| 摘要 |
PROBLEM TO BE SOLVED: To increase internal pressure fatigue strength by applying a pressing force in the axial direction of a boss part so as to protrude the flow passage opening end part of a branch hole and providing the branch hole formed to have a complete round inner peripheral surface by eliminating a projecting part. SOLUTION: By means of a pressing force from a punch 2, the inner peripheral surface of a high pressure fluid member flow passage 1-1 is made slightly flat. When the pressing force is applied, plastic deformed and elastic deformed parts are formed. In a finishing process, a part 1-9 protruded inward and made lightly flat by the application of the pressing force from the punch 2 is eliminated by machining or the like to form a complete round inner peripheral surface. Then, in a boss part 1-4, a branch hole 1-2 is formed to have a circular peripheral surface communicated with the flow passage 1-1 of a high pressure fluid member 1 and communicated with a flow passage as a pressure receiving sent surface 1-3. A female screw 1-7 is machined in the inner peripheral surface of the bottomed hole 1-5 of the boss part. Thus, since an internal pressure fatigue strength is increased in the branch hole, fluid leakage can be eliminated. |
