Die casting in investment mold

Abstract

Method and apparatus for casting a metallic material involves the steps of providing a non-metallic mold in a mold-receiving chamber disposed in at least one of relatively movable first and second members, communicating a mold cavity in the mold to a gating passage disposed in at least one of the first and second metallic members, communicating the gating passage to a shot sleeve, and flowing metallic material from the shot sleeve to the gating passage and into the non-metallic mold.

1 . A method of casting a metallic material, comprising 
 providing a non-metallic mold in a mold-receiving chamber disposed in at least one of relatively movable first and second members,    communicating a mold cavity in the mold to a gating passage disposed in at least one of the first and second metallic members,    communicating the gating passage to a shot sleeve, and    flowing metallic material under pressure from the shot sleeve to the gating passage and into the non-metallic mold.    
   
   
       2 . The method of  claim 1  including holding the mold in position in the chamber to communicate to the gating passage.  
   
   
       3 . The method of  claim 2  wherein the mold is held by a plate received in a groove of the mold.  
   
   
       4 . The method of  claim 1  including supporting the mold in position in the chamber against force of the metallic material introduced into the mold via the gating passage.  
   
   
       5 . The method of  claim 4  wherein the mold is abutted at the closed end of the mold by a support plate.  
   
   
       6 . The method of  claim 5  wherein the support plate is pressed toward the closed end of the mold.  
   
   
       7 . The method of  claim 1  wherein the metallic material is introduced into the mold which is unheated prior to being disposed in the chamber.  
   
   
       8 . The method of  claim 1  including disposing a ceramic investment shell mold in the chamber.  
   
   
       9 . The method of  claim 4  wherein the mold cavity includes a cavity region having a thickness of 0.35 inch or less.  
   
   
       10 . The method of  claim 1  wherein the mold cavity is configured as a turbocharger wheel-shaped cavity having multiple vane-forming cavity regions of said thickness spaced apart on a hub-forming cavity region.  
   
   
       11 . The method of  claim 1  wherein the mold cavity is configured as an airfoil-forming region of said thickness.  
   
   
       12 . The method of  claim 1  wherein the first and second members are relatively movable by being mounted on respective first and second platens of a die casting machine.  
   
   
       13 . The method of  claim 1  wherein the mold includes a pour cup communicated to the mold cavity by a sprue passage, said pour cup being communicated to the gating passage.  
   
   
       14 . The method of  claim 1  including evacuating the mold cavity to subambient pressure.  
   
   
       15 . The method of  claim 14  evacuating the mold cavity via the shot sleeve communicated thereto.  
   
   
       16 . The method of  claim 15  wherein the subambient pressure is about 100 microns or less.  
   
   
       17 . The method of  claim 1  including melting the metallic material in a vacuum chamber communicated to the shot sleeve.  
   
   
       18 . The method of  claim 1  wherein the metallic material is selected from the group consisting of titanium alloy, titanium aluminide, nickel base superalloy, and cobalt base superalloy.  
   
   
       19 . The method of  claim 1  wherein a plunger in the shot sleeve is moved in response to hydraulic pressure to flow the metallic material and wherein the hydraulic pressure is vented to a sump a preselected distance before the end of the injection stoke of the plunger.  
   
   
       20 . Casting apparatus, comprising: 
 a) relatively movable first and second members at least one of which includes a mold-receiving chamber and at least one of which includes a gating passage for receiving metallic material from a shot sleeve,    b) a non-metallic mold disposed in the chamber in a position to receive the metallic material from the gating passage, and    c) means communicated to the shot sleeve for flowing metallic material under pressure through the gating passage into the non-metallic mold.    
   
   
       21 . The apparatus of  claim 20  wherein the mold comprises a ceramic investment shell mold.  
   
   
       22 . The apparatus of  claim 20  wherein the first and second members are connected to respective first and second platens of a die casting machine, said first and second platens being relatively movable.  
   
   
       23 . The apparatus of  claim 20  wherein the means for flowing comprises a plunger in the shot sleeve.  
   
   
       24 . The apparatus of  claim 23  wherein the plunger is moved in response to hydraulic pressure and a hydraulic pressure control system includes means for venting hydraulic pressure to a sump at a preselected distance before the end of the injection stoke of the plunger.  
   
   
       25 . The apparatus of  claim 20  includes a mold-holding member in the chamber for holding the non-metallic mold in said position.  
   
   
       26 . The apparatus of  claim 24  wherein the mold-holding member comprises a plate received in a groove on the mold.  
   
   
       27 . The apparatus of  claim 20  including a mold-supporting member in the chamber for supporting the mold against force of the metallic material introduced into the mold via the gating passage.  
   
   
       28 . The apparatus of  claim 27  wherein the mold-supporting member comprises a support plate abutting a closed end of the mold.  
   
   
       29 . The apparatus of  claim 28  wherein the support member is pressed toward the closed end of the mold.  
   
   
       30 . The apparatus of  claim 20  wherein the mold includes at least one mold cavity that includes a cavity region having a thickness of 0.100 inch or less.  
   
   
       31 . The apparatus of  claim 30  wherein said at least one mold cavity is configured as a turbocharger wheel-shaped cavity having multiple vane-forming cavity regions of said thickness spaced apart on a hub-forming cavity region.  
   
   
       32 . The apparatus of  claim 30  wherein said at least one more mold cavity is configured as an airfoil-forming region of said thickness.  
   
   
       33 . The apparatus of  claim 20  wherein the mold includes a pour cup communicated to one or more mold cavities by a sprue passage, said pour cup being communicated to the gating passage.  
   
   
       34 . The apparatus of  claim 20  including means for evacuating the interior of the mold to subambient pressure.  
   
   
       35 . The apparatus of  claim 34  wherein said means comprises the shot sleeve which is under subambient pressure and communicated to the mold interior.