnar pin (42). One end of the movable handle (5) has a recessed notch (51), and the pin (42) passes through the notch (51).

8. The flat blade wire cutting structure according to claim 7, characterized in that, A clearance opening (52) is provided vertically through the movable handle (5) at the position corresponding to the shaft screw (12), and the upper end of the shaft screw (12) extends into the clearance opening (52).

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