Hot-rolled plate shape optimization method considering roll shape curve of working roll

Abstract

The invention belongs to the technical field of hot rolling, and particularly relates to a hot-rolled plate shape optimization method considering a roll shape curve of a working roll, which comprises the following calculation and analysis steps: a) inquiring key process and equipment parameters; b) giving product steel grade and specification characteristics; c) assigning initial values to the parameters in the calculation process; d) establishing a plate shape optimization objective function; e) giving the lowest point ymin of the initial concave roller curve of the working roller; f) calculating initial plate shape convexity distribution; g) changing the value of the lowest point ymin of the concave roller curve of the working roller; h) fitting and calculating a roll shape curve of the working roll; i) calculating and optimizing profile convexity distribution; j) judging conditions of an advance and retreat method; and k) outputting the final roll shape curve of the working roll. According to the method, the roll shape curve of the working roll is a concave curve, the outlet plate shape convexity distribution is most directly controlled by directly adjusting the roll shape curve of the working roll, and the optimal concave roll curve of the working roll is optimized and solved by utilizing an optimization method, so that the best outlet plate shape convexity distribution is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of hot rolling, and in particular relates to a hot rolling plate shape optimization method considering a working roll profile curve. Background Art

[0002] Hot-rolled strip is a widely used industrial raw material, and the plate shape is the core quality indicator of hot-rolled strip. Its quality not only affects the competitiveness of hot-rolled strip itself, but also seriously affects the product quality and production smoothness of downstream users or processes that use hot-rolled strip as raw materials. With the development of modern industry, downstream users or processes have higher and higher requirements for the plate shape of hot-rolled strip. For this reason, the plate shape generation mechanism and its control method have always been a research hotspot in the field of plate and strip rolling and the focus of attention of plate and strip production enterprises. The plate shape quality of the rolling mill outlet can be controlled by changing the rolling pressure, front and rear tension, rolling temperature and roll shape of the stand, and the role of equipment in plate shape control is basic and long-term. For a specific wide strip hot rolling production line, the configuration and status of the equipment have a very important influence on the plate shape control, especially the rolling mill. Therefore, controlling the roll shape is one of the most direct, effective and flexible means to control the plate shape. The so-called control of the roll shape is to process the roll into a roller with a certain convexity to meet production requirements. The crown of a roller refers to a shape in which the middle of the roller surface is higher than the two ends, and looks like an arc with a slight bulge in the middle. The existence of crown can make the roller more resistant to bending and buckling during production, and can also improve the deformation process of the material and prevent the materials from sliding against each other, thus helping to improve the quality of the finished product.

[0003] Through this method of optimizing the roll shape, the ability to adjust the shape of rolled narrow strip steel can be significantly increased without increasing the roll diameter difference, so that one set of roll shapes can meet the needs of shape control of various specifications, reducing the number of roll shape configurations. In hot rolling production, the incoming materials have a high temperature, and the working rolls are in direct contact with the hot rolled incoming materials during the rolling process. During a long rolling process, the temperature of the working rolls themselves will be far higher than normal temperature. At this time, the working rolls will expand due to the heat, and the original roll shape will change, resulting in a decrease in the quality of the strip export shape. In order to adapt to the changes in the working roll shape caused by the temperature rise, the working rolls need to set the concave amount in advance to compensate for the convexity changes caused by thermal expansion. Therefore, it is very necessary to develop a shape optimization method for the four-roll mill with concave working rolls. Summary of the invention

[0004] In order to solve the problems raised in the background technology, the present invention provides a hot-rolled plate shape optimization method taking into account the working roll profile curve, wherein the working roll profile curve is set to a concave curve, and the convexity distribution of the outlet plate shape is most directly controlled by adjusting the working roll profile curve. The optimal working roll concave roll curve is searched and solved by an optimization method to obtain the best outlet plate shape convexity distribution.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A hot rolling strip shape optimization method considering a work roll profile curve comprises the following steps:

[0007] (a) Query key process and equipment parameters, mainly including: working roll diameter D w , working roll length L w , Support roller diameter D b , support roller length L b , rolling mill rolling pressure setting value P, front and rear outlet tension τ b , τ f , bending roll force S, roll shifting amount S p , safety factor η, rolling speed V, support roll and work roll neck length L wr , L br ;

[0008] (b) Given the product steel grade and specification characteristics; collect the hot rolling unit rolling strip steel type, incoming material thickness h0, initial deformation resistance σ s0 , the width of the strip B;

[0009] (c) assigning initial values ​​to the parameters in the calculation process, including calculating the optimization search step length Δ=0.01 and the allowable deviation range ε;

[0010] (d) Establishing the plate shape optimization objective function;

[0011] (e) Given the lowest point y of the initial concave roll curve of the working roll min ;

[0012] (f) Calculate the initial plate shape convexity distribution;

[0013] (g) Change the lowest point y of the working roll concave roll curve min The value of; the initial change result of the lowest point of the working roll concave roll curve is determined by the optimization search step, that is, y min =y min -Δ; the subsequent change amount needs to be determined in combination with the advance and retreat conditions of step (j), and the specific change amount is as introduced in step (j);

[0014] (h) fitting and calculating the working roll profile curve;

[0015] (i) Calculating and optimizing the convexity distribution of the plate shape; the calculation process is as in step (f);

[0016] (j) Judgment of conditions for advance and retreat method;

[0017] (j1) calculating an optimized initial plate shape objective function according to the initial outlet plate shape convexity distribution calculated in step (f);

[0018] (j2) calculating the optimized initial plate shape objective function according to the optimized outlet plate shape convexity distribution calculated in step (h);

[0019] (j3) The difference of the optimized flatness objective function before and after the judgment is as follows:

[0020] G(h) i+1 ≤ε,i≥0;

[0021] Where: ε is the allowable error limit; G(h) i is the plate shape objective function calculated by the optimization in step i; G(h) i+1 The plate shape objective function calculated by the optimization in the i+1th step;

[0022] If the judgment condition is met, continue to step (k); if the condition is not met, continue to the next condition judgment:

[0023] (j4) Determine the difference between the previous and next step lengths |Δ i -Δ i+1 |≤Δ; if the condition is met, proceed to step (k) to output the roller profile curve; if not, proceed to the next step of condition judgment;

[0024] (j5) The size of the optimized plate shape objective function before and after judgment:

[0025] G(h) i >G(h) i+1 ,i≥0;

[0026] If the judgment condition is satisfied, the process proceeds to step (g) to change the lowest point of the working roll concave roll curve, that is, to increase the lowest point of the current working roll concave roll curve by half of the previous step length; and the next step of searching is continued for the lowest point of the multi-roller concave roll curve; if the judgment condition is not satisfied, the process proceeds to step (g) to change the lowest point of the working roll concave roll curve, to reduce the lowest point of the current working roll concave roll curve by twice the previous step length, and refit the working roll profile curve; and the optimization is repeated in this way until the condition is satisfied;

[0027] (k) Output the final working roll profile curve.

[0028] Furthermore, the steps for establishing the plate shape optimization objective function in step (d) are as follows:

[0029] d1) First, the contact force-bearing part between the working roll and the strip is divided into n segments according to the segmented discrete method;

[0030] d2) Because the strip is divided into n segments, n+1 points will be generated; based on these points of the strip, the objective function is established as follows:

[0031]

[0032] Where: h i is the outlet plate convexity distribution, micrometer (μm); average outlet plate convexity: The unit is micrometer (μm).

[0033] Furthermore, the process of calculating the initial plate shape convexity distribution in step (f) is as follows:

[0034]

[0035] Where: is the deflection curve of the upper working roll; is the deflection curve of the lower working roll; is the roll profile curve of the upper working roll; is the roll profile curve of the lower working roll; K′ is the flattening coefficient between the working roll and the strip; q n ' +1 is the rolling pressure distribution value between the working roll and the strip at the n+1th point; q i ′ is the rolling pressure distribution at each segment point between the working roll and the strip.

[0036] Further, the method for fitting the working roll profile curve in step (h) is as follows: after obtaining the lowest point of the working roll concave roll curve according to step (g), it is known that the roll diameter at the two end points of the working roll is unchanged, and the two end points can be regarded as points with a vertical coordinate of zero, so that the three points are fitted into a one-variable quadratic function curve (l=ax 2 +bx+c), and regard this function curve as the concave roller profile curve.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention can predict the minimum rollable thickness of the hot rolling mill according to the strip steel specifications, strip steel starting rolling temperature, unit running speed, roll system equipment parameters, roll reduction distribution ratio, etc., and guide the optimization of the reduction distribution ratio through the random vector method to predict the minimum strip steel thickness, which can greatly reduce the calculation time and cost of the minimum rollable thickness. It can also expand the product outline and product specifications, and improve production efficiency and product quality by optimizing the reduction distribution ratio of each frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1It is a flow chart of a hot-rolled plate shape optimization method taking into account the roll profile curve of the working roll of the present invention. DETAILED DESCRIPTION

[0040] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Embodiment 1:

[0042] See also Figure 1 The present invention provides a hot rolling plate shape optimization method considering the roll profile curve of the working roll, comprising the following steps:

[0043] (a) Query key process and equipment parameters; mainly including: working roll diameter D w =400mm, working roll length L w =650mm, support roller diameter D b =650mm, support roller length L b =670mm, rolling mill rolling pressure setting value P i =6000KN, front outlet tension τ b =5MPa, rear outlet tension τ f =5MPa, bending roll force S=0, roll shifting amount S p =0, safety factor η = 0.9, rolling speed V = 8.6 m / s, support roll neck length L br =400mm, working roll neck length L wr =200mm, etc.

[0044] (b) Given the steel grade Q195 to be expanded, its specification parameters mainly include the incoming strip thickness h0 = 2.55 mm, the outlet thickness h1 = 1.91 mm, the initial deformation resistance σ s0 =328.7Mpa, strip width B = 310mm.

[0045] (c) Assigning initial values ​​to the parameters in the calculation process; mainly including calculating the optimization search step Δ=0.01 and the allowable deviation range ε=1.

[0046] (d) Establishing the plate shape optimization objective function; the establishment objective is as follows:

[0047] d1) Considering that the strip outlet width is 310 mm and for the convenience of calculation, the piecewise discrete method is used to divide the force-bearing part of the working roll in contact with the strip into n = 30 segments.

[0048] d2) Since the strip is divided into 30 sections, n+1=31 points will be generated. Based on these points of the strip, the objective function is established as follows:

[0049]

[0050] Where: h i is the outlet plate convexity distribution, micrometer (μm); average outlet plate convexity: The unit is micrometer (μm);

[0051] (e) Given the lowest point y of the initial concave roll curve of the working roll min ; Let the lowest point of the initial curve be y min = 0. Since the initial lowest point is zero, the roller profile curve l0 = 0.

[0052] (f) Calculate the initial plate shape crown distribution; According to the initial curve of the working roll, the 31 points obtained by the discrete segmentation method are calculated to calculate the initial plate shape crown distribution, and the calculation results are as follows:

[0053]

[0054] (g) Change the lowest point y of the working roll concave roll curve min value; According to the optimization search step and the initial lowest point, we know that: y min =y min -12Δ=-0.12mm.

[0055] (h) According to the lowest point y of the working roll concave roll curve min =-0.12mm, the working roll profile curve is fitted, and the curve fitting calculation results are as follows:

[0056] l=1.1361*10 -7 x 2 -0.0007385x+0

[0057] (i) According to the optimized work roll profile curve, the 31 points obtained by the discrete segmentation method are calculated, and the outlet plate profile convexity distribution is obtained as follows:

[0058]

[0059] (j) Judgment of conditions for advance and retreat method;

[0060] (j1) Calculated: Average convexity value of initial plate shape Initial shape objective function

[0061] Average convexity value of plate shape after optimization Optimized plate shape objective function

[0062] (j2) calculating the optimized initial plate shape objective function according to the optimized outlet plate shape convexity distribution calculated in step (h);

[0063] (j3) The difference of the optimized plate shape objective function before and after judgment:

[0064] G(h)1=0.56≤1,i≥0

[0065] After judgment, the difference between the plate shape objective function before and after optimization is within the allowable deviation range, the condition is met, and step (k) is continued.

[0066] (k) Output the final working roll profile curve l = 1.1361*10 -7 x 2 -0.0007385x+0;

[0067] Example 2:

[0068] (a) Query relevant key process and equipment parameters; the main query parameters include: working roll diameter D w =400mm, working roll body length L w =650mm, support roller diameter D b =650mm, support roller body length L b =670mm, rolling mill rolling pressure setting value P i =6000KN, front outlet tension τ b =5MPa, rear outlet tension τ f =5MPa, bending roll force S=0, roll shifting amount S p =0, safety factor η = 0.9, rolling speed V = 3.1 m / s, support roll neck length L br =400mm, working roll neck length L wr =200mm, etc.

[0069] (b) Given the steel grade and specification characteristics of the product; given the steel grade Q195 to be expanded, its specification parameters mainly include the incoming strip thickness h0 = 10.42 mm, the outlet thickness h0 = 6.67 mm, the initial deformation resistance σ s0 =211.7Mpa, strip width B=310mm.

[0070] (c) Assigning initial values ​​to the parameters in the calculation process; mainly including calculating the optimization search step Δ=0.01 and the allowable deviation range ε=1.

[0071] (d) Establishing the plate shape optimization objective function; the establishment objective is as follows:

[0072] d1) Considering that the strip outlet width is 310 mm and for the convenience of calculation, the piecewise discrete method is used to divide the force-bearing part of the working roll in contact with the strip into n = 30 segments.

[0073] d2) Since the strip is divided into 30 sections, n+1=31 points will be generated. Based on these points of the strip, the objective function is established as follows:

[0074]

[0075] Where: h i is the outlet plate convexity distribution, micrometer (μm); average outlet plate convexity: The unit is micrometer (μm);

[0076] (e) Given the lowest point y of the initial concave roll curve of the working roll min ; Let the lowest point of the initial curve be y min =-0.22 and the initial roll shape curve of the working roll is fitted according to the lowest point: l = 2.083*10 -7 x 2 -0.001354x+0.

[0077] (f) Calculate the initial plate shape crown distribution; According to the initial curve of the working roll, the 31 points obtained by the discrete segmentation method are calculated to calculate the initial plate shape crown distribution, and the calculation results are as follows:

[0078]

[0079] (g) Change the lowest point y min value; According to the optimization search step and the initial lowest point, we know that: y min =y min -0.5Δ=-0.225mm.

[0080] (h) According to the lowest point y of the working roll concave roll curve min =-0.225mm, the working roll profile curve is fitted, and the curve fitting calculation results are as follows:

[0081] l=2.1302*10 -7 x 2 -0.001385x+0

[0082] (i) According to the optimized work roll profile curve, the 31 points obtained by the discrete segmentation method are calculated, and the outlet plate profile convexity distribution is obtained as follows:

[0083]

[0084] (j) Judgment of conditions for advance and retreat method;

[0085] (j1) Calculated: Average convexity value of initial plate shape Initial shape objective function

[0086] Average convexity value of plate shape after optimization Optimized plate shape objective function

[0087] (j2) The difference of the optimized plate shape objective function before and after judgment:

[0088] G(h)1=1.35≥1,i≥0

[0089] After judgment, the difference between the plate shape objective function before and after optimization is greater than the allowable deviation range, and the condition is not met. Continue to the next step of judgment;

[0090] (j3) Calculate the difference between the previous and next step lengths:

[0091] |Δ0-Δ1|=0.005≤|Δ|=0.01

[0092] After judgment: the difference between the previous and next step lengths is less than the optimal search step length, the condition is met, and step (k) is continued.

[0093] (k) Output the final working roll profile curve l = 2.1302*10 -7 x 2 -0.001385x+0;

[0094] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A hot rolling strip shape optimization method considering the work roll profile curve, characterized in that: The steps include: (a) Query key process and equipment parameters, mainly including: working roll diameter D w , working roll length L w , Support roller diameter D b , support roller length L b , rolling mill rolling pressure setting value P, front and rear outlet tension τ b , τ f , bending roll force S, roll shifting amount S p , safety factor η, rolling speed V, support roll and work roll neck length L wr , L br ; (b) Given the product steel grade and specification characteristics; collect the hot rolling unit rolling strip steel type, incoming material thickness h0, initial deformation resistance σ s0 , the width of the strip B; (c) assigning initial values ​​to the parameters in the calculation process, including calculating the optimization search step length Δ=0.01 and the allowable deviation range ε; (d) Establishing the plate shape optimization objective function; (e) Given the lowest point y of the initial concave roll curve of the working roll min ; (f) Calculate the initial plate shape convexity distribution; (g) Change the lowest point y of the working roll concave roll curve min The value of; the initial change result of the lowest point of the working roll concave roll curve is determined by the optimization search step, that is, y min =y min -Δ; the subsequent change amount needs to be determined in combination with the advance and retreat conditions of step (j), and the specific change amount is as introduced in step (j); (h) fitting and calculating the working roll profile curve; (i) Calculating and optimizing the convexity distribution of the plate shape; the calculation process is as in step (f); (j) Judgment of conditions for advance and retreat method; (j1) calculating an optimized initial plate shape objective function according to the initial outlet plate shape convexity distribution calculated in step (f); (j2) calculating the optimized initial plate shape objective function according to the optimized outlet plate shape convexity distribution calculated in step (h); (j3) The difference of the optimized flatness objective function before and after the judgment is as follows: G(h) i+1 ≤ε,i≥0; Where: ε is the allowable error limit; G(h) i is the plate shape objective function calculated by the optimization in step i; G(h) i+1 The plate shape objective function calculated by the optimization in the i+1th step; If the judgment condition is met, continue to step (k); if the condition is not met, continue to the next condition judgment: (j4) Determine the difference between the previous and next step lengths |Δ i -Δ i+1 |≤Δ; if the condition is met, proceed to step (k) to output the roller profile curve; if not, proceed to the next step of condition judgment; (j5) The size of the optimized plate shape objective function before and after judgment: G(h) i >G(h) i+1 ,i≥0; If the judgment condition is satisfied, the process proceeds to step (g) to change the lowest point of the working roll concave roll curve, that is, to increase the lowest point of the current working roll concave roll curve by half of the previous step length; and the next step of searching is continued for the lowest point of the multi-roller concave roll curve; if the judgment condition is not satisfied, the process proceeds to step (g) to change the lowest point of the working roll concave roll curve, to reduce the lowest point of the current working roll concave roll curve by twice the previous step length, and refit the working roll profile curve; and the optimization is repeated in this way until the condition is satisfied; (k) Output the final working roll profile curve.

2. The hot rolling strip shape optimization method considering the work roll profile curve according to claim 1, characterized in that: The steps for establishing the plate shape optimization objective function in step (d) are as follows: d1) First, the contact force-bearing part between the working roll and the strip is divided into n segments according to the segmented discrete method; d2) Because the strip is divided into n segments, n+1 points will be generated; based on these points of the strip, the objective function is established as follows: Where: h i is the outlet plate convexity distribution, micrometer (μm); average outlet plate convexity: The unit is micrometer (μm).

3. The hot rolling strip shape optimization method considering the work roll profile curve according to claim 1, characterized in that: The process of calculating the initial plate shape convexity distribution in step (f) is as follows: Where: is the deflection curve of the upper working roll; is the deflection curve of the lower working roll; is the roll profile curve of the upper working roll; is the roll profile curve of the lower working roll; K′ is the flattening coefficient between the working roll and the strip; q n ' +1 is the rolling pressure distribution value between the working roll and the strip at the n+1th point; q i ′ is the rolling pressure distribution at each segment point between the working roll and the strip.

4. The hot rolling strip shape optimization method considering the work roll profile curve according to claim 1, characterized in that: The method for fitting the working roll profile curve in step (h) is as follows: after obtaining the lowest point of the working roll concave roll curve according to step (g), it is known that the roll diameter at the two end points of the working roll is unchanged, and the two end points can be regarded as points with a vertical coordinate of zero, so that the three points are fitted into a one-variable quadratic function curve (l=ax 2 +bx+c), and regard this function curve as the concave roller profile curve.

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