PURPOSE: To enhance the workability and mass-productivity for the press burring of a metallic tube and improve the working accuracy.
CONSTITUTION: A prepared hole 3 is opened at a specific position of a tube 1, and a burring tool 20 consisting of a punch member 21 is positioned inside the tube 1 corresponding to the prepared hole 3. This punch member 21 is linearly moved outside from inside the tube 1, the circumferential edge part 3a of the prepared hole 3 is bent up outward by the raising working part 22 of the punch member 21, and the raised opening part 2 is worked for raising. Continuously after this raising working, a drawing is applied on the inside circumferential surface of the raised base part 2a of the raised opening part 2 by means of the drawing working part 23 of the punch member 21.
NAKAMURA KATSUAKI
OOKUBO TSUGIYA
YUBISUI AKIRA
YANAGIDA TAKAYOSHI
KATAHIRA HIROMI
