GB2081787A

GB2081787A - Door

Info

Publication number: GB2081787A
Application number: GB8122912A
Authority: GB
Original assignee: SVENSKA DOERR AB
Current assignee: SVENSKA DOERR AB
Priority date: 1980-07-29
Filing date: 1981-07-24
Publication date: 1982-02-24
Also published as: DE3129579A1; FI69907C; FI69907B; FR2487904A1; FI812359L; GB2081787B; SE8005449L; FR2487904B1; DK337581A; NO812586L

Abstract

A door intended to provide good fire protection while at the same time meeting stringent sound reduction requirements. It comprises a framing of timbers (10) whereto facings (12) in the form of skins are fixed so as to enclose a space in which one or a plurality of parallel core sheets (14; 18, 20, 22) are provided. At least two of the sheets (12, 14; 12, 18, 20, 22) are united only partially. The union, preferably bonded, is in the form of one or more continuous or discontinuous strips 16 and/or spots separated by a distance which, with the exception of bonding at or near the edges of the sheet faces, exceeds 40 cm. <IMAGE>

Description

SPECIFICATION Door The present invention is concerned with a door, more particularly a door leaf, comprising a framing, facings in the form of skins fastened thereto, and either one or a plurality of parallel core sheets fixed in the space between the framing and the said facings.

The new door construction is primarily intended for use where doors are required under the applicable regulations to meet certain conditions of both sound reduction and fire protection. Previously difficulty has been experienced in designing a practical, functional door which combines these requirements in a satisfactory manner. It has been found that a door leaf of the type mentioned in the ingress has very good sound reduction properties if the core boards are united loosely to permit a certain degree of relative motion among them. To further enhance the sound reduction it has also been found appropriate to use sheets of alternately higher and lower density as core boads.

In order for the door to perform satisfactorily as fire protection, however, it is necessary that its core, i.e. the core sheets, shall not fall out of the framing even if the facings should come loose or be destroyed by fire. It has been found inadequate and practically complicated to fix the core sheets to the framing by means of rebates etc. This type of fixing easily gives away at the high temperatures in question. An example of a door constructed in this known manner is illustrated in Swedish Patent 330 250. In a door of thickness 40-60 mm this construction gives a sound reduction of 30-40 dB. When one of the facings of a door according to the aforesaid patent has burnt completely the adjacent laminated board falls out, which means that the latter contributes nothing at all from the point of view of fire protection.The rebated central board provides moderate protection until it too falls out. What is left is the other laminated board. A door of this construction must therefore be dimensioned so that in case of fire it will afford protection in case of fire by means of a single laminated board for 20-25 minutes (the facing comes loose after 4-6 minutes, the centre board after another 45 minutes). If all the boards could be utilized the door would provide fire protection for one hour.

Thus the door as disclosed in the patent is grossly over-dimensioned for fire protection.

With some simplification it may be said that the best fire protection is achieved by making the door completely solid, i.e. with the facings united to each other at every point. For the purposes of sound insulation, however, the facings should be completely separated, both along their edges and on face.

Normally a door must have rigid unions along the framing. Fire doors have been constructed with solid cores, while sound insulating doors have cores as flexible as possible, and the combination fire and sound insulating door has been over-dimensioned.

Now it has been found, surprisingly, that when using sheet or board materials as door core materials it is possible to unite the boards or sheets to the facings (and, if desired, to each other) if the said unions are effected in a certain manner, namely by partial bonding.

This partial bonding, preferably in the form of strip sticking or spot sticking with the strips or spots spaced not less than 40-50 cm apart, has the result on the one hand that most of the sound insulating effect of a completely loose core is retained, and on the other hand, even if the boards or sheets are of low intrinsic strength, that they remain in place and contribute positively to the fire resistance of the door.

The strips or spots are preferably located near the perimeter of the core board or boards.

To further enhance the effect the door framing may be split, e.g. as disclosed in Swedish Patent 349 093.

This method makes it possible to construct a door only 40 mm thick whose sound reduction may exceed 35 dB and whose fire resistance is over 30 minutes. The above-mentioned core sheets are preferably united with at least one glued joint. The width of this glued joint along the edges shall be as small as possible, depending among other things on the relative mechanical strength of the sheets. A suitable width may be 1 to 3 cm and it should not exceed 10 cm. To secure the desired sound insulation and fire resistance it is particularly advantageous to use as core sheets two sheets of porous wood fibreboard sandwiching a sheet of thinner, harder wood fibre board. Naturally other sheet materials and combinations thereof may also be considered.

Examples are chipboard, vermiculite boards, sheet metal (e.g. between sheets of other material), etc.

Sheet metal may be of iron, lead etc. With these variations a still wider range of both sound reduction and fire resistance becomes available.

The invention will be described more particularly in the form of two embodiments thereof with reference to the accompanying drawings, wherein identical reference numbers are used to denote identical components in the two figures.

Fig. 1 shows a perspective section through the edge of a door leaf constructed on the principles of the invention.

Fig. 2 shows a similar perspective section of a door leaf modified in certain respects from the door leaf of Fig. 1.

The door leaf illustrated in part in Fig. 1 comprises a rectangular framing consisting of jointed timbers 10 (only one is shown in the figure). Fixed to this framing, which substantially surrounds the perimeter of the door, are two parallel facing sheets 12, so that a clear space is enclosed between the framing and the facings.

The facings are preferably made of hard wood fibre board approximately 3 mm thick bonded direct to the framing. In the above-mentioned space two sheets 14 of porous wood fibreboard are enclosed. The porous boards 14 are united to each other in close proximity to at least two edges. The union is illustrated in Fig. 1 in the form of a continuous glued joint 16 located a short distance inside the framing timbers 10 and extending a few centimetres in between the core boards 14 from each timber. The facings 12 and the core boards 14 may with advantage be bonded to each other by gluing all over, but it is possible in this case too to unite the boards in the vicinity of at least two edges only, i.e. in the area just inside the framing timbers 10.

The above embodiment of the door leaf as illustrated in Fig. 1 shows the invention in one of its very simplest forms. However, a far superior door, especially with regard to sound reduction, can be achieved with the construction illustrated in Fig. 2. Here too the door comprises a framing of jointed timbers 10, facings 12 fixed to the framing, and core boards 18, 20 in the space enclosed between the framing and the facings. In this case the core boards are three in number and they are fixed to the facings 12 via intermediate boards 22. The intermediate boards are bonded both to their respective facings 12 and to their respective core boards 18. The intermediate boards 22 and the central board 20, like the facing sheets 12, are of hard wood fibre board. In the present case there is a glued joint 24 on each side of the central board 20 and also a glued joint 25 between the core boards 18 and the intermediate boards 22. All the glued joints are located a short distance inside the edges of the respective boards. It should be observed that the stability of the facings is essential to the bond between the core and the facing.

The door leaves presented in the examples of embodiment above can naturally be modified within the terms of the invention. Thus, for example, the number of core sheets is not critical.

In certain embodiments, it may be appropriate to use four or five such sheets. Furthermore it is possible to unite the sheets indirectly by means of shims or similar between the edges of adjacent sheets.

Claims

1. A door leaf comprising a framing (10), facings (12) fixed to the framing in the form of skins, and either one or a plurality of parallel core sheets (14; 18, 20) fixed in the space enclosed bythe framing and the facing, characterized in that at least two of the sheets (12, 14: 12, 18, 20, 22)' are united only partially and that the union is in the form of one or more continuous or discontinuous strips and/or spots separated by a distance which, with the exception of bonding, if any, at or near the edges of the boards, exceeds 40 cm.

2. A door leaf as claimed in Claim 1 characterized in that the sheets (12,14; 12,18, 20, 22) are united only at or in close proximity to one or more of the edges of the adjacent faces thereof.

3. A door leaf as claimed in Claim 1 or 2, characterized in that the sheets (14; 18, 20, 22) are bonded together by adhesive.

4. A door leaf as claimed in any of Claims 1 to 3, characterized in that the bonded outer portions of the sheets (14; 1 8, 20, 22) extend inwards over the faces of the core sheets for a distance of approximately 1 to 10 cm from the edges thereof.

5. A door leaf as claimed in any of Claims 1 to 4, characterized in that the core sheets (14) are bonded to the respective facings only.

6. A door leaf as claimed in any of Claims 1 to 4, characterized by intermediate sheets (22) bonded along the edges between the respective core sheets (18) and facings (12).

7. A door leaf as claimed in any of Claims 1 to 6, characterized in that the core sheet(s) (14; 18, 20, 22) consist of wood fibre board, chipboard, vermiculite sheets, sheet metal, etc.

8. A door leaf as claimed in any of Claims 1 to 7, characterized in that the core sheets comprise as least two sheets of porous wood fibre board (18) sandwiching a sheet of thinner, harder wood fibre board (20).