Method of speed control in order to minimize the formation of inner polygons

Process for controlling the tube wall thickness in a multi-structured continuous path reducing mill train having devices for measuring the tube wall thickness comprises keeping the whole path constant by computer-controlled changes of the revolutions of the drive motors and reducing the inner polygon formation to a minimum. Preferred Features: The revolution ratios in a roll stand group are increased by changing the revolutions of the drive motors and are reduced in another roll stand group at the same time so that the path of the tube remains constant.