JPS6150044B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a thick plate rolling method, and more particularly to a thick plate rolling method that makes the planar shape of the final product as close to a rectangle as possible and enables high-yield rolling with a small amount of side scrap, top and bottom crops. It is. In normal thick plate rolling, as shown in Fig. 1, a slab 1 extracted from a heating furnace is first passed through horizontal rolling in the longitudinal direction of the slab called a DBT pass to form a rolled material 2 with little change in thickness in the longitudinal direction. Then, this rolled material 2 is rotated 90 degrees in the horizontal plane with respect to the axial direction ←→ of the rolled material.
The rolled material 3 is rotated by 90 degrees and subjected to horizontal rolling for tentering, and then the rolled material 3 after tentering is turned again by 90 degrees and horizontally rolled until it reaches the final thickness, thereby completing the final product 4. By the way, if the shape of the final product 4 after the above-mentioned rolling process is a perfect rectangle, it is possible to effectively take the product from its entire length and width, but in reality, the slab 1 is passed through the DBT pass. As shown in FIG. 2, the subsequent rolled material 2 has a width overhang ΔW at the four corners, a crop ΔL at the top and bottom, and has an hourglass-shaped planar shape. The above-mentioned width extension ΔW and crop ΔL are further stretched by the next stage of tenter rolling and horizontal rolling, and the expanded state remains in the final product after finish rolling, so that the planar shape of the final product is not rectangular. in this case,
If the tenting ratio (product width/slab width) is small, the planar shape of the final product will have a tongue-like crop shape and a drum-like width precision defect, as shown in 4a and 4c in Figure 3.
On the other hand, if the tenting ratio is large, a fishtail-like crop shape and a drum-like width precision defect will occur as shown in 4b and 4d. Such defects in the planar shape of the final product increase the amount of scrap when taking the product and cause a significant drop in yield, so various measures have been taken to make the planar shape of the finished product as close to a rectangular shape as possible. has been considered. One of the most effective countermeasures is to correct the planar shape of the rolled material by applying pressure to the side surface of the rolled material using an edger (vertical roll) during the process of edge rolling, ie, thick plate rolling. Figure 4 shows an example of controlling the planar shape of the rolled material by the above-mentioned etching rolling.
After passing, the rolled material 2, which has become drum-shaped due to the width overhang ΔW and crop ΔL, is turned by 90 degrees in a horizontal plane, and is then etched on both sides in the width direction with edge rolls 5 and 5'. (referred to as rolling), thereby increasing the width overhang amount Δ of the rolled material 2
Increase W. This rolled material 2 is then subjected to horizontal tentering rolling to become a rolled material 3, but in this state, the width overhang ΔW at the four corners is large, so this rolled material 3 is further turned 90 degrees in the horizontal plane, That is, the longitudinal direction of the rolled material 3 is aligned with the longitudinal direction of the slab 1, and etching rolling is performed again with the edger rolls 5, 5' (referred to as L-direction etching rolling), and the above-mentioned large width overhang ΔW is applied in the leading and trailing directions. Correct the crop shape on both longitudinal sides by metal flow. Next, the rolled material 3 is passed through finishing horizontal rolling to become a finished product 4 with a finished thickness. In this way, etching rolling is performed in the middle of the horizontal rolling process, and the crop ΔL of the rolling top and bottom and the width of the four corners are By correcting the overhang ΔW, it is possible to make both the width overhang ΔW and the crop length ΔL' of the product 4 after finish rolling small, and to form a planar shape with high rectangularity. However, in this case, the problem is how to determine the etching conditions, that is, the timing of etching rolling and the amount of etching (width reduction amount), given the plate rolling conditions (slab dimensions, finished product dimensions, amount of reduction before tenter rolling, etc.). If this is decided, the point is whether the planar shape of the finished product after finish rolling can be made into the shape with the highest degree of rectangularity. In the past, etching conditions were determined based on the empirical intuition of workers, which did not necessarily result in the optimum amount of etching, which often resulted in a product shape with poor width accuracy and little etching rolling effect. It was. The present invention was developed in view of the above-mentioned circumstances, and provides a method for numerically determining the optimum etching conditions for predetermined thick plate rolling conditions. The purpose is to improve the yield of In order to find the above-mentioned optimal etching conditions, the present inventors numerically determined the shape of the final product when rolling a thick plate under given rolling conditions and arbitrarily determined etching conditions. If it can be predicted, compare this predicted final product shape with the desired final product shape, and if they do not match, modify the initial arbitrary etching conditions and re-predict to match the predicted final product shape with the desired final product shape. It was determined that the optimal etching conditions could be determined at the time when the above-mentioned predetermined rolling conditions and arbitrary etching conditions coincided with each other. The inventors first determined that the planar shape of the final product is the amount of width ΔW at the four corners that will be obtained in the final product.
Focusing on the fact that it is possible to make general evaluations such as drum-like shape or drum-like shape based on the top and bottom crop lengths ΔL, changes in the planar shape of the rolled material during the rolling process are calculated by the amount of width overhang. Considering the change in ΔW and crop length ΔL, we measured the actual rolled material and conducted a model rolling test using a miniature lead slab to determine the width overhang of the rolled material (hereinafter simply referred to as ΔW) and the crop length (hereinafter simply referred to as ΔL). We investigated in detail the deformation mode of (described below). As a result, the planar shapes ΔW and ΔL of the final product in thick plate rolling accompanied by this type of edge rolling are as shown in FIG. 5A.
Amount of change Δ in the planar shape of rolled material 2 when rolled at
The step of predicting W _A and ΔL _A and the step of estimating the rolled material 1' which is deformed into a dog bone shape when the rolled material 1 having a rectangular cross-sectional shape is etched and rolled with the edger rolls 5 and 5' as shown in FIG. The rolled material in step A is divided into two steps: a step of predicting ΔW ₁ and ΔL ₁ of the rolled material 3 after it has been flattened through horizontal rolling ( _HD pass) in which only the raised portion is rolled down (called "H D pass"). A formula for predicting ΔW _A and ΔL _A of the rolled material 3 and a formula for predicting ΔW and ΔL of the rolled material 3 in Step B are created, and the values obtained by the formula of Step A and the values obtained by the formula of Step B are rolled. It was confirmed that the final planar shape could be predicted with high accuracy by overlapping them according to the process. Here, etching is carried out with the roll gap of the vertical rolls set at a constant rolling width in step B. Further, the amount of reduction in the subsequent horizontal rolling (dock bone killing pass) is equal to the total value of the heights of the raised portions on the front and back surfaces generated in the etching rolling. In the case of step A in FIG. 5, the planar shape of the rolled material before horizontal rolling is rectangular (ΔW=ΔL=
0), but more generally the planar shape before rolling is not rectangular (ΔW≠0, ΔL≠0), so in this case, the changes in ΔW and ΔL before and after rolling ΔW _A ,
ΔL after horizontal rolling using the equation to predict ΔL _A
W and ΔL may be predicted. Figure 6 shows an example of a model rolling experiment using miniature lead slabs regarding the above predictions. and when rolled with a model horizontal mill with a work roll diameter of 105 mm. In case A, the slab is subjected to edge rolling (V pass), dog bone killing pass ( _HD pass), and then horizontal rolling (H pass). This figure shows the planar shape change in the direction with the original slab as a reference. On the other hand, case B is the case where the dogbone killing pass ( _HD pass) is omitted in the above case A.
The shape of the rolled material after H-double rolling is shown in the same way as above, and corresponds to normal rolling. Etching rolling (V-pass) is a two-pass round trip, with each pass 2
A width reduction of mm was performed, and the rolling reduction amount of the subsequent horizontal rolling (H pass) was 2 mm. There is a slight difference in the shape of the width change after both V and H rolling between Case A and Case B, but this degree of difference is due to the difference in the shape of double bulging on the sides. For example, case A and case B are approximately the same in terms of width deviations (corresponding to ΔW) at the leading and trailing ends with respect to the center in the longitudinal direction. In addition, the leading and trailing end crop lengths after both V and H rolling are approximately the same in case A and case B. Based on this experimental data, the shape of the rolled material after normal V・H is the same as the shape of the rolled material made flat after the dog bone killing pass (H _D pass), and the shape of the rolled material after the normal V・H
This shows that the amount of change in the shape of the rolled material during horizontal rolling (H pass) can be seen as overlapping, and from this fact, the amount of change in the planar shape of the rolled material during horizontal rolling (H pass) ΔW _A , ΔL _A The calculation formula of step A to predict and the planar shape of the rolled material before etching rolling (Δ
W ₀ , ΔL ₀ ) is used as a reference to predict the planar shape ΔW ₁ , ΔL ₁ of the rolled material after edge rolling (V pass) and dog bone killing pass ( _HD pass). It is possible to predict the planar shapes ΔW _F , ΔL _F of the finished product, and if the planar shapes ΔW _F , ΔL _F of the final product can be predicted, it is possible to predict the planar shape ΔW F , ΔL F of the final product. It can be said that the optimum etching conditions (reduction amount and timing) can be found from the formula for predicting step A and the formula for predicting step B. That is, the present invention provides a method for rolling a rectangular cross-section of a rolled material when horizontally rolling a rolled material in a thick plate rolling process in which vertical rolls perform etching rolling on the widthwise side surface and longitudinal side surface of the rolled material during the rolling process using horizontal rolls. The amount of change in width overhang ΔW _A and the amount of change in crop length ΔL _A are predicted by formulas, and on the other hand, the amount of width overhang of the rolled material when horizontal rolling is performed to flatten only the raised part during etching rolling. The numerical values of ΔW ₁ and crop length ΔL ₁ are predicted using formulas, and the former formula for predicting ΔW _A and ΔL _A and the latter formula for predicting ΔW ₁ and ΔL ₁ are combined to calculate the width overhang of the final product. Predict ΔW _F and crop length ΔL _F , and aim for the predicted values of ΔW _F and ΔL _F to determine the width overhang amount ΔW _C and crop length ΔL _C of the final product.
This is a thick plate rolling method that aims to find the optimum etching conditions such that Here, an example of a formula for predicting the numerical values of the amount of change ΔW _A in the amount of width overhang and the amount of change ΔL _A in crop length of the rolled material during horizontal rolling is shown below. Regarding the top side of the rolling pass ΔW _A (T)= ^6.1・r _T ^0.953・(h ₀ /R) ^{0.428 [} 1] ΔL _A (T)= ^2.23h ₀ /h・r _T ^0.74 ( W ₀ /R) ^0.352 [2] Regarding the bottom side of the rolling pass ΔW _A (B) = 8.22r _T ⁰ . ⁶⁸⁹・(h ₀ /R) ^{0. 471 [} 3] ΔL _A (B) = 9.02・h ₀ /h・r _T ^0.74 (h ₀ / ^{R) 0.262・(W 0 /R) 0.172 [} ₄ ^] However, r _T is the horizontal path output that ^is currently being calculated from the slab thickness h ₀ ^. The total reduction rate up to the side plank h, W ₀ is the slab width, R is the horizontal roll radius, all units are mm. Note that the above formulas [1] to [4] are all formulas corresponding to a 1/10 scale lead model rolled material. Next, the width overhang amount ΔW ₁ and crop length ΔL ₁ of the rolled material after the dog bone killing pass during etching rolling are calculated from the width overhang amount of the rolled material before etching rolling, which was calculated using formulas [1] to [4] above. An example of a formula for prediction based on ΔW ₀ and crop length ΔL ₀ and how to derive it is shown below. Note that ΔW ₁ and ΔL ₁ calculated below are both expressed as the average value of the top and bottom. First, a model rolling test using miniature lead slabs was conducted and a prediction formula for ΔW ₁ was derived. The conditions for the model rolling test are based on the assumption that the actual machine is 1/10 scale, and the dimensions of the lead miniature slab are 10 to 20 mm thick.
mm, width 150 to 320 mm, and length 150 to 190 mm. The mill is a model mill with a roll diameter of 100 mm, and the horizontal rolling mill used for the dog bone killing pass is a model horizontal mill with a work roll diameter of 105 mm. The procedure is first to edging the slab in two reciprocating passes with a width reduction of 1 to 3 mm per pass (V pass).
Thereafter, a dog bone killing pass ( _HD pass) was performed to measure the planar shape. In addition, the planar shape after the _VHD pass when the slab was turned 90 degrees in the horizontal plane was also measured in the same manner as above. Width overhang amount ΔW ₁ (M) in both cases
FIG. 7 shows the relationship between (average value of top and bottom ΔW) and the total rolling reduction amount (ΣΔV) in the V-rolling reciprocating pass. As shown in the figure, the width overhang amount ΔW ₁ (M) of the rolled material after the _VHD pass is the same as the width overhang amount ΔW ₀ (M) before the etching rolling (V pass).
It can be calculated using the formula below regardless of the top and bottom average values. ∆W ₁ (M) = -1.2 (Σ∆V) ^0.7 [5] Here, the width extension _amount after the V-HD pass, which is calculated from ^the width extension amount ΔW ₀ before the V- _HD pass and the above formula [5] Amount of change in ΔW from ΔW ₁ to _VHD pass δΔ
W is defined by the following formula. δΔW=ΔW ₁ −ΔW ₀ [6] Similarly, the amount of change in ΔL in the _VHD pass δΔ
L is defined by the following equation. δΔL=ΔL ₁ −ΔL ₀ [7] FIG. 8 shows a plot of the relationship between δΔW and δΔL based on the data of the model rolling. In the same figure, for example, if the shape of the rolled material before the V/ _HD pass is a rectangular shape indicated by ●, then δΔW and δ
The relationship between ΔL is approximately on a straight line. The slope of this straight line changes depending on the shape before the V/ _HD pass, but if the shape before the V/ _HD pass is other than a rectangle, for example, the shape of a drum as shown by 〓, □, △ or the shape of a drum as shown by ○. Regardless of the case, they all seem to lie approximately on a single straight line. From this fact, δΔW
The ratio of and δΔL is defined by the following formula as α. α=δΔW/δΔL [8] FIG. 9 is a plot of the relationship between α and the width extension amount ΔW ₀ before the _VHD pass, based on the data in FIG. 8. As shown in the figure, α is given by the following formula. α=0.3 ⁽ ΔW ₀ +5.35) ^0.482

[9] We have made some considerations regarding this point. That is, in Fig. 10, △bdc is defined as the unsteady deformation region during etching rolling (V pass),
Considering that △bdc is deformed to △bec after the V・H _D pass, the corner locus de caused by the V・H _D pass is one side bc of the unsteady deformation area △bdc defined earlier.
becomes parallel to Furthermore, since the ratio of the length and width of this unsteady deformation region changes depending on the amount of width extension ΔW ₀ before etching rolling, it can be said that the angle of the locus of de changes depending on ΔW ₀ . In any case, α is the formula

If found in [9], V.H.
The amount of change δΔL in ΔL in _{the D} pass is determined as follows using the amount of change δΔW in ΔW from equation [8]. δΔL=δΔW/α [8'] On the other hand, since the crop length ΔL ₀ before the _VHD pass has already been determined, the crop length ΔL ₁ after the _VHD pass can be determined as follows. I can do it. ΔL ₁ = ΔL ₀ + δΔL [7'] In this way, ΔW _A determined by the above formulas [1] [3]
The width overhang amount ΔW F of the final product can be predicted by polymerizing ΔW ₁ determined by the above formula [5] according to the rolling process, and the width overhang amount ΔW _F of the final product can be predicted. The crop length ΔL _F of the final product can be predicted by alternately polymerizing the obtained ΔL _A and the ΔL ₁ finally obtained by the above formula [7'] in accordance with the rolling process. In addition, when the amount of change in ΔW and the amount of change in ΔL are polymerized, if the rolled material is rotated by 90 degrees in the horizontal plane, that is, during tentering rolling and C-direction L-direction etching rolling, In consideration of this point, it is necessary to add the change in ΔL after the turn to ΔW before the turn. Next, the process up to finding the optimum etching conditions will be explained according to the flowchart of FIG. First, the rolling conditions (slab dimensions, finished product dimensions, reduction amount until the start of tentering rolling, horizontal roll radius, etc.) are read into the calculator, the etching conditions (timing of etching and reduction amount) are arbitrarily assumed, and the rolling conditions are calculated after the H pass. ΔW _A and ΔL _A , ΔW ₁ and Δ after V・_HD pass
Find L ₁ . Next, these values are superimposed according to the rolling process as described above, and the width overhang and crop lengths ΔW _F and ΔL _F in the final product shape are predicted. The obtained ΔW _F and ΔL _F are compared with the final product shapes ΔW _C and ΔL _C to determine whether they match or not. If they do not match, the initial etching conditions are corrected until they match. Repeat the prediction calculation of the final product shape. ΔW _F , ΔL _F and ΔW _C , ΔL _C
The etching conditions when the conditions match are the optimum etching conditions for the predetermined rolling conditions. When determining the etching conditions, make sure that the etching conditions do not exceed the maximum load and maximum torque allowed by the etching tool, and ensure that the width reduction is within a range that does not cause buckling of the rolled material. It is necessary to pay attention to this, and it is not necessarily possible to achieve the shape of the finished product as the shape of the carrier under all rolling conditions, but it is possible to obtain a product shape that is closest to the shape of the carrier. Next, examples will be described. For the example of lead model rolling assuming a scale of 1/10 of the actual machine dimensions, formulas [1] [2] [3] [4] for predicting ΔW _A and ΔL _A after the H pass and the V/H _D pass are used. Formulas for predicting the subsequent ΔW ₁ and ΔL ₁ [5] [6] [7]
[8]

Using [9] [8'] [7'], the optimum values of etching conditions were determined according to the flowchart of FIG. The dimensions of the lead miniature slab are 24.5mm thick, 210
mm width, 230mm length, finished product dimensions are 1.6mm thick, 252mm
The slab had a width of 2935 mm and a length of 2935 mm, and the reduction amount until the start of tentering rolling was 0, that is, the slab was immediately tentered rolled. The desired shape of the final product was a cropped shape with a slight fishtail shape, and a slight width overhang. In this case, the above-mentioned formula [1] to predict the shape of the final product is

[9] The optimal etching conditions found using [8'] [7'] are that the full width reduction amount (total width reduction amount of each pass) is 7.7 mm for C direction etching before tenter rolling, and the width reduction amount of each pass is 7.7 mm. In the later L direction edging, the full width reduction was 2.2 mm. Figure 12 shows the results of a model rolling test based on these values. The figure shows the changes in cropping amount ΔL and width overhang amount ΔW during the process from slab to final product, both divided by the rolling reduction ratio in the L and C directions. 7 in the figure shows the model rolling. This is the actual measured planar shape of the final product obtained through testing, and it has a slightly overhanging width and a slightly fishtail-like cropped shape as intended. On the other hand, 8 in the figure is the prediction formula [1] ~

[9]
[8′] This is the predicted planar shape of the final product calculated using [7′], and the predicted planar shape 8 and the above-mentioned measured planar shape 7 match well, including the shape deformation process during rolling. . From this, it can be said that the method of predicting the shape of the final product and the method of determining the optimum amount and timing of etching devised by the present inventors are appropriate. As explained above, the present invention uses a formula for predicting changes in the planar shape of a rolled material after horizontal rolling and a formula for predicting the planar shape of a rolled material after a dogbone killing pass during edging rolling. By making it possible to accurately predict the final product shape of a slab rolled under given rolling conditions and arbitrary etching conditions, it is now possible to know the optimal etching conditions necessary to obtain the desired final product shape. This has an excellent effect of dramatically improving the yield of thick plate rolling.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the outline of thick plate rolling, Figure 2 is a diagram explaining the cropping and width expansion that occur during slab longitudinal rolling before tentering rolling, and Figure 3 is a diagram showing the final result due to the difference in the tentering ratio. A diagram explaining the difference between the crop shape and width shape of a product, Figure 4 is a diagram showing an example of controlling the planar shape by etching rolling, and Figure 5 is a diagram showing the prediction of changes in the planar shape by thick plate rolling accompanied by etching rolling. Figure 6 is a diagram explaining the validity of the prediction method shown in Figure 5 using a lead model rolling, and Figure 7 is a diagram explaining the leading and trailing edge widths that occur in the V/ _HD pass. Figure 8 shows the relationship between δΔW and δΔL. Figure 9 shows the relationship between α and ΔW. FIG. 11 is a flowchart for determining the optimum edging conditions; FIG. 12 is a diagram illustrating an example of the method of the present invention using lead model rolling. 1: Slab, 2, 3: Rolled material, 4: Final product,
5, 5': Edge roller, 6, 6': Horizontal rolling roll, ΔW _A , ΔL _A : Amount of change in width overhang of rolled material during horizontal rolling (H pass), amount of change in crop length, ΔW ₀ , ΔL ₀ : Width overhang amount of rolled material before edge rolling (V pass)/dog bone killing pass ( _HD pass), same crop length, ΔW ₁ , ΔL ₁ :
Width overhang amount and crop length of rolled material after V/ _HD pass.

Claims (1)

[Claims] 1. Changes in the amount of width overhang of a rolled material when a rectangular cross-section rolled material is horizontally rolled in thick plate rolling in which vertical rolls perform edge rolling on the widthwise and longitudinal sides of the rolled material during the rolling process using horizontal rolls. The numerical values of the amount of change ΔW _A and the amount of change in crop length ΔL _A are predicted using formulas, and on the other hand, after the rolled material is etched and rolled, horizontal rolling is performed to flatten only the bulges caused by the etching rolling. The values of width overhang ΔW ₁ and crop length ΔL ₁ are predicted using formulas, and the former formula for predicting ΔW _A and ΔL _A and the latter formula for predicting ΔW ₁ and ΔL ₁ are combined to obtain the final product. The width overhang amount ΔW _F and crop length ΔL _F are predicted, and the optimum etching conditions are determined so that the predicted values of ΔW _F and ΔL _F become the width overhang amount ΔW _C and crop length ΔL _C of the final product. A thick plate rolling method characterized by rolling under etching conditions.