JPH02258105A - Method for deciding forward ratio in hot finish rolling - Google Patents

Abstract

PURPOSE:To decide an adequate forward ratio by averaging the forward ratios obtained by calculating re-regression value of sheet velocity at outlet side of rolls and regression value of peripheral velocity of the rolls in hot finishing mill. CONSTITUTION:At the time when tension of a rolling material 4 is stabilized by tip part thereof into a coiler 7, the sheet velocity of the rolling material 4 with a non-contact type velocimeter 3 arranged at outlet side of the rolling roll 2, and number of revolution for the roll with a roll revolution counter 5 fitted to the rolling roll 2, are measured at the minute interval for the prescribed time to obtain primary regression value respectively. Successively, by using the regression values, the whole measured values of the sheet velocity is statistically processed and the abnormal measured values are omitted to obtain the re-regression value and further, the re-regression value of the sheet velocity and the regression value of the peripheral velocity of the rolls are calculated to obtain the forward ratios and these ratios are averaged. By this method, the sheet thickness control having high accuracy can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for determining the advance rate in hot finish rolling.

<Prior Art> Setting the rolling load is one of the important factors in controlling the plate thickness during hot finish rolling using a hoshito strip mill.

Conventionally, various theoretical formulas for predicting the rolling load have been proposed, but when using these theoretical formulas, it is necessary to estimate the deformation resistance of the strip and the friction coefficient between the rolling roll and the strip surface. However, since it is difficult to actually measure the friction coefficient, the friction coefficient is usually calculated backwards using the rolling load theoretical formula, but in this case, errors are accumulated in the friction coefficient, resulting in a lack of accuracy. That was the reality.

Therefore, in recent years, a method has been used in which the advance rate is measured in the rear stand of a rolling mill and the coefficient of friction is determined from the value of the advance rate. As an example, the paper 1. Hot stripping process, 2. Optimal setting control method for rolling (2) J (1981 Spring Lecture on Plastic Working, N.
o, 108. As reported in 1984 (held in Naishi City, May 16-18, 1984), the rolling material exit speed at the rolling roll exit side ■8. Assuming that the roll circumferential speed at that time is 8, the advance rate f is expressed by the following equation (1).

r −(VS vll) / ”□−−−−−−
-(1) Then, by measuring the time taken for the rolled material to pass between the stands, the distance between the stands can be determined! 5 is the roll circumference as ■,・t! , can be expressed as VR-t, so the above equation (1) can be converted into the following equation (2).

f-(l, /p, R)-1---(2) Therefore, since the distance between the stands, l, is known, l''-le circumference! 8
If this is obtained, the advanced rate f can be determined.

However, since the shape of the tip of the actual rolled material varies, it is difficult to determine the timing at which the tip of the rolled material is bitten by the stand. This figure shows an example of the relationship between the advance rate measured at only one point and the rolling reduction rate determined from the theoretical formula of the rolling load, and it can be seen that the variation is very large. Therefore, it can be said that it is difficult to obtain a reliable value by measuring the advance rate at only one point.

<Problems to be Solved by the Invention> The present invention has been made to solve the above-mentioned problems, and aims to provide a method suitable for determining the advance rate in hot finish rolling. purpose.

<Means for Solving the Problems> The present invention provides a means for measuring the plate speed of a rolled material measured by a non-contact type speedometer disposed on the exit side of a rolling roll of a hot finishing mill, and a speed meter attached to the rolling roll. In this method, when the tip of the rolled material is wound around the coiler and its tension is stabilized, the plate speed is determined at minute intervals. It is not possible to accurately measure the passing time between stands using the Japanese method, and there is a risk that the measurement error will be very large, especially in the latter stands of the finishing mill because the speed of the rolled material is high.

On the other hand, as shown in FIG. 6, there is a
Attach the speed 3 of the laser method disclosed in Japanese Patent No. 572, etc., and measure the exit speed 5 of the rolled material 4, and set the rolling roll 2 at a rotation speed of 15 using a pulse generator, for example. There is a method of taking (=j), measuring its rotational speed N, and calculating the advance rate f using the following equation (3).

f-(V, -πD-N)/πI]・N = (3) where, D: Roll diameter However, even with this method, in the early stage of rolling, the rolled material may be bent due to waving, and mill speed compensation may occur. If the speed of the rolled material fluctuates due to such implementation, measurement errors will occur. Furthermore, the influence of skin marks cannot be ignored during rolling or in the later stages of rolling.

- Measure the circumferential speed of the roll for a predetermined period of time, apply linear regression to the measured values of the measured plate speed and roll circumferential speed to obtain a regression value, and then use the regression value of the plate speed obtained to calculate the plate speed. Statistically process all measured values of speed to remove abnormal measured values, perform regression again to obtain a re-regression value, and then combine the obtained plate speed re-regression value with the roll circumferential speed regression value. This is a method for determining the advance rate in hot rolling, which is characterized by calculating the advance rate and averaging it.

Function> As shown in FIG. 1, a rolled material 4 such as a strip rolled by a finishing mill 1 is normally passed through a mill 1-run cooling device 6.
While being cooled, it is rolled up in a coiler. During the finish rolling process, the advance rate f of the rolled material 4 is measured using the advance rate measuring device having the same configuration as that shown in FIG. 6 above.

That is, the plate speed of the rolled material 4 is measured by a non-contact speed meter 3 installed on the exit side of the rolling rolls 2 of the finishing rolling mill 1, and the plate speed of the rolled material 4 is measured by the roll rotation speed meter 5 attached to the rolling rolls 2. The detected roll rotation speeds N are respectively input to the calculation device 8.

Therefore, the arithmetic device 8 calculates the radius of the rolling roll 2 and the roll rotation speed N, which have been input in advance, to obtain the roll circumferential speed V11 (-πD-N), and then the
1) The advanced rate f is calculated using the formula.

The arithmetic processing procedure of this arithmetic device 8 will be explained below.

■ The point at which the tip of the rolled material 4 rolled by the second rolling mill 1 is wound up by the coil rough and the tension becomes steady and the constant mass flow law is established, for example, several seconds have passed from the start of winding. At the timing, the plate speed VSt and the roll circumferential speed (1) are measured at the sampling time ΔL (for example, O, is).

■ Then, continue measuring the amount for a certain period of time (for example, 5 seconds), and obtain n measured values.■3. .

(1) Perform linear regression for 8 to find regression values (2)Sr+VRr at each measurement time.

■ Then, using the n measured values VSt of plate speed ■ as targets, skid marks that appeared on the rolled material 4 and the advanced rate [representative of the mass flow Anhara that occurs during the transition period of Lupa control]
Determine as.

The above processing procedure is summarized in FIG.

Further, FIG. 3 shows the relationship with the number of samplings n when the average advanced rate factor 1 is determined using the present invention.

As is clear from this figure, when the number of samples is less than 10, the average advance rate r varies greatly;
For 10 or more pieces, although there is some variation, the width is small;
Furthermore, it is almost constant for 100 or more pieces.

In the above explanation, the plate speed needle 3 is attached to the exit side of the rolling roll 2, but the present invention is not limited to this, and if it is attached to the entry side of the rolling roll 2, It goes without saying that it is also possible to obtain the average backward rate instead of the average forward rate (Example) Is a laser Doppler plate speed needle installed on the exit side of the final stand of the finishing mill of a hot strip mill? = t Lj, when measuring the plate speed of a rolled material with material SAE 1008 and thickness: 2.3 mm to find the advance rate, in order to remove the influence of the present invention's high speed, etc., Regression value■5. ．． is used to statistically process whether the following equation (4) is satisfied.

v, −vs, <ε −−−−−−−−−−−−−−−~
−−−−−−−−−−(4) Here, ε is a control limit value, for example, the regression value ■8. 3σ (here, σ: standard deviation value).

If the above equation (4) is not satisfied, that is, (vsr+
Measured value exceeding the value of ε)■3. (for example, m pieces) are removed and the regression value V3r and fftA are obtained.

(2) Furthermore, regression is performed again on the (nm) measured values (■□) and the m regression values VSr that have been replaced by this statistical processing to obtain re-regression values (2) and r.

■ Then, the re-regression value ■8 of the board speed ■ obtained in step ■. ', and the regression value vRr of the roll circumferential speed (7) already obtained in step (2), calculate n advance rates rt by calculating based on the equation (11) described above.

(2) Furthermore, the n advancement rates f+ obtained in step (2) were averaged, and this average advancement rate TI was measured using a four-point measurement method for the rolled material.

From the point in time when 10 seconds have passed since the rolled material started being wound up by the coiler, the plate speed and roll circumferential speed were measured for 5 seconds with a sampling time of 0.1 s to obtain 50 pieces of measurement data.
Statistical processing was performed according to the procedure shown in the figure to determine the average advancement rate. The control limit value ε at this time was set to 3σ.

The relationship between the obtained average advance rate f and the rolling reduction rate r derived from the theoretical formula of the rolling load is shown in FIG. 4(a) using the friction coefficient μ as a parameter. In the figure, for example, the rolling reduction rate r is 1
In the case of 5%, the average advanced rate [variation range is about 1.5%]
It can be seen that it is.

On the other hand, the advanced rate r is determined by the conventional one-point measurement method,
When the relationship with the rolling reduction rate r was determined in the same way, the results are shown in Figure 4 (
As shown in b), the variation width 1 of the advance rate f was approximately 40% when the rolling reduction rate r was 15%.

As is clear from these results, it can be seen that the multi-point measurement method of the present invention has much smaller variations than the conventional example.

<Effects of the Invention> As explained above, according to the present invention, the advance rate is measured at multiple points and subjected to statistical processing, and then the average value is used, so highly accurate plate thickness control is possible. can be realized. Therefore, it greatly contributes to improving product quality and yield.

[Brief explanation of drawings]

Fig. 1 is a block diagram schematically showing an example of an advanced rate measuring device according to the present invention, Fig. 2 is a flowchart showing the processing procedure of the method of the present invention, and Fig. 3 shows the average advanced rate and the number of samplings. 4 is a characteristic diagram showing an example of measuring the advanced rate by the method of the present invention. FIG. 5 is a characteristic diagram showing an example of measuring the advanced rate by the conventional method. FIG. 6 is a characteristic diagram showing an example of measuring the advanced rate by the conventional method. FIG. 7 is a block diagram schematically showing an example of an advanced rate measuring device, and FIG. 7 is a characteristic diagram showing an example of measuring the advanced rate by a conventional method. 1... Finishing rolling mill, 2... Rolling roll. 3... Plate speed needle, 4... Rolled material 5... Roll rotation speed meter, 7... Koirae 8... Arithmetic device.

Claims (1)

[Claims] The plate speed of the rolled material measured by a non-contact speed meter placed on the exit side of the rolling roll of the hot finishing mill, and the roll circumferential speed measured by the roll speed meter attached to the rolling roll. In the method of determining the advance rate based on the method, when the tip of the rolled material is wound around the coiler and its tension is stabilized, the plate speed and the roll circumferential speed are measured at minute time intervals for a predetermined period of time. The regression values are obtained by performing linear regression on the measured values of plate speed and roll circumferential speed, respectively, and then statistical processing is applied to all measured values of plate speed using the obtained regression value of plate speed. Remove abnormal measured values and perform regression again to obtain a re-regression value, and further calculate the obtained plate speed re-regression value and the roll circumferential speed regression value to obtain an advance rate and average it. A method for determining the advance rate in hot finish rolling, characterized by: