Patent ID: 7788957

Claim:
An apparatus for sizing a pipe end of a pipe comprising: a plug for sizing the pipe end; a chuck for clamping the pipe; and shifting means for shifting a position of the plug and/or the chuck, characterized by the plug has a circular cross section, and is constituted by a taper portion and a diameter equivalent portion continuously formed from a tip of the plug in succession, an outer diameter of the taper portion gradually expands from the tip toward a rear end while satisfying the following formulas (1) and (2) and the chuck is capable of changing a clamping position of the pipe: 22 ≦LR /( D 1×0.01/2)≦115 (1) R2≧R1 (2) where meanings of respective symbols in the formulas are shown below: D 1 : an outer diameter of the rear end of the taper portion, which also corresponds to an outer diameter (mm) of the diameter equivalent portion, LR: a distance (mm) in an axial direction from the rear end of the taper portion to a position at which the outer diameter of the taper portion is represented by D 1 ×0.99, R 1 : a taper angle (°) at the rear end of the taper portion, and R 2 : a taper angle (°) at the position in which the outer diameter of the taper portion is represented by D 1 ×0.99.