IL45035A - Manufacture of glass bodies with bulging portions - Google Patents

Description

Manufacture of glass bodies with bulging portions Andreas Meyer Ltd, Inventor: Andreas Meyer TKB OK'TTJK IK'XOD The present invention concerns the manufacture of glass bodies with bulging portions. One particularly preferred kind of bodies produced in accordance with the invention comprises a vaulted or dome-shaped central portion and a substantially flat, circumferential rim portion. The dome-shaped portion of such bodies is preferably centrosymmetrical with a circular or oval base.

It is also possible in accordance with the invention to produce bodies with several bulging portions separated from each other by substantially flat zones.

The glass bodies produced in accordance with the invention have various applications. For one, they may be decorative objects in themselves. They may also serve as protective covers for various purposes. Another application of importance is their use for the production of convex or concave mirrors by depositing on the bulging portion a reflective surface by any known method. Many other applications are conceivable.

Conventionally the production of shaped glass articles involves casting, blowing, injection moulding and the like operations which forjmany purposes are too complex and expensive. It is further known to produce high precision concave or convex glass structures by grinding, e.g. for the manufacture of concave or convex mirrors. This method, too, is extremely time-consuming and expensive for all those purposes where a, high degree of precision is not required.

It is also known to produce vaulted or dome-shaped glass structures by placing a glass plate on a suitably formed mould and heating the glass to the softening temperature upon end upon softening oag and flow Into the cavit so aa to bear on the Inner walls of the could or on the apex of the convex side no that upon softening it bends and flows so as to come to bear on th¾ outer walls of the mould. In either case, in order to avoid strong adhesion of the glass to the could which would impede the removal of the finished article therefrom, it is customary to line the mould with an inert inorganic separator substance, e.g. pulver owe gypsum. Thle method is applicable only for B ki g relatively shallow domes which form readily by heating the glass to between 600-700°C. At this temperature he glass surface that eventually comes into contact with the separator retains a sufficient degree of toughness to prevent it from becoming roughened by contact with the separator.

On the other hand, the eethod hae turned out to be unsuitable for Baking deep domes. For making such domes higher temperatures are required of the order of 700-800°C and at such temperatures the surface of the bent glass plate so tens to such a degree that it becomes roughened upon contact with the separator.

The present Invention aims at providing a simple, reliable and divereifiable method of making glass articles with bulging portions free of any limitations of the kind set out above.

In accordance with the invention there is provided a method of forming a glass article with at least one bulging portion, comprising placing a flat glass plate within a kiln on a horizontal surface lined with a separator in such a way that any portion of the glass plate designed to bulge is out from bulging, and heating the. kiln so that the glass is heated to at least its softening temperature whereupon any non-retained portions of the glass plate bulge.

Where the glass plate is placed directly on the separator lining, a recess or recesses will be produced in the lining so that any portion of the plate designed for bulging is out of contact with the lining.

Alternatively, the glass plate may be placed on a spacer body or a set of such bodies. Such a spacer body may be of glass and thus become fused to the plate and form part of the finished article.

Where in the above embodiment the spacer body is of glass, another glass plate with at least one hole in it may be interposed between it and the separator lining. In such an event a composite glass body is formed in one single operational step, comprising a flat bottom (lower plate) and a bulging portion (upper plate).

The porous separator material may be a coherent shaped body <3r-Lbe pulverous, and be of any suitable inert substance that does not react with the glass in any way at the glass softening temperature. Examples of such materials are gypsum, various silicates, chalk.

It is believed that during heating of the kiln, hot gases expand through the separator material into the space below the glass plate, presumably by thermal convection- flow, and the ensuing gas pressure causes the softened glass plate to bulge at the non-retained portions. It is thus seen that in accordance with the invention a kind of automatic blowing arrangement is provided.

Due to the fact that in the practice of this "-. :.:"reinvention the glass plate is out of contact with the separator lining, the temperature in the kiln may he raised as required without any danger of the glass becoming roughened. Because of this there is no limitation on the depth and radius of curvature of any bulges produced in the glass plate in accordance with the invention.

The formation of the article is completed by turning the heat off and subjecting the kiln to controlled cooling in a manner known in the art.

The retainer body or bodies, as the case may be, may be of glass. In this case they are fused to the glass plate in the course of the formation process and form(s) part of the finished article. Alternatively, the retainer body(ies) may be of a different material that is not fused to the plate, e.g. stainless steel, to be removed after the completion of the formation of the desired article. In this case it may be necessary or advisable to interpose a separator material between the retainer and glass plate.

Where the retainer body(ies) is or are of glass, the face that bears on the plate may be ornamented in any desired known way, or alternatively, an ornamental flat body may be sandwiched between theretainer and glass plate, and in this way the fihal article can be ornamented.

In accordance with the invention the operation may be designed for any desired number of bulges in the finished article.

In a preferred embodiment of the invention there is produced a centrosymmetrical dome-shaped article with a the dome-shaped portion of such an article may be circular or oval. To produce such an article an annular retainer body is used having a shape corresponding to that of the desired base line of the dome-shaped portion of the article, and the recess in the separator is also shaped accordingly. Here again the retainer body may be either of glass to be fused to the finished article or a foreign body to be removed at the end of the operation. In case of a glass retainer body, ornamentation is possible in the manner specified.

If desired, the dome-shaped glass article produced in accordance with this invention may be fitted with a flat base plate which, again if desired, may be ornamented from within so that the dome-shaped cover serves to protect the ornament. One way of making such a composite structure in accordance with the invention comprises taking a dome-shaped article produced as described above, placing it on a flat glass plate decorated as specified, making at least one hole in the plate to enable the passage of hot gases therethrough, and putting the assembly into a kiln on a horizontal surface lined with a separator whereby the glass plate and the dome-shaped structure are fused together at the edges.

By another way a composite structure of the above kind is produced in one single operational step by placing a first glass plate comprising at least one,hole within a kiln on a horizontal surface lined with a separator layer, placing on this plate an annular glass ring, placing on the ring a second glass plate and on the latter yet another annular ring, and heating the kiln. During the heating the gases that expand from the separator layer penetrate through the hole in the In the above embodiment the uppermost retainer ring may be of glass and thus become fused to the edge of the structure and form part thereof, or alternatively, be a removable ring of a different material, e.g. of stainless steel, and be positioned with the interposition of a separator layer.

Composite glass bodies of this kind may be filled with a transparent or translucent liquid. For this purpose use may be made of the hole in the bottom plate, which is subsequently sealed. Such a liquid filled dome-shaped composite body may serve as lens.

The invention is illustrated, by way of example only, in the accompanying drawings in which: Figs. 1 and 2 are diagrammatic elevational sections of an arrangement for producing a glass article in accordance with one embodiment of the invention; Fig. 3 is a diagrammatic elevational section through an article produced in accordance with the invention and fitted with a bottom plate; Figs. 4 and 5 are diagrammatical elevational sections through an arrangement for making a dome-shaped structure in accordance with the invention with a bottom plate in one single operational step.

As shown in Fig. 1 , the plate 1 of an oven is lined with a separator 2, e.g. of gypsum, comprising a central circular recess 3 with a circumferential shoulder 4. Resting on shoulder 4 is a disc-shaped glass plate 5 held in position by a glass retainer ring 6 covering a rim portion 7 of the plate.

When the overiis heated hot ases ex and throu h the separator lining 2 into the recess 3 and blow up the softened glass plate 5 so that it bulges and assumes a domelike shape as shown in Fig. 2. The rim portion 7 of glass plate 5 is held in position by the annular glass retainer ring 6 which during heating becomes fused to it. The finished article is thus a dome-shaped body with a flat cireumferential, reinforced rim. If desired, the lower face of the retainer ring 6 may be decaated, or alternatively, a decorative flat body may be placed between it and the rim portion 7 so that in the finished article the circumferential, reinforced rim is decorated.

A body of the kind produced in accordance with Figs. 1 and 2 may serve as a cover for various purposes and also for the production of concave or convex mirrors.

Fig. 3 shows how a body produced in accordance with Figs. 1 and 2 is fitted with a flat bottom plate. As shown, the dome-shaped body 8 with its flat, reinforced circumferential rim 9 is placed on a flat glass plate 1 0 resting inside a kiln on a plate 1 1 with interposition of a separator lining 1 2. Glass plate 10 lias a hole 1 3 and, if desired, may comprise a decorative or instructional design 1 4 applied to its upper face in any conventional way. Upon heating the hot gases expand through hole 1 3 into the inner space of the dome-shaped body 8, and keep:: body 8, which softens upon heating to the glass fusion temperature, from collapsing.

In this way the circumferential rim 9 becomes fused to the edge of the circular plate 10 and a composite body is formed comprising a decorated bottom plate 10 and a dome-shaped portion 8. The dome-shaped portion 8 serves as a guard for the way the decoration is preserved. If desired, the heating may be continued for a period of time sufficient to enable dome 8 to blow up further to a predetermined larger size.

In accordance with the embodiment of the invention illustrated in Figs. 4, and 5 a composite body similar to the one described with reference to Fig. 3 is produced in one single operational step. As shown in Fig. 4, a bottom plate 15 comprising a hole 16 rests withiha kiln on a plate 17 with interposition of a separator lining 18. This bottom plate 15 comprises on its upper face a decorative or instructional design 19 which in the finished article should be covered by the dome-shaped portion of the composite body. Above bottom plate 15 rests another glass plate 20 with the interposition of an annular glass ring 21 serving as spacer, and on top of plate 20 there is positioned a retainer ring 22 which in the particular embodiment shown in Figs. 4 and 5 is also of glass but which may also be of any other material that is not fused to glass and is removed when the formation of the body is completed.

Upon heating hot gases from the separator 18 expand through hole 16 into the space between plates 1 and 20 and in consequence thereof and due to the presence of the retainer ring 22 plate 20 is blown up to bulge into a domelike shape as shown in Fig. 5· The retainer ring 22 becomes' fused so as to form part of a composite, reinforced sandwichlike rim portion of the composite body.

The above described method of producing a composite body of the kind specified in one single operational step is-illustrative of the embodiment of the invention where a spacer

Claims (10)

1. A method of forming a glass article with at least one bulging portion, comprising placing a flat glass plate within a kiln on a horizontal surface lined with a separator in such a way that any portion of the glass plate designed to bulge is out of contact with the separator, placing on the glass plate at least one retainer body to prevent selected zones of the plate from bulging, and heating the kiln so that the glass is heated to at least its softening temperature whereupon any non-retained portions of the glass plate bulge.

2. A method according to Claim 1 , wherein the separator lining is recessed so as to ensure that any portion of the glass plate designated to bulge is out of contact with the lining.

3. · A method according to Claim 1 , wherein the glass plate is placed on at least one spacer body so as to ensure that any portion of the glass plate designated to bulge is out of contact with the lining.

4. A method according to any one of Claims 1 to 3» wherein the retainer body is of glass and becomes fused to the finished article.

5. A method according to any one of Claims 1 to 3» wherein the retainer body is of a material that does not removed fuse with glass and is/at the end of the formation operation.

6. A method according to any one of Claims 1, 2, A and 5 for the formation of a dome-shaped glass article with a substantially flat rim portion, wherein a circular or oval recess is produced in the separator lining and an annular retainer, body is employed, the contour of the recess and the shape of the inner edge of the retainer body being made to correspond to the base line of the dome portion.

7. A method according to any one of Claims 1 , 3» 4 and 5 for the formation of a dome-shaped glass article with a substantially flat rim portion, wherein an annular spacer body and an annular retainer body are employed, the inner edges of both of which being made to correspond to the base line of the dome portion,

8. A method for the formation of a dome-shaped glass article with a substantially flat rim portion and comprising a bottom glass plate, which comprises making a dome-shaped glass article according to Claim 6 or 7, placing it on a flat glass plate decorated as specified, making at least one hole in the plate to enable the passage of hot gases therethrough, and putting the assembly in a kiln on a horizontal surface lined with a separator whereby the plate and the dome-shaped structure are fused together at the edges.

9. A method according to Claim 8, wherein heating is continued to enable the dome to blow up to a predetermined larger size.

10. A method for the formation of a dome-shaped glass article with a substantially flat rim portion and having a bottom glass plate, comprising placing a first glass plate with at least one hole within a kiln on a horizontal surface lined 45035/2 12 glass ring, without covering the said hole, placing on the ring a second glass plate and on the latter yet another annular ring, and heating the kiln so that the second glass is heated to at least its soften^ing temperature. 11· A method of making a convex or concave mirror, comprising making a dome-shaped glass article according to Claim 6 or 7 and plating it with a reflective surface in a known manner* 12· A method of making an optical lens, comprising making a composite body by the method of any of Claims 8 to 10, filling the body with a transparent or translucent liquid and sealing the bottom*