Axel Johnson Metals, Inc.

A. Johnson Metals Corporation

501 Axel Johnson Metals, Inc.

Howard R Harker

Charles H Entrekin

Carlos E Aguirre

Janine C Borofka

Joseph A Knecht, Ii

Robert A Borowski

In the disclosed embodiments, vacuum casting of metal ingots is effected by melting metal in a hearth, directing molten metal from the hearth through a hearth outlet to one of a series of mold segments positioned on the periphery of a rotatable drum, and directing an energy beam from an electron gun or plasma gun toward the surface of the molten metal being poured into the mold segment to control solidification of the ingot. After the mold segment has been filled, the drum is indexed to position an adjacent mold segment beneath the hearth outlet. The energy beam is directed toward the surface of the completed ingot in the adjacent segment as well as toward the mold segment being filled to form a smooth surface on the solidified ingot.

Static vacuum casting of ingots

In the representative embodiment described in the specification, an electron beam furnace has an evacuation system which maintains the interior of the furnace at a pressure in the range from about 50 microns Hg to 300 microns Hg. The relatively high pressure reduces degassing time from a cold start, suppresses volatilization of constituents of metal being refined, and causes volatilized metal to condense in powder form on a condensing screen. A vibrator assists in removing the powder from the condensing screen. The electron beam gun has a series of compartments which are individually evacuated to maintain the pressure in the compartment containing the cathode at a level less than about 1 micron Hg.

Intermediate pressure electron beam furnace

In the particular embodiments described in the specification, a vacuum furnace includes a hearth having a melting region and a refining region and a particulate metal supply tube for conveying particulate metal to one side of the melting region. Three water-cooled shield members surround the other sides of the melting region so that metal ejected from the particulate metal deposited in the melting region by explosive vaporization of inclusions in the metal is intercepted by the shield members.

Vacuum processing of particulate reactive metal

Method of operating an electron beam furnace

In the particular embodiments described in the specification, a vacuum furnace includes a conveying arrangement for holding four solid metal members with their end faces in closely-spaced relation and an energy beam gun directs energy to the adjacent faces to melt the metal. Metal ejected from the heated surfaces by explosive vaporization of inclusions in the metal is trapped by the adjacent surfaces of the other metal members.

Vacuum processing of reactive metal

In the particular embodiments of the invention described in the specification, a hearth for melting and refining metal has a hearth bed with cooling pipes so that a skull of molten metal is formed and energy input devices are directionally controlled to permit the skull to form a barrier between a melting region where solid material is introduced into the hearth and a refining region where molten material is refined before being poured into a mold. In one embodiment, the barrier formed by the skull provides a dam with a narrow channel between the melting region and the refining region, and in another form, the barrier provided by the skull consists of spaced peninsulas extending from opposite sides of the hearth to provide a serpentine path between the melting region and the refining region.

Cold hearth refining

In the embodiments described in the specification, continuous casting of ingots is carried out by transferring molten metal from a hearth to a mold through one or more flow channels which provide flow paths having a shallow angle to the horizontal and which terminates adjacent to the surface of the molten metal in the mold so that the vertical velocity component of the stream of molten metal flowing into the mold is minimal and the horizontal velocity component is low. In one form, the hearth surrounds the mold, providing four shallow-angle flow channels uniformly spaced around the periphery of the mold to avoid unilateral introduction of the molten material into the mold.

Continuous casting of ingots

Cold hearth refining apparatus

In the representative embodiment described in the specification, continuous casting of fine-grain ingots is effected by supplying molten metal to a mold in which the metal is solidified and an ingot is withdrawn downwardly and controlling the temperature in the central region of the molten metal above the ingot at a level at which small crystallites of metal are formed, but large quantities of solid material are not formed. The desired temperature level may be maintained by visual observation of the surface of the metal or pyrometric detection of the temperature of the surface and control of a directional energy input device such as an electron beam gun or a plasma torch to supply sufficient energy to maintain the desired temperature level. The typical apparatus described in the specification includes a cold hearth containing a pool of molten metal which is supplied to the mold and energy input devices, which may be electron beam guns or plasma torches, for melting the material in the hearth and maintaining the temperature of the molten material in the hearth and the mold at the desired levels, along with temperature detectors for detecting the temperature of the molten metal in the hearth and the mold, and a control unit for controlling the energy input devices for the hearth and the mold.

Continuous casting of fine grain ingots

In the particular embodiment of an electron beam furnace arrangement described in the specification, an electron beam gun unit is supported on rails for motion between two hearth and casting units, each having a lid to seal the unit when the electron beam gun unit is not in place. Sealing covers are also provided for the molds associated with the casting units. A common pump, preheating and hearth cooling unit communicates with each of the hearth and casting units so that, when one of the hearth and casting units is in use, the other unit can be cleaned and maintained and then outgassed and preheated in preparation for transfer of the electron beam gun unit from the other hearth and casting unit.

High capacity electron beam cold hearth furnace

In the particular embodiment of an electron beam cold hearth refining arrangement described in the specification, two separate hearth segments are disposed at right angles to each other and raw material is supplied to a melt area at the end of the first hearth segment remote from the second hearth segment. Molten material is poured from the opposite end of the first hearth segment into the adjacent end of the second hearth segment and refined molten material is poured into a mold from the opposite end of the second hearth segment. To prevent spattering of unrefined material into the mold or the adjacent refining area of the second hearth segment a baffle is positioned in the angle between the two mold segments.

Electron beam cold hearth refining

An electron-beam furnace for melting and refining metals in a trough-like hearth by scanning high-intensity, narrow electron beams across the hearth is provided with a wire coil located near the hearth for producing a relatively weak magnetic field in the vicinity of the molten metal in the hearth to prevent erratic local beam deflections caused by fluctuations in the plasma that forms in the vicinity of the molten metal. The use of the weak magnetic field allows the electron beams projected by remotely positioned electron guns to be accurately scanned across the hearth by deflection yokes associated with the electron guns.

Growing community of inventors

Malvern, PA, United States of America

Howard R Harker