US2638909A - Quench tank for heat-treating processes - Google Patents

Description

y 1953 w. c. HIATT ET AL 2,638,909

QUENCH TANK FOR HEAT-TREATING PROCESSES Filed Sept. 22,1949 3 Sheets-Sheet 1 INVENTORS WILLIAM c. H|ATT WALTER B. CHENEY PMQ D' y 1953 w. c. HIATT ET AL 2,638,909

QUENCH TANK FOR HEAT-TREATING PROCESSES Filed Sept. 22, 1949 3 Sheets-Sheet 2 IO I2 28 FIGZ.

F I63- INVENTORS WILLIAM CHIATT WALTER B. CHENEY AT T'Y Patented May 19, 1 953 QUENorn'r-ANKimR HEKTQTREATING I moons SE'S Willi'amwfi) i Haven i Hiattcaand Walter ClieneygaNevw mie, assignors: to" International: Hamvester -bompany; aicorporatiolrof lflew aierseyz Applicat'iomseptemlier 22, 1949; Seri'a l.Nb; -1 1 7;I6 1*- Y be definedcasthe introductionof an interruption in -the cooling cycle at thelproper timeit'o permit equalization of temperature withimthesmetalf fore allowing transformation from-austenite to martensite toi begin; The metal when: properly treatedi by thisrprocess shows a finamartensitic; grain structure" with increased hardness which increases-:the durability offth'e material andits resista'ncetoweaii. Inio'rder to properly 'p'erform' tliisiwproce'ss the quenching operatiomi's ofl prime importance; Various typesyofquench tanke have" beemdesigne'dfin order:twperformthe quenciiiiig stepsirof thisprocess; None of these have-satis factori'ly performed a quenching process in a' manner intended. t'oi-faciiitatethe mass or 'prodilc tion quenching of the; parts;- Therefore mar'--- quenching: on amassproductiombasis has here tofore: been found to: be impractical.

In order to secure rapid quenchingvit is-def sir-able to agitate thefifluid within -the quenching" tankzswthat: a" maximum. dissipation o'fzi h'eat -in' th article is accompiished =-witiiin a 'reiwtiveiy' short time cycle. Variousa types-of impellende-- Vices havebeen introduced andconstructedi'to'op crate within the tanks; Theseimpe1Ie1- "devi'ces' were intended to agitate the quenching. fluid? Heretofore devicesof this type have-not provedsatisf'a'ctory since the position of the impeller"- and-the agitation oi the-fiuidwith respect; to -the articles: to be quenched have net -received 'sufd ciently careful consideration. The agit-arti'on-=- produced by these previous impe11eridevices=-iias-- not been sufiicient to produce a quick" dissipation of the heatin the articlesandtherefbrea -uni' form martensitic' structurehas notb'eenobtaijn'ed. Generaliyit was foun'd that austeniteandbainite would appear in the sections and-consequently severeinternal stresses would be set LiIT'in the article's --treated';- These faults are: directiy'ia'" re sult' ofimproper "quenching I where"tiie'* agitation- It is; applicants prime obj ect"therefore 'to'providean improved quench tank that will be efifctive toqu'ench articles inma'ss 'quantities'ir'ra manner 51Glaimsa (Cl. 134*447);

2?: that will. facilitated. thefl. tneatinge process; known asi m arquenching.

Stilli anuthei object isiztozprovide amimproxiedi quenching? tank: having?" strategicallim located? bafiiing means designed to aid in the agitation-i ofithe quenchingrflui-dz AESi'iilLlfllIffihEb-Obj e'ct is to pnovide aamimpmvedi tankzha'vin'gia pluraiity ofiimpellrsi font:agitating: the? quenching fluid-3 the? impellersa being ifosi' tioneda atuaap'oint "below r the articles; U31 quencinad;v thearticle's heing positi'onediin thee direct path: of the": quenching fluid'-as. 1516K? celer-ated and agitated? at a high ve'locityMy.ti'i'e 'eimpellers; i

Iti-iS" a stillf. further" obj ect to provide 1am infproved i quench tank having: impel-lea mean's 'comstructe'di a nd,arranged te agitateand oii'ouiaitm quenching fluidiihi a circularpath -at anelatively high: velocity; thevelo'city ranging norm-armies tiveiiy;flight-acceleration to a pc-int' of low acceler Figure 5' i'sa 1ef-t-- end view inelevation of a quenchtanl'c.

The improvement "is genera-i132 embodied m t-he form of a quench tank designated hy' the refer ence character-- HIE The quencl'i -tarfli Hic'om sists of end walls I I an'd: si-'de-*-wail's supported on a bottom [3. A toppr cover M covers the" tank I E? to'provi'd'e-a substantially-enclosed' cham- IE. The chamber rs is "fluid tiighti-axrd adapted" to contain" a quenching fiiiiwas" best shewnin Figure 1. The--chamber l5 is-"fiii'ed with the quenching'fliiid"to a: pointjilstsiielowzthe' cover?! Iii" Anfxopenihglfisprovideddnt thecover? i=4") the" opening being" arranged to provide. an: access for the entrancezof 'articiesfto hei-treated within"theciiamlceiF5.

A pair of separators or walls I! are substantially centrally positioned within the chamber [5. The separators I1 are horizontally spaced and extend laterally across the width of the tank as best shown in Figures 2 and 3 to divide the chamber I5 into first and second subchambers [5; A passageway i8 is defined by the separators 17, the passageway I8 being substantially in alignment with the opening l6. The passageway I8 is open at its upper end as indi+ cated at I 3 and is provided at its lower end with oppositely disposed inlet throats or openings 20. The inlet openings 20 are formed by a pair of horizontal walls Zlythe walls 2| extending or projecting laterally outwardly from the separators I! as best shown in Figures 1 and 2. The lower end of the passageway I8 is provided with a centrally located baffle 22. The

baffle 22 is positioned to divide the lower end 0f the passageway i8 into separate channels 23. Baffles 24 are located in the channels 23, the bafiies being formed of an arcuate sheet and being arranged to direct fiuid entering into throats upwardly through the passageway |-8.

An elevating device 25 extends through the opening I6 of the tank. The elevating device 25 is provided for the purpose of delivering and removing articles to be treated to and from the passageway [8. This device may be of conventional construction and includes, generally, a vertically extending track through the opening l6'down into the passageway l8. The track 26 is suitably connected to one side 12 of the tank by means of brackets 21 and 28. A channel 29 is slidably secured to the track 26 and a tray or carrier 30 is connected to the channel 29. The channel 29 may be moved in a vertical direction by an elevating mechanism not shown. The tray or carrier 30 is provided with a reticulated or screened platform 3| on which a plurality of articles 32 to be treated may be carried.

A pair of agitating units 34 are symmetrically positioned at opposite ends of the tank In. Each agitating unit includes an electric motor 35 which is rigidly mounted on a support 36 connected to an end wall H of the tank H]. Each motor 35 rotates a shaft 3'! which in turn drives a beltv 38. The belt 38 in turn is arranged to rotate a shaft 39 which is journaled in a bearing-box 40. The bearing box 49 is suitably connected to the top 14 of the tank ID. A sprocket 4| is rotated by the shaft 39, the sprocket in turn being arranged to drive a chain 42 for driving a sprocket 43. The sprocket 43 is positioned within the tank adjacent the bottom [3. A shaft 44 is driven by the sprocket 43, the shaft 44 being journaled in a bearing box 45. Each impeller 45 isdriven by a shaft 44, each impeller being enclosed by a shroud 4'! positioned to direct liquid into each feed throat 20. The motor 35 may be of a variable-speed type orthe belt drives may be so arranged as to rovide for variable speeds in the rotation of the impeller.

V In the operation of the quench tank In articles to be. quenched 32 are removed from a furnace, not shown, and placed upon the reticulated platform 3| of thetray 30. The elevating device 25 is actuated to move the tray 30 into a position within the passageway [8 as best shown in Figure 1. It will be noted that the tray 30 is, in this position, below the upper open end I9 of the passageway. Quenching fluid is present with- 26 which extends 4 in the tank andv each impeller 46 is driven to circulate and force the fluid directly through the passage I8 in a circular path as indicated by the arrows. The fluid is thus constantly in flow and in agitation and the impellers are arranged to direct a high velocity flow through the passageway 18. It must be especially noted that the tray is positioned in the passageway at a point where the rate of the fluid flow is at or near a maximum velocity.

The positionof the baffles is so arranged that the fluid is moved from the impellers 46 in a circular path up through the passageway l3 and down back tothe impellers. At a certain location in this circular path a point is reached where the velocity of the fluid flow (as determined by the pressure exerted by the impeller) is at a minimum, and the subsequent movement of the fluid is occasioned by the natural forces of gravity, molecular cohesion etc., rather than due to the positive impelling force exerted by the impeller. Quench tanks have been designed previously that have contained impellers but all of these have been designed with the primary view of creating a general turbulence and none has taken into consideration the location of the impeller as related to the material to be treated as being significant. The location of the impeller and the velocity of the flow with relation to the articles, in previous devices, was such that an effective martempering could not be attained. In articles hardened in these previous devices the grain structure would be imperfect and this process therefore never reached extensive use.

The general theory covered by applicants novel invention may be also described by the following terminology. The impeller exerts a force against the liquid which may be likened to a pushing force. This pushing force exerts a high acceleration and the fluid under a high velocity courses through and around the articles on the reticulated platform thus dissipating heat from the articles in a quick or rapid manner. The flow of the fluid is in a circular path, and at a point in this path the impeller no longer creates a positive pushing force. The fluid beyond this point, continues to move but the movement is the result of a pulling force which may be considered only as an indirect result of the work of the impeller assisted by natural forces such as gravity etc. It is not however, directly occasioned by the energy expended by the impeller. Applicant has positioned his tray within the passageway l8 so that the articles are brought in contact with the flow of fluid at a point where the impeller is pushing the liquid at a high acceleration and before the velocity has reached a minimum point. As previously indicated in the specification, this novel arrangement is of great significance since it makes possible the mass production of heat treated articles having a fine martensitic grain structure.

It can therefore be seen that the position of the impeller with relation to the carrier is of prime importance. In an effort to secure the rapid dissipation of heat in the articles, applicant has designed a tank including a passageway bafiled in a manner that will facilitate the rapid flow of quenching fluid to the article treated. The novel tank design therefore makes it possible to marquench large quantities of articles in a manner resulting in a properly hardened article.

In the process of marquenching the quenching operation is of prime importance. Applicant has provided a tank that will perform this quenching process in a production manner heretofore not considered possible. It must be understood that a preferred embodiment of the invention has been disclosed and that changes and modifications may be made in the'design and construction without departing from the spirit of the invention nor the scope thereof as defined in the appended claims.

What is claimed is:

1. A device for quenching heated articles comprising a quench tank having a fluid chamber, walls extending vertically within said chamber, said walls defining a passageway open at its upper end for communication with said chamber, said walls having inlet openings adjacent their lower ends, a baflie positioned at the lower end of said passageway arranged to divide the lower end thereof into separate inlet channels, each channel including wall portions projecting outwardly from the passageway into the chamber, an impeller positioned adjacent each inlet channel, each impeller being arranged to impel quench fluid at high velocity from the chamber through said passageway, and an article carrier positioned in said passageway whereby articles to be quenched on the carrier are immersed in the high velocity flow.

2. A device for quenching heated articles comprising a quench tank having a fluid chamber, walls extending vertically within said chamber, said walls defining a passageway open at its upper end for communication with said chamber, a baffle positioned at the lower end of said passageway and extending vertically into a portion of said passageway to divide the lower end of said passageway into separate inlet channels, said walls having inlet openings adjacent their lower ends, an impeller positioned close to each inlet channel, each impeller being arranged to impel quench fluid at high velocity from the chamber into said inlet channels and through said passageway, and an article carrier positioned in said passageway whereby articles to be quenched on the carrier are immersed in the high velocity flow.

3. A device for quenching heated metals comprising a fluid quench tank, a pair of spaced vertically extending separating walls disposed in the tank, said walls providing a vertically extending passageway positioned to divide said tank into first and second fluid chambers, the passageway being open at its upper end to provide a fluid outlet, 2. tray movable in the passageway to a position below the fluid outlet of said passageway, inlet channels positioned at a lower end of said passageway, said channels including walls projecting outwardly of the separating walls and into the first and second chambers, a battle at the lower end of said passageway for dividing the lower end of said passageway into separate passages, the separating walls and said baffle being arranged to direct liquid upwardly through said passageway outwardly through said fluid outlet, means for impelling fluid disposed within the tank, said impelling means being positioned sufliciently close to said inlet channels to impel fluid through said inlet channels and through said passageway at a high velocity, said tray being positioned in said passageway and in the high velocity flow.

4. A device for quenching heated metals comprising a fluid quench tank, a pair of spaced vertically extending separating walls disposed in the tank, said walls providing a vertically extending passageway positioned to divide said tank into first and second fluid chambers, the passageway being open at its upper end to provide a fluid outlet, a tray movable in the passageway to a position below the fluid outlet of said passageway, inlet channels positioned at a lower end of said passageway, said channels including walls projecting outwardly of the separating walls and into the first and second chambers, a first bafiie at the lower end of said passageway for dividing the lower end of said passageway into separate passages, a second baiile in each passage, the separating walls and said baiiles being arranged to direct liquid upwardly through said passageway and outwardly of the fluid outlet, impeller means disposed within the tank, said impeller means being positioned sufliciently close to said inlet channels to impel fluid through said inlet channels and through said passageway at a high velocity, said tray being positioned in said passageway and in the high velocity flow. l

5. A device for quenching heated metals comprising a fluidquench tank, said tank including an opening formed in a top portion thereof, a pair of spaced vertically extending separating walls disposed in the tank, said walls providing a vertically extending passageway positioned to divide said tank into first and second fluid chambers, the passageway being open at its upper end to provide for communication with the fluid chambers, a reticulated tray movable through the opening in said tank and into said passageway to a position below the upper open end of said passageway, inlet channels positioned at the lower end of said passageway, said channels including walls projecting outwardly of the separating walls and into the first and second chambers, a first centrally disposed baflie at the lower end of said passageway for dividing the lower end of said passageway into separate passages,

a second baiile in each passage, the separating References Cited in the file ofthis patent UNITED STATES PATENTS Number Name Date 500,979 Tweedy July 4, 1893 501,347 I Insinger July 11, 1893 646,266 Diescher Mar. 27, 1900 737,079 Chase Aug. 25, 1903 982,578 Dilg Jan. 24, 1911 1,059,845 Delahunty Apr. 22, 1913 1,459,079 Anthony June 19, 1923 2,052,254 Shaver Aug. 25, 1936 2,374,500 Reading Apr. 24, 1945 FOREIGN PATENTS Number Country Date 239,422 Switzerland Jan. 3, 1946 290,182 Great Britain July 4, 1929

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