| 摘要 |
PURPOSE:To prevent a foreign matter from remaining within bellows and eliminate the need of after-treatment process by inserting a cylindrical elastic body inside a metal pipe and molding bellows by means of the elastic deformation of said cylindrical elastic body. CONSTITUTION:One end part a1 of an easily deformable metal pipe A is supported by a pipe holder 2. Mold piece 5 having a sectional form corresponding to each meandering section b1 of a bellows B to be molded, are arranged in between the pipe holder 2 and a punch 3. When molding a metal pipe A, a cylindrical elastic body 6 made of urethane rubber, etc. is inserted inside the metal pipe A. When molding bellows, the mold members 5 are placed in a mutually separate condition, and the cylindrical elastic member 6 is inserted inside the metal member A one end of which is supported by the pipe holder 2. Thereby, when the punch 3 is advanced, each part of the pipe wall of the metal pipe A where the mold member 5 does not exist is projected out in the radial direction due to the compression of the cylindrical elastic body 6. After that, as the punch 3 is retracted, the bellows B is completed.
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