Conical roll-twist-bending process for fabrication of metallic Archimedes spiral blade used in small wind power generator

We propose a novel conical roll-twist-bending (RTB) process to fabricate a metallic Archimedes spiral blade which has variable curvatures on its surface, and it is a key element of a novel wind power generator having a remarkably higher efficiency of about 34% compared with conventional wind power systems. The RTB system consists of a pair of conical rollers (upper and lower sides) and cylindrical twist-bending rollers in the both lateral sides. With the help of forming analysis results, multi-step regional forming method was utilized to fabricate the blade. Also, the process parameters were optimized by a response surface methodology. In this work, we installed the experimental equipment of RTB process, and it was experimentally proven that the developed RTB process was capable of producing a spiral blade with a shape error less than approximately 5%. Furthermore, we believe that the RTB process can be utilized to fabricate diverse sheet metal structures having continuously changing curvatures for various applications.