PROCESS FOR MANUFACTURING VACUUM INSULATING GLAZING

Abstract

The invention relates to a process for manufacturing a vacuum insulated glazing wherein the glazing is prepared by supplying glass panes, pillars and edge metallic seal elements, said edge metallic seal elements are brazed simultaneously together and with a functional layer previously deposited onto the peripheral zone of the glass panes.

Claims

1. A process for manufacturing a vacuum insulating glazing, comprising: a) providing a pre-assembly of vacuum insulating glazing components comprising: at least two glass panes each provided with a functional layer on a peripheral zone on at least one of their sides, at least one pillar located between the glass panes and maintaining them at a certain distance from one another and creating a void space between them, and at least two edge metallic seal elements located on the functional layer of the glass panes in the form of a continuous peripheral frame, b) brazing simultaneously together the at least two edge metallic seal elements and the functional layers of the glass panes to form a peripheral seal ensuring vacuum tightness of the glazing, and c) unloading the finished glazing, wherein the edge metallic seal elements are supplied in such a manner that they each overlap the adjacent edge metallic seal element in overlapping areas for a distance no greater than 20 mm and each edge metallic seal element further overlaps the adjacent edge metallic seal element by free dilatation during the brazing for forming the peripheral seal, and wherein at least one edge of the glazing comprises one single overlapping area.

2. The process according to claim 1, wherein the brazing b) is performed in a vacuum chamber.

3. The process according to claim 1, wherein the brazing b) is performed at atmospheric pressure, and the process further comprises soldering at least one closable metallic tube on the peripheral seal through which atmospheric air is then pumped out to reach vacuum between the glass panes.

4. The process according to claim 1, wherein the metal of the edge metallic seal elements is selected from the group consisting of copper and copper based alloys.

5. The process according to claim 1, wherein during the brazing operation, heat is supplied from the edge metallic seal elements.

6. The process according to claim 5, wherein the edge metallic seal elements are heated by induction heating.

7. The process according to claim 6, wherein the whole heating time is no longer than 5 minutes.

8. The process according to claim 1, wherein the brazing operation is performed at a temperature from 150 up to 450 C.

9. The process according to claim 1, wherein all the glass panes have the same dimensions.

10. The process according to claim 1, wherein the glass pane at the base of the stack has the greatest dimensions and the dimensions of each glass pane on top of that base pane are lower than the dimensions of the pane directly adjacent beneath.

11. The process according to claim 1, wherein the edge metallic seal elements do not extend outside the surface edges of the glass panes.

12. The process according to claim 9, wherein the edge metallic seal elements are flush with the edges of the glass pane and the glazing.

13. The process according to claim 1, wherein the edge metallic seal elements extend outside the surface edges of the glass panes and enfold the entire stack borders.

14. Glazing obtained by the process according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0072] FIG. 1 illustrates a view in plan of a double glazing obtained according to a variant of the process of the invention wherein the continuous frame is formed of four edge metallic seal elements (10) having a L-type shape. The edge metallic seal elements (10) overlap each other in overlapping areas (11). Represented as well are the pillars (8).

[0073] FIG. 2 illustrates a view in plan of another double glazing obtained according to a variant of the process of the invention wherein the continuous frame is again formed of four edge metallic seal elements (10) having a L-type shape. The straight portions of the edge metallic seal elements (10) have different relative lengths compared to FIG. 1. Represented as well are the pillars (8) and the overlapping areas (11).

[0074] FIG. 3 illustrates a view in plan of a double glazing obtained according to another variant of the process of the invention wherein the continuous frame is formed of two edge metallic seal elements (10) having a U-type shape. The edge metallic elements (10) overlap each other in overlapping areas (11) located on the longest edges of the glazing. Represented as well are the pillars (8).

[0075] FIG. 4 illustrates a view in plan of another double glazing obtained according to a variant of the process of the invention wherein the continuous frame is again formed of two edge metallic seal elements (10) having a U-type shape. The straight portions of the edge metallic seal elements (10) have different relative lengths compared to FIG. 3. Represented as well are the pillars (8) and the overlapping areas (11).

[0076] FIG. 5 illustrates a view according to section A-A of FIG. 4. It shows an example of suitable shape of the edge metallic seal elements to allow an overlap between the straight portions of adjacent edge metallic seal elements.

[0077] FIG. 6 illustrates a view according to section A-A of FIG. 4. It shows another example of suitable shape of the edge metallic seal elements to allow an overlap between the straight portions of adjacent edge metallic seal elements.

[0078] FIG. 7 shows a section of a double vacuum insulated glazing obtained according to the process of the invention wherein the glass panes (5) have not the same dimensions. Represented are the metal peripheral seal (1), a brazing material (2), the functional layer (3) and the void space (4).

[0079] FIG. 8 shows a section of a triple vacuum insulated glazing obtained according to the process of the invention wherein the glass panes (5) have not the same dimensions and wherein references (1), (2), (3) and (4) have the same meaning as the ones from FIG. 3.

[0080] FIG. 9 is a section of a double vacuum insulated glazing obtained according to the process of the invention just before and after brazing the edge metallic seal elements (10) to form the peripheral seal (1) wherein both glass panes have the same dimensions and the edge metallic seal elements (10) enfold the entire stack border. Represented as well is the functional layer (3) and brazing material (2) before and after brazing.

[0081] FIG. 10 is a section of a double vacuum insulated glazing obtained according to the process of the invention wherein both glass panes have the same dimensions and the peripheral seal (1) is located inside the area delimited by the edges of the glass panes and is flush with those edges.

[0082] FIG. 11 illustrates a particular case wherein both glass panes have the same dimensions and the peripheral seal (1) is brazed onto the lateral edges of the glass panes.

[0083] FIG. 12 is a section of a double glazing which is a variant of the one of FIG. 6 wherein the peripheral seal (1) is as well located inside the area delimited by the edges of the glass panes but is not flush with the edges.

EXAMPLES

1. Reference Example (Not According to the Invention)

[0084] According to previous art (description done in the patent application of AGC Glass Europe WO 2011/061208 A1), a double vacuum glazing is processed with two different dimensions of 6 mm thick glass panes (572 mm*572 mm and 594 mm*594 mm). In order to reach low U-value (below 0.6 W/(m.sup.2.K)), a low-emissivity coated glass is chosen for the small pane. A functional layer made of an adhesion layer and a brazing layer is applied. A first adhesion layer of pure copper is deposited by metal spraying (HVOF) on whole glasses periphery. The mean thickness of this layer is 30 m. The adhesion layer width is 10 mm and the distance of the adhesion layer from the glass edge is less than 1 mm. A brazing layer of Sn.sub.60Pb.sub.40 alloy is then deposited manually on the first copper layer thanks to a soldering iron. The soldering iron temperature range is maintained between 300 C. and 350 C. and is measured thanks to a type-K thermocouple. The measured thickness of this layer is 300 m in average. The measurements are done randomly with a caliper all along the edges. Despite some thickness non-homogeneities due to the manual operations, the two layers are continuous all around the periphery of both the glass panes. Small metallic pillars (small stainless steel cylinders of 500 m diameter) are placed regularly each 5 cm on the largest glass pane. This operation is performed manually using tweezers. A tinned copper frame and the second glass pane are then placed on the largest glass pane, on top of the steel pillars. The copper frame had previously been produced as follows.

[0085] Copper frame assembling: Stamped corner pieces and folded straight pieces are welded together by laser welding. After welding the junctions of the copper pieces, the obtained squared frame (574 mm*574 mm) is tinned (10 m of tin deposited by electrolysis). The frame obtained has a Z-shape section in order to be able joining the functional layers of the two glass panes (like the one of FIG. 7).

[0086] Brazing is performed by induction. The whole seal (zone edges of the first pane, the copper frame and zone edges of the second pane) are placed in the vicinity of a copper induction ring. Eddy currents are generated during 1 min in the copper frame and they heat the seal up to 300 C. The temperature is measured thanks to an IR pyrometer placed near one corner of the glazing. During the process, all seal components (the functional layers and the tinned copper frame) are pressed together and thus maintained in close contact. The SnPb alloy on the glass panes and the tin on the frame are re-melted during this step and create a tight brazed seal all around the glazing. The average brazing width is 5 mm. Due to the relatively high thermal expansion of the copper frame during that process, the measured copper frame dimensions after assembling has increased of 3 mm in xy directions. In the chosen configuration, the treatment was large enough on glass periphery to guaranty a tight seal join. It is of course mandatory that a sufficient part of the frame (5 mm) stays located on the tinned glass edges during and after the heating. Generally, the seal width has to be lower or equal to 20 mm in order to integrate it in a commercial window frame. In this case, due to process tolerances and thermal expansion encountered by the frame, some part of it are very close to the glass edges. Based on the observed geometry, keeping 20 mm seal width will not be possible for large glazing dimensions (for a 3 m length dimension, the copper frame expansion will be of 15 mm and will thus expand beyond the tinned glass edges). A tube is then brazed on the seal and is used to pump out the glazing before closing it off. Before closing off this tube, the seal tightness is evaluated with helium leak detector. No leakage is observed. After pumping the glazing and closing off the tube, the evaluated thermal transmittance of the glazing is 0.5 W/(m.sup.2.K). The evaluation is done based on the method described in the EN674 standard (Glass in building.Determination of thermal transmittance (U value)).

2. Example 1 (According to the Invention)

[0087] Similarly to the reference example description, an adhesion and a brazing layers are applied on the glass panes. Dimensions of the panes are similar to the ones of the reference example. According to the invention, the edge metallic seal elements which are placed on the glass panes before assembling the whole glazing are made of 4 copper pieces (according to the FIG. 2). The overlapping areas of the four elements are located at the middle of each glass pane edge. Brazing is performed by induction using Eddy currents as described in the reference example. During induction heating, the edge metallic seal elements are free to move relatively to each other thanks to the overlapping areas (pieces were not pre-welded together as done in the reference example). The different edge metallic seal elements are thus free to expand on each edge and to overlap each other further during the assembling process. The frame expansion and effect of the overlapping is observed with an high speed camera. The total frame dimension is increased by 1 mm only (3 times less than encountered with the reference example). The main advantage of the invention is to combine smaller seal width with larger glazing dimensions. For a targeted glazing dimension, the process according to the invention allows reducing the peripheral seal width and/or reducing the complexity of the process (larger tolerances could be used during the frame positioning, the number of frame pieces). In the present example, the measured U-value of the glazing is unchanged compared to the reference example. For a given window frame, a smaller seal width will generally lead to a lower thermal transmittance of the window (by minimising thermal losses by conductibility of the glazing edges).

3. Example 2 (According to the Invention)

[0088] A rectangular glazing (dimensions 300 mm by 600 mm) is produced with two edge metallic seal elements presenting a U-shape. The two overlapping areas are located on the longest edges of the glazing, i.e. the 600 mm edges (according to FIG. 3). Brazing is again performed by induction using Eddy currents as previously described. A higher pressure is applied on the corner areas of the edge metallic seal elements during induction heating. Each edge metallic seal elements expands of 1.5 mm at each overlapping area so that the total overlapping length is increased by 3 mm at each overlapping area (2 edge metallic seal elements expand each of 1.5 mm at each overlapping area). The overlapping areas absorb these dilatations and thanks to the relative fixed positions of the corner areas, the final frame dimension on the longest edges of the glazing (i.e. 600 mm edges of the glazing) is no more impacted. Even if the dilatation of the edge metallic seal elements is important (proportional to the glazing dimensions), it is absorbed in the overlapping areas and it does not impact the peripheral seal width. Same trial is successfully done on 300 mm by 600 mm glazing with a narrower peripheral seal width of 12 mm (compared to a 20 mm seal width used for previous examples).