JP2011088153A - Method for employing continuously cast slab based on quality determination - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for employing a slab based on quality determination in which quality determination information is given to a slab unit cast by a continuous casting machine and cut by a slab cutting machine installed in the outlet side of the continuous casting machine, and the slab is correctly conveyed out to the following step based on the given quality determination information so as to be treated. <P>SOLUTION: In the method for employing a continuously cast slab, when each slab is cast by a continuous casting machine, and is cut by a slab cutting machine installed in the outlet side of the continuous casting machine so as to be produced as the slab with a certain length, operational data upon the continuous casting of the slab are compared with a quality abnormality determination master and whether there is an abnormality in the quality of each slab or not is determined, and a quality abnormality code is given to the slab to which determination that an abnormality is present is given, and the conveying place of the slab is decided based on the given quality abnormality code. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is an operation for carrying out and treating a slab cast by a continuous casting machine and cut by a slab cutting machine installed on the outlet side of the continuous casting machine to a predetermined next process based on quality judgment. Regarding the method.

  The slab cast by the continuous casting machine is cut to a predetermined length required by the next hot rolling process by a slab cutting machine installed on the outlet side of the continuous casting machine, and then required Accordingly, the surface of the slab is subjected to surface care such as melting, and then paid out to the next step by a conveying means such as a freight car or a vehicle. In recent years, from the viewpoint of energy saving, it is common to pay out the cast slab to the next process in a hot state or a warm state without performing surface care.

  By the way, in the continuous casting process of steel, when the fluctuation amount of the molten metal surface in the mold becomes large, when the degree of superheat of the molten steel in the tundish becomes low, or when unevenness occurs in the slab surface temperature, etc. The quality of the slab deteriorates. In such a case, if the slab is hot-rolled according to the planned plan, defects will occur in the rolled steel product, and not only will the yield of the steel product be reduced, but also the expected amount of steel product will be obtained. Sometimes it is not possible. This problem becomes particularly apparent when the slab is dispensed to the next step without performing surface care.

  Therefore, in order to prevent such a problem, many methods for determining the quality of the slab online are proposed. For example, the amount of Al oxide produced is grasped from the amount of Al concentration fall in the molten steel, and the quality rating of the slab based on the amount of Al oxide produced (see Patent Document 1) or the measurement placed on the back of the mold A method of determining a surface defect of a slab from a measured value of a mold copper plate temperature by a temperature element (see Patent Document 2) has been proposed.

  There has also been proposed a method in which the quality information at the time of continuous casting including the quality information determined in this way is applied to each cut piece.

  In Patent Document 3, in a method of associating cast quality information collected during casting when continuously casting molten steel in a mold and cutting it into an arbitrary length to obtain a slab, a time at a constant cycle Information and casting quality information are measured and sequentially stored in the collected data storage unit, and stored in the position storage unit while adding the arrival time information when the unit virtual area arrives at the corresponding casting quality information measurement position Thus, a method has been proposed in which a unit virtual area is tracked from the casting port to the cutting position, and the casting quality information in the collected data storage unit is searched and linked from the arrival time in the tracked unit virtual area.

Japanese Patent Laid-Open No. 10-249505 International Publication No. 2000/51763 JP-A-11-285798

  However, the above Patent Document 3 has the following problems.

  Although said patent document 3 is giving the casting quality information for every cut slab unit, it does not disclose the subsequent physical distribution of the slab to which the casting quality information is given. That is, giving casting quality information to the slab is not related to the operation of the slab with the casting quality information, and how to effectively use the casting quality information for the operation of the slab. It is unknown.

  Further, the time point at which the casting quality information is given is not clear. In the case of continuous casting, not only the uncut slab stays in the continuous casting machine but also the tundish above the mold when the slab at the beginning of casting is cut in the slab for one charge. Some of the inside and ladle exist in the state of molten steel. Therefore, the casting performance of the charge is determined when all the slabs for one charge are cut. If the time at which casting quality information is given to each cut slab is the time at which the casting performance of the charge is determined, the casting quality information is not given to the slab at the beginning of casting until the casting performance is confirmed After being transported to the next process, casting quality information is given and it is necessary to send it back to another place, or it is necessary to wait in a continuous casting yard until casting quality information is given. In the meantime, the temperature of the slab also drops, and efficient operation is hindered.

  The present invention has been made in view of the above circumstances, and the object of the present invention is a slab unit cast by a continuous casting machine and cut by a slab cutting machine installed on the exit side of the continuous casting machine. Providing quality judgment information and providing a continuous casting slab operation method based on quality judgment that can quickly and accurately carry out and treat the slab to a predetermined next process based on the given quality judgment information It is to be.

  An operation method of a continuous cast slab based on quality judgment according to the first invention for solving the above-mentioned problem is cast by a continuous caster and cut by a slab cutter installed on the outlet side of the continuous caster. When it is manufactured as a slab of a certain length, the operation data at the time of continuous casting of the slab is compared with the quality abnormality determination master to determine whether there is a quality abnormality of the slab, and there is a quality abnormality It is characterized in that an abnormal quality code is assigned to the slab determined to be determined at the time of determination, and the destination of the slab is determined based on the provided abnormal quality code.

  The operation method of the continuous cast slab based on the quality determination according to the second invention is characterized in that, in the first invention, the diversion destination of the slab is set according to the assigned quality abnormality code.

  The operation method of the continuous cast slab based on the quality judgment according to the third invention is set in the first invention or the second invention, depending on the quality abnormality code assigned, to add surface maintenance of the slab. It is characterized by that.

  According to the present invention, at the time when it is cut by a slab cutting machine of a continuous casting machine and manufactured as an individual slab, the presence or absence of quality abnormality is determined, and the slab determined to have quality abnormality is determined. Since the quality abnormality code is assigned, the slab carried out from the continuous casting machine can be transported to a predetermined place corresponding to the quality abnormality code, and the operation of the slab is made efficient.

It is a figure which shows the provision method of the quality abnormal code in the continuous casting process in this invention. It is a figure which shows the operating method of the slab in the steel slab process in this invention.

  Hereinafter, the present invention will be specifically described.

  In the continuous casting process of steel, the molten steel in the ladle, which has been melted by a converter or RH vacuum degassing apparatus, is poured into the tundish, and a predetermined amount of molten steel is retained in the tundish. The molten steel in the tundish is continuously poured into the mold, and the solidified shell that has cooled and solidified in contact with the mold is continuously drawn below the mold, and cooling water is drawn onto the surface of the solidified shell, ie the slab, drawn from the mold. Each of the slabs is manufactured by forcibly cooling by spraying and cooling to the inside and then cutting with a slab cutting machine disposed on the outlet side of the continuous casting machine.

  The slab manufactured in this way is manufactured according to a manufacturing instruction based on an order from the user, and a steel product exhibits a predetermined material characteristic value by a converter, an RH vacuum degassing apparatus, or the like. It must be prepared as a chemical component and have a predetermined mass. Usually, the thickness and width of the slab are preset, so that the predetermined mass means that the slab is cut by a predetermined length.

  Also, in the continuous casting process, when the molten metal surface fluctuation in the mold becomes large, or when the superheat of the molten steel in the tundish becomes small, the flow rate of Ar gas blown to prevent the adhesion of alumina to the immersion nozzle is insufficient. When it does, it becomes impossible to ensure a predetermined slab quality. Of course, even when the slab length is short with respect to the manufacturing instruction, the target mass cannot be secured, resulting in a quality abnormality.

  In the present invention, the quality abnormality in the continuous casting process excluding the chemical component of the slab is determined, and when it is recognized that there is a quality abnormality, the quality abnormality code is given to the slab, and the assigned quality abnormality code Based on this, the operation of the slab will be decided. In addition, manufacturing instructions, determination of presence / absence of quality abnormality, provision of a quality abnormality code, operation of a slab determined to be quality abnormality, and the like are basically performed by a computer.

  First, the quality abnormality determination method in the continuous casting process will be described with reference to FIG. FIG. 1 is a diagram showing a method for assigning a quality abnormality code in a continuous casting process. In FIG. 1, CC-P / C is a process computer for continuous casting for managing the operation of a continuous casting machine. / C is a business computer for managing the entire manufacturing process of steel products, and CC is a continuous casting machine.

  In the continuous casting process, the mold width, that is, the slab width, is set based on the manufacturing instructions transmitted from B / C to CC-P / C, and prepared to the specified chemical composition using a converter or RH vacuum degasser. Then, the molten steel conveyed to the continuous casting yard is continuously cast, and the cast slab is cut based on the cutting instruction transmitted from B / C to CC-P / C together with the manufacturing instruction. Then, when the cutting of each slab is completed, the operation data at the time of continuous casting of the slab is compared with the quality abnormality determination master, and the presence or absence of the quality abnormality of the slab is automatically determined. In the determination, a threshold value is set in advance for each quality abnormality item, and the presence or absence of quality abnormality is determined by comparing with a threshold value. Although the quality abnormality determination master itself exists in the B / C, since the capacity is large, a copy plate in a range in which the continuous casting machine is involved is taken into each CC-P / C.

  Examples of the quality abnormality include, for example, fluctuation of the molten metal surface in the mold, superheat of the molten steel in the tundish, casting speed, surface temperature of the slab, and molten steel surface height in the tundish. The fluctuation of the molten metal level in the mold is judged as a quality abnormality when the fluctuation level of the molten metal level measured by the molten metal gauge is compared with the threshold value, and the degree of superheat of the molten steel in the tundish is determined by a thermocouple, etc. The temperature measurement value of the molten steel in the tundish measured continuously or periodically is compared with the threshold value, and it is determined that the quality is abnormal when the temperature becomes lower than the threshold value. The casting speed is measured from the number of rotations of the pinch roll. When the casting speed is compared with the threshold value and exceeds the upper threshold value or when the casting speed is lower than the lower threshold value, it is determined that the quality is abnormal, and the surface temperature of the slab is measured by a radiation thermometer. When the surface temperature of the steel is lower than the threshold, it is determined that the quality is abnormal, and the molten steel surface height in the tundish is determined by comparing the weight of the tundish measured by a load cell with the threshold. Lighter than By determining the quality abnormality come can be determined automatically. When the quality abnormality reaches a plurality of items, a plurality of quality abnormalities are given.

  In addition, the operation data of quality abnormal items such as the amount of fluctuation of the molten metal surface measured with the molten metal surface meter is stored in the CC-P / C sequentially based on the casting length or elapsed time, etc., and when cutting the slab, From the stored operation data of the abnormal quality item, the casting length or elapsed time region corresponding to the slab to be cut is applied to the slab. That is, the operation data of each quality abnormality item is choked on each slab by a method similar to the method proposed in Patent Document 3.

  Then, a quality abnormality code corresponding to each quality abnormality item is given to the slab determined as having a quality abnormality, and then the slab is carried out of the continuous casting machine. The assignment of the quality error code to the slab is transmitted from CC-P / C to B / C. However, the provision of this quality abnormality code is a provisional record as shown in FIG. 1. When the cutting of all slabs for one charge (CH) is completed, the casting record in charge units is calculated as CC-P / C. To B / C. A part of the provisional achievement may be corrected by inputting the casting achievement in charge unit.

  In the case of the above provisional results, the quality abnormality is determined only for items that can be automatically determined, but in the case of the input of the casting results in charge units, other quality abnormality codes that are not compatible with automatic input are used. It is also possible to input. The quality abnormality that does not correspond to automatic input is an item that is found after the casting is completed, such as a dipping nozzle hole, a fear of slab bulging due to breakage of a slab support roll, and the like.

  Next, the operation of the slab in the steel slab process, which is a process connecting the continuous casting process and the hot rolling process, will be described with reference to FIG. FIG. 2 is a diagram showing a method of operating a slab in a billet process. In FIG. 2, billet-P / C is a process computer that manages the operation of a slab in a billet process. Is the same as the business computer of FIG.

  B / C automatically handles slabs with quality error codes based on provisional results transmitted from CC-P / C using the settings that exist in the quality error processing master in B / C. To decide. Specifically, in the quality abnormality processing master, a comprehensive evaluation setting that identifies the level of diversion destination according to the level of quality abnormality of the slab, and surface maintenance is added to the slab that was not maintained in the plan. Maintenance change evaluation settings that increase the amount of cutting or cutting are provided, and based on these settings, the quality abnormality processing master automatically determines the surface treatment of the divert destination and slab, and the determination result is Apply to each slab. When a plurality of quality abnormality codes are assigned, the safety side is set for each item (selection of worse evaluation, addition of maintenance route, etc.).

  In this way, the B / C provisionally determines the physical distribution of the slab by giving the judgment results of the comprehensive evaluation setting and the maintenance change evaluation setting to each slab.

  In the slab process, the slab is transported from the continuous casting process to the next process based on the provisional decision of logistics input from B / C to the slab-P / C. In other words, slabs to be converted without surface maintenance are transported to the slab storage area in the hot rolling process, and slabs to be converted after surface maintenance are transported to the surface maintenance yard, and the slab is carefully inspected. The slab that determines the slab is conveyed to the slab inspection site, and the slab that is not diverted and is scraped is conveyed to the slab cutting site. However, slabs for which the maintenance route has not been determined are not transported, and are kept on standby until the actual casting results for each charge unit become clear.

  When the casting results (positive results) in the charge unit are input to the B / C from the CC-P / C, the B / C officially determines the logistics and transmits the information to the billet-P / C. In the billet process, the slab maintenance route and the transport destination are corrected based on the official logistics decision input from B / C to billet-P / C.

  In the present invention, the continuous cast slab is operated in this way. And, in the present invention, at the time when it is cut by a slab cutting machine of a continuous casting machine and manufactured as individual slabs, the presence or absence of quality abnormality is determined, and when slabs are determined to have quality abnormality, Since the quality abnormality code is assigned, the slab carried out from the continuous casting machine can be transported to a predetermined place corresponding to the quality abnormality code, and the operation of the slab is made efficient.

Claims (3)

  Operation data at the time of continuous casting of the slab when it is cast by a continuous casting machine, cut by a slab cutting machine installed on the outlet side of the continuous casting machine, and manufactured as a slab of a certain length In comparison with the quality abnormality determination master, the presence or absence of quality abnormality of the slab is determined, and a quality abnormality code is assigned to the slab determined to have quality abnormality at the time of determination, based on the assigned quality abnormality code A method for operating a continuous cast slab based on quality judgment, wherein a destination of the slab is determined.   The method for operating a continuous cast slab based on quality judgment according to claim 1, wherein a diversion destination of the slab is set according to the assigned quality abnormality code.   The method for operating a continuous cast slab based on the quality judgment according to claim 1 or 2, characterized in that addition of surface care of the slab is set according to the assigned quality abnormality code.

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