A control method for a sewing machine

Abstract

The application provides a sewing machine control method, comprising: acquiring a current thickness value of a sewing material in real time, judging whether the sewing material is in an n-th sewing material thickness interval and an n-th sewing mode to be executed; a rotating motor starts to rotate in a first direction, when a limiting part abuts against a lifting tooth eccentric wheel but has not entered a groove, the rotating motor is blocked and feeds back to a controller, at this time, the controller controls a main shaft motor to drive the main shaft to rotate until the groove is opposite to the limiting part, the blocking signal disappears, the rotating motor can continue to rotate to a preset angle, driving the limiting part to enter the groove, at this time, the rotating motor and the main shaft motor stop working; and the angle value of the main shaft is changed according to parameter setting in the n-th sewing mode. The sewing machine control method provided by the application can adjust the feeding timing by the collaborative control of a feeding motor, a main shaft motor and a rotating motor, and can judge the disengaging and engaging condition between the main shaft and the lifting tooth eccentric wheel according to the blocking signal of the rotating motor, so that the control is more accurate.

Description

TECHNICAL FIELD

[0001] The present application relates to the sewing machine technical field, especially to a control method of a sewing machine. BACKGROUND

[0002] In order to realize the feeding of cloth, the existing sewing machine is provided with a feeding mechanism to drive the feeding needle to make the compound motion of up-down reciprocating and front-back reciprocating. Figure 1 As shown in the figure, the current feeding mechanism mainly includes a main shaft motor 40, a main shaft 41 driven to rotate by the main shaft motor 40, a lifting needle assembly connected between the main shaft 41 and the needle frame 5, a feeding motor 10, and a feeding assembly connected between the feeding motor 10 and the needle frame 5. Among them, the lifting needle assembly includes a lifting needle eccentric wheel 43 fixed on the main shaft 41 through a fastener, a lifting needle connecting rod 46, a lifting needle crank 47, a lifting needle shaft 48, a lifting needle swing fork 49, and a lifting needle sliding block 491 hinged with the needle frame 5 and in sliding cooperation with the lifting needle swing fork 49. The upper end of the lifting needle connecting rod 46 is rotatably installed on the outer periphery of the lifting needle eccentric wheel 43, the lower end of the lifting needle connecting rod 46 is hinged with the lifting needle crank 47, and the lifting needle crank 47 and the lifting needle swing fork 49 are respectively fixed on both ends of the lifting needle shaft 48. When the main shaft motor 40 drives the main shaft 41 to rotate, the main shaft 41 drives the needle frame 5 and the feeding needle 6 fixed on the needle frame 5 to make up-down reciprocating motion along the vertical direction through the lifting needle assembly, which affects the displacement S Y of the feeding needle 6 in the Y-axis direction. The feeding assembly includes a feeding crank 11 fixed on the output shaft of the feeding motor 10, a feeding connecting rod 12, and a needle frame seat 13 rotatably supported in the sewing machine base plate. The two ends of the feeding connecting rod 12 are respectively hinged with the feeding crank 11 and the needle frame seat 13, and the needle frame seat 13 is connected with the needle frame 5. When the output shaft of the feeding motor 10 reciprocates, it drives the needle frame 5 and the feeding needle 6 to make front-back reciprocating motion along the horizontal direction through the feeding assembly, which affects the displacement S X of the feeding needle 6 in the X-axis direction. S X and S Y are functions of the main shaft rotation angle . Figure 2

[0003] The feeding timing refers to the time when the feeding needle pops out of the needle plate and the time when it sinks into the needle plate. As shown in Figure 2 and Figure 3 , t1 is the point when the feeding needle pops out of the needle plate, and t2 is the point when the feeding needle sinks into the needle plate. However, since the lifting needle eccentric wheel is fixed on the main shaft through a fastener, its position angle relative to the main shaft cannot be adjusted, so the main shaft rotation angle corresponding to t1 and t2 is also fixed, resulting in the unadjustable feeding timing. In actual work, only the displacement S X ​Changing the motion trajectory of the feed dog will result in poor adaptability of the sewing machine to different types of sewing materials, and cannot meet the sewing requirements of all fabrics, making it difficult to adapt to the current diversified and personalized production environment.

[0004] Therefore, there is an urgent need for a sewing machine control method. SUMMARY

[0005] To solve the above-mentioned defects, the technical problem to be solved by the present application is to provide a sewing machine control method that can automatically change the motion trajectory of the feed dog according to the thickness of the fabric, improving the adaptability of the sewing machine to different fabrics.

[0006] The present application provides a control method for a sewing machine, which comprises a main shaft motor, a main shaft driven to rotate by the main shaft motor, a dog rack, a feed dog mounted on the dog rack, and a dog lifting assembly for connecting the main shaft and the dog rack, a rotating motor, a dog lifting clutch assembly, and a feed timing adjustment assembly connected between the rotating motor and the dog lifting clutch assembly; the dog lifting eccentric wheel in the dog lifting assembly is connected with the main shaft through the dog lifting clutch assembly, a groove is opened on the outer periphery of the dog lifting eccentric wheel, and the feed timing adjustment assembly comprises a limiting piece facing the dog lifting eccentric wheel; when the sewing machine is working normally, the limiting piece is away from the dog lifting eccentric wheel, the dog lifting clutch assembly allows power transmission between the main shaft and the dog lifting eccentric wheel, and the main shaft can drive the dog lifting eccentric wheel to rotate synchronously; when the feed timing needs to be adjusted, the rotating motor drives the limiting piece to approach the dog lifting eccentric wheel and enter the groove, the dog lifting clutch assembly blocks the power transmission between the main shaft and the dog lifting eccentric wheel, the main shaft and the dog lifting eccentric wheel rotate relatively, the positioning angle between the main shaft and the dog lifting eccentric wheel is changed, and the feed timing is changed; the control method comprises the following steps:

[0007] S1, preset N fabric thickness intervals, N sewing modes and N positioning angle values between the main shaft and the dog lifting eccentric wheel in the controller of the sewing machine, N is a natural number greater than 1; the nth fabric thickness interval, the nth sewing mode and the nth positioning angle value correspond to each other, n is a natural number less than or equal to N;

[0008] S2, real-time acquisition of the current thickness value of the fabric at the needle, judgment of whether it is in the nth fabric thickness interval and the nth sewing mode to be executed according to the current thickness value; at the same time, the positioning angle value between the current main shaft and the dog lifting eccentric wheel is acquired, if the current positioning angle value is the same as the nth positioning angle value, the sewing machine works normally; if they are different, step S3 is entered;

[0009] S3, the rotary motor drives the limiting member to approach the lifting tooth eccentric wheel, when the limiting member abuts against the lifting tooth eccentric wheel but has not entered the groove, the rotary motor stalls and feeds back to the controller, the controller controls the main shaft motor to drive the main shaft to rotate until the groove is opposite to the limiting member, the stall signal disappears, and the rotary motor drives the limiting member to enter the groove;

[0010] S4, the main shaft motor drives the main shaft to rotate until the positioning angle value between the current main shaft and the lifting tooth eccentric wheel is the same as the nth positioning angle value.

[0011] Preferably, the sewing machine further comprises a feed motor and a feed assembly for connecting the feed motor and the needle frame; the control method further comprises the step of adjusting the output rule of the feed motor according to the parameters in the nth sewing mode, so that the phase difference between the X-direction motion track and the Y-direction motion track of the feed needle remains unchanged.

[0012] Preferably, the method further comprises the step S5 of adjusting the stitch value of the sewing machine so that the stitch values before and after the feed timing adjustment remain unchanged.

[0013] Preferably, the sewing machine further comprises a feed assembly connected between the main shaft and the needle frame, the feed assembly comprising a feed swing seat rotating around a feed support shaft, the position of the feed support shaft being fixed, the feed swing seat being connected to the output shaft of the rotary motor through a stitch adjustment assembly, and the angle of the feed swing seat determining the stitch value of the sewing machine; in the step S5, the rotation angle of the output shaft of the rotary motor is adjusted to change the angle of the feed swing seat, thereby adjusting the stitch value of the sewing machine.

[0014] Preferably, the sewing machine further comprises a feed motor and a feed assembly for connecting the feed motor and the needle frame; in the step S5, the output rule of the feed motor is adjusted to change the X-direction motion track of the feed needle, thereby adjusting the stitch value of the sewing machine.

[0015] Preferably, after the step S3 and before the step S4, the method further comprises the step S31 of stopping the rotary motor and the main shaft motor, reading the current angle value of the main shaft, and setting the current angle value as the adjustment starting angle value.

[0016] Preferably, the lifting tooth clutch assembly comprises a ratchet fixed on the main shaft, a sliding groove opened on the end face of the lifting tooth eccentric wheel, and a sliding piece in sliding cooperation with the sliding groove, the sliding piece being provided with a clamping tooth part; when the sewing machine is normally working, the clamping tooth part is engaged with the ratchet; when the feed timing is adjusted, the clamping tooth part is separated from the ratchet.

[0017] Preferably, the fabric feeding timing adjustment assembly comprises a fabric feeding timing adjustment lever hinged to the sewing machine housing, and a fabric feeding timing adjustment cam arranged on the output shaft of the rotary motor, one end of the fabric feeding timing adjustment lever being hinged with a fabric feeding timing adjustment roller, the fabric feeding timing adjustment roller abutting against the fabric feeding timing adjustment cam; the other end of the fabric feeding timing adjustment lever being connected with the limiting piece.

[0018] Preferably, the sewing machine further comprises a presser foot lifting assembly connected with the output shaft of the rotary motor and the presser foot respectively; the step S2 further comprises: judging whether the presser foot needs to be lifted according to the current thickness value of the sewing material; when the presser foot height needs to be adjusted, the output shaft of the rotary motor rotates to drive the presser foot lifting assembly to lift the presser foot.

[0019] The sewing machine control method provided by the application can adjust the fabric feeding timing through the cooperative control of the main shaft motor and the rotary motor, and can control more accurately according to the rotary motor stall signal to judge the clutching condition between the main shaft and the lifting tooth eccentric wheel; after adjusting the fabric feeding timing, the stitch value can be adjusted by cooperating with the electronic control and different fabric feeding assemblies of the sewing machine, so as to ensure the stability of the stitch value before and after adjusting the fabric feeding timing, the adjustment mode is simple and practical, the cost is low, the electronic control adjustment requirement can be completely met under the electronic fabric feeding and the common stepping platform of the lockstitch machine, and the universality is strong; in addition, the automatic presser foot lifting function can be realized through the same rotary motor, so that the function of the sewing machine is more comprehensive and perfect. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 Fig. 1 is a structural schematic diagram of the existing fabric feeding mechanism;

[0021] Figure 2 Fig. 2 is a function curve diagram of the X direction and Y direction movement displacement of the fabric feeding tooth and the rotation angle of the main shaft of the sewing machine in the prior art;

[0022] Figure 3 Fig. 3 is a fabric feeding tooth trajectory diagram in the prior art;

[0023] Figure 4 Fig. 4 is a schematic diagram of the internal structure of the sewing machine of embodiment one;

[0024] Figure 5 Fig. 5 is a schematic diagram of the rotation angle of the output shaft of the rotary motor of embodiment one;

[0025] Figure 6 Fig. 6 is a structural schematic diagram of the fabric feeding timing adjustment assembly of embodiment one;

[0026] Figure 7 Fig. 7 is a structural schematic diagram of the lifting tooth clutching assembly of embodiment one;

[0027] Figure 8The cooperation diagram of the thread feeding timing adjusting assembly and the presser foot lifting clutch assembly of example one;

[0028] Figure 9 The structure diagram of the presser foot lifting assembly of example one;

[0029] Figure 10 The four movement track diagrams of the thread feeding dog;

[0030] Figure 11 The internal structure diagram of the sewing machine of example two;

[0031] Figure 12 The Figure 11 The enlarged view of A in the middle;

[0032] Figure 13 The rotation angle diagram of the output shaft of the rotary motor of example two;

[0033] Figure 14 The structure diagram of the stitch length adjusting assembly of example two;

[0034] Figure 15 The function curve diagram of the X direction displacement, Y direction displacement and the main shaft rotation angle of the thread feeding dog of the present application;

[0035] Figure 16 The relationship diagram of the thread take-up lever and the thread feeding timing.

[0036] Element number explanation:

[0037] 10 Thread feeding motor

[0038] 11 Thread feeding crank

[0039] 12 Thread feeding connecting rod

[0040] 13 Dog frame seat

[0041] 14 Feeding shaft

[0042] 15 Feeding swing seat

[0043] 151 Left arm part

[0044] 152 Right arm part

[0045] 16 Feeding connecting rod

[0046] 17 Feeding eccentric wheel

[0047] 18 Feeding crank

[0048] 191 First feeding swing plate

[0049] 192 Second feeding swing plate

[0050] 100 feeding support shaft

[0051] 21 presser foot cam

[0052] 211 first driving part

[0053] 212 first avoiding part

[0054] 22 presser foot roller

[0055] 23 presser lever

[0056] 24 bracket

[0057] 25 top rod

[0058] 26 rear lever

[0059] 27 pull rod

[0060] 28 front lever

[0061] 29 presser foot

[0062] 31 feed timing adjusting cam

[0063] 311 second driving part

[0064] 312 second avoiding part

[0065] 32 first support pin

[0066] 33 limiting piece

[0067] 34 torsion spring

[0068] 35 feed timing adjusting lever

[0069] 36 feed timing adjusting roller

[0070] 40 main shaft motor

[0071] 41 main shaft

[0072] 42 ratchet wheel

[0073] 43 toothed cam

[0074] 431 sliding groove

[0075] 432 recess

[0076] 44 stop ring

[0077] 45 sliding sheet

[0078] 451 toothed part

[0079] 46 toothed lever

[0080] 47 toothed rear lever

[0081] 48 Tooth-lifting shaft

[0082] 49. Lifting Tooth Swing Fork

[0083] 491 Tooth Lifting Slider

[0084] 5 dental frame

[0085] 6. Feeding teeth

[0086] 70 Rotary Motor

[0087] 701 Output Shaft

[0088] 81 Pitch Adjustment Cam

[0089] 811 Third Drive Unit

[0090] 812 Third Avoidance Section

[0091] 82 Pitch Adjusting Roller

[0092] 83 Pitch Adjustment Crank

[0093] 831 Second Support Pin

[0094] 84 Pitch Adjustment Link

[0095] 85 Return Spring

[0096] 9. Needle-punching mechanism Detailed Implementation

[0097] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. These embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0098] In the description of this invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0099] In the following description, Figure 4The drawings in the figures are used as a reference basis for the orientation, the downward direction along the plane of the drawing, and the upward direction along the plane of the drawing; the axial direction of the main shaft 41 is the left-right direction, wherein the direction of the main shaft 41 toward the sewing machine head (i.e., the needle side) is the left direction, and the direction of the main shaft 41 toward the sewing machine tail is the right direction; the direction perpendicular to the aforementioned upward-downward direction and left-right direction is the front-rear direction, wherein the direction of the tooth holder seat 13 is the front direction, and the direction of the tooth lifting swing fork 49 is the rear direction. The front-rear direction is defined as the X-axis direction, and the upward-downward direction is defined as the Y-axis direction.

[0100] The sewing machine used in the present application, as shown in Figure 4 , comprises a main shaft motor 40, a main shaft 41 driven to rotate by the main shaft motor 40, a tooth holder 5, a feed dog 6 fixedly installed on the tooth holder 5, a tooth lifting assembly for connecting the main shaft 41 and the tooth holder 5, a rotary motor 70, a tooth lifting clutch assembly, and a feed timing adjustment assembly connected between the rotary motor 70 and the tooth lifting clutch assembly.

[0101] The tooth lifting assembly, as shown in Figure 4 and Figure 7 , comprises a tooth lifting eccentric wheel 43 sleeved on the outer periphery of the main shaft 41 and having a tooth lifting eccentric portion, a tooth lifting connecting rod 46, a tooth lifting crank 47, and a tooth lifting shaft 48 parallel to the main shaft 41, the tooth lifting eccentric portion is located at the left end of the tooth lifting eccentric wheel 43, the upper end of the tooth lifting connecting rod 46 is rotatably installed on the outer periphery of the tooth lifting eccentric portion, the lower end is hingedly connected with the tooth lifting crank 47, the right end of the tooth lifting shaft 48 is fixedly connected with the tooth lifting crank 47, and the left end is connected with the rear end of the tooth holder 5 through the tooth lifting swing fork 49 and the tooth lifting sliding block 491.

[0102] The tooth lifting eccentric wheel 43 is connected with the main shaft 41 through the tooth lifting clutch assembly. When the feed timing is not adjusted, the tooth lifting clutch assembly allows power transmission between the main shaft 41 and the tooth lifting eccentric wheel 43, the main shaft 41 drives the tooth lifting eccentric wheel 43 to rotate synchronously, the tooth lifting eccentric wheel 43 drives the tooth lifting shaft 48 to reciprocate through the tooth lifting connecting rod 46 and the tooth lifting crank 47, and then drives the tooth holder 5 and the feed dog 6 to move up and down, so that the feed dog 6 generates displacement S Y in the Y-axis direction.

[0103] The rotary motor 70 is fixedly installed in the sewing machine housing, and preferably uses a low-noise stepping motor, which is connected with the controller of the sewing machine.

[0104] To realize the function of adjusting the feed timing, as shown in Figure 7 and Figure 8 , the rotary motor 70 is connected with the tooth lifting clutch assembly through the feed timing adjustment assembly, and the tooth lifting clutch assembly is connected with the tooth holder 5 through the tooth lifting shaft 48.As shown, the lifting tooth clutch assembly includes a ratchet wheel 42 fixed on the main shaft 41 by a screw, a sliding groove 431 opened on the right end surface of the lifting tooth eccentric wheel 43, a sliding sheet 45 in sliding cooperation with the sliding groove 431, and a stop ring 44 fixed on the main shaft 41 by a screw. Among them, the sliding sheet 45 is provided with a clamping tooth part 451, the ratchet wheel 42 is located on the right side of the lifting tooth eccentric wheel 43, and the stop ring 44 is located on the left side of the lifting tooth eccentric wheel 43, which axially limits the lifting tooth eccentric wheel 43. The lifting tooth clutch assembly further comprises a reset torsion spring (not shown) fixedly installed on the right end surface of the lifting tooth eccentric wheel 43, one end of the reset torsion spring acts on the clamping tooth part 451, and an acting force along the extension direction of the sliding groove 431 towards the ratchet wheel 42 is applied to the clamping tooth part 451, so that the clamping tooth part 451 and the ratchet wheel 42 remain in the engaged state without external force.

[0105] As shown, Figures 4-8 The fabric feeding timing adjusting assembly includes a first support pin 32 fixed on the sewing machine shell by a screw, a torsion spring 34 sleeved on the first support pin 32, and a fabric feeding timing adjusting lever 35 hinged on one end of the first support pin 32. The lower end of the fabric feeding timing adjusting lever 35 is hinged with a fabric feeding timing adjusting roller 36, and the upper end is provided with a limiting piece 33 towards the lifting tooth eccentric wheel 43. The outer periphery of the lifting tooth eccentric wheel 43 is provided with a groove 432 for the limiting piece 33 to enter, and the groove 432 is in communication with the sliding groove 431. The fabric feeding timing adjusting assembly further comprises a fabric feeding timing adjusting cam 31 arranged on the output shaft 701 of the rotary motor 70, which abuts against the fabric feeding timing adjusting roller 36. One end of the torsion spring 34 acts on the fabric feeding timing adjusting lever 35, and the other end is fixed, which applies an acting force to make the fabric feeding timing adjusting roller 36 tightly abut against the fabric feeding timing adjusting cam 31, and make the limiting piece 33 away from the lifting tooth eccentric wheel 43.

[0106] When the sewing machine works normally, the main shaft motor 40 drives the main shaft 41 to rotate, and the clamping tooth part 451 is engaged with the ratchet wheel 42, at this time the main shaft 41 drives the lifting tooth eccentric wheel 43 to rotate synchronously through the ratchet wheel 42, the clamping tooth part 451 and the sliding sheet 45. The initial relative positioning angle of the lifting tooth eccentric wheel 43 and the main shaft 41 is determined by the initial engagement position of the ratchet wheel 42 and the clamping tooth part 451. The main shaft 41 drives the tooth frame 5 and the fabric feeding tooth 6 fixed on the tooth frame 5 to move up and down along the vertical direction through the lifting tooth assembly, forming the displacement S of the fabric feeding tooth 6 in the Y axis direction Y .

[0107] When the timing of the fabric feeding is adjusted, the output shaft 701 of the rotating motor 70 rotates, the timing of the fabric feeding adjusting roller 36 swings forward under the action of the pushing force provided by the timing of the fabric feeding adjusting cam 31, the upper end of the timing of the fabric feeding adjusting lever 35 and the limiting piece 33 are driven to approach the lifting tooth eccentric wheel 43 against the action of the torsion spring 34, the limiting piece 33 pushes the sliding sheet 45 in the process of entering the groove 432, the sliding sheet 45 is partially pushed away from the sliding groove 431 under the action, the clamping tooth part 451 is separated from the ratchet wheel 42, and in this process, the clamping tooth part 451 needs to overcome the action of the reset torsion spring. At this time, the main shaft 41 rotates, that is, the positioning angle between the main shaft 41 and the lifting tooth eccentric wheel 43 can be changed, the time t1 when the fabric feeding tooth 6 emerges from the needle plate and the time t2 when the fabric feeding tooth 6 sinks into the needle plate are changed, and the Y-direction movement track of the fabric feeding tooth 6 is changed while the timing of the fabric feeding is adjusted.

[0108] The sewing machine control method provided by the application comprises the following steps:

[0109] S1, presetting N fabric thickness intervals, N sewing modes and positioning angle values between the main shaft and the lifting tooth eccentric wheel in the controller of the sewing machine, N is a natural number greater than 1; the nth fabric thickness interval, the nth sewing mode and the nth positioning angle value correspond to each other, n is a natural number less than or equal to N; here, “correspond to each other” means that the nth fabric thickness interval corresponds to the nth sewing mode and the nth positioning angle value, and the nth sewing mode corresponds to the nth positioning angle value.

[0110] S2, acquiring the current thickness value of the fabric at the needle in real time, judging whether the current thickness value is in the nth fabric thickness interval and the nth sewing mode should be executed according to the current thickness value; at the same time, acquiring the positioning angle value between the current main shaft 41 and the lifting tooth eccentric wheel 43, if the current positioning angle value is the same as the nth positioning angle value, the sewing machine works normally; if not, step S3 is entered;

[0111] S3, the main shaft motor 40 drives the main shaft 41 to rotate to a specified position first, then the output shaft 701 of the rotating motor 70 rotates to the first direction, the limiting piece 33 is driven to approach the lifting tooth eccentric wheel 43 through the timing of the fabric feeding adjusting assembly, when the limiting piece 33 abuts against the outer periphery of the lifting tooth eccentric wheel 43 but has not entered the groove 432, the rotating motor 70 stalls and feeds back to the controller, the controller controls the main shaft motor 40 to drive the main shaft 41 to rotate, the main shaft 41 drives the lifting tooth eccentric wheel 43 to rotate synchronously, until the groove 432 is opposite to the limiting piece 33, the stall signal disappears, and the rotating motor 70 drives the limiting piece 33 to enter the groove 432.

[0112] S4, the main shaft motor 40 drives the main shaft 41 to rotate, until the positioning angle value between the current main shaft 41 and the lifting tooth eccentric wheel 43 is the same as the nth positioning angle value, the adjustment of the timing of the fabric feeding is completed.

[0113] The sewing machine control method provided by the present application can adjust the cloth feeding timing through the cooperative control of the main shaft motor 40 and the rotating motor 70, and determine the disengagement between the pawl part 451 and the ratchet wheel 42 according to the stall signal of the rotating motor 70, and further determine the disengagement between the main shaft 41 and the lifting tooth eccentric wheel 43, so that the control is more accurate. Further, in step S3, the main shaft motor 40 first drives the main shaft 41 to rotate to a specified position, and then controls the rotating motor 70 to work, which can optimize the control process, reduce the adjustment time, and improve the control accuracy.

[0114] To improve the adjustment accuracy, after the above step S3 and before step S4, there is also a step S31: the rotating motor and the main shaft motor stop working, the current angle value of the main shaft 41 is read, and the current angle value is set as the adjustment starting angle value.

[0115] The movement track of the limiting part 33 is a fixed movement track due to the mechanical structure limitation, and it will enter the groove 432 at a fixed position, so when the limiting part 33 enters the groove 432, the rotation angle of the lifting tooth eccentric wheel 43 is a fixed value, so in step S4, only the rotation angle of the main shaft 41 needs to be adjusted to change the positioning angle value between the main shaft 41 and the lifting tooth eccentric wheel 43. After the adjustment starting angle value is determined, when the positioning angle value between the main shaft 41 and the lifting tooth eccentric wheel 43 needs to be adjusted according to different sewing modes, the main shaft 41 can be controlled to rotate by a corresponding angle with the adjustment starting angle value as the starting point, so as to avoid the cumulative adjustment error caused by repeatedly determining the starting point of the main shaft 41 rotation, and prevent the accuracy of subsequent adjustment from being reduced.

[0116] As shown in Figure 9 Further, the sewing machine of the present application also comprises a presser foot lifting assembly, which comprises a bracket 25 fixedly installed inside the sewing machine housing through screws, a presser foot lever 24 hinged on the bracket 25 through a pin shaft, a presser foot lifting roller 22 hinged on the rear end of the presser foot lever 24, and a top rod 25, a rear lever 26, a pull rod 27, and a front lever 28 successively hinged on the front end of the presser foot lever 24, forming a linkage structure, the front lever 28 being connected with a presser foot 29, and the rear lever 26 being hinged with the sewing machine housing. The presser foot lifting roller 22 abuts against a presser foot lifting cam 21 arranged on the output shaft 701 of the rotating motor 70. When the rotating motor 70 drives the presser foot lifting cam 21 to rotate, the presser foot lifting roller 22 is swung forward under the action of the thrust force provided by the presser foot lifting cam 21, and drives the presser foot 29 to gradually lift through the linkage structure until reaching the required height.

[0117] The above step S2 also comprises: determining whether the presser foot needs to be lifted according to the current thickness value of the sewing material, and when the height of the presser foot 29 needs to be adjusted, the output shaft 701 of the rotating motor 70 rotates to drive the presser foot lifting assembly to lift the presser foot 29.

[0118] As Figure 5 shown, the aforementioned presser lifting cam 21 and the timing cam 31 for fabric feeding are two separate parts, which are arranged on the output shaft 701 at intervals. The presser lifting cam 21 comprises a first driving part 211 formed by a variable diameter surface and a first avoiding part 212 formed by a constant diameter surface, and the timing cam 31 for fabric feeding comprises a second driving part 311 formed by a variable diameter surface and a second avoiding part 312 formed by a constant diameter surface.

[0119] During the rotation of the output shaft 701 of the rotary motor 70 by 0°-360° (i.e. one rotation), the rotation angle has the presser lifting area W1 and the timing area W2 for fabric feeding which are independent of each other.

[0120] When the output shaft 701 of the rotary motor 70 operates in the presser lifting area W1, the first driving part 211 of the presser lifting cam 21 is in contact with the presser lifting roller 22, the rotary motor 70 drives the presser 29 to be lifted through the presser lifting assembly, and the automatic presser lifting function is realized; when the output shaft 701 operates outside the presser lifting area W1, the first avoiding part 212 of the presser lifting cam 21 is in contact with the presser lifting roller 22, so that the rotary motor 70 and the presser lifting assembly are not in power transmission, and the lifting height of the presser 29 is unchanged.

[0121] When the output shaft 701 operates in the timing area W2 for fabric feeding, the second driving part 311 of the timing cam 31 for fabric feeding is in contact with the timing roller 36 for fabric feeding, the rotary motor 70 drives the lifting tooth clutch assembly to block the power transmission between the main shaft 41 and the lifting tooth eccentric wheel 43 through the timing assembly for fabric feeding, and the timing function for fabric feeding is realized; when the output shaft 701 operates outside the timing area W2 for fabric feeding, the second avoiding part 312 of the timing cam 31 for fabric feeding is in contact with the timing roller 36 for fabric feeding, so that the rotary motor 70 and the lifting tooth clutch assembly are not in power transmission, and the main shaft 41 drives the lifting tooth eccentric wheel 43 to rotate synchronously.

[0122] The relative angle between the driving parts of the two cams on the output shaft 701 can be adjusted by the person skilled in the art as needed to meet the functional switching requirements. In addition, the presser lifting cam 21 and the timing cam 31 for fabric feeding can also be an integral part, which comprises a cylindrical body sleeved on the output shaft 701 and the first driving part 211 and the second driving part 311 arranged on the cylindrical body in a staggered manner, and the outer wall of the cylindrical body serves as the first avoiding part 212 / second avoiding part 312, which can also meet the functional requirements.

[0123] As Figure 15 and Figure 16 shown, the working principle of the present application is:

[0124] When the positioning angle between the main shaft 41 and the presser foot eccentric wheel 43 becomes smaller after adjusting the timing of the fabric feeding, the fabric feeding action is advanced, and the X-direction movement track and the Y-direction movement track of the fabric feeding needle are both shifted to the left. In this state, part of the thread is already clamped by the fabric and the needle plate when the thread tensioner starts to take up the thread, so the resistance of the thread tensioner to take up the thread becomes larger, which makes the thread not easy to be tightened, the fabric is not easy to be wrinkled when sewing thin fabric, and the sewing requirement of the thin fabric is met.

[0125] When the positioning angle between the main shaft 41 and the presser foot eccentric wheel 43 becomes larger, the fabric feeding action is delayed, and the X-direction movement track and the Y-direction movement track of the fabric feeding needle are both shifted to the right. In this state, the thread is clamped by the fabric and the needle plate when the thread tensioner starts to take up the thread, so the resistance of the thread tensioner to take up the thread becomes smaller, the thread is easier to be tightened when sewing thick fabric, and the sewing requirement of the thick fabric is met.

[0126] As shown in Figure 4 the present application adjusts the timing of the fabric feeding by adjusting the positioning angle between the presser foot eccentric wheel 43 and the main shaft 41, which improves the sewing adaptability of the sewing machine to different fabrics. However, when the main shaft 41 rotates, the timing of the fabric penetrating mechanism 9 directly driven by the main shaft 41 will also change, which makes the time when the needle penetrates into the fabric advance or delay relative to the timing of the fabric feeding, and finally causes the size of the stitch on the fabric to change, which leads to the inconsistency of the stitch size before and after adjusting the timing of the fabric feeding, and cannot meet the requirement of accurate and stable stitch. Therefore, the control method of the present application further includes step S5: adjusting the stitch size of the sewing machine, so that the stitch size before and after adjusting the timing of the fabric feeding remains consistent.

[0127] For how to implement step S5, the present application provides the following two embodiments, which will be specifically described below in combination with the embodiments.

[0128] Embodiment One

[0129] The sewing machine used in embodiment one is shown in Figure 4 , which includes a fabric feeding motor 10 and a fabric feeding assembly for connecting the fabric feeding motor 10 and the needle frame 5. Specifically, the fabric feeding assembly includes a fabric feeding crank 11, a fabric feeding connecting rod 12, and a needle frame seat 13 rotatably supported in the sewing machine base plate, the fabric feeding crank 11 is fixed on the output shaft of the fabric feeding motor 10, the two ends of the fabric feeding connecting rod 12 are respectively hinged to the fabric feeding crank 11 and the needle frame seat 13, and the needle frame seat 13 is connected to the front end of the needle frame 5.

[0130] When the output shaft of the fabric feeding motor 10 reciprocates, it drives the needle frame 5 and the fabric feeding needle 6 to move back and forth along the horizontal direction through the fabric feeding assembly, which affects the displacement S XTherefore, in step S5, the amplitude of the forward and backward swing of the feed dog crank 11 can be adjusted by changing the output law of the feed motor 10, the X-direction movement track of the feed dog can be changed, and the stitch length can be changed, so that the stitch length before and after the adjustment of the feed timing can be kept consistent. For example, after the adjustment of the feed timing, the actual stitch length on the fabric becomes smaller, and the controller adjusts the output law of the feed motor 10 according to the parameter setting, so that the amplitude of the forward and backward swing of the feed dog 6 is increased to compensate for the lost stitch length, so that the stitch length before and after the adjustment is kept consistent. Conversely, the same applies.

[0131] In embodiment one, by changing the output law of the feed motor 10 and matching the Y-direction movement track of the feed dog 6, four kinds of movement tracks of the feed dog can be obtained as shown in Figure 10 Figure 10 (a) is a positive elliptical track suitable for sewing ordinary thick materials, Figure 10 (b) is a nearly vertical elliptical track suitable for sewing thin materials, Figure 10 (c) is a far vertical elliptical track suitable for sewing thick materials, and Figure 10 (d) is a rectangular elliptical track suitable for sewing thick materials.

[0132] In addition to adjusting the stitch length, during the adjustment of the feed timing, if the Y-direction movement track of the feed dog 6 is to be advanced or delayed by a certain phase, the output law of the feed motor 10 also needs to be adjusted so that the X-direction movement track of the feed dog 6 is also advanced or delayed by a certain phase, so that the phase difference between the X-direction movement track and the Y-direction movement track of the feed dog remains unchanged. The specific meaning of the "phase difference" here is that during the rotation of the main shaft 41 by 360°, the angle difference between the main shaft angle corresponding to the minimum X-direction displacement in the X-direction movement track of the feed dog and the main shaft angle corresponding to the minimum Y-direction displacement in the Y-direction movement track of the feed dog.

[0133] Therefore, the control method of embodiment one further comprises the step of adjusting the output law of the feed motor 10 according to the parameter setting in the nth sewing mode, so that the phase difference between the X-direction movement track and the Y-direction movement track of the feed dog 6 remains unchanged. This step can be arranged after step S2 and before step S3, or arranged after step S4 and before step S5.

[0134] As shown in Figure 5 In embodiment one, the range of the presser foot lifting area W1 is 0°-a1, and the range of the feed timing adjustment area W2 is a2-360°, where 0° ​

[0135] The control method of the embodiment one comprises the following steps:

[0136] S1, presetting N fabric thickness intervals, N sewing modes and the positioning angle values between the N spindles and the presser foot eccentric wheels in the controller of the sewing machine, N is a natural number greater than 1; the nth fabric thickness interval, the nth sewing mode and the nth positioning angle value correspond to each other, n is a natural number less than or equal to N.

[0137] S2, judging whether the presser foot needs to be lifted according to the current thickness value of the fabric, when the height of the presser foot 29 needs to be adjusted, the output shaft 701 of the rotary motor 70 rotates from the original point to a certain angle value in the presser foot lifting area W1, the first driving part 211 of the presser foot lifting cam 21 is in contact with the presser foot roller 22, and the rotary motor 70 drives the presser foot 29 to lift through the presser foot lifting assembly. Then, the current thickness value of the fabric at the needle is obtained in real time according to the fabric thickness detection sensor signal arranged at the needle plate, and it is judged that the current thickness value is in the nth fabric thickness interval and the nth sewing mode should be executed; at the same time, the positioning angle value between the current spindle 41 and the presser foot eccentric wheel 43 is obtained, if the current positioning angle value is the same as the nth positioning angle value, the sewing machine works normally; if not, step S3 is entered.

[0138] S3, the spindle motor 40 first drives the spindle 41 to rotate to the specified position, and then the output shaft of the rotary motor 70 rotates from the current angle value to the fabric feeding timing adjustment area W2, at this time the second driving part 311 of the fabric feeding timing adjustment cam 31 is in contact with the fabric feeding timing adjustment roller 36, and the rotary motor 70 drives the limiting part 33 to approach the presser foot eccentric wheel 43 through the fabric feeding timing adjustment assembly, when the limiting part 33 abuts against the outer periphery of the presser foot eccentric wheel 43 but has not yet entered the groove 432, the rotary motor 70 occurs to be blocked and feeds back to the controller, the controller controls the spindle motor 40 to drive the spindle 41 to rotate at a speed less than or equal to 200 r / min, the spindle 41 drives the presser foot eccentric wheel 43 to rotate synchronously, until the groove 432 is opposite to the limiting part 33, the rotary motor 70 is blocked, the blocking signal disappears, the rotary motor 70 drives the limiting part 33 to enter the groove 432, and the presser foot eccentric wheel 43 is separated from the spindle 41.

[0139] S31, the rotary motor 70 and the spindle motor 40 stop working, and the current angle value of the spindle 41 is read and set as the adjustment starting angle value.

[0140] S4, the spindle motor 40 drives the spindle 41 to rotate an angle value x with the adjustment starting angle value as the starting point, so that the positioning angle value between the current spindle 41 and the presser foot eccentric wheel 43 is the same as the nth positioning angle value, and the fabric feeding timing is adjusted.

[0141] S51, adjust the output rule of the feed motor 10 according to the parameter setting in the nth sewing mode, so that the phase difference between the X-direction movement track and the Y-direction movement track of the feed dog 6 remains unchanged.

[0142] If the movement track of the feed dog 6 in the nth sewing mode is a positive elliptical track as shown in (a), the output shaft rotation angle of the feed motor 10 is a sine function of the main shaft rotation angle, and the output shaft rotation angle of the feed motor 10 corresponds to the main shaft rotation angle one by one: Figure 10

[0143]

[0144] wherein, is the output shaft rotation angle of the feed motor 10 for keeping the phase difference unchanged; A is the amplitude; ω is the frequency, generally taking a fixed value of 1; is the main shaft rotation angle; is the initial phase; x is the angle change value of the main shaft in step S4, -30°≤x≤30°; a is a constant.

[0145] If the movement track of the feed dog 6 in the nth sewing mode is other than a positive elliptical track, is not a sine function of , which needs to satisfy the Fourier transform rule, and can be defined by the person skilled in the art as needed.

[0146] S5, change the output rule of the feed motor 10 to adjust the forward and backward swing amplitude of the feed crank 11, change the X-direction movement track of the feed dog, and further change the stitch size, so that the stitch values before and after the adjustment of the feed timing remain consistent.

[0147] The output shaft rotation angle of the feed motor 10 can be defined as:

[0148]

[0149] wherein, is the output shaft rotation angle of the feed motor 10 for keeping the stitch value unchanged; f(x) is a stitch compensation function about the angle change value x of the main shaft, which is obtained by calculation or self-definition; b is a constant.

[0150] S6, rotate the output shaft 701 of the motor 70 back to the original position, the panel displays the identification of the nth sewing mode, and the sewing machine starts working;

[0151] S7, when the fabric thickness detection sensor detects the change of the current thickness value of the sewing material at the needle, the above steps S2, S3, S4, S51, S5, S6 are repeated in turn.

[0152] Embodiment Two

[0153] ​The difference between the sewing machine used in the second embodiment and the sewing machine used in the first embodiment is that the sewing machine used in the second embodiment does not include the feed motor 10, the feed assembly of which is connected between the main shaft 41 and the needle bar 5; the rotation angle of the output shaft 701 of the rotation motor 70 further has a stitch length adjusting area W3 in addition to the presser foot lifting area W1 and the feed timing adjusting area W2. The sewing machine used in the second embodiment can realize the three functions of automatic presser foot lifting, automatic feed timing adjustment and automatic stitch length adjustment by means of a rotation motor and an electric control.

[0154] As shown in Figure 11 and Figure 12 , the feed assembly of the sewing machine used in the second embodiment includes a feed eccentric wheel 17 fixed on the main shaft 41, a feed connecting rod 16, a feed support shaft 100 fixed in position and parallel to the main shaft 41, a feed swing base 15 swinging around the feed support shaft 100, a first feed swing plate 191, a second feed swing plate 192, a feed shaft 14 parallel to the main shaft 41, a feed crank 18 fixed on the right end of the feed shaft 14 and a needle bar seat 13 rotatably supported in the base plate of the sewing machine. Among them, the upper end of the feed connecting rod 16 is rotatably mounted on the outer periphery of the feed eccentric wheel 17, the lower end of the feed shaft 14, the first end of the first feed swing plate 191 and the first end of the second feed swing plate 192 are coaxially hinged by a pin, the second end of the first feed swing plate 191 is hinged to the feed swing base 15 by a pin, the second end of the second feed swing plate 192 is hinged to the feed crank 18 by a pin, the left end of the feed shaft 14 is fixedly connected to the needle bar seat 13, and the needle bar seat 13 is connected to the front end of the needle bar 5.

[0155] The feed swing base 15 has a concave structure with a left arm portion 151 and a right arm portion 152 arranged opposite to each other and parallel to each other, and the left arm portion 151 and the right arm portion 152 are rotatably connected to the feed support shaft 100, which is arranged in the housing of the sewing machine; the number of the first feed swing plate 191 and the second feed swing plate 192 is two, and the two second feed swing plates 192 are arranged on the left and right sides of the lower end of the feed connecting rod 16, one first feed swing plate 191 is located between the left arm portion 151 and the left second feed swing plate 192, and the other first feed swing plate 191 is located between the right arm portion 152 and the right second feed swing plate 192.

[0156] The sewing machine used in the second embodiment further includes a stitch length adjusting assembly connected between the output shaft 701 and the feed swing base 15. As shown in Figure 13 and Figure 14As shown, the stitch length adjusting assembly comprises a stitch length adjusting cam 81 arranged on the output shaft 701, a second support pin 831 arranged on the housing of the rotary motor 70, and a stitch length adjusting crank 83, the middle part of which is hingedly connected to one end of the second support pin 831, the rear end of which is hingedly connected to a stitch length adjusting roller 82, and the front end of which is hingedly connected to the feed swing base 15 through a stitch length adjusting connecting rod 84. One end of a return spring 85 is also connected to the stitch length adjusting connecting rod 84, and the other end of the return spring 85 is fixed inside the sewing machine housing. The return spring 85 provides a force to make the stitch length adjusting roller 82 tightly contact the stitch length adjusting cam 81. The stitch length adjusting cam 81 comprises a third driving part 811 formed by a variable diameter surface and a third avoiding part 812 formed by an equal diameter surface.

[0157] As shown, during the rotation of the output shaft 701 by 0°-360° (i.e. one rotation), the range of the presser foot lifting area W1 is 0°-a1, the range of the feed timing adjusting area W2 is a1-a2, the range of the stitch length adjusting area W3 is a3-360°, wherein 0°<a1<a2<a3<360°. Figure 13

[0158] When the output shaft 701 operates in the stitch length adjusting area W3, the third driving part 811 contacts and cooperates with the stitch length adjusting roller 82. The stitch length adjusting roller 82 swings forward under the action of the thrust force, drives the feed swing base 15 to rotate around the feed support shaft 100, changes the angle of the feed swing base 15, changes the transmission efficiency of the feed assembly and the X-direction movement track of the feed dog, and further changes the stitch length of the sewing machine.

[0159] When the output shaft 701 operates outside the stitch length adjusting area W3, the third avoiding part 812 contacts and cooperates with the stitch length adjusting roller 82, so that there is no power transmission between the rotary motor 70 and the feed swing base 15.

[0160] Further, the presser foot lifting cam 21, the feed timing adjusting cam 31, and the stitch length adjusting cam 81 in the second embodiment are three separate parts arranged at intervals on the output shaft 701. Those skilled in the art can adjust the relative angles between the driving parts of the three cams according to the needs to meet the functional switching needs. In addition, the presser foot lifting cam 21, the feed timing adjusting cam 31, and the stitch length adjusting cam 81 can also be an integral part, which comprises a cylindrical body arranged on the output shaft 701 and first, second, and third driving parts arranged on the cylindrical body in a staggered manner. The cylindrical body serves as the first avoiding part / second avoiding part / third avoiding part, which can also meet the functional needs.

[0161] ​As can be seen from the above, in step S5 of the control method of the sewing machine of Embodiment Two, the angle of the feeding swing base 15 is changed by adjusting the rotation angle of the output shaft 701 of the rotary motor 70, and the stitch length value of the sewing machine is adjusted.

[0162] The control method of Embodiment Two comprises the following steps:

[0163] S1, presetting N fabric thickness intervals, N sewing modes and N positioning angle values between the main shaft and the presser foot eccentric wheel in the controller of the sewing machine, N being a natural number greater than 1; the nth fabric thickness interval, the nth sewing mode and the nth positioning angle value correspond to each other, n being a natural number less than or equal to N.

[0164] S2, judging whether the presser foot needs to be lifted according to the current thickness value of the fabric; when the height of the presser foot 29 needs to be adjusted, the output shaft of the rotary motor 70 rotates from the origin to a certain rotation angle value in the presser foot lifting area W1, the first driving part 211 of the presser foot lifting cam 21 is in contact with the presser foot roller 22, and the rotary motor 70 can drive the presser foot 29 to lift through the presser foot lifting assembly. Then, the current thickness value of the fabric at the needle is obtained in real time according to the fabric thickness detection sensor signal arranged at the needle plate, and it is judged according to the current thickness value that the fabric is in the nth fabric thickness interval and the nth sewing mode should be executed; at the same time, the positioning angle value between the current main shaft 41 and the presser foot eccentric wheel 43 is obtained, and if the current positioning angle value is the same as the nth positioning angle value, the sewing machine works normally; if not, step S3 is entered.

[0165] S3, the main shaft motor 40 first drives the main shaft 41 to rotate to a specified position, and then the output shaft of the rotary motor 70 rotates from the current rotation angle value to the feeding timing adjustment area W2, at this time the second driving part 311 of the feeding timing adjustment cam 31 is in contact with the feeding timing adjustment roller 36, and the rotary motor 70 drives the limiting part 33 to approach the presser foot eccentric wheel 43 through the feeding timing adjustment assembly, when the limiting part 33 abuts against the outer periphery of the presser foot eccentric wheel 43 but has not yet entered the groove 432, the rotary motor 70 occurs to be blocked and feeds back to the controller, the controller controls the main shaft motor 40 to drive the main shaft 41 to rotate at a speed less than or equal to 200 r / min, the main shaft 41 drives the presser foot eccentric wheel 43 to rotate synchronously, until the groove 432 is opposite to the limiting part 33, the rotary motor 70 is blocked, the blocking signal disappears, the rotary motor 70 drives the limiting part 33 to enter the groove 432, and the presser foot eccentric wheel 43 is separated from the main shaft 41.

[0166] S31, the rotary motor 70 and the main shaft motor 40 stop working, and the current angle value of the main shaft 41 is read and set as the adjustment starting angle value.

[0167] S4, the main shaft motor 40 drives the main shaft 41 to rotate an angle value x starting from the starting angle value as a starting point, so that the positioning angle value between the current main shaft 41 and the lifting tooth eccentric wheel 43 is the same as the nth positioning angle value, and the adjustment of the feeding sequence is completed.

[0168] S5, the output shaft of the rotary motor 70 rotates from the current rotation angle value to a certain rotation angle value in the needle spacing adjustment area W3, the third driving part 811 is in contact with the needle spacing adjustment roller 82, the rotary motor 70 drives the feeding swing seat 15 to rotate an angle around the feeding support shaft 100 through the needle spacing adjustment assembly, thereby changing the needle spacing value of the sewing machine, and keeping the needle spacing values before and after adjusting the feeding sequence consistent.

[0169] The rotation angle of the output shaft of the rotary motor 70 can be defined as:

[0170]

[0171] Wherein, is the output shaft rotation angle of the rotary motor 70 to keep the needle spacing value unchanged; x is the angle change value of the main shaft in step S4, -30°≤x≤30°; f'(x) is the needle spacing compensation function about the main shaft angle change value x, which is obtained according to calculation or self-definition; k is a constant; is the output shaft rotation angle of the rotary motor 70 to realize the needle spacing value before adjusting the feeding sequence; is the rotary motor angle function about which is obtained according to calculation or self-definition.

[0172] S6, the output shaft 701 of the rotary motor 70 keeps the current rotation angle value, the panel displays the identification of the nth sewing mode, and the sewing machine starts working;

[0173] S7, when the fabric thickness detection sensor detects the change of the current thickness value of the sewing material at the needle, the above steps S2, S3, S4, S5 and S6 are repeated in turn.

[0174] The above only describes the preferred embodiments of the present application, and it should be pointed out that for ordinary skilled in the art, without departing from the technical principles of the present application, a number of improvements and replacements can be made, which should be considered as the protection scope of the present application.

Claims

1. A control method of a sewing machine including a spindle motor, a spindle that is rotated by the spindle motor, a headstock, a feed dog that is installed on the headstock, and a dog lifting assembly for connecting the spindle and the headstock, characterized by, The sewing machine further comprises a rotary motor, a lifting tooth clutch assembly, and a fabric feeding timing adjustment assembly connected between the rotary motor and the lifting tooth clutch assembly; a lifting tooth eccentric wheel in the lifting tooth assembly is connected with the main shaft through the lifting tooth clutch assembly, a groove is formed on the outer periphery of the lifting tooth eccentric wheel, and the fabric feeding timing adjustment assembly comprises a limiting piece facing the lifting tooth eccentric wheel; when the sewing machine is normally operated, the limiting piece is away from the lifting tooth eccentric wheel, the lifting tooth clutch assembly allows power transmission between the main shaft and the lifting tooth eccentric wheel, and the main shaft can drive the lifting tooth eccentric wheel to rotate synchronously; when the fabric feeding timing needs to be adjusted, the rotary motor drives the limiting piece to approach the lifting tooth eccentric wheel and enter the groove, the lifting tooth clutch assembly blocks the power transmission between the main shaft and the lifting tooth eccentric wheel, the main shaft and the lifting tooth eccentric wheel rotate relatively, the positioning angle between the main shaft and the lifting tooth eccentric wheel is changed, and then the fabric feeding timing is changed; the lifting tooth clutch assembly comprises a ratchet wheel fixed on the main shaft, a sliding groove formed on the end face of the lifting tooth eccentric wheel, and a sliding piece in sliding fit with the sliding groove, and the sliding piece is provided with a toothed portion; when the sewing machine is normally operated, the toothed portion is engaged with the ratchet wheel; when the fabric feeding timing is adjusted, the toothed portion is separated from the ratchet wheel; the fabric feeding timing adjustment assembly comprises a fabric feeding timing adjustment lever hinged to the sewing machine housing and a fabric feeding timing adjustment cam arranged on the output shaft of the rotary motor, one end of the fabric feeding timing adjustment lever is hinged with a fabric feeding timing adjustment roller, the fabric feeding timing adjustment roller abuts against the fabric feeding timing adjustment cam, and the other end of the fabric feeding timing adjustment lever is connected with the limiting piece; the fabric feeding timing adjustment cam comprises a second driving portion formed by a variable-diameter surface and a second avoiding portion formed by an equal-diameter surface; the control method comprises the following steps: S1, presetting N fabric thickness intervals, N sewing modes and N positioning angle values between the main shaft and the lifting tooth eccentric wheel in the controller of the sewing machine, N is a natural number greater than 1, the nth fabric thickness interval, the nth sewing mode and the nth positioning angle value correspond to each other, n is a natural number less than or equal to N; S2, acquiring the current thickness value of the fabric at the needle in real time, determining whether the current thickness value is in the nth fabric thickness interval and the nth sewing mode should be executed according to the current thickness value; meanwhile, the positioning angle value between the current main shaft and the lifting tooth eccentric wheel is acquired, if the current positioning angle value is the same as the nth positioning angle value, the sewing machine is normally operated; if not, step S3 is entered; S3, the second driving portion is in touch fit with the fabric feeding timing adjustment roller, the rotary motor drives the limiting piece to approach the lifting tooth eccentric wheel, when the limiting piece abuts against the lifting tooth eccentric wheel but has not entered the groove, the rotary motor is blocked and feeds back to the controller, the controller controls the main shaft motor to drive the main shaft to rotate until the groove is opposite to the limiting piece, the blocking signal disappears, and the rotary motor drives the limiting piece to enter the groove. S4, the main shaft motor drives the main shaft to rotate until the current positioning angle value between the main shaft and the tooth lifting eccentric wheel is the same as the nth positioning angle value.

2. The control method according to claim 1, characterized by, The sewing machine further comprises a feed motor and a feed assembly connected between the feed motor and the needle frame. The control method further comprises a step of adjusting the output rule of the feed motor according to the parameter setting in the nth sewing mode, so that the phase difference between the X-direction movement track and the Y-direction movement track of the feed needle remains unchanged.

3. The control method according to claim 1, characterized by, The method further comprises a step S5 of adjusting the stitch length value of the sewing machine, so that the stitch length values before and after the feed timing adjustment remain unchanged.

4. The control method according to claim 3, characterized by, The sewing machine further comprises a feed assembly connected between the main shaft and the needle frame, the feed assembly comprising a feed swing seat rotating around a feed support shaft, the position of the feed support shaft being fixed, the feed swing seat being connected to the output shaft of the rotary motor through a stitch length adjustment assembly, the angle of the feed swing seat determining the stitch length value of the sewing machine. In step S5, the rotation angle of the output shaft of the rotary motor is adjusted, the angle of the feed swing seat is changed, and the stitch length value of the sewing machine is adjusted.

5. The control method according to claim 3, characterized by, The sewing machine further comprises a feed motor and a feed assembly connected between the feed motor and the needle frame. In step S5, the output rule of the feed motor is adjusted, the X-direction movement track of the feed needle is changed, and the stitch length value of the sewing machine is adjusted.

6. The control method according to claim 1, characterized by After step S3 and before step S4, the method further comprises a step S31 of stopping the rotary motor and the main shaft motor, reading the current angle value of the main shaft, and setting the current angle value as the adjustment starting angle value.

7. The control method according to claim 1, characterized by, The sewing machine further comprises a presser foot lifting assembly connected to the output shaft of the rotary motor and the presser foot. The above step S2 further comprises determining whether the presser foot needs to be lifted according to the current thickness value of the sewing material, and when the presser foot height needs to be adjusted, the output shaft of the rotary motor rotates to drive the presser foot lifting assembly to lift the presser foot.

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