METHOD FOR THE PRODUCTION OF CURVED GLAZING

Abstract: The starting material used for the production of curved glazing is a composite pane (1) consisting of a sandwich of at least two flat glass panes (2, 3) and a single or multiple plastic layer (4) positioned between each pair of glass panes. The composite pane is brought into engagement with a curved surface and is then bent at ambient temperature without softening of the plastic layer or layers until the edge sections of the pane engage on the curved surface (5). Finally, retaining means (8) are fitted in order to hold the cold-bent composite pane in the curved position.

Description: Method for the production of curved glazing The invention relates to a method for the production of curved glazing, wherein the starting material used is a composite pane consisting of a sandwich of at least two flat glass panes and a single or multiple plastic layer positioned between each pair of glass panes, which composite pane is brought into engagement with a curved surface and is then bent until the edge sections of the pane engage on the curved surface, and, finally, retaining means are fitted in order to hold the curved composite pane in the curved position. A method of this type is disclosed in EP-A 0 282 -.68. Curved panes fitted m the facade or the roof of a building usually consist of a suitable plastic, such as polycarbonate. This material is easy to bend and has the advantage that it is not able to shatter into pieces, as a result of which injury to passers-by can be avoided. A disadvantage is that the plastic used is a relatively soft material and in the course of time the pane becomes covered with a large number of scratches caused by grains of sand and the like brushing over it. There is a gradual deterioration in clearness and transparency. It is known per se to bend a single glass pane in the cold and to fit it in a curved frame. When fitted in certain locations, such a pane can, in the event of breakage, constitute a risk to persons or objects underneath it. This risk can be counteracted by applying a film to one side, but that side is then once again susceptible to scratching. EP-A 0 282 --68 describes a method for the production of a curved glass panel, wherein a sandwich of two flat glass panes and an mterlayer of a transparent plastomer adhesive is brought to a temperature of between 80 °C and 1--0 °C, sufficient to soften the plastomer adhesive and to permit creep thereof. The sandwich is placed on a cylindπcally curved former and by applying forces is curved in accordance with the shape of the former. A curved edging strip is fitted on the curved ends of the sandwich and a straight edging strip is fitted on the straight edges of the sandwich. The edging strips are joined to form a frame, after which the bending forces are removed and the curved glazing is removed from the former. The principle of this known method is thus bending at elevated temperature at which the mterlayer is softened. This method is expensive and can be carried out only in a factory or workshop and not on the building site itself. The aim of the invention is to overcome this disadvantage and to this end the method indicated in the preamble is characterised in that the composite pane is curved at ambient temperature without softening of the plastic layer or layers. Cold-bending of flat sandwich panes consisting of two glass panes and a plastic film positioned between the glass panes has up to now been regarded as impossible to achieve in practice because there was the preconception that on cold-bending of such panes delamination of the plastic layer would occur as a consequence of the difference in elongation in the surface of the two glass panes at the location of their point of contact with the plastic layer. The merit of the invention is that this preconception has been overcome and that, by means of cold-bending, completely safe, scratch-resistant curved glazing can be fitted for the purposes of, for example, transparent roofs of railway stations. The method according to the invention leads to appreciable savings and to excellent results in practice. Of course, the invention can also be used for glazing in facades, glazing in lift shafts and the like. The method according to the invention is extremely suitable for carrying out on the building site, said curved surface forming part of a frame and said retaining means forming fixing means for fixing the curved composite pane to the frame. A not inappreciable advantage of curved glazing is that the latter has acquired greater rigidity and strength as a result of the curvature. The invention will now be explained in more detail by way of example with reference to the figures. Figure 1 shows a diagrammatic representation of the method according to the invention. Figure 2 shows a cross-section through the glazing in the flat state. Figure 3 shows a side view of curved glazing obtained according to the invention on the roof of, for example, a railway station. It can be seen from Figures 1 and 2 that a flat composite pane 1, consisting of a sandwich of two glass panes 2 and 3 and a single or multiple plastic layer 4 positioned between said glass panes, is brought into engagement symmetrically with a curved surface of a frame 6 and is then subjected to loading close to the ends (see arrows 7) in the direction of the frame. The result can be seen in detail in Figure 3- By means of cold- bending the composite pane has, in the curved position, been brought with its peripheral edge into full engagement with the frame 6, the curved pane being held in place with the aid of fixing means, which are indicated diagrammatically by 8 in Figure 3- Said fixing means can consist, inter alia, of bolts which extend through holes in the glazing and the frame and can also consist of robust glazing beads. For example, the pane 2 has a thickness of 5 mm and the pane 3 a thickness of 3 mm and the thickness of a film made up of two different plastic materials is about 0.75 mm. Various variants of the invention shown are possible within the scope of the claims. For instance, the sandwich can also comprise more than two glass panes, a plastic layer being present between each pair of glass panes. Glazing consisting of more than two glass panes can in general be curved more easily than glazing of the same thickness consisting of two glass panes.

Claims: Claims 1. Method for the production of curved glazing, wherein the starting material used is a composite pane (1) consisting of a sandwich of at least two flat glass panes (2, 3) and a single or multiple plastic layer ( ■ -) positioned between each pair of glass panes, which composite pane is brought into engagement with a curved surface (5) a d is then bent until the edge sections of the pane engage on the curved surface (5)t and, finally, retaining means (8) are fitted in order to hold the curved composite pane in the curved position, characterised in that the composite pane is curved at ambient temperature without softening of the plastic layer or layers. 2. Method according to Claim 1, characterised in that said curved surface (5) forms part of a frame (6) and said retaining means (8) form fixing means for fixing the curved composite pane to the frame. 3. Method according to Claim 1 or 2, characterised in that the glass panes consist of tempered or toughened glass. ■ - . Construction provided with glazing produced in accordance with one of the preceding claims.

Inventors: VAKAR LASZLO IMRE, VAKAR, LASZLO, IMRE
Applicants: HOLLAND RAILCONSULT B V, VAKAR LASZLO IMRE, HOLLAND RAILCONSULT B.V., VAKAR, LASZLO, IMRE
Application year: 1997
Main classification: E06B3
IPC codes: B32B17, C03B23, E04D3, E06B3