A thread trimming control method for a sewing machine

Abstract

The present invention provides a method for controlling thread trimming of a sewing machine, which includes the following steps in sequence: S1, configuring the sewing machine: when the main shaft rotates to a set angle θ, the coaxial hinge axis of the cloth feed connecting rod, the first cloth feed rocker and the second cloth feed rocker coincides with the first fixed rotation axis of the cloth feed swing seat; S2, thread trimming of the sewing machine: the driving motor rotates from the current rotation angle value in the stitch length adjustment area to the end point of the thread trimming area, and the thread trimming mechanism performs the thread trimming action; S3, resetting the sewing machine after thread trimming: the main shaft is rotated to a set angle θ; the driving motor rotates from the end point of the thread trimming area to the current rotation angle value in the stitch length adjustment area, and the thread trimming mechanism performs the resetting action, and the stitch length of the sewing machine is reset from the thread trimming stitch length to the current effective stitch length, but the feed dog remains stationary. In the present application, when the driving motor needs to be reset to the state before thread trimming after the thread trimming mechanism cuts the suture, the feed dog remains stationary, thereby avoiding the feed dog from moving back and forth during the stitch length resetting process after thread trimming, bringing a better experience.

Description

Technical Field

[0001] The invention relates to the field of sewing machines, and in particular to a thread trimming control method for sewing machines. Background Art

[0002] With the continuous development of motor control technology, the structure and control method of sewing machines are also constantly updated. At present, there are endless ways to use stepper motors to directly control various mechanisms of sewing machines. Although this replaces the traditional complex mechanical transmission process and improves the transmission efficiency, it also brings about the influence of the timing of actions between each other and generates new problems. For example: when a single stepper motor is used to simultaneously realize the technology of adjusting the stitch length, lifting the presser foot and trimming the thread, when a single stepper motor realizes one of the actions, it will directly or indirectly interfere with the other two actions. When the thread trimming action is realized, the stitch length of the sewing machine will change from the effective sewing stitch length to the thread trimming stitch length; when sewing starts after the thread trimming is completed, the stitch length of the sewing machine will change from the thread trimming stitch length to the effective sewing stitch length. The stitch length reset process of the stitch length from the thread trimming stitch length to the effective sewing stitch length will cause the feed dog to move back and forth. If the feed dog moves back and forth above the needle plate, it will cause the fabric to move back and forth, affecting the customer experience. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a thread trimming control method for a sewing machine, which can prevent the feed dog from moving back and forth during the stitch resetting process after thread trimming.

[0004] To achieve the above-mentioned purpose, the present invention provides a sewing machine thread trimming control method, which is used for a sewing machine;

[0005] The sewing machine is provided with a rotatable main shaft, a feed dog, a feed mechanism, a thread trimming mechanism, a driving motor, a stitch length adjusting member and a thread trimming driving member all driven to rotate by the driving motor, a stitch length adjusting unit, and a thread trimming driving unit; the feed mechanism comprises a feed shaft parallel to the main shaft, a first feed unit connected between the main shaft and the feed shaft, and a second feed unit connected between the feed shaft and the feed dog, wherein the first feed unit comprises a feed eccentric wheel fixed on the main shaft, a feed connecting rod, a first feed rocker, a second feed rocker, a feed rocker with a first fixed rotation axis, The cloth feed crank is fixed on the cloth feed shaft, one end of the cloth feed connecting rod is rotatably mounted on the outer periphery of the cloth feed eccentric wheel, the other end of the cloth feed connecting rod, one end of the first cloth feed rocker and one end of the second cloth feed rocker are coaxially hinged, the other end of the first cloth feed rocker is hinged to the cloth feed swing seat, and the other end of the second cloth feed rocker is hinged to the cloth feed crank; the stitch length adjusting member is connected to the cloth feed swing seat through the stitch length adjusting unit, the thread trimming driving member is connected to the thread trimming mechanism through the thread trimming driving unit, and the rotation angle of the driving motor has a stitch length adjusting area and a thread trimming area that are independent of each other;

[0006] The sewing machine thread trimming control method comprises the following steps in sequence:

[0007] S1. Configuring the sewing machine: when the main shaft rotates to a set angle θ, the coaxial hinge axis of the cloth feed connecting rod, the first cloth feed swing rod and the second cloth feed swing rod coincides with the first fixed rotation axis of the cloth feed swing seat;

[0008] S2, thread trimming of the sewing machine: the drive motor rotates from the current rotation angle value in the stitch length adjustment area to the end point of the thread trimming area, the drive motor drives the stitch length adjustment member and the thread trimming drive member to rotate, the stitch length adjustment member acts on the cloth feeding swing seat through the stitch length adjustment unit, so that the stitch length of the sewing machine changes from the current effective stitch length to the thread trimming stitch length, and the thread trimming drive member acts on the thread trimming mechanism through the thread trimming drive unit, so that the thread trimming mechanism performs the thread trimming action;

[0009] S3, the sewing machine resets after thread trimming:

[0010] S31, first, rotating the main shaft to a set angle θ;

[0011] S32. Secondly, the driving motor rotates from the end point of the thread trimming area to the current rotation angle value in the stitch length adjustment area, and the driving motor drives the stitch length adjustment member and the thread trimming driving member to rotate. The stitch length adjustment member acts on the cloth feed swing seat through the stitch length adjustment unit to reset the stitch length of the sewing machine from the thread trimming stitch length to the current effective stitch length, but the cloth feed dog remains stationary, and the thread trimming driving member acts on the thread trimming mechanism through the thread trimming driving unit to reset the thread trimming mechanism.

[0012] Furthermore, in the step S2, when the driving motor rotates to the end point of the thread trimming area, the rotation angle of the main shaft is a thread trimming engagement angle φ, and the thread trimming engagement angle φ is smaller than a set angle θ.

[0013] Further, the stitch length adjustment member is an adjustment cam, the outer peripheral surface of which includes a variable diameter contour surface and a constant diameter contour surface; the stitch length adjustment unit includes a stitch length adjustment crank with a second fixed rotation axis, a stitch length adjustment ball rotatably mounted on the stitch length adjustment crank, and a stitch length adjustment connecting rod, the stitch length adjustment ball is in contact with the outer peripheral surface of the adjustment cam, and the two ends of the stitch length adjustment connecting rod are respectively hinged to the stitch length adjustment crank and the cloth feeding swing seat;

[0014] When the drive motor is running in the stitch length adjustment area, the stitch length adjustment ball contacts and cooperates with the variable diameter contour surface on the outer periphery of the adjustment cam, and the stitch length of the sewing machine is the effective stitch length;

[0015] When the driving motor runs in the thread trimming area, the stitch length adjusting ball contacts and cooperates with the equal-diameter contour surface on the outer periphery of the adjusting cam, and the stitch length of the sewing machine is maintained at the thread trimming stitch length.

[0016] Furthermore, the step S2 includes the following sub-steps in sequence:

[0017] S21, the sewing machine runs the last stitch, the main shaft has a lower corner area corresponding to the feed dog below the needle plate, and an upper corner area corresponding to the feed dog emerging upward from the needle plate, and the lower corner area and the upper corner area are connected end to end;

[0018] S22, the spindle rotates from the starting point of the lower corner area to the end point. During this process, the feed dog is located below the needle plate, the drive motor rotates from the current angle value in the stitch length adjustment area to the starting point of the thread trimming area, the stitch length of the sewing machine changes from the current effective stitch length to the thread trimming stitch length, and the thread trimming mechanism does not operate;

[0019] S23, the main shaft rotates from the starting point of the upper corner area in the upper corner area. During this process, the feed dog emerges upward from the needle plate, and the drive motor rotates from the starting point to the end point of the thread trimming area. The stitch length of the sewing machine is maintained at the thread trimming stitch length, and the thread trimming mechanism performs the thread trimming action.

[0020] Furthermore, the thread trimming drive component is a thread trimming cam, a thread trimming drive arm extends from the outer circumference of the thread trimming cam, the thread trimming drive unit includes a thread trimming drive lever with a third fixed rotation axis, a thread trimming ball rotatably mounted on the thread trimming drive arm, and a thread trimming drive connecting rod, the thread trimming ball can contact and cooperate with the outer circumference of the thread trimming drive lever, one end of the thread trimming drive connecting rod is hinged to the thread trimming drive lever, and the other end is connected to the thread trimming mechanism.

[0021] Furthermore, a forced reset arm extends from the outer circumferential surface of the thread trimming cam, and the forced reset arm is circumferentially staggered with the thread trimming drive arm. A rotatable forced reset ball is installed on the thread trimming drive lever, and the forced reset ball can contact and cooperate with the outer circumferential surface of the forced reset arm.

[0022] Furthermore, the thread trimming mechanism includes a thread trimming shaft rotatably installed in the sewing machine base plate, a first thread trimming crank and a second thread trimming crank both fixed to the thread trimming shaft, a thread trimming connecting rod, a movable knife frame, a movable knife fixed to the movable knife frame, and a fixed knife fixed to the sewing machine base plate, the thread trimming drive connecting rod is hinged to the first thread trimming crank, and the two ends of the thread trimming connecting rod are respectively hinged to the second thread trimming crank and the movable knife frame.

[0023] Furthermore, the thread trimming mechanism also includes a reset torsion spring sleeved on the thread trimming shaft, and two ends of the reset torsion spring are respectively connected to the second thread trimming crank and the sewing machine bottom plate.

[0024] As described above, the sewing machine thread trimming control method according to the present invention has the following beneficial effects:

[0025] In the present application, after the thread trimming mechanism cuts the thread, the driving motor needs to be reset to the state before the thread trimming, and the stitch length of the sewing machine is correspondingly reset from the thread trimming stitch length to the current effective stitch length. During this process, the main shaft stays at the set angle θ, and the sewing machine maintains a state in which the coaxial hinge axis of the feed connecting rod, the first feed rocker arm and the second feed rocker arm coincide with the first fixed rotation axis of the feed swing seat. Although the driving motor drives the feed swing seat to rotate through the stitch length adjusting member and the stitch length adjusting unit, so that the stitch length of the sewing machine is reset from the thread trimming stitch length to the current effective stitch length, the feed swing seat will not transmit force to the feed crank, thereby keeping the feed shaft, the second feed unit and the feed dog stationary, thereby avoiding the feed dog from moving back and forth during the stitch length resetting process after thread trimming, giving users a better experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of the thread trimming control method of a sewing machine in this application.

[0027] Figure 2 It is a structural schematic diagram of the sewing machine in this application.

[0028] Figure 3 for Figure 2 Schematic diagram of the structure after omitting the casing and base plate.

[0029] Figure 4 and Figure 5 Schematic diagram of the connection between the driving motor, the needle distance adjusting member, the needle distance adjusting unit and the first cloth feeding unit in the present application at different viewing angles.

[0030] Figure 6 It is a schematic diagram of the structure of the needle distance adjustment member in this application.

[0031] Figure 7 It is a connection diagram of the driving motor, the thread trimming driving member, the thread trimming driving unit and the thread trimming mechanism in this application.

[0032] Figure 8 It is a schematic diagram of the connection between the thread trimming driving member and the thread trimming driving lever in the present application.

[0033] Fig. 9 It is a schematic diagram of the structure of the thread trimming drive component in this application.

[0034] Component number description

[0035] 10 Spindle

[0036] 20 Feed dog

[0037] 30 Drive Motor

[0038] 40 Needle length adjustment

[0039] 41 Reduced profile surface

[0040] 42 Constant diameter profile surface

[0041] 50 Thread cutting drive

[0042] 51 Thread trimmer drive arm

[0043] 52 Forced return arm

[0044] 61 Thread trimmer drive lever

[0045] 62 Trimming ball

[0046] 63 Thread trimmer drive connecting rod

[0047] 64 Forced return ball

[0048] 71 Feed shaft

[0049] 72 Feed eccentric wheel

[0050] 73 cloth feeding connecting rod

[0051] 74 First cloth feeding lever

[0052] 75 Second cloth feeding lever

[0053] 76 Feeding swing seat

[0054] 77 Feed crank

[0055] 78 tooth frame

[0056] 79 Tooth frame

[0057] 81 Thread trimmer

[0058] 82 First Trimming Crank

[0059] 83 Second trimmer crank

[0060] 84 Thread trimmer connecting rod

[0061] 85 Moving tool holder

[0062] 86 Knife

[0063] 87 Fixed Knife

[0064] 91 Stitch adjustment crank

[0065] 92 Needle Length Adjustment Ball

[0066] 93 Needle length adjustment lever

[0067] 110 Base Plate

[0068] 120 Chassis DETAILED DESCRIPTION

[0069] The following is a description of the implementation of the present invention by means of specific embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0070] It should be noted that the structures, proportions, sizes, etc. drawn in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not used to limit the limiting conditions for the implementation of the present invention, so they have no substantial technical significance. Any modification of the structure, change of the proportional relationship or adjustment of the size should still fall within the scope of the technical content disclosed by the present invention without affecting the effects and purposes that can be achieved by the present invention. At the same time, the terms such as "upper", "lower", "left", "right", "middle" and "one" quoted in this specification are only for the convenience of description, and are not used to limit the scope of the implementation of the present invention. The change or adjustment of their relative relationship should also be regarded as the scope of the implementation of the present invention without substantially changing the technical content.

[0071] The present application provides a sewing machine thread trimming control method for a sewing machine.

[0072] like Figure 2 and Figure 3 As shown, the sewing machine is a flat sewing machine, which is equipped with a bottom plate 110, a housing 120 fixed above the bottom plate 110, a main shaft 10 extending left and right and rotatably supported in the housing 120, a main motor driving the main shaft 10 to rotate, a needle plate fixed at the left end of the bottom plate 110, a feed dog 20, a cloth feeding mechanism, a thread trimming mechanism, a driving motor 30 fixed at the right end of the housing 120, a needle distance adjustment member 40 and a thread trimming driving member 50 both driven to rotate by the driving motor 30, a needle distance adjustment unit, and a thread trimming driving unit. Among them, a tooth groove extending forward and backward is opened in the needle plate, and the tooth groove allows the feed dog 20 to emerge upward from the needle plate and allow the feed dog 20 to reciprocate forward and backward.

[0073] Furthermore, if Figures 3 to 5As shown, the cloth feeding mechanism includes a cloth feeding shaft 71 parallel to the main shaft 10 , a first cloth feeding unit connected between the main shaft 10 and the cloth feeding shaft 71 , and a second cloth feeding unit connected between the cloth feeding shaft 71 and the cloth feeding dog 20 . The first cloth feeding unit includes a cloth feeding eccentric wheel 72 fixed on the main shaft 10 by screws, a cloth feeding connecting rod 73, a first cloth feeding rocker 74, a second cloth feeding rocker 75, a cloth feeding swing seat 76 having a first fixed rotation axis, and a cloth feeding crank 77 fixed to the right end of the cloth feeding shaft 71. The upper end of the cloth feeding connecting rod 73 is rotatably mounted on the outer periphery of the cloth feeding eccentric wheel 72. The lower end of the cloth feeding connecting rod 73, one end of the first cloth feeding rocker 74 and one end of the second cloth feeding rocker 75 are coaxially hinged by a pin extending left and right. The other end of the first cloth feeding rocker 74 is hinged to the cloth feeding swing seat 76, and the other end of the second cloth feeding rocker 75 is hinged to the cloth feeding crank 77. The left and right sides of the cloth feeding swing seat 76 are rotatably mounted on a supporting pin extending left and right. The supporting pin is fixed in the casing 120. The supporting pin constitutes the first fixed rotation axis of the cloth feeding swing seat 76, and the cloth feeding swing seat 76 can rotate around the supporting pin. The second cloth feeding unit includes a tooth frame seat 78 fixed to the left end of the cloth feeding shaft 71, a connecting pin, and a tooth frame 79. The tooth frame seat 78 is connected to the front end of the tooth frame 79 through the connecting pin, and the cloth feeding tooth 20 is fixed to the upper end surface of the tooth frame 79. The stitch length adjustment member 40 is connected to the cloth feeding swing seat 76 through the stitch length adjustment unit, and the thread trimming drive member 50 is connected to the thread trimming mechanism through the thread trimming drive unit.

[0074] like Figure 3 and Figure 7 As shown, the thread trimming mechanism includes a thread trimming shaft 81 extending left and right and rotatably mounted in the sewing machine bottom plate 110, a first thread trimming crank 82 fixed to the right end of the thread trimming shaft 81, a second thread trimming crank 83 fixed to the left end of the thread trimming shaft 81, a thread trimming connecting rod 84, a movable knife frame 85, a movable knife 86 fixed to the movable knife frame 85, and a fixed knife 87 fixed to the sewing machine bottom plate 110, the first thread trimming crank 82 is connected to the thread trimming drive unit, and the two ends of the thread trimming connecting rod 84 are respectively hinged to the second thread trimming crank 83 and the movable knife frame 85. Preferably, the thread trimming mechanism also includes a reset torsion spring sleeved on the thread trimming shaft 81, the two ends of the reset torsion spring are respectively connected to the second thread trimming crank 83 and the sewing machine bottom plate 110, and the reset torsion spring is used to reset the movable knife 86, the movable knife frame 85, the second thread trimming crank 83 and the thread trimming shaft 81 after thread trimming.

[0075] Furthermore, within the range of 360° of one rotation of the drive motor 30, the rotation angle of the drive motor 30 has a mutually independent stitch adjustment area and a thread trimming area. When the sewing machine is sewing normally, the drive motor 30 outputs the rotation angle value in the stitch adjustment area, and the drive motor 30 keeps the cloth feed swing seat 76 at a stable position angle through the stitch adjustment member 40 and the stitch adjustment unit. The sewing machine has an effective stitch length, which includes an effective forward stitch length corresponding to the forward stitch mode and an effective reverse stitch length corresponding to the reverse stitch mode. In this embodiment, the effective stitch length of the sewing machine is -7mm to 7mm. When the sewing machine needs to adjust the stitch length, the drive motor 30 rotates in the stitch length adjustment area, and the drive motor 30 drives the stitch length adjustment member 40 to rotate, and acts on the cloth feed swing seat 76 through the stitch length adjustment unit, changing the position angle of the cloth feed swing seat 76, thereby changing the transmission efficiency of the first cloth feed unit when the sewing machine is subsequently operated, thereby changing the movement amplitude of the main shaft 10 driving the cloth feed dog 20 to move back and forth through the cloth feed mechanism, and realizing stitch length adjustment. When the sewing machine needs to trim the thread, the drive motor 30 rotates from the current rotation angle in the stitch length adjustment area to the thread trimming area, and the drive motor 30 drives the thread trimming drive member 50 to rotate, and acts on the thread trimming mechanism through the thread trimming drive unit, and the thread trimming mechanism performs the thread trimming action, so that the movable knife 86 in the thread trimming mechanism moves toward the direction close to the fixed knife 87, until the movable knife 86 and the fixed knife 87 are engaged, and the suture is cut, realizing automatic thread trimming.

[0076] Furthermore, the sewing machine is also equipped with an electric control module, which is connected to the main motor and the drive motor 30 and sends various instructions to the drive motor 30. Figure 1 As shown, the sewing machine thread trimming control method involved in the present application comprises the following steps in sequence:

[0077] Step S1, configure the sewing machine: when the main shaft 10 rotates to the set angle θ, the coaxial hinge axis of the cloth feed connecting rod 73, the first cloth feed rocker 74 and the second cloth feed rocker 75 coincides with the first fixed rotation axis of the cloth feed swing seat 76. In this case, no matter how the position angle of the cloth feed swing seat 76 changes, the cloth feed dog 20 will not move forward or backward.

[0078] Step S2, thread trimming of the sewing machine: the driving motor 30 rotates from the current angle value in the stitch length adjustment area to the end point of the thread trimming area, and the driving motor 30 drives the stitch length adjusting member 40 and the thread trimming driving member 50 to rotate; the stitch length adjusting member 40 acts on the cloth feeding swing seat 76 through the stitch length adjustment unit, so that the stitch length of the sewing machine is changed from the current effective stitch length to the thread trimming stitch length, and the thread trimming stitch length refers to the stitch length of the sewing machine when the driving motor 30 outputs the angle in the thread trimming area; at the same time, the thread trimming driving member 50 acts on the thread trimming mechanism through the thread trimming driving unit, and the thread trimming mechanism performs the thread trimming action, so that the movable knife 86 and the fixed knife 87 in the thread trimming mechanism are engaged to cut the suture.

[0079] Step S3, resetting the sewing machine after thread trimming, specifically includes the following steps S31 and S32:

[0080] Step S31, first, the main shaft 10 is rotated to a set angle θ, so that the coaxial hinge axis of the cloth feed connecting rod 73, the first cloth feed swing rod 74 and the second cloth feed swing rod 75 in the sewing machine coincides with the first fixed rotation axis of the cloth feed swing seat 76;

[0081] Step S32, secondly, the driving motor 30 rotates from the end point of the thread trimming area to the current rotation angle value in the stitch length adjustment area, and the driving motor 30 needs to be reset to the state before thread trimming. In this process, the driving motor 30 drives the stitch length adjustment member 40 and the thread trimming driving member 50 to rotate, and the stitch length adjustment member 40 acts on the cloth feed swing seat 76 through the stitch length adjustment unit, so that the stitch length of the sewing machine is reset from the thread trimming stitch length to the current effective stitch length; the main shaft 10 stays at the set angle θ, and the sewing machine keeps the coaxial hinge axis of the cloth feed connecting rod 73, the first cloth feed swing rod 74 and the second cloth feed swing rod 75 coincident with the first fixed rotation axis of the cloth feed swing seat 76, although the driving motor 30 drives the stitch length adjustment member 40 through the stitch length adjustment member 40 The stitch length adjustment unit drives the cloth feed swing seat 76 to rotate, so that the stitch length of the sewing machine is reset from the thread trimming stitch length to the current effective stitch length, but the cloth feed swing seat 76 will not transmit force to the cloth feed crank 77, so that the cloth feed shaft 71, the second cloth feed unit and the cloth feed dog 20 remain stationary; at the same time, the thread trimming drive member 50 acts on the thread trimming mechanism through the thread trimming drive unit, and under the action of the reset spring in the thread trimming mechanism, each component is reset, that is, the movable knife 86 and the fixed knife 87 in the thread trimming mechanism are separated, and the thread trimming mechanism performs a reset action.

[0082] Therefore, during the process of resetting after thread trimming, the sewing machine in the present application can reset the stitch length of the sewing machine from the thread trimming stitch length to the current effective stitch length, but at the same time keep the feed dog 20 stationary and will not move back and forth, and there will be no situation where the feed dog 20 drives the fabric back and forth, ultimately giving the user a very good experience.

[0083] Furthermore, in the above step S2, when the drive motor 30 rotates to the end point of the thread trimming zone, the rotation angle of the spindle 10 at this time is the thread trimming engagement angle φ, which is less than the set angle θ. The drive motor 30 can be a stepper motor or a servo motor; the needle distance adjustment member 40 and the thread trimming drive member 50 are both fixed to the motor shaft of the drive motor 30 by screws. The needle distance adjustment member 40 and the thread trimming drive member 50 can be two independent components or combined into one integral component; Figure 3 In the embodiment shown, the stitch length adjusting member 40 and the thread trimming driving member 50 are two independent components, and the stitch length adjusting member 40 is located on the right side of the thread trimming driving member 50, which is more in line with the structural design of the sewing machine. Figure 2As shown, the sewing machine is also provided with a thread taking-up mechanism, which has a thread taking-up rod which can reciprocate up and down.

[0084] Furthermore, if Figure 4 and Figure 5 As shown, the stitch adjustment member 40 is an adjustment cam, and the stitch adjustment unit includes a stitch adjustment crank 91 having a second fixed rotation axis, a stitch adjustment ball 92 rotatably mounted on the stitch adjustment crank 91, and a stitch adjustment connecting rod 93. The stitch adjustment ball 92 contacts and cooperates with the outer peripheral surface of the adjustment cam, and the two ends of the stitch adjustment connecting rod 93 are respectively hinged to the stitch adjustment crank 91 and the cloth feeding swing seat 76. Figures 7 to 9 As shown, the thread trimming drive member 50 is a thread trimming cam, and a thread trimming drive arm 51 extends from the outer peripheral surface of the thread trimming cam. The thread trimming drive unit includes a thread trimming drive lever 61 with a third fixed rotation axis, a thread trimming ball 62 rotatably mounted on the thread trimming drive arm 51, and a thread trimming drive connecting rod 63. The thread trimming ball 62 can contact and cooperate with the outer peripheral surface of the thread trimming drive lever 61, one end of the thread trimming drive connecting rod 63 is hinged to the thread trimming drive lever 61, and the other end of the thread trimming drive connecting rod 63 is hinged to the first thread trimming crank 82 in the thread trimming mechanism.

[0085] Preferably, if Figures 7 to 9 As shown, a forced reset arm 52 is also extended from the outer circumferential surface of the thread trimming cam, and the forced reset arm 52 is circumferentially staggered with the thread trimming drive arm 51. A rotatable forced reset ball 64 is installed on the thread trimming drive lever 61, and the forced reset ball 64 can contact and cooperate with the outer circumferential surface of the forced reset arm 52. The contact and cooperation between the forced reset ball 64 and the forced reset arm 52 can drive the thread trimming mechanism to be forced reset, thereby reducing the occurrence of the knife jamming phenomenon.

[0086] Furthermore, if Figure 6As shown, the outer peripheral surface of the adjustment cam constituting the stitch length adjustment member 40 includes a variable diameter contour surface 41 and a constant diameter contour surface 42. When the drive motor 30 is running in the stitch length adjustment area, the stitch length adjustment ball 92 contacts and cooperates with the variable diameter contour surface 41 on the outer periphery of the adjustment cam, and the stitch length of the sewing machine is the effective stitch length; and the adjustment cam can drive the stitch length adjustment crank 91 to rotate through the stitch length adjustment ball 92, and the stitch length adjustment crank 91 drives the cloth feeding swing seat 76 to rotate through the stitch length adjustment connecting rod 93, thereby changing the effective stitch length of the sewing machine and realizing stitch length adjustment; however, the thread trimming ball 62 is separated from the outer peripheral surface of the thread trimming driving lever 61, and the thread trimming mechanism does not operate. When the driving motor 30 is running in the thread trimming area, the thread trimming ball 62 contacts and cooperates with the outer peripheral surface of the thread trimming driving lever 61, and the thread trimming ball 62 pushes the thread trimming driving lever 61 to rotate, and the first thread trimming crank 82 is driven to move by the thread trimming driving connecting rod 63, so as to drive the thread trimming mechanism to move, so that the movable knife 86 rotates in the direction close to the fixed knife 87; at the same time, the stitch length adjustment ball 92 contacts and cooperates with the equal-diameter contour surface 42 of the outer periphery of the adjustment cam, then the adjustment cam and the stitch length adjustment ball 92 do not transmit power, the stitch length adjustment crank 91 does not rotate, and the stitch length of the sewing machine remains as the thread trimming stitch length, which can be a small stitch length value close to 0, or a large stitch length value, which can be specifically set according to actual needs. When the thread trimming stitch length is a small stitch length value close to 0, it can be realized that the residual thread ends on the cloth after thread trimming are shorter. In addition, a loose thread drive section can be set on the right end face of the stitch length adjustment member 40 for loose thread drive of the sewing machine.

[0087] Furthermore, when the sewing machine trims the thread, it is the last stitch of the sewing machine. During this process, the turning angle of the main shaft 10 has a lower corner area corresponding to the feed dog 20 below the needle plate, and an upper corner area corresponding to the feed dog 20 emerging upward from the needle plate. The lower corner area and the upper corner area are connected end to end, and the main shaft 10 first rotates from the starting point of the lower corner area to its end point, and then rotates from the starting point of the upper corner area to its end point.

[0088] The above-mentioned sewing machine thread trimming control method can be used for the single thread trimming action of the sewing machine, and can also be used for the presser foot lifting action after thread trimming of the sewing machine. When the sewing machine thread trimming control method is used for the single thread trimming action of the sewing machine, the sewing machine thread trimming control method specifically includes the following steps:

[0089] A1. The thread trimming signal is triggered, and the electronic control module controls the main motor and the drive motor 30 to operate. The main motor drives the spindle 10 to rotate, and the spindle 10 rotates from the starting point of the lower corner area to the end point. During this process, the feed dog 20 is always located below the needle plate, and the drive motor 30 rotates from the current angle value in the stitch length adjustment area to the starting point of the thread trimming area. When the feed dog 20 does not emerge upward from the needle plate, the stitch length of the sewing machine changes from the current effective stitch length to the thread trimming stitch length, and the thread trimming mechanism does not operate.

[0090] A2. When the thread take-up lever is at its lowest position, the spindle 10 rotates from the starting point of the upper corner area in the upper corner area; during this process, the feed dog 20 emerges upward from the needle plate, and the drive motor 30 rotates from the starting point of the thread trimming area to the end point, the stitch length of the sewing machine is maintained at the thread trimming stitch length, and the thread trimming mechanism performs the thread trimming action, and the movable knife 86 in the thread trimming mechanism moves in the direction close to the fixed knife 87. When the drive motor 30 rotates to the end point of the thread trimming area, the movable knife 86 and the fixed knife 87 are fully engaged to cut the suture, and the rotation angle of the spindle 10 is the thread trimming engagement angle φ.

[0091] A3. The driving motor 30 maintains the terminal angle of the output thread trimming zone, and the main shaft 10 rotates from the thread trimming engagement angle φ to the set angle θ, so that the coaxial hinge axis of the cloth feed connecting rod 73, the first cloth feed rocker 74 and the second cloth feed rocker 75 coincides with the first fixed rotation axis of the cloth feed swing seat 76.

[0092] A4. The driving motor 30 quickly reverses from the end angle of the thread trimming area to the current angle value in the stitch length adjustment area before thread trimming. Under the joint action of the driving motor 30 and the reset torsion spring, the various components in the thread trimming mechanism are reset, and the stitch length of the sewing machine is also restored to the current effective stitch length before thread trimming, and the feed dog 20 will not move forward and backward.

[0093] When the thread trimming control method for a sewing machine is used for the presser foot lifting action after thread trimming of a sewing machine, if the presser foot lifting mechanism of the sewing machine is driven by a separate driving source such as a cylinder or an electromagnet, the thread trimming control method for a sewing machine is the same as steps A1 to A4 above. If the presser foot lifting mechanism of the sewing machine is driven simultaneously by a driving mechanism, the thread trimming control method for a sewing machine includes the following steps:

[0094] B1. The thread trimming signal is triggered, and the electronic control module controls the main motor and the drive motor 30 to operate. The main motor drives the spindle 10 to rotate, and the spindle 10 rotates from the starting point of the lower corner area to the end point. During this process, the feed dog 20 is always located below the needle plate, and the drive motor 30 rotates from the current angle value in the needle length adjustment area to the starting point of the thread trimming area. When the feed dog 20 does not emerge upward from the needle plate, the stitch length of the sewing machine changes from the current effective stitch length to the thread trimming stitch length, and the thread trimming mechanism does not operate.

[0095] B2. When the thread take-up lever is at its lowest position, the spindle 10 rotates from the starting point of the upper corner area in the upper corner area; during this process, the feed dog 20 emerges upward from the needle plate, and the drive motor 30 rotates from the starting point of the thread trimming area to the end point, the stitch length of the sewing machine remains the thread trimming stitch length, and the movable knife 86 in the thread trimming mechanism moves in the direction close to the fixed knife 87. When the drive motor 30 rotates to the end point of the thread trimming area, the movable knife 86 and the fixed knife 87 are fully engaged to cut the suture, and the rotation angle of the spindle 10 is the thread trimming engagement angle φ.

[0096] B3, the driving motor 30 maintains the terminal angle of the output thread trimming area, and the spindle 10 rotates from the thread trimming engagement angle φ to the set angle θ, after which the driving motor 30 continues to rotate in the same direction from the terminal angle of the thread trimming area to the presser foot lifting area of ​​the driving motor 30, driving the presser foot lifting mechanism to perform the presser foot lifting action, and the forced reset ball 64 and the forced reset arm 52 contact and cooperate to force the thread trimming mechanism to reset. Alternatively, after the thread trimming action is completed in step B2, the driving motor 30 continues to rotate in the same direction directly from the terminal angle of the thread trimming area to the presser foot lifting area of ​​the driving motor 30, without being linked to the rotation angle of the spindle 10, and the forced reset ball 64 and the forced reset arm 52 contact and cooperate to force the thread trimming mechanism to reset.

[0097] In summary, the present invention effectively overcomes various shortcomings of the prior art and has high industrial utilization value.

[0098] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A sewing machine thread trimming control method, used for a sewing machine; The sewing machine is provided with a rotatable main shaft (10), a cloth feed dog (20), a cloth feed mechanism, a thread trimming mechanism, a driving motor (30), a stitch length adjusting member (40) and a thread trimming driving member (50) both driven to rotate by the driving motor (30), a stitch length adjusting unit, and a thread trimming driving unit; the cloth feed mechanism comprises a cloth feed shaft (71) parallel to the main shaft (10), a first cloth feed unit connected between the main shaft (10) and the cloth feed shaft (71), and a second cloth feed unit connected between the cloth feed shaft (71) and the cloth feed dog (20); the first cloth feed unit comprises a cloth feed eccentric wheel (72) fixed on the main shaft (10), a cloth feed connecting rod (73), a first cloth feed rocker (74), a second cloth feed rocker (75), a cloth feed shaft having a first fixed rotation axis, and a second cloth feed connecting rod (74). A swing seat (76) and a cloth feed crank (77) fixed on the cloth feed shaft (71); one end of the cloth feed connecting rod (73) is rotatably mounted on the outer periphery of the cloth feed eccentric wheel (72); the other end of the cloth feed connecting rod (73), one end of the first cloth feed rocker (74) and one end of the second cloth feed rocker (75) are coaxially hinged; the other end of the first cloth feed rocker (74) is hinged to the cloth feed swing seat (76); the other end of the second cloth feed rocker (75) is hinged to the cloth feed crank (77); the stitch length adjusting member (40) is connected to the cloth feed swing seat (76) through a stitch length adjusting unit; the thread trimming driving member (50) is connected to the thread trimming mechanism through a thread trimming driving unit; the rotation angle of the driving motor (30) has a stitch length adjusting area and a thread trimming area that are independent of each other; Features: The sewing machine thread trimming control method comprises the following steps in sequence: S1. Configuring the sewing machine: when the main shaft (10) rotates to a set angle θ, the coaxial hinge axis of the cloth feed connecting rod (73), the first cloth feed swing rod (74) and the second cloth feed swing rod (75) coincides with the first fixed rotation axis of the cloth feed swing seat (76); S2, thread trimming of the sewing machine: the drive motor (30) rotates from the current rotation angle value in the stitch length adjustment area to the end point of the thread trimming area, the drive motor (30) drives the stitch length adjustment member (40) and the thread trimming drive member (50) to rotate, the stitch length adjustment member (40) acts on the cloth feeding swing seat (76) through the stitch length adjustment unit, so that the stitch length of the sewing machine changes from the current effective stitch length to the thread trimming stitch length, and the thread trimming drive member (50) acts on the thread trimming mechanism through the thread trimming drive unit, so that the thread trimming mechanism performs the thread trimming action; S3, the sewing machine resets after thread trimming: S31, first, rotating the main shaft (10) to a set angle θ; S32. Secondly, the drive motor (30) rotates from the end point of the thread trimming area to the current rotation angle value in the needle length adjustment area, and the drive motor (30) drives the needle length adjustment member (40) and the thread trimming drive member (50) to rotate. The needle length adjustment member (40) acts on the cloth feed swing seat (76) through the needle length adjustment unit, so that the needle length of the sewing machine is reset from the thread trimming needle length to the current effective needle length, but the cloth feed dog (20) remains stationary. The thread trimming drive member (50) acts on the thread trimming mechanism through the thread trimming drive unit, so that the thread trimming mechanism performs a reset action.

2. The sewing machine thread trimming control method according to claim 1, characterized in that: In the step S2, when the driving motor (30) rotates to the end point of the thread trimming area, the rotation angle of the main shaft (10) is a thread trimming engagement angle φ, and the thread trimming engagement angle φ is smaller than a set angle θ.

3. The sewing machine thread trimming control method according to claim 1, characterized in that: The stitch length adjustment member (40) is an adjustment cam, the outer peripheral surface of which includes a variable diameter contour surface (41) and a constant diameter contour surface (42); the stitch length adjustment unit includes a stitch length adjustment crank (91) having a second fixed rotation axis, a stitch length adjustment ball (92) rotatably mounted on the stitch length adjustment crank (91), and a stitch length adjustment connecting rod (93), the stitch length adjustment ball (92) being in contact with the outer peripheral surface of the adjustment cam, and the two ends of the stitch length adjustment connecting rod (93) are respectively hinged to the stitch length adjustment crank (91) and the cloth feeding swing seat (76); When the driving motor (30) operates in the stitch length adjustment area, the stitch length adjustment ball (92) contacts and cooperates with the variable diameter contour surface (41) on the outer periphery of the adjustment cam, and the stitch length of the sewing machine is an effective stitch length; When the driving motor (30) operates in the thread trimming area, the stitch length adjustment ball (92) contacts and cooperates with the equal-diameter contour surface (42) on the outer periphery of the adjustment cam, and the stitch length of the sewing machine is maintained at the thread trimming stitch length.

4. The sewing machine thread trimming control method according to claim 3, characterized in that: The step S2 comprises the following sub-steps in sequence: S21, the sewing machine runs the last stitch, the corner of the main shaft (10) has a lower corner area corresponding to the feed dog (20) below the needle plate, and an upper corner area corresponding to the feed dog (20) emerging upward from the needle plate, and the lower corner area and the upper corner area are connected end to end; S22, the main shaft (10) rotates from the starting point of the lower corner area to the end point. During this process, the feed dog (20) is located below the needle plate, and the drive motor (30) rotates from the current angle value in the needle length adjustment area to the starting point of the thread trimming area. The needle length of the sewing machine changes from the current effective needle length to the thread trimming needle length, and the thread trimming mechanism does not operate; S23, the main shaft (10) rotates in the upper corner area from the starting point of the upper corner area. During this process, the feed dog (20) emerges upward from the needle plate, and the drive motor (30) rotates from the starting point to the end point of the thread trimming area. The stitch length of the sewing machine is maintained at the thread trimming stitch length, and the thread trimming mechanism performs the thread trimming action.

5. The thread trimming control method of a sewing machine according to claim 1, characterized in that: The thread trimming drive member (50) is a thread trimming cam, and a thread trimming drive arm (51) extends from the outer peripheral surface of the thread trimming cam. The thread trimming drive unit comprises a thread trimming drive lever (61) having a third fixed rotation axis, a thread trimming ball (62) rotatably mounted on the thread trimming drive arm (51), and a thread trimming drive connecting rod (63). The thread trimming ball (62) can be in contact with the outer peripheral surface of the thread trimming drive lever (61). One end of the thread trimming drive connecting rod (63) is hinged to the thread trimming drive lever (61), and the other end is connected to the thread trimming mechanism.

6. The thread trimming control method of a sewing machine according to claim 5, characterized in that: A forced reset arm (52) is also extended from the outer peripheral surface of the thread trimming cam, and the forced reset arm (52) is circumferentially staggered with the thread trimming drive arm (51). A rotatable forced reset ball (64) is installed on the thread trimming drive lever (61), and the forced reset ball (64) can contact and cooperate with the outer peripheral surface of the forced reset arm (52).

7. The thread trimming control method of a sewing machine according to claim 5, characterized in that: The thread trimming mechanism comprises a thread trimming shaft (81) rotatably mounted on a sewing machine bottom plate (110), a first thread trimming crank (82) and a second thread trimming crank (83) both fixed to the thread trimming shaft (81), a thread trimming connecting rod (84), a movable knife frame (85), a movable knife (86) fixed to the movable knife frame (85), and a fixed knife (87) fixed to the sewing machine bottom plate (110), the thread trimming driving connecting rod (63) being hinged to the first thread trimming crank (82), and the two ends of the thread trimming connecting rod (84) being hinged to the second thread trimming crank (83) and the movable knife frame (85) respectively.

8. The thread trimming control method of a sewing machine according to claim 7, characterized in that: The thread trimming mechanism also includes a reset torsion spring sleeved on the thread trimming shaft (81), and two ends of the reset torsion spring are respectively connected to the second thread trimming crank (83) and the sewing machine bottom plate (110).

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