CN220907859U - Sewing machine cuts line device and sewing machine - Google Patents

Abstract

The utility model provides a sewing machine thread cutting device and a sewing machine, wherein the sewing machine thread cutting device comprises a fixed cutter and a movable cutter which is fixedly arranged and can move towards a direction close to or far away from the fixed cutter, needle dropping points which are distributed right below a needle in the sewing machine and are positioned in a certain position are arranged on the periphery of the movable cutter, a seam lifting hook groove, a seam lifting cutting edge and a seam post-cutting edge are arranged on the movable cutter, the seam lifting hook groove penetrates the movable cutter along the thickness direction of the movable cutter and allows the needle to pass through, the seam lifting cutting edge and the seam post-cutting edge can be engaged with the fixed cutter, and the seam lifting cutting edge is arranged close to the seam post-cutting edge; when the seam lifting cutting edge is meshed with the fixed knife, the seam lifting cutting edge is adjacent to the needle dropping point, so that the seam lifting cutting edge is adjacent to the needle dropping point. The utility model ensures that the edge of the seam lifting and cutting line is close to the needle falling point when the seam lifting and cutting line is lifted, so that the seam lifting head remained on the seam material after the seam lifting and cutting line is lifted is shorter, the generation of seam lifting bird nest thread head can be reliably avoided, and the subsequent secondary trimming of longer seam lifting head can be avoided.

Description

Sewing machine thread trimming device and sewing machine

Technical Field

The utility model relates to the technical field of automatic thread trimming of sewing machines, in particular to a thread trimming device for sewing machines and a sewing machine comprising the thread trimming device.

Background technique

At present, sewing machines are equipped with thread trimmers. When sewing is finished, the thread trimmers are activated to cut the upper and lower threads. After thread trimming, there are thread ends (including upper and lower thread ends) left on the sewing material, and at the same time, a section of the upper thread ends will be left on one side of the needle. The next time you start sewing, the upper thread ends on the needle side will form a bird's nest-shaped seam starter on the sewing material. In order to ensure the appearance quality of the sewing material, workers must cut off the bird's nest-shaped seam starter, which increases the labor intensity and also affects the production efficiency of the sewing material.

In the prior art, some sewing machines are also equipped with a seam start thread trimming device, which is used to cut off the upper thread end when sewing to avoid the formation of seam start thread ends. However, after the upper thread end is cut off, the seam start thread end remaining on the sewing material still has a certain length, and it is still inevitable that workers need to trim the seam start thread end.

Utility Model Content

In view of the above-mentioned shortcomings of the prior art, the technical problem to be solved by the utility model is to provide a thread trimming device for a sewing machine, which can avoid the generation of bird's nest thread ends at the start of the seam and can also make the thread ends at the start of the seam on the sewing material shorter.

To achieve the above-mentioned purpose, the utility model provides a thread trimming device for a sewing machine, comprising a fixed fixed knife and a movable knife capable of moving toward or away from the fixed knife, wherein the outer periphery of the movable knife has a needle drop point which is distributed directly below a machine needle in the sewing machine and has a fixed position, wherein the movable knife is provided with a thread-starting groove, a thread-starting cutting edge, and a thread-post-sewing cutting edge, wherein the thread-starting groove penetrates the movable knife along the thickness direction of the movable knife and allows the machine needle to pass through, wherein the thread-starting cutting edge and the thread-post-sewing cutting edge can both engage with the fixed knife, and the thread-starting cutting edge is arranged adjacent to the thread-post-sewing cutting edge;

When the seam-starting thread-cutting edge is engaged with the fixed knife, the seam-post-cutting thread-cutting edge is adjacent to the needle drop point, so that the seam-starting thread-cutting edge is adjacent to the needle drop point.

Furthermore, the movable knife is a circular arc knife body;

Along the circumferential direction of the movable knife, the circumferential distance between the thread cutting edge at the beginning of the seam and the thread cutting edge after the seam is 0-6 mm;

Along the axial direction of the movable knife, the axial distance between the thread cutting edge at the beginning of seaming and the thread cutting edge after seaming is 0-4 mm.

Furthermore, when the thread trimming edge at the beginning of sewing is engaged with the fixed knife, the distance between the thread trimming edge after sewing and the needle drop point is 1-6 mm.

Furthermore, a wire dividing groove is provided on the movable knife;

When the seam starting and thread cutting edge is engaged with the fixed knife, the needle drop points are distributed in the line dividing groove.

Furthermore, a first wire accommodating groove is provided on the surface of the movable knife facing the fixed knife, and two ends of the first wire accommodating groove extend to the post-sewing wire cutting edge and the wire dividing groove respectively.

Furthermore, a first cutting edge forming portion and a second cutting edge forming portion are provided on the surface of the movable knife facing the fixed knife, the cutting edge for starting seaming is formed at the edge of the first cutting edge forming portion, and the cutting edge for cutting after seaming is formed at the edge of the second cutting edge forming portion;

The first cutting edge forming portion and the second cutting edge forming portion are staggered, and the seam-starting thread-cutting cutting edge is distributed on the side of the seam-post-cutting thread-cutting cutting edge facing the wire dividing groove.

Furthermore, a first cutting edge forming portion and a second cutting edge forming portion are provided on the surface of the movable knife facing the fixed knife, the cutting edge for starting seaming is formed at the edge of the first cutting edge forming portion, and the cutting edge for cutting after seaming is formed at the edge of the second cutting edge forming portion;

The first cutting edge forming portion and the second cutting edge forming portion are the same cutting edge forming portion, the seam starting cutting edge is distributed on the side of the seam after cutting edge facing away from the dividing groove, and the seam starting cutting edge and the seam after cutting edge are distributed on the same circumference line of the movable knife.

Furthermore, a second thread accommodating groove is provided on the surface of the movable knife facing the fixed knife, and two ends of the second thread accommodating groove extend to the seam starting thread hooking groove and the seam starting thread cutting edge respectively.

Furthermore, the fixed knife includes a start-sewing thread trimming fixed knife and a post-sewing thread trimming fixed knife. The start-sewing thread trimming fixed knife is distributed on one side of the machine needle and can engage with the start-sewing thread trimming cutting edge. The post-sewing thread trimming fixed knife is distributed on the other side of the machine needle and can engage with the post-sewing thread trimming cutting edge.

Furthermore, the thread trimming device of the sewing machine further comprises a fixedly arranged thread pressing plate, wherein the thread pressing plate, the thread trimming fixed knife and the movable knife are arranged in sequence from the outside to the inside along the radial direction of the rotary hook in the sewing machine; the movable knife is provided with a first thread pressing portion, and the thread pressing plate is provided with a second thread pressing portion distributed on the outer end side of the thread trimming fixed knife;

When the seam start thread trimming cutting edge is close to the seam start thread trimming fixed knife and is not engaged, the first thread pressing portion abuts against the second thread pressing portion to form a thread clamping seam for clamping the surface thread.

Furthermore, the movable knife is provided with a first thread pressing portion, and the seam starting and thread cutting fixed knife is provided with a third thread pressing portion;

When the seam start thread trimming cutting edge is close to the seam start thread trimming fixed knife and is not engaged, the first thread pressing portion abuts against the third thread pressing portion to form a thread clamping seam for clamping the upper thread.

Furthermore, the thread trimming device of the sewing machine also includes a fixedly arranged suction pipe, which has a suction port aligned with the seam start thread hook groove, and the seam start thread trimming fixed knife, the suction port and the movable knife are arranged in sequence from the outside to the inside along the radial direction of the rotary shuttle in the sewing machine.

The utility model also provides a sewing machine, in which the sewing machine thread trimming device as described above is installed.

As described above, the sewing machine thread trimming device and the sewing machine involved in the utility model have the following beneficial effects:

In the present application, the seam start cutting edge is set to be close to the post-sewing cutting edge that is adjacent to the needle drop point when the seam start cutting is performed, so that the seam start cutting edge is close to the needle drop point when the seam start cutting is performed, that is, very close to the machine needle, so that the seam start thread end remaining on the sewing material after the seam start cutting is shorter, which can reliably avoid the formation of seam start bird's nest thread ends, and can also avoid the subsequent secondary trimming of the longer seam start thread ends, which can not only reduce the manual labor intensity, but also greatly improve the production efficiency and sewing material quality.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a side view of the thread trimming device of a sewing machine according to the present invention.

FIG. 2 a is a schematic structural diagram of a first embodiment of a movable knife in the present utility model.

FIG. 2b is a top view of FIG. 2a .

FIG. 2c is a top view of the second embodiment of the movable knife in the present invention.

FIG. 2d is a top view of the third embodiment of the movable knife in the present utility model.

FIG. 2e is a top view of the fourth embodiment of the movable knife in the utility model.

FIG. 2f is a top view of the fifth embodiment of the movable knife in the utility model.

FIG. 2g is a top view of the sixth embodiment of the movable knife in the present utility model.

(The movable knife in Figures 2b to 2g is in the position where the seam-starting cutting edge is engaged with the fixed knife.)

FIG3 is a schematic structural diagram of a medium voltage line board of the present invention.

FIG. 4 is a schematic diagram of the state of the thread trimming device of the sewing machine of the utility model when sewing the first stitch.

Fig. 5 is a schematic diagram of the state of the thread trimming device of the sewing machine of the utility model when starting to sew the second stitch.

Fig. 6 is a schematic diagram of the state of the thread trimming device of the sewing machine of the utility model when trimming the thread needle after sewing.

Component number description

10 Fixed knife

101 Seam trimming fixed knife

102 Fixed knife for thread trimming after sewing

20 Cutting

21 Seam hook groove

22 Seam cutting edge

23 Cutting edge for thread trimming after sewing

24 wiring slots

25 First cable tray

26 Second cable tray

27 First cutting edge forming portion

28 Second cutting edge forming portion

30 Needle Drop Point

40 Pressing plate

41 Second crimping section

50 Suction pipe

51 Air intake

60 Needle

70 Hook

Detailed ways

The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

It should be noted that the structures, proportions, sizes, etc. drawn in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the utility model, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by the utility model, should still fall within the scope of the technical content disclosed by the utility model. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and so on quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the utility model. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the utility model without substantial change of the technical content.

It should also be noted that when an element is referred to as being "fixed on" or "disposed on" another element, it may be directly on the other element or there may be an intermediate element at the same time. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or may be indirectly connected to the other element through an intermediate element.

In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

The utility model provides a sewing machine, and in particular provides a sewing thread trimming device for the sewing machine. Usually, the sewing machine is provided with a needle 60 that can reciprocate up and down, and a rotatable shuttle 70. In the following embodiments, the axial direction of the shuttle 70 is defined as the left-right direction, the extension direction of the needle 60 is defined as the up-down direction, and the direction orthogonal to both the left-right direction and the up-down direction is defined as the front-back direction. Based on this, in the view shown in FIG1 , the upper side and the lower side of the paper are the upper direction and the lower direction, respectively, the left side and the right side of the paper are the front direction and the rear direction, respectively, and the front and the back of the paper are the left direction and the right direction, respectively.

As shown in Fig. 1, the thread trimming device of a sewing machine involved in the utility model comprises a fixed fixed knife 10 and a movable knife 20, and the movable knife 20 can move in a direction close to or away from the fixed knife 10. As shown in Fig. 2a and Fig. 2b, the outer periphery of the movable knife 20 has a needle drop point 30 distributed directly below the needle 60 in the sewing machine, that is, the needle drop point 30 is a point on the extension surface of the movable knife 20 when the needle 60 moves up and down, so the position of the needle drop point 30 distributed on the outer periphery of the movable knife 20 is determined. At the same time, the movable knife 20 is provided with a seam start thread hook groove 21, a seam start thread cutting edge 22, and a post-sewing thread cutting edge 23. The seam start thread hook groove 21 penetrates the movable knife 20 along the thickness direction of the movable knife 20 and allows the machine needle 60 to pass through. The seam start thread hook groove 21 is aligned with the needle drop point 30 in the left and right directions; the seam start thread cutting edge 22 and the post-sewing thread cutting edge 23 can both engage with the fixed knife 10, and the seam start thread hook groove 21 is distributed on the front side of the seam start thread cutting edge 22. With the after-sewing thread trimming edge 23 as a reference, the starting seam thread trimming edge 22 is arranged adjacent to the after-sewing thread trimming edge 23; when the starting seam thread trimming edge 22 is engaged with the fixed knife 10, the after-sewing thread trimming edge 23 is adjacent to the needle drop point 30, and the starting seam thread trimming edge 22 is arranged close to the after-sewing thread trimming edge 23, so that when the starting seam thread trimming edge 22 is engaged with the fixed knife 10, the starting seam thread trimming edge 22 is adjacent to the needle drop point 30.

The thread trimming device for a sewing machine can be used for thread trimming at the beginning of sewing and can also be used for thread trimming at the end of sewing.

During normal sewing, the movable knife 20 is in an initial position away from the fixed knife 10 .

When the thread needs to be trimmed after sewing, during the process of the sewing machine sewing the last stitch, after the needle 60 moves upward over the movable knife 20, the movable knife 20 moves toward the direction close to the fixed knife 10, as shown in Figure 6. During this process, the movable knife 20 will move with the suture thread toward the fixed knife 10 until the post-sewing thread trimming edge 23 engages with the fixed knife 10 and cuts the suture thread. After the suture thread is cut, a section of the needle thread remains on one side of the needle 60. After the thread trimming is completed, the movable knife 20 returns to its initial position.

When starting to sew next time, before the sewing machine starts to sew the first stitch, the movable knife 20 moves so that the thread hook groove 21 moves to the right below the needle 60; or, when the sewing machine needle 60 moves down, the movable knife 20 moves at the same time so that the thread hook groove 21 moves to the right below the needle 60. After that, the sewing machine needle 60 moves down for the first stitch, and the needle 60 passes the upper thread downward through the thread hook groove 21 with the upper thread, as shown in FIG4 , and under the action of the rotary shuttle 70, the thread end of the upper thread on one side of the needle 60 is driven to the bottom of the movable knife 20. After that, the sewing machine needle 60 moves up for the first stitch, and after the needle 60 moves upward away from the movable knife 20, the movable knife 20 moves in the direction close to the fixed knife 10, as shown in FIG5 , and the thread end of the upper thread is pulled out upward; when the thread cutting edge 22 of the sewing machine is engaged with the fixed knife 10, the thread end of the upper thread is cut off, thereby avoiding the formation of the thread end of the sewing machine needle 60. In particular, when the seam start thread cutting edge 22 engages with the fixed knife 10 to cut off the start thread end, the seam start thread cutting edge 22 is close to the needle drop point 30, that is, the seam start thread cutting edge 22 is very close to the needle 60 at this time, so the start thread end remaining on the sewing material after cutting off the start thread end is very short.

Therefore, the present invention can simultaneously realize the seam start trimming and the post-sewing trimming, and in particular, reliably realize that the seam start thread head remaining on the sewing material after the seam start trimming is shorter, which can reliably avoid the generation of seam start thread heads and avoid the subsequent secondary trimming of the longer seam start thread heads, which can reduce the manual labor intensity and greatly improve the production efficiency and the quality of the sewing materials.

Furthermore, the thread trimming device of the sewing machine further includes a thread trimming drive source and a thread trimming transmission mechanism. The thread trimming drive source is usually a motor. The thread trimming drive source is connected to the movable knife 20 through the thread trimming transmission mechanism to drive the movable knife 20 to move toward or away from the fixed knife 10. In this embodiment, the movable knife 20 moves in a rotational manner. Based on this, as shown in FIG. 1 and FIG. 2a, the movable knife 20 is preferably a circular arc knife body.

Further, as shown in Fig. 2a to Fig. 2f, a dividing groove 24 is provided on the movable knife 20, and the dividing groove 24 is used for dividing the thread when trimming the thread after sewing. When the starting and trimming edge 22 is engaged with the fixed knife 10, the needle drop point 30 is distributed in the dividing groove 24, preferably, the needle drop point 30 is distributed on the front end side of the dividing groove 24 near the trimming edge 23 after sewing.

Furthermore, the seam start thread cutting edge 22 is arranged at a position close to the periphery of the post-sewing thread cutting edge 23, preferably satisfying the following conditions: as shown in Fig. 2a and Fig. 2b, along the circumferential direction of the movable knife 20, i.e., along the rotation direction of the movable knife 20, the circumferential distance Y between the seam start thread cutting edge 22 and the post-sewing thread cutting edge 23 is 0-6 mm; along the axial direction of the movable knife 20, i.e., along the left-right direction, the axial distance Z between the seam start thread cutting edge 22 and the post-sewing thread cutting edge 23 is 0-4 mm, so that the seam start thread cutting edge 22 is arranged close to the post-sewing thread cutting edge 23. In addition, by setting the circumferential distance Y and axial distance Z between the seam start thread cutting edge 22 and the post-sewing thread cutting edge 23, the distance W between the post-sewing thread cutting edge 23 and the needle drop point 30 when the seam start thread cutting edge 22 and the fixed knife 10 are engaged is 1-6 mm, thereby better achieving the seam start thread cutting effect of shorter residual thread ends on the sewing material when starting the seam.

Further, as shown in FIG1 , the movable knife 20 is arranged below the fixed knife 10, and the movable knife 20 can rotate below the fixed knife 10. The formation structure of the thread cutting edge 22 at the beginning of the seam and the thread cutting edge 23 after the seam is as follows: as shown in FIG2a and FIG2b , the surface of the movable knife 20 facing the fixed knife 10 is provided with a first edge forming portion 27 and a second edge forming portion 28, the thread cutting edge 22 at the beginning of the seam is formed at the front edge of the first edge forming portion 27, and the thread cutting edge 23 after the seam is formed at the rear edge of the second edge forming portion 28. There can be multiple positional relationships between the thread cutting edge 22 at the beginning of the seam, the thread cutting edge 23 after the seam, and the dividing groove 24, as long as the distance between the thread cutting edge 23 after the seam and the needle drop point 30 can be within a set range when the thread cutting edge 22 at the beginning of the seam is engaged with the fixed knife 10. Based on this, the movable knife 20 has the following preferred embodiments.

Embodiment 1 of the movable knife 20, as shown in FIG2a and FIG2b, the thread cutting edge 23 after sewing and the dividing groove 24 are distributed on the same circumference of the movable knife 20, and the dividing groove 24 is distributed on the rear side of the thread cutting edge 23 after sewing. The first edge forming portion 27 and the second edge forming portion 28 are two edge forming portions, and are staggered. The first edge forming portion 27 is distributed on the right rear side of the second edge forming portion 28, so that the thread cutting edge 22 for starting sewing is distributed on the rear side of the thread cutting edge 23 after sewing toward the dividing groove 24. In addition, the first edge forming portion 27 and the second edge forming portion 28 can be a bulge structure protruding upward from the movable knife 20, or a plane structure flush with the upper surface of the movable knife 20.

The second embodiment of the movable knife 20 is shown in FIG. 2 c , and is different from the first embodiment of the movable knife 20 in that when the thread cutting edge 22 at the beginning of sewing is engaged with the fixed knife 10 , the thread cutting edge 23 after sewing is brought closer to the needle drop point 30 .

The third embodiment of the movable knife 20, as shown in Figure 2d, differs from the second embodiment of the movable knife 20 in that: the first cutting edge forming portion 27 and the second cutting edge forming portion 28 are the same cutting edge forming portion, and the seam start thread cutting edge 22 is distributed on the front side of the seam after thread cutting edge 23 facing away from the dividing groove 24; and, the seam start thread cutting edge 22 and the seam after thread cutting edge 23 are distributed on the same circumference line of the movable knife 20, that is, the seam start thread cutting edge 22, the seam after thread cutting edge 23 and the dividing groove 24 are distributed in sequence from front to back.

The fourth embodiment of the movable knife 20, as shown in FIG. 2e, is different from the third embodiment of the movable knife 20 in that the first edge forming portion 27 and the second edge forming portion 28 are two edge forming portions, and are staggered, and the first edge forming portion 27 is distributed on the left front side of the second edge forming portion 28, so that the seam start thread cutting edge 22 is distributed on the front side of the seam back thread cutting edge 23 facing away from the dividing groove 24. And the first edge forming portion 27 and the second edge forming portion 28 are arranged closely, so the seam start thread cutting edge 22 and the seam back thread cutting edge 23 are also arranged closely.

The fifth embodiment of the movable knife 20, as shown in FIG. 2f, is different from the first embodiment of the movable knife 20 in that the thread cutting edge 23 after sewing and the line dividing groove 24 are staggered and distributed left and right, and the line dividing groove 24 is distributed on the left rear side of the thread cutting edge 23 after sewing. The first edge forming portion 27 and the second edge forming portion 28 are two edge forming portions, and are staggered and distributed. The first edge forming portion 27 is distributed on the left rear side of the second edge forming portion 28, so that the thread cutting edge 22 for starting sewing is distributed on the rear side of the thread cutting edge 23 after sewing toward the line dividing groove 24.

Furthermore, in the first to fifth embodiments of the movable knife 20, as shown in Fig. 2a to Fig. 2f, the upper surface of the movable knife 20 facing the fixed knife 10 is provided with a first thread accommodating groove 25, and the two ends of the first thread accommodating groove 25 extend to the thread cutting edge 23 after sewing and the thread dividing groove 24 respectively. The upper surface of the movable knife 20 facing the fixed knife 10 is provided with a second thread accommodating groove 26, and the two ends of the second thread accommodating groove 26 extend to the thread hooking groove 21 for starting sewing and the thread cutting edge 22 for starting sewing respectively. The first thread accommodating groove 25 and the second thread accommodating groove 26 are both grooves on the upper surface of the movable knife 20, and neither of them penetrates downwardly through the bottom of the movable knife 20. When the movable knife 20 rotates with the upper thread and the lower thread toward the fixed knife 10 during thread cutting after sewing, the upper thread and the lower thread are accommodated in the first thread accommodating groove 25. When the movable knife 20 rotates with the needle thread end toward the fixed knife 10, the needle thread end is accommodated in the second thread receiving groove 26, which can prevent the needle thread end from being entangled in the rotary hook 70 again. Preferably, along the circumference of the movable knife 20, that is, along the rotation direction of the movable knife 20, the length X of the first thread receiving groove 25 is 0-5mm.

Preferably, as shown in FIG. 2g, the seam start thread hooking groove 21 can be arranged adjacent to the seam start thread cutting edge 22, then the second thread containing groove 26 can be cancelled, and only the seam start thread hooking groove 21 is arranged, and the rear end of the seam start thread hooking groove 21 extends to the seam thread cutting edge 22. At the same time, the first edge forming portion 27 and the second edge forming portion 28 are the same edge forming portion, the seam start thread cutting edge 22 is distributed on the front side of the back seam thread cutting edge 23 facing away from the line dividing groove 24, and the seam start thread hooking groove 21, the seam start thread cutting edge 22, the back seam thread cutting edge 23 and the needle drop point 30 are distributed on the same circumference line of the movable knife 20.

Furthermore, as shown in Figure 1, the fixed knife 10 includes a fixed knife 101 for cutting the thread at the start of sewing and a fixed knife 102 for cutting the thread after sewing; the fixed knife 101 for cutting the thread at the start of sewing is distributed on the front side of the machine needle 60, and can engage with the cutting edge 22 for cutting the thread at the start of sewing, and is used for cutting the thread at the start of sewing; the fixed knife 102 for cutting the thread after sewing is distributed on the rear side of the machine needle 60, and can engage with the cutting edge 23 for cutting the thread after sewing, and is used for cutting the thread after sewing.

Furthermore, when starting to cut the thread, when the movable knife 20 rotates with the needle thread end toward the direction close to the starting to cut the thread fixed knife 101 until the starting to cut the thread edge 22 is close to the starting to cut the thread fixed knife 101, but the two are not engaged, the needle thread end will be clamped; at this time, the sewing machine will sew the second stitch, the third stitch... in this state to prevent the needle thread end from being disengaged; after the sewing machine sets the number of stitches for sewing, the movable knife 20 continues to rotate with the needle thread end toward the direction close to the starting to cut the thread fixed knife 101 until the starting to cut the thread edge 22 is engaged with the starting to cut the thread fixed knife 101, and the needle thread is cut. Based on this, there are two ways to achieve the clamping of the needle thread end.

Mode 1, as shown in FIG. 1 and FIG. 3, the thread trimming device of the sewing machine further includes a fixedly arranged thread pressing plate 40, the thread pressing plate 40, the thread trimming fixed knife 101 and the movable knife 20 are arranged in sequence from the outside to the inside along the radial direction of the rotary hook 70 in the sewing machine; the movable knife 20 is provided with a first thread pressing portion, and the thread pressing plate 40 is provided with a second thread pressing portion 41 distributed on the outer end side of the thread trimming fixed knife 101, that is, the second thread pressing portion 41 is arranged at the rear end of the thread pressing plate 40 and distributed on the rear end side of the thread trimming fixed knife 101. When the thread trimming cutting edge 22 is adjacent to the thread trimming fixed knife 101 and is not engaged, the first thread pressing portion abuts against the second thread pressing portion 41 and forms a thread clamping seam for clamping the upper thread, and the upper thread end of the needle start thread is clamped by the mutual cooperation of the movable knife 20 and the thread pressing plate 40.

Method 1: No thread pressing plate 40 is provided; specifically, a first thread pressing portion is provided on the movable knife 20, and a third thread pressing portion is provided on the fixed knife 101 for starting seam cutting. When the thread pressing edge 22 for starting seam cutting is close to the fixed knife 101 for starting seam cutting and not engaged, the first thread pressing portion abuts against the third thread pressing portion and forms a thread clamping seam for clamping the surface thread. The movable knife 20 and the fixed knife 101 for starting seam cutting cooperate with each other to clamp the thread end of the starting needle thread.

Furthermore, as shown in FIG1 , the thread trimming device of the sewing machine further includes a fixedly arranged suction pipe 50, the suction pipe 50 has a suction port 51 aligned with the thread hooking groove 21, and the suction pipe 50 is also aligned with the second thread receiving groove 26, and the thread trimming fixed knife 101, the suction port 51 and the movable knife 20 are arranged in sequence from the outside to the inside along the radial direction of the rotary hook 70 in the sewing machine. In the process of preventing bird nests in the thread trimming and starting, a negative pressure thread suction action is generated at the suction port 51 of the suction pipe 50, so that the thread ends of the needle thread in the second thread receiving groove 26 are just in the negative pressure area of the suction port 51, so that the thread ends of the needle thread are picked up; and after the thread trimming and starting, the cut needle thread ends are sucked away by the negative pressure of the suction port 51, so that the thread ends of the surface thread are collected.

Preferably, the starting thread trimming fixed knife 101, the post-sewing thread trimming fixed knife 102, the thread pressing plate 40 and the air suction pipe 50 are all fixed to the bottom plate of the sewing machine. In addition, when a different movable knife 20 is used, that is, when the relative positions of the starting thread trimming edge 22 and the post-sewing thread trimming edge 23 on the movable knife 20 change, the position of the starting thread trimming fixed knife 101 matched with the starting thread trimming edge 22 and the position of the thread pressing plate 40 will change relatively, and the position of the post-sewing thread trimming fixed knife 102 matched with the post-sewing thread trimming edge 23 will also change relatively.

In summary, the working principle of the sewing machine thread trimming device involved in the present application is as follows, and the configuration of the thread pressing plate 40 is taken as an example. In addition, when the movable knife 20 is in the initial position, the movable knife 20 is distributed below the fixed knife 101 for starting and trimming the thread, that is, distributed in front of the needle 60.

1. The thread trimming device of a sewing machine is used for sewing and thread trimming to prevent bird nests, and includes the following steps:

1.1. When sewing starts next time, before the sewing machine starts sewing the first stitch, the movable knife 20 rotates backwards, and the angle of view in FIG1 is clockwise, so that the thread hooking groove 21 rotates backwards to the right below the needle 60; or, when the sewing machine needle 60 moves down for the first stitch, the movable knife 20 rotates backwards at the same time, so that the thread hooking groove 21 rotates backwards to the right below the needle 60. At the same time, the air suction port 51 of the air suction pipe 50 generates a negative pressure thread suction action.

1.2. The first needle 60 of the sewing machine moves downward, and the needle 60 carries the upper thread downward through the seam hook groove 21, as shown in Figure 4. Under the action of the rotary shuttle 70, the upper thread end on one side of the needle 60 is driven to the bottom of the movable knife 20.

1.3. The first needle 60 of the sewing machine moves upward. After the needle 60 moves upward away from the movable knife 20, the movable knife 20 rotates forward in the direction close to the starting thread trimming fixed knife 101. The view angle of Figure 1 is counterclockwise rotation. As shown in Figure 5, the needle thread head is pulled out upward and accommodated in the second thread receiving groove 26. The movable knife 20 rotates forward with the needle thread head until the starting thread trimming cutting edge 22 is close to the starting thread trimming fixed knife 101, but the two are not engaged. The first thread pressing part abuts against the second thread pressing part 41 to clamp the needle thread head in the second thread receiving groove 26; at the same time, the thread head end of the needle thread head in the second thread receiving groove 26 is just in the negative pressure area of the air suction port 51, so that the thread head end is picked up. At this time, the movable knife 20 and the starting thread trimming fixed knife 101 are in a non-engaged state, so the needle thread head is only clamped and not cut off.

1.4. The sewing machine continues to sew the second stitch, the third stitch, etc. until the set number of stitches is reached.

1.5. The movable knife 20 continues to rotate forward with the needle thread ends toward the direction close to the seam thread starting and trimming fixed knife 101 until the seam thread starting and trimming cutting edge 22 engages with the seam thread starting and trimming fixed knife 101 to cut off the needle thread ends in the second thread containing groove 26. The cut needle thread ends are sucked away and collected by the negative pressure of the suction port 51.

1.6. The movable knife 20 continues to rotate forward to its initial position, and the air suction port 51 of the air suction pipe 50 stops suctioning air.

2. The thread trimming device of the sewing machine is used to trim the thread at the end of sewing, including the following steps:

2.1. When the thread needs to be trimmed at the end of sewing, during the process of the sewing machine sewing the last stitch, after the needle 60 moves upward over the movable knife 20, the movable knife 20 rotates backward toward the direction of the fixed knife 102 for thread trimming after sewing. The viewing angle of Figure 1 is clockwise, as shown in Figure 6, and the dividing groove 24 realizes the hooking and dividing of the thread.

2.2. The movable knife 20 continues to rotate backward with the upper thread and the lower thread toward the post-sewing thread trimming fixed knife 102, and the upper thread and the lower thread are accommodated in the first thread accommodating groove 25 until the post-sewing thread trimming cutting edge 23 engages with the post-sewing thread trimming fixed knife 102, cutting off the upper thread and the lower thread in the first thread accommodating groove 25.

2.3. The movable knife 20 rotates forward to its initial position.

In summary, the utility model effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may 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 a person of ordinary skill in the art without departing from the spirit and technical concept disclosed in the present invention shall still be covered by the claims of the present invention.

Claims (13)

1. The utility model provides a sewing machine thread cutting device, includes stationary knife (10) of fixed setting and can be to being close to or keep away from stationary knife (10) direction motion move sword (20), the periphery of moving sword (20) has and distributes in sewing machine needle (60) under and needle point (30) that the position was confirmed, its characterized in that: the movable cutter (20) is provided with a seam lifting and hooking groove (21), a seam lifting and shearing edge (22) and a seam post-shearing edge (23), the seam lifting and hooking groove (21) penetrates through the movable cutter (20) along the thickness direction of the movable cutter (20) and allows a needle (60) to pass through, the seam lifting and shearing edge (22) and the seam post-shearing edge (23) can be engaged with the fixed cutter (10), and the seam lifting and shearing edge (22) is arranged close to the seam post-shearing edge (23); when the seam lifting cutting edge (22) is meshed with the fixed knife (10), the seam post cutting edge (23) is adjacent to the needle dropping point (30), and the seam lifting cutting edge (22) is adjacent to the needle dropping point (30).

2. The thread cutting device of a sewing machine of claim 1, wherein: the movable cutter (20) is an arc cutter body;

Along the circumferential direction of the movable knife (20), the circumferential distance between the starting seam cutting edge (22) and the post-seam cutting edge (23) is 0-6mm;

Along the axial direction of the movable knife (20), the axial distance between the seam starting cutting edge (22) and the seam finishing cutting edge (23) is 0-4mm.

3. The thread cutting device of a sewing machine of claim 1, wherein: when the seam starting cutting edge (22) is meshed with the fixed knife (10), the distance between the seam finishing cutting edge (23) and the needle falling point (30) is 1-6mm.

4. The thread cutting device of a sewing machine of claim 1, wherein: a wire dividing groove (24) is formed in the movable knife (20); when the seam-lifting cutting edge (22) is meshed with the fixed knife (10), the needle falling points (30) are distributed in the branching groove (24).

5. The thread cutting device of a sewing machine of claim 4, wherein: the movable knife (20) is provided with a first wire containing groove (25) on the surface facing the fixed knife (10), and two ends of the first wire containing groove (25) extend to a post-sewing cutting edge (23) and a wire dividing groove (24) respectively.

6. The thread cutting device of a sewing machine of claim 4, wherein: the surface of the movable knife (20) facing the fixed knife (10) is provided with a first cutting edge forming part (27) and a second cutting edge forming part (28), the seam starting cutting edge (22) is formed at the edge of the first cutting edge forming part (27), and the seam finishing cutting edge (23) is formed at the edge of the second cutting edge forming part (28);

The first cutting edge forming part (27) and the second cutting edge forming part (28) are distributed in a staggered mode, and the seam starting cutting edge (22) is distributed on one side, facing the parting groove (24), of the seam finishing cutting edge (23).

7. The thread cutting device of a sewing machine of claim 4, wherein: the surface of the movable knife (20) facing the fixed knife (10) is provided with a first cutting edge forming part (27) and a second cutting edge forming part (28), the seam starting cutting edge (22) is formed at the edge of the first cutting edge forming part (27), and the seam finishing cutting edge (23) is formed at the edge of the second cutting edge forming part (28);

The first cutting edge forming part (27) and the second cutting edge forming part (28) are the same cutting edge forming part, the seam starting cutting edge (22) is distributed on one side of the seam starting cutting edge (23) back to the branching groove (24), and the seam starting cutting edge (22) and the seam starting cutting edge (23) are distributed on the same circumference line of the movable cutter (20).

8. The thread cutting device of a sewing machine of claim 1, wherein: the movable knife (20) is provided with a second containing groove (26) facing the fixed knife (10), and two ends of the second containing groove (26) extend to the seam lifting hook groove (21) and the seam lifting shear line cutting edge (22) respectively.

9. The thread cutting device of a sewing machine of claim 1, wherein: the fixed knife (10) comprises a seam lifting cutting line fixed knife (101) and a seam post-cutting line fixed knife (102), wherein the seam lifting cutting line fixed knife (101) is distributed on one side of the machine needle (60) and can be meshed with the seam lifting cutting line cutting edge (22), and the seam post-cutting line fixed knife (102) is distributed on the other side of the machine needle (60) and can be meshed with the seam post-cutting line cutting edge (23).

10. The thread cutting device of a sewing machine of claim 9, wherein: the sewing machine also comprises a thread pressing plate (40) which is fixedly arranged, wherein the thread pressing plate (40), the seam lifting and cutting fixed knife (101) and the movable knife (20) are sequentially arranged from outside to inside along the radial direction of a rotating shuttle (70) in the sewing machine; the movable knife (20) is provided with a first line pressing part, and the line pressing plate (40) is provided with a second line pressing part (41) distributed on the outer end side of the seam starting, shearing and line fixing knife (101);

When the seam lifting cutting edge (22) is adjacent to the seam lifting cutting fixed knife (101) and is not meshed, the first line pressing part is abutted with the second line pressing part (41) and forms a line clamping seam for clamping the upper line.

11. The thread cutting device of a sewing machine of claim 9, wherein: the movable knife (20) is provided with a first line pressing part, and the seam lifting and trimming fixed knife (101) is provided with a third line pressing part;

When the seam lifting cutting edge (22) is adjacent to the seam lifting cutting fixed knife (101) and is not meshed, the first line pressing part is abutted with the third line pressing part, and a line clamping seam for clamping the upper line is formed.

12. The thread cutting device of a sewing machine of claim 9, wherein: the sewing machine also comprises an air suction pipe (50) which is fixedly arranged, the air suction pipe (50) is provided with an air suction opening (51) which is aligned with the seam lifting and hooking groove (21), and the seam lifting and cutting fixed knife (101), the air suction opening (51) and the movable knife (20) are sequentially arranged from outside to inside along the radial direction of the rotating shuttle (70) in the sewing machine.

13. A sewing machine, characterized in that: the sewing machine equipped with the sewing machine thread cutting device according to any one of claims 1 to 12.