A sewing machine thread trimming structure, a sewing machine thread trimming method, and a sewing machine

Abstract

The sewing machine thread trimming structure comprises a rotating hook and a thread trimming mechanism, the thread trimming mechanism comprises a driving cutter, the driving cutter has a cutter thread separating tip, a first thread separating edge, a second thread separating edge, a cutter thread containing groove, a cutter cutting edge and a bottom thread separating opening; the sewing machine thread trimming structure further comprises a thread separating hook fixedly arranged with the driving cutter, the thread separating hook has a hook thread tip part, the hook thread tip part is arranged on the inner circumferential side of the driving cutter and on the side of the bottom thread separating opening away from the cutter thread containing groove, there is a thread passing space between the hook thread tip part and the driving cutter, there is a thread separating thread containing groove between the hook thread tip part and the bottom thread separating opening, and the thread separating thread containing groove is communicated with the thread passing space. The application can avoid the bottom thread end from the needle plate falling needle hole with the face thread end, can avoid the bottom thread end of the sewing product from being too long when sewing again, can limit the bottom thread end without clamping effect, and finally improves the thread feeding rate of the bottom thread when sewing.

Description

TECHNICAL FIELD

[0001] The present application relates to the sewing machine technical field, and particularly relates to a sewing machine thread cutting structure, a sewing machine thread cutting method using the sewing machine thread cutting structure and a sewing machine comprising the sewing machine thread cutting structure. BACKGROUND

[0002] The sewing machine is a machine for forming one or more stitches on a cloth by using one or more sewing threads to interweave or sew one or more layers of sewing materials. The sewing machine usually has an automatic thread cutting device arranged on the bottom surface side of the bottom plate. The automatic thread cutting device cuts the thread (including the top thread and the bottom thread) by rotating the movable cutter around the lower shaft of the sewing machine. However, the top thread and the bottom thread are accommodated in the thread accommodation groove of the movable cutter before being cut. Therefore, the thread ends of the top thread and the bottom thread are adhered together after being cut. Thus, when the needle pulls out the top thread from the needle drop hole of the needle plate, the thread end of the bottom thread adhered together with the top thread will be pulled out and stay in an arbitrary direction, which results in the uncertainty of the position of the top thread loop around the thread end of the bottom thread when the sewing machine starts to sew again. Therefore, the sewing materials cannot be interwoven, which results in the sewing defects such as the thread breakage at the beginning of the sewing or the continuous thread breakage. Meanwhile, when the needle pulls out the top thread from the needle drop hole of the needle plate, the thread end of the bottom thread will be pulled out from the needle drop hole of the needle plate without additional resistance, which results in the thread end of the bottom thread being pulled out from the needle drop hole of the needle plate together with the top thread. When the sewing machine starts to sew again, the sewing materials press the thread end of the bottom thread pulled out from the needle drop hole of the needle plate, which results in the problem of the overlong thread end of the bottom thread at the beginning of the sewing. Therefore, the thread end of the bottom thread needs to be trimmed manually, which affects the sewing efficiency.

[0003] In view of the above problems, the sewing machine disclosed in the Chinese Utility Model Patent No. 201220601635.3 has a thread cutting cutter with a bottom thread end positioning function. The thread cutting cutter has a thread passing channel arranged in the thread separation groove, which can position the thread end of the bottom thread during the thread cutting process. However, in actual use, the thread passing channel is arranged in the thread separation groove, which causes the top thread and the bottom thread to enter the thread passing groove together. The thread cutting process cannot separate the top thread and the bottom thread. When the top thread is pulled out, the bottom thread adhered together with the top thread will be pulled out together, which cannot position the bottom thread stably.

[0004] There is also a thread cutting technology, after the thread cutting is completed, the sewing machine is cut off by the spring and the movable knife or the fixed knife, the thread end is clamped, the positioning of the thread end can be effectively realized, and the problem that the thread end is pulled out from the needle plate and the thread end is pulled out from the needle hole is prevented. But in the next sewing, the clamped thread end needs to be pulled out by the interlaced thread after several stitches, which will also cause the same problem as the thread end is pulled out from the needle plate and the needle hole, that is, the problem that the thread end is too long at the sewing position; and when sewing thin materials, forcibly pulling out the clamped thread end will also cause the problem of wrinkles and other adverse phenomena. SUMMARY

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present application is to provide a sewing machine thread cutting structure which can not only prevent the thread end from being pulled out from the needle plate and the needle hole, but also prevent the thread end from being too long at the sewing position during the next sewing.

[0006] To achieve the above-mentioned purpose, the present application provides a sewing machine thread cutting structure, which comprises a rotating hook and a thread cutting mechanism, the thread cutting mechanism comprises a driving knife distributed on the outer peripheral side of the rotating hook and capable of rotating around the rotating hook, the driving knife has a driving knife thread separating tip for inserting into a thread loop, a first thread separating edge and a second thread separating edge both extending from the driving knife thread separating tip, a driving knife thread containing groove and a driving knife cutting edge both arranged on the outer peripheral surface of the driving knife, and a bottom thread separating port arranged at the joint of the first thread separating edge and the driving knife thread containing groove, the driving knife cutting edge is distributed at the end of the driving knife thread containing groove away from the bottom thread separating port; the sewing machine thread cutting structure further comprises a thread separating hook fixedly arranged with the driving knife, the thread separating hook has a hooking tip portion, the hooking tip portion is distributed on the inner peripheral side of the driving knife facing the rotating hook and on the side of the bottom thread separating port away from the driving knife thread containing groove, a thread passing space is formed between the hooking tip portion and the driving knife, a thread separating thread containing groove is formed between the hooking tip portion and the port wall of the bottom thread separating port, and the thread separating thread containing groove is communicated with the thread passing space.

[0007] Further, the thread separating hook and the driving knife are separate parts, the thread separating hook further has a body mounting portion distributed on the inner peripheral side of the driving knife, and the body mounting portion is fixedly connected with the driving knife.

[0008] Further, the outer peripheral surface of the body mounting portion and the inner peripheral surface of the driving knife are in close contact.

[0009] Further, the thread separating hook and the driving knife are separate parts, the thread separating hook further has a body mounting portion distributed on the inner peripheral side of the driving knife, and the body mounting portion is fixedly connected with the driving knife.

[0010] Further, the end of the hooking tip portion is a bending portion, the bending portion is bent and extends away from the first thread separating edge along the radial direction of the rotating hook, so that a radial opening gap is formed between the bending portion and the first thread separating edge, and the radial opening gap is the thread passing space.

[0011] Further, the bending part spans the first thread separation edge.

[0012] Further, the thread hooking tip part has a bottom thread hooking surface facing the inner wall of the thread separation groove, and a thread separation surface facing away from the outer wall of the thread separation groove, the thread separation surface extending to the thread space.

[0013] The application further provides a sewing machine thread cutting method using the sewing machine thread cutting structure as described above, the sewing machine thread cutting method comprising the following steps:

[0014] S1, in the initial state, the driving knife is distributed on one side of the needle of the sewing machine;

[0015] S2, when starting to cut the thread, the driving knife rotates around the rotating hook, the thread separation tip of the driving knife is inserted into the thread loop of the face thread; along with the rotation of the driving knife, the face thread threaded through the needle of the sewing machine slides along the first thread separation edge and the second thread separation edge, until the face thread on the inner circumferential side of the driving knife enters the thread separation groove of the driving knife through the bottom thread separation port, and the bottom thread threaded through the thread outlet of the rotating hook slides into the thread separation groove, and then enters the thread separation groove of the driving knife through the bottom thread separation port;

[0016] S3, after the driving knife is rotated to the position, the driving knife is located on the other side of the needle beyond the needle, the thread cutting mechanism cuts the face thread and the bottom thread, the thread end of the face thread on the side of the needle after cutting is distributed along the thread separation groove of the driving knife, and the thread end of the bottom thread on the side of the rotating hook after cutting is distributed along the thread separation groove of the driving knife and threaded through the thread separation groove;

[0017] S4, the driving knife reversely rotates and resets to the side of the needle, the thread hook synchronously rotates with the driving knife, the thread hooking tip part hooks the thread end of the bottom thread in the thread separation groove, and pulls the thread end of the bottom thread from the other side of the needle to the side of the needle, and the thread end of the face thread is separated from the thread separation groove, so that the thread end of the face thread and the thread end of the bottom thread are separated.

[0018] The application further provides a sewing machine, wherein the sewing machine thread cutting structure as described above is arranged in the sewing machine.

[0019] As described above, the sewing machine thread cutting structure, the sewing machine thread cutting method and the sewing machine according to the application have the following beneficial effects:

[0020] This application utilizes a thread-separating hook fixed relative to the active blade. During the resetting process after the active blade has finished cutting the thread, the hook tip catches the bottom thread end in the thread-separating groove and pulls it back, thus separating the top thread end from the bottom thread end. This effectively prevents the bottom thread end from protruding from the needle hole of the needle plate as the top thread end is pulled away. Furthermore, the positions of the thread-separating groove when the active blade is in its initial position and when it is in the cutting position are roughly evenly distributed on both sides of the exit of the rotary hook, preventing the bottom thread end from becoming too long. The thread-separating hook has a limiting effect on the bottom thread end but no clamping effect, thus preventing the bottom thread end from becoming too long at the start of the sewn fabric during subsequent sewing and preventing the thin fabric from being wrinkled. Ultimately, this effectively improves the appearance of the starting stitch and reduces the probability of needing to trim the thread end again. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the thread-cutting structure of the sewing machine in this application.

[0022] Figure 2 and Figure 3 This is a schematic diagram of the cooperation between the active blade and the dividing hook in this application from different perspectives.

[0023] Figure 4 for Figure 3 Enlarged view of circle A.

[0024] Figures 5a to 5c This is a schematic diagram of the structure of three embodiments of the active blade in this application.

[0025] Figure 6 and Figure 7 This is a schematic diagram showing the interaction of the dividing lines in this application from different perspectives.

[0026] Figure 8 This is a schematic diagram of the sewing machine thread-cutting structure in the active blade extension state.

[0027] Figure 9 This is a schematic diagram of the sewing machine thread-cutting structure in the active blade return state in this application.

[0028] Component designation explanation

[0029] 10. Rotary Shuttle

[0030] 101 Outlet

[0031] 20 Active Blades

[0032] 21. Moving knife to separate the tip.

[0033] 22 First dividing line edge

[0034] 23 Second dividing line edge

[0035] 24 moving blade line receiving groove

[0036] 25 moving blade edge

[0037] 26 bottom surface line dividing edge

[0038] 30 line dividing hook

[0039] 31 hooking tip

[0040] 311 bent portion

[0041] 312 bottom line hooking surface

[0042] 313 line dividing surface

[0043] 32 line dividing line receiving groove

[0044] 33 body mounting portion

[0045] 40 thread passing space

[0046] 50 needle plate

[0047] 51 needle drop hole

[0048] 60 machine needle

[0049] 70 fixed blade

[0050] 80 bottom line thread end

[0051] 90 surface line thread end DETAILED DESCRIPTION

[0052] The embodiments of the present application will be described in detail by the following specific examples, and other advantages and effects of the present application can be easily understood by those skilled in the art from the contents disclosed in the present specification.

[0053] It should be noted that the structures, proportions, sizes, etc. shown in the drawings of the present specification are merely used to assist in understanding and reading the contents disclosed in the present specification, and are not used to limit the conditions that the present application can be implemented, and therefore do not have technical substantial meanings. Any modification of the structures, change of the proportional relationship, or adjustment of the size, without affecting the effects that the present application can produce and the purposes that the present application can achieve, should still fall within the scope of the technical contents disclosed in the present application. Meanwhile, the terms such as "upper", "lower", "left", "right", "middle", and "one" used in the present specification are merely used for clear description, and are not used to limit the scope of the present application, and the change or adjustment of the relative relationship, without substantially changing the technical contents, should also be considered as the scope of the present application.

[0054] The application provides a sewing machine thread cutting structure, a sewing machine thread cutting method using the sewing machine thread cutting structure, and a sewing machine provided with the sewing machine thread cutting structure. For ease of description, the directions in the following embodiments are defined as follows: the length direction of the sewing machine is defined as the left-right direction, the head side of the sewing machine is the left side, and the tail side of the sewing machine is the right side; the width direction of the sewing machine is defined as the front-rear direction, and the moving direction of the sewing material when the sewing machine is sewing is the front direction; and the height direction of the sewing machine is defined as the up-down direction.

[0055] As shown in Figure 1 , the sewing machine comprises a fixedly arranged bottom plate, a needle plate 50 fixedly arranged at the left end side of the bottom plate, a needle 60 reciprocally movable up and down, a lower shaft rotatably supported in the bottom plate and extending left and right, and a rotating hook 10 fixedly arranged at the left end of the lower shaft, the needle plate 50 is provided with a needle falling hole 51 penetrating up and down, the needle 60 is movably up and down through the needle falling hole 51 of the needle plate 50; the rotating hook 10 has a thread outlet 101 through which the bottom thread passes; the needle 60 cooperates with the rotating hook 10 to interweave the thread passing through the needle 60 with the bottom thread supplied by the rotating hook 10, so as to form a stitch on the sewing material and sew the sewing material.

[0056] As shown in Figure 1 , the sewing machine thread cutting structure provided by the application comprises a rotating hook 10 in the sewing machine, a thread cutting mechanism, and a thread separating hook 30. The thread cutting mechanism comprises a driving knife 20 rotatable, the driving knife 20 is distributed at the outer peripheral side of the rotating hook 10, the inner peripheral surface of the driving knife 20 faces the rotating hook 10, and the outer peripheral surface of the driving knife 20 faces away from the rotating hook 10; the driving knife 20 can rotate around the lower shaft in the sewing machine, that is, the driving knife 20 can rotate around the rotating hook 10; the initial position of the driving knife 20 is distributed at the front side of the needle 60 and the thread outlet 101 of the bottom thread in the rotating hook 10, and the thread cutting position of the driving knife 20 is distributed at the rear side of the needle 60 and the thread outlet 101 of the bottom thread in the rotating hook 10.

[0057] As shown in Figure 5a , or Figure 5b , or Figure 5cAs shown in the figure, the active knife 20 has a dynamic knife split tip 21 for inserting into the thread ring, a first split edge 22 and a second split edge 23 both extending from the dynamic knife split tip 21, a dynamic knife thread storage groove 24 and a dynamic knife blade edge 25 both arranged on the outer peripheral surface of the active knife 20, and a bottom thread split port 26 arranged at the junction of the first split edge 22 and the dynamic knife thread storage groove 24, the first split edge 22 extends forward and circumferentially from the dynamic knife split tip 21 along the rotation path of the active knife 20, the second split edge 23 extends obliquely forward from the dynamic knife split tip 21, the dynamic knife thread storage groove 24 extends circumferentially along the rotation path of the active knife 20 and is distributed on the front side of the first split edge 22, so the bottom thread split port 26 is also distributed at the front end of the first split edge 22 and the rear end of the dynamic knife thread storage groove 24, and the dynamic knife blade edge 25 is distributed at the front end of the dynamic knife thread storage groove 24; that is, the first split edge 22, the bottom thread split port 26, the dynamic knife thread storage groove 24 and the dynamic knife blade edge 25 are arranged in order from back to front.

[0058] As shown in the figure, Figures 2 to 4 The split hook 30 is fixedly arranged with the active knife 20, and the split hook 30 has a hook thread tip part 31; in the radial direction of the rotating hook 10, the hook thread tip part 31 is distributed on the inner peripheral side of the active knife 20 facing the rotating hook 10, that is, the hook thread tip part 31 is distributed between the active knife 20 and the rotating hook 10; in the front-rear direction, the hook thread tip part 31 is distributed on the rear side of the bottom thread split port 26, so that a split thread storage groove 32 is formed between the hook thread tip part 31 and the port wall of the bottom thread split port 26, and the split thread storage groove 32 is distributed on the outer peripheral side of the rotating hook 10; at the same time, a thread passing space 40 is also formed between the hook thread tip part 31 and the active knife 20, and the thread passing space 40 communicates with the split thread storage groove 32. As shown in the figure, Figure 6 and Figure 7 The inner wall surface of the hook thread tip part 31 facing the split thread storage groove 32 is a bottom thread hook surface 312, and the outer wall surface of the hook thread tip part 31 away from the split thread storage groove 32 is a split thread surface 313, which extends to the thread passing space 40. In the thread cutting structure of the sewing machine involved in the present application, the active knife 20 and the split hook 30 jointly constitute a combined split component. The positions of the split thread storage groove 32 when the active knife 20 is in the initial position and the positions of the split thread storage groove 32 when the active knife 20 is in the thread cutting position are roughly evenly distributed on the front and rear sides of the thread outlet 101 of the rotating hook 10.

[0059] Further, the thread cutting mechanism further comprises a thread cutting driving source and a main knife transmission unit transmissionally connected between the thread cutting driving source and the active knife 20, the thread cutting driving source can be an electromagnet or a motor, preferably a stepping motor, and the thread cutting driving source drives the active knife 20 to rotate through the main knife transmission unit. The thread cutting mechanism can be a single active knife structure or a double active knife structure; when the thread cutting mechanism is a single active knife structure, as shown in the figure, Figure 1 The thread cutting mechanism further comprises a fixed knife 70, the fixed knife 70 is fixed on the bottom plate and is distributed on the rear side of the needle 60, and the structure of the active knife 20 is as shown in the figureFigure 5c When the thread trimming mechanism is a double-action knife structure, the thread trimming mechanism further comprises an auxiliary action knife and an auxiliary knife transmission unit which is transmissionally connected between the thread trimming driving source and the auxiliary action knife, the thread trimming driving source drives the auxiliary action knife to rotate around the rotating hook 10 through the auxiliary knife transmission unit, the auxiliary action knife is distributed at the rear side of the needle 60, and the structure of the action knife 20 is as shown in Figure 5a When the sewing machine sews thick material, the structure of the action knife 20 is as shown in Figure 5b The working principle of the thread trimming structure of the sewing machine is described below by taking the thread trimming mechanism as an example of a single-action knife structure.

[0060] The application further provides a thread trimming method of a sewing machine using the thread trimming structure of the sewing machine, the thread trimming method of the sewing machine comprising the following steps:

[0061] In the initial state, the action knife 20 is in an initial position, the action knife 20 is distributed at the front side of the needle 60 and the thread outlet 101 in the sewing machine, the fixed knife 70 is distributed at the rear side of the needle 60 and the thread outlet 101 in the sewing machine, that is, the action knife 20 and the fixed knife 70 are respectively located at the front and rear sides of the needle 60.

[0062] When the thread trimming starts, the action knife 20 rotates backward around the rotating hook 10 towards the fixed knife 70, that is, the action knife 20 rotates backward from the initial position to the thread trimming position, and the action knife 20 is out of the knife; first, the action knife 20 inserts the action knife split thread tip 21 into the thread loop of the face thread; then, with the backward rotation of the action knife 20, the action knife split thread tip 21 cuts the thread loop of the face thread, and the action knife 20 is out of the knife. Figure 8As shown, for the bottom thread: since the thread outlet 101 of the rotary hook 10 is located outside, i.e. left side of the thread containing groove 24, and also outside, i.e. left side of the thread hooking tip 31, under the action of the fast movement of the driving knife 20, the thread ring of the bottom thread slides along the thread separating surface 313 of the thread separating hook 30, and then slides into the thread containing groove 32 through the thread space 40, and then enters the thread containing groove 24 through the bottom thread separating port 26; for the top thread: since the top thread is in the process of winding after being separated, the tension of the top thread ring is low, the top thread hung in the needle 60 of the sewing machine is hung on the thread separating tip 21 of the driving knife 20, slides along the first thread separating edge 22 and the second thread separating edge 23, and is attached to the inner circumferential surface of the driving knife 20, until the top thread on the inner circumferential side of the driving knife 20 enters the thread containing groove 24 through the bottom thread separating port 26. Since the driving knife 20, the thread separating hook 30, and the thread outlet 101 of the rotary hook 10 are distributed from top to bottom, the top thread ring hung on the thread separating tip 21 of the driving knife 20 is above the thread hooking tip 31 of the thread separating hook 30, the remaining top thread not contained in the thread containing groove 24 is distributed on the right side of the thread containing groove 24, and the bottom thread threaded out of the thread outlet 101 of the rotary hook 10 enters the thread containing groove 24 from below the thread separating hook 30 and is distributed on the left side of the thread containing groove 24, so that the separation of the bottom thread and the top thread is realized during the thread separating process of the driving knife 20.

[0063] Step S3, after the driving knife 20 is rotated backward to the position, the driving knife 20 passes the needle 60 backward and is located on the rear side of the needle 60, the driving knife 20 is located at the thread cutting position, the driving knife blade edge 25 on the driving knife 20 engages with the blade edge on the fixed knife 70, and the thread cutting mechanism cuts the top thread and the bottom thread; for the bottom thread at the end of the rotary hook 10 after being cut: the bottom thread is threaded in the thread containing groove 32, and the end of the bottom thread is distributed along the thread containing groove 24; for the top thread at the end of the needle 60 after being cut: the top thread is hung on the first thread separating edge 22 and the second thread separating edge 23 on both sides of the thread separating tip 21, is above the thread hooking tip 31 of the thread separating hook 30, and the end of the top thread is distributed along the thread containing groove 24. Due to the particularity of the formation of the lock stitch of the sewing machine, the end of the bottom thread 80 and the end of the top thread 90 in the thread containing groove 24 during thread cutting are twisted and wound, and most of the sewing thread used is cotton blended thread, which has a certain cotton fiber in diameter, and the wound end of the bottom thread 80 and the end of the top thread 90 have a certain adhesion.

[0064] Step S4, after the thread cutting is completed, the active knife 20 is reversely rotated to the initial position, and then the active knife 20 is forward rotated to the front side of the needle 60; in this process, the thread hook 30 is synchronously forward rotated with the active knife 20, the bottom thread hooking surface 312 of the thread hooking tip 31 hooks the bottom thread end 80 in the thread storage groove 32, and the bottom thread end 80 is pulled from the rear side of the needle 60 to the front side of the needle 60; since the initial position and the thread cutting position of the active knife 20 are substantially uniformly distributed on the front and rear sides of the needle 60 and the thread outlet 101, the bottom thread end 80 at the end of the bottom thread can be kept in the thread storage groove 32, and the face thread end 90 at the end of the face thread is naturally directly separated from the active knife 20 in the resetting process of the active knife 20, and is separated from the driven knife thread storage groove 24, as shown in FIG. 8, so that the face thread end 90 and the bottom thread end 80 wound in the driven knife thread storage groove 24 are separated. Figure 9

[0065] In summary, the thread hook 30 fixed relative to the active knife 20 is arranged, in the resetting process of the active knife 20 after the thread cutting is completed, the thread hooking tip 31 hooks the bottom thread end 80 in the thread storage groove 32 and pulls it back, so that the face thread end 90 and the bottom thread end 80 wound in the driven knife thread storage groove 24 are separated, and the bottom thread end 80 is limited in the thread storage groove 32. In this way, on the one hand, the bottom thread end 80 is effectively prevented from being pulled out of the drop needle hole 51 of the needle plate 50 along with the face thread end 90, so that the bottom thread end 80 pulled out of the drop needle hole 51 is prevented from being pressed by the sewing material, and the bottom thread end 80 is prevented from being left at the starting end of the sewing material; on the other hand, the positions of the thread storage groove 32 in the initial position and the thread cutting position of the active knife 20 are substantially uniformly distributed on the front and rear sides of the thread outlet 101 of the rotating hook 10, so that the distance between the thread storage groove 32 in the thread cutting position of the active knife 20 and the thread outlet 101 is close to the distance between the thread storage groove 32 in the initial position of the active knife 20 and the thread outlet 101, and the active knife 20 pulls the bottom thread end 80 forward in the resetting process, so that the position of the thread hooking tip 31 relative to the thread outlet 101 does not change, the bottom thread is not pulled, the bottom thread end 80 is not too long, the thread hook 30 does not clamp the bottom thread end 80, and the bottom thread end 80 at the starting end of the sewing material is not too long, and the thin sewing material is not wrinkled, so that the appearance of the starting end of the sewing material is effectively improved, and the probability of trimming the thread end again is reduced.

[0066] Further, as shown in FIGS. 1 to 8, the thread hook 30 is arranged on the driven knife 20, and the thread hooking tip 31 of the thread hook 30 is arranged on the driven knife thread storage groove 24 of the driven knife 20. Figure 4 Figure 6 Figure 7 ​​​As shown, the right end of the thread hooking tip 31 is a bent portion 311, which extends in a direction away from the first thread separating edge 22 along the radial direction of the hook 10, so that a radial opening gap is formed between the bent portion 311 and the first thread separating edge 22, which is the thread passing space 40. In particular, the thread hooking tip 31 extends from the left side of the bottom thread separating port 26 to the right side of the first thread separating edge 22, so that the bent portion 311 at the right end of the thread hooking tip 31 extends to the right side of the first thread separating edge 22; in this way, the thread hooking tip 31 and the thread separating thread groove 32 formed between the thread hooking tip 31 and the port wall of the bottom thread separating port 26 form an approximately closed groove while forming the thread passing space 40 through the bent portion 311. In the above step S4, when the driving knife 20 is reset by reverse movement, the thread separating thread groove 32 of the approximately closed groove can capture and hold the bottom thread end 80 in the thread separating thread groove 32, effectively preventing the bottom thread end 80 from escaping from the thread separating thread groove 32, and finally reliably separating the thread end 90 wound in the driving knife thread groove 24 from the bottom thread end 80, and having a good limiting effect on the bottom thread end 80. Moreover, when the thread is pulled out of the drop needle hole 51, the thread tension of the bottom thread and the thread separating thread groove 32 will form a resistance together, so that the bottom thread end 80 of the bottom thread end is always in the thread separating thread groove 32 and will not come out of the drop needle hole 51 of the needle plate 50.

[0067] Further, the thread separating hook 30 and the driving knife 20 have two fixing forms: one is that Figure 2 and Figure 3 , and Figure 6 and Figure 7 As shown, the thread separating hook 30 and the driving knife 20 are separate parts, and the thread separating hook 30 further has a body mounting portion 33 distributed on the inner circumferential side of the driving knife 20, the body mounting portion 33 and the driving knife 20 are fixedly connected, and the fixing mode can be impact welding or bolt fixing; and the outer circumferential surface of the body mounting portion 33 and the inner circumferential surface of the driving knife 20 are in close contact and are both arc surfaces. Two, the thread separating hook 30 and the driving knife 20 are integrated parts, and the thread hooking tip 31 is integrally extended from the inner circumferential surface of the driving knife 20.

[0068] In summary, the present application adds a thread separation hook 30 on the inner circumferential side of the driving knife 20, and the hook thread tip 31 at the end of the thread separation hook 30 cooperates with the driving knife 20 to separate the bottom thread end 80 and the face thread end 90 during the thread cutting process of the thread cutting mechanism; after the thread cutting is finished, the bottom thread end 80 is hooked and kept in the thread separation container groove 32, and the next time the sewing is started, it is ensured that the face thread loop can be accurately sleeved on the bottom thread, preventing the sewing from not taking the bottom thread; the thread separation container groove 32 is set to a structure similar to a closed groove, so that the bottom thread and the face thread have independent thread paths, and the thread separation forms resistance to the bottom thread during the face thread extraction process, avoiding the bottom thread end 80 from being extracted and falling into the needle hole 51; after the thread cutting is finished, the thread separation hook 30 has a good limiting effect on the bottom thread end 80 in the thread separation container groove 32, but does not have clamping force, and at the same time, the bottom thread end 80 is located between the hook thread tip 31 and the driving knife 20, and the face thread loop passes through the space between them, which makes it easier to capture the bottom thread and form interlacing, effectively preventing the sewing from being off-thread and other sewing defects such as poor sewing.

[0069] In summary, the present application effectively overcomes the various shortcomings in the prior art and has a high industrial utilization value.

[0070] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes completed by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A thread trimming structure of a sewing machine, comprising a rotating hook (10) and a thread trimming mechanism, the thread trimming mechanism comprising a driving knife (20) distributed on the outer circumferential side of the rotating hook (10) and capable of rotating around the rotating hook (10), the driving knife (20) having a driving knife thread separating tip (21) for inserting into a thread loop, a first thread separating edge (22) and a second thread separating edge (23) both extending from the driving knife thread separating tip (21), a driving knife thread accommodating groove (24) and a driving knife thread separating edge (25) both provided on the outer circumferential surface of the driving knife (20), and a bottom thread separating edge (26) provided at the joint of the first thread separating edge (22) and the driving knife thread accommodating groove (24), the driving knife thread separating edge (25) being distributed at the end of the driving knife thread accommodating groove (24) away from the bottom thread separating edge (26), characterized in that: The thread separating hook (30) is fixedly arranged with the main driving knife (20), and has a hooking thread tip (31) which is distributed on the inner circumferential side of the main driving knife (20) towards the rotating hook (10) and on the side of the bottom thread separating port (26) away from the driving knife thread containing groove (24), and a thread passing space (40) is formed between the hooking thread tip (31) and the main driving knife (20), and a thread separating thread containing groove (32) is formed between the hooking thread tip (31) and the port wall of the bottom thread separating port (26), and the thread separating thread containing groove (32) is communicated with the thread passing space (40).

2. The sewing machine thread trimming structure according to claim 1, characterized in that: The thread separating hook (30) is a separate part from the main driving knife (20), and the thread separating hook (30) further has a body mounting portion (33) which is distributed on the inner circumferential side of the main driving knife (20), and the body mounting portion (33) is fixedly connected with the main driving knife (20).

3. The sewing machine thread trimming structure according to claim 2, characterized in that: The outer circumferential surface of the body mounting portion (33) is in abutment with the inner circumferential surface of the main driving knife (20).

4. The sewing machine thread trimming structure according to claim 1, characterized by: The thread separating hook (30) is an integral part with the main driving knife (20), and the hooking thread tip (31) is integrally extended from the inner circumferential surface of the main driving knife (20).

5. The sewing machine thread trimming structure according to claim 1 or 2 or 4, characterized by: The end of the hooking thread tip (31) is a bent portion (311) which is bent and extended in a direction away from the first thread separating edge (22) along the radial direction of the rotating hook (10), so that a radial opening gap is formed between the bent portion (311) and the first thread separating edge (22), and the radial opening gap is the thread passing space (40).

6. The sewing machine thread trimming structure according to claim 5, characterized in that: The bent portion (311) spans the first thread separating edge (22).

7. The sewing machine thread trimming structure according to claim 1 or 2 or 4, characterized by: The hooking thread tip (31) has a bottom thread hooking surface (312) which is directed towards the inner wall surface of the thread separating thread containing groove (32), and has a thread separating surface (313) which is directed away from the outer wall surface of the thread separating thread containing groove (32), and the thread separating surface (313) extends to the thread passing space (40).

8. A thread trimming method for a sewing machine, characterized by: The sewing machine thread cutting structure of any one of claims 1-7, the sewing machine thread cutting method comprises the following steps: S1, in the initial state, the main driving knife (20) is distributed on one side of the needle (60) of the sewing machine; S2, when starting to cut the thread, the main driving knife (20) rotates around the rotating hook (10), and the driving knife thread separating tip (21) is inserted into the thread loop of the face thread; along with the rotation of the main driving knife (20), the face thread threaded through the needle (60) of the sewing machine slides along the first thread separating edge (22) and the second thread separating edge (23), until the face thread on the inner circumferential side of the main driving knife (20) enters the driving knife thread containing groove (24) through the bottom thread separating port (26), and the bottom thread threaded through the thread outlet (101) of the rotating hook (10) slides into the thread separating thread containing groove (32) through the thread passing space (40), and then enters the driving knife thread containing groove (24) through the bottom thread separating port (26). S3, after the driving knife (20) is turned to the position, the driving knife (20) is located on the other side of the needle (60), the thread cutting mechanism cuts the face thread and the bottom thread, the face thread end (90) on the side of the needle (60) after cutting is distributed along the driving knife thread storage groove (24), the bottom thread end (80) on the side of the rotating hook (10) after cutting is distributed along the driving knife thread storage groove (24) and is arranged in the thread distribution thread storage groove (32); S4, the driving knife (20) is reversely turned and reset to the side of the needle (60), the thread distribution hook (30) is synchronously turned with the driving knife (20), the thread hooking tip (31) hooks the bottom thread end (80) in the thread distribution thread storage groove (32) and moves the bottom thread end (80) from the other side of the needle (60) to the side of the needle (60), the face thread end (90) is separated from the driving knife thread storage groove (24), so that the face thread end (90) and the bottom thread end (80) are separated.

9. A sewing machine characterized by: The sewing machine is provided with the sewing machine thread cutting structure in any one of claims 1-7.

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