A method for optimizing the concentration and temperature of emulsion in a six-stand cold rolling mill

Abstract

The present invention discloses a method for optimizing the setting of the concentration and temperature of an emulsion of a six-stand cold rolling mill. The present invention fully considers the problem of slippage during the rolling process of ultra-high-strength steel, and combines the characteristics of the three oil tanks of the emulsion system of the unit participating in lubrication, that is, 1-3 frames share one oil tank, 4 frames have a separate oil tank, and 5 frames and 6 frames share one oil tank; the present invention fully considers the influence of the concentration of the emulsion and the initial temperature on the stable rolling of the strip during the cold rolling process, and takes the slip factor parameter as a constraint condition, and proposes a method for optimizing the setting of the concentration and temperature of the emulsion of a six-stand cold rolling mill with the oil film thickness control on the upper and lower surfaces of the strip as the target, thereby determining the optimal concentration and temperature of the emulsion, and improving the actual production efficiency and quality. Through the application of the present invention, the concentration and temperature optimization of the emulsion under the condition of multiple oil tanks are realized, the slippage phenomenon is reduced, the stability of the unit is guaranteed, the quality of the strip shape is improved, and certain economic benefits are brought.

Description

Technical Field

[0001] The invention belongs to the technical field of cold rolling, and in particular relates to an emulsion concentration and temperature optimization setting method suitable for a six-stand cold rolling unit with the goal of stable rolling. Background Art

[0002] In recent years, in response to the energy conservation and emission reduction policy, automobile lightweighting has become an important development trend. Automobile manufacturers have also put forward higher requirements for the product characteristics and quality of steel. Ultra-high strength steel is favored by the automobile, packaging and other manufacturing industries due to its excellent performance. A domestic steel plant has newly built a six-stand cold rolling unit as a professional ultra-high strength steel production unit, which has improved the rolling efficiency and production capacity of ultra-high strength steel. However, since the six-stand unit uses the emulsion concentration and temperature settings of the previous five-stand unit in production, it is not targeted, the field application is not ideal, and the six-stand unit is prone to slipping during the rolling process, which seriously affects the rolling stability of the strip products and the quality of the final product. When the six stands of the six-stand unit are working at the same time, three oil tanks participate in lubrication, which is different from the previous single oil tank lubrication effect. Therefore, through a large number of field applications and theoretical studies, combined with the equipment and process characteristics of the six-stand cold rolling unit, a set of comprehensive optimization setting methods for the three-tank emulsion concentration and temperature to control the oil film thickness between the roll and the strip and the slip as the constraint was established. Because the unit adopts multi-tank lubrication, the optimized setting is more detailed than the previous single-tank emulsion concentration and temperature setting in the distribution between the racks. As an indispensable substance in the cold rolling process, the rack emulsion plays an important role in the rolling stability of the cold rolling process by seeking suitable emulsion process parameters. In this context, the present invention fully combines the above-mentioned background content to optimize the emulsion concentration and temperature of the emulsion system. Summary of the invention

[0003] The present invention fully takes into account the slippage problem that occurs during the rolling process of ultra-high strength steel, and provides a method for optimizing the setting of the emulsion concentration and temperature of a six-stand cold rolling mill in combination with the characteristics of the three oil tanks participating in the lubrication of the emulsion system of the unit, that is, 1-3 frames share one oil tank, 4 frames have a separate oil tank, and 5 frames and 6 frames share one oil tank.

[0004] The present invention adopts the following technical solutions:

[0005] A method for optimizing the concentration and temperature of an emulsion of a six-stand cold rolling mill, wherein stands 1-3 share an oil tank, stand 4 has a separate oil tank, and stands 5 and 6 share an oil tank, the method comprising the following steps:

[0006] (1) Collect the equipment parameters of the six-stand cold rolling mill, including: working roll diameter D of stands 1-6 iw , Intermediate roller diameter D im, Support roller diameter D ib , working roll elastic modulus E, working roll Poisson's ratio ν, critical slip factor The relevant parameter subscript i represents the rack number, i = 1, 2, 3, 4, 5, 6;

[0007] (2) Collect the process rolling parameters of the six-stand cold rolling mill:

[0008] 1-6 stand rolling force P i , 1-6 rack strip steel inlet thickness h 0i With the outlet thickness h 1i , 1-6 rack rack strip inlet speed v 0i With the exit velocity v 1i , strip width B, 1-6 rack strip deformation resistance K si , Ra ri is the longitudinal roughness of the working roll surface of the i-th stand, and the inlet tension of the 1-6 stands σ 0i , 1-6 rack outlet tension σ 1i ;

[0009] (4) Collect characteristic parameters of process lubrication system, including:

[0010] Maximum and minimum concentrations of emulsion C max ,C min , the maximum and minimum temperatures of the emulsion T max ,T min , initial value of emulsion concentration C0, initial temperature t0, emulsion flow rate W of racks 1-6 i , liquid lubrication friction coefficient a, dry friction coefficient b, friction coefficient attenuation index β μj , density of emulsion ρ, emulsion flow loss coefficient k s , concentration influence coefficients c1, c2, c3, parameters a1, b1 of dynamic viscosity of lubricating oil under atmospheric pressure, and viscosity compression coefficient θ of emulsion;

[0011] (4) Set the intermediate calculation parameters: including the initial value of the objective function G rz0 , working roll roughness influence coefficient k rg , 1-6 rack oil film thickness upper limit ξ dh,i , 1-6 rack oil film thickness lower limit ξ rhs,i ;

[0012] (5) Set the emulsion concentration and temperature optimization variables X1 = {C1, t1} for racks 1-3, the emulsion concentration and temperature optimization variables X2 = {C2, t2} for racks 4, the emulsion concentration and temperature initial optimization variables X3 = {C3, t3} for racks 5-6, the emulsion concentration optimization step Δ1 = 0.001, and the emulsion temperature optimization step Δ2 = 0.1;

[0013] (6) Setting the intermediate process parameter k1 of the emulsion concentration of racks 1-3 = 0;

[0014] (7) Let the emulsion concentration of rack 1-3 be C1 = C min +k1Δ1;

[0015] (8) Setting the intermediate process parameter k2 of the 4-rack emulsion concentration to 0;

[0016] (9) Let the emulsion concentration of rack 4 be C2 = C min +k2Δ1;

[0017] (10) Setting the intermediate process parameter k3 of the 5-6 rack emulsion concentration to 0;

[0018] (11) Let the emulsion concentration of rack 5-6 be C3 = C min +k3Δ1;

[0019] (12) Setting the intermediate process parameter k4 of the emulsion temperature of racks 1-3 to 0;

[0020] (13) Let the emulsion temperature of rack 1-3 be t1 = t min +k4Δ2;

[0021] (14) Set the intermediate process parameter k5 of the 4-rack emulsion temperature to 0;

[0022] (15) Let the emulsion temperature of rack 4 be t2 = t min +k5Δ2;

[0023] (16) Set the intermediate process parameter k6 of the 5-6 rack emulsion temperature to 0;

[0024] (17) Let the emulsion temperature of rack 5-6 be t3 = t min +k6Δ2;

[0025] (18) Calculate the oil film thickness ξ on the upper and lower surfaces of the strip steel of rack 1-6 bs,i , bx,i , 1-6 Slip factor of upper and lower surfaces of rack Where: Oil film thickness ξ formula

[0026] Slip factor formula

[0027] (19) Determine whether it exceeds the limit: 1-6 upper and lower surfaces of the rack Is it true? If so, go to step (20), otherwise go to step (23);

[0028] (20) Calculate the rolling stability control objective function G of the upper surface of the strip wds (X wds ) and the lower surface rolling stability control objective function G wdx (X wdx ):

[0029] Upper surface:

[0030] G wds (X wds )=G wds1 (X wds1 )+G wds2 (X wds2 )+G wds3 (X wds3 )

[0031] Lower surface:

[0032] G wdx (X wdx )=G wdx1 (X wdx1 )+G wdx2 (X wdx2 )+G wdx3 (X wdx3 )

[0033] Where: G wds1 (X wds1 ), G wds2 (X wds2 ), G wds3 (X wds3 ) are the rolling stability control objective functions of the upper surface of the strip steel for combinations 1, 2, and 3 respectively; G wdx1 (X wdx1 ), G wdx2 (X wdx2 ), G wdx3 (X wdx3 ) are the rolling stability control objective functions of the lower surface of the strip steel for combinations 1, 2, and 3 respectively; α ξ1 , α ξ2 , α ξ3 The stability control coefficients of the combinations 1, 2, and 3 are 0.6, 0.94, and 0.63 respectively; (1-α ξ1 ), (1-α ξ3 ) is the maximum stability deviation control coefficient of combination 1 and 3;

[0034] (21) Calculation of the strip comprehensive rolling stability objective function G rz (X rz );

[0035] G rz (Xrz )=λ1G wds (X wds )+λ2G wdx (X wdx )

[0036] Where: λ1 is the rolling stability coefficient of the upper surface of the strip, which is 0.43; λ2 is the rolling stability coefficient of the lower surface of the strip, which is 0.57;

[0037] (22) Determine G rz (X rz )<G rz0 Is it true? If true, let G rz0 =G rz (X rz )Go to step (23); otherwise, go to step (23);

[0038] (23) Determine t rcmin ≤t3≤t rcmax Is it true? If it is true, let k6=k6+1 and go to step (17); otherwise, go to step (24);

[0039] (24) Determine t rcmin ≤t2≤t rcmax Is it true? If it is true, let k5=k5+1 and go to step (15); otherwise, go to step (25);

[0040] (25) Determine t rcmin ≤t1≤t rcmax Is it true? If it is true, let k4=k4+1 and go to step (13); otherwise, go to step (26);

[0041] (26) Judge C min ≤C3≤C max Is it true? If it is true, let k3 = k3 + 1 and go to step (11); otherwise, go to step (27);

[0042] (27) Judge C min ≤C2≤C max Is it true? If it is true, let k2 = k2 + 1 and go to step (9); otherwise, go to step (28);

[0043] (28) Judge C min ≤C1≤C max Is it true? If it is true, let k1=k1+1 and go to step (7); otherwise, go to step (29);

[0044] (29) Output the optimal value of the emulsion concentration and temperature of racks 1-3 X1 = {C1, t1}, the optimal value of the emulsion concentration and temperature of racks 4 X2 = {C2, t2}, and the optimal value of the emulsion concentration and temperature of racks 5-6 X3 = {C3, t3};

[0045] (30) Complete the optimal setting of emulsion concentration and temperature of the six-stand cold rolling mill.

[0046] The beneficial effects of the present invention are as follows: the present invention fully considers the influence of the emulsion concentration and the initial temperature on the stable rolling of the strip during the cold rolling process, takes the slip factor parameter as a constraint condition, and proposes an emulsion concentration and temperature optimization setting method for a six-stand cold rolling unit with the oil film thickness control on the upper and lower surfaces of the strip as the goal, thereby determining the optimal emulsion concentration and temperature, and improving the actual production efficiency and quality. Through the application of the present invention, the concentration and temperature optimization of the emulsion under the condition of multiple oil tanks is achieved, the slip phenomenon is reduced, the stability of the unit is guaranteed, the quality of the strip shape is improved, and certain economic benefits are brought. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is the overall flow chart of the present invention. DETAILED DESCRIPTION

[0048] Taking a six-stand cold rolling mill as an example, the method for optimizing the concentration and temperature of the emulsion suitable for the six-stand cold rolling mill according to the present invention is described in detail. The overall flow chart of the method is as follows: Figure 1 The steel type is IR8290E1 and the specification is 2.993*1098mm.

[0049] First, in step (1), the equipment parameters of the six-stand cold rolling mill are collected, mainly including: the working roll diameter D of the 1-6 stands iw ={455,455,455,360,455,455}mm, middle roller diameter D im ={530,530,530,625,530,530,}mm, support roller diameter D ib ={1370, 1370, 1370, 1370, 1370, 1370}mm, working roll elastic modulus E = 210Gpa, working roll Poisson's ratio ν = 0.3, critical slip factors are The relevant parameter subscript i represents the rack number, i = 1, 2, 3, 4, 5, 6;

[0050] Then, in step (2), the process rolling parameters of the six-stand cold rolling mill are collected: the rolling force P of the 1-6 stands i ={1281,1239,1233,1012,1104,988}t, 1-6 rack strip steel inlet thickness h 0i={2.993,2.518,2.092,1.740,1.429,1.219}mm and outlet thickness h 1i ={2.518,2.092,1.740,1.429,1.219,1.200}mm, 1-6 rack strip inlet speed v 0i ={155,179,222,263,325,379}m / min and outlet speed v 1i ={179,222,263,325,379,384}m / min, strip width B = 1098mm, 1-6 rack strip deformation resistance K si ={502,651,635,702,813,842}MPa, longitudinal roughness Ra of the working roll surface of the i-th stand ri ={0.596, 0.578, 0.556, 0.532, 0.512, 0.498}μm, 1-6 rack entrance tension σ 0i ={39.1, 153.2, 162.7, 173.7, 180.5, 189.3}MPa, 1-6 rack outlet tension σ 1i ={153.2, 16.27, 18.37, 190.5, 189.3, 47.4}MPa;

[0051] Then in step (3), the characteristic parameters of the process lubrication system are collected, mainly including: the maximum and minimum concentrations of the emulsion C max ,C min ={9%, 2%}, maximum and minimum emulsion temperatures T max ,T min ={62℃,50℃}, initial value of emulsion concentration C0=2%, initial temperature t0=50℃, emulsion flow rate W of racks 1-6 i ={989, 1221, 1138, 1288, 1293, 1035}, liquid lubrication friction coefficient a = 0.0127, dry friction coefficient b = 0.1149, friction coefficient attenuation index β μj =-4.983, density of emulsion ρ = 870 kg / m 3 , emulsion flow loss coefficient k s =0.75, concentration influence coefficients c1, c2, c3 = {2.91, -9.69, 1.792}, parameters of dynamic viscosity of lubricating oil under atmospheric pressure a1 = 3.82, b1 = 2.71, viscosity compression coefficient of emulsion θ = 0.01 MPa -1 ;

[0052] Then in step (4) the initial value of the objective function is set Working roll roughness influence coefficient krg =0.13, the upper limit of oil film thickness for racks 1-6 is ξ dh,i =0.55um, upper limit of oil film thickness for 1-6 racks ξ rhs,i =0.10um;

[0053] Then, in step (5), the initial optimization variables X1={C1, t1}={2%, 50°C} of the emulsion concentration and temperature of racks 1-3, X2={C2, t2}={2%, 50°C} of the emulsion concentration and temperature of racks 4, X3={C3, t3}={2%, 50°C} of the emulsion concentration and temperature of racks 5-6 are given, the optimization step length of emulsion concentration Δ1=0.001, and the optimization step length of emulsion temperature Δ2=0.1 are given;

[0054] Then in step (6), set the intermediate process parameter k1 of the emulsion concentration of racks 1-3 = 0

[0055] Then in step (7), the concentration of the emulsion in racks 1-3 is set to C1 = C min +k1Δ1=0.02,

[0056] Then in step (8), set the intermediate process parameter k2 of the 4-rack emulsion concentration to 0

[0057] Then in step (9), the concentration of the emulsion in the 4-rack is set to C2 = C min +k2Δ1=0.02;

[0058] Then, in step (10), the intermediate process parameter k3 of the emulsion concentration of the 5-6 rack is set to 0;

[0059] Then in step (11), the concentration of the emulsion in rack 5-6 is set to C3 = C min +k3Δ1=0.02;

[0060] Then, in step (12), the intermediate process parameter k4 of the emulsion temperature of racks 1-3 is set to 0;

[0061] Then in step (13), the emulsion temperature of rack 1-3 is set to t1 = t min +k4Δ2=50℃,

[0062] Then, in step (14), the intermediate process parameter k5 of the temperature of the emulsion of the 4-rack is set to 0;

[0063] Then in step (15), the temperature of the emulsion in rack 4 is set to t2 = t min +k5Δ2=50℃;

[0064] Then, in step (16), the intermediate process parameter k6 of the emulsion temperature of the 5-6 rack is set to 0;

[0065] Then, in step (17), the emulsion temperature of rack 5-6 is set to t3 = t min +k6Δ2=50℃;

[0066] Then, in step (18), the oil film thickness ξ on the strip surface of the 1-6 rack is calculated bxs,i ={0.363,0.318,0.285,0.253,0.231,0.201}um, oil film thickness on the lower surface of the strip ξ bxx,i ={0.311,0.268,0.237,0.221,0.191,0.183}um, 1-6 rack upper surface slip factor Lower surface slip factor

[0067] Then, in step (19), it is determined whether the limit is exceeded: 1-6 upper and lower surfaces of the rack Obviously, it is established, go to step (20);

[0068] Then, in step (20), the rolling stability control objective function G of the upper surface of the strip is calculated. wds (X wds )=0.13136, the lower surface rolling stability control objective function G wdx (X wdx )=0.18178, go to step (21);

[0069] Then, in step (21), the comprehensive rolling stability objective function G of the strip is calculated. rz (X rz )=0.16, go to step (22);

[0070] Then, in step (22), it is determined that G rz (X rz )<G rz0 Is it true? If true, let G rz0 =G rz (X rz )Go to step (23); otherwise, go to step (23);

[0071] Then, in step (23), t rcmin ≤t3≤t rcmax Is it true? If it is true, let k6=k6+1 and go to step (17); otherwise, go to step (24);

[0072] Then, in step (24), t rcmin ≤t2≤t rcmax Is it true? If it is true, let k5=k5+1 and go to step (15); otherwise, go to step (25);

[0073] Then, in step (25), t rcmin ≤t1≤t rcmax Is it true? If it is true, let k4=k4+1 and go to step (13); otherwise, go to step (26);

[0074] Then, in step (26), it is determined that C min ≤C3≤C max Is it true? If it is true, let k3 = k3 + 1 and go to step (11); otherwise, go to step (27);

[0075] Then, in step (27), it is determined that C min ≤C2≤C max Is it true? If it is true, let k2 = k2 + 1 and go to step (9); otherwise, go to step (28);

[0076] Then, in step (28), it is determined that C min ≤C1≤C max Is it true? If it is true, let k1=k1+1 and go to step (7); otherwise, go to step (29);

[0077] Then, in step (29), the optimal values ​​of the concentration and temperature of the emulsion in racks 1-3 are outputted as X1={C 1, t1}={3.7%,56℃},4-rack emulsion concentration, optimal temperature value X2={C 2, t2}={4.2%,53℃},5-6 rack emulsion concentration, optimal temperature value X3={C 3, t3}={3.9%,55℃};

[0078] The final step (30) completes the optimal setting of the emulsion concentration and temperature of the six-stand cold rolling mill.

[0079] The above contents are only used to illustrate the technical solution of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention made by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A method for optimizing the concentration and temperature of an emulsion in a six-stand cold rolling mill, wherein: 1-3 racks share one oil tank, 4 racks have one oil tank, 5 racks and 6 racks share one oil tank; the characteristics are: The method comprises the following steps: (1) Collect the equipment parameters of the six-stand cold rolling mill, including: working roll diameter D of stands 1-6 iw , Intermediate roller diameter D im , Support roller diameter D ib , working roll elastic modulus E, working roll Poisson's ratio ν, critical slip factor The relevant parameter subscript i represents the rack number, i = 1, 2, 3, 4, 5, 6; (2) Collect the process rolling parameters of the six-stand cold rolling mill: 1-6 stand rolling force P i , 1-6 rack strip steel inlet thickness h 0i With the outlet thickness h 1i , 1-6 rack rack strip inlet speed v 0i With the exit velocity v 1i , strip width B, 1-6 rack strip deformation resistance K si , Ra ri is the longitudinal roughness of the working roll surface of the i-th stand, and the inlet tension of the 1-6 stands σ 0i , 1-6 rack outlet tension σ 1i ; (3) Collect characteristic parameters of process lubrication system, including: Maximum and minimum concentrations of emulsion C max ,C min , the maximum and minimum temperatures of the emulsion T max ,T min , initial value of emulsion concentration C0, initial temperature t0, emulsion flow rate W of racks 1-6 i , liquid lubrication friction coefficient a, dry friction coefficient b, friction coefficient attenuation index β μj , density of emulsion ρ, emulsion flow loss coefficient k s , concentration influence coefficients c1, c2, c3, Parameters a1, b1 of dynamic viscosity of lubricating oil at atmospheric pressure, and viscosity compressibility coefficient θ of emulsion; (4) Set the intermediate calculation parameters: including the initial value of the objective function G rz0 , working roll roughness influence coefficient k rg , 1-6 rack oil film thickness upper limit ξ dh,i , 1-6 rack oil film thickness lower limit ξ rhs,i ; (5) Set the emulsion concentration and temperature optimization variables X1 = {C1, t1} for racks 1-3, the emulsion concentration and temperature optimization variables X2 = {C2, t2} for racks 4, the emulsion concentration and temperature initial optimization variables X3 = {C3, t3} for racks 5-6, the emulsion concentration optimization step Δ1 = 0.001, and the emulsion temperature optimization step Δ2 = 0.1; (6) Setting the intermediate process parameter k1 of the emulsion concentration of racks 1-3 = 0; (7) Let the emulsion concentration of rack 1-3 be C1 = C min +k1Δ1; (8) Setting the intermediate process parameter k2 of the 4-rack emulsion concentration to 0; (9) Let the emulsion concentration of rack 4 be C2 = C min +k2Δ1; (10) Setting the intermediate process parameter k3 of the 5-6 rack emulsion concentration to 0; (11) Let the emulsion concentration of rack 5-6 be C3 = C min +k3Δ1; (12) Setting the intermediate process parameter k4 of the emulsion temperature of racks 1-3 to 0; (13) Let the emulsion temperature of rack 1-3 be t1 = t min +k4Δ2; (14) Set the intermediate process parameter k5 of the 4-rack emulsion temperature to 0; (15) Let the emulsion temperature of rack 4 be t2 = t min +k5Δ2; (16) Set the intermediate process parameter k6 of the 5-6 rack emulsion temperature to 0; (17) Let the emulsion temperature of rack 5-6 be t3 = t min +k6Δ2; (18) Calculate the oil film thickness ξ on the upper and lower surfaces of the strip steel of rack 1-6 bs,i , bx,i , 1-6 Slip factor of upper and lower surfaces of rack Where: Oil film thickness ξ formula Slip factor formula (19) Determine whether it exceeds the limit: 1-6 upper and lower surfaces of the rack Is it true? If so, go to step (20), otherwise go to step (23); (20) Calculate the rolling stability control objective function G of the upper surface of the strip wds (X wds ) and the lower surface rolling stability control objective function G wdx (X wdx ): Upper surface: G wds (X wds )=G wds1 (X wds1 )+G wds2 (X wds2 )+G wds3 (X wds3 ) Lower surface: G wdx (X wdx )=G wdx1 (X wdx1 )+G wdx2 (X wdx2 )+G wdx3 (X wdx3 ) Where: G wds1 (X wds1 ), G wds2 (X wds2 ), G wds3 (X wds3 ) are the rolling stability control objective functions of the upper surface of the strip steel for combinations 1, 2, and 3 respectively; G wdx1 (X wdx1 ), G wdx2 (X wdx2 ), G wdx3 (X wdx3 ) are the rolling stability control objective functions of the lower surface of the strip steel for combinations 1, 2, and 3 respectively; α ξ1 , α ξ2 , α ξ3 The stability control coefficients of the combinations 1, 2, and 3 are 0.6, 0.94, and 0.63 respectively; (1-α ξ1 ), (1-α ξ3 ) is the maximum stability deviation control coefficient of combination 1 and 3; (21) Calculation of the strip comprehensive rolling stability objective function G rz (X rz ); G rz (X rz )=λ1G wds (X wds )+λ2G wdx (X wdx ) Where: λ1 is the rolling stability coefficient of the upper surface of the strip, which is 0.43; λ2 is the rolling stability coefficient of the lower surface of the strip, which is 0.57; (22) Determine G rz (X rz )<G rz0 Is it true? If true, let G rz0 =G rz (X rz )Go to step (23); otherwise, go to step (23); (23) Determine t rc min ≤t3≤t rc max Is it true? If it is true, let k6=k6+1 and go to step (17); otherwise, go to step (24); (24) Determine t rc min ≤t2≤t rc max Is it true? If it is true, let k5=k5+1 and go to step (15); otherwise, go to step (25); (25) Determine t rc min ≤t1≤t rc max Is it true? If it is true, let k4=k4+1 and go to step (13); otherwise, go to step (26); (26) Judge C min ≤C3≤C max Is it true? If it is true, let k3 = k3 + 1 and go to step (11); otherwise, go to step (27); (27) Judge C min ≤C2≤C max Is it true? If it is true, let k2 = k2 + 1 and go to step (9); otherwise, go to step (28); (28) Judge C min ≤C1≤C max Is it true? If it is true, let k1=k1+1 and go to step (7); otherwise, go to step (29); (29) Output 1-3 rack emulsion concentration, temperature optimal value X1 = {C 1, t1}, 4 rack emulsion concentration, temperature optimal value X2 = {C 2, t2}, 5-6 rack emulsion concentration, temperature optimal value X3 = {C 3, t3}; (30) Complete the optimal setting of emulsion concentration and temperature of the six-stand cold rolling mill.

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