IE40255B1 - Improvements in or relating to shaping glass sheets - Google Patents

Abstract

A glass sheet is bent by heating the sheet while supported on its lower edge in an near-vertical disposition, closing dies on to the hot sheet at a bending station, and then tilting the dies to bring the sheet to a vertical position before the dies are opened and the sheet is removed vertically for subsequent annealing or toughening, for example by quenching the hot bent glass sheet in a chilling liquid. [CA1039950A]

Description

40255 invci'I i oil relate;; to the shaping of glass r.li'M-ta in particular to the landing of glass sheets vhich ore to be subsequently toughened or. anncnlcd and u.'jfcd in the manufacture of windows for vehicles, for example Dotor vehicle windscreens and aircraft wind-cn-eons.

A glass sheet bent by the method and apparatus of tho present invention may be toughened and then used alone as a vehicle windscreen, or may be either toughened or annealed for use as one of the lamiiiates or a composite laminated glann windscreen.

It in cust.omnry to laminate two thin sheets of glass together to form a windscreen using an interlayer of transparent plastics material, for example polyvinyl-butyral. In such a windscreen both sheets may be of annealed glass or both of toughened glass and in a current propooal a laminated windscreen having a dual fracture characteristic is fabricated using a sheet of annealed glass as the outer sheet and a sheet of toughened glass as the inner sheet.

With such a windscreen visibility is retained even if the outer annealed sheet is fractured by a sharp flying stone, while the inner toughened sheet fragments rapidly when struck by the head of an occupant of the vehicle.

Usually an the manufacture of a toughened glass for a windc.-rrm the r.iieet of flat glass is first cut. to tiif :;!)•> rippropriate bo the styling of the v> 1'icle i»> v..Vich ilio windscreen is to be fittfd and the Ciil. .. or tho r.l " Obr: arc liieri po] i r.hocl to remove 40255 dc-JVctc retiultJ:g from the cutting oporation. Then tho glass is hented to a temperaturo Kuitable for bonding, during traverse through a heating furaaco v/hile suspended by tongs from an overhead conveyor which then conveys the glass between vertical bending dies which closo on to the glass sheet and bend the sheet to the desired curvature.

Thereafter the bending dies are opened and the nss is conveyed between blowing frames where the glass is toughened, or the glass is conveyed from the bonding dies through an annealing lehr when an annealed glnan sheet is required. Throughout this process the gloss is suspended from tongs which grip the upper edge of tho sheet.

In n proccsn for bending two shoots of glass which arc to have accurately matching curvature for subsequent lamination it has been customary to bend the glass by a sag-bending process in which the two sheets lying one on top of the other are placed horizontally on a sag-bending mould and then conveyed through an oven where the glass sheets are heated and sag together to the desired matching curvature.

In a more recently developed process for the toughening of glass, a sheet of flat glass cut to the desired shape is suspended by tongs in a heating furnace having an open mouth in the floor of the furnace, and when heated to bending temperature is lowered to a location between bending dies which close on to the suspended shoot r.nd bond it to a desired curvature before tho sheet is further lowered through a pro- 40255 cooling otrigo'in which cooling air ia blown on to the glrian surfnco.% followed Immediately by quenching in a quenching liquid, which may- for example be a mineral oil or a" mineral oil with a minor amount of low boiling point additive. Toluene or. carbon tetrachloride are . (suitable :ndditive3. This process ha3 been particularly effective for "toe production of high strength glass for aircraft windscreens, and bent and toughened glass of thickness 1.5 to 3 mm for use in the manufacture of laminated windscreens for motor vehicles.

Suspension of the glass sheets by means of tongs during heating and bending brings inherent problems of distortion of the glass sheet.

It has now been found that glass sheets can be heated for bending while supported mechanically in an upright position by leaning against a transient mechanical support, for example spaced rollers which are inclined at a small angle to the vertical as long as the support against which the glass leans is advancing at the same forward speed as the glass sheet itself so that no relative slipping takes place between the mcchanical support and the glass. Contact of the glass surfaces with the roller surfaces may only be over small areas of the sheet, and as the sheet is upright, gravitational loading between the glass surface and the surfaces of the rollers is minimnl so that there is a greatly reduced risk of marking of the sheet as comparod with that customary with horizontal roller support. Further since the gravitational load on any part of the sheet, particularly when it is approaching 40285 Its softening point* is kopt to a minimum, there is less v" / ' ■■■ £ - V ; : ■ . " risk ofsaggingofthe sheet and sagging of the sheet V '• Jk between adjacent rollers is packed up by the next Troller.

. Itisa main object of the present inventionlto *{' ■ ...V. ii- A. v" Another object of the invention is to provide a method and apparatus for the continuous bending and liquid quenching of glass sheets in which each sheet is maintained throughout in an upright position without the use of tongs, and after bending is lowered vertically into a tank of chilling liquid for toughening by liquid quenching.

A further object of the invention is to provide a method and apparatus by which the glass is transferred from the near vortical position in which it is supported during heating, to a vertical position for lowering vertically for subsequent thermal treatment, cither quenching in a chilling liquid, or annealing.

The invention provides a method of shaping a hot glass sheet, comprising supporting a sheet of glass on its lower edge, providing near-vertical support for one face of the sheet so that the sheet is disposed at a small angle to the vertical, advancing the sheet while so supported through a heating furnace to a shaping station, closing shaping dies on to the sheet at the shaping station and tilting the dies through an angle to bring the sheet to a vertical position, then opening the dies and removing the shaped sheet for subsequent thermal treatment. 40355 • r* . ; * - . / , / ' .. ■ ■ ?: • ' ■'$> ■ -v* ' '* ,.•> ;C Usually incarrying outthe invention tho . " . £ -V7. .•.••• • '•> ■■. ' V ' . .' shaping, surfaces areJbending dies which are closed by : -XV : . ■ • • moving a male die. having a convex surface into bending position, and supporting the hot*glass sheet against the female die which carries the sheet against the male die to bend the sheet. The tipper edge of the bent sheet is gripped when the dies have been tilted and the sheet is vertically disposed, then the dies are opened so that the bent sheet is suspended and can then be lowered vertically for subsequent thermal processing, either by annealing or by quenching in a chilling liquid to toughen the sheet.

A series of glass sheets are bent in succession, and after lowering of a bent sheet has begun tho dies are tilted back as they are opening to an inclined disposition to receive between them the next near-vertical sheet for bending.

The invention can also be employed to produce a matching pair of curved glass sheets for subsequent lamination together to produce a laminated window unit. Each sheet is heated to the same thermal condition * during its advancc through tlic heating furnace and is bent to the same desired cui-vature. Constant conditions are maintained while both sheets are heated and bent, and subsequent to bending one of the sheets is rapidly chilled to induce predetermined toughening stresses therein, and the other sheet is annealed. 40235 Glano sheets may be advnnced in succession through the heating station, bent in succession, and alternately toughened nnd ar.noaled as they are removed from the .bending ■ sthtionv; A; toughened sheet and an annealed sheet successively proauccdare^selectedforsubsequentlamination.

P 1 Thd^ihvontion a lso comprehends apparatus for • • '; • shaping a hot'glass sheet, comprising atilling enclosure containing means for supporting a hot glass sheet at-a near-vertical angle, which enclosure is formed with access means permitting a hot glass sheet to be received on the support means at said angle and to be removed vertically from the enclosure, means for tilting the enclosure between a position in which a glass sheet at said angle is received on the support means and a position in which the glass sheet is disposed for removal vertically from the enclosure, cooperating glass-engaging dies mounted in the enclosure one of which dies is constructed to advance from behind and through said support means as the dies close on to the glass sheet, and'means for engaging the glass sheet when it is between the closed dies and for removing the sheet vertically from the enclosure when the dies open.

The enclosure may be a tilting box mounted adjacent to the end of a furnace through which the glass sheets are to be conveyed in upright disposition, with a plurality of spaced-apart near-vertical rollers in the box which define, when the box is tilted, an inclined support for a hot glass ^sheet which enters tho box from the furnace.

The invention further comprehends a shaped and thermally treated glass sheet produced by the method of invention; more particularly a bent and toughened glass sheet or a bent and annealed glass sheet. -7- 40255 .An embodiment of tho invention will now be described, by wny of example, with reference to the accompanying drawings in which:-. .V . - * Figure 1 -\ is an elevation, partly in section', • of apparatus,for. operating/ttie invention •• including a loading .station for flat; . ► . \ glass sheets, a heating furnace, bending apparatus and liquid quenching apparatus, Figure 2 is a side elevation of the loading station and the inlet end of the furnace of Figure 1, partly broken away to illustrate upright support rollers and associated bottom rollers at the loading station and in the furnace, Figure 3 is a section on line III-III of Figure 2, showing the disposition of heaters in the furnace, Figure 4 is a front elevation of a carriage on which a glass sheet is supported for transportation through the furnace, Figure 5 is a section on line V-V of Figure h also illustrating the disposition of the carriage and the glass sheet relative to the upright rollers and the bottom stub rollers of the furnace, Figure 6 illustrates an arrangement of electrical heaters on one side wall of the furnace, Figure 7 shows schematically a thyristor-controlled circuit for controlling current supply to a group of heaters of Figure 6, - 8 - 40255 Figure 0 illuutml.rn nn nrx'nngoment of electricnl hepters on the opposite side wall of the furnace, Figure 9 is a more detailed view of part of Figure 1 illustrating generally : a tilting box which encloses male and female bending dies and is mounted to be tilted from an angle matching the angle of the upright rollers in the furnace to a horizontal disposition above thermal treatment apparatus through which bent glass sheets are lowered, Figure 10 is a sectional view of a flexible seal between the furnace and the tilting box, Figures 11A and "*.1B together constitute a part-sectional view of the tilting box on line XVIII-XVIII of Figure 9, Figure 12 is an end view of a rocking frame on which the tilting box is mounted, Figure 13 illustrates in detail the mounting of adjustable bottom stub rollers in the tilting box, Figure 14 is an overall view of support beams and an actuating unit for the * female bending die, Figure 15 is a partial end view of the apparatus of Figure 14, Figure 16 is a nection on line XXIII-XXIII of Figure 14, 10 15 20 25 40355 Figure 17 Figure 18 Figure . 19 Figure 20 Figure 21 Figure 22 Figure 23 Figure ?J\ Figure 25 Figure ?6 ia n plan view of tho end part of the apparatus illustrated in Figure 15» is a front elevation of the female bending die, is a schematic plan view of the die of Figure 18, is a vertical section through a support structure for the female bending die of Figures 18 and 19 showing an adjustable mounting for the die, is a detailed elevation of a clamping suspension forming part of the support structure of Figure 20, is a section on line XXIX-XXIX of Figure 20, is a more detailed schematic view of the male and female bending dies in tho tilting box as seen from the outlet end of the tilting box, is a horizontal cross section through the male die, is a front elevation of a lifting finger assembly attached to one^ bottom corner of the female bending die, is a side elevation of the lifting finjrer assembly of Figure 25, -10- 40255 •» KiKinv ."7 In n plan vli« of tho lifting finder nnot-raWy of Kigures 2'j and 26, Figuro 28 is an end elevation of actuating.. ' * &■■■' ' • ,v' ; s? mechanism fort the lifting finger y. . ■/ _|v .■ ' < •. ■' % ' ' ">'• ' 5 \assembljr of Figures 25 and i26, >, ;f Figure 29 , is a front /elevation of the actuat- •f • v ' v' '' • - • ing mechanism of Figure 28, ' •'/; " " -3"' " ' ■£ Figures 30A, 30B and 30C together form an overall view in elevation of a tong bar 10 from vhich tongs are suspended for gripping the upper edge of a glass sheet between the male and female bending dies, and of the hoist mechanism from which the tong bar 15 is suspended, Figures 31A, 31B and 31C together show: an end elevation of a part of the hoist mechanism and the tong bar suspension, po Figure 32 is a detailed front elevation of the tong bar of Figure 30, Figure 33 is a plan view of the tong bar of Figure 32, Figure 34 is an end elevation of the tong 25 bar of Figure 32, Figure 35 is a front elevation of glass sheet suspension tongs which are shown suspended in a tong gate which is fixed to the tong bar, with a sheet 30 of glass gripped betveen the tong Jaws, - 11 - 40355 Figure Is a side elevation of tho tongs of -•.t,, ' . % . , v r . / Figure 35» * ■ -s- ' .-'4: ■ . * • >f V V *• • Piguyo® sectiow on line XLIV-XLIV of '"4?\- ,•&' % ■ U -v *'• ■ * "■ ' - 4 '-|?lgur^35''^ "■ " ■ 5 1 Figure ^ 3Q §is a soctiort on line XLV-XLV of :i ■■'' • v.-'Jill/ :'$:• - Figure 39j|is a vertical section through panels v *'bf boost heaters which are located - beneath the tilting box and between 10 which a bent glass sheet is lowered for heating prior to toughening, Figure AO is a generalised sectional view through the lower part of the pit below the tilting box showing a pre-15 cooling stage and a tank of chilling liquid in more detail, Figure 41 illustrates the quench tank of Figure 40 in greater detail, Figure 42 is a side elevation illustrating 20 the construction of a scissors-lift table supporting the quench tank of Figure 40, Figure 43 is a diagrammatic hydraulic control circuit for the tilting box, the 25 bending dies and the tonp bar suspen sion system, Figure 44 is a diagrammatic pneumatic circuit for operating the tong opening mechanism, brakes on the hoist ?0 .. mechanism, and speed control of the hoist motor, - 12 - V 40288 •/ l-'igiiree 45, U6 and 47 arc circuit diagrams of % switching circuits for operating the ;» • )rarotoict'iind pneumatic circuits of - ^ ■' : V ■. 'J*- 1 ■ '■< < -'V V* Figures '43f. and- 44, V ; y , 4. • • • •$. "'£)&* '<* . <* . f' .• '-T-" • f- 5-| Figure 40 is a vicw of -tee lower part of the pit I- C showing apparatus for producing alter- •' k • ; nately.a toughened and an annealed : glass sheet, Figure 49 is a section on line LVI-LVI of Figure 48, 10 Figure 50 is an end view of part of the apparatus of Figure 48, in the direction of arrow LVII, Figure 51 is a side elevation partly in section of an alternative to the lifting finger 15 assembly of Figures 25 to 27, Figure 52 is a section of line LIX-LIX of Figure 51, and Figure 53 is a part-section on line LX-LX of Figure 51. Figure 1 illustrates the general arrangement of apparatus 20 for carrying out the invention, for heating, bending and toughening glass sheets which are conveyed through the apparatus throughout that operation in an upright disposition, that is in a near-vertical disposition during heating, end in a vertical disposition after bending and when being quenched 25 in a chilling liquid.

The furnace chamber is indicated generally at 1 and has a cross-section of rectangular form with a specially shaped floor as will be described, and is supported at an .ingle to the vortical of about 5° in a basic girder framework which 30 includes base girders 2 which are joined at their ends by -13 _ 40255 cross ginler*; 3. Ki-on tho ends of tho base * girders there extend upright Girders 4 which are ■ •at on angle of for example 5° to the vertical as more, clearly shown in; Figure. 3. The upper ends of/ the upright girders 4. are connected together ■... Vv -- -J ■ ' r. ' '* "v by cross .girdcra 5 which are inclined at an angle of about 5 below the horizontal.

^•^^The-^floor. of tho lUriiace 'is supported by cross girders 6 which extend below the lower ends of the upright girders 4 and are shaped to support the shaped floor of the furnace. The downwardly sloping step in the furnace floor which slopes towards the bottom of one side wall permits any cullet which falls to the floor to be collected at outlets near the bottom of the side walls, which outlets are closed by hinged doors.

The furnace 1 is a refractory-lined, metal structure having side walls which extend upwardly from the floor and an integral roof construction which is hung from the upper girders 5. Longitudinal girders 7 fixed along the top of the furnace provide support for gear boxes housing the upper ends of a plurality of spaced-apart, upright, near-vertical rollers 8 which define an inclined support for * sheets of glass 9 which are to be convoyed through tho furnace x for bending and subsequent liquid-quench toughening ior annealing.

The rollers 8 are asbestos-covercd or of heat- 40255 rf.siatJnK steel and arc cuch mounted nl. nn u/>g.lc of from 2° to 10° to the vortical o.g.L>°, find form part of a conveyor for tho sheets li which extends right through the furnace 1 frt>m n loading station indicated generally at 10 .to a bonding station 11. The rollers are 6.5 cm in diameter and arc spaced 19 cm apart in the fumaco. .The spacing between rollers may be up. to 30 cm in -the region of the outlet end of tho furnace whore the glass reaches its final temperature. At the inlet end of the furnace where the glass is at a low temperature, tho spacing may' be yvator, for example 30 cm or more providing there are sufficient rollers to support the whole length of the glass sheet in a stable condition.

The conveyor includes a movable support in the form of a carriage 12 on which the lower edge of the glass sheet 9 is seated, and bottom stub rollers 13 which project through spaces between tho upright rollers 8 near the bottom of those rollers both at the loading station 10 and in tho furnace 1, and driving means for advancing the carriage 12 through the furnace with the glass shoot 9 loaning against the upright rollers M.

Tho bottoir stub rollers 13, which are also of heal.-resistant stainless steel or asbestos covered, are mounted, in Liu.- embodiment'illust- 402S5 rated, at acute uncle of 50° to tho upright rollers 8.

. ' The carriage 12 is shown in more detail ■ . . ■ ■ • i> in Figures 4 and 5 and is oX V-section having M . ■ .. • 5 faces which are at an anglo to each other matching the acute angle between tho axes of the upright rollers 8 and the stub rollers 13. These faces of the carriage engage frictionally both the rollers 8 and 13* which are driven at the same io speed as will be described, so that the carriage carrying the sheet is advanced through the furnace by the frictional engagement with both the bottom rollers 13 and the upright rollers 8.

Initially, only the upper edge of the sheet 15 roots on tho surface of the upright rollers 8 but as the cheet is heated during its advance through the furnace the sheet tends to relax against the transient support for the sheet provided by the rotating surfaces of the rollers 8. - 16 - The bo 1.torn c.'U"o or tho ulin-t is seated on npecially cltaped supports on the carriage and is slightly offset 'L ' u-j ^ -i*. . ■■■ ■ ' v / , , 1 • • • '• ' ' - - • •• k-., ■ on ^tho carriage 12 from the rollor surfaces, so that a certain relaxation with deformation only below a predetermined limit can take place while ensuring that the sheet remains in its upright, disposition and that the lower edge of. the sheet does not become displaced from the carriage.

' In operation thermal conditions in the furnace are set and the timo taken by the carriage carrying the glass sheet to traverse the heating zone is also set in dependence on the glass thickncs3t the height of the glass sheet, tho angle of tho support rollers to the vertical and tho amount of offset of the lower edge of the glass sheet from the support rollers so as to achieve a predetermined temperature condition of the glass, the thermal and time settings be in/1: uuch as to permi t the gin:::: .".licet it is hen led to relax ago in::L the support roller:; only by an amount less than the maximum deformation of the glass sheet which is acceptable prior to bending. The heating of the glass sheet as it ti-averr.es the heating r.one is described in Irish Patent Application No. 398OA.

Usually the offset distance is about 2 mm to h mm and the maximum acceptable amount of deformation depends on the quality, particularly the optical quality required in the final product. In the case of plus.". sheets which are to be incorporated in vehicle windscreens, for which 17 40295 . thy optical requirements nro stringent, it may only be acceptable to permit deformation of the glass sheets up to a point in** tho initial relaxation before .the appearance of tho bulge. A bulge of up to 0.5 mm may be acceptable. •• " ^ » Where requirements are less critical a - bulge gz^ater than 0.5 mm may be permissible, for example upi to 4.0 mm.

It has been found that the near-vertical angle at which the sheet is initially supported when leaning against the rollers 8 may be in the range 2° to 10° for the heating of sheets of soda-lime-silica glass of thickness in the range 1.5 mm to 15 mm to a temperature in the range 580°C to 680°C or even 700°C which temperature range encompasses the usual temperature to which soda-lime-silica glass is heated prior to bending or toughening.

The upright, near-vertical rollers 8 are supported at their lower ends by self-aligning bearing blocks which are.carried by parallel girders which run beneath the furnace floor and are supported on the speoially shaped cross-girders 6.

The first ten upright rollers 8 of the plurality of upright rollers constitute the loading station 10, and five bottom stub rollers 13 are respectively located between alternate spaces belv/ccn the upright rollers B.

At the bending station there are horizontally disposed bending dLos 15 and 16 which are shown more particularly in Figures 9, 11A and 11B. The female die 15 is a rin^ frame die which co-operates with a male - 13 40255 die IT, having a continuous bonding surface, indicated in more.detail hi Figure 2h. The dle3 Illustrated or** rigid-, dies but articulated wirig dies wi th pivoting mechnnianT of jknown kind may be employed for bending . comply windscreen shapes. The dies are located in l '• *"?«y •" •••'■' v5-' '' ; • ' _ ; a'tilting box"17 which is a refractory, lined metal ' • Initially the box is in its tilted position and the male bending die is moved into position as the carriage carrying a glass sheet enters the tilting box and as soon as a hot glass sheet is located between the dies the female die 15 moves through the rollers 18 to press the sheet against the male die and the rocking frame is tilted to its horizontal position as bending of the sheet proceeds. During movement of the female die the glass sheet is lifted from t.ho carriage by fingers on tho female die which pass beneath the lower edge of the glass sheet and lift the short.. When the rocking frame is horizontal, a tong bar 2J carrying ^lass-gripping tonr.s 22 is lowered from a _ 20 - > 4025S t hoist mechanism indicated at ,°5 which can itself be raised and lowered.

Provision J:; made for the tongs PP. to eiigngo in recesses in the upper edges of „ the dies 15 and 16, do thut they can grip the upper edge of the glass sheet •as it is held between the bonding dies.

When the Glass sheet has been lifted from the carriage 12, the carriage is accelerated out of the tilting box on to the exit conveyor 8 before the rocking frame is rocked to its horizontal position when the dies open and the glass, now suspended vertically from the tongs, is lowered through a mouth in the bottom of the box for further treatment.

During its traverse through the furnace 1 the glass in heated to bending temperature for example 610°C at which temperature tho glass can lie satisfactorily bent and engaged by the tongs 22 without having become so soft as to endanger the finish of the glass surfaces during the bending operation.

When the bent glass is to be toughened, especially when a high strength glass is required, it is desirable to quench the glass from a higher glass temperature, e.g. GlX.)°C, and in the embodiment illustrated in Figure 1 the bent glass is reheated before it is quenched in a chilling liquid contained in a quench tank 26 which is located in a pit beneath the tilting box 17.

Just beneath the exit mouth in the bottom of the tilting box the glass passes between two banks of electric heaters 27 mounted in a pattern as illustrated facing botJi surfaces of the glass. During the passage of the 40353 pin so downwardly between theuo healers the /^Iogs at its bonding temperature, e.g. 610°C, Is heated through- ! . out its thickness to a pro-qucnching temperature nearer to tho softening.point of tho glass e.g. 680°C. The b'erit ginss inay bo lowered at uniform speed so as to maintain as near ns practically possible uniform temperature throughout tho whole glass sheet. . Alternatively the glass may be accelerated as it is lowered between the heaters' to produce in the glass a uniform temperature gradient from a high temperature at the bottom of the sheet to a lower temperature at the top of the sheet.

Such a temperature gradient may be induced in the glass sheet prior to bending by running lower sections of boaters on the furnace walls hotter than upper sections, or by locating tho lower sections of heaters in closer proximity to the glass as described with reference to Figure 3. For example the bottom of the furnace may be at 800°C, middle areas of the furnace walls at 750°C and the upper part of the furnace at 700°C. The male bending die 16, Figure 24, is then heated by means of internal heaters 511 mounted internally to have a temperature distribution matching that induced in the glass sheet by such a furnace.

Below the boost heaters 27 are two blowing boxes 28 both of which are supplied with cooling air at ambient temperature, for example about 30°C, which is projected through nozzles 29 in the boxes uniformly towards both surfaces of the cl^ss sheet. This pre-cooling of the glass surfaces nfter boost heating produces 'immediate 40255 teinpornl.ui'C grn'licnto from tho control corc to the surfaces, of. the glads. l"ho. core of the glass remains at about,the temperature achieved between tho boost h'caterp, arid the pre-cooling of the glass surfaces is 5 nuch that.while the glasstemperature is still above the strain point of the glass, the glass sheet is immediately quenched .in u chilling liquid before these temperature gradients decay.

As the glass is being lowered from the bending 10 dies tho tank 26 of chilling liquid is raised on a scissors-lift platform 30 which stands in the bottom of tho pit. The tank 26 is raised until the top of the tank i3 located just below tho bottom of tho blowing boxen J'M with l.lio surface of the chilling liquid In tho 1 'i tank at a predetermined :;mnll distance from the bottom nozzle:; 29 of tho blowing boxes. The bent glass sheet in which core-to-surface temperature gradients exist as just described is immediately quenched in the chilling liquid as it passes from the ambience of the cooling air 20 into the surface of the chilling liquid.

The chilling liquid is usually a mineral oil for example CYLREX FI-1 (Trade Mark) and may have added to it a minor proportion of a low boiling point additive for example up to 1?S by weight of toluene or carbon ?r> tetrachloride.

As the £lnss is immersed in the liquid in the tank 26 it comes to rest on a frame immersed in the tank, which frame ir» attached to the bottom one of the blowing bnxr:>. The ton,";, are opened to release the flass on to -jti the franc and after a time to permit the ^'lass to coo] - 23 - 40355 » in the liquid tho tank is lowered, the class is removed from tho frame and degreased, and the toughened glass is stackcd in a rack to complete its. cooling to ambient temperature. * In another method of operation the tank 26 is not raisdd, the bent, glass sheet comes to rest iA the frame , and remains in the frame for cooling in ambient air to produce an annealed glass sheet. Ah annealing enclosure may be moved on a horizontal track into position to receive a hot bent glass sheet.

Provision may be made for alternatively annealing and quenching sheets in succession as they are lowered from the bending dies so that successive sheets of a pair are respectively annealed and toughened. These sheets have been heated and bent under identical conditio] and have matching dimensions and are emminently suitable for laminating together in the manufacture of a laminated windscreen.

Figures 2 and 3 illustrate in more detail the construction and operation of tho loading station and the furnace.

The first ten upright rollers 8 of the conveyor constitute the loading station as illustrated at the right hand end of Figure 2. These rollers are of heat-resisting stainless steel and are nou» "red at 20 cm intervale between upper horizontal girde. * 35 and lower horizontal girders 36 which form extensions of the girder construction supporting the furnace 1.. The girders yj> and at the loading station are connected to an end.frame comprising a base girder 2 and an uprij-.liL 40255 wh 1 cli iimvl iiu-ri to the vortical at- Hit* mine auglo »»f nl»o«il. ••" a:: I.Jn* r»>I Ili ;• • mI wliit'li I:: ::ti|»|n»H«m| by r.Uru L;>. Tlie riul wull «»1* tho furnace ut tho;loading elation in indicated at 39 and an entrance ..mout£ 40 to thev furnace is formed through tho end wall 39 rin alignment with Uio upright rollpro 0 and includes an enlargement at tho bottom of the mouth AO and aligned with the stub rollers 13 to permit passage of the carriage 12 on the convoyor into the furnace. Flexible asbestos cloth coaling strips, not shown, ore mounted in the upright edges of the furnace mouth 40.

Side walls 42 and 43 of the furnace 1 carry banks of electrical heaters 44 and 45, Figure 3» which heater banks are illustrated in greater detail in Figures 6 and 8. These heaters face opposite sides of the path of travel of each glass sheet 9 through the furnace and are connectcd together in groups which are individually controlled as will be described.

At the loading station, Figure 2, the carriage 12 i:; locaLcd in position by a retractable carriage atop 47 against which the front cud of the carriage 12 bears so that the carriage is held in sliding engagement with the rollers which are being driven at an initial slow .'••peed and when the stop 47 is retracted movement of tho carriage commences from the loading station into the furnace. A cold flat glass sheet 9 loaded on to the carriage 12 leans against the upright rollers P> at the loading station. The shoot, bein^ cold is not deformable and the necessity for exact alignment of the rollers 0 and 1'3 at Hu- loading station is not as critical as is th;.- - 40255 need for their cxa6t alignment in the furnace and the tilting box. Therefore the rollers 8 which are mounted botweon the beans 35 and 36 at tho loading station are not angularly adjustable but are set in fixed bearing blocks at the angle of tho conveyor, in this embodiment 5° to tho vortical." The lower ends of the upright rollers 8 at the loading station are formed with stub shafts 48 which extend downwardly between the girders 36 and through apertures in a plate 50 which is bolted to the bottom of girders 36. Beneath the plate 50 there are carried self-aligning bearing blocks 51* one for each of the rollers 8. The bearing blocks 51 have lugs which are bolted to the plate 50 and the stub shafts 48 extend downwardly into and through the bearing blocks 51.

At their upper end3 the upright rollers 8 at the loading station are formed as integral elongated stub shafts 53 which extend upwardly between the beams 35 and are each housed in a self-aligning bearing block 54. The bearing blocks 54 are bolted by lug3 to a support plate 55 which is fixed on top of the girders 35. Each of the shafts 53» except that of the roller 8 nearest to the entrance to the furnace* extends upwardly through its bearing block 54 and carries a sprocket wheel block comprising two sprocket wheels 56 and 57. The sprocket wheels for adjacent rollers are connected together by means of drive chains 59.

The elongated stub shaft 53 of the roller 8 nearest to the inlet end wall 39 of the furnace is longer than the stub shaft 53 of the other rollers of the loading station, 40255 mid carrics a single sprocket wheel 56 °"d on its upper .end n main drivo sprocket 60 whio.h is connccted by a r; drive chain 61 to a sprocket 62 on tho upper end of the ■ ' • >- f" '■ •' • - ■: ■ ■ first of the upri$it rollers 8 within the furnace. Tho 5 rollers 8 at the loading station are thus driven from the : some drive'as the rollers 8 constituting the rest of the convoyor. in the furnace. / Within the fUmace it is important to ensure accurate alignment of the surfaces of the rollers 8 10 relative to cach other so that the surfaces of the rollers which provide transient support for the glass sheet all lie in the same plane which is inclined to the vertical at the preset angle, for example 5°. In order to effect this, and as described in the above mentioned co-15 pending Application No. 39806, the rollers 8 within the furnace are mounted in alternating groups of four and throe rollers each, with the rollers spaced about 20 era. apart, ond tho exact location of the lower bearings of each group of adjacent rollers is adjustable horizontally PO at right angles to the direction of the conveyor. The upper ends of tho rollers of each group are mounted in a gear box whoso position is also adjustable horizontally at right angles to the direction of advance of shoots of gloss along tho conveyor. The adjustment of the disposition of the boaring blocks and the gear boxes relative to each other penults alignment of all the upright rollers 8 in the furnace at the required angle to the vertical.

The lower end of each roller 8 in the furnace is foiniiKi as a stub shait 63, which is supported in a self-al'.inning benrinp block 64 which is fixed in a plate 65 - 27 - 40283 which is carricd by dovo-tail slides which slide in slide beds .67 which nro fixed beneath parallel girders 63 which • ..-'v. • - v . -run longitudinally beneath the furnace floor and aro : supported on the specially shaped cross girders 6 which 5 support the. furnace floor. This arrangement is shown in Figure; 3.

Each of the dove-tail slide blocks 66 has an end lug 72 which is drilled and threaded to receive the threaded end of an adjusting shaft 74 whoso other end 10 extends through an aperturcd locating block which is boltc?d to a cross girder 76 extending between the lower ends of the upright girders 4 along one side of the furnace. The outer end of the shaft is threaded and is fitted with lock nuts on either side of the loading 15 block. Each of the plates 65 carrying the bearing blocks 64 for a group of rollers has two V-slides and i > the adjustment of the two shafts 74 permits adjustment of the disposition of the lower ends of that group of rollers. 20 The upper ends of the group of rollers 8 are of reduced diameter Jind the elongated stub shafts 78, Figure 5, extend into a gear box 79 mounted by anti-vibration mountings on dove-tail slides which are located in slide beds 82 which are mounted on top of the longitu-25 dinally extending girders 7. In the same way as the slides for the Dower bearings of the rollers, each of tho dove-tail slides 81 has an end lug 83 which is drilled and threaded to receive the threaded end of an adjustment shaft 85. The other cud of the shaft 85 extends "through 30 an aperturcd locating plate 86 which is mounted on a girder - 28 - 40255 67 which rum? longitudinally of tho furnace beneath ; ' . " : •- ■ :'3't iSj: tin? orosn cii-derc/?. The ouler ond of theVshaft 85 S V •• :• ; .'.A - -v . §' ■££■ !«•.I.KtvnilftP'aiul ii\. fltlctl with lock nul.rv ttfl on rLUu-r ^ "> • ■ ■ " ■ . f- .-'f; r.lili'iof llu* locaUii:', pl)iL<* M(». J. •' :&.• : '• y: f ' '*,f 5 ;W jEacl) of the guar boxer. 79 is seated on two such •'? •/'. • «V*' • - # ■ *'r- ? . . slides and rotation of the shafts 85 of the gear box moves the dove-tail slidbs 81 in their slide, beds 82 so that the position of the gear boxes 79 can be adjusted, as required relative to the adjustment of the bearing 10 blocks 64 for the lower ends of the rollers to ensure that the rollers 8 driven by that gear box are at the required predetermined angle to tho vortical.

The position of the gear box 79 for each group of rollers is adjustable in conjunction with adjustment of 15 the plate 65 carrying the bearing blocks for the lower ends of the rollers so that in setting up the furnace all the rollers 8 of the conveyor extending through the furnace can be accurately aligned so that the glass supporting surface of each of the rollers 8 is at the same angle to 20 the vertical, for example 5°.

The bottom stub rollers 13 define a track for the movable carriage 12 which carries the glass sheet 9 through tho furnace and these bottom club rollers project through spaces between the upright rollers 8 along the whole length * ?5 of the conveyor arid are mounted at an acute angle, in this embodiment 50°, to the upright rollers 8.

The five bottom stub rollers 13 which support the carriage 1? a I the loading :;tat.ion are shorter than those thai pro.ji ct inwardly into the furnace, and are located in ■'0 at 11 - r 11: < 11 * . j'ac«\. h'lween I'n- upright rollers H. _ 29 _ 40355 CLASS fMUVORT CAKRTACK Tho carriage 12 which constitutes the movable support /or a shock of clous 9 is illustrated in more detail in Figures 4 and 5. The carriage is made of .'shout otrr'l. liuril. to an ungl<\ uo us to provide* two Tuccs which mutch the acute ancle between the upright rollers 8 and the stub rollers 13. Tho upright ft> 148 of tho carriage is the longer face and carries two support plates 149» the upper edge of each of which Is widened to provide a support shoulder 150 whose upper surface 151 is provided with a non-slip refractory coating. The rear edge of the upper surface 151 of each shoulder 150 is formed with an upstanding land 152 of width which predetermines the minimum offset distance of. the lower edge 153 of the glass sheet 9 from the supporting surface of the upright rollers 8 when the carriage is in position for conveying the sheet through the furnace with the face 148 of the carriage bearing against the supporting surfaces of the rollers 8 and with the lower shorter face 154 of the carriage supported on the bottom stub rollers 13. Figure 5 illustrates how the upper edge 155 of the glass sheets rests against the rollers 8 when the i glass is loaded at the loading station and Figure 4 uhows how tho support shoulders ore adapted to the particular shape of the sheet of glass to be bent. The shape of the glass sheet matches the styling of the vehicle in which the sheet is to be embodied.

By reason of common drive to the rollers 8 and 13 from a hydraulic motor, and by choice of suitable gearing with similar fractional engagement of -30 - tho faces 14''. and 154 of the carriage with the upright rollers.;.pnd _t;n; stub rollorsi Tj> respectively, tho movable carribgo is always advjincing with tho some linear' speed aa. the surface linear ..speed of the up-^richt^rollers 8 against which the sheet of glass rests£and which; provide -transient support for the upper; edge of the glass sheet. v The carriage also carries a stop member 156 at its front end for abutment against the retractable carriage stop 47 at the loading station as shown in Figure 2 and for eventual abutment against a second carriage $top in the tilting box 17 when the glass sheet is correctly located between the bending dies. Also mounted on the carriage is striker 157 near the front end of the carriage for engaging a lim'4; switch SI mounted just outside the furnace at the loading station. A further striker 158 is mounted on the carriage at about midway location to engage an actuating member in the furnace for a further limit switch, not shown, which forms a part of a control system for regulation of the speed of travel of the carriage through the furnace when the whole of tho glass sheet is within the furnace.

FURNACE HEATERS Figure 6 illustrates the way in which the electric heaters indicated at 44 in Figure 3 are mounted on the furnace side wall 42 facing the back of the upright rollers 8. Each of the heaters is an electric resistance wire heater 159 the wire being wound on a ceramic red which is carried by two connection rods 160 which extend through the side wall 42 of the furnace. Current « v«i»a fHippUed 'through the:to connection rods 160. Tho heatero ] !;9 are iirran/rcd in a chcvron pattern and the heaters are connccted together in series in jroupu which groups m o de-1.tailed by the chain lines in Figure 6. For example tho upper group of hoater3 first encountered by the glass which is advanced into the furnace in the direction' of the arrow 161, is indicated at 162 and comprises ten heaters 159 which are connected together in series as illustrated In Figure 7. One end 163 of the series connection of the heaters connected to one I line 164 of a power supply. The other supply line 165 of the power supply is connectcd to a thyristor control circuit 166 of conventional design which controls the flow of current through the scries connected group of lioaters 159 in response to firing pulses supplied to the trigger electrodes of the thyristors on lines indicated by the firing pulse line 167 which is connectcd to a firing pulse generating circuiI 168 which is also supplied with power from the lines 16A and 165• A control thermocouple 169 is mounted in the furnace within the limits of the group of heaters 162. This thermocouple is connected into a temperature control circuit 170 of conventional design and controls a simple on/off switch indicated by the two way switch 171 to switch into the blocking oscillator of the firing pulse gftnerator circuit 168 , control by one or other of Wo potentiometers 172 nnd 173• The sotting of the potentiometers 1.72 and 173 are r.ueh as to /:ive, in known.manner, respectively high and low levels of power dissipation in the proup of heaters - 32- 40255 102 30 ,thutin response to . Hie temperature in tliat part-of. tho furnaco within the limits of tho group or heaters 162 as sensed by the thermocouple 169, the / • V . •; •' . ' J. ' ■ . . ' .!•• , •; . ' . '» . * ; level of. power dissipation can be switched .between ... thc high and low levels in order to maintain the * >,'$£> ;>.r\ ..... • ;• ' • sensed temperature at a desired valueset bya set point adjustment provided in known ; manner by adjustment of. a. potentiometer in the control circuit .170.; Eight series connected heaters are arranged in chcvron fashion in a second group 174 at the inlet end of the furnace lying below the group 162. Thereafter the heaters are arranged in two sets of three groups* each group consisting of nine heaters connected together in the series and each having an associated control thermocouple 169 and being supplied through a thyristor control circuit under the control of the appropriate thermocouple 169 and temperature control circuit as illustrated in Figure 7.

Operation of each group of heaters can be set individually by the set point adjustment in the associated temperature control circuit. For example for heating a sheet of glass 2 mm thick to a bending temperature of 590°C, which is attained substantially uniformly throughout the whole of the glass sheet, the set points of the temperature control circuits may be such that the temperature at. the thermocouple 169 within the group of heaters 162 is 700°C, and the temperature at the thermocouple 169 within the group 174 is 750°C. Of the subsequent jjroups of heaters the temperatures at the thermocouples 169 are 700°C for the upper groups, 725°C 40283 ...» * « » for tho middle groups, and 7'jO°C for the lowor croups* ♦ Figure- 0. illustrates thcelectricol heaters 45 J; ■ \ .*.*■ ••'..A* ^ - «. • which aro/ mpunted oh the side wall- 43 .of the furnace ' :^aoingitKo^loss Sheet "icaxilnc e^ainstt the rollers8. ■/■"■:■■■ **. • '••*-. • ,t; .. U> / ; fklnithii^drniwihgV the direction of glass7 movement 161s Hf. ?'<$■■ v • '• ■■ V"-- J: •* ^ sisshownfron-thel'eft handsend of the Figure'. ; 'The > : Y': > •' • V ' ■ ■ •• . ' : • - < .• i heaters ^159 are wire-wound heaters on ceramic tubes of * • • *?* *. v • •' •. . ■* t •' the- oaoie kind as illustrated in Figure'; 6 and are mounted '.on connection rods 1C0 which extend through the side ' wall .43, of the furnace. The heaters are divided up * • Figure 5 illustrates how the upper edge 155 of the gloss sheet rest:; against tho near-vertical support rollers H when the cold shoeI 0 1s loaded on to the !'• support carriage 1? at the loading station and during the initial part of the heating of the glass. As the glass is heated during its travel through the furnace and the glass approaches the temperature in the range 580°C to 660°C to which it is to be heated, the glass 20 becomes sufficiently softened to relax against the support rollers 8, and could become unacceptably deformed if it were maintained at that temperature for too long.

Initially the upper part of the sheet relaxes against the rollers 8 and the length of effective supporting surface of the rollers 8 which extends downwardly below the top edge of Uirglass sheet must- always be sufficient to accommodate pf-rmis'3iblc relaxation.

A timer in tho control circuit for tlio roller drive ir. set :;o that, tin; glass has reached its desired temperature - 35 - 40285 which, in one manner of operation, is substantially uniform over the whole sheet and through its thickness by the time the hot sheet is accelerated out of the furnace into the tilting box, before the amount of s doformation of the sheet by initial relaxation of the upper part of the sheet against the rollers 8, followed, if acceptablc, by outward bulging of the lower part of the sheet, exceeds the limits of acceptable deformation of the sheet.

° Settings of furnace temperature may be employed as set out in Table I.

TABLE I Heater Sections Temperature (°c) Mean Furnace Temperature (°c) 680 705 730 710 700 725 750 730 720 745 770 750 780 805 830 810 At any particular mean furnace temperature the time taken for a sheet to reach a required final temperature is dependent on its thickness, and examples of operation for 15 a range of class thicknesses from 2.2 mm to 15 mm and of heating times required to achieve a-'final glass temperature j.n the ran&c 580°C to 700°C, are described in detail in the rbovo mentioned Specification. - 36- 40285 MfliNACK KXTT SEAL A flexible ooal indicated at 246 in Figure 9 io provided botwocn the exit end 247 of the furnace and the iniet end wall 248 of the tilting box 17. The form of the seal- is shown in detail in Figure . 10 and comprises a flange member 249 fixed to the xUrnacc wall 247 and a similar flange member 250 fixed to the tilting box end wall 248 and extending outwardly and overlapping the flange member 249.

When the rocking frame is horizontal the flanges are parallel and a sealing member 251 is trapped between the flanges. This sealing member 251 comprises a knitted stainless steel mesh stocking filled with bulked thermally insulated ceramic fibre. - 37 40255 A blanket .'*■>.** woven from nrrtimlc I'lbn* InclndliiK nr» in lop-woven :: In in!l con stool mesh in secured between Ihe flange members 250 and 249* and the walls to which they are fixed. The Blanket has sufficient flexibility to accommodate the tilting movement of the wall 248 relative.to the wall 247 and.preserves the seal when the'tilting box is in its tilted postion.

TILTING BOX The tilting box 17 which is illustrated in Figures 9, 11A and 11B defines a chamber in which the bending dies are' enclosed, and comprises the inlet end wall 248 an exit end wall 253» a roof 254 formed with a step 255 leading down to the top of the inlet end wall 248 and a step 256 leading down to the top of the outlet end wall 253. The depth of each of the steps is adjustable to accommodate adjustments of the hoist mechanism for different heights of gluss sheets as will be described with reference t.o Figures 30 and 31.

The tilting box further comprises a rear wall 257 and a front wall 258 and floor parts 259 and 260 extending rearwardly from the bottom of the front wall 258, and extending foi-wardly from the bottom of the rear wall There is n vertical elongated entrance to the chamber formed in the inlet end wall 240 and an exit * 262 formed in the outlet end wall 253 through which exit the carriage 12 is discharged after the glass sheet being bent has been lifted off the carriage and is being bent between the bending dies. The exit 262 lendr. to the extension I' of the conveyor shown at the left hand sido of Figure 1. 40285 The roof 1*54 iu :;uapendi.-d by huxigcru 264 from u support at:-..oturo including a cross beam 265 extending bctwoon vertionl pillars 266.

The pnrtu 259 and 260 of the floor are supported 5 on floor support girders 267 and 268, and define between •v. ..'>*• * . them-'a mouth 269 in tho floor of the furnace through vuich.a bent glass sheet?can be lowered* The walls, roof and floor parts of the tilting box are fabricated with an outer steel shell lined with refractory 10 material.

The chamber defined within the tilting box 17 is heated to the temperature of the glass which enters the tilting box from the furnace so that the bending dies which are enclosed within the tilting box are at 15 the temperature of their environment and are therefore at about the same temperature as that of the glass sheet when it enters the tilting box. The temperature within the tilting box is maintained by gas burners indicated at 270 which are connected by ducts to inlet 20 slots 271 formed in the front and rear walls 257 and 2!?8 of the tilting box. There are four gas burners 270 feeding four slots 271, two in each of the front and back walls and each of the burners is controlled by a thermocouple fixed in the male die as neax* to itu 25 bonding surface U3 posuiblu, to ensure the maintcnanco of a uniform bonding temperature, in the range 500°C to 650°C for example 610°C, within tho tilting box. Tho burner:; 270 are connectcd by flexible ducts to gas ana combustion air supplier., including means controlled 50 by the thermocouple in the male die to vary the air:gas x'atio fed to the b*ix*ners. -39 - 40355 The gas burners maintain a positive pressure of hot gnsca in the tilting box and hot gases flow downwardly throwGli- '..he exit mouth beneath the box and meet uprising gases. A pressure balance usually exists jus I. below the boost hen tern 27.

The massive, rocking frame, on which the tilting box is mounted, which frame is indicated at 20 in Figure 1, comprises side girders 272 and end girders 273 welded to the end of the side girders 272. Each of the side girders 272 Is seated on and welded to a pivot block 274 which carries trunnions 275 which are mounted in bearing blocks 276 which are seated on a base support plnte 277 which provides the upper surface of a ledge 270 which is cut into the side walls of the pit. The rocking frame is balanced on the trunnions 275 as is the whole of the tilting box construction and its associated equipment carried by the rocking frame so that-the fran.e 272, 273 can be readily tilted from horizontal to the tilted position at about 5° to the horizontal which is illustrated in Figures 11A and 11B.

Cross girders 279 and 280 extend across and above the rocking frame between the side girders 272 being mounted on the side girders by end brackets 281.

A cross girder 282 is seated directly on the side girders 272 of. the rocking frame and the floor support girders 267 are seated on the cross girder 282. % At the left-hand end of the rocking frame as viewed in Figure 11A, a plate 283 is supported by spacer blocks 284 on the end girder 273. The plate 283 is a short plate centrally mounted on the end girder 273. - 4o - mul .-iUffcnlnf; girdera 2i'Sj extend from the plate 203 to the cross beau 279.

( Mounted fir.ove tho plate 203 and the cross beam 279 Qto,n pair of parallel support boams 266 which are *V. - » respectively mounted by support blocks 207 "and 288 on thefplate 203 and the cross beam 279. The parallel support beams 286 support an actuator unit 289 for the male' die 16 which is mounted on a die mounting assembly 291.

Similarly at the right-hand end of the rocking frame a central plate 292 is mounted by support blocks 293 on the upper face of the end girder 273- The plate 292 is fixed by stiffening beams 294 which extend hetwocn the plate 292 and the cross beam 280, and a pair of parallel support beams 296 for an actuator unit 29"/ for the female die 15 are carried on the cross beam 280 and the plate 292 by support blocks 298 and 299.

The female die 15 is mounted on a die mounting assembly 300, which is carried on the die actuating unit 297.

The rocking frame 272 , 273 is rocked by means of a single hydraulic cylinder 301, Figures 11A and 12 which is mounted by means of trunnions 302 between brackets 303 which are fixed to a beam 304 extending across one end face of the pit. The cylinder 301.Uas a ram 305 which extends upwardly and has a head 306 which carries trunnions 307 which pivot in bearings in bearing support brackets 309 which are fixed beneath the r.t-ntre of the end girder 273. 40255 The horizontal position of tho rocking frame and the onclo of tilt of the framo is sottable by stop means illustrated in Figure 12. Near either end of tho end girder 273 to which the ram 305 is attached there v. are U-shaped stirrups 310 extending below the beam.

Bach stirrup 310 is welded to the beam and strengthened by brackets. Within each stirrup and mounted on the beam 304 fixed to the end wall of the pit there is a 8top block 311 of rectangular cross-section, and a second stop block 311 is mounted on the beam 304 below the stirrup. Adjustable stop bolts 312 and 313 are secured to the base of the stirrup and respectively extend upwardly and downwardly from the base to engage the blocks 311* The head of the bolt 312 abuts against the upper block 311 when the frame is rocked to its tilted position and the head of the bolt 313 abuts against the lower block 311 when the rocking frame is tilted back to its horizontal position. Adjustment of both the stop bolts 313 ensures that the rocking frame is returned to a horizontal position and adjustment of the bolts 312 provides an adjustment of the setting of the angle of tilt of the rocking frame bringing the upright rollers 8 in the tilting box 17 into exact alignment with the upright rollers in the furnace to receive a hot sheet of glass for bending.

At~either end of the other end girder 273 of the rocking frame there is an hydraulic shock absorber 314 having a ram which bears against the shelf 278 which oxtendn along tho sides of the pit. Those shock absorbers atoady the rocking frame as it nears the end of it3 tilting movement. 40355 f Also carried on the ror.Uing frume there Is a .support structure indicated at 315, for supporting the gas burners 270.

, An'indication of the disposition of the rocking - \ •*/ . • frame and the' tilting box is given by switches S7 and '_S8 which are mounted alongside one of the stirrups 310 and.jare operated by a striker 316 on that stirrup. ' T^e switch S7 is closed when the frame is in its tilted position and the switch S8 is closed when the .frame is! horizontal. Both switches S7 and S3 are connected into an electrical control circuit for the apparatus as will be described.

The rollers 8, 13 and 18 in the tilting box 17 are driven by the same drive as the furnace rollers. The upright rollers 8 and 18 are driven from their upper ends by gear boxes 317, Figures 9 and 11, of similar construction to the gear boxes 79 which drive the upright rollers 8 in the furnace. The gear boxes 317 are mounted above cross-girders 318 which are fixed between the cross-members 265, being adjustably mounted on the cross-girders 318 by means of V-alides in the same way as the mounting of the gear boxes 79 of-the furnace by means of the slides 01, 82 as illustrated in Figure 3« The drive to the gear boxes 317 is by a shaft 319 coupled by a flexible coupling 320 to an intermediate shaft 321 which is coupled by a further flexible coupling 322 to an output shnft 323 of a right angle drive unit 32'« which is mounted on one of the upright girders 266. The drive to the right angled drive unit 40255 2*'4 through a flexible coupling 325 ia by a tronomis-.."ion shaft 326 which io held in bearings 327 on the . upright giruur266 and tho lower end of which is coupled by a flexible coupling 328 to a further right angled 5 drive uolt 329 which is mounted, on the cross girder 280. .- : ' •' - The lower end of each of the upright rollers 8 and 18 in tho tilting box is formed as a stub shaft 330 which is supported in a self-aligning bearing block 331 10 fixed to a plute 332 which is mounted by brackets, one of which iu shown at 333 on the ends of girders 334 which canti lever out from the centre web of the cross-girder 280. The plate 332 is adjustable laterally with respect to the brackets 333. The free end of each 15 of the cantilever girders 334 is supported by a prop girder, not shown, which extends upwardly from a cross-girder, omitted from the drawing for clarity, spanning the two side girders 272 of the rocking framo. Supports for the floor support girders 268 beneath tho floor 20 part 260 of the tilting box are also provided from that cross-girder.

A box girder 336 extending transversely of the girders 334 is mounted on the upper faces of the girders 334. The box girder 336 provides a mounting 25 oupport for the bottom stub rollers 13 and their drive means.

Both the antjlc of inclination of the stub rollers 14 relative to the upright rollers 8 nnd 18 and the extent or irojection of the rollero 13 between the 30 rollero a and 1U is adjustable in the same maimer as - 44" 40255 for Hit In>1.1.uiii ::lu|> rollir:. I '• ill Mm* I'urnnrr. Tho ilrivt* l.o llu* I>.>U.i.111 ntuh inllrra J'5 In l»y meann of n shaft 330 which extends parallel to the box girder 336 nnd is mounted in bearings carried by brackets fixed to the girder 336. The drive from the shaft 338 to the bottom stub rollers 13 is through right angle drive units 339 which are qIso mounted by brackets .on the box girder 336. Each right angle drive unit 339 drives the corresponding stub roller S3 through an intermediate shaft 340, which through a further flexible coupling 341 drives a right angled drive unit 342 which drives a shaft 343 on which the ferrule of the roller 13 is mounted. The shaft 343 extends through a cylindrical bearing assembly 344 whose body has integral sleeves 345 which are bolted to an adjustable mounting.

The shaft 338 is driven from the bottom gear box 119 which drives the bottom stub rollers 13 at the exit end of the furnace adjacent the tilting die box 17. A conventional articulated coupling, not shown, couplcs an output drive shaft from the bottom gear box 119 with the end of the shaft 338 adjacent the exit ond of the fumaco. The other end of the shaft 338 is connectcd through a right angle drive unit and a flexible coupling to tho input shaft of the drive unit 329 thus providing the drivo to the rollers 18 through the goar boxes 317.

Figure 13 illustrates in more detail the mounting of tho bottom stub rollers 13. The cylindrical bearing nssemMy 344 is bolted to the lower face of an inclined support, plate by means of bolts which extend - 45- <10255 through nleoves 345 integral with the body of tho bearing assembly 344. A pivot 347 extends between trunnions 340 on the plato 346 and aloo mounted on the pivot 347 between the trunnions 348 is an enlarged head 349 of a horizontally disposed top plate 350 which is joined by webs 351 to a face plate 352. A set screw 353 is threaded through a hole in the-lower inclined plate 352 and the end of the bolt 353 bears in a boss 354 formed on the lower end of the support plate 346. Adjustment of the bolt 353 adjusts tho angle of inclination of the stub roller 13 and when the required angle of inclination is achieved locknuts 355 secure the bolt in that position.

A slide plate 356 is bolted to the lower face of the box girder 336 and a plate 357 for supporting the buse unit carrying the bearing 344 is mounted beneath the slide plate 356 by two claaping members 358 which have flanges 359 fitting over the edges of the slide plate 356 and attached to the plate 357 by means of bolts 360. An intermediate spacer plate 361 is welded beneath the plate member 357. She main plate 350 of the base unit is attached to the spacer plate 361 by means of bolts 362 which extend through longitudinal slots, indicated at 363, which are formed in the top plate 350. The bolts 362 are screwed into tho spacer plato 361. Dowols 364 extend from the lower face of the plate 361 into a longitudinal groove 365 formed in the upper face oT the top plate 350. An adjuster screw 3i.ii ia th 1 doil into a raounLin,; block 3b7 which is bolted lu-uoa'.h the roar end of the ur>por plate member 40885 3V.'. The Inner end of the adjuster ncrow couples willi n plnlo which in luil led near 1.1 to rear of the 1-oji plntc> J5f>C>.

. In ^ortlor to adjust the'extent of projection of the ;> - bottom-stub, "roller 33 between the upright rollers 8 and ..... 10,;. the bolts 362 attaching the upper plate 350 to the i • • ' **- * . ' \ spacer.plate 361 arc loosened and th?position of the whole base unit is adjusted by rotation of the adjuster screw 366. When the stub roller 13 is correctly posi-10 tioned the base unit is clamped to the spacer plate by tightening the locking bolts 362. The stub rollers 13 in the tilting box must be corrcctly aligned to fora a straight track for the carriage 12 which is an extension of the track defined in part by the stub rollers Tj 13 in the furnace, by adjustment of both the angle of Inclination of the stub rollers 13 in the tilting box and the extent of projection of those rollers. When the required position is reached the stub rollers are clamped in position. 20 Tho upright rollers 8 and 18 in the tilting box 17 are also adjusted and clamped in position by the adjustment of the location of the gear boxes 317 and of the plate 332 which supports the lower ends of the rollers 8 and 10, so that the upright rollers 8 in the ;>•> tilting box 17, when tilted, also form an aligned extension of t.he conveyor surface defined by the surfaces of the rollers in tho furnace.

FKMAI.E DTK ACTUATOR UKIT Tho female die actuator unit 297 and the parallel •o support 1'i-ar.is 2°e for thai unit are shown in more detail in Figures ]'i to 17. _ 47 _ 40285 ; * • . . • ^ ' The two parallel boa:n:j 296 nro tied togethor by . four^crons-'^irdoro 380, tho endo of which oro welded to Jtho-befu/isj 2'J6. The crouit-girders 380 carry a tonne plate 381 which extends parallel to and midway between v 5 , - the girders 296. a guide track 382. of massivo U- section is seatod on top of the base plate 381 and a central guide channel 303 formed in the guide track 382 serves to guido rollers on the die aotuating assembly 286 as will be described. 10 The location of the base plate 381 and the guide track 382 on the cross-girders 380 is adjustable and when correctly positioned the guide track 382 is clamped to the cross-girders 380 by means of clamps each comprising a clamping plate 384 on one end of a pillur 385 15 the lower end of which screws into the upper face of the appropriate crocs-jirder 380. Each clamping plnte 384 is held in position on a threaded rod 386 which is scrcwod into a threaded aporture in the cross-girder 380 and which carries on its upper end a clamping nut 20 387 which when screwed down tightly clamps the plate 384 firmly on to the upper surface of the guide track 382.

For angulnr adjustment of the guide track two parallel luga 3*J8 extend from the rear end of the guide 2b track 3**2 and are fitted with adju.-iter bolts ^89, the inner ends of which engage opposite faco3 of a fixed luo '5\}0 which io bolted to the roar end face of the baac plate between the parallel lugs '368. A circular pivot block 3'Jl ia bolted beneath the guide 30 track 3»»? tcv.:.ni:; its i,'runt end. The pivot block 3P-L _ 48 - 40255 fito in a circular houciug 3'J'? i« the top face of tho baiio plate 3t»l. Angular ailjuutmunt oi' tho guide track 3»i2. iu by •-icijuutmuiit of tlio bolto 3^9. Transvuraely extending blocks '59.3 which oxtend outwardly towards tho 5 main girders 296 are welded to the aide faces of the housing 392. Adjuster bolts 395 threaded through bushes 396 welded to the outside of the beams 296 bear on the outer faces 397 of the blocks 393* Lateral and coarse angular adjustment of the disposition of the 10 guide track 382 is effected by adjusting the bolto 395, and whon the guido track 382 has thus been correctly aligned by fine angular adjustment by the bolts 389, the clamping nuts 387 arc tightened to clamp the guide track and the base plate 381 on to the cross-girders 15 300.

The die actuating unit 297 comprises two parallel box section girders 400 which, are joined near their ends by cross-members 401 which are fixed beneath the girders 400. Each of these cross-members 401 is in 20 the form of an elongated plate the ends 402 of which are inclined upwardly and teruinate in foot plates 403 which ore bolted to brackets 404 on the box girders 400. The upper surface of each of the support girders 296 is fitted with two bed plates 405 which extend "or 25 some distance along the upper surface of botn girdexa 20b in tho Region of both ends of the girders. luau.ing on them.- bod plates 405 arc recirculating ball bearing padu 406 which are fixed to the side of the box girders 40U by biMekcts 407. Tho ball bearing puds 406 supyort 30 tho box ,''.inior.'i 400 and the female die actuating mociin-nism 300 01: tho main girders 296. .. 49 _ 40255 Kach oi' the crottu-ttiCDboru 401 carries a downwardly extending spindle 400' carrying on its lower end a guide roller 409 which runs in tho channel 303 in tho guide track 382 and thcroby guides inward and outward movement of tho die actuator along the support girders 296.

A pluto 410 fixed on the top of the guide track 382 provides a base plate for a stationary hydraulic cylinder assembly 411 which is held in a central collar 412 having stub shafts 413 which pivot in brackets 413 which are bolted to tho base plate 410. Tho cylinder 411 is held In a cage which extends between the cylinder heads and is coupled to the collar 412.

A r-a 414 is connected to a piston which operates within the cylinder 411 and fitted to the outer end of the ram is the ball of a ball and socket joint indicated at 415 which is fixed to an fend plate 416 which extends between and is welded to the outer ends of the box girders 400.

Movement of the ram 414 in either direction transmits drive to the box girders 400 and, guided by the rollers 409 which run in tho guide track groove 383, the box girders 400 run on top of the main support girders 296 in the sane direction as the direction of movement of the piston in the cylinder to move the female die 15 into bending position and to retract tho die from that position.

A bracket 417 is bolted to the rear end of the t.uiile track nbove the lu^rr. 3158 and carries two ir.toji boll.-. 418 and 41"). The extent of backward movement 40255 of th« die aciunl.or during opening of the dies is limited by abutment of tho end plute 416 against the stop bolt 418.

Tlie stop bolt 419 is a longer bolt and extends through a slot 420 in tho plate 416. The inner end of tl*> bolt 419 is fitted with an enlarged head 421 against''which' tho inner surface of the plate 416 abuts when the die 15 is at the limit of its forward movement and is closed against a glass sheet which is thereby bent against the surface of the male die.

Mounted on a plate 422 fixed to the side of one of the support beams 296 are four limit switches S9, S10, Sll and S12. The switches are staggered at right angles to the plate 422 so as to be operated as appropriate by strikers 423 which are fixed beneath a plate 424 which is cantilevered out from the side of one of the bcx girders 400.

These switches and their strikers are located so as to give the following indications:- S9 - female die partly out 510 - female die in 511 - female die partly in 512 - female die out FEMALE DIE AMD SUPPORT The construction and mounting of the female die 15 is shown in more detail in Figures 18 and 19.

Tho female die 15 is of open frame construction made up in sections which can be moved between the upright rollers 18 within the tilting box as indicated in Figure 9. I'hcre are two end r.octions 425 shaped to 40255 match tho ond configuration of tiiu ulncu »hoet when » bent, two outox* top sections 426 und three Inner top auctions 427 which pass between tho shafts of the rollers 1U. The open frame construction is completed by three lower sections 42U which also pass between the rollers 111. Bach of these ring frame sections is constructed in conventional manner of heat-resistant steel with a refractory facing which contacts the margins of the hot glass sheet.

All the frame sections 425, 426, 427 and 428 are mounted on a base frame whose shape matches that of the ring frame die. The base frame is a steel struc-ture comprising upper and lower members 429 and 430 and end members 431. These members are of L-section and stout construction and are welded together.

Each of the frame sections 425, 426, 427 and 420 is attached to the b^e frame by adjuster assemblies, each of which comprises an internally threaded sleeve 432 which is fitted with a threaded rod 433 and is attached to the outer surface of the appropriate member of the base frame by an L-shaped bracket 434 which is welded to the outer surface of the base frame, the sleeve 432 being welded to that bracket. Hutu 435 are threaded on to the rod 433 at either end of the sleeve 432. One end of the threaded rod fits into a slot in a block 436 which is welded to the back of the appropriate female die frame section; the end of the rod 433 being held in the clotted block 436 by a rivot pin 437. 40258 Each of the sectiono of the female die frame is mounted in this way there being three such assemblies of sleeves 432 and rods 433 mounting each of the small sections 426, nine such assemblies mounting 5 each of the end sections 425, four such assemblies mounting each of the longer sections 427 and 428, and -. three assemblies mounting each of the shorter central sections 427 and 428.

The locknuts 435 on the threaded*rods 433 are 10 adjusted until all the sections of the die frame construction are correctly set tip, and when this correct position has been achieved it is fixed by welding the blocks 436 to the ends of the threaded rods 433. 15 The steel base frame 429, 430, 431 is welded to and carried by a support structure comprising two vertical struts 438 which are welded between the upper and lower members Hk9 and 430 of the base frame, and cross struts 439, 440 and 441. The base frame Is 20 attached to the die support 300 by an adjustable mounting which will now be described with reference to Figure 20, which is a vertical section through the female die support unit 300 and comprises a structure 445 of generally rectangular cross-section comprising 2r. two parallel box-section beams, which structure is closod at its tnd adjacent the die actuating unit by a plate 446 whlSh is welded to the ends of the box-section beams. _ 53 - 40265 At tho end of the die support adjacent the i baso frame for the die a locating plate 447 is fixed and a vertical slot 448 in tha plate 447 receives the free end of a locating pin 444, which is fixed to the centre of - the cross strut 440 of the base frame.

The base frame for the female die is suspended from the die support unit by an adjustable mounting by which angular adjustment of the female die about a horizontal axis parallel to the plane of the base frame is possible. Lugs 450 are welded at right angles to the upper frame member 429 and the cross strut 439. There are two such pairs of lugs 450 as illustrated in Figure 19» and between each pair there is mounted a locating bar 451 which bars 451 engage in a clamping hook arrangement on the die support unit.

Each of the locating bars 451 is seated in recesses in lugs 452 which are fixed in pairs to the end of the die support unit as shown in detail in Figure 21. The base frame and the die thereby hangs from the lugs 452. A shaft 453 extends through the die support unit and carries a clamping hook 454 which fits between the lugs 45 and engages behind the locating bar 451. A reduced diameter threaded end 456 of the shaft 453 projects through the rear end plate 446 of the die support unit, and a stack of spring washers 457 Js fitted on to the end of the shaft 453 between the rear face of the plate 446 and a face of a clamping nut 458 which is threaded on to tho end 456 of the shaft. 54- 40255 When tho clamping nuts 450 of both shafts 455 ore screwed tight the locating bars 451 are firmly damped between the clumping hooks 454 nnd tho ltw;n Tho oJninpiitg proutmru nppliud doptnidu on tlio utll'fnous. of tho spring wauhors 457 which are hold in compression by the clamping nuts 458.

A locating bar 460 is mounted centrally on the lower cross strut 441 of the base frame by means of lugs 461 which are welded to the cross strut 441. The locating bar 460 Is engaged by a clamp assembly which is mounted on the outer end of a tubular shaft 462 which also extends through the die support unit. The clamp assembly comprises a jaw member 463 carrying an upstanding end lug 464> A mounting plate 465 is welded to the jaw member 463 and the end of the tubular shaft 462 is welded in a hole in the mounting plate 465. A clamping shaft 466 extends through the tubular shaft 462 and has a threaded end which screws through a threaded hole 467 in a plate 460 which is fixed to the mounting plate 465. Adjacent the clamp assembly the tubular shaft 462 passes through a bearing sleeve 469 which is housed in a support plate 470 which extends transversely between tho centre plates of the die oupport unit. The end of tho clamping shaft 466 can be extended towards the end lug 464 of the clamping jaw so that the central locating bar 460 on the base frame iu clnaped up against the end lug 464 by tho end of the c] .-unping shaft 466. 40255 The other end of tho tubular ahaft 462 extonds through a boaring aloeve 471 In the rear ond plate 466 of tho dlo support unit. A U-shapod braoket 472 having parallel flangoo 473 and 474 ia attached to \ the rear end plate 446 by bolts 475. Both the 5 flanges 473 and 474 of the bracket are drilled for the passage therethrough of the tubular shaft 462.

She outer end of the tubular shaft 462 is threaded and is fitted with lock nuts 476, one on either side of the flange 474 of the bracket. 10 She outer end of the clamping shaft 466 extends beyond the end of the tubular shaft 462 and is squared off as indicated at 477 for engagement by a tool for.rotating the clamping shaft 466 to clamp the locating bar 460 against the end flange 464. 15 By means of this adjustable mounting the angle of tilt of the female die to the vertical can be adjusted by slackening the lock nuts 476 and adjusting the oxtension of the tubular shaft 462 to alter the position of the end flange 464. The adjustment is 20 carried out with the upper clamping shafts 453 and 466 loosened so that the female die can pivot and when tho desired angle of tilt has been achieved the lock nuts 476 are tightened to clamp the tubular shaft 462 in position and the clamping shafts 453 are tightonod 25 to clump the jaw member's 454 against tho locating bars 431 and tc clamp the locating bar 460 against tho end flange 464.

The die oupport unit can also be angularly adjusted about a central axis generally perpendicular 30 to the die surfaces. - 56 ~ 40255 A circular boss 480, FJf^ire 20, io provided on tho face of a iVont end plate 481 of the die actuator unit. Tho boss 400 closely encages in a circular recess 482 formed in the abutting face of the rear 5 end plate 446 of tho die support unit which is attached by bolts 483» Figure 22, to the front end plate which is welded to and spans the front ends of the two box girders 400 of the die actuator. The bolts 483 extend through vertical slots 484 formed in DO the plate 446 and through horizontal slots* not shown, in the plate 481 which horizontal slots are at right angles to the slots 484.

At the centre of each side edge cf the plate 446 there is fixed a lug 486 which extends outwardly from 15 a plate 487 which is bolted to the plate 446. Two pairs of lugs 488 arfe welded to the opposing face of the plate 481 and each lug 486 lies between a pair of lugs 488. Each of the lugs 488 carries an adjusting bolt 489 which bears against the lug 486. By adjust-20 ment of the bolts 489 at both sides of the assembly, the die fixing box and the dies are rotated about' a central pivot formed by the circular boss 480 in its recess 482. When the female die has been brought to the required angular alignment about that axis the 25 bolts 483 are tightened to lock the die fixing box» and the die in that position.

MALE DIE AND MALE DTP ACTUATOR UNIT The male die 16 is mounted on a male die support unit ?.91, itself mounted on nn actuator unit 209 of oO similar construction to tho support unit and actuator - 57 - 408BS unit for tho female dio Just described with reference to Figures 14 to 17 and 20 to 22% The relative disposition of tho male and feaale dies la shown in moro detail in Figure 23 which is a view of the dies 5 looking from the outlet end of the tilting box with the male die 16 at the right-hand side of the figure.

Tho male convex die construction is shown in more detail in Figure 24 and comprises a continuous die face 490 of sheet steol which is perforated as indicated at io 491 and i3 provided with a coating of refractory material for engaging one face of the hot glass sheet which is bent against that surface by the open frame of the female die construction. A shaped frame 492 provides a mounting for the die face 490 and is 15 connected to a back frame 493 by adjustable struts 494 of the same kind as the struts 432 and 435 for the female die sections illustrated in Figure 26.

An inner wall 495 is mounted on stays within the back frame 493 and the upper edge of the wall 495 is 2° connected to the shaped frame 492 by a flexible seal 497. The back frame 493 has a back plate 498 sealed to it which plate is recessed to receive pneumatic ducts 499 which lead into a chamber formed by the die face 490, the inner wall 495 and"the back plate 498, i 25 from a manifold 500 which is connected through a valve 501 to a pressure duct 502 and through a valve 503 to a vacuum line 504. The flexible seal 497 permits adjustment of the location of the male die face 490 relative to the back frame 493. - 58 - Opening of the valve 50]5 connects the chamber within the die to the vacuum line and is effective through the perforations 491 in the die face to help such o sheet being bent against the surface of the die.

When bending is complete, as will be described, with the valve 503 shut, opening of the valve 501 provides a puff of air through the perforations 491 to help release the bent glass sheet from the surface of the male die upon opening of the dies.

The back plate 498 of the male die is hung from the aal* die support using an adjustable locating and clamping arrangement of the same kind as illustrated for the female die in figure 20 to 22. Further angular rotation about a horizontal axis generally at right angles to the back plate 498 of the die is possible since the male die support unit 291 is adjustably connected to the male die actuator unit 289 in the same manner as for the female die as Illustrated in Figure 22.

Two limit switches S13 and S14 are mounted on a plate 506, Figure 11A, fixed to the side of onet of the support beams 286 which support the male die actuator unit. The switches are actuated by strikers fixed beneath a plate 507 cantilevered from the side of one of the box girders 400 of the male die actuator unit. These switches -and strikers are located so as to give the following indications. 513 - male die partly out 514 - male die in 40255 CLASS LIFTING FINRERS Tho bottom edge of the fDot glass cut to a wind-rcrccn shnpo usually has a slightly concnvo shape which is reflected in a matching shape of the male and female dies. As the carriage 12 and the glass sheet 9 move into the tilting box inward movement of the fomale die begins under timed control as will be described. The rollers in the tilting box are slowed as tho hot glass sheet moves between the bending dies and just before the carriage 12 has come to rest against the carriage stop 242 the glass is lifted from the shoulders 150 on the carriage and is supported between the die during bending on lifting fingers mounted at the bottom of the female die. There are two lifting fingers 510 one at each end of the female die 15 and in Figure 4 the lifting fingers 510 are shown positioned below the lower edge of the glass sheet close to the curved corners of that lower edge.

Initially when the female die 15 is retracted both the lifting fingers are at a slightly downwardly sloping angle for example 2° below the horizontal so that they can be readily moved into position beneath the lower edge of the glass sheet. When the fingers 510 have been raised in a manner which will be described they lift the glass sheet upwardly clear of the shoulders 150 on the carriage so that the carriage can then be rapidly accelerated, by acceleration of the roller."? .in the tilting box, out through the exit 202 from the tilting box onto the extension of the conveyor at the left-hand side of the apparatus as indicated in Figure 1. "60 ~ 40255 Tho locating und actuation of the lifting finger 510 at one side of the female dio io indicated generally in Figure 23 and in more detail in Figures 25 to 29.

An indentical lifting finger and operating mechanism is associated with the other bottom corner of the female die.

As shown.in more detail in Figure 25 each of the lifting fingers 510 is mounted from the female die by means of a mounting which includes an L-shaped bracket 512 which is positioned on the outer side of two of the threaded rods 433 which form part of two of the adjuster assemblies for a side section 425 of the female dies. The bracket 512 is strengthened by a web 513 and is attached by bolts 514 to a clamping plate 515 positioned on the other side of the two threaded rods 433.

A bearing block 516 is attached to the foot of the bracket 512 and carries a shaft 518 to one end of which there is fixed a sleeve 519 which is integral with the lifting finger 510. The other end of the shaft 518 projects from the bearing block 516 and carries a spacer sleeve 520 and has an upwardly extending crank arm 521 fixed to that end and located in position by a grub screw at an angle slightly greater than 90° to the lifting finger 510. When the crank arm 521 is vertical the lifting finger 510 is at small angle e.g. 2° below the horizontal. An upwardly extending spike 522 is fitted into the top end of the crank arm 521 and a ring member 523 which 40285 forms tho termination of an actuating rod 524, Figuro 23, fits over tho spike f>22. Tho actuating rod 524 passes through a seal, not shown, in the rear wall 257 of the tilting box, and is-connected to an actuating 5 mechanism mounted on the side of one of the beams 400 of the female die actuator unit.

Figures 28 and 29 show in more detail the actuating mechanism for the actuating rod 524. A base plate 524a is bolted to the outer side face of one of 10 the box girders 400 of the female die actuator unit.

A tubular boss 525 fixed to the base plate 524a ctrrittv a mounting plate 526. A shaft 527 is fixed into the tubular boss 525 and extends outwardly and carries on its outer end an actuating arm 528 to which the other 15 end of the actuating rod 524 is attached.

A cam follower lever 529 is also pivoted on thti shaft 527 and the outer end of the cam follower lever is formed as a lug 530 which moves between adjustable stop bolts 531 which are screwed through lugs 531a 2o fixed to the mounting plate 526. The positions of the stop bolts 531 limits the extent of rotation of the cam follower lever 529.

The other end of the cam follower lever 529 carries a cam follower roller 532 which rides on a 25 cam plate 533 which is supported by a mounting bracket 534 carried by a sub-bracket 535 bolted to the vertical web of one of the support girders 296. The mounting bracket 534- includes a vertical flange cooperating with an end flange on the sub-bracket 535 3o and is attached to the end flange of a bracket 535 by - 62 40255 means of boltn 536 which extend through vortical nlots 537 in the vertical flange of bracket 534. At tho lower end of the vertical flange of bracket 534 there is wolded a lug 538 which is drilled to recoivo n 5 tlm*ndod rod 539 which lias a ring member 540 at Jtu upper end which fits over a stub bolt 541 which iu fixed to the end flange of the sub-brackot 535 and extends through a vertical slot cut in tho vertical flange of bracJcet 534. Adjuster nuts 542 are fitted 10 on the threaded rod 539» one on either side of the lug 538* When the bolts 536 are loosened the height of the mounting bracket 534 and hence the cam plate 533 can be adjusted by turning the adjuster nuts 542 on the threaded rod 541. 15 The mounting bracket 534 has an upper horizon tal mounting flange 543 on which the cam plate 533 3s mounted by studs 544 fitted into the lower face of the cam plate 533 and extending downwardly through horizontal slots cut in the mounting flange 543. A 20 nut on one of the studs 544 clamps the cam plate 533 to the plate 543. The other stud 544 extends downwardly through a spacer sleeve 545» a ring member 546 on one end of a threaded rod 547 and a locking nut 548. The other end of the threaded rod 547 passes 25 through a lug 549 which is welded to the mounting flsinge 543. The extension of the rod 547 through the lug 549 ia secured by means of lock nut3. This arrangement permits the position of the cam plate 533 to be adjusted horizontally. - 63 _ 40255 i A vertically positioned pneuamtic cylinder 550 la mounted on the plate 526 by means of a pivot fork 551 whose buao is secured to a flange 552 on the plate 52G. A,spindle fixed in the fork 551 carries 5 pivotally a lug 553 on the head of the cylinder 550* The ram 554 of. the cylinder has a shaft 555 fixed in its lower end* which shaft carries a striker plato 556 which projects horizontally to engage an actuating roller of a limit switch S15 mounted on the plate 526. 10 Tho lower end of the shaft 555 carries a bifurcated coupling 557 between the arms of which the cam follower lever529 fits. Tho lever 529 is coupled in tho coupling 557 by a pivot pin.

The actuating arm 528 is, as shown, in the form 15 of a plate member having a central hole which passes over the ohuft 527 and formed with a clamping slot 558. A clamping bolt 559 passes through the separated upper purts of the plate to clamp the plate onto tho shaft. A rod 560 is fixed into the lower end of 20 the plate 528 and extends downwardly and is formed at its lower end a3 a ring member 561 which fits over the outer end of the actuating arm 524 and is secured thereto by lock nuts 562 which thread onto the outer threaded end of the shaft 524. 25 When the dies are open and the female die is .t'ully withdrawn the roller 532 rests on the highest part 565 of the cam plate 533, the cylinder 550 being uupplicd \.*i th air under pressure to apply downward prcooure on tho ca:a follower lover 529, The actuat-30 ing arm 5^ is extended into the tilting box bo that - 64 - 4 0 2 5 5 tho lifting fingor 510 is in ito downward position ready to novo beneath the lower edgo of a glass sheet.

During tho bonding opuration tho female die * actuator unit movoa forwardly and at the point during 5 itn travel when tho ooctionaliaed frame of tho fcraalo bending die pussoo botweon the upright rollers 18 in the tilting box, the downwardly extending lifting fingers 510, one at eaoh side of the die, pass beneath the lower edgo of the sheet. As the advance 10 of the female die continues and the die frame sections contaot the glass sheet which Is resting against the rollers 18 and push the glass sheet away from contact with the rollers, both cam follower rollers 532 ride off the highest points 565 of the 15 cam plates 533 and run down the sloping leading faces 566 of the cam plate under the action of the loading pneumatic cylinders 550. The cam follower levers 529 rotate clockwise up to tho limit Imposed by the upper stop bolts 531, and rotation of the actuating plates 20 528 clockv/ise withdraws the actuating rods 524 which pull the spikes 522 on the crank arms 521 backwardly to raise the lifting fingers 510 against the bottom edge of tho glass sheet 9 and pick up the glass sheet 9 from tho carriago 12. 25 The male die has already been brought into its forward bending position, and during its continuing forward movement the female die carries the hot glass sheet 9 now seated on the lifting finders 510 into engagement with the stationary male aie. Forward 30 movement of the female die continues to complete the - 6 s 40283 bending operation. Just prior to completion of the forward movement of the female die the rocking frame ia tilted back to the horizontal position to bring the dies to a vortical position and gripping tongs 5 are engaged with the upper edge of the bent glass sheet as will be described.

After bending when the bending dies are withdrawn the lifting fingers 510 are returned to their lowered position by switching off the air supply to 10 the cylinders 550 to cause anti-clockwise rotation of the cam follower levers 529 thereby advancing the actuating rods 524 and rotating the lifting fingers 510 to their lower inactive position.

When bending sheets of thin glass, for example 15 up to 3 mm thick, the two lifting fingers 510 at the bottom corncrs of the female die are sufficient to bear the weight of the glass sheet for the time in which it is carried by those fingers as the bending dies close. For the bending of glass sheets of the 20 greater thickness an additional lifting finger centrally of the glass sheet may be provided on the male die actuated by a mechanism similar to that just described, or which may be operated directly by an hydraulic cylinder. The position of such a 25 finger is indicated at 5.10a in Figure 4. - 66 - TONG BAR AMD HOIST 40255 'fhe tong bar 23 from which six tongs 22 are suspended and tho hoist mcchanism from which the tong bar i:: susperidr-tl are illustrated in more detail in r> KiguiN.-r. *60 and !<2 to 34. Each of the tongs 22 is movable to a location exactly positioned over the upper edge of the bent glass sheet between the bending dies before the tongs close onto the upper edge of the sheet, and each of the tongs is loosely mounted in a 10 tong gate structure, Illustrated in Figures 35 and 36, which is mounted above a vertical pivot secured to or cantilevered from the tong bar.

The tong bar 23 is a straight bar which is'suspended from two hoists each of which is mounted on an overhead j *5 beam structure 570 which is supported on pillars 57i which structure straddles the tilting box as shown in Figure 30. A hoist is provided for each end of the tong bar 23 and each hoist comprises a fixed head frame 572 which is an open cuboid structure including vertical 20 supports and cross supports and having a cross head 573 on the upper surface of which are fixed trunnion brackets 574 in which the head of an hydraulic cylinder, respectively 575a and 575b is mounted by pivots 576. The piston rod 577 of the piston which is slidable 25 in the cylinder 575 extends downwardly through the head of the cylinder and is pivotally linked at 578 to massive lugs 579 which are fixed to a cross head member 580 of a movable frame structure 581 also of open cuboid form which is moveable vertically within ii the fixed head structure 572 by actuation of tho cylinck-r _ 67 - 40255 575. Tho movable fmntr ntruciurc la flxml to vertical shafts 581a which alido in bearings which ore in luga 572a on the head frame 572.

If The piston rod 577 extends through the upper end of the cylinder as indicated at 582 and carries on its upper end a switch actuating member 583 which co-operates with two limit switches S16 and S17 actuated when the piston in the cylinder 575 reaches the limits of its upward and downward movement which moves the frame 581 up and down within the fixed head frame 572.

The frame 581 includes a horizontal base structure 586 which provides a mounting for bearing brackets 587 which carry a shaft 588 on which are mounted two winding drums 589 and 590 both of which are coupled to the shaft 588 by a slipping clutch.

A brake disc 591 is also journalled to the shaft and braking caliper arms 592 ar Fixed below the movable frame 581 is a lower frame indicated generally at 593. The lower frame comprises four suspension girders 594 which extend downwardly from a frame 595 of the movable head 581. Tho lower end of each of the suspension girders 594 is fixed to a bottom plate 596. There are four girders 594 respectively fixed to the corners of the upper frame T>fJ5 and tho bottom plate 596. - 6 8 -- 40285 Two !>97, llu- lower pari:-, of wlilch uri> threaded as indicated ot i>93, extend between and are fixed to. the upper franc 595 and the lower plate 596. The shafts 597 carry a ccntre frame which comprises two vertical members 599 which are joined at their tipper ends by a bridge plate 600 and at their lower ends by a cross member 601. The centre frame is mounted on the shafts 597 by lugs 602 positioned at the ends of the bridge member 600 and which are fitted with bearing sleeves. The lugs 602 support the centre frame on the shafts 597 while permitting vertical movement of the centre frame relative to the shafts 597. Further lugs 603 are fixed to the lower ends of the side members 599 and are located on the threaded parts 598 of the rods 597 by means of nuts 604.

Adjustment of the nuts 604 adjusts the vertical position of the centre frame with respect to the frame 593 which is suspended beneath the movable frame structure 581.

The centre frame carries two guide tubes 606 which serve to guide lifting cables 607 and 608 which are respectively wound on to the hoist drums 589 and 590. Both the cables 607 and 608 pass over jockey guide pulleys 609 which are mounted on spindles 610 supported on a mounting bar 611 which is suspended by struts 612 beneath the movable frame 581. The two jockey pulleys 689'are offset with respect to each other as shown in Fi*^ire 38. The two tubes 606 are similarly offset so that the lower ends of the tubes can respectively engage the upper face of the tong bar 23 40255 fixed to the upper frame 595 and the lower plate 596. The shafts 597 carry a centrc frame which comprises two vertical members 599 which are joined at their upper ends by a bridge plato 600 and nt their lower ends by a cross member 601. The centre"frame is mounted oh the shafts 597 by lugs 602 positioned at the ends of the bridge member 6(X) and which are fitted with bearing sleeves. The lugs 602 support the centre frame on the shafts 597 vhile permitting vertical movement of the centre frame relative to the shafts 597. Further lugs 603 are fixed to the lower ends of the side members 599 and are located on the threaded .parts 598 of the rods 597 by means of nuts 604.

Adjustment of the nuts 604 adjusts the vertical position of the centre frame with respect to the frame 593 which is suspended beneath the movable frame structure 581.

The centre frame carries two guide tubes 606 which serve to guide lifting cables 607 and 608 which are respectively wound on to the hoist drums 589 and 590. Both the cables 607 and 608 pass over jockey guide pulleys 609 which are mounted on spindles 610 supported on a mounting bar 611 which is suspended by struts 612 beneath the movable frame 581. The two jockey pulleys 609 are offset with respect to each other as shown in Figure 31. The two tubes 606 ar# similarly offset so that the lower ends of the tubes can respectively engage the upper face of the tong bar 23 near to the back and front edges of the upper face of the tong bar. The cables 607 are connected - 70 40255 to tho front cdr.o of tho tonr. bnr 23 and the cables 6W ore connor.ted io the back o:! Fircuro 31H shows how tlio upper encln of the p»1di4 t.»ilu?:; nrn Hxnl ti> 1 'no cronr ni-u'.'rr c»01 or tho n-nlro fi\ir.:<». Tho upppi* pm';: of tin* ^ulilp lubr:*. 60f» pass through apertures in the cross moinber 601 and are fixed 1.o the cross member 601 by captive nut*. The guide tubes 606 pass through bearing bushes, not shown, fixed in the bottom plate 5°6 of the movable frame, to permit vertical adjustment of the guide tubes within the movable frame 593 when the position of the lugs 603 on the rods 597 is adjusted. In this way the vertical position of the centre frame . with the guide tubes 606 is adjustable to accommodate the uppermost position and the lowered position of the tong bar 23 to suit different heights of the glass sheets being processed. Appropriate adjustment of the depth of the steps 255, 256 in the roof of the tilting box to accommodate these adjustments of the hoist mechanism is also made as described with reference to Figure 9.

The shaft 588 of tte hoist drums 589 and 590 shown in Figure 30A is connected by a flexible drive coupling 615 to an hydraulic drive motor 616 which is mounted on the cross beam 570 of the overhead support structure. The shaft is extended right along the top of the beam 570 to the right-hand hoist unit whore it is supported in further bearin" bushes 587 anil has fixed ^o it the hoist, cable drums 509 and 590 for tho r.ir:ht«hand hoist unit for the tons bar 23 which - 71 - 40255 is idcnticnl in every rospcct to tho left-hand hoist unit.

The guide tubes 606 which are made of heat resisting?-stainless steel extend downwardly through 5 glands 617 in the roof 254 of the tilting box and locate the tipper face of the tong bar 23 which is suspended within the tilting box by the cables 607 and 608.

In the position illustrated in the drawing 10 the pistons are rctracted in the cylinders ,575 so that the movable frames 581 are in their uppermost position retracted upwardly within the fixed frames 572 and the cables 607 and 608 are wound up on the drums 589 and 590 so that the upper face of the tong bar 15 23 is located against the lower end of the tubes 606 which are themselves in their uppermost position.

The lower parts of the lifting cables 607 and 608 are fitted with sleeves 620 which are located in bushings fitted in the upper and lower ends of 20 the guide tubes 606. The tong bar 23 is fixed to the lower ends of the sleeves 620 and in the upwardly retracted position as illustrated the upper ends of the sleeves 620 project upwardly out of the upper ends of the guide tubes 606. 25 The location of the tong bar 23 in its rai?sed position as illustrated is assisted by a roller 621 mounted on the back face of the tong bar 23 which roller encases in a guideway 622 which depends through the roof of the tilting box from the overhead beam 30 570. ~ 72 * 40255 In tho upwardly rohraoted position of the tong bar which is illustrated the jaws of tho tones 22 are spaced above the position of the upper edge of the bending dies. The 5 lowering of tho tong bar to bring the tong jaws astride the upper edge of a bent glass sheet when it is held between the bending dies is effected by simultaneous actuation of the two cylinders 575 to push the movable frames io 581 and 593 downwardly with the tong bar still tightened against the lower ends of the guide tubes 606 by the hoist cables 607 and 608. The whole of the movable hoist arrangement moves downwardly to reposition the tong bar 23 at 15 a location • where the open jaws of the tongs straddle the upper edge of the bent glass sheet held between the bending dies. The tongs are so located on the tong bar that they are lowered into the spaces between the sections 425, 426 and 2o 427 of the female die, Figure 18, and into corres ponding recesses cut into the upper edge of the male bending die to accommodate the jaws of the tongs. As the tong bar is lowered the tongs are guided into exAct location above the upper edges of the 25 glass sheet.

The guide tubes 606 through which the cables 607 and 608* pass are shown in detail in Figures 31B and 31C. The sleeve 620 which is fitted on -71 - 40285 the end of tho cable 607 paoaoa through a bush 623 welded Into the top of the guide tube G06 and through a specially shaped bush 624 which is fitted into the bottom end of the guide tube.

The lower end of the cable sleeve 620 is welded to an upper adaptor plate 626 which rests on the upper face of a plate 628 of the tong bar and has a hemi-cylindrical boss 626a on its upper surface. The end of the cable 607 which projects from the lower end of the cable sleeve 620 passes through the plate 628 and through a lower adaptor plate 627 below the plate 628. A ferrule is welded to the lower end of the cable beneath the adaptor plate.

The lower face of the bushing 624 is formed with a surface 629 of inverted V-section which receives the hemi-cylindrical boss 626a of the upper adaptor plate 626 when the cable 607 is taut clamping the tong bar plate 628 against the bottom of the guide tubes.

A push rod 630 is housed in the guide tube 606, and extends through a vertical hole drilled in the bush 624. The lower pointed end 631 of the push rod rests on the upper face of the adaptor plate 626 when the tong bar is drawn against the guide tubes. The upper end of the push rod 630 is guided by a lug 632 inside the guide tube 606 and fixed to the rod 630 near its upper end is a radially extending striker arm 633 which passes through a slot 634 cut into the wall of the guide tube. An adjustable screw 635 on the arm 633 engages with a pressure-operated 1 74 40255 uwitch iilU which Ju mounted by a bracket 637 on Ihe out:;ido of tlio &uido lube G06. When tho tontf bar io in i ti; mined position au ind Leaked in tho drawings the rod 630 is pushed upwardly so that the screw 635 disengages from the switch S18. When the tong bar is lowered relative to the guide tube 606 the lower support for the pointed end 631 of the rod 630 falls away, the rod 63O is polled down by action of a spring 638 which connects the striker arm 633 to the bracket 637, and the switch S18 is operated to indicate that the tong bar is being lowered as the cables 607 and 608 unwind.

The other guide tube 606 through which the cable 608 is threaded has differently shaped bushing 639 fixed in the lower end of the guide tube 606and extending below the tube end without a conically formed internal face, thereby providing a lower flat abutment face 640 against which the flat upper face of the adaptor plate 626 abuts when the tong bar plate 628 is drawn upwardly against the lower end of the guide tubes. The adaptor plate 627 for fixing the lower end of the cablc 608 to the front edge of the tong bar plate 620 includes a cable clamp clamped to the end of the cable 608 beneath the tong bar. The clamp can be adjusted on the cable to permit adjustment of the angle of tilt of the tong bar by pivoting about the hemi-cylindrical boss 626a of the adaptor plate 626. This permits exact adjustment of the tong bar v/hen the hoist mechanism is being set up. 40258 « The tong bnr 23 is a bar of rectangular cross-section as shorn in Figures 32 to 34 and plates 628 are fixed to both ends of the bar. Each of the platen 628 is part of a bracket which also includes 5 two side plateq 641 which are welded to the top plate 628, being attached thereto by strengthening fins 642. The side plates 641 extend well below the tong bar 23, and the bracket is attached to the tong bar by a bolt 643 which extends vertically through 10 the end of the tong bar and through the top plate 628.

Figures 33 and 34 show that each top plate 628 has side extensions for fixing the adaptors 626, 627 which attach the ends of the hoist cables 607 and 608 to the plates 628. "15 The tong bar is steadied and guided during an upward and downward movement by means of two guide wires 645. The upper end of each of the guide wires 645 is held in a clamp 646, Figure 313, attached to a lower member 647 of the fixed head frame. The 20 guide wires 645 extend vertically right through "the tilting box and down the sides of the pit beneath the tilting box. At the bottom of the pit the lower end of each guide wire 645 passes beneath a guide pulley, not shown, which terminates in a shackle which 25 is attached to the shaft of a hydraulic cylinder * by means of which the wire 645 is maintained at a required tension. - 76- 40HB3 Attached to each of the top plater. 6.?tt at the ends of tho tong bar, there is a pair of rollers 649 extending parallel to the tong bar. The guide wires 645 pauses between these rollers 649. Similar 3 pairs of rollers 630 running on the guide wires are mounted on a cross plate 631 which is welded between the bottom ends of the two side plates 641 of the bracket.

At both ends of the tong bar there are welded 10 to the side plates 641 near their lower end side extension plates 632 which extend inwardly of the tong bar and carry a pivot pin 633 on which is pivoted a frame comprising two side arms 634 which are pivoted on the ends of the pin 653 which project 13 through the outside faces of the ends of the extension plates 632. One of the side arms 634 has a rearward extension which is fitted with a striker plate 653 to he engaged by a pusher rod for rocking the frame. The arms 654 are connected together at their outer 20 ends by bolts 656 and fixed to each of the arms and extending at right angles thereto in the region of the pivot pin 653 are upstanding plates 657 the upper ends of which are connected by a rod 659 in which there engages screw clamps 660 in which there are clamped 25 the ends of three actuator cables 661 which open and close three of the tongs. Three of the tongs are actuated from' each end of the tong bar. - 77 - Each of the tongs ia preferably constructed as described xlth reference' to Fibres 35 to 30, and the tong j-iws close under the voight of sliding vol f.hts forming n part of ttv.' tong conr.timc Lion with 5 tlio nctuntor r.nMea 6(M pulling the aima fi?4 to tho position shown in Fin"re 32.

Each of the striker plates 655 is engaged by a pusher rod*'662, which, as shown in Figure 30, is slldablo in a bracket 663 fixed to one of the 10 vertical members 594 positioned beneath a pneumatic cylinder 664 which is also fixed to the member 594 and whose downwardly extending ram 665 can, when extended, press tho pusher rod 662 downwardly to engage the striker plate 655 and cause the arms 654 15 to rotate thereby tensioning the cables 661 and opening the tong jaws.

A striker plate 666 engages a limit switch S19 when the ram 665 is withdrawn into the cylinder and the tong jaw3 are closed. Identical pusher rod ;>0 arrangements are provided associated with the two ends of the tong bar, each having a pneumatic cylinder 664 and limit switch S19.

Also mounted on the tong bar 23 near each end are downwardly depending bracket arms 667 carrying p r, square metal plates 668 which are employed for sensing phot.electrically the location of the tong»bar during its downward travel below the tilting box.

T0 :r. A*D ' OHO SP.'IP-T.'SION .Six pairs of tongs 22 are suspended from the ■•■n tong bar 2? and 'he suspension for the tongs is such _ 78 _ 40255 that when n. bont glass sheet is held between the dies, the tone bttr descends with the tongs positioned with their jnws open to strnrt'.llc accurately tho upper cdtf«* of the bi Each of the outermost ton/js 22 ir. suspended in a tone, r.ato which ic pivoted on an arm 670 mounted at right angles to.the tong bar.which cantilevers tho pivot out from.the tong bar 23 towards the male die. The next innermost pair of tongs 22 are suspended in tong gates whose pivots are directly connected to the tong bar. The innermost tongs 22 are suspended in gates which are pivoted on the ends, of the cantilever arms 672 which are cantilevered at right angles to the tong bar 23 backwardly towards the female die.

Referring to Figures 35 to 38, each tong gate comprises a vertical pivot rod 673 which is either bolted directly to the bottom of the tong bar 23 or is bolted to a cantilever arm as just described.

The tong gates are thus brought more nearly into a location in which the tong jaws will overlie the upper edge of the bent glass sheet. For example, the tongs for gripping the upper edge of the sheet near tho sides of a sheet bent to conform to the desired shape of a motor vehicle windscreen having sharp end curvature, may be cantilevered well out from the tong bar 23.

The pivot rod 673 is threaded at its upper end which is of reduced diameter as indicated-in Fig. 36 which part of reduced diameter fits through vertically aligned bushes 674 which are welded to 40295 the upper and lower faces of tho tong bar 23.

The tor;: gate which hinges on .the vertical pivot rod 673 comprises a vertical plate member 675 which carries hinge plates 676 and 677 on its back face, respectively at the top and near the bottom of tho plate.' Bearing sleeves. 670 und 679 in the hinge plates pivot the plate member 675 on the pivot rod 673. The bearing sleeve 679 which is fitted in the lower hinge plate 677 has a lower annular flange 680 which bears against a collar 681 which is fitted on the pivot rod 673 below the bearing sleeve 679 thus locating the plate member 675 of the tong gate vertically on the rod 673. The collar 681 is fixed to the rod 673 by a dowel pin 682. A second collar 683 is fixed in position on the lower end of the rod 673» by a screw 684 engaging with an annular groove 685 around the lower end of the pivot rod 673.

A pin 686 extending transversely from the back face of the lower erd of the plate member 675 of the tong gate engages with a slot 687 in the collar 683» which slot 687 is of greater arcuate length than the diameter of tho pin 686 thus allowing the tong gate to hinge on the pivot rod 673 wi"Qiin limits defined by the arcuate length of the slot 607.

A support bar 688 for the upper end of• the tonpa is welded to and extends transversely from the upper end of the front face of the plate member 675. A support bar 689 for the lover end of the tongs 80 ~ is carricd by a support ctructure including a plate 690 which is fixed to the front face of the plate member 675 of the tong gate by bolts 691 which extend through a longitudinal slot 692 in the plate member 675 arid are screwed into a backing plate 693 positioned behind the plate member 675.

A bracket 694 is welded to the lower front face of the plate 690 and carries a downwardly extending leg 695, to the lower end of which the lower support bar 689 for the tongs is welded.

The tongs comprise a suspension member which has a tubular upper part 696 which is threaded at its upper end as indicated at 697 and is secured in an aperture in the upper support bar 688 of the tong gate by means of locking nuts 698.

A collar 699 is welded to the lower locking nut 690 and tho tubular part 696 extends through a bore 700 in the collar. The bore 700 has a widened lower part 701, and the collar 699 has a lower flat abutment face 702.

Just below the collar 699 the tubular part 696 terminates in a tongue 703 which fits into a fork 704 at the upper end of a short link 705. The tongue 703 is coupled into the fork 704 by a pivot pin 706.

The lower end of the link 705 is formed as a tongue 707 which is at right angles to the tongue 703, and which engages in a fork 708 on the upper end of a bar 709 which constitutes the lower part of the suspension member. The tongue - 81 _ 40255 is coupled into the fork by a pivot pin 710 which is at right angles to the pin 706.

The bar 709 is thus linked to the upper part 696 of the suspension-by means of a joint permitting swinging of tho bar,' and of the tongs carricd on the ■ bar, in two directions at right angles. Near its lower end the bar. 709 passes freely through a slot-shaped aperture 689a in the support bar 689.

The tongs comprise a pair of straight tong arms 711 and 712 which are pivoted together by a pivot pin. The tong arm 711 is fitted with an inwardly extending bifurcated hinge bracket 713, Figure 37, having two parallel arms 714, the tong arm 711 being welded or brazed in a slot in the hinge bracket 713.

The tong arm 712 is similarly welded or brazed in a slot in a bifurcated hinge bracket 715 which has two parallel arms 716, and the ends of the arms 714 extend outside and overlap the ends of the arms 716. The pivot pin 717 which pivotally connects the arms 711 and 712 together, passes through an aperture near the lower end of the bar 709 and through apertures in the arms 714 and 716, and is retained in position by means of stainless steel washers and co-operating split pins. The pivot pin 717 for the tong arms 711 and 712 is thus fixed in the vertical sense relative to the tonz bar 23 nnd there is no vortical movement of thi; pivot pin 717 as the tong jaw:i are opened or clo:;cd. - 82 40255 The tong urron 711 and 712 extend below the brackets 71.3 and 713 to forar the Jaws of the tongs which jawo,carry actually adjustable tong pins 711a and 712a of heat-resisting steel. The tong pins aro-screwed into threaded bushes .718 which are formed. at. the *iower ends of the jaws and the pins are. held in position by lock nuts.

The depth of penetration' of the points of the tong pins 711a and 712^ into the surfaces of the glass sheet 9 is determined by the settable stop bolt 719 which is screwed through ah aperture in one of the tong jaws. The length of extension of tho stop bolt 719 from one tong jaw towards the other sots the gap between tho points of the tong pins 711a and 712a when the tongs are gripping the glass sheet 9.

In this embodiment the weighted slider includes a sleeve 720 which is slidable on the bar 709. A tubular weight 721 is clamped on the sleeve 720, the parts of the weight being joined by bolts 722 and being located by a dowel 723. The bolts 722 clamp the two parts of the weight to the sleeve.

The bore through the sleeves 720 has a widened upper part 724 which surrounds the articulated link 705 when the sleeve and weight are in theif lowermost position to permit movement of the joint about both pivot pins 706 and 710. 40255 , An inverted U-shaped strap 725 is welded at \ Its lower ends to tho outer surface of the tubular weight 721 and tho. multlstrand cable 661 for.opening the tongs is attached to, tho top of the strap. The 5 cable is threaded through a guide tubo 727 which is attached to the bottom of the tong bar 23.

When the cable is tensioned to open the tong j..wa tho weight 7?1 in rained until the upper face 728 of a radial flange 729 on the upper end of the 10 sleeve 720 abuts against the lower face 702 of the fixed collar 699* In this position the sleeve 720 fits closely around the articulated link 705 so that the suspension bar 709 is effectively locked solid with the fixed upper tubular part 696 of the 15 suspension.

The suspension member is thus rigid when the tong jaws are opened and the tongs are being located over the upper edge of a glass sheet, but is free to move relative to. its fixed suspension when the tong 20 jaws are closed on to the sheet, while the spacing of the pivot 717 of the tongs from the fixed suspension does not vary.

The upper end of the tong arm 711 is freely pivoted to a bifurcated tong link 730 which is formed 25 with two parallel arms 731 which extend inwardly. A pivot pin 732 extends through the tong link 730 and tho upper end of the tong arm 711 is freely pivoted on the pin 732 which is retained in position by means of stainless dteel washers with co-operating 30 split pins. - 84 - 40255 At itr. upper end the tonj; arm 712 io freely pivoted on ;> pivot pin 733 between two spacer washers 73V Also J'rcely pivoted on the endu of the pivot piii -733 on ri llior r.lilivof tin* wn::lu?rr. 7Vi riro two toii|» l'inko 7j>'->. • Tho uouembly of the tong arm 712, tho^sp'acer washers 734 and tong links 735 is held together by stainless steel washers on the aids of the pivot pin 733 with co-operating split pins which pass through holes at the ends of the pivot pin 733* The tong links 735 are bent outwardly and fit over the ends of the parallel arms 731 of tho tong link 730. Pivot pins 736 are fixed to the lower ends of straps 737 which are welded to the outer surface of the weight 721, which pins 736 fit through holes in the ends of the arms 731 and through aligned holes in the ends of the tong links 735. The inner ends of the pivot pins 736 extend into vertical slots formed in the lower end of the sleeve 720.

With the tong bar 23 in its raised position and the glass sheet 9 held between the male and female bending dies which are still in closed position in 46* —-i-bent glass sheet, the tongs are opened by tensioning each cable 661 to raise the weight 721 and sleeve 720 on the bar 709 of the suspension member and thereby raise the tong link pivot pins 736 causing the tong jaws" to open and locking the bar 709 to the member 696. 40255 Tho tong bar is then lowered until the tongs are in position with (the open jaws astride the upper edge of the glass sheet 9 and the cable 661 is slackened which allows the weight to drop. This. •' .... pushes the tong link pivot pins 736 downwardly ' so that the tong jaws close pressing the points of the tong pins 711a and 712a against the. surf aces of the glass sheet. When the bending dies are withdrawn the hot bent glass sheet is suspended vertically from the tones, and the bending dies can be opened and the suspended glass sheet lowered by operating the hoist motor 616.

The articulated joint constituted by the link 705 and its two pivots at right angles permits small swinging movement of the tongs in two, directions at right angles, limited by the dimensions of the slot 689a so that the tong points can swing somewhat relative to tho fixed upper parts of the tong suspension to accommodate expansions and contractions of the suspended glass sheet during further processing by reheating and quenching by immersion in a chilling liquid. 4 0 2 5 3 TONG GUIDING MKANS Means for (gliding tho tones into exact location with tho tong jaws straddling the upper edge of the class sheet as the tong bar 23 is lowered is shown in Figures 23^ and 35. As the tong bar is lowered the tongs first engage tong guiding means indicated generally at 750 mounted-on the tipper member 429 of the base frame which carries the female die sections* There are six such tong guiding means on the base frame of the female die spaced along the member 429.

As the tong bar is lowered each of the tong gates first engages the tong guiding means 750 causing the tong gate to pivot about its pivot rod 673 so as to bring the tong jaws to the vicinity of their required exact location. As lowering of tho tongs continues the tong gates engage against further tong guiding means indicated generally at 751 mounted on the upper edge of the male die. The tong guiding means at 751 is somewhat lower than the guiding means 750 on the female die and effects final adjustment of the positions of the tong gates to bring all the tong jaws exactly over the upper edge of the bent glass sheet as the lowering of the tongs is completed with the tong jaws passing downwardly between the upper sections of the female die and into recesses cut along thiT upper edge of the male die.

Each of the tong guiding means 750 mounted on the female die includes a bar 752 which is mounted from the upper member 'i29 of the base frame of the 40255 female die by legs 753 which are welded to the upper edge of the member 429 of the base frame and to the • • ^ •» . •' bar 752. A. bracket 754 is welded to the upper face of the bar 752 andanintermediate support 5 bracket 755 1s welded to the bracket 754 and carries a cylindrical housing 756 which Is fitted with a shaft 757. The intermediate support bracket 755 has a side flange 758 which Is drilled to. accomodate the cylindrical housing 756 which housing has an end 10 flange 759 which is attached to the side flange 758 by bolts 760.

A support strut 767 extending perpendicularly from the side flange 758 of the bracket 755 engages in a vertically disposed slot 768 in a plate member 15 769 which has a boss 770 on its back face into which the end of the shaft 757 fits.

The plate 769 carries on its lower part a tong guide member comprising a support block 772 which carries the guide block 773 whose outer face is 20 shaped with a downwardly sloping part 774 which is inclined inwardly towards the axis of the tongs leading into a lower vertical part 775 parallel to the axis of the tongs.

Swinging of the tong gate into position is 25 through the agency of pusher members 776 and 777 » which are screwed into holes in an extension 778 of the bottom support bar 609 of the tong gate. - 88 - { 40285 The pucher member 776 hns a domed head .779 which engages with Jtho sloping surface 774 of the tong guide block 773 as .tho tongs are lowered. • v >»Th"e tong guides .on the male die are; similarly 5 . . "mounted^ as - illustrated at the ri&ht-hand ° side of •i. • ' -*«-7 ■ 'i''" " *■ Pigure* 23 and each ^includes a guide block 780 having , a shaped face the upper part 781 of which is downwardly inclined and inwardly sloping towards the axis of the tongs and the lower part 782 of which is vertical and 10 parallel to the axis of the tongs. The pusher member 777 on the tong gate has a domed head 783 which bears on the surface at 781 and 782 as the tong bar is lowered.

The-mounting brackets for the tong guides 15 attached to the male die are indicated at 784 and are of somewhat different construction to match the construction of the male die, being welded to a back frame 493 of the male die.

The guide blocks 773 attached to the female 20 dio arc mounted higher than the guide blocks 780 attached to the male die and the relative position of the blocks is such that the domed heads 783 of the pusher members 777 do not engage the vertical surfaces 782 of the male die guide blocks until the 25 domed heads 779 of the pusher members 776 have moved off the vertical surfaces 775 of the female die guide blocks 773. This avoids any possibility of jamming of the pusher members and the tong gate between the tong guide means. -89 - 40253 In operation with the pusher rods 662 hold ^ . *" * down by extension of tho rnroo 665 from their cylinders ;• 664, Pli;Uro 30, the cablcc 661 are" tenoioned and maintain the jaws of tho tongs open, as the tong1 bar is lowered, and the heads 779 of all the pusher members 776 on the six tong gates engaged with the " " »' • inclined guide faces 774 of their respective guide blpcks carried by the female die.

As the lowering of the tong bar 23 continues by operation of the cylinders 575 the heads 779 of the pusher members 776 ride down the upper inclined guide faces 774 causing the tong gates to swing to bring the tong jaws to approximate alignment above the upper edge of the glass sheet.

If any degree of misalignment remains the heads 703 of tho pusher members 777 will, during further downward movement of the tong bar, engage the inclined surfaces 781 of the male die guide blocks 700 until the heads 783 ride on tho vertical faces 782 bringing the tongs into final and exact alignment with the open tong pins 711a and 712a exactly straddling the upper edge of the bent glass sheet.

When the lower position of the tong bar 23 is reachcd, that is the lower position of the pistons in the cylinders 576, the cables 661 are relaxed and the jaws close onto the glass sheet. - - 4 03B5 The mule and female tending dies, which are at the temperature of their environment within the tilting box which is maintained as nearly as possible the same as that of the glass sheet leaving the furnace, remain closed on the sheet for the period of, for example, five seconds, during which period t' * . * bending stresses which are induced in the glass by the bending operation are permitted to relax and thermal inhomogeneities within the glass are reduced due to tho contact of the glass with the hot bending dies. When the tongs grip the upper edge of the glass sheet the lifting fingers are lowered, and retraction of the female die begins and the bent glass sheet, suspended from the tongs, is still in contact with the continuous surface of the male die.

The valve 501, Figure 24, is opened and air puffed through the perforations 491 in the male die releases the bent sheet from the male die surface, and retraction of the male die begins.

The bent glass sheet is now freely suspended vertically from the tongs and the lowering of the glass sheet for further processing commences. The rocking of the box back to its tilted position begins, ready for receiving the next sheet to be bent, and the retraction of male and female dies to their initial positions is completed. 40255 BOOST HEATING Tho tct.pcraturo to which the glass sheet' is heated during its advance through the furnace which temperature is related to the time of. heating of the 5 glass in the furnace so as to heat the glass without unacceptable deformation as it relaxes against the-upright rollers of the furnace, is also the temperature at which the glass is bent and this temperature in the range 580° to 650°, e.g. 6lO°C is the temperature of 10 the bent sheet of glass released from the bending dies and suspended by the tongs within the tilting box.

It is often desirable, particularly when producing' a high strength glass sheet, that the initial temperature of a glass sheet before toughening should be greater 15 than the bending temperature, e.g. 690°C and prior to the quenching of the sheet in the tank 26 of quenching liquid, the sheet, as it is lowered, passes between boost heaters which heat the sheet to a higher initial temperature from which it undergoes a preliminary 20 surface cooling prior t.o immersion in the chilling liquid.

After bending of the glass, the rams 577 in the cylinders 575 of the hoists are extended downwardly so that the movable frames 593 are at their lowermost 25 poBition relative to the fixed head frames. E^irther lowering of the tong bar during continued processing of the glass takes place by operation of the hoist motor 616 which, through the flexible drive 615, drives the shaft 500 and the cable drums 589 and 590 to unwind 30 the cablc.-u 607 and 608 which suspend both ends of the - 92 - 40255 tona bar. Vortical de-scent of the tone bar along the guide wires 645 commences and the glass passes between the two banks of boost heaters 27, Figure 1, which are shown in more detail in Figure 39. The 5 top of the boost heaters 27 is about 60 cm below the bottom.edges of the dies, and the boost'heater panels are 100 cm deep. * The bonks of boost heaters each comprises a refractory panel 790 which carries a pattern of 10 heating elements 27. The refractory panels 790 form walls of an elongated chamber having an open entrance mouth 791 lying below the exit mouth 269 from the tilting box. Sealing asbestos curtains 792 hang downwardly from the sides of the elongated mouth 269 15 against members defining the mouth 791 into the refractory boost heating assembly. The refractory panels are fixed vertically and the flexible asbestos curtains 792 provide a flexible seal between the mouth 269 of the tilting box and the fixed entrance mouth 20 791.

Each of the refractory panels has a metal support backing structure 793. The heater elements 27 arc in the form of wire wound elements on ceramic tubes which are mounted on steel connector rods 794 25 which are fixed through the refractory panels 790 and are mounted in insulators held by the metal backing structure 793. - 93- 40235 , Tho clcctrical uuppliea to the boost heater el omenta .°7 hre such1 as, to maintain tlio heater olemonto at a tempuraturoin the range 750°C to 1600°C, for example 1000°C to 1200°C. During tho downward passage of the bent'glasa: sheet between the heaters the glass may be heated to 60°C or more above tho temperature at which it leaves the bending dies* for example the glass at 620°C may be heated to a pre-quenching temperature of 680°C. .

If the glass passes downwardly at uniform speed between the heater elements it is heated substantially uniformly throughout its thickness. The surface temperature may be raised slightly higher than that of the core of the glass but at worst a temperature difference of about 12°C is produced between the surfaces and the core of the glass.

Alternatively, and in order to heat the lower edge of the glass sheet to a higher temperature than the upper edge of the glass sheet, the glass may be accelerated when the lower edge of the glass sheet is at the level of the bottom of the heater panels for example, from a lowering hoist speed of 150 mm/sec. to a lowering speed of 300 mm/sec. The heating time for the upper part of the glass sheet between the boost heater panels is therefore less and so, while each part of the glass sheet is heated so that there is substantially no temperature gradient through its thickness or at most about 12°C as just described, a linear temperature gradient is set up from a high temperature of for example, 700°C at the lower edge 40255 j i of Die bent ^Inaa sheet to a lower temperature or for example, fcO°C at tho upper edge of the glass sheet as it pusucn between the bottom of the boost heaters .27 to a pro-cooling stage prior to quenching in the 5 oil tank 26.

The control equipment to be described permits tho setting up of a selected velocity profile for the hoist motor 616 from initiation of its operation to the time the hot bent sheet of glass is brought to 10 rest .in the quench tank.

A maximum lowering speed of 100 cm/sec. can be achieved, and some further examples will be given.

Some more detailed examples of operation will now be given in Table IX which gives the temperature 15 at which the glass is bent as well as times between the boost heaters to heat the glass to a desired pre-quenching temperature and values of hoist speed necessary to achieve the desired temperature. 95- 40255 TABLE IX Glusr. Thickness mm .

Bonding Temp.

°C Boout Heat Furnace Temperature °C Final Class Temperature °C .

Time in Boost Heat (seconds) Hoist Speed in/sec. 2.0 580 750 630 15 2.4 2.0 560 750 650 22 1.6 2.0 620 750 630 3.0 12.0 2.0 620 750 680 25 1.4 2.0 560 1000 630 4.0 9.0 2.0 580 1000 720 12.6 2.8 2.0 620 1000 720 9.3 3.9 2.0 580 1600 720 27 1.3 2.0 620 1600 720 2.1 17.0 3.0 580 750 630 20 1.8 3.0 580 750 650 30 1.2 3.0 620 750 630 5 7.2 3.0 620 750 680 35 1.0 3.0 580 1000 630 5.6 6.4 ' 3.0 580 1000 720 17.3 2.1 3.0 620 1000 720 12.9 2.8 3.0 580 1600 630 1.3 28.0 3.0 580 1600 720 3.9 9.0 3.0 620 1600 720 2.9 12.4 -96 - TAI5LE IX - (Continued) 402S5 ! i ThJcIuiocis .nan . ..

MI'IHI.LII/: Temp.

■ °C f ' lbio::t Hon 1.

Kurnaco Tcmperaturo °C Kiiiu.L UJ.i«U Temperature °C TJinu in Boost Heat (seconds) lluiut Speed in/sec. 4.0 580 . 750 .630 - 26.3 1.4 4.0 620 750 630 6.3 5.7 4.0 650 750 670 16 2.3 4.0 580 1000 630 7.2 5.0 4.0 580 1000 720 22.2 1.6 4.0 620 1000 630 1.4 25.7 4.0 620 1000 720 16.6 2.2 4.0 650 1000 680 5.0 7.2 4.0 650 1000 720 12.0 3.0 4.0 580 1600 630 1.7 21.2 4.0 580 1600 720 7.9 7.4 4.0 620 1600 720 3.62 9.9 4.0 650 1600 720 2.6 14.0 -97 - 40255 Some further examples of operation are given in Tableau x, XI and XII which show.the production of a * linear* temperature gradient of from 10°C to 30°C from a higher temperature of the lower edge of the sheet"to V* y •• • r> "• * / ' • ' « ' a lower temperature of the upper edge of the sheet.

These tables are based on a glass sheet 25 cm in height, the acceleration of which takes place from the initial speed to the final speed when the lower edge of the glass sheet has reached the bottom of the furnace. The hoist speed gives the approximate transit times of the top and bottom edges of the glass sheet between the boost heaters. 98 - TA31S X Glass Thickness ?.o mm Bending Tea?.

Or w Boost Heat Furnace Temp. C .

Final Glass Temperature Gradient °C Time in Boost Heat Seconds Hoist Speed . in/sec. bottom Edge Top Edge Bottom Edge Top Edge Initial Final 580 750 630 620 10 15 11 2.4 . 4.0 580 750 650 620 30 22 11 1.6 6.5 • 580 1000 630 620 10 4.0 3.2 VO • o 13.0 580 1000 720 690 30 12.6 9.4 2.9 _ 4.6 . 580 1600 720 690 30 2.8 2.2 13 19 620 750 680 650 30 25 11 .1.44 9~ 620 1000 720 710 10 9.3 8.3 3.9 4.6 ■ 620 1000 720 . 690 30 9.3 6.3 3.9; . 7.5 620 1600 * 720 710 10 2.1 1.8 17 * 22 TABLE XI Glass Thickness 3.f> mm Bending Te;r:o.

°C Bcost Heat Furnace Tenp. °C Final Glass Temperature °C Gradient °C Tire In Boost Heat seconds Hoisi:Speed . in/sec. 1 1 i 1 Bottom Edge Top Edge ' Bottom Edge Top Edge Initial Final ^ 580 750 630 620 10 20 15 1.8 2.9 560 1000 630 620 10 5.6 4.5 6.4 9.0 580 1000 720 690 30 17.3 13.1 2.1 3.3 580 1600 680 670 10 2.7 2.5 13.3 15.0 580 1600 720 690 30 3.9 3.0 . 9.2 14.0 620 750 640 630 10 10 5.0 3.6 14;4 620 750 680 650 30 35 "15 1.0, . 7.2 620 1000 660 650 10 5 3.6 7.2 12.4 620 1000 720 690 30 12.9 8.7 2.8 ; 5.5 620 1600 680 670 10 1.7 1.4 , 21.2 . 29.0 620 1 1600 720 690 30 2.9 2.0 12.4 23.2"; TABLE XII Glass Thickness 4.0 ran Sending • Tenp.

°C i : 1 Boost Keat Furnace Tenp. oc Final Glass I Temperature °C Gradient °C Time in Boost Keat seconds | . Hoist Speed I ln/sec.

Bottom Edge Top Edge Bottom Edge Top Edge . Initial Pinal V 5eo 750 630 620 10 26.3 20 1.4 2.1 o a) 750 650 620 30 40 20 0.9 V v 3.6 5S0 1000 630 620 10 7.2 5.7 . 5.0 7.3 580 1000 720 690 30 22.2 16.9 1.6 2.5 580 1600 660 650 10 2.8 2.4 12.8 16.4 580 1600 720 690 30 4.9 3.9 7.4 10.4 620 750 640 630 10 12.5 6.3 2.9 11.2 620 750 680 650 30 45 20 0.8 4.8 620 1000 660 650 10 6.2 4.6 5.8 9.0 620 1000 720 690 30 16.6 11.2 2.24 4.2 620 1600 720 690 30 3.62 2.5 10.0 19.0 650 750 670 660 10 16 7.5 2.25 11.1 650 1000 720 ■ 690 30 12 6.8 3.0 '% 8.6 4 0 253 1 I • | PRE COOLING STAGE The two blowing boxes are each elongated. boxes which extend from oidr to aide ol' tho pitlvlow the boost heaters. Each of the boxes 28 with its nozzles 29 extending from the front face of the box is mounted on side wheels 800, Fig* 40, which run on ' tracks 801 which extend longitudinally along the side walls of the pit. Each of the blowing boxes 28 is connected by a duct 802 to a centrifugal blower 803 mounted near one of the end walls of the pit and each of the blowing boxes 28 has an individual supply from its own centrifugal blower 803 at a pressure of 38 cm water gauge. The wheels 800 are the wheels of carriages on which the blowing boxes and their connection ducts are mounted and the blowing boxes can be moved in and out on the tracks 801 to adjust the spacing of the ends of the nozzles 29 from the path taken by the hot bent glass sheet as it is lowered through the bottom of the boost heater elements. A usual separation of the ends of the nozzles is 10.5 cm. The front faces of the blowing boxes 28 may be flat as shown in the drawing or may be curved to a shape nearly matching that of the bent glass sheets which are to be pre-cooled by cooling air directed fijom the blowing boxes. 102- The of Uio Itoy.i-:; ;tri> .In one iinlxjdlini'iil. ?? era. The nozzlo orificcs arc 3 mm in diameter and -there aro nrrunged in a "DOMINO 5" pattern with a pitch of IB nun. The nozzles arc staggered so that they do not face, each other across the - interspace . through which the. glass is lowered.

Attached to the carriage for the right hand blowing box 28 as shown in Figure 40 is a downwardly depending frame 806 which carries at its lower end support shoos 807 onto which the hot glass sheet is lowered. The shoes 807 extend right across the lowering path of the glass and are steadied by stays 808 which are clamped to the track .801 when the blowing box is in desired location. The frame 806 and the stays 808 are sufficiently long to ensure that when the bottom edge of the glass rests in the shoes 807 the upper edge Of the glass is just below the bottom nozzles of the blowing boxes.

The supply of cooling air to the boxes 28 io regulated so that the surfaces of the reheated glass are cooled by, for example 50°C while the core of the glass thickness does not cool appreciably below the pre-qucnching temperature achieved by reheating by the booat heaters. In this way temperature gradients of about 50°C exists from the core to the surfaces of the glnso as the glass leaves the ambience of the cooling air supplied through the nozzles 29 and the glass is then immediately quenched in the quench tank 26. - 103- 4 0 3 5 5 OUENOl TANK The qucnching tunk 26 la illustrated (Ungrammatically in Figure 40 nnd In more detail in Figure 41. The tunk contain:* a body of chilling liquid maintained for cxumple at 240°C, and is surrounded by. thermal insulation 809. The tank 26 is seated on a table 810 which stands on the lifting platform 30 which is the upper platform of a scissors-lift table which comprises a lower platform. 811 and scissor links between the two platforms as shown in Figure 42. The table is operated hydraulically and lifts the quenching tank 26 at a time relative to the operation of the bending dies which ensures that the quench tank has been raised to a position just below the blowing boxes 28 before the glass sheet descends through the blowing boxes into the chilling liquid in the quench tank. Provision is made for the frame 806 with the shoes 807 to bo fully immorsc'd in the quenching liquid before the glass enters the tank.

The quench tank as shown in more detail in Figure 41 is an elongated tank long enough to accommodatc the longest glass sheet being bent and toughened. The elongated rectangular quench tank 26 rents on a girder framework 812 which forms an upper part of the support table 010. A flange 813 around tlio upper edge of the tank 26 is fixed to upper girders 014 of a support structure including uprights 815. The thermal insulation 809 is also fixed to this support structure. An enclosed space is defined in the upper part of tha support table 810 by sheets of "1 Oi " thttimai in:-.u1;iMon 017 :md an olrctric licalpr 010 Jj» inninit«il in l.liln riirl'ojs.tl Ih'Jh\mIli tlio floor oft'llii*' quone li 1,'iiik -■ .'Phlii oi««utrie. Ius»tor. sorvuK toilim.t- tho-jbliLll.lnG liquid in tho tank. - ^p-The.exapt location-of, the surface.of the •. ■' liqtiidl'in which;, the glass is quenched, relative to f%h^ bottom nozzles' of -the bloving boxes, 28 is.. ;of -4n*P9rtance in order to .ensure a minimum decay, of the- centre-to-surface temperature gradients produced through the thickness of the glass by the pre-cooling stage, before the glass surfaces become severly qucnchcd by contact with the chilling liquid. It in tho temperature gradients existing through tho glasn thickncss as the core of the glass cools through +he strain point of the glass which influences generation of desired surface compressive stress and central tensile stress in the glass by the time the glass has cooled to room temperature.

Accurate definition of the exact location of the surface of the chilling liquid, for example 2.5 cm below the bottom of the blowing boxes 28, is provided by causing chilling liquid to flow continuously over a weir in the upper part of the quench tank 26. Tho weir is illustrated in Figure 41 and defines an elongated rectangular slot which opens upwardly towards the interspace between the blowing boxes 28. The weir, indicated at 820 is constituted by the upper edges of vertical side walls 821 and end walls, one of which is indicated at 822. The lower parts of the side walls 821 and of the end walls 822 are - 105 - 40255 flared outwardly as indicated at 023 and terminate in bottom flangou 824 which are bolted to a weir * • - • • ' * • • oupport* frame 825 which is welded* to the inner wall a . g . of the tank 26; near to tho top of the tank. Pads 826 arc welded to -the outwardly flared iportions 823 of tho side wallr. 821 of tho weir. There are four such pads near tho four corners of the tank. A bracket 827 is welded to the lower face of each of the pads and shackles 828 attached to the bracket 827 suspend a cullet basket 829 in the tank beneath the entrance mouth through the weir. The cullet basket comprises a rectangular frame work which rests on the floor of the tank and the sides of which are filled-in with expanded metal mesh. The basket is present to collect any broken glass resulting from shattering of glass which can result from quenching in the liquid. Lilting eyes 830 are bolted from above into the pads 826 to enable the weir construction and cullet basket to be lifted as a whole out of the quench tank when the flanges 824 are unbolted from the support frame 825- Near the base of the quench tank 26 an inlet pipe 831 is provided for the supply of chilling liquid into the tank. A drain pipe 832 fitted with a tap 833 leads from the floor of the tank 26.

The sides walls 821 and end walls 822 of the weir structure define a moat indicated generally at 834 in the upper part of the quench tank. This moat i p defined between the side and end walls 821 and 822 of the weir and the walls of the tank 26. An - 106 - 4 0255 outlet pipe 0y.> leads from tho bottom of the moat H " . • . ' '■ and?is cohrif.-ctcd to a pump, not shown, whoso outlet is connccted back to inlet pipe 831 so that there is a continuous circulation of chilling liquid upwardly through the ^ank . overflowing over the edges 820'of the weir and falling into the moat 834 for recirculation. In the courso of1 this recirculation the chilling liquid, for example, a mineral oil such as CYLREX P H (Registered Trade Mark) is replenished by the addition of fresh oil as necessary. A low boiling point additive may be employed in the chilling liquid, for example carbon tetrachloride or toluene, added to mineral oil in a small percentage of up to 4# by weight.

A vapour extraction mouth Indicated at 836* extends right around the upper edge of the quench tank and is connected to a vertically telescopic duct 8371 which is connected to a manifold leading to an extract fan 860 and a condensate rcmovery unit.

The upper edges 820 of the walls 821 and 822 which define the weir are located above the top of the quench tank so as to present an accurately defined surface of chilling liquid to the glass as it is being lowered through the blowing boxes 28. When the quench tank is raised by the lift table this *■ surface is accurately located relative to the blowing boxes so that the glass is immediately quenched in the chilling liquid as it leaves the ambience of the cooling air. In order to determine the location of the liquid surface at the weir 820 with accuracy, - 107 - 40253 stop mean:; nt e provided in the operating mochanisra of the ccir.uors-lift table accurately determining the upper position of tho lifting platform 30 carrying the quench tank.

Figure 4 2 shows the scissors-lift table in more detail. The lifting platform 30 on which the support table 810 for the quench tank 26 stands is supported from a rectangular base frame 811 by two pairs of scissors links 836 and 837 respectively at either side of the table. The links of each pair are pivoted centrally by a pivot pin 838. The upper ends of the links 836 are pivoted on fixed trunnions 839 carried on tho sides of the platform 30 near one end of the platform. The upper ends of the links 837 carry rollers 840 which run in longitudinal trackways 841 carried by the platform 30. At their lower ends the linko 837 are pivoted on trunnions 842 fixed to the bottom frame 811. The links 836 carry at thoir lower ends rollers 843 which run in trackways 844 extending along the sides of the bottom frame 811.

A cross member 845 is fixed to and extends between tho lower ends of the two links 837. Lugs 846 welded to the cross member 845 carry a pivot pin 847 to which is connected the outer end of an operating shaft 848 of an hydraulic cylinder 849. The other end of the cylinder 849 has a mounting rod 850 which is pivoted in trunnions 051 welded to the base frame 811. Extension of tho operating shaft 848 from the cylinder 049 pivots the links 837 about their lower - 108- 40253 t.runntormM4? nnd tho plaifoint j50 In lifted. Tho bottom rollura U43 on tho links 836 run along the trockwayn 044 until they abutacainst ctop bolts one of which is indicated at 852 which are fitted in stop plates 853 fixed to the bottom framo 811.4 'Adjustment of the bolts 852 determines the height to which the '• a* - . ;• ' •'* •- 5'" . ' platform,30 can be raised and therefore accurately determines the position of the surface of the chilling liquid flowing over the weir 820 relative to the lower nozzles 29 of the blowing boxes 28.

A limit switch S20 fixed to the bottom frame 811 is operated by a striker plate 855 which is fixed to the lower end of one of the links 836 as illustrated. This limit switch S20, as will be described is connected in the electric control circuit for controlling operation of the hydraulic cylinder 849.

At the appropriate time in the operation of tho apparatus the cylinder 849 causes the platform 30 to lift to carry the quench tank 26 to its raised quench position ready to receive a hot glass sheet. The quench tank remains in position with the hot glass resting in the shoes 807 for a time, for example 20 scconds, to ensure that the whole of the glass has cooled to a temperature well below its strain point before the shaft 848 is retracted into the cylinder 849 to lower the platform 30 which thereby lowers the qucnch tank from around the supported bent glass sheet which is indicated at 856 in Figure 40 and remains seated on the shoes 807.

During quenching, as soon as the whole of the - 109- 40288 glass is immersed in the chilling liquid and the lower edge of the glass 856 is seated on tho shoes 807 the tongc' are opened by actuating moans in the pit engaging the striker plates 655, Figure 32, thereby 5 tensioning the tong operating cables, and the tong bar 23 with the tong3 22 is then raised by operation of .the heist mechanism so that the tong bar is in position above the dies before the dies are closed onto the next glass sheet to be bent. 10 After the quench tank has been lowered the bent glass is removed manually to a degreasing tank and after degreasing the glass is cooled to room temperature.

When a series of bent annealed sheets of 15 glass arc to be produced the quench tank 26 remains in its lowered position, the boost heating section is switched off and che air supply to the pre-cooling section is turned off.

In one embodiment the frame 806 is mounted in 20 an annealing enclosure which is moved horizontally into position to receive each sheet in turn as it is lowered through the inoperative boost heating and pre-cooling sections. The frame is spring loaded to accommodate the highest speed of the glass which 25 will not have been damped by immersion of the glass in a chilling liquid. The shoes 807 of the frame are provided with greater thermal insulation.

Each sheet in turn rests on the shoos 807 in the annealing conditions within the enclosure 30 so that v.'hon the glass is cooled only relatively small _ no _ ,40255 ! I stresses are present, as represented for excunpl'b by O a central tfnsile stress of 70 MN/ra . When the (sheet hns coolcd the annealing enclosure is moved away horizontally, the annealed sheet ia removed from the frame, and the annealing enclosure is returned • •.# ' ■ . -into position ax-ound the frame ready to receive the next sheet.

In.some circumstances an annealed sheet is manufactured in succession to a toughened sheet, for example when those two sheets are to be laminated together to produce a laminated windscreen, and a modification of the apparatus for this purpose is described with reference to Figures 48 to 50. 402 55 TTi.'i'i :*c HMY 'ryrnAUUr criruiTS Figure A3 Illustrates dlnr.rniamaticnlly the hydraulic circuits for operation of the female and male die actuating cylinders All and Alln, the rocking frame actuating cylinder r> . jJOl ( the cylinders 57!>a and r>7rA> for raisin,? and lowering the-moveable frames which carry the tong. bar suspension ; system, 'and the cylinder 849 operating the scissors-lift table. /The control of the motor 616 which operates the * ' * hoists from which the ends of the .tong bar are suspended, 10 is also shown.

. A main supply line 183 of hydraulic fluid under pressure, provides the:supply of hydraulic fluid for these cylinders. The ends of the female die actuating cylinder All are connected by lines 870 and 871 to a solenoid opera-3 5 ted spool valve 872 which is also of the "locked centre1* type and ha.s-operating solenoids 873 and 874. V/hen both the solenoids «73 and R74 are de-energised, the spool of tho valve is locked in a central position blocking fluid flow and maintaining the cylinder under whatever con-20 ditlons currently prevail in the cylinder. Inlets to the valve 872 are connected to the pressure line 183 and the return line 1^3.

The ends of the male die operating cylinder 4lla are connected by lines 875 and 876 to a "locked centre" 25 directional spool valve 077 having operating solenoids 878 nnd 879. The inlets to the valve 877 are connected to both tho pressure line 1«3 and the return line 1^3.

The ends of tho rockinr: frame cylinder 301 are connected V' lines ,8.*W) and 881 to outlets from another 7-0 "locked centre" directional spool valve 882 which has - 112 ~ ( 40255 n|'e»7«l.1i'/T nolnno^Oa rrw ntul r.!V« nnri which in cnnncc'cd to .tooth tho prc.-«:;ure lir.o 1A3 nrul tho return lino l'VJ.

A further "looked centrc" directional spool vnlvc M7, hnvinp onrxnUn/r Wlrnoldo »W. nnd W), nn Input, •line connected to the-pressure line 183 nnd an exhAust line;connected "to the return line -193, has a line 890 coranected to the upper, end of the left hand vertical cylinder.575a of thehoist mechanism of Figure 30. The, lower end of the cylinder 575a is connected by a line 891 to a compensating spool valve 892 having operating solenoids 893 and 894 and a pressure line 895 connected to the pressure line 183 and an exhaust line 896 connectcd to the return line 193.

The upper end of the right-hand cylinder of the hoist mechanism, here designated 575b is connected by a line 897 to one input of the spool valve 892, which valve is operable to connect the lines 891 and 897 in series in circumstances +o be described to ensure that both ends of the tong bar are brought down together. The lower end of the cylinder 575b is connected by a line 898 to the valve 887.

The ends of the sclssors-lift table cylinder 849 are respectively connected by lines 899 and 900 to a further and similar spool valve °t01 having operating solenoids 902 and 903, which valve is also connected to the pressure line 183 and the return line 193.

The hoist: motor 616, Figure 30A, is connected to the pressure Hmo 183 and the return line 1°3 by a directional spool valve f,0/> having operating solenoids °0C. nrd 006. One output from 1lv; valve on line °0? is - 113 " 40253 pres.n.ri r.c«l to la-lve the i.in'or ClG in a diivci.lon to lower Uto tor-: !>ir. The other outnut lYom tl:e valve °0A is connected hy a lino P0Q to ti e other sido of the ir.ol.or, awl when pressurised drives the hoist motor 616 in a direction to raise the tons bar. . The speed of tho motor is controlled by a shunt circuit connecting the valvo r Variation of the setting of the valve 900 to control, the speed of the motor 616 is achieved pneumatically as described with reference to Figure.AA.

VI}.TING BOX KiiEWlATIC CIRCUITS Pneumatic control circuits associated with the tiltinp box are illustrated diapr aroma tically in Figure AA.

The* upper avid lower ends of the two cylinders 664, Fif^iro 30, which depress the pusher rods 662 to open the tonp;s, are connected in parallel to a solenoid operated spool vnlve 911 which hns input connected by a line °12 to an air pressure line °13.

The valve °11 has operating solenoids 91A and 915, When air under pressure is switched the tops of both cylinders 66A the pusher rods 662 are depressed and the i.on^ ;)iwa open, .*uid vice versa \:hci pressure air is switched to tho i.ottoms of the cylinders downward force is rcrovnd from the pusher nnd t)ie •'on.^s close.

Figure A also shov.*.\; ore pneurniic circuit for oprrat1'!!;' the i'ar.c hra'w 591 associated with the hoiut ~ 114 40888 ilri'i Fi/mro *0. Itipumntlcnl ly op#»r:? t;rd caliper oris for <:i;;nnlu»T 'he brnkc rli ;;c r,rn arc coniiec.UM by n line pl? .> an Mr rese^v^ir 'V17 which is supplied V '' • a, rcj^n n tor ./Ufl from pn ml lei Mfh oressiire and low presnure circuits v/hone input.s are connected to the.pressure line 913. /.

The Mgh pressure circuit# whose function is to enlace the.brakes and hold the-hoists in wound-up' condition until the gripped glass is to be lowered from the bending dies, comprises a pressure regulator 919 and a spool valve 920 having an operating solenoid 921 energisation of which releases the brake.

The low pressure circuit is similar, having a low pressure regulator 922 and a solenoid-operated spool valve 923 having a solenoid 924 energised for a low pressure condition and a solenoid 925 energised for a zero pressure condition as will be described.. The function of the low pressure circuit is to prevent "snatching" of the hoist winding gear when lowering a bent glass sheet.

The speed control hydraulic valve 909 for the hoist motor 616, Figure 43 ia operated by a lever arm 926 which can assume three positions, marked A, B and C in Figure UUt each setting a motor speed, under control of a double acting cylinder assembly comprising two cylinders °27 and °28 which are joined end-to-end and slidable as a whole in a fixed housing 92Q.

The cylinder °27 has a piston ^30 mounted on a piston rod °?1 whose outer end carries a domed head 'y3? which ennnres the lever arm °26 of the speed control "115 - 40258 valve 909.

The cylinder 928 has a piston 933 on a piston rod 934 whose outer end is fixed to a fixed bracket 935• The inner and outer ends of the cylinder 927 are 5 respectively connected through flow control valves 936 and 937 to a isolenoid operated spool valve 939 having a single operating solenoid 940 and connected to the pressure air line 913. Energisation of solenoid 940 sets the jmeuoatic circuit to determine a first motor 10 speed. The Inner and outer ends of the cylinder 928 are similarly connected by flow control valves 941 and 942 to a further spool valve 943 having a si-^jle operating solenoid 944. The valve 943 is al3o connected tc the pressure line 913» and en*.r«risatJ cw of the solenoid 15 944 sets a second speed of the hoist motor 616 as will be described.

BENDING AND TOUGHENING OPERATION When a previous die bending operation has finished, the dies are fully withdrawn, the tilling box is in its 2o inclined position to receive the next hot glass sheet, lowering of the glass has begun, and contacts R122 and R123 of the hoist lower relay R12, Figure 47, close. The motor and the rollers are accelerated to fast speed, and energisation of the relay R12 operates a circuit 23 including a solenoid which removes the carriage stop 242, Figure 9, and the carriage is accelerated out of the tilting box.

When the front of the carriage approaches the end of the exit section of the conveyor it opens a switch 30 which, as described in the above-mentioned co-pending Application is effective to return the roller driving motor to creep speed. - 116 - 40388 All the rollers 8 and 13 In the furnace and In the tilting box are all now being driven at creep speed; and at the same time contacts open to disengage ,the clutch driving the rollers of the 5 exit conveyor which are then brought to rest so that the carriage is stationary on the exit section of . the conveyor, and can be removed and taken back" to the inlet end for reloading. The reset push button switch is then closed to start lo up the whole operation for processing the next sheet.

The initial condition of the apparatus is that both the male die and the female die are withdrawn, -the tong bar is raised and the tilting 15 box is inclined, e.g. at 5° angle. - 117- 40255 The malo die actuating cylinder 411 a, Figure 43> has been operated to retract the male die by energisation of solenoid 878 of the valve 077, Figures 43 and 45, through normally closed contacts R73 of a mole die relay R7 which also has ✓ t '■> . holding contacts R71 and normally open contacts R72 in series with solenoid 879 of the vaire 877.

Energisation of solenoid 878 normally holds the male die out.

Similarly the female die actuating cylinder 411 is operated by female die relay R8 having holding contacts R81 normally open contacts R82 in series with the solenoid 874 of the valve 872, and normally closed contacts R83 in series with the coil 873 of valve 672. Energisation of solenoid 873 normally holds the female die out.

The tilting of the tilting die box is controlled by a roller vertical relay R9 having holding contacts R91 normally closed contacts R93 in series with solenoid 883 of the cylinder 301, and normally open contacts R92 in series with solenoid 884 cf the valve 882. Normally the solenoid 883 is energised so that the cylinder 301 maintains the frame in its inclined position.

A tong bar relay RIO is In series with the hoist raised switches S16, Figure 30, and rollers vertical switch S8, Figure 12, and the female die in switch S10. The relay RIO has holding contacts R101, and normally closed contacts R102 in series with solenoid 689 of the valvo 887, Figure 43. In parallel with the solenoid 009 is the solenoid 893 of the compensating - 118 - 40255 valve 892, which solenoid 093 is in series with two parallel hoist raised switches Sl6 which are respectively on the left-hand and right-hand hoist mechanisms of Figure 30 Relay RIO'eilso has normally-open , contacts R103 in series with solenoid 888 of the valye 887. In parallel With, solenoid 888 is solenoid 894 of the compensating valve 892 which, solenoid 894 is .connected in series : withtvo parallel hoist lowered switches S17.

With the tong bar rising in a mid-position coil 889 is energised and the hydraulic circuits for the two cylinders 575 are connected In series with pressure fluid fed on line 898 of valve 887 to the bottom of cylinder 575b. Fluid under pressure from the top of cylinder 575b passes on line 897 and through the compensating valve 893 on to line 891 connected to the bottom of cylinder 575a.

The two pistons in the cylinders 575a and 575b rise together but may not reach the top of their stroke together. Whichever hoist raised switch Sl6 closes first energises solenoid 893 of the compensating valve 892 which changes over to connect pressure fluid directly to the bottom of cylinder 575a thereby ensuring that both hoist frames are in their raised position as nearly as possible at the same time.

When the tong bar is being lowered, the gr^pper bar relay RIO is energised to open contacts R102 and close contacts R103 which energises coil 888. The compensating valve 892 is in position to connect the two cylinders 575 in series. Pressure fluid is fed on line 890 to the top of cylinder 575a and from the bottom of that cylinder -119 40255 * . 4 cn line «''OI -the vnlvo l''t? to tlio top of the cylinO'.-r" r»'/r»b. './hqn one of.the cylinders reaches the .bottom" of its stroke one of the hoinl. lowered switches ni7 ;in;.closod to energise solenoid BOA to < swjlrh'ovcrthe compensating valve 002 so that pressure fluid in fed-fron line 005 to lino 897 to the top of cylinder 575]! and both the cylinders 575 are brought dovm togetherto tiring the. tong bar horizontally into position above the closed bending dies.

A male'die timer which was actuated when the sheet was in the furnace now commences the actuation of the male die and after a delay, closes the contacts T3» Figure A5 which are connected in series with the female die partly out switch SO and the coil of the male die re3 oy R7 whose, holding contacts R71 are in parallel with the switch T31. Actuation of the relay R7 causes contacts R73 to open and contact R72 to close so that solenoid 078 of valve 077, Figure A3, is de-energised and solenoid 879 is energised, and pressure fluid is fed on line 076 to'the cylinder Alia to cause inward movement of the male die.

When tho male die is fully in, the male die3 in switch Slh closes. While the male die is moving in, a carriage 12 carrying a glass sheet 9 is still moving and operates switch S4 before it comes to rest against tho carriage stop 24,°. Operation of switch SA initiates the inward movement of the female die, so that the lifting f1»i"ers lift :.he hot. ass sheet o from the carriage 12 before tbp onrrJ a^e is brourht to rest nrra5 ust the oarriri r stoo so that i-.he Impact of the carriage against carriage - 120 _ 40265 * stop 1:; not irnn.-ml • lr«l 1o ho!. |*l.ana nhcrt, Wli.li the mail<_> e switch Oh dosed hs the carriage 3 2 approaches the carriage atop 242 the fcnuXe die relay R8 is energised through the closed • 5,. reset rnvitch Sl.f>, Figure 20 on the lifting finder mechanism.which sv/itch is open v/hen the actuating - rod f>|>5 slidablte in the cylinder 550 is in the raised ' position. -The cylinder 550 i3 pneumatically operated throuph a solenoid operated spool valve Q50 having two 10 operating solenoids 951 and 052 and supplied on a line 953 with air under pressure from the line 913, Figure 44, and having an exhaust line 054. The valve is normally in the position such that the actuating rod 555is raised. When contacts S41, Figure 45, of the limit switch 15 S4 close the solenoid 051 of the pneumatic valve 950 is energised to apply air under pressure to the top of the cylinder 550 to force the rod 555 downwardly so that the cam roller 532 is maintained in contact with the cam surface 565 and the switch is closed. The 20 pneumatic valve 950 remains in the condition supplying pressure to the top of the cylinder 550 and effectively acts as a spring forcing the cam roller 532 downwardly on to the cam surface.

By this time the male die has moved in to bending 25 position and the male die in switch S14 is closed so that when the sv/itch S4 is closed as the carriage is conveyed into the tilting box the female die relay R8 is energised and is latchcd in by its holding contacts NP.l. The normally-closed contacts r.P3 open nnd l.y- 30 open contacts PP2 close so that solenoid Pr-1 e 121 40255 die actuating valve 072, Figure 43 is energised and solenoid 073 is de-energised and inward movement of the female die begins. Contacts R84 on tho female die relay R8 also close and start operation of the timer T4 which after a time delay closes contacts T41 which actuate the solenoid 503a of the valve 503; Figure 24, to apply vacuum to the male die in order to assist bending by drawing the hot glass sheet against the male die surface 480.

The contacts T41 close to apply the vacuum at a time when the tending operation is almost complete and the female die is just reaching the end of its inward movement. At a later time after bending and when the female die is being retracted and the tipper edge of the sheet has already been gripped by the tongs, contacts T41 open and contacts T42 of timer T4 close to energise operating solenoid 501a of the pressure valve 501 to supply air under pressure to the male die to assist in releasing the bent glass sheet from the male die surface.

As the female die moves in the lifting fingers pick up the hot glass sheet from the carriage and the sheet is engaged by the female die sections as they move through the rollers 8 in the tilting box. The hot sheet is then carried fowardly from the rollers 8 towards the male die. The female dies partly in switch Sll closes which switch is in series with the normally closed female die out switch S12 and with the coil of the rollers vertical relay R9 which is energised and closes holding contacts R91 to latch the relay through normally-closed - 122 - 40255 malo dio part out switch 813. The normally closed contacts R93 open and the normally-open contacts R92 close so that solenoid 883 of valve 882, Figure 43, is .' ' Js-. ■ >■ de-energised and solenoid 884 is energised and the cylinder 301 "i3 operated to tilt the frame to its . * « » v . * * horizontal position which brings the rollers 8 in the tilting box vertical. It is during this tilting movement of the tilting box that the inward movement of the femalo die is completed to complete the bending of the glass between the dies, the bent glass is then being held on the lifting fingers between the closed dies.

Vhen the female die is fully in, the female die in switch SIO closes, Figure 46. This switch SIO is in series with the rollers vertical switch S8, the hoist raised switches Sl6, which are closed in the condition in which the hoist frames 581 are raised, and with the coil of the tong bar relay RIO. In parallel with the female die in switch SIO and the rollers vertical switch S8 is holding contact R101 of the relay RIO, and a normally closed contact Rill of a hoist raised relay Rll, Figure 47 is in parallel with the hoist raised switches S16. When the female die In switch SIO closes the relay RIO is actuated, contacts R102 open and contacts R103 close, the valves 887 and 892, Figure 43, supply pressure fluid to the cylinder 575a and 575b and lowering of the hoist frames 581 begins, Figure 30, to begin the lowering of the tong bar 23 towards the upper edge of the bent glass sheet held between the dies. _ 123_ 40255 While l-ijo tone bar 23 is raised contacts S211 and S?l? on tone *>ar raised switch S21 are cloned and solenoid 914 of the pneumatic spool valve 911» Figure 44, is energised to supply pressure air to the tops of the cylinders 664jFi«ure 30, to be depressed so that the tong jaws open. As the tong bar is lowered the open tong jaws becomes positioned exactly above the upper edge of the glass sheet which is held between the bending dies the tong jaws having moved downwardly into the recesses formed in the upper edge of the male die and between the sections of the female die.

When the tong bar is lowered switch contacts S221 and S222 on a switch S22 close and the solenoid 915 of valve 911 is energised to cause the valve to change over so that the pusher rods 662 are retracted and the tong jaws close under the weight of their sliders, onto the upper edge of the glass sheet. i When the pusher rods 662 are retracted the two switches S19 close to actuate a timer T5 v/hlch is set to the shortest possible time delay, up to 5 seconds, to allow tho tong points to grip into the upper edge of the glass sheet so that the sheet is securely suspended from the tongs when the dies open. Contacts T51 of the timer T5 then close to energise solenoid 952 of the » pncumatic valve 950, Figure 29, so that the actuating rod 550 is retracted to lift the cam roller 532 from the cam surface and to drop the lifting fingers. The striker plate 556 engages tho switch S15 to open its normally-closed contacts and the female die - 124 - 4UKaa r<*l;iy RO !•; dr-pncrg.i :•»'(! • Tlio contact:; R02 open nnd the contacts 1103 clor.o, solenoid 074 of ; valve 072 lu do-energised and solenoid 073 Is energised and retraction of tho female die begins. 5 The time of closure of the dies to bend the glass sheet may be for example 8 seconds.

When the female die is partly out the female dic3 partly out switch S9 opens to de-energise the male die relay R7 so that contacts R72 open and contacts 10 R73 close, solenoid 870 of valve 877 is energised and solenoid 879 is de-energised and retraction of the male die begins.

When the female die is fully out the female die out switch S12 opens, and at this time the male die 15 is partly out and the male die partly out switch S13 opens and when both switches have been opened the rollers vertical relay R9 is de-energiscd, contacts R92 open and contacts R93 close, and tlio solenoid 884 of valve 882 is de-energised and the solenoid 20 883 is energised so that pressure fluid is supplied to the bottom of the cylinder 301 to tilt the rocking frame back to its inclined position with the upright rollers 8 in the tilting box at their preset angle, e.g. 5°» to the vertical, ready for receiving the 25 next glass sheet from the furnace. The retraction of the male die continues until it is fully out*. The bent glass sheet is left freely suspended in the tongs between the open bending dies ready for lowering through the boost heat section and the pre-cooling 30 section into the chilling liquid. - 125 - 40258 When tho rocking froma is tilted to its inclined position the rollers tilted switch S7, Figure 47, closcc. This switch S7 is in series with closed contacts R104 oi the -.tong bar rolay RIO, normally closed contacts PE1 of a photo electrically operated switch which is operated by the plates 668 on the hoist as will be described, normally closed contacts R112 of the hoist raise relay PHI, and with the coil of a hoist lower relay R12 and with a hoist lower timer T6. The relay coil R12 and the timer T6 are connected in parallel.

Holding contacts R122 of the hoist lower relay R12 close to latch the relay. Contacts R123 close to energise a solenoid 955 which lowers the exit stop 242 to permit the carriage 12 to be conveyed out of the tilting box.

The hoist lower timer T6 Immediately closes contacts T6l to energise the sclsnoid 906 of the valve 904 controlling supply of pressure fluid to the hoist motor 616. At the same time contacts R124 of the hoist lower relay R12 are closed to energise the solenoid 940 of valve 939, Figure 44 to supply pressure air through the valve 937 to tho cylinder 927 so that the piston 930 is extended and tho lever arm 926 of valve 909 moves from position A corresponding to zoro speed of the motor 616 to position B which determines a first speed of the hoist motor 616. At this time the drums of the hoists aro held stationary by engagement of the - 126- 40235 disc brake, tlio ulippin/; clutch of each drum permitting this although l.lio motor in being driven.

After a set time delay, for example 2 seconds, tho contacts. TG2 of the hoist lower timer T6 close to energise the brake release solenoid 921 of the valve 920 in the brake operating circuit, to take high pressure off-the brake caliper arms and at the same time energises the lower pressure solenoid 924 of the valve 923 through contacts R125 of the hoist lower relay R12. After a further time delay, lip to 20 seconds, the contacts T63 of the timer T6 close to energise the solenoid 944 of the pneumatic valve 943 which switches pressure air through the flow control valve 941 to the inner end of the cylinder 928 causing that cylinder to move in the housing 929, towards the right as shown in Figure 44, and cause movement of the lever arm to position C to determine a second faster speed of the hoist motor 616.

This acceleration of the hoist motor 616 to a second speed takes place at the appropriate time when it is required to accelerate part of the glass sheet through the boost heat section to achieve a temperature gradient in the glass as described with reference to Figure 39. The acceleration takes place for example when the lower edge of the glass sheet has just passed through the boost heater panels.

The plates 660 on the tong bar 23 now cut off light beams to photoelectric cells not shown, which ure connected to switching circuits which open the contacts PE1 to de-energise the hoist lower relay R12 - 127 _ 40255 and tlio hoist lower timer T6 which instantaneously releases switches R124 and T63 to de-cnergise the solenoids 940 nnd 944, thereby refracting tho double cylinder system 927, 928 and causing the lever arm 926 of valve 909 to return to position A so that the speed of tho hoist motor returns to zero.

; After a delay to permit deceleration of the hoist system tho switch T62 opens and the brake release solenoid 921 is de-energised, this operates in the brake circuit to put the high pressure back on to the brake caliper arms to brake the hoist motor when the lower edge of the glass sheet is just reaching the shoes 807, Figure 40, in which the glass rests. The contacts T6l open after a delay to de-energise the hoist lower solenoid 906, the motor 616 then being stationary.

When the glass is being heated in the furnace prior to entry into the tilting box for bending, a push button switch S24 is closcd, and operates solenoid 902, Figure 43, of the valve 901 operating the scissors lift table, through normally-closed contacts S201 of switch S20, Figure 42, to supply pressure to the bottom of cylinder 849 to raise the table 30 carrying the quench tank 26 to the raised position ready to receive the hot bent glass. When the tank 26 reaches its raised position the contacts S201 of switch S20 open * and the valve 901 maintains pressure on the cylinder to maintain the tank 26 in its raised position.

A few scconds after the hoist motor 616 has stopped and the (jloss is quenched in the tank, a push button switch S25 is operated to energise solenoid 903 _ 128 _ 40255 of volvc 901 through closed contacts S202 of the switch S20, which switches pressure fluid to the top of cylinder 849 to lower the scissors lift tabic which leaves the quenched glass 856 in the rack 807, 808 as. the qucnch tank 26 moves downwardly. The contacts 202 open when the tank reaches its lowermost position and de-energises the solenoid 903.

The glass is now supported in the rack 807, 808 and is still gripped by the tongs. To open the tongs a tong release push button switch S26 is operated to energise a solenoid 957 which causes pusher members, not shown, in the pit, to engage the striker plates 655 on the arms 654 to tension the cables 661 and open all the tongs. The glass sheet then settles on to the rack, the tong points then being just clear of the tipper edge of the sheet and the tongs can close again prior to being lifted by the hoist.

A further push button switch S27 is then pressed and energises through closed contacts R105 of the tong bar relay RIO the hoist raise relay Rll and the hoist raise timer T7.

The relay Rll is latched by its holding contacts R113 and instantaneously the timer T7 closes contacts T71 to energise the solenoid 905 of valve 904, and solenoid 958 of the by pass valve 910 in the hoist motor supply circuit.

At the same time contacts R114 of the hoist raise relay Rll close to energise a solenoid 959 which raises the carriage stop 242. The contacts - 129 - 40255 H115 and K116 dose to energise, through normally- » dosed contacts T7jJ of timer T7, the speed control solenoids 940 and 944 so that the lever arm 932 is moved to position C and the hoist motor 616 is acceleratcd up to top speed determined by fluid flow through the fully open valve 909 and the open by-pass valve 910 in parallel.

The tong bar is thus returned quickly before the next glass sheet moves between the dies and when near the top of i'ts upward travel the contacts T73 of tho hoist raise timer T7 open to de-energise the speed control solenoids 940 and 944.. The motor 6l6 decelerates to a creep speed determined by the by-pass valve 910 and continues to raise the tong bar at creep speed.

The hoist raise timer T7 has further contacts T72 which close after a delay to energise the brake release solenoid 921 which causes the valve 920 to remove the high pressure from the brake calipers and at the same time through closed contacts R127 energises the zero pressure solenoid 925 of the brake circuit. The brake is right off the hoist motor 616 at this stage.

The normally closed contacts Rill of the hoist raise relay Rll open when that relay is energised and when the hoist raised switches Sl6 are all open the tong bar relay RIO is de-energised, switch R102 closes and switch R103 opens to raise the hoist frames 501 by actuation of the valves 887 and 892 to raise the pistons in the cylinders 575. Contacts _ 13a. 40255 R105 uloo open to de-energise tho hoist raise relay Rll and tho hoist raise timer T7. After a time delay to permit the motor 616 to wind up any slack and to ensure that tho wires have all been 5 raised together and to make sure that there is Just enough tension on the slipping clutch on each drum to make sure that the wires are up together, the switch T71 opens to de-energise the solenoids 905 and 958 of the valves in the motor circuit, so that 10 the hoist motor 616 is brought to rest. At the same time the contacts T72 open to put full pressure back onto the brake caliper arms.

When the tong bar is fully raised the switches S211 and S212 close to energise solenoid 914 and 15 open the tongs.

Tho processing sequence then restarts for the next sheet to be bent and toughened.

For the manufacture of an annealed sheet and a toughened sheet in succession when those sheets are to 20 be laminated together to produce a laminated windscreen, a modification of the apparatus may be employed as illustrated in Figures 48 to 50.

The main criterion is that the overall deformation index of the annealed sheet should not be greater 25 than the deformation index of the toughened sheet. Usually matching values of deformation index are achieved but satisfactory production is also achieved with the annealed sheet having a deformation index less than that of the toughened sheet. Up to the time at 30 which the bonding dies open both sheets have identical - 131 - 40295 t thermal histories and tho bent shapes of the sheets which at th»t stage match for Inclination are preserved during subsequent thermal processing.

In Figure AO the pit below the rocking frame 20 for the tilting box is illustrated. The boost heaters of Figure 39 are indicated at 27 and the location of the two blowing boxes 28 is also indicated.

Two baskets are provided for receiving the hot bent glass sheet as it is lowered and in Figure 48 a basket 970 for receiving a bent glass sheet which is to be annealed is shown in position beneath the blowing boxes 28. Tho basket 970 has a girder framework 971 the sides and bottom of which arc covered by expanded metal mesh 972, and the basket is mounted on a wheeled carriage 973.

The carriage 973 is in the form of a rectangular frame of U-section girders. Flanges 974 extend rearwardly from the rear corners of the carriage and carry stub shafts 975 each of which extends between a pair of flanges 974 as illustrated in Figure 49. On each stub shaft 975 there i3 carried a wheel 976 which wheels 976 man on the upper faces of a lower pair of parallel girders 977 which extend across the pit from a position beneath the boost heaters 27 and the blowing boxes 28 to a glass elevator 978 which is mounted at one end of the pit. t A cross girder 979 forming part of the carriage 973 carries stub shafts 980 at either end on which are mounU.-d whorl:; 981 which run on horizontal flange:; of an uppor pair of girili-rs 9 As shown in detail in Figure 50 a shaft 984 extends between the ends of the girders 977 adjacent the glass elevator 978. The shaft 984 is mounted in bearing blocks 985 carried by the girders 977 and a sprocket wheel 986 is mounted on each end of the shaft 984. The shaft 984 is driven by an electric motor 987* A similar shaft 988 with two sprocket wheels 989 is mounted between the innermost ends of the girders 977 beneath the blowing boxes 28. Drive chains 990 extend between the sprocket wheels 986 and 989 and lugs 991 on the flanges 974 at the rear of the carriage 973 connect with the drive chains 990.

When the bent glass sheet is to be annealed the basket 970 is positioned below the boost heaters 27 and the blowing boxes 28 and the bent hot glass sheet is lowered into the- basket 970 and comes to rest on spring loaded supports 992 in the basket. Additional spring loaded supports 993 engage the sheet near its top edge to steady the sheet in the basket. The tongs are then released and the electric motor 987 is operated to move the carriage and withdraw the basket 970 to the outer end of the track way formed by the girders 977 and 983 adjacent the glass elevator 978 which has lifting hooks 994 which are lowered into the basket to pick up the glass by its lower edge from the basket 970 and to raise the glass to floor level at which the glass can bo removed manually from the elevator 978. Throughout - 133 - 40295 ita movement across the pit and in the elevator the glass is cooling to an annealed condition. V/hen tho basket 970 for receiving a glass sheot to be annealed has been withdrawn from beneath the blowing boxes 28 5 o second basket 995 is moved into position beneath the blowing boxes 20 for receiving a hot bent glass sheet which in to bo quenched.

Tho basket 995 is of similar construction to the backet 970 being formed by a girder framework 996 10 the sides and bottom of which are covered by expanded metal mesh 997. The basket 995 is shaped so that It can become immersed in the chilling liquid in the qucnch tank 26 when the tank is raised for receiving the bent glass sheet to be quenched. The basket 995 is suspended 15 from a wheeled carriage 998 whose wheels 999 run on a pair of parallel girders 1000 which extend from a location just below the blowing boxes 20 parallel to and in opposite direction to the track way formed by the girders 977 and 903 to the other end of the pit where there is a second 20 glass elevator 1001. A chain drive system similar to that for moving the carriage 973 which supports the basket 970 is employed for moving the carriage 998 from which the basket 995 is suspended butthis drive system is omitted for clarity. 25 When the basket 995 is in position just beneath the blowing boxes 28 the quench tank 26 is raised by the scissors lift table 30 so that the top of the quench tank .is just below the blowing boxes as already described and the baiikot 995 is completely immersed. 30 The next hot bent glass sheet in the succession - 134 - 40255 )' - oi' .'shoots is lowered through the boost heaters 27 and the blowin:. Nixon 28 into tho chilling liquid in the * quench tank nml the glar.s becomes supported on spring , I loaded support.:; 992 and yY)5 in tho banket 995 which arc similar to tlior.o already described in tho basket 970. When tho quenched glass sheet is so supported the tongs are released.' The quench tank 26 is lowered away from the basket 995 which is moved on its carriage 998 along the pit to a position adjacent the glass elevator 1001 which has lifting hooks 1002 which are lowered into the basket 995 to pick up the toughened glass sheet. The lifting hooks 1Q02 are raised lifting the sheet from tho banket 995 which is then moved forwardly along the; girders by a short distance to clear the glass for lowering into a degreasing tank 1003 mounted on the floor of tho pit.

The elevator 1001 raises the degreased glass from tho tank 1003 to floor level for manual removal from the lifting hooks 1002.

Y/hile these operations are being carried out on tho quenched glass sheet, the basket 970 for receiving the next glass sheet for annealing is moved into jjosition below I he Wowing boxes PO. 'i'ho boo:: t heaters 27 and Lite blowing boxes 20 of the pre-cooling section remain operative throughout the production of the succession of alternately annealed and toughened bent glass sheets." I'reserva I. i on of tho match in;: shapes of the sheets is important end it is considered that matching shapes nrr 1 :iser\'«-.! if step.-, are taken to ensure that the - 135 - 40255 overall deformation index readied by an annealed glass shcot is less than or at mo3t equal to that of a toughened sheet.

Up to the time at which tho bending dies open 5 every sheet in the succession has an identical thermal history and will have reached the same deformation index. The bent shapes of the sheets match for lamination and these matching bent shapes must be preserved during subsequent processing. 10 For example when bending sheets of glass 2.2 mm thick which are to be used as laminates for automobile windscreens, with a bending temperature of 603°C for example the deformation index reached by every sheet is about 2 x 10"11 at the time when the bending dies 15 open. Ihis value is small compared with the further increase in the deformation index which occurs during the passage of the shtcts between the boost heaters 27 and tho blowing boxes 28.

There is an increment in the deformation index 20 of each sheet as it passes from the bending dies to the boost heaters but this is very small and can effectively be ignored. Therefore it is the increment of the deformation index of the sheets as they pass between the boost heaters 27 and the blowing boxes 28 which is significant 25 and has to be taken into consideration. For matching of the overall deformation index of the annealed and the quenched sheets it is therefore arranged that the increment in the deformation index of a sheet to he annealed when that shoot is pairing through the boost 30 heaters 27 and the blowing boxes 28, is less than tho _ 136 - 40255 Inert (::■ lit. ill l.lie di.Tuiiiuil iun Index of u t;heel- whicli i:: to he i|iieiii:|niii11. i i|iial l.o l.|i«• fnrl.hor Jiici'i'inciiI. jii the rioJ'ortual..ion index of on annealed shoot which v/ill occur during the final slow cooling of the 5 annealed sheet.. This is illustrated in Table XIII which compares the temporat.ure/timo histories of a toughened and an annealed sheet which are both of soda-lime-sllica glass 2.2 mm thick for use as laminates in the manufacture of on automobile wind-10 screen. The glass bending temperature was C0'j°C and the temperature of the boost heaters was 9D0°C. " 117 " TABLE XIII Toughened Sheet Annealed Sheet 1 •Annealed Sheet 2 Boost Heat Tirr.s 4.3 sec. 3.9 sec. 3.44 sec.

Glass tenperature on leaving boost heaters 642°C 639°C 635°C | Tir.e between boost h waters and pre-coolir.g 0.5 sec. 0.45 sec. j 0.4 sec.

Class temperature on entering pre-cooling 640°C 637°C 637°C rrt—coolir.g tine 0.5 sec. 0.45 sec. 0.4 sec. i Averace temperature through glass thickness after pre-cooling 624°C 622°C i 620°C ! i | Time between pre-cooling and quench 0.1 sec.

- Deformation Index Increment - boost heat to instant of quench - boost heat and pre-cool - final 3low cooling after pre-cool 4.6 x 10-10 3.45 x 10~10 1.13 x 10~10 1 2.45 x 10~10 0.97 x 10"13 i This Tabic shows that the total increment in the defonnation index of the sheet being annealed from the point of entry of the sheet between the boost heaters 27 until the sheet has .been finally cooled to a temperature corresponding to the strain point of the glass is 3.45 x 10~10 + 1.13 x 10~10 - 4.58 x 10~10.

Within the limits of operational error this value is equal to the increment in the deformation index of the sheet being toughened from the point of entry of that chcet between the boost heaters 27 until the instant of quenching upon entry of the sheet into the chilling —10 liquid, which increment is 4.6 x 10 Equalisation of the values of deformation index for a toughened sheet and an annealed sheet in this way, which sheets are produced in succession, ensures retention of their matching shapes.

The overall defonnation index of a toughened and an annealed sheet is similarly matched when the sheets are processed so as to have a top to bottom temperature gradient, by taking into consideration the deformation index reached by the top edge of each sheet. This ensures physical matching of the top edges of the sheets which is the4 most critical region in the lamination process.

As already stated it is found that tho matching shapes of the toughened and annealed sheets are retained so lonj^ as the annealed sheet is brought to an overall floforntaI i on index not greater than that of the toughened sheet a>ul the third column of Table XIII illustrates the production of an annealed sheet having a total increment - 139 - in deformation index from the point of entry of the sheet between the boost heuters 27 until finally annealed which is 3.42 x 10~10. This is less than the increment in the deformation index of 4.6 x 10"*^® for the toughened sheet'given in the first column of Table XIII and the annealed sheet having the lower increment of deformation index retained its shape matching a toughened sheet and -successively produced toughened and annealed sheets matched accurately in the subsequent lamination process.

An alternative embodiment of the lifting fingers of Figure 25 to 27 for attachment to the bottom corners of the female die 15 is illustrated in Figures 51 to 53.

In this alternative embodiment each of the lifting fingers is of cylindrical form consisting of a cylindrical sleeve of a refractory material, for example a ceramic such as boron nitride, which sleeve is illustrated at 1570 and is mounted on a rod 1571 so as to be freely rotatable on that rod being held in position by a circlip 1572.

The rod 1571 is fixed in an L-shaped arm 1573 which is pivotally mounted on a horizontal spindle 1574 which is fixed in a pivot block 1575 which is itself fixed to the bracket 512 attached to the back frame 431 of the female die.

The lower end of the L-shaped arm 1573 carries a pivot pin 1576 to which is connected a fork 1577 on the end of a rod 1578 whose other end carries a fork 1579 which is connected to a pivot 1580 carried at the lower end of a lever arm 1581 whose upper end extends through a clot 1502 in a bearing block 1583 which is mounted on tho rear end 1584 of the bracket 512 which is fixed to the back frame 431 of the female die. _ 14o _ 40855 Tlio- beuring block 1503 ±3 fitted with a laterally extend i.rw; tube 1505 in which thero 13 mounted a shaft 1586 to which the upper end of the lever arm 1581 is fixed by a dowel pin 1587. The shaft 1586 rotates in bearings 1588 fixed into tho bearing block 1583 and in a bearing 1589 in the end of the tube 1585 away from the bearing block 1583- Tlio upwardly extending crank arm' 521 is fixed to the free end of the shaft 1586 which extends out of the tube 1585 beyond the bearings 1589. As already described the crank arm 521 has an upwardly extending spike 522 over which fits the ring member 523 on the actuating aim 524 in the sane way as illustrated in Figure 25.

Movement of the actuating rod 524 by the mechanism illustrator! in Figures 28 and 29 rocks the crank arm 521 and causes the L-r,hoped arm 1573 to pivot about its horizontal spindle 1574 to raise the cylindrical lifting finger from its downwardly depressed position by an amount sufficient to cause the ceramic sleeve 1570 to engage the lower edge of tho glass sheet and to lift the sheet from the carriage.

Because the cylindrical sleeve 1570 is rotatable on the rod 1571 any tendency of the hot glass sheet to move sideways as it is being lifted and bent, is accommodated. Tho lifting finger at each bottom corner of the backing frame 431 of the female die is constructed ns illustrated in Figures 51 ami 53 aiid a .similarly constructed and operated lifting finger of cylindrical form may be provided centrally of the lov;or edge of the fomule die. Alternatively a ccntrally .located lifting finder of - 141 - 4U4DO I cyl tndrlcal form may bt: provided on the fmalc die . actuated by a mechanism similar to that ju3t described j or operated directly by an hydraulic cylinder.

Patent Specification No. 39606 claims a method of 5 heating a glass sheet to a thermal condition for further processing comprising seating the lower edge of the glass sheet on lower edge supporting means with the sheet in an | upright disposition, leaning tho sheet against upwardly • projecting mechanical supporting means which provides { 10 transient support for the sheet and defines a horizontally j disposed path through a heating zone, the sheet leaning at j ! a near-vertical angle, driving the lower edge supporting means and the upwardly projecting mechanical supporting means , j to advance the sheet through the heating zone, controlling j i 15 the heat transfer to the glass sheet during its advance through the heating zone, and, as the sheet is heated to said thermal condition and relaxes against said upwardly projecting mechanical supporting means, timing the advance of the supported glass sheet through the heating zone to 20 limit deformation of the sheet to an amount less than the maximum deformation which is acceptable in the processed glass sheet.

Patent Specification No. 39806 further claims apparatus for heating glass sheets, for example for bending and/or 25 toughening, comprising a heating furnace through which glass sheets are to be conveyed in upright disposition, a conveyor for the sheets extending through the furnace and including a movable support for the lower edge of a sheet and a plurality of spaced—apart near-vertical rollers 30 defining an inclined support extending through the furnace against which a sheet can lean as it is heated, and driving means lor advancing tho movable support through the furnace - 142 - 40255 and for driving said near-vertical rollers at a linear surface speed the same as that of the movable support.

Patent Specification No. 39806 claims a method of shaping and toughening a glass sheet comprising heating a glass sheet to a predetermined temperature condition in which it can be shaped, closing glass-shaping surfaces on the sheet, which surfaces are maintained in the same temperature condition as the glass sheet, retracting those surfaces from the sheet, and subsequently heating the glass sheet to a pre-quenching thermal condition before toughening the sheet by contacting its surface with a chilling medium. - 143 -

Claims (9)

1.CLAIMS: 1. A method of shaping a hot glass sheet comprising supporting a sheet of glass on its lower edge, providing near-vertical support for one face of the sheet so that the sheet is disposed at a small angle to the vertical, advancing the sheet while so supported through a heating furnace to a shaping station, closing shaping dies on to the sheet at the shaping station and tilting the dies through an angle to bring the sheet to a vertical position, then opening the dies and removing the shaped sheet for subsequent thermal treatment.

2. A method according to claim 1, for producing a bent sheet of glass, comprising closing bending dies on to the hot sheet at the shaping station, tilting the bending dies through an angle to bring the sheet to a vertical position, and then opening the bending dies and removing the bent sheet vertically for subsequent thermal treatment.

3. A method according to Claim 2, comprising closing said bending dies by moving a male die having a convex surface into bending position, supporting the hot glass sheet against the female die which carries the sheet against the male die to bend the sheet, gripping the upper edge of the bent sheet when it is vertically disposed, opening the dies so that the bent sheet is suspended, and then removing the suspended bent sheet vertically for subsequent thermal processing. - 144 - 40255 'i.

4.A method according to Claim 2 or Claim 3» \ compri sing initiating tilting of the dies when the hot glass sheet first contacts the male die.

5.A method according to, any one of Claims 2 to 4, 5 in which 1.ho sheet of glass to be bent is advanced along a horizontally disposed path through the heating furnace to the bending station, comprising providing transient support for the sheet at the bending station by leaning the glass against spaced-apart near-vertical lo support rollers, initially driving those rollers at a rate such that their linear surface speed is the same as tho speed of advance of the glass into the bending station and then slowing the rotation of those rollers as tho advru :-. o of a hot glass sheet into the bending station is slowed between the bending dies, moving female bending die sections through said support rollers to dis-engage the sheet from the rollers and simultaneously picking up the lower edge of the sheet so that the female die carries tho sheet against the male diq. 2o

6. A method according to any one of Claims 2 to 5» comprising providing transient support for the glass sheet during its travel through the furnace by leaning tit sheet at a near-vertical angle against spaced-apart, near-vertical support rollers, driving those rollers at 25 n rate such that their linear surface speed is the same as the speed of advance of the glass sheet transiently supported by the rollers, and setting thermal conditions in the furnace and setting the time tin* sheet, is within t.h- furnncf- in dep« nee on Hie gins:*. 'hickn; r.L :iO as 145 - 40255 to achieve a predetermined temperature condition in I the glaus prior to bonding, the thermal and time nettings being such as to permit the supported glass lo relax on it ic heated by an amount .less than the 5 maximum flrformafcton of the .-.licet which In acceptable prior to bonding.

7. A method according to any one of Claims "2 to 6, wherein tho bending dies are heated to a temperature condition matching that of a glass sheet to be bent lo presented between the dies. O. A method according to Claim 7, wherein the bending dioa are heated to a surface temperature distribution such that nt all points of contact with a glass sheet presented between tho dies the surface temperature of 15 the dies is substantially equal to that of the glass. 9. A method according to Claim 7, comprising heating the glass sheet to have a predetermined uniform surface temperature, or substantially so, prior to bending, and maintaining the surface temperature of the bending dies 20 at that predetermined temperature, or substantially so. 10. A method according to Claim 9, comprising enclosing the bending dies and maintaining the enclosures at said predetermined temperature. 11. A method according to any one of Claims P. to 10, 25 comprir.irig annealing the bent sheet after removal from the bending dies. 1?. A method according to any one of Claims 2 to 10, comprising removing the bent sheet for quenching to toughen the sheet. - 146 - 40285 l/>. A iik'DioiI .H .'.ii'il 1 ug lo CI.) im 1.'', minpri:: i11|» 1 ougheniug Uio :.|i«m>I. liy contactIng llu- sheet with n chill iiig liquid. 14. A method accordIng to Claim 13, comprising toughening the sheet by lowering it into a body of ^hilling liquid. 15. A-method according to Claim 14, wherein the sheet is subjected to cooling gas streams flowing uniformly over both faces of the sheet, just before the sheet enters the chilling liquid to produce centre-to-surface temperature gradients through the thickness of the sheet without substantially cooling the central core of the sheet thickness. 16. A method according to Claim 14, comprising determining the location of the surface of the chilling liquid relative to sources of the cooling gas flows by maintaining a constant level of the chilling liquid, and locating that level at a predetermined distance below said cooling gas flow sources. 17- A method according to any one of Claims 2 to 16, for producing a succession of bent glass sheets, wherein after lowering of a bent glass sheet has begun the dies, as they arc opening, are tilted back to an inclined disposition to roccive between Uu-ra the next ncar-vcrtical sheet for bend in*;. 1M. A method according to any one of Claimr. P. to 16, for producing a watching pair of curved glass sheets; for subsequent lannrnllon together t.o produce a laminated window unit, con?vising passing each sheet through the heativg furnace to a bending station, heating c-ach sheet - 147 - 40255 lo the same thermal oend i.1..i on during 1 ts.- advance through the hcitlng furnace, bending each sheet to the same desired curvature betv.'-.-..n said bending dies, maintaining constant condition:; while both sheet:; arc heated and bent, and 5 subsequent to bending rapidly chilling one of the sheets to induce predetermined toughening stresses therein and annealing the 6ther cheet. 19. A method according to Claim 17, for producing a succession of matching pairs of bent glass sheets, com- lo prising advancing glass sheets in succession through the heating station, bending the sheets in succession, alternately toughening and annealing the bent sheets as they are removed from the bending station, and selecting for subsequent lamination a toughened sheet and an annealed sheet suc-15 cessively produced. 20. Apparatus fox shaping a dot glass sheet, ^onorisine » tiltinr enclosure containing means for supporting a hot glass sheet at a near-vertical angle, which enclosure is formed with access means permitting a hot glass sheet to be received 2o on the support means at said angle nnd to be removed vertically from the enclosure, means for tilting the enclosure between a position in which a glass sheet at said angle is received on tho support means and a position in which the glass sheet is disposed for removal vertically 25 from the enclosure, co-opor;»ti.ng rjass-orir^ing dies mounted in tho enclosure one of which dies is constructt*d to advance from boh'« ml arid through si id support in-oiir: as the dies close on in t^lass sheet., and means for engaging the rlas.~ .si.net it is between the closed rtid.-i and for re- 3o movin/: the sheet vertically frcm the enclosure when the dies open. 148" Apprirntu;- i:ig to i.'laito ?0, comprising a heating furnace through which glass sheets are to be conveyed in upright disposition, a conveyor for the sheets extending through the furnace and including a moveable support for the lower edge of the sheet and a plurali ty of spaced-apart near-verti cal rollers defining mi inclined support against which a sheet can relax an it is heated, the tilting enclosure being mounted adjacent the end of the furnace and having an entrance in an end wall contiguous to the furnace and an exit mouth positioned for removal of a sheet vertically from the enclosure a plurality of spaced-apart near-vertical rollers in the enclosure defining when the enclosure is tilted an inclined support for a hot glass sheet r.o-f.xtensive with that provided by tho furnace rollers and against which a hot glass sheet can lean when it is brought to rest between the bonding dies, co-operating glass-engaging dies mounted in the enclosure one of which dies is constructed to advance from behind arid through mid rollers, menus for tilting 1.1 ir: enclosure between it:; Lilted position and a position in which the glass sheet between tho dies, when closed, is vortical, means for engaging the glass sheet when between the dies and removing the sheet vertically through the exit mouth v/hen the dies open, and thermal treatment means moynted vertically in line with the exit mouth for thermally treating the gliurs sheet. •10 2 5 5 22. Apparatus according to Claim 21, wherein the tilting enclosure is a tilting box having an entrance in an end wall and an exit mouth in the floor for removal of a sheet vertically from the box, and the glass-engaging dies are co-operating male and female bending dies mounted in the box one of which dies is constructed to pass from behind and through said near-vertical rollers as the dies close on to the glass sheet. 23. Apparatus according to Claim 22, including means for heating the interior of the box, and sequence control means connected to actuating means for the dies, the means for tilting the box and the glass engaging means to control them according to a predetermined sequence for bending and levering the glass sheet for subsequent thermal treatment. 24. Apparatus according to Claim 22 or Claim 23, wherein the tiling means comprises a pivoted frame - 150 - 40285 1 i on which the box i3 mounted, and actuating means connected to tho frame and operable to pivot the frame between a i tilted position and a horizontal position. 2 5. Apparatus according to Claim 24, comprising male 5 and female die actuating means supported on said pivoted frame, and each die includes a backing frame which is connccted to the actuating means for that die. 2 6. Apparatus according to Claim 23, wherein the means for heating tho interior of the box comprises gas com-lo bustion apparatus supported by the pivoted frame and communicating with the box to direct hot gas into the box, and temperature control means responsive to a temperature within the box to regulate the gas combustion apparatus so as to maintain the bending dies at the same temperature 15 as that of a hot glass sheet entering the box. 2*. Appnratu:; according to any one of Claims 2 2 to 26, comprising bottom rollers which project through the spaces between the near-vertical rollers and at an acute angle thereto to define a track for a moveable carriage on 20 which the lower edge of a glass sheet is supported as it is advanced into the tilting box through an entrance slot which is formed in one end wall of the box in alignment with the near-vertical rollers. 2

8. Apparatus according to Claim 2 5, wherein the female 25 bend in,r: die is a ring frame die shaped to co-operate with the male die and made up of die sections shaped to pass from behind nnd through said near-vertical rollers to d»f.enj^irjc '-he hot glass sheet from said rollers. 151 - 40235 2

9. Apparatus; according to Claim 2®, wherein the female die see'.ions are mounted on the backing frame whjcv> is connected to -the female die actuating means. 3Q Apparatus according to Claim 25, wherein the male 5 die has a continous bending surface for engagement by a hot glass sheet to be bent, said bending surface is perforated and i3 backcd by a chamber which is selectively r connectable to a vacuum line and an air pressure line through valves operable to cause suction or pressure 10 build up between a glass sheet and said perforated bending surface. 31 Apparatus according to Claim 30, wherein the continuous bending surface and chamber of the male die are 15 mounted on tho backing frame which is connected to the male die actuating means. 32. Apparatus according t? Claim 28 or Claim 29, including forwardly projecting lifting fingers motmted at the bottom of the female die, which fingers are arranged 2o normally to pass beneath the supported lower edge of a hot glass sheet as the female die sections pass from behind through the upright rollers, and an actuating mechanism for the lifting fingers operable to raise the lifting fingers sufficiently to lift the glass sheet and 25 provide support for the sheet as it is carried by the * female die towards the male die. 31 Apparatus according to Claim 32, wherein the lifting finders are pivoted on horizontal spindles fixed to the bo Mom outer sections of the female die, cach of the 30 finders is operated by a crank mechanism, and operating mean:; for the crank mechanism is connected to tho female - 152 - 402SS • lie nr. tun Li it/? iiic.-in:i ;uk1 its operrtMi- to rotnle the crunk taech.'inir.m uo t.lie Tcmnlc <1 i«• Js advanced, thereby raiuing the lining ftutors as th'.y pass beneath tho lower edge of th" hot pin;::; sheet. 5 34. Apparatus according to Claim 33, wherein the crank mechanism for each lifting finger includes an upstanding member whose upper end is engaged by an actuating rod whi' h extends backwardly through the rear wall of the tilting box and .Is connected to a lever pivotably mounted on the female lo die actuating means and carrying a cam follower which is resiliently held against a fixed cam plate, whereby move-men I of the lever with said female die actuating means relative to the fixed cam plate causes rotation of the lifting finger crank mechanism. lr> 35. Apparatus according to any one of Claims 32 to 34 , wherein each lifting finger has a flat surface for engagement beneath the lower edge of a hot glass sheet. 36. Apparatus according to Claim 35, wherein each lifting finger is of spatulate form. 2o 37. Apparatus according to any one of Claims 32 to 34, wherein each lifting finger is of cylindrical form 3H. App.'iratun according to Claim 32- or Claim 33 , wherein each lifting finger consists of a cylindrical sleeve of refractory material which is rotatably mounted on a 25 rod ono end of which is pivoted on one of said horizontal spindles. 39. Apparatus according to Claim 38, wherein the sleeve is of boron nitride. - 153 - 40255 40. Apparatu.v; according to Claim 2% including for supporting each die actuating means in tho tilting box, tv/o parallel main support beams located on the pivoted frame in the direction of movement of the 5 dies, which main support beams have upper surfaces / providing tracks on which bearings on the die actuating means run during inward and outward movement of the dies. 41. Apparatus according to Claim 40 , wherein each die actuating means comprises on adjustable die mounting io assembly on its inward end for mounting the associated die. 42. Apparatus according to Claim 4o or Claim 41 , including for each die actuating means an actuating cylinder fixed relative to the main support beams and 15 having a piston connected to the die actuating means, a f^uide roller on tho die actuating means running in a guide tx*ack fixed relative to the main support beams and parallel to the tracks provided by the upper surfaces of those beams, and stop means determining the extent of 20 inward and outv/ard movement of the die actuating means relative to the main support oeams. 43. Apparatus according to Claim 42, wherein each guide track is a central guide channel formed in a U-section guide member which is fixed between the main support beams, » 25 and the guide roller is mounted on a spindle extending downwardly from the die actuating means into said guide chnr.ncl. ~ 154 ~ 40255 44. tus according to Claim 43 , wherein tho inwnrd end of the U-scction guide member is pivotally connected to a base plate which is fixed between the main support beams, the rear end of tho guide member is engaged by adjusters mounted on the main support beams and operable to adjust tho alignment of the guide member angularly about the pivotal connection with the baso plate, and clamping means on the base plate engages tho guide member for clamping the guide member in position relative to the main support beams when it is correctly aligned. 45. Apparatus according to any one of Claims 41 to 44, wherein the backing frame for each die is an open frame of rectangular form, each frame carries at least one upper and a lower horizontal locating bar and the adjustable die mounting assembly includes at least one clamping hook in which said at least one upper locating bar engages to suspend the backing frame from the hook, and a lower clamp assembly engaging the lower locating bar, which lower clamp assembly is adjustable r.t right angles t.o tho lower locating bar to adjust the angle of tho backing frame and of the die carried thereby about an axis defined by said at least one upper locating bar, prior to clamping of tho locating bars in position when the desired angular position of the die is achieved. Ifi . Apparatus according to Claim 45, v/herein that each frame carries two upper horizontal locating bars which are spaced apart symmetrically towards either side of the upper part of each frame, the ad jus Labi e die mounting assembly include:: two clamping hook:-, in which the two upper locating bars engage, and the lower horizontal locating bar ir-carried centrally on the lower part of the frame. I 5 3" 40255 47. Apparnl.ur. according u> (M.-rim 45 or Claim 46, including a rearwardly projecting locating pin fixed to a central strut of the backing frame, which pin is freely engaged in a locating slot formed in a plate 5 fixed to the die support unit which embodies said adjustable die mounting assembly. 48. Apparatus according to any one of Claims 45 to 47 , wherein a rear end plate of the die support unit abuts a front end plate of the associated die actuating lo means, a boss at the centre of one end plate engages in a co-operating central recess in the other end plate, lugs at the side edges of one of said plates are engaged by adjustment means on the other of said plates, adjustment of which adjustment means rotates the die support unit 15 relative to the die actuating means about the axis of the boss, and locking means is provided on said plates for locking the two plates together when adjusted to the desired angular position. 49 . Apparatus according to any one of Claims 22 to 48, 20 wherein the means for engaging the bent glass sheet includes a plurality of tongs suspended from a normally raised long bar in rotatablc gates pivotally mounted on the tong bar, the tongs being spacrd apart along the tong bar-so that when the tong bar is lowered the tong jaws pass 25 downwardly between sections of the female die and into rocesses in the upper edgo of the male die which recesses fane interspaces between tlio female die sections. - 156 " 40255 SO. Apparatus aecord:n;* lo I'lnim 40, ir.e^iuling ton;'. guide means mount ed along tho top oi" both t lio male die ami the female die for engagement by pusher members on the tong gates to rotate the tong gates as the tong r, bar is lowered to cause the open jaws of the tongs to straddle tho upper edgo of the bent glass sheet held between the closed dies. 51 . Apparatus according to Claim 49 of Claim 50, wherein tho ends of the tong bar are attached to lifting cables '«> which are wound around winding means of hoists mounted above the roof of the tilting box, the hoist for each end of the tong bar includes a fixed head frame mounted on a fixed support above the tilting box, a moveable frame mounted on the fixed frame and including guides for the IS lifting cable:; which guides extend through the roof of the tilting box nnd are engaged by the long bar when the lifting cab!or. are wound up on the winding means, and hydraulic moans connecting the moveable frame to the fixed frame and operable to effect upward and downward 2o movement of the moveable frame relative to the fixed frame, the downward movement of which moveable frame lowers the tong bar within the tilting box to a posi tion in which the open tong jaws straddle tlio upper edge of the glass sheet. 2'> 52 . Apparatus according to Claim 51, comprising a centre frame mounted on the moveable frame, and means for adjustment of tho vertical, position of the centre frame relative to the moveable frame, nnd wherein the said guides for the lifting cables are carried by the centre frame. - 157 - 40255 53. Apparatus or.coi-tling to Cloim 52, comprising two lifting coblcs .i L each end of the tong bar respectively attached to thfi front and brick of the tong bar at each end thereof, and wherein said guides include two guide 5 tubes mounted in each of said centre frames, through which guide tubes eh« lifting cables are threaded, the lower ends of the guide tubes are adapted for engagement by the tong bar whon the lifting cables are wound up, and the guide tubes are mounted within the centre frames 10 by means adjustable to determine the extent of projection of the guid e tubes into the tilting box to bring the tong bar and open tongs to a required level dependent on the height of the glass sheet being bent, when the moveable frame Is lowered relative to the fixed frame. 15 54. Apparatus according to any one of Claims 51 to 53 , including vertical guide wires extending downwardly from the hoists through the tilting box below the tilting box nnd terminating at tensioning means for the guide wires mounted below the tilting box, and guiding means on the 20 ends of the tong bar engaging said guide wires, whereby the tong bar is constrained to upward and downward vertical movement. 55. Apparatus according to any one of Claims 22, to 54 t including a quench tank of chilling liquid mounted 25 beneath the tilting box to receive a glass sheet lowered from the tilting box. 56. Apparatus according to Claim 55, including blowing boxes mounted above the quench tank to direct streams of cooling ^as against the faces of a bent glass sheet as it 30 Is lov/i red into Hie quench tank. - 158 - •I 0 2 5 r> I I 57 . Apparatus according l.o Claim 56, wherein the quench tnnl. i:: mounted ori a table of a lifting mcchanism, and conl.i o | mr-mi:: for the lifting mechanism is operable to rai.'if I.J.o quench tank to it3 position below the blowing rj boxer, just before a glass sheet is lowered through the blowing boxes. 58 . Apparatus according to Claim 57, including a support frame for receiving' a bent glass sheet mounted below the tilting box in a position to become immersed in the lo chilling liquid when the quench tank is raised, and means for actuating said glass engaging means when a glass sheet is engaged in said frame to release the sheet into the frame. 59. Appara according to Claim 57, including a weir lr> defined in the quench tank by the upper edges of walls of an elongated rectangular slot which opens upwardly towards the interspace between the blowing boxes, the walls of which slot define a moat at tho top of the quench tank around said slot, and means for circulating chilling 20 liquid upwardly through said slot to flow over the weir into the moat thereby accurately defining the location of tho upper .surface of the chilling liquid close to the bottom of the blowing frames. GO. Apparatus according to any one of claims 21 to54 , 2', wherein said thermal treatment moans comprises an anneal-in/: enclosure mounted for positioning below said exit month for receiving a hot glnr..-: r.):eot to be annealed. . Apparatus ::ec«>r:! i hi', to '"I a i >n 60 > win-rein I fie anneal i >•••; I'liclo.' re in .none t ed <>ri a hori t nl i.rncl'. for jo moviieal. Iter i a ! ly into position be lev; the exit mouth. - 159 - 62. A method according to Claim 1 of shaping a hot glass-sheet, substantially as herein described with reference to the accompanying drawings. 63. A shaped and thermally treated glass sheet produced by a method according to any one of Claims 1 to 19. 64. a bent and toughened glass sheet produced by a method according to any one of Claims 12 to 16, or Claim 6 2. 6r». A bent and annealed glass sheet produced by a method according to Claim 11. 6 6. A laminated glass unit comprising a toughened glass sheet and an annealed glass sheet produced by a method according to Claim 19. 6 7. Apparatus according to Claim 20 for shaping a glass sheet, substantially as hereinbefore described with reference to the accompanying drawings. F. R. KELLY & CO. AGENTS FOR THE APPLICANTS. -160-