VERFAHREN UND VORRICHTUNG ZUM BILDEN EINES DURCH EINEN KRAGEN UMGEBENEN LOCHES IN EINER METALLENEN PLATTE ODER IN DER WAND EINES METALLENEN ROHRES DURCH REIBUNGSWAERME UND DRUCK

摘要

A method of and an apparatus for forming by frictional heat and pressure a bossed hole in a metal plate or a tube wall with the aid of a rapidly rotating piercing tool, of which the axial feed is controlled, in such a manner, that during a predetermined time from the point of time, at which the tool comes into contact with the plate or tube wall the axial movement of the tool is slower and after that time said movement is faster than a movement of given speed.