US3503598A

US3503598A - Composite metal vessel

Info

Publication number: US3503598A
Application number: US681348A
Authority: US
Inventors: Louis Babel; Andre Girard
Original assignee: SOC METALLURGIQUE IMPHY
Current assignee: METALLURGIQUE D'IMPHY SOC; SOC METALLURGIQUE IMPHY; Imphy SA
Priority date: 1966-11-28
Filing date: 1967-11-08
Publication date: 1970-03-31
Anticipated expiration: 1987-03-31
Also published as: DE1558595B1; BE705553A; CH473632A; GB1165938A; SE309827B; FR1509043A

Description

United States Patent O 3,503,598 COMPOSITE METAL VESSEL Louis Babel, Sanvigny-les-Bois, and Andr Girard, Nevers,

France, assignors to Societe Metallurgique dImphy, Paris, France, a company of France Filed Nov. 8, 1967, Ser. No. 681,348 Claims priority, application France, Nov. 28, 1966,

Int. Cl. C21c 7,/00; H05b 5/02 U.S. Cl. 266--39 4 Claims ABSTRACT OF THE DISCLOSURE The invention relates to ya composite vessel, more particularly a ladle with a refractory cylindrical casing, intended to contain molten metal and subjected to highintensity fields produced by an inductive circuit with very low andl low-frequency altern-ating current.

These fields produce, along the parallel and meridian planes of the casing, induced currents short-circuiting on themselves, causing heating of the casing. This heating eiiect is reduced if the metal constituting the casing is nonmagnetic and the frequency is low.

With currents of very low frequency, for example 2 hz. or less, the liquid metal in the ladle can be stirred. However, since the non-magnetic casing begins to melt before the frequency and intensity in the field magnet are high enough, it is very difficult, if not impossible, to produce in this metal an induced current of sufficient intensity to maintain the bath temperature, or-as is often desirable-to increase this temperature to the value desired for casting, for example Iduring and after degassing.

The object of the invention is to provide a non-magnetic, indeformable casing which has high mechanical resistance, is refractory at high temperatures, is fluid-tight in a vacuum or under pressure, and which can permit passage, without appreciable heating, of high-intensity fields from inductive currents of appropriate frequency.

According to the invention, the vessel is constituted, in the heating zone, by assembling profiled metal elements made of a non-magnetic, refractory alloy, for example an austenitic steel, by means of tenons and mortices on these elements, and these elements are electrically insulated from each other by an insulating, refractory seal constituted by a heat-setting cement injected in a substantially liquid state into the continuous interstices between the assembled metal elements.

According to another feature of the invention, a binder is provided around the heating zone and comprises at least two layers of threads or bands, one layer consisting of threads or bands arranged along the generatrices of the cylindrical casing, and the other layer consisting of threads or bands wound helically around the first layer.

The invention will now 4be described with reference to an embodiment given by way of example and shown in the accompanying drawings.

FIGURE l is a general perspective view lof a vessel constituting a pouring ladle, with parts cut away;

3,503,598 Patented Mar. 3l, 1970 ICC FIGURE 2 shows the bottom of the vessel;

FIGURE 3 is a perspective view of one of the elements constituting the cylindrical casing of the vessel, and

FIGURE 4 is a section on a line IV-IV in FIGURE 1, on a larger scale, showing an insulating seal between two elements in the casing.

The ladle shown in FIGURE 1 has a cylindrical casing or envelope 1 extending over the entire heating height and assembled from profiled elements 1a. The upper end of the ladle has a cylindrical barrel-plate 2, surmounted by a cover 3 with a pipe 4 and carrying trunnions 5 to allow pivoting.

The profiled elements 1a consist of panels such as that shown by way of example in FIGURE 3. This panel has two tenons 1b and two mortices 1c for assembly with the identical adjacent panels.

The bottom 3 of the ladle (FIGURE 2) is made in the same manner by assembling fiat panels 3a.

The elements 1a, 3a are made of a non-magnetic, refractory alloy, such as an austenitic steel, for example by moulding, within narrow tolerances. The dimensions of the tenons and mortices are such that when the elements are assembled according to the principle of the construction play, small interstices-for example of 1 to 2 mm.- can be left between all the faces of mutual contact between vthe elements. These interstices are formed by means of appropriate packing strips of refractory insulating material, e.g. expanded polystyrene.

Before the elements are assembled, they are subjected to controlled oxidation which gives them preliminary insulation.

During assembly of the vessel, the packing strips are put in position at the same time as the profiled elements.

When the casing for the vessel h-as been formed in this manner, refractory cement is injected under pressure until it fills the interstices 1d between the elements 1a (FIG- URE 4). Suitably placed seals 1e prevent premature leakage.

The cement used is a refractory, heat-setting cement of low viscosity. In particular, it may be a slurry composed of a binder based on ethyl silicate, alcohol and refractories of a given grain size distribution, such as sillirnanites, zirconium oxides, etc.

At the ambient temperature a silica gel forms. This has p a drying effect and causes setting to begin. The whole is then grilled, then heated to the final setting temperature of the order of 900 to impart the final resistance to the insulating seals.

The operations mentioned produce a monolithic Vessel with permanently interlocked profiled elements which have high lmechanical resistance and can be subjected to high-intensity fields produced by inductive currents of a sufficiently high frequency for the intended treatment of the metal bath.

To prevent the irregularities which might arise on account of the alternate heating and cooling, the vessel has-according to the invention-a binder in the zone constituted by the assembled elements.

This binder is made with threads or bands, such as glass fibres with high mechanical properties or non-magnetic metal wires or bands insulated fromr each other.

These threads or bands are arranged in at least two layers. The first layer consists of threads or bands 6y arranged along the generatrices of the cylindrical casing 1. To this end hooks or similar means 7` (FIGURE l) are provided on the cylindrical barrel-plate 2 of the vessel, in order to grip the threads or bands, which, under the end 3, are arranged in layers of parallel threads or bands. The second layer consists of threads or `bands 8 wound helically around the first layer.

Each layer is coated with a lacquer or varnish, and finally the assembly is placed in an oven before being taken into service.

What we claim is:

1. A composite Huid-tight refractory metal ladle for the treatment of molten metals comprising a cylindrical envelope surmounted by a cover, a heating zone formed by said envelope, a plurality of permanently interlocked rectangular proled non-magnetic refractory metal alloy elements forming said heating zone, mortices and tenons on the sides of each of said elements locking adjacent ones of said elements together and means for electrically insulating said elements from each other comprising an insulating refractory seal of a heat setting cement lling the interstices between said interlocked elements.

2. A composite fluid-tight refractory metal ladle for the treatment of molten metals comprising a cylindrical envelope, a heating zone formed by said envelope, a plurality of interlocked rectangular profiled non-magnetic refractory metal alloy elements forming said heating zone, mortices and tenons on the sides of each of said elements locking adjacent ones of said elements together and means for electrically insulating said elements from each other comprising an insulating refractory seal of a heat setting cement filling the interstices between said CII interlocked elements including a binder around the heating zone comprising at least two layers of'threads or bands for said binder, one of said layers consisting of threads or bands arranged along the generatrices of the cylindrical casing, and the other of said layers consisting of threads or bands wound helically around said References Cited UNITED STATES PATENTS 2,170,254 8/1939 Seil 266-43 2,266,785 12/1941 McLain 266-43 X 3,396,962. 8/19618 Smith et al 266-43 I. SPENCER .OVERHOLSER, Primary Examiner f JOHN E. ROETHEL, Assistant Examiner