Patent ID: 7431781
Filing Date: 2008-10-07
Classification: F02M

Abstract:
1. A method for forming a common-rail injection system for a diesel engine, comprising the steps of: providing a main pipe rail formed from a transformation induced plastic strength steel, the main pipe rail having an axially-extending circumferential wall with an inner circumferential surface defining a flow passage through the main pipe rail, a branch hole extending through the axially-extending circumferential wall and communicating with the flow passage; subjecting the main pipe rail to heat treatment sufficiently for converting at least portions of the transformation induced plastic strength steel to austenite; subjecting the inner circumferential surface of the main pipe rail to autofrettage processing for applying an internal pressure and plastically deforming the inner circumferential surface of the main pipe rail for leaving a compression stress on the inner circumferential surface; and applying a pressing force at a location surrounding the branch hole, whereby the autofrettage processing and the application of the pressing force produce process induced martensite at locations on the axial circumferential wall defining the inner circumferential surface and surrounding the branch hole.