PURPOSE: To shorten the heating up and cooling of a roll without a risk in the roll pipe by keeping temperatures of the internal peripheral surface of the roll and the external peripheral surface of the roll substantially the same in a heating up and a cooling processes.
CONSTITUTION: The temperatures of the internal peripheral surface of a hollow roll 3 and the external peripheral surface of the hollow roll 3 are detected with sensors 8 and 9 and the detected temperatures are sent to a control and adjusting means 20 when heating and cooling a pressure fluid filling a space 6 between the hollow roll 3 and a cross-head 2. The control and adjusting means 20 controls a heating and cooling means 15 to heat and cool the external peripheral surface of the hollow roll 3. A heating and cooling device for the pressure fluid in the space 6 is controlled to keep temperatures of the internal peripheral surface of the hollow roll 3 and the external peripheral surface of the hollow roll 3 substantially the same during the heating up and cooling processes of the hollow roll 3.
BERUNHARUTO BURENDERU
BERUNHARUTO FUNGAA
