Patent ID: 7213576
Filing Date: 2007-05-08
Classification: B21K,F02M

Abstract:
1. A high pressure fuel injection tube which is a high pressure fuel injection tube comprising a connection head portion comprising a seat face in a spherical shape, a ring-like flange portion arranged to be formed to be spaced apart from the seat face at an interval therebetween in an axis core direction, and a conical portion conversingly formed in a direction of the seat face at the interval region reaching a position of the ring-like flange portion continuously from the seat face at a connection end portion of a thick-walled steel tube having a comparatively slender diameter, wherein by providing an undercut bent recess groove in a ring-like shape having a deep depth at a portion of the conical portion, a ring-like recess groove on an inner side of the head portion produced in accordance with forming the connection head portion is formed into a contour shape of a section which is provided with a shallow depth and is smooth and a compressive residual stress is made to be present on an inner peripheral face of the ring-like recess groove portion.