No abstract

Metallic bipolar plates (BPPs) are key components in the proton-exchange membrane fuel cell (PEMFC), which can replace traditional fossil fuels as a kind of clean energy. However, these kinds of plates, characterized by micro-channels with a high ratio between depth and width, are difficult to fabricate with an ultra-thin metallic sheet. Then, ultrasonic-vibration-assisted stamping is performed considering the acoustic softening effect. Additionally, the influence of various vibration parameters on the forming quality is analyzed. The experimental results show that ultrasonic vibration can obviously increase the channel depth. Among the vibration parameters, the vibration power has the maximum influence on the depth, the vibration interval time is the second, and the vibration duration time is the last. In addition, the rolling direction will affect the channel depth. When the micro-channels are parallel to the rolling direction, the depth of a micro-channel is the largest. This means that the developed ultrasonic-vibration-assisted stamping process is helpful for improving the forming limitation of micro-channels used for the bipolar plates in PEMFC.

No abstract

To reduce the weight and volume, and extend the life of the proton-exchange membrane fuel cell (PEMFC) which is considered as a kind of near zero emission green energy, titanium ultra-thin sheet is selected to fabricate the core components- bipolar plates for its smaller density and high corrosion resistance. In order to break through the bottlenecks in the manufacture of micro channels with big ratio of depth and width, a kind of three-stage stamping was investigated for its characters such as high productivity and low cost, etc. FE simulation and optimization of three-stage stamping was carried out considering the reduction of thickness by analyzing the effect of the radius of punch and female die corner, punch displacement and ratio of rib and channel width, etc. Then, the mold was designed, and experiments were performed using a servo drive machine. The arc design of punch end in the first stage can decrease the reduction of thickness from 47–22%. The best ratio between rib and channel width is 0.4–0.6, and radius of final channel corner is 0.15mm. Experimental results of three-stage stamping show that the max. reduction of thickness is about 24%, which is similar with that obtained from FE simulation. Microstructure with uniform small grain size and high surface quality are both helpful for improving the properties of bipolar plates required by PEMFC. This means that the developed three-stage stamping process is very suitable for massive manufacturing the bipolar plates with titanium ultra-thin sheet.