Abstract:
An assembly of two profiled elements that each have a medial longitudinal edge and two longitudinal edges which are joined together by their medial edge and are kept movable apart from one another through a predefined limited travel. A cylindrical orifice passes perpendicularly through the medial longitudinal edge and a cylindrical element having dimensions that match the cylindrical orifice butts against the medial longitudinal edge such that the spacing of the medial edges causes the longitudinal edges to butt against the inner wall of the tubular element. A further embodiment is a connection kit for tubular elements and a tubular structure joined together by way of connection devices. The connection produced is either reversible or permanent.

Description:
[0001]    This invention relates to the field of tubular structures, both permanent and disconnectable, such as scaffolding, panel frames, frames for office furniture or various stands. More particularly, the invention relates to an internal connection device for tubular elements used, for example, in the above-mentioned context. 
     
    
     STATE OF THE ART/OUTLINE OF THE PROBLEM 
       [0002]    The user, such as the installer of various tubular structures, already has a large number of connection systems. Tubes are usually assembled by linear connection (coaxial connection) or by means of angled pieces (planar connection) or corner pieces (three-dimensional connection); welding is not considered here since it is practically irreversible. 
         [0003]    Assembly by the connection of tubular elements can be achieved by means of external connection devices such as flanges or rings or clips for example. A combination of male/female type screw, spring or ball connections, for example, is used, which therefore requires special machining of each of the ends to be connected. If the desired connection must be reversible, the separation of male/female type tubular elements is often awkward and a source of wear, breakage or distortion. 
         [0004]    The assembly of tubular elements internally derives from the above-mentioned male/female concept: it is often required for aesthetic reasons (office furniture or industrial furniture for example) but also for safety reasons (scaffolding for example) and so any potentially dangerous roughness must be eliminated. 
         [0005]    The invention proposes an internal connection device for tubular elements that is particularly simple and safe to use: it comprises a small number of constituent parts, the latter also being easy to make and available in a very wide range of variations (dimensions, material, shape, configuration, etc.). The invention thus enables the most complex assemblies to be created easily, while taking into account all of the mechanical constraints encountered in this context. 
       SUMMARY OF THE INVENTION 
       [0006]    The first object of the invention is an assembly of two profiled elements each comprising a medial edge and two longitudinal edges, the profiled elements being joined together by their respective medial edge, and the medial edges being kept movably spaced apart from one another along a limited travel; at least one cylindrical orifice passing perpendicularly through one of the medial edges, and one cylindrical element having dimensions that match the cylindrical orifice and abutting against the opposite medial edge so that the space between said medial edges causes the longitudinal edges of said profiled elements to abut against the internal wall of the tubular element. 
         [0007]    The invention also relates to a connection kit for tubular elements as well as a reversible or permanent tubular structure assembled by means of connection devices according to the invention. The invention is defined by claims  1  to  15 . 
     
    
     
       DRAWINGS 
         [0008]      FIG. 1  is a cross-sectional view of a connection device engaged in a cylindrical-section tubular element; 
           [0009]      FIG. 2  is a perspective view of the device in  FIG. 1  engaged only partly in the corresponding tubular element; 
           [0010]      FIG. 3  is a perspective view of the device in  FIG. 1  showing two cylindrical tubular elements connected by means of the device according to the invention; 
           [0011]      FIG. 4  is a cross-sectional view of the connection device engaged in a square-section tubular element; 
           [0012]      FIG. 5  is a perspective view of the device in  FIG. 4  only partially engaged in the corresponding tubular element; 
           [0013]      FIG. 6  is a cross-sectional view of the connection device engaged in a hexagonal-section tubular element; 
           [0014]      FIG. 7  is a perspective view of the device in  FIG. 6  only partially engaged in the corresponding tubular element; 
           [0015]      FIG. 8  shows the fitting of a compressible friction element before engaging the connection device in the corresponding tubular element; 
           [0016]      FIG. 9  shows the fitting of a compressible friction element after engaging the connection device in the corresponding tubular element. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0017]    The first object of the invention is defined as a connection device  1  for tubular elements  10   a,    10   a ′,  10   b,    10   c,  etc. comprising:
       an assembly of two profiled elements  2   a  and  2   b  each comprising one medial edge  3   a,    3   b  and two longitudinal edges  4   a,    4   b  respectively  5   a,    5   b;      said first and second profiled elements  2   a,    2   b  being joined together by their respective medial edge  3   a,    3   b  and being kept movably spaced apart from one another along a limited travel C;   the first profiled element  2   a  comprising at least one cylindrical orifice  6  passing perpendicularly through said medial longitudinal edge  3   a;          
 
         [0021]    at least one cylindrical element  7 , having dimensions that match the cylindrical orifice  6  and abutting against the medial edge  3   b  of the second profiled element  2   b;  and in which the portion of cylindrical element  7  protruding from the medial edge  3   a  of the first profiled element  2   a  and abutting on the medial edge  3   b  of the second profiled element  2   b  defines a spatial distance between said first and second profiled elements  2   a,    2   b  so that the longitudinal edges  4   a,    5   a,  respectively  4   b,    5   b,  abut against the internal wall  8  of the tubular element  10   a,    10   a ′,  10   b,    10   c,  etc. 
         [0022]    Reading the above reveals that one of the special features of the device of the invention consists in creating the connection of the tubular elements  10   a,    10   a ′,  10   b,    10   c,  etc. from the inside or, in other words, internally, the space between the profiled elements  2   a  and  2   b  being adjustable so that the pressure or friction required for the optimum fixing of the elements thus connected is exerted only on the internal wall  8  of said tubular elements  10   a,    10   a ′,  10   b,    10   c,  etc. Such a connection has the advantage of leaving practically, if not absolutely, no roughness whatsoever, protruding beyond the external surface of said tubular elements. 
         [0023]    Profiled element  2   a,  respectively  2   b,  can stand for an angled (angular), curved (e.g. parabolic) or semi-cylindrical profiled element. These configurations can be achieved by means of conventional techniques from a chosen material, such as by stamping a metal sheet such as a sheet of steel, stainless steel, aluminum or any other metal having the required mechanical properties: the extrusion of non-metallic composite materials such as polymers, for example, is also possible depending on the cases envisaged (mechanical stresses or weight of the assembly to be created). 
         [0024]    Each of the profiled elements  2   a  and  2   b  is characterized by a medial edge or tangent  3   a , respectively  3   b,  and two longitudinal edges or borders  4   a  and  5   a,  respectively  4   b  and  5   b,  by its length, by the height H of each of the lateral portions concerned and more particularly by the internal angle opening from the medial edge outwards (the internal angle of element  2   b  is shown as a in the Figures, whereas the internal angle of element  2   a  is not referenced). 
         [0025]    The dimensions of the portions described above can vary from one element to the other; for example, depending on the configuration chosen, the internal angle of element  2   a  is identical to the internal angle a of element  2   b  or different therefrom. According to the invention, angle a is usually between 30 and 150°, more particularly between 60 and 120°, an angle a of 90° representing one of the preferred variations proposed in the context of the invention. 
         [0026]    In the case of angled profiled elements, the notion of angle a is obvious as is the term “edge”. The notion of angle is also understood by extension to convex or semi-cylindrical curved profiled elements; in this case, the term “tangent” is more appropriate than “medial edge”. 
         [0027]    Similarly, the length of each of the medial edges  3   a  and  3   b  or that of the longitudinal edges  4   a,    5   a,    4   b,    5   b  is identical or varies in pairs or even individually; these variations in length have no determining effect on the efficiency of the connection made; a person skilled in the art is capable of choosing what is appropriate for each situation. 
         [0028]    The height H of each of the longitudinal edges  4   a,    5   a,    4   b  and  5   b  can also vary regardless of each of the portions (flanks, flanges or sides) considered and the lateral branches of each element  2   a  and  2   b  can vary in height in pairs. These configurations are found for example when assembling multi-angle tubular elements that are square, rectangular, diamond-shaped, trapezoidal, hexagonal or even octagonal in section for example; said section can even be circular, oval or elliptical for example. Such tubular elements are in fact those available on the market. 
         [0029]    The configurations in which the height H referred to above is identical for each of the side portions of  2   a  as well as  2   b  and in which the internal angles of elements  2   a  and  2   b  are also identical are shown in particular in  FIGS. 1 to 7 . Seen in cross-section, elements  2   a  and  2   b  are therefore identical, their assembly is symmetrical both before and after connection of the tubular elements  10   a  and  10   a ′; or  10   b  or  10   c,  and the distribution of the stresses against the internal wall  8  of said tubular elements is also symmetrical. This represents by far the most favourable configuration from a mechanical point of view. 
         [0030]    According to the invention, the medial edge  3   a  of the element  2   a  comprises at least one cylindrical orifice  6  passing perpendicularly through it and arranged in the center of or elsewhere on said medial edge; at least one cylindrical element  7  has dimensions that match the cylindrical orifice  6 , i.e. in diameter and length, in order to abut at the appropriate moment against the longitudinal medial edge  3   b  of the element  2   b,  so as to space the elements  2   a  and  2   b  apart from one another. The cylindrical element  7  can be a cylindrical element such as a pin, a dowel or, preferably, a threaded cylindrical element such as a screw or a bolt, in particular a slotted-head screw, a cross-head screw, socket-head cap screw, countersunk or otherwise; clearly, the cylindrical orifice  6  is then threaded. It is for a person skilled in the art to choose the most suitable tool. 
         [0031]    Depending on the desired configuration or assembly or even depending on the mechanical stresses to be controlled, element  2   a  of the assembly  1  can comprise several orifices  6  arranged along the edge  3   a  at regular or irregular intervals. 
         [0032]    An orifice  11  is formed in the wall of at least one of the two tubular elements that are to be fitted by means of the connection device of the invention. The orifice  11  is made near the end (terminal portion) of the tubular element. The orifice  11  is dimensioned so as to enable the operation of the tool  9  acting upon the element  7 , a screw  7  for example ( FIG. 3 ); in this latter case a conventional screwdriver, a Phillips screwdriver or a hexagonal-section key or a so-called “Allen” key is used. The orifice  11  can be a single circular perforation made in the required place or a longitudinal opening  11  enabling the fine adjustment of the relative position of the assembly  1  and the corresponding tubular element. 
         [0033]    According to the invention, the profiled elements  2   a  and  2   b  are joined together by at least one of their respective ends by means of a connecting part  12  configured so as to allow a limited travel C defining the maximum distance that the medial edges  3   a  and  3   b  are apart. This connecting part can be a ring, a pin, a bolt with its nut or a rivet for example, any part that, passing through the medial edge  3   a  and  3   b,  is then dimensioned so as to limit the travel C. In the case of a bolt and its nut, the latter can be secured at a given point; in the case of a rivet, the matter is easily resolved by upsetting the head and tail. In the simplest configuration, elements  2   a  and  2   b  are free to rotate flat without restriction; when the elements  2   a  and  2   b  are joined a both ends of the medial edges  3   a  and  3   b,  only the controlled spacing of the latter is possible. 
         [0034]    The maximum spacing C referred to above is relative and will vary depending on the dimension (e.g. diameter) of the tubular elements to be connected and on the dimensions chosen for elements  2   a  and  2   b.  The spacing C is usually only slightly greater than the distance required to immobilise the assembly  1  within the tubular element  10   a,    10   a ′,  10   b,    10   c,  etc., in other words, so that the elements  2   a  and  2   b  lie flat against the wall  8  under the effect of the spacing between the medial edges  3   a  and  3   b.  This space is in the order of a mm, however, and it is for the person skilled in the art to choose the most suitable configuration. 
         [0035]    The device also comprises, as an option, a compressible resilient element  13  with a maximum height (or diameter) H1 greater than the height H2 of a “triangle” whose apex coincides with the medial edge  3   a  of the element  2   a  and whose base is defined by the internal wall  8  of the tubular element. The resilient element is intended to be inserted in the internal angle of the profiled element  2   a.    
         [0036]    In an equivalent manner, the compressible element  13  can be defined by its maximum height (or its diameter) H1 greater than the height H2 of a “triangle” whose apex coincides with the medial edge  3   b  of the element  2   b  and whose base is defined by the internal wall  8  of the tubular element; the resilient element then being intended to be inserted in the angle a of the profiled element  2   b.  This configuration is shown in  FIGS. 8 and 9 . 
         [0037]    The element  13  is made of any resilient compressible material such as wood, cork, leather, rubber, a resilient polymer foam or a sufficiently resilient polymer. This element can also be hollow ( FIGS. 8 and 9 ) or solid. It serves as a brake, in other words a means of friction, when introducing then fitting or adjusting the assembly  1  in the terminal portion of the corresponding tubular element. 
         [0038]    The assembly of two tubular elements  10   a  and  10   a ′, by means of the device of the invention, is briefly described below by way of example; it comprises the following steps:
       a) inserting an assembly  1 , comprising the first and second profiled elements  2   a  and  2   b,  into a terminal portion of a first tubular element  10   a,  the latter being provided with an orifice  11  located at a predetermined distance from the corresponding end of said tube  10   a;      b) moving said assembly  1  forwards along a predetermined length so as to position the first profiled element  2   a,  comprising its threaded cylindrical orifice  6  and the threaded cylindrical element  7 , in order to align it with the axis of the orifice  11  of the terminal portion of the tubular element  10   a;      c) by doing this, the element  13  is gradually compressed as it advances into the above-mentioned terminal portion;   d) inserting the portion of the assembly  1  extending beyond the end of the first tubular element  10   a  into the terminal portion of a second tubular element  10   a ′, the latter possibly being provided with an orifice for the tool  9 ; and   e) actuating the threaded cylindrical element  7 , through the orifice  11  of the terminal portion of the tube  10   a,  until it abuts on the medial edge  3   b  of the second profiled element  2   b,  thus resulting in the spatial distancing of the medial edges  3   a  and  3   b , respectively the spatial distancing of the longitudinal edges  4   a,    5   a  and  4   b,    5   b  which thus abut against the internal wall  8  of the terminal portions of the tubular elements  10   a  and  10   a′.  
 
Such an assembly is both permanent and reversible. If the tubular elements  10   a  and  10   a ′ previously connected as described above are required to be separated, simply perform the procedure in the reverse order.
       
 
         [0044]    The connection kits comprising the device according to the invention, like the various assemblies of tubular structures that can thus be created, will not however be described below as their variations are too numerous.