Device and method for welding half sheets to form a bipolar plate

A method for welding half sheets to form a bipolar plate by way of a device, the method comprising:

• providing an arrangement of half sheets lying on top of one another,
• welding the arrangement of half sheets,
• inserting the half sheets between the lower tool part and a first individual part of a multi-part upper tool part, and
• passing pressurized gas through an at least one first opening in the first individual part, with which the half sheets are pressed against one another,
• simultaneously introducing joining energy for welding the half sheets through at least one second opening located in the first individual part and forming a first portion of weld seams,
• subsequently exchanging the first individual part for at least one second individual part of the multi-part upper tool part,
• passing pressurized gas through the at least one first opening in at least one second individual part, with which the half sheets are pressed against one another, and
• simultaneously introducing joining energy for welding the half sheets through at least one second opening located in the second individual part and forming a further portion of weld seams.