Andritz-patentverwaltungs-gesellschaft M.b.h.

Maschinenfabrik Andritz Actiengesellschaft

Maschinenfabrik Andritz Actiengesellschft

Erich Mahr

Wilhelm Hofkirchner

Gerald Maresch

Jovan Starcevic

The invention concerns a process for pickling material strips made of steel, in particular stainless steel, where the strip passes through at last one pickling bath with at least one pickling acid. It is above all characterized by the fact that the acid concentration and/or the acid composition is controlled as a function of the material quality, of the pre-treatment and of the operating parameters of the pickling plant. Furthermore, the invention concerns a plant for carrying out the process, where at least two circulation tanks having different acid concentrations and/or acid compositions are provided.

Process and plant for pickling materials made of steel, in particular

In a process and plant for pickling steel strip, a highly refined steel strip is delivered in the form of a coil, uncoiled by an uncoiling hasp 1 and advanced through at least one predescaling plant 3, pickling sections and a rinsing plant 7 to a recoiling hasp 9 or a transverse cutting plant. The strip is clamped to the recoiling hasp 9 ,--,--; recoiled and drawn solely thereby or in conjunction with other driven treatment rolls through the treatment plant or is cut into sheets by the transverse cutting plant. The plant comprises at least one elongated, preferably shallow pickling vat having a supporting structure of steel, glass fibre reinforced synthetic resin or polypropylene and a lining of acid and abrasion resistant material including PVC, carbon bricks, graphite filled and/or aluminium oxide filled polyester resin.

Process and plant for pickling stainless steel strip

Process for pickling high-grade steel, preferably high-grade steel hot strip, the high-grade steel being subjected to pickling with neutral electrolyte as well as to an after-treatment with mixed acid, nitric acid or a mixture of iron fluoride and hydrofluoric acid, the pickling with neutral electrolyte being preceded by a pre-treatment with sulfuric acid.

Pickling high-grade steel

Process and apparatus for the continuous electrolytic treatment and/or coating of a moving metallic strip while changing the spacing between the strip and at least one electrode as a function of deviations (distortions) of the strip normal to the direction of movement of the strip in order to automatically maintain an optimal spacing so as to keep the voltage drop in the electrolyte low and save energy. For that purpose feeler means are provided to determine the deviation and generate a first signal. A second signal is generated as a function of the velocity of the strip. The period from the moment of detecting the deviation to the moment of its arrival at the electrode, reduced by the response period for changing the spacing, is computed. The period needed for passing through the electrode is computed. The first signal is broadened at its maximum value in terms of time as a function of the length of the electrode(s) and of the second signal, and the spacing between the strip and the electrode is adjusted at the correct time and for the period of passage of the deviating portion of the strip as a function of the determined and computed data.

Process and apparatus for the continuous electrolytic treatment and/or

Process and apparatus for the continuous electrolytic treatment and/or coating of a moving metallic strip whilst changing the spacing between the strip and at least one electrode as a function of deviations (distortions) of the strip normal to the direction of movement of the strip in order to automatically maintain an optimal spacing so as to keep the voltage drop in the electrolyte low and save energy. For that purpose feeler means are provided to determine the deviation and generate a first signal. A second signal is generated as a function of the velocity of the strip. The period from the moment of detecting the deviation to the moment of its arrival at the electrode, reduced by the response period for changing the spacing, is computed. The period needed for passing through the electrode is computed. The first signal is broadened at its maximum value in terms of time as a function of the length of the electrode(s) and of the second signal, and the spacing between the strip and the electrode is adjusted at the correct time and for the period of passage of the deviating portion of the strip as a function of the determined and computed data.

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Purkersdorf, Austria

Erich Mahr