US2669442A - Annealing apparatus - Google Patents

Description

Feb. 16, 1954 'J. E. ERHARDT, JR 2,669,442

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ANNEALING APPARATUS 6 Sheets-Sheet 3 1954 J. E. ERHARDT, JR 2,669,442

ANNEALING APPARATUS Filed Aug. 24, 1948 6 Sheets-Sheet 4 29 J51, 2 (Y o ,5? 2 6 I 6'1 so 94 By AA M l'l'oz'ne ys.

Feb. 16, 1954 J. E. ERHARDT, JR 2,669,442

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Patented Feb. 16, 1954 UNITED: STATES PATENT QFFI 2,669,442

ANNEAHN BAEATW John E. Erhardt, J12, Baltimore, Md, assignon to Crown Cork &' Seal Company, Inc.', Baltimore,

Md., a corporation of New York Appl cation augu t Seria his. 5d??- 21 Glaims.

The present inven i n re ate to a anne l ng appa a us, of the t pe ih whi h huq rip m tal s nnealed du in its co n us m ement hrough the. apparat s a dis ngui ed from. ba ch annea in fu ac s. n Whieh, ta k or rolls oi sheets or plates are annealed.

Mo e articularl th n en relates n a apparatus ior ann alin 2 o l t p e The invention includes numerous improvements upon m d fiqa iqh of, a di n to a e ing apparatus of the type shown in the prior patent of Cooper et al. No. 2,245,131, March 28, 134A, and in, pending applications of Cooper et al., serial Nos, 497,524, filed August 5, 1943, now Patent 252L011; and 565914;, filed November 24, 194 4, now Patent 2,478,964 respectively. The primary object oi the invention is to provide an apparatus which is capable of annealing strip steel having a high Rockwell number at an increased rate of production as compared with other continuous annealing machines, and to provide an apparatus which is capable of annealing strip steel having a lower Rockwell number than was possible with prior machines.

Another object of the invention is to provide a machine which is more flexible in operation, so that various annealing cycles may be followed, to produce different characteristics as to hard-v ness and ductility in the annealed product. To

this end, the invention provides an apparatus having an extended holding or soaking zone, which'may be adjusted as to time duration and temperature, to produce the desired effects on the strip steel.

Another object is to provide an annealing apparatus in which the heating zone is adjustable as to temperature and time duration, making it possible to employ various different heating pore tions in different annealing cycles. A further object of the invention is to provide an apparatus in which a certain portion or portions thereof may be used selectively as heating or holding sections, to vary the annealing cycle.

'Another object is to provide improved temperature controlling mean in the holding and cooling zones of the apparatus, including improved gas circulating and cooling devices.

Another object is to provide an apparatus in which access to the interior may be had more readily than has heretofore been possible.

Another object of the invention is to improve t un in 9f t st p gu d s t9 the end that they may run substantially free in posi tively cool bearings sealed in gas-tight relation f om the o ts e o t e apparatu Other and further objects and advantages will be apparent from a consideration of the follow-1 ing description of a preferred embodiment of the invention, shown for purposes of illustration in the accompanying drawings, in which Figure l is a side elevation of the annealing apparatus, with certain conventional strip hang dling mechanisms associated therewith;

Figure 2 is a diagrammatic plan View 91} Figure 1;

Figure 2a is an enlarged elevation of the Qqql: ing section, looking from the. opposite direction as compared to Figure 1;

Figure 3 is a transverse section substantially on line 3-3 of Figure 1;

Figure 4 is a fragmentary, somewhat diagram: matic, longitudinal section throu h th and holding sections of the apparatus 2 tain parts omitted;

E e re 4a s a irasmeh arr set les eh enlarged scale 011 .11.16 l-r le, Fi l 5 .5

F ur 4b is a simi r ee eh she 4 2:5? of Figure 4;

i ure do is a s milar sect ee eh ta i? of Figure 4;

Figure 5 n, enlar ed lee iihsiihhl ems, ith, a re tal n a bro en a shewihs the interi r of he first heat is s et hhsa Figure 6 is has. hhsthht sllr in fiat qt h;

Fi ure 7 is se mented, seeti hel he e ee re of o e cf the removable arise. wi hin ure 8 i Pi92 nd. eaiha e evate sh a ferr d rhl and r ll sush he me hani m;

Figure 9 is an elevation taken from the right o; ishes and Fi u e 10 t? a im)? sub tan all 91. 11

ure 8.

hss h 9 his penn ng to Fi u e 1, th whee in ap aratus. e r se t d en al 5 inc u s "h atin .6 a h lding: scales se hh and (299 as se ti n 1' ent-hi is i lse i e m l hhve the floor it be ween ited. as o f e t p hand i devi e el i as including at the i iee end a h r of sell hwinders H and It, a welder It for attaching the trailing end of one strip to the leadin end 9f another strip and a looper l4, providing an excess supply of strip which may be delivered continuously to the annealing apparatus during the time that the delivery of strip from the unwinder is arrested, while the tail end of one strip being welded to the leading end of the nextf At the de ive e d, h stri he sihhs de i es san a discharge looper l and a coiler H3 and a shear, not shown. Since these instrumentalities are described more in detail in the above identified patent and applications, and are well-known in the practical art, they need not be further described.

The annealing apparatus is supported above the mill fioor 9, and preferably above a pit therein, by a structural steel framework including a plurality of pairs of spaced uprights 2|, 22, 23, 24, upper and lower longitudinally extending members 25, 26, and 21, and a plurality of transverse members 28, spaced apart at suitable distances. The heating and holding sections 6 and i of the apparatus, as hereinafter described, are enclosed within a sheet metal shell 29, which includes longitudinally extending front and back sections and appropriate end portions. Also, the shell includes longitudinally extending bottom walls below the front and back walls and fixed transverse bottom sections 3|, spaced apart longitudinally and between which removable bottoms are positioned as explained below.

The space within the shell is lined with relatively thick, heavy refractory brickwork providing longitudinally extending, vertically disposed, parallel front and back walls 32, 33, end walls 34 and 35 and a plurality of transverse walls. As shown in Figures 4 and 5, the transverse walls in the heating section, at the left, are arranged in two groups, with the individual walls of the groups alternating with each other, the first group including walls 36, 31 and 38, extending from the fixed bottom wall sections 39, upwardly, but terminating short of the upper edges of the longitudinal walls. The other group consisting of transverse walls 40, 4| and 42 extend upwardly to fixed top walled sections 43 and downwardly toward the bottom, but in spaced relation thereto, the lower ends of the walls being of arched form as indicated at 44 (Figure 4a) supported from the longitudinal walls.

The several walls just described define a plurality of vertically extending, heating chambers 45, 46, 41, 48, 49 and 50 through which the strip is trained successively in a serpentine path, upwardly through the first chamber, downwardly through the next, and so on. In the spaces above the first group of transverse walls 36-38, pairs of strip guide rolls 5| and 52 are mounted, to guide the strip from one chamber to the next. Similarly, below the other group of transverse walls -42, pairs of guide rolls 53 and 54 are mounted, under which the strip passes from one chamber to the next.

Below the first heating chamber is a remov- -able bottom wall section 55, having a relatively narrow slot 56 therein through which the strip jenters the chamber. The removable bottom section includes a shell plate 3| of the type previously mentioned, supported by a rectangular,

channel member frame 51, carried by longitudinally extending channels 58 having their ends bolted to the lower surfaces of channel brackets '59 carried by the transverse frame members 28.

A gas-tight roll seal 60 of the type shown and described in the above mentioned patent and applications is suspended below the slot 56 to prevent the entrance of external air into the chamber. The strip is delivered to the gas-tight seal by an external guide roll 6|, which receives the strip from the infeed looper I4.

The upper ends of the pairs of heating cham- .-bers on'opposite sides of walls 36, 31, and 38 are closed by removable hoods or covers 55, 66, 61

of substantially identical construction as best shown in Figures 3 and 5. Each hood includes a metallic shell having a transversely arched top 68, vertical side and end walls 69 and 10, and an inturned bottom section 1|, extending completely around the margin thereof. The interior of the shell is lined with refractory brickwork 12 of arched form and including vertically disposed end and side wall portions.

The shell end and side walls 69 and 10 are bounded by an outwardly facing channel 13, to which a depending flange i4 is secured, with its lower portion extending downwardly into a continuous channel 15, carried by the main furnace shell 29 and extending entirely around each hood. The several channels are filled with a suitable liquid, such as water, thereby providing, in cooperation with the flanges 74, a gas-tight liquid seal for the removal of the covers.

The lower ends of the pairs of heating chambers on opposite sides of the other group of transverse walls 40, 4| and 42 are closed by removable bottoms, a typical one of which is shown in Figures 5, 6 and '7. These bottoms include lower shell plates 3| upon each of which is mounted a relatively thick body of brickwork 80. The plates are mounted upon the upper webs of channel members 8| constituting a rectangular supporting frame, disposed, in turn, upon longitudinally extending channel members 82, having their ends bolted to the lower surfaces of channel brackets 83, projecting longitudinally from the transverse I-beams 28 and secured in place by vertical webs 84. Except for the matters of dimension, all of the removable bottom sections and their supporting structures, including the section 55, may be identical.

The rectangular supporting frame 8| has on its exterior surface a marginal trough which may be filled with a sealing liquid, such as water, and into which a continuous flange 85 projects, the latter being carried by the fixed bottom wall sections 30 and 31 of the furnace shell, thereby providing a gas-tight liquid seal, preventing the admission of atmospheric air or the escape of the non-oxidizing gas between the removable bottom sections and the adjacent fixed furnace walls.

Access to the interior of the heating sections may be had by lifting the upper covers; for instance, by an overhead crane 88 (Figures 1 and 3) and by dropping the lower, removable bottom sections, by the use of suitable jacks, not shown, after the securing bolts have been released.

The end walls of the heating section and the transverse walls therein carry a plurality of refractory hangers 90 and guides or spacers 9| for radiant electric heating strips 92, which may be arranged as shown diagrammatically in Figure 6 so as to produce an even distribution of heat through the width of the strip steel and to prevent overheating of the edges thereof.

The control circuits for the several heating elements are so arranged that the ones in the last heating chamber 56 may be die-energized at will, leaving only the first five heating chambers in operation, and converting the sixth chamber 50 into a cooling chamber or first holding chamber in the holding zone, to prolong the holding portion of the annealing cycle. Since any appropriate control circuit may be employed, to render the elements in the final heating chamber selectively operable or inoperable, a circuit diagram is thought to be unnecessary.

As is well understood in this art, the entire interior of the annealing apparatus is filled with a non-oxidizing gas, to prevent oxidation of the strip at the high temperatures to which it is raised. In accordance with the present invention, the heating, holding and cooling-sections of the apparatus are independently supplied with a non-oxidizing gas such as a mixture of carbon dioxide and carbon monoxide in some cases nitrogen. Preferably, the gas is delivered to the heating zone at the lower end of the final heating chamber 55!, as indicated at Q5 Figure 4 thereby exerting a cooling effect on the strip, when that chamber is used as cooling or hoiding chamber, with the heating elements deenergized. The gas flows slowly through the chambers 5t-55 in a direction opposite to the movement of the strip and leaks outwardly through the roll seal lit, at the bottom or the entrance chamber it.

The various strip guiding rolls may all be of substantially the construction shown in Figures 8-l0 and may all be mounted in substantially the same way. The furnace shell 29 and the adjacent refractory wall is are provided with circular openings rimmed by an annular channel fitting 9t, welded to the outer surface of the shell. A closure casting 9! includes a cylindrical body 98 extending into the above mentioned openings and an apertured plate 953 having its margins bolted to the channel fitting The central aperture I 80 in plate as communicates with a bearing receptacle till, defined by an axially prolooting, cylindrical wall I Surrounding the bearing receptacle is an annular chamber I53 for a cooling fluid. formed by an outer circumferential wall section its and an end wall its.

The bearing receptacle Iti is closed by a cap I06 bolted to the end Wall I55, with a suitable gasket interposed. Cooling liquid may be delivered to the chamber I hit by a pipe it)? leading from any suitable source of supply, through the circumferential wall tilt, and the liquid may be discharged from the chamber through a pipe Hi8 extending through the marginal flange of cap 106 and the end wail let. The burner I94 causes the Water to circulate around the bearing in the direction of the arrows.

The roll 53 preferably has tapering ends, one of which is shown at Ills, terminating in a journal III], extending through the opening iii?! in plate 99 and received in a roller bearing assembly III mounted in the bearing receptacle NH. The bearing may be supplied with lubricant by a pipe H2 extending from a nipple I I3 through the outer circumferential wall Hit, the inner wall Hi2 and the cage H t of the bearing assembly. Prefl erably, the nipple H3 is enclosed by a cap I I5, threaded upon a suitable collar IIB associated with the outer wall Iil l.

It should be understood that the supporting structure at the opposite ends or each roll may be identical to that shown in Figures 8-10. Each closure casting 91 may be filled with a suitable refractory insulating material II'I, having a tapering inner surface, spaced fairly closely to the tapering end I09 of the roll to minimize heat losses. The several cooling chambers I03 may be supplied with cooling liquid from a common source by any suitable piping system, not shown, and the discharge pipes Hi3 may be similarly interconnected, for common disposal of the cooling liquid, or for re-circulation through a heat exchanger to the chambers.

The holding zone of the apparatus in accordance with the present invention consists of a plu- 6 rality of groups of vertically disposed, parallel chambers through which the strip is successively trained for movement. In the present instance, there are four groups, each including live interconnected chambers or passes, the first and last of which are of greater transverse dimension in horizontal section longitudinally of the apparatus, than the intermediate three chambers. As shown in Figure 4, the first group of chambers I 28 in the holding zone comprises a first relatively wide chamber I2I, defined at one end by the transverse wall 42 and at the other by the first of a pair of walls I23 and HM, which extend from the bottom upwardly toward, but spaced r from the top wall or the upper edges of th longi-- tudinal walls. The three intermediate chambers #25, I26 and E27, of less horizontal longitudinal dimension are defined by the said walls. I23 and 24 and by another pair of walls I23 and I29 which extend from the top of the apparatus downwardly toward, but terminating in spaced relation to, the bottom thereof. Th final chamber I30 of the first group 2 3 is of the same size as the first chamber 2I and is defined by the wall lit and a relatively thick wall I3I, separating the first group of chambers from the next group.

Above walls I23 and iii and below walls I28 and I29 are single guide rolls I32 and I33, about which the strip trained for passage through the chambers. Pairs of rolls are employed for transferring the strip around the ends of the relatively thick walls 42 and, l'sI, etc, constituting the division Walls between the successive groups of the chambers in the holding zone.

The upper ends of the several groups of chamhers in the holding zone are closed by removable covers I35, 35, I31, and I38, while the bottoms are closed by removable bottom closure members I39, Mil, MI, and. I42, the construction of which may be similar to the corresponding elements previously described except that the covers I35, etc, need not be of arch form, but may be substantially fiat as shown in Figures 4 and 4c, and comprised of a metal shell I53 and a refractory lining IM. The liquid seal arrangements may be substantially as previously described.

The several chambers in the holding zone are all filled with an atmosphere of a non-oxidizing gas of the type previously referred to. This gas is continuously circulated through the several chambers successively in a direction opposite to that of the movement of the strip through the chambers. Moreover, the gas after traveling through the chambers is withdrawn by suitable gas circulating means, through an external conduit, and returned to the last chamber of the holding zone for re-circulation therethrough. The heat picked up from the strip by the circulating gas is withdrawn therefrom during this return passage by one or more suitable heat exchangers.

Referring to Figures 1, 2, and 4, a blower I50 delivers the non-oxidizing gas through a discharge conduit IEI into the last chamber I30 of the last group of chambers in the holding zone, through an opening I52 in the front wall thereof. The gas, after flowing through the chambers successively and absorbing heat from the strip is withdrawn through an opening I53 in the front wall of chamber iZI, at whichpoint it passes through a heat exchanger I54, which may be of the well-known. "water cooled type. From the heat exchanger, the cooled gas flows through conduit I55 to the intake of the blower I5 0, from which point the cycle is repeated. Interposed in the conduit I55, ahead of the fan I50, is a gate valve or damper I56, which is manually adjustable, to control the volume of flow of the gas and, hence, the amount of heat extracted from the strip steel, so that the holding portion of the annealing cycle may be varied at will and accurately controlled.

Although in the embodiment shown in the accompanying drawings, the gas circulating devices are positioned adjacent the top of the holding zone chambers, it should be understood that they may be positioned near the bottom thereof, or elsewhere, as desired.

, Referring to Figure 1, it will be noted that an upper, supplemental framework I58 extends 1ongitudinally toward the right and is supported by the uprights 23 and 24 and by another pair I59 constituting a part of the discharge looper I5. The framework I58 supports a generally rectangular, horizontally elongated casing I60, while a similar lower casing IGI is appropriately supported therebelow, in fixed position by the uprights 23 and 24. The casings are provided with a plurality of pairs of aligned openings in their front and back walls, in which closure members 61 are positioned, as previously described, to support strip guiding roll in the casings. The upper casing I60 has a plurality of spaced openings in its bottom wall, to the margins of which a plurality of downwardly extending metallic chute sections I62 are secured. These sections are suspended from the upper casing I60, with their lower ends terminating in spaced relation above the lower casing, in alignment with openings in the top wall of the latter.

The lower ends of the chute sections are connected to the lower casing IBI by flexible sections I62, which preferably take the form of Sylphon bellows of thin, flexible, sheet metal, sealed in gas-tight relation, respectively, to the chute sections and the casing and establishing communication therebetween. Thus, the cooling chutes, suspended from above, are free to expand and contract under the influence of temperature changes, the movement being permitted by the contraction and expansion of the bellows sections.

The lower casing I6I has its entrance end in communication with the discharge opening I63 (Figure 4) of the last holding zone section I30. The strip is trained about the first roll in the casing I6I and passes upwardly through the first cooling chute I62 to the first roll in the casing I60 over which it is trained for movement downwardly through the next cooling chute. It should be noted that the second, third, fourth, fifth, and

sixth cooling chutes are relatively wide, longitudinally of the apparatus, while the first and seventh are relatively narrow. At the bottom of the second chute, the strip is trained about the second roll in casing I6I for movement upwardly through the same or second chute. At the upper end of the latter, the upwardly traveling strip passes over the second roll in casing I6 for downward movement in the third chute and so on. In other words, the rolls in the lower casing I60 guide the strip back upwardly through the same cooling chamber in which it descended,

while the rolls in the upper casing I60 transfer the strip from one cooling chute to the next.

After passing downwardly through the last cooling chute, the strip is delivered, through any appropriate gas-tight seal mechanism for movement upwardly over an upper guide roll I55, from which point it travels downwardly under a guide roll I66, to the infeed rolls I61 of the delivery looper I5. As shown somewhat diagrammatically in Figure 1, the seal at the delivery end of the cooling section may comprise a Water filled quench tank I10, into the open upper end of which a casing extension or delivery chute I1I projects, below the surface of the water. The strip passes below a guide roll I12 in the tank and then through a pair of wringer rolls I13 which remove excess surface water prior to its engagement with roll I65.

The interiors of the cooling chambers and of the upper and lower casings are filled with a nonoxidizing gas as previously described. This gas is circulated quite rapidly through the cooling chambers in a direction opposite to the direction of movement of the strip, preferably along two independent paths for two groups of sections, to facilitate the extraction of heat from the strip, by the use of two heat exchangers of high capacity. A first blower I15 delivers gas to the last cooling chute through a conduit I16, and this gas is withdrawn from the fourth cooling chute, at a point spaced from the upper end thereof, by a conduit I11, delivering to a heat exchanger H8, which, in turn, delivers the cooled gas to the intake of the blower W6. A second blower I18 delivers a stream'of gas on another path through a conduit I to the upper end of the fourth cooling chute, at a point just above the conduit I11 which withdraws heated gas for delivery to the first heat exchanger. The gas passes from conduit I80 through the cooling chutes to the upper end of the first chute, from which point it is withdrawn by a conduit I8I for delivery to a second heat exchanger I82, the latter being in communication with the intake of blower I16. Hence, the strip is cooled by contact successively with two independent streams of positively cooled gas, flowing counter to the direction of movement of the strip. In this manner, the strip, although moving at a high rate of speed, may be quickly cooled below the oxidizing temperature for delivery through the quench tank to external atmosphere. Gate valves or dampers may be interposed in the gas circulating systems for the cooling section, or variable control may be effected by changing the speed of the blowers. However, since it is usually desired to cool the strip quite rapidly, after it leaves the holding zone, such adjustments are not often required.

It is through that the operation of the apparatus in accordance with the present invention will be understood from the foregoing description. All of the various chambers in the heating, holding and cooling zones are filled with a nonoxidizing gas, delivered through the opening or openings 95, adjacent the lower end of the sixth heating chamber, 50. The heating elements 92 are energized and the strip moving rapidly through the apparatus is quickly heated, primarily by radiation from the elements and from the adjacent refractory walls. The strip is raised to a temperature of ISO-3 F. or above in the heating zone. If it is desired to produce relatively high Rockwell steel, all six heating chambers are used to heat the steel and the speed of travel of the strip is raised, to increase the production rate. However, if lower, Rockwell steel strip is to be produced, the speed is reduced and the sixth chamber is used for dropping the temperature from 1800 F. to substantially 1300 F., by deenergizing the heating elements in that chamber. The delivery of the non-oxidizing gas to the lower end of this sixth chamber assists in-reducing the temperature of the strip when so desired.

The temperature of the strip in the holding zone is accurately controlled and reduced gradually, in accordance with the particular annealing cycle being followed. The refractory, insulated walls between the successive passes in this zone prevents too rapid a drop in the temperature. The counter-current circulation of gas in the successive passes, with the control of the gas temperature and volume of flow, effected by the heat exchanger [54 and the valve 156 makes it possible to accurately control the holding portion of the annealing cycle. As a result of the construction described, it is possible to elfect a relatively slow drop in temperature in the initial portion of the holding zone and a more rapid drop as the strip approaches the discharge end thereof.

In the cooling zone, the strip is still more quickly reduced in temperature, to a point where it will not be oxidized on exposure to external atmosphere.

The invention is not limited to the details of construction shown in the accompanying drawings and described above, but covers all modifications coming within the appended claims and their equivalents.

I claim:

1. An apparatus for annealing strip steel com prising a plurality of elongated, parallel chambers in endwise communication with each other, means for substantially sealing the chambers from external atmosphere, means for guiding continuous: strip through the chambers successively, means in a first group of chambers, constituting a heating zone, for heating the strip to, annealing temperature, means for introducing a non-oxidizing gas into the last chamber of said group adjacent the exit end thereof, means for selectively controlling the heating means in the last mentioned chamber, whereby it may be selectively converted from a heating chamber to a holding chamber to shorten the heating portion of the annealing cycle by rendering said heating means inoperative therein, means independent of the aforesaid gas introducing means for circulating a non-oxidizing gas through a second group of chambers, constituting a holding zone, in a direction opposite to that of the strip movement, and means independent of the aforementioned gas introducing means and gas circulating means for circulating an independent stream of non-oxidizing gas through a third and final group of chambers, constituting a cooling zone, in a direction opposite to that of the strip movement.

2. An apparatus in accordance with claim 1 in which the first-mentioned gas circulating means includes an inlet in the last chamber of the group constituting the holding zone, an outlet in the first chamber of said group, an external conduit connecting the inlet and the outlet, zgas circulating means in said conduit and a variable heat exchanger in the conduit for extracting variable amounts of heat from the gas circulated therethrough.

3. An apparatus in accordance with claim 1 in which the means for circulating the gasthroughthe third group of chambers includes an external conduit connected to the interior of spaced apart chambers, gas circulating means insaid conduit and a heat exchanger .for extracting heat from the gas in the conduit,

4. An apparatus for annealing strip steel comprising a heating section having front and back longitudinal walls and a plurality of parallel transverse walls dividing the space therein into a plurality of vertically disposed parallel, elongated chambers, alternate transverse walls extending upwardly from the bottoms of the chambers terminating short of the tops of the longitudinal walls, a pair of guide rolls above the upper ends of said alternate transverse walls for guiding strip steel thereover, the other alternate transverse walls extending downwardly from the tops of the chambers and terminating short of the bottoms of the longitudinal walls, and a second pair of guide rolls below the lower ends of said other alternate transverse walls for guiding the strip therebelow.

5. An apparatus for annealing strip steel comprising a heating section having front and back longitudinal walls and a plurality of parallel transverse walls dividing the space therein into a plurality of vertically disposed parallel, elongated chambers, alternate transverse walls terminating short of the tops of the longitudinal walls, a pair of guide rolls above the upper ends of said alternate transverse walls for guiding strip steel thereover, the other alternate transverse walls terminating short of the bottoms of the longitudinal walls, and a second pair of guide rolls below the lower ends of said other alternate transverse walls for guiding the strip therebelow, removable covers above the first mentioned pairs of rolls and removable, horizontally extending, bottom closures below the second mentioned pairs of rolls, substantially coextensive in area with the chambers thereabove.

6. An apparatus for annealing strip steel con prising substantially continuous longitudinally extending front and back walls, means at the upper and lower ends thereof providing top and bottom walls a plurality of vertically disposed transverse walls dividing the space between the longitudinal walls into a plurality of elongated parallel heating chambers, the first transverse wall being imperforate from the top of the bottom wall and constituting an end wall, the second transverse wall and the succeeding alternate walls extending upwardly from contact with the bottom Wall and terminating at their upper ends below the top Wall, the third; and other alternate transverse wall extending downwardly from contact with the top wall and terminating at their lower ends above the bottom wall, and roll means above and below the two sets of alternate transverse walls for guiding strip steel in a serpentine path successively through the chambers.

7. Apparatus for annealing strip steel, comprising vertically disposed, parallel, horizontally and vertically elongated, substantially continuous longitudinal front and back walls, end walls closing the end spaces therebetween, a plurality of removable covers supported by the longitudinai walls constituting a sectional top wall, a bottom wall comprising a plurality of fixed sections and a plurality of removable sections alterhating therewith, and a plurality or" vertically extending, parallel transverse walls dividing the interior of the apparatus into a plurality of vertically elongated parallel chambers, said transverse walls consisting of a first alternate series terminating at their upper ends in spaced relation below the covers and at their lower ends in contact with the fixed sections of the bottom wall, and a second alternate series having their lower ends spaced above the removable sections of the bottom wall and their upper ends in contact with said removable covers, and roll means above and below the first and second series of transverse walls respectively for guiding the strip in a serpentine path successively through the chambers.

8. Apparatus for annealing strip steel, comprising vertically disposed, parallel, horizontally and vertically elongated, substantially continuous longitudinal front and back walls, end Walls closing the end spaces therebetween, a plurality of removable covers supported by the longitudinal walls constituting a sectional top wall, a bottom wall comprising a plurality of fixed sec" tions and a plurality of removable sections alternating therewith and of greater longitudinal dimension than the fixed sections, and a plurality of vertically extending, parallel transverse walls dividing the interior oi": the apparatus into a plurality of vertically elongated parallel chambers, said transverse walls consisting of a first alternate series terminating in spaced relation below the covers and a second alternate series having their lower ends spaced above the removable section of the bottom wall, and roll means above and below the first and second series of transverse walls respectively for guiding the strip in a serpentine path successively through the charm bers, each chamber of a first group of chambers being of relatively greater horizontal section and constituting a heating zone and each chamber of a second group of chambers being of lesser horizontal section and constituting a holding zone.

9. An apparatus in accordance with claim 8, characterized in that, in said heating zone pairs of rollers are disposed above and below the successive transverse walls to guide the strip from one chamber to the next.

101. Apparatus in accordance with claim 8, characterized in that single guide rolls are journalled above and below a plurality of successive transverse walls in the holding zone to guide the strip successively through the chambers thereof.

11. An apparatus in accordance with claim 8, characterized in that the holding zone is divided into a plurality of groups of chambers, each group comprising three chambers of small horizontal section and entering and exit chambers of greater section and in that single rolls guide the strip into and out of the chambers.

12. An apparatus in accordance with claim 8, characterized in that the chambers in the holding zone are arranged in a plurality of groups and in that an independent removable cover closes the chambers of each group.

13. An apparatus in accordance with claim 12, characterized in that an independent removable bottom wall section closes the lower ends of the chambers of each group in the holding zone.

14. An apparatus for annealing strip steel, comprising vertically disposed parallel horizontally and vertically elongated front and back longitudinal walls, a plurality of transverse walls dividing the space therebetween into a plurality of vertically elongated parallel heating chambers, a plurality of removable covers supported by the longitudinal walls and by alternate transverse Walls, each substantially coextensive in area with and closing the upper ends of a pair of chambers therebelow, a plurality of removable bottom closure members, each substantially coextensive in area with and closing a pair ofchambers thereabove, roll means below the covers for iii . l2 guiding the stri from one chamber to the next, and roll means above the removable bottom closures for guiding the strip from one chamber to the next.

15. An apparatus for annealing strip steel comprising substantially continuous longitudinally extending front and back walls, a bottom wall including alternate, fixed and removable sections, a top wall and a plurality of vertically disposed transverse walls dividing the interior space into a plurality of elongated parallel chambers, said transverse walls being arranged in two groups alternating with each other, a first group comprising individual walls each terminating at its lower end in an arch structure, spaced above the removable bottom wall sections and supported from the longitudinal walls, the other group comprising individual walls each extending upwardly from the fixed bottom wall sections and terminating in spaced relation below the top wall.

16. Means for supporting a strip guiding roll in a continuous annealing apparatus having a side wall provided with an opening through which the roll may pass, and an annular supporting fitting surrounding said opening and secured to the exterior surface of said wall, said means come prising a closure for the opening having 8. cylindrical body projecting through the furnace side wall along the margins of the opening, an apertured face plate at the outer end of said body, operatively secured to and supported by said fitting, means carried by the plate defining a bearing socket communicating with the aperture in the plate, means defining an annular cooling chamber surrounding the socket, a bearing in the socket for the roll journal, a cap for closing the outer end of the socket, and means for circulating cooling fluid through said chamber.

17. An appealing apparatus for strip steel comprising a supporting framework including a plurality of uprights and longitudinally and transversely extending lower members supported thereby, brickwork carried by said members defining a plurality of parallel vertically extending chambers through which the strip is trained for movement, and a plurality of removable bottom sections, each comprising longitudinal and transverse framing elements, refractory material supported thereby and means removably connecting said elements to certain of said lower members, whereby said sections may be lowered for access to said chambers.

18. An annealing apparatus comprising asupporting framework including a plurality of uprights and a plurality of longitudinally and transversely extending lower members supported thereby at points spaced well above the lower ends thereof, refractory walls carried by said members defining a plurality of parallel vertical chambers through which the strip is successively trained for movement, and a plurality of removable bottom sections closing the lower ends of the chambers, certain of said sections being of a size to close at least two adjacent chambers and comprising transversely projecting framing elements removably connected to certain of said lower members, whereby said sections may be lowered to give access to the chambers thereabove.

19. An annealing apparatus for strip steel comprising a supporting framework includinga plurality of uprights and longitudinally and transversely extending lower members supported thereby in spaced relation abovethe lower ends thereof, refractory walls carried by said members defining a plurality of parallel vertically extending chambers through which the strip is trained for movement, a plurality of removable bottom sections and means for supporting the same from the transverse members, said means comprising brackets projecting longitudinally from the transverse members, longitudinally extending channels below the sections and releasable means for securing said channels to the undersurfaces of the brackets, whereby the bottoms and the channels may be lowered to give access to the chambers.

20. An annealing apparatus for strip steel comprising fixed refractory wall members defining a plurality of parallel vertically extending chambers through which the strip is trained for movement, a plurality of fixed bottom members, a plurality of removable bottom sections, and means for sealing the space therebetween, said means comprising an upwardly opening channel carried by each removable section around the perimeter thereof, a continuous, fixed depending flange carried by certain of said members, projecting downwardly into and extending continuously around the channel, and a body of liquid in the channel in sealing contact with the flange.

21. An annealing apparatus for strip steel comprising a pair of fixed, elongated, parallel, vertical, longitudinally extending, refractory walls and a plurality of fixed, parallel, transverse refractory walls defining a plurality of parallel vertically extending chambers through which the strip is trained for movement, a plurality of fixed bottom walls and a plurality of removable bottom sections disposed between certain of the said walls, and means for sealing the space around the perimeter of each removable section, each of said means comprising an upwardly opening channel suspended below the level of each section in substantial alignment with and below the perimeter thereof, a continuous depending flange carried by the adjacent fixed walls in gas-tight relation with respect thereto, projecting downwardly into and extending continuously around the channel, and a body of liquid in the channel in sealing contact with the flange.

JOHN E. ERHARDT, JR.

References Cited in the file of this: patent UNITED STATES PATENTS Number Name Date 1,727,192 Bailey Sept. 3, 1929 1,765,955 Von Maltitz et a1. June 24, 1930 1,811,522 Shover et al June 23, 1931 1,834,207 Fahrenwald Dec. 1, 1931 1,840,661 Fahrenwald Jan. 12, 1932 1,844,658 Holcomb Feb. 9, 1932 2,129,670 Brunner Sept. 13, 1938 2,175,233 Vaughan Oct. 10, 1939 2,222,362 Cerf Nov. 19, 1940 2,279,511 Gottignies et al. Apr. 14, 1942 2,345,181 Cooper et a1. Mar. 28, 1944 2,375,317 Moore et al. May 8, 1945 2,441,500 Miess May 11, 1948 2,491,828 Otis Dec. 20, 1949 2,521,044 Cooper Sept. 5, 1950 2,585,277 Seabold Feb. 12, 1952 FOREIGN PATENTS Number Country Date 557,029 Great Britain Nov, 2, 1942 OTHER REFERENCES Electro-Heating article, pages 69, 70, 71 and 72 of Iron and Steel Engineer, August 1948 (paper of AISE Convention of September 23, 1947).

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