US2070532A - Ingot mold - Google Patents

Description

Patented Feb. 9,1937

INGOT om) Emil Gathmann, Baltimore, Md., assignor to Gathmann Research Incorporated, .Catonsville, Md., a corporation of Maryland Application October 11, 1934, Serial No. 747,963

11 Claims.

This invention relates to ingot molds and more particularly to ingot molds or ingot mold assemblies of the kind in which the mold bottom is formed with an opening which is closed by sealing means comprising a plug.

In the co-pending application of Emil Gathmann and Harry S. Bradley Serial No. 731,780, filed June 21, 1934, there is disclosed and claimed an ingot mold assembly including a mold proper having a bottom opening, a cooling plug in the opening, the plug being of material having a coefficient of heat transfer considerably higher than that of the material of the mold proper, and a sealing plate superimposed above the plug and being made of a material having a melting point higher than that of the material of the plug. By means of the invention disclosed in the co-pending application referred to it is possible to produce ingots in which the relative growth of dendritic crystals in a horizontal direction at the lower portion of the ingot is reduced to a minimum and it is thus possible to reduce to a minimum the formation of cleavage planes at the junction of the horizontal dendrites with the vertically-extending free crystals. The arrangement disclosed in the co-pending application has been found to produce consistently good results, that is, a consistently high quality of ingot, with lessened segregation of carbon, sulphur, phosphorus and other elements; but in practice it has sometimes been found time-consuming to locate the sealing plate so that it (1) positively engages the mold so as to seal the bottom opening effectively, and (2) positively engages the top of the cooling plug so as to be in intimate heat-conducting contact therewith.

Anobject of my invention is to provide an improved organization of mold proper, cooling plug within the mold bottom opening, and sealing and heat-conducting means.

Another object is to provide an arrangement of the kind referred to in which the sealing means is adapted to readily be positioned both to engage'the mold bottom for sealing the opening therein, and to engage the cooling plug for transmitting heat from the ingot metal to the plug.

Other objects will be apparent from the following description, the appended claims and the accompanying drawing, in which:

Figure 1 is a central vertical sectional view of a big-end-up mold assembly embodying the invention;

Figure 2 is a similar view of a big-end-down mold embodying the invention;

Figure 3 is a fragmentary vertical sectional view of a modification;

Figure 4 is a horizontal section taken on the line 4-4 of Figure 1 and drawn on a reduced scale; and

Figure 5 is a fragmentary detail view of a sealing cup drawn on an enlarged scale.

The mold assembly shown for the purposes of illustration in Figures 1 and 4 comprises a bigend-up Gathmann mold M positioned upon a stool S supported on a platform P, a combined closure and ingot-cooling assembly 0, and a shrink-head casing or hot top H.

The mold M preferably is made of cast iron or material having a coefficient of heat conductivity comparable with that of cast iron, and is provided with bottom opening I which flares outwardly at its lower end 2 and which extends downwardly from the necked-in bottom portion 3 of the mold. The invention may be embodied in mold assemblies in which the molds proper may have any suitable cross-sectional contour, the contour shown in Figure 4 being by way of example only. Preferably, however, when a bigend-up mold is used, the vertical sectional contour of the mold at its lower necked-in part 3 should be similar to that contour disclosed in my co-pending application, Serial No. 738,128, filed August 2, 1934.

The closure or cooling assembly'C includes a massive plug 4 having an upper portion 5 disposed within the mold bottom opening I and a reduced lower portion 6 disposed within an opening 1 in the stool S. A shoulder 8 intervening between the upper and lower plug portions 5 and 6 rests upon the top of the stool S, thus serving to support the plug in the position shown. In order to securely lock the plug to the stool, the lower part i of the plug extending beyond the bottom of the stool may, if desired, be formed with 'a transverse bore 9 adapted to receive a pin [0 insertable and withdrawable through openings II on the platform P.

The plug 4 is employed primarily for cooling purposes, i. e., for rapidly extracting heat from the central zone of the bottom portion of an ingot cast in the mold M and to this end preferably is constructed of material having a coeiiicient of heat conductivity several times that of the material of the mold proper. Preferably the plug may be made of copper or a suitable copper alloy, copper having a coeflicient of heat conductivity approximately eight times that of cast iron of which ingot molds are usually constructed. The plug 4 is not relied upon primarily for sealing the mold bottom opening against the egress of molten metal, and therefore, it is permissible and in fact desirable to provide a substantial clearance l2 between the upper part 5 of the plug and the walls of the mold bottom opening. This clearance may be, for example, from one-sixteenth to three-thirty-seconds of an inch. With this substantial clearance and with the bottom of the mold bottom opening flaring outwardly as at 2, ms easyto lower the mold over theplug'without taking great precautions as to centering the mold with respect to the plug and without danger of striking and mutilating the relatively soft copper plug. Further to assist in the rapid assembly-of the parts, a clearance I3'may'be provided between the lower part of the plug and the opening 1 in the stool. 5

The present invention relates more particularly to means for sealing the mold bottom opening against -the egress of molten metal and at the same-time for rapidly conducting heat from the ingot metal to the cooling plug 6. In a preferred embodiment the sealing means includes a plate '14 disposed above and resting upon the top of I disc portion l5 disposed above and in heat conthe cooling plug, and a sealing cup l5 having a di ,ing engagement with the plate I4, and a circumferential flange l5 in sealing engagement with the walls of the bottom opening I.

The plate and cup are madeof material which is more resistant to the cutting action of molten steel, i. e., of. a higher melting point, than the material in the plug 4. Ordinary sheet steel which has been found to possess the thermal requirements necessary for proper functioning of heat from the bottom of the ingot to the cooling yplug 4.. The functions of the plate and sealing cup are to protect the plug from the cutting action of the molten steel yet rapidly to conduct heat from the ingot mold to the plug, and to seal the -mold bottom opening. I have found that when the plate has a thickness of from one-eighth inch to one-quarter inch and the disc portion l5 of the cup has a thickness of aboutone-eighth inch, the mold bottom opening will be sealed effectively and the plug protected without undue retarding of the transfer of heat from the ingot to the plug. The combined thickness of the plate and cup disc portion having the dimensions referred to is sufficient to protect the plug from the cutting action of the molten steel yet is not great enough to interfere substantially with the transfer of heat.

The plate l4 preferably is of a diameter slightly less than the diameter of the mold bottom opening so as to provide for clearance I6 which facilitates setting of the plate within the opening without the pecessity of maintaining accurate dimensions which is difficult to accomplish under the conditions existing in ingot casting plants. Inasmuch as the cup is constructed of thin material, its flange l5 is somewhat resilient so that the flange, being made of slightly greater diameter than the mold bottom opening, will be forced inwardly when the cup is inserted from above, the flange thereby being caused to contact the walls of the opening forcibly so as to provide an efiective seal for the opening. It will be understood that if the distance from the top of the plug to the top of the mold bottom opening varies somewhat in different assemblies or set-ups, the

' functions. I

Inasmuch as the cup I5 is constructed of such light metal, it may in some cases become hot enough-to be welded to the walls of the mold bottom opening; and to prevent such welding I may coat or slurry the outer face of the flange with fire resisting cements, paint or the like or I may glue astrip of paper I5 to the outer face of the flange so that the paper will be interposed between the flange and the mold. Ordinarily this interposed weld-preventing material will be destroyed more or less by the heat of the ingot metal but the residue will prevent welding of the flange to the mold, thus preventing sticking of the cup within the. mold when the ingot is stripped from the mold.

In order to assure pouring of the molten metal directly upon the cup l5 so as not to cut the necked-in portion 3 of the mold, a shrink-head H or other device may be provided with a relatively restricted pouring opening I! disposed directly above the cup I5. By this arrangement the stream of metal entering through the opening I! must of necessity impinge upon the cup and not upon the necked-in part of the mold. It will be understood however, that even though the stream of metal does not impinge directly upon the necked-in part of the mold the splash from the cup during the initial stages of pouring may have some cutting effect upon the necked-in walls, and for this reason I preferably make the thickness of the moldbottom wall relatively great was to increase the rate of heat absorption from the surface of the necked-in walls 3. Preferably the depth of the bottom opening I and, hence, the minimum thickness of the mold bottom wall indicated by the dimension a. should be not less than one-fourth b, the diameter of the opening, and preferably should be about one-half b or even greater in order to obtain the desired rapid extraction of heat from the ingot. The depth 0 of the upper portion of the cooling plug should be not less than one-quarter the diameter 1) and preferably should be about one-half b.

In assembling the various parts shown in Figure 1 preparatory to pouring an ingot, the plug 4 is positioned on the stool S with the lower portion 6 of the plug extending downward through the opening I in the stool, and the pin IQ positioned in the transverse bore 9 so as to lock the plug securely to the stool. The mold is then lowered onto the stool so that the upper portion 5 of the plug will be extended into the mold bottom opening, after which the plate M-is laid or positioned upon the top of the plug. Then the cup I5 is placed in the opening withits flange l5 frictionally and forcibly engaging the walls of the mold bottom opening, and is forced downward until the disc portion l5 engages the top of the plate It. The cup, plate and plug will then be inheat-conducting relation, and the bottom opening will be sealed. Finally, the shrink-head casing H stream centering device is placed in position on top of the mold with the pouring opening I l directly above the cup l5.

When molten steel is poured into the mold, it

- which is in turn positioned will impinge directly upon the cup l5, which, in conjunction. with the plate, will protect the relatively soft cooling plug, which is relatively vulnerable to. the cutting action. of falling molten steel, against erosion. and oxidation. The plug,

which is highly heat-absorptive, will extract heat rapidly from the bottom of the ingot through the cup and plate so as. to: chill the ingot locally and thereby to. prevent the formation of the cleavage planes hereinbefore. referred to. ,If any marginal portion of the cup should be melted by the hot steel, the small amount. of steel which might leak. past the edge of the cup would be chilled and solidified before it could run out through the clearance space l2. Becauseof this double sealing arrangement, the plate 14 and cup l may be made of very thin material which is inexpen sive and does not interfere appreciably with the transfer of heat from the ingot to the cooling plug.

In the modification shown in Figure 3, a bigend-up mold M is shown as having the same general characteristics and construction as the mold M in Figure 1, and is supported upon a stool. S

The mold has an opening I flared outward at its bottom as at 2' for the reception of a cooling plug 4 which is formed integrally with the stool S. The plate l4 and the sealing cup l5 are of the same construction as the plate [4 and sealing cup l5 shown in Figure 1, and are assembled in the same relation to the cooling plug and mold as in Figure l. The sealing and cooling functions of the various parts disclosed in Figure 3 are the same as the corresponding functions of like parts shown in Figure 1. Either theFigure 1 or the Figure 3 construction is entirely suitable for use when big-end-up molds are employed, the particular arrangement used being determined by sho'p conditions and existing equipment.

In Figure 2 the invention is disclosed as embodied in an assembly including a big-end-down mold M" which is open at its bottom end and which is supported upon a stool S"-forming in effect the bottom of the mold, the stool being positioned upon a platform 'P". The. stool is formed with an opening l8 which is flared out- Ward at its upper end I!) and which is reduced in diameter. at its lower end as at 20, thereby forming a shoulder 2|. A plug 4" is positioned within the opening l8'and is formed with an enlarged upper portion which rests upon the shoulder 2| and with a transversely extending bore 9" through which a pin Ill" .extends for locking the plug to the stool. Holes ll" serve to permit insertion and withdrawal of the pin H). A plate l4" and sealing cup l5" are constructed and positioned similarly to the plate I4 and cup 15 of Figure l, and function in the same manner as the latter.

The materials employed for the cooling plugs, plates, and sealing cups of the assemblies shown in Figures 2 and 3 should be the same as or selected with the same conditions in view as the materials forming the corresponding parts of the Figure 1 assembly. Similarly, the relative dimensions and the clearances provided should be the same as those in Figure 1.

It is apparent that I have provided a combined ingot-cooling and mold-closing assembly adapted effici ently to perform the functions of rapidly chilling the central zone of the bottom portion of the ingot and sealing the mold bottom opening against the egress of molten metal, the arrangement being such that the parts may be rapidly upon a platform P.

assembled in the necessary cooperative relationship without undue loss of time heretofore encountered in the more or less delicate fitting of the parts required to bring the sealing means into heat-conducting contact with the coolingmeans and at the same time into sealing contact with the mold. Various changes may be made in the specific construction and relative arrangement of the parts without departing from the invention as defined in the claims.

I claim:

1. An ingot mold assembly comprising a mold proper havinga bottom opening; a massive plug in said opening and being made of material having a coeflicient of heat conductivity several times that of the material of the mold proper;

a metallic plate lying on top. of and in heat conducting engagement with said plug and being of material relatively less vulnerable to the cutting action of falling molten steel than the material forming the plug; and a cup-shaped metallic sealing element on top of and in heat conducting engagement with said plate.

2. An ingot mold assembly comprising a mold proper having a bottom opening; a massive copper plug in said opening; a metallic plate lying on top of and in heat conducting engagement with said plug and being less vulnerable to the cutting action of falling molten steel than said plug; and a cup-shaped metallic sealing element on top of and in heat conducting engagement with said plate, said sealing element having an upstand ng circumferential flange resiliently engaging the walls of the mold bottom opening.

3. An ingot mold assembly comprising a mold proper having a bottom opening; a massive plug in said opening and being made of material having a. coefficient of heat conductivity several times that of the material of the mold proper;

a metallic plate lying on top of and in heat conducting engagement with said plug and being of material relatively less vulnerable to the cutting action of falling molten steel than the material forming the plug; and a cup-shaped metallic sealing element on top of and in heat conducting engagement with said plate, said sealing element comprising a horizontal portion relatively thin.

as compared to said plate, and a circumferential flange portion in engagement with the walls of the mold bottom opening.

4. An ingot mold assembly comprising a cast iron mold proper having a bottom opening; a massive copper plug in said opening; and a sealing cup having a thin horizontal portion above and in heat-conducting relation to said plug, and

a circumferential flange in engagement with the walls of said opening and being of material relatively less vulnerable to the cutting action of falling molten steel than the material forming the plug.

5. An ingot mold assembly comprising a'mold proper having a bottom opening; a massive plug in said opening and being made'of material having a coefficient of heat conductivity several times that of the material of the mold proper;

a metallic plate lying on top of and in heat conducting engagement with said plug and being of material relatively less vulnerable to the cutting action of falling molten steel than the material forming the plug; and v a cup-shaped metallic sealing element on top of and in heat conducting 'engagement with said plate, the thickness of said plate being from one-eighth to onequarter inch and the thickness of said sealing element being about one-eighth inch.

proper having a bottom opening; a massive plug in said opening and being made of material v action .of falling molten steel than the material forming the plug; and a cup-shaped metallic sealing element on top of andin heat conducting engagement with said plate, the depth of said mold bottom opening, and hence the thickness of the mold bottom, being at least one-third the diameter of the opening. 7. An ingot mold assembly comprising a mold proper having a bottom opening; a massive plug in said opening and being made of material hav-' ing a coeflicient of heat. conductivity several times that of the material of the mold proper; a metallic plate lying on the top of and in heat conducting engagement with said plug and being of material relatively less vulnerable to the cutting action of falling molten steel than the material forming the plug; and a cup-shaped metallic sealing element on top of and in heat conducting engagement with said plate, the depth of the portion of the plug disposed Within the opening being at least one-fourth the diameter of said opening.

8. An ingot mold assembly comprising a mold proper having a bottom opening; a massive plug in said opening and being made of material having a coefilcient' of .heat conductivity several times that of the material of the mold proper; a metallic plate lying on top of and in heat conducting engagement with said plug and being of material relatively less vulnerable to the cutting action of falling molten steel than the material forming the plug; and a cup-shapedmetallic sealing element on top of and in heat conducting engagement with said plate, the depth of said mold bottom opening, and hence the thickness of the mold bottom, being at least one-third the diameter of the opening, and the depth of the portion of the plug disposed within the opening being at least one-fourth the diameter of said opening. 9. An ingot mold assembly comprising a mold 2,070,682 6. An ingot mold assembly comprising a mold proper having a bottom opening; a massive plug in said opening and being made of material having a coefiicient of heat conductivity several times that of the material of the mold proper; a metallic plate lying on top of and in heat conducting engagement with said plug and being of material relatively less vulnerable to the cutting action of falling molten steel than the material forming the plug; and a cup-shaped metallic sealing element on top of and in heat conducting engagement with said plate, said sealing element being adapted to engage the walls' of said opening at different positions therealong whereby said sealing element may be disposed in heat conducting relation to the plug and in sealing engagement with the walls of the opening irrespective of relatively small variations inthe distance I from the top of the opening to the top of the plug.

10. An ingot mold assembly comprising a cast iron ingot mold: having a bottom opening; a

closure for said bottom opening consisting of massive relatively thick copper material and a relatively thin sealing cup of ferrous sheet material superimposed above and in heat-conducting relationship to said copper material and having a circumferential vertically extending flange in engagement with walls of said mold bottom opening. 4

11. An ingot mold assembly comprising a mold proper having a bottom opening; a massive plug in said opening and being made of material having a coefiicient of heat conductivity several times that of the material of the mold proper, said plug being of such size as to leave a substantial clearance space between its periphery and the wall of said mold bottom opening; a metallic plate lying on top of and in heat-conducting engagement with said plug and also being of such size as to leave a clearance between its periphery and the wall of said mold bottom opening; said plate being of material relatively less vulnerable to the cutting action of falling molten steel than the material forming said plug; and a cupshaped sealing element on top of and in heatconducting engagement with said plate and having a flange engaging the wall of said mold bottom opening.

EMIL GATHMANN.

Images