Sewing machine

Abstract

The utility model provides a sewing machine which comprises a feed dog frame, a feed dog installed on the feed dog frame, a feed dog lifting mechanism connected with one end of the feed dog frame, a thread trimming mechanism, a driving motor, a feed dog lifting transmission assembly and a thread trimming transmission assembly. The periphery of the feed lifting driving cam is provided with a thread cutting anti-nest section, a tooth height adjusting section and a feeding section which are mutually independent, the feed lifting transmission assembly comprises a rotatable feed lifting roller, the feed lifting roller abuts against the periphery of the feed lifting driving cam, and the feed lifting driving cam is connected with the feed lifting mechanism through the feed lifting transmission assembly; the thread trimming driving piece is connected with the thread trimming mechanism through a thread trimming transmission assembly. The automatic thread trimming device has the advantages that the multiple functions of automatically removing bird nests, automatically trimming threads, adjusting the height of the feed lifting teeth, changing the feeding track and the like are achieved through one motor, the internal installation space of the sewing machine is saved, and meanwhile the production and manufacturing cost of the sewing machine is reduced.

Description

Technical Field

[0001] The utility model relates to a sewing machine. Background Art

[0002] A sewing machine is a machine that sews sewing materials with sewing threads, and is equipped with an upper shaft, a tooth frame, a feed tooth, a thread trimming mechanism, 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 rotates under the drive of the main motor, and the upper shaft drives the tooth frame and the feed tooth to do back and forth reciprocating motion together through the feeding mechanism, and at the same time drives the tooth frame and the feed tooth to do up and down reciprocating motion together through the tooth lifting mechanism, realizing the composite motion of the feed tooth to do back and forth reciprocating motion and up and down reciprocating motion, and the motion trajectory is elliptical. After sewing is completed, the thread trimming mechanism automatically trims the thread and cuts the surface thread.

[0003] But existing sewing machines have the following defects:

[0004] 1. When the sewing machine starts to sew, the surface thread is often pulled out of the needle hole due to the force, causing sewing interruption. Therefore, the surface thread ends need to be left long when sewing. However, when the surface thread ends are too long, a bird's nest structure will be formed on the sewing material, affecting the beauty of the sewing material. Manual trimming is required before sewing is completed, which not only wastes man-hours but is also not easy to trim cleanly, and may even damage the existing stitches. Most of the various bird's nest removal devices launched on the market are installed above the sewing machine bottom plate, driven by electromagnets / cylinders, and cooperate with the knife on the presser foot to remove the bird's nest. However, such devices have problems such as affecting the operating space and a wide variety of presser feet. The cost of using an independent drive source to remove the bird's nest is too high, which increases the production cost of the sewing machine.

[0005] 2. The lifting height of the feed dog is a fixed value, which cannot meet the sewing requirements of sewing materials of different thicknesses and has poor adaptability. Utility Model Content

[0006] In view of the above problems, the purpose of the utility model is to provide a sewing machine which adopts a motor to realize automatic bird's nest removal, automatic thread trimming and adjustment of tooth lifting height.

[0007] The utility model provides a sewing machine, comprising a tooth frame, a feeding tooth installed on the tooth frame, a tooth lifting mechanism connected to one end of the tooth frame, a thread trimming mechanism, and also comprising a driving motor, a tooth lifting transmission assembly and a thread trimming transmission assembly, wherein a tooth lifting driving cam and a thread trimming driving member are respectively arranged on the output shaft of the driving motor, the outer periphery of the tooth lifting driving cam has mutually independent thread trimming anti-bird nest section, tooth height adjustment section and lower feed section, the tooth lifting transmission assembly comprises a rotatable tooth lifting roller, the tooth lifting roller abuts against the outer periphery of the tooth lifting driving cam, and the tooth lifting driving cam is connected to the tooth lifting mechanism through the tooth lifting transmission assembly; The wire cutting drive is connected to the wire cutting mechanism through the wire cutting transmission assembly; when the wire cutting anti-bird nest section is in contact with the tooth lifting roller, the height of the feed tooth remains unchanged, and there is power transmission between the wire cutting drive and the wire cutting transmission assembly, which can drive the wire cutting mechanism to operate; when the tooth height adjustment section is in contact with the tooth lifting roller, the height of the feed tooth changes with the rotation of the output shaft, and there is no power transmission between the wire cutting drive and the wire cutting transmission assembly; when the lower supply section is in contact with the tooth lifting roller, the height of the feed tooth is not greater than zero, and there is no power transmission between the wire cutting drive and the wire cutting transmission assembly.

[0008] Preferably, a rotatable wire cutting roller is provided at the end of the wire cutting drive member, and the wire cutting transmission assembly includes a wire cutting shaft rotatably arranged in the base plate, a wire cutting fork crank fixedly connected to one end of the wire cutting shaft, a wire cutting crank fixedly connected to the other end of the wire cutting shaft, and a wire cutting connecting rod hinged to the wire cutting crank, and the wire cutting connecting rod is connected to the wire cutting mechanism; when the wire cutting anti-bird nest section abuts against the tooth lifting roller, the wire cutting roller contacts and cooperates with the slot of the wire cutting fork crank; when the tooth height adjustment section or the lower supply section abuts against the tooth lifting roller, the wire cutting roller is separated from the wire cutting fork crank.

[0009] Preferably, the thread cutting mechanism includes a movable knife frame rotatably arranged on a base plate, a movable knife fixed on the movable knife frame, a fixed knife and a pressure plate fixed on the base plate, the fixed knife and the pressure plate are arranged above the movable knife in sequence from bottom to top, and the movable knife frame is hinged to the thread cutting connecting rod.

[0010] Preferably, the movable knife is provided with a movable knife tip, a needle drop hole and a thread hooking part, the needle drop hole allows the machine needle to pass through, and a movable knife blade is provided on the surface of the movable knife facing the fixed knife, the needle drop hole and the thread hooking part are distributed on one side of the movable knife blade, and the movable knife tip is distributed on the other side of the movable knife blade.

[0011] Preferably, the thread trimmer transmission assembly further comprises a reset torsion spring sleeved on the thread trimmer shaft, one end of the reset torsion spring abuts against the bottom plate, and the other end is connected to the thread trimmer crank.

[0012] Preferably, the thread trimmer transmission assembly further comprises a stop bracket fixed on the base plate, and a stop pad is provided on the stop bracket; when the tooth height adjustment section or the lower supply section abuts against the tooth lifting roller, the thread trimmer crank abuts against the stop pad.

[0013] Preferably, the wire cutting transmission assembly further comprises a wire cutting sleeve sleeved outside the wire cutting shaft, the wire cutting fork crank abuts against one end surface of the wire cutting sleeve, and the wire cutting crank abuts against the other end surface of the wire cutting sleeve.

[0014] Preferably, the driving motor is a single-shaft motor or a double-shaft motor at both ends.

[0015] Preferably, the tooth-lifting mechanism includes a tooth-lifting shaft rotatably arranged in the base plate, a tooth-lifting left fork-shaped crank fixed at one end of the tooth-lifting shaft, and a tooth-lifting slider hinged to one end of the tooth frame, and the tooth-lifting slider is movably arranged in the slot of the left fork-shaped crank for lifting the tooth; the tooth-lifting transmission assembly includes a rotational driving source, a tooth-lifting right fork-shaped 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 includes a first shaft segment and a second shaft segment connected to each other, the first shaft segment is eccentrically arranged with the second shaft segment, and the first shaft segment is coaxially arranged with the tooth-lifting shaft; the second shaft segment is sleeved with a tooth-lifting right crank, and the right tooth-lifting crank is provided with a rotatable slider, and the slider is movably arranged in the slot of the right fork-shaped crank for lifting the tooth; the tooth-lifting right crank is connected to the rotational driving source, and the first shaft segment is connected to the tooth-lifting roller.

[0016] Preferably, the tooth lifting transmission assembly also 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.

[0017] The utility model is beneficial in that it uses one motor to realize multiple functions such as automatic bird's nest removal, automatic thread cutting, adjustment of tooth lifting height, change of feeding trajectory, etc., which saves the internal installation space of the sewing machine and reduces the production cost of the sewing machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a three-dimensional diagram of the sewing machine of the utility model;

[0019] Figure 2 It is a schematic diagram of the internal structure of the sewing machine of the utility model;

[0020] Figure 3 This is a schematic diagram of the structure of the tooth lifting drive cam;

[0021] Figure 4It is a schematic diagram of the conventional feeding trajectory;

[0022] Figure 5 It is a schematic diagram of the feeding track after the track change;

[0023] Figure 6 and Figure 7 Schematic diagram of the connection structure between the drive motor and the thread trimmer transmission assembly from different viewing angles;

[0024] Figure 8 This is a schematic diagram of the position of the moving knife when starting to sew;

[0025] Fig. 9 This is a schematic diagram of the relative position of the moving knife and the pressing plate after the first needle;

[0026] Fig.10 This is a schematic diagram of the position of the moving knife when cutting the thread;

[0027] Fig.11 It is a schematic diagram of the structure of the moving knife;

[0028] Fig.12 is a schematic diagram of the connection structure between the drive motor and the tooth lifting transmission assembly in the first embodiment;

[0029] Fig.13 This is a schematic diagram of the structure of the tooth lifting eccentric wheel;

[0030] Fig.14 This is a schematic diagram of the structure of the right crank for lifting the teeth;

[0031] Fig.15 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;

[0032] Fig.16 It is a schematic diagram of the relative positions of the thread trimming driving member and the thread trimming fork crank when the thread lifting roller abuts against the tooth height adjustment section of the thread lifting driving cam;

[0033] Fig.17 It is a schematic diagram of the structure of the driving motor and the tooth lifting transmission assembly in the second embodiment.

[0034] Component number description:

[0035] 1. Chassis

[0036] 2 Bottom plate

[0037] 21 Needle plate

[0038] 3 Upper axis

[0039] 4 Tooth lifting axis

[0040] 41 Feed eccentric wheel

[0041] 42 tooth lifting connecting rod

[0042] 43 tooth lift right fork crank

[0043] 44 Sliders

[0044] 45 Tooth lift right crank

[0045] 451 First connection

[0046] 452 Second connection

[0047] 46 Eccentric wheel for lifting teeth

[0048] 461 First shaft section

[0049] 462 Second shaft section

[0050] 47 Torsion spring

[0051] 48 Retaining ring

[0052] 5 Feed axis

[0053] 6. Drive Motor

[0054] 61 Output shaft

[0055] 62 Mounting bracket

[0056] 71 lifting tooth drive cam

[0057] 72 tooth lifting roller

[0058] 721 Drive adjustment lever

[0059] 722 Second connecting rod

[0060] 731 Drive adjustment left crank

[0061] 732 Drive adjustment right crank

[0062] 74 Drive shaft

[0063] 751 drive shaft left sleeve

[0064] 752 drive shaft right sleeve

[0065] 76 First connecting rod

[0066] 81 Thread trimmer drive

[0067] 811 Trimming roller

[0068] 82 Trimming fork crank

[0069] 83 Stop bracket

[0070] 831 Stop pad

[0071] 84 Reset torsion spring

[0072] 85 Trimming crank

[0073] 86 Trimming rod

[0074] 87 Tool holder pressure plate

[0075] 88 Thread trimmer

[0076] 881 Thread trimmer sleeve

[0077] 91 Lifting left fork crank

[0078] 92 tooth frame

[0079] 93 Platen

[0080] 94 Knife

[0081] 941 Pinhole

[0082] 942 Moving blade edge

[0083] 943 Moving blade tip

[0084] 944 Line Drawing Department

[0085] 95 Fixed Knife

[0086] 96 Thread nozzle

[0087] 97 Moving tool holder

[0088] 98 Needle

[0089] 99 Tooth frame

[0090] 991 Feed dog DETAILED DESCRIPTION

[0091] 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.

[0092] 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.

[0093] 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.

[0094] Figure 1 The utility model sewing machine is shown in a three-dimensional diagram. In the following description, Figure 1 The attached figure in the figure is used as a reference for the direction. Figure 1 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.

[0095] like Figure 1-3 As shown, the utility model provides a sewing machine, which 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, an upper shaft 3 rotatably arranged in the casing 1, a tooth rack 99, a feed tooth 991 installed on the tooth rack 99, a tooth lifting mechanism connected to the rear end of the tooth rack 99, a feeding mechanism connected to the front end of the tooth rack 99, a thread cutting mechanism, a driving motor 6, a tooth lifting transmission assembly and a thread cutting transmission assembly. The driving motor 6 is fixedly installed on the base plate 2 through a mounting bracket 62, and a tooth lifting driving cam 71 and a thread cutting driving member 81 are respectively fixed on its output shaft 61. The outer periphery of the tooth lifting driving cam 71 has independent thread cutting and anti-bird nesting sections, tooth height adjustment sections and lower supply sections. The tooth lifting transmission assembly includes a rotatable tooth lifting roller 72, which abuts against the outer periphery of the tooth lifting driving cam 71. The tooth lifting driving cam 71 is connected to the tooth lifting mechanism through the tooth lifting transmission assembly; the thread cutting drive component 81 is connected to the thread cutting mechanism through the thread cutting transmission assembly.

[0096] In the above sewing machine, the tooth-lifting driving cam 71 and the thread-cutting driving member 81 rotate synchronously with the output shaft 61. The driving motor 6 can be as follows: Figure 2 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.

[0097] When the thread trimming anti-bird nest section abuts against the tooth lifting roller 72, the height of the feed tooth 991 remains unchanged at a set value, and power is transmitted between the thread trimming drive member 81 and the thread trimming transmission assembly. The drive motor 6 can drive the thread trimming 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 sewing thread when sewing is completed to complete the thread trimming.

[0098] When the tooth height adjustment section abuts against the tooth lifting roller 72, the height of the feed tooth 991 changes with the rotation of the output shaft 61, realizing stepless adjustment of the height of the feed tooth 991. In this process, there is no power transmission between the thread trimming drive member 81 and the thread trimming transmission assembly, and the thread trimming mechanism remains stationary.

[0099] When the lower feeding section contacts the tooth lifting roller 72, 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 pop out of the needle plate 21, so that the sewing machine has a lower feeding function. In conjunction 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 of uneven and unsmooth placement of the sewing material caused by the feed tooth 991 hanging on the sewing material. In this process, there is no power transmission between the thread trimming drive 81 and the thread trimming transmission assembly, and the thread trimming mechanism remains stationary.

[0100] The above sewing machine can adjust the height of the feed dog 991 in real time during the sewing process to achieve functions such as sewing trajectory change and stitch length compensation, thereby achieving better sewing effects. The specific description is as follows:

[0101] Combination Figure 2 It can be known that the feeding mechanism includes a feeding shaft 5 rotatably arranged in the base plate 2 and a tooth rack seat 92 arranged at the left end of the feeding shaft 5, and the tooth rack seat 92 is hinged to the front end of the tooth rack 99. The tooth lifting mechanism includes a tooth lifting shaft 4 rotatably arranged in the base plate 2, a tooth lifting left fork crank 91 fixed at the left end of the tooth lifting shaft 4, and a tooth lifting slider slidably assembled in the opening of the left fork crank 91, and the tooth lifting slider is hinged to the rear end of the tooth rack 99. The feeding shaft 5, the tooth lifting shaft 4, and the upper shaft 3 all extend 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, the feeding mechanism drives the tooth rack 99 and the feed tooth 991 to make a forward and backward reciprocating motion parallel to the X-axis direction, and the tooth lifting mechanism drives the tooth rack 99 and the feed tooth 991 to make an up and down reciprocating motion parallel to the Y-axis direction, and finally the feed tooth 991 moves as follows Figure 4The 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 4 The elliptical trajectory shown becomes Figure 5 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 sewing machine provided by the utility model can realize multiple functions such as preventing bird nests, thread cutting, adjusting feed dog height, lower feeding, track changing, etc. 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.

[0104] like Figure 2 , Figure 6-7 As shown, specifically, the wire cutting drive member 81 is a crank, and a rotatable wire cutting roller 811 is provided at its end. 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 there is power transmission between the two. When the tooth height adjustment section or the lower supply section abuts against the tooth lifting roller 72, the wire cutting roller 811 is separated from the wire cutting fork crank 82, and there is no power transmission between the two.

[0105] 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.

[0106] like Figure 9-11 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.

[0107] 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:

[0108] like Figure 8As 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. 9 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.10 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.

[0109] 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.

[0110] The tooth lifting transmission assembly has various forms. The following describes the first and second embodiments of the tooth lifting transmission assembly in conjunction with the accompanying drawings:

[0111] like Figure 2-3 , Figure 12-14 As shown, the tooth lifting transmission assembly in the first embodiment includes a rotating driving source, a tooth lifting right fork crank 43 fixed to the right end of the tooth lifting shaft 4, a tooth lifting eccentric wheel 46 sleeved on the tooth lifting shaft 4, and a tooth lifting right crank 45 sleeved on the tooth lifting eccentric wheel 46. The tooth lifting eccentric wheel 46 is shown in FIG. Fig.13As shown, it includes a first shaft segment 461 and a second shaft segment 462 that are connected to each other, the first shaft segment 461 and the second shaft segment 462 are eccentrically arranged, and the first shaft segment 461 is coaxially arranged with the tooth lifting shaft 4. The first shaft segment 461 is connected to the tooth lifting roller 72. The tooth lifting right crank 45 is sleeved on the second shaft segment 462 and abuts against the tooth lifting right fork-shaped crank 43. The tooth lifting right crank 45 includes a first connecting portion 451 and a second connecting portion 452, both of which extend along the radial direction of the tooth lifting right crank 45, and there is an angle between the two. The first connecting portion 451 is connected to the rotary drive source, and a rotatable slider 44 is provided on the second connecting portion 452, and the slider 44 is movably arranged in the slot of the tooth lifting right fork-shaped crank 43.

[0112] A torsion spring 47 is also sleeved on the first shaft section 461, one end of which abuts against the bottom plate 2, and the other end is connected to the first shaft section 461. 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. 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.

[0113] 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.

[0114] The tooth lifting transmission assembly also includes an adjustment driving lever 721 whose one end is hinged to the mounting bracket 62, and the tooth lifting roller 72 is rotatably arranged on the adjustment driving lever 721. The other end of the adjustment driving lever 721 is transmission-connected to the first shaft section 461 through a crank-connecting rod assembly. The crank-connecting rod assembly specifically 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 is fixedly connected to the drive adjustment right 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 is fixedly connected to the drive adjustment left crank 731, which is hinged to the adjustment driving lever 721 through the second connecting rod 722. 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.

[0115] The outer periphery of the tooth lifting driving cam 71 is specifically pear-shaped with one end small and the other end large. The lower supply section is located at the small head, away from the rotation center of the tooth lifting driving cam 71; the thread trimming and bird nest prevention section is located at the large head, concentrically arranged with the rotation center of the tooth lifting driving cam 71, and is an equal diameter section; the tooth height adjustment section is located between the small head and the large head, and is a variable diameter section. The tooth lifting eccentric wheel 46 transmits the force of the torsion spring 47 through the crank connecting rod assembly, so that the tooth lifting roller 72 always abuts against the outer periphery of the tooth lifting driving cam 71.

[0116] When the drive motor 6 is not working, the upper shaft 3 rotates under the driving action of the rotating drive source, driving the feeding eccentric wheel 41 to rotate, and then drives the right tooth lifting crank 45 to swing around the second shaft section 462 through the tooth lifting connecting rod 42, and drives the right tooth lifting fork crank 43 to swing through the slider 44. Since the right tooth lifting fork crank 43 is fixed at the right end of the tooth lifting shaft 4, the tooth lifting shaft 4 swings accordingly, and finally drives the left tooth lifting fork crank 91 to swing up and down, realizing the tooth lifting action.

[0117] like Fig.16As shown, when the tooth height adjustment section contacts the tooth lifting roller 72, the drive motor 6 works, and the tooth lifting roller 72 moves along the tooth height adjustment section with a variable diameter to generate displacement, and the tooth lifting eccentric wheel 46 rotates around the axis direction of the tooth lifting shaft 4 by driving the adjustment lever 28 and the crank connecting rod assembly, and the tooth lifting right crank 45 sleeved thereon rotates accordingly, and 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 height of the feed tooth 991. Therefore, the drive motor 6 can realize stepless adjustment of the height of the feed tooth 991. In this process, the wire cutting drive 81 is separated from the wire cutting fork crank 82, and the wire cutting crank 85 is against the stop pad 831, and the wire cutting mechanism remains stationary.

[0118] like Fig.15 As shown, when the lower feeding section abuts against the tooth lifting roller 72, the driving motor 6 works, 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 does not emerge from the needle plate 21. In this process, the thread trimming drive member 81 is separated from the thread trimming fork crank 82, the thread trimming crank 85 abuts against the stop pad 831, and the thread trimming mechanism remains stationary.

[0119] When the thread trimming anti-bird nest section abuts against the tooth lifting roller 72, the drive motor 6 works, and the tooth lifting roller 72 does not move along the thread trimming anti-bird nest section of equal diameter, so the height of the feed tooth 991 remains unchanged, which is a set value, and the thread trimming drive member 81 contacts and cooperates with the slot of the thread trimming fork crank 82. The drive motor 6 can drive the thread trimming mechanism to cut off the upper thread end when the sewing machine starts sewing, achieving the anti-bird nest effect, or cut off the suture when sewing is completed to complete the thread trimming.

[0120] like Fig.17 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 in the crank connecting rod assembly. It can realize the same feed dog height adjustment function as in the first embodiment.

[0121] 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 sewing machine, comprising a tooth frame, a feed tooth mounted on the tooth frame, a tooth lifting mechanism connected to one end of the tooth frame, and a thread cutting mechanism, characterized in that: It also includes a driving motor, a tooth lifting transmission assembly and a thread cutting transmission assembly, wherein a tooth lifting driving cam and a thread cutting driving member are respectively arranged on the output shaft of the driving motor, the outer periphery of the tooth lifting driving cam has mutually independent thread cutting anti-bird nest section, tooth height adjustment section and lower supply section, the tooth lifting transmission assembly includes a rotatable tooth lifting roller, the tooth lifting roller abuts against the outer periphery of the tooth lifting driving cam, the tooth lifting driving cam is connected to the tooth lifting mechanism through the tooth lifting transmission assembly; the thread cutting driving member is connected to the thread cutting mechanism through the thread cutting transmission assembly; When the thread trimming anti-bird nest section abuts against the tooth lifting roller, the height of the feed tooth remains unchanged, and power is transmitted between the thread trimming drive member and the thread trimming transmission assembly to drive the thread trimming mechanism to move; 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, and no power is transmitted between the thread trimming drive member and the thread trimming transmission assembly; When the lower feeding section is in contact with the tooth-lifting roller, the height of the feeding tooth is not greater than zero, and there is no power transmission between the thread trimming drive component and the thread trimming transmission assembly.

2. The sewing machine according to claim 1, characterized in that: The end of the thread trimming driving member is provided with a rotatable thread trimming roller, and the thread trimming transmission assembly includes a thread trimming shaft rotatably arranged in the bottom plate, a thread trimming fork crank fixedly connected to one end of the thread trimming shaft, a thread trimming crank fixedly connected to the other end of the thread trimming shaft, and a thread trimming connecting rod hinged to the thread trimming crank, and the thread trimming connecting rod is connected to the thread trimming mechanism; When the thread trimming anti-bird nest section abuts against the tooth lifting roller, the thread trimming roller contacts and cooperates with the slot of the thread trimming fork crank; When the tooth height adjustment section or the lower supply section abuts against the tooth lifting roller, the thread trimming roller is separated from the thread trimming fork crank.

3. The sewing machine according to claim 2, characterized in that: The thread trimming mechanism comprises a movable knife frame rotatably arranged on a bottom plate, a movable knife fixed on the movable knife frame, a fixed knife and a pressure plate fixed on the bottom plate, wherein the fixed knife and the pressure plate are arranged above the movable knife in sequence from bottom to top, and the movable knife frame is hinged to the thread trimming connecting rod.

4. The sewing machine according to claim 3, characterized in that: The movable knife is provided with a movable knife tip, a needle drop hole and a thread hooking part. The needle drop hole allows the machine needle to pass through. The movable knife is provided with a movable knife edge on the surface facing the fixed knife. The needle drop hole and the thread hooking part are distributed on one side of the movable knife edge, and the movable knife tip is distributed on the other side of the movable knife edge.

5. The sewing machine according to claim 2, characterized in that: The thread trimmer transmission assembly further comprises a reset torsion spring sleeved on the thread trimmer shaft, one end of the reset torsion spring abuts against the bottom plate, and the other end is connected to the thread trimmer crank.

6. The sewing machine according to claim 5, characterized in that The thread trimmer transmission assembly further comprises a stop bracket fixed on the bottom plate, and a stop pad is provided on the stop bracket; When the tooth height adjustment section or the lower supply section abuts against the tooth lifting roller, the thread trimming crank abuts against the stop pad.

7. The sewing machine according to claim 2, characterized in that: The wire cutting transmission assembly also includes a wire cutting shaft sleeve sleeved outside the wire cutting shaft, the wire cutting fork crank abuts against one end surface of the wire cutting shaft sleeve, and the wire cutting crank abuts against the other end surface of the wire cutting shaft sleeve.

8. The sewing machine according to claim 1, characterized in that The driving motor is a single-shaft motor or a double-shaft motor at both ends.

9. The sewing machine according to claim 1, characterized in that The tooth lifting mechanism includes a tooth lifting shaft rotatably arranged in the base plate, 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, and the tooth lifting slider is movably arranged in the slot of the left fork crank of the tooth lifting; the tooth lifting transmission assembly includes a rotational driving source, a tooth lifting right 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 includes a first shaft segment and a second shaft segment connected to each other, the first shaft segment is eccentrically arranged with the second shaft segment, and the first shaft segment is coaxially arranged with the tooth lifting shaft; the second shaft segment is sleeved with a tooth lifting right crank, and the right tooth lifting crank is provided with a rotatable slider, and the slider is movably arranged in the slot of the right fork crank of the tooth lifting; the tooth lifting right crank is connected to the rotational driving source, and the first shaft segment is connected to the tooth lifting roller.

10. The sewing machine according to claim 9, characterized in that The tooth lifting transmission assembly also 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.

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