GB2320048A

GB2320048A - Hollow extruded plastics frame filled with settable foam

Info

Publication number: GB2320048A
Application number: GB9625279A
Authority: GB
Inventors: Trevor Vella Tomlin
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-12-04
Filing date: 1996-12-04
Publication date: 1998-06-10
Also published as: GB9625279D0

Abstract

A frame comprising lengths of hollow plastics extrusion 2 joined at their ends defining an internal chamber filled with a settable foam material 4. The foam material 4 may be of plastics material and is injected at an injection hole 3 drilled in the frame while another hole 3 is provided to let air escape from the frame as it is filled. Other particles may be added to the foam 4 to improve its strength and/or rigidifying effect. Some extrusions 2 may include internal strengthening webs 5 partitioning the hollow interior into separate chambers which may be selectively filled by drilling suitable holes 3 as described.

Description

Manufacture of Window Frames and the like.

This invention relates to frames, namely window frames, door frames and the like which are assembled from cut lengths of extruded plastics material, e.g.

PVC.

It is well known to manufacture window frames using hollow plastics extrusions, the cut lengths of extrusions being fixed together, such as by welding, at the corner joints of the frame. With a view to improving economy, it has become the practice to make the material of the plastics extrusions as thin as possible, but the reduction in thickness of the material has the undesirable effect of reducing strength, and the rigidity of the extrusions and the assembled frame suffers.

The present invention resides in an elegantly simple and economic solution to the above problem and in accordance with one aspect the invention resides in a method of manufacturing a frame comprising connecting lengths of hollow extrusion, and injecting a settable foam material substantially to fill the interstices of a chamber within the hollow extrusions.

According to another aspect the invention provides a window, door or similar frame comprising plastics extrusions joined at their ends and defining an internal chamber filled with a rigidifiing foam material.

By the invention a frame of substantially greater rigidity is obtained than if the unfilled hollow extrusions were used alone. Furthermore, the heat insulating performance, or the so-called "U" value of the frame, is significantly enhanced.

The cost of filling the extrusions with foam is relatively low and does not add substantially to the frame manufacturing costs so that the advantages of economy gained in using thin walled extrusions are largely retained.

The filling foam material is preferably a plastics material which sets hard to form a substantially rigid body. Such foam materials are readily available on the market and are commonly used in the building industry to fill and seal gaps, e.g. between window and door frames and surrounding wall structures. Such foam materials can be purchased in canisters and typically expand around 7 to 10 times upon being dispensed and before solidifying. The foam material can be injected at a single point of a frame several metres in perimetral length and the foam will naturally flow to fill entirely the interstices of the hollow extrusions forming the frame, the foam subsequently setting to define a reinforcing core within the frame.

If desired, particles such as aluminium filings, fibres or the like can be incorporated in the settable foam, as known per se, to improve further the strength and rigidifying effect of the foam core.

If the extrusions include intemal strengthening webs partitioning the hollow interior into separate chambers it is not essential for all the chambers to be filled with foam. However, as the internal webs are generally very thin a foam injection hole can be drilled to span a web and allow adjacent chambers to be filled simultaneously.

The invention is further described below, with reference to the accompanying drawings in which: Figure 1 is a schematic illustration of a window frame assembled from extruded plastics; Figure 2 is a schematic cross-section through the foam filled frame; and Figures 3a to 3f show typical window and door frame sections with internal chambers filled with a reinforcing foam according to the invention.

The frame I is assembled from cut lengths 2 of hollow PVC extrusion which are mitred and flised together at the frame corners. A hole 3 is drilled, e.g.

adjacent one corner of the frame and through this hole is injected the settable plastics foam material. A further hole 3 is drilled at an opposite location to allow the air within the frame to escape as it becomes filled with the foam. The expanding foam travels completely around the hollow interior of the frame so that the interstices of the extrusions become filled with the foam 4 which sets hard.

Of course, if preferred or felt desirable foam could be injected through two or more holes at spaced intervals around the frame. A frame of much improved strength and heat insulation characteristics is obtained at relatively low additional cost.

Whereas Figure 2 shows a very schematic cross-section, Figures 3a to 3f illustrate typical frame sections to be found in doors and windows. In each case the plastics extrusion 2 includes internal webs 5 which help to prevent buckling of the outer walls of the extrusion during frame assembly and which are generally very thin, e.g. typically around 0.5mm. The webs 5 form partitions separating chambers, any of which can be filled with foam by the method described above by injecting foam through holes drilled to connect to the chambers to be filled. As the webs 5 are thin the injection holes 3 can be formed at the location of a web 5 and to span the web so that two adjacent chambers will be filled simultaneously by injection of foam through a single hole. Of course corresponding air holes will be provided to allow escape of air from the chambers during their filling with foam. The chambers filled with foam 4 are shown cross-hatched in Figures 3a to 3f, and in each case at lest a major part of the internal cross-section of the extrusion is shown foam filled. The particular frame sections of Figures 3a to 3f are as follows: Figure 3a is an outer frame member of a window; Figure 3b is a window transom frame member; Figure 3c is a window vent frame member; Figure 3d is a frame member for a glazed door; Figure 3e is a door sash or midrail frame member; and Figure 3f is a door vent frame member.

In some of the Figures appropriate injection hole positions which can be used are shown denoted by the numeral 3. If desired, e.g. for aesthetic reasons, the injection and air holes can be plugged or capped after foam injection is complete.

Claims

Claims:

1. A method of manufacturing a frame comprising connecting lengths of hollow extrusion, and injecting a settable foam material substantially to fill the interstices of a chamber within the hollow extrusions.

2. A method of manufacturing a frame, such as a door or window frame, comprising the steps of connecting cut lengths of hollow plastics extrusions so that the hollow interiors of the extrusions define a substantially closed chamber, and injecting settable foam material substantially to fill the interstices of the chamber.

3. A method according to claim 1 or 2, wherein the foam material is a plastics material which sets into a substantially rigid body within the chamber.

4. A method according to claim 3, wherein the plastics foam includes filling particles or fibres to improve the strength of the foam when set.

5. A method according to any one of claims 1 to 4, wherein the foam material is injected into the chamber at a first location and during the injection air is allowed to escape from the chamber at a location remote from the first location.

6. A method according to claim 5, wherein the first and second locations are at diametrically opposed corners of the frame.

7. A method according to any one of claims 1 to 6, wherein the extrusions have internal partitions separating chambers within the frame, an injection opening is positioned to span a partition, and foam material is simultaneously injected into the adjoining chambers separated by said partition.

8. A method according to any one of claims 1 to 7, wherein holes provided in the extrusions for the purpose of injecting the foam are plugged or capped after foam injection is complete.

9. A window, door or similar frame comprising plastics extrusions joined at their ends and defining an internal chamber filled with a rigidifying foam material.

10. A frame according to claim 9, wherein the extrusions are welded together at the joins between the extrusions.

11. A frame according to claim 9 or 10, wherein the frame has greater heat insulation performance than a corresponding frame without the foam filling.

12. A frame according to claim 9,10 or 11, wherein the extrusions have internal portioning webs separating chambers therein, at least one but not all the chambers being filled with rigidifying foam material.

13. A frame according to claim 12, wherein a major part of the internal volume of the extrusions is filled with rigidifying foam.

14. A method of manufacturing a frame substantially as herein described.

15. A frame substantially as herein described with reference to the accompanying drawings.