Method and apparatus for producing components from metal and/or metal matrix composite materials

Abstract

Method and apparatus for producing semi-finished or finished products from metal-based material. The apparatus includes a mixing furnace to receive a metal-based material to be formed; temperature control means to maintain the metal-based material in a thixotropic semi-solid state in the mixing furnace; rotatable mixing means operable in the mixing furnace to subject the metal-based material to a mixing and shearing action while imparting a centrifugal force; and supply means to move the material to a delivery site. Optionally, injection means are provided to inject the material from an introduction chamber of a casting machine into a mold or die cavity while the material is in a thixotropic semi-solid state.

1 . A method of producing semi-finished or finished products from a metal-based material, the method including the steps of: 
 (i) maintaining the material in a mixing furnace in a thixotropic semi-solid state;    (ii) subjecting the material to a continuous shearing and mixing action and centrifugal force while in the thixotropic semi-solid state within the mixing furnace to form at least in part a fine, globular microstructure; and    (iii) delivering the material involutely from the mixing furnace while in the thixotropic semi-solid state to a delivery site for solidification.    
     
     
         2 . A method according to  claim 1  including stirring the metal-based material in the thixotropic semi-solid state within the mixing furnace with shearing and mixing means acting about an upright axis to provide the continuous shearing action, the material in the thixotropoic semi-solid state being delivered tangentially through discharge means leading from the mixing furnace under forces applied by the shearing and mixing means.  
     
     
         3 . A method according to  claim 1  wherein the metal-based material includes a metal matrix composite material, the method further including the step of introducing a particulate material into the mixing furnace while the metal-based material is subjected to the continuous shearing and mixing action to form the metal matrix composite material therein, the particulate material being mixed substantially evenly through the metal matrix composite material.  
     
     
         4 . A method according to  claim 1  wherein the metal in the metal-based material selected from the group consisting of superplastic alloys, aluminium, magnesium, tin, copper, zinc, alloys of the aforesaid metals, and mixtures thereof.  
     
     
         5 . A method according to  claim 3  wherein the particulate material is selected from the group consisting of ceramic balls, ceramic particles, micro spheres, fly ash, and mixtures thereof.  
     
     
         6 . A metallic material-making apparatus for producing semi-finished or finished parts from a metal-based material, the apparatus including: 
 i) a mixing furnace to receive a metal-based material;    ii) temperature control means associated with the mixing furnace to maintain the material in a thixotropic semi-solid state;    iii) rotatable mixing and shearing and propelling means operable in the mixing furnace to subject the material in the thixotropic semi-solid state to a shearing and mixing action and a centrifugal force;    iv) supply means to duct the material involutely in the thixotropic semi-solid state from the mixing furnace to a delivery site for solidification into a near-net shape.    
     
     
         7 . A metallic material-making apparatus according to  claim 6  further including delivery means to meter a desired volume of particulate material into the mixing furnace to form the metal-based material therein, the particulate material being substantially evenly distributed through the metal-based material.  
     
     
         8 . A metallic material-making apparatus according to  claim 6  wherein the rotatable mixing and shearing and propelling means includes a plurality of upright blade means spaced radially from an axis of rotation, each the blade member being angled relative to a circumferential direction, with a rear edge zone relative to the direction of rotation of each blade member being a radially outermost dimension of each blade member.  
     
     
         9 . A metallic material-making apparatus according to  claim 8  wherein each blade member forms an angle of about 30 degrees with the circumferential direction.  
     
     
         10 . A metallic material-making apparatus according to  claim 8  wherein the rear edge zone is spaced from an inner wall surface of the mixing furnace by a distance of between 10 and 30 mm.  
     
     
         11 . A metallic material-making apparatus according to  claim 7  wherein the delivery means is positioned to deliver the particulate material to a circumferential zone traversed by the upright blade means.  
     
     
         12 . A metallic material-making apparatus according to  claim 6  wherein the rotatable means includes a central body section adapted to occupy a central zone of the mixing furnace, the central body section having a cylindrical outer surface with a diameter at least 10% of an internal diameter of the mixing furnace.  
     
     
         13 . A metallic material-making apparatus according to  claim 12  wherein the diameter of the central body section has a diameter of between 15% and 35% of the diameter of the mixing furnace.  
     
     
         14 . A metallic material-making apparatus according to  claim 6 , further including first pump means to move the metal-based material in the thixotropic state from the mixing furnace to the delivery site.  
     
     
         15 . A metallic material-making apparatus according to  claim 6 , wherein the supply means has an exit passage leading from the mixing furnace in a tangential direction whereby flow along the exit passage of the metal-based material is achieved by rotation of the mixing means.  
     
     
         16 . A metallic material-making apparatus according to  claim 6  wherein the supply means includes an exit passage leading from a central zone of the mixing furnace.  
     
     
         17 . A metallic material-making apparatus according to  claim 6  wherein the supply means includes an exit passage leading from a side zone of the mixing region.  
     
     
         18 . A metallic material-making apparatus according to  claim 15 , wherein the exit passage is located proximate a mid region of a side zone of the mixing furnace.  
     
     
         19 . A metallic material-making apparatus according to  claim 6 , further including: 
 intermediate pump means to move the metal-based material in a thixotropic semi-solid state from the mixing furnace to an intermediate holding furnace, the material being maintained in the intermediate holding furnace in a thixotropic semi-solid state, and    casting pump means to move the material from the intermediate holding furnace while in a thixotropic semi-solid state to the delivery site.    
     
     
         20 . A metallic material-making apparatus according to  claim 19  wherein the intermediate and casting pump means include a device selected from the group consisting of a piston, a screw, an electromagnetic pump, and combinations thereof.  
     
     
         21 . A metallic material-making apparatus according to  claim 6 , further including a holding furnace to which the metal-based material is delivered and is held in a molten or semi-molten state prior to being delivered therefrom to the mixing furnace.  
     
     
         22 . A metallic material-making apparatus according to  claim 6  wherein return means is provided to duct any metal-based material that is not required for casting from the delivery site to the mixing furnace.  
     
     
         23 . A metallic material-making apparatus according to  claim 6 , further including injection means to inject the material from an introduction chamber of a casting machine into the casting machine while in a thixotropic semi-solid state.