| 摘要 |
PURPOSE: A press forming method of reducer pipe is provided to form an ordinary pipe into a reducer pipe on the intermediate part of which band protrusion is formed by press working the ordinary pipe. CONSTITUTION: The press forming method of reducer pipe comprises first process of removing welding beads formed on the inner circumference of the pipe by selecting a pipe having diameter corresponding to the large diameter out of small and large diameters of the reducer pipe; second process of cutting the pipe to a length calculated as the total length by taking into account length of the reducer pipe and length of band protrusion to be formed on the intermediate part of the reducer pipe; third process of smoothly processing rough surface of both cut ends of the pipe; fourth process of first clinching the pipe using press so that a semicircular band projection part having a double size compared to width of the band protrusion is formed on the intermediate part of the pipe; fifth process of second clinching the pipe using the press again so that the semicircular band projection part is formed into a certain band protrusion; and sixth process of performing pipe contraction operation on one side part of the pipe using the press so that only half of length of one side part of the pipe is formed into a small diameter, wherein a screw part is formed on the inner circumference of the small diameter of one side part of the pipe.
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