| 摘要 |
The present invention relates to a fixation method between a valve core and a valve shaft capable of preventing the vicinity of a welding part between the valve core and the valve shaft from generating stress corrosion cracking. The valve core is provided with a shaft hole, in an approximate cone shape and with a lower bottom, at the center to fix the metal valve core to the top end of the metal valve shaft. Firstly, the shaft hole of the valve core is nested at the top end portion of the lower bottom; secondly, the shaft end surface of the valve shaft and the lower bottom around are welded; thirdly, the upper portion of the clamp in an approximate cylinder shape is pasted to the periphery of the lower bottom of the valve core, the welding portion and the interface of the welding portion formed through welding are subjected to shot blasting at the inner side of the clamp so as to apply compression stress until the depth is larger than the portion of the pitting depth generated by corrosion. A step portion, lower than the central portion, is formed at the periphery of the lower bottom of the valve core in advance. Besides, when the upper end portion of the clamp is pasted to the periphery of the lower bottom, the upper end portion of the clamp is embedded into the step portion. |
