| 摘要 |
PURPOSE:To simply measure the hardness of the inner peripheral surface of a center hole having a small diameter with good accuracy, by providing a spiral groove to the center hole of a turbine rotor. CONSTITUTION:The side surface 3 of a spiral groove 2 is formed so as to form an angle of 45 deg. to the axis 5 of a center hole and a hardness detector 4 is arranged to the side surface 3 in the direction vertical to said surface 3. The detector 4 is connected to a hardness meter operating apparatus 9 while the apparatus 9 is arranged to the center hole through wheels 10 to be connected to a controller by a cable 1. The apparatus 9 is inserted in the center hole from the inlet thereof and advances to the axis direction of the center hole while rotates by the wheels 10. The wheels 10 are driven by a servo motor and stopped when the apparatus 9 reach a predetermined position having to measure hardness to perform the measurement of hardness. Further, during the movement of the apparatus, the detector 4 is drawn up to the direction shown by an arrow 15 and not brought into contact with the side surface 3 but pressed to the direction shown by an arrow 16 and fixed at the time of measurement to be fixed. Subsequently, the impact body in the detector 4 collides with the side surface and the ratio of a repulsive speed is measured to make it possible to measure a hardness value with good accuracy.
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