US2622861A

US2622861A - Rotary hearth furnace

Info

Publication number: US2622861A
Application number: US148457A
Authority: US
Inventors: Randal E Talley
Original assignee: Individual
Current assignee: Individual
Priority date: 1950-03-08
Filing date: 1950-03-08
Publication date: 1952-12-23
Anticipated expiration: 1969-12-23

Description

ROTARY HEARTH F'URNACE Filed March 8, 1950 4 Sheets-Sheet l INVENTOR. faq/.fa 7

R. E. TALLEY ROTARY HEARTH F'URNACE Dec. 23, 1952 4 Sheets-Sheet 2 Filed March 8, 1950 R. E. TALLEY 2,622,86l

4 Sheets-Sheet C5 IN V EN TOR.

m Q w a Dec. 23, 1952 ROTARY HEARTH FURNACE Filed March 8, 1950 Dec. 23, 1952 R. TALLY ROTARY HEARTH FURNACE 4 Sheets-Sheet 4 Filed March 8, 1950 INVENTOR.

Patented Dec. 23, 1952 UNITED STATES PATENT OFFICE ROTARY HEARTH FURNACE Randal E. Talley, Irwin, Pa.

Application March 8, 1950, Serial No. 148,457

8 Claims. l

This invention relates to improvements in industrial heating equipment, more particularly to rotary hearth'heating furnaces with automatic means for charging and discharging the products to be heated. Automatic charging and discharging of rotary furnaces Was first disclosed in Patent No. 1,783,156, granted to me November 25, 1930.

For the purpose of clarity, the invention is illustrated and described as applied for heating steel billets prior to piercing and rolling into seamless steel tubing. This is merely one of the large number of industrial heating processes to which the invention may be applied.

The major components of the present invention comprise in combination, a rotary hearth furnace, a charging machine, a discharge machine and an adjustable sequence Controller for coordinating .the hearth movements with the charging and discharging mechanisms.

In the manufacture of seamless tubing it is essential that the mill be capable of producing the wide variety of sizes of tubing of varying lengths and wall thickness required by the trade. The billets from which the tubes are made like- Wise vary in size and weight.

In passage through the rotary hearth furnace, the larger billets require more hearth space than do the smaller billets. To permit efiicient loading of the hearth, it is therefore essential to coordinate the movement of the hearth with the charging and discharging Operations so as to permit the various sizes of billets to be loaded on the closest permissible hearth spacing. To meet this condition, the hearth drive is arranged to move the hearth progressively forward in a step by step movement, the size of the "step being adjustable to suit the loading requirements of the various sizes of billets.

The matter of l'oading efiiciency is also burdened by the fact that the change from one size billet to another occurs at frequent intervals. Oftentimes the run on a given size billet is not suficient to fill the furnace. To completely empty the furnace and make a fresh start at each change in the hearth spacing is not commercially feasible because the flow of billets to the piercing mill would be interrupted for an extended period between each run. To maintain continuity of operation during such transitory periods, the charging of billets on the new hearth spacing must begin immediately upon completion of the charging of billets at the old hearth spacing, and during the period required for filling the furnace with the new run or runs, the disoharger must continue to function on the old hearth spacing until the previous run is exhausted. To achieve this result the movements of the charger, discharger and hearth are coordinated through the sequence Controller so that in effect the hearth moves forward in Steps of one size for loading and steps of a different size for unloading, while the charger functions in proper sequence with the loading movement of the hearth and the discharger in proper sequence with the unloading movement.

A still further complication arises from the fact that the furnace unit must operate at high speed to keep pace with the piercing mill. Numerous sizes of tubes are produced at a rate of 300 tubes per hour. To keep pace with this rate of production, the furnace unit must deliver a hot billet every twelve seconds. During this twelve second interval the charging machine must complete the cycle of movements required for placing a cold billet in the furnace, the discharge machine must complete a similar cycle of movements in substantially reverse order to remove a hot billet from the furnace, and the furnace hearth must move forward in the required index to match the loading and unloading Operations.

The mass of the moving parts is of such magnitude that lit is physically impossible to attain Operating speeds high enough to permit the required movements to follow one after the other. For example, the moving portion of the charging machine weights approximately 30,000 pounds and to place a cold billet in the furnace its for- Ward and back travel approximates twenty feet in each direction. The weight and travel of the discharge machine is substantially the same. The rotating hearth of the furnace Weighs approximately 1,150,000 pounds and its station to station travel, measured at its periphery, may vary from a minimum of eight inches to a maximum of four feet.

Under the foregong conditions, and with particular reference to mass, time and distance, it will be immediately apparent to those skilled in the art that the required sequence of movements can be consummated in the available time interval only by the development of novel means to supplement commercially available apparatus and controls.

In the accompanying drawings constituting a part hereof, and in which like reference characters designate like parts:

Fig. 1 is a plan view diagrammatically illustrating I the rotary hearth furnace, charging machine and discharge machine;

Fig. 2 a similar view of a sequence Controller;

Fig. 3 is a side elevational view of the sequence controller taken along the line 3-3, Fie. 2;

Fig. 4 is a side elevational view of the sequence controller taken along the line 4-4, Fig. 2;

Fig. 5 is a sectional elevational view of the charging machine and a portion of the rotary furnace;

Fig. 6 is a sectional elevational view of a portion of the furnace and hearth drive mechanism;

Fig. 7 is a sectional elevational view of the discharge machine and a portion of the rotary furnace;

Fig. 8 is a schematic wiring diagram illustrating a control circuit;

Fig. 9 is a view similar to Fig. 1, showing a different pattern of hearth loading; and

Fig. 10 is a plan view, diagrammatically illustrating the sequence controller of Fig. 2 in a different Operating position.

Referring to Fig. 1 of the drawings, the rotary hearth furnace is generally designated by the numeral 1, the charging machine by the numeral 2, the discharge machine by the numeral 3 and the adjustable sequence controller by the numeral 4.

The hearth of the rotary furnace is driven by electric motor 5 through diiferential gear unit 6, the power from which is transmitted through shafts '1 and '1' and chain drives 8 and 8' to reducers 9 and 9', and thence to bevel pinions 10 and 10' which engage bevel gear 11 attached to the under side of the rotary hearth. Hearth drive motor 5 is equipped with solenoid brake 5a to permit quick and accurate stopping of the hearth. The two bevel pinions 1!! and 10' are located diametrically opposite each other and are powered through the differential drive unit 6 to the end that the circumferential thrust required for rotating the hearth is applied equally at two points spaced at 180 degrees and all side thrust thereby eliminated. Further details of the hearth construction and the means employed for its rotatable mounting are shown in Fig. 6. The Vertical support of the hearth is provided by a plurality of rollers 12 and 12' carried on journal bearings 13 which are circumferentially mounted on the furnace foundation in two or more concentric rows. The treads of rollers 12 and 12' engage circular tracks 14 and 14' attached to the underside of the hearth structure. True rolling contact across the tread face of rollers 12 and 12' is attained by tapering the tread and mounting journal bearings 13 with an outward cant so that the axis of the rollers intersects the Vertical axis of the hearth at track level.

-The concentric movement of the hearth in respect to its Vertical a-Xis is maintained by means of rollers 15 carried on journal bearings 16 which are circumferentially mounted on the furnace foundation concentric with the vertical axis of the hearth. The tread face of rollers 15 engage track 1'1 which is attached to the inner circumference of the hearth structure.

To function properly in the manner disclosed, it is essential that the rotating hearth remain flat and concentric. To this end, the main body portion of the supporting steelwork 18 is made strong and rigid with a comparatively weak section of spacer steel 19 mounted above it to support the refractory hearth deck. The spacer steel is loosely mounted to permit free expansion in all directions and is also vented laterally to permit free circulation of the surrounding air. Supporting steelwork 18 is thus freed of the distortive temperature difference normally encountered in conventional hearth structures with the refractory deck mounted directly on the upper face of the main supporting steelwork.

The fiatness and concentricity of the hearth structure is further augmented by circular curb members 20 and 20' which provide lateral curb support for the refractory hearth deck. These two members comprise an integral part of the main hearth support 18. There is no fixed mechanical connection between them and spacer steel 19. The upper portion of curb members 20 and 20' consists of an annular steel trough which is filled with Water and in Cooperation with dependent annular flanges 21 and 2|' serve to seal the clearance gaps 22 and 22' between the moving hearth and the stationary side Walls of the furnace. The water filled annular troughs thus serve the dual purpose of sealng the furnace and providing a strong water cooled structure for holding the hearth flat and concentric.

The lower portion of the furnace side walls in immediate proximity to the rotating hearth deck is made up of wedge shaped tile 23 and 23' circumferentially mounted on similar shaped castings 24 and 24'. Both of these members are exteriorly accessible for replacement or repair without Cooling off or shutting down the furnace.

The horizontal clearance gaps 22 and 22' between the furnace side walls and the rotating hearth are adjustable as to height by means of jackscrews 25 which are built into the foot supports of the annular steel structure which encompasses the brickwork of the heating chamber. These jackscrews also serve to re-level the furnace in the event of unequal settling of the foundations.

Referring to Fig. 5 showing the charging machine, wheel mounted carriage 26 is arranged to move horizontally forward and back on track 2'1, the path of movement being in line with the radial centerline of the charging door of the rotary hearth furnace 1. The carriage is driven by electric motor 28 equipped with solenoid brake 28a to permit quick and accurate control of the stopping positions of the carriage. Power from motor 28 is transmitted through speed reducer 29 to gear 30 which engages rack attached to the carriage. Underslung boom 32 is mounted on the understructure of carriage 2% by means of bell cranks 33 and 33' and slidable collars 34 and 34'. The bell cranks are supported at their fulcrum point by journal bearings 35 and 35' attached to the understructure of the carriage. The load carrying arms of the bell cranks engage the slidable collars through journal bearings 3'6 and 36'. The driven arms of the hell cranks are tied together for movement in unison by connecting rod 31 and journal bearings 38 and 38'. The boom mounting as described provides a pantagraph Suspension for raising and lowering boom 32 by imparting horizontal movement to connecting rod 3'1 and to those skilled in the art it is known that the boom remains horizontal during its up and down movement. Power is imparted to connecting rod 3'1 by means of hydraulic cylinder 39. The body of the hydraulic cylinder is pivotally attached to boom carriage 26 by means of mounting bracket 40, and its piston rod 39a is pivotally attached to connecting rod 31 by means of anchor bracket 4|.

Boom 32 is provided with clamping jaws 32a and 32h arranged to clamp the billets endwise for charging them into the furnace. With this arrangement of the jaws, the billets may be loaded close together on the hearth with resultant improvement in furnace efliciency and output as compared to the results obtainable from conventional boom jaws arranged to clamp the billets crosswise and therefore requiring a wider spacing of the billets on the hearth to permit the crosswise clamping jaws to function.

J aw 32a is attached in fixed position at the inner end of the boom. J aw 32h is slidably mounted on the boom and powered for opening and closing by hydraulic cylinder 42. The body of the hydraulic cylinder is attached to slidable collar 34' and its piston rod 42a is attached to movable jaw 32h. The general construction and operation of the boom and its jaws is the same as a monkey wrench with powered means for opening and closing the movable jaw.

Adjustment of the jaw opening to suit the varying lengths of billets is obtained by means of adjusting screw 43 which is rotatably mounted on boom 32 by means of radial thrust bearings M3 and fii'. The adjusting screw is driven by means of electric motor 45 in conjunction with speed reducer 46, both of which are mounted on the outer end of boom 32. The reactive thrust for shifting the position of boom 32 in respect to slidable support collars 34 and 34', and movable jaw 32h, is supplied by chaser nut 41 in threaded engagement with adjusting screw 43 and nonrotatably mounted in thrust housing 48 which is attached to slidable collar 34'.

The mechanical construction of the discharge machine, Fig. 7, is identical to the charging machine as previously described. Its wheel mounted carriage 119 is arranged to move horizontally forward and back on track 5G, the path of movement being in line with the radial centerline of the discharge door of rotary hearth furnace l.

The functional design of adjustable sequence Controller 4 is shown in sectional plan view Fig. 2, and sectional elevational views Fig. 3 and Fig. 4.

The component parts of the adjustable sequence controller are mounted in steel housing 12 which is provided with hinged covers 12a and 12h to permit ready accessibility for sequence adjustments. The major functional components of the sequence controller consist of

cam cylinders

13 and 14 and their respective engaging pawls 55 and 16.

Cam cylinder 13 controls the hearth spacing of billets being charged into the furnace and is comprised of a plurality of notched cam discs 13a, 13h, 130, etc. secured to shaft 11 which is rotatably mounted in journal bearings 18 and 18'. The number of notches in the cam discs is varied progressively to provide a suitable range of hearth spacings for the various sizes of billets. For example, cam disc 13a may have two notches to provide a hearth spacing of '48 inches; cam disc 13b-three notches for 32" hearth spacing, cam disc 13c-four notches for 24" hearth sp'acing, and so on up to cam disc 13k with twelve notches for 8 hearth spacing. Cam cylinder 14 functions in keeping with the hearth spacing of billets being discharged from the furnace and 'm comprised of a plurality of notched cam discs 14a, 14b, 1llc, etc., secured to shaft 15 which is rotatably mounted in journal bearings il and 80'.

Cam cylinder 14 is identical to cam cylinder 13 except that the cam discs are mounted for rotation in the opposite direction.

Cam cylinder 13 is powered through countershaft Bi which is rotatably mounted in journal bearings 82 and 32' and connected to the slow speed shaft of hearth drive speed reducer 9' by fiexible coupling 83. Gear 84 mounted on countershaft 8| engages gear 85 attached to cam cylinder 13 and thus rotates it proportionately to the movement of the furnace hearth. Cam cylinder 14 is driven by gear B5 of cam cylinder 13 which engages gear 86 attached to 'cam cylinder 14.

Gears

85 and 86 are identical in size, therefore

cam cylinders

13 and 14 rotate at like speeds but in opposite directions.

Pawl 15 is adjustably mounted on pawl shaft 81 and by means of pawl index pin 15a may be positioned to engage any desired cam disc of cam cylinder 13. Pawl 16 is similarly mounted on pawl shaft 89 and by means of pawl index pin 16a may be positioned to engage any desired cam disc of cam cylinder 14. The pawl shafts are mounted for oscillating movement in bearings 88, 38', 90 and 90' and are spring loaded to insure positve engagement between pawl and cam by means of leaf Springs Eil and S2. Tension on the pawl Springs is adjustable by means of adjusting

screws

93 and 94.

Normally closed switch 91 is mounted on housing 12 in operative engagement with actuator lever 95 which is secured to pawl shaft 81. When pawl 15 drops into a notch of the engaging cam disc, actuator lever 95 is depressed and normally closed contact 91a through switch is thereby interrupted. Normally closed switch 98 is similarly mounted and operated by means of actuator lever 96 mounted on pawl shaft 89.

The manner in which the adjustable sequence controller functions in Cooperation with auxiliary controls to attain the stated objects of the invention is disclosed in full detail by the following description of the movements involved and the means employed for producing them. For purposes of clarity the various movements are described as occurring separately. In actual practice, numerous movements occur simultaneously and others substantially overlap. The electrical control devices employed for this purpose, together with their connecting circuits, are diagrammatically portrayed by schematic wiring diagrams, Fig. 8.-

The rate at which billets are discharged from the furnace is controlled by electric time clock 99, the timing interval of which is adjustable to suit the permissible rate of production on billets of various sizes. Confirmation push-button l is a safety switch under manual control of the piercing mill operator. Its function is to prevent automatic delivery of a hot billet by the time clock before the piercing mill is ready to receive it. When the piercing mill is in readiness to receive a hot billet, the operator momentarily closes contact la to arm the time control circuit. This normally occurs prior to the expiration of the timing interval of the time clock but it may occur later with the same ultimate result. In normal operation the operator arms the time control circuit and the time clock completes it. In case of mill delay the time control circuit is armed by the time clock and completed by the operator.

The momentary closing of contact lla energizes relay coil 142 and closes contact llla which serves as an interlock to maintain the circuit through coil |4 2 after contact lfla l is open ed.`

aecasci At the expiration of the interval for which the time clock is set, clock contact 99a closes and clock contact 9gb opens. The closing of contact 99a lights red signal light M6 to indicate that a hot billet is to be delivered. The opening of contact 99h de-energizes relay coil IM, opening contact |44a and closing contact Ifilb. The opening of contact Ilida extinguishes green signal light U25 which burns during the timing interval. The closing o f contact Ilb energizes relay coil M3 and closes contact Ila, thus energizing for- Ward starting coil Iit of motor SI and setting discharge carrier 49 in motion toward the furnace.

The energizing of starter coil Ifi closes interlock contacts IEiSa and Ib, and opens interlock contacts II'IBc, Id and Ie. The opening of contact [060 disarms ureverse starter coil I' for purposes of Safety, The opening of contact ISd disarms the holding circuit of hearth starting relay coil I3'I. The opening of contact Ie deenergizes relay coils M2 and Ifi, to open contacts I'ia and liga. The opening of contact M211 disarms the holding circuit of relay coil U33. The opening of contact iii'ia disarms the making circuit of starter coil I. The closingv of contact Ia maintains the circuit through starter coil I after contact Ia has opened. The closing of contact Iiib energizes relay coil Il to close contacts lola, Ifiii'b and I'id, and to open contact III'Ic. Theopening of contact IWC partially disarms the boom 'up circuit. The closing of contact Iil'ia maintains the circuit through relay coil I'I after contact 5031 has opened. The closing of contact IEI'I'ZJ partially arms the boom down" circuit. The closing of contact I'id arms the making circuit for "clamp relay coil II.

As the discharger moves away from its out position, limit switc I-i attached to track is actuated by switch cam I mounted on carriage 1%9, to close contacts ila and Ib. The closing of contact Ia arms the circuit for discharger reverse starter coil His. The closing of contact Iib energizes relay coil iiI to close contact IlIIa and open contact iib. The opening of contact I-tib partially disarms the boom **down circuit. The closing of contact lilia starts the time clock on its timing interval, opening clock contact 99a and closing clock contact 992). The opening of contact a extinguishes red signal light NG. The closing of contact Sb energizes relay coil Iii to close contact. Iilia and open contact Il'ifiib. The closing of contact Ilifiia lights green signal light I. The opening of contact Ilib disarms the making circuit of relay coil I.

When the discharge boom has moved into the furnace the required distance to properiy index the boom jaws above the billet about to be discharged, the forwardv motion of the discharge carriage is stopped by limit switch Ifil which is mounted on carriage track i for operative engagement with switch cam IG'I mounted on carriage 49. The opening of contact IfTib cie-energizes starter coil iilS to stop the forward movernent of the discharge carriage. The de-energizing of starter coil Ii opens interlock contacts iIlBa and Ib, and closes interlock contacts Ic, IIid and Ii's'e. The opening of contact Ia disarms the holding circuit of starter coil I. The opening of contact Ib disarms the making circuit of relay coil It'l. The closing of contact IOe arms the circuit of "reverse starter coil I09. The closing of contact Itd arms the holding circuit of hearth starting relay coil I3`I. The closing-'of contact Iiiicarms the holding circuit 8 of relay coils I42 and I43. tact I4'Ia energizes relay coil IH to closecontact IIIa and open contact IIIb. The opening of contact IIIb disarms the boom upcircuit for safety purposes. The closing of contact I I Ia energizes solenoid Valve "down" coil IOI to admit fluid to hydraulic cylinder 62 for lowering boom 55 to clamping level.

As the boom leaves its "up position, limit switch I5I attached to carriage 49 is actuated by switch cam I66 attached to connecting rod 60. The opening of contact Ila cie-energizes relay coil I I2 to open contacts II2a and I I2b and close contact II2c. The opening of contacts II2a and II2b disarms the discharge carriagel startingv cir-l cuits for purposes of safety. The closing of con'- tact II2c arms the circuit for time delay relay.

coil IIG. The closing of contact I5Ib arms the boom "up" circuit. When the boom reaches its downi7 position, limit switch ISO attached to carriage 49 is actuated by switch cam ISB attached to connecting rod 6B. The opening of contact Ib de-energizes relay coil III, opening contact IIIa and closing contact IlIb. The opening of contact IIIa de-energizes solenoid valve "down coil IEII. The closing of contact IIIb arms the boom uupH circuit. The closing of contact I50a energizes relay coil IIO to close contacts Ila and IIIib. The closing of contact IIGb serves no purpose during this movement. The closing of contact IIJa energizes relay coil IM to close contacts Illia, lIb, Illic, Illid, Ilde and I Mg, and to open contact I I4. The closing of contacts IIia, II4b and IIfiic sets up their respective circuits for subsequent movements.

Contact IIlId serves as an nterlock to maintain the circuit through relay coil II after its making circuit has opened. The openingv of contact IIli de-energizes relay coil I I to open contacts II5a, Iib, IIc, IId and IIEe, and to close,

contact II. The opening of contact II5a disarms "forward starter coil m6. of contact I Ib de-energizes relay coil I'I to open contacts I'a, IB'Ib and Iilld, and to close contact I'ic. The opening of contact lEi'Ia disarms the holding circuit of relay coil IO'I. The opening of contact It'lb partially disarms the boom udown circuit. The closing of contact I'Ic partially arms the boom uup circuit. The opening of contact Ili'id disarms the making circuit of f'clamp relay coil IM. The opening of contact I I5c partially disarms the boom "up" circuit.

The opening of contact II5d disarms the holding circuit of 'unclarnp" relay coil II5. The closing of contact II5 arms the holding circuit of "clamp relay coil III. The opening of contact IIEe de-energizes solenoid valve "unclamp coil Iili. The closing of contact II4e energizes solenoid valve '*clamp" coil U33 to admit fluid to hydraulic cylinder 65 to close the boom jaws.

As the boom jaws start to close, limit switch I52 attached to carriage 49 is actuated by switch cam I attached to movable jaw 55b to open contact Ia and partially disarm the boom "up circuit. The closing of contact iIf-ig energizes adjustable time delay relay coil IIE to close contact*l Il6a after sufiicient time has elapsed to permit the boom jaws to close and grip the billet. The closing of contact I Iiia energizes relay coil I I3 to close contact I |3a and open contact II3b. The opening of contact II3b disarms the boom "down" circuit for purposes of Safety. The closing of contact II3a energizes solenoid valve up coil I2 to raise the boom. As the boom leaves its "down" position, limitl switch I50 isactuated to The closing of con- The openingA open contact |5Ila and close contact Ib. The opening of contact Ia de-energizes relay coil III] to open contacts I I a and I IOb. The opening of contact IIIla disarms the making circuit of clamp relay coil II4. The opening of contact IIOb disarms the making circuit of "unclamp relay coil II5. The closing of contact Ib arms the boom "down circuit. When the boom reaches its "up position, limit switch I is actuated by switch cam I to close contact I5Ia and open contact I5Ib. The opening of contact I5Ib de-energizes relay coil II3 to open contact II3a and close contact II3b. The opening of contact II3a de-energizes solenoid Valve boom up coil IU. The closing of contact II3b arms the boom down circuit. The closing of contact I5la energizes relay coil II2 to close contacts II2a and II2b and open contact II2c. The opening of contact II2c de-energizes time delay relay coil II. The closing of contact I Iza serves no purpose during this movement. The closing of contact II2b energizes "reverse starter coil lll9 of motor 5| to set discharge carriage 49 in motion away from the furnace.

The energizing of starter coil E69 opens interlock contact Iflfm and closes interlock contact Ill9b. The opening of contact I lilia disarms forward starter coil IM for purposes of safety. The closing of contact IOQb energizes relay coil N18 to close contacts Illa, Illb and I08d, and to open contact Illtc. The closing of contact IllBa maintains the circuit through relay coil m8 after contact IIiQb has opened. The closing of contact Ib partially arms the boom "down" circuit. The closing of contact I Mid arms the making circuit for "unclamp relay coil I I 5. The opening of contact IBc serves no purpose during this movement.

The initial outward movement of the discharge carriage actuates limit switch IM to open contact I4'I`a and close contact I4`Ib. The opening of contact I'lla partially disarms the boom "down circuit. The closing of contact Mlb arms the discharger "forward starting circuit.

When the discharge carriage reaches its "out position, limit switch M59 is actuated to open contacts Mila and Ififib. The opening of contact ltga de-energizes 'reverse starter coil Ill!! to stop the carriage. The de-energizing of starter coil IIlS closes interlock contact Ia and opens interlock contact Ib. The closing of contact Illa arms the dscharger nforward starter circuit. The opening lof contact Iilb disarms the making circuit of relay coil IIBB.

The opening of contact M91) de-energizes relay coil Ill to open contact ItIa and close contact IMZ). The opening of contact Mia clears the time clock circuits and places its controls in readiness for nauguration of the succeeding discharge operation upon completion of its timing interval. The closing of contact I4Ib energizes relay coil I I I to close contact I I Ia and open contact IIIb. The opening of contact III b disarms the boom up circuit for safety purposes. The closing of contact IIIa energizes solenoid Valve udown coil IBI to lower the boom.

The initial downward movement of the boom actuates limit switch E5! to open contact I 5Ia and close contact iElIb. The opening of contact I5Ia de-energizes relay coil II2 to lopen contacts I I2c and I Izb, and close contact I i2c. The opening of contacts 2a and IIZb disarms the discharge carriage starting circuits for purposes of Safety. The closing of contact IIc serves no purpose during this movement. The closing of ment. The closing of contact IIOb energizes relay coil II5 to close contacts II5a, IIb, II5c, II5d and II5e, and to open contact II5. 'The closing of contacts lla, II5b and II5c sets up their respective circuits for subsequent move'- ments. The closing of contact II5d provides an interlock to maintain the circuit through relay coil I l5 after its making circuit has opened. The opening of contact II5 de-energizes relay coil II4 to open contacts II-ia, IIib, IMc, Iltd, III'e and IMg, and to close contact IM. The opening of contact II 4a de-energizes relay coil IIlil to open contacts lIlBa, Iilb and Illd, and to close contact Ill8c. The opening of contact I disarms the holding circuit of relay coil IIlB. The opening of contact I 98h partially disarms the boom "down circuit. The opening of contact losd disarms the making circuit of "unclamp relay coil II5. The closing of contact Ic partially arms the boom "up" circuit. The opening of contact I Mb disarms 'i'everse" starter coil I 09. The opening of contact Ilc partially disarms the boom "up circuit. The opening of contact I Illcl disarms the holding circuit of "clamp relay coil II4. The opening of contact lite de-energizes solenoid valve "clamp coil IIl3. The opening 'of contact I Mg serves no purpose during this movement. The closing of contact I I4 arms the holding circuit of "unclamp relay coil I I5. The closing of contact I I5e energizes solenoid valve *'unclamp coil m4 to open the boom jaws and release the hot billet for delivery to the piercing mll by auxiliary conveying means which is not a component of this invention.

At the end of the uunclamp stroke of hydraulic cylinder 65, limit switch IZ mounted on carriage 49 is actuated by switch cam I65 attached to movable jaw 55h. The closing of contact I52a energizes relay coil II3, closing contact II3a and opening contact IISb. The opening of contact II3b disarms the boom 'down circuit for purposes of safety. The closing of contact IIa energizes solenoid Valve f'up coil I 92 to raise the boom. As theboom leaves its Udown position, limit switch I50 is actuated to open contact IBUa and close contact I5Ilb. The opening of contact Ia de-energizes relay coil I Ill to open contacts IIfIa and Illlb. The opening of contact IIIla disarms the making circuit of clamp relay coil IIfl. The opening of contact IIUb disarms the making circuit of unc1amp relay coil II5. The closing of contact I5Ilb arms the boom "down circuit. When the boom arrives at the "up position, limit switch I 5| is actuated to close contact I5Ia and open contact I5Ib. The opening of contact I5Ib de-energizes relay coil II3 to open contact I I3a and close contact I I3b. The opening of contact II3a de-energizes solenoid valve boom *'up coil I02. The closing of contact 'I I3b arms the boom "down circuit. The closing of contact I5Ia energizes relay coil Il2, closing contacts I I 2a and I I2b, and opening contact I I2c. The closing of contact II2b and the opening of contact IIZc serve no purpose during this movement. The closing of contact 2a arms the circuit through starter coil IOG, thu's com'pleting one sequence of movements by the discharge machine and 'placing the controls in readiness for inauguration of the succeeding discharge operation when signalled by the time clock.

The hearth now moves forward and stops at the next succeeding station. Depending on the spacing of the billets on the hearth, this may be a charging station, a discharge station or a station at which both charging and discharging oocur.

With the sequence controller set for charging and discharging on the same hearth spacing, the charger and discharger both function at each stop. When Operating in this manner. the hearth is started by the discharger and stopped by the sequence controller as hereinafter described.

With the sequence controller set for operation on unequal stations, the hearth is started by either the charger or the discharger and. stopped by the sequence controller at the next succeeding station to move into index for either charging or discharging. It is to be noted that during operation on unequal hearth spacing, at periodic intervals a charging station and a discharge station Will move into index concurrently. When this occurs, the sequence controller functions as though it were |set for equal stations and the next succeeding movement of the hearth is initiated by the discharger. For example, if the oharging spacing is double the discharge spacing, the charger and discharger function concurrently at each alternate stop 'and the discharger functions alone at the intermediate stop. For hearth spacings involving fractional ratios such as 5 to 3, a charging 'station and a di-scharge station move into index concurrently at each seventh stop of the hearth'and the six intermediate stations move into index'non-concurrently.

When the hearth is stopped by the sequence controller at a non-concurrent station for charging, the succeeding hearth movement is initiated by the charger, the starting impulse being supplied by one-way limit switch I, which is actuated by switch cam 162 after the charger has delivered its cold billet and has started to move away from the furnace. The actuation of limit switch |54 momentarily closes contact l54a and momentarily opens contact I54b. The opening of contact |54b de-energizes relay coil |33 to open contacts I33a and l33b. The opening of contact |33a disarms charger "fiorward starter coil I 22. The opening of contact |33b disarms the maintaining circuit for relay coil |33. The closing of contact I 54a energizes time del ay relay coil 139 to close contacts |39a and |39b. The closing of contact |39b maintains the circuit through relay coil 139 after contact Ia has opened. The closing of contact 1391i energizes starter coil l35 to set the hearth in motion. As the hearth starts to move, contact 91a of the sequence controller closes, and energizes relay coil M0 to close contacts Mflb, Ideo and ldd, and to open contacts I 40a and Mile. The opening of contact Ma disarms charger' *'forward" starter coil |22. The closing of contact lllb energizes relay coil |33 to close contacts |33a and |33b. The closing of contact |33a arms charger "forward" starter coil |22. The closing of contact |33b maintains the circuit through relay coil |33 after contact |40b has opened. The closing of contact |40c arms the discharger actuated making circuit -for hearth starter coil 135. The closing of contact |40d completes the holding circuit fo'r continuing the. hearth in motion after contact |39a has opened. The opening of contact |4De de-energizes time delay relay coil [39 to open contacts l39a and |39b. The opening of contact |39b disarms the holding circuit of time delay relay coil |39. The opening of contact la disarms the charger actuated making circuit for hearth starter coil |35. The opening of contact |3Sa is momentarily delayed to insure that the holding circuit is completed by the closing of contact Itild before the making circuit is interrupted. The hearth continues in motion until it is stopped by the sequence controller at the next succeeding station in the manner hereinafter described.

When the hearth is stopped by the sequence controller at a non-concurrent station for discharging, the succeeding hearth movement is initiated by the discharger, the starting impulse being supplied by one-way limit switch M8 which is actuated by switch cam l'l after the discharger picks up its hot billet and has started to move away from the furnace. The actuation of limit switch M8 momentarily closes contact |48a to energize time delay relay coil |31 to close contacts |31a, l3'lb and |3'lc. The closing of contact [31h maintains the holding circuit through relay coil |31 after its making circuit has opened. The closing of contact l3'lc serves no purpose during this movement. The closing of contact |3'la energizes starter coil |35 to set the hearth in motion. As the hearth starts to move, contact 98a of the sequence controller closes and energizes relay coil |38 to open contacts |38a and |38d, and close contacts 138D and 1380. The opening of contact [38a disarms discharger forward starter coil [06. The closing of contact |38b arms the charger actuated making circuit for hearth starter coil |35. The closing of contact l38c completes the holding circuit for continuing the hearth in motion after contact l3'la of the making circuit has opened. The opening of contact |38d deenergizes time delay relay coil |3'l to open contacts |31a, l31b and |31c. The opening of contact |3'lb disarms the holding circuit of time delay relay coil |31. The opening of contact |31c serves no purpose during this movement. The opening of contact |31a disarms the discharger actuated making circuit for hearth starter coil 105. The opening of contact |3'la is momentarily delayed to insure that the holding circuit is completed by the closing of contact |3Bc before the making circuit is interrupted. The hearth continues in motion until it is stopped by the sequence controller at the next succeeding station in the manner hereinafter described.

When the hearth is stopped by the sequence controller at a concurrent station for charging and discharging, the succeeding hearth movement is initiated by the discharger. This applies whether the sequence controller is set for operation on equal stations as shown in Fig. 10 or on unequal stations as shown in Fig. 2. When the hearth stops at a concurrent station, the charger starts immediately and normally completes its function ahead of the discharger which must await its signal from the time clock. It is therefore essential to defer starting the hearth until the outgoing hot billet has been gripped by the discharger boom jaws and lifted clear of the hearth. In the accomplishment of this result, the sequence controller and its auxiliary controls function in the following manner. When the hearth arrives at a concurrent station, pawls 113'1a arms the discharger actuatedr making '15 and '18 fall simultaneously into the engaging notches of their respective cam discs. Contacts 91a and 98a are thus opened simultaneously to de-energize

relay coils

138 and 140, opening contacts 13827, 1380, 14111), 1400 and 14m1, and closing contacts 13811, 138d, 14011 and 1408. The opening of contacts 138c and 140d de-energizes starter coil 135 and stops the hearth. The opening of contact 140c disarms the discharger actuated hearth starting circuit. The opening of contact 1381 disarms the charger actuated hearth starting circuit. The opening of contact 140b and the closing of contact 1408 serve no purpose during this movement. The closing of contact 138d arms the holding circuit for relay coil 13'1. The closing of contact 14011 sets the charger in motion but the closing of contact 154a during its outward travel does not start the hearth as nreviously described in respect to non-concurrent operation because contact 13th of the Charger actuated hearth starting circuit is open.

Upon termination of the timing interval, the discharger is set in motion by the time clock and a discharge operation is completed in the manner previously described. When the discharger has picked up its hot billet and has started to move away from the furnace, limit switch 148 is actuated to momentarily close contact 148a. The closing of contact 1480i energizes time delay relay coil 131 to close contacts 13'1b and 1310. The closing of contact circuit of hearth starter coil 135. The closing of contact 131b maintains the holding circuit through time delay relay coil 131 after its making circuit has opened. The closing of contact 1310 energizes relay coil 140 to open contacts Mila and 1406, and to close contacts 1491, 14130 and 14011. The opening of contact Mila disarms the charger uforward starting circuit. The closing of contact 140b energizes relay coil 133 to close contacts 13311 and 1331. The closing of contact 13311, arms Charger "forward starter coil 122. The closing of contact 1331)` maintains the circuit through relay coil 133 after contact 1407) has opened. The closing of contact 140z arms the holding circuit for hearth starter coil 135. The opening of contact 1498 disarms the holding circuit for time delay relay coil 139. The closing of contact 1400 energizes starter coil 135 to set the hearth in motion.

As the hearth starts to move` contact 98a of the seouence controller closes and energizes relay coil. 138 to onen contacts 138a and 138d, and close contacts 138D and 1380. The opening of contact 1386i disarms the discharger "forward starting circuit. The closing of contact 138i) arms the Charger actuated" making circuit for hearth starter coil 135. The closing of contact 1350 completes the holding circuit for continuing the hearth in motion after contact 13'1a of the making circuit has opened. The opening of contact 138z de-energizes time delay relay coil 13'1 to open contacts 13`1a, 13'1b' and 13`1c. The opening of contact 137i) disarms the holding circuit for time delay relay coil 13'1. The opening of contact 13'10 serves no purpose during this movement. The opening of contact 13'1a disarms the discharger actuated making circuit for hearth starter coil 135. The opening of contact 13'1a is momentarily delayed to insure that the holding circuit is completed by the closing of contact 138c before the making circuit is interrupted.

The hearth continues in motion until it is stopped by the sequence controller at the next succeeding station in the manner hereinafter described.

Irrespective of whether the hearth has been set in motion by the charger or discharger as previously described, it is stopped by the sequence controller in proper index at the next succeeding station, which may be a non-concurrent charging station, a non-concurrent discharge station or a concurrent station for both charging and discharging.

When the sequence Controller presents a nonconourrent" notch in cam cylinder 14 into which its mating pawl '1G can fall, the hearth is stopped at a discharge station by the opening of contact 98a which de-energizes relay coil 138 to open contacts 138i) and 1380, and to close contacts 13811 and 138d. The opening of contact 13817 disarms the Charger actuated making circuit for hearth starter coil i35. The closing of contact 13803 arms the holding circuit for time delay relay coil 131. The opening of contact 1380 de-energizes starter coil and stops the hearth. The closing of contact 1380i arms the discharger forward starting circuit, thus placing the controls in readiness for the discharge operation to follow upon signal by the time clock.

When the sequence Controller presents a nonconcurrent notch in cam cylinder '13 into which its mating pawl T5 can fall, the hearth is stopped at a charging station by the opening of contact ela which de-energizes relay coil 141i to close contacts i'iila and llie, and to open contacts 14%,14iid and Iflc. The closing of contact 1408 arms the holding circuit for time delay relay coil 135. The opening of contact Mb disarms the making Circuit for relay coil 15:23. The opening of contact Iic disarms the discharger actuated making circuit for hearth starter coil 135. The closing of contact Iflc energizes starter coil 122 to initiate a cycle of operation by the Charger as hereinafter described.

When the sequence controller concurrently presents a charging notch and a discharge notch into which pawls 'E5 and '16 can fall, contacts 97a and 98a are opened simultaneously to de-energize relay coils 138 and Hit, thus opening contacts ilb, 138c, ifiiib, 14130 and Md, and closing contacts ifala, 13m, lla and 1408. The opening of contacts 9380 and 1400i de-energizes starter coil 135 to stop the hearth. The closing of contact 13m arms the discharger uforward starter circuit for subseqnent initiation of the discharge operation by the time clock. The closing of contact Illia energizes charger uforward starter coil 1'22 to initiate a cycle of operation by the charger as hereinafter described. The balance of the contacts affected by the de-energizing of relay coils 38 and Mii function the same as at nonconcurrent hearth stops as previously described.

When the hearth stops at a charging station. either concurrent or non-concurrent, the sequence Controller functions as previously described to set the charger in motion by the closing of contact Ifa. The ensuing sequence of movements by the functional components of the Charger are attained in the following manner.

The closing of contact ida energizes starter coil 122 to start motor 2a and set the charger in motion toward the furnace. moves away from the '*out" position, limit switch 15'5 attached to track 2'1 is actuated by switch cam 163 attached to carriage 26. The opening of contact 1550i partially disarms the boom As the Charger -i holding circuit for relay coil 130.

1.5 V''down circuit. The closing of' contact 11552) arms the: Charger ureverse starter circuit. The energizing of starter coil 122 closes interlock contact 1220J and opens interlock contacts 1221) and 122c. The opening of contact 122i) disarms the charger *'1'everse starter circuit for purposes of safcty. The opening of contact 122c disarms the holding Circuit of hearth starting relay coil 139. The closing of contact 122a energizes relay coil 124 to close contacts 12lia, 1241) and 12m1, and to open contact 1240. The closing of contact 1241r maintains the circuit through relay coil 121i after contact 12211 has opened. The closing of contact 1241 partially arms the boom "down circuit. The opening of contact I'Mc partially disarms boom "up" circuit. The closing of contact 124d arms the making circuit for unclamp relay coil 1311.

When the chai'ger has moved forward to properly position its cold billet above the hearth,

limit switch 153 attached to track 2'1 is actuated by switch cam 162 attached to carriage 26. The opening of contact 153i) de-energizes starter coil 122 to stop the charger. The closing of contact 153a energizes relay coil 12'1, closing contact 12'1a and opening contact 12'1b. The opening of contact 12'1b disarms the boom "up circuit for safety purposes. The closing of contact 12'1a energizes solenoid "down" coil 11'1 to admit fiuid to hydraulic cylinder 39 for lowering boom 32 to unclamping level. As the boom leaves its up position, limit switch '1 attached to carriage 26 is actuated by switch cam 16B attached to connecting rod 3'1. The closing of contact 15% arms the boom "up" circuit. The opening of contact 1511r deenergizes relay coil 128 to open contacts 128a and 128D and close contact 1280. The opening of contacts 128a and 128D disarms the Charger starter circuits for purposes of Safety. The closing of contact 128c serves no purpose during this movement.

When the boom reaches its "down position, limit switch 158 attached to carriage 2B is actuated by switch cam 160 attached to connecting rod 31. The opening of contact 15% cie-energizes relay coil 121 to open contact 12'1a and close contact 12'1b. The opening of contact 12'1a deenergizes boom "down solenoid valve coil 11'1. The closing of contact 12'1b arms the boom "up" circuit. relay coil 12'6 to close contacts 12Sa and 1261). The closing of contact 126D serves no purpose during this movement. The closing of contact 126a. energizes relay coil 130 to close contacts 13m, 13th, 1350, 131ld and 1311, and to open contact 130c. The closing of contacts 13201,, 13027 and 139 sets up their respective circuits for subsequent movements. Contact 130d serves as an interlock to maintain the circuit through relay coil 130 after its making circuit has opened. The opening of contact 13m1 de-energizes relay coil 131 to open contacts131a,131b,131c,131d, 131 and 131g, and to close contact 131a. The opening of contacts 131a, 131b and 131d sets up their respective circuits for subsequent movements. The opening of contact 131 disarms the holding circuit of relay coil 131. The opening of contact 131g serves no purpose during this movement. The closing of contact 131a completes the The opening of contact 131c de-energizes solenoid valve 'fclamp" coil 120. The closing of contact 1300 energizes solenoid valve "unclamp" coil 1 19 to ad- Vmit fiuid to hydraulic cylinder 42 to open the The closing of contact 1550!, energizes T16 boom jaws and' deposit the eold'blllet'on the hearth.

As the boom jaws arrive at the "open" position, limit switch 158 attached to carriage 26 is actuated by switch cam 161 attached to boom jaw 32D, thus closing contact 158a and energizing relay coil 129 to close contact 129a and open contact 1291). The opening of contact 129b disarms the boom "down circuit for safety purposes. The closing of contact 12911 energizes solenoid valve '*up coil 118 to admit fiuid to hydraulic cylinder 39 for raising the boom. As the boom leaves its "down position, limit switch 156 is actuated to open contact 156a and close contact 15th. The closing of contact 156D arms the boom udown circuit. The opening of contact 15611 de-energizes relay coil 12'6 to open contacts 12611 and i). The opening of contact 12611 serves no purpose during this movement. The opening of contact 1262 partially disarms the "clamp relay circuit. As the boom arrives at its "up" position, limit switch 15'1 is actuated by switch cam M50 to close contact 15'1a and open contact 15'1b. The opening of contact 15'1b de-energizes relay coil 129 to open contact 129a and close contact 1291. The opening of contact 129a de-energizes boom "up" solenoid valve coil 118. The closing of contact 129D arms the boom "down circuit. The closing of contact 15'1a energizes relay coil 128 to close contacts 128a and 128b and open contact 1280. The closing of contact 128a serves no purpose during this movement. The opening of contact 1280 disarms time delay relay coil 132. The closing of contact 128b energizes ureverse starter coil 125 of motor 28 to set the charger carriage in motion away from the furnace. As the Charger moves away from its "in" position, limit switch 153 is actuated to open contact 153a and close contact 1531). The opening of contact 153a partially disarms the boom "down" circuit. The closing of contact 153b arms the charger 'in starter circuit.

The energizing of starter coil 125 opens interlock contact 125a and closes interlock contact 1251. The opening of contact 125a disarms for- Ward starter coil 122 for safety purposes. The closing of contact 125b energizes relay coil 123 to close contacts 123a, 123D and 123d, and to open contact 123c. The closing of contact 123a maintains the circuit through relay coil 123 after contact 125i) has opened. The closing of contact 1231) partially arms the boom "down circuit. The opening of contact 1230 partially disarms the boom "up circuit. The closing of contact 123d partially arms the "clamp" relay circuit. When the Charger carriage reaches its "out" position, limit switch is actuated to close contact 1551r and open contact 155D. The opening of contact 15517 de-energizes reverse starter coil 125 to stop the carriage in the "out position. The closing of contact 155a energizes relay coil 12'1 to close contact 12'1a and open contact 12'1b. The opening of contact 12'1b disarms the boom nup circuit. The closing of contact 12'1a energizes solenoid valve udown" coil 1 1'1 to lower the boom to clamping level.

As the boom leaves its up position, limit switch 151 is actuated to open contact 15'1a and close contact 1511. The closing of contact 15'1b arms the boom l'up'' circuit. The opening of contact 15111 de-energizes relay coil 128 to open contacts `128a and 123b, and to close contact 1288. The opening of contacts |28a and 128b disarms the charging starter circuits for purposes aeeaeci .of safety. The closing of contact l2'8c arms the circuit for time delay relay coil l 32.

When the boom reaches its "down position, limit switch l56 is actuated to close contact lta and open contact l56b. The opening of contact l56b de-energizes relay coil l2'l to open contact l2'la and close contact l2'lb. The opening of contact l2'la de-energizes boom udown solenoid valve coil I l'I. The closing of contact l2'lb arms the boom "up" circuit. The closing of contact l56a energizes relay coil l26 to close contacts l26a and l26b. The closing of contact lta serves no purpose |during this movement. The closing of contact l26b energizes relay coil i3l to close contacts l3la, l3lb, l3lc, lld, l3l and l3lg, and to open contact l3le. The olosing of contacts l3la, l3lb and l3ld sets up their respective circuits for su'bsequent movements. Contact l3l serves as an interlock to maintain the circuit through relay coil l3l after its making circuit has opened. The opening of contact l3le de-energizes relay coil l3l] to open contacts llla, l3llb, l3lJc, l30d and l3lJ, and to close contact liwe. The opening of contact l3llb disarms the charger '*reverse starting circuit. The opening of contact .l3c de-energizes solenoid valve "unclamp coil ll9. The opening of contact l3d disarms the holding circuit for, unclamp relay coil l30. The closing of contact 'Eflc arms the holding circuit for "clamp relay coil 13|. The opening of contact l30 partially disarms the boom "up circuit. The opening of contact l3lia de-energizes relay coil l23 to open contacts lZa, l23b and 1230i, and to close contact l23c. The opening of contact l23a disarms the holding circuit for relay coil l23. The opening of contact l23b partially disarms the boom down'7 circuit. The closing of contact l23c partially arms the boom "up circuit. The opening of contact l23d disarms the making circuit for Hclamp" relay coil l3l. The cl-osing of contact lt lc energizes solenoid Valve '*clamp coil l2ll to admit fiuid to hydraulic cylinder 42 for closing the boom jaws to clamp a previously positioned cold billet for the next succeeding charging operation.

Various means for moving the incoming cold billets successively into clamping position are well known to those skilled in the art and are not included as a component of this invention. Flag switch leg is employed as a safety feature to prevent any possible confiict of movements in respect to the incoming cold billet and the boom jaws. When .the cold billet has moved into clamping position, fiag switch l59 is actuated by the billet to close contact l59a and thus arm the boom "down circuit for lowering the boom by the closing of contact l55a as previously described. In case the movement of the billet into clamping position is delayed, the closing of contact l55a arms the boom "down circuit and the subsequent movement of the cold billet into clamping position closes contact [59a and lowers the boom.

The closing of contact l3 lg energizes adjustable time delay relay coil l32 to close contact l32a after suiiicient time has elapsed for the boom jaws to close and grip the billet. The closing of contact E3204 energizes relay coil l29 to close contact lila and open contact l29b. The opening of contact l29b disarms the boom Udown circuit for purposes of safety. ,The closing of contact la energizes solenoid valve Uup coil ll, admitting fluid to hydraulic cylinder 39 to raise Athe boom and its clamped cold billet to the upposition. As the boom leaves its f'down" position, limit switch l56 is actuated to open contact l56a -and close contact l56b. The closing of contact l56b arms the boom "down circuit. The opening of contact l56a de-energizes relay coil |2'e' to open contacts l26a and lZtb. The opening of contact l26a disarms the making circuit for "unclamp relay coil l3l). The opening of contact l26b serves no purpose during this movement." As the boom arrives at the up position, limit switch l'l is actuated to close contact |5'la, and open contact l5`lb. The opening of contact l'lb de-energizes relay coil l29 to open contact l29a and close contact l29b. The opening of contact l29a de-energizes boom "up solenoid valve coil ll8. The closing of contact l29b arms the boom "down circuit. The closing of contact li'a energizes relay coil l28 to close contacts lilia and l28b, and to open contact l28c. The opening of contact l28c de-energizes time delay relay coil l32. The closing of contact l28b serves no purpose during this movement. The closing of contact l28a arms the "forward starting circuit of Charger motor 28, .thus completing one cycle of operation by the charger and placing its control circuits in readiness for initiation of the subsequent charging cycle upon signal from the sequence controller.

For purposes of clarity, the plurality of movements involved in the functioning of the invention are hereinbefore described as occurringseparately. In actual practice, each signal by the time clock initiates a sequence of movements which continue Without interruption until all of the movements required to satisfy the existing leading pattern have been completed. In each case the sequence begins When the discharger is set in motion by the time clock and ends when the next succeeding hot billet moves into index with the discharge door. The intervening movements are fixed by the loading pattern and consummated by the sequence Controller. In concurrent" operation as portrayed by Fig. 10, the sequence is comprised of one movement each by the Charger, discharger and hearth, and is com- :pleted at each stop of the hearth. In non-concurrent" operation as portrayed by Fig. 2, if the charging spacing is less than the discharge spacing, the charger and the hearth may execute two or more intervening movements before the succeeding hot billet moves into discharge index to complete the sequence. Or conversely, if the charging spacingis larger than the discharge s-pacing, the sequence may be completed without any intervening movements by the Charger.

All of the foregoing Operatingsequences are automatically attained by the controls as illustrated and described. The only manual adjustment involved is the setting of the sequence controller to the required hearth spacing.

While I have described my invention as embodied in concrete form and as Operating in a specific manner in accordance With the provision of the patent statutes, it is to be understood that I do not limit my invention thereto, since various modifications thereof will suggest themselves to those skilled in the art Without departing from the spirit of the invention.

I claim:

1. In a rotary hearth furnace, a rotatable hearth, a drive mechanism for rotating said hearth to advance said hearth in steps of predetermined distances, charging mechanism for delivering articles to be heated into the furnace chamber and clepositing the same on said hearth, discharging mechanism for removing the heated 19 articles from said hearth and witlidrawing the same from the furnace chamber, and a selector mechanism for cooi'dinating the movements of the charging and discharging mechanisms independently of each other with different step-bystep movements of the hearth.

2. In a rotary hearth furnace, a rotatable hearth, a drive mechanism for rotating said hearth including an electric motor, a selector mechanism operable in response to rotary movement of the hearth for stopping the hearth movernent at predetermined distances of hearth travel, charging mechanism for loading articles to be heat-ed on said hearth, discharging mechanism for unlcading the heated articles from said hearth, electrically energized Operating mechanisms for the charging and discliarging mechanisms including a time clock controlling the operation of said dischargingmechanism, and means operable by said discharging mechanism for energizing the hearth drive mechanism.

3. In a rotary hearth furnace, a rotatable hearth, a drive mechanism for rotating saii hearth including an electric motor, a selector mechanism operable in response to rotary movement of the hearth for stopping the hearth movement at predetermined distances of hearth travel, charging mechanism for loading articles to ,be heated on said hearth, discharging mechanism for unloading the heated articles from said hearth. electrically energized Operating mechanisms for the charging and discharging mechanisms including a time clock controlling the operation of said discharging mechanism, means operable by said discharging mechanism for energizing the hearth drive mechanism, and means operable by said selector mechanism for energizing said charging Operating mechanism.

4. In combination, a movable conveyor, a charging mechanism for loading articles on said conveyoi', a discharge mechanism for unloading said conveyor, drive means for said conveyor, Operating mechanisms for said charging and discharging mechanisms, means operable in response to movement of said conveyor for integrating the conveyor movements into predetermined station stops for both the loading and unloading of articles from said conveyor independently of each other, a time clock controlling the operation of said discharge mechanisin, and means operable by said discharge mechanism for energizing said conveyor drive mechanism.

5. In a rotary hearth furnace, a rotatable hearth, 'a drive mechanism for rotating said hearth including an electric motor, a selector mechanism operable in response to rotary movement of the hearth for stopping the hearth movement at predetermined distances of hearth travel, charging mechanism for loading articles to be heated on said hearth, discharging mechanism for unloading the heated articles from nald hearth, electrically energized Operating mechanisms for the charging and discharging mechanisms including a time clock controlling he operation of said discharging mechanism, and means operable by said discharging mechanism for energizing the hearth drive mechanism, said selector mechanism comprising a pair of cam cylinders, a counter-shaft for driving said cam cylinders operably connected to the hearth drive, a plurality of cam discs mounted on said cam cylinders, said discs being provided with angularly spaced notches, the number of notches of a particular disc determining the hearth spacings for different station stops, cam pawls for engaging the notches in the cam discs for actuating a control switch for deenergizing the hearth drive motor when a pawl drops into a cam notch, said pawls being mounted to be adjustable over the full range of adjacent discs whereby the pawl cooperating with one row of discs of a cam cylinder may be adjusted to effect hearth spacings independently of the setting of the pawl on the other of said'pair of cam cylinder discs.

6. In a rotary hearth furnace, a rotatable hearth, a drive mechanism for rotating said hearth including an electric motor, a selector mechanism for stopping the hearth movement at predetermined distances of hearth travel, charging mechanism for loading articles to be heated on said hearth, discharging mechanism for unloading the heated` articles from said hearth, electrically energized Operating mechanisms for the charging and discharging mechanisms including a time clock controlling the operation of said discharging mechanism, and means operable by said discharging mechanism for en'ergizing the hearth drive mechanism, said selector mechanism comprising a pair of cam cylinders each consisting of a plurality of cam discs having angularly spaced notches, the notches in each disc of a row of discs varying in number in accordance with the range of hearth spacing desired, means for rotating said cam cylinders coordinately with the rotation of the furnace hearth, cam pawls for engaging the notches of the cam discs whereby the hearth drive motor is deenergized to stop the hearth, one of said cam cylinders functioning to integrate the hearth movements into predetermined station stops for loading the hearth, and the other of said cam cylinders being independently operable for integrating the hearth movements into predetermined station stops for unloading the articles from the hearth.

7. In a rotary hearth furnace for heating billets, a rotatable hearth, a drive mechanism for rotating said hearth, charging mechanism for loading billets with their axes disposed radially on the furnace hearth, discharging mechanism for unloading the billets in a radial line from the furnace hearth, selector mechanism for integrating the hearth movemen-ts into predetermined station stops for the charging and discharging mechanisms whereby the billets may be loaded on the hearth at different spacing than billets being unloaded from the hearth where such billets are of different sizes, a time clock controlling the rate of discharge of billets from the furnace, said time clock being adjustable to mantain a predetermined. rate of production of billets of varying sizes.

8. In a rotary hearth furnace, a rotatable hearth, a drive mechanism for rotating said hearth including an electric motor, charging mechanism for loading articles to be heated on said hearth, discharging mechanism for unloading the heated articles from said hearth, a selector mechanism operable in response to rotary movement of the hearth for stopping the hearth movement at predetermined distances of hearth |travel to receive a charge or for discharging, the selector mechanism being adjustable to stop the hearth at equal or unequal intervals for charging and discharging, and a time clock 'for controlling the rate of discharge of articles from the furnace in accordance with the varying sizes of such articles, means operable by the discharge meehamsm Ior energizng the hearth drive when the seleetor mechanism is set for equal spacing of the hearth for both the charge and diseharge operations, and means operable by the eharging' mechanism for energizing the hearth drive mechanism When the selector mechansm is adjusted for unequal intervals of hearth movement between the ehargng and discharging' statons.

RANDAL E. TALLEY.

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

UNITED STATES PATENTS Number Name Date 410,108 Kennedy et ai Aug. 28, 1889 428,301 Forter May 20, 1890 Number Number Name Date Linkenauger Apr. 19, 1932 Adams Sep-t. 10, 1935 Dixon Aug. 4, 1936 McLay Mar. 1937 Keener Aug. 18, 1942 Keener et al. Sept. 22, 1942 I-Iamlink Apr. 13, 1943 Sylvester Nov. 1, 1949 FOREIGN PATENTS Country Date Denmark July 1, 1925 OTI-IER REFERENCES Pages 276, 277, 278 and 279 of Trinks Industrial Furnaces, vol. II, second edition, copyright 1942, published by John Wiley and Sons, New York,