US805729A - Process of perfecting cast-steel ingots. - Google Patents

Description

No. 805,729. PATENTED NOV. 28, 1905. R. W. HUNT.

PROCESS OF PERFEGTING CAST STEEL INGOTS.

APPLICATION FILED MAY 20. 1903. RENEWED MAR. 23, 1904.

2 SHEETS-SHEET 1.

v KW.

PATENTED NOV. 28, 1905.

R. W. HUNT. PROCESS OF PERFEGTING CAST STEEL INGOTS.

2 SHEETSSHEET 2.

APPLIUATION FILED MAY 20. 1903- RENEWED MAR. 23, 1904.

UNITED 'STATES PATENT OFFICE.

Specification of Letters Patent.

Patented Nov. 28, 1905.

Application filed May 20, 1903. Renewed March 23, 1904;. Serial No. 199,626.

'10 ail whom it may concern:

Be it known that 1, ROBERT W. HUNT, of the city of Chicago, county of Cock, and State of Illinois, have invented a certain new, useful, and Improved Process of Perfecting Cast-Steel Ingots, of which the following is a specification.

My invention relates to improvements in the art of manufacturing cast-steel ingots, particularly those intended to be made into rails and beams.

The process of casting ingots as now commonly conducted in a rail or beam mill is as follows: The molten steel is taken from the converter and poured into the ingot-mold with the least possible delay. The filled mold then makes way for another and is allowed to stand until the ingot becomes suflicientlysolid to retain its form, whereupon the mold is stripped from the ingot. Then the partiallycooled ingot is taken to the soaking-pit or reheating-furnace and is there heated until its temperature becomes uniform throughout. Upon the completion of this process the ingot is removed from the soaking-pit and is ready to be manufactured into rails. An ingot which is made and treated in this manner is apt to be piped-that is, to contain a large central cavity. Commercial steel contains considerable quantities of various metalloids, and when a cavity forms within an ingot the metalloids collect upon the walls of the cavity and there refuse to weld when the ingot is reheated and compressed or rolled. As a result the rails which are made from piped ingots are worthless and should be discarded. Not infrequently, however, they escape detection and being placed in use cause disastrous railroad wrecks. The present value of the manufactured product is such that the entire process of casting and rolling rail-steel ingots to be profitable must be conducted with celerity and with as little labor as possible.

Although it'is possible to produce sound ingots, the known precautions against extensive piping involve prohibitive outlays of time, labor, or material and are generally disregarded. Thus such measures as the slow pouring of ingots, the packing of the tops thereof, the spraying thereof, the subjection of the ingots to heavy internal and external pressure, the insertion, expansion, and welding of large masses of steel there n and therewith all require too much time. occasion too many delays, and are too expensive in labor and material to admit of their use in a rail or beam mill.

The object of my invention is to improve the abo 'e-described process in ways and by means that shall operate to imprt-re the quality of steel ingots and which shall neither prolong the work of a steel-mill as usually performed nor materially add to the cost thereof.

Another object of my invention is to provide a process of casting and perfecting steel ingots that shall admit of the perfecting of the ingot at the moment preceding the removal of the mold from the ingot. a distinct purpose being to avoid interrupting or delaying the regular run of work as now commonly observed.

The particular object of the invention is to provide a process of casting and perfecting steel ingots that shall operate to fill or replenish internally shrunken or piped ingots and exclude the gases and metalloids from the axial or central portion of the ingot and cause the gases either to be retained substantially in their original states of occlusion and suspension or to accumulate in a shallow cavity in the extreme top of the ingot.

My novel process is coextensive with the process in common use and consists in casting molten steel in a mold, then permitting the walls or crusts of the ingots to form preparatory to stripping the mold from the ingot, then placing the mold in position to be oper ated upon by the stripping-machine, then by the introduction of a relatively small steel bar or rod initiating and forcing the solidification of the central or axial portion of the ingoti. 6., creating from and in the central portion of the ingot mass an initially small but increasing solid column of plastic or denser steel, thereby filling or replenishing the ingot and excluding from its central portion the gases and metalloids that would otherwise tend to form an objectionable pipe then stripping the mold from the ingot, and finally reheating the ingot all preparatory to the working of the ingot.

The invention will be more readily understood by reference to the accompanying drawings, forming a part of this specification, and in which I have illustrated the apparatus and the steps incident to the carrying out of my process.

In said drawings, Figure 1 illustrates the pouring of an ingot. Fig. 2 illustrates the ingot-perfecting and mold-stripping machine, the perfecting-rod being shown in position ready to be driven into the ingot by the descent of the stripping-machine. Fig. 3 is a similar view illustrating the driving of the rod and showing the complete mechanism employed for the purpose. Fig. 4 illustrates the final driving movement. Fig. 5 illustrates the stripping of the ingot. Fig. 6 is a perspective detail of the rod-holding device, and Fig. 7 is a sectional view thereof when in the dotted-line position of Fig. 3. The soakingpit or reheating-furnace being well known is not illustrated.

In carrying out my process the molten steel is poured into the mold and allowed to stand therein until the top crust of the ingot A has formed and gained considerable thickness and solidity. In the meantime a pipe or cavity may have begun to form within the ingot, its size depending upon the quality of the steel and the internal shrinkage of the ingot. The non-presence or the presence and extent of the pipe or blow-holes in the ingot may be due to many and varying conditions, all of which may now be ignored because of the employment of a bar, rod, or mold-piece B, which I thrust, preferably, through the top crust of the ingot just before the mold is stripped from the ingot. The introduction of the rod and its presence in the ingot serves to materially reduce the temperature within the axial portion of the ingot. This lowering of the temperature initiates and forces the solidification of the central mass, and thus checks the natural inwardly directed segregation of the metalloids and the gases in the molten metal and operates to expel the same from the central portion of the ingot. The quality of the metal constituting the central portion of the ingot is thus much improved as compared with the same portion of an ingot made in the old way. In addition to this improvement of the ingot I preferably employ a bar or billet B, that is of better steel than the ingot mass A and which upon being thrust into the molten center of the ingot melts therein and further raises the quality of the steel at the center of the ingot. The rods used in different ingots need not be of the same length that is, I prefer to fix the size thereof according to the internal pressure that the ingot-walls and the mold will stand or according to the cubical capacity of the pipe or cavity that is likely to form within an ingot composed of steel of a given kind and quality.

In the drawings, 2, 3, and A represent the ingot stool or car, the ingot-mold, and the ingot, respectively. The same car, the same mold, and the same ingot are shown in the different figures of the drawings, which figures represent the three important steps in the process of casting and perfecting the ingot.

4 in Fig. 1 represents the ladle that receives the steel from the converter and from which theingot-moldisfilled. Aftertheingotiscast the filled mold is taken to a convenient place to cool, as the mold cannot be stripped from the ingot in any case until the walls and the upper crust of the ingot have become solid enough to withstand the pressure of the plunger of the stripping-machine. When the ingot finally arrives at the stripping-station, its upper crust and its walls are of considerable thickness; but the interior of the ingot is still molten. As a rule the pipe or cavity, if any exists, is quite fully developed by the time the'ingot is ready to be stripped, and the center of the ingot becomes solid or se-miplastic very quickly after that operation, the external walls of the ingot being then exposed to the air. Previous to the stripping of the ingot the perfectingrod may be driven into the ingot with little difliculty and will accomplish the results desired, while if the insertion of the rod should be delayed until the interior of the ingot becomes plastic little good would be done beyond the mere displacement of the metal within the ingot-walls to fill any cavity therein. The ingot is therefore perfected at the moment preceding the removal of the mold therefrom, at which time the mold serves to supplement the strength of the ingot-walls and prevent the distortion or rupturing thereof by the momentary pressure that sometimes occurs when the rod enters the ingot. In carrying out this step of my process I prefer to employ the usual stripping-machine, adding thereto a mechanism for holding the rod or billet While the same is being driven. The

I weight of the stripping-machine is utilized for driving the rod or billet into the ingot. Said stripping-machine usually comprises a vertically and laterally movable frame 6, provided with lifting hooks 0r lugs 7 and a hydraulic plunger 8. The lifting-hooks are adapted to engage the lugs 3 on the molds and are operated in any convenient manner, as by the hydraulic engine 7. The stem 8 of the plunger is connected with a piston in the vertical cylinder 9. Suitable hydraulic connections are provided for the cylinders 7 and 9, whereby the hooks and the plunger may be operated. The rod or billet holding device comprises a block 10, having a groove 10 to receive therod or billet B and also provided with a wide base or flange 10 to rest upon the top of an ingot-mold beneath the stripping-machine. The rod is preferably held in place by means of tongs 11, provided in the block. The block is of less length than the shortest rod to be held thereby. It is pivoted to the end of the horizontally-movable beam 12. This beam is 0perated by the hydraulic or s eam engine 13 and rides upon the spring-borne rollers 11 in l the frame 15.

16 represents larger rollers whereon the block is elevated and thrown into a horizontal position when the beam 12 is drawn back. The tongs 11 are held closed by a weight 17, connected thereto by a cable 18.

19 is a device for lifting the weight when it is desired to release the tongs, same being arranged for fluid operation.

When a filled mold arrives at the filling and perfecting station, it is placed beneath the stripping-machine. At this moment the rodholding device will be in the position shown by dotted lines in Fig. 3 with the tongs open. The rod B, which has been previously heated, will then be placed in the block 10 and the tongs will be closed thereon by dropping the weight 17. The rod is then ready to be placed over the mold. Thereupon the beam 12 is thrust forward and the block moves into the vertical position and by means of the cylinder or engine 13 is accurately placed over the center of the mold. The stripping-machine is then dropped upon the rod, its plunger striking the upper end thereof and driving the rod down with such force that the lower end of the rod pierces the top crust of the ingot in the mold, as illustrated in Fig. 3. The tongs 11 are then released and the block 10 is removed to permit the further descent of the stripping-machine todrive the rod fully into the ingot, as illustrated in Fig. 4:. The stripping-machine will now be in position for engagement with the mold and its links may be immediately swung beneath the lugs 3 on the mold. The plunger of the stripper is then projected, driving the rod home. The admission of fluid under pressure to the cylinder 9 to project the plunger obviously operates also to elevate the stripper-frame. This operation may be assisted by the upper cylinder of the stripper and results in stripping or lifting the mold from the ingot. In the meantime the entrance of the rod into the molten portion of theingotdisplaces the molten metal and forces the same upward, thereby completely filling any pipe or cavity within the ingot. This first and natural result of the introduction of the rod isimmediately followed by the equally important chilling or cooling of the central or axial portion of the ingot by reason of the lower temperature of the rod. The lowering of the temperature in the center of the ingot causes the same to become plastic within a very short space of time and results in the dispersi-n of the small quantity of metalloids and gases from the axis of the ingot. The greater quantity of the metalloids that may have c-llected upon the walls or at the bottom of the pipe or cavity prior to the entrance of the rod being still liquid will have I been displaced and forced into the extreme 1 top of the ingot or discharged through the hole around the rod at the instant following its entrance. The rod or billet B is made of steel similar to the ingot steel, but preferably of better quality, and it quickly melts within or welds with the ingot mass, serving to further improve the quality of the metal at the center of the ingot. The final step of the process consists in reheating the ingot.

A similar but distinctly different process of casting and perfecting steel ingots is shown and described in my pending application, Serial No. 158,042, filed Way 20, 1903.

As numerous modifications of the invention will readily suggest themselves to one skilled in the art, the same is not confined to the specific steps, features, materials, or devices herein shown and described.

Having thus described my invention, I claim as new and desire to secure by Letters Patent 1. The herein-described improvement in the art of casting and perfecting simple ingots that consists in casting the molten metal in a mold, then permitting the ingot to cool preparatory to the stripping operation, then driving a relatively small bar or rod of like metal through the end crust of the ingot and lodging the same axially within the ingot, thereby initiating and forcing the formation of n initially small but increasing column of denser or plastic metal from and within the ingot mass, then immediately removing the mold from the ingot, and, finally, reheating the ingot, substantially as described.

2. Theherein-described im'provcmentin the art of casting and perfecting simple steel ingots, that consists in casting molten steel in a mold, then permitting the ingot to cool in said mold until it becomes self-sustaining, then placing the same in position to be operated upon by a stripping-machine, then forcibly driving a relatively small steel bar or rod through he top crust of the ingot and into the molten interior of the ingot. thereby filling or rep enishing the interior of the ingot,

initially small but inerting solid column of denser steel upon the am; of the ingot. thus forming from and within the ingot a body that is substantially -:.,eX -:;-n. -ive with and which prevents the formation of the usual pipe or cavity, then immediately stripping the ingot, and then reheating the same, substantially as described.

3. The herein-describedimprovementin the art of manufacturing steel ingots, that c-i-usists in pouring the stci-l inta mold, then cooling or permit ing the metal c l until the ingot is rr-mly "o be re; owed from its mo d, then forcibly driving a relatively small steel bar or rod through he end cru. of the ingot and thereby occupying the axial portion of the ingot, thus, first, relieving entrapped and initiating and fcrcing the formation of an gases, second, filling the shrinkage-cavity, In testimony whereof I have hereunto set and, third, initiating and forcing the fornnimy hand, this 11th day of May, 1903, at Chition of an initially small but increasing solid I cago, Illinois, in the presence of two Witnesses. IO central column of denser lnctzilfroi'n and Within ROBERT W. HUNT.

the ingot mass, then immediately stripping WVitnesses:

the ingot and then reheating the ingot, sub- C. G. HAWLEY,

stantially as described. JOHN H. GARNSEY.

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