Patent Publication Number: US-2021172467-A1

Title: Connecting element for connecting profile elements

Description:
The present invention relates to a connecting element for connecting at least two profile elements. The present invention relates further to an assembly group comprising a profile element and such a connecting element. 
     Such connecting elements are known from the prior art and disclosed, for example, in document DE 101 46 492 A1. The connecting element disclosed in that document consists of two toggle elements arranged at opposite ends of an intermediate piece. The toggle elements are designed to be inserted into receptions of profiles that are to be connected together. Connection of the profiles by means of the connecting element is carried out by first inserting the toggle elements into the receptions and rotating them. For rotating the connecting element, attachment surfaces in the form of a hexagon head for attachment of a spanner or the like are provided between the toggle elements. Rotationally fixed connection of the two profiles is effected in that, on rotation, the narrow sides of the toggle elements are clamped against the lateral delimiting walls of the groove-like receptions of the profiles to form protection against over-rotation. 
     It is an object of the present invention to further improve such a connecting element in particular in respect of its clamping action. Furthermore, it is a further object of the present invention to provide a connecting element which allows to form an assembly group with a profile element and to be connected as an assembly group, i.e. together with the profile element, to a further profile element. 
     These objects are achieved according to the invention by a connecting element having the features indicated in patent claim  1 . 
     Further embodiments are indicated in the dependent claims. 
     The connecting element for connecting at least two profile elements is rotatable about an axis of rotation in order to produce a clamping force. The connecting element has at least one first connecting portion and at least one second connecting portion, which are each configured to be received in one of the profile elements. The first connecting portion has at least one clamping face, wherein the at least one first clamping face is configured with a predetermined clamping contour. The second connecting portion has at least one second clamping face, wherein the first clamping face faces the second connecting portion and the second clamping face faces the first connecting portion. The first connecting portion and the second connecting portion are so configured that the profile elements connected by means of the connecting element extend obliquely relative to one another or crosswise. 
     The two connecting portions of the connecting element can each be inserted into a reception of a profile element. The clamping faces of the connecting portions can cooperate in such a manner that, by rotation of the connecting element about the axis of rotation, a clamping force is produced by the webs or projections which define the opening of the reception in the profile element. By means of the connecting element it is possible to connect two profile elements which, after connection by means of the connecting element, extend obliquely relative to one another, transversely relative to one another or crosswise. For producing a clamping force, the first clamping face, which extends at least in part obliquely relative to the axis of rotation, can engage one of the projections of the profile element which define the slot-like opening extending in the direction of the longitudinal axis. The first connecting portion and the second connecting portion can be formed on the connecting element offset relative to one another about the axis of rotation by a predetermined angle. This angle can be 90°, for example. The angle by which the first connecting portion and the second connecting portion are offset relative to one another about the axis of rotation can depend on the angle which the two profile elements, or the longitudinal axes of the profile elements, are to have relative to one another in the state in which they are connected via the at least one connecting element. The first connecting portion and the second connecting portion can also be in alignment, as seen in the direction of the axis of rotation. 
     The second connecting portion can be so configured that the second connecting portion can be received in a reception of one of the two profile elements via a press fit. Furthermore, the second connecting portion can be so configured that it can be pushed or inserted into the reception starting from an end face or end side of a profile element. The connecting element is displaced by means of the second connecting portion into a predefined position on the profile element. The connecting element can be positioned, for example, centrally in the reception of the profile element. The at least one connecting element and the profile element can form an assembly group which is fixedly connected together. The at least one connecting element can be connected to the profile element in a rotationally fixed manner. The connecting element can be permanently fixedly connected to the profile element. 
     The assembly group comprising the profile element and the pushed-in connecting element can be connected by means of the connecting element to a further profile element. To that end, the first connecting portion of the profile element is inserted into the reception of the profile element with which a connection is to be made. The assembly group can thereafter be rotated relative to that profile element about the axis of rotation of the connecting element. The amount of the relative rotation can be 90°, for example. The rotation of the connecting element can be initiated by the profile element with which the connecting element forms an assembly group. In this case, no additional tool is required to make a connection between two profile elements via the connecting element. It is sufficient to insert the first connecting portion of the connecting element into the reception of the profile element and to rotate the assembly group relative to that profile element. 
     On the second connecting portion there can be formed at least one projection with which the second connecting portion is supported on the reception of a profile element. It is also possible for multiple projections to be formed on the second connecting portion. By means of the projections, the second connecting portion can be supported on the walls of the groove-like reception of the profile element. For example, a projection can be formed on the upper side and a projection can be formed on each of the lateral faces of the second connecting portion. Each of these projections can be supported on a wall of the reception. For example, the projection on the upper side of the second connecting portion can be supported on the bottom face of the reception. The projections on the side faces of the second connecting portion can be supported on the lateral faces of the reception. 
     The at least one projection can be bent. The connecting element can be inserted in the direction of the longitudinal axis of the profile element. The at least one projection on the second connecting portion can be bent in the direction of the longitudinal axis of the profile element. As a result, the insertion or centering of the second connecting portion on the profile element can firstly be simplified. The further the second connecting portion is pushed into the reception and the further the projection is bent outwards, the greater the forces with which the connecting portion is braced in the reception of the profile element. For example, the projection on the upper side of the second connecting portion can be bent. The bend extends along the direction of insertion of the connecting element or of the second connecting portion into the reception of the profile element. As already mentioned, the second connecting portion is inserted or pushed into the reception of the profile element starting from an end face of the profile element. 
     The at least one first clamping face and the at least one second clamping face can form between them at least one clamping channel for clamping a portion of one of the profile elements. 
     The connecting portion can have at least one support face with which the second connecting portion can be supported at the reception of a profile element. The at least one support face can in particular rest against the webs or projections which define the opening of the reception. The second clamping face of the second connecting portion can extend substantially parallel to the at least one support face. Between the second clamping face and the at least one support face there can be provided a step, or a shoulder, which is formed by two guide faces. The guide faces can extend at an angle or substantially perpendicular to the second clamping face. The guide faces can further extend at an angle or substantially parallel to one another. The distance between the guide faces can be matched to the distance between the two projections which define the slot-like opening of the reception of the profile element. The webs can rest against the guide faces which connect the at least one support face to the at least one second clamping face. By means of the guide faces, the second connecting portion can be guided in the reception during insertion or pushing in. Furthermore, the guide faces can inter alia prevent the second connecting portion from being able to rotate relative to the profile element in the reception of the profile element. The second connecting portion can be held in its predetermined position and posture in the reception of the profile element by means of the distance between the guide faces and/or the dimensioning the second connecting portion. The second connecting portion can be held in its predetermined position and posture in the reception of the profile element by means of the guide faces and/or its dimensioning even when the connecting element forms an assembly group with a profile element and that assembly group, in order to produce a connection with a further profile element, is rotated relative to that profile element. 
     Between the first connecting portion and the second connecting portion there can be arranged at least one bearing portion. The at least one bearing portion can have at least one third clamping face and at least one fourth clamping face. The third clamping face can face the first clamping face of the first connecting portion. The fourth clamping face can face the second clamping face of the second connecting portion. The at least one first clamping face and the at least one third clamping face can define between them at least one clamping channel. Furthermore, the at least one second clamping face and the fourth clamping face can define between them at least one further clamping channel. The first connecting portion and the second connecting portion can be formed on the connecting element offset relative to one another by 90°, for example, about the axis of rotation. In particular, the at least one first clamping face and the at least one second clamping face can be formed on the connecting portions offset by 90° relative to one another about the axis of rotation. The first connecting portion and the second connecting portion can also be in alignment, as seen in the direction of the axis of rotation. The at least one first clamping face and the at least one second clamping face can likewise be in alignment, as seen in the direction of the axis of rotation. 
     The connecting element can have attachment faces at which a tool for rotating the connecting element can be attached. The bearing portion can be in plate form. The bearing portion can have a square, rectangular or polygonal basic shape. The third clamping face and the fourth clamping face can be provided on opposite sides of the at least one bearing portion. The first clamping face of the first connecting portion and the second clamping face of the second connecting portion can face one another and, owing to the arrangement of the bearing portion between the clamping faces of the first and of the second connecting portion, also the third and fourth clamping faces. 
     The connecting element can be inserted with its first connecting portion into a reception of a profile element. A second profile element is then fitted with its reception onto the second connecting portion of the connecting element. The connecting element can thereafter be rotated through 90°, for example, whereby a clamping action is produced by means of the clamping contour on the first and second clamping faces between the first clamping face, the third clamping face and one of the projections on the reception of the first profile element and between the second clamping face, the fourth clamping face and one of the projections on the reception of the second profile element. In other words, the profile elements and the connecting element are clamped together and thus connected together by the rotation of the connecting element. The profile elements then extend obliquely relative to one another or cross. The longitudinal axes of the profile elements can extend transversely or obliquely relative to one another, but may also cross. 
     The second clamping face of the second connecting portion can be configured with a predetermined clamping contour. The clamping contour of the second clamping face of the second connecting portion can correspond to the clamping contour of the first clamping face of the first connecting portion. The two clamping contours of the first clamping face and of the second clamping face may, however, also be different from one another. 
     The clamping contour of the at least one first clamping face of the first connecting portion and/or the clamping contour of the at least one second clamping face of the second connecting portion can have a bend or curve. The first and second clamping surfaces can be bent towards one another. The first clamping face can accordingly be curved in the direction of the second clamping face and the second clamping face can be curved in the direction of the first clamping face. Furthermore, the first and second clamping faces can also be curved in the direction of the third and fourth clamping faces on the at least one bearing portion. Owing to the curve of the clamping faces, a clamping force can be produced between the connecting element and the respective profile element by the rotation of the connecting element. 
     The clamping contour of the first clamping face and/or the clamping contour of the second clamping face can each be configured with an undercut. By means of the undercut, a relatively great clamping force can be produced. By means of the undercut, the connecting element can thus be prevented from becoming detached from one of the profile elements. 
     The connecting element can be produced from castable or injection moldable materials. The at least one connecting element can be produced, for example, from aluminum, zinc or fiber-reinforced plastics materials such as PE, PP, PC, POM, PET, PEEK or PA. For example, the at least one connecting element can be produced by an aluminum diecasting method or a zinc diecasting method. It is also conceivable that the connecting element is produced from several different materials. 
     The connecting element for connecting at least two profile elements can be so configured that the connecting element is rotatable about an axis of rotation in order to produce a clamping force, wherein the connecting element has at least one first connecting portion and at least one second connecting portion which are each configured to be received in one of the profile elements, wherein the first connecting portion has at least one first clamping face, wherein the at least one first clamping face is configured with a predetermined clamping contour, wherein the second connecting portion has at least one second clamping face, wherein the first clamping face faces the second connecting portion and the second clamping face faces the first connecting portion. 
     The present invention relates further to an assembly group having at least one profile element and at least one connecting element of the type described hereinbefore. The at least one connecting element is received with its second connecting portion in the reception of the at least one profile element via a press fit. The at least one connecting element of the assembly group can be inserted with the first connecting portion into a reception of a further profile element. Following insertion into the reception, the assembly group comprising the profile element and the connecting element can be rotated relative to the further profile element so that the first connecting portion can clamp the two profile elements together. 
    
    
     
       Exemplary embodiments will be described hereinbelow with reference to the accompanying figures, in which: 
         FIGS. 1 to 5  are different views of a connecting element according to a first embodiment; 
         FIG. 6  is a perspective view of a profile element and of a connecting element according to the first embodiment before connection to form an assembly group; 
         FIG. 7  is a perspective view of the assembly group formed by a profile element and the connecting element according to the first embodiment; 
         FIG. 8  is a perspective view of the assembly group according to  FIG. 7 , wherein the first connecting portion of the connecting element of the assembly group has been inserted into a reception of a further profile element; 
         FIG. 9  is a perspective view of the assembly group and of the profile element according to  FIG. 8 , wherein the assembly group has been rotated through 45° relative to the profile element; 
         FIG. 10  is a perspective view of the assembly group and of the profile element in the connected state, that is to say the assembly group has been rotated through about 90° relative to the profile element; 
         FIGS. 11 to 15  are different views of a connecting element according to a second embodiment; 
         FIG. 16  is a sectional view along cutting line XVI-XVI in  FIG. 14 ; 
         FIG. 17  is an enlarged view of detail XVII-XVII in  FIG. 15 ; 
         FIG. 18  is a sectional view along cutting line XVIII-XVIII in  FIG. 14 ; and 
         FIG. 19  is an enlarged view of detail XIX in  FIG. 14 ; and 
         FIGS. 20 and 21  are views of the mounting of the connecting element according to the second embodiment. 
     
    
    
       FIGS. 1 and 2  show perspective views of a connecting element  10  according to a first embodiment. 
     The connecting element  10  has a first connecting portion  12  and a second connecting portion  14 . The first connecting portion  12  has a head portion  16  and a column-like portion  18  which connects the head portion  16  to the second connecting portion  14 . On the head portion  16  there are formed the two first clamping faces  20  and  22 , which point in the direction of the second connecting portion  14 . The clamping faces  20  and  22  have a predetermined clamping contour. As can be seen in  FIG. 1 , the first clamping faces  20  and  22  have a clamping contour which has a bend or curve. An undercut with which the clamping contours of the clamping faces  20  and  22  are provided is also only adumbrated in  FIG. 1 . In this context, the expression “clamping faces” is to be understood as meaning faces which come into contact with at least one of the profile elements (not shown) that are to be connected by means of the connecting element  10 , or which rest against one of the profile elements. 
     The second connecting portion  14  has a second clamping face  24  which points in the direction of the first clamping faces  20 ,  22 . Adjoining the second clamping face  24  is a step or shoulder which forms the transition into support faces  26  and  28 . By means of the spacing faces  26 ,  28 , the second connecting portion  14  is able to be supported against the reception (not shown) of a profile element (not shown). The spacing faces  26 ,  28  are connected by means of guide faces  30  and  32  to the second clamping face  24 . The guide faces  32  and  34  extend substantially perpendicularly to the support faces  26 ,  28  and the second clamping face  24 . The guide faces  30 ,  32  can guide the insertion movement of the second connecting portion  14  into a reception, not shown, of a profile element (not shown) and prevent rotation of the second connecting portion  14  relative to the profile element (not shown). Adjoining the support faces  26  and  28  are two projections  34  and  36  which are formed on the lateral faces  38  and  40  of the second connecting portion  14 . Adjoining the lateral faces  38  and  40  is a top face  42  of the second connecting portion  14 , which connects the lateral faces  38  and  40  to one another. The top face  42  has a projection  44 . The projection  44  is provided with a bend, as is visible in  FIGS. 1 and 2 . The second connecting portion  14  further has a front face  46  and a rear face  48  which extend between the second clamping face  24 , the guide faces  28 ,  30 , the support faces  26 ,  28 , the lateral faces  38 ,  40  and the top face  42 . 
       FIG. 3  shows a front view of the connecting element  10 . In  FIG. 3 , the first connecting portion  12  and the second connecting portion  14  can be seen. The first connecting portion  12  has the head portion  16  and the column-like portion  18  which connects the first connecting portion  12  to the second connecting portion  14 . In particular, the portion  18  of the first connecting portion  12  is connected to the second clamping face  24  of the second connecting portion  14 . The portion  18  of the first connecting portion  12  is arranged centrally on the second clamping face  24 . The second clamping face  24  extends around the end of the portion  18 . On the head portion  16  there is formed the first clamping face  20 , which points in the direction of the second clamping face  24  on the second connecting portion  14 . The clamping face  20  has a predetermined clamping contour KK. As can be seen in  FIG. 3 , the clamping contour KK of the first clamping face  20  is in bent form. The clamping face  20  extends between the lateral faces  50  and  52  of the first connecting portion. Starting from the left lateral face  52  in  FIG. 3 , the clamping face  20  extends bent in the direction of the axis of rotation D, wherein the bend has its apex in the region of the axis of rotation D. After the apex, which is located in the region of the axis of rotation D in the view according to  FIG. 3 , the clamping face  20  falls with a slight bend in the direction of the right lateral face  50  in  FIG. 3  of the first connecting portion  12 . The starting point of the clamping face  20  on the lateral face  52  lies in the direction of the axis of rotation D beneath the end point of the clamping face  20  on the lateral face  50 . By means of the clamping contour KK of the clamping face  20 , a profile element (not shown) can be clamped between the first clamping face  20  and the second clamping face  24  opposite the first clamping face  20  by rotation about the axis of rotation D of the connecting element  10 . The second clamping face  24  according to this embodiment extends substantially perpendicularly to the axis of rotation D. 
       FIG. 4  is a side view of the connecting element  10 . The head portion  16  of the first connecting portion  12  has the two clamping faces  20  and  22 . The clamping faces  20  and  22  each have a predetermined clamping contour KK 1  and KK 2 . The clamping contours KK 1  and KK 2  are bent and have an undercut. The undercut of the clamping contours KK 1  and KK 2  is recognizable in that the edges  54  and  56 , which extend along the portion  18 , are located at least in part in the direction of the axis of rotation D beneath the outer edges  58  and  60  of the clamping faces  20  and  22 . The further the clamping faces  20  and  22  extend away from the axis of rotation D, the greater the extent of the head portion  16  in the direction of the axis of rotation. 
     The projection  44  is bent in form. The bend of the projection  44  extends in a direction transverse to the axis of rotation D. The apex of the bend of the projection  44  lies in the region of the axis of rotation D. 
     The first clamping face  20  and the clamping face  24  define between them a first clamping channel K 1 . The first clamping face  22  and the second clamping face  24  define between them a second clamping channel K 2 . The clamping faces  20  and  22  are opposite the clamping face  24 . In a direction transverse to the axis of rotation D, the clamping channels K 1  and K 2  are delimited by means of the wall faces  62  and  64  of the portion  18  of the first connecting portion  12 . Owing to the undercut and owing to the bend of the clamping faces  20  and  22  in the direction of the second clamping face  24 , the cross-section of the clamping channels K 1  and K 2  changes in a direction about the axis of rotation D. Owing to this cross-section of the clamping channels K 1  and K 2 , the clamping force increases the further the connecting element  10  is rotated relative to the profile element (not shown) which can be connected to the first connecting portion  12 . For example, the clamping contours KK 1  and KK 2 , or the cross-section of the clamping channels K 1  and K 2  resulting therefrom, can be so configured that the clamping force is greatest when the connecting element  10  has been rotated through about 90° about the axis of rotation D relative to the profile element (not shown) which is to be clamped to the first connecting portion  12 . 
       FIG. 5  is a plan view of the connecting element  10 . In  FIG. 5 , the top face  42  of the connecting element  10  is shown. The top face  42  has the projection  44 . On the lateral faces  40  and  42  of the second connecting portion  14  there are formed the projections  36  and  38 . The connecting portions  12  and  14  can be in alignment, as seen in the direction of the axis of rotation D (see also  FIGS. 3 and 4 ). 
       FIG. 6  is a perspective view of a profile element  100  and of the connecting element  10  according to the first embodiment. The profile element  100  and the connecting element  10  can be connected together in order to form an assembly group. In order to form an assembly group, the connecting element  10  is inserted with its second connecting portion  14  into a reception  102  of the profile element  100 . The profile element  100  has, in addition to the reception  102 , a further reception  104  on its upper side. The connecting element  10  is inserted or pushed into the reception  102  from the end side  106 . The connecting element  10  is inserted with its second connecting portion  14  in the direction of the longitudinal axis L of the profile element  100 . The insertion direction is again represented by the arrow PE in  FIG. 6 . It is, however, also possible to introduce the connecting element  10  into the reception  102  of the profile element  100  starting from the end side  108 . 
     In  FIG. 7 , the connecting element  10  has been pushed into the reception  102  of the profile element  100 . The connecting element  10  is positioned substantially centrally in the reception  102  of the profile element  100  in the direction of the longitudinal axis L. The reception  102  is rectangular in cross-section and has two webs or projections  110  and  112  which define a slot-like opening  114  extending in the direction of the longitudinal axis L. The second connecting portion  14  of the connecting element  10  is received in the reception  102  of the profile element  100  by a press fit. The profile element  100  and the connecting element  10  form an assembly group BG. The assembly group BG can be connected by means of the connecting portion  12  to a further profile element (not shown). The profile element  100  can be a support for the solar modules, for example. 
       FIG. 8  is a perspective view of the assembly group BG in the state in which it has been inserted but not yet fixedly connected to a further profile element  200 . The profile element  200  has a reception  202  into which the first connecting portion  12  of the connecting element  10  has been inserted. The profile element  100  of the assembly group BG lies with its lower side against the upper side of the reception  202  of the profile element  200 . The reception  202  of the profile element  200  has webs or projections  204 ,  206  which delimit a slot-like opening  208 . Through the opening  208 , the second connecting portion  12  of the connecting element  10  has been inserted into the reception  202 . 
     The second connecting portion  14  of the connecting element  10  is, as has already been described in connection with  FIG. 7 , received in the reception  102  of the profile element  100  via a press fit. The second connecting portion  14  is supported by means of the projections  34 ,  36  and  44  on the wall faces of the reception  102 . The support faces  26  and  28  lie against the projections  110  and  112  of the reception  102 . The guide faces  30 ,  32  lie against the mutually opposite delimiting faces  116 ,  118  of the projections  110 ,  112  which delimit the opening  114 . The region of the second connecting portion  14  between the guide faces  30 ,  32  is received between the delimiting faces  116 ,  118  on the projections  110 ,  112 . 
     In  FIG. 8 , the first connecting portion  12  has been inserted into the reception  202  of the profile element  200  but is not yet fixedly connected to the profile element  200 . Insertion into the reception  202  can take place from above through the opening  208  of the reception  202 . The connecting element  10 , and thus the assembly group BG, is not yet fixedly connected to the profile element  200  since the assembly group BG has not yet been rotated relative to the profile element  200 . In this state, the profile elements  100  and  200  still extend “parallel” to one another. 
       FIG. 9  is a perspective view in which the assembly group BG has been rotated relative to the profile element  200 . In  FIG. 9 , only the profile element  100  of the assembly group BG is visible. The profile element  100  extends obliquely relative to the profile element  100 . The longitudinal axis L 1  of the profile element  100  extends obliquely relative to the longitudinal axis L 2  of the profile element  200 . The profile element  100  has been rotated through about 45° relative to the profile element  200  in  FIG. 9 . 
     In  FIG. 10 , the assembly group BG is shown in the state in which it is fixed to the profile element  200 . Starting from the intermediate position of the assembly group BG shown in  FIG. 9 , the assembly group BG, that is to say the profile element  100  and the connecting element  10 , has been rotated further into the end position shown in  FIG. 10 . The assembly group has been rotated through 90° relative to the profile element  200 . In this state, the clamping faces  20 ,  22  and  24  (see  FIGS. 1 to 4 ) of the connecting element  100  lie against the projections  204  and  206  of the reception  202  of the profile element  200 . The clamping contours KK 1  and KK 2  (see  FIG. 4 ) of the clamping faces  20  and  22 , together with the clamping face  24 , produce a clamping action for holding the assembly group BG on the profile element  200 . In this state, the profile element  100  of the assembly group BG extends transversely to the profile element  200 . The longitudinal axis L 1  of the profile element  100  and the longitudinal axis L 2  of the profile element  200  extend crosswise. 
     A connecting element  10  according to a second embodiment will be described hereinbelow with reference to  FIGS. 11 to 21 . For features or components which are the same or have the same effect, the same reference numerals as in the first embodiment are used. In order to avoid repetition, the differences between the two embodiments will be described in detail hereinbelow. Components and features which have already been described in relation to the first embodiment will not be described in detail again. The description of these components and features also applies analogously to the second embodiment. 
       FIGS. 11 and 12  are perspective views of a connecting element  10  according to the second embodiment. The connecting element  10  according to the second embodiment has a first connecting portion  12 , a second connecting portion  14  and a bearing portion  66 . The bearing portion  66  is arranged between the first connecting portion  12  and the second connecting portion  14 . The first connecting portion  12  and the second connecting portion  14  are of substantially identical construction, wherein the second connecting portion  14  is arranged on the bearing portion  66  offset by 90° relative to the first connecting portion  12 . The remarks made in relation to the first connecting portion  12  according to the first embodiment thus apply analogously to the two connecting portions  12  and  14  according to the second embodiment. 
     The first connecting portion  12  has a head portion  16  and a column-like portion  18  which connects the first connecting portion  12  to the bearing portion  66 . On the head portion  16  there are formed first clamping faces  20  and  22 , which face a clamping face  68  on the bearing portion  66 . The clamping faces  20  and  22  have a predetermined clamping contour KK 1  and KK 2 . 
     The second connecting portion has a head portion  70  and a column-like portion  72  which connects the second connecting portion  14  to the bearing portion  66 . On the head portion  70  there are formed clamping faces  24  and  74 , which face a clamping face  76  on the bearing portion  66 . The clamping faces  24  and  74  are offset by 90° relative to the clamping faces  20  and  22  of the first connecting portion  12 . On the upper side of the head portion  70  of the second connecting portion there is visible a slot  78  which marks the upper side or the upper portion of the connecting element  10 . 
     The bearing portion  66  is in plate form according to this embodiment and has a square basic shape. The lateral faces  80  of the bearing portion  66  form attachment faces for the attachment of a tool for mounting the connecting element  10 . The attachment faces  80  can be so-called spanner flats to which a tool similar to a spanner can be attached. 
       FIG. 13  is a plan view of the connecting element  10 . In  FIG. 13 , the second connecting portion  14  and the bearing portion  66  are shown. The bearing portion  66  is square and plate-like in form. On the bearing portion  66  there are formed four attachment faces  80  to which a tool for rotating the connecting element  10  can be attached. On the upper side of the second connecting portion  14  there is shown the slot  78  which marks the upper side or the upper portion of the connecting element  10 . 
       FIGS. 14 and 15  are views of the connecting element  10  from different viewing directions. For reasons of clarity, not all the features have been provided with reference numerals in the two figures. In connection with the first connecting portion  12 , reference is also made, in order to avoid repetition, to the detailed description of the first connecting portion  12  in connection with the first embodiment described hereinbefore. 
     The first connecting portion  12  has a head portion  16  and a column-like portion  18  which connects the first connecting portion  12  to the bearing portion  66 . The first connecting portion  12  has on its head portion  16  two clamping faces  20  and  22  which have a predetermined clamping contour KK 1  and KK 2  (see  FIGS. 4 and 14 ). The clamping faces  20  and  22  face a clamping face  68  on the bearing portion  66 . The clamping face  68  extends substantially perpendicularly to the axis of rotation D. The clamping faces  20  and  22 , together with the clamping face  68 , define two clamping channels K 1  and K 2  which are associated with the first clamping portion  12 . The clamping channels K 1  and K 2  are further delimited by the wall portions  62  and  64  on the portion  18 , which delimit the clamping channels K 1  and K 2  in a direction transverse to the axis of rotation D. 
     The second connecting portion  14  has a head portion  70  and a column-like portion  72 . The column-like portion  72  connects the head portion  70  to the bearing portion  66 . On the head portion  70  there are formed two clamping faces  24  and  74 . The clamping faces  24  and  74  have predetermined clamping contours KK 3  and KK 4  (see  FIGS. 11 and 12 ). The clamping faces  24  and  74  face the clamping face  76  on the bearing portion  66 . The clamping face  76  extends substantially perpendicularly to the axis of rotation D. The clamping faces  24  and  74 , together with the clamping face  76  on the bearing portion  66 , define two clamping channels K 3  and K 4 . The clamping channels K 3  and K 4  are further delimited by the wall portions  82  and  84  on the portion  72 , which delimit the clamping channels K 3  and K 4  in a direction transverse to the axis of rotation D. 
       FIG. 16  is a sectional view along cutting line XVI-XVI in  FIG. 14 . In  FIG. 16 , the head portion  70  and the column-like portion  72  are shown. On the head portion  70  there are formed the clamping faces  24  and  74 . The clamping faces  24  and  74  each have a predetermined clamping contour KK 3  and KK 4 . The clamping faces  24  and  74  extend, starting from the lateral wall faces  82  and  84  of the portion  72 , at an angle to those wall faces  82  and  84 . The wall faces  82  and  84  extend between the lateral faces  86  and  88  of the first connecting portion  14 . The wall faces  82  and  84  have a straight portion and a bent portion. Starting from one of the lateral faces  86  and  88 , the wall faces  82  and  84  extend with their straight portion first substantially at a right angle to one of those lateral faces  86  and  88 . With the bent portion, the wall faces  82  and  84  then merge into the respective other lateral face  86  and  88  of the first connecting portion  14 . 
       FIG. 17  is an enlarged view of detail XVII in  FIG. 15 . The clamping faces  74  and  76 , together with the wall face  82  of the portion  72 , define the clamping channel K 4 . The clamping face  74  has a predetermined clamping contour KK 4  which is provided with an undercut. The undercut is formed by an angle α between the clamping face  74  and the wall face  82 , which extends parallel to the axis of rotation D (see  FIG. 15 ). The angle α can be between 45° and 85°. For example, the angle α can be 75°. 
       FIG. 18  is a sectional view along cutting line XVIII-XVIII in  FIG. 14 . In  FIG. 18 , the first connecting portion  12  is shown. On the head portion  16  of the first connecting portion  12  there are formed the clamping faces  20  and  22 . The clamping faces  20  and  22  each have a predetermined clamping contour KK 1  and KK 2 . The clamping faces  20  and  22  extend starting from the lateral wall faces  62  and  64  of the portion  18 , that is to say the clamping faces  20  and  22  do not surround the column-like portion  18  completely. The wall faces  62  and  64  extend between the lateral faces  52  and  54  of the first connecting portion  12  at an angle to those wall faces  50  and  52 . The wall faces  62  and  64  have a straight portion and a bent portion. Starting from one of the lateral faces  50 ,  52 , the wall faces  62  and  64  extend with their straight portion first substantially at a right angle to that lateral face  50  and  52 . With the bent portion, the wall faces  62  and  64  then merge into the respective other lateral face  50  and  52  of the first connecting portion  12 . 
       FIG. 19  is an enlarged view of detail XIX in  FIG. 14 . The clamping faces  20  and  68 , together with the wall portion  62 , define a clamping channel K 1 . The cross-section of the clamping channel K 1  changes in a direction about the axis of rotation D. In particular, the cross-section of the clamping channel K 1  becomes smaller the further the clamping face  20  extends away from the axis of rotation D (see  FIG. 14 ). The clamping contour KK 1  of the clamping face  20  has an undercut. The undercut is formed by an angle β between the clamping face  20  and the wall face  62 , which extends parallel to the axis of rotation D (see  FIG. 15 ). The angle β can be between 45° and 85°. For example, the angle β can be 77°. 
       FIG. 20  is a perspective view of the connecting element  10  according to the second embodiment in the state in which it has been inserted in a profile element  100 . By means of the connecting element  10 , the two profile elements  100 ,  200  are to be connected. For this purpose, the connecting element  10  has been inserted with its first connecting portion  12  (see  FIGS. 14 and 15 ) into the reception  102  of the profile element  100 . In order to be able to connect the two profile elements  100  and  200  together, the connecting element  10  must be rotated relative to the two profile elements  100 ,  200 . Rotation takes place by means of the spanner  300  shown in  FIG. 20 . The spanner  300  has a spanner reception  302  in which the plate-like bearing portion  66  can be received. The spanner can be attached by its spanner reception  302  to the lateral attachment faces  80  of the bearing portion  66  (not shown). The connecting element  10  lies with its bearing portion  66  against the profile element  100  and the connecting portion  12  is received in the reception  102 . Although the connecting element  10  is received with its first connecting portion  12  in the reception  102 , it is not yet clamped to the profile element  100 . For this purpose, the connecting element  10  must be rotated relative to the two profile elements  100 ,  200  after the profile element  200  has been fitted to the second connecting portion  14  of the connecting element  10 . 
     In  FIG. 21 , the profile elements  100 ,  200  have been connected by means of the connecting element  10 . For this purpose, the connecting element  10  (see  FIG. 20 ) was rotated through 90° relative to the profile elements  100 ,  200  by means of the spanner  300 . That rotation has already taken place in  FIG. 21  is made clear in that the spanner  300  is lying with its stop  304  against the profile element  200 . The contact of the stop  304  with the profile element  200  makes it clear that the amount of rotation of the connecting element  10  necessary to connect the two profile elements  100 ,  200  has been performed. 
     The bearing portion  66  has a predetermined thickness in the direction of the axis of rotation D (see  FIGS. 14 and 15 ). The thickness of the bearing portion  66  allows the spanner  300  to be attached and removed from the region between the two profile elements  100 ,  200  even when the two profile elements  100 ,  200  are connected together, as is shown in  FIG. 21 . The thickness of the spanner  300  is accordingly matched to the thickness of the bearing portion  66 . The thickness of spanner  300  can be equal to or slightly smaller than the thickness of the bearing portion  66 .