DE1471965C - Device for drawing glass using the float glass process - Google Patents

Description

Οι 471 965

1 2

The invention relates to a device for pulling while one edge, generally both opposite one another of glass using the float glass process, existing edges, the glass layer to another Standing out from a molten bath of a glass exposed to liquid pressure that is just as great immiscible, heavier material, on which can be, but does not need, like the one, the one on the from a glass melting furnace the liquid glass is applied to the 5 glass edge on the metal surface, given and over which it is guided, cooled and thereby of course the edges soften in thickness is peeled off as a glass ribbon, characterized by from the part on which another liquid refractory Side walls that were subjected to pressure on the weld pool. Suspended by appropriate are, preferably to below the surface of the choice of the middle sections of the glass Melt bath range on both sides of the outflow ίο any pressure exerted before The opening of the glass melting furnace begins with the layer of starch produced on it and extend in the direction in which the glass is drawn. Strength to be maintained. Knows the layer every jch

It is known. To make sheet glass by not having the desired thickness on it, then it can be on that a glass ribbon or sheet of glass is made due to the fact that molten glass flows, the surface of a bath of molten metal, a band of the desired thickness is produced lets swim. that by choosing the appropriate pressure,

In the manufacture of "floating glass" (float the apparent densities of the glass in relation to

glass), the composition of which is modified by hand in the bath.

Usual table or window glass or other soda lime glasses as described in German Patent 1,264,696 is similar to is written when using 20 is, the middle section can be a layer molten metal, e.g. B. a bath of tin from molten glass on a higher level or a tin alloy that supports molten glass as the side edge portions and poured directly onto the metal bath, the glass keeping the surface of the glass layer level floats freely on the bath and closes at the ground if one has the molten load on it so-called "equilibrium strength" containing an equal metal. Tank due to non-wettable weight achieved. The exact walls are divided into three chambers by the glass at the same time, Weight achieved strength depends on the coherence- whereby the height of these walls is the desired Settlement of the glass and the metal bath. At the same level as the middle chamber. The side Soda-lime glass and one made of tin or pre-sections of the dated in the two outer chambers The bath is made up of pewter and the 30 metal-supported glass layer has equal equilibrium strength a fr: i floating glass weight strength, while the middle part of the glass layer about 0.69 cm. Even a ve formed layer of glass achieves a strength that makes all the difference tied, that one of the gloriously viscous is less in the bathing areas than the evasive one Has strength, if it is on the weight strength, the difference being the bath level molten metal floats, remelting 35 is less than the equilibrium strength of the glass. and strive for the strength of equilibrium. Appropriately, fJie can be continuous

Less than equilibrium thickness layer or ribbon of floating glass can be made by melting the layer by flattening a ribbon of equilibrium glass of one weight from the glass melting tank, one protruding in the direction of flow 40 Outflow opening directs the tensile force acting on an already stable bath of molten tin. As the cut of the continuous ribbon is applied, molten glass is applied to the tin plate in one A tape with a relatively thick but narrow layer from the equilibrium strength deviating from the described thickness can be set, the edges of the melted can be produced by other methods, 45 zen layer due to the high temperature of z. B. by changing the apparent specific gravity of the glass and bath on the bath and forming one of the glass in relation to the specific gravity of the floating metal bath, bribed from molten glass, while the glass is placed on the body, the larger dimensions and dnc maintaining the application temperature, or by exhibiting constant strength. Such a way of working the molten glass layer through 50 is described in US Pat. No. 3,083,551, a metal bath lying in two planes is supported The existing metal bath layer is supported on a different level than the one on which it can spread freely and achieve its balance between the glass edges and the total surface of the glass, it turns out, is essentially on the same level. 55 that a considerable length of the molten bath is required before the ice layer is described, as is required in the German OI laying and the location (delimitation) of the layer cannot be tails effectively achieved by being precisely determined. If, on the other hand, a layer of glass directed onto the floating glass or part of it, the molten bath, selectively exerts a liquid pressure which deviates from that which is cooled to be uniform in dimensions and which is not applied to the liquid pressure while it is passing the boundary walls of the glass covered metal surface and / or touched on the Tankcs, so result from the 'subordinate sections of the floating glass, z. B. different flow rates within which the edges of the glass ribbon is exerted. In the 65 layer, which was caused by the contact of the viscous glass in most cases, it was found to be advantageous if, with the boundary walls, this deviating liquid pressure only caused undesirable fluctuations in the strength.
Part of the surface of the glass layer is applied according to the method of the present invention

a layer of molten glass is poured directly onto a bath of molten metal without that the disadvantages occur with the previous methods of making a floating Band of the desired size occurred. Molten material is used to practice the invention Glass is guided directly onto the metal structure at a controlled speed while the glass is in is in a substantially flowable state, d. H. a temperature of about 930 to 1200 "C. The flowed out glass dispersed inert on the molten metal bath between the inner surfaces of the glass Sidewalls and is withdrawn from this location at a controlled rate, which causes the Width and thickness of the layer still in contact with the wall can be determined. The layer is already touching then the side walls no longer when the glass is still flowable, d. H. preferably at one temperature of more than about 930 C in. case of hiatron-lime glass and seldom less than 9? .O C what the subsequent surface treatment is facilitated without the need to reheat the glass would.

It is most beneficial. when the side walls ar. the surface of the metal bath that of the boundary of the molten glass serve, in the direction of the Bandbewecung from the width of the agitated Spread the layer up to the desired binding width at the end. The refractory walls bf made of a material slightly different from the molten glass can be wetted, and the V ande preferably contain in their endals cut, seen from the glass spout v. 'iter below, a refractory part of that jre'.chmelted glass cannot be wetted. the The speed of the glass escapes from the discharge opening on that located between the walls that diverge at a certain angle Bath and the speed with which the glass aiii moves the metal bath forward and thus out The area between the diverging forests is removed, so in relation to each other set that one between the wetted, - !, ι .inandertretenden walls and the melted (d. II. flowable) layer of glass occurring (iteiiz surface attraction strives to the Thick between the diverging walls the amount of molten glass present.

The attraction between the wetted walls and the molten glass is canceled at the l-jid portions of the diverging walls by the non-wettable refractory portions. If the strip thickness; \ n this point the Gleichgc'.vichtsstärke or more et ranges, a further lateral expansion of the glass can be prevented, thereby making it gehallen on the desired thickness and width that it has reached at the end portions of the passing apart walls . If the tape has less than the equilibrium strength at this point, it can be prevented from becoming thicker again.

Regulating the thickness and width of the layer of molten glass? at the point where they the the Edges touching walls, or something beforehand, where the desired thickness has been reached, can thereby crfoleen. that you have to go to the different sections the glass layer exerts a different pressure or that you have already mentioned provides a bathroom on two levels. The G | assc.iichl can also use this on a v> Be kept in a hurry than the equilibrium exhibiting strength that one pulls on one further below, already solidified section of the layer applies or such a tensile force combined with a different pressure. It is ίο easy to see that when the Layer thickness by applying a different pressure or one lying in two planes Molten metal bath has a very high uniformity of dimensions of the strip in the Width and thickness can be achieved. The band strength can not only be maintained, but by choosing the appropriate pressure differential of the molten one lying in two planes Metal bath or the tensile force can also be modified in the desired manner.

There are several important advantages in practicing the present invention Since it is z. B. is possible by this method, the lying directly on the tin bath molten Glass is much stronger and, in relation to the distance the glass has to cover in the bathroom, much to be thinned and widened faster than is possible with a free-floating layer for any given amount of glass flowing out of the tank and any given linear Speed of the resulting tape a wider and thinner tape can be produced. Out It follows from this relationship that, according to the invention, it is possible for a given linear Belt speed and a given final belt thickness within a certain time to produce a wider band and to facilitate processing in a larger quantity of glass.

You can also use a layer of glass in a flowable Establish state that has less than equilibrium strength. The same principle can can also be applied to any desired strength down to the equilibrium strength at shorter To achieve travel distance of the belt by virtue of the interfacial attraction between the molten glass and the diverging wettable refractory walls, the one Aiming at reducing the thickness of the glass. The exact position and width of the molten layer can be so be regulated that the subsequent operations are facilitated, z. B. the application of pressure within one above the glass. Pressure chamber. As the wettable walls of the floating Oppose a broad transverse bar against the glass layer, any tendency of the band to move sideways to the bath / ti is also reduced. Through this, that the bath expands over the entire desired width before it diverges Walls no longer wetted, make the edge sections of the tape, which are during the separation warped, but relatively constant and independent of the total bandwidth Have width, only a relatively small part of the finished tape.

Fig. 1 shows a longitudinal section through an apparatus with the glass according to the invention Process can be produced in which devices for deposition of a glass layer aut

5 6

a molten bath and to regulate its 14 without damaging its surfaces durcl

Width, thickness and position on the bath and Vorrich- pull or execution rollers 22 from the tank au

Are shown hanging, with which a roller conveyor 24 is optionally drawn,

different pressure on the surface of a tank 18 consists of a refractory bottom

a bath of molten metal lying s part 26 and a refractory ceiling part 28, which with

(ilasbandes is exercised; connected to each other and by an appropriate

F i g. Figure 2 shows a horizontal cross-section of the sealing device, with the exception of one inflow

along the line 2-2 in FIG

ment of the arrows. are sealed. The seal shown is a bubble

In Figures I and 2 of the drawings, a bellows-like device which allows dci

Sole or lip 10 shown, which vorr with the side ceiling portion 28 of the tank for repairs, etc.

Limiting surfaces 11 ″ and 11 6 a is lifted off the outlet bottom part 26 without fireproof

end of a glass melting furnace 13 located discharge parts removed and then these removed parts

opening 12 having to be restored with a generally rectangular transverse shape. The bottom part II

cut forms. The outflow opening 12 from 15 contains the molten metal 16 and is in a

Stepping glass forms a layer of molten forming and surface working zone 26a and

Glass 14 on the Oberllächc one in a tank a cooling zone 26 b divided. These zones are through

18 contained, made of molten metal! A submerged partition 30 from one another against bath 16. The metal can be tin. separates, through the convection currents in the molten tin alloy or the like. Act. One of the glass »o n metal can be significantly reduced. In the flow regulating shut-off device IS and a cooling zone there are also other submerged slides 17, which are each adjustable in a known manner, partition walls 32, through which convection currents are suspended in bar, work with the outlet opening of this zone are regulated. The level of the metal

12 together and regulate the glass flow from the furnace bath is through a at the outlet end of the tank

13 / um molten metal bath 16. as attached weir body 36 and through a supply refractory Seilcnwand 19 a and 19 6 are approximately line 38 regulated. The metal level is provided directly next to the outflow opening 12 and, if necessary, always kept at such a height, extend from this along the, in contact with that the treated glass ribbon does not with one of the immersed in and above the surface of the metal bath within the tank 16. Preferably, they also extend below the walls or partitions that come into contact Surface of the metal bath. They will be purpose- The feed line is in a wall moderately supported in their position, e.g. B. from the tank 18 and is with a suitable source for the tank walls 18 and connected by molten metal, not shown, with which the tank hanging devices. however, they can also be filled on.

anchored in the tank structure in another way 35 The space within the side and end

scin. The partition walls 19 a and 19 ft give way to the walls of the tank 18 between the ceiling part 28

Direction of glass movement apart, d. H. of and the surface of the metal bath is through the

the outflow opening to the opposite end of the end face of a surrounding wall 40 in two chambers

Tank 18 divided b of a width approximately the intermediate chambers 28a and 28th This wall depends on

space / wipe down the lateral boundary surfaces 40 of the ceiling 28, their side sections are located

11a and 11b corresponds to one of the desired distance from the walls of the tank 18. so

Bandwidth corresponding width. The side walls form a gas gap along each side of the tank

19a and \ 9b are preferably made of conventional 28c. In fact, the intermediate

Lichem refractory material, such as firebrick, spaces 28c continuations or bulges

as it would normally be for the construction of glass tanks 45 of chamber 28a.

is used and that of the melted in each gas chamber or pressure zone * ird through

Glass can be wetted. On the lines 42 and 44 located below, each with a suitable

The end piece of the side walls 19 a and 19 ft are a source for the pressure-generating gas (not daree-

refractory inserts 21 α and 21 b. which is off) are connected, a gas that

a material such as graphite, which is inert to the 50 parts, such as nitrogen od. Del., under

molten glass cannot be wetted and pressure is initiated. The gas is preferably heated,

the detachment of the molten layer of the in order to cool the zones and the treated

to avoid floating glass 14 from the side walls of the glass. The pressure under which the gas

19 α and 19 b facilitated. is introduced into the zones 28a and 28c can vary from around the metal of the bath 16 in molten 55 to the pressure at which the gas in the zone

To keep state Wärmeregulierungsvor- can be initiated b 28, schwimrichtungen thereby Stärke'der. how electrodes 20. in the bottom of the tank facing glass layer will be attached as below 18 - as will be described from the drawing. For reasons of temperature is or can be in the molten tur control, the pressure zone 28ft can be immersed through walls of metal and thus affect the bath temperature 60 or partitions 46a, 46ft, 46c and 46a ". The electrodes 20 are further subdivided in a conventional manner

Near the ceiling of the tank 18 are radiation sources connected to a suitable power supply (not shown). Each electrode can be individually fitted with heating devices 48 which are closed and regulated so that within the outlet and inlet ends of the tank the desired various sections of the tank 18, such as the 6 ₅ glass temperature, are maintained - as the following description will show , the drawing shows - in both Druckzo—. preset heat gradient can be generated. After radiant heating devices are conventionally treated in the tank 18, the glass ribbon is lent in an electrical manner (not shown)

7 8

Connected to the power source and can be used to regulate the flow rate while moving through the bath.

Temperature chambers can be switched on individually. When opened in the direction of the outlet end of the tank

the control devices are those 18 moved forward.

of the conventional kind, which are not described in detail. Given the 5 end of the walls 19 a and 19 6 a previously infested, cooling devices of the correct width and thickness can be installed above the cooling zone, if the loading devices are attached to ensure that the glass removed from the bath is at the correct temperature on- outflow opening and the forward movement of the so-called, molten layer on the metal bath regulated

The main- of the side walls 19 and 19 b and the α Grenzflächenten within the tank region above the geschmol- be io, the degree of divergence steeping is Zenen metal prevailing pressure; by using liquid pressure tightness between the molten glass, 50 hung at the inlet end of the tank 51, on the outlet and walls 19 a and 19 6 through the wetting outlet end of the tank and through gasket 54 that are accounted for with the walls with the glass the wall 40 is connected, the loss of 15 will have to. The width is prevented by the inert gas from the zones. The sealing walls are regulated, and the thickness can be 51 and 54 contain a multitude of grooves, which are therefore separated from one another by webs with a constant glass throughput, which are set and regulated by the fact that the tape is conveniently closed with a curtain «From pressurized speed at the point where the belt carries the standing inert gas, e.g. B. by a perforated ao walls no longer touched, regulates. The scheme tes tube 62, are provided. The upper seal of this speed, which is normally done by the seal arrangement 51 at the entrance is similar to drawing rollers, which can be constructed on a solidified part and the pressurized inert gas of the strip below the metal bath, is fed through pipe 62 a. by using powered ones (not shown)

A lower seal 52 at the exit end of the as knurled wheels can be relieved that the edges of the dei Tanks 18 is built so that they have a gaseous support- floating glass layer in the middle between

Forms device for the glass, so that end sections of the diverging

side walls and the outlet end of the molten tank protected from contact with the tank.

will. According to Fig. 1 and 5, through filling chamber 70, zenen metal baths touch,

which are pressurized with a suitable source of 30 At a point the length over which the

existing inert gas is connected, through openings 71 side walls 19 a and 19 ft extend, the happens

in a multitude of grooves, which are formed by webs ahn- glass layer 14, the seal 50 at the entry point

Licher design as in the case of the upper seal separated 18 a in the end portion 28 a of the tank 18. A

are. Gas supplied. Gas, which is inert to the metal, becomes in the Rohi

The device for regulating the level of the initiated 35 62 α, flows down and impacts aul molten metal in the bath 16 includes the weir- the glass, whereby the interior of the tank 18 body 36 and the above-mentioned supply of the inner area near the outflow line. The weir body 36 consists of a plate opening 12 is insulated. A similar gas is introduced into the refractory material which can slide into a filling chamber (not shown) in the refractory tank part, with recessed slots. The weir body 40 the pressure must be sufficient to the gas in diesci is through suitable devices, e.g. B. screws, chamber through the openings in the grooves of the unin the vertical adjustable so that the level of the direct seal 52 to flow and the band of molten metal can be regulated according to the thickness of the glass produced at the outlet end 18 6 of the fixed tank divider . To keep away from.

Weir body delimits one side of a basin 36 ft, 45. In general, this gas is excessive (by not allowing the other side and the bottom of this basin-indicated devices) to be heated to a temperature by the walls of the tank 18 or a sufficient amount Cooling of the other suitable refractory material should be limited. To prevent glass. Normally the temperature line is through the wall of the tank 18 carries the gas flour fed to the pipe 62 a, it is at one end with the basin 36 ft 50 than 540 ° C, it is preferably between in connection . Through this line the 870 and HOO ³ C. The temperature of the gas fed to the filling molten metal in a collection chamber (not shown) will normally be vented through containers to be refreshed and at 260 ° C.

of being heated. From this collecting container the glass leaves the side walls 19 a and 19 I

is through the above-mentioned supply line 55 in the chamber 28 a with a predetermined one

molten metal is pumped into the tank 18. Width and strength. The graphite inserts 21 1

The drain line contains one. Siphon, d. H. one and 21 ft make it easier to loosen the melted

U-shaped piece in the line through which the to-layer 14 from the walls 19 a and 19 ft to one

atmospheric air enters the tank 18 prevents certain point and the desired band

that would oxidize the metal of the bath. 60 width. This detachment will continue to facilitate

During operation of this apparatus is melted through the acute angle and the sharp cut-glass from the tank 13 from the outlet 12 line, which is at the intersection of the inner surfaces dei on the metal bath 16 between and in contact with walls 19 a and 19 b and their End faces on the diverging walls 19a and 19 ft below located end portions of the walls. The recessed layer is narrower and form 65.

thicker than the band ultimately desired. The moment the layer melted

Layer of molten glass spreads on the zenen glass from the side walls 19 η and

Metal bath between the walls 19a and 19ft from 19 6 in the previously determined thickness and width "

9 10

solves, it comes out of the chamber 28 a through which can range. When the layer or the tape

Seal 54 under the peripheral wall 40 in the 14 of the dsn diverging side walls Chamber 28 6. The width of the band 14 protrudes over 19 α and 19 6 at a below equilibrium strength

the space enclosed by the V / and 40, dissolves lying strength, preferably less than

so that a narrow margin extends over the edges of the 5 0.51 cm, e.g. B. with a strength of 0.48 or

Wall 40 extends out into the chambers 28 c. 0.32 cm, which indicates the thinning influence of the

The tubes 62, which are arranged in the wall 40 by pulling force between the wetted walls 19 a, are supplied with sealing gas, which impinges on the and 19 6 and the molten glass layer back-edge portions of the band 14 that is to be fed, so the pressure difference would be which is located immediately below the walls 40; on io is necessary to increase the strength of z. B. 0.48 in this way will reduce the chamber 28 6 by a gas 0.32 cm (or in the case where the shaped curtain separated from the chamber 28 c. Layer away from the side walls with a strength of this gas is supplied under a pressure that loosens from 0.32 cm, which to maintain the pressure is equal to or greater than that of the pressure required for both band strength), remain the same, on the side of the curtain prevails. The temperature of the 15 ie 0.88 g / cm ² .

the front portion and the side portions of this die between the edge 28 6 and the one on the

Walls opposite the intermediate wall 46 a zugelei- edge of the disc or the band prevailing

In general, the melt pressure differences should in no case be so high

approach the temperature of the glass, it should be little, however, that the tape breaks, and they are seldom lying

at least be high enough to allow the band * ao to cool over 22 to 44 g / cm ² .

edges to less than the melting temperature

prevent. when detaching from the side walls 19 α and 19 6

The band floating on the metal surface absorbs more than the equilibrium strength of the glass.

14 moves forward through chamber 286 and shows this greater strength being sustained

will finally, after it has passed the seal 51 , by taking into account the pressure difference between the chamber

has siert, from the tank 18 between the drawing rollers mer 28 6 and the chambers 28 c changed so that

22 is pulled out, which optionally under a pressure prevailing in the chamber 28 6

exert sufficient tension on the belt so that the chambers 28 c are located,

this remains in motion. The prevailing in the front part of the chamber 28 6

When the strip 14 passes through the chamber, the temperature seen corresponds to the melting temperature

With 28 6 the temperature of the glass ribbon becomes sufficiently high. To the end, d. H. behind the

hold to a viscous flow of the glass inner intermediate wall 46 a, the temperature is so far

half of the deforming and surface processing that the output of a permanent reduced

To facilitate zone of the tank. During this time the tape is ensured by the contact

the surfaces of the belt smooth out, the one with the rollers at the end of the tank

Strives for equilibrium strength, the size of which is not damaged, e.g. B. 320 to 540 ° C or Pressure difference between chamber 286 and less,

depends on Kamemrn 28 c. Of course, this will be done through the tubes 62 along

The pressure chamber 28 6 can be used to the walls 40 introduced gas under a pressure to either the strength of the melted 4 ° or at a speed, the layer of glass, with which it extends from the side walls, is sufficiently high to the pressure difference between 19a and 19 6 dissolves, to maintain or to change the thickness of the chambers 28 6 and 28c to maintain the molten layer. As already mentioned, the temperature in particular will further reduce the layer thickness. temperature of the gas, which in this way depends on the pressure required in the chamber 28 6 range 45, in which the tape is kept at the melting temperature of the desired strength and the external pressure, is supplied by heating in, ie the pressure in the chambers 28 c, brought into the essential on that of the glass. Other than the edges of the tape or layer, the glass has to stretch at the more distant ends of the sheet. If a tape is to be produced, the little chamber, z. B. behind the partition 46 c, cooled down than the mentioned equilibrium strength of about 50, and the lines 62 in these Be-0.69 cm, the pressure in the chamber should reach the walls 40 gas is normal 28 6 by at least 0.044 ² above that of the way much cooler, its temperature is at the edges of the melted band, ie in the th above that of the pressure prevailing on the opposite side of chambers 28c. this wall sections located tape

The tape seeks z. B at a thickness of 0.48 cm 55 and can advantageously be much less,
to stabilize when the pressure difference

Is 0.48 g / cm ^2. example 1

The degree of stabilization depends on the duration and

the temperature. It is therefore easily possible to use a 30.5 cm wide discharge opening wire

Thickness extending from the side walls 19a and 19 b 5o molten glass from about 1150 ° C with "like

dissolving glass layer of, for example, the constant speed directly on a bath;

weight thickness of about 0.69 cm passed on a thickness of molten metal, the .nus 100 ° Ό Zinr

to reduce about 0.32 cm by insisting for one with a density of 6.52 g cm ³ at 9 £ 2 'C

suitable pressure difference of about 0.88 like ² The glass was composed of 71.38 percent by weight SiO ₀

between chamber 28 6 and chambers 28 c 65 13.26 percent by weight Na ₂ O + K ₂ O. 11.76 Ge "

ensures and sufficient time for the tape to weight percent CaO, 2.54 weight percent MgO

Passing the deforming and surface processing- 0.75 percent by weight Na ₂ SO ₄ , 0.15 percent by weight

provides the zone so that it has the lower strength - Al ₂ O ₃ , 0.11 percent by weight Fe ₁ O ₃ and 0.06 Ge

weight percent NaCl and had a specific weight of 2.542 g / cm ³ .

The tank for the molten metal corresponds in its construction to the tank shown in FIGS. 1 and 2, it is', divided in length into a deforming and surface-working zone and a cooling zone. In the deforming and surface processing zone, the metal is kept at 1040 ° C. In the cooling zone, the temperature of the metal in the direction of the glass passage lies between J 040 and 540 ° C. The space above the metal under the ceiling 28 of the tank 18 is divided into two pressure chambers; Pressure-generating gas is fed into each chamber. Before the addition, the Gt-s is heated to 1040 ° C. The first chamber 28 a (and also the chambers 28 c) is kept under a pressure slightly above atmospheric pressure, ie 1.32 g / cm ² , while the second chamber 28 & under an overpressure of 2.2 g / cm- is held so that the pressure difference between the two chambers is 0.88 g / cm *.

Refractory side walls 19 α and 19 fr, which can be wetted by the molten glass, touch the surface of the metal bath, giving way to a space between the inner surfaces from 30.5 cm to a maximum gap of 0.92 m at their lower end points and extend in the Direction of glass flow over a distance of approximately 2.45 m. Each of the side walls contains a graphite insert at its lower end point 5.1 cm long.

The glass layer located on the surface of the tin bath 16, which wets the diverging walls 19 α and 19 b , reaches a total thickness of about 0.32 cm over its entire width when it is close to the graphite inserts 21 α and 21 b at the end of ier side walls 19 α and 19 b is located. At this point the glass is kept at around 980 ° C.

The tape or sheet then slides under the second chamber 286. The width of the sheet exceeds the width of the second chamber 286 so that the sheet edges extend laterally beyond the outer side edges of the chamber. Due to the pressure difference between the chamber 28 b and the chambers 28 a and 28 c, the central part of the band located under the chamber 28 b is kept at a thickness of 0.32 cm.

From above acts on the glass ribbon or the layer of radiant heat generated by heating elements 48 , which contribute to the fact that the glass maintains its melting temperature over the entire thickness and on average over the entire range located under the chamber 28 b. At the end of the tank? for the molten metal, the tape is then ^{cooled to around 540 r} C, whereupon it is pulled out and makes contact with the meta !! loses. The tape thickness remains essentially 0.32 cm. the surfaces are smoothed by fire and even, with the exception of the edges, which are bent up. There? The tape is pulled out at a speed of about 1.22 m min.

The inside and outside of the second chamber are separated by a gas curtain as explained in the drawing, the gas being under a pressure of. 2.2 ε'cm ³ stands.

Of course, in the practice of the invention, instead of the molten Tin or tin alloy, other permanent molten materials can also be used, the specific gravity of which is higher than that of the glass ribbon: such as Lead, lead-zinc alloys or the like and metal salts with a specific weight above about 2.5) and that which is stable, essentially non-volatile, at the melting temperature of the treated glass Liquids are.

The use of an intermediate gas partition is an effective seal, however, other devices can also be used. The bottom edges of the walls 40 can e.g. B. so close to the tape that essentially no shrinkage occurs and that the desired pressure difference can be maintained.

The ratio of the bandwidth to the pressure chamber can be changed. Should z. B. thicker disks are produced, the tape needs not to extend beyond the outer edges of the walls 40, since the gas fed in through pipes 62 generates the required pressure difference. In this case it can be sent in this way Gas at the belt edges generate an about-atmospheric pressure, and the chamber 286 can open atmospheric pressure.

The use of sidewalls, which can be wetted by the molten glass, in conjunction with a glass stream flowing on a metal bath, facilitates the achievement of any thickness in such a molten glass layer, the distance to be covered for a given glass volume being shorter than with one a freely floating glass layer (ie the marginal edges are not limited) or a glass layer whose marginal edges are limited by a non-wettable substance. The present invention can of course also be used to advantage to produce a ribbon whose strength is less than the equilibrium strength of glass floating freely on a metal bath. In addition, the present invention provides for the use of the fP.ind) edges touching, delimiting, fettest walls made of a substance that cannot be wetted by the molten glass, the walls delimiting the edge of a molten glass layer and one above the Produce equilibrium strength lying band strength, which is then maintained, z. B. by using a pressure chamber arrangement as shown in FIGS. 1 His 5 is shown. It is also envisaged that these non-wettable sidewalls will be used in conjunction with an orifice which directs the molten glass directly onto a metal bath so that the position of the strip or molten layer at the point where it reaches equilibrium strength can be precisely controlled.

Of course you need the walls that move together. e.g. walls 19a and 19 /), 200a and 200 h and 220 a and 220 b. which is the width. · Starw and position of the glass layer control, not "! Calibrate manner as described built / u be to operate in accordance with the invention. For example, the divergent walls, which extend from the outflow opening of the glass melting tank, can also represent a part of the tank and

replace even parts of the tank walls containing the molten metal, d. Ι_ form.

The present invention can also be used in the context of a layer of molten, i.e. H. Flowable glass are applied, which is at the beginning between the wettable side walls a strength below equilibrium strength, d. H. 0.51 cm or less thick on the Metal bath is passed. The reduced thickness of the layer set at the beginning can be retained or possibly further reduced by the attraction of the wetted side walls. It is also possible to use a ribbon of glass beforehand, e.g. B. by rolling, with a below equilibrium Form strength that after the dimensions by cooling after the deforming process have been stabilized, further widened and / or reduced in strength or maintained at this strength while the surfaces are improved by viscous glass flux by using the ao Tape heated so that it is easy to flow while the edges wet the refractory walls.

In the previous embodiments of the invention was with pressure differences or in two Plain baths worked to maintain the thickness and width of the flowable glass layer at the point of separation from the wetted refractory walls; this dimensional stability can, however, also be achieved through a different measured temperature control can be achieved. Instead of a pressure chamber or one in two levels lying bath, which divide directly into the one that regulates the width, thickness and position of the glass layer Follow the glass walls, the temperature of the glass at the point of separation can be reduced to a value (usually to more than 760 ° C and preferably to around 820 and 870 ° C), where the glass viscosity is sufficiently high, in order to significantly change the belt dimensions in the time available due to the existing ones To prevent forces, and yet sufficiently low to prevent the Ba.ides from separating to allow the walls. Optionally, in cases where the glass is flowable, i. H. at a Temperature of more than about 930 ° C, the dimensions - if the starch is not Strength of equilibrium acts - at the endpoints that regulate the width, strength and position of the tape, diverging side walls through parallel running sidewalls are kept above or below equilibrium, whereby these Extend sidewalls along the bath surface from the end points of the diverging walls. If these parallel walls can be wetted by the glass, a can on the Endpoints of the diverging walls less than equilibrium strength tape due to the attraction of the parallel, wetted walls on these smaller, thinner ones Dimensions are kept while the temperature of the glass according to one for the surface finishing Effect of sufficient time to increase the glass viscosity as described reduced will. The glass is then pulled out of its position between the walls. Is the Glass thickness more than equilibrium strength, so need the parallel side walls of the Glass not to be wettable.

Claims (4)

Patent claims: 1. Apparatus for drawing glass according to the float glass process, consisting of a molten bath made of a heavier material that cannot be mixed with glass, onto which the liquid glass is applied from a glass melting furnace and over which it is guided, cooled and pulled off as a glass ribbon, marked by refractory side walls (19rt, 19b ), which are placed on the molten bath (16), preferably reach below the surface of the molten bath, start on both sides of the outlet opening (12) of the glass melting furnace (13) and extend in the direction of pulling the glass . 2. Apparatus according to claim 1, characterized in that the refractory Seitenwändc (19 (7, 19 b) diverge in the pulling direction of the glass. 3. Apparatus according to claim 1 or 2, characterized in that the refractory side walls (19 a, 19 6) consist of a material such as fireclay, which is made of liquid glass is wetted. 4. Device according to one of claims 1 to 3, characterized in that the refractory side walls (19 a, 19 b) at their E ^r .de in extension pieces (21a, 2Ib) made of a material such as graphite, pass from the liquid glass is not wetted. 1 sheet of drawings