Advanced Manufacturing of Torsionally Flexible Vacuum Bellows

Metal bellows are thin-walled cylindrical components with a corrugated structure perpendicular to the cylinder axis. Bellows are used in numerous applications requiring flexible connections between vessels which must be sealed in a pressure-, temperature- and media-resistant manner. Conventional bellows geometries are highly flexible during axial, lateral and angular motion, but generally do not allow for rotational flexibility, i.e., torsion. As such, bellows users requiring rotation are often required to add expensive, custom in-vacuum motion systems to meet their alignment and/or processing needs. In this Technology Transfer Opportunity (TTO), RadiaBeam Technologies will partner with Argonne National Lab (ANL) to industrialize and market a torsionally flexible UHV bellows. The design is based on a 2020 ANL patent which incorporates hollow, re-entrant shoulders helically wound around a central bore, meant to uniformly distribute the torsionally stress. While this geometry would be extremely difficult to manufacture using conventional methods, it is perfectly suited for Additive Manufacturing, otherwise known as 3D printing. In Phase I, we demonstrated the capability to design, fabricate and characterize torsionally flexible electroformed bellows, providing a clear understanding of the development strategy needed to commercialize this innovating manufacturing sequence. We designed and printed a parametric bellows design focusing on 2 main process related challenges: roughness and plating uniformity. The aluminum mandrels were then polished, cleaned and plated using an external vendor. The mandrels were then chemically dissolved, leaving behind a thin-walled electroformed part. The parts were microscopically inspected and mechanically tested. The vacuum and joining properties of the thin-walled electroform was also investigated. The primary focus of Phase II will be to iterate and optimize the design-fabrication-testing described above. We will conduct comprehensive vacuum and mechanical tests to determine mechanical limits and reliability. We will also work with leading 3D printing machine manufacturers to limit surface roughness of the necessary downward facing surfaces. We will also develop custom plating tooling to normalize the thickness uniformity. At the conclusion of this project, we anticipate having a unique bellows product with a detailed manufacturing sequence and well-characterized properties (dimensional stability, cleanliness, service life, etc). Bellows are used whenever components must retain some flexibility while also sealing in a pressure-, temperature- and media-resistant manner. Current bellows only allow for lateral, angular and axial displacement; torsional displacement is not possible. We aim to qualify and commercialize a torsionally flexible bellows design invented by Argonne National Lab. These bellows can be used to simplify the installation and alignment of vacuum systems, a key labor consideration for next generation accelerators. Furthermore, torsionally flexible bellows can be used for other vacuum-related process (analytical instrumentation, semiconductor production, etc). With further market research and product development, our first- of-its-kind product can be expanded to other markets including medical and energy.