In order to reduce the effects of the forced vibration caused by inside and outside disturbing forces of machine tool on the quality of thread and the life of extrusion tap, this paper researched the vibration signals in the cold extrusion process of high-strength-steel internal thread under different extrusion conditions, and the change reason was also analyzed through the spectrum analysis. The results show that the variation trend of the vibration amplitude values is similar under different extrusion velocities,

and the master oscillation frequency changes in a random way.The amplitude value of vibration and the master oscillation frequency remain virtually unchanged under different lubrication patterns. While the viscosity number of lubricant exceedes 32mm2/s,the amplitude value of vibration and the master oscillation frequency can change dramatically,and high frequency vibration appears,then causing rupture of the extrusion tap. ª¥