Apparatus for forming metal castings and method for forming metal casting performed by the apparatus

Abstract

An apparatus for forming metal castings, particularly with hydraulic connection between the holding furnace and the mold and a method performed by the apparatus, the hydraulic connection comprising: at least one duct ( 36 ) for connecting the holding furnace ( 11 ), which contains the molten metal ready for molding, to one or more inlets ( 12 ) for introducing metal into the cavity ( 13 ) of a corresponding mold ( 14 ); and a piston pump ( 15 ), interposed between portions ( 20, 21 ) of the duct ( 36 ), for pumping a controlled quantity of metal through the one or more inlets into the cavity, the piston pump being connected to an electronic control unit ( 16 ).

1 - 22 . (Cancelled)  
   
   
       23 . An apparatus for forming metal castings, with hydraulic connection between the holding furnace and the mold, wherein said hydraulic connection comprises: 
 at least one duct for connecting the holding furnace, which contains the molten metal ready for molding, to one or more inlets for introducing the metal into the cavity of a corresponding mold; and    pumping means, interposed between portions of said duct, for pumping a controlled quantity of metal through said one or more inlets into said cavity, said pumping means being connected to an electronic control unit.    
   
   
       24 . The apparatus of  claim 23 , comprising level measurement devices for measuring the level of the metal, which are arranged proximate to said one or more inlets and are connected to said control unit.  
   
   
       25 . The apparatus of  claim 23 , wherein said duct comprises a first portion that extends from said holding furnace and is connected to said pumping means, from which at least one second portion extends for connection to the cavity of the mold.  
   
   
       26 . The apparatus of  claim 23 , wherein said pumping means comprise a piston pump and at least one first and second valves for controlling the flow of metal, said valves being arranged respectively upstream and downstream of said piston pump, said first and second valves being adapted to prevent the return of the metal in the direction from the mold to the holding furnace, said piston pump and said first and second valves being actuated by said electronic control unit.  
   
   
       27 . The apparatus of  claim 26 , wherein said piston pump comprises a first piston, which can slide hermetically within a corresponding first cylinder that is fixed to the head of a first stem of a first actuator whose stroke is controlled by said control unit.  
   
   
       28 . The apparatus of  claim 27 , wherein said first actuator is hydraulic.  
   
   
       29 . The apparatus of  claim 26 , wherein said first and second valves are each constituted by a second piston, which can slide hermetically within a corresponding second cylinder that is fixed to the head of a second stem of a second actuator that is controlled by said control unit.  
   
   
       30 . The apparatus of  claim 29 , wherein the second actuators are pneumatic.  
   
   
       31 . The apparatus of  claim 25 , wherein said hydraulic connection comprises a reservoir that is arranged downstream of said second portion and from which at least one riser tube extends for introducing molten metal into said cavity.  
   
   
       32 . The apparatus of  claim 31 , wherein said hydraulic connection comprises a distribution unit, which is suitable to form said one or more inlets for introducing the metal into said cavity, said distribution unit being connected to said at least one riser tube, at which said level measurement devices are arranged.  
   
   
       33 . The apparatus of  claim 23 , wherein said one or more inlets are arranged below said mold.  
   
   
       34 . The apparatus of  claim 23 , wherein said one or more inlets are arranged laterally to said mold.  
   
   
       35 . The apparatus of  claim 23 , wherein said one or more inlets are arranged laterally and below said mold.  
   
   
       36 . The apparatus of  claim 24 , wherein said level measurement devices are induction devices.  
   
   
       37 . The apparatus of  claim 24 , wherein said level measurement devices are induction devices adapted to act as temperature measurement devices.  
   
   
       38 . The apparatus of  claim 23 , wherein said hydraulic connection comprises heating devices for heating said molten metal, said devices being connected to said control unit.  
   
   
       39 . The apparatus of  claim 38 , wherein said heating devices are constituted by heating resistors, each arranged within a corresponding longitudinally extended ceramic container.  
   
   
       40 . The apparatus of  claim 23 , wherein said hydraulic connection comprises sensors for sensing the temperature of said molten metal, said sensors being connected to said control unit.  
   
   
       41 . The apparatus of  claim 40 , wherein said temperature sensors are constituted by thermocouples, each arranged inside corresponding longitudinally extended ceramic containers.  
   
   
       42 . A method for forming metal castings, which uses a duct for connection between a holding furnace, which contains molten metal ready for molding, and one or more inlets for introducing the metal in the cavity of a mold, comprising the steps of: 
 controlling the level of the molten metal, keeping it close below said one or more inlets for introducing the metal in the cavity of said mold;    feeding the cavity of the mold with a chosen quantity of metal at a controlled pressure, making the level of said metal rise;    continuing to feed the cavity of the mold, keeping the metal under pressure, until the solidification step ends;    lowering the level of the molten metal to a chosen height close below said inlets;    ending the formation of the casting;    extracting the casting from the mold.    
   
   
       43 . The method of  claim 42 , wherein said control of the level of the molten metal is performed by way of level measurement devices, which are arranged proximate to said one or more inlets, and pumping means, which are interposed in said connecting duct, for pumping a controlled quantity of metal, which are connected to an electronic control unit.  
   
   
       44 . The method of  claim 42 , wherein said lowering and rise of the level of the molten metal are performed by way of said pumping means.