Method and apparatus for stirring and treating continuous and semi continuous metal casting

Abstract

A method and apparatus for stirring and treating continuous and semi-continuous casting of metallic rods ( 12 ). The apparatus comprising: a stand ( 30 ) for suspending at least one electric arc electrode ( 24 ) over the upper surface of a metallic casting ( 14 ) after or during pouring, at least one electrode ( 24 ) for forming a moving electric arc ( 38 ) over the upper surface of the mettalic casting being cast, a second electrode, being the liquid metal ( 14 ), for completion of an electric circuit including said electric arc ( 38 ) and the liquid metal ( 14 ); and control means ( 34 ), connected between said apparatus and a power supply ( 36 ) and arranged to supply power to the plasma arc electrodes ( 14, 24 ), for monitoring the parameters of the electric arc ( 38 ). The invention also provides a method for casting the metallic rods ( 12 ) by using the above described apparatus.

1 . A continuous and semi-continuous casting apparatus for the production of improved-quality rods, including rod cross-sections having a aspect ratio exceeding 1.8, the apparatus comprising: 
 a) a stand for suspending at least one electric arc electrode over the upper surface of the molten metal casting after or during pouring;    b) at least one electrode for forming a moving electric arc over the upper surface of said metallic casting being cast:    c) a second electrode, being the liquid metal, for completion of an electric circuit including said electric arc and the liquid metal; and    d) control(s) mean(s) connected between said apparatus and a power supply and arranged to supply power to the plasma arc electrode(s) and monitoring the parameters of the electric arc.    
   
   
       2 . The continuous and semi continuous casting apparatus as claimed in  claim 1 , wherein a second electric circuit is provided to create a magnetic field urging said plasma arc towards the center of said upper surface of said molten metal, by said second electric circuit passes through molten metal held in a reservior and reaches said metallic component of said mold through a molten metal column formed in a feed tube.  
   
   
       3 . The continuous and semi continuous casting apparatus as claimed in  claim 1 , wherein said first electrode is hollow and means are provided for directing a stream of an inert gas, there through to impact said upper surface for preventing oxidation of the molten metal forming said upper surface and for the removal therefrom of solid impurities and the removal of casting powder if present.  
   
   
       4 . The continuous and semi continuous casting apparatus as claimed in  claim 1 , further including a refractory guard ring slightly deeped in the surface of said rod to maintain exclusion of solid impurities such as casting powder from said upper surface under the plasma arc, and to electrically insulate an upper portion of said mold from said plasma arc.  
   
   
       5 . A continuous and semi continuous casting apparatus substantially as described hereinbefore and with reference to the accompanying drawings.  
   
   
       6 . A method for continuous and semi continuous metal casting for improving quality of metallic continuous rods, said method comprising; 
 step a) continuously pouring the liquid metal into a mold for casting rods.    step b) providing at least one first electric arc electrode and positioning same slightly above the upper surface of the molten metal;    step c) providing a second electrode in electrical contact with a section of the mold being electrically conductive, and applying an electric current to said electrodes to form an arc between said first electrode and said upper surface; and    step d) continuously moving said electric arc(s) over said upper surface.    
   
   
       7 . A continuous or semi continuous casting method as claimed in  claim 6  including the use of casting powder by: 
 step a) continuously pouring a liquid metal into a mold and applying casting powder to the rod;    step b) removing the casting powder from the arc working zone. One of the ways to remove the casting powder is by blasting an inert gas such as argon over said upper surface;    step c) preventing the return of said casting powder by placing at list one refractory guard ring on said upper surface;    step d) providing at least one plasma arc electrode and positioning same slightly above said upper surface of the molten metal, inside each protecting ring;    step f) providing a second electrode in electrical contact with a section of the mold being electrically conductive, and applying an electric current to said electrodes to form an arc between said first electrode and said upper surface; and    step e) continuously moving said electric arc(s) over said upper surface.    
   
   
       8 . A continuous or semi continuous casting method as claimed in  claim 6 , wherein said electric current applied to said electrodes to form a plasma is a DC current.  
   
   
       9 . A continuous casting or semi continuous method, substantially as described hereinbefore and with reference to the accompanying drawings.