| 摘要 |
PURPOSE:To minimize the shrinkage and deformation caused by shrinkage at end sections of a pipe, by inserting under pressure press-in plugs respectively held by holder sections into both end sections of the pipe and bending the pipe by using upper and lower dies. CONSTITUTION:A straight pipe 11 is put on a lower die and pipe placing bases 19 and 19 and holder driving mechanisms 26 are actuated. Then both holders and press-in plugs advance towards both end sections 11a of the pipe 11 under united conditions and the press-in plugs 51 are inserted under pressure into the end sections 11a. Thereafter, clamps 20 and 22 are lowered and the pipe 11 is clamped and an intermediate upper die 12 and side upper dies 13 and 13 are lowered under an incorporated condition and bending of the pipe 11 is performed. Since the press-in plugs 51 are inserted under pressure into the end sections 11a, the cross-sectional shape of the pipe 11 near the end sections 11a is hardly deformed at the time of bending. After a hole is installed to the pipe 11 by means of a piercing punch 14b, the holders 42 are retreated and the press-in plugs 51 are removed from the end sections 11a, and then, cutters 18 are lowered and the end sections 11a are cut off.
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