Process for Producing Die-Cast Parts

Abstract

In a process for producing die-cast parts made of an aluminum alloy, the aluminum alloy is exposed to high shearing forces in a mixing and kneading machine, is removed as partially solid aluminum alloy with a predefined solids content, is transferred into a filling chamber of a die-casting machine and is introduced into a casting mold using a piston, wherein a solids content of the aluminum alloy in a working space of the mixing and kneading machine is set to a predefined solids content by cooling and heating the working space in a targeted manner.

1 . A process for producing die-cast parts made of an aluminum alloy,
 wherein the aluminum alloy is exposed to high shearing forces in a mixing and kneading machine, having a housing with a working space, which is surrounded by an inner housing sleeve, and a worm shaft, which rotates about a longitudinal axis and moves to and fro translationally in the longitudinal axis in the inner housing sleeve and is provided with kneading blades, and with kneading bolts, which are fastened to the inner housing sleeve and protrude into the working space, wherein liquid aluminum alloy is fed to the working space at one end of the housing and, at the other end of the housing, is removed from the working space as partially solid aluminum alloy with a predefined solids content, is transferred into a filling chamber of a die-casting machine and is introduced into a casting mold using a piston, wherein the solids content of the aluminum alloy in the working space is set to the predefined solids content by cooling and heating the working space in a targeted manner.   
     
     
         2 . The process as claimed in  claim 1 , wherein the inner housing sleeve is surrounded by an outer housing sleeve such that an intermediate space is formed, and cold and/or hot gases are conducted through the intermediate space for cooling and heating the working space. 
     
     
         3 . The process as claimed in  claim 2 , wherein air is conducted through the intermediate space for cooling, and hot gases are conducted through the intermediate space for heating. 
     
     
         4 . The process as claimed in  claim 2 , wherein the gases are conducted through the intermediate space in countercurrent to the direction in which the aluminum alloy is transported. 
     
     
         5 . The process as claimed in  claim 1 , wherein in order to set a desired solids content, the viscosity of the aluminum alloy in the working space is measured and set to a predefined value by cooling and heating the working space in a targeted manner. 
     
     
         6 . The process as claimed in  claim 1 , wherein the solids content of the aluminum alloy is set to 40 to 80%. 
     
     
         7 . The process as claimed in  claim 1 , wherein the partially solid aluminum alloy is removed from the working space as a partially solid metal strand, the partially solid metal strand is split into partially solid metal portions and the partially solid metal portions are transferred into the filling chamber of the die-casting machine. 
     
     
         8 . The process as claimed in  claim 1 , wherein in order to produce die-cast parts reinforced with nanoparticles, nanoparticles are mixed with the aluminum alloy and finely dispersed in the aluminum alloy by high shearing forces in the mixing and kneading machine, wherein liquid aluminum alloy and nanoparticles are fed to the working space at one end of the housing and, at the other end of the housing, are removed from the working space as partially solid aluminum alloy with a predefined solids content and with nanoparticles finely dispersed in the aluminum alloy. 
     
     
         9 . The process as claimed in  claim 8 , wherein the content of the nanoparticles in the alloy is 0.1 to 10% by volume. 
     
     
         10 . The process as claimed in  claim 9 , wherein the nanoparticles are fumed silica, carbon nanotubes (CNT) or nanoscale particles of metal or semimetal oxides. 
     
     
         11 . The process as claimed in  claim 2 , wherein the intermediate space is in the form of a hollow cylinder. 
     
     
         12 . The process as claimed in  claim 3 , wherein the air is compressed air and the hot gases are combustion gases. 
     
     
         13 . The process as claimed in  claim 6 , wherein the solids content of the aluminum alloy is set to 50 to 80%. 
     
     
         14 . The process as claimed in  claim 10 , wherein the nanoscale particles of metal or semimetal oxides include aluminum oxide (Al 2 O 3 ), titanium dioxide (TiO 2 ), zirconium oxide (ZrO 2 ), antimony(III) oxide, chromium(III) oxide, iron(III) oxide, germanium(IV) oxide, vanadium(V) oxide or tungsten(VI) oxide.