JPS6049810A - Control method of sheet thickness during running in continuous mill - Google Patents

Abstract

PURPOSE:To correct a draft rapidly and surely by detecting the deviations with respect to the reference values of a rolling load and a draft position respectively to estimate the deviations of the temperature of a rolling material and its sheet thickness at the inlet side at the next stand and correcting the draft position in accordance with the results calculated basing on the estimated values. CONSTITUTION:The deviation DELTAPi of a rolling load and the deviation DELTASi of a draft position from respective set reference values are detected respectively by a load cell 2 and a draft position control device 3 at the time of biting the front tip 1a of a material 1 to be rolled by the (i)th stand to estimate the temperature deviation of the material 1 and the sheet thickness deviation at the inlet side at the next (i+1)th stand by performing prescribed calculations by an arithmetic device 4, and the correcting quantity DELTASi+1 of draft position at the (i+1)th stand is calculated basing on the estimated value. Next, the correction of said draft position is performed basing on said calculated value before biting the front tip 1a by the (i+1)th stand. In this way, the draft is corrected rapidly and surely, and the accurate sheet thickness is obtained from the front tip of a coil.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling sheet thickness during sheet passing in a continuous rolling mill.

In order to obtain a good sheet thickness from the tip of the 5th mill when passing the sheet through a hot continuous finishing mill, etc., set the rolling position of each stand to the appropriate position (setup) There is a must drink.

In the past, the rolling position of each stand was set by analogy with past rolling data, operator experience, etc., but recently rolling theory formulas (rolling load formula, deformation resistance formula, vJ
It is increasingly being carried out by Ku↑Atun machine, making full use of fP4 temperature formula, etc. Even if you set the reduction position of each stand using theoretical calculations, it is difficult to say that they are actually at the maximum of 311i1.
Good plate thickness could not always be obtained from the tip of the coil. However, there is a problem with the accuracy of the theoretical formula used for the set-up calculation (and the input condition of the finish rolling mill, which is detected by a release thirst meter, etc.), which is necessary as an input condition for calculation. This is because there is a detection error in the temperature of the rolled material or the plate thickness calculated by the gauge meter formula, etc.The former theoretical formula can be improved by collecting actual rolling data, but the latter. At present, it is difficult to measure the temperature or plate thickness of the rolled material with high precision.In particular, when measuring temperature, the measured value may vary due to problems such as the surface properties of the rolled material or water riding. Not only are there many good differences between the actual values and the actual values, but what is required for set-up calculations is the average temperature in the plate thickness direction, which is no better than estimating it from the actually measured surface temperature.

From the above points, in order to obtain a good plate thickness from the tip of the plate, it is necessary to correct the rolling position of each stand to an appropriate value during sheet threading. As a countermeasure for this, a gauge meter AGC [Au[omatlq G
It is conceivable to use a1n Control J from the time of sheet threading, but since it is feedback control, the response of the rolling down device becomes a problem, and it is difficult to obtain a good sheet thickness from the tip of the sheet.

In addition, as another means, detect the rolling width difference of the front stage stand, calculate the deformation resistance deviation from this, and assume that the deformation resistance deviation is the same in the rear stage stand,
A method has been proposed (Japanese Patent Publication No. 51-2061) for quickly correcting the lowered position of the rear stand. However, the deformation resistance is a complex function of material temperature, rolling reduction, and chemical composition, and it is difficult to predict the deformation resistance of the rear stand from the deformation resistance of the front stand.

The present invention was made in view of these conventional problems, and is a one-pull continuous rolling mill that has quick response, reliable calculation results, and can reliably correct the rolling reduction. The purpose of this paper is to provide a method for controlling sheet thickness during sheet threading, and to obtain accurate sheet thickness from the tip of the coil.

In the present invention, when the tip of the material to be rolled is bitten into the i-th stand from upstream when the material is passed through a continuous rolling mill, the reference value of the rolling load of the i-th stand and the rolling position of the material are determined. Detect the respective deviation amounts from the base ￥=feed, use these deviation amounts to predict the rolled material rotation deviation and entry side plate thickness deviation at the next stand, 1+1, and use these predicted values to calculate the 1+1. The above objective is achieved by displaying the correction value of the rolling position of the 1st stand and correcting the rolling position of the i+1th stand before the tip of the material to be rolled is bitten by the 1+1Nth stand. It is.

The present invention focuses on the fact that, for example, in hot rapid continuous finish rolling (hot streak mill finish rolling), the main cause of sheet thickness variation is temperature variation, and that temperature variation can be recognized as load variation. I came up with the composition.

The present invention will be described in detail below using the drawings.

As shown in FIG. 1, the method of the present invention applies
When a is caught in the i-th stand from the upstream (hereinafter simply referred to as i-stand), the rolling load deviation ΔP+ and the rolling position width difference ΔS+ from the set reference value are determined by the load cell 2 and the rolling position controller, respectively. @3, and from these rolling load deviation ΔP+ and rolling position @difference ΔSi, the computer 4 performs a predetermined calculation to determine the next stand 1+1.
The temperature deviation of the material to be rolled and the deviation of the plate thickness at the entrance side of the stand are predicted, and the rolling position correction amount ΔS country - of the 1+1st stand is calculated based on the predicted values, and the tip 1a of the material to be rolled 1 is bitten by the next stand. This is to correct the lowering position of the i+1 stand before it is lowered. In the figure, 5 is a looper for measuring tension.

Said rolling? i! i fold deviation 8P+ and reduction position width difference ΔS
A method of calculating the rolled down position correction value ΔS I41- from 1 is described below.

Rolling load P1 when the tip 1a is caught in one stand
is different from the predicted value and the same deviation ΔPi occurs because, assuming the rolling theoretical formula is correct, the entrance plate thickness H1, the temperature of the rolled material 11, the rear tension tb+, and the rolling position 81 at that time are,
This is the I value used in the setup calculation and varying from t:m. Therefore, the rolling load deviation ΔP1 at that time is expressed by the following equation.

ΔP r = (aP/aH)+・ΔH1+(aP/SaTri・ΔT1 + (aP/?3Lb) I・Δt1)1+(aP/a
s) 1・ΔS1...(1) Here, Δl-1+, Δ
Tl, Δ[old, ΔS1 is the deviation from the respective reference 1id (setup value), subscript ihas'; tnt7fj14
, (aP/aH), (aP/81-), (clP, /'
c. This influence coefficient can be determined by a theoretical formula or process experiment.

Solving equation (1) for the temperature deviation of the rolled material Δ゛' lips leads to the following equation.

Therefore, the rolling material temperature deviation T1 is the rolling load deviation ΔP
+, inlet root lli difference △1-1i, Δ posterior tension deviation Δ(
b; If the rolling position deviation ΔS1 can be detected, the equation (2) can be used. Here, rolling TfJ weight deviation ΔP+, rolling position deviation Δ
S+ can be detected directly. Further, the inlet side plate thickness deviation ΔH1 is equal to the outlet side plate thickness deviation (gauge meter plate thickness deviation) Δl+1-1 of the upstream stand (stand 1-1), and is expressed by the following equation.

Δ Hi= Δ h+−+= Δ 'S t−+ +
Δ P t-+ /' M r-+ (3) Here, fvl i=1 is the Mill constant at i-1 stand.

By the way, it is very difficult to detect and cover the rear tension deviation △
i is attached to the shaft of the looper 5 (it can be detected from the tension meter or the torque generated by the looper), but immediately after the coil tip 1a passes the 1st stand, the looper 5 of the 1-1 stand is rising and is not in contact with the strip. This is because there is no difference in the rear tension B, or even if they are in contact, it is in a very unstable state.However, it is thought that the influence of the rear tension difference B Δtb+ on the load is small, so in reality, this rear tension deviation Δtb+ has a small effect on the load.
The temperature deviation ΔT1 of the rolled material may be calculated by ignoring tbi. Therefore, equation (2) becomes equation (4).

On the other hand, when the tip is bitten by the ++1 stand, the entry side plate thickness deviation ΔH country, the temperature deviation of the rolled material △1° country is the rolling WJ load difference ΔP+, the rolling side pressure deviation ΔS+, and the temperature deviation of the rolled material Δ
It is calculated by the following formula using T +.

ΔH+++ ”'Δ111=ΔS1+ΔP+/M+...
・(5) ΔT+”F−ri・ΔT1 ・・・(6) Here, F
T+ is a constant determined by the rolling schedule.

Yotsu τ, said entrance side plate thickness deviation ΔH+++, temperature of rolled material 1&
The exit plate thickness deviation Δli DI− at the i+1 stand, which is expected to occur due to 4ΔT +++, is calculated by the following formula.

In addition, the correction amount ΔS+, 1− of the reduction position in order to make the exit side plate thickness II +++ of the 1+1 stand as the target (Δh +++ = O) is the exit side plate thickness deviation ΔII + in equation (7).
It is calculated using the following formula using 41-.

To summarize the above steps, when the tip 1a of the material to be rolled 1 is bitten by the i-stand, (Δ) rolling load deviation ΔP
+, pressure lower I! Determine the deviation ΔS1 directly, and set the inlet side plate thickness deviation ΔH1 at the upstream + -1 stand as the outlet side plate thickness deviation Δ11 to 1 using equation (3); (B) The obtained ΔP+, ΔS1, Using Δl-4+, 1 in equation (2), specifically, equation (4) ignoring the rear tension deviation Δtbi.
Calculate the difference Δ1-1 between the temperature of the rolled material and the temperature at the stand: (C)
Using the obtained ΔT1, the temperature deviation of the rolled material Δ1−country is determined by the formula (6), and the entrance plate thickness deviation ΔH,+, at the t+1 stand is determined by the formula (5): ( D) Konmeteta Δ
Using T +++ and ΔHill, the exit side plate thickness deviation Δ111 and l− at the ++1 stand that are expected to occur are (
7) From the formula: (E) Using the obtained Δ1+ I◆1-, the exit side plate thickness h at the i+1 stand is set as the target (
Amount of correction Δ of the reduction position to achieve Δb kl ” O)
St and l' are determined by equation (8):

Based on the determined correction amount ΔS i+t' of the rolling position, the rolling position of the 1+1 stand is corrected before the tip 1a of the material to be rolled 1 is bitten by the t+1 stand.

As a result, each time the material to be rolled passes through each stand, the rolling position is corrected based on the detected value at the upstream stand so that the thickness is the specified thickness, and the material to be rolled is The board will be finished to a predetermined thickness.

Table 1 shows the
1. The results of comparing the plate thickness accuracy (standard deviation of the final exit side plate thickness deviation) at the tip of the coil when the present invention is implemented with that of the conventional method (no control) are shown. As is clear from the table, it can be confirmed that the thickness defects at the tip have been significantly improved.

As explained above, according to the present invention, it is possible to reliably secure a predetermined thickness from the tip of the material to be rolled, and it is possible to perform rolling with a good yield.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing an embodiment of a continuous rolling mill in which the method for controlling plate thickness during sheet passing in a continuous rolling mill according to the present invention is adopted. ΔP1...Rolling load l! ii difference, ΔSt...rolling position deviation, ΔS kl-...rolling correction value, ΔT'+...rolled material humidity deviation, ΔH1...inlet side plate thickness deviation. Agent Shima Yaron (one idiot Figure 1)

Claims (1)

[Claims] (1) When the material to be rolled is passed through a continuous rolling mill, when the tip of the material to be rolled is bitten by the first stand from upstream, the reference value of the rolling load of the first stand and the reference value of the rolling position are determined. The amount of deviation from each value is detected, and based on these deviation amounts, the 1 degree deviation in ai of the rolled material and the deviation in the entrance plate thickness at the i+1st stand, which is the next stand, are predicted. A continuous rolling mill characterized in that the correction amount of the rolling position of the i+1th stand is corrected at l1fl when the tip of the rolled flat Δ is bitten by the i,100th stand. A method for controlling plate thickness during sheet threading.