A method for setting limiting rolling process parameters suitable for a precision stainless steel strip cold continuous rolling process

Abstract

The present application relates to the field of precision stainless steel strip rolling technology, in particular to a limit rolling thin process parameter setting method suitable for the cold continuous rolling process of precision stainless steel strip. The present application fully combines the cold continuous rolling process characteristics and the combined number of reduction schedule, proposes the concept of the reduction proportion benchmark of each stand of the cold continuous rolling mill, establishes the "reverse parameter searching-forward constraint" calculation method of the maximum total reduction amount of the cold continuous rolling process of precision stainless steel strip, completes the optimized distribution of the reduction amount above the reduction proportion benchmark of each stand, realizes the rapid optimization setting of the limit rolling thin process parameters, so as to achieve the purpose of the stable rolling of precision stainless steel strip.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of precision stainless steel strip rolling technology, and particularly relates to a method for setting limit rolling process parameters suitable for a precision stainless steel strip cold continuous rolling process. BACKGROUND

[0002] In recent years, with the upgrading of manufacturing industry and the development of new material technology, the market demand for precision stainless steel strips has been growing continuously, and the precision stainless steel strips are widely used in the fields of aerospace, medical devices, precision machinery and the like. Meanwhile, the downstream application fields have put forward higher and higher requirements on the thickness of the stainless steel strip products, and the rolling technology is also adapting to produce thinner precision stainless steel strip products to meet the needs of different industries. Due to the influence of rolling mill equipment capacity, material work hardening and rolling process parameters, the limit thinning of the product thickness in the precision stainless steel strip cold continuous rolling process is difficult to break through, which seriously restricts the expansion of the stainless steel product outline on site. Therefore, under the premise of not changing the rolling equipment and material properties, the optimization setting of the rolling process parameters has become a common problem to break through the limit rolling thickness of the stainless steel strip.

[0003] The limit rolling capacity of the stainless steel strip cold continuous rolling mill train not only needs to evaluate the maximum total reduction for a specific stainless steel strip product, but also needs to take into account the production efficiency of the mill train. The setting of the reduction schedule of the cold continuous rolling mill train determines the deformation resistance of the strip in each pass, which in turn determines the friction coefficient of the deformation zone in each pass under specific lubrication conditions and rolling speed, and the influence of the front and rear tension of each rack on the plastic deformation of the strip in each pass determines the rolling force in each pass. The rolling force in each pass needs to be ensured to be within the maximum allowable value of the rolling force of each rack. At the same time, the rolling speed and rolling torque of the strip at the outlet of each rack determine the rolling power under each pass, and the rolling power under each pass needs to be ensured to be within the maximum allowable value of the rolling power of each rack. In this way, under the premise that the rolling force and the rolling power of each rack do not exceed the maximum allowable value of the rack, how the reduction schedule is distributed and how the rolling speed is set directly determines the maximum total reduction of the stainless steel strip after cold continuous rolling. However, due to the large number of racks of the cold continuous rolling mill train, the optimization calculation of the reduction schedule is a complex process. The change of the reduction amount of one rack will not only cause the change of the rolling force and the rolling power of the current rack, but also cause the change of the rolling force and the rolling power of the following racks. Therefore, each rack cannot be optimized independently, which leads to the difficulty in determining the limit process parameters for stable thin rolling of the precision stainless steel strip. SUMMARY

[0004] Therefore, the present application aims to provide a method for setting the limit rolling process parameters suitable for the cold continuous rolling process of precision stainless steel strips.

[0005] To achieve the above-mentioned purpose, the technical solution of the present application is as follows:

[0006] A method for setting the limit rolling process parameters suitable for the cold continuous rolling process of precision stainless steel strips, comprising the following steps:

[0007] S1, collecting the equipment and process parameters of the cold continuous rolling mill, including: the number of stands n, the work roll diameter D of the i-th stand wi , the maximum rolling force allowable value P of the i-th stand imax , the maximum rolling power allowable value F of the i-th stand imax , and the friction coefficient μ of the i-th stand i , wherein i=1, 2, 3…n;

[0008] S2, collecting the material parameters of the precision stainless steel strip to be rolled, including: the incoming thickness h0, the incoming width B, the initial deformation resistance σ s0 , and the carbon equivalent C of the stainless steel strip ac ;

[0009] S3, defining the strip reduction, strip reduction rate and rolling speed of each stand, and giving the rolling speed of the n-th stand;

[0010] S4, giving the deformation resistance calculation model, rolling force calculation model and rolling power calculation model of each stand;

[0011] S5, setting the optimization step size Δ, step size coefficient k z , and maximum total reduction Δh zmax ;

[0012] S6, setting the reduction proportion reference of each stand in the cold continuous rolling process of the precision stainless steel strip;

[0013] S7, judging whether the reduction corresponding to the reduction proportion reference of each stand can meet the constraint condition: P i ≤P imax and F i≤F imax (1≤i≤n), where P i F is the rolling force of the i-th stand. i The rolling power of the i-th stand; if satisfied, it indicates that the unit has the capacity to handle a reduction ratio above the benchmark. The amount of reduction, where a i The pressing ratio of the i-th rack is the benchmark; if it is not satisfied, it indicates that Δh zmax If the setting exceeds the unit's capacity, then let k z =k z +1, repeat the above process until the reduction amount corresponding to the reduction ratio benchmark of each rack meets the constraint conditions;

[0014] S8. Define the frame step length coefficients from 1 to n as k1, k2, k3, ..., k n The cumulative number of optimization step-size increases is Where k i The step size factor for the i-th rack is above the base ratio. The total number of optimization steps required for the compression amount is: The expression for the reduction of each frame is Δh i =a i Δh zmax +k i Δ; where Δh i Let be the strip reduction amount of the i-th frame;

[0015] S9. Calculate the distribution of the reduction amount for frames 1 to n.

[0016] S10, Determine k l ≥n s Check if the condition is true; if true, proceed to step S11; if false, let k... z =k z +1, proceed to step S5;

[0017] S11, Output k z and maximum total reduction Δh zmax ;

[0018] S12, Output the reduction amount and reduction distribution ratio of each stand in the cold continuous rolling process of precision stainless steel strip.

[0019] Furthermore, the expression for the strip reduction amount of each frame in S3 is as follows:

[0020] Δh i =h i-1 -h i

[0021] In the formula, Δh i h represents the strip reduction of the i-th frame. ih i-1 is the strip exit thickness of the i-1stand;

[0022] The expression of the strip reduction rate of each stand is:

[0023]

[0024] wherein ε i is the strip reduction rate of the i stand;

[0025] The expression of the rolling speed of each stand is:

[0026]

[0027] wherein V i is the rolling speed of the i stand, V n is the rolling speed of the n stand, h n is the strip exit thickness of the n stand.

[0028] Further, the deformation resistance calculation model in S4 is:

[0029]

[0030] wherein σ si is the deformation resistance of the i stand; σ s(i-1) is the deformation resistance of the i-1stand; k vi is the speed influence coefficient, k vi = (V i ε i / l i v0) n , wherein li is the projection length of the contact arc in the rolling process of the i stand, which is obtained from the rolling force calculation model, v0 is the reference deformation speed, v0 = 1 s －1 ; w is a material parameter, w = 0.005; m is the work hardening performance index, m = 110 (1 + 2C ac ) / σ s0 ;

[0031] The rolling force calculation model is:

[0032] P i = f P (h i-1 ,h i ,B,T i-1,i ,T i,i+1 ,σ si ,D wi ,μ i )

[0033] wherein P iis the rolling force of the ith stand; T i-1,i is the back tension, T i,i+1 is the front tension; wherein the back tension T i-1,i is greater than the front tension T i,i+1 is the reference value of the mill train;

[0034] The rolling power calculation model is:

[0035] F i = f F (h i-1 , h i , B, P i , V i );

[0036] In the formula, F i is the rolling power of the ith stand.

[0037] Further, in the S5, the optimization step size Δ = 0.001 is set, the step size coefficient k z = 1, and the maximum total reduction Δh zmax = h0-k z Δ.

[0038] Further, in the S6, according to the reduction distribution rule of each stand in the precision stainless steel strip cold continuous rolling process, the minimum reduction proportion of each stand is set as a1, a2, a3,..., a n , and half of the total reduction is fixedly distributed in advance.

[0039] Further, the specific steps of the S9 are as follows:

[0040] S9-1, let j = 1;

[0041] S9-2, let k j = 0;

[0042] S9-3, calculate the reduction of the jth stand, Δh j = a j Δh zmax +k j Δ;

[0043] S9-4, according to the step S4, calculate the rolling force P i and the rolling power F i of the jth to nth stand, wherein j≤i≤n;

[0044] S9-5, judge whether P i > P imax or F i > F imax (j≤i≤n) is true; if true, go to step S9-6; if not true, let kj =k j +1 Proceed to step S9-3;

[0045] S9-6, Determine P j With F j Is it beyond the limit? If P j >P jmax or F j >F jmax Let k j =k j -1, proceed to step S9-7; if P j ≤P jmax And F j ≤F jmax Let k z =k z +1, then proceed to step S5;

[0046] S9-7. Determine if j < n is true; if true, let j = j + 1 and go to step S9-2; if false, go to step S9-8.

[0047] S9-8. Calculate the cumulative number of times the optimization step size is increased, k. l k l = k1 + k2 + k3 + ... + k n .

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] This invention combines the processing deformation characteristics of stainless steel strip cold rolling with the ultimate capacity of the rolling mill equipment. Based on a deformation resistance model, it achieves linked calculation of the rolling force and rolling power of each stand in the cold rolling mill, and constrains them with the maximum rolling force and maximum rolling power of each stand. This avoids the drawback of determining the reduction amount of each stand in isolation, which leads to the difficulty in achieving the ultimate thinning. At the same time, considering that the total reduction rate of stainless steel strip cold rolling is generally around 60-80% or even higher, in order to reduce the amount of parameter search calculation for the combination of reduction procedures, a calculation method of "reverse parameter search - forward constraint" for the maximum total reduction of stainless steel strip is proposed. This enables rapid optimization setting of the ultimate thinning process parameters, improves the specification expansion capability of the cold rolling mill and the stability of ultra-thin rolling of precision stainless steel strip. Attached Figure Description

[0050] Figure 1 A flowchart for calculating the maximum total reduction in the cold continuous rolling process of precision stainless steel strip;

[0051] Figure 2 A flowchart for calculating the reduction distribution of each stand in a six-stand cold rolling mill. Detailed Implementation

[0052] For the purpose of facilitating the understanding of the present application, a more comprehensive description will be given below. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided for the purpose of making the disclosure of the present application more thorough and comprehensive.

[0053] Embodiment

[0054] A limit rolling thin process parameter setting method suitable for a precision stainless steel strip cold continuous rolling process, the maximum total reduction calculation overall process of the precision stainless steel strip cold continuous rolling process is as shown in Figure 1 The specific execution steps are as follows:

[0055] S1, collect the equipment and process parameters of the cold continuous rolling mill set, taking a six-stand cold continuous rolling mill set as an example, including: the work roll diameter D wi of the i-th stand, the maximum rolling force allowable value P imax of the i-th stand, the maximum rolling power allowable value F imax of the i-th stand, and the friction coefficient μ i of the i-th stand, where i = 1, 2, 3, …, 6; as shown in Table 1;

[0056] Table 1: Equipment and process parameters of the cold continuous rolling mill set

[0057]

[0058] S2, collect the parameters of the precision stainless steel strip material to be rolled, the incoming thickness h0=2.533mm, the incoming width B=900mm, the initial deformation resistance σ s0 =590MPa, the carbon equivalent C ac of the stainless steel strip material =0.067%;

[0059] S3, define the related process parameters, including: the strip reduction of each stand, the strip reduction rate, and the rolling speed; wherein,

[0060] The expression of the strip reduction of each stand is:

[0061] Δh i =h i-1 -h i

[0062] In the formula, Δh i is the strip reduction of the i-th stand, h i is the strip outlet thickness of the i-th stand, and h i-1 is the strip outlet thickness of the i-1-th stand;

[0063] The expression of the strip reduction rate of each stand is:

[0064]

[0065] wherein ε i is the strip reduction rate of the i-th stand;

[0066] The expression of the rolling speed of each stand is:

[0067]

[0068] wherein V i is the rolling speed of the i-th stand, V6 is the rolling speed of the 6-th stand, and h6 is the strip outlet thickness of the 6-th stand.

[0069] S4, a relevant calculation model is given, including a deformation resistance calculation model of each stand, a rolling force calculation model and a rolling power calculation model; wherein,

[0070] The deformation resistance calculation model is:

[0071]

[0072] wherein σ si is the deformation resistance of the i-th stand; σ s(i-1) is the deformation resistance of the i-th-1 stand; k vi is a speed influence coefficient, k vi = (V i ε i / l i v0) n , wherein li is the projection length of the contact arc in the rolling process of the i-th stand, which is obtained from the rolling force calculation model, and v0 is the reference deformation speed, v0 = 1 s －1 ; w is a material parameter, w = 0.005; m is the work hardening performance index, m = 110 (1 + 2C ac ) / σ s0 ;

[0073] The rolling force calculation model adopts Hill formula, which can be described as:

[0074] P i = f P (h i-1 ,h i ,B,T i-1,i ,T i,i+1 ,σ si ,D wi ,μ i )

[0075] wherein P i is the rolling force of the i-th stand, T i-1,i is the back tension; T i,i+1 is the front tension; wherein the back tension T i-1,i and the front tension Ti,i+1 The reference value of the unit is 300 kN;

[0076] The rolling power calculation model adopts the model of the rolling mill machine, which can be described as:

[0077] F i = f F (h i-1 , h i , B, P i , V i );

[0078] In the formula, F i is the rolling power of the i-th stand.

[0079] S5, set the optimization step size Δ = 0.001, the step size coefficient is k z (initial value is 1), and the maximum total reduction is Δh zmax = h0-k z Δ;

[0080] S6, set the reference of the reduction ratio of each stand in the precision stainless steel strip cold continuous rolling process;

[0081] According to the reduction distribution rule of each stand in the precision stainless steel strip cold continuous rolling process, the reduction ratio reference of each stand process is set, as shown in Table 2, and where a i is the reduction ratio reference of the i-th stand.

[0082] Table 2 Reference of reduction ratio of each stand in precision stainless steel strip cold continuous rolling process

[0083] Rack F1 F2 F3 F4 F5 F6 Reduction ratio reference 20％ 12％ 10％ 8％ 1％ 0.1％

[0084] S7, according to the reduction ratio reference of the cold continuous rolling, it is judged whether the reduction amount corresponding to the reduction ratio reference of each stand can meet the constraint condition: P i ≤ P imax and F i ≤ F imax (1≤i≤6), it is calculated that when the maximum total reduction is Δh zmax = h0-k z Δ = 2.533-1×0.001 = 2.532 (mm), the constraint condition cannot be met, which indicates that Δh zmax is set to exceed the unit capacity, so k z = k z +1, the above process is repeated until the reduction amount corresponding to the reduction ratio reference of each stand meets the constraint condition, at this time k z = 277, Δh zmax = h0-k zΔ = 2.533 - 277 x 0.001 = 2.256 (mm);

[0085] S8, define 1-6 rack step length coefficient respectively k1, k2, k3, k4, k5, k6, cumulative increase optimization step number is k l =k1+k2+k3+k4+k5+k6, the compression ratio above the base The total number of down amount of each rack needs to be optimized The expression of the down amount of each rack is as follows:

[0086]

[0087] S9, the down amount of 1-6 racks is calculated;

[0088] S9-1, let j = 1;

[0089] S9-2, let k1 = 0;

[0090] S9-3, calculate the down amount of the first rack, Δh1=a1Δh zmax +k1Δ=20% x 2.256+0=0.4512mm;

[0091] S9-4, according to step S4, calculate the rolling force P of 1-6 racks i And rolling power F i , where 1≤i≤6;

[0092] S9-5, judge P i >P imax Or F i >F imax (1≤i≤6) is true? If true, go to step S9-6; if not, let k1=k1+1 go to step S9-3; after calculation, the inequality is not true, let k1=k1+1 go to step S9-3, finally when k1=158, the inequality is true, go to step S9-6;

[0093] S9-6, judge P1 and F1 whether out of limit? If P1>P 1max Or F1>F 1max , let k1=k1-1, go to step S9-7; if P1≤P 1max And F1≤F 1max , let k z =k z +1, then go to step S5; after calculation, the first rack P1>P 1max , F1>F 1max , let k1=k1-1, go to step S9-7;

[0094] S9-7, judge whether j < n is established? If established, let j = j + 1, turn into step S9-2; if not established, turn into step S9-8; at this time j = 1 < n = 6, let j = j + 1, turn into step S9-2, until j < n is not established;

[0095] S9-8, calculate the accumulated increase optimization step length number k l , k l = k1 + k2 + k3 + k4 + k5 + k6 = 738

[0096] S10, judge whether k l ≥ n s is established? If established, turn into step S11; if not established, let k z = k z + 1, turn into step S5; through calculation, at this time not established, let k z = k z + 1, turn into step S5, until the inequality is established;

[0097] S11, output k z = 492 and the maximum total reduction Δh zmax = h0 - k z Δ = 2.041 (mm) ;

[0098] S12, output the reduction of each rack in the precision stainless steel strip cold continuous rolling process and the reduction distribution ratio, as shown in Table 3.

[0099] Table 3 Precision stainless steel strip limit rolling thin process parameters and reduction distribution ratio

[0100] Rack F1 F2 F3 F4 F5 F6 Reduction ratio 0.621 mm 0.588 mm 0.321 mm 0.276 mm 0.219 mm 0.016 mm Distribution ratio 30.43％ 28.81％ 15.73％ 13.52％ 10.73％ 0.78％

[0101] The above only describes the embodiments of the present application for better explaining the present application, and is not a limitation, any modification or equivalent replacement without departing from the spirit and scope of the present application, all belong to the scope covered by the present application.

Claims

1. A method for setting process parameters for extreme thinning of a stainless steel strip suitable for a precision cold continuous rolling process, characterized in that, The method comprises the following steps: S1, collect the equipment and process parameters of the cold continuous rolling mill train, including: the number of stands n, the work roll diameter D of the i-th stand wi , the maximum rolling force allowable value P of the i-th stand imax , the maximum rolling power allowable value F of the i-th stand imax and the friction coefficient μ of the i-th stand i , wherein i = 1, 2, 3, …, n; S2, collect the parameters of the precision stainless steel strip material to be rolled, including: incoming thickness h0, incoming width B, initial deformation resistance σ s0 carbon equivalent C ac ; S3, defining the strip reduction of each stand, the strip reduction rate and the rolling speed, and giving the rolling speed of the nth stand; S4, giving the deformation resistance calculation model, the rolling force calculation model and the rolling power calculation model of each stand; S5, set the optimization step size Δ, step size coefficient k z with the maximum total pressure under the amount of Δh zmax ; S6, setting the reduction ratio reference of each stand in the precision stainless steel strip cold continuous rolling process; S7, judge whether the corresponding amount of reduction of the reduction ratio reference of each stand can meet the constraint condition: P i ≤ P imax and F i ≤ F imax (1≤i≤n), wherein P i is the rolling force of the i-th stand, F i is the rolling power of the i-th stand; if it is satisfied, it means that the unit has a margin to bear the reduction amount above the reduction ratio reference , wherein a i is the reduction ratio reference of the i-th stand; if it is not satisfied, it means that Δh zmax is set to exceed the unit capacity, then k z =k z +1, repeat the above process until the corresponding amount of reduction of the reduction ratio reference of each stand meets the constraint condition; S8、define 1~n rack step length coefficient respectively k1, k2, k3,..., kn n , cumulative increase in the number of optimization step length is Where k i is the step length coefficient of the i-th rack, the reference above the reduction ratio The total reduction amount needs to optimize the number of steps The expression of the reduction amount of each rack is Δh i =a i Δh zmax +k i Δ; wherein Δh i is the strip reduction amount of the i-th rack; S9, performing distribution calculation on the reduction of the 1st to nth stands; S10, Determine k l ≥n s Check if the condition is true; if true, proceed to step S11; if false, let k... z =k z +1, proceed to step S5; S11, output k z and maximum total pressure underflow Δh zmax ; S12, outputting the reduction of each stand in the precision stainless steel strip cold continuous rolling process and the reduction distribution ratio.

2. A method of setting process parameters for extreme thinning of a stainless steel strip in a cold continuous rolling process as claimed in claim 1, wherein, The expression of the strip reduction of each stand in S3 is: Δh i = h i-1 - h i where Δh i is the strip reduction of the i-th stand, h i is the strip exit thickness of the i-th stand, h i-1 is the strip exit thickness of the i-1-th stand; The expression of the strip reduction rate of each stand is: where ε i is the strip reduction for the i-th stand; The expression of the rolling speed of each stand is: wherein V i is the rolling speed of the i-th stand, V n is the rolling speed of the n-th stand, h n is the strip exit thickness of the n-th stand.

3. A method of setting process parameters for extreme thinning of a stainless steel strip in a cold continuous rolling process as claimed in claim 2, wherein, The deformation resistance calculation model in S4 is: wherein σ si is the deformation resistance of the i-th stand; σ s(i-1) is the deformation resistance of the i-1-th stand; k vi is the speed influence coefficient, k vi = (V i ε i / l i v0) n wherein li is the projected length of the contact arc of the i-th stand during rolling, obtained from the rolling force calculation model, v0 is the reference deformation speed, v0 = 1 s －1 ; w is a material parameter, w = 0.005; m is the work hardening property index, m = 110 (1 + 2C ac ) / σ s0 ; The rolling force calculation model is: P i = f P (h i-1 , h i , B, T i-1,i , T i,i+1 , σ si , D wi , μ i ) In the formula, P i is the rolling force of the i-th stand, T i-1,i is the back tension, T i,i+1 is the front tension; wherein the back tension T i-1,i and the front tension T i,i+1 are the reference values of the mill train; The rolling power calculation model is: F i = f F (h i-1 , h i , B, P i , V i ); In the formula, F i is the rolling power of the i-th stand.

4. A method of setting process parameters for extreme thinning of a stainless steel strip in a cold continuous rolling process as claimed in claim 3, wherein, The S5 is set to optimize step size Δ = 0.001, step size coefficient k z = 1, the maximum total pressure drop Δh zmax = h0-k z Δ.

5. A method of setting process parameters for extreme thinning of a stainless steel strip in a cold continuous rolling process as claimed in claim 4, wherein, The S6 sets the minimum reduction ratio of each rack as a1, a2, a3,..., aN according to the reduction distribution rule of each rack in the cold continuous rolling process of the precision stainless steel strip. n , and Half of the total reduction is allocated in advance.

6. A method of setting process parameters for extreme thinning of a stainless steel strip in a cold continuous rolling process as claimed in claim 5, wherein, The specific steps of S9 are as follows: S9-1, let j=1; S9-2, let k j = 0; S9-3, calculate the press-down amount of the jth rack, Ah j = a j Ah zmax + k j Ah S9-4, calculating the rolling force P of the j~n stands according to step S4 i with the rolling power F i wherein j≤i≤n; S9-5, judge P i >P imax or F i >F imax (j < i < n) is true; if true, go to step S9-6; If not, let k j = k j + 1 go to step S9-3; S9-6, judge P j With F j Whether the limit; if P j >P jmax Or F j >F jmax , let k j =k j -1, turn into step S9-7; if P j ≤P jmax And F j ≤F jmax , let k z =k z +1, then turn into step S5; S9-7, judge whether j<n is true; if true, let j=j+1, and turn to step S9-2; if not true, turn to step S9-8; S9-8, calculate the cumulative increase in the number of optimization steps k l , k l = k1+ k2+ k3+... + k n .

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