GB2077833A - Spacers for double glazing - Google Patents

Abstract

A spacer bar for a double glazing unit which runs around the edges of the two panes and keeps them apart is made as a hollow rolled metal section containing a desiccant 8 and having openings 10 in its inside face 2, the seam or joint 6 is in the side wall or (preferably) the outside face, and is sealed from atmosphere by a mastic sealant 7. The joint may be plain or joggled lap joint or a lock seam or even a plain butt joint. The openings 10 can be made by a toothed wheel, which may form barbs on the inside of the section. <IMAGE>

Description

SPECIFICATION Spacers for double glazing This invention relates to spacers for double glazing, that is, spacers which are inserted between two panes of glass, extending around the entire periphery of the glass and sealed to both panes to form an air-tight double glazing structure.

It is known to form such a spacer as a hollow section, usually in light alloy, and to insert a desiccant, such as granules of silica gel, inside the section. Small holes or slits in that face of the section which is towards the interior of the structure put that interior space in communication with the desiccant in the hollow section, thereby keeping the space between the panes dry and free from misting.

Numerous such spacers are known, mostly in the form of rolled sections, formed by cold rolling from light alloy strip, with a butt joint or a lap joint placed at the inside face, i.e. the face which is towards the space between the panes. Examples of this type of spacer are shown in European Patent Specification 0 003 715 and in British 1419875 and 1 515 312. In many cases this butt joint forms the narrow path for communication between that space and the desiccant within the section. However, it is of uncertain width and there is a danger of insufficient communication, or alternatively of the gap opening up (especially at the corners of the structure, where L-shaped corner pieces are forced into the ends of the adjacent lengths) so that particles of the desiccant pass into the space between the panes.It is therefore known to provide a lap joint or lock seam joint, and a separately formed line of holes. However the joint, being non-airtight, has always been on that inside face.

A drawback of the rolled section is its weakness during handling, and furthermore the presence of the joint detracts from the appearance of the inside face, visible in the finished structure.

It is also known to use a seamless extruded hollow section. The communicating holes are formed by a spiked wheel or a slit cutter. The extruded section has the advantage of a smooth appearance on the inside face, free from seams and also it is stiffer than a rolled section, but it is substantially more expensive.

According to the invention, it is possible to combine the low cost of the rolled section with the attractive inside appearance of the extruded section by employing a rolled section that has the seam on it outside face, or at least not on its inside face. Hitherto this had been assumed in the trade to be impossible, since the seam is not air-tight and consequently would appear to give access for outside air to the desiccant within the section.

However we have found in practice that it is possible to ensure that the mastic sealant used to secure the spacer bar to the glass coats the exposed outside surface of the bar and seals it against any penetration of air.

We must, of course provide access from the interior of the space between the panes to the interior of the section. This may be done by a line of holes or slits in a known manner but preferably, according to å further feature of the invention, the holes are formed by a special piercing operation that leaves tongues or lugs partly obstructing the insides of the holes. These help to prevent the escape of the small particles of the desiccant from the interior of the section into the space between the panes, even when the structure is subjected to shock, for example during handling and shipping.

Also the tongues form useful barbs that help to retain the legs of the L-shaped joining pieces of plastics material that are forced into the ends of adjacent lengths of bar at the corners of the structure.

According to a further feature of the invention one or both sides of the spacer may be pre-coated with a pressure-sensitive adhesive which is coated with a protective layer. The spacer bar can be marketed in this form and then the manufacturer of the glazing units only has to peel off the strip and place the spacer in contact with the glass.

The granules of desiccant may be incorporated in the spacer in a continuous process as it is being rolled. In a further development the desiccant could be in the form of a cord, or even a foam, making it easier to incorporate on a continuous basis. The resultant bar may then be hermetically sealed in a protective film to prevent the degradation of the desiccant during handling up to the time when it is incorporated in a double glazing unit.

The bar may be mitred at the appropriate intervals in a known manner by a machine which cuts a 90C Vee groove through the greater part of the section but leaves the outer wall intact, so that the bar can be sold in straight pre-mitred lengths, sealed by a protective film, and then folded up to form a rectangular frame by the actual maker of the double glazing units.

Two examples of sections according to the invention are illustrated in the accompanying drawings, in which: Figure 1 is a transverse section through a portion of a double-glazing unit incorporating one form of spacer bar according to the invention; Figure 2 is a view of the spacer bar alone, looking in the direction of the arrow Z in Figure 1 Figure 3 is a section, to a larger scale, on the line Y-Y in Figure 2; Figure 4 shows a typical corner joint between adjacent lengths of the spacer bar; and Figure 5 is a view similar to Figure 1, showing an alternative form of section.

Referring first to Figure 1, a cold-rolled section 1 of aluminium alloy strip has a flat unseamed inside face 2 facing towards the space 3 between the panes of glass, the usual shoulders 5, and a joggled lap joint 6 at its outside face. When the glazing structure is assembled, the mastic sealant 7 used to secure the panes of glass to the sides of the section not only fills the shoulders 5 but also coats and hermetically seals the joint 6 in the outside face, so that the outside atmosphere has no access to the desiccant 8 contained within the section. As will be seen, the sides 9 of the section 1 are slightly concave, so as to hold an adequate quantity of the mastic or other adhesive.

The inside face 2 has a line of perforations (see Figure 2) in the form of slots 1 0. In a typical example they may be 1.5 mm long and spaced at 6 mm pitch. They are formed in a continuous operation by a toothed or spiked roller that pierces the metal and forms a tongue or lug 11 (see Figure 3) on the inside, with the advantages mentioned earlier.

The fact that the seam or joint 6 is on the outside not only improves the appearance of the visible inside face 2, as compared with known rolled sections, but furthermore means that the cross-sectional area of the path of flow for air between the space 3 between the panes and the desiccant 8 within the section is determined solely by the specially formed slots 10, and so can be accurately controlled to have a required known value, which will not change. As indicated earlier, instead of the joint being a lap joint, joggled or not, it could be a plain butt joint or even a full lock seam joint. The latter gives the advantage of added strength and rigidity whereas a plain butt joint, although acceptable within the scope of the invention, is much less desirable.

Moreover, instead of being in the outside face, the joint could be in one of the shoulders 5 or side faces 9, as long as it is not in the inside face 2.

However, the outside face is preferred, for reasons of symmetry and ease of manufacture.

The spacer bar may be produced in indefinite lengths in a cold-roll-forming machinery, starting from flat aluminium alloy strip. As indicated earlier, the desiccant can be introduced into the section during this process, before the joint 6 is closed. The bar may then be cut into lengths and can then pass straight to packing machinery in which it is sealed in a moisture-proof protective film or the protective film may be applied after the last forming stage, before or after the cutting stage. Between the cutting-to-length and the sealing steps it can be mitred at pre-determined points by a machine which cuts only part of the way through the section, so that the outer wall is left intact. This allows the bar to be shipped in convenient straight form to the point where it is folded up to form a rectangular frame and then sealed between two panes of glass to form a glazing unit.

Figure 4 shows how corners may be formed where the sides are formed as separate straight lengths with mitred ends. An L-shaped moulded plastics corner piece 12 has its legs forced into the adjacent ends of the two lengths of spacer bar, and these legs are provided with lugs or teeth 1 3 shaped to resist withdrawal. Further resistance to withdrawal is provided by the tongues or barbs 11 (see Figure 2) resulting from the formation of the slots 10. The mastic sealant, that is applied as the rectangular frame of spacer bars is fitted to the panes of glass, seals the mitred corner joint and prevents moisture from the atmosphere reaching the interior of the section.

Figure 5 shows an alternative form of spacer bar 1' which incorporates a pressure-sensitive contact adhesive on both side faces. The sides, shown at 9' are flat instead of being concave and each has a layer of adhesive 14 covered by a detachable protective strip 15. The strip 15 is peeled off immediately before the spacer bar is applied to the panes of glass. This allows for quick and clean assembly of the double glazing units by relatively unskilled labour; a mastic sealant is still, however applied to the outside of the unit to fill the shoulders 5 and seal the joint. In the section shown in Figure 5 the narrowness of the section dictates the use of a plain lap joint 6' with no joggle.

Claims (12)

1. A hollow rolled metal section made from strip and having four faces and designed for use as a spacer bar in a double glazing structure, in which one of the faces, intended to face inwards in the assembled structure, contains a line of separately formed holes affording communication with the interior of the section and a joint between the edges of the strip forming the section is positioned in one of the other faces.

2. A section according to Claim 1 in which the joint is in that face which is opposite the face having the holes.

3. A section according to Claim 1 or Claim 2 in which the joint is a butt joint.

4. A section according to any one of Claims 1 to 3 which contains a desiccant and is sealed against the ingress of air.

5. A section according to any one of Claims 1 to 4 in which 900 Vee mitres are cut at predetermined intervals in the length of the section, each mitre extending through the wall containing the line of holes and the walls adjacent to this wall, but not the opposite wall.

6. A section according to any one of Claims 1 to 5 including a coating of pressure-sensitive impact adhesive on one or both of the faces adjacent to the face that has the line of holes, the adhesive being covered with a protective coating capable of being peeled off.

7. A section according to any one of Claims 1 to 6 in which the joint is a lap joint.

8. A section according to any one of Claims 1 to 6 in which the joint is a lock seam joint.

9. A section according to any one of Claims 1 to 8 in which the holes are formed in such a way as to leave a tongue projecting inside the hollow section.

10. A double glazing structure comprising a pair of panes of glass spaced apart by a peripherally extending spacer bar of the form according to any one of Claims 1 to 8, side faces of the bar being caused to adhere to the respective panes and the exposed face of the bar being sealed by a mastic sealant.

1 A double glazing unit comprising a pair of panes of glass spaced apart around their peripheries by a spacer formed by a hollow roll formed section having its joint in that face which is exposed in an outward direction and having a line of pre-formed holes in that face which is towards the interior space between the panes, the section containing a desiccant, and the exposed face of the section containing a desiccant, and the exposed face of the section being coated with a mastic sealant that seals the joint.

12. A double glazing unit incorporating spacer bars substantially as described with reference to the accompanying drawings.