GB2319280A

GB2319280A - PVC window frames

Info

Publication number: GB2319280A
Application number: GB9723656A
Authority: GB
Inventors: Kevin Richards; Robert Thomas Newall
Original assignee: CESTRUM Ltd
Current assignee: CESTRUM Ltd
Priority date: 1996-11-09
Filing date: 1997-11-10
Publication date: 1998-05-20
Anticipated expiration: 2017-11-10
Also published as: GB9723656D0; GB2319280B

Abstract

The lower end of each upper jamb is joined to one end of the transom 40 and the upper end of the corresponding lower jamb 44 is joined to the same end of the transom. A sash window effect can be produced with a continuous vertical sight line. Typically, the transom is wider than each of the upper jambs and is joined first to the narrower jambs following which a corner section is removed to form a second joint surface to which the wider jambs are joined.

Description

A WINDOW FRAME The present invention relates to a uPVC window frame and, in particular, a casement or open-cut window frame which presents the visual appearance of a sash window.

A uPVC window frame is generally formed from two horizontal supports and two vertical jambs which are mitred at their respective ends so that the four parts can be arranged in a square or rectangle. A transom is frequently fitted between the two jambs. Traditionally, the popular uPVC window was a tilt and turn window but, more recently, casement and open out windows have increased in popularity.

Attempts have also been made to imitate classical window designs such as the sash window. Unfortunately, uPVC imitation sash windows have a serious drawback. As uPVC is extruded with a predetermined profile of constant crosssection, the recess defined by the inner profile of the top part of the outer window frame and the transom is, of necessity, of the same width as that defined by lower part and the underside of the transom. To secure the imitation sash to a uPVC window requires the outer profile of the sash frame to fit into the inner profile of the upper part of the outer frame which causes the inner profile of the sash frame to be disposed inwardly of the lower part of the outer frame. This arrangement breaks the vertical sight line of the inner profile of the window. Wooden versions of the same type of imitation could be produced by widening the inner profile of the upper part of the jambs so that an imitation sash can be fitted with an inner profile which aligns with the inner profile of the lower part of the Jambs and provides a continuous vertical sight line which more closely mimics the appearance of a genuine sash window. Unfortunately, this solution is not possible with uPVC windows which are extruded and have jambs of constant cross-section which are profiled and internally engineered to provide drainage channels and support. Vertical cutting of the upper part of the jamb would compromise the integrity of the drainage channels and/or the jamb supports and weaken the structure of the frame. An attempt to solve the problem has been attempted which utilises clip-on inner profiles placed adjacent the lower part of each jamb to effectively narrow the inner sight line of the lower window frame and produce a continuous vertical sight line with the inner profile of the sash. Unfortunately, this reduces the amount of light entering through the window and the clip-on parts tends to produce an undesired fabricated appearance.

As a result the general consensus in the industry is that satisfactory imitation sash window frames could not be produced with a continuous vertical sight line.

In a previous application by the applicants (UK No.

9615990.0), a solution to the above problem is provided by splitting the uPVC jamb so that the upper parts and the lower parts can be formed from differing extruded parts of differing widths. The upper jambs are generally narrower to allow an opening frame to be fitted therein with an inner profile which aligns with the wider lower jambs and gives the appearance of an aesthetic and continuous vertical sight line.

Traditionally, the transom is fixed to a continuous vertical jamb by: a) having its ends "V" profiled, b) making a " V" cut at the appropriate place on the inner profile of the vertical jamb and c) placing the end of the transom into the "V" notch provided.

Corresponding cuts are made on the opposite side of the recess to secure the other end other transom. Such a fixing method is not suitable for the present invention where the vertical jamb is separated into two parts at the point where the transom is to be fitted. Accordingly, an alternative fixing arrangement has been proposed.

However, a problem with the above techniques is the inherent weakness of a three component joint at the end of each transom which includes a split jamb. Such weakness is not present in the traditional PVC windows which have a continuous jamb which is joined to the transom around the former's mid-point. This invention relates to a method of reinforcing the three way joint whilst maintaining simplicity in relation to the cutting and joining techniques used to prepare the joint. The invention also relates to a window frame prepared by such a method.

Thus, according to the present invention there is provided a method of manufacturing a PVC window frame comprising the steps of: a) providing a pair of upper jambs, a pair of lower jambs and a transom, the width of each jamb of one pair being narrower than those of the other pair; b) joining each of the narrower jambs to a respective end of the transom by respective first joints; c) forming two second joint surfaces by removing a corner section in the region of each first joint; d) joining each of the other pair of jambs to respective second joint surfaces to form second joints.

Preferably, in which at least one corner section crosses the first joint, between the narrower jamb and the transom, so that the second joint surface crosses that first joint.

Preferably, in which both second joint surfaces cross respective first joints.

Preferably, in which one or both first joints is a mitred joint.

Preferably, in which the angle of the mitred joint is varied from 450 by up to +/- 20 .

Preferably, in which the or both first joints is formed by welding.

Preferably, in which the or both second joints is formed by welding.

Preferably, in which the narrower jambs are the upper jambs.

Preferably, in which the corner sections are removed by cutting or chopping.

Preferably, in which one or both second joint surfaces are partially mitred.

Preferably, in which one or both wider jambs has a partially mitred inner face corresponding to a respective second joint surface so as to abut against the second joint surface.

Preferably, in which the angled part of the partially mitred face of the wider jamb and the second joint surface do not extend to the outermost face of the window frame.

Preferably, in which a cut substantially parallel to the transom is made in the transom and upper jamb frame which extends inwardly until it meets the mitred part of the partially mitred face.

Preferably, in which the cut is substantially horizontal and the jambs are substantially vertical.

Preferably, in which the upper jambs are the narrower jambs and create a recess into which an imitation sash window may be fitted of suitable thickness to present a continuous vertical sightline on the inner window frame.

Preferably, in which the imitation moving sash part of the window is located in the lower part, the lower jamb being narrower than the upper jamb and the transom being wider than the respective lower jambs.

The invention also extends to a window frame manufactured according to the method of the invention.

Advantageously, the wider transom provides a small vertical drop below the lower edge of the mitred upper jamb and thus reduces the area of the existing mitred joint which it is necessary to cut out in order to provide a suitably sized welding face for the lower jamb.

Typically, the lower jamb has a partially angled inner face at its end which abuts against a corresponding outer facing partially angled face cut into the transom. Preferably, the corresponding angled faces of the transom and lower jamb do not extend to the outer face of the window frame.

In such an embodiment, a substantially horizontal cut is, typically, made in the transom and upper jamb frame which extends inwardly until it meets the angled face and provides a second welding surface whilst minimising the cut into the existing joint with the upper jamb.

Advantageously, the arrangement of having the vertical jamb in two parts allows the upper part to be narrower than the lower part so that imitation sash windows can be manufactured with a continuous sight line for the inner profile. Thus, preferably, the upper jamb part is narrower than the lower jamb part so that the opposing upper jambs provide a wider recess than the corresponding lower jambs.

As an alternative to the aforementioned invention, where the imitation moving sash part of the window is located in the lower part, the lower jamb would be narrower than the upper jamb and the transom would be wider than the respective lower jambs.

Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 displays a small uPVC window frame in accordance with the present invention; Figure 2 displays a window frame in accordance with the present invention with the sash element removed; Figure 3 shows an exploded view of the upper/lower jamb and transom profiles; Figure 4 displays a window frame in accordance with the prior art arrangements; Figure 5 shows an exploded view of the jamb and transom connected of the prior art arrangements; Figure 6 displays the prior art sash window frame showing the discontinuance vertical sight line; Figure 7a displays upper jambs and a transom, prior to assembly, in accordance with the present invention; Figure 7b displays upper jambs and a transom, after assembly, in accordance with the present invention; Figure 7c displays lower jambs, prior to welding; Figure 7d shows welded upper jambs and transom prior to welding with the lower jambs; Figure 8a displays the transom/jamb connections after assembly; and Figure 8b, c and d display cross sectional views of the upper jamb, lower jamb and transom respectively.

Referring to figure 1 an imitation uPVC sash window frame has a sash element (4) and a window frame (6). The outer window frame is defined by upper and lower horizontal supports (8, 10), an opposed pair of upper jambs (12a, b) and an opposed pair of lower jambs (14a, b). The window cavity is separated into an upper and lower part by a transom (16) which extends perpendicularly between and is secured to the opposed vertical jambs (12a, b & 14a, b).

The lower recess part of the frame and the sash window element part are each further divided by two equally spaced, parallel, vertical window support elements (18a, b and 20a, b) which are aligned with the corresponding support element in the other part. The embodiment described differs from the prior art arrangement shown in figures 4, 5 and 6 in that the upper jamb (12a, b) is a separate component and narrower than the lower jamb (14a, b). The jambs (30b) shown in figure 4 are continuous uPVC frame elements which are typical of those used in the industry. The effect of using such elements is that the sash element (32), which is necessarily a close fit with the cavity (34) formed in the upper part of the window frame, forms a narrower recess with its inner profile (36) than that provided by the inner profile (38) of the lower part of the window frame causing a discontinuous vertical sight line from the top to the bottom of the window frame.

Referring to figure 7a, a transom (40) has mitred faces (48, 49) at its ends to be welded with corresponding mitred ends (46, 47) on the upper jambs (42, 43). The transom (40) is wider than the upper jambs (42, 43) so that aligning the inner edge of the mitred faces of the respective parts causes the transom to extend beyond the outer edges of the upper jambs (42, 43). In addition, the longer lower edge of the transom is disposed below the lowest extent of the mitred face of each jamb and this provides greater material in the transom capable of being cut out to provide for the welding of the bottom jambs (44, 45). In practice, this means that a greater proportion of the existing welded joint remains unaffected by the second cut and weld, thus enhancing the overall strength of the joint.

Referring to figure 7b-d, a horizontal cut is made in the existing weld just above the lower outer edge of the upper jamb (42) which extends past the welded faces (46, 48) into the transom until it lies just beyond an imaginary point which is aligned with the inner profile of the upper jamb (42). A second cut (50) is made into the bottom edge of the transom, in the direction of the weld, at an angle of approximately 45O to meet the horizontal cut (50) at its innermost point. A corresponding series of cuts is made at the other end of the transom which are a mirror image of the cuts described. Complimentary cuts are made in the lower jambs (44, 45) to provide a close fitting second weld. Advantageously, the cut made just above the lower edge of the upper jamb causes the excess lateral material to be removed from the transom so that the lower jamb may be aligned with the upper jamb to provide a continuous sight line for the outer profile while, at the same time, maintaining a mitred edge of suitable depth on the second weld.

As can be seen from figure 8a, the cuts made in the ends of the transom and upper and lower jambs are such as to maintain the integrity of the profiles (50, 52) in the upper and lower parts of the window frame and also to form a sealed and durable connection between the transom and the upper and lower jambs.

Such an arrangement has not hitherto been used to connect transoms to jambs in uPVC window frames and solves the problem of producing an imitation sash window with a continuous vertical inner sight line and yet maintain a relatively straightforward production technique giving a joint of sufficient strength to match the continuous jamb versions.

It will be appreciated that the ends of the transom and the upper and lower jambs can be joined by any suitable welding technique. Preferably, the transom is integrated in such a manner that all drainage channels, grooves for the input of gasketry and beading are aligned. However, it is possible, in some instances, to have slightly misaligned or exposed drainage channels and gasketry so long as the strength requirements of the window frame are met.

Claims

1. A method of manufacturing a PVC window frame comprising the steps of: a) providing a pair of upper jambs, a pair of lower jambs and a transom, the width of each jamb of one pair being narrower than those of the other pair; b) joining each of the narrower jambs to a respective end of the transom by respective first joints; c) forming two second joint surfaces by removing a corner section in the region of each first joint; d) joining each of the other pair of jambs to respective second joint surfaces to form second joints.

2. A method according to claim 1, in which at least one corner section crosses the first joint, between the narrower jamb and the transom, so that the second joint surface crosses that first joint.

3. A method according to claim 2, in which both second joint surfaces cross respective first joints.

4. A method of manufacturing a PVC window frame according to any preceding claim, in which one or both first joints is a mitred joint.

5. A method of manufacturing a PVC window frame according to claim 4, in which the angle of the mitred joint is varied from 450 by up to +/- 200.

6. A method according to any preceding claim, in which the or both first joints is formed by welding.

7. A method according to any preceding claim, in which the or both second joints is formed by welding.

8. A method of manufacturing a PVC window frame according to any preceding claim, in which the narrower jambs are the upper j ambs.

9. A method according to any preceding claim, in which the corner sections are removed by cutting or chopping.

10. A method according to any preceding claim, in which one or both second joint surfaces are partially mitred.

11. A method of manufacturing a PVC window frame according to any preceding claim, in which one or both wider jambs has a partially mitred inner face corresponding to a respective second joint surface so as to abut against the second joint surface.

12. A method of manufacturing a PVC window frame according to claim 11, in which the angled part of the partially mitred face of the wider jamb and the second joint surface do not extend to the outermost face of the window frame.

13. A method of manufacturing a PVC window frame according to any preceding claim, in which a cut substantially parallel to the transom is made in the transom and upper jamb frame which extends inwardly until it meets the mitred part of the partially mitred face.

14. A method according to claim 13, in which the cut is substantially horizontal and the jambs are substantially vertical.

15. A method of manufacturing a PVC window frame according to any preceding claim, in which the upper jambs are the narrower jambs and create a recess into which an imitation sash window may be fitted of suitable thickness to present a continuous vertical sightline on the inner window frame.

16. A method of manufacturing a PVC window frame according to any preceding claim, in which the imitation moving sash part of the window is located in the lower part, the lower jamb being narrower than the upper jamb and the transom being wider than the respective lower jambs.

17. A window frame manufactured according to any preceding claim.

18. A PVC window frame substantially as hereinbefore described with reference to and/or as illustrated in figures 1 to 3, 7 and 8.

19. A method of manufacturing a PVC window frame substantially as hereinbefore described and with reference to and/or as illustrated in figures 1 to 3, 7 and 8.