EP0381425A2

EP0381425A2 - Elongate flexible elements particularly for use as glazing strips

Info

Publication number: EP0381425A2
Application number: EP90300922A
Authority: EP
Inventors: David Michael Deacon
Original assignee: RAVENSCROFT PLASTICS Ltd
Current assignee: RAVENSCROFT PLASTICS Ltd
Priority date: 1989-02-01
Filing date: 1990-01-30
Publication date: 1990-08-08
Also published as: GB2227781B; GB2227781A; GB8902188D0; EP0381425A3; GB9002097D0

Abstract

An elongate flexible element for use as a glazing gasket comprises a main body (10) integrally formed with a tear-off strip (15) extending along the length thereof, the tear-off strip being connected to the main body (10) by a zone which may be readily ruptured to enable the strip to be detached from the main body. The effective thickness of the glazing strip may therefore be reduced, if required, by removing the tear-off strip (15). Adjacent the rupturable zone there is integrally formed with the gasket an elongate strip (18) of material which is harder and less flexible than the material of the main body and tear-off strip, so as to facilitate the tearing-off of the strip (15).

Description

The invention relates to elongate flexible elements, particularly but not exclusively for use as glazing strips in windows or doors, whether such windows/doors are made of metal, wood, UPVC, or any combination thereof.
Elongate flexible glazing strips are inserted into the spaces between the edge portions of the window pane (or other panel) and the walls of the frame members, usually channel-sectioned, into which the edges of the panel are engaged. The strips hold the panel firmly in position and also prevent the ingress of air water and dirt.
It has been found, however, that conventional designs of strip can accommodate only small variations in the thickness of the panel. If the panel is thick, so that the space between the panel and the frame member is small, it may be difficult to introduce the strip into the space and, in any case, the strip is then likely to be overstressed. On the other hand, if the panel is thin and the space too large, there may not be sufficient grip between the strip and the panel to ensure that the panel is firmly held in place. For these reasons, it was previously necessary for a different size of strip to be manufactured for each particular thickness of panel with which it was to be used.
In an endeavour to overcome this problem there has been developed a form of flexible glazing strip comprising a main body which is integrally formed with a tear-off strip of material extending along its length and located in, or foldable to, a position where it overlies part of the main body so as to increase its effective thickness, the tear-off strip being connected to the main body by a zone of material which is rupturable to enable the strip to be detached from the main body. The incorporation of the tear-off strip enables the thickness of the strip to be adjusted, to a certain extent, to the thickness of the space into which it is to be fitted.
An example of a flexible element having such a tear-off strip is described and claimed in our British Patent No. 2142370. The strip described in that patent specification is generally channel-shaped in cross-section but the principle of providing a tear-off strip is also applicable to other shapes of element.
Existing designs of such elements are satisfactory with the materials hitherto used for their manufacture, such material often being PVC. Recently, however, higher trade standards have applied to the material used for such strips and plain PVC is no longer acceptable. In order to comply with trade requirements it has become increasingly necessary for the elements to be formed from more resilient materials, such as PVC-nitrile, which is PVC having a nitrile rubber content (ideally about 30% nitrile rubber). Thermo-plastic rubber (tpr) is also used. Since these materials are more reslient than PVC, in existing designs of elongate elements incorporating tear-off strips difficulty has been experienced in tearing off the strips. Due to restraints in the design of extrusion dies and in the manufacturing process, there is a limit, in practice, to how thin the rupturable zone between the tear-off strip and the main body of the element can be, and with the new tougher materials it is difficult to provide a zone which can be readily ruptured and yet which provides sufficiently positive attachment of the strip to the main body in the case where the tear-off strip is to be retained. The present invention sets out to provide, in one aspect thereof, an improved form of strip which may overcome this problem.
The invention is also applicable to other kinds of elongate glazing elements which do not normally incorporate tear-off strips as described above. In one common form of elongate flexible glazing gasket the main body of the gasket is inserted between a rigid glazing bead and the pane of glass of the window or door. The main body of the gasket is formed at its upper end with an enlarged flange which lies outside the space between the glazing bead and the glass and projects laterally from each side of the main body so as to overlie the surface of the bead and the surface of the glass to a certain extent. The glazing bead and gasket are usually on the external side of the window, and if the gasket is removed it is possible then to remove the glass from the window (or door) and gain unauthorised access to the building in which the pane of glass is fitted.
In an attempt to prevent such unauthorised removal of the gasket, the main body of the gasket is normally formed along its length with a laterally projecting location piece which engages within a groove in the glazing bead. This makes it more difficult to remove the gasket. However, in practice it is still possible forcibly to prise the gasket out.
According to another aspect of the present invention, therefore, the enlarged upper flange of such a gasket is connected to the main body by a rupturable zone so that if an attempt is made to remove the gasket forcibly by pulling or prising the exposed flange, the flange will simply act like a tear-off strip and will separate from the main body of the gasket, leaving the main body still wedged between the glazing bead and the glass panel. With the exposed flange of the glazing strip thus removed, it becomes virtually impossible then to remove the rest of the gasket, which thus continues to retain the window pane in place.
According to the invention there is provided an elongate flexible element comprising a main body which is integrally formed with a tear-off strip of material extending along the length thereof, the tear- off strip being connected to the main body by a zone of material which is rupturable to enable the strip to be detached from the main body, and there being provided along and adjacent said rupturable zone an elongate strip of material which is harder and less flexible than the material in said zone, so as to facilitate the tearing off of the tear-off strip.
Said elongate strip of harder and less flexible material may comprise part of the tear-off strip itself, said rupturable zone being located between the harder strip and the main body of the flexible element. Alternatively the strip may comprise part of the main body of the flexible element, said rupturable zone being located between the further strip and the tear-off strip. Preferably the harder elongate strip extends substantially through the whole thickness of the tear-off strip or the main body of the flexible element.
The main body of the flexible element, and the tear-off strip, may be formed, for example, from PVC-nitrile or thermoplastic rubber and the strip of harder and less flexible material may be formed from semi-rigid PVC.
In some embodiments of the invention the tear-off strip may be located in, or foldable to, a position where it overlies part of the main body so as to increase the effective thickness of at least a portion thereof. In this case the tear-off strip may be of such a width as to overlie at least a major portion of a side of the main body of the flexible element.
In one embodiment of the invention the main body of the elongate flexible element is generally wedge-shaped in cross-section, the tear-off strip being connected, by said rupturable zone, to a portion of the main body at or near the apex of the wedge-section. The main body of the element may be formed with a notch extending along one side face thereof, the tear-off strip being connected to the side face of the main body which is opposite to said notch.
In a different embodiment the main body of the element is generally channel-shaped in cross-section, the tear-off strip being connected, by said rupturable zone, along the free extremity of at least one of the side walls of the channel section so as to lie, or be foldable to lie, alongside said side wall and thereby increase the effective thickness of at least a portion thereof. Alternatively the tear-off strip may be connected, by said rupturable zone, along the junction between at least one side wall and the web portion of the channel-section.
In a further embodiment of the invention the tear-off strip comprises an enlarged flange, and said harder and less flexible strip is located at the junction of the flange with the main body of the element.
The following is a more detailed description of embodiments of the invention, reference being made to the accompanying drawings in which:

Figure 1 is a sectional view of an elongate flexible glazing element having a tear-off strip,
Figure 2 is a sectional view of a similar flexible glazing element in accordance with the present invention,
Figure 3 is a similar view of an alternative form of element in accordance with the invention,
Figure 4 is a sectional view of the glazing element of Figure 1 modified in accordance with the present invention,
Figures 5 and 6 are sectional views of channel-shaped glazing elements according to the invention,
Figures 7 and 8 are sectional views of flexible glazing elements the enlarged flanges of which are formed as tear-off strips to prevent unauthorised removal of the elements, and
Figure 9 is a sectional view of a still further form of glazing element in accordance with the invention.

Figure 1 shows in enlarged section a known form of elongate flexible glazing element incorporating a tear-off strip. The element is a continuous extrusion of constant cross-section and is formed from PVC, PVC-nitrile or similar resiliently flexible material.
The main body 10 of the element is generally wedge-shaped in cross-section, the opposed sides 11, 12 of the section being concave and convex respectively. The convex side 12 of the main body is formed with a notch 13 which, in use, fits over an inwardly projecting bead or flange on a side wall of the frame member, usually channel-sectioned, with which the element is used. In well known manner the element is forced between the surface of the glass panel and the wall of the channel, and the left hand side 11 of the element bears against the surface of the glass panel.
Co-extruded within the main body 10 of the element is a portion 14 of harder and less flexible material which is formed, for example, from semi-rigid PVC. This serves to prevent stretching of the element longitudinally and may also be colour coded to assist identification of different styles of element.
A tear-off strip 15 is integrally formed with the main body 10 of the element on the concave side 11, and is connected to the main body 10 by a thin membrane portion 16 near to the apex of the wedge-section. The tear-off strip 16 may be left in place or removed by rupturing the thin membrane portion 16, according to the required thickness of the element.
As previously mentioned, with certain materials now preferred for the manufacture of such glazing elements, such as PVC-nitrile, difficulty may be encountered in extruding a suitable reduced thickness membrane portion 16. This portion must be thick enough to ensure that the strip 15 does not become detached if it is required to be kept in place, and yet thin enough to permit ready detachment of the tear-off strip 15 if it is not required. With the tougher materials now in use a thin membrane is necessary to permit easy tear-off, but this is a difficult to extrude with accuracy.
The modified glazing element according to the invention shown in Figure 2 is generally similar in overall cross-sectional shape to the element of Figure 1 and similar parts therefore have the same reference numerals. In this embodiment, however, the harder and less flexible insert 17 is embedded at the right hand surface of the main body 10 in a position to provide the lower surface of the notch 13.
The tear-off strip 15 is connected to the main body 10 by a further elongate strip 18 of material which is harder and less flexible than the material of the main body 10 and tear-off strip 15. For example the strip 18 may be formed from semi-rigid PVC. The strip 18 is co-extruded with the strips 15 and main body 10 using conventional techniques for co-extrusion.
In the arrangement shown, the strip 18 extends through the whole thickness of the tear-off strip 15 but it might equally well be embedded at least partly in the strip 15 so as to extend through only part of the thickness thereof. Due to the difference in strength between the strip 15 and the strip 18 the tendency of the tear-off strip to separate from the main body when pulled is enhanced. Depending on the shapes of the components of the element, the tear-off strip 15 may rupture at its junction with the harder strip 18, leaving the harder strip still adhering to the main body 10, or the rupture may occur between the harder strip 18 and the main body 10. The rupture zone may thus be considered as part of the main body or as part of the tear-off strip.
The alternative arrangement shown in Figure 3 is somewhat similar to the arrangement of Figure 2, insofar as the tear-off strip 15 and co-extruded strip 18 are concerned. However, in the form of element shown in Figure 3 the main harder and less flexible insert 19 is wholly embedded in the main body of the strip so that layers 20 of the main body material extend along the upper and outer surfaces of the insert. Accordingly, the insert 19 is positioned to reinforce the lower wall of the notch 13 but does not itself form part of the wall of the notch.
In the arrangements shown the harder strip 18 might be regarded as part of the strip 15 since it projects from the main body 10, but in alternative arrangements the hardened strip may be embedded in the main body 10 itself, at or adjacent the surface thereof.
Figure 4 shows the application of the invention to the prior art glazing element shown in Figure 1 in which the portion of harder and less flexible material 14 within the main body 10 is circular in cross-section. As in the arrangements of Figures 2 and 3, the tear-off strip 15 is connected to the main body 10 by a further elongate strip 18 of material which is harder and less flexible than the material of the main body 10 and tear-off strip 15.
Figures 1-4 show a particular wedge-shaped type of glazing element. However the invention is equally applicable to other flexible elongate elements incorporating tear-off strips and Figures 5 and 6 show the application of the invention to generally channel-sectioned glazing gaskets of the kind described in British Patent No. 2142370.
Referring to Figure 5, the gasket 20 is an extrusion of suitable resiliently flexible plastics/rubber material, and is generally channel-sectioned, having side walls 21 and 22 joined by a web portion 23.
The outer surface of each side wall 21 and 22 is formed with two projecting lips 24 extending longitudinally of the gasket, the lips being inclined away from the web portion 23. The free edges of the side walls 21 and 22 of the gasket are each formed with an outwardly projecting longitudinal flange 25 and an inwardly projecting lip 26.
In use, the gasket 20 embraces and extends around the peripheral edges of a glass panel (not shown). The gasket 20 is first fitted around the glass panel and the peripheral edge of the panel, carrying the gasket, is then inserted in channel-section frame members.
To enable the gasket of Figure 5 to be used with glass panels of varying thickness, it is provided with an auxiliary tear-off strip 29 which extends longitudinally of the gasket and is integrally formed with it, being connected to the upper extremity of the left hand side wall 21 of the main channel-section (as viewed in Figure 5).
In accordance with the present invention, the tear-off strip 29 is connected to the upper edge of the side wall 21 by a strip 30 of a material which is harder and less flexible than the material of the tear-off strip 29 and the main body of the gasket. For example, as before, the strip 30 may be formed from semi-rigid PVC and is co-extruded with the tear-off strip 29 and main body 20 using conventional techniques for co-extrusion. The strip 30 extends through the whole thickness of the tear-off strip 29 but it might equally well extend through only part of the thickness thereof.
As in the previous arrangements, due to the difference in strength between the strip 30 and the surrounding zones of material, the tendency of the tear-off strip 29 to separate from the main body when pulled is enhanced. In the arrangement shown in Figure 5 the tear-off strip 29 will tend to rupture at its junction with the harder strip 30, leaving the harder strip still adhering to the rest of the gasket.
When the tear-off strip 29 is left in position and is folded flat against the internal surface of the side wall 21 it reduces the effective internal width of the channel so that the gasket will receive snugly the peripheral edge of a thinner glass panel. If however it is desired to use the gasket with a thicker glass panel, then the strip 29 is removed by tearing it off.
It will be appreciated that a second tear-off strip can be connected in similar fashion to the right hand side wall 22, and this then provides even greater possible variation in the effective width of the channel since one or both tear-off strips can be removed.
Figure 6 shows a further channel-section glazing gasket basically similar to that shown in Figure 5, but in this case the tear-off strips 29 are connected, through the harder strips 30, at the junctions between the side walls 21 and 22 respectively and the web portion 23. In this case the tear-off strips are folded to overlie the outer surfaces of the side walls. Again, one or both tear-off strips may be removed. In an alternative arrangement, not shown, only a single tear-off strip is provided adjacent one of the two side walls.
Figure 7 shows a different form of elongate flexible glazing gasket 31. In this case the main body 32 of the gasket is formed on one side with a retaining portion 33 which is arrowhead-shaped in cross-section and is received within a correspondingly shaped recess 34 in a rigid metal or plastics glazing bead 35. The opposite side of the main body 32 is formed with two projecting inclined lips 36 which, in use, bear against the pane of glass to be held in position by the glazing bead.
Integrally formed on the upper end of the main body 32 is an enlarged flange 37 which projects laterally to both sides of the main body portion 32. When the gasket is in position between the glazing bead 35 and the window pane, part of the enlarged flange 37 overlies the upper edge of the glazing bead 35 and the rearward part of it bears against the surface of the pane of glass.
The enlarged flange 37 is connected to the main body 32 of the gasket by a wedge-sectioned strip 38 which is formed from a material which is harder and less flexible than the rest of the gasket. For example it may be formed of semi-rigid PVC.
When the gasket is in use it provides firm and watertight engagement between the glazing bead 35 and the pane of glass. It also prevents removal of the pane of glass from the window. Any unauthorised person trying to remove the pane of glass to gain access through the window must first remove the gasket 31 and this would normally be done by pulling on the exposed flange 37, from one end, and trying to strip the gasket out of the gap between the glazing bead 35 and the pane of glass. In accordance with the present invention, however, the presence of the harder strip 38 means that the enlarged flange 37 is, in effect, a tear-off strip since the presence of the harder strip provides a zone of relative weakness adjacent the strip, causing the enlarged flange 37 to become detached from the rest of the gasket if it is pulled.
Figure 8 shows another form of flexible glazing gasket 39 having similar characteristics to the gasket 31 of Figure 7. In this case the main body 40 of the gasket comprises two limbs 41 and 42 arranged in an inverted "V" configuration and one of the limbs 42 is received in a slot 43 in a metal or plastics elongate glazing bead 44. At the upper end of the gasket 39 an enlarged flange 45 is connected to the main body 40 of the gasket by a strip 46 of harder and less flexible material. As in the previous arrangement, any forcible attempt to remove the gasket 39 from between the glazing bead and the pane of glass will simply result in the enlarged flange 45 being torn from the rest of the gasket.
Figure 9 shows in section a different form of glazing gasket 47 comprising a main body portion 48 having oppositely inclined flanges 49 on its upper and lower edges respectively, and an intermediate upwardly inclined compression fin 50. Projecting from the opposite side of the main body 48 is a generally T-shaped retaining strip 51, which in use, will be received in a correspondingly shaped slot in a metal glazing bead (not shown). In order to reduce the effective thickness of the gasket, if required, the compression fin 50 is in the form of a tear-off strip which may be removed from the main body of the gasket. To facilitate this removal the compression fin 50 is connected to the main body 48 by a wedge-sectioned strip 52 of a material which is harder and less flexible than the material of the main body of the gasket. In certain cases more than one compression fin may be used on such a gasket. As shown, the T-shaped retaining strip 51 is also made of a material which is harder and less flexible than the main body of the gasket, to enhance its retaining effect.

Claims

1. An elongate flexible element comprising a main body (10) which is integrally formed with a tear-off strip (15) of material extending along the length thereof, the tear-off strip being connected to the main body by a zone of material which is rupturable to enable the strip to be detached from the main body, characterised in that there is provided along and adjacent said rupturable zone an elongate strip (18) of material which is harder and less flexible than the material in said zone, so as to facilitate the tearing off of the tear-off strip.

2. An element according to Claim 1, characterised in that the harder elongate strip (18) extends substantially through the whole thickness of the tear-off strip (15) or the main body (10) of the flexible element.

3. An element according to Claim 1 or Claim 2, characterised in that the main body (10) of the flexible element, and the tear-off strip (15), are formed from PVC-nitrile or thermoplastic rubber and the strip (18) of harder and less flexible material is formed from substantially semi-rigid PVC.

4. An element according to any of Claims 1 to 3, characterised in that the tear-off strip (15) is located in, or is foldable to, a position where it overlies part of the main body (10) so as to increase the effective thickness of at least a portion thereof.

5. An element according to Claim 4, characterised in that the main body (10) of the elongate flexible element is generally wedge-shaped in cross-section, the tear-off strip (15) being connected, by said rupturable zone, to a portion of the main body at or near the apex of the wedge-section.

6. An element according to Claim 5, characterised in that the main body (10) of the element is formed with a notch (13) extending along one side face thereof, and characterised in that the tear-off strip (15) is connected to the side face of the main body (10) which is opposite to said notch (13).

7. An element according to Claim 4, characterised in that the main body (20, Fig. 5) of the element is generally channel-shaped in cross-section, the tear-off strip (29) being connected, by said rupturable zone, along the free extremity of one side wall (21) of the channel section so as to lie, or be foldable to lie, alongside said side wall (21) and thereby increase the effective thickness of at least a portion thereof.

8. An element according to Claim 4, characterised in that the main body of the element (Fig. 6) is generally channel-shaped in cross-section, the tear-off strip (29, Fig. 6) being connected, by said rupturable zone, along the junction between one side wall (21) and the web portion (23) of the channel-section so as to lie, or be foldable to lie, alongside said side wall (21) and thereby increase the effective thickness of at least a portion thereof.

9. An element according to Claim 7 or Claim 8, characterised in that there are provided two tear-off strips (29, Fig. 6), each having an associated rupturable zone and elongate strip (30) of harder and less flexible material, said strips (29) being symmetrically connected to the respective side walls (21, 22) of the channel-section.

10. An element according to any of Claims 1 to 3, characterised in that the tear-off strip comprises an enlarged flange (37, Fig. 7), and said harder and less flexible strip (38) is located at the junction of the flange (37) with the main body (32) of the element.