Threaded bolt and method for its production

Abstract

A threaded bolt may be produced according to a method including the steps of: forming a cylindrical bolt blank of metal with a root end and a head end, and with a section of the bolt blank adjoining the root end that is reduced in diameter up to a region designed for the formation of lead-in flights. Then, in a first rolling phase, partially form the principal thread flights and the lead-in thread flights using a first pass of flat jaws of a thread rolling machine. Then, in a second rolling phase, fully form the principal flights and the lead-in flights and forming grooves.

1 . A method of producing a threaded bolt, the method comprising:
 forming a cylindrical bolt blank of metal with a root end and a head end such that a section of the bolt blank adjoining the root end is reduced in diameter up to a region designed for the formation of lead-in flights;   partially forming principal flights and the lead-in flights in a first rolling phase using a first pass of flat jaws of a thread rolling machine;   fully forming the principal flights and the lead-in flights and forming grooves in a second rolling phase.   
     
     
         2 . A method according to  claim 1 , wherein the flat jaws comprises a first flat jaw and a second flat jaw;
 wherein the first flat jaw has a rolling profile for the formation of the principal flights and the lead-in flights;   wherein the second flat jaw has an initial section with a thread rolling profile section for the formation of the principal flights and the lead in flights and an end section with ribs for the formation of the grooves.   
     
     
         3 . A method according to  claim 2 , wherein the threaded bolt comprises a shank with a root end and a head end, the shank including a spiral-shaped external thread;
 wherein the external thread includes the principal flights and the lead-in flights, the lead-in flights adjoining the principal flights and being nearer to the root end of the shank than the principal flights;   wherein the lead in flights have lead in surfaces which differ from the principal flight and have a smaller outside diameter than the principal flight.