METHOD AND DEVICE FOR CONTROLLING SPEED OF TANDEM MILL

PURPOSE:To provide a method and a device for controlling the speed of a tandem mill without giving disturbance of a mass flow balance to variation of a plate thickness and a forward slip under rolling. CONSTITUTION:An output of a speed setter (MRH) 10 setting a reference speed of the tandem mill is defined as a plate speed V5D on the outlet side of a 5-th stand, an outlet side plate speed V1D-V4D at each stand is obtd. by mass flow computing elements 21-24 for calculating mass flows after and before the stand by using measured values of the plate thickness measured by this V5D and an actual plate thickness value measured by a plate thickness detecting device on the outlet side of each stand. Then, each of speed command values V1-V5 at each stand is obtd. by a outlet side speed V1D-V5D of each of these stands and forward slip computing elements 41-45. In this way, since a stable rolling can be carried out without disturbing mass flow balance irrespective of variation of the plate thickness and forward slip in actual rolling, the accuracy of plate thickness of a product can be improved.