Procedure for Manufacturing a Roof Element

The present invention concerns a procedure for manufacturing a roof element, wherein between two metal sheets is foamed, or between them is fixed by glueing, a thermal lagging such as polyurethane.

Manufacturing procedures like this known in the art present the drawback that shearing the pre-profiled top metal sheet by the so-called guillotine principle is difficult. The shearing has to be accomplished in two steps. When a lagging processed by foaming such as polyurethane is used, points of escape difficult to control are formed on the long sides of the element. The lagging material flows into the crevices of the folds for joining by machine and is difficult to remove. The folds to be joined by machine add about 30 mm to the thickness of the element, thus wasting effective pressing space in the mould at different manufacturing steps. When the roof element is manufactured on a so-called continuous moulding line, the top and bottom sheet have to be inserted in the machine formed to present their final profiled shape. The consequence is greater space required for the apparatus longitudinally, and it implies difficult technical solutions.

The object of the present invention is to eliminate the drawbacks presented above. The procedure of the invention is characterized in that subsequent to fixing the lagging, the folds required for joining by machine are profiled on the edges of the top sheet by a roller forming technique. The invention enables the top sheet to be cut with conventional sheet metal cutters while it is smooth. It becomes possible to place the smooth top sheet in the mould with the best conceivable sealing, thereby avoiding detrimental flowout. The space occupied by the machine-joining folds is now efficiently usable. Five instead of four elements can be manufactured in the same press interval. In the case of a continuous moulding line, the top sheet is introduced from a reel into the moulding line, whereby the manufacturing no longer differs essentially from the manufacturing of a simple thermal lagging element.

The invention is describerd in the following by the aid of an example, referring to the drawing attached, wherein

FIGS. 1 to 4 present the profiling of the margins of the top sheet of a roof element, in its different steps, when manufacturing a roof element provided with polyurethane lagging.

In the roof element manufacturung procedure, polyurethane 1 is introduced and foamed in the space between the top and bottom sheets 2,3. It is not until after the foaming of the polyurethane 1 that joining folds 4,5 required for joining by machine are profiled by a roller moulding technique on the margins of the top sheet 2. The element of FIG. 1 is placed on a roller track, fitted on opposite sides with profiling stations. FIGS. 2 and 3 illustrate the progress of the margin profiling, that is, the generation of the folds for machine joining. The completed product is presented in FIG. 4.