US2841843A

US2841843A - Hot top

Info

Publication number: US2841843A
Application number: US508685A
Authority: US
Inventors: Nouveau Henri
Original assignee: R L DOITTAU PRODUITS METALLURG
Current assignee: R L DOITTAU PRODUITS METALLURG; S A R L Doittau Produits Metallurgie
Priority date: 1954-10-21
Filing date: 1955-05-16
Publication date: 1958-07-08
Anticipated expiration: 1975-07-08

Description

H. NOUVEAU July 8, 1958 HOT TOP 2 Sheets-Sheet 1 Filed May 16, 1955 H. NOUVEAU July 8, 19.58

I-IOT TOP 2 Sheets-Sheet 2 Filed May 16, 1955 mwa/M 9 1 l /4 5\ Lm @Il 1 .Q 5 3 7 9 G/Nl x 1 WH 1. v 1M 5 United States Patent O HOT TOP Henri Nouveau, Saint-Germain-les-Corbeil, France, assignor to S. A. R. L. Doittau Produits Metallurgie, Les Tarterets-Corbeil, France, a corporation of France Application May 16, 1955, Serial No. 508,685 Claims priority, application France October 21, 1954 3 Claims. (Cl. 2Z-147) This invention relates to the casting of cast parts.

It is known that in the production of cast metal parts, more particularly in the casting of metal ingots, it is necessary to maintain the head of an ingot or feed-head in a molten condition so that the molten metal will feed the body of the part or ingot proportionally as the said body solidies and shrinks.

In order thus to prolong the liquid condition in the ingot head or feed-head, use is made of insulating refractory lining or of exothermic linings, or of linings having insulating and/or refractory portions and exothermic portions.

My co-pending application serial No. 508,658 tiled May 16, 1955, now Patent No. 2,821,000, granted, January 28, 1958, describes a method of using exothermic materials wherein the exothetmic material is used in the form of a lining for the wall of the feed-head frame or the ingot mold in such a manner as to bring the lining into contact with the molten metal constituting the feed-head, a layer of insulating material being interposed between the exothermic lining and the Wall of the ingot or other mold.

Now, in the methods of using exothermic materials, it is only necessary for the combustion to begin at the instant when the metal constituting the feed-head tends to solidify, and for it to continue until the moment when the metal in the ingot mold has completely solidified and there is therefore no longer any need to add liquid metal from the feed-head. Moreover, the heat supplied should be sucient to keep the metal in the feed-head in a molten condition.

It is known that it is possible to calculate mathematically the weight of exothermic material required for heating the feed-head so as to ensure a uniform feed of metal to the part or ingot, i. e. to satisfy the latter condition. Each exothermic material has in fact a specific useful caloriiic value, but independently of the caloric value the exothermic material must have particular characteristics according to the case in question, these characteristics being reactivity, that is to say: the time at the end of which the combustion of the exothermic material begins, and the duration of combustion.

In exothermic materials, the longer the starting delay of the reaction, i. e. the weaker the reactivity, the longer is the duration of the combustion of the material and the lower is the quantity of heat which a given mass of the said material is capable of liberating. Therefore, with the former methods, since the supply of heat and the duration of the combustion period were given, it followed almost of necessity that combustion started well before the instant when it would have been useful and/or ended after the useful period.

It has therefore seemed indispensable to make the reactivity, i. e. the time at the end of which the combustion starts under the action of the heat evolved by the molten metal, on the one hand, and the caloriiic value of the exothermic material and the duration of combustion,`

on the other hand, independent of one another. This il-Ce result is achieved by the method according to the present invention.

The present invention provides a method of using tion of the exotherrnic material will commence is there-` Afore a `function of the nature, and more especially of the co-eicient of heat conductivity, of the inert material and` of the thickness of the layer of said material. Therefore this periodcan in this manner be made independent of the properties of the exothermic material itself.

The layer of inert material is preferably constituted by agglomerated or non-agglomerated molding sand or by a material used in foundry work for the construction of molds. This material can contain certain substances capable of varying its heat conductivity. The method according to the invention `is preferably combined with the method described in the aforo-mentioned co-pending application, and in the case a triple-effect lining will be constructed, comprising in succession from the Wall of the ingot mold towards the inside, a layer of insulating material, a layer of exothermic material, and a layer of inertV material, which is preferably identical with the insulating materiaL Combination of the two methods also makes possible a limitation of the height of the exothermic material to the zone comprised between the maximum upper level and the maximum lower level of the metal in the head of the ingot mold. In fact it has been found that with this 'rial in the upper portion which the metal has left as Consequently and according soon as theingot solidities. to the invention, the layer of exothermic material preferably increases in thickness from the maximum upper level of the molten metal to the maximum lower level of the 'metal after solidification of the ingot.

The present invention also includes as novel industrial products pre-fabricated slabs for the construction of 1inings for ingot molds and feed-head frame, the said slabs i comprising a layer of exothermic material embedded in a mass of an inert material and preferably of an insulating material of the molding sand type. It also includes such slabs wherein the layer of exothrermic materials is limited to part of the height of the slab, and wherein the thickness of the layer of exothermic material increases from the top towards the bottom of the slab.

Various constructional examples of slabs for carrying into effect the method according to the invention will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a sectional view of a feed-head frame with its lining in accordance with a first embodiment.

Fig. 2 is a corresponding sectional view of a second embodiment. t

Fig. 3 is a half-sectional View taken through line III- `IIIjof Fig. 4 of the feed-head frame with its lining according' to a third embodiment.

t Fig. 4 is a quarter view section, taken on the line IV- IV of Fig. 3.

Fig. is a View corresponding to Fig. 3 of a fourth embodiment, and i Fig. 6 is a section of aningot mold ofa special type for carrying into effect Athe method accordingto theV invention. v t

' In the embodiments illustrated in Figs. 1 to 5, the feed-head' frame 1 is mounted on an ingot mold 2; the feed-head frame is of square cross-section and in the form of a truncated pyramid.

The feed-head frame 1 bears against the upper edge of the ingot mold 2 with a base portion 3 which, in Figs. 1V and 5, extends from ve to ten millimetres inwards so as to form a continuous band 4 projecting round the base portion. Bands 5 having, with respect to the inner face of the feed-head frame, the same excess thickness as the band 4, and extending perpendicularly to said band 4, are formed on the internal faces of the feed-head frame. The edge ofthe latter is formed with an inwardly projecting rim 6 which limits the useful opening of the feed-head frame.

The method according to the invention is carried into effect by the use of a lining formed of four trapezoidal slabs. In Fig. 1 the slabs are formed of a layer of insulating material 7 facing the interior of the ingot mould and` lined at theV feed-head frame side with a layer of exothermic material 8. The exothermic material can be applied directly against the wall of the feed-head frame but in order to prevent excessive heat loss it is preferable to form, between the exothermic material and the wall, an air gap 9 which acts as a heat-insulation means and is delimited by the projecting

bands

4 and 5.

The embodiment shown in Fig. 2 is similar to that of Fig. l but the layer of exothermic material is limited to the height of the lining comprised between the upper level 10 of the metal when the ingot is poured and the lower level 11 of the metal after solidication.

In Fig. 3, the slabs are formed by a means of an insulating material 12 wherein is embedded, throughout part of the height of the slab, a layer of exothermic material 13. This layer of exothermic material is thus bounded towards the interior by a layer of insulating material 14 and on the frame side by a layer of insulating material 15 wherein are formed orifices 16 for facilitating the evacuation of the combustion gases. As in the preceding embodiments, the lateral edges of the slabs are bevelled at 45 so as to permit of their assembly in the frame, and they are fashioned so as to form a pronounced curve at the point of junction between two slabs. The lower edge 17 is likewise bevelled.

Inl the embodiment according to Fig. 4, the layer of exothermic material is of constant thickness throughout its entire height. In the embodiment shown in Fig. 5, the thickness of the layer 13a of the exothermic material increases from the upper portion towards the bottom portion of said layer which, in sectional view, is of trapezoidal cross-section. In a similar manner to that described with reference to Fig. 2, the upper part of the layer is disposed slightly above the upper level 10 of the metal in the feed-headframe at the conclusion of the pouring of the ingot, and the bottom part is slightly below the lower level 11 of the metal after solidiication thereof.

The insulating material constituting the slab is preferably agglomerated molding sand. The metal is therefore in contact either with the metal of the ingot mold or with a layer of molding sand. The appearance of the surface of the ingot produced will be everywhere satisfactory from the technical point of View.

Consequently, I have been led to adopt as an ingot mold a special form wherein the feed-head frame is in fact dispensed with. One embodiment of such a mold is shown in Fig. 6. The ingot mold 18 is of truncated pyramidal form as usual, and inn its upper portion it has an offset part 19. In this offset part is disposed a lining according to the invention, formed of a thickness of insulating material 20, preferably of agglomerated molding sand, wherein is enclosed a layer of exothermic material 21, the said layer of exothermic material being limited in height to the part comprised between the maximum upper level 22 of the molten metal at the time of filling the ingot mold and the maximum lower level 23 reached after solidication of the ingot.

It will be clear that although the embodiments de' scribed hereinbefore relate more especially to the casting of ingots, the invention is also applicable, and under the same conditions, to the production of other cast parts.

What I claim is:

1. In a feed head metal casing for an ingot mold which casing is provided with an inner lining comprising a layer of aggolomerated exothermic material and a layer of inert material that is exposed to molten metal of a feed head, the said metallic feed head casing having an inwardly projecting lower rim and inwardly projecting, spaced narrow ribs extending upwardly from said rim, said rim and ribs having cemented on the inwardly di" rected surface thereof the external face of preformed blocks comprising a layer of agglomerated exothermic material and an internal layer of agglomerated moulding sand so as to delay ignition of the exothermic material by the heat of the poured molten metal.

2. In a feed head metal casing for van ingot mold which casing is provided with an inner lining comprising a layer of exothermic material between two layers of insulating material of which one layer is exposed to molten metal of a feed head, the said metallic feed headcasing having an inwardly projecting lower rim and inwardly projecting, spaced narrow ribs extending upwardly from said rim, said rim and ribs having cemented on the inwardly directed surface thereof, the external face of preformed blocks comprising a layer of agglomerated material forming a gas pervious insulating layer, a layer of agglomerated exothermic material and an internal insulating layer of agglomerated moulding sand so as to.

delay ignition of the exothermic material by the heat of the pouredmolten metal and to prevent as far as possible transmission of the heat from the exothermic material to the metallic feed head casing.

3. In a feed head metal casing for an ingot mold which casing is provided with an inner lining comprising a layer of exothermic material between two layers of insulating material of which one layer is exposed to molten metall of a feed head, the said metallic feed head casing having an inwardly projecting lower rim and inwardly projecting, spaced narrow ribs extending upwardly from said rim, said rim and ribs having cemented on the inwardly directed surface thereof the external face of preformed blocks comprising a block 0f agglomerated insulating material with, embedded therein on a partA of their height and a part of their thickness, a layer of exothermic material so as to delay ignition of the exothermic material by the heat of the poured molten metal and to prevent as far as possible transmission of the heat from the exothermic material to the metallic feed head casing.`

References Cited in the file of this patent UNITED STATES PATENTS 1,717,575 Messler June 18, 1929 1,804,207 Charman et al. May 5, 1931 2,390,500 Charman et al. Dec. ll, 1945 2,490,327 Soiel Dec. 6, 1949 2,678,481 Peterson May 18,1954

FOREIGN PATENTS 524,383, Great Britain Aug. 6, 1940 142,209 Sweden Sept. 22,1953,