Hitachi Astemo Ltd.

Yuki Sugiyama

Masato Higuma

Ryohei Matsutake

Yuta Yanagisawa

Kenichi Gunji

An object of the present invention is to provide a working method of an orifice, which has excellent working accuracy and high productivity in order to work an inclination portion (tapered portion) on the entire circumference of an inner wall of an orifice. Therefore, a working method of an orifice includes a first step of forming an orifice holein an orifice forming member, a second step of pressing a downstream end surface of the orifice forming member in which the orifice holeopens, in a direction toward an upstream side of the orifice holeby a punchhaving a cutting blade portionlarger than a cross section of the orifice hole. The second step causes a material of the orifice forming member to flow from an entire circumference at the downstream end portion of the orifice holeto an inside of the orifice holeto form a cross-sectional area reduction portionin which a cross-sectional area of the orifice holeis reduced from an upstream side to a downstream side.

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Hitachinaka, Japan

Yuki Sugiyama