US2509618A - Bottom-casting ingots in molds - Google Patents

Description

y 1950 B. M. TIGERSCHIOLD 2,509,618

BOTTOM-CASTING mco'rs IN Moms Filed Feb. 28. 194? Fi -1 T'TZ.

'/ r? fl- Patented May 30, 1950 UNITED STATES PATENT OFFICE BOTTOM-CASTING INGOTS IN MOLDS Bo Magnus Tigerschiiild, Degerfors, Sweden Application February 28, 1947, Serial No. 731,617

In Sweden May 29, 1946 The present invention relates to the manufac- 1 Claim. (Cl. 22-200) ture of ingots of iron or steel or other metals or alloys in moulds while utilizing the so called bottom-casting method (that is to say introducing the molten metal from beneath into themould') The object of the invention is to eliminate or at any rate materially reduce many of the disadvantages of the present methods of bottomcasting of ingots in moulds according to methods hitherto used.

In the bottom-casting of, say, ingots of killed steel it is common practice to use moulds provided with hot tops (1. e. shrink head casings) except in such cases where a certain degree of nonhomogeneous structure may be allowed. This is due to the fact that ingots of killed steel manufactured by bottom-casting in moulds having no hot tops always have a more or less pronounced pipe formation. Various methods have been proposed in order to-reduce the degree of such pipe formation. The said methods, as a rule, aim at effecting a rapid solidifying of the surface of the ingot so that more liquid steel under a comparatively high pressure may be introduced into the mould. The rapid solidifying of the surface of the metal may be obtained by pouring water on top of the ingot. These methods, however, require a high degree of attention to be paid by the operators and are, in fact, not very reliable, because of the fact that the pipe, which is nevertheless formed, is usually covered with an oxide film which renders difiicult the welding together of the metal surrounding the pipe.

In case of bottom-casting of rimming steel in a mould the latter, as a rule, is completely open at its top. In this case there is a great tendency for the structure of the ingot being of such a nature that sheet metal, and more particularly thin sheet metal, manufactured by rolling the ingot becomes more or less impaired by blisters. Owing to the lively spark formation during the casting of rimming steel ingots in a normal way the inner walls of the mould will be rapidly covered by iron oxide which must be removed at intervals, as for instance, by means of steel brushes, in order that the ingot surface shall be satisfactory. By applying the invention the formation of iron oxide film will be reduced to such a low degree that it is hardly noticeable. It is a 2 f usual practice in casting-ingots of rimming steel to cover the ingot by a lid, usually of cast iron after the casting is completed. Such a lid always represents a complication, and moreover it often becomes surrounded by molten steel and is then difficult to remove. The difllculties above stated as met with in eflecting the bottom-casting of rimming steel ingots may be eliminated to a certain degree by the use of so called bottle-neck moulds. Such moulds, however, must all be completely closed simultaneously by plugs immediately after the casting is completed which operation is so diflicult that the method has no extensive industrial use.

In the normal bottom-casting of rimming steel as well as killed steel with the use of open-topped moulds without feeder heads the ingots have a rather uneven top surface. The yield in the rolling operation therefore is considerably less than it would be if the ingot had a smoother and, pref erably convex shaped, top. Also the fact that it is impossible to cast all ingots from one heat to exactly the same length reduces the yield; nor is it possible, if desired, to bottom-cast ingots of various length on one and the same casting plate. The lastmentioned difliculties may be reduced by the use of bottle-neck moulds. In such case, however, other difiiculties appear, as above stated.

The present invention eliminates or considerably reduces these difliculties by the use of a mould open at its bottom end while completely closed at its top end.

Such a mould may be used to advantage in the manufacture of ingots of killed steel (inasmuch as the pipe will be clean and free from oxide) which highly increases the yield in the rolling of the ingot.

Instead of using a mouldpermanently entirely closed at its top end one may, of course, use a mould which may be temporarily tightly closed at its top by means of a, plug which should be put in place either prior to or during the casting operation.

In the accompanying drawing two embodiments of moulds are shown for the use of carrying the method according to the invention into effect.

Fig. 1 is a vertical section and Fig. 2 is a top plan view of a mould.

The mould I shown in Figs. 1 and 2 is open at its bottom end for the introduction of'the molten metal and completely closed at its top end. The inside wall 2 of the mould is preferably tapered upwardly and rounded at its top. The solid top wall of the mould is provided with a pair of lifting straps 3.

Experiments have proved that in efiecting a bottom-casting operation with the use of an ingot mould according to the invention, a downward flow of gaseous medium must take place along the inner wall of the mould because some gaseous medium escapes at the open bottom end of the mould during the casting operation.

What I claim is: I

A method of bottom-casting ingots in moulds which are entirely closed at their tops and free of top vents comprising introducing molten metal into the bottom of such a mould, and causing the gaseous content to escape between the outside of the ingot being cast and the inside of the mould and finally to the atmosphere from the bottom of the mould.

BO MAGNUB nonascmow.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PA'I'E'NTS Number Name Date 107,766 Duriee Sept. 27, 1870 129,699 Wellman July 23, 1872 1,560,036 Brown Nov. 3, 1925 2,242,703 ,Gathmann May 20, 1941 2,379,616 Watson July 3, 1945 FOREIGN PATENTS Number Country Date 822 Great Britain of 1822 9,514 Great Britain of 1896

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