A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil

Abstract

A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil, the method specifically follows the following steps: S1: establish real-time detection of the nitrogen content of each steel coil that has completed nitriding, S2: establish real-time monitoring of the detection results according to the established nitrogen content monitoring module, when the monitoring result triggers the early warning of the nitrogen content monitoring module, enter step S3, otherwise, according to the time series of the end of the production of the strip, monitor the real-time detection result of the nitrogen content of the next steel coil that has completed nitriding; S3: establish a prediction of the nitrogen content of the next steel coil to be produced according to the established prediction model. A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil of the present invention, based on the above-mentioned establishment of real-time nitrogen content monitoring detection and adjustment in the event of abnormality.

Description

Technical Field

[0001] The invention belongs to the technical field of gas nitriding during continuous annealing of plates, and in particular relates to a method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil. Background Art

[0002] Some special steel grades require nitriding treatment on the surface of the plate due to the requirements of plate surface performance, physical properties, etc. For example, some small household appliances, kitchen utensils, etc. have requirements for the corrosion resistance and wear resistance of the surface low-carbon steel materials, and surface nitriding treatment is required during the production process. In the continuous annealing production line of the plate, nitriding treatment mainly adopts gas nitriding. By introducing a certain amount of NH3+N2+H2 dry mixed gas into the continuous annealing furnace, under high temperature environment, NH3 decomposes active nitrogen atoms [N] on the surface of the steel strip, and then further penetrates into the steel through the pores of the substrate. The distribution of nitriding amount and nitrogen layer thickness in the steel strip will directly affect the surface performance of the plate and the quality of the final product.

[0003] For the study of gas nitriding process and mechanism, relevant scientific research institutions have been able to give some empirical formulas, but these pure mathematical models can only be used in some preset idealized nitriding environment conditions, and have more complex boundary conditions. In the industrialized large-scale production process, the alloy composition of the plate, annealing furnace conditions, equipment accuracy, operator skills and experience, etc. all have an impact on the final nitriding results. Therefore, in order to improve the product quality of strip steel, it is necessary to fully combine the actual production situation of the production site, and on the premise of making full use of the actual production data on site, explore a set of nitriding process control models based on big data theory that can be fully used.

[0004] At present, many sheet metal manufacturers have deployed and applied some detection and monitoring equipment and system software, which have played an important role in improving the stability of the nitriding process. However, they still cannot meet the needs of development. The data resources of various data systems and processes cannot be interconnected and shared; daily management cannot be closed-loop; the existing manual analysis and early warning work is inefficient and inaccurate; and there is a lack of effective guidance for nitriding process decision-making.

[0005] The invention application with application number: CN201610262343.4 discloses "a macroscopic gas-solid reaction kinetic model suitable for thin plates or block solids". The kinetic model includes a series of explicit function expressions with surface penetration, internal diffusion and the mixture of the two as the rate-controlling links; by substituting the kinetic data and reaction thermodynamic parameters of one or more actual reaction systems into the model formula, the characteristic time, apparent activation energy, optimal reaction temperature and corresponding shortest reaction time of the gas-solid reaction or its reverse reaction can be obtained by using a nonlinear fitting method, and the reaction kinetic mechanism can be analyzed at the same time.

[0006] The invention application with application number: CN201710763687.8 discloses "a nitriding control system", including a single-chip microcomputer, a nitriding furnace, a nitrogen raw material supply system and a gas analysis system; the nitrogen raw material supply system is connected to the air inlet of the nitriding furnace via an electric valve, and the single-chip microcomputer adjusts the opening of the electric valve via an electric valve regulator; the gas analysis system collects the gas in the nitriding furnace, analyzes the gas in the nitriding furnace, and outputs a measurement signal that can be recognized by the single-chip microcomputer; the single-chip microcomputer compares the measurement signal with a preset ideal value, obtains the deviation and the electric valve control amount corresponding to the deviation, and adjusts the nitrogen raw material supply.

[0007] The invention application with application number: CN202010742193.3 discloses "a controllable surface nitriding device and its use method". The device structure is composed of a vacuum device, a surface nitriding control mechanism and a nitrogen supply structure. The device structure is novel. Through this method, iron nitride can be circulated in a rotation direction and gradually adsorbed on the surfaces of multiple circular metal parts in the figure to produce a nitriding effect, so that materials such as stainless steel, titanium, and cobalt that were previously considered difficult to process can also be simply subjected to excellent surface hardening treatment. Iron nitride can be circulated in a rotation direction and gradually adsorbed on the surfaces of multiple circular metal parts to produce a nitriding effect, which solves the problem of uncontrollable and uneven distribution of iron nitride adsorption in the past during the nitriding process, and can further improve the mechanical properties of the workpiece surface. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a method for controlling and adjusting the gas nitriding process of a continuous annealing steel coil, and the technical solution thereof is as follows:

[0009] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil, characterized in that the control and adjustment method is specifically carried out in accordance with the following steps:

[0010] S1: Establish real-time detection of nitrogen content for each steel coil after nitriding.

[0011] S2: Establish real-time monitoring of the detection results according to the established nitrogen content monitoring module. When the monitoring results trigger the early warning of the nitrogen content monitoring module, enter step S3. Otherwise, monitor the real-time detection results of the nitrogen content of the next nitriding-finished steel coil according to the time sequence of the end of the production of the steel strip;

[0012] S3: Establish a prediction of the nitrogen content of the next steel coil to be produced according to the established prediction model.

[0013] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0014] After step S3, the nitrogen content of the next steel coil to be produced is set by using the set deviation correction control model.

[0015] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0016] The completed set value for the nitrogen content of the next steel coil to be produced is recorded as its actual value.

[0017] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0018] The prediction of the nitrogen content of the next steel coil to be produced in step S3 is characterized by the prediction model established for the ammonia flow rate of the next steel coil to be produced.

[0019] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0020] After step S3, the ammonia flow rate of the next steel coil to be produced is set by using the set deviation correction control model.

[0021] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0022] The completed set value for the nitrogen content of the next steel coil to be produced is recorded as its actual value.

[0023] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0024] Step S1 is specifically as follows:

[0025] Take the width of the steel coil as the length, cut a section along the length of the steel coil as the width, and form a rectangular sample.

[0026] By using a measuring instrument based on the inert gas melting principle, a total nitrogen content test is established for the sample to form a characterization of the total nitrogen content of the steel coil.

[0027] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0028] The warning described in step S2 is mapped by the set warning rules, and when the monitoring result meets any rule in the warning rules, the warning is triggered;

[0029] The warning rules are determined according to the following steps:

[0030] SS1: Based on the target requirements and allowable tolerance of total nitrogen content, a nitrogen content monitoring closed interval is formed for the same steel grade;

[0031] SS2: According to the control target and range requirements of the product process for nitrogen content, the nitrogen content monitoring closed interval is divided into intervals to form an early warning interval;

[0032] SS3: According to the response sensitivity requirements of the target value of total nitrogen content, the upper limit of the nitrogen monitoring closed interval, and the lower limit of the nitrogen monitoring closed interval, the corresponding response sensitivity is matched and set for each warning interval.

[0033] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0034] The time series of the end of the production of the steel coil described in step S2 is determined according to the following steps:

[0035] SF1: The process computer receives the unit inlet width, thickness, and ammonia flow rate of the steel coil sent by the basic automation control machine in real time; and records the real-time detection value of the nitrogen content of each steel coil completed based on step S1 in real time;

[0036] SF2: The process computer establishes the nitriding process steel coil number according to the steel coil production end time sequence;

[0037] SF3: The process computer establishes a one-to-one correspondence between the nitriding process coil number, the unit inlet width, thickness, ammonia flow rate of each coil, and the nitrogen content detection value of each coil, forming a time series containing the above information.

[0038] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0039] The warning described in step S2 is mapped by the set warning rules, and when the monitoring result meets any rule in the warning rules, the warning is triggered;

[0040] The warning rules are determined according to the following steps:

[0041] SS1: Based on the target requirements and allowable tolerance of total nitrogen content, a nitrogen content monitoring closed interval is formed for the same steel grade;

[0042] SS2: According to the control target and range requirements of the product process for nitrogen content, the nitrogen content monitoring closed interval is divided into intervals to form an early warning interval;

[0043] SS3: According to the target value of total nitrogen content, the upper limit of nitrogen content monitoring closed interval, and the response sensitivity requirements of the lower limit of nitrogen content monitoring closed interval, the number of continuous rolls in the corresponding interval is set;

[0044] The prediction of the nitrogen content of the next steel coil to be produced in step S3 is characterized by the prediction of the ammonia flow rate of the next steel coil to be produced established by the prediction model. The prediction of the ammonia flow rate is specifically as follows:

[0045]

[0046] in,

[0047] Fy: predicted flow rate of ammonia, unit: m 3 / h;

[0048] Ki: weighting coefficient;

[0049] Fi: Actual value of ammonia flow rate in volume i, unit: m 3 / h;

[0050] X: process target value of total nitrogen content in product; unit: ppm;

[0051] Ti: The total nitrogen content of each steel coil under the corresponding warning rule for this warning, unit: ppm;

[0052] Hi: the thickness of the roll, unit: mm;

[0053] Wi: the width of the roll, unit: mm;

[0054] H: predicted thickness of the steel coil, unit: mm;

[0055] W: predicted width of the steel coil, unit: mm;

[0056] m: the number of consecutive volumes corresponding to the corresponding warning rule.

[0057] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that it specifically includes the following steps:

[0058] SA1: The predicted value of ammonia flow rate completed according to the prediction model and the standard conversion value of the actual value of ammonia flow rate of the predicted volume are analyzed by the least square method to obtain the unknown number of linear fitting;

[0059] SA2: Substitute the predicted value of the ammonia flow rate and the value of the unknown variable obtained into the correction control model to calculate the ammonia flow set value for the next steel coil to be produced.

[0060] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0061] The deviation correction control model is:

[0062] F=Fy.f+b,

[0063] in,

[0064] F: actual value of ammonia flow rate of the predicted volume; unit: m 3 / h;

[0065] Fy: predicted flow rate of ammonia, unit: m 3 / h;

[0066] f: ammonia adjustment factor corresponding to the warning rule;

[0067] b: The error constant corresponding to the warning rule.

[0068] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0069] The standard conversion value of the actual value of the ammonia flow rate of the forecast volume, wherein the standard conversion value is specifically:

[0070]

[0071] in,

[0072] Fc: standard conversion value, unit: m 3 / h;

[0073] F: actual value of ammonia flow rate of the predicted volume, unit: m 3 / h;

[0074] X: target value of total nitrogen content in the predicted volume, unit: ppm;

[0075] T: actual value of total nitrogen content in the predicted volume, unit: ppm;

[0076] n: The number of warnings that occur under this warning rule.

[0077] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0078] The "detection of the total nitrogen content of the sample" is completed by setting multiple detection points on the sample and then processing the multiple detection points based on the weighted average concept.

[0079] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0080] The setting of multiple detection points on the template specifically includes: setting multiple detection points along the diagonal line of the template.

[0081] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0082] The processing of multiple detection points based on the weighted average idea is completed as follows:

[0083]

[0084] in,

[0085] T: actual value of total nitrogen content of steel coil, unit: ppm;

[0086] Ci: Nitrogen content test result value at each test point, unit: ppm;

[0087] Zi: weighting coefficient.

[0088] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0089] The weighting coefficient Zi is specifically set according to the ammonia introduction method.

[0090] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0091] The value range of the weighting coefficient Ki is inversely proportional to the value of i.

[0092] A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the present invention is characterized in that:

[0093] The matching setting of the corresponding response sensitivity described in step SS3 is to set the number of continuous rolls in the corresponding interval according to the corresponding response sensitivity requirements.

[0094] The present invention provides a method for controlling and adjusting the gas nitriding process of a continuous annealing steel coil.

[0095] First, a real-time nitrogen content monitoring of the steel coil is established through a set nitrogen content monitoring module, and a prediction is established for the steel coil to be produced after the production abnormality (i.e., the warning occurs) is generated according to the monitoring; wherein, the prediction is completed according to the set prediction model, and the real-time nitrogen content is completed according to the idea of ​​sampling and setting multiple collection points on the sample, then detecting each collection point, and then weighted averaging;

[0096] Secondly, by setting the deviation correction control model, the ammonia flow rate of the subsequent produced steel coils is set based on the prediction model, and the ammonia flow rate setting value is used as the actual ammonia value of the steel coil; the numerical value of the deviation correction control model is substituted into the linear fitting based on the least squares method, and it is concluded that with the advancement of the production process, the number of warnings generated increases, and the data in the sample space that can be provided to the least squares analysis gradually transitions from sparse to dense, which will gradually improve the accuracy of the fitting results.

[0097] In summary, the present invention is a method for controlling and adjusting the gas nitriding process of continuously annealed steel coils. Based on data integration and in accordance with the time series of the end of production, real-time nitrogen content detection is established for each steel coil. Through the set nitrogen content monitoring module and the set corresponding early warning rules, automatic monitoring of the nitriding process of the steel coils in the continuous production process is realized. When a skewed distribution appears in the nitriding process, a rapid response is made according to the set correction control model, and the nitriding process of the steel coils in production is accurately predicted and adjusted, which greatly shortens the process adjustment time and improves the stability of product quality. That is: First, abnormal situations such as skewed control and mean shift that may occur in the nitriding control process during production operation are discovered in time, thereby improving the timeliness of response in abnormal situations. Second, based on real-time detection and output of nitriding process parameters, and real-time analysis, the accuracy and pertinence of process adjustments are improved, and the level of process control capability is improved. Third, the dependence on personnel skills and response timeliness is eliminated, and labor efficiency is improved;

[0098] In addition, the technical structure and related models constructed by the present invention also provide a basic platform for future optimization. BRIEF DESCRIPTION OF THE DRAWINGS

[0099] Figure 1 It is a schematic diagram of the steps of the present invention;

[0100] Figure 2 A schematic diagram of the process of establishing the early warning rules in the present invention;

[0101] Figure 3 A schematic diagram of establishing a corresponding relationship over time series in the present invention;

[0102] Figure 4 It is a schematic diagram of the process of forming the deviation correction control model in the present invention;

[0103] Figure 5 This is a schematic diagram of the sample sampling position in the present invention;

[0104] Figure 6 It is a scatter plot of the standard conversion value and the predicted value of the actual ammonia flow rate in the embodiment of the present invention. DETAILED DESCRIPTION

[0105] Hereinafter, a method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to the accompanying drawings and specific implementation modes of the present invention will be further described in detail.

[0106] like Figure 1 A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil is shown, characterized in that: the control and adjustment method is specifically performed according to the following steps:

[0107] S1: Establish real-time detection of nitrogen content for each steel coil after nitriding.

[0108] S2: Establish real-time monitoring of the detection results according to the established nitrogen content monitoring module. When the monitoring results trigger the early warning of the nitrogen content monitoring module, enter step S3. Otherwise, monitor the real-time detection results of the nitrogen content of the next nitriding-finished steel coil according to the time sequence of the end of the production of the steel strip;

[0109] S3: Establishing a prediction of the nitrogen content of the next steel coil to be produced according to the established prediction model;

[0110] Among them, the prediction of the nitrogen content of the next steel coil to be produced in step S3 is characterized by the prediction model established for the ammonia flow rate of the next steel coil to be produced; after step S3, the ammonia flow rate setting of the next steel coil to be produced is also completed through the set correction control model.

[0111] in,

[0112] After step S3, the nitrogen content of the next steel coil to be produced is set by using the set deviation correction control model.

[0113] in,

[0114] The completed set value for the nitrogen content of the next steel coil to be produced is recorded as its actual value.

[0115] in,

[0116] Step S1 is specifically as follows:

[0117] Take the width of the steel coil as the length, cut a section along the length of the steel coil as the width, and form a rectangular sample.

[0118] By using a measuring instrument based on the inert gas melting principle, a total nitrogen content test is established for the sample to form a characterization of the total nitrogen content of the steel coil.

[0119] in,

[0120] The warning described in step S2 is mapped by the set warning rules, and when the monitoring result meets any rule in the warning rules, the warning is triggered;

[0121] The warning rules described above, such as Figure 2 As shown, follow the steps below to determine:

[0122] SS1: Based on the target requirements and allowable tolerance of total nitrogen content, a nitrogen content monitoring closed interval is formed for the same steel grade;

[0123] SS2: According to the control target and range requirements of the product process for nitrogen content, the nitrogen content monitoring closed interval is divided into intervals to form an early warning interval;

[0124] SS3: According to the response sensitivity requirements of the target value of total nitrogen content, the upper limit of the nitrogen monitoring closed interval, and the lower limit of the nitrogen monitoring closed interval, the corresponding response sensitivity is matched and set for each warning interval.

[0125] in,

[0126] The time series of the end of the production of the steel coil described in step S2 is as follows: Figure 3 As shown, follow the steps below to determine:

[0127] SF1: The process computer receives the unit inlet width, thickness, and ammonia flow rate of the steel coil sent by the basic automation control machine in real time; and records the real-time detection value of the nitrogen content of each steel coil completed based on step S1 in real time;

[0128] SF2: The process computer establishes the nitriding process steel coil number according to the steel coil production end time sequence;

[0129] SF3: The process computer establishes a one-to-one correspondence between the nitriding process coil number, the unit inlet width, thickness, ammonia flow rate of each coil, and the nitrogen content detection value of each coil, forming a time series containing the above information.

[0130] in,

[0131] The warning described in step S2 is mapped by the set warning rules, and when the monitoring result meets any rule in the warning rules, the warning is triggered;

[0132] The warning rules described above, such as Figure 3 As shown, follow the steps below to determine:

[0133] SS1: Based on the target requirements and allowable tolerance of total nitrogen content, a nitrogen content monitoring closed interval is formed for the same steel grade;

[0134] SS2: According to the control target and range requirements of the product process for nitrogen content, the nitrogen content monitoring closed interval is divided into intervals to form an early warning interval;

[0135] SS3: According to the target value of total nitrogen content, the upper limit of nitrogen content monitoring closed interval, and the response sensitivity requirements of the lower limit of nitrogen content monitoring closed interval, the number of continuous rolls in the corresponding interval is set;

[0136] The prediction of the nitrogen content of the next steel coil to be produced in step S3 is characterized by the prediction of the ammonia flow rate of the next steel coil to be produced established by the prediction model. The prediction of the ammonia flow rate is specifically as follows:

[0137]

[0138] in,

[0139] Fy: predicted flow rate of ammonia, unit: m 3 / h;

[0140] Ki: weighting coefficient;

[0141] Fi: Actual value of ammonia flow rate in volume i, unit: m 3 / h;

[0142] X: process target value of total nitrogen content in product; unit: ppm;

[0143] Ti: The total nitrogen content of each steel coil under the corresponding warning rule for this warning, unit: ppm;

[0144] Hi: the thickness of the roll, unit: mm;

[0145] Wi: the width of the roll, unit: mm;

[0146] H: predicted thickness of the steel coil, unit: mm;

[0147] W: predicted width of the steel coil, unit: mm;

[0148] m: the number of consecutive volumes corresponding to the corresponding warning rule.

[0149] Among them, Figure 4 As shown, the calculation of the deviation correction control model is performed according to the following steps:

[0150] SA1: The predicted value of ammonia flow rate completed according to the prediction model and the standard conversion value of the actual value of ammonia flow rate of the predicted volume are analyzed by the least square method to obtain the unknown number of linear fitting;

[0151] SA2: Substitute the predicted value of the ammonia flow rate and the value of the unknown variable obtained into the correction control model to calculate the ammonia flow set value for the next steel coil to be produced.

[0152] in,

[0153] The deviation correction control model is:

[0154] F=Fy.f+b,

[0155] in,

[0156] F: actual value of ammonia flow rate of the predicted volume; unit: m 3 / h;

[0157] Fy: predicted flow rate of ammonia, unit: m 3 / h;

[0158] f: ammonia adjustment factor corresponding to the warning rule;

[0159] b: The error constant corresponding to the warning rule.

[0160] in,

[0161] The standard conversion value of the actual value of the ammonia flow rate of the forecast volume, wherein the standard conversion value is specifically:

[0162]

[0163] in,

[0164] Fc: standard conversion value, unit: m 3 / h;

[0165] F: actual value of ammonia flow rate of the predicted volume, unit: m 3 / h;

[0166] X: target value of total nitrogen content in the predicted volume, unit: ppm;

[0167] T: actual value of total nitrogen content in the predicted volume, unit: ppm;

[0168] n: The number of warnings that occur under this warning rule.

[0169] in,

[0170] The "detection of the total nitrogen content of the sample" is completed by setting multiple detection points on the sample and then processing the multiple detection points based on the weighted average concept.

[0171] in,

[0172] The setting of multiple detection points on the template specifically includes: setting multiple detection points along the diagonal line of the template.

[0173] in,

[0174] The processing of multiple detection points based on the weighted average idea is completed as follows:

[0175]

[0176] in,

[0177] T: actual value of total nitrogen content of steel coil, unit: ppm;

[0178] Ci: Nitrogen content test result value at each test point, unit: ppm;

[0179] Zi: weighting coefficient.

[0180] in,

[0181] The weighting coefficient Zi is specifically set according to the ammonia introduction method.

[0182] in,

[0183] The value range of the weighting coefficient Ki is inversely proportional to the value of i.

[0184] in,

[0185] The matching setting of the corresponding response sensitivity described in step SS3 is to set the number of continuous rolls in the corresponding interval according to the corresponding response sensitivity requirements.

[0186] Working principle, working process and implementation examples

[0187] Step 1: Collect various production process parameter performance data through the basic automation control L1 system, including the unit inlet width W (unit mm), thickness H (unit mm), and ammonia flow data (unit m3 / h) of the steel coil. The data collected by the L1 system are transmitted to the process control L2 system.

[0188] Step 2: Take a rectangular sample from the strip steel after nitriding and take several small samples on the diagonal of the sample to test the nitrogen content. The nitrogen content is measured by a measuring instrument based on but not limited to the principle of inert gas fusion method. The test results of each point are weighted averaged. The weighted formula is: Where T is the total nitrogen content of the strip (in ppm), n is the number of sampling points, Ci is the nitrogen content test result of each point (in ppm), Zi≤1 and Preferably, the weighted coefficient Zi of each detection point is related to the ammonia introduction method adopted. If ammonia is introduced on both sides of the strip, the weighted coefficient Zi of the detection point close to the middle of the strip is 0.3-0.9. If ammonia is introduced on the top and bottom of the strip, the weighted coefficient Zi of the point close to the middle of the strip is 0.1-0.5. The value of T is also uploaded to the process control L2 system.

[0189] Step 3: In the process control system L2, according to the end time sequence of steel coil production, the steel coil number of the nitriding process is established, and it is combined and synthesized with the above data to complete the construction of a data warehouse containing all characteristic data.

[0190] Step 4: Establish nitrogen content monitoring rules. For the same steel type, according to the target control range of the total nitrogen content, use the control target value X, control tolerance W, and divide the warning interval according to the requirements of the production line for product control, such as X~X+W / 2, X+W / 2~X+W, X~XW / 2, XW / 2~XW four intervals, or X~X+W / 3, X+W / 3~X+W, X~XW / 2, XW / 2~XW, four intervals) to divide several warning intervals. In the L2 system, according to the end time of each steel coil production, establish the time series of the total nitrogen content T of each steel coil. During the time lapse, set different warning rules according to the distribution of the total nitrogen content T of each coil of continuous m coils in different intervals. In a certain interval, the fewer the number of distribution coils set for the warning, the stronger the model sensitivity. In the interval close to the upper and lower control limits (according to the above example, the response requirement in the interval X+W / 2~X+W is more sensitive than that in X~X+W / 2, because the closer to the upper and lower limits, the more likely it is to exceed the upper and lower limits, so it must be more sensitive), the model should be more sensitive, and the requirements for the number of continuously distributed steel coils should be more stringent. The closer the interval is to the control target, the more relaxed the requirements for the number of continuously distributed steel coils can be.

[0191] Step 5: Based on the steel coils under the same warning rule, and the total nitrogen content and related characteristic parameters of all steel coils that generate warnings each time, calculate the predicted ammonia flow rate Fy of the production coil after the warning occurs. The specific method is: Ammonia predicted flow rate in Where Fy is the predicted ammonia flow rate, H is the predicted thickness of the steel coil, W is the predicted width of the steel coil, X is the total nitrogen content target, Ti is the total nitrogen content of the steel coil that generates the warning and is the i-th coil in the production sequence of the predicted steel coil (according to the production time sequence, the i-th coil closest to the predicted steel coil is 1, and the i-th coil before that is 2, counting down in time sequence), Fi is the actual ammonia flow rate performance value of the coil, Hi is the thickness of the coil, Wi is the width of the coil, Ki≤1 and is the weighting coefficient. Preferably, the smaller i is, the larger the value of Ki should be. When i is between 1 and 2, Ki is 0.3-0.7, and when i ≥ 2, Ki is 0.1-0.5. Because the smaller i is, the closer the production time of the roll is to the predicted roll, and the greater the impact on the prediction, the larger Ki can be.

[0192] Step 6: Calculate the ammonia flow adjustment coefficient. Use the least squares method to analyze the predicted ammonia flow Fy and the standard conversion value of the actual ammonia flow F of the production volume after the warning. The fitting formula is: Where X is the total nitrogen content target, and T is the average total nitrogen content of all steel coils to be predicted under this type of early warning rule. The value of the ammonia adjustment coefficient f and the error constant b under each early warning rule are obtained and stored in the corresponding storage space of the L2 system.

[0193] Step 7: During normal production, the L2 system receives the total nitrogen content result of each steel coil, combines the total nitrogen content result of the coil with that of the previous steel coil for judgment, and when an early warning occurs according to the early warning rule, calls up the calculation model and parameters of the corresponding early warning rule, calculates the ammonia flow setting value according to the formula F=Fy*f+b, and sets the ammonia flow of the predicted coil according to this value. At the same time, the relevant data obtained under the flow setting is included in the sample space for least squares analysis as a sample, and the process of steps 5 and 6 is repeated to update the values ​​of the ammonia adjustment coefficient f and the error constant b.

[0194] In the above, it is particularly important to point out that when the first warning occurs, F is Fy.

[0195] According to the above embodiment, the details are as follows:

[0196] When the technical solution of this case is actually used, it is assumed that several values ​​corresponding to the warnings have been collected; the unit inlet width W (unit mm), thickness H (unit mm), and ammonia flow data (unit m3 / h) of the steel coil are collected through the L1 system of the unit and transmitted to the process control L2 system to build the training set data of the data warehouse. For this type of steel product, the target control range of the total nitrogen content is 100±50 (ppm).

[0197] The total nitrogen content of each coil is tested and calculated by taking a rectangular sample and taking 5 small samples on the diagonal of the sample to test the nitrogen content. The sampling positions are as follows: Figure 5 shown.

[0198] Each sample is measured using a nitrogen analyzer based on the inert gas fusion method. The measurement results, weighted coefficients of each sample and calculation rules for the total nitrogen content are shown in Table 1. The total nitrogen content value is uploaded to the L2 system.

[0199] Table 1

[0200]

[0201] The nitrogen content monitoring rules for this steel grade are shown in Table 2:

[0202] Table 2

[0203]

[0204] All warning situations within a certain period of time are selected as the situation with sequence number 1 as the training set data training. The data set is shown in Table 3:

[0205] Table 3

[0206]

[0207]

[0208] The predicted ammonia flow value and the standard conversion value of the actual ammonia flow of the production volume after the warning are analyzed by the least squares method, see Table 4

[0209] Table 4

[0210]

[0211] The fitting results are as follows: standard conversion value = -0.6 + 1.20Fy, and the value of the ammonia adjustment coefficient f under the early warning rule is 1.20 and the value of the error constant b is -0.6.

[0212] According to the above method, the value of the ammonia adjustment coefficient f and the value of the error constant b in the warning situations of sequence numbers 2 and 3 are obtained respectively, and stored in the corresponding storage space of the L2 system.

[0213] During a normal production, the L2 system received the following total nitrogen content results of the steel coil, see Table 6.

[0214] Table 6

[0215]

[0216] It is judged as the case of warning rule number 1, and the calculation model and parameters of the corresponding warning rule are retrieved. The ammonia flow value F is calculated according to the formula F = -0.6 + 1.20Fy, and the ammonia flow of the predicted volume is set according to the F value. The total nitrogen content of the predicted volume is finally detected to be 98ppm, see Table 7

[0217] Table 7

[0218]

[0219] At the same time, the relevant result data of the volume is incorporated into the same type of early warning rule data set in the training set, that is, Table 4 is updated, see Table 8, and according to steps five and six, the new regression equation is obtained:

[0220] F=-0.34+1.07Fy, update the value of ammonia adjustment coefficient f and error constant b.

[0221] Table 8

[0222]

[0223] The present invention provides a method for controlling and adjusting the gas nitriding process of a continuous annealing steel coil.

[0224] First, a real-time nitrogen content monitoring of the steel coil is established through a set nitrogen content monitoring module, and a prediction is established for the steel coil to be produced after the production abnormality (i.e., the warning occurs) is generated according to the monitoring; wherein, the prediction is completed according to the set prediction model, and the real-time nitrogen content is completed according to the idea of ​​sampling and setting multiple collection points on the sample, then detecting each collection point, and then weighted averaging;

[0225] Secondly, by setting the deviation correction control model, the ammonia flow rate of the subsequent produced steel coils is set based on the prediction model, and the ammonia flow rate setting value is used as the actual ammonia value of the steel coil; the numerical value of the deviation correction control model is substituted into the linear fitting based on the least squares method, and it is concluded that with the advancement of the production process, the number of warnings generated increases, and the data in the sample space that can be provided to the least squares analysis gradually transitions from sparse to dense, which will gradually improve the accuracy of the fitting results.

[0226] In summary, the present invention is a method for controlling and adjusting the gas nitriding process of continuously annealed steel coils. Based on data integration and in accordance with the time series of the end of production, real-time nitrogen content detection is established for each steel coil. Through the set nitrogen content monitoring module and the set corresponding early warning rules, automatic monitoring of the nitriding process of the steel coils in the continuous production process is realized. When a skewed distribution appears in the nitriding process, a rapid response is made according to the set correction control model, and the nitriding process of the steel coils in production is accurately predicted and adjusted, which greatly shortens the process adjustment time and improves the stability of product quality. That is: First, abnormal situations such as skewed control and mean shift that may occur in the nitriding control process during production operation are discovered in time, thereby improving the timeliness of response in abnormal situations. Second, based on real-time detection and output of nitriding process parameters, and real-time analysis, the accuracy and pertinence of process adjustments are improved, and the level of process control capability is improved. Third, the dependence on personnel skills and response timeliness is eliminated, and labor efficiency is improved;

[0227] In addition, the technical structure and related models constructed by the present invention also provide a basic platform for future optimization.

Claims

1. A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil, characterized in that: The control and adjustment method is specifically performed according to the following steps: S1: Establish real-time detection of nitrogen content for each steel coil after nitriding, specifically: The width of the steel coil is taken as the length, and a section is cut along the length direction of the steel coil as the width to form a rectangular sample. A measuring instrument based on the inert gas melting principle is used to establish a total nitrogen content detection for the sample to form a characterization of the total nitrogen content of the steel coil. The total nitrogen content detection of the sample is completed by setting multiple detection points on the sample and then processing the multiple detection points based on the weighted average idea. The processing of multiple detection points based on the weighted average idea is completed as follows: in, T: actual value of total nitrogen content of steel coil, unit: ppm; Ci: Nitrogen content test result value at each test point, unit: ppm; Zi: weighting coefficient, n: the number of warnings that occur under this warning rule, S2: Establish real-time monitoring of the detection results according to the established nitrogen content monitoring module. When the monitoring results trigger the early warning of the nitrogen content monitoring module, enter step S3. Otherwise, monitor the real-time detection results of the nitrogen content of the next nitriding-finished steel coil according to the time sequence of the end of the production of the steel strip; The warning described in step S2 is mapped by the set warning rules, and when the monitoring result meets any rule in the warning rules, the warning is triggered; The warning rules are determined according to the following steps: SS1: Based on the target requirements and allowable tolerance of total nitrogen content, a nitrogen content monitoring closed interval is formed for the same steel grade; SS2: According to the control target and range requirements of the product process for nitrogen content, the nitrogen content monitoring closed interval is divided into intervals to form an early warning interval; SS3: According to the target value of total nitrogen content, the upper limit of nitrogen content monitoring closed interval, and the response sensitivity requirements of the lower limit of nitrogen content monitoring closed interval, the number of continuous rolls in the corresponding interval is set; S3: Establishing a prediction of the nitrogen content of the next steel coil to be produced according to the established prediction model, that is, establishing a prediction representation of the ammonia flow rate of the next steel coil to be produced through the prediction model, After step S3, the set deviation correction control model is used to set the ammonia flow rate of the next steel coil to be produced. The set value for the nitrogen content of the next steel coil to be produced is recorded as its actual value. The details include: SA1: The predicted value of ammonia flow rate completed according to the prediction model and the standard conversion value of the actual value of ammonia flow rate of the prediction volume are analyzed by the least square method to obtain the unknown number of linear fitting; SA2: Substitute the predicted value of ammonia flow rate and the value of the unknown variable into the deviation correction control model to calculate the set value of ammonia flow rate for the next steel coil to be produced. The deviation correction control model is: F=Fy.f+b, in, F: actual value of ammonia flow rate of the predicted volume; unit: m 3 / h; Fy: predicted flow rate of ammonia, unit: m 3 / h; f: ammonia adjustment factor corresponding to the warning rule; b: The error constant corresponding to the warning rule, The standard conversion value of the actual value of the ammonia flow rate of the forecast volume, wherein the standard conversion value is specifically: in, Fc: standard conversion value, unit: m 3 / h; F: actual value of ammonia flow rate of the predicted volume, unit: m 3 / h; X: target value of total nitrogen content in the predicted volume, unit: ppm; T: actual value of total nitrogen content in the predicted volume, unit: ppm; The time series of the end of the production of the steel coil described in step S2 is determined according to the following steps: SF1: The process computer receives the unit inlet width, thickness, and ammonia flow rate of the steel coil sent by the basic automation control machine in real time; and records the real-time detection value of the nitrogen content of each steel coil completed based on step S1 in real time; SF2: The process computer establishes the nitriding process steel coil number according to the steel coil production end time sequence; SF3: The process computer establishes a one-to-one correspondence between the nitriding process coil number, the unit inlet width, thickness, ammonia flow rate of each coil, and the nitrogen content detection value of each coil, forming a time series containing the above information. The prediction of the nitrogen content of the next steel coil to be produced in step S3 is characterized by the prediction of the ammonia flow rate of the next steel coil to be produced established by the prediction model. The prediction of the ammonia flow rate is specifically as follows: in, Fy: predicted flow rate of ammonia, unit: m 3 / h; Ki: weighting coefficient; Fi: Actual value of ammonia flow rate in volume i, unit: m 3 / h; X: process target value of total nitrogen content in product; unit: ppm; Ti: The total nitrogen content of each steel coil under the corresponding warning rule for this warning, unit: ppm; Hi: the thickness of the roll, unit: mm; Wi: the width of the roll, unit: mm; H: predicted thickness of the steel coil, unit: mm; W: predicted width of the steel coil, unit: mm; m: the number of consecutive volumes corresponding to the corresponding warning rule.

2. A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to claim 1, characterized in that: The warning described in step S2 is mapped by the set warning rules, and when the monitoring result meets any rule in the warning rules, the warning is triggered; The warning rules are determined according to the following steps: SS1: Based on the target requirements and allowable tolerance of total nitrogen content, a nitrogen content monitoring closed interval is formed for the same steel grade; SS2: According to the control target and range requirements of the product process for nitrogen content, the nitrogen content monitoring closed interval is divided into intervals to form an early warning interval; SS3: According to the response sensitivity requirements of the target value of total nitrogen content, the upper limit of the nitrogen monitoring closed interval, and the lower limit of the nitrogen monitoring closed interval, the corresponding response sensitivity is matched and set for each warning interval.

3. A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to claim 1, characterized in that: The setting of multiple detection points on the template specifically includes: setting multiple detection points along the diagonal line of the template.

4. A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to claim 1, characterized in that: The weighting coefficient Zi is specifically set according to the ammonia introduction method.

5. A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to claim 1, characterized in that: The value range of the weighting coefficient Ki is inversely proportional to the value of i.

6. A method for controlling and adjusting the gas nitriding process of a continuously annealed steel coil according to claim 2, characterized in that: The matching setting of the corresponding response sensitivity described in step SS3 is to set the number of continuous rolls in the corresponding interval according to the corresponding response sensitivity requirements.

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