US729281A - Process of making steel castings. - Google Patents

Description

110.729,281. n PATENTED MAY 26, 1903.

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PROCESS 0E MAKING STEEL CASTINGS. i

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UNITED,

STATES' IIatent-edlyfay 26,' '1903,

WILLIAM E. COYAN, OF HOMESTEAD, PENNSYLVANIA.

PROCESS OF MAKENG'STEEL CASTINGS.

SPECIFICATION forming part of Letters Patent N o. I729,281, dated May 26, 1903.

Application filed January 17, 1903. Serial No.

To @ZZ whom it Wtcty concern:

Be it known that I, WILLIAM E. COYAN, a citizen of the United States, residing at Homestead, in the county of Allegheny and State of Pennsylvania, have invented new and use-I ful Improvements in Processes ot' Making,v

Steel Castings, of which the following is a specification.

My invention relates to an improved process for reducing .the porosity, crystal l-ine structure, and brittlen'e'ss of .steel castings and reducing internal strains therein, thereby greatly strengthening them and improving their durability. l

I have illustrated my invention as applied to the forming of castings'for rolls; but it is equally well adapted for many other articles.

Many attempts havebeen made to increase the strength and life of cast-steel rolls, and of the methods devised the most important is the process of rst casting-the rolls and then annealing them by rst letting them cool and then slowly reheating them from fortyeight to seventy-two hours, thereby bringing them up to atemperature of about 9250- centigrade, after which the furnace isbanked and the temperature held constant for about the length of time employed in reheating. This treatment gives good results, but adds greatly to the cost of the rolls. To obtain equally good results at a decreased cost is an object of my invention.

The simple and novel method devised for accomplishing the object above set forth is fully described and claimed in this specification and illustrated in the accompanying drawings, forming a part thereof, in'which- Figure I is a vertical longitudinal section of a mold with acooling-pipe mounted therein and containing a casting. Fig. 2 is a transverse section of the same.

The numeral l designates a mold for casting a hollow'roll, and mounted in said'mold to serve as a core and also as a means for internally chilling the casting is a pipe 2, surrounded by an eXte-rnaljacket-S; of asbestos or othernon-infiammable and high-fusing material. The pipe 2 extends throughout the length of themold I and is provided with unions 4 on its free ends to enable it to be coupled at one end to a pipe 5, communicatingwithsome source of cooling mediurn,either 139,446. (No specimens.)

liquid or gaseous,.andat the other end to a Waste-pipe 6. Y

In casting a roll'the cooling medium, generally cold water, is first V permitted to run through the pipe 2 to thoroughly cool it and the jacket 3 thereon. The molten metal is then poured into the mold I to form a casting 7, surrounding the pipe 2. The water'is allowed to continue running through the pipe 2 until'the part surrounding the pipe and adjacent to it becomes sufflcientlycool to stand alone, after which the pipe 2 is uncoupled from the pipes 5 and 6 and withdrawn and a stream-'of the cooling medium played into the resulting aperture in the casting 7 made by the pipe 2. The stream is continued until the center of the casting 7 becomes chilled; but the outer portion still retains sufficient heat to reheat the chilled portion after the stream is discontinued.l To give a more definite idea asto the temperatures employed, it may be stated thatimmediately after casting the roll the temperatureof the whole mass is uniform and approximately 1200o centigrade.

By the chilling processthe temperature of the center portion of the roll surrounding the core is then reduced to about 7 00 centigrade, v

when the cooling is fdis'continued. The eX- cess of heat of the outside portion of the roll over the center will vthen reheat the center until the whole mass again attains a substantiallyuniform temperature in the neighborhood of 900 to 925 centig'rade, when the coolingproceeds uninterrupted. Shouldthe'coolingbefcontinued until the casting 7 is completely cooled, I find that the resulting product would be too brittle; but the stopping of the cooling while heat enough remains in the outer portion of the casting to reh'eatthe interior produces the annealing eiect so much desired and decreases'the internal strains,

besides reducing the crystalline structurel and porosity of the resulting roll, and therefore the brittleness. Y l

While I have mentioned water as the cooling medium employed, I may use any of the well-known liquids orgases commonly used for chilling steel, such 'as brine, oil',l compressed air, &c.

Many of the results of my method may be attained by an abbreviated method which consists in using a mold having a core-pipe IOC mounted therein having no jacket thereon, then starting the flow of cooling medium through the core before pouring in any ofthe molten metal, then pouring in the molten metal while the tiow continues, and continuing the flow of cooling medium until the interior of the casting has. become chilled, but heat enough remains in the outer portions ot the castings to reheat the interior.`

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The process of forming steel castings to increase their tenacity and reduce their porosity, which consists in mounting a pipe in a mold, then running a cooling medium through said pipe, then pouring molten metal into said mold and permitting the running of the cooling medium until the casting is cold enough to stand alone, then withdrawing said pipe, then playing a stream of said cooling medium into the resulting aperture in the casting to cool the interior of the casting, and then discontinuing said stream to permit the heat in the outer portion of the casting to reheat the cooled inner portion, substantially as described.

2. The process of forming steel castings, which consists in forming a mold for a casting and mounting a pipe in said mold to serve as a core, then pouring molten metal into said mold to surround said pipe, then running a cooling medium through said pipe until said casting will stand alone after said pipe has been withdrawn, then withdrawing said pipe, then playing a stream of cooling medium into the resulting aperture until the adjacent portion of said casting has become cool but heat enough remains in the casting to reheat said cooled portion, substantially as described.

3. The process of forming steel castings which consists in mounting a pipe in a mold for forming a casting, said pipe being protected by suitable means to keep it from being burned up by the molten metal, then running molten metal into said mold and around said pipe, then running a cooling medium through said pipe until said casting will stand alone, then withdrawing said pipe and playing a stream of cooling medium into the resulting aperture until the adjacent portion of the casting has become cooled, but the outer portion still remains hot, and then discontinuing said stream to permit the remaining heat in said casting to reheat said cooled portion, substantially as'and for the purpose set forth.

4e. Amethod offorlningasteel casting,which consists in providing a mold for said casting having a hollow core therein, then pouring molten steel into said mold to surround said core, and then passing a cooling medium through said core until the adjacent parts of the casting have been cooled but the exterior parts still retain heat enough to reheat said cooled portion, then stopping the passage of said cooling medium to permit the chilled portion to be reheated several hundred degrees by the excess of heat in the exterior of the casting to reduce the porosity of the resulting roll, substantially as described.

5. A method of formingsteel castings which consists in providing a mold fora casting with a hollow core located centrally therein, then pouring molten metal into said mold, then passing a cooling medium through said core until the casting will stand alone, and then removing said Acore and playing a stream of cooling medium in the resulting aperture to cool the adjacent part-s but leave the outer portion hot, then discontinuing the playing of said stream and permitting the excess of heat in the exterior portion of the casting to reheat the chilled interior to reduce the porosity of the casting, substantially as described.

6. The method of forming steel castings, which consists in providing a mold having a core therein, pouring molten metal into said mold and permitting it to cool until said casting will stand alone, and then removing said core and playing a stream of cooling medium into the resulting aperture to cool the interior of said casting but not the exterior which retains heat enough to draw the temper of the cooled interior portion, substantially as described.

7. Amethodofforming steel castings,which consists in providing a mold for said casting IOO with a hollow core, then starting the Aflow of a cooling medium through said core, then pouring the molten metal into said mold while the tlow of cooling medium continues, and continuing the flow of the cooling medium until the center of the casting has become chilled but heat enough remains in the exterior portion to reheat the interior, then discontinuing the flow ot' said cooling medium to permit the chilled portion to be reheated by the excess of heat in the exterior portion to produce an annealing ellect and decrease the porosity and strains in the resulting casting, substantially as and for the purpose set forth.

8. A method of forming castings, which consists in providing the mold therefor with a non-communicating internal hollow metal core of a temperature below that of the surrounding mold, then pouring the molten metal in the mold to surround said core, then maintaining a low temperature in said core by passing a cooling medium therethrough to reduce the temperature of the casting thereof to a greater degree than that of the exterior of said casting, and then discontinuing the flow of the cooling medium to permit the heat at the exterior to gradually extend to and raise the temperature of that part surrounding the core, substantially as described.

9. A method of forming castings, which consists in providing a mold therefor, with a noncommunicating internal hollow metal core the temperature of which is maintained at a low IIO at that part surrounding the core, substan- 1o tially as described.

In testimony whereof I have hereunto set my hand in presence of two subscribing witnesses.

WILLIAM E. COYAN. Witnesses:

WM. H. C. SMITH, J. OLYDE. MILLER.

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