Medium pressure foot mechanism control method and medium pressure foot mechanism

Abstract

A medium pressure foot mechanism control method and medium pressure foot mechanism, including the following steps: the control unit controls the rotation of the main shaft motor, medium pressure foot motor and feeding motor according to the target pattern parameters to obtain the target sewing stitch; the control unit obtains the given pressure angle range from the expected pressure angle range according to the cloth thickness and sewing speed; the control unit obtains the given medium pressure foot stroke from the expected medium pressure foot stroke according to the cloth thickness and medium pressure foot height; the medium pressure foot mechanism realizes the follow-up up-down movement of the medium pressure foot through the motor drive crank, fish eye joint A and B, connecting rod, pressure rod guide frame and other components; the motor is fixed through the support, the output shaft is connected with the drive crank, the drive crank drives the fish eye joint A to be connected with the connecting rod, and the motion is transmitted to the pressure rod and the medium pressure foot; the pressure rod guide frame plays a guiding role and limits the rotation of the pressure rod; the inductive plate is arranged on the drive crank, and when the medium pressure foot is lifted to the highest point, the sensor can sense the inductive plate to realize position feedback.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of presser foot in sewing machine, and particularly relates to a presser foot mechanism control method and a presser foot mechanism. BACKGROUND

[0002] The presser foot mechanism, also known as the presser foot device, is an important component of a sewing machine, mainly used to control the lifting and placing of the presser foot. It is usually located above the needle plate of the sewing machine and serves to provide appropriate pressure to the fabric, ensuring that the fabric does not become excessively loose, slide, or deform during the sewing process.

[0003] The main function of the presser foot is to help control the flatness of the fabric and the quality of the stitching by adjusting the pressure of the presser foot. It usually works in conjunction with the presser foot mechanism by adjusting the height or weight of the presser foot to adapt to fabrics of different thicknesses or textures. For example, for thicker fabrics, higher pressure is needed to maintain the stability of the fabric; while for thin or slippery fabrics, the pressure needs to be smaller to avoid the fabric being deformed or being stretched too much.

[0004] The working requirements of the presser foot mechanism include the following aspects:

[0005] Apply uniform pressure: ensure that the fabric passes through the sewing machine stably during sewing;

[0006] Adjust the pressure and the lower dead point height of the presser foot to adapt to fabrics of different thicknesses and different materials, avoiding problems such as skipping stitches and broken threads;

[0007] Avoid fabric deformation: by reasonable pressure and lower dead point height of the presser foot, prevent the fabric from being deformed due to excessive compression during sewing;

[0008] The commonly used presser foot mechanism at present is generally driven by a main shaft connected to a main shaft motor to drive the presser foot up and down, and another motor to drive the change of the lower dead point of the presser foot; the problems of this mechanism are: complex structure, unable to change the follow-up stroke in motion, etc., which need to be solved urgently. SUMMARY

[0009] The purpose of the present application is to provide a presser foot mechanism control method, comprising the following steps: a control unit controls the rotation of a main shaft motor, a presser foot motor, and a feeding motor according to target pattern parameters, and the main shaft motor, the presser foot motor, and the feeding motor are matched with respective independent time sequences and input parameters to obtain a target sewing stitch;

[0010] The control unit obtains target pattern parameters; the control unit obtains a given pressure angle range from an expected pressure angle range according to fabric thickness and sewing speed;

[0011] The control unit obtains a given presser foot stroke from an expected presser foot stroke according to the cloth thickness and the presser foot height;

[0012] The presser foot height is the lower limit height of the presser foot follow-up;

[0013] The presser foot stroke is the difference between the highest point and the lowest point of the presser foot in follow-up;

[0014] The given press angle range is the main shaft motor angle range from the control unit issuing a start pressing instruction to the control unit issuing a complete lifting instruction;

[0015] The expected press angle range is the main shaft motor angle range from the expected press mechanism starting to press to completing lifting.

[0016] The technical scheme provided by the application also has the following technical features:

[0017] Preferably, in an embodiment of the application, the pattern target parameters include stitch speed and presser foot height in the pattern.

[0018] Preferably, in an embodiment of the application, the pattern parameters at least include data of needle spacing, stitch speed, presser foot height, and thread tension.

[0019] Preferably, in an embodiment of the application, the pattern parameters further include one or more combinations of data of needle width, pattern type, pattern density, pattern length, pattern alignment, pattern direction, pattern repetition number, reverse pattern, elastic pattern, and automatic pattern adjustment.

[0020] Preferably, in an embodiment of the application, different cloth thicknesses and stitch speeds are preset, and corresponding expected press angle ranges are matched.

[0021] Preferably, in an embodiment of the application, the given press angle range includes the pressing process and the lifting process of the presser foot.

[0022] Preferably, in an embodiment of the application, different cloth thicknesses and presser foot heights are preset, and corresponding expected presser foot strokes are matched.

[0023] Preferably, in an embodiment of the application, the instructions of the presser foot motor angle are given through a time sequence curve of the presser foot motor angle.

[0024] Preferably, in an embodiment of the application, the presser foot stroke is realized through the angle of the presser foot motor, and the lowest point motor angle and the highest point motor angle of the presser foot are determined according to the cloth thickness and the presser foot height.

[0025] Settings:

[0026] Angle A, representing the main shaft motor angle when the control unit sends the start pressing down command;

[0027] Angle B, representing the main shaft motor angle when the control unit sends the end pressing down command;

[0028] Angle C, representing the main shaft motor angle when the control unit sends the start lifting up command;

[0029] Angle D, representing the main shaft motor angle when the control unit sends the end lifting up command;

[0030] Angle E, representing the main shaft motor angle when the presser foot actually reaches the highest point;

[0031] Angle F, representing the main shaft motor angle when the presser foot actually reaches the lowest point;

[0032] Angle G, representing the main shaft motor angle when the presser foot is expected to reach the highest point;

[0033] Angle H, representing the main shaft motor angle when the presser foot is expected to reach the lowest point;

[0034] Angle I, representing the presser foot motor angle when the control unit sends the highest point of the presser foot;

[0035] Angle J, representing the presser foot motor angle when the control unit sends the lowest point of the presser foot.

[0036] Preferably, in an embodiment of the present application, the lead angle K represents the difference between the main shaft motor angle when the presser foot is expected to reach the highest point and the main shaft motor angle when the control unit sends the end lifting up command; that is, the lead angle K = Angle G - Angle D;

[0037] The lead angle L represents the difference between the main shaft motor angle when the presser foot is expected to reach the lowest point and the main shaft motor angle when the control unit sends the end pressing down command; that is, the lead angle L = Angle H - Angle B.

[0038] Preferably, in an embodiment of the present application, the main shaft motor is used to control the thread picking and thread hooking of the needle;

[0039] The presser foot motor is used to control the pressing of the presser foot;

[0040] The feeding motor is used to control the X / Y axis movement for feeding;

[0041] The main shaft motor, the presser foot motor, and the feeding motor are independently controlled, so that the timing and input parameters can be adjusted during the sewing process.

[0042] Preferably, in an embodiment of the present application, the control unit completes the sewing operation through the main shaft motor, the presser foot motor, and the feeding motor, so that the presser foot completes the corresponding action.

[0043] Preferably, in one embodiment of the present application, input parameters including fabric thickness, number of layers, etc. are automatically adjusted during the sewing process.

[0044] Preferably, in one embodiment of the present application, the speed reduction sewing area adjusts the presser foot synchronization, bottom dead point height and follow-up stroke.

[0045] Preferably, in one embodiment of the present application, during the sewing process, the control unit reads the pattern information and determines that the sewing speed set in a certain section is significantly reduced, and the set middle presser foot height is significantly increased, thereby determining that the fabric is sewn to an overly thick area;

[0046] If the sewing speed is only set to decrease in the pattern, and the height of the intermediate presser foot remains unchanged, it cannot be determined that the sewing has reached an overly thick area;

[0047] When it is judged to be too thick, the control program automatically advances Angle A and Angle B according to the control parameters preset in the program based on the sewing speed and the height of the middle presser foot; that is, by advancing the spindle motor angle at which the control unit sends a start pressing command and the spindle motor angle at which the control unit sends an end pressing command, the desired spindle motor angle at which the middle presser foot reaches the lowest point is achieved.

[0048] Preferably, in one embodiment of the present application, according to the middle presser foot height provided, adjust angle I and angle J, and simultaneously increase the difference between angle J and angle I. That is, increase the middle presser foot height, and increase the middle presser foot stroke.

[0049] Preferably, in one embodiment of the present application, the adjustment of angle I and angle J is performed according to the comparison of different middle presser foot heights and middle presser foot motor angles set in advance in the control program.

[0050] The above-mentioned control method for a middle presser foot mechanism is applied to the middle presser foot mechanism. A motor is arranged on a housing through a bracket. The output shaft of the motor is connected to one end of a driving crank. The other end of the driving crank is connected to a fisheye joint A through an axial screw. The fisheye joint A is threadedly connected to one end of a connecting rod and is locked by a nut A. The other end of the connecting rod is threadedly connected to a fisheye joint B and is locked by a nut B.

[0051] Fisheye joint B is connected to the pressure rod guide frame via locking screws and locking nuts. The pressure rod guide frame is set on the pressure rod, and the pressure rod moves up and down in the pressure rod bushing. The middle presser foot is fixed to the lower end of the pressure rod. The pressure rod guide frame guides and limits the radial rotation of the pressure rod.

[0052] The driving crank is provided with an induction plate; the sensor is fixed on the bracket; when the presser foot is raised to the highest point, the induction plate is above the sensor sensing area;

[0053] When the motor rotates clockwise, it drives the driving crank to rotate clockwise around the motor shaft; the driving crank then drives the fisheye joint A to lift, and transmits it in sequence to the connecting rod, fisheye joint B, pressure rod guide, pressure rod, and intermediate presser foot, so that the intermediate presser foot is lifted; conversely, the motor rotates counterclockwise and the intermediate presser foot descends; the motor swings back and forth, and when the intermediate presser foot moves up and down at a certain amplitude, the intermediate presser foot is followed; the lower limit height of the following motion can be changed, and the following amplitude, that is, the following stroke, can also be changed; when sewing is finished, the intermediate presser foot is lifted to the preset highest point; when the intermediate presser foot is lifted to the highest point, the sensor should be able to sense the induction plate.

[0054] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0056] Figure 1 A three-dimensional middle presser foot mechanism of the present invention Figure 1 ;

[0057] Figure 2 A three-dimensional middle presser foot mechanism of the present invention Figure 2 ;

[0058] Figure 3 Schematic diagram of a method for controlling a middle presser foot mechanism of the present invention;

[0059] Figure 4 A timing diagram of the angle of the middle presser foot motor of a middle presser foot mechanism control method of the present invention;

[0060] Figure 5 Flowchart of a method for controlling a middle presser foot mechanism of the present invention;

[0061] Components in the picture:

[0062] 1. Bracket

[0063] 2. Motor

[0064] 3. Drive crank

[0065] 4. Sensors

[0066] 5. Induction board

[0067] 6. Fisheye connector A

[0068] 7. Nut A

[0069] 8. Connecting rod

[0070] 9. Locking screws

[0071] 10. a presser bar guide

[0072] 11. a presser bar

[0073] 12. a presser bar bushing

[0074] 13. a presser bar foot

[0075] 14. a machine housing

[0076] 15. a shaft set screw

[0077] 16. a castle nut

[0078] 17. a fish eye fitting B

[0079] 18. a nut B. DETAILED DESCRIPTION

[0080] The specific embodiments of the present application will be further described with reference to the drawings. These embodiments are illustrative only and are not intended to limit the present application.

[0081] In the description of the present application, it should be noted that the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0082] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0083] In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0084] As Figure 1 , 2 A presser foot mechanism of a sewing machine, the use process is as follows:

[0085] First, the motor 2 is fixed on the casing 14 through the support 1, and the output shaft of the motor 2 is provided with a driving crank 3, the other end of the driving crank 3 is connected with the fish eye joint A6 through the shaft position screw 15. The fish eye joint A6 is threadedly connected with the connecting rod 8, and is locked through the nut A7. The connecting rod 8 is provided with threads at both ends, and the other end is connected with the fish eye joint B17, and is locked through the nut B18. The fish eye joint B17 is connected with the pressure rod guide 10 through the locking screw 9 and the locking nut 16. The pressure rod guide 10 is fixed on the pressure rod 11, the pressure rod 11 moves up and down in the pressure rod bushing 12, and the lower end of the pressure rod 11 is fixed with the middle pressure foot 13. The pressure rod guide 10 plays a role of guiding and limiting the radial rotation of the pressure rod 11.

[0086] The driving crank 3 is fixed with a sensing plate 5. The sensor 4 is fixed on the support 1. When the pressure foot is lifted to the highest point, the sensing plate 5 is above the sensing area of the sensor 4. The sensing plate 5, the sensor 4 and other related sensing components are not necessary for the scheme.

[0087] According to the scheme, Figure 1 When the motor 2 rotates clockwise, the driving crank 3 is driven to rotate clockwise around the shaft of the motor 2. The driving crank 3 drives the fish eye joint A6 to lift, and sequentially transmits to the connecting rod 8, the fish eye joint B17, the pressure rod guide 10, the pressure rod 11 and the middle pressure foot 13, so that the middle pressure foot 13 is lifted. Conversely, when the motor 2 rotates counterclockwise, the middle pressure foot 13 is lowered. When the motor 2 reciprocates, the middle pressure foot 13 moves up and down by a certain amplitude, thereby forming the follow-up of the middle pressure foot 13. The lower limit height of the follow-up can be changed, and the amplitude of the follow-up, i.e. the follow-up stroke, can also be changed. When the sewing is finished, the middle pressure foot 13 is lifted to the preset highest point. When the middle pressure foot 13 is lifted to the highest point, the sensor 4 should be able to sense the sensing plate 5.

[0088] The application provides a control method and structure of a middle pressure foot mechanism, which has simple structure, variable stroke in motion, low motor load and simple parts and installation.

[0089] According to the scheme, Figure 3 The control method of the middle pressure foot mechanism of the application controls the rotation of the main shaft motor, the middle pressure foot motor and the feeding motor according to the pattern, so as to control the sewing stitches;

[0090] The control unit is an electronic control system, which is composed of a microprocessor, a sensor and a driving circuit, and has higher intelligence and automation. The control unit of the electronic sewing machine is based on a microcontroller such as MCU, and complex logic control is realized through programming.

[0091] The main shaft motor controls the thread picking and hooking of the shuttle, the medium pressure foot motor controls the material pressing of the medium pressure foot, and the feeding motor controls the X / Y axis movement for feeding; since the three are independently controlled, the timing and the like can be adjusted during the sewing process without stopping; the sewing machine can automatically adjust according to the thickness and the number of layers of the fabric during the sewing process, thereby improving the quality of the sewing stitches;

[0092] Specifically, the control method of the medium pressure foot mechanism comprises: first, obtaining the sewing speed and the medium pressure foot height in the pattern; second, determining the pressing angle range according to the fabric thickness and the sewing speed; third, determining the medium pressure foot stroke according to the fabric thickness and the medium pressure foot height; fourth, controlling the main shaft motor and the medium pressure foot motor according to the above information.

[0093] First, the sewing speed and the medium pressure foot height in the pattern are obtained. The data of the pattern parameters should at least include stitch length, sewing speed, medium pressure foot height, thread tension parameters and the like, and the above parameters can be set in sections. The sewing speed and the medium pressure foot height in the pattern are determined according to the material of the fabric, the thickness of a single layer, the number of layers and the like. The medium pressure foot height is the lower limit height of the medium pressure foot. For example, when sewing a 3-layer denim fabric, the medium pressure foot height is set to 2.5 mm, and the sewing speed is 3000 rpm; when sewing a 10-layer denim fabric, the medium pressure foot height is set to 7 mm, and the sewing speed is 1500 rpm.

[0094] The pattern parameters can also include needle width, pattern type, pattern density, pattern length, pattern alignment, pattern direction, pattern repetition number, reverse pattern, elastic pattern, automatic pattern adjustment and the like.

[0095] Second, the given pressing angle range is obtained according to the fabric thickness and the sewing speed. In the program, different fabric thicknesses and sewing speeds corresponding to the expected pressing angle range are preset. Thus, during execution, the given pressing angle range is obtained from the expected pressing angle range by the fabric thickness and the sewing speed.

[0096] When the motor driving mechanism moves, it needs a certain time to complete the response after the control unit issues an instruction. Therefore, the pressing angle range is defined as the given pressing angle range.

[0097] Compared with the expected pressing angle range, the given pressing angle range corresponds to the main shaft motor angle of the corresponding instruction issued by the control unit, and the expected pressing angle range corresponds to the expected main shaft motor angle of the pressing.

[0098] Therefore, the given pressing angle range includes the pressing process and the lifting process, which represents the main shaft motor angle range from the start of the pressing instruction issued by the control unit to the completion of the lifting instruction issued by the control unit.

[0099] The expected pressing angle range represents the main shaft motor angle range from the start of the pressing to the completion of the lifting of the expected pressing mechanism.

[0100] Thirdly, the middle presser stroke is determined according to the cloth thickness and the middle presser height. In the program, different cloth thicknesses and middle presser heights correspond to different middle presser strokes. Thus, during execution, the middle presser stroke is determined according to the cloth thickness and the middle presser height.

[0101] The middle presser stroke refers to the difference between the highest point and the lowest point of the middle presser during follow-up. Corresponding to the angle of the middle presser motor, the lowest point motor angle and the highest point motor angle of the middle presser need to be determined according to the cloth thickness and the middle presser height. Due to the overshoot phenomenon of the motor under high-speed reciprocating swing, the actual lifting of the presser to the highest point is just the beginning of the next pressing.

[0102] As shown in the following Figure 4 As shown in the following Figure 4 , the middle presser motor angle is given according to the curve. The actual angle is not equal to the given motor angle. The actual highest point angle is greater than the given highest point angle, and the actual lowest point angle is less than the given lowest point angle. And the main shaft angles corresponding to reaching the given lowest point angle and reaching the actual lowest point angle are different.

[0103] Thus, the following can be set:

[0104] Angle A represents the main shaft motor angle at which the control unit issues a start pressing instruction;

[0105] Angle B represents the main shaft motor angle at which the control unit issues an end pressing instruction;

[0106] Angle C represents the main shaft motor angle at which the control unit issues a start lifting instruction;

[0107] Angle D represents the main shaft motor angle at which the control unit issues an end lifting instruction;

[0108] Angle E represents the main shaft motor angle at which the middle presser actually reaches the highest point;

[0109] Angle F represents the main shaft motor angle at which the middle presser actually reaches the lowest point;

[0110] Angle G represents the main shaft motor angle at which the middle presser is expected to reach the highest point;

[0111] Angle H represents the main shaft motor angle at which the middle presser is expected to reach the lowest point;

[0112] Angle I represents the middle presser motor angle of the highest point of the middle presser given by the control unit;

[0113] Angle J represents the middle presser motor angle of the lowest point of the middle presser given by the control unit;

[0114] The advance angle K represents the difference between the spindle motor angle at which the presser foot reaches its highest point and the spindle motor angle at which the control unit issues the end-of-lift command. That is, the advance angle K = angle G - angle D.

[0115] The advance angle L represents the difference between the spindle motor angle at which the intermediate presser foot reaches its lowest point and the spindle motor angle at which the control unit issues the end-pressing command. That is, the advance angle L = angle H - angle B.

[0116] During execution, under different speed settings, the advance angle K and advance angle L are different. The higher the spindle speed, the greater the advance amount.

[0117] The fourth step is to control the presser foot motor and the spindle motor according to the above information.

[0118] Specifically, this control method should also include the following specific control methods:

[0119] Adjust the presser foot's synchronization, bottom dead center height, and follow-up stroke in the slowed-down sewing area. Take the opening of a pocket machine as an example. The opening is formed by folding and sewing multiple layers of fabric. During the downward pressing process, the presser foot exerts a pressing force on the fabric, compacting it. As the needle moves downward, penetrates the fabric, and then returns to its highest point, the presser foot also presses down, contacts the fabric, reaches its lowest point, and then rises and clears the fabric to its highest point. During this process, if the needle penetrates the fabric but the presser foot has not yet reached its lowest point, and the feed mechanism is still feeding, problems such as fabric shifting, skipped stitches, thread breakage, needle bending, and even needle breakage can occur. To address this issue, lower the presser foot in advance and set the bottom dead center height and follow-up stroke appropriately. This ensures that the fabric is pressed into place and, after feeding begins, the presser foot is elevated above the fabric to prevent dragging.

[0120] During the sewing process, the control unit first reads the pattern information and determines whether the set sewing speed in a certain section is significantly reduced and the set presser foot height is significantly increased. This determines that the fabric has been sewn into an overly thick area. If only the set sewing speed in the pattern is reduced and the set presser foot height remains unchanged, it cannot be determined that the fabric has been sewn into an overly thick area.

[0121] Then, if the seam is judged to be too thick, the control program automatically advances Angle A and Angle B according to the preset control parameters based on the sewing speed and the height of the middle presser foot. That is, by advancing the spindle motor angle when the control unit issues the start press command and the spindle motor angle when the control unit issues the end press command, the spindle motor angle (angle H) at which the middle presser foot reaches the lowest point is advanced.

[0122] Secondly, according to the middle presser feet height provided, adjust angle I and angle J, and simultaneously adjust the difference between angle J and angle I. That is, increase the middle presser feet height, and increase the middle presser feet stroke. Said adjustment is performed according to the different middle presser feet heights and middle presser feet motor angles provided in advance in the control program.

[0123] Finally, the presser foot motor and the spindle motor are controlled according to the above information.

[0124] The above judgment process is as follows Figure 5 The technical solution provided by this application has the following characteristics:

[0125] 1. The mechanical structure is simple and direct, the motor load is light, and the process requirements are low;

[0126] 2. Enable the sewing machine to automatically adjust according to the thickness and number of layers of fabric during the sewing process, thereby improving the quality of sewing stitches;

[0127] The present application provides a mechanical structure of a middle presser foot, connected by upper and lower fisheye joints; and a control method of the middle presser foot, including a method for handling excessive thickness.

[0128] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A method for controlling a middle presser foot mechanism, characterized in that: The steps include: The control unit controls the rotation of the main shaft motor, the intermediate presser motor and the feed motor according to the target pattern parameters, and the main shaft motor, the intermediate presser motor and the feed motor are equipped with independent timing and input parameters to obtain the target sewing stitch; The control unit obtains the target parameters of the pattern; the control unit obtains the given pressing angle range from the expected pressing angle range according to the fabric thickness and sewing speed; The control unit obtains a given presser foot stroke from an expected presser foot stroke according to the fabric thickness and the presser foot height; The intermediate presser foot height is the lower limit height of the intermediate presser foot's follow-up movement; Intermediate presser foot stroke: the difference between the highest point and the lowest point of the intermediate presser foot when it moves; The given pressing angle range is: the spindle motor angle range from the time the control unit issues the start pressing command to the time the control unit issues the completion lifting command; The expected pressing angle range is the spindle motor angle range from when the pressing mechanism starts pressing down to when it finishes lifting up. Pattern target parameters, including sewing speed and presser foot height in the pattern; The stroke of the intermediate presser foot is achieved by the angle of the intermediate presser foot motor. The motor angles at the lowest and highest points of the intermediate presser foot are determined according to the thickness of the fabric and the height of the intermediate presser foot. set up: Angle A represents the spindle motor angle at which the control unit issues the start-press command; Angle B represents the spindle motor angle at which the control unit issues the end-pressing command; Angle C represents the spindle motor angle at which the control unit issues the start lift command; Angle D represents the spindle motor angle at which the control unit issues the command to end the lift; Angle E indicates the spindle motor angle when the intermediate presser foot actually reaches the highest point; Angle F indicates the spindle motor angle when the intermediate presser foot actually reaches the lowest point; Angle G, which indicates the spindle motor angle at which the presser foot is expected to reach its highest point; Angle H indicates the spindle motor angle at which the intermediate presser foot is expected to reach the lowest point; Angle I represents the angle of the presser foot motor at the highest point of the presser foot given by the control unit; Angle J, represents the angle of the presser foot motor at the lowest point of the presser foot given by the control unit; The advance angle K represents the difference between the spindle motor angle at which the intermediate presser foot is expected to reach its highest point and the spindle motor angle at which the control unit issues the command to end the lifting operation. That is, the advance angle K = angle G - angle D. The advance angle L represents the difference between the spindle motor angle at which the intermediate presser foot reaches the lowest point and the spindle motor angle at which the control unit issues the end-pressing command; that is, the advance angle L = angle H - angle B; Adjust presser foot synchronization, bottom dead center height and follow-up stroke in the reduced-speed sewing area; During the sewing process, the control unit reads the pattern information and determines that the sewing speed set in a certain section is significantly reduced, and at the same time the set middle presser foot height is significantly increased, thereby determining that the fabric is sewn to an overly thick area; If the sewing speed is only set to decrease in the pattern, and the height of the intermediate presser foot remains unchanged, it cannot be determined that the sewing has reached an overly thick area; When it is judged to be too thick, the control program automatically advances Angle A and Angle B according to the control parameters preset in the program based on the sewing speed and the height of the middle presser foot; that is, by advancing the spindle motor angle at which the control unit sends a start pressing command and the spindle motor angle at which the control unit sends an end pressing command, the desired spindle motor angle at which the middle presser foot reaches the lowest point is achieved.

2. A method for controlling a middle presser foot mechanism according to claim 1, characterized in that: The cycle is executed to obtain the pattern parameters including at least the stitch length, sewing speed, presser foot height and thread tension data.

3. A method for controlling a middle presser foot mechanism according to claim 2, characterized in that: The pattern parameters also include one or a combination of data on needle width, pattern type, pattern density, pattern length, pattern alignment, pattern direction, pattern repetition times, reverse pattern, elastic pattern, and automatic pattern adjustment.

4. A method for controlling a middle presser foot mechanism according to claim 1, characterized in that: Preset different fabric thicknesses and sewing speeds, with corresponding desired pressing angle ranges; The given pressing angle range includes the pressing and lifting processes of the presser foot; Preset the expected presser foot stroke corresponding to different fabric thicknesses and presser foot heights; The angle command of the intermediate presser motor is given through the timing curve of the intermediate presser motor angle.

5. A method for controlling a middle presser foot mechanism according to claim 1, characterized in that: The spindle motor is used to control the thread picking and hook hooking; The middle presser foot motor is used to control the middle presser foot to press the material; Feeding motor, used to control X / Y axis movement for feeding; The spindle motor, presser foot motor and feed motor are controlled independently, so that the timing and input parameters can be adjusted during the sewing process; The control unit completes the sewing operation through the main shaft motor, the intermediate presser foot motor and the feed motor, so that the intermediate presser foot completes the corresponding action; Input parameters include fabric thickness and number of layers, which are automatically adjusted during the sewing process.

6. A method for controlling a middle presser foot mechanism according to claim 1, characterized in that: Adjust Angle I and Angle J according to the set intermediate presser foot height, and at the same time increase the difference between Angle J and Angle I; that is, increase the intermediate presser foot height and increase the intermediate presser foot stroke.

7. A method for controlling a middle presser foot mechanism according to claim 1, characterized in that: Adjust angle I and angle J: execute according to the different presser foot heights and presser foot motor angles set in advance in the control program.

8. A middle presser foot mechanism, using the middle presser foot mechanism control method according to any one of claims 1 to 7, characterized in that: The motor (2) is arranged on the housing (14) through the bracket (1); the output shaft of the motor (2) is connected to one end of the driving crank (3); the other end of the driving crank (3) is connected to the fisheye joint A (6) through the axial screw (15); the fisheye joint A (6) is threadedly connected to one end of the connecting rod (8) and is locked by the nut A (7); the other end of the connecting rod (8) is threadedly connected to the fisheye joint B (17) and is locked by the nut B (18); The fisheye joint B (17) is connected to the pressure rod guide frame (10) through a locking screw (9) and a locking nut (16); the pressure rod guide frame (10) is arranged on the pressure rod (11), the pressure rod (11) moves up and down in the pressure rod bushing (12), and the lower end of the pressure rod (11) is fixed with a middle presser foot (13); When the motor (2) rotates clockwise, the driving crank (3) rotates clockwise around the motor (2) shaft; the driving crank (3) then drives the fisheye joint A (6) to rise, and transmits the power to the connecting rod (8), the fisheye joint B (17), the pressure rod guide (10), the pressure rod (11), and the middle presser foot (13) in sequence, so that the middle presser foot (13) rises; on the contrary, when the motor (2) rotates counterclockwise, the middle presser foot (13) falls; the motor (2) swings back and forth, and when the middle presser foot (13) moves up and down at a certain amplitude, the middle presser foot (13) follows; the lower limit height of the following motion can be changed, and the amplitude of the following motion, i.e., the following motion stroke, can also be changed; when sewing is finished, the middle presser foot (13) is raised to a preset highest point; when the middle presser foot (13) is raised to the highest point, the sensor (4) should be able to sense the induction plate (5).

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