US790435A - Process of compressing metal ingots. - Google Patents

Description

PATENTED MAY 23, 1905.

R. W. HUNT. PROCESS OF GOMPRESSING METAL INGUTS.

kg MEEV APPLICATION FILED JUNE 22, 1903.

N: 9 mm; W zz/30%;

UNITED STATES Patented May 23, 1905.

ROBERT W. HUNT, OF CHICAGO, ILLINOIS.

PROCESS OF COMPRESSING METAL INGOTS.

SPECIFICATION forming part of Letters Patent N0. 790,435, dated May 23, 1905.

Application filed J'une 22, 1903- Serial No. 162,605.

To all whom it may concern.-

Be it known that I, ROBERT W. HUNT, of the city of Chicago, county of Cook, and State of Illinois, have invented a certain new, use" ful, and Improved Process of Compressing Metal Ingots, of which the following is a specification.- Y

My invention relates to the art of compressing or condensing metal ingots, and-has special reference to a novel process of compress ing large steel ingots, such as are used in the manufacture of armor-plates, ordnance, ships I than the processes of compression that shafts, and the like, for which the best of steel is required.

The object of my invention is to improve the art ofcasting and perfecting large steel ingots; and the particular object of my invention is to provide a simple and adequate process of compressing steel ingots which may be conducted with less machinery and at less cost are now in use.

My invention resides generally in .a process of compressing and perfecting steel ingots that consists in inclosing a mass of molten steel within a closed mold, then allowing the crusts of the ingot to form, then driving a metal bar into the molten mass, and thereby subjecting the same to internal pressure and supplying the deficiency caused. by the shrinkage of the molten metal within the ingot-crusts.

Specifically defined, my novel process consists of the following steps, to wit: pouring the molten steel into a suitable mold, then closing the top of the mold and exerting slight pressure upon the molten contents thereof and permitting the crusts of theingot to form, and then thrusting a bar or mass of suitable metal through the crust of the ingot into the molten interior thereof, thus subjecting the molten contents of the ingot to internal pressure and filling said ingot; and, further, my invention consists in introducing additional masses of metal in time with and in proportion to the shrinkage of the central portion of the ingot.

.M'y invention will be more readily understood by reference to the accompanying drawings, forming a part of this specification, and in which- Figure 1 illustrates the pouring of the informs.

pipe of the ingot.

the filler or pressure-bar having been placed upon the mold. Fig. 3 is a similar view showing the first step of driving the pressure-bar,

and Fig. 4 illustrates the further introduction of the pressure-bar.

Heretofore the compression of ingots has been accomplished by the exertion of external pressure or force upon-the ingot.v I accomplish equivalent and better results by internal pressure. Whenmoltensteel is poured into an ingot-mold, those outer portions of the metal which are in contact with the bottom and the side walls of the mold quickly solidify. This is also trueof the top of the ingot, which is exposed to the air and upon which a thick crust In this way the ingot is cast and takes permanent form while its center is still molten. The molten center cools slowly and as it becomes plastic contracts within the inclosing walls or crusts, which latter when once formed suffer little shrinkage. The contraction or shrinkage of the metal within the walls of the ingot frequently causes the appearance of a large cavity or pipe in the central upper portion of the ingot, and beneath the upper orust thereof. Isolated blow holes are also likely to appear in other parts of the ingot. Commercial steel is rarely pure, the same containing metalloids which part with their heat less readily than the steel proper, and therefore remain liquid for alonger time. Consequently the metalloids are finally excluded from the mass and segregated upon the surfaces of the different cavities and the central Their presence upon these surfaces prevents the welding thereof when the ingot after being reheated is rolled, hammered, or pressed, and said pipe or cavity is therefore only elongated, always constituting a flaw in any article made from the ingot. To avoid such flaws, ithas been the practice to cut off the tops of all ingots used in the manufacture of such articles as armor-plate. The loss entailed is great, and compression has been resorted to to avoid the necessity of cutting ofi the tops of the ingots. Furthermore, it is conceded that the gases which are occluded in molten steel and which develop therein after the steel is poured into the mold l which is placed over the mold 3 and from have much to do with the formation of blowholes and the pipe in the ingot. These gases tend to accumulate in the ingot mass so long as any part thereof remains molten and occupy the space that is left within the ingot- Walls by internal shrinkage. Heretofore it appears to have been accepted that the only way to obviate the formation of the pipe and other cavities was to subject the ingot as a whole to actual compression while cooling, thereby to so far reduce its bulk as to compensate for the internal shrinkage of the ingot and the space that would be occupied by the gases under normal conditions. The accomplishment of compression by external means requires the expenditure of great force by reason of the fact that the walls or crusts 0f the ingot, which from the beginning are quite solid, must be actually compressed or broken down before the interior is effected. The actual reduction of size is slight. My conception is that better results may be accomplished by the introduction of new metal into the molten center of the ingot to subject the same to expulsive pressure or force that will tend to fill the deficient ingot as contrasted with the usual compression of the crusts upon the molten and shrinking center.

My invention is based upon the fact that a closed vessel which is filled with liquid cannot be added to or penetrated by a solid. without greatly increasing the pressure within the vessel, and obviously if an ingot that has partially cooled is pierced and entered by a solid body any cavity which may have formed within the ingot will be filled and more or less pressure will be exerted within the ingotcrust, according to the size of the mass which is driven into the same. By confining the ingot within a heavy mold its Walls may be made to withstand such internal pressure, and I find that heavy internal pressure operates not only to displace the molten metal within said walls, but also actually defiates or collapses the globules or bubbles of gas that may have begun to form within the molten or plastic metal. Such cavities may thus be reduced in size and retained in their initial 10- cations to such an extent that the mass as a whole may be properly termed solid, the blow-holes being so small that they do not affect the strength of the ingot or the article made therefrom. I prefer in carrying out my process to employ a steel bar which after being driven through the crust of the ingot will weld or melt in the top thereof and become a part of the ingot. This may be of better quality than the ingot metal, in which case it will tend to dilute the impurities in the upper part of the ingot.

In the drawings I have illustrated apparatus of simple form and structure, but sufiicient for the performance of my process.

In said drawings, 2 represents a steel ladle which the mold is filled. The mold rests on a stool 4 and is provided with a bottom 6. In connection with the bottom 6 I preferably employ a hydraulic cylinder 5 and piston 7 for elevating said bottom to take up the overall shrinkage of the ingot within the mold. By raising the bottom slowly the ingot may be kept in contact with the walls of the mold throughout the time that the ingot is subjected to internal pressure. The mold 3 may be secured to the stool in any suitable manner, and in practice the stool and mold are preferably movable with respect to the hydraulic cylinder. The mold is provided with a cap 8, which snugly fits the top of the mold, and is placed therein after the mold has been filled and preferably after the top crust of the ingot A has been formed. The cap is provided with a central opening for the filler or pressure-bar B and also contains a driving and locking head 13, which is vertically slidable therein. This head may be provided with ratchets 14, and its expulsion from the cap 8 is prevented by pawls or dogs 15, that engage the ratchets. The cap is secured by wedges 10, arranged in the cars 11 on the mold and bearing upon the side lugs 9 of the cap. The bar B is first placed in the cap and is then topped by the driving-head 13. At this time the lower end of the bar B will rest upon the top crust of the ingot and be in readiness to be driven through the crust. The crust A of the ingot A may be permitted to form and thicken for several minutes before the bar is driven, and it is desirable that said crusts shall become suificiently solid to prevent the bursting or eruption thereof when the molten center or interior A of the ingot receives the bar.

During the cooling of the ingot-crust considerable shrinkage takes place within the same, and the bar may then be driven. For this purpose I employ a heavy hammer 16, one or more blows from which will drive the bar B through the top crust of the ingot and force a portion thereof downward into the molten center of the ingot. The driving of the bar B is continued until the pressure created within the ingot becomes sufiicient to counteract the blow of a hammer or the pressure of a hydraulic piston, which may be substituted therefor, whereupon the operation of the hammer may be stopped until further shrinkage within the ingot makes room for more of the bar B. The driving of the bar will then be resumed and may be continued until the molten center becomes plastic throughout. Meantime that portion of the bar which has entered the molten steel will be melted and incorporated with the ingot metal. I prefer to exert pressure upon the bottom of the ingot throughout the process and gage said pressure to counterbalance or counteract the internal pressure of the ingot plus the weight of the ingot, so that the mold-bottom 6 will follow the ingot as it shrinks within the mold, thereby preventing the separation of the ingot from the mold and making it unnecessary to use a filler-bar B of suificient cubical contents to compensate for the shrinkage of the whole ingot within the mold. In other words, I prefer to employ the bar B only to the extent of supplying the deficiency of metal within the ingot itself.

It is obvious that numerous modifications of my invention will readily suggest themselves to one skilled in the art, and I therefore do not confine the sameto the specific steps and periods herein described.

I do not herein broadly claim the process of perfecting metal ingots by adding thereto a piece of solid metal while the ingot is cooling, as a process thus broadly characterized is described and claimed in my companion application, Serial No. 158,041, entitled Process of perfecting ingots, filed May 20, 1908; nor do I herein broadly claim aprocess that is characterized by the thrusting of a solid bar through the crust of an ingot while the latter is' cooling. Processes thus characterized are described and claimed in my companion applications, Serial No. 158,042

and Serial No. 158,043, filed May 20, 1903,

and both entitled Process of perfecting cast-steel ingots.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The improvement in the art of perfecting or compressing ingots, that consists in completely inclosing a mass of molten metal within a strong mold and permitting all the ingot-crusts to form within the contacting Walls of the mold, and then subjecting the contained molten mass to internal pressure by driving solid metal through one of the ingot-crusts into the molten interior of the ingot, substantially as described.

2. The improvement in the art of perfecting or compressing metal ingots that consists in pouring molten metal into a mold and then Wholly inclosing the mass of molten metal in said mold, then permitting all the crusts of the ingot to form, and then forcibly introducing a mass of like, solid metal into the interior of the ingot while the same is still molten, thereby supplying the shrinkage deficiency of metal within said ingot-crusts, substantially as described.

3. The improvement in the art of perfecting or compressing metal ingots, that consists in wholly completely inclosing a mass of molten metal within a tightly-closed suitable mold, and thereafter introducing an'added mass of solid metal into the central molten part of said ingot mass whilethe latter is cooling, and there dissolving the same, substantially as described.

4. The improvement in the art of perfecting or compressing metal ingots, that consists in completely inclosing a mass of molten metal within a suitable mold, filling said mold, and then gradually driving a mass of metal into the ingot mass, to compensate'for the deficiency caused by shrinkage within the ingot, substantially as described.

5. The improvement in the art of perfecting or compressing metal ingots, that consists in filling a tightly-closable mold with molten metal, then tightly and completely inclosing the molten metal in said mold, and then expanding and filling the early-formed ingotcrusts by internal pressure by forcibly introducing a mass of solid steel, substantially as described.

6. The improvement in the art of perfecting or compressing metal ingots, that consists in casting an ingot, then tightly and completely inclosing the same in its mold, then exerting external pressure upon the end of the ingot, then driving solid metal through the ingot-crust and thereby subjecting the ingot to internal pressure, substantially as and for the purpose specified.

7 The improvement in the art of compressing metal ingots, that consists in Wholly and completely inclosing a mass of molten metal in a taper mold, exerting pressure upon the large end of the cast ingot and driving a metal bar through the small end of the ingot, retaining said bar therein, and thereafter driving said bar farther into said ingot, sub-' stantially as described.

8. The improvement in the art of compressing metal ingots, that consists in completely inclosing a mass of'molten metal in a suitable mold, and thereafter adding successive portions of previously-manufactured metal to the molten interior of the ingot, by driving said'portions through the crust of the ingot at different times, substantially as described.

In testimony whereof I have hereunto set my hand, this 15th day of June, 1903, at Chicago, Illinois, in the presence of two Witnesses.

ROBERT W. HUNT.

Witnesses:

J. W. BROWN, O. G. HAWLEY.

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