Abstract:
A connection device for connecting two structural components is comprising a retaining member in a first structural component and a fixing member for insertion in a second structural component for connecting engagement with the retaining member thereby holding the two structural components together. The fixing member comprises a plug member having a first end and a second end, the the first end comprising an undercut head for insertion in and retaining engagement with the retaining member. The plug member is comprising a member for engagement with the second structural component.

Description:
DESCRIPTION OF RELATED ART 
   WO/9200461 discloses a clamp means for connecting objects in a strong and simple way. The clamp means comprises a female part having a U-form and one or two portions extending inwards in the U and providing one or two barbs for retaining a male part extending into the female part. 
   A well known furniture connector is one which comprises an excenter groove plug cooperating with a head on a bolt. The plug is inserted in a bore in the one furniture part and the bolt is inserted through a bore in the other furniture part and engages the plug. A turning of the bolt results in a tightening of the connection. 
   There are also known snap fasteners wherein a plug having an undercut or enlarged head cooperates with a more or less resilient receptacle. 
   The first mentioned clamp means gives a simple and secure connection between two objects but is, however, dependent on tight tolerances in order to result in a stable connection. Said furniture connector gives a good and possibly later tightable connection between furniture parts but calls for a certain adaption and orientation of the plug for engagement with the bolt head. 
   Snap fasteners are simple and cheap but will mostly have a certain loosenes and they cannot be tightened at the time of connection or later. 
   It is especially for furniture important that it is possible to tighten the connectors at the time of connection and later. There is a need for a such cheap, fast and simple and tightable connector, especially for furniture. 
   BRIEF SUMMARY OF THE INVENTION 
   The object of the present invention is to provide for a such connector, especially for furniture components but also more generally for structural components. 
   This object is achieved with a connecting device as disclosed in claim  1 . Further advantageous feature are disclosed in the dependant claims. 
   The invention combines the easiness of snap fasteners with the possibility of tightening the connection. The need for close tolerances is eliminated and a connection between two structural components is realised in a releasable and tightable way. 
   Used as a furniture connector with a profile element with a longitudinal slot the invention will simplify the placing together of components and the connection can be realised in a more simple way, without specific calls for mutual adaption and orientation in that the new profile element has a slot for insertion of the plug head so that the plug and its head can be inserted in the slot provided the slot is given a fairly correct orientation relative the plug before such insertion. What it takes is that the plug must only be inserted in the profile element through the slot so that the undercut head engages behind the internal retaining engagement means. Thereafter the device can be tightened in that the tightening means is tightened, whereby the undercut head is pressed against the internal retaining engagements means and the second structural component is drawn tight against the first structural component. 
   A preferable embodiment is one where the profile element is a plate metal member which is rolled and/or bent to a sleeve form having at least on plate edge portion extending inwardly in the profile and forming the retaining engagement means. 
   Preferably the undercut head may have a groove for receiving the plate edge portion. The plate edge portion and the undercut head will then be locked together, thereby enhancing the connection. 
   Preferably the plug member may have a longitudinal dimension resulting in that the said second end will extend out from the first structural component when the undercut head is inserted and retained in the retaining means. The plug member may the have a centering or guiding function for the second structural component, an advantage when putting together two or more components, f.inst. a shelf. 
   The retaining means may have a longitudinal dimension enabling the use of more then one fixing means together with the retaining means. 
   Another preferable embodiment is one where the retaining means comprises a cylindrical body having an outer peripherical surface, a longitudinal slot extending radial inwards from said surface and ending in an enlarged cavity in said body for receiving and retaining engagement with the said head. 
   A preferable embodiment of the invention is one where the connecting device further includes a locking member adapted for insertion in locking engagement with the mutually engaged retaining means and fixing means. 
   In order to be able to release the plug member from the engagement with the retaining means, especially in connection with larger structures and connecting devices the plug member when cooperating with a profile element may have an internal bore having a diameter at least equal to the dimension across the undercut head so that the bore will opens out behind and adjacent the undercut head, thus enabling a rod or a screw, provided the bore is threaded, to push the edge portions out of engagement with the undercut plug head. 
   The orientation of the profile member in a bore in a structural component is not critical as long as the slot is fairly oriented to receive the plug head but preferably the profile element may have an outer fixating element for the cooperation with a wall in the bore. 
   The insertion of the plug head through the slot in the profile element calls normally for a certain flexibility in the plug head and/or in the profile element. Thus the profile elements and/or the plug head are provided with a certain compression and expansion potential. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Characteristics and advantages of the invention will be apparent from the following description of some embodiments, which are to be intended only as examples and not as limitations with reference to the enclosed drawings, wherein: 
       FIG. 1  shows a section of a preferred connector according to the invention; 
       FIG. 2  shows a section of a modified connector according to the invention; 
       FIG. 3  shows a section of a third preferred embodiment of the invention; 
       FIG. 4  shows a perspective view of a possible profile element according to the invention; 
       FIG. 5  shows a perspective view of an elongated profile element according to the invention; 
       FIG. 6  shows a section through a wall or fence provided by means of the invention; 
       FIG. 7  shows a section through an embodiment where the plug member may be released from the profile element; 
       FIG. 8  shows a modification of the profile element in  FIG. 4 ; 
       FIG. 9  shows a side view of the element in  FIG. 8 ; 
       FIGS. 10-12  show possible embodiments of locking members; and 
       FIG. 13  shows a section of another embodiment according to the invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to the above figures  FIG. 1  shows a preferred connector according to the invention for the connection of two furniture parts or structural components  1  and  2 . A blind bore  3  is provided in the first furniture part  1 . An opening  4  in the form of a bore extends from the side of the furniture part  1  facing the second furniture part  2  and opens into the blind bore  3 . The second furniture part  2  has a throughgoing bore  5 . 
   A profile element  6  is arranged in the blind bore  3  with the slot  9 , formed by the inwardly extending edge portions  7 , 8 , oriented towards the bore  4 . As shown the edge portions  7 , 8  provide retaining means or barbs  10  and  11 . When connecting the furniture parts  1  and  2  a plug  12  is inserted through the bore  4  and in through the slot  9  until the undercut plug head  13  is placed behind the barbs  10 , 11 , as shown in  FIG. 1 . The plug  12  has a such length that it extends into the furniture part  2  and thus may be used as a centering or orienting means to achieve a correct alignment of the furniture parts  1  and  2  with the bores  4  and  5  in alignment. A screw  14  is shown threaded in a threaded bore  15  in the plug  12 . The screw head  16  is tightened towards and against the second furniture part  2 , in a cavity  17 . 
   It will be understood that the orientation of the profile element  6  in the blind bore  3  is not critical. Important is only that the slot  9  is so oriented that the plug head  13  can enter the slot. 
   As shown the profile element  6  may have an outer guiding or fixating element  18  for cooperation with a groove  19  in the blind bore  3  or for pressing into the material in the furniture part  1 , provided the profile element  6  is dimensioned for narrow tolerance in the blind bore  3 . 
   In the profile element  6  there may be a guiding cavity  20  for fixating cooperation with the end of the plug head  13 . If additionally the portions  7  and  8  are given a convex shape corresponding to the concave flanks of the plug  12  behind the undercut head  13 , a very stable and secure connection will be achieved when the screw  14 , 16  is tightened. Broken lines indicate a locking member which will be explained later. 
   The embodiment in  FIG. 2  is a modification of the  FIG. 1  embodiment and corresponding features are given the same reference numbers to the drawing as in  FIG. 1 . The main difference is that the embodiment in  FIG. 2  has only one barb  10  whereas the other edge portion  8  is drawn down against the bottom in the profile element  6 . Correspondingly the plug head  13  is undercut only on one side, for cooperation with the barb  10 . 
     FIG. 3  shows an embodiment where corresponding features have the same references as in  FIG. 1 . The plug  12  i.e. its head  13  is split in order to give the plug head a resiliency necessary to enter the slot  9  and engage behind the barbs  10  and  11 . 
     FIG. 4  shows a possible profile element  6 ′ in the form of a cylindrical body having a slot  9 ′ extending radial inwards and ending in a cavity  21  for receiving the undercut plug head (not shown). This profile element  6 ′ may preferably be in a plastic material. It has here an enlarged massive head  22  adapted to close the bore wherein the element  6 ′ is placed. 
   An elongated profile element  23  is shown in  FIG. 5 . This profile element  23  is adapted for cooperation with a number of plug members  24 , as shown in the figure and is fastened to a structural component  25  by means of screws (not shown). 
   Such elongated elements  23  may for inst. be used in the erection of a fence  26  or wall as shown in  FIG. 6 . A number of elongated elements  23  are by suitable means f.inst. screws (not shown) fastened to posts  27  (only one post shown). Planks  28  are connected to the profile elements  23  by means of fixing means according to the invention.  FIG. 6  shows a fixing means  29  as in  FIG. 1  whereas the other fixing means  30  is modified in that the plug  9 ″ is threaded and cooperates with a head nut  31 . 
   The person skilled in the art will appreciate that the plug and the profile element may have other suitable form and that the undercut engagement may be realised in other equivalent forms than here shown and described. There may be situations where the springy effect is not necessary, as f.inst. when using elements as in  FIG. 5  where the plugs may be inserted lengthwise in the profile elements. Both the profile element and the plug may have a certain resiliency, as caused by the material used or by the specific springy form of the two parts. 
     FIG. 7  shows an embodiment substantially as in  FIG. 1 . The two structural components  32  and  33  are connected by means of a plug member  34  having an undercut head  36  engaging the plate portions  37  and  38 . The plug member has an internal threaded bore  39  where a threaded element  40  is threaded. The diameter of the bore  39  is so large that the bore  39  penetrates the plug member wall behind the undercut head  36 . Thus, when threaded into the bore  39  the threaded element will push the plate portions out of engagement as disclosed in the right part of the  FIG. 7 , where the plate portion  38  is shown pushed out sideways. The plug member will then be free and can be pulled out. In  FIG. 7  the plug member  34  is tightened by means of a nut  35 . 
     FIGS. 8 and 9  show a modification of the element in  FIG. 4 . The element  6 ″ is as in  FIG. 4  but is given a flexibility in that a cut  41  is performed in the body thus giving the element a certain flexing capacity, corresponding to that of the flexible plate portions  7  and  8  in  FIG. 1 . 
   In certain cases there may be a need for securing or locking the retaining engagement and the  FIGS. 10-12  show possible locking members to be used, f.inst. as indicated with broken lines in  FIG. 1  where a locking member  42  as in  FIG. 10  is inserted in the bore  3 . The locking member will back the plate portions  7  and  8  as shown in  FIG. 1 . 
   Another possible locking member is that in  FIG. 11 . This locking member  43  has two pins  45 , 46  extending out from a plate or head  47  and may be inserted and used as shown in  FIG. 13 . 
     FIG. 12  shows a locking member  48  which may be used as shown in  FIG. 14 . 
     FIG. 13  shows an embodiment substantially as in  FIG. 1  but where the profile element  6  is made of thin flatsteel, the ends of the inwardly bent portions  7  and  8  being received in grooves  49 , 50  in the undercut head  9 . Additionally the retaining engagement is strengthened in that a locking member  45 , 46  is inserted.