Sewing machine and feed lifting mechanism thereof

Abstract

The utility model provides a feed lifting mechanism which comprises a feed rack, a feeding tooth fixed on the feed rack, a feed lifting shaft, a feed lifting left fork-shaped crank fixed at one end of the feed lifting shaft, a driving motor, a rotary driving source, a feed lifting right fork-shaped crank fixed at the other end of the feed lifting shaft, and a feed lifting eccentric wheel sleeved on the feed lifting shaft, the feed lifting eccentric wheel comprises a first shaft section and a second shaft section which are connected with each other, the first shaft section and the second shaft section are eccentrically arranged, and the first shaft section and the feed lifting shaft are coaxially arranged; the second shaft section is sleeved with a feed lifting right crank, a rotatable sliding block is arranged on the feed lifting right crank, and the sliding block is movably arranged in an open groove of the feed lifting right fork-shaped crank; the feed lifting right crank is connected with a rotary driving source, and the first shaft section is connected with a driving motor. The utility model further provides a sewing machine which comprises the feed lifting mechanism. According to the feed lifting mechanism, the height of the feeding teeth can be flexibly adjusted, the feeding track of the feeding teeth can be changed according to needs, and the feeding effect of the sewing machine is improved.

Description

Technical Field

[0001] The utility model relates to a tooth lifting mechanism and a sewing machine comprising the tooth lifting mechanism. Background Art

[0002] A sewing machine is a machine that sews materials together with sutures, which is equipped with an upper shaft, a tooth frame, a feed tooth, a feed mechanism connected between the upper shaft and the front end of the tooth frame, and a tooth lifting mechanism connected between the upper shaft and the rear end of the tooth frame. When the sewing machine is working, the upper shaft drives the feed shaft and the tooth lifting shaft to rotate, the feed mechanism drives the tooth frame and the feed tooth to make a forward and backward reciprocating motion parallel to the X-axis direction, and the tooth lifting mechanism drives the tooth frame and the feed tooth to make an up and down reciprocating motion parallel to the Y-axis direction, and finally the feed tooth moves as follows Figure 1 The motion track shown is an elliptical compound motion, driving the fabric forward to complete the feeding action. However, when the feed dog just exposes the upper plane of the needle plate or is about to fall into the plane of the needle plate, the feeding along the front and rear directions is still in progress. At this time, the feed dog exposes less part of the needle plate, making it difficult to act on the sewing material and effectively feed the sewing material. The area that can truly achieve effective feeding is only in the middle of the ellipse, that is, when the feed dog exposes more part of the needle plate, this will cause low feeding efficiency and produce the problem of weak feeding that users often report. Utility Model Content

[0003] In view of the above-mentioned defects, the purpose of the utility model is to provide a feeding dog lifting mechanism capable of adjusting the height of the feeding dog.

[0004] The utility model provides a tooth-lifting mechanism, including a tooth rack, a feed tooth fixed on the tooth rack, a tooth-lifting shaft, a left tooth-lifting fork crank fixed at one end of the tooth-lifting shaft, and a tooth-lifting slider hinged to one end of the tooth rack, the tooth-lifting slider being movably arranged in a slot of the left tooth-lifting fork crank, and also including a driving motor, a rotating driving source, a right tooth-lifting fork crank fixed at the other end of the tooth-lifting shaft, and a tooth-lifting eccentric wheel sleeved on the tooth-lifting shaft, the tooth-lifting eccentric wheel including a first shaft segment and a second shaft segment connected to each other, the first shaft segment and the second shaft segment being eccentrically arranged, and the first shaft segment and the tooth-lifting shaft being coaxially arranged; a right tooth-lifting crank is sleeved on the second shaft segment, a rotatable slider is arranged on the right tooth-lifting crank, and the slider is movably arranged in the slot of the right tooth-lifting fork crank; the right tooth-lifting crank is connected to the rotating driving source, and the first shaft segment is connected to the driving motor.

[0005] Preferably, a tooth-lifting driving cam is provided on the output shaft of the driving motor, and the outer periphery of the tooth-lifting driving cam has a tooth height adjustment section and a lower supply section that are independent of each other; the first shaft section is connected to the tooth-lifting driving cam through a tooth-lifting transmission assembly, and the tooth-lifting transmission assembly includes a rotatable tooth-lifting roller, and the tooth-lifting roller abuts against the outer periphery of the tooth-lifting driving cam; when the tooth height adjustment section abuts against the tooth-lifting roller, the height of the feed tooth changes with the rotation of the output shaft; when the lower supply section abuts against the tooth-lifting roller, the height of the feed tooth is not greater than zero.

[0006] Preferably, the tooth lifting transmission assembly includes a driving shaft, a first end of which is fixed with an adjusting right crank, and the adjusting right crank is hinged to the first shaft section through a first connecting rod; a second end of the driving shaft is fixed with a driving adjusting left crank, and the driving adjusting left crank is connected to the tooth lifting roller.

[0007] Preferably, the drive adjustment left crank is hinged to one end of the adjustment drive lever through a second connecting rod, the other end of the adjustment drive lever is hinged to the mounting bracket of the drive motor, and the tooth lifting roller is rotatably arranged on the adjustment drive lever.

[0008] Preferably, the tooth lifting transmission assembly also includes a fixedly arranged left sleeve of the driving shaft, which is arranged on the outside of the second end of the driving shaft, one end of which abuts against the driving adjustment left crank, and the other end abuts against the shaft retaining ring arranged on the driving shaft.

[0009] Preferably, a torsion spring is sleeved on the first shaft segment, one end of the torsion spring is fixed, and the other end is connected to the first shaft segment.

[0010] Preferably, a retaining ring is fixedly mounted on the tooth lifting shaft, the retaining ring abuts against the first shaft section, and the tooth lifting right crank abuts against the tooth lifting right fork crank.

[0011] Preferably, the tooth lifting right crank includes a first connecting portion and a second connecting portion, the first connecting portion is connected to a rotation driving source, and the slider is rotatably disposed on the second connecting portion.

[0012] Preferably, it also includes an upper shaft rotatably arranged in the sewing machine, a feeding eccentric wheel is provided on the upper shaft, the tooth lifting right crank is hinged to the feeding eccentric wheel through a tooth lifting connecting rod, and the upper shaft rotates under the drive of the rotating drive source.

[0013] The utility model also provides a sewing machine, comprising the above-mentioned tooth lifting mechanism.

[0014] The tooth lifting mechanism provided by the utility model can flexibly adjust the height of the feed tooth through the structure of the tooth lifting eccentric wheel and the double crank, and can change the feeding track of the feed tooth as needed, thereby improving the feeding effect of the sewing machine. In addition, the sewing machine of the utility model can realize multiple functions such as automatic bird nest removal, automatic thread cutting, adjusting the tooth lifting height, changing the feeding track, etc. through one motor, which saves the internal installation space of the sewing machine and reduces the production cost of the sewing machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the feeding track of an existing sewing machine;

[0016] Figure 2 It is a three-dimensional diagram of the sewing machine of the utility model;

[0017] Figure 3 is a schematic diagram of the connection structure between the drive motor and the tooth lifting transmission assembly in the first embodiment;

[0018] Figure 4 This is a schematic diagram of the structure of the tooth lifting eccentric wheel;

[0019] Figure 5 This is a schematic diagram of the structure of the right crank for lifting the teeth;

[0020] Figure 6 This is a schematic diagram of the structure of the tooth lifting drive cam;

[0021] Figure 7 It is a schematic diagram of the position of the feed dog relative to the needle plate when the tooth lifting roller abuts against the lower feed section of the tooth lifting drive cam;

[0022] Figure 8 It is a schematic diagram of the feeding track after adjustment by the tooth lifting mechanism of the utility model;

[0023] Fig. 9 is a schematic diagram of the structure of the driving motor and the tooth lifting transmission assembly in the second embodiment;

[0024] Fig.10 It is a schematic diagram of the internal structure of the sewing machine of the utility model;

[0025] Fig.11 and Fig.12 Schematic diagram of the connection structure between the driving motor and the thread trimming transmission mechanism from different viewing angles;

[0026] Fig.13 This is a schematic diagram of the position of the moving knife when starting to sew;

[0027] Fig.14 This is a schematic diagram of the relative positions of the moving knife and the pressing plate after the first needle;

[0028] Fig.15 This is a schematic diagram of the position of the moving knife when cutting the thread;

[0029] Fig.16 It is a schematic diagram of the structure of the moving knife;

[0030] Fig.17 It is a schematic diagram of the relative positions of the thread trimming drive member and the thread trimming fork crank when the tooth lifting roller abuts against the tooth height adjustment section of the tooth lifting drive cam.

[0031] Component number description:

[0032] 1. Chassis

[0033] 2 Bottom plate

[0034] 21 Needle plate

[0035] 3 Upper axis

[0036] 4 Tooth lifting axis

[0037] 41 Feed eccentric wheel

[0038] 42 tooth lifting connecting rod

[0039] 43 tooth lift right fork crank

[0040] 44 Sliders

[0041] 45 Tooth lift right crank

[0042] 451 First connection

[0043] 452 Second connection

[0044] 46 Eccentric wheel for lifting teeth

[0045] 461 First shaft section

[0046] 462 Second shaft section

[0047] 47 Torsion spring

[0048] 48 Retaining ring

[0049] 5 Feed axis

[0050] 6. Drive Motor

[0051] 61 Output shaft

[0052] 62 Mounting bracket

[0053] 71 lifting gear drive cam

[0054] 72 tooth lifting roller

[0055] 721 Drive adjustment lever

[0056] 722 Second connecting rod

[0057] 731 Drive adjustment left crank

[0058] 732 Drive adjustment right crank

[0059] 74 Drive shaft

[0060] 751 drive shaft left sleeve

[0061] 752 drive shaft right sleeve

[0062] 76 First connecting rod

[0063] 81 Thread trimmer drive

[0064] 811 Trimming roller

[0065] 82 Trimming fork crank

[0066] 83 Stop bracket

[0067] 831 Stop pad

[0068] 84 Reset torsion spring

[0069] 85 Trimming crank

[0070] 86 Trimming rod

[0071] 87 Tool holder pressure plate

[0072] 88 Thread trimmer

[0073] 881 Thread trimmer sleeve

[0074] 91 Lifting left fork crank

[0075] 92 tooth frame

[0076] 93 Platen

[0077] 94 Knife

[0078] 941 Pinhole

[0079] 942 Moving blade edge

[0080] 943 Moving blade tip

[0081] 944 Line Drawing Department

[0082] 95 Fixed Knife

[0083] 96 Thread nozzle

[0084] 97 Moving tool holder

[0085] 98 Needle

[0086] 99 Tooth frame

[0087] 991 Feed dog DETAILED DESCRIPTION

[0088] The following is a further detailed description of the specific implementations of the present invention in conjunction with the accompanying drawings. These implementations are only used to illustrate the present invention, but not to limit the present invention.

[0089] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0090] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0091] Figure 2 The utility model sewing machine is shown in a three-dimensional diagram. In the following description, Figure 2 The attached figure in the figure is used as a reference for the direction. Figure 2 In the figure, the length direction of the base plate 2 is defined as the left-right direction, and the needle plate 21 is located on the left side of the base plate 2; the width direction of the base plate 2 is defined as the front-back direction, and the feed shaft 5 is located in front of the tooth-lifting shaft 4; the height direction of the base plate 2 is defined as the up-down direction, and the upper shaft 3 is located above the tooth-lifting shaft 4.

[0092] like Figure 2-5As shown, the utility model provides a tooth lifting mechanism and a sewing machine including the tooth lifting mechanism. The sewing machine includes a fixed base plate 2 and a casing 1 arranged on the base plate 2, a needle plate 21 fixed to the left side of the upper surface of the base plate 2, and an upper shaft 3 rotatably arranged in the casing 1. The tooth lifting mechanism includes a tooth rack 99, a feed tooth 991 fixed on the tooth rack 99, a tooth lifting shaft 4 extending in the left and right directions, a tooth lifting left fork-shaped crank 91 fixed at the left end of the tooth lifting shaft 4, and a tooth lifting slider hinged to the rear end of the tooth rack 99, and the tooth lifting slider is movably arranged in the slot of the tooth lifting left fork-shaped crank 91. The tooth lifting mechanism also includes a driving motor 6, a rotating driving source, a tooth lifting right fork-shaped crank 43 fixed at the right end of the tooth lifting shaft 4, and a tooth lifting eccentric wheel 46 sleeved on the tooth lifting shaft 4. The driving motor 6 is fixedly mounted on the base plate 2 through a mounting bracket 62. As shown Figure 4 As shown, the tooth lifting eccentric wheel 46 includes a first shaft section 461 and a second shaft section 462 connected to each other. The first shaft section 461 and the second shaft section 462 are eccentrically arranged, and the first shaft section 461 is coaxially arranged with the tooth lifting shaft 4. The first shaft section 461 is connected to the driving motor 6. The second shaft section 462 is sleeved with a tooth lifting right crank 45. Figure 5 As shown, the right crank 45 for lifting teeth includes a first connection portion 451 and a second connection portion 452, both of which extend along the radial direction of the right crank 45 for lifting teeth, and there is an angle between the first connection portion 451 and the second connection portion 452. The first connection portion 451 is connected to the rotation drive source, and a rotatable slider 44 is provided on the second connection portion 452. The slider 44 is movably arranged in the slot of the right fork-shaped crank 43 for lifting teeth.

[0093] like Figure 3 As shown, a retaining ring 48 is also fixedly mounted on the tooth lifting shaft 4, and the retaining ring 48 abuts against the left end of the first shaft section 461. At the same time, the tooth lifting right crank 45 abuts against the tooth lifting right fork crank 43. The retaining ring 48 and the tooth lifting right crank 45 work together to limit the left-right displacement of the tooth lifting eccentric wheel 46 on the tooth lifting shaft 4, but will not limit the rotation of the tooth lifting eccentric wheel 46.

[0094] The rotary drive source is another motor independent of the drive motor 6, which can be directly connected to the first connecting portion 451 to directly drive the tooth lifting right crank 45 to swing around the second shaft segment 462; it can also be connected to the upper shaft 3, on which a feeding eccentric wheel 41 is provided, and the tooth lifting right crank 45 is hinged to the feeding eccentric wheel 41 through a tooth lifting connecting rod 42. The upper shaft 3 rotates under the drive of the rotary drive source, driving the feeding eccentric wheel 41 to rotate, and then driving the tooth lifting right crank 45 to swing around the second shaft segment 462 through the tooth lifting connecting rod 42.

[0095] When the driving motor 6 is not working, the rotating driving source is working, driving the right crank 45 for lifting the tooth to swing around the second shaft section 462 as the axis, and driving the right fork-shaped crank 43 for lifting the tooth to swing through the slider 44. Since the right fork-shaped crank 43 for lifting the tooth is fixed to the right end of the tooth-lifting shaft 4, the tooth-lifting shaft 4 swings accordingly, and finally drives the left fork-shaped crank 91 for lifting the tooth to swing up and down, and the tooth rack 99 and the feeding tooth 991 make up and down reciprocating motion to realize the tooth lifting action.

[0096] When the driving motor 6 is working, it drives the tooth-lifting eccentric wheel 46 to rotate around the axial direction of the tooth-lifting shaft 4, and the tooth-lifting right crank 45 mounted thereon rotates accordingly, and the angle between the tooth-lifting right crank 45 and the tooth-lifting shaft 4 and the tooth-lifting right fork crank 43 changes accordingly, thereby changing the tooth-lifting height of the feed tooth 991.

[0097] Furthermore, if Figure 3 and Figure 6 As shown, a tooth lifting driving cam 71 is provided on the output shaft 61 of the driving motor 6, and the outer periphery of the tooth lifting driving cam 71 has a mutually independent tooth height adjustment section and a lower supply section. Specifically, the outer periphery of the tooth lifting driving cam 71 is pear-shaped with one end small and the other end large, and the lower supply section is arranged at the small head, which is far away from the rotation center of the tooth lifting driving cam 71; the tooth height adjustment section is arranged between the small head and the large head, and is a variable diameter section. The first shaft section 461 is connected to the tooth lifting driving cam 71 through a tooth lifting transmission assembly, and the tooth lifting transmission assembly includes a rotatable tooth lifting roller 72. A torsion spring 47 is also sleeved on the first shaft section 461, one end of the torsion spring 47 rests on the base plate 2, and the other end is connected to the first shaft section 461. The tooth lifting eccentric wheel 46 transmits the force of the torsion spring 47 through the tooth lifting transmission assembly, so that the tooth lifting roller 72 always rests on the outer periphery of the tooth lifting driving cam 71.

[0098] In the first embodiment, the tooth lifting transmission assembly includes a drive shaft 74, which extends in the left-right direction. The right end (i.e., the first end) of the drive shaft 74 is arranged in the right drive shaft sleeve 752 and fixedly connected to the right drive adjustment crank 732, which is hinged to the first shaft section 461 through the first connecting rod 76; the left end (i.e., the second end) of the drive shaft 74 is arranged in the left drive shaft sleeve 751 and fixedly connected to the left drive adjustment crank 731, which is hinged to one end of the adjustment driving lever 721 through the second connecting rod 722. The other end of the adjustment driving lever 721 is hinged to the mounting bracket 62 of the drive motor 6, and the tooth lifting roller 72 is rotatably arranged on the adjustment driving lever 721. The right drive shaft sleeve 752 and the left drive shaft sleeve 751 are both fixed on the base plate 2. The left end of the left drive shaft sleeve 751 abuts against the left drive adjustment crank 731, and the right end abuts against the shaft retaining ring set on the drive shaft 74. This setting can prevent the drive shaft 74 from moving left and right, but does not affect its rotational movement.

[0099] When the tooth height adjustment section contacts the tooth lifting roller 72, the drive motor 6 starts working, and the tooth lifting roller 72 moves along the tooth height adjustment section with a variable diameter. The tooth lifting transmission assembly causes the tooth lifting eccentric wheel 46 to rotate around the axis of the tooth lifting shaft 4, and the tooth lifting right crank 45 sleeved thereon rotates accordingly. The angle of the tooth lifting right crank 45 relative to the tooth lifting shaft 4 and the tooth lifting right fork crank 43 changes accordingly, thereby changing the tooth lifting height of the feed tooth 991. Therefore, the drive motor 6 can realize stepless adjustment of the height of the feed tooth 991. Figure 7 As shown, when the lower feeding section contacts the tooth lifting roller 72, the driving motor 6 works, and the height of the feed tooth 991 is not greater than zero, that is, the height of the feed tooth 991 is always less than the height of the upper plane of the needle plate 21, and the feed tooth 991 will not emerge from the needle plate 21, so that the sewing machine has a lower feeding function. With the existing presser foot lifting function of the sewing machine, the operator can place the sewing material flatly on the needle plate 21, avoiding the problem that the feed tooth 991 is hung on the sewing material and causes the sewing material to be placed unevenly and unsmoothly.

[0100] The sewing machine with the above-mentioned tooth lifting mechanism can adjust the height of the feed dog 991 in real time during the sewing process, realize the functions of sewing trajectory change, stitch length compensation, etc., and thus achieve better sewing effect. The specific description is as follows:

[0101] Combination Fig.10 It can be known that the sewing machine provided by the utility model also includes a feeding mechanism, which includes a feeding shaft 5 rotatably arranged in the bottom plate 2 and a tooth frame seat 92 arranged at the left end of the feeding shaft 5, and the tooth frame seat 92 and the front end of the tooth frame 99 are hinged. The feeding shaft 5 extends in the left and right directions. When the sewing machine is working, the upper shaft 3 drives the feeding shaft 5 and the tooth lifting shaft 4 to rotate, and the feeding mechanism drives the tooth frame 99 and the feeding tooth 991 to make a forward and backward reciprocating motion parallel to the X-axis direction, and the tooth lifting mechanism drives the tooth frame 99 and the feeding tooth 991 to make an up and down reciprocating motion parallel to the Y-axis direction, and finally the feed tooth 991 does as follows Figure 1 The motion track shown is a compound motion in the shape of an ellipse, driving the fabric forward to complete the feeding action. However, when the feed tooth 991 just exposes the upper plane of the needle plate or is about to fall into the upper plane of the needle plate, the feeding along the front-back direction is still in progress. At this time, the feed tooth 991 exposes less part of the needle plate 21, making it difficult to act on the sewing material and effectively feed the sewing material. The effective feeding interval is only in the middle of the ellipse, that is, when the feed tooth exposes more part of the needle plate 21, this will cause low feeding efficiency and produce the problem of weak feeding often reported by users.

[0102] The sewing machine of the utility model can be combined with a thickness detection sensor or an electronic control to set mode parameters. In the process of sewing specific sewing materials (such as thick materials), when the feed dog 991 just exposes the needle plate 21, the output shaft 61 of the drive motor 6 is rotated through the electronic control to make the tooth height adjustment section abut against the tooth lifting roller 72, and the feed dog 991 is raised in real time for compensation. That is, when feeding forward (negative direction of the x-axis), the feed dog 991 is raised upward (positive direction of the y-axis) for compensation, so that the feed dog 991 is kept close to the high point of the trajectory for forward feeding, thereby avoiding low feeding efficiency caused by insufficient height of the feed dog 991 in the early stage of feeding. Similarly, the same compensatory adjustment is performed when feeding is about to end. The feeding trajectory is composed of Figure 1 The elliptical trajectory shown becomes Figure 8 The nearly rectangular trajectory shown helps to maximize the feeding efficiency of the feed dog 991 above the needle plate 21, making the feeding more powerful and smooth.

[0103] It can be seen that the tooth lifting mechanism provided by the utility model can flexibly adjust the height of the feed dog and fine-tune the feeding trajectory of the feed dog 991, so that it changes from a quasi-elliptical trajectory to a nearly rectangular trajectory, further improving the feeding effect of the sewing machine.

[0104] like Fig. 9 As shown, the difference between the tooth lifting transmission assembly in the second embodiment and the tooth lifting transmission assembly in the first embodiment is that the driving adjustment lever 721 and the second connecting rod 722 are cancelled, and the tooth lifting roller 72 is rotatably arranged on the driving adjustment left crank 731. It can realize the same feed dog height adjustment function as in the first embodiment.

[0105] Furthermore, if Figure 6 and Fig.10 As shown, the sewing machine provided by the utility model also includes a thread trimming mechanism. The output shaft 61 of the driving motor 6 is respectively fixed with a tooth lifting driving cam 71 and a thread trimming driving member 81, and the tooth lifting driving cam 71 and the thread trimming driving member 81 rotate synchronously with the output shaft 61. The driving motor 6 can be as follows Fig.10 The single-output shaft motor shown can also be a double-output shaft motor at both ends. When the latter is adopted, the tooth lifting drive cam 71 and the thread cutting drive member 81 can be respectively arranged on the output shafts on different sides, thereby changing the internal structure distribution of the sewing machine. The thread cutting drive member 81 is connected to the thread cutting mechanism through the thread cutting transmission assembly. The outer periphery of the tooth lifting drive cam 71 also has a thread cutting anti-bird nest section that is independent of the tooth height adjustment section and the lower supply section. The thread cutting anti-bird nest section is specifically arranged at the large head of the tooth lifting drive cam 71, which is concentrically arranged with the rotation center of the tooth lifting drive cam 71 and is an equal diameter section.

[0106] When the anti-bird nest section of the thread trimmer abuts against the tooth lifting roller 72, the drive motor 6 works, and the tooth lifting roller 72 does not move along the anti-bird nest section of the thread trimmer of equal diameter, so the height of the feed tooth 991 remains unchanged and is a set value, and there is power transmission between the thread trimmer drive 81 and the thread trimmer transmission assembly. The drive motor 6 can drive the thread trimmer mechanism to cut off the upper thread end when the sewing machine starts sewing to achieve the anti-bird nest effect, or cut off the suture when sewing is completed to complete the thread trimming. When the tooth height adjustment section or the lower feed section abuts against the tooth lifting roller 72, there is no power transmission between the thread trimmer drive 81 and the thread trimmer transmission assembly, and the thread trimmer mechanism remains stationary.

[0107] Specifically, Figure 10-12 As shown, the wire cutting drive member 81 is a crank, and a rotatable wire cutting roller 811 is provided at the end thereof. The wire cutting transmission assembly includes a wire cutting shaft 88 rotatably arranged in the bottom plate 2, a wire cutting fork crank 82 fixedly connected to the right end of the wire cutting shaft 88, a wire cutting crank 85 fixedly connected to the left end of the wire cutting shaft 88, and a wire cutting connecting rod 86 hinged to the wire cutting crank 85, and the wire cutting connecting rod 86 is connected to the wire cutting mechanism. When the wire cutting anti-bird nest section abuts against the tooth lifting roller 72, the wire cutting roller 811 contacts and cooperates with the slot of the wire cutting fork crank 82, and power is transmitted between the two. Fig.17 As shown, when the tooth height adjustment section or the lower supply section abuts against the tooth lifting roller 72, the thread cutting roller 811 is separated from the thread cutting fork crank 82, and no power is transmitted between the two.

[0108] Furthermore, the thread trimming mechanism includes a movable knife holder 97 rotatably arranged in the bottom plate 2, a movable knife 94 fixed on the movable knife holder 97, a fixed knife 95 fixed on the bottom plate 2, a pressure plate 93 and a thread end suction nozzle 96, the fixed knife 95 and the pressure plate 93 are arranged above the movable knife 94 from bottom to top, and the movable knife holder 97 is hinged with the thread trimming connecting rod 86. In a specific embodiment of the utility model, the movable knife holder 97 and the knife holder pressure plate 87 are sequentially sleeved on the left end of the lower shaft front sleeve, the lower shaft front sleeve is fixedly mounted on the bottom plate 2, and the knife holder pressure plate 87 limits the movable knife holder 97 to the left and right to prevent the movable knife holder 97 from moving in the left and right directions, but does not restrict its rotation. The thread trimming transmission assembly also includes a thread trimming shaft sleeve 881 sleeved on the outside of the thread trimming shaft 88, and the thread trimming shaft sleeve 881 is fixedly mounted on the bottom plate 2. The trimming fork crank 82 abuts against the right end face of the trimming sleeve 881, and the trimming crank 85 abuts against the left end face of the trimming sleeve 881, and the two work together to limit the left and right movement of the trimming shaft 88 inside the trimming sleeve 881. The trimming transmission assembly also includes a reset torsion spring 84 sleeved on the trimming sleeve 881, a stop bracket 83 fixed on the bottom plate 2, and a stop pad 831 arranged on the stop bracket 83, one end of the reset torsion spring 84 abuts against the bottom plate 2, and the other end is connected to the trimming crank 85. When the tooth height adjustment section or the lower supply section abuts against the tooth lifting roller 72, the trimming roller 811 is separated from the trimming fork crank 82, and there is no power transmission between the two. At this time, the trimming crank 85 is always abutted against the stop pad 831 under the action of the reset torsion spring 84, and cannot swing freely, so the trimming mechanism remains stationary and does not produce any movement.

[0109] like Figure 14-16 As shown, the movable knife 94 is provided with a movable knife tip 943, a needle drop hole 941 and a thread hooking portion 944, the needle drop hole 941 allows the needle 98 to pass through, and a movable knife edge 942 is provided on the surface of the movable knife 94 facing the fixed knife 95, the needle drop hole 941 and the thread hooking portion 944 are distributed on the rear side of the movable knife edge 942, and the movable knife tip 943 is distributed on the front side of the movable knife edge 942.

[0110] When the anti-bird nest section of the wire trimming device abuts against the tooth-lifting roller 72, the wire trimming roller 811 contacts and cooperates with the slot of the wire trimming fork crank 82, and power is transmitted between the two. The specific process of realizing the anti-bird nest and wire trimming functions is as follows:

[0111] like Fig.13As shown, when sewing, the needle 98 moves downward, and the driving motor 6 acts on the thread trimming fork crank 82 through the thread trimming roller 811, driving the movable knife 94 to rotate forward away from the fixed knife 95, so that the needle drop hole 941 is located directly below the needle 98, and the needle 98 passes through the needle drop hole 941 and completes the thread hooking through the rotary shuttle. When the needle 98 rises back to the vicinity of the needle plate 21, the driving motor 6 drives the movable knife 94 to rotate toward the rear of the fixed knife 95, and the needle drop hole 941 drives the upper thread head brought by the first needle to rotate backward toward the fixed knife 95, and the movable knife 94 stops as shown in FIG. Fig.14 The upper thread end is located on the upper surface of the movable knife 94, and the pressure plate 93 works together to clamp the upper thread end brought by the needle drop hole 941. The movable knife edge 942 and the fixed knife edge of the fixed knife 95 are not engaged, and the upper thread end has not been cut off. The sewing machine continues to sew the set number of stitches. During this process, the movable knife edge 942 and the fixed knife edge remain in a non-engaged state, and the upper thread end is always clamped on the upper surface of the movable knife 94, which can effectively prevent the thread from coming off. Then the driving motor 6 drives the movable knife 94 to continue to rotate backward until it reaches the position shown in the figure. Fig.15 As shown, the movable blade edge 942 engages with the fixed blade edge to cut off the surface thread ends, achieving a less bird's nest effect.

[0112] When the sewing machine needs to trim the thread at the end, the driving motor 6 drives the movable knife 94 to rotate toward the front of the needle 98, and after the movable knife tip 943 completes the line separation, the movable knife 94 is driven to rotate toward the rear away from the needle 98. During this process, the thread hooking part 944 rotates with the upper thread and the lower thread toward the fixed knife 95. After the movable knife 94 rotates to the thread trimming position, the movable knife edge 942 engages with the fixed knife edge to cut the upper thread and the lower thread, thereby realizing automatic thread trimming at the end of sewing.

[0113] As can be seen from the above, the sewing machine provided by the utility model can realize multiple functions such as preventing bird nests, thread trimming, adjusting feed dog height, lower feeding, and track changing with one driving motor, thereby reducing the number of motors in the sewing machine, simplifying the overall structure of the sewing machine, and reducing costs.

[0114] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principle of the present invention. These improvements and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A tooth lifting mechanism, comprising a tooth frame, a feed tooth fixed on the tooth frame, a tooth lifting shaft, a tooth lifting left fork crank fixed at one end of the tooth lifting shaft, and a tooth lifting slider hinged to one end of the tooth frame, wherein the tooth lifting slider is movably arranged in a slot of the tooth lifting left fork crank, characterized in that: It also includes a driving motor, a rotating driving source, a right tooth-lifting fork-shaped crank fixed to the other end of the tooth-lifting shaft, and a tooth-lifting eccentric wheel sleeved on the tooth-lifting shaft, the tooth-lifting eccentric wheel including a first shaft segment and a second shaft segment connected to each other, the first shaft segment and the second shaft segment being eccentrically arranged, and the first shaft segment being coaxially arranged with the tooth-lifting shaft; a right tooth-lifting crank is sleeved on the second shaft segment, a rotatable slider is provided on the right tooth-lifting crank, and the slider is movably arranged in the slot of the right tooth-lifting fork-shaped crank; the right tooth-lifting crank is connected to the rotating driving source, and the first shaft segment is connected to the driving motor.

2. The tooth lifting mechanism according to claim 1, characterized in that: The output shaft of the driving motor is provided with a tooth lifting driving cam, and the outer periphery of the tooth lifting driving cam has a tooth height adjustment section and a lower supply section which are independent of each other; the first shaft section is connected to the tooth lifting driving cam through a tooth lifting transmission assembly, and the tooth lifting transmission assembly includes a rotatable tooth lifting roller, and the tooth lifting roller abuts against the outer periphery of the tooth lifting driving cam; When the tooth height adjustment section abuts against the tooth lifting roller, the height of the feed tooth changes with the rotation of the output shaft; When the lower feeding section abuts against the tooth-lifting roller, the height of the feeding tooth is not greater than zero.

3. The tooth lifting mechanism according to claim 2, characterized in that: The tooth lifting transmission assembly includes a driving shaft, a first end of which is fixed with an adjusting right crank, and the adjusting right crank is hinged to the first shaft section through a first connecting rod; a second end of the driving shaft is fixed with a driving adjusting left crank, and the driving adjusting left crank is connected to the tooth lifting roller.

4. The tooth lifting mechanism according to claim 3, characterized in that: The driving adjustment left crank is hinged to one end of the adjusting driving lever through a second connecting rod, the other end of the adjusting driving lever is hinged to the mounting bracket of the driving motor, and the tooth lifting roller is rotatably arranged on the adjusting driving lever.

5. The tooth lifting mechanism according to claim 3, characterized in that: The tooth lifting transmission assembly also includes a fixedly arranged left drive shaft sleeve, which is arranged on the outside of the second end of the drive shaft, one end of which abuts against the drive adjustment left crank, and the other end abuts against a shaft retaining ring arranged on the drive shaft.

6. The tooth lifting mechanism according to claim 2, characterized in that: A torsion spring is sleeved on the first shaft segment, one end of the torsion spring is fixed, and the other end is connected to the first shaft segment.

7. The tooth lifting mechanism according to claim 1, characterized in that: A retaining ring is also fixedly mounted on the tooth lifting shaft, the retaining ring is in contact with the first shaft section, and the tooth lifting right crank is in contact with the tooth lifting right fork crank.

8. The tooth lifting mechanism according to claim 1, characterized in that: The tooth lifting right crank comprises a first connecting portion and a second connecting portion, the first connecting portion is connected to a rotation driving source, and the slider is rotatably disposed on the second connecting portion.

9. The tooth lifting mechanism according to claim 1, characterized in that: It also includes an upper shaft rotatably arranged in the sewing machine, on which a feeding eccentric wheel is arranged, and the tooth lifting right crank is hinged to the feeding eccentric wheel through a tooth lifting connecting rod, and the upper shaft rotates under the drive of the rotating driving source.

10. A sewing machine, characterized in that: It comprises a tooth lifting mechanism as described in any one of claims 1-9.

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