US2096567A - Blast furnace charging mechanism - Google Patents

Description

Filed Oct. 15, 1935 4 Sheets-Sheet 1 MER W on m E 3 INVENTOR ATTORNEY Oct. 19, 1937. F. I. SMITH BLAST FURNACE CHARGING MECHANISM Filed Oct. 15, 1935 4 Sheets-Sheet 2 INVENTOR ATTORNEY BY (I 5 FIQZ 203 ZbZ m) m w ml. FL E E 8 M8 mL E TL T AA AR TM T 5 L R R Oct. 19, 1937. sMlTH 2,096,567

BLAST FURNACE CHARGING mzcnmusm Filed Oct. 15.1935 4 Sheets-Sheet 3 TD|3 1 T0 REVOLVING TOP CONTROLLER INVENTOR ATTORNEY Oct. 19, 1937. l. SMITH BLAST FURNACE CHARGING MECHANISM Filed Oct. 15, 1955 4 She ets-Sheet 4 m 7 n M M 3 1%! I. INVENTOR ATTORNEY certain average height.

Patented Oct. 19, 1937- BLAST FURNACE CHARGING MECHANISM Frank 1. Smith, Wilkinsburg, Pa.., minor to i I Otis Elevator Company, New York, N. Y.,- I corporation of New Jersey Application 0ctober 1 5, 1935, Serial No. 45,031 scam (Cl. 214-36) The invention relates to the control of the charging of blast furnaces.

In a typical blast furnace installation, the stock for the furnace is loaded into a skip bucket at a loading point. The skip is then hoisted to the top of the furnace where the stock is dumped onto a small bell. The small bell is then operated to dump the stock onto a-large bell and then reclosed. Another load is then brought up from the loading point and dumped onto the small bell which thereupon dumps the stock onto the large bell and recloses. This cycle of operation is repeated until a certain number of loads have beendumped onto the large bell whereupon, after reclosure of the small bell, the large be dumps the charge into the furnace.

It is desirable to maintain thelevel of the stock in the furnace, that is the stock line, at a vention is to automatically control the height of the stock in the furnace.

It may happen that, as the time arrives for dumping the large bell, the stock line is such, due for example to the furnace not being drawn or the charge becoming stuck, that to dump the large bell would overfill the furnace. This would be highly. objectionable, not only from the standpoint of operation, but it might prevent all the new stock dropping into the furnace and thus prevent the closing of the large bell.

It is a specific object of .the present invention to automatically control the charging of a blast furnace in accordance with the stock line so that the furnace will not be overfilled.

One feature of the invention is to stop operation of the charging mechanism when, as the time arrives to dump the large bell, the stock line of the furnace is above a certain point.

Another feature resides in automatically resuming operation of the charging mechanism when the stock line drops to a certain point.

Other features and advantages of the invention will become apparent from the following description and appended claims.

In the drawings:'-

Figure 1 is a simplified schematic representation of a blast furnace installation embodying the invention;

Figure 2 is a view of stock line recorder mechanism employed in the installation;

Figure 3 is a diagrammatic representation of commutating mechanism associated with the bell operating mechanism;

Figure 4 is a simplified wiring diagram of certain of the power and control circuits of the con- The object of the in- 'trol system for the blast loading pit 20l furnace chargin anism; and i g mach Figure 5 is a diagrammatic representation of a control panel, showing particularly the relationshipof the coils and contacts oi. the various electromagnetic switches employed in the control system of Figure 4.

For a general understanding of the invention reference may be had toFigure 1, wherein va-. rious parts of a blast furnace installation are indicated by reference-characters. The stock for the furnace is carried in a skip bucket 200 from a to a hopper 202 at the top of the furnace. Two

skips are illustrated, these skips running on separate tracks from the loading pit to the hopper. Each of the tracks is arranged at the top to automatically dump the skip as it arrives at the hopper.

The skip buckets are raised and lowered by skip hoisting mechanism. This mechanism comprises roping 205 connected to one of theskips and passing around a drum 200 which is driven by a motor I90, and similar roping connected to the other skip and passing around drum 208. The roping is arranged on the drum so that one skip is raised from the loading pit to the hopper as the other is returned to the pit. One end of the roping for one skip is connected to the skip and extends therefrom upwardly to an idler sheave 208 and thence downwardly around hoisting drum 206. The roping for the other skip is simihoisting motor.

larly arranged but is wound oppositely on. the drum. An electromechanical brake 2 having a release coil I16 is provided for stopping the The hoisting motor and brake are controlled through a master control switch I69 arranged at the loading platform for manual operationby an operator. Mechanically operated switching dumped onto the small bell, the cycle of operation is repeated, dumping the load ontothe large bell. When a specified number of loads have been dumped onto the large bell, the large bell is opened, dumping the charge into the furnace.

When the small bell is opened and dumps a ceiving another load. Also, the large bell is not mechanism. Small bell load, it is returned to closed position before resmall bell has been closed, and the large bell is returned to closed position before the small bell is opened. This seals the furnace, an outlet for the gases at the top of the furnace being provided by pipe 2|6, which carries the hot gases to the heaters and other parts in the installation.

The bells are operated by the bell hoisting opened until the low rod 220 to one end of lever 22I. At its opposite end lever 22! carries a counterweight 223 of sufilcient mass to counterbalance the weight of the bell and the rod plus the weight of the load of material resting on the bell, and to provide sufficient force to maintain a sealing pressure between the bell and its seat. Large hell 2 l 5 is connected to a lever 225 by a rod 224 which extends through hollow rod 220. v with a counterweight 226 which counterbalances the weight of the bell and rod as well as the weight of material resting on the bell and pro vides sufficient sealing pressure between the bell and its seat.

In the hoisting machine for the bells, drums 221 and 228 are loosely mounted upon a shaft 230 supported by bearing pedestals mounted on base 23l. Hoisting cable 232 for small bell, 2l4 hasits lower end secured to drum 221, passes over sta-.

tionary pulleys 233 and 234 and is connected to the weighted'end of lever 22!. Hoisting cable 235 for large bell 215 has its lower end secured to drum 228, passesover stationary pulleys 236 and 231 and is connected to the weighted end of lever 225. Rotation of drum 221 from the neutral position shown causes cable 232 to move the weighted end of lever 22l upwardly, thereby opening small bell 2, and rotation of drum 228 from this neutral position causes cable 235 to move the weighted end of lever 225-upwardly, thereby opening large bell A driving gear 240 is keyed to shaft 230. A lug 241 is provided on each side of the gear. A lug 242 is arranged on drum 221 in the path of movement of the lug on the left sideof gear 240 so as to be engaged thereby when the gear is rotated to move from neutral in a counterclockwise direc tion as viewed from the left hand end of the bell hoisting machine. Continued movement of the gear after the engagement of the lugs causes drum 221 to rotate therewith, thereby opening the small bell. To close the small bell, the direction of rotation of gear. 240 is reversed to allow drum 221 to return to neutral under the influence of weight 223. A similar lug 243 is arranged on drum 228 in the path of movement of the other lug 24l so as to be engaged thereby when gear 246 is rotated from neutral in the opposite direction. Continued rotative movement of the gear after lug 243 is engaged causes rotation of drum 228 to open large bell 2 l5. In closing hell 2 l 5, the direction of rotation of gear 246 is reversed to allow drum 228 to return to neutral under the influence of weight 226.

Driving gear 240 is driven through a train of gears 245 by motor I50 mounted on base 23!. An electromechanical brake 246 having a release coil I43 is provided for bringing the rotating members rapidly to rest when the motor is deenergized: The operation of the motor and brake is controlled by switching mechanism 250 actuated in accordance with the positions of the bells, by certain of the switches actuated in accordance with the positions of the skips and by switching 2 is connectedby hol- Lever 225 is likewise providedmechanisi'n actuated by the'stock line recorder mechanism, these various switching mechanisms acting .through the intermediary of electromagnet-1c switches. Switching mechanism 250 is illustrated as driven from shaft '23fl. 7

Commutating mechanism H0 is also driven from shaft 230, this mechanism acting'to control the operation of the bell indicator 252 and to control the sequence of operation of the bells. The bell indicator comprises a column of lamps J09 arranged at the loading platform for observation by the operator to indicate which of the bells. is in operation and, in the case of the small bell, the number of times it has been operated since the opening of the large bell.

Referring to Figure 3, commutating mechanism H0 comprises a series of stationary contacts H2 and H4-l22 inclusive arranged in the arc of -a circle and a contact segment I I3 for engaging and bridging these stationary contacts. This segment is arrangedon a shaft 255 for rotation therewith. The segment is biased into position against a stop 256 with segment H3 in engagement with stationary contact I I2 by a weight 251. This weight is connected to a pulley 258 on shaft 255. The segment is moved clockwise against the force of its biasing weight by means of a ratchet 260 and to shaft 255 while the ratchet is connected by a rod 262 to a'. link 263. This link in turn is actuated by a crank motion from shaft 230 as diagrammatically illustrated. With shaft 230 in neutral position, the crank arm extends horizontally from the center of the shaft.

Upon clockwise rotation of the shaft to open the small bell, the motion imparted to link 263 lifts rod 262. This causes the ratchet to engage the ratchet wheel and move the wheel an amount sufficient to rotate segment H3 into engagement.

with the next stationary contact. From the position in which the segment is shown, the first step of movement causes segment H3 to engage stationary contact H4 and to disengage stationary contact H2. As the small bell is returned to closed position, pawl 264 cooperates with the.

. operation of the large bell. Upon counterclockwise rotation of shaft 230 from neutral to open the large bell, the ratchet is moved away from the ratchet wheel by the crank action and a collar 265 on rod 262 engages and releases pawl 264, permitting weight 251 to return the segment to the position shown against stop 256. This resets the commutating mechanism for another cycle of operation. The ratchet 260 does not engage the ratchet wheel upon return of shaft 230 to neutral to close the large bell. After the closing of the large bell, the small bell is again operated, starting another cycle of operation;

The stock line recorder comprises a rod 210 extending downwardly into the furnace at the top thereof. At the bottom end this rod isprovided with a plate 21! for resting on the stock. The stock line recorder mechanism acts to permit the rod to follow the stock, the upper end of the rod being suspended by a rope 212 which passes over idler pulley 213, downwardly over idler ratchet wheel 26l. The ratchet wheel is secured I pulley 214, around a tensioning sheave 215, and thence upwardly and around a drum 216. The drum 218 is driven by the motor 61 which is provided with an electromechanical brake 218 having a release coil 64.- Commutating mechanism 58 is driven by motor 61 in accordance with the movement of rod 210. This mechanism controls a stock line indicator 218. This indlcator.comprises a series of lamps 62 arranged in a vertical column at the loading platform for observation by the operator.

Reference may be had to Figure 2, which illustrates a stock line recorder machine. Idler pulley 214 is rotatably mounted 'on an arm 280 supported on a pedestal 28l on base 282. Tensioning sheave 215 is rotatably mounted on a shaft 283 carried by an elongated frame 284. This tensioning frame 284 is guided for vertical movement within another frame 285. Frame 284- is biased for downward movement by its own weighu and the weight of sheave 215. For a portion of this downward movement this force is augmented by that of a spring 286 arranged between a plate 292 and a spring seat 281 secured by oppositely disposed studs 288 to frame 285. Additional oppositely disposed studs 290 depend from frame 285 and each is provided at its lower end with a nut 29I for cooperating with plate 292 to form a stop forlimiting the expansion of the spring. A nut 293 on each of studs 288 serves to adjust the compression of the spring.

Frame 284 carries cams 294. and 295. Cam 294 is for operating limit switch 21 while cam 295 is for operating limit switch 22, these limit switches being mounted on frame 285. ,Theseswitches act through electromagnetic switching mechanism to control the operation of motor 61 and brake 218.

Frame 285 is provided with arms 296 having bearing lugs 291 formed on the ends thereof. A pivot shaft 300 extends through apertures provided in these lugs from the base to the top of pedestal 28L This arrangement permits the bracket to swing as rope 212 is wound on drum 216 or unwound therefrom.

Motor 61 for driving drum 216 is vertically mounted. On the lower end of its shaft the motor is provided with a worm 30! which acts through worm wheel 302 to drive the drum shaft 303. The drum shaft acts through a train of gears 304 to drive all-operating shaft 305 for commutating mechanism 58. This commutating mechanism comprises a plurality of stationary contacts 36-54 inclusive arranged in a circle. The first of these contacts 36 is somewhat elongated. A contact ring isarranged in a circle concentric with that of the stationary contacts and a bridge 60, comprising a pair of electrically connected brushes, acts to bridge the contact ring with individual stationary contacts. This bridge is arranged on an arm 306 mounted on shaft 305 for rotation thereby. On the other end of arm 306 is a stop 301 which cooperates with a staticnary' lug 308 to bring the bridge to rest upon clockwise rotative movement with the brushes bridging the contact ring and stationary contact 36.

In operation, assume that the rod 210 has been lifted against a stop 3I0. With the rod in this position, frame 284 is held against the force of spring 286 in position where cam 294 opens switch 21. Upon energization of motor 61 to pay out rope 212, the tensioning frame is lowered before movement of rod 210 takes place. cause the weight of sheave 215 and frame 284 plus the force exerted by spring 286 is more than twice the weight of rod 210. As the tensioning switch 22.

is beframe moves downwardly, spring 286 expands and a position is reached where plate292 engages nuts 28l on studs 280, thereby relieving rod 210 from the effect of the force of'spring 286. The weight of frame 284 and sheave 215 is less than twice the weight of rod 210 so that as the rope continues to be paid out the rod is lowered into the furnace. When plate -21I. engages the top of the stock in the furnace, the rod comes to a stop and further paying out .of rope 212 permits the tensioning frame 284 to continue its downward movement until cam 295 engages and opens This causes motor' 61 to be deenergized and the brake applied to bring the mechanism to a stop.

This mechanism permits the rod to continue to follow the stock, preferably at intervals as will be explained later. When the time arrives to open the large bell, motor 61 is energized to .take up on rope 2.12. This results first in raising the tensioning frame'until a point is reached where the top of the frame engages plate 292 where the force of spring 286 is added to the weight of the tensioning frame and sheave. This increases the downward force exerted on rope 212 at sheave 215 sufficiently to cause rod 210 to be lifted until it is brought to rest by engagement with stop 3I0. Thereaftenthe tensioning frame is raised against the force of spring 286 until cam 294 opens switch 21, which effects the deenergization. of motor 81 and the application of the brake to bring the mechanism to a stop.

The invention is applicable to installations provided with a revolving top. A revolving top has been illustrated in Figure 1. It comprises a hopper 3l5 for the small bell, arranged for rotation in steps by a motor 3I6 through gearing 311. A swivel connection 3|8 between hollow rod 220 and lever 22l is provided to permit rotative movement of the small bell. The purpose of the revolving top is to effect a certain disposition of the various materials of the stock within the furnace. Y

When the stock in the furnace is within a certain distance of the large bell, the furnace is considered full. This distance varies from six to eight feet in present day installations, depend- ,ing upon the area of the furnace at the stock line. The invention involves controlling the operation of the charging mechanism so that no new stock is admitted to the furnace-when the furnace is full as'the time arrives for dumping the large bell. As soon as the stock in the furnace settles to a point where the furnace is no longer considered full, the large bell is dumped and the operation of the charging mechanism is resumed.

In carrying out the invention, the stock line recorder is utilized to control the operation of the large bell. If, as the time arrives to open the large bell, the line of the stock in the furnace is such that the rod is at or above a certain point in the furnace, the operation of the large bell is prevented. In the preferred arrangement, another load may be dumped upon the small bell but, unless in the meantime the rod has been permitted to drop below this point, further operation of the bells, the skip hoist and also of the revolving top, if provided, is prevented. When the stock line in the furnace falls below the predetermined point, the stock line recorder mechanism acts automatically to raise rod 210 up against the stop and to cause the opening of the large bell. Upon reclosing of'the large bell, the

small bell is dumped and the charging mecha bodying the invention, The control and power' circuits of the various units are illustrated as combined in a single wiring diagram Not all of the circuits are shown, the circuits being simplified for convenience of description. However, enough of the circuits for the various units are shown to attain an understanding of the principles of the invention.

No attempt is made in Figure 4 to show the coils and contacts of the various electromagnetic switches and devices in their associated positions, a straight wiring diagram being employed. The separation of the coils and contacts ,of the switches enables the circuits to be arranged in an across the line form, rendering them comparatively simple.

The numerals employed in designating the various elements of the wiring diagram are arranged in sequence, the lowest number, in this case II, appearing in the upper left hand corner and the succeeding numbers following in numerical sequence from left to right downwardly. on the sheet of drawings. The arrangement of numerals in this sequence facilitates location of any element referred to in the description.

The electromagnetic switches have been designatedas follows:

AS-Auxiliary sequence switch BA-Bell accelerating switch BS-Bell sequence switch CL-Charge limiting switch HBHoist bell interlock switch gg} noist direction switches HS-Hoist speed switch LBLarge bell switch OSLarge bell operating switch RAR0d accelerating switch RI-Ie-Rod hoisting switch RI-IRRod hoisting relay R1r-R0d lowering switch SB-Small bell switch TRTime relay Throughout the description which follows, these letters, in addition to reference numerals, will be applied to parts of the above designated switches. For example, contacts RLI2 indicate that these contacts are on the rod lowering switch, while operatingc'oil RHRI03 indicates that the coil operates the rod hoisting relay. The relationship of the coils andcontacts of the above switches may be seen from Figure 5, where the switches arearranged in alphabetical order. It is to be understood that the exact arrangement of the switches is determined by the requirements of the particular installation.

The switches of the switching mechanisms of the various units will be termed limit switches. In accordance with the type of wiring diagram employed, the individual limit switches of each unit are shown separated. In order to difierentiate between the limitswitches of the various units, those operated by the skip hoist mechanism are designated generallyby the letter S, those operated by the bell operating mechanism are designated generally by the letter B and those operated by the stock line recorder mechanism are designated generally by the letter R.

Commutating mechanism III], in addition to cuits to a series of jacks I24 to I32 inclusive.

controlling the bell indicator, controls the cir- A plug I31 is provided for insertion in any one of the jacks to control the number of small bell operations. The jacks are arranged on the control panel shown in Figure 5.

The blast furnace control units are illustrated as arranged for direct current power supply. The power supply lines are designated LI and L2. I I and I6 are blades of a double pole knife switch for connecting the system to the power supply. It will be ass closed.

The motor GTof the stock line recorder mechanism has its armature designated 13, series field winding 69 and its separately excited field winding 65. A series resistance 10 and by-pass resistance 14 are illustrated for controlling the current flowing in armature 13 of the motor. motor I of the bell operating mechanism has its armature designated I55, series field winding I46 and-its shunt field winding I40. A series resistance I41 and by-pass resistance I49 are illustrated for controlling the current flowing in armature I of the motor. The motor I90 of the skip hoist mechanism has its armature designated I83, series field winding I80 and its separately excited'field winding I89. A series resistance I8I and by-pass I81 are illustrated for controlling the current fiowing in armature I83 of the motor.

Master control switch I69 comprises a bridging contact segment I63 operated in one direction to bridge contacts I51 and in the other direction to bridge contacts I68. Contacts I51 control the circuit for coil HUI58 of one hoist direction switch while contacts I68 control the circuit for coil HDI10 of the other hoist direction switch. These coils are also subject to limit switches.

The skip limit switches may be regarded as arranged in sets, each of those functioning for one of the skips, which will be termed skip a, having the letter a appended to its designation and each of those functioning for the other skip, which will be'termed skip 1), having the letter b appended to its designation. The limit switches of set a are S3211, SI59a and SIIiGa, while those of set b are SBIb, SI1Ib and S I14b. Additional limit switches SI92 and SIQIb may be provided for controlling the revolving top which will be referred to later. The bell limit switches are designated B84, B85, B92, B94, B98 and BI01, while those of the stock line recorder mechanism are designated R22 and R21.

It will be assumed that skip b is in the pit below the loading platform and that skip a is in dumping position at the top of the furnace. Under such conditions limit switches S8 lb, SI1Ib and Sl14b are closed and limit switches 882a, SI59a and SI66a are open. Switch SI59a being open prevents the energization of coil HUI58 of hoist direction switch HU. However, as limit switch SI1lb is closed, the hoisting ofskip "b uri'ied that this switch has been This circuit may be traced from supply line LI,

to bypass contacts R'I'RI64 and HSI6I. It also engages. contacts HDI86 and HDI'I8 to complete a circuit for the armaturel83 of the skip hoist motonwhich is from lin'e LI, through contacts -HDI 86, armature I83, contacts HDII8, series field winding I 80 and-resistance I8I to line L2. Con.- tactsHDII5 are also engaged, completing a circuit for release coil II6 of the skip hoist electromechanical brake.-

'* The brake-being released and the skip hoist motor being energized, its separately excited field win'ding I89 being directly connected across lines LI and L2, the skip operating mechanism starts in a direction to hoist skip b and to return skip a to the loading pit. As the counter E. M. F. of armature I83 builds. up, coil HSI84 of the hoist speed switch is energized sufiiciently to engage its contacts HSI85 and separate its contacts HSI82 and I-ISISI. Contacts HSIGI are in the initial energizing circuit for the coils of the direc-.

tion switches, these contacts serving to prevent the sudden reversal of the direction of rotation of the skip operating motor. These contacts are now by-passed by contacts HDI'I3,.m.aintaining coil HDIIIl energized. Contacts HSI82 discon nect by-pass resistance I8'I from across armature I83, while contacts HSI85 short-circuit resistance I8I and series field winding I80. This brings the skip hoist motor up to full speed.

As skip 1) leaves the pit, limit switch SI59a closes and thereafter limit switch SI'I4b opens. It will be assumed that contacts HBI62 of the hoist bell interlock switch are engaged before the opening of limit switch SII4b takes place. This being the case, the circuit for coil HDIIU is maintained through contacts HJBI62 and HDI'I3.

As skip b nears its dumping position, limit switch SI66a closes and ash; reaches this position limit switch SI'IIb opens. The opening of 'limit switch SI'IIb breaks the circuit for coil HDI'IO which separates its contacts HDIBG and HDI I8 to disconnect the skip hoist motor from the supply lines and also separates its contacts HDI'I5 to deenergize brake release coil "6 of the skip hoist electromechanical. brake. Thebrake is applied to bring the skip hoisting mechanism to a stopwith skip b in its dumping position and skip "(1 in its loading position, being assisted by the by-pass resistance I81 reconnected across the motor armature by the dropping out of hoist speed switch HS to engage contacts HSI82. It will be understood that the control system may be arranged to cause the by-pass resistance to. be con-' nected across the armature'before the final stopping operation and that resistance I 8| may be controlled in several steps to control acceleration HUI'I'I and HUI.88 to establish a circuit for the skip hoist motor for rotation in the opposite -direction. At the same time it engages contacts HUI6'I to energize brake release coil I'IB. Thus skip a is started in the up direction and skip b is started on its return to the loading station.

As skip a reaches its dumping position, it is dumped. 1 ."Skip' b is started virrthe updirection by m'ovement of control switch jsegment I63 in a position to bridge contacts I68, as previously described. No further description'of raising and lowering the'skips is necessary ,asitfis Simply a .repetitio'nof that alreadyjdescribed; 5''

Both bells are closed while a skip is being dumped With the bells closed, bell limit switches B84, B85'and B94 are open and bell limit switches B92, B98 and BIO'I are closed. Skip limit -switch--S82a is opened as skip a arrives within about ten' feet of its dumping position. Similarly limit switch S8Ib is opened as skip b arrives within about ten feet of its dumping position. Thus either limit switch S8Ib or limit switch S8211 is open when the skip is being dumped.

Assume that skip a is being dumped. As the skip is returned to the loading pit and reaches a point say ten feet away from the dumping position, limit switch S82a closes. Thus, as limit switch S8Ib is already closed, this completes a circuit for operating coil SE90 of the small bell switch. This circuit is from line LI through skip limit switches S8Ib and S82a, contacts H386 of the hoist bell interlock'switch and contacts AS8I of the auxiliary sequence switch, coil SE90, interlock contacts LB9I of the large bell switch, bell limit switch B92 and contactsTR93 of the time relay to line L2, operating coil TRI38 of the time relay being energized at this time, through contacts SBI35 of the small bell switch and contacts LBI36 of the large bell switch Small bell switch SB, upon operation, separates contacts SB!" and SBI35 and engages contacts SBI4I, SBI44 and SBI56. Contacts SE91 are interlock contacts in the circuit for coil LB96 of the large bell switch. Contacts SBI35 break the circuit for coil TRI38 of the time relay which separates its contacts TR93, the circuit for coil SE90 being thereafter maintained through resistance I04. Contacts SBI44 and SBI5B complete a circuit for armature I55 of the bell operating motor through resistance I41. Contacts SBI4I complete a circuit'for release coil'l43 of the bell operating mechanism electromechanical brake.

The brake being released and the bell operating motor being energized, its separately excited field winding I40 being connected directly across lines LI and L2, the bell operating mechanism starts in operation, the direction of'rotation of the motor being such asto' permit the opening of the small bell. its operating coil'BAI52 connected across armature I55. This switch operates upon the counter E. M. F. of the motor reaching a certain value to separate contacts BAI48 and engage contacts BAI53. The separation of contacts BA I48 disconnects by-pass resistance I49 from across armature I55 while the engagement of contacts BAI 53 short-circuits series resistance I41 and series field winding I46. This brings the bell operating motorup to full speed.

As the bell operating mechanism starts in op-' eration in a direction for lowering the small bell, its limit switches B85 and B94 close. Limit switch B85 establishes a circuit by-passing skip limit switches S8Ib and 882a and contacts HB86 and ASB'I in the circuit for coil SE90. The purpose of limit switch B94 will be explained later. After the closing of limit switch B85, limit switch B84 closes, which completes a circuit for op- Bell accelerating .switch BA has a brought to astop by the opening tr, limit switch -SI59d. Skip b, which has been returned to its loading position, is loaded as" skip.a is being crating coil H883 of the hoist bell interlock switch through skip limit switches S8") and 3920. This switch, I upon operation, separates contacts H389 and engages contacts H890 and HBIH.

Contacts H300 establish a self-holding circuit bellswitch, this switch being maintained energized, however, through bell limit switch B85.

As'the small bell is lowered it dumps the stock thereon onto the large bell. As it reaches its full lowered position, belllimit switch B92 opens, breaking the circuit for coil SE90 oi the small bell switch. The small bell switch, upon dropping out, reengages contacts SB9I andSBI35 and separates contacts SBI4I, SBI44 and SBI56. .The separation of contacts SBI4I deenergizes brake release coil I43 while the separation of contacts SBI4'4 and SBISG disconnects bell operating motor armature I and series field winding I46 from lines LI and L2. The hoisting motor being deenergized and the brake: being applied, the bell operating mechanism is brought to a stop, the brake being aided by by-pass resistance I49 which is reconnected across motor armature I55 by the reengagement of contacts BAI48 as the armature voltage drops to a certain value. It is to be understood that the control system may be arranged to cause the by-pass to be reconnected across the motor armature before the final stopping operation and that resistance I41 and series field winding I46 may be controlled in steps to control acceleration and retardation of the bell operating motor.

The reengagement .of contacts SE91 completes a circuit for operating coil LB96 of the large bell switch from line LI through bell limit switch B94 and the coil L396, contacts SB9I, bell limit switch B98 and resistance I04 to line L2. Owing to resistance I04, the voltage applied to boil LB96 is insufficient to cause the large bell switch to operate. However, the reengagement of contacts SBI35 completes a circuit iior coil TRI38 of the time relay which, upon expiration of its time interval, engages contacts TR93 to short-circuit resistance I04. Upon the shortcircuiting of resistance I04, suflicient voltage is applied to coil LB96 to operate. the large bell switch for returning the small bell to closed position. Thus the small bell is maintained open for a suflicient time to insure that all the stock thereon is dumped.

The large bell switch, upon operation, separates contacts LB9I. and LBI36 and engages contacts LBI42, LBI45 and LBI54. Contacts LB9I serve as an electrical interlock for coil SE of the small bell switch. Contacts LBI36 break the circuit for coil 'I'RI38 of the time relay. Contacts LBI45 and LBI54 establish a circuit for armature I55 of the bell operating motor for reverse rotative movement. The engagement of contacts LBI42 completes a circuit for brake release coil I43. Thus the bell operating mechanism electromechanical brake being released and its motor being energized, the bell operating mechanism operates in the reverse direction permitting the biasing weight for the small bell to return the smallbell to closed position.

As the small bell reaches closed position, bell limit switch B94 opens, breaking the circuit for coil L396 of the large bell switch. The large bell switch, upon dropping out, reengages contacts LBOI and LBI" and separatescontacts LBI42,

LBI45 and LBI54. Contacts LB9I prepare a circuit for another operation of small bell switch SB 'andco-ntacts LBI30 reestablish a circuit for coil 'I'Rlfl'ot the time relay. Contacts LBI54 and LBI45 break the circuit for the bell operating motor. Contacts LB I42 break the circuit for brake release coil I43. Thus, the bell operating motor being deenergized and the brake being applied, the bell operating mechanism is brought to a stop.

The above described operation of the bell operating mechanism is repeated for the next load dumped onto the small bell by a skip. Under the assumed conditions of operation, skip "b" is the next to dump its load. Thus, skip limit switch S8: is opened as the skip nears its dumping position. The opening of this switch breaks the circuit for coil H383 of the hoist bell interlock switch which drops out to reengage its contacts H1396 and to separate contacts H890 and HBI62. The reengagement of contacts H386 further prepares the circuit .for reenergization of coil S390 of the small bell switch. Upon operation of the skip operating mechanism to return skip b to the skip loading position and after say ten feet of downward movement of the skip, skip limit switch- S8Ib closes completing the circuit for coil SE90 of the small bell switch. Thus the cycle of operation of opening the small bell to dump the stock onto the large bell and returning the small bell to closed position as above described is repeated.

These operations are repeated until a predeterthe small bell onto the large bell. The number of loads is selected by inserting plug I31 in a corresponding one of the jacks. Assume that it is desired to have five loads dumped onto the large bell before the above cycle of operations isinterrupted. For this operation, plug I31 is inserted in the fifth jack I28.

As previously explained, each successive operation of the small bell causes an operation of the bell commutating mechanism III). Upon the dumping of the first load onto the large bell, segment II3 of the commutator device moves off stationary contact H2 and into engagement with stationary contact II4. This causes lamp I09 connected to contact II2 to go out and the lamp connected to contact II4 to be illuminated. This indicates that the mechanism is on the first small bell operation. Upon the second small'bell operation, segment II3 moves into engagement with contact H5, lighting lamp I09 connected to that contact. In this way the successive lamps are lighted indicating the number of operations of the small bell.

Upon the fifth operation, segment II3 moves into engagement with stationary contact II8, not only lighting the lamp connected thereto but also completing a circuit through jack I28 and plug I31 for coil BSI34 of the bell sequence switch. This switch, upon operation, engages contacts BS'I08. completing a circuit for coil ASIDE of the auxiliary sequence switch. Switch AS operates to separate contacts A881 and to engage contacts ASI00 and ASI05. 'Contacts ASI05 establish a self-holding circuitf Contacts AS8l are interlock contacts and serve to prevent the energization of coil SE90 of the small bell switchduring this portion of the cycle of operation. Assuming charge limiting switch CL to be deenergized, the engagement of contacts ASI00 completes a circuit for coil RHRI03 of the rod hoisting rela through contacts CLIOI. I

The rod hoisting relay, as will be explained later, causes the rod of the stock line recorder to be raised from the stock line in the furnace until it is brought to a stop by abutment 3!!! (see Figure l), as previously described. As the rod is lifted, bridging contact 60 of the stock line recorder commutating device 58 is moved back into position where'it bridges contact 36 with segment 35. This completes a circuit for coil OSBI of the large bell operating switch. This switch separates contacts OS'H and engages contacts Si02. The purpose of contacts OSII will be explained later. Contacts 0Sl02 complete a circuit through contacts ASIODand CLIOI by-passing bell limit switch B94 in the circuit for coil L336 0! the large bell switch. Inasmuch as switch BS is energized during the opening of the small bell, this by-pass circuit is established at the .time the small bell is reclosed and switch B34 opens. Thus the large bell switch is maintained operated. This maintains the brake released and the motor energized, continuing the rotation of the bell operating mechanism past neutral position and effecting the opening or the large bell to dump the stock accumulated thereon into the furnace.

As the large bell starts to open, limit switches B85 and B94 close and as the bell reaches iull open position, limit switches B98 and Bill! open. The opening of switch Bill-i breaks the circuit for coil AS I 06 of the auxiliary sequence switch, which drops out to reengage contacts A881 and to separate contacts ASIUO and ASIOS. The reeng'agement of contacts LBS! of the large bell switch completes a' circuit for coil $390 of the small bell switch through bell limit switches B35 and B32 and resistance I04. The reengagement 01 contacts LBI36 reestablishes a circuit for coil TRI38 of the time relay which, upon expiration of it time interval. engages contacts TR33 to short-circuit resistance I04, causing the small bell switch to operate. This switch effects the release of the brake and establishes circuits for the bell operating motor to eflect the return of the large bell to closed position. As the large bell reaches closed position, bell limit switch B35 opens, deenergizing the small bell switch. This causes the bell operating mechanism to be brought to a stop.

During the-operation of the large bell, segment H3 of the bell commutating device is returned to the starting position where it engages contact I I2 to reestablish a circuit for the lamp I03 connected to this contact. This indicates that a large bell operation is being performedand the next operation will be an operation of the small bell. This cycle of operation as above described is repeated upon the dumping of another skip load onto the small bell and the return of the skip toward the loading pit, the large bell being dumped again after the selected number of loads have been dumped thereon from the small bell.

Coil RHRIII3 of the rod hoisting relay is maintained energized after the separation of contacts ASIUD, as a result of the opening of bell limit switch Biol as the large bell reaches fully open condition, through bell limit switch B94 and contacts OSI02. Thus this relay is maintained energized until switch B34 opens as the large bell reaches closed position. When this occurs, relay RHR drops out to .reengage contacts RHRII and RHR32 and to separate contacts RHRM. 'Contacts RHRN are in the circuit for coil EH25 of the rod hoisting switch, preventing the establishment of a circuit for this coil, while contacts RHRII are in the circuit for coil RLIB oi' the rod lowering switch. Operating coil RLIB or the rod lowering switch is further controlled by means of a timing device, designated generally by referonce letters TD. A timing device suitable for this purpose is illustrated in Figure 5.

Referring to Figure 5, this timing device comprises a motor 3 whichv operates through reduction gearing "2 to drive a shaft 3l3.

An idler gear 3 is supported by one arm of a bell crank lever 320 freely mounted on shaft 3. The idler gear is driven by the reduction gearing and is adapted to be thrown into mesh with another gear 32i by lever'320. The other arm or lever 320 constitutes the armature of a clutch magnet, the coil of which is designated I3. 'When this magnet is energized, lever,320 is swung counterclockwise to mesh idler gear 3 with gear 32l. When motor 3 is in operation and the ciutch magnet is energized, meshing gear 3 with gear 32l, gear 32l is rotated in a clockwise direction. Upon the engagement of a pin 322 on gear 32| with arm 323 01' bell crank lever 324, lever 324 is swung gradually counterclockwise about its pivot. This lever is connected by a spring 325 to a contact lever 323. When'the lower end of the spring is moved beyond the center line through the pivot for contact lever 328, the contact lever is thrown clockwise about its pivot with a snap action. This disengages a contact carried by the lever from a cooperating stationary contact and moves another contact carried bythe lever into engagement with another stationary contact. These cooperating contacts are designated l5 and 23. Upon the separation of contacts l5 the timing motor is deenergizedas will be shown later. Ii! the clutch magnet is maintained energized the contacts will be retained in this position with contacts I! separated and contacts 23 in engagement. Upon deenergization of the clutch magnet, lever 320 drops, disengaging idler gear 3 from gear 32l and a torsion spring 321 associated with gear 32| returns the gear in a counterclockwise direction to the position from which it started. As this movement takes place, pin 322 moves away from lever 324, which is swung back about its pivot by a spring 330. As spring 32! passes the center line through the pivot for contact lever 326, the contact lever is snapped back into the position illustrated, separating contacts 23 and reengaging contacts l5. As gear 32! arrives at its former position, it is brought to rest by the engagement of a pin 33l carried thereby with a stop 332. The time interval provided by the timing device is from the time the motor and clutch are energized until the engagement oil contacts 23 takes place. This time interval may val for which the timing device is set expires before the large bell is closed, contacts TD23,

upon engagement, are maintained so for the separation of contacts TDIB, although breaking the circuit for armature TD and field winding TD20 of the timing device motor. does not deenergize clutch magnet coil TDI3. Under such conditions, the engagement of contacts RHRII completes the circuit for coil RLI3 of the rod lowering switch. Otherwise, this circuit is completed upon the engagement of contacts TD23 of the timing device as the time interval expires. This circuit is through contacts RHRIT, coil RLI8, contacts RHZI, stock line recorder limit switch R22 and contacts TD23.

Switch RL, upon operation, separates contacts RLI2 and RL26 and engages contacts RL30, RL59, RL66 and RLI8. Contacts RL26 are arranged in the circuit for coil RH of the rod hoisting switch. These contacts serve as an electrical interlock. Contacts RL30 by-pass-contacts TD23 of the timing device, thereby establlshing a self-holding circuit. Contacts RLI2 break the circuit for the timing device motor armature TDM and field winding 'I'D20 and for clutch magnet coil 'I'Di3. This causes the separation of contacts TD23 and the reengagement of contacts TDl5. Contacts RL66 and RL'I8 complete a circuit for armature 13 and series field winding 69 of the stock line recorder motor through resistance 10. The engagement of contacts RL59 completes a circuit for brake release coil 64 of the stock line recorder mechanism. The separately excited field winding 65 of the recorder motor is connected across lines LI and L2. Thus, upon the brake being released, the stock line recorder mechanism starts in operation, the direction of rotation of the motor beingsuch as to lower the rod into the furnace. The initial operation of the stock line recorder effects the reengagement of limit switch R21. When plate 292 engages nuts 29! (Figure 2), the rod starts to lower into the furnace.

The lowering of the rod takes place at a slow speed owing to the fact that contacts RL66 prevent the energization of coil RAH of the rod accelerating switch and contacts RAIS remain separated. Thus, series field Winding 69 and resistance" remain connected in series with the motor armature I3 and the by-pass resistance 14 remains connected across the motor armature.

When the rod has been lowered into position where the plate on the lower end thereof strikes the stock in the furnace, the recorder mechanism acts as previously described to open limit switch R22. This breaks the circuit .for coil RLI8 'of the rod lowering switch. Switch RL drops out to reengage contacts RLI2 and RL26 to separate contacts RL30, RL59, RL66 and RLI8. Contacts RL26 are in the circuit for coil EH25 of the rod hoisting switch, the circuit for this coil being open at contacts RHR24. The separation of contacts RL66 and RLI8 breaks the circuit for the operating motor of the recorder mechanism andas contacts RL59 break the circuit for the brake release coil 64, the stock line recorder mechanism is brought to a stop with the rod in its lowered position.

During the lowering of the rod, bridging contact 60 of commutator device 58 moves into position successively bridging the stationary contacts with feed contact 35. Upon the disengagement of contact 60 from stationary contact 36, the circuit for coil OS6I of the large bell operating switch is broken. This switch thereupon drops out to separate contacts OS|02 in the circuit for causing operation of large bell switch LB to effect the opening of the large bell and reengages contacts OS" in the circuit for coil RA'I2 of the rod ac-- celerating switch. Upon the/engagement of contact 60 with stationary contact 31 a circuit is completed through contacts RHR32 of the rod hoisting relay for operating coil CL33 of the charge limiting switch. Switch CL, upon operation, separates contacts CLIOI in the circuit for coils LB96 and RHRID3 and engages contacts CL3I to establish a self-holding circuit. Upon the engagement of contact 60 with contact 38, a circuit is completed for the first of the series of lamps 62 of the stock line indicator.

The reengagement of contacts RLIZ reestablishes the circuit for the timing device which starts in operation. Upon the expiration of the time interval for which this device is set, say one minute, it reen'gages contacts TD23 to reestablish the circuit for coil RLI8 of the rod lowering switch. This switch operates as before to permit the plate on the lower end of the rod to drop to the point to which the charge in the furnace has settled. The above cycle of operation is repeated at the specified time intervals.

Assume that before bell sequence switch BS is operated bridging contact 60 is moved into engagement with contact 43. This establishes a short-circuit forv coil CL33 of the charge limiting switch, causing the charge limiting switch to drop out to reengage contacts CLI 0 I. Thus, upon the operation of auxiliary sequence switch AS to engage contacts AS160, as a result of the operation of bell sequence switch BS to engage contacts BSIOB, a circuit is established for coil RHRI03 of the rod hoisting relay. This relay operates as previously described to separate contacts RHRH and RHR32 and to engage contacts RHR24. Contacts RHR24 establish a circuit for coil EH25 of the rod hoisting switch through contacts RL26 and limit switch R21. Contacts RHRI'I prevent the energization of coil RLI8 of the rod lowering switch. The rod hoisting switch, upon operation, separates contacts RH2I and engages contacts RH63, RH68 and RH'I6. Contacts RHZI are in the circuit for coil RLI8 and serve as an electrical interlock. Contacts RHBB and RH'I6 complete a circuit for armature I3 and series field winding 69 of the stock line recorder operating motor through series resistance 10 in a direction for operating the motor to lift the rod, the brake being released as a result of the engagement of contacts RH63 to establish a circuit for brake release coil 64. Inasmuch as the circuit for coil RHRI03 is established during the opening of the small bell, the hoisting of the rod startsduring this portion of the cycle of operation. In addition, coil RA'I2 of the rod accelerating switch is energized during the hoisting of the rod. This causes contacts RAT! to be separated, disconnecting by-pass resistance 14 from across armature I3 and contacts RA'I5 to be engaged, shortcircuiting resistance 10 and series field winding 69. Thus the rod is lifted at full speed so as not to delay the opening of the large bell upon return of the small bell to closed position.

The bridging contact 60 is returned to its former position as the rod is raised in the furnace. Upon the engagement of this contact with stationary contacts 31, a circuit is not completed for coil CL33, owing to the fact that contacts RHR32 are separated. The engagement of bridging contact 60 with contact 36, however, establishes a circuit for coil OS6I of the large bell operating switch which operates, as previously described, to engage contacts 0SI02 in a circuit for causing the opening of the large bell and to separate contacts OS". The separation of contacts OS'H breaks the circuit for coil RA'I2 of the rod accelerating switch which separates contacts RA'IS and engages contacts RA". The separation of contacts RAIS reinserts resistance 10 and series field winding 69 in series with motor armature thereafter brought to a stop by stop IIO and thereafter the motor is brought to a stop by the opening of limit switch R21 to deenergize .coil EH of the rod hoisting relay.-

So long as the stock in the furnace has settled to or below a point causing the dropping out of charge limiting switch CL as the time arrives for opening the large bell, the above described cycle of operation will be continued. However, if the stock line is above such pointat this time, the

mechanism operates automatically to prevent the opening of the large bell until the stock has settled to or below this point.

Assume that at the time that bell sequence switch BS is energized in preparation for effecting the opening of the large bell, the stock line in the furnace is at such a height as to prevent bridging contact 60 of commutating device 58 engaging contact 43 to drop out charge limiting switch CL. Under such conditions, the operation of auxiliary sequence switch AS to engage contacts' ASIilildoes not establish a circuit for coil RHRl03'of the rod hoisting relay, owing to the fact that contacts CLIM are separated. Thus, the hoisting of the rod of the stock line recorder does not take place. However, the operation of the bell operating mechanism to effect the dumping of the stock from the small bell separated. Thus, not only is the opening of the large bell prevented when the furnace is full but also further operation of the small bell is prevented aiter it completes the dumping of the last load of stock onto the large bell.

Since further operation of the bell operatin mechanism is prevented when the furnace is full as the time arrives to dump the large bell, bell limit switch B84 is not closed and coil HBO! of the hoist bell interlock switch is not energized. Thus, contacts HBIBI remain separated, which brings the skip operating mechanism to a stop. For an understanding of this operation, assume that skip a is the one which dumped the last load onto the small bell. Thus, uponthe re, closure of skip limit switch 882a as skip 0'' starts down the incline, a circuit is not established for coil H1383 owing to hell limit switch B84 being open. Contacts H'BIB? therefore remain separated so that the opening of skip limit switch Sl'Hb, which occurs after the closing of limit switch 582a, breaks the circuit for coil HDIIO of hoist direction switch HD (switch HID being the hoist direction switch which was op-' erated under the assumed conditions). This causes the skip operating mechanismv to be brought to a stop with the skips in the positions to which they have-been moved. Thus the entire charging operation is suspended. The stock line recorder, however, continues to function, permitting the lowering of the rod at successive intervals to follow the stock in the furnace.

When the stock in the furnace settles to a point permitting the operation of commutating device 58 to effect the bridging of contact 4 3 and contact 8l,- coil CL of the charge limiting switch is short-circuited, causing the reengagement of contacts CLIOI. This causes the operation of the rod hoisting relay RHR to cause the hoisting of the rod. As the rod reaches its uppermost position, switch OS is operated to engage contacts OSIM, establishing a circuit for coil LB" oi the large bell switch. This causes,

the bell operating mechanism to open the large bell, dumping the material thereon into the furnace. As the large bell reaches open position, bell limit switch Bill! opens to deenergize coil ASIOB of the auxiliary sequence switch, which engages contacts 'ASB'I. Thus, a circuit is established by-passing bell limit switch B85, thereby continuing operation of the bell operating mechanism through neutral to open the small bell as the large bell is returned to closed position. As the small bell opens, bell limit switch B closes after reclosure of bell limit switch B85. The closing of switch B84 operates hoist bell interlock switch HEB, which engages contacts HE"! and, the operator maintaining the master control switch in operated condition, this starts the skip hoisting mechanism in operation from the point at which it was brought to a stop. Thus, as soon as the stock line in the furnace falls to a point where the furnace is no longer considered full, the charging mechanism is automatically restarted in operation from the point it left on.

The lamps 82 of the stock'line indicator indicate the height of the stock in the furnace. The first of the lamps shows when the furnace is full while those connected to contacts beyond contact 43 show that the furnace is not full and to what point below the full line the stock has settled.

It has previously been pointed out that the invention is applicable to a blast furnace installation having a revolving top. Circuits for interlocking the revolving top controller with the other control mechanism have been illustrated in Figure '4. The revolving top controller may be of the type shown in the patent to Mortensen, No. 1,790,942, dated February 3, 1931, and the circuits have been illustrated for application to such type of control. Skip limit switches SI9ib and Bilia act to control the operation of the revolving top, these limit switches corresponding to limitswitches i3 and ll of the revolving 'top control system shown in the Mortensen patent. With this arrangement, when the furnace is full as the time arrives for opening the large bell, skip limit switches Slfllb and SI92a prevent further operation of the revolving top controller. Skip limit switch Si92a is closed as skip 11" reaches its dumping position, while skip limit switch Slfllb is closed as skip b reaches its dumping postion. At other times these limit switches are open. Thus, as the skip hoist mechanism is-brought to a stop upon a certain distance of skip travel after a load is dumped on the small bell under conditions where operation of the large bell is prevented because the furnace is full. the operation of the revolving top is also prevented. Contacts RTRIS are contacts on a revolving top relay, the operating coil of which may be connected in parallel with coil lllw of the control system of the Mortensen patent. With this arrangement, contacts R'I'Ri remain separated until the cycle of operation of the revolving top has been completed and the revolving top motor has been brought to a stop. This prevents the starting of the skip hoist during revolving top operation, which in turn prevents operation of the bell operating mechanism.

Thus it is seen that, when the furnace is full as the time arrives to dump the large bell, not only is further operation of the bells prevented and the skip hoist brought to a stop, but. in an installation provided with a revolving top, further operation of the revolving top is prevented. It will also be seen that as soon as the stock line in the furnace drops to a point where the furnace is no longer considered full, the operation of the charging mechanism is automatically resumed.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:-

1. In combination; a blast furnace having a small bell and a large bell at the top thereof, the large bell being arranged below the small bell; mechanism for operating said bells; control means for. causing said bell operating mechanism to operate the small bell a predetermined number of' times to one operation of the large bell; a rod extending downwardly into; the furnace at the top thereof; hoisting mechanism for said rod; means for controlling the operation of said rod hoisting mechanism to cause the bottom of the rod to follow the stock as it sinks in the furnace between operations of the large bell; means operable upon the last of the said predetermined number of operations of the small bell, under conditions where the top of the stock in the furnace beneath the rod is below a certain level, to cause operation of said rod hoisting mechanism to lift the rod, said means being ineffective to cause operation of said rod hoisting mechanism to lift the rod when the top of the stock beneath the rod is above said predetermined level; and means controlled by the lifting of said rod and operable as the rod in being lifted reaches a predetermined height in the furnace to cause operation of said bell operating mechanism to operate the large bell.

2. In combination; a blast furnace having a small bell and a large bell at the top thereof, the large bell being arranged below the small bell to receive stock from the small bell; mechanism for dumping successive loads of stock onto the small bell; mechanism for operating said bells; means for causing said bell operating mechanism to open the small bell to dump stock therefrom onto the large bell and thereupon to close the small bell; means for causing said bell operating mechanism to open the large bell after a predetermined number of operations of the small bell and to reclose the large bell after the stock has been dumped therefrom into the furnace; a rod extending downwardly into the furnace at the top thereof; hoisting mechanism for said rod; means for controlling the operation of said rod hoisting mechanism to cause the bottom of the rod to follow the stock in the furnace during said predetermined number of operations of the small bell, said means being responsive to the last of said predetermined number of operations of the small bell to cause said rod hoisting mechanism to lift the rod; means actuated in accordance with the position of said rod operable, when the top of the stock in the furnace beneath the rod as the time arrives to lift the rod is above a certain point, to prevent operation of said rod hoisting mechanism to lift the rod and to prevent further operation of said bell operating mechaism upon the return of the small bell to closed position after said last of said predetermined number of operations thereof; and means responsive to the stopping of said bell operating mechanism to stop operation of said mechanis for dumping stock onto the small bell.

3. In combination; a blast furnace having a small bell and a large bell at the top thereof, the large bell being arranged below 'the small bell to receive stock from the small bell; mechanism for operating said bells; means for causing said bell operating mechanism to open the small bell to dump stock therefrom onto the large bell and to reclose the small bell; means for causing said bell operating mechanism to open the large bell after a predetermined number of operations of the small bell to dump stock thereon and to reclose the large bell after the stock has been dumped therefrom into the furnace; a rod extending downwardly into the furnaceat the top thereof hoisting mechanism for said rod; means for controlling the operation of said rod hoisting mechanism to cause the rod to follow the stock in the furnace between operations of the large bell, said means being responsive to the last of said predetermined number of operations of the small bell to cause said rod hoisting mechanism to lift the rod; and means actuated in accordance with the position of said rod operable, when the bottom of the rod is at or above a predetermined point in the furnace, to prevent operation of said rod hoisting mechanism to lift the rod and to prevent operation of said bell operating mechanism as the time arrives for operating the large bell to open the large bell and also the small bell upon its return to closed position after said last of said predetermined number of operations of the small bell, said last named means thereafter acting upon the bottom of the rod dropping below said predetermined point to cause said rod hoisting mechanism to operate the large bell and to large bell being arranged below the small-bell to receive stock from the small bell; mechanism for dumping successive loads of stock onto the small bell; mechanism for operating said bells; means for causing said bell operating mechanism to open the small bell after a load has been dumped thereon and to reclose the small bell after the stock has been dumped therefrom onto the large bell; means for causing said bell operating mechanism to open the large bell after a predetermined number of loads have been dumped thereon by the small bell and to reclose the large bell'after the stock accumulated thereon has been dumped into the furnace; a rod extending downwardly into the furnace at the-top thereof; hoisting mechanism for said rod; means for controlling the operation of said rod hoisting mechanism to cause the rod to follow the stock in the furnace and to lift the rod prior to the opening of the large bell; and means actuated in accordance with the position of said rod for controlling the operation of said rod hoisting mechanism, said ball operating mechanism and said mechanism for dumping stock onto the small bell, said last named means acting, when the bottom of the rod is at or above a predetermined point in the furnace as the time arrives for operating the large bell, to prevent operation of said rod hoisting mechanism to lift the rod, to prevent operation of said bell operating mechanism to dump either bell and to stop operation of said mechanism for dumping stock onto the small bell, said last named means thereafter acting upon the bottom of the rod dropping below said predetermined point to cause said rod hoisting mechanism to lift the rod, to

cause said bell operating mechanism to dump the large bell and to resume dumping of the small bell after the large bell is returned to closed position and to cause said mechanism for dumping stock onto said small bell to resume operation.

5. In combination; a blast furnace having a small bell and a large bell at the top thereof, the large bell being arranged below the small bell to receive stock from the small bell; mechanism for dumping successive loads of stock onto the small bell; mechanism for operating said bells; means for causing said bell operating mechanism to open the small bell after a load has beendumped thereon and to reclose the small bell after the stock has been dumped therefrom onto the large bell; means for causing said bell operating mechanism to open the large bell after a predetermined number of loads have been dumped there on by the small bell and to reclose the large bell after the stock accumulated thereon has been dumped into the furnace; a rod extending downwardly into the. furnace at the top thereof hoisting mechanism for said rod; means for conoperation of said bell operating mechanism as the time arrives for operating the large bell to open the large bell and also the small bell upon its return to closed position after dumping said last of said predetermined number of loads onto the large bell and to stop operation of said mechanism for dumping stock onto the small bell after dumping another load onto the small bell after the small bell has dumped said last load onto the large bell, said last named means thereafter acting upon the bottom of the rod dropping below said predetermined point to cause said rod hoistin mechanism to lift the rod, to cause said bell operating mechanism to dump the large bell and to resume dumping of the small bell after the large bell is returned to closed position and to causesaid mechanism for dumping stock onto said small bell to resume operation.

FRANK 1.3mm.

Images