Abstract: As gear manu facturing is a continuous production process，not only the continuity and efficiency of manu-facturing but also the reliability of forging tools should be guaranteed in the process of precision forging for manufac-turing gears． In this paper，firstly，three tool design schemes respectively with mandrel，without mandrel-hollow billet and without mandrel-solid billet were proposed for the precision forging of hollow cylindrical gears，and the corresponding forming loads were predicted． Secondly，tooth formation，metal flow，tool stress and forming load were analyzed via finite element simulation． Then，the procedures corresponding to the three schemes were de-signed，and a comparison was made between these three precision forging processes and the conventional cutting process in terms of production efficiency and material utilization． Finally，forging trials for hollow cylindrical gears were conducted to verify the validity of finite element simulation and forming load calculation，and the manufactur-ing process without mandrel-solid billet was proved to be the best for the hot precision forging of gears．

Key words: hollow cylindrical gear, gear forging, tool structure, production process, experimental investigation