GB1581201A - Apparatus for shielding molten metal during teeming - Google Patents

Description

PATENT SPECIFICATION

( 11) 1 581 201 ( 21) Application No 18382/78 ( 22) Filed 9 May 1978 a 19) ( 44) Complete Specification Published 10 Dec 1980 4, l ( 51) INT CL 3 B 22 D 41/12 11/10 ( 52) Index at Acceptance B 3 F 11 K 11 P 2 B 11 P 2 C 11 P 2 X 13 A 3 K 1 A i D i Gi X 1 G 2 S 1 G 2 V 1 G 4 V 2 A 1 H 1 ( 72) Inventors: BRIAN POOLE PHILIP JOHN YOUNG ( 54) APPARATUS FOR SHIELDING MOLTEN METAL DURING TEEMING ( 71) We, AIR PRODUCTS AND CHEMICALS INC, a corporation duly organised and existing under the laws of the State of Delaware, United States of America, of P O Box 538, Allentown, Pennsylvania 18105, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and

by the following statement:-

This invention relates to an apparatus for shielding molten metal during teeming and to a carriage provided with such apparatus.

Figure 1 is a schematic perspective view of an installation for producing metal ingots.

The installation, which is generally identified by reference numeral 1, comprises a pit 2, which is typically 80 feet long, 12 feet wide and 12 feet deep A plurality of ingot moulds 3 to 10 are disposed in the pit 2 adjacent a plurality of pouring trumpets 11, 12 and 13.

A carriage 14 carrying a ladle 15 is arranged to move along the pit 2 The bottom of the ladle 15 is provided with a pouring outlet (not shown) In use, ladle 15 is filled with molten metal and is lowered into position on carriage 14 by a crane Carriage 14 is then moved along the pit until the pouring outlet is directly above one of the pouring trumpets.

A plug is then withdrawn upwardly from the pouring outlet and molten metal passes downwardly through the pouring trumpet and up inside the ingot moulds associated with the pouring trumpet The operation of pouring molten metal through the bottom of a ladle is known as teeming.

Typically, there is a gap of 10 to 12 inches between the bottom of the pouring outlet of the ladle 15 and the top of the pouring trumpet During teeming air comes into contact with the molten metal entering the trumpet and causes undesirable oxidation to occur.

It has been proposed to reduce oxidation by two methods In one method, the carriage 14 is dispensed with and the ladle 15 is lowered onto the pouring trumpet and held in position during teeming by an overhead crane This prevents the crane being used for other work during teeming In another method, a curtain or argon is formed around the molten metal stream by directing jets of argon downwardly from a toroidal nozzle supported around the pouring outlet.

Although effective, this method consumes a substantial quantity of argon.

It is an object of at least preferred embodiments of the present invention to provide an apparatus which, in conjunction with a shielding gas, will inhibit air entering the molten metal during teeming.

According to the present invention there is provided apparatus for shielding a stream of molten metal during teeming, which apparatus comprises a first arm pivotably mounted on a carriage capable of carrying a ladle; a second arm pivotably mounted on said carriage; a first cylinder open at both ends, connected to said first arm, and having one end which, during teeming, is urged against the pouring outlet on the bottom of a ladle mounted on said carriage; a second cylinder open at both ends, connected to said second arm, and moveable relative to said first cylinder to vary the distance between said first and second cylinders, and means to introduce a shielding gas into the interior of said cylinders, the arrangement being such that, in use, after the pouring outlet of a ladle is arranged over a pouring trumpet, said arms can be moved so that said first and second cylinders define a passageway between the pouring outlet on the ladle and the pouring trumpet into which shielding gas can be introduced via said means to inhibit air coming into contact with molten metal as it passes through said passageway.

Preferably, means are provided to bias said first cylinder, in use, against the pouring outlet on said ladle Such means many conrus A1,581,201 veniently comprise a counterweight mounted on said first arm.

Advantageously, said second cylinder is connected to said first cylinder by a flexible support Such support may conveniently be defined by chain linking which is preferably of relatively small mesh, e g 0 25 inches, and is arranged to prevent molten metal splashes from interfering with said cylinder movement.

Conveniently, a seal, for example an asbestos sleeve, can be mounted on the outside of said first and second cylinders to inhibit loss of shielding gas therebetween In this connection, for the avoidance of doubt, the term cylinder, as used herein, embraces bodies of all cross-sections, e g rectangular, square and polygonal, although bodies of circular cross-section are preferred.

In order to inhibit splashes of molten metal reducing the flow of shielding gas into the inside of the cylinders, the end of the first cylinder, remote from the second cylinder, may conveniently be provided with an inwardly extending lip which, with the inner surface of said first cylinder, defines a cavity opening towards said second cylinder, and wherein said means to introduce a shielding gas into the interior of said cylinders is arranged to introduce shielding gas into the interior of said cylinders via said cavity.

In order to inhibit damage to the pouring trumpets, means are preferably provided so that the carraige is rendered immobile when one or both the first and second cylinders are in such a position that movement of the carriage could result in the cylinder(s) damaging the pouring trumpet(s).

For a better understanding of the invention, reference will now be made, by way of example, to figures 2 and 3 of the accompanying drawings in which:Figure 2 is an end elevation of a carriage provided with apparatus in accordance with the present invention positioned for teeming; and Figure 3 is a section taken along line III III of Figure 2.

Referring to Figures 2 and 3, there is shown a carriage 20, which is mounted on rails 21, disposed to either side of a casting pit 52 The carriage 20 is provided with trunnions (not shown) which support a ladle 22 having a pouring outlet 23.

A horizontal shaft 24 is mounted fast on the carriage 20 and acts as a pivot for a first bifurcated arm 25 and a second bifurcated arm 26 A first cylinder 27 is mounted between the bifurcated ends of the first arm 25 and is biased against the pouring outlet 23 on the ladle 22 by counterweight 28 A second cylinder 29 is mounted between the bifurcated ends of the second arm 26 by means of pivotably mounted links, one of which is identified by reference numeral 30.

First arm 25 is provided with a first control arm 31 and second arm 26 is provided with a second control arm 32 As shown in Figure 3, an asbestos seal 33 is disposed around the outer surfaces of the first and second cylin 70 ders 27 and 29 respectively and inhibits argon escaping from inside the cylinders whilst permitting axial movement between the said cylinders.

In order to limit movement between the 75 first and second cylinders 27 and 29, a chain link shield 34 is secured to the bottom of the first cylinder 27 and the bottom of the second cylinder 29 As will be seen from Figure 3, the chain link shield 34 is funnel shaped and, 80 in use, inhibits molten metal entering the space generally identified by reference numeral 35.

The first cylinder 27 comprises a pair of coaxial walls 36 and 37 which define an annu 85 lar chamber 38 which communicates with an argon feed pipe 39 The annular chamber 38 is sealed by a bottom flange 40 and an upper flange 41 which supports an asbestos sealing ring 42 and includes a lip 43 which defines, 90 with the wall 37, a cavity 44 Forty 0 25 inch diameter holes 45 are bored through the wall 37 where shown and allow argon to flow from argon feed pipe 39 to the inside of the first and second cylinders 27 and 29 via the 95 annular chamber 38.

In use, carriage 20 is moved along rails 21 until the pouring outlet 23 on ladle 22 is directly above pouring trumpet 46 During this time counterweight 28 biases the seal 42 10 ( on first cylinder 27 against the bottom of the ladle 22 circumjacent the pouring outlet 23 and second cylinder 29 is held in a raised position by second control arm 32.

Once in position the operator raises con 10 ' trol arm 32 This immediately actuates a switch immobilising carriage 22 The second cylinder 29 moves downwardly until it rests on the top of the pouring trumpet 46.

Once in position argon is introduced 11 ( through argon feed pipe 39 and flows through pouring trumpet 46 and out of the ingot moulds thereby removing a substantial quantity of air from therein Teeming is then commenced and the flow of argon is con 11.

tinued until teeming is complete At the end of teeming the second cylinder 29 is raised to allow a sample of molten metal to be taken for analysis.

If the pouring outlet 23 becomes blocked, 12 ' first control arm 31 can be raised thereby lowering first cylinder 27 sufficient for the insertion of an oxygen lance.

Whilst argon is the preferred shielding gas it should be understood that other shielding 12 gases may also be used, for example, in certain cases, nitrogen may be acceptable.

Whilst the present invention is particularly intended for use in casting ingots, it is also applicable to continuous casting wherein the 13 ) j D 1,581,201 molten metal is teemed into a tundish.

Claims (8)

WHAT WE CLAIM IS:-

1 Apparatus for shielding molten metal during teeming, which apparatus comprises a first arm pivotably mounted on a carriage for carrying a ladle, a second arm pivotably mounted on said carriage, a first cylinder open at both ends, connected to said first arm and having one end which, during teeming, is urged against the pouring outlet on the bottom of a ladle mounted on said carriage, a second cylinder open at both ends, connected to said second arm, and moveable relative to said first cylinder to vary the distance between said first and second cylinders, and means to introduce a shielding gas into the interior of said cylinders, the arrangement being such that, in use, after the pouring outlet of a ladle is arranged over a pouring trumpet, said arms can be moved so that said first and second cylinders define a passageway between the pouring outlet on the ladle and the pouring trumpet into which shielding gas can be introduced via said means to inhibit air coming into contact with molten metal as it passes through said passageway.

2 An apparatus as claimed in Claim 1, comprising means to bias said first cylinder, in use, against the pouring outlet on said ladle.

3 An apparatus as claimed in Claim 1 or 2, wherein said second cylinder is connected to said first cylinder by a flexible support.

4 An apparatus as claimed in Claim 3, wherein said flexible support comprises chain linking which is arranged to prevent molten metal splashes from interfering with said cylinder movement.

5 An apparatus as claimed in any preceding claim, including a seal between said first and second cylinders to inhibit loss of shielding gas therebetween.

6 An apparatus as claimed in any preceding claim, wherein said first cylinder is provided with an inwardly extending lip which, with the inner surface of said first cylinder, defines a cavity opening towards said second cylinder, and wherein said means to introduce a shielding gas into the interior of said cylinders is arranged to introduce shielding gas into the interior of said cylinders via said cavity.

7 An apparatus for shielding molten metal during teeming substantially as hereinbefore described, with reference to and as shown in Figures 2 and 3 of the accompanying drawings.

8 An apparatus as claimed in any preceding claim, wherein means are provided to render said carriage immobile when one or both the first and second cylinders are in such a position that movement of the carriage could result in the cylinder(s) damaging the pouring trumpet(s) For the Applicants BRIAN LUCAS Chartered Patent Agent European Patent Attorney Printed for Her Majesty's Stationery Office, by Croydon Printing Company Limited, Croydon Surrey 1980.

Published by The Patent Office 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.