JP2012040612A - Cast slab cutting method in continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately cut a cast slab to a requested length matching a requested weight.SOLUTION: During continuous casting, a strand S pulled out by a pinch roll 8 from a mold 5 is cut by a cutting device 9 into cast slabs each with a length having a necessary requested weight obtained by correcting a nominal unit weight by a correction coefficient. At this time, a surface temperature-measuring instrument 24 that measures the surface temperature of the strand is provided between the pinch roll and the cutting device. Regarding the plurality of the cut cast slabs P, from cast-in condition information including the surface temperature measured by the surface temperature-measuring instrument, and the actual measured weight of each cast slab, an auxiliary coefficient multiplied to each cast-in condition included in a formula for calculating the correction coefficient is obtained, the correction coefficient applied to the calculation of the cutting length of each cast slab is obtained from each auxiliary coefficient and the cast-in condition information regarding the cast slab to be cut next, and the strand is cut to the requested cast slab length using the correction coefficient.

Description

  The present invention relates to a slab cutting method in continuous casting, and more particularly, a slab length suitable for a required billing weight requested (required) in a subsequent process for a strand drawn from a mold during continuous casting operation in a steelmaking factory. The present invention relates to a slab cutting method in continuous casting, which is preferably applied when cutting.

  FIG. 1 schematically shows a conventional continuous casting facility. As shown in this figure, a ladle 1 for transporting molten steel is transferred onto a tundish 3 for temporarily storing the molten steel via a long nozzle 2.

  A mold 5 is connected to the bottom of the tundish 3 via an immersion nozzle 4. A vertical part and a curved part following the mold 5 are arranged along a plurality of guide rolls 6. For example, three pinch rolls 8 are connected to the horizontal portion formed on the downstream side of the curved portion.

  Downstream of these pinch rolls 8 is a torch car 9 that melts the strand S into a slab of a predetermined length while moving in synchronism with the casting speed, and further downstream is a weight measuring instrument that measures the slab P that has been cut. 10 are respectively arranged.

  In such a casting facility, the molten steel 11 transported by the ladle 1 is poured into the tundish 3 by the long nozzle 2 at the bottom of the ladle 1 and then poured into the mold 5 via the immersion nozzle 4. When the shell 12 is formed while being cooled in the mold 5 and sequentially solidified from the surroundings, the strand 12 is drawn out as a strand S from the lower end, and is cooled by cooling water from the spray band 7 and passes through a curved portion. It is guided to the horizontal part and becomes a straight strand S.

  This strand S is sent to a torch car 9 by a pinch roll 8, where it is melted (cut) into a predetermined length slab (slab) P and then conveyed to a weight measuring device 10, where the slab weight after cutting is determined. Measured. A series of these operations is controlled by a process computer 20 (in the figure, a process computer).

  In such continuous casting, the target length of the slab (slab) to be cut (hereinafter also referred to as the slab cutting length or the slab billing length) is nominal according to the billing weight required in the subsequent process. It is calculated | required from the unit weight (henceforth a nominal single weight) and the correction coefficient which correct | amends this (for example, refer patent documents 1-3).

  Here, the nominal unit weight is the weight per unit length of the strand obtained by using the specific area determined from the cross-sectional area of the mold and the molten steel. For example, the cross-sectional area of the strand is immediately after being drawn from the mold and cooled. Since it changes after being done, correction is made to the unit weight of the strand immediately before cutting using a correction coefficient.

  The conventionally used correction coefficient is obtained by measuring the weight of a previously cut slab and taking into account various fluctuation factors related to weight fluctuation, and using the correction coefficient thus obtained, The slab cutting length to be cut next was corrected and obtained.

  For example, in Patent Document 2, a contribution rate of casting condition information is obtained from casting condition information such as casting speed and steel type, and a weight measurement result regarding a plurality of cut slabs. The correction coefficient which concerns on this is calculated | required, and the slab is cut | disconnected to the length used as the required weight calculated | required using this correction coefficient.

JP-A-56-95456 JP-A-6-114519 JP 2001-47204 A

  However, the conventional slab cutting method uses feedback control based on the simple casting conditions such as casting speed and steel type and the measurement result of the actual slab penetration weight (actual weight). There was a problem that it was not always accurately reflected in the length.

  In other words, it is very difficult for existing sensors to grasp items that affect slab cooling, such as the state of rolls in a continuous casting machine. Therefore, continuous casting operations with many disturbance factors can be completely performed only by casting condition information. For example, the method of Patent Document 2 cannot reduce the weight deviation (variation) of the actual slab.

  In addition, during casting, abnormalities such as detachment of representative components of molten steel and abnormalities in casting caused abnormalities such as scraping the surface of the slab after casting. Even so, the cutting length was not corrected on-line for the slab. Therefore, after cutting the slab to the target length, if the slab surface is cleaned with a scarf machine or a grinder, the slab does not reflect the weight loss due to maintenance, so there is a shortage with respect to the requested weight. Will end up.

  Due to the above problems, when a large error occurs in the slab after cutting with respect to the requested weight, all the corresponding slabs are unclaimed surplus materials (hereinafter referred to as “unusable”) that cannot be used in subsequent processes. This is also referred to as a surplus material), resulting in long-term unusable stock, or diversion to another billing, and unnecessary parts are scrapped, leading to a decrease in yield.

  The present invention has been made to solve the above-described conventional problems, and provides a slab cutting method in continuous casting that can cut a slab to a requested length corresponding to the requested weight more accurately than in the past. The task is to do.

  In the invention of claim 1, the required claim weight obtained by correcting the nominal unit weight of the strand drawn by the pinch roll from the mold during continuous casting with the correction coefficient calculated based on the casting condition information is obtained. In a slab cutting method in continuous casting in which a slab having a length is cut by a cutting device, a surface temperature measuring device for measuring the surface temperature of the strand is installed between the pinch roll and the cutting device, and the slab is cut. For a plurality of cast slabs, an auxiliary for multiplying each casting condition included in the formula for calculating the correction coefficient from the casting condition information including the surface temperature measured by the surface temperature measuring instrument and the actual weight of each slab. A coefficient is obtained, and from each of the obtained auxiliary coefficients and casting condition information on the slab to be cut next, a correction coefficient applied to the calculation of the cutting length of the slab is obtained, and Seeking slab length to be required according to the weight by using a positive coefficient, by cutting the strands into the template strip length is obtained by solving the above problems.

  The invention of claim 2 is also a required claim obtained by correcting the nominal unit weight of a strand drawn by a pinch roll from a mold during continuous casting with a correction coefficient calculated based on casting condition information. In a slab cutting method in continuous casting in which a slab having a length having a weight is cut by a cutting device, a maintenance loss caused by performing surface maintenance determined to be necessary during casting for a plurality of cut slabs. The auxiliary coefficient to be multiplied by each casting condition included in the equation for calculating the correction coefficient is obtained from the casting condition information including the actual weight of each slab, and the obtained auxiliary coefficient and the casting to be cut next. When determining the correction coefficient to be applied to the calculation of the cutting length of the slab from the casting condition information on the slab, when it is determined during casting that the corresponding slab requires surface care after cutting , The casting condition information related to the slab is reflected in the maintenance loss associated with the surface maintenance, and the slab length corresponding to the required billing weight is obtained using the correction coefficient, and the strand is cut to the slab length. Thus, the above-mentioned problem is similarly solved.

  The invention according to claim 3 is the required claim obtained by further correcting the nominal unit weight of the strand drawn by the pinch roll from the mold during continuous casting with a correction coefficient calculated based on casting condition information. In the slab cutting method in continuous casting in which a slab having a length having a weight is cut by a cutting device, a surface temperature measuring device for measuring the surface temperature of the strand is installed between the pinch roll and the cutting device, and Regarding a plurality of cut slabs, information on casting conditions including the surface temperature measured by the surface temperature measuring instrument and the maintenance loss generated by performing surface maintenance determined to be necessary during casting, and each casting From the measured weight of the piece, an auxiliary coefficient to be multiplied by each casting condition included in the equation for calculating the correction coefficient is obtained, and the obtained auxiliary coefficient and the slab to be cut next are obtained. When determining the correction coefficient to be applied to the calculation of the cutting length of the slab from the casting condition information to be performed, when it is determined during casting that the corresponding slab needs surface care after cutting, The casting condition information relating to the slab is reflected in the maintenance loss associated with the surface care, and the slab length that is a required billing weight is obtained using the correction factor, and the strand is cut to the slab length. By doing so, the above-mentioned problem is solved in the same manner.

  According to a fourth aspect of the present invention, in the first, second, or third aspect of the invention, when continuously casting a plurality of strands while injecting molten steel into a plurality of molds from the same tundish, the tundish is charged for each strand. The molten steel more than the total billed weight obtained by adding all the total billed weights obtained by adding up the weights is charged, and the estimated casting length is calculated from the total requested weight for each strand, and based on the planned casting length of each strand. Thus, the casting speed is controlled so that the casting time is the same between the strands.

  A fifth aspect of the present invention is the invention according to the first, third, or fourth aspect, wherein the surface temperature included in the casting condition information is a plurality of positions in the width direction with respect to strands at positions corresponding to a target slab. The average surface temperature is obtained by averaging the temperatures measured at predetermined intervals in the length direction.

  The invention of claim 6 relates to the relationship between the surface temperature measured by the surface temperature measuring instrument and the actually measured solidification shrinkage rate for the plurality of cut slabs according to the invention of claim 1, 3 or 4. Based on the above, the solidification shrinkage rate for each surface temperature is indexed on the basis of the value for a predetermined surface temperature, and the index is reflected in the correction coefficient. As described above, the surface temperature is actually measured by the surface temperature measuring device immediately before cutting the slab, so that the slab cutting length determined from the casting condition information is finally corrected based on the immediately preceding surface temperature. It becomes possible.

  A seventh aspect of the invention is the invention of the second, third, or fourth aspect, wherein the maintenance loss included in the casting condition information has a surface having a desired thickness for a strand at a position corresponding to a target slab. The weight is the same as the shaving weight when shaving.

  The invention of claim 8 further has a required claimed weight obtained by correcting the nominal unit weight of the strand drawn from the mold at the time of continuous casting using a correction coefficient calculated based on casting condition information. In a slab cutting method in continuous casting in which a slab of length is cut by a cutting device, when continuously casting a plurality of strands while injecting molten steel from the same tundish into a plurality of molds, the tundish is subjected to each strand. The molten steel more than the total billed weight obtained by adding all the billed weights obtained by adding the billed weights is charged, and the expected casting length is calculated from the total requested weight for each strand, and the estimated casting length of each strand is calculated. Based on the above, the problems are similarly solved by controlling the casting speed so that the casting time is the same between the strands.

  According to the first aspect of the present invention, the surface temperature of the strand immediately before cutting corresponding to the slab (slab) (hereinafter also referred to as the slab surface temperature) is constantly measured, so that the slab accompanying a change in the surface temperature, for example, a decrease. Since it is possible to reflect the degree of contraction in the correction coefficient, it is possible to accurately cut to the requested length corresponding to the requested weight.

  According to the invention of claim 2, since it becomes possible to reflect the slab maintenance loss generated after cutting as a correction coefficient, it is possible to cut accurately to the requested length corresponding to the requested weight.

  According to the invention of claim 3, the effects of the inventions of claims 1 and 2 can be exhibited simultaneously.

  According to the invention of claim 8, when continuously casting a plurality of strands at the same time, casting of each strand can be finished simultaneously, and as a result, each strand can be accurately cut to the requested length.

Schematic diagram showing the outline of conventional continuous casting equipment The schematic diagram which shows the outline | summary of the continuous casting installation applied to one Embodiment which concerns on this invention The perspective view which shows typically the state which is measuring the slab surface temperature with a surface temperature measuring device (A) sectional view and (B) principal part expanded sectional view for demonstrating the powder entrainment accompanying a molten metal surface fluctuation | variation The perspective view which shows the state which is carrying out surface maintenance of the slab

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 2 is a schematic diagram conceptually showing a vertical-curved type continuous casting facility to which a slab cutting method in continuous casting according to an embodiment of the present invention is applied.

  In the continuous casting equipment applied to the present embodiment, molten steel is simultaneously injected from a same tundish into a plurality of (here, two) molds, and strands are cast simultaneously from the respective molds. Since the other basic configuration is the same as that shown in FIG. 1, description will be made using the same reference numerals for the same portions.

  The molten steel 11 injected into the tundish 3 from the ladle 1 through the long nozzle 2 is led to the two molds 5 through the immersion nozzle 4 and cooled by the respective molds 5 to solidify from the surroundings to form a shell. 12 is formed, it becomes a continuous slab (strand) S, and is arranged along a plurality of guide rolls 6 constituting a vertical portion downstream from the vicinity of the lower end of the mold and a curved portion following the vertical portion. While being cooled by the cooling water from the spray band 7 consisting of a plurality of water-cooled sprays (not shown), it is drawn out in an arc shape and guided downstream.

  Then, it is conveyed to the torch car 9 by the three pinch rolls 8 in the horizontal portion, and melted and cut into a slab (slab) P having a predetermined weight by the torch. The cut slab (slab) is conveyed to the weight measuring device 10, and an actual weight is measured. Since the two casting lines shown in the drawing are symmetrical, a part of the left line is omitted. In the figure, two casting lines are provided back to back, but they may be provided side by side on the same side.

  The continuous casting facility of the present embodiment is controlled by a process computer 20, and the requested weight is transmitted to the process computer 20 from a host computer (not shown) and set.

  The process computer 20 includes a thermometer 21 attached to the tundish 3, a flow meter 22 and a thermometer 23 attached to the spray band 7, and a tachometer and a weight meter attached to the most upstream pinch roll 8a. A measurement result is input from each (not shown), and the molten metal level is input from the molten metal level sensor 25 in the mold 5.

  Further, in this continuous casting equipment, a surface temperature measuring device 24 for measuring the surface temperature of the slab is attached to the exit side of the most downstream pinch roll 8c, and the measurement result by the surface temperature measuring device 24 is also sent to the process computer 20 in the same manner. It is designed to be entered.

Here, the main features of the slab cutting method of the present embodiment will be described.
(1) The casting speed is controlled for each strand so that the sum of the claimed weights for each strand can be produced with the same heat in the converter without excess or deficiency as much as possible. At that time, the amount of main raw material (hot metal or scrap) charged to the converter (or electric furnace) per one heat should be the minimum value corresponding to the total requested weight at the time of cooling in consideration of the yield. It is desirable to adjust.
(2) Further, during casting, in addition to a method of cutting into a slab having a required billing weight using a corrected unit weight obtained by correcting the nominal unit weight by a correction coefficient calculated by casting condition information, The slab surface temperature immediately before cutting is measured by the slab surface temperature measuring device 24 installed on the exit side of the pinch roll 8 installed in the continuous casting machine.

  From the measurement results, for example, as shown in Table 1, the slab solidification shrinkage rate is indexed so that it can be added and reflected in the correction coefficient. The indexing will be described in detail later.

  As shown in the table above, when the surface temperature of the slab (slab) is high (in this example, 751 ° C or higher), the planned cutting length calculated from casting condition information, etc. is corrected without correction. However, if the slab surface temperature is low (750 ° C or less in this example), the slab is strongly cooled, so the solidification shrinkage increases and the weight of the actual slab decreases. did. Therefore, when the slab surface temperature is low, it is necessary to correct the slab cutting length to be cut immediately after the temperature measurement by extending the requested cutting length by dividing the requested weight by the nominal unit weight. Will be able to.

  That is, when the surface temperature is very low, the solidification shrinkage increases accordingly, so that the slab cutting length can be corrected with an index so that it can be made longer than the planned cutting length in the case of high temperature. It is valid. When the surface temperature is low, the index shown in Table 1 is longer than the expected cutting length when the surface temperature is high, so that the weight loss due to solidification shrinkage can be compensated. Is used as a reference (1.000), and the solidification shrinkage rate experimentally obtained for each temperature at intervals of 50 ° C. of 750 ° C. or less is indexed, and each index is a coefficient for each temperature obtained by experiment.

  Here, an example in which the reference temperature for indexing is 751 ° C. or higher is shown, but the present invention is not limited to this.

  Specifically, the surface temperature measuring device 24 measures the temperature of the upper surface of the slab, and calculates the average slab surface temperature. The average slab surface temperature refers to the temperature at any number in the width direction (in the figure, the center in the width direction and several hundreds of mm from the center to the left and right) as shown in the image using arrows in FIG. It is the value measured and measured at a pitch of 500 mm in the direction.

Using the surface temperature actually measured in this way, for example, if the average slab surface temperature is 640 ° C., using the correction formula for the corresponding expected cutting length in the right column in Table 1,
Cutting length = (billed weight / nominal unit weight) / 0.985
Calculate as

The auxiliary coefficient A4 in the equation (2) described later corresponds to the introduction of this concept to the calculation of the correction coefficient.
(3) In addition, if it is determined that the surface of the slab after cutting is to be cleaned with a scarf or grinder during casting due to the occurrence of abnormalities such as detachment of the molten steel or fluctuations in the mold surface, the operator Reflects the maintenance loss in the correction coefficient, and cuts the slab to a length corresponding to the requested weight.

  For example, as shown in FIGS. 4 (A) and 4 (B), when the molten metal surface fluctuation occurs, the mold powder 13 covering the molten steel surface in the mold is entrained and trapped under the slab surface layer. It is generally known that

  Therefore, normally, in continuous casting, the level of the molten metal surface (molten steel surface) in the mold is continuously monitored. Since the mold powder trapped under the surface layer of the slab becomes a surface defect in the rolling process, it is necessary to remove the surface of the slab by scarfing (melting) using, for example, a scarf machine 14 as shown in FIG. The amount of welding can be removed sufficiently with a slab surface of about 2 mm on one side. As a result of the cutting, the weight of the slab, which was initially planned, becomes lighter and the required product cannot be collected.

Therefore, when it is judged that slab maintenance (melting) is necessary, the slab cutting length is extended to compensate for the weight lost by slab maintenance. For example, when 250 mm thick x 1,900 mm wide x 8,000 mm long slab requires 2 mm single-sided maintenance, the weight change before and after slab cleaning is
(0.25 × 1.90 × 8.0 × 7.85)
-(0.246 x 1.896 x 8.0 x 7.85)
= 0.53 tons
It becomes.
Therefore, this weight loss is compensated by cutting length extension by the following equation.

0.53 ÷ (0.25 × 1.90 × 7.85) = 0.14
→ 8,000 + 140 = 8,140

  Therefore, the cutting length is changed from 8,000 mm to 8,140 mm.

The auxiliary coefficient A5 in the equation (2) described later corresponds to the introduction of this concept to the calculation of the correction coefficient.

  Next, the operation of this embodiment will be described.

  First, the billing weight is transmitted to the process computer 20 from a host computer (not shown) and set.

  At that time, the amount of main raw material charged to the refining furnace (converter or electric furnace) is determined based on the yield by type of steel determined based on the latest molten steel yield results and operating conditions (whether scraps are generated due to switching between different steel types or nozzle replacement). To do.

  Then, since it is the case of multiple strands, the total requested weight of each strand and the expected casting length are calculated, and the reference casting speed is determined so that the casting time for each strand becomes the same.

  Here, since there are two strands, for example, if the A strand and the B strand are used, the two are cast at the same time, so the reference casting speed is determined by the following equation (1).

A strand planned casting length ÷ A strand standard casting speed = B strand planned casting length ÷ B strand standard casting speed (1)

  At that time, consideration should be given from the planning stage so that the standard casting speed does not deviate from the adjustable range in actual operation. Specifically, it means that the molten steel temperature is not lowered too slowly, and conversely, it is too fast so that solidification is not completed and breakout is not induced.

  Scheduling is of course scheduled to connect continuous casting, but it is necessary to pre-determine how fast and how long a 1-heat molten steel is to be cast. In order to do this, the casting speed for each strand is determined from the sum of the requested slab cutting lengths for each strand as the expected casting speed, and is set as the reference casting speed. As for the case where the casting speed changes in the middle, for example, when it passes through the converter, RH, and continuous casting facilities, it takes time to adjust the components in RH, so the ladle for the next heat is preliminarily prepared. Since it is determined that it is later than the time, the casting speed may be reduced to connect to the next heat.

  In addition, when the casting speed is changed in the middle, for example, when it is decelerated, it has been empirically found that the solidification shrinkage of the slab increases. So it is guaranteed by cutting length extension.

  As described above, by controlling by the formula (1), in the slab continuous casting machine having a plurality of strands, when the total slab weight (total cutting length) differs for each strand, the casting speed is controlled. Otherwise, the strand with the smaller total billed weight (total cut length) will produce an unclaimed surplus slab, and another strand will run out of billed weight (billed length). However, this situation can be avoided.

  Next, the slab cutting length is corrected from the casting information input to the process computer 20 and the slab surface temperature measurement result by the slab surface temperature measuring device 24.

  As the casting information, the actual casting speed Vc obtained from the rotational speed of the pinch roll 8a by the tachometer, the steel type determined by the molten steel composition and application, the number of times the mold is used, the guide roll 6 measured at the time of loading the dummy bar before casting, etc. Roll interval data, and the casting temperature which is a measurement result of the molten steel temperature in the tundish 3 by the thermometer 21.

  In addition, the cutting allowance determined from the number of times the crater of the torch car 9 is used, the pressing weight of the pinch roll 8 measured by the weigh scale, the secondary cooling water temperature by the thermometer 23 installed in the secondary cooling water pipe, and the like. Due to the specific water amount per unit time calculated from the actual cooling water amount obtained by the flow meter 22, the measurement result of the slab surface temperature by the surface temperature measuring device 24 installed on the outlet side of the pinch roll 8c, the casting abnormality, etc. The presence or absence of slab care is input to the process computer 20 as casting information. The surface temperature measuring device 24 is installed on the exit side of the pinch roll 8 in order to eliminate the influence of secondary cooling water and recuperation of the spray zone 7 for cooling.

  The measurement result by the surface temperature measuring device 24 is used for quantifying the solidification shrinkage state of the slab (see Table 1 above), and measures the point that cannot be grasped only by the conditions of the casting speed and the amount of secondary cooling water. can do.

  Also, if it is found during casting that the slab needs to be cleaned with a scarf machine 14 or a grinder after cutting due to abnormalities during casting, etc., information on the necessary maintenance method before cutting is provided in units of slabs. The weight loss associated with maintenance is reflected in the correction factor.

  Reflecting the casting conditions such as the above measurement results, a correction coefficient used for calculating the slab cutting length is calculated, and the torch car 9 is positioned at a predetermined position corresponding to the slab cutting length calculated using the correction coefficient. Move and cut the slab. Further, after cutting, the weight (actually measured) weight is read by the weight measuring device 10.

  Hereinafter, an equation for obtaining a correction coefficient used for correction calculation of the slab cutting length by the process computer 20 is shown below.

Correction coefficient = A0 x (actual casting speed) + A1 x (steel grade) +
A2 x (ΔT in tundish) + A3 x (pinch roll pressing weight) +
A4 x (Slab surface temperature measurement result by surface temperature measuring instrument) +
A5 x (weight loss due to slab care) + A6 x (secondary cooling water / water temperature) +
A7 x (secondary cooling water volume (specific water volume per unit time)) +
A8 x (mold usage count) + A9 x (roll gap data) +
A10 x (Number of times used for torch cutter crater) (2)

Here, A1 to A10 are auxiliary coefficients obtained by performing multiple regressions each time from the measurement results of each item (casting conditions) and the actual penetration weight of the slab. A correction coefficient relating to the slab to be cut is obtained by the above equation (2) in which each item is multiplied by a value obtained by multiplying the auxiliary coefficient.

  Furthermore, the cutting length with respect to the set requested weight is obtained by the following equation (3) using the correction coefficient obtained by the equation (2).

Cutting length = Requested weight ÷ (Nominal unit weight × Correction factor) (3)
The correction coefficient obtained by the equation (2) is corrected by saving the slab penetration weight and casting conditions as data every time the slab is cut, deleting the oldest data, and performing a new multiple regression each time. Review the coefficients.

  Next, the embodiment will be further described with specific examples.

(1) Applicable materials (steel type, components, dimensions, etc.)
Thick plate slab, 40k general-purpose medium carbon steel Dimensions: A strand slab size = 250mm thickness x 1,904mm width x requested cut length B strand slab size = 250mm thickness x 2,304mm width x requested cut length Requested weight: A strand = 150ton, B strand = 165ton

(2) Applicable equipment / applicable process / applicable work Applicable equipment: Vertical-bending slab continuous caster (2 strands) as shown in FIG. 1 in a steelmaking factory, the vertical part is about 3,000 mm from the meniscus position.
Logistics flow: Converter → RH → Slab continuous casting machine → Thick plate factory

(3) Operation / processing conditions Total converter charge determined from the requested weight: (150 + 165) ÷ 0.95 = 331.6ton
Casting length determined from the requested weight: A strand = 40.0 m, B strand = 36.5 m
Casting speed range = 0.7 m / min to 1.2 m / min During casting, the slab surface temperature is measured by a surface temperature measuring device on the pinch roll exit side.

  <Convert to slab shape from temperature distribution at 3 locations in width direction (see Fig. 3) at 500mm pitch in length direction>

(4) Results
(i) Casting speed adjustment to make casting time the same in both A and B strands
(ii) A strand = 0.95 m / min, B strand = 0.865 m / min Casting time = 42.2 min

  As shown in Table 2 below, by applying the method of the present invention, cutting is performed with high accuracy with respect to the claimed weight as compared with the conventional method.

  Further, even when the claimed weight varies depending on the strands, the rate of generation of unclaimed surplus materials can be reduced as follows by adjusting the casting speed.

  According to the present invention, the on-line measurement using the surface temperature measuring instrument and the presence or absence of slab maintenance due to casting abnormalities are reflected, so that the slab length can be accurately cut according to the requested weight. As a result, it is possible to improve the casting yield.

DESCRIPTION OF SYMBOLS 1 ... Ladle 2 ... Long nozzle 3 ... Tundish 4 ... Immersion nozzle 5 ... Mold 6 ... Guide roll 7 ... Spray belt 8 ... Pinch roll 9 ... Torch car 10 ... Slab weight measuring instrument 11 ... Molten steel 12 ... Solidified shell 13 ... Mold Powder 20 ... Process computer 21 ... Thermometer 22 ... Flow meter 23 ... Thermometer 24 ... Surface temperature measuring instrument 25 ... Hot water level sensor

Claims (8)

During continuous casting, a strand drawn from a mold by a pinch roll is obtained by correcting the nominal unit weight by a correction coefficient calculated based on casting condition information, and having a length having a required billing weight. In the slab cutting method in continuous casting cut by a cutting device,
Between the pinch roll and the cutting device, while installing a surface temperature measuring device for measuring the surface temperature of the strand,
With respect to a plurality of cut slabs, from the casting condition information including the surface temperature measured by the surface temperature measuring instrument and the actual weight of each slab, each casting condition included in the equation for calculating the correction coefficient Find the auxiliary coefficient to multiply,
From each of the obtained auxiliary coefficients and casting condition information on the slab to be cut next, a correction coefficient to be applied to the calculation of the cutting length of the slab is obtained,
Using the correction factor, find the slab length to achieve the required claim weight,
A slab cutting method in continuous casting, wherein the strand is cut into the slab length. During continuous casting, a strand drawn from a mold by a pinch roll is obtained by correcting the nominal unit weight by a correction coefficient calculated based on casting condition information, and having a length having a required billing weight. In the slab cutting method in continuous casting cut by a cutting device,
With respect to a plurality of cut slabs, the correction coefficient is calculated from the casting condition information including the maintenance loss generated by performing the surface maintenance determined to be necessary during casting and the measured weight of each slab. Find the auxiliary coefficient to multiply each included casting condition,
When obtaining the correction coefficient to be applied to the calculation of the cutting length of the slab from each auxiliary coefficient obtained and the casting condition information on the slab to be cut next,
During casting, when it is determined that surface care is required after cutting the corresponding slab, the casting condition information related to the slab is reflected in the maintenance loss associated with the surface care,
Using the correction factor, find the slab length to achieve the required claim weight,
A slab cutting method in continuous casting, wherein the strand is cut into the slab length. During continuous casting, a strand drawn from a mold by a pinch roll is obtained by correcting the nominal unit weight by a correction coefficient calculated based on casting condition information, and having a length having a required billing weight. In the slab cutting method in continuous casting cut by a cutting device,
Between the pinch roll and the cutting device, while installing a surface temperature measuring device for measuring the surface temperature of the strand,
Regarding a plurality of cut slabs, information on casting conditions including the surface temperature measured by the surface temperature measuring instrument and the maintenance loss generated by performing surface maintenance determined to be necessary during casting, and each casting From the actual measured weight of the piece, find the auxiliary coefficient to be multiplied by each casting condition included in the equation for calculating the correction coefficient,
When obtaining the correction coefficient to be applied to the calculation of the cutting length of the slab from each auxiliary coefficient obtained and the casting condition information on the slab to be cut next,
During casting, when it is determined that surface care is required after cutting the corresponding slab, the casting condition information related to the slab is reflected in the maintenance loss associated with the surface care,
Using the correction factor, find the slab length to achieve the required claim weight,
A slab cutting method in continuous casting, wherein the strand is cut to the slab length. When continuously casting multiple strands while pouring molten steel into multiple molds from the same tundish,
The tundish is charged with molten steel that is equal to or greater than the total requested weight obtained by adding up the total requested weight obtained by adding the requested weight for each strand;
The planned casting length is calculated from the total requested weight for each strand, and the casting speed is controlled based on the planned casting length of each strand so that the casting time is the same between the strands. The slab cutting method in the continuous casting according to claim 1, 2 or 3.   The surface temperature included in the casting condition information is an average obtained by averaging the temperatures measured at predetermined intervals in the length direction of the surfaces of a plurality of positions in the width direction for the strands at positions corresponding to the target slabs. The slab cutting method in continuous casting according to claim 1, wherein the surface temperature is a surface temperature.   With respect to the plurality of cut slabs, the solidification shrinkage rate for each surface temperature is determined for a predetermined surface temperature based on the relationship between the surface temperature measured by the surface temperature measuring instrument and the measured solidification shrinkage rate. The slab cutting method in continuous casting according to claim 1, wherein the index is indexed with reference to the value, and the index is reflected in the correction coefficient.   The maintenance loss included in the casting condition information is a shaving weight when the surface is shaved by a desired thickness with respect to a strand at a position corresponding to a target slab. A slab cutting method in continuous casting according to 3 or 4. During continuous casting, the strand drawn from the mold is obtained by correcting the nominal unit weight by the correction coefficient calculated based on the casting condition information, and the slab having the required requested weight is cut by a cutting device. In the slab cutting method in continuous casting to cut,
When continuously casting multiple strands while pouring molten steel into multiple molds from the same tundish,
The tundish is charged with molten steel that is equal to or greater than the total requested weight obtained by adding up the total requested weight obtained by adding the requested weight for each strand;
The planned casting length is calculated from the total requested weight for each strand, and the casting speed is controlled based on the planned casting length of each strand so that the casting time is the same between the strands. A slab cutting method in continuous casting.