Seamless tube prodn. - using long mandrel advancing together with tube at thirty per-cent of tube advancing speed

摘要

The rolling mill has six rolling stands followed by a smooth finishing stand. The mandrel rod fitted with mandrel is introduced into the first rolling stand and is kept in place and controlled by control devices. The control devices feed the mandrel rod together with the mandrel in the same direction as the tube. When the front end of tube reaches the entrance to the second rolling stand, the velocity of the mandrel advance is increased to a value slightly less than the operating speed.