US3858136A - Apparatus for multipolar magnetization - Google Patents

Apparatus for multipolar magnetization Download PDF

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Publication number
US3858136A
US3858136A US00421948A US42194873A US3858136A US 3858136 A US3858136 A US 3858136A US 00421948 A US00421948 A US 00421948A US 42194873 A US42194873 A US 42194873A US 3858136 A US3858136 A US 3858136A
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Prior art keywords
sheet
gap
frequency
magnetic poles
poles
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US00421948A
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English (en)
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S Jun
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Yamauchi Rubber Industry Co Ltd
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Yamauchi Rubber Industry Co Ltd
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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

Definitions

  • ABSTRACT An apparatus comprises an annular magnetically per- [30] Forelgn Apphcatlon Pnomy Data meable main body having a width not smaller than the Dec. 7, 1972 Japan 47-123148 width of a sheet to be magnetized and formed with a small gap.
  • the magnetically permeable body has a [52] U.S. Cl. 335/284, 179/100.2 C conductor wound therearound and a pair of magnetic [51] Int. Cl. ..H01f13/00 poles opposing each other with the gap interposed Field Search 3 /2 1 1002 therebetween.
  • Alternating current is passed through 100.2 R, 17 9/1002 CF the conductor to magnetize the sheet for use in the manufacture of flexible permanent magnets which is [56] References Cited continuously travelled on the pair of magnetic poles.
  • the present invention relates to apparatuses for multipolar maggnetization for use in the manufacture of flexible permanent magnets, more particularly to a multipolar magnetizing apparatus for use in the manufacture of flexible permanent magnets in the form of an elongated sheet.
  • Such flexible permanent magnet is made by preparing an elongated sheet made of a mixture of synthetic rubber suchas styrene rubber, nitrile rubber, butyl rubber, neoprene rubber, isoprene rubber, ethylenepropylene rubber and chlorosulfonated polyethylene or synthetic resin such as vinyl chloride, polyethylene, chlorinated polyethylene and ethylene-vinyl acetate copolymer and a powdered magnetic material such as barium ferrite of l to 7 microns in the weight ratio of 1:5 to 10 and magnetizing the powdered magnetic material in the sheet. Since the flexible permanent magnet is in the form of a sheet, a great number of N poles and S poles must be arranged alternately. Multipolar magnetizing apparatuses have been developed to fulfil such requirement.
  • Apparatuses for multipolar magnetization heretofore known comprise a magnetically permeable body in the form of a flat plate having a great number of parallel grooves and a conductor fitted in the grooves in a zig-' zag manner.
  • a high voltage direct current is intermittently passed through the conductor to magnetize a sheet to be magnetized which is travelled intermittently in timed relation to the application of the current.
  • the conventional apparatus requires a power source of the charging and discharging type and is moreover inefficient inasmuch as it is not adapted for continuous magnetization. For efficient operation, therefore, there is a need to use a large magnetizing area and a high voltage source of several thousand volts, this rendering the apparatus costly and hazardous.
  • the present invention provides an apparatus for multipolar magnetization for use in the manufacture of flexible permanent magnets which has overcome the problems described above and which comprises an annular magnetically permeable body having a width not smaller than the width of a sheet to be magnetized and formed with a gap, a conductor wound around the magnetically permeable body and connected to an alternating current source to thereby pass constant exciting current of constant frequency therethrough and a pair of magnetic poles opposing each other with the gap which measures from I to 2.5 mm in size interposed therebetween and each having a surface to be positioned face-to-face with the sheet to be travelled continuously for magnetization.
  • the space between the magnetic poles to be formed in the sheet by magnetization can be readily varied by one of the following two methods. Firstly, the frequency is changed. Alternatively, the speed of travel of the sheet to be magnetized is changed. By altering the space between the magnetic poles formed by magnetization in the sheet of a given thickness the attracting force imparted to the magnetized sheet changes in accordance with the space between the magnetic poles. Thus to impart a maximum attracting force to the sheet of flexible permanent magnet, there is a need to set an optimum interpole space in corresponding relation to the thickness of the magnet. Generally, it is preferable that if the sheet of magnet has a large thickness, the interpole space be large, and a small interpole space for the sheet of a small thickness.
  • the space between the magnetic poles formed by magnetization can be varied continuously by the foregoing methods, so that it is easy to find by experiment an optimum interpole space in corresponding relation to the thickness of a sheet to be magnetized.
  • This makes it sure that sheets of flexible permanent magnet of varying thicknesses can be given the greatest attracting forces respectively by one multipolar magnetizing apparatus.
  • the present apparatus further assures an efficient operation inasmuch as the sheet to be magnetized is travelled continuously for magnetization.
  • the apparatus imparts uniform magnetism to the magnetized sheet to improve the quality of the product because it is easy to maintain the input at a uniform level. Since magnetization can be achieved with applications of a small current of low voltage, electric equipments for the apparatus are inexpensive and less hazardous.
  • the magnetizing poles can be positioned in register with each other easily, since the apparatus has only one pair of the poles, hence accurate magnetization.
  • FIG. I is a plan view showing a conventional multipolar magnetizing apparatus and a sheet while the sheet is being magnetized thereon;
  • FIG. 2 is a view in transverse section taken along the line II-II in FIG. 1;
  • FIG. 3 is a perspective view showing an embodiment of multipolar magnetizing apparatus according to this invention.
  • FIG. 4 is a perspective view showing another embodiment of this invention.
  • FIG. 5 is a fragmentary perspective view showing a modification of the embodiment of FIG. 3 in which the gap between a pair of magnetic poles is filled with synthetic resin;
  • FIG. 6 is a graph showing the relation between the frequency of alternating current used for magnetization and the attracting force of magnetized sheet
  • FIG. 7 is a graph showing the relation between the speed of travel of a sheet to be magnetized during magnetizing operation and the attracting force of magnetized sheet;
  • Hg. 8 is a graph showing the relation between the size of the gap between a pair of magnetic poles and the attracting force of magnetized sheet
  • FIG. 9 is a diagram showing the relation between the frequency of alternating current used for magnetization and the space between magnetic poles formed by magnetization and;
  • FIG. 10 is a diagram showing the relation between the speed of travel of a sheet to be magnetized and the space between magnetic poles formed by magnetization.
  • a conventional apparatus for multipolar magnetization comprises a platelike magnetically permeable body 2 formed with parallel grooves I in its upper surface, a conductor 3 fitted in the grooves l continuously in a zigzag manner and a greater number of magnetic poles 4 and 5 alternately arranged and formed between the grooves 1.
  • An elongated sheet 6 for use in the manufacture of flexible permanent magnets to be magnetized is made of a flexible material incorporating therein barium ferrite powder or like powder to be magnetized.
  • oneend portion of the sheet 6 is placed on the magnetizing apparatus and direct current is passed through the conductor 3, whereby magnetic poles are formed in the portions of the sheet 6 which portions are in contact with the'magnetic poles 4 and 5.
  • the magnetized area A1 of the sheet 6 corresponds to the surface area of the magnetizing apparatus.
  • FIG. 3 shows an embodiment of multipolar magnetizing apparatus according to this invention.
  • the apparatus includes a circular cylindrical magnetically permeable body 13 having a small gap 12 in its top.
  • the magnetically permeable body is made of parmalloy, but iron-nickel alloy, silicon steel, pure iron, carbon steel, nickel, cobalt and like material are also usable.
  • a sheet 11 for use in the manufacture of flexible permanent magnets to be magnetized is substantially the same as the sheet 6 described above.
  • the cylindrical, magnetically permeable body 13 has a width almost equal to that of the sheet 11. Of course, the body 13 must have a width not smaller than the width of the sheet 11 to be magnetized.
  • the cylinddrical, magnetically permeable body 13 is provided with a conductor 14 wound therearound and has a pair of magnetic poles l5 and 16 opposing each other with the gap 12 interposed therebetween.
  • the magnetic poles 15 and 16 have smooth upper surfaces 15a and 16a to be positioned face-toface with the sheet 11 to be magnetized.
  • the conductor 14 is connected to an alternating current source and thereby constant exciting current of constant frequency is continuously passed therethrough to magnetize the sheet 11 which is adapted to be travelled continuously in the direction of the arrow in FIG. 3 in facing relation to the pair of magnetic poles 15 and 16.
  • the magnetic poles 15 and 16 are tapered toward the portions where they oppose each other.
  • the opposing portions must not be sharp edges so as not to arrest the sheet 11.
  • the conductor 14 may be positioned closer to the magnetic poles 15 and 16 than is illustrated in the drawing, since the closer the conductor 14 is positioned to the magnetic poles l5 and 16, the lower will be the power required and the greater will be the magnetic flux to be produced.
  • FIG. 4 shows another embodiment of multipolar magnetizing apparatus according to this invention.
  • the apparatus includes an annular magnetically permeable body 23 having a substantially rectangular section and formed with a small gap 22 in its top.
  • a continuous conductor 24 is wound around the opposing walls of the magnetically permeable body 23.
  • Magnetic poles 25 and 26 have smooth upper surfaces 25a and 26a to be positioned face-to-face with a sheet to be magnetized and oppose each other with the gap 22 interposed therebetween.
  • FIG. 5 shows a modification of the multipolar magnetizing apparatus shown in FIG. 3 wherein the gap 12 is packed with synthetic resin 17.
  • the gap 12 is packed with synthetic resin 17.
  • the synthetic rein 17 packed in the gap 12 serves to obviate such objection.
  • FIG. 6 illustrates the relation between the frequency of alternating current applied to the multipolar magnetizing apparatus of FIG. 3 to carry out magnetizing operation and the attracting force of the magnetized sheet obtained.
  • the attracting force is plotted as ordinate and frequency as abscissa.
  • the size 1 of the gap 12 is 1 mm
  • the thickness of the sheet 11 to be magnetized is 0.6 mm
  • the speed of the sheet 11 travelled above the magnetic poles 15 and 16 is 8 m/min
  • the voltage of alternating current input is 200 V
  • the amperage of the same is 3 A.
  • the frequency of the input is varied with the result that an attracting force of about 40 g/2 cm is obtained at about 50 Hz as seen in FIG. 6.
  • FIG. 7 shows the relation between the speed of travel of the sheet to be magnetized and the attracting force of the sheet magnetized by the same apparatus as above.
  • the attracting force is plotted as ordinate and the speed of travel as abscissa.
  • the conditions are the same as in the case of FIG. 6 except that the frequency of the input is 50 Hz and the speed of travel is varied.
  • FIG. 7 indicates that a speed of travel of about 8 m/min gives a maximum attracting force of about 40 g/2 cm
  • FIG. 8 shows the relation between the size of gap of the same apparatus as above and the attracting force of the magnetized sheet.
  • the attracting force is plotted as ordinate vs. the gap size as abscissa.
  • the conditions are the same as in the case of FIG.
  • FIG. 8 reveals that the gap size ranging from I to 2.5 mm gives the greatest attracting force which is about 40 g/2 cm
  • FIGS. 6 to 8 indicate that the apparatus of this invention imparts an attracting force of about 40 g/2 cm to a sheet of 0.6 mm in thickness when it is magnetized. If a sheet has an attracting force of 30 g/2 cm the sheet is serviceable as a flexible permanent magnet for some uses. Although it has heretofore been necessary to increase the thickness of the flexible magnet sheet if it is desired to obtain a great attracting force, the present invention makes it possible for a thin sheet to have a high attracting force and therefore provides flexible magnets which are applicable to a wider variety of uses.
  • FIG. 9 shows the relation between the frequency of alternating current used for magnetization and the space between the magnetic poles formed by magnetization.
  • Current is plotted as ordinate vs. time as abscissa.
  • the sheet 11 to be magnetized is arranged in parallel to the abscissa to show the interpole space in corresponding relation to the frequency.
  • section Bl indicates magnetic poles obtained at a medium frequency, section B2 those obtained at a low frequency and section B3 those obtained at a high frequency. If the frequency is low, the space between the magnetic poles is large, whereas a high frequency gives a narrow interpole space.
  • FIG. 10 shows the variations in the space between the magnetic poles formed by magnetization using alternating current having a constant frequency and changing the speed-of travel of the sheet 11 to be magnetized.
  • section C1 indicates the result achieved at a medium speed of travel
  • section C2 that achieved at a high speed of travel
  • section C2 that achieved at a high speed of travel
  • section C3 that achieved at a low speed of travel.
  • a fast speed of travel produces an increased interpole space
  • a slow speed gives a narrow interpole space.
  • V P XfX 120 1,000 m/min.
  • An apparatus for multipolar magnetization for use in the manufacture of flexible permanent magnets comprising an annular, magnetically permeable body formed with a gap and having a width not smaller than the width of a sheet to be magnetized, a conductor wound around said body and connected to an alternating current source to thereby pass constant exciting current of constant frequency therethrough and a pair of magnetic poles opposing each other with said gap which measures from 1 to 2.5 mm in size interposed therebetween and each of said poles having a surface to be positioned face-to-face with said sheet as the sheet travels continuously thereover for magnetization.
  • An apparatus for multipolar magnetization for use in the continuous manufacture of flexible permanent magnets from a continuously moving sheet comprismg:
  • B a conductor which is wound around said body and is connected to a source of uninterrupted alternating current of constant frequency, amperage, and voltage.
  • the apparatus of claim 4 wherein said apparatus is capable of generating an attracting force of 40 g/2cm in said sheet when said gap is 1 mm in size, said frequency is 50 Hz, said voltage is 200 volts, said amperage is 3 amperes, and said sheet is formed of a flexible material incorporating barium ferrite powder therein, has a thickness of 0.6 mm, and travels at 8 meters per minute over said flat surfaces.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing Cores, Coils, And Magnets (AREA)
US00421948A 1972-12-07 1973-12-05 Apparatus for multipolar magnetization Expired - Lifetime US3858136A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP12314872A JPS56928B2 (de) 1972-12-07 1972-12-07

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US (1) US3858136A (de)
JP (1) JPS56928B2 (de)
CH (1) CH558587A (de)
DE (1) DE2361154A1 (de)
FR (1) FR2211731B1 (de)
GB (1) GB1406554A (de)
IT (1) IT1004654B (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4146956A (en) * 1976-04-09 1979-04-03 Tokyo Shibaura Electric Co., Ltd. Method for manufacturing a multipolar erasing head
US4237518A (en) * 1979-05-11 1980-12-02 Krulwich Lester S Nonelectric magnetizer and demagnetizer
US5515020A (en) * 1991-08-14 1996-05-07 Icl Systems Aktiebolag Premagnetizing head
US6822827B1 (en) * 2001-06-07 2004-11-23 Imation Corp. Erasure techniques for magnetic tape media
US20090134963A1 (en) * 2007-11-26 2009-05-28 Ogden Jr Orval D Flexible magnetic sheet systems
US8893955B2 (en) 2010-10-27 2014-11-25 Intercontinental Great Brands Llc Releasably closable product accommodating package

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5928043B2 (ja) * 1976-01-16 1984-07-10 日立金属株式会社 永久磁石の微小間隔着磁装置
DE2814392C2 (de) * 1977-04-13 1983-10-27 Evva-Werk Spezialerzeugung von Zylinder- und Sicherheitsschlössern GmbH & Co KG, 1120 Wien Oberflächenmagnetisierungsvorrichtung
DE19831415A1 (de) * 1998-04-17 1999-10-21 Meto International Gmbh Vorrichtung zum Deaktivieren eines Sicherungselementes für die elektronische Artikelsicherung
JP4018313B2 (ja) * 2000-03-01 2007-12-05 Ｎｔｎ株式会社 磁気エンコーダの製造方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2711945A (en) * 1953-03-04 1955-06-28 Clevite Corp Magnetic transducer head for high frequency signals
US2715659A (en) * 1950-10-14 1955-08-16 Ibuka Masaru Magnetic heads for magnetic recording and reproducing apparatus
US2939920A (en) * 1953-12-28 1960-06-07 Stifterverband Fur Die Deutsch Magnetic heads for recording and reproducing signals
US3140361A (en) * 1960-12-30 1964-07-07 Ampex Magnetic head assembly

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2715659A (en) * 1950-10-14 1955-08-16 Ibuka Masaru Magnetic heads for magnetic recording and reproducing apparatus
US2711945A (en) * 1953-03-04 1955-06-28 Clevite Corp Magnetic transducer head for high frequency signals
US2939920A (en) * 1953-12-28 1960-06-07 Stifterverband Fur Die Deutsch Magnetic heads for recording and reproducing signals
US3140361A (en) * 1960-12-30 1964-07-07 Ampex Magnetic head assembly

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4146956A (en) * 1976-04-09 1979-04-03 Tokyo Shibaura Electric Co., Ltd. Method for manufacturing a multipolar erasing head
US4237518A (en) * 1979-05-11 1980-12-02 Krulwich Lester S Nonelectric magnetizer and demagnetizer
US5515020A (en) * 1991-08-14 1996-05-07 Icl Systems Aktiebolag Premagnetizing head
US6822827B1 (en) * 2001-06-07 2004-11-23 Imation Corp. Erasure techniques for magnetic tape media
US20090134963A1 (en) * 2007-11-26 2009-05-28 Ogden Jr Orval D Flexible magnetic sheet systems
AU2008329884B2 (en) * 2007-11-26 2013-07-04 Magnum Magnetics Corporation Flexible magnetic sheet systems
EP2222458B1 (de) * 2007-11-26 2018-08-29 Magnum Magnetics Corp. Systeme für flexible magnetische flächengebilde
US8893955B2 (en) 2010-10-27 2014-11-25 Intercontinental Great Brands Llc Releasably closable product accommodating package

Also Published As

Publication number Publication date
IT1004654B (it) 1976-07-20
CH558587A (de) 1975-01-31
JPS56928B2 (de) 1981-01-10
DE2361154A1 (de) 1974-06-12
FR2211731A1 (de) 1974-07-19
JPS4978899A (de) 1974-07-30
GB1406554A (en) 1975-09-17
FR2211731B1 (de) 1978-02-10

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