US1320309A - Arthur francis berry - Google Patents

Description

A. F. BERRY.

TREATMENT OF MAGNETIC MATERIAL.

APPLICATION FILED JUNE 25 1918.

1,320,309. Patented Oct. 28,1919.

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ARTHUR FRANCIS BERRY, OF LONDON, ENGLAND.

TREATMENT OF MAGNETIC MATERIAL.

Specification of Letters Patent.-

ratentea oct. 28, rare.

Application filed June 25, 1918. Serial No. 241,754.

To all whom it may concern:

Be it known that I, ARTHUR FRANCIS BERRY, a subject of the King of Great Britain and Ireland, residing at London, England, have invented Improvements in or Belating to Treatment of Magnetic Material, of which the following is a specification.

This invention has for its object to improve the magnetic properties of magnetic material, such for example as iron produced by the open hearth, pneumatic or other metallurgical process, or electrolytically, and also iron alloys, compositions or the like, as for example iron-silicon alloys, so as to reduce' the hysteresis loss that takes place in such material during its use in alternating current apparatus, and also to increase the magnetic permeability or electrical resistance, or both the permeability and the resistance, of such material and thus to render such material better adapted for use in apparatus of the kind referred to, particularly static transformers, than the magnetic materials heretofore commonly employed.

With this object in View it has been proposed to subject magnetic material while in a heated condition to a magnetizing force by surrounding it with a coil of Wire that is insulated from the magnetic material and, through which a continuous or alternating electric current iscaused to pass, the magnetic material forming a core to the coil and being magnetized by the current passing through the coil.

The present invention has reference to improvements in the treatment of magnetic material whereby such material is better enabled to assume the physical condition necessary for enhancing in a high degree the desirable characteristics which magnetic material designed for use in alternating current apparatus should possess.

For this purpose according to the invention, magnetic material is subjected while in a heated condition, to the magnetizing and demagnetizing action of alternating electric current while confined in an air tight chamber wherein a vacuum'is maintained, as by a vacuum pump, so that the material is relieved practically from all external pressure and its particles or molecules thereby better enabled to move alternately in opposite directions in response to the alternating magnetizing and demagnetizing action produced by the alternating current to which the material is subjected. This treatment of the magnetic material is or may be maintained during the heating up of the material and also during the cooling thereof.

In this way the magnetic material is rendered less dense than ordinary magnetic material and much less dense than such material that has been put under great pressure while in a molten condition, as has sometimes been done.

The invention can be carried into practice in various Ways as will now be described with the aid of the accompanying illustrative drawings wherein Figures 1, 2, 3 and l are views showing partly in longitudinal section and partly in elevation and .diagrammatically, different arrangements of apparatus for the purpose.

1 is a vacuum chamber closed at its end by air tight covers 2 and adapted to contain the magnetic material 2 to be treated. 3 isa heating chamber in which the vacuum chamber. is supported and through which gases at a sufficiently high temperature to heat the interior of the vacuum chamber and its contents to the desired temperature, say up to a temperature of the order of about 750 to 800 0., can be caused to flow, 4 and 5 being inlet and outlet passages respectively for the hot gases. 6 is a vacuum pump connected to the Vacuum chamber 1 and whereby a vacuum or partial vacuum can be set up therein. 7 is a coil of wire connected to an alternate current generator 8 whereby an alternating electric current can be caused to flow through the coil 7 for the purpose of subjecting the magnetic material 2 to an alternating magnetizing and demagnetizing force. 9 is a switch by which the electric circuit can be closed and opened at will. The coil 7 may be insulated in any suitable manner to prevent its convolutions being short circuited and, when necessary, to protect it against the action of the hot gases.

The alternating current may, as shown in Fig. 1, be passed through a coil 7 sur rounding the material 2 within the vacuum chamber 1, the coil being within the chamber with the magnetic material, but insulated therefrom. Or, as shown in Fig. 2, the

coil may be outside the vacuum chamber 1.

In each case the vacuum chamber may be of tubular shape the better to enable it to Withstand the external air pressure.

Or the heated magnetic material 2 may, as shown in Fig. 3, be subjected to the mag netizing and demagnetizing force by including it in a magnetic circuit formed partly byan external magnetic core 10 between the poles of which the magneticmaterial 2 is placed and which is subjected to such a force at a part thereof situated away from the heated portion of the magnetic material 2 as for instance by a coil 7 surrounding such part traversed by an alternating current. In this case the material 2 extends in an air tight manner through the end walls 2 of the vacuum chamber 1.

The alternating current passing through the coil in each case can be of constant or varying strength and of constant or variable periodicity and be caused to pass through the coil either continuously or intermittently so that the material will be subjected to an alternating magnetizing and demagnetizing force of constant or variable value and either constantly or intermittently.

The magnetic treatment may advantageously be carried out while the material is heated to a high temperature within its limits of magnetic susceptibility, up say to the order of about 7 50 0., and also during the cooling of the material.

The magnetic material may be treated as described preferably While in the form of sheets, strips, bars or the like, as may be desired, and according to the particular purpose for which it is to be used. Or it may be in the form of billets or ingots.

The magnetic treatmentdescribed may be carried out during the ordinary annealing treatment of the magnetic material,- and, it may be, after such material has been rolled to the desired thickness and shape. for use.

In some cases an electric current, either direct or alternating, may, as shown in Fig. 4, be passed through the heated magnetic material while it is being subjected to the magnetizing and demagnetizing force, the current being supplied from a suitable electric generator 11 through a conductor 12 in electric connection with the magnetic material 2.

The magnetic treatment hereinbefore described may advantageously be applied to magnetic material of various kinds including, in particular, magnetic material that has previously been remelted under vacuum, in a known way, with a view to improving its magnetic properties.

Magnetically treated sheet magnetic material produced as hereinbefore described may, previous to use in electrical apparatus and for the purpose of further improv-- ing its value for such use, be grooved, or grooved and insulated as and for the purpose described in the specification of my British Letters Patent 1126-19. Such material after being so grooved and insulated may be reheated to a high temperature, say of the order of about 750 (1, and magdemagnetizin force while confined in a heated condition within a chamber in which a vacuum 1s maintained during the magnetic treatment, substantially as and for the purpose described. I

2. In carrying out the treatment referred to in claim 1, including 'the heated magnetic material in a magnetic circuit.

3. In carrying out the treatment referred to in claim 1, including the heated magnetic material in a magnetic circuit that is subjected to an alternating magnetizing and demagnetizing force as a part thereof away from the heated portion of the magnetic material, substantially as described.

- 4:. In carrying out the treatment of magnetic material according to claim 1, applying an electric current, either direct or alternating, to the heated magnetic material while it is being subjected to the alternating magnetizing and demagnetizing force, substantially as described.

5. In the manufacture of magnetic material, subjecting magnetic material which has previously beenremelted under a vacuum, and while in a heated solid condition 1 and in a vacuum, to an alternating ma netizing and demagnetizing treatment, su stantially as described. I

6. In the treatment of magnetic material, subjecting such material while in the form of sheets to an alternating magnetizing and demagnetizing force while confined in a heated condition in a vacuum, afterward grooving the sheets as set forth and afterward subjecting the grooved sheets while in a heated condition and in a vacuum, to alternating magnetizing and demagnetizing force, substantially as described.

7. For carrying out the treatment referred to in the claim 1, a vacuum chamber to contain the magnetic material to be treated, a vacuum pump for producing a vacuum in the said chamber, a coil surrounding but insulated from the magnetic material under treatment and means for causing altern-atin current to pass through the coil, substantially as described.

Signed at London, England this 5 day .of June 1918.

ARTHUR FRANCIS BERRY.

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