Abstract: The expanding tube connection by pushing through balls with multi-step for hollow assembled camshaft was presented and numerically analysed by finite element simulation. The single-step，double-step and triple-step were contrastive studied from the aspects of press-fit force，residual strain，axial loading force and maximum torsion. Static torsional stregth of the assembled camshaft on expanding tube connection by multi-step pushing through balls were determined experimentally. ．The results show that multi-step tube expanding assembly,with equal amount of interference,can increase in the press-fit force and connecting strength between cam and tube，improve tube expanding conditions and reduce balls load. Static torsion of assembled camshaft by the double or triple-step tube expanding is 12% larger than the single-step one. The new technique of assembled camshaft is suggested for its simple procedure and connecting reliability.

Key words: assembled camshaft , connecting of tube expanding, multi-step tube expanding, numerical simulation