JP2009178753A - Manufacturing method of thick steel plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a thick steel plate capable of enhancing the yield while suppressing generation of any flaw. <P>SOLUTION: The manufacturing method of the thick steel plate includes: a growth increment calculating step of calculating the growth increment of the minimum fish-tail by using the elongation ratio; a total edging amount calculating step of calculating the total edging amount during the edge-rolling in which the growth increment of the fish tail of the thick steel plate when ending the finish rolling is set to be larger than the minimum value; an edging amount specifying step of specifying the edging amount of the outgoing path and that of the incoming path by distributing the calculated total edging amount into the edging amount of the outgoing path in the edge-rolling and that of the incoming path in the edge-rolling so that the edge drops at front and rear ends in the longitudinal direction of the thick steel plate when ending the finish rolling are substantially same; and an edge-rolling step of performing the edge-rolling with the edging amount of the outgoing path and that of the incoming path. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a thick steel plate, and in particular, edging rolling in a sheet width direction (hereinafter referred to as “edger rolling”) using a rolling mill having a roll (hereinafter referred to as “edger rolling mill”). And horizontal rolling in the thickness direction using a rolling mill having a horizontal roll (hereinafter sometimes referred to as “horizontal rolling mill” or “rolling mill”) (hereinafter simply referred to as “rolling”). And a method of manufacturing a thick steel plate for controlling the planar shape.

  A thick steel plate is obtained by performing tenth rolling or finish rolling on a slab heated to a predetermined temperature in a heating furnace, after performing multiple-pass forming and rolling using a roughing mill and / or a finish rolling mill. The steel sheet is finished to a predetermined thickness (hereinafter, the thick steel plate at this point is referred to as “rolled finished thick steel plate”). The rolled steel plate finished through this process has various planar shapes (for example, a drum shape and a drum shape) due to the influence of rolling conditions and the like. And it is set as the thick steel plate which has a predetermined dimension by cut | disconnecting the shape-defective part of the edge part of a rolling finished thick steel plate.

  During the production of thick steel plates, edger rolling using an edger rolling mill is performed during the tenth rolling, before the finish rolling after rolling the rolled material 90 ° through 90 °, and / or during the final rolling. Sometimes done. This edger rolling is performed for the purpose of reducing the shape defect portion at the end, and the yield can be improved by controlling the planar shape of the thick steel plate through the edger rolling.

  Several techniques aimed at controlling the planar shape of a thick steel plate have been disclosed so far. For example, Patent Document 1 discloses a thick steel plate rolling method in which edging by an edger is continuously performed for one or more reciprocating passes, and then horizontal rolling is performed, and the required edging amount, the size of the steel plate during edging, and edging Based on the horizontal rolling conditions of the subsequent first pass, the necessary edging amount is distributed to each pass so that the fishtail length of the steel plate after horizontal rolling is the same at the front and rear ends and both sides in the rolling direction. A method of rolling a thick steel plate is disclosed. In addition, Patent Document 2 controls the position of the bevel that occurs on the back surface of the thick steel plate, prevents the beard from entering the thick steel plate after the crop cutting, and reduces the work load in the refining process. A technique relating to a thick plate anti-scaling rolling method for reducing and improving yield is disclosed.

JP-A-9-47803 JP-A-9-38701

  According to the technique disclosed in Patent Document 1, since the length of the fishtail can be made substantially the same at the front and rear ends, the planar shape can be made closer to a rectangle. Therefore, it is possible to reduce the truncation loss at the time of commercialization, which is considered to be a very effective method. However, even using the technique disclosed in Patent Document 1, depending on the manufacturing conditions, the width of the front and rear ends in the longitudinal direction is narrower than the width of the longitudinal direction stationary part of the slab, so-called “width drop” (hereinafter referred to as “ There is a possibility that the difference between the front and rear ends of the “width reduction amount” is increased (see FIG. 9). If the difference between the leading and trailing edges of the width drop becomes large, the product width cannot be secured, and the product falls, and if a large margin is given at the time of slab design for the purpose of preventing the drop, the yield tends to deteriorate. Therefore, the technique disclosed in Patent Document 1 has a problem that it is difficult to improve the yield while preventing degradation.

  On the other hand, according to the technique disclosed in Patent Document 2, it is possible to escape the “hege wrinkles” generated in the vicinity of the front and rear end corners of the thick steel plate to the cut-off portion, and there is a situation in which wrinkles exist in the product after the crop cutting Can be avoided. However, depending on the rolling conditions, the generation of wrinkles can be suppressed without securing a crop difference of 100 mm or more. Therefore, the technique disclosed in Patent Document 2 has adverse effects such as a decrease in productivity and a decrease in yield. There was a problem that it was easy to invite. Conversely, it was found that there are some conditions where it is difficult to avoid wrinkles when the crop difference is 100 mm.

  Then, this invention makes it a subject to provide the manufacturing method of the thick steel plate which can improve a yield, suppressing generation | occurrence | production of the wrinkles which enter into a product.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appropriately added in parentheses, but the present invention is not limited to the illustrated embodiments.

  1st this invention is a manufacturing method of a thick steel plate which manufactures a thick steel plate through tentering rolling, edging rolling by a reciprocating pass, and finish rolling, Comprising: The minimum fishtail growth amount using elongation length ratio Calculating the growth amount calculation step, and calculating the total width reduction amount in the edging rolling so that the fishtail growth amount of the thick steel plate at the end of finish rolling is equal to or greater than the minimum fishtail growth amount. The calculation step is calculated so that the width drop at the front end in the longitudinal direction of the thick steel plate at the end of finish rolling is substantially the same as the width drop at the rear end in the longitudinal direction of the thick steel plate at the end of finish rolling. The above-mentioned total width reduction amount is allocated to the width reduction amount of the forward pass in edging rolling and the width reduction amount of the return pass in edging rolling, and the width reduction amount of the forward pass and the width reduction amount of the return pass are obtained. Identify A width reduction amount specifying step, and an edging rolling step of performing edging rolling under the width reduction amount of the forward pass and the width reduction amount of the return pass, and manufacturing a thick steel plate Is the method.

  Here, in the first present invention and the present invention shown below (hereinafter, these may be collectively referred to as “the present invention”), the “growth amount calculating step” means at the end of rolling (cutting When the length of the previous steel plate is A and the length of the slab is B, the minimum fishtail growth amount that the steel plate should have using the stretch length ratio X specified by X = A / B Is a step of calculating. Furthermore, in the first aspect of the present invention, the “total width reduction amount calculating step” means C as the fishtail growth amount of the thick steel plate at the end of finish rolling, and Y as the minimum fishtail growth amount calculated in the growth amount calculation step. , It means a step of calculating a total width reduction amount in edging rolling such that C ≧ Y. Furthermore, in the present invention, the “total width reduction amount” means the sum of width reduction amounts in edging rolling by reciprocating passes. Furthermore, in the first aspect of the present invention, the “width reduction amount specifying step” means that the calculated total width reduction amount is D, the width reduction amount of the forward pass in edging rolling is D1, and the width reduction amount of the reverse pass in edging rolling Is D2 so that the width drop amount at the front and rear ends in the longitudinal direction of the thick steel plate at the end of finish rolling is substantially the same, and D = D1 + D2, 0 ≦ D1 ≦ D, and 0 ≦ D2 ≦ D The process of allocating D to D1 and D2 and specifying D1 and D2 is as follows. In the present invention, the “outward path” means an edging rolling path from one side to the other, and the “return path” means an edging rolling path from the other side to one side.

  2nd this invention is a manufacturing method of a thick steel plate which manufactures a thick steel plate through tentering rolling, edging rolling by multiple reciprocating passes, and finish rolling, Comprising: The minimum fish is used using a stretch length ratio. Calculating a tail growth amount, calculating a growth amount calculation step, and making the fish tail growth amount of the thick steel plate at the end of finish rolling equal to or greater than the minimum fish tail growth amount, and calculating the total total width reduction amount in edging rolling, Total width reduction amount calculation step, total width reduction amount determination step for determining the total width reduction amount in each of a plurality of reciprocating passes, and width drop at the front end in the longitudinal direction of the thick steel plate at the end of each reciprocating pass The total width reduction amount is the same as the width reduction amount of the forward path in each reciprocating path, so that the amount and the width drop amount at the rear end in the longitudinal direction of the thick steel plate at the end of each reciprocating path are substantially the same. And each The width reduction amount of the forward path, the width reduction amount of the forward path, and the width reduction amount of the backward path, the width reduction amount of the forward path, and the An edging rolling step of performing the edging rolling under a width reduction amount of a reverse pass.

  Here, in the second aspect of the present invention, the “total total width reduction amount calculation step” means E as the fishtail growth amount of the thick steel plate at the end of finish rolling, and the minimum fishtail growth amount calculated in the growth amount calculation step. When Y is Y, it means a step of calculating the total total width reduction amount in edging rolling such that E ≧ Y. Furthermore, in the second aspect of the present invention, the “total total width reduction amount” means the sum of width reduction amounts in edging rolling by a plurality of reciprocating passes. Furthermore, in the second aspect of the present invention, the “width reduction amount specifying step” refers to the determined total width reduction amount of edging rolling by each reciprocating pass Gn (n is a natural number; the same applies hereinafter), and each reciprocating pass. When the width reduction amount of the forward pass in edging rolling by In is set to In and the width reduction amount of the return pass in edging rolling by each reciprocating pass is Jn, at the end of edging rolling by each reciprocating pass (the edging rolling by the reciprocating pass is When n times are provided, when the edging rolling by the n-th reciprocating pass is completed, the same applies hereinafter), the width drop amount at the front and rear ends in the longitudinal direction of the thick steel plate is substantially the same, and Gn = In + Jn , 0 ≦ In ≦ Gn, 0 ≦ Jn ≦ Gn (G, I, J subscripts n are the same, the same applies hereinafter), and Gn is distributed to In and Jn, and each round trip path Identifying a width reduction amount In and Jn edging rolling by means.

  According to the first aspect of the present invention, there is provided an edging rolling process that is performed while ensuring a fishtail growth amount of a certain amount or more and controlling the width drop amount at the front and rear ends in the longitudinal direction of the thick steel plate to be substantially the same. Therefore, it is possible to provide a method for producing a thick steel plate capable of improving the yield while suppressing the generation of wrinkles that enter the product.

  According to the second aspect of the present invention, even when edging rolling is performed by a plurality of reciprocating passes, a fishtail growth amount of a certain amount or more is ensured, and the width drop at the front and rear ends in the longitudinal direction of the thick steel plate Since an edging rolling process is performed while controlling the amounts so as to be substantially the same, it is possible to provide a method of manufacturing a thick steel plate capable of improving yield while suppressing generation of wrinkles entering the product. it can.

  As a result of intensive studies, the present inventors have found that the occurrence of wrinkles can be suppressed depending on rolling conditions without securing a crop difference of 100 mm or more. Furthermore, in order to improve the yield while suppressing wrinkles, it has been found that it is important to obtain a certain amount of fishtail shape as shown in FIG. In addition, when the relationship between the stretch length ratio and fishtail growth amount and the occurrence of wrinkles was investigated, the fishtail growth amount (Fig. 1 It was found that it is possible to prevent the occurrence of wrinkles in the product by ensuring a reference value or more (see FIG. 2). As described above, the present invention has been completed by discovering that it is possible to suppress wrinkles and improve yield by securing a fishtail growth amount of a certain value or more according to the value of the stretch length ratio. .

  The inventors of the present invention newly created a planar shape prediction model of a thick steel plate capable of considering the asymmetry of the front and rear ends in order to examine edger conditions that minimize width drop while ensuring an appropriate crop shape. . Conventionally, many models for predicting the planar shape of thick steel plates have been reported, especially edger rolling in a reciprocating pass by a thick plate rolling mill having a detached edger where the edger rolling mill is separated from the horizontal rolling mill. As a method for predicting the planar shape in the case of performing, the mainstream method is to predict without distinguishing the forward pass and the reverse pass edger rolling in the reciprocating pass. However, if the planar shape of the thick steel plate is predicted by such a method, it is difficult to predict the planar shape of the front and rear ends of the thick steel plate with high accuracy. It was difficult to accurately predict the amount of change in the amount of the drop. Therefore, the present inventors can predict the planar shape of the leading end and the trailing end of the thick steel plate with high accuracy by newly performing a hot rolling experiment. A model for predicting the planar shape of thick steel plates that can be accurately predicted independently at the front and rear ends was constructed. The main points of the constructed model are shown below.

1-a. The width drop change amount in the forward pass edger rolling is calculated independently at the front and rear ends. In addition, the crop-shaped growth amount after the forward pass edger rolling (hereinafter, “crop-shaped growth amount” may be referred to as “crop growth amount”) is calculated independently at the leading and trailing edges.
1-b. The width drop change amount in the rear pass edger rolling is calculated independently for the leading and trailing edges, and the crop growth amount after the backward pass edger rolling is calculated independently for the leading and trailing edges, and the calculated width drop change amount and the crop growth amount are calculated as above. 1-a. Is linearly added to the result of.
2. While calculating the width drop change amount by virtual rolling which rolls only the rising part (henceforth a "dogbone part") near the width | variety edge part which generate | occur | produced by edger rolling, the crop amount after the said virtual rolling is set to x, When the crop amount after edger rolling performed before the virtual rolling is y, the crop growth amount represented by xy is calculated, and the 1-b. Is linearly added to the result of.
3. 1. Calculate the width drop change amount and crop growth amount in horizontal rolling. Is linearly added to the result of.

  Hereinafter, details of the constructed model (a model for predicting a planar shape when horizontal rolling is performed after edger rolling) will be described.

1. Point 1-a and Point 1-b
The width drop change amount ΔWE in edger rolling can be calculated by the following formulas 1 and 2.
Tip side: ΔWE = f1 (W, ΔV, H, RE, ΔW0) (Formula 1)
Rear end side: ΔWE = f2 (ΔV, ΔW0) (Formula 2)
Here, W is a sheet width, ΔV is a width reduction amount (a reduction amount in the sheet width direction), H is a sheet thickness, RE is a roll diameter of an edger rolling mill, ΔW0 is an initial width drop change amount, and f1 and f2 are functions. It is.

The crop growth amount ΔLE after edger rolling can be calculated by the following formulas 3 and 4.
Tip side: ΔLE = f3 (ΔWE) (Formula 3)
Rear end side: ΔLE = f4 (ΔV) (Formula 4)
Here, f3 and f4 are functions.

  In addition, after the second pass (when the edging rolling is performed by one round-trip pass, the return pass, and when the edging rolling is performed by a plurality of continuous round-trip passes, after the first pass of the round-trip pass) In the case of edger rolling in the following cases, the width reduction amount and the crop amount after completion of edger rolling are linearly added to the planar shape obtained from the width drop change amount and crop growth amount after edger rolling in each pass. Ask for. In the calculation of the width drop change amount after the second pass, the width drop shape obtained by the calculation up to the previous pass is calculated as the initial shape (ΔW0).

Subsequently, the change amount ΔWE (xL) of the width reduction profile after the edger rolling can be calculated by the following equation 5.
ΔWE (xL) = f5 (ΔWE, xL, RE) (Formula 5)
Here, xL is the distance from the material tip, and f5 is a function.

Further, the change amount ΔLE (xW) of the crop profile after the edger rolling can be calculated by the following formula 6.
ΔLE (xW) = f6 (ΔLE, xW, H, ΔV) (Expression 6)
Here, xW is a distance from the center of the plate width, and f6 is a function.

2. Key point 2
The planar shape change after the edger rolling is the planar shape change (main point 2) when only the dog bone portion generated by the edger rolling is rolled (hereinafter sometimes referred to as “HD rolling”), and there is no dog bone portion. Calculation is performed by adding the planar shape change (main point 3) when the steel plate in a state is rolled.

The width drop change amount ΔWD generated by HD rolling can be calculated by the following equation (7).
ΔWD = f7 (CME, ΔV, ΔW0) (Expression 7)
Here, f7 is a function determined in consideration of the edger rolling direction and the HD rolling direction. CME is a rising width spread coefficient in HD rolling, and can be calculated by the following formula 8.
CME = f8 (W, H, ΔV, RE, ΔW0) (Formula 8)
Here, f8 is a function.

The crop growth amount ΔLD in HD rolling can be calculated by the following formula 9 using the width drop change amount ΔWD in HD rolling.
ΔLD = f9 (ΔWD) (Formula 9)
Here, f9 is a function.

Further, the width drop profile change amount ΔWD (xL) in HD rolling can be calculated by the following formula 10, and the crop profile change amount ΔLD (xW) in HD rolling can be calculated by the following formula 11. .
ΔWD (xL) = f10 (ΔWD, xL, RE) (Equation 10)
ΔLD (xW) = f11 (ΔLD, xW, H, ΔV) (Formula 11)
Here, f10 and f11 are functions.

3. Key point 3
The prediction formula of the planar shape change amount when the rolled material (steel plate) without the dogbone portion is horizontally rolled will be described below.
Unlike edger rolling, the width end near the front and rear ends of the material to be rolled during horizontal rolling is deformed so as to project outward from the sheet width center. The amount ΔWR projecting outward can be calculated by the following equation 12.
ΔWR = f12 (R, ΔH, H) (Formula 12)
Here, R is the roll diameter of the horizontal rolling mill, ΔH is the amount of reduction (the amount of reduction in the sheet thickness direction), and f12 is a function.

On the other hand, in horizontal rolling, deformation in a form in which the central portion in the width direction projects forward occurs, and the crop shape becomes a shape corresponding to the deformation. The forward protrusion amount ΔLR in the modification of the above-described forward protrusion form can be calculated by the following equation (13).
ΔLR = f13 (R, ΔH, H) (Formula 13)
Here, f13 is a function.

Further, the width drop profile change amount ΔWR (xL) in horizontal rolling can be calculated by the following formula 14, and the crop profile change amount ΔLR (xW) in horizontal rolling can be calculated by the following formula 15.
ΔWR (xL) = f14 (ΔWR, xL, R) (Formula 14)
ΔLR (xW) = f15 (ΔLR, xW) (Formula 15)
Here, f14 and f15 are functions.

When horizontal rolling is performed, the material to be rolled is stretched in the longitudinal direction, so that the shape of the crop generated up to the previous pass also changes. In this model, it is assumed that the crop shape grown up to the previous pass grows as much as the reduction, and the crop growth amount ΔL ⁿ (xW) after n passes is calculated by the following equation (16).
ΔL ⁿ (xW) = ΔLR ⁿ (xW) + L ⁿ⁻¹ (xW) × H ⁿ / H ⁿ⁻¹ (Expression 16)
Here, ΔLR ⁿ (xW) is the crop profile change amount generated in horizontal rolling of n passes, L ^n-1 (xW) is the crop profile after completion of n-1 passes, and H ⁿ is horizontal rolling of n passes. The subsequent plate thickness, H ^n−1, is the plate thickness after n−1 passes of horizontal rolling.

  By using the model described above, it is possible to predict the planar shape of the thick steel plate for all the steps of the thick plate rolling process including edger rolling based on the result calculated independently at the front and rear ends.

  Next, the embodiment of the present invention will be described while explaining the results of investigating the relationship between the edger rolling conditions, the fishtail growth amount, and the width drop change amount using the constructed model.

  3 and 4 show that the width reduction amount in the forward pass of edger rolling (hereinafter referred to as “deepening edging”) performed during the tenth rolling is fixed to 20 mm, and the width reduction amount in the reverse pass is fixed to 20 mm. In the case where edger rolling after completion of tentering rolling (hereinafter sometimes referred to as “finishing edging”) is performed immediately after the turn after completion of tentering rolling, under conditions where the width reduction amount of the forward pass and the reverse pass is equal. FIG. 3 shows the results of the relationship between the total width reduction amount of finishing edging and the width drop amount (FIG. 3) and the relationship between the total width reduction amount of finishing edging and the fishtail growth amount (FIG. 4). In FIG. 3 and subsequent figures, “Top” means a result on the front end side, and “Bot” means a result on the rear end side. Table 1 shows edger rolling conditions other than the width reduction amount.

  In Table 1 and the table shown below, “turn” means that the thick steel plate was turned 90 °, and “→” means the step of rolling to the plate thickness described in the right column of the table thereafter. That is, Table 1 shows the conditions when performing the tenter rolling and finish rolling on the slab having a thickness of 250 mm. The tenter rolling shown in Table 1 is performed by rolling a slab having a thickness of 250 mm by 90 °, then rolling until the plate thickness becomes 170 mm, then performing depressing edging, and thereafter until the plate thickness becomes 150 mm. The finish rolling described in Table 1 is performed by rolling, and after rolling the rolled material by 90 ° by the above-mentioned process, finishing edging is performed, and then the plate thickness becomes 130 mm. The content is to carry out rolling until.

  3 and 4, the sum of the width reduction amounts of the forward pass and the return pass, that is, as the total width reduction amount increases, the width drop amount increases, and the fishtail growth amount increases monotonously. Yes. Further, it can be seen from the results that when edger rolling is performed under the condition that the width reduction amount of the forward pass and the backward pass are equal, the width drop amount and the fish tail growth amount become asymmetric at the front and rear ends (FIGS. 3 and 4). Middle, Top, and Bot mean the front end and the rear end, respectively.)

  Therefore, a simulation was performed in which the total width reduction amount of finishing edging was fixed to 40 mm, and the distribution of width reduction amounts of the forward pass and the return pass was changed. The results are shown in FIGS. 5 and 6 show that the width reduction amount in the forward pass of the widening edging is fixed to 20 mm, the width reduction amount in the return pass is fixed to 20 mm, and the total width reduction amount of the finishing edging is fixed to 40 mm. When finishing edging is performed under conditions in which the distribution of the width reduction amount of the return pass is variously changed, the width reduction amount of the forward pass / the total width reduction amount (hereinafter referred to as “forward width reduction distribution ratio”) and the width drop. FIG. 5 shows the results of the relationship with the amount (FIG. 5) and the relationship between the forward width reduction distribution ratio and the fishtail growth amount (FIG. 6).

  From FIG. 5, the difference between the leading and trailing edges of the width drop amount greatly varies depending on the forward width reduction distribution ratio. According to FIG. 5, when the forward width reduction distribution ratio is less than 0.4, the width drop amount at the front and rear ends is equal. I understand that On the other hand, as shown in FIG. 6, the amount of fishtail growth also fluctuated depending on the forward width reduction distribution ratio, similar to the amount of decline. However, on the tip side where the fishtail growth amount is small, there is no significant change even if the forward width reduction distribution ratio changes. On the rear end side where the fishtail growth amount is large, the fishtail grows as the forward width reduction distribution ratio increases. The amount of growth has increased. As described above, in order to prevent wrinkles entering the product, it is necessary to secure a fishtail growth amount of a predetermined amount or more at both the front and rear ends. In this respect, the tip side with a small fish tail growth amount may be a problem, but from FIG. 6, the fish tail growth amount on the tip side is hardly affected by the forward width reduction distribution ratio. Therefore, it is considered that the forward width reduction distribution ratio may be determined so as to minimize the difference in the width drop amount on the front and rear end sides.

  In the above description regarding the embodiment of the present invention, the finish edging conditions have been mainly mentioned. However, in order to reduce the width drop amount, the influence of the width edging performed during the width rolling is also considered. It is still more preferable.

  Based on the above simulation results, we have devised an optimal edger condition determination method for effectively preventing wrinkles entering a steel plate product and improving yield. Hereinafter, the present invention will be described more specifically.

1. Manufacturing method of thick steel plate 1.1. First Embodiment FIG. 7 is a flowchart showing steps provided in a method for manufacturing a thick steel plate according to the first embodiment of the present invention (hereinafter sometimes referred to as “first manufacturing method”). As shown in FIG. 7, the first manufacturing method includes a growth amount calculation step (step S11), a total width reduction amount calculation step (step S12), a width reduction amount identification step (step S13), and an edging rolling step. (Step S14), and a thick steel plate is manufactured through Steps S11 to S14.

<Step S11>
Step S11 uses a stretched length ratio X specified by X = A / B, where A is the length of the thick steel plate at the end of rolling (before cutting) and B is the length of the slab. Is a step of calculating the minimum fishtail growth amount that should be possessed. The minimum fishtail growth amount Y calculated in step S11 can be obtained by the following equation 17, for example.
Y = 40 × X ^0.4 (Formula 17)

<Step S12>
Step S12 is an edging rolling in which C ≧ Y, where C is the fishtail growth amount of the thick steel plate at the end of finish rolling, and Y is the minimum fishtail growth amount calculated in the growth amount calculation step. This is a step of calculating the total width reduction amount. In step S12, for example, the width reduction amount of the reciprocating path is set to be equal, and the planar shape is calculated by substituting the rolling conditions into Equations 1 to 16, and the total width reduction in the edging rolling in which the necessary fishtail growth amount is obtained. It can be set as the process of calculating quantity. Here, the total width reduction amount in edging rolling means the total width reduction amount in finish edging.

<Step S13>
In step S13, when the total width reduction amount calculated in step S12 is D, the width reduction amount of the forward pass in edging rolling is D1, and the width reduction amount of the reverse pass in edging rolling is D2, when finishing rolling is finished. To D1 and D2 so that the width drop amounts at the front and rear ends in the longitudinal direction of the thick steel plate are substantially the same, and D = D1 + D2, 0 ≦ D1 ≦ D, and 0 ≦ D2 ≦ D. This is a step of assigning and specifying D1 and D2. Step S13, for example, assigns rolling conditions to Equations 1 to 16 to create a relationship diagram between the forward width reduction distribution ratio and the amount of width reduction as shown in FIG. By identifying the forward width reduction distribution ratio whose amount is substantially the same as the width drop amount at the rear end in the longitudinal direction of the thick steel plate, and distributing D to D1 and D2 based on the forward width reduction distribution ratio, D1 and It can be set as the process of specifying D2. When D1 = 0 or D2 = 0, the forward or backward finish edging is omitted.

<Step S14>
Step S14 is a step of performing edging rolling under the conditions of the width reduction amount D1 of the forward pass and the width reduction amount D2 of the backward pass specified in the step S13.

  Thus, according to the 1st manufacturing method which manufactures a thick steel plate through process S11 thru | or process S14, minimum fishtail growth amount Y is specified by process S11, and the specified minimum fishtail growth amount Y is used. Since the edging rolling is performed under the specified conditions that the width reduction amount of the forward pass is D1 and the width reduction amount of the return pass is D2, the thick steel plate capable of improving the yield while suppressing the occurrence of wrinkles Can be manufactured.

  Next, the manufacturing method of the thick steel plate of this invention concerning 2nd Embodiment is demonstrated concretely.

1.2. Second Embodiment FIG. 8 is a flowchart showing steps provided in a method for manufacturing a thick steel plate according to a second embodiment of the present invention (hereinafter, also referred to as “second manufacturing method”). As shown in FIG. 8, the second manufacturing method includes a growth amount calculation step (step S21), a total total width reduction amount calculation step (step S22), a total width reduction amount determination step (step S23), a width A reduction steel amount specifying step (step S24) and an edging rolling step (step S25) are provided, and a thick steel plate is manufactured through steps S21 to S25.

<Step S21>
In step S21, when the length of the thick steel plate at the end of rolling (before cutting) is A and the length of the slab is B, the thickness is determined using the stretch length ratio X specified by X = A / B. This is a step of calculating the minimum fishtail growth amount that the steel sheet should have. The minimum fishtail growth amount Y can be obtained by the following equation 17, for example.
Y = 40 × X ^0.4 (Formula 17)

<Step S22>
Step S22 is an edging rolling process in which E ≧ Y, where E is the fishtail growth amount of the thick steel plate at the end of finish rolling, and Y is the minimum fishtail growth amount calculated in the growth amount calculation step. This is a step of calculating the total total width reduction amount. In step S22, for example, the total width reduction amount ΔW of each finishing edging is set equal, and the planar shape is calculated by substituting the rolling conditions into Equations 1 to 16, and the total total width reduction amount satisfying E ≧ Y is determined. It can be set as the process to do. Here, the total total width reduction amount in edging rolling means the total total width reduction amount in finish edging by a plurality of reciprocating passes. Note that, if the number of edging passes is too large, productivity is hindered, so it is desirable that the finishing edging is usually limited to two times.

<Step S23>
In step S23, the total total width reduction amount calculated in step S22 is distributed to the total width reduction amount of each edging rolling by the reciprocating pass, which constitutes the edging rolling by the reciprocating pass, thereby making a plurality of times. It is a step of determining the total width reduction amount of each edging rolling constituting the edging rolling by the reciprocating pass. When edging rolling by a plurality of reciprocating passes is constituted by edging rolling by two reciprocating passes, the step S23 sets the width reduction amount in the forward pass and the width reduction amount in the return pass equally. The total width reduction amount calculated in step S22 is distributed to the total width reduction amount of the edging rolling by the first and second reciprocating passes, and the total width of the edging rolling by the first and second reciprocating passes. It can be a step of determining the amount of reduction.

<Step S24>
In step S24, the total width reduction amount of edging rolling by each round-trip pass determined in step S23 is Gn, the width reduction amount of the forward pass in edging rolling by each round-trip pass is In, and edging rolling by each round-trip pass When the width reduction amount of the return pass at Jn is Jn, the width drop amount at the front and rear ends in the longitudinal direction of the thick steel plate at the end of edging rolling by each reciprocating pass is substantially the same, and Gn = In + Jn, 0 In this step, Gn is distributed to In and Jn so that ≦ In ≦ Gn and 0 ≦ Jn ≦ Gn, and the width reduction amounts In and Jn of edging rolling by each reciprocating pass are specified. Step S23 uses, for example, FIG. 5 to identify the forward width reduction distribution ratio in which the width drop amount at the longitudinal direction front end of the thick steel plate is substantially the same as the width drop amount at the longitudinal direction rear end of the thick steel plate. By distributing Gn to In and Jn based on the width reduction distribution ratio, the process of specifying In and Jn can be performed.

<Step S25>
Step S25 is a step of performing edging rolling by a plurality of reciprocating passes under the conditions of the width reduction amount In of the forward pass and the width reduction amount Jn of the backward pass specified in Step S24.

  Thus, according to the 2nd manufacturing method which manufactures a thick steel plate through process S21 thru | or process S25, the minimum fishtail growth amount Y is specified by process S21, and the specified minimum fishtail growth amount Y is used. Since the edging rolling is performed under the specified conditions where the width reduction amount of the forward pass is In and the width reduction amount of the return pass is Jn, the thick steel plate capable of improving the yield while suppressing the occurrence of wrinkles Can be manufactured.

1. Evaluation test of influence of edger condition on planar shape Using the above-mentioned planar shape prediction model, a simulation was performed by changing the edger condition under the conditions of Mark: F01 to F03 shown in Table 2 below, and the change of the planar shape was investigated. did. In Table 2 below, “E1” means widening edging and “E2” means finish edging.

Table 3 below shows the results of the width reduction amount, the fishtail growth amount, and the width drop amount when the edger conditions determined according to the conditions shown in Table 2 and the first manufacturing method are applied. Summarized as 1. On the other hand, Table 3 below shows the results of the width reduction amount, the fishtail growth amount, and the width drop amount when the conditions shown in Table 2 and the edger conditions determined according to the second manufacturing method are applied. It was summarized as Invention Example 2. On the other hand, as Comparative Example 1, the minimum fishtail growth amount was fixed to 100 mm regardless of the stretch length ratio, and the conditions under which the width reduction amount of the finishing edging forward pass and the return pass were equally set were also calculated. 2, the calculation was also performed for the conditions in which the distribution of the width reduction amount was determined so that the minimum fishtail growth amount was fixed to 100 mm and the front and rear end fishtail growth amounts were the same regardless of the stretch length ratio. The rolling conditions and edger conditions of Example 1, Invention Example 2, Comparative Example 1, and Comparative Example 2 performed for each of Mark: F01 to F03 shown in Table 2 are shown in Table 3, and the results are shown in Table 3. 4 also shows. In Table 4, “FT growth amount” means “fishtail growth amount”, and “minimum FT growth amount” means “minimum fishtail growth amount”. Further, the minimum fishtail growth amount in Invention Examples 1 and 2 was calculated by the following formula 17 using the stretch length ratio X.
Y = 40 × X ^0.4 (Formula 17)

2. Results 2.1. F01
F01 is an edger condition in which the finished thickness of the thick steel plate is 15.8 mm and both the width ratio and the stretched length ratio are relatively large. In the case of F01, the minimum fishtail growth amount Y calculated by substituting 8.86 for X in the above equation 17 is 96 mm, and the edger condition is determined based on the first manufacturing method while ensuring the fishtail growth amount. In Example 1 of the present invention that determined the above, the width drop amount was 8 mm at both the front and rear ends. In addition, in Example 2 of the present invention in which the edger condition was determined based on the second manufacturing method while securing a fishtail growth amount of 96 mm, the width drop amount was significantly reduced, and both the front and rear ends were 3 mm.

  On the other hand, in Comparative Example 1 in which the distribution of the width reduction amount of the finishing edging is equal between the forward pass and the return pass, the width drop amount at the rear end is as large as 11 mm. Further, in Comparative Example 2 in which the distribution of the width reduction amount of the forward pass and the backward pass was determined so that the fishtail growth amounts at the front and rear ends were equal, the width drop amount at the tip was as large as 10 mm. That is, in Comparative Examples 1 and 2 that do not depend on the present invention, the yield is expected to deteriorate, and according to the present invention (Inventive Example 1 and Inventive Example 2), the yield can be improved. It was.

2.2. F02
F02 is an edger condition in which the finish thickness is 76 mm and the stretch length ratio is small. In the case of F02, the minimum fishtail growth amount Y calculated by substituting 2.17 for X in the above equation 17 is 55 mm, and the edger condition is based on the first manufacturing method while ensuring this fishtail growth amount. In Example 1 of the present invention that determined the above, the width drop amount was 8 mm at both the front and rear ends. Further, in Example 2 of the present invention in which the edger condition was determined based on the second manufacturing method while securing a fishtail growth amount of 55 mm, the width drop amount was remarkably reduced, and both the front and rear ends were 5 mm.

  On the other hand, in Comparative Example 1 in which the distribution of the width reduction amount of the finishing edging is equal between the forward pass and the return pass, the width drop amount at the rear end is as large as 15 mm. In addition, the fishtail growth amount was over 100 mm. Further, in Comparative Example 2 in which the distribution of the width reduction amount of the forward pass and the backward pass was determined so that the fish tail growth amounts at the front and rear ends were equal, the width drop amount at the tip was as large as 18 mm. That is, in Comparative Examples 1 and 2 that do not depend on the present invention, the yield is expected to deteriorate, and according to the present invention (Inventive Example 1 and Inventive Example 2), the yield can be improved. It was.

2.3. F03
F03 is an edger condition that is a thin material having a finish thickness of 8 mm and a large stretch length ratio. In the case of F03, the minimum fishtail growth amount Y calculated by substituting 18.75 for X in the equation 17 is 129 mm, and the edger condition is based on the first manufacturing method while ensuring this fishtail growth amount. In Example 1 of the present invention that determined the above, the width drop amount was 8 mm at both the front and rear ends. Further, in Example 2 of the present invention in which the edger conditions were determined based on the second manufacturing method while securing a fish tail growth amount of 129 mm, the width drop amount was remarkably reduced, and both the front and rear ends were 3 mm.

  On the other hand, in Comparative Example 1 in which the distribution of the width reduction amount of the finishing edging is the same in the forward pass and the backward pass, the leading end side is 8 mm and the trailing end side is 7 mm, which are substantially the same as those of the inventive example 1. However, the fish tail growth amount is 100 mm at the tip side, which is smaller than the necessary fish tail growth amount of 129 mm of the present invention. Further, in Comparative Example 2 in which the distribution of the width reduction amount of the forward pass and the backward pass was determined so that the amount of fishtail growth at the front and rear ends was equal, the width drop at the tip was 9 mm, and a slight deterioration in the yield was expected. In addition, since the fish tail growth amount was 110 mm, the occurrence of wrinkles in the product was a concern.

It is a figure which shows the definition of a fish tail growth amount (crop difference). It is a figure which shows the relationship between stretch length ratio and the amount of fishtail growth, and wrinkle generation | occurrence | production. It is a figure which shows the relationship between the total width reduction amount and width reduction amount. It is a figure which shows the relationship between the total width reduction amount and the fishtail growth amount. It is a figure which shows the relationship between the forward width reduction distribution ratio and the width drop amount. It is a figure which shows the relationship between the forward width reduction distribution ratio and the amount of fishtail growth. It is a flowchart which shows the form example of a 1st manufacturing method. It is a flowchart which shows the example of a form of a 2nd manufacturing method. It is a figure which shows the definition of width reduction amount.

Claims (2)

It is a manufacturing method of a thick steel plate that manufactures a thick steel plate through tentering rolling, edging rolling by a reciprocating pass, and finish rolling,
A growth amount calculating step for calculating a minimum fishtail growth amount using the stretch length ratio;
A total width reduction amount calculation step of calculating a total width reduction amount in the edging rolling, wherein the fishtail growth amount of the thick steel plate at the end of the finish rolling is equal to or greater than the minimum fishtail growth amount;
Calculation is performed so that the width drop amount at the front end in the longitudinal direction of the thick steel plate at the end of the finish rolling is substantially the same as the width drop amount at the rear end in the longitudinal direction of the thick steel plate at the end of the finish rolling. The total width reduction amount is allocated to the width reduction amount of the forward pass in the edging rolling and the width reduction amount of the return pass in the edging rolling, and the width reduction amount of the forward pass and the width of the return pass A width reduction amount specifying step for specifying a reduction amount;
An edging rolling step of performing the edging rolling under the width reduction amount of the forward pass and the width reduction amount of the return pass;
A method for producing a thick steel plate, comprising: It is a manufacturing method of a thick steel plate that manufactures a thick steel plate through tentering rolling, edging rolling by a plurality of reciprocating passes, and finish rolling,
A growth amount calculating step for calculating a minimum fishtail growth amount using the stretch length ratio;
A total total width reduction amount calculating step of calculating a total total width reduction amount in the edging rolling, wherein the fishtail growth amount of the thick steel plate at the end of the finish rolling is equal to or greater than the minimum fishtail growth amount,
A total width reduction amount determining step for determining a total width reduction amount in each of the plurality of round-trip passes;
The width drop amount at the front end in the longitudinal direction of the thick steel plate at the end of each reciprocating pass is substantially the same as the width drop amount at the rear end in the longitudinal direction of the thick steel plate at the end of each reciprocating pass. As described above, the total width reduction amount is allocated to the width reduction amount of the forward path in each of the reciprocating paths and the width reduction amount of the return path in each of the reciprocating paths, A width reduction amount specifying step for specifying a width reduction amount of the return path;
An edging rolling step of performing the edging rolling under the width reduction amount of the forward pass and the width reduction amount of the return pass;
A method for producing a thick steel plate, comprising:

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