JPS6255444B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plate thickness control device for a rolling mill, and is particularly intended to eliminate plate thickness deviation at the exit side of the rolling mill.

In a rolling mill, the rolling position and number of roll rotations are predicted and calculated in advance before the material to be rolled is bitten by the rolling mill, so that the exit side plate thickness is the target plate thickness. ), and set the rolling position and roll rotation speed to the calculated values in advance (this setting is called a preset).
It is done like this.

However, in reality, if there is a prediction error in predicting the deformation resistance of the material to be rolled, or if there is an error in determining the thickness of the material to be rolled at the entrance of the rolling mill, the calculation results in the schedule calculation may be affected. A prediction calculation error will be introduced, and as a result, the strip thickness at the exit of the rolling mill will often not be the target strip thickness.

Therefore, the present invention aims to eliminate the deviation in the thickness of the sheet at the exit side of the rolling mill due to such schedule calculation errors.

An example of the present invention will be described in detail below with reference to the drawings.
First, considering the schedule calculation for Figure 1, H _p is the predicted thickness at the entrance of the rolling mill, H _A is the true thickness at the entrance of the rolling mill, h _A is the true thickness at the exit of the rolling mill, h _p is the target plate thickness on the exit side of the rolling mill, S _p is the set value of the rolling position obtained by schedule calculation, S' is the rolling position after correction taking into account the prediction error of the plate thickness on the entry side and the prediction error of deformation resistance, F _p is the predicted rolling force when the entrance plate thickness is H _p and the rolling position is S _p , and F _A is the predicted rolling force when the entrance plate thickness is H _A and the rolling position is S _p . .

In FIG. 1, the deformation resistance equivalently corresponds to the slope of the F _p -H _p line (this is called the A line) or the F _A -H _A line (this is called the B line). Therefore, while the predicted value for the entry side plate thickness is H _p , the true value is H _A , and there is an error corresponding to that value. Regarding deformation resistance, if the predicted straight line A and the actual straight line B do not match, the plate thickness at the exit side of the rolling mill will be h _A and an error will occur between it and the target plate thickness h _p . .

From the above considerations, it can be seen that if there is an error in the prediction of the entry side plate thickness and the prediction of the deformation resistance, in order to obtain the target plate thickness h _p , it is sufficient to correct the rolling position from S _p to S'. .

The present invention is based on this principle, and in FIG. 2, the rolled material 4 is the roll 1a of the i-th stand ST _i .
, the thickness h Ai of the exit side of the i-th stand is determined using the pressure position S _Ai detected by the rolling position detection control device 2a and the rolling force F _Ai detected by the rolling force detection device _3a . If we calculate h _Ai = S _Ai + F _Ai / M _i + OFS _i (1). Here, M _i is a Mill constant, and OFS _i is a correction term including oil film thickness correction.

On the other hand, in the schedule calculation, the predicted rolling value F _p is obtained based on the following formula.

F _pi =K _pi・W _pi・√′ _pi ( _pi − _pi )・Q _i …(2) Q _i =f ₁ (R′ _pi , H _pi , h _pi )…(3) R′ _pi = f ₂ (R _i , F _pi , H _pi , h _pi ) ...(4) Here, R _i is the roll radius of the i-th stand, K _pi
is the predicted average deformation resistance of the i-th stand, W _pi is the i-th stand
The predicted plate width of the stand, R′ _pi is the predicted flat roll radius of the i-th stand, f ₁ (R′ _pi , H _pi , h _pi ) and f ₂
(R _i , F _pi , H _pi , h _pi ) is a function.

Therefore, the rolling down position S _pi for obtaining the target exit side plate thickness h _pi can be determined from the gauge meter equation (1) as S _pi =h _pi −F _pi /M _i −OFS _i (5).

In the above equations, the mill constant M _i and offset OFS _i do not vary depending on the factors of the material to be rolled, but are related to factors of the mill mechanical system, so the prediction accuracy can be considerably improved. .

On the other hand, since the roll radius R _i and the strip width W _pi are known in advance, in order to accurately obtain the predicted rolling position S _pi for rolling to the target strip thickness h _pi , the rolling force F
It is necessary to accurately predict _pi , in other words, it is necessary to accurately grasp the average deformation resistance K _pi and the entry side plate thickness H _pi based on equation (2).

Therefore, in Fig. 2, the measured value h _Ai of the plate thickness on the exit side of the i-th stand can be obtained from the gauge meter formula of equation (1), and the measured value h Ai of the plate thickness on the inlet side of the i-th stand
_Ai is the actual measured value of the plate thickness at the exit side of the (i-1)th stand before the i-th stand. Considering that _A(i-1) is the actual measured value of the plate thickness at the inlet side of the i-th stand, H _Ai = h _{A (i-1)} =S _A(i-1) +F _A(i-1) /M _(i-1) +OFS _(i-
1) …(6) can be obtained.

Therefore, the average deformation resistance K _pi used in the prediction calculation,
The following relationship holds true between the average deformation resistance K _Ai obtained from the measured value during rolling.

The value TREND _i obtained by this formula is called the average deformation resistance correction coefficient, and since the right side is a function of the measured value and the value known in advance, it can be easily calculated.

Note that the average deformation resistance correction coefficient obtained using equation (7)
TREND _i is the calculation result for the i-th stand alone, but the same calculation is performed for the stands upstream from the i-th stand, and the amount of reduction position correction after the (i+1)th stand is calculated using the following formula. Accordingly, the average deformation resistance correction coefficient _i may be weighted and used. In this way, a more stable correction function can be maintained. Note that in equation (8), α _ij is a weighting coefficient.

However, the prediction error of the average deformation resistance, which is a factor of plastic deformation of the rolling mill at the i-th stand, is
1) It is thought that a similar prediction error occurs when the stand is bitten, and the prediction error for the exit side plate thickness of the i-th stand is the (i+1)-th
This is an error in predicting the plate thickness at the entrance to the stand. Therefore, when the material to be rolled is bitten by the i-th stand, the exit plate thickness error for the (i+1)th stand can be predicted. (i+1)th
At the same time as the operation of correcting the lowered position of the stand begins, for the (i+2)th and subsequent stands, the (i+2)th
1) Based on correcting the thickness of the outlet side of the stand to match the target thickness, it can be assumed that there is no error in the thickness of the inlet side, and in the end, it is only necessary to perform the reduction correction operation for the prediction error of the average deformation resistance. It turns out.

In other words, the (i+
1) The predicted rolling force F _p(i+1) of the stand is However, R′ _{p(i+1) is} the flat roll diameter obtained from F′ _p(i+1) and H _A(i+1) , R _p(i+1) is F _p(i+1) , The flat roll diameter obtained from H _p(i+1) , Q′ _p(i+1) is R′ _p(i+1) , the rolling force function obtained from H _A(i+1) , Q _{p(i +1)} is the rolling force function determined from R _{p (i+1)} and H _{p (i +1)} .

As shown, the average deformation resistance correction coefficient TREND _i obtained when the i-th stand is engaged and the actual measurement value of the entrance plate thickness H _{A (
i+1)} H _A(i+1) = h _Ai ...(10), and correct the lowering position of the (i+1)th stand as S′ _p(i+1) = h _p(i+1) − F′ _p(i+1) /M _(i+1
) −OFS _(i+1) …Recalculate using the formula (11) and immediately correct the rolled position.

On the other hand, from the (i+2)th stand onwards, the entrance side plate thickness prediction error is assumed to be zero as mentioned above, S′ _p(i+j) =h _p(i+j) −F′ _p(i+j) /M _(i+j
) −OFS _(i+j) … Correct the roll position using the formula (13). Note that j=2,
3. It is...

This rolling position correction operation is repeated in the same way each time the material to be rolled is bitten into the downstream stand. Such a correction procedure is shown as a flowchart in FIG.

As described above, according to the present invention, the plate thickness or plate thickness deviation of the rolled material on the exit side of one stand, and the deformation resistance of the rolled material or its deviation are determined from the actual measured values of the rolling force and the rolling position, and Based on the above deformation resistance or its deviation, calculate the correction coefficient for the average deformation resistance to be corrected in the next stand or subsequent stands, and use this correction coefficient and the actual plate thickness value at the entrance side of the stand to calculate the Since it is configured as a plate thickness control device that adjusts the rolling position so that the side plate thickness becomes the target plate thickness, it is set to the value obtained by schedule calculation before the rolled material is caught in the first stand. After that, each time the rolled material is bitten by each stand, the prediction error of the average deformation resistance, which is a constant for the plastic deformation of the rolled material, and the exit side plate thickness error are calculated based on the actual measured values at that time, and these actual measured values are calculated. When calculating the correction of the rolling position of the downstream stand using the average deformation resistance correction coefficient obtained from
As the rolled material moves away from the stand, it is possible to change the weight and make corrections to suit the actual situation, making it possible to obtain a product with a target thickness with high accuracy.

[Brief explanation of the drawing]

FIG. 1 is a curve diagram for explaining the principle of the present invention;
FIG. 2 is a schematic diagram showing a plate thickness control device for a rolling mill according to the present invention, and FIG. 3 is a flowchart for explaining its operation. 1a, 1b: Rolls, 2a, 2b: Rolling position detection control device, 3a, 3b: Rolling force detection device.

Claims (1)

[Claims] 1. From the predicted rolling force of the i-th stand obtained by schedule calculation and the predicted deformation resistance Kpi obtained from the thickness of the material to be rolled, the actual rolling force at the time of rolling, and the thickness of the material to be rolled. Determine the deformation resistance correction coefficient TRENDi from the obtained measured deformation resistance K _Ai . However, saphitx Ai indicates the actual measured value of the i-th stand, Pi indicates the predicted value of the i-th stand,
F is rolling force, W is plate width, R′ is flat roll radius,
H is the inlet side plate thickness, h is the outlet side plate thickness, and Q is the pressure function. A plate thickness control device for a rolling mill, characterized in that the rolling mill position is corrected based on this deformation resistance correction coefficient. 2. A plate thickness control device for a rolling mill, characterized in that the rolling position after the i+1th stand is corrected based on the average value of deformation resistance correction coefficients derived for each stand upstream from the i-th stand.