AU2007101213A4 - Security door - Google Patents

Description

AUSTRALIA

-E

FB RICE CO Patent and Trade Mark Attorneys Patents Act 1990 LOCKER GROUP PTY LTD COMPLETE SPECIFICATION INNOVATION PATENT Invention Title: Security door The following statement is a full description of this invention including the best method of performing it known to us:- 2 Cross-Reference to Related Applications d The present application claims priority from Australian Provisional Patent Application No 2007903008 filed on 4 June 2007, the content of which is incorporated C herein by reference.

SField of the Invention C This invention relates to security screens, particularly for a security door but the principals may applied to covering other openings such as windows, or other apertures in buildings which are required to allow authorised access or light in, but to keep intruders out.

Background of the Invention It is well known to provide security screens on doors and windows to prevent break-ins and other unauthorised access by intruders. AU 621246 discloses a window guard for preventing unauthorised authorised access to a building comprising a hinged screen fabricated from a single sheet of metal with cut-outs which allow light in but prevent ingress of intruders.

One common type of security screen comprises a security grill in the form of a grid of intersecting spaced apart bars, typically steel or aluminium.

It is also known to provide screen doors and fly screens on windows to prevent ingress of insects such as flies, blow flies and mosquitoes and the like. Some screen doors provide both functions by superposing a screen comprising a security grill superposed on a fly screen.

AU 754829 discloses a security screen which is formed from a perforated sheet of non-expanded stainless steel sheet which has a plurality of closely spaced apertures punched therein dimensioned to prevent insect access through and past the apertures but which has a thickness sufficient to withstand penetration as a result of impact by blunt objects. In this way, a single element is intended to provide the function of both security and prevention of ingress of insects. However, such a screens has a number of problems including a relatively high cost compared to two component security screens, problems of corrosion, and difficulties in mounting the sheet security screen to a door or window frame.

Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the 3 field relevant to the present invention as it existed before the priority date of each claim d of this application.

Summary of the Invention CK, In a first broad aspect, the present invention provides a security closure comprising a frame, defining an open portion and a security screen mounted in and closing the open portion, in which the security screen comprises a sheet of non- I expanded perforated aluminium or aluminium alloy.

The perforations are typically arranged in a pattern and are sized to prevent most insect access through the apertures, such as flies, mosquitoes and the like but are sized and spaced to allow substantially unrestricted view through the sheet.

Preferably, the sheet of aluminium has a thickness of from 1.6mm to 2.5mm or more. However,a sheet thickness of about 2.00mm is preferred as it provides a good compromise in terms of cost, unrestricted view, and strength.

The frame of the security closure is also preferably made from aluminium.

Making the frame from the same material as the security screen provides a significant advantage in terms of corrosion. Security closures are typically exposed to the elements, particularly water. Where the closures are made two different metals such as aluminium and steel or stainless steel, for example, electrolytic corrosion occurs where the two different metals are in contact with each other. Isolating the metals, to prevent such corrosion, increases costs. If the frame and screen are made of the same metal, electrolytic corrosion can be avoided.

Typically, the frame has an outer edge which, in use, defines the outer perimeter of the frame and has an inner edge which, in use, surrounds the open portion of the frame. The inner edge may define an open channel formed from two parallel spaced apart walls, the channel having a width approximately the same width as the thickness of the aluminium sheet, for mounting the sheet to the frame.

The open channel is preferably at least 12mm and most preferably around deep.

The screen may be secured in place by rivets passing through apertures in the walls of the channels and the periphery of the screen. The holes will typically be formed by drilling through the walls and screen.

The rivets are most preferably made of aluminium, aluminium alloy or monel.

It is preferred that a closed channel is defined to one side of the open channel for receiving the "blind" end of the rivet.

4 A cover plate is preferably provided for mounting to the other wall of the Schannel for covering the head of the rivet to provide a neat finish. The cover preferably

C

snap fits to the wall of the open channel.

Brief Description of the Drawings A specific embodiment will now be described by way of example only and with (i reference to the accompanying drawings in which: Figure 1 shows an isometric, part sectioned, view of part of a first embodiment of a security door embodying the present invention; Figure 2 shows a further isometric view illustrating a corner of the door with some parts shown cut away; Figure 3 shows a cross section through an open and closed channel of the frame of the door of Figures 1 and 2 illustrating the fixing of the sheet to the frame using rivets; Figure 4 shows a cross-sectional view of a variant of the door frame shown in Figures 1 to 3; Figure 5 shows an isometric view of the door frame of Figure 4; and Figure 6 shows a cross-sectional view of a cover plate of the door frame of Figure 4.

Detailed Description of Preferred Embodiments.

Referring to the drawings, Figure 2 shows a section through a security closure in the form of a security door 10 comprising a rectangular frame 12 and a sheet of perforated (non-expanded) aluminium 14 mounted in the frame. The frame 14 is formed from lengths of aluminium extrusion 16 having the same cross-section. Four lengths of such aluminium section are typically assembled together to form a rectangular frame with mitre joints at its corners, the frame defining a perimeter and inner edge 18 surrounding an open portion which is filled or closed by the perforated aluminium sheet 14, as shown.

The extrusion/section 16 which forms the frame, comprises a first generally rectangular, relatively large, closed channel 20 (which may define external ribs 22 for increased strength and/or decoration) and which in use defines the outer perimeter of the closure.

As is best seen in Figure 3, there is an open channel 24 formed from two spaced apart parallel flanges/walls 26, 28 which extend away from the closed channel 20. The flanges are spaced apart by a distance of approximately 2mm. One flange 26 also defines one wall of a second closed channel 30 having a generally trapezoidal cross a section. With reference again to Figure 3, the other flange 28 defines a means for engaging a cover plate. The means comprise a channel 29 defined between a first rib 30 which projects from the flange adjacent its base and a second rib 32 which projects from the first closed channel 20 parallel to and spaced apart from the flange 28. A rib Cc 34 also projects from the top of the flange and a generally V shaped recess 36 is defined between the rib 34 and the top of the flange.

As shown in Figure 3, a cover plate 50 comprises a plate defining an offset rib S52 at one end for engagement in channel and a hook or rib portion 54 at its other end for engaging in the V shaped recess 36.

C In use, with reference to Figure 2 in particular, four lengths of extrusion are cut with their ends mitred to form a frame 12 sized to fit the required opening and an appropriately sized sheet 14 of perforated aluminium is cut to size to fit within the open portion with the periphery of the sheet located in the open channel 24. A series of holes are then drilled through the flanges and the aluminium sheet 14 and blind rivets 56 inserted to secure the sheet in the channel. Typically, around 40 to 44 rivets may be used. Clearly sufficient rivets must be used to prevent the sheet from being pushed out from the door frame 12. Once the rivets have been inserted, the cover plate 50 is then snap-fitted over the flange 28 to provide a neat finish to the door frame.

In the specific embodiment described and shown, the aluminium sheet has a hole size of 2.41mm and a pitch of 3.6mm with the holes being staggered. The particular size and pitch could be varied. The aluminium is 2mm thick although, a door formed from a sheet of aluminium having a 1.6mm thickness will pass the necessary tests. The open area of the sheet is around 40% of the total sheet area, which is sufficient to give an essentially unrestricted view through the door.

Figures 4, 5 and 6 show a variant of the extrusions used to form the frame of Figures 1 to 3. In this variant, the extrusion 116 is similar to the extrusion 16 of Figures 1 to 3, however the cover 150 and means of mounting the cover 150 to the extrusion 116 is slightly different to obtain a door frame which is largely symmetrical in appearance. In all other respects the extrusion 116 functions and is used in the same way as extrusion 16 of Figures 1 to 3.

With reference to Figure 4, the flange/wall 128 defines a protruding rib 160 at the top of the flange 128 which defines an enlarged rounded end 162. A further, fin shaped, rib 163 projects from the top of the large closed channel 120 adjacent the base of the flange/wall 128.

6 The cover plate 150 includes a base 164 which defines a depending fin shaped d rib 166 which depends from its lower edge, a side wall 168 which extends at right

C

angles to the base and an angled top wall 170 which extends at an angle of about 1350 to the side wall, and whose end defines a rib 172 having a c-shaped cross-section.

As with the embodiment of Figures 1 to 3, in use, four lengths of extrusion 116 Cc and cover plate 150, are cut and their ends mitred. The four length of extrusion 116 are I mitred to form a frame 12 sized to fit the required opening and a suitably sized sheet 14 of perforated aluminium is cut to size to fit within the open portion with the peripheral Sedges of the sheet located in the open channel 124. A series of holes are then drilled through the flanges/walls 126, 128 and the aluminium sheet. blind rivets are inserted N, through the holes to secure the sheet in the channel. Once the rivets have been inserted, the cover plate 150 is then snap-fitted over the flange 28 to provide a neat finish to the door frame. This is done by engaging the c-shaped rib 172 over the rounded rib 162 and snap fitting the fin shaped rib 166 of the cover plate over and behind the rib 163 defined on the top of the closed channel.

As is best seen in Figure 5 when the cover plate is located in position it covers any rivet holes and also approximates to the appearance of the closed channel 120 so that the frame looks neat and looks the same from both front and rear faces.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (3)

1. 2. A security closure as claimed in claim I wherein the sheet of aluminium has a thickness of from 1.6mm to 2.5mm and preferably about 2.00mm.
2. 3. A security closure as claimed in claim 1 or claim 2 wherein the frame of the security closure is also made from aluminium.
3. 4. A security closure as claimed in any one of claims 1 to 3 wherein the frame has San outer edge which, in use, defines an outer perimeter of the frame and has an inner 10 edge which, in use, surrounds the open portion of the frame and defines an open channel formed from two parallel spaced apart walls, for receiving the edges of the sheet for mounting the sheet to the frame. A security closure as claimed in claim 4 wherein a closed channel is defined to one side of the open channel of the frames and wherein the screen is secured in the frame by rivets passing through apertures in the walls of the channels and the periphery of the screen, with the closed channel receiving the "blind" ends of the rivets and wherein a cover plate is preferably provided for mounting to the other wall of the channel for covering the head of the rivet.