US3434823A - Method for degassing metallic melts by sonic vibrations - Google Patents

Method for degassing metallic melts by sonic vibrations Download PDF

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Publication number
US3434823A
US3434823A US417667A US3434823DA US3434823A US 3434823 A US3434823 A US 3434823A US 417667 A US417667 A US 417667A US 3434823D A US3434823D A US 3434823DA US 3434823 A US3434823 A US 3434823A
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melt
melts
degassing
current
furnace
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US417667A
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English (en)
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Alfred Adamec
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Wiener Schwachstromwerke GmbH
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Wiener Schwachstromwerke GmbH
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B4/00—Electrothermal treatment of ores or metallurgical products for obtaining metals or alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
    • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
    • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
    • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
    • B06B1/04—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism
    • B06B1/045—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with electromagnetism using vibrating magnet, armature or coil system
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/02—Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action including acoustic waves
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/02—Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action including acoustic waves
    • C22B9/026—Refining by liquating, filtering, centrifuging, distilling, or supersonic wave action including acoustic waves by acoustic waves, e.g. supersonic waves
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/04—Refining by applying a vacuum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • This invention relates to the degassing of metallic melts and, more particularlly, to an improved and simplified method therefor utilizing alternating current at low frequencies, preferably with distortion of the WEVC form of the alternating current to increase the harmonic content thereof.
  • solenoids or magnetic shields are used, which are arranged outside the housing in which the metal to be melted is located. It has also been attempted to cause the separation of metal and slags (impurities) by means of two electromagnetic fields which are arranged at certain directions relative to each other.
  • the desired objective can be achieved if the high frequency heating current in high frequency furances is kept within moderate limits, so that a certain favorable metal temperature is established, and if, at the same time, a possibly intensive stationary magnetic field is superposed on the high frequency field.
  • the ponderomotive force produced by this additional field in the melt is proportional to the product of the current density of the high frequency current and the intensity of the static magnetic field; its temporal means value is zero. We can thus obtain intensive mechanical vibrations in the bath without at the same time increasing the force of the stirring movements.
  • the foregoing disadvantages are eliminated by providing for the use of low frequency AC sources, including commercial frequencies, such as 50 cycle AC mains.
  • commercial frequencies such as 50 cycle AC mains.
  • the necessity of a separate generator is eliminated, thus providing a very substantial advantage.
  • any desired output can be attained without an undue increase in cost for a separate source.
  • the use of frequencies less than 50 cycles is, in any event, rarely desirable. In only a few cases will it be necessary to use frequencies over 50 cycles as supply frequencies, and even then these can be obtained from commercial frequencies by static frequency multiplication without having to use a separate generator.
  • an object of the present invention is to provide a method for degassing metallic melts by sonic vibrations produced in the melt by ponderomotive effects caused by alternating currents flowing through the melt.
  • the invention is characterized by the fact that, in order to use a low frequency AC source, preferabl a commercial frequency source, to produce the sound vibrations, the alternating currents are subjected to a distortion of their periodic course in order to increase their harmonics, thus enhancing the degasification.
  • another object of the invention is to provide a method for degassing a metallic melt by vibrations which are produce din the melt by ponderomotive effects caused by alternating currents in the melt and which are subjected to a distortion of their periodic course to increase their harmonic contents.
  • the presence of the deliberately produced harmonics increases the maximum velocity amplitude appearing the sonic vibrations, and thus increases the degassing effect as compared to the effect obtained using only the fundamental frequency, and while requiring only the same current input. It is this factor which permits the use of low input frequencies in the commercial frequency range.
  • a further object of the invention is to provide a method for degassing a metallic melt by sonic vibrations produced in the melts by ponderomotive effects caused by alternating currents flowing in the melts, and using, as the alternating current, the alternating current normally used to heat the melt, with the alternating current being temporarily or constantly distorted as mentioned above for degassing the melt.
  • the distortion of the alternating current in the sense of the invention can be effected by abrupt limitation of its amplitude before it reaches a periodic maximum amplitude in at least one direction of flow, so that a pulse type current fiow is produced.
  • the thus limited or clipped alternating current half waves are induced in a known manner into the melt, for example, by at least one similarly limited or clipped alternating magnetic field.
  • An increase of the ponderomotive effect can be obtained if the stationary magnetic field is superposed, in a known manner, on the melt. In cooperation with the alternating current flowing in the melt, this increases the ponderomotive effect.
  • yet another object of the invention is to provide a method for degassing metallic melts by sonic vibrations produced in the melts by ponderomotive effects caused by alternating currents in the melts and to increase the ponderomotive effects by superposing a stationary magnetic field on the alternating currents flowing in the melts.
  • apparatus for performing the method of the invention comprises a supply transformer which can be loaded beyond the saturation range of the magnetic induction.
  • the iron core of the transformer is magnetically preloaded, preferably by providing at least one DC winding thereon.
  • the primary current in at least one direction of flow effects a saturation of the magnetic induction in the iron core even before the specific values are obtained.
  • the resulting stationary magnetic field is superposed in a known manner on the AC field, so that the ponderomotive effect in the melt is also increased by the inductive action of the two fields on the melt.
  • Transformers of this type are suitable for use as transformers for induction furnaces, where the secondary circuit is formed b the molten material flowing in a closed melting channel of the furnace.
  • such a transformer can be used in a suitably dimensioned reheating furnace.
  • the distortion of the alternating current wave forms can be effected in another manner.
  • at least one rectifier, or a controllable electronic valve can be connected in the supply circuit so as to transform the alternating current to the AC portion thereof.
  • the elec- can be done by applying an initial DC 'bias to the rectifier or to the controllable electronic valves to control the ratio of the DC portion of the supply current to the DC porion thereof.
  • the electric currents can be introduced in the melt by means of electrodes such as used in so-called resistance heated furnaces.
  • the frequency of the alternating current derived from a commercial frequency source can be increased up to seven times by using so-called static frequency converters.
  • FIG. 1 is a transverse sectional view of a furnace transformer embodying the invention illustrating the iron core thereof in its initial state, with the ceramic body containing the furnace loop and the primary winding being sectioned along the center of the transformer core;
  • FIG. 2 is a top plan view of the transformer shown in FIG. 1, with a portion of the crucible shown in section;
  • FIG. 3 is a central vertical sectional view through a low pressure founding furnace embodying the invention, with a transformer, such as shown in FIGS. 1 and 2, illustrated in side elevation;
  • FIG. 4 is a front elevation view, partly in section, partly in section, of another embodiment of a melting furnace in accordance with the invention.
  • FIG. 5 is a partial top plan view of the melting furnace shown in FIG. 4;
  • FIG. 6 is a schematic wiring diagram, with a schematically illustrated furnace crucible, illustrating another arrangement embodying the invention
  • FIG. 7 is a schematic wiring diagram illustrating the principle of an electronic circuit for distorting the alternating current wave forms.
  • FIG. 8 is a transverse sectional view of a conventional arc-type resistance furnace to which the principles of the invention may be applied.
  • the transformer has a closed iron core 10 comprising three stacks of laminations mounted in juxtaposition.
  • the center stack is displaced laterally with respect to the two outer stacks, so that its right leg 10a protrudes from the right hand side of the transformer core, whereas the left legs 10a of the two outer stacks protrude from the left hand side of the transformer core.
  • the left leg of the center stack forms, with the right legs of the two outer stacks, the central leg 10!) of the transformer core which is embraced by the primary winding 11.
  • Transformer core 10 embraces a ceramic body 12 in which there is formed a heating channel 13 extending around center leg 10b. A part of channel 13, extending parallel to the plane of core 10, is closed by means of plugs 14 which can be removed for cleaning of the channel, as best seen in FIG. 2.
  • channel 13 opens into a funnel-shaped mouth 15 formed in the storage crucible 16 of the low pressure founding furnace. Month 15 opens into the bottom surface 17 of storage crucible 16.
  • a filling tube 18 is positioned inside storage crucible 16 and extends along a wall thereof from the top of the crucible.
  • the lower end of tube 18 projects into the mouth 15 of heating channel 13.
  • the open top of crucible 16 is closed by a swivel cover 19 having a pressure gas pipe 20 extending therethrough.
  • Filling tube 18, which is disposed laterally of the cover 19, is closed by means of a stopper 21 of the valve type, and communicates with a trough 22.
  • the furnace transformer is suspended on supporting elements 23 and 24.
  • the melt is to be degassed during operation of the founding furnace, at least one of the legs 10a of transformer core 10 is removed.
  • the normal magnetic field in the iron core 10 is 12,000 gauss
  • the field is increased to about 18,000 gauss so that the transformer is working in the saturation range.
  • the wave form of the current in the melt forming the secondary conductor and in the heating channel 13 is distorted without any increase in current input.
  • there is a certain degassing effect since the energy density in the cross section of the heating conductor form-ed by the melting channel 13 is rather high.
  • valve stopper 21 When molten material is to be removed from the furnace, valve stopper 21 is lifted, after which the melt will rise in filling tube 18 under the effect of pressure gas fed to pipe 20 and will flow off through trough 22. As filling tube 18 projects into the mouth 15 of channel 13, in which latter the degassing occurs and is brought about relatively rapidly, it is possible to remove continuously quantities of degassed molten material without first having to degas the entire contents of storage crucible 16. It is thus possible to operate with relatively low energy inputs, such as those merely sufiicient to keep the melt warm or molten and to degas the material that, at any given moment, is in channel 13. With a frequency of 50 cycles, the depth of penetration of the induction in iron is about 7.5 cm., and in aluminum about 3.5 cm. It will be appreciated that other embodiments of reheating and founding furnaces come within the scope of the invention as previously mentioned.
  • FIGS. 4 and 5 show a melting furnace in which, in accordance with the invention, the magnetic core of the transformer is provided with an initial DC bias or precharging.
  • a pair of DC windings 25 are mounted on the core 10 as illustrated in FIGS. 4 and 5.
  • Coils preferably are polarized in such a manner that the unidirectional magnetic fluxes resulting therefrom extend in opposite directions through the two halves of the magnetic core 10 of the transformer, especially through their outer legs 100, this core including central legs 10d through which the -DC magnetic fluxes extend in the same direction.
  • the strength of the steady magnetic fields produced by windings 25 are determined in such a manner, through the selection of the value of the DC current flowing in windings 25, that the. AC current in primary winding 11 causes, in one direction of flow, a saturation of the magnetic induction of the core 10 before the AC current attains its peak values. Thereby, the ponderometric effect in the melt is increased.
  • FIG. 6 is a schematic wiring diagram of another arrangement for superposing a stationary magnetic field on the transformer core.
  • DC current from a DC source 26 flows through a choke 27 to the induction coil 28 surrounding a melting crucible 29.
  • This induction coil is also supplied with alternating current from an AC source 30 through a condenser 31.
  • the degassing effect which the distorted alternating field has on the melt is substantially increased by the superposed DC mag netic field.
  • the steady magnetic field may be disconnected at will, and could also be produced in a winding separate from the AC induction winding 28.
  • FIG. 7 illustrates the principle of current limitation using controllable electronic valves, and which current limitation can be used with advantage, in accordance with the invention, to increase the degassing efiect.
  • the control electrode of an electronic valve 33 has a sinusoidal AC voltage applied thereto through a series resistance 34. Since the voltage applied to the control electrode through a working resistance 35, and through a resistance 36 connected in parallel with the anode and the control electrode, has a tendency to maintain a zero potential, a narrow strip is cutoff of the AC wave near the zero line.
  • the amplified output voltage corresponding to this strip, and which can be tapped from the working resistance 35 through the coupling condenser 37, has a substantially rectangular wave form and is very rich in harmonics, which enhance the degassing effect.
  • FIG. 8 is a schematic representation of a conventional resistance-type arc furnace. Its electrodes 52 have a current applied thereto, whose wave form is distorted to enhence the degassification.
  • the melt 49 which is covered by a slag layer 48, is maintained in the lining or crucible t) which is closed by means of the cover 51.
  • Carbon electrodes 52 protrude through apertures in cover 51 and into the interior of the furnace up to about the slag layer 48, so that the arcs are formed between the lower ends of the electrodes 52 and the surface of the melt 49.
  • the electrodes 52 which are suspended in holders 53, can be raised or lowered by means of these holders as required to maintain the arcs.
  • a method for degassing metallic melts by vibrations produced in the melts by ponderomotive effects produced by alternating currents traversing the melts comprising traversing the melt with low frequency alternating currents from a source thereof at substantially commercial frequencies; sharply clipping at least alternate half waves of the alternating current to reduce the peak amplitudes of said alternate half waves to increase the harmonic contents thereof to enhance the degassification of the melt; utilizing a low frequency alternating magnetic field to induce the alternating currents to traverse the melt; and clipping at least alternate half waves of the alternating magnetic field to reduce the peak amplitudes of such alternate half waves of the magnetic field.
  • theimprovement comprising traversing the melt with low frequency alternating current from a source thereof at substantially commercial frequencies; distorting the wave form of the alternating currents to increase the harmonic contents to enhance the degassification of the melts; and augmenting the ponderomotive effect by superposing a substantially constant magnetic field in the melt.
  • the improvement as claimed in claim 7 further comprising combining a variable value constant direct current potential with the pulsating direct current; and regulating the variable value direct current potential to control the ratio between the variable value direct current potential and the pulsating direct current.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Materials Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Manufacturing & Machinery (AREA)
  • Acoustics & Sound (AREA)
  • Geology (AREA)
  • Geochemistry & Mineralogy (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Environmental & Geological Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • General Induction Heating (AREA)
US417667A 1963-12-16 1964-12-11 Method for degassing metallic melts by sonic vibrations Expired - Lifetime US3434823A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
AT1006963A AT268352B (de) 1963-12-16 1963-12-16 Verfahren zur Entgasung von Metallschmelzen durch Schallschwingungen und Vorrichtungen hiezu

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US (1) US3434823A (enrdf_load_stackoverflow)
AT (1) AT268352B (enrdf_load_stackoverflow)
BE (1) BE657071A (enrdf_load_stackoverflow)
CH (1) CH428235A (enrdf_load_stackoverflow)
DE (1) DE1241996B (enrdf_load_stackoverflow)
FR (1) FR1404948A (enrdf_load_stackoverflow)
GB (1) GB1069387A (enrdf_load_stackoverflow)
SE (1) SE336416B (enrdf_load_stackoverflow)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020177530A1 (en) * 2001-04-26 2002-11-28 Kazuhiko Iwai Method for propagating vibratory motion into a conductive fluid and using the method to solidify a melted metal
US20090224443A1 (en) * 2008-03-05 2009-09-10 Rundquist Victor F Niobium as a protective barrier in molten metals
US8574336B2 (en) 2010-04-09 2013-11-05 Southwire Company Ultrasonic degassing of molten metals
US8652397B2 (en) 2010-04-09 2014-02-18 Southwire Company Ultrasonic device with integrated gas delivery system
US9145597B2 (en) 2013-02-22 2015-09-29 Almex Usa Inc. Simultaneous multi-mode gas activation degassing device for casting ultraclean high-purity metals and alloys
US9528167B2 (en) 2013-11-18 2016-12-27 Southwire Company, Llc Ultrasonic probes with gas outlets for degassing of molten metals
US10233515B1 (en) 2015-08-14 2019-03-19 Southwire Company, Llc Metal treatment station for use with ultrasonic degassing system

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1986006749A1 (fr) * 1985-05-13 1986-11-20 Maytain, Christian Procede de degazage d'une matiere en fusion et dispositif de mise en oeuvre du procede
JP3057233B1 (ja) * 1999-10-05 2000-06-26 名古屋大学長 導電性液体内疎密波発生装置

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2013653A (en) * 1933-11-07 1935-09-10 Westcott Electric Casting Corp Treatment of metals by electromagnetic forces
US2381523A (en) * 1943-12-31 1945-08-07 Ajax Engineering Corp Submerged resistor type induction furnace
US2415974A (en) * 1945-04-21 1947-02-18 Ajax Engineering Corp Submerged resistor type induction furnace and method of operating

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2013653A (en) * 1933-11-07 1935-09-10 Westcott Electric Casting Corp Treatment of metals by electromagnetic forces
US2381523A (en) * 1943-12-31 1945-08-07 Ajax Engineering Corp Submerged resistor type induction furnace
US2415974A (en) * 1945-04-21 1947-02-18 Ajax Engineering Corp Submerged resistor type induction furnace and method of operating

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020177530A1 (en) * 2001-04-26 2002-11-28 Kazuhiko Iwai Method for propagating vibratory motion into a conductive fluid and using the method to solidify a melted metal
EP1264651A3 (en) * 2001-04-26 2003-06-18 Nagoya University Method for propagating vibration into a conductive fluid and method for solidifying a melted metal using the same propagating method of vibration
US6852178B2 (en) 2001-04-26 2005-02-08 Nagoya University Method for propagating vibratory motion into a conductive fluid and using the method to solidify a melted metal
US8844897B2 (en) 2008-03-05 2014-09-30 Southwire Company, Llc Niobium as a protective barrier in molten metals
US20090224443A1 (en) * 2008-03-05 2009-09-10 Rundquist Victor F Niobium as a protective barrier in molten metals
US9327347B2 (en) 2008-03-05 2016-05-03 Southwire Company, Llc Niobium as a protective barrier in molten metals
US8574336B2 (en) 2010-04-09 2013-11-05 Southwire Company Ultrasonic degassing of molten metals
US8652397B2 (en) 2010-04-09 2014-02-18 Southwire Company Ultrasonic device with integrated gas delivery system
US9382598B2 (en) 2010-04-09 2016-07-05 Southwire Company, Llc Ultrasonic device with integrated gas delivery system
US9617617B2 (en) 2010-04-09 2017-04-11 Southwire Company, Llc Ultrasonic degassing of molten metals
US10640846B2 (en) 2010-04-09 2020-05-05 Southwire Company, Llc Ultrasonic degassing of molten metals
US9145597B2 (en) 2013-02-22 2015-09-29 Almex Usa Inc. Simultaneous multi-mode gas activation degassing device for casting ultraclean high-purity metals and alloys
US9528167B2 (en) 2013-11-18 2016-12-27 Southwire Company, Llc Ultrasonic probes with gas outlets for degassing of molten metals
US10316387B2 (en) 2013-11-18 2019-06-11 Southwire Company, Llc Ultrasonic probes with gas outlets for degassing of molten metals
US10233515B1 (en) 2015-08-14 2019-03-19 Southwire Company, Llc Metal treatment station for use with ultrasonic degassing system

Also Published As

Publication number Publication date
FR1404948A (fr) 1965-07-02
DE1241996C2 (enrdf_load_stackoverflow) 1967-12-14
SE336416B (enrdf_load_stackoverflow) 1971-07-05
BE657071A (enrdf_load_stackoverflow) 1965-04-01
CH428235A (de) 1967-01-15
GB1069387A (en) 1967-05-17
DE1241996B (de) 1967-06-08
AT268352B (de) 1969-02-10

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