A thread cutting device for a small head pitch embroidery machine

Abstract

A thread cutting device for a small head pitch embroidery machine belongs to the technical field of embroidery machines. The device includes a moving knife, a fixed knife, and a moving knife driving mechanism; the moving knife and the fixed knife are both arranged at the bottom of the needle plate of the embroidery machine, the moving knife and the fixed knife are respectively arranged on both sides of the needle plate hole and on both sides of the positive and negative directions of the Y-axis of the embroidery machine, and the moving knife driving mechanism is arranged on the shuttle bed; the moving knife cutting end of the moving knife has an inclined surface that slopes downward, a groove is formed on the inclined surface, a notch for forming the moving knife cutting end head is formed at the front end of the moving knife cutting end, and a moving knife blade is formed on the other side of the groove away from the moving knife cutting end head; the bottom of the fixed knife cutting end of the fixed knife is provided with a fixed knife blade; the moving knife driving mechanism drives the moving knife to move linearly towards the fixed knife, and when moving, the moving knife cutting end head forks out the bottom thread and the surface thread to be cut and continues to move towards the fixed knife. When the moving knife coincides with the fixed knife, the moving knife blade and the fixed knife blade act together to cut the bottom thread and the surface thread. The thread cutting of the present invention is simple, the thread cutting reliability is high, and the disassembly, assembly and maintenance are convenient.

Description

Technical Field

[0001] The present invention belongs to the technical field of embroidery machines, and particularly relates to a thread cutting device for an embroidery machine with a small head pitch. Background Art

[0002] Currently, in the embroidery machine industry, when an embroidery product completes one graphic unit and starts embroidering another graphic unit, it is necessary to cut the upper thread and the bobbin thread below the fabric surface. The existing embroidery machine structure includes an embroidery machine head, a thread clamping device, and a thread cutting device, and the thread cutting device is used for cutting threads. Specifically, a single upper thread driven by the embroidery machine needle passes through the fabric surface and is hooked by the rotary hook and separated into front and rear strands. These front and rear strands form a loop that wraps the bobbin thread in the rotary hook. After knotting is completed, one strand of the upper thread and the bobbin thread are cut by scissors, and the cut strand of the upper thread and the bobbin thread form a thread end located below the fabric surface.

[0003] The existing thread trimming device of an embroidery machine includes a moving knife, a fixed knife, and a moving knife driving mechanism. The thread trimming device is divided into two categories: the thread trimming device with a thread separating structure and the thread trimming device without a thread separating structure. For the thread trimming device with a thread separating structure, generally, structures such as a thread picking hook and a thread separating hook are set on the moving knife. When the moving knife opens, thread separation is first performed. The surface thread behind the rotating hook is picked and pushed to one side in the direction where the thread trimming knife opens. At the same time, the surface thread is fixed as a triangular-like coil by using a thread clamping device. Finally, the bobbin thread and the left surface thread are picked and cut. In addition, there is also an independent thread separating structure set for the thread trimming device. This type of thread trimming device can be used for embroidery machines with a small stitch pitch. However, the thread trimming device needs to achieve thread trimming through the dynamic cooperation between mechanical parts, and the process is complex. It is necessary to separate the threads first, then pick them, and finally cut them. Moreover, the possibility of thread separation failure is very high. Especially when the surface thread tension is not large enough, it is very difficult for the two strands of surface thread to be smoothly separated. In addition, the bobbin thread after being cut by the existing thread trimming device is easily hung on the rotating hook. When the rotating hook rotates idly, the bobbin thread is easily wound around the rotating hook, affecting the surface thread knotting. The thread trimming devices without a thread separating structure generally include the following types: A. The thread clamping device has fixed the surface thread as a triangular-like coil, and the bobbin thread is located in the middle of the triangular-like coil. This coil can be divided into a left waist line segment, a right waist line segment, and a bottom side line segment. The thread clamping device can be used to divide the surface thread into a part that can be picked by the thread trimming knife and cut (i.e., the left waist line segment), and a part that can be picked by the hook knife and sent to the surface thread clamp (i.e., the right waist line segment). First, it penetrates from the middle of the surface thread and the bobbin thread of the right waist line segment, and then picks the surface thread and the bobbin thread of the left waist line segment. This type of thread trimming device generally realizes thread trimming by the moving knife making a circular motion towards the fixed knife. The moving knife and the fixed knife are often set on the rotating hook box and below the needle plate. The axis of the knife rod of the moving knife driving mechanism coincides with the center of the motion trajectory of the moving knife, and the moving knife shaft is set near the plane formed by the triangular thread loop for the most stable thread picking. Generally, this type of thread trimming device is suitable for embroidery machines with a large stitch pitch. For embroidery machines with a small stitch pitch, there is not enough space to use the above thread trimming device, and there will be space interference. B. The bobbin thread is first picked out, the thread clamping device fixes the surface thread as a triangular-like coil, and then the surface thread of the left waist line segment is picked. Although the thread trimming device of Scheme B can be used for embroidery machines with a small stitch pitch, this thread trimming process requires two thread picking actions and then thread trimming. The thread trimming process is relatively complex and depends on the dynamic cooperation between mechanical parts.

[0004] The utility model patent CN201071451Y discloses a thread cutting device for an embroidery machine, and specifically discloses that the device is arranged on the needle plate of the embroidery machine. The device is composed of a moving knife, a fixed knife, and a moving knife drive for controlling the movement of the moving knife. The moving knife and the fixed knife are arranged in a moving knife assembly which is also arranged on the needle plate. The moving knife can overlap with the fixed knife under the control of the moving knife drive mechanism. A thread catching device for pressing the bottom thread end during the process of the moving knife hooking the thread and cutting the thread is also arranged on the needle plate. When changing the needle or finishing sewing, the control system of the embroidery machine sends a signal to drive the thread changing connecting rod. The moving knife extends out of the sliding guide along the chute in the sliding guide under the drive of the thread changing connecting rod and moves towards the embroidery thread direction. The pointed head arranged at the end of the moving knife enables the embroidery thread to move along the two inclined sides of the pointed head, so that the embroidery thread smoothly falls into the reverse hook. At the same time, the control system sends a signal to drive the electromagnet, and the electromagnet drives the iron core to move. The crescent plate rotates around the torsion spring under the drive of the iron core hinged to it. The other end of the crescent plate drives the thread catcher to move through the fixed pin stuck in the groove, so that the thread catcher moves towards the needle hole plate 2 and presses the bottom thread. At this time, the relative distance between the two feet of the torsion spring is reduced, and the torsion spring stores the restoring elastic force. Then, under the action of the motor, the thread changing connecting rod makes the moving knife hook the embroidery thread and move towards the fixed knife direction. When the cutting surface of the moving knife contacts the cutting edge surface of the fixed knife, the embroidery thread is cut off. After the thread cutting is completed, the electromagnet stops being powered on. Under the action of the restoring elastic force of the torsion spring, the crescent plate and the electromagnet iron core both return to the original state, and the thread catching end of the thread catcher presses the bottom thread end and returns to the original position, waiting for the start of the next thread cutting. During the whole thread cutting process, the thread catcher always presses the bottom thread end, which is convenient for the start of the next sewing action. The moving knife and the fixed knife of this device are distributed on the same side of the needle plate. The moving knife needs to extend out to hook the thread and then return to move to the fixed knife side to cut the thread. The structure of the moving knife of this device is complex, and a thread catcher is required to cooperate to complete the thread cutting, and the thread cutting process is complex. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a thread cutting device for an embroidery machine, which is simple in thread cutting, high in thread cutting reliability, and convenient for disassembly, installation and maintenance.

[0006] The present invention is achieved by the following technical solutions:

[0007] A thread cutting device for a small head pitch embroidery machine, comprising a moving knife, a fixed knife, and a moving knife driving mechanism; the moving knife and the fixed knife are both arranged at the bottom of the needle plate of the embroidery machine, the moving knife and the fixed knife are respectively arranged on both sides of the needle plate hole and on both sides of the positive and negative directions of the Y-axis of the embroidery machine, and the moving knife driving mechanism is arranged on the shuttle bed; the moving knife cutting end of the moving knife facing the fixed knife has an inclined surface that slopes downward, a groove is formed on the inclined surface, a notch for forming the moving knife cutting end head is formed at the front end of the moving knife cutting end, and a moving knife blade is formed on the other side of the groove away from the moving knife cutting end head; the bottom of the fixed knife cutting end of the fixed knife facing the moving knife is provided with a fixed knife blade; the moving knife driving mechanism drives the moving knife to move towards the fixed knife, and when moving, the moving knife cutting end head of the moving knife forks out the bottom thread and the surface thread to be cut and continues to move towards the fixed knife. When the moving knife coincides with the fixed knife, the moving knife blade and the fixed knife blade act together to cut the bottom thread and the surface thread.

[0008] Generally, an embroidery machine includes multiple heads. Those skilled in the art often define the direction where the multiple heads are located as the X-axis direction of the embroidery machine, and the direction perpendicular to the X-axis direction is the Y-axis direction. The positive direction of the Y-axis is the same as the front direction of the machine needle (that is, the direction facing the machine operator), and the negative direction of the Y-axis is the same as the back direction of the machine needle (that is, in front of the machine operator). The positive direction of the X-axis is the right side direction of the machine operator, and the negative direction of the X-axis is the left side direction of the machine operator.

[0009] The moving knife and the fixed knife of the thread cutting device of the present invention are installed at the bottom of the needle plate of the embroidery machine. When the needle plate is removed, the moving knife and the fixed knife can be removed together, which is convenient for disassembly, installation and maintenance. The moving knife and the fixed knife of this thread cutting device are respectively arranged on both sides of the needle plate hole (for example, the moving knife is located in the negative direction of the Y-axis, and the fixed knife is located in the positive direction of the Y-axis; or for example, the moving knife is located in the positive direction of the Y-axis, and the fixed knife is located in the negative direction of the Y-axis), eliminating the step that the moving knife needs to extend first to hook the thread to be cut when the moving knife and the fixed knife are on the same side. In the process of the moving knife of the present invention moving towards the fixed knife, after forking out the thread to be cut, it is sent to the fixed knife. When the fixed knife coincides with the moving knife, their respective blades intersect to complete the thread cutting process. The present invention is mainly completed by the intersection of the moving knife blade and the fixed knife blade located on both sides of the needle plate hole. The structure where the moving knife or the fixed knife extends to the opposite side is also within the protection scope of this patent. The positive and negative directions of the Y-axis of the embroidery machine defined by the present invention cover the area of the positive direction of the Y-axis and the area of the negative direction of the Y-axis, that is, the linear movement trajectory of the moving knife towards the fixed knife is not limited to being parallel to the Y-axis (including cases where it coincides with or is parallel to the Y-axis axis where the center of the needle plate hole is located), and can also intersect.

[0010] Refer to Figure 1 , Figure 1Three cases a, b, and c are shown (marked at the axis center of the tool bar of the moving knife driving mechanism). Case a is a schematic diagram of the thread cutting principle of the thread cutting device on the embroidery machine with a large head distance. The thread cutting device is located outside the outer diameter range of the rotary hook. Among them, the moving knife is installed on the tool bar of the moving knife driving mechanism, that is, the center of the moving trajectory of the moving knife coincides with the axis center of the tool bar. The dotted lines in the figure are the swinging trajectory of the tool bar and the moving trajectory of the moving knife. Case a corresponds to the A thread cutting device in the background technology. It can be seen from the figure that the best angle for threading through the upper thread and the bobbin thread at the right-side waist line segment should be as perpendicular as possible to the X-axis direction of the embroidery machine. For the embroidery machine with a small head distance, the above thread cutting device cannot work properly in a limited space, and there is mechanical space interference. Case b is a schematic diagram of the thread cutting principle of the thread cutting device on the embroidery machine with a small head distance. The thread cutting device is located within the outer diameter range of the rotary hook. Among them, the moving knife is installed on the tool bar of the moving knife driving mechanism, that is, the center of the moving trajectory of the moving knife coincides with the axis center of the tool bar. The dotted lines in the figure are the swinging trajectory of the tool bar and the moving trajectory of the moving knife. Case b corresponds to the thread cutting device with a thread separating structure and the B thread cutting device in the background technology. Although these two thread cutting devices can be applied to the embroidery machine with a small head distance, they both rely on the mechanical dynamic cooperation of the embroidery machine, and the thread separating scheme also has the problem of low reliability. Case c is a schematic diagram of the thread cutting principle of the thread cutting device of the present invention on the embroidery machine with a small head distance. The thread cutting device is located within the outer diameter range of the rotary hook. Among them, the moving knife is separated from the tool bar of the moving knife driving mechanism. The moving trajectory of the moving knife is a straight-line trajectory, and it can fork the upper and bobbin threads to be cut at the best angle. The tool bar has its own independent moving trajectory. The present invention can realize the forking and cutting of the upper and bobbin threads to be cut during the process of the moving knife moving towards the fixed knife, and the realization process is simple and highly reliable. The above principle analysis is described based on the moving knife driving mechanism in the form of a tool bar, but the thread cutting device of the present invention is not limited to the moving knife driving mechanism in the form of a tool bar.

[0011] In addition, compared with the existing thread cutting structure, the upper thread and the bobbin thread after cutting in the prior art are located inside the rotary hook and are easily wound into the rotary hook during the idle rotation of the rotary hook, while the upper thread and the bobbin thread after cutting by the thread cutting device of the present invention are located outside the rotary hook and do not interfere with the idle rotation of the rotary hook.

[0012] Preferably, the groove wall and the inclined surface at the other end of the groove away from the thread cutting end of the moving knife form the moving knife blade.

[0013] Preferably, a concave hole or a through hole is provided at the bottom of the groove at the other end of the groove away from the thread cutting end of the moving knife. The hole wall of the concave hole and the inclined surface form the moving knife blade, or the hole wall of the through hole and the inclined surface form the moving knife blade.

[0014] Preferably, the front end of the thread cutting end of the fixed knife has an extension portion extending towards the moving knife, so that the fixed knife blade is retracted into the extension portion.

[0015] Preferably, a sliding groove is provided on the moving knife; the swing arm of the moving knife driving mechanism slides in the sliding groove to drive the moving knife to move.

[0016] Preferably, the thread cutting device of the embroidery machine further includes a first base installed at the bottom of the needle plate of the embroidery machine; the first base is used to support the moving knife when the moving knife coincides with the fixed knife, so that the cutting edge of the moving knife can interact with the cutting edge of the fixed knife to cut the bobbin thread and the face thread.

[0017] Preferably, the first base is an elastic member; alternatively, an elastic member is provided in the first base, and the elastic member acts on the moving knife.

[0018] Preferably, the thread cutting device of the embroidery machine further includes a second base or a third base installed at the bottom of the needle plate of the embroidery machine, and the moving knife passes through the second base or the third base, and the moving knife driving mechanism drives the moving knife to move along the guiding direction of the second base or the third base; it also includes a second base or a third base installed on the shuttle bed, and the moving knife passes through the second base or the third base, and the moving knife driving mechanism drives the moving knife to move along the guiding direction of the second base or the third base.

[0019] Preferably, the thread cutting device of the embroidery machine further includes a second base and a third base installed at the bottom of the needle plate of the embroidery machine, and the moving knife passes through the second base and the third base, and the second base and the third base are used to guide the moving direction of the moving knife; alternatively, it further includes a second base or a third base installed at the bottom of the needle plate of the embroidery machine, and a third base or a second base installed on the shuttle bed, and the moving knife passes through the second base and the third base, and the second base and the third base are used to guide the moving direction of the moving knife; alternatively, it further includes a second base or a third base partially installed at the bottom of the needle plate of the embroidery machine and partially installed on the shuttle bed, and a third base or a second base installed at the bottom of the needle plate of the embroidery machine, and the moving knife passes through the second base and the third base, and the second base and the third base are used to guide the moving direction of the moving knife; alternatively, it further includes a second base or a third base partially installed at the bottom of the needle plate of the embroidery machine and partially installed on the shuttle bed, and a third base or a second base installed on the shuttle bed, and the moving knife passes through the second base and the third base, and the second base and the third base are used to guide the moving direction of the moving knife.

[0020] Preferably, the fixed knife is installed at the bottom of the needle plate of the embroidery machine through a fixing block; alternatively, the fixed knife is directly installed at the bottom of the needle plate of the embroidery machine or on the shuttle bed; alternatively, the fixed knife is installed on the shuttle bed through a bracket.

[0021] Preferably, the moving knife driving mechanism includes a knife rod, a swing arm, and a rotating shaft connecting rod; the knife rod is vertically arranged on the shuttle bed, the lower end of the knife rod is connected to the rotating shaft connecting rod, the upper end of the knife rod is connected to one end of the swing arm, and the other end of the swing arm is provided with a driving member. When the knife rod drives the swing arm to swing, the driving member drives the moving knife to move.

[0022] Preferably, the thread cutting device of the embroidery machine further includes a second base and a third base installed at the bottom of the needle plate of the embroidery machine. The second base is located at the front end in the swinging direction of the swing arm, and the third base is located at the rear end in the swinging direction of the swing arm. The moving knife passes through the second base and the third base; alternatively, it further includes a guide rail installed at the bottom of the needle plate. The guide rail is provided with a space allowing the swing arm to swing. The guide rail extends from the front end in the swinging direction of the swing arm to the rear end in the swinging direction of the swing arm, and the moving knife passes through the guide rail.

[0023] Preferably, the linear trajectory of the linear motion of the moving knife towards the fixed knife is parallel to the Y-axis axis of the embroidery machine where the needle plate hole is located, or the linear trajectory of the linear motion of the moving knife towards the fixed knife intersects with the Y-axis axis of the embroidery machine where the needle plate hole is located.

[0024] Preferably, the fixed knife is arranged at the bottom of the needle plate of the embroidery machine in front of the rotating shuttle of the embroidery machine; the moving knife is arranged at the bottom of the needle plate of the embroidery machine above the rotating shuttle of the embroidery machine.

[0025] Preferably, when the moving knife driving mechanism drives the moving knife to change from a linear motion towards the fixed knife to a circular motion, the axis of the knife rod does not coincide with the center of the circular motion trajectory of the moving knife.

[0026] In the circular arc scheme, the above preferred scheme is equally applicable.

[0027] The present invention has the following beneficial effects:

[0028] A thread cutting device for a small head distance embroidery machine, by utilizing the process of the moving knife moving towards the fixed knife, can complete the acquisition of the bottom thread and the top thread to be cut and the cutting of the bottom and top threads at one time, with high cutting efficiency, convenience, and high cutting reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the thread cutting principle of the existing thread cutting device of the embroidery machine and the thread cutting device of the present invention;

[0030] Figure 2 A three-dimensional structure schematic diagram of a thread cutting device for a small head distance embroidery machine (installed on an embroidery machine) of the present invention; among them, there is a head on the embroidery machine;

[0031] Figure 3 It is a side view of a thread cutting device for a small head distance embroidery machine (installed on an embroidery machine) of the present invention;

[0032] Figure 4This is a schematic structural diagram of the thread cutting device of the small head pitch embroidery machine of the present invention installed on the needle plate of the embroidery machine;

[0033] Figure 5 This is a three-dimensional structure diagram of the thread cutting device of the small head pitch embroidery machine of the present invention cooperating with the rotary hook;

[0034] Figure 6 This is a side view of the thread cutting device of the small head pitch embroidery machine of the present invention cooperating with the rotary hook;

[0035] Figure 7 This is a schematic structural diagram of the fixed knife in the thread cutting device of the small head pitch embroidery machine of the present invention;

[0036] Figure 8 This is a schematic structural diagram of the moving knife in the thread cutting device of the small head pitch embroidery machine of the present invention;

[0037] Figure 9 This is a schematic structural diagram of an implementation manner of the thread cutting device of the small head pitch embroidery machine of the present invention;

[0038] Figure 10 This is a schematic structural diagram of another implementation manner of the thread cutting device of the small head pitch embroidery machine of the present invention;

[0039] Figure 11 This is a schematic structural diagram of an implementation manner of the cooperation between the moving knife and the swing arm in the thread cutting device of the small head pitch embroidery machine of the present invention. Detailed implementation manners

[0040] The following are specific embodiments of the present invention and in combination with the accompanying drawings, the technical solutions of the present invention will be further described, but the present invention is not limited to these embodiments.

[0041] Such as Figure 2-6 , a thread cutting device for a small head pitch embroidery machine, including a moving knife 10, a fixed knife 20, and a moving knife driving mechanism. The moving knife 10 and the fixed knife 20 are both arranged at the bottom of the needle plate 1 of the embroidery machine. The moving knife 10 and the fixed knife 20 are respectively arranged on both sides of the needle plate hole and on both sides of the positive and negative directions of the Y-axis of the embroidery machine. The moving knife driving mechanism is arranged on the shuttle bed 2. In one implementation manner, the moving knife 10 can be arranged on the negative Y-axis side of the needle plate hole of the embroidery machine, and the fixed knife 20 can be arranged on the positive Y-axis side of the needle plate hole of the embroidery machine (such as Figure 3 , 9 , 10). That is, the fixed knife is arranged at the bottom of the needle plate of the embroidery machine in front of the rotary hook 7 of the embroidery machine, and the moving knife is arranged at the bottom of the needle plate of the embroidery machine above the rotary hook 7 of the embroidery machine. In another implementation manner, the moving knife 10 can be arranged on the positive Y-axis side of the needle plate hole of the embroidery machine, and the fixed knife 20 can be arranged on the negative Y-axis side of the needle plate hole of the embroidery machine. This text mainly takes the former implementation manner as an example for description, and the structure and installation method designed in the former implementation manner are also applicable to the latter implementation manner.

[0042] As Figure 2-8 , the moving blade 10 has an inclined surface 11 that slopes downward at its cutting end facing the fixed blade 20, and a groove 111 is formed on the inclined surface 11. In this way, when the moving blade moves towards the fixed blade, the bottom thread and the top thread to be cut will converge in this groove, and the groove leaves space for the embroidery thread. In this way, the embroidery thread has room to stretch in the groove and will not be taut, avoiding premature cutting of the embroidery thread after the moving blade contacts the fixed blade. In addition, the inclined surface is provided to prevent the cutting edge of the fixed blade from directly rubbing against the embroidery thread and causing it to break. In order to control the lengths of the cut bottom thread and top thread to be consistent, neither too long nor too short, it is necessary to ensure that the embroidery thread is cut when the cutting edge of the fixed blade intersects with the cutting edge of the moving blade, rather than being prematurely cut during the movement of the cutting edge of the moving blade towards the cutting edge of the fixed blade (i.e., before intersection). Therefore, the above structural design is necessary.

[0043] A notch 12 is formed at the front end of the cutting end of the moving blade for forming the cutting end of the moving blade. The notch can be a U-shaped notch, a V-shaped notch or an arc-shaped notch. The figure shows that the front end of the cutting end of the moving blade is divided into two cutting ends of the moving blade by using the notch 12. In this way, one cutting end of the moving blade is used to fork the bottom thread, and the other cutting end of the moving blade is used to fork the top thread (the left waist line segment). The present invention is not limited to the above two cutting ends of the moving blade, and notches in the form of waves or multiple U-shaped, V-shaped or arc-shaped notches can also be adopted, so as to generate three cutting ends of the moving blade. Two cutting ends of the moving blade are used to fork the bottom thread and the top thread (the left waist line segment), and one cutting end of the moving blade is used to separate the top thread (the right waist line segment) from the part to be cut.

[0044] On the other side of the groove 111 away from the moving knife thread-cutting end, a moving knife blade is formed. Specifically, the groove wall at the end of the other side of the groove 111 away from the moving knife thread-cutting end and the inclined surface 11 form the moving knife blade. In order to further improve the sharpness of the cutting edge, a concave hole 112 or a through hole 112 is provided at the bottom of the end of the other side of the groove 111 away from the moving knife thread-cutting end. The hole wall of the concave hole and the inclined surface form the moving knife blade, or the hole wall of the through hole and the inclined surface form the moving knife blade. Preferably, the through hole or the concave hole is an inclined hole to make the moving knife blade sharper. At the bottom of the fixed knife thread-cutting end facing the moving knife 10 of the fixed knife 20, a fixed knife blade is provided. The raw material of the fixed knife blade is welded to the bottom of the fixed knife and the fixed knife blade is obtained after grinding. In one embodiment, the front end of the fixed knife thread-cutting end is flush with the front end of the fixed knife blade 201. In another embodiment, the front end of the fixed knife thread-cutting end has an extension 202 extending towards the moving knife, so that the fixed knife blade 201 is retracted into the extension 202. In the former embodiment, before the moving knife blade intersects with the fixed knife blade, once the embroidery thread is tightened at the fixed knife thread-cutting end and the fixed knife blade, the embroidery thread will be cut off in advance or the embroidery thread will be trimmed. In the latter embodiment, due to the existence of the extension, the extension blocks the premature contact of the embroidery thread with the fixed knife blade, mainly preventing the embroidery thread from being prematurely tightened at the fixed knife blade and being trimmed or cut off. At the same time, it should also be noted in the latter embodiment that the extension should not be too long. If the extension is too long, it will contact the moving knife blade first. During the movement of the moving knife towards the fixed knife, there is tension between the extension and the moving knife blade, and finally the moving knife blade will cut off the embroidery thread in advance. The moving knife driving mechanism drives the moving knife to move towards the fixed knife. When moving, the moving knife thread-cutting end of the moving knife forks out the bottom thread and the surface thread to be cut and continues to move towards the fixed knife until the moving knife coincides with the fixed knife, and the moving knife blade and the fixed knife blade act together to cut off the bottom thread and the surface thread. In addition, the front end of the fixed knife thread-cutting end can be a plane or a concave surface. When the front end of the fixed knife thread-cutting end with a concave surface is adopted, it is convenient for the embroidery thread to converge at the cutting edge.

[0045] The stationary knife and the moving knife can cut the bobbin thread and the face thread, mainly relying on the tension between them when they intersect. In one embodiment, at least one of the stationary knife and the moving knife has a functional design with elastic deformation ability. When only the stationary knife has the functional design with elastic deformation ability, when the moving knife moves towards the stationary knife to the intersection position, the deformation of the stationary knife itself provides the tension for cutting the embroidery thread, enabling the thread cutting device to smoothly cut the embroidery thread. When only the moving knife has the functional design with elastic deformation ability, when the moving knife moves towards the stationary knife to the intersection position, the deformation of the moving knife itself provides the tension for cutting the embroidery thread, enabling the thread cutting device to smoothly cut the embroidery thread. Similarly, when both have the functional design with elastic deformation ability, both provide the tension required for cutting the embroidery thread when they intersect. In another embodiment, the thread cutting device of the embroidery machine of the present invention further includes a first base 3 installed at the bottom of the needle plate of the embroidery machine. The first base 3 is used to support the moving knife when the moving knife and the stationary knife coincide, so that the cutting edges of the moving knife and the stationary knife can interact to cut the bobbin thread and the face thread. The first base 3 is a base with a U-shaped structure or a base with a loop structure, and the first base is fixed to the bottom of the needle plate of the embroidery machine through fasteners (such as bolts). Among them, the first base is an elastic component; or, an elastic component is provided inside the first base, and the elastic component acts on the moving knife. Since the first base is used to support the moving knife, the first base with the ability of elastic deformation provides the tension for cutting the embroidery thread, enabling the thread cutting device to smoothly cut the embroidery thread. In another embodiment, at least one of the stationary knife and the moving knife can have a functional design with elastic deformation ability, and it is set as the first base that is an elastic component or the first base provided with an elastic component. That is, the combination of the above two embodiments.

[0046] The thread cutting device of the embroidery machine with a small head distance of the present invention is also provided with a structure for positioning and guiding the moving direction of the moving knife. In one embodiment, the thread cutting device of the embroidery machine of the present invention further includes a second base 4 or a third base 5 installed at the bottom 1 of the needle plate of the embroidery machine, and the moving knife passes through the second base 4 or the third base 5, and the swing arm of the moving knife driving mechanism drives the moving knife to move along the guiding direction of the second base 4 or the third base 5. The second base is arranged at the front end in the direction where the driving mechanism drives the moving knife towards the stationary knife; the third base is arranged at the rear end in the direction where the driving mechanism drives the moving knife towards the stationary knife. In this way, relying on the moving knife driving mechanism (when the moving knife driving mechanism includes a swing arm, then relying on the swing arm) and the combination of a certain base to achieve the guiding of the moving knife movement. In one embodiment, the thread cutting device of the embroidery machine of the present invention further includes a second base 4 or a third base 5 installed on the shuttle bed, and the moving knife passes through the second base 4 or the third base 5, and the swing arm of the moving knife driving mechanism drives the moving knife to move along the guiding direction of the second base 4 or the third base 5. In another embodiment (see Figure 4), the thread cutting device of the embroidery machine of the present invention further includes a second base 4 and a third base 5 installed at the bottom of the needle plate 1 of the embroidery machine, and the moving knife passes through the second base 4 and the third base 5, and the second base 4 and the third base 5 are used to guide the moving direction of the moving knife; or, the thread cutting device of the embroidery machine of the present invention further includes a second base 4 or a third base 5 installed at the bottom of the needle plate 1 of the embroidery machine, and a third base 5 or a second base 4 installed on the shuttle bed 2, and the moving knife 10 passes through the second base 4 and the third base 5, and the second base 4 and the third base 5 are used to guide the moving direction of the moving knife; or, the thread cutting device of the embroidery machine of the present invention further includes a second base 4 or a third base 5 partially installed at the bottom of the needle plate 1 of the embroidery machine and partially installed on the shuttle bed 2, and a third base 5 or a second base 4 installed at the bottom of the needle plate 1 of the embroidery machine, and the moving knife passes through the second base 4 and the third base 5, and the second base 4 and the third base 5 are used to guide the moving direction of the moving knife; or, the thread cutting device of the embroidery machine of the present invention further includes a second base 4 or a third base 5 partially installed at the bottom of the needle plate 1 of the embroidery machine and partially installed on the shuttle bed 2, and a third base 5 or a second base 4 installed on the shuttle bed 2, and the moving knife passes through the second base 4 and the third base 5, and the second base 4 and the third base 5 are used to guide the moving direction of the moving knife.

[0047] Both the first base 3 and the second base 4 adopt the same specification of the base, so that the level of the movement of the moving knife and the level when the moving knife intersects with the fixed knife are at the same height. Or, the first base 3, the second base 4 and the third base 5 all adopt the same specification of the base, so that the level of the movement of the moving knife and the level when the moving knife intersects with the fixed knife are at the same height. Or, the first base 3 and the third base 5 both adopt the same specification of the base, so that the level of the movement of the moving knife and the level when the moving knife intersects with the fixed knife are at the same height.

[0048] The above-mentioned moving knife guiding can be set in a straight line direction. In one embodiment (such as Figure 9 ), the moving knife is designed as a straight bar structure, the fixed knife and the moving knife are arranged on the same straight line, the straight line trajectory of the straight line movement of the moving knife towards the fixed knife is parallel to the Y-axis axis of the embroidery machine where the needle plate hole is located, that is, the fixed knife and the moving knife are linearly distributed along the Y-axis direction of the embroidery machine. At this time, both the second base 4 and the third base 5 are arranged in the length direction where the moving knife is located, and the thread cutting process of the moving knife moving linearly towards the fixed knife can be realized. In another embodiment, the moving knife is designed as a straight bar structure, the straight line trajectory of the straight line movement of the moving knife towards the fixed knife intersects with the Y-axis axis of the embroidery machine where the needle plate hole is located, that is, the moving knife is placed obliquely, and both the second base 4 and the third base are arranged in the length direction where the moving knife is located, and the thread cutting process of the moving knife moving obliquely towards the fixed knife can be realized. In addition, the moving knife guiding can also be set in an arc direction. In another embodiment (such asFigure 10 ), the moving knife is designed as an arc structure. The circular arc trajectory of the arc movement of the moving knife towards the fixed knife intersects with the Y-axis axis of the embroidery machine where the needle plate hole is located. The fixed knife is arranged at one end of the arc of the moving knife. At this time, both the second base 4 and the third base 5 are arranged in the arc direction of the moving knife, and the process of cutting the thread with the moving knife moving in an arc towards the fixed knife can be realized. In this embodiment, the center of the moving knife movement trajectory does not coincide with the axis of the knife rod of the moving knife driving mechanism (when the coincidence scheme is adopted, the bottom thread to be cut cannot be picked up at the best angle. For details, refer to Figure 1 in case c and its related content analysis). The above three embodiments are all applicable to embroidery machines with a small head distance (such as a head distance less than 60 cm).

[0049] In one embodiment, the fixed knife can be installed at the bottom of the embroidery machine needle plate through the fixing block 6. In this embodiment, the cooperation between the fixed knife and the moving knife can be ensured to be more unified. In another embodiment, the fixed knife can be installed on the shuttle bed through a bracket. In another embodiment, the fixed knife can be directly installed at the bottom of the embroidery machine needle plate. In another embodiment, the fixed knife can be directly installed on the shuttle bed. The above methods are all applicable to the fixed knife installation scheme in the negative Y-axis direction or the positive Y-axis direction.

[0050] As Figure 2-6 , the moving knife driving mechanism includes a knife rod 31, a swing arm 32, and a rotating shaft connecting rod 33. The knife rod 31 is vertically arranged on the shuttle bed 2. The lower end of the knife rod 31 is connected to the rotating shaft connecting rod 33. The upper end of the knife rod 31 is connected to one end of the swing arm 32. The other end of the swing arm 32 has a driving part. When the knife rod 31 drives the swing arm 32 to swing, the driving part drives the moving knife to move. The driving part can be components such as a pin, a ball, a bearing, a pin, etc. Correspondingly, a chute 101 is provided on the moving knife 10 (such as Figure 7 ), and the driving part slides in the chute to drive the moving knife to move. Conversely (such as Figure 11 ), a chute is provided on the swing arm, and a driving part is provided on the moving knife, such as components such as a pin, a pin, a ball, a bearing, etc. The driving part 01 on the moving knife slides in the chute 02 on the swing arm, and the swing arm drives the moving knife to move. Further, the moving knife driving mechanism further includes a mounting plate for mounting the knife rod 31, or a knife rod mounting platform is provided on the shuttle bed as described above. The present invention is not limited to the above moving knife driving mechanism. The moving knife driving mechanism can also adopt other driving mechanisms that can drive the moving knife towards the fixed knife, such as a cylinder driving mechanism or a motor driving mechanism, etc. The moving knife driving mechanism can be arranged on the front side of the shuttle bed, or on the rear side of the shuttle bed, or at the bottom of the needle plate. The present invention is not limited to the above moving knife driving mechanism. The moving knife driving mechanism can adopt a fork structure to realize the driving of the moving knife, or can also adopt a driving shaft structure to realize the driving of the moving knife.

[0051] The thread cutting device of the small head pitch embroidery machine of the present invention further includes a second base 4 and a third base 5 installed at the bottom of the needle plate of the embroidery machine. The second base is located at the front end of the swinging direction of the swing arm, and the third base is located at the rear end of the swinging direction of the swing arm. The moving knife passes through the second base and the third base. Alternatively, it further includes a guide rail installed at the bottom of the needle plate. The guide rail is provided with a space allowing the swing arm to swing. The guide rail extends from the front end of the swinging direction of the swing arm to the rear end of the swinging direction of the swing arm. The moving knife passes through the guide rail.

[0052] Figure 6 It can be seen that in the thread cutting device of the present invention, the spatial position of the fixed knife is slightly higher than that of the moving knife, that is, the fixed knife is located above the moving knife. The present invention is not limited to the above spatial position, and the positions of the fixed knife and the moving knife can also be interchanged, as long as the moving knife moves towards the fixed knife, and when the fixed knife and the moving knife coincide, the cutting edges of the fixed knife and the moving knife cooperate to cut the embroidery thread.

[0053] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the drawings are only examples and do not limit the present invention. The object of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been shown and described in the embodiments. Without departing from the above principles, the embodiments of the present invention can have any deformation or modification.

Claims

1. A thread cutting device for a small head pitch embroidery machine, comprising a moving knife, a fixed knife, and a moving knife driving mechanism; characterized in that, The moving knife and the fixed knife are both arranged at the bottom of the embroidery machine needle plate. The moving knife and the fixed knife are respectively arranged on both sides of the needle plate hole and on both sides in the positive and negative directions of the Y-axis of the embroidery machine. The moving knife driving mechanism is arranged on the shuttle bed. The moving knife cutting end of the moving knife facing the fixed knife has an inclined surface that slopes downward. A groove is formed on the inclined surface. A notch for forming the moving knife cutting end head is formed at the front end of the moving knife cutting end. The groove forms a moving knife blade on the other side away from the moving knife cutting end head. The fixed knife has a fixed knife blade at the bottom of the fixed knife cutting end facing the moving knife. The moving knife driving mechanism drives the moving knife to move linearly towards the fixed knife. When moving, the moving knife cutting end head of the moving knife forks out the bottom thread and the surface thread to be cut and continues to move towards the fixed knife. Until the moving knife coincides with the fixed knife, the moving knife blade and the fixed knife blade act together to cut the bottom thread and the surface thread. The positive direction of the Y-axis is the same as the direction of the front of the machine needle, and the negative direction of the Y-axis is the same as the direction of the back of the machine needle. The moving knife driving mechanism includes a knife rod, a swing arm, and a rotating shaft connecting rod. The movement trajectory of the knife rod of the moving knife driving mechanism is separated from the movement trajectory of the moving knife. A sliding groove is arranged on the moving knife.

2. The thread trimming device of a small head pitch embroidery machine according to claim 1, wherein, The groove wall at the other end of the groove away from the moving knife cutting end head and the inclined surface form the moving knife blade.

3. The thread cutting device for a small head pitch embroidery machine according to claim 2, characterized in that, A concave hole or a through hole is arranged at the bottom of the groove at the other end of the groove away from the moving knife cutting end head. The hole wall of the concave hole and the inclined surface form the moving knife blade, or the hole wall of the through hole and the inclined surface form the moving knife blade.

4. The thread cutting device of a small head pitch embroidery machine according to claim 1, characterized in that, The front end of the fixed knife cutting end has an extension extending towards the moving knife, so that the fixed knife blade is retracted into the extension.

5. The thread cutting device of a small head pitch embroidery machine according to claim 1, characterized in that, The swing arm of the moving knife driving mechanism slides in the sliding groove to drive the moving knife to move.

6. The thread trimming device for a small head pitch embroidery machine according to claim 1, characterized in that, It further includes a first base installed at the bottom of the embroidery machine needle plate. The first base is used to support the moving knife when the moving knife coincides with the fixed knife, so that the moving knife blade can interact with the fixed knife blade to cut the bottom thread and the surface thread.

7. The thread trimming device of a small head pitch embroidery machine according to claim 6, characterized in that, The first base is an elastic component; or, an elastic component is arranged inside the first base, and the elastic component acts on the moving knife.

8. A thread trimming device for a small head pitch embroidery machine according to claim 1 or 6, characterized in that, It further includes a second base or a third base installed at the bottom of the embroidery machine needle plate, and the moving knife passes through the second base or the third base. The moving knife driving mechanism drives the moving knife to move along the guiding direction of the second base or the third base; it further includes a second base or a third base installed on the shuttle bed, and the moving knife passes through the second base or the third base. The moving knife driving mechanism drives the moving knife to move along the guiding direction of the second base or the third base.

9. A thread trimming device for a small head pitch embroidery machine according to claim 1 or 6, characterized in that, Further included are a second base and a third base installed at the bottom of the embroidery machine needle plate, and the moving knife passes through the second base and the third base, and the second base and the third base are used to guide the moving direction of the moving knife; or, further included are a second base or a third base installed at the bottom of the embroidery machine needle plate, and a third base or a second base installed on the bobbin case, and the moving knife passes through the second base and the third base, and the second base and the third base are used to guide the moving direction of the moving knife; or, further included are a second base or a third base partially installed at the bottom of the embroidery machine needle plate and partially installed on the bobbin case, and a third base or a second base installed at the bottom of the embroidery machine needle plate, and the moving knife passes through the second base and the third base, and the second base and the third base are used to guide the moving direction of the moving knife; or, further included are a second base or a third base partially installed at the bottom of the embroidery machine needle plate and partially installed on the bobbin case, and a third base or a second base installed on the bobbin case, and the moving knife passes through the second base and the third base, and the second base and the third base are used to guide the moving direction of the moving knife.

10. The thread trimming device of a small head pitch embroidery machine according to claim 1, characterized in that, The fixed knife is installed at the bottom of the embroidery machine needle plate through a fixing block; or, the fixed knife is directly installed at the bottom of the embroidery machine needle plate or on the bobbin case; or, the fixed knife is installed on the bobbin case through a bracket.

11. A thread cutting device for a small head pitch embroidery machine according to claim 1, characterized in that, The knife rod is vertically arranged on the bobbin case, the lower end of the knife rod is connected to a rotating shaft connecting rod, and the upper end of the knife rod is connected to one end of a swing arm. When the knife rod drives the swing arm to swing, a driving member drives the moving knife to move.

12. A thread trimming device for a small head pitch embroidery machine according to claim 11, characterized in that, Further included are a second base and a third base installed at the bottom of the embroidery machine needle plate. The second base is located at the front end in the swinging direction of the swing arm, and the third base is located at the rear end in the swinging direction of the swing arm. The moving knife passes through the second base and the third base; or, further included is a guide rail installed at the bottom of the needle plate. The guide rail is provided with a space allowing the swing arm to swing. The guide rail extends from the front end in the swinging direction of the swing arm to the rear end in the swinging direction of the swing arm. The moving knife passes through the guide rail.

13. The thread trimming device of a small head pitch embroidery machine according to claim 1, characterized in that, The linear trajectory of the linear motion of the moving knife towards the fixed knife is parallel to the Y-axis axis of the embroidery machine where the needle plate hole is located, or, the linear trajectory of the linear motion of the moving knife towards the fixed knife intersects the Y-axis axis of the embroidery machine where the needle plate hole is located.

14. A thread cutting device for a small head pitch embroidery machine according to claim 1, characterized in that, The fixed knife is arranged at the bottom of the embroidery machine needle plate in front of the embroidery machine rotary hook; the moving knife is arranged at the bottom of the embroidery machine needle plate above the embroidery machine rotary hook.

15. A thread cutting device for a small head pitch embroidery machine according to claim 11, characterized in that, When the driving mechanism of the moving knife drives the moving knife to change from a linear motion towards the fixed knife to a circular motion, the axis of the knife rod does not coincide with the center of the moving trajectory of the moving knife.

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