| 摘要 |
PURPOSE:To decrease the number of processes, to generate no return burr, and to make a shape of a chamfered part constant by forming a stepped part having a projecting curved surface on the inner surface part of a cylindrical body by a stepped part of a punch, when forming the cylindrical body, and thereafter, cutting the outside position of the stepped part and forming an aperture end. CONSTITUTION:A metallic material which can be brought easily to a plastic deformation is formed to a cylindrical body 2 by a press work by using a punch 1 having a stepped part 1a whose corner part is a recessed curved surface, on the outside peripheral surface of a necessary position. When forming the cylindrical body 2, simultaneously, a stepped part 2a whose corner part is a projecting curved surface is formed on the inner surface part by the stepped part 1a of the punch 1, and thereafter, the corner part of the cylindrical body 2 is cut vertically in the axial direction, in the stepped part 2a of the projecting curved surface or the outside position of the stepped part, and a cap 3 is completed. In this way, chamfering becomes unnecessary, no return burr is generated, and a shape of the chambered part becomes constant. |
