U.S. patent number RE32,248 [Application Number 06/573,306] was granted by the patent office on 1986-09-16 for grate for drainage ducts.
This patent grant is currently assigned to TWB-Pressteile GmbH. Invention is credited to Peter Blecher.
United States Patent |
RE32,248 |
Blecher |
September 16, 1986 |
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.
Inventors: |
Blecher; Peter (Hagen,
DE) |
Assignee: |
TWB-Pressteile GmbH (Hagen,
DE)
|
Family
ID: |
26080852 |
Appl.
No.: |
06/573,306 |
Filed: |
January 23, 1984 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
360889 |
Mar 22, 1982 |
04367142 |
Jan 4, 1983 |
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Current U.S.
Class: |
210/163; 404/2;
52/180; 52/302.1 |
Current CPC
Class: |
E03F
5/06 (20130101); E01C 11/227 (20130101) |
Current International
Class: |
E01C
11/00 (20060101); E01C 11/22 (20060101); E03F
5/06 (20060101); E03F 005/14 () |
Field of
Search: |
;210/163-166 ;404/2
;52/303,180 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Adee; John
Attorney, Agent or Firm: Harness, Dickey & Pierce
Claims
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.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a ladder-type grate of sheet steel
for drainage ducts, which grate is of the type that is provided
with upright longitudinal edges which are angled with respect to
oppositely disposed longitudinal edges and supporting bars disposed
between the longitudinal edges, each supporting bar being separated
from an adjacent supporting bar by an intake slit having an edge
which is crimped in the upright direction of the longitudinal edges
and merges, parallel to each supporting bar, into an oblique intake
surface.
Drainage ducts are intended to drain traffic surfaces. They receive
the incoming precipitation water in lines and conduct it away.
Drainage ducts are formed by the lining up of duct elements, i.e.
elongate drainage structures having a trough-shaped cross section
and covered by grates or covers. Drainage ducts are classified
according to the location at which they are installed.
For testing purposes, forces are exerted on the duct elements and
on the grates and covers, such forces being of different magnitudes
depending on location and classification of the drainage ducts.
Grates for traffic surfaces traveled exclusively by pedestrians and
bicycles, whose classification in class A, are subjected to a test
force of 15 kN; grates for footpaths, pedestrian areas, automobile
parking lots and automobile parking decks, classified as class B,
to a test force of 125 kN; grates for curbstones in streets and
pedestrian paths, median and side strips, and parking lots, which
are classified as class C, are subjected to a test force of 250
kN.
Grates of the above-mentioned type easily withstand the low force
test; withstand the medium force tests only under certain
conditions; and they do not withstand the high force test at all.
The reason for this is that in the transition region from the
intake slit into the longitudinal edge only the sheet metal without
any reinforcement must support the bearing, or test, force.
For use under medium and heavy loads, grates made of cast iron are
therefore employed. However, compared to grates of the
above-mentioned type, cast iron grates are heavy and expensive.
Moreover, they are brittle so that there exists the danger of
breakage during handling, including transport, installation,
removal and disassembly for cleaning, as well as under asymmetrical
loads.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a
novel grate for drainage ducts which is made of sheet metal and is
constructed in such a manner that it is able to withstand even high
loads.
The above and other objects are achieved, according to the
invention, 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, and 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, by
constituting the grate of sheet steel inner and outer components
one of which is provided with the slits and each of which is
provided with the supporting bars, providing the inner component
with longitudinal bars extending along opposite sides thereof,
providing the outer component with angled longitudinal edge parts
extending along opposite sides thereof, and disposing the inner
component within the outer component with the longitudinal bars
held in the longitudinal edge parts, and the supporting bars of the
inner component resting against those of the outer component.
The objects according to the invention are further achieved by
producing the above-defined grate according to the following
sequence steps:
providing two sheet metal pieces to constitute respective ones of
the grate components;
pressing recesses and stop humps into the outer grate component
piece, and forming the lateral bars and supporting bars in the
inner grate component piece, in such a manner that the supporting
bars of the inner grate component have side walls extending
transversely to the main surface portion;
forming the inlet surfaces of the slits, partly forming the
longitudinal edge parts of the outer component so that the partly
formed parts extend transversely to the main surfce portion, and
forming the longitudinal bars of the inner component to extend
transversely to the main surface portion; and
inserting the inner component into the outer component; and
finally forming the longitudinal edge parts by bending the
extremity of each edge part toward the other edge part for engaging
the inner component longitudinal bars.
Among the advantages realized by the invention are that the grate
is able to withstand not only all loads but particularly those
corresponding to Classes B and C, and also remains light-weight and
unbreakable. The grate according to the invention is additionally
stabilized in the transverse direction by the supporting bars, and
in the longitudinal direction by the lateral bars, of the inner
grate.
The invention provides that an exterior grate of a certain sheet
metal thickness is associated with interior grates of a different
sheet metal thickness to thus adapt the load carrying capacity to
the prevailing stresses. The limit to possible variations lies only
in the width of the back of the supporting bar for the inner grate
which is placed into the supporting bar of the outer grate.
The lateral bars of the inner grate, on the one hand, which are
held between the angled longitudinal edges of the outer grate, and
the supporting bars of the inner grate held between the oblique
intake surfaces of the supporting bars of the outer grate, on the
other hand, form a stable connection which requires no additional
fastening means. Rather the inner grate is held immovably in the
outer grate.
The inner grate does not interfere with drainage since the inlet
slits of the outer grate remain completely exposed. Cleaning of
such a grate is also not impaired. The outer and inner grates may
be made, in a known manner, of Sendzimir zinc-galvanized steel
sheet, of steel sheet, hot galvanized after molding or of stainless
steel sheet. It is advantageous to press stop humps into the
surface of the outer grate as protection against sliding.
--Sendzimir zinc-galvanising denotes a hot dip zinc coating without
flux.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 shows, approximately to scale, a top plan view of a
preferred embodiment of a grate according to the invention, of
which only the part following one frontal face is shown.
FIG. 2 is a longitudinal cross-sectional view through part of the
grate along the section line II--II of FIG. 1.
FIG. 3 is an end elevational view of the grate shown in FIGS. 1 and
2.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The illustrated grate for drainage ducts includes an outer grate
component 1 and an inner grate component disposed within the outer
component 1. Each of the components 1 and 2 has the shape of a
ladder and is made of a respective steel sheet.
The outer grate component 1 has two longitudinal edges 11 each of
which consists of an upright edge portion 12 and a portion 13 which
is angled with respect to portion 12 and extends toward the
opposite longitudinal edge. Supporting bars 14 extend between the
longitudinal edges 11. Edges 11 and bars 14 constitute integral
parts of a one-piece member. An inlet slit 16 is disposed between
each adjacent pair of supporting bars 14. Each inlet slit 16 has an
edge 18 which is bent out of the plane of the major face of
component 1 to extend parallel to edge portions 12. Between the
major face of component 1, which corresponds to the major faces of
bars 14, and each edge 18, there is a transition portion presenting
an inlet face 17 which is oblique to the major face of component
1.
The inner grate component 2 is formed of two longitudinal bars 21
and shaped supporting bars 22 integral with, and extending between,
the bars 21. The inner grate component 2 is held via its
longitudinal bars 21 between the angled longitudinal edges 11 of
the outer grate component 1. The supporting bars 22 of the inner
grate component 2 rest against the supporting bars 14 of the outer
grate component.
Each bar 21 of the inner grate component 2 is formed of an upright
edge strip of the associated steel sheet. Each supporting bar 22 is
formed as an inverted trough whose cross-sectional profile has
essentially the form of an inverted U. The bases 23 of the
supporting bars 22 of the inner grate component 2 rest against the
lower, or inside, surfaces of the supporting bars 14 of the outer
grate component 1. The end faces 24 of the side walls 25 of the
supporting bars 22 abut against the bars 21. At each end face, the
base 23 of each supporting bar 22 merges into a longitudinal bar
21.
Since the supporting bars 22 of the inner grate component 2 are
made of the same sheet steel piece as the longitudinal bars 21, it
is possible, if the spacing of the inlet slits 16 of the outer
grate 1 is given, for the supporting bars 22 of the inner grate
component 2 to be spaced apart so that, as in the illustrated
embodiment, a bar 22 rests only against every other supporting bar
14 of the outer grate component 1. If the inlet slits 16 of the
outer grate component 1 are arranged at a greater distance from one
another or if the faces 12 are made shorter, it is possible, while
adhering to the principle that the outer grate component 1 and the
inner grate 2 are each to be made of a respective steel sheet, to
provide the component 2 with supporting bars 22 arranged so that
one bar 22 rests against each supporting bar 14 of the outer grate
component 1. The load carrying capability of the grate can also be
increased by using a stronger steel sheet for the inner grate
component to give the longitudinal bars 21 and the supporting bars
22 thicker side walls and thus an increase in stability.
The inner grate component 2 is held in the outer grate component 1,
on the one hand, by its longitudinal bars 21 between the angled
longitudinal edges 11 and, on the other hand, by its supporting
bars 22 in contact with the supporting bars 14 located between
angled inlet faces 17. The inner grate component 2 is thus held
immovably in the outer grate component 1 and no additional
fastening means are required.
The grate is manufactured most easily in the following manner:
In a first process step, indentations to form faces 17 and edges 18
and the stop humps 15 are pressed into a steel sheet intended for
the outer grate component 1. Simultaneously, but separately
therefrom, the contours of the longitudinal bars 21 and of the
supporting bars 22 are cut in a steel sheet intended for the inner
grate component 2.
In the second process step, the indentations in the steel sheet
intended for the outer grate component 1 are cut open and the end
sections are cut off. Separately therefrom, the side walls 25 of
the supporting bars 22 of the inner grate component 2 are
simultaneously bent upright.
In the third process step, the inlet faces 17 at the supporting
bars 14 and the longitudinal edges 11 of the outer grate 1 are bent
upright. Separately therefrom the longitudinal bars 21 of the inner
grate component 2 are bent upright. Then the inner grate component
2 is inserted into the outer grate 1 so that the supporting bars 22
are nested in the supporting bars 14.
Then the extremities of the longitudinal edges 11 of the outer
grate component 1 are bent to form portions 13 which are pressed
around the bars 21 of the inner grate component 2. The
above-mentioned process steps can be performed on the same press in
a machine that operates in steps.
As can be seen in FIGS. 2 and 3, each end of the grate is provided
with a tab extending at right angles to the major surface of the
grate and the edges 11. Each tab is provided with bores for
fastening adjacent grates together.
It will be understood that the above description of the present
invention is susceptible to various modifications, changes and
adaptations, and the same are intended to be comprehended within
the meaning and range of equivalents of the appended claims.
* * * * *