US2023101A - Furnace - Google Patents

Description

Dec. 3, 1935..

w. ROTH El AL FURNAC E 2 Shecs-Sheet 1 Filed July 10, 1934 INVENTORS- WITNESSES -ATTO'RNEY Patented Dec. 3, 1935 pairs STTES rATENT QFFIQE FURNACE Application July 10, 1934, Serial No. 734,468

15 Claims.

Our invention relates to furnaces and particularly to cooling means therefor.

An object of our invention is to provide a relatively simple and efiicient means for circulating air or other gases in a closed annealing furnace structure to cool the charge.

Another object of our invention is to provide means for quickly cooling the charge in a closed furnace structure without the admission of air into the same.

Another object of our invention is to provide means for moving the air or gas in a furnace structure in either one of two different paths during the operating cycle of the furnace.

Other objects of our invention will either be pointed out specifically hereinafter or willbe evident from a description of the device and of its operation.

In practicing our invention we provide a furnace structure with a double-wall outer shell having an air space therein, a movable cover or closure member for the otherwise open end of the furnace chamber and a fan supported by the closure member. The closure member is movable vertically through a certain distance, while maintaining the furnace chamber closed by a suitable seal, to permit of either circulating the air in a closed path in the furnace chamber itself, or through the furnace chamber and between the two walls of the outer shell.

In the drawings:

Figure 1' is a view in vertical section through a furnace embodying our invention, and

Fig. 2 is a view partially in front elevation and partially in section, showing a second position of the two parts of the furnace structure.

We have elected to show our invention as applied to an annealing furnace having a vertical chamber, but wish it to be understood that our invention is not limited to an annealing furnace nor is it limited to a vertical-chamber furnace.

A furnace assembly H includes an outer sheet metal shell l3 and an inner sheet metal shell IS, the two shells being nested one within the other with a suitable air space I! therebetween, this air space extending not only between the Vertical portions of the inner and of the outer shells, but also between the bottom portions of these shells.

We may provide suitable I-beam members I9 in order to support the inner shell and other parts located therein and to be hereinafter described, in the outer shell. We provide also a suitable base member 2i and supporting members 23 extending between the base 2! and the outer shell l3. It is to be understood that the beams [9 are so designed and located as to permit of free passage of air in the space I! at the bottom of the furnace structure for a purpose to be hereinafter set forth.

Within the inner shell l5 we provide a plurality 5 of blocks or bricks 25 of a suitable heat-insulating material capable of withstanding relatively high temperatures and we may provide granular heat-insulating material 29 peripherally of the furnace as shown in this figure of the drawings. 10 For illustrative purposes, it may be assumed that the furnace structure is substantially circular in horizontal section, although our invention may be applied with equal facility to furnaces of other shapes in cross section. The bricks 15 or blocks 25 are so arranged as to define a furnace chamber 3| which may be of any suitable or desired shape and size. A conduit 32 provides a connection between the cooling chamber l1 and the furnace chamber 3! to permit of the 20 passage of air or gas from one to the other.

Means for heating the furnace chamber and any contents placed thereinare constituted by electric heaters 33 which may extend peripherally of the chamber 3i and be directly supported by 25 blocks 35 of electric-insulating material located one above another, so that the heating element will have the form of a double helically wound member, the blocks 35 being supported by rods or bolts 31 of a high-temperature-resisting ma- 30 terial. The upper ends of the respective bolts 31 may be supported from supports 39 all of which may be combined to constitute an annular ring or which may be in the form of individual supporting members held in a manner not set 35 forth in detail, on the uppermost of the blocks Suitable nuts may be associated with the rods 31. in order to hold the blocks in close operative engagement with each other and supporting the heating resistor. 40

Means for removably supporting metal objects to be annealed or otherwise heat treated com prises a plurality of foraminous dishes or baskets 4! which may be located one on top of another and within a tubular drum 43. Drum 43 includes 45 a substantially cylindrical wall which is imperferate, a perforate bottom 45 and an upper laterally-extending flange 4! to which may be secured a plurality of eye-bolts 49 to permit of placing container 43 in chamber M or of removing it 50 therefrom. The walls of member 53 extend below the perforate bottom 45 and a plurality of openings 5! are located in this bottom portion of the wall to permit air or other gas to pass therei' hrougn. 55

A cover 53 includes a suitable metal cover plate 55 and an annular sheet metal wall 5'! within which are located two kinds of heat-insulating material shown respectively at 59 and 6! The cover 53 includes also a bottom plate or wall 53 of sheet metal suitably secured to the annular wall 5'! as by means of either a plurality of short angle-bar members 65 or an annular member of angle-bar shape. at the central portion thereof as is indicated at 8'! in the two figures of the drawings.

The cover is arranged to be movable upwardly and also to swing on its support in order to uncover the furnace chamber 3! to permit of introducing material into and removing it from the furnace chamber 3 l as was hereinbefore set forth. The covermember 53 has a bracket 69 secured thereto at one point peripherally thereof, which is so designed as to include a pair of ball bearings 1! and 13 supporting the cover member 53 on the upper end of a short and relatively heavy shaft or stud 15. The shaft 15 may be integral with, or secured to, an upper guide member I? which has depending therefrom and secured thereto a second guide member 19 in the shape of a plate which moves within a tubular member 8!. A rackbar 83 is secured to the bottom of plate 19- and is actuated in a vertical direction by means of a small pinion 85 mounted on a shaft 8'! which may be turned by a hand wheel 89. The shaft 8! is supported in a bearing member whose lower end is secured to a plate 9!, fixed on the upper end of a tubular member 92, which is located within member 8 l. The tubular member 8'! is supported within an upper bracket 93 and a lower bracket 94 in such manner as to hold it rigid relatively to the rest of the furnace structure and to permit of moving the cover and the members or parts directly operatively associated therewith in either a vertically upwardly or a vertically downwardly direction. A plate 95, having a recess or an opening therein and secured to cover member 53, cooperates with a rod 9'! on the outer shell !3 and extending above the upper edge thereof, to aline the cover member with the body of the furnace.

Means for sealing the furnace chamber against the outer air includes an annular trough-like structure 99 located near the top of the outer shell !3 and an annular sheet metal member It]! secured to the bottom plate 53. The trough-like member 99 may be filled with either a liquid sealing material such as a high-temperature resisting oil or with sand or some other powder by the use of which a substantially air-tight seal may be obtained. It may be here pointed out that the metal sheet l9! aswell as the trough 99 are relatively deep in order that the cover may be moved vertically upwardly a small distance on the order of several inches without breaking the said seal.

A- pair of members Hi3 and I65, of channel shape, are secured to the top sheet metal. cover 55 and have secured thereon a plate l5! upon which is mounted a vertical shaft motor I39 whose shaft extends downwardly through a suitable opening in plate It? and may have a coupling half I! secured thereon. A second coupling half I3 is located on the upper end of a fan or blower shaft H5, which blower shaft may be supported by a thrust bearing H6 and may extend downwardly through the cover and therebeyond and have a fan or blower structure I! secured thereto to rotate therewith. A guide bearing may be provided in a sleeve, H9 near the lower end of shaft H5 and since this guide bearing is located The wall 63 is bent upwardly through the container 53.

quite closely adjacent to the heat treating chamber 3!, we may provide an annular cooling chamber 2! around the sleeve H5. The walls of the annular cooling chamber i2! may be integral with a vertical member !23 of generally tubular shape which may be utilized for holding the top plate 55 and the bottom plate 53 in properly spaced relationship to each other. A pair of conduits I25 and !21 may communicate with the annular cooling chamber :2! to permit of passing a cooling fluid therethrough.

We may provide also a pyrometer tube !29 in order to obtain or observe the temperature of the furnace chamber.

Let it be assumed that our invention as shown in the two figures of the drawings has been applied to an annealing furnace. The material and the respective baskets 4! having been placed in the tubular casing 43, the material, the baskets and the container therefor may be placed within the furnace chamber 3! by any suitable means such as a crane and a chain attached to the eyebolts 49. The furnace cover, which of course had been turned away from the furnace structure during the operation of placing the material in the chamber, is now turned on the ball bearings H and 13 until the recess in plate 95 substantially registers with rod 9? after which hand-wheel 83 can be turned in such direction as to lower the cover structure until it occupies the position shown in Fig. 1 of the drawings where the bottom plate 63 engages the top of the refractory heat insulating structure hereinbefore described. The heating element 33. may now be energized from a suitable source of supply of electric energy through the leading-in conductors I30, only one of' which is shown in the drawings, with the result that the temperature within the furnace chamber 3.! will be increased to a desired value. If it' is desired to provide a non-oxidizing or neutral atmosphere within. the furnace chamber, this may be accomplished by permitting the desired kind of gas to enter the furnace chamber through the valved inlet !3!, the gas. entering chamber 3! through the conduit 32 connecting it with the space I"! between the two walls.

As it is desirablev to elfect uniform heating of the material in the respective baskets 4! in as shorta time as may be possible, we now cause operation of the fan I l! by energizing the motor l9!) with the result that air is drawn upwardly within the container 43, forced radially outwardly over the flanges 4'? and downwardly in the annular portion, of. chamber 35 in which the heating element 33 is located and then inwardly through the openings 5! and then upwardly We thus provide a closedpath for the air or other gas within the furnace chamber 35, and the general result of this circulation of air or gas is to cause more uniform and quicker heating of the material to be annealed or otherwise heat-treated.

If steel articles have been heat-treated and have been raised, to a relatively high temperature, it is generally undesirable to subject them to the outer air inorder to aid in quickly cooling them because of the oxidizing effect of the air upon the steel or iron objects.

In order to effect relatively quick cooling, we now operate the hand-wheel 89 in such manner as to raise the cover structure several inches above its original position, the positions of the cover and of the furnace structure being that shown in Fig. 2 of the drawings. The operation ofthe fanor blower ll! being continued, the air 75.

or atmosphere within the furnace chamber will now be caused to move in a difierent path from that in which it moved when the parts were in the positions shown in Fig. 1 of the drawings. The air will still be drawn upwardly through the solid wall container 43, be moved radially outwardly and will flow through the clearance space between the bottom of the cover and the top of the furnace structure, which space has been designated by numeral 533 in Fig. 2 of the drawings. From there the air or gas will be forced into the annular cooling chamber ll, downwardly therein and through the bottom space H, upwardly through the connecting conduit 32 and then again through the container 43. It is obvious that not only does the quiescent air space I! act as a heat-insulating means for preventing loss of heat radially outwardly during one part of the operating cycle of the furnace, but that it also serves as a cooling chamber by reason of the fact that the temperature of the outer thin metal shell 13 is relatively low. It is thus obvious that the air or gas within the still closed furnace structure shown in Fig, 2 of the drawings will be cooled relatively rapidly by being circulated in a different path from that in which it moved during the time when the furnace structure, and particularly the cover thereof, was in the closed position shown in Fig. l of the drawings. It is to be noted further that the seal provided by us is such that even with the cover member located in its partially raised position, the furnace chamber 3! will be closed against the outer atmosphere.

The device embodying our invention thus provides relatively simple means for circulating air in one path within a closed furnace chamber during one part of a heat-treating cycle in a furnace and of causing it to flow in a different path in another cycle or part of the operation of the furnace where it will be subjected to the cooling effect of the surrounding atmosphere to thereby aid in more quickly reducing the temperature of the material which has just been heat-treated.

While we have illustrated and described a vertical chamber furnace, our invention is not limited thereto as it may be applied equally as well to a horizontal chamber furnace with the same general results.

Various modifications may be made in the device embodying our invention without departing from the spirit and scope thereof, and we desire therefore that only such limitations shall be placed thereon as are imposed by the prior art or are set forth in the appended claims.

We claim as our invention:

1. A furnace structure including refractory walls enclosing a furnace chamber on all but one face thereof, a double-wall structure substantially coextensive with the refractory walls and surrounding the same, a cover for the open face of the chamber, and means for causing circulation of gas through the chamber, between the cover and the adjacent face of a wall and through the double wall structure.

2. A furnace structure including walls and a movable cover enclosing a furnace chamber, two spaced nested casings surrounding the walls, a seal between the cover and the outer casing, and means for causing circulation of gas through the chamber, between the cover and the adjacent face of said walls and between the spaced nested casings. I

3. A furnace structure including walls and a cover enclosing a furnace chamber, means for moving said cover relatively to the walls, two spaced nested casings coextensive with and surrounding the walls, a seal between the cover and the outer casing, a duct between the chamber and the space between the two casings, and means to cause gas to circulate in the furnace chamber alone when the cover engages the face of the walls and to cause gas to circulate through the chamber, between the cover and the face of the walls, through the space between the spaced casings and the duct when the cover is raised out of direct engagement with the face of the walls.

l. A furnace structure including walls and a cover enclosing a furnace chamber, said cover having two operative positions relatively to the walls, a seal between the cover and the walls for preventing access of outside air to the chamber in either position of the cover, two spaced nested casings outside of the walls, and means in the furnace chamber for causing gas to circulate in the furnace chamber alone when the cover is in one of its operative positions and to circulate through the furnace chamber and between the spaced casings when the cover is in the other of its operative. positions.

5. A furnace structure including side and bottom walls defining a furnace chamber, a top cover having two vertically different operative positions relatively to the walls, an air chamber on the outside of the side and bottom walls constituted by at least an outer casing around the walls, and means for moving air in the furnace chamber only when the top cover is in the lower of its operative positions and for moving air through the air chamber and through the furnace chamber in sequence where the top cover is in the other of its operative positions.

6. A furnace structure comprising walls and a cover enclosing a furnace chamber, a gas cooling chamber located externally of the furnace chamber, said cover having two operative positions and means within the furnace chamber for moving gas in the furnace chamber only in one position of the cover and for moving gas in the furnace chamber and in the gas cooling chamber in another position of the cover.

7. A furnace structure comprising walls and a cover enclosing a furnace chamber, said cover having two operative positions relative to the walls, a gas chamber around a portion of said r walls, means for moving gas in the furnace chamber only when the cover is in one position and for moving gas through the furnace and the gas chamber in a closed circuit when the cover is in its other position.

8. A device as set forth in claim '7 which includes means effective in both positions of the cover to prevent access of external air to the furnace chamber.

9. A device as set forth in claim 7 in which the gas-moving means includes a fan supported by and movable with the cover.

10. A device as set forth in claim 7 in which the gas-moving means includes a fan on the under side of the cover, a drive shaft for the fan extending through the cover and means in the cover for cooling said drive shaft.

11. A device as set forth in claim 7 which includes fluid cooling means in the cover adjacent the under surface thereof.

12. A heat treating furnace comprising a double wall gas-cooling chamber of cup-shape, refractory walls of cup-shape in the gas cooling chamber defining an open top furnace chamber,

a conduit extending through the bottom refractory wall and connecting the gas-cooling chamber and the furnace chamber, a cover for the furnace having two vertically-spaced operative positions relatively to the double-wall gas cooling chamber, a gas seal between the cover and the double-wall chamber effective in both positions of the cover to prevent entrance of outside air to the chamber, and a fan depending from the cover into the furnace chamber for causing continuous circulation of gas through the cooling chamber, conduit and furnace chamber in sequence when the cover is in its raised position.

13. A heat-treating furnace comprising an outer open top gas-cooling chamber, walls defining open top furnace chamber within the gas-cooling chamber, a conduit connecting the two chambers, a cover for both chambers having two vertically-spaced alined operative positions relative to said chambers, an open top and bottom work container in the furnace chamber, said container having a solid peripheral wall, electric heating units between the work container and the wall of the furnace chamber, a fan depending from the cover into the furnace chamber and effective to cause circulation of gas through the work container and past the heating unit in a closed circuit in one position of the cover and to cause circulation of gas through the furnace chamber, the gas-cooling chamber and the conduit in a closed circuit when the cover is in its other operative position.

14. A heat-treating furnace structure comprising two nested spaced interfitting walls defining an open-ended gas-cooling chamber, refractory walls within said nested walls defining an open-ended furnace chamber, the open ends of both chambers being located at the same end of 5 the furnace structure, a conduit connecting thetwo chambers at their closed ends, a cover for both chambers having two spaced axially-alined operative positions relatively thereto, and a fan supported by the cover and selectively effective to cause gas to circulate in the furnace chamber only when the cover is in its first operative position and to cause gas to circulate through both chambers and the conduit when the cover is in its second operative position. 1;

15. A heat-treating furnace structure comprising two nested spaced interfitting walls defining an open-ended gas-cooling chamber, refractory walls within said nested walls defining an openended furnace chamber, the open ends of both chambers being located at the same end of the furnace structure, a conduit connecting the two chambers at their closed ends, a cover for both chambers having two spaced axially-alined operative positions relatively thereto, and a fan supported by the cover and movable therewith and controlled by the position of the cover to selectively cause circulation of gas in the furnace chamber alone and through the two chambers and the conduit.

WILLARD ROTH. FRANK X. KERIN.

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