US2926897A

US2926897A - Vertical conveyor oven

Info

Publication number: US2926897A
Application number: US597246A
Authority: US
Inventors: Charles H Barnett; Richard E Teagle
Original assignee: Foundry Equipment Co
Current assignee: Foundry Equipment Co
Priority date: 1956-07-11
Filing date: 1956-07-11
Publication date: 1960-03-01
Anticipated expiration: 1977-03-01

Description

March 1, 1960 c. HBARNETT ETAL VERTICAL coNvEYoR OVENl 2 sheets-shet 1 Filed July ll, 1956 .n MT mm ma. w n w K zA J# nllnuu f/ J A2 RICHARD E. 7 A GLE. by

Jig.

March 1, 1960 c. H. BARNETT ET AL 2,926,897

. VERTICAL coNvEYoR ovEN Filed July 11, 1956 Sheets-Sheet 2 IN1/mfom CHA L55 h'. ZAR/V577 Mo ABY k/cf/ano f. 725461.15 m24 IOL/w/ ATTORNEYS.

i 2,926,897 vElmcAL coNvEYoR ovnN Charles H. Barnett, Shaker Heights, and Richard E. Teagle, Parma, Ohio, assignors to 'lfhe Foundry Equipf ment Company, Cleveland, Ohio, a corporation of Ohio Application July `11, 1956, serial No'. 591,246

9 claims. r (ci. zes-s) This invention relates as indicated toa 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. r

Ovens of the type disclosed in such aforesaid patent have proven very successful inthe 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 even, 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 off `and the remainder pulled downwardly to the combustion chamber for reheating and recirculation. 7

` In order to increase type have been madehigher 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 thecentral plenum chamber into the region fof the oven through` which the ascending course of the conveyor passes must then rise to the top of the oven heating unit, it is found relatively dilcult to do so aS the height ofthe oven increases, andinore 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 lsuilicient turbulence totransfer to `such coresfthe amount of heat of which the` air and gases are theoretically/capable In order to increase production, thee is a continuing tendency on the part of'theoven 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 higha level. Thus, in the case of the common linseed `oil binder, the cores will ,n become bumed if subjectedto too high temperatures and in the case of the more recently adopted resin binders,A the strength thereof decreases if, once,set,lthey`are` further subjected to" high temperatures.` These problems, of course, arise principally with regard torelatively small or thin core portions such` as fins andthe like which will be fully bakedwell in the `advance `of the main body of the core. Y lt is essentialthatthese relatively thin and fragile por- `tions `of the core `should not .be overheated during the 10 i e over, as the speed of operation is increased, it becomes production, ovens of this general' before being pulled back down to the 2,926,897 Patented Mar. 1, 1960 new and improved oven structure describedand claimed in Barnett et al. application Serial No. 577,886, Vertical Oven, led April 12, 1956, and in certain respects the present invention represents further improvements inthe construction disclosed in such application. More particui larly, inasmuch as core ovens are required to handle a considerable variety of cores of different sizes, shapes, thicknesses, etc., it is quite important for ecient operation that the oven be capable of adjustment toaccommodate itself to the type of core thus handled. Morestill more important that such adjustments be relatively precise to ensure proper drying of the cores without of but a few of the various ways in which'the overheating or other damage to them.

Itis accordingly an important object of oui new invention to provide an improved vertical industrial oven capable of adjustment ina very llexible manner to obtain the precise operating conditions desired in each portion of such oven. i

Another object is to provide an oven of the type indicated wherein both the extent of` the cooling zone and the temperature of the cooling air may be readilycon-` trolled to avoid danger of thermal shock to the cores as they are cooled while nevertheless operating the oven at maximum capacity.

A further object s to provide a simplified duct system for conducting the air and gases to, from, and within the oven toreduce the cost of such installations, to minimize the space required for the same and to ensure proper flow of the air and gases.

Still another object is to disposing of volatiles in from the oven. e e

Other objects of the invention will appear as e the description proceeds.

` To the accomplishment of the foregoing and `related ends, said invention thencomprises the features hereinafter fully described and particularly pointed out in the provide improved means for the exhaust gases withdrawn i claims, the following description and `the ,annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, r 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 2-2 on Fig. 1;

Fig. 3 is a vertical section taken on .the line 3 3 on Fig. 2; and l Y 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 iloor 4 will be atthe proper elevation for loading and unloading the usual work supporting conveyor trays 5 carried 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 passwopening 8. The upper end of the conveyor passes about large sprocket wheels 9 and its lower end passes about appropriateguide means.

further baking ofthefbody of the` core. Of course, the,

use of `relatively-,high bakingternperatures is also expen* sive andshould be avoided `foreconomic reasons when possible.

l .a The zforegoing problems' are fnetliciently handled in the combustion upwardly into In the preferred embodiment illustrated, gas burners 10 by chain conveyor 6.

are located within the combustion chamber 11 internal` trallly 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 of the-plenum chamber toward the upwardly traveling'course of conveyor 6 and similar louvered openings Ysuch l as 17 in the plenum chamber toward the descending course of such conveyor are adapted to deliver the heated gasestransversely of the work supporting trays carried by the conveyor and thus to bake and dry foundry cores or the like on such trays. s

l As explained more in detail in Barnett et al., appiication Serial No. 577,886, ducts o-r conduits l, 19, 26 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 222. Consequently', a considerable portion of the heated gases which are forced from the plenum chamber through the ports 16 iirst pass across the work supporting trays of the conveyor and then again HOW back across such trays to suchV 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 tlow as above described. A considerable portion of these gases are recirculated to the heater without being required first to vflow upwardly to the top of the ovenand then to be pulled down to damper regulated recirculation port 23.. Consequently, the heated gasesV which are blown against the work in the upper portions ofthe conveyor travel are not diluted to an undesirable extent with the gases which haveV 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 iiow of air without undue turbulence. lf it is desired to substitute an oil burner for the gas burners,`the. usual refractory combustion chamber will lordinarily 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 26v and 27 communicate. in the form shown, such chamber has a downwardly tapering refractory lincrwith a gas. burner 29 at its bottom providing the heat and air necessary for cornplete combustion of combustible volatilesin 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 *he cores on the descending. course of the conveyor prior to their removal through opening 8 is sucked in through screen S by supply fan 39 and forced downwardly into cooling supply bootv 31 whichy communicates with the side of the oven containing the descending conveyor course through a plurality of damper controlled inlets 32. On' each side ofsupply boot 3i are 'vertically disposed exhaust ducts 3 3, and, 3.4 adapted to communicate with.l the p ortion of the o ven containing tbe. descendvingpcourse of the conveyor through series of vertically spacedldamper controlled

outlets

35 and 36 respectively. @Suction isv applied to

such exhaust ducts

33 and 34 by

exhaust fans

37 and 38, which deliver'to xhaust manif old 39 and stack 40.

In additiontto the damper. controlled outlet 17 leading from the upper portion. of theplenum chamber 15 to te. Sido.. 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- .22,1n order todeliverheatednir and gases across such; dessendnnconvoan course; in. a. lowerregienf, than, sneu,

:ports 17. These are also damper controlled and when '

ports

42 and 43 are open (in order to extend the heating 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 ofthe 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, 3o and 3S are aligned so that they may be driven by a single motor 45.

It will be seen from the foregoing that we have provided 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 purpose. External ducts and platforms previously generally employed have been much reduced or eliminated. The'oven as a whole requires considerably less projected oor area andv accordingly requires lessv space within the building. The arrangement of burners 10 above

fans

12 and 13 eliminates the needfor much duct work previously employed, conserves space and avoids the necessity of a heavy refractory lined cornbustion chamber. The work is afforded a longer effective 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 heatingand cooling. zones on the. descending side ofthe oven may also vbe regulated through wide limits andthe cooling action may be tempered in a manner to avoid danger ofy thermal'. shock to the work.

Other modes of applying-the principle of the invert-Q l tion may beemployed, change being made as regards the details described, provided the features stated in any'A of the following claims or the equivalent of such'be employed.

We therefore particularly pointout and distinctly claim as our invention: 1.*In a verticaloven for baking cores and the like4 having an endless conveyor with parallel vertical courses, one ascending and vone descending, a generally central plenum chamber between said courses, heating and blow ing means forrsupplying heated gases under pressure to. said plenum chamber, ports in said plenum chamber toward said ascending. conveyor course toafford heated gas iow therefrom transversely of said course, a. recirculating duct. adjacent the lower portion of said plenum chamber on the side toward said descendingcourse adapt.`

ed to receive a portion of the gases from such side of' said oven for delivery to said heating' and" blowingmeans',A`

and a plurality ot' conduits extending transversely through said plenum. chamber from the side ltoward' said" ascending course to said recirculating duct;` a plurality of conduits extending from said plenum chamber transversely of said recirculating duct to the region of sai'dV oven containing said descending conveyor course.

2. In a vertical oven for baking cores and the like v having an endless conveyor with parallel vertical courses, one. ascending and one descending, a generally central plenum chamber between said courses,.ablower"directly'A beneath said plenum. chamber operative to b'lovI` gasesj upwardly into said: chamber, heating meansA laterally of said' chamber'and closely above said' blower in communication with theintake thereof, a vertically extending`- recirculating duct adjacent the lowerportion' of said cham--v ber4 on the side' toward saidl descendingL course Yad'apted Y to receive a portion of" the gases from such region ottlfie' oven and conductv themA downwardlyY to said heater andt blower, ports' in saidI plenum chamber towardl said'f ascendingI conveyor coursey to; aord'heatedgas' dow there-y from` transversely of'said course, a plurality' of conduits' extendingr transversely through said plenum clvlamtxer from the side toward said ascending course to said re-- circulating; duct, a: pluralityof conduits-:extendingfrom said plenum chamber transversely of said recirculating duct to the region of said oven containing said descending conveyor course, a laterally oiset stack communieating with the upper end of the oven adapted to draw oit a portion of the gases therefrom, means in the bot- `tom of said stack for oxidizing combustible volatiles contained in such gases, a cooling air supply boot extending downwardly along the side of the oven generally opposite to said recirculating duct on the other side of said descending conveyor course, ports for admitting cooling air from'said boot to said oven, exhaust ducts directly on each side of said boot communicating with said oven, an exhaust manifold above said boot with which said exhaust ducts communicate, a supply fan for said hoot, an exhaust fan for each said exhaust duct aligned with said supply fan, common drive means for all three said fans, and a passage from the upper region of said oven to the intake of said supply fan for admitting heated gases thereto to temper the cooling air.

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 generally central plenum chamber between said courses, a blower directly beneath said plenum chamber operative to blow gases upwardly into said chamber, heating means also above said blower in communication with the intake thereof, a vertically extending recirculating duct adjacent the lower portion of said chamber on the side toward said descending course adapted to receive a portion of the gases from such region of the oven and conduct them downwardly to ysaid heating means and blower, ports in said plenum chamber toward said ascending conveyor course, ports in the upper portion of said plenum chamber toward said descending conveyor course, a conduit extending from said plenum chamber transversely of said reirculating duct to the region of said oven containing said descending conveyor course, a cooling air supply b oot extending downwardly along the side 'ofthe oven generally opposite to said recirculating duct pn the other side of said descending conveyor course, pprts for admitting cooling air froI y said b oot to said Aoven, ex, haust ducts directly on each side yof said boot communieating, with said oven,` and damper means arranged to regulate said ports and conduits to modify the work heating and cooling zones within said oven.

4. In a vertical oven for bakingrcores and the like having an endless conveyor with parallel vertical courses, one ascending and one descending, a generally central plenum chamber between said courses, damper controlled ports in said chamber opening toward said ascending course and also toward said descending course, a blower communicating with the lower end of said chamber, a vertically extending recirculating duct adjacent the lower portion of said chamber on the side toward said descending course adapted to receive a portion of the gases from the latter region of said oven and conduct them downwardly to said blower, heating means in advance of said blower operative to heat such gases from said duct, and conduits from said chamber passing transversely through said duct and opening toward said descending conveyor course.

5. The oven of claim 4 also including conduits extending through vsaid chamber from the region of said oven containing said ascending conveyor course to said recirculating duct.

6. The oven of claim 4 also including a cool air supply boot opening into said oven on the opposite side of said descending conveyor course to said conduits.

7. The oven of claim 4 also including a cool air supply boot opening into said oven on the opposite side of said descending conveyor course to said conduits, and a duct leading from the upper region of the oven to cool air supply means for said boot to temper the air supplied through said boot.

8. 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, ports in said chamber opening toward said ascending and descending courses, a vertically extending recirculating duct adjacent the lower portion of said chamber on the side toward said descending course adapted to receive a portion of gases from the latter region of said oven and conduct such gases downwardly and into said plenum chamber, conduits from said chamber passing transversely through said duct and opening toward said descending conveyor course, and means to advance heated gases through said plenum chamber and out said ports and transverse conduits.

9. The oven of claim 8 also including conduits extending Vthrough said chamber from the region of said oven containing saidascending conveyor course to said recirculatingduct. L i

References Cited in the le of this patent UNITED STATES PATENTS l1,914,567 Hopkins et al. -..June 20, 1933 2,110,352 Baker Mar. 8, 1938 2,257,180 Mayer Sept. 30, 1941 2,525,661 Fox Oct. 10, 1950 2,558,338 Clements June 26, 1951 2,603,882 Mayer July 22, 1952 2,628,087 Mayer Feb. 10, 1953 2,658,742 Suter et al. Nov. 10, 1953 2,769,504 Miller Nov. 6, 1956