Method for controlling head edge wave of wide thin steel sheet
By pre-setting the bending roll force Fb in the finishing rolling stage to pre-form a negative convexity roll gap in the transverse direction, the problem of edge waviness at the head of wide thin steel plates was solved, and the production of steel plates with high flatness was achieved, thereby improving production efficiency and product competitiveness.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WUHAN IRON & STEEL GRP ECHENG IRON & STEEL CO LTD
- Filing Date
- 2023-07-28
- Publication Date
- 2026-07-03
AI Technical Summary
In the finishing rolling process of wide thin steel plates, especially at the head, edge waviness often occurs, making it difficult to meet the high standards of end users in terms of flatness. Existing methods are not effective in controlling this at the head.
Before the last loaded pass in the finishing rolling stage, the preset value Fb of the bending roll force is obtained by calculation, so that the transverse loaded roll gap of the roll forms a negative convexity, which counteracts the impact force when the steel plate head bites in and controls the edge waviness of the steel plate head.
It significantly reduces the flatness error of the steel plate head to below 1.2mm/1000mm, meeting the high flatness requirements of end users, shortening the production process and reducing costs.
Smart Images
Figure CN117123625B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of steel plate processing quality control technology, and in particular to a method for controlling the edge waviness problem at the head of wide, thin steel plates. Background Technology
[0002] Wide and thick steel plates have a wide range of applications, mainly used in the production and construction of buildings or special equipment such as roads and bridges, ships, high-rise buildings, oil pipelines and oil storage tanks. Thin-gauge wide and thick plates (thickness ≤ 16mm, width ≥ 3000mm) are even more important strategic materials, used in the construction of large ships, giant bridge structural steel, large dam gates, and other important large-scale equipment. Wide and thick plates can reduce the number of weld seams, shortening the shipbuilding and bridge construction cycle. At the same time, reducing the number of weld seams increases the overall strength of the structural components. However, this places high demands on the straightness of the thin-gauge wide steel plate in the weld seams.
[0003] In recent years, more and more end users of wide and heavy plates have put forward stringent standards for the flatness of thin and wide steel plates (straightness of steel plate: 3mm / 1000mm). This requirement is far higher than the standard specified in the national standard GB / T709-2019 for hot-rolled steel plates, which stipulates that the flatness of steel L is 7mm / 1000mm and the flatness of steel H is 10mm / 1000mm.
[0004] In the actual production of thin-gauge wide steel plates, due to the thinness and width of the plates, the final rolling temperature is generally between 820-880℃. During the rolling process, the deformation resistance of the steel plate increases significantly, making it difficult to control the plate shape. Wavy edges are a common shape defect. This is especially pronounced at the head of the plate, where the temperature is relatively lower, often resulting in excessive flatness and failure to meet user requirements.
[0005] Currently, the traditional method for controlling the edge waviness of steel plates in heavy plate rolling mills is to optimize the roll profile curve and, in conjunction with the mill's bending and shifting roll functions, achieve changes in roll crown to improve the unevenness of the roll gap under transverse load, thereby controlling the edge waviness of the steel plate. For example, Chinese patent application CN103203370A discloses a method for controlling edge waviness in high-strength steel. This method uses two SFR rolls with wavy curved surfaces. When controlling the edge waviness problem, the two SFR rolls move relative to each other along their axial direction. The parameters of this movement are manually adjusted to change the roll gap from zero crown to negative or positive crown, allowing the roll gap to be adjusted accordingly based on the edge waviness problem, thus improving the mill's control over the steel plate shape.
[0006] However, these traditional methods have high requirements for steel plate processing equipment and can only improve the waviness of most areas of the steel plate. When rolling the head of the steel plate, the unevenness of the transverse loaded roll gap caused by the bite impact and increased rolling force results in poor head edge waviness control. Summary of the Invention
[0007] To address the frequent occurrence of edge waviness / wavy appearance at the head of wide thin steel plates (generally ≥3000mm wide) during the finishing rolling process, this invention provides a method for controlling edge waviness in wide thin steel plates. This method can significantly reduce the flatness of the steel plate head, and is specifically achieved through the following techniques.
[0008] A method for controlling the head edge waviness problem of wide thin steel plates includes the following steps:
[0009] Obtain the preset value Fb of the bending roller force 预 Determine Fb 预 Rolling length L acting on the head of the steel plate 头 ;
[0010] Before the head of the steel plate in the last loaded pass of the finishing rolling stage bites into the mill, according to Fb 预 Set the bending force to make the transverse loaded roll gap of the roll form a negative convexity;
[0011] When the head of the last steel plate in the finishing rolling stage is bitten in, finishing rolling begins until the rolling length reaches L. 头 At this point, the bending roll force is restored to its initial value, and subsequent steel plate rolling continues.
[0012] Steel plate rolling consists of two steps: roughing and finishing. The steel is first rough-rolled on a roughing mill, with the number of passes depending on specific requirements, typically more than ten. After roughing, finishing is performed, also involving multiple passes depending on specific requirements. The method for controlling the edge waviness of wide, thin steel plates provided in this application is an improvement on the final loaded pass of the finishing stage. The developers of this patent technology believe that the essence of edge waviness in thin, wide steel plates is that during the finishing rolling process, the lateral deformation of the finishing rolls creates a certain amount of deflection, leading to uneven lateral loaded roll gaps. Microscopically, during finishing rolling, the metal flow at the edge of the steel plate is faster than in the middle, resulting in a macroscopic waviness.
[0013] Therefore, in the control method provided by the present invention, Fb 预 This refers to the rolling force (i.e., the bending force in step S2) that the rolls of the last loaded pass need to apply to the steel plate when the finishing mill begins finishing. For highly automated mills, the entire calculation yields Fb. 预 And Fb 预 The entire process of applying the coating to the rolls requires no operator intervention; operators typically only need to input the corresponding raw parameters on the mill's operating interface. 头 Is it maintaining the application of Fb 预Under these conditions, the steel plate head travels the distance while being rolled on the last loaded pass of the finishing mill. This is achieved through the intake of Fb... 预 The value of S determines the negative crown of the transverse loaded roll gap during finish rolling, i.e., the roll gap value S on both sides of the roll. 边 Greater than the roll gap value S in the middle of the rolling mill 中 When the head of a thin, wide steel plate is bitten in, the biting impact force generated by the rolls causes the temperature of the steel plate head to be low and the rolling force to be high. This causes the transverse roll gap to change from negative convexity to horizontal, thereby achieving the purpose of controlling the waviness of the edge of the steel plate head.
[0014] Preferably, Fb 预 The calculation method is as follows: before the head of the steel plate bites into the mill in the last loaded pass of the finishing rolling stage, the head rolling force F is calculated by the mill's built-in data model. 头 and the middle rolling force F 中 According to the formula
[0015] Fb 预 =[(F 头 -F 中 )×Fb 设 ] / G
[0016] Calculate and obtain Fb 预 Where G is the elastic modulus of the roll, and Fb 设 This refers to the roll bending force of the last loaded pass in the finishing rolling stage.
[0017] In the above formula, Fb 设 This refers to the roll bending force value of the last loaded pass in the finishing rolling stage. This value can be calculated using the mill's built-in process calculation program (i.e., the mill's built-in data model) and is known. F 头 and F 中 These refer to the rolling forces experienced by the head and middle sections of the steel plate before it enters the final loaded pass in the finishing rolling stage. These rolling forces are also calculated using the mill's built-in process calculation program. Currently, the steel plate rolling mills used in the industry have a high degree of automation and intelligence. 设 F 头 and F 中 These are all theoretical values that can be calculated using built-in software programs. There are already many mature commercial software products available for built-in software programs used in steel plate rolling mills. Operators only need to input the original parameters of the steel plate (such as thickness) into the mill's built-in software program, and the Fb value can be directly obtained through a series of calculations performed by the built-in software program and intelligent algorithms. 设 F 头 and F 中G is the elastic modulus coefficient of the roll, which is a constant and is related to the properties of the roll itself. For example, G for high-chromium iron rolls is 21.5-22.5.
[0018] The calculation process of the above formula can also be considered to be completed through the automatic system built into the rolling mill. Once G and Fb are set... 设 Calculated according to the calculation program in the rolling mill, and F 头 F 中 It can be automatically monitored and imported into the automated system, allowing Fb to be directly output on the rolling mill. 预 And according to Fb 预 Set the bending force of the rolls.
[0019] During finish rolling, the bending roll force is pre-set to Fb. 预 By creating a negative convexity in the transverse loaded roll gap in advance, the influence of the increased rolling force due to the bite of the steel plate head on the transverse loaded roll gap can be offset. At this time, the transverse loaded roll gap changes from negative convexity to horizontal, thereby achieving the purpose of controlling the waviness of the steel plate head edge.
[0020] Preferably, the rolling length L at the head of the steel plate 头 The method for determining the L is as follows: Select several steel plates of different thicknesses that have undergone rough rolling, and use the straightness of the steel plate head reaching 3mm / 1000mm as the standard to obtain the corresponding L. 头 With the steel plate thickness D as the abscissa, L 头 Plot a standard curve with the vertical axis as the ordinate; determine L based on the equation of the standard curve and the thickness of the steel plate to be finished rolled. 头 .
[0021] More preferably, when the steel plate width is ≥3000mm and the thickness is 12-16mm, the rolling length L at the head of the steel plate is... 头 The standard curve for the thickness D of the steel plate is L. 头 = -0.2943D + 5.667, R 2 =0.9033.
[0022] More preferably, when the steel plate width is ≥3000mm and the thickness is 6-12mm, L 头 The standard curve for D is L 头 = -0.314D + 6.128, R 2 =0.9616.
[0023] Through a large number of steel plate thicknesses D and corresponding L 头 By fitting the model, the corresponding standard curve equation can be obtained. Based on this model equation, the length of the head of a wide thin steel plate of any thickness that needs to be rolled can be obtained.
[0024] To further improve the control method of this invention, specifically to further enhance the flatness of the steel plate head, the thickness is divided into two stages: 12-16mm and 6-12mm. For these two thickness ranges, different standard curve equations are selected to obtain L. 头 .
[0025] Compared with the prior art, the advantages of the present invention are as follows: The method for controlling the head edge waviness problem of wide-width thin steel plates provided by the present invention solves the long-standing problem of head waviness defects in the production of thin-gauge wide steel plates. It can be applied to various steel grades, and the flatness of the steel plate head can be as low as 1.2mm / 1000mm. It provides strong technical support for shortening the steel plate production process and reducing production costs, and provides a strong guarantee for meeting the high flatness requirements of end users of wide and thick plates and enhancing the market competitiveness of products. Attached Figure Description
[0026] Figure 1 This is a schematic diagram illustrating the principle of controlling the shape change of the transverse loaded roll gap using traditional methods.
[0027] Figure 2 This is a schematic diagram illustrating the principle of the change in the shape of the transversely loaded roll gap after adopting the new production method.
[0028] Figure 3 When the width of the steel plate is ≥3000mm and the thickness is 12-16mm, the rolling length L of the steel plate head is... 头 The standard curve of the steel plate thickness D;
[0029] Figure 4 When the width of the steel plate is ≥3000mm and the thickness is 6-12mm, the rolling length L of the steel plate head is... 头 The standard curve for the thickness D of the steel plate. Detailed Implementation
[0030] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0031] The control methods for the head edge waviness problem of wide thin steel plates provided in the following embodiments all adopt the following methods, and the specific steps are as follows:
[0032] (1) Before the last loaded pass of the finishing mill during the finishing rolling of the steel plate, the built-in process calculation program of the finishing mill calculates the rolling force F that needs to be applied to the head of the steel plate. 头 and the middle rolling force F 中 According to the formula
[0033] Fb 预 =[(F 头 -F 中 )×Fb 设 ] / G
[0034] Calculate the preset value Fb of the bending roller force 预 Wherein, G is the elastic modulus of the roll; the rolls used in the following embodiments are high-chromium iron rolls, G = 21.5-22.5, Fb 设 The bending force of the rolls in the last loaded pass of the finishing rolling stage;
[0035] Fb 设 F 头 and F 中 The data was obtained through the built-in data model of the rolling mill (4300mm wide and thick plate rolling mill of Baowu Group Echeng Iron & Steel Co., Ltd.) (the software program was provided by Pratt & Co.).
[0036] (2) Determine Fb 预 Rolling length L acting on the head of the steel plate 头 ;
[0037] (3) Before the last steel plate in the finishing rolling stage is bitten in, according to Fb 预 Setting a bending force causes the transverse loaded roll gap of the roll to form a negative convexity, thereby offsetting the effect of the increased rolling force due to the bite impact of the steel plate head on the transverse loaded roll gap; at this time, the transverse loaded roll gap of the roll changes from negative convexity to horizontal, thereby achieving the purpose of controlling the waviness of the edge of the steel plate head.
[0038] like Figure 1 , 2 As shown, Figure 1 As can be seen in the text, when using the traditional finishing rolling method, (b) after the steel plate is bitten in, the shape of the transverse roll gap is uneven, exhibiting a "positive convexity", which leads to the problem of edge waviness at the head of the steel plate; Figure 2 As can be seen, by pre-setting the bending roller force Fb before the steel plate bites in... 预 This causes the transverse load gap of the rolls to have a "negative convexity," so that the transverse load gap of the rolls changes to "horizontal" after the steel plate bites in.
[0039] (4) When the head of the steel plate bites in and rolling begins, when the mill foundation automation system recognizes that the rolling length of the steel plate head has reached L 头 At that time, an instruction is issued to cancel the preset bending roller force Fb. 预 Then restore the bending roll force to its initial value and continue the subsequent steel plate rolling.
[0040] Example 1: Rolling length L 头 Determination of the standard curve model for steel plate thickness D
[0041] This embodiment employs the above-described method, selecting several steel plates of different thicknesses that have undergone rough rolling. Besides Q355B or Q420R, various steel grades such as Q345R, Q370R, Q345q, and Q420q are also applicable. The flatness of the steel plate head is tested using the method disclosed in GB / T709-2019. A flatness of 3mm / 1000mm at the steel plate head is used as the standard to obtain the corresponding L... 头 The experimental data are shown in Table 1 below.
[0042] Table 1. Steel plates of different grades and thicknesses and L 头 Data Results
[0043]
[0044] With the steel plate thickness D as the x-axis, L 头 Plot a standard curve with the vertical axis as the ordinate;
[0045] like Figure 3 As shown, when the steel plate width is ≥3000mm and the thickness is 12-16mm, the rolling length L at the head of the steel plate is... 头 The standard curve for the thickness D of the steel plate is L. 头 = -0.2943D + 5.667, R 2 =0.9033.
[0046] like Figure 4 As shown, when the steel plate width is ≥3000mm and the thickness is 6-12mm, L 头 The standard curve for D is L 头 = -0.314D + 6.128, R 2 =0.9616.
[0047] Example 2: Method verification for different types of steel plates
[0048] Using the above method and the standard curve model of Example 1, steel grades Q355B (steel type L) and Q420R (steel type H) were selected. The test results are shown in Tables 2 and 3 below. Table 2 shows the test results for steel grade Q355B (steel type L). Table 3 shows the test results for steel grade Q420R (steel type H).
[0049] Table 2 Test Results of Steel Grade Q355B (Steel Category L)
[0050]
[0051] Table 3 Test Results of Steel Grade Q420R (Steel Type H)
[0052]
[0053] As can be seen from the above embodiments 1 and 2, using the method provided by the present invention, and the rolling length L 头 The standard curve model of the steel plate thickness D can effectively control the head edge wave problem of wide thin steel plates.
[0054] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
Claims
1. A method of controlling head edge waviness of a wide thin steel sheet, characterized by, comprising the steps of: obtaining a preset value Fb of bending force 预 , determining Fb 预 rolling length L acting on the head of the steel plate 头 ; At the end of the finishing stage, before the head of the last pass of the steel sheet bites into the mill, the Fb 预 The bending force is set to form a negative crown in the transverse loaded roll gap of the roll. When the head of the last pass of the steel sheet in the finishing stage is bitten to start the finishing rolling until the rolling length reaches L 头 , the bending force is restored to the initial value, and the subsequent steel sheet rolling is continued.
2. The method for controlling the head edge waviness problem of wide-width thin steel plates according to claim 1, characterized in that, Fb 预 The calculation method is as follows: before the head of the steel plate bites into the mill in the last loaded pass of the finishing rolling stage, the head rolling force F is calculated by the mill's built-in data model. 头 and the middle rolling force F 中 According to the formula Fb 预 = [(F 头 - F 中 ) x Fb 设 ] / G Calculate and obtain Fb 预 Where G is the elastic modulus of the roll, and Fb 设 This refers to the roll bending force of the last loaded pass in the finishing rolling stage.
3. The method of controlling head edge wave of a wide thin steel sheet according to claim 1, characterized by, Rolling length L of the steel plate head 头 The method for determining the L is as follows: Select several steel plates of different thicknesses that have undergone rough rolling, and use the straightness of the steel plate head reaching 3mm / 1000mm as the standard to obtain the corresponding L. 头 With the steel plate thickness D as the abscissa, L 头 Plot a standard curve with the vertical axis as the ordinate; determine L based on the equation of the standard curve and the thickness of the steel plate to be finished rolled. 头 .
4. The method of controlling head edge wave of a wide thin steel sheet according to claim 3, characterized by When the width of the steel plate is ≥3000mm and the thickness is 12-16mm, the rolling length L of the steel plate head is... 头 The standard curve for the thickness D of the steel plate is L. 头 = -0.2943D + 5.667, R 2 =0.9033.
5. The method of controlling head edge wave of a wide thin steel sheet according to claim 3, characterized by, When the steel plate width is ≥ 3000 mm and the thickness is 6-12 mm, L 头 and the standard curve of D is L 头 = -0.314D + 6.128, R 2 = 0.9616.
6. The method of controlling head edge wave of a wide thin steel sheet according to claim 2, characterized by Fb 设 Obtained by calculation of the built-in data model of the rolling mill.