Patent ID: 6158498
Filing Date: 2000-12-12
Classification: B22D

Abstract:
In the process of casting molten metal into a form-sustaining body of metal by forcing the molten metal through an open ended mold cavity having an entry end portion, a discharge end opening, an axis extending between the discharge end opening and the entry end portion of the cavity, a starter block which is telescopically engaged in the discharge end opening of the cavity and reciprocable along the axis of the cavity, and a body of start-up material interposed in the cavity between the starter block and a first cross sectional plane of the cavity extending transverse the axis thereof, the acts of:relatively superimposing on the body of start-up material adjacent the first cross sectional plane of the cavity while the starter block is reciprocating relatively outwardly from the cavity along the axis thereof and the body of start-up material is reciprocating in tandem with the starter block through a series of second cross sectional planes of the cavity extending relatively transverse the axis thereof, successive layers of molten metal which have inherent splaying forces therein acting to distend the layers relatively peripherally outwardly from the axis of the cavity adjacent the first cross sectional plane thereof,confining the relatively peripheral outward distention of respective layers of the molten metal to a first cross sectional area of the cavity in the first cross sectional plane thereof, while permitting the respective layers to distend relatively peripherally outwardly from the circumferential outline of the first cross sectional area at relatively peripherally outwardly inclined angles to the axis of the cavity in which the layers assume progressively peripherally outwardly greater second cross sectional areas of the cavity in second cross sectional planes thereof,generating thermal contraction forces in the respective layers as the layers assume the second cross sectional areas, andcontrolling the magnitude of the thermal contraction forces in the respective layers so that the thermal contraction forces counterbalance the splaying forces in the respective layers at one of the second cross sectional planes of the cavity and thereby confer a free-formed circumferential outline on the body of metal as the body of metal becomes form-sustaining.