JP6323563B2 - Rolling method and rolling apparatus - Google Patents

Description

  The technology of the present disclosure relates to a rolling method and a rolling apparatus for rolled material.

  In the continuous hot rolling line, the temperature calculation of the rolled material in the finish mill from the exit side of the rough rolling mill is related to the quality of the rolled material such as the rolling load calculation, rolling torque calculation, roll profile calculation (thermal crown) at the finishing stand. It is an indispensable calculation element for thickness, crown and shape calculation.

  As for the temperature calculation of the rolled material, for example, as shown in Non-Patent Document 1, for example, a method of calculating a heat conduction equation by a difference method is known as a method of calculating a plate thickness direction temperature distribution. Yes. Japanese Patent Laid-Open No. 7-80517 discloses a method of calculating the temperature distribution in a roll of a work roll composed of two layers having different physical property values in hot rolling, that is, a core material and an outer layer material, during the rolling operation. In addition, as a mathematical expression of the temperature distribution in the roll radial direction, the discontinuity of the temperature gradient in the roll radial direction that inevitably arises from the continuity of the heat flow rate due to the difference in thermal conductivity between the core material and the outer layer material. A method of calculating the amount of thermal expansion in a rolling roll using a representable polynomial is disclosed.

  In the rolling material cooling process, it is known that when a large heat removal occurs due to descaling or contact with a roll, a rapid temperature drop occurs in the surface layer portion of the rolling material. In order to accurately express this phenomenon, “Japan Steel Association Joint Study Group, Rolling Theory Section”, “Theory and Practice of Sheet Rolling”, revised edition, Japan Iron and Steel Institute, September 2010, p. 141 ”(hereinafter referred to as non-patent document 1), it is necessary to finely divide the surface layer of the rolled material. Here, in the setup calculation in the continuous hot rolling line, for example, as shown in FIG. 1, a calculation for achieving the target temperature at the finish mill exit is performed to satisfy the rolling load correction and the set temperature. The calculation is repeatedly performed with corrections such as correction of rolling speed and presence / absence of cooling between stands. If a temperature calculation model in which the rolled material surface layer portion is finely divided is used for such a setup calculation, it takes a long time to calculate the temperature of the rolled material. Therefore, in the temperature calculation model disclosed in Non-Patent Document 1, continuous hot rolling is performed. It was difficult to perform calculation processing in a practical time in the line. In addition, in order to perform the calculation process in a practical time while using the concept of the temperature calculation model disclosed in Non-Patent Document 1, it is necessary to reduce the number of divisions of the calculation area. There was a problem of lowering. Such a problem has been difficult to solve by simply combining the technique disclosed in Non-Patent Document 1 and the technique disclosed in Patent Document 1.

  Therefore, the technology of the present disclosure has a calculation speed that can be used online in a continuous hot rolling line, and can calculate the rolling material temperature with high accuracy, and can roll the rolling material based on the calculation result. It is an object to provide a rolling method and a rolling apparatus.

  The present inventor examined the application of a model that is disclosed in Japanese Patent Application Laid-Open No. 7-80517, which performs highly accurate temperature prediction in a practical calculation time, to temperature calculation of a rolled material in hot rolling. . In patent document 1, when calculating the temperature distribution in the roll of the work roll comprised by the core material and the outer layer material, the polynomial which is different with a core material and an outer layer material is used as numerical expression expression of a roll radial direction temperature distribution. . Therefore, the present inventor first calculated the rolling material temperature without dividing the plate thickness direction of the rolling material. However, if the rolling material temperature is calculated without dividing the plate thickness direction of the rolling material, the calculation accuracy of the temperature of the surface portion of the rolling material is low. As a result of earnest research in response to this result, the present inventor uses a polynomial that can express the temperature distribution in the thickness direction of the rolled material, and includes the surface portion and the thickness center portion of the thickness direction of the rolled material. It has been found that the temperature calculation accuracy of the entire rolled material including the rolled material surface layer portion can be improved by dividing the calculation into at least two sections.

  The technique of this indication was completed based on such knowledge. Hereinafter, the technology of the present disclosure will be described. In addition, in order to facilitate understanding of the technology of the present disclosure, reference numerals in the accompanying drawings are appropriately added in parentheses, but the technology of the present disclosure is not limited to the illustrated form.

  A first aspect of the present invention is a rolling method for rolling a rolled material, wherein the temperature distribution in the plate thickness direction of the rolled material is divided into a region, a section including a plate thickness surface portion, and a section including a plate thickness center portion. The order of the term is determined for each of the at least two or more sections, and the order including the plate thickness surface portion is higher than the section including the plate thickness center portion. The temperature distribution in the plate thickness direction for each of the at least two or more sections is expressed by a polynomial that can express the temperature distribution determined to be, and is expressed using the temperature in the plate thickness direction expressed by the polynomial. It is a rolling method including rolling the rolled material based on the distribution.

  Here, the “section including the plate thickness surface portion” means a predetermined range from the surface layer of the rolled material or the surface layer on the back surface toward the plate thickness center, and the “section including the plate thickness center portion” means the plate thickness surface. This is a region existing on the center side of the plate thickness from the section including the portion. The same applies to other embodiments of the present invention described below.

  In the first aspect of the present invention, it is preferable that the order of the section including the plate thickness center portion is fourth order, and the order of the section including the plate thickness surface portion is 6th order or more.

  In the first aspect of the present invention, it is preferable that the proportion of the section including the plate thickness center portion in the entire plate thickness of the rolled material is increased as the plate thickness of the rolled material is increased.

  2nd aspect of this invention is a rolling mill row | line | column which has a work roll and the inter-stand cooling device, Comprising: The roll speed set with respect to the said work roll, and between the stands set with respect to the said inter-stand cooling device A rolling mill row for rolling the rolled material in accordance with cooling conditions, and a control unit for controlling the rolling mill row, wherein a region in the plate thickness direction of the rolled material is divided into a section including a plate thickness surface portion and a plate thickness center portion. The order of the term is determined for each of the at least two or more sections, and the order includes the plate thickness surface portion rather than the section including the plate thickness center portion. The temperature distribution in the plate thickness direction for each of the at least two or more sections is expressed by a polynomial determined so as to be higher, and the roll speed and the cooling condition between the stands are reduced based on the expressed temperature distribution. Also rolling device and a control unit for changing the one setting.

  According to one embodiment of the present invention, the rolling material temperature is calculated with high calculation accuracy that can be used online in a continuous hot rolling line, and the rolled material is rolled based on the calculation result. It is possible to provide a rolling method and a rolling apparatus capable of

It is a figure explaining an example of the setup schedule in hot finishing rolling. It is a figure explaining an example of the result of having calculated the rolling material temperature, without dividing | segmenting the plate | board thickness direction of a rolling material. It is a figure explaining an example of the depth of the thickness direction of the division of the area | region which represents temperature distribution, and the division containing a plate thickness surface part. It is a figure explaining an example of a temperature parameter. It is a figure explaining an example of the temperature calculation result when the ratio of the section including the plate thickness surface portion occupies the entire plate thickness regardless of the plate thickness, and an example of the calculation result of the rolled material with a thin plate thickness and It is a figure which shows an example of an exact solution. It is a figure explaining an example of the temperature calculation result when the ratio of the section including the plate thickness surface portion to the entire plate thickness is constant regardless of the plate thickness, and an example of the calculation result of the rolled material having a thick plate thickness It is a figure which shows an example of an exact solution. It is a figure explaining an example of the temperature calculation result at the time of changing the ratio for which the plate thickness surface part occupies the whole plate thickness according to the plate thickness, and an example of the calculation result of the rolled material with a thin plate thickness and an example of the exact solution FIG. It is a figure explaining an example of the temperature calculation result at the time of changing the ratio which a plate thickness surface part occupies for the whole plate thickness according to plate thickness, Comprising: An example of a calculation result of a rolling material with thick plate thickness, and an example of exact solution FIG. It is a figure explaining an example of arrangement | positioning of the hot finishing rolling mill row | line | column and thermometer which can apply this invention. It is a figure explaining an example of parameter beta adopted in an example. It is a figure which shows an example of the result of an Example. It is a figure which shows an example of the result of an Example. It is a figure which shows an example of the result of an Example. It is a block diagram which shows an example of the hardware constitutions of the electric system of the rolling material temperature calculation apparatus which concerns on embodiment. It is a block diagram which shows an example of the hardware constitutions of the electric system of the control apparatus which concerns on embodiment. It is a flowchart which shows an example of the flow of the rolling material temperature calculation process which concerns on embodiment. It is a flowchart which shows an example of the flow of the rolling control process which concerns on embodiment. It is a conceptual diagram which shows an example of the aspect by which a rolling material temperature calculation program is installed in the rolling material temperature calculation apparatus which concerns on embodiment. It is a conceptual diagram which shows an example of the aspect by which a rolling control program is installed in the control apparatus which concerns on embodiment.

  Hereinafter, embodiments of the technology of the present disclosure will be described. In addition, the form shown below is an illustration of the technique of this indication and the technique of this indication is not limited to the form demonstrated below.

  The technique of the present disclosure relates to a method for calculating the temperature of a rolled material with high accuracy in a practical calculation time in a continuous hot rolling operation line. As a method for calculating the temperature in a practical calculation time, for example, there is a method disclosed in Patent Document 1. The present inventor decided to adopt this method to calculate the rolling material temperature distribution.

  First, in order to express the rolling material temperature distribution in the plate thickness direction, the plate thickness direction temperature distribution was expressed using a high-order polynomial. At this time, in order to express an abrupt temperature distribution in the surface layer portion of the rolled material, the temperature distribution in the plate thickness direction was calculated using one polynomial (sixth order or higher) in the region in the plate thickness direction. The temperature calculation result (comparative example) of the rolled material after contacting the rolling roll is disclosed in the temperature distribution on the roll bite entry side (temperature distribution of the rolling seat before contacting the rolling roll) and Non-Patent Document 1. FIG. 2 shows the result of calculation by the method of finely dividing the surface portion of the rolled material (which may be referred to as “exact solution” hereinafter).

  As shown in FIG. 2, in the comparative example, in order to express the abrupt temperature distribution in the vicinity of the front and back surfaces of the rolled material temperature, the calculated plate thickness direction temperature distribution has a large amplitude. It was found that the predetermined plate thickness region was far from the exact solution. Therefore, in order to express the rapid temperature in the roll bite during descaling (cooling) and rolling with high accuracy, the technology of the present disclosure uses the region including the plate thickness surface portion ( The temperature distribution in the thickness direction of the rolled material is expressed by dividing it into at least two regions, one example) and a region including the central portion of the plate thickness. In the technique of the present disclosure, the region for calculating the temperature distribution in the plate thickness direction is not particularly limited as long as there is a region including the plate thickness surface portion and a region including the plate thickness center portion, but the temperature of the rolled material is calculated with high accuracy. From the standpoint of easy form, it is preferable to divide into three or more regions each including a plate thickness surface portion, a plate thickness center portion, and a plate thickness back surface portion. Here, the plate thickness rear surface portion is a plate thickness lower surface when the plate thickness surface is the plate thickness upper surface, for example.

  A calculation procedure of the technique of the present disclosure for expressing the temperature distribution in the thickness direction of the rolled material by a polynomial will be described. In the following description, the rolling material temperature is assumed to be a model for calculating the rolling material C cross section (cross section perpendicular to the longitudinal direction of the rolling material). Moreover, in the form shown below, it is assumed that the temperature of both sides is symmetrical with respect to the center in the plate width direction of the rolled material (plate width 2L, plate thickness h), and the plate of the rolled material from the center in the plate width direction of the rolled material. The calculation was performed for the region up to one end in the width direction (a half region of the rolled material). In addition, the technique of this indication can be used also for the temperature calculation of the rolling material whose temperature distribution of both sides is asymmetrical in the board width direction center. In this case, the temperature distribution of the rolled material can be calculated by dividing the temperature distribution into three regions: a region including the plate thickness surface portion, a region including the plate thickness back surface portion, and a region including the plate thickness center portion.

  A basic equation (heat conduction equation) for temperature calculation is expressed by equation (1). Further, the boundary conditions (when descaling and air cooling) in consideration of the above contents are expressed by Expression (2) to Expression (5).

Here, ρ is the specific heat of the rolled material, c is the density of the rolled material, λ is the thermal conductivity of the rolled material, and the third term on the right side of Equation (1) is the work heat generation and friction heat generation terms during rolling. Further, α is a heat transfer coefficient, θ _S is a surface temperature at each location of the rolled material, σ is a Stefan-Boltzmann constant, ε is an emissivity, θ _air is an ambient temperature, and α _R is an equivalent heat transfer coefficient.

  Further, x in the formula (1) is a coordinate in the plate width direction, y is a coordinate in the plate width direction, θ is the temperature, L in the formula (3) is the end position of the plate width, h / 2 in the formula (4), ) -H / 2 represents the surface position in the thickness direction. Further, the superscript e means the end in the plate width direction, the superscript T means the surface (upper surface) of the rolled material, and the upper subscript B means the back surface (lower surface) of the rolled material.

  The boundary condition (rolled material front and back surfaces (upper and lower surfaces)) related to frictional heat generation during rolling is expressed by equation (6), and the boundary condition (rolled material front and back surfaces (upper and lower surfaces)) related to heat removal due to roll contact during rolling is expressed by the equation It is represented by (7).

Here, q _S is the calorific value per unit time generated during rolling, α _W is the heat removal equivalent heat transfer coefficient of roll, and θ _W is the roll temperature.
Considering the boundary condition equations (Equation (2) to Equation (7)), the following equation is obtained by converting the heat conduction equation (Equation (1)) into a weak form.

Here, it is considered that the temperature distribution in the plate thickness direction is approximated by the following polynomial (an example of a polynomial according to the technique of the present disclosure). FIG. 3 shows a schematic diagram when the temperature distribution in the plate thickness direction is expressed in a dimensionless manner by the plate thickness. As shown in FIG. 3, for example, rolling or the like descaling, surface suddenly changes in temperature region (region 3 temperature distribution region 2 and the temperature distribution represented by theta ₂ is represented by theta ₃₎ and Suppose that the temperature distribution in the thickness direction is approximated by a polynomial by dividing it into other regions (region ₁ where the temperature distribution is represented by θ ₁ ). In FIG. 3, β is a boundary between the region 1 and the region 2, and −β is a boundary between the region 1 and the region 3. When a value obtained by dividing the coordinate in the plate thickness direction (y direction) by the plate thickness of the rolled material is y ′, each region (region 1 (−β <y ′ <β), region 2 (β ≦ y ′ ≦ 1) and the temperature distribution in the region 3 (−1 ≦ y ′ ≦ −β)) can be expressed as equations (9) to (11), respectively, as a polynomial of y ′.

Here, a ₁₀ , a ₁₁ , a ₁₂ , a ₁₃ , a ₂₀ , a ₂₁ , a ₂₃ , a ₃₀ , a ₃₁ , a ₃₃ (hereinafter, these may be collectively referred to simply as “a”. ) Are constants for determining the approximate expression, 2n ₁ , 2n ₂ , and 2n ₃ are the orders of the approximate expression, and are parameters set in advance. In expressing θ ₁ , θ ₂ , and θ ₃ in the equations (9) to (11), for example, eight temperature parameters (θ ₀ : plate thickness center temperature, θ _m1 : region θ ₁ shown in FIG. 4 are used. Θ _m2 : average temperature of region θ ₂ , θ _m3 : average temperature of region θ ₃ , θ _2β : boundary temperature between region θ ₁ and region θ ₂ , θ _3β : region θ ₁ and region θ ₃ Boundary temperature, θ _2S : surface temperature of region θ ₂ , θ _3S : surface temperature of region θ ₃ (back surface temperature)). When these eight temperature parameters are applied to the equations (9) to (11), they can be expressed by the following equations (equations (12) to (14)). Here, although the eight temperature parameters shown in FIG. 4 are adopted, the temperature of the rolled material is expressed by a polynomial, but the expression form of the “polynomial capable of expressing the temperature distribution” in the technique of the present disclosure is limited to this. Not. The “polynomial capable of expressing the temperature distribution” can be expressed using other parameters such as a temperature gradient of each region.

  The following equations (Equation (15) to Equation (17)) can be obtained by solving Equations (12) to (14) for a and substituting them into Equations (9) to (11), respectively.

Here, [B ₁ ] ⁻¹ and [B ₂ ] ⁻¹ are inverse determinants obtained by solving for the above a. By arranging the equations (15) to (17), the following equations (equations (18) to (21)) are obtained.

At this time, the temperature distribution in the plate thickness direction is ξ ₀ , ξ _2β , ξ _m1 , ξ _3β , ξ _m2 , ξ _2S , ξ _m3 , and ξ _3S shown in the equations (18) to (20). It can be modeled by expressing it with non-dimensional coordinates. Thereby, one area | region (element) of a plate | board thickness direction can be expressed with a matrix type | formula from Formula (8) and Formula (18)-Formula (21).

  Here, [C] is known as an element heat capacity matrix, [K] is an element heat conduction matrix, and {F} is known as an element heat flux vector. The expression (22) is introduced in, for example, literature ("Analysis of thermal stress, creep, and heat conduction in the finite element method" 1991, third edition, p. 115 to p. 134).

Modeling in the plate width direction can be expressed by linear interpolation between adjacent arbitrary contacts in the plate width direction. For the entire analysis object, all the elements can be gathered with the one region as a whole in the plate width direction and assembled as a whole matrix to obtain simultaneous ordinary differential equations. The target temperature can be obtained by solving the simultaneous ordinary differential equations.

Next, the inventor compares the calculation result by the technique of the present disclosure calculated by the above-described calculation method with the calculation result using the difference method shown in Non-Patent Document 1, for example. 15) to orders 2n ₁ , 2n ₂ , and 2n ₃ expressing the polynomials shown in formula (17) were studied. As a result, it was found that the calculation accuracy can be easily improved by setting n ₁ to 2 or more and n ₂ and n ₃ to 3 or more.

  In the above, β is set in FIG. 4 and formulas (12) to (14) on the premise of three divisions, but it is not necessarily in three divisions, and the division area can be divided into 2m + 1 divisions (m is an integer). The range can also be defined as β, β ′, β ″... (0 <β <β ′ <β ″ <. However, if the number of area divisions is increased, the calculation accuracy is somewhat improved, but the calculation time increases. As in the technique of the present disclosure, it has been found that a method in which the divided region is divided into three and β is set according to the plate thickness can calculate the fastest and highly accurate solution.

  By the way, in the hot rolling operation, sheet thickness reduction (rolling) is performed by a plurality of passes with a rolling mill, and the sheet is rolled to a predetermined sheet thickness. The inventor has set the parameter β (see FIG. 4) for determining the region range on the front and back surfaces of the plate thickness by the above-described calculation method so that the calculation error is reduced with a rolled material having a thin plate thickness (β = 0.6). Then, the value was applied to a rolled material with a large thickness in the hot rolling operation. The results are shown in FIGS. 5A and 5B. FIG. 5A is a diagram showing a calculation result and an exact solution of a rolled material with a thin plate thickness, and FIG. 5B is a diagram showing a calculation result and an exact solution of a rolled material with a thick plate thickness.

  As shown in FIG. 5A and FIG. 5B, when the rolled sheet is thin and the rolled sheet is thick, the parameter β is kept constant when there is a rapid temperature drop in the surface layer of the rolled material such as in a roll bite during rolling or descaling. It was found that a significant error occurred in the temperature distribution in the thickness direction when the value was set. Therefore, the present inventor performed calculation by changing β, which is the parameter, for each plate thickness in order to easily improve the calculation accuracy according to the technique of the present disclosure. A comparison between the result and a calculation result using the difference method shown in Non-Patent Document 1 is shown in FIGS. 6A and 6B. FIG. 6A is a diagram showing a calculation result and an exact solution of a rolled material with a thin plate thickness, and FIG. 6B is a diagram showing a calculation result and an exact solution of a rolled material with a thick plate thickness.

  As shown in FIGS. 6A and 6B, the parameter β is changed according to the plate thickness (β set to 0.6 when the plate thickness is 1.6 mm, and changed to 0.85 when the plate thickness is 40 mm. It was found that the thickness direction temperature distribution can be expressed without degrading the calculation accuracy even when there is a sudden temperature drop in the surface layer of the rolled material such as in the roll bite during rolling or descaling.

  In the technology of the present disclosure, the method for determining the specific value of the parameter β is not particularly limited. The parameter β is, for example, calculated in advance from a strict calculation result using the difference method shown in Non-Patent Document 1, and a temperature region that changes rapidly in the vicinity of the plate surface. The relationship between and can be applied.

  Further, it is also found that the parameter β for determining the region range on the front and back sides of the plate thickness obtained by the above method does not affect the temperature error used in the industry if it is approximately β ± 0.1. doing.

  The calculation using the rolling material temperature calculation method for hot rolling according to the technology of the present disclosure described above can be performed by the calculation unit 1 illustrated in FIG. 1 as an example. The example of a hot rolling line provided with the hot rolling material temperature calculation apparatus which has the calculation part 1 is shown in FIG. In FIG. 7, the form of each device is shown in a simplified manner, and the rolling material temperature calculation device 10 for hot rolling according to the technique of the present disclosure executes a rolling material temperature calculation program 24 (see FIG. 12) described later. It operates as the calculation unit 1.

  The hot rolling line 100L shown in FIG. 7 includes a rough rolling mill 20, a finishing rolling mill row 30 in which a plurality of stands 28 each having a work roll 26 are installed, and the exit side of the rough rolling mill 20 (rolling material Rough rolling mill delivery side thermometer 50 installed on the downstream side in the movement direction (the same applies hereinafter), hot rolling mill temperature calculation device 10, and entry side of the finishing mill train 30 (the rolling material movement direction) Finishing mill row entry side thermometer 60 installed on the upstream side), control device 40 for controlling the operation of finishing mill row 30, and finishing rolling mill row installed on the exit side of finishing mill row 30 A side thermometer 70.

  A descaling cooling device 30 </ b> A is provided on the entry side of the finishing mill row 30, and an inter-stand cooling device 30 </ b> B is provided between the stands 28 of the finishing rolling mill row 30. The descaling cooling device 30A performs descaling by spraying water onto the rolled material. The inter-stand cooling device 30B cools the rolled material by spraying water onto the rolled material.

  In the hot rolling line 100 </ b> L, information related to the temperature of the rolled material measured by the rough rolling mill delivery-side thermometer 50 is sent to the rolling material temperature calculation device 10 for hot rolling. In the rolling material temperature calculation device 10, calculation is performed by the hot rolling material calculation method for hot rolling according to the technique of the present disclosure described above, and the rolling material at the temperature is finish-rolled using the rolling material temperature obtained by the calculation. The rolling speed and the cooling condition of the rolled material between the stands of the finishing mill row 30 are calculated.

  As an example, as shown in FIG. 12, the rolling material temperature calculation device 10 includes a CPU (Central Processing Unit) 12, a primary storage unit 14, and a secondary storage unit 16, which include an address bus, a control bus, a system bus, and the like. Are connected to each other via a bus 18 configured to include

  The primary storage unit 32 is a volatile memory, for example, a RAM (Random Access Memory). The secondary storage unit 34 is a non-volatile memory, for example, a flash memory or an HDD (Hard Disk Drive).

  The rolling material temperature calculation apparatus 10 includes an input / output interface (I / O) 22. The I / O 22 electrically connects the CPU 12 and various input / output devices, and controls transmission / reception of various information between the CPU 12 and various input / output devices.

  The I / O 22 is connected with a control device 40 and a roughing mill outlet thermometer 50 as input / output devices. Therefore, the CPU 12 exchanges various types of information with the control device 40 and acquires information about the temperature measured by the roughing mill outlet thermometer 50 from the roughing mill outlet thermometer 50.

  The secondary storage unit 16 stores a rolling material temperature calculation program 24. The CPU 12 reads the rolling material temperature calculation program 24 from the secondary storage unit 16 and develops it in the primary storage unit 14. Then, the CPU 12 operates as a control unit according to the technique of the present disclosure by executing the rolling material temperature calculation program 24 developed in the primary storage unit 14.

  As an example, as shown in FIG. 13, the control device 40 includes a CPU 42, a primary storage unit 44, and a secondary storage unit 46, which are configured to include an address bus, a control bus, a system bus, and the like. Are connected to each other.

  The primary storage unit 44 is a volatile memory, for example, a RAM. The secondary storage unit 46 is a nonvolatile memory, such as a flash memory or an HDD.

  The control device 40 includes an I / O 52. The I / O 52 electrically connects the CPU 42 and various input / output devices, and controls transmission / reception of various information between the CPU 42 and various input / output devices.

  The I / O 52 is connected with a rolling material temperature calculation device 10, a stand 28, a descaling cooling device 30A, and an inter-stand cooling device 30B as input / output devices. Therefore, the control device 40 exchanges various information with the rolling material temperature calculation device 10, and controls the work roll 26 of the stand 28, the descaling cooling device 30A, and the inter-stand cooling device 30B.

  The secondary storage unit 46 stores a rolling control program 54. The CPU 42 reads the rolling control program 54 from the secondary storage unit 46 and develops it in the primary storage unit 44. Then, the CPU 42 operates as a control unit according to the technique of the present disclosure by executing the rolling control program 54 developed in the primary storage unit 44.

  Next, an example of the flow of the rolling material temperature calculation process realized by the CPU 12 of the rolling material temperature calculation apparatus 10 executing the rolling material temperature calculation program 24 will be described with reference to FIG.

  In the rolling material temperature calculation process shown in FIG. 14, first, in step 100, the CPU 12 performs basic setting for solving the heat conduction equation, and then proceeds to step 102.

  In step 100, as a specific requirement, the CPU 12 sets the approximate polynomial in the plate thickness direction to be analyzed, the plate thickness direction division number, β representing the divided region, the plate width direction division number, and the roughing mill exit side Temperature, boundary conditions related to heat removal and heat input other than rolling in formulas (2) to (5) (for example, descaling and air cooling, bar heater, passage time), rolling in formulas (6) and (7) Set boundary conditions for heat generation inside.

  In the next step 102, the CPU 12 calculates the heat capacity matrix [C] of the element, the heat conduction matrix [K] of the element, and the heat flow vector {F} of the element constituting the simultaneous ordinary differential equation of the equation (22). Then, the entire matrix is created as the entire width direction.

  In the next step 104, the CPU 12 solves the simultaneous ordinary differential equation and calculates the temperature parameter.

  Finally, if necessary, the CPU 12 calculates the temperature of the attention point from Expressions (18) to (20), and then ends the rolling material temperature calculation process.

  Next, an example of the flow of rolling control processing realized by the CPU 42 of the control device 40 executing the rolling control program 54 will be described with reference to FIG.

  In the rolling control process shown in FIG. 15, first, in step 150, the CPU 42 acquires the roll peripheral speed and the cooling condition, and in the next step 152, the rolling material temperature calculation process shown in FIG. 14 is executed. The CPU 42 calculates the finish delivery temperature.

In the next step 154, if the finishing delivery side temperature does not match the target temperature, in the next step 156, the CPU 42 changes the roll speed or / and the cooling condition. Then, the CPU 42 repeats this loop until the finishing delivery side temperature matches the target temperature, and the processing is terminated when they match.

  Here, the roll speed refers to the roll speed of the work roll 26 included in the stand 28. Further, the cooling condition refers to a condition for cooling between the stands of the finishing mill row 30 in which the process of step 100 is performed.

  In addition, although description is abbreviate | omitted, as further shown in FIG. 1, also about rolling load and rolling torque, a load is checked, and if a load is a subject, a sheet thickness schedule will be changed, a sheet thickness schedule, Roll peripheral speed and cooling conditions between stands are fixed.

  Thereafter, when rolling is performed at the roll speed and cooling conditions calculated in this manner, the temperature of the rolling material on the exit side of the finishing mill row 30 due to, for example, fluctuations in cooling water temperature or fluctuations in the injection amount of cooling water. Is determined not to reach the predetermined target temperature, for example, by changing the roll speed and the inter-stand cooling conditions, the temperature of the rolling material on the exit side of the finishing rolling mill row 30 becomes the predetermined target temperature. Until it becomes, the calculation in the rolling-material temperature calculation apparatus 10 is repeated. When the temperature of the rolled material on the exit side of the finishing rolling mill row 30 can be controlled to a predetermined target temperature by rolling at the roll speed and cooling condition calculated by the rolled material temperature calculating device 10, the calculation is performed. The result is output to the control device 40.

  In step 158, the CPU 42 controls the roll speed of the finishing mill row 30 in accordance with the roll speed determined in step 154, and controls the inter-stand cooling device 30B in accordance with the cooling conditions determined in step 154, and then performs the main rolling. The control process ends.

  Thus, since the hot rolling line 100L has the rolling material temperature calculation device 10 capable of performing the hot rolling rolling material temperature calculation method according to the technique of the present disclosure, it is rolled online and with high accuracy. The material temperature can be calculated, and the temperature of the rolled material on the exit side of the finish rolling mill row 30 can be easily controlled to the target temperature. As a result, it becomes possible to reduce the error of the rolling load at each finishing stand due to temperature, and according to the technique of the present disclosure, it is possible to manufacture a hot-rolled steel sheet with a stable plate crown and shape. A possible hot rolling line 100L can be provided.

  As mentioned above, although the form which applied the technique of this indication to the hot finish rolling mill row | line was illustrated, it cannot be overemphasized that the technique of this indication can also be applied to thick plate rolling and cold rolling.

  The technology of the present disclosure will be further described with reference to examples.

  FIG. 7 shows the technique of the present disclosure in a form in which the temperature distribution in the sheet thickness direction of the rolled material is expressed using a polynomial that can represent the temperature distribution in the sheet thickness direction in three and expressing the temperature distribution. The present invention was applied to a hot finish continuous rolling mill (finishing mill row 30 having seven finishing stands). In this embodiment, in the continuous hot rolling process (hot rolling line 100L) shown in FIG. 7, the measured value of the roughing mill outlet thermometer 50 is used as input data of the rolling material temperature, and the roughing mill outlet thermometer is measured. The temperature calculation of the rolled material in the region from 50 to the finishing rolling mill row side thermometer 70 was performed. The parameter β used in the calculation of the technology of the present disclosure is a rigorous calculation using the difference method shown in Non-Patent Document 1, and a temperature region that changes abruptly in the vicinity of the plate surface in advance is defined as a rolling pass outlet side plate thickness. Determined by organizing the relationship. FIG. 8 shows the relationship between the parameter β used in this example and the exit side plate thickness of the finish rolling mill row 30. As shown in FIG. 8, in this embodiment, the parameter β increases as the exit side plate thickness of the finish rolling mill row 30 increases, in other words, the roll increases as the exit side plate thickness of the finish rolling mill row 30 increases. The parameter β was determined so that the ratio of the region 2 and the region 3 occupying the entire thickness of the material was small. In the present embodiment, the relationship between the thickness of the rolling pass outlet side plate is arranged, but the relationship between the parameter β and the rolling pass inlet side plate thickness may be arranged.

  The results of this example are shown in FIGS. FIG. 9 is a diagram for explaining a temperature calculation result performed on a rolled material having an exit side plate thickness of 1.6 mm in the finish rolling mill row 30, and FIG. 10 is an example in which the exit side plate thickness of the finish rolling mill row 30 is 5.5 mm. It is a figure explaining the temperature calculation result performed about a certain rolling material, and FIG. 11 is a figure explaining the temperature calculation result performed about the rolling material whose exit side plate | board thickness of a finishing rolling mill row | line is 15.0 mm. 9 to 11, the thermometer measured value on the coarse rolling mill exit side, the thermometer measured value on the finishing mill train entry side, and the thermometer measured value on the finish rolling mill train exit side are indicated by “◯”, respectively.

  As shown in FIGS. 9 to 11, according to the technique of the present disclosure, in all cases, the surface temperature calculated by the technique of the present disclosure is the measured value of the thermometer on the entry side of the finishing mill and the finishing mill line. It almost coincided with the measured value of the thermometer on the delivery side. From this result, it has been found that according to the technique of the present disclosure, it is possible to represent the rolling material temperature with practical accuracy from a thin region to a thick region in hot finish rolling. Further, the time required for calculation by the technique of the present disclosure is, for example, about 1/5 to 1/10 of the calculation time of exact calculation using the difference method disclosed in Non-Patent Document 1. That is, according to the technique of the present disclosure, the temperature calculation of the rolled material can be speeded up, and the calculation speed of the technique of the present disclosure is a calculation speed that can be used online in a continuous hot rolling line.

  As described above, according to the technology of the present disclosure, the temperature of the rolled material can be calculated with high accuracy, so that the temperature of the rolled material can be easily controlled to a predetermined temperature. As a result, since it becomes possible to reduce the error of the rolling load at each finishing stand due to temperature, it is possible to manufacture a hot-rolled steel sheet with a stable plate crown and shape by using the technology of the present disclosure. Is possible.

  As mentioned above, although the example which applied the technique of this indication to the case of calculating the rolling material temperature of the finish rolling outgoing side in hot continuous rolling was explained, the technique of this indication is used for the temperature calculation of the rolling material in hot rolling. When applying, the application location is not limited to finish rolling. The technique of this indication is applicable also to the operation conditions from a heating furnace exit side to rough rolling.

  In the above embodiment, the case where the roll speed and the cooling condition are calculated by executing the rolling material temperature calculation process (see FIG. 14) is illustrated, but the technology of the present disclosure is not limited thereto. Instead, the roll speed or the cooling condition may be calculated.

  Moreover, in the said embodiment, although the case where the roll speed and cooling conditions were controlled was illustrated, the technique of this indication is not limited to this, First, cooling conditions are controlled and cooling conditions are controlled. Alternatively, the roll speed may be controlled when the temperature of the rolled material does not reach a predetermined target temperature on the exit side of the finish rolling mill row 30.

  In the above-described embodiment, the case where the regions 2 and 3 have a higher degree of polynomial than the region 1 has been described. At this time, when the order of the polynomial in the region 1 is 4th, the order of the polynomial in the region 2 and the order of the polynomial in the region 3 are preferably 6th or higher.

  Moreover, in the said embodiment, although the rolling material temperature calculation apparatus 10 and the control apparatus 40 are implement | achieved by the software structure, the technique of this indication is not limited to this. For example, the rolling material temperature calculation device 10 and the control device 40 may be realized by an ASIC (Application Specific Integrated Circuit). Moreover, the rolling material temperature calculation apparatus 10 and the control apparatus 40 may be implement | achieved by FPGA (Field-Programmable Gate Array). Each of the rolling material temperature calculation device 10 and the control device 40 may be realized by a combination of a hardware configuration and a software configuration.

  Moreover, in the said embodiment, although the rolling material temperature calculation apparatus 10 and the control apparatus 40 are made into a different body, you may integrate.

  Further, in each of the above-described embodiments, the case where the rolling material temperature calculation program 24 is read from the secondary storage unit 16 is exemplified, but it is not necessarily stored in the secondary storage unit 16 from the beginning. For example, as shown in FIG. 16, a rolling material temperature calculation program 24 may be first stored in an arbitrary portable storage medium 200A such as an SSD (Solid State Drive) or a USB (Universal Serial Bus) memory. . In this case, the rolling material temperature calculation program 24 stored in the storage medium 200 </ b> A is installed in the rolling material temperature calculation device 10, and the installed rolling material temperature calculation program 24 is executed by the CPU 12.

  Further, in each of the above embodiments, the case where the rolling control program 54 is read from the secondary storage unit 46 is exemplified, but it is not always necessary to store the rolling control program 54 in the secondary storage unit 46 from the beginning. For example, as shown in FIG. 17, a rolling control program 54 may be first stored in an arbitrary portable storage medium 200B. In this case, the rolling control program 54 stored in the storage medium 200B is installed in the control device 40, and the installed rolling control program 54 is executed by the CPU 42.

  The disclosure of Japanese Patent Application No. 2014-177396 filed on September 1, 2014 is incorporated herein by reference in its entirety.

  All documents, patent applications, and technical standards mentioned in this specification are to the same extent as if each individual document, patent application, and technical standard were specifically and individually stated to be incorporated by reference. Incorporated herein by reference.

  Regarding the above embodiment, the following additional notes are disclosed.

(Appendix 1)
A method for calculating the temperature of a rolled material in hot rolling,
Representing the temperature distribution in the thickness direction of the rolled material, using a polynomial that can represent the temperature distribution,
The hot rolling is characterized in that the region expressing the temperature distribution in the sheet thickness direction by the polynomial is divided into at least two or more sections including a section including a sheet thickness surface portion and a section including a sheet thickness center portion. Material temperature calculation method.

(Appendix 2)
The rolling material temperature of hot rolling according to appendix 1, wherein the ratio of the section including the plate thickness surface portion in the entire plate thickness of the rolled material is changed according to the thickness of the rolled material. Method of calculation.

(Appendix 3)
The rolling material temperature calculation method of hot rolling according to appendix 1 or 2, wherein the polynomial expressing the temperature distribution of the section including the plate thickness surface portion includes a term whose power is 6 or more. .

(Appendix 4)
Represent the temperature distribution in the thickness direction of the rolled material using a polynomial that can represent the temperature distribution,
A region for expressing the temperature distribution in the plate thickness direction by the polynomial is divided into at least two or more of a division including a plate thickness surface portion and a division including a plate thickness center portion, and a calculation unit is provided. A rolling material temperature calculation device for hot rolling.

(Appendix 5)
A hot rolling line comprising a finishing rolling mill row, a thermometer installed upstream of the finishing rolling mill row, and a control device for controlling the operation of the finishing rolling mill row,
Furthermore, it comprises a rolling material temperature calculation device for hot rolling as described in appendix 4,
The rolling material temperature calculation device for hot rolling performs calculation based on temperature information input from the thermometer, and sets the roll speed and / or inter-stand cooling condition of the finishing rolling mill row to the control device. A hot rolling line characterized by output.

Claims (4)

A rolling method for rolling a rolled material,
Dividing the region of the rolled material in the plate thickness direction into at least two or more of a zone including a plate thickness surface portion and a zone including a plate thickness center portion;
Wherein is the order of the at least two divided sections each is defined, the order is defined in the segment each as towards the partition is increased including the thickness surface portion than fraction containing the plate thickness center Represents the temperature distribution in the plate thickness direction for each of the sections ,
For each section, calculate the temperature distribution in the thickness direction with the polynomial,
A rolling method comprising rolling the rolled material based on the temperature distribution in the plate thickness direction calculated for each of the sections . The order of the section including the center portion of the plate thickness is 4th order,
The rolling method according to claim 1, wherein the order of the section including the plate thickness surface portion is 6th order or more.   The rolling method according to claim 1, wherein the ratio of the section including the center portion of the thickness to the total thickness of the rolled material is increased as the thickness of the rolled material increases. Rolling machine row having work rolls and inter-stand cooling device, wherein the rolling material is rolled according to the roll speed set for the work rolls and the inter-stand cooling conditions set for the inter-stand cooling device The train,
The control unit for controlling the rolling mill row, the region of the rolled material in the plate thickness direction is divided into at least two or more of a division including a plate thickness surface portion and a division including a plate thickness center portion, and the order of the at least two divided sections each is defined, the order is determined for the segment each as towards the partition is increased including the thickness surface portion than fraction containing the plate thickness center a polynomial, represents the temperature distribution of the plate thickness direction for each said section, said each segment, the temperature distribution of the plate thickness direction was calculated by the polynomial, the temperature distribution of the calculated the thickness direction for each said section A control unit for changing the setting of at least one of the roll speed and the cooling condition between the stands based on
Including rolling equipment.