Abstract: The F3 stand in a certain CSP hot tandem mill appears strong vibration when thin container strips are rolled. In order to determine its nature and seek measures to restrain the vibration, firstly the F3 internal characteristics of main drive system and stand are calculated, then the main drive system torque, the spindle bending torque and the rollers’ vibration are field tested, lastly the F3 speed spectrum is established. It is found that F3 has weak torsional vibration. The main vibrating energy is concentrated in horizontal (along rolling direction) and vertical direction. And the former is far greater than the latter, but their frequency are both 51 Hz. They are caused by the third order sympathetic vibration of transverse system and first order sympathetic vibration of vertical system excitated by the meshing impact of curved gear coupling. Hereby the corre-sponding measures such as changing curved tooth duly are put forward. In order to eliminate the clearance between work roller’s bearing chock and scaleboard the sheet copper is filled up into the gap. This simple measure is helpful to restrain F3 horizontal vibration and has been employed in some factory.

Key words: CSP tandem mill, Inherent characteristics, Test, Vibration