PURPOSE: To prevent an operator on the ground from unexpectedly dropping a cylindrical body which is clamped by a clamping part during no manipulation of an elevation control part, by providing a movement inhibiting part for inhibiting the vertical motion of the cylindrical body.
CONSTITUTION: A tool for longitudinally cutting a pipe is advanced so that the front end of a first cylindrical member passed over the lower end of the front end part of a longitudinal pipe 4. The advance of the tool is carried out by an elevating mechanism 20 for the cylindrical body 6. That is, an elevating operating part 22 is manipulated while the cylindrical body 6 is left to be clamped by the clamping part 21, and accordingly the cylindrical body 6 is lowered in response to the manipulation. It is noted that a movement inhibiting member 23 inhibits the cylindrical body 6 clamped by the clamping part 21 from being lowered when an elevation control part 22 is not operated.
KATO KATSUTOSHI
NAKAO TOMOYOSHI
