US2861305A - Ingot casting - Google Patents

Description

Nov. Z5, 1958 G. FENTON ETAL INGOT CASTING Filed Oct. 22, 1955 Lid/V ATTQQNEYS nited States Patent() 2,861,305 INGoT CASTING Geoffrey Fenton, Richmond, Sheiiield, and Reginald Mayorcas, Sheffield, England, assignors to The British Iron and Steel Research Association, London, England Application October 22, 1956, Serial No. 617,421 8 Claims. (Cl. 22-147) This invention 'relates to ingot casting and is particularly concerned with a novel form of feeder head for use in the casting of ingots. It is applicable to the casting of any high melting point metal or alloy and particularly to the casting of steel ingots which is taken as an example in the following. Feeder heads are usually made of rebrick and are designed to contain a reservoir of molten steel for compensating for the shrinkage in the steel in the ingot mould itself and thereby for reducing the formation of pipe and consequential unsound metal. Owing to the relatively large heat capacity of iirebrick, there are substantial heat losses from the steel in the head so that relatively large amounts of steel solidify on the surface of the head. The solidified steel is wasted as far as the casting is concerned; ideally, the head-,should be a perfect heat insulator so that there will be no solidiiication in the head and the volume of molten steel in the head need only be just sufficient to compensate for shrinkage in the mould.

According to the present invention, a feeder head comprises a tubular arrangement of good heat insulating material protected from the molten metal by a lining of refractory material. The refractory lining is capable of withstanding the'high temperatureconditions within the head while the heat-insulating material which normally is incapable of standing up to contact with the liquid steel prevents undue heat transfer from the steel and therefore a high rate of solidication. The volume of molten steel introduced into the head can therefore be smaller than in the case of iireclay heads.

In a convenient form of the invention, the heat insulating material is supported by a metallic tubular member having the refractory lining on the inner side. The refractory material protects the metal member which otherwise would melt owing-to the low heat transfer properties of the insulating material on the outside thereof. The head is designed to enable the refractory lining Vand the metal member itself to be easily replaced as they become damaged under the severe operating conditions. Thus the head may comprise an outer case of suitable tubular form having an inwardly directed plate at or near its lower end `and an upwardly directed lip on the inner edge of the plate and a removable lid on the upper end of the case. The tubular metal member is slipped into position behind the lip from the top of the case, the heat insulating material is located between the case and the metal member 'and the refractory lining is located on the lip; the whole is then secured by the attachment of the lid.

This construction gives a simple feeder head which is very easy to use in practice. For example, the refractory lining when it becomes unserviceable can be replaced with very little more trouble than the routine dressing of conventional rebrick heads; similarly any damage to the tubular metal member forming the inner wall of the container for the heat insulating material can be rectified merely by replacing it by a new member.

nessres of the lining and the inner wall should 'lie between 1A; inch and 3A inch and between 6 inch and Mi inch respectively according to the size of the ingot.

The heat insulating material may be vermiculite, slag wool or diatomaceous earth, and the refractory'material may Ibe gannister, compo lime gauged with Portland cement, reclay or insulating concrete.

The invention will be more readily understood lby way of example from the following description of one form of feeder'nead in accordance therewith, reference being made to the accompanying drawing which is a sectional i view through the head.

The head illustrated in the drawing is of truncated cone or pyramid shape and comprises a cast iron outer box 12 provided with an inwardly directed plate 13 on its lower edge. The plate 13 in turn has a small upturned lip 14 on its inner edge. A truncatedcone or pyramid shaped thin perforated sheet steel member 15 is dropped into the box`12 so that it is held on and located by the outer face of lip 14'. The space between the box 12 and the member 15 is then filled with a highly heat insulating material 16 and a layer 17of refractory material is cast on the `inner side of member 15 so as to rest on the lip 14,

the perforations assisting the keying of the refractory material to the member 15; instead of having the member 15 perforated,"'weldmetal studs may be placed on the inner Wall of member 15 for the same purpose. Finally a detachable lid 18 is placed over the assembly.V To enable the head tol be moved the case 12 is provided with handles 19.

The heat insulating material 16 may be any such material having a low bulk density and a low thermal c o'nductivity and it is preferred that the bulk density Vshouldl not exceed 8 lbs. per cubic foot and the thermal conductivity should not exceed 0.5 B. t. u./sq. ft./hr./in./ f1-.

Examples of suitable materials are vermiculite, slag Wool' I and diatoma-ceous earth.

The refractory material should be capable of protecting the heat insulating material from the heat of the cast ingot, but on the other hand should have a low .thermal capacity. The thickness of the layer 17 should therefore be kept as small as possible and preferably lies within the range 1A; inch to 3A; inch, depending on the size ofthe ingot. Suitable materials are gannister, compo, fireclay and insulating concrete. ln addition, the layer 17 may include exothermic material to prevent further the solidication of metal on the head. In this case, the layer 17 may be constituted by a single layer of exothermic material including refractory or by a layer of refractory between a layer of exothermic material and the steel member 15.

The thickness of the steel member 15 is also kept to a minimum and should lie within the range V16 in ch to 1A inch, depending on the ingot size.

The feeder head may be used either with or without a top addition, which if used reduces the heat loss through the top of the head. Preferably, immediately after teeming the ingot, a top addition of exothermic material and/ or insulating material is made.

The design of the head facilitates the replacement of the refractory layer 17 and the steel member 15 as these become damaged. In practice, it has been found that a 1A inch lining 17 of gannister lasts at least two heats and the member 15 with a thickness of 1/8 inch shows no sign of damage or deterioration after six heats. The vermiculite layer 16 requires infrequent replacement if at all. When using 1a iireclay head, the whole head must be changed once in about fifteen heats.

The construction described above enables a Substantially smaller volume of steel to be -used inthe head to ensure compensation for shrinkage and the increased cost of the head over known forms is more than outweighted by this reduction in metal.

We claim:

1. 'A feeder head'comprising a tubular container which includes a removable tubular metal inner wall, uncompacted heat insulating material located in saidI container, and a thin refractory lining of small heat capacity secured on and supported by the inside of said inner Wall to protect saidinner wall and said insulating material from temperature effects.

2. A feeder head comprising a tubular container which consists essentially in a tubular convergent metal outer,

wall, an annular metal base secured to said outer wall and projecting inwardly, and a tubular convergent metal inner wall removably supported on said base and spaced from said outer wall; a thin refractory lining ofsmall heat capacity, secured on and supported by the inside of said inner wall; and uncompacted heat insulating material substantially filling the space within said container between said outer wall and said removable inner wall.

3. A feeder head comprising a tubular container which consists essentially in a tubular convergent metal outer wall, an inwardly extending annular metal base integral with said outer wall and located at the bottom of said wall, an upwardly extending lip at the inner extremityv of said base and a tubular convergent removable metal inner wall supported on said base and retained by said lip on the outer side thereof; uncompacted heat insulating material substantially filling said container; and a thin re-` fractory lining of small heat capacity secured on and supported by the inside of said inner wall.

4. A feeder head comprising a tubular container which includes a replaceable tubular metal inner wall, uncompacted heat insulating material substantially filling said container, and a thin refractory lining of small heat capacity secured on and supported by the inside of said inner wall.

5. A feeder head comprising a tubular container which includes a removable tubular metal inner Wall, ver'mculite substantially filling said container, and a thin refractory lining of small heat capacity secured on and supported by the inside of said inner wall.

6. A feeder head as claimed in claim 5 in which said refractory lining is made from a material selected from the group consisting of gannister, compo, ireclay and insulating concrete.

7. A feeder head comprising a tubular container which includes a removable tubular metal inner wall, uncompactedheat 'insulating material substantially -lling said container, and a thin layer of refractory material cast on the inside 'of said inner Wall, said refractory material being yselectedfrom-the group consisting of ,gannis'ten compo, iireclay and insulating concrete.

8. A feeder head 'comprising a 'tubular container which consists essentially in a convergent tubular metal outer wall, an inwardly extending annular metal base integral with said outer wall and located at the bottom `oflsaid wall,.an upwardly extending lip at the inner extremity of said base, a tubular convergent removable metal inner wall retained by said lip on the outer Side thereof, anda 5detachable annular lid bridging said inner and outer walls 4at the top thereof; a quantity of'vermiculite substantially filling said container; and a thin layer of a refractory material selected 'from the group consisting of 'gannisten compo, ireclay and insulating concrete cast on to the inside lsurface ofsaid 'inner wall and supported by saidV lip.

References CitedY in the le of this patent UNITEDv STATES PATENTS 1,388,534 viuage Aug. 23, 1921 1,394;415 Howard et al. oct. 18,1921 1,654,057 smith Dec. l27,1927 1,696,986A Trembour Jan. 1, k1929 1,738,600 Messier Dec. 10, 1929 1,900,066 Mathesius Mar. 7, 1933 1,921,729 Charman ..Y aE Y Y.. -f Aug. 8, l11933 1,982,490 Williams et a1. Nov. 27, 1934 2,231,813 'Mcnonaid Feb. 11,1941 2,462,256 -Charman et al Feb. 22, 1949 FOREIGN PATENTS 300,033 Great vBritain Nov. 8, 1928

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