US Patent 7854156 Closing device and closing method

A closing device 100 which presses a die 2 against a rotating pipe body 1 such that an open end portion of the pipe body 1 is plastically closed by the die 2 includes a cored bar 3 inserted into the pipe body 1 to close the open end portion of the pipe body 1 on the opposite side of the die 2, and a reactive force applying mechanism 43, 60 which allows the cored bar 3 to retreat and applies a reactive force to the retreating cored bar 3 when the cored bar 3 receives a predetermined load or more during processing of the pipe body 1 by the die 2.