PURPOSE: To efficiently manufacture a metallic pipe having an eccentric round hole in good dimensional accuracy by using a specific mandrel and a die having eccentricity to the axis of the mandrel and hot-extruding in the condition of fixing the mandrel to an extrusion starting position. ;CONSTITUTION: The die 2 having eccentricity of a passing hole to the axis of the mandrel 4 is set at the front of a container 1 in an extrusion press. Successively, after a heated billet 3 to a prescribed temp. is charged in the container 1, a support-connecting part 7 is made to fix to a mandrel holder 8 so as not to advance the mandrel 4 machined matching a forming part 9 to a prescribed inner diameter size of the product in the extruding direction from the extrusion starting position. Then, a dummy block 6 is advanced with a stem 5 and the extrusion pressure is applied to the billet 3, and billet 3 is extrusion-deformed in the extrusion-forming part formed with the die 2 and the forming part 9 of the mandrel 4 to manufacture the metallic pipe having eccentric round hole in the outer diameter center and the inner diameter center.;COPYRIGHT: (C)1993,JPO&Japio
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