RU2068308C1 - Method for reverse rolling of thick sheets from slabs - Google Patents

Abstract

FIELD: manufacture of rolled products in reversing mills. SUBSTANCE: method involves broadside first and second diagonal rolling, with slab longitudinal axis being turned for assigned angle through two reversing passes, with total relative reduction extent for two adjacent reversing passes being set within the range of 0.15-0.25 and absolute reduction extent for two passes being set as equal. Assigned angle θ is determined by formula recited in Specification. Method is efficient for rolling in thick sheet mills, with ratio of slab initial thickness and ready strip width exceeding 2.3-2.5. EFFECT: increased efficiency, wider operational capabilities and improved quality of rolled sheets. 2 cl, 2 dwg, 1 tbl

Description

 The invention relates to the field of rolling production, namely to rolling thick sheets on reversing mills.

Φ₂= arctg (μ₂tgθ₂)+arctg[μ₂tg(Φ₁-θ₂)], (2)
где Φ₁ и Φ₂ углы между сторонами раската в плане после прокатки на первую и вторую диагонали; θ₁ и θ₂ углы поворота продольной оси раската при задаче в валки; μ₁ и μ₂ коэффициенты вытяжки при прокатке на первую и вторую диагонали.There is a method of rolling thick sheets [1] according to which, in order to reduce the metal consumption for trimming due to the rectangular shape of the roll, expansion rolling is carried out with the alternate task of rolls to the first and second diagonals at a given angle θ. The angle q is determined from the relations

Φ ₂ = arctan (μ ₂ tgθ ₂ ) + arctan [μ ₂ tg (Φ ₁ -θ ₂ )], (2)
where Φ ₁ and Φ _{2 are the} angles between the sides of the roll in the plan after rolling to the first and second diagonals; θ ₁ and θ ₂ rotation angles of the longitudinal axis of the roll when the task in the rolls; μ ₁ and μ ₂ are drawing coefficients when rolling to the first and second diagonals.

 The disadvantage of this method is that relations (1) and (2), which establish the angle of the problem, do not take into account the unevenness of the natural broadening in the corner sections of the slab depending on their location along the length and width of the slab, which determines the sequence of deformation during capture and exit from the rolls.

 According to the known method of rolling hoods and the angles of the problem on the first and second diagonals can be different, which contradicts the experimental data. The experimental data also indicate the existence of optimal values of the capture angles, the total compression between the grooves and the discreteness of the compression (the number of passes).

 The aim of the invention is to reduce the consumption of metal for trimming by obtaining a rectangular shape of the roll.

The goal is achieved in that in a method including broaching, tilting, broadening passages to the first and second diagonal with rotation of the longitudinal axis of the slab by the angle of the problem, determined depending on the total hood, the rotation of the longitudinal axis of the slab is carried out through two adjacent reverse passages, and the angle of the task the first and second diagonals are determined depending on the total relative compression for two adjacent reverse passages according to the formula
θ = 28- arctan ε _cm , (3)
where θ is the angle of the problem on the first and second diagonals of the slab, deg;
e _cm total relative reduction for two adjacent reverse passes.

 The total relative compression for two adjacent reverse passages is set in the range of 0.15 0.25, and the absolute compression in each pass is equal.

The proposed method is illustrated by graphs, where in FIG. Figure 1 shows the experimental curves of the dependence of the value of the coefficient of flow of metal into the cut To _p from the number of passes during rolling on each diagonal of the slab n _cm for various values of the angle of the problem θ and relative reductions in one pass e ₁ . As can be seen from the graphs, the minimum value of K _{p is} provided by two passes, and the degree of reduction of K _p increases with an increase in the task angle θ and a decrease in the relative compression in one pass.

In FIG. 2 shows the effect of the total relative compression for two adjacent reverse passages e _cm on the value of the metal flow coefficient K _p at different angles of the problem θ. In FIG. 1 and 2 it is seen that the optimal values of the angle of the problem q are in the range of 15 20 ^o , and the total relative compression for two adjacent reverse passes e _cm in the range of 0.15 0.25.

The conditions for rolling on a diagonal in two passes with θ more than 20 ^o and e _cm less than 0.15 are not optimal, because increase the rolling cycle by increasing the total number of passes, which leads to a decrease in mill productivity and metal temperature.

Depending on the value of the total relative compression for two adjacent reversing passes, the optimal angle of the problem is determined by the formula (3)
θ = 28-arctan ε _cm .
The method is as follows.

For several passes, the initial slab is rolled lengthwise to a predetermined length (broach). Turn over a slab at 90 ^o . Depending on the grade of steel, the value of the total relative drawing is set for two adjacent reversing passes when rolling at an angle (diagonal) in the range of 0.15 0.25. The lower limit is assigned when rolling high-strength steels, the upper ductile. Turn the slab for rolling on the first diagonal with the angle of the problem plus θ, determined by the formula (3). Perform two reverse passes with a given total relative compression e _{cm back} , evenly distributing the compression passes.

Turn the roll for rolling on the second diagonal, setting the angle of the problem minus θ. Perform two reverse passes with a given total relative compression. Turn over the roll at an angle of 90 ^o , combining the longitudinal axis of the roll with the axis of rolling. Perform several reverse passes to a predetermined thickness of the finished sheet.

In laboratory conditions, we performed a simulation of rolling a carbon steel slab on a plate mill with a simulation scale of 1 10. We compared the two series of plasticine samples of slabs with dimensions H _o x B _o x L _o 20 x 50 x 130 mm in horizontal rolls with a diameter of 100 mm.

All samples of each series in the first pass were rolled along the axis with a compression of DH 2.5 mm, then turned over at an angle of 90 ^o for subsequent expansion rolling. The rumbles of the first series were rolled by the proposed method. Preliminarily, the value of the total relative compression for two adjacent reverse passages for each diagonal ε _cm 0.23 was established. Before expansive rolling on the first diagonal, the peals turned at the angle of the problem, determined by the formula (3)
θ _cm = 28-arctg 0.23 = 28-13 = 15 ^° .
Two reverse passes were made to the first diagonal with 2 mm compression.

The peals were turned in the opposite direction by an angle equal to 2 • θ, for rolling to the second diagonal with a task angle of -15 ^o . Two reversible passes were performed with reductions of 1.6 and 1.5 mm.

 Expansion rolling of the second series of peals was performed by a known method (prototype).

определили Φ₁= 82,47^o, а затем по формуле (2), принимая Φ₂=90^o и μ₂=μ₁= 1,299, определили угол задачи θ₂=10^o.For comparability of methods, the angle of the problem on the first diagonal was also taken equal to 15 ^o and the total relative compression in two reverse passes was taken equal
θ ₁ = θ = 15 ^° ; ε ₁ = ε _cm = 0.23.
By the formula (1), given that

determined Φ ₁ = 82.47 ^o , and then by the formula (2), taking Φ ₂ = 90 ^o and μ ₂ = μ ₁ = 1,299, we determined the angle of the problem θ ₂ = 10 ^o .

They turned the rolls for rolling on the first diagonal at a given angle of 15 ^o , performed two reversible passes with reductions of 1.8 and 2.2.

The peals were turned in the opposite direction by an angle equal to θ ₁ + θ ₂ , for rolling to the second diagonal with the task angle θ ₂ = -10 ^o . Two reversing passes were made with reductions of 1.7 and 1.4 mm.

 After expansive rolling, the peals of the first and second series were measured, the side and end uneven edges were cut. The trimmings were weighed, and the average trimmage of peals of each series was calculated. Based on the ratio of the initial mass of the slab to the mass of the trim, the metal flow coefficients were determined for each rolling method.

 The data on the rolling of two series of slabs are summarized in the table.

The table shows that the rolling of thick sheets by the proposed method is characterized by a lower metal consumption (K _p 1,1) than by the known method (K _p 1,2).

 The proposed method is effective for rolling conditions on plate mills with a ratio of the width of the original slabs to the width of the finished strips more than 2.3 2.5.

Claims (2)

1. The method of reversing rolling of thick sheets of slabs, including broaching, tilting, broadening passages on the first and second diagonals with rotation of the longitudinal axis of the slab by an angle of the problem, characterized in that the rotation of the longitudinal axis of the slab is carried out through two reverse passes, and the angle of the task is on the first and the second diagonal is determined in two adjacent reverse passages according to the formula
θ = 28-arctgε _cm ,
where θ is the angle of the problem on the first and second diagonals of the slab, deg;
e _cm total relative reduction over two adjacent reversing passes.  2. The method according to claim 1, characterized in that the total relative compression for two adjacent reversible passages is set in the range of 0.15 0.25, and the absolute compression along the passages is equal.

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