Investigation and optimization of the ultra-thin metallic bipolar plate multi-stage forming for proton exchange membrane fuel cell

Multi-stage forming of the ultra-thin metallic sheets is a promising process for manufacturing fine width and high aspect ratio bipolar plates in proton exchange membrane fuel cell. Correlations between the processing parameters and the channel quality evaluation indicators are investigated experimentally and numerically. A novel parameter optimization method and stage number design guidance are established with the consideration of the indicator priorities and material properties. The forming depth can be increased by larger Stage II punch stroke along with smaller clearance and radius. Increasing or decreasing the Stage II punch stroke and radius simultaneously contributes to larger draft angle. Small Stage II punch stroke and radius are beneficial to greater rib width. More uniform thickness distribution can be achieved by using smaller Stage II punch stroke and clearance. Two-stage forming is enough for soft materials and three-stage forming is suitable for relatively hard materials. Both the output power density and voltage distribution uniformity of the proton exchange membrane fuel cell are improved by employing multi-sage formed bipolar plates. The relationship between the parameters and indicators, optimization method, stage number design guidelines, all serve as the design principles of the micro channel's multi-stage forming for bipolar plates with ultra-thin metallic sheets.