US2119426A - Furnace construction - Google Patents

Description

FURNACE CONSTRUCTION Filed Sept. 13, 1935 6 Sheets-Sheet l r1 #NM/mmf Nq mi] WIH -.uf Q bw ,fk SQ ,.mwxx m ./k um. k am mw mw R A uw mw #M H!! I .l bm. WM mv mv mv mw Fw. YN Q IN VEN TOR.

May 31, 1938. P. H. Dol

JGLAS ET AL 2,119,426

FURNACE CONSTRUCTION Filed Se 6 Sheets-Sheet 2 May 31, 1938. P. H. DOUGLAS Er AL K 2,119,426

FURNACE CONSTRUCTION Filed Sept. 13, 1935 5 Sheets-Sheet 3 INVENTOR, /w/f. #5m/64,45

May 31, 1938. P. H. DOUGLAS ET AL 2,119,426

FURNACE CONSTRUCTION Filed Sept. l5, 1935 6 Sheets-Sheet 4 @n UM" p-zmwgm ATTO NEYS.

May 31, 1938.

FURNACE CONSTRUCTION Filed Sept. l5, 1935 FLg- 75 INVENTOR. PAUL 0006445 BY fof/N E'Paa'ses .Fly

P. H. DOUGLAS ET Ax. 2,119,426

e sheets-sheet 5 May 3,1, 1938.

P. H. DOUGLAS ET Al. 2,119,425

FUHNACE CONSTRUCTION Filed Sept. 15, 1935 6 Sheets-Sheet 6 Fig.

INVENTOR. Q @um aaaLns JEU/w 574705595 if@ 76M@ p ATTO EYS.

`resented Mey 31, 193s Paulll. Douglasv and John F. Rogers,

Heights. Ohio1 assignors to The Wellman 'cleveland Engif neering Company, Cleveland, Ohio, a corporation of Ohio Application September 13, 1935, Serial No. 40,458

i2 iaime.

'I'his invention relates to improvements in furnaces and particularly open .hearth furnaces. It

is especially adapted furnace charging process '179, filed June 21, 1935, for furnaces, in which application the present furnace improvements are briefly cation Serial No. 2'7, Method of charging referred to.

In our prior application Serial No,

for use in carrying out the described in our applihave described a cold metal charging process the purpose of which is to depart from the spoonfu method heretofore used in charging open hearth furnaces and to handle the cold metal charge jin relatively large bulk. According to this process,

' a large part of and preferably the entire cold metal charge required for the melting heat is deposited in the furnace -at one time or in one charging operation, thereby affording a more economical process as to power and fuel consumption, speed of operation, and maintenance cost of the charging equipment and furnace.

The charging process referred to above is carried out by charging equipment constituting the subject matter of a second companion application filed by us, Serial No. 36,990, filed August 20, 1935.

This charging equipment eliminates the use of the present small charging box with its transporting apparatus and utilizes instead a container of ample capacity to handle at one time a large part of if not the entire cold metal charge. It

employs a receptacle or pan with a exible rolling bottom having a oor or bottom area comparablewith that of the hearth area to -be charged and preferably substantially equal to the entire hearth area. This pan is adapted to be filled with cold metal at a convenient point generally remote from the charging machine or other main unit of the charging equipment, which layer during the charging operation is transferred to and progressively laid on the hearth, the discharge of the cold metal from the pan being such that the layer on the hearth approximates the thickness and area of the layer on the pan.l

The present furnace improvements involve certain modicationsin the structure at the front of the furnace, and the provision of an appropriately large door or removable furnace front which is adapted to close an opening equal substantially to the length of the hearth and adapted to the insertion of the pan of a charging machine of such dimensions that the entire hearth can be covered with cold metal in one charging operation, as stated above.

is therefore to provide a furnace having at the permit viduallyV operable doors, preferably a series of them, arranged at spaced points along the front for the purpose of supplying the hot metal charge and for inspection of and repairs to the furnace hearth; and to provide operating mechanism or mechanisms forthe movable furnace front and operating mechanisms for the individually operable doors carried by the furnace front which mechanisms are of such a nature that each mechanism can be operated independently of and without interfering with the other mechanisms.

Other objects and important features of novelty will appear from the detailed description of the invention which.A may be here briefly summarized as consisting in certain novel details of construction and combinations and arrangements of .parts which will be set forth in the appended claims.

In the accompanying sheets-of drawings wherein we have shown the preferred construction and a slight modification, v

Fig. l is a front elevation nace; i

Fig. 2 is a plan view of the same;

Fig. 3 is a cross-section taken through the center of the furnace substantially along the'line 3-3 of Fig. 1;

of the improved fur- Fig. 4 is a fragmentary cross-sectional view taken through the door opening of the center door of the removable furnace frort showing the dooropen;

Fig. 5 is a cross-sectional view through the front portion of the furnace substantially along the line 5-5 of Fig. 1, with the furnace front in closed or normal position:

Fig. 6 is an end view of the movable front shifting mechanism showing in outline a portion of the furnace; n

Figs. 'l and 8-are views similar to Fig. 5, Fig. 'l showing the removable front extracted from the front opening by horizontal or forward movement and Fig. 8 showing the removable front I the hearth, as already is protected all ends by columns 25 ported by this girder and by the rear columns a continuous rigid connection between one of the lifting `arms and the lifting beam which is moved vertically to shift the furnace front from the position shownI in Fig. 7 to the position shown in Fig. 8;

Fig. 10 is a view similar to Fig. 1 showing a front view of the furnace proper and some of the shifting mechanism for the removable front which is here shown in slightly modified form by being composed of relatively movable articulated sections;

Fig. 11 is a sectional view substantially along the line il-II of Fig. 10; v

Fig. 12 is, an enlarged fragmentary sectional view substantially along the line |2--I2 of Fig. 10;

Fig. 13v is a view lookingltoward the front of the joint illustrated in Fig. 12; and

Fig. 14 is a view similar to Fig. 5 but on a reduced scale showing certain partsv of the furnace front extracting mechanism for the sectional furnace front illustrated in Figs. 10 to 13.

Referring now to the drawings, the open hearth furnace may have the usual construction except for the novel construction provided at the front thereof including the long removable furnace door or front equal substantially to the length of parts including the individually operated doors carried thereby, the extracting and lifting mechanism. the operating mechanism for the individ- 1ual doors, and the framework at the top of the furnace which supports the motors and the like for shifting the individual doors and for extracting the furnace front.

In Fig. 3 the conventional hearth is shown at 28 and the usual arched roof at 2|. The long cold metal charging opening 22 (see particularly Figs. 7 and 8) inthe front'wall of the furnace around by a water-cooled hollow 23. 'I'he top portion of the 28 is an upper steel framework 21 on which are supported certain operating mechanisms for the furnace front and the individual doors vthereof (see particularly Figs. 2 and 3), as will be explained. later. With the upper front part of the furnace supported in this manner, theopening 22 is unobstructed from end to end.

'I'he furnace front illustrated in Figs. 1 to 9 is member including a watercooled hollow steel frame 28a supporting a brick lining 2lb, 'see particularly Fig. 5, the inner surface of which is fiush with the inside of the furnace wall when the front 28 is in its closed posltion. The furnace front, whether it is rigid from end to end or articulated sections, is designed to t closely within the water-cooled steel frame 23 at the front of the furnace. If desired, the inner sur- Afaces of the upper and lower walls and also the end walls may be on a'. taper or inwardly conversent to insure the close tting relationship between the furnace. front and the furnace front frame although this is a detail which may be modied as may be found necessary or desirable.

The close fitting' relationship of the furnace front in the stationary furnace front frame 23 of the furnace makes necessary or at least desirstated, with its associatedr or formed of relatively movable l able two distinct front shifting mechanisms,

namely, an extracting. mechanism which moves' the front 28 approximately horizontally out of the furnace opening (Fig. 7), and a lifting mechL anism which raises it vertically above the furnace opening to the position shown in Fig. 8.

Considering rst the extracting mechanism for the movable furnace front, it'is to be noted that this mechanism is of the parallel motion type composed of parts so arranged as to maintain the front in vertical position during the extracting motion. This parallel motion mechanism includes a plurality of upper uniformly spaced arms 29 (Figs. 1, 5, 7 and 8) which at their lower ends are pivotally connected at 30 (see particularly Fig. to the upper part of the frame 28a of the furnace vfront 28 and at their upper ends are secured to a pair of aligned rockervshafts 3| supported in bearings mounted on top of a lifting beam 32 which extends across the upper front part of the furnace and is designed to support the furnace front 28 and all of the lifting parts. The extracting mechanism includes also a seriesA of equally spaced lower arms 33 best shown in Figs. 1 and 5 winch arms at their lower ends are pivotally connected by pins 34 to the lower part of the front frame 28a and at their upper ends are connected by pivot pins 35 (Fig. 5) to brackets 36 which are secured to the bottom of the lifting beam'32. As will be seen particularly by reference to Fig. 1, the upperand lower arms 29 and 33 are arranged in pairs andthe arms of each pair are connected by adjustable connecting rods 31 which complete the parallel motion mechanism the four points of each parallelogram being apparent from Fig. v5. The two rocker shafts v3l are located on opposite sides of the center of the lifting beam 32 and operate in unison each shaft manipulating through the associated parallel motion units one-half of the furnace front 28. 'I'he two rocker shaft arrangement is preferred but obviously a single continuous shaft may be employed instead.

It will be observed that the outer ends of the.

rocker shafts 3| are provided with arms 38 which are fixed to the rocker shafts, these arms being Y provided at their lower ends with rollers 39 (see rocker arms 38 and the rocker shafts 3| and the consequent rocking movement of the rockerf shafts 3| through the parallel motion units composed of the arms 29 and 33 and the connecting rods 31 moves the furnace front 28 into and out of the furnace front opening 22. It mig-ht be here stated thatthe parallel motion mechanism is such that when the door is beingextracted it will be slightly'elevated while being moved .fprwardly in the extracting motion and slightlywlowered as it is moved rearwardly in the restoring motion, as is desired. This will be apparent by a comparison of the four points of the parallel motion unit shown in Fig. 5 with the corresponding points shown in Fig. 7.

When the furnace front is in its out or exing motion imparted to the arms 40 will shift the traeted positmn (Fig. 'n the operauhgvand guide arms 45 provide vertical guides upon which the rocker arm rollers `operate during the lifting motion (see Fig. 8) so that during this motion` the rocker arms 55 do not move in relation tothe other lifted parts and the only motion of the.v furnace front 28 is a vertical lift.

The upper ends of the rocker operating arms are connected by adjustable connecting rods 43 to two .'cranks 44 (Figs. '2, 6, 7, and 8) which cranks are mounted von the vouter ends of two shafts 45 which are carried in bearings on the upper framework 21 (see Fig. 2). These shafts 45 are aligned, as best shown in Fig. 2, and at their adjacent inner ends are connected to re ducing gearing arranged in housings 46 and driven by anelectric motor l41. The reducing gearing is preferably of the double-reduction type and runs in o'ii contained in the housings, and the motor will be equipped with a suitable brake indicated conventionally at 45 in Fig. 3, but these features are not material to theinvention.

Thus to extract the furnace front the motor 41 is energized and rotates the two shafts 45 through a half revolution so as to swing the cranks 44, 180 from the position shown in Fig. 6 (thefurnace front here being in normal or closed position, as in Fig. 5) to the position shown in Figs. 7 and 8. This rocks the operating arms 40. swinging them outwardly form the position shown in Fig. 6 to the position shown in Fig. '1, and this motion of the armsr 45 rocks the rocker arms 38 and the rocker shafts Il and actuates the several parallel motion units so as'to move the furnace front 28 from vits closed podtion shown in Fig. 5 to its extracted -position shown in Fig. 7. Obviously, a further rotation of a half revolution. given to shafts 45 and the consequent 180 swinging or rotation of the cranks. 44 will rock the operating arms -45 in the reverse direction and cause the furnace frontto be restored to normal or closed position.

Assuming that the furnace front has been extracted by being moved forwardly substantially horizontally (but slightly lifted) to the position shown in Fig. 7, it is nextl elevated and this is accomplished by the lifting mechanism next to be described.

The lifting beam 52 is adapted to be raised and lowered between a series of inner guides 45 (see Figs. 1, 5, and 9) secured to and extending vertically along the front of the supporting truss 24' and a pair of outer vertical guidesI (see Figs. 1, 6, and 9) secured to the truss 24 near its outer ends. The lifting beam J52 is raised and lowered by two substantially vertical links 5| (Figs. 1 and 6)*which at their upper ends are connected by pins 52 (see Fig. 9) to brackets 53 secured to the lower side of the' lifting beam 32 near its ends. These links extend downward through the charging door and at their lower ends are connected by pins 54 to two operating rocker arms 55 which are .equipped with counterweights 56 which balance the weight of thelifted parts to a point just permitting the lifting beam to lower by gravity on ixed stops 51 on the furnace supporting truss or girderl 24, thus insuring proper seating of the furnace front in the, furnace opening when the furnace` front is being replaced. The rocker arms are pivoted inter- Y mediate their ends on pins 58 in suitable supports 59 and are operated through adjustable connecting rodstll by twov cranks 6I (Fig. 6) which make a half revolution when raising the front and a half revolution in lowering it, thus definitely iix- 1 vided with a brick lining h (Fig. 3).

ing its upper and lower positions. The cranks 6I are mounted on the outer ends of two shafts 82 (Fig. 1) lournaled in bearings 55 `and terminating at the center in a speed reducing unit 54 driven by an electric motorj5'equipped with a suitable solenoid Jbrake 55. The cranks are equipped with counterweights 51 which, together with the rocker arm counterweights 55, balance practically all of the lifted and moving parts. 'I'herocker arm supports 59 and driving 'mechanism for the rocker arms are mounted on foundations at the ground level. It might bfe here mentioned that while the above described mechanism for raising and lowering the lifting beam is preferred, other means 'may be employed for this purpose. L

'I'he removable furnace front 28 is provided at spaced intervals with a centrally disposed hot Vmetal charging door and additional doors for observation and repairs spaced equally along the length of the furnace front. All these doors, which are designated by the reference character 68, are of the same general construction except that the central vhot metal door isppreferably made larger than the others to accommodate the pouringspout ofthe charging ladle. Each of these doors preferably consists of a hollow steel frame 68a arranged for water-cooling and pro- A small opening 68e in the lower part' of each door provided with an easily opened cover facilitates inspection of the furnace contents. Each of the doors 55' is suspended by a pair of suspension arms 59-lpivoted at 10 on the upper part of the furnace front frame 28a so that when the door is ,in closed position it rests by gravity against a slightly inclined surface around the door opening on the front side of the removable furnace iront so as to insure a tight closure in the opening operation. Each of the doors is operated by an independent motor driven mechanism supported on the upper furnace supporting frame mechanism 21 and consisting of a chain 1I which yis anchored-to the top of the door 55 and passes over a sheave 'l2 mounted on the lifting beam 32 (see Figs. 3 and 4), and passes to the crank 15 driven through a gear reduction unit 14 by an electric motor 15, best shown in Fig. 3, the motor being equipped with a solenoid or other brake. Each crank 15 is on a shaft provided with an arm 15 to which a counter-weight 11 is attached to relieve the gears and the motor ofthe peak load on the crank during the opening operation.

In the opening operation, the top of the door f swings outward and upward on the radius of the suspension arms 55 while the bottom is held close to the furnace front 25 by two rollers 15 mounted on opposite sides of the frame of the door 55 and operating in guides 19 provided on the furnace frontframe 25a.,the door being shown in opening or closing the front is automatic. For t example, while no attempt is here made to show the control mechanism including the electric circuits and switches, the following control mechanism operating in the manner described may be utilized. The operator will press an open" push button which starts the opening motion, the cranks NM making a half revolution, swinging the removable frort 28 out of the furnace opening. At the end of the extracting motion, electric 'switches operated automatically by the mechanism stop the extracting lmotion and start the lifting motion which continues until tle cranks 6| have made a half revolution and the furnace front has reached its full open or raised position, when another electric switch automatically stops the motion. In the closing operation, the operator presses a close push button and the above automatic operation is reversed. The'above described electrical control is preferred, but any other suitable control may be substituted therefor. Likewise. in operating the individual doors 68, an open push button may be pressed, and when the crank 13 corresponding to the operating mechanism for that particular door has made a half revolution, the motor is automatically stopped, and to close 'the door the operator will push the close button for the door, whereupon the motor 'I5 will again be energized, and when the crank I3 has made a half revolution, the motor will be automatically stopped.y

It was previously stated that the `removable furnace front may be a continuous rigid member or it may be composed of relatively movable or articulated sections. The latter construction may be desirable in order to secure a close fitting of the furnace front in case the furnace hearth or skew-back becomes warped out of alignment, in which event the furnace front when seatedwill conform substantially to the warped surfaceby the seating of the sections of the furnace front as individual units. That is to say; the furnace front will vbe capable of accommodating itself to any warping which may occur in the frame of the furnace structure into which the furnace front is adapted to be inserted.

In Figs. 10 to 14 a sectional removable furnace front is shown. The furnace front which is here designated 28e is divided vertically into a number of sections, in this instance ve sections, provided with water-cooled interlocking joints 28d best shown in Fig. 12. Each section or unit of this removable furnace front is preferably provided, as in the case of the rigid continuousV removable furnace front, with an outer watercooled frame 28e and an inner brick lining 28j. The adjacent sections of the furnace front 28e are connected together by horizontal links 80 best shown in Figs. 12 and 13, the ends of which links are connected byl vertical pins 8i to pairs of ears 82 lpiecting forwardly from the furnace front section. I'he sectional furnace front, aside from the fact that it is formed of relatively movable sections, is similar to the continuous front, as will be seen by a comparison of Figs. 1 and 10. The sectional furnace front is provided with individual doors which are preferably constructed and operated identically the same as' the doors of the removable front first described. Likewise, the extracting and lifting movements `oi the sectional furnace front correspond precisely with the extracting and .lifting movements of the rigid or continuous furnace front and the extracting and lifting mechanisms for the sectional furnace front are preferably the same in their action and they may be the same. also in construction except for certain slight modifications in the extracting mechanism. I'he extracting mechanism for the sectional furnace,

front differs fromthat of the continuous front only in the slightchange in the form of the upper extracting levers-29 and in the manner of connecting the lower ends of the upper and vlower l,extracting levers with the furnace front.v By

comparison of Figs. 5 and 14,.it willbe seenthat -the parts ofthe parallel motion extracting units are thesame in principle and arrangement, but

in Figs. 10 and 14 the upper arm or lever which corresponds to the upper arm 29 of the first construction is designated 29a, and the* lower arm correspondingto the arm 33 of the first construction is designated 33a. 'Ihe adjustable connecting rods corresponding to the rods 31 of the ilrst construction are designated 31a. The upper ends of the arms 29a are connected to shafts 3| similar to 'the shafts of the first construction and the upper ends of the lower arms 33a are lpivotally connected as before to the bottom of the lifting beam 32.. to the upper and lower arms respectively at points equidistant from the centers of the `con-- nections between the upper ends of these arms The connecting rods 31a are connected and their respective supporting vmembers so as to complete the parallelogram. In this instance, the lower ends of the upper and lower arms are connected differently to the removable furnace front than in the first construction. So that the extracting mechanism may not interfere with the proper -seating of the individual sections of the furnace front, equalizing connections are made l between the arms of the parallel motion extracting units and the sectional furnace front, and to that end the lower ends of the arms are connected to the links 80 (which connect the adjacent sections of the sectional front) by universal or ball and socket joints. Accordingly, the links 80 are provided centrally thereof with spherical seats 80a, see particularly Figs. 12 and 13, and the lower ends of the arms are provided with spherical sockets 80h which have a universal iit on the spherical seats. As shown in Fig.`12. each socket is composed of two parts one retained in place by a shoulder and the other by a keeper plate or any other equivalent means. Fig. 12. it will be seen that relative movement between the two adjacent sections of the furnace front does not interfere with the connection of the arms of the extracting mechanism nor will the latter interfere with any relative movement which may occur between the sections when the furnace front is being seated. As the upper and lower connecting links Ih are directly in line with each other, in order that there may be the necessary clearance and freedom of movement between the upper arms 29a andthe lower'arms 33a of the parallel motion extraction'units, the upper arms 29a are forked or bifurcated, as shown in Fig. 10.

As will be seen by reference to Figs. 10 and 11, and, as previously stated, the sectional furnace front is divided into five sections each having one of the individually movable doors 6l. 'I'hese doors will be operated in precisely the same manner as previously described. Likewise, Vit will be noted that while there are five sections or units inl the sectional front, there are in this instance. six parallel motion extraction units as in the construction-first described. 'Ihe arms of the four inner'extracting units shown in Fig. 10 are connected to equalizing links which connect the sections of the furnace front, while the arms of the two outer extracting units are similarlycon-v- By reference tonected to links which, however. in thesev two instances do not function to connect together sec-1 the other four extracting units. inasmuch as the individual door shifting mechanism for the sectional front may be the same as that first described, and inasmuch as the extracting and liftindividually opened, and have shown also a sectional front each section in this instance being provided with one of the individually movable doors, withthevarioussectionsconnectedtogether in a manner such that the entire furnace front with the individual doors may be moved into and out of the furnace opening the Asame as with the rigid continuous furnace front, we do not desire to be confined to the method of sectioning the furnace front here disclosed as the front may be sectioned and the sections Joined together in numerous other ways so as to admit of relative movement both horizontally and vertically between the sections when the front .is being seated to accommodate itself to any warping which may occur in the furnace and particularly in the stationaryframein which the front is seated.

Thus it will be seen that we have provided an open hearth furnace having a removable front which is substantially as long as the hearth and which can be readily extracted and lifted and restored in place so as to admit of the insertion of a charging pan or'other receptacle having a floor area similar in size to that of the furnace hearth. thus enabling the entire hearth to be covered with cold metal or other material in one charging operation, and, if desired, allowing the entire cold metal charge to be deposited on the hearth in a uniform manner in one' charging operation,'as described in our prior applications. At the same time, the furnace front is provided with hot metal and inspection doors arranged and functioning as in the usual open hearth furnace. The provision of a removable furnace front comparable in length with the yfurnace hearth and the provision thereon of individually movable doors similar to those now in use on the non-movable or permanent open hearth furnace front, the extracting and lifting mechanisms for the furnace front, and the operating mechanism for the various doors each capable of functioning without interference with the other, constitute features believed to be new individually considered or in combination.

While we have shown certain preferred constructions of the furnace. front itself and of the various operating mechanisms, we do not desire to be confined to the constructions or arrangements illustrated and described but aim-in our claims to cover all modications which do not involve a departure from the spirit and scope of the invention in its broadest aspects.

Havingthus described our invention, we claim: l. In an open hearth furnace having an opening at the front thereof corresponding substantially with the length of the hearth, a front movable as a single unit to open or close substantially the entire front opening, a beam extending transverselyabove said front opening, parallel motion linkage carried by vsaid beam and having operative connection with said front, and means for actuating said linkage to shift said front into or out of said opening by substantially parallel movement.

. 2. In an open hearth furnace having an opening at the front thereof substantially equal in length t the length of the hearth, a front movable as a single unit to open or close substantially the entire front opening, a beam extending transversely above said front opening, parallel motion linkage carried by said beam and comprising plvoted arms having connection with said front adjacent the top and bottom thereof, and means for actuating said linkage.

v3. In a furnace having an opening at the front thereof, a front movable to open or close said opening, a vertically movable lifting beam extending transversely above said front opening,

parallel motion linkage carried by said beam and having operative connection with said front, means for actuating said linkage to shift said` front into or out of said opening by substantially parallel movement, and lifting means connected with the beam for elevating the beam and the front. f v

4. In a furnace having an opening at the front thereof, a front movable to open or close said opening, a beam extending transversely above said front opening, parallel motion linkage -carried by said beam and having operative connection with said front for shifting the same into and out of said opening by substantially parallel movement, said linkage comprising arms pivoted adjacent the top and bottom of the beam and having connection respectively with said front adjacent the top and bottom thereof. and means for actua-ting the linkage.

5. In a. furnace having an opening at the front thereof, a removable front for closing said\ opening, a beam adjacent the front of the furnace and extending transversely over said opening, parallel motion linkage comprising upper and lower arms connected with the front adjacent the top and bottom thereof, vertically spaced pivot means connecting the arms with said beam including a rock shaft adapted to cause actuation of the linkage, and means for oscillating the rock shaft.

6. In a furnace having an opening at the front thereof,"a removable front for closing said opening, a vertically movable lifting beam adjacent the front of the furnace and extending transversely over said opening, parallel motion linkage comprising upper and lower arms connected with the front adjacent the top and bottom thereof,

vertically spaced pivot means `connecting 4the arms with said beam including a rock shaft adapted to cause -actuation of the linkage, means for oscillating the rock shaft, and lifting means connected with the beam for elevating the beam andthe front.

-'I. In a furnace having an opening at the front thereof, a removable front for closing said opening, a rock shaft adjacent the front of the fur-` nace and extending transversely over said opening, means for rocking said shaft, and parallelmotion linkage comprising pivoted arms connected with said front and adapted to be actuated by connection with said. beam and said front and adapted to be actuated by the rock shaft, lifting mechanism connected with the beam for elevating the beam and the front,vmeans providing a crank on said shaft, and a pivoted arm engageable with said crank for rocking said shaft and having guide means along which the `crank moves dur` ing elevating of the beam and'front..

9. An open hearth furnace having a long front opening, a frame denning said opening, a removable front adapted to be seated in said frame, said front comprising a plurality of sections and connecting means providing for relative movement between the sections, and means engaging said connecting means and operable to shift said front as a unit to open and close said opening.

10. An open hearth furnace having a long front opening, a frame deiining said opening, an articulated removable front adapted to be seated in said frame and comprising a plurality of sections having connecting links therebetween, and means having rockable connection with said links and operable to shift said front as a unit to open and close said opening.

11. An open hearth furnace having a front opening of substantial length, a front adapted to be movedas a unit to open or close the entire front opening, and means for moving the front to its open position by successive independent movements comprising an extracting mechanism connected with the front for moving it forwardly substantially horizontally out of the front opening and an elevatingmechanism operatively connected with the front for thereafter lifting it to clear said front opening.

12. An open hearth furnace having -a iront opening of substantial length, a front adapted to be moved as a unit to open `or-c1ose the entire front opening, means Vfor moving the front to its open position by successive independent movements comprising an extracting mechanism connected with the iront for moving it forwardly substantially horizontally out of the front opening and an elevating mechanism operatively'connected with the front for thereafter lifting it to clear said front opening, said front having a plurality of spaced individually movable doors thereon, and mechanism for selectively shifting the individual doors, the front actuating mechanism and the door actuating mechanism being operable independently and without interfering with each other.

PAUL H. DOUGLAS. JOHN F.

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