AU686972B1 - A security grille - Google Patents

Description

Name of Applicant: Actual Inventor: Address for Service: Title of Invention:

AUSTRALIA

Patents act 1990 Complete Specification For a Petty Patent Jeffrey David Goucher Jeffrey David Goucher J D Goucher 18 Dundee St.

Hlolland Park, Qld 4121 Australia.

A Security Grille e e.

0* The following statement is a full description of this invention, including the best method of performing it knowni to me 5**t

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A Security Grille This invention relates to a mainly aluminium security grille which is not easily cut with a hacksaw or similar implement.

There are many types of security grilles and bars used to prevent intruders from gaining access via windows and doors in buildings. These security grilles for brevity the term security grilles will be used to include all types of bars, meshes, screens and the like whether fitted to doors, windows or other apertures are usually constructed either of steel, aluminium or other metals.

Aluminium is widely used in domestic security grilles. It is highly resistant to corrosion, compatible with aluminium window frames, easily formed into sections and inexpensive. Due to it's low tensile strength and ease of cutting aluminium is rarely used in bars and other slender sections. Instead it is typically formed into mesh type grilles with many short interconnecting members. These mesh type security grilles have the disadvantage of being quite unsightly and they substantially reduce the passage of light and breeze through an opening.

Steel has greater tensile strength and resistance to cutting than aluminium and may be used in slender sections to form security bars. However the application of steel for security grilles is greatly limited by it's propensity for rusting. Steel is mainly used for internal security grilles and for commercial applications where it's security advantages outweigh the maintenance problems.

These problems are overcome by the present invention, which provides a securi grille which comprises aluminium bars each having a hollow whic s longitudinally through the bar. A round rod made from a suitably aterial as to resist cutting with a hacksaw or similar impleient aving a diameter smaller than that of the hole in the bar is inse o each bar such that the rod is free to rotate within the bar.

These r ay suitab be made from high tensile steel, spring steel or any other suitable material.

These problems are overcome by the present invention, which provides a security grille comprising an aluminium perimeter frame and a plurality of aluminium bars fixed by welding or other suitable means into said perimeter frame to form a rigid security grille.

Each bar has a hollow which runs longitudinally through the bar into which is inserted a round rod made of a suitably hard material as to resist cutting with a hacksaw or similar implement.

The rod may suitably be made from high tensile steel, spring steel or any other suitable materials, The rod has a diameter smaller than the diameter of the hollow in the aluminium bar and is free to rotate within the bar.

These bars are very difficult to cut with a hacksaw or similar implement. The saw will cut through the outer aluminium casing and then strike the very hard inner rod which is not readily sawn in such a manner. The sawing process is further impeded by the fact that since the rod is free to rotate about it's longitudinal axis it will rotate when the saw blade strikes the surface of the rod tangentially, thus preventing the saw from effectively engaging the rod.

While it is preferred that the bars be welded to the aluminium perimeter frame, alternatively rivets, screws or other fasteners may be used.

o 0 6 *6 *e• I- 2 Once assembled these bars are very difficult to cut with a hacksaw or similar implement. The saw will cut through the outer aluminium casing and then strik e very hard inner rod which is not readily sawn in such a manner. The s ing process is further impeded by the fact that since the rod is free to rotate ut it's longitudinal axis it will rotate when the saw blade strikes the suf e of the rod tangentially, thus preventing the saw from effectively enga in ie rod.

A plurality of such bars xed to a suitable frame to form a security grille. While it is preferred tha e bars be welded to an aluminium frame, alternatively rivets, screws or ot asteners may be used and the frame may be made from any material suitable -or the purpose.

The resulting security grille is very strong, will not corrode in external applications, can be installed directly into aluminium windows and is not easily cut.

0 In order that the invention may be more fully understood a preferred embodiment will now be described with reference to the following drawings, in which: 0 FIG. 1 shows a perspective view of one example of a security grille according to this invention.

FIG. 2 is a sectional view along A- A of FIG. 1.

oee o bke. e o-rs o-C Lhe secaLLr.c FIG. 3. is a sectional view offcuri bar orn i ntin oe IG. As shown in FIG. 1. the security grille according to this invention comprises a perimeter frame 1 into which is fixed a plurality of bars 2 which are arranged in such a manner as to provide an effective security barrier. Each bar 2 is welded to the perimeter frame 1 at both ends 3. The bars 2 are also welded to each other at every point of intersection 4. An insect screen 5 is attached to the inside face of the perimeter frame 1 As can be seen in Fig. 2. The perimeter frame 1 may be made from a suitable R4 A ,aluminium extrusion 6 which is additionally designed to incorporate a groove 7 for I r RIPIP receiving a flexible spline 8 which retains the edge of the insect screen 5. When the security grille is mounted in a window, the insect screen 5 faces inward such that the bars 2 are to the outside of the insect screen On one edge, the extrusion 6 incorporates a flat step 9A and another flat step 9B, which is parallel to the flat step 9A and separated by a perpendicular face 10, The perpendicular distance from the flat step 9A to the flat step 9B is equal to the thickness of the bars 2 such that the inner face 11 of a bar 2 resting against the flat step 9B is flush with the flat step 9A. The flat steps 9A and 9B provide. aitable points of attachment for the ends 3 of the bars 2.

The perimeter frame 1 is formed by cutting sections of the extrusion 6 to the required length and mitring the comers such that, when assembled, they form a substantially rectangular frame 1 with the stepped sections 9A and 9B all facing inwardly. The sides i. of the perimeter frame 1 may be joined together either by means of suitable comer 9. *stakes (not shown or by welding the comers. The perimeter frame 1 is designed to fit into a window frame and may be fixed by any suitable means to the window frame or to the adjacent surrounds or in the case of a door, to the door jams.

*9 The construction of the bars 2 is shown in FIG. 2. and FIG. 3. Each bar 2 comprises a °hollow bar section 12 made of aluminium. The bar section 12 incorporates a hollow 13 which runs iongitudinally through the bar section 12, The hollow 13 may be of any suitable sectional shape. Such bar sections 12 may suitably be formed by extrusion. A round rod 14 which is made of a suitably hard material as to resist cutting with a hacksaw or similar implement and which has a diameter smaller than that of the hollow 13, is fully inserted into the hollow 13. The rod 14 may suitably be made of high tensile spring steel or hardened steel.

Typically the difference in diameter between the rod 14 and the hollow 13 is greater than 0.2mm. The rod 14 must be free to rotate about it's longitudinal axis. To prevent the ends of the rod 14 from binding or becoming otherwise restricted when the bar section 12 is attached to the perimeter frame 1, the rod 14 is cut suitably shorter than the bar section 12 and a ball bearing 15 FIG. 2. or similar spacer is inserted into the IIP-- lll -P IUP IPW 4 hollow 13 at each end of the bar section 12. The ends of the bar section 12 are then sealed to prevent the ingress of water into the hollow 13.

Bars 2 of the correct length are arranged within the perimeter frame 1 in such a manner as to form an effective security grille. Typically the bars 2 are arranged into a grid pattern of horizontal and vertical bars, usually with bar spacings of between 100mm and 300mirz (FIG. 1. All bars 2 which have the same orientation eg. the horizontal bars are attached to the same flat step on the perimeter frame 1 eg. flat step 9A while all bars which are of the opposite orientation eg. the vertical bars are attached to the other flat step on the perimeter frame 1 eg. flat step 9B In this way the bars 2 of differing orientations intersect in different planes and just make contact at the point of intersection 4. The bars 2 are suitably attached to the perimeter frame 1 by welding the bar section 12 to the frame section 6 and the bars 2 are also welded or otherwise attached to each other at each point of intersection 4.

V The security grille as described above has a number of advantages. Firstly it provides a security grille which is very strong and not easily cut. The bars 2 in this security grille are very difficult to cut because a hacksaw or any similar implement will cut through the aluminium bar section 12 and then strike the very hard inner red 14 which is not o readily sawn in such a manner. The sawing process is further impeded by the fact that since the rod 14 is free to rotate about its longitudinal axis, when the saw blade strikes the rod 14 tangentially it causes the rod 14 to roll such that there is little or no relative movement between the saw blade and the surface of the rod 14, thus preventing the saw from cutting the rod 14.

Secondly it provides a security grille which has all of the advantages of an aluminium grille such as resistance to corrosion, low cost, ease of manufacture, ease of powdercoating or anodising and compatibility with aluminium framed windows, however it provides a much more open and unobtrusive grille than present 'mesh' type aluminium security grilles, without compromising the security value of the grille.

~s-a The foregoing describes only one embodiment of the invention. Bars as described here may be arranged in any manner which prevents unwanted access through a window or door and may be attached by any means to any suitable frame, without departing from the scope of this invention as defined in the following claims.

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Claims (6)

1. A security grille for a window or door opening or the like, comprising an aluminium perimeter frame and a plurality of aluminium bars fixed by welding or other means into said perimeter frame to form a rigid security grille, each bar having a hollow which runs longitudinally through the bar into which is inserted a round rod made of a suitable material as to resist cutting with a hacksaw or similar implement, said rod having a diameter smaller than the diameter of the hollow in the aluminium bar and being free to rotate within the bar.

2. The security grille of claim 1 wherein the aluminium perimeter frame is assembled from an extruded section which provides two adjacent rebates which are separated by a perpendicular distance similar to the thickness of the aluminium bars.

3. The security grille of claims 1 and 2 wherein the aluminium bars are arranged in a squarc or rectangular grid pattern with the ends of the bars of one orientation attached to one rebate on the perimeter frame and the ends of the bars of the opposite orientation attached to the other rebate thus allowing the bars of opposite orientations to intersect in different planes.

4. The security grille of any one of claims 1 to 3 wherein the round rod which is inserted into each aluminium bar is made of high tensile steel.

S The security grille of any one of claims 1 to 3 wherein a ball bearing or similar spacer is inserted into the hollow in each bar at both ends of the round rod prior to the bars being attached to the perimeter frame.

6. A security grille substantially as herein described with reference to the accompanying drawings. Abstract A security grille for a window or door opening or the like, comprising an aluminium perimeter frame and a plurality of bars welded or otherwise fixed to the frame so as to provide a rigid security barrier. The bars are hollow aluminium, bars A round rod (14) made of a suitably hard material as to resist cutting with a hacksaw or similar implement is inserted into the hollow (13) in each bar. The rod (14) is of a smaller diameter than the hollow (13) and is free to rotate within the hollow bar A hacksaw will cut through the aluminium bar section (12) only to strike the very hard rod (14) which is not easily cut in such a manner. The sawing process is further impeded by the tendency of the rod (14) to roll with the movement of the saw blade. 00