| 摘要 |
PURPOSE:To annihilate a defect existing in the vicinity of the surface of a center hole of a hollow rotating cylindrical body, and to prevent the occurrence of fatigue breakdown due to repeated stress, by heating the center hole to a specified temperature, and also pressing it by leading in high-pressure gas. CONSTITUTION:An induction heating coil 5 is inserted into a center hole 6 of a hollow cylindrical body 4 such as a power generator turbine rotor, a rolling roll, etc., and the upper and lower ends of the center hole 6 are tightly sealed up by an upper cover 2 and a lower cover 7. A heating coil 5 is electrically conducted, the surface of the center hole 6 is heated to about 1,000 deg.C, also Ar gas is pressed into the center hole 6 by a pipe 1 passing through the upper cover, and internal pressure is put. The surface temperature is set to 1,200 deg.C, gas pressure is set to 1,500kgf/cm<2>, this state is held for 30min, and after that, a temperature and pressure are gradually dropped and are set to a normal temperature and the atmospheric pressure. In this way, a choked hole existing in the vicinity of the surface of the center hole 6 is entirely annihilated, and it is possible to prevent the occurrence of fatigue breakdown by an operation of repeated stress. |
