US2458084A - Heat-treating system - Google Patents

Description

Jan. 4, 1949. J. M. LEE 2,458,084

HEAT TREATING SYSTEM Original Filed Dec. 9, 1941 5 Sheets-Sheet 2 Jan. 4, 1949. J, E

1 HEAT TREATING SYSTEM Original Filed D90. 9, 1941 a Z w a ,2 m B m x v a J o MN.)

Jan. 4, 1949. J, M; LEE 2,458,084

HEAT TREATING SYSTEM Original Filed Dec. 9, 1941 5 Sheets-Sheet 4 Jan. 4, 1949. J. M. LEE 2,458,084

HEAT TREATING SYSTEM Original Filed Dec. 9,1941 5 Sheets-Sheet 5 Book GPEIX/NCF mLvEs 7 h 240 k 268 of5 fi 2G5 J 2q ans:

:35? l A r 808 24'? 4on5 32d Joel 4 r" 32/ 54?! nwwmrlc d 336 242" z: LVE

' J27 van-far "i Jflax-Lee Patented Jan. 4, i949 HEAT-TREATING SYSTEM' Jess Max Lce,Los Angeles, Calif. 3;

Original applicationtDecember 9, 1941, Serial No. 422,214. Divided and this application August 17, 1945, Serial N0. 510,917 In i I 6 Claims; (elf Zeae) My invention has reference to heat treating systems or" a type wherein metals aresequentially heated and quenched. The objects and purposes of my invention will appear from What follovvs.

In its present typical and preferredform my .5;

invention has been developed specifically'witha' view to heat treatment of aluminum alloys, such as are extensively used in aircraft construction. The invention will be typ'icallyand illustratively described particularly as applied to the treatment Ill ofsuch alloys; butthe invention is limited thereto. l s i l r l Past; experience and practice in the heat treat ment of aluminum alloys indicates that best re sults, including maximum resistance to corrosion and best grain. structure andxstrengthjareob tained when the alloy is. completely quenched within a period five seconds removalrfrom the high temperature zone The alloy (in the form of sheets, shapes, etc.) is first heateduto a tem perature of around 950? F. to 105095; (depending on the alloy) and maintained at that temperature; fora length of time which depends upon the thickness or mass of the piece or pieces,: and is then quenched quickly. l The quenching operation is usually performed by removing the? parts from the heat treating furnace or: oven and quickly immersingthem in water. Practicewindicatesthat, for best results, not more .thanap proximately five. seconds should interVeneYbe-W tween removal from the furnace and final attain ment of a specified low temperature. (The-A'rmy and Navy respectively specify-that the'quenchingl Water shall be kept below temperatures of 150 F. and 100 F.; that is, that thetemperature of the alloy articles shall be brought "to approximately those maximum water temperatures ithin the quenching period.) The quenching. operation thus necessarilyrequires rather fast movement of the alloy articles, At the high temperatures to which the alloyds initially heated, the metals are comparatively soft and have little physical strength; .Particu-J larly in the treatment of thin sheets and plates, the impact forces generated by fast immersion in the body of Water is very likely to warpland distort the articles; and that distortion is very, difiicult to remove satisfactorily after the articles have been quenched; in. some cases impossible It is one of the general purposes of my invene notnecessarily tion to provide a heath-eating system and ap af,

ratus inwhich metal articlesof any size, shape and mass may be expeditiously removediromihe heating furnace and 3 quickly T immersed and quenched, and comp t ce l ae etie ngdm tliija the indicated time limit. with the minimum amount of distortion.

C ne. of'the primary objects of the inventionis to car y out the. complete:quenchingoperation in a very short; period; and that objective entails the objects ofqattaining fast movement of the load of metal from the furnace into the quenchice bath, and of rapidheat transferin the ,bath. And in connection with .those objectives it is also a general object to provide an apparatus and a method wherein the sequencesof operations can easily be standardized and wherein a, certain amount oi automatic control makes standardization comparatively easyfioi attainment. Itqis consequently one of my general objects, and a corresponding accomplishment of the invention. that the system is easily capable of standardized operation. l i 1. j

, Otherlgeneral. objectives of the invention are the provision of apparatus which is relatively simple, and compact, occupiesa minimum. floor. space, has. low maintenance requirements. All; thcse and further purposes and objects will be best understood from the following descriptions.. l Q H t V g 1 x o t, The features ot the system and, apparatus which laccomplish these. purposes will be best understood irom the following. detailed and specific description of an illustrative fornrof the invention. ;I may however preliminarily mention that, .niongotherfeatures which, will appear, my

invention is characterized by provisions for fast removal: of the loadwof metal from the furnace andmovement into the body of quenching Water or other fluid with a slowingdown of movement at the point of entry; and also characterized by the application of water to the load for a short period just prior to entry into the .body of Water. A Theseiprovisions give the metal greater strength and rigidity by the time it enters the water loody,materially reduce the forces generated. by ater impact andenable the complete quenching of the metal ithin. the indicated time limit vvithminiinurndistortion. i l

J This application isfiled as a division of ray application fier. No. $2,214, which was filed on De cen ber 9, 19 11, and which was grantedonAugust 2i, int gr te; 'No. amazes. The claims r said patent are'di rectedto the structure of the elevatonand its, platform Which carries, the load into the-iurnace and. the quenching bath, and to the. cooperative furnace door, structure whiclraccommodates and passes the platform. structure.

This present divisional application is directed o ce ain,- Qt-he e uree pti y t m. re at n 3 among other things to the attainment of rapid heat transfer in the quenching bath by bouncing the load in the bath, to cooperation of the prequenching spray with the action of the furnace doors and the cooperation of the latter with the elevator.

In connection with the following illustrative description I refer to the accompanying drawings in which:

Fig. 1 is a vertical central section of the complete apparatus, with certain parts shown in elevation, the sections and elevations being as indi cated by line ll on Fig. 2. This figure shows the load-carrying elevator in its floor level position;

Fig. 2 is an enlarged fragmentary-section taken as indicated by line 2-2 on Fig. 1, but with the load-carrying elevator in its lowermost position;

. Fig. 3 is an enlarged view partly in vertical section and partly in elevation, the elevation being 4 taken as indicated by line -3'3on Fig.2 and the section as indicated by line 30,--3a on Fig. :2. In this figure the load carr'ying elevator is in uppermost position with the load in the furnace;

Fig. 41s an enlarged horizontal plan of lower parts of the apparatus, taken as indicated by line.

4-4 onlFig. 1;

Fig. 5 isw-an enlarged detail elevation and section takenas indicated on line 55 of Fig. 4';

. Fig. 6 is an enlarged horizontal section on line 66 of Fig. 5; but showing the traveler I73, I as if in a position below line 5-6;

Fig. '7 is a diagrammatic section taken as indicated by line 1-4 on Fig. 6;

Fig. 8 is a diagram of the electrical parts of th operating and controlling system;

Fig. 9 is an enlarged detail section taken as indicated by line 99 on Fig. 4 with the elevator locked in its uppermost position as shown in Figs. 3a'n'd4.

The furnacefior oven chamber designated generally by the nu'meralZ'O is supported on a suitable supporting structure which includes columns 2'! and horizontal beams 22. Incorporated in the structure of the furnace and its support are two horizontal door supporting rails (channels or similar structural members) 23 which extend along'lower opposite exterior edges of the furnace structure and act as supports and guiding rails for the "two horizontally movable doors 24 which close the otherwise open lower end of the furnace chamber. In Fig. l the section is taken in a vertical plane which lieslongitudinally of the movement of the doors; In that figure the doors are shown closed, meeting each other at their inneredges at 24a, and their opening movements are outwardly in the direction indicated by the arrows. The two doors are hung at each of their endson rails 23 through the medium of roller hangers 26. Their inner edge faces 240, which meet when the doors are closed, are provided each with a plurality of registering semi-cylindric notches 2417 which accommodate certain loadsupporting columns of the elevator when the elevator is supporting the load within the furnace and the doors are closed. The mechanism for'moving the doors will be described presently, after I first'give a brief description of an upper wall into thecenter of which the air duct 4| opens from the circulation blower 42. The box-like structure has lower walls or panels 43 and longitudinal partitions 44 which enclose two longitudinal air ducts 45. These ducts 45 are in communication with air channels 34 through the openings at 4-5. Openings are controlled by dampers 4], adjustable through the medium of vdamperrods :43. Blower 42 takes air from ducts 45 through an air intake 49 which has openings communicating with ducts 45. (The small localized section within the break line indicated A in F le. iShZOWSEflmOHlHlMIliCELtiOIIDf Mmith Q5. :The dotted'l-in'es labeled .43 in 'indicaite the positions of .ith'e communication openings.)

The flower wall "43 of the sloox-dike structure,

between the two longitudinal partitions 44, is

open 'exceptfor the adjustable :louvers350. These louvers, preferably of. sheet metal and of the sectional shapes indicated .inFig. 2, extend transverselzy :across the opening in the bottom -o'f the box-like structure and are adjustably .slidab'le longitudinalzlyrof the furnace iniguides-fii which support their ends. They are arranged innit/erla-pping pairs; :and idle pairs .may be slidably :ad-

justed so that (adjusted gaps :are 'left b'etween -the pairs todistribute the heated air which is :circulated-downwardly lby blower 42. Byad'justi-ng the louvers-t'he hot :air can be direct'e'dand tributedso ast'oobtain even Iheatingand even temperatures throughout any .load. Thermocouples may be distributed .in the furnace and the loadato facilitate the obtaining of :even'tem peratures :by "louver adjustment. And of-course automatic temperature controls may be used to keep .the cheated-air at any: selected temperature. I will'be understood from what hasb'een said, the circulation of air takes place upwardly through passages 34 over heated elements 35, thence through ducts 45 andthe intakeflil tothe blower :42, :thence downwardly from the blower through '41 and distributively through the adjusted louvers. The heated air flowing d'ownwartdly from the louvers is distributed evenly uponzand through the load, and thence the air passes againto zthe'bottom of channel 34 through openings 33a-near-the lower edge of partitions -33.

The load lof metal which is 'being heat treated is irepresented diagrammatically at "-L. The load is v usuallry carried upon a suitable truck (not specifically illustrated) 'and the diagrammatic showing at L merely illustrates the' spacewhich the load and the truck may occupy. The wheels of "such a' truck are indic a-tedin Fig. *3 at 60. The truckshcommon'ly have three "or more pairsof such wheels, symmetrically spaced lengthwise under the truck. And the elevator platform which I will subsequently describe is, among other things, especially designed to .carry 'such a miilti-Wheled truck. In the subsequent detailed description of the elevator I specifically describe "a platform 'designedfor a six-wheeled truck; but'that is intended to be typical of any multi-wheeled arrangement.

I revert now-to themechanism for moving the doors 24. Fig.3 shows, in full lines, the closed position -o'f"t'h'e "doors'as d'oesalso Fig. 1. "Fig.1

. shows; the positions of the truck: is standing at thefloor level F and the cloors are closed. This is thepositionof the parts" either just before the load is lifted into the furnace chamber, orjjust after the load has moved out: of the furnace chamber to the floor level. Fig. 3, in full lines, shows the positions of the parts when vtheload is in the furnace chamher and the doors are closed.

At one end of rails 23 there is a transverse shaft 65 which carries at each end a sprocket 66. (Only one of these sprockets is shown; butthe door moving arrangement at the other end of shaft 65 is the same as shown in 3 and now described.) A sprocket chain 61 is trained (over each. sprocket 66. One end of each chain secured at B8 to a bracket 69 which is attached to one of the doors 24-#the left-handdoor in Fig. 3. The other end of each .sprocketchain 61 has arod extension H3 which isattached at H to a bracket 12 mounted on the other door.24.{ -:.At the other ends ofrails 23 there are two sprockets 14 mounted. on cross shaft 15; and over each of these sprockets a chain 16 is turned, one. end of each chainbeing secured at T! to a bra-cket'lfi mounted upon' the right hand door, and the other end of the chain, extended by rod 19, being connected at. 80. with a bracket 81 mounted .on the left hand door. The arrangement is? such that rotation of shaft will cause canal and opposite translation of the two doors, keeping them at all times parallel to themselves. a The power medium which is applied to move the doorsmay be any suitable medium. But, for reasons which will hereinafter appear, I prefer to utilize compressed air for operating the elevator: of my system, and consequentlyfind it preferable to also utilize compressed air for operating the doors. Accordingly I show a door operating ucylinder 85 and piston 86.

Piston rod 81 is connected with the gear rack 88 which meshes with a gear 89 on shaft65, so that vertical movement of piston 86 will rotate shaft 65 to move the doors in and out. The cylinder is suitably supported in any manner, shown as supported on a framework 90 mounted on one of the rails 23. .In the arrangement as shown, downward movement of pistonflfi opens the doors to the positions indicated in dotted lines in Fig; 3, while upward piston movement closes the doors to their full line positions. Operation of the piston is controlled by in1et and exhaustvalves arranged in pairs. Fig. 3 is not intended to illustrate the actual physical arrangem'ent of the valves, butillustrates the valve and piping connections diagrammatically merely for clarity of illustration. Thus, I i show diagrammatically a pipe 9l connecting into the upper end of the cylinder and having two breaches, an inlet pipe 92 and an exhaust pipe 93;Inlet pipe 92 is controlled by avalve I94 which will be hereinafter referred to as the upper inlet valve. Exhaust pipe 93 is controlled by a valve which will be ref-erred to as the d pper exhaust valve. Another pipe 95 connects into the lower end of cylinder 85 and its inlet and exhaust branches 95 and!" are controlled respectively by the lower inlet valve 1- 98 and the lower exhaust valve E98. The twoinlet pipes 92 and 96 are diagrammatically shown as joining a common pressure supply pipe99 which leads from any suitable source of air pressure, conveniently the common source fromwhich air pressure is obtained' for operating the other parts ofthecompleteapparatus. The fourvalves (as 5-.

parts when the loaded 3 proaching their open positions.

are. all theother control valveswhibh alfirferred to: hereinafter) are assumed to be of a type-normally closed'by a spring and opened only when relectrical energy is supplied to their solenoids lflfl.i Operation-'ofthe doors to open orclose, as may be, is effected by supplyingelectrical energy simultaneously to the upper inlet valved-+94 and the lower exhaust valve E-98, or simultaneously to the upper exhaust valve E-f-SM anduthe lower inlet valve E98.

A four pole single throw switch is'mounted on one of the rails 23' in a suitable position to be operated by anioperating lug IOI mounted on one of -the'doors when the doors are in crap- This switch i-{i is of a type which'is normally open and which is'closed by engagement of lug l0! with its operating 'arm 102p This occurs when lug llJl moves to the left in Fig. 3. Lu'g I01 moves under switch arm I02 and throws it to its dotted line position just as door 24 reaches its open position.

Fig. 8-indicates'howrthe switchwillbe closed when'fi'such movement occ'urs. As will later appear, this 'is one of the controlling switches of the control system; Another switch p, single throw doublep'ole; and of a type normally open, is mounted in such a positionas to' be actuated to clo'sedposition by the lug IOI when the door 24 has moved to the right to its closed position. The 'controlfunctionsvof these two switches will be explainedlater. Switch 10 is of the same physical type-as switch i+7'; see Figs.'3 and 8.

Furnace chamber 20 issupported on columns 2| at a sufficient height above 'floor line F to accommodate the *truck andloa'd L, supported at the floor line, with reasonable"clearance under doors. Zt 'IFhe relative positions are shown in Fig i1; In thisyposition the truck with its load may berblled off the floor ontothe elevator, and viceversa. i A quenching. pit \I I0 isformed in any suitable manner below the floor line and centrally under furnace: chamber 20. The depth of this pit may bewarie'dy it is only necessary that the pit be deep enough. to contain a body of quenching fluid deep enough to completely submerge the load when :it'is lowered to the bottom of the pit and of sufficient volume to have no excessive temperatur 'rise' when quenching 'a maximumload.

l The pit may be made larger or deeper for the purpose yer accommodating a larger body of quenching fluid if..that isxfound desirable in order :tokeep the maximum fiuidtemperature belowithe prescribed .li'n'iitf On the other hand, as willbe :well understo'od,fluid maybe constantly flowed through the pit intorder to keep the temperature from? risingabov'e the 'limit. In the drawings water is shown-in the pit to' the level indicatedW. L. in Figure 2.

Iwill'co'r'nmonly' refer to Water as the quenchin'g fluid but'without intendingto limit myself to'"its useLNIn 'thevariety of uses ofwhich my system' is: capable, various quenching fluids may be used. I Thus,for heat treating dilferent metals the quenching fluid may be either water, or oil or: other liquids, or even cooled gases, such as refrigerated air. And what Ihere say about the quenchinghbath is also true of the cooling sprays. subsequently described; the spray fluid may be whatever liquid 'or "gas best suits the partiular operationbeiriig carried on; although there also T' referto use of waterastypical. Y Extending downwardly from the bottom of pit l-fll piov'ide a vertical elevator cylinder I II. The walls- I I2 of the pit m'ay typically be of concrete and the bottom of the pit'may be termed with a floor recess H3 toaccommodate the packing gland l M and to form shoulders 45 on=whieh the elevator carriage may rest when f-ullydowered. Through and below the lowermost parts or -the concrete Work a downwardcas'ing II G may he extended, with the elevator cylinder 1- 11 containedwithin it. Elevator "plunger has-a shouldered head 1 l8 on its lower 'BH'fi -WhlOh PI'Gf erably engages with cylinder head sleeve l l9-to form a positive step to the upward movement of the elevator plunger and of the elevator as a whole, thus to positionithe :elevator carriage and platform and the load accurately Within zfurnace chamber 20.

Use of avertical elevator of ith'e hydraulic ram type, in and belowthe quenching pit directly under the furnace, isone of the features of :my system which greatly. simplifies the stmlcture and operation of the apparatus and conserves floor space.

Fig 1 shows an air pipe 150 which extends down from the door level :and enters cylinder ill .at its upperiend'. Thesvalves :Eorcontrollih the flow or" :airthrough this pipe varel'oot shownin Fig. l but are diagrammatically :shown in .4. Fig. 4 is not intended to show the actual physical placement of the valves, but onlyrtheir ;functional relation to air pipe ifill. EIn'rthe actual apparatus these valves, as well :as thevalves whichlcontrol operations of doors'2tl, :m'ayhe mounted int-some suitable remote location;.as 'on :a valve panel.

As shown diagrammatically in Fig. 4 two intake valves I'l i and I. l5,2 :areconnectedin parallel relationbetween air :pipe 158 :and air supply'pipe Hi3. Valve 1-45! has a relatively large aperture.

and will be referred teas-the large .inlet valve,

while valve 1-452 has .a relatively small aperture and will be referred :toasxithe .small :inlet :valve; Also connected to air pipe I50, in parallel relationship, are a large .exhaust=valve;E-ll5:l anda small exhaust valve -E.-..Ei'52. Thexspeedzatwhich air under pressureis introduced into theelevator cylinder, or exhausted from :it, depends upon whether the large or the small inlet or' exhaust valves are opened, or both the large randwsma'll; Further, the main air pressure supply "pipezmay' be'provided with .:a manuallysettablowalve 15,5 and. the exhaust pipe I59 may beequipped mvi'tha similar manual valve :1 '50 that the .speed of elevator operation maybe, additionally, regulated in a general Way byqthe setting ofvthese valves. hereinbefore described; that is, theyare normally spring closed and are opened whenzsuppliedawith suitable electrical energy.

In Fig. 2 a pipe 158 is indicated'commumcat ing with the lower end of cylinder-J14. Therfigr ure also shows diagrammaticallythat this extends to the floor level and is ;-oontr0llable ibya manual valve I59. to facilitate blowing off any excess liquid which may accumulate in the lower end :of'thevcylinder by condensation or otherwise; It'IIIlflYEBfl-SO berused for introducing .and maintaining anyupredetermined amount of liquid, such as :oil :or' water or both, in the. lower end ofthe cylinder "rso tass'sito effectively vary the air capacity 10f the mylinder. As will appear afterwards, I ma/y Wish to room trollably adjust the elastic compression and ex-- pansion characteristics of the air .in-.the cylinder, so as to adjust the length and the time period of the vibratory stroke which the piston may gothrough when supported by the elastic body of air under certainaconditions. When the The valves. are all of .the same .type as One purpose \of "this pipe elevator is lowered toward {its hottom -=pos-itloriboth exhaust valves arenormally open. Shortly before "the bottom is reached, the "large exhaust valve -is-closed. 'l he'momentum of -the elevator compresses-the remaining body of :air in thecylinder, and the elevator bounoes. lln bouncing it may-reopen and then again close the large exhaust valve; but anycaseit -hounces untilthe water in the quenching pit lamps the elevator .111. At eachend of longitudinal ibearn 112i there is .a transverse ihorizontally extending mlate l 2] whose vertical width :is equal to the-height .of

beam I26. Di-agonalhraces 112B :aresecuredto beam 1.26, and their :outer ends are secured to spacer .iblocks '1 29 which are allso secured to 'ithe outer :ends of plates 1.21. All of the rparits so tar -.descr;i-bed may be welded :or -othenwise suitably isecured together. mounted :on .pins J3] supported 'ibe'tween the spaced ends of plates fl2'l and'lbhdCBSflZfi. f-.lhese guide rollers :may he of any suitable :and lmown for instance they'mayhe in the former interconnected gears -:and the vertical .ral'ls 5H5 may have racks .with which the :gears rmesh :to prevent the elevator carriage firom tipping when unsymmetrically loaded. The carriage frame-also carries operating pins 13:2 and .il32a for certain corrtrollingsswitches which are mounted .on ."two of the ,four vertical lrails IBIS-which formagu-ides for thecarriagerollers. Of these switchespthe one which is 'shereinaiter identified :as :is mountedoon one of the vertical rails $35 to be actuated '-'by :pin A32; and the ones hereinafter.

identified as ,11 and :are :mounted :on another verticalrail ito beaaotuatedhy the vpin 3132a. naturesiand functions :of these switches :willhe hereinafter described.

locking the elevator with its platform 401' rack at the floor-level, in the position shown iniEig. A. These latter docking rlugs are somewhat below the .fioor level-at the level of the elevator carriage frameinliig. 1.

.Slidablealocking bolts Ma -are mounted in auiding brackets M1! on each of the end plates J21 and iare extended and retracted bymanual to rotation of pivoted :arms 14.2 1mounted-.on.a;shaf-t M3 which extends the length of the carriage f-rameso that both pivoted arms M2 =-may simultaneously rotated. Links |:44.. connect arms I 42 with bolts- 1:41]. .At one :end 510i shaft "1 4-3 sanothersimilar arm 1-4-5 (ore .adisk) is'mounted, and this .armhas sockets M6 adapted togzreceive a dear for "themanual rotation of ssh-aft il .43. :By manipulation {of the parts, it will valoe,rread-ilyrunaGruide rollers 13-0 tare derstood how locking bolts I40 may be projected into the apertured lockinglugs I31 or 131a or retracted from them. The socketed part I45 is somewhat below the floor line when the elevator islocked in the position of Fig. 1 at the floor level, but the sockets may readily be reached with an operating bar. Alternatively, any suitable known means of remote operation may be applied to the locking bolts. I I

Automatic means are later described for keeping the elevator and its load supported by adequate air pressure at all times, and for automatically maintaining the elevator and load in their proper uppermost positions when the load is in the furnace in the position of Fig. 3. The positive locking means are provided as safety devices to hold the elevator and load in either of the two described positions in case there should be failure of the operating air pressure, and also to hold the elevator rigid at the floor level position while loads are bein transferred to and from the elevator. It'is desirable that the arrangement be such that the positive locking means cannot be released unless the elevator and load are adequately supported by the fluid pressure, in order to preclude the possibility of uncontrolled descent of the elevator and load. Ordinarily, the frictional engagement of locking bars I40 with looking lugs I31 under the downward pressure of the unsupportedelevator and load will be sufficientto either make it impossible for the locking bars to be manually retracted, or at least to make that retraction sufficiently difficult to give the operator a definite indication that the elevator and load arenot fully supported by the air pressure. This action may be enhanced by providing rough or corrugated surfaces of engagement between the locking bars and locking lugs; or it may be made positive by providing small notches in the lower edges of locking bars I40, the notches being adapted to hook over the lower edges I31b of the apertures in locking lugs I31 if the elevator and load are not fully supported by the fluid pressure. See Fig. 9.

For purposes which will appear, I do not mount the load-carrying truck directly upon the elevator carriage frame, but upon a platform which is removably mounted upon that carriage frame in such a manner that the platform is the only part of the elevator structure to be subjected to the furnace heat, and so that the platform may be easily removed and replaced in case it should deteriorate under the heat. The preferred form of structure is shown in the drawings. The platform includes two longitudinal rail beams I60, preferably composed of channel irons and supported on three spaced pairs of transverse supporting plates or bars I6I and I62. I show three, to accommodate a truck with three pairs of wheels; the number of course will vary, three are to be taken only as typical. All of these pairs of bars are welded at their centers to the upper ends of tubes I63 which telescopically fit down over three vertical posts I64 which are mounted and secured at their lower ends, as by welding, to the central longitudinal beamlZB of the carriage frame. Cap disks I65 are welded to the upper ends of tubes I63 and rest on the upper ends of posts I64 to carry the load thrust. The outer ends of the central bar pair I62 are-welded as indicated at I66 to the rail beams I60. The outer ends ofth other two pairs of supporting bars IBI merely extend underthe rail beams I60 but are not weldedto them. This arrangement allows longitudinal expansion and contraction of rails I60 without warping the structure. The longitudinal spacing of the pairs of supporting bars I6I, I62, are such that the wheels 60 of the load-carrying truck, when on rails I60, will come directly over the transverse supporting bars. The load weight is thus not carried on rails I60 at points inter mediate the rail supports, andthus the structure is protected against distortion which might otherwise be due to the weight forces when the platform is at elevated temperature.

When the elevator and load are in the position shown in Fig. 3 and the doors closed, the door edge notches 24b accomodate the columnar supports of the elevator platform. In this position the platform has a substantial vertical clearance above the doors and the carriage I has clearance below the doors. The platform clearance over the doors is somewhat more than the amount of elevator movement required to 1 actuate the automatic controls which keep the I elevator fully supported in its uppermost position. That control is described later.

With the load in the furnace, the only part of the elevator that is in the furnace is the platform. All other elevator parts are outside the furnace where they are not subject to heat deterioration. The platform itself is of small mass; consequently little heat is wasted in heating the elevator--the no pay load in the furnace is a minimum.

y I have described how certain of the elevator control switches are mounted on vertical guide rails I35 at or near their upper ends. These switches are the ones which, in the control system, control the elevator movements at or near the upper end of its travel, and for that reason are preferably mounted on the guide rails. Other switches which are now to be described and which control the lower movements of the elevator are not conveniently mountable upon the uide rails as' they would thus be close to or under the water level in the pit. For such reasons a vertical switch carrying panel I10 is provided adjacent one of the vertical guide rails I35 (the guide rail shown at the upper left in Fig. 4). The body of this panel is made up of two channel-shaped members HI, and longitudinal T-beams I12 Within the space between members HI, and

guided by them, is a vertically movable traveler I13 which carries two protruding sw itch actuat ing pins I14 and which hasa cable sheave I15 mounted upon it. A cable. I16 is secured at one end at I11 to the upper part of the switch panel and extends down and under sheave I 15 and then upwardly to pass overa sheave I 18 and thence over another-sheave I19 and thence downw:ardly, as shown at I16a in Fig. 5 to be secured to some part of the elevator carriage frame. Fig. 4 shows Zhow the end of the cable may be secured, at I 161) to the switch actuating pin I32 a which is carried Sheaves I18 and I19 may be mounted on a brace plate I which is secured.

on the carriage frame.

to the upper end of guide rail I35 and to the upper end of the switchpanel. The whole arrangement is such that traveler I13 and its switch actuating pins I14 move vertically along the switch panel through distances equal to one half the elevator travel. Theswitch panel may thus be materially shorter than the length of the elevator travel; the lower end of the switch panel may be accommodated in awen I 6|. H The two 'T-rail-sfl12 form mounting rails for the various switches.- The structureof: the whole aabaose switch panel may of course be variedwidely but as shown in :the drawings the twochannel-shaped membersi-ll are spaoedly secured together by rectangular frames I35 which surround and are. secured-to members I'll at spaced levels. T-ra-ils tl-Ze. are securedto the outer faces of the rcctan gular frames I85. so that the rails are somewhat spaced from member ll't, as shown in. Fig. 6. Switch mounting clamps are are mounted upon the rails in such a. manneras is shown in Fig. 6 and are. adjustable t any selected vertical position, and settable in the. selected positions by tightening the clamps. These clamps carry brackets.- It'l upon which the several switches are mounted, and the switches are thus very accurately adjustable as totheir vertical; positions. Typicalpositionsof the. switches are shown Fig. 5.

The. uppermost one of these. switches, the one: which is actuated when. the: elevator isv nearest. the bottom of its travel, is the switch labeledh.

This switch is located, in effect, a short distance above the bottom of elevator travel, say about 24 inches above the bottom. This switch it is of the two-pole, single-throw,.snap-over type, as indicated diagrammatically in Fig. 8.

Proceeding. in downward orderon the switch panel but in upward order with reference to. elevator travel, the next switch on the panel is the one labeled g,- which is actuated when. the elevator is-iust a shortdistance below. its floor. line positionthe elevator position shown in Fig. 1. This switch g-; is of the two-pole, doublePth-row,

snap-over type,.as indicated diagrammatically in.

Fig. 8.

Next. in downward. order on the switch panel, and upward order. with reference to elevator travel, are. the two. switches which are labeled re.-

spectively aand ee. Thesetwo switchesarein. effect. located substantially, at the floor level- Switch. a. is a. two-pole-single-circuit switch er a type which is normally closedandwhich. is.te1nporarily opened by movement of its switch. arm in either direction. The diagram of, the-switch. in;

Fig. 8 indicates its made of operation It. is. temporarily opened by the elevator movementat the floor l'evel'when one of the switchactuating. pins in wilpesby its roller i3! on its-actuating arm Hill. in either direction. Figsfi and 7 Show the typical relation. of the pins. l'tfd' to the. switch arms.

Fig- 7 showing typical relation ofp ini'll l, travelli'ng, along line Ella, to the actuating arms of.

switchesa-and f.

Next in downward order on the switch panel and upward order on the elevator movement. is a readily understood how the arms: and rollers pro-.

trude into. the vertical travel path of actuating. pins. PM so that the pins, by their up and down travel... either wipe by the actuating arms to.tem.=

porarily actuate. such a switch as. a, or to snap the operating arm of such a switch as e e from one position tothe other. The-arm structure of. switch. is. typical of. all the switches-of snap-overtypehereimdescribed. i

Ill

Fig. '7, which is an enlarged section taken on. li-neL-T of Fig. 6, shows the relation of typical switches a. and f"tofone of the switch operating pins l'M. The pin travels along the. dotd'ash linel'Ma. Operating arm I99 and rol-ler: HM of the single threw-switch a are shown in normal (switchclosed) position. The dotted lines showthe two positions to which the arm is thrown. to open the switch as pin I'M wipes by the roller in either direction. Ihe double operating arm ESL-L93 of the. typical snap-over switch. f is shown infull lines in one of its positions. be snapped over to thedotted line position by upward travel of pin I'M (downward travel of the elevator) and then back again to the full line positionv by downward travel of the pin,

Switches d, ee', g, h, and is are all snap-over switc hes'of. the same general physical nature as switch I and are operated in the same manner,

u either by one of the pins il l on the switch panel by one of the pins 332, 232a on the'el-evato-r" carriage. Some of these switches are doublethrow, some. single-throw, as shown in Fig. 8. Switch b-c (mountedat the top of a guide rail I35 and actuated by pin $32). is of a physical nature similanto switches zq' and m. It is nor.- mally held in one position to close the switch 19,. as. indicated in Fig. 8; that is, it is normally open as regards the switch c. Actuating pin i452 moves vertically past roller HIE-b on the end of its operatingarm 582d. The arm normally stands at such an angle- (see Fig. 8) that pin I32 wiping by in either direction will throw the switch bladetemporarily to close. switch 0 and open b. As soon x aspin I32 haspassed the switch goes back to normalposition with 0 open and b closed.

Spray pipes 29d are shown in positions spaced around the. space occupied by load L when it is at floor level position as shown in Fig. l. The placement and positions of the spray pipes as here shown are merely typical; they may be placed and mounted in any manner around or over the loader: as tothoroughly spray the load with coldwater or other cooling fluid as the load moves down toward the water bath. An electric: ally operated. control valve 2t! controls water supply to the spray distribution pipes 2622. Switch p; controls. valve. 26 i The general. sequence of operations will now be explained, followed by an explanation of the control system which afiects the sequences.

. At the start of a heat-treating sequence the elevator is atthe fioor level as shown in Fig. 1; preferably locked: imposition by the positive locking: bars tall, but. also supported by air pressure in the elevator cylinder. A. previously treated load has been removed. withthe elevator in that position. A. truclrloaded with a fresh batch of metal to be treated is rolled. onto the elevator platform and made. fast. in any suitable manner. Locking bars Hill are then withdrawn, doors 2% areopened, and air pressure admitted to the elevator cylinder to move the elevator up until the elevator platform and the loadare completely within the furnace chamber above the. level of the. doors. Fig. 3. The-doors are then closed, theload brought up to. the required temperature, and maintained atthattemperature for the desired length of time. When the doors close they are moved into tight sealingengagement with the lower edges of the furnace. walls. The door carryingrollers 26 roll upon. small wedgeszfia as the doors reach closed. positions=,,moving the doors .up against sealing. gaskets. 2612" (see. Figs. 2 and 3) While: the: load is in the. furnace the elevator is It will See.

supported in its upper position by air pressure, preferably maintained automatically as will be described. The elevator may also be positively locked in that position, as a safety measure to prevent the load weight from being imposed on the doors in case the air pressure should fail for any reason. Also, in long continued beatings the air pressure and the automatic controls may be shut off if desired, for conservation of energy. In any case, however, the elevator cannot be un locked (or at least readily unlocked) for lowering unless the air pressure fully supports it and the load.

When high temperature treatment is completed the elevator is unlocked and the doors opened. Air pressure is then exhausted fromthe elevator cylinder to lower the load. As soon. as the load clears the doors they are againclosed. The doors are normally kept closed to conserve furnace heat, only being opened temporarily for passage of .the load in and out. In the presentdesign door closure occurs as the lowering elevator nears its floor level position (Fig. 1). The clearance of the load under ,the doors atifloor levelposition may be made to be as large as desired, although it is preferred to keep it restricted so as to minimize the distance that the load has to travel between the furnace, and the water bath and so as to minimize the necessary. speed of that travel.

As the load approaches the floor level position and just before entering the water bath, its speed is momentarily checked andthe sprays are turned on. The exact sequence of those two operations is not significant. It is desirable that the load be sprayed, before entering the Water, sufficiently to sharply lowers its temperature and increase the strength of the metal before striking the Water. But it is preferred to close the doors before starting the water spray, to prevent spray entering the furnace. Checking the speed of the load just before entering thewater has the effect of decreasing theimpact forces but of course lengthens the time period elapsing between load emergence from the furnace and. entry into the water. While some pre-entry hesitation of the load may be had Without preventing full quenching of the load within the prescribed timelimit solely in the water bath, the preliminary spraying is advantageous because it starts the quenching operation immediately after emergence from the furnace and thus not only strengthens the metal to withstand the water impact but also facilitates the travel hesitation because the time required in the water bath to complete, quenching is thus reduced. The preliminary cooling caused by spraye ing also facilitates the maintenance of the water bath at any required low temperaturenless heat having to be absorbed by the bath.

As hereinafter explained, the spraying continues' until the load is submerged. The hesita tion. in travel takes place just before load entry into the bath,and after the load strikes the water at reduced speed it then moves on downward at what would be full speed except for the water resistance. Near the bottom of the elevator travel the downward speed is again checked by closing the larger one of the elevator-cylinder exhaust valves. Momentum of the elevator and load causesthe load to bounce on the air cushion in. the elevator cylinder, and in bouncing it may repeatedly open and close the large exhaust valve, until release ofthe pressure through the smaller exhaust valve lets the elevator gradually settle to .the bottom on the floor shoulders-U5.

- proper vertical locations with relation to elevator travel; Figs. 2 and 5 show the relative vertical locations of theswitches. However Fig. 8 shows each 'individual elevator-actuated switch in the vertical orientation it would assume if the switch wereactuated directly by the elevator movement rather than by a member which moves oppositely to the elevator. And in the following part of the description, I refer to switch movements as up or down, having reference to the orientations of Fig. 8 and reference to movements of the switch blades. -In Figl 8 switches of the snap-over type (whether single or double throw) are diagrammatically shown with two operating arms, as for instance the two operating arms I92, i913 shown for switch f. Switch-esof the type which are normally closed or open in one position and are operated'only temporarily'to the other position are shown witha single operating arm and ro1ler'jas arm [90 and roller Hill of switch a, or arm (02d and roller IMbof switch 19-0, or the roller da rryihg arm 102 of "switch i-j or p. Fig. 8 shows" all theswitches in the positions assumed when the'elevator is resting on bottom.

Starting with the elevator on bottom, the operator movesthe raise button 250 in the direction indicated by the arrow in Fig. 8 to close the raising circuit which leads from power supply line 240 through 24 8,then' through the auto maticf button 242 thence through 243, 244, the raise button 250, and thence through 215! and 252 through the normally closed switch a, and thn'cl through 253 and 254 through the actuating coil 25st: the small intakevalve I-l52, and thence-through 256 and 251 to power lead 253. Attliistime switch 79 is closed to close a parallel circuitTifl, 260, 26l to energize solenoid 262 of the large intake valve I--i5l The elevator then movesupwardly and during this upward movement it first closes switch h (which is located say about24 from the bottom ofthe elevator travel) and then, just before the elevator reaches its floor level position (Fjig, 1)it throws switch g to. afpo'sition opposite to k that shown in Fig. 8. Those two switches are in the lowering control cireuitwhich is only operative when either one of the (loweringfbuttons are closed. The effect of actuationof these two switches during upward travel 9f the elevator is merelyto leave them both in their positions efiect-ive for-the subsequent lowering Operation of the elevator. ,ljNext, askthe= elevator movesupwardly, switch a ing both the intake valves, and the elevator comestoa stop at its floor level position, with switch a still held open. Switch :1 is located in such a pqsition, and the physical engagement of operating pin ,I'H with its operating roller till is o fi suflicient vertical extent to allow the elevatorto to astop before switch a is allowed to close againlnfthis position the elevator may be assume 1 physically locked. and-the-loaded truck. run onto it. The loaded; elevator cannot now be moved. further upwardly until furnace doors. 24 are opened. When these doors arefully opened they" close the switch: iY-j-i Switch parallels switch; a by reason of the connections 215:, 2-16: Closing switchi thus again completes the raising. circuit. The furnace doorsare normally closed: as the elevator movesupivardly into its. floor level'position.. To open the doors the operator closes-the open button 2% which. closes the door open ing circuit which leads from power leads 240 through 2%, the open button, and, through 281, 2138.,- switch 2),. 218-9, and thence in parallel through winding-.219 of lower exhaust valve- E- 98, and winding Zl i' of upper intake valve 1-94, and thence through 212. to the other power lead 253. As result, piston 86 of the door operating. mechanism is moved. downwardly to Open the doors.

At the end of the door opening; movement, switch actuating lug; Ill-I (see Fig. 3) engages the roller on operating arm H12 of switch 1 -7 to close, that switch and hold-itclosed. as long as the doors remain open. Switchis in parallel with switch a, by connections 21-5 and 216, so that the'closing of switch 2 again closes the raising circuit ofv raising button 250, which was broken by the opening of switch a; Consequently the subsequent closure of the raising button again energizes boththe large and small intake valves I l'5l and 1-452. of the elevator to introduce air under pressure to the elevator to cause further. upward movement,

In passing, it shouldv be-noted that about the same time thatswitch, a is opened by the. elevator arriving at the floor level, or at least at a time before the. elevator moves its loadupbetween the furnace doors, the switch e-e' is thrown to. a position opposite to. that shown in Fig- 8 (down, in that figure.) The general function of, switch c has to do with the automatic lowering operation of the elevator, which. will be: describedlater. The general function of switch e isto prevent closing of the furnace doors at any time while the load is between the doors. The action. of these switches, as well as of switch d w-ill presently be described. The switch e--e is. locatedon the switch panel I'Hl' (see Fig. 5) at substantially what correspondsto the floor level. positionot the elevator. 7

As the elevator moves up fromthe. floor level position, switch I, which is located on switch panel HQ in eiiect just above the elevator floor level position, is thrown down to a position oppositeto that shown in Fig. 8; This switch, like switch it and g, has only to do with the lowering operations.

As the elevator proceeds on upwardly, and at a distance of say about 12 inches from its uppermost position, switch 7c (mounted on one of. the guide rails I35, seeFig. 5') is snapped down to a. position. opposite to that shown in; Fig. 8,.and thus opened. Switch is controls the individual. circuit of winding. 2-62 of the large intake: valve 1-451. The large intakevalve thus closes as the elevator approaches its uppermost position, leaving only the small intake valve Il512 open, and the elevator slows down.

Finally, as the elevator reaches 'or approaches closely to the top. of its movement, switch :1 (also located: on one of'the guide rails |35--'see' Fig. 53* is snapped over to. a position opposite to that shown in Fig. 8". As'wil'lbe explained, switch (2 has to, do-wit-h-thea door closing circuit, and its movement to the laststated position enables the door: closing circuit to be operated. That circuit was broken when: switch e was thrown down; at the floor level position, and is nowrremadeby; switch cl being thrown down.

Also, at about the same time that switch 11 is snapped over, andjustas the elevator approaches its final uppermost position, the switch 'b=-CT is transiently-operated; to throw it to position op positeto that: shown in- Fig. 8.=as the actuating pin l-3zwipesipastiit. In the uppermostelevator position the pin has passed above the roller ,lllil'li onswitclr arm? lfiza'. This switch h--c is of the typewhichihas anormal spring actuated position which is shown in Fig; 8.. If the elevator moves do-wn'azshort distance, its operating'pin; l 32 moves down into operative re-engagement with the arm roller of the switch and again opens switch b'andcl oses switch c; The function of this switch,

as later: explained, is. to automatically feed air under'pressure into the elevator cylinder to keep the elevator supported in its. uppermost position. Thev door closing circuits and functions of switches e-e' and: (it will now be explained.

The'circuittwhi'ch effects and control's'the closoperation of: the doors is as follows: Close button Z8ilis connected atone side by'28'l to a contact 282 which is connected through raise button" 25ll"wi:th' contact 283 when the raise button is-"in normal position-open as regards the-previouslydescribed raising circuit. The last named contact 283 is-connected by 28s to 243 which is connected through the automatic button and 24-I withpower lead 2%. (The purpose of this circuiti'ng of the cl'ose-and the raise button is tomake them ineffective whenever the automatic lowering button is 'used to lower the elevator.) The other side of close switch 288 is connected by 235 and 2'86'with one of the upper pair of contacts of switch d, and by 281 with one of the lower pair of contacts of that switch: The other upper contact is connected by 288*with one of the upper pair of contacts of switch e and theother lower contact of'switchd isconnected by 2 89F with one of the lower pair of contacts of switch e. The other upper contact are and theother lower contact of that switch are both connected by 298', 29E with both the energizing coils 292 and 296 of the upper exhaust val-veE-M-and the lower inlet valve L98 of the door operating mechanism, the two coils being connected in parallel between 2% and 212 which leads to the other" power lead 258. The circuiting arrangement is such that the described door closing circuit cannot be energizedunless the switchese" and d areboth in their upper or both in their lower positions; With the two switch blades inirelatively opposite'positions no circuit can be. established because 288' is in circuit only whenaboth switches. are up and 289m circuit only when. both switches are down. As has been stated-,. switch .3 has been snapped down when. the elevator passed its floor level position, while switch d was still. up. Thus, until switch 1 is thrown down when the elevator reaches its upper.- most position, the door closing circuit cannot be closed to energize valve coils 282, 293 to operate the door mechanism to close the doors. i But as soon as'the elevator, or close to its uppermost position, snaps switch'a, down then the doors can be closed.

As stated before, the elevator is stopped mechanically at the upper end of its tra'velby engagement of plunger shoulder H8 with the lower end of sleeve 9. The operator keeps raise button 282 closed until the elevator reaches its upper position, and then, or any time just before, closes the door close button 280 until the doors close. be mechanically locked in its upper position for safety. i

Switch 12-0 is a two-pole double throw switch normally held in its upper position (in Fig. 8) by its spring. In that position it puts the opening button 265 in circuit to be effective to open the furnace doors. As the switch operating pin I32 (see Fig. 4) moves up with the elevator approaching uppermost position, the lug wipes by roller I022) of the switch, momentarily reversing it but allowing it to move again to normal position (Fig. 8) when the elevator reaches top position.

The doors are at this time open, so the temporary breaking of the opening circuit at switch b is of no eifect. The temporary closing of switch is neither of any effect because its two contacts are connected by 300 and 301 in parallel with the raising button 250 whichis at this time'supposed to be closed. (If the operator should release the raising button 250 just before the elevator reaches the top, the closed switch 0, in parallel with the raising button, will cause the elevator to move on to its uppermost position.) However, after the raising button is opened then if the elevator sinks by reasons of air leakage, the operating pin I32 wipes down ontoswitch roller l02b and again throws the switch down (Fig. 8). This occurs before the elevator has sunk far enough to let the elevator platform contact the doors. Closing of switch 0 closes the previously described raising circuit tofeed air to the elevator to raise it until ,the switch is allowed to go back to normal position (Fig. 8). The elevator and its load are thus automatically kept at uppermost position if the elevator is not mechanically locked. And if it is mechanically locked, the elevator is constantly fully supported bythe air pressure so that it will not drop when unlocked. And while switch b is open (whenever the elevatonhas sunk) the door opening circuit controlled by that switch cannot be closed to open the doors. This provision makes certain that the doors cannot be opened when there is any liability of the elevator load being upon them.

When the elevator and load are to be lowered, it is first necessary to open the furnace doors and mechanically unlock the elevator. For reasons The elevator may then which have been stated, neither of these opera tions can be performed unless the elevator and load are fully supported in their upper positions. And, as will be seen,.in: one of the modes of control operation the elevator cannot be then lowered until the furnace doors are fully opened.

When the furnace doors are opened, switch z'-a' is thrown to closed position and held there until the doors subsequently start their closing movement. The function of switch 1' in conjunction with switch a has been explained. Switch 7' when closed energizes a relay to close certain relay switches which have control functions in the circuits which control the automatic lowering operation of the elevator-an operation in which the lowering necessarily automatically follows door opening. In manual operation of the systemthe doors are opened as pre viously explained. In that mode of operation the elevator must remain in its upper position in order to open the doors due to thecontrol of switch b on the door openingcircuit; but manual 18 control is depended on to not start the lowering of the elevator until the doors are fully open.

Manually controlled lowering of the elevator is controlled by either or, both the lowering buttons 305 and 306, The circuit for button 305 is from lead 240 through 301 to the button, thence through 308 and 309 to and through the set of switches f and g, and thence through 3I0, coil 3 of the large exhaust valve E-l5|, and 3l2, switch It and 3I3, 26! and 25'l to the other lead 258. The lowering button 305 thus controlsthe large exhaust valve E-l 5|, subject to the controls of switches f, and h. .Switch h is always closed except when the elevator is near the bottom of its travel. Switches 1 and g were left in their position opposite to that of Fig 8(snapped down) when the elevator passed the floor line. position on its previous movement up. The. circuit through 1 and g at the time now under consideration is as follows: from 309 through the lower contacts of switch 1, thence through 3l5, the lower contacts of switch 9 to 310.

The circuit for lowering button 306 is from lead 240 through 320, the button, thence through 321, winding 322 of small exhaust valve E-l52, and thence through 323, 26l and 251 to the other lead 258. The small exhaust valve will remain open. as long as lowering button 306 is held closed, being subject to no other manual control.

If lowering button 305 is closed the large exhaust valve EI5| opens and the elevator moves down until switch 1 is snapped over (up in Fig. 8) just above the floor line position. Switch 1 now being in its upper position, the circuit through f and g is broken and the elevator may stop before it reaches switch g at a position just below the floor line. However if at this time, or previously, the operator has closed button 306 to open small exhaust valve El52, the elevator will proceed on downwardly, but at slowed pace until it reaches switch 9 to snap it over to its upper position (Fig. 8). The circuit to the large exhaust valve is then re-established through switches f and g as follows: from 309 through .325, the upper contacts of switch 1, then through 326, the upper contacts of switch g, and 321 to 310. The opening of the large exhaust valve begins to accelerate the elevator in its downward motion at just about the time the loaded truck L enters the water. The load consequently strikes the water at low speed, but is increasingly accelerated as it enters, so that the load is quickly submerged and quenched. The relative degree of retard, or hesitation of movement, as the load approaches the water depends on several factors, such. as the distance between the two switches and g and the sizes of the two exhaust valves, all of which maybe adjustably changed.

Just as the elevator starts down switch d is reversed to its upper position in. Fig. 8. With switch 6' still in itslower position the door closing circuit is broken, making it impossible to close the furnace doors until the elevator reaches the floor level position where it reverses switch e back to its upper position. The doors may then be closed by closing the button 280 either at that time or previously. The door closing circuit is then the same as before stated except that it extends through the switches d and e as follows: from 285, through 286, upper contacts of switch d, 288, upper contacts of switch e, to 290.

Incidentally, switch 0 is momentarily closed immediately after the elevator starts down and has the momentary effect of energizing the raising control circuit. But at that time switch It is 1 9 open-and disables the-large jintake valved-I51"; so that the closing of only opens the's mallintake valve I-l52;- The large, exhaust valve E-iSl', if not both exhaust valves, being open, the-elevator continues'down'i Shortly afterwards the switch 7c is thrown back to its closedposition;

- A-lso incidentally the switch a is momentarily openedas the elevator passes the floor level position, but its opening is ineffective as the circult of the raising-button 250% open at that time. Switcnaiunctions' only to stop the elevator at the floorlevel on its wayup, v

Asthe'elevator approaches its bottom position switch it is again opened; breaking the circuit of the large'exhaust valve El-I51. The'closure of that valveat abouttwo' feet above bottom, produces the bounceand agitation before eX- plained. The elevator then settles to the bottom Withthesmall exhaust valve open The operator then releascsthe' lowering button or buttons. The vpartsofthe control circuit are then all in the positions '-=initiallydescribed and'shown in Fig. 8. The next operation is to raise the quenched" load as previously described.

InFigQB' theeriergizing coil 3360f spray valve 29! isshown as connected across leads 2% and 2358", byconnectors "332- and 333, in series v with spray button 33 I; In lowering the elevator under manual control, thefoperaton applies the spray duringt-he slow travel of" the heated load, before and" as theload "enters-the water bath? Automatic operationo'f thespray will be explained after the automatic lowering operation has been" described.

The electrically controlled 1 operations when the automatic button-"2421s used for lowering the elevator will now-be described: 'At the beginning of these operationsthe elevator is-in uppermost position and the doors are'closed; The several switches are in the same positions" before described: the positionsto which they are thrown by the-upwardtravelof the elevatorto its uppermost position.

Theautomaticbutton" 242- in itsnormal or open position closes the' circuits 24%, Z43; 244, 23 3-" and Zo'tWVhich-connect the raising button 250 and the door closingq'button' 289" to power lead" 2 AM; In the operated-or closed position of auto-- matic' button fidg-thesei-cirouits are broken, so that the'manual closing button and raising button cannot be used"simultaneously-with the automatic'button: 1

When the automatic "button lsfCs6d, circuit'is established fiorn lead Ni through 335; the button, SZiEvfthe' two lowercontacts, off switch e (which is thenfdow'n)", 337; 258; switch'b' (which must be closedto'completethe circuit), 269, door operating valve coils 270' and 27 i and 21 2* to the lead 258: The doors thenopen, provided the elevator is'clear up and switch 22 is closed. The door operating valiles remain open until their circuit is broken when switch a is thrown up asthe elevatolr passes the-floor level. V p

"When the doors arefully open,- switch 'i -y" closes and establishes a-circuit from button 242; through 3%, switch 7'; 3411 relay magnet 342-; and* 3- 43 to 25? and lead-258i There layswitbhes m; it; and 0, close. Relay switch m closes-a self-f holding-Circuit-S'M"(between 3M and'3 l0) in par'- allel with switch 7' to hold the" relay closed afterswitch 7' opens 'andias long asfthe' automatic-but ton m2 isheld closed j (It ish d closed until" the elevator reachesf'bot tom)1 1 Switch 12- closes a circuit 24 I',

switch n$ 34?if -to conductor 321; in parallel with the} manual-lowering button 306. Closure of switch" it (with-2 42 closed)- consequently opens the srnall exhaust valve Iii-i52 by the same circuit cont rol as has been explained for button 306;

' Switch 0 closesa circuit from lead z iitthroughscribed; and=switeh ii and 'the bounce'near the bottom; are operated 'in the same manner. After the elevatorsettlestdthe bottom the automatic button is released and all the switc'hes are then again in the positionsof'Fig; 8.

During the downward movement before reaching: the flo'or level switches b--c, d'and-lc are operated inthe same m'anner as in the manual oper ation and with thesameeffects; At the floor level switch e--e" issnappedoverfto its upper position (Fig. 8) as before described; but itnow has the automatic function'of causing door closure without 1 closingbutton 280 being manually operated. VV-henthe automatic button 252 is originally closed it establishesthe circuit through 336, switch e (then downin-Fig. 8), 331,- and switch b (then down)" to open-the fiirnace doors; This has'sbeen described; This circuit -isfinally broken when switchi'ee" is thrownito the upper position at thefloor levehpositionofthe elevator; and then switclie automatically establishes a door closing circuit as" foll'owsr- With: button 242' closed the circuitgoe's fro'm33$,through350, the upper contactsotswitch e;- wh, 286, the upper contacts of switchidl ithen up), 288*, upper contacts of swit n='e} 2911;the coilsiziliiiliiiiiof thevalvcs which effect door closure): andiithence" through 2?; to 163131325851 Intthis operation the automatic switch eactsainitheseicircuits iniparallelwith the manual closing buttonzziiii ancit-thus.ieffects the same functions' as that button',. but: automatically.

Automatic operation ofa the: spraying system is such as to beginsprayingi'at about' the time the loadaapproaches orrreaches the floor level, and to continue: sprayingfuntili'theirload is submerged. As'sth-eecloors. closes'substantiallyat: the time desired forsspray inceptionamt because it may be undesirable to startthe:sprayi'untilithev doors are closed'ionnearly'olosed,'I may control the spray inithe .manneitnow described.

1 Switch p;of thei'sameimechanicalitype asswitch 1-7, is mountedcin'suchiia position on" thefranie oflfurnac'eras to;be closed'by the-switch operating vator, relay switch m is closedwhen the doors are fully opened? The elevat'or'the n starts down, as described and the doors then automatically close; Asthey closejth'e circuit through switch p I is closed, swit'cnm remaining closed as long as Closure lug- .lfiimountediqom door: 24;; when. the doors 21 completely submerged. The spray thus operates in a general way coincidently with the slow travel of the load. After the load submerges, the spray is of course ineffective; but in the illustrated control system it is finally shut off when button 242 is released and relay switch m opens.

Many changes and variations may be made in the described apparatus and methods, within the scope of my invention as defined in the following claims. In the claims as well as in the description I use the term bath without any limitation to requirement of a solid body of fiuid; it may be as well a heavy spray or shower. In other words the bath in which the heated load is submerged may be either a bath of solid fluid or may be a spray or shower bath.

I claim:

1. In a system for heat treating metal articles including in combination a heating furnace having a closure at its lower side, means for opening and closing said closure, a quenching bath spaced below said furnace, a fluid pressure cylinder located below the quenching bath, a lift plunger extending upwardly from the cylinder through the quenching bath, a load receiving platform carried by the upper end of the plunger, plunger operating means including a valve control mechanism for admitting and exhausting pressure gas into and from said cylinder, said mechanism comprising valvular means automatically actuated by movement of the load receiving platform for restricting the exhaust from the cylinder during downward movement of the plunger when the load receiving platform is at a predetermined point of its downward travel in the quenching bath so as to form a gaseous cushion upon which the plunger and load receiving platform oscillate in the bath.

2. In a system for heat treating metal articles including in combination a heating furnace having a closure at its lower side, means for opening and closing said closure, a quenching bath spaced below said lfurnace, a fiuid pressure cylinder located below the quenching bath, a lift plunger extending upwardly from the cylinder through the quenching bath, a load receiving platform carried by the upper end of the plunger, plunger operating means including a valve control mechanism for admitting and exhausting pressure gas into and from said cylinder, said mechanism including a first valve means, a second valve means, means actuated by said second valve means for restricting the exhaust from the cylinder during downward movement of the plunger when the load receiving platform is .at a predetermined point of its downward travel in the quenching bath so as to form a gaseous cushion upon which 22 the plunger and load receiving platform oscillate in the bath.

3. The improved system for heat treating metal articles as specified in claim 1, further characterized by spaced switch means actuated by the load receiving platform, a spray system adapted to spray the load when the latter is in a position below the furnace closure, and spray actuating means automatically actuated by one of said switch means that is responsive to the downward movement of the load receiving platform and responsive to the closing of the furnace closure.

4. The improved system for heat treating metal articles as specified in claim 1 further characterterized by including a mechanical lock on the load receiving platform and adapted to support the platform, said lock being non-releasable when a substantial part of the load weight is being borne by it.

5. The improved system for heat treating metal articles as specified in claim 1 further characterized by including locking means in association with the platform to maintain the same in position above the furnace closure, and means for preventing opening of the furnace closure except wh n the platform is maintained out of contact with the furnace closure.

6. The improved system for heat treating metal articles as specified in claim 1 further characterized by including valvular means controlled by the position of the load receiving platform and acting automatically to circulate fluid pressure to the cylinder to maintain the platform in a position above the furnace closure, and means for preventing opening of the furnace closure except when the platform is maintained out of contact with said furnace closure.

JESS MAX LEE REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,173,590 Lichter Feb. 29, 1916 1,298,682 Fay Apr. 1, 1919 1,388,575 Kenworthy Aug. 23, 1921 1,959,215 Owen May 15, 1934 2,263,029 Buckner Nov. 18, 1941 2,265,849 Marsh Dec. 9, 1941 2,341,766 Fox Feb. 15, 1944 2,383,203 Lee Aug 21, 1945 OTHER REFERENCES Aero Digest, pages 84 and 87, September, 1940.

Images