Method and pressing tool for producing a complex formed sheet metal part with great drawing depth

A method for producing a complex sheet metal part said method comprising:

• inserting a metal sheet into an open pressing tool, said pressing tool comprising a lower tool part which includes a punch, a downholder surrounding the punch and multiple punch inserts, and an upper tool part which includes a die and a die ring surrounding the die;
• closing the pressing tool by moving the upper tool part downwards thereby clamping a border region of the metal sheet between the die ring and the downholder;
• with the punch inserts being in an extended position, moving the upper tool part further downwards so that the die ring displaces the downholder downwards and the metal sheet is pulled over the extended punch inserts, thereby generating local material reserves of the metal sheet;
• forming a first region of the metal sheet between the die ring and the punch by moving the upper tool part further downwards into a position in which the die ring and the downholder have reached respective lower movement dead points, wherein during the moving of the upper tool part into said position the punch inserts are actively retracted, thereby releasing the local material reserves;
• and
• forming a second region of the metal sheet between the die and the punch by moving the die further downwards until the die reaches a lower movement dead point,
• wherein during the forming of the second region a peripheral region of the metal sheet is clamped between the die ring and the downholder and between the die ring and the punch so as to prevent flow of metal sheet material from the border region of the metal sheet so that only the local material reserves are used for the forming of the second region,
• wherein the punch inserts are actively retracted by a mechanical coupling configured as catches with the downholder,
• wherein the punch inserts are fastened on a frame moved along by the catches arranged on the downholder.