Patent ID: 6341640
Filing Date: 2002-01-29
Classification: B22C,B22D

Abstract:
A method of casting metal objects in moulds, said method comprising the steps of:a) providing a mould having at least one casting cavity with a filling duct opening into a lowermost part of said casting cavity, b) providing a supply of molten metal with a sufficient pressure to be able to rise at least to an uppermost part of said casting cavity, c) connecting said supply to said filling duct and allowing said molten metal to fill said casting cavity or cavities by ascending to the uppermost part(s) thereof, said connecting step comprising the steps of c1) connecting said supply and said filling duct to an external riser extending upwardly to a higher level than the uppermost part of said casting cavity or cavities and capable of temporarily containing a quantity of said molten metal, c2) allowing said molten metal in said external riser to ascend toward said higher level at least until said casting cavity or cavities is/are completely filled with molten metal, c3) sensing a rising of said molten metal in said external riser, and c4) controlling the pressure of said molten metal in the supply in response to the sensed rising of said molten metal such that the external riser acts as a pressure buffer preventing both too high and too low filling rates.