US1891981A - Heat treating oven - Google Patents

Description

1932. c. A. HERBST I HEAT TREATING OVEN Filed Feb. 18, 1951 ZZZ/67215;! aareizce Qflerbsi Patented Dec. 27, 1932 UNITED STATES PATENT OFFICE CLARENCE A. HERBST, OF CHICAGO, ILLINOIS, .ASSIGNOR TO ECONOMY FUSE AND MAN I FACTUBING 00., OF CHICAGO, ILLINOIS, .A CORPORATION OF NEW YORK HEAT TREATING OVEN Application filed February 18, 1931.

This invention relates to improvements in a heat-treating oven which is especially applicable for heat treating cold-molded products.

It is an object of the invention to provide an oven which may be heated by combustion, such as by gas burners and into which material may be charged on trays and racks and to provide means for circulating the heated air within the oven and to so design the apparatus that substantially uniform tempera ture conditions may be maintained for all the material being heat-treated.

It is further an object of the invention to provide a series of radiator tubes on each side of the oven which is separated from the trays and racks of material by heat-radiating shields and to use a fan at one end of the oven which produces a circulation of the air so as to draw the air past the material being treated and direct the air to flow between the walls of the oven and the shields thereby passing over the radiator tubes and to additionally provide for uniform temperature conditions throughout the length of the oven by admitting a portion or portions of the heated air from the space between the shields and the walls to the interior of the oven in contact with the material treated while the remainder of heated air passes to the extreme end of the oven.

Further objects and advantages of the invention will be more readily apparent from the description taken in connection with the attached drawing, in which Figure 1 is a horizontal section taken through the oven illustrating the racks and trays diagrammatically;

FigureQ is a vertical longitudinal section of the oven taken on the plane indicated 22 in Figure 1, and

Figure 3 is a vertical transverse section of the oven showing the burners and flue connections.

Serial No. 516,666.

in the usual manner such as bymagnesia I opposite end of the oven protrudes thereinto and carries a circulating fan 13 while the shaft is driven by an exterior pulley 14. A

plurality of racks 15, which carry a plurality of: trays, for the material treated may be charged into the oven as indicated in Figures 1 and 3 where there are shown four racks extending throughout the length of the oven. Heat radiating shields 1616 extend from top to bottom of the oven but the ends thereof are spaced from the ends ofthe oven. A closed combustion chamber 17 is provided at each side of thebottom of the oven into which extend a pair of burner tubes 1818. The gases burned in the combustion chambers are directed to flow through a series of radiator tubes 19 which extend vertically between the lower combustion chambers and a pair of closed headers 2020 at the upper portion of the oven. The consumed gases are directed through flues 21-21 to a stack 22.

It will, therefore, be understood that all the air within the oven which comes in contact with the material treated is heated by radiation from the radiator tubes. The fan 13 is driven in such direction that the air within the oven is drawn from the end of the oven which carries the doors towards the fan, and the air which passes the fan is directed laterally to flow forward towards the doors of the oven in the conduits formed be tween the walls and the shields thereby coming in contact with the heated radiator tubes. The arrows in Figure 1 illustrate the flow of air.

An oven of the type disclosed herein is especially adaptable for use in heat-treating cold-molded products. Such products are molded to the proper shape and the-n charged into the oven and heat is applied with a gradually rising temperature for a period of several hours, during which the cold-molded products are absorbing heat. lVhen the critical temperature is reached, a reaction occurs and the material is transformed into ahard and infusible product. During the reaction heat is being given out from the material since the reaction is exothermic. highly desirable that all of the material be brought to the critical temperature at substantially the same time.

It will be obvious that if asingle fan is used to draw the air from one end of the oven to the other end and then pass over the radiatortubes back to the first end of the oven that the last rack, which is charged into the oven, will be subjected to' a greater tempera;

ture than the first rack which is closest to the fan since the temperature will diminish towards the fan, due to the absorption of heat. It is, therefore, necessary to add additional heat units at successive points along the oven so that the material which is nearest the fan will receive the same amount of heatas the material nearest the doors. 1

One manner of obtaining this desirable result is illustrated in .Figure 1 in which I have showna pair of bafiies 23-23 adjacent openings 2al24 in the shields at the middle portion of the oven. The battles are so arranged that a portion of the air flowing towards the front endof the oven is caused to flow hrough the openings 24 and join the current of air flowing towards the fan. The additional air which flows through the openings will provide sufiicient heat units to maintain a more uniform temperature at the opposite ends of the oven.

It is also desirable to have the combustion chamber insulated at the bottom of the oven, such as by insulating material, indicated 25 in Figure 3, so that the lower trays of material will not receive a greater proportion of heat than the uppertrays due to direct radiation from the combustion chamber through the shields. e

My invention is particularly adapted to be -used in connection with an oven in which the dimension in the'direction of the current of circulating air is substantially greater than the dimension across the current of air, but various changes and modifications may be resorted to without departing from the spirit of the invention as expressed in the appended claims. The important feature of the invention is that in an oven of the type mentioned, I provide for uniform temperature conditions throughout the oven by the design of the radiating shields and openings at certain-points of the oven to compensate for the heat absorbed by the first material which the air passes over.

It is, therefore,

shieldsto compensate for the absorption of heatby the-material treated. v y

2. A heat treating oven comprising a closed. chamber, a pair of conduits for the circulation of air on the opposite sides of the chamber, means for'dirculating the air within the chamber by drawing the air from one end of the chamber to the other between the side conduits during which the air passes over the material treated and then forcing the air to flow longitudinally in the opposite direction through said conduits, means for heating the air as it flows through the side conduits and means for admitting portions of the heated air from the conduits into the space therebetween at points intermediate the ends of the oven. I

i v A. heat treating oven comprising a closed chamber, a pair of heat radiating shields at the sidesof the chamber spaced from the walls to define circulating conduits for the air within the chamber, a fan within the chamber at one end thereof operative to draw the air towardsthe fan from the opposite-end of the chamber between the shields and todirect theair to flow'back towards the opposite end of the oven by flowing through Us thecirculating conduits and means for heating the air as it flows through the circulating conduits. said conduits having openings at points intermediate the ends of the chamber whereby some of the air is drawn into the central portion of the chamber before it reaches the end of the chamber toward which it is flowing.

4. A heat treating oven comprising a closed chamber having side and end walls, a pair of longitudinal combustion chambers along'the sides of the chamber adjacent the bottom thereof, a pair of longitudinal headers at the upper portion'of the oven, radiator tubes joining the combustion chambers 3 to the headers, a pair'of heat radiating shields within the chamber on the inner side of the radiator tubes. means for circulating the air in the chamber by drawing the air towards the end of the chamber between the shields and directing the air to flow back towards the first end ofthechamber in contact [with the radiator tubes, said shields having openings intermediate the ends of the chamber andbafl'les adjacent said openings for directing some of the air back to the central portion of the chamber before it reaches the end of the chamber toward which it is flow A heat-treating oven comprising a closed air chamber having a doorway at one end thereof, racks for the material to be heattreated adapted to be moved into said chamber through said doorway, means for closing said doorway, a pair of air circulating passageways extending along the opposite sides of the chamber within the interior thereof open at their ends for communication through the central portion of the chamber, an air circulating fan centrally positioned adjacent the end of the chamber opposite the doorway, said fan being adapted to draw the air longitudinally of the chamber past the material to be heat-treated and to force the air to flow longitudinally in the opposite direction through said passageways, means for heating the air substantially throughout the entire length of said passageways as the air fiows therethrough, the inner walls of said passageways having vertical slotted openings extending substantially throughout the entire height thereof, placing the passageways in communication with the central portion of the chamber at points intermediate the ends of the chamber and vertical bafiles extending from the edges of said slots farthest from the fan and directed inwardly with respect to said air passageways whereby predetermined portions of air flowing through said passageways are caused to be directed into the central portion of said chamber to maintain a more even temperature condition of the air flowing past the material to be heat-treated.

6. A heat-treating oven comprising a closed air chamber having a length materially greater than the width thereof, a doorway at one end of said chamber, a plurality of racks for supporting the material to be heat-treated adapted to be moved into said chamber through said doorway and to remain station ary within said chamber while the material is being heat-treated, means for closing said doorway, apair of air circulating passageways extending along the inner side walls of said chamber substantially throughout the entire length thereof, said passageways being open at their opposite ends for communication through the central portion of said chamber adjacent the ends thereof, an air circulating fan centrally positioned adjacent the end of said chamber opposite said doorway adapted to draw the air longitudinally of said chamber past the material to be heattreated and to direct the air to flow longitudinally in the opposite direction through said passageways along the side of said chamber, means for progressively heating the air as it flows through each of said passageways substantially throughout the entire length thereof, the inner walls of said passageways havof air flowing

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