US3189957A - Method of manufacturing permanent magnets by continuous castings - Google Patents

Method of manufacturing permanent magnets by continuous castings Download PDF

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Publication number
US3189957A
US3189957A US261255A US26125563A US3189957A US 3189957 A US3189957 A US 3189957A US 261255 A US261255 A US 261255A US 26125563 A US26125563 A US 26125563A US 3189957 A US3189957 A US 3189957A
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Prior art keywords
rod
melt
sec
alloy
permanent magnets
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US261255A
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English (en)
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Luteijn Anthonie Izaak
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US Philips Corp
North American Philips Co Inc
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US Philips Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F1/00—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
    • H01F1/01—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials
    • H01F1/03—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity
    • H01F1/032—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials
    • H01F1/04—Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties of inorganic materials characterised by their coercivity of hard-magnetic materials metals or alloys
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C19/00—Alloys based on nickel or cobalt
    • 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
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S264/00—Plastic and nonmetallic article shaping or treating: processes
    • Y10S264/58—Processes of forming magnets

Definitions

  • the invention relates to the manufacture of permanent m-agnets, particularly magnetically-anisotropic alnico-type permanent magnets having a directional-grain or crystal structure and consisting of an alloy of about to 42% cobalt, about 10 to 20% nickel, about 6 to 10% aluminium and the remainder principally iron.
  • the alloy may also contain additional elements such as up to about 8% copper, up to about 4% niobium, up to about 8% tantalum wherein the niobium and/or tantalum may be partially replaced by titanium.
  • Patent 2,578,407 it was possible to cast magnet bodies about 1 inch in diameter and l inch long and obtain therefrom magneticallyanisotropic magnets with a (BH)max of slightly less than 3,l89,957 Patented June 22, 1965 ICC tion, to obtain directional-grain magnetically-anisotropic alnico magnets having a (BH)mX of about 6 to 7,. this could be done only by means of methods which were so expensive and complicated as to make such magnets cornmercially-impractical for most applications, particularly the important iield of loudspeaker plug magnets.
  • the main object of the invention is to overcome the above-mentionedI disadvantages of directional-grain methods and to manufacture in a simpler and less expensive manner directional-grain magnetically-anisotropic permanent magnets having magnetic properties which are at least as good as those of magnets produced by present-day mass production methods, for instance (BHLMx of at least 6 m.g.o.
  • a further object is to provide a method of manufacturing such magnets without waste of material i.e. with substantially utilization of the melt.
  • Another object of the invention is to provide a method of manufacturing elongated or rod-shaped magnet bodies whose magnetic properties are uniform throughout their length so that shorter magnet bodies cut therefrom will have uniform magnetic properties.
  • I continuously feed a melt of an alnico alloy of the above-composition to one end of a tubular shaped mold which defines a freezing or solidiiication zone and whose other end is closed by a support or starting rod and move the support axially in a predetermined manner, preferably with a step-wise movement, while withdrawing substantially all of the heat of solidification in the directionof movement to thereby progressively solidify successive portions of the melt while in the solidiiication zone and form a rod shaped magnet body with a uniform and intensive directional-grain structure.
  • the movement of the melt while in the solidiiication zone is very important, both as to speed and type of movement.
  • speed should be maintained substantially constant and at a predetermined rate which is less than about 0.1 mms] sec.
  • the method l employ a step-wise movement in which the length of the time periods during which the material remains stationary and the velocity during the moving periods are maintained within predetermined values which are correlated.
  • the (BHLmX- ⁇ value depends upon the degree of axial crystal orientation which can be obtained in such a way that (BI-I)mx-values more than 6 106 g.o. are only obtainable with a high degree of crystal orientation. If no crystal orientation is present the (BH)maX-value is about 5 106 g.o. Between the last mentioned (BH)mX-value and the (BH)mx-value of 6 l0 g.o. there is a range in which partial crystal orientation occurs and for this reason the methods according to the invention might be applied as well.
  • the rod-shaped bodies can be drawn from a tube of about 10 cm. long with a velocity of 0.1-10 mms./ sec. combined with stationary periods which vary between about 10 see-200 sec., the lower velocities being used with the shorter stationary periods. If these conditions are not followed, particularly the minimum stationary alsace? periods, and whenl using continuous movement the maximuc velocity, rods are obtained with poor surface conditions and often breakage occurs. Furthermore, there is hardly any crystal orientation and consequently the (BH),mx-value is less than5 106 g.o.
  • a velocity during each step of 10 mms/sec. and stationary periods of 180 sec. can be used. If this (BH)mx-value is to be obtained with a velocity during each step of 5 mms/sec. then accordingly smaller stationary periods should be chosen, for example, between 30 and 60 sec. If, on the contrary, with the velocities as mentioned above, shorter stationary period are chosen, lower (BH),x-values are obtained. The same effect occurs if with the same stationary period the velocities are chosen higher.
  • FIG. 1 is a schematicv diagram of apparatus used in carrying out the invention
  • FIG. v2 is an enlarged view of a portion of FIG. 1 and FIG. 3 is a graph showing relationship between velocity and time during which the material is stationary.
  • the material 1 which is the alloy from which the magnet is to be formed and is in a granular lform, is placed in a hopper 2 from which it is driven into a crucibley 4 by means of a screw 3 rotated at an adjustable speed by a suitable drive mechanism (not shown).
  • Alloy 1 consists essentially of about 15 to 42% cobalt, about 10 to 20% nickel, about 6 to 10% aluminium, and the balance principally iron. In the specific example to be discussed I use an alloy of 24% cobalt, 14% nickel, 8% aluminium, 3% copper, J/z% niobium and remainder iron.
  • the Crucible 4 consists of a ceramic container Whose lower end 5 forms a tubular mould having a cross section the same as that of the elongated magnet body to be formed, in this case a rod-shaped body having a diameter of about 10 to 20 mms.
  • a highfrequency coil 6 Surrounding crucible l is a highfrequency coil 6 which is supplied from a suitable source (not'shown) and which serves to form a melt 7 from the alloy material 1.
  • the upper portion of the Crucible is lled with an inert or non-oxidizing atmosphere, such as argon, helium, or hydrogen, which enters through an inlet opening 8 and leaves through an outlet 9.
  • the crucible is jacketed with heat-insulating material 10.
  • a resistance heating coil 11 which assists in controlling the direction of Withdrawal of the heat of solidication, surrounds mould 5 and is supplied from a suitable source (not shown).
  • the lower end of mould 5 is closed by a rod-shaped body 12 which may be of iron or of the same material as the melt 7.
  • Body 12 is given a predetermined axially motion M by two wheels 13 which may be rotated at variable speeds with either a uniform or stepwise movement by means of suitable driving mechanisms which are well-known in the art.
  • the mould 5 denes a solidication zone 14.
  • the rod-shaped body being formed passes through a water-cooled device 15 of suitable construction.
  • Bodies 16 having a length of several meters are cut from the rod being formed and are subjected to a magnetizing and heat-treating apparatus 17 in which they are made magnetically anisotropic in known manner. Bodies 16 are then cut into pieces of small length, for instance 10 to 20 mm. for loudspeaker magnets which small pieces are then finally magnetized in an axial direction; the above-mentioned heat-treatment may be applied to the small bodies rather than to bodies 16.
  • the rod-shaped magnet body 16 having a diameter of about 14 mm. and consisting of an alloy comprising 24% Co, 14% Ni, 8% Al, 3% Cu, 0.5% Nb, balance principally Fe, was given a continuous movement of 0.01 mm./sec.
  • the abovementioned heat-treatment-magnet bodies having a length of about 15 mm. separated, for instance by a saw from the rod-shaped body and magnetized axially, were found to have a (BI-Dm,X of 7.9 m.g.o. at a remanence of 13450 gauss and a coercive force of 770 oersted.
  • Preferred embodiments of the invention are obtained by using a discontinuous or stepwise movement of the rod-shaped magnet body, said embodiments being carried out with alloys of the specic composition as given above for the continuous movement.
  • the velocity (d in mm./ sec.) is given on the vertical axis and the stationary periods (t in sec.) are given on the horizontal axis.
  • (BI-l)max value increases from about y5 m.g.o. to 8 m.g.o. as the time of the stationary period increases from a value of 30 sec. to 180 sec. respectively, (coercive force 710-780 oersted, remanence 12500-13200 gauss). Furthermore, it can be seen that with a constant value of the time of the stationary period, of 30 sec., the (BH)mx increases from a value of about 5 m.g.o. to 8.8 m.g.o. (coercive force 710-790 oersted, remanence 12500-13600 gauss) as the velocity decreases from 10 nim/sec. to 2 ram/scc. respectively. Generally it can thus be derived that for every preselected (BH)maX value obtainable, e.g. lying between 8.0 to 8.5 m.g.o., the time of the stationary period is longer as the velocity is larger.
  • the following table shows the uniformity in the magnetic properties which are obtained.
  • the magnetic proprties of three pieces (cut from the center and the ends) of a 2 meter rod are given, the alloy being the same as mentioned in the previous examples.
  • a rod-shaped body is formed having cross-sectional dimensions for which, after magnetization, the rod has a (BI-I)max of at least 6.0 106 gauss-oersted.
  • MICHAEL V. BRINDISI Primary Examiner.
  • MARCUS U. LYONS Examiner.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Power Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Hard Magnetic Materials (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
  • Grinding And Polishing Of Tertiary Curved Surfaces And Surfaces With Complex Shapes (AREA)
US261255A 1956-05-04 1963-02-27 Method of manufacturing permanent magnets by continuous castings Expired - Lifetime US3189957A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL206892 1956-05-04
NL289045 1963-02-15

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US (1) US3189957A (xx)
BE (1) BE643866A (xx)
CH (2) CH365395A (xx)
DE (1) DE1433766B2 (xx)
DK (1) DK117444B (xx)
GB (2) GB860127A (xx)
NL (1) NL289045A (xx)
NO (1) NO118389B (xx)
SE (1) SE309457B (xx)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303538A (en) * 1962-04-17 1967-02-14 Mannesmann Ag Method for lowering a multiple cast ingot during continuous casting using only web contact
US3343593A (en) * 1964-12-29 1967-09-26 Electro Refractaire Process and apparatus for melting and solidifying continuously refractory materials
US4199343A (en) * 1977-08-29 1980-04-22 Corning Glass Works Mixing and injection molding hydrosilicates
US4674559A (en) * 1985-01-28 1987-06-23 Inresa Schultheiss Gmbh Continuous caster
US4719961A (en) * 1985-08-09 1988-01-19 Sms Schloemann-Siemag Aktiengesellschaft Vertical or bow-type continuous casting machine for steel
US20120174629A1 (en) * 2009-06-26 2012-07-12 Heraeus Quarzglas Gmbh & Co. Kg Method and device for drawing a quartz glass cylinder from a melt crucible

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1247028B (de) * 1964-01-23 1967-08-10 Swift Levick & Sons Ltd Dauermagnetlegierung
DE1198571B (de) * 1964-05-16 1965-08-12 Beteiligungs & Patentverw Gmbh Verfahren zur Herstellung anisotroper, kristallorientierter Dauermagnete aus einer Kobalt-Eisen-Nickel-Aluminium-Titan-Kupfer-Legierung
DE1219689B (de) * 1964-06-09 1966-06-23 Beteiligungs & Patentverw Gmbh Herstellung anisotroper, kristallorientierter Dauermagnete aus einer Kobalt-Eisen-Nickel-Aluminium-Kupfer-Legierung
SE445181B (sv) * 1982-12-15 1986-06-09 Nippon Light Metal Co Sett vid kontinuerlig metallgjutning
DE102009043462A1 (de) * 2009-09-30 2011-03-31 Vacuumschmelze Gmbh & Co. Kg Magnetischer Streifen, Sensor aufweisend einen magnetischen Streifen und Verfahren zur Herstellung eines magnetischen Streifens

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2135465A (en) * 1935-10-26 1938-11-01 Byron E Eldred Continuous casting of metal shapes
US2578407A (en) * 1948-01-10 1951-12-11 Gen Electric Method of making cast alnico magnets
GB743635A (en) * 1952-12-17 1956-01-18 Philips Electrical Ind Ltd Improvements in or relating to the manufacture of permanent magnets
CA531774A (en) * 1956-10-16 Continuous Metalcast Co. Method for the continuous casting of steel

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA531774A (en) * 1956-10-16 Continuous Metalcast Co. Method for the continuous casting of steel
US2135465A (en) * 1935-10-26 1938-11-01 Byron E Eldred Continuous casting of metal shapes
US2578407A (en) * 1948-01-10 1951-12-11 Gen Electric Method of making cast alnico magnets
GB743635A (en) * 1952-12-17 1956-01-18 Philips Electrical Ind Ltd Improvements in or relating to the manufacture of permanent magnets

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3303538A (en) * 1962-04-17 1967-02-14 Mannesmann Ag Method for lowering a multiple cast ingot during continuous casting using only web contact
US3343593A (en) * 1964-12-29 1967-09-26 Electro Refractaire Process and apparatus for melting and solidifying continuously refractory materials
US4199343A (en) * 1977-08-29 1980-04-22 Corning Glass Works Mixing and injection molding hydrosilicates
US4674559A (en) * 1985-01-28 1987-06-23 Inresa Schultheiss Gmbh Continuous caster
US4719961A (en) * 1985-08-09 1988-01-19 Sms Schloemann-Siemag Aktiengesellschaft Vertical or bow-type continuous casting machine for steel
US20120174629A1 (en) * 2009-06-26 2012-07-12 Heraeus Quarzglas Gmbh & Co. Kg Method and device for drawing a quartz glass cylinder from a melt crucible

Also Published As

Publication number Publication date
DE1433766A1 (de) 1969-10-30
SE309457B (xx) 1969-03-24
NL289045A (xx)
NO118389B (xx) 1969-12-22
CH461652A (de) 1968-08-31
CH365395A (de) 1962-11-15
GB1057904A (en) 1967-02-08
DK117444B (da) 1970-04-27
BE643866A (xx) 1964-08-14
DE1433766B2 (de) 1972-04-13
GB860127A (en) 1961-02-01

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