US1946450A - Production of metal castings - Google Patents

Description

Feb. 6, 1934. w BAILEY 1,946,450

P RODUCTION OF METAL CASTINGS Filed July 18, 1931 2 Sheets$heet 1 I INVENTOR Richard I. ailey ATTORNEY Fe 5, 1934. R. w. BAILEY 6,

PRODUCTION OF METAL CASTINGS Filed July 18, 1931 2 Sheets-Sheet 2 IuvEN'rdR Richard W. Bailey BY ATTORNEY Patented Feb. 6, 1934 UNITED "STATES PATENT OFFICE PRODUCTION OF METAL CASTINGS Richard William Bailey, Hale, England, assignor to Associated Electrical Industries Limited, a company of Great Britain Application July 18, 1931, Serial No. 551,769, and

in Great Britain August 15, 1930 7 Claims. '(Cl. 22-200) This invention relates to the production of ingots, that complete solidification of the lower metal castings and particularly, though not expart of an ingot shall take place well inadvance clusively, to the production of ingots of cast of the solidification of the upper part and that steel. solidification shall proceed in the upward direc- In the production of cast steel ingots, particution, asthis is found to result in fewer defects in 60 larly of large size, variations in grain structure the axial region of the ingot. This can readily usually occurinvarious parts of the ingot. These be accomplished according to my invention by may result in segregation and cracks in the outer permitting the molten lead to remain in the lower parts of ingots of all shapes and of what are part of the mould for a suitable time and by then 10 called ingot comer marks in the case of ingots raising its level either by stages or continuously. 06 of square and polygonal cross section. Defects The rate of cooling may be varied at various parts also generally found in the axial region of an inof the ingot by raising and lowering the level of got, particularly in the upper part. the lead in the mould. Variation of the rate and The objectof the present invention is to reduce distribution of cooling of the ingot by the means the liability for the formation of such defects and described may be combined with heating or cool- 70 generally to produce an ingot of improved sounding of the mould whereby the rate and distribuness and quality. tion of the cooling of the ingot may be more closely According to my invention I provide for the incontrolled. For example, in order to cool the troduction, at a desired stage in the casting procmould, air may be blown over a part of the exess or even after pouring is completed, of a suitternal surface of the mould which may, for greater 76 able low melting point metal or alloy into the efiect, be formed with ribs; or the mould wall space formed between the mould and the castmay otherwise be made to present an extended ing by the contraction of the latter and/or the surface for the'extraction of heat. Similarly, in expansion of the mould. Means are also advanplace of cooling air, gaseous or other heating metageously provided whereby the height of the free dium may be employed, and when it may be neces- 80 surface of the liquid filling metal thus introduced sary, at a particular stage of the cooling, to acmay be varied as desired. By this means the centuate the relative rates of solidification at hydrostatic, pressure of the still molten metal different parts of an ingot, cooling of one part of within the outer shell of the casting where solidia mould maybe eflected in conjunction with heatfication first occurs can be counteracted at any ing of another part. The .molten filling metal 86 desired stage by the hydrostatic pressure of the maybe introduced into the mould at a certain liquid metal introduced between the shell and the point in the casting process, in some cases after mould, and, furthermore, the presence of metal the pouring is completed, for the purpose only of between the casting and the mould will increase controlling the rate of cooling, or the liquid metal the rate of cooling of the casting so that, by varymay be introduced solely for the purpose of pro- 90 ing the height of the metal introduced, the rate viding a counteracting hydrostatic pressure on and manner of cooling of the casting can be conthe outside of the casting. trolled by varying the level of the liquid metal. To provide for the introduction and withdrawal When it is desired to remove the casting from the of the liquid filling metal, an opening or port of mould the metal introduced may be run out besuitable size may be formed in the side of the 9 fore. lifting the castingmould near or at the bottom or even in the bot- In carrying out the invention in casting, for tom itself; and, if necessary, means such as chanexample, a large steel ingot, as soon as a certain nels are provided fordistributing the filling-metal amount of steel has been poured, molten metal, to the sides of the mould. In one arrangement,

lead for example, is admitted near the bottom of for example, said opening is provided with a plug 100 the mould, preferably through an openingjn the with means for screwing same in and out so as to side of the mould, at a rate which maintains. the open and close the port for the admission and level of the lead at an appropriate distance below withdrawal of the liquid filling metal as required the free surface of the steel as pouring is conand to prevent access of the moltenmetal to be tinued. When it is judged that the thickness of cast to the conduits or passages by which the 105 the shell of the ingot is such as to withstand the filling metal is introduced. Theouterside of the hydrostatic pressure of the still liquid steel in the port communicates through a conduit with 8. interior of the ingot the level of the lead may be reservoir for the liquid filling metal. The level of lowered so as to reduce the rate of cooling of the metal in the mould can be regulated by varying ingot. It is usually desired, in thecase of steel the height of molten metal in the reservoir or 10 the reservoir may be in the form of a cylinder containing 21. weight or a loosely fitted piston, the pressure of which can be varied, pressing on the upper surface of the metal therein, or there may be a suflicient space between the plunger, the axis of which would be substantially vertical, and the container to permit the former to act as a displacer causing the free surface of the liquid metal in the container and mould to rise or fall according as the plunger, is moved. In another arrangement the level of the filling metal within the mould may be varied and controlled by means of the admission plug or valve referred to and means provided for running out the filling metal. Provision must be made for maintaining the whole of the metal to be introduced in a suitable liquid condition. In order to facilitate flow of the filling metal to all faces 'of the ingot one or more distributing conduits may be provided. These would be formed preferably by removing or displacing parts of the mould wall corresponding with the conduits, the said removal taking place after the commencement of pouring of the steel and before the liquid filling metal is admitted to the mould.

The accompanyingdrawings illustrate somewhat diagrammatically and by way of example various methods by which the invention maybe carried out in practice.

Fig. 1 is an elevation, partly sectional, showing an ingot mould and means for delivering molten metal, such as lead, to the lower portion of the mould.

Figs. 2 and 3 are views similar to Fig. 1 showing.

other methods by which the melted lead may be caused to flow into the lower portion of the mould. Fig. 4 is a sectional view, drawn to an enlarged scale, of a valve, such as is indicated in Fig. 1, for

' wire 19 may be wound upon a metal drum 20, the

admitting the melted lead to the lower portion of the mould.

Fig. 5 is an elevation, the left-hand half being in section, showing a means for cooling the outside of the mould at different levels.

Referring now to Fig. 1, a mould for casting steel ingots is indicated in section at 1. The mould is illustrated as being about one-third filled with the molten steel indicated at 2, the stream of metal to be cast entering the mould being indicated at 3. -4 is a reservoir containing lead which is maintained in a melted condition by means of a furnace in the space 5 below the said reservoir. The reservoir 4 is situated at a level above that to which it is desired the liquid lead shall rise in the ingot mould. The lower end of the reservoir.

4 communicates by a pipe 6 through a valve '7 with the lower portion of the mould as shown at 8.

' The valve '7 is operated through a shaft 9 rotated by means of a hand wheel 10 from a platform 11. The outlet from the reservoir 4 to the pipe 6 is regulated by a manually operable valve indicated at 12.

On the other side of the mould is shown a standpipe 13 which communicates with the lower portion of the mould as shown at 14 through a valve 15,- which may be of a similar construction to the valve 7, said valve being operated by a shaft 16 and hand wheel 1'7.

18 is a device for indicating the level to which the metal rises in the stand-pipe l3 and thus the level to which the liquid lead has risenin the space between the casting and the side of the mould. Such an indication may be given in various ways. For example, as shown, a flexible position of the lower end of the wire in the standpipe being adjusted by rotating said drum. The wire and the metal in the stand-pipe are arranged to form part of an electric circuit including a suitable source of electricity and an alarm or signal device, so that when themetal in the stand-pipe rises to such a height as to touch the end of the wire the circuit is completed and a signal is given. It is obvious that many suitable devices can be employed, the one described being given merely as an example.

To permit the flow of melted lead from the lower part of the mould, an outlet 21 may be provided which is furnished with a shut-off cock of any suitable description. The outlet delivers a flange 23 and is provided with a branch 24 connected through a flange to the pipe 6 leading from the reservoir 4 and with an outlet 21. The barrel 22 t'erminates in an end piece 25' seated in an opening in the lower part of the mould and provided with an orifice 26 by which the interior of the barrel can communicate with the interior of the mould. Said orifice is fitted with a plug 2'7 by which it can be opened and closed. At the outer end of the barrel 22 is a'terminal gland 28 furnished with packing and which may be of any suitable construction.- The valve rod 29, which is adapted to slide in the gland 28, is connected to the plug 2'? by a socket 30 in which the inner reduced end of the plug 27 is secured by a pin 31. The outer end of the valve rod 29 is reduced in diameter and is provided with a screw thread 32 engaging with a nut 33 provided with bevel teeth 34. The nut is rotatable on the screw thread 32 by means of a' bevel gear 35 mounted on the end of the valve operating spindle 9. The nut 33 is maintained in position by means of a plate 36 supported from the barrel 22 and a sleeve 3'7, one end of which engages with the nut 33 and the other end of which engages with a bracket 38. The reduced portion of the valve rod 29 slides to and fro in an orifice in thebracket 38 and is provided with a key or feather 39 which slides in a groove in said orifice rotation of the valve rod when the nut 33 is rotated. It will be clear, without further description, that when the nut 33 is rotated in one or other direction by -means of the operating rod 9 and hand wheel 10 the plug 27 will be moved in and out of the orifice 26. A gasket 40 of asbestos or other suitable material adapted to stand the temperature of the liquid lead may be provided between the socket 30 and the inner face of the end piece 25 of the valve barrel 22. The valve 15 (Figure 1), by which the bottom of the mould is connected to the stand-pipe 13, may be of similar construction to the valve 7.

Referring again to Fig. 1, the ingot is illustrated as being about one-third poured, and its lower portion as having solidified, so that a space 41 is formed between the lower portion of the ingot and the mould dueto the contraction of the ingot and/or the expansion of the, mould. During the initial stage of the pouring the valve '7 may be maintained closed so as to prevent the metal being poured from passing out of the mould. .At a desired stage in the ipouringthe valve 7 is opened and liquid lead from the reservoir 4 is permitted to fiow into the pipe 6 by opening the valve 12 and thence into the space 41 between the lower part of the ingot and the mould. The level of the liquid in the space is regulated by operation of the valve12. In the drawings the level is shown by the line 42. The valve 15 is also opened, permitting the liquid metal to fiow into the stand-pipe 13 by which its level inside the mould is indicated as hereinbefore described. It will be understood that during the casting operation the pipe 6, the valve 7 and the stand-pipe 13, with its valve 15 will be maintained at such a temperature as will permit of the flow of the liquid lead from the reservoir 4 to the bottom of the mould, into the standpipe 13 or through the outlet 21 as desired. This may be done by external heating, for example by means of gas jets suitably applied, not shown in the drawings.

The liquid filling metal may be admitted to the mould in this manner at any desired stage in the pouring, or even after the pouring is finished, in order to regulate the cooling and/or to supply a suitable hydrostatic pressure to the outside of the ingot as desired.

Notwithstanding that the lower part of the ingot or casting is resting on the base of the mould it is found that the liquid filling metal will pene-.

trate to the space between the ingot and the mould without difiiculty. In some cases means such as channels, not shown in the drawings, may be provided for distributing the filling metal to the sides of the mould.

Referring now to Fig. 2, a. mould 1, of which the lower portion is provided with valves such as valves '7 and 15 which may be similar to the valves 7 and 15 hereinbefore described and illustrated in detail in Fig. 4, but which are of somewhat different external appearance, is shown. The liquid low-melting metal is supplied to the lower portion of the mould from a reservoir 45 which is located below the valve '7 and connected to said valve by a pipe 47. The liquid low-melting metal is forced by pressure of a suitable gas from the reservoir 45 into the mould by way of the pipe 47 and valve '7 The gas, for example nitrogen, is supplied to the reservoir 45 from a gas bottle 43, connected to the upper end of the reservoir by a pipe 44 equipped with a regulating valve 44 The low melting point metal, for example lead, may be maintained in a molten condition by a furnace, not shown, located in the space 46 below the reservoir 45. The reservoir 45 is provided with a pressure gauge 48.

The stand-pipe in this instance may be dispensed with and the height to which the lead rises in the mould may be estimated from the pressure shown on the gauge 48. Instead of permitting the lead to escape through a pipe, such as the pipe 21, Figure 1, it may be permitted to run back into the reservoir 45 by reducing the height and is provided with a ram or plunger 50 of somewhat smaller cross-sectional d mensions than the reservoir so that metal may rise freely in the space between the plunger and the walls .of the reservoir. It will be clear that, by raising and lowering the plunger 50 in the reservoir, the

low melting point metal may be forced through the pipe 47 into and out of the lower portion of the mould between the ingot and the mould as desired. The level of the metal in the mould, as shown by the line 42, will obviously be the same as that in the reservoir 49. In this case also the standpipe for indicating the level may also be dispensed with.

In Fig. 5 means are shown for cooling the mould externally. For this purpose the mould 51, which may be of any desired form internally, is provided on its exterior with ribs or fins 52 to facilita'e cooling. A muif 53, made of sheet metal, has its upper and lower plates 54, 55 shaped to cooperate with the ribs 52 and is adapted to be moved up and down the mould as desired by means of chains or wire ropes 56. The muff is provided with an inlet 58 and an outlet 57-for the admission and discharge of cooling air which is caused to flow, preferably in an upward direction, over the mould thereby causing a greater cooling eflect at that portion of the mould to which the muff is applied than at other portions. The cooling effect will also be greater at the lower part of the muif or where the cold air is admitted. In some cases the upper plate 54 of the muff may be omitted and the air therein may discharge directly into the atmosphere. Arrangements such as shown in Fig. 5 for cooling the mould at some parts more than at others may, if desired, be

employed in conjunction with arrangements for admitting liquid metal to the lower part of the mould as previously described.

In some cases means may be employed for heating the upper end of the ingot; for example the head part of the mould indicated at 59 in the drawings may be lined with a refractory material of low thermal conductivity supplemented by heatingimeans. In one arrangement the head is made with double walls, the annular space I between the walls constituting a heating chamber which may conveniently be heated by gaseous or liquid fuel. In some cases, for example in the case of very long ingots or castings, it may be desirable to apply heating means to the upper part of the ingot as distinct from the head.

In some cases after the wall of the ingot or casting has been solidified to a sufiicient thickness it may be desirable to retard the rate of cooling of the upper part of the ingot while in the lower portion the rate of extraction of heat is intensified, for examp e by means such as above described with reference to Fig. 5. In this case above a cooling jacket such as shown in Fig. 5

a heat insulating jacket or mufi may be employed which may be raised with the cooling mufi during the operation of freezing the ingot or casting solid from the bottom upwards. Furthermore after the lower part of an ingot or casting has become solid it may be desired to retard the cooling to prevent the development of.

high internal stress. In this case heat insulating means or heating means may be applied below the cooling jacket or muff.

Although I have herein described various methods of carrying out the invention and illustrated various constructions in the drawings, it will be understood that the invention is not limited to any particular construction of mould or accessary apparatus. Furthermoreit will be understood that the invention is not limited to the casting of ingots or pieces of simple shape, but may be'employed for the purpose ofincreasing the soundness and quality of castings of other metals than steel and of larger or more complex mitting the poured metal to partially solidify,

and introducing between at least a part of the solidified surface of the metal and the mold fluid metallic substance having a melting point lower than that of the metal being cast.

2. A process of producing metal castings, comprising pouring molten metal into a mold, and in introducing between at least a part of the metal and the mold, during the pouring operation and after partial solidification of a poured portion of the metal, fluid metallic substance having a melt! ing point lower than that of the metal being cast.

3. A process of producing metal castings, comprising pouring molten metal into a mold, and in introducing between at least a part of the metal and the mold, after the pouring operation and partial solidification of the metal, fluid metallic substance, having a melting point lower than that of the metal being cast.

4. A process of producing metal castings, comprising pouring molten metal into a mold, permitting the poured metal to partially solidify, in-

troducing between at least a part of the solidified surface of the metal and the mold fluid metallic substance having a melting point lower than that of the metal being cast, and. varying the level of the metallic substance in the mold.

5. A process of producing metal castings, comprising pouring molten metal into a mold, permitting the poured metal to partially solidify and introducing molten lead between the mold and at least a part of the solidified surface of the metal being cast.

6. A process of producing metal castings, comprising pouring molten metal into a mold, permitting the poured metal to partially solidifiy, introducing between at least a part of the solidified surface of the metal and mold fluid metallic substance having a melting point lower than that

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