US3088195A - Cladding with powdered metal to form bimetallic products - Google Patents

Description

May 7, 1963 CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16, 1958 FIG R. M. NOETHLICH, JR, ETAL 7 Sheets-Sheet 1 IN VEN TORS RICHARD M. NOETHLIGH, JR, & JOSEPH G. DUNLEAVY JOHN G. KURA AND JOHN L GISSY wag 1.

May 7, 1963 R. M. NOETHLICH, JR., ETAL 3,088,195

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16, 1958 7 Sheets-Sheet 2 INVENTORS woman a. nosmuc JOSEPH e. DUNLEAV JOHN G. KURA m? .tL 1

May 7, 1963 R. M. NOETHLICH, JR. ETAL 3,088,195

CLADDING WITH POWDERED METAL TO FORM BIMETALLIG PRODUCTS Filed June 16, 1958 T Sheets-Sheet 3 JMPAW M y 1963 R. M. NOETHLICH, JR. ETAL 3,088,195

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16, 1958 T Sheets-Sheet 4 20 /490 M wErm/oq JOHW G A z/PAMHA/L'G/JJV 5% '7 W INVENTORS JOJEPH G W/VLEAV INVENTOE; emu/4P0 M NOE/'HA/CH,

7 Sheets-Sheet 5 ETAL R. M. NOETHLICH, JR,

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS J? JOSEPH a 00mm v11 JOHN 6? 02/1 .woH/v L, was) By J W 9' 74;, L? a??? Fig 18 May 7, 1963 Filed June 958 May 7, 1963 R. M. NOETHLICZH, JR, ETAL 3,083,195

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16, 1958 7 Sheets-Sheet 6 f 3% W R) NLAW v; w {WW4 Maw w? i m 3 2 W. m. k 5 a 0 Z W W.

May 7, 1963 R. M. NOETHLICH, JR.. ETAL 3,

CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCTS Filed June 16, 1958 7 Sheets-Sheet 7 INVENTORS. Haw/1P0 M NOE/'HL my, a? JOSEPH a DUNLEA W, H n Jowazum Howie/6s? ZWAM United States Patent 3,088,195 CLADDING WITH POWDERED METAL TO FORM BIMETALLIC PRODUCIS Richard M. Noethlich, Jr., Joseph G. Dunleavy, and John G. Kura, all of Columbus, and John L. Gissy, Dublin, Ohio, assignors, by mesne assignments, to Copper-weld Steel Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed June 16, 1958, Ser. No. 773,125 17 Claims. (Cl. 29182.3)

This invention relates to the use of powdered metal in the cladding of higher strength or lower corrosion-resistant metal cores to form bimetallic members. More particularly, this invention pertains to a novel system for continuously producing bimetallic rods, wires and shapes having a ferrous core and clad to a controlled cladding thickness with a conductive and/or corrosion-resistant metal, initially in powdered form, like aluminum, copper, or their respective alloys.

Elongated bimetallic members such as aluminum-clad and copper-clad wires and rods are extensively used in industry and by utilities. Thus, Copperweld copperclad steel wires and rods are used for electrically conductive wires for power, telephone and other communication or signal purposes, for weather resistant fencing, for corrosion resistant concrete reinforcement and for other electrical and mechanical uses. More recently, aluminum-clad wires with continuous ferrous cores therein have also been made and used in the mechanical and other fields. Such prior practices have most commonly involved manufacture by the application of molten metal as a cladding material to the core metal, or the use of preformed jackets subsequently welded or bonded to the core; or, as to relatively thin coatings, by hot dipping processes or certain kinds of electrodeposition.

However, it has not heretofore been possible, so far as we are aware, to manufacture bimetallic clad core members by, e.g., using a ferrous rod or wire and aluminum or copper powdered metal respectively as the respective starting core and cladding materials and meet the desired requisites of adherence between cladding and core, of density and continuity of cladding, of bendability without physical or metallurgical damage to the composite member, and, further, of drawability when such a composite member is to be further reduced in diameter by rolls or wire-drawing dies while maintaining a minimal ratio between the thickness of cladding metal and of core.

In a preferred practice of our invention, a powdered metal, e.g., atomized powdered aluminum, is applied in a positive manner to a ferrous core, roll compacted, heated, roll reduced in cross section and roll finish rounded in a continuously moving metal line operation in the air at production speeds. Such preferred practice in the case of the aluminum cladding of steel rod provides direct metallurgical bonding between cladding and core metals uniformly around the core without formation of any continuous layer or more than traces of brittle aluminumiron compound. The cladding or coating of the bimetallic product so produced is a continuous, dense, nonporous, corrosion-resistant cover. The new product itself is quickly and economically producible and satisfactory for a wide variety of electrical and mechanical services and uses including those hereinbefore mentioned.

Other objects and advantages of this invention will 3,088,195 Patented May 7,, 1963 be apparent from the following description and the accompanying drawings, which are illustrative only, in which FIGURE 1 is a schematic view in side elevation of a continuous horizontal line for one practice of this invention to provide a bimetallic clad rod or wire suitable, if desired, for further reduction in size by drawing;

FIGURE 2 is a view in side elevation, partly in section, of equipment in the zone of FIGURE 1 at which powdered cladding metal is continuously applied to a continu ous rod or wire core;

FIGURE 3 is a view in section taken along line III-III of FIGURE 2;

FIGURE 4 is a view, somewhat enlarged, taken along line lV-lV of FIGURE 2;

FIGURE 5 sets forth one illustration of a means by which rolls such as those shown in FIGURE 1 may be power driven;

FIGURE 6 is a schematic view in side elevation of an initially vertical continuous line for a practice of this invention;

FIGURE 7 is a depiction of a portion of a photomicrograph to illustrate continuous bonding provided by this invention at an interface between a ferrous core and a cladding metal like aluminum;

FIGURE 8, comprising portions 8A and 8B, is an overall view in side elevation of a horizontal line for a preferred practice of this invention to provide, e.g., an alumi num clad ferrous rod or wire in a continuous operation;

FIGURE 9 is a view in side elevation of the cladding powder applicator and compacting roll stand taken along line IX-IX of FIGURE 14;

FIGURE 10 is a partial detail view, somewhat enlarged, illustrating one mode of providing lubricant and scraper means respectively for the back and front of a roll;

FIGURE I1 is a view taken along line XIXI of FIG- URE 10;

FIGURE 12 is a somewhat enlarged view partly in longitudinal cross section of the applicator mechanism shown in FIGURE 9;

FIGURE 13 is an end view somewhat enlarged of the fin remover shown in FIGURE 9;

FIGURE 14 is a front view of the roll stand shown in FIGURE 9 with a part of the applicator mechanism removed for the purpose of illustration;

FIGURE 15 is a view in side elevation of the hotreduction roll stand to further metallurgical bonding between cladding and core;

FIGURE 16 is a front view of the fin remover shown in FIGURE 15;

FIGURE 17 is a view in section taken along line XVIi -XVII of FIGURE 16;

FIGURE 18 is a rear view of the roll stand shown in FIGURE 15;

FIGURE 19 is a detail view somewhat enlarged showing the pass opening from the front formed by the rolls of the roll. stand of FIGURES l5 and 18;

FIGURE 20 is a view in side elevation of the finish roll stand to round the clad rod and means to cool the cladding thereof; and

FIGURE 21 is a front view of the roll stand shown in FIGURE 20.

Referring to FIGURE-S 1 to 5, schematic means for practicing one embodiment of this invention are shown in the form of a continuous horizontal line of equipment on a plant floor to produce bimetallic clad wire or rod, which, for the sake of illustration, will be discussed in connection with the production of a steel core aluminum-clad rod to subsequently be cold drawn to wire size of lesser diameter. In such equipment, a payout reel support may be provided for a reel 11 on which a continuous length of ferrous rod 12 is wound. Rod 12 is maintained under tension as it passes through the line of equipment to a wind-up reel 14 on a wind-up reel support 15 which is at the end of the line shown. It is not necessary in this invention to have the core rod 12 coated with any flux, intermediate metal layer, or bond promotion agent.

Rod 12 may be passed through a straightener 16 and then may be cleaned, including any descaling that may be needed, in the illustrated line by a core cleaner 17, one form of which may be a mechanical grit-blaster such as a Wheelabrator. In such a machine 17, any scale or oxide is removed from the surface of rod 12, and if grit is used, it is such as to clean the surface of the rod without burnishing it. If desired, gaseous or liquid bath cleaning means for rod 12 may be substituted. Cleaned core 12 passes from machine 17 to a cladding applicator machine 18 and in so doing may pass through a hood or mufile, if such is necessary to protect the cleaned rod against the ambient atmosphere as when, e.g., the core is readily oxidizable. Generally such a hood or mufile will not be needed in view of the relative juxtaposition of machines 17 and 18.

Applicator 18 is used to apply powdered aluminum as the metal cladding to the cleaned steel core 12 in the illustrated embodiment of the invention under immediate discussion. Preferably, when the cladding metal is made from aluminum, it will be initially applied in the form of atomized powder having a relatively low oxide content (less than 0.3% by weight) and a screen analysis in the to 200 mesh range, US. Standard sieve, with the major portion of such powder being of a size which is under 40 and over 140 mesh (e.g., Alcoa No. 125 aluminum powder). Further, aluminum powder in other sizings (e.g., Reynolds No. 12120 aluminum powder) and in other forms may also be used.

A hopper 19 in machine 18 may be used to contain such powdered aluminum, the powdered cladding metal 50 passing downwardly by gravity into the bottom of the hopper and from thence into a feed tube 20 extending in the direction of movement of rod 12 as shown by the arrow 21. Rod 12 passes axially through hopper 19 and feed tube 20 and is coaxial with the forming tube end 22 of feed tube 20 and with a wholly closed circular pass 23 in pressure rolls 24. A vibrator 25, such as a Syntron, may be affixed to hopper 19 to vibrate in a manner to assist in the continuous feeding of aluminum powder into feed tube 20 and from thence evenly around core 12 in discharge end 22 immediately before core 12 and the applied powdered metal for the cladding around it move into the bite of circular pass 23 formed by cooperating grooves 27 respectively in four pressure rolls in the set 24. Preferably, the pressure rolls 24 and subsequent reduction rolls are power driven as shown, for example, by equipment such as illustrated in FIGURE 5 in connection with rolls 24. For convenience of reference, the clad rod leaving rolls 24 and passing through the balance of the line shown in FIGURE 1 for operations thereon is given the reference numeral 120, in which the core is 12 and the cladding is given the reference numeral 26.

In FIGURE 5, an electric motor 28 acts as a common power source. Motor 28 is connected by a flexible coupling 29 to a shaft 30 on which one of the pressure rolls 24 is fixedly mounted. Shaft 30 may be provided with a bevel gear 31 and a spur gear 32 for respective connection to a bevel gear 33 and a driven spur gear 34. The gears 33 and 34 are keyed to stub shafts 35 and 36 to drive two of the remaining rolls 24 at identical speed.

Shaft 36 is also provided with a fixed bevel gear 37 which engages a further bevel gear 38 on a stub shaft 39 to drive the remaining roll 24 at the same speed and in the same direction, suitable bearings for all of the rolls being provided therefor in machine 18 in the line shown in FIGURE 1. Thereby, pressure rolls 24 not only density the cladding metal to an extent which may even slightly reduce the diameter of core 12 somewhat, but they also move substantially at the speed of movement of core 12 which is under tension, thereby avoiding relative movement between the cladding 26 being pressed by them onto the core 12. The adjoining mating edges 40 of the rolls 24 are preferably beveled to meet and inhibit the formation of longitudinal fins or fiash" on the outside surface of the clad rod 12a as it passes through pass 23 of the pressure rolls 24. As to such small amounts of fin formation as may occur in compacting rolls 24 and subsequent pressure rolls, provision for trimming such fins off preferably should be made prior to the entry of the clad rod into any subsequent cross-sectional area reduction mill in the continuous line.

The bimetallic rod 12a comprising core 12 and cladding 26 on the delivery side of rolls 24 has adherency between core and cladding which is less than that desired for the end use handling to which it will be subjected. Adhcrency among the cladding particles is promoted by heating in a furnace 41 which is shown as having an electrical induction heating coil 42 therein. Leads 52 of coil 42 may be connected to a suitable source and character of electric power for the induction heating service to be performed by the coil. Clad rod 12a passes through the center of coil 42, in the course of its continuous movement, at a suitable speed, the heater 41 being long enough to generate the desired temperature for the desired period of time in the cladding metal 26 on clad rod 1211. A clad rod like rod 12a moving at a speed of about feet per minute may be caused to reach a temperature of about 1100 F. by an induction heater using current having a frequency of about 20-00 to 3000 cycles per second. It will be realized that in matters of this kind, some compromise of temperature relative to time, and vice versa, may be effected without departure from our invention. A controlled atmosphere of a generally non-oxidizing or somewhat reducing character may be maintained in heater 41 and in any other location that may be utilized in a practice of this invention where time, temperature, or other factor warrant to inhibit oxide formation. The controlled atmosphere may be a nitrogen-hydrogen mixture (e.g., up to 10% hydrogen with the balance nitrogen) or hydrogen or helium or other non-oxidizing gas.

Temperature equalization of clad rod 12a in heater 41 may be provided by a soaking section 43 before entering a rolling mill 44. Mill 44 may be provided with a further set of power-driven pressure rolls 24a preferably having a modified round pass of lesser diameter than pass 23 to effect a hot rolling reduction of the cross-section of rod 12a for bonding purposes, any single such hot rolling reduction preferably not being below about 10% of the clad rod cross-sectional area entering the pass of rolls 24a. At the exit of mill 44, the hot rolled clad rod 12a has the aluminum cladding 26 directly bonded to the steel core 12, the cladding itself being practically non-porous, smooth and continuous such that when the clad rod is bent cold rather sharply, such cladding will neither crack nor break nor separate from the core. Dependent upon metallurgical properties desired in the clad rod, a further temperature treatment of rod 12a exiting from mill 44 may take place in a temperature adjustment facility 45 before rod 12a enters mill 46 and a second set of preferably power driven pressure rolls 24b to effect a further reduction in the cross-sectional area of rod 12a in a maner to avoid causing relative wiping movement of cladding and core or any tendency to extrude the cladding relative to such core. Mufiles or hoods 47 may be provided for clad rod between respective items of equipment whenever the use of a controlled atmosphere is indicated as hereinbefore set forth.

Upon leaving mill 46, the rolled clad rod 12a is cooled in a cooling device 13 and may be passed into a cold rolling mill stand 48. Facility 13 may have cooling tubes located therein or a cooling fluid may be circulated through its interior, such cooling fluid having a composition which is non-reactive relative to clad rod 12a, to bring the temperature of clad rod 12a down to a desired lower rolling temperature before the rod enters mill 48. In mill 48, further sets of pressure rolls 24c, preferably power driven like the rolls 24, but with progressively smaller circular passes therethrough, are provided. It will be recognized by those to whom this invention is disclosed that the peripheral speed of respective sets of pressure rolls in a continuous line practice of this invention will be coordinated for such continuous pressure rolling action.

The order of reduction effected by each set of rolls 24c in the embodiment illustrated in FIGURE I preferably is about of the entering cross-sectional area of the clad rod entering each such set of rolls 24c, until the clad rod is of the desired diameter for the subsequent purpose it is to serve. Such lower temperature rolling may be used to obtain suitable drawing characteristics of the rolled clad rod 12a for certain product applications. Provision may be made for intermediate heating of the clad rod if needed to counteract any tendency toward a lessened softness or ductility because of its being rolled or drawn.

A practice of this invention as described yields a metallurgical bond between the core metal 12 and the cladding metal 26 as schematically illustrated in FIGURE 7 where the interface 49 discloses the presence of a coherent bond better than a mere mechanical bond, but yet one in which there is an absence of any significant quantity of brittle aluminum-iron compound (in the case of aluminunrclad steel) and an absence of deleterious extensive diffusion causing brittle phase formation at such interface. The bond at interface 49 is adherent enough so that when reduced clad rod 12a on reel 14 is cold drawn to wire size, it has been discovered that the radius of the core and that the radial thickness of the cladding thereon will both decrease while the cladding continues to generally uniformly surround that core during such drawing. The finished bimetallic article will therefore be in a form, in the illustrated practice under discussion, of an aluminurnclad wire with a steel core suitable for electric power, telephone, and signal and other electrical and mechanical uses.

A further practice of our invention is schematically illustrated in an equipment line shown in our FIGURE 6 of the drawings. Therein, parts corresponding generally in structure and in functioning to equipment shown in FIGURES 1 to 5 are provided with the same reference numerals with the addition of a prime factor thereto. In FIGURE 6, a metallurgically clean ferrous rod 12' is fed vertically downwardly in self-centering relation through a hopper 19' containing powdered metal 50 to serve as a cladding metal for rod 12. Hopper 19' feeds powder 50' into forming tube 22' by gravity to uniformly and entirely surround rod 12' as both enter the nip of the pressure rolls 24". The clad rod 12a immediately upon leaving rolls 24' may be passed through an induction heating coil 42' and through a hot-reduction rolling mill 44 to complete the densifying and bonding of the cladding to the rod core. A hood 41' may be provided around coil 42' and rolls 24, suitable openings 51 being provided in hood 41' for the circulation of a non-oxidizing controlled atmosphere within it. When clad rod 12a leaves coil 42', it is led in the form of a catenary loop 53 through a pit 54 below plant floor 55', to enable the rod 12a to enter a horizontal line of equipment for reduction rolling. Thus, rod 12a engages a guide roller 56 of a large diameter as red 12a leaves pit 54 and enters a temperature adjustment facility 45' in a horizontal direction before passing through mill 46. After leaving mill 46', red 12a" may move through a mufiie 47 and through a second rolling mill 46a for a further reduction in the diameter of clad rod 12a". In leaving 46a, rod 12a may enter a cooling chamber 57 with a non-oxidizing controlled atmosphere therein, which itself may be the cooling medium, to bring the temperature of clad rod 12a" to a suitable temperature before it exits therefrom and is wound up on a windup reel 14'.

It will be recognized by those skilled in the art to whom this invention is disclosed, that some variation in the order of steps of a new practice of our invention as disclosed herein can be accommodated as in the case of having a rolling reduction step prior to a heating step as discussed in connection with heaters 41 and 41; that heating may be caused to occur by means other than an induction heating coil; that powdered metal may be applied to a core by a positive feed or by having more than one machine like machine 18 in tandem, whether in vertical or in horizontal arrangement; that a heating step may be interposed between one or more of the reduction steps or of drawing dies; that the clad rod issuing from the last rolling mill may be led directly into a first set of drawing dies or elsewhere instead of being taken up on a reel like reel 14 or 14'.

The disclosure herein which has been described in connection with the production of a composite aluminumsteel rod or wire is also applicable to the production of such elongated bimetallic articles having copper as a cladding metal supplied initially against the core in the form of powdered copper pressed into intimate contact with every portion of the core surface, as taught above. In the case of such copper-clad articles produced hereunder, the temperatures involved are higher, copper having a higher melting point than aluminum. Thus, a rod with such copper cladding initially applied as pressed powder directly to a ferrous core may be heated, in a furnace corresponding to furnace 41 or 41, up to a temperature of from about 1800" to about i900 F. in a non-oxidizing controlled atmosphere; and the hot rolling reduction steps in mills like mills 44 or 46 may take place at a temperature of from about 1600 to about 1900 F. An annealing step at 1300 F. may be interposed following any hot or cold rolling reduction step or die drawing step where the eventual service for the product indicates somewhat greater softness or ductility may be desirable. Again, as in the case of the aluminum-ferrous bimetallic members produced by this invention, conditions are preselected such that the bond between the ferrous core. and copper cladding is a metallurgicai bond. In the case of copper, a bond is obtained that is more than a mere mechanical bond with as a practical matter some diffusion of the respective metals into one another being permissible short of the formation of a deleterious zone or layer, since no harmful brittle compound as such is formed at the interface.

As an example, a steel rod of AISI Cl020 composition having a diameter of A of an inch was press-roll clad to a diameter of about 9.42 of an inch with Charles Hardy type A electrolytic powdered copper metal and then heated up to 1900 F. in a hydrogen atmosphere. Thereupon, the temperature of the clad rod was brought to about 1690" F. in a helium atmosphere and reduced by hot rolling through pressure rolls to a diameter of 9.295 of an inch. The product was then drawn through several dies to a final diameter of 0.096 of an inch to successfully provide a copper-clad steel wire of that diameter; an intermediate annealing having been performed on the wire being drawn at a temperature of 1300 F. in a non-oxidizing controlled atmosphere (10% hydrogen H nitrogenhN when the diameter of the wire was 0.114 of an lIlC Comparably, aluminum-rich and copper-rich powdered metal mixtures and like metals may be applied to ferrous and other cores for the production of elongated bimetallic members in which the core (whether in rod, wire or other form) may, if desired, be entirely surrounded by a cladding metal having a lesser tensile strength or greater corrosion resistance, or both, than the core material, in a continuous or in a non-continuous operation as may be desired, with the production of a bond between the cladding and core such that the articles so produced may serve suitably in fields where bendability, elasticity, ductility and the other properties of such materials are desirable. Moreover, various generally non-oxidizing atmospheres or atmospheres on the reducing side may be utilized in the above illustrated practices of this invention. And, while this invention has been described principally in the light of the production of clad rod and clad wire, it will be appreciated that our invention is applicable to the production of clad flat and cylindrical base shapes irrespective of whether or not such cladding is applied so as to wholly enclose the cores or bases of such shapes. Moreover, the term rod when used alone shall be deemed to include wire.

Preferred Embodiment A preferred embodiment of our invention is illustrated in the form of the continuous cladding line shown in FIG- URES 8 to 21, inclusive, for the production of a bimetallic product such as aluminum clad steel rod in which the aluminum cladding is metallurgically bonded to the ferrous core. As used herein, the term rod includes material of rod and wire gauge sizes as well as material of round or other cross-sectional shape. The metals discussed include ones of like properties including alloys of the metals named, respectively. In the product made by the preferred embodiment, the core is uniformly clad and the cladding is very dense and virtually wholly free of voids; the cladding is continuous, is adherent to itself and to the core and is of relatively uniform thickness around the core. Such product is producible by the preferred embodiment at commercial production rates with a minimum of manpower and expense and fully meets practical and commercial test, service and use requirements for such a product. The thickness of the cladding further can be varied relative to the cross section of the core within the capacity of the particular equipment employed to produce a given final size of clad rod.

In the general arrangement of the preferred line shown in FIGURE 8, there is a flipper-type payout reel having diametrically oppositely extending arms 101 supporting an active coil 102 of ferrous rod being utilized as the core material for the clad rod product then being made and an at ready coil 103 on the other arm 101. A butt Welder 104 is located adjacent one side of reel 100 and enables the trailing end 102a of coil 102 to be welded to the leading end 1030 of the ready coil 103 as core rod 105 continues to be pulled from coil 102 into the mechanism shown in FIGURE 8. When the ends 102a and 103a are welded together, any flash or offset at the weld joint is ground off or otherwise removed and the weld may be annealed if desired in the welder itself as by a manual post-weld anneal control. Core rod 105 is pulled in the direction of the arrow into a straightener 106 having a powered bank of pinch rolls 107 and two further banks of straightening rolls 10-8 in two planes so that the rod issues from straightener 106 in a straight line which is maintained through the apparatus as far as the capstan roll mechanism 109.

A wheel thrown abrasive metal grit machine 110 mechanically cleans the core rod to place it in a metallurgically clean state as it passes through machine 110 between entry guide roll 111 and exit guide roll 112, and an elevator 113 returns grit above a selected size to a supply hopper 114, finer particles and dirt being removed and deposited outside. The core 105 issuing from machine 110 has an unsmooth somewhat rough lit texture surface free of foreign matter including carbonaceous smut. Other methods of descaling and cleaning, including wire brushing, may be utilized instead.

The metallurgically clean core rod is then pulled through an applicator mechanism 115 where the green cladding metal, such as atomized (e.g., Alcoa No. 125) aluminum powder, is fed by positive means into a predetermined diameter around the core rod immediately prior to its entry into a roll compacting mill 116. One suitable aluminum powder for the illustrated equipment would have a particle distribution as follows.

U.S. Standard Sieve:

Mesh- Percent retained On 20 About 1 max. On 40 About 10 max. On 70 30 to 50. On 140 35 to 55. On 200 About 10 max. Through 200 About 0.5 max.

A cladding powder bin 117 is provided adjacent the applicator mechanism and periodically replenished. A vibratory feeder 118 is connected to the bottom of bin 117 and operated to maintain a reservoir of such cladding powder in a hopper 119 at the top of applicator mechanism 115. A vibrator 120 may be attached to the front wall of hopper 119 to facilitate the passage of cladding powder into a positive powder applicator 121.

Applicator 121 is fixed in brackets 122 rigidly secured to a main bracket 123 and to the face plate 124 of compacting mill 116. Bracket 123 is also secured to plate 124. A hollow arbor 125 in applicator 121 is drilled for the axial passage therethrough of core rod 105. A helical screw 126 is secured to the exterior of arbor 125 to force cladding powder uniformly around the surface of core rod 105 as it enters the bite of the closed circular roll pass defined by four Turks-head rolls 127 in mill 116. In going through such pass, the powder cladding on rod 105 is compacted forming a green clad rod 105a in its green or compacted form. The pressure in the pass of mill 116 is preferably sufficient to densify the cladding powder and possibly slightly reduce the diameter of the ferrous core by a few thousandths of an inch. The compacting by mill 116 will produce a density in the cladding powder which is greater than 98% of the density of high-purity wrought aluminum. Longitudinal fins formed at the parting line of the mating edges 165 of the power-driven rolls 127 are milled off by a fin remover 128 as the compacted clad rod 105a leaves the mill rolls of stand 116.

The metal work line along which the green clad rod 105a passes continues through an induction heater machine 129, entry guide rolls 130 and exit guide rolls 131 being mounted on the front and back of the induction heater stand supporting an induction heater coil 132 in concentric relation to the work or pass line. In the induction heater, the rod 105a is very quickly heated through the cladding and interface between the core and cladding to a temperature not less than 900 F., or higher, and moves on directly into a hot reduction mill 133. In mill 133, a further set of powered Turks-head rolls 134 are provided with a further wholly closed pass which bond cladding and core, reduce the clad rod and slightly flatten each quadrantal portion of the surface engaged c thereby. The power-driven rolls 134, like the powerdriven rolls 127, are rotated at a speed so as to exert no drag or force tending to shift the cladding relative to the core of the clad rod going through the respective pass thereof and, indeed, such power-driven rolls may somewhat aid the movement of the clad rod through such respective pass. A fin remover 135 shaves the slight longitudinal fins produced at the corners in the pass through the rolls in the parting planes defined by the engaging mating edges In moving through the pass of mill 133, the hot compacted clad rod 105a has the aluminum cladding and ferrous core brought into more intimate contact and achieves a metallurgical bond between the aluminum and steel without the production of any continuous interface layer of aluminum-iron compound or any substantial formation of that compound. Such traces of compound as may appear are not detrimental. In mill 133, the cross-sectional area of the clad rod is reduced preferably not less than to a maximum of about 25%, both the aluminum cladding and ferrous core sharing in such reduction.

The bonded clad rod leaving [in remover 135 goes to a finish sizing rolling mill 136 having unpowered rolls 137 therein preferably rotated 45 around the axis of the rod line relative to the position of the rolls in mills 116 and 133. Thereby, the bottom of the grooves in the rolls 137 encounter the definned corners of the bonded clad rod leaving mill 133 and provide a final flattening of those corners and a finish rounding of the surface of the clad rod. Substantially no reduction is made by the roll pass in mill 136. The rod 105 and clad rod 105:: do not appear to twist appreciably in passing through the respective mills which preferably are placed closely together thereby economizing in space. As the round bonded clad rod leaves mill 136, it is still quite hot and a cooling water spray mechanism 138 is used to reduce the temperature of the cladding thereon at least to a temperature above the boiling point of water, preferably about 250 to 300 F., when water is such coolant so that the rod is dry by the time that it makes its first wrap around the far wheel of capstan 109.

Capstan 109 is provided with a drive wheel 139 and a driven wheel 140. The drive wheel 139 is powered by an adjustable speed drive 141. The finished clad rod from mill 136 first engages the rear side of wheel 140 and then engages the forward half of wheel 139 and then the rear side of wheel 140 again in the desired numbers of wraps before passing on to a coiler mechanism 142. Such wraps around the capstan wheels 139 and 140 provide the desired tension in the work line, avoid slippage and cause wheel 140 to turn. The surfaces of the capstan rolls 139 and 14!] may be grooved if desired for loop separation, guidance and traction. The speed of the cap stan is synchronized as will be understood by those to whom this invention is disclosed with the speed of the power-driven rolls in straightener 106 and the mills 116 and 133. Tension supplied by the capstan furnishes pulling force required to move the rod line in the direction of the arrows shown in FIGURE 8 at the selected speed.

The finished clad rod 165a then passes from its last engagement with capstan wheel 139 to a driven coiler 142 where the rod is engaged by pinch rolls 143 controlled by an adjustable screwdown 144. The clad rod then passes between guide rolls 145 and beneath a deflector roll 146, the vertical height of which may be adjusted by a manual control 147 to place a predetermined curvature in the steel core of the clad rod 105a generally equal to the desired diameter of the coil. A laterally extending mandrel 148 is provided and at the start of an operation the free end of a rod is threaded between guide rolls 149 and passed between a shear block 150 and a cylinder operated shear knife 151 which is electrically or otherwise timed to sever the finished clad rod after the desired number of coil loops have been made. The curvature in the clad rod produced by the deflector roll 146 is sufficient to keep the leading end coiling around the mandrel 148 in a helical outwardly traveling manner until the coil is severed by the shear as aforesaid, whereupon the next coil begins to form, shoving the earlier coil or coils outwardly on the mandrel. If desired, the mandrel 148 may be powered so as to turn in a coiling direction as indicated by the arrow thereon.

FIGURES 9 to 14, inclusive, show the cladding mill 116 in greater detail, together with the applicator mechanism 115 and fin removed 128 associated therewith. The front end of the arbor 125 is keyed to a sprocket 152 which is rotated by an adjustable speed motor-reducer set 153 connected to sprocket 152 by a chain 154 in a direction to cause the screw thread 126 to feed cladding powder in a rearward direction toward the tip of the applicator. Arbor is provided with a thrust collar 155 keyed thereto which engages a bearing 156 secured in casing 121. Thrust roller bearings 157 rotatably support the entry end of the shaft of arbor 125 which terminates at 158 where it is keyed to sprocket 152.

Cladding powder enters the interior of casing 121 through an opening 159 in communication with the bottom of hopper 1 19, such powder filling the space around helical screw blade 126 inside of the interior of casing 121 forwardly of collar 155 and exteriorly of arbor 125. A relatively short, blunt, frusto-conical tip 160 having an axial passage therethrough is fastened to the rear end of arbor 125. Tip 160 has a tapering exterior surface generally parallel, or slightly divergent, relative to the interior surface of a nozzle member 161 secured to the front of casing 121. The space between the exterior of tip 160 and the interior of nozzle 161 does not constrict the crosssectional area of the cladding powder being forced through by rotation of the screw 126 at a predetermined speed relative to the speed of the moving rod 105. Nozzle 161 is provided with a throat portion 162 between the discharge end of tip 160 and its own discharge end in which the cladding powder is firmly pressed by the applictaor uniformly and concentrically around the rod 105 substantially just as such powder cladding and core rod enter the bite of the compacting circular closed pass 163 through the four-axis Turks-head rolls 127. By means of thin, tapered ribs 164 extending rearwardly in the respective planes of the mating surfaces 165 between the respective rolls 127 and in very close proximity thereto, the escape of cladding powder from the bite of pass 163 into the nip between adjoining mating faces 165 moving toward engagement with one another is greatly inhibited. Hence, formation of radially upstanding longitudinal fins at the intercardinal points around the circumference of the green compacted clad rod 105a is materially reduced or prevented. The rearward bracket 122 on plate 124 acts to center that end of applicator 121 in alignment with the axis of pass 163.

As the green clad rod enters the bite and pass of rolls 127, it is compacted and the cladding densified at ambient temperature to form the compacted stage of clad rod 105a prior to its entry into heater 132. The T urks-head rolls 127 have mating edges or faces 165 which form diagonal parting planes along the four intercardinal points relative to the axis of the rod line and the planes of the respective rolls 127. The circular pass 163 is formed by the four quadrantal rolling grooves 166 in the rolls 127. Each roll 127 is provided with an axle 167 rotatably mounted in a slide 168 in a rigid frame 169 secured to the transverse vertical plate 116a of compacting mill 116. The frame is also mounted on legs 170 fixed thereto and in turn fixed to the base 171. Such frame 169 and transverse plate 116a are provided with suitable cutout portions, front and rear, for the projection there through as shown of front and back portions of the respective rolls 127. Rearwardly extending wind plates 172 are respectively secured to the sides of plate 116a and base 171 to further rigidify the roll stand. One of the slides 168 is prepositioned and each of the other slides 168 is engaged by a threaded screwdown rod 173 and manually movable by a wrench for the squared ends 174 in the illustrated embodiment, each screwdown having vernier scale 175 to provide information as to the precise setting selected when the mating faces 165 are brought together around the axis of the rod line along which the work passes.

Roll stand 116 is driven by an adjustable speed motorreducer set 176 through a coupling 177 and parallel drive shafts 178 and 179 interconnected by gears 180 keyed to the respective shafts. Only the vertical plane rolls in 11 mill 116 are power driven, with the horizontal plane rolls 127 being driven by friction received from the respective top and bottom plane rolls between the mating faces at the parting plane.

In FIGURES l and 11, respective lubrication and scraping means are shown for a roll in cladding mill 116 as illustrative of such lubrication and scraping means applicable to each roll in that mill and to each of the Turks-head rolls in mills 133 and 136-. Thus, the surfaces of the roll parting plane faces 165 and of the roll grooves 166 are each lubricated by a felt pad 181 held by a holder 182 pivotally supported at 183 to a lug 184 on the face 124 of frame 169. A pressure adjustable spring 185 engages the outer end of the holder 182 to cause the pad 181 to press against the roll surface mentioned. In cladding mill 116 it has been found that a continuous film of stearic acid is a suitable lubricant, such lubricant being wiped on the rolls as a solution of stearic acid and a volatile solvent such as trichloroethylene which solvent evaporates readily. In the case of rolls 134 and 137 respectively in mills 133 and 136, it has been found that motor oil is a suitable lubricant and all of the lubricants used may be fed to the pads by oil cups or drip devices, or otherwise. Other lubricants may be used and function in the base of aluminum cladding to prevent sticking or galling of the cladding material relative to the roll surfaces. In addition, scraper blades 186 are attached to an angle holder 187 pivotally mounted in a lug 188 secured to the back of plate 116a. An adjustable spring 189 presses the outer end of holder 187 to press blade 186 into contact with a mating face 165, there being one such scraper blade for each such mating face of each roll to remove any aluminum fragments which might otherwise tend to accumulate upon those parting surfaces.

A table 190 is secured to base 171 of mill 116 between the wings 172 to support the fin remover 128 fastened thereto. A rear end view of fin remover 128 in somewhat larger detail is shown in FIGURE 13. As compacted clad rod 105a issues from the roll pass of mill 116, it is likely to have slight longitudinal and radially extending fins along the northeast, southeast, southwest and northwest points considering north as a vertical line originating at and extending above the axis of the metal line along which rod 105a is passing. Such fin remover has a base 191 for its milling cutters, a milling tool 192 for one pair 180 degrees apart of the four fins and a further milling tool 193 in differently oriented r juxtaposition thereto for the other pair of such fins. The milling tools are mounted respectively on plates 194 at transverse 45 and 135 degree slopes as seen in FIGURE 13. Each has a motor 195 coupled to a drive gear 196 which is in engagement with a driven gear 197. Both gears are connected to shafts, the outer ends of which are respectively provided with milling cutters 198 and 199 respectively. Such reference numerals in FIGURE 13 are applied to subassembly 193 which is identical to subassembly 192 at right angles thereto. The respective milling cutters rotate so as to engage the respective fins to be removed in a direction contrary to the direction of movement of the metal line, the spacing between the respective milling cutters being adjusted by the spacing of thrust bushing held in an end plate 200 to clear the regular periphery of the compacted clad rod 105a while removing such fins at the base thereof. Upon leaveing the fin milling cutters, the definned compacted clad rod is guided between a pair of steadying guide rolls 201 se cured to a support 202 fixed to base 191.

A cladding thickness gauge may be provided on the discharge side of fin remover 128 to continuously compare the thickness of the cladding at different points around the periphery of the compacted clad rod. In the case of aluminum cladding which is non-magnetic,

such would form a gap in a magnetic circuit including the steel core so that a change in the thickness of such aluminum cladding would cause a measurable change in the reluctance of such magnetic circuit. Such magnetic circuit would be connected to an indicating meter to show any variation from the selected cladding thickness as well as non-uniformity around the periphery of the core.

As the definned compacted clad rod leaves mill 116 and fin remover 128, it passes directly to and through an induction heater mechanism 129, steadying guide rolls and 131 being mounted on standards 203 and 204 at the respective ends of equipment 129. The induction heater 132 as shown comprises a straight envelope coil of copper tubing through which water is circulated for cooling purposes. The tube is connected to a motor generator set 205 to supply sutficient alternating current power to the induction heater coil at a frequency in the neighborhood of 2,000 to 3,000 cycles per second, or higher. The alternating magnetic field generated induces currents within the compacted clad rod and has sufficient penetration to reach the interface between the cladding and the core material resulting in rapid heating at the interface to a temperature kept below the melting point of the cladding material. For powdered aluminum cladding around a steel core, the preferred interface temperature is in the neighborhood of from 1000" F. to 1150 F. A broader range extends from about 900 F. up to a temperature not exceeding 1200 F. The heated rod exiting from heater 132 radiates spectrum waves which pass in timed sequence through the aperture in a rotating shutter 225 and fall upon a thermistor bolomcter mechanism 226 interconnected to the electrical circuit of heater 132 to vary the power input thereto sufiiciently to maintain the temperature of rod 105:: leaving heater 132 at a preselected operative level. The desired heating occurs in a matter of seconds. As will be understood by those having ordinary skill in the art to whom this invention is shown, some compromise is possible to achieve the selected temperature utilizing various electrical power, frequency and heater dimensions in correlation with the selected speed, size and character of the clad rod to be produced.

As the heated clad rod leaves the induction heater assembly 129, it passes directly to the proximate hot reduction mill 133 shown in greater detail in FIGURES 15 and 18. That mill equipment has parts which correspond generally in construction and function to parts of cladding mill 116 and such are marked with the same reference numerals with the addition of a prime accent thereto. In hot reduction mill 133, the frame 169 is secured to transverse support plate 133a (corresponding in function to plate 116a) and the powered rolls 134 are again the top and bottom vertical plane rolls with the horizontal plane rolls 134 being driven by friction transmitted from the adjoining mating faces of the vertical plane rolls to the engaged mating faces of the horizontal plane rolls respectively. Such mating faces are also shown in FIGURE 19.

Each of the hot reduction rolls 134 is provided with a roll pass groove 206 of a different contour and size from that of the rolls 127 in the compacting mill. Thus, in the closed pass 207 of the rolls 134, the are of each roll groove between the bounding parting planes defined by the engaged mating faces is slightly flattened in each quadrant controlled by a particular roll pass groove relative to the outline of a true circular quadrant, as appears in FIGURE 19. Moreover, in passing through pass 207 the cross-sectional area of the heated clad rod 105a is reduced in the range from about 5% to about 25% dependent upon temperature and the respective properties of the cladding and core materials in the clad rod. In hot reduction mill 133, metallurgical bonding of the cladding to the core is obtained. In the case of aluminum powder cladding on a ferrous core, such metallurgical bonding appears to achieve some diffusion of aluminum into steel without the production at the interface between those metals of any significant quantity of relatively brittle aluminum-iron compound or of any continuous layer of such compound. Further, there appears to be recrystallization of the original aluminum powder particles changing grain sizes and boundaries to a significant extent and yielding an adherent non-porous cladding metallurgically continuous and bound to the steel core. Such product is also suitable for cold wire drawing when the steel core has requisite elongation qualities. Hot reduction mill 133 is also provided with lubricators and scraper blades as in the case of the cladding mill 116 with the further provision that in the case of mills 133 and 136 such lubricaiton may be achieved instead by pumping a stream of water soluble cutting oil into the entry bite of the rolls 134, or rolls 1387, or both.

Such longitudinal fins as are produced in mill 133 extend from the periphery of the hot reduced clad rod northeast, southeast, southwest and northwest for a short distance along the parting planes shown in FIGURE 19. Such fins preferably are removed by the fin remover 135 mounted on a crossplate 208 secured between and to the Wings 172 so that the fin remover 135 surrounds the axis of the metal line along which clad rod 105a is passing. That fin remover is illustrated in more detail in FIGURES 16 and 17. It comprises two semicircular knives 209 on slide plates which, when clamped together in holder 210 centered in a centering ring 211 around a central opening in plate 208, present shaving knife edges 212 toward the oncoming hot reduced clad rod which passes through a central bore 213 formed by the two knives and an opening 214 in holder 210 as the fins are removed from the periphery of rod 105a. The sides of the bore 213 diverge slightly in the direction of movement of the hot reduced clad rod for relief. The slide plates of knives 209 are movable in guide slots 215 which maybe centered by the adjustment screws 216. If desired, the tin remover of FIGURES 16 and 17 may be utilized to defin the compacted clad rod exiting from mill 116 in place of the milling cutter fin remover 128.

The definned hot reduced clad rod passes in the illustrated preferred embodiment to the proximate finishing mill 136 where the modified round produced by pass 207 is then reshaped by the circular round pass defined by the four Turks-head rolls 137. In mill 136, parts thereof corresponding generally in structure and functioning to parts of prior mills are provided with the same reference numerals with a double accent added thereto. In finishing mill 136, the frame 169" is rotated about the axis of the metal line and roll pass through an angle of 45 degrees, such frame being secured by bolting to a transverse support plate 136a secured to base 171" and Wings 172". Support brackets 217 secured to plate 136a assist in maintaining frame 169 in precise operative position. As shown, the rolls 137 are of somewhat smaller diameter than the diameter of the compacting rolls 127 and hot reduction rolls 134. The circular quadrantal groove 218 in rolls 137 has the bottom thereof engaging a respective intercardinal corner of the definned hot reduced clad rod 105a resulting in the finish shaping of that rod to a finish round of the desired end dimension. In the preferred embodiment, no appreciable change is produced in the cross-sectional area of the clad rod as it goes through the pass of the rolls 137. These rolls, moreover, are not driven but receive their movement from the pulling therethrough of the clad rod in the course of the operation. Further, the rolls 137 are provided with narrow contacting mating faces 165" in vertical and horizontal parting planes. Lubrication and scraper blade means are provided for mill 136 in the same way as they are for mill 133.

The cladding of the finished clad rod 105a is still relatively hot as it leaves the rolls 137. In the case of a cladding made of a softer metal like aluminum, tcmpen atures above about 300 F. offer relatively greater opportunity for deformation or scoring of the cladding. In the preferred embodiment of FIGURES 8 to 21, such a cladding is cooled and made relatively harder by a longitudinally extending spray pipe 138 supplied by a communicating pipe 219 with a coolant, such as water 229, sprayed by pipe 138 onto the clad rod 105a issuing from mill 136. A drain trough 221 having an outlet 222 is supported between wings 172" on base 171" by a shelf 223 and legs 224 secured thereto. In the case of finished aluminum clad steel rod, such coolant is evaporated from the surface of the rod before the finished clad rod comes in contact with the capstan mechanism 169, thereby promoting traction and control of the tensioning in the metal line by such capstan. Upon leaving the capstan mechanism 109, the finished clad rod is coiled as described above ready for use as it is, or for further treatment including wire drawing.

As an example only and without limitation of this invention thereto, the preferred equipment may be used to make aluminum clad steel core rod in a continuous operation as follows. The starting materials may be coils of steel rod having a diameter of of an inch and, say, a (3-1043 composition, on the one hand, and atomized aluminum powder such as Alcoa No. 125, on the other hand. In the applicator 121, such cladding powder is applied around the cleaned steel core to increase the over-all diameter of the core and cladding to about 0.44 of an inch by compacting in the pass of mill 116. The compacted clad rod is pulled along at a speed of about 30 feet per minute and after having been so compacted and definned, it enters induction heater 132 through which it is passed in about 7 seconds at that speed in the course of which it is heated at the interface as nearly as can be determined to a temperature between about 1050 F. and 1100 F. Immediately following such heating, it is passed through the roll pass of hot reduction mill 133 where it is reduced in cross section from about 15 to 20%. In the hot reduction mill 133, metallurgical bonding with but scattered traces of aluminum-iron compound takes place with further densification and apparent recrystallization of the cladding material. The hot reduced clad rod is then definned and made into a finish round by mill 136 without significant change in the cross-sectional area. The finish diameter of such clad red in this example is about 0.4 of an inch with the steel core diameter being about 0.345 of an inch.

Thus, aluminum clad steel rod can be produced by the equipment of the preferred embodiment with the core and cladding concentric, with the core and cladding of desired respective cross-sectional areas and thicknesses, with the cladding continuous, non-porous and metallurgicaliy bonded over the interface to the core, without any continuous layer or detrimental amount of brittle aluminumiron compound at the interface and with desirable properties of the core and cladding metals preserved. Further, such new product can be produced continuously in the open air without having to take precautions against oxidizing of the metals involved and at desirable speeds upwards of twenty-five feet per minute in any length desired. Employment of the principles of this invention are utilizable also with respect to cores and claddings of different selected thicknesses and different selected materials including those, e.g., coating or cladding metals which may have a relatively higher strength than the core metals to be used therewith respectively. Still further, while the preferred embodiment is but one optimum arrangement for economy of labor, materials, equipment and space, it will be understood that the principles, stages and steps thereof may be engaged in in somewhat different order, or on a more extended or contracted basis, or under varying conditions, without departing from the teachings of our invention set forth herein.

Various other modifications may be made in the dis- 15 closures herein without departure from the spirit of this invention or the scope of the appended claims.

We claim:

1. In a method of cladding a steel rod or wire core with powdered aluminous metal, the steps comprising, in combination, pulling said core coaxially through an applicator tube, supplying powdered aluminous metal to said tube to fill it around said core substantially until said core and cladding enter a pass in a set of pressure rolls, roll pressing said cladding into intimate compaction against the surface of said core in said pass to a density approaching that of solid metal, heating and rolling said pressed clad core at a temperature between about 950 F. and at sufficient pressure and not in excess of about 1180 F. to cause said cladding to become coherent and to adhere to said core with a metallurgical bond substantially free from compound forming diffusion of the respective cladding and core metals into one another at the interface, and further rolling the clad rod.

2. In a method of cladding a steel rod or wire core with powdered aluminous metal, the steps comprising, in combination, processing said core to make it metallurgically clean, pulling said core coaxially through an applicator tube, supplying powdered aluminous metal to said tube to feed it around said core under a positive force substantially until said core and cladding enter a compacting pass in a set of pressure rolls, pressing said cladding into intimate compaction against the surface of said core in said pass to density approaching that of solid metal, rapidly heating and rolling said pressed clad core at a temperature between 900 F. and 1200 F. and at sufficient pressure to cause said cladding substantially in an unmelted state to become coherent and to adhere to said core with a metallurgical bond substantially without extensive diffusion of the respective cladding and core metals into one another at the interface and, further, without formation of any substantial, continuous layer of brittle compound between said cladding and core.

3. In a method of cladding a ferrous core with powdered aluminous metal, the steps comprising, in combination, moving said core substantially longitudinally through an applicator, positively feeding powdered aluminous metal to said applicator to put said aluminous metal on said core, passing said core and cladding through a compacting pass in a set of pressure rolls, directly roll pressing said cladding into intimate compaction against the surface of said core in said pass to a density approach ing that of solid metal, rapidly heating and rolling said pressed clad core at a temperature in the neighborhood of from about 1000 F. to about 1150 F. and at sufficient pressure to cause said cladding to become coherent and to adhere to said core with a metallurgical bond substantially free from aluminous metal-iron compound.

4. In a method of cladding a steel rod or wire core with powdered cupreous metal, the steps comprising, in combination, processing said core to make it metallurgically clean, pulling said core axially through an applicator tube, feeding powdered cupreous metal to said tube to fill it around said core substantially until said core and cladding enter a pass in a set of pressure rolls, roll pressing said cladding into intimate compaction against the surface of said core in said pass to a density approaching that of solid metal, rapidly heating and rolling said pressed clad core at a temperature between about 1600" F. and not in excess of about 1900 F. and at suflicient pressure to cause said cladding substantially in an unmelted state to become coherent and to adhere to said core with a metallurgical bond without extensive diffusion of the respective cladding and core metals into one another, and further rolling the clad rod at a lower temperature.

5. In a method of cladding a ferrous core with powdered cupreous metal, the steps comprising, in combination, pulling said core coaxially through an applicator tube, supplying powdered cupreous metal to said tube to feed it around said core under a positive force, passing said core and cladding through a compacting pass in a set of pressure rolls, roll pressing said cladding into intimate compaction against the surface of said core in said pass to a density approaching that of solid metal, heating said pressed clad core up to a temperature in the neighborhood of 1900 F. but below the melting point of said cupreous metal, and rolling the clad rod substantially at said temperature sufiicient pressure to effect a reduction in the cross-section of said clad rod and to cause said cladding to become coherent and to adhere to said core with a metallurgical bond.

6. In a method of cladding a ferrous core with powdered cupreous metal, the steps comprising, in combination, moving said core substantially longitudinally through an applicator, feeding powdered cupreous metal to said applicator to put said cupreous metal or said core, passing said core and cladding through a compacting pass in a set of pressure rolls, roll pressing said cladding into intimate compaction against the surface of said core in said pass a density approaching that of solid metal, rapidly heating and rolling said pressed clad core at a temperature in the neighborhood of about 1900" F. but below the melting point of said cupreous metal to cause said cladding to become coherent and to adhere to said core with a metallurgical bond.

7. In a method for continuously cladding a metal core in rod or wire form with a cladding metal, initially in powder form, of lower melting point and lower strength which will form a coherent cladding and metallurgically bond with said core, the steps comprising, in combination, pulling said core continuously at a predetermined speed, feeding an annulus of said cladding metal in powdered form under a positive pressure in the direction of and into contact with said core, radially and simultaneously compacting the cladding metal powder against said core to a substantially uniform thickness around the periphery thereof at sufiicient pressure to densify said cladding metal to a value which approximates the density of the cladding metal in solid form, inductively heating the compacted clad core at least at the interface between said cladding and core metals to a temperature in the neighborhood of but below the melting point of said cladding, radially and simultaneously reducing the compacted heated clad core uniformly around the periphery thereof relatively soon after said heating at sufficient pressure to effect a reduction in the cross section both of the cladding and core metals, cause said cladding to become coherent and metallurgically bond said cladding and core metals together.

8. In a method for continuously cladding a metal core with a cladding metal, initially in powder form, of lower melting point and lower strength which will form a coherent cladding and a metallurgical bond with said core, the steps comprising, in combination, moving said core along a work line at a predetermined speed, feeding said powder metal in the same direction into engagement with said core to provide a layer of cladding thereon of predetermined thickness, immediately engaging said green clad core by rolls over the whole surface thereof to compact said cladding to a density approaching that of the cladding metal in solid form, rapidly heating at least the interface between the core and the compacted cladding to a temperature in the neighborhood of but below the melting point of the cladding metal, and engaging the compacted clad core while heated by further rolls exerting a rolling pressure sufficient to cause said cladding to become continuous and coherent and metallurgically bonded to said core to provide a bimetallic clad core product.

9. In a method of cladding an elongated ferrous member with aluminum, the steps comprising, in combination, cleaning the surface of said member to be clad to provide a somewhat roughened surface free of foreign matter, covering said surface with aluminum powder to a desired thickness, roll pressing said powder and member together uniformly over the whole surface to make the cladding particles relatively dense and adherent one to the other and form a green clad member, heating at least the interface between such cladding and member to a temperature in the range from about 900 F. to a temperature not in excess of 1200" F roll pressing said heated green clad member at sufficient pressure to effect a reduction in the cross section thereof up to a maximum of about 25% and recrystallization in the metallographic structure of said cladding, whereby non-porous aluminum cladding is obtained with metallurgical bonding thereof to said ferrous member at the interface.

10. In a method of cladding a metallurgically clean ferrous core in rod form with aluminous metal initially in the form of powder particles, the steps comprising, in combination, pulling said core and said aluminous metal cladding after application thereto along a straight line, passing said core through a larger orifice of predetermined size, feeding said particles substantially at atmospheric temperature under a positive pressure in an annulus in the direction of the movement of said core toward said orifice to engage said core to a substantially uniform thickness and pass therewith through said orifice, passing said particle clad core through a closed roll pass to compact said particles substantially :at atmospheric temperature against said core around the entire periphery thereof to a density around the periphery and along the length thereof approaching the density of said aluminous metal in solid form, rapidly heating said compacted clad rod to a temperature at the interface in the neighborhood of llO F., passing said compacted clad rod at said temperature through a closed roll pass which is smaller by an amount not less than about than the cross sectional area of said compacted clad rod entering said last-mentioned pass, said above-mentioned passes being defined by rolls driven at about the speed of said clad rod produced by said firstmentioned pulling, removing outstanding longitudinal fins from the surface of said clad rod adjacent the base of said fins respectively as said clad rod issues from each of the above-mentioned passes, passing said clad rod through a further closed pass, and relatively rapidly cooling at least said cladding on said clad rod.

11. In a method of cladding a metallurgically clean ferrous core in rod form with aluminous metal initially in the form of powder particles, the steps comprising, in combination, pulling said core and said aluminous metal cladding after application thereto along a straight line at a predetermined speed, passing said core through a larger orifice of predetermined size, feeding said particles under a positive pressure in an annulus in the direction of the movement of said core toward said orifice to engage said core to a substantially uniform thickness and pass therewith through said orifice, passing said particle clad core through a closed roll pass to compact said particles against said core around the entire periphery thereof to a density around the periphery and along the length thereof approaching that of solid metal, rapidly heating said compacted clad rod to a temperature at the interface in the neighborhood of 1000 F. to 1175 F., and passing said heated compacted clad rod through a closed roll pass which is smaller than the cross sectional area of said compacted clad rod entering said last-mentioned pass, said above-mentioned passes being defined by rolls at least some thereof being driven at about said speed.

12. In a continuous method of making an aluminum clad ferrous core rod, the steps comprising, in combination, multiplan-e straightening of said core in rod form, metallurgically cleaning the surface of said core by abrasion to provide an unsmooth texture free of foreign matter, concentrically feeding atomized aluminum powder around said core and engaging the same in the bite of power-driven rolls forming a closed grooved pass slightly smaller than the overall diameter of said entering pressed powder and core to compact and densify the green cladding on said rod, induction heating said compacted green clad rod to a temperature in the neighborhood of 1050* F. to 1150 F. for a period not in excess of ten seconds at a frequency to penetrate through said cladding and the interface between said cladding and core, promptly engaging said compacted and heated clad rod in the bite of further powerdriven rolls forming a closed modified shape pass, maintaining a lubricant film on contact surfaces of said rolls, said last-mentioned pass being sufficiently smaller in cross section to reduce the cross section of said clad rod in the neighborhood of from 15% to 20%, removing longitudinal fins respectively as said clad rod emerges from said respective power-driven roll passes, rolling said reduced clad rod to finish shape it, cooling said clad rod leaving said last-mentioned rolling step, and pulling said clad rod in a straight line extending to said straightening step.

13. A continuous method of cladding an elongated strength metal core with a cladding metal initially in powder form having a relatively lower tensile strength and melting point, comprising, in combination, moving the core longitudinally in a straight line through a cladding metal applying zone, feeding powder cladding metal in a positive manner against said core in said applying zone, roll pressing said cladding metal against said core into intimate compaction thereagainst to a density approaching that of said cladding metal in solid metal form, rapidly heating at least the interface between said compacted cladding metal and core to a temperature approaching the melting point of said cladding metal without causing the melting of said cladding metal, and substantially immediately rolling said heated clad core to provide a continuous coherent cladding metal layer and a metallurgical bond between said cladding metal layer and said core.

14. A continuous method of cladding as set forth in claim 13, in which, said core is ferrous metal, said cladding is aluminous metal, said heating is induction heating and said temperature is between about 1000 F. and about 1180 F. but below the melting point of said aluminous metal.

15. A continuous method of cladding as set forth in claim 13, in which, said core is ferrous metal, said cladding is cupreous metal, said heating is induction heating and said temperature is between about 1600" F. and about 1900 F. but below the melting point of said cupreous metal.

16. A bimetallic clad product comprising, in combination, a preformed ferrous or alloy core, a cladding comprising a continuous coherent layer of aluminous metal metallurgically bonded to said core, said cladding originally comprising powder metal compacted against said core to a density approaching that of solid metal and remaining substantially in unmeltcd condition throughout rapid heating at a temperature in the neighborhood of from about 1000 F. to about 1150 F. but below the melting point of said aluminous metal and rolling said heated clad core at sufficient pressure to cause said cladding to become coherent and adhere to said core with a metallurgical bond, the interface between said cladding and core being substantially free of any continuous or substantial layer of brittle aluminous metal-iron compound.

17. A bimetallic clad product comprising, in combination, a preformed ferrous or alloy core, a cladding com prising a continuous coherent layer of cupreous metal m-etallurgically bonded to said core, said cladding originally comprising powder metal compacted against said core to a density approaching that of solid metal and remaining substantially in unmelted condition throughout rapid heating at a temperature between about 1600 F. and a temperature in the neighborhood of about 1900 F. but below the melting point of said cupreous metal and rolling said heated clad core at sufiicient pressure to cause said clad to become coherent and adhere to said core with a metallurgical bond, the interface between said cladding and core being without extensive diffusion of said cladding UNITED STATES PATENTS Simons June 1, 1943 20 Patterson Nov. 2, Schwarzkopf Mar. 27, Wellman Oct. 12,

Lambert et a] Nov. 22, Findlay et al July 13,

Claims (1)

16. A BIMETALLIC CLAD PRODUCT COMPRISING, IN COMBINATION, A PREFORMED FERROUS OR ALLOY CORE, A CLADDING COMPRISING A CONTINUOUS COHERENT LAYER OF ALUMINOUS METAL METALLURGICALLY BONDED TO SAID CORE, SAID CLADDING ORIGINALLY COMPRISING POWDER METAL COMPACTED AGAINST SAID CORE TO A DENSITY APPROACHING THAT OF SOLID METAL AND REMAINING SUBSTANTIALLY IN UNMELTED CONDITION THROUGHTOUT RAPID HEATING AT A TEMPERATURE IN THE NEIGHBORHOOD OF FROM ABOUT 100*F. TO ABOUT 1150*F. BUT BELOW THE MELTING POINT OF SAID ALUMINOUS METAL AND ROLLING SAID HEATED CLAD CORE AT SUFFICIENT PRESSURE TO CAUSE SAID CLADDING TO BECOME COHERENT AD ADHERE TO SAID CORE WITH A METALLURGICAL BOND, THE INTERFACE BETWEEN SAID CLADDING AND CORE BEING SUBSTANTIALLY FREE OF ANY CONTINUOUS OR SUBSTANTIAL LAYER OF BRITTLE ALUMINUOUS METAL-IRON COMPOUND.

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