JP2013052406A - Tandem finishing mill, operation control method for the same, and apparatus and method for manufacturing hot-rolled steel sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation control method for a tandem finishing mill that can improve the yield of ultrafine grained steel.SOLUTION: The operation control method for the tandem finishing mill includes starting a change of a plate thickness target value of an n-th stand (n is all integers of m or more and N or less) simultaneously with the arrival of a plate thickness change point of a rolled material at an N-th stand, obtaining, during the change of the plate thickness target value of the n-th stand at least, a first rolling reduction position correction amount for making the outlet side plate thickness of the n-th stand coincident with the plate thickness target value, obtaining the plate thickness deviation of an (n-1)th stand in the n-th stand of n>m, obtaining a second rolling reduction position correction amount for preventing the outlet side plate thickness of the n-th stand of n>m from being influenced by the plate thickness deviation, correcting the rolling reduction position of an m-th stand every moment by the first rolling reduction position correction amount, and correcting the rolling reduction position of the n-th stand of n>m every moment by an added value of the first rolling reduction position correction amount and the second rolling reduction position correction amount.

Description

  The present invention relates to a tandem finish rolling mill, an operation control method thereof, a hot-rolled steel plate manufacturing apparatus, and a hot-rolled steel plate manufacturing method. The present invention particularly relates to a tandem finish rolling mill that changes the thickness and / or non-use of rolling lubricant during rolling of one rough bar in a tandem finish rolling mill of a hot rolling line, and its The present invention relates to an operation control method, an apparatus for manufacturing a hot-rolled steel sheet having the tandem finish rolling mill, and a method for manufacturing a hot-rolled steel sheet using the operation control method of the tandem finish rolling mill.

  In the hot rolling step, first, a slab is rolled by a roughing mill to generate a rough bar, and then the rough bar is rolled to a target plate thickness by a tandem finish rolling mill having a plurality of rolling mills (stands). The operation of each stand in finish rolling is determined so that the thickness, width, etc. of the material to be rolled on the final stand exit side satisfy the target condition. The operating condition of each stand is called a draft schedule (pass schedule), and greatly affects the quality and productivity of the product. Therefore, it is required to determine an appropriate draft schedule according to the product.

  The draft schedule of a tandem finish rolling mill is usually a stand that is closer to the final product (on the downstream side in the direction of movement of the material to be rolled) in order to reduce the rough surface of the work roll surface and keep the surface properties of the product better. The rolling load is determined to be light. Here, even if the reduction ratio of the first stage (upstream side in the moving direction of the material to be rolled) stand and the second stage stand is set to be the same, the latter stage stand that rolls the material to be rolled with a small thickness requires a large rolling load. There are rolling characteristics. Therefore, in the normal draft schedule, the rolling reduction is smaller as the latter stage stand.

  On the other hand, steel materials used for automobiles and structural materials are required to have excellent mechanical properties such as strength, workability, and toughness. To improve these mechanical properties comprehensively, It is effective to refine the grains. Further, if the crystal grains are refined, it is possible to produce a high-strength hot-rolled steel sheet having excellent mechanical properties even if the addition amount of the alloy element is reduced.

  As a method for refining the crystal grains of hot-rolled steel sheets, particularly in the latter stage of hot finish rolling, high pressure rolling (finish rolling with a higher reduction ratio of the latter stage stand) is performed to refine the austenite grains and within the grains. There is known a method for accumulating rolling strain and quenching immediately after finish rolling to refine the ferrite grains obtained. In order to produce a hot rolled steel sheet (hereinafter referred to as “ultrafine grain steel”) having ultrafine crystal grains (for example, crystal grains having an average grain diameter of 2 μm or less; the same applies hereinafter) by this method. Therefore, it is necessary to increase the reduction ratio of the rear stage stand of the tandem finish rolling mill in the hot rolling line as compared with the conventional technique. Therefore, in order to manufacture fine-grained steel, it is necessary to determine a draft schedule different from the conventional one and to control the operation of the tandem finish rolling mill in a form different from the conventional one.

  However, if the reduction ratio of the rear stand is increased, the load on the rear stand (rolling load, rolling torque, etc.) increases, and rolling of unsteady parts such as the leading plate at the tip and the tail end of the tail end becomes difficult. At the tail end, it may be necessary to lower the rolling reduction of the rear stage stand and roll it thicker than the original thickness target value of the product.

  In addition, it is effective to use a rolling lubricant to keep the load on the rear stand within the upper limit of the equipment and to improve the surface properties of the material to be rolled, but the work roll and the material to be rolled can be obtained by using the rolling lubricant. When the coefficient of friction between the roll and the roll decreases, the workability of the material to be rolled into the work roll deteriorates. Therefore, the rolling lubricant is not used when the leading edge is passed. You need to start using.

  As a technique for changing the plate thickness required for the production of such ultrafine-grained steel or changing the non-use of rolling lubricant, for example, in Patent Document 1, when the plate thickness change point reaches a certain stand At the same time, the plate thickness target value of the stand is changed at a constant rate, and the operation of correcting the reduction position of the stand so as to match the plate thickness target value is performed from the most upstream stand whose thickness is to be changed to the final stand. Until now, the technology to repeat in order is disclosed.

Japanese Patent Application No. 2010-74195

  According to the technique disclosed in Patent Document 1, it is possible to suppress the tension fluctuation during the change of the plate thickness and the tension fluctuation during the change of non-use of the rolling lubricant. Since it is repeated in order from the most upstream stand to the last stand, the time until all changes are completed becomes longer. As a result, a portion where the plate thickness deviates from a desired value or a portion where the surface property of the material to be rolled is bad becomes long, and such a portion cannot be made into a product, so that the problem of poor yield remains.

  Accordingly, the present invention provides a tandem finish rolling mill capable of improving the yield when changing the plate thickness required for producing ultrafine-grained steel or changing the non-use of rolling lubricant. It is an object of the present invention to provide an operation control method thereof, a hot-rolled steel plate manufacturing apparatus having the tandem finish rolling mill, and a hot-rolled steel plate manufacturing method using the tandem finish rolling mill.

  The present invention will be described below. In order to facilitate understanding of the present invention, reference numerals in the accompanying drawings are appended in parentheses, but the present invention is not limited to the illustrated embodiments.

  In the first aspect of the present invention, one rolled material (8) is transferred to a tandem finish rolling mill (10) provided with N stands (N is an integer of 2 or more) (1, 2, ..., 7). Tandem finish rolling mill (10) in which the thickness target value in the Nth stand (7) is changed from the mth stand (m is an integer of 1 to N-1) (5) during rolling At the same time that the sheet thickness change point of the material to be rolled reaches the Nth stand (7) (n is an integer from m to N) (5, 6, 7). ) Is started, and the thickness of the material to be rolled on the exit side of the nth stand is determined as the thickness target at least in the time period from the start of change of the thickness target value of the nth stand to the end of change. The first reduction position correction amount of the nth stand (5, 6, 7) to be matched with the value is obtained, and n In the nth stand (6, 7) of m, the thickness of the material to be rolled on the exit side of the n-1 stand (5, 6) and the thickness target before the start of change on the exit side of the n-1 stand The thickness deviation which is a difference from the value is obtained, and the influence of the thickness deviation of the (n-1) th stand is prevented from appearing in the thickness of the material to be rolled on the exit side of the nth stand where n> m. The second reduction position correction amount of the nth stand (6, 7) is obtained, the reduction position of the mth stand (5) is corrected momentarily by the first reduction position correction amount, and the nth stand of n> m The operation control method for a tandem finish rolling mill is characterized in that the rolling position of (6, 7) is corrected momentarily by an addition value of a first rolling position correction amount and a second rolling position correction amount.

  Here, in the first aspect of the present invention and the other aspects of the present invention described below (hereinafter, these may be collectively referred to as “the present invention”), the “Nth stand (7)” means The final stand of the tandem rolling mill (10), that is, the stand (7) of the tandem rolling mill arranged at the downstream end in the moving direction of the material (8) to be rolled by the tandem rolling mill (10).

  According to a second aspect of the present invention, a single rolled material (8) is obtained by a tandem finish rolling mill (10) having N stands (N is an integer of 2 or more) (1, 2, ..., 7). Tandem finish rolling mill in which rolling lubricant is not used in the Nth stand (7) from the mth stand (m is an integer of 1 to N-1) (5) during rolling. The method of controlling the operation of (10), wherein the non-use of the rolling lubricant of the n-th stand (n is an integer from m to N) (5, 6, 7) is changed at the same timing. The exit side of the nth stand at least in the time zone required for the change in the coefficient of friction between the work rolls (5a, 6a, 7a) and the material to be rolled (8) due to the non-use of the rolling lubricant of the nth stand N-th stand (5, 6, ) In the nth stand (6, 7) where n> m, and the thickness of the material to be rolled on the exit side of the n-1 stand (5, 6) The thickness deviation, which is the difference from the thickness target value on the exit side of the n-1 stand, is obtained, and the influence of the thickness deviation of the n-1 stand is that of the material to be rolled on the exit side of the nth stand where n> m. The second reduction position correction amount of the nth stand (6, 7) of n> m so as not to appear in the plate thickness is obtained, and the reduction position of the mth stand (5) is sometimes changed by the first reduction position correction amount. It is corrected every moment, and the reduction position of the nth stand (6, 7) with n> m is corrected every moment by an addition value of the first reduction position correction amount and the second reduction position correction amount. This is an operation control method for a tandem finish rolling mill.

  In a third aspect of the present invention, one rolled material (8) is obtained by a tandem finish rolling mill (10) provided with N stands (N is an integer of 2 or more) (1, 2, ..., 7). During rolling, the mth stand (m is an integer of 1 to N-1) (5) to the Nth stand (7) thickness target value and the non-use of rolling lubricant are changed. The method of controlling the operation of the tandem finish rolling mill (10), wherein the thickness change point of the material to be rolled reaches the Nth stand (7) and at the same time the nth stand (where n is not less than m and not more than N). Integer) (5, 6, 7) The thickness target value of (5, 6, 7) and the change of non-use of rolling lubricant are started, and at least in the time zone from the start of change of the thickness value of the nth stand to the end of change The nth stand (5) which matches the plate thickness of the material to be rolled on the exit side of the n stand with the plate thickness target value. 6 and 7) and the thickness of the material to be rolled on the exit side of the n-1th stand (5, 6) in the nth stand (6, 7) where n> m. And a thickness deviation which is a difference between the thickness target value before the start of change on the exit side of the n-1th stand, and the influence of the thickness deviation of the n-1th stand is n> m The second rolling position correction amount of the n> mth stand (6, 7) not to appear in the thickness of the material to be rolled on the exit side is obtained, and the rolling position of the mth stand (5) is set to the first. The rolling position correction amount is corrected every moment, and the rolling position of the nth stand (6, 7) with n> m is corrected momentarily by the sum of the first rolling position correction amount and the second rolling position correction amount. This is a method for controlling the operation of a tandem finish rolling mill.

  In the third aspect of the present invention, the time from the start of change of the plate thickness target value of the n-th stand (5, 6, 7) to the end of change is a work roll generated by change of non-use of rolling lubricant ( 5a, 6a, 7a) and the time required for the change of the friction coefficient between the material to be rolled (8) are preferably set to be longer than the time required.

  The fourth aspect of the present invention uses a tandem finish rolling mill (10) controlled by the operation control method of the tandem finish rolling mill according to any one of the first aspect of the present invention to the third aspect of the present invention. A method for producing a hot-rolled steel sheet, comprising the step of finish rolling the steel sheet (8).

  According to a fifth aspect of the present invention, one rolled material (8) is provided by a tandem finish rolling mill (10) including N (N is an integer of 2 or more) stands (1, 2, ..., 7). Tandem finish rolling mill (10) in which the thickness target value in the Nth stand (7) is changed from the mth stand (m is an integer of 1 to N-1) (5) during rolling And the plate | board thickness target value of nth stand (n is all integers below m and N) (5, 6, 7) at the same time the plate | board thickness change point of a to-be-rolled material reaches | attains Nth stand (7) The thickness of the material to be rolled on the exit side of the nth stand matches the thickness target value at least in the time zone from the start of change of the target thickness value of the nth stand to the end of change. From the mth stand to the Nth stand (5, 6, 7) to obtain the first reduction position correction amount of the stand Plate thickness control means (15, 16, 17) and the thickness of the material to be rolled on the exit side of the n-1 stand (5, 6) of n> m and before the start of the change of the n-1 stand The second plate thickness of the (m + 1) -th stand to the N-th stand (6, 7) for obtaining the second reduction position correction amount of the n-th stand (6, 7) of n> m based on the difference from the plate thickness target value. A control means (26, 27), a reduction position control means (5c) of the m-th stand for correcting the reduction position momentarily by the first reduction position correction amount obtained by the first plate thickness control means, The m + 1th stand for correcting the rolling position from moment to moment by the added value of the first rolling position correction amount obtained by the plate thickness control means and the second rolling position correction amount obtained by the second thickness control means. To the N-th stand reduction position control means (6c, 7c), A finishing mill.

  According to a sixth aspect of the present invention, one rolled material (8) is obtained by a tandem finish rolling mill (10) provided with N stands (N is an integer of 2 or more) (1, 2, ..., 7). Tandem finish rolling mill in which rolling lubricant is not used in the Nth stand (7) from the mth stand (m is an integer of 1 to N-1) (5) during rolling. A lubricant supply means (5e, 6e, 7e) for changing the non-use of the rolling lubricant of the n-th stand (n is an integer from m to N) (5, 6, 7); At least in the time zone required for the change of the coefficient of friction between the work rolls (5a, 6a, 7a) and the material to be rolled (8) due to the non-use of the rolling lubricant of the nth stand, on the exit side of the nth stand The first rolling position correction of the nth stand that matches the thickness of the material to be rolled with the target thickness. The first plate thickness control means (15, 16, 17) of the Nth stand (5, 6, 7) and the n-1th stand (5, 6) satisfying n> m Based on the difference between the plate thickness of the material to be rolled on the side and the plate thickness target value on the exit side of the (n-1) th stand, the second reduction position correction amount of the nth stand (6, 7) with n> m is set. The second plate thickness control means (26, 27) of the (m + 1) th stand to the Nth stand (6, 7) to be obtained and the first reduction position correction amount obtained by the first plate thickness control means are set to the reduction position. The reduction position control means (5c) of the m-th stand that is corrected every moment, the first reduction position correction amount obtained by the first plate thickness control means, and the second value obtained by the second plate thickness control means. The crush position of the m + 1th stand to the Nth stand, which corrects the crushing position from moment to moment by the addition value of the crushing position correction amount. And control means (6c, 7c), characterized by having a a tandem finishing mill.

  In a seventh aspect of the present invention, one rolled material (8) is provided by a tandem finish rolling mill (10) including N stands (N is an integer of 2 or more) (1, 2, ..., 7). During rolling, the mth stand (m is an integer of 1 to N-1) (5) to the Nth stand (7) thickness target value and the non-use of rolling lubricant are changed. The tandem finish rolling mill (10), wherein the thickness change point of the material to be rolled reaches the Nth stand (7) and at the same time the nth stand (n is an integer from m to N) (5, 6 7) Lubricant supply means (5e, 6e, 7e) for changing the use / non-use of the rolling lubricant, and the nth stand (at the same time that the sheet thickness change point of the material to be rolled reaches the Nth stand (7)). 5. Change of thickness target value of 5, 6, 7) is started, and at least change of thickness target value of nth stand is started During the time period until the end, the mth stand to the Nth stand for obtaining the first reduction position correction amount of the nth stand that matches the thickness of the material to be rolled on the exit side of the nth stand with the thickness target value ( 5, 6, 7) The first thickness control means (15, 16, 17) and the thickness of the material to be rolled on the exit side of the n-1th stand (5, 6) where n> m From the (m + 1) th stand to the Nth stand (6, 7) for obtaining the second reduction position correction amount of the nth stand (6, 7) based on the difference from the plate thickness target value before starting the change on the exit side of the n-1 stand. 7) The second plate thickness control means (26, 27) of 7) and the reduction position control of the m-th stand that corrects the reduction position every moment by the first reduction position correction amount obtained by the first thickness control means. Means (5c), the first reduction position correction amount obtained by the first plate thickness control means and the second The m + 1 stand to the Nth stand reduction position control means (6c, 7c) for correcting the reduction position every moment by an addition value with the second reduction position correction amount obtained by the plate thickness control means. This is a tandem finish rolling mill.

  In the seventh aspect of the present invention, the time from the start of change of the thickness target value of the n-th stand (5, 6, 7) to the end of change is a work roll generated by change in non-use of rolling lubricant ( 5a, 6a, 7a) and the time required for the change of the friction coefficient between the material to be rolled (8) are preferably set to be longer than the time required.

  An eighth aspect of the present invention is an apparatus for producing a hot-rolled steel sheet, comprising the tandem finish rolling mill (10) according to any one of the fifth aspect to the seventh aspect of the present invention. (100).

  In the first aspect of the present invention, the thickness target values of all the stands (5, 6, 7) whose thickness target values are to be changed are changed at the same time. The time to do is shorter than the conventional method. Moreover, the influence which the plate | board thickness change of the change process of an upstream stand (5,6) acts as an entrance side board | plate thickness fluctuation | variation disturbance of a downstream stand (6,7) suppresses by the 2nd reduction position correction amount. Therefore, according to the first aspect of the present invention, the plate thickness on the final stand exit side coincides with the target value changed when the plate thickness required for producing ultrafine-grained steel is changed. Therefore, it is possible to provide an operation control method for a tandem finish rolling mill that can shorten the time required to improve the yield and improve the yield.

  In the second aspect of the present invention, since the use / non-use of all the stands (5, 6, 7) subject to the change of the non-use of the rolling lubricant is changed at the same time, the work of all the change target stands The time until the friction coefficient change between the rolls (5a, 6a, 7a) and the material to be rolled (8) is completed is shorter than that in the conventional method. Further, the influence of the change in the plate thickness in the process of changing the friction coefficient of the upstream stand (5, 6) acting as disturbance on the inlet side plate thickness fluctuation of the downstream stand (6, 7) is suppressed by the second reduction position correction amount. Therefore, according to the second aspect of the present invention, the thickness deviation on the exit side of the final stand is small even when changing the use or non-use of the rolling lubricant that is necessary when manufacturing ultrafine-grained steel. Thus, it is possible to provide an operation control method for a tandem finish rolling mill that does not cause a deviation in thickness tolerance and can improve the yield.

  In the third aspect of the present invention, the change of the thickness target value and the rolling lubrication of all the stands (5, 6, 7) that are the targets of the change of the thickness target value and the change of non-use of the rolling lubricant. Since the non-use change of the agent is performed at the same time, the time until all the change target stands are changed is shorter than the conventional method. Moreover, the influence which the plate | board thickness change of the change process of an upstream stand (5,6) acts as an entrance side board | plate thickness fluctuation | variation disturbance of a downstream stand (6,7) suppresses by the 2nd reduction position correction amount. Therefore, according to the third aspect of the present invention, when changing the plate thickness and the non-use of the rolling lubricant that are required when producing ultrafine-grained steel, It is possible to provide an operation control method for a tandem finish rolling mill capable of reducing the time until the plate thickness matches the changed target value and improving the yield.

  Further, in the third aspect of the present invention, the time from the start of change of the plate thickness target value of the stand (5, 6, 7) to be changed of the plate thickness target value to the end of change is expressed as rolling lubricant. It becomes easy to improve a yield by making it more than the time required for the change of the friction coefficient between the work rolls (5a, 6a, 7a) and the material to be rolled (8) caused by the change of use / non-use.

  The fourth aspect of the present invention uses a tandem finish rolling mill (10) controlled by the operation control method of the tandem finish rolling mill according to any one of the first aspect of the present invention to the third aspect of the present invention. And rolling the steel plate (8). Therefore, according to the 4th aspect of this invention, the manufacturing method of a hot-rolled steel plate which can improve a yield and can manufacture ultra-fine grain steel can be provided.

  In the fifth aspect of the present invention, the thickness target values of all the stands (5, 6, 7) whose thickness target values are to be changed are changed at the same time. The time to do is shorter than the conventional method. Moreover, the influence which the plate | board thickness change of the change process of an upstream stand (5,6) acts as an entrance side board | plate thickness fluctuation | variation disturbance of a downstream stand (6,7) suppresses by the 2nd reduction position correction amount. Therefore, according to the fifth aspect of the present invention, the plate thickness on the final stand exit side coincides with the target value changed when the plate thickness required for manufacturing the ultrafine-grained steel is changed. It is possible to provide a tandem finish rolling mill (10) capable of shortening the time required for improving the yield and improving the yield.

  In the sixth aspect of the present invention, since the use / nonuse of all the stands (5, 6, 7) subject to change of non-use of the rolling lubricant is changed at the same time, the work of all the change target stands The time until the friction coefficient change between the rolls (5a, 6a, 7a) and the material to be rolled (8) is completed is shorter than that in the conventional method. Further, the influence of the change in the plate thickness in the process of changing the friction coefficient of the upstream stand (5, 6) acting as the fluctuation fluctuation on the downstream side of the downstream stand is suppressed by the second reduction position correction amount. Therefore, according to the sixth aspect of the present invention, the thickness deviation on the exit side of the final stand is small even when changing the use or non-use of the rolling lubricant necessary for producing ultrafine-grained steel. As a result, it is possible to provide a tandem finish rolling mill (10) that is less likely to cause a deviation in thickness tolerance and can improve the yield.

  In the seventh aspect of the present invention, the change of the thickness target value and the rolling lubrication of all the stands (5, 6, 7) subject to the change of the thickness target value and the change of non-use of the rolling lubricant. Since the non-use change of the agent is performed at the same time, the time until all the change target stands are changed is shorter than the conventional method. Moreover, the influence which the plate | board thickness change of the change process of an upstream stand (5,6) acts as an entrance side board | plate thickness fluctuation | variation disturbance of a downstream stand (6,7) suppresses by the 2nd reduction position correction amount. Therefore, according to the seventh aspect of the present invention, when changing the plate thickness and changing the non-use of the rolling lubricant which are necessary when producing ultrafine-grained steel, It is possible to provide a tandem finish rolling mill (10) capable of reducing the time until the plate thickness matches the changed target value and improving the yield.

  In the seventh aspect of the present invention, the time from the start of change of the plate thickness target value of the stand (5, 6, 7) to which the plate thickness target value is changed until the end of change is expressed as rolling lubricant. It becomes easy to improve a yield by making it more than the time required for the change of the friction coefficient between the work rolls (5a, 6a, 7a) and the material to be rolled (8) caused by the change of use / non-use.

  An apparatus (100) for producing a hot-rolled steel sheet according to an eighth aspect of the present invention includes the tandem finish rolling mill (10) according to any one of the fifth aspect to the seventh aspect of the present invention. Yes. Therefore, according to the 8th aspect of this invention, the manufacturing apparatus (100) of a hot-rolled steel plate which can improve a yield and can suppress a tension | tensile_strength fluctuation | variation at the time of manufacture of an ultra fine grain steel can be provided. .

It is a figure which shows the example of the form of the tandem finish rolling mill 10 with which the operation | movement control method of the tandem finish rolling mill of this invention is applied. It is a figure which simplifies and shows the form example of the manufacturing apparatus 100 of the hot-rolled steel plate concerning this invention. It is a graph which shows the rolling state at the time of controlling by the operation | movement control method of the tandem finish rolling mill of this invention. It is a graph which shows the rolling state at the time of controlling by the operation | movement control method of the tandem finish rolling mill of this invention. It is a graph which shows the rolling state at the time of controlling by methods other than this invention. It is a graph which shows the rolling state at the time of controlling by methods other than this invention.

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

  FIG. 1 is a diagram showing a form example of a tandem finish rolling mill 10 to which an operation control method for a tandem finish rolling mill according to the present invention is applied. As shown in FIG. 1, the tandem finish rolling mill 10 has seven stands of a first stand 1, a second stand 2,..., And a seventh stand 7. The material to be rolled 8 (hereinafter sometimes referred to as “steel plate 8”) can be continuously rolled by seven stands up to the stand 7. These seven stands 1 to 7 are respectively a pair of work rolls 1a, 1a to 7a, a pair of backup rolls 1b, 1b to 7b, 7b, a reduction position control device 1c to 7c, and a speed control device 1d to 7d. It has. That is, for example, the first stand 1 includes a pair of work rolls 1a and 1a, a pair of backup rolls 1b and 1b, a reduction position control device 1c, and a speed control device 1d. A pair of work rolls 7a, 7a, a pair of backup rolls 7b, 7b, a reduction position control device 7c, and a speed control device 7d are provided. Moreover, each stand 1-7 is provided with lubricant supply means 1e-7e. Lubricant supply means 1e to 7e are apparatuses for injecting rolling lubricant (for example, rolling lubricant or rolling lubricant aqueous solution) toward work rolls 1a to 7a, respectively. A pipe for supplying and a nozzle for injecting a rolling lubricant toward the work roll are provided. The rolling position control device 1c is a device that adjusts the rolling position of the first stand 1, and thereby the gap between the pair of work rolls 1a and 1a is adjusted, and the thickness of the steel plate 8 is adjusted. The same applies to the reduction position control devices 2c to 7c. The speed control device 1d is a device that operates so that the roll speed of the work rolls 1a and 1a matches the roll speed command value of the work rolls 1a and 1a given from the speed command device 30. And the rotational speed of the backup rolls 1b and 1b is adjusted. The same applies to the speed control devices 2d to 7d.

  The first stand 1 to the seventh stand 7 are provided with first plate thickness control devices 11 to 17 that operate in a feedback manner so that the exit side plate thicknesses of the steel plates 8 in the respective stands 1 to 7 coincide with the target values. The second stand 2 to the seventh stand 7 are second plate thicknesses that operate in a feed-forward manner so that the influence of the variation in the entry side plate thickness of the steel plate 8 in each stand 2 to 7 does not appear in the exit side plate thickness. Control devices 22 to 27 are provided. The time for changing the plate thickness target value by the first plate thickness control devices 11 to 17 is determined by the plate thickness target value change time determination device 28. Further, the tandem finish rolling mill 10 is provided with a timing indicating device 40 having a function of tracking where the point defined on the steel plate 8 is located on the tandem finish rolling mill 10. Is given to the first plate thickness control devices 11 to 17, the second plate thickness control devices 22 to 27, the speed command device 30, and the lubricant supply means 1e to 7e based on the tracking information obtained using It is configured as follows.

  In the first stand 1, the first plate thickness control device 11 gives a first roll-down position correction amount that matches the outlet side plate thickness of the first stand 1 to the target value. 1 is adjusted, and the plate thickness (outside plate thickness) of the steel plate 8 in the first stand 1 is adjusted. In the second stand 2, the first plate thickness control device 12 gives a first roll-down position correction amount that matches the outlet plate thickness of the second stand 2 to the target value, and the second plate thickness. The control device 22 gives a second reduction position correction amount to the reduction position control device 2c so that the influence of the entry side plate thickness of the second stand 2 does not appear on the exit side plate thickness of the second stand 2, and the reduction position control device 2c. By 2c, the reduction position of the second stand 2 is adjusted by the added value of the first reduction position correction amount and the second reduction position correction amount, and the plate thickness (outside plate thickness) of the steel plate 8 in the second stand 2 is adjusted. Adjusted. The third stand 7 to the seventh stand 7 are the same as the second stand 2.

  Hereinafter, referring to FIG. 1, in the case of N = 7 and m = 5 which is an embodiment of the present invention, the operation control of the present invention starts to change the thickness target value and starts to use the rolling lubricant. The method will be specifically described. The roll speed refers to the rotation speed of the work roll, and in the following description, it is assumed that the plate thickness before and after the draft schedule change and the plate thickness target value change time are determined before the start of rolling. Yes.

The plate thickness target value change time determination device 28 calculates a plate thickness target value change time T common to the fifth stand 5 to the seventh stand 7. If T is too small, the change rate of the plate thickness target value becomes too fast, and due to the delay in following the plate thickness control, the change in the reduction position and the change in the roll speed are mismatched, and the tension fluctuates. If T is too large, it takes a long time to change the plate thickness. Therefore, a portion where the plate thickness does not coincide with the plate thickness target value after the change to be originally obtained becomes long. Therefore, it is desirable to determine the plate thickness target value change time T so as to be minimized within a range in which the follow-up delay of the plate thickness control does not become a problem. For example, if the thickness change amount of the nth stand is Δh _n and the follow delay time of the thickness control with respect to the target thickness value of the nth stand is t _n , the target thickness value is changed at a change rate of Δh _n / T. Since the plate thickness control error when changing is (Δh _n / T) · t _n , the following equation (1) is set so that Δh _n (n = 5 to 7) is equal to or less than a predetermined value α. ) To determine the thickness target value change time T and give it to the first thickness control devices 15 to 17.
T = max Δh _n · t _n / α (1)

  Furthermore, when changing the use / non-use of the rolling lubricant, it is desirable that T be equal to or longer than the time required for changing the friction coefficient by changing the use / non-use of the rolling lubricant.

  The timing indicating device 40 tracks the thickness change point of the steel plate 8 and notifies the speed command device 30 of the timing when the thickness change point reaches the seventh stand 7. The speed command device 30 receives the notification from the timing instruction device 40, and controls to suppress the tension fluctuation caused by the change of the plate thickness target value or the change of non-use of the rolling lubricant (for example, Japanese Patent Application No. 2010-57300). The control method disclosed in FIG. 2 is started, and a roll speed change command for the first stand 1 to the seventh stand 7 is given to the speed control devices 1d to 7d. The speed control devices 1d to 7d adjust the roll speed so that the roll speeds of the stands 1 to 7 coincide with the roll speed change command from the speed command device 30.

Moreover, the timing instruction | indication apparatus 40 notifies the timing to the 1st board thickness control apparatuses 15-17, when the board thickness change point of the steel plate 8 reaches the 7th stand 7. FIG. Upon receiving the notification, the first plate thickness control device 15 of the fifth stand 5 changes the plate thickness change amount Δh ₅ of the fifth stand 5 and the plate thickness target value change time common to the fifth stand 5 to the seventh stand 7. Based on T, a plate thickness target value change rate Δh ₅ / T is determined. Then, the change of the thickness target value of the fifth stand 5 is started at the change rate of Δh ₅ / T so that the thickness (outside thickness) of the steel plate 8 in the fifth stand 5 matches the target thickness value. The first reduction position correction amount ΔS _5a of the fifth stand 5 is obtained and given to the reduction position control device 5c. The change of the thickness target value of the fifth stand 5 ends after the time T has elapsed since the start of the change. Similarly, when the first thickness control device 16 of the sixth stand 6 receives a notification from the timing instruction device 40 that the thickness change point of the steel plate 8 has reached the seventh stand 7, the thickness of the sixth stand 6 is reached. Based on the change amount Δh ₆ and the plate thickness target value change time T, the plate thickness target value change rate Δh ₆ / T is determined. Then, the change of the plate thickness target value of the sixth stand 6 is started at the change rate of Δh ₆ / T so that the plate thickness (exit side plate thickness) of the steel plate 8 in the sixth stand 6 matches the plate thickness target value. The first reduction position correction amount ΔS _6a of the sixth stand 6 is obtained and given to the reduction position control device 6c. The change of the thickness target value of the sixth stand 6 is ended after elapse of time T from the start of the change. Similarly, when the first plate thickness control device 17 of the seventh stand 7 receives a notification from the timing instruction device 40 that the plate thickness change point of the steel plate 8 has reached the seventh stand 7, the plate thickness of the seventh stand 7 is reached. Based on the change amount Δh ₇ and the plate thickness target value change time T, the plate thickness target value change rate Δh ₇ / T is determined. Then, the change of the plate thickness target value of the seventh stand 7 is started at the change rate of Δh ₇ / T so that the plate thickness (exit side plate thickness) of the steel plate 8 in the seventh stand 7 matches the plate thickness target value. The first reduction position correction amount ΔS _7a of the seventh stand 7 is obtained and given to the reduction position control device 7c. The change of the thickness target value of the seventh stand 7 is ended after elapse of time T from the start of the change. In the above description, a specific method for obtaining the first reduction position correction amounts ΔS _5a , ΔS _6a , ΔS _7a for matching the outlet side plate thickness with the plate thickness target value is the same as that of the known feedback AGC (Automatic Gauge Control). Therefore, detailed description is omitted. Moreover, the measured value using a plate thickness meter may be used for the outlet side plate thickness, or a gauge meter plate thickness calculated using a known gauge meter equation may be used.

Further, when the thickness change point of the steel plate 8 reaches the seventh stand 7, the timing instruction device 40 notifies the second plate thickness control devices 26 and 27 of the timing. When the second plate thickness control device 26 of the sixth stand 6 receives a notification from the timing indicating device 40 that the plate thickness change point of the steel plate 8 has reached the seventh stand 7, the plate thickness of the steel plate 8 in the fifth stand 5. The difference between the (exit side plate thickness) and the target thickness value before the start of the change in the fifth stand 5 is obtained as the entrance side plate thickness deviation of the sixth stand 6, and the influence of this entrance side plate thickness deviation is the exit side plate of the sixth stand 6. A second reduction position correction amount ΔS _6b of the sixth stand 6 that prevents the thickness from appearing is obtained and applied to the reduction position control device 6c. Similarly, when the second plate thickness control device 27 of the seventh stand 7 receives a notification from the timing instruction device 40 that the plate thickness change point of the steel plate 8 has reached the seventh stand 7, the steel plate 8 in the sixth stand 6. The difference between the plate thickness (exit side plate thickness) and the plate thickness target value before the start of the change in the sixth stand 6 is obtained as the inlet side plate thickness deviation of the seventh stand 7, and the influence of this inlet side plate thickness deviation is the seventh stand 7. The second reduction position correction amount ΔS _7b of the seventh stand 7 so as not to appear in the outlet side plate thickness is obtained and given to the reduction position control device 7c. In the above, a specific method for obtaining the second reduction position correction amounts ΔS _6b and ΔS _7b so that the influence of the entry side plate thickness deviation does not appear in the output side plate thickness is a known feedforward AGC (Automatic Gauge Control). Since it is similar, detailed description is omitted.

The reduction position control device 5 c of the fifth stand 5 corrects the reduction position of the fifth stand 5 in accordance with the first reduction position correction amount ΔS _{5 a} given from the first plate thickness control device 15. The reduction position control device 6c of the sixth stand 6 includes a first reduction position correction amount ΔS _6a given from the first plate thickness control device 16 and a second reduction position correction amount given from the second plate thickness control device 26. The reduction position of the sixth stand 6 is corrected according to the addition value with ΔS _6b . The reduction position control device 7 c of the seventh stand 7 includes a first reduction position correction amount ΔS _{7 a} given from the first plate thickness control device 17 and a second reduction position correction amount given from the second plate thickness control device 27. The reduction position of the seventh stand 7 is corrected according to the addition value with ΔS _7b .

  Here, the plate thickness control by the first plate thickness control devices 15 to 17 and the second plate thickness control devices 26 and 27 may be started before the start of the change of the plate thickness target value of each stand 5 to 7, The plate thickness target value may be continued after the end of the change, but at least during the change of the plate thickness target value and during the change of the friction coefficient due to the change of non-use of the rolling lubricant, the first plate thickness control device 15- 17 and the second plate thickness control devices 26 and 27 are made to perform the reduction position correction operation.

  Further, when changing the use / non-use of the rolling lubricant, the timing indicating device 40 sends the timing to the lubricant supply means 5e to 7e when the plate thickness change point of the steel plate 8 reaches the seventh stand 7. And the lubricant supply means 5e to 7e change the non-use of the rolling lubricant. By doing in this way, the change start timing of the thickness target value of the 5th stand 5-the 7th stand 7 and the change timing of use non-use of rolling lubricant can be united.

  In addition, when only changing the plate thickness target value without changing the use / non-use of the rolling lubricant, only the operation control regarding the lubricant supply means 5e to 7e is not performed, and the same operation control method as described above is used. Applicable. Also, when changing only the non-use of rolling lubricant without changing the plate thickness target value, the plate thickness change point is the change point of non-use of rolling lubricant, and the change amount of the plate thickness target value is If it is set to 0, an operation control method similar to the above can be applied.

  FIG. 2 is a diagram showing a simplified form of the hot-rolled steel sheet manufacturing apparatus 100 of the present invention. In FIG. 2, in addition to the roughing mill disposed on the upstream side of the tandem finish rolling mill 10 having a plurality of stands 1 to 7 and the winding machine disposed on the downstream side of the cooling device 50, FIG. Reduction position control devices 1c to 7c, speed control devices 1d to 7d, lubricant supply means 1e to 7e, first plate thickness control devices 11 to 17, second plate thickness control devices 12 to 17, and plate thickness target values shown in FIG. The description of the change time determination device 28, the speed command device 30, and the timing instruction device 40 is also omitted, and the tandem finish rolling mill 10 is also shown in a simplified manner. In FIG. 2, the material to be rolled 8 moves from the left side to the right side. As shown in FIG. 2, the hot rolled steel sheet manufacturing apparatus 100 of the present invention is arranged adjacent to a tandem finish rolling mill 10 having a plurality of stands 1 to 7 and on the downstream side of the tandem finish rolling mill 10. And a cooling device 50 provided. In the manufacturing apparatus 100, for example, among the stands 1 to 7 constituting the tandem finish rolling mill 10, after performing high-pressure rolling with a rolling reduction of 30% or more in the three downstream stands 5 to 7, the three Within 0.2 seconds after finishing rolling by the stand 7 disposed on the most downstream side among the stands 5 to 7, the cooling device 50 is used to perform 600 ° C./s or more (preferably 1000 ° C. / The material 8 to be rolled is rapidly cooled at a cooling rate of s or more. By doing in this way, it becomes possible to manufacture ultrafine-grained steel. And since the manufacturing apparatus 100 is equipped with the tandem finish rolling mill 10, it is to be rolled at the time of changing the plate thickness or changing the non-use of the rolling lubricant, which is necessary when manufacturing ultrafine-grained steel. The plate thickness of the material 8 can be controlled. Therefore, according to this invention, the manufacturing apparatus 100 of the hot-rolled steel plate which can improve a yield at the time of manufacture of an ultra fine grain steel can be provided.

  The present invention will be described more specifically with reference to simulation results.

  The thickness of the fifth stand 5 to the seventh stand 7 was changed while a rough bar with a thickness of 32 mm and a width of 1000 mm was rolled in tandem without using rolling lubricant in the draft schedule shown in Table 1. At the same time, a simulation was conducted in which the rolling lubricant of the fifth stand 5 to the seventh stand 7 was started and changed to the draft schedule shown in Table 2. In addition, the draft schedule of Table 2 is a draft schedule aiming at manufacture of an ultra fine grain steel.

  In Tables 1 and 2, “first to seventh” means the first stand 1 to the seventh stand 7.

FIG. 3 shows a rolling state when the operation control method of the tandem finish rolling mill according to the present invention is applied (Example 1). In Example 1, the change of the thickness target value of the fifth stand 5 to the seventh stand 7 and the use of the rolling lubricant are started at time 0, and the thickness of the fifth stand 5 is matched with the thickness target value. first rolling position correction amount [Delta] S _5a of 5 stand _5, the first pressing position correction amount [Delta] S _6a sixth stand 6 to match the thickness of the sixth stand 6 in the thickness target _value, and, the seventh stand 7 The first reduction position correction amount ΔS _7a of the seventh stand 7 that matches the plate thickness with the plate thickness target value was obtained. At the same time, the second stand-down position correction amount ΔS _6b of the sixth stand 6 is obtained based on the plate thickness deviation which is the difference between the exit side plate thickness of the fifth stand and the plate thickness target value before the change start. Based on the thickness deviation, which is the difference between the thickness of the stand on the outlet side and the thickness target value before the start of change, the second reduction position correction amount ΔS _7b of the seventh stand 7 was obtained. Then, the reduction position of the fifth stand 5 is corrected by the first reduction position correction amount ΔS _5a , and the reduction position of the sixth stand 6 is corrected by the first reduction position correction amount ΔS _6a and the second reduction position correction amount ΔS _6b. And the reduction position of the seventh stand 7 is corrected by the addition value of the first reduction position correction amount ΔS _7a and the second reduction position correction amount ΔS _7b . In Example 1, the plate thickness target value change time T was set to 3 seconds so as to be equal to the time required to change the friction coefficient due to the start of use of the rolling lubricant.

  Further, in the case where the plate thickness target value change time T, which was 3 seconds in Example 1, was set to 2 seconds, which was shorter than the time required for changing the friction coefficient due to the use of rolling lubricant, The rolling state of Example 2) is shown in FIG.

On the other hand, as Comparative Example 1, the change of the thickness target value and the start of the use of the rolling lubricant are changed from the fifth stand 5 which is the uppermost stand to be changed to the seventh stand 7 which is the final stand. FIG. 5 shows the rolling state when the change points are sequentially tracked. In Comparative Example 1, a thickness change point is created in the fifth stand 5 at time 0, the change of the thickness target value of the fifth stand 5 and the use of the rolling lubricant are started, and the thickness of the fifth stand 5 is The reduction position correction amount ΔS _5a ′ of the fifth stand 5 that matches the plate thickness target value was obtained to correct the reduction position of the fifth stand 5. When the thickness change point reaches the sixth stand 6, the change of the thickness target value of the sixth stand 6 and the use of the rolling lubricant are started, and the thickness of the sixth stand 6 is changed to the thickness target value. The reduction position correction amount ΔS _6a ′ of the sixth stand 6 matched with the above is obtained to correct the reduction position of the sixth stand 6. Further, when the plate thickness change point reaches the seventh stand 7, the change of the plate thickness target value of the seventh stand 7 and the use of the rolling lubricant are started, and the plate thickness of the seventh stand 7 is changed to the plate thickness target value. The reduction position correction amount ΔS _7a ′ of the seventh stand 7 to be matched with the above is obtained, and the reduction position of the seventh stand 7 is corrected.

Further, the change of the plate thickness target value and the start of use of the rolling lubricant are performed simultaneously from the fifth stand 5 to the seventh stand 7 as in the first embodiment, but the second reduction position correction amount is not used. FIG. 6 shows the rolling state when ΔS _6b = ΔS _7b = 0 (Comparative Example 2).

  In FIGS. 3 to 6, the time when the thickness deviation with respect to the target thickness value after the change of the seventh stand 7 which is the final stand is within ± 0.05 mm or less is rolled from the time 0 to that time. Table 3 shows the results of counting the length of the material to be rolled after rolling as the off-gauge length.

  In Comparative Example 1, since the change of the plate thickness target value and the start of the use of the rolling lubricant are sequentially performed while tracking from the fifth stand 5 to the seventh stand 7, as shown in Table 3, the off-gauge time and Both off-gauge lengths became longer.

  On the other hand, in Comparative Example 2, since the change of the thickness target value of the fifth stand 5 to the seventh stand 7 and the start of the use of the rolling lubricant are performed all at once, as shown in Table 3, the off gauge Although both the time and the off gauge length are shorter than those of Comparative Example 1, the amount of shortening is small. As shown in FIG. 6, the plate thickness in the changing process of the fifth stand 5 becomes a disturbance as the inlet side plate thickness fluctuation of the sixth stand 6 in the time after 3 seconds when the change of the plate thickness target value is completed. Furthermore, the plate thickness in the changing process of the fifth stand 5 and the sixth stand 6 becomes a disturbance as the inlet side plate thickness fluctuation of the seventh stand 7, so that the plate thickness is changed excessively than the change of the plate thickness target value. This is because an overshoot portion is generated.

  On the other hand, in the first embodiment of the present invention, the influence that the plate thickness variation in the process of changing the upstream stands 5 and 6 becomes a disturbance as the inlet side plate thickness variation of the downstream stands 6 and 7 is measured using the second reduction position correction amount. As a result of suppressing the overshoot by canceling, as shown in Table 3, both the off gauge time and the off gauge length were significantly shortened from Comparative Example 1 and Comparative Example 2.

  Further, in Example 2 in which the plate thickness target value change time is shorter than the time required for the change in the friction coefficient due to the start of use of the rolling lubricant, the overshoot portion of the plate thickness remains, and the off gauge time and the off gauge length are in Comparative Example 1. Although it is shorter than Comparative Example 2, it does not reach Example 1. Further, the variation in tension is larger than that in the first embodiment. This is a coefficient of friction that acts to further reduce the plate thickness in 2 to 3 seconds after the target value change from the thick plate thickness shown in Table 1 to the thin plate thickness shown in Table 2 is completed. This is because a decrease occurred. In Example 1 in which the plate thickness target value change time is equal to the time required for the change of the friction coefficient by using the rolling lubricant, the plate thickness target value is as shown in Table 2 for 0 to 3 seconds when the friction coefficient decreases. Since it is thicker than the value after the change, the influence of the decrease in the friction coefficient offsets the decrease in the plate thickness, and the plate thickness target value change time is longer than that in Example 2, but the off gauge time and the off gauge length are It became shorter than Example 2.

  As described above, according to the present invention, it is possible to shorten the off-gauge time and the off-gauge length when changing the plate thickness and / or the non-use of the rolling lubricant, and the yield is improved.

  The present invention can be used for producing a hot-rolled steel sheet having ultrafine crystal grains.

DESCRIPTION OF SYMBOLS 1 ... 1st stand 1a ... Work roll 1c ... Roll-down position control apparatus (roll-down position control means)
1e ... Lubricant supply means 2 ... 2nd stand 2a ... Work roll 2c ... Reduction position control device (reduction position control means)
2e ... Lubricant supply means 3 ... Third stand 3a ... Work roll 3c ... Reduction position control device (reduction position control means)
3e ... Lubricant supply means 4 ... 4th stand 4a ... Work roll 4c ... Reduction position control device (reduction position control means)
4e ... Lubricant supply means 5 ... Fifth stand 5a ... Work roll 5c ... Reduction position control device (reduction position control means)
5e ... Lubricant supply means 6 ... Sixth stand 6a ... Work roll 6c ... Reduction position control device (reduction position control means)
6e ... Lubricant supply means 7 ... 7th stand 7a ... Work roll 7c ... Reduction position control device (reduction position control means)
7e ... Lubricant supply means 8 ... Rolled material 10 ... Tandem finish rolling mill 11, 12, 13, 14, 15, 16, 17 ... First thickness control device (first thickness control means)
22, 23, 24, 25, 26, 27 ... second plate thickness control device (second plate thickness control means)
DESCRIPTION OF SYMBOLS 28 ... Plate thickness target value change time determination apparatus 30 ... Speed command apparatus 40 ... Timing instruction apparatus 50 ... Cooling apparatus 100 ... Manufacturing apparatus of hot-rolled steel

Claims (10)

While rolling one material to be rolled by a tandem finish rolling mill having N (N is an integer of 2 or more) stands, from the m-th stand (m is an integer of 1 to N-1). A method for controlling the operation of a tandem finish rolling mill, in which the thickness target value in the Nth stand is changed,
At the same time when the thickness change point of the material to be rolled reaches the Nth stand, the change of the thickness target value of the nth stand (where n is an integer from m to N) is started,
The n-th stand that matches the plate thickness of the material to be rolled on the exit side of the n-th stand with the plate thickness target value at least in the time zone from the start to the end of change of the plate thickness target value of the n-th stand. While calculating the first reduction position correction amount of
In the nth stand of n> m, the plate is the difference between the plate thickness of the material to be rolled on the exit side of the n-1 stand and the plate thickness target value before the start of change on the exit side of the n-1 stand. The thickness deviation is determined so that the influence of the thickness deviation of the n-1th stand does not appear in the thickness of the material to be rolled on the exit side of the nth stand where n> m. Obtain the second reduction position correction amount of the nth stand,
The reduction position of the m-th stand is corrected momentarily by the first reduction position correction amount, and the reduction position of the n-th stand of n> m is corrected by the first reduction position correction amount and the second reduction position correction. An operation control method for a tandem finish rolling mill, wherein only the value added to the quantity is corrected every moment. While rolling one material to be rolled by a tandem finish rolling mill having N (N is an integer of 2 or more) stands, from the m-th stand (m is an integer of 1 to N-1). A method of controlling the operation of a tandem finishing mill, in which the non-use of rolling lubricant in the Nth stand is changed,
Change the non-use of rolling lubricant of the nth stand (n is an integer from m to N) at the same timing,
The plate thickness of the material to be rolled on the exit side of the nth stand at least in the time zone required to change the friction coefficient between the work roll and the material to be rolled due to the non-use of the rolling lubricant of the nth stand. A first reduction position correction amount of the n-th stand to match the plate thickness target value,
In the nth stand of n> m, a thickness deviation which is a difference between the thickness of the material to be rolled on the exit side of the n-1 stand and the target thickness value on the exit side of the n-1 stand. The nth stand of n> m is determined so that the influence of the thickness deviation of the n-1th stand does not appear in the thickness of the material to be rolled on the exit side of the nth stand of n> m. 2nd reduction position correction amount of
The reduction position of the m-th stand is corrected momentarily by the first reduction position correction amount, and the reduction position of the n-th stand of n> m is corrected by the first reduction position correction amount and the second reduction position correction. An operation control method for a tandem finish rolling mill, wherein only the value added to the quantity is corrected every moment. While rolling one material to be rolled by a tandem finish rolling mill having N (N is an integer of 2 or more) stands, from the m-th stand (m is an integer of 1 to N-1). A method for controlling the operation of a tandem finish rolling mill, in which the thickness target value in the Nth stand and the non-use of rolling lubricant are changed,
At the same time when the thickness change point of the material to be rolled reaches the Nth stand, the thickness target value of the nth stand (where n is an integer of m or more and N or less) and the change of non-use of rolling lubricant is started. And
The n-th stand that matches the plate thickness of the material to be rolled on the exit side of the n-th stand with the plate thickness target value at least in the time zone from the start to the end of change of the plate thickness target value of the n-th stand. While calculating the first reduction position correction amount of
In the nth stand of n> m, the plate is the difference between the plate thickness of the material to be rolled on the exit side of the n-1 stand and the plate thickness target value before the start of change on the exit side of the n-1 stand. The thickness deviation is determined so that the influence of the thickness deviation of the n-1th stand does not appear in the thickness of the material to be rolled on the exit side of the nth stand where n> m. Obtain the second reduction position correction amount of the nth stand,
The reduction position of the m-th stand is corrected momentarily by the first reduction position correction amount, and the reduction position of the n-th stand of n> m is corrected by the first reduction position correction amount and the second reduction position correction. An operation control method for a tandem finish rolling mill, wherein only the value added to the quantity is corrected every moment. The time from the start of change of the thickness target value of the nth stand to the end of change is equal to or longer than the time required for the change of the friction coefficient between the work roll and the material to be rolled, which is caused by the change of non-use of rolling lubricant. The operation control method for a tandem finish rolling mill according to claim 3, wherein: A hot-rolled steel sheet comprising a step of finish-rolling a steel sheet using a tandem finish rolling mill controlled by the operation control method of the tandem finish rolling mill according to any one of claims 1 to 4. Production method. While rolling one material to be rolled by a tandem finish rolling mill having N (N is an integer of 2 or more) stands, from the m-th stand (m is an integer of 1 to N-1). A tandem finish rolling mill in which the thickness target value in the Nth stand is changed,
At the same time when the thickness change point of the material to be rolled reaches the Nth stand, the change of the thickness target value of the nth stand (where n is an integer from m to N) is started,
The n-th stand that matches the plate thickness of the material to be rolled on the exit side of the n-th stand with the plate thickness target value at least in the time zone from the start to the end of change of the plate thickness target value of the n-th stand. A first plate thickness control means for determining the first reduction position correction amount of the m-th stand to the N-th stand;
Based on the difference between the thickness of the material to be rolled on the exit side of the (n-1) th stand with n> m and the target thickness value before the start of changing the (n-1) th stand, the nth stand with n> m A second plate thickness control means of the (m + 1) th stand to the Nth stand,
A reduction position control means of the m-th stand for correcting the reduction position from time to time by the first reduction position correction amount obtained by the first plate thickness control means;
Occasionally, the reduction position is set to the sum of the first reduction position correction amount obtained by the first plate thickness control means and the second reduction position correction amount obtained by the second thickness control means. A rolling position control means for the (m + 1) -th stand to the N-th stand to be corrected every moment;
A tandem finish rolling mill characterized by comprising: While rolling one material to be rolled by a tandem finish rolling mill having N (N is an integer of 2 or more) stands, from the m-th stand (m is an integer of 1 to N-1). A tandem finish rolling mill in which the non-use of rolling lubricant in the Nth stand is changed,
Lubricant supply means for changing the non-use of the rolling lubricant of the n-th stand (where n is an integer from m to N);
The plate thickness of the material to be rolled on the exit side of the nth stand at least in the time zone required to change the friction coefficient between the work roll and the material to be rolled due to the non-use of the rolling lubricant of the nth stand. A first plate thickness control means of the m-th stand to the N-th stand for obtaining a first reduction position correction amount of the n-th stand that matches the plate thickness target value;
Based on the difference between the thickness of the material to be rolled on the exit side of the (n-1) th stand with n> m and the target thickness value on the exit side of the (n-1) th stand, the nth stand with n> m. A second plate thickness control means of the (m + 1) th stand to the Nth stand,
A reduction position control means of the m-th stand for correcting the reduction position from time to time by the first reduction position correction amount obtained by the first plate thickness control means;
Occasionally, the reduction position is set to the sum of the first reduction position correction amount obtained by the first plate thickness control means and the second reduction position correction amount obtained by the second thickness control means. A rolling position control means for the (m + 1) -th stand to the N-th stand to be corrected every moment;
A tandem finish rolling mill characterized by comprising: While rolling one material to be rolled by a tandem finish rolling mill having N (N is an integer of 2 or more) stands, from the m-th stand (m is an integer of 1 to N-1). A tandem finish rolling mill in which the target thickness of the Nth stand and the non-use of rolling lubricant are changed,
Lubricant supply means for changing the non-use of the rolling lubricant of the nth stand (where n is an integer from m to N) at the same time that the thickness change point of the material to be rolled reaches the Nth stand;
At the same time when the thickness change point of the material to be rolled reaches the Nth stand, the change of the target thickness value of the nth stand is started, and at least from the start of change of the target thickness value of the nth stand to the end of change. In the time zone, the first rolling reduction position correction amount of the nth stand is calculated so that the thickness of the material to be rolled on the exit side of the nth stand matches the plate thickness target value. A first thickness control means of the stand;
Based on the difference between the plate thickness of the material to be rolled on the exit side of the (n-1) th stand where n> m and the thickness target value before the start of change on the exit side of the (n-1) th stand, A second plate thickness control means for the (m + 1) th to the Nth stands for obtaining a second reduction position correction amount of the nth stand;
A reduction position control means for the m-th stand that corrects the reduction position momentarily by the first reduction position correction amount obtained by the first plate thickness control means;
Occasionally, the reduction position is set to the sum of the first reduction position correction amount obtained by the first plate thickness control means and the second reduction position correction amount obtained by the second thickness control means. A rolling position control means for the (m + 1) -th stand to the N-th stand to be corrected every moment;
A tandem finish rolling mill characterized by comprising: The time from the start of change of the thickness target value of the nth stand to the end of change is equal to or longer than the time required for the change of the friction coefficient between the work roll and the material to be rolled, which is caused by the change of non-use of rolling lubricant. The tandem finish rolling mill according to claim 8, wherein An apparatus for producing a hot-rolled steel sheet, comprising the tandem finish rolling mill according to any one of claims 6 to 9.

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