US2063377A - Way of manufacturing fireproof nozzles for ladles - Google Patents

Description

Patented Dec. 8, 1936 UNITED STATES WAY OF MANUFACTURING FIREPROOF NOZZLES FOR LADLES Govert Helmer, Surahammar, Sweden, assignor to Allmtinna Svenska Elektriska Aktiebolaget, Vasteras, Sweden, a corporation of Sweden Application March 22, 1935, Serial N0.-12,436

' In Sweden March 23, 1934 1 Claim.

When pouring steel or other metals out of ladles, nozzles are used of fire proof material generally consisting of fire clay. This material is, however, to a high degree subjected to erosion 5 by certain steel qualities, particularly such one having a high percentage of manganese and soft rimming steel, whereby the bore hole of the nozzle increases in diameter often to more than twice the original value and also is unevenly eroded so that the tightening'between the seat of the hole and the stopper is uncomplete. Moreover, the fire clay has a tendency at a high temperature to stick to the stopper and make further pouring impossible.

In order to avoid these inconveniences, the bore of the nozzle has been provided with a lining of magnesite, which is both wear resisting and able to withstand the molten metal. The magnesite is burnt at a temperature of about 1550 C., which is considerably higher than the burning temperature of fire clay. The lining is therefore made as loose rings which are placed in a corresponding cavity in the fire clay nozzle. On account of the way of manufacture and the high burning temperature, this lining will be several times more expensive than the fire clay piece proper and when the lining ust as the nozzle only can be used a single t e, the yearly cost will be rather considerable. Another inconvenience is that the magnesite lining manufactured in this way in many cases is too wear resisting. Particularly at soft rimming steels it is of importance that the steel is poured at a certain temperature at a certain constant rising speed in the mould. This 35 cannot be efiected without a certain wear of the lining which,.however, must not be so large as with fire clay only, but the diameter of the pouring hole must increase in the same way as the metal, 1. e. the pressure height, is reduced in the.

ladle.

are avoided by not burning in the ordinaryway.

the magnesite lining to sintering before use. The

present invention is based hereupon. According 5 to the invention the bore hole in the fire clay piece is lined with a lining of magnesite or other wear resisting material, such as magnesium oxide, chromium oxide, aluminium oxide or oxidesof other earthy metals which are mixed in known way in powder form with binding substances and if required also with other additional substances. These other additional substances have for their object to reduce the fusing point of the mixture in order to obtain a certain wear required for a certain case. For this purpose quartz, fluor-spar, alkalies and the like may be used. The lining material is heated at temperatures considerably lower than the normal burning temperature of magnesite, which is about 1550 C. so that it ohtains so great mechanical strength that the surface of the lining which is exposed to wear afterwards at pouring can be burnt to sintering .by the heat of the metal flowing through the bore hole. When the lining of the nozzle is made on the working spot, the quantity of the substances of the lining material may easily be adapted to suit the metal quality, which is moulded at a time so that after heating the increase of the hole diameter by wear at the pouring of the metal substantially compensates the reduced pressure height of the metal in the ladle, whereby about constant pouring speed is obtained during the whole time of pouring. As an example may be stated that when pouring rimming material with 0.05% C the desired wear has been obtained when pouring about tons of metal at a mixture of 85% magnesite and 15% binding substances. At the same materialquality but with 0.10% C it has proved suitable to use 75% magnesite and 25% binding substances. v

The attached drawing shows a form of arrangement of a nozzle with magnesite lining in vertical section. The fire clay piece is marked I and the hole of the nozzle 2. The upper part is lined with magnesite 3. The hole'can also be entirely lined with magnesite, but this is less suitable as the poured metal in this case sticks to and forms shanks round the lower'edge of the magnesite on account of the good heat conducting qualities of this material. The magnesite can be rammed in known way into the fire clay nozzle or formed as a loose sleeve. In order to obtain.

suflicient mechanical strength the magnesite mixture need only be heated at about 200 C. or even only dried against a hot furnace wall. The magnesite lining can also be made at the same time as the me clay nozzle and is heated at the same time as this at the same temperature, which fire clay requires for its burning. Due to this also this way of manufacture will be very economical as any special arrangements of burning the magnesite are not required.

I claim as my invention:

A method of producing a. fireproof nozzle for a metal-pouring ladle which comprises apply ng to the pouring hole of the fire-clay body of'the nozzle a wear-resisting lining material such as magnesite in an unburned condition, heating the lining material to a temperature substantially lower than its burning temperature and subse-.

quently burning the wearing surface of-the lining material to sintering by contactwith the metal flowing through the nozzl GOVERT HEIJER.

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