Temperature raising device, rolling facility, and temperature raising method

Abstract

In a temperature raising device that raises the temperature of a slab in a facility including two or more strands, provided are: a first temperature raising device 501 that is provided on a rolling line between a first strand 401 and a rough rolling mill 70; a second temperature raising device 502 that is provided on a temperature raising line to which the slab is transported from a second strand 402 different from the first strand 401, the temperature raising line being different from the rolling line; and a first slab transportation device 40 that is configured to be capable of moving the slab between the downstream side of the first temperature raising device 501 in the rolling line and the downstream side of the second temperature raising device 502 in the temperature raising line, and the first temperature raising device 501 and the second temperature raising device 502 have induction heating devices. Accordingly, the temperature drop of the cast slab transported on the strand not directly connected to the rough rolling mill in the continuous casting machine including a plurality of strands is reduced as compared with a conventional one, and the temperature raising efficiency before sending the cast slab to the rough rolling mill is improved.

Description

TEMPERATURE RAISING DEVICE, ROLLING FACILITY, AND TEMPERATURE RAISING METHODThe present invention relates to a temperature raising device, a rolling facility, and a temperature raising method.Patent Document 1 describes a device including a casting station which includes a rolling mill including at least one rolling mill stand, at least a first casting line, and at least a second casting line, each line being operable to produce respective continuous strands and elongated intermediate products, the first casting line being directly aligned with the rolling mill, the first casting line being configured to supply continuous casting strands or cast elongated intermediate products to the rolling mill, the second casting line being not aligned with the rolling mill, in which device bidirectional transfer means for transfer is further provided in a first direction from the second casting line to the first casting line or in a second direction from at least the second casting line to a cooling bed, in order to align the elongated intermediate products of the second casting line with the rolling mill.[PTL 1] JP-6370926-BAs a prior art that includes two casting lines (strands) and transports a billet from a first casting line to a rolling mill, there is a technique described in, for example, Patent Document 1.In the prior art, not only a billet transported from the first casting line is heated up by an induction heater provided on the downstream side of the first casting line, but also a billet transported from a second casting line is heated up after shifting movement to the first casting line.However, in the above prior art, there is a problem that it takes time for the billet transported on the second casting line to be transported to reach the induction heater and a temperature drop becomes large.The present invention provides a temperature raising device, a rolling facility, and a temperature raising method that can reduce a temperature drop of a cast slab transported on a strand not directly connected to a rough rolling mill in a continuous casting machine including a plurality of strands as compared with a conventional one and improve the temperature raising efficiency before sending the cast slab to the rough rolling mill.Means for Solving the ProblemThe present invention includes a plurality of means for solving the above problem, and as an example, provided is a temperature raising device that raises a temperature of a steel cast piece in a facility including two or more strands, and includes: a first temperature raising device that is provided on a rolling line between a first strand and a rough rolling mill; a second temperature raising device that is provided on a temperature raising line to which the cast piece is transported from a second strand different from the first strand, and the temperature raising line being different from the rolling line; and a first transportation device that is configured to be capable of moving the cast piece between a downstream side of the first temperature raising device in the rolling line and a downstream side of the second temperature raising device in the temperature raising line, in which the first temperature raising device and the second temperature raising device have induction heating devices.Advantages of the InventionAccording to the present invention, it is possible to reduce a temperature drop of a cast slab transported on a strand not directly connected to a rough rolling mill in a continuous casting machine including a plurality of strands as compared with a conventional one. Problems, configurations, and effects other than those described above will be clarified by the following description of the embodiments.FIG. 1 is a diagram for depicting an outline of a rolling facility including a temperature raising device of a first embodiment.FIG. 2 is a diagram for depicting an outline of a rolling facility including a different temperature raising device of the first embodiment.FIG. 3 is a diagram for depicting an outline of a flow of transporting a slab in the rolling facility including the different temperature raising device of the first embodiment.FIG. 4 is a diagram for depicting an outline of a flow of transporting the slab in the rolling facility including the different temperature raising device of the first embodiment.FIG. 5 is a diagram for depicting an outline of a flow of transporting the slab in the rolling facility including the different temperature raising device of the first embodiment.FIG. 6 is a diagram for depicting an outline of a flow of transporting the slab in the rolling facility including the different temperature raising device of the first embodiment.FIG. 7 is a diagram for depicting the relationship between the casting velocity and the heating time of an IH slab heater in one temperature raising device and the relationship between the casting velocity and the slab supply pitch of a continuous casting machine.FIG. 8 is a diagram for depicting an outline of a rolling facility including a temperature raising device of a second embodiment.FIG. 9 is a diagram for depicting an outline of a flow of transporting a slab in the rolling facility including the temperature raising device of the second embodiment.Modes for Carrying Out the InventionHereinafter, embodiments of a temperature raising device, a rolling facility, and a temperature raising method of the present invention will be described by using the drawings. It should be noted that in the drawings used in the description, the same or corresponding constitutional elements will be given the same or similar characters, and repeated descriptions of these constitutional elements will be omitted in some cases.<First Embodiment>A first embodiment of a temperature raising device, a rolling facility, and a temperature raising method of the present invention will be described by using FIG. 1 and FIG. 7.First, the overall configuration of the temperature raising device and the rolling facility including the same will be described by using FIG. 1. FIG. 1 is a diagram for depicting an outline of the temperature raising device and the rolling facility including the same of the present invention.A rolling facility 1 in FIG. 1 includes a continuous casting machine 12, a temperature raising device, and a rough rolling mill 70 for rolling a slab (cast piece) with the temperature raised by the temperature raising device, and has a configuration in which the temperature raising device for the slab is arranged between the continuous casting machine 12 and the rough rolling mill 70.The continuous casting machine 12 has a first strand 401 and a second strand 402. In the present embodiment, the same line as a rolling line is defined as the first strand 401, and the line side that is not the rolling line is defined as the second strand 402. The slab of the second strand 402 is transported to the rolling line (first strand) by a first slab transportation device 40, and then transported in the direction of the rough rolling mill 70 and the like. Further, a strand thermometer 403 for measuring the temperature of the slab transported on the first strand 401 and the second strand 402 is provided.Although omitted for illustration reasons, a ladle is mounted on a ladle turret 10, and molten steel is poured into a tundish from the ladle. The tundish has two outlets, and the molten steel is poured into both molds of the first strand 401 and the second strand 402 from the outlets.Since the continuous casting machine 12 has two strands, cast slabs are cast in two lines and divided into slabs having a desired length by a torch cutting machine 14 located on the exit side of the continuous casting machine 12.In the case where the cast slab cannot be transported to the rough rolling mill 70 due to troubles in the rolling facility or the quality of the slab, a second slab transportation device 42 and a fourth slab transportation device 46 to be described later are used to transport the slab as a rejected material to a storage yard for rejected slab 50. In the storage yard for rejected slab 50, the rejected material is stored, and repair and inspection of the rejected material are performed if necessary.The temperature raising device of the present embodiment depicted in FIG. 1 is a device for raising the temperature of a slab in a facility including two or more strands, and is configured using a first temperature raising device 501, a second temperature raising device 502, a first slab transportation device 40, a second slab transportation device 42, a third slab transportation device 44, a fourth slab transportation device 46, a controller 90, and the like.The first temperature raising device 501 is provided in the rolling line between the first strand 401 in the continuous casting machine 12 and the rough rolling mill 70, and has a first IH slab heater 20, a first soaking device 30, a fourth soaking device 36, and the like. The first temperature raising device 501 is arranged on the same line as the first strand 401 of the continuous casting machine 12.The slab transported from the continuous casting machine 12 toward the direction of the rough rolling mill 70 is heated up to a desired temperature by at least the first IH slab heater 20, is then transported to the first soaking device 30 or the fourth soaking device 36, and the temperature distribution in the cross section of the slab is uniformized and the rolling timing is adjusted while suppressing the heat radiation from the slab in the first soaking device 30 and the fourth soaking device 36.The first soaking device 30 is a device provided on the exit side of the slab in the rolling line of the first IH slab heater 20 and using the retained heat of the slab as the heat source, and the fourth soaking device 36 is a device provided on the entry side of the slab in the rolling line of the first IH slab heater 20 and using the retained heat of the slab as the heat source.The second temperature raising device 501 is provided between the second strand 402 different from the first strand 401 in the continuous casting machine 12 and the rough rolling mill 70, and has a second IH slab heater 22, a second soaking device 32, a third soaking device 34, and the like.The second soaking device 32 is a device provided on the exit side of the slab in a temperature raising line of the second IH slab heater 22 and using the retained heat of the slab as the heat source, and the third soaking device 34 is a device provided on the entry side of the slab in the temperature raising line of the second IH slab heater 22 and using the retained heat of the slab as the heat source.The second temperature raising device 502 is arranged in the temperature raising line (the same line as the second strand 402) to which the slab is transported from the second strand 402 and which is different from the rolling line, and in the case of FIG. 1, when the temperature of the slab flowing from the second strand 402 is raised, or when the temperature rise of the slab is insufficient in the first IH slab heater 20 of the first temperature raising device 501, the second temperature raising device 502 is provided for heating up in the second IH slab heater 22 and for heat retention in the second soaking device 32, the third soaking device 34, and the like.In addition, when the slabs supplied from the first strand 401 and the second strand 402 are heated up by the first IH slab heater 20 and the second IH slab heater 22, respectively, the fourth soaking device 36 and the third soaking device 34 operate to suppress the temperature drop of the slabs in the case where the insertion to the first IH slab heater 20 and the second IH slab heater 22 is performed at a low velocity. Since the insertion velocity in the case of temperature difference compensation heating to be described later is slow compared with the slab transportation velocity, the fourth soaking device 36 and the third soaking device 34 effectively operate in suppressing the temperature drop in that case.It should be noted that the configuration in which each of the first temperature raising device 501 and the second temperature raising device 502 has two heat retaining devices is depicted, but both of them may include either one or three of more devices. In addition, one or more IH slab heaters may be used.In the first IH slab heater 20, the second IH slab heater 22, the first soaking device 30, the second soaking device 32, the third soaking device 34, and the fourth soaking device 36, a table roller (omitted for illustration reasons) is provided, and the slab can be moved back and forth in the rolling direction.The first IH slab heater 20 and the second IH slab heater 22 can uniformize the temperature in the cross section while uniformizing the temperature rise in the longitudinal direction of the slab by reciprocating (oscillating) the slab back and forth in the rolling direction.Since a tundish becomes large in size when the interval between the first strand 401 and the second strand 402 becomes wide, the interval between the first strand 401 and the second strand 402 is relatively close to each other.Therefore, in FIG. 1, the first IH slab heater 20 and the second IH slab heater 22 are placed at different positions in the casting direction. Accordingly, the interval between the first temperature raising device 501 and the second temperature raising device 502 in the direction perpendicular to the rolling direction can be narrowed, the second strand 402 and the second temperature raising device 502 can be placed on the same line without increasing the size of the tundish, the first IH slab heater 20 and the second IH slab heater 22 can be prevented from interfering with each other, and the respective maintenance spaces can be secured.The first soaking device 30, the second soaking device 32, the third soaking device 34, and the fourth soaking device 36 can employ a configuration in which the slab is surrounded with a panel configured using a reflector and a heat insulating material to suppress the escape of heat from the slab arranged therein and to promote to uniformize the temperature inside the slab. It is also possible to employ a structure in which a heat insulating material such as a refractory is combined with an iron shell on the outside without providing a reflector. In addition, it is also effective in shortening the time of raising the temperature to arrange heating means therein and use the heating means to raise the temperature inside the heat retaining device at the start of the operation. Although gas heating may be used as the internal heating means, direct CO2emissions can be suppressed by using electric heaters.Even in these first soaking device 30, the second soaking device 32, the third soaking device 34, and the fourth soaking device 36, the temperature in the cross section can be uniformized while uniformizing the temperature rise in the longitudinal direction of the slab by reciprocating (oscillating) the slab back and forth in the rolling direction.The first slab transportation device 40 is configured to be capable of moving the slab between the downstream side of the first temperature raising device 501 in the rolling line and the downstream side of the second temperature raising device 502 in the temperature raising line, and the first slab transportation device 40 is also configured to transport the slab from the temperature raising line toward the rolling line and to transport the slab from the rolling line toward the temperature raising line.On the other hand, the second slab transportation device 42 is configured to be capable of moving the slab between the upstream side of the first temperature raising device 501 in the rolling line and the upstream side of the second temperature raising device 502 in the temperature raising line.The third slab transportation device 44 is configured to be capable of moving the slab between the storage yard for rejected slab 50 for storing the slab and the downstream side of the second temperature raising device 502 in the temperature raising line. The fourth slab transportation device 46 is configured to be capable of moving the slab between the storage yard for rejected slab 50 and the upstream side of the second temperature raising device 502 in the temperature raising line. It should be noted that it is possible to have a configuration in which only one of the third slab transportation device 44 and the fourth slab transportation device 46 is provided.A thermometer 201 in the first temperature raising device is a thermometer provided in the first temperature raising device 501 to measure the temperature of the slab. For example, it is configured to measure the surface temperature of the slab in the first IH slab heater 20.A thermometer 203 in the second temperature raising device is a thermometer provided in the second temperature raising device 502 to measure the temperature of the slab in the second temperature raising device 502. For example, it is configured to measure the surface temperature of the slab in the second IH slab heater 22.A storage yard thermometer 205 is a thermometer provided in the storage yard for rejected slab 50 to measure the surface temperature of the slab in the storage yard for rejected slab 50.The controller 90 predicts the average temperature of the slab and the temperature of the center of the slab on the basis of the measurement result of the temperature of the slab in one or more of the above-described strand thermometer 403, thermometer 201 in the first temperature raising device, thermometer 203 in the second temperature raising device, and the storage yard thermometer 205, and decides the transportation destination of the slab on the basis of the measured surface temperature and the predicted internal temperature.In addition, the controller 90 decides a transportation velocity in addition to a transportation direction in each device within the temperature raising device of the slab and controls the velocity thereof.After finishing the heating in the temperature raising device, at first, since an oxidation scale is generated on the surface of the slab by high-temperature heating prior to rolling in the rolling facility 1, the scale on the surface is removed by a scale breaker 60 that removes the scale by spraying high-pressure water on the surface of the slab before rolling, reverse rolling is performed by the single rough rolling mill 70, unidirectional rolling is performed by a plurality of finishing rolling mill trains 75, strip cooling is performed by a run out table 80, and winding is performed by a down coiler 85. In the rolling facility 1, it is possible to arrange a plurality of rough rolling mills 70.Next, another configuration of the temperature raising device of the present embodiment will be described by using FIG. 2. FIG. 2 is a diagram for depicting an outline of another configuration of the temperature raising device and the rolling facility including the same of the present invention.As similar to the rolling facility 1 depicted in FIG. 1, a rolling facility 1A in FIG. 2 includes a continuous casting machine 12, a temperature raising device, and a rough rolling mill 70 for rolling a slab with the temperature raised by the temperature raising device, and has a configuration in which the temperature raising device for the slab is arranged between the continuous casting machine 12 and the rough rolling mill 70.The temperature raising device in the rolling facility 1A in FIG. 2 has a configuration in which the interval between a first temperature raising device 501A and a second temperature raising device 502A is wider than the interval between the first temperature raising device 501 and the second temperature raising device 502 of the temperature raising device in the rolling facility 1 depicted in FIG. 1, and the interval between a first IH slab heater 20 and a second IH slab heater 22 is wide.Accordingly, even if the first IH slab heater 20 and the second IH slab heater 22 are in the same position with respect to the casting direction as depicted in FIG. 2, interference with each other is prevented. In addition, it is also possible to secure the maintenance spaces of the first IH slab heater 20 and the second IH slab heater 22.With such a configuration, the sizes of a first soaking device 30A and a third soaking device 34A in the rolling direction are compact as compared with the sizes of the first soaking device 30 and the third soaking device 34 in the rolling direction.Here, if the first IH slab heater 20 and the second IH slab heater 22 are in the same position with respect to the casting direction, the interval thereof may be wider than the interval between the two strands. Since the tundish becomes large in size when the interval between the two strands is widened, the interval between the two strands is set so that the tundish does not become large in size in FIG. 2.In the case of the temperature raising device of the rolling facility 1A in FIG. 2, a controller 90A can allow a second slab transportation device 42 to transport a slab cast by a second strand 402 to the same line as the second temperature raising device 502A, the temperature of the slab is then raised by the second temperature raising device 502A, and the slab can be transported to the rolling line by a first slab transportation device 40.Here, at least one of the first slab transportation device 40 and the second slab transportation device 42 can transport the slab between a storage yard for rejected slab 50 and the first temperature raising device 501A or the second temperature raising device 502A by using a third slab transportation device 44 and a fourth slab transportation device 46 together.Accordingly, when a trouble occurs on the rough rolling mill 70 side or there is a defect in the quality of the slab, the slab can be transported to the storage yard for rejected slab 50 by the first slab transportation device 40 and a third slab transportation device 44, or the second slab transportation device 42 and a fourth slab transportation device 46. In addition, when the slab in the storage yard for rejected slab 50 can be rolled, the slab can be transported from the storage yard for rejected slab 50 to the first temperature raising device 501A or the second temperature raising device 502A, heated up by these temperature raising devices, and then transported to the rolling line.In the case of the temperature raising device in FIG. 1, since the slab of the second strand 402 need not be transported by the second slab transportation device 42, the temperature drop amount of the slab cast by the second strand 402 can be made smaller than the case where the temperature raising device in FIG. 2 is provided.On the other hand, in the case of the temperature raising device in FIG. 2, the facility length of the temperature raising device in the rolling direction can be shortened as compared with the temperature raising device in FIG. 1, and thus the temperature drop amount of the slab cast by the first strand 401 can be made small as compared with the configuration in FIG. 1.Next, a temperature raising method of a cast slab in the rolling facilities 1 and 1A including the temperature raising device according to the present embodiment will be described with reference to FIG. 3 to FIG. 7. FIG. 3 to FIG. 6 are diagrams for depicting an outline of a flow of transporting a slab in the rolling facility 1A depicted in FIG. 2, and FIG. 7 is a diagram for depicting the relationship between the casting velocity and the heating time of the IH slab heater in one temperature raising device and the relationship between the casting velocity and the slab supply pitch of the continuous casting machine.Here, a flow of transportation in the rolling facility 1A depicted in FIG. 2 will be described as an example, but it is obvious that the similar transportation can be realized even by the rolling facility 1 depicted in FIG. 1.As depicted in FIG. 3, the slab cast by the first strand 401 is heated up by the first IH slab heater 20 of the first temperature raising device 501A that is the rolling line, and transported to the rough rolling mill 70. Similarly, the slab cast by the second strand 402 is heated up by the second IH slab heater 22 of the second temperature raising device 502A in the temperature raising line, moved from the downstream side thereof toward the downstream side of the first temperature raising device 501A in the rolling line, and transported to the rough rolling mill 70.As a different route, as depicted in FIG. 4, the slab cast by the first strand 401 is heated up by the first temperature raising device 501A and transported to the rough rolling mill 70. In addition, the slab cast by the second strand 402 is transported to the first temperature raising device 501A by the second slab transportation device 42, heated up by the first temperature raising device 501, and transported to the rough rolling mill 70. In this case, the second temperature raising device 502A is not used.For example, the slab cast by the continuous casting machine 12 is adjusted by the first temperature raising device 501A and the second temperature raising device 502A to the temperature at which the slab can be rolled, but in the case where the casting velocity is fast, the temperature drop amount of the slab is reduced, and it is possible to heat up the slabs produced by two strands in one temperature raising device. In this case, it is advantageous that the casting - heating - rolling operation can be continued even if there is a defect in either temperature raising device. In addition, it is also advantageous that either temperature raising device can be maintained during the operation.On the other hand, in the case where the casting velocity is slow, the temperature drop amount of the slab becomes large, and thus the facility is made to heat up the slab produced by one strand in one temperature raising device.In addition, by allowing the slabs cast by both the first strand 401 and the second strand 402 to pass through the first temperature raising device 501A in the rolling line, it is possible to reduce the difference in the slab temperature on the exit side of the temperature raising device between the slabs, and it is possible to reduce the difference in the rolling temperature between the slabs, so that the rolling can be more stably performed.Here, although not illustrated, there is also a temperature raising method that uses the second temperature raising device 502A and does not use the first temperature raising device 501A.Thus, the controller 90 determines whether the slab transported from the second strand 402 is transported to either the first temperature raising device 501 or the second temperature raising device 502 on the basis of the temperature of the slab measured by the strand thermometer 403 and transported on the first strand 401 and the second strand 402 and the temperature of the slab at the timing of entering the rough rolling mill 70, and can switch the transportation direction of the slab.Further, as another flow, as depicted in FIG. 5, in the case where the transportation direction of the slab transported from the second strand 402 is switched to the rolling line, the controller 90 can transport the slab stored in the storage yard for rejected slab 50 to the temperature raising line by using the third slab transportation device 44 or the fourth slab transportation device 46.In addition, the controller 90 can raise the temperature of the slab transported from the storage yard for rejected slab 50 by induction heating in the temperature raising line, and move the slab with the temperature raised in the temperature raising line from the downstream side of the second temperature raising device 502A in the temperature raising line toward the downstream side of the first temperature raising device 501A in the rolling line. In this case, the slab transported from the storage yard for rejected slab 50 can be reciprocated in the temperature raising line to raise the temperature thereof.Further, the controller 90 can transport the slab transported from the second strand 402 to the rolling line by using the second slab transportation device 42 or can stop manufacturing the slab on the second strand 402 while the temperature of the slab transported from the storage yard for rejected slab 50 is raised by the second temperature raising device 502A.The rolling facility 1A has the ability to roll the slabs supplied from the three routes depicted in FIG. 5.For example, during casting in the continuous casting machine 12, the slab cast by the first strand 401 is heated up by the first temperature raising device 501A, and the slab cast by the second strand 402 is also transported to the first temperature raising device 501A by the second slab transportation device 42, heated up by the first temperature raising device 501A, and transported to the rough rolling mill 70.In addition, since the temperature of the slab in the storage yard for rejected slab 50 is lower as compared with the slab transported from the continuous casting machine 12, it takes time to raise the temperature, and thus the slab is transported to the second temperature raising device 502A by the fourth slab transportation device 46, heat retaining and heating are repeated by the third soaking device 34, the second IH slab heater 22, and the second soaking device 32 in the second temperature raising device 502A, and the temperature of the slab is raised. After the heating of the slab transported from the storage yard for rejected slab 50 is completed in the second temperature raising device 502A, the slab is transported to the rolling line by the first slab transportation device 40.In FIG. 5, the slab is transported from the storage yard for rejected slab 50 to the second temperature raising device 502A by the fourth slab transportation device 46 and transported to the rolling line by the first slab transportation device 40, but the slab can be transported to the second temperature raising device 502A by the third slab transportation device 44 and transported to the rolling line by the first slab transportation device 40, or if the heating of the slab during casting is not affected, the slab can be transported to the first temperature raising device 501A by the second slab transportation device 42 and transported to the rough rolling mill 70 via the first temperature raising device 501A.Further, in FIG. 5, when the first temperature raising device 501A can heat up the cast slabs of the two strands as described above, the cast slab of the storage yard for rejected slab 50 can be heated up by the second temperature raising device 502A, but in the case where the casting velocity of the continuous casting machine 12 is reduced during operation and the temperature of the cast slabs is reduced, the cast slabs of the two strands cannot be heated up to the temperature at which the cast slabs can be rolled by the first temperature raising device 501A alone in some cases. In this case, the second temperature raising device 502A gives priority to the heating of the cast slab of the second strand 402, and the heating of the cast slab of the storage yard for rejected slab 50 can be interrupted. In this case, in the case where the casting velocity of the continuous casting machine 12 is increased and the first temperature raising device 501A can heat up the cast slabs of the two strands, the second temperature raising device 502A resumes the heating of the cast slab of the storage yard for rejected slab 50.Here, in the case where it is not necessary to heat up and roll the cast slab of the storage yard for rejected slab 50 and even in the case where the first temperature raising device 501A can heat up the cast slabs of the two strands, the cast slab of the first strand 401 can be heated up by the first temperature raising device 501A and the cast slab of the second strand 402 can be heated up by the second temperature raising device 502A.As still another flow, as depicted in FIG. 6, the slab cast by the first strand 401 is heated up by the first IH slab heater 20 in the first temperature raising device 501A, transported to the second temperature raising device 502A by the first slab transportation device 40, heated up by the second IH slab heater 22, transported to the first temperature raising device 501A by the second slab transportation device 42, heated up by the first IH slab heater 20, and then transported to the rough rolling mill 70.In addition, the slab cast by the second strand 402 is transported to the first temperature raising device 501A by the second slab transportation device 42, heated up by the first IH slab heater 20 in the first temperature raising device 501A, transported to the second temperature raising device 502A by the first slab transportation device 40, heated up by the second IH slab heater 22 after being transported from the downstream side, transported to the first temperature raising device 501A by the second slab transportation device 42, heated up by the first IH slab heater 20, and then transported to the rough rolling mill 70.With this heating, a total of three times of heating in the IH slab heaters can be performed. Accordingly, the standby time of the slab can be reduced and the temperature drop can be suppressed.FIG. 7 is a diagram for depicting the relationship between the casting velocity and the heating time (s) of the IH slab heater of one temperature raising device and the slab supply pitch (s) of the continuous casting machine. The heating time of the IH slab heater depicted in FIG. 7 is an example. Although the heating time can be shortened by increasing the size of the IH slab heater and improving the specifications, the balance is herein considered as a production facility. A simulation was performed with a slab thickness of 235 mm and a slab width of 1860 mm.In FIG. 7, “white diamond” represents the heating time when two slabs of two strands are heated up by one IH slab heater, “white circle” represents the heating time when one slab of one strand is heated up by one IH slab heater, “black square” represents the slab supply pitch of the continuous casting machine when a slab having a length of 12 m is supplied from each strand to each of two IH slab heaters, and “black triangle” represents the slab supply pitch of the continuous casting machine when a slab having a length of 6 m is supplied from each strand to each of two IH slab heaters.As depicted in FIG. 7, in the case of the slab having a length of 12 m, since the heating time represented by “white circle” is shorter than the supply pitch represented by “black square” at at least a casting velocity of 1.2 m / min or faster, it can be understood that it is possible to heat up one slab in one temperature raising device.Further, in a region A in FIG. 7, since the heating time when two slabs of two strands represented by “white diamond” are heated up by one IH slab heater is shorter than the supply pitch represented by “black square”, it can be understood that it is possible to heat up the two slabs of the two strands in one IH slab heater.Further, in the region A in FIG. 7, it can also be understood that it is possible to heat up the slabs of the two strands in one temperature raising device as depicted in FIG. 4 and FIG. 5. Then, as depicted in FIG. 5, it can also be understood that it is possible to heat up the slab of the storage yard for rejected slab 50 by the second temperature raising device 502.In addition, in a region B in FIG. 7, in the case of the slab having a length of 6 m, since the heating time represented by “○” is longer than the supply pitch represented by “▲” at 1.4 m / min or slower, it is assumed that the slabs are accumulated between the continuous casting machine and the temperature raising device when the supply of the slab having a length of 6 m continues. Therefore, it can also be understood that it is necessary to make such adjustments as supplying a long slab after the slab having a length of 6 m.Here, since there is a temperature difference between the top end and the rear end of the slab, the heating in the IH slab heater is performed by a combination of overall heating and temperature difference compensation heating to reduce the temperature difference. As the slab length is shorter, the temperature difference between the top end and the rear end of the slab is smaller and the time required for the temperature difference compensation heating can be shortened, but the overall heating is hardly affected by the slab length. Further, considering that the heating time required for the overall heating is longer than the time for the temperature difference compensation heating, the heating time is expressed as the same even in the case where the slab length is different.Next, the effects of the present embodiment will be described.In the temperature raising device that raises the temperature of the slab in the facility including the two or more strands of the above-described first embodiment of the present invention, provided are: the first temperature raising device 501 that is provided on the rolling line between the first strand 401 and the rough rolling mill 70; the second temperature raising device 502 that is provided on the temperature raising line to which the slab is transported from the second strand 402 different from the first strand 401 and which is different from the rolling line; and the first slab transportation device 40 that is configured to be capable of moving the slab between the downstream side of the first temperature raising device 501 in the rolling line and the downstream side of the second temperature raising device 502 in the temperature raising line, and the first temperature raising device 501 and the second temperature raising device 502 have the induction heating devices. In particular, since the first slab transportation device 40 is configured to transport the slab from the temperature raising line toward the rolling line, the slab heated up by the second temperature raising device 502 not directly connected to the rough rolling mill can be quickly transported to the rolling line, and thus the temperature drop of the cast slab transported on the strand not directly connected to the rough rolling mill can be reduced as compared with the conventional one, and the temperature raising efficiency of the cast slab can be improved as compared with the conventional temperature raising device.Further, since the second slab transportation device 42 that is configured to be capable of moving the slab between the upstream side of the first temperature raising device 501 in the rolling line and the upstream side of the second temperature raising device 502 in the temperature raising line is further provided, it is possible to employ such an operation configuration that, in the case where the temperature of the cast slab can be raised in one temperature raising device, the temperature is raised only in one temperature raising device, and it is possible to perform such flexible response that the operation does not need to be stopped at the time of a failure of one temperature raising device, and the maintenance of one temperature raising device can be performed during the operation.In addition, since at least one of the third slab transportation device 44 that is configured to be capable of moving the slab between the storage yard for rejected slab 50 for storing the slab and the downstream side of the second temperature raising device 502 in the temperature raising line, and the fourth slab transportation device 46 that is configured to be capable of moving the slab between the storage yard for rejected slab 50 and the upstream side of the second temperature raising device 502 in the temperature raising line is further provided, the efficient temperature rise of the slab stored in the storage yard for rejected slab 50 can also be realized.Further, the controller 90 or 90A that determines whether the slab transported from the second strand 402 is transported to either the first temperature raising device 501 or the second temperature raising device 502 on the basis of the temperature of the slab transported on the first strand 401 and the second strand 402 and the temperature of the slab at the timing of entering the rough rolling mill 70, and switches the transportation direction of the slab is further provided, it is possible to realize the temperature rise of the cast slab corresponding to the conditions such as the casting condition in the continuous casting machine 12 and the rolling condition in the rough rolling mill 70.In addition, at least one of the third slab transportation device 44 that is configured to be capable of moving the slab between the storage yard for rejected slab 50 for storing the slab and the downstream side of the second temperature raising device 502 in the temperature raising line, and the fourth slab transportation device 46 that is configured to be capable of moving the slab between the storage yard for rejected slab 50 and the upstream side of the second temperature raising device 502 in the temperature raising line is further provided, and in the case where the transportation direction of the slab transported from the second strand 402 is switched to the rolling line, the controller 90 or 90A transports the slab stored in the storage yard for rejected slab 50 to the temperature raising line by using the third slab transportation device 44 or the fourth slab transportation device 46, so that the efficient temperature rise of the slab stored in the storage yard for rejected slab 50 can be realized.Further, the fourth slab transportation device 46 that is configured to be capable of moving the slab between the storage yard for rejected slab 50 for storing the slab and the upstream side of the second temperature raising device 502A in the temperature raising line is further provided, and the downstream side of the second strand 402 is connected to the second slab transportation device 42, so that the distance of the rolling line in the rolling direction can be advantageously shortened, and the temperature drop amount of the slab cast by the first strand 401 can be reduced.In addition, since the second slab transportation device 42 that is configured to be capable of moving the slab between the upstream side of the first temperature raising device 501 or 501A in the rolling line and the upstream side of the second temperature raising device 502 or 502A in the temperature raising line, and the controller 90 or 90A that is configured to transport the slab transported from the second strand 402 to the rolling line by using the second slab transportation device 42 or stop manufacturing the slab on the second strand 402 while the temperature of the slab transported from the storage yard for rejected slab 50 is raised by the second temperature raising device 502 or 502A are further provided, it is possible to suppress the occurrence of the cast slab waiting for temperature rise in the transportation device and the strand, and realize the more efficient temperature rise of the cast slab.<Second Embodiment>A temperature raising device, a rolling facility, and a temperature raising method of a second embodiment of the present invention will be described by using FIG. 8 and FIG. 9. FIG. 8 is a diagram for depicting an outline of the rolling facility including the temperature raising device of the second embodiment, and FIG. 9 is a diagram for depicting an outline of a flow of transporting a slab in the rolling facility including the temperature raising device of the second embodiment.In a rolling facility 1B of the present embodiment depicted in FIG. 8, the second slab transportation device 42 in the temperature raising device in the rolling facility 1 depicted in FIG. 1 is omitted, and a first temperature raising device 501B is provided closer to the first strand 401 side. Therefore, each configuration in the first temperature raising device 501B is basically the same as that in the first temperature raising device 501. On the other hand, each configuration in a second temperature raising device 502B is substantially the same as that in the second temperature raising device 502 except that the size of a third soaking device 34B in the rolling direction is small as compared with that of the third soaking device 34.In this case, a controller 90B can be configured to stop manufacturing the slab by the second strand 402 while the temperature of the slab transported from the storage yard for rejected slab 50 is raised by the second temperature raising device 502B.Next, a temperature raising method of a cast slab in the rolling facility 1B including the temperature raising device according to the present embodiment will be described by using FIG. 9.As depicted in FIG. 9, during casting by the continuous casting machine 12, the slab cast by the first strand 401 is heated up by the first temperature raising device 501B and transported to the rough rolling mill 70. In addition, the slab cast by the second strand 402 is transported to the second temperature raising device 502B, heated up by the second temperature raising device 502B, and transported to the rough rolling mill 70.In addition, the slab of the storage yard for rejected slab 50 is transported to the second temperature raising device 502B by the fourth slab transportation device 46, heat retaining and heating are repeated by the third soaking device 34B, the second IH slab heater 22, and the second soaking device 32 in the second temperature raising device 502B, and the temperature of the slab is raised. Since the temperature of the slab transported from the storage yard for rejected slab 50 is low as compared with that of the slab transported from the continuous casting machine 12, it takes time to raise the temperature. After the heating of the slab is completed in the second temperature raising device 502B, the slab is transported to the rolling line by the first slab transportation device 40.It should be noted that in the rolling facility 1B including the temperature raising device of the present embodiment, since the slab transportation device for transporting the slab from the second strand 402 to the first temperature raising device 501B side on the upstream side of the second temperature raising device 502B is omitted, it is required that the second strand 402 does not produce when the slab of the storage yard for rejected slab 50 is heated up by the second temperature raising device 502B.For example, in the rolling facility 1B of the present embodiment, stopping the manufacture of the cast slab on the second strand 402 may be preliminarily set in consideration of the production schedule. More specifically, when a wide slab is cast at a high velocity, the production volume is increased even in production by one strand. In this case, the slab is not cast by the second strand 402, but is cast only by the first strand 401 and heated up by the first temperature raising device 501B, and the slab of the storage yard for rejected slab 50 can be heated up by the second temperature raising device 502B.In addition, casting by two strands is selected, and when the casting velocity is lowered during casting by the second strand 402, for example, in the case where an abnormality occurs in the formation of a solidified shell in the mold during casting and the casting velocity is lowered to prevent breakout, it may be difficult to heat up the cast slabs of the two strands only by the first temperature raising device 501B. At this time, in the case where the heating of the cast slab transported from the storage yard for rejected slab 50 is to be continued, the manufacture of the cast slab by the second strand 402 may be stopped. That is, the supply of molten steel to the second strand 402 is stopped, the cast slab remaining in the second strand 402 is switched to be temporarily heated up by the second temperature raising device 502B, and the heating of the cast slab transported from the storage yard for rejected slab 50 is resumed after the second temperature raising device 502B finishes the heating of the cast slab of the second strand 402.It should be noted that even if the casting of the second strand 402 is stopped and only the first strand 401 continues the casting, the molten steel supplied from the upstream can maintain a temperature preferable for casting, which is one condition for stopping the casting of the second strand 402.FIG. 9 exemplifies a configuration in which the slab is transported from the storage yard for rejected slab 50 to the second temperature raising device 502B by the fourth slab transportation device 46 and transported to the rolling line by the first slab transportation device 40, but in this case, the third slab transportation device 44 can be omitted. In addition, it is also possible to employ a configuration in which the fourth slab transportation device 46 is omitted and the slab is transported to the second temperature raising device 502B by the third slab transportation device 44.Other configurations and operations are substantially the same as those of the temperature raising device, the rolling facility, and the temperature raising method of the above-described first embodiment, and the details thereof are omitted.Even in the temperature raising device, the rolling facility, and the temperature raising method of the second embodiment of the present invention, the effects substantially similar to those of the temperature raising device, the rolling facility, and the temperature raising method of the above-described first embodiment can be obtained. In addition, in the configuration of the present embodiment, since the second strand 402 and the second temperature raising device 502B can be placed in the same line, the distance between the continuous casting machine 12 and the rough rolling mill 70 can be shortened as compared with the configuration of the first embodiment. Therefore, the temperature drop amount of the slab can be reduced, and any of the second slab transportation device 42, the third slab transportation device 44, and the fourth slab transportation device 46 can be omitted, so that the entire facility can be downsized and the facility cost can be reduced.In addition, by further providing the controller 90B configured to stop the manufacture of the slab by the second strand 402 while the temperature of the slab transported from the storage yard for rejected slab 50 is raised by the second temperature raising device 502B, it is possible to suppress the occurrence of a cast slab waiting for temperature rise in the transportation device or the strand, and realize the more efficient temperature rise of the cast slab.Here, the slab is heated in order to reach target temperature of not only surface but also average, center of thickness, and etc. by measurement of surface temperature and estimation and control using online process model. Online process model can consider histories of route of slab, transition of temperature, etc.<Other>It should be noted that the present invention is not limited to the above embodiments and includes various modified examples. The above embodiments have been described in detail to clearly explain the present invention, and are not necessarily limited to those having all the described configurations. In the above description, the case where the cast piece is a slab has been explained, but cases where the cast piece is a billet, bloom, and beam blank, etc. are also included in the present invention.In addition, it is also possible to replace some configurations of one embodiment with configurations of another embodiment, or to add a configuration of one embodiment to a configuration of another embodiment. In addition, it is also possible to add, delete, or replace other configurations for some configurations of each embodiment.Description of Reference Characters1, 1A, 1B: Rolling facility10: Ladle turret12: Continuous casting machine14: Torch cutting machine20: First IH slab heater22: Second IH slab heater30, 30A: First soaking device32: Second soaking device34, 34A, 34B: Third soaking device36: Fourth soaking device40: First slab transportation device (first transportation device)42: Second slab transportation device (second transportation device)44: Third slab transportation device (third transportation device)46: Fourth slab transportation device (fourth transportation device)50: Storage yard for rejected slab60: Scale breaker70: Rough rolling mill75: Finishing rolling mill train80: Run out table85: Down coiler90, 90A, 90B: Controller201: Thermometer in first temperature raising device203: Thermometer in second temperature raising device205: Storage yard thermometer401: First strand402: Second strand403: Strand thermometer501, 501A, 501B: First temperature raising device502, 502A, 502B: Second temperature raising device

Claims

1. A temperature raising device that raises a temperature of a steel cast piece in a facility including two or more strands, the temperature raising device comprising: a first temperature raising device that is provided on a rolling line between a first strand and a rough rolling mill; a second temperature raising device that is provided on a temperature raising line to which the cast piece is transported from a second strand different from the first strand, the temperature raising line being different from the rolling line; and a first transportation device that is configured to be capable of moving the cast piece between a downstream side of the first temperature raising device in the rolling line and a downstream side of the second temperature raising device in the temperature raising line, wherein the first temperature raising device and the second temperature raising device have induction heating devices.

2. The temperature raising device according to claim 1, wherein the first transportation device is configured to transport the cast piece from the temperature raising line toward the rolling line.

3. The temperature raising device according to claim 1, further comprising: a second transportation device that is configured to be capable of moving the cast piece between an upstream side of the first temperature raising device in the rolling line and an upstream side of the second temperature raising device in the temperature raising line.

4. The temperature raising device according to claim 1, further comprising: at least one of a third transportation device that is configured to be capable of moving the cast piece between a storage yard for storing the cast piece and the downstream side of the second temperature raising device in the temperature raising line, and a fourth transportation device that is configured to be capable of moving the cast piece between the storage yard and an upstream side of the second temperature raising device in the temperature raising line.

5. The temperature raising device according to claim 3, further comprising a fourth transportation device that is configured to be capable of moving the cast piece between a storage yard for storing the cast piece and the upstream side of the second temperature raising device in the temperature raising line, wherein an downstream side of the second strand is connected to the second transportation device.

6. The temperature raising device according to claim 3, further comprising: a controller that is configured to determine whether the cast piece transported from the second strand is transported to either the first temperature raising device or the second temperature raising device on a basis of a temperature of the cast piece transported on the first strand and the second strand and a temperature of the cast piece at a timing of entering the rough rolling mill, and switches a transportation direction of the cast piece.

7. The temperature raising device according to claim 6, further comprising: at least one of a third transportation device that is configured to be capable of moving the cast piece between a storage yard for storing the cast piece and the downstream side of the second temperature raising device in the temperature raising line, and a fourth transportation device that is configured to be capable of moving the cast piece between the storage yard and an upstream side of the second temperature raising device in the temperature raising line, wherein the controller, in a case where a transportation direction of the cast piece transported from the second strand is switched to the rolling line, transports the cast piece stored in the storage yard to the temperature raising line by using the third transportation device or the fourth transportation device.

8. The temperature raising device according to claim 4, further comprising: a second transportation device that is configured to be capable of moving the cast piece between an upstream side of the first temperature raising device in the rolling line and an upstream side of the second temperature raising device in the temperature raising line; and a controller that is configured to transport the cast piece transported from the second strand to the rolling line by using the second transportation device or stop manufacturing the cast piece on the second strand while a temperature of the cast piece transported from the storage yard is raised by the second temperature raising device.

9. The temperature raising device according to claim 4, further comprising: a controller that is configured to stop manufacturing the cast piece on the second strand while a temperature of the cast piece transported from the storage yard is raised by the second temperature raising device.

10. A rolling facility comprising: a continuous casting machine; the temperature raising device according to any one of claims 1 to 8; and the rough rolling mill for rolling the cast piece with a temperature raised by the temperature raising device.

11. A method of raising a temperature of the cast piece by the temperature raising device according to any one of claims 1 to 9, the method comprising: raising a temperature of the cast piece transported from the second strand, by induction heating in the temperature raising line, and moving the cast piece with a temperature raised in the temperature raising line from the downstream side of the second temperature raising device in the temperature raising line toward the downstream side of the first temperature raising device in the rolling line.

12. A method of raising a temperature of the cast piece by the temperature raising device according to any one of claims 4, 5, 8, and 9, the method comprising: raising a temperature of the cast piece transported from the storage yard, by induction heating in the temperature raising line, and moving the cast piece with a temperature raised in the temperature raising line from the downstream side of the second temperature raising device in the temperature raising line toward the downstream side of the first temperature raising device in the rolling line.

13. The temperature raising method according to claim 12, wherein the cast piece transported from the storage yard is reciprocated in the temperature raising line to raise a temperature thereof.

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