Process of manufacture and steel sheet manhole cover of steel sheet manhole cover for gutter cover

摘要

PURPOSE: A manhole cover unit and a method of manufacturing a manhole cover unit for a drain cover are provided to reduce contamination and weight by manufacturing the manhole cover unit using a steel sheet. CONSTITUTION: A method of manufacturing a manhole cover unit(A) is as follows. A disc steel-sheet becomes a flat steel-sheet by punching press. A cylindrical body is formed by the drawing of the disc steel-sheet by drawing press. Protrusions(211) and grooves(211') are formed by forming press. A plurality of reinforcing pieces are coupled to the inside of the cylindrical body. A method of manufacturing a manhole cover frame(10) is as follows. A guide frame(630) is formed on the top of the floor frame(520). Reinforcing ribs(720) are welded between the outer circumferential surfaces of a welded floor frame and the guide frame.