US3374997A - Annealing cover - Google Patents

Description

March 1968 c. E. STUTENROTH ETAL 3,374,997

ANNEALING COVER v Filed May 15, 196E 2 Sheets-Sheet 1 Fig. 1

, INVENTORS CHARLES E$TUTENROTH AND Ham/2 A. WE/eTz,

ATTORNEYS.

March 26, 1968 c. E. STUTENROTH ETAL 3,374,997

ANNEALING COVER Filed May 15, 1965 2 Sheets-Sheet 2 INVENTORS CHAELES E SruTsugom AND BY Ham/ea A. WEETZ,

ATTORNEYS.

United States Patent 3,374,997 ANNEALING COVER Charles E. Stutenroth, Middletown, and Richard A. Wertz, Franklin, Ohio, assignors to Armco Steel orporation, Middletown, Ohio, a corporation of Ohio Filed'M-ay 13, 1-965, Ser. No. 455,554 3 Claims. (Cl. 263-49) ABSTRACT OF THE DISCLOSURE An inner cover which is placed over coils during box annealing in a single stack annealing furnace. The cover is cylindrical, vertically disposed and has helical corrugations to strengthen it. It is manufactured by corrugating stainless steel strip, continuously winding said strip helically, and joining the seams tightly together.

This invention resides in the provision of an improved annealing cover, more specifically an annealing cover with built-in helical corrugations and preferably manufactured from sheet metal comprising relatively light gauge stainless steel strip.

The general class of item to which this invention is directed is the inner cover which is placed over coils during box annealing in a single stack annealing furnace. The inner cover should be gas tight so that it may contain the coils in a protective atmosphere of some type. The outer cover, which ordinarily is the furnace itself, is placed over the inner cover and fired so that the coils are heated in a muflle. These inner covers are subject to mechanical damage as well as severe thermal shock.

Numerous annealingcovers havebeen used in the past. Structures prior to that of the instant invention have been welded from uncorrugated one quarter inch plates in many instances. Not only are such prior structures quite heavy but also they are subject to undue distortion occasioned by heating and cooling, particularly in those instances wherein the inner covers have been made from material from mixed heats.

Some of the prior annealing-covers have been provided with either vertically or circumferentially disposed ribs or stitfeners in an effort to make the covers stronger. Those covers which have been providedwith vertical ribs have not been resistant to bulging upon repeatedheating l and so have had to be braced with structuralrings and the like welded around the outside of the covers. These rings break off in service and are not'-eifective..Covers having the vertical ribs have a tendency to. bulge outwardly at the bottom during heating. Covers with circumferential ribs have a tendency to sag when heated to maximum temperature. All of the prior covers were fabricated from numerous pieces and shapes of steel which were welded together to make the cover and the ribs were usually externally applied, separate elements. Different section thicknesses and chemistries gave rise to different rates of thermal expansion and the resulting stresses often caused failures of the cover.

Accordingly, an important object of this invention is to provide an improved annealing cover having greatly increased strength to resist bulging while at the same time permitting lighter section thicknesses to be used.

A specific object of the invention is to provide an annealing cover comprising a cylindrical shell of sheet metal having helical corrugations therein.

It is an object of this invention to provide an annealing cover design which results in a remarkable reduction in material costs over the prior art designs.

A further object of the invention is to provide an annealing cover which is lighter in weight and easier to handle than prior art designs.

A further. object of theinvention is to provide anannealing cover which isnot subjectto undue distortion on heating and cooling.

Still another object: of the invention is to provide an annealing cover which hasv added resistance to mechanical damage from collisions with other equipment, rough handling and the like- Another object of the invention is to provide an annealing cover so designed that it maybe provided with a lid and lifting ring arranged so as to eliminatethe need for hooks or any other hardware on the side of. the cover and which will insure that the cover remains. vertically disposed when it: ismoved from .placeto place.

More specifically. it is. an object of this invention to provide an annealing cover manufactured fromv sheet metal comprising relatively light gauge stainlessv steel strip havingcontinuous.helical. corrugations formed there- .111.

These and other objects, of the invention. will become apparent to those skilled. in the art from the description to follow and withreference to the accompanying drawi'ngs, also keeping the foregoing remarks in. mind, and in which drawings like numerals are employed. to designate like parts throughout, and in which:

FIGURE 1 is a side elevation, withparts broken away and parts, shown in section, ofthe improved annealing cover of this invention,

FIGURE 2 is a top plan view of the annealing cover of this invention, and

FIGURE 3 is a sectional view of a furnace containing a vertical stack of'threecoils to be annealed, the inner annealing cover of this invention being diagrammatically shown in dotdash lines.

Broadly stated, the improved annealing cover of this invention is provided with what may be termed builtin, helical corrugations. The cover is preferably made of stainless steel and of sufficient gauge that it will resist the corrosive and mechanical abuse to which it will be subjected. Other materials such as ceramic or metallic coated steels could be used so long as they are resistant to oxidation at temperatures up to about 1600 F. Briefly stated, the generally cylindrical annealing cover of this invention is formed from stainless steel by corrugating strip, continuously winding said strip. helically, and locking the seams down tight mechanically. Lidsandother hardware are then welded onto the helically corrugated shells. The seamsmay also ,be welded, either'by hand or automatically, asthey areformedon the helical corrugating machine or afterward.

It is important to notethat this. invention. is directed to an annealing cover having corrugations which are not only helical but also which are built-in; this is clearly to be distinguished from all arrangements including separately formed ribs or stitieners fastened to the cover body either externally or internally thereof by mechanical means.

Referring now to the drawings, the improved annealing cover of this invention is indicated at 10 and is shown as provided with the helical corrugations 11. The lock seams are generally indicated at 12 and, as above noted, it is preferred that these be welded as they are formed. Preferably a conical lid 13 having a lifting ring 14 thereon is welded to the top of the cover 10. This lid-ring arrangement insures that the cover will remain vertically disposed when it is moved from place to place. This is important in view of the light gauge material from which the cover is made; if the cover were set down at an angle it could be damaged.

In forming the improved annealing cover of this invention a strip of suitable metal, generally in the range of 8 to 14 gauge, preferably stainless steel of about eleven or twelve gauge, is provided with longitudinal corrugations and one side of the strip is provided with an L-shaped flan-ge while the other side is provided with a U-shaped bead. The strip is formed so as to cause the strip to form helical convolutions in such manner that as the helical convolutions meet, the L-shaped flange is caused'to enter the U-shaped bead to form a lock seam. The seam is completed by pressing the head on the flange, laying the flange and bead down against the helical cover and pref erably welding the seam throughout, although it may be possible to employ short tack welds spaced along the seam if the seam is gas tight as formed.

It will be apparent that the corrugations imparted to the strip longitudinally thereof will, when the strip is formed by helical convolutions into cylindrical form, be disposed helically of the cover.

The lid indicated at 13 in the drawings is conical or dome shaped and has the lifting ring 14 thereon. This ring 14 is supported by three vertical fins 15 extending from and welded onto the conical lid 13', the ring 14 may be welded to these fins.

A typical furnace is generally indicated at 16 in FIG- URE 3. A stack of three coils 17, vertically arranged, is shown disposed within this furnace on a suitable base 18. The improved annealing cover of this invention is placed over the vertical stack of coils within the furnace and around the base. In the modification illustrated in FIGURE 3 the cover 10 is provided with a reinforcement angle 19 around its bottom. This angle is L-shaped in cross section, the foot of the L extending outwardly under the cover, the leg of the L being welded to the interior cover wall. Usually a sand seal 20 is heaped up around the bottom of the cover to help prevent any leakage.

Although the lid and lifting ring heretofore described are preferred, it would be possible to employ the standard, flat or dished, lid with lifting hooks on the sides of the covers. Also, it may be desirable to provide a few additional corrugations running either vertically or perpendicular to the helical corrugations. These could be corporating specifically the helical corrugations herein described,'achieves all of the objects and advantages herein formed after the strip leaves the machine which imparts the basic helical corrugations thereto. These crosswise corrugations do not have to be full depth, i.e., they may consist of a series of indentations in the crests of the helical corrugation. Although not extremely critoial, the indentations should be aligned generally vertically to provide some column strength to help prevent sagging of the covers.

And, while stainless steel is preferred, any grade of steel or other material that will withstand the high temperatures usually encountered in annealing processes may be employed. While eleven or twelve gauge stainless steel is preferred, it may be possible to employ stainless steel of eight through fourteen gauge.

The improved annealing cover of this invention, in-

set forth. It will be understood, however, that while this invention has been described in terms of certain particular structures and arrangements, the invention is not to be limited to such structures and arrangements except insofar as they are specifically set forth in the claims which follow. Also, it is likely that it will be apparent to those skilled inthe art that modifications may be made in the inner cover of this invention without departing from the scope and spirit thereof.

The prior art closest to this invention and known by the inventors and their Counsel comprises United States Patents 2,136,942, Freeze, 2,136,943, Freeze, 1,421,212, Goodsell and 2,998,236, Cramer et al.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An inner annealing cover adapted to be placed over coils during box annealing in a single stack annealing furnace and comprising a lid and a substantially cylindrical shell of sheet metal, said shell being vertically disposed and comprising a single helically Wound corrugated strip of stainless steel in the range of 8 through 14 gauge, said shell being further characterized by the absence of separately formed s-titfeners, said lid being attached to the upper end of said shell, said strip having mating edges constituting a seam, and means joining said edges tightly together.

2. The annealing cover of claim 1 including a plurality of upstanding vertical fins fixed on said lid, and a horizontally disposed lifting ring attached to said fins, Whereby said cover remains vertically disposed when it is moved from one place to another.

3. The annealing cover of claim 1 including a plurality of crosswise corrugations aligned generally vertically.

References Cited UNITED STATES PATENTS 63,701 4/1867 Carroll 22072 X 983,912 2/1911 LOVekin 12699 1,333,229 3/1920 T0168 126-99 1,421,212 6/1922 Goodsell 26349 1,684,391 9/1928 Green 264-49 2,087,393 7/1947 Wilson 12699 2,344,538 4/1944 clOvvley 2304-83 X 2,374,609 4/1945 McCollum 126116 2,936,724 5/1960 Bishop 18 2,998,236 8/1911 Cramer et al. 26340 3,097,837 7/1963 Jacob 263-49 CHARLES I. MYHRE, Primary Examiner. JOHN J. CAMBY, Examiner.

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