DE1164605B - Method and device for the falling casting of metal - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY GERMAN 4057WW PATENT OFFICE Internat. Class: B 22 d

EDITORIAL

Number:
File number:
Registration date:
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German class: 31c-12/01

Jefz »Kl, M, ¹ V * Pat. BI.VÖ 12 1.

1164 605 4 ^ Li ⁴
U 7463 VI a / 31 c
September 16, 1960
March 5, 1964

The present invention relates to a method and an apparatus for falling casting Metal from a ladle into a casting mold with the exclusion of the atmosphere on the Metal by inert gas.

Generally, a ladle containing the molten steel is used with a bottom outlet above arranged in a mold. The pouring stream is then directed into the mold until an appropriate one Amount is poured, whereupon the pouring flow is interrupted and the ladle to the next Shape is moved. When the pouring stream hits the bottom of the mold for the first time, the liquid splashes Metal against the walls of the mold, to which the metal splashes adhere and solidify. Located in the Form air, the metal splashes oxidize, and when the pouring level rises, the solidified ones melt Metal splashes do not reappear to merge with the molten stream, but adhere continue to adhere to the shape and form poorly bound scabs on the sides of the cast Blocks.

Another difficulty encountered with conventional casting technology is adsorption of Oxygen from the surrounding atmosphere through the molten substance flowing out of the ladle Current. The oxides resulting from such adsorption are all over the block distributed and lead to metallurgical defects affecting the mechanical, chemical and electrical Reduce the properties of the product.

High purity metal is required, for example in the manufacture of precisely sized aircraft parts, the inclusions mentioned above are in the Steel is highly undesirable. Manufacturers and designers of aircraft parts continue to demand cleaner and inclusion-free steels.

The object of the invention is the complete shielding of the falling pouring stream and into the Metal reaching the casting mold against any influence of oxygen in the air by means of a process, This is unlimited for all casting ladles and casting molds with the use of less mechanical aids can be applied.

According to the invention, it is proposed to fill the casting mold with protective gas before casting, which is displaced by the incoming pouring stream and envelops it and covers the pouring level, at the same time the pouring stream below the bottom outlet of the pouring ladle is enveloped by a further protective gas stream directed at it and both protective gas streams become one of the beam method and apparatus for falling
Casting of metal

Applicant:

Union Carbide Corporation, New York, N.Y.

(V. SL A.)

Representative:

H. Kundoch, lawyer,
Rodenkirchen near Cologne, Auenweg 14

Named as inventor:
Leo Fred Keel, Emsworth, Pittsburgh, Pa.,
Maurice Frederick Hoffmann, Whippany, NJ,
Ronald Jay McCullough, Hazlet, NJ,
Peter Anthony McCormack,
Corona del Mar, Calif. (V. St. Α.),
Ronald Leadrew William Hohnes,
Downsyiew, Ontario (Canada)

Claimed priority:

V. St. ν. America September 16, 1959

(No. 840 270)

Combine the protective gas jacket encasing it over its entire length.

Measures to reduce the access of air to the pouring stream and / or the liquid metal in the mold have been made in large numbers for decades, but could Do not enforce a measure on a larger scale in practice, since in most cases only success low or the required expenditure on mechanical devices and protective gas too extensive is.

The well-known casting of metal in a vacuum results in a suppression of the reaction of the liquid metal with the oxygen in the air. However, performing this procedure requires elaborate facilities. In these devices it is known to connect to the vacuum chamber in the passage for the metal to be cast a sealing membrane, e.g. B. made of sheet steel or another Metal, to be provided, which only melts when the steel is filled.

409 537/420

i 164 605

3 4

It has also already been suggested that, as shown in FIG. 1 is a longitudinal section of a mold that

the pouring stream is already partially filled with protective gas during tapping and pouring,

with a jacket of protective gas, e.g. hydrogen, Fig. 2 partially in section a ladle and

To surround nitrogen, argon, coke oven gas, or the like. Casting mold before the casting process,

However, this only led to a conditional improvement. 3 partially in section the device according to

tion, since the pouring stream in the casting mold with the air F i g. 2 during the casting process,

comes into contact. F i g. 4 is a view on an enlarged scale

It is also known, in the space between along the line 4-4 of FIG. 1 of the distributor head,

Casting ladle and casting mold for better shielding F i g. 5 shows a partial section on an enlarged scale

of the pouring stream with protective gas a tubular io along the line 5-5 according to FIG. 3 and

Provide intermediate piece, which by means of sand cups F i g. 6 a longitudinal view, partly in section,

compared to the atmosphere and ladle as well as a modified embodiment of the device

Casting mold is sealed. When casting the metal device according to the invention.

If the protective gas is in the intermediate piece, e.g. As shown in Fig. 2, the device

Argon, introduced under pressure, based on FIG. 15 for carrying out the method according to the invention

Injector effect of the falling pouring stream into a pouring ladle 10 for pouring molten metal

Casting mold arrives. Here are the practical tails on too. In the lower part of the ladle is a

Application of the method aggravating mecha- floor outlet 12 is provided, from which a metal stream

Niche devices for shielding the liquid in a casting mold 14 arranged vertically below

metal required. so is judged. A pipe section 16 is on the lower

The filling of the mold before the pouring side of the ladle is releasably attached, surrounds the

with a protective gas is known. The floor outlet 12 is hereby and forms a protective space 17.

Inert gas introduced into the casting mold from below and the pipe section 16 can, as in detail in

the supply of protective gas interrupted during casting, FIG. 5, with outward

in order to create an overpressure in the casting mold 25 sets 18 provided in suitable recesses

to avoid. Since the mold on the pouring side fits within corresponding approaches 20,

no drains that are attached to the ladle and prevent the gas from flowing out. The pipe section

has cover, the gas flows when pouring 16 is on the underside of the ladle to

Out of the mold into the open in a very short time, every possible space in between as small as possible

and the oxygen in the air can hold itself during the large- 30, but there would be a certain distance between

th part of the casting process unhindered with the pipe section and the pouring ladle

The pouring stream and the part in the casting mold affect the process, but only the

connect liquid metal. to shield the pouring stream 19 required

Another method provides for the mold amount of inert gas, e.g. B. Argon, increase,

to complete the atmosphere and the 35 The upper end of the pipe part 16 is on the

Casting mold provided against the ingress of air with an inside with a ring line 24, which

Has protective gas with complete displacement in a gas channel. One through the wall

The atmosphere located in the casting mold with a gas inlet extending through the pipe section

to be filled with pressure and when the pouring jet 26 falls it connects the gas channel with a protective gas source,

in the mold a barrier in the inlet of the mold 40. A plurality of openings 28 are in the line

to be lifted in such a way that the flow from the mold is directed towards the bottom outlet 12, so that the

Mende shielding gas envelops the pouring stream. Inert gas effectively displace the air and that

According to a further proposal of the invention, pipe section 16 can be filled.

which the pouring stream at its exit from the corresponding F i g. 2, the dimensions of the protective gas pipe section 16 enveloping the bottom outlet of the pouring ladle depend on various factors: downstream directed and meets with the a) the diameter D of the bottom outlet, b) the downward flow of the flow from the casting mold the divergence of the pouring jet and c) the inert gas forced above the mold. The fact that the upper edge of the pipe section is exactly through causes two mutually flowing parts of the surface of the pouring ladle to fit and should be in the space between the casting mold 50, in order to keep the gap between them to a minimum, and protective gas streams combining the pouring head The effectiveness of the argon atmosphere in protecting the entire surface of the pouring stream depends primarily on the position of the liquid metal in relation to the atmosphere - the ring line, which should be as close as possible to the pouring screens, without blocking them touch. The apparatus for carrying out the Inventions 55 If, for example Bodenauslaßöffnungen of the method according is characterized used by about 3 to 8 cm diameter disposed at the bottom of the ladle housing diameter D should preferably be between unge-nozzle ring and this ring of nozzles surrounding, ferry between 12 and 40 cm. The best protection parallel to the pouring stream extending pipe ensuring the height h of the pipe section should piece to guide the upper shielding gas flow. 60 be chosen that the lower edge of the pipe-expediently, the casting mold is closed at the top with a piece no further than about 10 cm below a cover that extends an opening to the bottom outlet. The preferred ratio of introduction of a distributor head provided with the maximum height h to the diameter D should be 1 gas line. do not exceed.

Other features, advantages and applications 65 The most suitable location of the ring line 24 within

Possibilities of the invention result from the loading of the pipe section 16 to the space 17 in a suitable

Writing of exemplary embodiments in a combined way to fill with protective gas, is through the vertical

hang with the drawings. It shows the distance between the floor outlet and the

Underside of the ladle determined. This distance should be maintained so that when the pipe section 16 rests against the underside of the ladle, the line 24 is approximately 0.6 cm below the bottom outlet is located.

As illustrated in the figures, the casting mold 14 essentially has an open-topped container to absorb the molten metal during cooling and solidification. the Casting mold can be provided to form blocks that are subsequently rolled or otherwise Way to be deformed. However, the method according to the invention can also be used for casting molds Use the production of sand castings in the usual foundry process.

A mold particularly suitable for the method according to the invention has an inlet to the Introduction of a protective gas. A preferred means for introducing the protective gas is shown in FIG. 1 and FIG. 4 illustrates and consists of a gas line connected to a gas source, not shown 30, which has a distributor head 32 at the lower end. The distributor head 32 has, as in FIG 4 illustrates a central tube 34 having openings 42 for introducing argon into a space 33, that by means of an outer shell 36, an attached to this upper plate 38 and one the End closure of both the outer shell 36 and the lower plate 40 forming the central conduit 34 are limited is. The space 33 can substantially with a gas-permeable material, for example Steel wool, or a porous metallic material, can be filled around the emerging from the openings 42 Distribute argon even more evenly. The envelope 36 is also designed so that the gas is proportionate exits uniformly so that only minimal gas turbulence is caused in the mold will. A preferred embodiment of the sheath 36 is a correspondingly shaped cylinder made of wire mesh.

The header 32 and gas line 30 are, as shown in FIG. 1 illustrated, preferably from inserted into the mold at the top, with the distributor head sitting on the bottom of the mold or in whose immediate vicinity is arranged. To keep the introduced argon in the mold is A cover 44 is arranged over the opening. The cover 44 consists of an aluminum foil, which can be attached by means of a wire 46.

The method according to the invention comprises the following steps: The in F i g. 1 mold illustrated is first covered with an aluminum foil 44. The header 32 and the line 30 are then inserted through a hole in the aluminum foil to bring argon to the bottom of the casting mold to introduce.

In the method according to the invention, which preferably uses argon as protective gas, this is Argon is evenly distributed at the bottom of the mold and introduced with minimal turbulence so that move the argon vertically up through the mold and remove all air from the mold can push out. This method is particularly advantageous as there is only a very small mixture of air and argon in the mold takes place, a circumstance that gives rise to both high efficiency as well as profitability. For example, it has been found that practically all air Can be removed from the mold with only 1.25 times the volume of argon, if this, as described above, is introduced. This is in stark contrast to the 7 to 10 times the volume Protective gas that would normally be required to remove the air from an equivalent casting mold to displace a protective gas jet that is directed into the mold and an excessive

ίο causes turbulence and mixing of the gases.

Immediately, preferably no longer than 2 minutes, after the air has been removed from the mold the casting ladle 10 containing the molten metal is moved over the casting mold 14 filled with argon brought (Fig. 2), wherein the bottom outlet 12 is aligned with the upper opening of the mold. so argon is passed into the ring line 24 to remove practically all of the air from the pipe section 16 and the gap To displace 48 between the pipe section 16 and the cover. The argon flow is then at least 8 Maintained up to 10 seconds before the pouring stream 19 by removing a corresponding stopper is released.

The pouring ladle 10 is in a suitable pouring position when the lower edge of the pipe section 16, as indicated at 48, is a few centimeters away from the cover. Preferably a certain Gap 48 is maintained so that gas displaced by the entry of molten metal to the atmosphere can escape. This escaping gas consists not only of argon, but also a small amount Scope of gases emanating from the metal. It was found to help prevent of infiltration of unwanted gases back into the argon-filled casting mold during casting the exit velocity of the gas passing through the gap 48 must be at least 7.6 cm / sec got to. Where, of course, the prevailing conditions in the vicinity of the casting point, for example strong winds to prevent proper gas flow out of the mold, it is necessary to to increase the gas flow out of the line 24 out.

Another embodiment of a device for carrying out the new method is shown in FIG. 6th illustrated. In this case, the mold is provided with a removable hood that is flat Has plate 50 with a central opening 51. A loop 54 provided on top of the plate is provided with a gas inlet 52 for connection to a source of argon; a plurality of openings 53 in the ring line are directed inwards towards the center point of the line. The line 54 can be detachably or permanently attached to the plate 50, depending on the special requirements.

Optionally, the pipe section 16 can also be arranged on the flat plate 50. In this case there should be a slight gap between the bottom of the plate 50 and the pipe length during casting of the block are maintained.

The casting process in this device is essentially the same as in the previous case in Use of a cover 44, except that after cleaning the mold 14 with argon the plate 50 and the line 54 are applied to the mold instead of the cover 44, only the opening 51 being left free. The pouring then takes place through the bottom outlet 12 immediately above line 52, preferably in

Contact with this, is arranged and then a flow of argon is introduced out of the line 54, to fill the space between the plate 50 and the bottom of the ladle and the argon flows also to let hit the pouring stream. It should be noted that the use of the removable plate 50 is limited to smaller block shapes that are less than about 101 in size. For For larger shapes, the aluminum foil cover is preferred as this is subject to the action of the High temperatures of the metal in the casting mold during and after casting are less likely to warp.

Claims (4)

Patent claims: 1. Method of pouring metal from a ladle into a casting mold under falling Exclusion of the effect of the atmosphere on the metal by protective gas, characterized in that that the mold is filled with protective gas, which is displaced by the incoming pouring stream and envelops it, as well the pouring level covers, at the same time the pouring stream below the bottom outlet of the pouring ladle is enveloped by a further protective gas stream directed at it and both protective gas streams combine to form a protective gas jacket that envelops the beam over its entire length. 2. The method according to claim 1, characterized in that the pouring stream at his Exit from the bottom outlet of the ladle enveloping inert gas stream is directed downwards and with the upwardly directed flow of the protective gas displaced from the mold above the mold hits. 3. Device for performing the method according to claims 1 and 2, characterized through a nozzle ring (24) arranged on the underside of the pouring ladle (10) and a nozzle ring Pipe section (16) surrounding the nozzle ring and extending parallel to the pouring stream for guidance of the upper shielding gas flow. 4. Apparatus according to claim 3, characterized in that the casting mold with a top Cover (44) is closed, which has an opening for introducing a with a distributor head (32) provided gas line (30). Considered publications:
German Patent No. 1,111,781;
French patents No. 1168 680,
658;
British Patent No. 781 277. 1 sheet of drawings 409 537/420 2.64 © Bundesdruckerei Berlin