| 摘要 |
PROBLEM TO BE SOLVED: To provide an expansion pipe to be used in constructing a scaffold, in a construction site or the like.SOLUTION: A freely expandable/contractable expansion pipe (6) is constructed by slidably fitting an inner pipe (5) into an outer pipe (4). Bolt means (19) is screwed to nut means (18) fixed on the outer pipe (4) so as to be freely movable back and forth; and is constructed so as to have the tip of the bolt means (19) locked in and fixed to the inner pipe (5). The nut means (18) is constructed as a rectangular discal body (22) comprising an end surface part (20) having first width W1 along the axis direction of the outer pipe (4) and a side surface part (21) having second width W2 along a radial direction of the outer pipe (4). The discal body (22) comprises: a joint surface (23) formed so as to recess the top surface of the discal body (22) in a circular arc-shape in the direction of the second width W2; and vanes (24, 24) which are on both sides of the joint surface (23) and extend in the direction of the second width W2, and whose top surfaces are flat surfaces. A vane (24) and an outer peripheral surface of the outer pipe (4) are welded and fixed to each other through a groove part (27) formed between the vane (24) and the outer peripheral surface by making the joint surface (23) be in contact with a circular arc surface of the outer peripheral surface of the outer pipe (4). |
