Investigation of roll forming process and quality control factors for metal bipolar plates

• Published in: International journal of hydrogen energy 2024-12, Vol.93, p.898-909
• Main Authors: Zhang, Jie, Chen, Zhiqiang, Zhang, Han, Zeng, Yun, Zhang, Xuwei
• Format: Article
• Language: English
• Subjects: Filling ratio; Metal bipolar plate; PEMFCs; Roll forming; Stainless steel; Thinning ratio
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.10.433

Metal bipolar plates (BPPs) are crucial components of proton exchange membrane fuel cells (PEMFCs), with the quality of their formation affects the power generation efficiency and lifespan of the fuel cells. The predominant manufacturing method, stamping, often results in localized excessive stretching of metal BPPs, thereby limiting the depth of the flow channels. Roll forming, dominated by bending deformation, is a forming process that ensures uniform thinning and greater depth of BPPs. The multi-directional flow channel roll forming model for BPPs is constructed in this paper for the first time, the characteristics of the roll forming process is investigated. Effects of process parameters on the forming results are discussed. The investigation indicates that during the roll forming process, the channel ports and corners are critical areas where defects are most likely to occur. The average filling ratio of the longitudinal flow channels is 5.6% higher than that of the transverse flow channels. The plastic strain in the longitudinal flow channels is about 36% higher than in the transverse ones, which making the form is more difficult to form, but the thickness is more uniform. Increasing the diameter of the rollers can enhance the filling ratio and flatness, but it will exacerbate thinning at the corners of the flow channels. When the ratio of the flow channel width to the rib width is close to 1, the filling ratio of the BPP is higher, with less thinning, resulting in a better forming result. As the depth of the flow channel increases, resulting in a thinner BPP, when depth-to-width ratio exceeding 0.6 is more likely to lead to failure. Increasing the speed of roll forming can lead to a greater thinning of the BPP and may even cause it to crack. The thinner the sheet metal is, the higher the filling ratio of the BPP and the more uniform its thickness. Those results can provide technical references for the structural design and forming process optimization of BPPs. [Display omitted] •Roll forming of bipolar plate with multi-direction continuous flow channels was studied for first time.•The port and corner of the flow channel roll forming are easy to failure.•The maximum depth to width ratio of roll forming of stainless-steel bipolar plate is 0.6.•Filling ratio of longitudinal channel is 5.6% greater, and plastic strain is 36% higher than transverse channel.•Roll forming effect is the best when channel width ratio is close to 1.