Method and device for producing grooved bolts

Abstract

The invention relates to a method for producing a bolt ( 10 ) with a head ( 12 ) which is provided with a circumferential groove ( 20 ) or channel, wherein the groove ( 20 ) or channel is produced by pressing a bulge ( 18 ) against the head ( 12 ) by means of a radially active closing tool ( 112 ).

1 . Method for producing a bolt ( 10 ) having a head ( 12 ), which is provided with a peripheral groove ( 20 ) or channel, characterised in that the groove ( 20 ) or channel is produced by pressing a bead ( 18 ) on the head ( 12 ) using a radially active closure tool ( 112 ). 
     
     
         2 . Method according to  claim 1 , characterised in that the bolt ( 10 ) is produced from a wire portion by twice pre-compressing the head ( 12 ) and final compression, with the bead ( 18 ) for the groove ( 20 ) being produced. 
     
     
         3 . Method according to  claim 2 , characterised in that, during pre-compression, the head ( 12 ) of the bolt ( 10 ) assumes the shape of two concentric cylinders ( 14 ,  16 ) which are located one on top of the other, the shaft-side cylinder ( 14 ) having a larger diameter than the cylinder ( 16 ) arranged thereabove, and in that, during final compression, there is produced on the upper end of the upper cylinder ( 16 ) a radially outwardly extending bead ( 18 ) which then forms the upper delimitation of the groove ( 20 ) or channel by the two concentric cylinders ( 14 ,  16 ) being surrounded by jaws ( 112 ) of a tool ( 100 ) which are provided with corresponding steps ( 114 ,  116 ) during the final compression operation so that only the uppermost end of the uppermost cylinder ( 16 ) can be deformed outwards during the final compression operation. 
     
     
         4 . Method according to  claim 3 , characterised in that the tool ( 100 ) for final compression is provided with a socket ( 102 ) which has a cylindrical opening ( 104 ) in which a cupping insert ( 106 ) for receiving the shaft ( 11 ′) of the precompressed bolt ( 10 ′) in the axial direction of the opening ( 104 ) is movably arranged and which widens upwards in a conical manner and in which there are moved downwards in an axial direction during the final compression operation the jaws ( 112 ) of the tool ( 100 ) which have at the outer sides thereof chamfered portions which correspond to the conical widening ( 110 ) so that they automatically close around the head ( 12 ) of the bolt ( 10 ) during the final compression operation. 
     
     
         5 . Method according to  claim 4 , characterised in that the stamp ( 122 ) which is required for final compression of the head ( 12 ) of the bolt ( 10 ) and for producing the bead ( 18 ) is designed in a hollow-cylindrical manner and is received in a hollow-cylindrical stamp retention member ( 124 ) in an axially displaceable manner and the stamp retention member ( 124 ) is designed in such a manner that it first presses the jaws ( 112 ) of the tool ( 100 ) downwards during the final compression operation so that they close around the head ( 12 ) of the bolt ( 10 ) and the stamp ( 122 ) is only then moved downwards in order to form the bead ( 18 ) as an upper delimitation of the groove ( 20 ). 
     
     
         6 . Device ( 100 ) for producing a groove ( 20 ) or channel on the head ( 12 ) of a bolt ( 10 ) in a non-cutting manner, characterised in that the device ( 100 ) comprises jaws ( 112 ) which are provided with corresponding steps ( 114 ,  116 ) and which engage around the head ( 12 ) of the bolt ( 10 ) during the final compression operation. 
     
     
         7 . Device ( 100 ) according to  claim 6 , characterised in that it is provided with a socket ( 102 ) which has a cylindrical opening ( 104 ) in which a cupping insert ( 106 ) for receiving the shaft ( 11 ′) of the pre-compressed bolt ( 10 ′) in the axial direction of the opening ( 104 ) is movably arranged and which widens upwards in a conical manner and in which there can be moved upwards after the final compression operation the jaws ( 112 ) which have at the outer sides thereof chamfered portions which correspond to the conical widening ( 110 ) and by means of which they can automatically close around the head ( 12 ) of the bolt ( 10 ) during the final compression operation owing to the downward movement. 
     
     
         8 . Device ( 100 ) according to  claim 7 , characterised in that it comprises a hollow-cylindrical stamp ( 122 ) which is received in a hollow-cylindrical stamp retention member ( 124 ) in an axially displaceable manner, the stamp retention member ( 122 ) being arranged in such a manner that it first presses the jaws ( 112 ) downwards during the final compression operation so that they close around the head ( 12 ) of the bolt ( 10 ) and the stamp ( 122 ) can only then be moved downwards in order to form the bead ( 18 ) as an upper delimitation of the groove ( 20 ) or channel.