Hollow stamping rolls: the new system revolutionizes the production of bipolar plates
研究新闻 / April 02， 2024
For example, climate-friendly fuel cell systems designed to power the vehicles of the future are still rare and expensive. This is due, among other things, to the complex and expensive production of bipolar plates, which are key components of electrolyzers and fuel cells required by many hydrogen systems. The Fraunhofer Institute for Machine Tool and Forming Technology (IWU) is now taking an important step towards reducing costs and mass-producing bipolar plates with a new hollow stamping and rolling system: the BPPflexRoll. From April 22 to 26, Fraunhofer researchers will be presenting a component of the system at the Hannover Messe 2024 at the Fraunhofer joint booth in Hall 2, Booth B24.
© Fraunhofer IWU
Use the BPPflexRoll to hollow emboss the bipolar plates. In the newly developed technology, the structure of the bipolar plate is formed by a pair of rollers.
© Fraunhofer IWU
The main advantages of this process are the high processing speed, which allows for a significant increase in unit output, economies of scale, and ultimately a significant reduction in costs.
Hydrogen fuel cells have a high efficiency. For example, they use hydrogen and oxygen to generate electricity and use it to power eco-friendly vehicles. Electrolyzers can reverse this process. They use electricity to split water into hydrogen and oxygen. Bipolar plates (BPPs) are required for both hydrogen systems to enclose the conversion components MEA (membrane electrode unit in a fuel cell system) and CCM (catalyst coated membrane, in an electrolyzer). In fuel cell stacks, the bipolar plate's double-wall design allows oxygen and hydrogen to flow to both sides of the MEA and water cool the stack. The problem is that the current expensive production of bipolar plates hinders the application of hydrogen technology and, therefore, the widespread and cost-effective use of hydrogen-powered fuel cell vehicles, for example. This potential can only be exploited through more cost-effective mass production of core components. Researchers at the Fraunhofer IWU in Chemnitz have now developed a prototype system for hollow stamping rolling together with Profiroll Technologies GmbH. The line is currently in operation at Fraunhofer IWU. It already has control technology and operating concepts that correspond to industrial plants in basic respects. The device consists of three rolling racks with an installation area of 4500 mm x 3300 mm.
Continuous processes replace discontinuous mass production
One of the reasons for the high cost of metal BPP is the discontinuous mass production. "The bipolar plate consists of two stainless steel halves that emboss the gas flow and heat dissipation structure in a discontinuous molding process and then join them. Our hollow stamping and rolling process has the potential to replace these discontinuous process chains or production steps with continuous processes that do not require process interruptions, enabling high-volume outputs, explains Stefan Polster, head of the Sheet Metal Fabrication and Tool Design group at Fraunhofer IWU. One advantage of hollow stamping rolling is the higher processing speed. Up to 120 BPP halves can be produced per minute," confirms Robin Kurth, Team Leader of the Fraunhofer IWU forming machine. By changing the manufacturing process, the researchers hope to halve the manufacturing cost of BPP.
Using a newly developed technology, the structure of the bipolar plates is shaped with the help of a pair of rollers, and a thin metal strip of wafer sandwiched between them runs continuously. One forming roll is defined as a punch and the other as a die. Since almost only one line of rollers used to form the runner is in contact with the workpiece, the process force can be reduced by an average of 10 times compared to conventional hollow stamping. This has led to smaller, more cost-effective plant technology. Another advantage of the system is its flexibility: the number of roller banks required can be individually adjusted according to the geometry of the bipolar plates.
Cognitive molding machine with integrated monitoring system
With the new test facility, Fraunhofer IWU's researchers are also taking an important step towards cognitive molding machines that can be self-monitoring and controlled using sensors and intelligent algorithms. "Compared to the previous system, we will be able to check the quality of BPP in future runs by recording process parameters with sensors, merging them and analyzing them in a relevant way," says Robin Kurth. The data is then processed and made available through a cloud solution. The first bipolar plates produced using this system have already been tested in fuel cells at ISE at the Fraunhofer Institute for Solar Energy Systems in Freiburg.
With BPPflexRoll, researchers are paving the way for the mass production of efficient and cost-effective bipolar plates. At the Hannover Messe from 22 to 26 April, they will be presenting system components with rollers and BPP at the joint booth B24 in Fraunhofer's Hall 2.
本文翻译来自原文2024 I Hollow Stamping Rolls: New System Revolutionizes the Production of Bipolar Plates - Fraunhofer IWU