A method for predicting width expansion in secondary cold rolling

Abstract

The present invention relates to a method for predicting the width expansion during secondary cold rolling, and belongs to the technical field of cold-rolled steel strip in the metallurgical industry. The technical solution comprises the following steps: Step 1: collecting process parameters of the steel strip during secondary cold rolling; Step 2: calculating the steel strip deformation resistance σ during the secondary cold rolling process; Step 3: establishing a secondary cold rolling force calculation model, and inversely calculating the friction coefficient μ based on the rolling force model; Step 4: solving the influence coefficient c of the steel strip width on the width expansion. b ; Step 4: Calculate the influence coefficient c of the tension on the width σ ; Step 5: Establish a calculation model for the width expansion of the strip during secondary cold rolling, and solve the strip width expansion Δb; The beneficial effect of the present invention is: by establishing a deformation resistance calculation model during the secondary cold rolling process, inversely calculating the friction coefficient and the influence coefficient of tension on the width expansion, the width expansion of the secondary cold rolling is finally calculated, and based on the strip width expansion, it is accurately judged whether the strip width deviation meets the accuracy requirements.

Description

Technical Field

[0001] The invention relates to a method for predicting width expansion of secondary cold rolling, and belongs to the technical field of cold-rolled strip steel in the metallurgical industry. Background Art

[0002] Secondary cold rolling is a process where cold-rolled strip is annealed and then cold-rolled again instead of being tempered. It is a method for producing thinner and higher-strength strip steel. Compared to tempering, secondary cold rolling has a higher reduction ratio, generally ranging from 30% to 50%.

[0003] Secondary cold rolling is generally a single-stand rolling mill or a double-stand rolling mill. The first rolling mill in the double-stand rolling mill is usually a cold rolling mill, and the second rolling mill is usually a skin pass mill. It is a process method that takes both cold rolling and skin pass into consideration.

[0004] During the secondary cold rolling process, due to the high reduction ratio, the strip width accuracy is one of the key control links. To ensure the width accuracy of the strip after the secondary cold rolling, it is necessary to accurately predict the secondary cold rolling width.

[0005] Secondary cold rolling is a crucial step in the production of thin strip. The presence of friction during the secondary cold rolling process causes resistance to metal flow, which in turn prevents the strip from flowing laterally, ultimately affecting the strip's width expansion. Obviously, the greater the rolling force, the greater the friction, and there is an inevitable influence between the two. Therefore, the key to calculating the width expansion during secondary cold rolling is firstly calculating the rolling force. In actual production, the effect of the rolling force on the strip is a widening trend, meaning that under the action of the vertical rolling force, the strip should extend in the width direction. The effect of the front and rear tensions on the strip is a widening trend, meaning that under the action of the front and rear tensile stresses, the strip should shrink in the width direction. Therefore, predicting the width expansion during secondary cold rolling is particularly important. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for predicting the width expansion of secondary cold rolling. By establishing a deformation resistance calculation model during the secondary cold rolling process, inversely calculating the friction coefficient and the influence coefficient of tension on the width expansion, the width expansion of the secondary cold rolling is finally calculated to solve the problems existing in the background technology.

[0007] The technical solution of the present invention is:

[0008] A method for predicting width expansion of secondary cold rolling comprises the following steps:

[0009] Step 1: Collect the process parameters of the strip in the secondary cold rolling state: secondary cold rolling rolling force P, strip width w, front tension σ1, back tension σ2, yield strength correction coefficient k1, work roll radius R, strip entrance thickness H, deformation zone length correction coefficient k2, widening amount influence coefficient k3, strip exit thickness h, strip yield strength σs , where: the yield strength correction coefficient k1 ranges from 1.1 to 2.0, the deformation zone length correction coefficient k2 ranges from 2.0 to 5.0, and the widening influence coefficient k3 ranges from 0.0001 to 0.0012;

[0010] Step 2: Calculate the strip deformation resistance σ during the secondary cold rolling process;

[0011]

[0012] Step 3: Establish a secondary cold rolling force calculation model and inversely calculate the friction coefficient μ based on the rolling force model;

[0013] P=k2wσL

[0014] Where L is the length of the deformation zone,

[0015] ε is the strip reduction rate;

[0016]

[0017] Δh=Hh;

[0018] Step 3: Calculate the influence coefficient c of strip width on width expansion b ;

[0019]

[0020] Where,

[0021]

[0022] Step 4: Calculate the influence coefficient c of the tension on the width σ ;

[0023]

[0024] Step 5: Establish a calculation model for the width expansion of the secondary cold rolled strip and solve the strip width expansion Δb;

[0025]

[0026] According to the strip width expansion Δb, it is judged whether the strip width deviation meets the accuracy requirements.

[0027] The deformation zone length refers to the horizontal projection length of the contact arc between the workpiece and the roller during the rolling process.

[0028] The secondary cold rolling is performed using two rolling mills, the first rolling mill is a cold rolling mill, and the second rolling mill is a skin pass mill. The collected process parameters under the secondary cold rolling state are the process parameters of the first rolling mill, and the solved strip width expansion Δb is the width expansion of the first rolling mill.

[0029] The secondary cold rolling is performed by using a single-stand rolling mill.

[0030] The beneficial effects of the present invention are: by establishing a deformation resistance calculation model during the secondary cold rolling process, inversely calculating the friction coefficient and the influence coefficient of tension on the width expansion, the width expansion of the secondary cold rolling is finally calculated, and based on the width expansion of the strip, it is accurately judged whether the width deviation of the strip meets the accuracy requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Flowchart of the present invention; DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and through examples.

[0033] Refer to the attached Figure 1 A method for predicting width expansion of secondary cold rolling comprises the following steps:

[0034] Step 1: Collect the process parameters of the strip in the secondary cold rolling state: secondary cold rolling rolling force P, strip width w, front tension σ1, back tension σ2, yield strength correction coefficient k1, work roll radius R, strip entrance thickness H, deformation zone length correction coefficient k2, widening amount influence coefficient k3, strip exit thickness h, strip yield strength σ s , where: the yield strength correction coefficient k1 ranges from 1.1 to 2.0, the deformation zone length correction coefficient k2 ranges from 2.0 to 5.0, and the widening influence coefficient k3 ranges from 0.0001 to 0.0012;

[0035] Step 2: Calculate the strip deformation resistance σ during the secondary cold rolling process;

[0036]

[0037] Step 3: Establish a secondary cold rolling force calculation model and inversely calculate the friction coefficient μ based on the rolling force model;

[0038] P=k2wσL

[0039] Where L is the length of the deformation zone,

[0040] ε is the strip reduction rate;

[0041]

[0042] Δh=Hh;

[0043] Step 3: Calculate the influence coefficient c of strip width on width expansion b ;

[0044]

[0045] Where,

[0046]

[0047] Step 4: Calculate the influence coefficient c of the tension on the width σ ;

[0048]

[0049] Step 5: Establish a calculation model for the width expansion of the secondary cold rolled strip and solve the strip width expansion Δb;

[0050]

[0051] According to the strip width expansion Δb, it is judged whether the strip width deviation meets the accuracy requirements.

[0052] Example 1: Secondary cold rolling of strip steel using a single-stand rolling mill

[0053] (1) The equipment and process parameters of the secondary cold rolling state were collected: secondary cold rolling force P was 4000 kN, strip width w was 800 mm, front tension σ1 was 152 MPa, rear tension σ2 was 104 MPa, yield strength correction coefficient k1 was 1.5, working roll radius R was 185 mm, strip entrance thickness H was 0.2 mm, deformation zone length correction coefficient k2 was 2.5, widening coefficient k3 was 0.0008, strip exit thickness h was 0.16 mm, strip yield strength σ s 550MPa;

[0054] (2) Calculate the strip deformation resistance σ during the secondary cold rolling process;

[0055]

[0056] The solution shows that the strip deformation resistance is σ = 697 MPa;

[0057] (3) Establish a calculation model for the rolling force of secondary cold rolling and inversely calculate the friction coefficient μ based on the rolling force model;

[0058]

[0059] Where L is the length of the deformation zone,

[0060] ε is the strip reduction rate;

[0061]

[0062] Δh=Hh;

[0063] The solution yields the value of the friction coefficient as μ = 0.10;

[0064] (4) Solve the coefficient c of the influence of strip width on width expansion b ;

[0065]

[0066] Where,

[0067]

[0068] The coefficient of influence of strip width on width expansion is obtained as c b =0.42;

[0069] (5) Solve the coefficient c of the influence of tension on the expansion σ ;

[0070]

[0071] The coefficient of influence of tension on the expansion is obtained as c σ =0.67;

[0072] (6) Establish a calculation model for the width expansion of the secondary cold rolled strip and solve the width expansion Δb of the strip;

[0073]

[0074] The solution is that the strip width expansion is Δb = 0.09 mm;

[0075] The product width accuracy requirement is that the strip width deviation does not exceed 0.15mm.

[0076] 0.09mm<0.15mm, meeting product precision requirements.

[0077] Example 2: The secondary rolling of strip steel adopts a double stand, the first stand is the secondary rolling mill, and the second stand is the skin pass mill.

[0078] (1) The equipment and process parameters of the first rolling mill were collected: secondary cold rolling force P was 5000 kN, strip width w was 1000 mm, front tension σ1 was 148 MPa, rear tension σ2 was 102 MPa, yield strength correction coefficient k1 was 1.5, working roll radius R was 185 mm, strip entrance thickness H was 0.22 mm, deformation zone length correction coefficient k2 was 2.5, widening coefficient k3 was 0.0008, strip exit thickness h was 0.17 mm, strip yield strength σ s 550MPa;

[0079] (2) Calculate the strip deformation resistance σ during the secondary cold rolling process;

[0080]

[0081] The solution shows that the strip deformation resistance is 700MPa;

[0082] (3) Establish a calculation model for the rolling force of secondary cold rolling and inversely calculate the friction coefficient μ based on the rolling force model;

[0083]

[0084] =5000kN

[0085] Where, ε is the strip reduction rate;

[0086]

[0087] Δh=Hh;

[0088] The solution yields a value of 0.12 for the coefficient of friction;

[0089] (4) Solve the coefficient c of the influence of strip width on width expansion b ;

[0090]

[0091] Where,

[0092]

[0093] The solution shows that the influence coefficient of strip width on width expansion is 0.46;

[0094] (5) Solve the coefficient c of the influence of tension on the expansion σ ;

[0095]

[0096] The solution shows that the coefficient of influence of tension on the width expansion is 0.67;

[0097] (6) Establish a calculation model for the width expansion of the secondary cold rolled strip and solve the width expansion Δb of the strip;

[0098]

[0099] The solution shows that the strip width expansion is 0.13mm; the product width accuracy requirement is that the strip width deviation does not exceed 0.15mm. After judgment, 0.13mm<0.15mm, which meets the product accuracy requirements.

Claims

1. A method for predicting width expansion of secondary cold rolling, characterized by: The following steps are involved: Step 1: Collect the process parameters of the strip in the secondary cold rolling state: secondary cold rolling rolling force P, strip width w, front tension σ1, back tension σ2, yield strength correction coefficient k1, work roll radius R, strip entrance thickness H, deformation zone length correction coefficient k2, widening amount influence coefficient k3, strip exit thickness h, strip yield strength σ s , where: the yield strength correction coefficient k1 ranges from 1.1 to 2.0, the deformation zone length correction coefficient k2 ranges from 2.0 to 5.0, and the widening influence coefficient k3 ranges from 0.0001 to 0.0012; Step 2: Calculate the strip deformation resistance σ during the secondary cold rolling process; Step 3: Establish a secondary cold rolling force calculation model and inversely calculate the friction coefficient μ based on the rolling force model; P=k2wσL Where L is the length of the deformation zone, ε is the strip reduction rate; Δh=Hh; Step 3: Calculate the influence coefficient c of strip width on width expansion b ; Where, Step 4: Calculate the influence coefficient c of the tension on the width σ ; Step 5: Establish a calculation model for the width expansion of the secondary cold rolled strip and solve the strip width expansion Δb; 。 2. The method for predicting width expansion of secondary cold rolling according to claim 1, characterized in that: According to the strip width expansion Δb, it is judged whether the strip width deviation meets the accuracy requirements.

3. The method for predicting the width expansion of secondary cold rolling according to claim 2, characterized in that: The deformation zone length refers to the horizontal projection length of the contact arc between the workpiece and the roller during the rolling process.

4. The method for predicting width expansion of secondary cold rolling according to claim 3, characterized in that: The secondary cold rolling is carried out using two rolling mills, the first rolling mill is a cold rolling mill, and the second rolling mill is a skin pass mill. The collected process parameters under the secondary cold rolling state are the process parameters of the first rolling mill, and the solved strip width expansion Δb is the width expansion of the first rolling mill.

5. The method for predicting width expansion of secondary cold rolling according to claim 3, characterized in that: The secondary cold rolling is carried out using a single-stand rolling mill.

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