| 摘要 |
PROBLEM TO BE SOLVED: To provide a method of machining internal threads of a pipe in high efficiency in producing the pipe at low cost. SOLUTION: The method and equipment comprises a heating means which beforehand heats the pipe P at a designated temperature, a cylinder 1 which has a through hole 1c for supplying pressurized fluid at at least one end thereof in the lengthy direction and a detachable end wall 1a, pushing pistons 2, 3 used as metal dies for holding both ends of the pipe P and which are slidably disposed in the cylinder in the axial direction, an intermediate metal dies 5 which are separately disposed inside the cylinder slidably in the axial direction along the root inside the thread which is formed to an internal thread shape 4 at a compression state, and a pressurizing means which exerts fluid pressure inside the pipe P inserted and set in between the pushing pistons 2, 3 used as metal dies for the pipe ends and the intermediate dies 5.
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