RU2279326C2 - Sheet rolling stand rolling roll - Google Patents

Abstract

FIELD: rolling rolls for stands of continuous strip rolling mills.

SUBSTANCE: roll has curvilinear profile of generatrix of roll barrel and annular turnings along length of roll barrel. According to invention cylindrical surface of said turnings has profile equidistant relative to profile of roll barrel. Depth of turnings consists at least 0.25 of absolute reduction value in stand for predetermined deformation mode. Surface of roll has different micro-geometry along length of roll barrel. Height of micro-irregularities of cylindrical surface of turnings consists of 0.1 - 0.3 of micro-irregularity values of roll barrel surface.

EFFECT: enhanced efficiency of rolling mill, lowered metal consumption, improved stability of strip along roll barrel relative to rolling axis at discharging end portions of strips.

3 cl, 3 dwg, 1 tbl

Description

The invention relates to rolling production, in particular to a tool for continuous rolling mills, mainly for cold rolling strips, and can be used in all mill stands except for finishing.

Known work roll sheet rolling stands, the ends of the barrels of which are made in the form of an inverse cone in order to ensure lateral stability of hire (AS USSR No. 398298, M. class. In 21 In 27/02, 1972).

Also known is a roll of a sheet rolling stand with a barrel forming in the form of separate sections of wavy curves connected by sections of a smooth barrel (USSR AS No. 293646, M. class. 21 V 27/02, 1969).

The disadvantages of these rolls include the difficulty of their use in cold rolling mills, since the specified profile of their barrels does not provide equal strip width, especially when rolling narrow strips, and also reduces the stability of the latter from lateral displacements.

Known work roll sheet rolling stand with a profile forming a barrel, made with concavity according to the hyperbolic law with a ratio of half the real axis of the hyperbola to the value of the maximum concavity of the generatrix, equal to 0.1-0.3 (AS USSR No. 1158262, M. Cl. 21 B 27/02, 1983).

However, the possibility of its widespread use is limited by the concave profiling of the barrel, since work rolls with the initial convex profile of the forming barrel are used to compensate for their deflection on the stands of continuous strip mills of cold rolling. In addition, when rolling the rear end of the strip with a large longitudinal and transverse thickness variation of the tackle, with a lower tension value and with a large uneven contact stress along the roll barrel, it is not possible to keep the strip from lateral displacement with known curved profiles of the barrel forming.

The closest in technical essence and the achieved result to the claimed roll is a horizontal roll containing a barrel with a number of box calibers, in which, in order to increase the stability of the strip during rolling, the release of the caliber facing the rolling axis is made in the form of two mating surfaces. This roll is used for rolling wide strips in the rough stands of hot rolling mills 2000.

The disadvantage of the roll is that during cold rolling the absolute reduction (Δh) in the stands will be 0.1-0.9 mm, which means that the depth of the metal flowing into the caliber will be comparable to the compression in the stand. Thus, with such a small depth of gauge and metal contact with the outlets of this configuration on cold rolling mills, it will not provide the efficiency of using a roll to ensure lateral stability of the strip in the stand.

The purpose of the invention is to reduce metal consumption and increase mill productivity by increasing the lateral stability of the strip in the stands of continuous strip mills.

This goal is achieved by the fact that on the working roll of a sheet rolling stand of a rolling mill with a curved profile of the forming barrel and surface microgeometry according to the invention, annular grooves are made along the length of the barrel, the cylindrical surface of which has a profile that is equidistant to the profile of the roll barrel.

In a preferred embodiment, the roll is made with grooves with a depth of at least 0.25 of the absolute compression in the stand for a given deformation mode.

In addition, the height of the microroughness of the cylindrical surface of the grooves is made equal to 0.1-0.3 the height of the microroughness of the surface of the roll barrel.

The stability of the strip against displacement along the roll is ensured by the fact that the side surfaces of the grooves are perpendicular to the side flow of metal in the rolls and rigidly fix the strip along the axis of rolling.

The change in average normal contact stresses along the length of the roll barrel is significantly affected by the coefficient of external friction, which in turn depends on changes in the microroughness of the surface of the roll barrel. So, according to A.P. Grudev (Grudev A.P. External friction during rolling. M., Metallurgy, 1973) with a decrease in the roughness height from Ra≈5.5 μm to Ra≈1.0 μm (Ra is the roughness parameter according to GOST 2783-73) the friction coefficient is reduced by about half. This in turn leads to a decrease in the average normal contact voltage (P _cf ). Thus, two factors will influence the distribution of P _cf along the length of the roll barrel: uneven compression of the strip due to the depth of the annular grooves and uneven roughness of the grooves and barrels. The sum of these two factors leads to the appearance of an additional relief on the surface of the roll barrel, preventing the strip from moving along the roll.

In the conditions of a cold rolling workshop, rolls are profiled on a folding grinder. Curved profiling is performed using a special copier connected to the grinding wheel mechanism. First, grind the specified profile of the barrel 1 (convex cylindrical, concave) (Figs. 1, 2, 3), and then perform annular grooves 2, deepening the grinding wheel to a predetermined depth, grinding the cylindrical surface of the groove in the same copier shape as the surface of the barrel roll.

After grinding, the surface of the barrel and grooves is Ra = 0.8-1.3 microns. To obtain micro-roughness on the surface of the barrel equal to Ra = 5.5-7.0 μm, the roll is subjected to bead-blasting. To do this, before processing on the surface of the barrel impose a stencil with slots along the barrel with a width equal to the width of the sections with the required maximum height of microroughnesses. After bead-blasting, the surfaces covered with a stencil (grooves) will remain polished with a roughness of 0.8-1.3 μm Ra, and in unprotected areas they will receive a high roughness in the range of 5.5-7.0 μm Ra. If we take the extreme values of roughnesses of grooves and roll barrels, we obtain a ratio of roughnesses of grooves equal to 0.1-0.3 of the roughness of the surface of the barrel, which provides an additional effect of strip stability during rolling.

The performance of the roll kit was tested on a laboratory mill with a roll diameter of D = 120 mm and a barrel length of L = 150 mm. We used rolls with barrel roughness Ra≈5.8 μm with a polished surface of the grooves (Ra = 1.0 μm) and a depth of δ = 0.1; 0.2; 0.3; 0.4; 0.5 mm Stripes were rolled from aluminum with a thickness of H = 3.5 mm, a width of B = 80 cm and a length of L = 400 mm. Emulsol T was used as a lubricant. Strip instability was created by skewing the rolls in a vertical plane (δh). The strips were rolled with compression Δh≈1.0 mm. Instability (K) was estimated by the value of the edge displacement at the exit of the rear end of the strip relative to its front end. K = Y / B; where Y is the offset value of the trailing edge; B is the bandwidth. The table shows the experimental data in the study of the stability of the bands.

Experience No. Surface relief δ, mm δh, mm Y mm TO one Barrels polished with a cylindrical profile Ra _in ≈0.8 μm - 0 0 0 2 also - 0.19 31 0.388 3 also - 0.3 42 0.525 four Barrels notched with a cylindrical profile Ra≈5.8 μm - 0 0 0 5 also - 0.2 24 0.3 6 also - 0.31 35 0.437 7 Notched Ra≈0.8 μm with a polished surface of the grooves Ra _p ≈0.8 μm 0.1 0.2 7 0,088 8 0.3 13 0.163 9 also 0.2 0.21 3 0,038 10 0.30 8 0.1 eleven also

0.3 0.19 0 0.8 12 0.29 2 0,025 13 also

0.4 0.19 0 0 fourteen 0.30 0 0 fifteen also

0.5 0.20 0 0 16 0.31 0 0 17 Grinded (Ra≈0.8 μm) with a polished surface of the grooves (Ra _p ≈0.8 μm)

0.1 0.19 12 0.15 eighteen 0.29 19 0.237 19 also 0.2 0.21 5 0,062 twenty 0.30 eleven 0.137 21 also

0.3 0.20 2 0,025 22 0.31 5 0,062 23 also

0.4 0.2 0 0 24 0.3 0 0 25 also

0.5 0.21 0 0 26 0.32 0 0

As follows from the table, when rolling in polished and notched rolls with a cylindrical profile of the barrel when the rolls are skewed by δh = 0.20 mm (experiment 2, 5), the rear end of the strip shifts by 31 mm (K = 0.388) and 24 mm, respectively (K = 0.3). With an increase in δh to 0.30 mm (experiment 3, 6), the displacement increases on both polished and notched rolls, which indicates insufficient strip stability. When rolling in notched rolls with polished grooves, the strip retains its stability even at δh = 0.20 mm and the depth of the depressions δ = 0.30 mm and more (experiment 11, 12).

When rolling on the same rolls, but with the same surface roughness of the barrel and annular grooves, stability is achieved with a depression depth of δ = 0.40 mm or more (experiment 23-26).

Thus, the use of rolls with the declared surface topography on industrial cold rolling mills stabilizes the process and ensures the release of the rear end of the strip without stopping and reducing the rolling speed, which will reduce metal consumption by 5-8% and increase mill productivity by 10-15%.

Claims (3)

1. A work roll of a sheet rolling stand with a curved barrel forming and surface microgeometry, characterized in that annular grooves are made along the roll barrel, the cylindrical surface of which has a profile that is equidistant to the roll barrel profile. 2. The roll according to claim 1, characterized in that the grooves are made with a depth of not less than 0.25 of the absolute compression in the stand for a given deformation mode. 3. The roll according to claim 1 or 2, characterized in that the height of the microroughness of the cylindrical surface of the grooves is made equal to 0.1-0.3 the height of the microroughness of the surface of the roll barrel.

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