Roll shape of intermediate roll of SmartCrown cold-rolling mill and design method of roll shape

Abstract

The invention discloses a Smart Crown cold-rolling mill intermediate roll shape and a design method thereof, and belongs to the technical field of cold-rolled sheet strip steel production. According to the method, values of a, b, c and phi are randomly selected within a parameter range according to setting of boundary conditions, optimal values of a, b, c and phi are calculated according to the maximum roll gap adjustment value and the minimum inter-roll pressure difference of an objective function, and therefore the optimal roll type of the intermediate roll of the Smart Crown cold rolling mill is obtained. According to the method, an optimization algorithm is combined with a load roll gap shape calculation model, elastic deformation of the roll in a load state is fully considered, the method is more suitable for actual production, and the purpose of improving the strip steel plate shape quality can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of cold-rolled plate and strip steel production, and in particular to a SmartCrown cold rolling mill intermediate roll profile and a design method thereof. Background Art

[0002] During the cold rolling process, the rolls are in direct contact with the strip, so the original roll shape design is one of the important means of controlling the shape of the cold rolled strip. SmartCrown is a new type of shape control technology, and its unique advantage is that it can locally control the sensitive areas of the two rib wave areas. SmartCrown roll shape is a pair of "vase" rolls with S curves ( Figure 1 ), the continuous adjustment of the roll gap convexity is achieved through the lateral movement of the roll, and the roll profile curve expression is shown in formula (1):

[0003]

[0004] Where x is the roll unit coordinate, mm; y is u (x) is the roller profile curve expression of the upper roller; y b (x) is the roller profile curve expression of the lower roller; L is the roller length, mm; a, b, c, Φ are the roller profile parameters to be determined. Determining the optimal roller profile parameters a, b, c, Φ is the key to designing the SmartCrown roller profile.

[0005] The invention patent with application number 201911301514.X discloses "a working roll profile design method capable of reducing axial force". This method reduces axial force by optimizing roll profile curve parameters. However, the method only considers the shape of the no-load roll profile curve, and the roll often undergoes large elastic deformation under the action of rolling force. Therefore, there is room for further optimization of this method.

[0006] The invention patent with application number 200910074430.7 discloses a "roller curve design method for four-roll cold rolling mill with the goal of preventing and controlling compound waves". This method achieves the purpose of alleviating compound waves by optimizing the curve equations of the working roll and the support roll. However, this method is only applicable to four-roll mills, not to six-roll SmartCrown mills. This method also does not consider the changes in the roll gap after loading, so the optimization effect needs to be improved.

[0007] It can be seen from the above literature that most roll shape optimization methods do not consider the roll gap shape after loading, and the optimization effect needs to be further improved. It is urgent to propose an optimization method that considers the roll gap after loading and is applicable to the roll shape of the six-roll SmartCrown intermediate roll to improve the plate shape quality. Summary of the invention

[0008] In view of the problems existing in the prior art, the present invention provides a SmartCrown cold rolling mill intermediate roll profile and a design method thereof. The present invention is applied to the SmartCrown cold rolling mill production line, and the purpose of improving the strip shape quality is achieved by combining the optimization algorithm with the load roll gap shape calculation model.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0010] A method for designing a roll profile of an intermediate roll of a SmartCrown cold rolling mill according to the present invention comprises the following steps:

[0011] Step 1: Based on the influence function method, a calculation model for the elastic deformation of the roller in the lateral unit coordinates of the roller under load is established.

[0012] Among them, the calculation model of the roller elastic deformation of the roller transverse unit coordinate under load is shown in formula (2):

[0013]

[0014] Where i, j are the transverse units of the roller; n is the total number of transverse units of the roller; y(i) is the elastic deformation of the i-th unit under load, mm; y0(i,j) is the deformation of the i-th unit under the influence of the force on the j-th unit; g(i,j) is the influence function of the force on the j-th unit on the i-th unit; p(j) is the force on the j-th unit, N.

[0015] In the step 1, p(j) is determined by rolling process parameters.

[0016] Step 2: Setting boundary conditions. In order to avoid excessive roller diameter difference, the roller parameters a, b, c and Φ should be kept within the range of formula (3):

[0017]

[0018] A set of roll profile parameters is randomly formed within the range of formula (3), and is substituted into formula (1) to obtain the roll transverse unit corresponding to x, which is j, y u (j) and y b (j);

[0019] Step 3: Combine formula (1) and calculate the load roller gap shape g(i) according to formula (4):

[0020] g(i)=(-y u (i)+y(i))-(y b (i)+y(i)) (4)

[0021] Where: y u (i) is the roller profile curve expression of the upper roller, mm; y b(i) is the roller profile curve expression of the lower roller, mm; y(i) is the elastic deformation of the i-th unit under load, mm; g(i) is the load roller gap shape, mm.

[0022] Step 4: Combine equations (5) and (6) to optimize and determine the objective function. In order to improve the plate shape control capability of the rolling mill, the adjustment range of the roll gap should be as large as possible, and the roll gap adjustment range objective function J1 is shown in equation (5):

[0023]

[0024] Where N is the number of roll units; g(N / 2) is the roll gap value at the roll center, mm; g(0) is the roll gap value at the roll end, mm; J1 is the roll gap adjustment range objective function.

[0025] The uneven contact pressure between the rolls will affect the service life of the rolls and increase the difficulty of strip shape control. Therefore, the objective function of the pressure between the rolls J2 is shown in formula (6):

[0026] J2=min(QWI max -QWI min ) (6)

[0027] Where QWI max The maximum contact pressure between the intermediate roll and the working roll, N; QWI min is the minimum contact pressure between the intermediate roll and the working roll, N; J2 is the target function of the pressure between the rolls; QWI max and QWI min Calculated using the influence function method.

[0028] Step 5: The roll elastic deformation calculation model and the load roll gap calculation process are embedded in the genetic algorithm, and the roll profile parameters a, b, c and Φ are optimized by multiple objectives to find the optimal solution of a, b, c and Φ, thereby obtaining the roll profile curve expression and the optimal SmartCrown cold rolling mill intermediate roll profile.

[0029] The design process of the intermediate roll of SmartCrown cold rolling mill is as follows: Figure 2 As shown; specifically: according to the boundary conditions of formula (3), the values ​​of a, b, c and Φ are randomly selected within the parameter range. According to the objective function, the roll gap adjustment value is maximized and the pressure difference between the rolls is minimized. It is calculated whether the objective function value satisfies the evolutionary algebra of 100. If not, the values ​​of a, b, c and Φ are cross-adjusted for re-judgment. If satisfied, the values ​​of a, b, c and Φ are output as the optimal values. According to formula (1), the roll profile curve expression is obtained, and the optimal SmartCrown cold rolling mill intermediate roll profile is obtained.

[0030] The roll profile of an intermediate roll of a SmartCrown cold rolling mill of the present invention is designed by adopting the above-mentioned design method and is applied to a SmartCrown cold rolling mill production line.

[0031] Compared with the prior art, the SmartCrown cold rolling mill intermediate roll profile and design method thereof described in the present invention fully consider the elastic deformation of the roll under load, are more suitable for actual production, and can achieve the purpose of improving the strip shape quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is the SmartCrown roller profile curve.

[0033] Figure 2 Flow chart for the roll profile design process. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with embodiments.

[0035] The embodiment of the present invention is carried out on a six-roll Smartcrown cold rolling mill, and the basic parameters of the rolling mill are: working roll diameter: 280-330 mm; intermediate roll diameter: 540-580 mm; support roll diameter: 1320-1460 mm.

[0036] Example 1

[0037] Prepare DP590 hot-rolled pickled plate with a thickness of 3.0 mm and a width of 1250 mm:

[0038] Step 1: A set of roll profile parameters are randomly generated within the boundary conditions of formula (3), namely a=3.1, b=0.0038, c=77, and Φ=1.17. The forces p(j) and g(i,j) on each lateral unit are calculated according to the rolling process parameters in Table 1, and then the forces p(j) and g(i,j) on each lateral unit are substituted into formula (2). Based on the influence function method, the roll elastic deformation y(i) of each lateral unit coordinate of the roll under load is calculated.

[0039] Table 1 Rolling process parameters in Example 1

[0040]

[0041] Step 2: According to the contact width between the roller and the strip of 1250mm, the width of a roll gap unit is 41.67mm, then the center coordinates of the first unit are 41.67 / 2=20.835, the center coordinates of the second unit are 20.835+41.67=62.505, ..., and the corresponding calculation of y u (20.835) corresponds to y u (1) y u (62.505) corresponds to yu (2), ..., y u (1229.265) corresponds to y u (30), the corresponding y b (20.835) corresponds to y b (1) y b (62.505) corresponds to y b (2), ..., y b (1229.265) corresponds to y b (30), calculate the corresponding y u (j) and y b (j); Calculate the load roller gap shape g(i) according to formula (4). The values ​​of the load roller gap shape are shown in Table 2.

[0042] Table 2 Calculated values ​​of roll gap shape, mm

[0043] Roll gap unit Load roll gap shape Roll gap unit Load roll gap shape Roll gap unit Load roll gap shape 1 -0.2802 11 0.1612 21 1.1070 2 -0.2754 12 0.2452 22 1.1982 3 -0.2612 13 0.3338 23 1.2852 4 -0.2376 14 0.4263 24 1.3672 5 -0.2048 15 0.5218 25 1.4436 6 -0.1632 16 0.6194 26 1.5134 7 -0.1132 17 0.7181 27 1.5762 8 -0.0551 18 0.8172 28 1.6314 9 0.0104 19 0.9157 29 1.6784 10 0.0827 20 1.0126 30 1.7168

[0044] Step 3: According to the objective functions of formula (5) and formula (6), the optimal values ​​of the roll profile parameters are determined as follows: a=3.872, b=0.0048, c=75, Φ=1.425; the parameters are substituted into formula (1) to obtain the roll profile curve expression, and the optimal SmartCrown cold rolling mill intermediate roll profile is obtained.

[0045] Example 2

[0046] Prepare HSLA hot-rolled pickled plate with a thickness of 4.0 mm and a width of 1050 mm:

[0047] Step 1: A set of roll profile parameters are randomly generated within the boundary conditions of formula (3): a = 3.5, b = 0.0045, c = 90, Φ = 2.25. The forces p(j) and g(i, j) on each lateral unit are calculated according to the rolling process parameters in Table 3, and then substituted into formula (2). The elastic deformation of each lateral unit of the roller is calculated based on the influence function method.

[0048] Table 3 Rolling process parameters in Example 1

[0049]

[0050] Step 2: Based on the contact width between the roller and the strip of 1050 mm and the width of a roll gap unit of 35 mm, calculate the corresponding y u (j) and y b (j), the load roll gap shape g(i) is calculated according to formula (4), and the roll gap value of the load roll gap shape is shown in Table 4.

[0051] Table 4 Calculated values ​​of roll gap shape, mm

[0052] Roll gap unit Load roll gap shape Roll gap unit Load roll gap shape Roll gap unit Load roll gap shape 1 -0.8798 11 0.3383 21 2.1838 2 -0.8658 12 0.5491 22 2.2783 3 -0.8238 13 0.7635 23 2.3468 4 -0.7547 14 0.9778 24 2.3881 5 -0.6596 15 1.1884 25 2.4014 6 -0.5401 16 1.3917 26 2.3867 7 -0.3984 17 1.5842 27 2.3441 8 -0.2367 18 1.7625 28 2.2743 9 -0.0579 19 1.9237 29 2.1785 10 0.1348 20 2.0649 30 2.0585

[0053] Step 3: According to the objective functions of formula (5) and formula (6), the optimal values ​​of the roll profile parameters are determined as follows: a=4.0124, b=0.0039, c=57, Φ=2.234; Substitute the parameters into formula (1) to obtain the roll profile curve expression and obtain the optimal SmartCrown cold rolling mill intermediate roll profile.

[0054] Example 3

[0055] Prepare Q235 hot-rolled pickled plate with a thickness of 2.5mm and a width of 950mm:

[0056] Step 1: A set of roll profile parameters are randomly generated within the boundary conditions of formula (3): a = 4.1, b = 0.0032, c = 45, Φ = 3.0. The forces p(j) and g(i, j) on each lateral unit are calculated according to the rolling process parameters in Table 5, and then substituted into formula (2). The elastic deformation of each lateral unit of the roller is calculated based on the influence function method.

[0057] Table 5 Rolling process parameters in Example 1

[0058]

[0059] Step 2: Based on the contact width between the roller and the strip of 950 mm and the width of a roll gap unit of 31.67 mm, calculate the corresponding y u (j) and y b (j), the load roll gap shape g(i) is calculated according to formula (4), and the roll gap value of the load roll gap shape is shown in Table 6.

[0060] Table 6 Calculated values ​​of roll gap shape, mm

[0061]

[0062]

[0063] Step 3: According to the objective functions of formula (5) and formula (6), the optimal values ​​of the roll profile parameters are determined as follows: a=3.15, b=0.0031, c=46, Φ=3.015. According to formula (1), the roll profile curve expression is obtained, and the optimal SmartCrown cold rolling mill intermediate roll profile is obtained.

[0064] Verification Example

[0065] The plate quality is evaluated by the measurement results of the plate shape meter on the production line. The higher the IU value, the worse the plate quality. The average plate shape value of the cold-rolled plate strip is 9IU when the intermediate roll profile designed for the no-load roll profile is used for cold-rolling the plate strip.

[0066] The intermediate roll profile designed by the present invention is used to cold-roll steel strips, and the average shape value of the cold-rolled steel strips is 5IU. The comparison shows that the present invention takes into account the change of the roll gap after load, and the optimized result can improve the shape quality of the cold-rolled steel strips.

Claims

1. A design method for the profile of an intermediate roll of a SmartCrown cold rolling mill, characterized in that: The design method of the roll profile of the intermediate roll of the SmartCrown cold rolling mill is as follows: according to the setting of boundary conditions, the values ​​of a, b, c and Φ are randomly selected within the parameter range; according to the objective function, the roll gap adjustment value is maximized and the pressure difference between the rolls is minimized; whether the objective function value satisfies the evolution algebra reaching 100 is calculated; if not, the values ​​of a, b, c and Φ are cross-adjusted for re-judgment; if satisfied, the values ​​of a, b, c and Φ are output as the optimal values; according to the roll profile curve expression, the roll profile curve expression is obtained to obtain the optimal SmartCrown cold rolling mill intermediate roll profile.

2. The design method of the intermediate roll profile of the SmartCrown cold rolling mill according to claim 1, characterized in that: The roller profile curve is expressed as the following formula (1): Where x is the roll unit coordinate, mm; y is u (x) is the roller profile curve expression of the upper roller; y b (x) is the roller profile curve expression of the lower roller; L is the roller body length, mm; a, b, c, Φ are the roller profile parameters to be determined.

3. A design method for the intermediate roll profile of a SmartCrown cold rolling mill, characterized in that: The following steps are involved: S1. Based on the influence function method, a calculation model of roller elastic deformation of roller transverse unit coordinates under load state is established; S2. Setting of boundary conditions: Roller parameters a, b, c and Φ must be kept within the range of the following formula (3): Randomly select the values ​​of a, b, c and Φ in the above range to form a set of roll curve parameters, and substitute them into the roll curve expression to obtain the y corresponding to the roll transverse unit j of x. u (j) and y b (j); S3, combined with the roller elastic deformation calculation model and y determined by S2 u (j) and y b (j), calculate the load roller gap shape g(i) according to the following formula (4): g(i)=(-y u (i)+y(i))-(y b (i)+y(i)) (4) Where: y u (i) is the roller profile curve expression of the upper roller, mm; y b (i) is the roller profile curve expression of the lower roller, mm; y(i) is the elastic deformation of the i-th unit under load, mm; g(i) is the load roller gap shape, mm; S4. Optimize the maximum roll gap adjustment value and the minimum pressure difference between the rolls to determine the objective function; the roll gap adjustment range objective function J1 with the maximum roll gap adjustment value is as shown in formula (5): Where, N is the number of roll units; g(N / 2) is the roll gap value at the roll center, mm; g(0) is the roll gap value at the roll end, mm; J1 is the roll gap adjustment range objective function; The inter-roller pressure objective function J2 with the minimum inter-roller pressure difference is shown in formula (6): J2=min(QWI max -QWI min ) (6) Where QWI max The maximum contact pressure between the intermediate roll and the working roll, N; QWI min is the minimum contact pressure between the intermediate roll and the working roll, N; J2 is the target function of the pressure between the rolls; QWI max and QWI min Calculated according to the influence function method; S5. The roll elastic deformation calculation model and the load roll gap calculation process are embedded in the genetic algorithm, and the roll profile parameters a, b, c and Φ are optimized by multiple objectives to find the optimal solution of a, b, c and Φ, thereby obtaining the roll profile curve expression and the optimal SmartCrown cold rolling mill intermediate roll profile.

4. The method for designing the profile of the intermediate roll of the SmartCrown cold rolling mill according to claim 3, characterized in that: The calculation model of the roller elastic deformation of the roller transverse unit coordinates under load is shown in formula (2): Where i, j are the transverse units of the roller; n is the total number of transverse units of the roller; y(i) is the elastic deformation of the i-th unit under load, mm; y0(i,j) is the deformation of the i-th unit under the influence of the force on the j-th unit; g(i,j) is the influence function of the force on the j-th unit on the i-th unit; p(j) is the force on the j-th unit, N.

5. The design method of the intermediate roll profile of the SmartCrown cold rolling mill according to claim 4, characterized in that: The p(j) is determined by rolling process parameters.

6. The method for designing the profile of the intermediate roll of the SmartCrown cold rolling mill according to claim 4, characterized in that: The roller profile curve expression is shown in formula (1): Where x is the roll unit coordinate, mm; y is u (x) is the roller profile curve expression of the upper roller; y b (x) is the roller profile curve expression of the lower roller; L is the roller body length, mm; a, b, c, Φ are the roller profile parameters to be determined.

7. A SmartCrown cold rolling mill intermediate roll profile, designed by the design method according to any one of claims 1 to 6.

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