CN221254877U - A bird nest prevention movable knife and sewing machine thread cutting mechanism - Google Patents

Abstract

The utility model provides a bird nest preventing movable knife and a sewing machine thread cutting mechanism, wherein the bird nest preventing movable knife comprises a movable knife body, needle falling positions which are distributed right below a needle in a sewing machine and are positioned in a certain position are arranged on the periphery of the movable knife body, a suture lifting groove allowing the needle to pass through, a suture lifting cutting edge and a thread dividing groove for cutting off a thread head of an upper thread, and a suture post-cutting edge for cutting off the upper thread and a bottom thread are arranged on the movable knife body, the suture lifting groove and the thread dividing groove are distributed between the suture post-cutting edge and the suture lifting cutting edge, the suture lifting cutting edge is arranged on a first needle falling side of the movable knife body, and the side of the movable knife body is close to the needle falling position when the suture lifting cutting edge cuts the thread head of the upper thread, so that the suture lifting cutting edge is also close to the needle falling position when the suture lifting cutting edge is used for cutting the upper thread, and the length of the upper thread remaining on a suture is shortened. The utility model can also set the space between the thread dividing groove and the thread cutting edge after sewing as the optimal space, and avoid the too short thread end of the bottom thread on the rotating shuttle after sewing and thread cutting.

Description

A bird nest prevention movable knife and sewing machine thread cutting mechanism

Technical Field

The utility model relates to the technical field of sewing machines, in particular to an anti-bird nest movable knife and a sewing machine thread cutting mechanism comprising the anti-bird nest movable knife.

Background technique

A sewing machine is a machine that uses one or more sewing threads to form one or more stitches on fabrics to interweave or sew one or more layers of fabrics. A sewing machine is usually composed of a feeder, a base, a transmission, and accessories. Through the reasonable coordination of the movements of each mechanism and the cyclic work, the sewing materials are sewn together.

In order to improve sewing efficiency, sewing machines are usually equipped with automatic thread cutting devices, which are used to automatically cut the suture threads (i.e., the upper thread and the lower thread) at the end of sewing. In this way, not only the sewing is smooth, but also the thread ends in the clothes are reduced, thereby improving the efficiency of subsequent finishing. However, during the sewing process, the existing automatic thread cutting device can only cut the suture threads after the sewing process is completed, so that a certain length of upper thread ends (also called needle thread ends) remain on one side of the machine needle; during the second needle sewing, the needle thread ends will form bird's nest-shaped thread ends on the sewn clothes, affecting the quality of the entire clothes, thereby affecting the quality of the entire clothes. In order to ensure the quality of the clothes, the bird's nest-shaped thread ends must be manually trimmed, which increases the intensity of labor and affects production efficiency.

In order to solve the above problems, some sewing machines in the prior art are equipped with a thread trimming mechanism, which can not only realize the capture of the upper thread at the start of sewing, but also realize automatic thread trimming at the end of sewing. For example: a sewing dynamic knife structure and its thread cutting device disclosed in the Chinese utility model patent with application number 202211272392.8, controls the movement of the moving knife body through a control system to realize the capture of the upper thread head at the start of sewing, and the captured upper thread head slides along one side of the needle groove to the cutting edge, and the upper thread head is cut off by the engagement of the cutting edge and the fixed knife. However, since the cutting position of the upper thread head is far away from the needle drop position, the upper thread head remaining on the sewing material is relatively long, and manual trimming is still required. If the cutting position of the upper thread head is set to be close to the needle drop position, it is bound to shorten the length of the thread groove after sewing, destroying the thread groove after sewing, resulting in a shorter length of the bottom line head on the rotary shuttle after thread trimming at the end of sewing, which is very likely to cause the undesirable phenomenon of not being able to bring the bottom line when sewing next time. In addition, the sewing machine knife structure sets the needle groove and the cutting edge in the same groove body, resulting in the inability to pull out the excess upper thread ends after the upper thread ends are captured, which easily leads to the undesirable phenomenon that the upper thread ends are entangled in the normal stitches again, which is not conducive to the collection of the thread ends after cutting.

Utility Model Content

In view of the shortcomings of the prior art mentioned above, the technical problem to be solved by the utility model is to provide an anti-bird's nest movable knife, which can not only make the upper thread end remaining on the sewing material shorter after thread cutting at the beginning of sewing, but also prevent the lower thread end on the rotary shuttle from being too short after thread cutting at the end of sewing.

To achieve the above-mentioned purpose, the utility model provides an anti-bird's nest movable knife, including a movable knife body, the periphery of the movable knife body has a needle drop position distributed directly below the needle in the sewing machine and with a fixed position, the movable knife body is provided with a seam start hook groove allowing the needle to pass through, a seam start thread cutting blade for cutting the upper thread end, a wire dividing groove, and a post-sewing thread cutting blade for cutting the upper thread and the lower thread, the seam start hook groove and the wire dividing groove are distributed between the post-sewing thread cutting blade and the seam start thread cutting blade, the seam start thread cutting blade is arranged on the first needle drop side of the movable knife body, and the first needle drop side is the side of the movable knife body close to the needle drop position when the seam start thread cutting blade cuts the upper thread end.

Furthermore, the movable blade body is an arc blade body;

Along the circumference of the movable knife body, the thread cutting blade after sewing, the thread hooking groove at the beginning of sewing, the thread dividing groove and the thread cutting blade at the beginning of sewing are distributed on the same circumference line of the movable knife body.

Furthermore, the wire dividing groove is distributed between the seam starting wire hook groove and the seam starting wire cutting blade, and the post-sewing wire cutting blade is arranged at one end of the seam starting wire hook groove away from the wire dividing groove.

Furthermore, the wire dividing groove is distributed between the thread cutting blade after sewing and the thread hooking groove for starting sewing.

Furthermore, the post-sewing thread trimming blade is arranged adjacent to the second needle dropping side of the movable knife body, and the second needle dropping side is the side of the movable knife body adjacent to the needle dropping position when the post-sewing thread trimming blade cuts the upper thread and the lower thread.

Furthermore, a thread-accommodating groove for starting a seam and a thread-accommodating groove for accommodating a thread after seam are provided on the surface of the movable blade body. The thread-accommodating groove for starting a seam is connected between the thread-hooking groove for starting a seam and the thread-cutting blade for starting a seam, and the thread-accommodating groove for accommodating a thread after seam is connected between the thread-dividing groove and the thread-cutting blade after seam.

Furthermore, the movable knife body is provided with a thread cutting and dividing tip at the first needle dropping side, and the thread cutting and dividing tip is in a triangular shape.

The utility model also provides a thread trimming mechanism for a sewing machine, comprising a seam start cutting knife, a post-sewing cutting knife, and the above-mentioned anti-bird nest movable knife, wherein the anti-bird nest movable knife can reciprocate between the seam start cutting knife and the post-sewing cutting knife, the seam start cutting blade can engage with the seam start cutting knife, and the post-sewing cutting blade can engage with the post-sewing cutting knife.

Furthermore, the seam-starting cutter and the seam-post-cutting cutter are both fixed knives, and the seam-starting cutter and the seam-post-cutting cutter are respectively distributed on both sides of the machine needle.

Furthermore, the thread trimming mechanism of the sewing machine also includes a fixed suction pipe, the suction pipe and the seam starter cutter are distributed on the same side of the machine needle, the suction pipe has a suction port aligned with the surface of the movable knife body, and the seam starter cutter, the suction port and the anti-bird's nest movable knife are arranged in sequence from the outside to the inside along the radial direction of the rotary shuttle in the sewing machine.

Furthermore, the thread trimming mechanism of the sewing machine further comprises a fixedly arranged thread pressing plate, the thread pressing plate and the seam starting cutter are distributed on the same side of the machine needle, and the thread pressing plate, the seam starting cutter and the anti-bird nest 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 thread pressing plate is provided with a first thread pressing portion distributed on the outer end side of the seam starting cutter, and the movable knife body is provided with a second thread pressing portion;

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

Furthermore, the wire pressing plate and the seam cutting knife are both provided with tooth avoidance grooves.

Furthermore, the movable knife body is provided with a second pressing portion, and the seam cutting knife is provided with a third pressing portion;

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

Furthermore, the movable knife body is provided with a first knife lifting portion and a second knife lifting portion, the first knife lifting portion acts on the seam cutting knife, and the second knife lifting portion acts on the seam post-cutting knife.

As described above, the bird nest prevention movable knife and sewing machine thread cutting mechanism of the utility model have the following beneficial effects:

1. The present application arranges the seam start thread cutting blade at the first needle drop side of the movable knife body. In this way, when the upper thread end is cut off by the seam start thread cutting blade at the start of sewing, since the first needle drop side is close to the needle drop position, the seam start thread cutting blade is also close to the needle drop position, which makes the seam start thread cutting blade very close to the machine needle, thereby shortening the length of the upper thread end remaining on the sewing material after the seam start thread cutting.

2. Since the thread cutting effect of the short thread head at the start of sewing is achieved by setting the thread cutting blade at the first needle drop side of the movable knife body, it is not affected by the distribution position of the dividing groove and the thread cutting blade after sewing, so that the distance between the dividing groove and the thread cutting blade after sewing can be set to the optimal distance, avoiding the bottom thread head on the rotary shuttle being too short after thread cutting at the end of sewing, so that the bottom thread head on the rotary shuttle has a certain length, which can be reliably interwoven with the surface thread to form a stitch at the next start of sewing.

3. This structure can also ensure a certain distance between the seam start hook groove and the seam start cutting blade, so that a part of the upper thread end can be reliably pulled out, effectively preventing the upper thread end from being entangled again.

BRIEF DESCRIPTION OF THE DRAWINGS

1 to 3 are schematic diagrams showing the process of starting sewing and cutting the thread by the thread cutting mechanism of the sewing machine of the present application.

(The anti-bird nest movable knife in FIG1 is in the seam start hooking position, the anti-bird nest movable knife in FIG2 is in the seam start cutting waiting position, and the anti-bird nest movable knife in FIG3 is in the seam start cutting completion position.)

4 to 5 are schematic diagrams showing the thread trimming process after sewing by the thread trimming mechanism of the sewing machine of the present application.

(Wherein, the anti-bird nest movable knife in FIG. 4 is in the line cutting and dividing position after sewing, and the anti-bird nest movable knife in FIG. 5 is in the line cutting completion position after sewing.)

FIG6 a is a schematic structural diagram of the first embodiment of the anti-bird nest movable knife in the present application, in which the anti-bird nest movable knife is in the seam starting and line cutting position.

FIG6 b is a schematic structural diagram of the second embodiment of the anti-bird nest movable knife in the present application, in which the anti-bird nest movable knife is in the seam starting and cutting position.

FIG. 7 is a schematic diagram of the structure of the seam cutting knife in the present application.

FIG8 is a schematic diagram of the structure of the voltage board in the present application.

Component number description

10 Needle

20 Movable blade

21 Seam hook groove

22 Seam cutting blade

23 branch slot

24 Seam trimmer blade

25 First needle drop side

26 Second needle drop side

27 Seam-forming duct

28 Seam back wire slot

29 Thread cutting tip

210 Second crimping section

211 First Knife Lifting Department

212 Second knife lifter

30 Needle drop position

40 Seam cutting knife

50 Seam cutter

60 Suction pipe

61 Air intake

70 Pressing plate

71 First crimping section

80 Tooth avoidance groove

90 Base Plate

110 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 relates to the technical field of sewing machines, and in particular to an anti-bird nest movable knife, and a sewing machine thread trimming mechanism including the anti-bird nest movable knife. Usually, a sewing machine is provided with a needle 10 that can reciprocate up and down, and a rotatable shuttle 110. In the following embodiments, the axial direction of the shuttle 110 is defined as the left-right direction, the extending direction of the needle 10 is defined as the up-down direction, the direction orthogonal to both the left-right direction and the up-down direction is defined as the front-back direction, and the front direction is the moving direction of the sewing material when the sewing machine is sewing.

As shown in FIG. 6a or FIG. 6b, the bird nest prevention movable knife involved in the utility model includes a movable knife body 20, on which a seam start hooking groove 21, a seam start cutting blade 22, a dividing groove 23 and a post-sewing cutting blade 24 are provided. The seam start hooking groove 21 penetrates the movable knife body 20 along the thickness direction of the movable knife body 20, the seam start hooking groove 21 allows the needle 10 in the sewing machine to pass through, the seam start cutting blade 22 is used to cut off the upper thread end when sewing, and the dividing groove 23 is used to cut the thread after sewing. When the thread is divided, the thread cutting blade 24 after sewing is used to cut the upper thread and the lower thread when the thread is cut at the end of sewing. The thread hooking groove 21 and the thread dividing groove 23 are distributed between the thread cutting blade 24 after sewing and the thread cutting blade 22 after sewing. The thread cutting blade 24 after sewing, the thread hooking groove 21 after sewing, the thread dividing groove 23 and the thread cutting blade 22 after sewing can be distributed in sequence as shown in Figure 6a, or the thread cutting blade 24 after sewing, the thread dividing groove 23, the thread hooking groove 21 after sewing and the thread cutting blade 22 after sewing can be distributed in sequence as shown in Figure 6b. Except for the first stitch of the sewing machine, that is, the sewing machine starts from the second stitch, the movable knife body 20 is distributed on the front side or the rear side of the machine needle 10 to avoid interference with the up and down reciprocating movement of the machine needle 10. In this way, the outer periphery of the movable knife body 20 has a needle drop position 30 distributed directly below the needle 10 in the sewing machine. The needle drop position 30 is the position of the needle 10 on the extended surface of the movable knife body 20 during the up and down reciprocating movement of the needle 10, so the position of the needle drop position 30 is fixed.

As shown in Figure 1, the sewing machine thread trimming mechanism involved in the present application includes a seam start cutter 40, a seam post-sewing cutter 50, and the above-mentioned anti-bird nest movable knife. The anti-bird nest movable knife can reciprocate between the seam start cutter 40 and the seam post-sewing cutter 50, so that the seam start cutter blade 22 is engaged with the seam start cutter 40, and the seam post-sewing cutter blade 24 is engaged with the seam post-sewing cutter 50.

Preferably, the seam start cutter 40 and the seam back cutter 50 are fixed fixed cutters, and the seam start cutter 40 and the seam back cutter 50 are respectively distributed on the front and rear sides of the machine needle 10. In the embodiment of the thread trimming mechanism of the sewing machine shown in Figures 1 to 5, the seam start cutter 40 is distributed on the front side of the machine needle 10, and the seam back cutter 50 is distributed on the rear side of the machine needle 10, then the seam back cutter blade 24, the seam start hook groove 21, the line dividing groove 23 and the seam start cutter blade 22 are distributed in sequence from front to back, and the seam start cutter 40 and the seam back cutter 50 are both fixed to the bottom of the bottom plate 90 of the sewing machine. Alternatively, the seam start cutter 40 can be distributed on the rear side of the machine needle 10, and the seam back cutter 50 can be distributed on the front side of the machine needle 10, then the seam back cutter blade 24, the seam start hook groove 21, the line dividing groove 23 and the seam start cutter blade 22 are distributed in sequence from back to front.

In other embodiments, the seam starter cutter 40 and the seam back cutter 50 are both movable relative to the bottom plate 90. The following description of the thread trimming mechanism and the anti-bird nest movable knife of the sewing machine is carried out by taking the seam starter cutter 40 and the seam back cutter 50 as fixed knives, the seam starter cutter 40 being arranged at the front side of the machine needle 10, and the seam back cutter 50 being arranged at the rear side of the machine needle 10 as an example.

When the thread trimming mechanism of the sewing machine starts sewing and trimming the thread, first, before the sewing machine starts sewing the first stitch, or during the process of the sewing machine needle 10 moving down for the first stitch, the anti-bird nest movable knife moves to the sewing thread hooking position, so that the sewing thread hooking groove 21 moves to the needle drop position 30, that is, the sewing thread hooking groove 21 moves to the bottom of the needle 10, as shown in FIG1. Secondly, during the process of the sewing machine needle 10 moving down for the first stitch, the needle 10 passes the upper thread downward through the sewing thread hooking groove 21, and combined with the rotation of the rotary hook 110, the rotary hook 110 hooks the upper thread end, as shown in FIG1. Then, the sewing machine starts sewing with the first needle 10 moving upwards. When the needle 10 moves upwards away from the anti-bird nest movable knife, the anti-bird nest movable knife moves forward in the direction close to the seam start cutting knife 40 until it moves to the seam start cutting line waiting position. At this time, as shown in FIG. 2 , the seam start cutting line blade 22 is close to the seam start cutting knife 40, but the two are not engaged, and the rear side of the movable knife body 20 is distributed in front of the needle drop position 30 and is close to the needle drop position 30. The rear side of the movable knife body 20 is defined as the first needle drop side 25; during this process, the anti-bird nest movable knife pulls out the upper thread. Then, the sewing machine starts sewing the second stitch, the third stitch, ..., until the set number of stitches is reached. During this process, the needle 10 moves back and forth up and down on the rear side of the first needle drop side 25. Afterwards, the anti-bird's nest movable knife continues to move forward in the direction close to the seam start cutter 40 until it moves to the seam start cutting position, and the seam start cutting blade 22 and the seam start cutter 40 engage to cut the surface thread end. At this time, the first needle drop side 25 of the movable knife body 20 is close to the needle drop position 30 and is very close to the machine needle 10.

In the anti-bird nest movable knife involved in the present application, as shown in Figure 6a or 6b, the seam start thread cutting blade 22 is set at the first needle drop side 25 of the movable knife body 20. In this way, when the seam start thread cutting blade 22 and the seam start cutting knife 40 bite and cut the upper thread end, since the first needle drop side 25 is close to the needle drop position 30 at this time, the seam start thread cutting blade 22 is also close to the needle drop position 30, which makes the seam start thread cutting blade 22 very close to the machine needle 10, so that the length of the upper thread end remaining on the sewing material after the seam start thread cutting can be shortened, and the seam start thread cutting effect of short thread ends can be achieved. Moreover, the thread cutting effect of the short thread head at the start of sewing is achieved by setting the thread cutting blade 22 at the first needle drop side 25 of the movable blade body 20, which is not affected by the distribution position of the dividing groove 23 and the thread cutting blade 24 after sewing, so that the spacing between the dividing groove 23 and the thread cutting blade 24 after sewing can be set to the optimal spacing, avoiding the bottom line thread head on the rotary shuttle 110 being too short after the thread cutting is completed at the end of sewing, so that the bottom line thread head on the rotary shuttle 110 has a certain length, and can reliably interweave with the surface thread to form a stitch when sewing next time. In addition, this structure can also ensure that there is a certain distance between the thread hook groove 21 and the thread cutting blade 22 at the start of sewing, and can reliably pull out a part of the surface thread head, effectively preventing the surface thread head from being entangled again.

When the thread trimming mechanism of the sewing machine finishes thread trimming, first, after the last needle 10 of the sewing machine moves up, the anti-bird nest movable knife moves backward in the direction close to the back-seam cutter 50 until it moves to the back-seam cutter line separation position, as shown in FIG4 , and the line is hooked and separated by the line separation groove 23. After that, the anti-bird nest movable knife continues to move backward in the direction close to the back-seam cutter 50 until it moves to the back-seam cutter line position, and then the back-seam cutter blade 24 and the back-seam cutter 50 bite and cut the upper thread and the lower thread. At this time, the front side of the movable knife body 20 is distributed on the rear side of the needle drop position 30 and is close to the needle drop position 30, and the front side of the movable knife body 20 is defined as the second needle drop side 26. After the upper thread and the lower thread are cut, since the spacing between the line separation groove 23 and the back-seam cutter blade 24 can ensure that the lower thread head on the rotary hook 110 has a certain length, the undesirable phenomenon of the lower thread not being brought up will not occur when sewing next time.

Furthermore, in the present application, the movement mode of the movable blade 20 is: rotating around the rotary shuttle 110. Based on this, the thread trimming mechanism of the sewing machine also includes a thread trimming drive source and a thread trimming transmission mechanism. The thread trimming drive source is a motor, preferably a stepping motor. The thread trimming drive source is connected to the movable blade 20 through the thread trimming transmission mechanism to drive the movable blade 20 to rotate forward or backward. In addition, the thread trimming drive source is communicatively connected to the control system of the sewing machine. The control system of the sewing machine realizes the functions of thread trimming at the start of sewing to prevent bird nests, and automatic thread trimming at the end of sewing by controlling the action of the thread trimming drive source.

Furthermore, based on the different positions of the seam start hooking groove 21 and the line dividing groove 23, there are two embodiments of the anti-bird nest movable knife. Anti-bird nest movable knife embodiment 1: As shown in FIG6a, the thread cutting blade 24 after sewing, the seam start hooking groove 21, the line dividing groove 23 and the seam start cutting blade 22 are arranged in sequence. Anti-bird nest movable knife embodiment 2: As shown in FIG6b, the thread cutting blade 24 after sewing, the line dividing groove 23, the seam start hooking groove 21 and the seam start cutting blade 22 are arranged in sequence. The remaining structures of the anti-bird nest movable knife embodiments 1 and 2 are the same.

Further, as shown in Fig. 6a or Fig. 6b, the movable blade 20 is an arc blade, which extends along the rotation direction of the movable blade 20. Along the circumference of the movable blade 20, the post-sewing thread cutting blade 24, the seam start thread hooking groove 21, the line dividing groove 23 and the seam start thread cutting blade 22 are distributed on the same circumference of the movable blade 20, and there is no misalignment relationship in the left-right direction.

Furthermore, in the first embodiment of the anti-bird nest movable knife, as shown in FIG6a, the seam start hooking groove 21 is arranged close to the front side (i.e., the second needle drop side 26) of the movable knife body 20, and the post-sewing thread cutting blade 24 is arranged at the front end of the seam start hooking groove 21 away from the line dividing groove 23, so that the post-sewing thread cutting blade 24 is arranged adjacent to the second needle drop side 26 of the movable knife body 20. In the second embodiment of the anti-bird nest movable knife, as shown in FIG6b, the post-sewing thread cutting blade 24 is arranged directly adjacent to the second needle drop side 26 of the movable knife body 20. In this way, when the upper thread and the lower thread are cut by the post-sewing thread trimming blade 24 and the post-sewing cutting knife 50 after sewing is finished, since the post-sewing thread trimming blade 24 is close to the second needle dropping side 26 of the movable knife body 20 at this time, and the second needle dropping side 26 is close to the needle dropping position 30 at this time, the post-sewing thread trimming blade 24 is also close to the needle dropping position 30, which makes the post-sewing thread trimming blade 24 very close to the machine needle 10, so that the length of the bottom thread end remaining on the sewing material after the thread trimming is finished, and the post-sewing thread trimming effect of short thread ends is achieved.

Further, as shown in FIG6a or FIG6b, the upper surface of the movable knife body 20 is provided with a seam start thread groove 27 and a seam back thread groove 28, the seam start thread groove 27 is connected between the seam start hook thread groove 21 and the seam start thread cutting blade 22, and the seam back thread groove 28 is connected between the wire dividing groove 23 and the seam back thread cutting blade 24. In the first embodiment of the anti-bird nest movable knife, as shown in FIG6a, the seam back thread groove 28 is the front section of the seam start thread groove 27; and, based on the structure that the seam back thread cutting blade 24 is arranged at the front end of the seam start hook thread groove 21, the seam start thread groove 27 is connected between the seam back thread cutting blade 24 and the seam start thread cutting blade 22. In the second embodiment of the anti-bird nest movable knife, as shown in FIG6b, the thread groove 27 for starting the seam and the thread groove 28 for ending the seam are two groove bodies, and the thread groove 27 for starting the seam is distributed on the rear side of the thread groove 28 for ending the seam. The thread groove 27 for starting the seam and the thread groove 28 for ending the seam can be set to be disconnected or connected. When cutting the thread at the start of the seam, the upper thread end pulled out is accommodated in the thread groove 27 for starting the seam to prevent the upper thread end from being entangled under the movable knife body 20 again. When cutting the thread after the seam, a section of the bottom thread and the top thread are accommodated in the thread groove 28 for ending the seam, and the spacing between the dividing groove 23 and the thread cutting blade 24 for ending the seam is also the length of the thread groove 28 for ending the seam, and the length of the thread groove 28 for ending the seam directly determines the length of the bottom thread end on the rotary hook 110 after the thread cutting is completed at the end of sewing. The present application will not damage the post-sewing thread groove 28, so that the post-sewing thread groove 28 has an optimal length, and accurately controls the remaining length of the bottom thread head on the rotary hook 110 after the sewing is completed and the thread is trimmed.

Further, as shown in Fig. 6a or Fig. 6b, the movable knife body 20 is provided with a thread cutting and dividing tip 29 at the first needle drop side 25, and the thread cutting and dividing tip 29 is in a triangular shape with a sharp corner facing backward. When cutting the thread after sewing, the thread cutting and dividing tip 29 first passes through the upper thread loop to ensure the accuracy of the upper thread dividing.

Further, as shown in FIG. 1 and FIG. 2 , the thread trimming mechanism of the sewing machine also includes a fixedly arranged air suction pipe 60, and the air suction pipe 60 and the seam start cutting knife 40 are distributed on the same side of the machine needle 10, and the air suction pipe 60 is arranged on the front side of the machine needle 10, and the seam start cutting knife 40, the air suction port 61 and the anti-bird nest movable knife are arranged in sequence from the outside to the inside along the radial direction of the rotary shuttle 110 in the sewing machine. The air suction pipe 60 has an air suction port 61 aligned with the surface of the movable knife body 20, and the air suction port 61 is preferably aligned with the seam start hook groove 21 and/or the seam start containing groove 27, and the air suction port 61 is used to pre-collect the thread end of the upper thread before the upper thread end is cut off, and to collect the upper thread end after the upper thread end is cut off. Preferably, the air suction pipe 60 is fixed to the bottom of the sewing machine bottom plate 90.

Furthermore, when the seam is cut, the anti-bird nest movable knife moves to the seam cutting waiting position shown in FIG. 2, and the seam cutting blade 22 is close to the seam cutting knife 40, but the two are not engaged, and the upper thread end is in a clamped state, so that when the number of stitches is set at the beginning of the seam, the upper thread end can be reliably prevented from being separated. Based on this, the upper thread end can be clamped in the following two ways.

Method 1: As shown in FIG. 1 and FIG. 2, the thread trimming mechanism of the sewing machine further includes a fixedly arranged thread pressing plate 70, and the thread pressing plate 70 and the seam start cutting knife 40 are distributed on the same side of the machine needle 10, then the thread pressing plate 70 is arranged on the front side of the machine needle 10, and the thread pressing plate 70, the seam start cutting knife 40 and the anti-bird nest movable knife are arranged in sequence from the outside to the inside along the radial direction of the rotary shuttle 110 in the sewing machine. The thread pressing plate 70 is provided with a first thread pressing portion 71 distributed on the outside of the rear end of the seam start cutting knife 40, and the movable knife body 20 is provided with a second thread pressing portion 210, and the second thread pressing portion 210 is distributed on the rear side of the seam start cutting knife 22 and is close to the seam start cutting knife 22. When the seam start cutting knife 22 is adjacent to the seam start cutting knife 40 and is not engaged, the second thread pressing portion 210 abuts against the first thread pressing portion 71 and forms a thread clamping seam for clamping the upper thread, and the thread end of the upper thread is clamped by the thread pressing plate 70 and the anti-bird nest movable knife. Preferably, the thread pressing plate 70 is fixed to the bottom of the sewing machine bottom plate 90 .

Method 2: The movable blade body 20 is provided with a second thread pressing portion 210, and the seam starter cutter 40 is provided with a third thread pressing portion. When the seam starter cutter blade 22 is close to the seam starter cutter 40 and is not engaged, the second thread pressing portion 210 abuts against the first thread pressing portion 71 and forms a thread clamping seam for clamping the upper thread, and the upper thread end is clamped by the seam starter cutter 40 and the anti-bird nest movable blade. Method 2 can also be considered as: the thread pressing plate 70 and the seam starter cutter 40 are set as one body.

Preferably, as shown in FIG. 6a or FIG. 6b, the movable blade body 20 is provided with a first blade lifting portion 211 and a second blade lifting portion 212; the first blade lifting portion 211 is provided at the front side of the movable blade body 20, and the first blade lifting portion 211 acts on the seam starter knife 40, and can slightly lift the seam starter knife 40 upward, so that the seam starter knife 40 can better cooperate with the seam starter thread cutting blade 22; the second blade lifting portion 212 is provided at the rear side of the movable blade body 20, and the second blade lifting portion 212 acts on the back seam cutter 50, and can slightly lift the back seam cutter 50 upward, so that the back seam cutter 50 can better cooperate with the back seam thread cutting blade 24. As shown in FIG. 7 and FIG. 8, the thread pressing plate 70 and the seam starter knife 40 are both provided with a tooth avoidance groove 80, and the provision of the tooth avoidance groove 80 can prevent the thread pressing plate 70 and the seam starter knife 40 from interfering with the movement of the feed dog in the sewing machine, thereby achieving common use of multiple models. In this embodiment, the tooth avoidance groove 80 on the wire pressing plate 70 is a through groove structure that passes through from top to bottom, and the tooth avoidance groove 80 on the seam cutting knife 40 is a sunken groove structure that does not pass through from top to bottom.

In summary, taking the embodiment 1 of the anti-bird nest movable knife configured with the thread pressing plate 70 and FIG. 6 a in the thread trimming mechanism of the sewing machine as an example, the working process of the present application when starting to sew and trimming the thread includes the following steps.

1.1. Before the sewing machine starts sewing the first stitch, or when the sewing machine needle 10 moves down, the anti-bird's nest movable knife rotates to the sewing thread hooking position, as shown in FIG. 1 , so that the sewing thread hooking groove 21 rotates to the bottom of the sewing needle 10.

1.2. The sewing machine needle 10 moves downward when starting to sew the first stitch. The needle 10 carries the upper thread downward through the sewing thread hook groove 21. Under the action of the rotary shuttle 110, the upper thread end on one side of the needle 10 is brought to the bottom of the anti-bird nest movable knife, as shown in Figure 1.

1.3. The first needle 10 of the sewing machine moves upward. When the needle 10 moves upward away from the anti-bird nest movable knife, the anti-bird nest movable knife rotates forward to the waiting position for the thread cutting at the start of sewing. The upper thread end is drawn out and accommodated in the thread holding groove 27 for the start of sewing. As shown in FIG. 2, at this time, the thread cutting blade 22 of the start of sewing is close to the seam cutting knife 40, but the two are not engaged, and the first thread pressing part 71 of the thread pressing plate 70 and the second thread pressing part 210 of the anti-bird nest movable knife cooperate to clamp the thread end of the upper thread; at the same time, the rotary shuttle 110 rotates synchronously to remove the thread, and a negative pressure area is formed at the suction port 61 of the suction pipe 60 to pick up the thread end of the upper thread. Therefore, the thread end of the upper thread is in a state of not being cut off but being clamped, and the thread end is picked up by the suction port 61.

1.4. The sewing machine starts sewing the second stitch, the third stitch, ..., and the needle 10 reciprocates up and down on the rear side of the first needle drop side 25 until the set number of stitches is reached.

1.5. The anti-bird nest movable knife continues to rotate forward in the direction close to the seam start cutting knife 40 until it rotates to the seam start cutting position, and then the seam start cutting blade 22 and the seam start cutting knife 40 bite and cut the upper thread ends, and the cut upper thread ends are sucked away and collected through the suction pipe 60. Since the cutting positions of the seam start cutting blade 22 and the seam start cutting knife 40 are very close to the needle drop position 30, the upper thread ends remaining on the sewing material are very short.

1.6. The anti-bird nest movable knife continues to rotate forward to the initial position, as shown in FIG3 , and the anti-bird nest movable knife remains in the initial position, which is the position where the seam start and thread trimming are completed.

The working process of the present application when cutting the thread at the end of sewing includes the following steps.

2.1. The anti-bird's nest movable knife rotates backward toward the direction close to the post-seam cutting knife 50, and first the thread cutting and dividing tip 29 passes through the upper thread loop; as the anti-bird's nest movable knife continues to rotate backward, the bottom thread and the upper thread on the cut side slide into the dividing groove 23, as shown in FIG. 4; thereafter, the bottom thread and the upper thread are accommodated in the post-seam thread accommodating groove 28.

2.2. The anti-bird nest movable knife continues to rotate backwards toward the direction close to the post-sewing cutter 50 until it rotates to the post-sewing thread cutting position, and the post-sewing thread cutting blade 24 and the post-sewing cutter 50 bite and cut the upper thread and the lower thread. Since the thread cutting positions of the post-sewing thread cutting blade 24 and the post-sewing cutter 50 are very close to the needle drop position 30, the upper thread and the lower thread ends remaining on the sewing material are very short.

2.3. When the sewing machine is set to open the bird's nest function, after the thread trimming after sewing is completed, the anti-bird's nest movable knife remains on the rear side of the machine needle 10, that is, remains at the position where the thread trimming after sewing is completed, as shown in Figure 5. In this way, the thread hook groove 21 for sewing is very close to the needle drop position 30. When sewing is started next time, the anti-bird's nest movable knife turns forward at a small angle, so that the thread hook groove 21 for sewing can be rotated to the needle drop position 30, so that the thread hook groove 21 can be quickly rotated to the right below the machine needle 10 when sewing is started next time, avoiding the undesirable phenomenon that the machine needle 10 moves down and accidentally hits the movable knife body 20. When the sewing machine is set to close the bird's nest function for sewing, after the thread trimming after sewing is completed, the anti-bird's nest movable knife rotates forward to the initial position and stays on the front side of the machine needle 10 to ensure the thread splitting and thread trimming action when the thread trimming is completed at the end of sewing next time. Therefore, through the structural settings of various parts on the anti-bird's nest movable knife, the anti-bird's nest movable knife can be kept in the most effective working position according to different working modes to ensure the stability of the work.

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 (14)

1. The utility model provides a prevent bird's nest activity sword, includes activity cutter body (20), the periphery of activity cutter body (20) has and distributes in sewing machine needle (10) under and needle position (30) that fall of position determination, be equipped with on activity cutter body (20) and allow play seam hooking groove (21) that needle (10) passed through, be used for cutting off the play seam shearing sword (22) of upper thread end of a thread, branch groove (23) and be used for cutting off upper thread and bottom line seam back shearing sword (24), its characterized in that: the seam lifting and hooking groove (21) and the branching groove (23) are distributed between the seam lifting and shearing edge (24) and the seam lifting and shearing edge (22), the seam lifting and shearing edge (22) is arranged on a first needle falling side (25) of the movable cutter body (20), and the first needle falling side (25) is the side, close to the needle falling position (30), of the movable cutter body (20) when the seam lifting and shearing edge (22) cuts off the upper thread head.

2. The bird nest preventing movable knife according to claim 1, wherein: the movable cutter body (20) is an arc cutter body;

Along the circumference of the movable cutter body (20), the post-sewing thread cutting edge (24), the seam lifting thread hooking groove (21), the thread dividing groove (23) and the seam lifting thread cutting edge (22) are distributed on the same circumference of the movable cutter body (20).

3. The bird nest preventing movable knife according to claim 1, wherein: the parting grooves (23) are distributed between the seam lifting and hooking grooves (21) and the seam lifting and shearing edges (22), and the seam rear shearing edges (24) are arranged at one end of the seam lifting and hooking grooves (21) far away from the parting grooves (23).

4. The bird nest preventing movable knife according to claim 1, wherein: the parting grooves (23) are distributed between the post-sewing thread cutting edges (24) and the seam starting thread hooking grooves (21).

5. The bird nest preventing movable knife as claimed in any one of claims 1 to 4, wherein: the second needle dropping side (26) of the movable cutter body (20) is adjacent to the post-sewing thread cutting edge (24), and the second needle dropping side (26) is the side of the movable cutter body (20) which is close to the needle dropping position (30) when the post-sewing thread cutting edge (24) cuts off the upper thread and the bottom thread.

6. The bird nest preventing movable knife as claimed in any one of claims 1 to 4, wherein: the surface of the movable cutter body (20) is provided with a seam-lifting line-containing groove (27) and a seam-rear line-containing groove (28), the seam-lifting line-containing groove (27) is connected between the seam-lifting line-hooking groove (21) and the seam-lifting line-cutting edge (22), and the seam-rear line-containing groove (28) is connected between the line-distributing groove (23) and the seam-rear line-cutting edge (24).

7. The bird nest preventing movable knife according to claim 1, wherein: the movable cutter body (20) is provided with a trimming and branching tip (29) at the first needle falling side (25), and the trimming and branching tip (29) is triangular.

8. The utility model provides a sewing machine thread cutting mechanism, includes play seam cutter (40) and cutter (50) after the seam, its characterized in that: further comprising a bird nest preventing movable blade as claimed in any one of claims 1 to 7, the bird nest preventing movable blade being capable of reciprocating between a starting stitch cutter (40) and a post stitch cutter (50), the starting stitch cutting edge (22) being capable of engaging with the starting stitch cutter (40), and the post stitch cutting edge (24) being capable of engaging with the post stitch cutter (50).

9. The sewing machine thread cutting mechanism of claim 8, wherein: the seam lifting cutter (40) and the seam rear cutter (50) are fixed cutters which are fixedly arranged, and the seam lifting cutter (40) and the seam rear cutter (50) are respectively distributed on two sides of the machine needle (10).

10. The sewing machine thread cutting mechanism of claim 9, wherein: still including fixed aspiration channel (60) that set up, aspiration channel (60) and play seam cutter (40) distribute in the same side of needle (10), aspiration channel (60) have aim at inlet scoop (61) on movable cutter body (20) surface, play seam cutter (40), inlet scoop (61) and prevent bird's nest movable cutter follow radial outside of rotating shuttle (110) in the sewing machine and set gradually.

11. The sewing machine thread cutting mechanism of claim 9, wherein: the sewing machine also comprises a thread pressing plate (70) which is fixedly arranged, wherein the thread pressing plate (70) and the seam starting cutter (40) are distributed on the same side of the needle (10), and the thread pressing plate (70), the seam starting cutter (40) and the bird nest preventing movable cutter are sequentially arranged from outside to inside along the radial direction of a rotating shuttle (110) in the sewing machine; the wire pressing plate (70) is provided with first wire pressing parts (71) distributed on the outer end side of the slotting cutter (40), and the movable cutter body (20) is provided with second wire pressing parts (210);

When the seam starting and trimming blade (22) is adjacent to the seam starting cutter (40) and is not meshed, the second thread pressing part (210) is abutted with the first thread pressing part (71) and forms a thread clamping seam for clamping the upper thread.

12. The sewing machine thread trimming mechanism of claim 11, wherein: the line pressing plate (70) and the slotting cutter (40) are provided with tooth avoiding grooves (80).

13. The sewing machine thread cutting mechanism of claim 9, wherein: a second line pressing part (210) is arranged on the movable cutter body (20), and a third line pressing part is arranged on the starting cutter (40);

When the seam starting and trimming blade (22) is adjacent to the seam starting cutter (40) and is not meshed, the second thread pressing part (210) is abutted with the first thread pressing part (71) and forms a thread clamping seam for clamping the upper thread.

14. The sewing machine thread cutting mechanism of claim 9, wherein: the movable cutter body (20) is provided with a first cutter lifting part (211) and a second cutter lifting part (212), the first cutter lifting part (211) acts on the seam lifting cutter (40), and the second cutter lifting part (212) acts on the seam rear cutter (50).