AU652480B2

AU652480B2 - Gas purging plug

Info

Publication number: AU652480B2
Application number: AU25346/92A
Authority: AU
Inventors: Erich Stuzik
Original assignee: Plibrico Co GmbH
Current assignee: Plibrico Co GmbH
Priority date: 1991-09-24
Filing date: 1992-09-25
Publication date: 1994-08-25
Anticipated expiration: 2012-09-25
Also published as: GB2259974B; ATA189492A; FR2681611B1; DE4131756A1; AU2534692A; JPH0642882A; SE507717C2; SE9202747L; FR2681611A1; AT404257B; DE4131756C2; GB2259974A; GB9220073D0; SE9202747D0

Description

~n 2480

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION NAME OF APPLICANT(S): Plbrico GmbH ADDRESS FOR SERVICE: 6 o 9 enan Ka b o e ecoe o• an a D B a cog eDo o a a 09 S0 0 o a o L 6 0O DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street, Melbourne, 3000.

INVENTION TITLE: Gas purging plug The following statement is a full description of this invention, including the best method of performing it known to me/us:i LI -i-Q i 0 la The invention relates to a gas purging plug whose base is closed gas-tight by a metal bottom forming a gas distribution chamber and having a connection for gas supply and openings for at least S one electric temperature sensor which can be connected to an evaluating device and which extends through the gas distribution T t i: chamber into the gas purging plug and detects the temperature thereof to determine the wear on the material.

Due to its high thermal and mechanical loading by the melt, the surface of a gas purging plug inserted into a melting vessel is subjected to heavy wear. The removal of material caused by said wear leads to a decrease in the height of the gas purger. Due to this consumption, with increasing duration of use of the gas a a0e o a purging plug there is a risk that the melt may break through the worn block and emerge from the melting ladle. The gas purging plug must therefore be constantly monitored, so that it can be duly replaced if the purging cone fails to reach a minimum height.

German Paten. Specification 35 03 221 C2 discloses how the increased temperature of the gas purging plug accompanying its wear can be used as a reference value for assessing the 2 consumption of the block. To that end this citation discloses a gas purging plug into which two metal rods of different length are inserted which are enclosed by a ceramic envelope. At their lower ends the metal rods are connected to temperature sensors.

Their tips project beyond the ceramic envelopes and are in thermally conductive contact with the gas purger material, while the rest of the length of the rods is thermally insulated from the purger by the envelopes. This ensures that only the particular temperature at the tip of the rods is detected and passed on via the rods to the temperature sensors.

a. The device has the advantage of enabling the temperature of the a plug to be reliably measured and its degree of wear to be reliably assessed even with different melting temperatures in the melting vessel. However, the disadvantage of the prior art gas S purger is that the inclusion of the enveloped metal rods in the S plug causes increased manufacturing costs. Moreover, the prior art plug has the additional problem in practical operation that purging gas from the gas distribution chamber of the gas purging plugs emerges at the connecting places between the temperature sensors and the metal rods.

e o a.

ft is therefore Aobject of the invention to provide a gas purger which enables the measurement of the temperature of the gas purging plug to be reliably measured, while at the same time the gas distribution chamber is durably sealed in relation to the outside of the melting vessel.

-3- According to a first aspect of the present invention there is provided a gas purging plug whose base is closed gas-tight by a metal bottom thereby forming a gas distribution chamber between the metal bottom and the base and having a connection for gas supply and at least one opening for at least one electric temperature sensor which can. be connected to an evaluating device and which extends through the gas distribution chamber into the gas purging plug and detects the temperature thereof to determine the wear on the material of the gas purging plug, and wherein said at least one opening in the metal bottom is sealed gas-tight by a pot-shaped metal sleeve which is open in the direction of the outside of the metal bottom and engages in a depression in the base of the gas purging plug, said depression being thermally conductively connected to the gas purging plug and into each of which a temperature sensor is inserted which is thermally conductively connected to the metal sleeve.

The pot-shaped metal sleeve forms a gas-tight thermally conductive jacketing of the temperature sensor inserted in the sleeve. By welding, for example, the sleeve is connected gas-tight to the edge of the opening and extends through the gas distribution chamber into the depression in the gas purging plug, bearing via its top, closed portion against the material of the plug. When the plug becomes heated, the metal sleeve becomes heated in a similar manner and passes on its temperature to the temperature sensor. In this way the temperature of the gas purging plug can be readily determinf.d at any moment.

2 5 The depression in the lower face can be readily and cheaply produced during the manufacture of the gas purging plug. The depth of the depression can be very small, since all that must be ensured is the thermally conductive contact between the sleeve and the material of the plug. This feature also ensures that if the plug is cracked in an unforseen manner, the depression and sleeve do not form any additional channel for the emerging melt.

9 1 o •00 94O524p:\oper\kzya2534spe,3 -4- If the temperature sensor is to be reused after the gas purging plug has been interchanged, conveniently the temperature sensor is inserted releasably into the pot-shaped sleeve. This construction of the plug has the further advantage that a faulty temperature sensor can be replaced without the whole plug having to be interchanged. One possible way of inserting the temperature sensor releasably in the sleeve is characterized in that the pot-shaped sleeve has an internal screwthreading into which the temperature sensor can be screwed. Alternatively, the temperature sensor can be releasably attached in the pot-shaped sleeve by means of a cap-type connection or a clamping screw connection.

0 0 00 0 Satisfactory transmission of the temperature of the plug to the temperature sensor can be ensured by the feature that the S temperature sensor is rod-shaped and touches via its tip the inner end face of the pot-shaped sleeve. Conveniently the heat transfer from the plug to the sleeve is further boosted by the 00 ~feature that the pot-shaped sleeve is fitted into the depression o in the gas purging plug by means of a thermally conductive o mortar, more particularly SiC mortar.

A gas purging plug construction particularly well adapted to practical use is obtained if the temperature sensor is connected to the measuring device via a heat-protected connecting cable and a ceramic connector.

An embodiment of the invention will now be described in greater detail with reference to the drawings. wherein: U Fig. 1 is a longitudinal section through a gas purging plug, and Fig. 2 is an enlargement of the detail A in Fig. 1.

A gas purging plug 1 of gas-permeable material has a lower purging cone 2 and an upper purging cone 3. The side walls of the lower purging cone 2 are enclosed by a metal jacket 4 which at its lower end engages gas-tight around the metal bottom disposed at a small distance from the lower face la of the gas a "7 purging plug 1. A gas distribution chamber 6 thus formed between the metal bottom 5 and the lower face la of the gas purging plug 1 is connected via a gas supply line 7 to a gas pressure pipe (not shown).

i The lower face la of the gas purging plug 1 is formed with a depression 8. Opposite the depression 8 the metal bottom 5 has a circular opening 9. Welded gas-tight into the opening 9 is a pot-shaped sleeve 10 which engages via its upper closed portion 10a in the depression 8. The gaps between the outer walls of the portion 10a and the walls of the depression 8 are filled with thermally conductive SiC mortar 11. The sleeve 10 is formed with an internal screwthreading lo0b into which a rod-shaped temperature sensor 12 is screwed which via its tip 12a contacts the inner end face l0c of the pot-shaped sleeve 10. The temperature sensor 12 is connected via a thermally insulated cable 13 and a cable connector 14 to a temperature measuring device (not shown).

.4 Duringa he operation of the gas purging plug 1 the metal sleeve 1 ecomes heated in the same manner as the plug 1. The temperature development of the plug is continuously determined by means cf rhe -emoerature sensor 12 of :he measuring device and the measured temperature compared with a maximum temperature value, wnich is correlarea with the maximum permissible volume of wear. :f the remperarure of the gas purging plug exceeds this value, the ciua must ze erchanaed.

Throughout this specification and the, claims which follow, unless the context requires otherwise, the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

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Claims

1. A gas purging plug whose base is closed gas-tight by a metal bottom thereby forming a gas distribution chamber between the metal bottom and the base and having a connection for gas supply and at least one opening for at least one electric temperature sensor which can be connected to an evaluating device and which extends through the gas distribution chamber into the gas purging plug and detects the temperature thereof to determine the wear on the material of the gas purging plug, and wherein said at least one opening in the metal bottom is sealed gas-tight by a pot-shaped metal sleeve which is open in the direction of the outside of the metal bottom and engages in a depression in the base of the gas purging plug, said depression being thermally conductively connected to the gas purging plug and into each of which a temperature sensor is inserted which is thermally conductively connected to the metal sleeve.

2. A gas purging plug according to claim 1, characterized in that the temperature sensor is inserted releasably into the pot-shaped metal sleeve.

3. A gas purging plug according to claim 2, characterized in that the pot-shaped metal sleeve has an internal screwthreading into which the temperature sensor can be screwed.

004. A gas purging plug according to claim 2, characterized in that the pot-shaped 0 metal sleeve has a cap-type connection for the attachment of the temperature sensor. A gas purging plug according to claim 2, characterized in that the pot-shaped metal sleeve has a clamping screw connection for the attachment of the temperature sensors. 1. 00 90

6. A gas purging plug according to any one of claims i to 5, characterized in that the temperature sensor is rod-shaped and touches via its tip the inner enid face of the pot-shaped metal sleeve. 940526pAoperkkayX25346sVPc7 -8-

7. A gas purging plug according to any one of the preceding claims, characterized in that a thermally conductive mortar is inserted between the pot- shaped metal sleeve and the depression.

8. A gas purging plug according to claim 7 wherein the conductive mortar is SiC mortar.

9. A gas purging plug according to any one of the preceding claims, characterized in that the temperature sensor is connected to the measuring device via a heat-protected connecting cable and a ceramic connector. A gas purging plug substantially as hereinbefore described with reference to the drawings. 9 9 as,, a oaOO a. a a a a9 0 a 999 a 09 9 99 $4 9 9 DATED this 26th day of May 1994 20 Plibrico GmbH By Its Patent Attorneys DAVIES COLLISON CAVE

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