US2049950A - Furnace - Google Patents

Description

vAug. 4, 1936 K A.. DIXON ET AL. 2,049,950

FURNACE Filed Feb. 27, 1934 5 .Sheets-Sheet l Au@ 4s 1936- A. L. DlxoN Er AL 2,049,950

FURNACE Filed Feb. 27, 1934- 5 Sheets-Sheet 2 Aug. 4, 1936. A. L. DIXON ET AL FURNACE Filed Feb. 27, 1934 5 Sheets-Sheet 3 Aug. 4, 1936.v A. L. DlxoN E1' AL. 2,049,950

FURNACE Filed Feb. 27, 1954 5 Sheets-Sheet 4 Aug. 4, 1936. A. L.. DlxoN ET A1.

FURNACE Filed Feb. 27, 1934 5 Sheets-Sheet 5 wmv ,Patented Aug. 4, 1936 UNITED STATES PATE-NT OFFICE 2,049,950 FURNACE Application February 27, 1934, Serial No. 713,114

21 Claims.

This -invention relates to furnaces, and more particularly to electrically heated rotary hearth furnaces having a non-oxidizing atmosphere and work charging and discharging means.

An object of the invention is to improve the construction of furnaces of the character above described and provide improved means for efflciently and expeditiously charging and discharging said furnaces of work without admitting air into the furnace. 1

In accordance with one'embodiment of this invention, a furnace is provided which includes an intermittently rotatable annular hearth and an annular heating chamber having a nonoxidizing atmosphere in which the work being treated is carried by the hearth. The chamber is heated by sectional molybdenum electrical resistance elements which are clamped to each other vand to electrical terminals at points Within the chamber and exposed to the non-oxidizing atmosphere. The furnace is at all times completely sealed, thework being vcharged into and discharged therefrom by means of an air lock and associated work transfer means, vwhereby the work is transferred from an initial vatmosphere of air in the lock into the furnace non-oxidizing atmosphere in the heating chamber and discharged vice versa without admitting any substantial amount ofair to the furnace. This is accomplished by placing the work in the lock, exhausting the air therefrom, and then filling it with a non-oxidizing gas, whereupon the transfer means is operatedto move the work to be treated from the lock onto the hearth, which is stationary at this time, and simultaneously therewith transfer treated work from the 4hearth into the lock. The work transfer means is hand operated' by means of hand wheels and a lever, the operation of which is controlled by interlocking devices to insure proper sequence of operations for charging and dischargingthe furnace of work without admitting air to the non-oxidizing atmosphere in the heating chamber. Means is also provided for insuring that the rotary hearth will remain stationary during the operation of the work1 transfer means.

Other features and Aadvantages of this invention will more fully appear from the followingv detailed descriptiontaken'in connection with the accompanying drawings-lin Which `Fig. 1 is a fragmentary plan view, partly in section, of a furnace embodying the'featres of this invention; l

Fig. 2 is an enlarged fragmentary vertical section taken on the line 2 2 of Fig. 1;

Fig. 3 is an enlarged vertical section taken on the line 3 3 of Fig. `1;

Fig. 4 is an enlarged vertical section taken on the line 4 4 of Fig. 1, showing the tum-table rotated from the position shown in Fig. 1 and the inner door in closed position;

Fig. 5v is a fragmentary vertical on the line 5 5 of Fig. 3;

Fig. 6 is a fragmentary plan section, partly in section taken elevation, taken on the line 6 6 of Fig. 3; 10

Fig. 7 is a detail plan section taken on the line 1 1 ofV Fig. 3, and

Fig. 8 is a fragmentary view of an electrical heating element for the furnace heating chamber showing the method employed for securing it to 15 a terminal within the chamber ends of the element.

General Referringnow to the drawings, particularly Figs. 1 and 2, va substantially circular furnace I5 having an annular heating chamber I6 is built and to adjacent ,upon a pair of spaced inner and outer steel rings up from refractory heatinsulating bricks and the 35 top thereof, providing the vhearth floor 2l, comprises a slab of refractory 32. Annular side walls '33 of the heating chamber I6 which extend from a point slightly below the lower edge of the slab of refractory 32, at the top of the hearth, for a suitable distanceupwardly, and a top wall 34 of the chamber comprise slabs of refractory 35 and 36krespectively. Spaced from the innerrefractory slabs 35 an'd 36 arey similar outerslabs 39 and 40, outside of which is a suitable thickness of heat insulating bricks covered with steel plates 4I. Thesteel plates-I Iin cooperation with the bottom steel rings Il and I6 and an annular bottom steel enclosure interconnecting the rings comprise an airandgas tight enclosure for the furnace. In case the-bricksabutting the outer slabs 39 andl tend to sag the latter, the space provided between them and the Ainner slabs 35 and 36 'prevents the inner slabs from being deformed suflicientLv to cause interference with the work ball race 25 30 Vin a counterclockwise direction,

- the hearth stops.

, points 49 and 50,

2 being carried in the chamber i6. The supporting steel ring 28 of the annular hearth`26 has fixed thereto an annular gear 42 which meshes with a pinion 43 secured to a shaftA 44 which is intermittently driven through a speed reducing mechanism (not shown) at a desired speed to rotate the hearth 2 6 as indicated by the arrow (Fig. 1) A suitable timing mechanism (not shown) is associated with'the driving mechanism, which includes an electric motor circuit, for the shaft 44, which causes the shaft to make one revolution each hour, for instance, and then stop. The pinion 43 is of such a size relative t0 the annular gear 42 that during the one hour period of revolution of the shaft 44 the` hearth 26 will be moved one-twenty-second of a revolution and then stopped, the stopping of the hearth being indicated to the operator by the ringing of a bell included in a circuit which is closed whenf After the operator discharges and charges thefurnace vin a manner `to be described hereinafter, he closesthe motor circuit for the hearth driving mechanism by pressing a starting button and the rotation of the hearth continues. The timing mechanism and the motor and bell circuits are not shown in the drawings, since they do not form a part of the present invention and are not believed necessary to a complete the hearth 26 will be rotated in twenty-two steps and if a charge of work is placed upon the hearth during one stationary period it will again be stepped to a proper position to be discharged in a subsequent stationary period.

Referring now to side is provided with an opening 41 through which the material or articles to be treated are charged onto and discharged from the rotatable hearth 26, within the chamber I6 of the'furnace. The

chamber I6 is heated by -a plurality of electrical c resistance elements 48 made from molybdenum metal, the elements being clamped together and supported from and extending solely along the annular side walls 33 and the top wall 34 of the chamber from the point 49 to the point 50 (Fig. 1). Terminals 5I,4 also made from molybdenum of electrical current supply. The heating elements 48 are preferably made from molybdenum, a metal which is highly resistant to heat when in an non-oxidizing atmosphere, and are directly and solely exposed to a hydrogen gas atmosphere in the chamber, thegas being supplied through a plurality of inlets indicated at 52. An outlet for the gas is indicated at 53. The gas inlets 52 atV the top of the furnace extend through the plates 4I to the outer surface of the heat insulating bricks (Fig.v 2) for the purpose of flushing the brick structure of entrapped air, the gas entered therein trickling through the brick structure to the gas outlet 53 and thence to suitable means (not shown) for disposing of it. Since the heating elements 48 extend only between the the materials to be treated charged into the furnace at the opening 41 will be gradually heated as they approach the first point 49, and from the last point 58 to the discharge opening 41 the materials are cooled. Forreason the same amount of insulation is ,not required inthe annular wallof the furnace at each side of thef'opening 41 as inthe portion where the heating elements 48 are located.

'The electrical heating elements from an electric motor.

. of heating elements.

understanding thereof. Thus Fig. 1, the furnace at its right l three joined lengths of molybdenum metal of a suitable cross-section formed into a plurality of bends which extend along the side walls and the 5 top wall of the heating chamber I6, the'ends of 'the joined lengths being connected to the molybdenum terminals 5I. The three lengths of heating elements forming each section of heating elements 48 are joined to each other and-to the terminals 5| at points within the chamber I6 by U-shaped bolts and clamp plates indicated in general at 54 (Fig. 8) constructed from molybdenum metal similar to the heating elements and terminals. Fig. 8 illustrates fragmentarily one of the lengths of heating elements 48 connected at one end to a terminal 5| by a clamp 54 and another clampis shown between two lengths It has been found that this method of joining or clamping together lengths of molybdenum heating elements or to the terminals Athereof provides an. effective and convenient method of building up the resistor. Since the molybdenum is in an non-oxidizing atmosphere it remains bright and forms a good electrical connection having practically no contact resistance when clamped together and the clamps 2 presenting a larger radiating area remain cooler than the element and prevent burning out at the joint. These clamps may also be used for repairing heating elements which have become broken.

Attached to and movable with the rotary hearth 26 are a plurality of equally spaced vertically extending baille walls 45 (Figs. 1 and 2) composed of refractory material and of a shape which substantially lls the space between the side and top walls of the furnace chamber 1 5 and the floor of the hearth but freely permitting the free movement of the hearth. The walls 45 provide in the present embodiment twenty-two compartments extending around the hearth into each of which a charge of work may be placed. These baille .walls substantiallyprevent circulation of the heated gaseous medium so that the temperature in any given zone of the furnace will depend upon the heat applied to that zone.

Air lock and work transfer mechanism JThe work to be treated in the furnace is charged and discharged through the opening 41 into the chamber I6 and onto and from the hearth 26 by a work transfer and air lock mechanism indicated in general at 55 at the right side of Figs. 1 and 2. In the operation of the furnace and the associated mechanism 55, work which has been treated is withdrawn from the furnace through the opening 41 and positioned in the air lock, and simultaneously therewith work to 6( be treated is removed from the air lock and inserted through the opening into the furnace. Referring. particularlyfto Figs. 3, 4 and 5 the mechanism 55 which is bolted onto the furnace at the opening 41 with sealing `gaskets interposed 6` between theA outer steel shell provided by the plates 41 rrf the furnace and ,the mechanism, comprises a metal housing divided into inner rand outerchambers'515 and 51, the innerchamber being larger than the outer chamber. An inner rdoor 58 closes the vchamber 156 from the chamber 51 Aand the latterichamber equipped with un outer;y ooriiiffheinner .door is pisani.;

y m y ghgqrigantal rotatable Y shaft :64, the

shaft being rotatable in either direction, by means which will be described hereinafter, to open and close the door 58. -The door 58, due to its pivotal mounting 62, alines itself with a door frame II between the chambers 56 and 51. Gaskets II are carried upon the opposed surfaces of the door Il and the frame 6l to form an `air--tight seal when the door is closed. Adjustable stop pins I1 carried by the arm I3 serve to limit the movement of the door I8 about the pivot l2 when the door is opened.

The outer door is is carried upon an arm 6| which may be swung about a vertical axis 1l (Fig. 1), the connection between the door and the arm comprising a hand screw 12 threaded through kan aperture in the arm and connected at its inner end with the door so that the door may be moved by rotating the hand screw. A pin 13 iixed to the door extends loosely through an opening in the arm l! to prevent the door from rotating upon the arm. A U-shaped hand actuated catch 16 is pivoted upon the mechanism i5 and arranged to be swung over of the -arm 69 when the latter is turned to its door closing position. When the catch 1i is thus positioned, che hond sei-ew 12 may be rotated to' move the door 58, connected to the screw, into position against a'door frame 11, the thrust of the screw outwardly being taken by the'catch. The opposed surfaces ofvthe door 59 and the frame 11 are equipped with gaskets 18 (Fig. 5) to provide' an air tight seal for the chamber.

Interlock between inner and outer doors vented from being opened when the inner door 58 is opened. 'I'his is eiected by a spring drawn latch 19 pivoted at I0 to 'the inner side wall of the outer chamber 51, the latch being drawn into locking engagement with a keeper 83, fixed to the inner surface of the outer door 59, when the inner door 58 is swung open. When the door 58 is closed, the door is moved into engagement with an adjustable pin M carried bythe latch 19, which swings the latter counterclockwise to move it from locking engagement with the keeper Il on the outer door 59 to the position shown`in Fig. 4. Also by means, which will be described hereinafter, the inner door 58 is prevented from being opened during ation of the mechanism 55.

l Turn-'table of work transfer mechanism Disposed in the inner and larger chamber 58 is a rectangular shaped turn-table 85 (Figs. 3, 4 and 5) comprising a frame 86 having slides l1 at opposite ends of the frame guided therein and extensible therefrom and retractable thereto, the upper surfaces of the slides being in the' plane of the upper surface of the frame. The work to be heat treated in the furnace is loaded into trays Il composed of ceramic material, the trays being formed with U-shaped openings SII at their bottoms for the reception of 'the slides 81, which are slightly tapered along their upper and lower edges at their outer ends so that they will freely enter the openings in the trays. In placing a, tray 89 in the outer chamber 51, it is predeterminediy positioned onailoor 9| chamber 51l so that'when one of the slides l1 is -hearth 26 at a standstill.

. .is .iournaled at its lower end the free end certain steps in the oper.

of the outer 3 mechanism Il when the turn-table II has been rotated to the proper position, the slides l1 may be simultaneously extended so that one slide will be enteredin theopening I ofthe'trayil carryingtreatedworkormaterialandcarriedonthe 5 annular hearth 2Q and the other slide will be entered in the opening Il ofthe-tray l carrying work or material to be treated and whichhas been positioned in the small outer chamber i1. the inner and outer doors n and le et inietimo iobeing opened and closed, respectively, and the 'Ihe turn-table li in addition to its rotary movement is alsoy adapted to be raised and lowered for the purpose of picking up the trays Il and depositing them in re- .l5 verse positions in a followingobration of the turn-table, in a manner which will be described hereinafter.

Operating mechanism for turngtable A vertical rotatable shaft I! (Figs. 3, 5 and 6) in spaced stationary bearing brackets Il. the upper-end thereof extending into the inner chamber Si. rotate with the shaft az, es indicated et sa, but 2 permitting the shaft to be moved longitudinally upwardly and downwardly is a helical gear SI which isarranged between the stationary brackets I3. Fixed to the upper end of the shaft 02 is a pinion 91 which meshes at diametrically op'a0 posite points-,with aipair of- 4gear racha Il, slide ably mounted in the turn-table frame It and connectedjothe slides l1. Upon the shaft l2 being rotated the slides l1 will be moved to an extended position or moved toa retracted posiu tion on the frame I6, dependingupon the direction of rotation of the shaft. Surrounding the shaft 92 atits upper end is a rotatable sleeve II vto which the turn-table is secured for rotation therewith. 'Ihe sleeve .l is gitudlnally slidable in a" bearing il equipped with a stuiling gland III whichA serves to eii'ect an air-tight seal for the chamber 56 at this point. Surrounding and fixed to the sleeve l! is a clutch element Ill to the upper end of which is secured a dise lli, the lower end of the element having clutch teeth. The disc III "is provided with a pair of 4diametrically opposite peripheral notches |06 and cam plates lill iFlgs.- 3 and 6) secured to its undersurface, which will bei referred to hereinafter, the cam plates being predeterminedly spaced anguiariy from the notches. Rotatably carried at its upper end upon the clutch element I Il, as indicated at ill (Fig. 5), and at its lower end of the point^||2 upon the shaft l2. is a member III with a bifurcated portion III, the

clutch element |04 and the shaft 9 2 being free to rotate relative to the member H3. A clutch element III provided with clutch teeth at each vend is slidably mounted on the shaft 92 but keyed 0 'ment will follow.

A lever III formed with bifurcated ends .is plv-- oted at I2., the furcations at its right end (Figs. 3, 5 and 6) being pivoted to the furcations of the portion Ill of the member Ill. and the furcations 15 at its left end. being pivoted toa nut (Figs. 3 and 6) threadedly engaging a vertical rotatable screw |22. A bevel gear is fixed to the screw |22 and opposite ends of theA screw are rotatably journaled in stationary brackets |26 in such a manner that the screw will not move longitudinally. Meshing with the bevel gear |25 is a similar gear |2`| which is connected to 'a rotary hand wheel |28 journaled upon and arranged outside of the housing of the` work transfer unit v55. v Upon the hand wheel |28 ybeing rotated the screw |22 will also be rotated and through the meshing gears |25 and |2| the nut |2| will be caused to travel upwardly or downwardly upon the screw, depending upon the direction of rotattion of the hand wheel, thus. causing the lever ||9 to be rocked about its pivot and thereby elevating or lowering the member ||i and with it the sleeve 99, shaft 62, clutch elements` |06, H6, and and the turn-table 85. Suspended from the lever H6 at a point adjacent the nut |2| are weights |30 which serve to counterbalance the weight of the turn-table 65 and connected elements and the work being transferred.

The clutch element M5 may be shifted upwardly upon the shaft 02 to which it is rotatably fixed by a bifurcated lever |3| pivoted to the member |3 (Figs. 3 and 6) the furcations of the lever carrying pins |32 which engage in a peripheral channel formed in the clutch element. The lever |3| which is positioned below the lever ||6 and extends at an angle to the latter lever has its furcations disposed within the furcations of the lever ||9 and is pivoted between the walls of a vertical slot |33 (Fig, 6) of the member M3 by a pin |36. Operatively connected to the lever |3| by a vertical link |65 is a hand lever |36 Which extends outside of the housing of the unit 55, the link being pivotally connected to the levers at |36 and |40 and the lever |36 isi pivoted at |4| (Fig. 6) to the housing. When the hand lever |30 is raised or rocked clockwise about its pivot, the clutch element H5 will be shifted upwardly to disengage its lower teeth from the clutch element and engage its upper teeth with the Vclutch element |66. This, it will be apparent, may be effected when the member i3 is either in its lower or upper position.

Slidably mounted in a boss |62 formed on the member ||3 (Figs. 3 and 6) is a longitudinally slidable spring pressed plunger |63 which at its upper end, as shown in the position of the parts in Figs.`3 and 6, is entered in oneof the notches |06 of the disc |05. When the plunger |63 is entered in one of the notches |06 it will be apparent that the turn-table cannot be rotated from the'shaft 92. The plunger |63 is normally held in its upper position by a compression spring |44 surrounding the plunger with its opposite ends abutting the upper surface of the boss |42 and a collar |45 xed to the plunger. A pin y|66 xed to the plunger |43 is entered at opposite ends in suitable slots provided in opposite portions of the lever |3|, the plunger extending between the lever portions. When the hand lever |30 is raised the clutch element H5 is shifted upwardly through the lever' |3|, and the shaft 92 and the sleeve 99 are rotatably connected together, thus completing the rotary drive to the turn-table 85. At this instant the movement of the lever |3| which is counterclockwise and connected to the plunger |43 by the pin |46 moves the plunger downwardly, compressing the spring I and withdrawing its upper end from the cooperating notch |06 of the disc |05, thus unlock- `wise by means of the hand wheel |26, the

acteert ing the turn-table 05 so that it may be rotated. Meshing with the pinion ||6 on the clutch element is a gear |66 rotatably mounted as indicated at |60 on the member M3. Formed in the upper surface of the gear |06 is an aperture |50 for receiving the lower end of the plunger |43 when it is moved downwardly as above described, the gear at this instant being positioned so that the aperture is alined with the plunger.

, The gear |410 is formed, with a. downwardly extending ange |5| provided with a vertical slot |53 spaced a predetermined angular distance from the aperture |56'.

Fixed to the lever il@ is a depending arm |54 having a vertical finger |55 at its lower end which is arranged to enter the slot |53 of the gear flange |5| and pass within the inner periphery thereof when the lever is rocked counterclock-t-l slo at this time being alined with the finger. The gear |40 in subsequent operations during which the slides 6i are being extended or retracted is rotated and the slot |63 is thereby moved out of alinement with the finger |55 attached to the lever H6, thereby interlocking the nger behind the inner periphery of the gear flange |5|', which thereby prevents the lowering of the turn-table 85, since the lever cannot be rocked clockwise about its pivot. When the iinger |55 is positioned outside the periphery of the gear ange 10 |5|, as shown in Figs. 3 and 7, and the gear slot |53 has been moved out of alinement with the finger, the lever M6 cannot be rocked counterclockwise about its pivot, and thus the elevation.

of the turn-table 65 is prevented during opera- 'i tions in which the slides 6l arebeing extended or retracted. y

Simultaneously with the above described disalinement or the gear slot |53 and the finger |55 the gear aperture |56 will be moved out of alinement with the plunger |63, which serves to prevent the rotation of the turn-table 65 during operations in which the slides 6l are being extended or retracted. When the slides 6l are partially extended or retracted the plunger |03 will be in its upper position and the lower end thereof will lie close to the upper surface of the gear |66, with the result that if an attempt is made at this time to raise the lever |36 to engage the clutches H5 and |06, theplunger will engage the upper surface of the gear which acts as a stop.

The shaft 92 is rotated from. va hand wheel |56 arranged alongside of the hand wheel |28 through a shaft |57 carrying a helical pinion |58 which meshes with the helical gear keyed to the shaft 92, the shaft |51 being suitably journaled at opposite ends in bearing brackets.

For opening and closing the inner door 56 there` .is provided a hand wheel |59 iixed to a horizontal shaft |60 (Figs. 5 and 6), the hand wheel being arranged alongside of the hand wheel |56. Rotary motion from the shaft |60 is transmitted to a vertical shaft |6| through bevel gears y end extending into the path of the cam plates 75 Vwith an aperture at its left Zend is operatively with the upper end of the plunger |1| which extends through the aperture, the plunger engaging the upper surface of the lever. At its right end the lever |14 is formed with a latch |19 for engagingA a notch in the shaft |68. A tension lowered with the as shown in Figs. 3, 5 and 6. When-the plunger |1| is pressed downwardly by one or the other of the cam plates |88 moving into engagement therewith, the lever is rocked counterclockwise and the latch |19 is withdrawn, thus permitting the inner door 58 to be closed by rotating the hand wheel |59. l

When the inner-door 58 is closed as shown in Fig. 4 the hand wheel |55 is locked from rotation, so that the turn-table cannot be rotated or elevated. This is eifected by means of a latch |82 (Figs. 3 and 6) slidably mounted in a bracket supporting the helical pinion |58. A compression spring |88 Surrounding'the latch |82 and abutting at opposite ends against a collar fixed to the latch and a stationary guide, through which the latch extends, normally acts to maintain the latch in locking engagement between adjacent teeth of the pinion |58. Carried by the gear sector |68, included in the mechanism for opening and closing the inner door 58, is a cam member |88 (Fig. 3) which during the opening of the door moves into engagement with a roller |81 mounted on-a vertically slidable bar |88, the latch |82 and the bar being connected together r by a. link |89 pivotally connected at opposite ends thereto. As the inner door 58 reaches its open indicated in dotted outline in Fig. 4, the latch |82 is withdrawn from locking engagement with the pinion |58 to the position shown in Fig. 3.

Stepbystepro the hearth will are in their elevated position during certain steps A `in the operation of 4tioned on the the work transfer unit 55, the cam plates |88 carried by the disc will move idly by the plunger |1| and the latter will consequently remain in its upper open circuit position.

same for heating chamber 5 A baille indicatedin general at |92 (Figs. 1, 2, 3 and 5) Veilectively prevents the-'egress of hot hydrogen gases from the heating chamber I5 into the inner chamber 58 through the furnace opening 41, at all times, except. during the charging and discharging of work into and from the furnace. The baille |92 comprises a base plate |93 surrounding the turn-table 85 below the frame 86 thereof and supported on a floor |98 of the l5 inner chamber 55. Fixed to the base plate |98 is a pair of diametrically opposite sockets |85 for freely receiving the lower ends of pins |88, secured to opposite sides of the turn-table frame 86, when the latter is in its lowered position as 20 shown in Figs. 1, 3 and 4. As thus connected to g the turn-table frame 85 the bame |92 may be rotated with the turn-table during certain steps in the charging and discharging of work into and from the furnace and upon the turn-table being 25 from the furnace opening 41, the plate |98 which is arc-shaped carries a vertical member |91, similarly shaped, having its .opposite vertical edges at their upper ends connected together with a still'ening plate |98 (Fig. 1). The total 35 height of the vertical member |91 and the plates |93 and |98 is such that they closely llt within the height of the opening in the housing of the mechanism 55 where it joins the opening 8 1 but may be freely moved therein. Fixed to the 0pposite vertical walls of the housing of the mechanism 55 at the opening 81 (Fig. 1) are filler plates |99 which are turned inwardly at their inner ends and directed toward the opening 81.

Operating cycle In the operation of the herein described furnace and air lock and work transfer mechanism 55, let it be assumed that the turn-table 85 is in a quiescent position, as shown in Fig. 4, in which position the baille |92 intermittently rotatable therewith, has closed the opening 81 into the heating chamber I6 to prevent the egress of hot hydrogen gas therefrom into the inner chamber 56, the inner door 58 being in a closed position, a tray 89 of material to be charged onto the hearth 26 has been predeterminedly posifloor 9| of the outer'chamber 51, the outer door 59 of which has been manually closed, and the rotatable hearth 28 is at rest o0 during one of its stationary periods with a tray 89 of heat treated material centered with the furnace opening 41 and alinedwith the turntable 85 ready for discharge. I t is also assumed at this time that the outer chamber 51 has been 65 exhausted of air and then filled with hydrogen gas, in' a manner to be described hereinafter. Starting with the furnace and the mechanism 55 conditioned as just described a complete cycle of operation of the mechanism to insert the tray 70 89 of material to be treated into the furnace from the floor 9| of the outer chamber 51 and to remove a tray 89 of treated material from the furnace, which latter tray is stationary and alined with the opening l1 and the turn-table 75 85, and deposit it upon the oor of the outer chamber is as follows:

Inthe quiescent position of the turn-table 05 (Fig. 4) the upper end of the spring pressed interlocking plunger |03 has been withdrawn from one of the notches B00 of the disc |05 and is abutting the under surface of the disc and the lower end thereof is entered in the aperture |50 of the gear i430, and the nger I55 carried by the lever H0 is alined with the slot l53vof the ange I5!! of the gear 08 and is positioned outside the periphery of the flange. Also with the plunger |43 in its lower position the clutch element H5 is maintained in its upper position in engagement with the clutch element |104 by means of the connection between the plunger and the lever I3l. It is also to beunderstood that the latch |19 has been withdrawn from the notched collar on the shaft |00 so that the hand wheel |59) is free to be rotated to open the inner door 58. The described positions of the plunger |43 and the' latch H5 were effected automatical ly at the completion of the last work transfer operationand will be further described upon completion-of the cycle ci operation being described. 'Ihe operator now opens the inner door 58 to the dotted position thereof, shown in Fig. 4, by rotating the hand wheel i5@ clockwise, which withdraws the latch H02 from locking engagement with the teeth of the pinion |58, thus free= ing the hand wheel-|56 and permitting the turntable to be rotated. The hand wheel $50 is now rotated counterclockwise, which causes a clockwise rotation of the turnetable 85, the rotation continuing Auntil one of the notches |00 of the disc i105 spaced at this time 90 fromv the vplunger i513 is moved into alinement with the plunger, which immediately springs into the notch and thus prevents further rotation of the turn-table, the lower end of the plunger being withdrawn from interlocking engagement with the gear M0, which is now free to be rotated.

The operating elements of the work transfer4 mechanism 55 have now been operated to the positions thereof as shown in Figs. l, 3, 5 and' 6. Simultaneously with this movement of the plunger |03, the clutch element l l5 returns to its lower position in engagement with the clutch element Ill, through the action of the spring |40, pulling thev plunger upwardly, which by means of its connection with the lever ISI, which is rocked clockwise, moves the clutch element downwardly. At the beginning of the 90 rotation of the turntable 85 one of the cam plates E08 carried by the disc |05 and whichhas been operatively en,k

gaged with the spring pressed plunger lli moves away and the plunger immediately moves upwardly and actuates the switch |00, thereby insuring that the circuit to the motor will remain open during the operation of the transfer mechanism 55" and the rotary hearth 26 remain stationary.

' The slides 8l of the turn-table 05 are now simultaneously extended into the heating chamber I5 and outer chamber 5l and into the openings 90 of the trays 00, which are alined in the two chambers, by rotating the hand wheel |50 counterclockwise and thereby through the mechanism previously described the racks A08 attached to the slides are moved outwardly. During this outward movement of the slides 8l the shaft 92 was rotated clockwise and through the clutch element ||5 engaged with the clutch element II'I carryingthe pinion lla, the gear M0 is rotated countercloclrwise. Thus the gear slot |53 is assenso lalso be alined with the plunger M3. The turntable 05 is now elevated'to pick up the trays 09 in preparation for a`l80 rotation of the turn'-` table to transfer the tray which is in the outer chamber 5l to the heating chamber l5 and the tray in the latter chamber to the outer chamber. To elevate the turn-table 85 .the hand wheel t28 is rotated clockwise, w 'ch rocks the lever I9 counterclockwise and thereby moving upwardly, as a unit, all of the elements surrounding the shaft 02 which are positioned above the lower end of the member I I3. During this movement of the 20 lever I|9 the interlocking nger |55 is rocked into the gear slot 653 and within the inner periphery of the ilange of the gear, but no locking of the finger to the gear takes place until the gear is again rotated during a retraction of the 25 slides 8l from their extended positions. The turn-table 85 is held in its upper position, with the trays 09v supported thereon, by the cooperating nut |2i and the screw |22 associated with the hand wheel H20. t

The slides 0l carrying the trays 89 are now retracted to position them within the inner chamber 50 so that the turn-table 85 may be rotated therein to reverse the position of the trays. To retract the slides 8l the hand wheel |56 is ro- 35 tated. clockwise, the racks 98 with the attached slides being moved inwardly. This rotation of the hand wheel |55 also through the rotation of the clutch element I l5 rotates the clutch element I Il carrying the pinion l I8, which in turn rotates the gear |40 clockwise to again aline the gear aperture |50 with the plunger |43 and also the gear slot |53 with the interlocking finger |55. The disengagement ofthe clutch element H5 from the clutch element lill during the retraction of the slides 0l' by a raising of the hand lever |38 is prevented by the lower .end of the plunger M3, which during this time is out of alinement with the gear aperture |50, and is engaging the upper surface of the gear M0. Thus a premature rotation of the turn table 85 with the slides 8l in a partially retracted position isavoided. This same result is obtained by the disalinement of the plunger |43 andthe gear aperture |50 during theextension of the slides 0l.

With'the slidesr 3l ina fully retracted position the turn-table 85 is rotated clockwise 180. This is'eilected by rst raising the hand lever |38 which moves the clutch element I I5 upwardly and operatively connects the shaft 92 to the turn- 60 table. Simultaneously ,with this movement .of the clutch element M5, the lever |3| at its left end is rocked downwardly and through its connection to the plunger |43 by means of the pin |46 and the slots of the plunger and the lever, 65 respectively, the plunger is moved downwardly. The upper end of the plunger |43 is thus withdrawn from the notch |06 of the disc |05, thereby unlocking the turn-table 85 for rotation, the plunger at its lower end entering the aperture I 50 of the gear |48 and locking the gear from rotation, the aperture being previously alined with the plunger at the termination of the retraction of the slides 81.

this rotation of the 5 The purpose of locking the gear from rotation and thereby the clutch element ||1, which occurs whenever the clutch element ||5 isdisengaged from the clutch element ||1 is to maintain the position of the latter clutch element so that when the clutch element ||5 is lowered .to engage the clutch element |1 ments will accurately register in driving engagement. The hand wheel |56 is now rotated counterclockwise, while momentarily holding the hand lever |38, still in a raised position, until the notch |06 of the disc 05, from which the plunger 43 was withdrawn, is moved out of alinement therewith and engages the under surface of the disc. 'I'he rotation of the hand wheel |56 is continued until the other notch |06 which vis spaced 180 from the notch from which the plunger |43 was last withdrawn is moved into alinement with the plunger, which immediately springs into the notch and thus prevents further rotation of the turntable 85, the plunger at its lower end being withdrawn from interlocking engagement with the gear aperture |50. In a manner similar to that described in connection with the 90 rotation of the turn-table the clutch element ||5 returns to its lower position as shown in Figs. 3'and'5.

The position of thehtrays 89 have now been reversed by a 180 clockwise rotation of the turntable 85 within the inner chamber 56 and are ready to be inserted in the heating chamber I6 and the outer chamber 51 by the slides 81 being extended on the locked and still elevated turntable. The hand wheel |56 is now rotated in a counterclockwise direction which, in a manner similar to that described in connection with the previous extension of the slides 8 1 in preparation for picking up the trays 89 from the rotary hearth 25 and the oor 9| of the outercchamber 51 causes the slides to be'extended into the chambers |6 and 51 and rotates the gear |48 counterclockwise, the gear slot |53 at the termination of theextension of the slides being again alined with the interlocking nger |55 carried by the lever ||9. The turn-table 85 is now free to be lowered by means of the hand wheel |28. The linger |55 during this rotation of the gear 48 is still within the inner periphery of the ange |5| of the gear so that a lowering of the turn-table'85 during the extension of the slides 81 is'prevented. Also during this rotation of the gear |48 the aperture |50 thereof moves out of alinement with the plunger |43 so that the plunger lies over the upper surface of the gear to prevent, as described hereinbefre, a premature rotation of the turn-table 85`while the slides are in a partially extended position during the retraction thereof.

With .the slides 81 extended the tray 89 of material to be heat treated is positioned in the chamber I6 over the still stationary hearth 28 and the tray of treated material is in the outer chamber 51. The turn-table 85 is now lowered to deposit the reversed trays 89 on the hearth 26 and the floor 9| of the outer chamber 51 byrotating the hand wheel |28 counterclockwise which is opposite to its direction of rotation in elevating the turn-table, as previously described. During this operation ally of the elements previously mentioned in connection with the elevation of the turn-table are lowered, as a unit, to the position shown in Figs. 3 and 5 Also at this time the interlockingV finger |55 Yis withdrawn from the allned slot |53 of the gear |48 and to the position shown in Figs. 3 and 7. Following this the slides 81 are retracted into the inner chamber 58 by a clockwise rotation of the the teeth of the clutch ele" turn-table hand wheel |56, similar `to the operation of retracting the slides when they were carryingl the trays from^the hearth and outer chambers |6- and 51, respectively, into the inner chamber 56. Simultaneously with the retraction of the slides 81 the gear |48 is rotated clockwise to move the gear slot |53 out of alinement with'the interlocking nger- |55, which at this time is inV 'the position shown in Figs. 3 and 7 adjacent the outer peripheral surfaces of the flange of lthe gear |48, thereby preventing theelevation of the 85 during the retraction of the slides beapparent that with the nger|55 81. It Will 'adjacent the outer peripheral surface vof the flange o f the gear |48 with the slot out of alinement therewith, the lever |9 which carries the finger cannot be rockedto elevate the turn-table.l Thislast mentioned rotation of the gear |48 also moves the laperture |50 thereofagain' into alinement with the plunger 20 43 at the termination of the retraction of the slides 81. 'f i To complete the cycle of operations the turntable 85 is now rotated counterclockwise 90 to |53 thereof a quiescent position as shown in Fig. '4. The 25 furnace opening 41.

VDuring this vrotation of the turn-table ss the rotation of the turn-table85 up to this point in the'cycle of operations has been in a clockwise direction. This final rotation in a counter- 'clockwise direction of the turn-table 85 is for the purpose of moving the bathe |92 to close the 30 The operation ofthe baille |92 will bedescribed hereinafter. This 90 rotation ofthe turn-table 85 is accomplished by rst raising the hand lever |38 to actuate the operatively connected parts, followed by a clockwise 35 rotation of the'hand wheel |56, in a manner similar to that described in connection with the raising of the lever and the rotation of the hand wheel'for the 180 rotation of the turn-table 85, with the exception that the rotation of the turntable by meansof the hand wheel |56 is continued only uniil the turn-table is positioned as shown in Fig. 4, wherein itis positioned at right anglesto its position as shown in Figs. 1, 3 and 5.

plunger |43 which has been withdrawn from one of the notches |06 of the disc |05 is abutting the under surface of the disc and the' lower end thereof is entered in the gear aperture |50, the turntable thus being free tov be rotated in the next Work transfer operation. To facilitate the positioning 'of the turn-table 85, as just described,` the side wall ofthe inner chamber 56 where the operator stands when manipulating the various hand wheels and the levr is provided with a glass 55 window 200 (Figs. l and 3),' which permits the.

operator to view 'the rotation of the 'turn-table. Upon the completion of this 90 rotation of the turn-table 85 one of the cam plates |08 carried by the disc 05 moves into engagement with the plunger |1|, depressing it and thereby preparing the motor circuit at this point for closing by means of the ,starting button, which may then be actuated to start the annular hearth 26 rotating. Simultaneously with this movement of the plunger |1| the latch |19 of the lever |14 is withdrawn from the notch of the collar |80, which permits the operator to close the inner door 58 by rotatingthe hand wheel |59.A The closing of the inner door 50 permits the latch |82 to move into locking engagement with the teeth of the pinion |58, thus locking the hand wheel |56 from rotation and thereby preventing the turn-table 85 from being rotated or elevated when the inner door is closed. Since the switch 75 table 85 is in its sockets |95 of the baille eflicient electrically lthe turn-table toits quiescent |90 has been actuated to close the motor circuit for rotating the hearth 26 when the turnlowered quiescent position it lwill be apparent that by locking the hand wheel |56 the accidental elevation of the turn-table at this time is positively prevented. With the inner door 58 closed the latch 19 has been drawn from locking engagement with the keeper 83 on the outer door 59, which may then be opened' and another tray 89 of material to be heat treated is inserted in the outer chamber 51 in preparation for the next be understood that before opening the outer door 59 to remove the treated material the hydrogen gas isexhausted from the chamber 51 through an outlet 28| (Figs.l and 4) which may be connected -to a vacuum pump (not shown). The outer door 59 is then manually closed and secured by the hand screw 12 and the catch 16 and thereafter the air is exhausted from the outer chamber 51 through the outlet 20|, in a manner similar to that described in connection with the exhausting of the hydrogen gas therefrom and thereafter hydrogen gas is admitted through an inlet 292 connected to a source of supply, which also-supplies the heating chamber I6, the outlet and the inlet being controlled by handvvalves (not shown).

operation of baule In the operation of the air lock and work trans fer mechanism just described the baffle |92 is operated as follows: In the quiescent position of the turn-table 85 (Fig. 4) wherein it is in its lowered position, the pins |96 are engaged in the |92, the latter .being in position to close the furnace opening 41. In the initial clockwise 90 rotation of the turn-table 85 the bafiie |92 is rotated therewith to the position shown'in Figs. 1, 3l and 5. Following this, the slides 81 are extended andv then the turn-table 85 is elevated, which elevation withdraws the pins |96 from'the sockets |95 of the baille. The slides 81 are thereafter retracted. `During the 180 rotation of the turn-table 85, which follows, the baille |92 remains stationary. Thereafter the slides 81 are extended, which is followed. by` the lowering of the turn-table 85 which enters the pins |96 carried thereby into the sockets |95 of the baiile |92, thus again connecting the badle to the turn-table so that in the flnal 90 rotation of position, which is in a counterclockwise direction, the baffle will be moved to again close the furnace opening 41.

It' is believed that the advantages of the present invention will be clearly apparent from the above detailed description of construction and operation. The described construction provides a very heated rotary hearth hydrogen gas furnace.

Although the invention as herein illustrated and described is particularly applicable to furnaces of the character above described, it should be understood that the novel features of the invention are capable of other applications within the scope of the appended claims.

What is claimed is:

1. In a charging mechanism adapted for use with a furnace, a rotatable element having a plurality of members extensible therefrom in opposite directions for supporting articles, and means for actuating said extensible members,

2. In a charging mechanism adapted for use with a furnace, a rotatable element having a plurality of members arranged in a common accanto work transferoperation. It is tov lock into the furnace, an

plane and extensible therefrom at opposite points for supportingarticles, and means for actuating said extensible members.

3. In a charging mechanism adapted for use with a furnace, alrotatable and vertically reciprocable element having a plurality of members extensible therefrom for supporting articles, means for extending and retracting said members to position them under and withdrawing them from the articles, means for elevating said element and the extended members when the articles are supported thereon, and means for rotating said element when said extensible members carrying the articles have been drawn inwardly to reverse the position of the articles.

4. In-a charging mechanism adapted for use with a material treating furnace having a charging and discharging opening, `a rotatable baille at thefurnace opening to close the same except when the furnace is being charged and discharged, a charging mechanism operable for charging untreated material into the furnace and discharging treated material from the furnace during an operating cycle, operative connections between said mechanism and said Abaille cooperating to cause the baille to be moved from the furnace opening during an initial portion of the operating cycle of said mechanism, said operative connections permitting said bafe to be automatically disconnected. from the mechanism and remain stationary during an intermediate portion of the operating cycle and during a ilnal portion thereof to be automatically connected to said mechanism and moved to close the furnace opening, and means for operating said charging mechanism to complete a cycle of operations.

5. In a charging mechanism adapted for use with a hydrogen material treating furnace havlock at the furnace opening comprising inner and outer chambers, means operable in said inner chamber for charging material through said air inner door between said chambers, an outer door for said outer chamber, actuating means for said inner door, and interlocking means operatively associated with said door responsive to an opening of said inner door for locking said outer after closure until said inner door is again closed. 6. In a charging mechanism adapted for use with a hydrogen material-,treating furnace hav' ing a charging and discharging opening, an air lock at the furnace opening.. comprising innerand outer chambers, an inner door between said chambers, an outer door for said outer chamber,

actuating means for said inner door, a keeper fixed to an innersurface of said outer door, and interlocking means disposed between said doors comprising a pivotal lever having a latch at one end operatively engageable with said keeper in one position of said lever, the opposite'end of said lever positioned in the path of and operatively engaged by said inner door, d means constantly urging said lever to move to operatively engage said keeper, said interlocking means responsive to an opening of said inner door for locking said outer door from being opened after closure until saidinner door is again closed.

7. In a charging mechanism adapted for use with a furnace, a reciprocable element having a plurality of members extensible therefrom for supporting articles, actuating means for extending and retracting said members, means for actuating said element with the members extended or retracted, and interlocking means operatively door from being openedv associated with said means for extending and retracting said members and said means for moving said element responsive to an actuation of said former means for locking said latter means from actuation so that said element cannot be moved While said members are being extended' means from actuation so that said element cannot to be elevated or lowered While said members are being extended or retracted,

9. In a charging mechanism adapted for use with a furnace, a rotatable element having a plurality of members extensible therefrom for supporting articles, actuating means for extending and retracting said members, actuating means for rotating said element with the members extended or retracted, and interlocking means operativeiy Yassociated with said means for eX- tending and retracting said members and said means for rotating said element responsive to an actuation of said former means for locking said latter means from actuation so that said element cannot be rotated while said members are being extended or retracted.

10. In a charging mechanism adapted for use with a furnace, a rotatable element having a plurality of members extensible therefrom for supporting articles, actuating mechanism for extending and retracting said members, actuating means for rotating said\ element including a clutch mechanism, means y for actuating said clutch mechanism, means operatively connected to said actuating mechanism for said members and movable during an extension or retraction of said members to predeterminedly position a stop surface thereof, and a stop element carried by said clutch actuating means and movable during an actuation thereof into abutting relation with said stop surface to render said clutch actuating means inoperative to cause a rotation of said element during an extension or retraction of said members.

11. In a charging mechanismadapted for use with a furnace, an air lock at the furnace opening comprising inner and outer chambers, an inner door between said chambers, an outer door forV said outer chamber, means operable in said inner chamber for charging material through said air lock into the furnace, individual means for actuating said inner door and said charging means, and interlocking means operatively associated with said individual actuating means and controlled by said means for actuating said charging means for rendering said means for actuating said inner door inoperative to close said door during the-actuation of said charging means.

12. In a chargingmechanism adapted for use with a furnace, an air lock at the furnace opening comprising inner and outer chambers, an inner door between said chambers, an outer door for said outer chamber, means operable in said inner chamber for charging material through said air lock into the furnace, individual means Vfor actuating said inner door and said charging means, and interlockingmeans operatively associated with said individual actuating means and controlled by said means for actuating said inner door for rendering said means for actuat- 5 ing said charging means inoperative while said inner door is closed.

13. In a charging mechanism adapted for use with a furnace having a movable hearth, a rotatable element having oppositely movable means thereon for supporting articles to be positioned upon and removed from the hearth, and means for actuating said movable means.`

14. In a charging mechanism adapted for use with a furnace having a movable hearth, a rotatable element having a plurality of members extensible therefrom in opposite directions for supporting articles to be positioned upon and removed from the hearth, and means for actuating said extensible members.

15. In a charging mechanism adapted for use with a furnace having a rotary annular hearth, a rotatable ,element having a plurality of members arranged in a common plane and extensible therefrom at opposite points for supporting articles tobe positioned upon and removed from the hearth, and means for actuating said'extensible members.

16. In a charging mechanism adapted for use with a furnace having a movable hearth and a 30 furnace charging and discharging opening, an air lock at the furnace opening comprising inner and outer chambers, an inner door between said chambers,- an outer door for said outer chamber, a rotatable element within the inner v`chamber having movable means thereon for supporting articles to be positioned upon and removed from the hearth, and means for actuating said movable means.

17. In a charging mechanism adapted for use 40 with a furnace, a rotatable element having a' plurality of members extensible therefrom in opposite directions for operative engagement with articles to be entered into and discharged from the furnace, and means for simultaneously actuating said members to operatively engage th articles, retract the members with the articles, rotate said element to reverse the articles, actuate said members to position the reversed articles', and thereafter retract the members from the reversed articles.

18. In a charging mechanism ladapted for use with a. furnace, a rotatable shaft, a rotatable andvertically reciprocable -sleeve surrounding said shaft, said shaft being capable of vertical reciprocation with said sleeve and rotatable independently thereof, a turn table secured to said sleeve for rotation in upper and lower positions of said sleeve, a pinion carried by said shaft within said turn table, racks engaging opposite sides 60 of said pinion and guided horizontally on said turn table, article supporting members carried by said racks for extension under articles to be entered into and discharged from the furnace, means for operatively connecting said sleeve to said shaft 65 whereby said turn table may be rotated in unison with said shaft and upon disconnection said shaft alone being rotatable to extend said article supporting members, andmeans for reciprocating said sleeve with said shaft and turn table 70 and for rotating said shaft.

19. In a charging mechanism adapted for use with a hydrogen furnace, an air lock at the furnace opening comprising inner and outer chambers, doors for said chambers, a rotatable ele- 75 .having a plurality of members extensible therefrominto said outer chamber and through the furnace opening into the furnace for operative engagement with untreated material in said outer chamber and treated material in the furnace, and means for simultaneously actuating said members to operatively engage the matc rials, retract the members with the materials into said inner chamber, rotate said element to reverse the materials, actuate said members to enter the reversed materials in the furnace and said louter chamber and thereafter retract the members from the reversed materials and into said inner chamber.-

20. In a charging mechanism adapted for use with a hydrogen material treating furnace having a charging and discharging opening, an air lock at the furnace opening comprising inner and outer chambers, a door between said chambers, an outer door for the outer chamber, a horizontally ymovable bame within the inner chamber at the furnace opening to close the same except when the furnace is being charged and discharged, a charging mechanism operable for charging untreated material from the outer chamber into the furnace and discharging treated material from the furnace into the outer chamber during an operating cycle, operative connections 'between said mechanism and said baille cooperating to cause the baiiie to be moved from the furnace opening during an initial portion of the operating cycle of said mechanism,

said operative connections permitting said battle to be automatically disconnected from said l mechanism and remain stationary during an intermediate portion of the as cycle and during a iinal portion thereof to be automatically connected to said mechanism and moved to close the furnace opening, and means for operating said charging mechanism to complete a cycle of operations.

2l. In a-charging mechanism adapted for use with a hydrogen material treating furnace having a charging and discharging opening, an air lock at the furnace opening comprising inner and outer chambers, a door between said chambers, an outer door for the outer chamber, a rotatable bafile within the inner chamber atl the furnace opening to close the same except when the furnace is being charged and discharged, a

charging mechanism comprising a rotatable, vertically reciproeable element having extensible and retractable members operable for charging untreated material from the outer chamber into the furnace and. discharging treated materiai from the furnace into the outer chamber during an loperating cycle, operative connections between said element and said bafiie cooperating to cause the baule to be moved from the furnace opening during an initial portion of the operating cycle of said mechanism, said operative connections permitting said baiiie to be disconnected from said element by an upward movement of said element and lpermit it to remain stationary during an intermediate portion of the operating cycle and during a nal portion thereof to be moved to close the furnace opening, and means for operating said element and members carried thereby to complete a cycle of operations'.

ALFRED L. DIXON., CARL J. CIN,

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