SU608574A1 - Method of automatic strip thickness control in continuous wide-strip rolling mill - Google Patents

Description

The total value in each stand is compared with a value proportional to the position of the pressure screws of the same stand, and when these values are misaligned, the gap between the working rolls is changed to eliminate the indicated mismatch in each stand, and the gaps between the work rolls of all stands are adjusted by the output thickness deviation from of a given value, the distribution of the impact on the values of the inter-roll gaps of the stands in proportion to the constant coefficients corresponding to each stand, the gaps between the working rolls of each the stands of the finishing group of the mill are additionally changed by the amount of thermal expansion of the rolls, which is determined by the formula

DL, K and at .Kt (t) - X

x (+ Kir, +

+ V, / C.l-exp (-) J}.

where Kh, Ki are the proportionality coefficients for a given t stand; ui - acceleration of the work rolls i stand,

t is the current rolling time, s; nr is the start time of rolling with acceleration, s;

Ti is the time constant for stand t, s;

ViH - the initial (filling) speed of the work rolls i stand, m / s;

A / 1 {- value of additional variation of the gap between work rolls i stand, mm.

Example. A strip is rolled on a continuous sheet mill. Nominal output thickness h 2.5 mm.

The technological mode of each stand is given in the table.

After rolling a part of the strip 200 m long, the mill starts accelerating with an acceleration of 0.33 m / s for the last stand.

During the rolling process, the pressure is measured.

rolling in each stand, determine the amount of its deviation from a given value and compare the deviation with a value proportional to the position of the pressure screws of the same stand. When these values are misaligned, the gap between the work rolls is changed until the specified mismatch is eliminated.

At the same time, the output thickness is measured and the gaps between the rolls are adjusted according to its deviation from the set value. At the same time, the gaps between the working rolls of each stand are additionally changed by the amount of thermal expansion of the rolls. The start time of acceleration is 200/9 L 22 s. Additional signals, for example for 5 and 6 stands, are determined by the formula

and, K, {0.26 0.1 (- 22) - O L - 20 X

Xe 2o- + 0, l-20I + 6.0.0, l l-e- / 2oj}; U, Kk {0.28 0.1 (-22) -0.1-20 X

- / - 22 20

Heh + 0, l-201-f 7.).

Values of hectares, s; Ks, / St. 0.1.

According to these signals, the gaps between the working rolls of all the stands of the finishing group are changed in the direction opposite to their thermal expansion, i.e., the total changes in the gap are 0.

In this case, the signal from the thickness gauge at the mill output reflects only thickness deviations caused by wear and inaccuracy of the initial setting.

Using the proposed method of automatic adjustment of the strip thickness provides the following advantages:

reduction of strip thickness variation;

increase the stability of the rolling process;

simplification of the operator’s work and reduction of emergency situations during the automatic thickness adjustment.

Claims (2)

1. Meerovich IM, and others. Improving the accuracy of sheet metal, M., 1969, p. 175. 2. Leonid-Kanevsky E. V. “On the distribution of correction signals when adjusting the strip thickness in a continuous rolling mill. Sat “Automation of rolling mills, In-t Automation. Kiev, “Naukova Dumka, 1974, p. 92