| 摘要 |
PURPOSE:To enable a rotary type servo valve to be accurately machined with no generation of unevenness of right and left unbalancing amounts or the like in a port tilt surface for a land part by applying heat treatment to the peripheral part of a cylindrical metal material thereafter grinding this metal material. CONSTITUTION:A cylindrical metal material 1, being used as the original material, applies heat treatment to its peripheral part 10a. Subsequently, this heat treated cylindrical metal material 1a is held being able to rotate with its center axis serving as the rotary shaft to a grinding device. Thereafter, this grinding device grinds the peripheral part 10a of this metal material 1a, further the metal material 1a from this peripheral part 10a to its radial and circumferential directions in accordance with a grinding program, in this way, forming a land part 10b of a servo valve 1b and its grooved part while a top surface 100b in this land part, port tilt surfaces 101b extending to both sides of the top surface and a grooved part 11b between the neighboring port tilt surfaces further grinding a side wall surface 111b of the grooved part and its bottom surface 110b, the desired accurate rotary type servo valve 1b is obtained.
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