THICKENING METHOD OF METALLIC PIPE

摘要

PROBLEM TO BE SOLVED: To facilitate die drawing work after executing thickening in a state that a die is inserted into the inside of a metallic pipe. SOLUTION: A taper is provided in the outer surface of a die 10 along the longitudinal direction of a metallic pipe 1. When the die is drawn after a thick wall part 1A is formed in the outside of the die 10 by the thickening of the metallic pipe 1, the die 10 is drawn toward the side wherein its outside diameter is larger. Thus, since a gap is produced between the thick wall part and the die, the die is easily drawn with small force without damaging the inner surface of the thick wall part.