Middle presser foot mechanism control method and middle presser foot mechanism

Abstract

The invention discloses a medium presser foot mechanism control method and a medium presser foot mechanism, and the method comprises the following steps: a control unit controls the rotation of a main shaft motor, a medium presser foot motor and a feeding motor according to a target pattern parameter, and obtains a target sewing stitch; the control unit obtains a given material pressing angle range from the expected material pressing angle range according to the cloth thickness and the sewing speed; the control unit obtains a given middle presser foot stroke from the expected middle presser foot stroke according to the cloth thickness and the middle presser foot height; according to the middle presser foot mechanism, a motor drives a crank, fisheye connectors A and B, a connecting rod, a pressing rod guide frame and other assemblies, and follow-up vertical movement of a middle presser foot is achieved. A motor is fixed through a support, an output shaft is connected with a driving crank, and the driving crank drives a fisheye connector A to be connected with a connecting rod and transmits motion to a pressing rod and a middle pressing foot. The pressing rod guide frame plays a guiding role and limits rotation of the pressing rod. The induction plate is arranged on the driving crank, when the middle presser foot is lifted to the highest point, the sensor can sense the induction plate, and position feedback is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of a middle presser foot of a sewing machine, and in particular relates to a control method of a middle presser foot mechanism and the middle presser foot mechanism. Background Art

[0002] The middle presser foot mechanism, also known as the middle presser foot device, is an important part of the sewing machine, mainly used to control the lifting and lowering of the middle presser foot. It is usually located above the needle plate of the sewing machine, and its function is to provide appropriate pressure for the fabric to ensure that the fabric does not become excessively loose, slip or deform during the sewing process.

[0003] The main function of the middle 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 to adapt to fabrics of different thicknesses or textures by adjusting the height or weight of the presser foot. For example, for thicker fabrics, higher pressure is required to maintain the stability of the fabric; while for thin or slippery fabrics, less pressure is required to avoid the fabric being deformed or overstretched.

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

[0005] Apply even pressure: Ensure that the fabric moves steadily through the sewing machine during sewing;

[0006] By adjusting the pressure and the lower dead point height of the middle presser foot, it can adapt to fabrics of different thicknesses and materials to avoid problems such as skipped stitches and thread breakage;

[0007] Avoid fabric deformation: through reasonable pressure and lower dead point height of the middle presser foot, prevent the fabric from being over-pressed and causing problems such as fabric rushing during sewing;

[0008] The commonly used intermediate presser foot mechanism at present is generally driven by a main shaft connected to the main shaft motor to drive the presser foot to move up and down, and then another motor drives the change of the lower dead point of the presser foot; the problems existing in this mechanism include: complex structure, inability to change the follow-up stroke during movement, etc. These problems urgently need to be solved. Summary of the invention

[0009] The object of the present invention is to provide a method for controlling a middle presser mechanism, comprising the following steps: a control unit controls the rotation of a main shaft motor, a middle presser motor and a feeding motor according to target pattern parameters, and the main shaft motor, the middle presser motor and the feeding motor are equipped with independent timing and input parameters to obtain target sewing stitches;

[0010] 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 the sewing speed;

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

[0012] The middle presser foot height is the lower limit height of the middle presser foot following movement;

[0013] Intermediate presser foot stroke: the difference between the highest point and the lowest point of the intermediate presser foot when it moves;

[0014] The given pressing angle range is: the spindle motor angle range from when the control unit issues a start pressing command to when the control unit issues a completion lifting command;

[0015] The expected pressing angle range is: the expected spindle motor angle range from when the pressing mechanism starts pressing down to when it completes lifting.

[0016] A technical solution provided by this application also has the following technical features:

[0017] Preferably, in one embodiment of the present application, the pattern target parameters include the sewing speed and the middle presser foot height in the pattern.

[0018] Preferably, in one embodiment of the present application, the pattern parameters at least include data on stitch length, sewing speed, middle presser foot height, and thread tension.

[0019] Preferably, in one embodiment of the present application, the pattern parameters also include one or a combination of data of needle width, pattern type, pattern density, pattern length, pattern alignment, pattern direction, number of pattern repetitions, reverse pattern, elastic pattern, and automatic pattern adjustment.

[0020] Preferably, in one embodiment of the present application, different fabric thicknesses and sewing speeds are preset, with corresponding desired pressing angle ranges.

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

[0022] Preferably, in one embodiment of the present application, the expected middle presser foot stroke corresponding to different fabric thicknesses and middle presser foot heights are preset.

[0023] Preferably, in one embodiment of the present application, the instruction of the middle presser foot motor angle is given by a timing curve of the middle presser foot motor angle.

[0024] Preferably, in one embodiment of the present application, the stroke of the middle presser foot is realized by the angle of the middle presser foot motor, and the motor angle of the lowest point and the motor angle of the highest point of the middle presser foot are determined according to the thickness of the cloth and the height of the middle presser foot;

[0025] set up:

[0026] Angle A represents the spindle motor angle at which the control unit issues a start-press command;

[0027] Angle B represents the spindle motor angle at which the control unit issues the end-pressing command;

[0028] Angle C represents the spindle motor angle at which the control unit issues a start lift command;

[0029] Angle D, which indicates the spindle motor angle at which the control unit issues the command to end the lifting;

[0030] Angle E, represents the spindle motor angle when the intermediate presser foot actually reaches the highest point;

[0031] Angle F, which indicates the spindle motor angle when the intermediate presser foot actually reaches the lowest point;

[0032] Angle G, which indicates the spindle motor angle at which the presser foot is expected to reach the highest point;

[0033] Angle H, represents the spindle motor angle at which the presser foot is expected to reach the lowest point;

[0034] Angle I, represents the angle of the middle presser foot motor at the highest point of the middle presser foot given by the control unit;

[0035] Angle J represents the angle of the presser foot motor at the lowest point of the presser foot given by the control unit.

[0036] Preferably, in one embodiment of the present application, the advance angle K represents the spindle motor angle at which the desired middle presser foot reaches the highest point and the spindle motor angle at which the control unit issues an end-lifting instruction; that is, the advance angle K = angle G - angle D;

[0037] The advance angle L represents the spindle motor angle at which the intermediate presser foot is expected to reach the lowest point and the spindle motor angle at which the control unit issues an end-pressing instruction; that is, the advance angle L = angle H - angle B.

[0038] Preferably, in one embodiment of the present application, the spindle motor is used to control the thread picking of the piercing material and the thread hooking of the rotary hook;

[0039] Middle presser foot motor, used to control the middle presser foot to press materials;

[0040] Feeding motor, used to control X / Y axis movement for feeding;

[0041] The spindle motor, presser foot motor and feed motor are controlled independently, allowing the timing and input parameters to be adjusted during the sewing process.

[0042] Preferably, in one embodiment of the present application, the control unit completes the sewing operation through the main shaft motor, the middle presser foot motor, and the feeding motor, so that the middle 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, the bottom dead point height and the 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 height of the set middle presser foot is significantly increased, thereby determining that the fabric is sewn to an over-thick area;

[0046] If the sewing speed is only set to decrease in the pattern, and the height of the middle presser foot does not change, it cannot be determined that the sewing has reached an over-thick area;

[0047] When it is judged to be too thick, the control program automatically advances Angle A and Angle B according to the preset control parameters 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 made.

[0048] Preferably, in one embodiment of the present application, according to the set middle presser foot height, 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 middle presser foot mechanism control method is applied to the middle presser foot mechanism, a motor is arranged on a casing through a bracket, an output shaft of the motor is connected to one end of a driving crank, and 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] The fisheye joint B is connected to the pressure rod guide frame through the locking screw and the locking nut; the pressure rod guide frame is arranged on the pressure rod, the pressure rod moves up and down in the pressure rod bushing, and the middle pressure foot is fixed at the lower end of the pressure rod. The pressure rod guide frame guides and limits the radial rotation of the pressure rod;

[0052] A sensing plate is arranged on the driving crank; the sensor is fixed on the bracket; when the presser foot is raised to the highest point, the sensing plate is above the sensing area of ​​the sensor;

[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 middle presser foot, so that the middle presser foot is lifted; conversely, the motor rotates counterclockwise and the middle presser foot descends; the motor swings back and forth, and when the middle presser foot moves up and down at a certain amplitude, the middle 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 middle presser foot is lifted to the preset highest point; when the middle 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 given in part in the following description and in part will be obvious from the following description, or will be learned through 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 easily understood from the description of the embodiments in conjunction with the following 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 A 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 A flow chart 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. Pressure rod guide

[0072] 11. Pressure rod

[0073] 12. Pressure rod bushing

[0074] 13. Middle presser foot

[0075] 14. Casing

[0076] 15. Axis screw

[0077] 16. Locking nut

[0078] 17. Fisheye connector B

[0079] 18. Nut B. DETAILED DESCRIPTION

[0080] The specific implementation methods of the present application are further described in detail below in conjunction with the accompanying drawings. These implementation methods are only used to illustrate the present application, and are not intended to limit the present invention.

[0081] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0082] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0083] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

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

[0085] First, the motor 2 is fixed to the housing 14 through the bracket 1, and the driving crank 3 is installed on the output shaft of the motor 2. The other end of the driving crank 3 is connected to the fisheye joint A6 through the axial screw 15. The fisheye joint A6 is threadedly connected to the connecting rod 8 and locked by the nut A7. Both ends of the connecting rod 8 are threaded, and the other end is connected to the fisheye joint B17 and locked by the nut B18. The fisheye joint B17 is connected to the pressure rod guide frame 10 through the locking screw 9 and the locking nut 16. The pressure rod guide frame 10 is fixed on the pressure rod 11, and the pressure rod 11 moves up and down in the pressure rod bushing 12. The lower end of the pressure rod 11 is fixed with a middle presser foot 13. The pressure rod guide frame 10 guides and limits 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 bracket 1. When the presser foot is raised 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 this solution.

[0087] according to Figure 1 , when the motor 2 rotates clockwise, the driving crank 3 is driven to rotate clockwise around the motor 2 axis. The driving crank 3 then drives the fisheye joint A6 to lift, and transmits it to the connecting rod 8, the fisheye joint B17, the pressure rod guide frame 10, the pressure rod 11, and the middle presser foot 13 in sequence, so that the middle presser foot 13 is lifted. On the contrary, the motor 2 rotates counterclockwise, and the middle presser foot 13 drops. The motor 2 swings back and forth, and when the middle presser foot 13 moves up and down at a certain amplitude, it constitutes the follow-up of the middle presser foot 13. The lower limit height of the follow-up can be changed, and the amplitude of the follow-up, that is, the follow-up stroke, can also be changed. When sewing is finished, the middle presser foot 13 is lifted to the preset highest point. When the middle presser foot 13 is lifted to the highest point, the sensor 4 should be able to sense the induction plate 5.

[0088] The present application provides a control method and structure of a middle presser foot mechanism which has a simple structure, can change the stroke during movement, has a low motor load, and has simple parts and installation.

[0089] like Figure 3 , a method for controlling a middle presser mechanism of the present application, a control unit controls the rotation of a spindle motor, a middle presser motor and a feed motor according to a pattern to control the sewing stitch;

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

[0091] The spindle motor controls the thread picking and hook hooking, the presser motor controls the presser press, and the feed motor controls the X / Y axis movement for feeding. Since the three are controlled independently, the timing can be adjusted during the sewing process without waiting until the sewing machine stops. The sewing machine can automatically adjust according to the thickness and 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 middle presser foot mechanism includes: the first step, obtaining the sewing speed and the middle presser foot height in the pattern; the second step, determining the pressing angle range according to the fabric thickness and the sewing speed; the third step, determining the middle presser foot stroke according to the fabric thickness and the middle presser foot height; the fourth step, controlling the spindle motor and the middle presser foot motor according to the above information.

[0093] The first step is to obtain the sewing speed and the middle presser foot height in the pattern. The pattern parameter data should at least include parameters such as stitch length, sewing speed, middle presser foot height, thread tension parameters, and the above parameters can be set in sections. The sewing speed and middle presser foot height of the pattern are determined according to the material, single layer thickness, number of layers, etc. of the fabric. The middle presser foot height is the lower limit height of the middle presser foot follow-up. For example, when sewing a 3-layer denim plus velvet fabric, set the middle presser foot height to 2.5mm and the sewing speed to 3000rpm; when sewing a 10-layer denim plus velvet fabric, set the middle presser foot height to 7mm and the sewing speed to 1500rpm.

[0094] The pattern parameters may also include needle width, pattern type, pattern density, pattern length, pattern alignment, pattern direction, pattern repetition times, reverse pattern, elastic pattern, automatic pattern adjustment and other parameters;

[0095] The second step is to obtain a given pressing angle range according to the fabric thickness and sewing speed. The expected pressing angle range corresponding to different fabric thicknesses and sewing speeds needs to be preset in the program. Therefore, during execution, the given pressing angle range is obtained from the expected pressing angle range according to the fabric thickness and sewing speed.

[0096] When the motor drive mechanism moves, it takes a certain amount of time to complete the response after the control unit issues a command. Therefore, the pressing angle range is defined as a given pressing angle range.

[0097] Compared with the expected pressing angle range, the given pressing angle range corresponds to the spindle motor angle for which the control unit issues a corresponding instruction, and the expected pressing angle range corresponds to the expected spindle motor angle for pressing.

[0098] Therefore, the given pressing angle range includes the pressing process and the lifting process, which represents the spindle motor angle range from when the control unit issues a start pressing instruction to when the control unit issues a completion lifting instruction.

[0099] The expected material pressing angle range represents the expected spindle motor angle range from when the material pressing mechanism starts pressing down to when it completes lifting up.

[0100] The third step is to determine the stroke of the middle presser foot according to the fabric thickness and the middle presser foot height. The middle presser foot stroke corresponding to different fabric thicknesses and middle presser foot heights needs to be preset in the program. Therefore, during execution, the middle presser foot stroke is determined by the fabric thickness and the middle presser foot height.

[0101] The stroke of the middle presser foot refers to the difference between the highest point and the lowest point of the middle presser foot when it is following. Corresponding to the angle of the middle presser foot motor, that is, the motor angles of the lowest point and the highest point of the middle presser foot need to be determined according to the thickness of the fabric and the height of the middle presser foot. Because the motor has overshoot when it swings back and forth at high speed, the presser foot actually rises to the highest point once, which is just the beginning of the next downward pressure.

[0102] as follows Figure 4 As shown, according to Figure 4 The curve shown is the command for the given angle of the intermediate presser motor. The actual angle is not equal to the given motor angle. The actual highest angle is greater than the given highest angle, and the actual lowest angle is less than the given lowest angle. The spindle angles corresponding to the given lowest angle and the actual lowest angle are different.

[0103] Thus, you can set:

[0104] Angle A represents the spindle motor angle at which the control unit issues a start-press command;

[0105] Angle B represents the spindle motor angle at which the control unit issues the end-pressing command;

[0106] Angle C represents the spindle motor angle at which the control unit issues a start lift command;

[0107] Angle D, which indicates the spindle motor angle at which the control unit issues the command to end the lifting;

[0108] Angle E, represents the spindle motor angle when the intermediate presser foot actually reaches the highest point;

[0109] Angle F, which indicates the spindle motor angle when the intermediate presser foot actually reaches the lowest point;

[0110] Angle G, which indicates the spindle motor angle at which the presser foot is expected to reach the highest point;

[0111] Angle H, represents the spindle motor angle at which the presser foot is expected to reach the lowest point;

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

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

[0114] The advance angle K represents the spindle motor angle at which the presser foot is expected to reach the highest point and the spindle motor angle at which the control unit issues the command to end the lifting, that is, the advance angle K = angle G - angle D.

[0115] The advance angle L represents the spindle motor angle at which the presser foot is expected to reach 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.

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

[0117] The fourth step is to control the middle presser 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 synchronization, bottom dead center height and follow-up stroke of the middle presser foot in the slow-down sewing area. Take the pocket opening of the pocket machine as an example. The pocket opening is made of multiple layers of fabric folded and sewn. During the pressing process of the multi-layer fabric, the middle presser foot has a pressing effect on the fabric to make the fabric compact. In the process of the needle moving downward to pierce the fabric and then leaving the fabric to return to the highest point, the middle presser foot also completes the process of pressing down to contact the fabric and then pressing to the lowest point, and then lifting and leaving the fabric to the highest point. In this process, if the needle has penetrated the fabric and the middle presser foot has not yet pressed to the lowest point, if the feeding mechanism is still feeding at this time, it is easy to cause fabric displacement, skipped stitches and broken threads, needle bending and even needle breakage. At this time, the middle presser foot can be pressed down in advance, and a reasonable bottom dead center height and follow-up stroke can be set to press the fabric into place in advance, and after the feeding starts, the middle presser foot is higher than the fabric and there will be no dragging.

[0120] That is, during the sewing process, first, 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 over-thick area. If only the sewing speed set in the pattern is reduced, and the set middle presser foot height does not change, it cannot be determined that the fabric is sewn to an over-thick area.

[0121] Then, when it is judged to be too thick, the control program automatically advances angle A and angle B according to the preset control parameters 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 issues a start press command and the spindle motor angle at which the control unit issues an 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 set middle presser foot height, 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. The adjustment is performed according to the different middle presser foot heights and middle presser foot motor angles set 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 stitches; 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 the sewing speed; The control unit obtains a given middle presser foot stroke from an expected middle presser foot stroke according to the fabric thickness and the middle presser foot height; The middle presser foot height is the lower limit height of the middle presser foot following 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 when the control unit issues a start pressing command to when the control unit issues a completion lifting command; The expected pressing angle range is: the expected spindle motor angle range from when the pressing mechanism starts pressing down to when it completes lifting up; The target parameters of the pattern include the sewing speed and the height of the middle presser foot in the pattern.

2. A method for controlling a middle presser foot mechanism as claimed in claim 1, characterized in that: Loop execution to obtain The pattern parameters at least include the data of stitch length, sewing speed, middle presser foot height and thread tension.

3. A method for controlling a middle presser foot mechanism as claimed in claim 2, characterized in that: The pattern parameters also include one or a combination of data of 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 as claimed in claim 1, characterized in that: Preset different fabric thicknesses and sewing speeds, with corresponding expected pressing angle ranges; The given pressing angle range includes the pressing down process and the lifting process of the middle presser foot; Preset the expected presser foot stroke corresponding to different fabric thicknesses and presser foot heights; The command of the intermediate presser foot motor angle is given through the timing curve of the intermediate presser foot motor angle.

5. A method for controlling a middle presser foot mechanism as claimed in claim 4, characterized in that: The stroke of the middle presser foot is realized by the angle of the middle presser foot motor. The motor angles at the lowest and highest points of the middle presser foot are determined according to the thickness of the fabric and the height of the middle presser foot. set up: Angle A represents the spindle motor angle at which the control unit issues a 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 a start lift command; Angle D, which indicates the spindle motor angle at which the control unit issues the command to end the lifting; Angle E, represents the spindle motor angle when the intermediate presser foot actually reaches the highest point; Angle F, which 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 the highest point; Angle H, represents the spindle motor angle at which the presser foot is expected to reach the lowest point; Angle I, represents the angle of the middle presser foot motor at the highest point of the middle presser foot given by the control unit; Angle J, represents the angle of the middle presser foot motor at the lowest point of the middle presser foot given by the control unit; The advance angle K represents the spindle motor angle at which the presser foot is expected to reach the highest point and the spindle motor angle at which the control unit issues the command to end the lifting; that is, the advance angle K = angle G - angle D; The advance angle L represents the spindle motor angle at which the intermediate presser foot is expected to reach the lowest point and the spindle motor angle at which the control unit issues an end-pressing instruction; that is, the advance angle L = angle H - angle B.

6. A method for controlling a middle presser foot mechanism as claimed in claim 5, characterized in that: The spindle motor is used to control the thread picking of the needle material and the thread hooking of the rotary hook; Middle presser foot motor, used to control the middle presser foot to press materials; Feeding motor, used to control X / Y axis movement for feeding; The spindle motor, presser 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 middle presser motor and the feeding motor, so that the middle presser foot completes the corresponding action; Input parameters including fabric thickness, number of layers, etc. are automatically adjusted during the sewing process.

7. A method for controlling a middle presser foot mechanism as claimed in claim 5, characterized in that: 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 height of the middle presser foot 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 middle presser foot does not change, it cannot be determined that the sewing has reached an over-thick area; When it is judged to be too thick, the control program automatically advances Angle A and Angle B according to the preset control parameters 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 made.

8. A method for controlling a middle presser foot mechanism as claimed in claim 7, characterized in that: According to the set height of the middle presser foot, adjust angle I and angle J, and at the same time increase the difference between angle J and angle I; that is, increase the height of the middle presser foot and increase the stroke of the middle presser foot.

9. A method for controlling a middle presser foot mechanism as claimed in claim 8, characterized in that: Adjust angle I and angle J: Execute according to the different middle presser foot heights and middle presser foot motor angles set in advance in the control program.

10. A middle presser foot mechanism, using a middle presser foot mechanism control method as described in any one of claims 1 to 9, characterized in that: The motor (2) is arranged on the housing (14) through a bracket (1); the output shaft of the motor (2) is connected to one end of a driving crank (3); the other end of the driving crank (3) is connected to a fisheye joint A (6) through an axial screw (15); the fisheye joint A (6) is threadedly connected to one end of a connecting rod (8) and is locked by a nut A (7); the other end of the connecting rod (8) is threadedly connected to a fisheye joint B (17) and is locked by a 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 a middle pressure foot (13) is fixed to the lower end of the pressure rod (11); 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) then drives the fisheye joint A (6) to rise, and transmits the information to the connecting rod (8), the fisheye joint B (17), the pressure rod guide frame (10), the pressure rod (11), and the middle presser foot (13) in sequence, so that the middle presser foot (13) is raised; on the contrary, when the motor (2) rotates counterclockwise, the middle presser foot (13) is lowered; when the motor (2) swings back and forth, when the middle presser foot (13) moves up and down at a certain amplitude, the middle presser foot (13) is followed; 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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