CA1124525A - Method and apparatus for shaping glass sheets by roll forming - Google Patents

Abstract

METHOD AND APPARATUS FOR SHAPING GLASS SHEETS BY ROLL FORMING

Abstract of the Disclosure This invention relates to shaping glass sheets by roll forming to either simple or complex curvatures about a single axis of bending or to compound curvatures comprising components of curvature about mutually perpendicular axes of bending by a controlled, repeatable program of roll forming without causing the glass sheets to stop their forward movement during their shaping. The apparatus used to perform this process has a minimum of moving parts, thus minimizing maintenance problems and reducing down time for maintenance and repair.
In a variation of this invention, shaped solid members such as successive rotating shaping rolls of predetermined contour of a first configuration engage a heat-softened glass sheet to impart a preliminary curvature different from the final curvature to be imparted to the glass followed by imparting a final curvature significantly different from the first configuration by cooling the opposite glass sheet surfaces at sig-nificantly different cooling rates during the imposition of a temper thereto.

Description

Bac~carour~d of the Invention 1. Field of the Invention This is a divisional of application Serial ~o. 314,953 filed Octo~er 13, 1978.
~~ The present invention relates generally ~o the production of shaped, te~pered sheers of glass and, more particularly, to an improved meehod of and apparatus for shaping-and heat ereating rela~ively thin glass sheets.
Shaped glass sheets are widely used as side windo~s in vehicles Sucn as aueomobiles or che like and, eo be suitable for suoh application, . .... :, ~. . ..

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flat glass sheets must be shaped to precisely defined curvatures dictated by the sha~e and ou~line of the frames defining the window openings int~
which ~he glass side windows are installed. It is also important that the side windows meet stringent optical requirements and ehat the windows be free of optical defects ~hat would tend to interfere with ~he clear viewing therethrough in their viewing area. During fabrication, glass sheets in-tended for use as shaped windows in venicles are subjected to thermal treatment to temper the glass for strengthening ~he same and increaslng the resistance of the shaped window to damage resulting from impact.
The co~mercial production of shaped glass sheets for such pur-poses commonly includes heating flat sheets to the softening point of the glass, sh~ping the heatet sheets to a desired curvature and then cooling the bent sheets in a controlled manner to a temperature below the annea~ing range of the glass. To promote efficient and large scale production, discrete glass sheets are conventionally heated, bent and cooled while being moved continuously along a~fixed path and successively through a heating section, a roll forming section, a quenching section and a cooling section. To achieve satisfactory te~per, the temperature of the glass sheet must be above a pred~termined minimum level so a~s to maintain the core or interior thereof above a deformation temperature upon being ex- -posed initially to the quenching medium at the quenching section. The residual heat remaining in glass sheets of previous commercial thicknesses, such as those having nominal thicknesses ranging from 4.5 millimeters to 6 millimeters, is generally sufficient after shaping for immediate ad-vancement ~o the ~empering area and exposure to the quenching medium Thus, the heat initially imparted to a relatively thick glass sheet to bring it to proper temperature for shaping can also be u~ilized in the ~3.~ 5~5 ~inal he~t treating operation However, within the last several years, considerable emphasis has been placed on the use of thinner and thin~er glass sheets for auto-mobile side windows as a means of reducing overall weight of the autos as a means to obtain better fuel mileage. This has posed problems in shaping and tempering, due to t~e lesser ability of the thinner sheets to retain heat and the aforementioned conventional process of bending and treating glass sheets does not lend itself to the processing of these relatively thin sheets, such as those having nominal thicknesses ranging from less than 3 millimeters to 4 millimeters (90 mils to 160 mils).
As the thiekness of the glass decreases~ the rate of heat loss increases ~ . . ...
and the heat initially imparted to such thin shee~s is quickly dissipated upon leaving the heating atmosphere of the furnace and during the relatively cool bending cycle. Attempts to solve these problems by initially over-heating the thin glass sheets have not been successful because of the consequent loss of control of the glass shaping process and the de-gradation of the surface quality of the finished glass as a result of heac stains, roll ripple distortion, and the imposition of roll mar1~s in the surface of the heat-softened glass sheet.
Consequently, roll orming has been developed as a technique for shaping and tempering glass sheets at a high production rate. ~ne of the benefits of the roll forming process is the rapid removal of each individual glass sheet from the heating section or furnace through the shaping section and into the quenching section. In the roll forming ~ethod, glass sheets are conveyed without stopping through heating, shaping, and tempering sections along high speed glass s~eet conveyor means to drastically reduce the time needed to traverse the distance between the e~Yit of the 5 :~

heating section or furnace to the tempering or quenching section to a minimum, 2referably under 5 seconds. Under such circumstances, thin giass sheets can be tempered by quenching withoue imparting such a high initial tcmperature at the furnace that shape control and control of surface quality is lost as a consequence of insuring that the temperature at the core of each glass sheet does not cool to below the ~inimum tem-perature needed on arrival at the quenching section to assure adequate temper.
Quenching or tempering medium is applied against the op~osite majOr surfaces of the shaped glass sheets. In the past, a movable gate ~as sometimes provided to mini~ize back flow of quenching medium into the shaping sPction. This involved the inclusion of a moving element whose ~ovement must be correlated with the movement of individual glass shee~s from a shaping section to a quenching section.
~ In roll for~ing as practiced in the prior art, either ~ con- _ tinuous glass ribbon or a series of discrete glass sheets is heated to or above the deformation temperature of the glass ana passed in a con-tinuous motion through one or more shaping stations where the shape of the glass is changed from a flat configuration to a shaped configuration.
Shaping individual glass sheets by roll forming, particularly those of non-rectangular shape having one or both longitudinal side edges e~tending obliquely of the path of glass sheet movement, is more difficult to per-form than roll for~ing a con~inuaus ribbon, because individual glass sheets have leading edges as well as side edges that are prone to be distorted by a high speed shaping operation, whereas only the side edges oE a con- -tinuous ribbon are more prone to distortion than the main body o~ the glass.

~L~.2~25 Glass she~ts have be~l warped or distorted into different con-figurations, that is, from flat to curved or from curved to flat by ~ither differentially hea~ing or differentially cooling the opposite glass sheet surfaces. Shaped glass sheets have been subjected to ~ slight pressure differenti31 to maintain t~e shaped glass sheets in frictional enga8ement with shaped rotating conveyor rolls that propel shaped glass sneets th~ough a quenching section where chilling ~edium is applied to the heated shaped glass sheets rapidly enough to impart a temper thereto.
~owever, thin glass sheets distorted solely by differential heating and/or diferential cooling have been known to develop an "oil canning" effect in which the thin distorted glass sheet flexes uncontrollably between metas~able states of opposite flexure compared ~t~-a fl~t sheet.
The history of prior art attempts to shape glass sheets con-tinuously without causing the glass sheets to stop for the shaping step so as to obtain as h~gh a produc~ion rate of shaped glass sheets as pos-sible and the problems associated wi~h shaping thin glass sheets by dif-ferential heating and/or differential cooling will be understood better in the light of a description of the prior art thst follows.

2. Description of the Prior ~rt ~ lany patents have been issued on roll forming.
Drak~ U.S. Patent 2,348,887 n~ves heated glass sheets between a pa~r of aligned pressure rolls 32 and 33 of cylindrical configuration which fo~ce the bottom surfaces of the glass sheets to ride over a series of spaced bending rolls 31 of cylindrical configuration mounted for sotation along spaced li~es that extend t~ansversely of a curYed path corresponding to the shape desired for the bent glass sheet~. The shapes impasted to ~he ~oving glass sheets are limited to cylindrical curva~ures of uniform radius about an axis transverse to the path of glass movement.
Jamnik 3,226,21q and 3,284,182 and Jamnik and Pelzl 3,245,771 and

3,248,198(al1 U.S. patents)fonm a oontinuous ri~bon of glass into cross-sectional contours of U-shaped confi~uration by passing the ribbon bet~een consecutive pairs of rolls comprising complementary upper and lower forming rolls of gradually increasing severity of shape. These patents shape con~inuous ribbons of glass rather than discrete glass sheets.

Humphreys U.S. patent 3,420,650 foLms a contLnuous ribbon of U~shaped oon-figuration by firs~ tensioning the flst ribbon to adiust it~ width while hot and then shaping the hot, tensioned ribbon to a ~-shaped contour. This patent trea~s a eantiDuous ribbon rather than discrete vlass sheets.

Bogrets U.S. patent 3,820,969 moves forming elements toward one another to make profiled articles from a ribbon of hot moving glass. The glass is shaped rela~ive to an axis extending along the path of glass movement. The movement of a forming elemen~ must be correlated with the ~ovement of the other forming elemPnt and with the glass ~ovement for this system to operate effectively.
Ritter et al U.S. patent 3,881,906 sags heated gl3ss sheets ~o intenmediat~

shapes of progressively increasing curvature transverse to ~heir path of movement by conveying said heated glass sheets on successive, contoured, ro~ating, conveyor rolls of increasing transverse curvaeure en route to a shaping station. The entire weight of a ~ransversely extending leading element of the glass is borne entirely along the side edge portions of the glass as it transfers from one contoured forming roll to the De~t.
Consequently~ the lateral edges kink away from the overall curvature desired and it is necessary to stop each partially shaped glass sheet at a shaping station where its shaping is completed by the inertia graYity method ~hich invol~es the use of a shaping mold that moves in Qn upward vercical direction tr nsverse to both the glass movement path and ~he axes of rota~ion of ~he contoured ~olls to engage ~he glass sheet margin ~hile the glass sheet fo~ard moy~mene is stopped. This patent also provides a moving gate between the shaping station and the qu~nching station to limlt back flow of quenching medlum from the quenching station to the shaping station. Therefore, this patented apparatus ~ust coordi~ate the movement of a sh~ping mold and a gate with the glass sheet movement.
Nedelec 3,545,951, Bezombes 3,801,298 and ~,832,153 and Ho~f et al 3,831,23q(all U.5~ Fatents~shape ~Vin~ ~lass. sheets ~etween shaFed conVexor rolls that support the lo~er surface o~ m~ving heat-softened glass sheets and a movable upper shaping member of compiement~ary configuration. The apparatus of these patents provides a family of simple curves about a single axis transverse to the path of glass sheet movement. These patents require the shaped conveyor rolls to rotate between different orientations from a flat -glass supporting position ts a shaped glass supporti~g position. The change in orientations must be correlated Wit~l glass sheet movement to obtain de-sired results.
Frank 3,701,644; 3,856,499; 3,871,855, 3,891,420; 3,929,441, 3,934,996;
3,992,181 and 4,043,783, and Knapp 3,869,269 ~11 U.S. patent~ disclose roll forming apparatus capable of shaping a succession of discrete moving glass sheets to either simple shapes provided with one component of shape about either an axis extending longitudinally of the path of glass sheet move-~en~ or about an axis extending transversely thereof or compound shapes involving various combinations of two components conforming to said simple shapes. In addition; the roll forming apparatus of this group of patents is capable of shaping glass sheets to either simple os compound shapes ~L~ .2 ~5.~5 involving non-unifor~ radii of curvature.
This last group of patents provides different inventions in~
corporaeed in the most sophisticated system ~or shaping continuously moving glass sheets eo various shapes at ~he highest rates of production attained prior to the present invention. However, even though this Iast group of patents provided highest production rates and the greatest varie~y of simple and compound shapes for glass sheets ever attained, the apparatus comprised ~ovable parts whose move~ent between spaced apart positions on opposite sides of a paeh of movement provided by conveyor rolls for glass sheets and glass engaging positions to one side of said conveyor rolls had to be correlated~with the glass sheet move~ent between the movable parts. This correlation required constant monitoring and frequent adjustment of moving partS. In addition, it was necessary to spend considerable time for set up and adjustment of the apparatus when production patterns were changed to insure that the movements of the rotating shaping rolls toward and away fro~ one another correlate properly with the movement oe discrete glass sheets therebetween.
~ any pa~ents have also issued on thermal warpage of trea~ed glass sheets. These patents use differential heating or cooling or a combination of differential heating and differential cooling against the opposite surfaces or the glass sheet to snape the glass to a different shape from its original shape.
U. S. Patent No. 3,223,499 to Cypher and Davidson differentially heats ~he glass sheee while conveyed on a roller hearth to induce an upward warp, then ehe heat differential is reduced to reduce the warp wnile con- -tinuing to heat the sheet. The heated sheet may be supporeed on a roller heareh or a gas hearth.

U. S. Patent No. 3,245,772 to Cypher and Davidson covers thermal warping bv differential heating while conveying glass sheets on a }0112r convevor e~tending through a furnace.
U. S. Patent No. 3,Z62,768 to Carson temporarily warps a selected edge portion of glass sheet away from an outline mold to which it has been shaped by gravi~y sagging by differentially applying cooling fluid against the opposite glass sheet surfaces so as to ensure better cooling of the warped edge portion of the shaped glass s~eet supported on the outline mold for bending.
U. S. Patent No~ 3,332.,761 to Fredley and Sleighter discloses the application of cold air upward at a rate sufficient to provide glass ~ . . ....
sheet support while annealing glass sheets in spaced relation over a gas hearth.
U. S. Patent No. 3,342,573 to Fredley and Sleighter- discloses supplying a support gas at different pressures at different parts of a gas hearth.
U. S. Patent No. 3,372,016 to Rahrig, O'Connell and Ferguson discloses differentially heating a glass sheet to bow the sheet upward a~d then heating from below only to tend to remove the warp that is formed by the initial differential heating.
U. S. Patent No. 3,396,000 to Carson, Ferguson~ Ritter and ~more discloses quenching opposite surfaces of the glass sheet ac preselected different rates to warp a flat sheet to a desired cur~ature.
U. S. Patent ~o. 3,497~340 to Dennison and Rigby discloses a diferential rapid cooling of opposite sides of glass sheets through the tempering temperature range to cool the faster cooling side through the temperature tempering rznge then reducing che faster cooLing rate to maintain

4~ 5 that side cooled at a lesser cooling rate at a tempera~ure high enough to maintain the glass she~ts at a fir~t configuration and ~hen continuing cooling un~il the sheets are no longer deformable through ~iscous flcw whereby a second configuration forms in the glass s~ee~.
U. S. Patent No. 3,522,029 to Carson and Ritter- discloses shaping _ glass sh~ets by differ~nciall~ cooling one surface from ehe ce~tral area eo an ~dge area and also shaping gl2s5 sheets ~y differential cooling ~f the opposite surfaces during movement ~long a mul~l~le speed conveyor.
U. S. Patent ~o. 4,028,086 ~o Rahrig a~d Revells disc~oses passing glass sheets thr~ugh a quench area where a pressure differential be~ween _ the top and bottom surfaces is applied to force the~ glass sheet upward against upper conveyor rolls and to ~arp or shape the shee~ by cooling its bottom surfacP f~ster than its top surface.
None of the patents disclose shaping a glass sheet by r~l} for~ing to one con~iguration and changing the configuration by differential cooling.

Summary of t~e_ Invention The invention of the present divisional, in one aspect-, provïdes apparatus for shaping and tempering glass sheets to a shape comprising a longitudinal component of curvature having a substantially constant radius of curvature comprising a roll orming section and a quenching section disposed in end to end relation, a series of longitudinally spaced forming rolLs each extending transversely of a path of movement of substantially constant radius o~ curvature In said roll forming section, a series of additional shaped rolls longi-tudinally spaced rom one another, each extending transversely of a continuation of said path of movement of substantially const~nt radius of curvature in said quenching section, means for supplying quenching medium to said quenching section, means for delivering discrete glass sheets at a temperature sufficient for shaping to said roll forming section, means for rigidly supporting said rolls along said path of movement in said roll forming section and along said continuation of said path in said quenching section and means for rotating said rolls whereby said discrete glass sheets develop a longitudinal component of curvature of substantially constant radius of curvature with minimum deviation in surface smoothness as t~ey are shaped and tempered.
In-a further aspect said rolls in said roll forming section and in said quenching section have a con~non transversely shaped con~iguration, whereby said heat-softened glass sheets develop a complex shape incorporating a transverse component of curvature in addition to said longitudinal component of curvature.
In a still further aspect said series of forming rolls comprises forrning rolls extending transversely of an upstrearn portion of said roll forrning section and additional forming rolls in a downstream portion of said roll forming section, said addïtional forrning rolls in said downstrearn portion comprising a series of lower forming rolls each extending transversely of said path of substantially constant radius of curvature, a series of upper forming rolls including a roll vertically aligned with each of said lower forming rolls, and means for rigidly supporting each of said upper forming rolls iIl fixed vertically spaced relation to its corresponding lower formlng roll at a distance slightly rnore than the thickness of glass sheets conveyed between said upper and lower forrning rolls.
According to a specific embodiment of the present invention to be used with or without a differential cooling arrangement, the apparatus for shaping glass sheets by the roll forming method comprises means to deliver heat-softened glass sheets to a roll forming section one sheet at ~.Z~5Z5 a time. The means comprises a tunnel-type.furnace extending from an entrance to an exit and a roller conveyor comprising a piurality of transversely e~tending rolls of cylindrical configuration longitudinally spaced from one anoeher from upstream of said furnace entrance ~o beyond said.furnace exit to provide a plurality of spaced, aligned lines of suoport defining an essentially straight path of movement for a series of said glass sheets through said furnace and comprising means to deliver one glass sheet at a time to a roll forming section.
The roll forming section has tWO portions. Its first or upstream .
portion comprises a roller conveyor e~tension e~tending i~ an obliquely downward direction from adjacent the furnace exit and comprising a first series of transversely extending conveyor rolls of cylindrical configuration longitudinally spaced from one another along a common upper tangential plane defining a straight.line e~tending obliquely downward relative to said.straight path~in a downstream direction from said exit, and a second series o~ shaped rotating forming rolls, each of wnich is located inter-~ediate a different adjacent pair of~said first series of conveyor rolls.
In the first portion of the roll forming section of the speciric embodiment, each ~orming roll of said second series h~s a given transversely curved configuration. Each succeeding forming roll of said second series in the firs~ portion of said roll forming section is mounted for rOtatioQ
on a shaft, and preferably co~prises a curved shaping surface of concave elevation Each forming roll in the first portion of the roll forming sec~ion has a curved configuration conforming Co the given transverse curvature of concave elevation formed by each of the other forming rolls.
Each shaft that supports a forming roll included in the second series is rigidly supported in bearing housings. Each of the latter is fi~ed in a unique position relative to a roll support frame so as to support rigidly each successive forming roll in such a position thae the curved upper surfa~e of each successive forming roll has a larger portion of its said curved configuration disposed at a higher elevation relative to the obliquely e~tending straig~t line defined by the common upper tangential plane of the first series of said conveyor OEtension rolls of said roller conveyor extension.
The combination of alternate forming rolls and conveyor e~tensiQn rolls so disposed enables the first portion of the roll forming section to support successive incremen~s of continuously moving glass sheets an straight lines of support at their eransverse center portions that gradually diminish in transverse length and on shaped lines of support that gradually increase in length from the side edges to ehe center` transversely of the path taken by the glass sheets thraugh the roll forming section. Supporting ?art of the mass of the glass sheet on the central portion of the conveyor e~-tension rolls of the firse series while periodically increased eranSve~se end portions are supported by rotating forming rolls or ehe second series conerols the glass sheet shaping i~ a manner that reduces edge kinking as the ~lat, heat-softened glass sheets are transferred from the furnace to gradually develop a shape transverse to their path of movement that is related to the transverse curvature common to said rotating forming rolls according to a controlled program of shaDing without requiring movable forming rolls whos~
movement transverse to the glass sheet requires coordination with the moving glass sheets.
In the method perfor~ed by this apparatus, each glass sheet in the series is heated to at least its deformation temperature. The shaping operation begins with the longitudinal increment o~ the leading edge thereof supported aross its entire width on a flat rotating surface of the first ,._~. !
4~i25 .
e~tension conveyor roll of the fixst series. Tllen said leading edge increment moves over a first rotating forming roll of the second series, which-supports the leading edge increment at its transverse e~tremities only on its shaped rota~ing surface. Alternately, the leading edge increment is supported on successively shorter lines of support extending transversely outward from its transverse center portion and~successively lcnger curved lines o~ support along its ~ransversely opposite side edge portions until ehe lines of support extending inward from its transverse e~tremities merge to form at least one continuous `~urved iine of su?port e~tending transversely of t~e path of glass shee~ movement and the trans- ~
verse center support of flat configuration is eliminated altogether Each longitudiDal increment of the glass sheet in turn follows a program of ro~ating roll support such t~at at the end of the first portion of the roll forming section an entire transverse dimension of a moving glass sheet is .~
supported by a rot~ting roll of curved configuration. This gradual transfer of the glass sheet increment by increment from support by cylindrical~rolls oi the first series to support by rolls of curved configuration of the~second series improves the control of the shap~ng operation and reduces the tendency of the glass sheet to kink at its transverse edges.
According to a specific embodi~ent of the present invention, the roll for~ing section also includes a second portion (or downstream portion), which second portion includes a third set of additional lower forming roils includin~ for~ing rolls having the same transverse configuration as those in said second series disposed downstream of the aforesaid first portion or said roll forming section. A fourth see of upper forming rolls is included in the second portion of the roll forming section. Each upper forming roll of the fourth series is aligned with a different one of said additional lower ~ -14-: .

forming rolls of t~e third series, These aligned forming rolls of the third and fourth series are rigidly mounted for rotation in pairs of corresponding formi~g rolls spaced vertically apart a distance slightly greater than the thickness of the shaped glass sheets.
The upper forming rolls of the fourth series have shapes that are complementaL to the shapes of the additional lower forming rolls of the third series. In this manner, the shape that is imparted to the glass sheets moving along the first por~ion of the roll forming section is main-tained within limits defined by the vertical spaces bet~een the corresponding upper and lo~er forming rolls of the sets of forming rolls. To accomplish this feature, the vertical space bet~een each corresponding upper for~ing .. . ...
roll and lower forming roll is greater tha~ the glass sheet thick~ess by an amount that is within the tolerance permitted by the customer for the shaped glass sheets.
The apparatus also inc}udes a quenching section and a cooling section, ~
Additional conveyor rolls having transverse curva~ures approximating those of the second and third series of lower forming rolls are adjustably mounted to provide a smooth continuation of the path along which the second a~d third series of forming rolls are disposed. The additiona} conveyor rolls are lo-cated in the upsrream portion of the que~ching section to at least a positiOn wichin the quenchino sec~ion ~here the glass sneet sur~aces are set.
When the apparatus is used to perform a simple bend about an axis parallel to the path of movement for the glass sheets through the furnace, all of the transverselv shaped rolls of the second series in the first portion of said forming section, the lo~er additianal forming rolls of the third series of aligned fon~ing rolls in Che second portion of said roll forming section and the additional conveyor rolls in the upstream portion of the quenching section are mountcd in a straight hori~ontal line.
I~en glass sheets are to be sha~ed to a compound curvature, Che forming rolls of the second series are interspersed among the conveyor rolls of the first series in the ~irst portion of the roll forming section along a do ~ ~ardly curved first portion of a path of concave elevation~ _ Thls downwardly curved path is correlated with a longitudinal component of shape to be imparted to the glass sheecs transverse to the transverse co~ponen~ imparted by the.transverse curvature of the forming rolls. The lotier ,orminV rolls of the third series of aligned for~ing rolls and the additional conveyor rolls in the upstream portion of the quenching section are mounted along a smoo~h continuation of said curved path of concave ele-vation. The rigid support of the aforesaid sl~aped rolls in the roiI forming section and in the upstream portion of the quenching section provides spaced rolling support a~ spaced lines transverse to a s~ooth continuing longitudinal curve that imparts and maintains a component of longitudinal curvature until the glass suriaces are cooled and hardened sufficiently to p}eserve the smoothness~of the glass surfaces in the upstream portion of the quenching section.
In both embodi~ents, t~e close spacing between the aligned rolls of the third and ~ourth series provides an effective barrier to "blow-back"
to~ard the roll for~inv section of quenchinv or te~pering ~edium applied against the opposite major surfaces of the roll. for~ed glass sheets in the quenching section. This barrier is even more effective in case the additional lower forming rolls are supported in closely spaced relation below upper forming rolls of complementary curvacure that are disposed along longitudinally -curved lines along the path of glass movement as is the case when the forming rolls are adjusted for shaping glass sheets about two ~utually s perpendicuLar axes of curvature as is charac~eris~ic of a compound or compLic~ted bend. Furthermore, this aspec~ or this inven~ion pro-tects the glass sheets rom e~posure to blasts of cempering fluid pre~aturely by providing barrier means comprising ele~ents that remain fixed in preselected positions and need not be moved in synchronism with the movement or glass sneets into the quenching section.
The forming rolls have diameters that vary considerzbly over their axial lengths. It is preferable that they be segmented into rela-tively sho~ lengths. Only selected segments are rigidly fixed to the shaft on which each forming roll i.s mounted to rotate there~ith and the remaining segments are~freely rotatable ~ith respect to the shafts. This fea~ure reduces rub marks that are developed in t~e hot glass sheets when the glass surIaces are so hot and soft that mar~ing due to large differences i~ peripheral speeds of different portions of the rotating forming rolls causes roll ~arks. Segmenting the forming rolls to relatively short axial lengths and providing minimum frictional resistance between the free running segments and the shafts results in minimum difference in peripheral speed along the axial lengeh of each forming roll segment Hence, segmented forming rolls develop less surface damage in the hot glass than continuous shaped rolls. Of course, when the glass surface is relatively cold and hard, it is not necessary to segment the rotating rolls of curved config--uration as the relatively hard glass surface is less prone to develop surface damage than hot glass.
I~ is desirable to lessen thc distance between adjacen~ shaped forming rolls once ~he glass has assumed a shape appro~imating the curved configuration of the forming rolls in the first portion of the roll for~ing section. According to a fur~her embodimen~ of ~his invention, certain alterna~e aligned pairs of segmented upper and additionQl lower forming rolls omit segmen~s of large dia~eters co permit closer spacing between adjacent shaped for~ing rolls in the direction of glass sheet movement.
The remaining segments are longitudinallY aligned with the segmen~s of forming rolls that are provided uith all the shzped segments needed to develop a substantially continuous shaped con~iguration of desired curva-~ure along the axial length of the shaped orming rolls.
The segments tha't remain in the additional lower forming rolls of curved configuration of concave transverse curvature are spaced rrom the ends thereor, whereas the aligned upper forming rolls of co~plementary convex transverse curvature have certain segments spaced from the a~ial center portion thereof remaining, The omission of end segments at the lateral extremities of certain additional lower forming rolls oE the third series permits the glass sheet transverse edges to sag somewhat to compensate for a ninor amounr of kink that cannot be avoided completely at the trans- _ verse extremities of the glass even with the controlled support provided by the combination of cYlindrically shaped additional conveyor rolls and concavely curved for~ing rolls in the first portion of the forming section.
In this embodiment of the invention, the last two sets of aligned shaped forming rolls in the downs~ream end of the second portion of the roLl for~ing section have all the shaped seg~en~s included to provide substantially continuous rotating shaping surfaces of complemelltary curva-ture to assure that each glass sheet arrives at the quenching section in the desire,d transverse shape and also to insure that the last pair of sets of aligned continuous rolls provide protection against substantial blow~ _ back of cool quenching ~edium from the qu;enching section back to the first portion of the roil fonning section where the upper major surfaces ~ . Z ~ 5 of the glass shee~s are exposed to the ambient atmosphere and would be subjec~ to premature cooling that would spoil the temper.
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: The various elements.of the preSeDt invention wlll be understood more clearly in~the light of a descr~ption of a specific:embodiment of this:
:'' ;' ' invention which follows.

Descri~tion of the Drawin~s In the drawi~gs whlch for~ part o} the description of the speciric embodiment of this. invention,. and wherein like reference numbers are ap-plied to like structural elements, : FIG 1 is a schematic longitudinal assembly view of a specific embodiment of the present invention showing the relative arrangement of conveyor rolls and forming rolIs of a roll forming section of apparatus conL-orming ro:the pres2nt invention and its rela~ion to a heating furnace and quenching and cooling sections;
FIG. 2 is an enlarged longitudinal side view of rol]. forming apparatus as in the present invention with the conveyor extension shown out of the operative position depicted in ~IG. 1 to show the details oE
certain structural elements of the roll forming section ~ore clearly;
' ' ' .

FIG. 3 is an enlar~ed plan view of the first portion and of the third series of for~ing rolls of the second portion of roll forming ap-paratus conforming to the enlarged view of FIG. 2 with certain structural elements omitted eo avoid confusion;
FIGS. 4 to 17 show schematic vies~s taken across different in- ~
cremen~s of the roil for~ing section showing how a glass sheet is supparted by various combinations of forming rolls and conveyor rolls as it is con-veyed through a roll forming section during the snaping of a glass sheet;
FIG. 13 is a transverse elevational view of the upstream portion of a quenching sec~ion where the shaped gIass is chilled rapidly to impart a temper and supported in a manner to avoid losing one or both components of curvature;
FIG. 14 is a plan view across a series of adjacent rows of nozzles showing their arrange~ent in one po~tion of the quenching section forming part of the apparatus illustrating the present invention;
FIG. lS is a view similar to FIG. 13 taken across a cooling section beyo~d the quenchi~g section showing the arrangem~nt of upper and~
lower cooling nozzles of the slot: type and the arrangement of conveyor rolls for transporting the shaped and tempered glass sheet for further cooling by said s.lot nozzles;
FIG. 16 is a iongitudinal end view of a second portion o~ a second embodiment of a roll forming section wherein glass sheets are shaped to a transverselY curved cylindrical bend about an axis e~tending longitudinallY of the path of glass travel;
FIG. 17 is a transverse sectional view taken along the lines 17-17 of FIG. 16; and FIG. 18 is a transverse sectional view taken along the lines 18-18 of FIG. 16, ~ ~.f~ 5 Description of tllP Spec~fic Embodiment Referring to the drawings, a specific emDodiment of this in-vention incorporates a tunnel-type furnace lO followed bv a roll forming section 12 compos~d of tuo portions followed bv a quenching section 14 and a cooli~g section 15 disposed in c}osely spaced end to end relation to one another~ ~he furnace includes an orienting and alignmen~ ~eans adjacent the furnace e~it and within the furnace. A typical orienting and ali~nment means that may be used is found in U. S. Patent ~o. 3,701,643 to Fran~.
A conveyor is pro~ided f or the furnace and the first portion of ~he Toll forming section, The conveyor comprises a plurality of furnace conveyor rolls 16, each extending transv~rsely of the furnace in longitudinally spaced relation along the le~gth of the furnace to provide transversely e~ending, longitudinally spaced rotating lines of support for propelling glass sheets through the furnace, a pair of ~ransfer rolls 18, a pivot roll _ 20 and a first series of additional conveyor rolls 22 ~oun~ed for rotational support on bea~ing housings 23 and 24 supported on a pair of roll iDtercon-nected longitudinal side ~embers 26 and 28 that pivot in unison relative to the pivot roll 20. The rolls 16, 18, 20 and 22 are cylindrical shafts.
Extensions of the shafts for pivot roll 20 and the first series of additionai conveyor rol~s 22 terminate to one transverse side of the conveyor in chain-driven sprockets 30 which permit the first series of ad-ditional conveyor rolls 22 to rotate in unison rel~tive to the longitudlnal side members 26 and 28 to which they are interconnected to form a frame-like 6tructure that pivots about a hori20n~al axis defined by the pivot roll 20 at the ups~ream end of the pivotable frame-like structure.

5.2~

~ transverse plate 32 interconnects longitudinal side ~embers 26 and 28 ~nd is attached to elevator means 34 in the form of a pistOn and rod whose upper end is pivota~ly mounted to a clevis 35 fixed to the bottom of ths trans~erse plate 32. As an alternative, a screw type jack mav be used for the el~vator means 34. The entire frame-like _.
structure including its rolls 20 and 22 and the interconnected longitudinal side me~bers 26 and 28 is pivotably supported a~out a pivot axis defined by pivot roll 20 for movem'ent between the upper inoperative or storage position shown in FIG. 2 and the oblique operati~e orientation depicted in FIG. 1.
The frame-like structure that supports the additional ConveyOr rolls 22 and pivot roll 20 is snown oriented in a substantiallY horizontal position in FIG. 2 to facilitate illustration of the structure of an illustrative embodiment. In the operating position for perfor~ing the method for wnich the apparatus of the present invention is designed to _ perform, the pivotable Era~e-like structure comprising members 26 and 28 and the rolls 20 and 22 mounted thereto is pivoted into the obliquely downward orientation depicted in FI~. 1. Thus, the pivot roll 20 and the additional conveyor-rolls 22~ are supported to define an obliquely downwardly extending path beyond the transfer rolls 18 at the furnace e.xi~. The o~l~' uely downward orien~ation ol the additior~al conveyor rolls 22 relative to the pivo~ roll 20 is an important feature in obtaining rapid and controlled curvature or gLass sheets from a flat to a curved configuration during their transfer from the furnace 10 to the quenching section 14.
The roll for~ing section 12 comprises a plurality of forming rolls n~ounted on rotatable shafts 40. Each shaft is driven from a common .25 drive mechanism (not shown~ and eYtends through a pair of ~earing brac~ets 4Z and 44. The lattèr are rigidly mounted to a rigid support Erame 46 having longitudinally e~tending horizoutal support members 47 and 48 interconnected by transverse channel-like supports 49. The latter are mounted on a base SO to whic~ is attached means for supporting the elevator mechanism 34.
The transverse channel-like supports 49 are adapted to receive the fork of a fork lift truck. I~hene~er a gross pattern change is re-quired, the roll for~ing section is disconnected from the rest of the equipment (par~icularly the roll drive mechanism) and carried away by a fork lift truck. Another roll forming section for a different pattern is a~a;lable for substitutio~ by use of anothèr ~ork lift truck. It is unde~stood that a fork lift truck is described by way of example and anq suitable carrying or lifting mechanism may b~ used. The substituted roll forming section comprises rigidl-y supported rolls of a differe~t transverse config~ration and/or a differenc line of support along a curved line having a diEferen~ longitudinal radius of curvature from that of the replacement roll forming section or along a straight li~e.
The bearing brackets 42 and 44 are transversely aligned with one another and are spaced longitudinally relative to one another so that the e:~tensions of the shafts of the additional conve~or rolls 22 can pivot with the pivotable frame-like table to an obliquely downward orientation ~herein the successive additional conveyor rolls 22 are disposed at successively lower elevations relative to the elevations provided by the for~ing rolls supported on the shaEts 40. Successive forming }olls S3, 55, 57, 59, 61, 63 and 65 comprising a second series of rolls and additional ~orming rolls 67, 69, 71, 73, 75, and 77 co~prising a third _~3_ ~.2~ii2~

series of ~olls in the roll forming section are arranged in spaced relation dcwnstream of one another.
Each of the forming rolls 53 ehrough 77 is composed of shaped segments having a transverse curvature of concave elevation transverse to the path defined by the first series of additional conveyor rolls 2Z, Each segment is composed of a m2terial having a low t&e~lal conductivity, a low coefficient of thermal expansion over a wide range of temperat~-res and a chemical COmpOSitiOu that does not react chemically with glass. In addi~ion, the ~aterial selected for the segments is durable over said wide ~emperature range and one t~at makes the segments readily shaped or machined to curved COntOurS An asbestos cement of alumino-silica COmpositiQn sold by Jo~ns Manville under the trademark of IR~NSITE has been found to be most suitable for the segmented rolls of roll forming apparatus userul in the present invention.
Each of the aaditional co~veyor rolls ?~ of the first series is disposed approximately midway between adjacent forming rolls of the second series of rolls. The additional conveyor rolls 22, the pivot roll 20 and the transfer rol.ls 18 are of relatively small diameter and are com-posed of thin metal shafts (preferablY stainless steel) covered with a fiber glass sleeve or tape or wi~h a hard ceramic coating.
ach bearing ~racket 42 and 44 and its corresponding nori~oncal sup?ort member 47 and 48 of the rigid suppor~ frame 46 is provided with aligned apertures and is spaced above the respective support member by a d~s~ance determined by a shim 78 disposed bet~e~n each horizo~al support member 47 and 48 and its corresponding bearing bracket 42 and 44 and pro-vided with aligned apertures to receive attacl~ment bolts and nuts. By providing shims 78 of different thickness along the length of che roll z~

forming section 12, the for~ing rolls 53 to 77 are supported at spaced ~ransverse lines aiong a smooth ~rcuate path of substantially constant radius of curvature correlated with the longitudinal component of shape desired for a glass sheet eo be shaoed to a compound shape.
If it is desired to impart a simple bend to the glass sheets com- _ prising a curvature in a direction transverse to the path of glass sheet movement, the thic~ness of the shims 78 supporting each of the bearing brackets 42 and 44 are equal (as depicted in the embodiment of FIGS~ 16 to 18) so as to space each of the bearing brackets a uniform distance abFve the respective horizon~al suppor~ ~embers 47 and h8 of the rigid supporc fra~e.
The forming section 12 also comprises a plurality of vertical~
posts 80 interconnecting a pair of upp~r horizontal longitudlnally extending support members 81 T~ith a corresponding pair of louer horizontal ~embers 82.
~ach of the upper members 81 supports a mounting bracket 84 in spaced re-lation below the upper longitudinal support ~embers 81 by upper shims 85 of different thicknesses compleme~tary to the thickness of each of the corresponding shims 78. The mounting brackets 84 support shafts 86 of a fourth series of rDlls ~upper forming rolls 87, 89, 91, 93, 95 and 97) in alignment over the shafts 40 of the corresponding third series of forming rolls 67 to 77 in the second portion or the roll forming sectio~. The u?per forming rolls 87 to 97 of the fourth series have a conve~ outer contour that is complementary co the concave outer contour of the corres-ponding Lower forming rolls 67 to 77 of the third series, ~ he thicknesses of the shims 85 ~ounted to the members 82 are inversely related to the thickness of the shi~s 78 supporting the brackets 44 so that lower formi~g rolls 67, 69, 71, 73, 75 and 77 of the third series of rolls, which are directly opposite upper forming rolls 87, 89~ 91, 93, 95 and 97 of the fourth series of rolls, ase supported in uniformly spaced relation below the correspo~ding upper forming rolls at a spacing sligntly more than the thickness of glass sheets passi~g ~here-between.
The dri~ng n~h~Mism for rotating the forming rolls is essentially thatpr~vided in ~he roll ~orming aFparatus of U.S. Patent No. 3,891,420 bo Frank. Independent drives are Erovided for rotating the additional conveyor rolls 22 of the first series OI rolls independently of the drives for the forming rolls 53 to 65 of the second series,for the lower forming rolls 67 to 77 of the third series and for the upper forming rolls 87 to 97 of the fourth series. The four series of rolls are rotated on straight shafts at speeds d~signed to convey each glass sheet by friction through the roll for~ing section 12 as promptly as possible.
The uniformity Df shaping each sheet treated will be understood from the repetitive program of operation show~ in FI~S. 4 to 12. In par-ticular,FIGS. 4 to 10 disclose the program of operation of the arrangement of the respective forming rolls 53 through 65 inclusive of the second series of rolls with respect to the additional conveyor rolls 2~ of the Elrst s2ries as a representative glass sheet traverses the first por~ion ~f the roll forming section.
As each longitudinal increment of the representative glass sheet G passes over the rotating pivot roll 20, the latter momentarily engages the entire wid~h of the sheet and propels ~he sheet downstream. A short distance dow~stream, only the longitudinal side edges of the giass sheet increment are momentarily engaged by the tr~versely curved concave .25i surface of the first for~ing roll 53. This is shown in FIG. 4. In the meantime, a succeeding longicudinal increment is l~omentarily supported across the transverse dimension of the sheet by rotating pivot roll 20, Sin~e eacn or the succeeding additional conveqor rolls 22 of _ the first series of rolls is at a lower elevation than its i~mediately preceding additional conveyor rolL, and since the forming rolls of said second series of forming rolls in the ~irst portion of the roll forming section 12 are dispos2d aIong an arcuat~ path of concave elevation that is no~ as stee~ in decl~ning elevation as the obliquely downward e~tending straight path defined by the spaced additional rotating conveyor rclls 22, it will be obvi.ous that gradually the glass sheet is transferred by longi-tudinal increments fro~ momentary support on straight lines of support across the entire transverse dimension to a co~bination of momentary supports comprising curved lines of momentary support of gradually in-creasing le~gth along an increasing portion or its longitudinal side edge portions extending transversely inward thereof and gradually decreasing straight lines of momentary support extending gradually decreasing dista~ces transversely of its centrally disposed area.
~ en the longltudinal increment of .he glass shee~ G reaches the Lirst additional conve70r roll 22, it -s ~omentarily supported along a substanti~l portion of its transverse dimension along its central portion on the first additional rotating conveyor roll 22. A short tistance down-stream therefrom a sli~htly longer transverse extremity portion at each side edge of the glass sheet is mamentarily supported on ~he concavely curved rotating surface of the second forming roll 55 than was supported upstream on the first Eorming roll 53, as seen in FIG. 5. The second additlonal conve~or roll ~2 then provides a shorter straight line of momen~zry suDport along a smaller central portion at a short distance do~ns~ream from rocating ~orming roll 55, and shortly afterward, rotating forming roll 57 provides a transversely curved support in momentary rolling engagement for a slig~tly larger transverse end portion at each transverselv opposite end portion of the glass sheet increment than was ~ -provided by ~orming roll 55, as seen in FIG. 6.
The succeeding additional rota~ing conveyor roll 22 momentarily suDpor~s a still slightly shorter central transverse portion of the glass sneet increment than the preceding additional conveyor roll 22. FIG. 7 shows how the rotating forsing roll 59 provides longer curved lines of momentary support along the opposite transverse e.~tremities for the glass sheet increment ~tnan forming roll 57. After a still shorter momentary straight line transverse ce~tral support by the additional rotating con-veyor rol]. bet~een forming rolls 59 and 61~ rotating forming roll 61 ?rovides curved line momentaxy supports ror larger transverse extremity portions or the glass sheet incre~ent than forming roll 59. FIG, 8 shows that still longer curved lines of momentary transverse support are pro-vided by rotating fo~ming roll 61 than that provided by rotating forming roll 59 with corresponding shorter straight line momentary cencral suppor~ -pro~ided by ehe additional conveyor roll therebet~een, By the time the glass sheet reaches the additional conveyor roll 22 between formi.ng roll 61 and formlng roll 63, only a small central por-tion is momentarily supported on a straighe line of support by the trans-versely extending additional conveyor roll 22. FIG. 9 shows the increment o~ ehe almost completely shaped glass sheet almost entirely supported momentarily along transversely inward curved lines of support formed on 5.~

ro~ating forminO roll 68 with its transverse center portion just out of contact with roll 63. By the time the glass sheet increment reaches rotating forming roll 65, the entire transverse dimension of the glass sheec G is ~omentarily supported on the transversely curved shaping surfa.e of forming roll 65 after it has passed above the last additional conveyor roll 22 betueen rotacing forming rolls 63 and 65 completely out of contact with the last additional conveyor roll 22. This arrangement is shown in FIG. 10.
It is understood that the number of shaped rolls in the first portion of the roll forming section illustrated is exemplary, and the number may be incre2sed or decreased depend~ing on ~any factors such as size and thickness of glass sheets processed, complexity of bend, etc.
Also, the do~ward slope of the common upper tangent of additional conveyor rolls 22 may be adjusted in vie~ of these factors.
Since a considerable portion of the centraL area of the glass sheet is si~ultaneously supported momentarily while the forming rolls begin to engage the glass sheets momentarily at their transverse end portions in the first portion of the roll forming section, the amount of edge kink im-parted to the glass sheets is controlled to a considerable extent compared to roll fo m ing practices of the prior art where the entire mass of the glass sheet ~-as supported initially on the tLansverse edge portions rollin~
over the curved shaping rolls.
As the shaped glass sheet enters the second por~ion or the forming section, its entire width is supported momentarily on the first additional rotacing forming roll 67 of Che third serics in closely spaced relation below upper forming roll 87 of the fourth series as depicted in rIG. 11.

~ 2~ S

~ihen the glass sheet reaches the position between upper forming roll $9 and lower forming roll 69, its central portion is supported momentarily on ~he central segments of lower forming roll 69 with its transverse edge portions unsupported from below in close relation below the trans-verse outer segments of upper forming roll 89 as depicted in FIG. 12.
The shaped glass sheet increments are supported momentarily o~ shaped lolJer forming rolls 71 to 77 of the third series in closely spaced re-lation below correspondimg upper forming rolls 91 to 97 of the fourth series as the glass shee~ traverses the second ?ortion of the forming section 12.
The shaped glass sheet is thus supported momentarily by increments in c~e second portion of the forming section on additional shaped rotating forming rolls 67, 69, 71, 73, 7S and 77 in closely spaced~relation below upper rotating forming rolls 87, 89, 91, 93, 95 and 97 of complement~ry curvature disposed above-the^glass sheet in vertical alignment over the corresponding additional forming rolls 67 to 77. The transverse curvature of concave elevation of the additional forming rolls 67 to 77 of the third series of rolls is the same transverse curvature as that common to the immediately preceding shaping rolls 53 to 65 of the second series o~ rolls in the first portion of ehe shaping sec~ion.
~ 1 the shaping rolls are segmented in both the first and second por~ions of the shaping section. Such segmenting reduces the severity and even thc incidence of roll marks co~pared to marks obtained using continuous orming rolls.
One purpose of providing upper and lower shaping rolls of comple-mentary curvature in the second portion of the roll forming scction is to s maintain che shape of the glass that is imparted by successive momentary supports by th~ first and second series of rolls in the first half of the forming section 12 within tolerance limits. It has been found that it is unnecessary co provide all the segmencs of each forming roll and it has also been found to be desirable to maintain the forming rolls of the third and fourth series in a closer longitudinally spaced relation to one another than is possible if all the forming rolls of the third and fourth serics had all their segments. Therefore~ alternate forming,rolls in the second portion of the forming section 12, such as rolls 69 and 89 are provided with only certain s~aller diamet~r Segmen~S so as to permit the glass shape impart~d by forming rolls 53 to 65 of the seco~d series ~: - . ; ..
of rolls to be maintained uithin desired tolerance. For e~ample, the upper forming rolls 89 and 93 are provided without centrally disposed larger diameter segments and the transverse outer segments of the lower forming rolls 69 and 33 are omitted.
~ he opposing forming, rolls 67 and 87 are of camplementarv curva-ture and are disposed at a distance reIative to one another slightly more than the thickness of glass sheets undergoing processing. This is to limit any distortion in shape of the shaped glass sheet as it passes through the second portion of the forming station 12. The same is true of the spacing between forming rolls 65 and 89, betw~en forming rolls 71 and 91, between forming rolls 73 and 93, between forming rolls 75 and 95, and becween forming rolls 77 and 97. Also, the downstream pair of forming ralls 77 and 97 effectively reduce the back flow of quenching mcdium for thc quenching section bv virtue of their close vertical spacing. _ The forming rolls in the first portio~ of the forming sect:ion 12 are mo-mtcd on shafts 7 inches ~18 centimetcrs) apart. Removing che largest ~LJ~oi ~

diameter segments from alternate f~rming rolls in the second portion permits their arrangement on shafts only 6 inches (15 centimeters) apart or less.
The closer spacing helps maintain the longitudinal shape component imr parted to glass sheets conveyed over rotating forming rolls arranged along a curved path.
Another benefit of having the largest diamerer segments remov2d from certain additional lower forming rolls is that the transverse ex-tremities of each increment are unsupported for ewo relatively long time intervals compared to the shorter time intervals between momentary adjacent rotating suppor~s pro~ided centrally by the central segments. Therefore, the transverse end portions of the glass sheets are free to sag somewhat in relation to their supported center portions. These momentary opportuni-ties for transverse edge sagging co~pensate for any minimal edge kink that is imparted onto the glass sheets even though the transverse edges do not bear the entire mass of the glass sheets. Furthermore, there 2re two -co~plete lower forming rol~s 75 and,~77 that support the glass sheet in-crements across their entire width downstream of rolls 69 and 73 that permit increased durarion of transverse edge sag. Rolls 75 and 77 are immediately before the entrance to the quenching section. Therefore, neither edge kink nor e~cessive edge sag ls a problem for glass sheets entering the quenching section after such a prog~am or su~port in the second porti~n.
Beyond the forming section 12 there is a quenching section 14.
In the quenching section 14, 2 succession oE grooved conveyor rolls 98 transversely shaped in conca~e elevation similar to forming rolls 53 to 77 (e~cept for rolls 69 and 73) is provided. The conveyor rolls 98 thus ~2~i`2~

pr~vide additional cur~ed supports for the shaped glass sheets delivered to the quenching section 14. The quenching section 14 is depicted in cross section in FIG. 13 and in plan i~ FIG. 14 and a further cooling section 15 is depicted in FIG. 15. The shaped conveyor rolls 98 in the first portion of the quenching section 14 are provided ~Tith one quarter inch deep grooves one quarter inch wide spaced along the axial length of the quench conveyor roll to permit the lower surface of each shaped glass sheet to be esposed to blasts of air from nozzles g9 disposed inter-mediate adjacent shaped con~eyor rolls 98.
The conveyor rolls 98 in at least the ups~ream portion of ~he quenching section 15 are adjustably mounted on straig~t shafts disposed along a continuation of'the curved path o~ constant radius provided by the forming rolls af the second and third series of rolls. The arcuate path taken by the shaped glass sheets is uninterrupted from the roll, forming section inta ehe upstream portion of the quenching section until a location is reached:where tne surfaces of each conveyed glass,sheet are sufficiently hard to retain its shape.wheu tilted onto the re~ainder of the conveyor extending horizonLally at the same elevation as the rolls in the furnace 10.
In the first~ portion of the quenching section 14, round nozzles 99 are provided in transversely extending rows located both above and below the shaped conveyor rolls 98 to impar; air blasts according to a pattern agains~ the upper and lower surfaces of glass sheets moving along the shaped, grooved rolls sa. Each of the nozzles 99 COmmuniCateS with an upper or lower plenum chamber 100. The amount each of the round nozzles 99 extends from its associated plenum chamber 100 is determined bY an arc having an averzge radius of curvature con'templated for the ~ransverse curva-tures of the sheets processed. Apparatus designed to process glass sheets having ~ran~verse curvatures of 40 inchcs (l neter) ~o 75 inches (1.9 meterS) have the nozzles in e~ch row terminate in a curved line from an arc of a circle of approximately 60 inch ~1.5 meters) radius.
The arc is or concave elevation. This arrangement spaces the end of each nozzle ~9 relative to the wall of the associared plenum chamber lO0 that faces a glass sheet surface so that the nozzle to glass dis-eance is substantially uniform across the traasverse dimension of the sheet even ~hen the sheet has a radius of curvature different than 60 incnes (1.5 ~eters).
~ ez~s 101 (see FIGS. 13 and 15) is provided for supporting ana adjustingrthe vertical posieions of angles supporting bearing housings for the grooved rolls 98 so that the curved path for~ed by forming rolls 53 to 77 can be continued uninterrupted into the quenching section 14 along rolls 98. Additional means 102 is provided to support and adjust the vertical positions of the upper and lower plenum chambers 100 so as eo facilitate any repair and maintenance work and eo provide gross ad~ustmen of nozzle to glass distance. Such adjustmene means are well known in the art and need ~ot be further discussed at this point.
The individual round nozzles 99 in the lllustrative embodiment are arranged in 48 transversely extending ro~s longitudlnally spaced 4 inches (10 centimeters) a~art. The nozzles in each row of the firse siY
ro~s are approximately .622 inches (1.6 centimeters) ir. diameter and the nozzles 99 in the remaining 42 rows are one-half inch (1.3 centimeters) in diameter. The nozzles in each row are spaced approximately 1.5 inches (3.8 centimetors) center co center along the lengeh of each row e~tending eransverse to the glass sheet path. The tows extend transverse to the path of glass movement through the quenching section and adjacent rows of round nozzles are disposed in offset relation to the rows of the ~-~ 2~5~

immediately~ preceding and the immediately succeeding row of nozzles.
Upper and bottom rows face one anothcr in nozzle to nozzle alignment.
~ dequate temper has been obtained from plenum pressures of l~
ounces per square inch (S000 pascals) ~or the upper plenums and 8 ounces per square inch (3300 pascals) for the lower plenums in processing glass -sheets 5/32 inch (4 millimetcss) thick. A slight net downward pressure is helpful in kee~ing thin glass shee~s in frictional relation to the shaped rota~ir.g conveyor rolls in the quenching section so as to move the glass sheets uniformly through the quenching section 14 and avoid "chattering" of the glass sheets as they are conveyed along the conveyor.
.~t ~he cooling section 15, additional plenum chambers lO0 are provided, each terminating in slot-type~nozzlès 103, having apertured open ends facing the path taken by the glass sheets and transversely shaped to conform generally to the shape defined by the ~nds of the transverse rows of nozzles wnich approximates the shape desired for the glass sheet. A
cross sectional view of the end portion of the cooling section shawing how the nozzles 103 are arrangea relative to the conveyor rolls is depicted in FIG. 15. In the illustrative embodiment, transversely~ extending slots 3/16 inch (4.7 millimeters) wide are longitudinally spaced 8 inches (20 centimeters) apart.
So-callea doughnu~ rolls 104, which co~orise central shafts 105 of 3/4 i~ch (1.9 centimeters) diameter and a pair of doughnut shaped members 106 about 2 inches (5 centi~eters) in diameter are mounted on the central shafts in axially s~aced relation in adjustable fixed positions along the shaf~s so as to suppor~ shaped glass sheets in spaced reiation to ~he shafts. Shaf~s 105 exterld transversely approxi~ately midway between adjacent slot nozzles. Such arrangemencs are well known in the glass tempering art and specific illustrative operating condltiol-s are disclosed to providc a full disclosure of the present invention.
It ~ill be seen from the foregoing description that a series of glass sheets, after bei~g conveyed through a furnace, is delivered at a deformatiOn temperature to a roll forming section where glass sheet increments are alternately supported momentarily on curved forming rolls and flat additional conveyor rolls so as to gradually impart a transverse curvature thereto. In addition, if the shims supporting the bearing brac~ets on wnich the forming roll shafts are mounted are of different thic~nesses, and the adjust~enr means 101 for the quenching rolls 98 are properly adjusted, then the succession of forming rolls and quench conveyor rolls in the upstrea~ portion of the quenching section are disposed along a smoothly curved path. The forming rolls of the second series impress a longitudinal curvature on the glass sheet moving from roll to roll. As the glass~sheets pass through the second portion of the roll forming section, the longitudinal shape impressed by the first series of rolls in the first portion is mai~tained with edge kinking minimized by larger intervals be-t~een certa~ n successive edge supports and the glass sheets are then sub-jected -to i~mediate quenching wnile supported on shaped quench conveyor rolls 98 along a continuation of the smoothly curved line of longitudinal curva~ure 3etween blasts of air disposed agains~ the upper and lower sur-'aces of the shaped glass sheets. During initial eYposure to quench air at the quenching section the glass sheets are first supported on shaped rotating quench conveyor rolls 98 that e~tend in a furthe e~tnnsion of said curved path, and then supported in a horizontal line parallel ~o ~he horizontal line of the conveyor rolls 16 in the furnace when the glass sur-faces have hardened sufficiently to permit their tilting to a hori20ntal plane of support.
Flat glass sheets have been shaped and tempered at a rate o over 800 sheets per hour using this apparatus. This has been accomplished without requiring any movement of the forming rolls except for rotation.
Glass sheets are conveyed at about 700 inches per minute (18 meters per minute) through the furnace and 1400 inches per minute (36 meters per ~inute) through the forming section and the quenching section, Glass sheets are heated to attain a temperature in the range of approximately 1150~F. to 1 20~F. (620C. to 660C,) at the furnace exit and are cooled naturally for about 4 seconds while traversing the forming section which occupies the space between the furnace exit and the first row or noæzles in the ~uencning section, In a typical production operation using the equlpment described to produce over 800 pieces per hour, air is supplied at a no~inal flow o~
about 1000 standard cubic feet per minute per square foot (5 cubic meters per second per square meter) of plenum at a totaI pressure of 20 ounces per square inch (8600 pascals) to the upper surfacP and 18 ounces per square inch (7700 pascals) to the lower surface through the first 5iX rows of round nozzles, then at a nominal flow of about 500 standard cubic feet per minute pe~ square foot (2,5 cu'oic meters per second per square ~ter) of plenum at a pressure or 21 ounces per square inch (9000 pascals) ag insc the upper surrace and 18 ounces per square inch of ?lenum (7700 pascals) agains~
ehe lower surface through the ne~t lS rows~ ~he temper is well es~ablished at chis poinc.
Additional air blasts are applied at a nominal flow or about 400 standard cub.ic fee~ per minute per square foot (2 cuoic mecers per second per square ~leter) of plenum at a pressure of 20 ounces per square inch 4~i25 (~600 pascals) against the upper surface and a pressure of 18 ounces per square inch (7700 pascals) agains~ the lower surface through the remai~ing 24 rows of round nozzles. An additional flow at the nominal rate of 200 standard cubic feet per minut2 per square ~oot (1 cubic meter per second per square ~eter) or plenum is then applied ~hrough the slot nozzles at a pressure of 8 ~o 10 ounces per square inch (3400 to 4300 pascals) against the opposite surfaces to concinue cooling the glass sheets in the cooling section 15.
Glass shee~s having a nominal thickness of 5/32 inch (4 millimeters) 90 treated did not have an "oil canning" problem and met all the requirements for a break pattern needed to meet the automotive code. For e~a~ple, the largest frag~ent of fractured tempered glass cannot ~eigh more ~han 4.25 grams or it fails to meet the code. Typical break patterns show ~ grams to 2.5 grams weight for the largest particle.
When flat glass sheets are heated to above their distortion temperature and then cooled.rapidly to below their straln point, the glass is tempered. When the glass sheets are cooled so that their opposite sur-faces cool at di~ferent times to below the strain point, the tempered sheets are distorted. However, in thin glass sheets, the warped glass is likely to fl~:~ between metastable states even when the opposite surfaces are chilled at drastically different rates. This tendency to flex has not been observed with glass sheets that are first shaped by roll ~orming ~o a curved configuration and then altered in shape by differential cooling fro~
above the derormation temperature to below the strain point of the glass.
~ typical produceion operation uses the equipment described to shape glass sheets to one configuration by roll forming using forming 5:~5 rolls having a transverse radius of curvature or 75 inches (1.9 meters~
and with their shaf.s arranged along a longitudinally curved path having a radius of 3600 inches (93 meters) (including quench conveyor rolls at the upstream portion of the que~ching section) in a smoo~h continuous curved path followed by differential cooLing. In this operation, air is supplied at a plenum pressure of ~0 ounces per square inch ~8600 pascals) ;o the upper surface and 5 ounces per square inch (2200 pascals) to the lower surIace through che first si~ ro~s of round nozæles to impart a temper and distort the glass sheet to a configuration sig~ificantly dif-feren~ from the first configuration. Further ~ooling is accomplished ~ith air supplied at a plenum pressure of 21 ounces per square inch (9000 -pascals) agaius~ the upper surface aad 18 ounces per square inch of plenum (7700 pascals) againsc the lower surface through the ne~t 18 rows as the glass sheet is conveyed rapidly between said nozzles. Additional air blas~s are applied at a plenum pressure of 20 ounces per square inch (8600 pascals) against the upper surface and a pressure of 18 ounces per square inch (7700 pascals) against the lower su~face as the shaped, tempered glass sheet is conveyed berueen the remaining 24 pairs of rows of upper and lower nozzles of round cross-s~ction. An additional flow of air is then applied through the slot no7zles at a plenum pressur~ of 8 to 10 ounces per square inch ~3Loo to 4300 pasc21s) againsc the op~osite .surfaces ~o con~inue cooiing the glass sheets.
Glass sheets having a nominal thickness of 3tl6 inch (5 millimeters) so treated met all the reauirements ~or a break pattern of the automo~ive code, being consideraoly less than 2 grams. No "oil canning" problems were noted. Furthermore, glass sheets shaped to a first configura~ion by 4~

passing over rotating forming rolls shaped to psovide a 75 inch ~1.9 meters) r~dius of currature transverse to the path of movement about an axis parallel to the path of movement and arranged along a sweep, line having a radius of curvature of 3600 inches (93 meters) along the path of ~ovement were changed in shape as a result of the differential cooling treatment described previously eo develop a cu~vature having a 69 inch (l.75 meters) ~raverse radi.us of curvature about an axis ex-tending longitudinally o~ the path of glass mo~ement and a 720 inch (1~
meters) lonoitudinal radius of curvature abouc an axis ex~2nding traversely of the path of glass movement.
In the above run, glass sheets having a 20 inch (50 centimeter) dimension traverse to the path of movement and a 28 inch (70 centimeter) dimension alo~g the path or glass sheet movement and a thickness of 3/16 inch (5 millimeters~ had their tra~sverse depth of sag increased by 5 miIs (.13 milli~eters) and their longitudinal depth of sag increased by 11 mils (.28 ~illimeters) as a result of the significant cooling differen~ial of the~opposite surfaces.
In the~above runs, the glass sheets were shaped to a given first eonfiguration of concave elevation and then chilled more rapidlY at their upper major surfaces than their lower maior surfaces. Such treatment re- -duce~ the radius of curvature of said glass sheets so treated.
The present invention contemplates adjusting the absoluee as ~eLl as the relative upward and downward cooLing races by controlling relative plenu~ pressures. Thus, a single conriguration of rota~ing forming rolls of one traverse cur-Jature arranged along a swee~ line of a predetermined longitudinal curvature may be used to impart a first com~
pound configuration to the glass sheets desired to be shaped to any one z~ .

or several different configurations. Different f~nal configurations c~n be ootained fro~ a common first configuration by providing different arrangements of upper and lower plenum pressures that provide different cooling rates in the quenching section. Simple experimentation based on how much a glass sheet deviates fro~ ulti~ate curvacure (that is, whether it develops too much sag or too little sag after the correction of the first configuration) can "fine-tune" an adiustment Generally, increasing the excess of upper plenum pressure relative to a lower plenum pressure or decreasi~g the defioiency of lower plenum pressure relative to an upper plenum pressure increases the sag and reduces the radius of curvature.
On the other hand, decreasing the excess of upper plenum pressure or de-creasing the deficiency of lower plenum.pr~ssur~.decreases the sag and increases the radius of curvature of concavely shaped sheets.
FIGS. 16 to 18 show variations or certain features of the first embodiment of the present invention. For e~ample, i~ the alternate e~bodiment, all of the sharts 40 that rotatably support additional lower forming rolls 67 to 77 of the third series of rolls are supported equal vertical distances above the lower longitudinal side members 82 by using shims 78 of equal height. The ro~atable forming rolls 53 to 65 of the second series of rolls in the first portion (not shown in FIG. 16) are also supported on snafcs 40 (not shown) at the same level by using cor-responding shims 78 of equal ehickness to space the second series or rolls a uniform distance over the horizontal support members 47 and 48 inscead of using shims of different thicknesses tO provide spacings of d fferent distances as illustrated in FIGS. 1 and 2. Such an arrangement produces a cylindrical bend or a bend of non-uniform radius of curvature about an axis e~cenaing along che path or glass movemenc.

--' 1--;

~ nother variation shown in ~he embodiment of FIGS. l6 to 18 is the replacement of upper shi~s 85 with open vertical adjustment means each co~prising a pair of externally threaded rods 185 rigidly attached at their bottom ends ~a a corresponding mounting bracket ~4 and extending thro~gh one of many apertures in the upper horizontal longitudinally extending members 81. An adjust~enc nut 186 is ehreaded about the e~-ternally threaded rod on each side of the me~ber 81 and suitable loc~
nuts are provided to abut the adjustment nuts 186. Such a construction facilitates adjust~ent of spacing between corresponding upper and lower rolls of ~he third and fourth series or removal of a single upper forming roll when such maintenance is needed.
The prsviously described embodiments relate to method and ap-paratus for shaping glass sheets from a flat to various curved configurations that incorporate at least one component of curvature that is concave i~
elevation. It is also within the gist o~ the present invention to change the~sh pe of~ glass sheets fro~ a Elat to a curved configuration that in-cludes at least one component of curvature~ that is convex in elevation.
This latter co~vex curvature componen~may be co~bined with a second com-ponent chat is either convex or concave in elevation or essentially flat.
In all instances, the forming rolls, the conveyor rolls and the quenching rolls are rigidly suoported in apparatus for producing these aleernate snapes.
For eYample, to p~oduce a transverse curve of conve~ elevation, the roll for~ing section of the first embodiment is modified to provide, in combination with the first series of addi~ionaL conveyor rolls ~ of cylindrical configuration that are rigidly supported in a desired longi-tudinally oblique path, a second series of rigidly supported rolls of convex transverse co~figuration. In this embodiment, the third series of rigidly supported rolls (~he lower forming rolls in the second portion of the roll forming SeCtiQn) are convex in transverse elevation and the fourth series of rigidly suppor~ed rolls (the upper forming rolls aligned above the third series o~ rolls) have transverse configurations that are concave in transverse elevation and complementary to the transverse con-figurations of the lower forming rolls in the third series. In addition, the fourth series of rolls are closely spaced over the corresponding rolls in the third series, particularly the downstream pair F~sthermore? in this alternative emoodiment, ~he quench rolls in the upstream portion of the quenching section have a transverse eleva~ional configuration of convex eleva~ion.
~ hen it is intended to develop a ~ransverse curvature of conve~
elevation in glass sheets, the first series of conveyor rolls is tilted downward as in the first e~bodiment, thereby e~posing each longitudinal increment of a heat-sof~ened glass sheet to aIternate support by a roll of cylindrical configura~ion on progressively iesser lengths of transversely extendi~g-straight lines of support and progressively greater lengths of transversely e~tending curved lines of support of convex elevation until the heat-softened glass shee~ is supported at longi~udi~ally spaced lines of su~por~ having a transverseiy exlending convex elevaeion. The upper .~or~ing zolls o~ concave e1evation are rigidl~ supported in closely spaced relation over the corresponaing lower for~ing rolls of convex eleva~ion of comr~lemerl~ary cuzvature so as to provide one or more barriers at the downs~ream end of the roll forn~ing section to iuhibit the backward flo~
of quenching medium to the upstream portion of the roll forming section as in the first embodiment.

`Z~ .

In order to provide a longitudinal component of curvature of conve~ elevation, the second and chird series of rolls and the quench rolls in the upstrea~ portion of the quenching section are arranged in longitudinally spaced relation along a longitudinal path of conve~
elevation or substantially constant radius af curvature. The transverse shape of the forming rolls of the second and third series arranged along the longitudinal ~ath of convex elevation of substan~ially constant radius of curvature are either all conve~ly curved in transverse elevation or all concavely curved in transverse elevation or all cylindrically shaped The quench rolls in the upstream portion of the quenching section are si~i~arly shaped in transverse elevation.
In all instances, after the glass sheets have their surfaces hardened by e~posure to the blasts of tempering medium in the upstream portion of the quenching section, the shaped glass sheets can continue on a longitudinal path through the quenching and cooling sections that departs from the longitudinally curved path o~ convex elevation. ~owever, as is the case with longitudinal paths o concave~elevation, it is necessary to transport the glass sheets from forming rolls to forming rolls to quench rolls along a longitudi~ally curved path of substantially constant radius of curvature untll such a location within the quenching section that the glass sur~ace is sufficiently hard to enable the glass to transfer to additional auenching roLls disposed along a longicudinal pa~h that depar~s from the constant radius of curvature without damaging the glass surf ce.
The use of roll forming apparatus containing a mini~um of .,.oVi'Qg 2ar,s has resulted in a more uniform shape imparted to each sheet of any given production pattern and has resulted in high speed mass production. In addition, time needed for repair and maintenance and to ~s changc the apparatus to a different pattern has been minimized by the prese~t invention The form of the invention shown and described in this disclosure represents an illustrative preferred embodi~ent and certai~ modifications thereof. It is understood that other changes can be made by providing various subcombinations of elements of the illus~rative embodiments~ such as providing cylindrically shaped forming rolls disposed with quench conveyor rolls of cylindrical shape along a longitudinally e~tending curved pa~h of substantially constant radius of curvature to enhance the uniformity of shape of a longitudinally extending co~ponent of curvature, or providing rigidly supported upper and lower forming rolls closely spaced to one another immediately upstream of a quench m g section to retard blow back and eo control glass sheet shaping regardless of whether the shape imparted to the glass sheets comprises only a traverse component o~
curvature, only a longitudinal component of curvature or a comDination of said components, for exa~ple, without departing fro~ the gist of the invention as defined by the claimed subject matter which follows

Claims (3)

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

1. Apparatus for shaping and tempering glass sheets to a shape comprising a longitudinal component of curvature having a substantially constant radius of curvature comprising a roll forming section and a quenching section disposed in end to end relation, a series of longitudinally spaced forming rolls each extending transversely of a path of movement of substantially constant radius of curvature in said roll forming section, a series of additional shaped rolls longitudinally spaced from one another, each extending transversely of a continuation of said path of movement of substantially constant radius of curvature in said quenching section, means for supplying quenching medium to said quenching section, means for delivering discrete glass sheets at temperature sufficient for shaping to said roll forming section, means for rigidly supporting said rolls along said path of movement in said roll forming section and along said continuation of said path in said quenching section and means for rotating said rolls whereby said discrete glass sheets develop a longitudinal component of curvature of substantially constant radius of curvature with minimum deviation in surface smoothness as they are shaped and tempered.

2. Apparatus as in claim 1, wherein said rolls in said roll forming section and in said quenching section have a common transversely shaped configuration, whereby said heat-softened glass sheets develop a complex shape incorporating a transverse component of curvature in addition to said longitudinal component of curvature.

3. Apparatus as in claim 1, wherein said series of forming rolls comprises forming rolls extending transversely of an upstream portion of said roll forming section and additional forming rolls in a downstream portion of said roll forming section, said additional forming rolls in said downstream portion comprising a series of lower forming rolls each extending transversely of said path of substantially constant radius of curvature, a series of upper forming rolls including a roll vertically aligned with each of said lower forming rolls, and means for rigidly supporting each. of said upper forming rolls in fixed vertically spaced relation to its corresponding lower-forming roll at a distance slightly more than the thickness of glass sheets conveyed between said upper and lower forming rolls.