USRE14794E - By the libbsy-owews - Google Patents

Description

I. W. COLBURN", DEC'D.

- 'THE LIMEY-owius sneu eLAss couPAuv. Assmln.. l METHOD 0F AND APPARAIUS Fon-DRAWING SHEET GLASS.' A

AAAAAAAAAAAAAAAAAAAAAAAAAAA I ,e Shins-shin A I |I I I III I II l( gg .Il 'HMI IIl Il r IIIIIIIIIIwww@ fr I I "l". w. CO'LBURNQD'ECW. TH.; LIBBEYJHIENS SHEET GLASS COMPANY, ASKSIGNEE. METHODUF AND APPARATUS DRAWiNG SHEET GLASS. Reissued Jan. 2 7, 1920.

APPLICATION .FILE-D NBV. 29 [919.

W. COLBUHN, DECD. THE LlBaEv-oweus SHEET GLASS COMPANY, ASSIGNEE.

METHOD 0F AND APPARATUS FOR DRAWING SHEET GLASS. APPLICATION min Nov. 29, Isls.

e SHEETS-SHEET 4.

Reissued Jan. 27,1920.

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APLICATION f-LED NOV. 29,1919. Relssued J an. 2f, ,1920.v

UNTTED sTATEs PATENT @einen IRVING W. COLBUEN, DEGEASED, LATE F TOLEDO, 01H10, BY THE LIBBEY-DWENS SHEET GLASSCOLVPANY, QF TOLED, OHIO, .A CORPORATION' OF DHIO, ASSIGNEE.

METHD OF AND APPARATUS FOR DRAVJ'ING SHEET-GLASS.

Specification ofReissued Letters Patent; Reissued Jan. 27, 1920.

Original application filed January 29. 1308, Seriel No. 413,296. Renewed March 26, 1912, Seral'No. 686,460. Grigna). No. 1,160,692, dated November 16. 1915. Application for reisspel filed November 29, 1919.

Serial No. 341.533,

To all whom if may; renown.'

Bc it known thnt IRVING lV. COLBURN, deceased, und lote :i Citizen of the United States of America, and n resident ot Toledo,

Ohio, duly invented o new 'und useful lmprovement in Methods of und Apparatus for Drawing Sheet-Gloss, which invention is fully set forth in thetollowing speeiiieation.

This invention etes-to the nrt of drew# ing gloss in sheet form from n mass of .molten gloss.

"When efforts nre mede to drew o. sheet of glnssirom n molten mass of there is a tendency upon the pzirt oit' the sheet being drawn to rupi-dlg; narrow, and unless ineens are provided for overooming sueii tendency the sheet willsoon pull to o, stri-ng or thread.

In n number of il. S. patents some of 2O which were granted to me solely end some jointly with Edgar VVnshburn, there ere disclosedv certain methods andl apparatus for drawing glnssuin Sheet form, which methods end forms of apparatus inc-ludesteps and meehnnismfor maintaining the Width of 'the shoetd'uring the drawing operation. These methods and forms of apparatus disclosed in the patents aforesaid in practice have proved oiliieiont.

The method' and apparatus constituting the present invention are designed to be used in connection with 'any 'suitable sh'eet glass `drawing apparatus, and is particularly op plieable to o. machine of the character set forth in my U. S. Potent 836,439, ond my U. S. application Serial o. 368,09,liled April 13,1907.

The particular object of the present infvention is to 'pi-@fidesA method and oppnra- 40 tus for avoiding or overcoming the narrowing ol the sheet of glass during the drawing opei'ntion, which method and apparatus shall be more eiieientin practice, Simple to construct, and more readily operated than those known'in the art prior to the present invention. y v I these objects in vie-iv, the invention resides 1n the method of drawing' sheet gloss, which consists in preparinge mass'of molten gloss Whose temperature etthe points.

where the edge portions of the sheet emerge 4 :nid in additionthereto applying u, dran from said molten mass, is loWer'th-Ln is the temperatureof the molten mass as a Whole, and particularly lower than the' temperature of the molten mass along the line Where the sheet of gloss emerges from the molten moss between said points of lower temperature, and then drawing n, sheet of glass from seid moss thus prepared with the mein body porl 'tion of the gloss emerging from the molten 60 mass which has the, vhigher temperature, While the edge portions of the sheet emerge or ore drown from the tivo punts of the molten mass having the lower temperature.

rlllie invention further consists in regulnting the tempel-o ture et the molten'moss pessing into the edge portions of the sheet and the temperature of the molten mess passing into the main or middle portion of the sheet, so that the desired difference in temperature between the middle and the edge portions niej/(be maintained the point Where the best results may be obtained. Thesewill vitry for diil'erent thicknesses of glass be drawn and therzttes of movement of 'the '.75

sheet during the dro-wing operation.

i The invention further consists in o" 1n ge drawing action to the sheet' as n wl:

eetion to the edge portions-of the sheet, W -e drab-.nung action may ,be regulated as to its rnpidityoi movement with relation to the dwiviing action exerted uponv the sheet as a' o e.- l The invention further resi'des in a. recepT 85 for o mass of molten glass, combined with inea-ns for' applying heat to the molten mass in the receptacle, seid receptacle end means being so constructed-:md combined tlwet the portions of the molten mass in the reeeptn-ele fromr which `the edge portions of the sheet are drawn shall be of, a. lower temperature than the middle or main portions of the receptacle from which the main body` of thevsheetof glass is drawn. 95

The invention further resides in conneetion with :i suitable reeeptaele'for 'molten glass of the Ageneral character last describV d' of means acting to draw the sheet of glass y ny Whole 4from the molten mass, ycombined .with drawing` meansacting solely uponthe.

the drawing operation so far as'tlie edge portions are concerned. iUnder some conditions, in order to` obtain the 'best results, it .may be found desirable to drive the main sheet-glass drawing means of the machine at a difeient rate of speed from that of the means for drawing the edge portions of the sheet, and with this object in4 Yiew, means .are provided whereby said edge portions' may be operated at a different speed from that of the main sheet-drawing portions; and also means whereby the two sets of edge-drawing portions'inay, if desired, be

' driven, the one at a different rate of speed vso vfrom the other.

tion on the line IIL-'III of Fig. 2; Fig. 4-

isfa vertical and longit'iidinal section ofthe working chamber end of lmy continuous glass-work ng machine shown in my application No. 368,096, with my improved width-hoiding or maintaining device api plied thereto instead'of the width-holding or maintaining devices shown in said apsection on-the line V--V, Fig. el, pai-ts being shown in elevation; Fig. 6 is atop plan view.

of the edge-engaging or supplemental drawing rolls and their operating mechanism; Fig. 7 is a side elevation of Fig. 6, and Fig. 'S vis an end elevation, parts being shown in section; Fig. 9 is a` broken sectional detail illustrating the means for cooling thev supplemental rolls; Fig. l() is a plan view of a working chamber, in which the cooler area from which -tlie edge portion of the sheet emerges differs somewhat in form from thatv shown in Fig. 2; Fig. 11 is a side elevation of the lower portioiiiof the edge of a sheet'v as it is being drawn in a .working chamber' such as that shown in F is -a sectional View on the line KHS-XII, fFig.` 11; and Figs. 13,14 and lillustrate modified methods of obtaining the cooler edge-forming area's. A

Like numerals indicatelike parts throughout theseveral views.

',Fig'sf 1V?, 3,' 5 and10 all'disclose sufficient portions of the working chamberl and drawing apparatus shown in cation No."ii, to clearly 'illustrate the rela/tion-ilxid application of my present v'invention thereto.=

. porti ons Ato -th'e rolls 1, v2, -and vtween-the eXtei'ior 5 is a vertical transverse` ig. 10; Fig. 12`

my said appli-f In carrying Vout .my improved process, any

suitable form of sheet drawing machine maybe employed, but'preferably I use the. form of' working chamber .and drawing apparatus shown in my said application, Sr. No. 368,096. In the present invention, however, the revoluble spheres shown in -said application are omitted,A and the sheet is maintained of uniform width and the edge of the sheet drawn by the apparatus and in the manner now to be described.

Referring to the drawings, and particularly to Figs. 1,2, 6, '7, 8 and9, two rolls 1 and 2, each preferably having a milled or I I kiiurled surface, are mounted vupon tubulai shafts 3, e, respectively, which pass "-rev# olubly through bearings 5 and 6. v,Stuffing boxes '7 are provided on theeXterioi' ends of the shafts 3, 4, and throughsaid boxes pipes 8, 8 pass within the tubular shafts 3, 4, and terminate within the hollow rolls 1, 2, within a shortjdistance of the end of said rolls. Vater or other cooling fluid enters through the, pipes 8 and Ais conducted passes outward beof thepipes 8 and the interior of the tubular shafts 3, 4, and passesv by way of the outlet 7 to the sewer or other. suitable placeofdischargeiI The bearing 6 is'rigidly mounted upon a suitable base 9, while bearing is'so mounted on said base as to be capable of a slight horizontally'rotative movement,- in

may be withdrawn from or caused to approach toward the roll A2, `as desired'.A` A

ever l0 is rigidly 5 and projects rearward, and at the outer end of said lever is attached a spring connection 11, the normal action of which is to press the roll 1v toward the roll 2, as will be clearly understood from inspection of Fig. 6. Motion. is imparted to shaft l through the medium of beveled gears 12 and 13, and is transmitted to shaft 3 through the intermeshing` spur gears 14 and 15,

power is applied. for revolving the rolls, in

order that `the roll 1 attachedl tothe bearing.

which are keyed to` or otherwise secured to the shafts 3 and #i respectively.

a manner hereinafter set forth. As thus 11,5

constructed,4 one. set of the drawing rolls is mounted upon each side of the working chamber of' the continuous glass-drawing*- machine; the rolls being in proper positionv to Aengage the edge. portions being drawn. Thev sheet" l-may be a ibait or other suitable started means-of device in any usual 'or well-knownmanner, and the drawingjoperation, if preferredmaylbe continued by 1 rneansfsuch a's those fully-setforthinmy said application, lSr, No..36i8,09i6 Byjthe present nivention, however; theledge p ortions'of the sheet are drawn -froma portion themolten ,glass inthe" Working cham,

of the sheet 129'v ber 'which has a lower `temperature than the lremainder of the moltenmass or that portion of the molten mass from which the main body of the sheet is drawn., Any suitable means for providing areas ot' lower temperature 'from which. to draw the edge portions .may be employed. Preferably, I provide the working chamber with side recesses vor bays 17 (see Fig. 2) for the purpose of 1. securing areas in the molten mass which are of a lower temperature than that of the mainj portion existing in the body of the workingA chamber 18. It is essential that the areas of the molten glass from which the. edge portions of the sheet are drawn should be of e bdu'stioh chamber 22, and this heat takes the course indicated by the numerous arrows in Figs. 2 and 3. A portion of the heated gases' of combustion pass over and by the ends of the rib-annihilating or skimming rolls 23. In addition to this, said rolls become highly heated and large quantities' of heat are delivered by radiation to the areas of the working vlchamber between the rolls as they vare revolved. It will be noted that bays 17, 17, are not so directly exposed to the .action ot any of this heat as are the other portions of the working chamber', and hence the' temperature therein is normally somewhat lower, andthe glass therein consequently so "iewhat less plastic, than` in the main 0r central port'ion of the working chamber. In fact, the

. 4glass in the bays 17 would soon become comiparativelfy cold,` and would be unworkable if rneans were not provided for heating the glasswithin said bays. For this purpose I provide suitable burners, such as the Bunsen burners 24, 24, whereby heat may be directed intothe' bays and upon the edge-forming area ofthe molten glass, the temperature of the glass in said bays, however, being easily 'regulated by controlling said burners. As the sheet is drawn, the edge portions thereof are drawn from or formed'from the molten Iglass in or immediately adjacent to 'sa-id bays, where the glass is cooler, and consequently thicker or more viscous, than that in thejmain portion of the working chamber from'which the main bod of the sheet is drawn. From this it-resu ts that theedge mportions of the sheet are more tenacious and ess treatable or` pliable than the main body turc., w

of the sheet, and this results in the edge portions of the sheet as they emerge from the mass of molten glass being thicker than that of the main body 0f the sheet. It therefore becomes necessary to employ means for rcducin the thickness of said edges, to the end that tl: y may be of substantially uniform thic-knt with the sheet proper,P in order that the sheet will pass properly over thc bending .oll 25 (Fig. Ll) and down through the drairing chamber and annealing o\cu.

Meromv f, by reason of the lower temperah the consequent increased viscosity and tenacity of the glass from `which the edge portions of thc1 .sheet are drawn, the

resistance incident to drawing the edge portions of the sheet is greater thinthat obtain-.

ing inthe main -body or middle portions of the sheet, and in order to overcome this additional or increased resistance, and in order that the draft tension ulpon the entire sheet may be uniform or equa ized throughout the width or transverse section thereof, -I employthe supplemental drawing rolls shown in Figs. 6, 7 , f 8 and 9, and hercinbcfore dcscribed. (lne set of said drawing rolls is mounted upon each side of the working chamber 18 in close proxin'iity to the mass` of molten glass, and so positioned that each' set of rolls is in position to receive between them one edge of the sheet being drawn, while'vthe shafts of said rolls `extend l'iorizon-I tally outward. as clearly shown' in Figs. 2 and 5. For the purpose of driving the rolls, shafts 12, l2. yare attached each to a `shaft 26 V(sce Fig. 5), each driven independently from variable speed pulleys 27, 27, which are in turndriven by a jack-shaft 28 to 'which motion is transmitted through a variable speed pulley 28', lreceiving motion from anysuitable `source of power, here,

shown as an electric motor 29. The other portions of the drawing mechanism are driven by shaft 28 through` the medium of beltSO and chain 31.

By the arrangement of power transmission above dcscribcd it will be seen that the speed of each set of supplemental drawing rolls may bcI individually variedl through the respective pulleys 27, 27, transn'litting power lto each set of rolls; also that the speed of the machine as a whole may be varied :it-thc pulley 28', sotliat the speed of the various elements of the mechanism may thus be harmonious and operation between them secured.

As the sheet of glass forms from molten uniss, it Iassumes at the edges form shown in Figs. 1l and 12, and as thicker edge portions 32 pass between the sets of rolls 1,2, which revolve in the direction shown by the arrows, such thicker porthe the

tions are rolled down to a Ithickness corre-v sponding to' or somewhat perfect col ,sheet helow The rolls l., Q, have knurled or milled peripheriesl to prevent their slipping, and by regulating their peripheral speed ,by means of the 'Variable speed of pulleys 2T, "T, they inay he raused to o\-erooine all of the resistance due to the varying thickness and plasticity oi the molten glass entering into or i'oiining'the edge portions of the the rolls. By thisl means the respective sets ot' rolls aet to overcome the' additional resistance to the drawing operation-due tothe increased thickness and plasticity resulting froni'tlie ture ot' the mass from which they are drawn, and there is thereby secured an equalization ot' the draft tension throngl'iout the entire width of the sheet.

It will of course be understood that for the purpose of leading the water or other cooling Huid into and from the rolls 1, 2, flexible inlet conduits S', S', are connected to the pipes S, and flexible outlet pipes 8 are eonneeted to the outlet points 7'... all as clearly illustra-ted in' Fig. 5.

In son'ie eonstruetions of working chamher, it may not he necessary to provide the inlets or hays 17, shown in Fig. Q, if the construction of furnaceis'suc-h that the areas of the molten glass from which the edge portions of the 'sheet emerge will be cooler than that portion of the molten glass `intermediate the edge portions. Inl that ease, the edge portions of the sheet would be drawn 'from sucli'cooleiai'eas after the inanrier villustrated in Figs'. 1() and 13. In Figs. 14 and 15 there is shown an island of an upwardly projecting portionf of refractory material from which the edge portions of the sheet could be d'rawn,.while'y in` Figs.- l1, and 12 the edge portions ofthe sheet emerge from or immediately adjacent to the sides of thev furnace itself. y

I desire it distinctly understood that I do not Wish to confine inyselil to any particular form. or construction of apparatus herein shown' for produeing my edge-forming cooler areas, as any construction which will admit of obtaining an edge-forming vor iso cooler area of the naturel herein shown Vis within the spirit and scope of my invention.-

lower tempera-vv Moreover', While the burners Qi are shown.

herein as means vhy Whieh the-temperature of said cooler areas is properly `regulated independently of the surrounding mass of glass,fsaid burners are;shown merely as illustrative of means p1oyed:for,this` purpose,' and any means which would perform this function are within the scope oitheiinvention. ,y

VVhatis claimedy 1. The improvement n the. ar't of glass -..working which ,consists in drawing a conftimious sheetoiglass from a :nass of molten points from which glass. which iS 0f which may be'l einf,

lowerv temperature at- "the 'f the edge pprtions of the sheet are drawn than it. is

y areas,

tinuoiis sheet of glass from which the niain body drawn, said drawing being' aceoiiiplished by applying a drawing-power to the sheet as a whole and additional drawing power to the 4 ei'lsije portions of the sheet.

The in'iproveinent in the art of glass working which consists in preparing a mass of molten glass with side portions cooler than theV intern'iediate body of said mass,v

regulatingr the teniperature of said side portions vitli'relation to the temperature. ot' s aid inteiiinediate portion while always maintaining it helow that of said interino diate portion, and then drawing a continu- .ous sheet ot glass hy drawing' the main body along the line of the sheet' is dfa sheetA of 'from said intermediate i portion and the edge parts of the sheet from said Cooler side portions of the molten mass.

3. The iinpro-vei'neiit in the art ot' glass working' wliieh consists in drawing a oontinuous sheet of glass troni a mass of molten glass whose side portions are cooler than the middle or intermediate portions, and siiiiul-- taneously applying` more drawing power to the edgi-x portions of the'sheet than to the interinediate portion of said sheet. Y

4. The improvement in the artor' glass working whieli ronsists in. drawing a tienetinuous sheet of glass from a molten mass of glass vwhose temperature is higher where the main body off said sheet issues from. the

-niolten mass 'thanr at the pointsl where they side portions issue -it'rou'isaid mass, said sheet being drawn hy apply tl'iroughout the width of the sh eet and a further or additional draft al. the edge portionsl of the sheet. i

' 5. The in'iproi'einentin the art of glass working- 'which consistsin drawing a eoiitinuous sheet of `glass from a inass of glass `that is cooler at the points from which the edge portions of the sheet are drawn than is along' the line troni'whieli the main body of the sheet is drawn, and applyingmore' drawing power to the edge portions than to i the main body portion ot the sheet.

G. The method of drawing continuous sheet gl whioh eonsist-s in produoing relatively oool or vless plastic areas in a mass of molten glass, drawing a sheet of glass 4from said niass of molten glass, of causing the edge Aportions of said sheet to he formed from said and 'in teniperingr said areas independently of the surrounding mass.

ing a uniform draft `7. v'The method ot' 'drawing sheet glass i which consists in preparing a in ass of molten glass having one degree of temperature and. plasticitythroughout the greater portion of area thereof' and-a relatively lower degree of 'temperature and plasticity at two several. points thereof, and then' drawing 'a' con- I from said mass, the body of said sheet being formed from said area of higher temperature and'degi'ee of lares plasticity than the main body of the molten mass, -with means for drawing the main .or central portion of a sheet of glass from that portion of the masshaving a relznziwlj.y high .degree Aof temperature and plasticity. and supplemental meansdrawing the edge portions of the sheet of glass from those portions of the molten mass having a relatively lower degree of temperature and plasticity` containing a mass molten plastio glass, means for supplying heat to the main body of the molten mass in said chamber of a higher degree than that supplied to Itwo several areas thereof,` whereby the plasticity of the glass of said areas is of ale-ss degree than that of the main' body of the molten mass, with means for drawing a sheet of glass from said molten mass the edge portions of the sheet being drawn from said areas of lower temperature and plasticity and the main body of the sheet being drawn from the area of high temperature and .plasticity. p J

10. In an' apparatus for drawing sheet glass, the combination of a working chamber having oppositelyr disposed lateral bays,

means for applying a higher g degree of heat' to the molten mass in the main chamber than is applied to the molten glass 1n said ays, and means for drawing a sheet of glass from said chamber with the edges ofthe Asheet Jforming in o r adjacent to said bays, the drafting means for the edgeportions of the sheet being capable of a rate of movement different from that* of the drafting v means for the intermediate portion of the sheet.`

11. In an apparatus for drawing sheetA glass. `the combination with working chamber for containing a -mass of molten glass,

.means for maintaining the temperature of two oppositely disposed areas of the molten In an apparatus for drawing sheet glass,. the combmation of a working chamber for Y molten whereby said main body is Vheated to a higher degree of temperature than lat two several points or areas thereof, means for independently modifying thetem- 'perati tif-said several points or areas, and means for drawing the central portion of tltv sheetof glass from said main-body of the molten mass and the edge portions of the sheet from said points or areas of lower temperature.

13. In an vapparatus for drawing sheet glass, the combination of ar receptacle for containing a of moltenv glass, means for applying heat to the main body' ofthe molten mass in said receptacle of a higher temperature than that applied to certain lateral points or areas of said molten mass, means for regulating the temperature of said lateral points or areas, a main' sheetdrawing `means for drawingv a sheet of glass from said molten mass with itsedge portions issuing from said areas of lower temperature and itsmain portion issuing from the main bodyiof the molten glass in said receptacle, and supplemental drawing means acting on the edge portions of the sheet during the'drawing operation.

14.. The improvement in the art of glass working which consists in preparing a mass of molten glass with side portions of .a different temperature than the intermediate body of said mass, regulating the tempera- -ture of said side portionswith relation to .from saidside portions of the molten glass.

15. The improvement in the artof glass working which 'consists in drawing a sheetl of glass from a mass of molten glass whose side portionsare of a different temperature than the' middle or intermediate portion, and simultaneously applying more drawing power to one portion of the sheetthan to the` other. i

16.` In an apparatus for drawing sheet glass, the combination of a receptacle for containing a mass of molten glass, means for drawing a sheet of glass therefrom, the means for drawing the central portion of the sheet being separate and independent fromr the means .for drawing'the edge portions ofthe sheet, and devices for driving the drawing means for thecentral portion oiv the ,sheet at a rate of s eed. differing from that of the rate of spee at which the edgedrawingl means are driven. 17. The-improvement 1n working, which consists in'drawing a continuous sheet of glass fr om a mass of molten .glass which 1s of lower temperature at the points from which the 'edge portions of the sheet are drawn than it is along the line from wh'riv the main body of the sheet is the art of glass i mass, with means drawn, said drawing being applying a' drawing power to the sheet as a whole and additional drawing power through cooled instrnn'ientalities to the edge portions of the sheet, f

18. The improyement in Athe art of glass working, which consists in .drawing a continnous sheet of glass from a mass of' molten glass that is cooler at the points from which the edge portions of the sheet are drawn. than it alongr the line from which the main body of the sheet is drawn, and applying more drawing power to the edge 'portions than to the main body portions of the sheet, saiddrawing power to the edge portions be "ing applied .through cooled instrnmentalit1es.

19. In .an apparatus for drawing sheet glass, the combination of a working chamber and means for providing a mass of molten glass therein having two several areas of a relatively lower degree of temperature and plasticity than the main body of the molten for drawing the main or central portion of a sheet of glassfrom that portion of the mass having arelatively high degree of temperature and-plasticity, snpplemental means drawing the edge portions of the sheet of glass from those portions of the molten mass'having a relatively lower degree of temperature and plasticity, and means for cooling said supplemental means.

Q0. In an apparatus for drawing sheet lass, the combination of a working chamiier for containing a mass of molten plastic glass, means for supplying heat to the main body of the molten mass in said chamber of a higher degree than that supplied to twol several areas thereof, whereby he plasticity of the glass of said areas is of a less degree than that of the main body ot the molten mass, with n'ieans' for 'drawing a sheet'oii glass from said molten mass, the edge portions of the sheet being drawnv from said areas of lower temperature and plasticity and the main body of the sheet being drawn from the area of high temperature and plasticity, and means for cooling the edge-drawing means.

2l. In 'an apparatus for drawing sheet glass, the comb in ation with a working chamber for containingr a. mass ofmolten glass, means for maintaining the temperature of two oppositely disposed areas of the molten mass 1n said chamber at a degree below that of the main body of the molten mass, means for drawing a sheet of glass from said molten mass, the edge portions of the sheet bef ing drawn from said areas of lower temperature, supplemental drawin means acting on the edge portions of the s eet, and means accomplished by for cooling said supplemental edge-drawing heated to a higher degree of ten'iperatnre than at' two several points or areas thereof, means for drawing the .central portion of the sheet of glass from said main body of the molten mass and means located above said points or areas of lower temperature for drawing the edge' portions of the sheet, and means for cooling said edge-drawing means.

23. The improvement in the art of glass working, which consists in drawing a sheet of glass from a mass of molten glass whose side portions are ot' a different temperature than the middle or intermediate Portion, and sin'inltaneonsly applying more drawing power tov one portion of the sheet thanto the other, said additional drawing power being appliedthrongh cooled instrumentaliti'es. x

Q4. In an apparatus for drawingv sheet glass, the combination of a receptacle for containing molten glass, means for drawing a sheet of glass therefrom, the means for drawing the central portion of the sheet being separate and independent from the meansfor drawing the edge-portions of the sheet, 'de-Vices for driving-the drawing means for the central portion of the sheet at a rate of speed di'lfering from that of the rate ofspeed at which the edge drawing`- means are driven, and means for cooling the edge drawing means.

In an apparatus for drawing sheet glass from a receptacle containing molten glass having two several areas'of a rela tively lower degree of temperature than the main body of the molten mass, the combination of n'ieans for drawing the sheet oi glass 'from said receptacle said means comprising edge-drawing rolls located above and in close proximity to the molten mass at thhd edges of the sheet and above said areas.y and means for drawing the central portion of the sheet separvagte and indei dent from the edge-drawing rolls, and devices for cooling theedge-drawing rolls.

In testimony whereof the `petitioner has signed this specification.

v [L.S.] THE--LI'BBEY-OWENS vSHEEI GLASS U0.,

By ARTHUR E. FOWLE,

Treasurer, Attest Cnas. H. CLEMETSAN,

Secretary.

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