A method for setting the shape quality of incoming plates for the purpose of achieving continuous annealing stable strip

Abstract

The present application belongs to the technical field of metallurgical rolling, and particularly relates to a kind of incoming plate shape quality setting method with continuous annealing stable plate as target, key equipment characteristic parameters and process parameters of continuous annealing unit are collected;Define related parameters and define the objective function equation of incoming plate shape of continuous annealing unit;The transverse compressive stress suffered by the local strip is calculated by calculating the poisson stress and thermal stress affecting the width direction of the strip;The critical buckling index of the i section of the strip is calculated from the transverse compressive stress of the strip and the critical instability force of the strip;The initial solution of the incoming plate shape target curve equation is set by calculating the running deviation factor and optimizing the parameters of the tension difference in the width direction of the strip;Establish the comprehensive optimization objective function of controlling the incoming plate shape of continuous annealing;Judge the comprehensive objective function of incoming plate shape of continuous annealing;Output the optimal solution.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical steel rolling technology, and specifically relates to a method for setting the shape and quality of incoming material with the goal of stabilizing the continuous annealing of the plate. Background Technology

[0002] Strip shape, as one of the quality indicators of cold-rolled strip steel, has received increasing attention. Strip shape essentially refers to the transverse distribution of residual stress within the strip. If tensile stress redistributes laterally, localized plastic deformation occurs in the strip. This change in strip shape will not only affect the current unit but also the strip shape at the unit's exit and even the finished strip shape. Furthermore, the strip shape within and at the unit's exit differs. The strip shape within a unit is the result of the superposition of the incoming strip shape from the pickling and rolling mill and the strip shape caused by unevenness in the continuous annealing furnace. The strip shape at the unit's exit is the result of the superposition of both the incoming strip shape from the pickling and rolling mill and the strip shape caused by localized plastic deformation in the continuous annealing furnace. The exit strip shape of the continuous annealing unit is the same as the inlet strip shape of the leveling unit, and its quality directly affects the quality of the finished strip shape.

[0003] Previous research on continuous annealing processes has mainly focused on product performance and strip stability, while also using the cold-rolled exit strip shape as the entry strip shape for continuous annealing flattening, neglecting the impact of the continuous annealing process on the strip shape. This has led to quality problems with the finished strip shape. Therefore, this study develops a method for setting the incoming strip shape quality of continuous annealing with the goal of stabilizing the strip flow of the continuous annealing unit. This method enables control over the incoming strip shape of the continuous annealing unit, thereby better ensuring the strip shape quality of the finished strip. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, the technical problem solved by this invention is to provide a method for setting the incoming strip shape quality with the goal of stabilizing the continuous annealing process. Specifically, during the continuous annealing of strip steel, a high-order polynomial function is set as the incoming strip shape at the annealing inlet. Based on the fact that strip steel is prone to deviation and warping due to stress during continuous annealing, a calculation model for the strip deviation factor and warping index during continuous annealing is established. Combining the influence of the incoming strip shape, and with the goal of stabilizing the continuous annealing unit, a comprehensive optimization objective function for the incoming strip shape during the continuous annealing process is established, thus completing the setting of the incoming strip shape quality for continuous annealing.

[0005] To achieve the above objectives, the present invention employs the following technical solution:

[0006] A method for setting the shape and quality of incoming sheet metal with the goal of stabilizing continuous annealing of the sheet metal includes the following steps:

[0007] (a) Collect key equipment characteristic parameters of the continuous annealing unit, mainly including: furnace roll radius R, mm, and length of the straight section of the furnace roll. mm, furnace roll taper rad, critical taper of furnace roll rad, unit speed V, m / s, coefficient of friction between strip and furnace rolls ;

[0008] (b) Collect rolling process parameters, mainly including: strip entry thickness mm, strip width B, mm, strip Poisson's ratio v, strip critical curvature index Critical deviation factor of strip steel ;

[0009] (c) Define relevant parameters, mainly including: process segmentation along the strip width direction, with a total number of segments of 2n+1, where i is a segment number, and i takes the value 1, 2, 3…2n+1; and the strip deviation factor for the i-th segment. The i-th segment of the steel plate bending index The objective function for comprehensive optimization of incoming material plate shape is G(X), the weighting coefficient is A, and the Poisson's ratio is v.

[0010] (d) Define the objective function equation for the incoming plate shape of the continuous annealing unit, as follows:

[0011] (1)

[0012] In the formula, the coefficients of each term The variable to be determined; The parameters are for the iteration process; j takes values ​​of 1, 2, 3…m; x is the coordinate value of the centerline of each strip steel element. ;

[0013] (e) By calculating the Poisson stress affecting the width direction of the strip. Thermal stress To calculate the transverse compressive stress in the local area of ​​the strip. :

[0014] Poisson stress The formula is:

[0015] (2)

[0016] In the formula: Poisson stress, MPa; The tension of the strip at point x within the (i-1)th process segment, in MPa; The tension of the strip at point x within the i-th process segment, in MPa; R is Poisson's ratio; R is the radius of the furnace roll, mm; L is the length of the furnace roll body, mm;

[0017] thermal stress As shown in equation (3):

[0018] (3)

[0019] In the formula: Thermal stress, MPa; The stress range is in mm. E is the coefficient of linear expansion of the strip; E is the elastic modulus, in MPa. The value represents the temperature change of the strip, in °C.

[0020] Sliding friction and centripetal force The formula is as follows:

[0021] (4)

[0022] In the formula: The sliding friction force experienced by the strip during lateral movement in the unstable region, in MPa; The coefficient of friction; The centripetal force acting on the unstable region of the strip, in MPa; The velocity of the through-plate is m / s; k is the velocity influence coefficient. The taper of the furnace rollers is expressed in rad. denoted as Critical taper angle of the furnace roll (rad); S is the length of the straight section of the furnace roll (mm); b is the width of the strip instability zone (mm).

[0023] Calculate the transverse compressive stress in the width direction of the strip. :

[0024] when When the transverse compressive stress in a local area of ​​the strip is expressed as: ;when When the strip shrinks in a localized area, the centripetal force generated by the rotation of the furnace rolls becomes the dominant driving force, and the transverse compressive stress is expressed as... ;

[0025] (f) When the strip is in a critical instability state, the critical instability stress of the strip is calculated using the following formula:

[0026] (5)

[0027] (g) The critical buckling index of the i-th segment of the strip is calculated from the transverse compressive stress and the critical buckling force of the strip, using the following formula:

[0028] (6)

[0029] (h) The deviation factor is calculated using the tension difference in the strip width direction, as shown in the following formula:

[0030] (7)

[0031] In the formula: Let be the deviation factor for the i-th segment; The tension distribution along the width of the strip is given in MPa. The velocity of the through-plate is m / s; k is the velocity influence coefficient. These are the model coefficients; This refers to the strip misalignment, expressed in mm. The coefficient of friction between the strip steel and the furnace roll; Friction influence coefficient;

[0032] (i) Set the optimization parameter s, let s=0, set the optimization step size Δk, and the iteration precision. The initial solution of the target curve equation for the incoming material plate shape ;

[0033] (j) Let , ;

[0034] (k) Establish the comprehensive optimization objective function for controlling the shape of the incoming material plate during continuous retraction, as shown in the following formula:

[0035] (8)

[0036] In the formula: This is the export plate shape control function; For the control function of the strip steel stabilization plate; For continuous annealing of incoming material plate shape; A, These are weighting coefficients; This represents the maximum value of the continuous retraction inlet plate shape;

[0037] (l) Given constraints:

[0038] (9)

[0039] (m) Determine the comprehensive objective function for the shape of the continuously annealed incoming material plate. Is it true? If not, let If yes, proceed to step (j); otherwise, proceed to step (n).

[0040] (n) Output the optimal solution Substituting the equation of the incoming material target curve, we obtain the incoming material shape target curve that satisfies the continuous annealing finished product shape condition.

[0041] The optimization step size Iteration accuracy =0.001.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] This invention sets the incoming strip shape at the continuous annealing inlet as a high-order polynomial function. Based on the fact that strip steel is prone to deviation and warping due to stress during continuous annealing, a calculation model for the strip deviation factor and warping index during continuous annealing is established. Combining the influence of the incoming strip shape, and with the goal of stable strip flow of the continuous annealing unit, a comprehensive optimization objective function for the incoming strip shape during continuous annealing is established. This completes the setting of the incoming strip shape quality for continuous annealing, realizes the control of the incoming strip shape of the continuous annealing unit, and further ensures the strip shape quality of the finished strip steel. Attached Figure Description

[0044] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0045] Figure 1 This is a flowchart for setting the quality of incoming sheet material with the goal of stabilizing the continuous annealing process.

[0046] Figure 2 It is the material plate shape distribution value of the continuous annealing unit in Example 1.

[0047] Figure 3 This is the material plate shape distribution value of the continuous annealing unit in Example 2. Detailed Implementation

[0048] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0049] Example 1:

[0050] like Figure 1 As shown, taking a certain continuous annealing unit as an example, the method for setting the shape and quality of incoming material with the goal of stabilizing the continuous annealing plate described in this invention will be explained in detail.

[0051] Taking HC340LA steel with a specification of 1.2mm×1200mm as an example, the calculation is performed.

[0052] (a) Collect key equipment characteristic parameters of the continuous annealing unit, mainly including: furnace roll radius R=450mm, furnace roll straight section length furnace roller taper =0.003rad, critical taper =0.004rad, unit speed V=6m / s, coefficient of friction between strip and furnace rolls =0.15;

[0053] (b) Collect rolling process parameters, mainly including: strip entry thickness =1.2mm, strip width B=1200mm, strip Poisson's ratio v=0.31, strip critical curvature index =1.0, critical deviation factor for strip steel =100;

[0054] (c) Define relevant parameters, mainly including: process segmentation along the strip width direction, with a total of 21 segments, where i is a segment number, with i taking values ​​of 1, 2, 3…21, and the strip deviation factor for the i-th segment. The i-th segment of the steel plate bending index The objective function for comprehensive optimization of incoming material plate shape is G(X), the weighting coefficient is A, and the Poisson's ratio is v.

[0055] (d) Define the objective function equation for the incoming plate shape of the continuous annealing unit:

[0056]

[0057] In the formula, the coefficients of each term The variable to be determined; Here are the parameters for the iteration process; j takes values ​​of 1, 2, 3…m; x is the length of the segment based on the strip width direction. ;

[0058] (e) Calculate the Poisson stress that affects the transverse compressive stress using formula (2). ={12.18,11.69,11.43,11.39,11.62,12.11,12.87,13.93,15.29,16.97,17.70,18.41,19.10,19.80,20.50,21.22,21.94,22.69,23.47,24.26,25.07}MPa; Calculate the thermal stress using formula (3). =60.99MPa, thus obtaining The sliding friction force is calculated using formula (4). and centripetal force The calculation results are as follows:

[0059] ={2.18,2.09,2.04,2.04,2.07,2.16,2.29,2.49,2.73,3.03,3.16,3.29,3.41,3.54,3.66,3.79,3.92,4.05,4.19,4.33,4.48}MPa;

[0060] ={17.32,16.63,16.25,16.21,16.52,17.21,18.31,19.81,21.75,24.14,25.1 8,26.19,27.18,28.17,29.16,30.18,31.21,32.28,33.38,34.50,36.65}MPa;

[0061] Therefore, the transverse compressive stress on the local area of ​​the strip can be calculated. The calculation results are as follows:

[0062] ={19.50,18.72,18.29,18.24,18.60,19.37,20.61,22.30,24.49,27.17,28.3 4,29.48,30.59,31.70,32.82,33.96,35.13,36.33,37.57,38.83,40.13}MPa;

[0063] (f) Calculate the critical instability stress of the strip when it is in a critical instability state using formula (5). =48.91MPa;

[0064] (g) Calculate the flexural index of the strip using formula (6): ={0.35,0.38,0.37,0.37,0.38,0.40,0.42,0.46,0.50,0.56,0.58,0.60,0.63,0.65,0.67,0.69,0.72,0.74,0.77,0.79,0.82};

[0065] (h) Calculate the deviation factor using formula (7): ={21.93,21.05,20.57,20.51,20.91,21.79,23.17,25.08,27.53,30.55,31.86,33.14,34.39,35.64,36.90,38.18,39.50,40.85,42.24,43.66,45.11};

[0066] (i) Set the optimization parameter s, let s=0, and set the optimization step size. Iteration accuracy =0.001, the initial solution of the target curve equation for the incoming material plate shape. ;

[0067] (j) Let , ;

[0068] (k) Establish a comprehensive optimization objective function for controlling the shape of the incoming material plate during continuous retraction. ;

[0069] (l) Set the critical tortuosity index Critical deviation factor Given the following constraints:

[0070]

[0071] (m) Determine the comprehensive objective function for the shape of the continuously annealed incoming material plate. Is it true? If not, let If yes, proceed to step (j); otherwise, proceed to step (n).

[0072] (n) Output the coefficients of the incoming material plate shape curve function. See the diagram for the material plate shape distribution of the continuous annealing unit. Figure 2 .

[0073] Example 2:

[0074] Taking CR260 / 450DP steel with a specification of 1.6mm×1200mm as an example, the calculation is performed.

[0075] (a) Collect key equipment characteristic parameters of the continuous annealing unit, mainly including: furnace roll radius R=450mm, furnace roll straight section length furnace roller taper =0.003rad, critical taper =0.004rad, unit speed V=0.9m / s, coefficient of friction between strip and furnace rolls =0.15;

[0076] (b) Collect rolling process parameters, mainly including: strip entry thickness =1.6mm, strip width B=1550mm, strip Poisson's ratio v=0.31, strip critical curvature index =1.0, critical deviation factor for strip steel =100;

[0077] (c) Define relevant parameters, mainly including: process segmentation along the strip width direction, with a total of 21 segments, where i is a segment number, with i taking values ​​of 1, 2, 3…21, and the strip deviation factor for the i-th segment. The i-th segment of the steel plate bending index The objective function for comprehensive optimization of incoming material plate shape is G(X), the weighting coefficient is A, and the Poisson's ratio is v.

[0078] (d) Define the objective function equation for the incoming plate shape of the continuous annealing unit:

[0079]

[0080] In the formula, the coefficients of each term The variable to be determined; Here are the parameters for the iteration process; j takes values ​​of 1, 2, 3…m; x is the length of the segment based on the strip width direction. ;

[0081] (e) Calculate the Poisson stress that affects the transverse compressive stress using formula (2). ={12.18,11.70,11.43,11.40,11.62,12.11,12.87,13.93,15.30,16.97,17.70,18.41,19.11,19.80,20.50,21.22,21.95,22.70,23.47,24.26,25.07} MPa, thermal stress =61.57MPa, thus obtaining The sliding friction force is calculated using formula (4). and centripetal force The calculation results are as follows:

[0082] ={3.26,3.13,3.06,3.05,3.11,3.24,3.45,3.73,4.10,4.55,4.74,4.93,5.12,5.30,5.49,5.68,5.88,6.08,6.29,6.50,6.71}MPa;

[0083] ={17.32,16.63,16.25,16.21,16.53,17.22,18.31,19.82,21.75,24.14,25.1 8,26.19,27.18,28.17,29.16,30.18,31.21,32.28,33.38,34.50,35.65}MPa;

[0084] Therefore, the transverse compressive stress on the local area of ​​the strip can be calculated. The calculation results are as follows:

[0085] ={20.58,19.76,19.31,19.26,19.64,20.46,21.76,25.55,25.85,28.68,29.9 2,31.12,32.29,33.47,34.65,35.86,37.09,38.36,39.66,41.00,42.37}MPa;

[0086] (f) Calculate the critical instability stress of the strip when it is in a critical instability state using formula (5). =86.96MPa;

[0087] (g) Calculate the tortuosity index using formula (6): ={0.23,0.23,0.22,0.22,0.23,0.24,0.25,0.27,0.30,0.33,0.34,0.36,0.37,0.38,0.40,0.41,0.43,0.44,0.46,0.47,0.48};

[0088] (h) Calculate the deviation factor using formula (7): ={17.61,16.91,16.52,16.48,16.80,17.51,18.62,20.15,22.12,24.54,25.60,26.63,27.63,28.64,29.65,30.68,31.74,32.82,33.94,35.08,36.25};

[0089] (i) Set the optimization parameter s, let s=0, and set the optimization step size. Iteration accuracy =0.001, the initial solution of the target curve equation for the incoming material plate shape. ;

[0090] (j) Let , ;

[0091] (k) Establish a comprehensive optimization objective function for controlling the shape of the incoming material plate during continuous retraction. ;

[0092] (l) Set the critical tortuosity index Critical deviation factor Given the following constraints:

[0093]

[0094] (m) Determine the comprehensive objective function for the shape of the continuously annealed incoming material plate. Is it true? If not, let If yes, proceed to step (j); otherwise, proceed to step (n).

[0095] (n) Output the coefficients of the incoming material plate shape curve function. See the diagram for the material plate shape distribution of the continuous annealing unit. Figure 3 .

[0096] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. In addition, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, and should also be considered as the content disclosed by the present invention.

Claims

1. A method for setting the shape and quality of incoming sheet metal with the goal of achieving continuous annealing and stabilization of the sheet metal, characterized in that, Includes the following steps: (a) Collect key equipment characteristic parameters of the continuous annealing unit, mainly including: furnace roll radius R, mm, and length of the straight section of the furnace roll. mm, furnace roll taper rad, critical taper of furnace roll rad, plate speed m / s, coefficient of friction between strip steel and furnace roll ; (b) Collect rolling process parameters, mainly including: strip entry thickness mm, strip width B, mm, strip Poisson's ratio Critical tortuosity index of strip steel Critical deviation factor of strip steel ; (c) Define relevant parameters, mainly including: process segmentation along the strip width direction, with a total number of segments of 2n+1, where i is a segment number, and i takes the value 1, 2, 3…2n+1; and the strip deviation factor for the i-th segment. The i-th segment of the steel plate bending index The objective function for comprehensive optimization of incoming material plate shape is G(X), the weighting coefficient is A, and the Poisson's ratio is... ; (d) Define the objective function equation for the incoming plate shape of the continuous annealing unit, as follows: （1） In the formula, the coefficients of each term The variable to be determined; The parameters are for the iteration process; j takes values ​​of 1, 2, 3…m; x is the coordinate value of the centerline of each strip steel element. ; (e) By calculating the Poisson stress affecting the width direction of the strip. Thermal stress To calculate the transverse compressive stress in the local area of ​​the strip. : Poisson stress The formula is: （2） In the formula: Poisson stress, MPa; The tension of the strip at point x within the (i-1)th process segment, in MPa; The tension of the strip at point x within the i-th process segment, in MPa; R is Poisson's ratio; R is the radius of the furnace roll, mm; L is the length of the furnace roll body, mm; thermal stress As shown in equation (3): （3） In the formula: Thermal stress, MPa; The stress range is in mm. E is the coefficient of linear expansion of the strip; E is the elastic modulus, in MPa. The value represents the temperature change of the strip, in °C. Sliding friction and centripetal force The formula is as follows: （4） In the formula: The sliding friction force experienced by the strip during lateral movement in the unstable region, in MPa; The coefficient of friction; The centripetal force acting on the unstable region of the strip, in MPa; The velocity of the through-plate is m / s; k is the velocity influence coefficient. The taper of the furnace rollers is expressed in rad. denoted as Critical taper angle of the furnace roll (rad); S is the length of the straight section of the furnace roll (mm); b is the width of the strip instability zone (mm). Calculate the transverse compressive stress in the width direction of the strip. : when When the transverse compressive stress in a local area of ​​the strip is expressed as: ;when When the strip shrinks in a localized area, the centripetal force generated by the rotation of the furnace rolls becomes the dominant driving force, and the transverse compressive stress is expressed as... ; (f) When the strip is in a critical instability state, the critical instability stress of the strip is calculated using the following formula: （5） (g) The critical buckling index of the i-th segment of the strip is calculated from the transverse compressive stress and the critical buckling force of the strip, using the following formula: （6） (h) The deviation factor is calculated using the tension difference in the strip width direction, as shown in the following formula: （7） In the formula: Let be the deviation factor for the i-th segment; The tension distribution along the width of the strip is given in MPa. The velocity of the through-plate is m / s; k is the velocity influence coefficient. These are the model coefficients; This refers to the strip misalignment, expressed in mm. The coefficient of friction between the strip steel and the furnace roll; Friction influence coefficient; (i) Set the optimization parameter s, let s=0, set the optimization step size Δk, and the iteration precision. The initial solution of the target curve equation for the incoming material plate shape ; (j) Let , ; (k) Establish the comprehensive optimization objective function for controlling the shape of the incoming material plate during continuous retraction, as shown in the following formula: （8） In the formula: This is the export plate shape control function; For the control function of the strip steel stabilization plate; For continuous annealing of incoming material plate shape; A, These are weighting coefficients; This represents the maximum value of the continuous retraction inlet plate shape; (l) Given constraints: （9） (m) Determine the comprehensive objective function for the shape of the continuously annealed incoming material plate. Is it true? If not, let If yes, proceed to step (j); otherwise, proceed to step (n). (n) Output the optimal solution Substituting the equation of the incoming material target curve, we obtain the incoming material shape target curve that satisfies the continuous annealing finished product shape condition.

2. The method for setting the incoming plate shape quality with the goal of continuously annealing and stabilizing the plate, as described in claim 1, is characterized in that... The optimization step size Iteration accuracy =0.001.

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