Grate for drainage ducts

Abstract

A ladder-like grate for use in drainage ducts, which grate includes a main surface portion and opposed, upright longitudinal edges extending along respective longitudinal sides of the main surface portion, is produced from two sheet metal components at least one of which is provided with slits and each of which is provided with supporting bars. One component is an inner component which includes longitudinal bars extending along opposite sides thereof. The other component is an outer component which includes angled longitudinal edge parts extending along opposite sides thereof. The components are assembled together with the inner component within the outer component, the longitudinal bars held in the longitudinal edge parts, and the supporting bars of the inner component resting against those of the outer component.

What is claimed is: 
     
       1. In a ladder-like grate made of sheet steel for use in drainage ducts, which grate includes a main surface portion and opposed, upright longitudinal edges extending along respective longitudinal sides of the main surface portion, each edge including a part which is angled toward the other longitudinal edge, the grate further including supporting bars extending between the longitudinal edges and formed to define inlet slits each extending between the longitudinal edges and each located between two adjacent supporting bars, the grate further being formed to present, around each slit, a folded-down edge establishing an inlet surface oriented obliquely to the main surface portion, the improvement wherein said grate comprises sheet steel inner and outer components one of which is provided with said slits and each of which is provided with said supporting bars, and wherein said inner component includes longitudinal bars extending along opposite sides thereof, said outer component includes angled longitudinal edge parts extending along opposite sides thereof, and said components are assembled together with said inner component within said outer component, said longitudinal bars held in said longitudinal edge parts, and said supporting bars of said inner component resting against those of said outer component. 
     
     
       2. Grate as defined in claim 1 wherein said longitudinal bars of said inner grate component are formed of sheet metal portions extending transversely to said main surface portion. 
     
     
       3. Grate as defined in claim 2 wherein said supporting bars of said inner grate component have the form of inverted troughs having bases which bear against respective supporting bars of said outer grate component and having side walls presenting axial end faces which abut against said longitudinal bars of said inner component. 
     
     
       4. Grate as defined in claim 1, 2 or 3 wherein said outer grate component is of a defined sheet metal thickness, and said inner grate component has a sheet metal thickness selected from a plurality of thickness values. 
     
     
       5. A method of producing the grate defined in claim 1, 2 or 3 comprising: providing two sheet metal pieces to constitute respective ones of said grate components;   pressing recesses and stop humps into said outer grate component piece, and forming said lateral bars and supporting bars in said inner grate component piece, in such a manner that said supporting bars of said inner grate component have side walls extending transversely to said main surface portion;   forming the inlet surfaces of said slits, partly forming said longitudinal edge parts of said outer component so that the partly formed parts extend transversely to said main surface portion, and forming said longitudinal bars of said inner component to extend transversely to said main surface portion;   inserting said inner component into said outer component; and finally forming said longitudinal edge parts by bending the extremity of each said edge part toward the other said edge part for engaging said inner component longitudinal bars. .Iadd.   
     
     
       6.  In a ladder-like grate for use in drainage ducts comprising an outer component formed from thin sheet like material comprising a main surface portion and opposed, upright longitudinal edges extending along respective longitudinal sides of the main surface portion, each edge including a part which is angled toward the other longitudinal edge, said main surface being formed to define a plurality of spaced inlet slits each extending between said longitudinal edges and defined by folded-down edges and a plurality of transversely extending supporting bars extending between said longitudinal edges in the area between said inlet slits, said supporting bars being in engagement with at least a portion of the main surface extending between said inlet slits and supported by said outer components. .Iaddend. .Iadd.7. In a ladder-like grate as set forth in claim 6 wherein the supporting bars are engaged by the folded-down edges. .Iaddend. .Iadd.8. In a ladder-like grate as set forth in claim 6 wherein the supporting bars are formed from sheet metal and the outer component is formed from sheet metal. .Iaddend. .Iadd.9. In a ladder-like grate as set forth in claim 8 wherein the supporting bars are engaged by the folded-down edges. .Iaddend. .Iadd.10. In a ladder-like grate as set forth in claim 9 wherein the supporting bars have a U-shaped cross-section. .Iaddend. .Iadd.11. In a ladder-like grate as set forth in claim 6 wherein there are a lesser number of supporting bars than inlet slits.