NZ524372A - Security closure - Google Patents

Abstract

A security closure comprising a frame (11) which defines the perimeter of the closure where the frame is adapted to be mounted across an opening, a perforate sheet element (13) supported by said frame (11) to close the space defined by the frame (11), said perforate sheet element (13) being formed of a non-expanded sheet material having a plurality of closely spaced apertures punched therein which are dimensioned to prevent insect access through the apertures.

Description

5243 72 "Security Closure" Background This invention relates to security screens which may be applied over windows and/or doorways for the purposes of enabling ventilation through the window or door when 5 open but to prevent the access of insects past the screen. In addition the closure needs to be resistant to destructive forces to prevent unauthorised access past the screen.

Disclosure of the Invention Accordingly, the invention resides in a security closure comprising a frame which 10 defines the perimeter of the closure where the frame is adapted to be mounted across an opening, a metallic perforate sheet element supported by said frame to close the space defined by the frame, said perforate sheet element being formed of a non-expanded stainless steel sheet having a thickness sufficient to withstand penetration of impact by blunt objects and having a plurality of closely spaced 15 apertures punched therein which are dimensioned to prevent insect access through the apertures and wherein the spacing of the apertures provides a substantially unrestricted view through the sheet element.

According to a preferred feature of the invention, the apertures have a diameter of between 1.6 mm to 3.6 mm. According to a preferred feature of the invention, the 20 spacing of the apertures center to center is between 2.0 mm and 3.5 mm. According to a preferred feature of the invention, the thickness of the stainless steel sheeting is between 0.5 mm and 1.0 mm.

According to a preferred feature of the invention the side edges of the sheet element which are supported by the sides of the frame at least are formed with a lip, the frame 25 formed with a recess having an opening directed inwardly with respect to the closure, the edges of the sides of the sheet element having the lip being received within the recess such that the lip is located within the recess, an elongate locking member received and fixed in the recess outward of the lip whereby the locking member is clampingly engaged between the sheet material and the recess.

The invention will be more fully understood in the light of the following description of specific embodiments.

Brief Description of the Drawings The description is made with reference to the accompanying drawings of which: Figure 1 is a schematic partial sectional elevation of a security closure according to the first embodiment illustrating the mounting of the sheet material to the frame; and Figure 2 is a schematic partial sectional elevation of a security closure according to 10 the second embodiment illustrating the mounting of the sheet material to the frame.

Description of Specific Embodiments of the Invention The first embodiment as shown at Figure 1 is directed to a screen closure which may comprise a screen which is applied across a window or alternatively may comprise a screen door where the closure is required to permit air flow through the window or doorway but to prevent the access of insects through the closure and to prevent unauthorised entry through the accessway.

The screen closure according to the embodiment comprises a frame 11 which defines the perimeter of the closure and which is configured to be received in the window or door frame and is adapted to be fixed thereto in the most appropriate 20 manner. The frame 11 is formed of a metal section formed of aluminium where the section is configured to support the edges of a screen 13 which is formed of perforated stainless steel sheet where the perforations are closely spaced and are dimensioned such as to prevent insect access through the apertures. The apertures are formed by punching. The screen material comprises a non-expanded sheet 25 material. The apertures are dimensioned to prevent the passage of insects such as house flies and mosquitoes through them and are spaced sufficiently closely to provide a relatively unrestricted view through the screen when observed from a distance. In addition the grade and thickness of the stainless steel sheeting and the spacing of the apertures is such that the sheet is capable of withstanding significant impact forces created by sharp and blunt objects.

The inner perimeter of the frame 11 is formed with an inwardly directed recess 15 defined between a pair of flanges 17 and 19. The edges of the screen material 13 are each formed with an upstanding lip 21 which is formed by bending the screen material at the edges to form the lip which is substantially perpendicular to the plane of the screen. In mounting the screen to the frame the edge of the screen 13 is 10 received within the recess 15 such that the lip 21 is closely adjacent the base 23 of the recess 15. The screen 13 is retained in position in the recess by means of a elongate locking member 25 which is received between one flange 17 and the opposed face of the screen 13 such that the lip 21 is positioned between locking member 25 and the base 23. The opposed faces of the locking member and the one 15 flange are each formed with a serrated profile where the profiles are complementary and each serration has an inclined face and an upright face and the serrations are arranged on each surface to permit movement of the locking member into the recess but to prevent movement of the locking member from the recess. The locking member 25 is dimensioned such that it will fill the space between the one flange 17 20 and the screen 13 and as a result clampingly retain the screen 13 against the other flange 19. The inner face of the other flange 19 is also formed with a serrated profile of similar if not identical form to that of the one flange 17. In addition the serrated face of the locking member 25 is inclined with respect to the base of the locking member such that in use the side of the locking member having the lower profile is introduced 25 into the recess first whereby with further introduction of the locking member into the recess the locking member becomes wedgingly engaged.

As a result of the first embodiment, a screen closure is provided which is secure in that the means of retaining the screen securely retains the screen in position in the frame without requiring any fixing or bolting of the screen material to the frame. In 30 addition, the use of perforated non-expanded stainless steel sheet material provides a medium which can be more readily powder coated than screen materials which have been used in the past such as mesh or expanded sheet material. In this regard the powder coating which is applied to mesh sheet material and expanded sheet material can be the subject of cracking and resultant separation from the sheet material as a result of localised deflection of the sheet material which results in a 5 spoiling of the appearance of the sheet material and can result in corrosion. In addition it has been found that the perforated sheet material can be harder to cut with a knife or similar sharp instrument when compared to some mesh or expanded sheet materials. The perforated sheet material also provides an aesthetically pleasing appearance.

The second embodiment as shown at Figure 2 is of similar form to the first embodiment and as a result the same reference numerals have been used in relation to corresponding elements of the second embodiment. The second embodiment differs from the first embodiment in that it also includes a layer 27 of an electrical insulator which overlies the lip 21 and extends over at least the adjacent portion of 15 each face of the screen 13 which will be received in the recess 15. The layer 27 is formed of a strip formed of a suitable plastics material and is preformed tot the configuration of profile of the edge of screen. In assembly of the closure the preformed strip 27 is applied over the edge of the screen and the combination of edge and strip is introduced into the recess at which time the locking member is 20 driven into place.

A first example of the second embodiment was constructed to provide a screen door 870mm wide and 2040mm long. The screen was formed of stainless steel sheeting 0.71 mm thick of 304 grade and the frame was formed of an aluminium section as shown at Figure 2. The spacing between the apertures in the stainless steel sheet 25 was 3.1 mm and the diameter of the apertures was 2.06 mm. On testing the door in accordance with the requirements of Appendix A of AS/NZS 2803.1:1994, "Method of Test for Resistance to Forced Entry". The door held all required forces and remained a closed deterrent.

A second example of the second embodiment was constructed to provide a screen door 1250mm wide and 2100mm long. The screen was formed of stainless steel sheeting 0.71 mm thick of 304 grade and the frame was formed of an aluminium section as shown at Figure 2. The spacing between the apertures in the stainless steel sheet was 3.1 mm and the diameter of the apertures was 2.06 mm. On testing the door in accordance with the requirements of Appendix B of AS 2803.2:-1995, 5 "Method of Test for Resistance to Forced Entry". The door held all required forces and remained a closed deterrent.

A third embodiment of the invention is of similar form to the first and second embodiment with the exception that fixing of the locking member to the one flange is supplemented by the use of rivets which are used to fix the one flange to the locking 10 member at spaced intervals along their length.

According to alternative embodiments of the invention the screen is formed of a stainless steel mesh of a suitable grade to provide apertures small enough to prevent insect access through the screen or an expanded stainless steel sheet material which provide apertures small enough to prevent insect access through the screen.

Throughout the specification, unless the context requires otherwise, the word "comprise" or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

It should be appreciated that the scope of the present invention need not be limited to 20 the particular scope of the embodiment described above.

Claims (6)

Claims The claims defining the invention are as follows:

1. A security closure comprising a frame which defines the perimeter of the closure where the frame is adapted to be mounted across an opening, a 5 metallic perforate sheet element supported by said frame to close the space defined by the frame, said perforate sheet element being formed of a non-expanded stainless steel sheet having a thickness sufficient to withstand penetration as a result of impact by blunt objects and having a plurality of closely spaced apertures punched therein which are dimensioned to prevent 10 insect access through the apertures and wherein the spacing of the apertures provides a substantially unrestricted view through the sheet element.

2. A security closure as claimed at claim 1 wherein the apertures have a diameter of between 1.6mm to 3.6mm.

3. A security closure as claimed at claim 1 or claim 2 wherein the invention the 15 spacing of the apertures center to center is between 2.0mm and 3.5mm.

4. A security closure as claimed claim 1 or 2 or 3 wherein the thickness of the sheet element is between 0.5mm and 1.0mm.

5. A security closure as claimed at any one of claims 1 to 4 wherein the side edges of the sheet element which are supported by the sides of the frame at 20 least are formed with a lip, the frame formed with a recess having an opening directed inwardly with respect to the closure, the edges of the sides of the sheet element having the lip being received within the recess such that the lip is located within the recess, an elongate locking member received and fixed in the recess outward of the lip whereby the locking member is clampingly engaged 25 between the sheet material and the recess. -7-

6. A security closure substantially as herein described with reference to the accompanying drawings. END OF CLAIMS -8- ABSTRACT A security closure comprising a frame which defines the perimeter of the closure where the frame is adapted to be mounted across an opening, a perforate sheet element supported by said frame to close the space defined by the frame, said perforate sheet element being formed of a non-expanded sheet material having a plurality of closely spaced apertures punched therein which are dimensioned to prevent insect access through the apertures.