US2638333A - Continuous furnace - Google Patents

Description

May 12, 1953 F. o. HESS 2,638,333

CONTINUOUS FURNACE Filed Aug. 25, 1950 *Qii 35 l3 5 INVENTOR.

FREDERIC O. HESS ATTORNEY.

Patented May 12, 1953 oonrmooos FURNACE I Frederico. Hess,, Philadelphia, Pa., assignor to Selas Corporation of America, Philadelphia, 2a. acorporation of Pennsylvania 7 Application August 25, 1950, Serial No. 181,336

' This application is a continuation-in-part of my application Serial Number 103,371 filed July 7,1949and now abandoned.

The present invention relates to the heat treating of metal, and more. particularly to the, construction ofa housing structure to be used between thefurnace units of." an elongated continuous heattreating furnace.

One form of continuous metal heating furnace that is in use at thepresent timecomprises a number of small furnaceunits that are aligned axially. with each othernace units are used in each installation to raise the work .beingheated tothe desiredtemperature. Each of the furnace units is cylindrical or barrel shaped andisprovided with a similarly shaped chamber-that is fired to a high temperature... The ends of 'thechamber are provided withaxially aligned openings throughwhich the work'enters and leaves. The furnace units are mounted in axial alignment, and a conveying 3 Claims; (01.263-3) Enough of these furroller-is placed :betweeneach unit to forward the work; In this manner .the ,workis progressively heated. as it moves from end to end of the furnace. l

When in operation-the. hot productsof combustionare exhausted through the ends of the furnace units in what is generallycalled a stingout? to protect the heated work from the oxidizing effect of the atmosphere. 'As the hot gases leaventheifurnace units they begin to rise, 50 that the. lower portion of the workis not covered by asgthick a layer of gases asis the upper portion. This condition is augmentedby the'fact that the hot gases have a tendency to create an upward draft of cold air between the furnace units. This airchills the lower portion 9f the protective coat or sleeve of combustion gases around the work, so that the work is unevenly heated as it is passing between the furnace units.- It has been found in some instances that the temperature of, the work actuallydropped slightly as it was passing from on furnace unit to the quently the sting-ou I H I I veying. mechanism, usually water cooled, and at times heats up the supporting means and bearings therefor to an objectionable extent; It is an object of the invention to provide a shield or housing around the work and itscon- .veying mechanism between furnace units of a sectional furnace structure to protectthe work Figure 1 and next. Quite fre impinges upon the .con

from loss of heat and uneven heating due to draftscreated between the furnace units by the sting-ou and by excessive radiation to the atmosphere. This housing, in effect, provides a .sa e n wee h at ns .z n

=. its al o-an O ec -.'t1 .e.nre nt n e tiq to provide a shield or housing between the furnace units that will control the sting-out so that it will protect the-work being heated, but Will not unduly heat up the various parts of the conveyor'su'pporting mechanism. It is a further object of the' invention to provide a shield or housing between-the furnace units that will, in effect, join them into a single elongated structure that isindividually fired in a plurality of zones." 1p: V

u'I'he shield or housing is provided with openings so that it serves as astack through which the products of combustion arewithdrawn 'between the furnaceunits or zones. By varying the size of the openings the pressure of the gases around the-work and inthe furnace chambers may, to some extent, be varied. It is, therefore, a further object of the invention to provide a means for controlling the flow of exhaust gases from the furnace units to control the pressure, in the furnace chambers and the space between them.

The various features of novelty which characterize myinvention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention,'however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in whichI have illustrated and described a preferred embodiment of the invention. I

in the drawings:

Figure 1 is a side view showing a continuous heat treating furnace, with a portion thereof in section; I i v Figure. 2. is a view taken on the line 2j2 of v Figures 3 and 4 e ach are views similarto Figure.2 and show different modifications; of the invention. v p Referring to Figure l, thereis shown a section of a continuous heat treating furnace which is formed of a number of furnace units 3. These units are mounted on suitable supports 2, that are in' turn fastened to. a foundationt. The foundation may take the form of apair of elongated channels, or it may be the foundation of the building in which the furnaces are being used. The numberof furnace units that are contained in each 'continuous. furnace or furnace system will vary depending upon the temperature to which the work is to be heated and depending upon the size and analysis of the work. In any event,. each of the furnaces includes a number of furnace units l 1 ,Each of the furnace units l is in effect a small lined with suitable refractory material that is: capable of withstanding the heat to which. the

furnace will be fired and is provided with a chamber 1', having axially aligned openings 8?, extend-- ing through each of the heads; The furnaces are fired with any suitable type of burners that are capable of maintaining: the temperature to:

which the work is to be raised. It is preferable, however, that the burners 9 be of the type disclosed in application Serial Number 56,616, filed @ctoben 2.6:, 19.48 by A.. Furczyk, now Patent No. 2;5fi-1r,17;93.;

In the-operation of a. furnaceof thistype, elonated Work; to be heated is fed by suitable conveyingz, means, intoone; end of the furnace and sucoessittely through the variousifurnace units and out, theother end of; thefurnace: During, the time: that... the; work. passing through; furnace units. it. is. being; progressively heated; to. bring; it to the temperature which is desired. In order than. the. work may be forwarded through. the furnace, there is; provided between. each: of. the furnace units a conveying. roller H, as is: shown best-in Figure; 220i. the drawing. This roller. may be water cooled, if desired; and in any event" it is mounted on a. shaft 12: that is journaled for. rotationzin: bearings. I 3: whichare attached to suit able blocks. I542 extending forwardly from: the supporting platesfii: for the furnace units. It is noted that each of the furnace uni-ts has=supports oni-t'for one-conveyingroll l t. Each of the conveying rolls is driven at the same speed, and" for this purpose is. preferably driven by an electric motor: I 5"; that is attaohed tothe-end ofshaftl2 and" is: mounted upon a bracket suitably secured to=theend -plate Each conveying'roller ll may hayeitsaxisparallel to the faces of'the adjoini-ng furnaces, orat an angle-thereto;v In-thefirst case the i work will be moved through the furnace without rotation. Inthe latter case-the work will rotatedabout its: axis as it is being moved axially. This type of conveyor roll' mounting is frequently used to insure even heating around the" work.

When thefurnace system is being fired the burners 9 and the walls of the chambers 1* are heated to'incandescence so thatradiant heat is projected against all sides of the work passing through the furnace chambers. When theburners are flred largevolumesof burned gases result as the products of combustion, and these gases-areexhausted at high velocity through the openings& at the ends ofeach furnace chamber. These hot products of combustion are called a 4 of combustion meet each other between the fur nace units and spread to both sides as well as upwardly. In either case there is a tendency to induce a draft of cold air upwardly across the conveying roll l2 and that portion of the work extending between furnace units. Not infrequently, also, thehot gases mushroom out so that the bearings in which the shaft I2 is rotatable are heated to an excessive temperature. Some meansmust, therefore, be devised to insure that the exhausting products of combustion will at all times completely envelop the Work as it is passing between the furnace units without inducing a cooling draft across the work, but will neverth'eless. be. prevented. from impinging against the bearings in which the shaft I2 is mounted. Such a: means in combination with the furnace units themselves forms the primary subject matter of this: invtm-tionzv and; will now bedescribed in detait particular reference to Figures 1: and 2:.

By reference to Figures I and 2 it willnbe seen tl'iat: there is. provided. ashield or housing 2| which completelysurroundsthework. andiitsvsup porting roller. The: housingv Z1 is supported jointly. by the: end plates 5 or the water jackets 6 of adjoining furnace units: and includes a pair of? refractory" blocks 22; whichv extend downwardly below. the shaft". ll of the conveyor roll. The upper surface of each of. these: blocks has a semi-circular cut in. it ta receive:- the: ends of the shaft that extend: beyond-a the: housing... These blocks-are supported by angles: that: are: welded to the faces. of. the furnace units: and: are maintained' in: position by: plates" or. lugs. 23' which project forwardly from. each. the; furnace: unit's. Thetop-portionof thehousing comprises a semicylindrical member 2 3: which: engages. the top edges of blocks 2'2 and extends. around the: upper portionof the openings 8% of the: furnace: units. Thaw-eight of this member: issupported: by'anagi'es 25' that. are welded to: the faces: of. the. furnace unit's; Each: side of member 265 is provided with a semi-circular cut out portion cooperating with the similar portions-of blockstZZ to form. an

opening through which the shaft I'Z' extends;

Members 25 are made of suitable refractory Ina-.- terial 21 that are backed up by meta'l' sheeti work 2th in accordance with standard furnace: cons-tructi'on practice. The upper part of the member 26- is provided with an upwardly extending projection which forms a stack 29 through which the products of combustion are=exliausted Ex haustionof these prodiiets of combustion iszcom sting-out" and serve the purpose" of completely enveloping the workas it is moving between a pair of the furnace units so that the surface of the work cannot become oxidized; Since the products of combustion are composed of heated gases; there is a natural tendency'fon them to rise. Inxsome cases, particularlywhen the-furnace: is being; fired at a lowrate, the-"gases-will tend to rise-quickly enough so that the work ex tending between the furnace-units is-not entirely covered; thus: resulting in uneven=heating-. At other times, when the furnaces-are being.- fired at capacity the-opposing blasts --of' these products trolled bya' dam-per 3W located in thesta'ck-l The dampen can be a'djusted' manually in the usual fashionby a handle 32 omits-shaft or, ifidsiie'di can be adjusted automaticallyin any conventional l manner in accordancewith-f urnace= pressure; Thismember 2 l=can be liftedintoand' out of place" in order to afibrd access to the convey ing rolls ll 'by'liftin'g lugs'tt that extend from the upper surface thereof 1 One. or i more ofthe members 21 extendingbetween the furnace units is provided with an opening 34- that" is aligned with the" work" pass ing betweenthe furnace units. In this opening thereis placed aradiation responsive-pyrometer 3 5 that can be" used to measure-- the temperature ofthe' work;

The bottom of the housing between the an na ce units is-- formed by a floor that comprises a' block of refractory-material 36 which'isb'a'cled up by suitable reinf'orcing metal 31: Thisb'lo'ck is supported by angle-irons 3 t that" exten'd" out-- wardly from the faces of thedurnace units. As

shown herein, theblock slopes downwardly at an angle to the horizontal so that any-scale or dirt which may fall from the work being heated can easily b'e'removed through the space between the lower surface of the left block 22 and the upper surface of. the floor 36. Since the opening between the fioor'and the lower surface of the left block 22 would. permit an inflow of air that would have a cooling effect upon the work, this opening is closed by a door 39 which rests upon an extension 4! of the reinforcement 31 of the floor. The upper end of the door can be received and held in place between the block 22 and one of the lugs 23, as is best shown in Figure 2 of the drawing. A handle 42 is provided by means of which this door can be removed for cleaning purposes when it is so desired.

The embodiment of the invention disclosed in Figure 3 is substantially the same as that described above. In this figure, however, the conveyor roller I la is shown as a single conveyor instead of a double conveyor so that only one billet at a time may be heated in the furnace.

In this embodiment of the invention the upper portion of the housing 2] is constructed of refractory material 43 backed up by metal work 44 as was the previously described embodiment. In this case, however, there are provided a plurality of openings 45 through which the exhaust gases from the furnace can pass into the atmosphere. Whether a single damper controlled opening of the type shown in Figure 2 is used, or whether a number of openings of the type shown in Figure 3 are used will depend entirely upon the requirements of a particular furnace installation. This is determined somewhat by the temperature to which the billets are to be heated and also upon the volume of combustion gases that are produced. It is noted that an opening similar to opening 34 may be provided for a pyrometer if such is necessary or desired.

The embodiment of the invention shown in Figure 4 has the lower portion of the housing formed in exactly the same fashion as the lower portion of the housing of the two previously described embodiments. The upper portion of the housing, however, is formed of a number of separate blocks of refractory material. As shown herein, there are provided side blocks 415 which rest upon the blocks 22 and which are guided into position by lugs 41 extending from each of the furnace units. These blocks may be lifted into and out of position by suitable rings 48 through which hoisting apparatus can be inserted. The top closure of the housing comprises a refractory plate 49 that rests upon the upper ends of the blocks 46. This plate has an opening in the center thereof in which is placed a stack 5| for the exhaust gases. Plate 49 is also provided with openings '52 on each side of the central opening forming the stack which openings are normally closed by plugs 53 of refractory material. In some cases it may be desirable or necessary to have a larger opening for the exhaust gases than is provided by the stack. In such a case the plugs 53 will be removed from the openings 52 and the gases can then exhaust through these openings. It is noted that the stack 5| may be provided with a damper, if desired, and one of the blocks 4=E may be provided with an opening to receive a pyrometer for measuring the work temperature.

From the above description it will be seen that the continuous furnace of the invention is made up of a plurality of independent and individual additional heat is placed in the work by the next furnace unit I. The use of the shields or housings between the furnace units insures that the work will at all times during the heating process be enveloped by products of combustion and that the heating process will be continuous.

While in accordance with the provisions of the Statutes, I have illustrated and described the best form of embodiment of my invention now known. to me it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from: the spirit and scope of the invention, as set forth. in the appended claims, and that in some cases certain features of my invention may be used: to advantage without a corresponding use of other features.

What is claimed is:

1. In a furnace system, the combination of a plurality of axially aligned furnace units each having a chamber and axially aligned entrance and exit openings, conveying means including a horizontally extending shaft having a portion thereof aligned with said openings extending between each pair of furnace units and operative to move work therethrough, and housing means between pairs of furnace units including a pair of side members, means to mount said members jointly on the ends of the units between which they extend with one of said members on each side of said openings and having a portion thereof below said shaft, a floor member extending between the lower ends of said side members to close the space therebetween, and a U-shaped shield removably mounted between the ends of said furnace units adjacent to the upper ends of said side members, said shield extending around the upper portion of said openings and being provided at its ends with means through which said shaft may pass and with'a vent opening in the upper portion thereof.

2. The combination of claim 1 in which one side of said floor member is lower than the other, and a normally closed door adjacent to the low portion thereof through which access may be had for cleaning said housing.

3. In a furnace system, the combination of a plurality of furnace units each having a chamber and axially aligned entrance and exit openings, conveying means between each pair of furnace units operable to move the work therethrough and including a horizontally extending shaft, and a housing between each pair of furnace units surrounding the exit opening of one and the entrance opening of the other including a side member of refractory material on each side of said openings having a portion thereof below said shaft and being supported jointly by the furnace units, a substantially u-shaped part having a refractory lining above said side members and surrounding the upper portion of said openings, means to support said part removably above said side members, and said housing also including a floor portion extending below said openings I References Cited in the file of this patent a d between said aide mer h'ers, sai d floor por- UNITED STATES PATENTS tlon havmg a refractory hmng, 581d U-shaped part being provided with an upwardly extending Number Name Date vent through which products of combustion dis- 5 1'9461'971 Harte! 13, 1934 charged from said. chambers may be exhausted 2,492,942 f 1943 2,540,966 swam Feb. 6, 1951 FREDERIC O. HESS.

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