A design method of a gradual curvature profile roller

Abstract

The application provides a design method of a gradually changing curvature convex roll, and the specific steps comprise determining the convection heat transfer coefficients of different secondary cooling zones according to water flow density, further determining the final solidification position of a casting blank, selecting the convex platform length corresponding to the maximum deformation of the final solidification position under the target reduction, designing multiple groups of convex platform height and gradual change length, calculating the peak stress and the blank resistance of the casting blank surface corresponding to each group of convex platform height and gradual change length, selecting the convex platform height and gradual change length corresponding to the minimum peak stress of the casting blank surface when the blank resistance does not exceed the limit output pressure of the continuous casting machine, and finally processing the gradually changing curvature convex roll according to the convex platform length, the convex platform height and the gradual change length. The design method of the gradually changing curvature convex roll can effectively increase the reduction of the continuous casting machine, improve the center line segregation condition, and is applicable to the working conditions of the non-uniform solidification liquid core width being less than the convex platform length, and has strong applicability.

Description

Technical Field

[0001] This invention relates to the field of continuous casting equipment design technology, and in particular to a design method for a gradually curvature curved roller. Background Technology

[0002] With the rapid development of my country's industry, the demand for large-section steel is constantly increasing. Under the premise of ensuring a certain rolling compression ratio, the cross-section of the billet increases with the increase of the steel cross-section. During continuous casting, due to the long two-phase zone, large solidification shrinkage, and severe solute enrichment in the molten steel of the large-section billet, central segregation and central porosity are aggravated, resulting in banded segregation and uneven Z-axis properties of the rolled product, which seriously restricts the performance of the rolled product.

[0003] The existing main solution is to apply light reduction in the two-phase region of the billet, promoting the flow of solute-enriched molten steel by applying a certain reduction amount, thereby improving the segregation and porosity in the center of the billet. However, as the billet widens and thickens, the reduction amount of light reduction is difficult to penetrate to the core of the billet, resulting in limited improvement on the internal quality of the billet. Therefore, based on light reduction, heavy reduction technology has been further developed, which applies a larger reduction amount at the end of solidification to improve the internal quality of the billet. However, increasing the reduction amount inevitably leads to an increase in the pressing force, especially as the hardness of the billet increases after complete solidification, exacerbating the increase in pressing resistance. Existing continuous casting machines have limited reduction capacity, significantly increasing the cost of applying this technology. Therefore, the common approach is to change the roll profile to increase the reduction amount while not exceeding the reduction limit of the equipment, in order to improve the internal quality of the billet.

[0004] However, the existing design methods for curved rollers do not take into account the unique cross-sectional non-uniform solidification characteristics of thick slabs, or they do not consider the gradual transition between raised and non-raised parts, resulting in limited applicability and relatively complex actual operation.

[0005] Therefore, a design method for a gradient curvature roller that is versatile and easy to operate is urgently needed. Summary of the Invention

[0006] To address the shortcomings of the existing technologies, this invention provides a design method for a gradually curvature curved roller, which solves the technical problems of limited applicability and complex actual operation of the existing curved roller design methods.

[0007] This invention provides a design method for a gradient curvature curved roller, wherein the convex roller includes a roller body, a boss, and a gradient zone. The design parameters of the convex roller include boss length, boss height, and gradient length. The method includes:

[0008] The water flow density in the secondary cooling zone is obtained, and the convective heat transfer coefficient is calculated based on the water flow density. The final solidification position of the billet is determined based on the water flow density and the convective heat transfer coefficient.

[0009] Obtain the deformation and billet resistance at the final solidification position corresponding to different boss lengths under the same reduction amount. When the billet resistance is less than or equal to a preset parameter, select the boss length corresponding to the maximum deformation at the final solidification position. The preset parameter is the limit output pressure of the continuous casting machine.

[0010] Based on the target reduction amount, multiple sets of boss heights and gradient lengths are obtained. The peak stress and pressing resistance of the billet surface corresponding to each set of boss heights and gradient lengths are calculated. When the pressing resistance is less than or equal to a preset parameter, the boss height and gradient length corresponding to the minimum peak stress on the billet surface are selected.

[0011] The gradient curvature convex roller is processed according to the boss length, the boss height, and the gradient length.

[0012] Optionally, obtaining the water flow density in the secondary cooling zone includes:

[0013] Connect the water inlet of the continuous casting machine nozzle to the water source and air pump, so that the height distance between the top of the continuous casting machine nozzle and the water pipe is equal to the vertical distance from the continuous casting machine nozzle to the surface of the billet, thereby allowing the water sprayed from the continuous casting machine nozzle to flow into the water pipe.

[0014] The water volume distribution of the continuous casting machine nozzle is determined based on the water height in the water pipe.

[0015] The water flow distribution of all the continuous casting machine nozzles in the width direction of the billet is superimposed to obtain the water flow density of the secondary cooling zone in the width direction.

[0016] Optionally, the step of calculating the convective heat transfer coefficient based on the water flow density includes:

[0017] The convective heat transfer coefficient is calculated using the following formula:

[0018] h i spary＝ a i W i 0.55 (1-0.075T w )

[0019] Among them, h i spary Let i be the convective heat transfer coefficient, i be the secondary cooling zone, and a be the convective heat transfer coefficient. i For continuous casting machine parameters, W iT is the water flow density. w This refers to the water temperature in the secondary cooling zone.

[0020] Optionally, obtaining the deformation and compact resistance at the final solidification position corresponding to different boss lengths under the same reduction includes:

[0021] Based on the three-dimensional thermo-mechanical coupling model of convex roll pressing, the thermodynamic behavior of the convex roll pressing process with different design parameters is calculated;

[0022] Based on the aforementioned thermodynamic behavior, the deformation and compact resistance at the final solidification position corresponding to different boss lengths under the same reduction amount are calculated.

[0023] Optionally, before processing the gradient curvature convex roller according to the boss length, the boss height, and the gradient length, the method further includes:

[0024] The parametric equation for the third-order Bethesda curve of the gradient region, determined based on the boss height and the gradient length, is as follows:

[0025] x(t)=L GC t 3 -3 / 2L GC t 2 +3 / 2L GC t(0≤t≤1)

[0026] y(t)=-2H PC t 3 +3H PC t 2 (0≤t≤1)

[0027] Among them, L GC H is the gradient length. PC The height of the boss is [value].

[0028] Optionally, the step of processing the gradient curvature convex roller according to the boss length, the boss height, and the gradient length includes:

[0029] Keeping the diameter of the boss's length portion constant, the two sides of the roller body are cut according to the parametric equation of the third-order Bethesda curve of the gradient zone, wherein the diameter of the boss is D. roll The diameter of the roller body is D. roll -2H PC .

[0030] Optionally, after obtaining the water flow density in the secondary cooling zone, calculating the convective heat transfer coefficient based on the water flow density, and determining the final solidification position of the billet based on the water flow density and the convective heat transfer coefficient, the method further includes:

[0031] Based on the final solidification position, the pressed sector segment where the final solidification position is located is obtained, and the pressed sector segment is set as the modified sector segment of the convex roller.

[0032] Optionally, the pressed-down sector covers the region with a solidity of 0.85-1 at the final solidification location.

[0033] Optionally, after processing the gradient curvature convex roller according to the boss length, the boss height, and the gradient length, the method further includes:

[0034] The gradually curvature convex roller is assembled onto the modified sector section of the convex roller.

[0035] The design method of the gradually curvature convex roll provided by this invention obtains the morphology of the solidification front of the billet to determine the final solidification position, and calculates data such as the peak stress and pressing resistance of the billet surface. At the same time, the design parameters of the gradually curvature convex roll are determined based on three criteria: maximizing the core deformation of the billet, minimizing the peak value of the billet surface, and not exceeding the limit output pressure of the continuous casting machine. This method can effectively increase the reduction of the continuous casting machine, improve the centerline segregation, and is applicable to convex rolls in cases where the width of the non-uniform solidified liquid core is less than the length of the boss, thus having strong applicability.

[0036] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings.

[0037] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0038] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0039] Figure 1 A flowchart illustrating a design method for a gradually curvature convex roller provided in an embodiment of this application;

[0040] Figure 2 This is a schematic diagram of the structure of the convex roller in the design method of the gradually curvature convex roller provided in the embodiments of this application;

[0041] Figure 3 This is the morphology of the solidification front of the billet in a design method for a gradually curvature convex roll provided in this application embodiment;

[0042] Figure 4 This is a schematic diagram of the pressing process of the convex roller in a design method for a gradually curvature convex roller provided in an embodiment of this application;

[0043] Figure 5 This is a schematic diagram of the width-direction water flow density of the billet in each zone of the secondary cooling zone in a design method for a gradually curvature convex roller provided in this application embodiment;

[0044] Figure 6 This is the secondary cooling zone where the morphology of the billet solidification front is located in the design method of a gradually curvature convex roll provided in the embodiments of this application;

[0045] Figure 7 This refers to the deformation amount of the final solidification point corresponding to different boss lengths in the design method of a gradually curvature convex roller provided in this application embodiment;

[0046] Figure 8 This application provides a design method for a gradually curvature convex roller, which describes the resistance of the compaction blank corresponding to different boss lengths of the convex roller.

[0047] Figure 9 This application provides a design method for a gradually curvature convex roller, which describes the magnitude of the pressing force corresponding to different boss heights and gradient zones of the convex roller.

[0048] Figure 10 This refers to the magnitude of the surface peak stress corresponding to different boss heights and gradient zones in a design method for a gradually curvature convex roller provided in this application embodiment. Detailed Implementation

[0049] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0051] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] This invention provides a design method for a gradually curvature convex roller, see [link to relevant documentation]. Figure 1 The convex roll includes a roll body, a boss, and a gradient zone. The design parameters of the convex roll include the boss length, boss height, and gradient length. The specific steps include first obtaining the water flow density in the secondary cooling zone and calculating the convective heat transfer coefficient based on the water flow density. Based on the water flow density and convective heat transfer coefficient, the final solidification position of the billet is determined. Next, the deformation and billet resistance corresponding to the final solidification position for different boss lengths under the same reduction are obtained. When the billet resistance is less than or equal to a preset parameter, the boss length corresponding to the maximum deformation at the final solidification position is selected. The preset parameter is the ultimate output pressure of the continuous casting machine. Then, based on the target reduction, multiple sets of boss heights and gradient lengths are obtained. The peak stress and billet resistance on the billet surface corresponding to each set of boss heights and gradient lengths are calculated. When the billet resistance is less than or equal to the preset parameter, the boss height and gradient length corresponding to the minimum peak stress on the billet surface are selected. Finally, the convex roll with gradient curvature is machined based on the boss length, boss height, and gradient length.

[0053] The design method of the gradually curvature convex roll provided by this invention obtains the morphology of the solidification front of the billet to determine the final solidification position, and calculates data such as the peak stress and pressing resistance of the billet surface. At the same time, the design parameters of the gradually curvature convex roll are determined based on three criteria: maximizing the core deformation of the billet, minimizing the peak value of the billet surface, and not exceeding the limit output pressure of the continuous casting machine. This method can effectively increase the reduction of the continuous casting machine, improve the centerline segregation, and is applicable to convex rolls in cases where the width of the non-uniform solidified liquid core is less than the length of the boss, thus having strong applicability.

[0054] Specifically, to obtain the deformation and compact resistance at the final solidification position corresponding to different boss lengths under the same reduction, the gradient m of the transition zone can be defined, where m = L. GC / H PC L GC For a gradually changing length, H PCThe boss height is used as the reference. Then, based on the target reduction amount, different gradient lengths and boss heights are designed for the unit. The peak stress and pressing resistance of the billet surface for each group of shape parameters are calculated. Under the premise that the pressing resistance does not exceed the equipment's limit output pressure, the group with the smallest peak stress on the billet surface is selected.

[0055] Specifically, in the above embodiments, obtaining the water flow density in the secondary cooling zone includes: firstly, connecting the inlet of the continuous casting machine nozzle to a water source and an air pump, such that the height distance between the top of the continuous casting machine nozzle and the water pipe is equal to the vertical distance from the continuous casting machine nozzle to the surface of the billet, thereby allowing the water sprayed from the continuous casting machine nozzle to flow into the water pipe; then, determining the water volume distribution of the continuous casting machine nozzle based on the water height in the water pipe; and finally, superimposing the water volume distributions of all continuous casting machine nozzles in the width direction of the billet to obtain the water flow density of the secondary cooling zone in the width direction. In this embodiment, by connecting the water source and the air pump, a certain water pressure and air pressure are applied to the continuous casting machine nozzle, so that the water sprayed from the nozzle can be received by the connected water pipe. The water volume distribution of a single nozzle is obtained based on the water height in the water pipe, and the water volume distributions of all nozzles in the width direction of the billet are superimposed to obtain the water flow density of the secondary cooling zone.

[0056] Specifically, the secondary cooling zone, also known as the post-secondary cooling zone, refers to the research on equipment modification, secondary cooling processes, and secondary cooling water distribution in the secondary cooling zone. This can reduce the accident rate and enable the mechanical equipment to operate efficiently. The effectiveness of controlling the cooling temperature of the billet in the secondary cooling zone directly affects the quality of the billet. Therefore, for continuously cast billets of different specifications, the zoning of the cooling water, the spray angle, the nozzle distance, and the water pressure must be appropriately adjusted. The nozzles must be properly placed to ensure that the cooled billet achieves a uniform or nearly uniform surface temperature around its perimeter on the same plane.

[0057] Specifically, in the above embodiments, the convective heat transfer coefficient is calculated based on the water flow density, including: calculating the convective heat transfer coefficient using the following formula:

[0058] h i spary＝ a i W i 0.55 (1-0.075T w )

[0059] Among them, h i spary Let be the convective heat transfer coefficient, i be the secondary cooling zone, and a be the convective heat transfer coefficient. i For continuous casting machine parameters, W i T is the water flow density. w This refers to the water temperature in the secondary cooling zone.

[0060] In this embodiment, the convective heat transfer coefficient can be calculated from the obtained water flow density. The convective heat transfer coefficient is an indicator characterizing the strength of the convective heat transfer process and is related to factors such as fluid properties, flow state, temperature, tube arrangement in the tube bundle, scouring method, and tube wall temperature. Using the obtained water flow density and the calculated convective heat transfer coefficient, the heat flux density of the secondary cooling zone can be calculated first. Then, based on the calculated heat flux density, the solidification front morphology of the non-uniform solidification of the billet can be determined, thereby obtaining the distance from the final solidification point to the center of the billet.

[0061] Specifically, in the above embodiments, obtaining the deformation and compact resistance at the final solidification position corresponding to different boss lengths under the same reduction amount includes: firstly, calculating the thermodynamic behavior of the convex roll pressing process with different design parameters based on a three-dimensional thermodynamic coupling model of convex roll pressing; and then, calculating the deformation and compact resistance at the final solidification position corresponding to different boss lengths under the same reduction amount based on the thermodynamic behavior. In this embodiment, by establishing a three-dimensional thermodynamic coupling model of convex roll pressing to calculate the thermo / mechanical behavior of the convex roll pressing process with different structural parameters, the deformation and compact resistance at the final solidification position corresponding to different boss lengths under the same reduction amount can be accurately calculated.

[0062] Specifically, in the above embodiments, before processing the gradient curvature convex roller according to the boss length, boss height, and gradient length, the method further includes: determining the parametric equation of the third-order Bethesda curve of the gradient region according to the boss height and gradient length, as shown in the following formula:

[0063] x(t)=L GC t 3 -3 / 2L GC t 2 +3 / 2L GC t(0≤t≤1)

[0064] y(t)=-2H PC t 3 +3H PC t 2 (0≤t≤1)

[0065] Among them, L GC For a gradually changing length, H PC This represents the height of the boss.

[0066] In this embodiment, after obtaining the boss height and gradient length, the third-order Bethesda curve of the gradient zone can be determined. The third-order Bethesda curve requires selecting four points on different lines in the plane and connecting them sequentially with line segments. The resulting third-order Bethesda curve is the outer shape curve of the gradient curvature convex roller boss and the gradient zone.

[0067] Furthermore, the process of machining a gradient curvature convex roller based on the boss length, boss height, and gradient length includes: keeping the diameter of the boss length portion constant, and cutting both sides of the roller body according to the parametric equation of the third-order Bethesda curve of the gradient zone, wherein the diameter of the boss is D. roll The diameter of the roller body is D roll -2H PC In this embodiment, the diameter of the length portion of the boss remains unchanged at D. roll The height of the boss is H. PC Therefore, the diameter of the roller body is the diameter D of the length of the boss. roll Subtracting the height of the two bosses, the coordinates of each point on the curve of the gradient region satisfy the parametric equation of the third-order Bethesda curve.

[0068] Specifically, in the above embodiments, after obtaining the water flow density in the secondary cooling zone and calculating the convective heat transfer coefficient based on the water flow density, and determining the final solidification position of the billet based on the water flow density and the convective heat transfer coefficient, the method further includes: obtaining the pressing sector segment where the final solidification position is located based on the final solidification position, and setting the pressing sector segment as a modified sector segment of the convex roller. In this embodiment, the inner arc side roller of the sector segment is processed into a gradually curvature convex roller, while the outer arc side remains a flat roller, which can be pressed down normally as a flat roller without movement.

[0069] Furthermore, the fan-shaped section covers the region with a solidity of 0.85-1 at the final solidification location. In this embodiment, during the continuous casting process, the change in solidity during the solidification of steel from liquid to solid is the most important process parameter and a decisive factor in determining the quality of the cast billet. It is also an important parameter for studying light reduction. As can be seen from the calculation formula, the central solidity is related to the temperature at the center point of the cast billet. Therefore, the region with a solidity of 0.85-1 is selected as the modified fan-shaped section of the convex roll.

[0070] Specifically, in the above embodiments, after machining the gradually curvature convex roller according to the boss length, boss height, and gradually changing length, the method further includes: assembling the gradually curvature convex roller onto the modified sector segment of the convex roller. In this embodiment, after obtaining the modified sector segment of the convex roller, the machined gradually curvature convex roller is assembled onto the modified sector segment of the convex roller and applied to the pressing process of the casting billet.

[0071] Specifically, see Figures 2 to 10 The present application provides a specific embodiment of a gradually curvature convex roller designed using the above-described design method:

[0072] Taking the continuous casting of 2200×300mm cross-section wide and thick slabs to produce 45# steel in a steel plant as an example:

[0073] 1. Based on the nozzle arrangement of the continuous casting machine and the water volume in the secondary cooling zone, calculate the water flow density in the width direction of the billet, such as... Figure 5 As shown, the solidification front morphology of the billet was calculated based on this. The final solidification point P was 762 mm from the center of the billet. Based on the complete solidification position of the final solidification point P, the modified section of the convex roll was determined to be 14 segments, as shown. Figure 6 As shown.

[0074] 2. Based on the continuous casting machine parameters and operating conditions, establish a three-dimensional thermo-mechanical coupling model of the billet roll pressing process. The pressing amount is 7mm. Calculate the deformation of point P for different boss lengths, as follows: Figure 7 As shown. When the boss length is less than 1720, the deformation at point P increases with the increase of the boss length. The compaction resistance for different boss lengths is as follows. Figure 8 As shown. The maximum allowable boss length of the equipment is 1705.6 mm, therefore the boss length L is determined. PC =1700mm.

[0075] 3. Design the height H of the boss PC : 10, 15, 20 mm, gradient m: 1.5, 2, 2.5, 3, 3.5, 4. A total of 18 sets of comparison parameters, the compact resistance of each set is as follows: Figure 9 As shown, the peak surface stress is as follows Figure 10 As shown in the figure, the group with the lowest surface stress, under the premise of not exceeding the maximum output pressure of the equipment, is H. PC =15mm, m=3(H) PC =15mm,L GC =45).

[0076] 4. The convex roller is processed according to the optimal shape parameters of the design. After being assembled into the inner arc side of the 14th segment, the single-segment reduction is increased from the original 4.5mm to 7mm. The improvement effect of the center segregation and center porosity of the billet before and after use is very obvious.

[0077] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method of designing a convex roll of progressive curvature, the convex roll comprising a roll body, a land and a progressive zone, the design parameters of the convex roll comprising a land length, a land height and a progressive length, characterized in that, The method comprises: obtaining the water flow density of the secondary cooling zone, and calculating the convective heat transfer coefficient according to the water flow density, and determining the final solidification position of the casting blank according to the water flow density and the convective heat transfer coefficient; obtaining the deformation amount and the billet resistance corresponding to the final solidification position of different boss lengths under the same reduction amount, and selecting the boss length corresponding to the maximum deformation amount of the final solidification position when the billet resistance is less than or equal to a preset parameter, wherein the preset parameter is the limit output pressure of the continuous casting machine; obtaining a plurality of groups of boss heights and gradual length changes according to a target reduction amount, calculating the peak stress of the casting blank surface and the billet resistance corresponding to each group of boss heights and gradual length changes, and selecting the boss height and gradual length change corresponding to the minimum peak stress of the casting blank surface when the billet resistance is less than or equal to a preset parameter; processing the gradually changing curvature convex roller according to the boss length, the boss height and the gradual length change.

2. The method of claim 1, wherein, The method comprises: connecting the water inlet of the continuous casting machine nozzle with the water source and the air pump, so that the top height distance of the continuous casting machine nozzle and the water pipe is equal to the vertical distance from the continuous casting machine nozzle to the surface of the casting blank, so that the water sprayed by the continuous casting machine nozzle flows into the water pipe; determining the water distribution of the continuous casting machine nozzle according to the height of the water in the water pipe; superimposing the water distribution of all the continuous casting machine nozzles in the width direction of the casting blank to obtain the water flow density of the secondary cooling zone in the width direction.

3. The method of claim 1, wherein, The method comprises: applying the following formula to calculate the convective heat transfer coefficient: wherein, is the convective heat transfer coefficient, i is the secondary cooling zone, a i is the caster parameter, W i is the water flow density, T w is the water temperature of the secondary cooling zone.

4. The method of claim 1, wherein, The method comprises: calculating the thermal mechanical behavior law of the convex roller reduction process of different design parameters according to the three-dimensional thermal mechanical coupling model of the convex roller reduction; calculating the deformation amount and the billet resistance corresponding to the final solidification position of different boss lengths under the same reduction amount according to the thermal mechanical behavior law.

5. The method of claim 1, wherein, Before the method of processing the gradually changing curvature convex roller according to the boss length, the boss height and the gradual length change, the method further comprises: determining the parameter equation of the third-order Bezier curve of the gradual change zone according to the boss height and the gradual length change as follows: x(t) = L GC t 3 -3 / 2L GC t 2 +3 / 2L GC t (0≤t≤1) y(t) = -2H PC t 3 + 3H PC t 2 (0≤t≤1) wherein L GC is the progression length, H PC is the boss height.

6. The method of claim 5, wherein, The method comprises: The diameter of the boss length part is kept unchanged, and the two sides of the roll body are cut according to the parametric equation of the three-order Bezier curve of the gradual change area, wherein the diameter of the boss is D roll , the diameter of the roll body is D roll -2H PC .

7. The method of claim 1, wherein, After the method of obtaining the water flow density of the secondary cooling zone, and calculating the convective heat transfer coefficient according to the water flow density, and determining the final solidification position of the casting blank according to the water flow density and the convective heat transfer coefficient, the method further comprises: obtaining the reduction fan-shaped section where the final solidification position is located according to the final solidification position, and setting the reduction fan-shaped section as the modified fan-shaped section of the convex roller.

8. The method of claim 7, wherein, The reduction fan-shaped section covers the region with a solid phase rate of 0.85-1 of the final solidification position.

9. The method of claim 7, wherein, After the method of processing the gradually changing curvature convex roller according to the boss length, the boss height and the gradual length change, the method further comprises: The gradually curving convex roll is assembled to the modified sector segment of the convex roll.

Images