Casting roller shape design method for cooperative control of thermal crown compensation and edge reduction

Abstract

A casting roller shape design method for cooperative control of thermal convexity compensation and edge reduction is suitable for improving casting strip section defects caused by large thermal convexity of a casting roller in the thin strip casting and rolling process and comprises the steps that a casting roller body curve is divided into a middle area and an edge area according to the thermal expansion distribution condition of the casting roller, the middle area plays a key role in the overall section contour shape of the casting strip, and the edge area adjusts the rolling reduction to avoid the edge crack defect of the casting strip. A cosine curve of the middle area is designed based on the preset maximum-diameter roller shape height and the casting roller thermal convexity; then superposing two sections of cosine curves to obtain an edge curve; and further, in combination with continuous and smooth connection conditions of the curve, a roll shape curve of the whole roll body is finally obtained. According to the method, the roll shape of the casting roll is designed based on the piecewise function, the hot convexity compensation principle is followed, meanwhile, the edge pressing control of the casting strip is considered, the problem that the section shape of the casting strip is poor due to thermal expansion of the casting roll is effectively solved, and the probability of the edge crack defect of the casting strip is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metallurgical machinery, automation and rolling technology, and particularly relates to a cast roll shape design method for hot crown compensation and edge reduction coordination control. BACKGROUND

[0002] The steel industry is an important basic industry of the national economy. Promoting the greenization of the steel industry is one of the main development goals for the present and future. For this reason, many enterprises and research institutes at home and abroad actively carry out research and development and industrial application of endless rolling process and related technologies. Among them, double-roller thin strip casting and rolling is an advanced production process and cutting-edge manufacturing technology that integrates sub-rapid solidification and rolling deformation into one, with the advantages of short process, few procedures, low energy consumption and less emission. At the same time, due to the complexity of the process, there are still many problems to be solved in process control, equipment structure, product quality and process development.

[0003] The casting and rolling zone is the core process of thin strip casting and rolling, which is different from other continuous casting and rolling production lines. The casting roll is the core equipment of the thin strip continuous casting and rolling process, and it bears the functions of casting and rolling. Under the complex stress and high temperature environment, the structure and surface state of the casting roll have a very important influence on the plate shape and surface quality of the cast strip. The key to hot rolling plate shape control is the cross-sectional profile and flatness, and the cross-sectional profile quality of the cast strip directly affects the final plate profile quality of the subsequent rolling process. In addition, if the cast strip plate profile control is not good, it is easy to induce complex wave shape in the rolling process, which will endanger the stability of the rolling process.

[0004] When the casting roll is in contact with the high-temperature molten metal liquid, it will be subjected to a high temperature impact and will expand outward and generate thermal stress. Only by adopting a roll shape with a certain negative crown for the casting roll can the adverse effects of thermal expansion on the cast strip profile be effectively compensated. In addition, in actual production, the control of the edge reduction of the cast strip is also one of the key points to determine the quality of the cast strip. Excessive edge reduction will cause edge cracking defects of the cast strip, and the control of the edge of the cast strip is also a key point that must be considered in roll shape design.

[0005] In view of this, a roll shape design method based on a segmented function is proposed: the roll body of the casting roll is divided into a middle part and an edge part by using a segmented function, the middle part adopts a cosine function to offset the thermal expansion effect, and the edge part adopts two superimposed cosine functions to achieve fine adjustment of the edge reduction. By satisfying the continuity and smoothness conditions of the curve, an optimized roll shape curve covering the entire roll body is finally constructed, thereby realizing effective optimization control of the cross-sectional shape of the cast strip. SUMMARY

[0006] The application provides a method for designing a casting roll shape with heat crown compensation and edge reduction collaborative control, and solves the problem of cross section shape control of a cast strip caused by heat expansion of a roll body and edge reduction amount disorder under high temperature casting and rolling conditions.

[0007] To solve the above technical problems, the application provides the following technical solutions. A method for designing a casting roll shape with heat crown compensation and edge reduction collaborative control, characterized in that the casting roll shape is symmetrical about a center line of a roll body of the casting roll, and is divided into a middle part region and an edge part region of the casting roll in a length direction of the roll body of the casting roll, wherein the middle part region is a cosine function curve, and the edge part region is formed by superposition of two cosine functions, and finally a roll shape curve of the whole roll body is obtained in combination with a curve continuity and smooth connection condition.

[0008] Further, the length and height of the roll shape curve of the middle part region and the edge part region of the casting roll should satisfy:

[0009] wherein L is the total length of the roll body, in mm; H is a designed roll shape amount, including a crown setting, in μm; l mid Lm is the length of the middle curve, in mm; h mid Hm is the height of the middle curve, in μm; l side Le is the length of the single side edge curve, in mm; h side He is the height of the single side edge curve, in μm.

[0010] Further, the middle part region of the casting roll is a cosine function curve, including: The middle curve is determined according to geometric constraints, and y mid represents the cosine curve of the middle part, and the design emphasis is to compensate the heat crown, and the curve expression is:

[0011] wherein , , , is a constant of the cosine function y mid , wherein , T0 is a function period, and T 0 = l mid . Wherein the calculation methods of the parameters are as follows:

[0012] wherein is the hot crown compensation, unit: μm, and its value is the hot crown of the casting roll.

[0013] Further, the edge region of the casting roll is formed by superimposing two cosine functions, and the expression is:

[0014] wherein y side represents the edge curve, which is formed by superimposing two cosine curves y 1 and y 2 . Among them, y 1 The expression of

[0015] wherein , , , is the constant of the cosine function y 1 , wherein , T 1=2 l side . In order to make the whole roll curve smooth, y side and y mid The slope must be equal at the intersection point M, and the cosine function has multiple points with a slope of 0 in a half cycle, y side is l mid a complete period in the range, so y 1 The cosine function of 1 / 2 cycle is selected and the slope at P is 0, and the calculation method of each parameter is shown as follows:

[0016] The cosine curve y2 is mainly used to adjust the edge reduction amount, and the expression is:

[0017] According to the geometric constraint, the longitudinal height h side at the intersection point M and the end point N has been determined and is used as the solution condition of y 1, y 2after superimposing with y 1not only needs to meet the principle of smooth transition at the intersection point M, but also the coordinate value at the end point N should be equal to 0, otherwise the overall roll shape amount will change. Therefore y 2inl side a complete period should be taken within the range, and the amplitude for adjusting the edge reduction. y 2 parameters , , , The calculation method is as follows

[0018] In the formula is the edge reduction adjustment amount, unit: μm, set by the actual demand of the edge reduction.

[0019] The roll shape design of the whole roll body on the casting roll can be expressed by the comprehensive expression as follows:

[0020] Thus, the casting roll shape design is completed, and the segmented schematic diagram of the whole roll body roll shape is shown in Figure 1 .

[0021] The technical scheme provided by the present application has at least the following beneficial effects: The casting roll shape design method provided by the present application compensates the thermal expansion value of the casting roll by optimizing the roll shape parameters, thereby inhibiting the adverse effect of the thermal expansion value on the cross section profile of the casting strip. After the roll shape design is completed, the grinding can be performed in the form of discrete points on a grinding machine. Therefore, the present application has strong feasibility and low cost in the realization on the rolling mill. It has been proved that the casting roll shape provided by the present application can significantly improve the cross section shape control problem of the casting strip caused by the thermal expansion of the roll body and the edge reduction amount disorder under the high temperature casting and rolling condition. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiment description will be briefly introduced as follows.

[0023] Figure 1 is the geometric segmented schematic diagram of the whole roll body roll shape of the present application; Figure 2 is the temperature distribution of the casting roll of the present application. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical scheme and advantages of the present application more clear, the embodiments of the present application will be further described in detail with reference to the drawings.

[0025] First embodiment

[0026] The embodiment provides a method for designing a casting roll shape by combining thermal crown compensation and edge press-down control, and solves the problem of controlling the cross-section shape of a cast strip caused by thermal expansion of a roll body and disordered edge press-down under high-temperature casting and rolling conditions. The effect of the application is further illustrated by an actual application example.

[0027] A double-roll thin strip casting and rolling production line of a certain plant mainly rolls a product with a width of 1340 mm, and the length of a roll body of a casting roll is 1340 mm. When the casting roll contacts with high-temperature molten metal, the casting roll bears a high temperature impact, expands outward and generates thermal stress, which has an adverse effect on the cross-section profile of the cast strip.

[0028] According to the content of the embodiment, a corresponding casting roll shape curve is designed. According to the requirement of a production site on the cross-section profile of the cast strip, the maximum radius of the casting roll is 300 μm, and the crown index of the cast strip is 50 μm. The length and height of the roll shape curve of the middle region and the edge region of the casting roll should satisfy the following conditions:

[0029] In the formula, L is 1340 mm; H is 350 μm; l mid is 1240 mm; h mid is 260 μm; l side is 50 mm; h side is 40 μm.

[0030] Further, the middle region of the casting roll is a cosine function curve, which includes: The middle cosine curve is determined according to geometric constraints, and y mid represents the middle cosine curve, and the design emphasis is to compensate the thermal crown. The curve expression is:

[0031] In the formula, a, b, c and d are constants of the cosine function , , , , y mid , wherein , T0 is a function period, and T 0 l mid The calculation methods of the parameters are as follows:

[0032] It is calculated that =-155; ​= 0.01, = 0, = 155.

[0033] wherein is the thermal crown compensation, unit: μm, and its value is the thermal crown of the casting roll, which is 50 μm.

[0034] Further, the edge region of the casting roll is formed by superimposing two cosine functions, and the expression is:

[0035] wherein y side represents the edge curve, which is formed by superimposing two cosine curves y 1 and y 2 . Among them, y 1 the expression of

[0036] wherein , , , is the constant of the cosine function y 1 , wherein T 1=2 l side = 100 mm, . In order to make the whole roll curve smooth, y side and y mid The slope must be equal at the intersection point M, and the cosine function has multiple points with a slope of 0 in a half cycle, y side is l mid a complete cycle in the range of y 1 Therefore, the cosine function of 1 / 2 cycle is selected, and the slope at P is 0, and the calculation method of each parameter is as follows:

[0037] It is calculated that: = 20; = 0.06, = 100, = 330.

[0038] The cosine curve y2 is mainly used to adjust the edge reduction amount, and the expression is:

[0039] From the geometric constraints, the longitudinal height of the intersection point M and the end point N h side It has been determined, and as y 1 solving condition, y 2 after superimposed with y 1 Not only need to meet the principle of smooth transition at the intersection point M, and the coordinate value at the end point N should be equal to 0, otherwise the overall roll shape will change. Therefore y 2 in l side A complete cycle should be taken within the range For the edge pressure adjustment. The edge pressure adjustment is-5 microns. y 2 parameters , , , The calculation method is as follows

[0040] The calculation is as follows: =-2.5, =0.13, =-81.05, =-2.5.

[0041] So far, the roll shape design of the whole roll body on the casting roll has been completed, and the comprehensive expression can be expressed as:

[0042] The discrete point data of the roll shape curve is submitted to the grinding machine, and after grinding, it is applied to the production site, and the cross section of the casting strip is obviously improved. It can be seen that the roll shape provided by the present application has remarkable effect on the improvement of the cross section profile of the casting strip.

[0043] In summary, the casting roll shape design method provided by the embodiment optimizes the roll shape parameters to compensate for the thermal expansion value of the casting roll, thereby suppressing its adverse effects on the cross section profile of the casting strip. After the roll shape design is completed, the grinding can be performed in the form of discrete points on the grinding machine. After the on-machine experiment on the production line of a certain factory, it is shown that the casting roll shape provided by the embodiment for the cooperative control of thermal crown compensation and edge pressure can significantly improve the cross section shape control problem of the casting strip caused by the thermal expansion of the roll body and the disordered edge pressure under high temperature casting and rolling conditions.

Claims

1. A method for designing the shape of a casting roll with coordinated control of thermal crown compensation and edge pressing, characterized in that, The roll shape is symmetrical about the center line of the roll body. It is divided into a central region and an edge region along the length of the roll body. The central region is a cosine function curve, and the edge region is formed by the superposition of two cosine functions. Combining the conditions of continuous and smooth curve connection, the roll shape curve of the entire roll body is finally obtained.

2. The casting roll shape with coordinated control of thermal crown compensation and edge pressing as described in claim 1, characterized in that, The length and height of the roll profile curves in the central and edge regions of the casting roll should meet the following requirements: Where L is the total length of the roller body, in mm; H is the designed roller profile, including the crown setting, in μm; l mid The length of the central curve, in mm; h mid The height of the central curve, in μm; l side The length of a single-sided curve, in mm; h side The height of a single-sided curve, in μm.

3. The roller shape design method as described in claim 1, characterized in that, The central region of the casting roll is a cosine function curve, including: The middle curve is determined based on geometric constraints, with y mid The cosine curve representing the middle section is designed to compensate for thermal convexity. Its curve expression is: In the formula , , , cosine function y mid The constant, where T0 is the period of the function, and T 0 = l mid The calculation methods for each parameter are as follows: In the formula This is the thermal crowning compensation amount, in μm, and its value is the thermal crowning of the casting roll.

4. The roller shape design method as described in claim 1, characterized in that, The edge region of the casting roll is formed by the superposition of two cosine functions, expressed as: y side The edge curve is represented by two cosine curves. y 1 and y 2 It is formed by superposition; among them, y 1 The expression is: In the formula , , , cosine function y 1 The constant, where , T 1=2 l side To ensure a smooth curve across the entire roller body, y side and y mid At the intersection point M, the slopes must be equal, but the sine and cosine functions will have multiple points with a slope of 0 within half a period. y side yes l mid A complete cycle within the range, therefore y 1 Using a cosine function with a period of 1 / 2 and a slope of 0 at point P, the calculation methods for each parameter are as follows: The cosine curve y2 is mainly used to adjust the edge compression amount, and its expression is: According to geometric constraints, the longitudinal height at intersection point M and endpoint N is... h side It has been determined and is as y The solution conditions for 1, y 2 in relation to y After superposition, not only must the principle of smooth transition at the intersection point M be met, but the coordinate value at the endpoint N should also be equal to 0; otherwise, the overall roll shape will change. Therefore... y 2 in l side A complete cycle should be taken within the range, and the amplitude should be... Used to adjust the amount of edge compression; y 2 parameters , , , The calculation method is as follows: In the formula This is the edge pressing adjustment amount, in μm, which is set according to the actual edge pressing requirements; This completes the roll shape design for the entire roll body on the upper surface of the casting roll. The comprehensive expression can be represented as: 。

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