GB2128236A

GB2128236A - Thermally-insulating frame members

Info

Publication number: GB2128236A
Application number: GB08326248A
Authority: GB
Inventors: Derek Ronald Lancaster
Original assignee: RTZ Extruders Ltd
Current assignee: RTZ Extruders Ltd
Priority date: 1982-10-05
Filing date: 1983-09-30
Publication date: 1984-04-26
Also published as: GB8326248D0; GB2128236B

Abstract

Composite frame members for doors or windows are made by assembling plastics and metal sections, having interfitting features, so as to leave a channel shaped recess or cavity between the plastics and metal sections, and filling this channel-shaped recess with an insulating resin and allowing it to cure, thus locking the sections together. <IMAGE>

Description

SPECIFICATION Improvements in or relating to composite door or window sections This invention relates to door or window frame sections in which there is a requirement to provide thermal insulation between internal and external surfaces of the frame.

The greatly increased use of metal door and window frames, both in the replacement window and double glazing fields has led to a requirement that there should be a thermal barrier between internal and external surfaces of such frames in order to reduce or to prevent condensation on the inner frame surfaces due to heat being conducted from inner to outer surfaces of the frame.

Various methods have been proposed in the patent literature, to provide a "thermal-break" between the inner and outer surfaces of window and door frames. One of the earlier was in U.S.

patent 3,204,324 dated 7th September 1965 in which a channel in a metal extrusion is filled with insulating resin in the liquid state and, after the resin has set and been cured, the channel bottom is cut away, leaving an insulating resin bridge between the remaining metal sections. A similar solution is described in British patent specification 1,040,204 dated 24th August 1966.

Since late 1 960's many attempts have been made to provide thermal breaks in metal window frames. These have fallen into two main categories, those in which the thermally-insulating section is formed by a "fill and break" technique on a metal section with a channel-shaped feature in its profile and those based on a "clip-together" system wherein projections on plastics sections are made to fit into recesses in metal sections so as to form a metal/plastics/metal sandwich. The main drawbacks of the "fili and break" systems are the requirement for accurate resin mixing, proper curing time, leakage of resin into cavities and the weakening of the resin section which can occur when the metal bridge is sawn or milled away.The main disadvantages of the "clip together" system are the difficulty of locating the sections accurately together, and the problems of inadequate rigidity which result from inaccurately fitting metal and plastics sections. Thus any degree of looseness in the composite section leads to problems in subsequent manufacturing operations.

The invention proposes to overcome the disadvantages of both previously proposed systems According to this invention we provide a method of manufacturing composite door or window frame sections having at least one thermally-insulating section attached to a metal section, comprising assembling together sections formed from a plastics extrusion and a metal extrusion, having cooperating features, so as to leave at least one open channel-shaped recess between plastics and metal sections, and then pouring a non-expanding insulating resin into said open channel-shaped recess and allowing it to cure therein to lock the plastics and metal sections together.

Preferably the cooperating features include a first datum face on the metal extrusion and a second datum face on the plastics extrusion which are urged together to locate the metal and plastics extrusions in spaced, substantially parallel alignment. The provision of these datum faces facilitates the assembly of the extrusions to within required tolerances as to spacing and parallelism.

The cooperating features may further include a deformable clip provided on one extrusion, preferably on the plastics extrusion, for cooperation with a complementary formation provided in the other extrusion.

Advantageously, the clip comprises two resilient spaced apart legs which are resiliently movable together and apart for engagement with the complementary formation provided on the other extrusion. A formation may be provided on each extrusion, each formation being arranged to be embedded in the cured resin in the open channel shaped recess.

By "open channel-shaped recess" we mean a recess which is closed on 3 sides but open on one side into which the resin is added.

Since the resin is to be allowed to cure in the open channel shaped recess, it will be understood that the resin must be substantially nonexpanding.

Preferably the resin is a pre-mixed mixture of polyol/polyisocyanate which sets and cures to form a rigid polyurethane insulating bridge.

The advantages of the manufacturing method according to the invention are as follows: 1. No machining-away of metal bridges is required.

2. A good insulating performance is achieved.

3. Tolerances between plastics and metal section is not as critical as in previous systems, since strength and sectional integrity is achieved by resin introduction.

4. Resin helps prevent ingress of moisture between sections.

5. The method is especially advantageous where large cross-section rails e.g. for doors, are to be constructed.

The invention will now be further described by reference to the accompanying sheet of drawings in which; Figure 1 shows a section through a window frame member with interfitting metal and plastics sections before resin is poured to bond them together.

Figure 2 shows the same section after resin has been poured and cured.

Figure 3 shows a section of large area with double interfitting formations and two channels filled with resin.

With reference first to Figure 1 , the metal extruded section 1 and the plastics extruded section 2 are assembled together by means of legs (2A, 2B) on the plastics section fitting into the recess ( 1 A) within the metal section 1. Stop means (2C) on plastics section 2 prevents the legs (2A, 2B) from penetrating too deeply into the recess by abutting against one of the recess sides as shown. Thus datum faces 4 are fitted together.

A recess 5 is left between the plastics and metal on assembly.

In Figure 2, the same section is shown after pouring and curing resin into the channel-shaped recess 5 of Figure 1. This leads to the formation of thermally-insulating insert 3 between the plastics and metal sections 1 and 2 which serves to hold them rigidly apart.

In Figure 3, there are double recesses 1 A and 1 B formed in the metal section and two pairs of legs (2A, 2B and 2C, 2D) formed on the plastics extrusion. These interfit into recesses 1A and 1 B while resin is being poured into channel-shaped recesses to form rigid insulating resin inserts 3 as shown in Figure 3.

In the embodiments shown in Figures 2 and 3 the sections 1, 2 are each provided with a projecting formation 6 arranged to be embedded in the cured resin insert 3.

Claims

1. A method of manufacturing composite dooror window-frame sections having at least one thermally-insulating section attached to a metal section, comprising assembling together sections formed from a plastics extrusion and a metal extrusion, having cooperating features, so as to leave at least one open channel-shaped recess between plastics and metal sections, and then pouring a substantially non-expanding insulating resin into said open channel-shaped recess and allowing it to cure therein to lock the plastics and metal sections together.

2. A method as claimed in Claim 1 wherein the cooperating features include a first datum face on the metal extrusion and a second datum face on the plastics extrusion which are urged together to locate the metal and plastics extrusion in spaced substantially parallel alignment.

3. A method as claimed in Claim 1 or 2 wherein one extrusion is provided with a deformable clip for cooperation with a complementary formation provided on the other member.

4. A method as claimed in Claim 3 wherein the deformable clip comprises two resilient spaced apart legs which are resiliently movable together and apart for engagement with the complementary formation.

5. A method as claimed in any preceding Claim in which each extrusion is provided with a formation arranged to be embedded in the cured resin in the open channel shaped recess.

6. A method of manufacturing a composite door or window section substantially as described with reference to the accompanying drawings.