RU2511159C1 - Wide strip manufacturing method - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: method involves heating of steel workpieces and their multipass crimping as to width and thickness in horizontal and vertical rolls. Improvement of the strip stability at its crimping as to width is provided due to the fact that when the ratio of the strip thickness to its width is not more than 0.20 during the rolling process, the strip is bent around the roller, the body length of which does not exceed 0.9 of the strip width, with its simultaneous crimping as to width in a bent state; with that, the angle of contact of the roller with the strip is at least 10°.

EFFECT: improving accuracy as to width of hot-rolled strips rolled on continuous wide-strip mills.

2 dwg, 1 tbl

Description

The invention relates to the field of metallurgy and can be used in the production of hot-rolled steel strips on continuous broadband mills.

A known method for the production of steel wide strips, including rolling slabs on a continuous broadband mill in the vertical rolls of the roughing group of stands, and the amount of lateral compression set by the proposed ratio [1].

There is also known a method of hot rolling of steel strips in a continuous broadband mill line, including heating the slab, its multi-pass alternating compression in width in vertical rolls and in thickness in horizontal rolls, the width reduction being carried out in five vertical roughing stands, with the compression in the first two vertical stands not more than 35%, and in the remaining 65-100% of the total reduction in width [2].

The disadvantages of the known methods [1, 2] are that they do not allow to reduce the width, which is formed during the rolling process in the finishing group of stands and is due to the broadening and shortening of the strip.

The closest analogue to the present invention is a method of hot rolling of steel strips in a continuous broadband mill line, comprising heating steel billets (slabs) and their multi-pass alternating compression in thickness and width in horizontal and vertical rolls of the roughing stand group, and subsequent multi-pass compression to a final thickness in a continuous finishing group of stands with tension, and the reduction in width is completed when the ratio of strip thickness to width is reduced to a value of at least 0.015, and proc Weaving in the finishing group is carried out with regulated specific tension and compression for the passage of not more than 50% [3].

The disadvantage of this method is that when the strip is rolled in a continuous finishing group of stands, an uncontrolled change in its width occurs due to the broadening of its edges and drags from the action of tension between the stands. This reduces the accuracy of the strips in width, and, as a consequence, to increase the side trim and reduce the yield.

The technical problem solved by the invention is to increase the accuracy of the strip widths.

To solve the technical problem in the known method for the production of wide strips, including heating steel billets and their multi-pass reduction in thickness and width, according to the invention, when the ratio of strip thickness to width is not more than 0.20, the strip is bent around a roller whose barrel length does not exceed 0 , 9 from the width of the strip, while simultaneously squeezing it across the width in a bent state, while the angle of coverage of the roller with a strip is at least 10 °.

Figure 1 shows a diagram of the mutual arrangement of the rolled strip, vertical rolls and rollers when implementing the proposed method, front view. In Fig.2 - the same as in Fig.1, a top view. Here 1 is the rolled strip; 2 - supporting rollers; 3 - bending roller; 4 - vertical rolls.

The invention consists in the following. As the thickness and temperature of the rolled strip decreases during its rolling, its stability in the transverse direction decreases. Therefore, when the ratio of the thickness H of the strip to its width B is not more than 0.20, the force action on its edges from the side of the vertical rolls will lead not to compression in width, but to bending with the formation of a warp. For this reason, in the known method [3], the possibility of crimping the strip across the width transported in a flat state is limited by the ratio: N / B≥0.15. The need to fulfill this condition does not allow to squeeze in width (calibrate) a thin strip in the finishing group of stands.

The bending of the strip 1 between the supporting rollers 2 with the help of the bending roller 3 leads to the fact that in the bending zone the resistance of the strip against loss of shape (warping) from the action of transverse forces increases depending on the angle φ of the coverage of the roller 3 by strip 1 (figure 1), 2-5 times. Due to this, under the action of the vertical rolls 4, the strip 1 is squeezed in width without the formation of warping.

It was experimentally established that if the ratio of the thickness H of the strip 1 to its width B is more than 0.20 (N / B> 0.20), then the strip can be crimped in width without bending around the roller 3. In the case when B / H≤0 , 20, to prevent loss of stability during compression over the width, bending of the strip 1 around the bending roller 3 is necessary.

It was also experimentally established that when the angle of coverage of the bending roller 3 by strip 1 is less than 10 °, strip 1 cannot be deformed in width (calibrated) due to its loss of stability.

When the length of the barrel L of the bending roller 3 is more than 0.9 of the width B of the strip 1 (Fig. 2), the compression range in width is not sufficient to eliminate the width, since the movement of the vertical rolls 4 towards each other will be limited by the length L of the barrel of the bending roller 3.

Method implementation examples

In the penultimate interstage gap of the finishing group of stands of the continuous broadband mill 2000, a pair of supporting rollers 2 and a bending roller 3 with a mechanism for moving it in a vertical plane are installed in the bearings. The barrel length of the bending roller 3 is: L = 1360 mm. A pair of cantilever vertical drive rolls 4 is installed in the same inter-stand space.

A steel billet (slab) with a width of 1600 mm from 09G2S strip steel is heated to a temperature of 1280 ° C and rolled in a roughing stand group with alternating reductions in thickness and width in horizontal and vertical rolls into a strip with an intermediate thickness of 50 mm and a width of B = 1610 mm .

Then the strip is tucked into rolls and squeezed in a continuous finishing seven-group quarto group. The thickness of the strip in the penultimate interstage gap is H = 9.2 mm; therefore, the ratio H / B = 9.2 / 1610 = 0.0057 <0.2.

After refueling the strip 1, the bending roller 3 is lowered down to the position shown in FIG. Under the action of the bending roller 3, the strip 1 bends between the supporting rollers 2, which covers the bending roller 3 circumferentially at an angle φ = 20 °> 10 °.

Since the barrel length of the bending roller is L = 1360 mm, then L = 1360 mm <0.9 · B = 1610 · 0.9 = 1449 mm. The edges of the curved strip 1 go beyond the dimensions of the length of the barrel L of the bending roller 3.

Using push mechanisms, the absolute compression of strip 1 across the width of the vertical rolls 4 is set to DV = 10 mm, and the strip 1 is rolled to a final thickness of H ₁ = 8 mm with simultaneous compression of its edges by vertical rolls 4 that calibrate the strip 1 to the width 1600 mm, eliminating its wide range. The strip in a bent state when compressed by vertical rolls does not lose stability.

The rolled strip is cooled with water on a discharge roller table and wound into a roll. Due to the calibrating compression of the strip edges, its width 5 does not exceed ± 1.0 mm.

The finished strip is subjected to dressing and processing on the slitting unit. The yield after cutting is Q = 99.8%.

Variants of the method for the production of wide strips and indicators of their effectiveness are given in the table.

From the data presented in the table, it follows that when implementing the proposed method (options No. 2-4), an increase in the accuracy of the hot rolled strips in width is achieved.

Table Modes of production of hot rolled strips and their effectiveness No. p / p N / A L / B F deg. δ, MM Q% one 0.05 0.8 8 ± 5 97.4 2 0.10 0.7 10 ± 1 99.7 3 0.15 0.9 twenty ± 1 99.8 four 0.20 06 thirty ± 1 99.8 5 0.30 1,0 40 ± 7 97.1

Due to this, the amount of side trim is reduced, the yield is maximum. In cases of transcendental values of the declared parameters (options No. 1 and No. 5), the width of the hot-rolled strips increases, which leads to a decrease in the yield.

The technical and economic advantages of the proposed method are that the bending of a steel strip during hot rolling, having a thickness to width ratio of not more than 0.2 around the roller, the barrel length of which does not exceed 0.9 of the strip width, does not have an angle of coverage of the roller with the strip less than 10 °, ensures the stability of the strip when it is compressed in width. Due to this, calibration of the strip width in the finishing group of the continuous broadband mill is achieved, increasing the accuracy of the strip widths, reducing the consumption coefficient and increasing the yield.

As the base object, the closest analogue was adopted [3]. Using the proposed method will increase the profitability of the production of wide steel hot-rolled strips by an average of 2-3%.

Information sources

1. Patent of the Russian Federation No. 2274504, IPC B21B 1/22, 2006;

2. Patent of the Russian Federation No. 2414972, IPC B21B 1/22, 2011;

3. Patent of the Russian Federation No. 2273535, IPC B21B 1/22, 2006

Claims (1)

A method for the production of wide strips, including heating steel billets and multipass reduction in thickness and width in horizontal and vertical rolls of a broadband mill, characterized in that when the ratio of strip thickness to width is not more than 0.20, the strip is bent around a roller whose barrel length is not exceeds 0.9 of the strip width, while simultaneously squeezing it across the width in a bent state, while the angle of coverage of the roller with a strip is at least 10 °.

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