US2345352A - Apparatus and method of producing products from undercooled molten metal - Google Patents

Description

March 28, J. M. MERLE APPARATUS AND METHOD OF PRODUCING PRODUCTS FROM UNDERCOOLED MOLTEN METAL Ongmal Flled July 1. 1938 wow -9 ret sted M01228, 19441 UNITED STATES PATENT OFFICE APPARATUS AND METHOD OF PRODUCING igfi IAECTS FROM UNDERCOOLED MOLTEN Joseph M. Merle, Pittsburgh, Pa.

Original application July 1, 1938, Serial No.

216,968. Divided and this application November'14, 1941, Serial No. 419,118

7 Claims.

This invention relates to apparatus and methods of producing products from undercooled molten metal.

This application is a division of application Serial Ito/216,968, filed July 1, 1938, now Patent No. 2,285,740, which is a continuation in part of Patent No. 2,129,702 which issued September 18, 1938.

While the procedure and apparatus disclosed in my Patent No. 2,129,702 and the products produced are eminently satisfactory, I have, nevertheless, discovered through further studies and investigations that, by making certain modifications as hereinafter described and claimed, appertaining to the apparatus there described by mercially important solid products which are characterized by excellent physical properties me, I make .it possible to produce new and comand by a special new primary crystal structure.

It is, accordingly, one of the objects of my present invention to provid apparatus which is especially suitable for the production of new products from undercooled molten materials.

Another object of the invention resides. inapparatus which is simplified as compared with previous apparatus and which is subject to close and accurate control, thus'givi'ng new and additional advantages over such prior apparatus.

A further object of the invention resides in the provision of apparatus which mechanically and vfunctionally represents advances over what has been heretofore developed in this art and which is sensitive to control'iactors and to the particular nature of the molten material handled thereby, in which connection the apparatus is susceptible of adjustment so as to vary the so-called undercooling period.

A still further object of this invention is the discovery and definition" of means and conditions for the continuous treating of'molten metproducts from a divided and recombined stream alsandalloys preliminary to their introduction" into'a forming means to produce-and control a definite state of undercooling such as will indues and create in the finished solid metal prod-.

new prinot a line, uniform and homogeneous mary crystalline structure.

Another object of this invention is the description of commercial machinery and equipment developed to continuously undercool under controlled conditions molten metals and alloys or non-metallic materials previous to their introduction into forming means, and to subsequently introduce or force the undercooled metal or allo without any change in its condition or composition into the forming means in the form of a thin consolidated stream projected under controlled velocity to produce metal products with the above homogeneous fine crystalline structure,

Another object of the invention is the produc:

tion of metal products of-many kind from metals and allows in a controlled undercooled state orwithin their plastic range and not from metals and alloys in their molten state.

Another object of this invention resides in pro-- cedural features and steps for continuously treating metals and alloys in their molten stateto place them in any desired state of undercooling and in that state of undercooling to introduce them into a forming means without disturbin'g, affecting, or modifying their original homogeneous chemical composition .or inherent characteristics in any manner and without, any contact with or contamination by outside gases or air, none being required or used for cooling, propelling, or impacting purposes in tion.

Other and further objects and advantages reside in the various, combinations, subcombinations, and details of construction hereinafter de-' scribed and claimed, and in such other and furthe:- matters as will either be understood by those skilled in this art or will be apparent from the following description. I

In the accompanying drawing, the figure is a vertical sectional .view, partly in elevation, of an apparatus adapted to mold or die cast individual of molten metal or other molten material.

The method and metallurgical process present in the production of the products according to my present invention are clearly set forth-in my Patent No. 2,285,740, of which this lsa division, so will only herein be' described in so far as is necessary to make my present invention readily understandable.

metals and alloys have shown that this condition may exist in metals undercooled 0.1 to 0.3- C.; for other metals such as gold, copper, bismuth,

' antimony, lead, tin, and a number of alloys undercooling may reach 30 to 45 C. so that all metals and alloys can be placed in an undercooled condition in which they retain most of the this inven mobility of a liquid, although part of the solid phase may be precipitated, and in that condition the metals and alloys flow and shape themselves in molds or dies.

To make clear the distinction between the molten and the undercooled states, above referred to, the molten state is that in which the molten metal or alloy is liquid and capable of flowing freely by gravity; its total heat content is the amount of heat required to bring it to its fusion point plus the amount of heat required for its latent heat of fusion plus the extra amount of heat put in as superheat for commercial handling which may range from a few degrees F. to 200 to 300 degrees F. as in the case of steel or alloy steel or other high melting point metals or alloys. The undercooled state as applied to metals and alloys and which I propose to establish and control is a condition which results from treating any molten metal or alloy as produced by present commercial furnaces to remove from it all its superheat of fusion and all or most of its latent heat of fusion to bring its temperature either close to its crystallization point or slightly therebelow for metals and alloys having a long plastic range before the treated metal or alloy is introduced or forced or propelled into a mold or die or between rolls at a definite velocity.

This undercooled metal or alloy introduced into molds or dies or between rolls in that condition has still most of the mobility of a liquid and will, under the velocity at which it is propelled, readily shape itself to the contour of molds or dies. Itis further characterized by the fact that each of its minutest component particles has already a crystal nucleus extending to part or to the whole of each particle depending upon how much of the solid phase has been precipitated as controlled by the degree of undercooling. These undercooled particles propelled in a stream into a mold or die will. simultaneously conform to the contour of the mold or die to fill it and practically spontaneously crystallize from an infinite number of crystal nuclei throughout th whole mass of'the formed product, which creates in the formed product a crystalline structure made of very small stringer-like at random crystals homogeneously and uniformly distributed throughout the whole solid metal product, this bein strikingly different from the primary structure obtained from molten metal or alloy as described hereinbefore.

metal or other molten substance flowing out of Y a furnace spout orpouring nozzle at the normal pouring temperatures industrially used and at a certainrate of velocity of flow-as determined by the head of metal in furnace which contains it or as governedby mechanical pumps or valves which propel it out of the container-is intercepted by; aclean, colder solid metal or non-metallic surface free of moisture moving at auniform rate of speed greater than the velocity of stream,

at the intersection-wher :the liquid and freely the receptacle ladle, or r face. This layer is hydrostatically self-leveling while being carried across the molten stream and carries with it as much of the molten metal or substance as it can attract under its intrinsic forces of atomic attraction and molecular cohesion. There is thus formed from the molten metal stream a continuous film or layer of uniform section and thickness which is adheringly carried by the solid moving surface to which the film or layer gives up heat from the instant contact is established.

The cross-section of this molten metal film is directly determined and controlled by the following relation:

Its cross-sectional area multiplied by the velocity of the moving metal surface carrying it is equal to the cross-sectional area of the molten metal of the molten metal stream multiplied by its velocity of flow.

For example, if a stream of molten metal flowing from a rectangular nozzle 2 inches wide by V2 inch thick at a velocity of 2 feet per second is laid upon a metallic surface moving at 50 feet per second, or 25 times as fast, the molten metal film will have a section as follows: 2 multiplied by /2 multiplied by 2 and divided by 50 equals .04 square inch, and the thickness of the film will be .04 divided by 2 inches or .020 inch.

From the foregoing, it is clear that any definite amount of heat content can be removed from any molten metal or other film either to cool it slight- 1y, to undercool it to any desired dcgreeor to completely solidify it in such manner that the film can be continuously used when it reaches the desired temperature or undercooled condition. The latter, as stated, results from a definite time and length of contact with the moving surface. The fully formed film is continuousl separated from the moving cooling surfacelat a precisely predetermined point after it has had a definite length of contact with suchsurface. As the film is removed it is continuously directed to and introduced into a mold or die prepared to rcceive it.

By undercooling the molten alloy to the point where it will spontaneously crystalliz throughout the mass-of the solid product formed, in accordance with my invention, the original homogeneous composition of the alloy in the molten state is fully retained in every one of the minute crystals formed and such is retained after mechanical working and heat treating. This entirely new and different structural crystalline condition considerably increases the known intrinsic properties of these alloys their usefulness.

Referring now to the drawing, the figure illustrates a form of cooling and impacting machine faces. used. are .the faces of rapidly rotating cooled cylinders or rolls. A

in which the metalpropelling and cooling surframe casting 5| supports two stationary shafts .52 .and-531upon which yoke pieces 54 and 55 are,

a mounted for swinging movement in a yertical flow of the. molten metals: 9. continuous .areaofcontact is created l.

mobile metal or substance instantaneously shapes itself to the solid moving surface. This I term a wetting action. Under these conditions the molten or liquid metal is instantaneously and continuously carried away from the main body of the liquid stream, being pulled away from under it in a layer adhered to the moving surplane.

is connected by .hollow arms swing in spaced slots 63 mounting fora water cooled ring 51, Said ring 60. The ends of said hub are in the form of a hollow shaft 6! and are supported in bearings and widens the field of two closely spaced main A yoke end 56of yoke piece. 54 forms a 58 and 59to'a hub .ameter of the ring face 51a of the ring 51. When ring 51 and gear are in an operating position,

6G in each arm 59. The coolant is thus returned to shaft 6| which has water intake connections at one end and water oiftake connections at the other end to provide for the continuous circulation of water or other coolant.

Similarly, in the yoke end it of yoke piece 55 there is supported a water-cooled ring it connected by hollow arms 12 and 13 to hub 16 whose ends in the form of hollow shaft 15 are supported in bearings 16 of yoke '55. This shaft 15 extends outside of .yoke 55, the extensions being free to swing in slots 11 formed in opposite sides of the main frame casting i. On the extended end of shaft there is keyed or secured a gear 13 of the same or about the same pitch diameter as ringface 19 of ringv 18. When this ring 15 and gear 18 are in operating .position, asshown, the gear 18 will mesh with gear 65, the rotation of which will rotate the face 19 of ring 1i in the opposite direction from and at the same peripheral speed as ring face 51a of ring 51. Ring H is cooled by water circulation in the same manner as already described .in connection with the ring 51.

Yoke pieces 54 and 55 have an extended. arm 55a. and 55a, respectively, as shown. A r'od 3t supporting a plate Sta at the bottom is attached to each of these arms. Grooved weights at rest on plates 86a and can be so adjusted as to counterbalance the yokes 56 and 55, the rings 51 and H and their gears under a positively adjusted load] With the arrangement just described the rings 51 and 1| are fioatingly mounted to separate and permit foreign material, such as slag, to pass therebetween.

The width of face 19 of ring 1| and face 51a of ring 51 is' suitably made or selected in each case for the width of metal film desired to be produced. The thickness of these cylindrical faces and the material of which they are made, for example,

steel, cast iron, copper, or other high heat conductivity metals, are so selected and determined as to remove a definite amount of heat from films of various molten metals or substances of various thickness which are to be formed and carried thereon for definite and adjustable lengths of contact as governed by the factors above explained. As previously indicated, the surface condition of these faces 19 and 51a can be made such as will appropriately influence the rate of heat conduction from the molten metal film depending upon the results desired in any given instance. The diameter of rings 51 and 1t is made large enough so that the heat conducted to any portion of faces 51a and 19 will be dissipated from it by the cooling system before that portion again receives molten metal.

A receptacle 82 is positioned over the upper bight between rings 51 and H by means of brackets 83 of frame 5|. This receptacle is adapted to receive molten metal or other 'molten substance from a melting furnace or ladle, not

shown, and to maintaina molten supply for operating purposes. It may have a stopper 84 actuated by a goose neck and operating lever of known construction to open and close nozzle 85. Thus a continuous stream of molten material may be discharged through the nozzle 85 or successively regulable amounts of molten material may be intermittently discharged.

Under the receptacle 82 I provide a distributing chamber casting 85 in the form of a closed rectangular channel. This chamber casting is wider than the faces of the rings and has the two faces opposite these rings machined complementarily to the radius of the rings. There-is a' slot in the middle of the casting made to correspond to the maximum width of film to be formed by the machine but narrower than the width of faces 251aand it so that the edges of the slot will leave enough surface bearing against the ring faces to insure a perfect, air seal between the casting 8t and said rin faces when these rings are rotated. This arrangement provides an opening of definite size between the ring faces at their points of contact. Recessed or grooved sides 31 are provided in the casting dd which serve to confine or retain in place a side packing, thus further sealing the edges of. rings 5i and 1B; In-- side of casting 86 I provide-a cored casting t8 which forms a rectangular chamber having two slots 89 and d0 of selected width and thickness.

The metal stream 93 from nozzle 85 flows through the rectangular chamber, which is preferably lined with refractory material, and is divided into two equal streams which discharge through the said slots dd and 98. Each of these two streams contacts one of the ring faces did or 19, shapes itself thereto and is carried by it in the form of a separate film 92 or 93, the dimensions of which correspond to the supply slots 89 and 9d. Both films travel at the same speed for a definite length of contact with the cylindrical cooling faces, this length having been previously calculated and then secured by appropriately adjusting the positions of the feeding slots 89 and 99 so that the required amount" of heat will be removed from the films at the instant the predetermined length has been traveled. When reaching that point the two separate films are caused to aggregate or consolidate into a single recombined film or strip dd. This may be done by setting the space between ring face 51a and 19 equal to the total thickness of the two films. The further travel of the consolidated film is .along a vertical straight line as will be understood from the drawing.

This film 84 travels in the direction stated through bottom channel chamber 94a absolutely free from air contact and friction against the walls of this channel; consequently, in an unbroken, undivided and unoxidized form it reaches the feeding opening of a mold or a die 95 to impact and shape itself under its velocity of motion to the contour of the cavities or irnpres-' sions 96 of this mold or die.

A ductor pipe 91 leads to the space 98 to exhaust air from it so as to carry out the whole operation'in a'vacuum orto circulate or introduce gases of various compositions thereinto when it is desired to operate in a special atmosphere to induce a desired chemical reaction with the film or films of molten metal.

While mold or die d5 may be of any suitable form and construction, 'I have illustrated one in two parts, each of which is connected by a rod '99 to an air or hydraulic piston indicated at I00.

The die is provided with core-plates l! and ejector pin plates I02. It is to be understood,

however, that other types of molds or dies may be supplied by this machine such as ingot molds,

sand molds or continuous molds. 'Ihe machine of the drawing can. be designed for such size or capacity as will form, cool and direct a thick consolidated film at relatively low speed into a mold or it can be made of such size that it will withstand high peripheral wheel and face speeds to form two very exceedingly thin metallic films only a few thousandths of an inch in thickness and propel the film consolidated therefrom into dies or mold cavities without any frictional loss of speed at velocities unobtainable with present die casting machines. The die-cast or other products" will, moreover, be characterized throughout their entire mass by the new and desirable primary chill structure hereinabove described.

The foregoing is intended as illustrative rather than restrictive, and I may make. suitable changes therefrom without departing from the spirit and scope of the invention.

I claim as my invention:

1. In an apparatus for undercooling moltenmetal and producing solid metal products of a primary crystal structure therefrom, a frame, a pair of rolls mounted on said frame for rotational movement with respect thereto about a pair of parallel spaced horizontal axes, means for'driving said rolls at the same speeds in opposite directions, means for discharging a consolidated stream of molten metal onto at least one of said rolls in such a manner that at least one of said rolls will undercool and shape said stream of molten metal into a thin film and discharge said film by impact into a formingmeminto a thin film and discharge said film of metal her disposed beneath said rolls, and a separate floating mounting for each of said rolls, .urging said rolls towards each other to provide a predetermined relatively thin spacing between said rolls, but permitting movement of said rolls away from each other.

2. In an apparatus for undercooling molten metal and producing solid metal products of a primary crystal structure therefrom, a frame, a pair of rolls mounted on said frame for rotational movement with respect thereto about a pair of parallel spaced horizontal axes, means for driving said'rolls at the same speeds in opposite directions to form a downwardly moving path between adjacent'surfaces of said rolls, means for discharging a quiescent consolidated stream of molten metal onto said rolls in such a manner that said rolls will undercool and draw out said stream of metal into a thin film and accelerate and discharge said film at a high velocity, a separate floating mounting for each of said rolls, permitting movement of said rolls away from each other to permit the passage of foreign material therebetween, and means for yieldably urging said rolls towards each other to provide a predetermined thin path therebetween during normal operation thereof.

3. In an apparatus for undercooling molten metal and producing solid metal products therefrom, a frame, a pair of rolls, a receptacle for molten metal mounted on said frame over the bight between said rolls, a plurality of outlets in said receptacle, each of said outlets leading to the periphery of one of said rolls above the bight between said rolls, so said rolls will draw out and accelerate and undercool separate streams of metal and re'consolidate said streams of metal at a high velocity in-an undercooled condition into a shaping member placed below the bight between said rolls, means for mounting said rolls on said frame for rotational movement with respect thereto about a pair of parallel spaced horizontal axes and for movement towards or from each other, and other means for yieldably urging said rolls towards each other to provide a predetermined thin spacing therebetween during normal operation thereof, but permitting movement of said rolls away from each other, to permit the passage of foreign material therebetween.

4. In an apparatus for undercooling and producing solid metal products from undercooled molten metal, a main frame, a pair of rolls rotatable about a pair of parallel spaced horizontal axes, means for mounting said rolls on said frame for bodily movement towards or from each other, means for driving said rolls at the same speeds and in opposite directions, a receptacle for molten metal mounted on said frame over the upper bight between said rolls, an orifice in the bottom of said receptacle, a chamber below said receptacle, said chamber having spaced outlets adapted to discharge the molten metal onto said rolls and merging into a single outlet in registry with the receptacle orifice, said chamber having opposite faces substantially conforming to the arcs of said rolls and said rolls being adapted to contact said opposite faces in an air tight manner. and means for urging said rolls in a direction towards each other and for normally maintaining said rolls in contact with said opposite faces of said chamber.

5.-In an apparatus for undercooling and producing solid metal products from undercooled molten metal, a main frame, a pairof swingable yokes mounted on said main frame for movement about a pair of parallel spaced horizontal axes,

a roll rotatably mounted on each yoke, adjacent the end thereof opposite from said pivotal mounting, means for driving said rolls at the same speeds and in opposite directions, a .receptacle for molten metal mounted on said frame over the upper bight between said rolls, an orifice in the bottom of said receptacle, a chamber below said receptacle, said chamber having spaced outlets merglng into a single outlet in registry with the receptacle orifice, said rolls being adapted to contact said chamber in an air tight manner, and means for normally maintaining said rolls in contact with said chamber.

6. In an apparatus for undercooling molten metal and producing solid metal products of a primary crystal structure therefrom, a frame, a pair of rolls mounted on said frame for rotational movement with respect thereto about a pair of parallel spaced horizontal axes, means for driving said rolls at the same speeds in opposite directions, a receptacle for molten metal disposed above the upper bight between said rolls,

means for gravitationally discharging a stream of molten metal from said receptacle and dividing it into two parts and causing eachpart to engage one of said rolls and to be accelerated and be drawn by said rolls into an undercooled film moving at a, high velocity and be recombined at the bight between said rolls into a composite film, and be discharged by said rolls at a high velocity to be shaped by impacting in a die or mold.

'7. A method of making a metal product hav ing a. primary crystal structure of a regulated number of uniformly distributed crystal nuclei, which consists in gravitationally discharging a stream of molten metal and subdividing this stream into two streams, intercepting each such stream by a rapidly moving cool clean metallic surface, forming each such stream into a thin film by said metallic surfaces and accelerating and undercooling each such film and reconsolidating these streams into a single film travelling at a high velocity, and discharging said film into a forming member and forming said film to the form oi said member by its impact of discharge from said surfaces;

JOSEPH M. MERLE.

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