JPH10277616A - Rolling torque control method and rolling torque control device for hot rolling - Google Patents

Abstract

PROBLEM TO BE SOLVED: To predict the rolling torque with a high precision, and to improve the working efficiency of a rolling mill be predicting the temperature distribution of the surface of a plate at the time of rolling from the temperature distribution of the surface of the plate before rolling, predicting the rolling torque according to this predicted value, and correcting the rolling torque by the change of the roll crown of a rolling roll and the change of the plane shape of the plate at the time of rolling. SOLUTION: With a temperature detecting part 3 taking out detected data from a heating furnace 2, etc., the temperature distribution of the surface of the plate 5 before rolling is found. With a roll crown detecting part 10, the roll crowns of upper and lower work rolls 18, 19 are found. According to the data of the temperature detecting part 3, the temperature distribution of the surface of the plate at the time of rolling, is predicted with a prescribed formula by an arithmetic processing part 12. Next, according to detected data found by the roll crown detecting part 10, a calculation is performed again with a prescribed formula, and the predicted value of the rolling torque in a required pass is corrected. According to the data of a plate shape detecting part 6, the predicted value of the rolling torque is corrected by recalculating with a prescribed formula, if necessary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling a rolling torque in hot rolling and a rolling torque control device used for the control.

[0002]

2. Description of the Related Art When setting a rolling pass schedule in hot rolling, a rolling torque can be obtained based on a desired rolling speed. This includes an upper limit of a generated torque of a rolling motor, a spindle, a coupling and the like. Since a constraint such as an upper limit on the strength is imposed in the above, a limit torque is calculated in consideration of these constraints, and a rolling pass schedule is assembled based on the limit torque.

[0003] In order to increase the operating efficiency of a rolling mill and to obtain high productivity, it is necessary to accurately predict the rolling torque. Various calculations were performed by regarding the temperature deviation, rolling load, steel sheet shape, roll crown, and the like as constant conditions. However, in actual rolling, a temperature deviation occurs in the surface of the steel sheet, which causes a change in deformation resistance, that is, a change in rolling load, and as shown in FIG. 4, this affects the rolling torque. There was that.

[0004] In addition, a change in the shape of a steel sheet during rolling, such as a dog bone shape, when edging, thickness difference width or the like is performed, may affect the rolling torque as shown in FIG. there were. Further, when the roll crown changes due to thermal expansion, abrasion, or the like of the rolling roll, the rolling torque is affected to a considerable extent as shown in FIG.

[0005] For this reason, the prediction accuracy of the rolling torque is inevitably low, and the prediction result and the rolling result may be greatly different.

[0006]

Conventionally, the performance of the rolling motor, the strength of the spindle and the coupling, and the like have reached their upper limits in consideration of the fact that the prediction accuracy of the rolling torque varies as described above. Nevertheless, from the viewpoint of emphasizing equipment protection, the safety factor was set to be excessively large and the above-mentioned limit torque was determined to be low.

[0007] Therefore, the fact is that the processing capacity of the rolling mill has not been fully utilized. The present invention has been made in view of the above circumstances, and makes it possible to accurately and highly accurately predict a rolling torque, thereby making full use of the capacity of a rolling mill and increasing its operating efficiency. It is an object of the present invention to provide a method and a control device for controlling a rolling torque of hot rolling that enable high productivity.

[0008]

According to the present invention, the following technical measures have been taken in order to achieve the above object. That is, in the rolling torque control method of hot rolling according to the present invention, the temperature distribution of the steel sheet surface before rolling is obtained by calculation or measurement, and the temperature distribution of the steel sheet surface during rolling is predicted from this, and this predicted value is calculated. The rolling torque is predicted by calculating the average deformation resistance of the steel sheet based on the above, the roll crown change of the rolling roll is predicted by calculation or measurement, the predicted value of the rolling torque is corrected based on this predicted value, In this case, the change in the plane shape occurring in the steel sheet is calculated or measured to correct the rolling torque of the corresponding pass.

In order to obtain the temperature distribution of the steel sheet surface before rolling, a method of calculating the temperature distribution at the time of heating and extracting the steel sheet or a method of measuring the temperature at a plurality of points on the steel sheet surface immediately before rolling is used. Etc. The roll crown change of the rolling roll can be obtained by a method of calculating an initial crown, a thermal crown, a roll crown in consideration of a wear profile, a method of measuring a roll profile, or the like.

[0010] The change in the planar shape of the steel sheet at the time of rolling can be obtained by a method using a flat shape meter or an edge profile meter, or by judging from rolling conditions. As described above, since the rolling torque is predicted while first considering the temperature distribution of the steel sheet surface before rolling, it is possible to flexibly cope with a change in deformation resistance (a change in rolling load). In addition, since the rolling torque is corrected by the change in the roll crown of the rolling roll or the change in the planar shape of the steel sheet during rolling, the roll crown changes due to the thermal expansion or wear of the rolling roll, and the edging and thickness difference. This makes it possible to flexibly cope with a change in the shape of the steel sheet during rolling when tentering or the like is performed, and the predicted value of the rolling torque and the rolling torque during actual rolling can be approximated or matched with high accuracy.

Therefore, it is possible to set the rolling torque constraint to the maximum capacity of the rolling mill, and high productivity can be realized. Further, in the rolling torque control device for hot rolling according to the present invention, a temperature detection unit for determining the temperature distribution of the steel sheet plate surface before rolling, a roll crown detection unit for determining the roll crown of the rolling roll, and a steel plate during rolling. It has a steel sheet shape detecting section for determining the resulting change in plane shape, and an arithmetic processing section which controls these detecting sections.

The arithmetic processing unit predicts the rolling torque by sequentially calculating the temperature distribution of the steel sheet surface during rolling and the average deformation resistance of the steel sheet based on the detection data from the temperature detecting unit, and detects the roll crown. The rolling torque is corrected based on the detection data from the section, and the rolling torque is further corrected for each required pass based on the detection data from the steel sheet shape detecting section. The control method can be implemented.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 schematically shows a rolling torque control device 1 according to the present invention. The rolling torque control device 1 includes a temperature detection unit 3 for extracting required detection data from the heating furnace 2 and the like, a steel plate shape detection unit 6 for extracting required detection data from the steel plate 5 during rolling, and a required It has a roll crown detection unit 10 for extracting detection data, and an arithmetic processing unit 12 capable of controlling the detection units 3, 6, and 10.

The temperature detector 3 determines the temperature distribution on the steel sheet surface before rolling. In this method, heating furnace 2
There is a method of calculating the temperature distribution on the steel sheet surface when the steel sheet is heated and then extracted. For this calculation, a temperature simulation by a difference method in a computer or a simple expression can be used (for example, Japanese Patent No.
No. 54414).

As another method for obtaining the temperature distribution on the steel sheet surface before rolling, a plurality of points on the steel sheet surface are actually measured immediately before rolling using a scanning thermometer, a thermoviewer, or the like. There are methods. The steel sheet shape detection unit 6 obtains a change in the planar shape that occurs in the steel sheet 5 by performing edging by the edger 14 and setting a thickness difference (MAS rolling method or DBR method) during rolling. In this way,
Measuring instruments 1 such as a plane shape meter and an edge profile meter
There is a method of performing measurement by using 5 and 16.

Further, as another method for determining the change in the planar shape occurring in the steel sheet 5, various rolling conditions such as a rolling size, a rolling load, a rolling reduction, a roll profile, a steel sheet temperature, a deformation resistance, and an edging amount are also used. At the same time, the shape of the steel sheet (the planar shape of the top, bottom, and edge portions of the steel sheet) is calculated by a large deformation analysis (rigid plastic FEM), or the large deformation analysis is formulated and predicted by a simple expression (regression equation). Alternatively, a method of judging from the result or the like can be adopted.

The roll crown detector 10 determines the roll crown of the rolling roll (actually, the upper and lower work rolls 18 and 19). This roll crown may be calculated by an appropriate roll crown prediction formula in consideration of an initial crown, a thermal crown, and a wear profile. Further, as another method for obtaining the roll crown of the rolling roll, a method of measuring a roll profile by arranging a large number of laser distance meters in the width direction can be adopted.

The arithmetic processing section 12 first predicts the temperature distribution of the steel sheet surface during rolling by equation (1) based on the detection data obtained by the temperature detecting section 3.

[0019]

(Equation 1)

Then, based on the predicted temperature distribution, the average deformation resistance of the steel sheet for each pass is calculated by equation (2).

[0021]

(Equation 2)

Next, from the average deformation resistance thus obtained, a rolling torque for each pass is predicted by the equation (3).

[0023]

(Equation 3)

Next, based on the detection data obtained by the roll crown detecting section 10, the above equation (3) is recalculated to correct the predicted value of the rolling torque in a required pass. Further, if necessary, the above formula (3) is recalculated based on the detection data obtained by the steel sheet shape detection unit 6, and the predicted value of the rolling torque is corrected in a required pass.

The rolling torque control method of the present invention performed by using the rolling torque control device 1 having the above-described configuration will be described below with reference to a flowchart. That is,
As shown in FIG. 1, first, the temperature distribution of the steel sheet surface before rolling is obtained, and then the temperature distribution of the steel sheet surface during rolling is predicted, and the average deformation resistance of the steel sheet is calculated based on the predicted value. Predict torque (Step 10)
0).

Next, the roll crown change of the rolling roll is predicted (step 101), and the predicted value of the rolling torque is corrected based on the predicted value (step 102). Further, a change in the planar shape occurring in the steel sheet during rolling is obtained (step 103), and the rolling torque of the corresponding pass is corrected as necessary (step 104).

[0027]

[Embodiment] When the rolling torque is predicted by the rolling torque control method of the present invention (hereinafter simply referred to as "the present invention method").
And the case where the rolling torque was predicted by the conventional method (hereinafter, simply referred to as “conventional method”) was compared with the result of actual measurement of the rolling torque at the time of actual rolling to check their prediction accuracy.

The steel plate used was SS400. The outer dimensions of the steel sheet material before rolling are 235 mm in thickness and 177 in width.
0 mm and length 2900 mm. The rolling mill 9 used had a maximum allowable load of 5000 ton class. The work rolls 18 and 19 have an outer diameter of 950 mm and a body length of 4800 mm, and the backup rolls 20 and 21 have an outer diameter of 1980 m.
m, body length 4800 mm.

The rolling conditions were as follows: the set amount of reduction was 215 mm, and the rolling speed was 42 rpm. The actual measurement of the rolling torque during rolling was performed by attaching a strain gauge to the spindle. FIG. 3 is a graph summarizing the above-mentioned investigation results. In contrast to the transition (average is 311 ton-m) when the rolling torque is actually measured, the predicted rolling torque by the method of the present invention is 305 ton-m. It is obvious that they match.

On the other hand, the predicted value of the rolling torque according to the conventional method is 253 ton-m, which indicates that there is a large difference from the measured value of the rolling torque. On the other hand, in order to examine how much the prediction accuracy (actual value / predicted value) varies between the method of the present invention and the conventional method, 20
Zero rolling was performed. As a result, as shown in the following table, the value was 0.25 in the conventional method, whereas it was 0.15 in the method of the present invention.
9, which indicates that the prediction accuracy of the method of the present invention is excellent.

[0031]

[Table 1]

From the above, when the fatigue limit affecting the fatigue resistance of the rolling mill 9 is set to 320 ton-m in both the method of the present invention and the conventional method, and the frequency exceeding this is assumed to be equivalent, The torque constraint at the time of determining the rolling pass schedule was 280 ton-m in the conventional method, but could be increased to 300 ton-m in the method of the present invention.

That is, in the method of the present invention, the number of rolling passes can be reduced by about 1 pass / roll on average, and the productivity can be increased accordingly.

[0034]

As apparent from the above description, the method and apparatus for controlling the rolling torque of hot rolling according to the present invention include:
Since the rolling torque is predicted by first considering the temperature distribution of the steel sheet surface before rolling, not only can it flexibly cope with fluctuations in deformation resistance (fluctuations in rolling load),
Thereafter, since the rolling torque is corrected by the roll crown change of the rolling roll and the change in the planar shape of the steel sheet at the time of rolling, the predicted value of the rolling torque and the rolling torque at the time of actual rolling are approximated or substantially matched with each other with high precision. be able to.

Therefore, the rolling torque constraint can be set to the maximum capacity of the rolling mill, and high productivity can be realized.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a rolling torque control method according to the present invention.

FIG. 2 is a block diagram showing a rolling torque control device according to the present invention.

FIG. 3 is a graph comparing the rolling torque at the time of predicting the rolling torque according to the method of the present invention and the rolling torque at the time of predicting the rolling torque according to the conventional method with the rolling torque at the time of actual rolling.

FIG. 4 is a graph showing that a temperature distribution generated on a steel sheet surface affects a rolling torque.

FIG. 5 is a graph showing that a change in a planar shape generated on a steel sheet affects a rolling torque.

FIG. 6 is a graph showing that a roll crown change occurring in a rolling roll affects a rolling torque.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rolling torque control apparatus 2 Heating furnace 3 Temperature detection part 5 Steel plate 6 Steel plate shape detection part 9 Rolling mill 10 Roll crown detection part 12 Operation processing part

Claims (2)

[Claims] 1. A method for calculating or measuring a temperature distribution of a steel sheet surface before rolling by calculating or measuring a temperature distribution of the steel sheet surface during rolling, and calculating an average deformation resistance of the steel sheet based on the predicted value. The rolling torque is predicted by calculation, the roll crown change of the rolling roll is predicted by calculation or measurement, and the predicted value of the rolling torque is corrected based on the predicted value, and the change in the plane shape that occurs in the steel sheet during rolling is calculated or measured. A rolling torque control method for hot rolling, wherein the rolling torque of a corresponding pass is determined by the following method. 2. A temperature detecting unit (3) for obtaining a temperature distribution on a steel sheet surface before rolling, and a roll crown detecting unit (10) for obtaining a roll crown of a rolling roll (18, 19).
And a steel sheet shape detecting section (6) for determining a change in the planar shape of the steel sheet (5) during rolling, and each of these detecting sections (3, 10,
6) that controls the temperature distribution of the steel sheet surface during rolling based on the detection data from the temperature detection unit (3). The rolling torque is predicted by sequentially calculating the average deformation resistance of the steel sheet, and the predicted value of the rolling torque is corrected based on the detection data from the roll crown detecting unit (10). A rolling torque control device for hot rolling, wherein the rolling torque is further corrected for each required pass based on detection data.