RU1799648C - Slab width reduction method - Google Patents

Abstract

Usage: hot rolling of ingots in the roughing group of stands of a broadband mill. SUMMARY OF THE INVENTION: a slab is rolled in a universal stand with controlled compression, selected according to mathematical dependence. In the subsequent stand, rolling is carried out with the maximum allowable compression in vertical rolls. 1 tablet, 1 ill.

Description

 The invention relates to the processing of metals by pressure, mainly to the hot rolling of continuous slabs in the rough group of stands of a broadband mill.

The aim of the invention is to increase the productivity of the process by intensifying the deformation of the slabs in width.

The goal is achieved in that in a method involving rolling in universal stands with regulated compression in vertical rolls, the amount of compression in vertical rolls of the previous (i-th) universal stand is set from the condition:

0.3 in | (ДУ ° 85ехР (-0.065х.

 Ljbol

You

xAVv1Ra + DVS | -DVsT + DVv, Н§ |

  +1 +1

VNG

where D VV - compression in the vertical rolls of the 1st stand, mm;

HOI, Boi thickness and width of the roll at the entrance to the 1st stand, mm;

DB is the diameter of the vertical rolls of the 1st stand, mm;

D Bci, D Sun PC-free broadening on the main part and the front end of the roll during compression in the horizontal rolls of the 1st stand, respectively, mm;

D VVN (- forced broadening, mm; D - allowable compression in the vertical rolls of the (+1) th stand with the steady rolling process, mm;

Д Ввз) +1 - permissible compression in vertical rolls of the (1 + 1) th stand along the angle of capture when gripping the front end, mm, and rolling of the roll in vertical rolls of the subsequent (1 + 1} th stand is carried out with acceptable compression.

The drawing shows the experimental dependence of the front end of the roll on the width at the outlet of the unial stand (D G1) when changing the compression in vertical rolls (D BBi) for rolls with different initial widths (curves 1, 2 and 3) and fixed horizontal settings rolls. Vertical line 4 respectively (L

WITH

CH Yu Yu O SO

Meets the restriction of reduction in vertical rolls when grabbing A. The horizontal line 5 cuts off on the ordinate axis a value equal to the allowable compression during the steady-state process in the vertical rolls of the second universal stand D BBu. The ordinate axis is drawn perpendicular to this line with the beginning at the intersection point, on which the value of the allowable compression is depicted when grabbing the second in the vertical rolls. it is necessary to form a narrower peel at the exit from the first stand, and the size of the iron should not be less than the difference between the allowable compression of the main part and during capture, i.e. Дм Д ВцзЬ- Fulfillment of this condition will allow at the front end not to exceed the allowable compression by capture conditions. Methodically, using the nomogram shown in the drawing, the determination of the rolling parameters in the vertical rolls of the first and second stands is carried out as follows. Having set the maximum reduction according to the grip condition on the ordinate axis D, draw a line 6 parallel to the abscissa axis DVV1, which cuts off the necessary narrowing of the front end of the roll on the ordinate axis D-1, which ensures the capture and rolling of the roll in the vertical rolls of the second stand at the maximum compression x (permissible by the capture condition at the front end - Д ВВ3 and permissible for the steady-state process on the rest of the roll - D. Lowering from the point of intersection of the specified line 6 with curves 1. 2 or 3 lines to the axis D BB1, define corresponding crimping in the vertical rolls of the first stand to obtain, for a given compression in the horizontal rolls of this stand, the desired amount of front end tension in width at the exit of the stand.

The ironing of the front end of the roll at the outlet of the reducing unit (universal stand) is subject to the following relationship:

Dm d b | + (D Bci - ICE | PC) +

+ D BBHI, (2) where LW | - ironing of the front end of the roll at the exit from the vertical rolls, mm;

D Bci, D BCinK - free broadening on the main part and the front end of the roll, respectively, mm;

D BBHi - forced broadening, mm.

Parameters included in expression (2). are determined by the following empirical relationships:

1 L, 0.3 | i (fi) ° 85exP (-0.065 x xAE4DBl); (3)

HЈi

AT

ICE | Cop | D Hi (0.28 -0.012 i +

+ 0.585

Nam Hoi

we

(4)

NAM

D BC | PC D Bci 1 + 130 (3 -) x

By

Hoi

Bol,

Er1

 fci-M} W

A0-1 HOI / (he /

1.75

(5)

0.8 KK 0.786 + ABBi-5pX

DVvn

/ 0.0142 4.84

(€ ,.

eii

(6)

5

0

5

0

5

0

5

where Hot, Нц, Д Hi are the thicknesses at the inlet, outlet, and compression in horizontal rolls, respectively;

Dr | -diameter of horizontal rolls;

Kci - coefficient taking into account the structure of the metal;

Kk - coefficient taking into account the shape of the caliber of the vertical rolls of the reducing unit.

An example of a specific implementation of the proposed method is shown for the conditions of the under construction broadband mill 2500 of the Novolipetsk Metallurgical Combine, the draft group of which, according to the technical design, includes two successive reducing units (universal stands No. 1 and No. 2). The rolling diameter of vertical rolls with DBi DB2 panel gauges is 1,400 mm, of horizontal rolls Dri Dr2 1,600 mm. The values of the coefficients of formulas (4) and (6) are Kk 0.5; KC1 0.2; Ks2 0.6. The rolling parameters in vertical rolls were determined for the rolling conditions of the steel slabs of StZspU with a heating temperature of 1240 ° C, an initial thickness of 250 mm, a width of 1370, 1850 and 2250 mm. The thickness of the roll at the exit of the horizontal rolls is 200 mm for the first and 150 mm for the second stand,

The allowable compression in the first vertical rolls is determined by the gripping conditions. For a given diameter, it will be defined as

D DB1 (1).

where a is the allowable gripping angle for calibrated rolls. ai 28 °.

Consequently, D 164 mm.

In the second vertical stand, the allowable compression during gripping will also be 16 mm wide, the allowable compression of the main part during the steady rolling process is limited by the moment of rolling and is D 223 mm.

In the upper part of the graph, line 5 shows the allowable compression during the steady rolling process in the second vertical rolls D 22BU 223 mm. Sinking down along the D axis by a value of D 164 mm by line 6 we cut off the necessary narrowing of Dg1 59 mm on the axis Dg1. The intersection points with curves 1, 2, and 3 determine sufficient reductions to obtain such a narrowing. For B0 1370 mm - D Bv1 80 mm; In 1850 mm - D BB1 60 mm; B0 2250 mm -D BB1 50 mm. Having performed the crimping in the first vertical stand, not less than those defined above, we remove the restrictions on the capture in the second vertical rolls. Consequently, the allowable compression in them will be D BB2 223 mm. To minimize the width in two cages, the following reductions can be made: D BB1 160 mm; D BB2 220 mm. According to the prototype method, compression in the second vertical rolls is set equal to the front end after the first stand, i.e. the compression mode in vertical rolls will be as follows:

. for slab Vo 1370mm-D BB1 160mm; D BB2 92 mm;

for slab ВО 1850 mm - Д ВВ1 160 mm; DVV2 126mm;

. for slab Вo 2250 mm - Д Вв1 f60 mm; DVV2 148mm.

The compression in the second vertical rolls for the prototype method is determined according to the schedule (shown by arrows).

The decrease in slab width was determined by the formula

D V D VV1 + D VV2 - D VVN1 - D VVN2-DVS1-DVS2. (7)

Comparative results of the claimed method and the prototype method are presented in the table.

The data presented indicate the possibility of gradation of slabs in width

when casting on a continuous casting machine through (180-200) mm when using the prototype method in rolling technology and 260-300 mm for the claimed method, i.e. the assortment step is 1.4 times greater when implementing the proposed method. This makes it possible, firstly, to increase the minimum width of cast slabs by 100 mm and, secondly, to reduce the number of standard sizes of slabs in width, as a result of which the productivity of the caster mill complex can be increased.

 rumula of the invention A method of reducing slabs in width, including rolling the slab in universal cages with regulated compression in vertical rolls, characterized in that, in order to increase the productivity of the process by intensifying the deformation of the slabs in width, the amount of compression in vertical rolls preceding i-th universal stand is set from the condition

k2, (R l0 85 0.3 N ° BiJ exp (-0.065 x

b0 |

hdvv | You + ICE | DvpG + DVvn)

Hoi

 D +1 - DVVz (+ 1,

where D BB | - compression in the vertical rolls of the 1st stand, mm;

Hoi, Boi - thickness and width of the roll at the entrance to the i-th stand, mm;

DB | - the diameter of the vertical rolls of the 1st stand, mm;

ICE (, Д ВС | PC - free broadening on the main part and the front end of the roll during compression in horizontal rolls of the th stand, respectively, mm;

D BBn1 - forced broadening, mm; D — permissible compression in the vertical rolls of the (H-1) th stand with a steady rolling process, mm;

D is the permissible compression in the aertical rolls of the (1 + 1) th stand along the angle of capture when capturing the front end, mm, and rolling of the roll in the vertical rolls of the subsequent (H-1) th stand is carried out with acceptable compression.

Comparative data on reducing the slab width in two reducing (universal) cells