Method for producing castings, casting apparatus, and gas-blowing nozzle used in casting apparatus

Abstract

A method for producing a casting by pouring a metal melt by gravity into a gas-permeable casting mold having a cavity comprising at least a sprue, a runner and a product-forming cavity, comprises pouring a metal melt into a desired cavity portion including the product-forming cavity through the sprue, the melt being in a volume smaller than the volume of an entire cavity of the gas-permeable casting mold and substantially equal to the volume of the desired cavity portion; supplying a gas to the desired cavity portion through the sprue before the desired cavity portion is filled with the poured melt, so that the melt fills the desired cavity portion and solidifies; the gas being supplied from a gas-blowing nozzle fit into the sprue.

1 . A method for producing a casting by pouring a metal melt by gravity into a gas-permeable casting mold having a cavity comprising at least a sprue, a runner and a product-forming cavity, comprising the steps of
 pouring a metal melt into a desired cavity portion including said product-forming cavity through said sprue, said melt being in a volume smaller than the volume of an entire cavity of said gas-permeable casting mold and substantially equal to the volume of said desired cavity portion; and   supplying a gas to said desired cavity portion through said sprue before said desired cavity portion is filled with the poured melt, so that said melt fills said desired cavity portion and solidifies;   said gas being supplied from a gas-blowing nozzle fit into said sprue.   
     
     
         2 . The method for producing a casting according to  claim 1 , wherein said gas-blowing nozzle has a side surface tapered in a gas-ejecting direction; said sprue has a wall surface tapered in a melt flow direction; and the tapered side surface of said gas-blowing nozzle is fit into the tapered wall surface of said sprue. 
     
     
         3 . The method for producing a casting according to  claim 1 , wherein said gas-blowing nozzle is pushed in the gas-ejecting direction. 
     
     
         4 . A casting apparatus comprising
 a gas-permeable casting mold having a cavity comprising at least a sprue into which a metal melt is poured, a runner constituting a flow path of said melt poured through said sprue, and a product-forming cavity to be filled with the melt supplied through said runner;   a gas-blowing nozzle for supplying a gas into a cavity of said gas-permeable casting mold through said sprue, such that a metal melt poured into said gas-permeable casting mold by gravity fills only a desired cavity portion including said product-forming cavity; and   a means for supplying said gas to said gas-blowing nozzle;   said gas-blowing nozzle having a portion fit into said sprue for supplying said gas to said cavity through said sprue.   
     
     
         5 . The casting apparatus according to  claim 4 , wherein the fitting portion of said gas-blowing nozzle has a side surface tapered in a gas-ejecting direction. 
     
     
         6 . The casting apparatus according to  claim 4 , wherein said gas-blowing nozzle has a gas-ejecting bore having a diameter increasing in a gas-ejecting direction. 
     
     
         7 . The casting apparatus according to  claim 4 , wherein
 said sprue has an introducing hole portion constituting a path through which said metal melt flows downward, and a cup portion open on said gas-permeable casting mold, which is connected to said introducing hole portion and has a larger diameter than that of said introducing hole portion; and   said introducing hole portion has a fitting portion, into which said gas-blowing nozzle is fit.   
     
     
         8 . The casting apparatus according to  claim 7 , wherein said fitting portion constituting part of said sprue has a wall surface tapered in a downward flowing direction of said metal melt. 
     
     
         9 . The casting apparatus according to  claim 4 , which has a mechanism of pushing said gas-blowing nozzle in the gas-ejecting direction. 
     
     
         10 . A gas-blowing nozzle for supplying a gas into a cavity of a gas-permeable casting mold, which comprises at least a sprue, a runner and a product-forming cavity, through said sprue, such that a metal melt poured into said gas-permeable casting mold by gravity fills only a desired cavity portion including said product-forming cavity; said nozzle having a side surface tapered in a gas-ejecting direction.