PURPOSE: To enable rolling at different tube expanding rate with out changing a guide shoe and with a same-shaped shoe by inclining the shoe to the rolling direction of the tube in accordance with the target tube expanding rate.
CONSTITUTION: At the time of rolling at large tube expanding rate using the same guide shoe 84, rolling is executed without inclining the shoe 84 (or slightly inclining the shoe) at its larger face angle αs2 on the outlet side (or larger apparent face angle αs2' on the outlet side). At the time of rolling at small tube expanding rate, rolling is executed by inclining the shoe 84 by an inclining angle and making the apparent face angle αs2' smaller as (αs2-). Of course, at the time of rolling at small tube expanding rate, rolling may be executed by using a guide shoe having small face angle αs2 on the outlet side without inclining the shoe. In this way, even when the guide shoe is a fixed guide shoe 84 having one kind of face angle αs2 on the outlet side, the apparent face angle αs2' on the outlet side is set in the optimum range by adjusting the inclining angle and the generation of defective biting, defective rear passing-out and hollow breaking are prevented.
YORIFUJI AKIRA
TOYOOKA TAKAAKI
