Casting process and casting machine for metals

Abstract

A casting method for metals, in particular lead and/or zinc, including: feeding the metal into a heated barrel, conveying the metal in the direction of a discharge opening of the barrel by rotational movement of a screw conveyor arranged in the barrel, and melting the metal and/or keeping it molten, with the result that the metal is present substantially entirely in the liquid phase at least in a subregion at the discharge opening of the barrel. The method further includes ejecting the metal which is present substantially entirely in the liquid phase through the discharge opening of the barrel by an axial piston movement of the screw conveyor, as a result of which the ejected metal at least partially fills at least one mold cavity, and cooling the metal, with the result that it is molded in the at least one mold cavity.

1 . A casting method for metals, in particular lead and/or zinc, the method comprising:
 feeding a metal into a heated barrel,   conveying the metal in the direction of a discharge opening of the barrel by a rotational movement of a screw conveyor arranged in the barrel,   melting the metal and/or keeping it molten, with the result that the metal is present substantially entirely in the liquid phase at least in a subregion at the discharge opening of the barrel,   ejecting the metal which is present substantially entirely in the liquid phase through the discharge opening of the barrel by means of an axial piston movement of the screw conveyor, as a result of which the ejected metal at least partially fills at least one mold cavity, and   cooling the metal, with the result that it is molded in the at least one mold cavity.   
     
     
         2 . The casting method according to  claim 1 , wherein the metal is fed into the barrel in a solid phase. 
     
     
         3 . The casting method according to  claim 2 , wherein the metal is brought into a granular form by being comminuted before it is fed to the barrel. 
     
     
         4 . The casting method according to  claim 1 , wherein the barrel is brought to, and preferably kept at, a temperature above the melting point of the metal at least between a feed site of the metal and the discharge opening. 
     
     
         5 . The casting method according to  claim 1 , wherein strip heaters on the barrel and/or an induction heater and/or infrared radiation is/are used to melt the metal or to keep it molten. 
     
     
         6 . The casting method according to  claim 1 , wherein only so much metal that a partial filling is present in the barrel, preferably a partial filling of less than 95%, 90%, 80% and/or 70%, is fed into the barrel. 
     
     
         7 . The casting method according to  claim 1 , wherein a non-return valve is used at a leading end of the screw conveyor. 
     
     
         8 . The casting method according to  claim 7 , wherein a non-return valve that can be actively actuated, preferably mechanically, is used. 
     
     
         9 . The casting method according to  claim 1 , wherein a shut-off nozzle is used at the discharge opening of the barrel to selectively open the discharge opening. 
     
     
         10 . The casting method according to  claim 1 , wherein, when ejected out of the barrel, the metal is poured into the at least one mold cavity under pressure, wherein a maximum pressure preferably lies below 2000 bar and/or 1500 bar and/or 1300 bar. 
     
     
         11 . The casting method according to  claim 1 , wherein an inert atmosphere and/or a protective vacuum is/are used in the barrel and/or in the at least one mold cavity and/or in a connecting channel between the barrel and the mold cavity. 
     
     
         12 . The casting method according to  claim 1 , wherein a pressure accumulator is used, which is in pressure-active connection with the molten metal fluidically downstream of the screw conveyor, preferably fluidically downstream of the non-return valve, preferably in the region of a connecting channel between the barrel and the mold cavity. 
     
     
         13 . The casting method according to  claim 1 , wherein a casting mold containing the at least one mold cavity is temperature-controlled, in particular is heated during a filling operation and/or cooled in order to cool the metal. 
     
     
         14 . The casting method according to  claim 1 , wherein a screw conveyor is used, which has a screw geometry with a compression ratio of between 1.0 and 1.4 and/or between 1.1 and 1.3 and/or between 1.15 and 1.25. 
     
     
         15 . A casting machine for molding metals, in particular lead or zinc, suitable in particular for carrying out the casting method according to  claim 1 , with
 a barrel,   a feed device for feeding the metal into the barrel,   a heating device, which is set up and adjusted so as to melt the metal present in the barrel and/or to keep it molten, with the result that it is present substantially entirely in the liquid phase at least in a subregion at a discharge opening of the barrel, and   a screw conveyor in the barrel and a screw conveyor drive, wherein the screw conveyor drive is formed to cause the screw conveyor to perform rotational movements and axial piston movements, and wherein the metal present substantially entirely in the liquid phase is conveyable in the direction of the discharge opening of the barrel as a result of the rotational movement of the screw conveyor and is ejectable through the discharge opening of the barrel as a result of the axial piston movement of the screw conveyor to at least partially fill at least one mold cavity with the metal.   
     
     
         16 . A use of the casting machine according to  claim 15 .