US2764808A - Method of producing a protected metal article - Google Patents

Description

Oct. 2, 1956 2,764,808

METHOD OF PRODUCING A PROTECTED METAL ARTICLE A. w COFFMAN Original Filed June 4, 1949 IN V EN TOR.

my a .M mm mm 1% A TTORNEV United States Patent This invention relates to a method of teeted metal article.

An object of the iflvehtibn i's te ia'rotide e hevel and imprdved method of firodtieiiig iiid tetd irie'tal hftiels forming the suhjeet iri'tttter of thy Ur'iited States Pateht 2,073,334; da'ted Me reh 9, 19 37, atid- 15y which superior proteeted metal ertieles may he predueed in eceriorhi'ca l, rapid arid efiieieht With this gehe'ral ehje'etifi view a'fid stttfh e'tliers as may he're'ineifter appear, ihv'ehtieh eohst'sts iii the method of making the pitefd tfie'til ert ie' heteifiafter described 3116 particularly defih'etl iii the eliiiis at the end "of this specifi'eatibn.

In the drawings, Fig. l is diagrammatic view iii side elevation of the present apfiar'afli's fer pre'dueih-g p'tdt'e'ted metal sheets; Fig. 2 is a set'itiilhl detail of the firdfe'ted metal sheet produced by the apparatus of Fi l, and Fig. 3 is a detail in hem eleyatioh illtist-tatiiigthe the: ehai'i'isrn for trhhrhih-g' the edge ier-hens 6f the firiwteted metal sheets: i

In general; the present invention seeks t6) prevlde im roved niethed of producing preteetetl metal ert iele of the tyifi disclosed in my patent ahoye' r'fefrd to which coln'ptises metal with: 10, preferably ah ireh or steel sheet having layers 12 of fibreus nitteril; ire? erably 'asbstos p l'p'r or felt, securedto tit least @he and preferably re Both df the "opposite stitfaees therecsf by all preauelhg a preinterposed layer of metal adhesive 14; The metal 36- hesive 14 preferabl completely ehveleps the metal sheet and may comprise a nen-eorredible' metl such as zinc; tin, cadmium, lead or ether HOlT-cbfiddih'l rhe'tal 6r alloy, and the metal adhesive is ztlloyed to the rhetal sheet 10 and keyed or anchored to the fibers comprising the fibr 'ous; layer 12. In practice,- the' flbreus layers may he saturated with a suitable itnpre'gnaht eemprisrfig preh erably ebitumirious c emposi-tioh; such as asphalter resinous material or the like, hr with a'n'y' df the other eommer'eial imptegharits which have b'eeh- 01* may be found suitable for use for impregnating sueh fibreus layers, and if desired,- the pfotect'd metll article thus far described may be further protected by eh (l fl't'l weatherprcefing eoatin-g 16" which niay orhphise' any desired c'ompositiori of bitumiii'olls 1"'r1aterittl, Wea'thetresisting iesins, or resinous edrnp'ositions and id pfaetiee, a bituh'iihoti's composition inelu'dihg dottbnseed pitch and asphalt he's been found to pessessthe desired weather resis-tariee and du rability.

The apparatus aridfmethod for prdtrcing' protected metal sheets illustrated inmy Patent No: 2,073,334; above referred to, and the commercial process he'retofm e em ployed in the prdduetieni of such p'rotect'ed metal sheets have contemplated the passageefi successive steel sheets through a galvanizing bath; and as the sheets l'aye the bath they are eond ieted' upwardly between a pair of exit rolls and are their immediately conducted a direction substantially at right edges to the direction at which the sheet left /es the bath. In other Words, as the said patent.

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metal sheets leave the g'ahahizingheth they are passhig in e genera-1 v'eitital direction arid the eeu'rse of travel of the sheets is tllfi defleetea to {e herizez'htal direetihr'i as the sheets pass Betvveh the hdfidirig rdll's by which the fihro'us la'yeis are rolled onto the gely'etiil'iing eeatin befdre the latter hais" heizme solidified as illilstitted iii Experiiie hts defndfistrhlted thtt method of manufa'ttiiing the pfdteted metal sheets intto'dii'ces seveiail di fiiciilties, aild the resent invehtioii seeks am'oiig ether things t'cijarovlde a method aiidtp paidths Whi-eiii these difhc'ultis they be avoided. The fdlldfi/ih'g indiates sofne (if these 'diffieiiltiefs Because at the size and bulk or the bonding rdlls aiid other associated equipment zirl'd supp'dltiing structure, it hid been found nee-essary iii praetiee t6 lote the bond ing rolls seye'i al fe't aiivhy friiiii the exit iolls of the galvetnizing bath, with the resiilt that niehiniel guiding mechinisr'n had to he provided f'cii coildiictin the sheet from the galvanizing bath to the hehding' ro'l s, aftieit leirly is the direction of ttaivel ef the tne'tzil sheets in passing ffcinl the galvanizihg batli tethe bending rolls had to" be altered sub'steiht'ially it wesr ehd thtt the gti'idiiig ihe'ehdni'siitseoi ed the Iinde'r'sid of the fieshly applied galvanized surface of t e sheet so that the the he zinc cdatiiig was abraded ttfid merited B'y eqntetet with the guiding Inehafiis'm and as a fs'fllt the tl'riifdilnity of the zine cdatiiig en the uhdershijfeee 6f the steel sheet beihg" preeessed was de's'trey'ed; This led; of unit mif'y' tended to produce ltck er 'adlisidli Between the fib'rous sheet Add the undersurf ee of the steel sheet zit the fibiuts Where the iiitrkihg had ee'ehrred. H

Another ditfieu'lty exeeiieheed in' the firaletic'al esera' tioi'i of the afifi'ratus shown in p'atnt 'ahoiie' referred to, arose from the fact thtt the sli ht excess 6f zifi was rolled off the end of the gr'lyziliize sheet by the h'oiidirig mils wh n the eiid of the sh'e'et reeehed the fiiii er he hills. This z'iiio Wes de iwb sited iii sihall intisss' lyjoh the adjacent suretee of the felt heihg fed ever the" lewer bending toll aiid heri'n'ted the felt Fayer' during the behciin'g d'per'atioii end fdtz'r'ied iii drape hpo'ii the surface of the felt laiy'er thus headed ta the uhdersicle of the steel sheet,- in many instiiite's dro'pplhg down Ohio the fibrous ove'riiig which was iisutlly irsed to" eo' er the lower hdhdir'i'g roll. This talies p eee w ile the zinc is in a matte-her fit'iid Condition; eifid' ftei" ex'e'ss zirlo which filldS its entry the lower roll and solidifies, it is then forced 15y thf bonding rolls into the surreee at the su c'cdiiig written-s er the fib'i dus' felt durin'g the eo'ht'ih'u d opefeitieh ef the separa es, r'uptu'ritig the felt and at the seihe time poi-rnar'kihg' the surfziee or the lower horiding rol'l. "Cdritihued deems-eh ever t p'riod (if time produced stieh indentttiotis in the hehdingreils that pressure at the seeding rolls across the width of the reieeted metal sheets being preuueed it passed through the mending ren eeeeme he lenger unlifofiri; hilt was l'ocaliZe'd at the high phi-ms of the irregular surface of the mills, "produclng eree' s di/ei' the surfte' of the irote'cted the't' all sheet where blistering eecuried dlie to the defective boiid'il ig becruse of the uneven presstires produced. Iii additidn, the depressed portiolisf'e'sultifig in the libriding' loll because of the 156K? iiiz't'rks", p'roduee'd areas of 10W tires re r'esuitihg ir'l blis= tering between the felt tiidthe g'lvtiiiiiihg (floating due to leek of preper hoildir'ig pressure at sueh points;

Another diflieulty elifieriefi'ced with the ftSregOin'g 815- aratus is the produetidn at at; ih'e uahty 6f the derisit'y or trn'ourit of metal coating, stitch as ghl'vth'izi'hg coeiti-rig, upon the bottom and top' sides of the steel sheet.- This results firimarily from the fact that as the metal sheet leaves the coating bath its direction of travel isehnged about 90 so that during the bonding er the fibrous sheets thereto the metal sheet assumes an are or a e'ur'yd creating the inequality of metal coating, and in practice it has been found that the fibrous sheet upon the upper surface of the completed sheet is always more uniformly bonded to the steel sheet than is the fibrous sheet secured to the lower surface thereof. While the various operational difficulties above set forth detract to some extent from the most efficient operation of the apparatus referred to, nevertheless the apparatus has proven to be commercially operative and large quantities of the product produced thereby have been sold.

In accordance with the present invention, a more uniformly and more perfectly bonded protected metal sheet of the character described may be produced by disposing the bonding rolls above the galvanizing bath in substantial alignment with the path of travel of the metal sheet as the latter leaves the bath so that the sheet continues to travel in substantially a straight path until. and during its passage through the bonding rolls. Preferably, the bonding rolls are disposed above the galvanizing bath so that the metal sheet as it emerges from the bath, travels in a vertical direction. This enables any excess zinc on both surfaces of the sheet, as it is emerging from the bath, to run uniformly down the sheet by gravity so that the coating weight may be controlled by the surface tension of the zinc itself and also permits this excess zinc to drop back into the galvanizing bath, thus preventing it from finding its way onto the bonding rolls. In addition, regulation of the temperature of the galvanized coating upon the sheet between the time that the sheet leaves the coating bath and the time that the bonding operation is performed as the sheet travels between the bonding rolls, contributes to most efficient bonding.

The temperature of the coating of zinc upon the galvanized metal sheet during the period of time the sheet is travelling from the point where it emerges from the galvanizing bath to the point where it passes between the bonding rolls may be regulated in various ways. In the preferred method and apparatus provision is made for adjusting the bonding rolls vertically to shorten or lengthen the distance of the same from the bath and in that way to maintain the temperature of the coating of zinc upon the sheet at the point of bonding within a predetermined range. The temperature range at which bonding takes place may be elevated or lowered by shortening or length ening such distance as the case may be. This adjustment of the bonding rolls toward and from the bath may be effected manually by mounting the rolls on vertical slides and adjustably clamping the slides in different positions corresponding to the desired position of the rolls. In some instances I may prefer to provide automatic mechanism controlled by the temperature of the coating bath for automatically adjusting the vertical position of the bonding rolls. In some instances I may prefer to maintain the bonding rolls in a fixed position and to utilize auxiliary heating means for providing a controlled and heated atmosphere through which the coated metal sheet passes as, it emerges from the bath in its travel to the bonding rolls. The control of the temperature of the coating upon the metal sheet at the time that it is ready to pass through the bonding rolls plays an important part in obtaining the most satisfactory bond between the fibrous material and the metal sheet, and in addition enables the thickness or weight of zinc coating on each side of the sheet to be carefully controlled to the end that the steel core sheet may be satisfactorily and most economically weatherproofed.

I prefer to employ one or more of the foregoing methods of controlling the temperature of the metal adhesive coating on the sheet as described in order that the continuous operation of the machine may not be interrupted, stopped, or slowed down, in order to compensate for any variations occurring in the process. For example, when the apparatus embodies a galvanizing bath, if fresh zinc is added to the bath, quite naturally the zinc bath will. drop somewhat in temperature. This drop in temperature of the bath may be rapidly offset by a movement of the rolls closer to the surface of the zinc coating bath. Likewise, if during the process a different gauge or strip steel or sheet steel were to be processed, the bonding rolls would be moved somewhat nearer or farther away from the bath, depending upon the heat balance which resulted in the steel strip. i

It is a fact that during solidification of the molten zinc coating upon the metal sheet, after passage of the sheet through the bath, the coating passes through a so-called mushy stage due to the presence of small impurities. For most effective results, the bonding operation should take place at a temperature reasonably near, but above, this mushy stage. It has been found that the sheet steel of various gauges when heated in the galvanizing bath at 850 F. and removed therefrom, have on their surface a liquid zinc coating which solidifies when exposed to the air after varying lengths of time, depending upon the gauge of the steel. For example, 26-gauge steel so treated results on exposure to room temperature in a solidification of the zinc in ten seconds; whereas IS-gauge steel upon cooling under similar conditions for thirty seconds has a zinc surface which is solid. It can, therefore, be seen that a change of gauge, a change of air temperature surrounding the steel strip coming from the galvanizing bath, fluctuations in the speed of travel of the steel strip, and fluctuations in the temperature of the galvanizing bath all have a distinct bearing on the relative location of the bonding rolls to the bath to assure the most efficient position of the rolls at which the bonding operation should be carried out. With properly designed bonding rolls which can be rapidly adjusted in height above the galvanizing bath, the problem of balancing all of these factors may be readily solved.

Referring to the drawing which illustrates a protected metal sheet and the preferred apparatus for practicing the present invention, a coil 11 of either hot or cold rolled steel strip may be operatively supported in a suitable standard, not shown, and from which an elongated strip of steel may be conducted into the galvanizing bath 13 contained within the galvanizing tank or pot 15 or individual lengths or sheets of steel may be fed by suitable feed rolls, not shown, into the galvanizing bath. In some instances it may be desirable to feed individual sheets cut by shears 17 from the continuous coil of steel and in any event the individual sheets or the continuous strip are passed under bottom rolls 23 located below the level of the molten zinc, lead or other metal in the bath and from which the sheets or strip are caused to emerge by driven exit rolls 24 located above the bottom rolls 23 and preferably arranged side by side so as to permit the coated steel sheet or strip to emerge in a vertical direction from the bath. The design, combination and location of the various rolls for handling the steel sheets or strip in and from the bath may depend upon the type of galvanizing process used and particularly upon the presence or absence of a flux.

In the event that the galvanizing coating bath is operated with a flux, it is preferred to provide an exhaust system including hoods 30 connected to an exhaust fan 32 for drawing off any fumes from the flux or if desired, suitable shielding members 34 may be interposed between the galvanizing bath 13 and the bonding rolls indicated generally at 25, in order to prevent the volatilizing flux from depositing excessively on the galvanized sheet or upon the fibrous layers to be bonded thereto as in either case the deposited flux when contacting the hot coated steel prevents the most perfect adhesion of the fibrous felt to the steel resulting in a blistered product.

In accordance with the present invention, the bonding rolls 25 around which the asbestos felt or other fibrous layers are caused to pass from supply rolls 26, 27 thereof comprise steel rolls which are driven to advance the sheet of steel passing therebetween, and in accordance with the present invention are. arranged side by side in a subspreeos stantially horizontal position such as to permit the steel sheet after it has left the exit rolls 24 from the .galvin-i-zifig bath 13 to pass in a straight path and to avoid any sub= stantial deflection of the steel strip until after it haspass'ed through the bonding rolls. In practice, and as illustrated herein, it is preferred to mount the bonding rolls together with the supply rolls 26, 27 upon a movable carriage 40 by which the entire assembly may be bodily moved into a position to one side of the exit rolls 24 leading from the galvanizing bath 13 to thus expose the entire galvanizing bath and to afford access thereto. Preferably, the entire assembly is also mounted to permit it to be moved vertically toward and from the galvanizing bath, and these results may be accomplished as herein shown by mounting the framework upon which the bonding rolls and associated parts are assembled, upon two uprights 42, 44 to be elevated by hydraulic or other means and also to permit the entire assembly to be dropped down when such pressure is withdrawn or lowered. As herein shown, the entire assembly is movably mounted upon rails 30 to permit the entire assembly to be moved laterally as described.

During the withdrawal and travel of the asbestos felt layers from the supply rolls 26, 27, it is necessary for best operation to preheat such felts in order to remove all moisture and also preferably most of the binding and organic material in the felt. Such procedure is necessary first to produce a moisture-free felt which will not blister when it comes in contact with the coated steel, and secondly, to give a more or less porous felt which will be best suitable for saturation in the successive steps of operation, as will be described. For this purpose various types of heating devices may be employed, herein shown as a series of gas burners 50, so located that the gas flame impinges on the surfaces of the asbestos felt which are to come in immediate contact with the zinc or similar coating upon the steel strip during the passage of the coated steel and felt between the bonding rolls 25. It is important that the gas burners be located to direct the flame in this manner because if the heating were to be directed against the opposite side of the felt, small quantities of volatile material would remain on the surface of the asbestos felt which is to come in contact with the zinc or other coating and such a procedure would result in blistering due to the rapid volatilization of such constituents under the heat contained in the coated steel.

In passing through the bonding rolls 25, the zinc coating on the steel is forced into the interstices of the asbestos felt and simultaneously, at least in part, solidifies due to removal of the heat from the assembly of felt and steel, and as the steel strip issues from the exit side of the bonding rolls, the asbestos felt is firmly attachedto the strip of steel. In the bonding operation, it is desirable to employ asbestos felt somewhat wider than the strip steel used, so as to compensate for any slight lateral travel of the strip or of the asbestos felt. Therefore, the assembly issuing from the bonding rolls has an excess of felt extending beyond the lateral edges of the steel strip. This excess material must be removed from the strip, preferably before the strip is impregnated with asphalt or other impregnant. In order to accomplish this removal, the sheet is carried up through the conveyor where the trimmer device 58 is installed. As herein shown, this device consists of two grinding wheels 59, 60. The upper wheel 59 grinds off the excess of the upper felt, and the bottom wheel grinds off the excess of the bottom felt. The springs 64 are adjusted in such a way that the grinding wheels aways follows the strip edges even when the strip tends to move in lateral directions. By creating V shapes on both edges of the passing strip assembly the wheels hold the strip closed by the two bot toms of the VS and do not allow it to move in vertical direction. The wheels may be made from regular Carborundum or from special steel and may be of cylindrieel form as indicated. As the grinding operation creates asbestos dust, an exhaust system is preferably provided to remove the dust to an accumulator. i

The trimming operation has to' remove not only the excess felt but also the excess. zine which is squeezed from the surfaces of the steel and accumulates at the edges of the strip during the bonding process. Therefore, the trimming device should be installed near the bonding rolls in order to grind off the zinc excess when the zinc is not too hard but still in the more or less plastic state. After the trimming of the excess felt and zinc, the product is saturated in asphalt or other waterproofing impregnant.

As described in U; S; Patent No. 2,073,334, the satu rating operation is preferably carried out in a single pass through a saturating tank 70. While such a, procedure results in a partial saturation of the asbestos-covered strip, the saturation is far from complete, and in order to achieve complete s taturation, it has been found that the asbestos-covered strip must be passed through a saturating tank having more than one set of squeeze rolls 72. As indicated, the strip passes beneath the surface of the liquid asphalt at (a) and then passes through the first set of squeeze rolls 72 which remove the excess of asphalt on the surface of the asbestos-covered sheet, and then the sheet passes through a second clip at (b), followed by a second set of squeeze rolls 74 which again remove a large part of the excess asphalt on the surface of the asbestos felt. A final pass through a set of hot rolls at 76 smooths out and makes more uniform the entire appearance and surface of the saturated asbestos on the steel. By such a procedure, it has been possible to build up the saturation of the asbestos felt from about 25% to a maximum of about 40%. That is to say, the asbestos felt, by successive dippings, in more or less completely saturated rather than left in a partially saturated condition. The problem of saturation is more difficult than the saturation of ordinary felt since, in the saturation of felt, the saturation takes place from both sides of the felt surface, whereas in this procedure all saturation must be from one side of the felt only, since a metal sheet separates the two layers of :felt bonded to the surfaces of the steel. A further improvement in the saturation process is that the saturating tank is mounted to be movable. Its location depends on the speed and gauge of the strip. Furthermore, due to its special shape, the level of the asphalt contained in the tank can be regulated thus permitting the operator to regulate the saturation time and obtaining a dry product. By these improvements, in the design of the saturating tank, the easy and quick adjustments of the saturating process is achieved, and when the facors such as temperature of asphalt, distance from bonding rolls and level of asphalt are synchronized with the gauge of the passing strip, the saturation process reaches practically the maximum of efficiency.

Subsequent to the saturating operation, the strip is permitted to continue its travel due to the action of the pinching rolls 80 to the shear where is: can be cut to the desirable lengths and loaded on the buggy 86 or the strip may be conveyed to the recoiler machine 88 which is equipped with a cut-off device 90 as used in standard practice and which is preceded by several idling rolls 92 to permit handling of the continuous passage of the strip through the complete line of manufacture. The abovedescribed operation results in the manufacture of asbestos-protected strip in coil form in which the asbestos is saturated with asphalt or other suitable impregnating material. This product may then be uncoiled, passed through a roller leveler, cut to length and provided with a weatherprof coating as previously disclosed in U. S. Patent No. 2,073,334.

This application is a division of my application Serial No. 97,246, filed June 4, 1949.

Having thus described the invention, what is claimed 1. In a method for producing a building sheet, the steps of passing a sheet of core metal through a bath of molten non-corrodible metal and upwardly out of said bath in a substantially vertical straight-line direction-to carry a substantial film of fiowable molten metal therewith on the surfaces of said core sheet, moving said sheet in said direction, without substantial deviation therefrom, and simultaneously and continuously directing and horizontally pressing asheet of fibrous material against each said surface of said core sheet and into said molten metal at a predetermined station along the vertical straightline path of travel of said core sheet, and controlling the temperature of the coating of molten metal adhering to the core sheet to maintain it in a flowable condition be tween said bath and said station whereby molten metal squeezed from said film by said sheet pressing step flows along said film directly to said bath, along both sides of said metal core sheet.

2. In a method of producing a building sheet, the steps of passing a sheet of core metal through a bath of molten non-corrodible metal and upwardly out of said bath in a substantially vertical straight line direction, to carry a film of molten metal therewith on the surfaces of said core sheet, moving said core sheet in said direction, without substantial deviation therefrom, simultaneously andcontinuously directing and horizontally pressing a sheet of fibrous material against each of said surfaces of said core sheet and into said molten metal at a predetermined station along the vertical straight line path of travel of said core sheet, and controlling the temperature of the atmosphere surrounding said path between said bath and said station to thereby regulate the temperature of said molten metal between said bath and said station.

References Cited in the file of this patent UNITED STATES PATENTS 2,031,035 Dreymann Feb. 18, 1936 2,073,334 Cofiman Mar. 9, 1937 2,135,886 Elder Nov. 8, 1938 2,330,530 Tuttle Sept. 28, 1943 2,349,951 N Fuller May 30, 1944 2,631,641 Coffman Mar. 17, 1953

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