GB2077333A

GB2077333A - Improvements in or relating to cladding for metal frame members

Info

Publication number: GB2077333A
Application number: GB8015948A
Authority: GB
Original assignee: Consort Aluminium Ltd
Current assignee: Consort Aluminium Ltd
Priority date: 1980-05-14
Filing date: 1980-05-14
Publication date: 1981-12-16

Abstract

In a plastics clad metal frame, the portion of the frame member 10 which is to be clad is formed with a longitudinal pivot edge 14 and a longitudinal channel 16 spaced from and parallel to the pivot edge. The cladding strip 12 is formed with a longitudinal groove 15 to receive the pivot edge 14 and a resilient hook- shaped longitudinal formation 17 projecting rearwardly of the cladding strip and shaped and located so as to be received in the channel 16 when the pivot edge 14 is received in the groove 15. The hook-shaped formation 17 resiliently engages both side walls of the channel 16 thereby to retain the cladding strip in position on the metal frame member. Part of the formation 17 and one wall of the channel 16 have interengaging teeth to improve the retention. <IMAGE>

Description

SPECIFICATION Improvements in or relating to cladding for metal frame members The invention relates to cladding for metal frame members and particularly, but not exclusively, to plastics thermal cladding for extruded aluminium window frames.

As is well known, it is desirable to apply cladding to the internal and/or external surfaces of aluminium window frame members, not only to improve the appearance of the frame but also to reduce condensation and heat transfer through the frame. It has been proposed that such cladding, which is usually of plastics material, be secured to the aluminium frame members by adhesive, but cladding by this method is a comparatively skilled operation. Consequently, there is a requirement for a form of cladding where the cladding and frame members have interengaging formations for retaining the cladding on the members, so that the cladding may be easily fitted. In one known construction, the plastics cladding is formed with a longitudinal channel which engages over a projecting wall on the frame member, the sides of the wall being formed with teeth or ridges to engage the sides of the channel.It is found in practice, however, that such cladding must be manufactured to fairly fine tolerances since if the dimensions and location of the channel are not absolutely accurate, the engagement of the wall on the frame member within the channel can cause severe stresses in the material of the cladding, such stresses frequently leading to fracture of the cladding. The present invention sets out to provide an improved cladding arrangement which permits greater tolerances in manufacture.

In the present specification the "rearward" side of the cladding is that side which faces the metal frame member.

According to the invention there is provided, in combination, an elongate metal frame member and a cladding strip for application to a portion of the frame member, the portion of the frame member which is to be clad being formed with a longitudinal pivot edge and a longitudinal channel spaced from and parallel to said pivot edge, the cladding strip being formed with a longitudinal groove to receive said pivot edge and a resilient longitudinal formation projecting rearwardly of the cladding strip and shaped and located so as to be received in said channel when said pivot edge is received in said groove, the formation resiliently engaging both side walls of the channel thereby to retain the cladding strip in position on the metal frame member.

In use, the groove in the cladding strip is first applied to the pivot edge and the strip is then swung about the pivot so formed, bringing the resilient formation on the cladding strip into engagement within the channel on the frame member.

Preferably the pivot edge is closely received in said groove. For example, the pivot edge may be formed with an enlarged bead having a partcircular cross-section, the groove having a corresponding part-circular cross-section.

The resilient formation on the cladding strip may comprise, in cross-section, a narrow projection which resiliently engages one side wall of the channel and then extends across the channel to engage the other side wall. For example, the projection may be generally C-shaped or hook-shaped.

The side walls of the channel, and/or the parts of the resilient formation which engage them, may be formed with teeth or ridges to improve the retention of the resilient formation within the channel.

Alternatively or additionally, one side wall of the channel may be formed with a projection past which an end or shoulder on the resilient formation is snapped as the resilient formation is introduced into the channel, so as to assist in retention of the resilient formation within the channel.

The invention includes within its scope a window frame or cladding strip suitable for use in the combination referred to above.

An embodiment of the invention is shown in the accompanying drawings in which: Figure 1 is a cross-section through engaging thermally clad window frame and sash members, and Figures 2 to 5 are cross-sections through thermally clad window transoms.

Referring to Figure 1, the window frame member 10 and sash member 1 1 are extruded from aluminium and have attached thereto thermal cladding strips 12 and 13 of resilient plastics material. The cladding strips 12 and 13 are identical, as are the corresponding formations on the window frame and sash members, and only one assembly will therefore be described.

The window frame member 10 is formed with a pivot edge 14 in the form of an enlarged bead of part-circular cross-section which is received in a groove 15 of corresponding part-circular crosssection in the cladding strip 12. The frame member 10 is also formed with a channel 16, spaced from the enlarged bead 14, into which channel extends a generally C-shaped, or hookshaped, resilient formation 1 7 projecting rearwardly from the cladding strip. To apply the cladding strip to the frame member, the groove 15 in the cladding strip is first located over the enlarged bead 14 and the strip is then swung about the pivot so formed until the hook-shaped formation 17 is resiliently engaged within the channel 1 6. The unstressed shape of the hookshaped formation 17 is such that it resiliently engages both side walls 1 8, 19 of the channel.As illustrated, one side wall 1 9 of the channel 1 6 is formed with ridged teeth 20 which are engaged by corresponding ridges 21 formed on the hookshaped formation. The ridges on the hook-shaped formation may be omitted if required, the plastics material preferably being such that the teeth 20 bite into the material.

To assist in the retention of the hook-shaped formation 17 in the channel 16, a longitudinal bead (shown dotted at 22) may be formed in the side wall 18 of the channel opposite to that formed with the teeth 20, so that the free end 23 of the hook-shaped formation snaps over the bead 22 as it is inserted into the channel.

It will be appreciated that the particular shape illustrated for the resilient formation on the cladding strip is given by way of example only, and there will be many alternative forms of resilient formation which will resiliently engage both side walls of the channel 16 in suitable manner. The particular arrangement shown, however, has the advantage that the formation will resiliently engage both side walls of the channel with comparatively wide tolerances in the dimensions and location of the resilient formation on the cladding strip.

Figures 2 to 5 show modified versions of the cladding strip applied to transoms of window frames. In these arrangements the aluminium transoms are formed with opposed enlarged beads enaging grooves in the cladding, and consequently the resilient formations are omitted from the cladding strips which are slid longitudinally onto the transoms.

Claims

1. The combination of an elongate metal frame member and a cladding strip for application to a portion of the frame member, the portion of the frame member which is to be clad being formed with a longitudinal pivot edge and a longitudinal channel spaced from and parallel to said pivot edge, the cladding strip being formed with a longitudinal groove to receive said pivot edge and a resilient longitudinal formation projecting rearwardly of the cladding strip and shaped and located so as to be received in said channel when said pivot edge is received in said groove, the formation resiliently engaging both side walls of the channel thereby to retain the cladding strip in position on the metal frame member.

2. The combination according to claim 1, wherein the pivot edge is closely received in said groove.

3. The combination according to claim 2, wherein the pivot edge is formed with an enlarged bead having a part-circular cross-section, the groove having a corresponding part-circular crosssection.

4. The combination according to any of claims 1 to 3, wherein the resilient formation on the cladding strip comprises, in cross-section, a narrow projection which resiliently engages one side wall of the channel and then extends across the channel to engage the other side wall.

5. The com-bination according to claim 4, wherein the projection is generally hook-shaped.

6. The combination according to any of claims 1 to 5, wherein the side walls of the channel, and/or the parts of the resilient formation which engage them, are formed with teeth or ridges to improve the retention of the resilient formation within the channel.

7. The combination according to any of claims 1 to 6, wherein one side wall of the channel is formed with a projection past which an end or shoulder on the resilient formation is snapped as the resilient formation is introduced into the channel, so as to assist in retention of the resilient formation within the channel.

8. The combination of an elongate metal frame member and a cladding strip substantially as hereinbefore described with reference to the accompanying drawings.

9. An elongate metal frame member, for use in the combination according to any of the preceding claims, the portion of the frame member which is to be clad being formed with a longitudinal pivot edge and a longitudinal channel spaced from and parallel to said pivot edge.

10. A cladding strip, for use in the combination according to- any of claims 1 to 8, the cladding strip being formed with a longitudinal groove to receive said pivot edge and a resilient longitudinal formation projecting rearwardly of the cladding strip.

11. An elongate metal frame member according to claim 9 and substantially as hereinbefore described with reference to the accompanying drawings.

12. A cladding strip according to claim 10 and substantially as hereinbefore described with reference to the accompanying drawings.