| 摘要 |
PROBLEM TO BE SOLVED: To work a tube which has a cylindrical part which is larger than the diameter of the tube in the end part of the tube and off-centered and has a taper part between the cylindrical part and the unworked part without generating buckling with a punch. SOLUTION: When the outside diameter of the cylindrical part is expressed by (d), deviation between the axial center of the cylindrical part and the axial center of the tube by eccentricityδ, the part of the tube near to the part to become the cylindrical part is held with a die and worked into the outside diameter of (d-26δ) mm which is co-axial with the tube and, thereafter, after arranging the die one side of which is abutted on the part to become the cylindrical part with a line, the other side has a space and the taper part is abutted, the outside diameter is worked to (d) mm and the eccentric shape in which the ratio of the eccentricity to the outside diameter of the tube is >=0.1 is obtained.
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