JP2008254041A - Method of rolling rolled stock - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the productivity of steel products while securing prescribed quality of material of the steel products. <P>SOLUTION: This method includes: a stage where a rolled stock is rolled by reciprocating rolling of a prescribed number N of passes with a second roughing mill in a section where rough rolling is performed in a hot-rolling line; a stage where, after that, the rolled stock is moved to the rear side of third and fourth roughing mills, stood by and the rolled stock is cooled down to a prescribed temperature and a stage where, after that, the cooled rolled stock is once returned to the front side of the third and fourth roughing mills and, after that, rolled with the third and fourth roughing mills. When processing a plurality of rolled stocks continuously, the reciprocating rolling of an even number N1 of the maximum possible passes within the prescribed number N of passes is performed to a succeeding material with the second roughing mill while a preceding material is cooled on the rear side of the third and fourth roughing mills. After that, after starting the rolling of the preceding material with the third and fourth roughing mills, the rest rolling of the succeeding material with the second roughing mill is performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rolling method for rolled material.

  For example, in the hot rolling process of steel materials, a cast slab is heated in a heating furnace, and then rolled as a rolled material in order in a rough rolling mill group and a finishing rolling mill group, and finally wound on a winder. These processes are performed in a series of hot rolling lines, and a plurality of steel materials are continuously conveyed and processed in the hot rolling line.

  Incidentally, a plurality of rough rolling mills are usually arranged side by side in the section where rough rolling of the hot rolling line described above is performed. In the steel material rough rolling process, for example, the steel material is reciprocally rolled in a preceding reverse rolling mill and then rolled in a subsequent rough rolling machine.

  In the above-mentioned hot rolling line, in order to ensure excellent toughness, the temperature of the rolled material may be lowered to a specific temperature before rolling in a rough rolling mill at the latter stage of the rough rolling process. Thus, in the case of lowering the temperature of the rolled material before rolling in the subsequent rough rolling mill, for example, after reciprocating rolling in the previous rough rolling mill, between the preceding rough rolling mill and the subsequent rough rolling mill The rolled material was allowed to stand by for a certain period of time and was naturally cooled. Then, the rolled material was carried into a subsequent rough rolling mill and rolling was resumed.

  However, as described above, when the rolled material is made to wait between the preceding rough rolling mill and the subsequent rough rolling mill during cooling, in order to avoid collision between the preceding and subsequent rolling materials, The reciprocating rolling of the rolled material cannot be started. For this reason, the preceding rolling material was cooled to a specific temperature and waited until it was rolled by a subsequent roughing mill, and reciprocating rolling of the next rolling material was started. As a result, the processing efficiency of the steel material in the above hot rolling line was low, and the productivity was low.

  In addition, Patent Document 1 describes that the next slab is rolled while the previous slab is being cooled. However, it takes a relatively long time for reciprocating rolling, and the previous slab is being cooled. The case where it is difficult to finish the reciprocating rolling of the next slab is not assumed at all, and it cannot cope with such a case.

JP 11-319908 A

  The present invention has been made in view of the above points, and in a rolling process in which a rolled material such as a steel material is reciprocally rolled by a preceding rolling mill, then cooled, and then rolled by a subsequent rolling mill, Its purpose is to improve processing efficiency and productivity.

  According to the present invention for achieving the above object, a rolling material rolling method is performed using a rolling mill group having a former rolling mill and a latter rolling mill in this order on a conveyance path, and the rolling material is pre-rolled. A step of reciprocating rolling for a predetermined number of passes by a mill, and then a step of moving the rolled material to a rear side of the rear-stage rolling mill to stand by to cool the rolled material; In the subsequent rolling mill, and in the continuous processing of a plurality of rolled material, while the preceding material is cooled on the rear side of the latter rolling mill, The subsequent material is subjected to reciprocating rolling of the succeeding material by an even number of maximum possible passes within the predetermined number of passes, and then the rolling of the succeeding material by the preceding rolling mill is started after the rolling by the succeeding rolling mill of the preceding material is started. Characteristic to doIn addition, the former stage rolling mill and the latter stage rolling mill may be configured by a single rolling mill or may be configured by a plurality of rolling mills.

  In the rolling method of the rolled material, a cooling time of the rolled material is determined based on the temperature of the rolled material before the end of the reciprocating rolling of the predetermined number of passes, and based on the cooling time, The maximum possible number of passes for reciprocating rolling may be determined.

  In the rolling method of the rolled material, it is preferable to reduce the rolling speed of the rolled material as much as possible when performing reciprocal rolling with the maximum possible number of passes in the preceding rolling mill.

  Further, in the rolling method of the rolled material, during the final pass rolling from the rear side to the front side of the former rolling mill in reciprocating rolling with the maximum possible number of passes of the subsequent material, the preceding material is moved to the rear of the latter rolling mill. It is preferable to convey from the side to the front side of the latter rolling mill.

  In the rolling material rolling method, it is preferable to increase the maximum possible number of passes of the succeeding material by increasing the rolling speed of the succeeding material in the preceding rolling mill higher than the rolling speed of normal operation.

  According to the present invention, since the reciprocating rolling of the succeeding material can be performed as much as possible during the cooling of the preceding material, the processing efficiency of the rolled material can be improved by effectively using the cooling time. In addition, by performing reciprocating rolling of the succeeding material as early as possible, the rolled material becomes thinner at an early stage and the cooling rate is increased. As a result, since the cooling time after reciprocating rolling is shortened, the processing efficiency of the rolled material can be improved and the productivity of the rolled material can be improved. Therefore, it is possible to improve the productivity of the rolled material while securing the desired material of the rolled material by cooling the rolled material during the rolling process.

  Hereinafter, preferred embodiments of the present invention will be described. Drawing 1 is a mimetic diagram showing the outline of the composition of hot rolling equipment 1 concerning this embodiment.

  The hot rolling facility 1 has, for example, a hot rolling line L as a conveying path in which a plurality of conveying rolls and the like are arranged, and along the hot rolling line L, for example, a heating furnace 10 and a rolling mill (VSB). 11, a rough rolling mill group 12, a cutting machine 13, a finish rolling mill group 14, a cooling facility 15, and a winder 16 are provided in this order. In the hot rolling line L, steel materials as a plurality of rolled materials are continuously conveyed and rolled.

  The heating furnace 10 is a walking beam type continuous heating furnace, for example, and can reheat a cast slab to a temperature necessary for rolling.

  The rolling mill 11 can adjust the width of the rolled material by reducing the side surface of the rolled material with a pair of rolls.

  The rough rolling mill group 12 is of a closed couple type, for example, and has a plurality of, for example, four rough rolling mills. The rough rolling mill group 12 includes, for example, a first rough rolling mill 20 in order from the upstream side, a second rough rolling mill 21 as a former rolling mill, a third rough rolling mill 22 as a subsequent rolling mill, and a fourth rough rolling mill. A rolling mill 23 is provided.

  The second rough rolling mill 21 is a reverse rolling mill, and can reciprocally roll the rolled material in the front-rear direction of the conveyance path. Further, the second rough rolling mill 21 is equipped with a descaling facility, and scale can be removed by spraying water onto the rolled material during rolling.

  On the exit side of the second rough rolling mill 21, for example, a temperature sensor 24 that measures the temperature of the rolled material is provided. The measurement result of the rolling material temperature by the temperature sensor 24 can be output to the control unit 30 described later.

  The 3rd rough rolling mill 22 and the 4th rough rolling mill 23 have a reverse rotation function, and can convey a rolling material in the front-back direction. The third rough rolling mill 22 and the fourth rough rolling mill 23 are arranged close to each other in a tandem manner, and a single rolled material can be rolled simultaneously by the two rolling mills 22 and 23.

  Between the 4th rough rolling mill 23 and the cutting machine 13, the space where the rolling material in the middle of a rough rolling process can wait temporarily is provided. For the cutting machine 13, for example, a drum-type crop shear is used, and the front end portion and the rear end portion of the steel sheet after rough rolling can be cut.

  The finish rolling mill group 14 has a plurality of finish rolling mills, and can roll the steel sheet to a target final product thickness.

  The cooling facility 15 can cool the finish-rolled steel sheet to a predetermined temperature. The winder 16 can wind the cooled steel plate into a coil shape.

  Operations of the transport roll, the rough rolling mill group 12 and the like of the hot rolling facility 1 described above are controlled by the control unit 30. The control part 30 is comprised by the computer provided with CPU, memory, etc., for example, The rolling process in the hot rolling equipment 1 can be implemented by running the program memorize | stored, for example in memory.

  Next, the rolling method of the steel material performed with the hot rolling equipment 1 comprised as mentioned above is demonstrated. In the present embodiment, description will be made by taking as an example a rolling process for producing a steel material (API-X70) having a tensile strength of 600 MPa and having excellent toughness used as a line pipe material.

  First, a basic hot rolling process of each steel material performed in the hot rolling facility 1 will be described.

  First, the cast slab H is carried into the heating furnace 10 shown in FIG. 1 and heated to, for example, 1200 ° C. or higher that can be rolled. Thereafter, the width of the slab H is adjusted in the rolling mill 11 as a rolled material, and then conveyed to the rough rolling mill group 12. FIG. 2 shows a flow of main steps of the rough rolling process performed in the rough rolling mill group 12.

  After carrying into the rough rolling mill group 12, the rolled material H is first rolled by the first rough rolling mill 20. Thereafter, the rolled material H is reciprocally rolled by a second roughing mill 21 for a predetermined number of passes N, for example, an odd number of 7 times (7 passes) as shown in FIG. 3 (step S1 in FIG. 2). In addition, this 7-pass reciprocating rolling is not performed continuously at a time in relation to the preceding and subsequent rolling materials as will be described later, but is performed in two steps. Further, the predetermined number of passes N is the number of passes of rough rolling reciprocating rolling set according to the material required for the steel material. For example, when excellent toughness is required, the number of passes N is one time for accumulation of strain. Set the number of passes to be small by increasing the reduction ratio.

  After the completion of the 7-pass rolling, the temperature of the rolled material H is measured by the temperature sensor 24 on the exit side of the second rough rolling mill 21. The temperature measurement result is output to the control unit 30, for example, and the control unit 30 calculates and sets the cooling time T of the rolled material H (step S2 in FIG. 2). In order for the final steel plate to obtain desired toughness, it is necessary to perform rolling by the third rough rolling machine 22 and the fourth rough rolling machine 23 at a specific temperature, for example, about 900 ° C., and the cooling time T is This is the time it takes for the rolled material H to be naturally cooled to about 900 ° C. For example, when the temperature of the rolled material on the exit side of the second rough rolling mill 21 is about 930 ° C., the cooling time T is about 130 seconds.

  After completion of the 7-pass rolling, the rolled material H passes through the third rough rolling mill 22 and the fourth rough rolling mill 23 as shown in FIG. ) To the standby position P. During this passage, the rolled material H is not rolled by the third rough rolling mill 22 and the fourth rough rolling mill 23.

  On the exit side of the fourth rough rolling mill 23, the rolled material H waits for a certain time. The standby time at this time was obtained by subtracting the reciprocating time of the rolled material H from the exit side of the second rough rolling mill 21 to the standby position P on the exit side of the fourth rough rolling mill 23 from the cooling time T. Become a thing. After waiting for a certain period of time, the rolled material H passes through the third rough rolling mill 22 and the fourth rough rolling mill 23 in the reverse direction again without rolling as shown in FIG. 22 is returned to the entrance side (front side). During the reciprocation of the rolled material H, a cooling time T elapses, and the temperature of the rolled material H is cooled to a desired temperature, for example, about 900 ° C. (step S3 in FIG. 2). Thereafter, the rolled material H passes through the third rough rolling mill 22 and the fourth rough rolling mill 23 in the forward direction as shown in FIG. 6 and is rolled (step S4 in FIG. 2).

  After the rough rolling process in the rough rolling mill group 12 is finished, the steel sheet H is cut at the leading end and the trailing end by the cutting machine 13 and then finish-rolled by the finishing mill group 14. Thereafter, the steel sheet H is cooled by the cooling equipment 15 and finally taken up by the winder 16. Thus, the hot rolling process for each steel material is completed.

  Next, in the rough rolling process of the hot rolling facility 1, the operation of the rolled material (the preceding material and the subsequent material) before and after being continuously conveyed will be described. FIG. 7 is a flowchart of main steps in the rough rolling treatment of the rolled material before and after. FIG. 8 shows a time chart of the position and operation of the rolled material before and after the rough rolling process.

  While the preceding preceding material H1 is being rough-rolled as described above, the subsequent succeeding material H2 is conveyed to the roughing mill group 12. As shown in FIGS. 9 and 8, for example, the succeeding material H <b> 2 is obtained after the preceding material H <b> 1 finishes rolling the seven passes with the predetermined number of passes N by the second rough rolling mill 21. It is conveyed to the entry side.

  For example, when the temperature of the preceding material H1 is measured as described above on the exit side of the second rough rolling mill 21 and the cooling time T of the preceding material H1 is set, the control unit 30 sets the cooling time T based on the cooling time T. The maximum possible number of passes N1 for reciprocating rolling of the succeeding material H2 in the second rough rolling mill 21 is set (step S0 in FIG. 7). The maximum possible number of passes N1 of this reciprocating rolling is, for example, an even number of times so that this rolling is finally finished on the entry side of the second rough rolling mill 21, and the maximum number that can be generated within the cooling time T of the preceding material H1. Set to The maximum possible number of passes N1 is the number of rough rolling passes of the succeeding material H2 that can be performed during the cooling waiting time of the preceding material H1, and the rolling speed of the second roughing mill 21 and the rolling length of the succeeding material H2 It is set by comparing the integrated value of the rolling time for each pass obtained by the product of the length and the cooling time T of the preceding material H1. Further, in order to avoid collision between the preceding material H1 and the following material H2 that are fed back at the end of the cooling waiting, the number of passes N1 is an even number. In the present embodiment, the total predetermined number of passes N of the reciprocating rolling in the second rough rolling mill 21 is 7 times, so the maximum possible number of passes N1 is an even number of times less than 6 times and 4 times. It is set to one of two times.

  Thereafter, when the preceding material H1 moves to the standby position P on the exit side of the fourth roughing mill 23 as shown in FIGS. 10 and 8, the succeeding material H2 is allowed to pass through the second roughing mill 21 to the maximum possible number of passes. N1, for example, four times (four passes) reciprocating rolling (step S1a in FIG. 7). And as shown in FIG.11 and FIG.8, when the succeeding material H2 moves to the entrance side of the 2nd rough rolling mill 21 in the last 4th pass, the preceding material H1 becomes the 3rd rough rolling mill 22. And the fourth roughing mill 23 passes in the reverse direction without rolling, and is returned to the entry side of the third roughing mill 22. Thereafter, as shown in FIGS. 12 and 8, the preceding material H <b> 1 is conveyed in the forward direction and passed through the third rough rolling mill 22 and the fourth rough rolling mill 23 and rolled. Along with this, the subsequent material H2 is subjected to reciprocal rolling for the remaining number of passes N2 (N2 = N−N1) in the second roughing mill 21 (step S1b in FIG. 7). In the present embodiment, since the total predetermined number of passes N is 7, the number of remaining passes N2 of the succeeding material H2 is 3 at this time. Thus, the reciprocating rolling of 7 passes, which is the predetermined number of passes N of the succeeding material H2, is completed.

  Thereafter, the temperature of the following material H2 is measured by the temperature sensor 24 in the same manner as the preceding material H1, and the cooling time T of the following material H2 is determined based on the temperature. Further, based on the cooling time T2, the maximum possible number of passes N1 in the second rough rolling mill 21 of the next succeeding material H3 is set. Then, as shown in FIGS. 13 and 8, the succeeding material H2 moves to the standby position P on the exit side of the fourth rough rolling machine 23 and waits, and during that time, the maximum possible path of the next succeeding material H3. A number N1 (for example, 4 passes) of reciprocating rolling is performed. Thereafter, the trailing material H <b> 2 is returned to the entry side of the third rough rolling mill 22, and then conveyed in the forward direction, and rolled by the third rough rolling mill 22 and the fourth rough rolling mill 23. Thereafter, the next succeeding material H3 is subjected to the remaining three passes of reciprocating rolling in the second roughing mill 21.

  The above steps are repeated, and a plurality of rolled materials are continuously processed.

  According to the above embodiment, during the cooling period of the leading material H1, the second roughing mill 21 reciprocally rolls the trailing material H2 with the maximum possible number of passes N1, and then the third rough rolling of the leading material H1. After the rolling by the machine 22 and the fourth rough rolling machine 23 is started, the remaining reciprocating rolling of the succeeding material H2 is performed. Thereby, the cooling time T during the rough rolling process of the preceding material H1 can be effectively used to perform the reciprocating rolling of the succeeding material H2, and the processing efficiency of the rolled material can be improved. In addition, since the reciprocating rolling of the succeeding material H2 is performed as early as possible, the rolled material becomes thinner at an early stage and the cooling rate is increased. As a result, since the cooling time after reciprocating rolling is shortened, the processing efficiency of the rolled material can be improved and the productivity can be improved.

  In the above embodiment, the temperature sensor 24 measures the temperature of the preceding material H1 on the delivery side of the second rough rolling mill 21, and based on the temperature, the cooling time T of the preceding material H1 is set, and the cooling is performed. Since the maximum possible number of passes N1 for reciprocating rolling of the succeeding material H2 is set based on the time T, the cooling time corresponding to the temperature of each rolled material and the maximum reciprocating rolling of the next rolled material corresponding to the cooling time. The number of possible paths can be set. Therefore, it is possible to raise the productivity to the maximum while appropriately cooling each rolled material that is continuously processed to secure the material. In the present embodiment, the cooling time T is set based on the temperature on the exit side of the second rough rolling mill 21, but the temperature of the rolling material in the previous stage, for example, the exit side of the heating furnace 10 The cooling time may be set based on the temperature. Further, it is not always necessary to measure the temperature of the rolled material with a temperature sensor, and the cooling time T may be set from a temperature theoretically derived from the heating condition of the heating furnace 10, for example.

  Moreover, in the above embodiment, when performing reciprocating rolling with the maximum possible number of passes N1 of the rolled material by the second rough rolling mill 21, the rolling speed of the rolled material may be reduced as much as possible. For example, when the maximum possible number of passes N1 of the succeeding material H2 is set from the cooling time T of the preceding material H1, and when the reciprocating rolling of the succeeding material H2 of the maximum possible number of passes N1 is performed, the time becomes longer than the cooling time T There is. In other words, N1 plus two passes that are an even number cannot be made, but the N1 pass has time remaining. In such a case, reciprocating rolling is performed at a rolling speed of the rolled material lower than that during normal operation so that the cooling time T is not exceeded. By doing so, more water for descaling is applied to the rolled material in the second rough rolling mill 21. Moreover, a rolling material will be long indirectly to a low-temperature conveyance roll. For this reason, the rolling material temperature at the end of reciprocating rolling is lower than usual, and the cooling time T of the rolling material can be shortened. As a result, since the total processing time of the rolled material is shortened, the productivity of the steel material can be improved. In addition, since the interval between the first reciprocating rolling and the subsequent reciprocating rolling of the succeeding material H2 is shortened, the recovery of the strain introduced in the first reciprocating rolling can be suppressed, and the strain of the rolled material caused by the reciprocating rolling can be suppressed. Can be effectively accumulated, and finally a steel material with excellent toughness can be efficiently produced.

  In the above embodiment, the preceding material H1 is conveyed from the rear side to the front side of the third and fourth roughing mills simultaneously with the final pass of the reciprocating rolling with the maximum possible number N1 of the succeeding material H2. May be. In such a case, for example, as shown in FIG. 14, the preceding material H1 is conveyed from the rear side to the front side of the third and fourth roughing mills 22, 23 simultaneously with the fourth pass of the succeeding material H2. By doing this, the reciprocating rolling of the succeeding material H2 can be performed until immediately before the cooling time T of the preceding material H1 is finished, and therefore the maximum possible number of passes N1 of the succeeding material H2 can be increased to the maximum. The processing efficiency of the rolled material can be further improved. Also in this case, since the interval between the first reciprocating rolling and the subsequent reciprocating rolling of the succeeding material H2 can be shortened, the strain of the rolled material caused by the reciprocating rolling is effectively accumulated, and finally the toughness is excellent. Steel can be efficiently manufactured.

  Furthermore, in the above embodiment, if the maximum possible number of passes N1 of the rolled material can be increased by increasing the rolling speed of the rolled material in the second roughing mill 21 higher than the rolling speed of the normal operation, the rolling is performed. The rolling speed of the material may be increased. For example, in the above-described embodiment, the maximum possible number of passes N1 of the succeeding material H2 is four times, but by increasing the rolling speed in the second rough rolling mill 21, for example, six passes can be performed. In some cases, the rolling speed is increased above the rolling speed during normal operation. By doing so, the maximum possible number of passes N1 for reciprocating rolling of the second rough rolling mill 21 is increased, and the remaining number of passes N2 is decreased accordingly, so that the subsequent reciprocating rolling of the succeeding material H3 is started earlier. be able to. Thereby, the processing efficiency of a rolling material can be improved. Further, since the rolled material can be thinned at an earlier stage by increasing the maximum possible number of passes N1, the cooling rate of the rolled material is increased and the cooling time T can be shortened. This also improves the processing efficiency of the rolled material.

  The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, but the present invention is not limited to such examples. It will be apparent to those skilled in the art that various changes or modifications can be made within the scope of the ideas described in the claims, and these are naturally within the technical scope of the present invention. It is understood that it belongs. For example, the configuration of the hot rolling line L in the present embodiment may be another configuration.

  The present invention is useful for improving the productivity of a steel material while securing a predetermined material of the steel material.

It is a schematic diagram which shows the outline of a structure of a hot rolling facility. It is a flowchart which shows the main processes of a hot rolling process. It is explanatory drawing which shows a mode that a rolling material is reciprocally rolled in a 2nd rough rolling mill. It is explanatory drawing which shows a mode that a rolling material is made to wait at the standby position of the back of a 4th rough rolling mill. It is explanatory drawing which shows a mode that the cooled rolled material was returned to the front side of the 3rd rough rolling mill. It is explanatory drawing which shows a mode that a rolling material is rolled with the 3rd and 4th rough rolling mill. It is a flowchart which shows the main processes in the rough rolling process of the continuous rolling material. It is explanatory drawing which shows the position and operation | movement of the continuous rolling material in a rough rolling process. It is explanatory drawing which shows a mode that a succeeding material is conveyed by the entrance side of a 2nd rough rolling mill, when a preceding material complete | finishes reciprocating rolling in a 2nd rough rolling mill. It is explanatory drawing which shows a mode that a succeeding material is reciprocating-rolled in a 2nd roughing mill, when a preceding material waits in a stand-by position. It is explanatory drawing which shows a mode that a preceding material is returned to the entrance side of a 3rd rough rolling machine, when the reciprocating rolling of the maximum possible number of passes of a succeeding material is complete | finished in a 2nd rough rolling mill. It is explanatory drawing which shows a mode that the rolling of a preceding material is started in the 3rd and 4th rough rolling mill, and the remaining reciprocating rolling of a succeeding material is performed in a 2nd rough rolling mill. It is explanatory drawing which shows a mode that the following succeeding material is reciprocating-rolled in a 2nd roughing mill, when a succeeding material waits in a stand-by position. Explanatory drawing which shows a mode that a preceding material is conveyed in the entrance side of the 3rd and 4th rough rolling mill during the last pass rolling of the reciprocating rolling by the maximum possible number of passes of the succeeding material in the 2nd rough rolling mill. It is.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hot rolling equipment 12 Rough rolling mill group 21 2nd rough rolling mill 22 3rd rough rolling mill 23 4th rough rolling mill 24 Temperature sensor L Hot rolling line P Standby position H Rolled material

Claims (5)

It is a rolling method of a rolled material performed using a rolling mill group having a former rolling mill and a latter rolling mill in this order on a conveyance path,
A step of reciprocating a predetermined number of passes of the rolled material by a preceding rolling mill;
Then, the step of moving the rolled material to the rear side of the subsequent rolling mill and waiting, and cooling the rolled material,
Thereafter, the cooled rolled material is once returned to the front side of the latter rolling mill and then rolled by the latter rolling mill,
When continuously processing a plurality of rolled materials, while the preceding material is cooled on the rear side of the latter rolling mill, the number of maximum possible passes within the predetermined number of passes of the succeeding material by the former rolling mill A method for rolling a rolled material, comprising performing reciprocating rolling, and thereafter starting rolling by a subsequent rolling mill of the preceding material, and then performing the remaining rolling of the succeeding material by a preceding rolling mill. Based on the temperature of the rolled material before the end of reciprocating rolling of the predetermined number of passes, a cooling time of the rolled material is determined, and based on the cooling time, the maximum possible number of passes of reciprocating rolling of the next rolled material is The method for rolling a rolled material according to claim 1, wherein the rolling method is defined. The method for rolling a rolled material according to claim 1 or 2, wherein the rolling speed of the rolled material is reduced as much as possible when performing reciprocating rolling with the maximum possible number of passes in the former rolling mill. During the final pass rolling from the rear side to the front side of the former rolling mill in reciprocating rolling with the maximum possible number of passes of the subsequent material, the preceding material is conveyed from the rear side of the rear rolling mill to the front side of the rear rolling mill. The rolling method of the rolled material according to any one of claims 1 to 3, wherein the rolling method is performed. The rolling speed of the succeeding material in the preceding rolling mill is increased from the rolling speed of normal operation to increase the maximum possible number of passes of the succeeding material. Rolling method of the rolled material.

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