阅读说明：本技术 一种刺绣机剪线装置、刺绣机剪线方法 (Thread cutting device and thread cutting method of embroidery machine ) 是由 陈天龙 方狄永 陈斌 于 2021-03-10 设计创作，主要内容包括：一种刺绣机剪线装置、刺绣机剪线方法,属于绣花机技术领域。装置包括均设于梭床上的动刀、定刀、动刀驱动机构；动刀安装在动刀驱动机构的刀杆上；动刀上设有位于临界轨迹上的动刀刀刃,或者,动刀上设有位于临界轨迹内且靠近临界轨迹边缘的动刀刀刃；临界轨迹是由刀杆轴心为圆心以及圆心至针板孔距离为半径构建的轨迹；动刀驱动机构驱动动刀向着定刀运动,运动时动刀的动刀剪线端头叉出待剪底线和面线并向着定刀继续运动,直到动刀与定刀重合时,动刀刀刃与定刀刀刃共同作用剪断底线和面线,所述动刀刀刃与所述定刀刀刃的相交点靠近针板孔。方法基于上述装置实现。本发明对现有剪线装置改动小,剪断后留在面料反面的底面线线头短,大大提高了绣品品质。(A thread trimming device and a thread trimming method of an embroidery machine belong to the technical field of embroidery machines. The device comprises a movable knife, a fixed knife and a movable knife driving mechanism which are all arranged on the shuttle bed; the movable knife is arranged on a knife bar of the movable knife driving mechanism; the moving knife is provided with a moving knife edge positioned on the critical track, or the moving knife is provided with a moving knife edge positioned in the critical track and close to the edge of the critical track; the critical track is a track constructed by taking the axis of the cutter bar as the circle center and taking the distance from the circle center to the hole of the needle plate as the radius; the movable knife driving mechanism drives the movable knife to move towards the fixed knife, the end of the movable knife cutting line of the movable knife moves to fork a bottom line and a facial line to be cut and continues to move towards the fixed knife until the movable knife and the fixed knife are overlapped, the bottom line and the facial line are cut off under the combined action of the movable knife edge and the fixed knife edge, and the intersection point of the movable knife edge and the fixed knife edge is close to the needle plate hole. The method is realized based on the device. The invention has small change to the existing thread cutting device, and the thread end of the bottom surface left on the reverse side of the fabric after cutting is short, thereby greatly improving the quality of embroidery.)

1. A thread cutting device of an embroidery machine comprises a movable cutter, a fixed cutter and a movable cutter driving mechanism which are all arranged on a shuttle race; the movable knife is arranged on a knife bar of the movable knife driving mechanism; the movable knife is characterized in that a movable knife blade positioned on the critical track is arranged on the movable knife, or the movable knife blade positioned in the critical track and close to the edge of the critical track is arranged on the movable knife; the critical track is a track constructed by taking the axis of the cutter bar as the circle center and taking the distance from the circle center to the hole of the needle plate as the radius; the movable knife driving mechanism drives the movable knife to move towards the fixed knife, the end of the movable knife cutting line of the movable knife moves to fork a bottom line and a facial line to be cut and continues to move towards the fixed knife until the movable knife is overlapped with the fixed knife, the movable knife edge and the fixed knife edge act together to cut the bottom line and the facial line, and the intersection point of the movable knife edge and the fixed knife edge is close to the needle plate hole.

2. The thread trimmer according to claim 1, wherein the stationary blade is positioned adjacent the edge of the throat plate opening at a position adjacent the movable blade such that the cutting edge of the stationary blade is adjacent the throat plate opening.

3. The thread trimmer according to claim 1, wherein the distance between the end of the stationary blade adjacent to the movable blade and the edge of the hole of the needle plate is set according to the length of the thread end of the bobbin thread left on the reverse side of the fabric after trimming.

4. The thread trimming device of claim 1, wherein the intersection point of the cutting edge of the movable knife and the cutting edge of the fixed knife is not more than 3.5mm away from the center of the needle plate hole.

5. The thread trimming device of claim 1, wherein the movable blade has an inclined surface that is inclined downward toward the movable blade thread trimming end of the stationary blade, the inclined surface is provided with a groove, the front end of the movable blade thread trimming end is provided with a notch for forming the movable blade thread trimming end, the groove is provided with a concave hole or a through hole at the bottom of the end of the other side of the groove away from the movable blade thread trimming end, the wall of the concave hole and the inclined surface form a movable blade edge, or the wall of the through hole and the inclined surface form a movable blade edge; and the bottom of the fixed knife, facing the fixed knife shearing end of the movable knife, is provided with a fixed knife blade.

6. An embroidery machine thread cutting device according to claim 5, wherein the recess or the through hole is located on a critical trajectory.

7. An embroidery machine thread trimming device according to claim 6, wherein the position of the notch closest to the recess or through hole is located on a critical trajectory of the recess or through hole.

8. The trimming device of claim 5, wherein the trimming end of the outermost movable blade is located at a position beyond the needle plate hole.

9. A thread cutting method of an embroidery machine, which is realized based on the thread cutting device of the embroidery machine as claimed in claim 1, and is applied to a control end of the embroidery machine, characterized in that the method comprises the following steps: after the movable knife is controlled to be opened, the machine needle is controlled to be inserted, and stitch embroidery is finished; when the thread cutting action is executed and a thread loop is formed, the movable knife is controlled to move towards the fixed knife, the movable knife forks out a bottom thread and an upper thread to be cut and continues to move towards the fixed knife until the movable knife is overlapped with the fixed knife, and the bottom thread and the upper thread are cut off; and after the thread trimming is finished and before the next needle is pulled up, the movable cutter is controlled to be opened.

10. A thread cutting method of an embroidery machine, which is realized based on the thread cutting device of the embroidery machine as claimed in claim 1, and is applied to a control end of the embroidery machine, characterized in that the method comprises the following steps: when the thread cutting action is executed and before a thread loop is formed, the movable knife is controlled to be opened; after the thread loop is formed, the movable knife is controlled to move towards the fixed knife, the movable knife forks out the bottom thread and the upper thread to be cut and continues to move towards the fixed knife until the movable knife is overlapped with the fixed knife, and the bottom thread and the upper thread are cut.

Technical Field

The invention belongs to the technical field of embroidery machines, and particularly relates to a thread cutting device and a thread cutting method of an embroidery machine.

Background

At present, in the industry of embroidery machines, when an embroidery finishes one graphic unit and begins to embroider another graphic unit, the upper thread and the bottom thread below a cloth cover need to be subjected to thread cutting treatment. The existing embroidery machine structure comprises an embroidery machine head, a thread buckling device and a thread cutting device, wherein the thread cutting device is used for cutting threads. Specifically, an upper thread driven by a needle of the embroidery machine penetrates through a cloth cover and is hooked by a rotating shuttle and is divided into a front part and a rear part, the front part and the rear part of the upper thread form a coil, a bottom thread in the rotating shuttle is wrapped by the rotating shuttle, after knotting is completed, a part of the upper thread and the bottom thread are cut off by scissors, and a thread head formed by the cut-off upper thread and the bottom thread is positioned below the upper thread.

The existing thread trimming device of the embroidery machine comprises a movable cutter, a fixed cutter and a movable cutter driving mechanism. The common thread cutting devices without adopting a thread separating structure generally include the following devices: A. the upper thread is fixed by the thread-fastening device into a triangle-like coil, and the bottom thread is positioned in the middle of the triangle-like coil, and the coil can be divided into a left waist line segment, a right waist line segment and a bottom line segment. The upper thread can be divided into a part to be cut (namely a left waist line segment) which can be hooked by the thread cutter and can be hooked by the thread hooking cutter and sent to the thread clamp part (namely a right waist line segment) by the thread buckling device. Firstly, the upper thread and the bottom thread of the left waist line segment are hooked after penetrating from the middle of the upper thread and the bottom thread of the right waist line segment. B. The bottom thread is hooked out first, the upper thread is fixed into a triangle-like coil by the thread-buckling device, and then the upper thread of the left waist line segment is hooked. The movable cutter and the fixed cutter are separated from the needle plate hole by a certain distance. Therefore, the cutting edge point when the movable cutter is tangent to the fixed cutter deviates from the hole of the needle plate by a certain distance, which causes overlong thread ends on the bottom surface of the reverse side of the fabric after being cut off and influences the quality of the embroidery. If the movable knife and the fixed knife move towards the direction close to the needle plate hole in order to shorten the thread end, the problem of interference exists, namely the movable knife interferes with a thread loop formed by the motion track of the fixed knife and the upper thread, the thread loop is hooked behind the movable knife in the opening process of the movable knife, the movable knife cannot hook the upper thread, or the upper thread is hooked and broken due to interference. Therefore, the existing thread cutting device can only arrange the movable cutter and the fixed cutter at a longer distance from the hole of the needle plate. If only the fixed blade position is considered to be moved without changing the movable blade position, only the fixed blade is moved in the needle plate hole direction. The movable knife is driven by the knife bar to rotate, the swing track of the cutting edge of the movable knife is not changed, and the cutting edge point when the movable knife is intersected with the fixed knife is still on the swing track of the cutting edge of the movable knife, so that the thread end cannot be shortened.

The applicant's prior invention patent application CN201610611193.3 discloses a high-precision thread cutting method of an embroidery machine, and specifically discloses a method comprising the following steps: the needle of the embroidery machine drives an upper thread to penetrate through a cloth cover on the needle plate to form two strands of upper threads, the two strands of upper threads are separated through a shuttle point of the rotating shuttle and drive the upper threads to rotate to form a coil at a thread buckling hook, the upper threads on the right side of the thread buckling hook are pulled by the hook knife, the hook knife returns to a pause position to determine the lengths of the two strands of upper threads under the cloth cover, and then the thread cutting positions of the scissors relative to the upper threads and the bottom threads are determined, and the thread cutting length is accurately determined. Although the method can control the thread cutting length, the cutting edge points of the movable cutter and the fixed cutter are far away from the needle plate hole when the thread is cut, so that the thread end of the bottom surface left on the reverse side of the fabric after cutting is too long.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a thread cutting device of an embroidery machine and a thread cutting method of the embroidery machine, which have the advantages that the change of the existing thread cutting device is small, the cut thread end is short, and the quality of embroidery is greatly improved.

The invention is realized by the following technical scheme:

a thread cutting device of an embroidery machine comprises a movable cutter, a fixed cutter and a movable cutter driving mechanism which are all arranged on a shuttle race; the movable knife is arranged on a knife bar of the movable knife driving mechanism; the movable knife is provided with a movable knife blade positioned on the critical track, or the movable knife is provided with a movable knife blade positioned in the critical track and close to the edge of the critical track; the critical track is a track constructed by taking the axis of the cutter bar as the circle center and taking the distance from the circle center to the hole of the needle plate as the radius; the movable knife driving mechanism drives the movable knife to move towards the fixed knife, the end of the movable knife cutting line of the movable knife moves to fork a bottom line and a facial line to be cut and continues to move towards the fixed knife until the movable knife is overlapped with the fixed knife, the movable knife edge and the fixed knife edge act together to cut the bottom line and the facial line, and the intersection point of the movable knife edge and the fixed knife edge is close to the needle plate hole.

The thread cutting device of the embroidery machine is a thread cutting device without adopting a thread dividing structure, namely, the thread dividing structure is not arranged on the movable knife, and the thread dividing structure is not needed to push the upper thread on the rear side of the rotating shuttle to one side of the opening direction of the thread cutting knife in the thread cutting process. The thread trimming device of the embroidery machine provided by the invention is slightly modified on the existing thread trimming device, so that the problem of long thread end remained on the bottom surface of the reverse side of the fabric after trimming is solved while the movable thread trimming blade is ensured to smoothly pass through the thread loop. The bottom thread end left on the reverse side of the fabric after cutting refers to the bottom thread end and the upper thread end left on the reverse side of the fabric after cutting, which will be collectively referred to as "thread ends" hereinafter.

The improvement of the thread cutting device of the embroidery machine of the invention is not the improvement of simple space installation position and size. Fig. 1 is a plan view illustrating a conventional thread trimming apparatus of an embroidery machine installed on the embroidery machine. If the movable knife and the fixed knife of the existing thread trimming device are shifted in the direction close to the needle plate hole and are arranged at the position close to the needle plate hole, the interference problem exists, and the movable knife cannot smoothly penetrate through the thread ring to capture the thread to be trimmed and the bottom thread. And the profile of the shifted movable knife greatly exceeds the needle plate hole, so that when the thread is cut, the upper thread is pushed to the rear of the rotating shuttle when the movable knife is opened, and the upper thread cannot be hooked smoothly. If the fixed knife of the existing thread trimming device is moved close to the direction of the needle plate hole and is arranged at a position close to the needle plate hole, the substantial problem of the length of the thread end is not solved. The movable knife is driven by the knife bar to rotate, the swing track of the cutting edge of the movable knife is not changed, and the cutting edge point when the movable knife and the fixed knife are intersected is still on the swing track of the cutting edge of the movable knife, so that the thread end of the bottom thread left on the back surface of the fabric after being cut cannot be shortened. Accordingly, it is not possible to solve the problem of the long thread end by simply adjusting the spatial installation position of the thread cutting device of the conventional embroidery machine, and various difficulties are involved in adjusting the spatial installation position.

In order to overcome the problems of interference, noodle thread hooking failure and the like and solve the problem of long thread head, the intersection point of the movable cutter and the fixed cutter for cutting off the bottom noodle is arranged as close to the needle plate hole as possible. Because the movable knife is rotated along the circumferential direction by the swinging of the knife bar, the position of the intersection point of the cutting edge of the movable knife and the cutting edge of the fixed knife is limited to be better as being closer to the critical track, and is preferably on the critical track. For this purpose, the following embodiments are available: 1. the fixed knife is not changed, only the movable knife is changed, and the arrangement position of the knife edge of the movable knife is mainly changed; 2. the fixed knife edge is arranged close to the needle plate hole, the movable knife is changed, and the arrangement position of the movable knife edge is mainly changed. The arrangement position of the moving knife edge is improved along a critical track, namely, the moving knife edge positioned on the critical track is arranged on the moving knife, or the moving knife edge positioned in the critical track and close to the edge of the critical track is arranged on the moving knife. The near critical path edge refers to a position very close to the critical path, and is generally not more than 2mm away from the critical path, and a distance within a tolerance range of +/-0.5 mm is also within the protection scope of the present invention. Because the movable knife of the thread cutting device can smoothly fork the bottom thread in the thread ring, the maximum outline size range of the movable knife is limited. When the intersection point of the movable knife and the fixed knife for cutting the bottom surface thread meets the condition of the critical track and the movable knife can smoothly fork the bottom surface thread, the general size of the movable knife is limited within the range. When comparing fig. 1 and fig. 2, the change of the size of the movable blade can be clearly known.

Preferably, one end of the fixed knife close to the movable knife is arranged close to the edge of the needle plate hole, so that the cutting edge of the fixed knife is close to the needle plate hole.

Preferably, the distance between one end of the fixed knife close to the movable knife and the edge of the needle plate hole is set according to the length of the bottom thread end left on the reverse side of the fabric after cutting.

Preferably, the distance between the intersection point of the movable knife edge and the fixed knife edge and the center of the needle plate hole is not more than 3.5 mm.

Preferably, the movable blade has an inclined surface inclined downwards towards the movable blade shearing end of the fixed blade, the inclined surface is provided with a groove, the front end of the movable blade shearing end is provided with a notch for forming the movable blade shearing end, the groove is provided with a concave hole or a through hole at the bottom of the tail end of the other side of the groove far away from the movable blade shearing end, the hole wall of the concave hole and the inclined surface form a movable blade cutting edge, or the hole wall of the through hole and the inclined surface form a movable blade cutting edge; and the bottom of the fixed knife, facing the fixed knife shearing end of the movable knife, is provided with a fixed knife blade.

Preferably, the recess hole or the through hole is located on the critical track.

Preferably, the position of the notch closest to the concave hole or the through hole is located on the critical track of the concave hole or the through hole.

Preferably, the position of the cutting line end of the movable knife at the outermost side of the movable knife exceeds the position of the pin hole.

Preferably, the edge profile of the movable blade is configured to push the bobbin thread to the outside of the rotary hook when the movable blade is opened.

A thread cutting method of an embroidery machine is realized based on the thread cutting device of the embroidery machine, and the method is applied to a control end of the embroidery machine and comprises the following steps: after the movable knife is controlled to be opened, the machine needle is controlled to be inserted, and stitch embroidery is finished; when the thread cutting action is executed and a thread loop is formed, the movable knife is controlled to move towards the fixed knife, the movable knife forks out a bottom thread and an upper thread to be cut and continues to move towards the fixed knife until the movable knife is overlapped with the fixed knife, and the bottom thread and the upper thread are cut off; and after the thread trimming is finished and before the next needle is pulled up, the movable cutter is controlled to be opened.

The thread trimming process of the thread trimming method of the invention is completely different from the existing thread trimming process. The wire cutting process of the wire cutting method is higher in reliability. Because there is a small probability that the following events occur in the existing thread cutting process: the upper thread can be pushed away when the movable knife is opened, and the upper thread can not return, so that the movable knife can not smoothly hook the upper thread. When the thread cutting method is adopted, the movable cutter is opened before the lower needle, and stitch embroidery can be performed, namely the problem that the upper thread is not clamped and does not return is solved, the small-probability event is avoided, and the operation reliability is better.

A thread cutting method of an embroidery machine is realized based on the thread cutting device of the embroidery machine, and the method is applied to a control end of the embroidery machine and comprises the following steps: when the thread cutting action is executed and before a thread loop is formed, the movable knife is controlled to be opened; after the thread loop is formed, the movable knife is controlled to move towards the fixed knife, the movable knife forks out the bottom thread and the upper thread to be cut and continues to move towards the fixed knife until the movable knife is overlapped with the fixed knife, and the bottom thread and the upper thread are cut.

The thread cutting process of the thread cutting method is the thread cutting process of the thread cutting device of the existing embroidery machine. The invention can realize thread trimming based on the improved thread trimming device of the embroidery machine without changing the execution time sequence of the control end of the embroidery machine. The method has wide applicability and is easy to realize.

The invention has the following beneficial effects:

a thread trimming device and method for an embroidery machine solve the problem that thread ends of a bottom surface of a fabric left after being trimmed by an existing thread trimming device are long on the basis of small improvement of the existing thread trimming device of the embroidery machine. The invention does not need to redesign a new thread cutting structure of the embroidery machine, does not need to manufacture the embroidery machine matched with the thread cutting device again, can improve the thread cutting effect of the embroidery machine without consuming a large amount of cost, and greatly improves the quality of embroidery products.

Drawings

FIG. 1 is a schematic view illustrating a thread trimming apparatus of a conventional embroidery machine; the track shown by the inner circle in the drawing is a track constructed by taking the axis of the cutter bar as the circle center and taking the distance from the circle center to the concave hole or the through hole 24 as the radius, and the track shown by the outer circle in the drawing is a track constructed by taking the axis of the cutter bar as the circle center and taking the distance from the circle center to the outer edge of the movable cutter as the radius;

FIG. 2 is a schematic structural diagram of a thread trimming device of an embroidery machine according to the present invention; the track shown by the inner circle in the drawing is a G track constructed by taking the axis of the cutter bar as the circle center and the distance from the circle center to the needle plate hole 4 as the radius, and the track shown by the outer circle in the drawing is a track constructed by taking the axis of the cutter bar as the circle center and the distance from the circle center to the outer edge of the movable cutter as the radius;

FIG. 3 is a schematic structural view of a movable knife in the thread trimming device of the embroidery machine according to the present invention;

FIG. 4 is a schematic structural view of a stationary knife in the thread trimming apparatus of the embroidery machine according to the present invention;

the dimensions shown in fig. 1 and 2 are only for illustrative purposes, and the present invention is not limited to the above dimensions, and mainly used to compare the difference between the thread trimming apparatus of the present invention and the existing thread trimming apparatus, and it is obvious that the distance between the inner circle trajectory and the outer circle trajectory is significantly shortened after the thread trimming apparatus is modified.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

Referring to fig. 2, the thread trimming device of the embroidery machine of the invention comprises a movable knife 2, a fixed knife 3 and a movable knife driving mechanism which are all arranged on a shuttle race 1. The movable knife 2 is arranged on a knife bar of the movable knife driving mechanism. The moving knife 2 is provided with a moving knife edge positioned on the critical track G; or the moving blade 2 is provided with a moving blade edge which is positioned in the critical track G and is close to the edge of the critical track. The critical track is a track constructed by taking the axis of the cutter bar as the circle center and taking the distance from the circle center to the needle plate hole 4 as the radius. The movable knife driving mechanism drives the movable knife 2 to move towards the fixed knife 3, the movable knife end of the movable knife 2 moves to fork a bottom line and a facial line to be cut and continues to move towards the fixed knife until the movable knife overlaps the fixed knife, the movable knife edge and the fixed knife edge act together to cut the bottom line and the facial line, and the intersection point of the movable knife edge and the fixed knife edge is close to the needle plate hole 4.

In one embodiment, the fixed knife is an existing fixed knife, i.e. the installation position and the structure of the fixed knife are not changed (see fig. 1); the movable knife is designed according to the invention. The improvement of the movable knife mainly lies in changing the position of the knife edge of the movable knife. In fig. 1, the installation point of the fixed knife 3 installed on the shuttle race 1 is on the same straight line with the axis of the knife bar. Designing a moving knife edge which is positioned in the critical track G and is close to the edge of the critical track on the moving knife; alternatively, a moving blade edge located on the critical path G is designed on the moving blade (see fig. 2). In this embodiment, the mounting position of the movable blade is not changed, i.e., the blade bar of the movable blade driving mechanism is not changed in position. The invention can also change the installation position of the movable knife, but the position of the knife bar is changed at the same time, the distance between the knife bar and the pin plate hole is changed, the critical track G is changed accordingly, and the arrangement position of the blade of the movable knife changes along with the change of the critical track G. Obviously, the implementation mode under the condition of not changing the installation position of the movable knife has the advantages of minimum modification and low cost and can be quickly put into application.

In another embodiment, the fixed cutter adopts the existing fixed cutter structure, but the installation position of the fixed cutter is changed (see fig. 2), and the installation position is deviated towards the direction of the needle plate hole; the movable knife is designed according to the invention. The mounting point of the fixed cutter 3 mounted on the shuttle race 1 is not in a straight line with the axis of the cutter bar, and the mounting point of the fixed cutter is arranged on the shuttle race 1 close to the needle plate hole 4. Specifically, one end of the fixed knife, which is close to the movable knife, is arranged close to the edge of the needle plate hole, so that the cutting edge of the fixed knife is close to the needle plate hole. The distance between one end of the fixed knife close to the movable knife and the edge of the needle plate hole is set according to the length of a bottom thread end left on the reverse side of the fabric after cutting. Specifically, the distance between the intersection point of the fixed knife edge and the movable knife edge and the needle plate hole is equal to the length of the thread end of the bottom surface thread left on the back surface of the fabric after cutting. Based on the structure, the distance between one end of the fixed cutter close to the movable cutter and the edge of the needle plate hole is adjusted adaptively according to the length of the thread end, so that the cutting edge of the fixed cutter is correspondingly arranged close to the needle plate hole. The improvement of the movable knife mainly lies in changing the position of the knife edge of the movable knife. Designing a moving knife edge which is positioned in the critical track G and is close to the edge of the critical track on the moving knife; alternatively, a moving blade edge located on the critical path G is designed on the moving blade (see fig. 2). In this embodiment, the mounting position of the movable blade is not changed, i.e., the blade bar of the movable blade driving mechanism is not changed in position. The invention can also change the installation position of the movable knife, but the position of the knife bar is changed at the same time, the distance between the knife bar and the pin plate hole is changed, the critical track G is changed accordingly, and the arrangement position of the blade of the movable knife changes along with the change of the critical track G. Obviously, the implementation mode under the condition of not changing the installation position of the movable knife has the advantages of minimum modification and low cost and can be quickly put into application.

In another embodiment, the fixed knife 3 has an extended design at one end of the fixed knife edge, the designed fixed knife edge is close to the pin plate hole, and the fixed knife mounting position is unchanged (see fig. 1); the channel adopts a moving blade 2 designed according to the invention. In fig. 1, the installation point of the fixed knife 3 installed on the shuttle race 1 is on the same straight line with the axis of the knife bar. Specifically, one end of the fixed knife, which is close to the movable knife, extends close to the edge of the needle plate hole, so that the cutting edge of the fixed knife is close to the needle plate hole. The distance between one end of the fixed knife close to the movable knife and the edge of the needle plate hole is set according to the length of a bottom thread end left on the reverse side of the fabric after cutting. Specifically, the distance between the intersection point of the fixed knife edge and the movable knife edge and the needle plate hole is equal to the length of the thread end of the bottom surface thread left on the back surface of the fabric after cutting. Based on the structure, the distance between one end of the fixed cutter close to the movable cutter and the edge of the needle plate hole is adjusted adaptively according to the length of the thread end, so that the cutting edge of the fixed cutter is correspondingly arranged close to the needle plate hole.

In the three embodiments, the distance between the intersection point of the cutting edge of the movable cutter and the cutting edge of the fixed cutter and the center of the pin plate hole is not more than 3.5mm, and the distance within the error range of +/-0.5 mm is also within the protection range of the invention. In order to avoid the interference of the needle plate holes, the thread ends cannot be too short, and the intersection point of the movable knife edge and the fixed knife edge cannot be positioned at the needle plate holes.

Fig. 3 shows a specific moving blade structure. The movable blade 2 has a downward inclined surface 22 facing the movable blade cutting end of the fixed blade 3, and the inclined surface 22 is provided with a groove 221. Therefore, when the movable cutter moves towards the fixed cutter, the bottom thread and the upper thread to be cut are gathered in the groove, and the groove leaves a space for embroidery thread, so that the embroidery thread has an extension space in the groove and cannot be tightened, and the embroidery thread is prevented from cutting sections in advance after the movable cutter is contacted with the fixed cutter; in addition, the inclined surface can prevent the cutting edge of the fixed knife from pushing the embroidery thread to directly rub and break. In order to control the lengths of the cut bottom thread and the upper thread to be consistent, the length should not be too long, and should not be too short, the embroidery thread needs to be cut when the cutting edge of the fixed knife is intersected with the cutting edge of the movable knife, but not to be cut in advance when the cutting edge of the movable knife moves towards the cutting edge of the fixed knife (namely, when the cutting edge of the movable knife is not intersected), and the structural design is needed.

The front end of the movable blade trimming end 21 is provided with a notch 23 for forming the movable blade trimming end 21. The notch can be a U-shaped notch or a V-shaped notch or a circular arc notch. The front end of the movable blade thread cutting end is divided into two movable blade thread cutting ends by the notch 23, so that one movable blade thread cutting end is used for forking the bottom thread, and the other movable blade thread cutting end is used for forking the upper thread (left waist line segment). The position of the movable blade thread trimming end 21 on the outermost side of the movable blade exceeds the position of the needle plate hole 4 (as can be seen in the figure, the movable blade thread trimming end is arranged towards the right relative to the needle plate hole), and the position of the movable blade thread trimming end 21 on the inner side of the movable blade does not exceed the position of the needle plate hole 4. Therefore, the movable knife can smoothly fork the bottom thread by using the movable knife thread cutting end on the outermost side, and fork the upper thread by using the movable knife thread cutting end on the innermost side. The invention does not allow the thread trimming ends of the two moving cutters to exceed the hole position of the needle plate, so that the moving cutters cannot smoothly fork the bottom thread. In addition, the edge profile of the movable knife is set to be a shape capable of pushing the bottom line to the outer side of the rotating shuttle when the movable knife is opened. Therefore, the movable knife can be smoothly forked to the bottom noodle line.

The notch 23, which is located closest to the recess or the through hole, is located on the critical path of the recess or the through hole. When the notch is a V-shaped mouth, the position of the notch closest to the recessed hole or the through hole is the inflection point of the V-shaped mouth (i.e. the tip of the V). Thus, the thread to be cut can be guided to the movable blade opening.

The groove 221 is provided with a concave hole 24 or a through hole 24 at the bottom of the end of the other side of the groove, which is far away from the movable blade trimming end 21, the hole wall of the concave hole 24 and the inclined surface 22 form a movable blade edge, or the hole wall of the through hole and the inclined surface 22 form a movable blade edge. The bottom of the fixed knife 3 facing the fixed knife line shearing end 31 of the movable knife 2 is provided with a fixed knife blade 32. Preferably, the through hole or the concave hole is an inclined hole to promote the blade edge of the movable blade to be sharper. Based on the design, the concave hole or the through hole can be arranged on the critical track; or, the concave hole or the through hole is arranged in the critical track G and is close to the edge of the critical track.

Fig. 4 shows a specific stationary knife structure. The bottom of the fixed knife 3 facing the fixed knife shearing end of the movable knife 2 is provided with a fixed knife blade 32. And (3) welding the raw material of the fixed cutter blade to the bottom of the fixed cutter, and grinding to obtain the fixed cutter blade. In one embodiment, the front end of the fixed-blade line-cutting end is flush with the front end of the fixed-blade cutting edge 32. In another embodiment, the front end of the fixed-blade line cutting end has an extension portion extending toward the movable blade, so that the fixed-blade edge 32 is retracted into the extension portion. In the former embodiment, when the embroidery thread is stretched between the fixed knife edge and the cutting end of the fixed knife before the cutting edge of the movable knife intersects with the cutting edge of the fixed knife, the embroidery thread is cut off or the embroidery thread is cut. In the latter embodiment, due to the existence of the extension part, the extension part prevents the embroidery thread from contacting with the cutting edge of the fixed knife in advance, so that the embroidery thread is not tightened on the cutting edge of the fixed knife in advance to cut hair or cut the embroidery thread. Meanwhile, in the latter embodiment, it is also necessary to note that the extension portion is not too long, the too long extension portion will contact with the cutting edge of the moving knife first, and tension exists between the extension portion and the cutting edge of the moving knife in the process that the moving knife moves towards the fixed knife, so that the cutting edge of the moving knife cuts the embroidery thread in advance. The movable cutter driving mechanism drives the movable cutter to move towards the fixed cutter, the end head of the movable cutter shearing wire of the movable cutter forks a bottom wire and a facial line to be sheared and continues to move towards the fixed cutter during movement, and the movable cutter cutting edge and the fixed cutter cutting edge act together to shear the bottom wire and the facial line until the movable cutter is overlapped with the fixed cutter. In addition, the front end of the fixed cutter line shearing end can be a plane or a concave surface, so that embroidery threads can be conveniently gathered at the cutting edge when the front end of the fixed cutter line shearing end with the concave surface is adopted.

The moving knife driving mechanism adopts the existing moving knife driving mechanism and comprises a knife bar, a swing arm and a rotating shaft connecting rod. The cutter arbor is vertical to be located on shuttle bed 1, the lower extreme of cutter arbor is connected the pivot connecting rod, swing arm one end is connected to the upper end of cutter arbor, and the swing arm other end has the driving piece, and when the cutter arbor drove the swing arm swing, the driving piece drove the sword motion. The drive member may be a pin, ball, bearing, pin, or the like. The present invention will not be described in detail, and reference is made to the prior patent documents of the applicant.

The invention also provides a thread cutting method of the embroidery machine, which is realized based on the thread cutting device of the embroidery machine and is applied to the control end of the embroidery machine, and the method comprises the following steps: after the movable knife is controlled to be opened, the machine needle is controlled to be inserted, and stitch embroidery is finished; when the thread cutting action is executed and after a thread loop is formed, the movable knife is controlled to move towards the fixed knife, the movable knife forks out a bottom thread and an upper thread to be cut and continues to move towards the fixed knife until the movable knife is overlapped with the fixed knife, and the bottom thread and the upper thread are cut off; and after the thread trimming is finished and before the next needle is pulled up, the movable cutter is controlled to be opened. Specifically, the movable knife is opened before the machine needle is put down, and stitch embroidery is executed; the method comprises the steps that a needle before thread cutting is carried out brings facial threads to the lower portion of the fabric (namely the back side of the fabric), when the thread cutting is required, a rotating shuttle catches the facial threads, a thread buckling device (such as a thread buckling fork) catches the facial threads to form a thread loop, then the movable cutter is controlled to move towards the fixed cutter, the bottom threads and the facial threads to be cut are forked, and when the cutting edge of the movable cutter is intersected with the cutting edge of the fixed cutter, the bottom threads and the facial threads are cut. The wire loop is a triangle-like wire loop described in the background art and is composed of an upper thread. The bottom wire is positioned in the middle of the triangular wire loop.

The invention also provides a thread cutting method of the embroidery machine, which is realized based on the thread cutting device of the embroidery machine and is applied to the control end of the embroidery machine, and the method comprises the following steps: before the wire loop is formed, the movable knife is controlled to be opened; after the thread loop is formed, the movable knife is controlled to move towards the fixed knife, the movable knife forks out the bottom thread and the upper thread to be cut and continues to move towards the fixed knife until the movable knife is overlapped with the fixed knife, and the bottom thread and the upper thread are cut. Specifically, a needle before the thread cutting action is carried out brings the upper thread to the lower part of the fabric (namely the back side of the fabric), the movable knife is controlled to be opened firstly, then the rotating shuttle catches the upper thread, and the thread buckling device (such as a thread buckling fork) catches the upper thread to form a thread loop; and then, controlling the movable cutter to move towards the fixed cutter, forking the bottom thread and the upper thread of the thread to be cut, and cutting the bottom thread and the upper thread when the cutting edge of the movable cutter is intersected with the cutting edge of the fixed cutter. The wire loop is a triangle-like wire loop described in the background art and is composed of an upper thread. The bottom wire is positioned in the middle of the triangular wire loop.

Both of the above-mentioned thread cutting methods are applicable to the thread cutting device of the embroidery machine of the present invention. The latter embodiment can directly put the improved thread cutting device of the embroidery machine into application without changing the embroidery operation time sequence of the existing embroidery machine; although the former embodiment needs to change the embroidering operation time sequence of the embroidering machine, the reliability of the thread cutting operation of the embroidering machine can be greatly improved, and the occurrence of the failure event of the thread hooking can be avoided.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the present invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.