Patent ID: 6758077
Filing Date: 2004-07-06
Classification: B21D,F16F,Y10T

Abstract:
A method of manufacturing a cylinder, comprising:a step of inserting a cored bar into piping material having a reduced inner radius at one end; a step of supporting the reduced radius section of the piping material with an inserted tip of the cored bar; and a step that includes spinning the piping material, in which the piping material and the cored bar are rotated, displacing at least one passively rotating roller in an axial direction while compressing the outer periphery of the piping material, and pressuring and retaining the piping material between the cored bar and the at least one passively rotating roller, wherein a middle section of the piping material is made thinner than end sections thereof by moving the roller into a position closer to the cored bar in the middle section than in the end sections, and the cored bar includes a large diameter land at a connecting section between the thinner middle section and the end sections, the land suppressing inward swelling of an inner face of the piping material at the connecting section.