JP5521724B2 - Width reduction method for metal slabs - Google Patents

Description

  The present invention relates to a method for reducing the width of a metal slab.

  In hot rolling of metal plates including steel plates, a metal slab is cast by continuous casting, and the metal slab is hot-rolled to form a metal plate. The width of the metal slab to be subjected to hot rolling is determined according to the required width of the metal plate after rolling, and metal slabs having various widths from wide to narrow are required.

  The width of the metal slab cast by continuous casting can be made the same as the width of the metal slab subjected to hot rolling. For example, when continuously casting a narrow metal slab, it is continuous compared to continuous casting of a wide slab. Casting productivity will be impaired. Therefore, in continuous casting, a wide metal slab is uniformly cast, the metal slab is reduced in width as necessary for hot rolling, and after forming a narrow metal slab for hot rolling, hot rolling is performed. To be done. Thereby, it becomes possible to improve the productivity of continuous casting by always performing continuous casting of a wide slab regardless of the width of the metal slab used in hot rolling.

  In reducing the width of a metal slab (hereinafter also simply referred to as “slab”), the roll width is reduced by a reduction roll disposed on both sides of the slab in the width direction.

  When the width of the slab is reduced by roll width reduction, plastic deformation and elongation occur on both sides in the longitudinal direction of the slab, and both ends in the longitudinal direction become a fishtail shape or a tongue shape, and this portion needs to be cut and removed as a crop. This is a factor that reduces the yield of products.

  Prior to roll width reduction, both ends in the longitudinal direction of the slab are preliminarily reduced using a press die, and then roll width reduction is performed, compared to width reduction only by roll width reduction. The fishtail shape or the tongue shape at both ends in the longitudinal direction can be reduced. For example, Patent Document 1 discloses a width reduction method in which the slab width is reduced to a predetermined width by roll width reduction over the entire length of the slab after the slab is pressed into a tapered shape at the front end portion and the rear end portion. . For press molding of a slab, press dies disposed on both sides in the width direction of the slab are used. The press mold is formed as a pair of molds having a pressing portion parallel to both side surfaces of the slab and an inclined portion provided to be connected to the pressing portion.

  Patent Document 2 describes an invention in which the width reduction amount of the slab is increased without excessively increasing the press load by performing a plurality of mold width reductions.

  In the roll width reduction, the larger the width reduction amount per roll reduction, the greater the reduction load under the width reduction. Further, the rolling load varies depending on the thickness of the slab and the temperature and component of the slab. In the roll width reduction device, since the allowable maximum value of the rolling load based on the equipment restrictions is determined, it is necessary to determine the width reduction amount per time so that the rolling load does not exceed the allowable maximum value. On the other hand, when rolling a wide slab after continuous casting into a narrow slab for hot rolling, productivity decreases as the number of roll width reductions decreases, so that the reduction load does not exceed the allowable maximum value. It is required to increase the roll width reduction amount per time as much as possible.

JP 2000-79401 A JP 2008-254034 A

  When determining the roll width reduction amount per width reduction prior to roll width reduction, the relationship between the roll width reduction amount and the reduction load is predicted in consideration of the shape, temperature, and components of the slab. The roll width reduction amount is determined so as not to exceed the maximum allowable value of the reduction load. Here, the predicted reduction load value and the actual reduction load value do not always coincide with each other, and both have variations. Therefore, in order to set the actual rolling load value so that it does not exceed the allowable maximum value, the predicted rolling load value is a certain amount smaller than the maximum allowable value after taking into account the variation between the actual value and the predicted value. Thus, the roll width reduction amount is determined. For example, the ratio of the actual reduction load value and the predicted reduction load value is calculated, and the standard deviation of the variation in this ratio is calculated. The estimated reduction load value is smaller than the allowable maximum value by 2.5 times the standard deviation. The roll reduction condition is determined so as to be a value.

  Conventionally, the variation between the actual rolling load reduction value and the predicted rolling load value is large, and the maximum allowable rolling load value is 14MN (Mega Newton). The roll reduction condition was determined to be 12 MN or less, and as a result, the maximum value of the actual reduction load value was about 12 MN on average, and the equipment capacity of the roll width reduction device could not be fully utilized.

  In the present invention, the prediction accuracy of the roll width reduction load is improved, the variation between the actual rolling load reduction value and the predicted reduction load value is reduced, and the roll width reduction condition as close as possible to the equipment allowable capacity is adopted. It is an object of the present invention to provide a method for reducing the width of a metal slab that can be reduced in width.

That is, the gist of the present invention is as follows .
(1) About the longitudinal direction both ends or one edge part of the metal slab 10, a mold width reduction is performed by the press metal mold | die 5 arrange | positioned at the width direction both sides, and then by the roll 7 for reduction arranged at the width direction both sides In the width reduction method of the metal slab that performs roll width reduction,
The deformation resistance prediction value Km of the metal slab at the time of width reduction is determined in advance, and the reduction load prediction value Pc ₁ of the mold width reduction is determined based on the deformation resistance prediction value Km.
Measure the actual load value Pr ₁ when the mold width is reduced and the actual load value Pr ₂ when the roll width is reduced.
The ratio of the actual reduction load value Pr ₁ and the predicted reduction load value Pc ₁ when the mold width is reduced (hereinafter referred to as “the actual reduction impression ratio Rrc ₁ ”) is calculated.
Using the predetermined deformation resistance prediction value Km and the mold reduction load actual result prediction ratio Rrc ₁ , the reduction load prediction value Pc ₂ under the roll width reduction is corrected,
Based on the results of width reduction of a plurality of metal slabs, the ratio between the rolling load actual value Pr ₂ under roll width reduction and the rolling load predicted value Pc ₂ under roll width reduction (hereinafter referred to as “roll rolling load actual result prediction ratio Rrc ₂ ”). The maximum allowable value Pc ₂ max of the rolling load predicted value under the roll width reduction is determined according to the magnitude of the variation of the roll rolling load actual performance prediction ratio Rrc ₂ , and the rolling load predicted value under the roll width reduction is determined. width reduction method of the metal slab Pc _2, characterized in that the determining the roll width reduction conditions so as not to exceed the maximum allowable value Pc ₂ max.
( 2 ) The metal slab 10 is subjected to mold width reduction by pressing dies 5 arranged on both sides in the width direction at both longitudinal ends or one end of the metal slab 10, and then by a rolling roll 7 arranged on both sides in the width direction. In the width reduction method of the metal slab that performs roll width reduction,
Measure the actual load value Pr ₁ when the mold width is reduced and the actual load value Pr ₂ when the roll width is reduced.
Calculate the actual deformation resistance value of the metal slab at the time of width reduction from the actual rolling load value Pr ₁ at the time of mold width reduction.
Using the actual deformation resistance value , the rolling load predicted value Pc ₂ under the roll width reduction is corrected,
Based on the results of width reduction of a plurality of metal slabs, the ratio between the rolling load actual value Pr ₂ under roll width reduction and the rolling load predicted value Pc ₂ under roll width reduction (hereinafter referred to as “roll rolling load actual result prediction ratio Rrc ₂ ”). The maximum allowable value Pc ₂ max of the rolling load predicted value under the roll width reduction is determined according to the magnitude of the variation of the roll rolling load actual performance prediction ratio Rrc ₂ , and the rolling load predicted value under the roll width reduction is determined. width reduction method of the metal slab Pc _2, characterized in that the determining the roll width reduction conditions so as not to exceed the maximum allowable value Pc ₂ max.

  The present invention measures the actual load reduction value under the mold width reduction performed prior to the roll width reduction of the metal slab, and the roll width reduction condition and the predicted reduction load value under the roll width reduction based on the actual reduction load value. Therefore, the prediction accuracy is improved, and it is possible to reduce the width by adopting the roll width reduction condition as close as possible to the equipment allowable capacity.

It is the whole slab width reduction apparatus schematic, (a) is a top view, (b) is a side view. It is a fragmentary sectional view showing change of mold width reduction. It is a figure which shows the calculation method of the contact projection length at the time of width reduction, (a) (b) is a case where die width reduction is performed, (c) is the case of roll width reduction. It is a figure which shows the relationship between the rolling load prediction value in the roll width reduction of this invention, and a rolling load actual value. It is a figure which shows the relationship between the rolling-down load predicted value in the conventional roll width reduction, and a rolling-down load actual value.

  FIG. 1 is a conceptual diagram showing the entire slab width reduction. The metal slab 10 exiting the continuous casting machine 1 is charged into the heating furnace 2 and heated to make the temperature uniform. Next, the metal slab 10 carried out from the heating furnace 2 is guided to the mold width reduction device 3. In the mold width reduction device 3, press dies 5 are arranged on both sides in the width direction of the slab. The press mold 5 is formed as a pair of molds having a pressing portion 11 parallel to both side surfaces of the slab and an inclined portion 12 provided to be connected to the pressing portion 11. As shown in FIG. 2, both ends in the longitudinal direction of the slab are pressed from the width direction with the press dies 5 arranged on both sides of the slab width direction. 2 (a), the slab is moved a plurality of times in the width direction as necessary as shown in FIGS. 2 (b) and 2 (c), and then in the longitudinal direction as shown in FIG. 2 (d). (E) By performing width reduction several times like (f), the shape of the longitudinal direction both ends of a slab can be made into a tapered shape (FIG.2 (g)).

  Next, as shown in FIG. 1, the slab 10 is guided to the roll width reduction device 4. In the roll width reduction device 4, the reduction rolls 7 are arranged on both sides in the width direction of the slab, the reduction rolls 7 are arranged at roll intervals corresponding to the width reduction amount, and the slab 10 is fed between the reduction rolls 7. As a result, the roll width is reduced.

  In both the mold width reduction and the roll width reduction, the reduction load is determined by the slab shape, the reduction condition, and the deformation resistance of the slab. The deformation resistance of the slab is affected by the slab temperature and the slab component.

  First, the reduction load under the roll width reduction will be described.

The predicted deformation resistance value of the slab is Km. Km is a coefficient determined by the temperature and components of the slab. The rolling load predicted value Pc ₂ under the roll width reduction is the deformation resistance predicted value Km, the slab thickness H ₂ during the roll width reduction, the contact projection length L _{2 during} the roll width reduction, and the rolling force function Q ₂ during the roll width reduction. From the above, it is calculated by the following formula. The contact projection length L ₂ when the roll width is reduced can be calculated based on FIG.
Pc ₂ = Km × H ₂ × L ₂ × Q ₂ (1)

The rolling force function Q ₂ when the roll width is reduced is, for example, Q ₂ = 0.8 × (0.45 × r + 0.04) · [(R / W ₂ ) ^0.5 −0.5] (2)
As required. Here, W ₂ is the slab width before reduction, r is the width reduction rate (= ΔE / W ₂ ), ΔE is the width reduction amount (= W ₂ −E), and R = ΔE / 4 + L ₂ ² / ΔE.

The maximum value Pc ₂ max of the predicted rolling load under the roll width is determined in advance. In the roll width reduction device 4, an allowable maximum value Prmax of the reduction load is determined based on equipment constraints. The maximum value Pc ₂ max of the rolling reduction predicted value is determined as a value lower than the allowable maximum value Prmax of the rolling load. This is because even if the actual rolling reduction value Pr ₂ is higher than the predicted rolling load value Pc ₂ , it does not exceed the allowable maximum value Prmax of the rolling load. As the difference variation between the predicted value of the rolling load and the actual value is larger, the safety factor needs to be increased. Therefore, it is necessary to set the maximum value Pc ₂ max of the rolling load predicted value to a smaller value.

When the roll width is reduced, the surface temperature of the slab to be subjected to the width reduction is measured, and the predicted deformation resistance value Km is determined using the measured slab temperature and the predicted value or actual value of the slab component. Then, after preliminarily determining the roll width reduction condition, the reduction load predicted value Pc ₂ is calculated by the above equation (1). Then, the pressure load prediction value Pc ₂ so as not to exceed the maximum value Pc ₂ max of the rolling load prediction value, and finally to determine the roll width reduction conditions. It is also possible to determine the roll width reduction condition by setting the reduction load predicted value Pc ₂ equal to the maximum value Pc ₂ max of the reduction load prediction value and calculating the equation (1) in reverse.

The roll width reduction device 4 is provided with a roll width reduction load measuring device 22, whereby the actual measurement value Pr _{2 of the} reduction load can be measured. Then, the rolling load predicted value Pc ₂ calculated using the equation (1) is compared with the rolling load actual measurement value Pr ₂ , for example, the ratio between them (the roll rolling load actual load forecast ratio Rrc ₂ ).
Rrc ₂ = Pr ₂ / Pc ₂ (3)
Is calculated, and the variation standard deviation σ of Rrc ₂ is obtained based on the roll reduction results of a large number of slabs. As described above, the greater the variation in the difference between the predicted value of the rolling load and the actual value (the larger the σ), the larger the safety factor needs to be. Therefore, the maximum value Pc ₂ max of the rolling load predicted value is It is determined as a lower value than the maximum allowable load value Prmax. For example,
Pc ₂ max = (1−2.5 × σ) × Prmax (4)
And As a result, even if the actual rolling load value Pr ₂ significantly exceeds the predicted rolling load value Pc ₂ , it is possible to avoid the risk that the actual rolling load value Pr ₂ will exceed the allowable maximum value Prmax of the rolling load. .

When the variation standard deviation σ of Rrc ₂ in equation (3) was determined under the actual roll width pressure, a result of σ = 0.06 was obtained. Further, the allowable maximum value Prmax = 14MN of the rolling load of the roll width rolling device. Therefore, the maximum value Pc ₂ max of the predicted rolling load is obtained by the equation (4).
Pc ₂ max = (1−2.5 × σ) × Prmax
= (1-2.5 × 0.06) × 14≈12 (MN)

Therefore, when determining the roll reduction condition in each slab, the roll reduction condition was determined using the equation (1) so that the predicted reduction load Pc ₂ does not exceed 12 MN. FIG. 5 shows the relationship between the predicted reduction load value Pc ₂ and the actual reduction load value Pr ₂ . As is apparent from FIG. 5, as a result of determining the roll reduction condition so that it does not exceed 12 MN even if the predicted reduction load Pc ₂ is large, the actual reduction load value could be kept below 14 MN.

  Next, the rolling load under the mold width will be described.

Similar to the roll width reduction, for the mold width reduction, rolling load prediction value Pc ₁ of the mold width reduction can be defined as a function of the deformation resistance predicted value Km of the slab. Specifically, it is calculated by the following formula from the slab thickness H ₁ when the mold width is reduced, the contact projection length L ₁ when the mold width is reduced, and the reduction force function Q ₁ when the mold width is reduced.
Pc ₁ = Km × H ₁ × L ₁ × Q ₁ (5)
The contact projection length L ₁ when the mold width is reduced can be determined as L ₁ shown in FIGS. The reduction force function Q ₁ at the time of mold width reduction is, for example, Q ₁ = (π + W ₁ / L ₁ ) / 4 (6)
As required. Here, W ₁ is the slab thickness before rolling.

In the present invention, the actual rolling load value Pr ₁ at the time of mold width reduction is measured. For example, Pr ₁ can be measured by providing a mold width reduction load measuring device 21 using a load cell in the mold width reduction device. Indeed the slab performing width reduction, since the reduction load prediction value Pc ₁ and rolling load actual value Pr ₁ in the mold width reduction can be contrasted, based on the comparison result, modifying the deformation resistance predicted value Km of the slab It becomes possible to do. Alternatively, instead of correcting the deformation resistance prediction value Km of the slab, the roll load reduction condition and the roll load reduction reduction predicted load value Pc ₂ in relation to the roll width reduction are expressed in terms of the rolling load results when the die width is reduced. it is also possible to modify directly based on the value Pr _1. If the roll width reduction condition is determined after making such corrections, it is possible to reduce the variation between the roll load predicted value Pc ₂ and roll actual load value Pr ₂ under the roll width reduction as compared to the conventional case. become.

That is, the relationship between the roll width reduction condition and the roll load reduction predicted value Pc ₂ is determined based on the actual reduction load value Pr ₁ when the mold width is reduced, and the roll width reduction condition and the roll load under the roll width reduction are determined. based on the relationship between the predicted value Pc _2, by determining the roll width reduction conditions, since the variation of pressure load estimated value Pc ₂ and pressure load actual value Pr ₂ of the roll width reduction is reduced, reduction of roll width reduction The maximum value Pc ₂ max of the predicted load value can be set to a larger value (a value close to the allowable maximum value Prmax of the roll load reduction device), and the roll width that fully utilizes the equipment capability of the roll width reduction device It is possible to perform the reduction.

  Hereinafter, a specific description will be given based on the first and second embodiments of the present invention.

  A first embodiment of the present invention will be described.

In the first embodiment, first, a deformation resistance prediction value Km of the metal slab at the time of width reduction is determined in advance. The deformation resistance prediction value Km is determined in advance as a function to be calculated based on the slab surface temperature, the slab component, etc. during width reduction. Next, a reduction load prediction value Pc ₁ under the mold width reduction is determined based on the deformation resistance prediction value Km. For example, Pc ₁ can be calculated by the equation (5). In the present invention as described above, to measure the rolling load actual value Pr ₁ when the mold width reduction. Using this Pr ₁ , the ratio of the actual rolling load actual value Pr ₁ at the time of mold width reduction and the calculated actual rolling load predicted value Pc ₁ (the actual mold pressing load actual ratio Rrc ₁ ) is calculated.
Rrc ₁ = Pr ₁ / Pc ₁ (7)

By using this mold pressure load actual prediction ratio Rrc _1, it is possible to correct the deformation resistance predicted value Km of the slab to a more accurate value. For example,
Km '= Rrc ₁ x Km
As can be corrected. In the actual calculation, Km itself is not corrected, but the roll width reduction condition and the roll load reduction predicted value Pc ₂ based on the predetermined deformation resistance prediction value Km and the die reduction load actual result prediction ratio Rrc _1. To establish a relationship with Specifically, the equation (1) is corrected,
Pc ₂ = Rrc ₁ × Km × H ₂ × L ₂ × Q ₂ (8)
As a result, a rolling load predicted value Pc ₂ under the roll width is calculated. In this way, as a result of correcting the rolling load predicted value Pc ₂ under the roll width reduction using Rrc ₁ obtained from the results of the mold width reduction, the predicted rolling load predicted value under the roll width reduction is obtained with higher accuracy than before. Is possible.

  Next, a second embodiment of the present invention will be described.

In the second embodiment, the actual deformation resistance value Km _r of the metal slab at the time of width reduction is calculated from the actual reduction load value Pr ₁ at the time of mold width reduction. That is, the equation (5) Pc ₁ = Km × H ₁ × L ₁ × Q ₁ (5)
In this case, Km _r can be obtained by substituting Pc ₁ with Pr ₁ and calculating backward from this equation.
Km _r = Pr ₁ / (H ₁ × L ₁ × Q ₁ ) (9)

Based on the actual deformation resistance value Km _r thus determined, the relationship between the roll width reduction condition and the roll load predicted value Pc ₂ under the roll width reduction is determined. Specifically, the (1) equation (1) below the Km was replaced Km _r 'of formula can be obtained reduction load prediction value Pc ₂ of the roll width reduction using.
Pc ₂ = Km _r × H ₂ × L ₂ × Q ₂ (1) ′

In this way, as a result of calculating the actual deformation resistance value Km _r of the metal slab at the time of width reduction for the slab from the actual reduction load value Pr ₁ at the time of mold width reduction, the reduction of the roll width reduction with higher accuracy than before is achieved. It is possible to obtain a predicted load value.

  In the first embodiment and the second embodiment, the calculation order is merely changed, and both are based on substantially the same principle.

  The present invention that performs roll width reduction by making full use of the capability of the roll width reduction device after determining the predicted reduction load under roll width reduction with higher accuracy than before will be described.

Applying the present invention to measure the pressure load actual value Pr ₁ when the mold width reduction, based on the rolling load actual value Pr ₁ when the mold width reduction, rolling the roll width reduction conditions and roll width reduction defines the relationship between the load prediction value Pc _2, based on the relationship between the rolling load prediction value Pc ₂ of the roll width reduction conditions and the roll width reduction, it defines the roll width reduction conditions. At this time, the actual measurement value Pr ₂ of the rolling load when the roll width is reduced is measured. Then, from the results of the width reduction of the plurality of metal slabs, variation in the ratio (roll roll load actual result prediction ratio Rrc ₂ ) between the roll load actual reduction value Pr ₂ and the roll load predicted value Pc ₂ under the roll width reduction, for example, the standard deviation σ Is calculated.
Rrc ₂ = Pr ₂ / Pc ₂ (3)

Further, a maximum allowable value Pc ₂ max of the rolling load predicted value under the roll width reduction is determined according to the variation of the roll rolling load actual result prediction ratio Rrc ₂ , and the rolling load predicted value under the roll width reduction is the maximum allowable value. The roll width reduction condition is determined so as to be less than the value. Here, when determining the maximum allowable value Pc ₂ max of the rolling load predicted value under the roll width reduction, even if the actual rolling load value Pr ₂ is higher than the predicted rolling load value Pc ₂ , the allowable maximum value Prmax of the rolling load It is determined not to exceed. Specifically, the relationship between the maximum value Pc ₂ max of the rolling reduction predicted value and the allowable maximum value Prmax of the rolling load is determined as a function of the standard deviation σ of the roll rolling load actual result prediction ratio Rrc ₂ . More specifically, for example, the ratio (Pc ₂ max / Prmax) of the maximum value Pc ₂ max of the predicted rolling load and the allowable maximum value Prmax of the rolling load is equal to or smaller than (1−2.5σ). Determine to be. If the safety factor is set to be larger than 2.5σ, the frequency at which the actual rolling load value Pr ₂ exceeds the allowable maximum value Prmax of the rolling load is practically harmless. As for the safety factor, in addition to 2.5σ, it may be set to 3.0σ for further safety. Further, when it is important to improve the productivity under the roll width reduction, 2.0σ can be set.

  As shown in FIG. 1, the steel slab cast by the continuous casting machine 1 is targeted, and the mold width is reduced by pressing dies 5 arranged on both sides in the width direction at both ends in the longitudinal direction, and then on both sides in the width direction. The present invention was applied when performing roll width reduction by the arranged roll 7 for reduction. The shape of the steel slab 10 immediately after continuous casting is 280 mm in thickness and 1800 mm in width. The slab width after width reduction is 750 to 1800 mm.

The steel slab after continuous casting is charged into the heating furnace 2 and heated so that the surface temperature of the slab becomes about 1100 ° C. Next, the metal slab carried out from the heating furnace 2 is guided to the mold width reduction device 3. In the mold width reduction device 3, press dies 5 are disposed on both sides of the slab 10 in the width direction. The press die 5 includes a pressing portion 11 parallel to both side surfaces of the slab, and an inclined portion 12 provided so as to be connected to the pressing portion 11. The press dies 5 arranged on both sides in the slab width direction are pressed against the slab by the press device 6 and press both ends in the longitudinal direction of the slab from the width direction. The pressing device 6 is provided with a die width reduction load measuring device 21 and can measure the actual reduction load value Pr ₁ when the die is reduced. Further, based on the width reduction pattern, a contact projection length L ₁ at the time of mold width reduction is determined as shown in FIGS. As a result of the mold width reduction, the steel slab has a tapered shape at both ends in the longitudinal direction of the slab as shown in FIG.

Next, the slab is guided to the roll width reduction device 4. In the roll width reduction device 4, the reduction rolls 7 are arranged on both sides in the width direction of the slab, the reduction rolls 7 are arranged at roll intervals corresponding to the width reduction amount, and the slab 10 is fed between the reduction rolls 7. As a result, the roll width is reduced. The diameter of the rolling roll 7 is 1000 mm, and the allowable maximum value Prmax of the rolling load is 14MN. A roll width reduction load measuring device 22 is provided on the support device of the reduction roll 7, and the actual reduction load value Pr ₂ under the roll width reduction can be measured.

In roll width reduction is determined pressure load actual value Pr ₂ when the roll width reduction width reduction pattern so as not to exceed 14MN an allowable maximum value Prmax the pressure load, i.e. the maximum width reduction quantity per time To do. When the roll width reduction allowance is less than the maximum width reduction amount per time, the roll width reduction can be performed once. When the roll width reduction allowance is larger than the maximum width reduction amount per time, the roll width reduction is performed in two or more times.

As the deformation resistance prediction value Km, a function Km represented by the following equation (10) called “Misaka equation” was used. Here, for T to be substituted into equation (10), the temperature distribution in the slab is calculated by calculating the temperature rise state in the heating furnace for each slab based on the ambient temperature and the temperature rise time results. The absolute temperature of the slab cross section average was calculated from the calculated temperature distribution in the slab.
Km = exp (K '+ A / T) ・ ε ^0.21・ ε _dot ^0.13 [kgf / mm ² ] （10）
K ′ = 0.126−1.75C + 0.594C ²
A = 2851 + 2968C-1120C ²
Where, T: absolute temperature of slab cross section average (K)
C: Carbon equivalent (-)
ε: Strain (-)
ε _dot : strain rate (− / sec).

(Comparative example)
The width reduction was performed without applying the present invention.

In roll width reduction obtains the deformation resistance estimated value Km by the above equation (10), was calculated rolling load prediction value Pc ₂ based on the equation (1). The contact projection length L ₂ when the roll width is reduced is determined as shown in FIG. 3C, and the above formula (2) is adopted as the reduction force function Q ₂ when the roll width is reduced.

In the roll width reduction, the actual measurement value Pr _{2 of the} reduction load is measured and compared with the calculated reduction load predicted value Pc ₂ described above, and the roll reduction load actual result prediction ratio Rrc ₂ of the equation (3) is obtained. Based on the slab roll reduction result, the variation standard deviation σ of Rrc ₂ was determined. As a result, σ = 0.06. Therefore, when the safety factor was 2.5σ and the maximum value Pc ₂ max of the predicted rolling load was obtained by the above equation (4), Pc ₂ max = 12MN was obtained.

Therefore, when determining the roll reduction condition in each slab, the roll reduction condition was determined using the equation (1) so that the predicted reduction load Pc ₂ does not exceed 12 MN. FIG. 5 shows the relationship between the predicted reduction load value and the actual reduction load value. As is apparent from FIG. 5, as a result of determining the roll reduction condition so that it does not exceed 12 MN even if the predicted reduction load Pc ₂ is large, the actual reduction load value could be kept below 14 MN. However, since the maximum value of the rolling load predicted value Pc ₂ is suppressed to 12 MN, the ability of the roll width rolling down device cannot be utilized to the maximum.

(Invention Example 1)
In the present invention Example 1, above (10) defines a deformation resistance predicted value Km based on equation calculates a rolling load prediction value Pc ₁ during mold pressure by the based on the deformation resistance estimated value Km (5) formula did. The contact projection length L ₁ when the mold width is reduced is determined as L ₁ shown in FIGS. 3A and 3B, and the expression (6) is used as the reduction force function Q ₁ when the mold width is reduced. It was also measured rolling load actual value Pr ₁ when the mold pressure in a mold width rolling load measurement device 21 provided to the press device 6 of the mold width reduction device 3. Using these results, the ratio of the actual rolling load actual value Pr ₁ at the time of mold width reduction and the calculated actual rolling load predicted value Pc ₁ (the actual mold pressing load actual predicted ratio Rrc ₁ ) was calculated by the equation (7). .

Roll width reduction is continued for slabs for which mold width reduction has been completed. At this time, a predicted rolling load predicted value Pc ₂ under the roll width reduction was calculated using the equation (8) obtained by correcting the equation (1) with Rrc ₁ . The contact projection length L ₂ when the roll width is reduced is determined as shown in FIG. 3C, and the above formula (2) is adopted as the reduction force function Q ₂ when the roll width is reduced. Similarly the comparative example, the roll width reduction measures the pressure load measured value Pr _2, compared with the rolling load prediction value Pc ₂ calculated above, the equation (3) the roll reduction force actual prediction ratio Rrc ₂ Determination of In addition, based on the roll reduction results of a number of slabs, the variation standard deviation σ of Rrc ₂ was obtained. As a result, σ = 0.04. Therefore, when the safety factor is 2.5σ and the maximum value Pc ₂ max of the predicted rolling load is obtained by the above equation (4), Pc ₂ max = 13MN.

Therefore, when determining the roll reduction condition in each slab, the roll reduction condition was determined using equation (8) so that the predicted reduction load value Pc ₂ does not exceed 13 MN. FIG. 4 shows the relationship between the predicted reduction load value and the actual reduction load value. As is apparent from FIG. 4, as a result of determining the roll reduction condition so that the estimated rolling load predicted value Pc ₂ is large and does not exceed 13 MN, the actual rolling load value Pr ₂ could be kept below 14 MN. And since the maximum value of the rolling load predicted value Pc ₂ increased to 13 MN in the invention example 1 with respect to 12 MN of the comparative example, the capability of the roll width rolling down apparatus could be utilized to the maximum.

(Invention Example 2)
In Example 2 of the present invention, the actual reduction value Pr ₁ at the time of mold reduction is measured by using the mold width reduction load measuring device 21 provided in the press machine of the mold width reduction apparatus, and the above equation (9) Was used to calculate the actual deformation resistance value Km _r of the metal slab. The contact projection length L ₁ when the mold width is reduced is determined as L ₁ shown in FIGS. 3A and 3B, and the expression (6) is used as the reduction force function Q ₁ when the mold width is reduced.

Roll width reduction is continued for slabs for which mold width reduction has been completed. When calculating the rolling load predicted value Pc ₂ under the roll width reduction using the equation (1) ′, the value calculated by the equation (9) was used as the actual deformation resistance value Km _r . The contact projection length L ₂ when the roll width is reduced is determined as shown in FIG. 3C, and the above formula (2) is adopted as the reduction force function Q ₂ when the roll width is reduced. When the variation standard deviation σ of Rrc ₂ was determined in the same manner as in the first invention example, σ = 0.04, which was the same result as in the first invention example. Therefore, as in Example 1 of the present invention, when determining the roll reduction condition in each slab, the roll reduction condition was determined using the expression (1) ′ so that the predicted reduction load Pc ₂ does not exceed 13 MN even at most. . Suitable results similar to those of Example 1 of the present invention could be obtained.

DESCRIPTION OF SYMBOLS 1 Continuous casting machine 2 Heating furnace 3 Mold width reduction apparatus 4 Roll width reduction apparatus 5 Press die 6 Press apparatus 7 Roll for reduction 8 Slab conveyance apparatus 10 Slab 11 Press part 12 Inclination part 13 Slab side face 14 Slab longitudinal direction end surface 17 Tip 21 Mold width reduction load measuring device 22 Roll width reduction load measurement device Km Slab deformation resistance predicted value Km _r Slab deformation resistance actual value Pc ₁ Mold width reduction reduction predicted value Pr ₁ Mold width reduction Actual rolling reduction value Pc ₂ Actual rolling load reduction value under roll width Pr ₂ Actual rolling load reduction value under roll width Prmax Maximum allowable rolling load Rrc ₁ Die rolling actual load prediction ratio Rrc ₂ Actual roll rolling load prediction ratio Pc ₂ max Maximum value of predicted rolling load

Claims (2)

Metal that performs metal width reduction by pressing dies arranged on both sides in the width direction, and then roll width reduction by rolling rolls arranged on both sides in the width direction at both ends or one end of the metal slab In the slab width reduction method,
Predetermined deformation resistance prediction value of the metal slab at the time of width reduction, based on the deformation resistance prediction value to determine the reduction load prediction value of the mold width reduction,
Measure the actual load value when the die width is reduced and the actual load value when the roll width is reduced.
A ratio of the actual rolling load actual value and the predicted actual rolling load at the time of the mold width reduction (hereinafter referred to as “the actual mold pressing load actual prediction ratio”) is calculated,
Correcting the rolling load prediction value of the roll width reduction with deformation resistance predicted value and the die pressure load results predicted ratio defined above,
From the results of the width reduction of a plurality of metal slabs, the variation of the ratio of the actual rolling load reduction value of the roll width reduction and the predicted reduction load value of the roll width reduction (hereinafter referred to as the “roll reduction load actual result prediction ratio”) is calculated.
The maximum allowable value of the rolling load predicted value under the roll width reduction is determined according to the size of the variation in the roll rolling load actual prediction ratio, and the roll load is predicted so that the predicted rolling load under the roll width is less than the maximum allowable value. A method for reducing the width of a metal slab, characterized by defining a width reduction condition . Metal that performs metal width reduction by pressing dies arranged on both sides in the width direction, and then roll width reduction by rolling rolls arranged on both sides in the width direction at both ends or one end of the metal slab In the slab width reduction method,
Measure the actual load value when the die width is reduced and the actual load value when the roll width is reduced.
Calculate the deformation resistance actual value of the metal slab during the width reduction from the actual rolling load actual value during the mold width reduction,
Using the actual deformation resistance value , correct the rolling load predicted value under the roll width reduction ,
From the results of the width reduction of a plurality of metal slabs, the variation of the ratio of the actual rolling load reduction value of the roll width reduction and the predicted reduction load value of the roll width reduction (hereinafter referred to as the “roll reduction load actual result prediction ratio”) is calculated.
The maximum allowable value of the rolling load predicted value under the roll width reduction is determined according to the size of the variation in the roll rolling load actual prediction ratio, and the roll load is predicted so that the predicted rolling load under the roll width is less than the maximum allowable value. A method for reducing the width of a metal slab, characterized by defining a width reduction condition .

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