A thread trimming device for an embroidery machine, a thread trimming method for an embroidery machine

Abstract

An embroidery machine thread cutting device and method, belonging to the technical field of embroidery machines. The device comprises a moving cutter, a fixed cutter and a moving cutter driving mechanism, all of which are arranged on a shuttle bed. The moving cutter is installed on a cutter rod of the moving cutter driving mechanism. The moving cutter is provided with a moving cutter blade located on a critical trajectory, or the moving cutter is provided with a moving cutter blade located within the critical trajectory and close to the edge of the critical trajectory. The critical trajectory is a trajectory with the cutter rod shaft as the center and the distance from the center to the needle plate hole as the radius. The moving cutter driving mechanism drives the moving cutter to move towards the fixed cutter. When moving, the moving cutter thread cutting end prongs out the bottom thread and the face thread to be cut and continues to move towards the fixed cutter. When the moving cutter coincides with the fixed cutter, the moving cutter blade and the fixed cutter blade jointly cut the bottom thread and the face thread. The intersection of the moving cutter blade and the fixed cutter blade is close to the needle plate hole. The method is realized based on the above device. The present invention has little change to the existing thread cutting device, and the remaining bottom thread on the back of the fabric after cutting is short, greatly improving the quality of the embroidery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of embroidery machines, and particularly relates to a thread cutting device for an embroidery machine and a thread cutting method for an embroidery machine. BACKGROUND

[0002] At present, for the embroidery machine industry, when completing one graphic unit of an embroidery product and starting to embroider another graphic unit, the face thread and the ground thread below the fabric surface need to be cut. The existing embroidery machine structure includes an embroidery machine head, a thread clamping device, and a thread cutting device. The thread cutting device is used for cutting the thread. Specifically, one face thread driven by a needle of the embroidery machine passes through the fabric surface and is hooked by a shuttle and separated into two strands. The two strands form a loop which wraps the ground thread in the shuttle. After knotting is completed, one strand of the face thread and the ground thread are cut by scissors. The cut strand of the face thread and the ground thread form a thread end which is located below the fabric.

[0003] The existing thread cutting device of the embroidery machine includes a moving cutter, a fixed cutter, and a moving cutter driving mechanism. Common thread cutting devices that do not use a thread separating structure generally have the following types: A. The thread clamping device has fixed the face thread into a triangular-shaped loop, and the ground thread is located in the middle of the triangular-shaped loop. The loop can be divided into a left waist thread segment, a right waist thread segment, and a bottom thread segment. The thread clamping device can separate the face thread into a part to be hooked by the thread cutting device (i.e., the left waist thread segment) and a part to be sent to the face thread clamping part (i.e., the right waist thread segment). The face thread and the ground thread are inserted from the middle of the right waist thread segment, and then the face thread and the ground thread of the left waist thread segment are hooked. B. The ground thread is first hooked out, the thread clamping device fixes the face thread into a triangular-shaped loop, and then the face thread of the left waist thread segment is hooked. In the above-mentioned thread cutting devices that do not use a thread separating structure, the moving cutter and the fixed cutter are at a certain distance from the needle plate hole. In this way, when the moving cutter and the fixed cutter intersect, the cutting edge point deviates from the needle plate hole by a certain distance, resulting in that the bottom thread end left on the back of the fabric after cutting is too long, which affects the quality of the embroidery product. If the moving cutter and the fixed cutter are moved towards the needle plate hole in order to shorten the thread end, there will be an interference problem, that is, the moving track of the moving cutter relative to the fixed cutter interferes with the thread loop formed by the face thread, the moving cutter will hook the thread loop to the back of the moving cutter during the opening process, causing the moving cutter to fail to hook the face thread, or causing the face thread to be hooked off due to interference. Therefore, the existing thread cutting device can only be set at a distance far from the needle plate hole. If only the position of the fixed cutter is moved without changing the position of the moving cutter, that is, only the fixed cutter is moved towards the needle plate hole. Since the moving cutter rotates under the driving of the cutter bar, the moving track of the moving cutter does not change, and the cutting edge point of the moving cutter and the fixed cutter still lies on the moving track of the moving cutter, so the thread end cannot be shortened.

[0004] The applicant's prior invention patent application CN201610611193.3 discloses a high-precision thread cutting method of an embroidery machine, and specifically discloses that the method comprises: driving a thread through a cloth surface on a needle plate by a needle of the embroidery machine to form two threads, the two threads are separated by a shuttle tip, and the thread is rotated at a thread hook to form a loop, the thread on the right side of the thread hook is pulled by a hook knife, the hook knife returns to a stop position to determine the length of the two threads under the cloth surface, and then the thread cutting position of the scissors relative to one thread and the bottom thread is determined to accurately determine the thread cutting length. Although the method can control the thread cutting length, the blade point of the moving knife and the fixed knife is far away from the position of the needle plate hole when cutting the thread, which inevitably leads to the fact that the bottom thread tail left on the reverse surface of the fabric is too long after cutting. SUMMARY

[0005] The present application proposes an embroidery machine thread cutting device and an embroidery machine thread cutting method to solve the problems in the prior art, which makes small changes to the existing thread cutting device and shortens the thread tail after cutting, thereby greatly improving the quality of embroidery products.

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

[0007] An embroidery machine thread cutting device comprises a moving knife, a fixed knife and a moving knife driving mechanism, which are all arranged on a shuttle bed. The moving knife is installed on a knife rod of the moving knife driving mechanism. A moving knife blade is arranged on the moving knife at a critical trajectory, or a moving knife blade is arranged on the moving knife at the critical trajectory and close to the edge of the critical trajectory. The critical trajectory is a trajectory constructed by taking the axis of the knife rod as the center and the distance from the center to the needle plate hole as the radius. The moving knife driving mechanism drives the moving knife to move towards the fixed knife. When moving, the moving knife cutting end of the moving knife forks the bottom thread and the 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 jointly cut the bottom thread and the thread. The intersection of the moving knife blade and the fixed knife blade is close to the needle plate hole.

[0008] The embroidery machine thread cutting device of the present application is a thread cutting device without a thread separation structure, i.e., the moving knife is not provided with a thread separation structure, and the thread on the back side of the shuttle does not need to be pushed to one side of the thread cutting knife opened by using the thread separation structure during the thread cutting process. The embroidery machine thread cutting device of the present application makes small changes to the existing thread cutting device, ensures that the thread cutting moving knife smoothly passes through the thread loop, and solves the problem of the long bottom thread tail left on the reverse surface of the fabric after cutting. The bottom thread tail left on the reverse surface of the fabric after cutting refers to the bottom thread tail and the thread tail, which will be collectively referred to as "thread tail" hereinafter.

[0009] The improvement of the embroidery machine thread cutting device of the present application is not a simple improvement in spatial installation position and size. Figure 1The prior art embroidery machine thread cutting device installed on the embroidery machine is shown in the top view. If the moving knife and the fixed knife of the prior art thread cutting device are shifted close to the direction of the needle plate hole and arranged at a position very close to the needle plate hole, there will be interference problems, and the moving knife cannot smoothly pass through the thread loop to capture the surface thread and the bottom thread to be cut. Moreover, the profile of the moving knife after shifting greatly exceeds the needle plate hole, and when cutting the thread, the surface thread is pushed to the back of the rotating shuttle when the moving knife is opened, and the surface thread cannot be smoothly hooked. If the fixed knife of the prior art thread cutting device is moved close to the direction of the needle plate hole and arranged at a position very close to the needle plate hole, the problem of the length of the thread end is not solved. Since the moving knife rotates under the drive of the knife bar, the swinging track of the moving knife blade does not change, and the blade point of the moving knife and the fixed knife when intersecting is still on the swinging track of the moving knife blade, so the length of the thread end of the bottom surface thread left on the back of the fabric after cutting cannot be shortened. Therefore, simply adjusting the spatial installation position of the prior art embroidery machine thread cutting device cannot solve the problem of the long thread end, and various difficulties exist during the adjustment of the spatial installation position.

[0010] In order to overcome the above problems of interference, surface thread hooking failure and solve the problem of long thread end, the intersection point of the moving knife and the fixed knife cutting the bottom surface thread is arranged as close to the needle plate hole as possible. Since the moving knife rotates in the circumferential direction under the swinging of the knife bar, the position of the intersection point of the moving knife blade and the fixed knife blade is limited to be closer to the critical trajectory, and is preferably on the critical trajectory. Therefore, the following embodiments exist: 1, without changing the fixed knife, only changing the moving knife, mainly changing the arrangement position of the moving knife blade; 2, arranging the fixed knife blade close to the needle plate hole and changing the moving knife, mainly changing the arrangement position of the moving knife blade. The arrangement position of the moving knife blade follows the improvement of the critical trajectory, that is, arranging the moving knife blade on the critical trajectory on the moving knife, or arranging the moving knife blade close to the edge of the critical trajectory within the critical trajectory on the moving knife. The close to the edge of the critical trajectory refers to a position very close to the critical trajectory, and the distance from the critical trajectory is generally not more than 2mm, and the distance within the error range of ±0.5mm is also within the range to be protected by the present application. Since the moving knife of the thread cutting device can smoothly fork the bottom surface thread in the thread loop, the maximum profile size range of the moving knife is limited. When the intersection point of the moving knife and the fixed knife cutting the bottom surface thread meets the condition of the above critical trajectory, and the moving knife can smoothly fork the bottom surface thread, the general size of the moving knife is constrained within this range. Figure 1 、 Figure 2 At this time, the change of the size of the moving knife can be clearly known.

[0011] As a preferred, the end of the fixed knife close to the moving knife is arranged close to the edge of the needle plate hole, so that the fixed knife blade is close to the needle plate hole.

[0012] As a preferred, the distance between the end of the fixed knife close to the moving knife and the edge of the needle plate hole is arranged according to the length of the thread end of the bottom surface thread left on the back of the fabric after cutting.

[0013] As a preference, the intersection point of the moving knife blade and the fixed knife blade is not more than 3.5 mm away from the center of the needle plate hole.

[0014] As a preference, the moving knife has a downwardly inclined inclined surface at the moving knife thread clipping end facing the fixed knife, a groove is formed on the inclined surface, a notch is formed at the front end of the moving knife thread clipping end for forming a moving knife thread clipping end head, a recess or a through hole is formed at the bottom of the groove at the other end of the groove away from the moving knife thread clipping end head, the hole wall of the recess forms a moving knife blade with the inclined surface, or the hole wall of the through hole forms a moving knife blade with the inclined surface; the fixed knife has a fixed knife blade at the bottom of the fixed knife thread clipping end facing the moving knife.

[0015] As a preference, the recess or the through hole is located on the critical trajectory.

[0016] As a preference, the notch is located on the critical trajectory where the recess or the through hole is located.

[0017] As a preference, the position of the outermost moving knife thread clipping end head of the moving knife is beyond the position of the needle plate hole.

[0018] As a preference, the edge profile of the moving knife is configured in a shape that can push the bottom thread to the outside of the rotating hook when the moving knife is opened.

[0019] A thread clipping method of an embroidery machine is implemented based on the above-mentioned thread clipping device of the embroidery machine, the method is applied to the control end of the embroidery machine, and the method comprises the following steps: after the moving knife is controlled to be opened, the needle is controlled to be lowered, and stitch embroidery is completed; when a thread clipping action is performed and a loop is formed, the moving knife is controlled to move towards the fixed knife, the moving knife forks out the bottom thread to be clipped and the face thread and continues to move towards the fixed knife, the bottom thread and the face thread are cut off when the moving knife coincides with the fixed knife; and after the thread clipping is completed and before the next needle is raised, the moving knife is controlled to be opened.

[0020] The thread clipping process of the thread clipping method of the present application is completely different from the existing thread clipping process. The thread clipping process of the thread clipping method of the present application has higher reliability. Because in the existing thread clipping process, the following small probability event may occur: when the moving knife is opened, the face thread is pushed away and cannot be returned, and then the moving knife cannot successfully hook the face thread. When the thread clipping method of the present application is adopted, the moving knife is opened before the needle is lowered, and stitch embroidery can be performed, that is, the face thread does not have the problem of being stuck and not returning, the above-mentioned small probability event is avoided, and the operation reliability is better.

[0021] A thread clipping method of an embroidery machine is implemented based on the above-mentioned thread clipping device of the embroidery machine, the method is applied to the control end of the embroidery machine, and the method comprises the following steps: when a thread clipping action is performed, the moving knife is controlled to be opened before a loop is formed; after the loop is formed, the moving knife is controlled to move towards the fixed knife, the moving knife forks out the bottom thread to be clipped and the face thread and continues to move towards the fixed knife, the bottom thread and the face thread are cut off when the moving knife coincides with the fixed knife.

[0022] The thread cutting process of the thread cutting method is the thread cutting process of the existing embroidery machine thread cutting device. The thread cutting method can be realized based on the improved embroidery machine thread cutting device without changing the control end execution timing of the embroidery machine. The method is widely applicable and easy to implement.

[0023] The thread cutting method has the following beneficial effects:

[0024] The thread cutting device and method for an embroidery machine solve the problem of long thread ends of the bottom surface thread left on the back of the fabric after cutting by the existing thread cutting device with little improvement on the existing thread cutting device of the embroidery machine. The thread cutting device does not need to redesign the thread cutting structure of the embroidery machine, does not need to manufacture a new embroidery machine cooperating with the thread cutting device, and does not need to spend a large amount of cost to improve the thread cutting effect of the embroidery machine, thereby greatly improving the quality of the embroidery product. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 The trajectory shown by the inner circle in the figure is a trajectory constructed by taking the center of the knife bar shaft as the center and the distance from the center to the concave hole or through hole 24 as the radius. The trajectory shown by the outer circle in the figure is a trajectory constructed by taking the center of the knife bar shaft as the center and the distance from the center to the outer edge of the moving knife as the radius.

[0026] Figure 2 The trajectory shown by the inner circle in the figure is a G trajectory constructed by taking the center of the knife bar shaft as the center and the distance from the center to the needle plate hole 4 as the radius. The trajectory shown by the outer circle in the figure is a trajectory constructed by taking the center of the knife bar shaft as the center and the distance from the center to the outer edge of the moving knife as the radius.

[0027] Figure 3 The figure is a structure schematic diagram of the moving knife in the thread cutting device of the embroidery machine.

[0028] Figure 4 The figure is a structure schematic diagram of the fixed knife in the thread cutting device of the embroidery machine.

[0029] Figure 1 、 2 The dimensions shown in the figure are only exemplary and the present application is not limited to the above dimensions. The main purpose is to compare the differences between the thread cutting device of the present application and the existing thread cutting device. As can be seen from the figure, the interval distance between the inner circle trajectory and the outer circle trajectory is significantly shortened after the improvement of the thread cutting device. DETAILED DESCRIPTION

[0030] The following is a specific embodiment of the present application and a further description of the technical solution of the present application in conjunction with the drawings. However, the present application is not limited to these embodiments.

[0031] As Figure 2The embroidery machine thread cutting device comprises a moving cutter 2, a fixed cutter 3 and a moving cutter driving mechanism, which are all arranged on a shuttle bed 1. The moving cutter 2 is installed on a cutter rod of the moving cutter driving mechanism. The moving cutter 2 is provided with a moving cutter blade located on a critical trajectory G; or the moving cutter 2 is provided with a moving cutter blade located in the critical trajectory G and close to the edge of the critical trajectory. The critical trajectory is a trajectory constructed by taking the cutter rod shaft center as a circle center and the distance from the circle center to the needle plate hole 4 as a radius. The moving cutter driving mechanism drives the moving cutter 2 to move towards the fixed cutter 3. When moving, the moving cutter thread cutting end of the moving cutter 2 forks out the bottom thread and the face thread to be cut and continues to move towards the fixed cutter. When the moving cutter coincides with the fixed cutter, the moving cutter blade and the fixed cutter blade jointly cut the bottom thread and the face thread. The intersection point of the moving cutter blade and the fixed cutter blade is close to the needle plate hole 4.

[0032] In an embodiment, the fixed cutter adopts an existing fixed cutter, i.e. the installation position and the structure of the fixed cutter are not changed (see Figure 1 ); and the moving cutter adopts a moving cutter designed according to the present application. The improvement of the moving cutter mainly lies in changing the position of the moving cutter blade. Figure 1 In the embodiment, the installation point of the fixed cutter 3 on the shuttle bed 1 is on a straight line with the cutter rod shaft center. The moving cutter blade located in the critical trajectory G and close to the edge of the critical trajectory is designed on the moving cutter; or the moving cutter blade located on the critical trajectory G is designed on the moving cutter (see Figure 2 ). In this embodiment, the installation position of the moving cutter is not changed, i.e. the position of the cutter rod of the moving cutter driving mechanism is not changed. The present application can also change the installation position of the moving cutter, but at the same time, the position of the cutter rod is changed, the distance between the cutter rod and the needle plate hole is changed, the critical trajectory G is changed, and the position of the moving cutter blade of the moving cutter is changed with the change of the critical trajectory G. Obviously, in the embodiment without changing the installation position of the moving cutter, the change is the least, and the present application can be quickly applied at low cost.

[0033] In another embodiment, the fixed cutter adopts an existing fixed cutter structure, but the installation position of the fixed cutter is changed (see Figure 2), the installation position is offset to the needle plate hole direction; the moving cutter adopts the moving cutter designed according to the application. The installation point of the fixed cutter 3 on the shuttle bed 1 is not in a straight line with the cutter bar axis, and the installation point of the fixed cutter is arranged on the shuttle bed 1 close to the needle plate hole 4. Specifically, the end of the fixed cutter close to the moving cutter is arranged close to the edge of the needle plate hole, so that the fixed cutter blade is close to the needle plate hole. The distance between the end of the fixed cutter close to the moving cutter 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. Specifically, the distance between the intersection point of the fixed cutter blade and the moving cutter blade and the needle plate hole is equal to the length of the bottom thread end left on the reverse side of the fabric after cutting. Based on this, the distance between the end of the fixed cutter close to the moving cutter and the edge of the needle plate hole is adjusted adaptively according to the length of the thread end, so that the fixed cutter blade is also arranged close to the needle plate hole. The improvement of the moving cutter mainly lies in changing the position of the moving cutter blade. The moving cutter blade on the moving cutter is designed to be located in the critical trajectory G and close to the edge of the critical trajectory; or the moving cutter blade on the moving cutter is designed to be located on the critical trajectory G (see Figure 2 ). In this embodiment, the installation position of the moving cutter does not change, that is, the cutter bar of the moving cutter driving mechanism does not change position. The installation position of the moving cutter can also be changed in the application, but at the same time the position of the cutter bar also changes, the distance between the cutter bar and the needle plate hole also changes, and then the critical trajectory G also changes, and the position of the moving cutter blade of the moving cutter changes with the change of the critical trajectory G. Obviously, in the embodiment without changing the installation position of the moving cutter, the change is the least, and it can be applied quickly and at low cost.

[0034] In another embodiment, the fixed cutter 3 has an extended design of one end of the fixed cutter blade, and the designed fixed cutter blade is close to the needle plate hole, and the installation position of the fixed cutter does not change (see Figure 1 ). The channel adopts the moving cutter 2 designed according to the application. Figure 1 Specifically, the end of the fixed cutter close to the moving cutter is arranged close to the edge of the needle plate hole, so that the fixed cutter blade is close to the needle plate hole. The distance between the end of the fixed cutter close to the moving cutter 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. Specifically, the distance between the intersection point of the fixed cutter blade and the moving cutter blade and the needle plate hole is equal to the length of the bottom thread end left on the reverse side of the fabric after cutting. Based on this, the distance between the end of the fixed cutter close to the moving cutter and the edge of the needle plate hole is adjusted adaptively according to the length of the thread end, so that the fixed cutter blade is also arranged close to the needle plate hole.

[0035] In the above three embodiments, the intersection of the moving blade and the fixed blade is not more than 3.5 mm away from the center of the needle plate hole, and the distance within the error range of ±0.5 mm is also within the scope to be protected by the application. In order to avoid interference of the needle plate hole, the thread cannot be too short, which also limits the intersection of the moving blade and the fixed blade cannot be at the needle plate hole.

[0036] Figure 3 A specific moving blade structure is shown. The moving blade 2 has a downwardly inclined inclined surface 22 at the moving blade cutting end facing the fixed blade 3, and a groove 221 is formed on the inclined surface 22. In this way, when the moving blade moves towards the fixed blade, the bottom thread and the face thread to be cut will converge in the groove, and the groove provides space for the embroidery thread, so that the embroidery thread has stretching space in the groove and will not be too tight, avoiding the embroidery thread being cut prematurely after the moving blade and the fixed blade contact; in addition, the inclined surface is provided to avoid the blade of the fixed blade pushing the embroidery thread to directly rub and break. In order to control the length of the cut bottom thread and face thread to be consistent, it is not suitable to be too long or too short, so it is necessary to ensure that the embroidery thread is cut at the intersection of the fixed blade and the moving blade, rather than being cut prematurely during the movement of the moving blade towards the fixed blade (i.e. before the intersection). Therefore, it is necessary to design the structure as above.

[0037] A notch 23 is formed at the front end of the moving blade cutting end 21 to form the moving blade cutting end head 21. The notch can be a U-shaped notch or a V-shaped notch or a circular arc-shaped notch. The figure shows that the front end of the moving blade cutting end is divided into two moving blade cutting end heads by the notch 23, so that one moving blade cutting end head is used to fork the bottom thread, and the other moving blade cutting end head is used to fork the face thread (left waist line segment). The position of the outermost moving blade cutting end head 21 of the moving blade is beyond the position of the needle plate hole 4 (as shown in the figure, the moving blade cutting end head is arranged to the right relative to the needle plate hole), and the position of the inner moving blade cutting end head 21 of the moving blade is not beyond the position of the needle plate hole 4. In this way, the moving blade can successfully fork the bottom thread by using the outermost moving blade cutting end head, and fork the face thread by using the innermost moving blade cutting end head. The present application does not allow both moving blade cutting end heads to exceed the position of the needle plate hole, so that the moving blade cannot successfully fork the bottom and face threads. In addition, the edge profile of the moving blade is arranged to be able to push the bottom thread to the outside of the rotating hook when the moving blade is opened. In this way, it can be ensured that the moving blade can successfully fork the bottom and face threads.

[0038] The notch 23 is located on the critical trajectory of the recess or through hole at the position closest to the recess or through hole. When the notch is a V-shaped notch, the position closest to the recess or through hole is the inflection point of the V-shaped notch (i.e. the tip of the V-shaped notch). In this way, the embroidery thread to be cut can be guided to the moving blade cutting edge.

[0039] The groove 221 is provided with a recess hole 24 or a through hole 24 at the bottom of the groove at the other end of the movable cutter cutting end head 21. The hole wall of the recess hole 24 forms the movable cutter blade with the inclined surface 22, or the hole wall of the through hole forms the movable cutter blade with the inclined surface 22. The fixed cutter 3 is provided with a fixed cutter blade 32 at the bottom of the fixed cutter cutting end 31 facing the movable cutter 2. Preferably, the through hole or the recess hole is an inclined hole to make the movable cutter blade sharper. Based on the above design, the recess hole or the through hole can be arranged on the critical trajectory, or arranged in the critical trajectory G and close to the edge of the critical trajectory.

[0040] Figure 4 The specific fixed cutter structure is shown. The fixed cutter 3 is provided with a fixed cutter blade 32 at the bottom of the fixed cutter cutting end facing the movable cutter 2. The fixed cutter blade is welded to the bottom of the fixed cutter, and the fixed cutter blade is obtained by grinding. In an embodiment, the front end of the fixed cutter cutting end is flush with the front end of the fixed cutter blade 32. In another embodiment, the front end of the fixed cutter cutting end has an extension extending towards the movable cutter, so that the fixed cutter blade 32 is recessed in the extension. In the former embodiment, once the embroidery thread is tightened at the fixed cutter cutting end and the fixed cutter blade before the movable cutter blade intersects with the fixed cutter blade, the embroidery thread will be cut off in advance, or the embroidery thread will be cut. In the latter embodiment, due to the presence of the extension, the extension blocks the advance contact of the embroidery thread with the fixed cutter blade, mainly so that the embroidery thread will not be tightened in advance at the fixed cutter blade to cut the embroidery thread or cut the embroidery thread. At the same time, attention should be paid to the extension not being too long in the latter embodiment. The extension that is too long will first contact the movable cutter blade. During the movement of the movable cutter towards the fixed cutter, there is tension between the extension and the movable cutter blade, which eventually causes the movable cutter blade to cut the embroidery thread in advance. The movable cutter driving mechanism drives the movable cutter to move towards the fixed cutter. When the movable cutter moves, the movable cutter cutting end head forks out the bottom thread and the face thread to be cut and continues to move towards the fixed cutter. When the movable cutter coincides with the fixed cutter, the movable cutter blade and the fixed cutter blade jointly cut the bottom thread and the face thread. In addition, the front end of the fixed cutter cutting end can be a flat surface or a concave surface. When the concave surface is used as the front end of the fixed cutter cutting end, it is convenient for the embroidery thread to gather at the blade edge.

[0041] The movable cutter driving mechanism uses the existing movable cutter driving mechanism, which includes a cutter rod, a swing arm, and a rotating shaft connecting rod. The cutter rod is vertically arranged on the shuttle bed 1. The lower end of the cutter rod is connected to the rotating shaft connecting rod, and the upper end of the cutter rod is connected to one end of the swing arm. The other end of the swing arm has a driving member. When the cutter rod drives the swing arm to swing, the driving member drives the movable cutter to move. The driving member can be a pin, a ball, a bearing, a pin, or the like. The present application does not make detailed description here, please refer to the applicant's previous application patent document.

[0042] The application also provides a thread trimming method of the embroidery machine, which is realized based on the thread trimming device of the embroidery machine. The method is applied to the control end of the embroidery machine, and the method comprises the following steps: after the movable cutter is opened, the needle is controlled to go down, and the stitch embroidery is completed; when the thread trimming action is performed, and after the loop is formed, the movable cutter is controlled to move towards the fixed cutter, the bottom thread and the face thread to be trimmed are forked out and continue to move towards the fixed cutter, and the bottom thread and the face thread are cut off when the movable cutter coincides with the fixed cutter; after the thread trimming is completed, and before the next needle is raised, the movable cutter is controlled to be opened. Specifically, the movable cutter is opened before the needle goes down, and the stitch embroidery is performed; the face thread is brought to the back of the fabric (i.e. the back of the fabric) by one needle before the thread trimming action is performed, the face thread is captured by the shuttle when the thread trimming action needs to be performed, the loop is formed by the thread capturing device (such as the thread fork), then the movable cutter is controlled to move towards the fixed cutter, the bottom thread and the face thread to be trimmed are forked out, and the bottom thread and the face thread are cut off when the blade of the movable cutter intersects with the blade of the fixed cutter. The loop is a triangular loop as described in the background art, which is composed of the face thread. The bottom thread is located at the middle position of the triangular loop.

[0043] The application also provides a thread trimming method of the embroidery machine, which is realized based on the thread trimming device of the embroidery machine. The method is applied to the control end of the embroidery machine, and the method comprises the following steps: before the loop is formed, the movable cutter is controlled to be opened; after the loop is formed, the movable cutter is controlled to move towards the fixed cutter, the bottom thread and the face thread to be trimmed are forked out and continue to move towards the fixed cutter, and the bottom thread and the face thread are cut off when the movable cutter coincides with the fixed cutter. Specifically, the face thread is brought to the back of the fabric (i.e. the back of the fabric) by one needle before the thread trimming action is performed, the movable cutter is first controlled to be opened, then the shuttle captures the face thread, the loop is formed by the thread capturing device (such as the thread fork), then the movable cutter is controlled to move towards the fixed cutter, the bottom thread and the face thread to be trimmed are forked out, and the bottom thread and the face thread are cut off when the blade of the movable cutter intersects with the blade of the fixed cutter. The loop is a triangular loop as described in the background art, which is composed of the face thread. The bottom thread is located at the middle position of the triangular loop.

[0044] The above two thread trimming methods are applicable to the thread trimming device of the embroidery machine. The latter embodiment does not need to change the embroidery operation sequence of the existing embroidery machine, and can directly put the improved thread trimming device into application; the former embodiment needs to change the embroidery operation sequence of the embroidery machine, but can greatly improve the reliability of the thread trimming operation of the embroidery machine, and can avoid the failure of the face thread hooking.

[0045] Those skilled in the art should understand that the embodiments of the application shown in the above description and the drawings are only examples and do not limit the application. The purpose of the application has been completely and effectively achieved. The function and structural principle of the application have been shown and described in the embodiments, and the embodiments of the application can be modified or changed without departing from the principle.

Claims

1. A thread-cutting device for an embroidery machine, comprising a moving blade, a fixed blade, and a moving blade drive mechanism all disposed on a shuttle bed; wherein the moving blade is mounted on the blade shank of the moving blade drive mechanism; characterized in that, The moving blade is provided with a moving blade edge located on the critical trajectory, or the moving blade is provided with a moving blade edge located within the critical trajectory and close to the edge of the critical trajectory; the critical trajectory is a trajectory constructed with the blade shaft axis as the center and the distance from the center to the needle plate hole as the radius; the moving blade drive mechanism drives the moving blade to move towards the fixed blade, during which the moving blade's cutting end forks out the bottom and top lines to be cut and continues to move towards the fixed blade until the moving blade and the fixed blade coincide, at which point the moving blade edge and the fixed blade edge work together to cut the bottom and top lines, and the intersection point of the moving blade edge and the fixed blade edge is close to the needle plate hole; the moving blade's cutting end facing the fixed blade has a downwardly inclined surface, and a groove is formed on the inclined surface. The groove has a recessed hole or a through hole at its bottom on the side away from the end of the moving blade cutting the thread. The wall of the recessed hole and the inclined surface form the cutting edge of the moving blade, or the wall of the through hole and the inclined surface form the cutting edge of the moving blade. The front end of the moving blade cutting the thread has a notch for forming the end of the moving blade cutting the thread. The position of the notch closest to the recessed hole or the through hole is located on the critical trajectory of the recessed hole or the through hole. The position of the outermost moving blade cutting the thread exceeds the position of the needle plate hole, and the outermost moving blade cutting the thread is used to pick up the bottom thread. The position of the inner moving blade cutting the thread does not exceed the position of the needle plate hole, and the inner moving blade cutting the thread is used to pick up the top thread.

2. The embroidery machine thread-cutting device according to claim 1, characterized in that, The fixed blade is positioned close to the edge of the needle plate hole at one end near the moving blade, so that the blade of the fixed blade is close to the needle plate hole.

3. The embroidery machine thread-cutting device according to claim 1, characterized in that, The distance between the end of the fixed blade closest to the moving blade and the edge of the needle plate hole is set according to the length of the bottom thread left on the reverse side of the fabric after cutting.

4. The embroidery machine thread-cutting device according to claim 1, characterized in that, The distance between the intersection point of the moving blade and the fixed blade and the center of the needle plate hole does not exceed 3.5mm.

5. The embroidery machine thread-cutting device according to claim 1, characterized in that, The fixed blade has a fixed blade edge at the bottom of the fixed blade cutting end facing the moving blade.

6. A method for trimming threads on an embroidery machine, implemented based on the thread trimming device of claim 1, wherein the method is applied to the control terminal of the embroidery machine, characterized in that... The method includes: after the moving blade is opened, controlling the needle to press down to complete the stitch embroidery; when performing the thread cutting action and forming a loop, controlling the moving blade to move towards the fixed blade, the moving blade forks out the bottom and top threads to be cut and continues to move towards the fixed blade until the moving blade and the fixed blade overlap, cutting the bottom and top threads; after the thread cutting is completed and before the next stitch begins, controlling the moving blade to open.

7. A method for trimming threads on an embroidery machine, implemented based on the thread trimming device of claim 1, wherein the method is applied to the control terminal of the embroidery machine, characterized in that... The method includes: when performing the thread-cutting action and before forming a thread loop, controlling the moving blade to open; after forming the thread loop, controlling the moving blade to move towards the fixed blade, the moving blade forks out the bottom and top threads to be cut and continues to move towards the fixed blade until the moving blade and the fixed blade overlap, cutting the bottom and top threads.

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