Bolts, nuts, washers, and bolt-nut tightening structures

摘要

PROBLEM TO BE SOLVED: To make possible (combined use) a bolt (10) and a washer (20) for tightening bolt nuts of a convex portion (P portion) and a concave portion (Q portion) in an overlapping portion of a corrugated material (50). .. A bolt (10) has a seat surface (12) having a concave curved surface portion (12a) (P portion) forming a concave curved surface when viewed from the X direction on an orthogonal plane orthogonal to the bolt center axis, and in the X direction. It has a convex curved surface portion 12b (Q portion) which forms a convex curved surface when viewed in the Y direction which is orthogonal to it. The washer 20 has a seat surface 22 having a convex curved surface portion 22b (P portion) that forms a convex curved surface when viewed from the X direction on an orthogonal plane orthogonal to the washer central axis, and has a concave curvature when viewed from the Y direction. It has a concave curved surface portion 22b (Q portion) forming a surface. The bolt 10 and the washer 20 can be used for both the convex portion (P portion) and the concave portion (Q portion) of the corrugated material by changing the direction around the central axis of the bolt by 90°. The curved plate washer 30 need only be turned upside down. [Selection diagram] Figure 1