| 摘要 |
There is provided a bending portion including a bending piece set in which a plurality of bending pieces are pivotably continuously provided, the bending pieces being formed by cutting a rigid pipe while a convex portion is formed on a bending piece one side and a concave portion is formed on a bending piece other side, the convex portion and the concave portion forming an engagement portion that pivotably couples the bending pieces to each other. The engagement portion includes: a first engagement portion including a first convex portion formed on the bending piece one side and a first concave portion on which the first convex portion slides formed on the bending piece other side, the first convex portion and the first concave portion being formed simultaneously by cutting; and a second engagement portion including a pair of second convex portions formed on the bending piece other side to sandwich the first concave portion and a pair of second concave portions on which the pair of second convex portions respectively slide formed on the bending piece one side, the pair of second convex portions and the pair of second concave portions being formed simultaneously by cutting. The bending pieces are each provided with any one of: a first reinforcing portion for making a width of a bending piece end on one end side larger by cutting out part of a bottom portion of the first concave portion; and a second reinforcing portion for making a width between bottom surfaces of the pair of second concave portions and a bending piece end on the other end side larger. |
