US1298034A - Apparatus for teeming ingot-molds. - Google Patents

Description

E. GATHMANN.

APPARATUS FOR TEEMNG INGOT MOLDS.

APPLICATION FILI-: DECJSl 15H8.`

Patented Mar. 25, 1919.

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EMIL GATHMANN, OF BALTIMORE, MARYLAND.

APPARATUS FOR TEEMING INGOT-MOLDS.

Application led December 6, 1918.

To all whom, t may concern.'

Be it known that I, EMiL GATHMANN, a citizen of the United States, residing in Baltimore, State of Maryland, have invented certain new and useful Improvements in Apparatus for T eeming Ingot-Molds, of which the following is a specification.

This invention relates to the casting of metal ingot's 'or the like and particularly to the pouring or teeming of metallic ingot molds.

Heretofore the common practice has been to teem a series of molds from a ladle of large size containing sufficient molten metal to fill a plurality of molds one after the other and someattempts have been made to fill two or more molds simultaneously from the same ladle, but this latter method has not been successful inasmuch as often one mold was lfilled before the other or others owing to irregularities in the flow of metal through the passages leading from the ladle; therefore, the common practice is to fill the molds separately, the metal passing from the ladle through a valve-controlled nozzle in a large stream and with high velocity under the great hydraulic pressure of the large quantity of molten meta-l in the ladle. This stream of metal'at rst strikes the bottom of the mold chamber and often injures it and furthermore during the entire period t of teeming the metal splashes violently causing it to mingle with air and to strike with great force against the side walls of the mold chamber in such manner as to cut the mold walls and to cause the molten metal to weld to said walls and thus not only impede the proper shrinking of the ingot away from said walls and also the easy stripping of the ingot from the mold, but it often results in producing what are called cold shuts or scabs on the ingot which are serious de fects that cannot be gemedied by subsequent processes and often result in imperfect products from the ingots.

It is also well known that during the teeming of a mold the molten metal as it falls into the mold chamber is deflected and driven with considerable force against the side walls-of the mold and a skin is formed on these walls above the level of the more quiet metal in the mold. This skin is somewhat mushy or soft and often during the Specification of Letters Patent.

Patented Mar. 25, 11919.

serial No. 265,582.

it enters the mold chamber will be reduced,

the Object being to reduce or prevent the formation of cold shuts or scabs and to otherwise remedy the difficulties above mentioned. Mold teeming devices of this class have, however', in all cases been in the form of portable containers which were interposed between'the ladle proper and the top of the mold, the metal flowing freely from the nozzle of the ladle into the container which Was provided with a plurality of openings through which the metal was delivered to the mold. In such cases the hydraulic pressure of the metal` in the ladle was only used to force the metal through the outlet of the ladle, none of such pressure being utilized for forcing metal in a subdivided condition or with reduced velocity into the mold, therefore the speed of delivery was unduly reduced and furthermore the metal was unduly cooled .owing to thefact that it passed through an open air space i between the nozzle and the perforated re ceptable thereunder. In such cases also it was not possible to pass the molten metal v uniformly through all the openings or perforations in the receptacle and it was not possible to regulate the flow of the metal through said openings. Furthermore, owing to this irregularity in the flow of metal through the perforated receptacle the metal often became thickened or mushy and some or all of the openings would be closed, there fore this method of pouring molds has never, so far as I am aware, been used, certainly its use has not been general.

According to my invention, I reduce the velocity without materially reducing the volume of metal discharged from the ladle into v y the mold and I utilize the hydraulic pres sure of the mass of molten metal in the ladle to force the metal not only with sufficient velocity and with the required volume from the ladle but also to force it with reduced velocity and substantially the saine volume into the mold chamber. In this way a much quieter pouring of the mold is effected without any loss of time. Preferably the solid stream of molten metal passing from 'the ladle through the valve-controlled orifice is made to impinge upon a battling devicev arranged in a chamber which distributes or directs the molten metal with its high velocity thus modilied to a 'series of discharge openings through which the metal passes in a plurality of relatively small streams each of which individually is of smaller cross section than that of' the outlet opening of the ladle but which are collectively of greater cross section than said outlet opening. In this way the velocity or speed of the molten metal coming from the ladle is greatly reduced and yet the volume of metal passing' from the ladle is not materially changed. Therefore the ladle can be emptied at the same speed as before but with the additional advantages above specified. Furthermore, the metal 'passingl through the delivery openings is constantly under hydraulic pressure which insures the constant and unimpeded delivery of the metal. which has no chance to cool or solidify in such manner as to delay the operation.

In carrying out my invention, I preferably employ `a ladle or container of sutil cient capacity to till in succession a plurality of molds and in the bottom of the ladle I provide an outlet opening controlled by a valve vor stopper' which may be of usual construction. The metal passes through the outlet opening in a. relatively large stream but instead of passing directly into the mold as heretofore it enters what I call a distri'- bution chamber of larger capacity than the outlet of the ladle and containing a baiiiing device which receives the stream of molten metal, changes its velocity and deiiects the metal or distributes it to a series of discharge openings through which the metal passes to the. mold with reduced velocity but under hydraulic pressure and yet in #such manner as to teem the mold in the required tiine without danger of the metal cooling or solidifying in the ladle before it is emptied. The metal through the discharge openings that ity enters the mold chamber in a much quieter manner than heretofore causing less boiling or splashing and preventing the cutting or breaking of the mold walls or the skin forming on the sides thereof and also preventing the welding of metal to the mold walls which was a serious defect in methods heretofore employed. Other features of ymy invention will be hereinafter more fully described.

In the accompanying drawings Figure l is a sectional view of a metallic ingot mold and a ladle for teeming 'the mold is so deliveredv constructed in accordance with my invention.

Fig. 2 shows a section on the' line 2 2 of Fig. l.

Fig. 3 shows a section on the line 3 3 of Fig. l.

Fig. 4 is a. detail view in perspective intended to illustrate particularly the construction of that part of the nozzle in which the velocity of the stream of metal passing from the ladle. is reduced and the metal is deflected and distributed to the discharge openings of the nozzle.

Referring to Fig. 1, I have shown a well known form of mold A, resting on a stool or base A. It will be observed that the walls of the mold A are thinner in their upper portions than in their lower portions so that the formation of pipe in the ingot is reduced or eliminated in a manner now well known, but it will be understood that my invention may be applied to molds of other construction.

The ladle B is in general of well known construction except that the devices applied to the outlet of the ladle are made in accor ance with my invention. As usual, the ladle comprises an outer casing or shell l) of metal and a lining of refractory material, such as tire brick, and the ladle is provided with ears b2 which may be engaged by suitable devices 3 for supporting the ladle and these devices may be connected with'l cranes or other mechanism for moving the ladle from place to place as desired. An opening a; is formed in the bottom of the ladle and is preferably centrally located as indicated, and this opening is controlled by a valve or stopper Bv of well known construction which may be provided with any suitable devices for. operating it. The devices applied to the outlet opening constitute generally what may be termed a nozzle. In Fig. l this nozzle comprises a metallic casing I) which may be detachably connected with the bottom of the ladle by bolts or other suitable devices d. rlhis casing incloses and supports a block lll of refractory material, chambered and provided with passages for the molten metal. The part d projects into the opening and is suitably formed to provide a valve seat e for the valve or stopper B. Below the valve seat there is a passage1 of relatively large cross section through which. the molten metal passes from the ladle and this may be termed the outlet of the ladle. Said passage f delivers to a chamber G, the preferred form of which is clearly indicated in Fig. 4 of the drawings and is also indicated in other igures. This chamber I call the distribution chamber inasmuch as it divides the stream of metal flowing through the pas sage 7 and directs the metal to a plurality of delivery openings f/ each of which is of smaller cross section than the outlet passage Preferably these passages g are arranged in an annular series and While each one is of less cross sectional area than the passage f, collectively their cross sectional area is much greater; preferably about 50% or more greater. Within the distribution chamber is located a baffling device H Which assists in distributing or directing the metal to the discharge openings g and which also receives the full force or impact of the stream lof metal passing from the ladle and serves to reduce its velocity While at the same time deflecting the metal in the manner before specified. l

While the velocity of the metal passing through the outlet openings g is greatly reduced it is forced through the outlet openings by the great hydraulic force or pressure *of the mass of metal in the ladle, this pressure being suiicient at all times to deliver the metal with such speed as to prevent the cooling or the solidifying thereof before it is discharged into the moldchamber-- As before stated l preferably divide the stream of metal passing from the ladle into a plurality of relatively small streams arranged in an annular series but it is not necessary that said openings should be so arranged, and the number of such openings is not essential so far as some features of my invention are concerned, it being important in this connection merely to so reduce the velocity of the metal passing from the ladle and before its, entry into the mold chamber that it shall not injure the Walls of the mold or cut away or injure the skin of the ingot during its process of formation. It is important, however, in this connection, for the reasons before stated, that the metal shall be forced with reduced velocity by the hydraulic pressure of molten metal in the ladle and that the passage of a relatively large solid stream of molten metal 'from the ladle to the mold should be avoided.

The passages for the metal from the ladle to the mold are preferably all formed in a single block E of refractory material, as illustrated in Fig. l, and the Walls of these passages are se, disposed as to avoid the formation of 'shoulders or corners which.

would unduly impede the iiow of the metal through the nozzle. Preferably an annular series of discharge openings is provided but these passages need not necessarily be arranged in an annular series and furthermore they may be merged and a similar result obtained, z'. e. the single solid stream of metal will beso changed as to reduce the velocity of the metal entering the mold and furthermore the force or impact of the metal will be reduced or distributed, resulting in a much quieter pouring operation Without any loss of time in filling the mold.

l preferably so proportion the cross sectional area of the passages or channels in the nozzle that the combined area of the discharge openings is larger by approximately 50% or more than that part of the nozzle Which communicates directly with the ladle. I may therefore use any desired number of discharge openings in the nozzle so long as they are of such size when combined as to reduce the velocity of the metal passing through the nozzle Without materially decreasing the volume of metal delivered during any period.

It will be observed by reference to Fig. l that the solid stream of metal passing through the passage ,f is enlarged into a substantially cylindrical or hollow body of metal entering the mold, and While several distinct streams of metal are included in this cylindrical body it is obvious that they may be merged and yet produce a satisfactory result because in either case the velocity of the metal entering the mold isreduced, the impact of met-al on the metal inthe mold is distributed and the violent disturbances heretofore encountered are avoided.l Furthermore, in all cases the' direct impact of the metal assing from. the ladle 'is received by the ba ing device in the distribution chamber. This serves also to reduce the velocity of the metal and yet itdoes not impede the volume of metal delivered by the nozzle. I

The size or cross sectional area of the intake passage in the nozzle is in present practice, as is Well known, usually made as small as will, with the required factor of safety, 100 drain the ,ladle of its molten liquid burden of metal Within the time period necessary to `teem-or cast a certain number of ingots. For example, a ladle filled with a burden of 5() tons of steel should be fitted with a 105 discharge opening of 2 inch diameter for filling each of 25 ingot molds in succession with 2 tons of molten steel; the time of teeming or casting each individual ingot being approximately one minute, the vactual pouring period is25 minutes, the ladle or the molds being moved' into teeming or casting position for each ingot made; one-fifth of ay minute or collectively 5 minutes being taken for thus filling a group of Q5 molds. 115 By experiment it has been* found that a ladle With a burden of 50 tons of molten liquid steel will retain the steel in its molten condition if placed in the ladle at a suitable temperature from the melting furnace 120" for a period of from 35 to 45 minutes, a factor of safety as to the time of teeming or casting throughA a 2 inch nozzle from 5A to l0 minutes is thus obtained. The importance of not unduly increasing the time of teeming or casting the burden of molten steel from a ladle will thus be understood from theeXample above explained, and it Will also be understood that it is impossible or improper to greatly decrease the volume or weight of metalteemed from the ladle within a specified time. A nozzle made in accordance with my invention is adapted to be irmly fixed or secured to the ladle while the latter is emptyV and reasonably cool. VA new nozzle is required for every second to sixth heat of the molten metal carried by the ladle, -the life of the nozzle depending considerably upon the grade of metal being cast, its temperature and other factors well known to those skilled in the art so thatthe nozzle as a whole. while adapted to be firmly secured to the ladle, is detachably connected therewith.

The ladle equipped with a nozzle made in 4accordance with my invention is operated. in

precisely the same way as those`usuall57 employed, the stopper B being made to control the delivery of the metal from the ladle. As

'the molten metal enters the mold that portion which comes in Contact with the relatively cool inclosing mold walls and stool'is very rapidly frozen vor solidilied intoa semisolid or mushy condition forming what is termed the relatively thinskin of the ingot within which the inner body of the ingot later on solidiies or freezes. As the pouring operation continues and the interior of the' ingot is formed the shin gradually thickens and becomes more solid and strong.

The vertical walls or initial skin of the ingot grows as the ingot increases in height and although these walls are semi-.solid they are extremely tender or in a mushy state due to the ,intense heat of the still liquid interior mass of the ingot. lt is eidreniely important and well known to those skilled in the art that this shin of the ingot should not be disrupted or broken as such brealis of the mushy skin or semi-solid skin will not properly heal or close and if brealts or cracks are once formed they usually remain as surface defects in otherwise sound, homogeneous ingots or in the finished product.

l have found that one of the primary causes of such surface defects in ngots is due to the improper teeming from the ladle to the'mold of a solid stream with high velocity which may in a great way be remedied by more quietly and gently delivering the liquid metal into the mold cavity than had heretofore been done.

It is known that liquid steel weighs approximately one-quarter pound per cubic inch, and the cross section of a two-inch stream ,of liquid steel passing from a. twoinch nozzle will thus weight Bil-ltimes 12)(.25 per foot of height or approximately l0 pounds. As the ladle is frequently iilled with l0, 12 or more feet depth of steel a incense pounds is imparted to the descendino column of the highly heated liquid steel. Cllhe impact of this mass of liquid steel is taken, first by the stool or bottom closure of the mold and second by thevbody of liquid steel which has already entered the mold and which forms the impacting cushion as the ingot grows or increases in size in the mold cavity 'due to the incoming liquidmetal from the ladle. As the force of impact of any body is, as the square ofthe velocity, times the weight of the said body the reduction of the velocity of the impacting body is of prime importance in cutting down the energy of the blow. This-velocity, due to the height of liquid steel in the ladle and the hydraulic pressure caused thereby, is brought under control by my improvements in which I suitably proportion the discharge area of the nozzle to the area of the outlet passage from the ladle.

F or example, if the outlet from the ladle has a cross section of two square inches and the delivery openings have a cross section of four square inches and assuming the velocity of stream flowing through the out let ofthe ladle as lO feet per second the same volume or amount in weight of metal will iiow through the vfour square inch delivery openings at a velocity of 5 feet per second, provided of course the direction of the stream from the inlet to the nozzle is first diverted by means of a ballliner device or by means. of a distribution chamber having a larger cross sectional area. The actual impact value of a 5 foot per second and a l@ foot per second stream is obviously as 5 squared is to l0 squared or as l is to el for the same volume or weight of the metal stream.

Fig. iindicates how the mushy skin is formed in the mold and this is incident to allcasting operations of the kind to which my invention relates. Where the velocity of the metal entering the mold is reduced in the manner before described, and especially where the solid stream is divided into a plurality of streams, as indicated in the drawings, the breaking down or injury to the skin is avoided or greatly reduced. As in dica-ted in the drawings, where a plurality, of streams are employed they are preferably so located as to he grouped around the longitudinal axis of the mold because a direct impact of even a relatively small stream would injure or break through the mush-y walls or skins while the ingot is in process of formation. Direct impact or even deflected impact of a single large stream with the walls of the mold cavity either above or below the mushy skin of the ingot during the process of ingot formation is also liable to cause serious defects in the walls of the even actual welding inthe ingot surface at llt) various points to the mold walls thus preventing the ingot from freely shrinking during the cooling or solidication thereof and consequently causing tears or cracks in the surface of the skin of the ingot.

It will be observed that the discharge openings or passages g are arranged` vertically and should be at least approximately vertical in order that the streams of metal entering the mold shall be delivered in a substantially vertical direction. If this were not so the metal would strike against the side walls of the mold and defeat the objects of my invention, for the reasons hereinbefore explained.

In the drawings, I have assumed that the cross sectional areaof the passage f has a diameter of two inches, while the discharge openings g are each one inch in diameter so that the cross sectional area of the resulting discharge opening is double that ofthe outlet opening f, but as before explained this relative arrangement is not essential but it is important that the area of discharge from "the nozzle should lbe greater thanthe area of the entrance thereto.

My invention involves not only improvements in the apparatus for teeming molds or in the nozzle for directing the molten metal from the ladle to the mold but it also involves a new method of teeming molds and such method is claimed in my application for Patent No. 265,583, filed Dec. 6, 1918.

I claim as my invention:

1. Apparatus forteeming an ingot mold, comprising a ladle or container of molten metal 4and a valve-controlled nozzle therefor provided with means for discharging molten metal at reduced velocity and with increased area in an approximately vertical direction into a mold without materially reducing the volume of metal delivered thereto.

2. Apparatus for teeming an ingot mold, comprising a ladle or container of molten metal, and a valve-controlled delivery nozzle therefor provided with a passage of relatively large cross sectional area for the liow of metal from the ladle into the nozzle, an expansion chamber into which said passage delivers and an outlet from said chamber through which the metal passes in an approximately vertical direction to the mold which is of materially greater cross sectional area than the inlet passage to the nozzle, whereby the metal is delivered to the mold from the nozzle in substantially the same volume that itentered the nozzle but at greatly .reduced velocity.

3. Apparatus for teeming an ingot mold, comprising a ladle or container of molten metal, and a valvecontrolled delivery nozzle therefor provided with a passage of relatively large cross sectional area through inlet passage but the cross sectional area of said passages collectively being materially greater than the cross sectional area of said inlet passage in order that the metal may be delivered Yto the mold at a mate- .rially reduced velocity as compared with the velocity of the metal entering the nozzle. 4. Apparatus for teeming an ingot mold,

comprising a ladle or container of molten metal, and a delivery nozzle therefor provided with inlet and discharge passages of different cross sectional areas, and an expansion chamber between the inlet and discharge passages of greater cross sectional area than the inlet passage, said discharge passages being arranged substantially vertically in order that the metal may be delivered to the mold in an approximately vertical direction. 1 5. Apparatus for lteeming an ingot mold, comprisinga ladle or container ofV molten metal" vand a delivery nozzle therefor provided with .an inlet passage of relatively large cross sectional area, a chamber of still greater cross sectional area at the inner end of said inletpassage, a device in said chamber arranged opposite the inlet passage to receive the impact of iniowing metal, and a pluralitv of discharge passages communicating with said chamber which are arranged approximately vertically and from which the metal passes in an approximately vertical direction into the mold chamber at reduced velocity as compared with the velocitv of the metal entering the nozzle.

6. Apparatus for teeming an ingot mold,

comprising a ladle or container of molten metal and a delivery nozzle thereforprovided with an inlet passage through which metal passes from the ladle to the nozzle, and a plurality of vertically arranged discharge passages connected with said inlet passage, each of which passages is of less cross Asectional area than the inlet passage but whose combined cross sectional area 11S materially greater than said inlet passage and which deliver directly in a substantially vertical direction to the central portion of the mold chamber without coming in contact with the sidewalls thereof.

7. A nozzle for teeming ladles havin'g an upper portion adapted to enter an opening in the bottom of the ladle, an integral lower portion through 'which the molten metal is chamber.

8. A nozzle for metal-teeming ladles having an upper portion adapted to connect with the bottom of the ladle, a lower por tion through which the molten metal is discharged into themold and which is provided With a series of vertically arranged passages, and an intermediate portion provided With an expansion chamber through which molten metal passes from the ladle to the discharge openings of the nozzle.

9. A nozzle for teeming ladies made of refractory material and having an upper portion adapted to connect With the bottom of the ladle, a lower portion through which the molten metal is discharged into the mold and which is provided with a series of vertically arranged passages, and an intermediate portion provided with an expansion chamber through which molten metal passes from the ladle to the discharge openings of the nozzle, in combination with a, metallic container for said refractory material adapted to be secured to the ladle and which is open at the bottom to permit the passage of metal through it.

10. A nozzle for teeming ladles made of refractory material and having an upper portion adapted to connect with the bottom of the ladle, a lower portion. through which the molten metal is discharged into the mold and which is provided with a series of vertically arranged passages, and an intermediate portion provided with an expansion chamber through which molten metal passes from the ladle tothe discharge passages of the nozzle, in combination with a metallic container' for said refractory material adapted to be secured to the ladle and which is provided in its bottom portion with a series of openings registering with the discharge passages in the nozzle.

In testimony whereof, I have hereunto subscribed my name.

EMIL GATHMANN.

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