| 摘要 |
PROBLEM TO BE SOLVED: To stabilize quality by preventing generation of a crack, simplify machining and reduce the cost thereof, and to reduce pressure fluctuation in a common rail, in a connecting structure for a common rail and an injection pipe assembly and a forming method thereof. SOLUTION: The common rail 1 has a branch hole 13 of an inside diameter of 3.5 mm. A tip portion of a collar 22 of an injection pipe assembly is plastically deformed by a two-stage drawing method that leaves a compressive residual strain to thus form a projecting portion 25 with an outside diameter reduced below the inside diameter of the branch hole and with an inside diameter of an internal through-hole reduced in two stages. The projecting portion 25 is loosely inserted in the branch hole 13. The branch hole 13, because of a large inside diameter, can be easily formed and be protected against a crack to ensure stable quality. An orifice hole, with a reduced diameter, can reduce pressure fluctuation in the common rail. |
