| 摘要 |
PURPOSE:To reduce and form easily a coiled pipe end part by using a core bar and a press die, forming two lines of bent wrinkles inclined on the outside circumference of a metallic coiled pipe, rotating the coiled pipe as it is, pressing the bent wrinkles, and piling them on the outside circumference of the coiled pipe. CONSTITUTION:A core bar 22 having the outside diameter which is smaller about two times a coiled pipe thickness than the inside diameter of a coiled pipe end part 5 to be reduced is inserted through a metallic coiled pipe end part 5 obtained by forming a projecting line 3', the coiled pipe end part 5 is pressed by a fluid pressure by using a pair of press dies 23, 23' having roughly circular recessed parts 24, 24' whose diameter is a litte larger than the outside diameter of the coiled pipe end part 5, and in a bent wrinkle forming space S formed between the press dies 23, 23', bent wrinkles inclined in the circumferential direction are formed on the outside circumference of the coiled pipe end part 5. Subsequently, the press dies 23, 23' are opened, the coiled pipe is rotated by about 90 deg. in the circumferential direction, said bent wrinkles 27 are pressed by the press dies 23, 23' again and piled on the outside circumference of the coiled pipe end part 5, and the coiled pipe end part 5 is reduced and formed. |
