| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a cylindrical shaft 20 having a high uniform roundness over a whole length by bending a metal sheet. SOLUTION: Dies 52, 62 are provided with a working surface 61 of a semi-circular shape, each of whose cross sections orthogonal to a longitudinal direction has the same inner diameter as the outer diameter of the cylindrical shaft 20, and are provided with a straight groove having a linear inner surface shape at each of whose cross sections parallel to the longitudinal direction of the cylindrical shaft 20. Punches 54, 64 are provided with working surfaces 53, 63 of a semi-circular shape, each of whose cross sections orthogonal to the longitudinal direction has the same inner diameter as the outer diameter of the cylindrical shaft 20, and are provided with a curved groove having the working surfaces 53, 63 of a convex curved shape, each of whose cross sections parallel to the longitudinal direction of the cylindrical shaft 20 has gradually a higher draft rate to the cylindrical shaft 20 toward the center in the longitudinal direction. Using these dies and punches, the cylindrical shaft 20 is shaped while clamping the cylindrical shaft 20 between the straight groove and the curved groove in such a way that the deepest part of the groove of the curved die comes into contact with the joint part of the metal sheet 10 for the cylindrical shaft 20. COPYRIGHT: (C)2009,JPO&INPIT
|
