Patent Publication Number: US-2022235805-A1

Title: Functional Element, Component Assembly and Method of Manufacturing a Component Assembly

Description:
The invention relates to a functional element for pressing into a workpiece, in particular into a sheet metal part, to a component assembly that has a workpiece having a hole, in particular a sheet metal part, and such a functional element, and to a method of manufacturing a component assembly. 
     Such elements usually have a functional section that in turn serves to fasten further components. They are widely used in the automotive industry, among others. 
     Functional elements can be bolt elements, whose shafts can be provided with a thread, or nut elements that can, for example, have an internal thread. 
     Functional elements are known in different designs. On the one hand, there are, for example, rivet elements that have a rivet section that is deformed on the attachment to a sheet metal part to form a rivet bead and to form a ring-shaped receiver for the margin of a hole in the sheet metal part with the head part. With such rivet elements, the functional element is therefore deformed on the attachment to the sheet metal part. Furthermore, press-in elements are known in which the element itself is not intentionally deformed on the attachment to a sheet metal part, but the sheet metal material itself is deformed to bring it into engagement with undercuts of the respective press-in element. 
     To seal connections between functional elements and workpieces, in particular sheet metal parts, a coating provided for this purpose is usually applied to parts of the functional elements that contact the workpiece. The application takes place in a separate manufacturing step that leads to an increased effort and thereby to higher costs and an increased time requirement. In addition, this solution causes an increased environmental impact due to the coating. 
     It is an object of the present invention to provide a functional element and a component assembly by which a tight connection can be achieved with comparatively little effort and a reduced environmental impact can be achieved compared to previously known solutions. 
     This object is satisfied by the subjects of the independent claims. Advantageous embodiments are the subject of the dependent claims. 
     A functional element in accordance with a first aspect of the invention is suitable for being pressed into a workpiece, in particular into a sheet metal part, and comprises a functional section; and a fastening section having an abutment surface for introducing a press-in force into the functional element; a workpiece contact surface that is disposed opposite the abutment surface, that can be brought into contact with the workpiece, and that is in particular of a flange-like design; and a sealing region for receiving displaced material of the workpiece, said sealing region being disposed between the workpiece contact surface and the functional section in an axial direction and/or a radial direction of the functional element. The sealing region forms a contact surface for the displaced material to seal a connection between the functional element and the workpiece, wherein the contact surface has a first part surface, which extends obliquely to the axial direction of the functional element and which converges viewed in a press-in direction of the functional element, and a second part surface that adjoins the first part surface, that extends obliquely to the axial direction of the functional element, and that diverges viewed in the press-in direction of the functional element. 
     The second part surface directly or indirectly adjoins the first part surface. 
     Due to the converging first part surface and the diverging second part surface, which adjoins the first part surface, the contact surface is formed that is designed such that the displaced material of the workpiece can be optimally pressed against the contact to achieve a high tightness. 
     The functional element can in particular be a press-in bolt, in particular a press-in bolt having a flange, or a nut element, said press-in bolt and nut element preferably being used with ductile sheet metal parts to facilitate the press-in process. In this respect, in the press-in bolt, the shaft preferably has an external thread and forms the functional section. The nut element, in contrast, preferably has an internal thread that forms the functional section. Instead of the threads, other features can also be provided that are e.g. suitable for fastening a further component or for providing another functionality. The functional section can also be sectionally or completely formed as a smooth pin or a smooth hole. The fastening section is the section of the functional element with which the functional element is fastened to the workpiece. 
     The press-in direction designates the direction in which the functional element is pressed into the sheet metal part. The press-in direction can in particular extend in the direction of the axial direction of the functional element, and indeed preferably from the abutment surface in the direction of the workpiece contact surface. The abutment surface and/or the workpiece contact surface expediently preferably extends/extend approximately perpendicular to the press-in direction for the purpose of an effective force introduction. 
     The functional section and the fastening section are preferably formed in one piece. The functional element and/or the workpiece can be composed of metal. However, the concept in accordance with the invention can also be implemented with elements and/or workpieces composed of other materials. 
     The functional element can generally be self-punching. 
     Advantageous embodiments of the invention are set forth in the claims, in the description, and in the enclosed drawings. 
     The first part surface is preferably inclined approximately 20° to approximately 40°, in particular approximately 30°, with respect to the axial direction. The first part surface thereby has a comparatively small inclination with respect to the axial direction such that the material of the workpiece can be pressed tightly against the first part surface. 
     In a preferred embodiment, the second part surface is inclined approximately 50° to approximately 70°, in particular approximately 60°, with respect to the axial direction. The second part surface is thereby comparatively strongly inclined with respect to the axial direction, whereby an undercut can also be formed by means of the second part surface in addition to the sealing function. The functional element is thereby securely held in or at the workpiece. 
     The first part surface and the second part surface can in particular extend approximately at a right angle to one another. 
     The first part surface and/or the second part surface can expediently be conical such that they each form a surface against which the material of the workpiece can be tightly pressed. 
     The first part surface is preferably connected to the second part surface by a rounded transition region to avoid hollow spaces at the transition from the first part surface to the second part surface and leaks resulting therefrom. A radius of the curvature of the transition region can in particular be in the range of approximately 0.5 mm or less, in particular approximately 0.25 mm to 0.35 mm. 
     A functional element in accordance with a further aspect of the invention is suitable for pressing into a workpiece, in particular into a sheet metal part, and comprises a functional section and a fastening section having an abutment surface for introducing a press-in force into the functional element; a workpiece contact surface that is disposed opposite the abutment surface, that can be brought into contact with the workpiece, and that is in particular of a flange-like design; and a sealing region for receiving displaced material of the workpiece, said sealing region being disposed between the workpiece contact surface and the functional section in an axial direction and/or a radial direction of the functional element. The sealing region forms a contact surface for the displaced material to seal a connection between the functional element and the workpiece, wherein the fastening section has a projection that bounds the sealing region in the axial direction and that has a first flank facing the sealing region and a second flank that is remote from the sealing region and that extends obliquely and inclined to different degrees with respect to the axial direction. 
     The projection can in particular in the peripheral direction be provided peripherally at the shaft of a functional element designed as a bolt element and can also be designated as a lip. The projection preferably projects radially outwardly and comprises at least the first flank and the second flank. The first flank can in particular form at least a part of the contact surface, in particular the second part surface. 
     An undercut is formed by the projection, said undercut terminating the sealing region and securely holding the functional element in the workpiece. The displaced material of the workpiece can thereby be enclosed in the axial direction between the workpiece contact surface or the contact surface, on the one hand, and the projection, on the other hand. At the same time, the projection, in particular the first flank, can also form a part of the contact surface to achieve a high sealing effect. 
     The first flank is preferably more inclined with respect to the axial direction than the second flank. The effect of the undercut, that is the hold of the functional element in the workpiece, is thereby improved, on the one hand, and, on the other hand, the insertion of the functional element is facilitated on the pressing of the functional element into the workpiece in the press-in direction in which the second flank projects. 
     The first flank can in particular be inclined approximately 50° to approximately 70°, in particular approximately 60°, with respect to the axial direction. 
     In a preferred embodiment, the second flank is inclined approximately 15° to approximately 35°, in particular approximately 25°, with respect to the axial direction. 
     The first flank and the second flank can expediently be connected to one another by a connection section in which the projection has a constant diameter such that the design of the projection can be adapted to the circumstances, in particular of a sheet metal thickness of the workpiece, without impairing the function of the flanks. In this embodiment, the connection section thus extends in the axial direction. The connection section can preferably extend over approximately 20% to approximately 70%, in particular approximately 40%, of the axial extent of the projection. 
     The fastening section, for example the workpiece contact surface, in particular has at least one feature providing security against rotation. A plurality of features providing security against rotation are preferably provided that are, for example, arranged uniformly distributed in the axial direction and/or the peripheral direction. It can be ensured by the features providing security against rotation that a connection of the functional element to the workpiece can withstand a torque load subsequently introduced via the functional section. The features providing security against rotation can be arranged in a recess or a peripheral groove of the fastening section, in particular of a head of the functional element that comprises the abutment surface and/or the workpiece contact surface. 
     The features providing security against rotation can be configured as radially and/or axially extending ribs or grooves. The features providing security against rotation are in particular uniformly arranged and extend at equal angular spacings from one another in the radial direction. 
     The workpiece contact surface can have a recess, in particular a ring recess, with the first part surface preferably being able to extend into the recess and/or merge into it. 
     In accordance with an embodiment, the workpiece contact surface has—in addition or alternatively to the recess—an elevated portion. The elevated portion can at least sectionally be of wedge-shaped design viewed in a cross section. The wedge shape preferably slopes toward the first part surface. The first part surface can merge into the elevated portion. 
     One function of the elevated portion can be to assist in a displacement of material of the workpiece into the sealing region on a cooperation of the element with the workpiece. 
     The features providing security against rotation—if present—can be arranged in the recess and/or at the elevated portion. 
     The recess can in particular be directed opposite to a press-in direction of the functional element such that the material of the workpiece is displaced, at least partly, on the pressing into the recess and is there in particular pressed against the first part surface of the contact surface. 
     In an advantageous embodiment, the workpiece contact surface merges into the first part surface. 
     The invention further relates to a component assembly that has a workpiece, in particular a sheet metal part, wherein a functional element in accordance with at least one of the embodiments described above is pressed into a hole prefabricated in the workpiece or into a hole punched by the functional element. In this respect, the functional element in accordance with the invention is pressed into the hole such that material of the workpiece displaced by the pressing in or after the pressing in is received in the sealing region and tightly contacts the contact surface. 
     The displaced material of the workpiece in particular contacts the projection or at least partly or completely surrounds the projection. 
     A thickness of the workpiece can be smaller than or substantially equal to an axial extent of the sealing region at least in the region of the hole. 
     Alternatively, a thickness of the workpiece can, however, be greater than or substantially equal to an axial extent of the sealing region at least in the region of the hole. 
     In accordance with a further aspect, the invention further relates to a method of manufacturing a component assembly in accordance with the invention that comprises the following steps:
         providing a functional element in accordance with the invention;   providing a workpiece, in particular a sheet metal part; and   inserting the functional element into a prefabricated hole in the workpiece or into a hole punched by the functional element and introducing a press-in force into the abutment surface such that the workpiece contact surface is brought into contact with the workpiece; and   displacing material of the workpiece into the sealing region such that the material is pressed against the contact surface to establish a sealed connection between the functional element and the workpiece.       

     In accordance with an embodiment, the functional element is self-punching such that a pre-punching of the workpiece is unnecessary. 
     The displacement of the material can take place by pressing a die against a surface of the workpiece remote from the workpiece contact surface. In this respect, the die is suitably designed to displace the material of the workpiece into the sealing region such that the material is pressed against the contact surface to establish a sealed connection between the functional element and the workpiece. 
     In the method, the workpiece is in particular disposed on a support that comprises a suitable die. The introduced press-in force then also serves to displace the material. However, it is also possible to press the die against the surface of the workpiece remote from the workpiece contact surface during or after the insertion of the functional element into the hole and/or the introduction of the press-in force in order to displace material of the workpiece. 
     The displacement of the material of the workpiece can also be caused by components of the head of the element during the pressing in. 
    
    
     
       The invention will be explained purely by way of example in the following with reference to advantageous embodiments. In the drawings, which schematically illustrate the embodiment examples, 
         FIG. 1  shows a perspective view of a functional element configured as a press-in bolt in accordance with an embodiment example; 
         FIG. 2  shows a further perspective view of the functional element from  FIG. 1 ; 
         FIG. 3 a    shows a half-section of the functional element from  FIG. 1 ; 
         FIG. 3 b    shows a detailed view of the region A in accordance with  FIG. 3   a;    
         FIG. 4  shows a detailed view of a sealing region of a functional element configured as a press-in bolt in accordance with a further embodiment example; 
         FIG. 5  shows a detailed view of a sealing region of a functional element configured as a press-in bolt in accordance with a further embodiment example; 
         FIG. 6 a    shows a half-section of a component assembly in accordance with an embodiment example with a press-in bolt as the functional element; 
         FIG. 6 b    shows a detailed view of the region B in accordance with  FIG. 6   a;    
         FIG. 7 a    shows a half-section of a component assembly in accordance with a further embodiment example with a press-in bolt as the functional element; 
         FIG. 7 b    shows a detailed view of the region C in accordance with  FIG. 7   a;    
         FIG. 8 a    shows a half-section of a component assembly in accordance with a further embodiment example with a press-in bolt as the functional element; 
         FIG. 8 b    shows a detailed view of the region D in accordance with  FIG. 8   a;    
         FIG. 9  shows a perspective view of a functional element configured as a nut element in accordance with an embodiment example; 
         FIG. 10  shows a further perspective view of the functional element from  FIG. 9 ; 
         FIG. 11 a    shows a half-section of the functional element from  FIG. 9 ; 
         FIG. 11 b    shows a detailed view of the region E in accordance with  FIG. 11   a;    
         FIG. 12 a    shows a half-section of a component assembly in accordance with an embodiment example with a nut element as the functional element; and 
         FIG. 12 b    shows a detailed view of the region F in accordance with  FIG. 12   a.    
     
    
    
     A functional element  10  configured as a press-in bolt having a flange can be seen from  FIG. 1  and  FIG. 2  in each case and  FIGS. 9 and 10  show a functional element  10  that is configured as a nut element, said functional elements  10  having a functional section  11  and a fastening section  13 . The fastening section  13  is the section of the functional element  10  with which the functional element  10  is fastened to a workpiece  50  that will be described in more detail in the following. The functional elements  10  each have a head  43 . The functional element  10  in accordance with  FIGS. 1 and 2  that is configured as a press-in bolt also has a shaft  41  at which a thread  45  (external thread) is formed. An internal thread  45  (see  FIG. 11 a   ) is provided at the functional element  10  configured as a nut element. 
     The respective head  43  has an abutment surface  15  for introducing a press-in force into the functional element  10  and a flange-like workpiece contact surface  17  disposed opposite the abutment surface  15 . In an axial direction and/or a radial direction of the functional element  10 , a sealing region  19  is located between the workpiece contact surface  17  and the functional section  11 , said sealing region  19  having a contact surface  21  for displaced material of the workpiece  50  to seal a connection between the functional element  10  and the workpiece  50 . 
     The shaft  41  of the element  10  of  FIGS. 1 and 2  extends from the side remote from the abutment surface  15 . However, it is also possible to arrange the shaft at the abutment surface  15  (the abutment surface  15  would then be ring-shaped in the case of a shaft having a round cross-section). With an otherwise unchanged design of the fastening section  13 , the sealing region  19  is then likewise disposed between the workpiece contact surface  17  and the functional section  11  in an axial view. 
     The design of the contact surface  21  is clearly shown in  FIGS. 3 a    to  FIG. 5 . The contact surface  21  comprises a conical first part surface  23 , which extends obliquely to the axial direction of the functional element  10  and converges viewed in a press-in direction E of the functional element  10 , and a conical second part surface  25  that, viewed in the press-in direction E, is disposed between the first part surface  23  and the functional section  11 , that adjoins the first part surface  23  by means of a rounded transition region  27 , that likewise extends obliquely to the axial direction of the functional element  10 , and that diverges viewed in the press-in direction E of the functional element  10 . 
     Specifically, the first part surface  23  can be inclined approximately 20° to approximately 40°, in particular approximately 30°, with respect to the axial direction and the second part surface  25  can be inclined approximately 50° to approximately 70°, in particular approximately 60°, with respect to the axial direction. As can, for example, be seen from  FIG. 3 b    and  FIG. 4 , the two part surfaces  23 ,  25  can extend approximately at a right angle to one another. Alternatively, as shown in  FIG. 5 , the angle between the part surfaces  23 ,  25  can also be greater than 90°, for instance up to 135°. 
     As the embodiment example in  FIGS. 11 a  to 12 b    clearly shows, the contact surface  21  of the functional element  10  designed as a nut element also comprises a first part surface  23  and a conical second part surface  25  that adjoins the first part surface  23  by means of a rounded transition region  27 , that extends obliquely to the axial direction of the functional element  10 , and that diverges viewed in the press-in direction E of the functional element  10 . In the present example, the first part surface  23  extends approximately in parallel with the press-in direction E; however, the functional element  10  can also be designed such that the first part surface  23  extends obliquely to the axial direction and converges viewed in the press-in direction E, as indicated by dashed lines in  FIG. 11   b.    
     The press-in direction E in this respect designates the direction in which the functional element  10  is pressed into the sheet metal part  50  as intended. The press-in direction E extends in parallel with the axial direction of the functional element  10  from the abutment surface  15  in the direction of the workpiece contact surface  17 , with the abutment surface  15  and the workpiece contact surface  17  extending approximately perpendicular to the press-in direction E. 
     The contact surface  21 , and indeed the first part surface  23 , extends into a (ring) recess  39  of the elements  10  formed in the head  43  in accordance with  FIGS. 1 to 8   b  and merges there into the workpiece contact surface  17 . A plurality of radially extending ribs are formed in the recess  39  as features providing security against rotation  37 . The recess  39  is further directed opposite to the press-in direction E of the functional element  10  such that material of the workpiece  50  can at least partly be displaced on the pressing into the recess  39  and in so doing lies against the first part surface  23 . 
     The element  10  in accordance with  FIGS. 9 to 11  b does not have this recess  39 . Instead, a wedge-shaped elevated projection  40  is provided that slopes radially inwardly and merges into the first part surface  23  via a rounded transition section  28 . In the embodiment example shown, the surface  23  has features providing security against rotation  37  in the form of axial ribs uniformly distributed in the peripheral direction. The elevated portion also preferably has features providing security against rotation  37 , here as an example radial grooves uniformly distributed in the peripheral direction. 
     If required, the recess  39  described above and the elevated portion  40  can be combined—also in a modified form—and are implemented both in a nut element and in a bolt element. 
     The fastening section  13  furthermore comprises a projection  29  that extends peripherally radially outwardly and that bounds the sealing region  19  in the axial direction. The projection  29  has a first flank  31 , which faces the sealing region  19  and at which the second part surface  25  of the contact surface  21  is formed, and a second flank  33  remote from the sealing region  19 . Furthermore, the projection  29  of the functional element  10  configured as a press-in bolt has, unlike the nut element, an optional connection section  35  that connects the two flanks  31 ,  33  to one another. The diameter of the projection  29  varies along its axial extent and, viewed in the press-in direction E, increases in the region of the first flank  31 , remains constant in the region of the connection section  35 , and decreases in the region of the second flank  33 . Accordingly, the flanks  31 ,  33  extend obliquely to the axial direction of the functional element  10 . 
     As in particular  FIG. 4  shows, the first flank  31  can be more inclined with respect to the axial direction than the second flank  33 . On the one hand, a particularly effective design of the contact surface  21  and an effective undercut by the projection  29  hereby result. On the other hand, a comparatively slight positioning or inclination of the second flank  33  facilitates the insertion of the projection  29  into the shaped hole. 
     Alternatively thereto, the projection  29  can be of approximately symmetrical design, whereby an equal inclination of the flanks  31 ,  33  with respect to the axial direction (see, for example,  FIG. 3 b   ) results or the first flank  31  can be less inclined with respect to the axial direction than the second flank  33  as shown in  FIG. 5 , for example. Specifically, the first flank  31  can advantageously be inclined approximately 50° to approximately 70°, in particular approximately 60°, with respect to the axial direction and the second flank  33  can be inclined approximately 15° to approximately 35°, in particular approximately 25°, with respect to the axial direction. 
     The cooperation of the functional element  10  with the workpiece  50  can be clearly seen in particular from  FIGS. 6 a  to 8 b    and  FIGS. 12 a  and 12 b    that each show a component assembly  100  in accordance with the present invention. As shown, the workpiece  50  is in each case by way of example configured as a sheet metal part having preferably ductile properties. The workpiece  50  in each case has a surface  51  which the workpiece contact surface  17  of the functional element  10  contacts and a surface  53  at an oppositely disposed side of the workpiece  50 . The workpiece  50  that is in each case shown in  FIGS. 6 a , 6 b , 7 a , 7 b  and 8 a , 8 b    has increasing thicknesses T 50  to illustrate that the concept in accordance with the invention can be used with workpieces having the most varied properties. 
     The functional element  10  is in each case pressed into a shaped hole provided in the workpiece  50 , for example a bore or a pre-punched hole, such that displaced material of the workpiece  50  and in the sealing region  19  and—if present—in the recess  39  is received and tightly contacts the contact surface  21 . This is simplified by the oblique arrangement of the first part surface  23  since the material does not have to be pressed so deeply into the sealing region  19  to come into areal contact with said first part surface  23 . In this respect, depending on the thickness T 50  of the workpiece  50 , the displaced material of the workpiece  50  contacts the projection  29  ( FIG. 6 b   ,  FIG. 8 b   ,  FIG. 12 b   ) or even completely surrounds it ( FIG. 7 b   ). The functional element  10  in accordance with the invention thereby enables the manufacture of excellently sealed component assemblies  100 , and indeed irrespectively of a thickness T 50  of the respective workpiece  50 . 
     The following procedure can in particular be followed to manufacture the component assemblies  100  shown in  FIG. 6 a    to  FIG. 7   b:    
     First, a functional element  10  in accordance with the invention and a workpiece  50 , in particular a sheet metal part in which a shaped hole is formed, are provided. The functional element  10  is then inserted into the shaped hole such that the workpiece contact surface  17  faces the surface  51 . 
     In this respect, a press-in force is introduced into the abutment surface  15  and causes the workpiece contact surface  17  to be brought into contact with the workpiece  50 . This press-in force can be used such that material of the workpiece  50  is urged into the sealing region  19  and pressed against the contact surface  21 . For this purpose, a die that is not shown in the Figures can be provided on the surface  53  remote from workpiece contact surface  17 . Due to the press-in force, a punch of the die is pressed into the surface  53 , wherein a ring groove  55  is formed in a region of the workpiece  50  adjoining the hole. Thus, the pressing of the punch of the die into the workpiece  50  into a region adjoining the hole thus displaces material of the workpiece  50  that flows into the sealing region  19  and in so doing lies against the contact surface  21 . 
     It is generally also conceivable to first insert the element  10  into the workpiece  50  and to effect the step of displacing the material by means of the die in a separate and/or subsequent step. 
     In the component assembly  100  of  FIGS. 8 a   ,  8   ab , the displacement of the material is not effected by a die having a punch, but the surface  53  of the workpiece  50  is rather disposed on a substantially planar support surface in the region around the hole. Here, the displacement of the material is effected by partially pressing the head  43  into the surface  51 . Due to the planar support surface, the material cannot escape downwardly and is therefore urged into the sealing region  19  until it areally and thus tightly contacts the first part surface  23 . 
     In the component assembly  100  in accordance with  FIGS. 12 a   ,  12   ab , the displacement of the material is effected by the elevated portion  40 . The head  43  is not pressed into the workpiece  50 , but is merely pressed against its surface  51  until the workpiece contact surface  17  contacts it. In this respect, the elevated portion  40  penetrates the workpiece  50 . Its radially inwardly sloping wedge shape supports a directed displacement of the material into the sealing region  19 . 
     It is understood that the above-described concepts of the displacement of the material can be combined if it is useful in the respective application. 
     The embodiment examples shown and described here have in common that they provide a functional element or a component assembly that enable a sealed connection of a component assembly with little effort and without additional sealing means. Due to a suitable selection of the design, in particular a spatial arrangement, extent and/or inclination, of the first and second part surfaces, the first and second flanks, the transition section and/or the connection section, the functional element can be adapted to the respective conditions present. 
     The above embodiment examples relate to functional elements that can be inserted into pre-punched workpieces. However, it is also possible for these elements to be self-punching, in particular nut elements or bolt elements whose shafts extend from the abutment surface. Their fastening sections can for this purpose be provided with a punching edge facing the workpiece. 
     REFERENCE NUMERAL LIST 
       10  functional element 
       11  functional section 
       13  fastening section 
       15  abutment surface 
       17  workpiece contact surface 
       19  sealing region 
       21  contact surface 
       23  first part surface 
       25  second part surface 
       27  transition region 
       29  projection 
       28  transition section 
       31  first flank 
       33  second flank 
       35  connection section 
       37  feature providing security against rotation 
       39  recess 
       40  elevated portion 
       41  shaft 
       43  head 
       45  thread 
       50  workpiece 
       51  surface 
       53  surface 
       55  ring groove 
       100  component assembly 
     E press-in direction 
     T 50  thickness of the workpiece