Method and apparatus for manufacturing box-shaped structure from metal sheet

Abstract

A safe box-like structure of good appearance is formed in a simplified manner from a flat metal sheet by folding at right angles the opposite side portions of a flat rectangular metal sheet, for instance, of a steel sheet to provide a channel-shaped metal sheet, forming in each end portion of the upright side sections of the channel-shaped metal sheet a diagonal crease extending from an inner end of a prescribed vertical fold line disposed substantially perpendicular to the bottom section of the bottom section of the channel-shaped metal sheet to the outer corner point of the end portion of the side section, pressing a triangular intermediate section between the prescribed vertical fold line and the diagonal crease inwardly of the channel-shaped metal sheet, folding the triangular intermediate section and an outer triangular section toward each other along the afore-mentioned prescribed vertical fold line and diagonal crease, and upbending opposite end portions of the channel-shaped metal sheet at right angles, putting inside the wedge-shaped portions consisting of overlapped triangular sections which are formed at the joints of the adjacent side and end sections of the box-like structure, thereby precluding the dangers which would be otherwise invited by exposed wedge-shaped portions.

Dependencies are inferred from the claim text.