Transmission structure for pressure control of three-roller machine and control method

Abstract

The invention discloses a transmission structure for pressure control of a three-roller machine and a control method. The two ends of a middle roller are arranged on a machine body, a front roller is rotationally arranged on a front roller adjusting frame through a front roller center shaft, the front roller adjusting frame is rotationally arranged on the machine body through a rotating fulcrum, and a rear roller is rotationally arranged on a rear roller adjusting frame through a rear roller center shaft; the rear roller adjusting frame is rotationally arranged on the machine body through a rotating fulcrum; servo motors are arranged at the lower end of the front roller adjusting frame and the lower end of the rear roller adjusting frame correspondingly and connected with the cams correspondingly, the pressure collecting mechanism is used for allowing the cams to abut against and collecting the pressure of the contact face, and the servo motors are used for driving the cams to rotate and driving the front roller or the rear roller to move close to or away from the middle roller. The servo motor is used for driving the cam to rotate and is matched with the pressure collecting mechanism to extrude the cam, so that the front roller or the rear roller is correspondingly driven to move, the gap between the front roller or the rear roller and the middle roller is controlled, the grinding efficiency is improved, and discharging is more stable.

Description

Technical Field

[0001] The invention relates to the field of grinding structure and control technology, and in particular to a transmission structure and a control method for pressure control of a three-roller mill. Background Art

[0002] Three-roller mill is widely used in wet grinding of raw materials in chemical industries such as paint, ink, ink, coating, dye, plastic, rubber, lead, leather, medicine, food, cosmetics and insulating materials. It has multiple functions such as crushing, dispersing, emulsifying homogenization and color matching. It can make the raw materials highly evenly mixed and recycle waste materials. Three-roller mill is suitable for grinding and dispersing products with high viscosity and fine particle size requirements. It has good grinding performance, stable quality, convenient operation and easy color change. Three-roller mill has three rollers installed on an iron frame, with the center in a straight line, which can be installed horizontally or slightly tilted. The three-roller mill achieves the grinding effect by squeezing the surfaces of three horizontal rollers against each other and rubbing at different speeds. The steel roller can be hollow and cooled by water. The material is added between the middle roller and the rear roller. Among them, the rotation direction of the three rollers can be different, and the speed can be increased from back to front in sequence, which can produce a good grinding effect.

[0003] In daily grinding machine work, it is very important to accurately control the pressure between the rollers. If the pressure on both sides of the roller is different, the pigment will be ground unevenly, with one side thicker and the other thinner, which will greatly affect the grinding quality and grinding efficiency. According to statistics, in the field of domestic grinding machines, many manufacturers' grinding machine transmission structure design is unreasonable, resulting in the pressure between each roller of the three-roller grinding machine cannot be well controlled, making the quality of the material ground each time poor, so repeated grinding is required, which not only wastes a lot of time, but also wastes manpower and material resources.

[0004] At present, there is a lack of grinders with high grinding efficiency on the market. The gap between the front, middle and rear rollers of many grinders is adjusted by hand. This control method is inefficient and there is no way to accurately control the pressure, so it is impossible to grind materials accurately and efficiently. There are also many three-roller grinders using pressure control mode on the market, but most of them control the pressure control motor independently, so that the pressure on both sides of the front and rear rollers is controlled by the motors on both sides separately. The synchronization between the two motors cannot be guaranteed by the separate control of the two motors. When one of the motors is disturbed, the other motor cannot respond quickly; single motor control cannot resist load disturbances well.

[0005] Therefore, there is an urgent need for a transmission structure and a control method for pressure control of a three-roll mill to solve the problem of poor grinding efficiency. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a transmission structure and a control method for pressure control of a three-roll mill to solve the problem of poor grinding efficiency.

[0007] To achieve the above object, the present invention adopts the following technical solutions:

[0008] A transmission structure for pressure control of a three-roller mill, characterized in that it includes a machine body, a front roller adjustment frame, a rear roller adjustment frame, a front roller, a middle roller, a rear roller, a cam driving mechanism and a pressure collection mechanism, wherein the cam driving mechanism includes a cam and a servo motor, the two ends of the middle roller are arranged on the machine body, the front roller is rotatably arranged on the front roller adjustment frame through the center axis of the front roller, the front roller adjustment frame is rotatably arranged on the machine body in front of the middle roller through a rotating fulcrum, and the center axis of the front roller is staggered with the rotating fulcrum on the front roller adjustment frame, and the rear roller is rotatably arranged through the center axis of the rear roller The shaft is rotatably arranged on the rear roller adjustment frame, and the rear roller adjustment frame is rotatably arranged on the machine body at the rear side of the middle roller through a rotating fulcrum, and the central axis of the rear roller is staggered with the rotating fulcrum on the rear roller adjustment frame; the lower ends of the front roller adjustment frame and the rear roller adjustment frame are respectively provided with servo motors, and the output ends of the servo motors are respectively connected to the middle of a cam, and the pressure collection mechanism is fitted on the side of the cam for the cam to resist and collect the pressure of the contact surface, and the servo motor is used to drive the cam to rotate and drive the front roller or the rear roller to move closer to or away from the middle roller.

[0009] To optimize the above technical solutions, the specific measures taken also include:

[0010] Furthermore, the front roller adjustment frame and the rear roller adjustment frame both include a rotating link arm, the two ends of the front roller are rotatably set on the rotating link arm through the front roller center axis, the rotating link arms at the two ends of the front roller are rotatably set on the machine body on the front side of the middle roller through a rotating fulcrum, and the rotating fulcrum on the front roller adjustment frame is located above and misaligned with the front roller center axis; the two ends of the rear roller are rotatably set on the rotating link arm through the rear roller center axis, the rotating link arms at the two ends of the rear roller are rotatably set on the machine body on the rear side of the middle roller through a rotating fulcrum, and the rotating fulcrum on the rear roller adjustment frame is located above and misaligned with the rear roller center axis.

[0011] Furthermore, the pressure collection mechanism includes a pressure sensing mechanism and a bolt B. The pressure sensing mechanism is mounted on the machine body via the bolt B. The collection end of the pressure sensing mechanism is always in contact with the side of the cam.

[0012] Furthermore, the pressure sensing mechanism includes a metal block, a contact arc surface, a stress strain gauge and a stress strain acquisition circuit. The upper end of the metal block is provided with a contact arc surface that always fits and contacts the side of the cam. The metal block is symmetrically provided with a groove on both sides close to and away from the cam below the contact arc surface. A stress strain gauge for sensing deformation is provided in the groove. The stress strain acquisition circuit is connected to the stress strain gauge for collecting and transmitting signals.

[0013] Furthermore, the pressure collection mechanism also includes a bolt A, and the pressure sensing mechanism is installed on the body through a bolt B and a bolt A that is misaligned with the bolt B.

[0014] Furthermore, a cam driving mechanism is provided at the lower end of each of the two sides of the front roller adjusting frame, and a cam driving mechanism is provided at the lower end of each of the two sides of the rear roller adjusting frame, and each of the cam driving mechanisms is respectively provided with a corresponding pressure collection mechanism.

[0015] Furthermore, the cam is a rotationally linearized cam designed according to an involute.

[0016] Furthermore, it also includes a rotating mechanism, which is respectively connected to and drives the front roller and the rear roller to rotate.

[0017] Furthermore, a control method is characterized in that it also includes a constant pressure decoupling control system and a material output detection system. The constant pressure decoupling control system sends instructions to the servo motor of the corresponding cam drive mechanism through the CAN bus, and controls the rotation of the cam thereon through the servo motor. The cam correspondingly drives the left or right side of the front roller adjustment frame as a transmission mechanism, or the left or right side of the rear roller adjustment frame to move, so as to adjust the distance between the front roller or the rear roller and the middle roller on both sides; the material output detection system is used to detect whether the material output is qualified. If the detection is qualified, the material is directly discharged. If the detection is unqualified, the constant pressure decoupling control system is fed back according to the detection result to adjust the speed of the servo motor on both sides of the front roller or the rear roller, thereby controlling the distance between the front roller or the rear roller and the middle roller on both sides until the discharge is qualified.

[0018] Furthermore, the constant pressure decoupling control system includes a touch screen system for monitoring and controlling the servo motor, a pressure ring sliding mode controller and a decoupling controller, and the lower ends of both sides of the front roller adjustment frame and the rear roller adjustment frame are respectively provided with a cam driving mechanism and a pressure collection mechanism, and the touch screen system sends instructions to the servo motor of the corresponding cam driving mechanism through the CAN bus, and controls the rotation of the cam thereon through the servo motor;

[0019] The actual positions of the two servo motors on both sides of the front roller adjustment frame are collected by using the touch screen system. The actual position of each servo motor is subtracted from the input position to obtain the tracking error. The actual position of one servo motor is multiplied by the disturbance coefficient as the load disturbance of the other servo motor. The actual position is added to the actual position of the original servo motor and then multiplied by the stress-strain pressure coefficient to obtain the actual pressure value. The actual pressure values ​​of the two servo motors are subtracted to obtain the synchronization error.

[0020] Among them, the two servo motors are divided into servo motor A and servo motor B. For servo motor A, the input is the pressure set value. The pressure is converted into a position value through the calibrated stress strain coefficient and input into servo motor A. The actual position of servo motor B is multiplied by the disturbance coefficient as the load disturbance of servo motor A. The actual position of servo motor A plus the load disturbance are fed back to the input end, and the position tracking error of servo motor A is obtained by subtracting the input position. The actual position of servo motor A and the load disturbance are added and multiplied by the stress strain gain to obtain the actual pressure value of servo motor A. The difference between it and the actual pressure value of servo motor B is used as the input of the decoupling controller. The decoupling controller will feed back the changed pressure difference on both sides to the pressure ring sliding mode controller through the decoupling coefficient to adjust the position of the servo motors on both sides, so that the pressure on both sides of the front roller tends to be stable after a short period of fluctuation. The same control is adopted for the rear roller.

[0021] The beneficial effects of the present invention are:

[0022] The present invention uses a servo motor to drive the cam to rotate, and cooperates with the pressure collection mechanism to squeeze the cam, thereby correspondingly driving the movement of the front roller or the rear roller. The cam rotates to perform linear motion, and can complete various complex movements, including linear motion, swinging, constant speed motion and non-constant speed motion, so the servo motor can well control the pressure between the front roller or the rear roller and the middle roller through the cam. For example, when the cam rotates to squeeze the pressure collection mechanism, the front roller adjustment frame that controls the movement of the front roller is driven by the cam to swing around the rotating fulcrum thereon, thereby driving the front roller to move, thereby changing the gap size between the front roller and the middle roller. The structure in this scheme drives the cam to perform linear motion through the servo motor, thereby accurately controlling the pressure of the front roller and the middle roller, so that the error of the hand-cranked pressure control can be reduced, which is convenient for the grinder to adjust different pressures for different grinding materials, improve the grinding efficiency, and control the different pressures between the rollers for different materials as needed, so that the three-roll grinder has a higher utilization rate of raw materials and more stable discharge.

[0023] The structure of the present invention can be changed according to the needs of the grinding material by controlling the pressure between the front roller and the middle roller, and between the rear roller and the middle roller. It has the advantages of convenient adjustment of the pressure between the front roller, the middle roller and the rear roller, etc., and solves the problem that the size and thickness of the ground material cannot be changed due to the inability to properly and reasonably adjust the pressure between the front roller, the middle roller and the rear roller, and there is no way to adjust the pressure according to different grinding materials, which greatly reduces the practicality of the three-roll grinder.

[0024] The present invention controls the rotation of the cam by positionally controlling the servo motor through a control system, and squeezes the pressure sensing mechanism around it, and changes the pressure between one side of the front roller and the middle roller by rotating the connecting rod arm and other structures, collects and detects the ground materials, and gives corresponding feedback to the control system according to the results of the material detection, and directly discharges the qualified materials, and gives corresponding instructions to the corresponding servo motors according to the judgment of the control system for the unqualified materials, and adjusts the rotation of the servo motor to adjust the pressure between the two sides of the front roller and the middle roller; the pressure at both ends of the rollers is collected and differentiated, and the pressure difference is input into the two servo motors through the decoupling coefficient of the decoupling control algorithm, and becomes a part of the control instructions of the two servo motors, and is dynamically compensated by the sliding mode controller, so that the pressure between the rollers can be controlled to be maintained near the set value, thereby improving the stability of the control, and at the same time meeting the high-precision requirements for the control, and improving the grinding quality and efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A structural side view of a transmission structure for pressure control of a three-roller mill proposed by the present invention;

[0026] Figure 2 A schematic diagram of a cam structure of a transmission structure for pressure control of a three-roller mill proposed by the present invention;

[0027] Figure 3 A schematic diagram of the structure of a pressure sensing mechanism of a transmission structure for pressure control of a three-roller mill proposed by the present invention;

[0028] Figure 4 It is a flow chart of a control method of a transmission structure for pressure control of a three-roller mill proposed by the present invention;

[0029] Figure 5 A diagram showing the rotation angle relationship of a servo motor of a transmission structure for pressure control of a three-roller mill proposed by the present invention;

[0030] Figure 6 A diagram showing the relationship between the front roller movement distance of a transmission structure for pressure control of a three-roller mill proposed by the present invention;

[0031] Figure 7This is a structural block diagram of a decoupling control system of a transmission structure for pressure control of a three-roller mill proposed by the present invention.

[0032] Figure markings: 1-rotating link arm, 2-pressure sensing mechanism, 3-bolt B, 4-bolt A, 5-cam, 6-servo motor, 7-front roller center axis, 8-front roller, 9-rotation fulcrum, 10-middle roller, 11-rear roller, 12-rear roller center axis, 13-machine body, 14-stress strain gauge, 15-contact arc surface, 16-stress strain acquisition circuit. DETAILED DESCRIPTION

[0033] The present invention will now be described in further detail with reference to the accompanying drawings.

[0034] As attached Figure 1 As shown, a transmission structure for pressure control of a three-roller mill according to an embodiment of the present invention comprises a machine body 13, a front roller adjustment frame, a rear roller adjustment frame, a front roller 8, a middle roller 10, a rear roller 11, a cam driving mechanism and a pressure collection mechanism, wherein the cam driving mechanism comprises a cam 5 and a servo motor 6, both ends of the middle roller 10 are arranged on the machine body 13, the front roller 8 is rotatably arranged on the front roller adjustment frame through the front roller center axis 7, the front roller adjustment frame is rotatably arranged on the machine body 13 in front of the middle roller 10 through a rotating fulcrum 9, and the front roller center axis 7 is staggered with the rotating fulcrum 9 on the front roller adjustment frame, and the rear roller 11 is rotatably arranged through the rear roller center axis 12 The rear roller adjustment frame is rotatably arranged on the rear roller adjustment frame, and the rear roller adjustment frame is rotatably arranged on the body 13 on the rear side of the middle roller 10 through the rotating fulcrum 9, and the rear roller center axis 12 is staggered with the rotating fulcrum 9 on the rear roller adjustment frame; the lower ends of the front roller adjustment frame and the rear roller adjustment frame are respectively provided with servo motors 6, and the output ends of the servo motors 6 are respectively connected to the middle of a cam 5, and the pressure collection mechanism is fitted on the side of the cam 5 for the cam 5 to resist and collect the pressure of the contact surface, and the servo motor 6 is used to drive the cam 5 to rotate, and drive the front roller 8 or the rear roller 11 to move closer to or away from the middle roller 10 around their respective rotating fulcrums 9.

[0035] When the present invention is in use, the servo motor 6 is used to drive the cam 5 to rotate, and the pressure collection mechanism is used to squeeze the cam 5, thereby correspondingly driving the movement of the front roller 8 or the rear roller 11. The cam 5 rotates to make linear motion, and various complex motions can be completed, including linear motion, swinging, constant speed motion and non-constant speed motion. Therefore, the servo motor 6 can well control the pressure between the front roller 8 or the rear roller 11 and the middle roller 10 through the cam 5. For example, when the cam 5 rotates to squeeze the pressure collection mechanism, the front roller adjustment frame that controls the movement of the front roller 8 is driven by the cam 5 to swing around the rotating fulcrum 9 thereon, thereby driving the front roller 8 to move, thereby changing the pressure between the front roller 8 and the middle roller 10. The structure in this scheme drives the cam 5 to make linear motion through the servo motor 6, thereby accurately controlling the pressure of the front roller 8 and the middle roller 10, so that the error of the hand-cranked pressure control can be reduced, which is convenient for the grinder to adjust different pressures for different grinding materials, improve the grinding efficiency, and control the different pressures between the rollers for different materials as needed, so that the three-roll grinder has a higher utilization rate of raw materials and more stable discharge.

[0036] The structure of the present invention can be changed according to the needs of the grinding material by controlling the pressure between the front roller 8 and the middle roller 10, as well as the pressure between the rear roller 11 and the middle roller 10. It has the advantages of convenient adjustment of the pressure between the front roller 8, the middle roller 10 and the rear roller 11, etc., and solves the problem that the size and thickness of the ground material cannot be changed due to the inability to properly and reasonably adjust the pressure between the front roller 8, the middle roller 10 and the rear roller 11, and there is no way to adjust the pressure according to different grinding materials, which greatly reduces the practicality of the three-roll grinder.

[0037] Specifically, one side of the cam 5 is against the pressure collection mechanism, and the servo motor 6 controls the rotation of the cam 5 by rotating the motor shaft. The rotation of the cam 5 is a linear motion. The linear motion of the cam 5 and the pressure collection mechanism squeeze each other, so that the cam 5 moves to the other side of the squeezing, driving the corresponding front roller adjustment frame to swing around the rotating fulcrum 9 thereon. During the swinging process, the front roller 8 on the front roller adjustment frame will move accordingly. Because the position of the middle roller 10 is fixed, the distance between the front roller 8 and the middle roller 10 can be changed to control the pressure. The pressure between the front roller 8 and the middle roller 10 can be controlled by controlling the distance of the linear motion of the cam 5 according to the rotation angle of the servo motor 6. In this solution, the pressure collection mechanism is used for zero position setting and is connected to the cam.

[0038] In another specific embodiment based on the above, the front roller adjustment frame and the rear roller adjustment frame both include a rotating link arm 1, the two ends of the front roller 8 are rotatably set on the rotating link arm 1 through the front roller center axis 7, the rotating link arms 1 at the two ends of the front roller 8 are rotatably set on the body 13 on the front side of the middle roller 10 through the rotating fulcrum 9, and the rotating fulcrum 9 on the front roller adjustment frame is located above and misaligned with the front roller center axis 7; the two ends of the rear roller 11 are rotatably set on the rotating link arm 1 through the rear roller center axis 12, the rotating link arms 1 at the two ends of the rear roller 11 are rotatably set on the body 13 on the rear side of the middle roller 10 through the rotating fulcrum 9, and the rotating fulcrum 9 on the rear roller adjustment frame is located above and misaligned with the rear roller center axis 12.

[0039] In this embodiment, the servo motor 6 can be placed on the inner side of the body 13, with one side of the rotating shaft of the servo motor 6 facing outward, the cam 5 is fixed on the rotating shaft of the servo motor 6, and one side of the motor rotating shaft of the servo motor 6 is fixed on the rotating link arm 1 with three screws.

[0040] In another specific embodiment based on the above, the pressure collection mechanism includes a pressure sensing mechanism 2 and a bolt B3, the pressure sensing mechanism 2 is mounted on the machine body 13 by the bolt B3, and the collection end of the pressure sensing mechanism 2 is always in contact with the side of the cam 5. In this embodiment, the collection end of the pressure sensing mechanism 2 can be set to initially be in contact with the side with the smallest rotation distance from the cam 5.

[0041] As attached Figure 3 As shown, in a further embodiment, the pressure sensing mechanism 2 includes a metal block, a contact arc surface 15, a stress strain gauge 14 and a stress strain acquisition circuit 16. The upper end of the metal block is provided with a contact arc surface 15 that is always in contact with the side of the cam 5. The metal block is symmetrically provided with a groove on both sides close to and away from the cam 5 below the contact arc surface 15. The groove is provided with a stress strain gauge 14 for sensing deformation. The stress strain acquisition circuit 16 is connected to the stress strain gauge 14 for collecting and transmitting signals.

[0042] When in use, for example, the pressure on both sides of the front roller 8 is transmitted downward to the cam 5 through the rotating connecting rod arm 1 fixed at the top. The cam 5 transmits the pressure to the stress strain gauge 14 through the setting of the pressure sensing mechanism 2. The stress strain gauge 14 is deformed by the pressure, and stress and strain are generated inside. This stress and strain is a direct response of the sensitive element to the external pressure. The stress and strain acquisition circuit 16 converts this stress and strain into a corresponding electrical signal by using the piezoresistive effect, and transmits the electrical signal to the signal conditioning circuit. The signal conditioning circuit amplifies, filters and linearizes the received electrical signal to improve the stability and accuracy of the signal. It usually includes modules such as amplifiers, filters, and ADC analog-to-digital converters. The amplifier The device can amplify the weak signal output by the sensor to a range suitable for subsequent processing, the filter can remove noise and interference signals, and convert the processed analog signal into a digital signal through the ADC102 analog-to-digital converter to make the signal into a processable form, and then output the processed digital signal to one end of the controller through the output circuit. The controller makes corresponding processing based on the obtained digital signal. The output circuit is used to convert the signal-conditioned electrical signal into a readable or processable form. According to specific application requirements, the output can be an analog signal such as voltage or current or a digital signal such as a serial communication interface. The output circuit can also include a calibration circuit for calibrating the output of the sensor to improve the accuracy of the measurement.

[0043] Among them, the stress strain gauge 14 is based on the interaction between the internal stress and the deformation generated when the object is subjected to external force. Stress is a physical quantity that describes the additional internal force per unit area inside the object. It can be caused by external forces such as stretching, compression, shearing or bending. Strain describes the change in shape or size of an object under the action of external force. The relationship between stress and strain is usually described by Hooke's law. Within the elastic range, that is, when the stress on the object does not exceed its elastic limit, the relationship between stress and strain is linear. The pressure at both ends of the front roller 8 and the middle roller 10 is converted to the stress strain gauge 14, and the pressure data can be obtained through stress strain calculation.

[0044] In a further embodiment, the pressure collection mechanism further includes a bolt A4, and the pressure sensing mechanism 2 is installed on the machine body 13 through the bolt B3 and the bolt A4 offset from the bolt B3. After the bolt B3 limits the pressure sensing mechanism 2, fine adjustment can be made as needed, and then the offset bolt A4 can be used to completely tighten it.

[0045] In another specific embodiment based on the above, a cam driving mechanism is provided at the lower end of each side of the front roller 8 on the front roller adjustment frame, and a cam driving mechanism is provided at the lower end of each side of the rear roller 11 on the rear roller adjustment frame, and each cam driving mechanism is respectively provided with a corresponding pressure collection mechanism.

[0046] As attached Figure 2As shown, in another specific embodiment based on the above, the cam 5 is a rotational linearized cam designed according to an involute.

[0047] In another specific embodiment based on the above, a rotating mechanism is further included, and the rotating mechanism is respectively connected to and drives the front roller 8 and the rear roller 11 to rotate. In this solution, the middle roller 10 is provided with a middle roller central axis 10 as required, and the rotating mechanism can be connected to the middle roller central axis 10 as required and drive the middle roller 10 to rotate. In this solution, the front roller central axis 7 and the rear roller central axis 12 can also be connected to the front roller 8 or the rear roller 11 through an asynchronous motor, respectively, to control the rotation of the front roller 8 or the rear roller 11, or to drive with a gear for grinding materials.

[0048] As attached Figure 4 As shown, a transmission structure and control method for pressure control of a three-roller mill also include a constant pressure decoupling control system and a material output detection system. The constant pressure decoupling control system sends instructions to the servo motor 6 of the corresponding cam drive mechanism through the CAN bus, and controls the rotation of the cam 5 thereon through the servo motor 6. The cam 5 correspondingly drives the left or right side of the front roller adjustment frame as a transmission mechanism, or the left or right side of the rear roller adjustment frame to move, so as to adjust the distance between the front roller 8 or the rear roller 11 and the middle roller 10 on both sides; the material output detection system is used to detect whether the material output is qualified. If the detection is qualified, the material is directly discharged. If the detection is unqualified, the constant pressure decoupling control system is fed back according to the detection result to adjust the speed of the servo motor 6 on both sides of the front roller 8 or the rear roller 11, thereby controlling the distance between the front roller 8 or the rear roller 11 and the middle roller 10 on both sides until the discharge is qualified.

[0049] As attached Figure 7 As shown, further, the constant pressure decoupling control system includes a touch screen system for monitoring and controlling the servo motor 6, a pressure ring sliding mode controller and a decoupling controller, and the lower ends of both sides of the front roller adjustment frame and the rear roller adjustment frame are respectively provided with a cam driving mechanism and a pressure collection mechanism, and the touch screen system sends instructions to the servo motor 6 of the corresponding cam driving mechanism through the CAN bus, and controls the rotation of the cam 5 thereon through the servo motor 6;

[0050] The actual positions of the two servo motors 6 on both sides of the front roller adjustment frame are collected by using the touch screen system, and the actual position of each servo motor 6 is subtracted from the input position to obtain the tracking error. The actual position of one of the servo motors 6 is multiplied by the disturbance coefficient as the load disturbance of the other servo motor 6, and the actual position is added to the actual position of the original servo motor 6 and then multiplied by the stress-strain pressure coefficient to obtain the actual pressure value. The actual pressure values ​​of the two servo motors 6 are subtracted to obtain the synchronization error.

[0051] Among them, the two servo motors 6 are divided into servo motor A and servo motor B. For servo motor A, the input is the pressure setting value. The pressure is converted into a position value through the calibrated stress strain coefficient and input into servo motor A. The actual position of servo motor B is multiplied by the disturbance coefficient as the load disturbance of servo motor A. The actual position of servo motor A plus the load disturbance are fed back to the input end, and the position tracking error of servo motor A is obtained by subtracting the input position. The actual position of servo motor A and the load disturbance are added and multiplied by the stress strain gain to obtain the actual pressure value of servo motor A. The difference between the actual pressure value of servo motor A and the actual pressure value of servo motor B is used as the input of the decoupling controller. The decoupling controller will feed back the changed pressure difference on both sides to the pressure ring sliding mode controller through the decoupling coefficient to adjust the position of the servo motors 6 on both sides, so that the pressure on both sides of the front roller 8 tends to be stable after a short period of fluctuation. The rear roller 11 adopts the same control.

[0052] Among them, the pressure loop sliding mode control and decoupling control include sliding mode control of pressure and decoupling control of the difference of the actual pressure values ​​of the two servo motors 6. For the sliding mode control of the pressure loop, the main steps are sliding surface design, control law design and controller implementation. The main step of decoupling control of the pressure difference is to adjust the decoupling coefficient of the pressure of the two servo motors.

[0053] During use, the pressure on both sides of the front roller 8 is set according to the grinding requirements of the material and a constant value is set. When grinding starts, the pressure on both sides of the front roller 8 changes due to the addition of the material. The change in pressure causes one side of the front roller 8 to shift. Since the other side is coupled to this side, the other side will also shift based on the coupling factor due to the displacement of this side, resulting in changes in the pressure on both sides of the front roller 8. At this time, the decoupling controller will feed back the changed pressure difference on both sides to the pressure ring sliding mode controller through the decoupling coefficient, thereby adjusting the position of the servo motors 6 on both sides, so that the pressure on both sides of the front roller 8 tends to stabilize after a short period of fluctuation, will not affect the grinding of the material, and ensure the grinding accuracy.

[0054] When the present invention is used:

[0055] To set the zero position:

[0056] First, fix the lower end of the pressure sensor mechanism 2 with bolt A4, hold the upper end of the pressure sensor mechanism 2 with your hand, and control the servo motor 6 to rotate the cam 5 at the same time. When the top of the cam 5 is against the pressure sensor mechanism 2, fix the upper end of the pressure sensor mechanism 2 with bolt B3 to complete the zero position setting. The encoder in the servo motor 6 remembers the position of the zero point after the zero position setting, which is convenient for the return to zero operation later.

[0057] Specific operation process:

[0058] Compared with manually controlling the distance between the front roller 8 and the middle roller 10, for pressure control, this solution controls the distance between the front roller 8 and the middle roller 10 and between the middle roller 10 and the rear roller 11 by controlling the rotation of the servo motor 6, so that the control of pressure is more precise; for pressure control, by inputting pressure to the servo motor 6, the position of the servo motor 6 is controlled by sliding mode control in the pressure loop, and for the mutual influence of the pressures of the two servo motors 6, decoupling control is used to increase the pressure difference of the two servo motors 6 and the multiplication of the adjusted decoupling coefficient to the pressure loop input of the two servo motors 6, so that each servo motor 6 can decouple the pressure load disturbance of the other servo motor 6, thereby maintaining the stability of pressure control and improving the control accuracy.

[0059] For the pressure controller, a sliding mode controller is used to design the pressure controller. The design of the sliding mode structure controller u is as follows:

[0060] u=u eq +u sw

[0061] Where: u eq It is equivalent control, which can realize the tracking of the controller system state, that is, keep the system state on the sliding surface; u sw It is a switching control that makes the system state approach the sliding surface and weakens the system's chattering.

[0062] Design the sliding mode switching function s as:

[0063] s=c1e1+c2e2+e3

[0064] Where: c1 and c2 are the desired poles, which determine the dynamic quality of the sliding mode.

[0065] The differential equation of sliding mode motion is:

[0066]

[0067] Where: e1, e2 and e3 are system errors, ω h is the natural frequency of the system, ξ h is the damping ratio of the system, K h is the gain of the system output to the input.

[0068] Using the exponential reaching law, in the equivalent control part, the derivative of s = c1e1 + c2e2 + e3 is obtained:

[0069]

[0070] according to The equivalent control can be obtained:

[0071]

[0072] The switch control part is:

[0073] u sw =-εsgn(s)-ks

[0074] Where: sgn(s) is the exponential convergence rate,

[0075] In summary, the design of the sliding mode controller is:

[0076]

[0077] Where: ε is the width of the sliding surface, k is the parameter of the exponential approach rate.

[0078] For example, the pressure inputted by the controller system enters the position controller after being adjusted by the sliding mode controller. The position controller adopts simple proportional control for control. After passing through the position controller, since the initial setting positions of the two servo motors 6 are different, when the servo motors 6 perform position control, the two ends of the controlled front roller 8 will produce deviations due to the different initial positions of the servo motors 6. The position change of the servo motor 6 on one side of the front roller 8 will cause the roller on that side to shift, thereby driving the other side of the roller to shift, thus coupling the two sides of the roller to each other, and coupling the position control of the two servo motors 6 to each other. As a result, the pressure on both sides of the roller is also coupled to each other.

[0079] Regarding the pressure coupling between the two servo motors 6, it is simplified to the position coupling between the two servo motors 6, hereinafter referred to as motor 1 and motor 4. The position of motor 1 at this moment is subtracted from the position of motor 1 at the previous moment, and the position difference is multiplied by the coupling coefficient and added to the position output by motor 2 as the coupling of motor 1 to motor 2; similarly, the position of motor 2 at this moment is subtracted from the position of motor 2 at the previous moment, and the position difference is multiplied by the coupling coefficient and added to the position output by motor 1 as the coupling of motor 2 to motor 1.

[0080] In view of the situation where the pressures on both sides of the roller are coupled to each other due to the mutual coupling of the motor positions, a decoupling controller is used to solve this problem. The difference in the output pressures of the coupled motor 1 and motor 2 is introduced into the decoupling controller. After multiplication by the decoupling coefficient of the decoupling controller, the output result is fed back to the pressure sliding mode controller as part of the input of the pressure sliding mode controller, so as to adjust the positions of the two motors, change the pressures of the two motors, and achieve decoupling control of the pressure.

[0081] When the servo motor 6 is in the position control mode, the controller adjusts the output of the motor to make it reach the predetermined position. The servo motor 6 controls the rotation of the motor shaft to control the rotation of the cam 5. The cam 5 performs linear motion and squeezes the pressure sensing mechanism 2 fixed after the zero position is set on its left side, thereby moving to the right. The movement of the cam to the right drives the pressure sensing mechanism 2 fixed on its outer side to move, thereby changing the distance between the front roller 8 and the middle roller 10.

[0082] The servo motor 6 controls the rotation of the cam 5 connected to the motor shaft by controlling the rotation of its motor shaft. The rotation of the cam 5 squeezes the pressure sensing mechanism 2 on the left side thereof for zero position setting and squeezing the cam 5, thereby controlling the movement of the front roller 8.

[0083] The control system, i.e., the touch screen used to monitor and control the servo motor, controls the rotation of motor 1 and motor 2 through the CAN bus. The two motors control the rotation of cams 5 on both sides through their respective motor shafts. Cams 5 control the movement of the left and right sides of the front roller respectively, thereby controlling the gap on both sides of the front roller 8. The front roller 8 outputs the material, and determines whether the material is qualified through material detection. Qualified materials are directly discharged, and unqualified materials are determined by observing their uniformity to determine which side of the front roller needs to adjust the pressure, thereby feeding back to the control system. The control system adjusts the speed of the servo motors on both sides according to the feedback data, thereby controlling the gap so that the material output meets the requirements.

[0084] On a plane, when a moving straight line (generating line) rolls along a fixed circle (base circle), the trajectory of any point on this straight line is called an involute of this base circle. Based on the principle of involute, the servo motor 6 controls the rotation angle of the motor shaft and the rotation angle of the cam 5 linear motion to control the moving distance of the front roller 8. The rotation angle of the servo motor 6 motor shaft is proportional to the moving distance of the front roller 8. Figure 5 As shown:

[0085]

[0086] Where: is the rolling angle, r is the radius of the circle, X k is the horizontal coordinate of point k, Y k is the ordinate of point k.

[0087] As attached Figure 6 As shown, CD is the distance moved by the front roller 8, and AB is the distance mapped from a point on the cam 5 to the two-dimensional coordinate system. Therefore, according to the similarity between triangle OCD and triangle OAB, the distance CD moved by the front roller 8 can be calculated.

[0088]

[0089] Where: d is the length of CD, l1 is the length of AO, and l2 is the length of CO.

[0090] That is, the distance that the front roller 8 moves is calculated to be Thus, the relationship between the distance moved by the front roller 8 and the angle of rotation of the servo motor 6 is obtained.

[0091] The method of the present invention can improve control stability and synchronization performance: when one of the motors is disturbed, the other motor can respond quickly to maintain synchronization between the two; enhance system robustness: the dual-motor system can better resist load disturbances and improve system stability and robustness. This decoupling control method enables one motor to quickly adjust to maintain system balance and keep pressure output stable when it is disturbed by another motor; improve control accuracy: realize multi-objective control, reduce current and torque pulsation, and improve the dynamic and steady-state performance of the system.

[0092] The present invention controls the rotation of the cam 5 by controlling the position of the servo motor 6 through the control system, and squeezes the pressure sensing mechanism 2 around it, and changes the pressure between one side of the front roller 8 and the middle roller 10 by rotating the connecting rod arm and other structures, collects and detects the ground materials, and gives corresponding feedback to the control system according to the results of the material detection. The qualified materials are directly discharged, and the unqualified materials are given corresponding instructions to the corresponding servo motor 6 according to the judgment of the control system, and the rotation of the servo motor 6 is adjusted to adjust the pressure between the two sides of the front roller and the middle roller. The pressure sensing mechanism 2 designed according to stress and strain is used to detect and monitor the pressure between the rollers, and then according to the detected pressure, a pressure control system is designed, including the collection and calculation of the states of the two servo motors, feedforward compensation and decoupling control. The pressure difference is input to the two servo motors 6 through the decoupling coefficient of the decoupling control algorithm by making a difference between the pressures at both ends of the collected rollers, and becomes part of the control instructions of the two servo motors 6. It is dynamically compensated by the sliding mode controller, which is a very clever transmission structure and control method for pressure control. This solution uses a constant pressure decoupling control method to control the pressure between the rollers to remain near the set value, thereby improving the stability of control and meeting the high-precision requirements for control. It solves the impact of the output pressure of motor 2 on the disturbance of motor 1, and enables the three-roll grinder to keep the pressure at both ends near the input value in the pressure mode, thereby improving stability and thus improving the grinding quality and efficiency.

[0093] The method of the present invention can improve the grinding effect: by accurately controlling the pressure between the rollers, the material can be ground more effectively, and the appropriate pressure can make the material fully squeezed and rubbed between the rollers, thereby improving the grinding efficiency and grinding quality; protecting the rollers and equipment: pressure control helps to avoid excessive pressure between the rollers, which can prevent the rollers from being damaged or excessively worn, and extend the service life of the equipment; adapting to different materials: different materials require different grinding pressures. Through the pressure control mode, the pressure between the rollers can be easily adjusted to meet the grinding requirements of different materials; realizing automatic operation: the pressure control mode can be combined with the automatic control system to realize the automation of the grinding process. This can not only reduce the burden on the operator, but also improve production efficiency and reduce the impact of human factors on product quality.

[0094] It should be noted that the terms such as "upper", "lower", "left", "right", "front", "back", etc. cited in the invention are only for the convenience of description and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should be regarded as the scope of implementation of the present invention without substantially changing the technical content.

[0095] The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should be regarded as the protection scope of the present invention.

Claims

1. A transmission structure for pressure control of a three-roller mill, characterized in that: The invention comprises a machine body (13), a front roller adjustment frame, a rear roller adjustment frame, a front roller (8), a middle roller (10), a rear roller (11), a cam driving mechanism and a pressure collecting mechanism, wherein the cam driving mechanism comprises a cam (5) and a servo motor (6), the two ends of the middle roller (10) are arranged on the machine body (13), the front roller (8) is rotatably arranged on the front roller adjustment frame via a front roller center axis (7), the front roller adjustment frame is rotatably arranged on the machine body (13) in front of the middle roller (10) via a rotating fulcrum (9), and the front roller center axis (7) and the rotating fulcrum (9) on the front roller adjustment frame are staggered, and the rear roller (11) is rotatably arranged on the rear roller center axis (12) via a rear roller center axis (13). The rear roller adjustment frame is rotatably arranged on a machine body (13) at the rear side of the middle roller (10) via a rotating fulcrum (9), and the rear roller central axis (12) is staggered with the rotating fulcrum (9) on the rear roller adjustment frame; a servo motor (6) is respectively arranged at the lower end of the front roller adjustment frame and the rear roller adjustment frame, and the output end of the servo motor (6) is respectively connected to the middle of a cam (5); the pressure collection mechanism is fitted on the side of the cam (5) and is used for the cam (5) to resist and collect the pressure of the contact surface; the servo motor (6) is used to drive the cam (5) to rotate and drive the front roller (8) or the rear roller (11) to move closer to or away from the middle roller (10).

2. The transmission structure for pressure control of a three-roll mill according to claim 1, characterized in that: The front roller adjustment frame and the rear roller adjustment frame both comprise a rotating link arm (1), the two ends of the front roller (8) being rotatably arranged on the rotating link arm (1) via the front roller center axis (7), the rotating link arms (1) at the two ends of the front roller (8) being rotatably arranged on the machine body (13) at the front side of the middle roller (10) via a rotating fulcrum (9), and the rotating fulcrum (9) on the front roller adjustment frame being located above and offset from the front roller center axis (7); the two ends of the rear roller (11) being rotatably arranged on the rotating link arm (1) via the rear roller center axis (12), the rotating link arms (1) at the two ends of the rear roller (11) being rotatably arranged on the machine body (13) at the rear side of the middle roller (10) via a rotating fulcrum (9), and the rotating fulcrum (9) on the rear roller adjustment frame being located above and offset from the rear roller center axis (12).

3. The transmission structure for pressure control of a three-roll mill according to claim 1, characterized in that: The pressure collection mechanism comprises a pressure sensing mechanism (2) and a bolt B (3); the pressure sensing mechanism (2) is mounted on the machine body (13) via the bolt B (3); and the collection end of the pressure sensing mechanism (2) is always in contact with the side of the cam (5).

4. The transmission structure for pressure control of a three-roll mill according to claim 3, characterized in that: The pressure sensing mechanism (2) comprises a metal block, a contact arc surface (15), a stress strain gauge (14) and a stress strain acquisition circuit (16); the upper end of the metal block is provided with a contact arc surface (15) which is always in contact with the side of the cam (5); the metal block is provided with a groove symmetrically arranged on both sides close to and far from the cam (5) below the contact arc surface (15); a stress strain gauge (14) for sensing deformation is arranged in the groove; the stress strain acquisition circuit (16) is connected to the stress strain gauge (14) for acquiring and transmitting signals.

5. The transmission structure for pressure control of a three-roll mill according to claim 3, characterized in that: The pressure collection mechanism further comprises a bolt A (4), and the pressure sensing mechanism (2) is mounted on the machine body (13) via a bolt B (3) and a bolt A (4) offset from the bolt B (3).

6. The transmission structure for pressure control of a three-roll mill according to claim 1, characterized in that: A cam driving mechanism is provided at the lower end of each of the two sides of the front roller (8) of the front roller adjustment frame, and a cam driving mechanism is provided at the lower end of each of the two sides of the rear roller (11) of the rear roller adjustment frame, and each of the cam driving mechanisms is provided with a corresponding pressure collection mechanism.

7. The transmission structure for pressure control of a three-roll mill according to claim 1, characterized in that: The cam (5) is a rotationally linearized cam designed according to an involute.

8. The transmission structure for pressure control of a three-roll mill according to claim 1, characterized in that: It also includes a rotating mechanism, which is respectively connected to and drives the front roller (8) and the rear roller (11) to rotate.

9. A control method for a transmission structure for pressure control of a three-roll mill according to any one of claims 1 to 8, characterized in that: The invention also comprises a constant pressure decoupling control system and a material output detection system. The constant pressure decoupling control system sends instructions to the servo motor (6) of the corresponding cam driving mechanism through the CAN bus, and controls the rotation of the cam (5) thereon through the servo motor (6). The cam (5) correspondingly drives the left side or right side of the front roller adjustment frame or the left side or right side of the rear roller adjustment frame as the transmission mechanism to move, so as to adjust the distance between the two sides of the front roller (8) or the rear roller (11) and the middle roller (10). The material output detection system is used to detect whether the material output is qualified. If the detection is qualified, the material is directly discharged. If the detection is unqualified, the constant pressure decoupling control system is fed back according to the detection result to adjust the rotation speed of the servo motor (6) on both sides of the front roller (8) or the rear roller (11), so as to control the distance between the two sides of the front roller (8) or the rear roller (11) and the middle roller (10), until the material output is qualified.

10. A control method according to claim 9, characterized in that: The constant pressure decoupling control system comprises a touch screen system for monitoring and controlling a servo motor (6), a pressure ring sliding mode controller and a decoupling controller, the lower ends of both sides of the front roller adjustment frame and the rear roller adjustment frame are respectively provided with a cam driving mechanism and a pressure collection mechanism, the touch screen system sends instructions to the servo motor (6) of the corresponding cam driving mechanism via a CAN bus, and controls the rotation of the cam (5) thereon via the servo motor (6); The actual positions of the two servo motors (6) on both sides of the front roller adjustment frame are collected by using a touch screen system, the actual position of each servo motor (6) is subtracted from the input position to obtain a tracking error, the actual position of one of the servo motors (6) is multiplied by a disturbance coefficient to obtain a load disturbance of the other servo motor (6), the actual position is added to the actual position of the original servo motor (6) and then multiplied by the stress-strain pressure coefficient to obtain an actual pressure value, and the actual pressure values ​​of the two servo motors (6) are subtracted to obtain a synchronization error; The two servo motors (6) are divided into servo motor A and servo motor B. For servo motor A, the input is the pressure setting value. The pressure is converted into a position value through a calibrated stress strain coefficient and input into servo motor A. The actual position of servo motor B is multiplied by the disturbance coefficient as the load disturbance of servo motor A. The actual position of servo motor A plus the load disturbance is fed back to the input end, and the position tracking error of servo motor A is obtained by subtracting the input position. The actual position of servo motor A and the load disturbance are added and multiplied by the stress strain gain to obtain the actual pressure value of servo motor A. The difference between the actual pressure value of servo motor A and the actual pressure value of servo motor B is used as the input of the decoupling controller. The decoupling controller feeds back the pressure difference after the change on both sides to the pressure ring sliding mode controller through the decoupling coefficient to adjust the position of the servo motors (6) on both sides, so that the pressure on both sides of the front roller (8) tends to be stable after a short period of fluctuation. The rear roller (11) adopts the same control.

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