Rolling method for cold tandem rolling mill

Abstract

To provide a rolling method of cold tandem rolling mill that predicts interface rising temperature in a roll caliber tool for a rolled material during rolling with high accuracy, and can suppress occurrence of heat scratches.SOLUTION: According to a rolling method of a cold tandem rolling mill, with respect to all stands of a cold tandem rolling mill, interface rising temperatures in a roll caliber tool are respectively calculated from mill motor consumption electric power during rolling, and with respect to each stand, the interface rising temperature and a heat scratch control target temperature preset for each stand are compared. When there is any stand such that the interface rising temperature exceeds the heat scratch control target temperature, a rolling reduction of the stand is changed, and a rolling reduction of other stands is changed so as to maintain total rolling reduction of the cold tandem rolling mill, and rolling is performed on the basis of the rolling reduction.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a rolling method for a cold tandem rolling mill. [Background technology]

[0002] In cold tandem rolling mills, heat scratches can occur due to increases in rolling speed or reduction ratio. A heat scratch is a seizure defect caused by metal-to-metal contact between the work roll and the material being rolled, resulting from an increase in the interface temperature between the work roll and the material being rolled within the roll bite, which causes the oil film within the roll bite to break down.

[0003] Regarding the prevention of heat scratches, methods include using rolling lubricants with excellent seizure resistance, controlling the amount of coolant to lower the temperature of the sheet metal and work rolls, and reducing the work roll speed. These are techniques that suppress the occurrence of heat scratches by preventing the rise in the interface temperature between the work roll and the material being rolled within the roll bite, or by preventing oil film rupture even if the interface temperature within the roll bite rises. However, using rolling lubricants with excellent seizure resistance may increase costs. Also, while controlling the amount of coolant to lower the temperature of the sheet metal and work rolls is effective in suppressing heat scratches, it has low responsiveness. Reducing the work roll speed leads to a decrease in productivity.

[0004] As a technology to prevent the occurrence of heat scratches without hindering productivity, for example, Patent Document 1 discloses a rolling method in a cold tandem rolling mill in which the friction coefficient and deformation resistance are determined based on detected values ​​such as the stand exit plate thickness and rolling load, the roll bite exit plate temperature is estimated based on the detected values, friction coefficient and deformation resistance, and the work roll speed is controlled so that the roll bite exit plate temperature does not exceed the heat scratch control target temperature.

[0005] Also, as a technique for suppressing the occurrence of heat scratches in all stands of a cold tandem rolling mill, for example, Patent Document 2 discloses a rolling method in a cold tandem rolling mill that calculates the interface temperature inside the roll bite and reduces the reduction ratio for stands where the interface temperature inside the roll bite is equal to or higher than the heat scratch generation temperature. Instead, the reduction ratio of other stands is increased to optimize the reduction ratio of all stands.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] Here, in Patent Documents 1 and 2 above, the deformation resistance and the friction coefficient are used to calculate the interface temperature inside the roll bite. As conventional knowledge, the interface temperature is calculated from the plastic working heat generation and the frictional heat generation that occur during rolling. In calculating the plastic working heat generation, it is necessary to accurately predict the deformation resistance of the material to be rolled, and in calculating the frictional heat generation, it is necessary to accurately predict the friction coefficient of the contact portion between the material to be rolled and the work roll. However, considering the variations in operation, it is difficult to always calculate the deformation resistance and the friction coefficient with high accuracy. Also, considering the variations in the hardness and the friction coefficient in the longitudinal direction of the material to be rolled, it is difficult to predict in advance the variations in the deformation resistance and the friction coefficient in the longitudinal direction.

[0008] Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a rolling method for a cold tandem rolling mill that can accurately predict the interface temperature rise on the roll bite of the material to be rolled during rolling in cold tandem rolling and suppress the occurrence of heat scratches. [[ID=

[0009] In order to solve the above problems, according to one aspect of the present invention, for all stands of a cold tandem rolling mill, the interface rising temperature in the roll bite is calculated respectively from the power consumption of the mill motor during rolling, and for each stand, the interface rising temperature is compared with the heat scratch control target temperature preset for each stand. When there is a stand where the interface rising temperature exceeds the heat scratch control target temperature, the reduction ratio of the stand is changed, and the reduction ratios of the other stands are changed so as to maintain the total reduction ratio of the cold tandem rolling mill, and rolling is performed based on the reduction ratio. A rolling method for a cold tandem rolling mill is provided.

[0010] Interface rising temperature T R [[ID= 10]] may be calculated using the following formula (A). Here, Q R [[ID= 12]] [W] is the heat loss due to the interface temperature rise in the roll bite, and is represented by the following (B). W M [[ID= 14]] [W] is the power consumption of the mill motor, W R [[ID= 16]] [W] is the work amount per unit time due to rolling, Q M [[ID= 18]] [W] is the heat loss of the drive system device. Also, α is the distribution ratio in which the heat loss due to the interface temperature rise in the roll bite is distributed to the rolled material and the work roll, ρ s [[ID= 20]] is the density [N / m 3 [[ID= 22]]] of the rolled material, c s [[ID= 24]] is the specific heat [J / kg·°C] of the rolled material.

[0011]

Number

[0012] The distribution ratio α in formula (A) is adjusted based on the surface temperature of the rolled material measured on the exit side of the stand, and the adjusted distribution ratio α is used to calculate the interface rising temperature T R from formula (A).

[0013] [[ID= 41]] Mill motor power consumption W MThis may be predicted based on the rolling load, advance rate, stand exit plate thickness, stand inward tension, and stand exit tension, which are set in advance as a rolling schedule.

[0014] Alternatively, the power consumption W of the mill motor. M This is an actual measured value taken at a predetermined control cycle during operation, and represents the mill motor power consumption W. M Each time it is measured, the interface temperature rise T R The interface temperature rise T is calculated. R If any stand exceeds the heat scratch control target temperature, the reduction ratio of that stand may be changed, and the reduction ratios of the other stands may be changed in real time to maintain the total reduction ratio of the cold tandem rolling mill. [Effects of the Invention]

[0015] As described above, according to the present invention, in cold tandem rolling, it is possible to predict with high accuracy the temperature rise at the interface within the roll bite of the rolled material during rolling, and to suppress the occurrence of heat scratches. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram illustrating the configuration of a cold tandem rolling mill according to one embodiment of the present invention. [Figure 2] This is a schematic perspective view showing the configuration of the stand that constitutes the cold tandem rolling mill according to the same embodiment. [Figure 3] This is a flowchart showing the rolling method of a cold tandem rolling mill according to the same embodiment. [Figure 4] This flowchart shows a rolling method for a cold tandem rolling mill when the reduction ratio of each stand is adjusted in real time during rolling. [Modes for carrying out the invention]

[0017] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. In this specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0018] [1. Overview of Cold Tandem Rolling Mills] First, an overview of the cold tandem rolling mill 1 according to one embodiment of the present invention will be described with reference to Figures 1 and 2. Figure 1 is a schematic explanatory diagram showing the configuration of the cold tandem rolling mill 1 according to this embodiment. Figure 2 is a schematic perspective view showing the configuration of the stands that make up the cold tandem rolling mill 1.

[0019] The cold tandem rolling mill 1 is a piece of equipment configured by arranging multiple stands in the rolling direction. For example, the cold tandem rolling mill 1 shown in Figure 1 has five stands F1 to F5. Each of the stands F1 to F5 is equipped with a pair of work rolls 11 and 12 and a pair of backup rolls 13 and 14, as shown in Figure 2. The pair of work rolls 11 and 12 are rotated using a motor 19 as the power source. The power source of the motor 19 is distributed via a motor spindle 18 to the spindle 15 of the upper work roll 11 and the spindle 16 of the lower work roll 12 at the pinion stand 17. The material to be rolled is rolled by passing it between the pair of work rolls 11 and 12 rotated by the motor 19.

[0020] Each stand F1 to F5 is equipped with a thickness gauge 21 to 25 at its exit side for measuring the plate thickness. The thickness gauges 21 to 25 measure the thickness of the steel plate at the exit side of each stand F1 to F5. In addition, tension meters 31 to 36 are provided at the entrance side of stand F1, between adjacent stands (between F1 and F2, F2 and F3, F3 and F4, and F4 and F5), and at the exit side of stand F5 for obtaining the tensile stress acting on the steel plate. Furthermore, a thermometer 40 for measuring the surface temperature of the steel plate may be provided at the exit side of at least one stand. For example, in the cold tandem rolling mill 1 shown in Figure 1, a thermometer 40 is provided at the exit side of stand F4. In addition, each stand F1 to F5 is equipped with a speed meter 51 to 55 for measuring the plate speed.

[0021] Furthermore, each stand F1 to F5 is equipped with a load cell (not shown) for measuring the rolling load, located between the roll chock (not shown) of the backup roll 13 and the reduction cylinder (not shown), or between the roll chock (not shown) of the backup rolls 13 and 14 and the keeper plate (not shown).

[0022] In the cold tandem rolling mill 1, steel plates are sequentially rolled by stands F1 to F5 to produce steel plates of a predetermined thickness.

[0023] [2. Rolling using a cold tandem rolling mill] [2-1. Method for calculating the temperature rise at the interface within a roll bite] In technologies for preventing heat scratches, such as those described in Patent Documents 1 and 2 above, it is necessary to predict the interface temperature rise within the roll bite with high accuracy. However, due to variations in operation, it is difficult to accurately calculate the deformation resistance and friction coefficient used to predict the interface temperature rise within the roll bite. As a result of investigating these issues, the inventors of this application have found that the deformation resistance and friction coefficient can be calculated with high accuracy based on the power consumption of the motor 19 that drives the work rolls 11 and 12 during rolling (mill motor power consumption). If the deformation resistance and friction coefficient can be calculated with high accuracy, the accuracy of predicting the interface temperature rise within the roll bite can be improved, and the occurrence of heat scratches can be suppressed by adjusting the reduction ratio of each stand F1 to F5 so that the predicted interface temperature rise within the roll bite does not exceed the heat scratch occurrence temperature.

[0024] First, the power consumption of the motor 19 that drives the work rolls 11 and 12 during rolling (mill motor power consumption W) M The relationship between this and the heat loss due to the rise in interface temperature within the roll bite per unit time is shown by equation (1) below.

[0025] Mill motor power consumption (W) M )[W] = Work done per unit time by rolling (W) R )[W] + Heat loss due to temperature rise at the interface within the roll bite (Q R )[W] + Heat loss of drive system (Q M )[W] ...(1)

[0026] In the above equation (1), the power consumption W of the mill motor during rolling. M [W] can be measured in real time by measuring the motor current [A] and motor voltage [V]. Also, the amount of work done per unit time by rolling (W) R This includes the rolling load P [N], the rear tension S1 (tension on the stand exit side) [N], the front tension (tension on the stand in side) S0 [N], and the pre-calculated torque arm coefficient λ. GIt can be calculated from [-]. First, calculate the rolling torque G [N·m] using the following formula (2).

[0027]

number

[0028] Here, l is the projected contact arc length [m], R is the work roll radius [m], and R' is the work roll radius considering flattening deformation [m]. Using this calculated rolling torque, the amount of work done per unit time by rolling W is calculated using the following equation (3). R This is calculated.

[0029]

number

[0030] Here, f s σ is the advance rate [-], h0 is the stand side plate thickness [m], and σ0 is [N / m]. 2 ] is the forward tensile stress, σ1[N / m 2 ] is the rear tensile stress. Advancement rate f s This can be calculated, for example, from the work roll speed and the plate speed measured by plate speedometers 51-55 shown in Figure 1. The plate thickness h0 on the stand exit side can be measured, for example, by plate thickness gauges 21-25 shown in Figure 1. The forward tension stress σ0 is the force acting per unit area calculated from the tension on the stand entry side, and the rear tension stress σ1 is the force acting per unit area calculated from the tension on the stand exit side. The tension on the stand entry side and the tension on the stand exit side can be measured, for example, by tension meters 31-36 shown in Figure 1. Note that equation (3) shows the amount of work required to roll the rolled material per unit volume.

[0031] In addition, the heat loss of the drive system, including the motor 19 and gears, can be calculated by measuring the mechanical loss of the drive system in advance. The general method for measuring the mechanical loss is to drive the motor 19 while it is not rolling, and use the motor current or torque measured for each speed as the mechanical loss. For example, the motor current measured using this method can be used as the mechanical loss G. M In this case, the heat loss Q of the drive system is as shown in equation (4) below. M [W] is Mechalos G M Motor voltage V M It is calculated by multiplying by .

[0032]

number

[0033] By measuring or calculating these items, the heat loss Q due to the rise in interface temperature within the roll bite can be calculated using the following equation (5), which is a modified version of equation (1) above. R [W] can be calculated.

[0034]

number

[0035] The heat loss Q due to the rise in interface temperature within the roll bite is calculated using the above formula (5). R Converting [W] to temperature gives the temperature rise at the interface of the rolled material. Heat loss Q due to temperature rise at the interface within the roll bite. R It is distributed between the rolled material and the work rolls 11 and 12. If the distribution ratio is α[-], then the interface temperature rise T of the rolled material. R [℃] is expressed by the following formula (6). Note that ρ s The density of the rolled material [N / m³] 3 ], c s is the specific heat [J / kg·℃] of the rolled material. The distribution ratio α is set to approximately 0.3 to 0.7, and is generally set to approximately 0.5.

[0036]

number

[0037] The calculation of the interface temperature rise within such a roll bite can generally be performed without calculating the deformation resistance and friction coefficient, which vary considerably. Therefore, the interface temperature rise within the roll bite can be calculated with high accuracy.

[0038] [2-2. Rolling method for cold tandem rolling mill] By using the above-described method for calculating the interface temperature rise within the roll bite, the accuracy of predicting the interface temperature rise within the roll bite is improved. By adjusting the reduction ratio of each stand F1 to F5 so that the predicted interface temperature rise within the roll bite does not exceed the heat scratch occurrence temperature, the occurrence of heat scratches can be suppressed.

[0039] Specifically, the rolling method of the cold tandem rolling mill according to this embodiment is as shown in Figure 3, first, for all stands, the power consumption W of the mill motor during rolling. M From the interface temperature rise T within the roll bite R The following is calculated for each (S100). Next, for each stand, the interface temperature rise T R The temperature is compared with the target temperature for heat scratch control (S110). The target temperature for heat scratch control is the upper limit of the interface temperature rise that does not cause heat scratches, or a temperature below that, and is predetermined by experiments with the actual machine. Interface temperature rise T in the roll bite R If the temperature is below the target temperature for heat scratch control, heat scratches will not occur.

[0040] In step S110, the interface temperature rise T RIf any stand exceeds the heat scratch control target temperature, the reduction ratio of that stand is changed, and the reduction ratios of the other stands are changed to maintain the total reduction ratio of the cold tandem rolling mill (S120). Here, the total reduction ratio is the reduction ratio obtained from the entry side plate thickness of the first stand and the exit side plate thickness of the final stand in the cold tandem rolling mill. By reducing the reduction ratio of stands where the interface temperature rise inside the roll bite exceeds the heat scratch control target temperature, processing heat generation and frictional heat generation are reduced, and the interface temperature rise inside the roll bite can be lowered. On the other hand, if the reduction ratio of stands where the interface temperature rise inside the roll bite exceeds the heat scratch control target temperature is reduced, the desired product plate thickness cannot be obtained. Therefore, the reduction ratio of stands where the interface temperature rise inside the roll bite has sufficient margin to reach the heat scratch control target temperature is increased, and the total reduction ratio of the cold tandem rolling mill is kept unchanged. This makes it possible to obtain the desired product plate thickness without generating heat scratches.

[0041] Temperature T of the interface rise within the roll bite R If there are no stands that exceed the heat scratch control target temperature, the reduction ratio is not changed (S130). Then, rolling is performed by a cold tandem rolling mill based on the finally set reduction ratio, i.e., the reduction ratio changed in step S120, or the reduction ratio that was left unchanged in step S130 (S140).

[0042] The rolling method of the cold tandem rolling mill is carried out using a control device (not shown) that controls the cold tandem rolling mill. The control device may consist of an information processing device such as a computer equipped with a CPU, ROM, RAM, etc.

[0043] This cold tandem rolling method allows for highly accurate prediction of the temperature rise at the interface within the roll bite of the material being rolled during rolling, thereby keeping the steel plate temperature below the temperature at which heat scratches do not occur. The cold tandem rolling method according to this embodiment may be performed before rolling to adjust the reduction ratio of a preset rolling schedule in order to prevent heat scratches, or it may be performed in real time during rolling to adjust the reduction ratio of each stand.

[0044] [2-2-1. Adjustment of reduction ratio before rolling] For example, when adjusting the reduction ratio of a pre-set rolling schedule, the processes in steps S100 to S130 in Figure 3 are performed before rolling. In this case, in step S100, the amount of work done per unit time by rolling W is calculated from the rolling load, advance rate, stand exit plate thickness, stand entry tension, and stand exit tension of each stand set in the rolling schedule. R In addition to calculating, Measured values ​​of motor current [A] and motor voltage [V] From mill motor power consumption W M of Calculate the heat loss Q of the drive system. M These values ​​have been measured in advance. Using these values, the interface temperature rise T can be obtained from equations (5) and (6) above. R The reduction ratio is calculated. Then, the reduction ratio changed in step S120, or the reduction ratio that was left unchanged in step S130, is set as the final reduction ratio to be set as the rolling schedule, and rolling is carried out in step S140 using a cold tandem rolling mill.

[0045] [2-2-2. Real-time adjustment of the reduction ratio] Furthermore, if the reduction ratio of each stand is adjusted in real time during rolling, the reduction ratio of each stand is changed sequentially while rolling one steel plate. The rolling method in this case is shown in Figure 4. As shown in Figure 4, when rolling of the steel plate starts (S200), the reduction ratio is adjusted at a predetermined control cycle (S210~S250). The predetermined control cycle can be set arbitrarily, for example, to 1 second. In this case, the reduction ratio is adjusted every second during the rolling of the steel plate.

[0046] First, for all stands, the rolling load, advance rate, stand exit plate thickness, stand entry tension, and stand exit tension are measured, and the motor current and voltage are also measured (S210). The rolling load is measured by load cells installed on each stand. The stand exit plate thickness, stand entry tension, and stand exit tension are measured by a plate thickness gauge and tension meter installed on the cold tandem rolling mill, respectively. The advance rate is calculated from the plate speed measured by a plate speed meter.

[0047] Next, for all stands, the power consumption W of the mill motor during rolling. M From the interface temperature rise T within the roll bite R The following values ​​are calculated (S220). Power consumption W of the mill motor during rolling. M [W] can be calculated in real time by measuring the motor current [A] and motor voltage [V]. Also, the amount of work done per unit time by rolling (W) is calculated. R The rolling load P[N] and the advance rate f were measured in step S210. s [-], stand exit plate thickness h0 [m], rear tension S1 (stand exit tension) [N], front tension (stand in-side tension) S0 [N], and pre-calculated torque arm coefficient λ G It can be calculated from [-]. Heat loss Q of the drive system M These values ​​have been measured in advance. Using these values, the interface temperature rise T can be obtained from equations (5) and (6) above. R This is calculated.

[0048] And for each stand, the interface temperature rise T RThe temperature is compared with the target temperature for heat scratch control (S230). Interface temperature rise T R If any stand exceeds the heat scratch control target temperature, the reduction ratio of that stand is changed, and the reduction ratios of the other stands are changed to maintain the total reduction ratio of the cold tandem rolling mill (S240). Meanwhile, the interface temperature rise T R If there are no stands that exceed the heat scratch control target temperature, the reduction ratio is not changed (S250). The processes in steps S230 to S250 can be carried out in the same way as the processes in steps S110 to S130 in Figure 3.

[0049] Once the processes in steps S210 to S250 are completed, the processes in steps S210 to S250 are executed again in the next control cycle. The processes in steps S210 to S250 are repeated until the rolling of the steel sheet is complete, at which point the process is terminated.

[0050] [2-2-3. Calibration of the interface temperature rise within the roll bite] In the rolling method of the cold tandem rolling mill according to this embodiment, if the accuracy of the interface temperature rise within the roll bite, which is compared with the heat scratch control target temperature, is improved, the presence or absence of heat scratches can be determined with greater accuracy. Therefore, the distribution ratio α in the above formula (6) for calculating the interface temperature rise within the roll bite may be adjusted based on the surface temperature of the steel plate measured at the stand exit to improve the accuracy of the interface temperature rise within the roll bite.

[0051] For example, consider the F4 stand in Figure 1. A thermometer 40 is installed at the exit side of the F4 stand, at a predetermined distance downstream in the rolling direction from the roll bite of the F4 stand. The surface temperature of the steel plate measured by the thermometer 40 ("measured temperature T") m1 The measured temperature T is the surface temperature of the steel sheet at a predetermined distance downstream in the rolling direction from the roll bite of the F4 stand. m1 From the surface temperature of the steel plate at the roll bite position of the F4 stand ("Calculated interface temperature T") m2 This allows us to find the value of ).

[0052] Then, the interface temperature rise T within the roll bite is calculated using the above equation (6). R and the calculated interface temperature T m2 The difference ΔT is calculated, and the distribution ratio α is adjusted so that the difference ΔT = 0. By using the distribution ratio α thus calculated, the accuracy of equation (6) can be improved by determining the interface temperature rise within the roll bite from equation (6) above.

[0053] The distribution ratio α should only be adjusted when rolling conditions are changed, such as when rearranging the rolls. Also, the measurement temperature T m1 The thermometer 40 used to obtain the temperature should be placed on the side of the stand where heat scratches are likely to occur. [Examples]

[0054] To confirm the effect of reducing heat scratch generation according to the present invention, rolling was performed under the following equipment configuration and rolling conditions.

[0055] [Equipment configuration] Number of stands: 2-7 stands Work roll diameter: 200~800mm Backup roll diameter: 1000~1800mm [Rolling conditions] Steel type: C mass%: 0.001~3.0% Inlet side plate thickness: 0.1~10mm Reduction ratio: 1.0~50% (per stand) Work roll peripheral speed: 10-3000 m / min (Lubricant) Types of lubricants: Synthetic esters, mineral oils, vegetable oils (e.g., palm oil), animal oils (e.g., beef tallow) Supply form: Emulsion (concentration 0.1%~20%), neat

[0056] As an example, the rolling method of the cold tandem rolling mill described in Figure 3 was applied to a cold tandem rolling mill in a steel plant, and 1000 rolls were produced under the above equipment configuration and rolling conditions. The distribution ratio α in equation (6) above was set to 0.48.

[0057] On the other hand, as a comparative example, using the above equipment configuration and rolling conditions, the target temperature for heat scratch control was calculated from the heat generated during plastic deformation and the coefficient of friction using the method described in Patent Document 2, which is a prior art, and the reduction ratio of each stand was determined, and 1000 rolls were rolled.

[0058] The experimental results showed that heat scratches occurred in 38% of the steel plates in the comparative example, while the incidence of heat scratches in the example was 0%. Furthermore, the results of four out of 1000 samples in both the example and comparative example are shown in Table 1 below as Examples 1-4 and Comparative Examples 1-4. Table 1 shows the results from the F2 stand. The overall evaluation criteria in Table 1 were as follows.

[0059] [Overall Rating] A: No heat scratches, high pressure reduction rate B: No heat scratch occurrence, low pressure reduction. C: Heat scratch occurred

[0060] [Table 1]

[0061] In Examples 1-4, no heat scratches occurred. On the other hand, in Comparative Example 1, heat scratches occurred because the estimated reduction ratio was too high. In Comparative Example 2, no heat scratches occurred, but the actual reduction ratio was lower than in Example 2, and even greater reduction was possible. In Comparative Example 3, heat scratches occurred because the estimated reduction ratio was too high. In Comparative Example 4, no heat scratches occurred, but the actual reduction ratio was lower than in Example 4, and even greater reduction was possible.

[0062] In the comparative example, heat scratching occurred when the work roll peripheral speed was 1600 mpm. On the other hand, in the embodiment, when the interface temperature rise within the roll bite of the F2 stand exceeded the target temperature for heat scratch control, the reduction ratio of the F2 stand was lowered, and instead, the reduction ratio of the F1 stand, or in the case of a cold tandem rolling mill with four or more stands, the reduction ratio of the F1 stand and the F3 stand was increased. As a result, in the embodiment, heat scratching did not occur even when the work roll peripheral speed was 1600 mpm.

[0063] Although preferred embodiments of the present invention have been described in detail above with reference to the attached drawings, the present invention is not limited to these examples. It is clear to any person with ordinary skill in the art to which the present invention belongs that various modifications or alterations can be conceived within the scope of the technical idea described in the claims, and these are also understood to fall within the technical scope of the present invention. [Explanation of Symbols]

[0064] 1. Cold tandem rolling mill 11, 12 Work Roles 13, 14 Backup Role 15, 16 spindles 17 Pinion Stand 18 Motor spindles 19 Motor 21~25 Thickness gauge 31-36 Tension Meter 40 thermometer 51~55 Plate speedometer

Claims

1. For all stands of the cold tandem rolling mill, the interface temperature rise TR within the roll bite was calculated from the mill motor power consumption WM during rolling using the following formula (A). For each stand, the interface temperature rise T is compared with the heat scratch control target temperature set in advance for each stand. If there is a stand where the interface rise temperature T R exceeds the heat scratch control target temperature, the reduction ratio of that stand is changed, and the reduction ratios of the other stands are changed to maintain the total reduction ratio of the cold tandem rolling mill. A rolling method for a cold tandem rolling mill, wherein rolling is performed based on the aforementioned reduction ratio. Q R [W] is the heat loss due to the rise in interface temperature within the roll bite, and is expressed as shown in (B) below. W M [W] is the power consumed by the mill motor, W R [W] is the amount of work done per unit time by rolling, and Q M [W] is the heat loss of the drive system. Furthermore, α is the distribution ratio in which heat loss due to the rise in interface temperature within the roll bite is distributed between the rolled material and the work roll, ρ s is the density of the rolled material [N / m³], and c s is the specific heat of the rolled material [J / kg·℃]. [Math 1]

2. The distribution ratio α in formula (A) above is adjusted based on the surface temperature of the rolled material measured at the exit of the stand. Using the adjusted distribution ratio α, the interface temperature rise T is obtained from equation (A). Ｒ A rolling method for a cold tandem rolling mill according to claim 1, which calculates the following.

3. The rolling method for a cold tandem rolling mill according to claim 1 or 2, wherein the amount of work W R per unit time by rolling is predicted based on the rolling load, advance rate, stand exit plate thickness, stand in tension, and stand exit tension set in advance as a rolling schedule.

4. The aforementioned mill motor's power consumption W Ｍ This is an actual measured value taken at a predetermined control cycle during operation. The aforementioned mill motor's power consumption W Ｍ Each time the interface temperature rise T is measured, Ｒ Calculate, The interface temperature rise T Ｒ The rolling method for a cold tandem rolling mill according to claim 1 or 2, wherein if there is a stand whose temperature exceeds the heat scratch control target temperature, the reduction ratio of that stand is changed, and the reduction ratios of the other stands are changed in real time to maintain the total reduction ratio of the cold tandem rolling mill.

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