FR2700977A1 - Method of spraying glass particles onto a substrate and device for implementing it - Google Patents

Abstract

The invention is a method of shaping glass, which consists in spraying glass powder heated to high temperature onto a support 3, the powder being heated to a temperature such that the viscosity is between 10<6.6> and 10<3.0> Pa.s, using a gas torch or a plasma torch. The glass powder consists of microspheres (ballotini) having a particle size between 40 and 200 mu m and the support 3 is heated to a temperature for which the difference with the temperature of the sprayed glass is, in absolute value, less than the thermal-shock point of the said glass. The invention also relates to a device for the implementation of this method, which comprises means for delivering the glass 1 and means 2 for heating the sprayed glass, as well as means, consisting of an enclosure 14, for heating the support 3.

Description

The present invention relates to a process for shaping glass. It also relates to a device allowing the implementation of this method.

There are already many traditional methods of shaping glass, used artisanally or industrially. Mention may be made of blowing, molding, extrusion, continuous casting or even floating. All these glassworking processes make it possible to obtain objects of various shapes: hollow glass, such as bottles, table glassware, or flat glass for tiles and others. However, the shapes obtained by these traditional means are limited and all have a certain regularity. Traditional methods do not lend themselves well to the work of the artist; neither do they make it possible to easily obtain, at the artisanal as well as at the industrial level, a wide variety of shapes as well as a variability of thicknesses. More generally, the known glass shaping processes are difficult to adapt to various uses. They are very specific and therefore limited to a specific purpose.

The present invention overcomes these drawbacks of the known methods. It is likely to be used in many applications, craft or industrial, artistic or technical. Thus, the invention makes it possible to easily obtain glass objects having complex geometric shapes that it was impossible or very difficult to achieve with the known methods. The invention also has an application for the coating of existing objects, for technical or artistic purposes. It is also particularly suitable for decoration.

For example, the invention allows the artistic creation of new shapes in glass, with variations in surface, thickness and colors. It thus makes it possible to obtain various surface effects, such as grain, orange peel, smooth material, runs, etc. The invention can also be used industrially, to produce complex shapes in glass. It is for example possible to produce shapes with undercuts or undercuts or very irregular shapes.

It is likely to be used in the field of bottles or table glassware, to produce decorations hitherto not possible in glass. The invention also allows a coating or a protective covering.

The process according to the present invention can be used in all the known fields of glass application: it can be used for the manufacture of flat glass as well as hollow glass, and can be used industrially or by craftsmen.

The present invention provides a glass shaping process consisting in spraying glass powder heated at high temperature onto a support.

According to one embodiment of the method, the glass powder is heated to a temperature which is a function of the glass used, and such that the viscosity is between 10 6.6 and 103.0 Pa.s (107'6 and 104.0 poises), and preferably between 104.0 and 103.0 Pa.s (105 'and 104'
poises).

According to another embodiment of the method, the glass powder is heated by a gas or plasma torch.

In addition, the glass powder has a particle size of between 40 and 200 µm. The glass powder can consist of microbeads.

According to yet another embodiment of the method, the support is heated to a temperature whose difference with the temperature of the projected glass is in absolute value less than the thermal shock point of said glass.

In addition, the support can be made of a refractory material chosen from the group consisting of refractory plaster, foundry sand, refractory ceramic, chamotte, and ceramic fibers.

According to one variant, the support is made of glass or of a vitrifiable material.

According to one embodiment of the method, the support has a surface release layer. The surface release layer may consist of a mixture based on zircon, talc or mica.

According to another embodiment of the method, the glass powder further comprises coloring additives chosen from the group consisting of pigments, metal oxides and enamels.

It also relates to a device comprising means for distributing the glass and means for heating the projected glass.

According to one embodiment of the device of the invention, the means for dispensing the glass comprise a reservoir for glass powder and a device for dispensing an inert gas by positive pressure.

According to another embodiment of the device, the means for heating the projected glass comprise a gas or plasma torch.

In addition, said means for distributing the glass and said means for heating the glass constitute a spray gun.

According to yet another embodiment, the device further comprises means for heating the support. These heating means can consist of an enclosure or a tunnel.

According to yet another embodiment, the device further comprises means ensuring relative movement of the support and of the spray gun.

Other advantages and characteristics of the present invention will become apparent on reading the following description, given by way of example and with reference to the appended figures, which show:
- Figure 1 a first embodiment of a dis
positive according to the invention;
- Figure 2 a second embodiment of a dis
positive according to the invention;
- figure 3 an example of support for the projection
of glass according to the invention;
- figure 4 another example of support for the pro
jection of glass according to the invention.

For the description of the present invention, the word "glass" is used for the sake of simplicity. It is however understood that this word covers both the glass proper and any similar vitrifiable material, such as for example natural silicates or basalt.

FIG. 1 shows a first embodiment of a device according to the invention. The device of FIG. 1 comprises means 1 for distributing glass powder and means 2 for heating the projected glass powder. It also comprises a support 3 onto which the heated glass powder is projected. This support 3 is in the example of Figure 1 consisting of a foundry sand matrix stiffened by a mixture of sodium silicate and carbon dioxide; the method according to the invention is used to produce a vase 4 on the surface of this matrix, by spraying glass. The support 3 is placed on a plate 5, mounted to rotate about an axis 6.

The means 1 for distributing the glass powder comprise a reservoir 7 containing the glass powder 8.

This glass powder has according to the invention a particle size of between 40 and 200 μm. It can be obtained simply by grinding glass. However, according to the invention, use is advantageously made of precisely calibrated glass microspheres, which have a mechanical behavior facilitating the projection and which make it possible to obtain a more homogeneous result. Various additives can be added to the glass powder 8 and, for example, it is possible to choose, in order to color the sprayed glass, to add pigments, metal oxides or enamels. Thus, a blue coloring is obtained by adding cobalt oxide to the glass powder.

The reservoir 7 containing the glass powder 8 is under pressure of an inert gas, for example argon 9. The outlet of the reservoir 7 is connected to a gun 10 for spraying the glass.

The means for heating the sprayed glass powder consist in the embodiment of FIG. 1 by an oxy-acetylene torch. The oxygen and acetylene inlets 11 and 12 are connected to a distributor 13 which is itself connected to the gun 10. Thus, the glass powder, at the outlet of the gun 10, is heated to a temperature which varies in depending on the glass used, and which is such that the viscosity of the projected glass is between 106.6 and 103.0 Pa.s (107'6 and 104.0 poises), and preferably between 104.0 and 103'0 Pa.s (105I0 and 104.0 poises).

According to the invention, the support on which the glass powder is projected, and therefore in the embodiment of FIG. 1, the matrix 3, is heated. The support is preferably heated so as to reach a temperature whose difference with the temperature of the projected glass is in absolute value less than the point of thermal shock of said glass. In a manner known per se, the term thermal shock point is the maximum temperature variation that a given glass can undergo without damage. This thermal shock point is determined experimentally, or can be calculated from the coefficient of linear expansion of the glass in question.

In order to heat the support 3, there is provided in the embodiment of FIG. 1 an enclosure 14 which consists of a circular gas oven, of the type used by master glassmakers, to maintain the parts at temperature during work. blowing. To adapt this oven to the process according to the invention, the plate 5 and its axis 6 have been added thereto. In addition, the oven door has been fitted with a projection window allowing the passage of the gun 10. In the enclosure 14 thus produced, the support 3 is heated to a temperature whose difference with the temperature of the projected glass is in absolute value less than the point of thermal shock of said glass.

After annealing the vessel 4 and its matrix 3, the sand which constitutes the support 3 is removed to release the vessel 4, by mechanical means, by ultrasound, or by chemical means.

The first embodiment of the invention described with reference to FIG. 1 can for example be implemented with soda-lime glass powder, in the form of microspheres with a diameter calibrated between 40 and 200 μm. This soda-lime glass has an expansion coefficient of the order of 101.10 7 m. C 1, and its point of thermal shock, determined by calculation, is worth 99 CC. The glass powder thus projected is heated to a temperature of 889 ° C., so as to have a viscosity of the order of 104 Pa.s (105 poises). A support of foundry sand is used, which is heated to a temperature above 790 "C (889 - 99), and below 988" C (889 + 99).

The first embodiment of the invention shown in Figure 1 is particularly suitable for the production of shapes and hollow glass objects. It makes it possible to obtain complex shapes that cannot be produced by other glass shaping processes. It also makes it possible to modulate the thicknesses of the glass at selected points according to the intentions, or to obtain differentiated surface effects: drips, protuberances ... Thanks to the process, we can color all or part of the object, superimpose or juxtapose colors.

The variation in the projection temperature of the glass makes it possible to obtain different surface effects, such as grain, orange peel, smooth material, or others.

In FIG. 1, only the elements necessary for understanding the invention have of course been shown. Conventionally, after treatment of the parts, a controlled drop in temperature is ensured in a cooling chamber, so as to eliminate, during the cooling of the parts, the internal and surface stresses.

FIG. 2 shows a second embodiment of a device according to the invention. FIG. 2 is a top view in section of the device according to the invention. This comprises a tunnel 20, provided with heating means, not shown, which may for example consist of gas burners arranged at regular intervals. In the tunnel, are arranged means of transport, constituted in the embodiment of Figure 2, a conveyor belt 21. On this conveyor belt, are arranged objects 22, 22 'intended to serve as support for the projection. glass according to the invention. Guns 23, 23 ', of the type described with reference to FIG. 1, are fixed to the walls of the tunnel, and directed towards the supports 22, 22'. Control means, not shown in FIG. 2, regulate the temperature at the various points of the tunnel 20, and control the movement of the conveyor belt 21 and the operation of the guns 23, 23 '.

The operation of the device of FIG. 2 is as follows: it ensures, if necessary, in the tunnel 20 a gradual rise in temperature of the supports 22, 22 ', so that they reach the level of the guns 23, 23' the temperature compatible with the projection already mentioned above.

At the guns 23, 23 ', the supports 22, 22' are partially or totally covered with glass projected by the guns. FIG. 2 only shows a schematic view with two guns. Obviously, it is possible to have a plurality of them, possibly forming several successive projection steps, depending on the nature and / or the quantity of the glass to be projected and / or the configuration of the supports 22, 22 '. After having undergone the glass projection, the objects 22, 22 'continue to move in the tunnel 20, where the temperature gradually decreases to ensure adequate cooling. Where appropriate, the supports 22, 22 'then undergo, in the same tunnel or in a suitable oven, annealing.

The device of FIG. 2 is an example of industrial use of the method according to the invention. For simplicity, there is shown in Figure 2 supports 22, 22 'consisting of bottles and the device of Figure 2 is used to subject these bottles to a surface treatment. In the case of bottles, it is advantageous to provide additional gripping means, intended to hold the neck of the bottles and to make them turn on themselves. The invention then makes it possible to obtain surface effects on bottles which have hitherto been impractical with known means. By relative displacement of the bottles and the guns, one obtains on the bottles the effects of volume, and of thickness, which can vary from one part to another.

It is of course possible to use other supports such as molds. The conveyor belt 21 can be replaced by other devices which make it possible to ensure a relative movement of the parts and of the guns: rack, articulated arm, etc. In addition, in the device of Figure 1, as in that of Figure 2, it is possible to provide means for recovering the glass which is projected by the gun or guns but which is not deposited on the support (s). ). This glass can be deposited on the walls of the enclosure or of the tunnel, on the means of transport of the supports or be sucked up. In the case of a very directed projection, such means of recovery are undoubtedly unnecessary.

FIG. 3 shows an example of a support for the projection of glass according to the invention. FIG. 3 also shows a possible position of a spray gun 30. The support 31 comprises a mold 32, having a surface corresponding to the shape of the part to be obtained.

This mold is covered, at least in the glass projection zone, with a layer 33 facilitating demolding. The glass is projected by the gun 30 and is deposited, forming on the layer 33 the desired object 34. There is no detail here of the means ensuring the relative movement of the support 32 and of the gun 30.

According to the invention, the support 31 can be made of a refractory material, advantageously chosen from the group comprising refractory plaster, foundry sand, refractory ceramic, chamotte or ceramic fibers. Ceramic fibers in some cases provide a repeatedly reusable carrier. For more economical applications, it is possible to choose foundry sands, of the type used in the metallurgical industry. To constitute the support 31, it is possible to produce a model of the shape 34 to be obtained, which is molded with a mixture of foundry sand and a stiffening agent. The fineness of the sand makes it possible to obtain a mold of great precision. One can use as stiffening agent a resin, which is eliminated during the heating of the support before spraying, or a mixture of sodium silicate and carbon dioxide. Refractory plaster or clay of chamotte type provide excellent supports. Finally, as described with reference to FIG. 2, it is possible to use a glass support or more generally a support of the same material as the sprayed glass material. In this case, it is of course necessary that the projected glass and the glass constituting the support be compatible, in particular from the point of view of their coefficient of expansion.

The support 32 can be covered, partially or over the whole of the glass projection zone, with a layer 33 facilitating demolding. This layer can for example be prepared on the basis of Zircon, and facilitates the rapid separation of the sprayed glass and the support. The support 32 can also be covered with a layer 33 improving the surface state of the sprayed glass, and constituted for example based on talc or mica. Advantageously, certain release layers are in the form of a self-leveling coating, which improves the surface condition of the sprayed parts.

FIG. 3 shows a typical example of a support 31, which makes it possible to obtain, thanks to the method according to the invention, parts of a shape hitherto impossible to produce: open parts with a complex surface, with recesses, undercuts, etc. .

Controlling the relative movements of the gun 30 and of the support 31 allows the thickness of the part 34 to be varied from place to place, for example to strengthen or weaken certain areas.

FIG. 4 shows another example of a support for the projection of glass according to the invention. The support of FIG. 4 is typically used to achieve, thanks to the invention, a surface treatment. There is again shown a gun 40, which operates according to a principle similar to that used for the gun described with reference to that of FIG. 1. However, the gun 40 has a plurality of nozzles and allows a more extensive projection, at the same time. way of a brush "brush". The support 41 is made of a refractory material 42, which must undergo on a given zone a surface treatment by spraying glass according to the invention. The material 42 is covered with a mask 43, which delimits the zone 44 to be treated by projection of glass. The gun 40 projects glass onto this area 44 so as to form a layer 45 there. According to the invention, the support 41 is heated before the glass is sprayed and its cooling is then controlled.

The use of the mask 43 makes it possible to produce a projection of glass according to the invention on a precise zone 44, while preserving the rest of the surface of the material 41.

It is therefore easier to understand the various applications that the invention may have for the production of new shapes or for the treatment of surfaces.

Of course, the present invention is not limited to the embodiments described with reference to the figures. In particular, the relative movement of the support and of the gun can be not only a horizontal rotational or translational movement as in Figures 1 and 2, but also a vertical translational movement, a reciprocating movement or a combination of these movements. The means for ensuring this relative movement are not limited to a plate or to a conveyor belt, but can ensure movement of the gun, for example by an articulated arm. Finally, if the principle of the enclosure and the tunnel has been described, it is clear that there are many other means for, if necessary, heating the surface of the support on which the projection is to take place.

Claims (18)

1.- A method of shaping glass, characterized in that it consists in projecting onto a support (3, 22, 31, 41) glass powder heated to high temperature. 2.- Method according to claim 1, characterized in that said glass powder is heated to a temperature depending on the glass used, and such that the viscosity is between 106.6 and 103t Pa.s (lu7.6 and 104t poises ), and preferably between 104.0 and 103.0 Pa.s (105r0 and 104.0 poises). 3. A method according to claim 1 or 2, characterized in that said glass powder is heated by a gas or plasma torch. 4.- Method according to one of claims 1 to 3, characterized in that said glass powder has a particle size between 40 and 200 μm. 5.- Method according to one of claims 1 to 4, characterized in that said glass powder consists of microbeads. 6.- Method according to one of claims 1 to 5, characterized in that the support (3, 22, 31, 41) is heated to a temperature of which the difference with the temperature of the projected glass is in absolute value less than the point thermal shock of said glass. 7.- Method according to one of claims 1 to 6, characterized in that said support (31, 41) consists of a refractory material chosen from the group consisting of refractory plaster, foundry sand, refractory ceramic , chamotte and ceramic fibers. 8.- Method according to one of claims 1 to 7, characterized in that said support (3, 22) is made of glass. 9.- Method according to one of claims 1 to 8, characterized in that said support (31) has a surface release layer (33). 10.- Method according to one of claims 1 to 9, characterized in that said surface release layer (33) consists of a mixture based on zircon, talc or mica. 11. A method according to claim 10, characterized in that said glass powder further comprises coloring additives chosen from the group consisting of pigments, metal oxides and enamels. 12.- Device for implementing the method according to any one of the preceding claims, characterized in that it comprises means for dispensing the glass (1), and heating means (2) of the projected glass. 13.- Device according to claim 12, characterized in that the glass dispensing means (1) comprise a reservoir (7) of glass powder (8) and a device for dispensing by positive pressure an inert gas. 14.- Device according to claim 12 or 13, characterized in that the means for heating the projected glass comprise a gas or plasma torch. 15.- Device according to one of claims 12 to 14, characterized in that said glass distribution means (1) and said glass heating means (2) constitute one or more spray guns (10). 16.- Device according to one of claims 12 to 15, characterized in that it further comprises means for heating the support on which the projection takes place. 17.- Device according to claim 16, characterized in that said support heating means consist of an enclosure (14) or a tunnel (20). 18.- Device according to one of claims 15 to 17, characterized in that it further comprises means (5, 6, 21) ensuring relative movement of the support (s) and of the spray gun (s).