Importance

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Abstract

A process for manufacturing a spool valve whereby a plurality of quenching processed collars are fitted to a shaft material so that the collars are arranged at predetermined positions on the shaft material. The collars have respective substantially central holes through which the shaft material extends. The diameter of portions of the shaft material is contracted in a vicinity of both opposite ends of each of the collars by rolling dies so as to cause plastic flow of a metal constituting the shaft material. Pairs of circular convex portions are then formed on outer circumferential faces of the diameter contracted portions of the shaft material. The circular convex portions each have an outer diameter larger than an inner diameter of the substantially central holes of the collars, and the circular convex portions are formed such that side faces thereof are in close contact with respective associated circular concave portions formed at both ends of the collars in a vicinity of the substantially central holes of the collars, whereby the collars are fixed to the shaft material.

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First Claim