US3887401A - Magnetic parts and method of manufacturing same - Google Patents

Magnetic parts and method of manufacturing same Download PDF

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Publication number
US3887401A
US3887401A US351324A US35132473A US3887401A US 3887401 A US3887401 A US 3887401A US 351324 A US351324 A US 351324A US 35132473 A US35132473 A US 35132473A US 3887401 A US3887401 A US 3887401A
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Prior art keywords
parts
interval
temperature
magnetic
maintaining
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US351324A
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English (en)
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Max Hetzel
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SSIH Management Services SA
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SSIH Management Services SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F13/00—Apparatus or processes for magnetising or demagnetising
    • H01F13/003—Methods and devices for magnetising permanent magnets
    • G—PHYSICS
    • G04—HOROLOGY
    • G04C—ELECTROMECHANICAL CLOCKS OR WATCHES
    • G04C3/00—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means
    • G04C3/08—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a mechanical oscillator other than a pendulum or balance, e.g. by a tuning fork, e.g. electrostatically
    • G04C3/10—Electromechanical clocks or watches independent of other time-pieces and in which the movement is maintained by electric means wherein movement is regulated by a mechanical oscillator other than a pendulum or balance, e.g. by a tuning fork, e.g. electrostatically driven by electromagnetic means
    • G—PHYSICS
    • G04—HOROLOGY
    • G04D—APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES
    • G04D9/00—Demagnetising devices

Definitions

  • ABSTRACT Extremely small parts are made free of rest magnetization by heating them in a gas oven at a first temperature above the Curie temperature. The parts are then cooled to a second temperature and maintained at the second temperature over a interval of time before being cooled to room temperature.
  • the gas oven may include means for applying an alternating magnetic field of decreasing magnitude to the parts while the parts are at the first temperature. The method results in extremely small parts which are completely free of rest magnetization.
  • the parts which may be discs, may then be magnetized around their periphery with succeeding poles of opposite polarity. to thus provide magnetic couplings or gears suitable for use in watches.
  • the invention refers to a method of manufacturing magnetic parts, particularly small magnetic coupling discs.
  • the manufacture of some magnetic parts requires relatively complicated demagnetization procedures. Such a demagnetization is required if, for instance, the part must later on be provided with a certain specific magnetic pattern.
  • the mechanical, chemical or electrochemical processes, such as stamping, cutting, rolling, electroerosion, etc. that are used in forming the magnetic parts cause in the magnetizable materials a rest (remanent) magnetization, or a certain material structure.
  • this rest magnetization can be a disadvantage or troublesome influence.
  • the strength of the rest magnetization after form ing is further dependent on the influences of foreign magnetic fields and is a function of the magnetic hardness of the material used. Accordingly, the problem of rest magnetization is closely related to the selection of the material and the respective manufacturing methods.
  • An object of the present invention is to provide a method of practically completely demagnetizing extremely small and sensitive parts made of ferromagnetic materials, particularly alloys. It is further an object of the invention to provide a means for carrying out the inventive method on small ductile magnetic parts.
  • this is obtained by first forming the parts and then freeing them of their rest magnetization by a process including the steps of a first heat treatment at high temperature in a gas oven, then after a short intermediate phase, subjecting the parts to a second heat treatment at a lower temperature, and then slowly cooling the parts to room temperature, so
  • the demagnetized parts can be provided with a desired pattern of magnetization.
  • a gas oven to carry out said method is characterized in that the interior thereof is practically completely free of any magnetic fields and comprises a device for building up an alternating magnetic field of adjustable field strength.
  • Said field strength is preferably on the order of approximately-50 Oersted at the upper limit.
  • the invention relates also to extremely small discs of ductile material manufactured according to said method and characterized in that they comprise at their periphery a number of small magnetic teeth of different directions of magnetization. That is, the discs have around their periphery small magnetic poles, adjacent poles being of alternate polarity.
  • FIG. 1 shows schematically a gas oven
  • FIG. 2 shows a typical magnetic part in highly enlarged scale
  • FIG. 3 shows the sequence of the heat treatment in the form of a diagram
  • FIG. 4 shows schematically the oscillogram of an external demagnetization field applied to the parts to be dernagnetized.
  • the magnetic disc 1 is provided in the final stage of manufactur ng with a plurality of north and south poles located alternatingly at the periphery of the disc toprovide a kind of small magnetic teeth 3.
  • Such discs can be used as coupling gears for touchless couplings, where friction or sealing problems have to be considered in the transmission of forces.
  • the material used in the disc must be ductile.
  • a platinum cobalt alloy may be used, preferably an alloy consisting of approximately 75 percent by weight platinum and 25 percent by weight cobalt.
  • the method basically comprises the following steps. After the discs 1 or other parts (FIG. 1) are formed by any suitable method, they are freed from their still existing rest magnetism, or the rest magnetism caused by manufacturing or foreign fields. As FIG. 3 shows, this is accomplished by a first heat treatment 7 at a demagnetizing temperature T substantially above the Curie point of the alloy.
  • the demagnetizing temperature T is preferably l 150C.
  • the magnetic parts 5 are kept at the demagnetization temperature T for a period of time t of approximately 20 minutes.
  • the interior ll of the oven used for heat treatment be practically free of any field.
  • the own field of the oven should not exceed 5 Oersted, because otherwise this field is frozen into the magnetic parts.
  • an oven is used which is not electrically heated.
  • an oven 13 is used, which is designed to meet the special requirements described. Such an oven will be described in detail later on.
  • an additional demagnetization 9 can be applied.
  • the magnetic parts 5 in the interior 11 of the gas oven 13 are subjected to a subsiding magnetic alternating field 15 (FIG. 4).
  • the field curve of the alternating field 15 can be of the form shown in FIG. 4.
  • the field strength H is brought to a maximum value I-Im which causes a coercitive value in the magnetizable parts which is safely above the value of the expected rest magnetization.
  • the field has a value of approximately 50 Oersted.
  • the duration of the demagnetization 19 is preferably 2 to 5 seconds.
  • the alternating field 15 is generated in the gas oven 13 by the device schematically shown in FIG. 1.
  • a coil 21 encloses the whole interior ll of the gas oven 13 and is in electric connection with an alternating voltage control device 23 which may be simply a variable transformer (Variac) connected to the power mains.
  • Variac variable transformer
  • By setting the variable transformer any desirable amplitude value of the voltage and therefore any magnetic field of the coil 21 up to a maximum value (for instance H and corresponding voltage) can be selected to obtain the field curve shown in FIG. 4.
  • the temperature of the gas oven 13 is rapidly lowered during an intermediate phase 25 from the value T to the value of the second heat treatment 27. This change of temperature must take place during a transit time t of approximately 3 minutes.
  • the annealing temperature T is used for the following second heat treatment 27.
  • the magnetic characteristics e. g., the form of the hysteresis loop
  • the annealing temperature T is above the Curie point.
  • the annealing temperature T is set for the described discs of platinum cobalt alloy at 650C and maintained during the annealing time t of approximately 1 hour.
  • the magnetic parts are in a magnetically virgin state with defined hysteresis characteristics and ready for further treatment.
  • the parts 5 can now be magnetized by exposing them to suitable magnetic fields according to the requirements dictated by their intended use.
  • the discs 1 are located in special magnetic coils and are magnetized at their periphery according to the desired pattern by means of surge currents.
  • the magnetic discs 1 can have the form as discs or wheels provided with spokes. They may be fiat at the periphery or may be provided with teeth. The discs may be used in magnetic couplings for very small torques or in small gear drives where they can also have the function of a gear.
  • the described method for manufacturing magnetic parts is based on a gas oven 13 which may be of known design, but must have an interior 11 that is practically completely free of any magnetic fields. This can be obtained by using suitable antimagnetic materials for the design of the oven, the location of the oven at a place free of magnetic fields, or by an effective shielding. Further, the gas oven 13 may be provided with a coil 21 with which the whole interior 11 of the oven can be provided with an uniform demagnetization field.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Hard Magnetic Materials (AREA)
  • Soft Magnetic Materials (AREA)
US351324A 1972-05-05 1973-04-16 Magnetic parts and method of manufacturing same Expired - Lifetime US3887401A (en)

Applications Claiming Priority (1)

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CH674172 1972-05-05

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JP (1) JPS4954898A (ja)
CH (2) CH545530A (ja)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4036753A (en) * 1975-07-18 1977-07-19 Ngk Insulators, Ltd. Pyrolysis process for treating sewage sludge containing chromium
US4265680A (en) * 1980-03-10 1981-05-05 Astrolab Corp. Method for making hollow magnetic pipe
US5366566A (en) * 1989-10-13 1994-11-22 Centre National De La Recherche Scientifique Method for preparing a very high quality magnetic material
US5935346A (en) * 1997-06-04 1999-08-10 Mecagis Process for the heat treatment, in a magnetic field, of a component made of a soft magnetic material
US6217672B1 (en) * 1997-09-24 2001-04-17 Yide Zhang Magnetic annealing of magnetic alloys in a dynamic magnetic field
US20030215351A1 (en) * 2002-05-15 2003-11-20 Steven Kretchmer Magnetic platinum alloys
US20050273999A1 (en) * 2004-06-09 2005-12-15 General Electric Company Method and system for fabricating components
CN109741902A (zh) * 2019-01-08 2019-05-10 苏州腾凯金属材料有限公司 一种电磁阀的去磁方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112904699B (zh) * 2021-03-02 2022-11-04 上海科世达-华阳汽车电器有限公司 一种汽车peps系统及其消磁控制方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1708936A (en) * 1926-12-23 1929-04-16 Bell Telephone Labor Inc Magnetic material
US2307605A (en) * 1938-09-21 1943-01-05 Gen Electric Magnetic material heat treatment
US2504870A (en) * 1947-02-07 1950-04-18 Jessop William & Sons Ltd Method of manufacturing permanent magnets
US2622050A (en) * 1951-03-22 1952-12-16 Gen Electric Process for heat-treating cobalt-platinum magnets
US2765161A (en) * 1952-06-03 1956-10-02 William Mungall Jig for selective hardening of steel rings
US2837452A (en) * 1955-01-19 1958-06-03 Philips Corp Method of making anisotropic permanent magnets
US2933427A (en) * 1956-03-28 1960-04-19 Philips Corp Permanent anisotropic magnet and method of making same

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1708936A (en) * 1926-12-23 1929-04-16 Bell Telephone Labor Inc Magnetic material
US2307605A (en) * 1938-09-21 1943-01-05 Gen Electric Magnetic material heat treatment
US2504870A (en) * 1947-02-07 1950-04-18 Jessop William & Sons Ltd Method of manufacturing permanent magnets
US2622050A (en) * 1951-03-22 1952-12-16 Gen Electric Process for heat-treating cobalt-platinum magnets
US2765161A (en) * 1952-06-03 1956-10-02 William Mungall Jig for selective hardening of steel rings
US2837452A (en) * 1955-01-19 1958-06-03 Philips Corp Method of making anisotropic permanent magnets
US2933427A (en) * 1956-03-28 1960-04-19 Philips Corp Permanent anisotropic magnet and method of making same

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4036753A (en) * 1975-07-18 1977-07-19 Ngk Insulators, Ltd. Pyrolysis process for treating sewage sludge containing chromium
US4265680A (en) * 1980-03-10 1981-05-05 Astrolab Corp. Method for making hollow magnetic pipe
US5366566A (en) * 1989-10-13 1994-11-22 Centre National De La Recherche Scientifique Method for preparing a very high quality magnetic material
US5935346A (en) * 1997-06-04 1999-08-10 Mecagis Process for the heat treatment, in a magnetic field, of a component made of a soft magnetic material
AU733279B2 (en) * 1997-06-04 2001-05-10 Mecagis Process for the heat treatment, in a magnetic field, of a component made of a soft magnetic material
CN1112711C (zh) * 1997-06-04 2003-06-25 梅加日公司 软磁材料制成的元件的磁场热处理工艺
US6217672B1 (en) * 1997-09-24 2001-04-17 Yide Zhang Magnetic annealing of magnetic alloys in a dynamic magnetic field
US20030215351A1 (en) * 2002-05-15 2003-11-20 Steven Kretchmer Magnetic platinum alloys
US6869567B2 (en) * 2002-05-15 2005-03-22 Steven Kretchmer Magnetic platinum alloys
US20050273999A1 (en) * 2004-06-09 2005-12-15 General Electric Company Method and system for fabricating components
CN109741902A (zh) * 2019-01-08 2019-05-10 苏州腾凯金属材料有限公司 一种电磁阀的去磁方法

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Publication number Publication date
JPS4954898A (ja) 1974-05-28
CH674172A4 (ja) 1973-08-31
CH545530A (ja) 1974-01-31

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