JPH0413413A - Method for controlling strip thickness at passing time on hot continuous rolling mill - Google Patents

Abstract

PURPOSE:To allow the stable strip thickness control by using together the deviation of surface temperature with the temperature measured value between the stands and the temperature deviation recognized with the deviation of rolling load and the deviation of rolling reduction position, and searching for the temperature deviation of the material to be rolled. CONSTITUTION:At least, two sets of the thickness meter 9A, 9B and, at least, one set of the temperature meter 17 are set between the stands, the rolling load of the prescribed stand and the sheet thickness of the material to be rolled 1 is detected at the time when the tip end 8A of the material to be rolled passes through the stand. The temporary rolling temperature deviation of the following stand is predicted with the rolling load and the sheet thickness. And the surface temperature of the material to be rolled is detected at the time the tip end 8A passes through the temperature meter 17, the rolling temperature deviation of the material to be rolled 1 is predicted at the following stand into which the tip end 8A of the material to be rolled is not yet bitten with the temporary rolling temperature deviation and the surface temperature of the material to be rolled. The position of rolling reduction of the following stand is corrected with this predicted value of the rolling temperature deviation and the detected value of sheet thickness deviation. Therefore, the sheet thickness satisfying the target from the tip end of hot strip can be obtained.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an improvement in a method for controlling the thickness of a rolled material during passing in a hot continuous rolling mill, which controls the thickness of a rolled material when the material is passed through a hot continuous rolling mill having a plurality of stands. .

[Conventional technology]

In order to obtain the desired thickness from the tip of the hot strip during strip passing in a hot continuous rolling mill, for example a hot continuous finishing mill, it is necessary to set the roll gap (placed between the rolls of each stand) at an appropriate position in advance. It is necessary to set it up. Traditionally, the rolling position setting of each stand was done by analogy with past rolling data, operator experience, etc., but recently rolling theory formulas (rolling load formula, deformation resistance formula, gauge meter formula, rolled Increasingly, this is carried out using a total of X machines, making full use of the material temperature formula, etc. To set the rolling reduction of each stand using this calculator, input the surface temperature data of the material to be rolled at the entrance of the rolling mill detected by a radiation thermometer etc. into the calculator, and use this data based on a theoretical formula preset in the calculator. The process is carried out to calculate the set value of the roll reduction, and the position of each stand is set based on this set value of the roll reduction. However, even if the reduction settings for each stand were determined by theoretical calculations, it was difficult to say that they were actually the optimum values, and a good plate thickness could not always be obtained from the tip of the coil. This is because there is an accuracy problem with the theoretical formula used for the setup calculation, and also because the surface temperature of the rolled material at the entrance of the finishing rolling mill, which is detected by a radiation thermometer etc., is required as an input condition for the calculation. This is because there is a detection error in . Of these, for the former theoretical formula,
Although it may be possible to improve this by accumulating rolling performance data, it is currently difficult to measure the surface temperature of the rolled material on the entry side of the finishing rolling machine with high precision. In other words, when measuring surface temperature, not only are the measured values and actual values often discrepant due to the surface properties of the rolled material or problems in the measurement environment such as riding on water, but the set-up calculations require This is the average temperature in the thickness direction, and there is no other way to estimate it than from the actually measured surface temperature, and there is a possibility that errors may occur depending on the plate thickness size, etc. From the above points, in order to obtain a good plate thickness from the tip of the hot strip, it is necessary to correct the rolling position of each stand to an appropriate value during sheet threading. As a countermeasure for this, gauge meter AGC (Automat+cG auge C
It is conceivable to adopt it from the time of sheet threading, but since it is a feedback control, the responsiveness of the control will be a problem, and the actual roll opening required by the gauge meter type, the thermal expansion and wear of the rolls due to rolling. It is difficult to obtain a good thickness from the tip of the coil due to the fact that the exact thickness cannot be calculated due to changes in the thickness of the coil. Furthermore, as a method of corrective control, JP-A-59-144510 proposes a method of installing a thickness gauge between the stands and correcting and controlling the rolling cover or rolling load based on the detected thickness deviation of the material to be rolled. are doing. However, although the temperature deviation of the rolled material has a large effect on the load fluctuation during rolling, no method has been considered to accurately predict it, and as mentioned above, there are various problems when measuring the temperature of the rolled material. Since this is done by measuring the surface temperature using a radiation thermometer or the like, it is difficult to obtain a good plate thickness. In addition, as another method, the deformation resistance deviation is calculated by detecting only the rolling load of the front stage stand, or both the plate thickness by the stand open thickness gauge and the rolling load on the upstream side of the thickness gauge, and calculating the deformation resistance deviation. is the same for the rear stand, or the rate of change of deformation resistance deviation is the same for each stand, and a method of correcting the lowering position of the rear stand within a short time based on these values (Japanese Patent Publication No. 51-2061,
JP-A-63-220915) has been proposed. However, the deformation resistance is a complex function of the temperature of the rolled material, rolling reduction, rolling speed, chemical composition, etc., and it is difficult to predict the deformation resistance of the rear stand from the deformation resistance detected at the front stand. On the other hand, the inventors have already proposed in Japanese Patent Application Laid-Open No. 60-247408 as a way to solve the above-mentioned problems. A method is disclosed in which the deviation is predicted and the reduction is corrected before the material to be rolled is bitten. According to this method, if the rolling position detected from the rotation of the rolling screw and the movement of the hydraulic cylinder matches the actual roll opening (gap between the upper and lower work rolls), the target plate thickness can be achieved from the tip of the coil. It has the advantage of being able to obtain

[Problems to be achieved by the invention] However, in the method of determining the temperature of the rolled material from the surface temperature of the rolled material predicted by a thermometer placed between the stands, as described above, the measurement environment, plate thickness size, calculation formula error There is a possibility that errors may occur due to such factors. In addition, in the method of JP-A-60-247408, the temperature of the rolled material, which has a large effect on load fluctuations during rolling, is calculated from the measured values of the rolling position deviation and rolling load deviation of the rolling rolls. The formula contains errors. Further, as the number of rolling rolls increases, thermal expansion and wear of the rolls occur and the detected rolling position no longer matches the roll opening degree, making it impossible to detect correct rolling position deviation and rolling load deviation. For these reasons, calculation of the temperature of the rolled material using this method becomes inaccurate. Therefore, in the past, it was not possible to accurately obtain the temperature of the material to be rolled, so there was a problem that the control of the plate thickness became unstable. The present invention was made to solve the above-mentioned conventional problems, and it is possible to measure the temperature deviation of a rolled material, which has a large influence on load fluctuations, by measuring the influence of the measurement environment, plate thickness size, thermal expansion and wear of the rolling rolls, etc. A method for controlling plate thickness during threading in a hot continuous rolling mill, which allows accurate and stable reduction correction to be performed without causing any damage, and reliably obtains the target plate thickness from the tip of the hot strip. The purpose is to provide

[Means to achieve the task]

The present invention provides a method for controlling the thickness of a rolled material during passing through a hot continuous rolling mill having a plurality of stands, in which the thickness of the rolled material is controlled when the material is passed through a hot continuous rolling mill having a plurality of stands. At least two thickness gauges and at least one thermometer are installed between them, and when the tip of the rolled material passes through a predetermined stand, the rolling load of the stand and the thickness of the rolled material are detected. , predict the pre-rolling temperature deviation of the trailing stand based on the rolling load and plate thickness, detect the surface temperature of the rolled material when the tip passes the thermometer, and calculate the pre-rolling temperature deviation and the surface of the rolled material. The rolling temperature deviation of the rolled material at the trailing stand where the tip of the rolled material has not yet been bitten is predicted from the temperature, and the rolling position of the trailing stand is corrected based on the predicted rolling temperature deviation value and the detected plate thickness deviation value. By doing so, the above-mentioned problem has been achieved.

[Effect]

The present invention was made by focusing on the fact that the main causes of plate thickness variation in hot continuous rolling are temperature deviation and entrance side plate thickness deviation. and - at least two thickness gauges are installed between the stands to detect plate thickness deviations, and at least one thermometer is installed between the stands to check the temperature deviations more accurately, and the temperature measurement The temperature deviation of the rolled material is determined by using the surface temperature deviation based on the value and the temperature deviation recognized from the rolling load deviation and rolling position deviation. In this way, by determining the correct temperature deviation of the rolled material, stable plate thickness control can be performed.

【Example】

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 shows a hot continuous rolling mill to which this embodiment is applied, and the number of stages of rolling stands is 1f. The rolled material 8 is fed out from the left side in FIG.
The tip 8A of the material to be rolled is located slightly to the right of the thickness gauge 9. Each rolling stand is composed of a work roll 10 and a backup roll 12, and a rolling load deviation ΔP in the rolling stand is detected by a load cell 14, and a rolling position deviation ΔS is detected by a rolling position control device 16. 16 corrects the rolling position of the rolling stand to the position commanded by the rolling position correction amount ΔS' inputted from the computer 22. The calculator 22 contains the rolling load deviation ΔP detected by the load cell 14, the rolling position deviation ΔS detected by the rolling position control device 16, and the respective plate thicknesses Δ detected by the thickness gauges 9A and 9B.
h i-I, Δhi and the temperature calculation ΔT of the rolled material detected by the thermometer 17] is input into the calculator 22, and the calculator 22 calculates the temperature as shown in the flowchart of FIG. 1 based on this input data. Such processing is performed internally, and based on the processing results, the rolling position correction amount ΔS°° is output to each rolling stand. The processing carried out inside the machine 22 is as shown in the flowchart of FIG. The effects of the embodiment will be explained below. In Fig. 2, the tip #A8A of the rolled material 8 fed from the left is the 1-1 stand, the 1st stand, and the thickness gauge 9.
At the time of passing through these rolling stands, the rolling load deviation ΔP i-1 and ΔP rolling position difference ΔS i- are determined by the load cell 14 and rolling position control device 16 arranged in each rolling stand. 1, ΔS1
is detected. Also, during this time, at each point in time when the tip end 8A of the rolled material passes through each position where the thickness gauges 9A, 9B and the thermometer 17 are arranged, the thickness deviation measurement values Δhi-1 and Δ are obtained, respectively.
hi, the surface temperature deviation ΔT1 of the rolled material is detected. These detection and measurement processes correspond to steps 40, 42, and 44 in the flowchart of FIG. The rolling load deviation ΔPi and the predicted thickness deviation value Δhi-1,
From ΔEli, by the following formula, the rolled material 8 at the time when the tip 8A of the rolled material is bitten by the roll 10 of the first stand
Calculate the preliminary rolling temperature difference ΔT'I. ΔT'i=(ΔP (a P/aH) i xAh 1-((21P/ah); xΔtli)/
(aP/c)T)i - (1) Kokote, (aP/aH)i, (c)P/ah)i, (c)P/
aT)i is an influence coefficient of the inlet side plate thickness H1, the outlet side plate thickness h1, and the rolling temperature Tj on the rolling load P of the first stand. Subsequently, due to the plate rolling temperature deviation ΔT'1 of the material to be rolled 8 in this first stand, the tip end 8A of the material to be rolled is 1+1.
The plate rolling temperature deviation ΔT ′i+1 of the material to be rolled 8 at the time when it is bitten by the stand is determined by the following formula. ΔT′i+l= (c)T;, +/aTi )XΔT
′・・・・・・・・・ (2) Here, < a T ;++ / c) T i ) is the first effect on the 1st + 1st stand rolling temperature deviation T ill
This is an influence coefficient of the stand rolling temperature deviation T1. Further, when the tip 8A of the rolled material passes the thermometer 17 placed between the first stand and the +1st stand, the surface temperature deviation Δ of the rolled material detected by the thermometer 17 is detected.
From T i and ill, the plate rolling temperature deviation ΔTI+ and 1 of the material to be rolled at the i+1st stand is determined by the following formula. ΔT ” ill −(cl T ill / b T
i, ill)×ΔT j, ill...
・・・・・・・・・(3) Here, (a T r-+ /
a T i , i-+ ) C. This is the influence coefficient of the surface temperature of the rolled material between the 1st and 1+1st stands on the rolling temperature of the rolled material of the i+1st stand. Subsequently, in this embodiment, in determining the rolling temperature deviation ΔT, 1 of the rolled material used to calculate the rolling position correction value, the plate rolling temperature deviation ΔT'i, 1 (first stand) of the rolled material is calculated. Calculated from the rolling load deviation ΔPi, etc.)
and the plate rolling temperature deviation ΔT'' ill of the material to be rolled (calculated from the surface temperature measurement of the material to be rolled by the thermometer 17). As mentioned above, this is calculated from the rolling load of the rolling stand. There are errors in calculation formulas, etc. in the temperature deviation of the rolled material, and
As mentioned above, there are detection errors in the measured value of the surface temperature of the rolled material detected by a radiation thermometer or the like, so this is to cancel out these errors. This rolled material rolling temperature deviation Δ
T in can be determined by the following equation, where α is a predetermined coefficient that depends on the measurement environment, plate thickness, etc. (the worse the measurement environment or the thicker the plate, the larger this α becomes). Δ T, meeting 1: α i◆1 × Δ T ′ i
◆10(1-αi+I)×ΔT゛1, 10≦αi, 1≦1 (4) From the rolling temperature deviation ΔT ill of the rolled material at the 1st + 1st stand, further, The rolling temperature deviation ΔT i-2 of the material to be rolled at the 1st + 2nd stand is determined by the following formula. ΔT, +2= <;aT;, z/a Ti +)
XΔTi and Bi... (5) Here, (a Ti-2/
C) T ill ) C is the influence coefficient of the rolling temperature of the rolled material of the i+1st stand on the rolling temperature of the rolled material of the 1st + 2nd stud. In this way, it is possible to predict and calculate the rolling temperature deviations ΔT ill and ΔT1 Y2 of each rolled material when the rolled material light #A8A is bitten by the 1st + 1st stand and the 1st + 2nd stand. The process of performing the prediction calculation corresponds to the step 48 of calculating each stand temperature deviation in the flowchart of FIG. Subsequently, the calculator 22 converts the measured thickness deviation value Δhi and the rolling temperature deviation of the rolled material 8 into T=, wealth, ΔTill, and the following 2.
The respective reduction position correction amounts ΔS' in the 1st+1st stand and the 1st+2nd stand are determined by two formulas. Find i and 1, ΔS'°1 and 2. ΔS ” ill = (G ill / M ill
)X ((a P / a H) ill X A h
;”, (a P / ;3 T) ill X
ΔT r++ 1ΔS ++, or 2 = (G
i and 2/M; and 2) x (a P/c)
T ) r-2XΔT ill where G is the gain constant and M is the Mill stiffness constant. In this way, the calculator 22 can
Respective reduction position correction amount Δ3 + in 2 stands
+ , +, , Δ3 ++ , 2 can be calculated, and this calculation process corresponds to step 50 of calculating the correction amount of each stand lowering position in the flowchart of FIG. Finally, the calculator 22 calculates the 1st + 1st stand and the 1st + 2nd stand.
In order to control the plate thickness by correcting the rolling positions of the stands, the respective pressure plate position correction amounts ΔSI+, +, ΔS IIi+2 in these stands are controlled by rolling position control devices 16 disposed in the respective stands.
Output to. Then, the rolling position control device 16 disposed in these stands corrects the rolling position of the rolling rolls based on this rolling position correction amount ΔS ++ before the rolled material light @8A is bitten. , control is performed to obtain the correct plate thickness. In this embodiment, as described above, at least one thickness gauge and at least one thermometer are arranged, and in this way, the
By correcting the rolling position of the 1+1 stand and the 1+2 stand, it is possible to obtain the target thickness from the tip of the hot strip. It is possible to measure the temperature deviation of the material, and as the number of rolls increases, thermal expansion and wear of the rolls occur, and even when the detected rolling position does not match the roll opening degree, correct thickness control can be performed. In addition, in Table 1 below, in a 7-stand continuous hot rolling mill, a thickness gauge and a thermometer are placed between the 5th stand and the 6th stand, and the target final exit plate thickness is 2.311 and 5.0 mm.
For a hot strip of (width i 200+sn),
The tip plate thickness accuracy (standard deviation of final exit side plate thickness deviation) when implementing the method of the present invention, a comparative method in which control is performed only based on the plate thickness deviation detected by a thickness gauge, and a conventional method without control, respectively. show. However, the value of α in equation (4) of the present invention method is based on the target plate thickness of 2.3i.
The I thickness was set at 0°4, and the target plate thickness was set at 5.0iI thickness at 0.6. Table 1 As is clear from Table 1, according to the method of the present invention, excellent results were obtained in that a good plate thickness could be obtained from the tip of the photo strip. In addition, in the above embodiment, the thickness gauges 9A and 9B were arranged between the 1-1st stand and the 1st stand, and between the 1st stand and the 1st+1st stand, respectively, to detect the plate thickness deviations Δh1-1 and Δhi. These Δh i-1 and Δhi are i-th
It is also possible to detect the rolled-down position S i-I of the first stand and the rolled-down position S1 of the 1st stand and obtain it using a gauge meter method. Of course, a thickness gauge is not required at this time.

【Effect of the invention】

As explained above, according to the present invention, it is possible to accurately measure the temperature deviation of a rolled material while suppressing the influence of the measurement environment, plate thickness size, calculation formula error, thermal expansion and wear of the rolling rolls, and the like. Therefore, it is possible to reliably and stably correct the reduction of the rolling rolls, and it is possible to obtain the excellent effect that the target thickness can be obtained from the tip of the hot strip during sheet passing.

[Brief explanation of drawings]

FIG. 1 is a flow diagram showing a control flow of an embodiment of the method for controlling plate thickness during rolling in a hot continuous rolling mill according to the present invention, and FIG. FIG. 2 is a block diagram showing the configuration of a method for controlling plate thickness of an intermittent continuous rolling mill. 22... Calculator - ΔP... Rolling load difference, ΔS...
・Driving position deviation, ΔS°゛・・・Driving position correction amount, Δ
T1...Measured value of surface temperature deviation of rolled material, Δh i-1
, Δhi... Thickness deviation measurement value.

Claims (1)

[Claims] (1) In a sheet thickness control method during sheet passing in a continuous hot rolling mill, which controls the thickness of the rolled material when passing the sheet through a hot continuous rolling mill having multiple stands, At least two thickness gauges and at least one thermometer are installed in the machine, and when the tip of the rolled material passes through a predetermined stand, the rolling load of the stand and the thickness of the rolled material are detected, Predict the preliminary rolling temperature deviation of the following stand based on the rolling load and plate thickness, detect the surface temperature of the rolled material at the time when the tip passes the thermometer, and calculate the preliminary rolling temperature deviation and the surface temperature of the rolled material. From this, predict the rolling temperature deviation of the material to be rolled at the trailing stand where the tip of the material to be rolled has not yet been bitten, and correct the rolling position of the trailing stand based on the predicted rolling temperature deviation value and the detected plate thickness deviation value. A method for controlling plate thickness during threading in a continuous hot rolling mill, characterized by: