A method for eliminating the defect of width reduction in a 6-high 5-stand tandem cold rolling mill

Abstract

The present invention relates to the technical field of cold-rolled strip steel, and particularly relates to a method for eliminating the narrowing defect of a 6-high 5-stand tandem cold rolling mill. 1) Calculate the unit tension between the first cold rolling mill and the second cold rolling mill according to the following formula: T1 = Y×K1+(δ - 39%)×K2 - (h - 0.39)×K3; 2) Calculate the unit tension between the second cold rolling mill and the third cold rolling mill according to the following formula: T2 = Y×K1+(δ - 39%)×K2 - (h - 0.39)×K3; 3) Calculate the unit tension between the third cold rolling mill and the fourth cold rolling mill according to the following formula: T3 = Y×K1+(δ - 39%)×K2 - (h - 0.39)×K3 + 10; 4) Calculate the unit tension between the fourth cold rolling mill and the fifth cold rolling mill according to the following formula: T4 = Y×K1+(δ - 39%)×K2 - (h - 0.39)×K3 + 10; 5) Roll the strip steel with the tensions T1 to T4 calculated according to the above formulas 1) to 4), then there is no narrowing after the strip steel is rolled out. The present invention eliminates the narrowing defect of the 6-high 5-stand tandem cold rolling mill and ensures the dimensional accuracy of the cold-rolled strip steel product.

Description

Technical Field

[0001] The present invention relates to the technical field of cold-rolled strip steel, and particularly to a method for eliminating the width reduction defect of a 6-high 5-stand tandem cold rolling mill. Background Art

[0002] Tension rolling is an important condition for obtaining good strip shape. The reason why good strip shape can be obtained by tension rolling is that the rolled piece can be bitten into the rolls smoothly and straightly under the condition of tension, thus ensuring the consistency of the reduction rate and elongation rate of each point in the transverse direction of the strip steel.

[0003] Cold-rolled strip steel usually uses 4-high four-stand rolling mills and 6-high 5-stand rolling mills. The 4-high four-stand rolling mill has 4 rolls for each stand, including a pair of work rolls and a pair of backup rolls. The 6-high 5-stand rolling mill has 6 rolls for each stand, including a pair of work rolls, a pair of intermediate rolls, and a pair of backup rolls.

[0004] The phenomenon that the width of the strip steel is smaller after rolling by the tandem cold rolling mill than before rolling is called width reduction. At present, almost no "width reduction" occurs in the production of 4-high 4-stand rolling mills, while the proportion of steel coils with "width reduction" in the production of 6-high 5-stand rolling mills is as high as 89.39%, the average "width reduction" size is 2.87 mm, and the maximum "width reduction" size can reach 7 mm. This not only brings difficulties to the width control of the rolling and subsequent continuous annealing processes, but also seriously affects the dimensional accuracy of the cold-rolled product supply. Summary of the Invention

[0005] In order to overcome the deficiencies of the prior art, the present invention provides a method for eliminating the width reduction defect of a 6-high 5-stand tandem cold rolling mill, so as to eliminate the width reduction defect of the 6-high 5-stand tandem cold rolling mill and ensure the dimensional accuracy of the cold-rolled strip steel product.

[0006] In order to achieve the above object, the present invention is realized by adopting the following technical solutions:

[0007] A method for eliminating the width reduction defect of a 6-high 5-stand tandem cold rolling mill, wherein the 6-high 5-stand tandem cold rolling mill is composed of 5 cold rolling mills arranged in a vertical row, namely the first cold rolling mill, the second cold rolling mill, the third cold rolling mill, the fourth cold rolling mill, and the fifth cold rolling mill. Each cold rolling mill is provided with 6 rolls, which are, from the inside to the outside, a pair of work rolls, a pair of intermediate rolls, and a pair of backup rolls; the width of the strip steel is smaller after rolling by the above 6-high 5-stand tandem cold rolling mill than before rolling, which is called width reduction. Specifically, it includes:

[0008] 1) Calculate the unit tension between the first cold rolling mill and the second cold rolling mill according to the following formula:

[0009] T1 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3;

[0010] In the formula: T1 is the unit tension between the first cold rolling mill and the second cold rolling mill, N / mm 2;

[0011] Y is the yield strength of the steel, MPa;

[0012] K1 is the influence coefficient of the steel type on the yield strength Y, 0.2 - 0.4;

[0013] δ is the total reduction ratio of the rolling mill, %;

[0014] K2 is the influence coefficient of the steel type on the reduction ratio δ, 0.2 - 0.5;

[0015] K3 is the influence coefficient of the steel type on the rolling thickness h, 6.5 - 13;

[0016] h is the rolling thickness, mm;

[0017] 2) Calculate the unit tension between the second cold rolling mill and the third cold rolling mill according to the following formula:

[0018] T2 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3;

[0019] Where: T2 is the unit tension between the second cold rolling mill and the third cold rolling mill, N / mm 2 ;

[0020] Y is the yield strength of the steel, MPa;

[0021] K1 is the influence coefficient of the steel type on the yield strength Y, 0.2 - 0.4;

[0022] δ is the total reduction ratio of the rolling mill, %;

[0023] K2 is the influence coefficient of the steel type on the reduction ratio δ, 0.2 - 0.5;

[0024] K3 is the influence coefficient of the steel type on the rolling thickness h, 6.5 - 13;

[0025] h is the rolling thickness, mm;

[0026] 3) Calculate the unit tension between the third cold rolling mill and the fourth cold rolling mill according to the following formula:

[0027] T3 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3 + 10;

[0028] Where: T3 is the unit tension between the third cold rolling mill and the fourth cold rolling mill, N / mm 2 ;

[0029] Y is the yield strength of the steel, MPa;

[0030] K1 is the influence coefficient of the steel type on the yield strength Y, 0.2 - 0.4;

[0031] δ is the total reduction ratio of the rolling mill, %;

[0032] K2 is the influence coefficient of steel grade on the reduction ratio δ, 0.2 - 0.5;

[0033] K3 is the influence coefficient of steel grade on the rolling thickness h, 6.5 - 13;

[0034] h is the rolling thickness, mm;

[0035] 4) Calculate the unit tension between the fourth cold rolling mill and the fifth cold rolling mill according to the following formula:

[0036] T4 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3 + 10;

[0037] In the formula: T4 is the unit tension between the fourth cold rolling mill and the fifth cold rolling mill, N / mm 2 ;

[0038] Y is the yield strength of the steel, MPa;

[0039] K1 is the influence coefficient of steel grade on the yield strength Y, 0.2 - 04;

[0040] δ is the total reduction ratio of the rolling mill, %;

[0041] K2 is the influence coefficient of steel grade on the reduction ratio δ, 0.2 - 0.5;

[0042] K3 is the influence coefficient of steel grade on the rolling thickness h, 6.5 - 13;

[0043] h is the rolling thickness, mm;

[0044] 5) Roll the strip steel with the tensions T1 - T4 calculated according to the above formulas 1) - 4), then the strip steel will not be drawn narrower after rolling.

[0045] Furthermore, for hard steel: K1 is 0.2 - 0.3, K2 is 0.2 - 0.3, K3 is 6.5 - 8; for soft steel: K1 is 0.35 - 0.4, K2 is 0.4 - 0.5, K3 is 8.5 - 13.

[0046] Compared with the prior art, the beneficial effects of the present invention are:

[0047] The trimming width before rolling of the cold rolling mill can be sized exactly according to the width requirement of the strip steel after rolling, without having to enlarge the trimming width for sizing. Since there is no need to reserve the "narrowing" allowance for the feeding width, the annual trimming amount is reduced by 1200 tons, and the direct economic benefit is 5 - 6 million yuan.

[0048] The present invention eliminates the need for subsequent annealing processes to compensate for the "narrowing" generated during the rolling process by reducing speed and tension, and the benefit improvement is over 5 million yuan.

[0049] The present invention has been applied to actual production. The maximum "narrowing" dimension during the rolling process of a 6-high 5-stand rolling mill does not exceed 2 mm, and the non-"narrowing" rate has achieved 96.51%, generally ensuring the dimensional accuracy of the product. Detailed implementation manners

[0050] Next, in combination with the examples of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described implementation cases are only one of the embodiments of the present invention. Those skilled in the art can draw on the content of this article and appropriately improve the process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred embodiments, and those related can clearly make changes or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention.

[0051] A method for eliminating the narrowing defect of a 6-high 5-stand cold tandem rolling mill. The 6-high 5-stand cold tandem rolling mill is a longitudinally arranged 5-stand cold rolling mill, which are respectively the first cold rolling mill, the second cold rolling mill, the third cold rolling mill, the fourth cold rolling mill, and the fifth cold rolling mill. Each cold rolling mill is provided with 6 rolls, which are, from the inside to the outside, a pair of work rolls, a pair of intermediate rolls, and a pair of backup rolls; when the width of the strip steel after being rolled by the above-mentioned 6-high 5-stand cold tandem rolling mill is smaller than the width before rolling, it is called narrowing, and specifically includes:

[0052] 1) Calculate the unit tension between the first cold rolling mill and the second cold rolling mill according to the following formula:

[0053] T1 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3;

[0054] In the formula: T1 is the unit tension between the first cold rolling mill and the second cold rolling mill, N / mm 2 ;

[0055] Y is the yield strength of the steel, MPa;

[0056] K1 is the influence coefficient of the steel type on the yield strength Y, 0.2 - 0.4;

[0057] δ is the total reduction ratio of the rolling mill, %;

[0058] K2 is the influence coefficient of the steel type on the reduction ratio δ, 0.2 - 0.5;

[0059] K3 is the influence coefficient of the steel type on the rolling thickness h, 6.5 - 13;

[0060] h is the rolling thickness, in mm;

[0061] 2) Calculate the unit tension between the second cold rolling mill and the third cold rolling mill according to the following formula:

[0062] T2 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3;

[0063] In the formula: T2 is the unit tension between the second cold rolling mill and the third cold rolling mill, in N / mm 2 ;

[0064] Y is the yield strength of the steel, in MPa;

[0065] K1 is the influence coefficient of the steel type on the yield strength Y, 0.2 - 04;

[0066] δ is the total reduction ratio of the rolling mill, in %;

[0067] K2 is the influence coefficient of the steel type on the reduction ratio δ, 0.2 - 0.5;

[0068] K3 is the influence coefficient of the steel type on the rolling thickness h, 6.5 - 13;

[0069] h is the rolling thickness, in mm;

[0070] 3) Calculate the unit tension between the third cold rolling mill and the fourth cold rolling mill according to the following formula:

[0071] T3 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3 + 10;

[0072] In the formula: T3 is the unit tension between the third cold rolling mill and the fourth cold rolling mill, in N / mm 2 ;

[0073] Y is the yield strength of the steel, in MPa;

[0074] K1 is the influence coefficient of the steel type on the yield strength Y, 0.2 - 04;

[0075] δ is the total reduction ratio of the rolling mill, in %;

[0076] K2 is the influence coefficient of the steel type on the reduction ratio δ, 0.2 - 0.5;

[0077] K3 is the influence coefficient of the steel type on the rolling thickness h, 6.5 - 13;

[0078] h is the rolling thickness, in mm;

[0079] 4) Calculate the unit tension between the fourth cold rolling mill and the fifth cold rolling mill according to the following formula:

[0080] T4 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3 + 10;

[0081] Where: T4 is the unit tension between the fourth cold rolling mill and the fifth cold rolling mill, N / mm 2 ;

[0082] Y is the yield strength of the steel, MPa;

[0083] K1 is the influence coefficient of the steel type on the yield strength Y, 0.2 - 0.4;

[0084] δ is the total reduction ratio of the rolling mill, %;

[0085] K2 is the influence coefficient of the steel type on the reduction ratio δ, 0.2 - 0.5;

[0086] K3 is the influence coefficient of the steel type on the rolling thickness h, 6.5 - 13;

[0087] h is the rolling thickness, mm;

[0088] 5) When the strip steel is rolled with the tensions T1 - T4 calculated according to the above calculation formulas 1) - 4), the strip steel will not be drawn narrower after rolling.

[0089] Furthermore, for hard steel types: K1 is 0.2 - 0.3, K2 is 0.2 - 0.3, K3 is 6.5 - 8; for soft steel types: K1 is 0.35 - 0.4, K2 is 0.4 - 0.5, K3 is 8.5 - 13.

[0090] K1 - K3 values of related steel types

[0091]

[0092]

[0093] The overall technical idea of the present invention

[0094] I. Through analysis, it is determined that the reasons for the "drawing narrower" of the 6 - high 5 - stand rolling mill are as follows:

[0095] 1. Since the 6 - high 5 - stand rolling mill has one more pair of intermediate rolls than the 4 - high 4 - stand rolling mill, the stiffness of the rolling mill increases and the diameter of the work roll becomes smaller, making the hindrance to the longitudinal extension of the rolled piece during the rolling process smaller compared to the 4 - high 4 - stand rolling mill.

[0096] 2. Since the 6 - high 5 - stand rolling mill has one more rolling mill than the 4 - high 4 - stand rolling mill, the reduction ratio allocated to each rolling mill becomes smaller, making the hindrance to the longitudinal extension of the rolled piece during the rolling process smaller compared to the 4 - high 4 - stand rolling mill.

[0097] 3. Since the six-high five-stand rolling mill has one more pass of stretching than the four-high four-stand rolling mill, the total tension borne by the rolled piece during rolling increases relative to that of the four-high four-stand rolling mill.

[0098] II. Determine the overall method for eliminating the "narrowing" in the six-high five-stand rolling mill

[0099] Through analysis, it is determined that the overall method for eliminating the "narrowing" in the six-high five-stand rolling mill is to reduce the tension between the rolling mill stands during the rolling process of the rolled piece. The so-called tension is the force that tightens the strip during the rolling process, and the magnitude of the tension is determined by the rotational speed difference between the front and rear two rolling mills.

[0100] III. Determine the relevant variables affecting the setting of the tension value

[0101] The variables affecting the setting of the tension value are:

[0102] 1. The yield strength of the material. It represents the ability of the material to resist deformation. The unit is Mpa.

[0103] 2. The total reduction ratio. (Thickness of the rolled piece before rolling - Thickness of the rolled piece after rolling) ÷ Thickness of the rolled piece before rolling. The unit is %.

[0104] 3. The rolling thickness. The thickness of the rolled piece after rolling. The unit is mm.

[0105] 4. The steel grade. Different steel grades result from different chemical compositions and ratios of the material.

[0106] IV. Establish a tension calculation formula

[0107] Establish a tension calculation formula based on the influence relationship of relevant variables on the setting of the tension value.

[0108] The steps for establishing the tension calculation formula of the present invention are as follows:

[0109] I. Determine the influence of the yield strength of the material on the setting of the tension value

[0110] The yield strength Y. When the yield strength of the material is relatively large, the ability of the material to resist deformation is also relatively large, so the tension setting should be relatively large; when the yield strength of the material is relatively small, the ability of the material to resist deformation is also relatively small, so the tension setting should be relatively small.

[0111] II. Determine the influence of the reduction ratio on the setting of the tension value

[0112] The reduction ratio δ. When the reduction ratio is relatively large, the resistance to the longitudinal extension of the strip is relatively large, so the tension setting should be relatively large; when the reduction ratio is relatively small, the resistance to the longitudinal extension of the strip is relatively small, so the tension setting should be relatively small.

[0113] III. Determine the influence of the rolling thickness on the tension setting

[0114] Rolling thickness h. When the rolling thickness is large, the hindrance to the longitudinal extension of the strip steel is relatively small, so the tension setting should be relatively small; when the rolling thickness is small, the hindrance to the longitudinal extension of the strip steel is relatively large, so the tension setting should be relatively large.

[0115] IV. Determine the basic relationship between the tension value calculation and each variable

[0116] T = Y + (δ - 39%) - (h - 0.39)

[0117] In the formula, T is the strip steel tension, unit N / mm 2 .

[0118] In the formula, Y is the yield strength, unit Mpa.

[0119] δ is the reduction ratio, unit %.

[0120] h is the strip steel thickness, unit mm.

[0121] (δ - 39%) in 39% is the minimum reduction ratio specified in the rolling schedule, and the reduction ratio is reduced through (δ - 39%)

[0122] The influence on the tension value setting.

[0123] (h - 0.39) in 0.39 is the minimum rolling thickness specified in the rolling schedule, and the influence of the rolling thickness on the tension value setting is reduced through (h - 0.39).

[0124] V. Determine the influence coefficient of different steel grades on variable Y

[0125] For different steel grades, the friction coefficients are different, and the hindrance to the longitudinal extension of the rolling mill during the rolling process is different, and the influence coefficients on each variable affecting the tension value setting are also different. The influence relationship of the steel grade on variable Y is Y × K1. K1 represents the influence coefficient of different steel grades on Y. The range of K1 value: 0.2 - 0.4.

[0126] VI. Determine the influence coefficient of different steel grades on variable (δ - 39%)

[0127] For different steel grades, the influence coefficients on variable (δ - 39%) are different. The influence relationship of the steel grade on variable (δ - 39%) is Y × K2. K2 represents the influence coefficient of different steel grades on (δ - 39%). The range of K2 value: 0.2 - 0.5.

[0128] VII. Determine the influence coefficient of different steel grades on variable (h - 0.39)

[0129] For different steel grades, the influence coefficients on the variable (h - 0.39) are different. The influence relationship of the steel grade on the variable (h - 0.39) is Y × K3. K3 represents the influence coefficient of different steel grades on (h - 0.39). The range of the K3 value is 6.5 - 13.

[0130] VIII. Determine the general form of the tension calculation formula between the stands of the reversing mill

[0131] 1. Tension calculation formula between stands 1 - 2: T1 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3.

[0132] 2. Tension calculation formula between stands 2 - 3: T2 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3.

[0133] 3. Tension calculation formula between stands 3 - 4: T3 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3 + 10.

[0134] 4. Tension calculation formula between stands 4 - 5: T4 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3 + 10.

[0135] Calculate the strip tension between each stand according to the above formula, and the "narrowing" of the strip width at the exit of the rolling mill is 0. In the formula

[0136] T1 - T4: The unit tension between each stand. Unit: MPa.

[0137] δ: The total reduction ratio of the rolling mill, unit: %.

[0138] H: The thickness of the strip at the exit of the last stand of the rolling mill. Unit: mm.

[0139] K1: The influence coefficient of the steel grade on the yield strength Y.

[0140] K2: The influence coefficient of the steel grade on the reduction ratio δ.

[0141] K3: The influence coefficient of the steel grade on the rolling thickness h.

[0142] IX. Determine the tension calculation formula for each steel grade

[0143] For accurate calculation, it is necessary to determine the influence coefficients of each steel grade on various variables. Therefore, each steel grade has a corresponding calculation formula for setting the tension value.

[0144] Example 1:

[0145] Known relevant variables: Steel grade DC53D, short grade DC53JD, yield strength 245 Mpa, total reduction rate 80%, rolling thickness 0.78. Correlation coefficient K1 is 0.37; K2 is 0.4; K3 is 13.5.

[0146] 1) Calculate the tension between the first cold rolling mill and the second cold rolling mill:

[0147] T1 = Y × 0.37 + (δ - 39%) × 0.4 - (H - 0.39) × 13.5

[0148] = 245 × 0.37 + (80% - 39%) × 0.4 - (0.78 - 0.39) × 13.5

[0149] = 90.65 MPa + 0.164 - 5.265 = 86.55 N / mm 2 .

[0150] 2) Calculate the tension between the second cold rolling mill and the third cold rolling mill:

[0151] T2 = Y × 0.37 + (δ - 39%) × 0.4 - (H - 0.39) × 13.5

[0152] = 245 × 0.37 + (80% - 39%) × 0.4 - (0.78 - 0.39) × 13.5

[0153] = 90.65 MPa + 0.164 - 5.265 = 86.55 N / mm 2 .

[0154] 3) Calculate the tension between the fourth cold rolling mill and the fifth cold rolling mill:

[0155] T3 = Y × 0.37 + (δ - 39%) × 0.4 - (H - 0.39) × 13.5 + 10

[0156] = 245 × 0.37 + (80% - 39%) × 0.4 - (0.78 - 0.39) × 13.5 + 10

[0157] = 90.65 MPa + 0.164 - 5.265 + 10 = 96.55 N / mm 2 .

[0158] 4) Calculate the tension between the fifth cold rolling mill and the sixth cold rolling mill:

[0159] T4 = Y × 0.37 + (δ - 39%) × 0.4 - (H - 0.39) × 13.5 + 10

[0160] = 245 × 0.37 + (80% - 39%) × 0.4 - (0.78 - 0.39) × 13.5 + 10

[0161] = 90.65 MPa + 0.164 - 5.265 + 10 = 96.55 N / mm 2 。

[0162] The amount of narrowing = 0 mm

[0163] Under the same conditions of material yield strength, steel type, rolling thickness and reduction ratio, the tension setting value of the prior art is

[0164] T1 = 110 MPa, 23.45 N / mm higher than that of the present invention 2

[0165] T2 = 110 MPa; 23.45 N / mm higher than that of the present invention 2

[0166] T3 = 120 MPa; 33.45 N / mm higher than that of the present invention 2

[0167] T4 = 130 MPa; 33.45 N / mm higher than that of the present invention 2

[0168] The measured amount of narrowing = 5 mm

[0169] Example 2:

[0170] Known relevant variables: low-alloy high-strength steel, short grade CQ340V, yield strength 325 Mpa, total reduction ratio 56%, rolling thickness 1.98. The correlation coefficient K1 is 0.28; K2 is 0.4; K3 is 11.5.

[0171] 1) Calculate the tension between the first cold rolling mill and the second cold rolling mill:

[0172] T1 = Y × 0.28 + (δ - 39%) × 0.4 - (H - 0.39 × 11.5

[0173] = 325 × 0.28 + (56% - 39%) × 0.4 - (1.98 - 0.39) × 11.5

[0174] = 91 MPa + 0.17 - 18.28 = 72.92 N / mm 2 。

[0175] 2) Calculate the tension between the second cold rolling mill and the third cold rolling mill:

[0176] T2 = Y × 0.28 + (δ - 39%) × 0.4 - (H - 0.39) × 11.5

[0177] = 325 × 0.28 + (56.% - 39%) × 0.4 - (1.98 - 0.39) × 11.5

[0178] = 91 MPa + 0.17 - 18.28 = 72.92 N / mm 2 。

[0179] 3) Calculate the tension between the fourth cold rolling mill and the fifth cold rolling mill:

[0180] T3 = Y × 0.28 + (δ - 39%) × 0.4 - (H - 0.39) × 11.5 + 10

[0181] = 325 × 0.28 + (56.% - 39%) × 0.4 - (1.98 - 0.39) × 11.5 + 10

[0182] = 91 MPa + 0.17 - 18.28 + 10 = 82.92 N / mm 2 。

[0183] 4) Calculate the tension between the fifth cold rolling mill and the sixth cold rolling mill:

[0184] T4 = Y × 0.28 + (δ - 39%) × 0.4 - (H - 0.39) × 11.5 + 10

[0185] = 325 × 0.28 + (56.% - 39%) × 0.4 - (1.98 - 0.39) × 11.5 + 10

[0186] = 91 MPa + 0.17 - 18.28 + 10 = 82.92 N / mm 2 。

[0187] The measured narrowing amount = 0

[0188] Under the same conditions of material yield strength, steel type, rolling thickness and reduction ratio, the tension setting value of the prior art is

[0189] T1 = 70 MPa, which is 2.92 N / mm smaller than that of the present invention 2

[0190] T2 = 80 MPa; which is 7.08 N / mm higher than that of the present invention 2

[0191] T3 = 90 MPa; which is 17.08 N / mm higher than that of the present invention 2

[0192] T4 = 90 MPa; which is 17.08 N / mm higher than that of the present invention 2

[0193] Measured narrowing amount = 2mm

[0194] Example 3:

[0195] Known relevant variables: DC04E, short grade CR3-D, yield strength 221 Mpa, total reduction ratio 63.99%, rolling thickness 1.98, correlation coefficient K1 is 0.4; K2 is 0.4; K3 is 8.5.

[0196] 1) Calculate the tension between the first cold rolling mill and the second cold rolling mill:

[0197] T1 = Y × 0.4 + (δ - 39%) × 0.4 - (H - 0.39) × 8.5

[0198] = 221 × 0.4 + (63.99% - 39%) × 0.4 - (1.98 - 0.39) × 8.5

[0199] = 88.4 N / mm 2 + 0.9996 - 8.5 = 75.87 N / mm 2 .

[0200] 2) Calculate the tension between the second cold rolling mill and the third cold rolling mill:

[0201] Y × 0.4 + (δ - 39%) × 0.4 - (H - 0.39) × 8.5

[0202] = 221 × 0.4 + (63.99% - 39%) × 0.4 - (1.98 - 0.39) × 8.5

[0203] = 88.4 N / mm 2 + 0.9996 - 8.5 = 75.87 N / mm 2 .

[0204] 3) Calculate the tension between the fourth cold rolling mill and the fifth cold rolling mill:

[0205] T3 = Y × 0.4 + (δ - 39%) × 0.4 - (H - 0.39) × 8.5 + 10

[0206] = 221 × 0.4 + (63.99% - 39%) × 0.4 - (1.98 - 0.39) × 8.5 + 10

[0207] = 88.4 N / mm 2 + 0.9996 - 8.5 = 85.87 N / mm 2 .

[0208] 4) Calculate the tension between the fifth cold rolling mill and the sixth cold rolling mill:

[0209] T4 = Y × 0.4 + (δ - 39%) × 0.4 - (H - 0.39) × 8.5 + 10

[0210] = 221 × 0.4 + (63.99% - 39%) × 0.4 - (1.98 - 0.39) × 8.5 + 10

[0211] = 88.4 N / mm 2 + 0.9996 - 8.5 = 85.87 N / mm 2 。

[0212] Measured narrowing amount = 0

[0213] Under the same conditions of material yield strength, steel type, rolling thickness and reduction ratio, the tension setting value of the prior art is

[0214] T1 = 80 MPa, 4.13 N / mm higher than that of the present invention 2

[0215] T2 = 80 MPa; 4.13 N / mm higher than that of the present invention 2

[0216] T3 = 90 MPa; 14.13 N / mm higher than that of the present invention 2

[0217] T4 = 90 MPa; 14.13 N / mm higher than that of the present invention 2

[0218] Measured narrowing amount = 2 mm

[0219] Table 1 shows the narrowing data obtained by rolling with the present invention

[0220]

[0221] It can be seen from Table 1 that the total number of verified rolling coils is 656, the number of coils with "narrowing" is 27, accounting for 4.43%, and the maximum "narrowing" amount is 2 mm. The present invention eliminates the narrowing defect of the six-high five-stand cold tandem mill and ensures the dimensional accuracy of cold-rolled strip products.

[0222] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A method for eliminating the defect of width reduction in a 6-high 5-stand tandem cold rolling mill. The 6-high 5-stand tandem cold rolling mill has 5 cold rolling mills arranged in a vertical column, namely the first cold rolling mill, the second cold rolling mill, the third cold rolling mill, the fourth cold rolling mill, and the fifth cold rolling mill. Each cold rolling mill is equipped with 6 rolls, which are, from the inside to the outside, a pair of work rolls, a pair of intermediate rolls, and a pair of backup rolls. When the strip steel is rolled by the above-mentioned 6-high 5-stand tandem cold rolling mill and its width is smaller than the width before rolling, it is called width reduction. The method is characterized in that, Specifically include: 1) Calculate the unit tension between the first cold rolling mill and the second cold rolling mill according to the following formula: T1 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3; Where: T1 is the unit tension between the first cold rolling mill and the second cold rolling mill, N / mm 2 ; 2) Calculate the unit tension between the second cold rolling mill and the third cold rolling mill according to the following formula: T2 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3; Where: T2 is the unit tension between the second cold rolling mill and the third cold rolling mill, N / mm 2 ; 3) Calculate the unit tension between the third cold rolling mill and the fourth cold rolling mill according to the following formula: T3 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3 + 10; Where: T3 is the unit tension between the third cold rolling mill and the fourth cold rolling mill, N / mm 2 ; 4) Calculate the unit tension between the fourth cold rolling mill and the fifth cold rolling mill according to the following formula: T4 = Y × K1 + (δ - 39%) × K2 - (h - 0.39) × K3 + 10; Where: T4 is the unit tension between the fourth cold rolling mill and the fifth cold rolling mill, N / mm 2 ; Y is the yield strength of the steel, MPa; K1 is the influence coefficient of the steel type on the yield strength Y, 0.2 - 0.4; δ is the total reduction ratio of the rolling mill, %; K2 is the influence coefficient of the steel type on the reduction ratio δ, 0.2 - 0.5; K3 is the influence coefficient of the steel type on the rolling thickness h, 6.5 - 13; h is the rolling thickness, mm; 5) Roll the strip steel with tensions T1 - T4 calculated according to the above calculation formulas 1) - 4).

2. A method for eliminating the width reduction defect of a six-high five-stand cold tandem rolling mill according to claim 1, characterized in that, For hard steel types: K1 is 0.2 - 0.3, K2 is 0.2 - 0.3, K3 is 6.5 - 8; for soft steel types: K1 is 0.35 - 0.4, K2 is 0.4 - 0.5, K3 is 8.5 - 13.

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