PROCESS FOR MANUFACTURING INSULATING GLAZING

Abstract

The invention relates to a process for manufacturing a vacuum insulated glazing wherein the glazing is assembled in a single stage by supplying glass panes, metallic spacers and corner and frame metallic seal elements which are brazed onto adhesion layers previously deposited onto the edge region areas of the glass panes.

Claims

1. A process for manufacturing a vacuum insulating glazing, the process comprising: a) depositing an adhesion layer onto a peripheral zone on one side of each of at least two glass panes; b) supplying the glass panes separated with a set of metallic spacers in a stack alignment as a pane stack; c) assembling the glazing by: c1)supplying and brazing corner metallic seal elements at each corner of the pane stack onto the adhesion layers of each glass pane, c2) supplying multiple frame metallic seal elements on edges of the glass panes between the corner metallic seal elements, and c3) brazing the frame metallic seal elements onto the adhesion layer, thereby obtaining a finished glazing of each glass pane; d) unloading the finished glazing, wherein the glazing comprises the at least two glass panes, the set of metallic spacers located in a void space between the glass panes, and a peripheral seal ensuring a vacuum tightness between the glass pane, the multiple frame metallic elements are supplied so that each frame metallic element overlaps an adjacent frame or corner metallic seal element for a distance no greater than 3.5 mm, and each frame metallic seal element overlaps further the adjacent frame or corner metallic seal element by free dilatation during the brazing for forming the peripheral seal.

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

3. The process according to claim 1, wherein the assembling c) 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 pumped out in order to reach vacuum between the glass panes.

4. The process according to claim 1, wherein each of the corner and frame metallic seal elements independently comprises Cu or a Cu alloy.

5. The process according to claim 1, wherein heat is supplied by the metallic seal elements during the brazing c1).

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

7. The process according to claim 6, wherein the heating lasts for no longer that 5 minutes.

8. The process according to claim 1, wherein the brazing c3) is performed at a temperature of from 200 up to 300° C.

9. The process according to claim 1, wherein the corner and frame metallic seal elements are made from the same metal.

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

11. The process according to claim 1, wherein the glass pane at the base of the pane stack has the greatest dimensions and each glass pane has dimensions lower than the dimensions of the glass pane located directly underneath.

12. The process according to claim 1, wherein a profile of the corner and frame metallic seal elements does not extend outside surface edges of the glass panes.

13. The process according to claim 12, wherein the profile of the corner and frame metallic seal elements are flush with the edges of the glass pane and the glazing.

14. The process according to claim 1, wherein a profile of the corner and frame metallic seal elements extend outside surface edges of the glass panes and enfold borders of the entire pane stack.

15. A glazing, obtained by the process according to claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0060] FIG. 1 illustrates a view in plan of a double glazing obtained according to the process of the invention, with the straight frame metallic elements 11 and the corner metallic elements 10 overlapping each other. Represented are as well the metallic spacers 8.

[0061] FIG. 2 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, the brazing solder 2, the adhesion layer 3 and the void space 4.

[0062] FIG. 3 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. 2.

[0063] FIG. 4 is a section of a double vacuum insulated glazing obtained according to the process of the invention just before and after brazing the frame metal seal element 1 wherein both glass panes have the same dimensions and the metal seal element 1 enfolds the entire stack border. Represented is as well separated brazing solder layers 9 which form the single brazing solder layer 2 after brazing.

[0064] FIG. 5 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 frame metal peripheral seal element 1 is located inside the area delimited by the edges of the glass panes and is flush with those edges

[0065] FIG. 6 illustrates a particular case wherein both glass panes have the same dimensions and the frame metallic seal element 1 is brazed onto the edges of the glass panes.

[0066] FIG. 7 is a section of a double glazing which is a variant of the one of FIG. 5 wherein the frame metallic seal element 1 is as well located inside the area delimited by the edges of the glass panes but is not flush with the edges.

EXAMPLES

[0067] 1. Reference example (not according to the invention)

[0068] According to previous art (description done in the patent application of AGC Glass Europe WO 2011/061208 A1), a double vacuum glazing has been 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 has been chosen for the small pane. A first seal adhesion layer of pure copper has been deposited by metal spraying (HVOF) on whole glasses periphery. The mean thickness of this layer has been 30 μm. The seal adhesion layer width has been 10 mm and the distance of the adhesion layer from the glass edge has been less than 1 mm. A second layer of Sn.sub.60Pb.sub.40 alloy has then been deposited manually on the first copper layer thanks to a soldering iron. The soldering iron temperature range has been maintained between 300° C. and 350° C. and was measured thanks to a type-K thermocouple. The measured thickness of this layer has been 300 μm in average. The measurements have been done randomly with a caliper all along the edges. Despite some thickness non-homogeneities due to the manual operations, the two layers were continuous all around the periphery of both the glass panes. Small metallic spacers (small stainless steel cylinders of 500 μm diameter) have been placed regularly each 5 cm on the largest glass pane. This operation has been performed manually using tweezers. A tinned copper frame and the second glass pane a have then been placed on the largest glass pane, on top of the steel spacers. The copper frame had previously been produced as follows.

[0069] Copper frame assembling: Stamped corner pieces and folded straight pieces have been welded together by laser welding. After welding the junctions of the copper pieces, the obtained squared frame (574 mm * 574 mm) has been tinned (10 μm of tin deposited by electrolysis). The frame obtained has presented a Z-shape section in order to be able joining the metallized areas of the two glass panes (like the one of FIG. 2).

[0070] The whole seal (zone edges of the first pane, the copper frame and zone edges of the second pane) has been placed in the vicinity of a copper induction ring. Eddy currents have been generated during 1 min in the copper frame and have heated the seal up to 300° C. The temperature has been measured thanks to an IR pyrometer placed near one corner of the glazing. During the process, all seal components (the metallized glass panes and the tinned copper frame) have been pressed together and thus maintained in close contact. The SnPb alloy on the glass panes and the tin on the frame have been re-melted during this step and have created a tight brazed seal all around the glazing. The average brazing width has been 5 mm. Due to the relatively high thermal expansion of the copper frame during that process, the measured copper frame dimensions after assembling have been increased of 3 mm in xy directions. In the chosen configuration, the treatment has been 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 were very close to the glass edges. Based on the observed geometry, keeping 20 mm seal 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 not be achievable with this solution). A tube has been then brazed on the seal and has been used to pump out the glazing before closing it off. Before closing off this tube, the seal tightness has been evaluated with helium leak detector. No leakage has been observed. After pumping the glazing and closing off the tube, the evaluated thermal transmittance of the glazing has been 0.5 W/(m.sup.2.K). The evaluation has been 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)

[0071] The glass pane edges have been metallized similarly to the reference example description. Dimensions of the panes were similar as well as the ones of the reference example. According to the invention the copper frame pieces which have been placed on the glass panes before assembling the whole glazing have been made of 4 different pieces per each edge (2 corner frame and 2 straight frames). The junctions of the two straight frames have been located at the middle of each edge. Before induction heating, the pieces have been allowed free to move relatively from each other thanks to the frame overlappings created in the junction areas (pieces were not pre-welded together as done in the reference example). The different frame pieces were thus free to expanse on each edges and to overlap each other further during the assembling process. The frame expansion and effect of the overlapping has been observed with an high speed camera.

[0072] The solution according to the invention has reduced the relative movement occurring between the frame corners and the glass panes. The total frame dimension has been increased by 1 mm only (3 times less than encountered with the reference example). Based on the observed dimensions, the main advantage of the invention is to combine smaller seal width with a larger glazing dimensions. For a targeted glazing dimension, compromise could be done in term of seal width, complexity of process (larger tolerances could be used during the frame positioning) and the number of frame pieces if necessary. For a fixed window frame, a smaller seal width will generally allow a lower thermal transmittance of the window (by minimising thermal losses by conductibility of the glazing edges). In the present example, the measured U-value of the glazing has been found unchanged compared to the reference solution.

3. Example 2 (according to the invention)

[0073] According to the preferred solution, a glazing has been produced with a frame made of four corner pieces of 5 cm * 5 cm and four straight pieces (of about 476 mm length). The corners pieces were maintained in place during the induction heating step (higher pressure was applied on the corner during the heating). The straights pieces have expanded of 2 times 1.5 mm below each side of the corner pieces. Thanks to the relative fixed positions of the corner pieces, the final glazing dimensions were no more impacted during the heating. In this case the seal width has appeared non-dependant of the glazing size (the overlap has performed as a buffer). The overlapping area size has been directly proportional to the glazing dimensions, without impacting the total seal width. Same trials have been successfully done as well with a 12 mm seal width (compared to a 20 mm seal width used for previous examples).