GB2268213A - Door structure - Google Patents

Abstract

A door is formed by co-extensive skins (10, 12) of metal sheet which are arranged substantially parallel to each other. Each skin (10, 12) is formed as an open ended tray having two opposing edge margins (16, 18) deflected substantially at right angles to provide lips at those opposing edges. The lip (16) of the skin (10) is itself further folded over inwardly of the tray through substantially 180 DEG . The lips (16, 18) are in each case directed towards the respective other skin (12, 10) so that once the trays are fitted together the overlapping lips (16, 18) provide a reinforced edge face to the door, comprising three layers of metal sheet. This may make the door more resistant to impact damage and forced entry. A material such as a honeycomb lattice of cardboard or wood (14) may be arranged in the space between skins (10, 12). In other examples doors comprise three co-extensive metal skins arranged substantially parallel with spaces between them. <IMAGE>

Description

A DOOR This invention concerns a door comprising co-extensive metal skins arranged substantially parallel.

Solid metal security doors are known. They are extremely heavy and expensive. Also known are security doors comprising substantially parallel metal skins with other material, such as wood or a honeycomb lattice of cardboard sandwiched therebetween. These are lighter and less expensive and generally serve the purpose. To provide a bullet proof door a slab of polycarbonate or the like may be provided as an insert in the cavity between the metal skins in place of or in addition to wood or honeycomb lattice. To provide a sound insulating door plasterboard or the like may alternatively be used as insert material.

Generally, one of the skins of such a door is formed with a rim around its periphery to provide a metal covering to the edge faces of the door and an internal edge flange of the rim is secured to the other skin around the edge margin of one of the major surfaces of the door, e.g. by welding or by interengagement of folded over portions. In this way only a single thickness of sheet metal covers the edge faces of the door, and one major surface carries the joint or seam around its periphery, which may make it a target for break in or may just be unsightly.

An object of the present invention is to provide a door of the above-described general type which is more secure against break in, i.e. which should be less readily penetrated or prised open by customary break in tools.

Another object of the invention is to provide a door of the aforesaid type which can present a plain interior surface, without any seams or joints being apparent and without any door applied ironmongery such as locking mechanisms e.g.

bolts being visible.

Yet another object is to provide a means of enhancing the security or other desirable property, such as sound attenuating property, of an existing metal skinned door.

According to a broad aspect, the invention provides a door comprising co-extensive metal skins arranged substantially parallel, each skin having at least one edge margin deflected so as to provide a substantially perpendicular lip which extends towards the other skin, with the lips of the respective skins overlapping one another to provide at least one edge face to the door, and with at least one of these lips itself being folded over through approximately 1800 so that at least three layers of metal are provided at the said edge face.

In this way, the joint between the respective metal skins is formed at the edge by the overlapping lips, which may conveniently be secured by plug welding. This joint is less accessible to break in than that previously used at the periphery of one of the major surfaces. Moreover, the edge is significantly reinforced by having three layers of metal present. Such a reinforced edge is of particular advantage at the free edge of a door where it is most vulnerable to impact or attempted break in.

Preferably, each skin has a substantially perpendicular lip extending towards the other skin provided along at least two edge margins, the lips of at least one skin being folded over through approximately 1800 at each of those edges of the door so that at least three layers of metal are provided along at least two edge faces of the periphery of the door.

Typically the lips are provided along the free edge of a door and at least the other upright edge. However, provision of a substantially perpendicular lip extending towards the other skin along each edge margin of each skin is also possible, the lips of at least one skin being folded over through approximately 1800 at each edge of the door. In this way at least three layers of metal would be provided along the edge faces of substantially the entire periphery of the door.

Advantageously, in the aforesaid cases the lips of one of the skins fits snugly inside the lips of the other skin. In effect, in the case where each edge margin of each skin is deflected the skins are then like respective trays, each with a rim around its entire periphery or substantially so (there may be gaps at the corners, for instance), the trays nesting one inside the other with their respective rims extending towards each other so as to provide a hollow enclosure bounded around the edges by the overlapping rims.

As in the prior art, an insert of a material such as wood, or polycarbonate, or plasterboard, or a honeycomb lattice of cardboard may substantially or partially fill the space between the respective skins which is bounded along at least one edge, and preferably around two opposing edges, and possibly around the entire periphery, by the overlapping lips.

In certain embodiments, particularly at the free edge and/or top and/or bottom edges of a door in accordance with the invention, the edge margin of one of the skins may be deflected so as to provide, in addition to a substantially perpendicular lip, a flange which extends laterally beyond the lip, substantially parallel to or co-planar with the major surface of the skin. Such a flange provides an abutment surface for contacting and overlying a door jamb element and thus provides further security against break in.

In a development of the invention, which is advantageous in certain circumstances, the door comprises three coextensive, substantially parallel metal skins, the third skin also having at least one edge margin deflected to provide a lip, which lip fits between the overlapping lips of the other two skins.

Provision of a third metal skin obviously enhances the strength of the door and reduces its vulnerability to break in. Furthermore, the edge face or faces of the door where the lip of the third skin fits between the other lips now comprises at least four layers of metal.

Generally, where a third metal skin is provided it is disposed outwardly of the second skin, at a spacing therefrom.

The third metal skin will typically provide the interior surface for the door. This is conveniently achieved by having the lip of the third skin wider in extent than the perpendicular lips of the first and second skins so that even where it projects as far as is possible between the overlapping lips of the first and second skins it still holds the third skin apart from the second skin. The additional space provided between the second and third skins may advantageously accommodate a further insert of a material which is either the same as or different from insert material between the first and second skins. In this way where the same material is used in both spaces properties attributed to a particular insert material may be enhanced, or where different materials are used in the respective spaces the properties of different insert materials may be combined.

For example where a security door with bullet proof properties is required, a timber insert may be used in one space and a polycarbonate insert in the other, or where a door for a refrigerated enclosure is required a polyurethane insert may be used in one space and a rockwool insert in the other.

Equally important in the case of a security door is the possibility of significantly increasing the overall thickness of the door, e.g. doubling it from about 5cm to about 10cm, which will make it more difficult and more time consuming for a thief to penetrate using a tool such as a disc grinder.

Another advantageous possibility afforded by the provision of a third skin spaced away from the first or second skin is that locking mechanisms such as bolts and bolt housings, a considerable number of which may be distributed around the interior of a security door, may be accommodated within the additional space between the second and third skins. They are then no longer visible at the surface of the door facing the interior of the relevant building, i.e. they are concealed by the third skin. In some circumstances this is desirable for aesthetic reasons and for hygiene.

In specific embodiments, the lip of the third skin may advantageously have a stepped or joggled or Z-configuration in profile so as to provide a shoulder for fitting to the edge of the second skin and/or for abutment of a door jamb element.

Specific practical embodiments of the door of the invention will now be described with reference to the accompanying drawings, it being understood that the following detailed description is merely illustrative and not limitative of the scope of the invention. In the drawings: Fig. 1 is a perspective exploded view of a small region at one edge of a first embodiment of a door in accordance with the invention; Fig. 2 is a perspective view of the parts shown in Fig. 1 when fitted together; Fig.3 is a transverse cross-section through the metal skins of the door edge region of Figs. 1 and 2, to an enlarged scale; Figs. 4, 5 and 6a are views corresponding to Figs. 1 to 3 of a second embodiment of a door in accordance with the invention; Fig. 6b shows an alternative to Fig. 6a; and Figs. 7, 8 and 9 are views corresponding to Figs. 1 to 3 of a third embodiment of a door in accordance with the invention.

With reference to Figs. 1 to 3, the first embodiment consists of a door of conventional rectangular shape formed by co-extensive skins 10, 12 of metal sheet which are arranged substantially parallel to each other. In this example a honeycomb lattice 14 of cardboard is arranged in the space between the skins 10, 12. In other examples other material may, of course, be used as an insert between the skins 10, 12.

Each skin 10, 12 is formed as an open ended tray having two opposing edge margins deflected substantially at right angles to provide lips at those opposing edges. Since Fig. 1 concerns the region at only one edge of the door, only one such lip 16, 18 for each skin 10, 12 is illustrated here. The lip 16 of the skin 10 is itself further folded over inwardly of the tray through substantially 1800. The tray formed by the skin 10 is slightly larger than that formed by the skin 12 so that the door is assembled, as shown in Fig. 1, with the lip 18 fitting snugly inside the lip 16. The lips 16, 18 are in each case directed towards the respective other skin 12, 10 so that once the trays are fitted together the overlapping lips 16, 18 provide a reinforced edge face to the door, comprising three layers of metal sheet.An opposing edge face of the door is also reinforced by the other pair of overlapping lips (not illustrated).

The usual metal used for the skins 10, 12 is mild steel, but other metals are possible e.g. stainless steel or brass.

The skins 10, 12 are conveniently secured, once assembled, by plug welding, with appropriate apertures 20 to allow for this provided at intervals in the two layers of the outermost lip 16. However, securement by other means, even just by friction fit of the lip 18 within the lip 16 is possible.

As well as providing general reinforcement so that the edge of the door is more resistant to impact damage and forced entry, the three metal layers around the edge allow for the asuntersinking of a lock plate, by cutting an aperture in one or two outermost layers, while still retaining at least one layer overlying the interior space or insert material.

With reference to Figs. 4 to 6a, the second embodiment also consists of a door of conventional rectangular shape formed by co-extensive skins 30, 32 of metal sheet arranged substantially parallel to each other. In this particular example an insert of wood 34 is arranged in the space between the skins 30, 32. In other examples, other insert materials may be used.

Again, each skin 30, 32 is formed as an open ended tray, having two opposing edge margins deflected to provide two substantially perpendicular opposing lips on each skin. One lip 36, 38 on each skin 30, 32 is illustrated. The edge margin of the skin 32 is, in this respect, simply deflected at right angles to provide a single layer lip 38. In contrast the edge margin of the skin 30 is folded over, as well as being deflected. As shown in the drawings, it provides a flange 40, which is co-planar with the skin and is of double thickness by virtue of the sheet material being folded back on itself through about 1800, as well as the perpendicular lip 36, which is also of double thickness by virtue of the sheet material being folded over through 1800. The flange 40 extends laterally beyond the lip 36, as shown.The flange 40 may be formed just at the free edge of the door or at the free edge and top and bottom edges to provide an abutment to a door jamb element for purposes of added security.

The materials and manner of securement of the skins are as specified in the first embodiment, with apertures 42 shown in the illustrated example for purposes of plug welding.

Various modifications may be made to the embodiment illustrated in Figs. 4 to 6a. An example modification is shown in Fig. 6b. This concerns a metal element 41 which .comprises two limbs 41a and 41b extending at right angles to one another and with one limb 41b folded over through approximately 1800. The element 41 may be welded to a folded edge of a metal skin so that limb 41a provides a flange, for example. Use of the element is advantageous in that, when welded to a deflected or folded edge margin, it provides additional layers of metal to resist break-in.

In particular, in the case where a skin 30 is deflected and folded to provide a double thickness flange 40, the element 41 may be employed so that limb 41a is alongside flange 40 to provide three thicknesses of material instead of two. This is advantageous since a flange 40 is particularly prone to attack in an attempt to gain access to locking mechanisms.

Turning now to Figs. 7 to 9, the third embodiment also consists of a door of conventional rectangular shape, but in this case it is formed of three co-extensive metal skins 50, 52, 54, with a wooden insert 56 arranged between the first and second skins 50, 52 and a honeycomb lattice of cardboard 57 between the second and third skins 52, 54. The first and second skins 50, 52 are identically formed to the skins of the second embodiment with respective interfitting perpendicular lips 58, 60 and a flange 62 coplanar with the first skin 50.

The third skin 54 is also provided with opposing lips at two of its edges. One such lip 64 is shown in the figure. In this example the lip 64 is of stepped or joggled or Zconfiguration having a proximal section 66 deflected perpendicularly from the major extent of the skin 54, a central section 68 which is deflected outwardly so as to lie substantially parallel to the major extent of the skin 54, and a distal section 70 which is deflected again through a right angle away from the proximal section, but substantially parallel thereto. As clearly illustrated, the third skin 54 is mounted outside the second skin 52, i.e. at the side remote from the first skin 50, with the central section 68 of the lip 64 abutting the edge margin of the skin 52 and the distal section thereof inserted between the interfitted lips 58, 60 of the first and second skins 50, 52.Thus, the edge face of the door bounded by the lip 58 consists of four layers of sheet metal.

Apertures 72, 74 are shown in the lips 58, 64 of the first and third skins 50, 54 for purposes of plug welding, although other means of securement are possible.

The advantages of providing for a third skin 54 to be fitted to the door have been discussed earlier in the text.

It will be appreciated that the embodiment illustrated in Figs. 7 to 9 is exemplary. In other embodiments the lip of the third skin need not be stepped or Z-configuration and may be a single perpendicular lip, preferably of greater extent than the rims of the first and second skins so that when inserted therebetween to fullest extent, the third skin 54 is still supported at a spacing from the second skin 52.

In other embodiments falling within the broad aspect of the invention, this lip 58 of the first skin 50 need not be folded over or of double thickness, and of course, the flange 62 is optional.

Also, as discussed earlier, whilst the accompanying figures show provision of a lip at an edge margin of each skin to provide the free edge face of a door, clearly additional lips may be formed at other edge margins of the skins to provide edge facing for the top and/or bottom of a door, as desired.

Many other variations are possible within the scope of the invention.

Claims (16)

1. A door comprising co-extensive metal skins arranged substantially parallel, each skin having at least one edge margin deflected so as to provide a substantially perpendicular lip which extends towards the other skin, with the lips of the respective skins overlapping one another to provide at least one edge face to the door, and with at least one of these lips itself being folded over so that at least three layers of metal are provided at the said edge face.

2. A door according to Claim 1 wherein each skin has a substantially perpendicular lip extending towards the other skin provided along at least two edge margins, the lips of at least one skin being folded over at each of those edges of the door so that at least three layers of metal are provided along at least two edge faces of the periphery of the door.

3. A door according to Claim 2 having lips provided alon#g the free edge and at least the other upright edge.

4. A door according to Claim 2 or 3 having a substantially perpendicular lip extending towards the other skin along each edge margin of each skin.

5. A door according to Claim 4 wherein the lips of at least one skin are folded over at each edge of the door.

6. A door according to any preceding claim wherein a lip of one of the skins is fitted closely inside a lip of the other skin.

7. A door according to any preceding claim wherein an edge margin of one of the skins is deflected so as to provide a flange which extends laterally beyond the substantially perpendicular lip, and arranged substantially parallel to or co-planar with the major surface of the skin.

8. A door according to Claim 7 having flanges extending from at least the free edge and top edge of the door.

9. A door according to any preceding claim having an insert of a material in the space between the respective skins.

10. A door according to any preceding claim having three co extensive substantially parallel metal skins.

11. A door according to Claim 10 wherein the third skin also has at least one edge margin deflected to provide a lip, which lip fits between the overlapping lips of the other two skins.

12. A door according to Claim 10 or 11 having a third metal skin disposed outwardly of the second skin, at a spacing therefrom.

13. A door according to Claim 11 or 12 wherein the lip of the third skin is wider in extent than perpendicular lips of the first#or second skins.

14. A door according to any one of claims 10 to 13 wherein the third skin accommodates an insert of a material.

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15. A door according to any one of claims 10 to 14 having a locking mechanism accommodated within the space between the second and third skins.

16. A door substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.