Abstract: Apparatus and method for providing a constant level of molten metal to a mold in gas permeable shell mold casting. The apparatus includes a furnace for melting and Holding metal to be cast. Structure is provided for locating a mold to be filled in casting relationship with the molten metal in the furnace and for causing molten metal to be drawn from the furnace into the mold. Structure responsive to the sensor is provided for tilting the furnace relative to the mold causing the level of the molten metal to remain constant relative to the mold as the mold is being filled.

Abstract: A system for simultaneously melting metal and holding molten metal for casting operations and the like comprises a plurality of coreless induction furnaces. Each furance has an induction coil having a plurality of coil turns. The induction coils of the furances are arranged to inductively heat metal in the furnaces and are connected in electrical series. A single power supply furnishes AC power to the series-connected induction coils. Electrical taps are located on each induction coil at spaced intervals along the coil for enabling electrical connections to be made to the induction coils at said intervals. Each interval comprises a preselected number of coil turns. Switch means are associated with each induction coil and connected to selected ones of the electrical taps for selectably switching a preselected number of coil turns into and out of circuit with the power supply for selectively melting or holding molten metal in the induction furnace associated with a selected coil.

Abstract: Apparatus and method for providing a constant level of molten metal to a mold in gas permeable shell mold casting. The apparatus includes a furnace for melting and holding metal to be cast. Structure is provided for locating a mold to be filled in casting relationship with the molten metal in the furnace and for causing molten metal to be drawn from the furnace into the mold. Structure responsive to the sensor is provided for tilting the furnace relative to the mold causing the level of the molten metal to remain constant relative to the mold as the mold is being filled.

Abstract: A levitation heating system uses only a single power supply for both levitation and heating, but permits the frequency of the power supply to be changed to control heating effects independently of levitation forces. The levitation force is kept constant by changing the apparent impedance of the induction and levitation coil as the frequency is changed, thereby providing a constant applied current to the coil over a range of applied frequencies. Feedback is employed to assure constant current in the coil.

Abstract: A process is described for removing oil from oily metal chips. Hot pressurized liquid water is continuously passed over a bed of the chips contained in a pressurized vessel. In one embodiment, the water is expanded over the chips to partially vaporize the liquid water and greatly reduce the density of the flowing stream. The density reduction increases the velocity of the stream flowing over the chips and increases the frictional cleaning effect of said stream. A water-oil mixture is continuously removed from the vessel.

Abstract: A direct current modulator provides double frequency variable A-C power to a load (such as an induction furnace or induction heater) specifically adapted to operate at the double frequency. The direct current modulator includes a saturable reactor bridge circuit having impedance balanced windings which function as magnetic valves. The windings are connected to provide first and second zero A-C potential terminals to which D-C magnetization current is connected. A source of D-C magnetization current is provided by a direct current circuit in which the modulated direct current flows. The direct current circuit includes the load, a rectifier and transformer connected to a source of A-C power. Capacitance and reactance may be provided in circuit with the load for bypassing the D-C component of the modulated D-C current which flows through the load.