Wagstaff Engineering, Inc.

Wagstaff, Inc.

Frank E Wagstaff

Richard J Collins

David Alan Salee

Aaron David Sinden

David A Fort

William G Wagstaff

Hans Fischer

An opening 206 is provided in a system for delivering molten metal to the mold cavity 18 of a molten metal casting apparatus. A valve closure device 192, 196 is mounted at 198 to be reciprocated in relation to the opening 206 to control the flow of molten metal therethrough, and the driven end 206 of a bellows motor 208 is connected with the valve closure device at 258 to reciprocate the device in relation to the opening. A pair of concentric relatively inside and outside thimble-shaped chambers 238 and 240, 264 is circumposed about the bellows motor so that the bight portions thereof are opposed to the driven end of the motor, and interconnected with one another by a restricted liquid flow passage 270 in the screw 268. When fluid input signals are generated in the relatively outside chamber 240, 264, for the actuation of the closure device through the bellows motor, each signal is transmitted to the end of the bellows motor through the restricted liquid flow passage 270 and the relatively inside chamber 238. But when suction occurs in the opening 206 of the molten metal delivery system, the restricted liquid flow passage 270 substantially resists the transmission of relatively low pressure feedback signals to the fluid input signals from the driven end 260 of the bellows motor because of the restriction in the passage.

Molten metal admission control in casting

Balance beams are pivotally mounted on and crosswise of an elongated rack extending parallel to a trough over a series of mold cavities, valve closure devices are suspended from corresponding first end portions of the beams to throttle valve openings in the trough, float sensors are suspended from points on the opposing second end portions of the beams to contact the surfaces of molten metal columns brought to a state of equilibrium in the cavities, and the rack is elevated in relation to the cavities as molten metal is delivered to the trough, so that as the first end portions impose a desired value on the rate at which the surfaces escalate up the axes of the cavities, the second end portions elevate the suspension points for the sensors at a rate commensurate therewith, to assure that the input signals transmitted to the first portions through the fulcra for the beams, are consistent with the imposed value. Alternatively, non-contact sensors are suspended from the rack, and the input signals thereof are transmitted through an electronic controller to balance beams on the trough, either electrically to motor driven linear actuators for the balance beams, or through a device which converts the signals to pneumatic signals for pneumatically driven actuators for the beams. The desired value is imposed on the actuators from the controller, and the rack is elevated to raise the signal generation points at a rate commensurate therewith; or the opposite is done.

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.

As a reversal of previous practice, the annular body of the mold in the unit has an annular case at the bottom thereof, rather than at the top thereof. The case is relatively thick axially of the mold, so as to form the greater portion of the axial length of the mold body at the outer periphery thereof; and at the top thereof, the case has an annular plate thereon, which forms a pair of flanges that overhang the case and enable the metal casting unit to be lowered into an aperture of a casting table from above, and supported on top of the table at the flanges. Meanwhile, the case defines the lower end opening of the mold cavity, and the outlet for liquid coolant that is discharged onto the molten metal body as it emerges from the unit. Commonly, the case is monolithic, and also has an annular sump at the top thereof which is covered by the plate to form a chamber for the coolant in the sump. A graphite casting ring may be circumposed about the inner periphery of the case, to form a liner for the upper end portion of the cavity; and a refractory top ring may be circumposed about the upper end opening of the cavity, to form a hot top for the ring.

Annular metal casting unit

A casting unit 6 consists of a monolithic body which is annular in shape and has an annular flange 72 outturned about the axis and monolithically outstanding on the body at the outer periphery, a set of lugs 110 angularly spaced about the axis on the lower end portion of the body and monolithically outstanding in the aperture, and a circumferential groove 114 about the outer periphery of the body in the upper end portion, with mullions 20 monolithically upstanding therein, adjacent the outer periphery of the groove, to form ports 112.The groove is interconnected with the cavity 108 in the lower end portion of the body at the aperture; and passages, 126, 140, a graphite ring 16, and whatever else is required, are added to complete the unit 6 before it is supported in an aperture in a metal casting table 2, having liquid coolant discharge means 14 circumposed thereabout and a stool to support molten metal after being mated with the lugs. Where the liquid coolant discharge means take the form of a liquid coolant box, the housing 22, 24 of which defines the table, and the casting unit is upwardly inserted in the box, at an aperture 26 in the bottom, and abutted with the top of the chamber 14, a device 17 is provided for sensing leakage between the casting unit and the top of the chamber. The leakage is discharged in a passage 140 passing through one of the mullions to the bottom of the casting unit.

Metal casting unit

A body of partially solidified metal emerging as ingot from the exit end 10 of an open ended mold 2, is direct cooled by charging liquid coolant into an annular retention chamber 32 circumposed about the exit end opening of the mold in the body thereof, and discharging the coolant from the chamber onto the surface of the ingot through a first passage 14 opening into the exit end of the mold and communicating with the chamber at an opening 50 therein. At times, such as in the butt-forming stage, a second passage 46 is formed in the chamber which is serially interconnected with the first passage 14 at the chamber opening 50 and operable to deliver the chamber coolant to the first passage at an increased rate of flow, relative to the rate at which the coolant was charged into the chamber. Pressurized gas is forced into the coolant flow through a body 72 of solid but porous, gas-permeable material that is incorporated into the wall 60 of the second passage at a surface thereof which extends generally parallel to the flow of coolant in the second passage. In this way, the coolant is amended to discharge through the first passage 14 in a discontinuous liquid phase in which it is laden with bubbles of undissolved gas that will alter the heat transfer characteristics of the coolant on the surface of the ingot to vary the rate at which heat is lost therefrom.

Apparatus and process for direct cooling an emerging ingot with

A body of partially solidified metal emerging as ingot from the exit end of an open-ended mold, is direct cooled by discharging liquid coolant onto the surface of the ingot through a passage of the mold opening into the exit end of the mold at an aperture therein; and at times, such as in the butt-forming stage, by the added step of forcing pressurized gas into the coolant through a body of solid but porous, gas-permeable material incorporated into the wall of the passage at a surface thereof which extends generally parallel to the flow of coolant in the passage and coterminates with the exit end of the mold at the aperture to form an edge thereof. When the gas is added, the coolant discharges through the aperture in a discontinuous liquid phase in which it is laden with bubbles of undissolved gas that will alter the heat transfer characteristics of the coolant on the surface of the ingot to vary the rate at which heat is lost therefrom.

Means and technique for direct cooling an emerging ingot with gas-laden

The mold is equipped with a casting ring 6 which is formed by clamping together four generally rectilinear wall segments 8 that are, first, arranged like the sides of a picture frame about the rabbet 52 of a rectangular case 10, and then abutted together, sash-like, at their mitered ends 80, to form a ring, the casting surface 9 of which will produce the rectangular cross-sectional outline common to sheet ingot or the like, when molten metal is fed through the ring. The clamping action is produced by a set of screws 94 at the corners 10' of the case, and after the ring 6 is clamped about a pair of spaced, axially opposing lips 54 and 60 on the case and an annular plate 14 thereabove, the plate 14 is clamped to the top of the case, to secure the ring in place and seal the axial ends of the ring against fluid flow thereacross.

Means and technique for forming the cavity of an open-ended mold

Close control of the direct cooling rate is achieved by bubbling a substantially insoluble gas into the curtain-forming coolant as it is about to discharge onto the emerging ingot. The resulting bubble-entrained curtain of coolant experiences an increased velocity, and the increase is not accompanied by a reduction in the thermal conductivity of the coolant. Instead, the bubble-entrained coolant appears to have a scrubbing effect on the metal, which breaks up any film and reduces the tendency for film boiling to occur at the surface of the metal, thus allowing the process to operate at the more desirable level of nucleate boiling, if desired. This in turn makes it possible to regulate the cooling rate by selective use of the bubbling effect, including turning the effect on and off to allow film boiling to occur when desired, such as in the butt forming stage of the casting operation. The bubbling effect can also be used to regulate the cooling rate when the coolant is in short supply and/or hotter than desired.

Means and technique for casting metals at a controlled direct cooling

One end opening of an open ended mold cavity has a diameter smaller than the peripheral wall of the cavity and a molten metal mass is introduced to the cavity by continuously filling the one end opening with the mass so that the molten metal splays about the inner peripheral edge of the opening to assume a cross-section between the ends of the cavity having a divergent/convergent outline, the intermediate continuum of which between the planes of maximum divergence and minimum convergence thereof, has a peripheral outline corresponding generally to the outline of the cavity at the peripheral wall thereof. A graphite or graphite-like ring is circumposed about the axis of the cavity in the peripheral wall thereof to form a solid but fluid permeable wall section that is disposed to define the peripheral outline of the intermediate continuum of the metallic mass. A lubricating oil and a gas are delivered to grooves on the outer peripheral portion of the ring, and are caused to diffuse simultaneously through the body of the ring so as to discharge into the cavity at the inner peripheral surface of the ring while the molten metal mass is chilled and the mold and a support are reciprocated in relation to one another axially of the cavity to form the chilled mass into an elongated body of the metal.

Direct chill metal casting apparatus and technique

One or more top-opening mold cavity defining members are supported in the chamber of a coolant box adapted for the flow of liquid coolant therethrough about the members. Each member is supported in a telescoping assembly in which the top opening of the member is co-axial with an opening in the top of the chamber to enable molten metal to be introduced to the cavity of the member through the respective top openings of the chamber and the member. Moreover, each member has a greater outer peripheral diameter transverse the axis than the top opening of the chamber, and is engaged with the top of the chamber about the opening thereof in a first horizontal plane of the box. The member is also engaged with the defining surfaces of the chamber in a second horizontal plane of the box spaced below the aforesaid first horizontal plane of the box by a vertical gap. Should liquid coolant leak into the gap through this second line of engagement, it is discharged from the gap at a level below the first horizontal plane of the box, and to a point outside of the chamber at which the leakage cannot reach the cavity of the member along the first mentioned line of engagement at the top of the chamber. As a result, the top opening of the chamber need only be large enough to enable the metal to be charged through the same, and the number of openings in the top of the chamber can be increased and/or spaced more closely to one another to maximize the number of molding stations in the device.

Molding device

The mold comprises a generally rectangularly shaped, machine duplicatable band which is monolithically circumferentially continuous and inherently convexly bowed on the relatively longer and shorter sides thereof, so that it forms crowns on the opposing side walls of the ingot operatively formed therein. The bow in the relatively longer sides of the band has an inherent deflection adapted to form a crown intermediate between that adapted to compensate for shrinkage during the butt forming stage of the casting operation, and that adapted to compensate for shrinkage when the casting operation is conducted at operating speed. However, the relatively longer sides of the band are adapted to flex laterally inwardly and outwardly thereof, and there are drive means connected with the relatively longer sides of the band to flex the same, firstly relatively laterally inwardly thereof to alter the deflection to that adapted to compensate for shrinkage during the butt forming stage, and then relatively laterally outwardly thereof to alter the deflection to that adapted to compensate for shrinkage when the casting operation is conducted at operating speed.

Growing community of inventors

Veradale, WA, United States of America

Frank E Wagstaff