SU1764723A1 - Method for hot-rolling of strips - Google Patents

Description

one

(21) 4653174/02 (22) 02.22.89 (46) 30.09.92. Bul №36

(71) Institute of Ferrous Metallurgy and Karaganda Metallurgical Plant

(72) T.-A.S. Saysimbinov, L.V.Timoshenko, S.A.Burlakov, A.G. Svychinsky, V.M.Add Kin, V.L. Mazur, O.Soskovets and A. .A.Chmelev (56) Mazur V.L. and others. Rational cross-sectional cross-sectional shape. Steel, 1988, No. 3, p. 50-54.

USSR Author's Certificate No. 1690873, cl. B 21 B 1/26, 1989.

(54) METHOD FOR HOT STREAMING

(57) The invention relates to the processing of metals by pressure, in particular to sheet-rolling production, and can be used on a wide-strip hot rolling mill. The purpose of the invention is to improve the quality of the rolled strip for the cold limit by providing a rational cross-sectional shape. In the hot rolling method, which includes hot rolling the heating strip before rolling the main rolling strip, intended for the cold limit, the strip from the rolling strip with the ratio of thickness to width within (2.25-2.65) -10 is rolled after heating strip from 1/2 to 5/4 of the heating bands, 1 tab.

The invention relates to the field of metal forming, in particular, to sheet-rolling production, and can be used in the preparation of strips on a wide-strip hot rolling mill (SHSGP).

The aim of the invention is to improve the quality of the rolled strip for the cold limit by providing a rational cross-sectional shape.

The essence of the method is that between the volumes of heating bands (Gp), the total volume of rolled products (Gy) and the main bands (Go), the parameters of which vary in terms of the ratio of thickness to width of strip (HB), there are certain interrelations. In particular, the mass of the bands reaching for the cold limit, with the ratio CO

WITH

The thickness to width within 2.25, 65 is selected depending on the volume of the main strips. So for small volumes it is advisable to use a smaller value, including H / B 2.25 10, since for small volumes the influence of such factors as wear is small. However, even lower H / B values of 2.25 even under these conditions, when the rolled-in volumes are small, can still lead to a noticeable increase in the longitudinal thickness variation and, consequently, to a deterioration in the quality indicators of cold-rolled strips, for example, by flatness parameters. . A large value of this ratio up to N / V 2.65 is acceptable for relatively large volumes of main bands, when the thickness of the rolled in large volumes of the main bands, when the thickness of the rolled in largely depends on

VI

ABOUT

 VI

Yu

WITH

wear and heat convexity of the roll barrel, and the thickness of the roll are compensated for by factors that worsen the strip thickness variation. An even greater increase in the thickness of the N / B 2.95 rolled billet will lead to the fact that at the cold limit, the amount of non-planar stripes will increase due to the elastic deflection of the cold rolling mill rolls in the first cages, which in the latter develops as a parameter of the flatness . The ratio of the volume of the main bands and the heating bands with the limits of 1/2 G / GP 5/4 (or 0.5 G0 / GP 1.25) is aimed at stabilizing the thermal profile of the roll barrel and, as a result, reducing the variation of the thickness parameters during rolling . In this case, a smaller value of the ratio, including Go / Gp 0.5, is acceptable in the case when preheating the heating strip of increased thickness is rolled. If, however, we continue to reduce this ratio Go / Gp 0.5, then we may encounter the fact that even with such a gauge of heating stripes, the volume of the rolled strip with increased longitudinal thickness variation, and this ultimately proves to increase flatness defects in terms of coarseness. Large values of this ratio, including Go / Gp 1.25, are advisable to use if the volumes of the heating bands are relatively large, but an even greater increase in this ratio (Go / Gp 1.25), which may result in an increase in the number of bands with thickness variation, including even zero thickness variation and concave profile. And this, at the cold limit, will lead to the appearance of such a defect as a wavy edge, that is, to a decrease in quality.

The implementation of the method is illustrated by examples.

Comparative rolling was carried out at ShSGP 1700 (Table 1). The invented method was compared with the known one, in which the compared parameters ranged within:

23 Gp / G 33%; 2.2 G0 / GP 3.0. In this case, for comparison, the minimum limits of the known Gp / G2 method were taken to be 23% Go / Gp 2.2, since the averages and the maximal extreme values of the known method provided even lower results. In addition to the optimal values of the parameters of the proposed method, two levels of exorbitant values were also checked (Fri and Pv):

Method Level N / B, m Gp / G0 (0) G0 / GP

Hi2,2x10 ° 50,4

P52.7 xY 3 251.3

The check was carried out on the strips of the strip, going for a cold finish of 1000 mm width. Rolled rolled made on the so-called. leaf rolls where

0, the total volume of rolled strips was maintained at the same level and was 5000 tons in all the compared levels and variations of the rolling methods. The entire volume of the rolled strip was controlled by the level of heterogeneity and grouped within the selected ranges of heterogeneity. Then, the rolled strip was set for a subsequent limit on the cold rolling mill 1700. Cold rolled strip had

0 thickness 0.8 mm. Inspecting them for flatness defects made it possible to identify the sorting volumes of cold rolled strips. At the same time, it was established that between levels of different thickness

5, there are fairly close links. In particular, defects in the increased level of thickness variation corresponded to a smaller indicator of the method, which was manifested in defects in the taddiness. At lower levels

0 way to produce more low thickness, which led to defects such as edge waviness. At the same time, maximum volumes with optimal values of thickness variation (0.05-0.10 mm)

5 occurred at the average level of the claimed parameters of the method (P3), which was manifested in the minimum total volumes of flatness defects on the cold-rolled strips less than with the known (AND)

0% by 7.9%. The limiting values of the claimed method in one case (PC) confirmed the optimality of the lower bounds at which such a non-flatness defect was significantly manifested as coredness due to a high level of longitudinal thickness variation on the rolling, in another case ( (Ii) low spacing, down to the concave cross-section of the roll, which

0 led, ultimately, to increased volumes of wavy-edge defects. Both exorbitant levels (P1 and PB) turned out to be worse in terms of quality indicators than the known method (I), But in the optimal

Within the limits of the claimed method, a higher quality is achieved by reducing the longitudinal thickness variation in the rolled strip.

The main technical and economic advantage is the increase in the quality indicators of hot rolled strips.

Claims (1)

Claim method A hot strip rolling process including hot strip rolling and heating and subsequent rolling of a cold-rolled stock roll billet, characterized in that, in order to improve the quality of the rolled strip for cold, the results of comparative tests of the known (AND) and proposed (L) methods in terms of SHSGP 1700 Application: B, K and Ј - wavy edge, boxing and total flatness defects. This is done by providing a rational cross-sectional shape, after rolling strip heating strip with a ratio of thickness to width in the range (2.25 -2.65) in a volume of 1 / 2-5 / A volume of heat bands. /