RU1792759C - Method of controlling hot rolling of metallic strips in group of finishing stands of continuous rolling mill - Google Patents

Abstract

Usage: hot rolling strips in a continuous mill, Summary of the invention: during rolling; strips in the end group of stands of a continuous mill, the position of the pressure devices is changed depending on the deviation of the strip temperature from a predetermined value of the front of the stand in accordance with the above dependence. 1 tab.

Description

 ; The invention relates to metallurgy and can be used in the production of metal strips, in particular from mild steel and low carbon steel /

Known methods for controlling hot rolling, including fine hot rolling at a metal temperature of 750-1150 With strips of width 850-1450 mm from a thickness of a roll of 25-40 mm to a strip thickness of 1.8-1 {2 mm in a continuous group of 5 -7 quarto stands, to maintain the required nominal strip thickness and roll hi, a strip thickness and gofofil control system is used, which, based on the data of rolling efforts, the position of the pressure devices, the thickness of the roll, gives a task to move the baiters and the anti-bend system polo ..

However, a significant change in the temperature of the prototype roll before the finishing focus makes it difficult to maintain the required strip characteristics, which is aggravated by the fact that a defect compensation signal is formed in the presence of a geometry defect dhi. In addition, the control systems operate in a narrow (20-45 ° C) range of the temperature of the metal in front of the finishing group of the stands. A change in the system of maintaining measurement limits requires rolling stops. And to reduce productivity, rolling is partially carried out without regulation, which sharply worsens the geometry of the strips.

In addition, deviations of the roll temperature from the nominal values during prototype control lead to failure of the pressure devices and roll drive elements.

An increase in the expenditure coefficient due to the rejection of rolled products, the use of expensive control systems, cases of equipment failure and operation during the control of hot rolling according to the prototype lead to an increase in the cost of production.

The aim of the invention is to improve the geometric characteristics of the strips and reduce their cost.

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The proposed method for controlling the hot rolling of metal strips in the finishing group of stands of a continuous mill, including measuring the thickness of the roll before each stand, the impact on the pressing devices of the stands, differs from the prototype in that the deviations of the temperature of the strips in front of the finishing group of the stands from the set value are measured, and the effect the pressure screws are carried out in accordance with the expression

AqAt 7A17

(

xbVR-hio-Јi (5-) V7At7

where b is the width of the roll, mm;

R is the radius of the rolls, mm;

n is the number of stands in the group;

hio - thickness of the roll before the i-th stand, mm ;.

Ј g the magnitude of the deformation of the roll in the 1st stand,%;

At - deviation of the strip temperature from the set before the finishing group of stands, X; ., -.-, .. ..;.

Examples of the method.

Testing was carried out for the hot hot rolling of strips of electrical steel (0.4% Si), 1050 mm wide, 2.5 mm thick and 15 KP steel 1150 mm wide, 5 mm thick ..

After heating the slabs with a cross section of 165 × 1020 mm and 200 × 1120 mm to a temperature of 1150–1300 ° С, hot rolling of successively vertical and horizontal rolls of descaling agents was carried out in an expansion stand and on vertical and horizontal rolls of four universal stands. Next, the finish rolling was carried out sequentially in seven cells of the continuous group of mill 1700 of the proposed method. The nominal temperature of the roll of electrical steel is 1000 ° C,

and the nominal temperature of the roll of steel 15 KP is 1020 ° C. The width of the roll of electrical steel is 1050 mm, steel 15 KP is 1150 mm. Work rolls had a diameter of 700 mm. Nominal value of relative deformation Ј | and strip thickness h | 0 in stands for rolling and rolling of electrical steel were 36.7% and 30 mm, respectively

- 34.7% and 19 mm - 32.3% and 12.4 mm - 33.3% and 8.4 mm - 26.8% and 5.6 mm - 24.4% and 4.1 mm - 19 , 4% and 3.1 mm, and the values of ei and hj0 in the cells during rolling of steel 15 KP were equal to 33.5% and 40 mm, respectively -30.3% and 26.4 mm

- 29.3% and 18.4 mm - 28.5% and 13 mm - 22.6% and 9.3 mm - 20.1% and 7.2 mm - 13% and 5.75 mm. Some test results are shown in the table. For the purpose of comparison, a number of samples were tested according to the prototype. The table shows the calculated (P) values of the effect on the pressure screws (changing the position of the pressure devices from the nominal A qi) and experimental (E). It was found that when the proposed method is implemented, rolling of the entire length of the strips is guaranteed at minus tolerance (for electrical steel - 0.16 mm, for steel 15 KP - 0.50 mm), while according to the prototype there were deviations in the thickness of the strips for electrical steel

-4-P LPclm

2.5 ozb for steel ° 15 KP deviation not 5.0 - l,. Almost complete exclusion of rejection of strips by defects

geometry, the possibility of rolling without a complicated expensive system for maintaining the thickness of the strips reduces the cost per unit of production ..

Testing showed that the proposed method in comparison with the prototype improves the geometric characteristics of the strips by 50-85% and reduces the cost of manufacturing a unit of production by 1-15%.

Claims (1)

SUMMARY OF THE INVENTION A method for controlling the hot rolling of metal strips in the finishing group of stands of a continuous mill, including measuring the thickness of the roll before each stand, applying pressure to the pressing devices of the stands, characterized in that, in order to improve the geometric characteristics of the strips and reduce their cost, the temperature deviation is measured stripes in front of the finishing group of stands from a given value, and the impact on pressure the screws are in accordance with the expression Aq-y | 0.196x10 5x xbVR-hio-Ei (5-) V7Al7 where Aqi is the amount of movement of the pressure device of the 1st stand from the nominal level, mm; b - roll width, mm; R is the radius of the rolls, mm; n is the number of stands in the group; hpi- thickness of the roll before the 1st stand, mm; j bi - the magnitude of the deformation of the roll in the 1st stand,%; I At - deviation of the strip temperature from the set before the finishing group of stands, ° С. . Table continuation