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Abstract：Vacuum Vessel is the main component of CFETR (China Fusion Engineering Test Reactor), a series of theoretical studies and engineering verifications should be done from the period of Vacuum Vessel structure design to analysis optimization, from manufacture and assembly process to the plasma experiment study. Notably, shells forming is relatively in the earliest phase, also one of the most important processes during Vacuum Vessel manufacturing. The profile errors caused by spring-back of shells at room temperature will directly influence the subsequent manufacturing techniques and experiment studies, so a set of dies whose profiles can be revised have been designed based on the spring-back theory. Differently from the regular casting press forming mold, the set of dies consist of surface plate and a framework structure of which the assembly and disassembly is easy to made according to the forming dimensional quality. Firstly, the empirical formula has been used to calculate the theoretical die profile value which is mostly determined by the mechanical properties of 316LN. Then, choosing three relevant nearby values to simulate the forming process in which the optimal profile errors of shell must meet the demand of ±2mm, Finally, the optimal dimensional value of the molds have been confirmed to guide the forming experiment study. After experiments, the actual profile errors, thickness reduction, maximum spring back, maximum deformation and surface residual stress have been measured. And those data are an accurate indicator of what from the FEA, verifying the reasonability of the manufacture process which can be used to guide the forming of the whole D shape shells.
Key Words: CFETR Vacuum Vessel, Forming Process, Molds Design, Spring-back, Residual Stress
| Eligible for student paper award? | No |
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