JP2017164796A - Shape control method in cold rolling - Google Patents

Abstract

PURPOSE: To prevent both of drawing and plate breaking in the whole rolling direction area from the rolling start through the rolling end, between stands in a cold tandem mill.CONSTITUTION: A shape control method in cold rolling comprises: determining a drawing limit value of tension at an outlet side of a plate end part that causes drawing in a rolling material, a breaking limit value of tension at the outlet side of the plate end part that causes plate breaking in the rolling material, and a relationship between rolling speeds and friction coefficients, in advance; creating a prediction formula representing the tension of the outlet side of the plate end part; calculating a control quantity for shape control means that makes the tension at the outlet side of the plate end part at the rolling material rolling starting time calculated by the prediction formula, to be equal to or greater than the drawing limit value as well as to be equal to or less than the breaking value; setting the calculated control quantity as a control quantity for the shape control means; predicting rolling loads continuously according to changes of the rolling speed on the basis of the relationship between the rolling speeds and the friction coefficients; recalculating the control quantity for the shape control means to make the tension at the outlet side of the plate end part calculated by the prediction formula to be equal to or greater than the drawing limit value as well as to be equal to or less than the breaking value; and performing correction using the recalculated control quantity as the control quantity for the shape control means.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a method for optimizing rolling conditions so that a rolled metal strip does not cause sheet breakage and narrowing.

  When rolling a steel strip in a cold rolling mill, a rolling shape defect is caused depending on the thickness of the steel strip and rolling conditions, resulting in poor product quality. Specifically, the rolling shape defect is a medium-elongation shape (the central portion of the length distortion in the rolling direction is extended) or an ear extension shape (of the length distortion in the rolling direction, the rolled material). For example, both ends of the end of the substrate may extend).

  In order to suppress such shape defects, in cold tandem mills, the plate shape between stands can be set by setting the control amount of the shape control means such as work roll bender, intermediate roll bender, intermediate roll shift to an appropriate value. It is designed not to get worse. However, there are many small cracks at the end of the plate, so if the average exit tension is large or the rolled material between the stands has a medium elongation, the exit tension on the end of the plate becomes excessive. Breakage may occur.

  Therefore, in Japanese Patent Application Laid-Open No. 4-200904, the plate breaks by controlling the shape so that the steepness of the end of the metal band between the stands of the cold tandem mill is not less than the limit value where the ear crack does not grow. A cold rolling method for preventing the above has been proposed. This is a method of preventing plate breakage by reducing the plate end portion exit side tension when the average exit side tension is small and the rolled shape between the stands becomes an extended ear shape.

  However, in the method disclosed in Japanese Patent Laid-Open No. 4-200904, the plate end portion exit side tension becomes excessive when the average exit side tension is large and the degree of ear extension is light, and the plate may break.

  Therefore, in Japanese Patent Laid-Open No. 8-141620, the total tension is reduced when the plate end portion exit side tension calculated based on the output of the shape detector in the cold reverse rolling mill becomes larger than a predetermined value. Therefore, a shape control method in a rolling mill has been proposed in which shape control is performed with the sheet end portion exit side tension being equal to or less than a predetermined value.

Japanese Patent Laid-Open No. 4-200904 JP-A-8-141620

  In the method of Patent Document 2, the shape of the material to be rolled is detected by a shape detector, and at least one of the maximum value of the unit tension in the width direction and the position unit tension in the specific width direction is more than a predetermined value. By reducing the total tension when it becomes larger, the plate end portion exit side tension can be reduced, thereby preventing the plate from breaking.

  However, in the method of Patent Document 2, the plate end portion exit side tension may be too small, and the rolled material may be narrowed down. The rolling load varies depending on the rolling speed. Generally, the load decreases as the rolling speed increases, and increases as the rolling speed decreases. In the rolling process, when the material starts to be put (at the start of rolling), it gradually changes from the low speed state (low speed part) to the high speed state (high speed part), and when the material is pulled out (at the end of rolling), the low speed state (low speed part) is restored Become. If it does so, a load will change with the front-end | tip of a board, and the middle, and a difference will also arise in board thickness.

  Specifically, the rolling oil uptake amount and the friction coefficient increase at the low speed part of the rolling speed at the start and end of rolling compared to the high speed part, thereby increasing the rolling load, and the rolling material. The rolling shape changes to the ear extension side. Here, the low speed portion at the start and end of rolling includes a low speed portion at the start and end of rolling of one coil in the case of continuous rolling by welding coils as shown in FIG. Therefore, in order to prevent the plate breakage at the high speed part, if the plate end part exit side tension is reduced, the plate end part exit side tension becomes too low due to the shape of the ear extension at the low speed part, and the rolled material is narrowed down. There is. Also, even in the region where the rolling speed changes from the low speed part to the high speed part or from the high speed part to the low speed part, depending on the control of the plate end portion exit side tension, the plate end portion exit side tension may become too small and narrowing may occur. is there.

  The present invention has been devised to solve such a problem, and an object thereof is to provide a shape control method for preventing both narrowing and sheet breakage throughout the rolling direction from the start to the end of rolling. To do.

  In order to achieve these objects, the invention described in claim 1 includes a narrowing limit value of a plate end portion exit side tension at which a rolled material is squeezed, a rupture limit of a plate end portion exit side tension at which the rolled material is ruptured. Value and the correlation between the rolling speed and the friction coefficient are obtained in advance, and a prediction formula representing the strip end portion exit side tension is created in advance, and the plate end portion output calculated by the prediction formula at the start of rolling of the rolled material is calculated. After calculating the control amount of the shape control means so that the side tension is not less than the narrowing limit value and not more than the fracture limit value, and setting the calculated control amount as the control amount of the shape control means, the rolling speed and the friction Based on the correlation with the coefficient, the rolling load is continuously predicted according to the change in the rolling speed, and the plate end portion exit side tension calculated by the prediction formula is not less than the narrowing limit value and not more than the fracture limit value. The control amount of the shape control Out, by correcting the control amount calculated 該再 degree as a controlled variable of the shape control means is a shape control method in a cold rolling and controlling the plate end exit side tension.

  The invention according to claim 2 is the limit value of the tension at the strip end side where the rolling material is squeezed, the limit value of the strip end side tension at which the rupture occurs in the rolled material, and the rolling speed and friction coefficient. Is calculated in advance, and a prediction formula representing the sheet end portion exit side tension is created in advance using the average exit side tension, rolling load, and control amount of the shape control means as variables, and the average is calculated at the start of rolling of the rolled material. Substituting the predicted value of the exit side tension and the rolling load into the prediction formula representing the end side exit side tension of the plate end, so that the end side exit side tension is not less than the narrowing limit value and not more than the fracture limit value. After calculating the control amount of the shape control means and setting the calculated control amount as the control amount of the shape control means, it is continuously changed according to the change of the rolling speed based on the correlation between the rolling speed and the friction coefficient. Predict the rolling load, the average exit tension and the prediction The rolling load is substituted into the prediction formula, and the control amount of the shape control means is calculated so that the plate end portion exit side tension is not less than the narrowing limit value and not more than the fracture limit value, and the calculated control is calculated. The shape control method in cold rolling is characterized in that the sheet end portion exit side tension is controlled by correcting the amount to the control amount of the shape control means.

  The invention according to claim 3 is the limit value of the tension at the strip end side where the rolling material is squeezed, the limit value of the strip end side tension at which the plate material is ruptured, the rolling speed and the friction coefficient. Is calculated in advance, and a prediction formula representing the exit end tension of the plate edge is created in advance using the average exit tension, rolling load, material crown amount and control amount of the shape control means as variables, and rolling of the rolled material is started. At that time, the average delivery side tension, the predicted value of the rolling load, and the material crown amount are substituted into the prediction formula, and the plate end exit side tension is not less than the narrowing limit value and not more than the fracture limit value. And calculating the control amount of the shape control means, and setting the calculated control amount as the control amount of the shape control means, and then responding to the change in the rolling speed based on the correlation between the rolling speed and the friction coefficient. Predict the rolling load continuously. Substituting the average exit side tension, the predicted rolling load and the material crown amount into the prediction formula, and the shape control means so that the exit end tension of the plate end portion is not less than the narrowing limit value and not more than the fracture limit value. A shape control method in cold rolling, wherein the sheet end portion exit side tension is controlled by correcting the calculated control amount to the control amount of the shape control means. is there.

  The invention according to claim 4 further measures the rolling load continuously in a constant speed region of a low speed part of the rolling speed at the start and end of rolling of the rolled material and a high speed part of the rolling speed during rolling. The sheet end portion exit side tension is controlled by using the measured rolling load instead of the predicted value of the rolling load calculated by the prediction formula. This is a shape control method in cold rolling.

  As described above, in the present invention, it is possible to prevent both narrowing and sheet breakage across the entire rolling direction from the start to the end of rolling between the stands of the cold tandem mill.

It is a figure explaining the low speed part of the rolling speed at the time of the rolling start and completion | finish, and the high speed part of the rolling speed during rolling. It is a figure showing the influence which a rolling load has on the elongation difference of the board edge part with respect to the average value of a board width direction. It is a figure showing the influence which the work roll bender force exerts on the elongation difference of the board edge part with respect to the average value of a board width direction. It is a figure showing the influence which the intermediate roll bender force exerts on the elongation difference of the board edge part with respect to the average value of a board width direction. It is a figure showing the influence which the intermediate | middle roll shift position has on the elongation difference of the board edge part with respect to the average value of a board width direction. It is a figure showing the influence which the amount of material crowns has on the elongation difference of the board edge part to the average value of the board width direction. It is a figure which shows the detail of the conditions 1-condition 10 of FIG. It is a figure showing the relationship between a board edge part exit side tension | tensile_strength and the presence or absence of narrowing. It is a figure which shows the detail of the conditions 1-condition 10 of FIG. It is a figure showing the relationship between board edge part exit side tension | tensile_strength and the presence or absence of board fracture. It is a figure showing the relationship between a rolling speed and a friction coefficient. It is the schematic of the 6-high rolling mill and control system which were used in the Example.

  The inventors calculated the plate end portion exit side tension using a prediction formula representing the plate end portion exit side tension, and the narrowing limit over the entire rolling direction from the start to the end of the plate end exit side tension. By controlling the sheet end portion exit side tension by setting or correcting the control amount of the shape control means so as to be not less than the value and not more than the fracture limit value, the entire area in the rolling direction can be narrowed down from the start to the end of rolling. Various shape control methods that can prevent both plate breakage were investigated and investigated.

  As a result, paying attention to the fact that the plate end exit tension is almost linearly related to the average exit tension, rolling load, material crown amount, and control amount of the shape control means, the average exit side tension, rolling load, material crown amount And by controlling the control amount of the shape control means using a predictive equation that represents the tension at the end of the plate end using the control amount of the shape control means as a variable, the end tension at the end of the plate is rolled from the start to the end of rolling. It has been found that it is possible to set the value to be not less than the narrowing limit value and not more than the fracture limit value throughout the entire direction, and to prevent both narrowing and plate breakage throughout the entire rolling direction from the start to the end of rolling.

  Hereinafter, the shape control method of the present invention for a 6-roll mill having a work roll bender, an intermediate roll bender, and an intermediate roll shift as a shape control means installed in No. 3 stand of a cold tandem mill consisting of 4 stands. Of course, the present invention is similarly applied to a rolling mill other than a six-high rolling mill such as a rolling mill or a four-high rolling mill installed in another stand.

The plate end portion exit side tension Te is expressed by the sum of the average exit side tension Tav and the tension difference due to the rolling shape (difference between the plate end portion exit side tension and the average exit side tension) ΔT as shown in Equation (1). The
Te = Tav + ΔT (1)

Then, as is apparent from the principle of the shape detector that calculates the elongation difference in the plate width direction from the tension difference in the plate width direction, the Young's modulus is E, and the difference in elongation at the plate edge relative to the average value in the plate width direction. Assuming Δε, the tension difference ΔT due to the rolling shape is expressed by the equation (2).
ΔT = E · Δε · (−1) (2)

  Factors affecting the shape of the rolled material include the rolled material size, material, lubrication state, front / rear tension, rolling load, control amount of the shape control means, material crown amount, pre-rolling shape, and the like. Of these, regarding the rolled material dimensions, if the table is divided for each plate thickness and width, the influence of the change in the rolled material size in the section on the shape can be reduced. The material, lubrication state, and front / rear tension affect the shape of the rolled material, but most of the effect is caused by changes in roll deflection through the rolling load.

  In addition, when the rolling reduction is small as in skin pass rolling, the influence of the shape before rolling is large, but in normal cold rolling with a rolling reduction of 5% or more, the influence of the shape before rolling is small. Therefore, it can be said that the main factors affecting the shape change are the rolling load, the material crown amount, and the control amount of the shape control means.

  Therefore, the quantitative effects of the rolling load, the material crown amount, and the control amount of the shape control means on the rolling shape were examined. Here, the object controlled by the “shape control means” refers to a part or all of a roll bender, a roll shift, a rolling reduction / rolling load, a spot clarant, and the like.

  FIG. 2 shows the influence of the rolling load P (kN) on the elongation difference Δε at the plate edge with respect to the average value in the plate width direction. A change in rolling load appears as a change in roll deflection, and changes the shape of the rolled material. The relationship between the rolling load and the amount of roll deflection is almost linear since it is intended for deformation in the elastic region. Therefore, the elongation difference Δε at the plate end with respect to the average value in the plate width direction is also linearly related to the rolling load P.

  FIG. 3 shows the influence of the work roll bender force Wb (kN) on the elongation difference Δε at the plate end with respect to the average value in the plate width direction. Since the work roll bender, which is a shape control means, changes the rolling shape by changing the roll deflection in the same manner as the rolling load, the difference in elongation at the plate end with respect to the average value in the work roll bender force Wb and the plate width direction. There is also a linear relationship with Δε.

  FIG. 4 shows the influence of the intermediate roll bender force Ib (kN) on the elongation difference Δε at the plate end with respect to the average value in the plate width direction. The intermediate roll bender also changes the rolling shape by changing the roll deflection in the same manner as the rolling load. Therefore, there is also a linear relationship between the intermediate roll bender force Ib and the elongation difference Δε at the plate end with respect to the average value in the plate width direction.

  FIG. 5 shows the influence of the intermediate roll shift position Ls (mm) on the elongation difference Δε at the plate end with respect to the average value in the plate width direction. The intermediate roll shift position is defined by the distance from the taper start point to the plate end. The case where the taper start point is inside the plate end is negative, and the case where the taper start point is outside is positive. The intermediate roll shift also changes the rolling shape by changing the roll deflection by changing the contact pressure distribution between the work roll and the intermediate roll. Therefore, the intermediate roll shift position Ls and the elongation difference Δε at the plate end with respect to the average value in the plate width direction are also in a linear relationship.

  FIG. 6 shows the influence of the material crown amount Cr (μm) on the elongation difference Δε at the plate end with respect to the average value in the plate width direction. The amount of material crown was defined by the difference in plate thickness between the plate edge and the plate width center. As a result, it was found that the material crown amount Cr and the elongation difference Δε at the plate end with respect to the average value in the plate width direction also have a linear relationship.

From the relationship between the above factors, the elongation difference Δε at the plate edge with respect to the average value in the plate width direction can be expressed by Equation (3) using ae, be, ce, de, ee, and fe as influence coefficients. .
Δε = ae · P + be · Cr + ce · Wb + de · Ib + ee · Ls + fe (3)

  The influence coefficients ae, be, ce, de, ee, and fe are constants determined by the production type such as the plate width, plate thickness, and material, and are combined with the experiment or the elastic deformation analysis of the roll and the plastic deformation analysis of the material. It is obtained from the simulation by the analysis model. Each influence coefficient is set in a table for each section such as a plate width, a plate thickness, and a material, or expressed as a function as a function of the plate width, the plate thickness, the material, and the like.

  Specifically, each influence coefficient includes: ae: slope of a straight line representing the relationship between rolling load and elongation difference (see FIG. 2); be: slope of a straight line representing the relationship between the amount of material crown and elongation difference (FIG. 6). See), ce: slope of a straight line representing the relationship between work roll bender force and elongation difference (see FIG. 3), de: slope of a straight line representing the relationship between intermediate roll bender force and elongation difference (see FIG. 4), ee : Slope of a straight line representing the relationship between the intermediate roll shift position and elongation difference (see FIG. 5), fe: constant term.

  In a typical 6-high rolling mill having a work roll diameter of about 400 mm, a general 20-high rolling mill having a work roll diameter of 100 mm or less, and the like, the work roll is likely to be greatly deformed. Therefore, although the influence of the rolling load on the shape of the rolled material is large, the influence of the material crown amount on the shape of the rolled material tends to be small. In this case, in Equation (3), the material crown amount Cr can be set to zero, and the influence term of the material crown amount can be ignored.

From Equations (1) to (3), a prediction equation representing the plate end portion exit side tension with the average exit side tension, rolling load, material crown amount and control amount of the shape control means as variables is expressed by Equation (4). .
Te = Tav−E (ae · P + be · Cr + ce · Wb + de · Ib + ee · Ls + fe) (4)

  Next, the relationship between the plate end portion exit side tension and the presence or absence of narrowing in the plate thickness of 0.3 mm to 0.5 mm and the plate width of 850 mm to 1050 mm on the tandem mill exit side was investigated. In FIG. 7, each parameter (rolling load, material crown amount, average delivery tension, work roll bender force, intermediate roll bender force, intermediate roll shift position) is set for each rolling condition (condition 1 to condition 10). Yes. Therefore, the predicted value of the plate end portion exit side tension was calculated according to the above formula (4) for each condition, and the presence or absence of narrowing was investigated.

  The result is shown in FIG. As shown in FIG. 8, no narrowing occurred under conditions 1 to 5, but narrowing occurred under conditions 6 to 10. That is, it has been found that a narrowing limit value exists in the plate end portion exit side tension, and that narrowing occurs when the plate end portion exit side tension is equal to or less than the narrowing limit value. In this manner, the predicted value of the plate end portion exit side tension can be obtained from each condition and Expression (4), and it can be predicted whether or not narrowing will occur from the obtained predicted value.

  In other words, if the control amount of the shape control means is set or corrected so that the plate end exit tension calculated by the equation (4) is equal to or greater than the narrowing limit value over the entire rolling direction from the start to the end of rolling, It is possible to prevent narrowing down over the entire rolling direction from the start to the end of rolling.

  Similarly to the case of FIG. 8, the relationship between the plate end portion exit side tension and the presence or absence of plate breakage in the plate thickness of 0.3 mm to 0.5 mm and the plate width of 850 mm to 1050 mm on the tandem mill exit side was investigated. In FIG. 9, each parameter (rolling load, material crown amount, average delivery tension, work roll bender force, intermediate roll bender force, intermediate roll shift position) is set for each rolling condition (condition 1 to condition 10). Yes. Therefore, the predicted value of the plate end portion exit side tension was calculated according to the above formula (4) for each condition, and the presence or absence of plate breakage was investigated.

  The result is shown in FIG. As shown in FIG. 10, plate breakage did not occur under conditions 1-5, but plate breakage occurred under conditions 6-10. That is, as shown in FIG. 10, it has been found that there is a breaking limit value in the plate end portion exit side tension, and that the plate end breakage occurs when the plate end portion exit side tension is equal to or greater than the break limit value. Thus, the predicted value of the plate end portion exit side tension can be obtained from each parameter and the equation (4), and it can be predicted from the obtained predicted value whether or not the plate breaks.

  In other words, if the control amount of the shape control means is set or corrected so that the plate end exit side tension calculated by the equation (4) is equal to or less than the fracture limit value over the entire rolling direction from the start to the end of rolling, It is possible to prevent plate breakage over the entire rolling direction from the start to the end of rolling.

  From the above results, the shape control means controls so that the plate end portion exit side tension calculated by the equation (4) is not less than the narrowing limit value and not more than the fracture limit value in the entire rolling direction from the start to the end of rolling. By setting or correcting the amount, it is possible to prevent both narrowing and sheet breakage throughout the entire rolling direction from the start to the end of rolling.

  By the way, as a result of investigating the relationship between the rolling speed and the friction coefficient, as shown in FIG. 11, the influence of the friction coefficient on the rolling speed is small in the high speed range, but the friction coefficient increases with the reduction of the rolling speed in the low speed range. I understood it. That is, it can be said that there is a correlation between the rolling speed and the friction coefficient.

  In the initial setting of the shape control means, the rolling load P is predicted based on the relationship between the rolling speed and the friction coefficient obtained in FIG. 11 using rolling load formulas such as the Brand & Ford formula, the Hill formula, etc. Substituting the side tension Tav, the rolling load prediction value P, and the material crown measurement value Cr into the prediction formula (4) representing the plate end portion exit side tension Te, and the plate end portion exit side tension Te is equal to or greater than the narrowing limit value, and The work roll bender force Wb, the intermediate roll bender force Ib, and the intermediate roll shift position Ls are calculated and set so as to be equal to or less than the breaking limit value.

  In the shape control of the rolled material during rolling, the rolling load P is continuously predicted according to the change of the rolling speed based on the relationship between the rolling speed and the friction coefficient obtained in FIG. Substituting Tav, rolling load predicted value P and material crown measured value Cr into prediction formula (4) representing the sheet end exit side tension Te, the sheet end exit side tension Te is equal to or greater than the narrowing limit value and the fracture limit value The work roll bender force Wb, the intermediate roll bender force Ib, and the intermediate roll shift position Ls are calculated and corrected so as to be as follows.

  Further, in the constant speed region of the low speed part of the rolling speed at the start and end of rolling and the high speed part of the rolling speed during rolling, the rolling load P is continuously measured, and the average delivery side tension Tav and the measured values of the rolling load are measured. The measured value Cr of P and the material crown is substituted into the prediction formula (4) representing the plate end exit side tension Te, and the work roll is set so that the plate end exit side tension Te is not less than the narrowing limit value and not more than the fracture limit value. If the bender force Wb, the intermediate roll bender force Ib, and the intermediate roll shift position Ls are calculated and corrected, the shape control accuracy in a constant speed region is improved.

  The target value of the plate end portion exit side tension Te is not less than the narrowing limit value and not more than the fracture limit value, but the plate end portion exit side tension Te is predicted to be close to the average value of the narrowing limit value and the fracture limit value. If the value is set or corrected, even if the plate end portion exit side tension Te deviates from the predicted value due to a disturbance factor or the like, it tends to be more than the narrowing limit value and less than the fracture limit value. It is possible to prevent both narrowing and plate breakage.

  In the above description, it is assumed that the control amounts of the three shape control means of the work roll bender, the intermediate roll bender, and the intermediate roll shift are set or corrected. However, the combination of the shape control means to be used is the work roll bender, the intermediate roll bender. It is not limited to a combination of a roll bender and an intermediate roll shift. Even in a 6-high rolling mill having a work roll bender, an intermediate roll bender and an intermediate roll shift as shape control means, the shape control during rolling is responsive. The control amounts of the two shape control means of the work roll bender and the intermediate roll bender excluding the bad intermediate roll shift may be corrected. In this case, the intermediate roll shift position Ls is fixed to the initial set value in the equation (4).

  Further, when the shape control means is only a work roll bender as in the case of a four-high rolling mill, the formula (5) is used instead of the formula (4), and the plate end portion exit side tension Te is equal to or more than the narrowing limit value and the fracture occurs. The work roll bender force Wb is calculated so as to be equal to or less than the limit value, and is set or corrected.

  Te = Tav−E (ae · P + be · Cr + ce · Wb + fe) (5)

  When rolling a cold-rolled steel sheet 500 coil having a thickness of 0.3 mm to 0.5 mm on the tandem mill outlet side in a 6-high rolling mill installed in No. 3 stand of a cold tandem mill consisting of 4 stands, the present invention An example in which is applied will be described.

  As shown in FIG. 12, the six-high rolling mill 1 includes a work roll bender 2, an intermediate roll bender 3, and an intermediate roll shift 4 as shape control means. The host computer 5 has in advance rolling conditions (for example, the rotation speed of the work roll, the work roll diameter, the relationship between the rolling speed and the friction coefficient, the plate width, the input / output side plate thickness, the average input / output side tension, the deformation resistance of the rolled material, etc.). The rolling load P is calculated according to the rolling load equation based on the relationship between the rolling speed and the friction coefficient obtained in FIG.

  The process computer 6 captures the influence coefficient (ae, be, ce, de, ee, fe) and the measured value of the material crown Cr that are calculated in advance for each of the plate width, plate thickness, and material classification, and the plate edge exit side The work roll bender force Wb, the intermediate roll bender force Ib, and the intermediate roll shift position Ls so that the plate end portion exit side tension Te is an average value of the narrowing limit value and the breaking limit value in the prediction formula (4) representing the tension Te. Was calculated and initialized. In addition, the value calculated | required in FIG. 8 was employ | adopted about the narrowing-down limit value, and the value calculated | required in FIG. 10 was employ | adopted about the fracture limit value.

  Moreover, after rolling starts, the rolling load P is continuously calculated according to the change of the rolling speed based on the relationship between the rolling speed and the friction coefficient obtained in FIG. The work roll bender force Wb and the intermediate roll bender force Ib were calculated and corrected so that the plate end portion exit side tension Te was an average value of the narrowing limit value and the breaking limit value in the formula (4). The intermediate roll shift position Ls was fixed at an initial set value.

  Moreover, in the constant speed area | region of the low-speed part of the rolling speed at the time of rolling start and completion | finish, and the high-speed part of the rolling speed during rolling, the rolling load P is measured continuously and the prediction formula (T) In 4), the work roll bender force Wb and the intermediate roll bender force Ib were calculated and corrected so that the plate end exit side tension Te would be an average value of the narrowing limit value and the breaking limit value.

  As a result, conventionally, when 500 coils were squeezed with 2 coils, plate breakage occurred with 3 coils, but as a result of applying the method of the present invention, neither squeezing nor plate breakage occurred with 500 coils.

  In this way, the plate end portion exit side tension is calculated using a prediction formula representing the plate end portion exit side tension, and the calculated plate end portion exit side tension is limited over the entire rolling direction from the start to the end of rolling. From the start to the end of rolling between the stands of the cold tandem mill, by controlling the tension at the edge of the plate end by setting or correcting the control amount of the shape control means so that it is greater than the value and less than the fracture limit value It is possible to prevent both narrowing and sheet breakage throughout the entire rolling direction.

1: Six-high rolling mill 2: Work roll bender 3: Intermediate roll bender 4: Intermediate roll shift 5: Upper computer 6: Process computer 7: Load meter 8: Rolled material 9: Work roll 10: Intermediate roll 11: Backup roll

Claims (4)

Squeezing limit value of the sheet end portion exit side tension that causes the rolling material to squeeze, the rupture limit value of the sheet end portion exit side tension that causes the plate breakage of the rolled material, and the correlation between the rolling speed and the friction coefficient in advance,
Create a prediction formula representing the plate end portion exit side tension in advance,
Calculate the control amount of the shape control means so that the sheet end portion exit side tension calculated by the prediction formula at the start of rolling of the rolled material is not less than the narrowing limit value and not more than the fracture limit value,
After setting the calculated control amount as the control amount of the shape control means, the rolling load is continuously predicted according to the change in the rolling speed based on the correlation between the rolling speed and the friction coefficient, and the prediction formula Recalculate the control amount of the shape control means so that the plate end portion exit side tension calculated by the above is not less than the narrowing limit value and not more than the fracture limit value,
The shape control method in cold rolling, wherein the sheet end portion exit side tension is controlled by correcting the recalculated control amount as a control amount of the shape control means. Squeezing limit value of the sheet end portion exit side tension that causes the rolling material to squeeze, the rupture limit value of the sheet end portion exit side tension that causes the plate breakage of the rolled material, and the correlation between the rolling speed and the friction coefficient in advance,
Preliminarily creating a prediction formula representing the sheet end portion exit side tension with the average exit side tension, rolling load and control amount of the shape control means as variables,
When the rolling start of the rolled material, the average exit side tension and the predicted value of the rolling load are substituted into a prediction formula representing the plate end part exit side tension, and the plate end part exit side tension is equal to or more than a narrowing limit value, and Calculate the control amount of the shape control means so that it is below the fracture limit value,
After setting the calculated control amount as a control amount of the shape control means, based on the correlation between the rolling speed and the friction coefficient, predicting the rolling load continuously according to the change of the rolling speed,
Substituting the average exit side tension and the predicted rolling load into the prediction formula, and calculating the control amount of the shape control means so that the exit end tension on the plate end is not less than the narrowing limit value and not more than the fracture limit value. And
The shape control method in cold rolling characterized by controlling the sheet end portion exit side tension by correcting the calculated control amount to the control amount of the shape control means. Squeezing limit value of the sheet end portion exit side tension that causes the rolling material to squeeze, the rupture limit value of the sheet end portion exit side tension that causes the plate breakage of the rolled material, and the correlation between the rolling speed and the friction coefficient in advance,
Preliminarily creating a prediction formula representing the plate end portion exit side tension with the average exit side tension, rolling load, material crown amount and control amount of the shape control means as variables,
At the start of rolling of the rolled material, the average exit side tension, the predicted value of the rolling load, and the material crown amount are substituted into the prediction formula, and the plate end exit side tension is equal to or greater than the narrowing limit value and fracture Calculate the control amount of the shape control means to be below the limit value,
After setting the calculated control amount as the control amount of the shape control means, predicting the rolling load continuously according to the change of the rolling speed based on the correlation between the rolling speed and the friction coefficient,
Substituting the average exit side tension, the predicted rolling load and the material crown amount into the prediction formula, and the shape control means so that the exit end tension of the plate end portion is not less than the narrowing limit value and not more than the fracture limit value. Control amount of
The shape control method in cold rolling characterized by controlling the sheet end portion exit side tension by correcting the calculated control amount to the control amount of the shape control means. Further, the rolling load was continuously measured in the constant speed region of the low speed part of the rolling speed at the start and end of rolling of the rolled material and the high speed part of the rolling speed during rolling, and calculated by the prediction formula The shape control method in cold rolling according to any one of claims 1 to 3, wherein the strip end side tension is controlled by using the measured rolling load instead of the predicted value of the rolling load.