US1978220A - Method of and apparatus for treating metallic materials - Google Patents

Description

Oct. 23, 1934. o. M. OTTE METHOD OF AND APPARATUS FOR TREATING METALLIC MATERIALS Filed Aug. 31, 1952 INVENTOR l /l Il Il. 1/1 r 4 l- .A L 274, y /f/v/ APau-,mai oer. v22., v19:94

UNITED STATES PATENT OFFICE METHOD OF AND APPARATUS FOR TREAT-v ING METALLIC MATERIALS k Pennsylvania 1 Application August 31, 1932, serial No. 631,199

9 Claims. (Cl. 175-21) This invention relates to a method of andapparatus for working metallic materials so that materials so worked shall be superior to similar prior art materials and uniform, insofar as possible, in quality with respect to their physical and/or magnetic properties particularly the latter.

This invention is directed primarily to the rolling of material suitable for use in magnetic circuits for electrical apparatus, of all kinds, wherein permeability and low watt loss are of considerable importance, and wherein the physical properties from the standpoint of hardness, strength, toughness and workability are also of considerable importance, especially the latter.

In the light of present knowledge and experience, it appears that the invention may be of more importance in the production and manufacture of electrical sheets particularly those of silicon steel composition. While the invention may have more utility in the production and manufacture of this kind of material it is appreciated and it is to be understood, that other metallic materials whether paramagnetic or diamagnetic may be produced in accordance with this invention;

and that materials so produced will be superior to similar prior art products, in respect to their physical and/or magnetic properties.

Electrical sheets, particularly those of silicon steel composition as produced by prior art methods, have not been uniform either in respect to their physical or magnetic properties such as permeability and watt' loss. Some portions of the same sheet of a pack worked under identical l y conditions of temperature and rolling technique,

will have comparatively good magnetic qualities,

that is, high permeability and low watt loss, and

other portions, taken from the same sheet willA have poor permeability and high watt loss.

In order to obtain sheets each having the desired standard of quality in respect to magnetic properties it has been the practice heretofore, to test each lift (a quantity of sheet material) for permeability and watt loss and select only those lifts which meet the standard of quality, the

lifts of inferior quality being classified as of lower or inferior quality. So far as I am aware, no solution has been offered by those skilled,in the art that explains or accounts for these variations. I am of the belief, based on a study of the molecular theory of matter, and of the molecular rearrangement which occurs in the structure of metal while cooling down from a temperature above the rang at which molecular rearrangement occurs, that nonuniform products result because molecular rearrangement is more vcomplete in some sheets of a pack than in others of the same pack. Further, I am of the belief that nonuniform magnetic properties are found in different portions of the same sheet because molecular rearrangement does not occur uniformly throughout the body of the sheet.

If, therefore, some additional force be applied to the material while being rolled or worked, to cause complete molecular rearrangement, mate- 05 rials having uniform magnetic properties and/or improved physical properties should result.

In other words, I am of the belief that the resistance offered by metallic materials (whether magnetic or non-magnetic) to molecular rearrangement is not uniform throughout the body of the material, with the result that in the production of electrical sheets, for example, molecular rearrangement is more complete in some sheets of a pack than in others, and that in the case of individual sheets, such rearrangement takes place more completely in some portions thereof than in others.

In accordance with this invention, I subject the material to a force, while it is being rolled and while cooling down to and through the temperature range in which molecular rearrangement occurs, which, in conjunction, with the mechanical forces of rolling or working while at such' elevated temperature, will accentuate molecular 5 rearrangement and cause such rearrangement to occur uniformly throughout all parts of the material, and, as far as possible, approach completion. By so treating and working the material, the finished product will have superior magnetic and/or physical properties in comparison to the best products of a similar nature now on the market.

The vadditional forces which I interpose on the forces of temperature or mechanical working is 95 that of magnetismz-that is, while hot rolling or l working, I subject the material to the action and influence of a magnetic field forthe purpose of accentuating those fundamental changes which occur, and which apear to have so much bearing on the quality of the physical and/or magnetic properties vof the finished product. As stated above, it is my belief that these changes are the result of, or are strongly influenced by molecular 1 rearrangement which occurs while the metal passes from the non-magnetic to the magnetic state, or which occurs most actively while the ma.- terial is passing from a temperature above that .at which it is magneticdown and through the temperature defined by the dec'alescent and recalescent points of the material.

By subjecting the material to a magnetic eld or magnetizing forces while being rolled or worked at elevated temperatures, the portions of the material that otherwise offer great resistance to molecular rearrangement will be ,given that added force which will cause it to undergo the same fundamental changes ithat otherportions of the material undergo. Having thus obtained uniform molecular rearrangement throughout the body -of the material, products having uniform properties both mechanical or physical and magnetic-will result.

An object of this invention is the provision of a'methodof treating and/ or working' metallic materials whereby the finished product will have physical and/or magnetic properties that are superior to the properties of similar products produced by prior art methods.

Another object of the invention is the provision of a method of producing magnetic material that shall have higher permeability and lower jwatt loss than materials now on the market of the same composition that is, of the same analysis.

Another object of the invention is the provision of a method of treating and working magnetic materials whereby electrical sheets may be .produced having higher permeability and lower watt lpss than the best products now on the market of substantially the`v same metallurgical composition. l

Another object of the invention is the provision .of a method of producing magnetic materials such as electrical sheets that shall result in products having uniform magnetic properties and superior physical properties so as to reduce the ratio of inferior to acceptable quality products.

A further object of the invention is the provision of electrical sheets such as silicon steel, that shall be so pliable that it may be folded, doubled p and redoubled without fracturing or rupturing the same.

Other objects of the invention will in part be apparent, and will, in part, be obvious from the following description taken in conjunction with the accompanying drawing wherein apparatus/is illustrated for. thepurpose of showing how the method may be carried into effect.

'In the drawing:

Figure 1 is a diagrammatic view of a rolling mill and apparatus for passing electric current vthrough the material being rolled in the mill;

Fig. 2 is a modified form of a contact device :adapted to be used with the apparatus of Fig. 1;

Fig. 3 is a diagrammatic illustration offa circuit for use with direct current which may be applied to the rolling mill of Fig. 1.

Figs. fand 5 are side and end views, respectively, drawn to reduced scale, of a modified form of roller electrodes that may be used in the mill of Fig. l' and Figs. 6 and 7 are top plan and side views, respectively, drawn to reduced scale, of further modified forms of electrodes that maybe employed. Generally stated, the invention contemplates the rolling of a starting piece, such as billet, or bar, through the required number of reducing and finishing passes to produce the final product. The material, of course, may be worked hot or cold, and annealed between some or all of the passes, depending vupon the particular rolling technique or heat treatment required by the particular material under consideration.

While the material is-being rolled, it is subjected to the action of electric current which is passed directly through the material preferably in the direction of elongation. The current may be passed through the material. either at the entering end'or the delivery side of the mill or both.

In the light of present knowledge and experience, it is proposed to pass the current through the material disposed on both sides of the mill, that is on the entering and delivery sides and to concentrate the current at-the squeeze point of the mill rolls.

The current may be periodic or aperiodic dei pending on which is best suited to the particular material under consideration.

The effect of the current is to assist' and/or accentuate the occurrence of those fundamental changes, which take place in metal when worked hot or cold, that are so benecial to the physical and/or )magnetic properties thereof. The passing of `current at high density or amperage through the material creates a magnetic field which envelops 'and permeates the same. Such field may also assist and accentuate the occurrence of these changes.

'I'hese changes mentioned above occur also as the result of rolling only, whether hot or cold, but for some reason or other, the changes do not take place uniformly or to the same extent throughout-the body of the material. It is quite generally recognized that these changes are in the nature of molecular rearrangement.

In the light of present knowledge and my'experience in this art, it -is my belief that certain portions of the body of the material, being rolled or worked, offer greater resistance to the occurroo rence of these fundamental changes, or molecular rearrangement, than others, `with the I.result that the finished product is not uniform throughout in respect to its physical and/or magnetic 116 properties.

If, therefore, the material be subjected to an extraneous force, in addition to the .forcesvof heat and/or mechanical working or rolling, such that will cause these fundamental changes or 120 molecular rearrangement to occur with more uniformity throughout, regardless of variations in the resistance which different portions of the material offers to such changes, a product uniform in physical and/or magnetic properties, and of superior quality in such properties should result. l

The additional extraneous force which may be employed, as stated above, is that of electric current with its attendant magnetic field, both of 180 which tend to assist and accentuate the occurrence of these fundamental changes or molecular rearrangement.

'I'he action of the current appears to cause uniform parallel alinement of the crystals and in'- 135 creased rearrangement of the molecules; with the proper polarization or orientation, which might not otherwise occur to such marked degree, thereby improving the quality of the product.

An arrangement for carrying out the method is shown in Figure 1. In this figure, a rolling mill, including rolls 1 and 2, is diagrammatically illustrated, the screwdowns and other appurtenances which enter into the makeup of a complete mill being omitted for the sake of sim- 34.5 plzicity. The material being rolled is' indicated a 3.

While the material is being rolled, current is 1 passed longitudinally, that is, in the direction of rolling and"elongation, through portions of the 15 material disposed on the entering and delivery sides of the mill. Current may be derived from a transformer 4 having a relatively high voltage primary winding 5 and a low voltage winding 6 of high current capacity.

The electrical mid-point or neutral tap of winding 6 may be connected to a roller electrode '7 having rolling contact with mill roll 2. The opposite terminal of Winding 6 may be connected to movable roller electrodes 8. Electrodes 8 engage the material 3 on opposite sides of rolls 1 and 2 and are backed by idle backing rolls 9 adapted to engage the opposite face of the material and to prevent the material from moving away from the roller electrodes. i

When the material is engaged by the roller electrodes, as shown, current flows in parallel paths as indicated by arrows 10, from electrodes 8 towards the mill roll, concentrates at the squeeze point thereof, through roll 2 and roller 'l back to the neutral or electrical mid-point of winding 6. It is thus apparent that current flows through the material in the direction of elongation, which is also the direction of crystal deformation.

In order that thel roller electrodes 8 may yieldingly engage the material and follow variaelectrodes may have vertical motion to compensate for irregularities in the material and at the same time make positive contact with the same. v

Each roller electrode may be as wide as the material being rolled, or a plurality of narrow rollers 15 may be employed. Rollers 15 may be disposed in line crosswise of the material as y shown in Figs. 4 and 5 or in overlapping but staggeredfrelation crosswise of the material as shown in Figs. 6 and 7. 'I'he rollers shown in Figs. 4 and 5 and 6 and 7 may be journaled in vertically movable supports 17, and these sup'- l ports may be spring loaded as inthe case of supports 11 shown in Fig. 1.

With the rollers arranged as shown in Figs.

4 and 5, or 6 and PLeach roller will adjust itselfto the contour of the material in contact therewith. Thus uniform now of current through the material results;

Instead of using roller electrodes, such as -8 or 15, contact shoes 18 (see Fig) 2) may be provided and mounted on vertically movable supports 19. lSupports 19 may also be yieldingly mounted on springs as'are supports 11 in Fig. 1. Shoes 18 may be made of material 'thatwill resist the effect of high temperature and arcing and the area of the contact surface thereof may be ,made such that currents of high amperage, say 2000 amperes more or less, may be transferred to the material without overheating or burningV the same. i

In Fig. 3 a circuit is shown whereby direct `current may be delivered to material 3 through the roller electrodes. For convenience, the elec--v trodes of Fig. 3 are designated by the same reference characters as applied to the electrodes of Letters Patent is:

Fig. 1. As shown, roller electrodes 8 are con nected to one terminal, say the positive, of the direct current supply, and roller electrode 7 is connected to the negative terminal. Thus, as the material is being rolled, current flows as indicated by the'arrows.

In accordance with the methods described above, the material being worked or rolled is subjected to the action of electric current of sufficient density to act as a force, which in conjunction with the forces of working or rolling and/ or temperature results in improvement of the physical and/or magnetic properties thereof. The magnetic field developed by the current lalso acts on the material so as to assist in the occurrence of these beneficial changes that it is desired to take place therein.

As pointed out previously herein, some material may be worked cold and others hot. For example, in the working of electrical sheets of silicon steel composition, it is preferred to heat such materials, prior -to working or rolling, to a temperature above the range in which molecular rearrangement,

occurs, or to a temperature at which it is nonmagnetic and then roll or work the material as it cools down into said range or to the temperature at which it becomes magnetic. While the material is being so worked and cooling down, electric current is passed therethrough. The combined action of working, temperature and current with its attendant magnetic field results in an improved product in respect to the properties mentioned herein.

Since the method herein described and tappa# ratus disclosed for carrying the method into effect both admit of changes and modifications within theA spirit and scope of the invention, it is desired that only such limitations shall be placed on the invention as are imposed by the prior art and the appended claims.

What I claim as new and desire to secure by 1. The method of improving useful properties of metallic material, that comprises heating the materia/l to a temperature above that at which molecular rearrangement occurs, subjecting the heated material to working stresses of suicient intensity to produce deformation and, while so working, passing electric current through the heated material, of sufficient intensity to permeate the material with magnetic lines of force while the material is passing from said temperature into the range at which molecular rearrangement occurs, and maintaining said current flow while the temperature of the material passes through saidrange.

2. The methodv of improving the physical and/or magnetic properties of metallic materials that comprises hot rolling the material through a series of reducing and finishing passes, and while hot rolling passing electric current through thematerial during at least one of said passes.

3. The method of improving the physical and/or magnetic properties of metallic materials that comprises hot rolling the material through a series of reducing and finishing passes, and while hot rolling passing electric current through the material disposed on the entering side of the rolls during one or more of said passes.

4. The method of improving the physical and/or magnetic properties of metallic materials,

that comprises hot rolling the material through a series of reducing and finishing passes, and passing electric current through the material disposed on the entering and discharge sides of the rolls during one or more of said passes.

5. The method of improving the physical.

and/or magnetic properties of metallic materials that comprises hot rolling the material through a series of reducing and iinishing passes, and passing current through the-material'disposed on each side of the rolls and concentrating the current at 'adl the line of rolling press/ure, during one or more ofsaid passes.

`6. The method of improving .the physical 'and/or magnetic propertiesof metallic materials that comprises heating the material to or about the temperature at which-molecular rearrangement occurs, working the material under deformation producing stresses,- and'passing electric current of high amperage through the material in a direction parallel to the directionof deformation.

7. The method of improving physical and/or material disposed between the squeeze point and predetermined points on each side thereof, in a direction parallel to the direction of elongation. 9; The method of improving the physical and/or magnetic propertiesof metallic materials that comprises hot rolling the material through a series of reducing and iinishing passes, and passlng electric current through the material disposed on the delivery side of the rolls during one or more of said passes.

OTHO M. O'lTlfl.

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