Thread trimming structure of sewing machine

Abstract

The utility model provides a thread trimming structure of a sewing machine, and belongs to the technical field of sewing machines. The problems that an existing thread trimming structure is insufficient in working reliability and short in service life are solved. The thread trimming structure of the sewing machine comprises a thread pressing piece, an auxiliary cutter arranged on a machine base and a movable cutter which is located below a needle plate and can vertically swing around a rotating shuttle shaft of the sewing machine, the auxiliary cutter is provided with a thread trimming end with an auxiliary cutter edge, a thread hooking groove is formed in the movable cutter, and a movable cutter edge is formed in the upper edge of the thread hooking groove. When the movable cutter swings upwards, the thread hooking groove can directly face the needle falling hole up and down, when the movable cutter swings downwards, the cutting edge of the movable cutter can be meshed with the cutting edge of the auxiliary cutting edge, the thread pressing piece is movably connected to the upper side face of the movable cutter, and the movable cutter is further provided with a reset spring acting on the thread pressing piece. And when the auxiliary knife edge is meshed with the movable knife edge, the thread trimming end of the auxiliary knife can abut against the lower side face of the thread pressing piece. The working reliability and the service life of the thread trimming structure can be improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to sewing machine technical field relates to a sewing machine's thread cutting structure. BACKGROUND

[0002] Sewing machine is with one or more sewing thread, on the cloth forms one or more stitch, makes two or more cloth interweaving or sews up the equipment. In order to improve sewing efficiency, sewing machine usually is equipped with thread cutting structure, and the sewing thread is cut off automatically through thread cutting structure, reduces the thread in clothes, improves the efficiency of subsequent arrangement.

[0003] The conventional technology of sewing machine is all fixed installation mode, such as the fixed connection of the thread pressing piece on the machine base, so that the moving knife is close to the thread pressing piece, and the sewing thread is pressed by the moving knife and the thread pressing piece. Such as the Chinese patent document discloses a same circle double-knife nest thread cutting mechanism and sewing machine (application number: 202420143812.0), including main cutting line knife, start sewing cutting line knife and thread pressing plate, the main cutting line knife is fixedly arranged as a fixed knife, the thread pressing plate and the main cutting line knife are arranged at the back side of the machine needle, the start sewing cutting line knife is provided with start sewing hooking groove and start sewing blade, and the start sewing blade is engaged with the main cutting line knife by rotating the start sewing cutting line knife towards the main cutting line knife, so that the sewing thread is cut off.

[0004] The thread cutting mechanism has the following problems in actual use: the thread pressing plate is fixed on the main cutting line knife by screws, or directly fixed on the bottom surface of the sewing machine bottom plate. In the process of starting sewing and cutting thread, when the start sewing cutting line knife rotates towards the main cutting line knife and is not engaged, the first thread clamping part of the thread pressing plate needs to slide along the start sewing blade of the start sewing cutting line knife, and then abuts against the second thread clamping part to form a thread clamping gap for clamping the sewing thread. In this process, the start sewing blade of the start sewing cutting line knife is worn, and after long-term use, the start sewing blade becomes blunt, and the thread cutting fails, so that the thread cutting mechanism has the problems of insufficient working reliability and short service life. SUMMARY

[0005] The utility model aims at the above-mentioned problems existing in prior art, and provides a thread cutting structure of sewing machine, which solves the problems of insufficient working reliability and short service life of the existing thread cutting structure.

[0006] The utility model discloses a sewing machine's thread cutting structure, sewing machine includes the base and the needle plate with the needle hole, the thread cutting structure of this cutting thread structure includes the thread pressing piece, sets up the auxiliary cutter on the base and is located the needle plate below and can swing up and down around the rotating shuttle shaft of sewing machine, the auxiliary cutter has a thread cutting end with auxiliary cutter edge, the auxiliary cutter has the thread hooking groove on and the upper edge of thread hooking groove forms the auxiliary cutter edge, when the auxiliary cutter swings up, can make thread hooking groove with the needle hole up and down directly, when the auxiliary cutter swings down, can make its auxiliary cutter edge and auxiliary cutter edge interlock, its characterized in that, the thread pressing piece swing joint is in the upper side of auxiliary cutter, the thread pressing piece still is equipped with the reset spring on the auxiliary cutter and acts on, under the action of external force, the thread pressing piece can overcome the elastic force of reset spring and move to the direction of facing away from auxiliary cutter, when auxiliary cutter edge and auxiliary cutter edge interlock, the thread cutting end of auxiliary cutter can abut with the lower side of thread pressing piece.

[0007] In the thread cutting structure, when the first needle sewing is completed, the thread of the needle is located in the thread hooking groove, at this time, the auxiliary cutter is approached by the downward swing of the auxiliary cutter until the auxiliary cutter edge and the auxiliary cutter edge interlock to cut the sewing thread, and at the same time, the auxiliary cutter and the thread pressing piece press the residual thread end to position the residual thread end, avoid the thread guide rod to move upward to directly take out the thread of the needle from the needle hole, so that the sewing process is stable.

[0008] Since the thread pressing piece in the thread cutting structure is not fixedly installed as in the conventional technology, but is installed on the auxiliary cutter and moves with the auxiliary cutter, therefore, in the whole process of the auxiliary cutter approaching the auxiliary cutter until the two interlock to cut the thread, the thread pressing piece does not contact the auxiliary cutter edge of the auxiliary cutter to cause the abrasion of the auxiliary cutter edge, so that the auxiliary cutter edge always remains sharp and can stably cut the thread, thereby improving the working reliability of the thread cutting structure. However, since the thread pressing piece is installed on the auxiliary cutter and moves with the auxiliary cutter, it is difficult to accurately control the swing stroke of the auxiliary cutter in the process of swinging the auxiliary cutter to the auxiliary cutter, so that the overshoot caused by the too large swing amplitude is inevitable. At this time, if the thread pressing piece is fixedly connected to the auxiliary cutter, the hard impact between the auxiliary cutter and the thread pressing piece will cause damage to the two. In view of this, the thread cutting structure also adopts the structure design that the thread pressing piece is swing connected to the upper side of the auxiliary cutter, and is provided with a reset spring, so that even when the auxiliary cutter overshoots, the auxiliary cutter can push the thread pressing piece to move a little in the direction away from the auxiliary cutter at the moment of contact between the auxiliary cutter and the thread pressing piece to form a buffer, so as to avoid the hard impact between the auxiliary cutter and the thread pressing piece, thereby protecting the auxiliary cutter and the thread pressing piece, prolonging the service life of the two, and further ensuring the long-term good working reliability of the thread cutting structure. When the thread cutting process is completed, the thread pressing piece can be reset under the action of the reset spring after the auxiliary cutter swings back, waiting for the next thread cutting work.

[0009] In the thread cutting structure of the sewing machine, the auxiliary cutter is fixedly connected to the machine base. Preferably, the auxiliary cutter is connected to the machine base by bolts, which can facilitate the installation of the auxiliary cutter and reduce the cost.

[0010] In the thread cutting structure of the sewing machine, the auxiliary cutter is fixedly connected to the machine base. Preferably, the auxiliary cutter is connected to the machine base by bolts, which can facilitate the installation of the auxiliary cutter and reduce the cost.

[0011] In the thread cutting structure of the sewing machine, the auxiliary cutter is fixedly connected to the machine base. Preferably, the auxiliary cutter is connected to the machine base by bolts, which can facilitate the installation of the auxiliary cutter and reduce the cost.

[0012] In the thread cutting structure of the sewing machine, the auxiliary cutter is fixedly connected to the machine base. Preferably, the auxiliary cutter is connected to the machine base by bolts, which can facilitate the installation of the auxiliary cutter and reduce the cost.

[0013] In the thread cutting structure of the sewing machine, the auxiliary cutter is fixedly connected to the machine base. Preferably, the auxiliary cutter is connected to the machine base by bolts, which can facilitate the installation of the auxiliary cutter and reduce the cost.

[0014] In the thread trimming structure of the sewing machine, the lower side of the thread pressing end close to the auxiliary cutter is a pushing inclined surface, and the pushing inclined surface gradually approaches the upper side of the moving cutter from one end close to the auxiliary cutter to the other end. This structure enables the thread pressing piece to be smoothly pushed when the auxiliary cutter swings towards the needle drop hole, and ensures that the thread is stably pressed by the auxiliary cutter and the thread pressing piece during the movement, so as to cooperate with the thread tensioner to collect the thread upwards, make the residual thread on the cloth as short as possible, achieve better bird nest prevention effect, and improve the appearance of sewing.

[0015] In the thread trimming structure of the sewing machine, the moving cutter is provided with a mounting hole, one end of the thread pressing piece is provided with a connecting hole, a hinge element connected with the mounting hole is arranged in the connecting hole, and the thread pressing piece can rotate relative to the hinge element. The hinge element can be a bolt which is screwed through the connecting hole and the mounting hole, or a pin which is riveted through the connecting hole and the mounting hole. Of course, the structure of the hinge element can also be other structures except for the bolt and the pin, as long as the hinge element can realize the hinged installation of the thread pressing piece.

[0016] In the thread trimming structure of the sewing machine, the reset spring is a torsion spring sleeved on the hinge element, one end of the torsion spring is fixed on the moving cutter, and the other end of the torsion spring is fixed on the thread pressing piece. Alternatively, the reset spring is a tension spring arranged on the upper side of the moving cutter, and the two ends of the tension spring are connected to the moving cutter and the thread pressing piece respectively. Through the action of the torsion spring or the tension spring, the thread pressing piece can be reset, so that the lower side of the thread pressing end close to the auxiliary cutter is located above the blade edge of the moving cutter after the thread pressing piece is reset. When the moving cutter swings to the thread trimming position in the direction of the auxiliary cutter, the thread pressing end on the auxiliary cutter can reliably abut against the lower side of the thread pressing piece, so as to stably press the thread.

[0017] In the thread trimming structure of the sewing machine, the auxiliary cutter is a bent strip-shaped metal piece, and the auxiliary cutter includes a flat section arranged perpendicularly to the rotating hook shaft of the sewing machine and an arc-shaped section bent upwards relative to the flat section. The curvature of the arc-shaped section matches the curvature of the upper surface of the moving cutter. The flat section is fixedly connected to the machine base, and the end of the arc-shaped section away from the flat section is the thread trimming end. The lower edge of the end surface of the thread trimming end forms the auxiliary cutter blade edge. The fixedly installed auxiliary cutter is convenient to install and can reduce manufacturing cost. Since the curvature of the arc-shaped section matches the curvature of the upper surface of the moving cutter, the blade edges of the moving cutter and the auxiliary cutter can be tightly engaged when trimming the thread, so as to form effective shearing force and avoid the failure of trimming the thread.

[0018] In the thread cutting structure of the sewing machine, the auxiliary cutter is a strip-shaped metal sheet bent to form, and the auxiliary cutter comprises a flat section parallel to the rotating hook shaft of the sewing machine and an arc section protruding to the side of the flat section, the curvature of the arc section matches the curvature of the upper surface of the moving cutter, one end of the flat section is fixedly connected to the cutter holder, the end of the arc section away from the flat section is the thread cutting end, and the lower edge of the end surface of the thread cutting end forms the auxiliary cutter edge. The auxiliary cutter of the structure is installed in a swingable manner, so that the cutter holder can drive the auxiliary cutter to swing towards the direction close to the needle drop hole, and the residual thread end is short after the thread is cut. Similarly, the auxiliary cutter of the structure is relatively simple to manufacture, and the manufacturing cost can be reduced. Since the curvature of the arc section matches the curvature of the upper surface of the moving cutter, the edge of the moving cutter and the edge of the auxiliary cutter can be tightly engaged during thread cutting, effective shearing force is formed, and the failure of thread cutting is avoided.

[0019] In the thread cutting structure of the sewing machine, the thread pressing piece is slidably connected to the moving cutter in the swing direction of the moving cutter. In the structure, a sliding protrusion can be arranged on the lower surface of the thread pressing piece, a sliding groove is arranged on the moving cutter, the sliding protrusion is slidably connected with the sliding groove, and the sliding installation of the thread pressing piece is realized. In addition, guide pressing strips can be arranged on the front and rear sides of the thread pressing piece to realize the sliding installation of the thread pressing piece. When the moving cutter overshoots, the auxiliary cutter can push the thread pressing piece to move a little in the direction away from the auxiliary cutter to form a buffer, and the hard impact between the auxiliary cutter and the thread pressing piece is avoided.

[0020] In the thread cutting structure of the sewing machine, the thread pressing piece is slidably connected to the moving cutter in the swing direction of the moving cutter. In the structure, a sliding protrusion can be arranged on the lower surface of the thread pressing piece, a sliding groove is arranged on the moving cutter, the sliding protrusion is slidably connected with the sliding groove, and the sliding installation of the thread pressing piece is realized. In addition, guide pressing strips can be arranged on the front and rear sides of the thread pressing piece to realize the sliding installation of the thread pressing piece. When the moving cutter overshoots, the auxiliary cutter can push the thread pressing piece to move a little in the direction away from the auxiliary cutter to form a buffer, and the hard impact between the auxiliary cutter and the thread pressing piece is avoided.

[0021] In the thread cutting structure of the sewing machine, the thread pressing piece is slidably connected to the moving cutter in the swing direction of the moving cutter. In the structure, a sliding protrusion can be arranged on the lower surface of the thread pressing piece, a sliding groove is arranged on the moving cutter, the sliding protrusion is slidably connected with the sliding groove, and the sliding installation of the thread pressing piece is realized. In addition, guide pressing strips can be arranged on the front and rear sides of the thread pressing piece to realize the sliding installation of the thread pressing piece. When the moving cutter overshoots, the auxiliary cutter can push the thread pressing piece to move a little in the direction away from the auxiliary cutter to form a buffer, and the hard impact between the auxiliary cutter and the thread pressing piece is avoided.

[0022] Compared with the prior art, the thread cutting structure of the sewing machine has the following advantages:

[0023] 1、The line structure in this, the line pressing piece is not as the conventional technology is adopted fixed installation mode, but is installed on the moving knife and moves with the moving knife, therefore in the moving knife close to the auxiliary knife movement until the two are engaged and cut the whole process of the face line, the line pressing piece does not contact the moving knife edge of the moving knife and cause the wear of the moving knife edge, ensure that the moving knife edge always keeps sharp and can stably cut the face line, thereby improving the working reliability of the line structure.

[0024] 2、The line structure still adopts the structure design of the line pressing piece hinged on the upper side of the moving knife, and is provided with a reset spring, so that even if the moving knife overshoots, the auxiliary knife can push the line pressing piece to swing slightly in the direction away from the auxiliary knife and form a buffer when the auxiliary knife contacts the line pressing piece, avoiding the hard impact of the auxiliary knife and the line pressing piece, thereby protecting the auxiliary knife and the line pressing piece, prolonging the service life of the two, so that the line structure has the advantage of long service life.

[0025] 3、The line structure can make the residual thread on the cloth shorter, realize better bird nest prevention effect, and improve the beauty of sewing. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is the front view of the line structure embodiment one.

[0027] Figure 2 is the three-dimensional structure schematic diagram of the line structure in embodiment one when the line pressing piece is in the reset state.

[0028] Figure 3 is the explosion view of the moving knife, the line pressing piece, the reset spring and the hinge in embodiment one.

[0029] Figure 4 is the plan view of the line structure in embodiment one after the auxiliary knife pushes the line pressing piece to swing upward.

[0030] Figure 5 is Figure 4 the sectional view of A-A in

[0031] Figure 6 is the structure schematic diagram of the line pressing piece in the line structure.

[0032] Figure 7 is the structure schematic diagram of the auxiliary knife in embodiment one.

[0033] Figure 8 is the three-dimensional structure schematic diagram of the line structure embodiment two.

[0034] Figure 9 is the structure schematic diagram of the line structure embodiment four.

[0035] Figure 10is a schematic diagram of the three-dimensional structure of the fifth embodiment of the thread trimming structure.

[0036] Figure 11 is a diagram of the cooperation between the auxiliary knife and the thread pressing piece after the moving knife swings downward in the fifth embodiment of the thread trimming structure.

[0037] Figure 12 is a schematic diagram of the three-dimensional structure of the sixth embodiment of the thread trimming structure.

[0038] In the figure, 1 is a machine base; 2 is a needle plate; 21 is a needle drop hole; 3 is a thread pressing piece; 31 is a thread pressing end; 32 is a pushing inclined surface; 33 is a connecting hole; 4 is an auxiliary knife; 41 is a straight section; 42 is an arc section; 421 is a thread trimming end; 422 is an auxiliary knife cutting edge; 423 is a thread pressing groove; 5 is a moving knife; 51 is a thread hooking groove; 52 is a moving knife cutting edge; 53 is a mounting hole; 54 is a limiting protrusion; 6 is a knife holder; 7 is an avoiding gap; 8 is a reset spring; 9 is a hinged piece; 10 is a rotating shuttle; 11 is a needle; 12 is a thread guide piece; 121 is a thread guide groove; 13 is a knife holder seat; 14 is a moving knife mounting frame. DETAILED DESCRIPTION

[0039] The following is a specific embodiment of the utility model and further describes the technical scheme of the utility model in combination with the drawings, but the utility model is not limited to these embodiments.

[0040] Embodiment one

[0041] As shown in Figure 1 and Figure 2 , the sewing machine comprises a machine base 1, a rotating shuttle 10 with a rotating shuttle 10 shaft, a needle plate 2 with a needle drop hole 21, a thread trimming structure comprising a thread pressing piece 3, an auxiliary knife 4, a knife holder seat 13 fixedly arranged on the machine base 1, a ring-shaped moving knife mounting frame 14 rotatably arranged on the knife holder seat 13, and a moving knife 5 fixedly connected to the moving knife mounting frame 14, so that the moving knife is located below the needle plate 2 and can swing up and down around the rotating shuttle 10 shaft, the auxiliary knife 4 has a thread trimming end 421 with an auxiliary knife cutting edge 422, the moving knife 5 has a thread hooking groove 51 and the upper edge of the thread hooking groove 51 forms a moving knife cutting edge 52, the thread hooking groove 51 can be vertically opposite to the needle drop hole 21 when the moving knife 5 swings upward, the moving knife cutting edge 52 can be engaged with the auxiliary knife cutting edge 422 when the moving knife 5 swings downward, the thread pressing piece 3 is hinged to the upper side of the moving knife 5, and the moving knife 5 is further provided with a reset spring 8 acting on the thread pressing piece 3, the thread pressing piece 3 can swing in a direction away from the auxiliary knife 4 against the elastic force of the reset spring 8 under external force, and the thread trimming end 421 of the auxiliary knife 4 can abut against the lower side of the thread pressing piece 3 when the auxiliary knife cutting edge 422 is engaged with the moving knife cutting edge 52.

[0042] As shown in Figure 2As shown, the shearing line structure further comprises a holder 6 arranged on the holder seat 13 and capable of swinging around the axis of the shuttle 10, and the auxiliary knife 4 is fixedly connected to the holder 6. The rotation center line of the holder 6 and the movable knife mounting frame 14 coincides with the axis of the shuttle 10, and the holder 6 and the movable knife mounting frame 14 are driven to rotate by a driving source such as a motor, an electromagnet or a pneumatic cylinder connected to the holder 6 and the movable knife mounting frame 14 respectively. The structure of the driving source driving the holder 6 and the movable knife mounting frame 14 to rotate can adopt the prior art, and will not be described here in detail, and the driving source is not shown in the figure.

[0043] As shown in Figure 3 , the pressing piece 3 is in the shape of a strip, one end of the pressing piece 3 is hingedly connected to the movable knife 5, and the other end is a pressing end 31, the movable knife 5 is provided with a limiting protrusion 54, and under the elastic action of the return spring 8, the side edge of the pressing piece 3 close to the auxiliary knife 4 can abut against the limiting protrusion 54, and the lower side of the pressing end 31 close to the auxiliary knife 4 is located above the movable knife cutting edge 52. When the pressing piece 3 is not subjected to the pushing force of the auxiliary knife 4, the pressing piece 3 can always abut against the limiting protrusion 54 under the action of the return spring 8, and the pressing piece 3 is positioned, so that the lower side of the pressing end 31 of the pressing piece 3 close to the auxiliary knife 4 is located above the movable knife cutting edge 52, so that when the movable knife 5 swings to the shearing line position in the direction of the auxiliary knife 4, the pressing end 31 of the auxiliary knife 4 can smoothly abut against the lower side of the pressing piece 3, thereby stably pressing the surface thread.

[0044] As shown in Figure 4 and Figure 5 , the lower side of the pressing end 31 close to the auxiliary knife 4 has a clearance 7 with the upper side of the movable knife 5, and when the movable knife 5 swings downward, the pressing end 31 of the auxiliary knife 4 can enter the clearance 7 and make the upper side of the shearing end 421 abut against the lower side of the pressing end 31. Figure 5 and Figure 6 , the lower side of the pressing end 31 close to the auxiliary knife 4 is a pushing inclined surface 32, and the pushing inclined surface 32 gradually approaches the upper side of the movable knife 5 from one end close to the auxiliary knife 4 to the other end.

[0045] As shown in Figure 3 and Figure 6 , the movable knife 5 is provided with a mounting hole 53, and one end of the pressing piece 3 is provided with a connecting hole 33, a hinge 9 connected to the mounting hole 53 is arranged in the connecting hole 33, and the pressing piece 3 can rotate around the hinge 9. The hinge 9 can be a bolt, which is screwed into the mounting hole 53 through the connecting hole 33, or the hinge 9 can be a pin, which is riveted into the mounting hole 53 through the connecting hole 33. Of course, the structure of the hinge 9 can also be other structures except for the bolt and the pin, as long as the hinge 9 can realize the hinged installation of the pressing piece 3. A torsion spring is sleeved on the hinge 9, one end of the torsion spring is fixed to the movable knife 5, and the other end of the torsion spring is fixed to the pressing piece 3.

[0046] As Figure 7 shown, the auxiliary knife 4 is a strip-shaped metal sheet bent to form, and the auxiliary knife 4 includes a flat section 41 arranged in parallel with the axis of the rotating hook 10 and an arc-shaped section 42 protruding to the side relative to the flat section 41, the curvature of the arc-shaped section 42 matches the curvature of the upper surface of the moving knife 5, one end of the flat section 41 is fixedly connected to the knife holder 6, and the end of the arc-shaped section 42 away from the flat section 41 is a thread cutting end 421, and the lower edge of the end surface of the thread cutting end 421 forms an auxiliary knife edge 422.

[0047] The working principle of the thread cutting structure is briefly introduced as follows:

[0048] Before the first needle of the sewing machine is started, the moving knife 5 moves upward, so that the thread hooking groove 51 moves to the position directly below the needle 11 away from the end of the moving knife edge 52, or during the process that the needle 11 of the sewing machine moves downward, the moving knife 5 moves at the same time, so that the thread hooking groove 51 moves to the position directly below the needle 11 away from the end of the moving knife edge 52.

[0049] The sewing machine performs the first needle, the needle 11 passes through the thread hooking groove 51 downward with the thread, then the needle 11 moves upward, when the needle 11 moves to the position above the needle plate 2, the moving knife 5 swings downward with the thread pressing piece 3 to approach the auxiliary knife 4, until the moving knife edge 52 and the auxiliary knife edge 422 are engaged to cut the thread, at the same time, the auxiliary knife 4 and the thread pressing piece 3 press the residual thread.

[0050] After that, as Figure 4 and Figure 5 shown, the moving knife 5 remains stationary, the auxiliary knife 4 swings upward, so that the auxiliary knife 4 and the thread pressing piece 3 press the thread to move to the direction of the needle falling hole 21 of the needle plate 2 as close to the needle falling hole 21 as possible, and cooperate with the thread collecting lever to collect the thread upward, so that the residual thread on the cloth is as short as possible, thereby achieving better bird nest prevention effect, Figure 5 In the figure, the thicker line indicates the cut thread.

[0051] Example Two

[0052] The structure and principle of this embodiment are basically the same as those of example one, the difference lies in that, as Figure 8 shown, the auxiliary knife 4 is a strip-shaped metal sheet bent to form, and the auxiliary knife 4 includes a flat section 41 arranged in parallel with the axis of the rotating hook 10 and an arc-shaped section 42 protruding to the side relative to the flat section 41, the curvature of the arc-shaped section 42 matches the curvature of the upper surface of the moving knife 5, one end of the flat section 41 is fixedly connected to the knife holder 6, and the end of the arc-shaped section 42 away from the flat section 41 is a thread cutting end 421, and the lower edge of the end surface of the thread cutting end 421 forms an auxiliary knife edge 422. The auxiliary knife 4 of this structure is fixedly installed, which is convenient to install and can reduce the manufacturing cost.

[0053] Embodiment three

[0054] The embodiment is basically same as the structure and principle of the embodiment one, and the difference is that the reset spring 8 is a tension spring arranged on the upper side of the moving blade 5, and the two ends of the tension spring are connected to the moving blade 5 and the thread pressing piece 3 respectively. Through the action of the tension spring, the reset of the thread pressing piece 3 can be realized, so that the thread pressing end 31 of the thread pressing piece 3 is located above the moving blade edge 52 after the reset of the thread pressing piece 3, and when the moving blade 5 swings to the thread cutting position, the thread pressing end 31 of the auxiliary blade 4 can reliably abut against the lower side of the thread pressing piece 3, so that the surface thread is stably pressed.

[0055] Embodiment four

[0056] The embodiment is basically same as the structure and principle of the embodiment one, and the difference is that, as shown in the figure, the thread pressing piece 3 is slidingly connected to the moving blade 5 along the swinging direction of the moving blade 5. Figure 9

[0057] Embodiment five

[0058] The embodiment is basically same as the structure and principle of the embodiment one, and the difference is that, as shown in the figure, the thread cutting end 421 of the auxiliary blade 4 has a thread pressing groove 423 penetrating the front and back sides of the auxiliary blade 4 on the end face of the thread cutting end 421, and as shown in the figure, when the moving blade 5 swings downward, the side of the thread pressing piece 3 close to the auxiliary blade 4 can be embedded into the thread pressing groove 423. Figure 10 Figure 11

[0059] Embodiment six

[0060] The embodiment is basically same as the structure and principle of the embodiment two, and the difference is that, as shown in the figure, the thread pressing piece 3 is slidingly connected to the moving blade 5 along the swinging direction of the moving blade 5, and as shown in the figure, the thread pressing piece 3 is slidingly connected to the moving blade 5 along the swinging direction of the moving blade 5. Figure 12 Further, a strip-shaped groove is arranged on the thread pressing piece 12, and a bolt is arranged in the strip-shaped groove to fixedly connect the thread pressing piece 12 to the auxiliary blade 4, so that the position of the thread pressing piece 12 can be adjusted, and then the length of the end of the thread pressing piece 12 close to the needle protruding from the end face of the thread cutting end 421 can be adjusted.

[0061] The specific embodiments described in the present document are only illustrative of the spirit of the present application. Those skilled in the art to which the present application belongs can make various modifications or supplements to the described specific embodiments or replace them with similar ways, but will not deviate from the spirit of the present application or exceed the scope defined by the appended claims. ​​​

[0062] Although the terms of 1, bed; 2, needle plate; 21, needle hole; 3, press line piece; 31, press line end; 32, push inclined surface; 33, connecting hole; 4, auxiliary knife; 41, straight section; 42, arc section; 421, line cutting end; 422, auxiliary knife edge; 5, moving knife; 51, line hooking groove; 52, moving knife edge; 53, mounting hole; 54, limiting protrusion; 6, knife seat; 7, avoidance gap; 8, reset spring; 9, hinged piece; 10, rotating shuttle; 11, needle are used more in this paper, but the possibility of using other terms is not excluded. The use of these terms is only to facilitate the description and explanation of the essence of the utility model; it is contrary to the spirit of the utility model to interpret them as any kind of additional limitation.

Claims

1. A thread trimming structure of a sewing machine, the sewing machine comprising a machine base (1) and a needle plate (2) having a drop needle hole (21), the thread trimming structure comprising a presser foot (3), an auxiliary cutter (4) arranged on the machine base (1), and a movable cutter (5) located below the needle plate (2) and capable of swinging up and down about a rotating shuttle shaft of the sewing machine, the auxiliary cutter (4) having a thread trimming end (421) with an auxiliary cutter edge (422), the movable cutter (5) having a thread hooking groove (51) and an upper edge of the thread hooking groove (51) being formed with a movable cutter edge (52), the thread hooking groove (51) being capable of being vertically aligned with the drop needle hole (21) when the movable cutter (5) swings upward, and the movable cutter edge (52) being capable of engaging with the auxiliary cutter edge (422) when the movable cutter (5) swings downward, characterized in that, The pressing wire piece (3) is movably connected to the upper side of the moving cutter (5), and the moving cutter (5) is further provided with a reset spring (8) acting on the pressing wire piece (3), and the pressing wire piece (3) can move against the elastic force of the reset spring (8) in the direction away from the auxiliary cutter (4) under external force, and the shearing wire end (421) of the auxiliary cutter (4) can abut against the pressing wire piece (3) when the auxiliary cutter blade edge (422) engages with the moving cutter blade edge (52).

2. The thread trimming structure of the sewing machine according to claim 1, characterized by, The auxiliary cutter (4) is fixedly connected to the machine base (1).

3. The thread trimming structure of the sewing machine according to claim 1, characterized by, The shearing wire structure further comprises a cutter holder (6) provided on the machine base (1) and capable of swinging around the rotating hook shaft of the sewing machine, and the auxiliary cutter (4) is fixedly connected to the cutter holder (6), and the cutter holder (6) is connected with a driving source capable of driving the swinging of the cutter holder (6).

4. The thread trimming structure of the sewing machine according to claim 1 or 2 or 3, characterized in that, The pressing wire piece (3) is in the shape of a strip, one end of the pressing wire piece (3) is hingedly connected to the moving cutter (5), and the other end is a pressing wire end (31), the moving cutter (5) is provided with a limiting protrusion (54), and under the elastic force of the reset spring (8), the side edge of the side of the pressing wire piece (3) close to the auxiliary cutter (4) can abut against the limiting protrusion (54), and the lower side of the side of the pressing wire end (31) close to the auxiliary cutter (4) is located above the moving cutter blade edge (52).

5. The thread trimming structure of the sewing machine according to claim 4, wherein The lower side of the side of the pressing wire end (31) close to the auxiliary cutter (4) has an avoiding gap (7) with the upper side of the moving cutter (5), and when the moving cutter (5) swings downward, the pressing wire end (31) of the auxiliary cutter (4) can enter the avoiding gap (7) and make the upper side of the shearing wire end (421) abut against the lower side of the pressing wire end (31).

6. The thread trimming structure of the sewing machine according to claim 5, wherein The lower side of the side of the pressing wire end (31) close to the auxiliary cutter (4) is a pushing inclined surface (32), and the pushing inclined surface (32) gradually approaches the upper side of the moving cutter (5) from one end close to the auxiliary cutter (4) to the other end.

7. The thread trimming structure of the sewing machine according to claim 3, wherein The auxiliary cutter (4) is a strip-shaped metal piece bent to form, and the auxiliary cutter (4) comprises a flat section (41) arranged in parallel with the rotating hook shaft of the sewing machine and an arc-shaped section (42) protruding to the side relative to the flat section (41), the curvature of the arc-shaped section (42) matches the curvature of the upper surface of the moving cutter (5), one end of the flat section (41) is fixedly connected to the cutter holder (6), and the end of the arc-shaped section (42) away from the flat section (41) is the shearing wire end (421), and the lower edge of the end surface of the shearing wire end (421) forms the auxiliary cutter blade edge (422).

8. The thread trimming structure of the sewing machine according to claim 1 or 2, characterized by The pressing wire piece (3) is slidably connected to the moving cutter (5) along the swinging direction of the moving cutter (5).

9. The thread trimming structure of the sewing machine according to claim 3, wherein The shearing wire end (421) of the auxiliary cutter (4) has a pressing wire groove (423) penetrating the front and back surfaces of the auxiliary cutter (4) on the end surface, and when the moving cutter (5) swings downward, the side of the pressing wire piece (3) close to the auxiliary cutter (4) can be embedded in the pressing wire groove (423).

10. The thread trimming structure of the sewing machine according to claim 2, wherein The upper side of the auxiliary cutter (4) is further slidably connected with a wire guide piece (12), one end of the wire guide piece (12) close to the needle protrudes from the end surface of the shearing wire end (421) and has a wire guide groove (121) at the end.

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