Vacuum die-casting method for producing castings of nonferrous alloys

Abstract

A vacuum die-casting method for producing castings of nonferrous alloys, comprising the steps of: keeping a material of nonferrous alloy in a molten state in a holding furnace; transferring a preset amount of material from the furnace to a die, at injectors; compressing the material in the die and allowing it to cool. The material, during the various steps, is continuously protected from contact with air, in regions not occupied by containment elements, by an atmosphere of gas which protects from contaminations and from the danger of oxidation, the gas having a higher relative density than air.

What is claimed is:  
     
         1 . A vacuum die-casting method for producing castings of nonferrous alloys, comprising the steps of: 
 keeping a material of nonferrous alloy in a molten state in a holding furnace;    transferring a preset amount of said material from the furnace to a die, at injectors;    compressing the material in the die and allowing it to cool,    wherein said material, during the various steps, is continuously protected from contact with air, in regions not occupied by containment means, by an atmosphere of gas which protects from contaminations and from the danger of oxidation, said gas having a higher relative density than air.    
     
     
         2 . The method according to    claim 1   , further comprising the step of degassing continuously during holding, by means of a rotor, the material contained in a withdrawal section of the holding furnace.  
     
     
         3 . The method according to    claim 2   , comprising the step of filtering the molten material during transfer from a section for filling with the material in the solid state to the withdrawal section, said sections being comprised within the holding furnace.  
     
     
         4 . The method according to    claim 1   , comprising the step of transferring a preset amount of material into said die by means of a ladle, with adjustment of the amount of material withdrawn by tipping the ladle.  
     
     
         5 . The method according to    claim 4   , further comprising the step of heating said ladle at the holding furnace before withdrawing the material.  
     
     
         6 . The method according to    claim 4   , wherein the molten material is poured into the injectors by means of said ladle with an adjustable tipping rate.  
     
     
         7 . The method according to    claim 1   , comprising the step of producing a vacuum inside the injectors and the die after the injector filling step.  
     
     
         8 . The method according to    claim 1   , comprising the step of using nitrogen as a protective gas.  
     
     
         9 . An apparatus for performing a method according to    claim 1   .