Active media forming with pressure pulses

Fluid-based forming is excellently suited for producing complex component geometries from tubes, hollow profiles, or sheets. Compared to conventional drawing processes, the tooling effort for this technology is significantly reduced, as one half of the tool set is replaced by the working medium. This medium is typically subjected to hydrostatic pressure during the process, which shapes the workpiece into the remaining half of the tool. This particularly gentle application of force enables very good surface quality while reducing frictional forces. However, forming small radii requires very high working medium pressures and, consequently, complex systems for generation, control, sealing, and clamping, which must absorb very high forces depending on the component size.

This issue can be circumvented by using a short-duration pressure pulse that travels as a wave through the working medium instead of hydrostatic pressure. This pulse can be initiated, for example, by a body impacting the working medium at high speed via a membrane. If necessary, a preforming of the component with moderate hydrostatic pressure can be realized, followed by a pressure pulse for final calibration. This pulse can even be focused on specific areas of the component where particularly high forming pressures are required.

Due to the pressure pulse, the component is formed at very high speed, allowing the typical advantages of high-speed forming, such as an enhanced formability of numerous materials, to be utilized. Currently, the technology of fluid-based high-speed or impulse forming is being researched using the example of forming channel structures from ultra-thin sheets—inspired by typical bipolar plate geometries.

Process advantages:

• Fluid-based forming process with only one tool half adapted to the component geometry
• Gentle force application for excellent surface quality
• Forming of small radii without sealing effort