Method and device for the continuous detection of the slag level in electroslag remelting installations with short slidable molds

Abstract

A method and an installation for the continuous checking and regulation of the level of the surface of a slag bath in an ESR installation with short slidable molds. For the continuous measurement of the position of the surface of the slag bath, the method employs a radar beam emitted by a radar measuring probe and directed approximately vertically onto the surface.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]The present application claims priority of AT A807 / 2010, filed May 14, 2010, and incorporates the same by reference.BACKGROUND OF THE INVENTION[0002]In electroslag remelting installations (which are also referred to as “ESR installations”) in short slidable molds, it is necessary to keep the level of the slag line, i.e. the level of the molten metal line, approximately constant with respect to the upper edge of the water-cooled mold, in order to avoid thermal overloading of or damage to the installation. Depending on the type of installation, this is achieved by the fact that, depending on the melting rate of an ingot, the re-melted ingot is either continuously or stepwise withdrawn downwards from a mold installed in a stationary position, or the mold is withdrawn upwards in the case of an ingot assembled on a fixed base plate. In both cases, there is a relative movement between the mold wall and the surface of the ingot, in such a way th...

AI Technical Summary

Benefits of technology

"The invention is a method for continuously checking the level of the slag line in open remelting installations, particularly in closed installations with a protective gas hood. The method uses a radar measuring probe installed on the mold cover or the protective gas hood to measure the slag level and automatically control the ingot withdrawal process. The system can detect abrupt changes in the slag level and trigger alarms or corrective measures. The invention allows for the continuous monitoring of the slag level and ensures stable operation of the remelting process."

Problems solved by technology

In order to be able to meet the increased quality requirements on the remelting products, electroslag remelting installations are today designed virtually exclusively as closed installations with a protective gas hood, so that the possibility of a simple visual check is no longer possible.

Indirect methods for checking the slag line, such as the calculation of the slag line level from the quantity of melted metal of the ingot compared to the withdrawal rate of the cast ingot, are helpful, but they are not sufficient, so that the protective gas hood still has to be raised from time to time in order to be able to carry out an additional visual check.

A drawback with this method according to the prior art is that the protective gas effect is disturbed and the entry of air into the space above the slag is enabled, this being undesirable for reasons of casting quality.

Moreover, it is a drawback that malfunctions giving rise to an abrupt change in the slag level cannot be detected in good time by the aforementioned mode of operation.

In this case, there is a rapid fall of the slag line.

This can however also occur with a malfunction of the controller which keeps the immersion depth of the electrode in the slag bath constant.

In the case of an excessively deep immersion of the electrode, this may lead to an uncontrolled rise in the slag line.

This is not possible with the checking methods currently available.

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