PIPE MEMBER AND METHOD OF MANUFACTURING THE SAME

PROBLEM TO BE SOLVED: To provide a pipe member formed by integrating a small-diameter metal pipe and a large-diameter metal pipe via a double pipe structure part. SOLUTION: A diameter expanding punch 12 is press-fitted into the small-diameter pipe 3 through the large-diameter pipe 2, thereby integrally expanding the diameter of the small-diameter pipe 3 and the large-diameter pipe 2. As the diameter of the small-diameter pipe 3 is expanded, the axial length of an expanded part 3b is shortened, and the tip end of the expanded part 3b of the small-diameter pipe 3 is separated apart from a step part 2c of the large-diameter pipe 2. In this state, the large-diameter pipe 2 and the small-diameter pipe 3 are displaced from each other in the axial direction. In order to avoid this, during molding of an expanded part 2b and the expanded part 3b, a part of the expanded part 2b of the large-diameter pipe 2 is radially inwardly deformed by a pin 11 to form a retaining part 5 which is engaged in the expanded part 3b of the small-diameter pipe 3. COPYRIGHT: (C)2009,JPO&INPIT