Metal founding – Process – With measuring – testing – inspecting – or condition determination
Reexamination Certificate
1999-06-30
2001-07-17
Pyon, Harold (Department: 1722)
Metal founding
Process
With measuring, testing, inspecting, or condition determination
C164S484000
Reexamination Certificate
active
06260604
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a strand pulling-off method for a metal strand, particularly a steel strip, cast in a curved continuous casting plant, wherein the metal strand is initially vertically pulled from a casting mold, wherein a curved shape is then imparted on the metal strand in a curved entry driver driven with an entry torque, and wherein, after reaching a horizontal strand travel direction, the metal strand is finally straightened in a curved exit driver driven with an exit torque.
2. Description of the Related Art
Strand pulling-off methods of the above-described type are generally known in the art. In these methods, the cast metal strand is bent by means of a driven curved entry driver, also called bending driver, from the vertical into a curved shape. After reaching the horizontal, the metal strand is then once again straightened by means of a driven curved exit driver, also called straightening driver, so that the metal strand leaves the curved continuous casting plant in a horizontal strand travel direction.
In the optimum situation, the strand substantially has the shape of a circular arc between the curved entry driver and the curved exit driver. However, even slight differences in the speeds between the drivers have the result that the metal strand is deflected from its ideal line. The metal strand then either extends in the shape of a chord or the metal strand sags through. Accordingly, the speed differences may lead to difficulties in operating the plant or may even lead to interruptions of the casting operation. In either case, the quality of the cast metal strand is negatively influenced.
The book “StranggieBen von Stahl—Einführung und Grundlagen” [Continuous Casting of Steel—Introduction and Basics] by Hans Schrewe, Verlag Stahleisen mbH, Düsseldorf (Germany) 1987, pages 13 and 46 to 50, discloses a strand pulling-off method for a metal strand, particularly a steel strip, cast in a curved continuous casting plant, wherein the metal strand is initially vertically pulled from a continuous casting mold, a curved shape is then imparted on the metal strand in a curved entry driver, the metal strand is then guided in a multiple-roller drive and the metal strand is straightened in several steps, so that the metal strand leaves the curved continuous casting plant after reaching a horizontal strand travel direction.
SUMMARY OF THE INVENTION
Therefore, it is the primary object of the present invention to provide a strand pulling-off method in which a deviation of the cast metal strand from its ideal line is prevented as much as possible.
In accordance with the present invention, an entry speed is assigned to the curved entry driver and an exit speed is assigned to the curved exit driver, the entry torque and the exit torque are determined, and the exit speed is adjusted in such a way that the entry torque as well as the exit torque have a positive value.
In accordance with a preferred feature, the exit speed is lowered when the quotient of exit torque to entry torque exceeds a desired quotient value, and the exit speed is conversely increased when the quotient of exit torque to entry torque drops below the desired quotient value. This ensures that the metal strand follows the ideal line even better.
In accordance with another preferred feature, the desired quotient value is increased when after lowering the exit speed the sum of exit torque and entry torque increases and the desired quotient value is conversely lowered when after an increase of the exit speed the sum of exit torque and entry torque increases. This feature makes it possible that the curved continuous casting plant automatically adjusts an optimum strand shape. Simultaneously, the plant is operated with minimum energy requirements.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of the disclosure. For a better understanding of the invention, its operating advantages, specific objects attained by its use, reference should be had to the drawing and descriptive matter in which there are illustrated and described preferred embodiments of the invention.
REFERENCES:
patent: 6044895 (2000-04-01), Kuttner et al.
Bernhardt Jurgen
Hoen Karl
Lippold Carsten
Parschat Lothar
Del Sole Joseph S
Kueffner Friedrich
Pyon Harold
SMS Schloemann--Siemag Aktiengesellschaft
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