More particularly, the invention relates to such a floor structure component of the kind comprising a structural body, consisting at least substantially of wood.

In previously known prefabricated floor structure components of said kind, the structural body has usually been formed either by a plate-shaped member, consisting of a plurality of laminations of solid wood, placed in side-by-side relationship, or by a box-like construction, consisting of one upper and one lower plate of solid wood, connected to each'other by means of a plurality of connecting members, placed between the two plates.

A disadvantage of floor structure components com- prising a structural body of any of the two kinds above described is that the consumption of material for the production of-the structural body, required in order to achieve such a body having a satisfactory bending rigidity, is very high. Besides high material costs, this also results in that the finished floor structure component will have a high weight which makes it diffi- cult to handle the finished component, for instance in connection with the transportation thereof to a building site and the installation thereof at said site.

Another disadvantage of the known floor structure components is that the structural body has a tendency to swell or shrink in a direction perpendicular to its longitudinal direction when subjected to variations in moisture and temperature.

The invention has for its purpose to provide an improved prefabricated floor structure component of

the kind initially specified which makes it possible to avoid or at least substantially reduce the above disadvantages of the previously known floor structure components.

The floor structure component, according to the invention proposed for said purpose, is primarily charac- terized in that the body comprises an elongate glued multi-layer plate of wood, consisting of at least one layer, containing fibres extending at least substantial- ly in the longitudinal direction of the plate, and at least one layer, containing fibres extending at least substantially in the transversal direction of the plate, and a plurality of elongate stiffening members which are located beneath said plate and are rigidly connected thereto and which extend in the longitudinal direction of the plate and are located spaced apart in the trans- versal direction of the plate and which define downward- ly open longitudinally extending pockets therebetween.

The above building-up, of the structural body makes it possible to attain a considerable reduction of the consumption of material in connection with the production of the body and, hence, also a corresponding reduction of the weight of the finished floor structure component. Additionally, it also eliminates the risk of any swelling or shrinkage of the body in a direction perpendicular to its longitudinal direction under the influence of moisture and temperature variations, exist- ing in connection with the known floor structure compo- nents.

According to a preferred embodiment of the inven- tion, said plate may suitably consist of three layers, namely one upper and one lower layer, both of which contain fibres extending at least substantially in the longitudinal direction of the plate, and one interme- diate layer which contains fibres extending at least

substantially in the transversal direction of the plate.

The stiffening members may preferably be connected to said plate by means of glue joints.

Furthermore, the stiffening members may suitably comprise upright web portions which are rigidly connec- ted to said plate at their upper ends, and flange por- tions which are rigidly connected to said web portions and project laterally from the web portions at the lower ends of the latter, In this case, the stiffening mem- bers may be formed by separate web and flange members which are rigidly connected to each other, preferably by means of glue joints.

In order to facilitate an additional reduction of the consumption of material in connection with the production of the structural body and hence also of the weight of the finished floor structure component, each stiffening member may consist of two or more dis- crete web members which are located spaced apart along the length of the stiffening member, and at least one flange member, connected to each of said web members and extending along the entire length of the stiffning member.

-If instead, each stiffening member comprises a web member which extends along the entire length of the stiffening member, a weight reduction may be ob- tained by providing the web member with a series of through openings, located in spaced apart positions along the length of the web member.

As a consequence of the above described manner of building up the structural body, the floor structure component is well suited for use in a floor structure which should be capable of providing a considerable attenuation of impact sounds and other low frequencey sounds.

If the floor structure component is intended to

form part of such a floor structure, it may also com- prise a filling of sound-absorbing material, placed in said. pockets of the body,. Additionally, it may also comprise a plate which is located beneath and carried by the structural body and which, upon an installation of the floor structure component in a building, can serve as a ceiling member in a room located under the floor structure component.

Said plate may preferably be arranged to be carried in a vertically resiliently movable state at some dis- tance below the body by spring means acting between the. body and said plate. In order, during the storage and transportation of the floor structure component, to avoid that said spring means may be subjected to . damages or permanent deformations as a consequence of any forces then applied on them, the spring means may suitably be formed and arranged in such a manner, that, prior to the installation of the floor structure compo- nent, said plate can assume a position in which it lies in close contact with-the body and does not apply any forces on said spring means. Since the spring means are intended, after the installation of the floor structure component, to carry said plate at some distance below the body, they may preferably be arranged to be subjec- ted to forces applied thereon from said plate only when the plate has moved a short distance from its said posi- tion in which it lies in close contact with the body.

In order to make it more easy to handle the floor struc- ture component in connection with the storage, trans- portation and installation thereof, said component may preferably also comprise means for releasably locking said plate in a position in which the plate lies in close contact with the body.

As an alternative to the use of special spring means for carrying the plate below the body, it should

be mentioned that the plate may be secured to the body at two opposite ends thereof, while it is freely sus- pended between its said two ends.

The invention also relates to a method for the production of the floor structure component above des- cribed. This method is primarily characterized by con- necting said plate of wood and said stiffening members of the structural body to each other through a glueing operation which is carried out in a glue press and du- ring which said plate is supported resting in an inver- ted position on a bearing surface of the glue press and the stiffening members are placed in inverted posi- tions on said plate and pressed downwardly against the plate by press means applied against upwardly facing surfaces of said members.

After the glueing operation carried out in the glue press, the structural body may, if so required, be transferred to one or more following working stations, in which said body, while still being in an inverted state, is subjected to a subsequent machining operation and/or is supplemented with additional means, intended to form part of the finished floor structure component.

Below, the invention is further described with reference to the accompanying drawings, in which:- Figure 1 shows a partial perspective view of a prefabricated floor structure component according to a first embodiment of the invention, selected by way of example only, Figure 2 shows a corresponding view of a prefabri- cated floor structure component according to. a second embodiment of the invention, also selected by way of example only, Figure 3 shows a partial view on an enlarged scale, illustrating how a lower plate forming part of the floor structure component according to Figure 2 may be sus-

pended in a structural body of said component located above said plate, Figure 4 shows a partial view in section taken along line IV-IV in Figure 3, Figure 5 shows an end view of a glue press utili- zed for the production of the structural body of the floor structure component, Figure 6 shows an end view illustrating a later stage during the production of the floor structure com- ponent according to Figure 2, Figure 7 shows a partial end view of the structu- ral body of the floor structure component, illustrating an alternative design of a stiffening member forming part of said component, Figure 8 shows a partial sectional view corres- ponding to Figure 4 but illustrating a modified design of the means serving for suspending the lower plate from the structural body of the floor structure component, Figure 9 shows a perspective view, seen in an inclined direction from below, of a floor structure component according to a further embodiment of the in- vention, and Figure 10 shows a partial view in section and on an enlarged scale of the floor structure component accor- ding to Figure 9.

As a whole, the floor structure component shown in Figure 1 forms a structural body, generally designa- ted 10. The body comprises an elongate generally rec- angular plate 11 of wood and a plurality of elongate stiffening members 12 which are located beneath said plate and are rigidly connected thereto and which extend parallel to each other in the longitudinal direction of plate 11 and are located spaced apart in the transversal direction of the plate. Hereby, stiffening members 12

define a number of downwardly open longitudinally ex- tending pockets 13 therebetween.

Plate 11 consists of a glued multi-layer plate of wood, comprising three layers 14,15 and 16 of solid wood. The upper and lower layers 14 and 16, respective- ly, contain fibres extending at least substantially in the longitudinal direction of plate 11, while the inter- mediate layer 15 contains fibres extending at least substantially in the transversal direction of plate 11.

As a result of its said composition, plate 11 will have a very high shape stability. Layer 15 will counteract any tendency of the plate to swell or shrink in a direc- tion transverse to its longitudinal direction under the influence of occurring moisture and temprature variations, while it simultaneously yields a high bending rigidity to the plate.

Stiffening members 12 consist of upright web mem- bers 17, which by means of glue joints, are rigidly con- nected to plate 11 at their upper ends, and flange mem- bers 18 which, by means of glue joints, are rigidly con- nected to the web members and project laterally from the web members at the lower ends of the latter. In the embodiment shown in Figure 1, web members 17 as well as flange members 18 consist of solid wood and extend continuously along the entire length of plate 11. However, for the purpose of saving material and reducing the weight, as shown in Figure 2, each web mem- ber may instead consist of a plurality of short sections 17'which are placed in spaced apart positions along the length of the stiffening member. Alternatively, as indicated in dash-dotted lines in Figure 1, each web member 17 may be provided with a series of through ope- nings 17", located in spaced apart positions along the length of the web member.

At its lower side, plate 11 is provided with

shallow longitudinally extending grooves 19 which receive upper end portions of web members 17 extending into said grooves. Furthermore, at each of its two longitudi- nal lateral edges, plate 11 is provided with a longitu- dinally extending groove 20. When mounting floor struc- ture component 10 in a building, this groove serves to faciliate an interconnection between the two plates 11 of two adjacent floor structure components by means of a filling, inserted into the adjacent grooves 20 of said two plates.

In addition to a structural body 10 of the kind shown in Figure 1, the floor structure component shown in Figure 2 also comprises a filling 21 of sound-absor- bing material, e. g. mineral wool, placed in each pocket 13. Moreover, it also comprises a plate 22 which is lo- cated beneath body 10 and which is resiliently suspended from stiffening members 12 and intended, upon an installa- tion of the floor structure component in a building, to form a ceiling member in a room located under the floor structure component.

As shown more in detail in Figures 3 and 4, plate 22 may for instance be resiliently suspended from stiffe- ning members 12 by means of leaf springs 23, bent into a U-shape and placed in spaced apart positions along the length of the stiffening members and carrying chan- nel-profile metal members 24, partially received in longitudinal grooves 25, provided at the lower ends of the stiffening members. In the illustrated case, leaf springs 23 have been assumed to be secured to members 12 by means of screws 26 and to members 24 by means of rivets 27. Furthermore, plate 22 has been assumed to be secured to profile members 24 by means of screws 28.

In Figure 2, plate 22 has been shown to extend right up to the shown short end of body 10. In practice,

the ends of plate 10 as well as the ends of profile members 24 may however be located at some distance be- hind the ends of the body in order hereby to make it possible, in connection with the installation of the floor structure component in a building, to place said component resting on suitable supports by means of un- covered end portions of stiffening members 12.

Below, a method for the production of the floor structure component shown in Figure 2 is briefly described with reference to Figures 5 and 6.

A plate-shaped multi-layer member 11', intended to form plate 11, is placed in an inverted position on a bearing table 29 in a glue press 30. Prefabricated stiffening members 12 are then placed in an inverted state in the intended positions on member 11'which in advance has been provided with grooves 19. Before pla- cing members 12 upon member 11', glue is applied in grooves 19 and/or on the end portions of members 12 in- tended to be inserted into said grooves.

Press power is then applied on the upper ends of members 12 by means of a vertically movable press plate 32, operated by hydraulic cylinders 31. At its lower side, said press plate is provided with projecting por- tions 33 which can be applied under pressure against upwardly facing surfaces of members 12 and which simul- taneously can serve as guide means for members 12, hold- ing said members oriented in their intended positions during the pressing operation. When the glue has set, press plate 32 is lifted, whereupon member 11'and the members 12 now rigidly connected thereto are., removed from press 30. The product thus obtained may then be subjected to a subsequent machining operation during which member 11'is given a final shape corresponding to the desired shape of plate 11. Grooves 20 may suita- bly be produced during this subsequent machining opera-

tion.

The product produced through the method above described corresponds to the structural body 10 of a floor structure component shown in Figure 1. While still being in an inverted position, in a manner indicated in Figure 6, body 10 may be provided with the required supplementary parts to form a composite floor structure component according to Figure 2. In this connection,. the desired fillings 21 are inserted into pockets 13 and the profile members 24 along with the spring 23 previously secured thereto are affixed to stiffening members 12.

Furthermore, if so desired, additional parts may be fitted on to body 10. For instance, installations of various kinds may be placed in pockets 13 prior to the insertion of fillings 21 into said pockets. Finally, ceiling member plate 22 is affixed to profile members 24. The floor structure component is then ready for transportation to the desired installation site.

In Figure 7, there is shown a stiffening member of a slightly modified design. In this case, the stif- fening member consists of a web member 17 and a flange member 18'located beneath the web member. Web member 17-is connected to plate 11 and flange member 18'by finger joints 34.

Figure 8 shows a modified design of the means serving for hanging up plate 22 in the structural body of the floor structure component. While spring 23, shown in Figures 3 and 4, has its upper leg rigidly connected to stiffening member 12 by means of screw 26, the upper leg of spring 23', shown in Figure 8, is mounted for limited vertical displacement on a bolt 26', extending in a downward direction from member 12 and provided with an enlarged head at its lower end. As a consequence during the transportation and storage of the floor structure component, stiffening member 12 may rest with

its flange members 18 upon plate 22 in close contact therewith without applying any forces on spring 23'.

Hereby the spring means serving to support plate 22 will not run the risk of becoming damaged or permanent- ly deformed by any compressive forces applied thereon.

In the floor structure component shown in Figures 9 and 10, body 10 consists of a glued multi-layer wooden plate 11, composed of boards, and a plurality of stif- fening members 12 of solid wood, located beneath said plate and rigidly connected thereto and extending along the whole length of plate 11. Plate 22 consists on the one hand of a layer of boards 35 which extend in the transversal direction of the floor structure component and are connected to two upper joists 36, extending in the longitudinal direction of the floor structure compo- nent, and on the other hand of a lower cover plate 37 affixed to said boards. In Figure 9, a front portion of plate 22 has been omitted for the purpose of clarifica- tion.

Plate 22 is carried by body 10 by means of a number of elongate leaf springs 23", having mutually opposite end portions, by which they are affixed to two adjacent stiffening members 12, and intermediate portions, which serve to carry a joist 36. In Figure 10, the leaf springs have been shown affixed to members 12 through the inter- mediary of spacers 38. The purpose of this measure is to make sure that the springs will not become loaded by plate 22 until boards 35 of said plate are located at a short distance below stiffening members 12.

The invention is not restricted to the. embodiments above described and shown in the drawings. Instead, many other embodiments are feasible within the scope of the invention as defined in the following claims.