US2794224A

US2794224A - Method of cooling cast metal preferentially

Info

Publication number: US2794224A
Application number: US359997A
Authority: US
Inventors: Edmund Q Sylvester
Original assignee: Griffin Wheel Co Inc
Current assignee: Griffin Wheel Co Inc
Priority date: 1953-06-08
Filing date: 1953-06-08
Publication date: 1957-06-04
Anticipated expiration: 1974-06-04

Description

June 4, 1957 E. Q. SYLVESTER 2,

METHOD OF COOLING CAST METAL PREFERENTIALLY 2 Sheets-Sheet 1 Filed June 8, 1955 INVENTOR.

June 4, 1957 sYLVEsTER 2,794,224

METHOD OF COOLING CAST METAL PREFERENTIALLY 2 Sheets-Sheet 2 Filed June 8, 1953 Unit ms METHOD oF-oooLu-sooissr-MeTAL PREFERENTIALLY 6 Claims. (Cl; 22- 212) This invention relates to -foundry practice 'and more particularly to a novel method-*and means for eliminating hot tears in castings-of 'metal such' assteel'and'other ferrous metals.

When molten metal such as steel is-p'oured into*a"conventional mold, freezing or solidificationof =th'e metal is initiatedby the formation-of an envelope of solid metal at the mold and metal interface.

If the casting is of simple form,-'the envelope-develops with substantially uniform thickness over thesurface of the entire castingbecause the 'heat of the-molten metal is uniformly dissipated and absorbed by the mold thereby preventingthe development of'-'hot tears.

According =to Lille present invention, however, "'itf has "been discovere'd that the pouring-of annular castings,

such-was wheels-in:- graphite molda alfhou'gh producing-unusually fine castings at low costfifrequently results hot tears because of the big heat-conductivityt$f tlie -graph ite, =a characteristic whichis :reqriisite in the production of castings suitable for use under conditions oe -severe wear-arid shoole as; forexample, railway I car truGk WHeels. in .such molds :a relatively thick envelope" of solid metal is very rapidlyformed throughout the ent iresurface of theccas'ting with theexcep'tion of an' areae or areas fed'bysa riser 'orsrisers. "Consequently,'-af-ter the casting has solidified and the risers have, perEormediheir function of feeding the solidifying castings to-prevent shrinkage -cracks therein, lsol-id contraction progressing -through'theeaentirezzcasting tends to develop hot-' t'ea'rs in "the1arc'as' where the-casting was connected to the rise'rs. :According "to-the present t invention, :it has b'een discovered: fthat tthe development :of f such hot -tears' can be eliminated without sacrificing other -superior charaeter-' istics of such castings This is accomplished by removing the *risers atter thcy have "completed their function of feeding the'solidifying casting and'prior to solid contraction of the casting,

place.

According'to'the'invention, thelcope and risers are renrove'd immediately upon solidification of -th'escasting. .Therea'ftenby means of a novel cooling apparatus, compressed air from a shop'line at a pressure value'ofabout 90 pounds per'ssquare inch is directed against the sprues where the :r-isers were previously.tconnectedatothe casting. This novel process affects an increase in the cooling rate of the metal beneath the surface of the sprues, so that the portions of the envelope in these areas become as thick and strong as the remainderof the surface of the casting prior to solid contraction thereof, whereby upon such contraction hot tearing is eliminated.

Other objects and advantages of the invention will become apparent from a consideration of the following specification and the accompanying drawings, wherein:

Figure l is a central vertical sectional view through a graphite mold and pressure pouring apparatus, prior to pouring of a casting;

Figure 2 is a fragmentary vertical sectional view simiand by,subse, q.uently cooling thev 'r'isersprueson thecas'ting'beforelsuch contraction takes A 2,194,224 lattentecl June 4, 1%57 '2 iar to' Fi'gure -'l but --showi-ng"the-mold removed from the pouring apparatus withthemold cope and" risers removed from the casting and showing the novel sprue cooling apparatus associate'd with the casting;

-Figure 3 is -a planview of' the' sprue cooling apparatus shown in Figure 2;

Figure 4is a-side-elevational viewof one of the sprue cooler units applied to the casting whichis fragmentarily illustratedin cross section, and

ffFi gure 5- is -a-1bottom plan view ofthe sprue cooler-unit shown in Fig'ur-e 4.-

Describing the invention-'in detail and referringfirst-to "Figure 1, -'-a ladle 2 containing a "body of molten metal, such assteel; is disposed tin a=pressure= chamber-*-4"having 5 a sealed= cover '6- and' having: a= conduit '8-' for the passage of a pressure gas such as air.

I 'The cover' 6 '-is provided with -an opening "'10 within which' a pouring tube 12 is sealed; The tubeis provided :at its upper :end externally of the-chamber 4 with- 'a head 14f1seated atthe u1iderside thereof on 'a' tapered gasket "16 i supported by -the-top of the cover -6. Thus-the tube l z'aaud' headMare -maintained in til-ted p'osition,-as=described in detail and claimed in 1 my "copending applica- :tion,:.'-Serial No. 299,071, filed July 16, 1952, nowabandoned, ifomCast-ing Metho'd arid-Apparatus.

The head 14 is provided 'wi'th an'upwardly tapering uconical seat, 18: adapted i to rna'te with a complementary ;seat? 20. defin-ing the rnargin of 'an opening in the' bot- 'stomro'fiaatray or pa'n122 containinga drag -24 of 'a graphrite :mo'ld which: also comprises a cope ZG. l lie cope and drag imay :be %formed "of any -:suitabl 'e-solid refractory *nraterial: machined to define =a -casting=cavity 28. Howrofi graphite; the com-position and themanufactureofwhich -:is set -forth in cdetaib in my copending applioation serial No. 189,961, filed October 13, 1950, for Wheel, Mold,

and Method of Making.

:The:castingacavity:28 is1:connected by-=a{gate 30 to the dipper endco'frthettube 12, ;whereby upon:admission of 40 :zp'ressure gas -to-;the chamber 4 through the conduit 8, =the jrnoltencmetal' in the ladle 2Tis forced upwardly through i the :tube [12 -;and;gate -'30' into the easting: cavity 285 and --.upwardly therefrom into riser cavities 32, defined by ibalcecksandccups: 33 within'zcomplementary operiings of thexcopei26. aOnly one of"the*riser cavities' isillustrated-sin :irFigure F1',YIIOW6VI', it will ,be 2 understood that wpre'ferably three, sand ifvdesired more, of sllbh cavities zmaywbet equidi'stantly spaced from :-each other: around the zperir-neter ref athe'rcastinga cavity 28,: as described in de'tail rti-nvsaid rcopend-ing? application Serial No. 1'89,-9'6 l Thercope 2:6 is aalso1providedwith a= plungerfi l sleeved through a complementary openingaofthe-copeand having vatapered-thead"; or :seat :36 engage'able :withi a complernentaryiseat at :the upper'zend-of the :gate 30 to seal the lat-tenwhenrthe cavities 1-28: and 32. have been fill'ed with imolten-zmetal, whereupon cp'ressurein the chamber '4 is exhaustedd'o accommodate removal: of the graphite: mold and:- assembling :;of "an'otherz mold; on'ltop oft che pouring tube 12,-;pr'eparatory=toapouringsanotherrcasting;

I tllp mrqremovaltofatheagraphite moldifromathe-pouring tube 12 and during a time interval of the order of about five minutes after pouring the metal in the mold freezes to form a casting 38 (Figure 2), which is fed during this period by risers of molten metal in the riser cavities 32. At the end of this time interval the cope 26 is removed. Normally the risers break off and are removed with the cope; however, occasionally one or more of the risers and their associated cups 33 pull loose from the cope as the latter is lifted from the drag, and in this event such risers are immediately broken or cut oil and are removed from the casting 38.

At this time the various sections of the casting are at a as compressed sition each unit 40 as shown in 56 of each chamber 42 direct compressed air against the temperature values of from about 1800 F. to about 2300 F. and substantial solid radial contraction of the casting 38 has not yet taken place. Before substantial contraction does take place and while the sprues are at a temperature value of from about 2100 F. to. about 2300 F., the novel sprue cooling apparatus 39 shown in Figures 2 to 5 is lowered into engagement with the rim of the casting which in the illustrated embodiment is in the form of a railway freight car wheel.

The sprue cooling apparatus 39 comprises three or more cooler units 40, the number of which corresponds to the number of risers utilized. Each unit 40 comprises a tank or chamber 42 connected to a pipe 44. The pipes 44 are in turn connected to a line 46 having a conventional shut ofi valve 48 as illustrated in Figure 2, said line 46 being connected to a supply of compressed gas such air from a shop line at a pressure of the order of about 90 pounds per square inch. The gas may be at or below room temperature.

The underside of each tank 42 is provided with a positioning lug or bracket 50 having converging positioning surfaces 52 and 54, as best seen in Figure 4. The surface 52 is adapted to seat on the upper edge of the rim of the casting 38, and the surface 54 is adapted to engage the outer perimeter or rim of the casting to properly po- Figure 4, so that ports related sprue 58 at a point Where the casting 38 was fed during solidification thereof by one of the risers.

Compressed air is directed in this manner against the sprues 58 fora period of time of the order of approximately one minute to affect an increase in the cooling rate of the metal beneath the surface of the sprues 58 so that the envelope constituting the outer surface of the casting 38 is of substantially uniform strength throughout all portions of the casting, prior to solid contraction thereof, thereby eliminating hot tearing as the casting 38 contracts radially during cooling thereof to room temperature.

I claim:

1. A method of making a ferrous metal casting comprising pouring such metal when molten into a graphite mold having an annular casting cavity partly defined by a cope with a riser cavity communicating with said casting cavity, then after the metal has solidified in said mold to form a casting and a riser connected thereto, and before substantial solid contraction of said casting has occurred, removing the cope and disconnecting the riser from said casting, and then cooling an area on said casting Where said riser has been disconnected from said caststream of compressed gas against said area while the remainder of said casting cools at room temperature, and finally terminating said stream of compressed gas and cooling the entire casting including said area at room temperature.

2. A method of making a metal casting comprising the point where said casting was connected to said riser; then before said contraction has occurred directing a stream of coolant gas against said area while cooling the rest of the casting at a room temperature, and finally terminating flow of said gas against said area and cooling the entire casting including said area at room temperature.

3. A method of making a casting comprising pouring molten metal into a mold having a casting cavity and having a riser cavity communicating with the casting cavity, then after the metal has solidified in said mold, to form a casting and a riser connected thereto, disassembling the mold and disconnecting the riser from said casting to form a spot on said casting at the point where said riser was connected thereto then cooling said spot at a rate substantially in excess of the cooling rate of the remaining surface area of the casting before substantial solid contraction of the castng has occurred, whereby such contraction does not produce a hot tear in the region of tho sprue, and finally cooling the entire casting including said spot at room temperature until the entire casting is at room temperature.

4. A method of making a casting comprising pouring molten material into a mold having a casting cavity and a riser cavity connected thereto, then, after the material has solidified in said cavities, disassembling the mold and disconnecting the riser from the casting, and then before sub- .stantial solid contraction of the casting has occurred, directing a stream of compressed coolant gas against a spot on said casting at the point of interconnection between the riser and the casting, while cooling the remainder of said casting at room temperature, and finally terminating flow of said gas against said spot and cooling the entire casting including said spot at room temperature until the casting reaches room temperature.

5. A method of making a casting comprising pouring moltcn material into a mold having interconnected cast- I ing and riser cavities, then, fied in said cavities, disconnecting the riser from the casting, and then before substantial solid contraction of the after the material has solidicasting has occurred, cooling a spot on said casting formed by the connection thereof to said riser at a rate greater than the cooling rate of the remainder of said casting.

6. Apparatus for cooling hot spots in a wheel casting comprising a plurality of spaced heads, each of which comprises a plurality of ports for directing a coolant gas against its related spot, a surface on each head facing the ports thereof and formed and arranged to engage the tread surface of the wheel casting to position the apparatus relative thereto.

References Cited in the file of this patent UNITED STATES PATENTS 7,515 Truscott July 16, 1850 15,109 Allen June 10, 1856 1,281,946 Grifi'in Oct. 15, 1918 1,969,840 Goddard Aug. 14, 1934 2,032,738 Cramer Mar. 3, 1936 2,117,948 Flammang May 17, 1938 FOREIGN PATENTS 514,598 France Nov. 17, 1920