JP5849937B2 - Slab cutting method and slab cutting device in continuous casting machine - Google Patents

Description

  The present invention relates to a slab cutting method and a slab cutting apparatus in a continuous casting machine that cuts a slab with a specified weight.

  In general, in a continuous casting facility, molten steel poured into a mold is solidified by cooling from the surroundings to form a shell. The molten steel in which the shell is formed is drawn vertically downward from directly under the mold, and is corrected in the horizontal direction while being cooled by water-cooled spray to form a flat strand. The strand is cut downstream into a slab of a predetermined length.

  Conventionally, the cutting length of a slab is calculated from a nominal unit weight and a correction coefficient for correcting the nominal unit weight in accordance with a designated weight. Here, the nominal unit weight means the weight per unit length of the strand determined using the cross-sectional area of the mold and the specific gravity determined by the molten steel components. The cross-sectional area of the strand can be regarded as the same as the cross-sectional area of the mold immediately after being drawn out of the mold, but changes after being cooled. For this reason, the nominal unit weight is corrected to the weight per unit length of the strand just before cutting using a correction coefficient (hot correction coefficient), and the cutting length corresponding to the specified weight is calculated to cut the slab. doing.

  The correction coefficient is calculated based on the measured values of casting conditions such as the amount of cooling water with respect to the casting amount per unit time and the time from when the strand is pulled out of the mold until it reaches the torch cutter that cuts the strand (casting time). ing. Further, Patent Document 1 discloses a hot process based on the time required for passage of a strand in a continuous casting machine reflecting the degree of cooling of the strand (residence time in the machine) so as to correspond to a case where casting conditions change during casting. A technique for further correcting the cutting length corrected by the correction coefficient is described.

JP 2012-24817 A

  By the way, in the continuous casting machine, in order to prevent the occurrence of a situation in which the weight of the slab is insufficient in the next process, weight compensation for cutting the slab by adding a predetermined weight (additional weight) to the specified weight is performed. ing. Specifically, weight compensation is performed by converting the added weight into a length and adding it to the cutting length.

  However, since the width of the slab that reaches the torch cutter is not constant and varies, when the weight compensation is performed by converting the additional weight into a length, the additional weight may be excessive or insufficient. If the added weight is excessive or insufficient, the yield rate of the slab will decrease.

  The present invention has been made in view of the above, and an object of the present invention is to provide a slab cutting method and a slab cutting apparatus in a continuous casting machine capable of cutting a slab with high precision and a specified weight.

  In order to solve the above-described problems and achieve the object, a slab cutting method in a continuous casting machine according to the present invention includes a slab having a specified length of a strand drawn from a mold in the continuous casting machine. A method for cutting a slab in a continuous casting machine that cuts into a continuous length, which is measured immediately before the cutting position and the residence time required for the strand at the position corresponding to the slab to be cut to pass through the inside of the continuous casting machine. And a correction step of correcting the cutting length based on the width of the strand, and a cutting step of cutting the strand based on the cutting length corrected in the correction step.

In the slab cutting method in the continuous casting machine according to the present invention, in the above invention, the correction step includes substituting the in-machine residence time α and the width increase rate γ of the strand into the following equation (1). A step of calculating a cutting correction coefficient β and correcting the cutting length by multiplying the cutting length by the hot correction coefficient for correcting the change in the cutting length accompanying the change in the temperature of the slab and the cutting correction coefficient β. It is characterized by including.

  The slab cutting device in the continuous casting machine according to the present invention is a slab cutting device in a continuous casting machine that cuts a strand drawn from a mold into a slab having a specified cutting length in a continuous casting machine. Based on the in-machine residence time required for the strand at the position corresponding to the slab to be cut to pass through the continuous casting machine and the width of the strand measured immediately before the cutting position, It is characterized by comprising correction means for correcting the cutting length, and cutting means for cutting the strand based on the cutting length corrected by the correcting means.

  According to the present invention, a slab can be cut with a specified weight with high accuracy.

FIG. 1 is a schematic diagram showing a schematic configuration of a slab cutting system according to an embodiment of the present invention. FIG. 2 is a flowchart showing a slab cutting process procedure according to the present embodiment. FIG. 3 is a diagram for explaining the width increase rate. FIG. 4 is a diagram showing the relationship between the predicted value of the additional weight and the actual value when a simulation for correcting the cutting length using the in-machine residence time is performed. FIG. 5 is a histogram of the weight difference between the predicted value and the actual value of the additional weight shown in FIG. FIG. 6 is a diagram showing the relationship between the predicted value of the added weight and the actual value when a simulation for correcting the cutting length using the residence time in the machine and the width increase rate is performed. FIG. 7 is a histogram of the weight difference between the predicted value and the actual value of the additional weight shown in FIG.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not limited by this embodiment. Moreover, in description of drawing, the same code | symbol is attached | subjected and shown to the same part.

  First, with reference to FIG. 1, the flow of the process in the continuous casting machine which is the object of the present embodiment will be described. As shown in FIG. 1, in a continuous casting machine, when molten steel supplied from a molten steel pan 1 to a tundish 2 is poured into a mold 3, it is solidified by cooling from the surroundings to form a shell. . The molten steel in which the shell is formed is drawn from the position immediately below the mold 3 downward in the vertical direction along the vertical portion R1 of the continuous casting machine to become a strand S. The strand S passes through a roller apron 4 on which a large number of guide rolls are arranged so as to face each other, and is cooled by a water-cooled spray (not shown) disposed along the roller apron 4 while passing through a curved portion R2 of a continuous casting machine. It is corrected in the direction and becomes a flat strand S at the horizontal portion R3 of the continuous casting machine. This strand S is cut into a slab of a predetermined length by a torch cutter 11 disposed downstream.

  Next, a schematic configuration of the slab cutting system 10 of the present embodiment will be described. As shown in FIG. 1, the slab cutting system 10 includes a torch cutter 11 that cuts the strand S and a slab that sequentially measures the width of the strand S that passes through the position of the measure roll 5 disposed on the entrance side of the torch cutter 11. It has a width meter 12, a business computer 13 that holds information for designating the cutting length of a slab, and a process computer 14 for continuous casting.

  The torch cutter 11 cuts the strand S at a position where the length actually measured by the measure roll 5 coincides with the cutting length designated together with the cutting instruction based on the cutting instruction of the slab cutting system 10 described later.

  The business computer 13 is constituted by an information processing device such as a workstation or a personal computer, and is in a cooled state calculated by a nominal unit weight based on a predetermined slab width (named slab width) or a designated weight. Information to specify the cutting length (cold value) of the slab and the cutting length (hot value) of the slab in the heated state. The size of the slab, the steel type, the hot correction coefficient set for each strand, and the like are stored in the memory.

  The continuous casting process computer 14 is constituted by an information processing apparatus such as a workstation or a personal computer. The continuous casting process computer 14 functions as a data reading unit 141, a correction unit 142, and a cutting instruction unit 143 when an arithmetic processing unit such as a CPU in the information processing apparatus executes a control program stored in the memory. . The functions of these units will be described later.

  Here, with reference to the flowchart of FIG. 2, the slab cutting process procedure by the slab cutting system 10 will be described. The flowchart in FIG. 2 starts, for example, at a timing when an operator inputs an instruction for cutting a slab, and the slab cutting process proceeds to the process of step S1.

  In the process of step S <b> 1, the data reading unit 141 reads from the business computer 13 information on a slab including a cutting length (cold value), a hot correction coefficient, and a nominal slab width. Thereby, the process of step S1 is completed and a slab cutting process progresses to the process of step S2.

  In the process of step S2, the correction unit 142 corrects the read cutting length to a hot value based on the read hot correction coefficient. Thereby, the process of step S2 is completed and the slab cutting process proceeds to the process of step S3.

  In the process of step S3, the correction unit 142 determines in step S2 based on the residence time measured separately and the width increase rate of the strand S calculated from the width of the strand S measured by the slab width meter 12. The corrected cutting length (hot value) is corrected. The correction coefficient at this time is a cutting correction coefficient β. Thereby, the process of step S3 is completed and a slab cutting process progresses to the process of step S4.

  In the process of step S4, the cutting instruction unit 143 outputs cutting instruction information including information on the cutting length (corrected cutting length) corrected in the process of step S3 to the torch cutter 11. Thereby, the process of step S4 is completed and a series of slab cutting processes are complete | finished.

  Here, a calculation method of the cutting correction coefficient β in the process of step S3 will be described. In this embodiment, considering the speed fluctuation of the strand S in the continuous casting machine, first, the length (machine length) from the meniscus (interface) of the mold 3 of the continuous casting machine to the machine end E corresponding to the final guide roll position is determined. Divided into three regions of vertical portion R1, curved portion R2 and horizontal portion R3, and the ends of the blocks obtained by dividing strand S by a predetermined length (for example, 10 cm) after reaching the respective regions The passage time required to pass through each region is measured, and the average value of passage times of all blocks corresponding to the slab to be cut is the residence time (α1, α2, α3 (min)) in each region. To do. In this case, the in-machine residence time α (min) of the strand S is represented by the sum of the residence times α1 to α3. The correction unit 142 calculates the cutting correction coefficients β1, β2, and β3 in each region by the following equation (2) based on the residence times α1, α2, and α3 in each region.

  When the residence times α1 to α3 are measured, the passage time from the start end to the end of each region is measured at intervals of the length of the divided blocks of the strand S. Therefore, the in-machine residence time α of the slab to be cut can be measured as the error range of the position of the slab to be cut by the length of the divided block of the strand S.

  Further, the correction unit 142 calculates the following equation (3) based on the width of the strand S (measured slab width) measured by the slab width meter 12 and the nominal slab width read by the data reading unit 141 from the business computer 13. The width increase rate γ (%) of the strand S defined by is calculated.

  For example, as shown in FIG. 3, when the nominal slab width is 2000 mm and the four measured slab widths measured by the slab width meter 12 are 2020 mm, 2030 mm, 2010 mm, and 2020 mm, the width of the strand S increases. The rate γ is calculated to be 1% using the representative value of the measured slab width, with an average of 2020 mm of the measured slab width as a representative value of the measured slab width of the strand S.

  Next, the correction unit 142 calculates the cutting correction coefficient β4 by the following equation (4) based on the width increase rate γ calculated by the above equation (3).

  Next, the correction unit 142 calculates the sum of β1 to β4 calculated by the above equations (2) and (4) as the cutting correction coefficient β, and calculates the corrected cutting length by the following equation (5).

  As described above, according to the slab cutting system 1 of the present embodiment, the correction unit 142 sets the cutting length in consideration of the width of the strand S measured immediately before cutting in addition to the in-machine residence time α. Since the correction is made, the slab can be cut with a specified weight including an additional weight for weight compensation with high accuracy. Therefore, the yield rate of slab can be improved significantly.

  In the above embodiment, the in-machine residence time α is defined as the sum of the residence times (α1, α2, α3) in three regions, but the number of regions to be divided is not limited to three. For example, the time during which the block of the specified length of the strand S passes through the entire length of the machine without being divided may be the residence time in the machine, or the sum of the residence times in each of the areas where the machine is divided into four or more is retained in the machine. It may be defined as time.

  Moreover, in the said embodiment, although the terminal end in the continuous casting machine at the time of measuring the residence time (alpha) in the machine is made into the machine end E, the position from the solidification completion position where the solidification of the strand S is completed to the machine end E downstream is completed. This specific position may be the end in the continuous casting machine.

(Example)
FIG. 4 is a diagram showing the relationship between the predicted value of the additional weight and the actual value when a simulation for correcting the cutting length using the in-machine residence time is performed. First, for many slab cutting examples, the explanatory variable is the in-machine residence time (α1 to α3), the objective function is the actual value of the additional weight, and the error between the actual value of the additional weight and the predicted value is minimized. Regression analysis was performed to derive the cutting correction coefficient β. Here, the cutting correction coefficient β is expressed by the sum of β1, β2, and β3 in the above equation (2), and the coefficients a, b, c, d, e, f, and g in the above equation (2) are obtained by regression analysis. , H, l were derived. FIG. 4 shows the relationship between the actual value of the additional weight and the predicted value of the additional weight calculated using the derived cutting correction coefficient β for the other 263 slab cutting examples. As the actual value of the additional weight, a hot value obtained by correcting the actually measured additional weight (cold value) with a hot correction coefficient was used. As a result, as shown in FIG. 4, the variation σ between the predicted value and the actual value of the added weight was 0.32. FIG. 5 is a histogram of the weight difference (%) between the predicted value of the additional weight and the actual value in this case.

  On the other hand, FIG. 6 is a diagram showing the relationship between the predicted value of the additional weight and the actual value when a simulation for correcting the cutting length using the in-machine residence time and the width increase rate according to the present embodiment is performed. First, for a number of slab cutting examples, the explanatory variables are the in-machine residence time and the width increase rate, the objective function is the actual value of the additional weight, and the actual value of the additional weight and the predicted value are the same as in FIG. Regression analysis was performed to minimize the error, and a cutting correction coefficient β was derived. Here, the cutting correction coefficient β is expressed by the sum of β1, β2, β3, β4 in the above equations (2) and (4), and coefficients a and b in the above equations (2) and (4) are obtained by regression analysis. , C, d, e, f, g, h, l, j. FIG. 6 shows the relationship between the actual value of the additional weight and the predicted value of the additional weight calculated using the derived cutting correction coefficient β for the other 263 slab cutting examples. As a result, as shown in FIG. 6, the variation σ between the predicted value and the actual value of the additional weight was 0.22. FIG. 7 is a histogram of the weight difference (%) between the predicted value of the additional weight and the actual value in this case.

  As shown in FIG. 6 and FIG. 7, when the cutting length is corrected using the in-machine residence time and the width increase rate, the cutting length corrected only by the in-machine residence time shown in FIG. 4 and FIG. 5. It was found that the variation between the predicted value of the added weight and the actual value is smaller than that of the case of cutting at the point. That is, it can be seen that the accuracy of the corrected cutting length by the cutting correction coefficient β is improved. Thus, it was confirmed that the cutting can be performed with a specified weight with high accuracy by the cutting correction coefficient β according to the present embodiment.

  Although the embodiment to which the invention made by the present inventor is applied has been described above, the present invention is not limited by the description and the drawings that form a part of the disclosure of the present invention according to this embodiment. That is, other embodiments, examples, operational techniques, and the like made by those skilled in the art based on this embodiment are all included in the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Molten pan 2 Tundish 3 Mold 4 Roller apron 5 Major roll 10 Slab cutting system 11 Torch cutter 12 Slab width meter 13 Business computer 14 Continuous casting process computer 141 Data reading part 142 Correction part 143 Cutting instruction part S Strand E Machine end

Claims (2)

In a continuous casting machine, a slab cutting method in a continuous casting machine for cutting a strand drawn from a mold into a slab of a cutting length having a specified weight,
The in-machine residence time α required for the strand at the position corresponding to the slab to be cut to pass through the inside of the continuous casting machine, and the expected width of the slab, which is the width of the strand measured immediately before the cutting position A cutting correction coefficient β is calculated by substituting the width increase rate γ with respect to the following equation (1), and a hot correction coefficient for correcting a change in the cutting length with a temperature change of the slab with respect to the cutting length: A correction step of correcting the cutting length by multiplying by the cutting correction coefficient β;
A cutting step of cutting the strand based on the cutting length corrected in the correcting step;
The slab cutting method in the continuous casting machine characterized by including.

In a continuous casting machine, a slab cutting device in a continuous casting machine for cutting a strand drawn from a mold into a slab of a cutting length having a specified weight,
The in-machine residence time α required for the strand at the position corresponding to the slab to be cut to pass through the inside of the continuous casting machine, and the expected width of the slab, which is the width of the strand measured immediately before the cutting position A cutting correction coefficient β is calculated by substituting the width increase rate γ with respect to the following expression (2), and a hot correction coefficient for correcting a change in the cutting length with a temperature change of the slab with respect to the cutting length: Correction means for correcting the cutting length by multiplying the cutting correction coefficient β;
Cutting means for cutting the strand based on the cutting length corrected by the correcting means;
A slab cutting device in a continuous casting machine.

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