| 摘要 |
PROBLEM TO BE SOLVED: To ensure the strength of a first engagement part with a base end part of a valve element butted thereto by a structure to press one metal plate for integration, and to prevent wrinkles mistaken for cracks from being formed. SOLUTION: The thickness of a connection part 24 to form a first engagement part 28 is increased by concentrating the material of a metal plate. The strength of the first engagement part 28 is ensured without unnecessarily increasing the thickness of side wall parts 22, 22. Wrinkles are prevented from being formed by forming inclined parts 33, 33 before forming the first engagement part 28 on a curved part 21.
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