SU1678468A1 - Ingot rolling method - Google Patents

Abstract

The invention relates to rolling production and can be used in the rolling of ingots on sizing mills. The aim of the invention is to increase the yield by reducing the metal to the cut. The method consists in cooling the bottom part of the ingot after removing its taper in the first pass, followed by rolling and cooling the end parts of the roll after each of the passes for which the ratio d / Hcp 0.5 is valid, where d is the length of the arc , Нср - average strip height. The method allows to improve the conditions of metal capture by rolls, to increase the yield by 1%. 1 tab.

Description

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The invention relates to rolling production and can be used in the rolling of ingots on sizing mills.

The purpose of the invention is to increase the yield by reducing the metal to the cut.

The method consists in cooling the broadened part of the ingot after removing its taper in the first pass, followed by rolling and cooling the end parts of the roll before each of the passes, for which the ratio d / NSD: 0.5 is valid, where 1Д is the length arc capture, NSR-average height of the strip.

When rolling high strips with a ratio of the length of the gripping arc to the average height of the strip 1d / Ncr 0.5, the largest increase in weft occurs at the ends of the roll. In this case, the metal layers adjacent to the surface of the roll, get a large stretch compared with the central layers. This results in blooms with irregular geometrical shape of their ends, characterized by the presence of a tail. If forced cooling (according to the proposed method) of the end sections of the roll is carried out, this will lead to an increase in the resistance to deformation and, consequently, to a decrease in the plastic flow of the metal in the layers adjacent to the surface. At the same time, the central layers in this case are deformed more intensively and the total deformation of the end parts of the roll goes more evenly. The trimming of the ends will decrease.

When rolling in d / hcp 0.5 aisles, the growth of the weft stops and its reduction begins. This indicates that the deformation of the end sections proceeds more evenly. Therefore, produce refrigeratedON XI 00 ON 00

In this case, the end sections of the rolled strip are inexpedient.

The method is carried out as follows.

After the ingot is removed from the heating well, it is fed to the receiving roller table of the blooming mill with the wider part forward, where forced cooling is performed, using nozzles, of the ingot head (narrow end). Then the ingot is rolled in the working stand of the mill and before the rolling in the second pass the end sections of the roll are cooled. Thus, the strip is cooled after all passes for which the ratio 1d / HCP S 0.5 is valid.

Example. Boiling steel ingot weighing 8 tons with dimensions of 725x665 mm (head of the ingot), the lower section of 790x720 mm (bottom part of the ingot) is cast in a mold, broadened downwards. After the heating in the heating wells, the ingot is fed by the broad part forward to the receiving roller table of the blooming working stand, equipped on both sides with nozzles for cooling the end parts of the roll. Rolling is carried out in 11 passes into a bloom with a section of 320 x 275 mm according to the 4x4x2x1 scheme.

Before the task of the ingot, the surface of the ingot head (narrow end) is cooled to 300 ° C. The front (broad end) is not cooled. Then the ingot is rolled with a reduction corresponding to the absolute taper of the ingot DN 790-725 65 mm. Before rolling in the second pass, the head and bottom parts of the roll are cooled to a temperature difference in these parts on the surface and in the center of at least 300 ° C. AT

Further, to determine the feasibility of cooling the end parts of the roll during the rolling, the d / Hcp parameter is determined by passages.

The obtained ratios of the length of the gripping arc to the average height of the strip indicate that, in order to reduce the non-uniformity of deformation and, consequently, decrease the weighting of the end parts of the roll, its ends should be cooled after the first 7 passes.

The method provides an increase in the yield by reducing the technological waste of the metal to the cut by 0.5-1.0%.

Claims (1)

Invention Formula The method of rolling ingots, which includes heating, transporting, cooling the head part of the ingot, removing the taper and rolling, characterized in that, in order to increase the yield by reducing the metal to the cut, after removing the taper, the bottom part of the ingot is cooled and the rolling is carried out with end cooling parts of the roll in front of each of the passes upon reaching the ratio 1d / Nsr 0,5 Where is the length of the arc of capture, NSR - the average height of the rental.