| 摘要 |
PROBLEM TO BE SOLVED: To provide a pipe bending method for improving versatility of a design of a control by obtaining a large bending angle of a pipe, and improving the bending accuracy without causing wrinkles, dents or twists in the pipe, and to provide a mandrel used for the method. SOLUTION: Curved surfaces 91 and 92 and a shape regulating surface 93 are provided on a tip part of a mandrel 9 to be used for bending a side frame upper 2. The curved surfaces 91 and 92 are formed as surfaces retracting from an inner surface of the side frame upper 2 while the mandrel 9 is inserted inside the side frame upper 2. The shape regulating surface 93 is formed as a surface to be in contact with the inner surface of the side frame upper 2 without any space while the mandrel 9 is inserted inside the side frame upper 2. Bending is performed so that a side with the curved surfaces 91 and 92 formed thereon forms an outer circumferential side in the direction of the radius of curvature of the bending. COPYRIGHT: (C)2004,JPO
|
