GB1603092A

GB1603092A - Window frames

Info

Publication number: GB1603092A
Application number: GB1924477A
Authority: GB
Original assignee: BKL Extrusions Ltd
Current assignee: BKL Extrusions Ltd
Priority date: 1978-05-05
Filing date: 1978-05-05
Publication date: 1981-11-18

Description

(54) IMPROVEMENTS RELATING TO WINDOW FRAMES (71) We, BKL EXTRUSIONS LI MITED, a British Company of Birmingham Factory Centre, Kings Norton, Birmingham B30 3HF, do hereby declare the invention for which we pray that a Patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to the construction, design and composition of frames for windows, doors, or vents, and particularly to metal frames. It is very well known that the thermal conductivity of metal frames creates serious problems due to transfer of heat between the internal and external faces of the e.g. window frame. One particular problem is the excessive condensation which occurs on the inside of a metal frame when the atmospheric temperature is low. Metal frames also suffer from various other practical problems, and in particular the external surfaces may deteriorate and may require painting or other maintenance, and condensation occurs internally.

Accordingly it is an object of the invention to provide an improved frame for windows, doors, or vents, which will meet some of the practical problems experienced, and broadly stated the invention consists in a frame for a window door or vent, including a metallic frame member having a separately formed insulating strip of a foamed self-skinned plastics material attached to the metal frame member on a surface thereof which would otherwise be exposed when the window, door or vent is closed, substantially to cover said surface.

In some cases the exposed surface is the external face, but in many applications it may be more convenient to treat the exposed interior face.

According to a preferred feature of the invention the insulating strip is formed with one or more grooves, keyways, ribs or slots to engage, interkey or interlock with corresponding formations on the frame member.

Alternatively, or in addition, the insulating strip may be bonded to the frame member or attached by an adhesive.

In a particular preferred construction the insulating strip is provided with means to support a sealing strip to engage a relatively movable frame (which may be fixed), and in any case the strip preferably engages or lies in close proximity to the outer edge or face of a glazing panel fitted in the frame.

Preferably the insulating material only covers the exposed external surfaces of the frame.

The invention is particularly applicable to opening casement windows having fixed and movable frames, in which case it is convenient that both frames should be formed as defined above, and indeed both frames may be practically identical in construction.

The invention may be performed in various ways and some embodiments will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a somewhat diagrammatic cross-section through the fixed and movable frames of an opening casement window, according to the invention, Figure 2 is a similar cross-section through another embodiment in which the fixed frame is formed almost entirely of plastics material, Figure 3 is another vertical cross-section through the transom and part of the moving vent of a window frame having a lower fixed glazing panel and an upper opening vent, and Figure 4 is another cross-section through a further example housing insulating strips applied to the interior faces of the frames.

In the first illustrated example, the fixed frame of a casement window is illustrated at 10 and the moving opening frame at 11. The opening frames includes a main metal frame member 12, which may be an extruded aluminium section having a main web with an outer flange 13 carrying ribs 14 to support and locate one edge of a bead 15 which itself locates a double glazing panel 16. The inner end of the main web 12 is provided with a further flange 17 having a locating formation 18 for the other edge of the glazing bead 15 which holds the glazing panel in position.

Mounted on and rigidly attached to the external flange 13 of the metal frame is an insulating strip 20 which extends around all four sides of the frame and provides a complete insulating cover. This strip is formed of a foamed polystyrene material with a self-skin and is conveniently extruded to the required cross-section in long lengths and cut to size as required. The insulating strip has a groove 21 to locate and fit over the outer flange 13 of the metal frame, and the flanks of this groove fit over the sloping edges of the flange 13. A suitable adhesive or bonding material is introduced between the insulating strip and the metal frame to anchor the strip in position. The inner edge 22 of the insulating strip lies closely adjacent to the edge of the glazing panel 16, and a further mastic or other sealing substance 23 is introduced into the gap between these two parts. Alternatively, the insulating strip 20 itself may be formed to engage directly against the surface of the glazing panel. This improves the thermal insulation of the whole construction, since in practice it is found that heat transfer through the glazing panel normally occurs largely around the extreme edge of the panel where it lies adjacent to the metal frame. By covering this surrounding edge of the glazing by the foamed insulating strip 20, the heat transfer is materially reduced.

The foamed insulating strip is also provided with a further undercut groove 25 to receive a flexible sealing strip 26, which engages against a corresponding foamed insulating strip 27 of the fixed frame 10 when the opening frame is closed, as illustrated. By making the fixed frame 10, and its insulating strip 27 identical or nearly identical in construction with the moving frame 11,20, it is possible to economise considerably in the cost of dies and stocks.

The preferred material used in the thermal insulating strip 20, foamed microcellular polyvinylchloride, has a thermal insulat ing factor approximately three times better than that of any other rigid solid plastics material. An adequate and preferred thickness for this insulating strip is about 8 mm and preferably in the range between 6 and 12 mm. Since the fixed frame 10,27 can acquire strength from the surrounding subframe 28 or structure of the wall or other parts of the building, it may be preferred that the fixed frame 10 should itself be entirely formed of the rigid foamed insulating material without any metallic frame member.

The method of attaching the thermal insulating strip to the metallic frame may consist of or include other fixing systems; for example, the metal frame may be crimped or distorted so as to grip the insulating strip, or one or other part may be formed to engage the other as a press fit, for example with one part having a fir tree cross-section engaging a corresponding undercut cross-section in the other part.

Alternatively, or in addition, extra resilient locating clips may be provided to hold the two parts together. It is, however, preferred and important that the parts should be connected other than by rivets or screws which require laborious manual operations.

Thus as illustrated in the construction illustrated in Figure 2, like parts are indicated by the same reference numerals and will not be described again in detail. In this case the metal fixed frame 10 and insulating strip 27 are replaced by a foamed plastics frame 30 which combines the features of both, and provides that only insulating materials are exposed on the outer sides of the two frames when the window is closed.

A small hollow metal bead 31 may be secured to the frame 30 to close off the inner side of the gap between the two frames.

Figure 3 is a cross-section through the horizontal transom of a window frame having a lower fixed double glazing panel 40 and an upper opening double glazed vent panel 41. The transom itself is formed in two parts 42,43 both of extruded aluminium sections joined to form a hollow box with a front wall 44. This wall has a pair of projecting ribs 45 and secured to the front face of this wall is an elongated strip 46 of a plastics insulating material such as selfskinned foamed polyvinylchloride. This is attached in this case by means of an adhesive. Part 47 of this strip overlies the edge of the double glazing panel 41 and the gap may be closed with an elastomeric or mastic seal 48. The glazing panel is held in position by means of a glazing bead 49 secured to the transom, with another intervening resilient sealing element 50.

The frame of the opening vent includes a lower frame member 51 formed as an extruded aluminium section and this has a pair of ribs 52 on its front flange 53, to locate one edge of a combined anchoring and glazing bead extrusion 54 whose other edge 55 is located in a formation 56 provided on the rear or inner edge of the frame member 51. With an intervening resilient sealing strip 57 against the rear face of the double glazing panel 41 and a layer of mastic 58 against its front face, the glazing panel is located between the glazing bead 54 and the front flange 53 of the frame member.

Rigidly secured to the front face of the frame member is a thermal insulating strip 60 which is identical in profile to the strip 46 and is secured in position engaging the ribs 61 on the front face of the flange 53, by means of an adhesive. This strip 60 overlaps the mastic 58 and the edge of the glazing panel 41 and when the vent is closed the strip also overlaps the fixed transom cover strip 46. Along its lower inner edge the insulating strip 60 has an undercut groove 62 receiving a flexible sealing strip 63, which engages the front face of the cover strip 46 and makes a weatherproof seal.

Essentially the same construction is applied around all four edges of the moving vent and the cover strip 46 extends around all four sides of the lower fixed panel. Thus when the vent is closed all the front surfaces of the fixed and moving frame members are covered with insulating material which also covers the edges of the glazing panels thus greatly reducing heat transfer through the frames, and attendant problems.

The construction illustrated in Figure 4 is in many respects similar to that of Figure 1, and like parts are indicated by the same reference numerals with a suffix added. In this case the insulating strips 27', 20' are applied to the internal faces of the fixed and opening frame members 10', 11', and close against each other when the window is closed, via the sealing element 26'. This is an efficient method of preventing or reducing condensation, and reduces the risk of damage or deterioration of the insulation if exposed externally.

WHAT I CLAIM IS: 1. A frame for a window, door, or vent, including a metal frame member having a separately formed insulating strip of a foamed self-skinned plastics material attached to the metal frame member on a surface thereof which would otherwise be exposed when the window, door or vent is closed, substantially to cover said surface.

2. A frame according to claim 1, in which the insulating strip is formed with one or more grooves, keyways, ribs or slots to engage, interkey or interlock with corresponding formations on the metal frame member.

3. A frame according to claim 1 or claim 2, in which the insulating strip is bonded to the frame member or attached by an adhesive.

4. A frame according to any of the preceding claims, in which the insulating strip is provided with means to support a sealing strip to engage another, relatively movable, frame.

5. A frame according to any of the preceding claims, fitted with a glazing panel or a double ;lazing panel and in which the insulating strip engages the outer edge or face of the panel.

6. A frame according to any of the preceding claims in which the insulating material covers only the exposed external surfaces of the frame.

7. An opening window, door, or vent, framed construction having fixed and movable frames, both in accordance with any one of the preceding claims.

8. An opening frame construction according to claim 7, wherein the insulating cover strip on the opening frame overlaps the insulating cover strips on the fixed frame, when the opening frame is closed.

9. A window frame substantially in any of the forms herein described with reference to and as shown in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. located between the glazing bead 54 and the front flange 53 of the frame member. Rigidly secured to the front face of the frame member is a thermal insulating strip 60 which is identical in profile to the strip 46 and is secured in position engaging the ribs 61 on the front face of the flange 53, by means of an adhesive. This strip 60 overlaps the mastic 58 and the edge of the glazing panel 41 and when the vent is closed the strip also overlaps the fixed transom cover strip 46. Along its lower inner edge the insulating strip 60 has an undercut groove 62 receiving a flexible sealing strip 63, which engages the front face of the cover strip 46 and makes a weatherproof seal. Essentially the same construction is applied around all four edges of the moving vent and the cover strip 46 extends around all four sides of the lower fixed panel. Thus when the vent is closed all the front surfaces of the fixed and moving frame members are covered with insulating material which also covers the edges of the glazing panels thus greatly reducing heat transfer through the frames, and attendant problems. The construction illustrated in Figure 4 is in many respects similar to that of Figure 1, and like parts are indicated by the same reference numerals with a suffix added. In this case the insulating strips 27', 20' are applied to the internal faces of the fixed and opening frame members 10', 11', and close against each other when the window is closed, via the sealing element 26'. This is an efficient method of preventing or reducing condensation, and reduces the risk of damage or deterioration of the insulation if exposed externally. WHAT I CLAIM IS:

1. A frame for a window, door, or vent, including a metal frame member having a separately formed insulating strip of a foamed self-skinned plastics material attached to the metal frame member on a surface thereof which would otherwise be exposed when the window, door or vent is closed, substantially to cover said surface.