NO147708B - DEVICE FOR THREE PRESSURE CONTROL VALVE FOR INDIRECT EFFECTIVE PRESSURE BRAKES FOR MONITORING FILLING OF A CONTAINER - Google Patents

Description

Method of supporting a plate of glass or similar thermoplastic material.

This invention concerns a method for producing a web of glass or a similar thermoplastic material, where the web is allowed to rest on a plurality of supports, of which at least the part in contact with the glass is made up of a liquid.

According to the invention, the glass web can be in a plastic state, without its flatness being affected by the discontinuity of the aforementioned supports, provided that the glass web does not stop at these, but instead moves on in relation to them.

According to one embodiment may

such supports are obtained by completely filling recesses, which are arranged in the solid underlying layer, with a liquid which practically does not react with the glass or with the solid underlying layer. The above-projecting parts of the liquid whose surface protrudes and which in the following for the sake of simplicity are called projections — support the moving glass web due to their surface tension, without the glass web coming into contact with the solid substrate, except where necessary at the edges of the glass track.

The aforementioned recesses can have different dimensions and shapes: They can e.g. be circular, elliptical, rectilinear or non-rectilinear channels.

According to another embodiment

the aforementioned protrusions can be obtained by placing a liquid — which does not react with and does not wet glass — on limited areas of the solid (massive) support, which

can be wetted by the liquid in question and which is anchored in predetermined areas of the support part.

For carrying out the present invention, it is not necessary that the movement of the glass band in relation to the protruding liquid parts should result in a displacement of the glass web. If the glass web is kept stationary, in a plastic state, e.g. as long as it is subjected to a thermal or chemical treatment, its support - according to the invention - is ensured, without the glass sheet touching the underlying solid layer in the spaces between the liquid projections, provided that the latter are displaced under the glass sheet, so that their contact with the glass path is constantly changing, e.g. by producing an alternating movement of the fixed support part, which carries the protruding liquid parts.

By means of the method according to the invention, the glass track can be supported without the underside of the track coming into contact with solid bodies, which could damage the track. Furthermore, the web can be transported in a plastic state, while at the same time it can be subjected to mechanical and/or chemical treatments in such a state. Furthermore, it becomes possible to transport the glass sheet through zones of gradually decreasing temperature so that the sheet hardens and is finished without its surface changing.

In the method according to the invention, carrier liquids of different types can be used, where special consideration is given to the different temperatures to which the glass web is eventually exposed.

Each individual meniscus of the carrier fluid will, as the glass path is moved forward, be deformed in a non-symmetrical manner; the easy entrainment of the product by mutual displacement results in a reduction of the radius of curvature of the meniscus at the front and an increase of the same at the rear. The braking of the movement of the glass web caused by this double deformation is the greater the stronger the entrainment movement. This phenomenon therefore has a self-regulating effect.

Furthermore, this braking will counteract the force that drives the glass band forward, so that if the glass is in a plastic state, the stretch in the web will seek to pull this and make it thinner, without it being necessary to hold the web using mechanical means in front the traction zone. It is only necessary, in order to avoid narrowing of the web, that its edge parts are maintained, e.g. by means of small rollers, which are used when pulling the glass in a vertical direction, or by means of means according to the invention, which will be described in more detail below.

It is possible to influence the braking forces, e.g. by changing the degree of inclination of the solid body which carries the liquid projections, or by changing the number and dimensions of the aforementioned projections.

For example, the braking forces can be canceled out or even a propulsive force can be created for the glass band by allowing the surface of the fixed substrate to slope sufficiently downwards in the direction of movement of the glass band. If, on the other hand, this surface is allowed to slope upwards, the braking effect increases, and with it the tension in the track, so that it is stretched, if the track is sufficiently plastic in this zone, whereby the track becomes thinner.

The inventors have found that in order to achieve these important effects it is advantageous to use a larger number of liquid projections, so that the braking effect exerted by the menisci is correspondingly increased. The braking is probably very small at each projection, but the combined effect on the glass path of numerous projections becomes significant. The dimensions, number and size of the spaces between the protrusions are adapted so that the soft glass cannot sink down between two protrusions and thereby come into contact with the solid surface on which the liquid itself is placed. If the glass path were insignificant in relation to the liquid, such a sinking would occur sooner or later. It is therefore necessary that the glass is moved so that there are constantly new support points on the glass and that no sinking takes place. The same result can be achieved if the liquid projections are moved with sufficient speed under a stationary glass path.

There is thus a relationship between the speed of movement of the glass web and the free space between each of the liquid projections in the direction of movement of the glass web, and this relationship naturally depends on the viscosity of the glass web, i.e. on its temperature. Experience has shown that with ordinary glass, which has been heated to 900° C, no deformation will affect the flat state of a glass path that moves at a speed of 1.50 m/minute, and where the distance between the liquid projections is about centimeters in size.

The above-mentioned supporting liquid protrusions can be arranged in the form of ribs by filling narrow, closely spaced parallel channels right up to the top edge, which run transversely in relation to the direction of movement of the glass web. These ribs can be divided in their longitudinal direction into a number of separate zones, which possibly run at an angle to each other.

The ribs can be rectilinear, but it is also possible to arrange them in such a way that the top of the angles is in the plane of symmetry of the glass web and is oriented in the direction of movement of the glass strip. In this case, the braking forces mentioned above will be oriented obliquely outwards towards the outer edges of the web, and a component of these forces counteracts the narrowing of the glass web, but facilitates its pulling. An analogous result is achieved by using channels that have a curved course, e.g. is circular-arc shaped.

For the production of a flat glass path, i.e. a path that has a rectangular cross-section, the contact generators between the glass and the liquid projections should be horizontal, and it is necessary that all the projections are similar in one and the same horizontal plane. However, as mentioned above, it can be advantageous to use a support plane that slopes downwards in the direction of movement of the glass path, in order to cancel or reduce the braking forces in or even to provide a counteracting force by using a support plane that slopes upwards in the direction of movement of the glass path , to increase braking forces and increase traction.

This upward or downward sloping surface can, instead of being flat, be made up of a cylindrical surface, on whose generatrices the projections are placed, where each projection is, however, horizontal and practically perpendicular to the path's direction of movement. The variations in the curvature of the glass web that can occur while the web is in a plastic state, have no adverse influence on the web's final plane position, provided that the radius of curvature of the support part on which the protrusions rest is large, and that the glass web is then guided along a flat support, while the path transitions from a plastic to a rigid state.

The above-mentioned arrangement of the protrusions is only suitable for the production of flat glass, but it is also possible by using the invention to produce bent glass webs, e.g. cylindrical or with undulations. According to the invention, this is achieved by arranging the liquid protrusions on the surface of a solid body, the profile of which corresponds to the profile of the path one wishes to produce. In this case, one can e.g. use a large number of depressions of circular or elongated cross-section, which are placed in the cylindrical surface of the solid, underlying body, so that the glass band is supported as evenly as possible by the protrusions that the free surface of the liquid in these depressions produces.

In all cases, it is necessary that the glass path completely covers the depressions and the edge parts, as otherwise there would be a risk that the liquid could be partially driven out of the recesses, due to the pressure exerted by the glass.

According to the invention, the forward transfer of the glass web in a plastic state can be facilitated by causing the edge portions of the web to harden, e.g. by putting these in contact with solid, cooled surfaces. A simple method consists in allowing the underside of the edge parts of the glass track to slide on cooled, solid bands.

When starting an apparatus according to the invention or if for one reason or another you want to reintroduce liquid, it is sufficient that an excess quantity of the liquid is supplied to high points or simply to the inlet of the carrier part. The excess liquid that remains after the first recesses or cavities have been filled flows on and gradually fills the following recesses, and the remaining liquid is taken out at the other end of the device. If the support part is horizontal, the recesses can also be connected to each other through channels inside the otherwise solid block ccm form a support element; but such internal communication is not necessary at all. If the recesses are not interconnected, the carrier part becomes easier to produce, as in that case it can be made up of a plurality of elements which can be easily replaced.

In the embodiments described above, the indicated cavities, channels, etc., which are arranged in the underlying solid or massive support part, and which cooperate with a liquid that does not wet the support part, can be replaced — as indicated above — by zones of the same surface, which is arranged in the aforementioned support part and consists of a material that can be wetted by the liquid, so that it is anchored in its zones and forms an equal number of corresponding projections.

Such wettable zones consist of metals which, together with the carrier liquid, can form an "intersurface alloy". This is particularly the case when it comes to iron and copper vis-à-vis tin. The inventors have found that it is advantageous to choose metals which, while tinning on their surface, are not prone to develop corrosive cracks, e.g. molybdenum.

The choice of solid supporting material that does not get wet depends on the nature of the liquid used and on the temperature that occurs. If the liquid is molten tin, materials such as silicic acid or agglomerates such as sillimanite can be used at temperatures up to approx. 1000° C or slightly above.

You can also use graphite, which has the advantage that it is very easy to shape by machine processing, and that, due to its good thermal conductivity, it does not crack easily in case of heat shock, so that you can place heating or cooling devices inside the elements and thereby can easily control the heat treatment to which the glass web is exposed.

According to one embodiment of the invention, the liquid can be continuously brought into contact with the underside of the glass sheet through a plurality of openings in the fixed supporting element, either because the latter is porous or because special supply channels are arranged in the element. The actual support of the glass web then consists of separate drops, which eventually combine to form a discontinuous film or a series of successive films, which, after passing a certain distance along the fixed support, are carried away through specially arranged channels in the surface of the fixed support .

In each case, a major advantage of the method according to the invention consists in achieving a reduction in the contact time between the glass and the liquid support compared to the use of a continuous, liquid support, as the contact surface between the glass and the liquid becomes less. The risk of an attack reaction between the liquid and the glass is thereby also reduced.

Furthermore, when the liquid which forms the supporting projection consists of a molten metal, or alloy, e.g. of lead or tin, to provide a neutral or reducing atmosphere in contact with the metal to be protected, without it being necessary to place the entire apparatus in such an atmosphere. It is sufficient that the protective gas is driven into the spaces between the floating protrusions. If the solid substrate consists of graphite, the gas simultaneously protects the graphite by allowing the gas to penetrate into the graphite's pores.

A reducing atmosphere between the protruding parts of oxidizable molten metal will not only protect the metal against oxidation, but will also protect the glass against a possible reaction with the molten metal. The inventors have particularly found that if silver of over 960° C is used as a supporting liquid, this silver will no longer diffuse into the glass if the contact takes place in an atmosphere containing hydrogen, which prevents the silver from passing through in an ionic state.

In the following, different embodiments of the invention are described in connection with the drawings. Fig. 1 and 2 show a longitudinal section resp. a plan view of a first embodiment. Fig. 3, 4 and 5 show a longitudinal section, resp. a cross-section and a plan view of another embodiment, where the depressions are formed by channels. Fig. 6, 7 and 8 show a longitudinal section, resp. a cross-section and a plan view of a further embodiment where the channels have an angular or roof-shaped course in the transverse direction of the glass path. Fig. 9, 10 and 11 show a longitudinal section, resp. a cross section and a plan view of an embodiment where the cavities are circular. Fig. 12 shows a cross-section through a variant of the embodiment in fig. 9-11, which are used to produce a non-planar track. Fig. 13 shows, on a somewhat larger scale, a cross-section where the edge part of the glass path is seen and where the underside of the glass the path is protected by a gaseous atmosphere. Fig. 14 is a perspective view, partly in section, of an embodiment where the liquid is brought into contact with the underside of the glass web by means of channels that are drilled through the solid underlying support layer, and which have outlets through channels that extend across the direction of movement of the glass web . Fig. 15 shows in perspective and partly in section an embodiment which is analogous to that in fig. 14 showed.

In fig. 1 and 2 you can see the glass path 1 moving in the direction of the arrow f. The glass

rests — with the exception of the edge parts of the glass track, which may be in contact with the cooled part of the solid substrate — on successive projecting parts, 2, 3, 4, hereinafter usually just called projections, which are formed by the surface of liquid contained in cavities in the upper side part

of blocks 5, 6, 7 which consist of refractory material. Through these blocks it can go

channels 8, 9, 10, through which one leads

a heating resp. cooling medium,

depending on the heat treatment to which the glass web is to be subjected.

In fig. 3, 4 and 5, the protrusions that support the glass path are formed by liquid contained in successively arranged channels 12, 13, 14, which are arranged in the upper surface of blocks of the same type as the blocks 5, 6, 7 in the first embodiment. From fig. 5 shows that these channels are rectilinear and extend across the direction of movement of the glass path.

In fig. 6, 7 and 8, the channels 15, 16, 17 are analogous to those in fig. 3, 4 and 5 showed, only with the difference that they have an angular or roof-shaped course in the transverse direction of the track.

In fig. 9, 10 and 11, the channels are replaced with cavities 18 of circular cross-section, which all lie in the same plane. In fig. 12, on the other hand, the refractory substrate 19 has a vaulted surface, much like a road surface, and the circular cavities 18 are arranged in this surface, whereby a continuous glass path 20 with a curved profile can be produced.

In fig. 13, the middle part of the glass path 1 rests on projections 2 of molten metal, which are located in hollows in a block 21 of graphite.

The edge part 22 of the glass track here rests on adjacent parts 23 and 24. The part 23, which consists of graphite or other refractory material, serves as an intermediate part between the graphite part 21 and the support part 24 of steel, which is cooled from the inside by means of a channel 25 through which it circulates water, so that a cooling gradient is achieved in the edge portion 22. At 26, a supply for protective gas is arranged, which from this supply flows through the channels 27, - 28, 29 and prevents the molten metal and the graphite block from coming into contact with air. If this gas is reducing, it also protects the underside of the glass web against otherwise possible reactions with the supporting liquid.

The entire supporting device rests on a brickwork 30, in which pipes 31 are arranged through which heating or cooling medium can be led. The masonry is provided with an external, insulating coating, which also serves to maintain at 28 an atmosphere that protects the graphite block 21.

In the embodiment shown in fig. 14, the support 34 has vertical channels 35 which are arranged along transverse lines; between these lines there are also arranged transverse channels 36, which have a small depth. Supply of liquid under pressure to the upper side of the block takes place continuously through the channels 35, and the liquid flows through the channels 36 and collects in lateral channels 37, which lead the liquid to a container, from which the liquid can be circulated back. In this embodiment, the glass web 1 is supported by the liquid which flows through the channels 35 and which expands under the glass web in front of and behind the aforementioned channel lines, following the arrows f, before it falls into the discharge channels.

In the embodiment shown in fig. 15, the support is formed by transverse elements 34 between which slits 37 are formed. These elements can, as shown, be equipped with channels 38, they then consist of metal or non-porous refractory material. However, they can also consist of porous material, e.g. of porous graphite, and then not contain channels. The supply of liquid takes place either through channels or through pores in porous material, via lines 39. The thin layers or drops formed by the liquid expand on the element 34 and flow to the slits 37 in the direction shown by the arrows F.

Other embodiments are possible. For example, the elements can be placed in the direction of movement of the glass web, care is then taken that the slits 37 are not placed in line with each other, to avoid the risk of deformation of the glass web. The elements 34 can be arranged so that they form a grid; the sides of the grid then extend crookedly in relation to the direction of movement of the glass path.

Incidentally, the support can, instead

to be planar as described above, have any regulated cylindrical shape in the direction of movement of the glass path, e.g. for the production of corrugated glass webs.

Claims (32)

1. Method for supporting a glass web or similar thermoplastic materials, characterized in that the web (1) is supported on several carriers (2, 3, 4) which, at least in the part that is in contact with the glass, consists of a liquid and that the part of the glass web which is located above the zone which is limited by two liquid carriers has no contact with any solid body. 2. Method according to claim 1, characterized in that between the web (1) to be supported and an underlying fixed surface, several liquid-shaped carriers are inserted which protrude above this surface, the edges of the liquid-shaped carrier (2, 3, 4) being made up of curved surfaces as the liquid is practically inactive and does not wet the glass and carry it by the action of the surface tension. 3. Method according to claim 2, characterized in that the floating, projecting support parts (2, 3, 4) are fixed in position on the solid support part (5, 6, 7) by means of anchoring recesses. 4. Method according to claim 2, characterized in that the floating, projecting support parts (2, 3, 4) are fixed in position on the solid support part (5, 6, 7) by means of zones that can be moistened by the relevant liquid. 5. Method according to claim 1, characterized in that the liquid is kept in continuous contact with the lower surface of the glass sheet (1) through several openings in the solid underlying layer to supply between the glass sheet to be supported and the solid carrier a majority of liquid carriers (2 . arranged at the surface of said carrier. 6. Method according to claim 5, characterized in that the fixed, underlying layer (5, 6, 7) is porous. 7. Method according to claim 5, characterized in that the liquid is supplied to channels in the solid, underlying layer (5, 6, 7). 8. Method according to any one of the preceding claims, characterized in that the glass web (1) is in a plastic state and is kept in motion in relation to the floating supports (2, 3, 4). 9. Method according to claim 1, characterized in that the floating supports (2, 3, 4) under the glass plate (1) are kept in motion in such a way that the contact zone between the glass plate and the floating support constantly changes. 10. Method according to claim 1, characterized in that the liquid supports have an extent in the direction of movement of the glass web which is of the same order of magnitude as the shortest supported glass plates (1). 11. Method according to any one of the preceding claims, characterized in that the upwardly projecting liquid supports have, counted in the direction transverse to the direction of movement of the glass web, an extent that is slightly smaller than the width of the glass strip. 12. Method according to claim 2, characterized in that the floating supports form narrow, closely arranged ribs (12, 13, 14) which run across the direction of movement of the glass band. 13. Method according to claim 12, characterized in that the ribs (12, 13, 14) are rectilinear. 14. Method according to claim 12, characterized in that the ribs (15, 16, 17) have the form of angles whose apex lies in the axis of symmetry of the glass band, and which are oriented in the direction of movement of the glass web. 15. Method according to claim 12, characterized in that the ribs have a curved shape, e.g. shape like a circular arc. 16. Method according to claim 12, characterized in that the ribs are divided in their longitudinal direction into a number of separate individual pieces, which possibly extend at an angle to each other. 17. Method according to claim 1, characterized in that the floating supports consist of drops (18), e.g. globular ones, (18). 18. Method according to claim 1, characterized in that the underlying fixed surface (5, 6, 7) slopes downwards in the direction of movement of the glass band, in order to reduce the braking forces exerted on the glass. 19. Method according to claim 1, characterized in that the strange fixed flat slopes upwards in the direction of movement of the glass path, in order to increase the braking forces. 20. Method according to claim 1, characterized in that the underlying solid surface has a cylindrical surface and that the rectilinear liquid supports are placed along boundary lines of this surface, lying essentially horizontally and perpendicularly to the direction of movement of the glass strip. 21. Method according to claim 1, characterized in that to obtain a glass path with a non-straight cross-sectional profile, e.g. to obtain a glass path (20) with a cylindrical or wavy surface, the floating support parts (18) are arranged in the surface part of a solid body (19), the profile of which corresponds to the profile of the glass path one wants to achieve. 22. Method according to claim 21, characterized in that the upwardly projecting liquid parts (18) which form supports comprise depressions or rectilinear channels, which are placed along the cylindrical surface horizontally and parallel to the direction of movement of the glass band. 23. Method according to any one of the preceding claims, characterized in that the support consists of a plurality of elements (5, 6, 7) placed one after the other, each of which is provided with a heating or cooling device (8 , 9, 10), in order to give the glass the desired heat treatment. 24. Method according to any one of the preceding claims, characterized in that by contact with cooling means (23, 24, 25) the edge parts (22) of the glass band are brought to a greater degree of stiffness than the middle part. 25. Method according to one or more of the preceding claims, characterized in that a neutral or reducing gas is introduced under low pressure into the spaces between the floating supports in places where the carrier fluid is exposed to contact with the atmosphere which can have a changing effect on the carrier fluid, which gas can simultaneously inhibit any reaction between the glass and the carrier liquid (26, 27, 28, 29). 26. Method according to claim 25, characterized in that the gas which is brought into contact with the underside of the glass web in particular contains hydrogen. 27. Method according to any one of the preceding claims, characterized by the use of carrier liquids of different nature, over which the glass web is successively passed along its path, where the nature of these liquids may in particular depend on the successive temperatures to which the glass web is exposed. 28. Method according to claim 5, characterized in that the liquid is fed back into the circuit after being cleaned. 29. Method according to packing sand 5 and 28, characterized in that the fixed, underlying layer consists of elements (34) arranged next to each other. 30. Method according to claim 29, characterized in that the elements are placed across the glass path. 31. Method according to claim 29, characterized in that the elements are placed in the longitudinal direction of the glass web, and that the joints (37) between the elements are mutually offset so that they do not lie along continuous lines that run parallel to the direction of movement of the glass web. 32. Method according to claim 29, characterized in that the elements are arranged so that they form a net whose side edges lie at an angle in relation to the direction of movement of the glass path.