Molten metal admission control in casting

Abstract

To control the admission of molten metal to a series of mold cavities through a series of valve openings in the downspouts of a trough thereabove, an elongated rack is arranged parallel to the trough, a set of balance beams is pivotally mounted on the rack, a set of valve closure devices is suspended from corresponding first end portions of the beams for throttling the openings, and a set of float sensors is suspended from points on the opposing second end portions of the beams for contact with the surfaces of the molten metal in the cavities. After an initial phase of the fill operation in which the surfaces of the molten metal reach a state of equilibrium at an intermediate elevation above the tops of the blocks, the rack is elevated in relation to the series of cavities so that as the first end portions of the beams impose a desired value on the rate at which the surfaces escalate up the vertical axes of the cavities, the second end portions raise the elevation of the suspension points for the sensors at a rate commensurate therewith so that the input signals transmitted to the first portions from the second portions through the fulcra for the beams, are consistent with the imposed value. In other versions using non-contact sensors hung from the rack, the input signals are developed electrically and transmitted through an electronic controller which either transmits them electrically to motor driven linear actuators for a set of balance beams on the trough from which the valve closure devices for the openings are suspended, or through a device which converts the electrical signals to pneumatic signals for pneumatically driven actuators for the set of trough mounted beams. In either of the latter versions, the desired value may be imposed on the actuators from the controller, and the rack elevated to raise the signal generation points of the sensors at a rate commensurate therewith, or the opposite may be done, in either case to assure that the imposed value and the input signals transmitted to the actuators for the balance beams are consistent with one another.