US3089209A - Method for continuous casting of metal - Google Patents

Method for continuous casting of metal Download PDF

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Publication number
US3089209A
US3089209A US894A US89460A US3089209A US 3089209 A US3089209 A US 3089209A US 894 A US894 A US 894A US 89460 A US89460 A US 89460A US 3089209 A US3089209 A US 3089209A
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Prior art keywords
mold
casting
metal
gas
rate
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US894A
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Albert J Phillips
Baier Richard
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American Smelting and Refining Co
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American Smelting and Refining Co
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Priority to US894A priority Critical patent/US3089209A/en
Priority to DE19601433021 priority patent/DE1433021A1/de
Priority to GB485/61A priority patent/GB968866A/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/04—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds
    • B22D11/049—Continuous casting of metals, i.e. casting in indefinite lengths into open-ended moulds for direct chill casting, e.g. electromagnetic casting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/14—Plants for continuous casting
    • B22D11/141—Plants for continuous casting for vertical casting

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  • This invention relates to a process for continuously casting metal. More particularly, it relates to a process for continuously casting a copper metal, especially low oxygen copper.
  • the invention comprehends, in a method for continuously casting metal in which molten metal is introduced into one end of an open ended mold and cast metal is withdrawn from the other end of the mold, the improvement which comprises introducing a gas containing more than about 40% by volume of hydrogen to that area of the mold wall at which freezing of the introduced molten metal commences during the casting procedure.
  • a gas containing more than about 40% by volume of hydrogen to that area of the mold wall at which freezing of the introduced molten metal commences during the casting procedure.
  • such hydrogen gas is continuouslv introduced to said area of the mold.
  • the invention is especially useful in continuous casting procedures in which the molten metal is introduced into the chilled zone of an open ended, vertically disposed mold and the rate of introduction of the molten metal with respect to the rate of withdrawal of the cast metal is such as to maintain a free mold wall surface in the chill zone of the mold, i.e. a portion of the chill zone mold wall extends above the level of the metal in the mold.
  • the molten metal commences to freeze at the meniscus of the metal in the mold; and in accordance with the invention, the hydrogen gas is introduced to that area of the mold wall in which the meniscus of the molten metal is located.
  • such introduction of such hydrogen gas may be accomplished in any appropriate manner.
  • the gas may be introduced to said area by delivering it as such thereto from an outside source or by releasing such gas at said area in any other suitable manner from any suitable source.
  • introduction of the hydrogen gas is accomplished by conducting the hydrogen gas as such from an outside source to the mold adjacent the mold wall area where the incoming molten metal contacts the chilled wall of the mold.
  • the hydrogen gas may be introduced into the mold cavity above the level of the metal in the mold from a perforated ring disposed over the 3,089,209 Patented May 14, 1963 mold cavity above the metal in the mold or from ports in the mold wall above and adjacent to the metal level intended to be maintained in the mold during the casting procedure; or by diffusion throught the mold wall where the latter is fabricated of a sufiiciently porous material such as, for example, graphite.
  • Most efficient use of the hydrogen is made when it is introduced by diffusion through the mold wall.
  • the instant hydrogen gas is introduced to said mold wall area in controlled amounts.
  • control is effected most readily and advantageously by regulating the amount of introduced gas to obtain a surface of a desired character on the casting as is indicated on the latter as it emerges from the mold.
  • the appearance of an irregular pattern of irregularities on the surface of the emerging casting is indicative that introduction of the hydrogen gas is approaching undesirably excessive amounts and an irregular pattern of irregularities on a major portion of the surface of the emerging casting indicates an undesirable excess of the introduced gas.
  • An irregular pattern of irregularities saving the appearance of cold shuts or folds which are perceptible to the touch are typical of such an irregular pattern on the surface of the casting.
  • a further feature of the invention comprises controlling the introduction of the hydrogen gas to said mold wall area to a rate which is below that at which an irregular pattern of irregularities occurs on a major portion of the surface of the emerging casting and above that at which deep tears occur in the casting emerging from the mold.
  • the invention is most advantageously used in casting procedures employing a vertical mold in which the level of the molten metal in the mold is maintained below the top of the chilled zone of the mold and the level of the meniscus of the molten metal in the chill zone is moved in vertical reciprocal relative movement with respect to the mold wall during the casting procedure.
  • Such reciprocal movement of the meniscus may be obtained by any appropriate relative movement between the mold wall and the metal therein; for example, by horizontal reciprocation of the sides of a segmented mold or, more preferably, by vertical reciprocation of the mold.
  • the introduction of the instant gas to the mold wall area upon which the meniscus moves is regulated to obtain regular, uniformly spaced ripples on the surface of the emerging casting.
  • a hydrogen gas containing any amount of hydrogen may be employed in practicing the invention provided the gas contains more than about seas by volume of hydrogen. Preferably. the gas contains at least by volume of hydrogen and most preferably is a substantially pure hydrogen gas such as is available commercially.
  • the concentration of the hydrogen in the instant ga affects the amount of gas employed. In general, to obtain the same results when the concentration of the hydrogen in the gas is decreased, the amount of gas employed is increased and vice versa.
  • the amount of gas employed is also alfected by the manner in which the gas is introduced to the mold Wall area.
  • the casting speed is affected by the cross-sectional shape and size of the casting to be produced, the presence or absence of tapers in the chill zone of the mold, and the rate of reciprocation of the metal meniscus or freezing metal in the chill zones as well as by the heat conductivity of the metal being cast and the overall heat extractive capacity of the mold.
  • the reciprocation rate is increased as the casting speed (Le. the net rate of withdrawal of the casting from the mold) is increased and vice versa.
  • the presence of a converging taper on the mold wall defining the mold cavity increases the heat extractive capacity of the mold and permits the use of higher casting speeds than would otherwise be possible.
  • the casting speed is decreased as the least cross-sectional linear dimension of the casting is increased.
  • the invention may be practiced in any continuous metal casting procedure employing any conventional continuous casting mold fabricated of any conventional material. However, it is most useful in casting low oxygen copper in a mold in which the metal is cast against a graphite surface, especially a tapered graphite surface, by a procedure in which a free mold wall surface is maintained in the chill zone of the mold, especially when employing a cover of a particulate solid material on the surface of the metal in the mold during the casting procedure, and particularly when the meniscus of the metal in the mold during such procedure is moved in a reciprocal movement with respect to the mold wall during the casting of the metal in the mold.
  • Low oxygen copper as used in the specification and claims means a copper containing less than 0.015% oxygen, and includes oxygen free copper and copper which has been deoxidized with a suitable deoxidizing agent such as, for example, calcium, lithium, boron or phosphorous.
  • the introduction of the gas is controlled to a rate below that at which said irregular pattern begins to occur and above that at which deep tears, more preferably above that rate at which small visible surface tears, occur on the surface of the emerging casting, and still more preferably above that rate at which small visible surface scuffs occur thereon and most preferably above that rate at which the surface of the casting is glassy smooth.
  • the introduction of the gas is regulated to obtain regular uniformly spaced ripples on the emerging surface of the casting.
  • the gas is introduced at a rate sufiicient to maintain the regular uniformly spaced ripples on the emerging casting surface during the entire casting procedure.
  • the least linear dimension i.e. the thickness
  • Comparable speeds are obtained with other shapes and sizes and with other metal casting procedures taking into consideration size, shape and heat conductivity.
  • the least cross-sectiona1 linear dimension of the shape of the casting is about 2 to about 5 inches.
  • the reason or reasons for the success of the present process are not understood. Normally, in continuously casting metals, particularly copper, the presence or use of hydrogen is avoided at all costs because of its known detrimental effect on the physical properties of the metal. In the instant process, however, the hydrogen has the beneficial effects described herein. Moreover, so far as we are aware, the hydrogen has no detectable affect on the composition of the metal being cast. Thus, for example, in casting copper containing up to .015 oxygen, there was no perceptible reduction in the oxygen content of the cast copper. While we do not wish to be bound by any particular theory, it is possible that the hydrogen may affect surface tension at the involved mold wall area so as to result in the benefits obtained in practicing the invention.
  • FIG. 1 is a diagrammatic view in side elevation and partly in section of a casting system employing the preferred mode of introducing the instant hydrogen gas to the mold;
  • FIG. 2 is a diagrammatic elevation in section of the mold illustrated in FIG. 1;
  • FIG. 3 is a half plan section taken on line 33 of FIG. 2, half of the mold being omitted for simplicity of illustration;
  • FIG. 4 is a diagrammatic view of a portion of the mold and siphon shown in FIG. l and illustrates freezing of the metal in the mold;
  • FIG. 5 is a view taken on line 5-5 of FIG. 2;
  • FIG. 6 is a diagrammatic elevation in section illustrating an alternative mode of introducing the instant hydrogen gas to the mold
  • FIG. 7 is a view from the bottom of the ring shown in FIG. 6;
  • FIG. 8 is a diagrammatic elevation in section illustrating another alternative mode of introducing the instant gas to the mold
  • FIG. 9 is a view taken on line 9-9 of FIG. 8;
  • FIG. 10 is a drawing illustrating the surface on a casting produced in accordance with the best mode of practicing the invention.
  • FIG. 11 is an enlarged view in side elevation in section further illustrating the surface shown in FIG. 10.
  • FIG. 1 illustrates a casting system which is at present preferred for the continuous casting of low oxygen copper.
  • a melting furnace (not shown) supplies holding furnace 10 with the molten metal to be cast.
  • Furnace 10 supplied pouring ladle 11 which in turn supplies siphon 12.
  • the latter supplies mold 13 which is mounted on platform 14 which in turn is mounted for vertical reciprocation on carriage 15.
  • the casting 17 is Withdrawn from the mold by a conventional roll drive mechanism 18 and is cut into desired lengths by a conventional cut-off mechanism, such as is illustrated by cut-oil saw 19.
  • a conventional cut-off mechanism such as is illustrated by cut-oil saw 19.
  • Such conventional mechanism is disclosed in Beterton and TruS. Patent No. 2,291,204, granted July 28, 1942.
  • the casting 17 Before passing to roll drive mechanism 18, the casting 17 may be passed through chamber 20 which may be provided with a suitable sealing gasket 21.
  • the carriage may be movable horizontally on tracks 16 from over tank to permit installation of molds of different size or shape or otherwise provide access to the mold.
  • a stationary working platform (not shown) may be located on opposite sides of track 16 and at the same level on which workmen may walk during the casting procedure.
  • the holding furnace 10 shown may be an upright low frequency induction furnace rotatable about a horizontal axis and having a pouring spout 25. It may receive molten metal through a launder or a bull ladle (not shown) from a suitable melting furnace.
  • the construction and operation or the pouring ladle 11 and siphon 12 illustrated in FIG. 1 are disclosed in copending application, Serial No. 724,114, filed March 26, 1958 by Richard Baler and entitled, Continuous Casting.
  • Such a ladle and siphon are preferred as the pouring mechanism for high speed casting, especially high speed casting of shapes in which the least cross-sectional linear dimension is less than about 5 inches although, if desired, other pouring mechanism may be used, especially for slow casting speeds or larger shapes.
  • mold 13 illustrated in FIGS. 2 and 3 are also disclosed in said copending application in that the preferred mold 13 is provided with at least two cooling zones, in the first of which the metal being cast is cooled solely by contact with the cooled mold walls, then by contact both with the cooled mold wall and with water or other fluid coolant in a second zone, and preferably also solely by direct contact with the coolant in a third zone.
  • the mold wall defining the mold cavity preferably is tapered to converge toward the end of the mold from which the casting emerges and the second cooling zone is provided with nozzles for discharging the coolant against the emerging casting at such an angle with respect thereto as to provide a venturi action as disclosed in said copending application.
  • the pouring ladle 11 may comprise an enlarged bowl 26 constituting a reservoir for the molten metal, and a trough 27 which supports the siphon 12.
  • the ladle also has a skim gate 28.
  • the ladle 11 is supported by a mechanism which permits tilting the ladle to change the elevation of the reservoir with respect to the siphon; raising and lowering the entire ladle without tilting it; and swiveling the entire ladle from a position (shown in FIGS. 1 and 4) with the siphon 12 over the mold 13 to a position over a slag pot (not shown) alongside the mold.
  • an elevator cylinder 31 whose lower end is fixed; cylinder 31 having a piston connected to pedestal carriage 32. Operation of elevator cylinder 31 raises and lowers the entire pedestal carriage 32 as a unit.
  • the pedestal 32 cariers an arcuate guide track device 33 on which is movably mounted a ladle carriage 34. Arcuate track 33 is laid out on the arc of a circle whose center is the center of siphon cup 42.
  • the ladle carriage 34 carries rollers 35 which ride on the arcuate guide 33.
  • a tilting cylinder 36 connects with a cross member 37 secured to the pedestal 32; and its piston connects with the ladle carriage 34.
  • the pedestal carriage 32 is rotatable about the vertical axis of elevator cylinder 31 to permit the operator to swing the ladle 11 in a horizontal plane.
  • Operation of elevator cylinder 31 raises and lowers the ladle 11 without tilting it.
  • Operation of tilting cylinder 36 causes ladle carriage 34 to ride on arcuate track guide 33 and thus to tilt the ladle 11 in a vertical plane about the center of siphon cup 42; this tilting may be accomplished in any position of the ladle 11 in its arc of swing around the vertical axis of elevator cylinder 31, and in any elevation of pedestal carriage 32.
  • any operation of the tilting cylinder 36 to tilt the ladle 11 in either direction operates to change the level of the metal in the ladle and, with the pedestal carriage 32 at its lowermost position, does not change the elevation of the cup 42 from its proper position in the mold.
  • metal level in the ladle 11 may be changed either by tilting the ladle, or by adding metal to the ladle or by removing metal from the ladle.
  • the control of metal level in the ladle is used to control rate of metal flow through the siphon 12.
  • the ladle may be tilted back- Ward (i.e. carriage 34 lowered) far enough to stop flow through the siphon.
  • cup 42 is provided with overflow means. As shown in FIG. 4, cup 42 has a lower discharge opening provided with a steatite washer or nipple 53'.
  • the lower end of the siphon tube 40 has three circumferentially evenly distributed notches 54 and three corresponding lugs 55, to which the overflow cup 42 is welded, forming three cuplike overflow openings 56.
  • the siphon to discharge molten metal through both the lower steatite opening 53 and the three cup-like overflow openings 56.
  • Siphon tube 40 of siphon 12 is preferably made of stainless steel with an intermediate arched portion as shown.
  • the siphon tube 40 may be provided with shroud 43 (see P16. 4).
  • the shroud is U-shaped in cross section for the greater part of its length and follows the arched portion of the siphon tube.
  • the shroud is suitably attached to the siphon tube in spaced relationship thereto and is fitted into the ladle wall lining 46 where the siphon passes through the wall, to prevent loss of liquid metal when pouring molten metal through the siphon.
  • the shroud is provided with dam 47 which closes the shroud cross-section.
  • the forward end of shroud 43 has an upright front wall 49 which emerges from tubular extension 50.
  • the front wall 49 and the tubular extension 50 may have a series of holes 51 and the lower end of the tubular extension may be squeezed around siphon tube 40 to provide a restricted passage 52 or a series of such restricted passages, to assist in melting out a frozen siphon.
  • mold 13 is supported by a frame 14 which is vertically oscillated by a reciprocating mechanism.
  • a suitable prime mover (omitted for simplicity) is mounted on carriage 15, which reciprocates connecting rod 61.
  • Rod 61 is pivoted to a series of hell crank levers 62 on one side of the frame 14.
  • a series of bell crank levers 63 are pivoted to the carriage on the other side of frame 14.
  • Links 64 and 65 pivotally connect bell crank levers 62 and 63 to oscillatory frame 14.
  • a connecting rod 66 connects bell crank levers 62 and 63.
  • a series of guide posts 67 are supported on carriage 15, and slidably engage guides on frame 14 to insure vertical reciprocation of the mold in a substantially vertical straight line.
  • Any suitable means may be provided to vary stroke and frequency of vertical reciprocation of the mold.
  • the drive motor may have a crank arm whose length is adjustable. To vary frequency, motor speed may be changed.
  • Sleeve 94 may be made of any suitable commercial graphite and is machined to the desired shape.
  • the interior mold surface 80 is machined to provide a taper which converges toward the bottom of the sleeve although the surface 80 may, if desired, be a true cylinder.
  • the sleeve 94 is carefully fitted into block 79; the contacting surfaces being cylindrical and carefully machined so that solid-to solid contact is obtained between sleeve and block without any fluid layer at the interface which will interfere with excellent heat transfer.
  • sleeve 94 is made oversize with respect to the block 79 and is assembled into the latter by forcing it axially into the block.
  • the compression fit between the assembled sleeve and block is sufficiently severe to provide the solid-to'solid, fluid-free contact at operating temperatures.
  • the sleeve 94 may be omitted and the block 79 made unitary with the molding surface 80 machined directly into the block; such a unitary structure being preferred in molds for casting shapes such as cakes which in transverse cross section are square or rectangular or for other multi-sided shapes.
  • the manifold 70 delivers Water to the main cooling tubes 83 disposed in passages 96 which are bored into block 79 and to five levels of water sprays.
  • the manifold has a series of top holes 84; a series of bottom holes 85; its ledge 81 has a series of drilled passages 86; the ledge contains holes 78 to clear the main cooling tubes 83.
  • block 79 For water delivery to the top or first level sprays, block 79 is provided with a series of horizontal radial passages containing cross tubes 88, each of the latter having a nozzle tip 89 having a downwardly directed discharge passage disposed at an angle which is less than about 30 to the vertical and preferably is about 20 thereto.
  • the passages 88 connect with elbows 90 which are connected to fittings 91 connected to the top holes 84 in the manifold 70.
  • the inner face of the lower portion of sleeve 94 has clearance bays below the discharge nozzles 89 providing, in effect, vertical ribs or projections 92 which are available to support the casting while the water sprays are directed between the ribs onto the surface of the casting before it leaves the mold. With high casting speeds, this insures cooling the surface of the casting below the plastic range while so supported.
  • Such vertical grooves may also be V-shaped and are suitably spaced from each other preferably also by a distance of about /2 inch.
  • T he instant hydrogen gas from an outside source is conducted through pipe preferably to the uppermost horizontal ring 110 through at least one passage 121 machined in block 79, and preferably through at least three such passages distributed equi-distantly arouid the periphery of block 79.
  • the gas thus supplied to the uppermost groove flows around this groove to the remaining grooves from whence it is distributed by diffusing through the pores of the graphite to the inner surface area of the liner whici is embraced by the grooves; such diffusion taking place even under slight pressurefor example, as little as V2 pound per square inch, gauge, or less.
  • a sufficient number of the horizontal grooves are employed to insure the bracketing with such grooves of that area of the mold wall at which the introduced metal commences to freeze during the process.
  • the entire length of sleeve 94 is chilled and, as illustrated in FIG. 4, the introduced molten metal commences to freeze at the meniscus.
  • a suflicient number of horizontal grooves preferably at least five, are employed to accommodate reciprocation of the meniscus and also to permit change of the mean operating level of the metal in the mold.
  • FIGS. 6 through 9 Alternative modes of introducing the instant hydrogen gas are illustrated in FIGS. 6 through 9.
  • the gas may be introduced to the mold Wall area at which freezing of the introduced metal commences by conducting it from a source (not shown) to ring 125 from which it is discharged into the mold cavity above the metal therein through a series of downwardly directed perforations 126 of suitable size, for example, about 0.1 inch in diameter, spaced at regular intervals around the ring, preferably about /2 inch apart.
  • the gas may be introduced as illustrated in FIGS.
  • a conventional starting bar of appropriate length and having a cross section of a size and shape conforming to that of the mold cavity defined by mold surface 80 and preferably also having a conventional threaded tip of reduced size on the top thereof is employed.
  • the top of the starting bar is inserted into the bottom of the mold a sufiicient distance to cover the ribs 92 on sleeve 94 with the lower end of the bar extending below with drawal rolls 18 so that. as the initial molten metal is fed into the mold, it freezes around the threaded tip and the frozen product is pulled downwardly and out of the mold by rolls 18.
  • the siphon 12 is primed.
  • priming the siphon it is first heated at least to a dull red heat, and preferably to the melting point of the metal being cast, with a torch.
  • Ladle 11 hearing the thus heated siphon is then swiveled into a position over a slag pot and the ladle, which in the meantime has been filled with molten metal from holding furnace 16, is tilted forward sulficiently to bring the molten metal level in the ladle higher than the highest part of the arched portion of siphon tube 4% ⁇ with the dam 47 serving to retain the molten metal, thereby causing copious flow of molten metal through siphon tube 40 and through lower orifice 53 and upper orifices 56 in nozzle 42.
  • the size of orifice 53 in nozzle 42 is governed by the flow rate desired for the particular mold.
  • the relationship between the effective areas of orifice 53 and of the cross section of the siphon tube 46 is such as to build up sufficient head in the cup 42 to keep the level of molten metal in cup 42 above the end of the siphon tube during priming.
  • the combined effective area of the overflow orifices 56 and bottom orifice 53 should be greater than the effective cross sectional area of the siphon tube 40, so that maximum flow and velocity are obtained in the tube 40 in order to flush out gases. If orifice 53 is too small, the velocity through the siphon tube will be too low, allowing gas separation at the top of the arch of the siphon tube and loss of siphoning action or possible freezing of the metal in the siphon tube.
  • effective area is meant the area which controls the rate of flow through the several parts of the siphon, namely, the siphon tube 40, discharge orifice 53 and overflow orifices 56.
  • the size of orifice 53 was not greater than of the effective area of the siphon tube 40.
  • the best operating ratio was found to be between 30% and 60%.
  • the effective area of the overflow orifices 56 was not less than 50% of the effective siphon tube area.
  • the sum of the effective areas of orifice 53 and of the overflow orifices 56 should be nearly equal to (not less than 80%), or preferably greater than, the effective area of the siphon tube 40.
  • shroud 43 and overflow holes 51 and S2 The function of the shroud 43 and overflow holes 51 and S2 is to remelt a frozen siphon tube 40. Due to error in preheating can-sing freeze-up, or in event of a foreign body becoming lodged in the siphon tube, the flow of copper during priming may cease before full metal flow can be established. If this condition occurs, the ladle is tilted to an elevation permitting molten metal to flow over the dam .7 and around the siphon tube.
  • Freezing can also occur between the shroud 43 and the tube 40, and progressive melting is required to remelt this metal. This is accomplished by allowing the molten metal to overflow the front wall 49 of the shroud 43 and flow, in succession, from the holes 51 and 52 in the front of the shroud. The frozen metal is quite rapidly remelted and in a few minutes any frozen area in the siphon tube becomes remelted and flow conditions are established.
  • the ladle is swiveled into registry over mold 13 and is lowered until siphon tip 42 is in its normal operating position in the mold. If reciprocation of the mold is to be employed, reciprocation is commenced after swiveling the siphon in registry with the mold and the latter is partly filled.
  • the operator starts withdrawal rolls 18 to withdraw the starting bar at a pre-sclected reduced starting speed; the reduced priming flow of metal through the siphon automatically adiusting to the pro-selected starting speed when cup 42 is submerged in the molten metal.
  • the operator is ready, he increases the lowering rate of the starting bar to full running speed and at the same time raises the liquid level in ladle 11 to provide sufficient head to deliver metal at the increased rate.
  • introduction of the instant hydrogen gas is preferably begun and continued during the casting procedure, the gas being introduced at a sufficient rate during the procedure to provide the surface described earlier herein on the emerging casting.
  • a cover of solid material is placed in the mold on top of the metal therein when the latter has reached its normal operating level. Where the cover is comprised of discrete particles as is illustrated in FIG. 4, sufficient additional material of this type is added from time to time during the casting procedure to provide and maintain on the metal a protective cover of substantial thickness which generally is not less than about A; inch thick.
  • the casting 17 emerging from the mold is red hot and is rapidly chilled by the series of pressurized water sprays 89, 87, and 103-105, and the large volume of water is collected in tank 20.
  • This water is removed at any desired level as by a suitable drain line 57 and may be circulated by a circulation and pumping system, through a cooling device, and back to the water manifold 70 on the mold 13.
  • the intensity of cooling of mold 13 is so high that, even at the sustained high casting speeds obtainable with the present invention, the molten metal congeals practically as soon as it touches the mold wall, causing the edge of the crater shell 101 (see FIG. 4) to extend substantially to the free surface 24.
  • the sprays operate with such high velocity and proper tangential direction that the cooling is effected by warming the water, not by generating appreciable steam.
  • Low velocity sprays used in the uppermost position would result in steam at sufficient pressure to force its passage upward in the mold between the casting and mold wall. This results in shallow scalloping of the surface of the billet, if the steam reaches the solidifying surface. Accordingly, both pressure and direction are used to create a downward venturi action which eliminates this effect.
  • the mold is provided with a taper, most preferably employing a forced taper operation as hereinafter described.
  • the downward direction of the first and second level sprays 89, 37 is suilicient to insure overall venturi action.
  • the top level of sprays 89 applies cooling while the wall ribs 92 are still available to contact and support the crater shell. It will be understood that, even when shrinkage of the casting due to cooling causes the casting to tend to lose contact with the ribs 92, the ribs still fit the casting sufficicntly closely to remove substantial amounts of heat. Thus, at the zone defined by the ribs 92, heat is removed from the casting by Contact with both liquid medium and solid medium. In other words, the zone of cooling by contact with a solid medium overlaps the zone of cooling by a liquid medium.
  • the mold is provided with a taper, especially when high speed casting is employed and particularly in the high speed casting of low oxygen copper.
  • a taper may be a so-called natural taper or a forced taper.
  • a forced taper operation is preferred.
  • a linear casting speed is employed which, in relation to the steepness of the mold taper, is such that the shrinkage taper on the cast product, caused by the freezing and cooling of the latter, is forceably wedged against the taper on the mold wall so as to plastically deform the hot tube comprising the crater shell 101 enclosing the liquid core 162 as shown in FIG. 4.
  • Such a forced taper operation in a sense, is similar to wire-drawing. It requires the establishment of a crater shell with a long and deep V which extends in the mold at least as far as the mold taper therein, with a strong but plastic shell wall surrounding a soft liquid center, a combination that is readily deformed by pulling it through the tapered mold.
  • Such conditions are readily established in a forced taper operation due to the improved contact between shell 101 and mold wall 80 which so improves the rate of heat extraction from the shell to the mold wall that the shell wall congeals sufiiciently strong and thick to resist rupture at the high operating speeds which create the deep V.
  • the angle of the mold taper at each level in the mold should be steeper than the corresponding natural shrinkage taper on the cast product caused solely by the freezing and cooling of the latter at that level.
  • a uniform mold taper which extends throughout the entire length of the mold as illustrated by the taper of surface 80 on sleeve 94 in FIG. 4, has been found to operate satisfactorily.
  • Such a taper has the advantage of providing the proper taper angle on that part of the mold wall surrounding the free surface of the molten metal, regardless of variation in the level of this surface, thus obtaining good contact between mold Wall and crater shell even at its point of formation.
  • the reciprocation is preferably obtained by vertical reciprocation of a vertical mold on the casting as is illustrated in FIG. 1.
  • the amplitude and the frequency of reciprocation of the mold is related to the cross section being cast, the amount of taper and the casting rate.
  • higher reciprocation rates are employed with higher casting speed.
  • the ratio of reciprocation frequency (in number of cycles per minute), to casting speed (in inches per minute) should be at least about eight to one. Freferably, the ratio is 1G-l4 to l and at present, a ratio of about 11 to l is considered ideal, especially in casting low oxygen copper.
  • ratios may also be employed although the benefits obtained by higher ratios are usually not warranted by the extra wear and tear on the reciprocation mechanism.
  • a ratio of ll to l 220 cycles per minute are employed at a linear casting rate of 20 inches per minute, or 440 cycles per minute at a linear casting rate of 40 inches per minute.
  • a short stroke is generally to be preferred since this avoids excessive clearance between mold and casting on the downward portion of the stroke.
  • the stroke is about A; to H inch; :1 stroke of "i inch being most preferred.
  • stroke or cycle of a vertically reciprocated mold is meant a complete round trip movement of the mold from bottom position back to bottom position.
  • the movement is preferably simple harmonic, varying from zero speed at upper and lower ends to maximum speed between the upper and lower ends of the amplitude of movement.
  • the maximum instantaneous downward speed of the mold be greater than the uniform downward linear speed of the casting to provide a small gap between mold taper and casting taper and thus to permit a controlled amount of the cover 23 to feed down the mold wall between mold and cast product.
  • the cover is a solid particulate material, preferably one which has free flowing characteristics, especially under the casting conditions.
  • the layer 23 is a layer of discrete particles of carbonaceous material such as, for example, flake graphite, lamp black, pulverized anthracite, fine carbon particles, etc., or mixtures of such material. Fine bead-like carbon particles obtained by flash distillation of a liquid petroleum material such as still bottoms and known as Micronex beads are preferred.
  • such particulate cover material is employed in amounts suflicient to maintain a protective blanket about /2 to 2 inches thick on the top of the metal in mold 13. It is possible to employ the cover material as a means for the introduction of the instant hydrogen gas.
  • such material may be suitably treated outside the mold, as for example, with an appropriate gas, to releasably provide therein the instant hydrogen gas, and then adding the cover material to the mold and removing it therefrom at a sufficient rate to release therein, under the temperature conditions therein obtaining, the instant hydrogen gas in suflicient quantities to provide the instant results.
  • an appropriate gas to releasably provide therein the instant hydrogen gas, and then adding the cover material to the mold and removing it therefrom at a sufficient rate to release therein, under the temperature conditions therein obtaining, the instant hydrogen gas in suflicient quantities to provide the instant results.
  • the temperature of the molten metal introduced into the mold is preferably less than about 200 F. above the freezing point of the metal.
  • the temperature of the metal introduced into the mold is below about 2150 F., preferably below about 210i) F., and more preferably in the range of about 20110 to 2070 F.; a temperature of about 205l F. being at present considered ideal.
  • Example 1 Phosphorous deoxidized copper having a total oxygen content of less than .015% oxygen was cast into billets 3 inches in diameter in the casting system shown in FIG. 1 employing the mold illustrated in FIGS. 2 and 3 except that the mold was not provided with means for introducing the instant gas and none of the latter was used.
  • Sleeve 94 was machined from a block of commercial graphite and was sufliciently oversized so that when inserted into copper block 79 it was under suflicient compression to insure excellent contact between the sleeve and jacket under the casting conditions.
  • the sleeve was also provided with a uniformly converging taper of .087 inch per linear inch of the sleeve throughout the length of inner surface to provide forced taper casting of the billets at the speed employed.
  • the temperature of the copper fed into the mold was maintained at about 2050 F.
  • the level of the copper in the mold was maintained above the top of cup 42 and about 1% inches from the top of the mold but was not allowed to rise to a level closer than /2 inch from the top of the mold.
  • the mold above the level of the metal therein was kept filled with a mixture of flake graphite and Micronex heads; the mixture containing at least 25% by weight of the latter.
  • Example 2 The procedure and operating conditions described in Example 1 for the operating speed of 40 inches per minute were repeated except that, in this instance, the instant hydrogen gas was employed. Mold 13 was provided with the means for introducing the gas illustrated in FIGS. 2, 4 and 5. As illustrated by the dimensions shown in N6. 4, the top horizontal channel groove lit was located /2 inch from the top of the mold and horizontal grooves 1lll14 were located below it at spaced intervals of V2 inch; lowermost groove 114 being located 2 inches from the top of the mold. Vertical grooves 115 extending from horizontal groove 119 to 114 were spaced around the outside periphery of sleeve 94 at intervals of /2 inch. Groove was /8 inch wide and 15 .030 inch deep. Grooves 111--l15 were .030 inch wide and .030 inch deep.
  • the carbonaceous cover material mixture was added and introduction of the hydrogen gas was begun, and thereafter the casting speed was brought up to the operating speed of 40 inches per minute.
  • the level of the metal in the mold was maintained at about one and one-half inches from the top of the mold and the space in the mold above the metal was kept full with the carbonaceous cover.
  • the ratio of reciprocation frequency to casting speed was eleven to one and the stroke was 1 inch in length.
  • the hydrogen gas was commercially pure hydrogen and was continuously introduced to the mold during the casting operation at the rate of 315 cc. per minute, measured at standard conditions, i.e. room temperature and pressure, such total flow being approximately equally divided through the three passages 121 spaced equidistantly about the perimeter of block 79.
  • FIG. 10 is a scale drawing illustrating the appearance of the surface to the naked eye.
  • the ripples comprised a valley portion 140 and a relatively flat portion or land 141.
  • the specific gravity of the casting was found to be 8.92.
  • the interior of the casting was found to be free of detectable voids and had a uniform radial grain structure extending substantially to the center of the billet and the billet was free of center porosity and pipe.
  • the severed lengths of the billet were used for the production of tubes in a conventional manner by hot piercing and subsequent cold drawing to finished sizes and resulted in the production of tubes of superior quality which readily met the exacting standards required of tubing for use in air conditioning apparatus and the even more exacting standards required for rolled finned tube production.
  • Example 3 The procedure of Example 2 was repeated employing the eleven to one ratio of reciprocation frequency to casting speed. After the 40 inches per minute operating speed was reached, the casting was continued for two hours while introducing the pure hydrogen gas to the mold at the 315 cc. per minute rate as described in Example 2 to produce the regular, uniformly spaced ripples on the billet surface. The rate of introduction of the hydrogen gas was then decreased. It was found that as the rate of introduction was decreased, the surface of the emerging casting gradually and progressively deteriorated. ln thus deteriorating, the ripples on the surface of the emerging billet became lighter and less pronounced until they finally disappeared and, at a rate of gas introduction into the mold of 25 cc. per minute, the emerging surface became glassy smooth.
  • Sleeve 94 which was damaged by the rupturing of the billet, was replaced and the run was repeated as before but in this instance the rate of introduction of the gas was decreased until the emerging billet surface became glassy smooth and thereafter the rate of introduction of the gas was not further decreased. An hour after the emerging billet surface had become glassy smooth, oasting was stopped as before due to rupture of the billet.
  • Sleeve 94 was again replaced and the run repeated as before.
  • the rate of introduction of the gas was increased to the 315 cc. per minute rate which was employed initially in the run and the normal uniformly spaced ripple was quickly restored on the surface of the emerging casting.
  • the rate of introduction of the gas was then reduced until the small surface scuffs ap peared on the surface of the casting.
  • the rate of gas introduction was then increased to the 315 cc. per minute rate and the normal rippled surface was quickly restored. Thereafter the rate of gas introduction was reduced until the small visible tears appeared after which the rate was returned to the 315 cc. per minute. Again the normal ripple was quickly restored to the casting surface.
  • Sleeve 94 was again replaced and the run started and operated as before for two hours with the 315 cc. per minute rate of introduction of the gas. Thereafter, the rate of gas introduction was continuously increased. It was found that, as the rate was increased, the surface of the ripple on the emerging casting became more and more coarse until, at a rate of introduction of the gas at 850 cc. per minute, the ripple on the emerging casting began to scatter and to assume a crazy quilt pattern of surface imperfections which were perceptible to the touch and which had the appearance of cold shuts and folds at disorganized angles. With further increases in the rate of introduction, this irregular pattern increased until, at a rate of gas introduction of 1320 cc. per minute, it involved a major portion of the surface of the casting.
  • Example 4 The procedure of Example 2 was again repeated but in this instance the mold was provided with the means illustrated in FIGS. 8 and 9 for introducing the hydrogen gas, employing ports 132 which were .010 to .012 inch in diameter. It was found that the rate of introduction of the gas could be controlled to produce at will the irregular pattern of irregularities, the smooth surface, the small visi- Example 5
  • the procedure of Example 2 was repeated employing the means illustrated in FIGS. 6 and 7 for introducing the gas; the downwardly directed perforations 126 being .010 inch in diameter. Inasmuch as the mold was not shielded from the atmosphere, burning of the gas occurred at the top of the mold.
  • Example 6 The procedure of Example 2 was repeated employing the eleven to one ratio of reciprocation frequency to casting speed. After the 40 inches per minute operating speed was reached, the casting was continued for two hours while introducing the commercially pure hydrogen gas to the mold as described in Example 2 to produce the normal uniformly spaced ripple on the surface of the billet as described therein. Thereafter, the introduced hydrogen gas was progressively diluted with nitrogen gas. As the concentration of the hydrogen in the gas mixture was decreased, no apparent change took place in the character of the rippled surface until the hydrogen concentration in the gas wasreduced to about 79% by volume, thereafter the ripple became progressively more faint.
  • Example 7 The procedure of Example 2 was again repeated employing the eleven to one ratio of reciprocation to casting speed. After the 40 inches per minute casting speed was reached, the casting procedure was continued for two hours while introducing the commercially pure hydrogen gas to the mold at the 315 cc. per minute rate to produce the uniformly spaced ripple on the surface of the emerging casting described in Example 2. Thereafter, an equal how of commercially pure carbon monoxide was substituted for the commercially pure hydrogen. Within 15 minutes, the introduction of the carbon monoxide gas had to be discontinued due to the rapid deterioration of the billet surface and introduction of the pure hydrogen gas at the rate of 315 cc. per minute was immediately begun to restore the normal ripple surface to the casting.
  • Example 8 The procedure of Example 2 was repeated employing the eleven to one ratio of reciprocation frequency to casting speed. After the 40 inches per minute operating speed was reached, the casting procedure was continued for two hours while introducing the pure hydrogen gas to the mold at the 315 cc. per minute rate as described in Example 2 to produce the billet surface described therein. Thereafter, the metal level in the mold was raised and lowered from the normal level of 1% inches from the top of the mold. Higher levels caused coarsening of the rippled surface of the emerging billet, the effect being that obtained by an increase in rate of introduction of the gas at the normal level of 1% inches from the top of the mold. Lowering the level below the normal level caused the ripple on the surface to become increasingly faint; the effect being that of a decrease in the rate of introduction of the gas.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Feeding, Discharge, Calcimining, Fusing, And Gas-Generation Devices (AREA)
  • Manufacture And Refinement Of Metals (AREA)
  • Continuous Casting (AREA)
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DE19601433021 DE1433021A1 (de) 1960-01-06 1960-02-25 Verfahren zum kontinuierlichen Giessen von Metall
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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3245126A (en) * 1963-05-13 1966-04-12 American Smelting Refining Introducing hydrogen gas to the meniscus for continuously casting steel
US3315323A (en) * 1962-10-04 1967-04-25 Mannesmann Ag Method of continuous casting
US3349470A (en) * 1962-06-04 1967-10-31 Budd Co Mold for casting process
US3370641A (en) * 1965-01-11 1968-02-27 United Eng Foundry Co Reciprocating mold and coolant-support section continuous casting machine
US3395750A (en) * 1965-09-01 1968-08-06 United States Steel Corp Apparatus for displacing scum in continuous casting molds
US3451594A (en) * 1966-05-17 1969-06-24 Sigmund W Stewart Tundish nozzle construction
US3860061A (en) * 1972-08-17 1975-01-14 Voest Ag Arrangement at a continuous casting plant
US5366001A (en) * 1991-10-30 1994-11-22 Mannesmann Aktiengesellschaft Method of manufacturing rolled material from oxygen-free copper
US5464053A (en) * 1992-09-29 1995-11-07 Weber S.R.L. Process for producing rheocast ingots, particularly from which to produce high-mechanical-performance die castings
US20050101806A1 (en) * 2003-11-10 2005-05-12 Kerstin Schierle-Arndt Process for the catalytic preparation of alkali metal alkoxides
WO2005092540A1 (en) 2004-02-28 2005-10-06 Wagstaff, Inc. Direct chilled metal casting system

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SE459325B (sv) * 1982-10-20 1989-06-26 Wagstaff Engineering Inc Saett och anordning foer metallgjutning
US4598763A (en) * 1982-10-20 1986-07-08 Wagstaff Engineering, Inc. Direct chill metal casting apparatus and technique
JPH05318031A (ja) * 1992-05-12 1993-12-03 Yoshida Kogyo Kk <Ykk> 連続鋳造の冷却方法、同装置及び鋳型
US5582230A (en) * 1994-02-25 1996-12-10 Wagstaff, Inc. Direct cooled metal casting process and apparatus
WO2024007045A1 (de) * 2022-07-07 2024-01-11 Fill Gesellschaft M.B.H. Schmelzetransportvorrichtung, sowie eine mit der lanze ausgestattete schmelzetransportvorrichtung, sowie ein verfahren zum herstellen einer lanze für die schmelzetransportvorrichtung
AT526300B1 (de) * 2022-07-07 2024-08-15 Fill Gmbh Schmelzetransportvorrichtung, sowie eine mit der Lanze ausgestattete Schmelzetransportvorrichtung, sowie ein Verfahren zum Herstellen einer Lanze für die Schmelzetransportvorrichtung

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US2131307A (en) * 1935-10-25 1938-09-27 Behrendt Gerhard Chill for continuous string casting
US2135183A (en) * 1933-10-19 1938-11-01 Junghans Siegfried Process for continuous casting of metal rods
US2376518A (en) * 1942-05-29 1945-05-22 Int Nickel Co Method of casting metals
US2740117A (en) * 1953-03-05 1956-04-03 Smith George Leslie Machine for inserting handle sticks into impalable articles
US2743494A (en) * 1953-11-09 1956-05-01 Continuous Metalcast Co Inc Method for the continuous casting of metal
US2871534A (en) * 1956-04-20 1959-02-03 Wieland Werke Ag Method of continuous casting
US2946100A (en) * 1956-08-27 1960-07-26 American Smelting Refining Block graphite mold for continuous casting

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US2135183A (en) * 1933-10-19 1938-11-01 Junghans Siegfried Process for continuous casting of metal rods
US2131307A (en) * 1935-10-25 1938-09-27 Behrendt Gerhard Chill for continuous string casting
US2376518A (en) * 1942-05-29 1945-05-22 Int Nickel Co Method of casting metals
US2740117A (en) * 1953-03-05 1956-04-03 Smith George Leslie Machine for inserting handle sticks into impalable articles
US2743494A (en) * 1953-11-09 1956-05-01 Continuous Metalcast Co Inc Method for the continuous casting of metal
US2871534A (en) * 1956-04-20 1959-02-03 Wieland Werke Ag Method of continuous casting
US2946100A (en) * 1956-08-27 1960-07-26 American Smelting Refining Block graphite mold for continuous casting

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3349470A (en) * 1962-06-04 1967-10-31 Budd Co Mold for casting process
US3315323A (en) * 1962-10-04 1967-04-25 Mannesmann Ag Method of continuous casting
US3245126A (en) * 1963-05-13 1966-04-12 American Smelting Refining Introducing hydrogen gas to the meniscus for continuously casting steel
US3370641A (en) * 1965-01-11 1968-02-27 United Eng Foundry Co Reciprocating mold and coolant-support section continuous casting machine
US3395750A (en) * 1965-09-01 1968-08-06 United States Steel Corp Apparatus for displacing scum in continuous casting molds
US3451594A (en) * 1966-05-17 1969-06-24 Sigmund W Stewart Tundish nozzle construction
US3860061A (en) * 1972-08-17 1975-01-14 Voest Ag Arrangement at a continuous casting plant
US5366001A (en) * 1991-10-30 1994-11-22 Mannesmann Aktiengesellschaft Method of manufacturing rolled material from oxygen-free copper
US5464053A (en) * 1992-09-29 1995-11-07 Weber S.R.L. Process for producing rheocast ingots, particularly from which to produce high-mechanical-performance die castings
US20050101806A1 (en) * 2003-11-10 2005-05-12 Kerstin Schierle-Arndt Process for the catalytic preparation of alkali metal alkoxides
WO2005092540A1 (en) 2004-02-28 2005-10-06 Wagstaff, Inc. Direct chilled metal casting system
AU2005225367B2 (en) * 2004-02-28 2011-05-12 Wagstaff, Inc. Direct chilled metal casting system

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DE1433021A1 (de) 1968-10-10

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