US2131307A - Chill for continuous string casting - Google Patents

Description

Sept. 27, 1938. v G. BEHRENDT CHILLYFOR CONTINUOUS STRING CASTING Filed Nov. V12, 195e Patented Sept. 2 7, 1938 UNITED STATES PATENT OFFICE) allais cmu. ron. coN'rlNUoUs arma cAs'rlNG Ger-ima Behrendt, Denim-mr, Germany .Appueeaen November 12,1936, serl'n Ne. 110,538 In Germany October 25, 1935. p

The present invention relates .to casting moldsand more particularly pertains to. the longitudinal shape of a chill adapted i'or continuous` stringcasting of steel.

5 It is known to cast metals in acontinuous string. For carrying out this process it has been proposed to cast the metal in a hottomless mold. allow it tocongeal therein and continually and uniformly remove it fromthe mold according to l0 the progress of the congealing. The casting molds generally employed forshaping the string have a prismatic -or cylindrical internal shape...

Various suggestions have, however. been made to .give the casting mold a shape widening in. 1.5 cross-sectional area towards its outlet end. Such molds add to instead of avoiding the chfjections hereinafter set forth, inherent to the continuous string casting process in that, especially when castingmetals withl a high melting 'point such as steel, the diiiiculty arises that the quantity of heat accumulated in th'e material to be cast cannot be conducted oi!V suiliciently quickly, so that the economy'and practical carrying cut of the string-casting is ieopardised,

25 The lliiid meta'l 'comes' into contact with the *cold mold wall in the string'casting chill. and becomes coated with a thin skin of congealed As the conducting oi! of'theheat progressesthisskinincreasesinthickneasincon- 30 tact with the cold mold,wall until it can wi wallsothatagapisproduced. .Thewayinwhich 36 the heatis conducted di'. therefore. varies-in such a `manner that the leading ci! ci the heat by conduction predominating at 'changes into a leading oi! chieily cilectcd by lladiation. During the continuous and also d0 rupted discharging ot the Matting from 'chill mold inthe string casting chills employed, an air, gap is formed which larger towards the delivering side t the string o! theheat. l Thisisincontradictiontotherequiremenhto withdraw from theingct at leasttheaamequantitles of heat after as beiore theshrinkage comz-menceabecauseitmayotherwisehappenthat V the core, which is still liquid. reheats'the ingot skln,sottensitandthmcausesitto-bmst under.

the pressure of the liquid metal. Thus, it has been noticed, particularly in the case of steel ingots of large diameter, which during the shrink- 38e lnove away much farther from the mold wall than those ot small diameter, that the dan- 5 ger of the forming of longitudinal cracks is much greater `than in the case of thin ingots." This is primarily due to the reduced withdrawal of heat set forth' above and the results therefrom.

.` .According to the invention the objections to l0 casting molds hitherto used forstring cast A ing are 'eliminated or at least considerably reduced by a special shape of the casting chill. The shape of the casting chill accordingto the invention is characterized in that the internal l5v cross-sectional -area oi the string mold narrows along vthe 'portion on which the string contracts during the congealing process. so that the formation vci' an air gap between the wall of the chill and the cast stringis as faras possible pre- 20 vented. and, on the other hand, the extent o! the narrowing does not exceed that of the shrink- Consequently. the internal cross-sectional areaof-theingot mold decreases eithenalong the y entire. lengthh or only along a portionthereoi 2 5 towards the discharge end.

The drawing shows a vertical cross-section of.

vthe mold.

.wana meld conm-wea in this mannertne vmovingstringwill always remain as near as l0 possibleto thecold mold wall. Thus, the cooling conditions prevailing in the.. chargingend of' .the mold do not change at all or only slightly,

so that-the danger of formation of cracks is eliminated. Furthermore it is more easily pos- $5' v `siixole to. cause large quantities of metal to congeai .in a short time.

. 'I claim:-

GERHARD

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