| 摘要 |
Metal door frame and the like made of channel iron open from outside without any need of welding or other kind of connections of jambs and upper part, and method of their manufacture. The jambs and header of the frame are made of a single part of a rolled channel iron having a complicated, asymmetrical shape generally in the form of a letter "U". In the area of a corner, the channel iron is provided, on walls which are perpendicular to the inner side of the door frame, with suitable cut-outs shaped as a triangle and a trapezoid for making it possible to bend the channel iron into a right angle corner. The superfluous material in the plane of the channel iron, forming the inner sides of the door frame and in other planes parallel to it, forms, after having bent the channel iron into corner, tongues, which may protrude from the frame for a better fixing of the door frame in the brickwork. Some of the tongues, or all of them, may be bent, respectively, toward the jambs and toward the header of the door frame for a better tightening of the bent corners between successive parts of the frame. |
