Method and device for producing hardened steel components

Abstract

The invention relates to a method for press hardening sheet steel components in which a blank is detached from a sheet steel band composed of a hardenable steel alloy and the blank is then austenitized, in that it is heated to a temperature greater than Ac3 and is then inserted into a forming tool and formed in the forming tool, and during the forming, is cooled at a speed greater than the critical hardening speed, characterized in that in order to inhibit microcracks of the second type from being produced during the forming and hardening process in the sheet metal blanks that are to be formed, oxygen is supplied adjacent to the positive radii and/or drawing edges; the invention also relates to a device for performing this method.

1 . A method for press hardening sheet steel components in which a blank is detached from a sheet steel band composed of a hardenable steel alloy and the blank is then austenitized, the method comprising: heating the blank to a temperature greater than Ac 3 ; inserting the blank into a forming tool; and forming the blank in the forming tool, wherein during the forming, the blank is cooled at a speed greater than the critical hardening speed, characterized in that in order to avoid microcracks of second type from forming in the sheet metal blank to be formed during the forming and a hardening process, the ambient medium is injected into or aspirated from points that are subjected to tensile strain. 
     
     
         2 . The method according to  claim 1 , characterized in that the injection of the ambient medium takes place with more than 1 bar of positive pressure. 
     
     
         3 . The method according to  claim 1 , characterized in that the ambient medium is air or oxygen or nitrogen. 
     
     
         4 . The method according to  claim 1 , characterized in that the ambient medium is injected or aspirated continuously. 
     
     
         5 . A device for performing the method according to  claim 1 , having two forming tool halves; the two forming tool halves cooperate in order to deep-draw a blank and are embodied so that they can move toward and away from each other; and at least one supply line or drain line ( 8 ) for exchanging a fluid medium at points that are subjected to tensile strain. 
     
     
         6 . The device according to  claim 5 , characterized in that, at least one recess is provided in a region of the sheet metal that is subjected to tensile strain. 
     
     
         7 . The device according to  claim 6 , having a plurality of recesses and characterized in that the recesses ( 5 ,  6 ,  7 ) and/or tool surfaces ( 3 ,  4 ,  10 ) are supplied from the rear, i.e. from the tool ( 1 ) side, with an oxygen-containing fluid by means of supply openings and correspondingly drilled lines ( 8 ).