US2827864A - Self-seating furnace cover - Google Patents

Description

March 25, 1958 P. c. OSTERMAN ET AL 2,827,864

SELF-SEATING FURNACE COVER Filed June 1, 1955 INVENTORS PHILIP C.OSTERMAN ROBERT L. HATFIELD FIG.4.

ATTORNEY United Stats SELF-SEATING FURNACE COVER Application-Jamel, 1955, SerialNo. 512, 553

9 Claims. (Cl. 110-177) This invention relates in general to improvements in metallurgical heat treating furnaces and is concerned moreespecially with improvements in the covers and' cover-suspension and cover-operating means of furnaces of the vertical type.

Types of treating furnaces to which the invention is particularly adapted are normally cylindrical steel shells, but may be square or rectangular depending upon their particular. function, and linedywith fire brick or other heat insulating refractory. The heating chamber extends, generally vertically and is fired by burners strategically spaced about the periphery of the chamber. In some instances the burners are positioned tangentially so. as to give a swirl to the heated atmosphere.

Through the open top of such a furnace the Workpieces, individually or stacked, or in baskets, are lowered by means of a crane or air-hoist apparatus and the rela- .tively heavy cover replaced. If the Work is to be given a special gaseous treatment, such as carburizing, it is .placed within a retort and the whole assembly lowered into the heating chamber of the furnace. Thepipe connections that supply the retort with the gaseous atmosphere during the heating process must of necessity extend through the cover of the furnace.

The covers of the upright styles of furnaces are not only large in diameter, assumingthe furnace is round, but very heavy and difficult to manipulate. Theytoo are made. of firebn'ck or suitable refractory material and usually banded with iron to hold the individual brick .components of the cover together. A cover several inches thick and measuring 2 or more feet across is not uncommon .and presents a .difficult problem to move on and off the furnace to permitwork change, especially when the furnace is hot.

Prior .to this inventionthe cover was slid-laterally over the-furnace top. to an improvised shelf, and, in some instances the cover was pivoted so as to be slid over the ,top of the furnace and to one, side thereof. Such cover operating methods inaddition to necessitating a work area substantially twice the floor space of the furnace, were cumbersome, and excessively hard on the refractory materials of both-cover and furnace. Moreover, the

atentO abrasion and abuse the covers received soon rendered themill fitting and no'longer tight so that they soon needed replacement.

The present invention aims to render available an improved cover and cover-suspension means that eliminates I problems of abrasion, wear, and abuse, and by which the unifofm'ly and acquire a uniform treatment throughout.

Afurther aim of the invention is the economical =conr 2,827,864 Patented Mar. 25, 1958 struction ofa ruggedand serviceable cover assembly the operation-of whichprevents abuse and eliminates wear on the refractory members to the end of prolonging the useful life of the parts.. The invention also aims to provide ajcover construction and supporting means therefor that maybeconstructedof relatively fewparts and which is conveniently and expeditiously operable to permit accessto the heating chamber of furnace, which avoids theneed to disconnect retort connections, temperature controls and suchother externally connected devices that may be used within the furnace during a treating process, whenever the 'furnaceis opened or closed, and a cover suspension which is adjustable to fitthe top of the furnaceand thereafter automatically compensating and selfadjusting to minor irregularities in the refractory units so that when closed and in operating position the furnace chamber is elfectivelysealed against escape of fumes and the lossof heat.

In achieving the objectives of the. invention his proposed toconstruct a furnace cover in two sections and suspend or support each at-its approximate. gravimetric center. from an ,overarm .ina manner such as to provide a limited floating movement about transverse axes- Each arm aextends rearwardly across the top of the cover and the rear end thereof functions as a pivot point about :which the associated cover section is laterally movable.

The .overarm pivots are, in accordancewith the:ob.jec tive of avoiding wear on the refractories incident toslid- .ing brick-on-brick, .also constructed for pivotal movement about. a horizontal axis whereby it becomes possible to effect alifting .of the cover and aseparation thereof from the furnace proper before the-cover sections are swung laterally. By constructing the cover in two sections-and by providing an open-sided recess in one orboth sections along their "mating edges for the passage-of retortfittings, piping, etc., such connections need not be disturbed each time the cover is openedor closed. The tilting .of:each cover-section axisrmay be effected manually; however,- it is preferred to construct the parts for power actuation .as-by an air -cylinder, valve controlled, so as to :relieve the attendant :of the task ofliftingra heavy masswhile at the same time moving the mass laterally.

Other-objects and advantages will-be inpa-rt indicated in the following description and in part rendered apparent therefromin connection with the annexed drawlngs.

To enable others skilled in thewart sofully to apprehend the underlying features hereof that they may :embody the same in the various ways contemplated bythis invention, drawings depicting a preferred typical-con struction .have beenannexed as parts "of this disclosure and, in such drawingsg like characters of -referencedenote'corresponding parts throughout all thewiews, of which:

Fig. 1 ofthe drawings 'is' an elevation of a vertical vtfurnace embodying cover-constrnction and cover-suspension features of this invention.

Fig. 2 'is :a plan'viewzof the furnace of Pig. 1 illustrating theclosed position of the cover sections in :full'lines and the openposition thereof in dotted lines.

Fig. 3 isv a front view of the cover supporting means.

Fig; 4 is a rear view of the furnace illustrating :a preferred means for lifting both cover sections simultanea ously.

Referring more particularly to Fig. l of the drawings the furnace illustrated comprises essentially a body portion 10 in which aheating chamber 11 is provided. The chamber 11 may be heated in' any suitable manner such as :by oil or gas lbur-ners indicated at 12. The "furnace is lined about its sides and bottom with a heat insulating refractory '13. Workpieces to be heated or otherwise treated are lowered into :thetchamber 11 .from' thevtop'aud the opening closed by a refractory cover 14. Furnaces of this type are usually vented at the bottom by conventional means.

In accordance with the present invention, it is preferred to construct the cover 14 in two sections-A and B which when in abutting relation as shown in full lines in Fig. 2 completely cover the open end of theheating chamber with a generous overlap about the edges thereof. Each cover section is made of insulating refractory brick, preferably banded with iron or steel, andis overlaid with a pair of spaced angle irons 15 and 16. The pairs of angle irons extend preferably lengthwise and are suitably secured to their respective cover sections along lines that pass through the approximate center of their masses, and one angle iron 16 of each pair is made to extend well beyond the cover to function as a handle. 1

The space between the vertical walls of the angle irons of each pair of cover irons is adapted loosely to receive a relatively flat overarm 17 (18) that extends generally horizontally from a vertically adjustable pivot shaft 19 (20). Each shaft is journaled in an upper bearing 21 and a lower bearing 22, the latter having an adjustable vertical-thrust pivot in the form of an adjusting screw 23 and a jam nut 24. By adjusting the thrust pivot 23 in or out with relation to the lower bearing bracket 22, the pivot shaft 19 (or 20) may be adjusted up or down and correspondingly adjust the cover-carrying overarm 17 (18) up or down. Height-adjusting meansof this character enables one properly to fit the cover to the furnace, inasmuch as there is always the likelihood of variations in refractory thickness on assembling the furnace or cover sections.

Each of the overarms 17 and 18 is connected with its associated cover section in a manner as to permit a limited floating action of the cover. In the arrangement illustrated, the floating action is obtained by utilizing two pivot pins 25 and 26 which pass through the upstanding flanges of the angle irons and through the overarm 17 (18) that is loosely guided and confined in the space between. Preferably the outer hole 27 in each overarm bar is elongated so that the cover section may tip from front-to-back slightly about the rear pivot pin 25. Each cover section is also free to tip from side-to-side slightly by virtue of the limited clearance provided between the upstanding sides of the cover irons 15 and 16 and the overarms 17, (18) confined therebetween.

The journal bearings 21 and 22 of the pivotal shafts 19 and 20 are mounted upon a tilting frame 30 that in turn is mounted for oscillatory movement about an axis 31 located at the upper end of the frame. The axis 31 comprises a shaft member mounted in straps 32 secured to the furnace exterior near its top. The straps 32 extend along the outer sides of the tilting frame 30 and function as guide means therefor. A pair of similar straps 33 are located near the lower end of the furnace and extend along the outsides of the lower portions of the tilting frame and serve to guide the lower end thereof.

It will be seen from the foregoing that each cover section is suspended from an overarm at its approximate gravimetric center and has a limited universal movement relative to its support that enables it to be automatically self-seating and self-adjusting to any minor irregularity in the refractory of the furnace top. It will also be seen that a tilting of the carrier frame 30 from the position shown in full lines in Fig. 1, to the dotted line position, correspondingly rocks the pivot shafts 19 and 20 and their respective integral overarms 17 and 18 counterclockwise about the horizontal pivotal axis 31 and effects a lifting of the cover sections A and B bodily off the furnace top. When the cover has been lifted and physically separated from the top of the furnace proper, the cover extensions 16 may be grasped by the attendant and one or both cover sections swung laterally about the axes of the vertical pivot shafts 19 and 20 to positions indicated in dotted lines in Fig. 2. The furnace opening is closed 4 by manipulating the parts in the reverse order, i. e., the cover extensions 16 are first moved to closed position which places the cover sections A and B directly over the furnace opening, and then the carrier frame .36 is tilted to its full line position (Fig. 1) which lowers the self-seating cover sections on to the top of the furnace and in this way dragging or sliding the cover on the top of the furnace is effectively eliminated. It will be seen further that when the furnace is closed as in Fig. 1, the pivot shafts 19 and 2t? slant away from the furnace at their lower ends and makegreater than a right angle with the generally horizontal plane of the cover sections 14. When in such a position the weight of the cover sections tend to hold the sections in substantially closed position over the furnace opening. It will also be seen that by tipping or slanting each pivot shaft .20 inwardly toward each other at their lower ends as indicated in Figs. 2 and 4, a tilting of the frame 39 to cover-raising position causes the cover sections to tend to swing laterally in the direction of lean of the pivot shafts, to

tilted outwardly at their lower ends so that the covers tend to lean toward one another on being raised oif the furnace top and naturally tend to move toward furnaceclosed position. We prefer,-however, to mount the pivot shafts so that the covers tend to stay open and so that they are out ofthe way during work-change operations. To aid the attendant in centralizing the cover sections a fixed stop 35 may be secured to the furnace against which the cover arms 16 may abut when the furnace is closed or nearly closed. V Tilting of the above-carrier frame 30 may be effected in a suitable way as by manually-operated linkages or by power-operated means. In the form shown herein a power cylinder 40 is provided whose piston rod 41 connects with a link 42 that also pivotally connects with the carrier frame 39 as at 43. A reversing valve indicated at 44 may be provided at a convenient location for controlling the direction and extent of action of the power cylinder. With such an arrangement very little effort is now required on the part of the attendant to open or close the furnace and hence the operation may be performed quickly and with consequential savings in furnace heat and with marked improvement in the uniformity in quality of the heat treatment given to large pieces or to small pieces processed in bulk.

When work is to be treated in a gaseous atmosphere, the retort is lowered into the furnace and connections made to an external source of-treating gas. By utilizing a sectionized cover of this invention, an opening H may be provided in one or both mating sides of the cover sections adapted to surround the retort piping or connections and whereby the latter need not be disconnected each time the furnace is opened. This feature enables one not only to save considerable time in charging and recharging the furnace but such operations requiring a cooling of the work in the same atmosphere may be carried on merely by swinging open the cover and elevating the retort and its chargeof work as complete assembly and standing it aside to cool. Jointed or fiex= ible connections may be provided in the gas lines for this purpose, as will be understood, but they need not be disconnected or the gas turned off when the assembly is elevated out of the furnace.

Without further analysis, the foregoing will so fully reveal the gist of this invention that others can, by applying current knowledge, readily adapt it for various uti: lizations by retaining one or more of the features that, from the standpoint of theprior art, fairly constitute 5. essential characteristics of either the generic or specific aspects of this invention and, therefore, such adaptations should be, and are intended to be, comprehended within the meaning and range of equivalency of the following claims.

Having thus revealed this invention, we claim as new and desire to secure the following combinations and elements, or equivalents thereof, by Letters Patent of the United States:

1. In a furnace of the character described having generally vertically disposed side walls defining a heating chamber adapted to receive work to be heat treated and forming a work-receiving opening in the top thereof, the combination of movable closure means for the workreceiving opening comprising a pair of complementary cover sections normally positioned in abutting relation when in closed position over the work-receiving opening, means for supporting each cover section cantileverfashion in relation to the work-receiving opening comprising a shaft member journaled in relatively fixed bearings for movement about a generally vertical axis and an overarm integral with each shaft member, means mounting a cover section to each overarm, a frame structure mounted to said side walls for pivotal movement about an axis transverse to the axis of said shaft members for supporting the bearings for the shaft members, fluid means including a piston and cylinder operatively connected with the frame structure for tilting said frame structure about its pivotal axis whereby to effect arcuate movement of said shaft members and a corresponding arcuate movement of the cover sections relative to the top of the said side walls, and means thereafter operable to swing one or both cover sections laterally about the axis of its related shaft member to permit access to the heating chamber of the furnace.

2. The combination of claim 1 in which each cover section is pivotally connected to its overarm whereby each cover section is rendered independently movable and thereby automatically self-adjusting to the furnace,

and in which each of said cover-carrying shaft members are axially adjustable in said journal bearings to compensate for variations and irregularities in the mating faces of the cover sections and furnace top. w

3. In a materials heat-treating furnace having side walls defining a heating chamber and forming a work-receiving opening in the top thereof the combination of, a cover assembly adapted to close the work-receiving opening leading to the heating chamber of the furnace comprising a refractory cover member, means supporting said cover member cantilever-fashion over the work-receiving opening in the furnace including a shaft member mounted for pivotal movement about a substantially vertical axis, journal bearings for said shaft member, frame means mounting said journal bearings in axial alignment, means mounting said frame means for movement about a generally horizontal axis, and means for tilting said frame means about its said horizontal axis to effect a tilting of said cover-carrying shaft member and a lifting of the cover member generally vertically off the furnace walls whereby to permit the cover to swing laterally in the direction of lean of the axis of said shaft member to furnace-open position.

4. In a materials heat-treating furnace having a heating chamber and side walls defining said chamber and forming a work-receiving opening leading to said chamber the combination of a cover assembly adapted normally to rest on the side walls and to close said workreceiving opening comprising a refractory cover member, means supporting said cover member in cooperative rela tion with said opening and cantilever-fashion to the said side walls including a substantially vertical shaft member mounted for pivotal movement about its longitudinal axis, bearing means for said shaft, frame means mounted for movement about a generally horizontal axis for mounting said bearing means, means mounting said frame means to the said side walls for tilting movement about said generally horizontal axis so that when said frame means is tilted about its axis said shaft member is tilted and said cover member lifted off the side walls and rendared free to move laterally about the pivotal axis of said supporting shaft away from the work-receiving opening.

5. In a materials heat-treating furnace having a vertically disposed heating chamber and side walls defining said chamber and forming a work-receiving opening at the top of said chamber the combination of a cover assembly adapted normally to rest atop the side walls and to close said work-receiving opening comprising a pair of movable cover sections, means supporting each cover section in cooperative relation with said opening and cantilevenfashion to the said side walls including a shaft member for each section mounted for pivotal movement about a substantially vertical axis, bearing means for each of said shaft members, frame means mounting said bearing means, means mounting said frame means to the said side walls for tilting movement about a generally horizontal axis so that when said frame means is tilted about its axis said shafts are tilted and said cover sections are lifted 01f the side walls and are rendered free to move laterally away from the work-receiving opening about the pivotal axes of their respective supporting shaft members, and means for tilting said frame means.

6. The combination of claim 5 in which the means for supporting each cover section includes an arm member operatively connected with each shaft member and in which each cover section is pivotally connected to one of the arm members at the approximate center of mass of the cover section so that each cover section may move independently and relative to its arm member and thereby rendered self-adjusting to the furnace side walls.

7. The combination of claim 5 in which each of said cover-carrying shaft members is mounted in said frame means for axial adjustment relative thereto.

8. The combination of claim 5 in which at least one of said cover sections has an opening in its edge adjacent the other cover section through which a portion of the workpiece being treated may extend when the cover sections are in closed position.

9. In a materials heat-treating furnace having a vertical heating chamber and side walls defining said chamber and forming a work-receiving opening at the top of said chamber the combination of, a cover assembly adapted normally to rest on the top of the said side walls and to close said work-receiving opening comprising a pair of complementary cover members, means supporting each cover member in cooperative relation with said opening and cantilever-fashion including a shaft member for each cover member mounted for pivotal movement about a variably inclined axis and an overarm integral with each shaft member, operative connections between each cover member and one of said overarms, bearing means for each of said shaft members, frame means mounting said bearing means, means mounting said frame means to the said side walls for tilting movement about a generally horizontal axis so that when said frame means is itlted about said generally horizontal axis said shaft members are tilted to vertical positions and said cover members lifted off the side walls and rendered free to move laterally about the pivotal axis of said supporting shaft away from the work-receiving opening.

References Cited in the file of this patent UNITED STATES PATENTS 873,573 Markmann Dec. 10, 1907 1,073,912 Koch Sept. 23, 1913 1,930,323 South et a1; Sept. 16, 1930 2,097,932 McKee Nov. 2. 1937

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