US2583967A - Furnace lift and translation mechanism - Google Patents

Description

Jan. 29, 1952 L, B, RQSSEAU 2,583,967

FURNACE LIFT AND TRANSLATION MECHANISM Filed July 27, 1948 8 Sheets-Sheet 1 Jan. 29, 1952 B. Rossi-:AU 2,583,967

y FURNCE LIFT AO TRANSLATION MECHNISM Filed July 27, 1948 8 Sheets-Sheet 2 INVENTOR abe @new .l @QM ATTORN EYS Jail 29, 1952 L. B. ROSSEAU FURNACE LIFT AND TRANSLAUON MECHANISM 8 Sheets-Sheet 5 Filed July 27, 1948 R O T N E V m Jan. 29, 1952 8 Sheets-Sheet 4;

Filed July 27, 1948 NVENTOR M556@ ATTORNEYSY Jan. 29, 1952 L, B RQSSEAU 2,583,967

FURNACE LIFT AND TRANSLATION MECHANISM Filed July 27, 1948 8 Sheets-Sheet 5 INVENTOR Jan. 29, 1952 A l., B. ROSSEAU 2,583,967

FURNACE LIFT AND TRANSLATION MECHANISM Filedy July 27, 1948 8 Sheets-Sheet 6 INVENTGR BY @.QI@

ATTORN EYS L. B. RossEAu 2,583,967

URNACE LIFT AND TRANSLATION MECHANISM 8 Sheets-Sheet '7 Jan. 29, 1952 Filed July 27, 1948 Jan. 29, 1952 l.. B. RossEAU FUNNACN LIFT AND TRANSLATION NECNANTSM 8 Sheets-Sheet 8 Filed July 27, 1948 INVENTOR Mea BY en l ATTORNEYS n@ E l Patented Jan. 29, 1952 FURNACE LIFT AND TRANSLATION MEcHANIsM Leon Bidwell Rosseau, Narberth, Pa., assignor to Ajax Electric Company, Inc., Philadelphia, Pa., a corporation of Pennsylvania Application July 27, 1948, Serial No. 40,862

9 Claims. l

The present invention relates to furnace mechunits, especially in pit furnaces such as salt baths.

A purpose of the invention is to economize on furnace space, and on equipment space generally, both horizontal floor space and head room, in mechanized furnaces, especially salt baths.

A further purpose is to simplify and cheapen the mechanism required to transfer work from one furnace to another.

A further purpose is to permit advance of work units at two different rates, one of which may be relatively rapid and the other relatively slow.

A further purpose is to aid in returning work units to an initial position after they have completed the cycle.

A further purpose is to support Work units on rails extending along the top of a furnace or line of furnaces, to push the work units forward along the rails by pusher bars, to raise selected work units, for example at obstructions or at a point where a different rate of advance is required, by

an elevator preferably acting on the work units at either side of the rails, and to transfer the work units in an elevated position suitably along the elevator, from the elevator to a return conveyor or from the return conveyor to the elevator by pusher bars acting in the elevated position.

A further purpose is to employ different rates of advance on pusher bars operating at different levels, and to move work units from one level to another to secure advance at the desired rate.

A further purpose is to employ lifting bars on the elevator which are discontinuous, and preferably to add temporary lifting bars in gaps, where the lifting bars are normally discontinuous.

Further purposes appear in the specification and in the claims.

In the drawings I have chosen to illustrate a few only of the embodiments in which my invention may appear, choosing the forms shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration cf the principles involved.

Figures 1 to 5 are diagrams illustrating steps in the procedure which is followed.

Figure 6 is a side elevation of a furnace mechanism embodying the invention.

Figure '7- is a top plan of Figure 6.

Figure 8 is a front end elevation of Figure 6.

Figure 9 is a sectional perspective of the mechanism of Figures 6 to 8.

Figure 10 is a fragmentary perspective illustrating the elevator in raised position and a pusher baracting on work units in such position.

Figure 11 is a fragmentary sectional perspective of a rail and one of the lower pusher bars.

Figures 12 and 13 are sections of Figure 11 on the lines |2-I2 and |3-I3 respectively.

Figure 14 is a perspective of one of the elevators, showing the insertion of a supplemental lifter bar.

Figure 15 is a circuit diagram.

In the drawings like numerals refer to like parts.

Described in illustration, but not in limitation, and referring to the drawings:

Pit furnaces have been extensively employed for heating of metals and the like, and in recent years have been very widely employed in the form of electrically heated salt bath furnaces, especially of the Hultgren type. The problem of advancing the Work units automatically in such furnaces is, however, relatively difficult, as they do not lend themselves conveniently to roller hearths and other conventional furnace conveyors.

In efforts to solve this problem, comparatively complicated and space-consuming mechanism has been employed, and such equipment has particularly been wasteful of furnace space.

The present invention is concerned primarily with the automatic manipulation of work in pit furnaces, such as electrically heated salt bath furnaces, particularly with a view to obtaining greater simplicity, lower installation cost and maintenance cost, more economy of operation 1 and greater production per unit of furnace space.

In accordance with the present invention, work units are raised and lowered vertically and are acted on by pusher mechanism in both the upper and lower positions, suitably acting at different rates.

The general nature of the invention will be understood by reference to Figures 1 to 5. Considering Figure l, rails 30 extend suitably horlzontally, conveniently at the top of a furnace cf line of furnaces 3l, conveniently located immediately below the space between the rails, and desirably of pit type, so that work can be inserted downwardly into the same.

Supported on the rails are work units 32, suitably extending from rail to rail and. depending into the space or spaces of the furnace or furnaces, as later explained.

When work units are referred to herein it will be understood, as Well known in the art, that these units include work holders, fixtures and work held thereon, although it will be understood that in certain cases the shape of the work may be sufficiently advantageous that it is possible to Vrails at an intermediate point between the beginning and end of the furnace. Aor line ofrfurnaces. Behind this relatively closely spaced group 32 is a comparatively widely spaced group of Work units 322, and'in advance ofthe closely spaced group of work units 32 is a comparatively widely spaced work unit 323.

An elevator 34 is conveniently located at either Aside of the rails, extending longitudinally thereof, and having lifter bars 35 adapted to engage Vthe workunits beyond the rails. It will be noted that the lifter bars arediscontinuous and do not extend under the bulk ofthe close spaced group of work" units '32. 'They do, however, extend beneath the widely spaced group of work units 322 and the widelyjspaced work unit 323 and the last work unit'324 of the close spaced group.

Between Figures l and 2, the elevator isv raised, lifting .the widelyl spaced work units 322, the

widely spaced Work unit 323 and the last of the p workunits 324 of the close spaced group, to an elevated position immediately forward of dogs 3S on anupper generally horizontally extending `pusher bar3'l. It will be noted in Figures 1 and 2 that an additional work unit 325 is posi- .'tioned in raised position rearward of the elevator land supported on a return conveyor 38.

`Between the .positions of Figures 2 and 3, the

elvator'remains in raised position, and the upper pusher bars 3l are moved forward, resulting Yin advancing the work units which are elevated.

lThusA as seen in Figure 3, the widely spaced work units 322 at .the .beginning are each advanced by ,one wide space and the last of the close spaced l units 32 at the` endof the-path is likewise vadvancedby awide space. Thework unit 323,

which was formerly the last widespaced work unit, washowever, not immediately contacted bylaforrwlard projection 43 on the top pusher lhars, so that it was advanced a relatively shorter distance, being pushedpf the elevator on to an opposite portion of the conveyor 3S. At the same time the initial workvunit325 supported Von the conveyor 38 has been contacted by a forward pusher 3i on the upper push-er bar relatively late in the forward stroke, and advanced a shorter distance than that of other work units 322, to push it off'the conveyor33 on to the elevator 34.

At the same time that the upper pusher bar ,3.1 is carried forward, the lower pusher bar 33 and its VVdogs are desirably retracted, each dog ;moving back one step to a p-osition behind the next rearward work unit, and, in the case of the rearmost dog, to a corresponding blank positionbelow A*theforwardmost vwide spaced work unit 322, which still on the elevator in elevated position.

Between the positions of Figures 3 and e, the elevator moves down, carrying with it the work units supported thereon. Thus the work unit 325 and the rearmost of. the work units 322 now occupy the positions which the work units 322 occupied in Figure 11, while.. the forwardmost -of the work units 322 has joined the group 32 as shown in Figure 4. rEhe work unit 324 occupies the position of the work unit 323 in Figure l, whiie the work unit 323 in Figure 4 remains in the upper position held by the return conveyor 38.

Between the positions of Figures 4 and 5, the lower pusher bars 33 andi their wdogs move forward, carrying the group of close spaced work vunits 32'; including the last member of the group, which is the forward formerly wide spaced work unit 322 previously deposited in front of the Yrearmost dog by the elevator. Nothing happens to the ywide spaced work unit 325, to the rearward of the Vwork units 322, and to the forward work uniti-324 during this stroke. However, the conveyor 33 moves the work unit 323 from the forwardmost position to the rearwardmost posi- K tion, where it becomes the work unit 325 as seen in Figure l. The next cycle will then be carried out as indicated in Figure 1. 1n theprocedure described, it will be evident that `widely spaced work units exist at the be- V'ginning and end of the sequence of work units,

v as shown in Figure 1, and that such widely spaced f ,work units are advanced, adding one ofthe rearward widely spaced Work units to the intermediatev close spaced fvvorkV` units, and removing theV forward close spaced Work unit to make it a widely spaced work unit. Likewise the `forwardmost work unit is deposited onV a return 4conveyor and brought back' to the extreme rearward position. VIt will be evident, therefore, that the invention ,provides away of crowding inter- 'mediate work Vunits of asequence and spacing l.out initial .and iina'l work units, and where the work units are all moved through4 a single furnace space, this can tohadvantage be used to f.give more'` space. for insertion of `the first work unit and Awithdrawal of the last work unit, without requiring that the,.saine wide space be maintained throughout the furnace.

Thus it will be evident that the tendency of the Lworklunitsto swing `.andscrape the furnace wall or vto `strikeagainst ,one another can be allowed forlbyvwide spacingin .the .beginning and end of Va given Y, furnace while intermediately Vfurnace `|spacecan Tbe economized, .and heat losses mini- ;miued-by .relatively crowding the work units. It ,will also be .evident that where several furnaces .are Ain line, there may be several repetitions of the initial-.wide space, intermediate close space and finalowide'spacing illustrated in Figures 1 to 5.

hlnsuch caseFigures l to 5 ,will represent only aportionofzthe totallength vand the various .sections -inay .suitably be identical, the pusher barsiuiplybeing extended. as far as desired. Of

Y course, `l`,w-here'it Ais; desirable to employ separate pusher bars for Iindividual furnaces of the line, Figures l to 5-will represent a condition for an individual furnace of a group.

-Y- WhereFiguresb-l to 5-rrepresent the condition fora -line of furnaces-it will bek evident that a 4widespacing will frequently be employed to carry the work units over Van obstruction, such as the end wallsbetween `one furnace and the next in the sequence orU-apartitionin .afurnace Thus ,the-obstructioncould be locatedbetween two wide spaced furnacennitafor example between the wide spaced units S22-in Figurer4. It will be noted thatinprder to move the rearward one of these4 units tothe position. of the forward one,

they are always lifted and the forward motion stakes aplace in raised .-position, so `that no intermference would occur with a wall of a furnace locatedlbelow .ftherails 3.3. vAnother obstruction f can be located betweenthe last close spaced work unit and the work unit 324 of Figure 4.

In Figures 6 to 15 a structure is Aillustrated p which carries out the steps generally described furnace will, of course, vary with the `operation which is being performed, a suitable sequence being for example one of the following:

l. Carb-urizing followed by quenching.

2. Carburizing followed by an air dwell, followed by re-heat in a neutral bath, then martempering, then air cooling and finally a salt bath draw. f

3. Austempering, consisting of a pre-heat, a high heat, a quench and a draw, accomplished in separate salt baths.

4. Annealing,

5. Cyclic annealing,

6. Drawing,

7. Bra-zing. v

For example, the furnaces shown may consist of a preheat salt bath furnace3l', an austentizing salt bath furnace 3i2 and a quenching salt bath furnace 313.

The rails 30 extend continuously over the furnaces and are supported on structure 41 conveniently located at the sides, so that the space above the furnaces is kept clear for insertion, removal and translation of work units. The rails conveniently comprise opposite facing channels 48 and 53 (Figures 11 to 13), suitably joined by a strip l at the bottom, fastened as by welding. In effect a box section is produced. One of the upper flanges 52 shortened to leave a top slot 53, through which the dogs can extend. An angle 54 extends through the interior of each rail and acts as the pusher bar. The bottom flange 55 rests close against the bottom of the interior of the box section. Guiding rollers 55 are mounted along the pusher bars on studs 51 and serve to reduce the friction on sliding of the pusher bars with respect to the rails. At the appropriate intervals along the upstanding flanges 55 of the pusher bars are pivotally mounted dogs 58. rfhe dogs, in their active position, have vertically extending pusher faces 68 (Figure 11) above the rails to engage the work units, but are capable of moving to aninoperative position by swinging about their pivots BI during retraction, when the upper ends of the dogs engage and slide under the work units. The tendency to restore the dogs to their pushing position is due to the biasing on account of the: fact that the greater part of the weight of each dog is below the pivot. The lower face 62 of each dog engages `the lower iiange 55 of the pusher bar in the 12j-6 in my copending application Serial No. 41,041 filed July 28, 1948 for Pusher Mechanism.

The adjustment of the pivot 6I in the slots is facilitated by providing pivot bolts for the pivots.

The pusher bars for each pair of rails, acting through the dogs conveniently contact the Work units on the rails by engaging pusher pads 63 which are rigidly connected as by welding to header bars 64' of the work units 32. The header bars are suitably longer than the span of the rails so that they extend beyond the rails on each side for engagement by the elevator as later explained. The header bars of the work units are connected suitably intermediate their ends to hangers 65, on which the work 66 (Figure 8) is suitably held in the furnace space. `It will be understood that the details of the fixtures by which the work is held on the work holders form no part of the present invention, although suitable fixtures are shown in my copending application above referred to.

The pusher bars are desirably connected at one end by a cross connection 67 and the operation of the pusher bars is accomplished by :a suitable air cylinder 53 (Figure 15), having a piston not shown, whose piston rod 1l) pivotally connects to a link 'I0' which pivotally connects to one end of a rocker ll, on a fixed pivot 'l2 between the ends of the rocker. The opposite end of the rocker pivotally connects to a link 'I3 which pivotally connects to the cross connection 61 of the pusher bars. The piston is constantly urged toward its retracted position by a source of fluid such as compressed air admitted through a pipe 'l and on the forward stroke is actuated by fluid at higher pressure admitted from the opposite end of the cylinder, for example compressed air supplied through a pipe controlled by a valve i6, opened by the action of a solenoid l?, which is constantly urged toward the closed position of the valve by a spring not shown,`and

.. which operates to open the valve when energized.

The elevator 34 consists of a forward elevator unit 18 and a rearward elevator unit 30, spaced so as not to include the portion of the rails which carry the close spaced work units except the forwardmcst as described in Figures 1 to 5. Each elevator unit has separate portions 3l and S2 located outside of the rails so as not to interfere therewith.

On each elevator on the side toward the rails is a lifting bar 35 which extends under the overhanging end of the header bar of the work unit at each point where it is desired to lift the work unit. The elevator units are suitably suspended from cables 33 wound on drums 84, the op-posite cables at any position being cross connected by shafts 85. To assure uniformity of motion, the shafts for each elevator unit are interconnected by chains 86 on sprockets 8l. For uniformity of motion of the two elevator units, interconnection is provided by a chain 88 on sprockets 90, mounted on shafts 85 for two of the units. The shafts are carried by bearings 9i mounted on supporting structure 92 (Figure '7).

Drive of the elevator' units through the shafts, sprockets and chains is accomplished by a re versible motor 93 having opposite windings 94 and 95 (Figure 15) and interconnected to one of the shafts 35 through a belt and pulley drive 94 (Figures 6 and 7). While the motor is shown as having two windings, it will be evident that as well known it may simply employ reversible connections.

In the upper position of the elevator it is imstructure.

Vir'ediately below the upper pusher bars 31 and Vlowered out of the path of thedogs 36 during the Y retraction stroke of the upper pusher bars. The upperpusher bars 31 consist of forwardportions 95'. which are raised to clear interfering parts, slightly lower intermediateportions 96 guided. and. travelling on rollers 97, and rearward portions 98 also raised to clear interfering parts: (Figure 9). Y

The upper pusher bars are cross connected at IIIII at the: forward end and at IilI atthe rearward end. The dogs and other pusher abutments ,on the upper pusher bars are as described in Figures 1 to 5 inclusive. The rearward pusher abutment 4I as best seen inFigures 6 and 9 extends around in hook formation to clear interfering parts, and a similar construction is provided on the forward pusher abutment di).

The upper pusher bars are only put through :their forward. stroke when the elevator is raised as shown in Figure l0, bringing the work units which are raised into position behind the dogs 36 for advance of the work units. As best seen in Figure 10, the upper pusher bars 31 at their intermediate portions S6 have i sections with the body downwardly directed, so that the flanges can be guided by the rollers Si. The lifter bars '35, orrthe` elevator, support ends IJZ of the header bars of the work units as the work units are pushed forward by the upper pusher bars.

The upper pusher bars are manipulated as shown in'Figure l5y byY a iiuid cylinder 93, having a piston not shown, whose piston rod IM is pivotally connected to a link I, making pivotal connection to one endV of aV rocker ide, having a fixed pivot Il intermediate its ends. The

rocker at the opposite end pivotally connects to a link I8 which makes pivotal connection to the cross connectionY Illu of the upper pusher bars.

It is desirable to provide facilities for returning the last work unit to the position of the rst work unit, and for this purpose a return conveyor 38 is employed as best seen in Figures 6, 7, 8 and 9.

The return conveyor suitably surrounds the furnace structure at the upper level, supported on the beams which hold the upper pusher bars and the elevator mechanism. A track lle suitably guides and carries a chain III mounted at the corners on sprockets H2 (Figure 7) whose shaftsl are supported in suitable bearings.

through a reductionr gear train IM to turn the chain in any suitableA direction. Carried on the track and operativelyconnected to the chain at positions 180 apart are hook carriers H5, having their hook ends directed toward the center of the The hook ends extend into contact with the chain through an upper slot H6 in the track. rihus it will be seen that the last work unit 323 when contacted by the pusher abutment 40 and supported on the elevator, is pushed off the elevator on to hook carrier at the end, 'and ythen. carried bodily by driving the conveyor 3B to the position of the rst work unit 325 l(Figure 1). At this position on a subsequent stroke of the upper pusher bars, it is pushed off the hook car- `reloading of the work unit as indicated at 3I4.`

The

Y sprocket at one corner is driven by a motor Il3 steeper In the main embodiment. shown, the elevatorx beams extend discontinuously along the lengths of the furnaces. In some cases, however, it may be desirable to have the beams extend continuously and. simply omit the lifter bars Where it is It may be desirable, however, to lift out all work units during a period of inactivity when the furnaces4 are merely to be held attemperature, or even to :be cooled down,` emptied, cleaned V or to have thel salt bath changed. For this purpose alternate lifter bars are provided for insertion at points where lifter bars are not otherwise employed, so that all work units can be raised. At-

tachment is provided as by bolts extending through openings IIB cooperating with openings in the lifter bars `35'. Y n

In operation of the device, it will be evident that the operator will discharge and charge the work on the first work unit in lower position. The subsequent manipulation will cause this first work unit to be lifted by the elevator, pushed forward by a pusher bar dog in upper position and then lowered into the first furnace 3|. In the particular illustration shown, only one of the work units will be employed in this furnace, but it will be understood that if several of the work units Vare used they will be advanced by the lower pusher bars to the last position in this furnace. The last work unit in the iii-st furnace is then picked up by theelevator and raised to the upper position, at which it is again moved forward by the upper pusher bar a suincient distance to bridge the walls between two furnaces. On the next lowering of the elevator, this work unit becomes the rst work unit of the close'spaced sequence in the second furnace 3 I2. It is then moved forward through short steps by the lower pusher bars until it becomes the last work unit in this furnace. It will be understood, of course, that if. it is desired. to employ wide spacing in the beginning and end of this furnace, this may be done by the action of the lower pusher bars in accordance v with the principles of my copending application,

above referred to or by raising the work unit on the elevator and advancing it abnormallyY by the upper pusher bars atl the appropriate points.

The last work unit in the second furnace is then lifted bythe elevator, and in the upper position is pushed forward far enough to bridge the walls between the second and third furnaces. It is then lowered into the third furnace, where it will undergo further advance by the lower pusher bars. Y V

The last work unit in the final furnace (only one such work unit is shown) is then raised by the elevator to a position where it will be contacted by the pusher abutments on the upper pusher bars, and pushed forward off the elevator and on to the hook carrier of the return conveyor. The return conveyor is next operated through 186 to bring the last work unit to the upper position corresponding with the first work unit, at which the upper pusher bars on the next stroke push the work unit off the hook carrier and on to the elevator. When the elevator lowers, this work unit is then in position for loading and unloading to go through the cycle again. It will be understood, of course, that the unloading and reloading can be accomplished at separate stations if desired.

In some cases it is desirable to make the mechanism fully automatic, and a system of this character is indicated in Figure 15, to suggest the possibilities. A suitable source of electric current is provided through lines |20 and |2|. A timer |22, conveniently of synchronous type, includes an larmature |23, a iield |24, a contactor |25, any

en), to close the circuit through the relay switch 28 in series with the normally closed internal switch |26 and the timer eld across the line. The timer is thus started, and goes through a predeterminedtimer cycle, as well known, after which it closes its contactor |25 and' holds the same closed for a predetermined time as well' known and then momentarily opens its internal switch |26 in the well known manner. This' breaks the circuit, causing the holding relay |28 to release, while at the same time the internal switch |26 again closes to its normal position in readiness for its next cycle.

The timer contactor |25 has in series therewith a limit switch |36 normally closed by a compression spring |31 and in series with a iield winding 04 of the elevator motor to raise the elevator (suitable relays may be used if the current is too heavy for the timer contactor). Accordingly, as soon as the timer contacts |25 close, the elevator raises until an abutment I 38 on the elevator opens the limit switch |36, at which time the elevator stops, and its automatic brakes set in accordance with well known practice. At the same time that the switch |36 is opened, an abutment |40 on the elevator closes a normally open switch |4|, urged to open position by a compression spring |42. The switch |4| is in series across the line with a solenoid |43 which opens the pressure valve |44 of a fluid connection (suitably compressed air) |45 to move the piston in cylinder |03 on the forward stroke against a lower constant fluid pressure (preferably cornpressed air) applied` to the retraction end of the cylinder through a connection |46 to retract the same. Therefore `the upper pusher bars move forward.

As the up-per pusher bars |37 approach the end of their stroke, the further travel is limited by the piston engaging against the end of the cylinder and the piston remains in that position until the forward stroke pressure on it is released. An abutment lill on the upper pusher bars at the end of the stroke closes a switch |43 normally open, due to the action of a compression spring |50. The switch |48 is in series across the line with a normally closed switch urged toward closing by a compression spring |52, and which is then in closed position, and with the reverse or downward moving neld winding 35 of the elevator motor, so that as soon as the switch |48 closes, the elevator begins to move down, carrying with it the various work units in their advanced position. The elevator moves down until an abutment |53 thereon opens switch |5| and holds the same open, at which time the elevator motor stops and the automatic brakes set as well known. As the elevator moves down, the switch 4| is no longer closed by abutment l0- |40, and opens, causing solenoid |43 to release, which releases the high pressure on the cylinder 03 and exhausts the same through valve |44. The constant pressure then retracts the upper pusher bars. When the elevator comes down, a support |54 thereon, carries a pivoted abutment |55 held in neutral position by springs |56 j and |51, which engages and closes a position switch with the solenoid Tl, which applies fluid pressure for the forward stroke on thelower pusher bars. The lower pusher bars 33 then move forward until an abutment thereon encounters an operating lever ||l of the pivoted switch |58 and throws the switch |58 to open position, at which time the solenoid Valve 16 opens and permits exhaust of the high pressure fluid through the valve, and the lower pusher bars 33 retract under the constant fluid. pressure from the iiuid connection 14.

When the top pusher retracts, its pivoted spring mounted abutment |62 moves past and' closes position switch |63 in series with the return conveyor motor ||3 with which it is in series, starting the return conveyorthrough its,

opens the switch |63, stopping the motion of the conveyor.

The conveyor also at the same time closes the switch |32 and starts the action of the timer for the next cycle.

It will be evident that the invention permits great flexibility in translating mechanism to suit the particular furnace process which is being of each step at the lower level this is not necessarily the case, and the invention can be applied with any desired relation of steps at the upper and lower levels.

It will be evident that the invention is especially applicable to furnaces, but may also be applied to other devices, especially employingV liquid baths, which are generally included herein.

In view of my` invention and disclosure variations and `modiiications to meet individual `whim,

or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without cbpying.-` the process and structure shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claims. A

Having thus described my invention what l?v claim as new and desire to secure by Letters.

Patentis:

1. In furnace mechanism, a furnace having a work space, rails along the top thereof, work units` supported on the rails, pusher bars for advancing` the work units along the railsy an elevator for.

raising the work units from the rails to an elevated position and for lowering. the same,`pusher' bars in the elevated position for advancing` the work units along the elevator, and means for correlating the operation so as to rst raise the elevator carrying work units which are to be advanced at a given rate, then advance the work 'units at such rate in elevated position, then lower 58, which is in series across the lineV thel elevated Work units, and independently advance the work units at a 4different rate lbyv the 3,. In furnace mechanism, furnace means hav-V in g Work spaces, rails extending Valong the top thereof and adapted .to support work units ex.- tending into the work spaces, pusher vbars at two different levels, Vene ceeperatins with the rails and one above the rails, means for advancing the pusher bars, and elevator .mechanism outside .the rails and .includneliiier bars adapted to engage tnezworkilnits Vcnrtside the rails and extending disecntinucusly alena therails .Se as to raise Selected werk units Whileleaving other selected Work nnaifected bythe ,elevator mechanism.

4.- The nrccess ,c f translatinswork units in a pot-like V fi,irnace having a furnace Space Open at the top andrnaintainins 4spacing 7out of the units at the beginning and end of the furnacey which comprises vsiispenslrlg the work from above, raising the work units at the "beginning of the sequence, advancing the raised work units at a relatively higher rate and thereby carrying them over the furnace wall., lowering the work units until ,they are suspended in the furnace, advancins the lowered work units ai a vrelatively lower rat e rais ing the work unitsagain after they have been .advanced through the Vfurnace Space, and

Y advancing `the 'latter raised ,Work units at a relatively higher rate and thereby carrying lthem over the .furnace wall.

`5. The process of transplanting work units from one pglftype Ifurnace having a furnace Space enen at the tn to another, which comprises suspending the work from above at one level in a first furnace, pushing the work units forward step `by step as they are suspended inthe first furnace, raising the Werk units to a .higher level which clears the end wall of the first furnace, pnshing the work units forward at the higher level and at a higher rateV than that at which they advanced in the first furnace, lowerin g the work to the first level in a second furnace and there pushing the work forward at the first level.

l6,l In a furnace mechanism, a Vpot-type furnace having a furnace space open at the top and provided withY an end wall, supports for work units near the top 'ofA the furnace space, vWork units on the supports depending therefrom -into the furnace space and adapted to hold work below the supportsl in the furnace space, pusher mechanism for advancing the work units over the supports step `by step aiya lparticular rate, an elevator forV raising the work units to a higher level above the end wall and for lowering the lsame beyond the end wall and pusher -lmechanism operating at the Yhigher level rfor moving the -work vunits ywhen at Yrai/e.

aceace'/ and adapted to support work therein, elevator-` mechanism movingfrom a lower level toa higher level above the end wall and adapted to lift work units as they complete their cycle in one furnace and lower the same in the next furnace, and pusher mechanism for advancing the work units when raised by the` elevator to the higher level, whereby the work units are carried across theintervening wall space between one furnace Vand the nextand are lowered into the furnace space 0f .the HCX' furnace 8. A pot type furnace Vhaving a Afurnace space open at the iop and having an end walLrals extendine across the tcp Aof. the furnace ata low level, the ,respective rails beine at apposite sides of the furnace, Werk units 'having header bars 'extending across from rail to, rail .and Outside-the v rails, the work units extending down into the furnace .Space of the furnace, pusher bars at .thelow levels for advancing the -work units over the rails, an elevator engaging the header bars .at either side beyond the rails and adapted to raise the work units over the end Wall and lower the work 1 units beyond the end wall by engaging the pusher bars and pusher bars at an upper level for aclvancing` the work units when they are raised by the elevator.

9. In a furnace mechanism, a pot-type furnace having a furnace space open at the top,`rai1s,ex tending across the top at either side, work units riding on the rails, depending below the same into thel furnace space and ,adapted to hold work in the furnace space, pusher bars at two different levels, one corresponding with the rails and one above the level thereof, acting on the work units, an elevator located outside the rails and engaging the work units, the elevator having discontinuous lifter b ars which prevent the elevator from raising lcertain Work units and auxiliary Vlifter bars mounted in the elevator at the points of discontinuity.

LEON BIDWELL ROSSEAU.

REFERENCES CITED The following references are of record in the le of this patent:

Y UNTED STATES PATENTS

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