Method and apparatus for casting

Abstract

A method and apparatus for casting wherein molten metal is treated to create conditions of whole volume solidification in the mold. The treating of the molten metal can include the application of vibration in specified manner under specific frequency and amplitude for causing multiple sites of crystallization throughout the mold, or the treating can be by use of activators which are formed during casting, either directly from the molten metal stream by dispersion or from a mineral which concurrently with casting is milled, to a finely ground powder, dehydrated and fed into the molten metal throughout the metal to speed solidification and crystallization at multiple sites. Solidification speed can be more than doubled while eliminating pouring defects and improving the cast metal structure. The methods are applicable to various methods of casting including continuous casting and the methods of vibrating and use of activators can be combined with improved results.

1 . A method of casting comprising:
 pouring molten metal into a mold;   treating the molten metal to create conditions of whole volume solidification in the mold;   wherein the treating includes at least one of:   vibrating the molten metal in the mold using a vibroplate supporting the mold, the vibroplate being vibrated at a frequency of 50 to 60 Hertz and an amplitude of 0.1 to 0.2 mm;   vibrating the molten metal in the mold by direct agitation of the molten metal using a vibrating waveguide in contact with the molten metal, the waveguide being vibrated at a frequency of 50 to 60 Hertz and an amplitude of 1.0 to 2.0 mm;   adding activators to the molten metal to speed solidification.   
   
   
       2 . The method of  claim 1 , wherein said treating comprises said vibrating the molten metal in the mold using said vibroplate, the direction of vibration being in a longitudinal axial direction of the solidifying casting. 
   
   
       3 . The method of  claim 1 , wherein said treating comprises vibrating the molten metal by direct agitation of the molten metal using a vibrating waveguide in contact with the molten metal. 
   
   
       4 . The method of  claim 3 , wherein the waveguide is selected from the group consisting of a refractory ceramic material, a steel rod and a water cooled agitator. 
   
   
       5 . The method of  claim 3 , wherein said vibrating is in a longitudinal axial direction of the solidifying casting. 
   
   
       6 . The method of  claim 1 , wherein said treating comprises adding activators to the molten metal and includes forming the activators during casting. 
   
   
       7 . The method of  claim 6 , wherein said forming the activators during casting includes dispersing droplets of molten metal from a molten metal stream being poured into the mold to form the activators. 
   
   
       8 . The method of  claim 7 , wherein said dispersing includes impinging a stream selected from the group consisting of an inert gas and water onto the molten metal stream to form said droplets and cooling the droplets to form the activators. 
   
   
       9 . The method of  claim 6 , wherein said forming the activators during casting includes milling a material to a finely ground powder, dehydrating the powder and feeding the dehydrated powder into the molten metal. 
   
   
       10 . The method of  claim 6 , wherein the activators are formed of a mineral. 
   
   
       11 . The method of  claim 10 , wherein the activators are formed of sodium chloride. 
   
   
       12 . The method of  claim 6 , wherein the quantity of activator added to the molten metal is approximately 100-150 kilograms per ton of cast metal. 
   
   
       13 . The method of  claim 6 , wherein the activators are formed of a material which does not disintegrate and does not chemically interact with the molten metal, the activators being vaporized by the molten metal, and wherein the method includes recovering vapor of the vaporized activators, condensing the recovered vapor, dehydrating the condensed vapor and reusing the dehydrated activator multiple times to speed solidification of molten metal. 
   
   
       14 . The method of  claim 1 , wherein said treating comprises both said step of adding activators and one of said steps of vibrating the molten metal. 
   
   
       15 . A method of casting to create conditions of whole volume solidification comprising:
 pouring a molten metal into a mold;   removing superheat from the molten metal by providing activators in the molten metal;   wherein said activators are formed during casting.   
   
   
       16 . The method of  claim 15 , including forming the activators during casting by dispersing droplets of molten metal from a molten metal stream being poured into the mold and cooling the droplets to form the activators. 
   
   
       17 . The method of  claim 16 , wherein said dispersing includes impinging a stream selected from the group consisting of inert gas and water onto the molten metal stream to form said droplets. 
   
   
       18 . The method of  claim 15 , including forming the activators during casting by milling a material to a finely ground powder, dehydrating the powder and feeding the dehydrated powder into the molten metal. 
   
   
       19 . The method of  claim 15 , wherein the activators are formed of a mineral. 
   
   
       20 . The method of  claim 19 , wherein the activators are formed of sodium chloride. 
   
   
       21 . The method of  claim 15 , wherein the quantity of activators added to the molten metal is approximately 100-150 kilograms per ton of cast metal. 
   
   
       22 . An apparatus for casting comprising:
 a mold into which molten metal can be poured;   a device which forms activators during casting and provides the activators to the molten metal for removing superheat from the molten metal to speed solidification.   
   
   
       23 . The apparatus of  claim 22 , wherein the device which forms activators during casting includes a mill for milling a material to produce a finely ground powder, a dryer for dehydrating the powder, and a feeder for feeding the dehydrated powder into the molten metal. 
   
   
       24 . The apparatus of  claim 22 , further comprising means for recovering the vapor of vaporized activators, condensing the recovered vapor, dehydrating the condensed vapor and reusing the dehydrated activator many times to speed solidification of molten metal. 
   
   
       25 . The apparatus of  claim 22 , wherein the device which forms activators during casting includes a disperser for dispersing droplets of molten metal from a molten metal stream being poured into the mold and cooling the droplets to form activators which are provided in the molten metal. 
   
   
       26 . An apparatus for casting comprising:
 a mold into which molten metal can be poured;   a waveguide for contacting molten metal in the mold for transmitting vibration from a vibrator directly to the molten metal, the vibrator vibrating the waveguide at a frequency of 50 to 60 Hertz and an amplitude of 1.0 to 2.0 mm.   
   
   
       27 . The apparatus of  claim 26 , wherein the waveguide is selected from the group consisting of a refractory ceramic material, a steel rod and a water cooled agitator. 
   
   
       28 . A method of casting comprising:
 pouring molten metal into a mold;   treating the molten metal to create conditions of whole volume solidification in the mold;   wherein the treating includes one of:
 vibrating the molten metal in the mold using a vibroplate supporting the mold, the vibroplate being vibrated at a frequency of 50 to 60 Hertz and an amplitude of 0.1 to 0.2 mm; and 
 vibrating the molten metal in the mold by direct agitation of the molten metal using a vibrating waveguide in contact with the molten metal, the waveguide being vibrated at a frequency of 50 to 60 Hertz and an amplitude of 1.0 to 2.0 mm; 
   wherein the vibration is only applied after an interval of 5-30 minutes from the time the mold is filled with molten metal and is thereafter applied intermittently at intervals of 5-30 minutes during solidification until the end of solidification.