RU2397034C1 - Tool of continuous wide strip hot rolling mill - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: tool comprises working rolls with barrels installed in certain stand of mill, at the same time each barrel is arranged with curvilinear generatrix of its surface and has minimum diametre in the middle of its length, value of which depends on profile of rolled strip. Provision of required section of strips with optimal difference of thicknesses in the middle and at the edges of strip is delivered as a result of the fact that in order to roll strips of double width of its requied value, difference δ of maximum and minimum diametres of roller barrels in i stand of finishing group of mill is controlled by mathematical expression, which takes into account similar difference Δ of roller diametres of the same stand for rolling of strips of single width and parametres of strips cross section.

EFFECT: invention is intended to improved geometry of cross section of double-width hot-rolled strips intended for further slitting, due to appropriate profiling of working rolls in finishing stands of continuous wide-strip mill.

1 dwg, 1 ex, 1 tbl

Description

The invention relates to a tool for metal forming and can be used for hot rolling of sheet steel on continuous broadband mills (NSHPS).

The main tool of such mills is work rolls installed in quarto stands (i.e. four-roll, with two backup and two work rolls). Usually NSHPS contain two groups of stands: roughing and finishing. Barrels of NSHPS work rolls are made with appropriate profiling, depending on the specific range of rolled strips. Features of rolls of hot-rolled sheet mills are described, for example, in the book by A. I. Tselikov et al. Machines and Units of Metallurgical Plants. M .: "Metallurgy", 1988, p.196-198.

A roll roll of a broadband mill stand is known, the barrel forming which includes a working section with a parabolic surface and conical surfaces adjacent to it on both sides, and the transition of the parabolic surface to the conical is made at a predetermined distance from the edges of the roll barrel (see AS USSR No. 1014604 , CL B21B 27/02, published in BI No. 16, 1983). However, such a roll is not suitable for hot rolling of strips of double width, which are spread during subsequent longitudinal cutting into two strips of single width.

The closest analogue to the claimed object is the tool (work rolls) of the finishing group of the hot rolling mill 1700, given in the book by S. P. Efimenko and V. P. Slednev “Roller of sheet rolling mills”. M .: "Metallurgy", 1980, p.124-125 and the table.

This tool contains work rolls with barrels installed in a specific mill stand, and each barrel is made with a curved surface forming it, having a minimum or maximum diameter in the middle of its length (i.e., the barrel surface is either concave or convex), the value of which depends from the profile of the rolled strip and is characterized by the fact that in the first two stands of the finishing group the barrels of both rolls are concave (see the new profiling method in the table), and in the last two stands the barrels of the upper rolls are convex and the lower x - cylindrical. Such rolls are also not suitable for rolling strips of double width.

Work roll profiling Stand number 7 8 9 10 eleven 12 13 N mm 30,0 18.05 10.90 6.10 4.35 3.40 2.65 h _i mm 18.05 10.90 6.10 4.35 3.40 2.65 2,30 δ (top / bottom), mm

Δ (mm per pair) +0.40 +0.35 +0.30 +0.25 +0.25 +0.20 +0.15

The technical task of the present invention is to obtain the desired geometry of the cross section of the hot-rolled strips of double width, intended for subsequent longitudinal dissolution, due to the corresponding profiling of the work rolls of the stands of the finishing group NSHPS.

To solve this problem, the NSHPS tool contains work rolls with barrels installed in a specific mill stand, each barrel made with a curved surface forming it and has a minimum diameter in the middle of its length, the value of which depends on the profile of the rolled strip, and for rolling strips double of the width from the required value, the difference δ of the maximum and minimum diameters of the barrels in the i-th stand of the finishing group of the mill is set depending on the similar difference Δ of the diameters of the rolls of the same glue and for rolling strips and single-width depending on the parameters of the cross-section strips of expression

, мм,

mm

where Δh ₁ and Δh ₂ are the values of the transverse different thickness of the finished strips, respectively, of single and double widths, mm;

H and h are the thickness respectively of the roll before the first stand of the finishing group of stands and the final thickness of the strip, mm;

h _i - the thickness of the strip of double width at the exit of the i-th mill stand, mm;

e is the basis of natural logarithms.

It is understood that the thickness of the strips H, h and h _i is measured as usual at their edges.

The above mathematical expression is obtained by processing the experimental data and is empirical.

The essence of the proposed technical solution is to create such roll profiling when rolling double-width strips on NSHPS, which, firstly, provides good lateral stability of the roll in the stands of the finishing group of the mill and, secondly, provides such a cross-sectional shape of strips of single width ( obtained by longitudinal dissolution of wider strips), which is required during their subsequent cold rolling.

The inventive tool NSHPS schematically shown in the drawing.

The upper 1 and lower 2 work rolls contain trunnions 3, placed in the supports (pillows) of the quarto stand (not shown), and barrels 4, the forming of which are concave curvilinear. The maximum diameters D of the barrels are at their ends, the minimum d are in the middle of the length L of the barrels (along the yy axis); the diameter difference D-d = δ or Δ (they can be different for the upper and lower rolls) depending on the width of the rolled strips (double or single). This difference is determined from the above expression.

When hot strips pass through such rolls, the cross-section of the rolled product is convex (lenticular) with the optimal (for solving the problem) difference in thicknesses in the middle and edges of the strips, which was confirmed by experiments.

An experimental verification of the proposed technical solution was carried out at the NShPS 2000 of OJSC Magnitogorsk Iron and Steel Works. For this purpose, when rolling sheet steel of double width intended for longitudinal dissolution into two strips, the values of δ were varied for different values of Δ, Δh _i , Δh ₂ , H, h and h _i for each stand of the finishing group of this mill. The experimental results were evaluated by the quality of the geometry of the strips after their longitudinal dissolution, as well as by the quality of the cold-rolled strips obtained from them.

The best results (yield of rolled products with the required geometry within 98.8 ... 99.6%) were obtained using the proposed tool. Deviations from the recommended values of δ worsened the achieved indicators.

So, when δ is less than calculated according to the proposed dependence, the lateral stability on the cold rolling mill was violated, which in some cases led to their rejection according to the geometry of the cross section. At δ values greater than the calculated ones, the transverse thickness difference of both hot-rolled and cold-rolled strips increased, which caused them to be sorted as not meeting the requirements of the standard. The yield of rolled products with the required geometry in both cases did not exceed 89.5%.

The tool selected as the closest analogue (see above) was not used in the experiments due to its obviously unsuitable for hot rolling strips of double width.

Thus, an experimental verification confirmed the acceptability of the technical solution found to achieve the goal and its advantage over a known object.

The feasibility study showed that the use of the present invention on NSHPS, similar to mill 2000 of OJSC MMK, will reduce production costs for the production of, for example, tackle for tin with a width of 760 ... 780 mm and a thickness of 2.3 mm by no less than 15 % (taking into account the reduction in the value of the edge trim on the strips obtained by longitudinal dissolution) and obtain direct metal savings.

Concrete example

At the NSHPS hot rolling 2000, a rolled strip with a width of 1620 mm and a thickness of 2.3 mm is intended for longitudinal dissolution with the receipt of a rolling for tin.

Work rolls of a YII (first finishing) mill stand for rolling strips of 800 mm wide of the same thickness are performed with concave barrels, and the value D-d = Δ for the upper roll is -0.7 mm, and for the lower -0.6 mm.

Strip parameters: Δh _i = 0.049 mm, Δh ₂ = 0.027 mm, H = 30 mm, h = 2.3 mm, h _i = 18.05 mm.

The value of D-d = δ for the rolls of this stand:

for the upper roll -

;

;

мм.for the lower roll -

mm

In a similar way, the δ values are determined for the remaining stands of the finishing group of the mill.

Claims (1)

A continuous broadband hot rolling mill comprising work rolls with barrels installed in the mill stands, each barrel having a curved surface forming it and having a minimum diameter in the middle of its length, the value of which depends on the profile of the rolled strips, characterized in that when rolling strips of double width from its required value, the difference δ of the maximum and minimum diameters of the roll barrels in the i-th stand of the mill finishing group is set depending on the difference Δ of the roll diameters the same stand when rolling strips of single width and from the parameters of the cross section of the strips in the expression:

where Δh ₁ and Δh ₂ are the values of the transverse different thickness of the finished strips, respectively, single and double widths, mm;
H and h are the thickness of the roll before the first stand of the finishing group of stands and the final strip thickness, respectively, mm;
h _i - the thickness of the strip of double width at the exit of the i-th mill stand, mm;
e is the basis of natural logarithms.

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