Process for the electromagnetic casting of metals involving the use of at least one magnetic field which differs from the field of confinement

Abstract

1. A process for the casting of metals wherein one electromagnetic confinement field generated by the inductor (3) applied to the liquid metal (2) and a stationary magnetic field generated by an annular coil (7) and a variable magnetic field generated by an annular coil (8) both applied above the level of liquid metal are caused to act simultaneously.

I claim: 
     
       1. In a process for the electromagnetic casting of metals wherein an electromagnetic confinement field acts on molten metal in the course of solidification to contain and form said molten metal into a desired casting, the improvement comprising the steps of applying a stationary field to said molten metal, said stationary field being generated by an annular coil supplied with direct current, and simultaneously applying a variable field to said molten metal, said variable field being generated by an annular coil supplied with alternating current, said fields being applied to the molten metal to produce radial vibrations within the metal during solidification and to limit the agitation of the molten metal, thereby improving the structure and surface condition of the cast metal. 
     
     
       2. A process according to claim 1 characterised in that the stationary field is of a value of less than 0.5 tesla. 
     
     
       3. A process according to claim 1 characterised in that the stationary field is modified by the presence of an iron core. 
     
     
       4. A process according to claim 1 characterised in that the variable field is at a frequency of from 5 to 100,000 Hertz. 
     
     
       5. A process according to claim 1 characterised in that the variable field is supplied with an alternating current at a frequency between 100 and 100,000 Hertz, said frequency being adjusted to the natural frequencies of the liquid metal, the dentrites in the course of formation or the solid mass. 
     
     
       6. A process according to claim 1 characterised in that the lower part of the annular coil generating the stationary field is above the level of the liquid metal. 
     
     
       7. A process according to claim 1 characterised in that the annular coil generating the variable field is disposed concentrically within the coil generating the stationary field.