Furnace For Non-ferrous Metals

Abstract

A furnace for non-ferrous metals or alloys is provided with a base supporting the furnace. Under the bottom, but supported by the base are arranged at least one electromagnetic stirrer of multiphase type.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a furnace for non-ferrous metals or alloys.

In furnaces for non-ferrous metals, for example aluminum and aluminum alloys, it it known to use electromagnetic stirrers in the same way as for iron and ferrous alloys. See for example Auslegeschrift 1,211,401 or "Berg-und Huttenmannische Monatshefte," 9th issue, 1961, page 300. However, with furnaces for aluminum or its alloys and the like, there is the problem that the furnace has a relatively flat and wide bottom and sides of such a shape that in section the furnace is substantially box-shaped. The strain on this large bottom is such that in order to reinforce it the bottom must be supported by beams or similar support members. Merely applying stirrers at the sides does not provide sufficient stirring action since, because of the geometrical shape, beams, etc., considerable parts of the melt will not be stirred, Stirrers applied under the bottom do not provide effective stirring since beams and so on take up the space nearest the bottom and stirrers applied outside these hardly have sufficient stirring effect on the melt. Furthermore, this space is usually taken up by other members, such as tapping means, current and cooling water conductors, etc.

STATEMENT OF THE INVENTION

The invention aims at a solution of these and other similar problems and is characterized in that below the bottom of the furnace, supporting this, are arranged one or more flat stirrers of multiphase type, supported by the base of the furnace. In this way, the stirrer itself will supply the necessary support under the bottom of the furnace by means of its iron parts, and the stirrer can in turn rest on the base of the furnace. By positioning the stirrer(s) in this way, the entire melt can be effectively stirred and the desired metallurgical effects achieved in a simple and effective manner.

DESCRIPTION OF THE DRAWINGS

The accompanying drawings show in FIG. 1 a stirrer embedded in ceramic compound, supporting the furnace and in

FIG. 2 another type of stirrer.

FIG. 3 shows a detail from FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows an aluminum furnace of electrode or flame type (or intended for some other non-ferrous metal or alloy) having a flat bottom 11 supported by stirrers 13 embedded in ceramic compound 12. The stirrers are preferably of electromagnetic, multiphase type and fed by a current having a frequency of 0.1 - 10 Hz. The iron core(s) 14 of the stirrer is applied under the coils and the stirrer is in turn supported by the base 15. The stirrer coils 13 are brought close to the bottom of the furnace and this is well supported in spite of its relatively large area. The stirring field will extend sufficiently far into the melt to achieve effective stirring which in the normal way homogenizes the temperature and ingredients, etc. If desired, stirrers may also be applied at the sides of the furnace in order to further improve the stirring effect, but these stirrers do not of course affect the strength of the furnace.

The ceramic compound 12 in which the stirrer is embedded may consist of stamping compound usual for furnaces or of sand or gravel mixed with some suitable plastic material.

FIG. 2 shows another non-ferrous furnace having a stirrer 16 (possibly several stirrers) in which teeth 17 or projections from the iron core 18 have been drawn between the flat stirrer coils 19 to lie in direct contact with the furnace bottom 20 (see FIG. 3 which is a detail from the stirrer according to FIG. 2). The bottom of the furnace consists of normal ceramic compound and a sheet of stainless steel (the other walls are normally of conventional carbon steel). This stirrer 16 is supported by suitable parts of the base of the furnace, as can be seen in FIG. 2.

The forces from the base to the stirrer can be transmitted by means of various beam or support constructions under the assumption that the forces from the furnace which are taken up by the stirrers and their iron parts are in turn taken up by the base.

The invention may be varied in many ways within the scope of the following claims.

Claims

We claim:

1. Furnace for non-ferrous metals or alloys with a base supporting said furnace, below the bottom of the furnace there being arranged at least one flat electromagnetic stirrer of multiphase type comprising coils and an embedding mass surrounding the same, said stirrer supporting the furnace and being supported by the base by the embedding masses of the stirrer.

2. Furnace according to claim 1, characterized in that the magnetic iron part of the stirrer windings is provided with poles shoes or projections between the windings and that these projections support the bottom of the furnace.