| 摘要 |
PURPOSE:To prepare simply and correctly a belt-like groove on the outer peripheral plane and a protrusion on the inner peripheral plane by forming an indentation on the outer peripheral plane of a cylindrical conductive material and pressing a roller on the indentation. CONSTITUTION:A cylindrical conductive material is prepared and forms the indentation 14 on its outer peripheral plane by cutting. The conductive cylinder 12 formed with the indentation 14 is rotated around its axis and a roller 16 is pressed on the indentation 14. The conductive material is plastically deformed by the roller 16 to form the belt-like groove 17 around the outer peripheral plane and the belt-like protrusion 18 is formed on the inner peripheral plane.
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