JPH0475714A - Method for controlling top end sheet thickness of hot continuous rolling mill - Google Patents

Abstract

PURPOSE:To execute the optimum draft correction and to obtain the satisfactory sheet thickness form the top end of the hot strip by correcting the position of roll reduction against the rolling load at the top end part of the material to be rolled with searching the ratio of the rolling force on the stationary art and based on this ratio. CONSTITUTION:When the top 8A of the material to be rolled is bitten with the work roll 10 of the i-th stand, the rolling load deviation Pti of the top art 8A of the material to be rolled at the i-th stand is detected by the load meter 14 of the i-th stand. When the time of the normal art to be rolled 8B of the material to be rolled which an be measured with the thickness meter 20 and the thermometer 22 is arrived at the i-th stand, the rolling load Pmi of the normal part 8B at the i-th sand is detected by the load meter 14, when the time of the position for detecting the load of the normal part 8B passes throught the thickness meter 20 and the thermometer 22, the outlet side sheet thickness deviation hmi and the surface temperature deviation Tsim are detected. The loading variation P. smi against the predicated rolling load at the normal part 8B is found. The rolling reduction position of the j-th stand is corrected by Stj, before the material to be rolled is bitten in with the j-th stand.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for controlling the tip plate thickness of a hot rapid continuous rolling mill,
In particular, the present invention relates to a plate thickness control method that allows a desired thickness to be obtained from the tip of the Horatos 1-lip. [Prior Art] In order to obtain the target thickness from the tip of the hollow strip, it is necessary to set the rolling position (roll gap) of each stand of the hot rapid rolling mill to an appropriate value. be. The rolling position of each stand is often set by a computer based on rolling theory formulas (rolling load formula, deformation resistance formula, gauge meter formula, etc.). However, there are problems with the accuracy of the rolling theoretical formula itself, and there is a WA difference in the input values required for calculation (for example, the surface temperature of the rolled material on the finishing entry side), so it is difficult to find the optimal rolling reduction. Setting is not always done and it is difficult to get good thickness from the tip of the hot strip. Therefore, in order to obtain a good thickness from the tip of the strip, the rolling position of each stand must be adjusted to the optimum value (
Needs to be fixed. Therefore, for example, Japanese Patent Laid-Open No. 59-144510 proposes a method in which a thickness gauge is installed between stands and the reduction amount or rolling load is corrected and controlled based on the detected thickness deviation of the material to be rolled.

[Problem to be solved by the invention 1] However, in an unsteady rolling region such as the leading edge of hot slip, rolling becomes unstable due to poor plate thickness measurement accuracy and tension fluctuations. In some cases, the conventional plate thickness control method that corrects the roll reduction position based on the plate thickness difference detected between stands does not allow for optimal reduction correction, and it is difficult to obtain the target plate thickness from the tip of the coil. was difficult. The present invention has been made in order to solve the above-mentioned conventional problems, and is to control the plate thickness at the tip of a hot continuous rolling mill that can obtain a good plate thickness from the tip of the hot strip, which is an unsteady rolling area. The purpose is to provide a method. [Means for Solving the Problems] The present invention provides a method for controlling plate thickness at the tip end of a continuous hot rolling mill, in which a thickness gauge and a thermometer are installed on the exit side of at least one stand other than the last stand, and Immediately after the material is bitten into the i-th stand rolling mill immediately before the installation location of the thickness gauge and thermometer, the rolling load at the tip of the material to be rolled is detected, and then the rolling load at the tip of the material to be rolled is detected. The side plate thickness, surface temperature and rolling load are detected, and the ratio of the rolling load at the tip of the rolled material at the i-th stand to the rolling load at the steady rolling section is calculated, and along with the calculated value, the plate thickness and surface at the steady rolling section are calculated. The above object has been achieved by correcting the rolling position of the j-th stand in which the material to be rolled has not yet been bitten, based on the temperature.

[Action and effect]

In the present invention, the ratio of the rolling load in the stationary part of the rolled material where the plate thickness and surface temperature can be accurately detected to the rolling load that can be detected accurately even at the tip of the rolled material is determined, and based on this ratio, Since the rolling position is corrected, the rolling reduction of the continuous hot rolling mill can be optimally corrected, and a good plate thickness can be obtained from the tip of the hot strip, which is an unsteady rolling region. Embodiment 1 An embodiment of the present invention will be described in detail below with reference to the drawings. The configuration of a continuous hot rolling mill consisting of an fWA stand to which the present invention is applied is as shown in FIG. Each stand of this continuous rolling mill includes a work roll 10 for rolling the material to be rolled (hot strip) 8, a backup roll 12 for reinforcing the work roll 10, and a device for detecting the rolling load via the backup roll 12. a load cell 14 for the purpose of this, and a rolling position detection device (also serving as a rolling position control device) for detecting the rolling position of the work roll 10.
16 are mainly provided. Furthermore, a thickness gauge 20 and a thermometer 2 for implementing the present invention
2 is installed, for example, on the exit side of the i-th stand. In the figure, 30 is a computer for performing control according to the present invention. Hereinafter, with reference to FIG. 1, the control procedure for each rolling stand according to this embodiment will be explained in detail. First, in step 110, immediately after the tip 8A of the rolled material 8 is bitten by the work roll 10 of the i-th stand, the load meter 14 of the i-th stand calculates the rolling load Pt1 ( or rolling load deviation ΔP
t1) is detected. Next, when the steady rolling portion 8B of the rolled material whose measurement accuracy can be guaranteed by the thickness gauge 20 and the thermometer 22 reaches the i-th stand, in accordance with step 120, the load meter 14 measures the steady state of the rolled material at the i-th stand. The rolling load Pmi of the section 8B is detected, and when the load detection position of the steady section 8B passes the thickness gauge 20 and thermometer 22 installed on the exit side of the i-th stand, the tapped plate thickness hmi ( Or outlet side plate thickness deviation Δt1m+> and rolled material surface concentration Ts
mi (or surface temperature deviation ΔTsmi) is detected. Next, the process proceeds to step 130, where the steady portion 8 of the rolled material in the j-th stand downstream from the i-th stand is calculated using the following formula.
The load variation ΔPrnj with respect to the predicted rolling load at B is determined. ΔPm; = (aP; /ah i ) (1
1 m i h o i ) + (a
P/2)T)((aT,;/aTo i) ・Tsmi To,i) =(
1) Here, hoI is the target exit side plate thickness of the first stand,
The lower 0.1 is the target rolling temperature of the J stand, (aPj/
ahi> is the first force exerted on the rolling load P of the first stand.
Influence coefficient of stand exit plate thickness hi, (aP/aT>, H114j Stand (7) pressure m?J
The weight P1 is the rolling temperature T of the 1-th stand, the influence coefficient of i, and (aTJ/aToi> is the rolling temperature Tj of the J-th stand.
This is the influence coefficient of the surface temperature Toj of the rolled material on the exit side of the first stand. On the other hand, in step 140, the ratio Cfi of the actual rolling loads of the tip end portion 8A and the steady rolling portion 8B in the first stand is determined as shown by the following equation. Cr 1=Pt i/Pm i ・=
(2) Then, at the tip 8A of the rolled material, in steps 150 and 160, before the rolled material is bitten by the j-th stand, ΔS1 calculated using the following formula
Correct the lowering position of the j-th stand by 4. Δ5tj=G, i・1/M; (Cri(P o j
+ΔPmj) Poj)... (3) Here, G and i are the gains, Mj is the mill constant of the J-th stand, and P o j is the predicted rolling load before rolling of the J-th stand. In a 7-stand continuous hot rolling mill, a thickness gauge and a thermometer were installed on the exit side of the 5th stand, and the target final exit side plate thickness was 2°3.
■For a bottom strip with a width of 1200 s+m, the present invention method, a comparative method in which υje was performed only based on the plate thickness deviation detected by a thickness gauge, and an uncontrolled conventional method were carried out. Table 1 below shows the tip plate W precision V (maximum g difference in final exit side plate thickness deviation) at the time. As is clear from Table 1, according to the method of the present invention, a good plate thickness could be obtained from the tip of the hot strip, which is an unsteady rolling region.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing a control procedure of an embodiment of the method for controlling tip plate thickness of a continuous hot rolling mill according to the present invention, and FIG. 2 shows the configuration of a continuous hot rolling mill to which the present invention is applied. It is a block diagram. 16... Roll down position detection device, ΔS1... Roll down position deviation, 20... Thickness meter,
Δt1mi---Standard rolling section exit side plate thickness deviation, 22...
・Thermometer, ΔTsmi...Surface temperature fii difference of steady rolling section, 30
...training machine, S, ...down position, ΔSt
j... Amount of correction of the downward position of the tip, ΔS m j...
Amount of rolling position correction in the steady rolling section.

Claims (1)

[Claims] (1) In a hot continuous rolling mill, a thickness gauge and a thermometer are installed on the exit side of at least one stand other than the last stand, and the rolled material is rolled at the i-th stand immediately before the installation location of the thickness gauge and thermometer. Immediately after being bitten by the machine, the rolling load at the tip of the material to be rolled is detected, and then the exit plate thickness, surface temperature, and rolling load at the steady rolling part of the material to be rolled are detected, and the rolling load at the i-th stand is detected. The ratio of the rolling load at the tip of the rolled material to the rolling load at the steady rolling section is calculated, and based on the calculated value as well as the plate thickness and surface temperature of the steady rolling section, the A method for controlling plate thickness at the tip of a continuous hot rolling mill, characterized by correcting the rolling position of a stand.