US2653392A - Foundry drying oven - Google Patents

Description

p 9, 1953 E. w. VON HOFEN ET AL 2,653,392

FOUNDRY DRYING OVEN Filed June 11, 1951 3 Sheets-Sheet l E 0/5.): F|E.l a

Inventors: 54a Wm HOPE/V and f ew E. WH/TNE),

Sept. 29, 1953 E. w. VON HOFEN ET AL 2,653,392

FOUNDRY DRYING OVEN Filed June 11, 1951 3 Sheets-Sheet 2 IE- [WIN/W5. 5424 W raw/6mm. am flaw E. WH/TNE Sept. 29, 1953 E. w. VON HOFEN ET AL FOUNDRY DRYING OVEN 3 Sheets-Sheet 3 Filed June 11 1951 N WEE: Q

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Patented Sept. 29, 1953 FOUNDRY DRYING OVEN Earl W. von Hofen, Pittsburgh, Pa., and Fred R. Whitney, Lorain, Ohio, assignors to United States Steel Corporation, a corporation of New Jersey Application June 11, 1951, Serial No. 230,982

This invention relates to a drying oven for foundries and, in particular, to an oven adapted for drying the molds and cores used in pouring massive castings such as the large ingot molds used by the steelindustry in considerable numhere.

In pouring ingot molds, a metal flask having the mold pattern therein is rammed with moist sand, the pattern is withdrawn and the resulting layer of sand in the flask is dried. Similarly, a core corresponding in size and shape to the desired ingot, is made by ramming sand in a core box having an arbor therein, stripping the box and drying the layer of sand thus produced on the exterior of the arbor. Heretofore, the flasks and cores have been dried by firing heating flames thereon with rin and line burners. The flames had contact almost exclusively with the exterior of the flasks and cores and this made the drying of the flasks very slow, since it was necessary for the heat to penetrate the flask wall before driving moisture out of the sand layer.

We have invented a novel drying oven specially suited for the flasks and cores used in pouring ingot molds, which overcomes the aforementioned objection and permits quicker and more efficient drying of the flasks particularly, but is also of advantage in effecting proper circulation of heated air about the cores. In a preferred embodiment, we provide an oven open at the top, having a floor, side and end walls, and a removable cover. Supply and exhaust flues for heated air are formed in one side wall. The cover has spaced upper and lower walls defining plenum chambers each communicating at one end with the supply flue and at points spaced therealong, with the interior of the oven. Exhaust passages beneath the floor communicate with the interior of the oven and the exhaust flue. Preferably we arrange a flask-drying oven and a core-drying oven side-by-side. The two ovens are generally similar, except for the type of floor, that of the flask-drying oven having large openings spaced thereover, in registry with which the flasks are spotted, and that of the core-drying oven being a grating. Each oven has its own source of heated air and a blower for repeatedly recirculating air from the oven to the heater and back to the oven. Cross-connection flues between 9 Claims. (01. S i -104) Figure l is a plan view of a flask-drying oven and a core-drying oven with the covers removed and the floors partly broken away;

Figures 2 and 3 are cross-sections taken alon the planes of lines II--II and III III, respec tively, of Figure 1 showing the covers in place;

Figures 4 and 5 are longitudinal sections taken along the planes of lines IV--IV and V- -V, respectively, of Figure 1 showing the covers in place;

Figure 6' is a plan view of one of the covers;

Figure 7 is a longitudinal section therethrough taken along the plane of line VIIVII of Figure 6; and

Figure 8 is a cross-section through the cover portion taken along the plane of line VIIIVIII of Figure '7.

Referring now in detail to the drawings, we preferably arrange a flask-drying oven it and a core-drying oven H side-by-side. The ovens are identical in construction except for the character of the floor (as will be specifically pointed out later) though they differ slightly in certain dimensions, so a description of the flask-drying oven will suflice for both, corresponding parts of the core-drying oven being designated by the same reference numerals rimed. Oven It is defined by side walls is and i3, end walls it and i5 and a floor I6. Wall I3 is common to both ovens and walls It and it are continuations of walls it and 15. Wall l2 has upper and lower flues ll and 48 therein defined by top slabs Ell and intermediate slabs til (see Figures 2 and t) Floor It is composed of pallets or slabs is laid on spaced piers 26 extending across the oven foundation 2%. Each pallet is has a central opening 25 therein. The piers 28 define exhaust passages 22 below the floor and ports 23 in the inner side of wall I2 provide communication between the passages and flue I8.

The oven has removable covers 24 thereon spanning the distance between walls I2 and [3. For convenience in handling, the covers preferably have a width only about double that of passages 22, thus requiring three covers for the full length of the oven. As shown in Figures 6 through 8, each cover 24 is fabricated from structural members and plate and has a peripheral depending flange or vertical wall 25. Bottom plates 26 secured to the covers, together with the flange and intermediate structural members, define spaced plenum chambers 27. The interior of covers 24, except for the bottom plate 26, is lined with thermal insulation. Plates 26 have openings 28 adjacent the outer ends of the cover adapted to register with ports 29 extending through the top of spaced slabs I! overlying flue ll. Each port has a control damper therein. Plates 26 also have holes 3! Spa d therealong alined with openings 2! in pallets [9.

An air heater 32 of any suitable type is mounted adjacent one end of wall i2 and has its outlet connected by a pipe 33 to flue IT. A blower 34 adjacent the heater has its inlet connected by a pipe 35 to an uptake 35 (see Figure 4) communicating with flue It. The blower delivers air through a pipe 3? to the inlet of the heater. Flues i? and 28 thus serve as supply and return mains, respectively. By this arrangement, it will be apparent that air from the heater flows through pipe 33, flue it, and ports 29 into chambers 2? in covers 2t. Air is discharged from these chambers through ports 3! into the oven and downwardly through the interior of flasks 38 standing on floor IS in registry with openings 2!. The heated air thus has direct contact with the sand layer lining the flasks and quickly absorbs moisture therefrom. Aiter passing through the flasks, the air flows through openings 2|, passages 22 and ports 23 to flue l8 whence it returns to the blower by uptake .35 and pipe 35 and finally to the heater by pipe 3'2. In order to eliminate moisture from the circulating air, a portion thereof may be continuously vented to the atmosphere and replaced by fresh air. Dampers til permit the distribution of heated air to be controlled longitudinally of the oven and ports 35 are graduated in size to effect substantially uniform distribution transversely of the oven.

Core-drying oven 5 i operates in the same manner as the flask-drying oven. Its construction is similar except that its floor is composed of grating panels 39. Cores 49 may thus be stood anywhere on the floor with the assurance that they will be subjected to the drying effect of heated air flowing downwardly from ports 3|, around the exterior of the cores and through the voids in the grating into passages 22.

It may be desirable at times to divide the air from either heater between the two ovens or to deliver air from both heaters to one oven. To permit this, we provide cross-connecting supply and return flues H and 42 (see Figure 3) in walls i l and i4. Flue l! connects flues l1 and H while flue 42 connects flues I8 and I8. A damper t3 normally closes both flues ll and 42 but it may be opened to permit flow of heated air therethrough from the heater of either oven to the other. Dampers 44 and 44' in flues l1, l8 and ll, 53' are normally open but permit the output of from one or both heaters to be divided as desired between the two ovens.

It will be apparent from the foregoing that our invention has many advantages. In the first place, drying of the flasks is efiected more efflciently than heretofore since the heated air has direct contact with the sand lining and little or no heat is wasted in the metal wall of the flasks. Secondly, the time required for adequate drying is reduced since the sand lining the flasks dries from its inner surface outwardly instead of the reverse. In addition, the oven may be easily loaded and emptied by a crane which also serves for removing and replacing the covers. Exact spotting of the cores is not necessary and there is considerable leeway in respect to positioning the flasks so as to insure that air will flow through the interior thereof. The construction of the ovens is simple and long-lasting, requiring but little maintenance. Recirculation of heated air repeatedly between the oven and heater reduces the fuel consumption as compared with heating a continuous supply of fresh air or applying heat ing flames directly to the flasks and cores.

Although we have disclosed herein the preferred embodiment of our invention, we intend to cover as well any change or modification therein which may be made Without departing from the spirit and scope of the invention.

We claim:

1. A drying oven comprising side and end walls, a floor and a removable cover spanning said side walls, said cover including a layer of thermal insulation and a bottom spaced therebelow, vertically spaced warm-air supply and return flues extending along one of said side walls, ports spaced along the top of the upper flue, openings in said bottom registering with said ports, said bottom and floor having inlet and outlet ports distributed thereover, respectively, and transverse exhaust passages below said floor communicating with the lower flue.

2. A drying oven as defined by claim 1 characterized by dampers in said first-mentioned ports.

3. A drying oven comprising side and end walls, a floor and a removable cover spanning said side walls, said cover having a top and bottom spaced apart defining a plenum chamber, said bottom having ports therein communicating with the interior of the oven, said floor having exhaust ports therein, and means supplying hot gases to the plenum chamber and withdrawing them through said exhaust ports, said means including upper and lower supply and exhaust flues in one of said side walls, said supply flue communicating with said chamber along one side thereof, and transverse passages below said floor connecting the exhaust ports to said exhaust flue.

4. A drying oven as defined by claim 3 characterized by dampers controlling the flow of gases from said supply flue to said chamber.

5. A drying oven as defined by claim 3 characterized by said floor being solid for the most part and said exhaust ports being spaced apart and adapted to register individually with bottomless hollow molds standing on the floor.

6. A drying oven as defined by claim 3 characterized by said floor being a grating adapted for circulating gases around the exterior of cores spotted thereon in spaced relation.

'7. A drying oven comprising a floor, side and end walls and a removable cover spanning said side walls, air-supply passages in said cover and return passages below said floor extending across the oven and communicating therewith, supply and return mains at one side of the oven communicating, respectively, with said supply and return passages, and air-heating and circulating means connected to said mains, said mains being flues in one of said side Walls.

8. -A drying oven comprising a floor, side and end walls and a removable cover spanning said side walls, air-supply passages in said cover and return passages below said floor extending across the oven and communicating therewith, supply and return mains at one side of the oven communicating, respectively, with said supply and return passages, and air-heating and circulating means connected to said mains, said supply main having ports spaced therea-long discharging into the passages in the cover, respectively.

9. A drying oven comprising a floor, side and end walls and a removable cover spanning said side walls, air-supply passages in said cover and return passages below said floor extending across.

5 6 the oven and communicating therewith, supply Number Name Date and return mains at one side of the oven com- 1,525,131 Hitchcock Feb. 3, 1925 municating, respectively, with said supply and re- 1,620,289 Ridley Mar 8, 1927 turn passages, and air-heating and circulating 1,737,259 Miller Nov. 26, 1929 means connected to said mains, said return mains 5 1,827,194 Grothe Oct. 13, 1931 having ports spaced therealong communicating 2,161,162 Harsch June 6, 1939 with said return passages, respectively. 2,376,174 Munning et a1 May 15, 1945 EARL W. VON HOFEN. 2,471,964 Kisskalt May 31, 1949 FRED R. WHITNEY. 10 FOREIGN PATENTS Number Country Date References Cited in the file of thls patent 844,901 France Mary 1, 1939 UNITED STATES PATENTS Number Name Date 965,366 Bradley July 26, 1910 15

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