US2709529A - Charging slabs into melting furnace - Google Patents

Description

May 31, 1955 A. J. KLEFF, JR., ET AL 2,709,529

CHARGING SLABS INTO MELTING FURNACE 1 Sheets-Sheet 1 Filed July 13, 1951 JNVENTORS: ARNOLD J KLEFF, JR. BY Fawn/v00 A. Mo/P/N ATTORNEY May 31, 1955 A. J. KLEFF, JR, ET AL 2,709,529

CHARGING SLABS INTO MELTING FURNACE Filed July 13, 1951 11 Sheets-Sheet 2 H 29 12/ m m. J

INVENTORSI ARA/0L0 J KLiFF, JR,

FERNANDO A. Mom/v BY A TTORNEY May 31, 1955 A. J. KLEFF, JR, ET AL 2,709,529

CHARGING SLABS INTO MELTING FURNACE Filed July 15, 1951 11 Sheets-Sheet 5 INVENTORS ARA/01.0 J KLEFF, JFK, y FERNANDO A. MGR/N ATTORNEY My 31, 1955 A. J. KLEFF, JR., ET AL 2,709,529

CHARGING SLABS INTO MELTING FURNACE Filed July 13, 1951 1,1 Sheets-Sheet 4 IN V EN TORS ARA 0L0 J. K 1. EFF, Ja, BY FERNANDO A. MOE/N A TTO/PNE Y May 31, 1955 A. J. KLEFF, JR., ETAL 2,709,529

CHARGING SLABS INTO MELTING FURNACE Filed Jul 13, 1951 11 Sheets-Sheet 5 FERNANDO 14. MOE/N v M K J D L 0 M A A TTORNE Y May 31, 1955 A. J. KLEFF, JR., ETAL 2,709,529

CHARGING SLABS INTO MELTING FURNACE l1 Sheets-Sheet 6 Filed July 13, 1951 mN J mfi W mUM m m W m m W w A fl/ NR RE A M A. J. KLEFF, JR., ETAL 2,709,529

CHARGING SLABS INTO MELTING FURNACE 11 Sheets-Sheet 7 Filed July 13, 1951 May 31, 1955 A. J. KLEFF, JR, E'I'AL 2,709,529

CHARGING SLABS INTO MELTING FURNACE Filed July 13, 1951 11 Sheets-Sheet 9 INVENTORS: ARNOLD J KLEFF, Jia. F ERNANDO A. Mom/v Wit ATTORNEY May 31, 1955 A. J. 'KLEFF, JR, ETAL 2,709,529

CHARGING SLABS INTO MELTING FURNACE Filed July 15, 1951 11 Sheet-Sheec 10 RM Q m %Z ,5 w%% nu ma r mf l IIIIHH ,PMWJ! W11 l h M MIMI WI wA [I mm RE u n v .i f n m x AF D W m u t w M u m m 2 M 0 Z x A v v 9 0 w A TTORNE Y May 31, 1955 A. J. KLEFF, JR., ETAL 2 CHARGING SLABS INTO MELTING FURNACE 4 Filed July 13, 1951 ll Sheets-Sheet ll F/XED AX/S INVENTORS: ARNOLD J fflE/ ok By FERNANDO A. Mam/v MKW ATTORNEY United States Patent 0 CHARGING SLABS INTO MELTING FURNACE Arnold J. Kleff, Jr., Towson, and Fernando A. Morin, Baltimore, Md., assignors to American smelting and Refining Company, New York, N. Y., a corporation of New Jersey Application July 13, 1951, Serial No. 236,648

9 Claims. (Cl. 214- 1s The invention relates to the charging of metal into electric melting furnaces and more particularly to a machine for charging copper cathodes into such a furnace, which machine lends itself to automatic operation.

In the use of an electric arc furnace for melting cop- 31 per for subsequent casting into molds, there are ap preciable advantages in operating the furnace so that the charging, melting and pouring take place simultaneously and continuously. This technique supplants the conventional practice using combustion type furnaces of first charging the metal to be melted, heating up the furnace and melting, skimming the consequent slags, blowing the charge, then poling to tough pitch copper, and pouring into molds.

The simultaneous charging, melting and pouring in a continuously closed furnace enables stable atmospheric conditions to be maintained, thus retarding the formation of slags, and eliminates the operations of blowing (oxidizing) and poling (deoxidizing).

According to a preferred form of the present in- An inclined elevator guide is supported in fixed position under said frame; on this guide is an elevator car riage adapted to carry the cathode or other metal slab and push it into a hatch in the frame in line with the furnace charge opening. The inclined guide also supports an auxiliary, or compensating, carriage which is yieldably held against the frame, regardless of angular adjustment of the frame. This auxiliary carriage carries the control mechanism by which the elevator carriage may be stopped in standby position before being raised into final position within the hatchway for disi charge of the cathode into the furnace.

Further, according to the invention, a magazine is conveniently provided for storing metal slabs to supply the elevator carriage. The magazine may comprise a pair of endless conveyors having straight reaches disposed parallel to each other and supporting a series of ledges or shelves. A feed chute is provided for feeding slabs, one by one, onto these ledges after which the magazine ascends to bring the next set of ledges into line with the feed chute. Descent of the elevator carriage causes operating members on the carriage to engage gates on the magazine permitting the uppermost slab in the magazine to slide out by gravity onto the carriage.

A suitable mechanism is provided for controlling the sequence of operations entirely automatically and under control of a suitable timing mechanism which can ill "ice

be set to feed the slabs into the furnace at a predetermined rate. Or, if desired, the machine may be manually operated by an operator utilizing remote control mechanism for manually controlling the several operations.

Referring now to the drawings for illustration of the preferred embodiment of the invention:

Fig. 1 is a side elevation of a charging machine, according to the invention. It shows how the cathode C slides into magazine B; elevator carriage D receives cathode from magazine and raises it to level with charging frame E; pushing devices 107 push cathode into furnace F;

Fig. 2 is a sectional elevation through the magazine B and illustrates how the cathodes C may slide onto the shelves or ledges 30;

Fig. 3 is a detail section taken on the line 33 of Fig. 2, illustrating how the gates 45' of the magazine B may be swung open to release the cathodes C;

Fig. 4 is a longitudinal section on the line 4-4 of Fig. 1, illustrating how the ledges 30 mounted on the endless chains support the several cathodes C;

Fig. 5 is a transverse section, taken on the line 5-5 of Fig. 2, illustrating the supporting structure for the endless chains of the magazine;

Fig. 6 is a diagram illustrating the manner in which the magazine B is driven;

Fig. 7 is an elevation of the elevator carriage D, illustrating how the arms 65 cooperate with the lugs 58 of the magazine gates 45 to open them;

Fig. 8 is a plan view of the elevator carriage, illustrating cooperation of arms 66 with the magazine gates 5;

Fig. 9 is a transverse section through the elevator carriage D taken on line 99 of Fig. 8;

Fig. 10 is a detail of a switch arm 91 on the elevator carriage D;

Fig. 11 is a side elevation of the elevator carriage D at the top of its movement;

Fig. 12 is a top plan view of the charging frame E showing cathode C in hatchway ready to be pushed into furnace;

Fig. 13 is a detail on the line 13-13 of Fig. 12, illustrating the pusher cylinder 108;

Fig. 14 is a section on the line i i-14 of Fig. 13;

Fig. 15 is a central section through the elevator carriage at its uppermost position, illustrating the position of the cathode C just before it is pushed into the furnace F by the pusher plate 107;

Fig. 16 is a section on the line 1616 of Fig. 15, illustrating the construction of the elevator carriage D and its cooperation with the charging frame E and related mechanism;

Fig. 17 is a vertical elevation illustrating mechanism on the charging frame for controlling the doors 12 and 13 of the furnace F; and

Fig. 18 is a diagrammatic detail illustrating the hydraulic cylinder and cable arrangement for operating the elevator carriage D.

General description The furnace charging machine will be, first, only generally described. As shown in Fig. l, a feed chute A allows cathode C to slide by gravity into magazine furnace P, whence the cathode C is pushed into the furnace.

it will be noted that the main axis or main lines of movement of the magazine B and elevator D are parallel to each other and inclined to vertical. The feed chute A and charge frame E are also inclined. This permits movement of the cathodes C between the several parts of the machine by gravity.

Furnace F may be a continuous, electric arc, melting furnace. it has a hydraulically operated support which raises and lowers the furnace about a pivot point indicated by 11. This pivot point is in line with the pouring spouts (not shown). The purpose of this construction is to permit the furnace to pivot about pivot axis 11, as indicated by arrow G, so as to keep the level of the molten bath even with the pouring spout. This takes care of small discrepancies between the rates at which metal is fed to and withdrawn from the furnace. The details of construction of this type of furnace are well known.

The cathodes C are flat slabs, as is well known, and may weigh in order of 200 pounds apiece. When the time comes to feed them into the furnace, gates 12 and 13 open automatically and the cathode is slid into the furnace through feed opening 9, as will be apparent from Fig. l.

The rate at which the cathodes are fed to the furnace will depend upon the rate at which molten metal is drawn off the furnace. For example, a 200 pound cathode may be fed every few minutes. cathodes per hour, for example, are fed to the furnace, this is at the rate of a ton per hour.

The general operation of the machine is as follows. (See Figure l.) Cathode C is released by stopper 16 whence it slides down feed chute A into magazine B. This starts ascent of magazine to bring the next shelf into line with chute A. As soon as the magazine stops, another cathode is fed into the magazine, and so on, until the magazine is filled with cathodes. The elevator carriage D descends until it engages the uppermost closed gate on the magazine, whereupon the uppermost cathode in the magazine slides onto the elevator carriage D. The elevator carriage D then ascends until it engages standby switch 144 which stops upward movement of the elevator until it is time for the furnace to receive another cathode. At this time the carriage D ascends the remaining distance until it registers with the frame E, at which time pusher cylinder 108 pushes the cathode into the furnace. All this will be described more in detail hereinafter.

Feed chute A The feed chute A will now be described in detail. As shown in Figs. l, 2, 4 and 5, it comprises side walls 14 terminating in wedge-shaped pieces 35 (Fig. 5) adjoining the ledges 30 of the magazine B. At the bottom is a pair of pipe rails 15 which extend all the way through the magazine. The feed chute A has a pivoted stopper 16 mounted on shaft 17 (Figs. 2 and 5) controlled by fluid cylinder 18. The. stopper or gate 16 prevents movement of cathode C into the magazine B while the magazine is moving. At the end of the feed chute A is a shock rail 19 to take the force of the heavy cathode as it slides into the magazine. Brake springs 20 are secured to the feed chute A to help retard the sliding movement of the cathodes. The upper edge of shock rail 19 is inclined (see Fig. 2) to release the oathodes C, permitting them to slide against their gates 45 as the magazine ascends.

Magazine B The magazine B will now be described. As shown particularly in Figs. 2 to 6, it comprises two main endless chain conveyor assemblies mounted on a suitable framework. Since the conveyor assemblies are identi- If ten 200 pound cal, it is only necessary to describe one in detail. An assembled frame 21 (Fig. 4) supports an upper shaft 22 and a lower shaft 23. These shafts in turn support sprockets 24 and 25 which in turn support chains 26.

Each chain is made up of flight links 27 and connecting links 28. The flight links 27 support flight plates 29 each of which has three ledges or shelves 30 to support the cathode C. The pivots of the chain support rollers 31 which roll on tracks 32 attached to frame 21 (see Fig. 5). The flight plates 29 support flanged wheels 33 which roll on tracks 34 also attached to magazine frame 21. Tracks 32 and 34 are for the purpose of holding the conveyors in position, help support the weight thereof and prevent sagging.

The opposed shelves 30 are aligned along the straight reaches of their respective conveyors; and carry upwardly, and store, a series of cathodes bridged across the ledges or shelves as shown in Fig. 4.

The magazine is driven as shown in the diagram of Fig. 6. Here chains 37 drive the upper shafts 22. Chains 37 are driven by speed reducers 38. Electric motor 39 drives adjustable drive 46 which in turn drives belt 41; this in turn drives reducer 42, which in turn drives reducers 38. It will be understood that the magazine moves very slowly, step-by-step, to bring its ledges or shelves 30, successively, into register with the feed chute A.

To hold the cathodes on their shelves on the magazine, each ledge 30 has a gate 45see particularly Fig. 3. Gate 45 has a forked end secured to hinge 46. A lock sector 47 is located on flight plate 29, between the forked end, and has recesses 48 to receive spring pressed detent 49. The gate has a lug 50 which is engaged by a member on the elevator carriage, as described later, which swings the gate to open position as indicated by the arrow in Fig. 3.

The magazine B has certain controls for automatic operation. See Figs. 2 and 5. Cam 53 is pivoted at 54 and has a spring pressed plunger 55 for holding the cam 53 in projected position. Cam 53 has a surface operating upon a roller 57 on switch 55. As cathode C slides into the magazine, it depresses cam 53 which closes switch 56. This starts the magazine motor 39 which raises the magazine until the cathode clears cam 53 at which time switch 56 opens and the magazine stops moving. Switch 56 also operates mechanism to energize fluid cylinder 13 to move gates 16 (Fig. 2) into downward position; this prevents cathode C from sliding into the magazine While it is moving.

To prevent overloading the magazine B, switch 51 is mounted on the framework, and carries lever 52 which is disposed in the path of the cathodes C. (Sec Figs. 1 and 4.) Engagement of lever 52 by uppermost cathode C operates switch 51; this stops motor 39 and operates cylinder 18 to close gates 1.6.

The magazine has a series of fixed cams 79, and 81 (Fig. 4) which cooperate with the lugs on magazine gates 45 to control their position. it will e understood that always the gates holding the uppermost cathode C in the magazine 13 are opened by the descending elevator carriage D. Thus, as the ascending shelves 3%) reach the ends of their straight paths and approach their curved paths around their upper sprockets 24, their gates 45 are in open position. The upper fixed cam 79 operates to hold the gates open as they pass around the upper sprockets. Fixed cam 83 operates to close the gates on their way down. The lower fixed cam 31 operates to hold the gates closed as they pass around their lower sprockets and ascend to a position in register with feed chute A where their shelves receive cathodes.

Elevator carriage D The elevator carriage D will now be described. It slides up and down on inclined ways 53 (see Figs. 1, 7 to 9, l5). Carriage D is made up of structural members forming in eifect long shoes 59 which slide on the ways 58 (see Figs. 8 and 11); platform having bottom pipe rails 60; and side walls 61 (see especially Fig. 8). A frame, indicated in general by 62, holds the several parts together. The carriage D has retarding springs 64 which bear against the cathode to slow down the cathode as it slides onto the pipe rails 60. Fixed shock posts 63 are provided (see Fig. 8) in line with guideways 58 to take the force of the moving cathode as it slides onto the elevator carriage, thus relieving lugs 83 on holding arms 82.

The carriage D carries mechanism for operating the gates of the magazine. As shown particularly in Figs. 7 and 8, the gate operators comprise arms 66 vertically movable about pivots 68 and having lugs 67 which engage lugs on the gates. Arms 66 are pivoted on swingable arms 69 which are pivoted at 70 to the carriage frame. Thus operator arms 66 can swing both longitudinally and transversely. Arms 69 have plates 65 carrying switches 71 having rollers 72. Arms 66 have cams 73 engaging rollers 72 to operate switches 71.

The operator arms 66 are swung laterally by a servocylinder 74- (Fig. 8) mounted on the frame of the carriage D. Fluid cylinder 74 has a crosshead 75 to which are pivoted rods 76; these in turn are pivoted to arms 77 on the shafts 70 on which the arms 69 are also mounted. An adjustable stop 78 (Fig. 8) limits the outward movement of crosshead 75.

The gate operators work in general as follows. As the carriage D descends, the opener lugs 67 engage the gate lugus 50 of the uppermost pair of closed gates.

Further downward movement of the carriage causes the arms 66 to swing upwardly causing cams 73 to engage rollers 72 to operate switches 71. Operation of switch 71 stops the carriage and acts to admit fluid to cylinder 74 which swings the arms 66 to the dot and dash positions shown in Fig. 8. This moves the gates 45 to open position, as shown in dot and dash lines in Fig. 8, permitting cathode C to slide onto the elevator carriage D.

Carriage D is provided with a pair of holder arms 82 (see Figs. 8 and 9). These holders have lugs 83 which act to hold the cathodes after t.e carriage has ascended to move the cathodes clear of shock posts 63. Arms 82 are mounted on shaft 84 which also supports arm 85 (Fig. 9) which forms part of spring assembly 86 which normally holds arms 82 in upper position. Shaft 84 also supports an outside lever 87 which moves the holding arms 82 down at the proper time, as explained hereinafter. Shaft 84 also supports a switch arm 88 engageable with a switch earn 89 of switch 90 mounted on carriage D.

As the cathode slides into position on carriage D, it depresses arms 82 which operate switch 90; this starts the elevator carriage upwardly.

Carriage D also carries a pivoted switch arm 91 (see Fig. 10) having a pin 92. Pin 92 engages cams 146 and 147 of switches 144 and 145 (Figs. 11 and 16) to stop the ascent of the carriage at standby position and at final position, as explained below.

The mechanism for driving the carriage D is as follows. Referring particularly to Figs. 15, 16 and 18, a hydraulic cylinder 95 is secured to the fixed framework. Cylinder 95 has rod 96 which carries a crosshead 98. Crosshead 98 slides on fixed rails and supports a series of four sheaves 97. There are also four upper sheaves 100 journaled on the fixed frame. A saddle 101 is secured to the lower part of the elevator carriage frame. A cable 102 has its ends secured to fixed anchors 99 (Fig. 18). The cable passes over the sheaves 97 and 100, as shown, and is secured around the saddle 101. Due to the multiple pulley construction, a given movement of hydraulic piston rod 96 will result in a multiplied movement of the elevator carriage D. Downward movement of piston rod 96 moves the carriage D upwardly.

Charge frame E The charge frame B will now be described. Referring 5 control and to semi and fully automatic control.

6 to Figs. 1, l2 and 15, the open framework is denoted generally by 165. This is secured fast to the furnace F and moves therewith about pivot 11. Frame 105 has a hatch opening to receive the carriage. See position of cathode C in Fig. 12. Frame 105 carries cantilever springs 106 which bear against the cathode C as the carriage D moves upward into charge position. See Fig. 15.

The charge frame E carries the pusher assembly. See particularly Figs. 12 to 14. Pusher plate 107 is secured to piston rod 109 of fluid cylinder 108. An auxiliary rod 110 is secured to pusher plate 107 and carries a crosshead 111 slidable on the way 115. Crosshead 111 has a lug 112 which engages lever 113 on switch 114 for the purpose hereinafter described. Pusher plate 107 engages cathode C to push it into the furnace.

The furnace F is provided with a special vestibule wall 117. See particularly Figs. l, ll, 15 and 17. The furnace has an inner gate 12 and an outer gate 13. See Fig. 17. The inner gate 12 is pivoted on shaft 118 and the outer gate 13 is pivoted on shaft 119. Arm 116 on shaft 119 and arm 121 on shaft 118 are connected by rod 122. An operating cylinder has its piston rod connected to arm 121. Thus operation of cylinder 120 operates to open both gates 12 and 13 in the direction of the arrows shown in Fig. 17. The double gate and vestibule provides a sealing construction to conserve heat. The gates are opened for the purpose of charging a cathode in a furnace.

The vestibule has side walls 123 and bottom pipe slides 124 for guiding the cathodes through the vestibule into the furnace. It also has a safety feeler lever 125 pivoted to shaft 126 and held by a spring normally in the path of the cathode. See Fig. 17. Shaft 126 supports cam 127 which operates one or more switches 128, 129, 130 for a purpose described more in detail below.

compensator The compensator will now be described. This construction is necessary to take care of the angular movement of the charge frame E with respect to the fixed elevator slide rails 58. As shown in Figs. l1, l2 and 16, a special way 134 is welded to the top of one of the carriage slide rails 58. An auxiliary carriage 135 is slidably mounted on the special way 134. Slide 135 carries a roller 136 engaging a plate 137 on frame 105. An air cylinder 138 having a rod 139 secured to slide 135 permanently holds the latter up, with the roll 136 pressing against plate 137; therefore, even though the charge frame E is angularly moved up and down, it maintains a constant relationship to carriage 135 and the control members mounted thereon, as hereinafter described.

Slide 135 carries pin 141 which is engaged by arm 87 as the elevator carriage D ascends to charge position to depress the cathode holding arms 82. Slide 135 also carries standby switch 144 and final switch 145. These switches have cams 146 and 147 which are operated by pin 92 on arm 91 to stop ascent of the car'- riage. Engagement of pin 92 with cam 146 stops the elevator carriage in standby position; engagement of pin 92 with cam 147 stops the elevator carriage in final or charge position.

Operation and controls The above construction lends itself both to manual In the case of fully automatic control, a suitable timer (not shown) may be provided which may be set to feed any predetermined number of cathodes per hour into the furnace. It will be understood that suitable electric and electro-hydraulic, or electro-pneumatic, automatic mechanism (not shown) may be provided for controlling the various servo mechanisms operating the various steps of the process executed by the machine.

The operation of the several electric switches and other controls will be explained by tracing the path of a cathode as it passes through the machine from the feed chute A into the furnace F.

A workman properly prepares the cathodes C and places them manually, one by one, on the feed chute A. The pivoted gate 16 acts to prevent the introduction of a cathode into the magazine B while it is moving. If the magazine is stationary, the cathode C slides onto the lowermost shelves or ledges of the parallel reaches of the magazine conveyors, in register with the feed chute.

The sliding of cathode C into the magazine B operates cam 53 (Fig. 2) which operates switch 56; closing of switch 56 starts the magazine motor 39 (to elevate the magazine) and operates cylinder 18 to close gate 16. The release of cam 53 by the rising of cathode C opens switch 56; opening of switch 56 stops the magazine motor and operates cylinder 18 to open gate 16.

This operation will continue as long as cathodes are fed to the feed chute A. A special limiting device (51, 52) is provided to prevent admission of further cathodes into the magazine when it is completely filled.

It will now be assumed that a cathode has been delivered into the furnace. This initiates descent of the elevator carriage D as described below. The descent of the elevator carriage D (see Fig. 7) causes the lugs 67 on arms 66 to engage lugs on the magazine gates 45 (Figs. 7 and 8), thereby raising arms 66 with respect to the carriage D. This causes the cam 73 to engage roller 72 to operate switch 71. This operates the elevator cylinder 95 to stop the elevator carriage, and operates cylinder 74 which swings the arms 69 to open magazine gates 45. It will be understood that the aforementioned engagement between arms 66 and gates 45 will occur at the highest shelf carrying a cathode; all shelves above have discharged their cathodes and their gates are open and out of register with the arms 66 on the descending carriage.

Opening the magazine gates permits the cathode C to slide onto the carriage, depressing arms 82 (Figs. 8 and 9). Depression of arms 82 operates switch cam 89 on switch 90 which operates elevator cylinder to start the carriage ascending.

The carriage ascends until pin 92 (Fig. 7) engages earn 146 (Fig. 11) of standby switch 144. This stops the elevator carriage at standby position where it remains until the timer (not shown) starts it up again at the right time, as determined by the rate at which cathodes are to be fed into the furnace.

Upon resumption of elevator carriage ascent, the ascent continues until pin 92 hits the switch cam (Fig. 11) of limit switch 145; this stops the carriage. At the same time outside lever 87 hits pin 141 to release the cathode.

The limit switch 145 also operates the door opening cylinder (Fig. 17) and operates the pusher cylinder 108 (Fig. 12). The heavy leaf springs 106, bearing against the cathode, delay the pusher cylinder until the furnace doors open, after which pusher cylinder pushes the cathode through the open doors into the furnace.

Passage of the cathode into the furnace operates the safety feeler this operates switches 128, 129 and 130; this re-sets the timer and also operates a signal if there is any obstruction preventing discharge of the cathode into the furnace.

When pusher cylinder 108 is advanced all the way, its lug 112 operates switch 114. This operates elevator cylinder 95 to initiate descent of the elevator carriage, it operates the door opening cylinder 120 to close the furnace doors, and operates the pusher cylinder to return the pusher.

It will be understood that instead of the various events being operated automatically, a workman could be provided with a series of remote controls to operate the several servo cylinders, and that each event could be controlled by the workman operating the proper control at the right time. Also if desired, instead of feeding slabs one at a time, to feed chute A, two or more slabs arranged in a pile may be fed, pile-by-pile. It will be understood that these small piles will, in effect, be acted upon by the machine as a single slab. In the claims the term slab or equivalent term is intended to include either a single slab or a pile of slabs acting as a single slab.

Comments Among the advantages of the present invention are the following: the operation of the electric arc furnace is improved by uniform rate of charging cold metal into the furnace. Stable atmospheric conditions within the furnace are maintained by reducing the time during which the charging gates are open and by controlling them automatically. The uninterrupted input and consequent output of molten metal due to the displacement by the charged slabs prevents formation of a stagnant bath of molten metal, and the absorption of impurities from furnace gases is thus reduced to a minimum. The furnace operator has greater flexibility in that he can speed up or slow down the charging rate as desired without being concerned with the rate at which cathodes are prepared for the furnace. The provision of the standby position brings the slabs into charging position always under the same conditions. The compensating arrangement permits the furnace to be adjusted while the carriage is in standby position. The standby position being adjacent to the final or charging position, the compensating device facilitates the final step of placing the cathode into the hatch on the frame where it can he pushed into the furnace.

What is claimed is:

. i. In a charging machine for feeding flat slabs into a. melting furnace, the wall of the furnace having a charge slot, a fixed elevator guideway, an elevator carriage slidable on said guideway, a magazine along side said guideway, said magazine having conveyor supports for supporting a column of slabs, means for feeding slabs into the bottom of said magazine, means for trans ferring slabs from the top of the magazine to said elevator carriage, and means for transferring slabs from the elevator carriage into said charge slot.

2. In a charging machine for feeding flat slabs into a melting furnace, said furnace having a horizontal axis of rotation, an adjustable support for the furnace to rotate the furnace about said axis and thereby to adjust the level of molten metal, a charge frame aflixed to said furnace and movable therewith about said axis, the wall of said furnace having a charge slot adjacent said frame, a fixed elevator guideway substantially perpendicular to said frame, a compensator carrier on said guideway, means holding said compensator carrier to move with said frame, an elevator carriage slidable on said guideway, said charge frame having a hatchway into which said elevator pushes a slab, a pusher element on said frame for pushing said slab through said furnace discharge slot, first and second control devices on said carrier, means on said carriage engageable with said first control device for stopping said carriage in standby position, means on said carriage engageable with said second control device for stopping said carriage in position for discharge of said slab into said furnace.

3. In a charging machine for feeding fiat slabs into a melting furnace, a charge frame aflixed to said furnace, the wall of said furnace having a charge slot adjacent said frame, a door pivoted to the furnace wall at said charge slot, a fixed elevator guideway substantially perpendicular to said frame, an elevator carriage slidable on said guideway, a magazine comprising a pair of endless conveyors having their straight reaches opposed and parallel to each other, said conveyors having ledges to support said slabs between said straight reaches, said magazine having its axis of movement substantially parallel to said elevator guideway, a charge path disposed on the opposite side of said magazine from said elevator guideway, gates secured to said ledges, operators greases on said elevator carriage for engaging said ates upon descent of said carriage, means on said carriage for swinging said operators to open said gates, said charge frame having a hatchway into which said elevator pushes a slab, and a pusher element on said frame for pushing said slab through said furnace discharge slot.

4. In a charging machine for feeding flat slabs into a melting furnace, said furnace having a horizontal axis of rotation near one side thereof, an adjustable support for the furnace to rotate the furnace about said axis and thereby to adlust the level of molten metal, a charge frame affixed to said furnace and movable therewith about said axis, the wall of said furnace having a charge slot adjacent said frame, a vestibule around said charge slot, said vestibule having an opening, a door pivoted to the furnace Wall at said charge slot, a second door pivoted to said vestibule at said vestibule opening, a fixed elevator guideway inclined to vertical and substantially perpendicular to said frame, a compensator carrier on said guideway, means holding said compensator carrier against said frame, an elevator carriage slidable on said guideway, a magazine comprising a pair of endless conveyors having their straight reaches opposed and parallel to each other, said conveyors having ledges to support said slabs between said straight reaches, said magazine having its axis of movement substantially parallel to said elevator guideway, a charge chute disposed on the opposite side of said magazine from said elevator guideway, gates secured to said ledges, operators on said elevator carriage for engaging said gates upon descent of said carriage, means on said carriage for swinging said operators to open said gates, said charge frame having a hatchway into which said elevator pushes a slab, a pusher element on said frame for pushing said slab through said furnace charge slot.

5. in a charging machine for feeding flat slabs into a furnace, the wall of said furnace having a charge opening, an elevator guideway, an elevator carriage movable on said guideway, a magazine comprising a pair of endless conveyors having their straight reaches opposed and parallel to each other, said conveyors having ledges to support said slabs between said straight reaches, said magazine having its axis of movement substantially parallel to said elevator guideway, a charge path for feeding slabs to said magazine, said carriage receiving slabs from said magazine and delivering them to said charge opening.

6. In a charging machine for feeding pieces into a melting furnace, means for tilting said furnace about a horizontal axis, a charge frame affixed to said furnace and movable therewith about said axis, said furnace hav- .1

"1g a charge opening adjacent said frame, a fixed guide device adjacent said frame, a compensator carrier movable on said guide device, means causing said carrier to move with said frame, a carriage movable on said guide device, first and second control devices on said carrier, means on said carriage engageable With said first control device to stop said carriage in standby position, means on said carriage engageable with said second control device to stop said carriage in position for discharge of said pieces into said furnace.

7. Apparatus for charging a melting furnace with metal slabs, said furnace having a charge slot Whose axis is inclined to true horizontal, said apparatus comprising a storage magazine for a column of said slabs, said magazine having spaced supports for said slabs, said supports being disposed on an. inclined main longitudinal axis, which axis is nearer vertical than horizontal, said supports having supporting surfaces extending transversely to said main longitudinal axis so that the slabs on said supports are in planes inclined nearer horizontal than vertical, the incline being sufficient to cause the slabs to tend to slide off their supports by gravity, said supports being axially spaced apart but in close proximity so as to individually support a closely spaced column of slabs, stops on said supports to hold said slabs in positions they occupy in said magazine, a receiving conveyor, means to move said receiving conveyor to bring it into register with a particular support, means for removing the stop on the registered support to permit the selected slab to slide by gravity off its support onto said receiving conveyor, and means for feeding the conveyor slab into said furnace slot.

8. Apparatus according to claim 7 comprising also a feed chute inclined to true horizontal, an additional stop to hold a slab in position on said feed chute, and means for removing said last-mentioned stop to permit said slab to slide by gravity onto a support on said magazine, and means for moving said magazine step-by-step to bring said supports successively into registry with said feed chute.

9. in a charging machine for feeding slabs to be melted into a melting apparatus, a storage magazine defining a column, said magazine having supports for storing a column of said slabs along its main longitudinal axis, said magazine receiving slabs independently of demand of said melting apparatus, a traveling receiving conveyor for carrying, along its main longitudinal axis of travel, said slabs from said magazine to said melting apparatus as required by the melting apparatus, the main longitudinal axes of said magazine and receiving conveyor being generally parallel, said supports and said receiving conveyor having supporting surfaces extending transversely to said main axes, means for bringing said receiving conveyor into register With one of a plurality of said supports on which a slab is stored, and means including said support effecting edgewise movement of the slab When a force is applied thereto onto said receiving conveyor while said support and receiving conveyor are in register.

References Cited in the file of this patent UNITED STATES PATENTS

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