PURPOSE: To elevate a punch member while rotating the same, reduce a residual stress in the radial direction causing in the branching seat of a work, eliminate return phenomenon due to spring back and form a high precision branching seat for the improvement of quality, in a burring device for working a branching seat which constitutes the connecting part of a work to be used for metallic tube manufacturing such as for a faucet casing.
CONSTITUTION: In a burring device by which a burring is performed on the prepared hole of a work with dies 1, 2 and the punch member 16 of a punching holder 10, a thread part 11 is provided on the punch holder 10 directly under the prepared hole, the punch member 16 is screwed in this thread part 11, elevating while rotating, and a burring is performed on the prepared hole.
NAKAMURA KATSUAKI
OOKUBO TSUGIYA
YUBISUI AKIRA
YANAGIDA TAKAYOSHI
MATSUO YUJI
