Apparatus For Continuous Casting of Magnesium Billet or Slab Using Electromagnetic Field and the Method Thereof

Abstract

An apparatus for continuous casting of magnesium billets or slabs using an electromagnetic field, and a method thereof compensates small solidification latent heat of magnesium, controls a solidification speed, and stirs molten metal within a mold via an electromagnetic field, thereby enabling continuous casting. The apparatus comprises a mold for continuous casting an as-cast billet or slab, a coil positioned outside the mold and adapted to allow electric current to be applied thereto, and a cooling nozzle positioned outside the mold and the as-cast billet or slab. During casting, electric current having a frequency of 2˜1,000 D or electric current of 50˜10,000 A having a frequency of 200˜200,000 D is applied to the coil. A magnesium billet or slab having enhanced inner quality can be produced at a high casting speed without surface defects by applying a low frequency or high frequency electromagnetic field to the mold during continuous casting of magnesium.

1 . An apparatus for continuous casting of magnesium billets or slabs using an electromagnetic field, comprising:
 a mold for continuous casting of an as-cast billet or slab;   a coil positioned outside the mold and adapted to allow electric current to be applied thereto; and   a cooling nozzle positioned outside the mold and the as-cast billet or slab.   
   
   
       2 . The apparatus according to  claim 1 , wherein low frequency electric current is applied to the coil, and the mold is provided with a replaceable ring at an upper portion inside the mold. 
   
   
       3 . The apparatus according to  claim 2 , wherein the ring is made of graphite. 
   
   
       4 . The apparatus according to  claim 1 , wherein the mold has a circular or rectangular cross-section, and the coil is positioned to surround the mold. 
   
   
       5 . The apparatus according to  claim 1 , wherein the cooling nozzle cools the mold, the coil, and the as-cast billet or slab by directly spraying water thereto. 
   
   
       6 . A method for continuous casting of magnesium billets or slabs using an electromagnetic field by an apparatus according to  claim 1 , wherein electric current is applied at a frequency of 2-1,000[□] Hz to a coil of the apparatus during casting. 
   
   
       7 . An apparatus for continuous casting of magnesium billets or slabs using an electromagnetic field, comprising:
 a mold for continuous casting of a magnesium billet or slab, and having a slit formed therein;   a coil positioned outside the mold and adapted to allow electric current to be applied thereto; and   an electromagnetic stirring device positioned at a lower portion of the mold.   
   
   
       8 . The apparatus according to  claim 7 , wherein the mold has segments partitioned by the slit, and a cooling water passageway formed in the segments. 
   
   
       9 . The apparatus according to  claim 8 , wherein the slit is formed at a central region of the mold, and extends from below an upper end of the mold to above a lower end thereof. 
   
   
       10 . The apparatus according to  claim 8 , wherein the slit has a width of 0.2-0.3 [□] mm, and is filled with ceramic bonds to allow the electromagnetic field to be applied to molten metal within the mold while preventing leakage of the molten metal. 
   
   
       11 . The apparatus according to  claim 7 , wherein the mold has a circular or rectangular cross-section, and the coil is provided to surround the mold. 
   
   
       12 . The apparatus according to  claim 7 , further comprising: a cooling nozzle positioned between the mold and the electromagnetic stirring device. 
   
   
       13 . The apparatus according to  claim 12 , wherein the cooling nozzle cools the as-cast billet or slab, and the electromagnetic stirring device by directly spraying water thereto. 
   
   
       14 . A method for continuous casting of magnesium billets or slabs using an electromagnetic field with an apparatus according to any one of  claims 7  to  13 , wherein during casting, electric current of 50-10,000 A is applied at a frequency of 200-200,000 [□] Hz to a coil of the apparatus, and electric current of 20-1,000 A applied at a frequency of 2-100 [□] Hz to an electromagnetic stirring device of the apparatus.