WO1981000585A1

WO1981000585A1 - Wooden girder for building purpose

Info

Publication number: WO1981000585A1
Application number: PCT/SE1980/000217
Authority: WO
Inventors: O Oebrink
Original assignee: Individual
Current assignee: Individual
Priority date: 1979-08-23
Filing date: 1980-08-22
Publication date: 1981-03-05
Anticipated expiration: 1982-02-23
Also published as: DK179381A; SE437391B; SE7907063L; NO811363L

Abstract

Embodiment of a wooden girder, which is so formed that the insulating properties are very good and the depth of the web of the wooden girder is directly adapted to the thickness of a wall, i.e. to the thickness of the isolation. The wooden girder is also suitable for working and nailing can easily be performed. The wooden girder can also meet other demands which can be made on wooden girders for instance admissible load, axial load and refractoriness and the wooden girder comprises two parallel wooden beams (1, 2) joined by spacing element (3). The spacing element consists of polyurethane foam, which binds the two wooden beams (1, 2) together with a distance which is adapted to the wanted depth of web of the wooden girder.

Description

WOODEN GIRDER FOR BUILDING PURPOSE

This invention relates to wooden girder for house buil¬ ding purposes including two parallel wooden beams having a spa¬ cing element them between. The invention also relates to a method for manufacturing such a wooden girder.

In structures where wooden girders are used upright in wall structures, these wooden girders have been of com¬ pact wood having a flange depth which corresponds to the thickness of the wall or to a part of the thickness of the wall. The heat isolation of walls has, however, in¬ creased during the last years and therefore also the thickness of the wall per se, which means that the com¬ mon dimensions of wooden girders can not be used, but the girders must be composed in order to increase the flange depth. It is also known that the wooden girders occupies an area of about 15% of the total wall area and this means that the area of heat transferring bridges are great because wood has a relatively bad heat insulating capaci¬ ty. It has been "proposed to increase the heat insulating capacity of wooden girders and increase the flange depth ' by composing a wooden girder of two wooden beams joined by a web of wood fibre board. It is also known -tς> compose a wooden girder of steel plates and wooden laths and in this case an isolation is placed between the two wooden beams..When manufacturing wooden beams according o these known methods it will mean hand craft, which leads to a relatively expensive product.

The object of the invention is to present a wooden girder, which has _^ good insulating capacities, whereby the flange depth corresponds to the thickness of the wall, that it to say the thickness of the isolation. The wooden girder according to the invention can easily be processed and nails are easily driven in. Other demands on wooden

BUREAU

OMPI girders as admissible load, axial load and fire refractoriness are met by the wooden girder according to the invention.

The invention is characterized in that the spacing ele- ments are of polyurethane foam, which join; two wooden beams with a distance in parallel which corresponds to the wanted flange depth of the wooden girder. The method of manufacturing a wooden girder according the invention is characterized in that a number of wooden beams are placed side by side in a box shaped fixture to form a layer, that a similar number of wooden beams are placed side by side to form a second layer in a cover shaped fixture, which is adapted to said box shaped fixture, that the cover shaped fixture is placed onto the box shaped fixture so that a closed space is formed between the two layers and the confining sides of the two fix¬ tures, in which space polyurethane foam is inserted to join the two layers, whereafter the two in such way joined layers are parted into pieces by cuts , which are parallel to the wooden beams and are at right angle to the layers.

The wooden girder according to the invention will be described in the following with ref rence to accompa¬ nying drawings.

Fig. 1 is a cross-section through a perspective view of a wooden girder according to the invention and Fig. 2 is a cross-section through a fixture arrangement for producing the wooden girder.

Fig. 3 is partly^' a cross-section showing how a number of wooden girders are divided after the manufacturing in the fixture.

0M The wooden girder according to the invention is shown in Fig. 1 and is seen from one end in a perspective view. The wooden girder is composed of two similar wooden beams 1 and 2, which are arranged in parallel and at a certain distance. The wooden beams are joined by means of a layer of polyurethane foam 3 placed between the wooden beams. In such a way a wooden girder is made and the length of it is determined of the length of the wooden beams 1 and 2 and the depth of the web h is deter- mined by a width of the wooden beams and the distance between the wooden beams. The dimensions of the cross- section of the wooden beams and the depth of the web gives the strength of the composed wooden girder. The depth of the web determines the width of the spacing element 3 and thus the amount of polyurethane foam. The insulating capacity of the wooden girder in the direc¬ tion of the depth of the web is thus determined by the amount of polyurethane foam and it is understood that the insulating capacity is much greater in that the spacing element is of polyurethane foam than if the spacing element was of wood as for instance slab of wood, particle board or the like. The dimensions of the wooden girder may be varied by varying the distance between the wooden beams and the cross-section of the wooden beams. The wooden girders thus can be adapted to the wanted thickness of the waJ.ls when the wooden girders are used as supporting element in vertical direction. The wooden girder can of course also be used in the horizontal direction in walls.

The manufacture of the wooden girder according to the invention can be done in different ways and one prefer¬ red embodiment will be described in the following. A specific fixture, shown in Fig. 2 will be used. The fixture consists of a box shaped part 4 and a turnable cap formed part 5. The cap formed part 5 can be turned onto the box part 4 and will thus be placed according to a position shown by broken lines in Fig. 2. A number of wooden beams 1 are placed in the box shaped part 4 side by side so that a layer of wooden beams are formed in the bottom of the box shaped part. A second number of wooden beams 2 are also placed in the cap shaped part 5 so that a second layer is formed in the bottom of the cap shaped part 5. Thereafter, the cap formed part 5 is turned onto the box shaped part 4 and by means of the two layers of wooden beams and the sides of the box shaped part a closed space is formed, which space there¬ after is filled with the polyurethane material. The poly¬ urethane material is allowed to cure and adhere to the beams whereby is constituted astructural member where the wooden beams 1 and 2 form two sides being joined by the polyurethane foam 3. The composed wooden structural construction is taken out from the fixture. A part of a cross-section of such a composed wooden structure is shown in Fig. 3. In order to form the wooden girders a number of cuts are taken up in parallel to the longitudinal direction of the wooden beams and at right angle to the two layers. These cuts are shown by broken lines in Fig. 3 being indicated by 6.

The wooden beams 1 and 2 have preferably similar cross- section and are so placed in the fixture, that the cuts 6 are taken up in the parting plane between the wooden beams. However, it should be understood that the wooden beams may have different dimensions. Thus, it is obvious that the dimensions of the wooden beams may be different from beam to beam and that different dimensions can be used for the beams in the box-shaped fixture and¹in the cap formed fixture and that also the cuts can be taken up through the partition between the beams or at arbitrary places. On the other hand the length of the wooden beams shall be similar and--o"y correspond to the wooden girder, which shall be manu¬ factured.

Claims

CLAIMS :

1. Wooden girder for building purpose consisting of two parallel wooden beams having a spacing element there¬ between, which is of heat isolating material and forms the web of the girder, characterized in that the spacing element (3) is polyurethane foam and that the binding between the wooden beams (1,2) consists of the adherence of the polyurethane to wood in that the polymerization is carried out with the polyurethane contacting the faces of the wooden beams which are turned to each other.

2. Method for manufacturing of wooden girders comprising two parallel wooden beams having a spacing element between which is of heat isolating material forming the web of the girder according to claim 1 , characterized in that a number of wooden beams are placed side by side to form a layer in a box shaped fixture, and that a second number of wooden beams are placed side by side to form a second layer in a cap shaped fixture which is adapted to the box shaped fixture, that the cap formed fixture is turned on to the box formed fixture so that a closed space is formed between the two layers and the confining sides of the fixtures, in which space polyurethane foam is inser¬ ted for polymerization and for binding the two layers together, whereafter the two thus joined layers are parted into pieces by means of a number of parallel cuts, each of which are parallel with the longitudinal direc¬ tion of the wooden beams and at right angle to the layers of the wooden beams.

3. Method according to claim 2, characterized in that the wooden beams have the same width in the plane of the layers and that the cuts are made in the partition between adjacent wooden beams.