Patent Publication Number: US-7594421-B2

Title: Bolt element having a shaft part and a spherical head, component assembly and method for the manufacture of a bolt element

Description:
CROSS REFERENCE OF APPLICATION 
     This application is a divisional application of U.S. patent application Ser. No. 10/250,451, filed Dec. 12, 2003 now U.S. Pat. No. 7,048,463 which claims the benefit of priority under 35 U.S.C. §119 from PCT/EP01/15370 filed on Dec. 28, 2001 and from German Patent Application No. 10065670.6, filed on Dec. 29, 2000, the contents of all of which are incorporated herein by reference. 
    
    
     The present invention relates to a bolt element having a shaft part which is designed at a first end for a rivet connection to a panel element, in particular to a sheet metal part. Furthermore, it relates to a component assembly comprising a bolt element of this kind with a component as well as to a method for the manufacture of such a bolt element. 
     A bolt element of the initially named kind is known from the International Application PCT/EP00/06465 or from the corresponding German Patent Application 100 33 149.1 as well as from the International Application PCT/EP00/06468 and from the corresponding German Patent Application 100 22 152.1. 
     One problem in mechanical engineering is to manufacture favourably priced bolt elements with a spherical head. Such bolt elements are for example used as hinge elements for damped spring supports which are used to support boot lids or bonnets (hoods) of motor cars. Such hinge elements are however also found in a plurality of other constructions, for example in linkages in the actuation mechanism of carburettors and the like. 
     The known spherical bolt elements have a thread at the shaft part and a flange projecting radially from the thread so that the bolt element can be fixedly installed on a sheet metal part or carrier. This design of the shaft part of the bolt element also makes it difficult to manufacture the spherical head because it gives rise to restrictions in the design of the cold heading tools for the spherical head. 
     In the known bolt elements for the spherical head it is problematic that when these are to be manufactured at favourable cost as cold headed parts the movable tool parts which form the spherical head have to move radially towards the longitudinal axis of the bolt elements and that burrs form at the surface of the spherical head at the partition surfaces, i.e. where these tool parts meet one another, with the burrs each lying in a radial plane. These burrs, even if they are fine in nature must either be removed in a costly manner in a further process or one was must accept the disadvantage that the burrs relatively quickly lead to wear of the socket which receives the spherical head, irrespective of whether the socket consists of plastic or metal. 
     The object of the present invention is to provide a bolt element with a spherical head which can be manufactured at extremely favourable cost and nevertheless does not have any disturbing burr. Moreover, a favourably priced attachment of a bolt element to a component should be made possible, so that the corresponding component assembly can likewise be obtained at a favourable price. Furthermore, a favourably priced method for the manufacture of a corresponding bolt element is to be provided. 
     In order to satisfy this object a bolt element of the initially named kind is provided with the special characterizing feature that the shaft part has at its other end a spherical formation, the ball diameter of which is larger than that of the shaft part. 
     In other words the bolt element in accordance with the invention consists essentially of a spherical head and a cylindrical shaft part, which is hollow at its end remote from the spherical head in order to enter into a rivet connection with a panel element, in particular with a sheet metal part. Since the diameter of the shaft part is constant, the functional element can be manufactured in that a cylindrical blank is received partly in a cylindrical passage of a die and projects beyond the end face of the die, in that a hemispherical recess is formed in the die in the region of the transition of the passage into the end face with the ball diameter of the hemispherical recess corresponding to the ball diameter of the desired spherical formation of the bolt element, in that a tool with a likewise hemispherical recess is pressed onto the free end of the cylindrical blank projecting out of the die and the die and the tool are brought into contact with one another in order to reshape the end of the cylindrical blank projecting out of the die to the spherical formation by cold deformation. 
     Whereas, in the prior art, the cold heading tools which are used for the manufacture of the spherical head have to be moved in the radial direction relative to the longitudinal axis of the corresponding blank in the invention the tools, of which there are only two, namely the die and the tool which cooperates with it, are, so to say, arranged coaxially to the cylindrical blank and are moved towards one another in order to produce the spherical formation by cold deformation of the cylindrical blank. This signifies that in the closed state of the die and of the tool, i.e. when these contact one another at a partition surface this partition surface is located at a position which corresponds to an equator of the spherical formation and stands perpendicular to the longitudinal axis of the cylindrical blank or of the shaft part of the bolt element. 
     In this design it is on the one hand possible to guide the die and the tool in such a way that they are strictly aligned relative to one another and that only an extremely small burr is formed in the region of the equator, if at all. This burr is however also no longer so disturbing because it does not exert any pronounced scraping action on the socket on rotating the socket about the longitudinal axis of the spherical head, as is the case of a burr which extends in a radial plane. Because the shaft part of the functional element is made at least substantially cylindrical and has a constant outer diameter, the cylindrical blank can be made at extremely favourable cost from cylindrical bar material or wire or can be manufactured from tube material. A radial movement of the parts of the die or of the tools in order to take account of the features of shape of the shaft parts is no longer necessary, since no such features of shape are present in a purely cylindrical shaft part. 
     Through the design of the rivet connection in accordance with the manner described in the above-named PCT applications, or in the corresponding German patent applications, it is nevertheless possible to secure the corresponding bolt element at favourable cost and with adequate strength to a component or to a sheet metal part. 
     In the first case (in the case of PCT/EP00/06465) the bolt element has a form designed there as a head part in the shape of a hollow cylinder which is equipped with piercing and riveting features and which is introduced in a self-piercing manner into a sheet metal part. In this arrangement the free end of the hollow head part is formed over to a rivet bead at one side of the sheet metal part and the wall of the cylindrical part is formed into a ring fold at the other side of the sheet metal part, so that the sheet metal part is clamped between the rivet bead and the ring fold. In this way a stable connection arises between the bolt element and the sheet metal part. 
     In the second case (in the case of the PCT Application PCT/EP00/06468) the bolt element likewise has a section termed there as the head section which is again formed as a hollow cylinder but which is strongly rounded at its open end face and thus has in total a cigar-like shape. 
     In both cases the respective element has an at least substantially constant diameter over its entire length in preferred embodiments. 
     In the case of the cigar-like element this is not introduced in self-piercing manner into the sheet metal part, but rather the hollow region of the bolt element is exploited to press the sheet metal part into a shaping space of a die and is deformed during this into two axial ring folds spaced from one another by a ring recess with the sheet material being pressed into the ring recess and thus producing a stable rivet connection between the bolt element and the sheet metal part. The shaft parts of the respective bolt elements are normally provided with an outer thread. Other formations, such as a peripherally extending groove to receive a spring clamp are also described. The disclosures of the above designated international applications or of the corresponding German applications are also made part of the content of the present application since the designs respectively described there, for the rivet connections to the sheet metal part, can be used in identical form in the present invention and represent preferred embodiments of the rivet connection which will be used for the present invention. 
     In both cases the deformation of the hollow region of the shaft part at its first end remote from the spherical head leads to an adequately broad ring fold which enables a good attachment to the sheet metal part and so to say forms a broad base so that forces which act in the radial direction on the spherical head do not lead to a loosening of the bolt element. 
     Particularly preferred embodiments of the bolt element and also of the component assembly, of the method and also of the die and tools in accordance with the present invention can be taken from the description of the Figures and also from the subordinate claims. 
    
    
     
       The invention will now be explained in more detail with reference to embodiments and to the drawing in which are shown: 
         FIG. 1  a bolt element in accordance with the invention sectioned partly in the longitudinal direction, 
         FIG. 2  the tools used in accordance with the invention for the manufacture of the bolt element of the invention of  FIG. 1 , 
         FIG. 3  a diagram corresponding to  FIG. 5  of the PCT Application PCT/EP00/06465 in order to explain the attachment of the bolt element of the invention to a sheet metal part, 
         FIG. 4  a Figure corresponding to  FIG. 2  of the PCT Application PCT/EP00/06468 in order to show the use of the rivet connection of this PCT Application in the present invention, 
         FIG. 5  a representation sectioned in the longitudinal direction of a spherical bolt element, which was manufactured from tube material, 
         FIG. 6  a similar illustration to that of  FIG. 6  of a spherical bolt element which was manufactured by means of an internal high pressure forming process, 
         FIG. 7  a preferred tool for the attachment of spherical bolt elements, 
         FIG. 8  a detail of the die of  FIG. 7  in the region of the rectangle drawn in there without sheet metal part, 
         FIG. 9  the detail of  FIG. 8  after the attachment of the spherical bolt element and 
         FIGS. 10A to 10D  a series of sketches to illustrate different possible sheet metal preparation steps. 
     
    
    
     In the following description the same reference numerals will always be used for the same or similar parts and features, so that a description which has been given once of a part or of a feature also applies to a part or feature with the same number and the description need not be repeated. 
       FIG. 1  shows in a side-view a bolt element  10  in accordance with the invention and having a shaft part  12  which is designed at a first end  14  for a rivet connection  16  (see  FIG. 3 ) to a panel element  18  together with a sheet metal part. The shaft part  12  has at its other end  20  a spherical formation  22 , the ball diameter D of which is larger than the diameter d of the shaft part. 
     The diameter d of the shaft part  12  is at least substantially constant over at least substantially its whole length from the spherical formation  22  up to the end face  24  of the first end  14 . 
     The first end  14  of the shaft part  12  which is designed for the rivet connection  16  to the sheet metal part is made hollow and has at least substantially the same outer diameter d as the remainder of the shaft part  12 . The hollow space  26  which is formed in this way is, as shown in  FIG. 1 , at least substantially of circularly cylindrical shape. The first end  14  of the shaft part  12  is formed in a manner known per se with piercing and riveting features, and indeed in the form of a rounded punching and drawing edge  28  and has a conical cutting surface  30  at its inside. The piercing and riveting section of the bolt element  10  is thus formed in accordance with DE-PS 34 470 06 C2. The outer periphery of the shaft part  12  is preferably also made circularly cylindrical, i.e. it has in cross-section a circular periphery. It would however also be conceivable to use shapes of the shaft part  12  which differ slightly from the circular shape, for example a polygonal shape should this appear expedient for special reasons. 
     The hollow region  32  should have a minimum length L (measured in the direction of the central longitudinal axis  34  of the bolt element  10 ) to ensure that adequate material is present in the hollow region in order, during the formation of the rivet connection  16  of  FIG. 3 , to form the rivet bead  36  at the side  38  of the component  18  remote from the spherical formation  22 , to bridge the thickness of the component  18  and to form the ring fold  40  at the side  42  of the component  18  adjacent the spherical formation. 
     It is also conceivable to make the bolt element hollow as a whole which would have the advantage that the element could be manufactured from tube material and that the spherical formation could be manufactured by a high pressure shaping process inside a corresponding outer die. 
     When using a hollow shaft part this can optionally be provided with an internal thread whereby, after formation of the rivet connection of  FIG. 3  and removal of the stamping slug  44  shown there, a bolt could be introduced into the thread from the end of the bolt element  10  remote from the spherical formation  22  in order to additionally enhance the attachment to the sheet metal part, should this be necessary. A bolt element of this kind could also increase the stiffness of the bolt element itself. With such a design (not shown) it will be necessary to provide correspondingly shaped washers for a stable seating of the head of the bolt at the underside of the sheet metal part  18  for which it would be sufficient, under such circumstances, to provide the rivet bead  36  with a flattened lower side (in  FIG. 3 ) by a pressing process. 
     It is moreover evident from  FIG. 1  that the spherical formation  22  has an equator line  46  which lies in a plane which stands perpendicular to the longitudinal axis  34  of the shaft part. At the position of the equator line  46  there is essentially no burr, i.e. no raised portion to be found during the manufacture of the bolt element, but rather this equator  46  merely shows the position of the parting joint of the tools which are used to form the spherical formation. These tools are shown in more detail in  FIG. 2 . They comprise a lower die  50  and an upper tool  52 . The designation “lower” and “upper” relates here, as also at other points of the description and claims solely to the alignment of the drawing and does not represent any restrictions on the actual alignment of the die or of the tool. These parts could just as easily be arranged so that the die is disposed above the tool  52  or such that the central longitudinal axis  54  is arranged horizontally or in another direction. 
     The die  50  has a cylindrical passage  56  which merges, in the region of the end face  58  of the die, into a hemispherical recess  60  the spherical diameter of which corresponds to the diameter D of the spherical formation  22  of the bolt element  10 . Within the central passage  56  of the die there is located a cylindrical bar  55 , the upper end  64  of which is located in the hollow space  26  of the bolt element  10  and, for example, contacts the transverse wall  66  of the hollow space  26 . At its other, lower, end the bar  62  is supported on a firm support, as is the die  50 . The bar  62  is located within a sleeve  68  which can be moved to and fro in accordance with the double arrow  70  in order to eject the finished bolt element  10  out of the die. 
     Above the die  50 , and coaxially aligned with it, is a tool  52  which likewise has a hemispherical recess  74  at its end  70 , with this hemispherical recess  74  also merging into a circularly cylindrical passage  76  which is likewise arranged coaxial to the central longitudinal axis  54 . The reference numeral  80  points in this embodiment to a cylindrical guide which is located in the passage  76  and the lower end  82  of which serves to produce the flat  84  at the upper end of the spherical formation  22 . This guide  80  can also be biased with a spring device so that it can deflect by a small amount if, for tolerance reasons, too much material is present for the generation of the spherical formation  22 . 
     The manner of operation of the arrangement in accordance with  FIG. 2  will now be explained in more detail. Inititally all the bolt element  10  should be imagined to be missing. First of all a cylindrical blank (not shown) which has the hollow space  26  and the piercing and riveting features is introduced into the central passage  56  of the die  50  so that the transverse wall  66  is supported on the upper side of the bar  54 . The ejection sleeve  68  is retracted in this state so that the lower end face  24  of the blank has a distance from the sleeve  68  or can press this away with a light contact pressure. The upper die  52  is now guided downwardly under the guidance of the guide bar  80  and deforms the upper end of the cylindrical blank into the spherical form  22 . At the end of the movement of the tool  52  towards the die  50  the lower end face  72  of the tool  52  is in contact with the upper end face  58  of the die  50  and the partition joint, i.e. the position at which the end faces  72  and  58  contact one another, is so selected that it lies on the equator line  46  of the spherical formation. The cylindrical blank is so dimensioned that it projects prior to the closing movement of the tool  52  against the die  50  beyond the end face  58  of the die  50  and indeed by an amount such that just sufficient material is present in order, in the closed state of the tools, i.e. with contact of the end face  72  of the tool  52  against the end face  58  of the die  50  to fill out fully the so formed spherical space. 
     As soon as the tools have reached this closed position the bolt element is finished, the tool  52  is moved upwardly again and away from the die  50  and the sleeve  68  is moved upwardly in order to eject the finished bolt element  10 , as shown in  FIG. 2 , out of the die  50 . Thereafter a new cylindrical blank can be inserted into the passage  56  and the method is repeated in order to manufacture a further bolt element. 
     The die  50  can be arranged in this manufacturing process and the lower tool of a press, whereas the upper tool  52  is attached to the upper tool of the press or to an intermediate platen of the press. 
     The method for attachment of the bolt element  10  to a sheet metal part  18  as shown in  FIG. 3  is described in detail in the above-mentioned PCT Application PCT/EP00/06465 and will not be explained here in further detail because the precise nature and design of the rivet connection is not the subject of the present invention. Since the lower end of the bolt element  10  is equipped with piercing and riveting features it can be introduced in self-piercing manner into the sheet metal part  18 , whereby the punching slug  44  arises. As shown in  FIG. 3  this punching slug is clamped into the deformed hollow space  26  of the bolt element  10  and contributes to the stability of the rivet connection  16 . The upper side  90  of the ring fold  40  is so arranged that it lies approximately in the same plane as the upper side  42  of the sheet metal part  18  and it does not therefore present any obstacle for the freedom of movement of a socket placed onto the spherical formation  22 . One can see from the shape of the (originally flat) sheet metal part in the region of the rivet connection  16  how an extremely stable attachment of the bolt element  10  to the sheet metal part  18  is provided. 
     The bolt element  10  need not essentially be executed as shown in  FIG. 1  but rather other designs of the first end  14  are conceivable which are also suitable for a rivet connection to a sheet metal part. In particular a design can be considered as shown in  FIG. 2  of the PCT Application PCT/EP00/06468. This design also enables a rivet connection  16 ′ as shown in  FIG. 4  and is likewise realized as set forth in the mentioned PCT Application. Advantageous for this type of rivet connection is the fact that the sheet metal part  18  is not pierced, so that a water-tight connection is present. As can be read in the corresponding PCT Application the rivet connection  16 ′ is effected here in such a way that the hollow region of the bolt element is formed into two ring folds and indeed an upper ring fold  40 ′ and additionally a lower ring fold  92  which form a ring-like recess  94  between them. The sheet metal material is pressed into this ring-like recess  94  by the attachment of the sheet metal element, as shown at  96  in  FIG. 4 , and is firmly clamped between the two ring folds  40 ′ and  92 . The reference numeral  98  points in this example to noses providing security against rotation which are important in the PCT Application if the corresponding element has to take up torques about the longitudinal axis. 
     Since one is concerned here with a bolt element with a spherical head, which does not have to take up any torques, such noses  98  providing security against rotation are not compulsory and the corresponding features of shape of the tools which are necessary to form theses noses providing security against rotation can be omitted. 
     In all embodiments all materials can be named as an example for the material of the functional elements which achieve the strength values of class 8 in the accordance with the Iso standard in the context of cold forming, for example a 35B2 alloy in accordance with DIN 1654. The so formed fastening elements are suitable, amongst other things, for all commercially available steel materials for example drawing quality sheet metal parts and also for aluminium or other alloys. 
       FIG. 5  shows an axial cross-section through a spherical bolt element  10  similar to the spherical bolt element  10  of  FIG. 1  but with the difference that the element was manufactured from tube material and thus has a through-going central passage  100  with a circular cross-section. The lower end of the element of  FIG. 5  can be formed in correspondence with the lower end of the bolt element of  FIG. 1  with piercing and riveting features in the form of a rounded pressing and drawing edge  28  and a conical cutting surface  30 , is however shown here in an embodiment in which the conical cutting surface  30  was reduced to a minimum, which is also possible. The lower end of the longitudinal passage  100  corresponds to the hollow space  26  of the spherical bolt element  10  of  FIG. 1  or forms this hollow space. 
     The spherical bolt element  10  is manufactured in accordance with the spherical bolt element  10  of  FIG. 1  in a tool corresponding to  FIG. 2  but with the difference, that the guide bar  80  is preferably provided with a cylindrical projection (not shown) which fits into the central longitudinal passage  100  of the tubular blank or of the spherical bolt element and extends downwardly approximately to the upper end of the guide bar  62  in order to support the tube material from the inside during the formation of the spherical head and to avoid undesired deformations of the tube material. The step between the bar  80  and the downwardly directed cylindrical process, which also serves as a guide spigot and is introduced into the central longitudinal passage of the element forms a radial shoulder which takes care of the flattening  84  at the upper end of the spherical head. 
       FIG. 6  shows an alternative design of a spherical bolt element  10  which is manufactured of tube material. In this case a circularly cylindrical tube section is laid into a two-part die (not shown) which has the outer shape of the finished spherical bolt element of  FIG. 6  as a hollow cavity. The lower end  24  in  FIG. 6  of the spherical bolt element  10  is supported against a transverse wall of a hollow cavity of the mould and hydraulic fluid is forced at high pressure into the interior of the tube section via the upper end of the tube section in  FIG. 6  by means of a suitable nozzle, so that the spherical shape of the spherical head is produced by the high pressure applied to the inner side. The two-part mould, which is not shown, but which is formed in the region of the spherical bolt elements in accordance with the tool  52  and the die  50  has a partition surface between the two halves of the mould at the level of the plane  102  which is shown in  FIG. 6 . After formation of the spherical bolt element  10  the mould is opened and the spherical bolt element can be moved from the mould, optionally with the aid of a slider which slides in the axial direction of the shaft part of the spherical bolt within one of the form halves and preferably presses against the lower end face  24  of the spherical bolt element  10  in  FIG. 6 . 
       FIG. 7  shows a preferred tool  104  for the attachment of a spherical bolt element, for example in accordance with  FIG. 1 , to a plate-like work-piece in the form of a sheet metal part  18 . The sheet metal part  18  is supported on the upper end face of a die  104  which, in its basic principles resembles the dies of the European Patent Application 99 120 559.2 and of the European Patent Application 00 931 155.6. In accordance with  FIG. 9  of the first named patent application the die  104  which is present here has a hollow body  106  with an end face  108  provided for the support of a sheet metal part merging via a conically tapering wall  110  into a space having an abutment element  112 , with the abutment element  112  being spaced from the conically tapering wall for the formation of a ring gap  113  which is wedge-like in cross-section. 
     In the wedge-like ring gap there are a plurality of segment-like shaped parts of the same design, for example from  1  to  8 , in particular  4  shaped parts  116  which are arranged around the longitudinal axis  118  of the die in the wedge-like ring gap  113  and are supported both at the conical wall  110  and also at the abutment element  112 . The shaped parts  116  can either be so arranged that they completely fill out the ring gap  113  around the longitudinal axis  118 , i.e. so that no structure is present between neighbouring shaped parts  116 , for example in accordance with  FIG. 10  of the EP Application 99 120 559.2, or fixed structure of the die can be provided between the adjacent shaped parts of the die, as in the die of EP Application 00 931 155.6 or of the earlier related die of the same inventor. 
     The abutment element is however designed in this embodiment somewhat differently than in the named EP applications. 
     First of all it is evident that the abutment element  112  has a ring-like, radially extending, collar  120  which engages into corresponding grooves  122  of the shaped parts, with the abutment element  112  being movable with the shaped parts in the axial direction  118  of the die  104 . The lower end  124  of the abutment element projects into a hollow space  126  of the die body  106  and is terminated there with a disk element  130  screwed on by means of a screw  128 . In this hollow space  126  there is a compression coil spring between the radially inwardly projecting shoulder  132  of the outer part of the die and the die  130 , with the compression coil spring being designed to draw the abutment element  112  downwardly and also the shaped parts  116  with the abutment element  112  via the ring-like collar  120  the maximum downward movement of the shaped parts is bounded by the upper side  134  of the ring shoulder against which the shaped parts enter into contact. This also restricts, via the collar  120  and the grooves  122 , the lowest possible position of the abutment element  122 . The upper end  136  of the abutment element  122 , which can be seen in enlarged form in  FIGS. 8 and 9 , forms a shaping space  138  for the tubular end  14  of the spherical bolt element  10 . This ring-like shaping space has a rolling surface  140  of semicircular shape in cross-section in its base region which is arranged significantly below the radially inwardly projecting noses  142  of the shaped parts  146 . The end face  143  of the central post  144  of the abutment element lies flush with the upper side  146  of the shaped parts in  FIG. 8 , which in turn lies flush with the upper side of the outer part  106  of the die  104  and of the tool (not shown), which accommodates the die. 
     The reference numeral  150  points to a ring spring element which holds the shaped parts to the abutment element. 
     As evident from  FIG. 8  the shaped parts have rounded edges  152 , which is evident from the double line execution. 
     Whereas, in the die, in accordance with the PCT Application PCT/EP00/06468 the sheet metal part is shaped into a pot-like recess during the stamping of the corresponding element into a shaping space of the die, the central post  144  cooperates with the piercing and riveting features  28 ,  30  of the lower end of the spherical bolt element  10  in order to punch out from the sheet metal part a punching slug  44  similar to the manner described for the shaping die of the German Patent DE-PS 34 47 006. 
     The lower end face  24  of the spherical bolt element punches through the sheet metal part  18  in collaboration with the upper end  143  of the central post of the abutment element  12  and draws the sheet metal part around the hole which is formed in this way over the rounded noses  142  of the shaped parts into the shaping space  138  of the die. At the same time the material of the tubular end of the spherical bolt element  10  is deflected radially outwardly, and then upwardly again, by the rolling surface of the abutment element of the die until the free end  24  of the spherical bolt element  10  abuts against the underside  154  of the radially inwardly projecting noses  142  of the shaped parts  116 . 
     One can see from  FIG. 9  that the conical shape  156  of the sheet metal part  18  in the shaping space  130  of the die now lies in form-fitted manner within the turned over end  14  of the spherical bolt element  10  and in that at least essentially the entire shaping space  138  is full of metal. As soon as this position is achieved the material of the spherical bolt element can no longer flow into the shaping space  138 , the length of the tubular collar is however so dimensioned that the previously mentioned ring fold  40  can form, which is shown in  FIG. 9 . The movement of the free end  24  of the spherical bolt element is effectively stopped at the lower side  154  of the noses of the shaped parts  116 , so that the ring fold  40  can now be formed. 
     One notes that the punching slug  44  which arose on punching through the sheet metal part is trapped between the upper end  143  of the central post  144  and the transverse wall  66  inside the hollow space  26  and there stiffens the connection to the sheet metal part. 
     During opening of the press after the punching in of the spherical bolt element  10  the spherical bolt element is first lifted and simultaneously lifts the sheet metal part to which it is now attached, out of the die. In doing so the shaped parts  116  jointly lift upwardly, together with the abutment element  112 , with the coil spring in the hollow space  126  being compressed until the forces which act in the region of the rivet bead  36  are sufficient to press the shaped parts  116  radially outwardly away from the rivet bead  36 , whereby the component assembly consisting of the spherical bolt element  10  and the sheet metal part  18  are freed from the die  104 . 
     The upper part  160  of the tool  104  of  FIG. 7  represents a setting head which is designed for the attachment of the spherical bolt element such as  10  to the sheet metal part  18  and for this purpose can be attached via a holder, not shown, to an upper tool  163  of a press or to an intermediate platen of a press or, in an inverse arrangement, to a lower tool of the press. 
     The setting head  160  is aligned here in order to achieve a central alignment of the spherical bolt element with the die and prevents a kinking of the bolt element when it is stamped into place. The die ensures a termination of the beading operation when the free end face  24  of the rivet bead  36  runs against the die insert, i.e. against the shaped parts  116  and thus a defined starting point for the bulging out of the shaft  16  for the formation of the ring flange  40  and indeed even when only one shaped part  116  is provided, which is fundamentally possible with a die construction similar to the EP application 00 931 155.6. 
     The setting head  160  has an outer tubular part  162  with a conical recess  164  at the lower end  166  in which, in turn, a plurality of shaped parts, for example four shaped parts  168 , are accommodated of which only the one shape part  168  is visible in  FIG. 7 . The shaped parts each have a conical outer wall  170  which is made complementary to the conical wall  164  of the outer part  162  of the setting head  160 . 
     In the lower region of the shaped parts in  FIG. 7  these have radially inwardly extending jaw faces  172  which engage on the shaft part  14  of the spherical bolt element  10  and are formed as part-cylindrical surfaces so that an areal contact at the spherical bolt element is possible, in order to ensure the required alignment of the spherical bolt element  10  with the central longitudinal axis  174  of the setting head, which stands coaxial to the central longitudinal axis  118  of the die. 
     In the upper region the shaped parts  168  have radially inwardly directed noses  176  which extend into a groove  180  in a displaceable sleeve  182  of the setting head  160 . The lower boundary  184  of the groove engages behind the noses so that the shaped parts  168  are compulsorily guided, i.e. axially movable with the sleeve  182 . 
     A ring spring  184  surrounds the shaped parts  168  and thus ensures that the shaped parts  168  are not lost. The sleeve  182  has in its upper region a radially outwardly directed collar  186  which is movable in a circularly cylindrical hollow space  188  of the outer part  162  of the tool  160 , with a radially inwardly directed ring shoulder  190  of the outer part  162  of the tool  160  bounding the hollow cavity  188  at the bottom and forming an abutment for the radially outwardly directed collar  186  of the sleeve  182 . 
     Within the upper region of the sleeve there is located a light compression coil spring  192 , the lower end  194  of which contacts a radially inwardly directed shoulder  196  of the sleeve  182  and the upper end of which in  FIG. 7  is braced against the upper tool  163  of the press. In this embodiment the spring thus lightly biases the sleeve in the direction radially downwardly. 
     A plunger pin  200  with a conical upper end  202  is located within a cylindrical bore  198  of the sleeve  182  in the lower region of the sleeve and is supported against a corresponding conical surface within the displaceable sleeve  182 , so that the plunger pin  200  cannot fall downwardly out of the sleeve  182 . Above the plunger pin  200  there is a grub screw  204  which is screwed into a threaded bore  206  of the displaceable sleeve to prevent the plunger pin  200  deviating upwardly. The screw connection between the grub screw  204  and the sleeve  182  ultimately also transmits the pressure forces, which coming from the upper tool  163  of the press, press the sleeve  182  and thus also the grub screw  204  and the plunger pin  200  downwardly. One can see that the plunger pin  200  comes into contact on the flat  84  at the upper end of the spherical bolt element  10 . 
     On closing the press the spherical bolt element cannot deflect upwardly and the downwardly directed forces lead to the above described piercing of the sheet metal part and also to the shaping of the lower end  14  of the spherical bolt element  10  and the formation of the ring fold  40 . When these shaping operations are concluded the lower end  16  of the upper tool  160  contacts the sheet metal part  18  and presses the latter against the lower tool in the form of the die  104 . 
     On opening of the press the upper tool  160  lifts the spherical bolt element  10  with the attached sheet metal part  18  out of the die so that the die releases the component assembly, as described above. The sheet metal part then strikes against other parts of the press (not shown) so that a downwardly acting force is exerted on the spherical bolt element. The spherical bolt element thus pulls the shaped parts partly out of the outer part of the upper tool to such an extent that the outwardly extending collar  186  comes into contact with the radially inwardly directed ring shoulder  190 . This axial movement is sufficient in order to release the spherical head from the shaped parts  168  since these can deflect radially outwardly when they are partly pulled out of the outer part of the upper tool. In order to favour this radially outwardly directed movement the shaped parts  168  have in the region of the axial upper ends of the jaw surfaces  172  inclined faces or shaped faces  208  which cooperate with the rounded spherical surface of the spherical head of the spherical bolt element. 
     The component assembly comprising the spherical bolt element and the sheet metal part can now be removed from the working area of the tool in accordance with  FIG. 7 . 
     Since the compression coil spring holds the shaped parts in the opened position a new spherical bolt element can be introduced from below into the upper tool and pressed upwardly (until the jaw surfaces  172  of the shaped parts again engage the shaft part  14  of the spherical bolt element  10  and the compression coil spring is compressed. The ring spring  205  which, for example consists of polyurethane and which presses the shaped parts  168  towards one another is made sufficiently strong to hold the sleeve  182  with the shaped parts  168  in the position shown in  FIG. 7  by friction at the conical wall  164 . The new spherical bolt element now adopts the position of the spherical bolt element  10  of  FIG. 7 . 
     A new sheet metal part  18  can now be introduced into the press and, as described previously, the new spherical bolt element can then be riveted to the new sheet metal part  18 . 
     Instead of inserting the bolt element from below, for example by hand, between the shaped parts or shaped segments  168  of the upper tool the spherical bolt elements  10  can be introduced in an automated embodiment through an obliquely aligned guide channel  210  into the space between the shaped parts. 
     If for example three shaped parts  168  are provided, the obliquely aligned guide passage can lead into the intermediate space between two of the segment-like shaped parts  168 . This makes it possible for the spherical bolt element  10  to move from the obliquely aligned position of the guide passage  210  into the vertically aligned position between the shaped parts  168 . A similar procedure is however also possible if the tool  160  is provided with four contacting shaped parts  168 , providing the necessary space for the guide passage  210  can be created. 
     The series of sketches  10 A,  10 B,  10 C and  10 D finally show that it is also possible to insert the spherical bolt element into thicker pieces of sheet metal. With sheet metal of approximately 1.5 mm thickness it is sufficient to pierce the sheet metal part  18  or, as is shown in  FIG. 10A , to pre-form a hole as at  212 . 
     For sheet metal thicknesses beyond 1.5 mm it is however favourable to carry out a sheet metal preparation step so that the sheet metal has the shape of  FIG. 10B  in the region of the hole  214 . A sheet metal preparation of this kind is for example described in connection with the so-called clamping hole riveting process (European Patent 539 793) and in connection with the so-called EBF elements in the PCT Application PCT/EP96/04188, which is why it is not repeated here.  FIG. 10C  shows that the inner diameter of the hole  215  corresponds during the preforming of the hole and preparation of the sheet metal part at least substantially to the outer diameter d of the lower end  14  of the spherical bolt element.  FIG. 10D  finally shows the position after the attachment of the element which is executed according to the PCT Application PCT/EP00/06465. 
     The possibility also exists of using the die of  FIG. 7  to attach the bolt element into the prepared sheet metal part, with no punching slug arising here because the sheet metal part is not pierced by the spherical bolt element. The installation situation presents itself similarly to that of  FIG. 10D  except that a nip is present between the beaded over end  24  of the rivet bead  36  and the sheet metal part which is produced by the noses  142  of the shaped parts  106  of the die  104 .