Centrifugal casting method and apparatus
AssigneeUnited States Pipe and Foundry Company
InventorsKenneth J Watts, Terry M Wood
Life of this patent
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Abstract
A method and apparatus for centrifugal casting, in which transfer functions are developed relating the fluidity of molten metal, for example iron of varying composition, to casting machine movement for a particular mold in order to cast objects, for example pipe, having desired and uniform characteristics, including wall thickness. Fluidity is calculated for each pour of molten metal based on the measured pour temperature and measured liquidus arrest temperature. A drive system controlled by a programmable logic controller moves the casting machine in accordance with the output of the transfer functions based on the calculated fluidity.
Claims12
A method of centrifugally casting an object from a container of molten metal, said molten metal having a liquidus arrest temperature and, when poured, a pour temperature, comprising:
- measuring the liquidus arrest temperature of the molten metal in the container;
- pouring the molten metal into a trough to deliver the molten metal to a rotating mold for a predetermined period of time, said predetermined period comprising a plurality of time segments;
- measuring the pour temperature of the molten metal poured into the trough;
- calculating fluidity of the molten metal based upon the measured liquidus arrest temperature and measured pour temperature;
- and
- moving the mold relative to the trough to dispose molten metal into the mold, wherein said movement is controlled based on said calculated fluidity and in accordance with a transfer function relating fluidity to volumetric requirements for an object of predetermined specifications on said mold, to deliver a volume of molten metal to said mold to cast said object in accordance with said predetermined specifications, wherein said transfer function comprises a plurality of equations, each said equation corresponding to an identified segment of said plurality of time segments, said equations comprising:
- (a) a first delay equation corresponding to a time segment from when molten metal leaves the end of the trough until a predetermined volume of molten metal is disposed in the mold;
- (b) a first acceleration equation corresponding to a time segment in which the flow rate of said molten metal in said trough increases after said predetermined volume of molten metal reaches said mold;
- and
- (c) a first deceleration equation corresponding to a time segment in which the flow rate of said molten metal in said trough decreases.
A method of centrifugally casting a pipe from a container of a molten alloy of iron, said molten iron having a liquidus arrest temperature and, when poured, a pour temperature, comprising:
- measuring the liquidus arrest temperature of the molten iron in the container;
- pouring the molten iron into a trough to deliver the molten iron to a rotating mold, said mold comprising sections including a bell, a spigot, and a barrel between said bell and said spigot;
- measuring the pour temperature of the molten iron poured into the trough;
- calculating fluidity of the molten iron based upon the measured liquidus arrest temperature and measured pour temperature;
- moving the mold relative to the trough to dispose molten iron into the mold, wherein said movement is controlled based on said calculated fluidity and in accordance with a transfer function relating fluidity to volumetric requirements for a pipe having a bell, a spigot, and a barrel with predetermined specifications, to deliver a volume of molten iron to said mold to cast said pipe in accordance with said predetermined specifications, wherein said transfer function comprises a plurality of equations, at least one equation corresponding to each section of said mold.
Dependencies are inferred from the claim text.