Showing papers on "Magnetic core published in 1984"

Determination of AC magnetic power loss of electrical steel sheet: Present status and trends

Abstract: A brief survey of the status of work in the higher induction and frequency ranges is given and recent papers on the measurement of rotational losses are reviewed. The determination of the magnetic losses in alternating fields is considered, in partucular regarding the performance of those magnetic circuits most widely used in loss measurements. New and revised data contribute to the elucidation of the systematic errors of the Epstein square. The Epstein samples and plate samples, both of various materials, were used for measurements with single sheet testers, whereby the field strength was determined both from the magnetizing current by means of a precision resistor and direct, using field sensing coils. From these results conclusions for the appropriate value of the effective magnetic path length can be drawn. The electric power measurement particularly as regards digital procedures, calibration and uncertainties is briefly discussed.

Nuclear magnetic resonance apparatus

Abstract: A nuclear magnetic resonance apparatus comprises an electromagnetic system in which a shield of a magnetic material is arranged about the coil system for the homogeneous magnetic field. By providing the magnetic material, for example soft iron, directly about the coil system, a comparatively compact magnetic with an intensified, interference-insensitive homogeneous magnetic field is obtained. Instead of using a closed cylinder, use can alternatively be made of a cylinder which is formed by rods. The latter is notably attractive for shielding at a larger distance, the original field in the coil then being influenced to only a minor extent. A similar shielding can be obtained by means of a Helmholtz coil pair.

Effects of coatings on the soft magnetic properties of an iron-based amorphous alloy

Abstract: Measurements of core loss and de magnetic properties are reported on insulated and uninsulated smooth, high pack-factor iron-based amorphous metal ribbon. Higher losses measured on uninsulated ribbons, wound with winding tensions of 5 N and above, are found to be associated with macroscopic interlaminar eddy currents due to numerous shorts between laminations.

Magnetic head comprising a core formed of small and large thin film patterns

Abstract: A thin film magnetic head comprising a magnetic core of accumulation layers forming a magnetic circuit and including at least two layers of magnetic film with a particular magnetic characteristic. The constitution of completely covering a magnetic film with a small pattern by a magnetic film with a large pattern makes the edge part smooth because the end of the underlying magnetic film is covered with the upper magnetic film. This edge-smoothing effect appears most pronounced in a manufacturing method in which electrodeposition is used for the formation of magnetic films. By sequentially forming the magnetic films from that of a smaller pattern towards that of a larger pattern, the film formation proceeds at step parts such as end parts of the underlying magnetic films due to the levelling action which is inherent in the electrodeposition method. Such a film formation realizes extremely smooth shielding and yet the pattern formation can be carried out by a single step of photoresist coating to shorten the production process.

Iron core for electrical machinery and apparatus as well as method for producing the iron core

Abstract: For the iron cores of an electrical machinery and apparatuses, such as transformers, electric motors and generators, mostly a grain-oriented electromagnetic steel sheet is used. Since the grain-oriented electromagnetic steel sheet has a (110) [001]texture and is thus easily magnetized in the rolling direction, the direction of magnetic flux in the iron cores is required to be coincident with the rolling direction. However, this requirement cannot be completely fulfilled due to the shape and an operation efficiency of producing the iron cores as well as generation of a magnetic reluctance in the butted iron-core elements. Laser irradiation regions are formed, according to the present invention, for example, on the following: the parts of the iron core where the rotational magnetic field is generated; the entire surface of the I-type elements or: the major part of the E or C type element. As a result of the laser-irradiation, the watt loss is low even where the complete coincidence of the easy direction of magnetization and the magnetic flux direction is difficult.

Core element for electrodynamic rotary machine

Abstract: An improved magnetic core element for use in an electrodynamic rotary machine, and the method of making such a core element are disclosed. The core element, either a stator or rotor depending upon the design of the machine, is provided with a slot distribution such that when the rotor rotates with respect to the stator and a balanced energy field is provided therebetween, at least the lowest generated harmonics, will be substantially zero.

Residual current circuit breaker

Abstract: A sensor device for a residual current circuit breaker has a magnetic core (1) on which portions of respective conductors (3, 4) carrying current to and from a load are wound, and a Hall Effect element (2) located in an air gap in the core for producing an output signal dependent upon the resultant flux intensity induced in the core. The circuit breaker includes a signal processor (16) controlling actuation of a tripping solenoid (11) to open contacts (RC1, RC2) to interrupt supply of electric power to a load (10) when the currents flowing in the respective conductors (3, 4) differ by more than a given amount.

Magnetic head for effecting perpendicular magnetic recording

Abstract: In a magnetic head for perpendicular magnetization recording of a main magnetic pole exited type, a high permeability magnetic thin layer is held at its top portion by nonmagnetic supporter and the thin layer is closed by a first high permeability block. The thus constructed main magnetic pole is surrounded by a second high permeability block, and a third high permeability block is located in facing relation to the main magnetic pole and second high permeability material. This magnetic head has high recording and reproducing efficiency and well-shielded from external magnetic field. Some structural improvements are also provided so that leakage of magnetic flux, disconnection and short circuit of a coil are avoided.

Magnetic recording device

Abstract: PURPOSE:To save electric power and solve the problem of heat generation by using a self-holding type solenoid which is only fed with an instantaneous current at head loading, i.e. at attraction and return and requires no holding current. CONSTITUTION:The solenoid has a compression coiled spring 10 which generates restoring force and a permanent magnet 5 at the front part. A figure (a) shows a state before an attracting coil 1 is conducted. When the gap 13 between a movable iron core 3 and a fixed receptacle 9 is set larger than the gap 12 between the movable iron core 3 and a yoke 7, almost no attracting force is generated at the gap 13 by the magnetic force of the permanent magnet 5. A figure (b) shows an conductive state and the magnetic flux by the coil 1 is opposite to the magnetic flux of the permanent magnet 5 at the gap 12, so that all pieces of magnetic flux are attracted by the fixed receptacle 9. A figure (c) shows the nonconductive state of the coil 1 after the movable iron core 3 is attracted to the fixed receptacle 9 and the gap 13 at this time is zero, so the movable iron core 3 and fixed receptacle 9 are attracted continuously by the magnetic flux of the permanent magnet 5. A figure (d) shows a state when the conductive direction is made opposite, and the iron cre returns to its original position by the compressed coiled spring 10.

Magnetizing Current, Iron Losses And Forces Of Three-Phase Induction Machines At Sinusoidal And Nonsinusoidal Terminal Voltages. Part I: Analysis

Abstract: Currents, losses, winding and iron core forces at no-load of saturated three-phase induction machines are determined based on a nonlinear magnetic field analysis. Instantaneous magnetizing currents are calculated for given balanced sinusoidal and nonsinusoidald- terminal voltages. Subsequently, the harmonic components of the magnetizing current and the induced voltage are obtained from a Fourier analysis. The coreloss- current component is derived from the sum of local core losses and the no-load current is then iteratively obtained from the sum of the magnetizing and the coreloss- current components. Finally, the calculation of winding and iron-core forces is derived from surface integrals. Part II deals with the results that are based on this analysis.

Magnetic head having an integrated recording and playback head and an erasure head

Abstract: The present invention relates to a magnetic head, which can form guard bands on a magnetic recording medium and which is especially suitable for magnetic discs, and a fabrication process thereof. The magnetic core of the present invention includes a recording and reproduction head core (31) and an erasure head core (32) which is integrally joined in series to the head core (31) for forming guard bands. Magnetic circuits are constructed of metallic magnetic materials (34), (34'), (35) and (35') formed on non-magnetic members (33) and (33'). As a result, a recording medium having high coercive forces can be recorded while the track width is reduced and the fabrication is facilitated with a high accuracy.

Device for measuring, without contact, the thickness of metallic materials at temperatures above the Curie temperature

Abstract: The sensor is constituted by a magnetic core with pole pieces and by an electric coil wound on the body of said core. With said coil there are associated a sinusoidal current generator and impedance measurement means. A processor determines the thickness from the measured value of said impedance.

Magnetic resonance-type playback apparatus including a magnetic material having magnetic anisotropy

Abstract: A magnetic playback apparatus using ferromagnetic resonance of a magnetic material provided with a magnetic anisotropy to develop an anisotropic magnetic field. The magnetic material is disposed at a position influenced by a magnetic field resulting from a signal recorded on the magnetic recording medium. The magnetic material is coupled with a high frequency circuit to be supplied with a high frequency magnetic field. The high frequency characteristics of the magnetic material greatly vary depending on a ferromagnetic resonance. A ferromagnetic resonance magnetic field is set up, allowing for the magnitude of an anisotropic magnetic field and the frequency of the high frequency magnetic field, so that a great variation in the high frequency characteristics due to the ferromagnetic resonance may be obtained according to the signal magnetic field.

Apparatus for detecting ultrasonic vibration

Abstract: This invention is an apparatus for detecting the vibration of a Langevin type electrostrictive ultrasonic vibrator comprising a system made up of an iron core, a coil and a magnet surrounding but not connected to a magnetic projection attached to the rear end of the vibrator. The vibration of the magnetic projection is detected by the system surrounding it and the resulting induced voltage is fed back to a control to maintain the vibration at the desired resonant frequency.

Multi channel magnetic transducer head

Abstract: A multi channel magnetic transducer head comprises a magnetic substrate, and a plurality of thin film type magnetic transducer head elements arranged on the magnetic substrate, each magnetic transducer head element including a coil conductor disposed on the magnetic substrate and a thin film magnetic core to constitute a magnetic circuit in co-operation with the substrate, wherein a non-magnetic gap spacer layer with a predetermined thickness is formed at track width portion below front end of the thin film magnetic core on the magnetic core, a non-magnetic layer with thickness larger than that of the gap spacer layer is formed at track spacing portion, the thin film magnetic core has width covering at least the gap spacer layer of the track width portion, thereby good magnetic recording can be performed.

Improvement of magnetic properties in thinner HI-B with domain-refinement

Abstract: The domain-refinement technique which was developed to decrease anomalous eddy-current loss showed remarkable effect. The LASER-scribing method enabled the development of industrial products. Moreover, when this domain-refinement was applied to thinner gaged core material, the effect appeared in a marked degree. In this paper, the improvement of magnetic Properties of 0.23mm thick domain-refined core material is emphasized, because it has been used widely. It was clarifyed that the effect of domain-refinement depended on the thickness of core materials and the induction at 1000A/m strongly. The core losses, 0.80W/kg at 1.7T, 50Hz and 0.59W/kg at 1.5T, 50Hz were successfully obtained for an industrial product, 0.23mm HI-B. When the LASER-scribing was applied to very high permeability HI-B, the hysteresis loss was little changed, but the eddy-current loss decreased sharply. Further, by the numerical analysis with actually measured data, the Building Factor was also improved by the patterns of the LASER-scribing.

A design study of amorphous core transformer

Abstract: The characteristics of large amorphous core transformers, such as %IZ, core loss and load loss, are discussed in design examples considering the properties of core materials. Some desings of 5000 kVA transformers with amorphous cores are compared with Si-steel core transformers, and the measured characteristixs of a 100 kVA trial transformer are described. The core losses of the composite amorphous and Si-steel cores are also described.

Method and apparatus for electrically detonating blasting primers

Abstract: A number of detonating primers are electrically blasted by supplying a high frequency current through a bus wire formed by a pair of parallel conductors connected to each other at distal ends and having a constant impedance with which bus wire loops connected to the detonating primers via leg wires are electromagnetically coupled via a number of magnetic cores having slits formed therein. At first, one or more loops are inserted into respective magnetic core through the slit and one of the parallel conductors is also inserted into the magnetic core through the slit. When the high frequency current having a frequency from 100 KHz to 1 MHz is passed through the conductors of bus wire in opposite directions, there is induce electromagnetically secondary high frequency currents in respective loops, which are supplied to respective detonating primers for explosion.

Method of manufacturing a turnable microinductor

Abstract: A microcoil having a winding on a composite core made up of a portion of substantially magnetic material and a portion of substantially non-magnetic material. The winding is split so that a part of the magnetic material core portion is exposed, and a laser is used to remove material from the exposed part of the magnetic core portion. The inductance of the coil is measured during the removal of the magnetic material, and the inductance of the coil is trimmed to a desired value through the removal of an appropriate amount of magnetic material. The non-magnetic core portion serves as a support structure for the portions of the winding on the core even if a substantial portion of the magnetic material is removed.

Gas solenoid valve

Abstract: A gas solenoid valve comprising a magnetic circuit formed with a fixed iron core, magnets and a magnetic member; a coil-holder movably provided with respect to the outer periphery of the fixed iron core and having a magnetic coil wound around itself; a sleeve accommodated within the magnets and spaced apart from the outer periphery of the fixed iron core for a predetermined distance; an actuating portion formed with the fixed iron core; the fixed iron core, the magnets and a magnetic member all fixedly covered with a molding resin from outside; and a governing portion engaged with the actuating portion.

Magnetic transducer head having an alloy thin film of high saturation magnetic flux density slantly provided with respect to an operating magnetic gap formed therein

Abstract: A magnetic transducer head comprising a first magnetic core element and a second magnetic core element, each of the first and second core elements comprising a magnetic ferrite block and a magnetic metal thin film integrated with the magnetic ferrite block. These core elements having a first planar surface and a second planar surface. The magnetic metal thin film being provided on the second planar surface and having an edge thereof facing to the first planar surface, and the second planar surface being slantly provided with respect to said first planar surface. These core elements being bonded together to form an operating magnetic gap between the edge of the magnetic metal thin film on the first core element and the edge of the magnetic metal thin film on the second core element. The magnetic metal thin film on the first core element or the magnetic thin film on the second core element is formed in one common plane. The magnetic metal thin film may be formed of the ferromagnetic metals including Fe--Al--Si alloys, amorphous metal alloys or permalloy. And the magnetic metal thin film having substantially uniform columnar grain structure or uniform magnetic anisotropy, over entire area of the film.

Distributed pulse forming network for magnetic modulator

Abstract: A pulse forming network with distributed inductance and capacitance is diosed for use in a magnetic modulator. The magnetic modulator has a magnetic core with a primary winding and a secondary winding around it. The pulse forming network includes an inner winding of flattened wire around the magnetic core and connected to one end of the secondary winding for receiving an induced voltage. The pulse forming network also includes a metal foil shield around the inner winding, so that the induced voltage may be stored capacitively between the inner winding and the shield. When the magnetic core saturates, the impedance of the secondary winding drops, so that the pulse forming network discharges through a load. The shape of the pulse through the load is determined by the inductance of the inner winding and the capacitance between the inner winding and the shield. The number of turns per unit length of the inner winding, the spacing between the inner winding and the shield, and the dielectric constant of an insulating layer of material between the inner winding and the shield may all be modified to obtain a pulse forming network forming a desired pulse shape.

Amorphous magnetic material having excellent magnetic characteristics

Abstract: PURPOSE:To obtain excellent magnetic characteristics by a method wherein the surface configuration of the amorphous material to be used for magnetic core is limited. CONSTITUTION:It is necessary that a strip-formed wave possesses the conditions given by the below-mentioned formula when its intensity is Rf, its pitch is P(mm.) and the plate thickness of material is (t)(mm.) in order to lower the degree of effect of the stripe- formed wave and to reduce an eddy current loss. The formula is 1X10 )/ (0.5+Rf) . Further, (Pt )/(0.5+Rf) indicates the degree of effect of the stripe- formed wave given to an eddy current loss. Besides, if a high magnetic density is required, the relation between the degree of roughness of the surface, whereon a stripe- formed wave is generated, and the plate thickness is to be brought to 2X10 or below in Rl/t. At this point, Rl indicates the degree of roughness of the surface. In order to generate the above-mentioned stripe-formed wave, the melt pouring is to be performed in the temperature range of approximately 1,270-1,300 deg.C, thereby enabling to increase Rf and to decrease Rl. The optimum Rf and Rl can be selected by the melt pouring temperature as above-mentioned, and the product of low iron loss and high magnetic flux density can be accomplished.

Iron powder core magnetic device

Abstract: A compacted powdered iron core utilizes iron powder in the 0.002 to 0.006 mean particle size range which is first coated with an alkali metal silicate and then overcoated with a silicone resin polymer. The treated powder is compressed to approximately 94% of theoretical density and then annealed at approximately 600 DEG C. This results in a core component characterized by overall core losses as low as in conventional laminated cores in A.C. operation.

Manufacture of magnetic core

Abstract: PURPOSE:To obtain the magnetic core having low degree of deterioration to accompany with the work performed by a method wherein the cut face o the magnetic core is polished while the cut face is being sucked by a vacuum pump when a cutting work is performed on the magnetic core. CONSTITUTION:A number of small holes are provided on a polishing paper 2, and the lower surface of the polishing paper is supported by the vessel 4 which is decompressed by a vacuum pump 3. Therefore, when a polishing work is performed by contacting the magnetic core 1 to the polishing paper 2, the burrs and broken pieces generating when the polishing work is performed are absorbed toward the lower part of the vessel 4 as shown by the arrows in the diagram. As a result, the cut surface having no foreign matters between the burrs and the layer can be obtained, and the magnetic characteristics (iron loss value) can be recovered to the condition before cutting.

Bonding method of magnetic head

Abstract: PURPOSE:To prevent output loss by providing a cut slot to a base surface of a magnetic head of a rotary head VTR, applying an adhesives between a base surface and a magnetic core through the cut slot and bonding them so as to be fixed with a bonding layer with uniform thickness. CONSTITUTION:A cut slot 15 having a depth of nearly 50mum is provided to a face A of a base 1 (shown expandedly as caption 14 in Fig. 14) provided with a hole 7 and a cut slot 8 to fit magnetic heads 2, 3 of a VTR to a rotary cylinder while being butted onto the face A of the base 1, a magnetic core 18 having a large area of a head 2 (caption 17 in Fig.) is placed on the slot 15, a heat softening epoxy resin 16 or the like is applied to a point between the slot 15 and the core 18, the assembly is heated in a constant temperature furnace so as to impregnate the resin between the base and the core 18. Thus, the resin 16 is fixed while being made to a thin and uniform layer. Thus, both heads 2, 3 are bonded to the base 1 with high accuracy so as to prevent the output loss or the like.

Composite magnetic head

Abstract: PURPOSE:To attain recording/reproduction with very high density and to prevent mutual interference of magnetic flux, by providing a notch for both of a write/ read gap and an erase gap and separating a write/read magnetic head core from an erase magnetic head core with a nonmagnetic layer. CONSTITUTION:The 1st magnetic head core 21 and the 2nd magnetic core 22 have the same thickness as a couple and a write/read gap 23 made of a nonmagnetic substance is formed between opposing surfaces of the cores 21, 22. The same 1st notch 24 is formed on both sides of the gap 23, i.e., at both sides of the cores 21, 22 respectively and the width of the gap 23 is limited to a value Tw with the 1st notches 24. In recording signals on a medium with the magnetic head, the magnetic head is slided on the medium and the recording is done over the width Tw of the gap 23 with a write/read magnetic head core 26. Immediately after the recording, recorded both ends of the width Tw are erased with an erase magnetic head core 36 following to the core 26. Thus, a track recorded at a width narrower than the width Tw exists on the medium.