Method and plant for producing flat rolled products

Abstract

The invention concerns a method and a plant for producing flat rolled products, in order to obtain strips having a multiple crown transverse profile that subsequently have to be divided in a longitudinal direction into strips of a smaller width; the method provides a rolling step carried out in a rolling mill comprising roughing stands and finishing stands equipped with respective work rolls, in order to supply a strip of a determinate width.

Description

FIELD OF THE INVENTION[0001]The present invention concerns a method for producing flat rolled products, such as strip, and the corresponding production plant. In particular, the invention concerns a method and a plant for obtaining strip having a final transverse profile with multiple crown and with optimal geometric characteristics in terms of profile and planarity of the strip, even in the case where the strip is subsequently divided into longitudinal portions.[0002]The present invention can be applied in rolling processes both hot and cold, for producing strips in any type of ferrous or non-ferrous materials.BACKGROUND OF THE INVENTION[0003]Rolling plants are known, which comprise a multi-stand rolling mill, normally divided into first roughing stands and second finishing stands. A temperature restoration system may be present between the roughing and finishing stands.[0004]The rolling mill may or may not be disposed in line with a continuous casting machine that produces thin sl...

AI Technical Summary

Benefits of technology

The present invention allows for the production of various double, triple and quadruple crown profiles in a rolling process. By controlling the cooling of the work rolls, the thermal crown can be optimized to enhance the profile control capacity on the divided portions of the strip. The invention enables a greater flexibility in the cooling efficiency along the width of the strip, which allows for the optimal thermal crown to be defined during the double or multiple crown rolling campaign.

Problems solved by technology

However, in order to meet market requirements, there is often the need to produce coils with a narrower width than the barrel of the rolling rolls, with a consequent reduction in the productivity of the plant.

The first disadvantage concerns the crown of the two half-strips.

It is very important to create an accurate profile during hot rolling since this profile cannot be modified in downstream processes, since any possible modifications would cause defects in planarity, as well as difficulties in carrying out the subsequent steps of the production cycle.

This asymmetrical profile, however, is not very suitable for subsequent processing said half-strips, making their downstream treatment unstable, with possible drift and difficulties in winding.

Furthermore, in JP'405 it is problematic to carry out the longitudinal cut in an inter-stand space, and even more problematic to control the two half-strips, especially when dealing with thin thicknesses, due to the high speeds involved.

The solution of JP'405 does not in practice allow to control the crown of the two half-strips since, in the single rolling stand, the profile of the half-strips is returned almost symmetrical simply by Hertzian pressure at the edges.

It can therefore be understood that in the event that the rolled strip must subsequently be divided longitudinally into two half-strips before, or during, or even after winding, in the state of the art solutions are not available for a precise control of the crown.

With regard to the crown, it must also be considered that the heating of the rolling rolls is one of the basic problems to be faced in both hot and cold rolling.

These problems, already considerable in the case of hot rolling with conventional processes, are even more exasperated for endless production processes, in which rolling on the strip finishing mill can last up to 10 hours without interruption, compared to 2-3 minutes of the conventional coil-to-coil process.

This phenomenon creates disturbances on the control of the profile and planarity of the strip being rolled:

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