PURPOSE: To relax concentration of stress in welding start/finish end parts of a vane, crown and a band by thinning a plate thickness the crown and the band only in the periphery of a joint part as compared with a plate thickness of the crown and the band not in a connecting part, so as to decrease rigidity of the connecting part.
CONSTITUTION: A water turbine runner is manufactured by welding a vane 1, crown 2 and a band 3. Here a plate thickness of the crown 2 and the band 3 corresponding to a T-shaped joint flange side, positioned in respective connecting parts of welding start/finish end parts of the vane 1, is thinned as compared with a plate thickness of the crown 2 and the band 3, not in the connecting part, only by the periphery of a joint part. A worked part in the outside of the crown 2 and the band 3 is applied with smooth cutting work, so as to prevent new stress concentration from being generated in the worked part. Thus by relaxing stress concentration in the welding start/finish end parts of the vane 1, crown 2 and the band 3 relatively easily cracked, strength in the welding joint part can be increased.
ENOMOTO KUNIO
HAYASHI MAKOTO
SAKATA SHINJI
