PURPOSE: To make the temperature distribution in the longitudinal direction of a mandrel bar uniform and to manufacture a seamless pipe having the uniform wall-thickness distribution in its longitudinal direction, by measuring the temperature distribution in the longitudinal direction of the mandrel bar, after being used for rolling a seamless pipe, and cooling it by regulating the distribution of cooling water flow rates basing on the measured results.
CONSTITUTION: A mandrel bar 3 after finishing the rolling of a seamless pipe (shell), is transported to a cooling means 4 along a return line 2, and the temperatures in the longitudinal direction of the bar 3 are measured on the way of transportation by a thermometer 9. The measured values are inputted to a cooling controllng circuit 6 to calculate the distribution of cooling water flow rates so as to make the temperature distribution in the longitudinal direction of the bar 3 uniform. The openings of flow regulating valves 4b of nozzles 5 arranged at plural parts in the longitudinal direction of the bar 3 are regulated basing on the calculated values, to cool the bar 3 to the uniform temperature in its longitudinal direction. When a new shell is rolled by using this mandrel 3, a shell having the uniform wall-thickness distribution in its longitudinal direction is obtained.
KOMINE ISAMU
YOSHIDA MASATO
FUSHIMI NAOYA
AKITA SHINJI
TANAKA MEGUMI
HATANAKA MASAYUKI
