US3080649A - Continuous process of hot-forming metal - Google Patents

Description

March 12, 1963 E. F. ELLloTT 3,030,649

coN'rINUous PRocEss 'oF HOT-Femme METAL Filed June 1o. 1959 2 sneetspsneea 1 March 12, 1963 E. F, ELLIOTT 3,080,649

CONTINUOUS PRocEss oF HOT-FORMING METAL Filed June l0, 1959 v 2 Sheets-Sheet 2 25k/dif United States Patent Q 3,080,649 CNTINUUS PRGCESS F IdT-FRMING METAL Ernest F. Eiiiott, Rte. 1, Houghton Lake, Mich. Fiied .lune it?, 1959, Ser. No. 819,406 1 iairn. (Cl. 29-5290 This invention relates to processes and apparatus for metal working and, in particular for hot forming, such as for extrusion or forging.

Hitherto, in the hot forming of metals, such as steel, by extrusion or forging, the steel ingots have been separately cast, then heated in a so-called soaking pit to raise their temperatures to a level suicient to render their structure suitably homogenous for subsequent hot forming operations. Under such prior procedure, the heat contained in the ingot while it is being cast from the pouring of molten steel or other metal is largely or wholly lost, as is also the time expended in the cooling of the original ingot after casting and its subsequent reheating in the soaking pit. The coating of prior ingots with ceramic or other oxide-removing material has also required the use of large furnaces as well as the addition of considerable heating facilities in order to bring the ingot up to the necessary high temperature for such coating and subsequent hot-forming operations.

Accordingly, one object of this invention is to eliminate these prior disadvantages by providing a process of producing and homogenizing metallic ingots while removing their oxide coating by immersing them in molten oxide-absorbing coating material, such as ceramic materials, for example, glass or other silicate compounds, wherein the ingots are poured directly into molds from a receptacle containing molten metal, either with or without a container in the mold, allowed to cool suciently to solidify to permit handling, moved into or through a homogenizing furnace which also coats the ingots or the container-surrounded ingot with an oxideremoving coating, such as a ceramic coating for removing scale and minimizing oxidation, then passed through a scraper to remove excessive coating material and nally subjected to hot forming operations such as forging, rolling, pressing or extruding, thereby eliminating the previously required steps of reheating and handling of ingots made under conventional processes, homogenized in a soaking pit, and subsequently coated with oxide-removing material before carrying out the hot forming operations.

Another object is to provide a process of the foregoing character wherein the molten metal is poured into a container of suitable material, such as steel, or directly into a mold, in either case optionally containing a suitable lubricant which rises to the top of the molten metal, thus positioning the lubricant at the forward end of the ingot where it facilitates subsequent extrusion.

Another object is to provide a process of the foregoing character wherein the ingot is cast by pouring the molten metal into a container after which the container is capped and the container-surrounded ingot moved into a homogenized furnace where an oxide-removing coating is applied to the container, after which the container-surrounded ingot is subjected to hot forming operations, such as extrusion or forging.

Another object is to provide a process, as set forth in the preceding objects wherein much of the heat contained in the molten metal before pouring is conserved by handling the poured ingot immediately after casting, either alone or within a surrounding container, thereby reducing to a minimum the amount of additional heat required to be supplied to the ingot during homogenizing and hot forming, and thus consequently reducing the sizes of furnaces and heaters needed, and increasing the speed of fr* f IC@ operations by carrying the metal from its molten state to its hot formed state in the minimum time and with the minimum of interruptions.

Other objects and advantages of the invention will become apparent during the course of the following description of the accompanying drawings, wherein:

FIGURE 1 is a top plan view, partly in longitudinal section, of an apparatus suitable for carrying out the process of the present invention, according to one form of the invention, wherein the ingot is surrounded by a container;

FIGURE 2 is a vertical longitudinal section taken along the line 2-2 in FIGURE l;

FIGURE 3 is a vertical cross-section taken along the line 3-3 in FIGURE 1, showing the ingot-handling arrangement at the entrance to the coating furnace;

FIGURE 4 is a vertical cross-section taken along the line 4 4 in FIGURE 1, showing the ingot-handling arrangement at the discharge end of the furnace, together with means for scraping the oxide-removing coating material directly from the ingot or from the container-surrounded ingot, as the case may be;

FIGURE 5 is a vertical cross-section taken along the line S-5 in FIGURE 2, showing a container-surrounded ingot being coated with oxide-removing material in the rotating furnace;

FIGURE 6 is a diagrammatic vertical section through a modilication of the invention showing a ladle and split mold for the casting of an ingot without the use of an ingot container, but with pouring partially carried out directly into the mold, and with a layer of lubricant material in the mold; and

FIGURE 7 is a diagrammatic vertical section through a further modification of the invention showing one of the mold halves of a split mold similar to that of FIG- URES 2 and 6 provided with a heat-resisting liner shell formed in separable halves conforming to the mold halves and remaining with them when the mold halves are sep arated and the ingot ejected.

Referring to the drawings in detail, FIGURES 1 and 2 show an apparatus, generally designated 10, for casting, protectively coating and hot-forming metal ingots according to one form of the invention, wherein the ingot is surrounded by a container, as consisting generally of a tiltable ladle or other molten metal holder 12, a mold 14 within which is mounted a container 16 of steel or other snitabie heat-resisting material. The container 16 is Subsequently provided with a cap 18 in a capping machinel 2t) to form a composite ingot 22 consisting of a container 16 outside an ingot proper or ingot core 24. The apparatus 10 also includes an ingot feeder 26 which guides and moves the composite ingots 22 into a homogenizing furnace 28, from which the composite ingots 2.2 are discharged onto a troughshaped coated ingot receiver 29, and thence into a scraper or scraping machine 30 for the removal of the oxide-containing coating material. A hot-forming machine, generally designated 32, subjects the composite ingot 22 to extrusion, forging or other hot forming procedure.

The molten metal holder 12 is preferably a ladle shown in FIGURE 2 in its vertical position in solid lines and in its advanced til-ted position for pouring the vmetal M in dotted lines rIhe ladle 12 has a receptacle 34 mounted upon trunnions 36 which in turn are pivotally mounted in trunnion bearings 3S (FIGURE l). The latter can be advanced and retracted for moving the ladle 12 between its vertical solid line position and its tilted dotted line poufing position of FIGURE 2. The ladle 12 is provided with a pouring lip it? by which the molten metal M is deposited in the receptacle 16 `which in turn is mounted within the mold 14. The trunnion bearings 3Sv for the receptacle 34 of the ladle 12 are mounted, by means not shown, for motion back and forth along a platform 42 which in turn is mounted upon a base structure, generally designated 44.

The mold 14 which is made of high-temperature-resistant material, such as graphite and water-cooled, is also mounted upon the platform 42 and includes a pair of cooperating separable mold halves 46 and 48 which carry coaxial brackets 50 and 52 respectively mounted on a vertical pivot shaft 54 rising from the platform 42. The mold halves 46 and 48 may be swung around the pivot shaft 54 between their open and closed positions, as shown in the dotted and solid lines respectively in FIGURE. l, by means of fluid pressure cylinder units, generally designated 56. Each unit 56 includes a cylinder 58 pivotally mounted on a pivot shaft 60 supported in a bracket 62 projecting laterally from the platform 42. Reciprocably mounted in each cylinder 58 is a plunger or piston 64, the outer end of which is pvotally connected at 70 to a bracket 72 secured to the side of its particular mold half 46 or 48.

'I'he two mold halves 46 and 48 have semi-cylindrical matching mold cavities 74 and 76 respectively which in the closed positions of the mold halves 46 and 48 cooperatively form a cylindrical mold cavity 75 adapted to receive the correspondingly-shaped container 16. The latter is made from a suitable heat-resistant metal, such as alloy steel, and is cup-shaped containing a cavity 78 into which the metal M is poured, as described below in connection with the operation of the invention. As also described below, a portion F of a Isuitable conventional lubricant, such as glass, graphite, metallic oxides, sulphides or carbonates, for example molybdenum sulphide, is placed in the bottom of the container 12 before pouring.

The capping machine is conventional and its details are beyond 'the scope of the present invention. It is diagrammatically illustrated `in FIGURES 1 and 2 as consisting of a capping die 80 with a bore 82 adapted to receive and apply the cap 1S to the container 16 after the latter has been supplied with a quantity of lubricant F and filled with molten metal which has partially solidied into the ingot core 24, as described below. The capping die 80 is mounted on a platen 84 which in turn is adapted to be raised fand lowered by an outer tubular operating rod 86. Reciprocably mounted within the bore 82 and connected to an inner operating rod 88 is a capping head 90 which is thereby reciprocable relatively to the capping die 80. The operating rods 86 and 88 are connected to mechanical or hydraulic devices for reciprocating them either as a unit or relatively to one another in a manner familiar to those conversant with the capping art. The capping machine 20 is mounted on a. step 92 raised above the platform 42 and immediately adjacent the entrance to the ingot feeder 26. While the composite ingot 22 is being capped, its bottom rests upon the step 92.

Associa-ted with the capping machine is conventional ingot handling means, such as conventional swinging tongs (not shown) for transferring the capped composite ingot 22 from the vertical position on the step 92 to its horizontal position upon the ingot feeder 26. The latter includes a reciprocable feeding ram or pusher rod 93 aligned with a horizontal trough structure 94 resting upon the base structure 44 and directed toward the entrance opening 96 in the homogenizing furnace 28, which at its opposite end has an exit `opening 97 closed by an exit door 99. The lcapped composite ingots 22 are moved along the trough structure 94 through the furnace opening 96 by the pusher rod 93 either manually or by poweroperated means, such as a hydraulic motor or screw shaft (not shown) and are similarly ejected `through the exit opening 97 by being pushed by the following ingots 22 while the entrance and exit doors 9S and 99 are swung out of the way. This is accomplished by mounting eaCh door 98 or 99 on an arm 100 which is pivotally mounted on a pivot `shaft 102. Each arm 100 on its opposite end carries a counterweight 104- with a handle 105 (FIG- URES 1 and 3). The pivot shaft 102 is rotatably mounted in `spaced upstanding bearing brackets 106, the lower ends of which rest upon the base structure 44. The outer end of each pivot shaft 102 terminates in a crank arm 10S by which each pivot shaft 102 may be rotated so as to swing each door 98 or 99 into and out of closing relationship with its respective entrance or exit opening 916 or 97 of the homogenizing furnace 28.

The entrance door 98 swings downward and is notched or otherwise cut away as at (FIGURE 3) for the passage of a burner 112 supplied with fuel through a fuel pipe 114 connected to a source of fuel such as a combustible gas or oil. The burner 112 is adjusted by means of a hand wheel 116, and projects through the entrance opening 96 into the furnace chamber 118 formed in a furnace lining 120. The furnace chamber 118 has an elongated large-diameter bore 122 of cylindrical or frustoconical shape connected to the entrance opening 96 and exit opening 97 (FIGURE 2) by ared entrance and exit portions -124 and 126 respectively. This construction places the lowermost portion of the bore 122 below 'the level of the entrance and exit openings 96 and 97 vso as to permit the lower portion of the chamber 118 to receive a charge C of metallic oxide removing material, such as glasses or other suitable ceramic oxide-removing material, adapted to become a molten bath under the heat supplied by the burning gases emitted by the burner 112, and in which the ingots 22 are immersed either partly or completely, as desired. The furnace lining (FIGURES 1, 2 and 5) is made of refractory material adapted to withstand the high temperature, such refractory material being well-known to those skilled in the glass and steel industry and including various types of silica-alumina tire brick and tire clay.

The furnace lining 129 in turn is mounted in a rotary casing, generally designated 130, including `a horizontal cylindrical portion 132 (FIGURE 2), carrying axiallyspaced annular channel tracks 134 and having its ends closed by disc- shaped heads 136 and 138 containing en trance .and exit openings 140 and 142 respectively aligned with the entrance and exit openings 96 and 97 in lthe furnace lining 120. The annular channel tracks 134 rest upon the rollers `or wheels 144 and 146 which in turn are mounted on parallel shafts 143 and 150 respectively journaled at their opposite ends in bearing brackets 152 and 154. The shaft 148 carries and is driven by a pulley 156 through a belt or sprocket chain 158 from a pulley 160 on a countershaft 162 journaled in the bearing bracket 152 at one end and at its opposite end in a bearing bracket 164. Drivingly secured to the countershaft 162' is the pulley 166 driven by a belt 168 from a pulley mounted on the armature shaft 172 of an electric motor 174. In this manner, the motor -174 rotates the furnace 28 at a greatly reduced speed so as to roll the ingots 22 around in the bore 122 while they are partly or completely immersed in the bath of molten ceramic material C, such as molten metallic-oxide-removing glass, which removes the surface scale or other oxides from the ingots or from the containers surrounding the ingots, as the case may be.

The thus-coated and homogenized ingots are pushed or pulled through the exit or discharge opening 97 of the furnace 28 and drop one by one onto the coated ingot receiver 29 (FIGURES l, 2 and 4). The receiver 29 includes a stationary inclined elongated rest 176 (FIG- URE 4) and an oppositeIy-inclined movable rest 178 pivoted thereto on a pivot shaft 180, The stationary rest 176 is mounted on stanchions 182 secured to and rising from the base structure 44. A crank handle 184 mounted on the end of the pivot shaft (FGURE 2) enables the movable rest 178 to be tilted from an upwardly-inclined position to a Adownward]y-inclined position in order to release an ingot 22 being temporarily held by the coated-ingot receiver 29.

From the coated ingot receiver 29, an inclined upper chute 186 leads downward to the scraper 30` from which an inclined lower chute 188 leads further downward to a horizontal coated ingot receiver or rest 190 mounted on stanchions 192 (FIGURE 4). The scraper 30 for removing the excessive glass or ceramic materials from the ingots includes a tilting ingot holder 194 of V-shaped crosssection (FIGURE 4) mounted on a pivot shaft 196 by which it is adapted to be swung selectively toward the upper chute 186 to receive an unscraped ingot or toward the lower chute 188 to discharge a scraped ingot. Each coated ingot 22 to be scraped is deposited between rotary serrated or toothed end-scraping heads 198 and 200 which scrape its opposite ends. The heads 193 and 200 are spaced apart from one another and mounted on a rotatable shaft 202 carrying a pulley or sprocket 204 driven by a belt or sprocket chain 206 from a pulley or sprocket S drivingly secured to the shaft 148. Rotary scraper d knives 210 mounted on and swingable with the ingot holder 194 near the upper edges of its opposite sides scrape the glass or ceramic materials oif the sides of the container 16 of the composite ingot 22 after the glass coating has removed the oxide scale from the external surface of the container 16 or ingot, as the case may be.

The scraper 30 is also conventional and its details are beyond the scope of the present invention. It may be replaced by any other conventional scraper, such as the well-known axial scraper with peripherally-spaced knives past which the billet is pushed axially lby a plunger, as is familiar to those skilled in the ingot coating art.

The hot forming machine 32, shown diagrammatically in FIGURE 1, is also conventional and, as shown, comprises an extrusion machine having spaced stationary heads 212 and 214 interconnected by strain rods 216 with an ingot-receiving space 218 between them into which the scraped ingot 22 is deposited. There it is subjected to the action of a reciprocable plunger or ram 220` which forces the ingot through the extrusion die in the head 212, as is likewise `familiar to those skilled in the metal extrusion art. The hot forming machine 32 is also shown diagrammatically, as its details are beyond the scope of the present invention and may be obviously replaced by a forging press or other means for further working the ingot 22 at high temperature.

The modified arrangement shown in FIGURE 6 consists of a `split mold 14 identical in construction with the mold 14 showniin FIGURES l and 2 except that no receptacle whatever is used, the metal L being poured directly into the mold cavity 75 rather than into a receptacle, as described below in connection with the operation of this modification.

rlhe modified arrangement shown in FIGURE 7 consists of a split mold. 14 also identical in construction with the mold 14 shown in FIGURES l and 2, except that it contains a. pair of hollow semi-cylindrical alloy steel shells 222 which in assembly form a mold lining but which remain with the mold halves 46 and 48 and do not adhere to and remain with the ingot 224. The latter, when dis charged lby the swinging apart of the mold halves 46 and 43 and the shells 222, lacks any receptacle 16 and is picked up by conventional ingot-handling tongs (not shown) and is pushed into the furnace 28 along the ingot feeder 26 by the pusher rod 93 (FIGURES 1 and 2). The ingots 224 are thus directly coated with molten glass or other molten oxidcremoving material C which has the property of taking off the scale or oxide layers formed on the outside of the ingots. The remainder of the ingottreating operations are identical with those followed in connection with the composite ingot 22 of FIGURES l to 5 inclusive.

While the process of FIGURES l to 5 inclusive has been described and illustrated as mounting the container 16 in the mold 14, it will be understood that by using a container 16 of sufficient self-sustaining rigidity under the high temperature of the molten metal, the latter may be poured directly into the container 16 in the absence of a mold 14, allowed to at least partially solidify, and then handled subsequently in the manner described below, thereby eliminating the use of the mold 14.

In the operation of the apparatus 10, and in carrying out the process of the present invention, molten steel or other molten metal to be cast into ingots is deposited in the receptacle 34 of the molten metal ladle or other holder 12. An empty container 16 is then placed -between the mold halves 46 and 4S which are then moved into their closed position shown in the solid lines in FIGURE l. The ladle 12 or other molten metal holder is then moved forward and tilted into the dotted line position of FIGURE 2, to pour the molten metal from the pouring lip 40 into the cavity 78 in the container 16, which has been previously charged with a level of lubricant F, as mentioned above. As the level of the molten metal rises in the receptacle 75, the lubricant F floats to the surface as a slag, purifying the molten metal by absorbing impurities and oxides. The layer of lubricant F is allowed to remain at the top of the container 16, where it subsequently serves as a lubricant to lubricate the forward end of the ingot 22 or 224 during extrusion of the ingot, as explained below.

The metal in the container is allowed to cool sufficiently for it to solidify at least partially, say from 2600 F. down to 2300 F., by chilling brought about through water-cooling the mold halves 46 and 48. The fluid pressure cylinder units 56 are then operated to move the mold halves 46 and 48 into their open dotted line positions (FIGURE l) whereupon the thus-formed composite ingot 22 consisting of the receptacle 16 and hot steel or other metal core 24- is grasped by conventional tongs (not shown) and moved into the capping machine 20. I-Iere the cover or cap 18 is pressed .down upon the upper end of the receptacle 16, imprisoning the layer of lubricant F inside, immediately beneath the cover or cap 18 at the top of the ingot core 24, where it acts as a lubricant for the ingot core 24 in subsequent hot-forming operations. The capping die 89 and capping head El) are then moved upward by means of their respective Operating rods 86 and 8S and the capped composite ingot 22 grasped by the tongs (not shown) and swung from a vertical to a horizontal position while it is being deposited on the trough structure 94 of the feeder 26 (FIGURE 2). The feeding ram or pusher rod 93 is then moved to the left so as to push the extremely hot capped composite ingot 22 through the entrance opening 96 into the bore 122 of the furnace 23 while the entrance door 98 is temporarily lowered to permit this. Meanwhile, the burning gases from the burner 112 have melted the glass or other oxide-removing coating material C, such as glass, converting it into a pool of molten material in the bottom of the bore 122 into which the composite ingot 22 falls and is partly or wholly immersed, as desired.

While this has been going on, another receptacle 16 has been placed in the mold cavity '75, another charge of lubricant F deposited in its cavity 78 and another lling of molten metal M, such as steel, poured into the cavity '78. The uncapped metal with the lubricant F at the top is then allowed to rsolidify as before, whereupon it is transferred to the capping machine 2h, capped with a cover 18 and swung downward into a horizontal position on the trough structure 94 The feeder rod or ram 93 is again operated to push the composite ingot 22 for- Ward along the trough structure 94 into the furnace bore 122 immediately ybehind the previously deposited ingot 22. These operations are repeated until the furnace 28 has received its allotted number of ingots 22.

The furnace 28 is then rotated by the motor 174, causing .the composite ingots 22 to rotate as they roll relatively to the furnace lining 121) and receive a coating of glass or other molten oxide-removing material, which removes the oxide layer or scale that has been formed on the ingots 22. Meanwhile, other composite ingots 22 have been cast in containers 16 in the foregoing manner, capped and deposited upon the feeding, trough structure 94, ready to be pushed into the furnace 28 by the feeding rod 93.

When the foremost composite ingot 22 has been suiciently coated with glass to remove the oxides formed on the surface of the container 16, and also thereby suiiciently heated to render its internal structure homogeneous, the pusher or `feeder rod 93 is again operated to cause the foremost ingot 22 on the trough structure 94 to enter the furnace entrance opening 96. There it pushes against the rearmost ingot 22 in the furnace chamber 118, thereby causing the motion to be transmitted through the successive ingots 22 to the foremost ingot 22. The latter, when thus homogenized, is thus pushed up the inclined surface 126 and outward through the exit opening 97 while the exit door 99 is raised, assisted, if desired, by the use of a conventional pulling hook (not shown) inserted through the open exit opening 97. The ejected glass-coated composite ingot 22 is in this manner deposited on the ingot receiver 29 where it awaits its turn at the scraping machine 30.

When the scraping machine 30 is vacant, the crank handle 184 is operated (FIGURE 2) to rotate the shaft 180 counterclockwise (FIGURE 4) and release the coated ingot 22 to roll down the upper chute 186. Meanwhile, the ingot holder 194 has been rotated clockwise so as to intercept the descending ingot 22 at the lower end of the upper chute 186. The ingot holder 194 is then turned upward and the serrated end scraping heads 198 and 200 (FIGURE l) rotated to remove the oxide-impregnated glass or other coating material layer from the opposite ends of the ingot 22 while the rotary knives 210 remove the oxide-impregnated coating from the side surface of the container 16 of the ingot 22. The shaft 196 is then rotated counterclockwise to tilt the ingot holder 194 counterclockwise in order to dump the scraped ingot 22 onto the lower chute 138 whence it rolls onto the ingot receiver or rest 190.

The foregoing operations are conducted successively upon the successive composite ingots 22, whereupon the ingots 22 while still hot, are placed in the space in the extruding machine or other hot forming machine 32, and extruded. forged, rolled, pressed or otherwise hot formed. In eXtrnding the composite ingot 22, the receptacle 16 remains behind while the ingot core 24 is pushed through the extruding die, preceded by the layer of lubricant F which lies immediately behind the cover or cap 18. This layer of lubricant F lubricates the ingot core 24 and die and facilitates the passage of the ingots through the die.

The operation of the modified arrangements shown in FIGURES 6 and 7 is identical with that described above for the composite ingots 22, with the exception of the fact that the plain billets 224 are directly coated with molten oxide-removing material C such as glass and the scale or other oxides removed in that manner, scraped from the ingot in the scraping machine 30, and hot-formed such as by conventional extrusion, forging, rolling or pressing operations carried out in conventional hot-forming apparatus, as described above.

What I claim is:

A substantially continuous process of substantially uninterruptedly casting, deoxidizing, homogenizing and hotforming metal ingots directly from molten metal into products of predetermined shape, said process comprismg (A) depositing molten ingot metal in an elongated ingot mold cavity,

(B) cooling the molten metal in the mold into an at least partly solidied elongated hot ingot having a predetermined temperature higher than the customary homogenizing temperature for such an ingot,

(C) heating an elongated bath of oxide-removing matcrial to a molten state at a temperature at least as high as a satisfactory homogenization temperature for such an ingot and maintaining said bath at said temperature,

(D) moving the elongated hot ingot from the mold while still substantially at said predetermined homogenization temperature through said bath for a time period sufficient to effect homogenization thereof while simultaneously rolling the hot ingot within said bath and thereby causing the oxide-removing material to coat the hot ingot and absorb the oxide layer therefrom,

(E) withdrawing the thus-coated hot ingot from said bath while the ingot is still at substantially the homogenizing temperature,

(F) substantially immediately after such withdrawal removing from the hot ingot a portion of the now oxide-contaminated oxide-absorbing coating while the ingot is still at approximately the homogenizing temperature,

(G) and substantially immediately after such coating removal while the ingot remains at a temperature sufficiently high for hot-forming, subjecting the hot irlilgot to hot-forming into a product of predetermined s ape.

References Cited in the le of this patent UNITED STATES PATENTS 94,471 Burt Sept. 7, 1869 929,688 Monnot Aug. 3, 1909 1,983,760 Ingersoll Dec. ll, 1934 2,337,751 Ingersoll Dec. 28, 1943 2,832,700 Balestra Apr. 29, 1958 2,889,238 Long et al June 2, 1959 2,935,772 Shaw May 10, 1960 OTHER REFERENCES Making, Shaping and Treating of Steel, page 5, 7th edition, 1957.

The Making, Shaping and Treating of Steel, U.S. Steel, 7th edition, pp. 354 and 391.

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