US 3058732 A
Description (OCR text may contain errors)
16, 1962 c. H. BARNETT ETA].- 3,058,732
VERTICAL OVEN Original Filed July 11, 1956 2 Sheets-Sheet 1 l A l INVENTORS CIMFLE5H.BARNETT-r RICHARD E. TEA 4L5.
nrrarwcrs- Oct. 16, 1962 c. H. BARNETT EI'AI. 3,058,732
VERTICAL OVEN Criginal Filed July 11, 1956 2 Sheets-Sheet 2 I I 1/11 I 11/ 1/ 1 6i BUR/VERS Jig. Z
- IN VEN TOM CH6 171.55 l1. FA RNETT AND BY RICHARD E. TEAGLE 0M,
DAMPER nit seam Patented Oct. 16, 1962 has 3,058,732 VERTICAL OVEN Charles H. Barnett, Shaker Heights, Ohio, and Richard E. Ieagie, North Palm Beach, Fin assignors to The Foundry Equipment (Iornpany, Cleveland, Ohio, a corporation of Ohio Original application July 11, 1956, Ser. No. 597,246, new Patent No. 2,926,897, dated Mar. 1, 1960. Divided and this application Feb. 1, 1960, Ser. No. 6,025
4 Claims. (Cl. 263-8) This invention relates as indicated to a novel vertical conveyor oven, and more particularly to an industrial oven of the general type shown and described in Barnett et al. Patent 1,934,904, for example.
Ovens of the type disclosed in such aforesaid patent have proven very successful in the trade and are now widely used for the baking of foundry cores and the like. A chain conveyor having two parallel vertically disposed courses is loaded with cores at one side of the oven, and such cores are then carried upwardly through a heating Zone and then downwardly through a cooling zone before being unloaded from the opposite side of the oven. Heated air and other gases are forced from a central plenum chamber transversely of such rising course of the conveyor, and these rise to the top of the oven where a portion is drawn oh and the remainder pulled downwardly to the combustion chamber for reheating and recirculation.
In order to increase production, ovens of this general type have been made higher and higher until some of them are now as much as 80 feet high. With this increasing height, certain problems have become accentuated. If the heated air which is forced from the central plenum chamber into the region of the oven through which the ascending course of the conveyor passes must then rise to the top of the oven before being pulled back down to the heating unit, it is found relatively difiicult to do so as the height of the oven increases, and more and more powerful blowers are required. Moreover, once such heated air and gases are thus blown across the ascending course of the conveyor (and the cores transported thereby), such air and gases thereafter merely rise upwardly to the top of the oven without sufficient turbulence to transfer to such cores the amount of heat of which the air and gases are theoretically capable.
In order to increase production, there is a continuing tendency on the part of the oven operators to drive the conveyors at greater speeds and correspondingly to increase the oven temperatures. Possibilities in this direction are, however, severely limited by the fact that the core binders are adversely affected if local temperatures reach too high a level. Thus, in the case of the common linseed oil binder, the cores will become burned if subjected to too high temperatures and in the case of the more recently adopted resin binders, the strength thereof decreases if, once set, they are further subjected to high temperatures. These problems, of course, arise principally with regard to relatively small or thin core portions such as fins and the like which will be fully baked well in advance of the main body of the core. It is essential that these relatively thin and fragile portions of the core should not be overheated during the further baking of the body of the core. Of course, the use of relatively high baking temperatures is also expensive and should be avoided for economic reasons when possible.
The foregoing problems are efiiciently handled in the new and improved Oven structure described and claimed in Barnette et a1. application Serial No. 577,886, Vertical Oven, filed April 12, 1956, now Patent No. 2,926,008, and in certain respects the present invention represents further improvements in the construction disclosed in such application. More particularly, inasmuch as core ovens are required to handle a considerable variety of cores 2 of different sizes, shapes, thicknesses, etc., it is quite important for efficient operation that the oven be capable of adjustment to accommodate itself to the type of core thus handle. Moreover, as the speed of operation is increased, it becomes still more important that such adjustments be relatively precise to ensure proper drying of the cores without overheating or other damage to them.
It is accordingly an important object of our new invention to provide an improved vertical industrial oven capable of adjustment in a very flexible manner to obtain the precise operating conditions desired in each portion of such oven.
Another object is to provide an oven of the type indicated wherein both the extent of the cooling zone and the the temperature of the cooling air may be readily controlled to avoid danger of thermal shock to the cores as they are cooled while nevertheless operating the oven at maximum capacity.
A further object is to provide a simplified duct system for conducting the air and gases to, from, and within the oven to reduce the cost of such installation, to minimize the space required for the same and to ensure proper flow of the air and gases.
Still another object is to provide improved means for disposing of volatiles in the exhaust gases withdrawn from the oven.
Other objects of the invention will appear as the description proceeds.
To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particluarly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.
In said annexed drawing:
FIG. 1 is a vertical elevation of our new industrial oven structure;
FIG. 2 is a vertical section taken on the line 22 on FIG. 1;
FIG. 3 is a vertical section taken on the line 33 on FIG. 2; and
FIG. 4 is a horizontal transverse section taken on the line 4-4 on FIG. 2.
Referring now more particularly to such drawing, the embodiment of our invention there illustrated comprises the usual vertical oven shell 1 insulated in its upper portion and with its lower portion 2 set within a pit 3 so that the level of the adjacent floor 4 will be at the proper elevation for loading and unloading the usual work supporting conveyor trays 5 carried by chain conveyor 6. As shown in FIG. 2, the conveyor loading entrance 7 is at the left and the unloading opening 8 is at the right whereby the ascending trays of the conveyor are loaded as they pass entrance 7 and the descending trays are unloaded as they pass opening 8. The upper end of the conveyor passes about large sprocket wheels 9 and its lower end passes about appropriate guide means.
In the preferred embodiment illustrated, gas burners 10 are located within the combustion chamber 11 internally of the oven directly above the intakes of fans 12 and 13 driven by electric motor 14 located exteriorly of the oven. Such fans define blower means having an outlet extending substantially across the width of a pienurn chamber 15 as illustrated particularly by FIG- URES 3 and 4. In this manner such blower means discharges the heated air and hot gases of combustion upwardly into the vertically extending centrally located plenum chamber 15 which extends to a point adjacent large sprocket Wheels 9 in the upper part of the oven. Damper controlled openings such as 16 in the side ofthe plenum chamber toward the upwardly traveling course of conveyor 6 and similar louvered openings such as 17 in the plenum chamber toward the descending course of such conveyor are adapted to deliver the heated gases transversely of the work supporting trays carried by the conveyor and thus to bake and dry foundry cores or the like on such trays.
As explained more in detail in the cited Patent No. 2,926,008 to Barnett et al., ducts or conduits 18, 19, 20 and 21, preferably of circular or oval cross-section, will be provided passing completely through the plenum chamber and thereby connecting the principal heating side of the oven with recirculation duct 22. Consequently, a considerable portion of the heated gases which are forced from the plenum chamber through the ports 16 first pass across the work supportingrtrays of the conveyor and then again flow back across such trays to such conduits for recirculation through duct 22, combustion chamber 11, blowers 12 and 13, and plenum chamber 15. The cores are, of course, relatively cool at this stage in their processing, and it is desirable to transfer as much heat thereto as quickly as possible by producing turbulence and return flow as above described. A considerable portion of these gases are recirculated to the heater without being required first to flow upwardly to the top of the oven and then to be pulled down to damper regulated recirculation port 23. Consequently, the heated gases which are blown against the work in the upper portions of the conveyor travel are not diluted to an undesirable extent with the gases which have previously been blown against the work in the lower portion of the conveyor travel and which have become partially cooled and saturated.
Inasmuch as the combustion chamber 11 may extend the full Width of the oven, it is capable of heating a large volume fiow of air without undue turbulence. If it is desired to substitute an oil burner for the gas burners, the usual refractory combustion chamber will ordinarily be required.
A stack 24 is provided to carry off a portion of the semi-saturated gases from the top of the oven, and we provide a refractory combustion chamber 25 at the base of such stack with which ducts 26 and 27 communicate. In the form shown, such chamber has a downwardly tapering refractory liner 28 with a gas burner 29 at its bottom providing the heat and air necessary for complete combustion of combustible volatiles in the gases entering through ducts 26 and 27 and passing up the stack. A catalytic combustion unit, commercially available, may be utilized instead, if desired.
Cool air for cooling the cores on the descending course of the conveyor prior to their removal through opening 8 is sucked in through screen S by supply fan 30 and forced downwardly into cooling supply boot 31 which communicates with the side of the oven containing the descending conveyor course through a plurality of damper controlled inlets 32. On each side of supply boot 31 are vertically disposed exhaust ducts 33 and 34 adapted to communicate with the portion of the oven containing the descending course of the conveyor through series of vertically spaced damper controlled outlets 35 and 36 respectively. Suction is applied to such exhaust ducts 33 and 34 by exhaust fans 37 and 38 which deliver to exhaust manifold 39 and stack 40.
In addition to the damper controlled outlet 17 leading from the upper portion of the plenum chamber 15 to the side of the oven containing the descending conveyor course, additional outlet ports 41, 42 and 43 may be provided in the form of conduits extending from the plenum chamber horizontally across recirculation duct 22 in order to deliver heated air and gases across such descending conveyor course in a lower region than such ports 17. These are also damper controlled and when ports 42 and 43 are open (in order to extend the heating 4 zone downwardly), the uppermost ports 32 from cooling air supply boot 31 will normally be closed.
A damper controlled port 44 is also provided leading directly from the side of the oven having the descending conveyor course to supply fan 30 so that the cool air drawn in by such fan through screen S may be tempered as desired to avoid thermal shock due to unduly abrupt cooling of the cores. All three fans 37, 30 and 38 are aligned so that they may be driven by a single motor 45.
It will be seen from the foregoing that we have pro vided a vertical industrial oven of relatively simple and inexpensive construction which nevertheless is much more flexible in operation than ovens previously available for the same purposes. External ducts and platforms previously generally employed have been much reduced or eliminated. The oven as a whole requires considerably less projected floor area and accordingly requires less space within the building. The arrangement of burners 10 above fans 12 and 13 eliminates the need for much duct work previously employed, conserves space and avoids the necessity of a heavy refractory lined combustion chamber. The work is afforded a longer elfective travel through the heating zone since the plenum chamber 15 begins relatively close to loading opening 7 (there being no combustion chamber below fans 12 and 13). The relative extents of the heating and cooling zones on the descending side of the oven may also be regulated through wide limits and the cooling action may be tempered in a manner to avoid danger of thermal shock to the work.
This application is a division of our prior application Vertical Conveyor Oven, Serial No. 597,246, filed July 11, 1956, now Patent No. 2,926,897.
Other forms embodying the features ofthe invention may be employed, change being made as regards the features herein disclosed, provided those stated by any of the following claims or the equivalent of such features be employed.
We therefore particularly point out and distinctly claim as our invention:
1. In a vertical oven having a vertically disposed end less conveyor, a 'plenum chamber stationed between courses of said endless conveyor to define a heating zone, blower means directly and vertically beneath said plenum chamber having an outlet extending substantially across the width of the chamber operative to blow gases vertically upwardly and into said chamber, said oven having a loading opening for one of said courses at a level immediately below said blower means, burner means extending across substantially. the entire width of the oven above the blower means and in direct communication with the air intake of the blower means to afiord an increased area for the installation of such blower means thereby to increase the capacity of the oven, and ports in said plenum chamber to deliver heated gases therefrom into a work-containing region of said oven.
2. In a vertical oven having an endless conveyor with parallel vertical courses, a plenum chamber between said courses defining a heating zone, ablower directly and vertically beneath said plenum chamber having an outlet extending substantially across the widthof the chamber operative to blow gases. vertically upwardly and directly into saidrchamber, said oven having a loading opening for one course of said conveyor at a level immediately below said blower, heating means also above said blower in direct communication with the intake thereof to place such plenum chamber relatively close to such loading opening and provide effectively a longer travel through such heating zone, said heating means extending substantially across the width of said oven to heat a relatively large volume flow of air, and ports in said plenum chamber to deliver heated gases therefrom to a work-containing region of said oven.
3. In a vertical oven for baking cores and the like having an endless conveyor with parallel vertical courses, one ascending and one descending, a vertically disposed generally central plenum chamber between said courses defining a heating zone, a vertically disposed recirculation duct also between said courses and generally paralleling the plenum chamber, a plurality of blowing means to provide increased blowing capacity, said blowing means being substantially coaxially spaced across the width of said chamber and spaced vertically beneath said plenum chamber to define an outlet also extending substantially across the width of the chamber and operative to blow gases vertically upwardly and directly into said chamber, said oven having a loading opening for the ascending course of said conveyor at a level immediately below said blower, heating means stationed within the recirculating duct and above and in communication with the air intake of said blowing means so that the heating and blowing means are serially related in the path of such intake and the recirculating air reaches the heating means prior to reaching the blower means, such structural arrangement placing said plenum chamber relatively close to the loading opening to provide effectively a longer travel through such heating zone, said heating means extending substantially across the entire width of said oven substantially parallel to said chamber to provide increased heating 25 capacity without undue turbulence, and ports in said plenum chamber to deliver heated gases therefrom to the work-containing region of said oven.
4. In a vertical oven for baking cores and the like having an endless conveyor with parallel vertical courses, one ascending and one descending, a generally central plenum chamber between said courses defining a heating zone, a vertically disposed recirculation duct also between said courses, blower means stationed directly and vertically beneath said plenum chamber and spaced widthwise thereacross to define an outlet therefor also extending substantially across the chamber and operative to blow gases vertically upwardly and directly into said chamber, said oven having a loading opening for the ascending course of said conveyor at a level immediately below said blower, heating means stationed within the recirculation duct and also above said blower in connection with the air intake thereof to place such plenum chamber relatively close to such loading opening, thereby providing efiectively a longer travel through such heating zone, said heating means extending substantially across the width of said oven substantially parallel to said chamber, and ports in said plenum chamber to deliver heated gases therefrom to a work-containing region of said oven.
References Cited in the file of this patent UNITED STATES PATENTS 2,110,352 Baker Mar. 8, 1938 2,525,661 Fox Oct. 10, 1950 2,628,087 Mayer Feb. 10, 1953