US1819364A - Hot top - Google Patents

Description

"swan-WWW". 7

Patented Aug. 18, 1931 UNITED STATES PATENT OFFICE LEELiQE -A IQJ BTE, or rrrrsnunen, AND EIJ IER B. WELCH, or McKEESPOBT,

PENNSYLVANIA, AssIeNons T FIRTH-STERLING STEEL COMPANY, or IIcxEEsroar, PENNSYLVANIA, A conronA'rIoN or PENNSYLVANIA HOT TOP Io Drawing.

This invention relates generally to hot grips commonly used in pouring steel ingots. ot tops are refractory forms placed on the top of the ingots and into which the metal is poured in order to maintain the top portion of the ingot in a molten condition so as to prevent or decrease the formation of shrlnks and pipes in the ingot.

Up to the present time, these hot tops have 10 been made 0 clay or other similar refractory material. Clay hot tops do, to a certain extent, decrease the amount of shrinks and pipes in an ingot, but they are not of sufiiciently good insulating characteristics to prove satisfactory in some cases where itis desired to substantially eliminate entirely any shrinks or pipes in the ingot. Furthermore, clay hot tops are relatively expensive. In using clay hot tops it is necessary to heat go them before applying them to the ingot molds. Even when the hot tops are heated before placing them on the ingot molds, they sometimes cool to such an extent before the I metal is poured into the mold that shrinks or pipes form.

In accordance with our invention, we provide hot tops which have a much greater insulating value than those heretofore employed. Accordingly, it is not necessary to 30 preheat our hot tops before applying them to the mold. They have an insulating value sufiiciently great so as to materially decrease the amount of shrinks and pipes that would ordinarily be formed in an ingot, and are 5 mainly composed of material which is much cheaper than cla We take a car onaceous material or mixture of carbonaceous materials, such assay jggt, wood shavins, charcoal, coke, u 1 le q! ,SllCh as corn ggbs, corn stalks, sfil ayy, or m, and

mix this with JET ctor inder. The mixture is then formed into t e desired shape and dried.

If desired, instead of using the carbonaceous material and the binder alone, we can first coat the carbonaceous material with a I n such, for example, as sodium chloride, sodium tungstate, or

This may be accomplished by immersing the Application filed September 24, 1929. Serial No. 394,920.

sawdust or other carbonaceous material in a solution of the fire-proofing salt, and thereafter evaporating the water. This deposits a coating of a fire-proofing salt on the particles of the sawdust. The saw .isthen mixed with a biggie refera y a silica suc imhi n ilicate or potassium s1 icate, and the mixture is then pressed into the desired shape. The article so formed is dried in order to eliminate any excess water which, on if present, might tend to cause the hot top to disintegrate when subjected to heat.

After the hot top has been dried it preferably is coated with a coating of a silicate cement, such for example, as sodium silicate. .5 This coating may be accomplished by dilpping the article or by painting it with t e coating material or by any other desired method. The coating prevents the article from absorbing moisture and also tends to 7 more firml bind together any loose particles which mig t have resulted from the forming operation and prevents these loose particles from burning out when the hot top is used.

As a specific example of the manner of carrying out our invention, sawdust is first dried and then immersed in a solution of sodium chloride. It is then heated to drive 011' the water and deposit a layer of sodium chloride on the particles which acts as a firea0 proofing medium. The dried coated particles are then mixed with sodium silicate in such proportion as to cause the particles to adhere to each other when they are pressed to shape. In practice we have found 6 a b volume of oium toa ut ten arts lume of sawdust makes the mixture of a consistency which can be satis- 1 ma mamas,

ac ory cement, with the saw V fifoofzid s aw dhst and binder In order to prevent the hot top from smouldering too greatly. The proportions of sawdust to clay or other refractory material may "be varied to suit the conditions. We prefer to employ not less thanpercentsawdust Tani not'morg than iiftyp ercent clay. H For many'ffifrfioses a mixture a'fioiit'eighty percent sawdust and, percent cla has proved very satisfactory. If cla or t er, refractory material is mixed wit the sawdust, a fire-proofing material such as sodium 5 chloride, sodium tungstate, or alum, may or may not be used.

In the description we have referred to sawdust as being a carbonaceous material suitable for making hot tops. It is to be 0 understood, however, that other carbonaceous materials having similar properties may be used in place of sawdust.

Aside from the fact that hot tops may be made very cheaply according to our invention, our hot tops retain the heat much better than those now in use and, accordingly, decrease the amount of shrinks and pipes ordinarily present in ingots. We have referred specifically to the pouring of steel ingots,

but it should be understood that the hot tops may be used in pouring other metals.

We have described several preferred compositions and methods by which our invention may be carried out, but it should be understood that the invention may be otherwise embodied or practiced within the scope of the following claims.

We claim:

1. A hot top comprising carbonaceous material, said carbonaceous material being impregnated with a fire-proofing material, and a binder.

2. A hot top comprising carbonaceous material, said carbonaceous material being impregnated with a fire-proofing material, a refractory, and a binder.

3. A hot top comprising carbonaceous material, a fire-proofing salt, and a silicate o binder.

4. A hot top comprising carbonaceous matg ial, sgdium chloride, and s o diumsilicate.

5. A hot top comprising carbonaceous ma- 6: terial, sodium chloride, clay, and sodium sili- "cafe.

our hands.

L. GERALD FIRTH. ELMER B. WELCH.