GB2430720A

GB2430720A - Frame construction

Info

Publication number: GB2430720A
Application number: GB0516352A
Authority: GB
Inventors: Ramon Rabett
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-08-09
Filing date: 2005-08-09
Publication date: 2007-04-04
Anticipated expiration: 2025-08-09
Also published as: GB0516352D0; GB2430720B

Abstract

A joint connecting two sections (30, 31) of a plastics material profile includes opposed external faces (32, 33) and an interconnecting matrix (35, 36, 37). The interconnecting matrix (35, 36, 37) at the end of each section (30, 31) is cut at complementary angles to form a mitred joint. The external faces (32, 33) are cut to form butt joints. The joint may be used in the construction of window frames, such as PVC-U window frames.

Description

-1- 2430720 Frame Construction The present invention relates to a join

formed between profile sections.

It further relates to methods of forming such joins and to frames constructed using such joins.

In the window manufacturing industry, new windows are frequently but not exclusively constructed from plastics material such as PVC-U, as this is has many advantages. However, a major disadvantage of such plastic windows is that their visual appearance differs to that of original wooden windows which they are often attempting to emulate. This is due to differences in construction techniques between wooden and plastic windows and the inherent characteristics of the material. A particular issue in plastic windows having fames formed from four sections joined at the corners is that welded mitred joins need to be used. In contrast wooden windows are butt joined, which gives a quite different visual appearance. The complex profiles, which are usually formed by extrusion or like techniques, that are used to form the frames for plastic windows are not suitable for butt joining, due to the incompatibility of complex shapes and the poor join strength achieved.

The present invention aims to overcome this problem and to provide a way in which lengths of a complex profiled plastic extrusion can be easily joined to give the appearance of a butt join, but the strength and manufacturing convenience of a mitred join.

Therefore according to the present invention there is provided a join between two sections of a plastics material profile, the profile having opposed external faces and an interconnecting matrix, the interconnecting matrix at the end of each section being cut at complimentary angles to form a mitred joint, and the external faces being cut to form butt joints.

The sections of plastics material profile usually comprise lengths of a complex profiled plastic extrusion from which window frames are constructed.

The profiled does not, however, have to have been formed by extrusion, a profile formed by any other suitable method may still be used. The matrix extending between the external faces can be substantially solid, or can comprise an arrangement of interconnecting walls that may define spaces therebetween.

The term plastics material, as used herein to describe the sections of profile, encompasses materials partially or exclusively consisting of plastics material. The term includes composite materials such as fibreglass, composite materials consisting of PVC-U with fillers such as sawdust, as well as normal plastic material such as PVC-U.

The present invention is equally applicable to a main frame for mounting of a window of any type (or indeed other structure such as a door) or a sub-frame (such as sash panel in a sliding sash window, a casement vent or a door leaf) which is mounted within an outer frame.

Window frames, which term includes door frames and the like, are usually constructed as regular four sided rectangular shapes. Therefore, there are usually four right angle connections, which prior to the present invention had to be formed by four 45 mitred joins. In the present invention it is therefore usual that the butt joints are made at a right angle and the mitred joint is formed at substantially 450* This is achieved by cutting the matrix at the end of each section at an angle of 45 to the length of the each section, which are generally elongate.

The external faces, which in a window would face into and out of a building, are preferably substantially parallel to each other. They are also preferably defined by the outside surface of external walls interconnected by the matrix. The profile of the sections also generally defines inner and outer sides extending between the opposed external surfaces. These inner and outer sides are rarely flat or linear, but they face generally into or out of a frame formed in the plane thereof. Again, in a window the inner side would be directed toward an item mounted in the frame, and the outer side would be directed toward the structure in which the frame is mounted. The external faces, in contrast, would preferably face generally perpendicular to the plane of the window - such as into or out of a building.

The ends of the external walls can be formed, by cutting, at a right angle to the length of each section. On one section of each join the external face may be cut at a right angle at the point where the plane of the angled mitre region intersects the inner face adjacent that external face. For a profile that has external faces of equivalent width this point will be the same on both external faces, however in the case where they are different widths (such as on the profile of a double hung sash window that is stepped) the external faces on each side will be cut to terminate at different points. On the other section of a join, each external face is cut at a right angle at the point where the plane of the angled mitre region intersects the outer side adjacent that external face. Again this can be at equivalent or different points dependent on the configuration of the profile.

According to the present invention there is also provided a method of forming a join between two elongate sections of extruded profile having opposed inner and outer walls and an interconnecting matrix, comprising cuffing the end of each section of profile such that the inner and outer walls are cut square; cuffing the matrix on each section at an angle to form a mitred joint to the other section; and welding the ends of the sections together so that the angled cut regions of matrix form a mitred joint and the square cut inner and outer faces form butt joints.

The method is subject to many of the same preferred aspects as are discussed above with respect to the join. For example it is preferred that the matrix of each section is cut at substantially 450, and the sections are joined at 9Q0 to each other. It is also preferred that the sections are joined by heat welding, but other methods such as epoxy glues are possible. Cuffing of the ends of each section of profile is achieved by any appropriate method, but precision milling using appropriately shaped cutting heads is convenient.

According to a third aspect of the present invention there is provided a frame formed from four sections of profile joined into a rectangle at four corners by a method according to the present invention, or including one or more join according to the present invention.

Such a frame may be used in the construction of plastic windows or doors of any type, including sash or casement windows. Further, several frames of different sizes may be combined for a composite window assembly.

In order that it may be better understood, but by way of example only the present invention will now be described in more detail with reference to the accompanying drawings in which: Figure 1 (prior art) is a view of a double-hung sliding sash window whose frames are joined by conventional mitred joints; Figure 2 is a similar view of a double-hung sliding sash window assembly in which the frames are joined according to the present invention with the appearance of butt joints; Figure 3A shows the end of a first length of profile cut to form a join according to the present invention; Figure 3B shows the end of a separate second length of profile cut in a complementary way so as to fit to the length of profile shown in Figure 3A; and Figure 4 is a view of the two sections of profile in Figures 3A and 3B joined at a right angle.

Figure 1 shows a conventional double-hung sliding sash window assembly generally indicated 10. The assembly comprises an outer frame 11 within which are slidably mounted a lower inner frame 12 and an upper inner frame 13. Each of the frames is formed from four sections of plastic extrusion having an appropriate cross-sectional profile. Each frame is formed from four elongate lengths of sections joined at the corners with 450 mitres. Weld lines 14 are visible at the corner of each frame showing the position of the mitres.

Unfortunately, these angled weld lines 14 create a visual appearance which is at odds with the desired emulation of wooden windows, whose butt joints do not create such diagonal marks.

Figure 2 shows a window assembly formed using the teachings of the present invention. This window assembly, generally indicated 20, again comprises an outer frame and upper and lower inner frames which are again numbered 11 to 13. However, in window assembly 20 each frame is formed so that the external appearance is that of a butt join. This is provided by the weld lines 21 which are either parallel to or perpendicular to the length of the sections of profile.

Figures 3A and 3B show the ends of two lengths of plastic extrusion which are cut in order that they may be joined according to the present invention. The extrusion in each instance is of identical cross-section but has been cut differently so as to be complementary. A first section 30 is shown in Figure 3A and a second section, generally indicated 31, is shown in Figure 3B. In each case the sections have a first external waIl 32 and a second external wall 33. Extending between these external walls 32 and 33 is a web of several interconnecting walls including a base waIl 35, inner wall sections 36 and vertical walls 37. Together the constituent walls 35, 36 and 37 comprise a matrix, whose overall shape is dependent upon the design of the profile and is not material to the present invention. For simplicity in the currently illustrated embodiments the matrix is of a relatively simple design, but the invention is equally applicable to far more complicated profiles or ones that are substantially solid.

In Figure 3A the constituent walls 35 36 37 of the matrix of the first section 30 are cut at an angle of 450 (to the length of the section). The first and second external walls are cut at a right angle, to the length of the first section 30, at a point level with the lower edge of the angle cut matrix. This means that the external walls 32 and 33 extend beyond the matrix for most of the width of the profile.

In Figure 3B a complementary end formation of a profile is shown. An equivalent 450 mitred cut is formed on the matrix of the base waIl 35, inner wall sections 36 and vertical walls 37 etc. However, the internal and external walls 32 and 33 are cut at a right angle at a point level with the inner (uppermost as viewed in this drawing) edge of the angle cut matrix.

Effectively the inner and outer walls are cut to correspond either with the point where the plane of the mitre intersects the inner or the outer sides of the sections.

Figure 4 shows a right angled join between the first section 30 and the second section 31. As the sections are brought together the angle cut faces of the base wall 35, vertical walls 37 and inner wall sections 36 come together and may all be fixed together by appropriate techniques such as heat welding, ultra-sonic welding or adhesives. The dotted lines on Figure 4 indicate approximate areas of overlap or abutment and consequently are areas for potential interconnection. End edges 40 of the first and second external walls 32 and 33 of the first section 30 extend to the outermost edge 41 of the second section. Terminal edges 43 of the first and second external walls 32 and 33 of the second section 31 abut lateral edges 44 on the first section 30.

The abutment, welded or otherwise, of the terminal edges 43 and lateral edges 44 provides the external appearance of a butt join on the visible faces of the frame. However, the concealed internal mitred joint provides the convenient and strong method of connecting the sections 30 and 31 together.

Mitred joints are particularly convenient because they allow the neat connection at right angles of complicated non-symmetrical profiles which could not be connected by conventional butt joining techniques, even if additional external structural elements were provided to aid that interconnection.

The present invention therefore provides a mechanism by which complex plastic extrusions may be joined by conventional welding techniques to form a strong yet visually appealing arrangement without the use of any external connecting brackets or the like.

Claims

Claims 1. A join connecting two sections of a plastics material profile,

the profile having opposed external faces and an interconnecting matrix, the interconnecting matrix at the end of each section being cut at complimentary angles to form a mitred joint, and the external faces being cut to form butt joints.
2. A join as claimed in claim 1, wherein the butt joints are made at a right angle and the mitred joint is formed at 45 .
3. A join as claimed in claim I or claim 2, wherein the external faces are substantially parallel to each other.
4. A join as claimed in any of the preceding claims wherein the profile includes external walls that are connected to the matrix and which define the external faces.
5. A join as claimed in any of the preceding claims, wherein profile is an extruded window frame profile.
6. A join as claimed in claim I and substantially as herein described with reference to and as illustrated in the accompanying drawings.
7. A method of forming a join between two elongate sections of profile having opposed inner and outer walls and an interconnecting matrix, comprising cutting the end of each section of profile such that the inner and outer walls are cut square; cutting the matrix at the end of each section at an angle to form a mitred joint to the other section; and welding the ends of the sections together so that the angled cut regions of matrix form a mitred joint and the square cut inner and outer faces form butt joints.
8. A method of forming a join as claimed in claim 7, wherein the matrix of each section is cut at substantially 450, and the sections are joined to each other at 900.
9. A method as claimed in claim 7 or claim 8, in which the sections are joined by welding or gluing.
10. A method as claimed in any of claim 7 to claim 9, in which the sections are cut by electronic milling machine.
11. A window frame formed from four sections of profile joined into a rectangle at four corners by a method according to any one of claims 7 to claim 10.
12. A window frame including one or more join as claimed in any of claims I to 6.