Patent Publication Number: US-2007098520-A1

Title: Bolt that can be pressed into a metal sheet in a torsion-proof and ejection-proof manner

Description:
The present invention relates to a bolt that can be pressed into a metal sheet in a torsion-proof and ejection-proof manner according to DE-Gbm 200 12 097 U1.  
      Since during the setting of bolts according to this reference, on the one hand, is accompanied by a flowing of the material of the metal sheet, on the other hand, however, a sealing only is consisting of a steel-steel material pairing, the connection between the bolt and the metal sheet according to the prior art is not safely tight against liquid or even gases.  
      It is therefore the task to be solved by the present invention to improve such a bolt in such a way that after the setting it is positioned in a fluid-- and gas-tight manner.  
      In this way, according to the invention, for the first time, such a bolt that can be pressed-in could be used in cases where it is necessary that the bolt after the setting is absolutely liquid-tight and gas-tight.  
      Until now to this end only commercial screws could be used which therefore however in a expensive way singularly had to be welded, wherein during the welding, too, a substantial expenditure with respect to inspection was necessary to ensure that the welding always was gas-tight. Therefore this method was extremely complicated and cost-intensive. According to the invention, this method in a far more simple way can be performed by pressing-in a bolt according to the invention.  
      The above-defined task therefore is solved by means of a bolt according to the preamble of the enclosed claim  1 , wherein the side of the head facing the metal sheet is provided with a rubber-elastic sealing material.  
      Preferred embodiments can be learned from the enclosed sub-claims, wherein it is especially preferred that the webs themselves are free from the sealing material since in this way a decreasing of the safety against torsion and ejection of the bolt by the covering with the sealing material is avoided.  
      In the same way, this can be prevented by the sealing material being provided exclusively in the region of the outer rim of the head facing the metal sheet.  
      In the same way, this further problem can be avoided by the fact that the sealing material exclusively is positioned in an annular groove in the head which is positioned outwardly of the radial extension of the webs but within the outer edge of the head facing the metal sheet. 
    
    
      The present invention, in the following, is more detailly described with respect to the exemplary embodiments shown in the drawings. In the drawings show:  
       FIG. 1 a  bolt according to the invention with a coating of the entire head except the webs in a lateral cross-sectional view;  
       FIG. 2  the head of the bolt according to  FIG. 1  from below;  
       FIG. 3 a  bolt according to the invention with the sealing material in the region of the outer edge of the head in a lateral cross-sectional view;  
       FIG. 4  the bolt of the head according to  FIG. 3  from below;  
       FIG. 5 a  further bolt according to the invention in a lateral cross-sectional view; and  
       FIG. 6  the head of the bolt according to  FIG. 5  from below. 
    
    
      As shown in  FIG. 1 , a bolt  10  according to the invention is consisting of a disk-shaped head  12  and a connected cylindrical winding support  14  having an exterior thread.  
      Between the thread and the head  12 , in the following order a calibration collar  16 , an annular projection  18  and an annullar groove  20  having a semi-circular cross-section are provided. On the bottom side of the head  12 , which is facing during the setting of the fastener the metal sheet, there are provided radially extending webs  22  having a radial extension in a basically uniform height and which merely in their radially exterior area  21  are flattened.  
      The head  12  is shown partly in cross-section, wherein on the right hand side the corresponding web  22  is shown in cross-section, too, while the corresponding web  22  on the left hand side is shown in a side view.  
      According to the invention, such a bolt can be set in a metal sheet in a fluid- and gas-tight manner by coating the head with a rubber-elastic sealing material. The coating can be performed in the most simple way by immersion, wherein the corresponding coating can be extended up to the calibration collar  16 . As a coating material in this case preferably epoxy resin is used, for example the product Rimlex® of the ANOCHROME-Group, Great Britain, which can be applied in a liquid state which later is forming a solid elastic sealing material. In such a case, the safety with respect to torsion and ejection of the bolt can be impaired slightly. The coating  110  shown in  FIG. 1  therefore is extending only onto the head itself, wherein the webs  22  are kept free from the coating. This, on the one hand, is more difficult to be produced compared with the above-disclosed simple solution according to the invention, on the other hand, is providing for higher mechanical load values of the set bolt.  
       FIG. 2  is showing the head  12  of the bolt according to  FIG. 1  from below. Because of the interrupted cross-hatching, the area provided with the sealing material  110  of the head  12  visible from below clearly can be seen. Equally clearly it can be seen that the webs  22  including their bevels  21  are not covered by the rubber-elastic sealing material.  
       FIG. 3  is showing a further embodiment of the bolt according to the invention. Same reference numerals are characterising here the same constituents as in  FIGS. 1 and 2  and the corresponding description here is not again repeated.  
      With respect to the bolt showing in  FIG. 3  according to the invention in the region of the outer edge of the head  12  facing the metal sheet a circumferential recess is provided being filled with the rubber-elastic sealing material  120 . Alternatively a corresponding sealing ring of polyurethane, polyamide, polytetrafluorethylene or polyolefins can be inserted into the recess. This solution has the advantage that the mechanical properties of the set bolt are not at all influenced by the sealing material.  
       FIG. 4  is showing the head of the bolt of  FIG. 3  from below, wherein the position of the annulus  120  of the rubber-elastic sealing material again clearly can be learned.  
       FIG. 5  is showing a further embodiment of the bolt according to the invention. Here the head  12  is having a slightly larger diameter and radially outwardly of the webs  22  an annular groove  134  is provided in the head  12  which therefore is extending within the outer edge  132  of the head  12  facing the metal sheet. This groove  134  is filled with the sealing material  130  or a corresponding sealing ring of polyurethane, polyamide, polytetrafluorethylene or polyolefins is inserted in the groove  134 .  
       FIG. 6  is showing the head of the bolt of  FIG. 5  from below. Here again the extension of the annular groove  134  is obvious.  
      As a rubber-elastic sealing material  110 ,  120 ,  130  here preferably when coating the head epoxy resin is used, wherein in connection with the solutions according to FIGS.  3  or  5  preferably polyurethane, polyamide, polytetrafluorethylene or a mixture of polyolefins is used.