Improvements in or relating to tempering glass.

The present invention essentially relates to the air quenching, optionally associated with the bending of glass sheets and more particularly a coating to a frame for holding the glass plates during their temper, their bending and their transportation optionally.

One of the techniques known to bending and tempering air to glass plates uses a frame, a curved profile, open at its center, on which rest the glass plates to be bent, tempered, transported, etc .. . such frameworks are for example described in the patent application published in FRANCE under No. FR-A-2572388.

A glass plate heated to its bending temperature and tempering is deposited on such a framework and it can undergo a bending by simple effect of gravity and / or by pressing, then it can always be transported rests on the framework, especially to quench station where it is subjected to intense blow. One can use a single frame from one workstation to another, but you can also use a plurality of frames each speaker in a defined position, the glass plates thus changing support means when they go to one position to another. The plurality of frames can in some cases be required by a particular organization of tasks, but often it is also necessitated by the inability of a single framework for all the roles: bending frame, tempering frame, transport frame, etc ... in fact, to take all these roles part must possess many qualities hardly compatible: it must keep to high temperatures, have good mechanical strength to withstand bending operations particularly by pressing, it must also have poor thermal conduction to not thermally mark the glass, even the burst when green frame are too different temperatures from each other, it should also possess high porosity to air for not constitute a vis-a-vis the glass screen, air which is blown during quenching.

For this, different types of frames have been tried, but none has given complete satisfaction or could be used in a somewhat broader area than that for which it was designed strictly (limited forms of curves, time glass touch / limited framework does not allow for bending long time for deep or complex shapes to give to drink, or not allowing pressing, etc ...).

Thus, it is conventional to coat a metal frame by a fine mesh, such as bronze; we obtain the porosity and strength desired, but the deformability of the lattice is not sufficient to perfectly fit some complicated forms of one hand frames and thermal insulation brings the mesh is not sufficient to allow time to touch green / frame too long.

To try to increase this insulation was replaced by the metal mesh of the green or ceramic fabric, but a problem of durability, of effritage tissue arises.

Were then available perforated or equipped with projecting fingers metal frames of small dimensions on which the green, or grooves drawn in the frame thickness of the metal, thus reserving under the green passageways for the quenching air. Usually such frames finger or grooved or perforated work if the time to touch green / frame is short; but if the time is extended particularly due to a pressing or because the forms we want to give to the glass are complex and require a forming time a little longer, there is glass breakage.

In the same vein, patent application FR-A-2597089 proposes instead of wire mesh, perforated metal band having a porosity to air of at least about 40%. Such metal perforated strip is difficult to implement, difficult to perfectly fit on complex shaped frames, its porosity is too low if it is to retain sufficient mechanical strength and thermal insulation it is introduced not enough.

Furthermore, it is known from US-A-3,741,743 a metal coating consisting of a fabric formed of metal son whose diameter is between 72 and 152 microns or the superimposition of a first thread - said net " heavy "- whose son has a diameter between 254 and 762 microns, and a second said net net" light "whose son has a diameter of between 38 and 152 microns. To achieve this type of fabric, the son are used as such in the form of monofilaments and are gathered into strands. Thereby the conductivity of the tissue is relatively high and secondly, the porosity is limited and low flexibility.

The present invention aims to provide a cover having qualities of mechanical resistance, thermal insulation, air porosity, resistance to high-temperature deformability which allow its use as a covering support contact means, transporting the green, especially during its bending and / or its air quenching.

It proposes to do an essentially metallic covering intended to be inserted between hot green in objects, in particular green sheets brought to their bending temperature and tempering and their support, in particular essentially metallic, said coating comprising a metal fabric and being characterized in that the metallic fabric is formed of rovings constituted of a plurality of at least approximately 90 elementary son of a diameter less than 50 microns, organized together to form stitches having a thermal conductivity less than 3 and preferably less than 0,2.WM⁻¹.K⁻¹.

In a first embodiment, this coating is an essentially metal fabric formed of rovings of a plurality of elementary son, the wicks arranged in different directions and together stitches and interfering to form knots at the tops of the meshes through which said stitches are dimensionally stable.

In a second embodiment, the coating consists of a metal fabric itself and an intermediate ceramic layer of the zirconium oxide type deposited under the metal fabric.

The invention will now be described in more detail with reference to the appended figures which represent:<ul><li>* 1: a schematic view of a fabric according to the invention and corresponding to the first embodiment,</li><li>* 2: a schematic view of the fabric according to Figure 1 a coating under bending, toughening and / or transportation of the glass plates.</li></ul>

Figure 1 shows an example of fabric 1 having the necessary characteristics for a frame or a coating of green support frame, intervening in bending, to the quenching air and / or during transport, namely:<ul><li>resistance to high temperatures,</li><li>mechanical resistance,</li><li>insulation,</li><li>air porosity,</li><li>deformability to adapt to all profiles of executives.</li></ul>

Until now, the term green frame carrier or carrier medium was used, suggesting that this framework or the support means is arranged below the green. In fact, the invention is to extend to any part or engaging means with the glass, either from above or below the word and the support must be taken in this more general sense.

This fabric 1 is based essentially metal son of refractory stainless steel type to provide, through the metal, mechanical strength and resistance to high temperatures.

In this first embodiment, insulation and air porosity are made by the fineness of the elementary tissue son and their assembly method.

Elementary son used are thin, with a diameter less than 50 microns, especially less than 30 microns and preferably less than 15 microns, for example of the order of 10 microns. This slimming son participates in the ability of the fabric to deform to fit the profile of managers.

A plurality of such son at least about 90, is arranged in strands 2 and 3. By way of nonlimiting example, the wick 2 shown horizontally in Figure 1 is composed of several strands e.g. two strands 4 and 5, each strand itself being comprised of one or several sets of elementary son, for example three sets of 90 each elementary son.

The other wick 3 arranged vertically in Figure 1 is as shown by way of example, formed of several strands e.g. three strands 6, 7 and 8 themselves formed of several sets of elementary son for example two sets of 90 son elementary. This other wick 3 is tied on its entire length and interfere particularly with the wick 2 arranged in another direction to form stitches 10 having at their tops node 11 connecting the wick 2 and the wick 3.

With these knots 11 at their tops, mesh 10 are dimensionally stable.

The sample showed tissue Figure 1 shows approximately square mesh of about 5 mm square and has a thickness of about 0.5 to 2 mm thick.

Advantageously, for increasing the mechanical strength of this tissue and in particular the dimensional stability of its meshes, the strands 4, 5, 6, 7 and 8 do not belong only to a wick 2 or 3, but in length they belong successively to a wick and of the other. They form a series of adjacent loops, partially covering the loops of another series of adjacent loops arranged next to the first series and in opposite directions, these loops being knotted by fours and an additional strand example vertical willing between adjacent loops of each series, with a horizontal strand by example.

Thus each loop part on a portion of its length forming a wick for example 3 and then the formation of another wick by Example 2 and then forming a region type of wick 3 from the previous.

Other weaving patterns are also possible.

The air porosity of such a fabric is at least about 60% and preferably of the order of at least 80%. The meshes may be quadrilateral for example square, of side ranging from 2 to 10 mm.

Other shapes are also possible, in particular manufactured with a number of locks that can be greater than 2; the surface of the mesh remaining however always of the same order, that is to say between approximately 4 mm² and 1 cm².

Such a fabric has a thermal conductivity less than 3 and preferably less than 0.2 WM⁻¹.K⁻¹, which corresponds to a thermal resistance lying between 10⁻³ and 50.10⁻³M².KW⁻¹.

Such a fabric is used to coat a particular frame 20 of toughening and / or bending and / or transportation as shown in Figure 2, this framework is essentially metallic or metallic.

To allow this fabric 1 to be crossed by the quenching air, it is important that the quenching air is not stopped by the frame 20 itself. This frame 20 is then perforated, for example consisting of a flat iron 21 pierced by orifices such as 22 as shown in Figure 2, or formed in an equivalent manner, for example formed of a profile on which are fixed spaced fingers for raise the glass and between which can circulate air, or a profile in which are plotted striations or grooves to allow air or a profiled serrated edge, these various other embodiments not being shown .

In another embodiment, the coating consists of a fabric identical to that described above and by an intermediate insulating layer, for example made of ceramic zirconium oxide type.

The zirconium oxide is for example deposited on the support intended to come into contact with the glass powder by spraying into a flame, plasma or equivalent.

This support being coated with the insulating intermediate layer, it is covered with an essentially metallic fabric. Advantageously to favor the adhesion of the intermediate layer to the frame and improve its mechanical strength especially at high temperature, an undercoat intermediate coefficient of expansion between that of the frame and that of the zirconium oxide layer is provided by example a sublayer based on Ni and Cr.

tempering frames, bending, transport of glass plates may also be covered as described in this second embodiment.

With such coatings, executives can carry the drink throughout their multiple heat treatments if desired, without the need to make changes to part of each treatment.

Such coatings can also be used as electromagnetic shields, as contact materials between any warm body and a support, as do gay rollers for transporting hot glass plates, such as conveyor belt or carpet covering conveyor for supporting hot glass objects.