An embroidery machine thread cutting device and an embroidery machine thread cutting method

Abstract

An embroidery machine thread cutting device and a thread cutting method belong 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 is installed on the knife rod of the moving knife driving mechanism; the fixed knife is provided with a through hole behind the cutting edge of the fixed knife; a thread holding structure is arranged between the moving knife and the fixed knife, and the thread holding structure includes a thread holding body that at least partially acts on the upper surface of the moving knife, and the acting part is located in front of the cutting edge of the moving knife; the front end of the thread holding body extends in an upward trend to form the free end of the thread holding structure, and the free end extends into the through hole; the thread holding structure is used to bind the bottom thread and / or the top thread end between the acting part and the moving knife before thread cutting; the moving knife driving mechanism drives the moving knife to move towards the fixed knife. When moving, the moving knife forks out the bottom thread and the top thread to be cut and continues to move towards the fixed knife until the moving knife coincides with the fixed knife, and then cuts the bottom thread and the top thread. The method is realized based on the above device. The present invention prevents the top thread end from being brought into the rotary shuttle to form a new stitch, which affects the quality of the embroidered product.

Description

Technical Field

[0001] The present invention belongs to the technical field of embroidery machines, and particularly relates to an embroidery machine thread cutting device and an embroidery machine thread cutting method. Background Art

[0002] Currently, in the embroidery machine industry, when a piece of embroidery finishes one graphic unit and starts embroidering another graphic unit, it is necessary to cut the upper thread and the bobbin thread under the fabric. Since there are numerous embroidery units and frequent thread cutting is required, the thread ends left after thread cutting are located under the fabric. Generally, after thread cutting on an embroidery machine, a single upper thread driven by the embroidery machine needle passes through the fabric and is then hooked by the rotating hook and separated into front and rear strands. These front and rear strands form a loop that wraps the bobbin thread in the rotating hook. During the process of forming the loop and making a knot, since the end of the upper thread is not constrained, it is easy to have a situation where the embroidery thread cannot be tightened. At this time, the thread ends under the fabric are messy and of different lengths, greatly affecting the quality of the embroidery; and if the stitch is too loose, it is easy for the bobbin thread to break free, resulting in thread off and thread breakage.

[0003] The utility model patent CN201071451Y discloses an embroidery machine thread cutting device, and specifically discloses that the device is composed of a moving knife, a fixed knife, and a moving knife driving mechanism for controlling the movement of the moving knife. The moving knife and the fixed knife are arranged in a moving knife assembly that is also arranged on the needle plate. The moving knife can overlap with the fixed knife under the control of the moving knife driving mechanism. There is also a thread catching device on the needle plate that presses the end of the bobbin thread during the process of the moving knife hooking and cutting the thread. This patent only presses the end of the bobbin thread during the thread cutting process, and does not constrain the end of the upper thread for embroidery after thread cutting. There are still problems such as messy and uneven thread ends caused by the inability to tighten the embroidery thread, and easy breakage of the bobbin thread resulting in thread off and thread breakage.

[0004] The applicant's prior invention application CN 2021101748749 discloses a thread cutting method for an embroidery machine, and specifically discloses that the method includes: Step S10, controlling the needle of the sewing machine to penetrate downward and bringing the end of the top thread below the needle plate; Step S20, after the end of the top thread is brought below the needle plate, controlling the moving knife for thread cutting to hook the end of the top thread and move it towards the fixed knife for thread cutting until it stops at the stop limit where the moving knife for thread cutting and the fixed knife for thread cutting are not closed; at this time, the hooked top thread is limited to the bobbin holder below the moving knife for thread cutting; Step S30, controlling the needle of the sewing machine to penetrate downward to complete the embroidery of at least one stitch; Step S40, controlling the moving knife for thread cutting to move from the stop limit towards the fixed knife for thread cutting, and when the moving knife for thread cutting and the fixed knife for thread cutting are closed, cutting off the end of the top thread. This invention uses the bobbin holder located below the moving knife for thread cutting on the existing embroidery machine to restrain the end of the top thread before thread cutting, and performs thread cutting while both the bobbin thread and the top thread are held by the bobbin holder, which solves to a certain extent the problems of uneven thread ends and too loose stitches that are likely to cause the bobbin thread to break free. In the actual application process, since the bobbin holder is located below the moving knife for thread cutting and the top thread is located between the bobbin holder and the moving knife for thread cutting, after cutting, the end of the top thread is easily bent 180 degrees and faces the direction of the rotary hook, causing a new thread end to form when the loop is put on during the second needle pick-up, affecting the quality of the embroidered product. In addition, after thread cutting is completed, waste will remain on the bobbin holder. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a thread cutting device and a thread cutting method for an embroidery machine, which avoid the mess and uneven lengths of the thread ends below the fabric surface, solve the problems of too loose stitches that are likely to cause the bobbin thread to break free and result in thread breakage or disconnection, and can also prevent the end of the top thread from being brought into the rotary hook to form a new stitch, affecting the quality of the embroidered product.

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

[0007] A thread cutting device for an embroidery machine includes a moving knife, a fixed knife, and a moving knife driving mechanism, all of which are arranged on the shuttle bed; the moving knife is installed on the knife rod of the moving knife driving mechanism; the fixed knife is provided with a through hole on the rear side in the direction of the cutting edge of the fixed knife blade; a thread holding structure is arranged between the moving knife and the fixed knife, and the elastic piece thread holding structure includes a thread holding body, at least part of the thread holding body acts on the upper surface of the moving knife, and the acting part of the thread holding body is located on the front side in the direction of the cutting edge of the moving knife blade; the front end of the thread holding body extends in an upward trend to form the free end of the thread holding structure, and the free end of the thread holding structure extends into the through hole; the thread holding structure is used to restrain the end of the bobbin thread and / or the top thread between the acting part of the thread holding body and the moving knife before thread cutting; the moving knife driving mechanism drives the moving knife to move towards the fixed knife, and when moving, the cutting end of the moving knife for thread cutting forks out the bobbin thread and the top thread to be cut and continues to move towards the fixed knife until the moving knife and the fixed knife coincide, and the cutting edges of the moving knife and the fixed knife act together to cut off the bobbin thread and the top thread.

[0008] The invention utilizes a thread holding structure disposed between the stationary knife and the moving knife, which can effectively restrain the bobbin thread and / or the end of the face thread (i.e., restrain both the face thread and the bobbin thread when starting to sew; after cutting the face thread, restrain the bobbin thread), avoiding the mess of the thread ends under the fabric surface and the uneven lengths of the thread ends, and solving the problems that the stitch is too loose, which easily causes the bobbin thread to break free and result in thread breakage.

[0009] Compared with the prior invention application CN 2021101748749, which uses a bobbin thread holder located below the moving knife to restrain the bottom and face threads, although the prior application can restrain the ends of the bottom and face threads, since the bobbin thread holder is located below the moving knife, the end of the face thread is bent 180 degrees and faces the bobbin case. When starting to sew the second stitch, it will bring up the stitch and form a new thread end, which greatly affects the quality of the embroidery. In this case, instead of using a bobbin thread holder to restrain the bottom and face threads, a thread holding structure is adopted. This thread holding structure is disposed above the moving knife, avoiding bending the end of the face thread by 180 degrees, so that the end of the face thread always keeps away from the direction of the bobbin case, and avoiding the thread end being caught in the thread loop to form a new stitch. At the same time, this thread holding structure can effectively restrain the ends of the bottom and face threads.

[0010] After cutting the thread, waste will be generated. In the prior invention application, the bobbin thread holder is located below the moving knife. When the moving knife is opened for the second time, the waste will remain on the bobbin thread holder and is not easy to remove. While adopting the thread holding structure of the present invention disposed between the stationary knife and the moving knife, after the moving knife is opened for the second time, the waste can be quickly discharged.

[0011] In addition, the present invention can also avoid the bobbin thread being accidentally cut when the moving knife hooks the bobbin thread. Before cutting, one end of the bobbin thread is fixed at the fabric, and the other end is connected to the bobbin in the bobbin case; during the process of the moving knife hooking the bobbin thread, actually, the bobbin thread at the bobbin case is pulled out and then cut. When using the bobbin thread holder in the prior invention application, the bobbin thread between the hooking position of the moving knife and the bobbin case has been pressed by the bobbin thread holder, which is equivalent to this section of the bobbin thread bearing more pressure. When the moving knife continues to move towards the stationary knife, it is easy to be cut in advance when passing through the edge of the stationary knife. While adopting the thread holding structure of the present invention, the bobbin thread between the needle plate and the thread holding structure remains relatively stationary. During the process of the moving knife hooking the bobbin thread, the bobbin thread does not bear more pressure and can be cut when the edges of the moving knife and the stationary knife coincide, and will not be cut in advance during the hooking process.

[0012] Preferably, the thread holding structure is a shrapnel or a fibrous structure.

[0013] Preferably, the rear end of the thread holding body is fixed above the stationary knife, and the thread holding body passes through the through hole above the stationary knife and acts on the upper surface of the moving knife.

[0014] Preferably, the rear end of the thread holding body is fixed on the upper surface of the stationary knife or fixed on the shuttle bed.

[0015] Preferably, the rear end of the embroidery thread holding body is fixed below the fixed knife.

[0016] Preferably, the rear end of the embroidery thread holding body is fixed on the lower surface of the fixed knife or on the shuttle bed.

[0017] Preferably, the through hole is replaced with a blind hole, the blind hole is opened on the lower surface of the fixed knife, and the free end of the embroidery thread holding structure extends into the blind hole; alternatively, the fixed knife provided with a through hole is replaced with a fixed knife without a through hole, and the free end of the embroidery thread holding structure is located between the fixed knife and the moving knife.

[0018] Preferably, the moving knife cutting thread acting portion facing the fixed knife is provided with a downwardly inclined surface, a groove is opened on the inclined surface, a notch for forming the moving knife cutting thread end is opened at the front end of the moving knife cutting thread acting portion, a concave hole or a through hole is provided at the bottom of the groove at the other end away from the moving knife cutting thread end, the hole wall of the concave hole 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 bottom of the fixed knife cutting thread acting portion of the fixed knife facing the moving knife is provided with a fixed knife blade.

[0019] Preferably, the acting portion of the embroidery thread holding body acts on the bottom surface of the groove of the moving knife.

[0020] An embroidery machine thread cutting method is implemented by using the above embroidery machine thread cutting device. The method is applied to the control end of the embroidery machine and includes:

[0021] Step S10, controlling the machine needle to penetrate, and bringing the surface thread end to below the needle plate;

[0022] Step S20, after the surface thread end is brought to below the needle plate, controlling the moving knife to hook the surface thread end and move towards the fixed knife until it stops at the non-closed stop limit between the moving knife and the fixed knife; at this time, the hooked surface thread is limited by the embroidery thread holding structure;

[0023] Step S30, controlling the machine needle to penetrate to complete the embroidery of at least one stitch;

[0024] Step S40, controlling the moving knife to move from the stop limit towards the fixed knife, and when the moving knife and the fixed knife are closed, cutting off the surface thread end.

[0025] The method of the present invention is implemented based on the embroidery machine thread cutting device of the present invention. The embroidery thread holding structure restrains the surface thread during the starting of the needle, facilitating the formation of a tightened surface thread end with a unified length after thread cutting. At the same time, the embroidery thread is tightened, and the surface thread end is not easily broken free from the bottom thread.

[0026] Preferably, step S10 further includes: before the sewing needle passes through the needle plate hole, controlling the moving knife to open so that the top thread can pass through the needle plate hole and pass through the space between the fixed knife and the moving knife, and then enter the rotary hook.

[0027] Preferably, step S10 further includes: after the top thread end is brought below the needle plate and before the next sewing needle passes through the needle plate hole, controlling the moving knife to open so that the top thread can pass through the space between the fixed knife and the moving knife and the top thread can be hooked by the moving knife.

[0028] Preferably, the method further includes: before step S10 controls the sewing needle to penetrate the needle plate hole downward, controlling the top thread gripper to clamp the top thread, and then performing step S10; after step S20 and before step S30 controls the sewing needle to penetrate the needle plate hole downward, controlling the top thread gripper to open to release the top thread, and then performing step S30.

[0029] Preferably, the method further includes: before step S10 controls the sewing needle to penetrate the needle plate hole downward, controlling the top thread gripper to open to release the top thread.

[0030] Preferably, the method further includes: before step S10 controls the sewing needle to penetrate the needle plate hole downward, controlling the top thread gripper to open to release the top thread; when the top thread end is brought below the needle plate and the sewing needle moves back from the lowest position until before step S30 controls the sewing needle to penetrate the needle plate hole downward, controlling the top thread gripper to clamp the top thread; before step S30 controls the sewing needle to penetrate the needle plate hole downward, controlling the top thread gripper to open to release the top thread, and then performing step S30.

[0031] Preferably, step S30 includes: controlling the sewing needle to penetrate downward, controlling the rotary hook to hook the top thread and form a loop, then sleeving the bottom thread, tightening the top thread to complete the embroidery of one stitch; controlling the sewing needle to penetrate downward again, controlling the rotary hook to hook the top thread and form a loop, then sleeving the bottom thread, and tightening the top thread to complete the embroidery of the second stitch.

[0032] Preferably, the method further includes, before step S10, presetting the distance for the moving knife to move from the initial open position to the stop limit position.

[0033] Preferably, the method further includes, before step S10, controlling the embroidery thread holding structure to hold the bottom thread.

[0034] The present invention has the following beneficial effects:

[0035] An embroidery machine thread cutting device and a thread cutting method can prevent the surface thread end from being brought into the rotary hook to form a new stitch, which affects the quality of the embroidered product. Before thread cutting, a thread holding structure is used to hold the surface thread and the bottom thread, ensuring that the embroidery thread is cut under tension, avoiding the bottom thread from breaking free due to too loose a stitch, and then preventing problems such as thread breakage and thread detachment. At the same time, the lengths of the surface thread ends after cutting are consistent, and the thread ends have no fluff, improving the quality of the embroidered product. The present invention can also avoid waste residue after cutting and prevent the bottom thread from being accidentally cut when the moving knife hooks the bottom thread. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 FIG. 6 is a three-dimensional structure diagram (installed on the head of an embroidery machine) of an embroidery machine thread cutting device according to an embodiment of the present invention;

[0037] Figure 2 is Figure 1 a three-dimensional structure diagram of the thread holding structure in FIG. 6;

[0038] Figure 3 is Figure 1 a schematic structural diagram of the fixed knife in FIG. 6;

[0039] Figure 4 is Figure 2 a schematic structural diagram of the cooperation between the thread holding structure and the fixed knife and the moving knife in FIG. 6;

[0040] Figure 5 FIG. 11 is a three-dimensional structure diagram (installed on the head of an embroidery machine) of an embroidery machine thread cutting device according to another embodiment of the present invention;

[0041] Figure 6 is Figure 5 a three-dimensional structure diagram of the thread holding structure in FIG. 11;

[0042] Figure 7 is Figure 6 a schematic structural diagram of the cooperation between the thread holding structure and the moving knife in FIG. 11;

[0043] Figure 8 FIG. 14 is a schematic structural diagram of the moving knife of an embroidery machine thread cutting device according to the present invention;

[0044] Figure 9 FIG. 15 is a flowchart of an embroidery machine thread cutting method according to the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] An embroidery machine thread cutting device according to the present invention (see Figure 1 , 5), including a moving knife 1, a fixed knife 2, and a moving knife driving mechanism 3, all of which are arranged on the shuttle bed 5. The moving knife 1 is installed on the knife rod 31 of the moving knife driving mechanism. The fixed knife 2 is provided with a through hole 21 on the rear side in the direction of the cutting edge of the fixed knife blade 22. A thread holding structure 4 is arranged between the moving knife 1 and the fixed knife 2. The thread holding structure 4 includes a thread holding body 41. At least part of the thread holding body acts on the upper surface of the moving knife, and the acting part of the thread holding body is located on the front side in the direction of the cutting edge of the moving knife blade (refer to Figure 4 , Figure 7 ). The front end of the thread holding body extends in an upward trend to form the free end of the thread holding structure. The free end 42 of the thread holding structure extends into the through hole 21. The thread holding structure is used to bind the bottom thread and / or the top thread end between the acting part of the thread holding body and the moving knife 1 before cutting the thread. The moving knife driving mechanism drives the moving knife 1 to move towards the fixed knife 2. When moving, the cutting end of the moving knife of the moving knife 1 forks out the bottom thread and the top thread to be cut and continues to move towards the fixed knife 2 until the moving knife 1 coincides with the fixed knife 2. The moving knife blade and the fixed knife blade act together to cut the bottom thread and the top thread.

[0046] The thread holding structure can be a shrapnel or a fibrous structure, such as felt or brush, which can have a certain frictional force to ensure that the bottom and top thread ends can be bound before cutting the thread.

[0047] Figure 1-4 This is an embodiment of a thread cutting device of an embroidery machine according to the present invention. The rear end of the thread holding body 41 is fixed above the fixed knife 2. The thread holding body 41 passes through the through hole 21 from above the fixed knife 2 and acts on the upper surface of the moving knife 1. The rear end of the thread holding body can be fixed above the fixed knife 2 by bolts, such as fixed on the upper surface of the fixed knife 2 (see Figure 1 , 4 ), or fixed on the mounting base of the fixed knife 2, or fixed on the shuttle bed 5.

[0048] Figure 2 In, the thread holding body of the thread holding structure includes a mounting portion 411, a connecting portion 412, and an acting portion 413. The mounting portion has a mounting hole. The connecting portion 412 connects the mounting portion 411 and the acting portion 413. The connecting portion 412 extends downward from the mounting portion 411 and passes through and then connects to the acting portion 413. In the figure, the acting portion is a bent structure, and its bent surface acts on the surface of the moving knife. The present invention is not limited to the structure that the thread holding body acts on the surface of the moving knife being a bent structure, nor limited to the bent surface acting on the surface of the moving knife. The acting surface of the acting portion can also be a plane or an inclined plane so that the bottom and top thread ends can be bound in the space between the thread holding structure and the moving knife. The front end of the acting portion extends in an upward trend to form the free end 42 of the thread holding structure, and the free end can extend into the through hole 21.

[0049] As Figure 3 , a through hole 21 is opened at a position between the fixed knife blade and the fixed knife mounting hole of the fixed knife. In order for the thread holding structure to pass through, the through hole 21 is opened according to the size of the thread holding structure.

[0050] Figure 5-7 This is another embodiment of a thread cutting device for an embroidery machine according to the present invention. The rear end of the thread holding body 41 is fixed below the fixed knife 2. The rear end of the thread holding body can be fixed below the fixed knife 2 by bolts, such as fixed on the lower surface of the fixed knife 2, or fixed on the mounting base of the fixed knife 2 (see Figure 7 ), or fixed on the bobbin case 5.

[0051] Figure 6 In, the thread holding body of the thread holding structure includes a mounting portion 411, a connecting portion 412, and an acting portion 413. The mounting portion 411 has a mounting hole. The connecting portion 412 connects the mounting portion 411 and the acting portion 413, and the connecting portion 412 extends downward through the mounting portion 411 and is connected to the acting portion 413 after passing through. In the figure, the acting portion is a curved structure, and its curved surface acts on the surface of the moving knife. The present invention is not limited to the structure in which the thread holding body acts on the surface of the moving knife being a curved structure, nor is it limited to the curved surface acting on the surface of the moving knife. The acting surface of the acting portion can also be a flat surface or an inclined surface, so that the bottom thread end can be bound in the space between the thread holding structure and the moving knife. The front end of the acting portion extends in an upward trend to form a free end 42 of the thread holding structure, and the free end can extend into the through hole 21.

[0052] As Figure 5 , a through hole 21 is opened at a position between the fixed knife blade 22 and the fixed knife mounting hole of the fixed knife 2. In order for the thread holding structure to pass through, the through hole 21 is opened according to the size of the thread holding structure.

[0053] Figure 5-7 The illustrated embodiment is not limited to using a through hole. Since the thread holding structure is installed below the fixed knife, the through hole can be changed to a blind hole, that is, a hole with a certain depth is opened, and it is only necessary to allow the free end to extend in. Or, without opening any holes, on the premise that normal thread cutting can be performed between the fixed knife and the moving knife, to ensure that there is a certain space to accommodate the thread holding structure to realize the binding of the bottom thread end before thread cutting, no through holes or blind holes can be opened on the fixed knife.

[0054] The above two embodiments both adopt fixed knives and moving knives with substantially the same structure (the difference between the two embodiments lies in whether a through hole is opened on the fixed knife, or the size of the opened through hole).

[0055] As Figure 3 , 5, on the bottom of the fixed knife cutting line acting part of the fixed knife 2 facing the moving knife 1, there is a fixed knife blade 22. The raw material of the fixed knife blade is welded to the bottom of the fixed knife and the fixed knife blade is obtained through grinding. In one embodiment, the front end of the fixed knife cutting line acting part is flush with the front end of the fixed knife blade 22. In another embodiment, the front end of the fixed knife cutting line acting part has an extension part extending towards the moving knife 1, so that the fixed knife blade 22 is retracted into the extension part. 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 cutting line acting part 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 part, the extension part blocks the premature contact between the embroidery thread and 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, in the latter embodiment, it should also be noted that the extension part should not be too long. If the extension part 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 part 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. During the movement, the moving knife cutting line 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, 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 cutting line acting part can be a plane or a concave surface. When the front end of the fixed knife cutting line acting part with a concave surface is adopted, it is convenient for the embroidery thread to converge at the edge of the blade.

[0056] Figure 8 The structural diagram of the moving knife of the thread cutting device of the embroidery machine of the present invention is shown. On the moving knife cutting line acting part of the moving knife 1 facing the fixed knife 2, there is an inclined surface 11 which slopes downwards, and a groove 12 is opened on the inclined surface. In this way, when the moving knife moves towards the fixed knife, the bottom thread and the surface 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 tightened, avoiding premature cutting of the embroidery thread after the moving knife contacts the fixed knife; in addition, by setting the inclined surface, it can be avoided that the blade of the fixed knife pushes the embroidery thread directly to cause friction and breakage. In order to control the lengths of the cut bottom thread and surface thread to be the same, neither too long nor too short, it is necessary to ensure that the embroidery thread is cut when the fixed knife blade intersects with the moving knife blade, rather than being prematurely cut during the movement of the moving knife blade towards the fixed knife blade (i.e., before intersection). Therefore, it is necessary to make the above structural design.

[0057] A notch 13 for forming the moving knife cutting line end 131 is opened at the front end of the moving knife cutting line acting part. 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 moving knife cutting line acting part is divided into two moving knife cutting line ends by using the notch 13. In this way, one moving knife cutting line end is used to fork out the bottom thread, and the other moving knife cutting line end is used to fork out the surface thread (the left waist line segment of the triangular thread loop).

[0058] The groove 12 is provided with a concave hole 14 or a through hole 14 at the bottom of the groove on the other end away from the moving knife thread cutting end 131. The hole wall of the concave hole 14 forms a moving knife cutting edge with the inclined surface 11, or the hole wall of the through hole 14 forms a moving knife cutting edge with the inclined surface 11. Preferably, the through hole or the concave hole is an inclined hole to make the moving knife cutting edge sharper. The acting part of the embroidery thread holding body acts on the bottom surface of the groove of the moving knife (see Figure 4 , 7 ). Specifically, the acting part of the embroidery thread holding body acts on the bottom surface of the groove at the rear side of the notch and in front of the moving knife cutting edge.

[0059] The moving knife driving mechanism adopts an existing moving knife driving mechanism, which includes a knife rod, a swing arm, and a rotating shaft connecting rod. The knife rod is vertically arranged on the shuttle bed 5. The lower end of the knife rod is connected to the rotating shaft connecting rod, and the upper end of the knife rod is connected to one end of the swing arm. The other end of the swing arm has a driving part. When the knife rod drives the swing arm 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. The present invention does not elaborate on this, and for details, refer to the patent documents of the applicant's previous applications.

[0060] As Figure 9 , the present invention also provides an embroidery machine thread cutting method, which is realized by using the above embroidery machine thread cutting device. This method is applied to the control end of the embroidery machine and includes:

[0061] Step S10, controlling the machine needle to penetrate, and bringing the surface thread end to below the needle plate;

[0062] Step S20, after the surface thread end is brought to below the needle plate, controlling the moving knife to hook the surface thread end and move it towards the fixed knife until it stops at the stop limit where the moving knife and the fixed knife are not closed; at this time, the hooked surface thread is limited by the embroidery thread holding structure;

[0063] Step S30, controlling the machine needle to penetrate to complete the embroidery of at least one stitch; Step S40, controlling the moving knife to move from the stop limit towards the fixed knife, and when the moving knife and the fixed knife are closed, cutting off the surface thread end.

[0064] The method of the present invention no longer uses the existing bobbin thread retainer, that is, the bobbin thread retainer structure on the existing embroidery machine thread cutting device is cancelled, and an embroidery machine thread cutting device with an embroidery thread holding structure is adopted. The method of the present invention controls the moving knife to perform two steps, that is, first hook and move the surface thread to the stop limit for surface thread binding, and then perform the thread cutting action after completing the embroidery of at least one stitch.

[0065] The method of the present invention further includes the step of opening the moving knife to a position exceeding the needle plate hole. In one embodiment, step S10 further includes: before the sewing needle passes through the needle plate hole, controlling the opening of the moving knife so that the upper thread can pass through the needle plate hole and pass through the space between the fixed knife and the moving knife, and then enter the rotary hook. In another embodiment, step S10 further includes: after the upper thread end is brought below the needle plate and before the next sewing needle passes through the needle plate hole, controlling the opening of the moving knife so that the upper thread can pass through the space between the fixed knife and the moving knife and the upper thread can be hooked by the moving knife. The former embodiment is carried out before the operation of bringing the upper thread end below the needle plate is performed, and the latter embodiment is carried out after the upper thread end is brought below the needle plate and before the operation of controlling the moving knife to hook the upper thread end to the stop limit position is performed. The opening degree of the moving knife in the above two embodiments is to ensure that the distance between the cutting moving knife and the cutting fixed knife is large enough and will not interfere with operations such as the next needle. When the existing thread cutting device uses two moving knives, it is necessary to control the opening degree between the two moving knives, such as controlling the two moving knives to open simultaneously, or controlling one moving knife to remain stationary as the cutting fixed knife and controlling the other moving knife to open.

[0066] The method of the present invention further includes control of upper thread clamping. This method is implemented by the upper thread holder on the embroidery machine. The upper thread holder uses the upper thread holder on the existing embroidery machine. Through the coordinated control of upper thread clamping, the present invention ensures that the upper thread can be advantageously constrained and is not easily broken during the constraint. In one embodiment, the method of the present invention further includes: before controlling the machine needle to penetrate the needle plate hole in step S10, controlling the upper thread holder to clamp the upper thread, and then performing step S10; after step S20 and before controlling the machine needle to penetrate the needle plate hole in step S30, controlling the upper thread holder to open to release the upper thread, and then performing step S30. In another embodiment, the method of the present invention further includes: before controlling the machine needle to penetrate the needle plate hole in step S10, controlling the upper thread holder to open to release the upper thread. In another embodiment, the method of the present invention further includes: before controlling the machine needle to penetrate the needle plate hole in step S10, controlling the upper thread holder to open to release the upper thread; when bringing the upper thread end to below the needle plate and starting from the machine needle moving back from the lowest position until before controlling the machine needle to penetrate the needle plate hole in step S30, controlling the upper thread holder to clamp the upper thread; before controlling the machine needle to penetrate the needle plate hole in step S30, controlling the upper thread holder to open to release the upper thread, and then performing step S30. Comparing the three embodiments, the length of the upper thread end under the control of the first embodiment is the shortest and the waste thread is less; in the second embodiment, the upper thread remains in a loose state all the time, the thread take-up lever releases the thread, the machine needle drops, and more upper thread is pulled off. The length of the upper thread end after cutting is the longest and the waste thread is more, and even waste thread accumulation may occur; the control of the third embodiment is relatively complex. The thread released by the thread take-up lever can be clamped by the upper thread holder for a period of time, which can avoid the upper thread hooked by the rotary hook from being pulled back or even leaving the needle plate hole. For the above first and third embodiments, the specific upper thread clamping moment can be determined according to the thread cutting length. Among them, the length of the upper thread end after cutting in the third embodiment is greater than the length of the upper thread end after cutting in the first embodiment and less than the length of the upper thread end after cutting in the second embodiment.

[0067] Completing the stitch embroidery in step S30 is for completing the locking of the upper thread and can ensure that the embroidery thread is tightened and then cut. In one embodiment, step S30 includes: controlling the machine needle to penetrate downward, controlling the rotary hook to hook the upper thread and form a loop, and then covering the bobbin thread, and completing the embroidery of one stitch after tightening the upper thread. In another embodiment, step S30 includes: controlling the machine needle to penetrate downward, controlling the rotary hook to hook the upper thread and form a loop, and then covering the bobbin thread, and completing the embroidery of one stitch after tightening the upper thread; controlling the machine needle to penetrate downward again, controlling the rotary hook to hook the upper thread and form a loop, and then covering the bobbin thread, and completing the embroidery of the second stitch after tightening the upper thread. After completing the embroidery of one stitch, the embroidery thread can be tightened, and then the upper thread end is cut. To ensure that the upper thread can effectively cover the bobbin thread, it is preferred to complete the embroidery of two stitches. The present invention is not limited to completing the embroidery of one stitch or two stitches, and can also complete the embroidery of multiple stitches according to needs to solve the technical problems of the present invention.

[0068] The method of the present invention further includes, before step S10, presetting the distance that the moving knife moves from the initial open position to the stop limit. Since the thread holding structure for holding the bobbin thread is fixed in position, the distance that the moving knife moves from the initial open position to the stop limit is determined according to the distance between the moving knife and the thread holding structure. The distance for the moving knife to move to the stop limit is set according to the rotation angle of the main shaft of the embroidery machine. When a thread cutting stop limit instruction is received, the moving knife is controlled to move to the stop limit according to the preset distance and pause. When a thread cutting action instruction is received, the moving knife moves from the stop limit towards the thread cutting fixed knife to achieve thread cutting.

[0069] The method of the present invention further includes, before step S10, controlling the thread holding structure to hold the bobbin thread.

[0070] The thread clamp and the thread take-up lever mentioned in the present invention are both existing components in the embroidery machine. During embroidery operation, the function of the thread take-up lever is to control the supply and recovery of an appropriate amount of upper thread during each working cycle of the stitch formation process. The stitch pattern of the thread take-up lever for releasing and taking up the thread follows a sine curve. The thread clamp clamps the upper thread during non-embroidery operation and releases the upper thread during embroidery operation. The present invention aims to describe the cooperative control principle of the above components during the thread cutting process. Other control principles during the embroidery process of the embroidery machine are not elaborated here. The working principles of the thread clamp, the thread take-up lever, etc. follow the inherent execution instructions of the embroidery machine.

[0071] 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 said principles, the embodiments of the present invention can have any deformation or modification.

Claims

1. An embroidery machine thread cutting device, comprising a moving knife, a fixed knife, and a moving knife driving mechanism, all of which are arranged on the shuttle bed; the moving knife is installed on the tool bar of the moving knife driving mechanism; characterized in that, The stationary knife is provided with a through hole on the rear side in the direction of the edge of the stationary knife blade; a thread holding structure is arranged between the moving knife and the stationary knife. The thread holding structure includes a thread holding body. At least part of the thread holding body acts on the upper surface of the moving knife, and the acting part of the thread holding body is located on the front side in the direction of the edge of the moving knife blade. The front end of the thread holding body extends in an upward trend to form a free end of the thread holding structure, and the free end of the thread holding structure extends into the through hole. The thread holding structure is used to bind the bottom thread and / or the top thread end between the acting part of the thread holding body and the moving knife before thread cutting. The moving knife driving mechanism drives the moving knife to move towards the stationary knife. When moving, the thread cutting end of the moving knife forks out the bottom thread and the top thread to be cut and continues to move towards the stationary knife until the moving knife coincides with the stationary knife. At this time, the moving knife blade and the stationary knife blade act together to cut the bottom thread and the top thread. The thread holding structure is a shrapnel or fibrous structure.

2. The embroidery machine thread cutting device according to claim 1, characterized in that, The rear end of the thread holding body is fixed above the stationary knife, and the thread holding body passes through the through hole from above the stationary knife and then acts on the upper surface of the moving knife.

3. The embroidery machine thread cutting device according to claim 2, characterized in that, The rear end of the thread holding body is fixed on the upper surface of the stationary knife or fixed on the bobbin case.

4. The embroidery machine thread cutting device according to claim 1, characterized in that, The rear end of the thread holding body is fixed below the stationary knife.

5. The embroidery machine thread cutting device according to claim 4, characterized in that, The rear end of the thread holding body is fixed on the lower surface of the stationary knife or fixed on the bobbin case.

6. The embroidery machine thread cutting device according to claim 4, characterized in that, The through hole is replaced with a blind hole, and the blind hole is opened on the lower surface of the stationary knife. The free end of the thread holding structure extends into the blind hole; or, the stationary knife with a through hole is replaced with a stationary knife without a through hole, and the free end of the thread holding structure is located between the stationary knife and the moving knife.

7. The embroidery machine thread cutting device according to claim 1, characterized in that, The moving knife is provided with a downwardly inclined surface on its thread cutting acting part facing the stationary knife. A groove is opened on the inclined surface. A notch for forming the thread cutting end of the moving knife is opened at the front end of the thread cutting acting part of the moving knife. A concave hole or a through hole is provided at the bottom of the groove at the other end far from the thread cutting end of the moving knife. The hole wall of the concave hole forms the moving knife blade with the inclined surface, or the hole wall of the through hole forms the moving knife blade with the inclined surface. The bottom of the thread cutting acting part of the stationary knife facing the moving knife is provided with a stationary knife blade.

8. The embroidery machine thread cutting device according to claim 7, characterized in that, The acting part of the thread holding body acts on the bottom surface of the groove of the moving knife.

9. An embroidery machine thread cutting method, implemented by using the embroidery machine thread cutting device according to claim 1, the method is applied to the control end of the embroidery machine, characterized in that, The method includes: Step S10, controlling the machine needle to move downward to bring the top thread end below the needle plate. Step S20, after the top thread end is brought below the needle plate, controlling the moving knife to hook the top thread end and move towards the stationary knife until it stops at the stop limit where the moving knife and the stationary knife are not closed. At this time, the hooked top thread is limited by the thread holding structure. Step S30, controlling the machine needle to move downward to complete the embroidery of at least one stitch. Step S40, controlling the moving knife to move from the stop limit towards the stationary knife. When the moving knife and the stationary knife are closed, the top thread end is cut.

10. The embroidery machine thread cutting method according to claim 9, characterized in that, Step S10 further includes: before the machine needle passes through the needle plate hole, controlling the moving knife to open so that the top thread can pass through the needle plate hole and pass through the space between the stationary knife and the moving knife, and then enter the rotary hook.

11. The embroidery machine thread cutting method according to claim 9, characterized in that, Step S10 further includes: after the thread end of the upper thread is brought under the needle plate and before the next sewing needle passes through the needle plate hole, controlling the moving knife to open so that the upper thread can pass through the space between the fixed knife and the moving knife and the upper thread can be hooked by the moving knife.

12. The embroidery machine thread cutting method according to claim 9, characterized in that, Further included: Before step S10 controls the sewing needle to penetrate the needle plate hole downward, controlling the upper thread gripper to clamp the upper thread, and then executing step S10; after step S20 and before step S30 controls the sewing needle to penetrate the needle plate hole downward, controlling the upper thread gripper to open to release the upper thread, and then executing step S30.

13. The embroidery machine thread cutting method according to claim 9, characterized in that, Further included: Before step S10 controls the sewing needle to penetrate the needle plate hole downward, controlling the upper thread gripper to open to release the upper thread.

14. The embroidery machine thread cutting method according to claim 9, characterized in that, Further included: Before step S10 controls the sewing needle to penetrate the needle plate hole downward, controlling the upper thread gripper to open to release the upper thread; After bringing the thread end of the upper thread under the needle plate and starting from the sewing needle moving back from the lowest position to before step S30 controls the sewing needle to penetrate the needle plate hole downward, controlling the upper thread gripper to clamp the upper thread; before step S30 controls the sewing needle to penetrate the needle plate hole downward, controlling the upper thread gripper to open to release the upper thread, and then executing step S30.

15. The embroidery machine thread cutting method according to claim 9, characterized in that,Step S30 includes: controlling the sewing needle to penetrate downward, controlling the rotary hook to hook the upper thread and form a loop, then sleeving the bobbin thread, and completing the embroidery of one stitch after tightening the upper thread; controlling the sewing needle to penetrate downward again, controlling the rotary hook to hook the upper thread and form a loop, then sleeving the bobbin thread, and completing the embroidery of the second stitch after tightening the upper thread.

16. A thread cutting method for an embroidery machine according to claim 9, characterized in that, The method further includes, before step S10, presetting the distance for the moving knife to move from the initial open position to the stop limit position.

17. A thread cutting method for an embroidery machine according to claim 9, characterized in that, The method further includes, before step S10, controlling the embroidery thread holding structure to hold the bobbin thread.

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