SU1588450A2 - Method of rolling slabs on sheet mills - Google Patents

Abstract

The invention relates to rolling production, in particular, to rolling continuous slabs with reduction. The purpose of the invention is to increase the yield of rolled steel by reducing the length of the ends of the bar with a width less than the nominal one. The method consists in rolling in vertical rolls (BB) 0.5-0.8 widths of slabs in zones of unsteady rolling process with decreasing difference in rotational speeds of explosives and horizontal rolls when rolling the back end and increasing when rolling the front end according to , providing a linear increase in the backpressure force in the rolled strip from the zero at the end of the unsteady process zone to the maximum at its beginning (i.e., at the ends of the slabs). 4 il.

Description

The invention relates to rolling production, in particular to the rolling of cast-line casting machines with reduction.

The purpose of the invention is to increase the yield of prokata by reducing the length of the ends of the roll with a width less than the nominal one.

FIG. 1 shows the shape in terms of the end of rollout after rolling in vertical rolls (thin lines show the shape of the rolls during rolling without backwater, dash-dotted - when rolling with a rapid increase in backwater and dotted - with an increase in backwater according to the proposed method); in fig. 2 - form in terms of the end of roll out after rolling in vertical and horizontal rolls (the main line shows the end contour during rolling without backwater, dash-dotted - when rolling

with unregulated rapid increase in backwater and dashed - according to the proposed method); in fig. 3-schema-reduction with back pressure (in the direction of rolling) the end of the roll; in fig. 4 - the same front.

The method is carried out as follows.

If the reducing unit has vertical rolls in front of horizontal ones, the rear end is rolled in a first pass with a support (Fig. 3). The slab is rolled simultaneously in vertical and horizontal rollers. Moreover, the speed of the vertical rolls set, based on the equality of the second volumes of metals in both cages x. As a result, there are no longitudinal forces in the strip. When the rear mowers remain unrolled

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 sl o

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a length of 0.5-0.8 slab width, the speed of the vertical rolls begin to increase according to

„,,„, | т (, к,). (1)

where the + sign refers to the rear rolling, and the - sign refers to the front ends of the roll;

vBBx speed of vertical rolls at a distance X from the end rolled in vertical rolls, m / s;

X is the distance from the end of the roll, rolled in vertical rolls to the line Connecting the centers of the vertical shafts, || s, mm;

i VTB - speed of horizontal rolls, m / cm;

RGV cross-sectional area of the roll at the exit of the horizontal rolls, mm;

FBB is the cross-sectional area {roll out at the exit of the vertical rolls,

Ki is the coefficient for adjusting the speed of vertical rolls, 03-0.05;

 length coefficient of unsteady process, 5-0,8;

B is the width of the slab, mm, obtained on the basis of the experimentally established fact of a sufficiently good compensation for the reduction of sagging in the unsteady process zone with a linear growth pressure of the backwater. , which reduces the value of nakato according to experimental data by 20-30%. At the same time, there is a partial alignment of the width along the length of the roll, and consequently, a decrease in the length of the rear ends D t2 with a width less than the nominal one (Fig. 2) by 50-60%.

With the increase in backwater according to the proposed method, a new effect arises - a reduction in the length of the ends with a width less than the nominal width, due to which the yield increases.

After the first pass, the vertical and horizontal rolls are reversed and, in the second pass, the front end rolls with support in the direction of rolling. At the same time, the front end rolls with the maximum support required to completely eliminate the overrun (as in this case, the conditions for capturing the amount of backwater are not limited), and subsequent sections of the roll, in accordance with relationship (1), are rolled with decreasing support (due to the increasing speed differences of vertical and horizontal rolls). At a distance of 0.5-0.8 slab width from the front end, the backwater becomes zero by increasing the difference in rotational speeds of the previous and next pairs of rolls to a value corresponding to the condition of equality of the second volumes of metal in the rolls (Fig. 4), Due to the increase in the difference in rotational speeds of the rolls, proportionally to the increase in sagging on wide edges, the length of the ends with a width less than the nominal width is reduced by 90-100%, i.e. the wideness is almost completely eliminated.

The proposed slab method on sheet mills provides an increase in the yield of rolled metal by reducing the length of the ends of the bar with a width less than the nominal one.

Claims (1)

Invention Formula The method of rolling slabs on sheet mills in aut. St. No. 990352, characterized in that, in order to increase the yield of rolled products by reducing the lengths of the roll ends with a width less than the nominal, the rear end of the roll is rolled when the difference in the rotational speeds of the vertical and horizontal rolls decreases, and the front end of the rolls is rolled by increasing the difference in the speeds of rotation of these rolls, determined by BBx VrB V -W) FBB К2В where the + sign refers to the rear rolling, and the - sign refers to the front ends of the roll; vBBx is the speed of vertical rolls at a distance X from the end rolled in vertical rolls, mm / s; VTB - speed of horizontal rolls, m / s; RGV - the cross-sectional area of the roll at the exit of the horizontal rolls, mm; FBB is the cross-sectional area of the roll at the exit of the vertical rolls, KI - speed adjustment factor for vertical rolls, .03-0.05; K2 - coefficient taking into account the length of the unsteady process zone,, 5-0.8; B — width of slab, mm; X is the distance from the end of the roll, rolled in the vertical rolls, to the line connecting the centers of the vertical rolls, mm.