US1661039A - Ingot mold - Google Patents

Description

Feb. 28', 1928.

\ E. GATHMANN INGOT MOLD Filed March 15 1927 QB l i so

Patented Feb. 28, 1 928.

UNITED STATES PATENT OFFICE.

EMIL GATEIANN, OF BALTIMORE, MARYLAND.

i IN'GOT MOLD.

Application filed March 15, 1927. Serial No. 175,527.

solid, the horizontal length and width of' which ingots are materially greaterthan. the vertical height. Such ingots are more economically reduced by forging and roll-' ing mill operations'to plates, sheets and various other units than are ingots made by the more widely used method of so-called vertical casting.

Prior to my invention ingots'have been cast in what are known to those familiar with the art as horizontal molds, i. e.,.molds in which the longitudinal axis of the mold chamber is disposed horizontally. In the use of such molds, however, longitudinally extending pipes or shrinkage cavities have been formed in the ingot, and in steel and other alloyed metals cast in such molds segregation of the various elements has occurred to a dangerous degree, so that when the ingot is rolled into commercial shapes or units, some parts are sound and uniform while others are unsound or have widely varying physical and chemical characteris tics, thus causing stresses to be set up in the semi-finished product, which render it liable to break or split during the process of manufacture or in its use.

By my improvements I am enabled to produce an ingot of the horizontall cast type, which is free from pipe andshrmkage cracks and in which the segregation may be 40 to a great extent controlled. For certain products it 'is desirable to reduce segregation to a minimum, which I have made pos sible by reducing the depth of the ingot relative to its width to induce rapid freezing of the entire mass. For certain other products, such as boiler plate, segregation can be distributed substantially evenly over the upper plane of the ingot by providing any well-known means for retaining the metal molten at its upper surface for the desired length of time to obtain the amount of segregation required for the particular product. The mold made in accordance with my invention preferably has a long, horizontally-arranged major axis and a relatively narrower transverse axis. The height or depth of the mold chamber is less than its width for reasons hereinafter explained. The side walls defining the ingot-forming chamber preferably gradually decrease in a thickness upwardly and the bottom wall,

which is relatively thicker or more heat-absorptive than the side walls, is formed with a chamber or rise which projects into the mold chamber in such a manner as to absorb heat more rapidly from the middle or central longitudinal section of the 'molten metal than from adjacent portions thereof, thereby causing the metal of theingot to solidify vertically in its middle and ad'oining portions in a substantially uni orm' manner and more rapidly than it is being solidified laterally or horizontally from the side walls of the mold. Experience has demonstrated that when the mold walls have these characteristics and the chamber is properly dimensioned, the freezing or solidifying of the molten metal will be completcd in less time for a given mass of metal than has heretofore been possible and the shrinkage of the mass will be of such a character that no pipe is formed either at the top or at the ends of the ingot and that segregation, due to the rapid rate of solidification of the molten'metal, will be readily controlled.

My improvements are illustrated in" the accompanying drawings, in which-- Figure 1 is a perspective view of a horizontal mold made in accordance with my invention, portions of the mold being omitted for convenience of illustration.

Figure 2 shows a vertical transverse section on lines 2-2 of Figure 1.

Figure 3 shows a section similar to thatv shown in Figure 2 with the solidified ingot shown in .cross section in the mold cavity.

Figure 4 shows'a longitudinal section of the mold on lines 44 of Figure 1 and illustrates also a longitudinal central section of the ingot cast in the mold.

Figure 5 is an enlarged view in perspective of a portion of the ingot.

Figure 6 is a perspective view of a portion of a plate or sheet rolled from an ingot such as shown in Figure 5.-

The mold made in accordance with m invention is preferably of cast iron, whic is commonly used in the manufactured V8- mold chamber walls, usuallythrough formation of dendritic crystals, until solidification is complete.

In vertical molds of now well-known design, this solidifying process of the ingot is so controlled by means of big end up mold chambers and refractory shrink head casings that the so-called pipe orshrinkage cavity is greatly reduced andfconfined to a relatively small part of the ingot at its top. In the casting of ingots in horizontal molds, however, a decided shrinkage pipe, cavity or crevi'se has heretofore been formed, which usually extends longitudinally from one end of the ingot to the other, being deepest and most pronounced near the center of the mass of the ingot, which is always last to cool and solidify, at which Izone segregation is likewise concentrated.

By my invention I so shape the mold chamber thatthe moltenmetal of the ingot will solidifyin its central longitudinal portion in substantially the same period of time as the side or surrounding portions and the ingot isso formed that what is known as cleavage cones and ingotism or the forma- .tion of large crystals in the structure of the ingot are greatly reduced. The bottom or base of the ingot surface being inwardly hellied or cambered to an extent proportional to the width and depth of the mold chamber and in ratio to the volume of the shrinkage of the metal forming the ingot during solidi fication, the formation of shrinkage cavities or pipes is prevented by compensating for and forcing the contraction of the metal in vertical planes during solidification. A

slightly dished or camberd portion at the upper face of the ingot is sometimes formed therein, but concentrated shrinkage cavities or piped zones are entirely prevented. In this way 'a great saving is effected, as the 7 percentage of sound metal which can be rolled or forged into commercial shapes is approximately the entire ingot, less only the usual scale and trimming loss of ,i% to 6%.

An important feature of the invention is that the walls defining the mold chamber are of such contour and heat absorptive quality that the molten metal will cool, solidify and shrink in a substantially vertical direction from the bottom upward in approximately the same period of time at all vertical planes, as the depth of the'liquid ingot metal in the mold chamber at its central longitudinal portion is proportionately less and the cooling action of the mold walls greater than at adjacent portions of the chamber.

The drawings illustrate one way of con; i

structing a mold in accordance with my invention. The mold is made of cast iron of the kind usually employed. The bottom B thinner and less heat absorptive, gradually i decrease in thickness from their lower to their upper ends,thus insuring that the solidification of the moltenmetal of the ingot will be progressively upwards, the same rule applying in the formation of the sidewalls a, ofthe horizontal, molds as applies in the for Q mation of side'walls'of vertical molds. The 7 bottom wall of-my horizontal mold, however, differs from the bottom wall of other molds. It will be observed that the bottom wall, in addition to being relatively thick and heavy and thus more heat absorptive than the side walls, is formed with a longitudinal rise oricamber X, which projects to its highest part at the central or middle T longitudinal portion of the mold chamber, so that as the molten metal cools, shrinks and solidifies coincidently in the middle portion of the mold with thatof all adjoining portions, the entire mass of metal becomes solidified without pipe or shrinkage cavity being formed therein; The rise X may have various contours but is preferably cambered in the form of a convex are as shown, the amount of this rise being governed by the depth and width of mold chamber and the character of the ingot metal for which the mold is designed. i

As previously stated, the height of the mold chamber or that part thereof in which,

used for sheet bar pi oduct.

The exact If the width of the mold chamber at its top is 12", the greatest height of the chamber should be approximately 8", while its height from the top of the rise X should be about 7 The over-all height of the mold should be approximately l3", the distance from thebottom face ofthe mold to the top of the rise X thus beingabout 6'7. The

taper of the mold chamber from top to bottom should be approximately A,".

These relative dimensions have given satisfactory results'in actual test, but may and should be varied to correspond with specific conditions and requirements. The mold may be of any desired length within limita- Any length to which the" metal canv tion. flow without danger of laps or cold shuts may be utilized.

It will be understood by those familiar with the art that the liquid metal of an in got solidifying in a metallic mold is invariably hottest for a longer period of time at the central or middle portion of its mass than atadjacent portions of the ingot unless means are utilizied to accelerate its cooling. By my improvement there is less vertical height of ingot to, cool at the center of the mass than at adjacent transverse parts, so that the rate of vertical cooling. within the limits specified, can be adjusted to obtain uniform solidification.

The method of teeming or pouring the metal into my improved type of mold and the stripping of the ingot therefrom is not a part of this invention. Various well-known methods have been found satisfactory.

Referring to Figure 5 of the drawings, I have illustrated by dotted lines, a, 7), c and (Z, the manner in which solidification of the ingot occurs.

.In Figure 6 of the drawings I have shown in perspective a portion of a plate showing the uniformly segregated zone portion in dotted lines, this portion having been the last of the ingot to solidify.

It will be observed that the ingot formed in the manner hereinbetore described. has two primary side walls, that is, the bottom and top of the ingot. and four secondary walls, namely, the longitudinal sides and the ends. It will also be observed, by reference to Figure 5 particularly, that all corners are well rounded. By such a construction most ellicient heating and rolling can be obtained without danger of burning or cracking during these operations.

I claim as my invention:

1. A horizontal metallic ingot mold having a chamber. the bottom wall of which is relatively thicker and thus more heat absorptive at its central longitudinal than at its adjacent longitudinal portions.

2. A horizontal metallic ngot mold having a relatively long and shallow chamber the depth of which is less than its widthand the bottom wall of which is cambered or upwardly bellied. whereby the depth of said chamber is less in its central longitudinal section than in its adjacent longitudinal portions.

3. A horizontal metallic ingot mold having a relatively longand shallow chamber, the bottom of which is formed of a convex or upwardly cambered contour.

4. A metallic mold having a relatively .shallow chamber with vertical side walls which gradually decrease in thickness up wardly and a horizontally disposed bottom wall which is formed with a camber which projects into the mold chamber between the side walls and which is more heat absorptive than the side walls.

5. An ingot mold having a horizontal relatively shallow chamber and having side walls the inner faces of which extend upwardly and outwardly fi'om the bottom Wall of said chamber. the said lottom wall being formed of a camber-cl or upwardly bent contour.

6. An ingot mold having a horizontal relatively shallow chamber. the width of which is materially greater than its height. and having vertically extending side and end walls and a bottom wall which is relatively thicker and thus more heat absorptive atand near its cen ral longitudinal portion than at adjacent longitudinal portions.

7.-.-\ metallic mold having a horizontal relatively long and shallow ingot-forming chamber defined by vertical side walls and a bottom wall which is more heat absorptive than the side walls and which is formed with a curved or arched portion which procentral longitudinal part of said bottom wall being thicker and thus more heat absorptive than its side portions.

9. A horizontal metallic ingot mold having a relatively long and shallow chamber the bottom of which is tormed of a convex or upwardly cambercd contour and the side walls of which gradually decrease in thickncss from the bottom to the top of the mold.

In testimony whereof. I have. hereunto subscribed my name.

EMIL GATHMANN.

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