Abstract:
A wall element, comprising two outer layers extending at least substantially parallel to each other, between which two or more intermediate layers are provided, characterized in that said intermediate layers extends between the outer layers in a zigzag fashion, wherein the intermediate layers are arranged in a nested fashion.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation-in-part of co-pending U.S. patent application Ser. No. 10/617,430, filed Jul. 11, 2003, which application is herein incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to a wall element, comprising two outer layers extending at least substantially parallel to each other, between which at least one intermediate layer is provided. The invention furthermore relates to a method for manufacturing said wall element.  
         [0004]     2. Description of the Related Art  
         [0005]     A prior art wall element is known from German patent no. 2 026 768 (Universal Papertech Corp.). Said patent discloses a building which is built up of many different constructional elements, such as a concrete floor, roof parts and sidewall parts made of a corrugated board intermediate layer, which is sandwiched between two flat outer layers, as well as clamps and corner elements. In practice it has become apparent that the constructional strength of the roof parts and the side wall parts is insufficient to give the building the required strength.  
       SUMMARY OF THE INVENTION  
       [0006]     The object of the invention is to improve the wall element that is known from the aforesaid German patent publication, in the sense that a wall element is provided which exhibits an optimum constructional stiffness for functioning as a constructional element of a building, as a wall panel in a partition, etc. It is noted that the term wall element is understood to include an element for a wall, a floor, a ceiling, a roof, etc.  
         [0007]     In order to accomplish that objective, a wall element of the kind referred to in the introduction is characterized in that said intermediate layer extends between the outer layers in a zigzag fashion, wherein the parts of the intermediate layer that extend from one outer layer to the other are at least substantially flat. Research has shown that the present zigzag shape results in an unexpectedly great constructional stiffness of the wall element, so that the wall element can be exposed to large forces without losing its structural integrity. The constructional strength is additionally increased if the part extending from one outer layer to the other extend at an angle of less than 90°, preferably between 30° and 75°, more preferably between 45° and 65°.  
         [0008]     In one preferred embodiment of a wall element according to the invention, the parts extending from one outer layer to the other bound a flat portion of the intermediate layer, which abuts against an outer layer over a distance of 0-5 cm, preferably 0-3 cm, more preferably 0-2 cm. On the one hand the presence of the flat (intermediate) portion makes it possible to affix said portion to an outer layer, in order to increase the stiffness of the whole, but on the other hand, the distance over which the flat (intermediate) part is affixed to an outer layer in that case must remain within the indicated bounds, in order to prevent the whole from collapsing in an “accordion-like” fashion upon being loaded.  
         [0009]     In another preferred embodiment of a wall element according to the invention, the parts extending from one outer layer to the other form a fold having a radius of less than 10 mm, preferably less than 5 mm, with each other. In other words, the magnitude of radius of the bend between parts extending from one part of the outer layer to the other is within the indicated bounds, which contributes to an optimum strength of the wall element.  
         [0010]     In another preferred embodiment of a wall element according to the invention, said intermediate layer is at least substantially made of a material selected from the group of corrugated cardboard, massive cardboard and wood.  
         [0011]     In another preferred embodiment of a wall element according to the invention, said outer layers are at least substantially made of a material selected from the group of corrugated cardboard, massive cardboard and wood. In particular, said intermediate layer and/or said outer layers is (are) at least substantially made of corrugated cardboard exhibiting a crimped surface profile, so that said intermediate layer and/or said outer layers can hardly be deformed, if at all, in any direction along their surface.  
         [0012]     Preferably, said intermediate layer is formed of layers of paper/cardboard, wherein each layer is at least substantially made up of a corrugated sublayer and a flat sublayer affixed to one side thereof, wherein said paper/cardboard layers are interconnected via an adhesive, in particular a glue, which is present on the ridges of the corrugated sublayers. In a special embodiment, said intermediate layer can also be made up of a corrugated sublayer, wherein the two flat sublayers and the corrugated sublayer present therebetween are interconnected by means of an adhesive, in particular a glue, which is present on the ridges of said corrugated sublayer. In a preferred variant, also said outer layers are made up formed of layers of paper/cardboard, wherein each layer comprises a corrugated sublayer and a flat sublayer present on one side thereof, wherein an adhesive which is present on the ridges of the corrugated sublayers provides the interconnection of the paper/cardboard layers. In another preferred variant, said outer layers are made of wood. In yet another preferred variant, said outer layers are each made up of a gypsum board, which is built up of two paper/cardboard external layers, with an internal gypsum layer present therebetween. Said gypsum board can be connected to the intermediate layer of the present wall element either directly or with the interposition of a paper/cardboard layer, as will be explained yet hereinafter with reference to the drawing.  
         [0013]     It is noted that the term paper is used for lighter sorts of paper, whilst the term cardboard is frequently used for heavier classes of paper. Within the framework of the invention no restriction as regards the sort of material is intended when the terms paper or cardboard and weight are used.  
         [0014]     In another preferred embodiment of a wall element according to the invention, said wall element is arranged for accommodating piping, cables and the like and/or insulation material and/or stiffening material in the intermediate layer thereof. In itself the present wall element exhibits an ideal thermal insulation, on account of the relatively large air cavities in the zigzag intermediate layer, but said cavities can also be utilized, partially or entirely, for accommodating piping, cables and tubes or for insulation and/or stiffening material.  
         [0015]     The invention furthermore relates to a method for manufacturing a wall element according to the invention, which method comprises the steps of: 
        pressing a strip of a starting material, which is at least substantially made of cellulose, against a mould having a zigzag surface for the purpose of pressing a zigzag shape in said strip of starting material so as to form the intermediate layer;     subsequently affixing the outer layers, which are at least substantially made of cellulose, to both sides of the intermediate layer.        
 
         [0018]     Preferably, the intermediate layer is affixed to a carrier as a semi-finished product. This makes it possible to roll up the whole of intermediate layer and carrier into a roll and affix the outer layers to the intermediate layer at a later stage.  
         [0019]     In one preferred embodiment of a method according to the invention, the strip of starting material is positioned relative to the mould by means of an underpressure between the strip of starting material and the mould.  
         [0020]     The invention furthermore relates to a device for carrying out a method according to the invention, wherein a mould having a zigzag surface is provided.  
         [0021]     In another embodiment, there are two separate intermediate layers which are each connected to an outer layer of the wall element. Typically each outer layer has a portion of one of the intermediate layers attached to it at a location where the intermediate layer runs parallel to the outer wall. The intermediate layer extends from the outer layer and forms an apex, or peak, which may attach to the opposite wall element. The apex, or peak, can be a point or a flat surface. The other wall element is a mirror image of the first wall element, but is arranged so that the intermediate layers interlock and are “nested,” one within the other. Thus, each intermediate layer is attached to one outer layer initially and when the wall is constructed the other end of the intermediate layer, at the apex or peak, can be affixed to a valley of the other intermediate layer.  
         [0022]     The invention furthermore relates to a method for manufacturing a wall element wherein, the method comprises the steps of: pressing a strip of a starting material against a mould having a zigzag surface for the purpose of pressing a zigzag shape in said strip of starting material so as to form intermediate layers; affixing each outer layer, to one side of one intermediate layer; and joining the two intermediate layers. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]     The invention will now be explained in more detail by means of preferred variants of the invention as shown in a drawing, wherein:  
         [0024]      FIGS. 1 and 3  are schematic, perspective views of two embodiments of a device according to the invention from manufacturing a wall element according to the invention;  
         [0025]      FIG. 2  shows a detail of  FIG. 1 ;  
         [0026]      FIGS. 4-7  are schematic, perspective views of various embodiments of wall elements according to the invention;  
         [0027]      FIGS. 8 and 9  relate to two ways of connecting a wall element according to the invention to a structural section;  
         [0028]      FIGS. 10 and 11  show to further embodiments of a wall element according to the invention; and  
         [0029]      FIG. 12  is a schematic, perspective view of a building which is built up of wall elements according to the invention.  
         [0030]      FIG. 13  is a schematic, perspective end view of another embodiment of the invention.  
         [0031]      FIG. 14  is an exploded view of  FIG. 13 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0032]      FIG. 1  shows a mould  1  according to the invention, comprising an endless, circulating belt  2 , on which belt elements  3  of triangular cross-section are present Mould  1  furthermore comprises two driving rollers  4 ,  5  for driving a chain  6 , which is connected to belt  2  via pins  7 , and which consequently drives said belt. As is, shown in more detail in  FIG. 2 , pins  7  support the belt elements  3 , whereby the latter are hollow and provided with perforations  8  on their outer surface. This makes it possible to position a strip of corrugated cardboard  9  from a supply roll (not shown) precisely with respect to belt  2 , whereby an underpressure (in particular a vacuum) is generated in the hollow belt elements  3  via a pipe  10  so as to press/suck the strip of corrugated cardboard down onto belt  2 , as it were. As is shown in  FIG. 1 , a rotary pressure element  11  of a star-shaped cross-section is used to press the strip of corrugated cardboard  9 , which is moved past a hold-down roller  12 , down on the belt  2  of the mould  1  with a suitable force and thus press a zigzag shape corresponding to the outer surface of the mould  1  into the strip of corrugated cardboard  9 . The strip of corrugated cardboard  9  in its final zigzag shape forms and intermediate layer of a wall element according to the invention, as will be explained in more detail hereafter. Once the zigzag intermediate layer has been formed, corrugated cardboard outer, layers can directly be glued to both sides thereof, if desired. If the zigzag intermediate layer is stored as a semi-finished product, however, it is first glued, by means of glue rollers  13 , to a paper carrier  15  from a storage roll (not shown) which is carried past a hold-down roller  14 , after which the whole is wound into a roll  16 . At a later stage, said zigzag intermediate layer can be detached from carrier  15  and corrugated cardboard outer layers can be glued to both sides thereof. In  FIG. 2 , those parts that correspond to parts shown in  FIG. 1  are indicated by the same numerals.  FIG. 3  schematically show the aforesaid strip of corrugated cardboard  9  of  FIG. 1 , in which folding or banding lines  18  are first formed, as a pre-operation, by means of a cutting die  17  in order to make it possible to give the strip of corrugated cardboard  9  its zigzag shape without using the mould  1 . To this end, the strip of corrugated cardboard  9 , once it has undergone the cutting operation, is moved along a guideway  9 , which converges in the direction of movement of the strip of corrugated cardboard  9 . Due to the natural weakness of the material of the corrugated cardboard, the folding lines  18  and the tapered or conical shape of the guideway  19 , the zigzag shape is automatically obtained in the strip of corrugated cardboard  9 , as it were. In order to realize a controlled guidance of the strip of corrugated cardboard  9 , guide wheels  20  are used. After the formation of the zigzag intermediate layer, the aforesaid corrugated cardboard outer layers  21  are glued to both sides thereof.  
         [0033]      FIGS. 4, 5  and  6  are perspective views of various types of wall elements  22  according to the invention wherein each type comprises a zigzag intermediate layer  23  consisting of a corrugated sublayer, to both sides of which a flat sublayer is affixed. As  FIGS. 4, 5  and  6  show, the parts  23 ′ of the intermediate layer  23  that extend from one layer to the other are flat, so as to give the wall elements  22  an optimum strength. The outer layers  21  of the wall elements  22  of  FIGS. 4, 5  and  6  are each built up of several layers of cardboard, each layer consisting of a corrugated sublayer, and a flat layer glued to one side thereof by means of a glue applied to the ridges of the corrugated sublayer. Wall element  22  pf  FIG. 6  is curved, with pipes  24  being passed through the intermediate layer  23  thereof, whilst the outer layers  21 , just like the outer layers of wall element  22  of  FIG. 5 , are in fact formed by using a winding process wherein one outer layer  21  is wound around the intermediate layer  23  several times.  
         [0034]      FIG. 7  is a perspective view of another variant of a wall element  22  according to the invention, which clearly shows that the intermediate layer  23  is built up of a corrugated sublayer  27  which is sandwiched between flat sublayers  25 ,  26 , whilst the outer layers  21  comprise three glued-together layers of corrugated cardboard, which are each built up of a corrugated sublayer and a flat sublayer affixed to one side thereof, wherein glue is present on the corrugations of the corrugated sublayer. Depending on the required strength, it is also possible to form the intermediate layer  23  and/or the outer layers  21  of more layers than in the illustrated example. The parts  23 ′ of the intermediate layer  23  that extend from on outer layer  21  to the other bound a flat portion  23 ″ of the intermediate layer  23 , which flat portion  23 ″ abuts against the respective outer layer  21  over a distance of 2 cm, in this embodiment, and which is glued together therewith.  
         [0035]     A wall element  22  according to the invention can readily be used in a building structure, wherein the wall element  22  is inserted into a metal H-section  28  ( FIG. 8 ), for example, or into a metal section  29  having a more complex shape ( FIG. 9 ). The wall element  22  of  FIG. 9  is filled with the insulation material  30 . It is also possible to use a strengthening material instead of such insulation material.  
         [0036]      FIG. 10  relates to a preferred variant according to the invention, wherein a wall element  22 , for example the wall element that is shown in  FIG. 4, 5 ,  6  or  7 , comprises a gypsum plate  31  on both sides, which is affixed thereto. Since the gypsum plates  31  are offset with respect to wall element  22  as it were, the whole, which functions as a constructional element, comprises a through channel  32  at one end side and a projecting part  33  of wall element  22  at the other end side, so that such constructional elements can be easily interconnected by inserting the projecting part  33  of on constructional element into the through channel  32  of the other constructional element,  FIG. 11  corresponds to  FIG. 10 , with parts corresponding to parts shown in  FIG. 10  being indicated by the same numerals, but wherein the intermediate layer  23  is directly connected to the gypsum plates  31  on both sides, that is, without the additional outer layers of  FIG. 10  being used. In that case, the paper/cardboard outer layers of the gypsum plates  31  that face towards the intermediate layer function as the “outer layer”  21  for the intermediate layer  23 ″, as is shown in  FIG. 11 . Instead of forming the wall element  22  with a projecting part on one side ( FIG. 10 ), it is also possible, of course, to use a separate beam  34  ( FIG. 11 ), for example made of wood, which projects from between the gypsum plates  31 .  
         [0037]      FIG. 12  is a perspective view of a building, wherein wall elements  22  form the eventual walls  35 , a floor  36  and a (curved) ceiling  37 . Use is made of sections  28  thereby, which sections are so configured that the wall elements  22  can readily be received therein, for example by sliding.  
         [0038]      FIG. 13  is an exploded end view of another embodiment of a wall element  220 . In this embodiment wall element  220  consists of two constructional parts  110 ,  210 . Each one of the two constructional parts  110 ,  210  consist of an outer layer  100 ,  200  and an intermediate layer  105 ,  205 . The intermediate layers  105 ,  205  and the outer layer can be made of various materials (for example; card board, wood, cellulose material, gypsum, sheetrock, metal, plastic, fiberglass, etc.). The outer layer  100 ,  200  is substantially flat or planar. The intermediate layers  105 ,  205  are initially planar, but are shaped into a zigzag fashion shown in the figure. While the zigzag fashion is illustrated as having defined corners it should be appreciated that the layers could be formed into curved members and configured as a sinusoidal wave. In the embodiment of  FIG. 13 , the zigzag of the intermediate layers  105 ,  205  forms of valleys  101 ,  201  between peaks,  103 ,  203  which are connected by side walls,  102 ,  202 . The bottom surface  104 ,  204  of each valley  101 ,  201  is affixed to an outer layer  100 ,  200 , to form the constructional part  110 ,  210 , by any means (for example glue, adhesives, nails, screws, etc.). The valleys  101 ,  201  can be of any length so long as the peaks  103 ,  203  fit between the side walls,  102 ,  202  of the other constructional part  110 ,  210 . Each constructional part  110 ,  210  is a mirror image of the other constructional part  110 ,  210 .  
         [0039]      FIG. 14  is an end view of the assembled wall element  220  from  FIG. 13 . The two construction parts  110 ,  210 , of  FIG. 13 , are joined together so that the peaks  103 ,  203  of one intermediate layer  105 ,  205  are affixed to the valleys  101 ,  201  of the other intermediate layer. The peaks  103 ,  203  can be affixed to the valley  101 ,  201  by any means (for example glue, adhesives, nails, screws, etc.). Although  FIG. 14  shows the peaks  103 ,  203  being fixed to the valley  101 ,  201  it should be appreciated that the intermediate layers  105 ,  205  could be affixed at the side walls,  102 ,  202 . As assembled, the peaks  103 ,  203  nest into the valleys  101 ,  201  of the opposite intermediate layer  105 ,  205 , and the outer layers  100 ,  200  enclose both intermediate layers  105 ,  205 .