Beam
The present invention relates to a flanged beam with a web structure formed of wire or strip-like members bent into zigzag, meander or wave shape and having their bending points secured to the flanges. 
     BACKGROUND 
     A beam of this type and a method of manufacturing it is described in e.g. Swedish Lay-Open Print No. 7610600-4. The usage of this as well as other beams is however limited by the bearing capacity and bending properties. These qualities are primarily dependent on the properties of the wooden flanges and on the degree of deformation of the wood at the points where the web of bent metal wire or strip is secured to the flanges. The wood comprised in the flanges must therefore be classified and jointed with great accuracy while complying with the stipulated rules, which is a both complicated and costly procedure. As disclosed in the published &#34;SE-B-&#34; No. 415 991, certain attempts have been made to overcome these drawbacks by attaching wire, extending in the longitudinal direction of the flanges, by welding it to the bending spots of the web. Unfortunately however, this has resulted in productional complications setting aside the economical profit gained by the increased rigidity and bearing capacity of the beam, despite the advantage that a lower quality of wood can be used for the flanged. In fact, welding of the wire extending along the flanges to the bending points of the web must necessarily take place prior to the anti-corrosive treatment of the wire included in the web structure, which treatment cannot be neglected. Beyond being expensive per se as it must be performed individually for each separate unit of the almost lattice-resembling webs created by the wire members welded to the bending points, this anti-rust treatment also eliminates the possibilities of rationally manufacturing finished webs by the continuous bending of an already surface-treated wire taken directly from a supply coil. 
     SUMMARY OF THE INVENTION 
     The object of the invention is therefore to suggest a novel and improved type of beam in accordance to what is set forth by way of introduction, which solves the above-described problems associated with the previously known beams and which, despite its more solid and deformation-resistant structure, enables a simplified and less expensive manufacture of beams than has been possible so far. 
     In order to fulfill its purpose at least in all essential parts, a beam constructed according to the invention is mainly characterized in that at least one flange has a section extending longitudinally with the flange and consisting of another material than the rest of it, and which is embedded in the flange while being cast to form an integral unit therewith and with the bending spots of the wire or strip-like member fixed thereto. 
     By means of embedding flange sections into the beam flanges, these sections thereby forming a unit not only with the flange but with the web as well, this web structure can be manufactured in a most simple manner from already surfacetreated wire or strip material taken from a storage coil, the invention simultaneously safeguarding a particularly stable deformation-reluctant connection between the bending points of the web and the flanges. 
     A further, especially important advantage gained by the invention is that the main part of the rigidity and the supporting capacity of the completed beam can, if desired, be transferred to the embedded flange sections, whereas the design of remaining flanges and the material selected therefor can be adapted primarily for nailing and screwing, temperature insulation or any other desirable purpose. As a consequence for example, the quality of the wooden flanges need not be too high, and neither the classification nor the splicing or jointing of the wood need be done with the aid of any sophisticated or costly methods. With the appropriate dimensions and a suitable material selected therefor, the embedded flange sections will constitute the elements taking up most of the load in the beam, relieving in this way the wooden material in the flanges from the greater part of its load-bearing function. In ordinary building beams there are required for this purpose only comparatively small crosssectional areas for the flange sections. Sectional areas as small as one or a few square centimeters will in fact afford considerable reinforcing effects to the beam. 
     In a preferred embodiment of a beam performed according to the invention, at least the main part of the embedded flange section is disposed in a long channel or groove-like space in the flange, accommodating at least partially the wire or strip-like portions joined to this flange. Without applying the elaborate procedure of wood classification and preparation of wood/metal wire connections associated with the previously known beams, similar beams can be manufactured according to the invention simply by providing a channel or groove along the whole length of the wooden flanges, said groove then serving as a mould when applying the other material intended to form the embedded flange section in accordance with the invention. 
     In order to ascertain a really efficient cast integration between the embedded flange section and the portions of the web-forming wire or strip-like members disposed inside a flange, the long groove-like space has a bottom which is in communication with additional spaces intended for these web portions. 
     The section embedded in a flange and consisting of another material than the rest of the flange can either be disposed on the side of the flange facing away from the web, or on the side facing towards it. In the latter case the other flange sections will be more easily accessible for nailing and screwing for example, whereas in the former case the embedded flange section has a more active load-absorbing function due to its placement further away from the so-called neutral surface of the beam. 
     As embedded flange section of the inventive kind can be made from a variety of compounds of which several plastics with the appropriate amount of fillers seem to be the most useful materials at least for beams in building constructions, and the flanges themselves can be made of wood or the like material fitted for nailing and screwing. Examples of suitable plastics are polyester, acrylate, polyurethane, epoxy resin or similar compounds, which may preferably be reinforced with steel or glass fibre, mica or any other material contributing to the strength of the embedded flange section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be explained in more detail below while referring to an exemplary embodiment of the inventive beam, shown on the drawing. 
     FIG. 1 in the drawing is a partially cut away perspective view of a beam according to the invention, primarily intended for use in the building industry, whereas 
     FIGS. 2-4 are three cross-sectional views of such a beam. 
    
    
     DETAILED DESCRIPTION 
     As can be seen from the drawing, a beam according to the invention has two chords or flanges 1 interconnected by a web structure, the beam therefore being regarded as a type of I-beam. The web structure however is formed of a wire or strip-like member 2 bent for example into zigzag, meander or wave shape and having its bending points 3 connected to the flanges 1, the similarity to a conventional I-beam therefore being incomplete. 
     According to the invention, the two flanges 1 include a long flange section 4 made of another material than the rest of the flange and extending along the length of each respective flange while being embedded therein and cast to form an integral part of the flange and of the bending points 3 of the wire or strip-like member 2, which points are also connected to the flange. 
     The wire or strip-like member 2 in the embodiment of the inventive beam consists of properly dimensioned steel wire which is bent to the illustrated configuration after having been treated with the necessary anti-corrosive agent. In order to permit screwing and nailing, the main part of the flanges are preferably made of wood, for example studs measuring 2×2&#34;. Alternatively, different kinds of wood fibre or chip material can be used for this purpose. In the present embodiment, the flange sections 4 embedded in the flanges 1 may preferably consist of a plastics material mixed with a certain amount of filler and reinforced in order to make the finished, embedded flange section sufficiently strong for taking up at least the main part of the load to which the beam may be subjected during use. Examples of plastics materials useful for the embedded flange section according to the invention are polyester, acrylate, polyurethane, epoxy resin or similar compounds, whereas steel or glass fibre, mica or the like are suitable reinforcement agents. 
     As shown in the drawing, the embedded flange sections 4 are at least principally disposed in long spaces formed as grooves 5 in the flanges 1, said grooves or spaces 5 partially accommodating those portions of the web-forming, wire or strip-like member 2 which are united with the flanges. For casting together these web portions with the flange sections embedded in the flanges, the long channel-like spaces 5 have a bottom to which are connected further recesses 6 for the portions of the web member 2 disposed inside the remaining flange portion. 
     In the embodiment shown here, exemplifying a beam performed according to the invention as illustrated in FIGS. 1 and 2, the embedded flange sections 4 are located at the sides of the flanges 1 facing away from the web 2. As can be seen from the flange cross sections illustrated in FIGS. 3 and 4 however, they can alternatively be placed on the sides of the flange 1 directed towards the web 2, or even such that one embedded flange section 4 is situated on the side of one flange 1 facing away from the web 2, whereas the embedded flange section 4 of the opposite flange 1 is situated on the side thereof turned towards the web 2. 
     The invention is not restricted to the example described and illustrated herein but can be modified in many ways within the scope of the following claims.