Abstract:
A double-T stud with ring flanges at each end, for joining onto a workpiece surface. The stud including a joining portion and a head portion located at opposite ends of a shank. The head and joining portions formed as identical annular flanges with diameters greater than the shank portion. The stud is axially symmetrically in relation to a plane extending transverse to the shank.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from German Patent Application No. 10 2009 012 783.6, filed on Mar. 13, 2009, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a stud according to the preamble of Claim  1 , and to a fastening arrangement, comprising a workpiece, onto the surface of which a stud is joined, and comprising a clip, by means of which an object is fixed onto the workpiece. 
         [0003]    In particular, the present invention relates to such a joining stud and to a fastening arrangement that are designed to fix a substantially flat object, such as an underbody facing, onto a workpiece, such as a motor-vehicle body portion. The work-piece may be, for example, a sheet-metal material or another thin material. 
         [0004]    For the purpose of fastening objects to workpieces, there is known the practice of joining studs onto workpiece surfaces, in particular by welding or by adhesive-bonded joints. A clip, which is usually made of plastic, is fixed to such a stud. The clip serves to fix the object relative to the workpiece. 
       BRIEF SUMMARY OF THE INVENTION  
       [0005]    It is the object of the invention to specify an improved stud and an improved fastening arrangement for the above mentioned purposes. 
         [0006]    The above object is achieved by a stud according to Claim  1  and by a fastening arrangement according to Claim  8 . 
         [0007]    The stud according to the invention has, on the one hand, a joining portion that is provided at one end of the shank portion and realized as an annular flange. Such annular-flange studs are known in principle. Such studs are suitable, in particular, for joining onto workpieces of a relatively small material thickness (for example, &lt;1 mm or the like). A greater projected area can thereby be achieved, such that the joint can have a relatively high strength despite the small material thickness of the workpiece. Further, a head portion is provided at the other end of the shank portion. Owing to the head portion, which has a greater diameter than the shank portion, it is possible to fix clips onto the stud, in that these clips are not pressed onto the stud in axial direction but are pushed laterally onto the stud, the clip engaging the head portion axially. A fastening arrangement of low height can thereby be realized. Advantageously, the required mounting space above the stud is likewise smaller. 
         [0008]    Consequently, in the case of the fastening arrangement according to the invention, a clip is pushed onto the head portion in a transverse direction relative to the shank portion, in order to fix the object onto the workpiece. 
         [0009]    The object is thus achieved in full. 
         [0010]    The head portion may be realized as a solid portion, but is preferably realized as an annular flange. The head portion can thus be similar in form to the flange portion, this providing advantages in the automatic supplying of the stud to a joining tool. 
         [0011]    It is particularly preferred if the head portion has the same diameter as the joining portion. The stud can thus be supplied without difficulty to a joining tool, for example by means of pneumatic supply lines. 
         [0012]    In particular, it is preferred if the stud is realized symmetrically in relation to a plane extending transversely relative to the shank portion. 
         [0013]    It is particularly advantageous in this case that it is immaterial whether the stud is inserted into a joining tool with the head portion or the joining portion foremost, since the joining portion and the head portion are of identical design, and both are suitable as both joining portion and head portion. 
         [0014]    Further, it is advantageous if the stud is realized as a single piece. The stud can thus be produced inexpensively. 
         [0015]    The stud in this case can be made of metal or of plastic. In the case of the metal stud, the latter is preferably joined to a metal workpiece by welding (so-termed “stud welding”). In the case of a plastic stud, the latter can be adhesive-bonded onto a workpiece surface of any material. If the workpiece is likewise made of plastic, it is possible for the plastic stud to be joined to the workpiece by thermal welding. 
         [0016]    In the case of the fastening arrangement according to the invention, it is advantageous if the clip has a clamping portion, which is clamped between the head portion and the joining portion of the stud. In the case of this variant, the clip is clamped onto the stud, not between the head portion and the workpiece, but between the head portion and the joining portion. The distance between the head portion and the joining portion can be realized with a significantly lesser tolerance (i.e., with greater dimensional exactness), such that particularly secure fixing of the clip to the stud is possible. 
         [0017]    According to a further preferred embodiment, the object is fixed between a fastening portion of the clip and the surface of the workpiece. 
         [0018]    In this case, the object is aligned, in particular, so as to bear flatly on the workpiece, and is held on the workpiece from above by means of the clip. 
         [0019]    It is particularly preferred in this case if the fastening portion has at least one fastening arm, which extends radially outwards from the clamping portion. 
         [0020]    As a result, the flat object can be fixed with a relatively large projected area, and therefore securely, onto the workpiece. 
         [0021]    Further, it is advantageous in this case if at least two fastening arms are connected to one another at their distal ends to form a pressure portion. 
         [0022]    In the case of this embodiment, the pressure area acting upon the object can be enlarged. The pressure portion in this case can extend substantially along a circular form that is aligned concentrically relative to the stud and that is at least twice the distance from a longitudinal axis of the stud than the diameter of the head portion. 
         [0023]    Owing to the enlarged pressure area, a secure joint can be achieved, particularly in the case of elastically or plastically yielding materials of the object, without excessively high localized forces being exerted upon the object. 
         [0024]    It is understood that the abovementioned features and those to be explained in the following can be applied, not only in the respectively specified combination, but also in other combinations or singly, without departure from the scope of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING  
         [0025]    Exemplary embodiments of the invention are represented in the drawing and explained more fully in the following description, wherein: 
           [0026]      FIG. 1  shows a longitudinal section through a first embodiment of a stud according to the invention; 
           [0027]      FIG. 2  shows a perspective view of a fastening arrangement according to the invention, wherein a stud is joined onto a workpiece surface and an object (represented here, schematically, in the form of a circular disc, but usually extending over a greater area) is laid onto the workpiece surface; in this case, the object has a recess, through which the stud projects relative to the upper face of the object; 
           [0028]      FIG. 3  shows the fastening arrangement of  FIG. 2 , a clip having been pushed laterally onto the stud, as a result of which the object is fixed onto the work-piece; 
           [0029]      FIG. 4  shows a sectional view through the fastening arrangement of  FIG. 3 ; 
           [0030]      FIG. 5  shows an oblique top view of an alternative embodiment of a stud according to the invention; and 
           [0031]      FIG. 6  shows an oblique bottom view of a representation of the stud of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0032]    With reference to  FIGS. 1-4 , the stud  10  according to the invention has, on the one hand, a joining portion  18  that is provided at one end of the shank portion  12 . Joining portion  18  is formed as an annular flange having a diameter  22  and defining a recess  20 . Further, a head portion  24  is provided at the other end of the shank portion  12 . Owing to the head portion  24 , which has a greater diameter than the shank portion diameter  14 , it is possible to fix a clip  40  onto the stud  10 . Clip  40  is not pressed onto the stud  10  in the axial direction but, rather it is pushed laterally onto the stud, the clip engaging the head portion  24 . A fastening arrangement of low height can thereby be realized. Advantageously, the required mounting space above the stud is likewise smaller. 
         [0033]    Consequently, in the case of the fastening arrangement  30  according to the invention, a clip  40  is pushed onto the head portion  24  in a transverse (radial) direction  42  relative to the shank portion, in order to fix an object  34  onto the workpiece  32 . 
         [0034]    The head portion  24  may be realized as a solid portion, but is preferably realized as an annular flange with a recess  26 . The head portion  24  can thus be similar in form to the joining portion  18 , which symmetry is an advantage in the automatic supplying of the stud to a joining tool. 
         [0035]    It is particularly preferred if the head portion  24  has the same diameter  22  as the joining portion  18 . The stud  10  can thus be supplied without difficulty to a joining tool, for example by means of pneumatic supply lines. 
         [0036]    In particular, it is preferred if the stud  10  is realized symmetrically in relation to a plane  28  extending transversely relative to the shank portion  12 . 
         [0037]    It is particularly advantageous in this case that it is immaterial whether the stud  10  is inserted into a joining tool with the head portion  24  or the joining portion  18  foremost, since the joining portion and the head portion are of identical design, and both are suitable as both joining portion and head portion. 
         [0038]    Further, it is advantageous if the stud  10  is realized as a single piece. The stud can thus be produced inexpensively. 
         [0039]    The stud  10  in this case can be made of metal or of plastic. In the case of the metal stud  10 , the latter is preferably joined to a metal workpiece  32  by welding (so-termed “stud welding”). In the case of a plastic stud  10 , the latter can be adhesive-bonded onto a workpiece surface  33  of any material. If the workpiece  32  is likewise made of plastic, it is possible for the plastic stud  10  to be joined to the work-piece by thermal welding. 
         [0040]      FIG. 2  shows a perspective view of a fastening arrangement  30  according to the invention, wherein stud  10  is joined onto workpiece surface  33  and an object  34  (represented here, schematically, in the form of a circular disc  34 , but usually extending over a greater area) is laid onto the workpiece surface  33 . In this case, the object  34  has a recess  36 , through which the stud  10  projects relative to the upper face of the object; 
         [0041]      FIG. 3  shows the fastening arrangement of  FIG. 2 , with a clip  40  having been pushed laterally  42  onto the stud  10 , as a result of which the object  34  is fixed onto the workpiece  32 . 
         [0042]    In the case of the fastening arrangement  30  according to the invention in  FIGS. 3 and 4 , it is advantageous if the clip  40  has a clamping portion  44 , which is clamped between the head portion  24  and the joining portion  18  of the stud. In the case of this variant, the clip  40  is clamped onto the stud  10  between the head portion  24  and the joining portion  18 , not between the head portion  24  and the workpiece  32 . The distance between the head portion  24  and the joining portion  18  can be realized with greater dimensional exactness, such that particularly secure fixing of the clip  40  to the stud  10  is possible. 
         [0043]    According to a further preferred embodiment, the object  34  is fixed between a fastening portion  46  of the clip  40  and the surface  33  of the workpiece  32 . 
         [0044]    In this case, the object  34  is aligned, in particular, so as to bear flatly on the workpiece  32 , and is held on the workpiece  32  from above by means of the clip  40 . 
         [0045]    It is particularly preferred in this case if the fastening portion  46  has at least one fastening arm  48 , which extends radially outwards from the clamping portion  44 . As a result, the flat object  34  can be fixed with a relatively large projected area, and therefore securely, onto the workpiece  33 . 
         [0046]    Further, it is advantageous in this case if at least two fastening arms  48  are connected to one another at their distal ends to form a pressure portion  50 . In the case of this embodiment, the pressure area acting upon the object  34  can be enlarged. The pressure portion in this case can extend substantially along a circular form that is aligned concentrically relative to the stud  10  and that is at least twice the distance from a longitudinal axis  16  of the stud than the diameter  22  of the head portion  24 . 
         [0047]    Owing to the enlarged pressure area, a secure joint can be achieved, particularly in the case of elastically or plastically yielding materials of the object, without excessively high localized forces being exerted upon the object. 
         [0048]      FIG. 5  shows an oblique top view of an alternative embodiment of a stud according to the invention; and  FIG. 6  shows an oblique bottom view of a representation of the stud of  FIG. 5 . The stud  10 ′ of  FIG. 5  differs from the stud  10  of  FIG. 1  in the shape and geometry of its head portion  24 ′, shaft portion  12 ′ and joining portion  18 ′. The head portion  24 ′ might have the same diameter as the head portion  24  of the stud  10  of  FIG. 1 . However, the optional recess  26  of the stud  10  of  FIG. 1  has been omitted. The shaft portion  12 ′ might substantially have the same diameter as the shaft portion  12 , but presently includes an enlarged sub-portion having a greater diameter which might be required by a specific shape of a clip  40 ′ (not shown here). An axial length of the shaft portion  12 ′, including the sub-portion having the extended diameter, might be the same as for the shaft portion  12  of  FIG. 1 . The joining portion  18 ′ might have a greater diameter than the head portion  24 ′. The joining portion is following the shaft portion  12 ′ and also has a recess  20 ′, dimension of which is similarly chosen as for the recess  20  in  FIG. 1 . 
         [0049]    It is understood that the abovementioned features and those to be explained in the following can be applied, not only in the respectively specified combination, but also in other combinations or singly, without departure from the scope of the present invention. 
         [0050]    Although exemplary embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.