GB2293400A - Armoured door - Google Patents

Abstract

An armoured door comprising a layer of glass fibre reinforced armour (3) between and spaced from each of a pair of layers of medium density fibreboard (1) and (5) by foam material (2) and (4). In alternative embodiments the layer (3) can be of steel or aluminium and the layers (1) and (5) can be of plywood, hardboard or glassfibre reinforced plastic. <IMAGE>

Description

ARMOURED DOOR This invention relates to armoured doors.

Known armoured doors are sandwiches of timber and glass fibre - reinforced armour which comprises a compressed stack of layers of woven glass cloth impregnated with a synthetic resin which has been cured. Timber is used because door manufacturers are joiners and they like to use it. However, the timber used is heavy duty plywood which is heavy and causes armoured doors of sandwich construction which incorporate it to be heavy. Another problem is that the glass fibre reinforced armour is difficult to machine and is expensive compared to the timber. In the more common form of armoured door having a sandwich construction, the armour is the filling of the sandwich. In another known form, the timber is the filling which has the advantage of being lower in cost because it includes less armour, but its weight and machinability are still problems.Steel has been used as the armour instead of the glass-fibre reinforced armour material but that also presents a weight problem because the steel is heavy.

Most commercially available doors which are not armoured are hollow. Such doors formed of timber are commonplace.

Similar doors formed by moulding UPVC are readily available but they are not strong.

An object of this invention is to avoid the above mentioned problems of known armoured doors.

According to this invention there is provided an armoured door comprising a layer of armour material between and spaced from each of a pair of layers of ballistic energy absorbing material by a lightweight infilling material.

Preferably the infilling material is mouldable.

The infilling material may be foamed plastics material and the ballistic energy absorbing material may be medium density fibreboard or glass fibre reinforced plastic or hardboard or plywood.

The armour material may be metallic such as steel or aluminium, or may be non-metallic. The preferred form of armour material is glass-fibre reinforced armour which comprises a compressed stack of layers of woven glass cloth impregnated with a synthetic resin which has been cured.

In a preferred embodiment, a sandwich construction comprising the layer of armour material between layers of foam plastics material and the layers of ballistic energy absorbing material is a one-piece moulding. The one-piece moulding may be provided with a timber edging around its periphery. In addition, or in the alternative, the moulding may be provided with a nonstructural veneer or laminate on the outer faces of the two layers of ballistic energy absorbing material for aesthetic purposes.

Any suitable foam plastics material such as a phenolic, may be used. It may be a closed or an open foam and it would be lighter than timber.

The advantage of the preferred embodiment of this invention is that there is provided an armoured door which is approximately 50% lighter than known armoured doors and can be formed as a one piece moulding, thereby considerably simplifying the construction process.

A further advantage is that the use of foam rather than timber or air reduces the risk of damage should there be a fire,as the foam is fire retardant. Also, the door of the present invention provides a more stable structure than that provided by the doors currently available.

An embodiment of the present invention is described now by way of example with reference to the accompanying drawings of which: Figure 1 shows a door; Figure 2 shows a section through the line II.II in Figure 1.

Figure 2 shows the door comprises a stack of layers arranged so that a first layer of medium density fibreboard 1 is adjacent to a first layer of foam 2 which in turn is adjacent to a layer of glass fibre reinforced armour 3 which is adjacent to a second layer of foam 4 which is also adjacent a second layer of medium density fibreboard 5. The edges 6 defined by the stack are lipped by hardboard 7.

The armoured door which comprises the first layer of foam 2, the layer of glass fibre reinforced armour 3 and the second layer of foam 4 sandwiched between the layers of medium density fibreboard 1,5 is formed as a one-piece moulding. The timber edging 7 is fitted subsequently and a veneer added to the outer surfaces.

Claims (13)

1. An armoured door comprising a layer of armour material between and spaced from each of a pair of layers of ballistic energy absorbing material by a lightweight infilling material.

2. An armoured door according to claim 1 wherein the infilling material is mouldable.

3. An armoured door according to claim 1 or claim 2 wherein the infilling material is foamed plastics material.

4. An armoured door according to claim 3, wherein the foamed plastics material is a phenolic foam.

5. An armoured door according to claim 3 or claim 4, wherein the foam plastics material may be open or closed.

6. An armoured door according to any one of claims 1 to 5 wherein the ballistic energy absorbing material is medium density fibreboard.

7. An armoured door according to any one of claims 1 to 5 wherein the ballistic energy absorbing material is glass fibre reinforced plastic or hardboard or plywood.

8. An armoured door according to any of the preceding claims wherein the armour material is metallic.

9. An armoured door according to claim 8 wherein the armour material is steel or aluminium.

10. An armoured door according to any of claims 1 to 7 wherein the armour material is non-metallic.

11. An armoured door according to claim 10 wherein the armour material is glass fibre reinforced armour which comprises a compressed stack of layers of woven glass cloth impregnated with a synthetic resin which has been cured.

12. An armoured door according to any of the preceding claims wherein the door is formed as a one-piece moulding.

13. An armoured door substantially as described hereinbefore with reference to the accompanying drawings and as shown in Figure 2 of those drawings.