Dynamic regulation and control method for material screening equipment

Abstract

The invention relates to a dynamic regulation and control method for material screening equipment, belongs to the technical field of material screening, and solves the problem that in the prior art, screening equipment cannot be accurately controlled. The method comprises the following steps that S1, material screening equipment is built, and a test scheme is designed; s2, performing a test according to the test scheme to obtain screening data; s3, according to the obtained screening data, constructing a screening penetration kinetic model; s4, performing a response surface test according to the obtained screening data and the screening penetration kinetic model; and S5, performing dynamic regulation and control on the material screening equipment according to the screening penetration dynamic model and the response surface test data. According to the method, the material screening equipment is built, the screening penetration test is conducted through the material screening equipment, and the screening penetration dynamic model is built and used for achieving accurate regulation and control over the screening process.

Description

Technical Field

[0001] The invention relates to the technical field of material screening, and in particular to a dynamics control method for material screening equipment. Background Art

[0002] The screening dynamics model of the screening process plays a vital role in the automated control of screening equipment. The screening dynamics model mainly studies the relationship between screening efficiency and screening time and key parameters of the screen surface during the screening process, so that the control system can perform accurate calculations and predictions based on these relationships. At present, the expression of the screening dynamics model of the screening process is mostly empirical model, and the inaccurate screening dynamics model cannot achieve accurate control of the screening equipment. Summary of the invention

[0003] In view of the above analysis, an embodiment of the present invention aims to provide a method for dynamic control of material screening equipment, so as to solve the problem that the screening equipment in the prior art cannot be accurately controlled.

[0004] The present invention provides a material screening equipment dynamics control method, comprising the following steps:

[0005] S1: Build material screening equipment and design test plan;

[0006] S2: Conducting a test according to the test plan to obtain screening data;

[0007] S3: constructing a screening kinetics model according to the obtained screening data;

[0008] S4: performing a response surface experiment based on the obtained screening data and the screening kinetic model;

[0009] S5: Performing dynamic control on the material screening equipment according to the screening dynamics model and the response surface test data.

[0010] Furthermore, in step S1, the material screening equipment includes an elastic screen plate and a moving column, two elastic screen plates are symmetrically arranged on both sides of the moving column, one end of the elastic screen plate is connected to the moving column, and the other end of the elastic screen plate is fixed.

[0011] Furthermore, the material screening equipment includes an excitation unit, and the magnitude and frequency of the current of the excitation unit are adjusted to adjust the movement amplitude, movement frequency and screen surface tension of the elastic screen plate.

[0012] Furthermore, in step S1, the test scheme includes a first round of screening test and a second round of screening test, and in the first round of screening test, the mass of the material on the screen in the initial state of each test is adjusted.

[0013] Furthermore, in the second round of screening test, the mass of the material on the screen remains unchanged in the initial state of the test, and any one of the movement frequency, movement amplitude and screen surface tension of the elastic screen plate is adjusted for each test.

[0014] Furthermore, step S3 specifically includes the following steps:

[0015] S31: obtaining a mathematical model between the screening rate and time and the screening rate coefficient according to the screening data obtained in the first round of screening test;

[0016] S32: Based on the screening data obtained in the second round of screening test, a mathematical model is fitted to describe the movement frequency, movement amplitude, screen surface tension and the screening rate coefficient of the elastic screen plate.

[0017] Furthermore, in step S31, the screening process includes a rapid screening stage and a stable screening stage, and the screening data are fitted in stages to obtain mathematical models between the screening rate, time and screening rate coefficient of the rapid screening stage and the stable screening stage, respectively.

[0018] Furthermore, step S5 specifically includes:

[0019] S51: obtaining the material mass on the screen of the elastic screen plate in the initial state, and a mathematical model of the target screen penetration rate and time;

[0020] S52: Calculate the target screening rate coefficient according to the relationship between the target screening rate and time and the mathematical model obtained in step S31.

[0021] Furthermore, step S5 further includes:

[0022] S53: Determine the movement frequency, movement amplitude and screen surface tension of the elastic screen plate according to the target screening rate coefficient and the response surface test data obtained in step S4, and adjust the screening process of the material screening equipment according to the movement frequency and movement amplitude.

[0023] Furthermore, in step S3, the screening dynamics model includes the relationship between the screening rate and time, the screening rate coefficient, and the relationship between the movement frequency, movement amplitude, screen surface tension and the screening rate coefficient of the material screening equipment.

[0024] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0025] (1) The present invention builds a material screening device and uses the material screening device to perform a screening test to test the relationship between the amount of screening and the screening time during the screening process (or the relationship between the increase rate of the undersize product and the screening time during the screening process), that is, the screening speed. Based on this, a screening kinetic model is established to achieve precise control of the screening process. Through two rounds of screening tests and the previous round of response surface tests, the relationship between the key parameters of the material screening equipment and the screening rate coefficient can be obtained, thereby achieving precise control of the screening process of the material screening equipment.

[0026] (2) The present invention provides displacement excitation for the elastic screen plate through an excitation unit. There is no exciting force, and the screening of materials is achieved only by relying on electromagnetic force and displacement drive. The auxiliary screening unit is used for the material to pass through the elastic screen plate, and can adapt to various environments (such as microgravity environment, ordinary environment) with strong environmental adaptability. The movement frequency, amplitude and screen surface tension of the elastic screen plate can be adjusted by adjusting the frequency and voltage of the current to adapt to different material properties.

[0027] (3) The fixed column and the movable column of the present invention are arranged in parallel, the fixed column is arranged between the two movable columns, the elastic screen plate is arranged between the fixed column and the movable column, the two opposite sides of the elastic screen plate are respectively connected to the fixed column and the movable column, the two ends of the movable column are connected to the permanent magnet of the movable column, the permanent magnet of the movable column is arranged in the excitation track to reciprocate, drive the elastic screen plate to stretch and tighten or shrink and relax, thereby being able to change the size of the screen holes on the elastic screen plate, and effectively avoiding the blockage of the screen holes. During the reciprocating motion of the movable column, one of the elastic screen plates is driven to stretch and tighten, and the other elastic screen plate is driven to shrink and relax at the same time. The middle part of the relaxed elastic screen plate will sag, and in the process of being stretched and tightened again, the material will be thrown up, so that the material is loosened, the screening permeability of the material is improved, and the screening efficiency is improved.

[0028] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0030] Figure 1 It is a flow chart of dynamic control of material screening equipment in a specific embodiment;

[0031] Figure 2 It is a structural schematic diagram of a material screening device in a specific embodiment;

[0032] Figure 3 It is a structural schematic diagram of a lifting mechanism of a specific embodiment.

[0033] Figure 4 is a schematic diagram of the connection structure of the sieve plate unit and the excitation unit in a specific embodiment;

[0034] Figure 5 It is a schematic diagram of the connection structure of part of the sieve plate unit and part of the excitation unit in a specific embodiment;

[0035] Figure 6 It is a schematic diagram of the structure of some excitation units of a specific embodiment.

[0036] Reference numerals:

[0037] 1-screen plate unit; 11-elastic screen plate; 12-moving column; 13-fixed column; 14-first enclosure plate; 15-second enclosure plate; 16-third enclosure plate; 17-fourth enclosure plate; 18-material collecting trough; 19-top cover;

[0038] 2-excitation unit; 21-magnetic suspension seat; 22-moving column permanent magnet; 23-excitation track; 24-permanent magnet; 25-coil; 26-controller;

[0039] 3- auxiliary screening unit; 31- protective shell; 32- sliding track; 33- moving block; 34- guide block; 35- wire rope; 36- first motor; 37- winch. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of the present invention and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0041] A specific embodiment of the present invention, as Figure 1 As shown, a material screening equipment dynamics control method is disclosed, comprising the following steps:

[0042] S1: Build material screening equipment to obtain the screening dynamics model and design the experimental plan;

[0043] S2: Conducting a test according to the test plan designed in step S1 to obtain screening data;

[0044] S3: constructing a screening dynamics model of the material screening equipment according to the screening data obtained in step S2;

[0045] S4: According to the screening data obtained in step S2 and the screening dynamics model obtained in step S3, a response surface test is performed to obtain the optimal value combination of the motion frequency, motion amplitude and screen surface tension of the test device (i.e., the material screening device) corresponding to different screening rate coefficients;

[0046] S5: Automatically controlling the screening process of the material screening equipment according to the screening dynamics model obtained in step S2 and the optimal value combination obtained in step S4;

[0047] The screening dynamics model in step S3 includes the relationship between the screening rate and time, the screening rate coefficient, and the relationship between the movement frequency, movement amplitude, screen surface tension and the screening rate coefficient of the test device.

[0048] Specifically, the specific structure of the material screening equipment in step S1 is as follows: Figure 2 As shown, the material screening equipment includes a sieve plate unit 1, an excitation unit 2 and an auxiliary screening unit 3. The excitation unit 2 and the auxiliary screening unit 3 are both connected to the sieve plate unit 1. The excitation unit 2 provides displacement excitation for the elastic sieve plate 11 of the sieve plate unit 1. The auxiliary screening unit 3 is used to assist material screening, and is particularly suitable for screening in a microgravity environment.

[0049] In this embodiment, the excitation unit 2 provides displacement excitation for the elastic screen plate 11. There is no exciting force, and high-efficiency screening of materials is achieved by relying on electromagnetic force and displacement drive. The auxiliary screening unit 3 is used to assist the material in screening, and is particularly suitable for passing through the elastic screen plate 11 in a microgravity environment, so that the equipment has strong environmental adaptability (it can be used in microgravity environments and gravity conditions), and the movement frequency, amplitude and screen surface tension of the elastic screen plate 11 can be adjusted by adjusting the frequency and voltage of the current to adapt to different material properties.

[0050] Combination Figure 4 and Figure 5As shown, the sieve plate unit 1 includes two elastic sieve plates 11, a moving column 12 and two fixed columns 13, the two elastic sieve plates 11 are arranged in parallel, the two fixed columns 13 are arranged in parallel, the fixed column 13 and the moving column 12 are arranged in parallel, the fixed column 13 is arranged between the two moving columns 12, the elastic sieve plate 11 is arranged between the fixed column 13 and the moving column 12, the two elastic sieve plates 11 are connected to one moving column 12 at the same time, and the two fixed columns 13 are respectively connected to the two elastic sieve plates 11, that is, one fixed column 13 is connected to one elastic sieve plate 11. The two opposite sides of the elastic sieve plate 11 are respectively connected to the fixed column 13 and the moving column 12. When the moving column 12 moves between the two fixed columns 13, the elastic sieve plate 11 is driven to stretch or contract and relax, thereby changing the size of the sieve holes on the elastic sieve plate 11, effectively avoiding the blockage of the sieve holes, improving the screening performance of the material, and thus improving the screening efficiency. Preferably, the elastic sieve plate 11 is made of polyurethane polymer materials commonly used in industrial screening equipment.

[0051] In order to achieve the fixation of the fixed column 13 and the collection of materials, combined with Figure 2 and Figure 4 As shown, the sieve plate unit 1 also includes a first enclosure plate 14, a second enclosure plate 15, a third enclosure plate 16, a fourth enclosure plate 17 and a material collection trough 18. The first enclosure plate 14 and the second enclosure plate 15 are arranged in parallel, and the third enclosure plate 16 and the fourth enclosure plate 17 are arranged in parallel. A rectangular cylinder is formed by the first enclosure plate 14, the second enclosure plate 15, the third enclosure plate 16 and the fourth enclosure plate 17, and the material collection trough 18 is arranged below the rectangular cylinder. The two ends of the fixed column 13 are fixedly connected to the first enclosure plate 14 and the second enclosure plate 15 respectively. Figure 3 As shown, the sieve plate unit 1 further comprises a top cover 19, which is arranged on the top of the rectangular cylinder.

[0052] Combination Figure 4 , Figure 5 and Figure 6 As shown, the excitation unit 2 includes two magnetic suspension seats 21 and a moving column permanent magnet 22. The two magnetic suspension seats 21 are respectively installed on the inner side of the first enclosure plate 14 and the inner side of the second enclosure plate 15. The two magnetic suspension seats 21 are symmetrical about the symmetric plane of the first enclosure plate 14 and the second enclosure plate 15. Figure 6 As shown, the magnetic suspension seat 21 is provided with an excitation track 23, which is arranged along the length of the magnetic suspension seat 21, and the moving column permanent magnet 22 is arranged in the excitation track 23, and the moving column permanent magnet 22 can reciprocate in the excitation track 23. The two ends of the moving column 12 are respectively connected to a moving column permanent magnet 22. The excitation track 23 is formed by a groove arranged on the magnetic suspension seat 21.

[0053] In this embodiment, the two ends of the moving column 12 are respectively connected to a moving column permanent magnet 22, and the moving column permanent magnet 22 is arranged in the excitation track 23 to do reciprocating motion. The excitation track 23 is arranged horizontally. Driven by the moving column permanent magnet 22, the moving column 12 reciprocates in the horizontal plane, thereby driving the two elastic screen plates 11 connected thereto to stretch and tighten or shrink and relax. When the elastic screen plates 11 are in the process of reciprocating stretching, tightening, shrinking and relaxing, the size of the screen holes of the elastic screen plates 11 changes, which can avoid the material from blocking the screen holes and realize efficient screening of the material. During the reciprocating motion of the moving column 12, one of the elastic screen plates 11 is stretched and tightened, while the other elastic screen plate 11 is contracted and relaxed. The middle part of the relaxed elastic screen plate 11 will sag. In the process of being stretched and tightened again, the material will be thrown up, so that the material is loosened, the material permeability is improved, and the screening efficiency is improved.

[0054] like Figure 6 As shown, the excitation unit 2 further includes a permanent magnet 24, and two permanent magnets 24 are respectively arranged on both sides of the moving column permanent magnet 22, and the permanent magnet 24 located on one side of the moving column permanent magnet 22 has opposite magnetic properties to the end of the moving column permanent magnet 22 adjacent thereto. Exemplarily, the left end of the moving column permanent magnet 22 is of N grade, and the right end is of S grade, the end of the permanent magnet 24 located at the left end of the excitation track 23 facing the moving column permanent magnet 22 is of N grade, and the end of the permanent magnet 24 located at the right end of the excitation track 23 facing the moving column permanent magnet 22 is of S grade. Preferably, the moving column permanent magnet 22 and the permanent magnet 24 are both permanent magnets.

[0055] Preferably, the excitation track 23 is a cylindrical groove, and accordingly, the moving column permanent magnet 22 is cylindrical, the radius of the excitation track 23 is slightly larger than the radius of the moving column permanent magnet 22, and the length of the excitation track 23 after the permanent magnet 24 is arranged is larger than the thickness of the moving column permanent magnet 22, so that sufficient space is left for the moving column permanent magnet 22 to reciprocate in the excitation track 23. The radius of the permanent magnet 24 is equal to the radius of the excitation track 23.

[0056] Combination Figure 4 , Figure 5 and Figure 6 As shown, the excitation unit 2 also includes a coil 25, which is arranged outside the excitation track 23 and adjacent to one of the permanent magnets 24 to form a driving magnetic field. The center of the coil 25 coincides with the center of the excitation track 23 in the axial direction. The coil 25 located on the first enclosure plate 14 side and the coil 25 located on the second enclosure plate 15 side are connected together to achieve synchronous and unidirectional movement of the moving column permanent magnets 22 on both sides.

[0057] Combination Figure 2 and Figure 4As shown, the excitation unit 2 also includes a controller 26 and a second motor (not shown in the figure), which are installed on the outside of the first enclosure plate 14. The output end of the second motor is connected to the coil 25 for energizing the coil 25. The controller 26 is used to adjust the current of the coil 25 to generate a magnetic field force, thereby driving the moving column permanent magnet 22 to reciprocate in the excitation track 23, thereby driving the moving column 12 to move, so as to achieve the displacement excitation effect on the elastic screen plate 11. The controller 26 is mainly used to adjust the magnitude and frequency of the current.

[0058] like Figure 1 and Figure 2 As shown, the auxiliary screening unit 3 includes a protective shell 31 and a sliding track 32. The protective shell 31 is sleeved on the outside of the rectangular cylinder and the material collection trough 18. There are four sliding tracks 32. The four sliding tracks 32 are located on both sides of the rectangular cylinder in pairs. The sliding tracks 32 are connected to the inner wall of the protective shell 31 and are vertically arranged. Specifically, two sliding tracks 32 are arranged on the side adjacent to the first enclosure plate 14 of the protective shell 31, and two sliding tracks 32 are arranged on the side adjacent to the second enclosure plate 15 of the protective shell 31. The whole formed by the rectangular cylinder and the material collection trough 18 can reciprocate up and down along the sliding tracks 32. It should be noted that the top cover 19 is no longer needed at this time.

[0059] The material screening equipment provided in this embodiment, when in a microgravity environment, the material no longer moves vertically downward due to gravity, and the particle group is dispersed in the space system. The lifting assembly drives the screen plate unit 1 and the excitation unit 2 to make up and down reciprocating movements, driving the elastic screen plate 11 to contact the material in the protective shell 31 and continuously drive (cut) the material, causing the material to collide with the elastic screen plate 11 and penetrate the screen, thereby achieving high-efficiency screening in a microgravity environment. It should be noted that when in gravity conditions, the auxiliary screening unit 3 can also be used to achieve efficient screening of materials.

[0060] like Figure 1 and Figure 2As shown, the auxiliary screening unit 3 also includes a moving block 33, and four moving blocks 33 are provided. The four moving blocks 33 are respectively matched with four sliding rails 32, two moving blocks 33 are connected to the first protective plate 14, and the other two moving blocks 33 are connected to the second protective plate 15. The moving blocks 33 slide along the sliding rails 32, thereby driving the screen plate unit 1 and the excitation unit 2 to move up and down in the protective shell 31. The lifting assembly also includes a guide block 34, a steel wire rope 35, a first motor 36, a winch 37 and a tension spring (not shown in the figure). The guide block 34 is arranged at the top of the sliding rail 32, the first motor 36 and the winch 37 are arranged outside the protective shell 31, the winch 37 is connected to the output shaft of the first motor 36, one end of the steel wire rope 35 is connected to the winch 37, and the other end passes through the guide block 34 and is connected to the top of the moving block 33. The guide block 34 is provided with an arc-shaped groove for the steel wire rope 35 to pass through, the upper end of the tension spring is connected to the lower end of the moving block 33, and the lower end of the tension spring is connected to the bottom of the sliding rail 32.

[0061] In this embodiment, the winch 37 is driven to rotate by the first motor 36 to wind or release the wire rope 35, thereby driving the moving block 33 to move along the sliding track 32. When the winch 37 winds the wire rope 35, it drives the moving block 33 to move upward along the sliding track 32. When the winch 37 releases the wire rope 35, the moving block 33 moves downward under the action of the tension spring, thereby realizing that the elastic screen plate 11 contacts and continuously cuts the material during the up and down reciprocating motion, thereby causing the material to collide with and penetrate the elastic screen plate 11. At the same time, the moving column permanent magnet 22 reciprocates in the excitation track 23, thereby driving the moving column 12 to move, realizing the displacement excitation of the elastic screen plate 11, and the up and down reciprocating motion of the elastic screen plate 11 is coupled with the displacement excitation in the horizontal direction, thereby realizing the screening of materials under various gravity environments and improving the screening efficiency.

[0062] In step S1, the test plan includes a first round of screening test and a second round of screening test.

[0063] In the first round of screening tests, the test device remained unchanged, that is, the movement frequency (f), movement amplitude (X) and screen tension (Δl) of the test system were fixed to a conventional value, and the mass w0 of the fine-grained material in the screen material at the initial state of each test was adjusted.

[0064] In the second round of screening test, the mass w0 of the fine-grained material in the screen material remains unchanged in the initial state of the test, and a single-factor item-by-item optimization test method is adopted to adjust any one of the movement frequency, movement amplitude, and screen surface tension of the elastic screen plate 11 in each test. For example, the test parameters are designed according to the contents of Table 1.

[0065] Table 1 Test parameters

[0066]

[0067] The first round of screening test and the second round of screening test in step S2 both specifically include the following steps:

[0068] S21: Set the movement amplitude of the elastic screen plate 11, pour in the material, and turn on the power. Turn on the test equipment, and adjust the frequency of the current of the coil 25 to 12-18Hz, preferably 13.5Hz, through the magnetic controller 26. The mixed material is poured from the top of the elastic screen plate 11. In each test, the mass w0 of the fine-grained material in the poured screen material is selected according to the test scheme in step S1. The movement frequency, movement amplitude, and screen tension of the elastic screen plate 11 are also set according to the test scheme in step S1.

[0069] S22: Screening materials. The excitation unit 2 drives the movable column 12 connected thereto to perform periodic reciprocating motion, so that the elastic screen plate 11 repeatedly switches between the tensioned and relaxed states.

[0070] The materials are graded in the material screening equipment according to the mesh size of the elastic screen plate 11: the fine-grained materials smaller than the mesh size pass through the mesh and fall into the under-mesh material collecting trough 18 to become under-mesh products; the coarse-grained materials larger than the mesh size remain on the screen surface to become over-mesh products.

[0071] S23: The weighing sensor measures the amount of fine-grained material that passes through the screen, that is, the weight of the material falling into the material collecting trough 18, in real time and dynamically, and feeds the data back to the data acquisition terminal. It can be understood that a load-bearing device is provided below the material collecting trough 18.

[0072] Step S3 specifically includes the following steps:

[0073] S31: Based on the screening data obtained in the first round of screening test, the relationship between the screening rate-time and the screening rate coefficient is obtained.

[0074] S32: Based on the screening data obtained in the second round of screening test, a mathematical model is fitted to describe the relationship between the movement frequency, movement amplitude, screen surface tension and screening rate coefficient of the elastic screen plate 11.

[0075] In step S31, the screening process is divided into a rapid screening stage and a stable screening stage, and the screening data is fitted in stages to obtain the relationship between the screening rate-time and the screening rate coefficient in the rapid screening stage and the stable screening stage respectively.

[0076] Specifically, the measured data is transmitted to the computer in real time to obtain the screening rate of fine-grained materials. Based on the test data, the Levenberg-Marquarelt algorithm is used for least squares regression iteration to obtain the relationship between screening rate and time.

[0077] The relationship between the screening rate and time is specifically obtained as follows:

[0078] The screening process is divided into two stages: let dw be the micro-element mass of the undersize produced in the micro-element of time dt, then dw / dt represents the output of the undersize per unit time, which is called the undersize through-screening rate; the screening process is divided into a rapid through-screening stage (stage I) and a stable through-screening stage (stage II) with the moment when the through-screening rate, i.e., dw / dt, reaches the maximum as the dividing point. In the rapid through-screening stage (stage I), the content of fine particles in the oversize particle group is high, and the through-screening amount in this stage is large.

[0079] According to the segmented results, the relationship between the screening rate and time is obtained by segmented fitting: in the rapid screening stage (stage I), according to the traditional vibration screening process dynamics equation, a single-phase exponential decay function with a time parameter is used to regress and fit the stage I screening rate curve under different conditions randomly selected, and the obtained mathematical correlation is as follows:

[0080]

[0081] Among them, y1 is the screening rate at this stage, g / s; t1 is the screening time, s; w0 is the mass of fine particles in the screen material at the initial state of this stage, g; K1 is the screening rate coefficient at this stage, s -1 .

[0082] In the stable screening stage (stage II), when the screening reaches the stable stage, the screening rate is proportional to the mass w of the fine-grained material retained in the material above the screen surface, that is:

[0083]

[0084] By integrating, simplifying and sorting, we can get the relationship between the screening rate and time in the stable screening stage:

[0085]

[0086] y2 is the screening rate at this stage, g / s; t2 is the screening time, s; w1 is the mass of fine particles in the screen material at the initial state of this stage, g; K2 is the screening rate coefficient at this stage, s -1 .

[0087] Based on nonlinear least squares regression and calculus derivation, the mathematical expressions of the screening rates in the rapid screening stage and the stable screening stage are obtained:

[0088]

[0089] Among them, K1 and K2 are the screening rate coefficients of the two stages of the screening process, s -1; t0 is the moment of the dividing point between the two stages, s; y is the screening rate in this stage, g / s; t is the screening time, s; w0 is the mass of the fine-grained material in the on-screen material at the initial state of stage I, g; w1 is the mass of the fine-grained material in the on-screen material at the initial state of stage II, g.

[0090] It can be seen from the above relationship that when the parameters of the screening raw materials are determined, the screening rate coefficients K1 and K2 directly affect the size of the screening rate. Therefore, the screening rate coefficient is used as a kinetic evaluation index of the particle group screening process.

[0091] The screening rate coefficients K1 and K2 are mainly determined by the structural parameters of the screening equipment. Therefore, it is necessary to further explore the influence of key parameters on the screening rate coefficients of the screening process of material screening equipment.

[0092] In step S32, a mathematical model describing the relationship between the movement frequency, movement amplitude, and screen surface tension of the elastic screen plate and the screening rate coefficient is fitted based on the screening data obtained in the second round of screening test. In this stage, the method in step S31 is used to divide the screening process into a rapid screening stage and a stable screening stage, and the screening data is fitted in stages to obtain the relationship between the screening rate coefficients K1 and K2 in the rapid screening stage and the stable screening stage and the movement frequency f, movement amplitude X, and screen surface tension Δl of the test system.

[0093] For the evaluation index K1 of the rapid screening stage: the test scheme is determined according to the test factor level table (in the test design, the factor refers to the amount that affects the test assessment index, and the level refers to the different values ​​of each factor in the test), and different sequential models (Mean vs Total, Linear vs Mean, 2FI vs Linear, Quadratic vs 2FI, Cubic vs Quadratic, Residual) are used to fit its data. The P value of the quadratic polynomial is the smallest (P value: Prob. is a parameter used to determine the result of the hypothesis test (usually 0.05)), and the quadratic polynomial mathematical association model between the stage I screening rate coefficient and the key parameters is established as follows:

[0094]

[0095] For the evaluation index K2 of the stable screening stage: Similarly, the test plan was determined according to the test factor level table, and different sequential models (Mean vs Total, Linear vs Mean, 2FI vs Linear, Quadratic vs 2FI, Cubic vs Quadratic, Residual) were used to fit the data. The P value of the quadratic polynomial was the smallest, and the quadratic polynomial mathematical association model between the stage I screening rate coefficient and the key parameters was established as shown below:

[0096]

[0097] When the screening raw material parameter w0 is determined, the screening rate coefficients K1 and K2 directly affect the size of the screening rate, and are used as the particle group screening process dynamics index to evaluate the particle group screening effect. Therefore, by constructing the relationship between the screening rate coefficient and the screen surface parameters, the relationship between the screen surface parameters and the screening rate can be analyzed, thereby obtaining the screening dynamics model.

[0098] In step S4, a response surface test is performed based on the screening data obtained in step S2 and the screening dynamics model obtained in step S3, and the optimal value combination of the motion frequency, motion amplitude and screen surface tension of the test device corresponding to different screening rate coefficients is obtained. In this round of experiments, the optimal combination of motion frequency f, motion amplitude X, and screen surface tension Δl corresponding to different screening rate coefficients K1 and K2 is obtained through computer simulation.

[0099] The response surface test of the present invention is a three-factor three-level test. In the response surface test, the combination of the movement frequency f, the movement amplitude X and the screen surface tension Δl of the elastic screen plate in each test is adjusted.

[0100] Specifically, the value range of each factor is determined through the second round of screening test, i.e. single factor test (see Table 1). Appropriate tools (software) are selected to conduct experimental design for the selected values, and the experimental scheme table (see Table 2) is generated for the experiment, and the experimental data are analyzed using the response surface method.

[0101] Table 2 Experimental plan

[0102]

[0103]

[0104] Based on the second round of screening tests, i.e. single factor tests, the response surface methodology was used to explore the synergistic effect of the above three key parameters on the particle penetration in the screening process, establish a mathematical correlation model between the kinetic evaluation indicators of the particle penetration process and the structural parameters, and clarify the significance of the influence of key parameters on the indicators.

[0105] In step S5, the screening process of the material screening equipment is automatically controlled according to the screening dynamics model obtained in step S3 and the optimal value combination obtained in step S4, specifically including:

[0106] S51: Obtain the mass w0 of the fine-grained material in the screened material of the material screening device in the initial state and the target screen penetration rate-time relationship. The mass w0 of the fine-grained material in the screened material is the material amount in actual production. The target screen penetration rate-time relationship is the screening result expected in industrial production.

[0107] S52: Calculate the target screening rate coefficient according to the target screening rate-time relationship and the relationship obtained in step S31;

[0108] S53: Based on the target screening rate coefficient obtained in step S52 and the result of the optimal combination obtained in step S4, the optimal value combination of the movement frequency, movement amplitude and screen surface tension of the elastic screen plate 11 is obtained, and the frequency and magnitude of the current of the coil 25 of the excitation unit 2 of the material screening equipment are adjusted according to the optimal value combination, and then screening is started.

[0109] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for dynamic control of material screening equipment, characterized in that: The steps include: S1: Build material screening equipment and design test plan; S2: Conducting a test according to the test plan to obtain screening data; S3: constructing a screening kinetics model according to the obtained screening data; S4: performing a response surface experiment based on the obtained screening data and the screening kinetic model; S5: Performing dynamic control on the material screening equipment according to the screening dynamics model and the response surface test data.

2. The material screening equipment dynamics control method according to claim 1, characterized in that: In step S1, the material screening equipment comprises an elastic screen plate (11) and a moving column (12), wherein the two elastic screen plates (11) are symmetrically arranged on both sides of the moving column (12), one end of the elastic screen plate (11) is connected to the moving column (12), and the other end of the elastic screen plate (11) is fixed.

3. The material screening equipment dynamics control method according to claim 2, characterized in that: The material screening device comprises an excitation unit (2), and the magnitude and frequency of the current of the excitation unit (2) are adjusted to adjust the movement amplitude, movement frequency and screen surface tension of the elastic screen plate (11).

4. The material screening equipment dynamics control method according to claim 2, characterized in that: In step S1, the test scheme includes a first round of screening test and a second round of screening test. In the first round of screening test, the mass of the material on the screen in the initial state of each test is adjusted.

5. The material screening equipment dynamics control method according to claim 4, characterized in that: In the second round of screening test, the mass of the material on the screen remains unchanged in the initial state of the test, and any one of the movement frequency, movement amplitude and screen surface tension of the elastic screen plate (11) is adjusted for each test.

6. The material screening equipment dynamics control method according to claim 4, characterized in that: Step S3 specifically includes the following steps: S31: obtaining a mathematical model between the screening rate and time and the screening rate coefficient according to the screening data obtained in the first round of screening test; S32: Based on the screening data obtained in the second round of screening test, a mathematical model is fitted to describe the movement frequency, movement amplitude, screen surface tension and the screening rate coefficient of the elastic screen plate (11).

7. The material screening equipment dynamics control method according to claim 6, characterized in that: In step S31, the screening process includes a rapid screening stage and a stable screening stage, and the screening data are fitted in stages to obtain mathematical models between the screening rate, time and screening rate coefficient of the rapid screening stage and the stable screening stage respectively.

8. The material screening equipment dynamics control method according to claim 2, characterized in that: Step S5 specifically includes: S51: Obtaining the mass of the material on the screen of the elastic screen plate (11) in the initial state, and a mathematical model of the target screen penetration rate and time; S52: Calculate the target screening rate coefficient according to the relationship between the target screening rate and time and the mathematical model obtained in step S31.

9. The material screening equipment dynamics control method according to claim 8, characterized in that: Step S5 also includes: S53: Determine the movement frequency, movement amplitude and screen surface tension of the elastic screen plate (11) according to the target screening rate coefficient and the response surface test data obtained in step S4, and adjust the screening process of the material screening equipment according to the movement frequency, movement amplitude and screen surface tension.

10. The material screening equipment dynamics control method according to claim 1, characterized in that: In step S3, the screening dynamics model includes the relationship between the screening rate and time, the screening rate coefficient, and the relationship between the movement frequency, movement amplitude, screen surface tension and the screening rate coefficient of the material screening equipment.

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