Process Stability in the Tube Hydroforming Process

Material properties have a significant influence on the process stability in tube hydroforming, particularly in series production. Mainly tubular material with longitudinally oriented welding lines is used in tube hydroforming. A new test method was developed to examine the important properties of the semi-finished product, such as flow pressure or maximum circumferential elongation during the hydroforming process. Knowing these parameters, the process control can be adjusted according to the differences of the varying semi-finished product charges. Another option to improve the process stability is a new process control strategy, which uses the volume flow instead of the conventionally used pressure as control variable. A volume control enables the production of sound parts made of different materials with varying wall thicknesses without changing the process control settings.