GB2598976A

GB2598976A - Glazing Bead

Info

Publication number: GB2598976A
Application number: GB2103333.7A
Authority: GB
Inventors: Kernaghan Ian
Original assignee: Eurocell Profiles Ltd
Current assignee: Eurocell Profiles Ltd
Priority date: 2021-03-10
Filing date: 2021-03-10
Publication date: 2022-03-23
Anticipated expiration: 2041-03-10
Also published as: GB202103333D0; GB2598976B

Abstract

A generally L shaped glazing bead 60; with a body or leg part (61 fig.6) which bears against a pane 80, and a foot or anchorage part (62 fig.6) which is anchored into a channel 72 in a frame 70, and where the foot has a recess in which a lip 75 of the channel sits and also a protuberance (69 fig. 6) that fits in a recess in the wall of the channel. The protuberance may be a strip and its cross-section may be formed from many shapes such as triangular, wedge shaped or square for example. The protuberance may be tapered to resist rotational movement of the glazing bead. The bead may be hollow, and the leg part may be a modified rectangle in cross-section. The leg or body part may have a sealing fin and the foot may be tapered. A frame with a channel with a lip at its mouth is claimed and a frame with the defined glazing bead is also claimed.

Description

Glazing bead Field

The present invention relates to a glazing bead for securing a pane or glazed unit in a window frame.

Background

Glazing beads are known for use in PVCu window systems which are of a strip form made, such as by extrusion, from a plastics material. Such a glazing bead attaches to a window frame and bears on a pane or glazed unit to secure the pane or glazed unit to the window frame. An anchorage portion of the glazing bead attaches to the window frame to locate the bead in position on the frame, and a body portion bears on the pane or glazed unit and presents a bevelled external trim surface sloping between the pane or glazed unit and the frame.

An example of one known glazing bead of the kind described is shown in Figures 1 and 2 of the accompanying drawings. This glazing bead 1 comprises a hollow body portion 2 of a right-angled triangular cross section having a base wall 3, perpendicular wall 4 and hypotenuse wall 5, and an anchorage portion in the form of an angled rib 6 projecting from the base wall 3, near an outer corner 7 of the body portion. The hypotenuse wall 5 presents a bevelled external trim surface 8 of the glazing bead. Flexible sealing fins 9 project from an inner corner 10 of the body portion. As shown, the glazing bead is attached to a window frame 11 by engagement of the angled rib 6 in a longitudinal locating channel 12 extending along the window frame, the base wall 3 resting on the mouth of the locating channel such that the perpendicular wall 4 lies flush with a pane or glazed unit 13 located in the window frame. The sealing fins 9 seal on the adjacent surface of the pane or glazed unit 13.

The angled rib 6 is pushed into the locating channel so that its extremity 14 locates in a notch 15 in a bottom corner of the channel, and a root part 16 of the angled rib abuts against a lip 17 at the diagonally opposite side of the mouth of the channel, thereby jamming the angled rib in the channel so as to hold the glazing bead in place on the window frame to secure the pane or glazed unit to the frame. The glazing bead is easily fitted to the window frame for use.

It is common to attach the glazing bead to the window frame at the channel 12, without the pane or glazed unit in place, for transit of the window frame to the site where the window is to be fitted. A problem is that without the pane or glazed unit in place for the body portion of the glazing bead to bear upon, the bead may readily rotate relative to the window frame, as shown in Figure 2, under movement of the frame during transit, or by being knocked, and dislodge the angled rib from the channel, so that the glazing bead becomes detached from the window frame.

GB2385878 (another known glazing bead) addresses this problem. In particular, GB2385878 discloses a glazing bead of a generally L-shaped cross-section comprising a leg part which forms a body portion of the glazing bead to bear on a pane or glazed unit and a foot part which forms an anchorage portion of the glazing bead to engage as a force fit in a locating channel of a window frame, and a heel part at or adjacent to which is a heel recess to receive a lip of the mouth of the channel, whereby withdrawal of the anchorage portion from the locating channel is resisted. The force fit solves the problem of the bead rotating and becoming detached, particularly in transit and when the frame is not glazed.

Figures 3a and 3b show a known frame 30 and a known bead 32 according to GB2385878.

Generally, PVCu window frames are glazed from the inside (e.g., from inside a building) for security reasons. However, there remains a problem because burglars use tools to force a way through the front of panels (accessible from outside the building) in a way that enables them to "pop" the bead on the inside. Therefore, even the more securely attached glazing bead 32 of GB2385878 may be popped out of its frame by forcing entry into a vulnerable part of the installation and levering out the bead from the frame. Figures 4a to 4e illustrate this. A knife (or similar tool) 40 can be used to open up an unauthorised access opening in one side of the frame, which is usually made from PVCu. The one side of the frame is usually arranged to be integrally formed without any beading and may be configured, in use, to face outwardly from a building; the other, opposite, side of the frame is configured to face inwardly to a building.

As illustrated in Figures 4b to 4e, a lever tool (such as a screwdriver 42) may be inserted through the unauthorised access opening to bear against a surface of the leg part of the bead of GB2385878 and then manipulated to apply a force on the bead to pop it out of engagement with the frame by popping the lip of the mouth of the frame channel out of engagement with the heel recess.

To obviate this flaw, as shown in Figure 5, it is known for an installer to insert glass clips 50 in the frame at locations that prevent the lever tool having access to the bead from the one side of the frame. Usually, a minimum of four clips are used per double glazed unit. As can be seen in Figure 5, a base plate 52 is typically inserted into a frame channel in which the glazed unit is to be received, and the glass clips are attached thereto. The glass clips 50 provide a physical barrier to a tool reaching through from an unauthorised access opening in the one side of the frame across to the bead 32.

The inventors have realised that a securely attached glazing bead can be provided more efficiently and have created the claimed solution.

Summary

According to a first aspect of the present invention, there is provided a glazing bead as claimed in claim 1. According to a second aspect of the present invention there is provided a frame as claimed in claim 17.

According to a third aspect of the present invention there is provided in combination a window frame according to the second aspect and a glazing bead according to the first aspect Advantageously, resource is saved, and the glazing installation method is simplified compared to the known solution shown in Figure 5.

The resistance to withdrawal of the anchorage portion from the channel by the interengagement between the retaining protuberance and the anchorage wall recess enables the glazing bead to be securely retained to the window frame to which it is fitted even in the event of an unauthorised attempt to remove the bead from the locating channel (i.e., as described in relation to Figures 4a to 4e) and without the need for glass clips or any other physical barrier between the outside frame member and the bead. For the avoidance of doubt, the bead of this invention can be used with glass clips (or another such physical barrier) of the type previously described to provide even further security.

Although the invention is primarily described in detail in relation to window glazing beads and frames, it is applicable to all types of installations. The invention can be used with any known types of beads and frames -e.g., the frame member may be a door frame, a window frame, an outer-frame Z, T, sash or similar as would occur to the person of skill in the art.

Optional features of the invention are as claimed in the dependent claims -various advantages are thereby provided as discussed in the detailed description. Any of these optional features may be combined with any other of the optional features as will be appreciated by those skilled in this art.

Brief Description of Drawings

Embodiments will now be described by way of example only with reference to the accompanying drawings, in which: Figures 1 and 2 show views of a first prior art glazing bead and frame; Figures 3a and 3b show views of a second prior art glazing bead and frame; Figures 4a to 4e illustrate an unauthorised entry method for the second prior art glazing bead and frame; Figure 5 shows the second prior art glazing bead and frame in use with a securing clip; Figure 6 shows a cross-section through a glazing bead according to a first aspect of the invention; Figure 7 shows a cross-section through a frame according to a second aspect of the invention; Figure 8 shows a cross-section through the glazing bead of the first aspect and the frame of the second aspect in use with a glazed unit; and Figures 9a to 9e show cross-sections through glazing bead and frame combinations according to further aspects of the invention.

Description of Embodiments

The exemplary embodiments described in the detailed description and claims are not meant to be limiting. Other embodiments may be used, and other changes may be made, without departing from the scope of the invention. Various embodiments are described. The specific embodiments are not intended as an exhaustive description or as a limitation to the broader discussed and claimed aspects. Features described in conjunction with a particular embodiment are not necessarily limited to that embodiment and can be incorporated into any other embodiment(s). Protection afforded by any applicable doctrine of equivalents is retained to its fullest extent.

Terms such as up, down, top, bottom, left, right, inner, outer, vertical, upstanding etc. have been used to simply and clearly describe the invention. These terms are not to be interpreted in a manner that would be limiting. The person skilled in the art will envisage other suitable embodiments within the scope of the invention.

Referring to Figures 6 to 8, a glazing bead 60 according to one embodiment is shown which is hollow and of a generally L-shaped cross-section comprising a body portion 61 and an anchorage portion 62 formed respectively by a leg part and a foot part of the L-shape with a heel part 63 therebetween. The glazing bead 60 is formed, as by extrusion, from a plastics material such as used for known glazing beads. The hollow form is desirable, in this example, for saving of material and also because an increased tolerance band can be provided in the manufacture of the glazing bead for achieving satisfactory functioning and location of the glazing bead on a frame, such as a window frame.

The body portion 61 is of a modified rectangular form in cross-section with the anchorage portion 62 projecting from one end of the body portion. One side wall 64 of the body portion presents a bevelled external trim surface of the glazing bead. An opposite end wall 65 of the body portion is inclined at an acute angle to the side wall 64. A flexible sealing fin 651 projects from the end wall 65 in alignment with the trim surface presented by the side wall 64.

The anchorage portion 62 is of a generally arrow-head form in cross-section, tapering away from the body portion 61. The anchorage portion 62, formed by the foot part, has a dorsum wall 67 at the inside of the angle between the anchorage and body portions. The body portion 61 has another side wall 66 at the inside of the angle between the body and anchorage portions. The dorsum wall 67 extends from the side wall 66 at an obtuse angle. The anchorage portion 62 also has a bottom wall 68 that extends at an acute angle from the dorsum wall 67 to the heel part 63.

In this embodiment, the dorsum wall 67 extends simply in a straight line from the side wall 66. In other embodiments (not shown), the dorsum wall 67 has an inset section next to the body portion, behind the arrow-head form (similar to that seen in Figures 3 and 4 of 0B2385878). Such an inset section can allow some bodily tilting movement of the glazing bead in a direction towards the centre of the window frame. In such embodiments, the retaining protuberance may be longer than in this embodiment (i.e., it may be an elongate protuberance).

In the anchorage portion 62, at the heel part 63 of the L-shape of the glazing bead 60, is a heel recess 631 in the form of a groove of part-circular cross-section. One side of the heel recess merges with the side wall 64 of the body portion 61 at a bevelled edge 641.

The foot part further comprises a retaining protuberance 69 arranged to be received in an anchorage wall recess in a wall of a corresponding locating channel of a frame as described in further detail below. Engagement between retaining protuberance 69 and the anchorage wall recess resists withdrawal of the anchorage portion from the locating channel.

In this embodiment, the retaining protuberance 69 protrudes from the dorsum wall 67. The protuberance protrudes from the dorsum wall in substantially the same linear direction as the heel recess 631 in this example. The retaining protuberance is located at a mid-part of the dorsum wall 67 near the side wall 66 of the body portion. In this embodiment, the retaining protuberance 69 is a protruding elongate strip that protrudes from the dorsum wall 67. The protruding strip and the bead are generally elongate and of a form that allow for easy manufacturing via an extrusion process. In this embodiment, the retaining protuberance is of part-circular section, as seen in Figures 6 and 8.

The glazing bead 60 is fitted for use to a PVCu window frame 70, as shown in Figures 7 and 8, to secure a sealed double glazed unit 80 in the frame 70. The glazing bead 60 attaches to the frame by engagement of the anchorage portion 62 in a longitudinal locating channel 72 formed in the frame, parallel to the glazed unit 80 to be secured to the frame. The channel 72 is defined by an anchorage wall that generally matches the shape of the anchorage portion 62.

The channel 72 has a mouth 74 formed with an inturned lip 75 along the side of the channel remote from the glazed unit. The lip 75 restricts the mouth 74 and the anchorage portion is dimensioned at the widest part of the arrow-head form of its cross-section to be an interference fit in the mouth. It is necessary, therefore, for the anchorage portion to be forced through the mouth by pushing or knocking the glazing bead into place. The material of the glazing bead has sufficient resilience to allow the distortion of the widest part of the anchorage portion for it to pass through the mouth. Once the widest part has passed through the mouth the resilience of the material restores the anchorage portion to its original shape with the result that there is effectively a snap engagement of the lip 74 in the heel recess 631 of the heel part 63 of the glazing bead. The dimensions and form of the anchorage portion relative to the channel 72 are also such that when that snap engagement is achieved the anchorage portion substantially fills the channel below the level of the lip 75. The anchorage portion is consequently positively retained and located in the channel, and the glazing bead is held securely on the window pane.

With the anchorage portion properly secured in the channel the bevelled edge 641 of the side wall 64 of the body portion 61 bears on top of the lip 75, as shown in Figure 8. This urges the body portion 61 to bear on the glazed unit 80 to secure it to the window frame, and the sealing fin 651 to seal on the surface of the glazed unit 80.

A section of the anchorage wall extends down from one side of the mouth 74 near the lip 75. Another opposed section 77 of the anchorage wall extends down from an opposite side of the mouth 74. In use, the lip side is arranged to be presented closer to the inside of a building where the frame is to be installed, and the opposite side is arranged to be closer to the exterior. In this embodiment, an anchorage wall recess 79 is formed in the opposed section 77 of the anchorage wall of the locating channel. The anchorage wall recess 79 is configured to engage with the retaining protuberance of the bead to obstruct removal of the anchorage portion from the locating channel, especially in the event of attack from an exterior of the building (of the type previously described in reference to Figures 4a to 4e). In other embodiments, the anchorage wall recess is defined by an anchorage wall step or other formation on or in the anchorage wall which has the effect of creating a recess for interengagement with the retaining protuberance of the glazing bead.

In this example, the anchorage wall recess 79 is near the mouth 74 of the channel 72, in an upper part of the wall section 77 in this embodiment. In other embodiments, the anchorage wall recess may be located elsewhere. In some embodiments, there may be multiple pairs of corresponding retaining protuberances

S

and anchorage wall recesses. For example, an anchorage wall recess may be provided instead or additionally elsewhere in the wall section 77. Or, an anchorage wall recess may be provided instead or additionally not in the wall section 77, but in a different section of the anchorage wall, such as on a bottom section of the anchorage wall, where the bottom section extends between the opposed section 77 and the wall section that extends down from near the lip 75.

Engagement between the retaining protuberance and the anchorage wall recess resists withdrawal of the anchorage portion from the locating channel when under attack from the exterior (e.g., via application of a translational or rotational force to a front/exterior side of the leg part, such as by exerting relevant pressure to side wall 66 of the bead 60).

Optionally, and advantageously, in this embodiment, the anchorage wall recess is not too high on the wall 77 (i.e., not too close to the mouth 74 of the channel) such that it might create a structural weakness that could cause the lip to snap off during an unauthorised access attempt. Given the teaching of this document, the skilled person will be able to ascertain a threshold distance that would be too close to the mouth 74 by experimentation.

The dorsum wall 67 of the bead 60 is opposed to the heel part -in this example, the protuberance protrudes from the dorsum wall in substantially the same linear direction as the heel recess 631 (and therefore the frame lip 75 when it is located in the heel recess in use).

As a result, the engagement between the heel recess 631 and the frame lip 75, and the retaining protuberance 69 and the anchorage wall recess 79 work in combination to obstruct removal of the anchorage portion from the locating channel. The malicious activity being guarded against encourages lifting and levering of the bead out of the locating channel as seen in Figures 4a to 4e. The aligned fit of the retaining protuberance in the anchorage wall recess resists such lifting and levering particularly well.

In this example, the anchorage wall recess 79 has a generally rectangular cross section (see Figure 7). The retaining protuberance 69 and anchorage wall recess 79 are formed so as to interengage with the with a snap or notch-like action. This adds to the security of the retention of the anchorage portion in the channel of the window frame. It also gives a positive indication to the fitter of the glazing bead of proper engagement of the anchorage portion in the channel. In this example, the profile of the retaining protuberance 69 and anchorage wall recess 79 closely match.

Cross section profiles of pairs of retaining protuberances and anchorage wall recesses are illustrated in Figures 9a to 9e. These examples are not an exhaustive list -other suitable shapes will be apparent to the skilled person.

The retaining protuberance may be of part-circular section or triangular section, wedge-shape section, trapezoidal section, rectangular section or square section. The anchorage frame recess may be of part-circular section or triangular section, wedge-shape section, trapezoidal section, rectangular section or square section. The profiles of the retaining protuberance and the anchorage frame do not need to be identical. They do need to work together to provide the relevant resistance though.

The engagement between the retaining protuberance and the anchorage frame recess is arranged to: resist withdrawal, via application of a translational or rotational force to a front side of the leg part, of the anchorage portion from the locating channel; allow withdrawal, via application of a translational or rotational force to a rear side of the leg part or the heel part, of the anchorage portion from the locating channel; or aid insertion of the anchorage portion into locating channel; or any combination thereof.

These effects can be further enhanced in some embodiments by the specific shape of the bead or the frame or both.

For example, the retaining protuberance may be a tapered retaining protuberance having a tapered lower face (see Figures 9c, 9d and 9e and to a lesser extent 9a and 9b). Similarly, the anchorage wall recess may be a tapered anchorage wall recess having a tapered lower surface (see Figures 9b and 9d in particular). Such tapered faces and surfaces facilitate disengagement of the retaining protuberance 69 from the anchorage wall recess 79 when a rotational force is applied from the inside of the frame (as described in further detail below, e.g., during intentional withdrawal of the anchorage portion from the locating channel by application, such as via a tool bearing against the heel recess, of a rotational force to a rear side of the leg part -this involves applying a force having a rotational effect in a first rotation direction, e.g., anticlockwise). The frame lip is popped out of the heel recess with little resistance from the engagement between the retaining protuberance and the locating channel wall due to the shape of the lower face of the retaining protuberance or the anchorage wall recess or both. In particular, the lower face of the retaining protuberance is tapered to provide little resistance to this movement, e.g., rotational movement in the anticlockwise direction in this example.

In contrast, for movement in the other direction, i.e., when a clockwise force is experienced, such as when unauthorised access is attempted via a lever tool from the front of the frame, the shape of the upper face of the retaining protuberance or anchorage wall recess or both is such that there is significant resistance to this movement. The upper face is flat and untapered (in this example) and engages solidly with the corresponding surface of the locating channel wall without encouraging any undesirable unengaging sliding movement. In other examples, there may even be a reverse taper such that such unengaging sliding movement is even further resisted.

In general terms, the upper face of the retaining protuberance may be completely untapered or tapers away inwardly, i.e., the retaining protuberance is narrower at the base of the protuberance and broader at its distal end -this profile resists easy withdrawal of the anchorage portion from the locating channel by application of a translational or rotational force to a front side of the leg part.

The lower face of the retaining protuberance tapers away outwardly, i.e., the retaining protuberance is broader at the base of the protuberance and narrower at its distal end -this profile aids withdrawal of the anchorage portion from the locating channel.

The lower face of the retaining protuberance tapers away upwardly, i.e., the retaining protuberance is broader at its upper end and narrower at its lower end -aids insertion of the anchorage portion into locating channel.

Similar profile shapes can be applied to the anchorage wall recess to achieve the same effect.

B

Similar profile shapes can be applied to both the retaining protuberance and the anchorage wall recess to enhance the effect(s).

The glazing bead may be attached to the window frame for transit of the window frame to the site where it is to be fitted before the glazed unit is applied to the frame. Engaged in the channel 72 of the window retaining protuberance and the anchorage wall recess frame the anchorage portion securely retains the glazing bead to the frame in this situation. In embodiments that include an inset section, the inset section may allow some bodily tilting movement of the glazing bead in a direction towards the centre of the window frame.

However, the interengagement between the heel recess and lip (as well as the interengagement between the retaining protuberance and the anchorage wall recess) prevents unintentional separation of the anchorage portion from the channel during transit.

For the fitting of the glazed unit 80 to the window frame, the glazing bead can be released from the frame by manipulating the body portion so as to force the retaining protuberance 69 from the anchorage wall recess 79 and also the heel recess 631 to separate from the lip 75. The release may be assisted by inserting a levering tool into the heel recess between the lip 75 and the bevelled edge 641 to lever the glazing bead so as to separate the heel recess and the lip sufficiently and to remove the retaining protuberance from engagement with the anchorage wall recess for the widest part of the arrowhead form of the anchorage portion to pass out through the mouth of the channel.

Furthermore, if the installed frame and bead are subject to an attack from the other side of the frame (of the type shown in Figures 4a to 4e), then a levering tool bearing against the front side wall 66 of the bead has little effect. The secure engagement between the retaining protuberance 69 and the anchorage wall recess 79 (particularly to resist rotational movement in a direction opposite to that intended to cause release by the levering tool described in the previous paragraph) ensures that the anchorage portion of the bead is retained in the locating channel of the frame. The anchorage portion may still be manipulated out of engagement with the channel from the inside as described previously. In combination, the secure retainment features provide a bead that is able to withstand attack and unintentional withdrawal from its frame.

Various modifications may be made to this invention without departing from its scope.

In other embodiments, instead of the frame lip and heel recess, there may be a different engagement mechanism provided between the bead and the frame for resisting withdrawal of the bead from the frame during transit prior to fitting.

A different specific mechanism for the engagement between the anchorage portion and the locating channel may be provided. Instead of the protuberance being on the bead and the recess in the wall of the locating channel of the frame, the protrusion may be on the frame and the recess in the anchorage portion of the bead.

Claims

Claims 1. A glazing bead of a generally L-shaped cross-section comprising a leg part which forms a body portion of the glazing bead to bear on a pane or glazed unit and a foot part which forms an anchorage portion of the glazing bead to engage as a force fit in a locating channel of a frame, and a heel part at or adjacent to which is a heel recess to receive a lip of the mouth of the channel, whereby withdrawal of the anchorage portion from the locating channel is resisted, and further wherein the foot part comprises a retaining protuberance arranged to be received in an anchorage wall recess in a wall of the locating channel, whereby withdrawal of the anchorage portion from the locating channel is resisted.
2. A glazing bead according to claim 1, wherein the foot part comprises a dorsum part and the retaining protuberance protrudes from the dorsum part.
3. A glazing bead according to any preceding claim, wherein the retaining protuberance is located at an upper part of the wall of the anchorage portion.
4. A glazing bead according to any preceding claim, in which the retaining protuberance is formed so as to interengage with the anchorage wall recess with a snap or notch-like action.
5. A glazing bead according to any preceding claim, in which the retaining protuberance is a protruding strip, optionally protruding from the dorsum part of the foot part.
6. A glazing bead according to any preceding claim, in which the retaining protuberance is of part-circular section or triangular section, wedge-shape section, trapezoidal section, rectangular section or square section.
7. A glazing bead according to any preceding claim, wherein the retaining protuberance comprises a tapered retaining protuberance arranged to: resist withdrawal, via application of a translational or rotational force to a front side of the leg part, of the anchorage portion from the locating channel; allow withdrawal, via application of a translational or rotational force to a rear side of the leg part or the heel part, of the anchorage portion from the locating channel; or aid insertion of the anchorage portion into the locating channel; or any combination thereof.
8. A glazing bead according to claim 7 wherein the tapered retaining protuberance has a tapered lower face, and optionally a non-tapered upper face.
9. A glazing bead according to any preceding claim, which is hollow.
10. A glazing bead according to claim 9, which is hollow at both the body portion and the anchorage portion.
11. A glazing bead according to any preceding claim, in which the body portion is of a modified rectangular form in cross section, the anchorage portion projecting from one end of the cross section and the opposite end being formed to extend parallel to the surface of the pane or glazed unit on which the body portion bears in use of the glazing bead.
12. A glazing bead according to claim 11, in which at least one flexible sealing fin is provided at said opposite end of the cross section of the body portion to seal on the adjacent surface of the pane or glazed unit.
13. A glazing bead according to any preceding claim, in which the anchorage portion is tapered or reduced in section towards its extremity so as to facilitate insertion of the anchorage portion into the channel of the frame to which the glazing bead is fitted for use, and optionally in which the anchorage portion tapers away from the body portion.
14. A glazing bead according to any preceding claim, in which the heel recess is formed so as to interengage with the lip of the mouth of the channel with a snap or notch-like action.
15. A glazing bead according to any preceding claim, in which the heel recess is a groove, optionally of part-circular section, in or adjacent to the heel part of the glazing bead.
16. A glazing bead according to any of claims 1 to 13, in which the heel recess is defined by a step or other formation on or in the glazing bead which has the effect of creating a heel recess for interengagement with the lip of the mouth of the channel.
17. A frame having a locating channel arranged to receive an anchorage portion of a glazing bead according to any preceding claim as a force fit therein, the locating channel formed with a lip at its mouth arranged to be engage with the heel recess of the bead, and an anchorage wall recess in a wall of the locating channel arranged to engage with the retaining protuberance of the bead.
18. A frame according to claim 17, wherein the lip is on one side of the channel and the anchorage wall recess is in a wall on an opposite side of the channel, optionally near the mouth of the channel, and optionally the anchorage wall recess is spaced sufficiently from the mouth of the channel to avoid creating a structural weakness.
19. A frame according to claim 17 or claim 18, in which the anchorage wall recess is defined by an anchorage wall step or other formation on or in the anchorage wall which has the effect of creating a recess for interengagement with the retaining protuberance of the glazing bead.
20. A frame according to any of claims 17 to 19, in which the anchorage wall recess comprises a tapered anchorage wall recess arranged to: resist withdrawal, via application of a translational or rotational force to a front side of the leg part, of the anchorage portion from the locating channel; allow withdrawal, via application of a translational or rotational force to a rear side of the leg part or the heel part, of the anchorage portion from the locating channel; or aid insertion of the anchorage portion into the locating channel; or any combination thereof.
21. A frame according to any of claims 17 to 20 and a glazing bead according to any of claims 1 to 16, the anchorage portion of which is a force fit into the locating channel, wherein the retaining protuberance is arranged to engage with the anchorage wall recess and the heel recess is arranged to engage with the lip of the mouth of the channel to resist withdrawal of the anchorage portion from the channel.
22. A frame and glazing bead according to claim 21, in which the dimensions and form of the anchorage portion relative to the channel are such that when received into the channel the anchorage portion substantially fills the channel below the level of the lip.
23. A frame and glazing bead according to claim 21 or claim 22 wherein the anchorage wall recess is located near the mouth of the locating channel.
24. A frame and glazing bead according to any of claims 21 to 23 in which a wall of the anchorage portion at the inside of the angle between the anchorage and body portions of the glazing bead has an inset section next to the body portion which allows some bodily tilting movement of the glazing bead relative to the frame in the direction of the centre of the frame, whilst unintentional separation of the anchorage portion from the channel is prevented by the interengagement between the heel recess and the lip.