US2678813A - Industrial oven - Google Patents

Description

May 18, 1954 C. F. MAYER INDUSTRIAL OVEN 4 Sheets-Sheet 1 Filed July 8, 1952 .4 rra Awa ys May 18, 1954 c. F. MAYER INDUSTRIAL OVEN m 4 Sheets-Shet 2 Filed July a. 1952 v-j uvm/Ton.

614m EMA ya@ 5ML O1/lm rra RNE V5 May 18, 1954 c. F. MAYER INDUSTRIAL ovEN 4 Sheets-Sheet 3 Filed July 8, 1952 M T m w.

61ML F.' MAYM Aly Arran/vaya May 18, 1954 Filed July 8, 1952 C. F. MAYER INDUSTRIAL OVEN 4 Sheets-Sheet 4 INVENTo OWL FMA YER BY dmfcmw Arron/ways Patented May 1S, 1954 7 Claims.

This invention relates to industrial ovens, particularly of the class used in foundries and similar plants for drying freshly made cores and the green sand linings of ingot and other large and heavy mold flasks.

In ovens of the class referred to the work is supported upon portable racks or cars and, with the oven closed, heated gas (using the term in its broad sense to embrace air) is continually forced into the oven, and at least a major part of said gas is simultaneously withdrawn` reheated and recirculated, any remaining part being exhausted to the atmosphere and replaced by fresh air that is drawn into the system at one place or another, as about the heater as combustion air, and possibly elsewhere, as will be readily understood.

Hereto-fore the supply ducts, from which the heated gas is discharged directly into the oven, have been located along the side walls near the floor, and the so-called recirculating ducts and exhaust ducts have been situated within the oven adjacent the top thereof. This arrangement was doubtless dictated by the well known principle that warm air rises, and the obvious fact that such action is accelerated by the natural stack draft to which the exhaust ducts are subjected, sometimes augmented by the suction of an eX- haust fan or blower.

While such a circulating system has generally been regarded as satisfactory, its eiciency and reliability have been greatly impaired in many instances by damage to the supply ducts resulting from the said ducts being struck and deformed by p-arts of the work work has been improperly placed upon the cars, project too far beyond the sides of the conveyances. Lack of care in arranging the work on the cars and rough handling of the equipment, both of which contribute to the difficulty, are more or less prevalent in foundries, where the work that is being handled is usually very heavy and cumbersome.

The two principal objects of my invention are to improve the circulation, and the distribution and diiusion, of the hot gas through the oven thereby to .increase the efciency of the latter; and to arrange the ducts so that none is within reach of any part of the work with which the portable rac-ks or cars are loaded.

In the attainment of these objects I arrange the supply ducts, and the exhaust ducts, ii' any, at the top of the oven, and the recirculating ducts, each preferably in the form of a trench, below the floor level oi the oven.

doors, through the that, because the irri) A further and important advantage resulting from such a duct arrangement is the availability of substantially the full width of the oven space for work accommodation. To this end, the width of the door opening is made to correspond substantially to the internal transverse dimension of the oven. Accordingly, it will be seen that my invention provides maximum capacity relative to the external width of the oven.

I have said that the recirculating duct or ducts of my improved oven are belovT each des-irably in the form of a trench. It is a further object of my invention to house in such trench or trenches the car pulling means, which may take the conventional form of a pull-cable, or an endless chain.

While my invention is not particularly limited to ovens of the so-called car type, nor to ovens that are open at both ends, .l have chosen to so illustrate it herein; and although a lift door is preferable for closing an open end of the oven as herein shown, other kinds of doors may be employed.

rihe above enumerated objects and advantages, with others that will appear as this description proceeds, are attained in the embodiment of the invention illustrated in the accompanying drawings wherein like parts are designated by like reference numerals throughout the several views.

In the drawings,

Fig. l is a front elevational view oi an industrial oven constructed in accordance with the invention;

Fig. 2 is a plan view of the oven;

Fig. 3 is a sectional side elevation of the oven, the plane ci section being indicated by the line 3-3 of each of Figs. l, 2 and 4, the View being shortened to avoid further reduction of the scale to which it is drawn by breaking away the ends and insetting them beneath the major portion of the view;

Fig. 4 is a transverse section through the oven on the line flof each of Figs. 2 and 3, this view being drawn to a somewhat larger scale than the others.

The oven comprises a casingj designated generally by the reference numeral I, including a tcp wall 2 and side walls 3, the latter being shown as mounted upon curbs 5 that are integral with and rise from a floor 6 of suitable material, such as concrete. The walls 2 and 3 are illustrated in a conventional manner as being oi insulating material, and in practice they may be composed of panels of appropriate size that consist of sheet metal shells illed with suitable insulation the floor level,

u and held together by a structural iron fra-mework, all of which is well known to those familiar with this class of ovens, and, furthermore, has nothing to do with the invention at hand.

The casing I is shown as open at each end, entirely from one side wall to the other, and from the :door upwardly to a shallow drop wall or lintel 8. Thus, in the present form of the invention, the oven is provided with an entrance at one end and an exit at the other. Guides IO, which may be in the form of outwardly opening angles, rise from the floor on opposite sides of each end of the oven casing immediately adjacent thereto,

and arranged with its lateral edges within-fthe p posed guides It at each end of the oven casing is a door that is slightly greater in height thanthe opening with which it is associated. that is located at what may be regarded,` for the present purpose, as the entrance to t e'ovenfis..

designated I2, and the one located at the exit is designated I3. The door I2 .is insulated and-may beof the .same general .construction as the wall panels .above described. A .beam I-I extends between and is suitably connected tothe upper ends of the guides I0 of each pair, and mounted thereon are pillow blocks. or bearings I 5.wherein is journaleda shaft I6. It will be observed that the pillow .blocks or` bearings are arranged in pairs, and between those of each .pair is a sprocket I7 that is suitably securedagainst rotation to-the shaftV I6. A chainIB is engaged over each of the sprockets Il' and hasA one of itsends connected at i9 to the topf thedoor .I2 or..I3 and its other end anchored at toV thebeam. Hl. Riding within a depending loop of each chain, between the anchored `end thereof and. the corresponding sprocket I7, isa rotary guide. orspr cket 2I that has suitable connection with a counterweight 22. Said weight is shown as a bar that iscommonto allV of the chains located at the corresponding end of the oven. One end of the shaft is hasdriving connection, through suitable reduction gearing enclosed in a casing 25, with an electric motor 2l, said casing and motor being supported on a shelf 28 that extends laterally ,from the adjacent guide IIJ... Through the customary circuits and remote beioperated in.reverse directionsA to raise andV lower the correspondingdoor.

Located within the oven casing. adjacent the top wall 2 are supply ducts Bilanci 3 I., shown as of thesamecross sectional size Vand. shape, and .a4

somewhat narrower `supply duct 32. The ducts 30 and 3l are preferably tted withinthe top corners of the casing and extendfrom one endof the oven tonear the Aopposite end thereof. TheV duct 32 is of the same length as the ducts 30 and..

3l, and is desirably located substantially midway betweenrthe two. The duct 32 has outlet. openings 33 in its side walls, and similar openingsSA in its bottom wall, while the ducts lland 3l haveoutlet openings 35 in their inner vertical walls and relatively wide outlet openings '36 intheir bottom walls. In accordance with common practice, the outlet openingsv of the supply ducts are equipped with damper plates so that the quantity' The door the iioor alongside the oven casing, incidentally in axial alignment with a heater 42 of conventional type commonly used in connection with recirculating systems of industrial ovens. The

eater may be of the oil or gas fired variety to which ambient air is admitted for combustion purposes. The outlet of the heater communicates with the inlet of the impeller or blower 4I through a conduit 134. In order to conserve heat, the conduits 4f] and 44 and the casings of the impeller or blower il and heater 42 may be encased in insulating material, as indicated. An electric motor d5 is shown as having driving connection, through abelt 45, with the shaft 4'! of the impeller or blower 4I.

An exhaust duct 50, provided with inlet openingsv 5I, is .supported within and transversely of the oven casing in the horizontal plane of the previously described supply ducts and adjacent the entrance end of the oven. Obviously, the supply ducts may be made shorter, so .that another .-exhaust duct maybe located at the exit endof'the casing, if desired. An exhaustifan or blower .53 is shown as mountedon top of the oven casing. and the inlet thereof is placed in communication with the exhaust duct through a conduit 54 that extends through an opening in the top wall ofthe oven casing.. The outlet of thefan or blower .53r

opens into an exhaust stack 55. An electric motor.

56 has driving connection, through avbelt 51,'witl1 the. shaft 5B ofthe fan or blower 53.

Situated below the level of the floor 6, which desirably consists of a solid monolithic structure, and .opening through the `floor .into the interior of the oven casing, are relatively narrow elongated depressions or formations providingl trenches 60 that constitute recirculating ducts. Although I have shown two such trenches, one of .a somewhat larger capacity may be employed, in which. case it would vpreferably be located at about the. longitudinal center of the casing. This alternas.

tive arrangement is so obvious that specic illustration thereof is deemedunnecessary. The two trenches communicate with each other through a cross duct 62, and with the heater 42 through a subterranean conduit 63. The top of the cross duct 62 may be closed by extending the floor 6 thereover, or said cross duct may be open at the top. as are the trenches 6D. if additional capacity4 of the gas recirculating facilities is desired.

The trenches 6D extend substantially the full.

length of the oven casing, and each is shownas disposed centrally of a track composed of parallel The tracks.

rails G5 that are set into the iloor. may lead from the area of the foundry or plant where the cores are made'and the moldsare lined, to the oven and 'in'through the entrance end of the casing, and thence, through the exit end, to points of delivery.

Cars 66, whereon the work, designated Wis. loaded, traverse the rails S5 and, in the present instance, are propelled by car pulling means According to prevailing practice,`

designated 6l'. the means 67 may consist of pull-cables or endless chains, the latter being schematically illustrat-ed in the drawings. These chains are guided over sprockets or the like 69, housed in pits 70,'

and are driven by suitable power means (not shown) that may be located in one of the pits. Beyond the endsof the oven, the car pulling means or chains operate in relatively narrow channels in the floor oftheiplant. These chan-- nels merge with the trenches which, by reason of 'their location, provide especially appropriate accommodations .for the .car pulling means .sub-

stantially throughout the length of the oven. The upper and lower reaches of the endless chains are supported and guided throughout the length of the trenches by upwardly facing ohannel beams 12. These beams are connected together in properly spaced relation to each other, and are shown as supported from the bottom of the trenches, by upright members 13. Any selected number of plates 15 are adapted to be arranged in variable spaced relation to each other along the top of each trenchin the present embodiment on each side of the car pulling means 61, with their inner edges sustained by the structure composed of the channels 12 and members 13, and their outer edges supported by the floor 6, within rabbeted grooves thereof. The plates 15, by reason of the fact that they may be varied in number and spacing, constitute regulable means for changing the gas recovery capacity of the recirculating ducts or trenches.

Any suitable expedient may be employed for separably connecting the car pulling means 61 to a car. Means for this purpose is more or less schematically illustrated in the drawing as cornprising entering and receiving members 16 and 11, one carried by the chain and the other by a car.

In the use of the oven, the work W, illustrated as stacks of large mold lasks, is arranged on the cars so as to be properly spaced from the side walls of the oven and provide free circulation of the hot gas through and about the work. The cars are now moved into the oven by the car pulling means 61 and the doors l2 and i3 closed. With the gas heater 42 in operation, current is turned into the driving motors 45 and 56 of the impeller or blower 4l and the exhaust fan or blower 53, respectively. The hot gas from the heater will be drawn through the conduit M to the casing of the impeller dl and delivered under pressure through the duct 42 and cross ducts 38 to the supply ducts 3D, 3| and 32. For a better understanding of a practical application of the invention, it may be related that, in a typical installation, the heater is of six million B. t, u.

capacity, and, with the impeller M in operation, a static pressure of from 4 to 6 prevails in the oven. In fact, it requires a static pressure substantially within these limits to force the hot gas downward in opposition to the natural tendency of such gas to rise. It is evident from this that the hot gas within the oven is thoroughly diffused and eiectivelv distributed through and about the work and that the efficiency of the oven is accordingly very high. As previously explained, the

outlet openings of the supply ducts may be effectively regulated by the damper means associated with such openings in accordance with prevailing practice, and by virtue of the regulable means provided by the plates 15 for altering the recovery capacity of the recirculating ducts or trenches S0, such approximate percentage of the oven atmosphere as may be desired may be reheated and recirculated, the remaining percentage being carried off through the exhaust duct 5l! and stack 55. A practical ratio would be about '70% for reheating and recirculation and the remaining percentage for withdrawal, the latter being replaced by atmospheric air entering about the doors and through the heater 42 as combustion air. Some leakage will occur elsewhere, as through the channels wherein the car pulling means is housed exteriorly o the oven and which communicate with the recirculating ducts or trenches 60, as above explained.

At the conclusion of the drying period the doors are opened and the cars are withdrawn from the oven by the car pulling means, in the present instance through the exit end of the oven where the door i3 is located.

In addition to the high efficiency of the oven assured by my novel method of circulation and distribution of the hot gas, the duct arrangement affords maximum space for the accommodation of the work and eliminates all possibility of damage to the ducts from the cause above set forth; and although it is not entirely necessary, it is desirable to continually replace a part of the oven atmosphere with fresh air, as herein provided, in order that the recirculated gas be less contaminated by the vapors given off by the work.

Having thus described my invention, what I claim is:

1. An industrial oven comprising an open end casing including a solid floor, closure means for the open end of the casing supported for movement between open and closed positions, supply duct means situated adjacent the top of the casing for delivering heated gas directly thereto, a trench formation in the floor constituting recirculating duct means disposed below the floor level and opening through said level into the interior of the oven casing, gas heating means and gas impelling means communicatively connected together for the heating of the gas and for the circulation of the same therethrough and having a gas inlet and a gas outlet, conduit means communicatively connecting said gas outlet to said supply duct means, and further conduit means communicatively connecting the recirculating duct means to said gas inlet, whereby to draw gas from the oven casing through the recirculating duct means and move it through the heating means and return it under pressure to the oven casing through said supply duct means, parallel rails supported by the floor, one on each side of said trench formation, and extending out through the open end of the casing to provide a track on which cars may be moved into and out of the oven, and car moving means operating within said trench formation.

2. An industrial oven comprising an open end casing including a top wall, side walls and a solid monolithic floor, closure means for the open end of the casing supported for movement between open and closed positions, a plurality of intercommunicating supply ducts within the oven casing extending substantially the length thereof in close proximity to the top wall, each duct having outlet openings at closely spaced intervals throughout the length thereof for the discharge of gas into the oven, a relatively narrow trench formation in the floor constituting a recirculating duct situated below the floor level and extending substantially the length of the oven casing and opening into the oven through said level, gas heating means and gas impelling means communicatively connected together for the heating of the gas and for the circulation of the same therethrough and having a gas inlet and a gas outlet, conduit means communicatively connecting said gas outlet to the supply ducts, and further conduit means communicatively connecting the recirculating duct with said gas inlet, whereby to withdraw gas from the oven through the recirculating duct and move it through the heating means and return it under pressure to the oven through said supply ducts.

3. An industrial oven comprising the combination and arrangement of parts dened by claim aises-,s1 3:

2T andfin additionthereto, an' :exhaust Aduct extending'transverselyY of within the planeof the theends `thereof and having openings through which gas is admitted thereto from the oven, and suction means in communication with the exhaust duct.

4.' AnA industrial oven comprising' the combination 'and arrangement of parts delined by claim 1, and," in addition thereto, two series of loose plates adapted to beplaced across the top of the frecirculating ductin selected numberand spaced relation'to one another to regulate the gasrreceiving capacityl of the recirculating duct, andfmeans for supporting the two series of plates in laterally spaced relation to each other to ai-A ford :access therebetween to the car moving means.

5:'fAn industrial oven comprising an open end casing including a topk Wall, side walls and a solid monolithic iioor, ciosnre means for the open end of the-,casing supported for movement between open` andclosed positions, supply ducts within theA oven casing extending substantially the lengththereof in close proximity to the top wall ofztlie casing and having outlet openings for the delivery of gas to the oven, a track consisting of parallel 'rails supported by and within the floor withtheir top surfaces in substantially the plane thereollleading into the oven through the open endof the casing, a relatively narrow trench formation in the iioor constituting a recirculating duct below the oor level and situated substantially midway between the rails and extending substantially the length of the oven casing and opening into the oven through the floor level, gas heating means and gas impelling means communicatively connected together for the heating of A'the gas and for the circulation of the same therethrough and having a gas inlet and a gas outlet,conduit means communicatively connecting said gas outlet to the supply ducts, and further conduit means eommunicatively connecting the recirculating duct with said gas inlet, whereby tolwithdraw gas from the oven through the recirculating duct and move it through' the heating means and `return it under pressure to the oven through said supply ducts.

6.v An industrial oven comprising the combinationand arrangement or" parts dened by claim 5,v wherein the recirculating duct provides accommodations for means for moving cars into and out ofthe'oven along the said track and wherewith the oven. casing entirely supply ducts and beyond connections, car moving means comprisingnaf separable fdrivlnga linear element, a guiding and supportingstruc-L- ture for said car moving means situated'inthe recirculating duct substantially the sides thereof, a plurality of midway between' loose plates, and' means for supporting said plates at approxi'- mately iioor level in spaced relation to each other? and between said guiding and ture and the floor adjacent the sides .of the re-' circulating duct, said plates being changeable iinl supporting 'struce number and spacing thereby to constitute regue.

lable means by which the of the recirculating duct may be varied.

gas receiving capacity'.

7. An industrial oven comprising a casing int-A of the casing supported for movez-w intercommunicating supply ducts within'theoven:

casing extending substantially the length thereof 1n close proximity to the casing and the third being between said two, each duct having outlet open'.`

top wall, two ofwsaid substantially midway ings for delivery of gas to the oven, a trench, below the iioor level and extending substantially.

the length of the oven and through the floor,

opening into the oven gas heating means and'gas"` impelling means communicatively connected to-z gether for the heating of the gas and for the cir' culation of the same therethrough and havmg'a:

through the trench and move it throughthe heating means and lreturn it under pressure to" the oven through said supply ducts.

Reerermesv Cited in the le of this patent UNITED STATES PATENTS

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