US1485151A - Furnace - Google Patents

Description

v SSJS L. ROESSEL ET AL Feb. 26

FURNACE Filed May 4. 1921 Patented Feb. 26, 1924.

i' STATES LOUIS BOIEEL, OF BROOKLYN, NEW YORK; .ARTHUR E. BELLIS, OF SPRINGFIELD,

TO BELLIS HEAT TREATING COMPANY, OF NEW' HAVEN, CONNECTICUT, A. COR,-

POBATION OF CONNECTICUT.

FUENACE.

Application tiled Hay e,

To all whom t may concern.'

Be it known that we, Lome RoEssnL, a citizen of the United States, and a resldent of Brookl n, in the county of Kings and State of ew York, ARTHUR E. Banus, a citizen of the United States, and a resident of S ringiield, in the county of Hampden and tate of Massachusetts, and CHARLES S. COLLINS, a citizen of the United States, and a resident of Bronx, in the county of Bronx and State of New York, have invented new and useful Improvements in Furnaces, of which the following is a specification.

This invention relates to furnaces and more particularly to furnaces of that general type which are used in the heat treatment of metals.

Generically considered, our present invention comprehends the provision of a mult-iple type furnace designed for the purpose of most eiiciently and economically utllizing the generated heat in the treatment of metals or metal alloys in liquid baths.

More particularly, in one embodiment of the invention, we provide a battery of furnace chambers which may be produced in the form of one unitary structure, or may consist of several independent furnace structures together with means for supplying a reducing atmosphere for the high temperature treatment of the metal or metal alloy to one of the furnage chambers and means for conducting the high temperature gases to either one or all of the other furnace chambers for the treatment of the metal or metal alloy at relatively lower temperatures. In general it is our aim and purpose to provide a multiple furnace structure of the above character which? may be advantageously employed for first pre-heating the metal object, then subjecting the same to a high temperature heat treatment, and sub 1921. Serial No. 66,780.

ment of our invention and in which similar reference characters designate corresponding` parts throughout the several viewsigure 1 is a lon 'tudinal sectional view throu h a .multiple c ambered furnace structure isclosing a preferable embodiment of the invention.

Figure 2 is a topl plan view.

'Fi re 3 is a transverse section taken on the line 3 3 of Figure 2.

In the resent art of heat treating high speed stee s, it is the usual practice to first heat the steel object in a pre-heatin oven type of furnace and then to trans er the object to a high temperature oven type furnace where it is heated to a temperature of 2100 degrees F. to 2200 degrees F., as may be required owing to the composition of the particular metal alloy. The metal piece or object after being subjected to the high temperature heat treatment is then suddenly quenched in an alloy bath at ordinary room temperature, the piece is finally drawn in a lead bath to about 1100 degrees F. This practice is sometimes modified by first preheating in an oven type furnace, then heating the piece to the required hi h temperature in a bath of barium chlori e, and then 'uenchin a ove re erred to.

A further development in' the present art is to pre-heat the metal piece in an oven type furnace and then subject the piece to the required high temperature treatment in a high temperature oven type furnace, then quench in a lead bath at about 1100 degrees F., and finally subquench in oil. This high temperature quench of the metal piece renders unnecessary the drawing operation after the quench.

In the operation and use of our new furnace structure for the high temperature heat treatment of metals, it is our practice to employ either one hi h temperature bath con- '-CHUSLTTS, .AND CHARLIE S. COLLINS, .OF BRONX, NEW YORK, ASSIG-NOBS A and drawing in an oil bath as I sisting of fused sa ts, preferably of eutectic v lication of Arthur E. Bellis filed, Septemlier 24, 1920, Serial No. 412,588, and one quench bath also consisting of an eutectic mixture of fused salts likewise referred to in said pending a plication, or on the other hand to use a preeating bath likewise consisting of an eutectic mixture of fused salts, a high temperature bath of fused salts and a quench bath of fused salts, each of the said salt baths having the characteristics of an eutectic as described in the said Bellis application.

In order to obviate distress or physical deteriorationv of the metal pots or containers for the salt baths, and more particularly those used in' the high temperature chamber of .the furnace, We employ the special Crucible construction of Patent No. 1,358,816 granted to Arthur E. Bellis, November 16th, 1920, and the protecting or sealing rings as shown and described in the pending application of Charles S. Collins, .Serial No. 406,870, filed August 30th, 1920.

Referring now in detail to the accompanying drawings 5 designates the body of the furnace structure which may be of fire brick, masonry or other more or less refractory material, said body structure being reinforced and supported by the metallic frame Work 6 and mounted upon a plurality of-pedestals or supports 7. In the present illustrated embodiment of our invention We have shown this furnace structure as provided with 3 chambers, namely, a pre-heating chamber 8, a high temperature chamber 9 and the quench chamber 10.

These chambers may be of any desired size and shape. Each, chamber opens through the vtop of the furnace and through such opening the bath containing pot or crucible generally indicated at 11 may be inserted. Preferably the pot which is arranged in the high temperature chamber 9 is provided with an exterior wall 12 whichis more or less resistant to oxidizing atmospheres and serves as a protection for the inner liner or metal pot proper, in accordance with the patented Bellis crucible construction previously referred to.

A 'suitably proportioned mixture of air and gas is supplied to the high temperature chamber 9 through the medium of the burners 13. .In the present disclosure we have shown three of these burners arranged in op osite sides of the furnace structure and de ivering the 4mixture of air and gas into the chamber atopposite sides of the crucible arranged therein. An opening indicated at 14 is formed through one side of the furnacethrough' which a lighted taper may be inserted for the purpose of igniting the gaseous mixture issuing from the burners.

Auxiliary burners 15 and 16 respectively areJ provided for the preheating and quench- 'ing chambers of the furnace'structure, and

Laender the lighting openings 17 and 18respectively communicate with these chambers through which the taper may be inserted for igniting the gas. However, as will be hereinafter explained these auxiliary burners are not used except upon the start of operations or when it is desired to increase the temperatures in these chambers.

The furnace structure 5 is provided with the lpassages 19 and 20 respectively which connect the central high temperature chamber 9 with the chambers 8 and 10, said passages being located at the lower ends of the furnace chambers. The outlet iues or passages 21 and 22 respectively extends upwardly through the furnace structure from the passages 19 and 20 and open through the top of the furnace. The up er ends of these outlet flues may be closed y means of suitable plates or closures. Additional outlet passages 23 and 24 respectively connect with the upper ends of the preheating and quench chambers 8 and 10 and open through the top of the furnace structure. Suitable dampers indicated at 25 are provided for the purpose of controllingl the passage of the products of combustion from the central preheating chamber 9 into the passages 19 and 20, thus enabling all of these 'products to be passed into either one of the chambers 8 or 10 or to be equally distributed to said chambers.

The furnace structure is4 further provided With drainage openings 26 communicating with the lower end of each of the chambers through which any overflow from the crucibles may be drained 0H'.

In the operation of our improved multiple type furnace as above described, the salt bath solution contained in the crucible in the central chamber 9 of the furnace is .maintained at a temperature of from'2000 to 2300 degrees F., as may be required by lthe particular work in hand. This temperature of thel bath solution necessitates a combustion chamber temperature of about 2500 to 2700 degrees F., and the roducts of combustion leaving this cham er are usually above 2200 degrees F. If these gases were allowed to escape to the atmosphere without utilizing the heat energy contained therein, a great waste of fuel would result.

'Howeveig by means of our improved furnace structure, We conduct these high temperature waste gases from the central chamber 9 to the preheating chamber 8 vand the quench chamber 10. We have found in practice that there is suiiicient heat contained in these waste gases to maintain the required temperature of the preheating bath solution. namely, approximately 1600 degrees F.. and likewise the required temperature of the quench bath solution, namely, approximately 1300 degrees F. These temperatures in the preheating and quenching baths may be of air.

attained at thel start of operations by using the auxiliary burners 15 and 16 respectively or if at any time it is desired to increase these telnperatures then the auxiliary burn-l ers are employed. The temperatures in the pre-heating and quench chambers can' also be varied and controlled by the proper manipulation of the dampers 25.

the metal ofthe pot and cause scaling.

Furnaces as now used in the'high temperature treatment of metals are provided with vents at the top of the furnace chamber so that free air can pass through the furnace, such air entering at the'burner openings at the bottom of the furnace chaniber. This free atmospheric air in its passage through the chamber causes rapid oxidi'zation and scaling of the' pot wall after the fuel h as been turned off and while the pot and its contents are cooling.

In the operation of our new furnace construction we firethe central high temperaf turechamber in the upper area and the waste gases are passed to the end chambers and' then out to the atmosphere at the top of these -end chambers] It will therefore be manifest that there is no draft -effect through this central chamber to cause atmospheric air to enter the furnace when the fuel supply is cut o ff. In order to control and maintain a reducing atmosphere in the furnace chamber, we employ a system which produces a constant ratio of air to gas irrespective of the rate of fiow, and adjust the system so as to provide a reducing atmosphere. Our preferred embodiment of such a system of firing is fully shown and described in Letters Patent 1.290.513 granted January 17, 1919, to Charles S. Collins and Louis Roessel.A The adaptation of this proportional regulating system for the air and `gas flow to our irnproved furnace structure will be readily perceived upon a perusal of the said patent.

From the foregoing". description con- K sidered in connection with the accompanying drawings, the construction,.manner of operation and several advantages of our 1mproved multiple type furnace will be' clearly understood 'IVe ,have successfully demonstrated in practice that such a furnace construction results in great. economv in the high temperature heattreatment of It is therefore evident metals, first bythe appreciable reduction in fuel consumption due to the fact that -a great part of the heat lin thegases leavin the high temperature chamber is utilize for heating the llower temperature preheating and quench bath chambers, and secondly, by prolonging the life of the pots or crucibles which arel used in connection with the furnace. The maintenance of proper' temperatures inA the three furnace chambers is always under the control of the operator by the simple manipulation of the \fuel flow regulating valves and the adjusti ment of the waste gas control dampers.

In the foregoing description we have set forth in detail the several structural features of'a multiple typelfurnace which we have found to give highly satisfactory results. Nevertheless, it is to be understood that this invention might also be exemplified in numerous other furnace structures. Thus for instance,'instcad of producing the furnace in theform of a single unitary structure with the. series of. chambers, We'might provide separate and distinct furnaces each having a single chamber,v more or less widely separated from eachother and connected by suitable pipes or conduits constituting the equivalent of the Waste heat conducting passages or ilues. Further, as will be readily apparent to one skilled in the art the several detail parts of 4the irn- -proved furnace might be variously changed or modified, and we therefore lreserve the privilege of resorting to all such legitimate alterations in the form, proportion and relative arrangement of the several elements of the described construction as may be fairly embodied within the spirit and scope of the invention as claimed.l

IVe claim: l 1. A furnace. for heat treating metals g having a high temperature chamber from which free air is excluded, and preheating and .quench chambers ,open to the atmosphere, means for supplying a combustible .fuel mixture to -the high temperature chamber, and means for transferring llU . the products of combustion from said high A 2. In the heat treatment of metals, a high y temperature furnace .chamber and preheating and quenchA chambers, each of said chambers adapted to receive a Crucible containing a fused salt treatment bath, means of .affording communication between the 'several chambers at their lower ends, and meansfor supplying a combustible fuel miX- ture 'tol the hightemperature chamber, the productsvf combustion being conveyed from said chamber through the communicating means to thepreheating and quench chambers.

3. In the heat treatment of metals, a furn sages connecting the severall 'chambers to each' other at their lower ends, sald high temper-'a1 ture chamber-being closedto the atmospherenace structure 'having -a hi h 'temperature chamber and preheating an quench chambers,- each of said chambersadaptedtc receive a crucible containinga heat treatment bath, said furnace structurehaving passages connecting the several chambers to each other at their lower ends, said high temperatur-e chamber being closed to the atmosphere and the reheating chamber and quench chambers avingvent openings at their upper ends and a plurality, of fuel burnersfor the high4 temperature chamber, the products ofcombusti'on being 'conducted by said pasto the preheating and .quench chambers. f Y

A. In the heat treatmentof metals, a fun nace structure having a' high temperature chamber and preheating and-quench chambers, each of said 'chambers'adapted to lreceive a crucible containinga heat treatment bath, said furnace 'structure having passages 'bath solution and a passage connecting said chambers to each other at their lower ends, one of said chambers being closed to the exterior air and the other of said chambers having a vent opening at its upper end, and a plurality of fuel burners 4for the first named chamber arranged above said connecting passage to heat the contents of the crucible to a high temperature, the products of combustion being conducted by said passage' from said high temperature chamber to the other of the chambers to heat the `con tents of the crucible therein -to lower temperature.

6. In the-heat treatment of metals, a furnace structure having spaced 'chambers each adapted to receive a crucible containing a bath solution and a passage connecting said chambers below the crucibles to each other at their lower ends, one of said chambers being closed to the exterior air and the other of said chambers having a vent opening at its upper en'd, a plurality of fuel burnersfor the iirst named chamber to heat the contents of the crucible to a high temperature`- the products of combustion being conducted by said passage from said high temperature a relatively chamber to the other of the chambers to heatl the contents of the crucible therein to a rel.

atively lower temperature, and means for said chambers' attheiilower ends, the fur# nace structure being Q urth'er prov1ded with an outlet li'ue 'communicating with said pas sage, Aone of'saidA 'chambers being closed to the exterioiffair andthe other chamber hav'd chamber to heat thecontents of the crucible l.therein to al 'high temperature, the products of combustion being conducted from said high ,temperature chamber to the other of.

said chambers toheat the contents of the crucibletherein to a relatively lower tempera-ture. l

8. ln the heat treatment of metals, .a furnace structure having a hi h temperature quench chamchamber and preheating an bers, each of said chambers adapted to receive a crucible containing a treatment'bath,

sages connecting said chambers to each other at their lower ends, the high temperature chamber being closed' to the exterior air and the preheating and lquench ,chambers having vent openings at their upper ends, a plurality of primary burners for the high temperature chamberauxiliar burners for the preheating and quench c ambers, the products of combustion being conducted by said passages from the high temperature chamber to the preheating and quench chambers, and means for controlling the distribution of the products of combustion'to the latter chambers.

Y 9. In the hea-t treatment of metals, a furnace structure having a high temperature chamber and preheating and quench chambers, each of said chambers adapted to receive a crucible containing a treatment bath, said furnace structure 'provided with passages connecting said -chambers to each other at their lower ends, the high temperature chamber being closed tothe exterior air and the preheating and quench chambers having vent openings at their vupper ends, a"

plurality of primary burners for the high temperature chamber, auz'riliary burners for the preheating' and' quench chambers, the products of combustion being conducted by said passages fromthe high temperature chamber to the preheating and quench cham-- bers, said furnace structure being further provided with outlet' flues communicating with'said connecting passages, and means for controlling the distribution of the products of,combus`tion Vto the latter chambers.

10. In the art of heat treating metals by means yof a plurality of fused salt solutions maintained at relatively different tempera fing la vent opening atl its upper end, and a 'plurality of-fuel burners for the first named Isaid furnace. structure provided' with pastures; the method which consists in heatn testimony that We claim the fore oing ing the high temperature bath solution conas oui` invention, and we have signe oul taining crucible in a reducing atmosphere names hereunder. to the requisite temperature and utilizing the 5 exhausted heating medium for heating the LOUIS ROESSEL.

crucibles containing the relatively low tem- ARTHUR E. BELLS. perature bath solutions. CHARLES S. COLLINS.

t ma

Images