CN111501213B

CN111501213B - Method for adjusting needle distance by lifting and pressing thread of sewing machine

Info

Publication number: CN111501213B
Application number: CN201910097857.2A
Authority: CN
Inventors: 刘强; 管建平; 林晓晓
Original assignee: Jack Sewing Machine Co Ltd
Current assignee: Jack Technology Co Ltd
Priority date: 2019-01-31
Filing date: 2019-01-31
Publication date: 2021-06-04
Anticipated expiration: 2039-01-31
Also published as: CN111501213A

Abstract

The invention relates to the technical field of sewing machines, in particular to a method for adjusting the needle pitch by lifting and pressing a thread trimming pin of a sewing machine, which is mainly characterized in that before sewing is started, a needle pitch adjusting mechanism can be driven to execute the needle pitch adjusting action through a needle pitch adjusting section of a needle pitch adjusting profile surface of a cam, and a required initial needle pitch value is obtained; after sewing is finished, the trimming mechanism can be driven to perform trimming action through the trimming section of the trimming contour surface of the cam, then the presser foot lifting mechanism can be driven to perform presser foot lifting action through the first presser foot lifting section of the presser foot lifting contour surface of the cam, or trimming action is not performed, the presser foot lifting mechanism can be driven to perform presser foot lifting action through the second presser foot lifting section of the presser foot lifting contour surface of the cam, or presser foot lifting action is not performed after trimming action is finished, and direct inversion reset is performed. The three functions of trimming, lifting the presser foot and adjusting the needle pitch are realized by driving one cam by one power part, the structure is simple, and the transmission efficiency is high.

Description

Method for adjusting needle distance by lifting and pressing thread of sewing machine

Technical Field

The invention relates to the technical field of sewing machines, in particular to a method for adjusting the needle pitch of a thread cutting, presser foot lifting and sewing machine.

Background

A sewing machine is a machine that uses one or more sewing threads to form one or more stitches in a fabric, thereby interweaving or stitching one or more layers of material. The sewing machine is generally composed of four parts, namely a feeding device, a base, a transmission and an accessory, and sewing materials are sewn through reasonable cooperation and circular work of the motion of each mechanism.

At present, the sewing machine can use the functions of automatic thread trimming, automatic presser foot lifting and automatic needle distance adjustment in the sewing process. The common mode is that two electromagnets with different powers are used for respectively driving a thread trimming mechanism and a presser foot lifting mechanism to act, so that the functions of automatic thread trimming and automatic presser foot lifting are realized, and in addition, a stepping motor is used for driving a needle pitch adjusting mechanism to act, so that the function of automatic needle pitch adjustment is realized. The driving mode has the defects of complex structure and low transmission efficiency.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for adjusting the needle pitch of a thread cutting, pressure lifting and pressing foot of a sewing machine with high transmission efficiency so as to overcome the defects in the prior art.

In order to solve the technical problems, the invention adopts the following technical scheme: a method for adjusting the needle pitch of a thread trimming, presser foot lifting and sewing machine comprises the following steps: step S1, starting the sewing machine; step S2, the rotating shaft of the power part rotates and resets to the initial position, and the driving cam rotates and resets to the initial position; step S3, determining whether to adjust the stitch length: if the stitch length needs to be adjusted, a rotating shaft of the power part rotates in a stitch length adjusting interval, a stitch length adjusting mechanism is driven to execute the stitch length adjusting action through a stitch length adjusting section of a stitch length adjusting contour surface of the cam, at the moment, the thread cutting mechanism and the presser foot lifting mechanism do not act, when the stitch length is adjusted to a required initial stitch length value, the power part stops rotating, and then the next step S4 is carried out; if the stitch length does not need to be adjusted, directly entering the next step S4; step S4, the sewing machine starts sewing work until the sewing is finished; step S5, judging whether to cut the thread: if the thread cutting is needed, the rotating shaft of the power part rotates anticlockwise from the needle pitch adjusting interval to enter the thread cutting interval, the thread cutting mechanism is driven to execute the thread cutting action through the thread cutting section of the thread cutting outline surface of the cam, at the moment, the presser foot lifting mechanism does not act, and after the thread cutting action is finished, the next step S6 is carried out; if the trimming is not needed, directly entering the next step S6; step S6, judging whether to lift the presser foot: if the presser foot needs to be lifted after the thread trimming action is finished, the rotating shaft of the power part continuously rotates anticlockwise from the thread trimming interval to enter the presser foot lifting interval, the presser foot lifting mechanism is driven to perform the presser foot lifting action through the first presser foot lifting section of the contour surface of the cam, at the moment, the thread trimming mechanism reversely moves and resets under the action of a reset spring, after the presser foot lifting action is finished, the rotating shaft of the power part continuously rotates anticlockwise to enter the needle pitch adjusting interval, the presser foot lifting mechanism resets through the second presser foot lifting section of the contour surface of the cam, the presser foot descends to the initial position, and then the next step S7 is carried out; if the presser foot needs to be lifted under the condition that the thread trimming action is not executed, the rotating shaft of the power part rotates clockwise from the needle pitch adjusting interval to enter the presser foot lifting interval, the second presser foot lifting section of the presser foot lifting contour surface of the cam drives the presser foot lifting mechanism to execute the presser foot lifting action, at the moment, the thread trimming mechanism does not act, after the presser foot lifting action is completed, the rotating shaft of the power part rotates reversely to return to the needle pitch adjusting interval, the presser foot lifting mechanism resets, the presser foot descends to the initial position, and then the next step S7 is executed; if the presser foot does not need to be lifted, the next step S7 is directly carried out; step S7, continuing sewing or reversing the rotating shaft of the power piece to the initial needle pitch value; step S8, judging whether to continue sewing: if yes, go back to step S3; if not, the next step S9 is entered; and step S9, ending sewing.

Preferably, in step S4, when sewing is started, the rotating shaft of the power member rotates clockwise from the stitch adjusting interval into the presser foot lifting interval, and the second presser foot lifting segment of the presser foot lifting profile surface of the cam drives the presser foot lifting mechanism to perform the presser foot lifting action to slightly lift the seam; then the rotating shaft of the power part rotates reversely to the position corresponding to the initial needle pitch value in the needle pitch adjusting interval, and normal sewing is carried out.

Preferably, in step S5, when the rotating shaft of the power member rotates counterclockwise from the stitch adjusting interval to the stitch cutting interval, before entering the stitch cutting interval, the first transition section of the stitch adjusting contour surface of the cam drives the stitch adjusting mechanism to perform the stitch adjusting operation, so that the stitch length transits from the initial stitch length value to 0, at this time, the stitch cutting mechanism and the presser foot lifting mechanism do not operate, and when the stitch length transits to 0, the stitch encryption operation is performed, and then the stitch cutting operation is performed.

Preferably, in step S7, if the thread cutting operation and the presser foot lifting operation are not performed before step S7, the sewing is continued, and the process proceeds to the next step S8; if the presser foot raising operation is performed before step S7, the process proceeds directly to the next step S8; if the trimming operation is performed and the presser foot lifting operation is not performed before step S7, the rotating shaft of the power element is rotated clockwise from the trimming section to the position corresponding to the initial pitch value in the pitch adjustment section in step S7, and at this time, the trimming segment of the trimming contour surface of the cam drives the trimming mechanism to be operated in the reverse direction and reset, and the presser foot lifting mechanism is not operated.

Compared with the prior art, the invention has the remarkable progress that:

the invention relates to a method for adjusting the needle pitch of a thread cutting and presser foot lifting mechanism of a sewing machine, which is characterized in that a power part drives a cam to rotate, and the corresponding thread cutting mechanism, presser foot lifting mechanism or needle pitch adjusting mechanism can be driven to move to execute thread cutting action, presser foot lifting action or needle pitch adjusting action by the angle matching of a thread cutting profile surface, a presser foot lifting profile surface and a needle pitch adjusting profile surface on the cam, namely, three functions of thread cutting, presser foot lifting and needle pitch adjusting are realized by one cam.

Drawings

Fig. 1 is a schematic view of the overall structure of a sewing machine according to an embodiment of the present invention.

FIG. 2 is a schematic structural view of a thread trimming, presser foot lifting and stitch length adjusting device of the sewing machine according to the embodiment of the invention.

Fig. 3 is a schematic view of the cam in the embodiment of the present invention as seen from one direction.

Fig. 4 is a schematic structural view of the cam in the embodiment of the present invention, viewed from another direction.

Fig. 5 is a schematic structural diagram of a thread trimming mechanism, a thread trimming driving crank and a cam in the embodiment of the invention.

Fig. 6 is a schematic structural view of the presser foot lifting mechanism, the presser foot lifting driving crank and the cam in the embodiment of the invention.

FIG. 7 is a schematic view of the needle pitch adjusting mechanism, the needle pitch adjusting driving crank and the cam in the embodiment of the invention.

Fig. 8 is a schematic diagram of the configuration of the shear profile of the cam in an embodiment of the present invention.

Fig. 9 is a schematic structural view of a lift and press foot profile of a cam in an embodiment of the invention.

Fig. 10 is a schematic structural view of a pitch profile of a cam in an embodiment of the present invention.

Fig. 11 is a schematic diagram of three driving sections into which the power member rotates once in the embodiment of the present invention.

Fig. 12 is a schematic view of the cam in the embodiment of the present invention corresponding to three driving sections of one rotation of the power member.

FIG. 13 is a schematic view showing the operation of the thread trimming, presser foot lifting and stitch length adjusting device of the sewing machine according to the embodiment of the present invention.

Wherein the reference numerals are as follows:

1. bottom plate 2, oil pan

3. Power member 30, rotating shaft

31. Support 4, cam

401. Trimming cam 402 and presser foot lifting cam

403. Needle pitch adjusting cam body 404 and arc-shaped limiting part

405. Annular limiting part 41 and trimming contour surface

411. Base circle section 412 for trimming, trimming section

413. Depressed section 42, lift presser foot profile

421. Lift presser foot base circle segment 422, first lift presser foot segment

423. Second lifting presser foot section 43, profile surface for adjusting needle pitch

431. Needle pitch adjusting section 432 and first transition section

433. First arc segment 434, second transition segment

435. Second arc segment 51, trimming drive shaft

52. Trimming driving crank 521 and trimming ball

53. Trimming front crank 54 and trimming crank connecting rod

55. Trimming rear crank 56 and trimming crank shaft

571. Trimming crank 572 and trimming connecting rod

573. Movable knife rest 574 and movable knife

575. Stationary knife 61, lift presser foot drive shaft

62. Lift presser foot drive crank 621, lift presser foot ball

63. Crank 64 and ejector rod for lifting presser foot

71. Needle pitch adjusting drive shaft 72 and needle pitch adjusting drive crank

721. Needle pitch adjusting ball 73 and needle pitch adjusting crank

74. Needle pitch adjusting connecting rod 75 and needle pitch adjusting swing plate seat

76. Connecting rod structure 77 and feeding structure

78. Needle pitch adjusting connecting pin

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings. These embodiments are merely illustrative of the present invention and are not intended to limit the present invention.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.

As shown in fig. 1 to 13, an embodiment of the present invention provides a thread cutting, presser foot lifting and stitch length adjusting device for a sewing machine. The thread trimming, presser foot lifting and needle distance adjusting device of the sewing machine is arranged in the sewing machine and used for achieving the thread trimming function, the presser foot lifting function and the needle distance adjusting function of the sewing machine. For convenience of description, the moving direction of the cloth when the sewing machine sews is defined as a forward direction, and a direction perpendicular to the moving direction of the cloth on a horizontal plane is a left-right direction, and a side close to the head is a left side and a side close to the tail is a right side.

Referring to fig. 1, the sewing machine has a base plate 1 and an oil pan 2, the oil pan 2 is fixed on the base plate 1, and the thread trimming, presser foot lifting and stitch length adjusting device of the sewing machine of the present embodiment is installed on the base plate 1.

Referring to fig. 2, the thread trimming, presser foot lifting and stitch length adjusting device of the sewing machine of the present embodiment includes a power member 3, a cam 4, a thread trimming driving crank 52, a thread trimming mechanism, a presser foot lifting driving crank 62, a presser foot lifting mechanism, a stitch length adjusting driving crank 72 and a stitch length adjusting mechanism.

The power part 3 is fixedly supported on the bottom plate 1 of the sewing machine through the bracket 31, the power part 3 is connected with the cam 4, the power part 3 is provided with a rotating shaft, the cam 4 is fixedly arranged on the rotating shaft of the power part 3, and the rotation of the rotating shaft of the power part 3 drives the cam 4 to synchronously rotate along with the rotating shaft. The angle of the power part 3 driving the cam 4 to rotate is controllable, and preferably, the power part 3 can be a stepping motor or a servo motor, so that the accurate control of the rotation angle of the cam 4 can be realized. Referring to fig. 3 and 4, the cam 4 in this embodiment has a trimming profile surface 41, a presser foot profile surface 42, and a stitch length profile surface 43. Preferably, the presser foot contour surface 42 is located on the outer periphery of the cam 4, and the trimming contour surface 41 and the stitch adjusting contour surface 43 are respectively located on both sides of the cam 4, in this embodiment, the trimming contour surface 41 is located on the left side of the cam 4, and the stitch adjusting contour surface 43 is located on the right side of the cam 4.

Referring to fig. 2 and 5, the trimming ball 521 is disposed on the trimming driving crank 52, and the trimming ball 521 is engaged with the trimming contour surface 41 of the cam 4. The trimming ball 521 may be fixedly mounted on the trimming driving crank 52, or may be rollably mounted on the trimming driving crank 52, and in this embodiment, the trimming ball 521 is preferably rollably mounted on the trimming driving crank 52, so as to reduce the friction between the trimming ball 521 and the trimming contour surface 41 of the cam 4 when the trimming ball 521 is engaged with the trimming contour surface. The thread cutting drive crank 52 is connected to the thread cutting mechanism. When the power part 3 drives the cam 4 to rotate, the trimming contour surface 41 of the cam 4 rotates around the axis of the rotating shaft of the power part 3, the trimming driving crank 52 is driven to swing through the action of the trimming contour surface 41 on the trimming ball 521, and the swinging of the trimming driving crank 52 drives the trimming mechanism to move so as to execute the trimming action.

In the present embodiment, preferably, referring to fig. 2 and 5, the thread cutting mechanism includes a thread cutting drive shaft 51, the thread cutting drive shaft 51 is rotatably supported on the base plate 1, and the thread cutting drive shaft 51 is parallel to the rotation axis of the power member 3. The thread cutting driving crank 52 is fixedly arranged at the right end of the thread cutting driving shaft 51, and the left end of the thread cutting driving shaft 51 is connected with the thread cutting assembly. When the cam 4 drives the trimming driving crank 52 to swing, the trimming driving shaft 51 is driven to rotate by the swinging of the trimming driving crank 52, and the trimming assembly is driven to move by the rotation of the trimming driving shaft 51 to execute the trimming action. Further, the thread trimming mechanism further comprises a thread trimming front crank 53, a thread trimming crank connecting rod 54, a thread trimming rear crank 55 and a thread trimming crank shaft 56, wherein the thread trimming crank shaft 56 is rotatably supported on the bottom plate 1, and the thread trimming crank shaft 56 is parallel to the thread trimming driving shaft 51. One end of the trimming front crank 53 is fixedly arranged at the left end of the trimming driving shaft 51, the other end of the trimming front crank 53 is hinged with one end of the trimming crank connecting rod 54, the other end of the trimming crank connecting rod 54 is hinged with one end of the trimming rear crank 55, the other end of the trimming rear crank 55 is fixedly arranged at the right end of the trimming crank shaft 56, and the left end of the trimming crank shaft 56 is connected with the trimming component. When the thread cutting driving shaft 51 rotates, the thread cutting crank shaft 56 can be driven to rotate along with the rotation of the thread cutting front crank 53, the thread cutting crank connecting rod 54 and the thread cutting rear crank 55, and the rotation of the thread cutting crank shaft 56 drives the thread cutting assembly to move so as to perform thread cutting. The thread trimming component can be a structure capable of realizing thread trimming action in the prior art, and the thread trimming component can be suitable for various structural forms and has the advantage of wide application range. For example, the thread cutting assembly may include a thread cutting crank 571, a thread cutting connecting rod 572, a movable knife holder 573, a movable knife 574, and a fixed knife 575, wherein one end of the thread cutting crank 571 is hinged to the left end of the thread cutting crank 56, the other end of the thread cutting crank 571 is hinged to one end of the thread cutting connecting rod 572, the other end of the thread cutting connecting rod 572 is hinged to the movable knife holder 573, the movable knife 574 is mounted on the movable knife holder 573, and the fixed knife 575 is fixedly mounted on the base plate 1, so that when the thread cutting crank 56 rotates, the movable knife 574 is driven by the transmission of the thread cutting crank 571 and the thread cutting connecting rod 572 to move relative to the fixed knife 575, thereby performing a thread cutting operation. Of course, the structure of the thread cutting assembly is not limited to this single-action knife structure, and a double-action knife structure may be employed.

Referring to fig. 2 and 6, the presser foot lifting driving crank 62 is provided with a presser foot lifting ball 621, and the presser foot lifting ball 621 is matched with the presser foot lifting contour surface 42 of the cam 4. The pressure raising and pressing ball 621 may be fixedly mounted on the pressure raising and pressing pin driving crank 62, or may be rollably mounted on the pressure raising and pressing pin driving crank 62, in this embodiment, the pressure raising and pressing ball 621 is rollably mounted on the pressure raising and pressing pin driving crank 62, so that the friction force between the pressure raising and pressing ball 621 and the pressure raising and pressing pin contour surface 42 of the cam 4 can be reduced. The presser foot lifting drive crank 62 is connected to the presser foot lifting mechanism. When the power member 3 drives the cam 4 to rotate, the presser foot lifting contour surface 42 of the cam 4 rotates along with the axis of the rotating shaft of the power member 3, the presser foot lifting driving crank 62 can be driven to swing through the action of the presser foot lifting contour surface 42 on the presser foot lifting ball 621, and the presser foot lifting mechanism is driven to move by the swinging of the presser foot lifting driving crank 62 to execute the presser foot lifting action. The accurate control of the lifting height of the presser foot can be realized by controlling the rotating angle of the cam 4 by the power part 3.

In the present embodiment, preferably, referring to fig. 2 and 6, the presser foot lifting mechanism includes a presser foot lifting drive shaft 61, a presser foot lifting crank 63 and a push rod 64, the presser foot lifting drive shaft 61 is rotatably supported on the bottom plate 1, and the presser foot lifting drive shaft 61 is parallel to the rotation axis of the power member 3, in the present embodiment, the presser foot lifting drive shaft 61 is a shaft sleeve axially penetrating through. The pressure lifting and foot driving crank 62 is fixedly arranged at the left end of the pressure lifting and foot driving shaft 61, one end of the pressure lifting and foot crank 63 is fixedly arranged at the right end of the pressure lifting and foot driving shaft 61, the other end of the pressure lifting and foot crank 63 is abutted against the bottom end of the ejector rod 64, and the top end of the ejector rod 64 is connected with the pressure lifting and foot assembly. When the cam 4 drives the presser foot lifting driving crank 62 to swing, the presser foot lifting driving shaft 61 is driven by the swing of the presser foot lifting driving crank 62 to rotate along with the cam, the presser foot lifting driving shaft 61 rotates to drive the presser foot lifting crank 63 to swing along with the cam, so that the presser foot lifting crank 63 pushes the ejector rod 64 to move upwards, the movement of the ejector rod 64 drives the presser foot lifting assembly to move, and the presser foot lifting action is executed. The presser foot lifting component can be a structure capable of realizing the action of lifting the presser foot in the prior art. Meanwhile, the presser foot lifting mechanism of the embodiment does not interfere the installation of the existing knee rest presser foot lifting, and can meet the requirements of different users at the same time. Preferably, a buffer pad can be arranged between the presser foot lifting crank 63 and the mandril 64, so as to play a role of buffering, and reduce vibration and noise in the presser foot lifting process.

Referring to fig. 2 and 7, the needle pitch driving crank 72 is provided with a needle pitch ball 721, and the needle pitch ball 721 is engaged with the needle pitch contour surface 43 of the cam 4. The pitch ball 721 may be fixedly mounted on the pitch drive crank 72 or rollably mounted on the pitch drive crank 72, and in this embodiment, the pitch ball 721 is preferably rollably mounted on the pitch drive crank 72 to reduce the friction between the pitch ball 721 and the pitch profile surface 43 of the cam 4 when the pitch ball 721 is engaged with the pitch profile surface. The needle pitch drive crank 72 is connected to the needle pitch mechanism. When the power member 3 drives the cam 4 to rotate, the needle adjusting profile surface 43 of the cam 4 rotates around the axis of the rotating shaft of the power member 3, the needle adjusting driving crank 72 is driven to swing through the action of the needle adjusting profile surface 43 on the needle adjusting ball 721, and the swinging of the needle adjusting driving crank 72 drives the needle adjusting mechanism to move so as to execute the needle adjusting action. The accurate adjustment of the needle pitch can be realized by controlling the rotating angle of the cam 4 by the power part 3.

In the present embodiment, preferably, referring to fig. 2 and 7, the needle pitch adjusting mechanism includes a needle pitch adjusting driving shaft 71, a needle pitch adjusting crank 73, a needle pitch adjusting connecting rod 74 and a needle pitch adjusting swing plate seat 75, the needle pitch adjusting driving shaft 71 is rotatably supported on the bottom plate 1, and the needle pitch adjusting driving shaft 71 is parallel to the rotating shaft of the power member 3. The needle pitch adjusting driving crank 72 is fixedly arranged at the left end of the needle pitch adjusting driving shaft 71, one end of the needle pitch adjusting crank 73 is fixedly arranged at the right end of the needle pitch adjusting driving shaft 71, the other end of the needle pitch adjusting crank 73 is hinged with one end of the needle pitch adjusting connecting rod 74 through a needle pitch adjusting connecting pin 78, the other end of the needle pitch adjusting connecting rod 74 is hinged with a needle pitch adjusting swing plate seat 75, and the needle pitch adjusting swing plate seat 75 is connected with a needle pitch adjusting assembly. When the cam 4 drives the needle pitch adjusting driving crank 72 to swing, the needle pitch adjusting driving shaft 71 is driven to rotate by the swinging of the needle pitch adjusting driving crank 72, when the needle pitch adjusting driving shaft 71 rotates, the needle pitch adjusting swinging plate seat 75 can be driven to rotate by the transmission belts of the needle pitch adjusting crank 73 and the needle pitch adjusting connecting rod 74, and the needle pitch adjusting assembly is driven to move by the rotation of the needle pitch adjusting swinging plate seat 75 to execute the needle pitch adjusting action. The stitch length adjusting assembly may be a link structure 76 and a feeding structure 77 that are capable of performing a stitch length adjusting operation in the prior art.

The sewing machine trimming pressure foot lifting and needle distance adjusting device of the embodiment drives the cam 4 to rotate by the power part 3, and the corresponding trimming mechanism, the pressure foot lifting mechanism or the needle distance adjusting mechanism can be driven to move through the angle matching of the trimming profile surface 41, the pressure foot lifting profile surface 42 and the needle distance adjusting profile surface 43 on the cam 4 to execute trimming action, pressure foot lifting action or needle distance adjusting action, namely three functions of trimming, pressure foot lifting and needle distance adjusting are realized by the cam 4.

In this embodiment, the power member 3 may be connected to a controller (not shown), and the controller controls the power member 3 to start or stop rotating according to the operation requirement of the sewing machine, and controls the rotating direction and rotating angle of the power member 3, so as to control the matching state between the trimming profile surface 41 of the cam 4 and the trimming ball 521, the matching state between the presser foot lifting profile surface 42 and the presser foot lifting ball 621, and the matching state between the stitch length adjusting profile surface 43 and the stitch length adjusting ball 721, thereby realizing the precise control of the trimming operation, the presser foot lifting operation, and the stitch length adjusting operation. The controller can be a main controller of the existing sewing machine, such as a PLC controller or a singlechip.

Referring to fig. 3 and 4, the cam 4 in this embodiment includes a thread trimming cam body 401, a presser foot lifting cam body 402, and a needle adjustment cam body 403, the presser foot lifting cam body 402 is a disk-shaped cam, and the thread trimming cam body 401 and the needle adjustment cam body 403 are respectively located on the left and right side surfaces of the presser foot lifting cam body 402 and are all coaxially arranged with the presser foot lifting cam body 402, that is, the thread trimming cam body 401, the presser foot lifting cam body 402, and the needle adjustment cam body 403 rotate around the same rotation center. Preferably, the trimming cam body 401, the presser foot lifting cam body 402 and the needle pitch adjusting cam body 403 are an integrally formed integral piece, that is, the cam 4 is an integrally formed integral piece. Of course, the trimming cam body 401, the presser foot lifting cam body 402 and the needle pitch adjusting cam body 403 may be coaxially arranged as separate members.

Referring to fig. 3 and 8, the outer peripheral surface of the trimming cam body 401 is a trimming contour surface 41, and the trimming contour surface 41 includes a trimming base circle segment 411, a trimming segment 412 and a recessed segment 413 which are sequentially connected to form a circle along the circumferential direction. The trimming base circle segment 411 is an arc segment concentrically arranged with the rotation center of the trimming cam body 401, the distance between the trimming segment 412 and the rotation center of the trimming cam body 401 gradually increases, and the concave segment 413 protrudes toward the inside of the trimming cam body 401, so that the end of the trimming segment 412 is the highest point of the trimming contour surface 41. During one rotation of the cam 4, the trimming ball 521 is in contact engagement with the trimming base circle segment 411 and the trimming segment 412 of the trimming contour surface 41. When the trimming ball 521 is located at the trimming base circle segment 411, the position of the trimming ball 521 is kept unchanged, the trimming driving crank 52 executes an idle stroke, and the trimming mechanism does not act. After the trimming ball 521 enters the trimming section 412 from the trimming base circle section 411, the trimming driving crank 52 gradually swings under the driving of the trimming section 412 along with the rotation of the cam 4, the trimming mechanism is driven to perform the trimming action until the trimming ball 521 reaches the end of the trimming section 412, and the trimming action is completed. After the trimming operation is completed, if the cam 4 continues to rotate, the trimming ball 521 will cross the end of the trimming segment 412 and the concave segment 413 to reach the trimming base circle segment 411, in this process, the trimming driving crank 52 and the trimming mechanism can reversely move and reset under the action of the trimming mechanism reset spring, which is the prior art and is not described herein again. After the thread cutting operation is completed, if the cam 4 rotates reversely, the thread cutting ball 521 will move reversely along the thread cutting section 412, and drive the thread cutting driving crank 52 and the thread cutting mechanism to reset.

Preferably, the cam 4 is provided with an arc-shaped limiting portion 404, the arc-shaped limiting portion 404 is arranged at the outer edge of the left side surface of the presser foot lifting cam body 402, the inner side surface of the arc-shaped limiting portion 404 is arranged opposite to the trimming section 412 of the trimming contour surface 41 at an interval, a track groove is formed between the inner side surface of the arc-shaped limiting portion 404 (i.e. the side surface of the arc-shaped limiting portion 404 opposite to the trimming contour surface 41) and the trimming section 412, the trimming ball 521 moves along the track groove when passing through the trimming section 412, the arc-shaped limiting portion 404 can limit the movement of the trimming ball 521 when passing through the trimming section 412, the trimming ball 521 rolls along the trimming section 412, and thus the accurate execution of the trimming action is ensured. Preferably, referring to fig. 8, a portion of the trimming section 412 near the end of the trimming section 412 is an arc section AB, an inner side surface of the arc-shaped limiting portion 404 opposite to the arc section AB is an arc section CD, and the arc section CD and the arc section AB are concentric arcs, so as to optimize the limiting effect.

In a specific embodiment, the trimming line segment 412 is formed by sequentially connecting an arc with a radius of 40mm, a straight line with a length of 3.11mm, and an arc with a radius of 8.97mm, wherein the arc segment AB has a radius of 8.97mm, and the arc segment CD of the arc-shaped limiting part 404 has a radius of 14 mm.

Referring to fig. 4 and 9, the outer circumferential surface of the presser foot lifting cam body 402 is a presser foot lifting contour surface 42, and the presser foot lifting contour surface 42 includes a presser foot lifting base circular section 421, a first presser foot lifting section 422 and a second presser foot lifting section 423 which are sequentially connected in a circumferential direction to form a circle. The presser foot lifting base circle section 421 is a circular arc section concentrically arranged with the rotation center of the presser foot lifting cam body 402, the first presser foot lifting section 422 and the second presser foot lifting section 423 are symmetrically arranged, and the distances between the first presser foot lifting section 422 and the second presser foot lifting section 423 and the rotation center of the presser foot lifting cam body 402 are gradually increased and are intersected at the tail ends, so that the intersection point of the first presser foot lifting section 422 and the second presser foot lifting section 423 is the highest point of the presser foot lifting contour surface 42. During one rotation of the cam 4, the presser foot lifting ball 621 is in contact fit with the presser foot lifting base circle section 421, the first presser foot lifting section 422 and the second presser foot lifting section 423. When the presser foot lifting ball 621 is located at the presser foot lifting base circle section 421, the position of the presser foot lifting ball 621 is kept unchanged, the presser foot lifting driving crank 62 executes an idle stroke, and the presser foot lifting mechanism does not act. When the presser foot lifting ball 621 enters the first presser foot lifting section 422 from the presser foot lifting base circle section 421 or enters the second presser foot lifting section 423 from the presser foot lifting base circle section 421, the presser foot driving crank 62 is driven by the first presser foot lifting section 422 or the second presser foot lifting section 423 to gradually swing along with the rotation of the cam 4, the presser foot lifting mechanism is driven to perform the presser foot lifting action until the presser foot lifting ball 621 reaches the intersection point of the first presser foot lifting section 422 and the second presser foot lifting section 423, the presser foot lifting height reaches the maximum value, and in the process, the presser foot lifting height can be controlled by controlling the rotation angle of the cam 4. Through the first presser foot lifting section 422 and the second presser foot lifting section 423 which are symmetrically arranged, the cam 4 can rotate towards the positive direction and the negative direction to realize the presser foot lifting action, so that the cam 4 can continuously rotate to execute the presser foot lifting action after rotating towards one direction to execute the thread trimming action (for example, rotating towards the anticlockwise direction to enable the presser foot lifting ball 621 to enter the first presser foot lifting section 422 from the presser foot lifting base circle section 421), or the cam 4 rotates towards the other direction to execute the presser foot lifting action (for example, rotating towards the clockwise direction to enable the presser foot lifting ball 621 to enter the second presser foot lifting section 423 from the presser foot lifting base circle section 421 under the condition of not executing the thread trimming action). Under the condition that the presser foot lifting action is continuously rotated after the thread trimming action is finished, the presser foot lifting action is finished, and after the related operation is finished, the cam 4 can be continuously rotated, the presser foot lifting ball 621 enters the second presser foot lifting section 423 from the first presser foot lifting section 422 and moves towards the direction of the presser foot lifting base circle section 421 along the second presser foot lifting section 423, and the presser foot lifting driving crank 62 and the presser foot lifting mechanism can be driven to reversely act and reset, so that the presser foot is lowered to the initial position. When the presser foot lifting action is executed under the condition that the thread trimming action is not executed, the presser foot lifting action is completed, and after the relevant operation is completed, the cam 4 can be rotated reversely, the presser foot lifting ball 621 moves reversely along the second presser foot lifting section 423, and the presser foot lifting driving crank 62 and the presser foot lifting mechanism can be driven to perform reverse action reset, so that the presser foot is lowered to the initial position.

In one specific embodiment, the first presser foot section 422 and the second presser foot section 423 are each formed by connecting an arc of a radius of 37.64mm and an arc of a radius of 22 mm.

Referring to fig. 4, the outer peripheral surface of the needle pitch cam body 403 is a needle pitch contour surface 43, and during one rotation of the cam 4, the needle pitch balls 721 are always in contact with the needle pitch contour surface 43, and influence is exerted on the needle pitch by the needle pitch contour surface 43. In this embodiment, preferably, the cam 4 is provided with an annular limiting portion 405, the annular limiting portion 405 is disposed at an outer edge of the right side surface of the presser foot lifting cam body 402, an inner circumferential surface of the annular limiting portion 405 is disposed opposite to the needle pitch adjusting profile surface 43 at an interval, an annular track groove is formed between the inner circumferential surface of the annular limiting portion 405 and the needle pitch adjusting profile surface 43, the needle pitch adjusting ball 721 moves along the annular track groove, the annular limiting portion 405 can limit the movement of the needle pitch adjusting ball 721, and the needle pitch adjusting ball 721 is ensured to move along the needle pitch adjusting profile surface 43, thereby ensuring accurate execution of the needle pitch adjusting action. Preferably, the center of the right side surface of the lifting and pressing foot cam body 402 is recessed inwards, so that the outer edge of the right side surface of the lifting and pressing foot cam body 402 forms the annular limiting part 405, the outer peripheral surface of the annular limiting part 405 is the outer peripheral surface of the lifting and pressing foot cam body 402, namely the lifting and pressing foot profile surface 42, and the needle spacing cam body 403 is arranged at the central recess of the right side surface of the lifting and pressing foot cam body 402 and has a gap with the inner peripheral surface of the annular limiting part 405, so as to form the annular track groove.

Referring to fig. 10, the needle pitch adjusting contour surface 43 includes a needle pitch adjusting section 431, a first transition section 432, a first circular arc section 433, a second transition section 434, and a second circular arc section 435, which are sequentially connected in a circumferential direction to form a circle. The distance between the needle pitch adjusting section 431 and the rotation center of the needle pitch adjusting cam body 403 is gradually increased, the corresponding needle pitch is gradually reduced from the maximum value + N to the minimum value-N, N is a positive number, for example, N is 5mm, and backstitch can be realized in the range of (-N, 0) needle pitch. The distance between the first transition section 432 and the center of rotation of the pitch cam body 403 gradually decreases, and the corresponding pitch gradually increases from the minimum value-N to 0. The end of the gauge adjustment section 431, i.e. the intersection of the gauge adjustment section 431 and the first transition section 432, is the highest point of the gauge adjustment contour surface 43. The first arc segment 433 is an arc segment concentrically disposed with the rotation center of the needle pitch adjusting cam body 403, and the corresponding needle pitch is maintained at 0. The distance between the second transition 434 and the center of rotation of the pitch cam body 403 gradually decreases, and the corresponding pitch gradually increases from 0 to a maximum value of + N. The second circular arc segment 435 is a circular arc segment concentrically disposed with the rotation center of the needle pitch adjusting cam body 403, and the corresponding needle pitch is maintained at the maximum value + N. The needle pitch adjusting section 431 is a main action section of the needle pitch adjusting contour surface 43, and can realize the adjustment of the working needle pitch of the sewing machine within the range of (-N, + N) needle pitch. When the pitch adjusting ball 721 is located at the pitch adjusting section 431, the pitch adjusting driving crank 72 swings under the driving of the pitch adjusting section 431 along with the rotation of the cam 4, drives the pitch adjusting mechanism to perform the pitch adjusting operation, so that the pitch reaches the required value, and then starts the sewing. After sewing is finished, the thread cutting action or the presser foot lifting action can be carried out according to the requirement. Before the thread trimming operation, the pitch adjusting ball 721 passes through the end of the pitch adjusting section 431 and the first transition section 432 to reach the end of the first transition section 432, so that the pitch is adjusted to 0 (approximately +0.5mm), and the encrypted stitch operation can be performed, and therefore, the first transition section 432 is also an action section of the pitch adjusting profile surface 43 for adjusting the pitch. When the thread cutting action or the presser foot lifting action is performed, the stitch adjusting ball 721 can enter the first arc section 433 from the first transition section 432 and then enter the second transition section 434 to perform the thread cutting action and the presser foot lifting action in sequence, and the stitch adjusting ball 721 can also enter the second arc section 435 from the stitch adjusting section 431 to perform the presser foot lifting action directly. When the stitch length adjusting ball 721 is located at the first arc section 433, the second transition section 434 or the second arc section 435, the stitch length will change correspondingly with the movement of the stitch length adjusting ball 721 along the stitch length adjusting contour surface 43, but since the sewing is stopped, the change of the stitch length will not affect and interfere with the trimming and presser foot lifting actions.

In a specific embodiment, the pitch adjustment section 431 is formed by connecting a circular arc with a radius of 252.31mm and a circular arc with a radius of 9.47mm, wherein the circular arc with a radius of 252.31mm gradually transitions from a maximum value + N to a 0 pitch, the circular arc with a radius of 9.47mm gradually transitions from a 0 pitch to a minimum value-N, and the circular arc with a radius of 9.47mm has a chord length of 9.72 mm. The first transition section 432 is formed by connecting an arc with a radius of 9.47mm and a straight line with a length of 7.51 mm. The radius of the first circular arc segment 433 is 17.8 mm. The second transition 434 is formed by connecting an arc of a circle with a radius of 9.97mm and a straight line with a length of 6.07 mm. The second arc segment 435 has a radius of 14.9 mm.

Referring to fig. 11, in the present embodiment, the rotating shaft 30 of the power member 3 is divided into three driving sections, namely, a stitch adjusting section a, a trimming section b and a presser foot lifting section c, wherein the presser foot lifting section c is divided into a first presser foot lifting section c1 and a second presser foot lifting section c2 in equal halves. Correspondingly, referring to fig. 12, the stitch adjusting section a corresponds to the stitch adjusting section 431 and the first transition section 432 of the stitch adjusting profile surface 43, the trimming section b corresponds to the trimming section 412 of the trimming profile surface 41, and the presser foot lifting section c corresponds to the first presser foot lifting section 422 and the second presser foot lifting section 423 of the presser foot lifting profile surface 42, wherein the first presser foot lifting section c1 corresponds to the first presser foot lifting section 422, and the second presser foot lifting section c2 corresponds to the second presser foot lifting section 423. Herein, the rotating direction of the rotating shaft 30 of the power unit 3 is based on the view from the front of the head of the sewing machine.

In this embodiment, the matching relationship of the angles between the trimming contour surface 41, the presser foot lifting contour surface 42 and the stitch adjusting contour surface 43, that is, the relative positions of the three, should satisfy: when the rotating shaft 30 of the power part 3 is located in the needle distance adjusting interval a, the needle distance adjusting ball 721 is located in the needle distance adjusting section 431 or the first transition section 432 of the needle distance adjusting contour surface 43, the needle distance adjusting section 431 or the first transition section 432 can drive the needle distance adjusting driving crank 72 to swing, the needle distance adjusting mechanism is driven to execute the needle distance adjusting action, and the required needle distance is obtained, at this time, the trimming ball 521 is located in the trimming base circle section 411 of the trimming contour surface 41, the trimming driving crank 52 executes the idle stroke, the trimming mechanism does not operate, meanwhile, the presser foot lifting ball 621 is located in the presser foot lifting base circle section 421 of the presser foot contour surface 42, the presser foot lifting driving crank 62 executes the idle stroke, and the presser foot lifting mechanism does not operate; when the rotating shaft 30 of the power member 3 is located in the trimming interval b, the trimming ball 521 is located in the trimming section 412 of the trimming contour surface 41, and the trimming section 412 can drive the trimming driving crank 52 to swing to drive the trimming mechanism to perform trimming, at this time, the stitch adjusting ball 721 is located in the first arc section 433, so that the trimming is not interfered, meanwhile, the presser foot lifting ball 621 is located in the presser foot lifting base circle section 421 of the presser foot lifting contour surface 42, the presser foot lifting driving crank 62 performs idle stroke, and the presser foot lifting mechanism does not operate; when the rotating shaft 30 of the power member 3 is located in the presser foot lifting interval c, the presser foot lifting ball 621 is located in the first presser foot lifting section 422 or the second presser foot lifting section 423 of the presser foot contour surface 42, the presser foot lifting driving crank 62 can be driven by the first presser foot lifting section 422 or the second presser foot lifting section 423 to swing, the presser foot lifting mechanism is driven to execute the presser foot lifting action, at this time, the stitch adjusting ball 721 is located in the second transition section 434 or the second arc section 435, the presser foot lifting action is not interfered, meanwhile, the trimming ball 521 is located in the trimming base circle section 411 of the trimming contour surface 41, the trimming driving crank 52 executes the idle stroke, and the trimming mechanism does not operate. Therefore, the purposes that the thread cutting action, the presser foot lifting action and the needle pitch adjusting action do not interfere with each other are achieved.

Based on above-mentioned sewing machine trimming lifts presser foot roll adjustment device, this embodiment still provides a sewing machine, and the sewing machine of this embodiment includes the above-mentioned sewing machine trimming of this embodiment lifts presser foot roll adjustment device.

Based on the above device for adjusting the needle distance by lifting the thread trimming and pressing foot of the sewing machine, the present embodiment further provides a method for adjusting the needle distance by lifting the thread trimming and pressing foot of the sewing machine, that is, a working method of the sewing machine adopting the device for adjusting the needle distance by lifting the thread trimming and pressing foot of the sewing machine of the present embodiment, referring to fig. 13, the method specifically includes the following steps:

step S1, starting the sewing machine.

In step S2, the controller controls the rotary shaft 30 of the power member 3 to rotate and return to the initial position, and the drive cam 4 rotates and returns to the initial position. In this initial position, the device is in a default parameter state set by the controller: the rotating shaft 30 of the power member 3 is located at a default angle in the stitch length adjustment interval a, the stitch length adjusting ball 721 is located at a default position on the stitch length adjustment section 431 of the stitch length adjustment contour surface 43, the stitch length is a default value corresponding to the default position in the range of (-N, + N) stitch length, the trimming ball 521 is located at the trimming base circle section 411 of the trimming contour surface 41, and the presser foot lifting ball 621 is located at the presser foot lifting base circle section 421 of the presser foot lifting contour surface 42.

And step S3, judging whether the stitch length is adjusted, namely judging whether the default stitch length needs to be adjusted to obtain the required initial stitch length value. If the stitch length is required to be adjusted, a stitch length adjusting signal can be manually input from a control panel of the sewing machine, the controller transmits the stitch length adjusting signal to the power member, the controller controls the rotating shaft 30 of the power member 3 to rotate in the stitch length adjusting section a according to the stitch length adjusting signal, so that the stitch length adjusting ball 721 moves along the stitch length adjusting section 431 of the stitch length adjusting contour surface 43 to drive the stitch length adjusting driving crank 72 to swing, and drive the stitch length adjusting mechanism to perform the stitch length adjusting action, when the stitch length is adjusted to the required initial stitch length value in the (-N, + N) stitch length range, namely, the parameter requirement of the stitch length adjusting signal is met, the controller controls the rotating shaft 30 of the power member 3 to stop rotating, the stitch length adjustment is completed, and then the next step S4 is performed. In the stitch length adjusting process, the trimming ball 521 is located at the trimming base circle segment 411 of the trimming contour surface 41, the trimming driving crank 52 executes an idle stroke, the presser foot lifting ball 621 is located at the presser foot lifting base circle segment 421 of the presser foot lifting contour surface 42, the presser foot lifting driving crank 62 executes an idle stroke, and neither the trimming mechanism nor the presser foot lifting mechanism is operated. If the stitch length adjustment is not required, the process proceeds directly to the next step S4.

Step S4, the sewing machine starts the sewing work until the sewing is finished. Preferably, when the sewing starts, the controller controls the rotating shaft 30 of the power part 3 to rotate clockwise from the stitch adjusting interval a to enter a second presser foot lifting interval c2 in the presser foot lifting interval c, and rotate within a small angle in the second presser foot lifting interval c2, so that the presser foot lifting ball 621 enters a second presser foot lifting section 423 from the presser foot lifting base circle segment 421, and runs a small distance along the second presser foot lifting section 423, the presser foot lifting driving crank 62 is driven to perform a small-amplitude presser foot lifting action, and the acting force is transmitted to the presser foot through the presser foot lifting mechanism, so that the presser foot pressure during sewing can be controlled, the effect of slightly lifting the sewing is achieved, the bad working condition that the sewing and the thread breaking occur due to the dead pressing of the presser foot is avoided, and the sewing and thread breaking rate is effectively reduced. In the process, the pitch adjusting ball 721 leaves the pitch adjusting section 431 and enters the second circular arc section 435, the pitch is maintained at the maximum value + N, the trimming ball 521 is located at the trimming base circular section 411 of the trimming contour surface 41, the trimming driving crank 52 performs an idle stroke, and the trimming mechanism does not act. Then, the controller controls the rotating shaft 30 of the power member 3 to rotate counterclockwise back to the needle pitch adjusting section a, so that the needle pitch adjusting ball 721 returns to the position of the needle pitch adjusting section 431 corresponding to the initial needle pitch value, the presser foot lifting ball 621 returns to the presser foot lifting base circle section 421, and then the rotating shaft 30 of the power member 3 stops rotating and normal sewing is started until the sewing is completed.

And step S5, after the sewing is finished, judging whether to cut the thread. If the thread cutting is needed, the controller can control the rotating shaft 30 of the power member 3 to rotate anticlockwise from the stitch adjusting interval a to the thread cutting interval b. In the rotating process, the stitch length adjusting ball 721 firstly passes through the end of the stitch length adjusting section 431 and the first transition section 432 to reach the end of the first transition section 432, at this time, the stitch length is transited to 0 (which may be approximately +0.5mm), and a caulking seam (such as a caulking seam of 2 needles) may be performed, in the process, the trimming ball 521 is still located at the trimming base circle section 411 of the trimming profile surface 41, the trimming driving crank 52 performs an idle stroke, the trimming mechanism does not operate, the presser foot lifting ball 621 is still located at the presser foot lifting base circle section 421 of the presser foot lifting profile surface 42, the presser foot lifting driving crank 62 performs an idle stroke, and the presser foot lifting mechanism does not operate. After the encryption seam is finished, the controller controls the rotating shaft 30 of the power member 3 to continue to rotate counterclockwise to enter the trimming section b, so that the trimming ball 521 enters the trimming section 412 from the trimming base circle section 411, the trimming driving crank 52 and the trimming mechanism start to perform the trimming action until the trimming ball 521 reaches the end of the trimming section 412, the trimming action is finished, and then the next step S6 is carried out. During the thread trimming process, the needle pitch adjusting ball 721 moves in the first arc section 433, the needle pitch is kept to be 0, the presser foot lifting ball 621 is still positioned at the presser foot lifting base circle section 421 of the presser foot lifting contour surface 42, the presser foot lifting driving crank 62 executes the idle stroke, and the presser foot lifting mechanism does not operate. If no trimming is required, the process proceeds directly to the next step S6.

And step S6, judging whether the presser foot is lifted. If the presser foot is required to be lifted, a presser foot lifting signal can be transmitted to the power part by the controller, the controller controls the rotating shaft 30 of the power part 3 to rotate to the presser foot lifting interval c according to the presser foot lifting signal, the presser foot lifting ball 621 enters the first presser foot lifting section 422 or the second presser foot lifting section 423 from the presser foot lifting base circle section 421, and the presser foot lifting driving crank 62 and the presser foot lifting mechanism are driven to carry out the presser foot lifting action. Specifically, the presser foot lifting action is divided into two situations: the presser foot is lifted under the condition of not executing the thread trimming action and the presser foot is lifted after the thread trimming action is finished.

If the presser foot needs to be lifted without executing the thread trimming operation, the controller can control the rotating shaft 30 of the power part 3 to rotate clockwise from the stitch adjusting interval a to enter a second presser foot lifting interval c2 in the presser foot lifting interval c, so that the presser foot lifting ball 621 enters a second presser foot lifting section 423 from the presser foot lifting base circle section 421, the second presser foot lifting section 423 drives the presser foot lifting driving crank 62 and the presser foot lifting mechanism to execute the presser foot lifting operation, and when the presser foot is lifted to a required height, the controller controls the rotating shaft 30 of the power part 3 to stop rotating, the presser foot lifting operation is completed, and then the related operation can be manually performed. In the process, the pitch adjusting ball 721 leaves the pitch adjusting section 431 and enters the second circular arc section 435, the pitch is maintained at the maximum value + N, the trimming ball 521 is located at the trimming base circular section 411 of the trimming contour surface 41, the trimming driving crank 52 performs an idle stroke, and the trimming mechanism does not act. After the manual operation is finished, the controller controls the rotating shaft 30 of the power member 3 to rotate anticlockwise to return from the second presser foot lifting interval c2 to the needle pitch adjusting interval a, the presser foot lifting ball 621 returns from the second presser foot lifting section 423 to the presser foot lifting base circle section 421, and drives the presser foot lifting driving crank 62 and the presser foot lifting mechanism to reset, so that the presser foot descends to the initial position, the needle pitch adjusting ball 721 returns from the second circular arc section 435 to the needle pitch adjusting section 431, and then the next step S7 is performed.

If the presser foot needs to be lifted after the thread trimming action is finished, the rotating shaft 30 of the power part 3 can be controlled by the controller to continuously rotate anticlockwise, the thread trimming interval b enters a first presser foot lifting interval c1 in the presser foot lifting interval c, the presser foot lifting ball 621 enters a first presser foot lifting section 422 from a presser foot lifting base circle section 421, the presser foot lifting driving crank 62 and the presser foot lifting mechanism are driven by the first presser foot lifting section 422 to execute the presser foot lifting action, and when the presser foot is lifted to a required height, the controller controls the rotating shaft 30 of the power part 3 to stop rotating, the presser foot lifting action is finished, and then related operations (such as cloth taking out) can be carried out manually. In the process, the needle pitch adjusting ball 721 enters the second transition section 434 from the first circular arc section 433, when the pressure lifting and pressing ball 621 reaches the highest point of the first pressure lifting and pressing section 422, the needle pitch adjusting ball 721 reaches the tail end of the second transition section 434, and the needle pitch is transited from 0 to the maximum value + N; the thread cutting ball 521 crosses the end of the thread cutting segment 412 and the concave segment 413 to reach the thread cutting base circle segment 411, and simultaneously, the thread cutting driving crank 52 and the thread cutting mechanism are reversely moved and reset under the action of the thread cutting mechanism reset spring. After the manual operation is finished, the controller controls the rotating shaft 30 of the power part 3 to continue to rotate anticlockwise, the pressure foot lifting ball 621 enters the pressure foot lifting base circle section 421 through the second pressure foot lifting interval c2, the pressure foot lifting ball 621 drives the pressure foot lifting driving crank 62 and the pressure foot lifting mechanism to reset, the pressure foot descends to the initial position, the needle distance adjusting ball 721 enters the needle distance adjusting section 431 through the second circular arc section 435, and the next step S7 is then performed.

If the presser foot does not need to be lifted, the process proceeds to the next step S7.

In step S7, the controller controls the rotating shaft 30 of the power member 3 to rotate reversely to the original gauge value. If the thread cutting operation and the presser foot lifting operation are not performed before step S7, the sewing is continued, and the process proceeds to the next step S8. If the presser foot raising operation is performed before step S7, the process proceeds directly to the next step S8. If the thread trimming operation is performed and the presser foot lifting operation is not performed before step S7, the controller controls the rotating shaft 30 of the power element 3 to rotate clockwise in step S7, and the thread trimming section b to rotate back to the pitch adjustment section a, and the pitch adjustment ball 721 is returned to the position where the pitch adjustment section 431 corresponds to the required pitch value, and after the pitch is adjusted to the required pitch value, the controller controls the rotating shaft 30 of the power element 3 to stop rotating, and the process proceeds to next step S8. In the process, the trimming ball 521 moves reversely along the trimming contour surface 41, returns to the trimming base circle segment 411 from the trimming segment 412, drives the trimming driving crank 52 and the trimming mechanism to reset, the presser foot lifting ball 621 is located at the presser foot lifting base circle segment 421 of the presser foot lifting contour surface 42, the presser foot lifting driving crank 62 executes an idle stroke, and the presser foot lifting mechanism does not operate.

And step S8, judging whether to continue sewing, if so, returning to step S3, and if not, entering the next step S9.

And step S9, ending sewing.

The above description is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and substitutions can be made without departing from the technical principle of the present invention, and these modifications and substitutions should also be regarded as the protection scope of the present invention.

Claims

1. A method for adjusting the needle pitch of a thread trimming, presser foot lifting and sewing machine is characterized by comprising the following steps:

step S1, starting the sewing machine;

step S2, the rotating shaft of the power part rotates and resets to the initial position, and the driving cam rotates and resets to the initial position;

step S3, determining whether to adjust the stitch length: if the stitch length needs to be adjusted, a rotating shaft of the power part rotates in a stitch length adjusting interval, a stitch length adjusting mechanism is driven to execute the stitch length adjusting action through a stitch length adjusting section of a stitch length adjusting contour surface of the cam, at the moment, the thread cutting mechanism and the presser foot lifting mechanism do not act, when the stitch length is adjusted to a required initial stitch length value, the power part stops rotating, and then the next step S4 is carried out; if the stitch length does not need to be adjusted, directly entering the next step S4;

step S4, the sewing machine starts sewing work until the sewing is finished;

step S5, judging whether to cut the thread: if the thread cutting is needed, the rotating shaft of the power part rotates anticlockwise from the needle pitch adjusting interval to enter the thread cutting interval, the thread cutting mechanism is driven to execute the thread cutting action through the thread cutting section of the thread cutting outline surface of the cam, at the moment, the presser foot lifting mechanism does not act, and after the thread cutting action is finished, the next step S6 is carried out; if the trimming is not needed, directly entering the next step S6;

step S6, judging whether to lift the presser foot: if the presser foot needs to be lifted after the thread trimming action is finished, the rotating shaft of the power part continuously rotates anticlockwise from the thread trimming interval to enter the presser foot lifting interval, the presser foot lifting mechanism is driven to perform the presser foot lifting action through the first presser foot lifting section of the contour surface of the cam, at the moment, the thread trimming mechanism reversely moves and resets under the action of a reset spring, after the presser foot lifting action is finished, the rotating shaft of the power part continuously rotates anticlockwise to enter the needle pitch adjusting interval, the presser foot lifting mechanism resets through the second presser foot lifting section of the contour surface of the cam, the presser foot descends to the initial position, and then the next step S7 is carried out;

if the presser foot needs to be lifted under the condition that the thread trimming action is not executed, the rotating shaft of the power part rotates clockwise from the needle pitch adjusting interval to enter the presser foot lifting interval, the second presser foot lifting section of the presser foot lifting contour surface of the cam drives the presser foot lifting mechanism to execute the presser foot lifting action, at the moment, the thread trimming mechanism does not act, after the presser foot lifting action is completed, the rotating shaft of the power part rotates reversely to return to the needle pitch adjusting interval, the presser foot lifting mechanism resets, the presser foot descends to the initial position, and then the next step S7 is executed; if the presser foot does not need to be lifted, the next step S7 is directly carried out;

step S7, continuing sewing or reversing the rotating shaft of the power piece to the initial needle pitch value;

step S8, judging whether to continue sewing: if yes, go back to step S3; if not, the next step S9 is entered;

and step S9, ending sewing.

2. The method for adjusting the needle pitch of the thread trimming presser foot of the sewing machine as claimed in claim 1, wherein in the step S4, at the beginning of sewing, the rotating shaft of the power member rotates clockwise from the pitch adjusting section into the presser foot lifting section, and the second presser foot lifting section of the presser foot lifting contour surface of the cam drives the presser foot lifting mechanism to perform the presser foot lifting action to slightly lift the seam; then the rotating shaft of the power part rotates reversely to the position corresponding to the initial needle pitch value in the needle pitch adjusting interval, and normal sewing is carried out.

3. The method for adjusting the needle pitch of the thread trimming presser foot of the sewing machine as claimed in claim 1, wherein in the step S5, when the rotating shaft of the power member rotates counterclockwise from the thread trimming interval to the thread trimming interval, before entering the thread trimming interval, the first transition section of the thread trimming contour surface of the cam drives the thread pitch adjusting mechanism to perform the thread pitch adjusting operation so that the needle pitch is transited from the initial needle pitch value to 0, at this time, the thread trimming mechanism and the presser foot lifting mechanism are not operated, and when the needle pitch is transited to 0, the thread encrypting sewing operation is performed and then the thread trimming operation is performed.

4. The method for adjusting the needle pitch of the trimming presser foot of the sewing machine according to claim 1, wherein in the step S7, if the trimming operation and the presser foot lifting operation are not performed before the step S7, the sewing is continued, and the next step S8 is proceeded; if the presser foot raising operation is performed before step S7, the process proceeds directly to the next step S8; if the trimming operation is performed and the presser foot lifting operation is not performed before step S7, the rotating shaft of the power element is rotated clockwise from the trimming section to the position corresponding to the initial pitch value in the pitch adjustment section in step S7, and at this time, the trimming segment of the trimming contour surface of the cam drives the trimming mechanism to be operated in the reverse direction and reset, and the presser foot lifting mechanism is not operated.